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Moss, Rachel Ann. "Intra-individual reaction time variability in sustained attention." Thesis, University of Newcastle upon Tyne, 2018. http://hdl.handle.net/10443/4083.
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BACKGROUND: Sustained attention, assessed using the Continuous Performance Test (CPT), is impaired in 'normal' ageing and, to a greater degree, in a number of clinical disorders. There are many variants of the CPT, each with different task parameters (e.g., target frequency), and theoretical cognitive demands (e.g., executive functioning). It is unclear how the associated cognitive load of CPTs contributes to measures of attentional impairment, such as intra-individual variability (IIV) in reaction time (RT). There is potential clinical utility in measures of IIV, due to its relationship with increasing age, and brain white matter. Variability can be modelled using the ex-Gaussian distribution, and consists of three parameters: mu (mean RT), and IIV, decomposed into variability across the entire RT distribution (sigma), and characterised by infrequent and long RTs (tau). This thesis aims to examine how the multiple cognitive demands of CPTs contributes to attentional RT/IIV, and how this relationship interacts with age, as well as pathology. The thesis aims are explored in healthy and clinical populations characterised by sustained attention impairment associated with increasing age ('normal' ageing and Parkinson's disease (PD)), or in theoretical 'accelerated ageing' (Bipolar disorder (BD) while depressed and in remission). METHODS: Sustained attention was assessed in five cross-sectional studies, using variants of the CPT. Secondary neuropsychological measures of executive functioning, processing speed, and verbal memory were administered. Ex-Gaussian distributional parameters (mu, sigma, and tau) obtained from CPT RTs were analysed. A series of hierarchical regression analyses were examined. RESULTS: (1) In 'normal' ageing, better performance on the secondary neuropsychological measures was associated with faster RT (mu) and more consistent responding (sigma, tau), but this varied across CPT. Similar results were obtained for the effect of age on RT and IIV. (2) In PD, better executive functioning was associated with consistent responding (tau), whilst age was associated with slower (mu) and inconsistent (tau) responding. (3) In BD (while depressed), better executive functioning was associated with slower responding (mu), and better processing speed with consistent responding (tau), whilst age did not explain variance in RT or IIV. (4) In BD (in remission), the secondary neuropsychological measures examined did not explain variance in RT or IIV, nor did age. vi CONCLUSIONS: Attentional RT and IIV in 'normal' ageing and in clinical populations such as PD and BD, may be supported by secondary neuropsychological processes theorised to be involved in CPT variants. The neuropsychological profile underpinning attentional RT and IIV may reflect secondary cognitive scaffolding mechanisms, engaged depending on the age of participants, rather than the cognitive load of the task per se. The results have implications for our understanding of attentional RT and IIV in 'normal' ageing and pathology. Future research would further our understanding on the use of cognitive scaffolding in relation to the CPT, as well as the stability, reliability, and neurobiological origins of RT and IIV.
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Jouvet, Lionel. "Mytilus edulis haemocytes variability : technique, individual and environment." Thesis, Heriot-Watt University, 2010. http://hdl.handle.net/10399/2367.
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The widely distributed marine bivalve Mytilus edulis is used as a sentinel organism for ecological and toxicological assessments. As a filter feeder, it has the potential to bio-accumulate pollutants. It has been assumed that the cell concentration and cell type ratio of its circulating immune cells, haemocytes, could become complementary sub-lethal indicators of toxicology. These two parameters are respectively referred to as total haemocyte count (THC) and differential cell count (DCC). This study examines these commonly used methods, quantifies their limitations, and develops alternative techniques. The circulating immune cells are investigated to assess their fluctuations. Finally, impacts of environmental challenges on the circulating haemocytes are examined. Despite its importance in the field of Mytilus edulis immunology, THC evaluation is present in only 20% of publications in this field, and DCC in 10%. Ultimately, only 9% of papers consider both THC and DCC before further analyses. The remaining studies disregard THC and DDC, or regard these parameters as being constant and homogenous in M. edulis populations. This study initially quantifies the systematic error induced by sampling, and suggests improvements. For example, a systematic error of 26% is attributed to the use of low precision syringes, and can be reduced with use of higher precision sampling equipment. While the systematic errors in visual count and image analysis of THC and DCC evaluations are equivalent, the computerised methods allow the throughput of larger data sets, reduce workload, and avoid tedious eye counts. Flow cytometry was found to be the most accurate method in THC and DCC evaluation. Furthermore, repeated bleedings influence DCC, triggering the decrease of circulating eosinophils (up to 20%) and the increase of hyaline cells (up to 30%). To mitigate this reaction to sampling, a maximum volume of 50μl using a permanent cannulation is recommended. However, even with improved methods reducing systematic error by half, this study still reports variations as high as 20-fold in the haemocyte concentration in populations of healthy individuals. In addition, over a 2-hour period in a single cannulated individual, fluctuation of the DDC is observed to be as high as 30% for eosinophils, 10% for hyaline cells, and 20% for basophils. These measured variations are explained by haemocyte reservoirs in the tissues. Eosinophils are found in large numbers in epithelial association in the gills, guts and in the mantle, where their numbers have been evaluated at 3x10 7 As a case study, Mytilus edulis challenged with barium sulphate smothering, used by the oil industry in drilling muds, shows gill damage and their subsequent infiltration by eosinophils. In bacterial outbreak, basophilic cells are observed to infiltrate the tissue surrounding the stomach and eosinophils are depleted from the epithelium of the digestive tissues. THC is 10-fold lower than in healthy organisms and eosinophils are depleted from the haemolymph. cells. In conclusion, the THC and DDC methods are shown to be unreliable despite the use of more accurate methods. In addition, Mytilus edulis circulating haemocytes present large variations and the assumption of their homogeneity in terms of time, individuals or methods used cannot be made. These results challenge the conclusions of many past publications regarding causalities established between potential stresses and measured effects. Further research is necessary to understand the mechanisms regulating the circulating haemocytes, the inter-individual variability and to improve investigation methods.
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Alkhaldy, Areej. "Inter-individual variability of polyphenol metabolism and colonic health." Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/5763/.
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It has been proposed that polyphenol-rich foods have a role in disease prevention and are associated with health benefits due to their antioxidant, anti-inflammatory, prebiotic, and antibacterial properties. However, associated health benefits depend on their intake, metabolism, and bioavailability. The metabolism and the bioavailability of polyphenols have been studied in young adults and show substantial variability. As the majority of polyphenols are metabolised in the colon, this may result in different bioactive microbial metabolites in the large intestine where they may have an impact on the risk of colorectal cancer (CRC). This variability could be due to: 1) dietary habits including intake polyphenol-rich foods; 2) ethnic-specific colonic microbiota; and 3) ageing and its effect on colonic physiology. Little is known about the impact of ethnicity, ageing, and the risk of CRC on polyphenol metabolism. Therefore, this thesis aimed to investigate the effect of the factors that could have an impact on the colonic metabolism of dietary polyphenols in a human feeding study measuring the biomarkers of polyphenol metabolism, colonic fermentation, and gut health; and an in-vitro faecal fermentation study measuring the colonic metabolites of quercetin-3-O-rutinoside (rutin). The first aim of this thesis (Chapter 3) was to examine the effect of ethnicity (Europeans versus Indians) on polyphenol metabolism. The findings of this study suggest that ethnicity could have a role on the colonic metabolism of polyphenols which could be due to the differences in disease incidence between countries such as the lowest risk of CRC in India among the world. The Indian group excreted less urinary phenolic acid after the high-polyphenol diet compared to the Europeans; however, Indians were more capable and faster in metabolizing rutin in the in-vitro model. This could be due to the differences in: 1. Genetics and its effect on gastrointestinal tract absorption. 2. Gut microbiota, as Indians have a significantly higher level of Bifidobacterium. 3. Gut environment, in particular the colonic pH and SCFA could have an influence as the colonic pH was lower in the Indian group. 4. Cultural daily diet between groups, as Indians significantly consumed a high amount of onions, tomatoes, chillies, spices, curry-based products, and yoghurt. These food types are high in polyphenols, fibre, and probiotics. The second study of this thesis aimed to investigate the effect of ageing on polyphenol metabolism. The results suggest another factor, ageing, which could influence the colonic metabolism of polyphenols. The older group excreted less urinary phenolic acid and some of the acid was not detected in certain of the participants’ urine compared to the younger group. However, the sum of the phenolic acid that formed after the faecal fermentation of rutin was not significantly different between the groups. This could suggest different reasons behind these variations. First, the lack of absorption of some phenolic acids by the older group as ageing was shown to decrease the colonic absorption. Secondly, the effect of ageing on gut microbiota composition and function. Thirdly, changes in dietary habits and physical activity may be influenced by ageing. Thus, this may suggest that older people can have fewer benefits of polyphenol metabolites which could be associated with an increase in risk for age-related diseases including CRC. As the risk of CRC is different between countries and increases with age, the supportive findings of the first and second study suggest that ethnicity and ageing could have a role on the metabolism of polyphenols so this raises the questions whether a low intake of polyphenols can be one of the factors that may lead to CRC, or whether polyphenols can reduce the risk of CRC due to their colonic health benefits. Therefore, the last study examined the metabolism of polyphenols on patients who are at risk of CRC (history of polyps). No significant differences were observed between the healthy control and polypectomy groups in terms of the sum urinary phenolic acid excretion and phenolic acid formation in the faecal fluids. However, some phenolic acids were not detected in all of the urine samples of the polypectomy group as well as one acid in the faecal fermentation fluids, while some of the acids were not detected in few participants in the healthy group. No hard conclusion can be made from this study due to the small sample size. However, this study gives us an idea that there could be differences if a larger sample size were used. Therefore, more studies are needed to determine the effect of CRC risk as being one of the factors that can influence the metabolism of polyphenols. In conclusion, the work of this thesis showed that ethnicity, ageing, and gut health are likely some of the key factors that could contribute to the variations in polyphenol metabolism which were observed previously by many in-vivo and in-vitro studies. These variations could result in bioavailability variation and consequential differences in the biological activity of polyphenol metabolites leading to differences in health and optimal health among individuals.
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Brothers, Michael Dunton. "Acclimatization to moderate altitude: Physiological implications and individual variability." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3256402.
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Klein, Simon. "Causes and consequences of individual forager variability in social bees." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30099/document.
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Chez les pollinisateurs sociaux, comme l'abeille domestique (Apis mellifera L.) et le bourdon terrestre (Bombus terrestris L.), mes deux modèles d'étude, différents individus sont spécialisés dans différentes tâches. Il est admis que différents types de comportement de butinage contribuent à une optimisation des performances de la colonie. Actuellement, les populations de pollinisateurs sont exposées à des stress environnementaux, qui sont connus pour perturber le comportement des individus en visant directement leur cognition. Il est ainsi crucial de mieux comprendre comment les colonies d'abeilles et de bourdons maintiennent une activité de butinage efficace, et quels sont les effets de stress environnementaux sur les butineuses. Dans cette thèse, j'ai donc examiné les différentes stratégies de butinage pour différentes sources de nourriture, pollen et nectar, et les variabilités interindividuelles dans le comportement de butinage. Je me suis aussi intéressé à l'impact de stress tels que les pesticides sur l'efficacité de butinage. J'ai utilisé la technologie RFID pour suivre le comportement des abeilles tout au long de leur vie. J'ai trouvé que les colonies d'abeilles et de bourdons reposent sur un petit groupe d'individus très actifs qui fournissent la majorité de la nourriture pour la colonie. Chez les abeilles, ces individus très actifs sont aussi plus efficaces pour collecter nectar et pollen. J'ai aussi identifié l'existence de différentes stratégies pour la collecte de pollen ou de nectar. Ensuite, j'ai pu montrer que les bourdons ont des différences interindividuelles très marquées dans un test de navigation, une tâche cruciale dans le comportement de butinage. Finalement, j'ai testé l'effet néfaste de pesticides sur l'apprentissage visuel chez l'abeille. Cette thèse a pour but de mieux comprendre les causes de vulnérabilité des pollinisateurs aux stress environnementaux. Mes résultats soulignent le besoin de considérer la diversité comportementale comme une adaptation des espèces de pollinisateurs sociaux, mais aussi comme une potentielle cause de vulnérabilité de la colonie vis-à-vis des stressIn social insects, such as bees, different individuals specialise in the collection of different resources, and it is assumed that natural behavioural variability among foragers contributes to a self-organised optimisation of colony performance. Currently, bee populations are facing an increasing number of environmental stressors, known to disturb the behaviour of individuals, presumably upon their impact on cognitive capacities. Hence it is important to learn more about how stressors impact on individual foraging behaviour to understand how a colony maintains effective nutrition and development. In this thesis in cognitive ecology, I examined the different foraging strategies for the different macronutrient sources, pollen and nectar, and the inter-individual variation in bee foraging performance. I also looked at how stressors, such as pesticides, can impact on bee foraging efficiency. I compared two social Hymenoptera that vary in their level of social complexity: the European honey bee (Apis mellifera L.) and the buffed-tailed bumblebee (Bombus terrestris L.). I used Radio Frequency Identification (RFID) to automatically track the foraging behaviour of bees throughout their life. I found that honey bee and bumblebee colonies rely on a subset of very active bees to supply the whole colony needs. In honey bees, these foragers are more efficient and collect more pollen. I also identified different strategies for pollen or nectar collection in both species. Using manipulative experiments, I then showed that bees exhibit consistent inter-individual different behaviours in a spatial learning task and that pesticides impair visual learning. My thesis aims at better explaining the causes of vulnerability of pollinators to sublethal pesticides and other environmental stressors. The results highlight the need for considering behavioural diversity as an adaptation for social insects, as well as a potential dimension of colony-level vulnerability to environmental stressors that can impair the whole colony nutritional balance
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Chaikan, Ammara. "Uniderstanding inter-individual variability in the pharmacokinetics of protease inhibitors." Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548778.
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Dykiert, Dominika. "Determinants and correlates of intra-individual variability in reaction time." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5919.
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Traditionally, reaction time (RT) was conceived of as an average speed of a number of responses made by an individual, or mean RT. Increasingly, however, intraindividual variability in reaction time (RT IIV) – the consistency of responses by a single person across trials – is used as an additional or even alternative measure. RT IIV is often found to be elevated in a number of conditions that affect the central nervous system functioning, such as traumatic brain injury or neurodegenerative diseases. It can predict change in cognitive performance in ageing, progression from normal ageing to mild cognitive impairment, and even death. Therefore, RT IIV may be of great practical importance. However, RT IIV and mean RT are correlated; therefore it is often problematic to draw conclusions about unique associations between these and other variables. One objective of the work presented in this thesis was to investigate determinants and correlates of simple and choice RT IIV and to test which associations may be accounted for by the individual differences in mean RT. The first investigation was concerned with age differences in RT IIV. Following a systematic review of literature, a series of meta-analyses demonstrated that older individuals (aged 60 years and above) have greater RT IIV than young or middle-aged adults in simple and choice RT tasks. The effects were reduced but still significant when RT IIV was adjusted for mean RT. The next study was a cross-sectional investigation of the associations between age and RT IIV, as well as of sex differences in RT IIV, across the lifespan in participants ranging in age from 4 to 75. Non-linear effects of age were found for RT IIV measures, such that variability decreased with age in children and increased with age in older adults. A novel finding from this study was that sex differences in RT IIV were present among adults but not children, suggesting that there might be an age threshold at which sexes diverge in their RT IIV trajectories. The results also indicated that findings regarding RT IIV may differ depending on the variability measure used (that is, whether and how mean RT is controlled). The second study on the same sample investigated variability on a trial-by-trial basis. Specifically, it tested the hypothesis that sex differences in variability are due to females being disproportionately slower at the first trial which inflates their overall RT IIV. This hypothesis was not supported. Another investigation used longitudinal data from the West of Scotland Twenty-07 study. Three cohorts of individuals aged approximately 15, 35 and 55, were followed up for 20 years and had RT data collected at four occasions. Analyses confirmed non-linear effects of age on RT IIV found in the earlier cross-sectional investigation. The final study investigated the effect of high altitude on RT IIV. It found that altitude-related increase in RT IIV is fully accounted for by general slowing of RT at high altitude. The overall pattern of results obtained from the investigations suggests that RT IIV increases with age in adults and that not all of the increase is due to general slowing. Moreover, the results show that sex differences in RT IIV are not uniform across the lifespan. Finally, whereas associations of RT IIV with some variables, for example age, are relatively robust to controlling for mean RT, others are fully attenuated by such practice.
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Ulman, Sophia Marie. "Gait Variability for Predicting Individual Performance in Military-Relevant Tasks." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/94346.
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Human movement is inherently complex, requiring the control and coordination of many neurophysiological and biomechanical degrees-of-freedom, and the extent to which individuals exhibit variation in their movement patterns is captured by the construct of motor variability (MV). MV is being used increasingly to describe movement quality and function among clinical populations and elderly individuals. However, current evidence presents conflicting views on whether increased MV offers benefits or is a hindrance to performance. To better understand the utility of MV for performance prediction, we focused on current research needs in the military domain. Dismounted soldiers, in particular, are expected to perform at a high level in complex environments and under demanding physical conditions. Hence, it is critical to understand what strategies allow soldiers to better adapt to fatigue and diverse environmental factors, and to develop predictive tools for estimating changes in soldier performance. Different aspects of performance such as motor learning, experience, and adaptability to fatigue were investigated when soldiers performed various gait tasks, and gait variability (GV) was quantified using four different types of measures (spatiotemporal, joint kinematics, detrended fluctuation analysis, and Lyapunov exponents).
During a novel obstacle course task, we found that frontal plane coordination variability of the hip-knee and knee-ankle joint couples exhibited strong association with rate of learning the novel task, explaining 62% of the variance, and higher joint kinematic variability during the swing phase of baseline gait was associated with faster learning rate. In a load carriage task, GV measures were more sensitive than average gait measures in discriminating between experience and load condition: experienced cadets exhibited reduced GV (in spatiotemporal measures and joint kinematics) and lower long-term local dynamic stability at the ankle, compared to the novice group. In the final study investigating multiple measures of obstacle performance, and variables predictive of changes in performance following intense whole-body fatigue, joint kinematic variability of baseline gait explained 28-59% of the variance in individual performances changes.
In summary, these results support the feasibility of anticipating and augmenting task performance based on individual motor variability. This work also provides guidelines for future research and the development of training programs specifically for improving military training, performance prediction, and performance enhancement.Doctor of Philosophy
All people move with some level of inherent variability, even when doing the same activity, and the extent to which individuals exhibit variation in their movement patterns is captured by the construct of motor variability (MV). MV is being increasingly used to describe movement quality and function among clinical populations and elderly individuals. However, it is still unclear whether increased MV offers benefits or is a hindrance to performance. To better understand the utility of MV for performance prediction, we focused on current research needs in the military domain. Dismounted soldiers, in particular, are expected to perform at a high level in complex environments and under demanding physical conditions. Hence, it is critical to understand what strategies allow soldiers to better adapt to fatigue and diverse environmental factors, and to develop tools that might predict changes in soldier performance. Different aspects of performance were investigated, including learning a new activity, experience, and adaptability to fatigue, and gait variability was quantified through different approaches. When examining how individual learn a novel obstacle course task, we found that certain aspects of gait variability had strong associations with learning rate. In a load carriage task, variability measures were determined to be more sensitive to difference in experience level and load condition compared to typical average measures of gait. Specifically, variability increased with load, and the experienced group was less variable overall and more stable in the long term. Lastly, a subset of gait variability measures were associated with individual differences in fatigue-related changes in performance during an obstacle course. In summary, the results presented here support that it may be possible to both anticipate and enhance task performance based on individual variability. This work also provides guidelines for future research and the development of training programs specifically for improving military training, performance prediction, and performance enhancement.
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Lord-Maes, Janiece Marie. "Short latency evoked potentials and intra-individual variability in children." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184623.
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Individual differences in learning with a focus on neuropsychologic anomalies underlying learning strategies has been receiving attention in recent years. As a result, interest has increased in quantifying and analyzing cognitive behavior more directly. One of the tools that measures brain activity directly is the evoked potential (EP). This study investigated the EP recorded from the brainstem region, often referred to as brainstem auditory evoked response (BAER). The importance of BAERs in detecting pathology in the brainstem has been well documented. BAERs have also been advocated as an important tool in the electrophysiological assessment of children's brainstem function relative to learning disorders. BAER latencies were recorded, therefore, from a small group of average children and studied in relation to the BAER stability overtime. Intra-individual differences were compared to between-subject differences. So little BAER research has been performed with children that more studies are needed just to clarify normal variability of BAER parameters. The present investigation studied intra-individual differences in the stability of BAER latencies over time in young subjects with normal hearing, for comparing with and contrasting to previous results from a study using an adult sample. BAER latencies were recorded for left, right, and binaural ear presentations. A coefficient of stability (CS) was calculated for each peak, for each ear over time. ANOVA results showed significance for peak and peak by ear interaction. Several BAER parameters were examined within-subjects that may not be revealed in studies between-subjects. Profiles for intra-aural differences over time showed individual differences in the stability of the BAER. Although there appeared to be a trend toward inter-ear differences the differences did not reach significance. The profiles indicated considerable intra-aural pattern replicability, and a trend toward increase in stability over time. The results supported a need for future research on laterality studies, more age specific normative data and correlational studies in relation to individual cognitive differences.
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Aglieri, Virginia. "Behavioural and neural inter-individual variability in voice perception processes." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0176/document.
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Chez l'homme, la voix facilite les interactions sociales par la transmission d’informations sur l'identité de la personne, ses émotions ou sa personnalité. En particulier, l'identité du locuteur peut être automatiquement extraite même lorsque le message et l'état émotionnel varient, ce qui suggère des mécanismes cognitifs et cérébraux partiellement dissociables pour ces processus. Cependant, la reconnaissance d'une voix familière ou la discrimination entre deux locuteurs sont, pour certains sujets, non seulement non-automatiques, mais même impossibles. Ce déficit, lorsqu'il se manifeste dès la naissance, est appelé phonagnosie du développement et constitue la contrepartie auditive de la prosopagnosie (déficit de reconnaissance des visages). Dans le domaine visuel, il a été proposé que les sujets affectés par la prosopagnosie du développement représentent des cas extrêmes dans la distribution des capacités de reconnaissance de visages. A l’inverse, des "super-reconnaisseurs" des visages se situaient à l’opposé de cette distribution.Comme la distribution des capacités de reconnaissance de la voix dans la population générale était encore inconnue, le premier objectif de cette thèse a été d'en étudier les différences individuelles au moyen d'un court test - le Glasgow Voice Memory Test (GVMT). Les résultats obtenus ont reflété une large variabilité interindividuelle dans les capacités de reconnaissance des voix: parmi une cohorte de 1120 sujets, il y avait à la fois des sujets avec des performances significativement en dessous de la moyenne (potentiels phonagnosiques) et des "super-reconnaisseurs" des voix. Cette variabilité individuelle comportementale semblerait se refléter au niveau cérébral, comme révélés par l'imagerie par résonance magnétique fonctionnelle (IRMf) : en fait, il a été montré précédemment qu'il existait une variabilité interindividuelle considérable dans le signal BOLD (blood-oxygen level dependent) lié à la voix dans les zones temporales de la voix (TVAs). Ces régions sont situées sur le bord supérieur des sulcus/gyrus temporal supérieur (STS/STG) et montrent une activation préférentielle pour les sons vocaux plutôt que non vocaux. Le deuxième objectif de ce travail fut de mieux caractériser le lien entre les mécanismes comportementaux et neuronaux sous-tendant la variabilité interindividuelle dans les processus de reconnaissance des voix. Pour cela, nous avons examiné comment la perception de la voix modulait la connectivité fonctionnelle entre les TVAs, constituant le "noyau" du réseau de perception de la voix, et les régions frontales également sensibles aux voix, constituant une extension de ce réseau. Les résultats ont montré qu'il y avait une connectivité fonctionnelle positive dans l'ensemble du réseau et que la connectivité fonctionnelle fronto-temporelle et fronto-frontale droite augmentait avec les scores obtenus lors du GVMT.Pour compléter ce travail, nous avons réalisé une autre étude IRMf en utilisant des analyses multivariées, afin de clarifier les corrélats neuronaux de la reconnaissance du locuteur mais aussi le lien entre sensibilité cérébrale à la voix et capacités de reconnaissance du locuteur. Pour cela, des sujets ayant des capacités de reconnaissance vocale hétérogènes ont été soumis à la fois à une tâche d'identification du locuteur et à une tâche d'écoute passive de sons vocaux et non vocaux. Les résultats ont confirmé que l’identification du locuteur s’effectuait via un réseau étendu de régions, incluant les TVAs mais aussi des régions frontales. De plus, nous avons observé que le score de classification voix/non-voix dans le STS droit permettait de prédire les capacités d'identification des locuteurs.Dans l'ensemble, ces résultats suggèrent que les capacités de reconnaissance vocale varient considérablement d'un individu à l'autre et que cette variabilité pourrait être le reflet de profils d’activité cérébrale différents au sein du réseau de la perception de la voixIn humans, voice conveys heterogeneous information such as speaker’s identity, which can be automatically extracted even when language content and emotional state vary. We hypothesized that the ability to recognize a speaker considerably varied across the population, as previously observed for face recognition. To test this hypothesis, a short voice recognition test was delivered to 1120 subjects in order to observe how voice recognition abilities were distributed in the general population. Since it has been previously observed that there exists a considerable inter-individual variability in voice-elicited activity in temporal voice areas (TVAs), regions along the superior temporal sulcus/gyrus (STS/STG) that show preferentially activation for voices than other sounds, the second aim of this work was then to better characterize the link between the behavioral and neural mechanisms underlying inter-individual variability in voice recognition processes through functional magnetic resonance imaging (fMRI). The results of a first fMRI study showed that functional connectivity between frontal and temporal voice sensitive regions increased with voice recognition scores obtained at a voice recognition test. Another fMRI study showed that speaker’s identity was treated in an extended network of regions, including TVAs but also frontal regions and that voice/non-voice classification accuracy in right STS increased with speaker identification abilities. Altogether, these results suggest that voice recognition abilities considerably vary across subjects and that this variability can be mirrored by different neural profiles within the voice perception network
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Jay, Tim. "Explaining individual differences in strategy variability amongst secondary school mathematics students." Thesis, University of Nottingham, 2007. http://eprints.nottingham.ac.uk/10424/.
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This thesis reports an investigation of individual differences in children's learning of a concept in mathematics, involving rates of change on linear graphs. Evidence in the literature suggests both that high levels of strategy variability are associated with conceptual change in mathematics and that there are individual differences in strategy variability. Therefore it is argued that differences in strategy variability can offer useful insight into children's learning of mathematics. A series of experiments are reported that each aimed to explore individual and group differences in strategy variability amongst secondary school mathematics students. Methods used for data collection progressed from whole-class testing of students, to individual testing, to individual interviews employing think-aloud protocols, as the need grew for increasingly detailed data on children's strategies for solving problems. Early studies showed a gender difference in strategy variability, so later studies were designed to elaborate on and clarify this relationship. In combination, the results of the studies reported here suggest that there are robust differences in strategy variability between boys and girls and that this effect interacts with the context in which the problems are solved. The use of think-aloud protocols produced a complete reversal of the gender effect on strategy variability. The implications of these findings are discussed, both in terms of learning theory and in terms of their potential impact on the mathematics classroom. The main contribution of this investigation to the literature is in helping to establish strategy variability as a key to understanding cognitive development and as an indicator of children's specific needs for intervention and support in the classroom.
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Nowparast, Rostami Hadiseh. "Biological mechanisms underlying inter- and intra- individual variability of face cognition." HKBU Institutional Repository, 2016. https://repository.hkbu.edu.hk/etd_oa/444.
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Given the importance of correctly perceiving and remembering faces for successful social interaction, face processing is one of the most widely studied cognitive domain in behavioral, neurophysiological and neuroimaging research, particularly, based on a group-mean approach. However, above mean differences, inter- and intra-individual variability in face processing provide valuable information for investigating the underlying mechanisms and binding the behavioral and neural substrates for better understanding of face processing.. In my dissertation I investigated the biological mechanisms underlying face cognition from an inter- and intra-individual variability perspective at the genetic, neural, and behavioral levels. The neural activities related to face processing are measured by event-related potentials (ERPs) and their trial-by-trial latency variability are estimated using a novel and well-established method, Residue Iteration Decomposition (RIDE).. Study 1 demonstrates the reliability of RIDE in extracting single-trial parameters of the P3b component, which is used in the investigation of the neural basis of intra-subject variability (ISV) in face processing speed in Study 2. In the Study 2, individual differences in ISV of face processing speed, measured at both behavioral and neural levels during a face processing task, are studied in their genetic variation. The results suggest that individual differences in ISV are related not only to the COMT Val158Met polymorphism, but also to the type of cognitive processing (e.g., memory domain). Moreover, we showed that ISV in reaction time can be partially explained by ISV in the speed of central cognitive processes.. Furthermore, the individual differences approach in Study 3, provided valuable and novel information beyond the common group-mean approach applied in the N1/N170-related research. Based on this approach, not only we could replicate previous findings that the N170 predicts individual differences in face cognition abilities, but also we could decompose individual differences in the N170 into a domain-general and a face-specific part with different predictive powers. Moreover, we showed that top-down modulations on the N170 have separable and qualitatively different relationships to face cognition abilities.. In summary, the integrated results from different studies in my dissertation demonstrate the psychological importance of the information provided by inter- and intra-individual variability in face processing in the investigation of its underlying biological mechanisms.
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Nowparast, Rostami Hadiseh. "Biological Mechanisms underlying Inter- and Intra-Individual Variability of Face Cognition." Doctoral thesis, Humboldt-Universität zu Berlin, 2017. http://dx.doi.org/10.18452/18077.
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In dieser Arbeit untersuche ich der Gesichterkognition zugrundeliegende biologischen Mechanismen auf der genetischen, neuronalen und verhaltensbasierten Ebene. Die neuronale Aktivität wurde mittels ereigniskorrelierter Potenziale (EKPs) untersucht und ihre Latzenzvariabilität innerhalb der Person wurde durch eine innovative Methode, Residue Iteration Decomposition (RIDE), gemessen.
Die erste Studie demonstriert die Reliabilität von RIDE für die Extraktion von Einzeltrialparametern der P3b Komponente, welche in der zweiten Studie die Basis für die Untersuchung der Innen-Subjekt-Variabilität (ISV) bei der Geschwindigkeit der Gesichterkognition bildet. Die zweite Studie untersucht individuelle Unterschiede in ISV in ihrer genetischen Variation, gemessen an der Verhaltens- und neuronalen Ebene während einer Gesichterkognitionsaufgabe. Die Ergebnisse zeigen, dass ISV nicht nur mit dem COMT Val158Met Polymorphismus zusammenhängt, sondern auch von der geforderten kognitiven Verarbeitung abhängt. Zudem ist die ISV in der Reaktionszeit teilweise durch die ISV in der Geschwindigkeit zentralkognitiver Prozesse erklärbar.
Studie 3 liefert neuartige Informationen für die N1/N170 Forschung. Mit einem differentialpsychologischen Ansatz konnten wir nicht nur vorangegangene Ergebnisse zur Vorhersagekraft der N170 für individuelle Unterschiede in der Gesichterkognition replizieren, sondern auch die individuellen Unterschiede in der N170 in einen allgemeinen und einen gesichtsspezifischen Teil mit unterschiedlicher Vorhersagekraft zerlegen. Darüber hinaus konnten wir zeigen, dass top-down Modulationen der N170 unterscheidbare und qualitativ unterschiedliche Beziehungen zu Fähigkeiten der Gesichterkognition aufweisen.
Insgesamt zeigen die integrierten Ergebnisse der Studien meiner Dissertation die psychologische Bedeutsamkeit der intra- und interindividuellen Variabilität in der Gesichterkognition für die Erforschung der ihr zugrundeliegenden biologischen Mechanismen.The biological mechanisms underlying face cognition from an inter- and intra-individual variability perspective at the genetic, neural, and behavioral levels are investigated. The neural activities related to face processing are measured by event-related potentials (ERPs) and their trial-by-trial latency variability are estimated using a novel and well-established method, Residue Iteration Decomposition (RIDE). Study 1 demonstrates the reliability of RIDE in extracting single-trial parameters of the P3b component. In the Study 2, individual differences in ISV of face processing speed, measured at both behavioral and neural levels during a face processing task, are studied in their genetic variation. The results suggest that individual differences in ISV are related not only to the COMT Val158Met polymorphism, but also to the type of cognitive processing (e.g., memory domain). Moreover, we showed that ISV in reaction time can be partially explained by ISV in the speed of central cognitive processes. Furthermore, the individual differences approach in Study 3, provided valuable and novel information beyond the common group-mean approach applied in the N1/N170-related research. Based on this approach, not only we could replicate previous findings that the N170 predicts individual differences in face cognition abilities, but also we could decompose individual differences in the N170 into a domain-general and a face-specific part with different predictive powers. Moreover, we showed that top-down modulations on the N170 have separable and qualitatively different relationships to face cognition abilities. In summary, the integrated results from different studies in my dissertation demonstrate the psychological importance of the information provided by inter- and intra-individual variability in face processing in the investigation of its underlying biological mechanisms.
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Hardy, Jaime. "DISTINGUISHING AMONG WITHIN-PERSON VARIABILITY: AFFECTIVE INTRA-INDIVIDUAL VARIABILITY, AFFECTIVE PSYCHOLOGICAL FLEXIBILITY, AND HEALTH IN A NATIONAL US SAMPLE." UKnowledge, 2015. http://uknowledge.uky.edu/psychology_etds/64.
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Affective intra-individual variability (IIV) and affective psychological flexibility (PF) are both types of within-person variability. Affective IIV is defined as the range of emotions experienced by an individual assessed at multiple time points. PF is defined as the ability to vary one’s responses in a contextually dependent manner in order to appropriately meet situational demands. Currently, there are no comparisons between affective IIV and PF demonstrating how these constructs might be uniquely different from each other. The current study proposed to examine affective IIV and PF in order to establish discriminant and convergent validity, and stability data for each construct. The National Study of Daily Experiences (NSDE) waves 1 and 2, an 8-day daily diary portion of the Midlife Development in the United States (MIDUS I) and MIDUS II surveys was used for this study (n =793 adults completed both waves of the NSDE). Affective IIV was related to higher mean NA and neuroticism, and lower perceived control. Affective PF was related to lower mean NA, neuroticism, and higher mean PA and perceived control. Higher affective IIV was associated with more psychological distress when assessed concurrently at both waves and predicted more psychological distress and physical ill-health 10 years later. Higher affective PF was related to less psychological distress and physical ill-health when assessed concurrently at wave 1 and less psychological distress and physical ill-health 10 years later. When situational context is included in the calculation of emotional variability, changes in emotional response may represent emotional complexity and increased control rather than emotional lability and are related to better psychological and physical outcomes.
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McPhee, Jamie Stewart. "Endurance training : central and peripheral adaptations in relation to inter-individual variability." Thesis, Manchester Metropolitan University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496616.
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Considerable variability exists between people in their health- and performance-related adaptations to training. The variability is usually ascribed 1 to genetic diversity, but there are also mechanistic explanations that are often overlooked. The work described in this thesis examined factors (non-genetic and genetic) that contribute to inter-individual variability in endurance-phenotypes and responses to endurance training.
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Saville, Christopher W. N. "Individual differences in reaction time variability : A combined psychometric and electroencephalographic approach." Thesis, Bangor University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.529751.
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Wakeling, Luisa Anne. "Genetic influences on inter-individual variability in soyabean isoflavone absorption and metabolism." Thesis, University of Newcastle Upon Tyne, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443018.
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Kassab, Somar. "Variabilité du virus de l'hépatite B." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0056/document.
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Le polymorphisme génétique du virus de l’hépatite B (VHB) a déjà été étudié pourtenter de comprendre les facteurs viraux influençant l'évolution de la maladie, mais les étudessont discordantes. Ceci peut être lié au fait que les précédents travaux n’ont été menés quedans des populations avec une faible variété de génotypes et présentant des charges viralesplasmatiques (CVP) élevées.Nous avons donc étudié la variabilité du génome complet du VHB chez 422 individusinfectés chroniquement, naïfs de traitements anti-viraux et dont 38% présentaient une CVPinférieure à 103 UI/mL. L’optimisation de l’amplification par PCR du génome complet duVHB nous a permis de séquencer en technique Sanger plus de 90% du génome pour 320échantillons. Le séquençage direct a mis en évidence des co-infections. Ceci a été confirmé enséquençage clonal par pyroséquençage de 27 échantillons qui a montré des proportions departicules défectives variables mais toujours en co-infections avec des sous-populationssauvages. Le génotypage des séquences obtenues par technique Sanger a montré une grandereprésentativité des génotypes les plus fréquents (A à E) ainsi que 60 potentiels recombinantsinter-génotypiques. Cependant le séquençage clonal par pyroséquençage et clonage vectorielclassique de ces derniers montre la présence de co-infections de plusieurs génotypes ou laprésence de génotypes intermédiaires entre génotypes proches. Ceci est en défaveur derecombinaison par échange de matériel génétique comme ce qui a été suggéré dans lalittérature.Cette étude sera complétée par l’analyse de corrélation entre les polymorphismes et lesmarqueurs de mauvaise évolution de la pathologieThe genetic polymorphism of hepatitis B virus (HBV) has been investigated tounderstand its impact on disease evolution, with discordant results. This could be due to thenarrow range of genotype and plasmatic viral load in these studies.We analysed complete genome variability of circulating HBV, in 422 chronicallyinfected patients. All were naive of anti-viral treatement and 38% had a plasmatic viral loadbelow 103 UI/mL. After optimisation of full length genome PCR amplification, we obtainedSanger sequences for more than 90% of HBV genome in 320 samples. We detected by directsequencing multiples co-infections that were confirmed by clonal pyrosequencing in 27samples. Defective viruses were always observed in co-infection with wild type virus. Directsequences showed a large representation of the most frequent genotypes (A to E), but also 60potential inter-genotypic recombinants. Clonal pyrosequencing and vectorial sequencingshowed that these potential recombinants were co-infections with different genotypes orintermediate genotypes located between close genotypes. These observations are incontradiction with the hypothesis described in the literature on recombination by geneticmaterial exchange.This study will be completed by a correlation analysis between the polymorphisms andmarkers of bad prognosis during HBV-induced disease
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Dickinson, Laura. "Factors influencing inter-individual variability in pharmacokinetics of antiretrovirals in HIV-infected patients." Thesis, University of Liverpool, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431721.
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Forbes, Heather. "Individual variability in the behaviour and morphology of larval Atlantic cod (Gadus morhua, L.)." Thesis, Connect to e-thesis. Move to record for print version, 2007. http://theses.gla.ac.uk/48/.
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Thesis (Ph.D.) - University of Glasgow, 2007.Ph.D. thesis submitted to the Division of Environmental and Evolutionary Biology, Institute of Biomedical and Life Sciences, University of Glasgow, 2007. Includes bibliographical references. Print version also available.
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Caudwell, Phillipa. "Individual variability in the impact of physical activity on appetite behaviour and body weight." Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505086.
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Hilborn, Anne Winona. "The effect of individual variability and larger carnivores on the functional response of cheetahs." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/82040.
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Functional response is the framework thorough which we can quantify how predator hunting behaviors such as rate of successful attack and time spent handling prey interact with prey density to determine the rate at which prey are killed. Cheetahs are mesopredators and their behavior can be shaped by the need to avoid larger predators while hunting relatively large bodied and mobile prey. I used data from 34 years of observed cheetah hunts in Serengeti National Park in Tanzania to investigate how reproductive condition, prey density, seasonality, and the proximity of larger predators affect cheetah kill rates, probability of successful attack, and time spent handling prey. Mothers with cubs had an asymptotic Type II functional response where kill rate increased but eventually leveled-off at high prey densities, while cheetahs without cubs had a dome shaped Type IV functional response where kill rates actually declined at high prey density. Probability of successful attack on prey was higher for mothers with cubs, and increased slightly with prey density. Mothers with cubs had different prey handling behavior than other cheetahs. Cheetah mothers spend longer at kills then other cheetahs despite the risk that the carcass can attract lions and hyenas that could steal the carcass and potentially kill her cubs. Mothers must make sure their cubs have sufficient time at the carcass to eat their fill, thus they minimize risk from larger predators by being vigilant. In contrast, cheetahs without cubs are unconcerned with cub predation and can eat quickly to minimize the risk of kleptoparasitism. My results show how the pressures of cub rearing and coexisting with larger carnivores differentially shape the hunting behavior of cheetahs, and suggest that intensity of mesopredator suppression may depend on individual variability. This is the first time the functional response for a large mesopredator, has been quantified and the first time a dome shaped response has been recorded in a mammal. My work shows the value in accounting for individual variability in functional response and how linking of carnivore hunting behavior to multiple species interactions advances our understanding of how classical ecological theory applies to wild ecosystems.Ph. D.
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Smith, Michael Edward. "Causes and consequences of individual growth rate variability in red drum (Sciaenops ocellatus) larvae /." Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3055247.
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Cubitt, Kathleen Fiona. "Individual growth variability in farmed Atlantic salmon (Salmo salar L.) : the role of social interactions." Thesis, University of Glasgow, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394832.
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Erskine, Robert MacDonald. "The inter-individual variability in human muscle strength and in the response to resistance training." Thesis, Manchester Metropolitan University, 2010. http://e-space.mmu.ac.uk/188890/.
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Inter-individual differences in strength are not fully explained by muscle size, suggesting that muscle specific tension [force per unit physiological cross-sectional area (PCSA)] varies between untrained individuals. Furthermore, many reports demonstrate greater gains in muscle strength than size following resistance training, thus indicating an increase in specific tension. Moreover, there is considerable variation in the response to training that may have a genetic origin. The aims of the work described in this thesis were i) to examine the degree of variability in muscle specific tension; ii) to investigate whether specific tension changed following resistance training; iii) to quantify the variability in the response of human muscle to resistance training; iv) to identify gene variants that may be associated with the variable training responses. In a group of untrained young men and before and after 9 weeks of resistance training, the quadriceps femoris (QF) muscle specific tension was calculated from the maximum isometric voluntary contraction (MVC) torque, taking into account the contribution of voluntary activation, antagonist muscle co-activation, moment arm length, QF volume, muscle fascicle length and pennation angle. Correcting for these factors made little difference to the between subjects variance of MVC torque, thus demonstrating that muscle specific tension varies considerably between individuals. Resistance training increased QF muscle force much more than PCSA, indicating that most of the increase in force was a result of increased specific tension. This increase was not associated with a change in myosin heavy chain expression and was not accompanied by an increase in single fibre specific tension, or an increase in power per unit muscle volume measured during isokinetic cycling. The results are consistent with an increase in lateral force transmission in the muscle. Substantial variation in the training responses was observed and the final part of this thesis is concerned with linking this variation with specific gene variants.
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Susilo, Yusak Octavius. "The Short-term Variability and the Long-term Changes of Individual Spatial Behavior in Urban Areas." 京都大学 (Kyoto University), 2005. http://hdl.handle.net/2433/123476.
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Mead, Michael Phillip. "The Theory of Planned Behavior and Sleep Opportunity: An Ecological Momentary Assessment of Intra-Individual Variability." Diss., North Dakota State University, 2020. https://hdl.handle.net/10365/31927.
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Insufficient sleep duration is associated with poor physical and mental health outcomes, and many Americans report that they are not meeting sleep duration recommendations. Many individuals choose to restrict their own sleep, yet little is known about the source of this sleep deficit. Recent research efforts have used the Theory of Planned Behavior (TPB) to predict sleep health behavior. However, this research is limited in that it fails to measure volitional sleep behavior and focuses exclusively on between-person differences. This study addressed these limitations by using an intensive longitudinal design to test how constructs of the TPB relate to nightly sleep opportunity. Healthy college students (N=79) completed a week long study in which they completed 4 ecological momentary assessment signals per day that measured their attitudes, perceived norms, perceived behavioral control (PBC), and intentions relating to their nocturnal sleep opportunity. Participants wore an actiwatch each night of the study to measure their sleep opportunity. Analyses revealed between- and within-day variability of attitudes, perceived norms, PBC, and intentions. Further, there were significant between- and within-day trajectories of these constructs. Mixed linear models demonstrated that both intentions and PBC were significant predictors of subsequent sleep opportunity, and that PBC was the strongest predictor of future intentions. The between-and within-day patterns of these constructs highlight important considerations for their measurement, and provide insight into the potential refinement of sleep promotion efforts. Results also demonstrate that within-person changes in PBC and intentions predict subsequent sleep opportunity, demonstrating the need for a daily framework when using the TPB to predict sleep health behavior.
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Dickmann, Leslie J. "Characterization of CYP2C9 residues important for conferring substrate specificity and inter-individual variability in drug metabolism /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/8184.
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Bedarida, Sandra. "Histoire naturelle et diversité génétique des virus de la famille anelloviridae : étude de prélèvements biologiques contemporains et anciens." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM5033.
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Les Anelloviridae sont de petits virus à ADN simple brin de découverte récente, très largement répandus chez les vertébrés. Chez l'homme, 3 genres distincts ont été caractérisés : Alphatorquevirus (TTV), Betatorquevirus (TTMV), Gammatorquevirus (TTMDV), engendrant une infection chronique mais dont le pouvoir pathogène potentiel demeure encore méconnu. Leur épidémiologie est en constante réévaluation du fait de leur extrême variabilité et diversité génétique. Au cours de cette recherche à l'interface entre virologie et paléomicrobiologie, nous avons exploré l'histoire naturelle de ces virus via 2 axes interconnectés. D'une part la diversité génétique a été analysée lors d'une étude transversale au sein de populations contemporaines (française et afghane) et de populations anciennes datant du néolithique à l'époque moderne. D'autre part, leur évolution a été étudiée à l'échelle individuelle par une étude longitudinale au sein de 2 corpus (suivis de patient transplanté et de patient hémodialysé). Dans le but de compléter les données concernant cette famille virale unique, un travail méthodologique a été mis en oeuvre afin d'apporter des améliorations et de standardiser les protocoles d'analyse existants. La comparaison de distribution des Anelloviridae parmi plusieurs populations contemporaines, nous a permis d'observer des différences significatives de profils, notamment dans la population afghane. Notre méthodologie d'analyse d'échantillons anciens a mis en évidence la présence de souches Anelloviridae, attestant ainsi leur ancestralité et révélant également l'existence de variabilités inter- et intra-individuelles, similaires à l'infection des populations modernesAnelloviridae are small single-stranded DNA viruses, recently discovered, and widely spread among vertebrates. In humans, three distinct genera were characterised: Alphatorquevirus (TTV), Betatorquevirus (TTMV), Gammatorquevirus (TTMDV), leading to a chronic infection whose pathogenicity remains unknown. Their epidemiology is constantly evolving due to their extreme variability and genetic diversity. In this multidisciplinary research, combining virology, bioanthropology and palaeomicrobiology, we have used genetic analysis to explore the natural history of those viruses via two linked issues. On the one hand, the genetic diversity was analysed by way of a cross-sectional study within contemporary populations (French and Afghan) and ancient populations from the Neolithic period to Modern times. On the other hand, their evolution was studied at the individual level through a longitudinal study in two corpora (follow-ups of a transplanted patient and haemodialysis patients). In order to complement data regarding this unique viral family, a methodological process was established to improve and standardize existing analysis protocols. Comparison of Anelloviridae's distributions among several healthy contemporary populations allowed us to notice significant differences of partitions, especially an almost complete absence of TTMDV in the Afghan sample. Our methodology dedicated to ancient remains displayed the presence of Anelloviridae strains, testifying their ancestral origin and highlighting inter- and intra-individual variations, similar to infections in modern populations
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Santucci, Aimee Kristin. "Individual Differences in Adults' Self-Report of Negative Affect and Effortful Control: Consequences for Physiology, Emotion, and Behavior During Regulatory Tasks." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/27569.
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Emotion regulation is processes by which individuals influence which emotions they have, when they have them, and how they experience and express those emotions. In the field of developmental psychology, there is a large literature on affect regulation focused almost exclusively on infants and young children with a focus on temperamental differences in reactivity, both affective and physiological, and accompanying regulatory strategies. The purpose of the current study was to examine the role of two dimensions of temperament, negative affect (NA) and effortful control (EC), and how these dimensions relate to physiology, self-report of emotion, and behavior during resting and stressor tasks (Stroop, video game, hand cold pressor, and delayed gratification), the latter in which emotion suppression instructions were given. Using the Adult Temperament Questionnaire (ATQ) to screen 656 subjects, 24 males and 53 females were recruited to take part in the second phase of the study, creating four groups with their screening ATQ scores: high NA/high EC, low NA/low EC, high NA/low EC, low NA/high EC. Physiological measures derived from electrocardiogram (ECG) and impedance cardiography were recorded during each task and behaviors were coded using the Emotion Expressive Behavior Coding System. EC Group and NA Group were not significant for the majority of the physiological, self-report, and behavioral variables. However, the EC subscale inhibitory control was predictive of lower resting HRV for females only, and the Extraversion/Surgency subscale Sociability was a significant predictor of cardiac sympathetic activity during the tasks, with low sociability subjects showing a stronger sympathetic response. Neither self-report of emotion nor behavioral variables show a clear group difference in response to the tasks. Future studies will examine the use of other types of regulatory tasks, such as social interactions, as well as the need for a balance between emotion expressivity and emotion regulation.Ph. D.
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Speller, Lassiter F. "The Effects of Training and Individual Differences in Heart Rate Variability on the Golf Swing’s Coordination Structure." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1345224279.
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Durand, Maëva. "Alimentation sur mesure et estimation du bien-être des truies gestantes à partir de données hétérogènes." Electronic Thesis or Diss., Rennes, Agrocampus Ouest, 2023. http://www.theses.fr/2023NSARC169.
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Les nouvelles technologies se développent en élevage porcin, afin d’aider le travail des agriculteurs. Elles permettent la distribution d’une alimentation sur mesure pour des truies gestantes et une meilleure surveillance du comportement des animaux. La problématique de cette thèse est d’améliorer l’estimation des besoins nutritionnels journaliers et d’identifier l’état de bien-être individuel des truies gestantes, à l’aide de données comportementales et environnementales. Le premier objectif s’est intéressé à l’évaluation des effets des perturbations environnementales sur le comportement et les besoins nutritionnels. Pour cela, deux bandes de truies ont été suivies lors de deux gestations consécutives durant lesquelles différents évènements ont étéprovoqués. Les résultats ont permis de mettre en évidence l’influence des conditions environnementales sur le comportement et les besoins nutritionnels des truies au cours de leur gestation, et ont permis d’identifier une forte variabilité individuelle. Dans une deuxième partie, il s’agissait d’estimer individuellement les besoins journaliers et le bien-être, à partir des données comportementales et environnementales enregistrées par des capteurs. Les résultats ont montré que cette estimation peut être réalisée de façon précise grâce à différents algorithmes de machine learning sur des données produites par l’automate d’alimentation. Cette thèse propose donc des méthodes innovantes pour la conception d’un outil d’aide à la décision visant à améliorer l’alimentation sur mesure et le bien-être des truies gestantesNew technologies are developing increasingly in pig farming, to help farmers in their labour tasks. They allow the distribution of tailored diets for gestating sows and better animal behaviour monitoring. The issue of this thesis is to improve the estimation of daily nutritional requirements and estimate the individual welfare status of gestating sows using behavioural and environmental data collected automatically. The first aim was to evaluate experimentally the effects of environmental disturbances on behaviour and nutritional requirements. To achieve this, two groups of sows were followed during two consecutive gestations during which several events were induced. A database containing a variety ofsows’ behavioural data was built from these experiments. The results of the thesis highlighted the influence of environmental conditions on the behaviour and nutritional requirements of sows during gestation, as well as an important individual variability. The second part involved estimating individual daily requirements and welfare based on behavioural and environmental data recorded by sensors. The individual estimation of nutritional requirements and state of welfare can be carried out accurately using machine learning algorithms and data produced by the automatic feeder. Using these innovative methods, this thesis opens potential for the design of a decision-support tool aiming at adjusting feeding and improving the welfare of gestating sows
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Cui, J., Y. T. Cao, P. P. Lavvas, and and T. T. Koskinen. "THE VARIABILITY OF HCN IN TITAN’S UPPER ATMOSPHERE AS IMPLIED BY THE CASSINI ION-NEUTRAL MASS SPECTROMETER MEASUREMENTS." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621401.
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HCN is an important constituent in Titan's upper atmosphere, serving as the main coolant in the local energy budget. In this study, we derive the HCN abundance at the altitude range of 960-1400 km, combining the Ion-Neutral Mass Spectrometer data acquired during a large number of Cassini flybys with Titan. Typically, the HCN abundance declines modestly with increasing altitude and flattens to a near constant level above 1200 km. The data reveal a tendency for dayside depletion of HCN, which is clearly visible below 1000 km but weakens with increasing altitude. Despite the absence of convincing anti-correlation between HCN volume mixing ratio and neutral temperature, we argue that the variability in HCN abundance makes an important contribution to the large temperature variability observed in Titan's upper atmosphere.
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Sommer, Werner [Gutachter], Changsong [Gutachter] Zhou, and Jan [Gutachter] Wacker. "Biological Mechanisms underlying Inter- and Intra-Individual Variability of Face Cognition / Gutachter: Werner Sommer, Changsong Zhou, Jan Wacker." Berlin : Humboldt-Universität zu Berlin, 2017. http://d-nb.info/1189326914/34.
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Koay, J. Y., M. Vestergaard, H. E. Bignall, C. Reynolds, and B. M. Peterson. "Parsec-scale radio morphology and variability of a changing-look AGN: the case of Mrk 590." OXFORD UNIV PRESS, 2016. http://hdl.handle.net/10150/621462.
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We investigate the origin of the parsec-scale radio emission from the changing-look active galactic nucleus (AGN) of Mrk 590, and examine whether the radio power has faded concurrently with the dramatic decrease in accretion rates observed between the 1990s and the present. We detect a compact core at 1.6 and 8.4 GHz using new Very Long Baseline Array observations, finding no significant extended, jet-like features down to similar to 1 pc scales. The flat spectral index (alpha(8.4)(1.6) = 0.03) and high brightness temperature (T-b similar to 10(8) K) indicate self-absorbed synchrotron emission from the AGN. The radio to X-ray luminosity ratio of log(L-R/L-X) similar to -5, similar to that in coronally active stars, suggests emission from magnetized coronal winds, although unresolved radio jets are also consistent with the data. Comparing new Karl G. Jansky Very Large Array measurements with archival and published radio flux densities, we find 46 per cent, 34 per cent, and (insignificantly) 13 per cent flux density decreases between the 1990s and the year 2015 at 1.4 GHz, 5 GHz and 8.4 GHz, respectively. This trend, possibly due to the expansion and fading of internal shocks within the radio-emitting outflow after a recent outburst, is consistent with the decline of the optical-UV and X-ray luminosities over the same period. Such correlated variability demonstrates the AGN accretion-outflow connection, confirming that the changing-look behaviour in Mrk 590 originates from variable accretion rates rather than dust obscuration. The present radio and X-ray luminosity correlation, consistent with low/hard state accretion, suggests that the black hole may now be accreting in a radiatively inefficient mode.
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Yerkes, Tina J. "The influence of age, body mass, and environmental variability on individual variation in reproductive behaviors of female redhead ducks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ32039.pdf.
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Kraus, Ute [Verfasser], and Annette [Akademischer Betreuer] Peters. "Individual exposure to noise and ultrafine particles and its association with heart rate variability / Ute Kraus. Betreuer: Annette Peters." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2016. http://d-nb.info/110289706X/34.
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Fonseca, Filipa Alexandra Ponte. "Farmacogenómica." Master's thesis, [s.n.], 2014. http://hdl.handle.net/10284/4510.
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Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências FarmacêuticasDiferenças inter-individuais na eficácia e toxicidade da medicação são comuns entre os pacientes. Estima-se que a genética possa explicar entre 20 a 95 por cento da variabilidade na resposta aos fármacos. Porém associados à genética, existem fatores tais como, a idade, sexo, doenças secundárias e outros fatores ambientais que afetam a absorção, distribuição, metabolização e excreção dos fármacos podendo levar, habitualmente, à ocorrência de reações adversas. Estas reações são responsáveis por milhões de hospitalizações e milhares de mortes por ano apenas nos Estados Unidos. Identificação e caracterização de um grande número de polimorfismos genéticos (biomarcadores) nas enzimas metabolizadoras e transportadoras dos fármacos pode fornecer um conhecimento aprofundado sobre os mecanismos de diferenças inter- individuais na resposta à droga. O uso de novas tecnologias moleculares, nomeadamente de sequenciação do genoma, e de diagnóstico para avaliar o perfil genético e os biomarcadores das doenças abrem novos caminhos para permitir a cada doente o esquema de tratamento que lhe pode trazer os melhores resultados. Este esquema de tratamento, além de diminuir o número de reações adversas evita a exposição do paciente a um longo período de terapia baseado na tentativa e erro. Para os doentes, a medicina personalizada detém a promessa de terapêuticas mais eficazes e com menos efeitos secundários, podendo assim, ser poupados à perspetiva de um tratamento com efeitos adversos significativos e pouco ou nenhum efeito terapêutico Farmacogenética e farmacogenómica são duas áreas que emergiram para investigar a variabilidade individual na resposta aos fármacos. A indústria farmacêutica utiliza, cada vez mais, técnicas relacionadas com a farmacogenómica e com a farmacogenética e a informação que delas resulta para o processo de desenvolvimento de novos fármacos, promovendo a prescrição de um medicamento apropriado na dose certa para cada paciente. Inter-individual differences in the efficacy and toxicity of medication are common among patients. It is estimated that genetic factors can account for 20 to 95 percent of variability in drug responses. However associated with genetic, there are factors such as age, sex, secondary diseases and other environmental factors that affect the absorption, distribution, metabolism and excretion of drugs and may lead to adverse reactions. These reactions are responsible for millions of hospitalizations and thousands of deaths each year in the United States. Identification and characterization of a large number of genetic polymorphisms (biomarkers) in metabolizing enzymes and transporters of drugs can provide a thorough understanding of the mechanisms of inter-individual differences in drug response. The use of new molecular technologies, in particular genome sequencing, diagnosis for assessing the genetic profile and assessing biomarkers of disease open new paths to individualize each patient's treatment plan, optimizing it’s results. This treatment schedule, while decreasing the number of adverse reactions avoids exposing the patient to a long-term therapy based on trial and error. For patients, personalized medicine holds the promise of more effective therapies with fewer side effects, and may thus spare the prospect of a treatment with significant adverse effects and little or no therapeutic effect Pharmacogenetics and pharmacogenomics are two areas that have emerged to investigate the individual variability in response to drugs. The pharmaceutical industry uses increasingly techniques related to pharmacogenetics and pharmacogenomics and the information that follows them to the process of drug development, promoting the prescription of appropriate medication in the right dose for each patient.
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Hautala, A. (Arto). "Effect of physical exercise on autonomic regulation of heart rate." Doctoral thesis, University of Oulu, 2004. http://urn.fi/urn:isbn:9514273354.
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Abstract
Regular aerobic training has been suggested to protect the heart by increasing cardiac vagal activity. The aims of this study were to evaluate the autonomic regulation of heart rate (HR) during and after exercise, during aerobic training interventions and to study the association between autonomic regulation and the training response in healthy male subjects. HR variability assessment was used to study the effects of exercise on autonomic regulation of HR.
The whole study population consisted of 70 volunteer male subjects (age 36 ± 10 years). The recovery of the autonomic nervous system after prolonged exhaustive exercise was studied in a group of 10 subjects. The training interventions included 51 subjects. The effects of training volume on autonomic regulation were assessed (n = 46) during a controlled eight-week training intervention. The association between training and autonomic regulation was studied (n = 24) during a ten-month period of home-based training based on the American College of Sports Medicine recommendations. Finally, the association between autonomic regulation and the individual training response was analysed (n = 51) after eight weeks of controlled training.
The recovery rate of vagally mediated high-frequency (HF) power of HR variability after prolonged exhaustive exercise was associated with physical fitness (r = -0.71, P < 0.016). Moderate (3 hours/week) and high-volume (6 hours/week) aerobic training results in a similar increase in HR variability indices. HF power increased from 6.19 ± 1.02 to 6.76 ± 0.96 ln ms2 (P < 0.001) and from 6.61 ± 1.01 to 7.12 ± 0.92 ln ms2 (P < 0.001) after moderate and high-volume training, respectively. During the home-based training program, the changes in HF power were associated with the changes in the fitness (r = 0.44, P < 0.05), body mass index (r = -0.44, P < 0.05) and the amount of training (r = 0.41, p < 0.05). Finally, a significant correlation was observed between the training response and the baseline HF power (r = 0.52, P = 0.001). HF power accounted for 27 % of the change as an independent predictor of the aerobic training response.
In conclusion, a highly controlled aerobic training intervention of eight weeks, including six 30-min sessions a week at an intensity of 70–80 % of maximum HR, is a sufficient intervention to increase cardiac vagal outflow and the offered home-based training according the current guidelines maintains the high cardiac vagal outflow. Secondly, high vagal activity at baseline is associated with the improvement in aerobic fitness caused by aerobic training, suggesting that the cardiovascular autonomic function is an important determinant of the response to aerobic training.
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Hauschild, Luciano. "MODELAGEM INDIVIDUAL E EM TEMPO REAL DAS EXIGÊNCIAS NUTRICIONAIS DE SUÍNOS EM CRESCIMENTO." Universidade Federal de Santa Maria, 2010. http://repositorio.ufsm.br/handle/1/4315.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorTwo studies were realized with the objective (i) to describe and to establish the limitations of the empirical and factorial methods used to estimate nutritional requirements and (ii) develop a mathematic model able to estimate the daily nutrient requirements of individual pigs in real time. For this purpose, in the first study a systematic analysis was carried out on the lysine - net energy (Lys:NE) ratios estimated through the empirical and factorial methods with the help of the InraPorc® growth model. Based on analysis of data on 68 pigs, Lys:NE ratios were estimated for three feeding phases. In the empirical method, population response was determined on eleven different Lys:NE ratios. Response was evaluated with ADG and FCR being used as variables. In the factorial method, the Lys:NE ratio for each animal was estimated through model inversion. In the second study, it was developed a model which includes an empirical and mechanistic component. The empirical component estimates the daily feed intake (DFI) and BW based on individual pig information collected in real time. The mechanistic component estimates the optimal concentration of amino acid that must be offered to pigs to meet their requirements. In establishing limitations, it was observed that the factorial method, when applied to the mean animal, does not allow for estimation of the Lys:NE ratio to maximize response in a heterogeneous population which is to be fed over a long period of time. In the empirical method, while these aspects are considered, the estimated response is fixed and cannot be used for other intervals or populations. The empirical component results indicate that the DFI and BW trajectories of individual pigs fed ad libitum could be predicted 1 (DFI) or 7 days (BW) ahead with an mean absolute percentage error of 12 and 2 %, respectively. The mechanistic component estimates the optimal lysine to net energy ratio with reasonable between ‐ animal (average CV = 7 %) and over ‐ time variation (average CV = 14 %). Thus, the nutrient requirements estimated by the model are animal and time dependents and they follow in real ‐ time the individual DFI and BW growth patterns. The results from first study confirm that the two methods needs lead to different recommendations and have important limitations that should be considered when used to optimize the response of an individual or a population of pigs. The model developed is part of the development of precision feeding techniques allowing the right amount of feed with the right composition at the right time to be provided to each pig in the herd.
Dois estudos foram realizados com o objetivo de (i) descrever e estabelecer as limitações dos métodos empírico e fatorial utilizados para estimar as exigências e (ii) desenvolver um modelo matemático de estimação das exigências individuais e em tempo real para suínos. Para atender esses objetivos, no primeiro estudo uma análise sistemática foi realizada nas relações de lisina e energia líquida (Lis:EL) estimadas pelos métodos empírico e fatorial com o auxilio do modelo InraPorc®. Baseado na análise de dados de 68 suínos, as relações de Lis:EL foram estimadas para três fases alimentares. No método empírico, a resposta da população foi determinada através de onze diferentes relações de Lis:EL. A resposta da população foi avaliada através do ganho de peso e conversão alimentar. No método fatorial, a relação de Lis:EL para cada animal foi estimada através da inversão do modelo InraPorc. No segundo estudo, foi desenvolvido um modelo o qual é composto de um componente empírico e mecanicista. O componente empírico estima o consumo diário de alimento (CDA) e peso vivo (PV) baseado em informações individuais coletadas em tempo real. O componente mecanicista estima a concentração ideal em aminoácidos necessária para atender as exigências de cada indivíduo. Na avaliação dos métodos, foi observado que o método fatorial não permite estimar a relação de Lis:EL para maximizar a resposta de uma população heterogênea alimentada com uma única dieta durante um longo período. No método empírico, embora esses aspectos sejam considerados, a resposta estimada é fixa e não pode ser utilizada para outros intervalos ou populações. No modelo desenvolvido, os resultados do componente empírico demonstraram que a trajetória de CDA e o PV dos animais alimentados ad libitum podem ser estimadas com antecedência de 1 (CDA) ou 7 dias (PV) com erro absoluto médio de 12 e 2 %, respectivamente. O componente mecanicista estimou relações de Lis:EL as quais apresentaram uma razoável variabilidade entre animais (CV médio = 7 %) e no tempo (CV médio = 14 %). No modelo, as exigências nutricionais estimadas são, portanto, animal e tempo dependentes. Adicionalmente, o modelo segue em tempo real as trajetórias de CDA e PV dos animais. Os resultados do primeiro estudo confirmam que os dois métodos determinam diferentes recomendações e apresentam limitações que deveriam ser consideradas quando utilizados para otimizar respostas de populações ou indivíduos. O modelo desenvolvido é parte integrante de um sistema de alimentação de precisão que visa fornecer uma quantidade adequada de nutrientes para cada indivíduo em tempo real.
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Barnett, Kimberly A. "Is Variability in Inhibition-Related Neural Activation After Sleep Restriction Associated with Eating Behavior in Adolescents?" BYU ScholarsArchive, 2021. https://scholarsarchive.byu.edu/etd/9091.
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The primary aim of the present study was to evaluate whether intra-individual variability in inhibition-related neural activation in response to sleep restriction is associated with eating behavior in adolescents aged 12-18 years. In addition, the potential moderating effects of sex and body mass index on the association between sleep and variability in neural activation were examined. This study employed a within-subjects crossover design that randomized subjects to both a 5 hours per night (sleep restricted) and 9 hours per night (well-rested) sleep condition for 5 nights, with experimental conditions separated by four weeks. On the 6th day of each study phase participants completed a 24-hour diet recall and a food-related inhibitory go/no-go task while undergoing functional magnetic resonance imaging. Repeated measures multilevel models examined individual differences attributable to sleep duration and a series of separate multivariate analysis of variance models examined the effect that vulnerability to sleep restriction has on eating behavior as well as the moderating impact of sex and weight status. Findings suggest that adolescents who exhibited greater efficiency in inhibitory and reward-related neural activation when sleep restricted demonstrated less pronounced decrements in neural activation when sleep restricted relative to when they were well-rested. These findings suggest that the effect of sleep restriction on inhibitory control may differ between individuals such that there are individuals who appear able to sustain inhibitory control comparable to when they are well-rested while other individuals show marked declines in executive functioning-related neural activation when sleep restricted. Results from separate exploratory models including regions of interest associated with reward valuation and across the whole brain were consistent with these findings. We also found that the effect of vulnerability to sleep restriction on inhibitory efficiency in the right inferior parietal lobule (R - IPL) and right middle frontal gyrus (R - MFG) differed by sex and was predictive of differences in overall eating behavior and sugar intake, respectively, when sleep restricted compared to well-rested. In addition, vulnerability in the inhibitory network was predictive of differences in individual eating behavior (i.e., total calories, added sugar, sugar, and total fat) for males and females across conditions. This finding demonstrates there is significant variability in the impact that sleep restriction has on inhibitory efficiency in adolescence relative to when they are well-rested, and vulnerability to inhibitory efficiency appears to effect male and female adolescent's dietary behaviors differently when they obtain insufficient sleep. Vulnerability to inhibitory efficiency when sleep restricted compared to well-rested may cause males and females to consume more energy dense foods when they obtain insufficient sleep and also differs for males and females irrespective of their sleep duration. Given the pervasiveness of chronic sleep restriction in adolescence, males who are unable to counter the effect that insufficient sleep has on palatable foods may be at greatest risk of obesity.
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Maxwell, Lara J. "Assessment of Intra- and Inter-individual Variability of Outcome Measures in Ankylosing Spondylitis and the Efficacy and Adverse Effects of Anti-TNF Therapy." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20093.
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Ankylosing spondylitis (AS) is a chronic, inflammatory rheumatic disease that has a highly variable disease course. Three biologic agents, adalimumab, etanercept, and infliximab, have been developed for the treatment of AS. We conducted three studies: 1) an exploratory analysis of a year-long longitudinal dataset to gain insight into the variability of disease activity, physical function, and well-being and to explore the relationship between these outcome measures; 2) a systematic review of the available evidence for the efficacy of biologic treatment; 3) a systematic review of potential adverse effects of this treatment. We found that repeated measures of disease activity, function and well-being fluctuate considerably between patients, with complex patterns occurring over time within patients. There was mostly high quality evidence that these biologics are efficacious against placebo. We did not find evidence of an increase in serious adverse events or serious infections from short-term randomized controlled trials.
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Richard, Quentin. "Hétérogénéité individuelle, variabilité temporelle et structure spatiale comme sources de variation démographique chez les grands herbivores de montagne." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAV070/document.
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Dans l’hémisphère Nord, les populations de grands herbivores ont connu ces dernières décennies des modifications environnementales majeures, liées d’une part à l’augmentation importante de leur densité, et d’autre part aux changements globaux qui affectent leur habitat (notamment réchauffement climatique, modification des activités humaines, et fragmentation de l’habitat). Mieux comprendre comment ces espèces vont adapter leurs stratégies d’histoire de vie pour répondre à ces modifications est une question majeure de l’écologie des populations, et une étape nécessaire pour pouvoir adapter leur gestion aux enjeux environnementaux et sociétaux actuels. C’est dans ce contexte que nous avons étudié quelles étaient les sources de variation des tactiques de survie et de reproduction chez trois espèces de grands herbivores de montagne (l’isard Rupicapra pyreneica, le chamois Rupicapra rupicapra, et le mouflon méditerranéen Ovis gmelini musimon × Ovis sp.). A partir de suivis longitudinaux par capture-marquage-recapture (CMR) nous nous sommes plus particulièrement focalisés sur le rôle de l’hétérogénéité individuelle latente, de la variabilité climatique et de la structuration spatiale sur les paramètres démographiques.Ce travail s’est appuyé sur l’utilisation de modèles de mélange et d’une combinaison innovante du robust-design et des modèles multi-événements pour analyser des données démographiques collectées à différentes échelles spatio-temporelles. L’hétérogénéité individuelle s’est avérée être une composante majeure de la démographie des 3 espèces étudiées, avec l’identification chez le mouflon et l’isard de femelles aux performances reproductives contrastées, et l’existence chez le chamois de différences de survie entre individus liées à la qualité de l‘habitat occupé. Ces modèles ont aussi permis de révéler une augmentation de l’investissement reproducteur en fin de vie chez les femelles de mouflon au détriment de leur survie et d’étudier chez les femelles d’isard les différentes phases de l’effort reproducteur, de la gestation au sevrage, pour mettre en évidence que seule la lactation a un coût sur la reproduction suivante. Nos résultats ont également mis en exergue le rôle prépondérant du climat hivernal et printanier sur les paramètres démographiques des 3 espèces, tout en confirmant que ces effets sont souvent spécifiques à la population et au site étudiés. Cette étude montre également que l’isard et le mouflon, bien que relativement comparables en termes de taille, de traits écologiques, et de position phylogénétique, adoptent des stratégies d’histoire de vie contrastées.Au final, nos résultats soulignent donc l’importance des études démographiques comparatives à plusieurs niveaux d’organisation (inter-espèces, inter-population, intra-population), pour mieux comprendre le devenir des espèces de grands herbivores face aux perturbations environnementalesIn Northern hemisphere, populations of large herbivores have to cope with major environmental modifications linked to the increase of their density and to global change which strongly impacts their habitat (climate change, modification of human activities and habitat fragmentation). Understanding how these species adjust their life history strategies in response to such modifications is central for population ecology and for management issues. In this context, this work aimed to identify the sources of variation of survival and reproductive tactics in 3 species of mountain ungulate (Pyrenean chamois Rupicapra pyreneica, Alpine chamois Rupicapra rupicapra, and Mediterranean mouflon Ovis gmelini musimon × Ovis sp.). Using capture-mark-recapture monitoring we specifically investigated the role of individual heterogeneity, climate change, and spatial heterogeneity in shaping vital rates.This work relied on mixture models and an innovative combination of robust-design into a multi-events framework to explore demographic data collected at different spatio-temporal scales. Fixed heterogeneity appeared as a major demographic component in the 3 studied species by highlighting in mouflon and Pyrenean chamois two groups of females with contrasted reproductive performance, and by providing evidence in chamois of among-females differences in survival rates linked to the quality of their habitat. These models allowed us to provide evidence for the terminal investment hypothesis in female mouflon and to decompose reproductive effort in females of Pyrenean chamois from gestation to weaning, to unveil that lactation only led to cost on subsequent reproduction. Our results also highlighted the major influence of winter and spring climatic conditions on demographic parameters in the 3 studied species, and confirmed the general trend that climate effects are often species- and site-specific. Our findings provided evidence that Pyrenean chamois and mouflon evolved contrasted life history strategies, although both species share strong similarities in terms of body mass, ecological traits and phylogenetic position.Finally, our work stresses the importance of conducting comparative demographic studies, based on longitudinal monitoring of marked individuals, at inter-specific, inter-population and within population levels, to better understand and predict the future of large herbivores populations in the current context of global changes
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Britton, Oliver Jonathan. "Combined experimental and computational investigation into inter-subject variability in cardiac electrophysiology." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:6299240d-0528-4662-8e1f-5025f39e730f.
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The underlying causes of variability in the electrical activity of hearts from individuals of the same species are not well understood. Understanding this variability is important to enable prediction of the response of individual hearts to diseases and therapies. Current experimental and computational methods for investigating the behaviour of the heart do not incorporate biological variation between individuals. In experimental studies, experimental results are averaged together to control errors and determine the average behaviour of the studied organism. In computational studies, averaged experimental data is usually used to develop models, and these models therefore represent a 'typical' organism, with all information on variability within the species having been lost. In this thesis we develop a methodology for modelling variability between individuals of the same species in cardiac cellular electrophysiology, motivated by the inability of traditional computational modelling approaches to capture experimental variability. A first study is conducted using traditional modelling approaches to investigate potentially pro-arrhythmic abnormalities in rabbit Purkinje fibres. A comparison with experimental recordings highlights their wide variability and the inability of existing computer modelling approaches to capture it. This leads to the development of a novel methodology that integrates the variability observed in experimental data with computational modelling and simulation, by building experimentally-calibrated populations of computational models, that collectively span the variability seen in experimental data. We apply this methodology to construct a population of rabbit Purkinje cell models. We show that our population of models can quantitatively predict the range of responses, not just the average response, to application of the potassium channel blocking drug dofetilide. This demonstrates an important potential application of our methodology, for predicting pro-arrhythmic drug effects in safety pharmacology. We then analyse a data set of experimental recordings from human ventricular tissue preparations, and use this data to develop a population of human ventricular cell models. We apply this population to study how variability between individuals alters the susceptibility of cardiac cells to developing drug-induced repolarisation abnormalities. These abnormalities can increase the chance of fatal arrhythmias, but the mechanisms that determine individual susceptibility are not well-understood.
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Bonnet-Lebrun, Anne-Sophie. "Intraspecific variation in environmental and geographic space use : insights from individual movement data." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/275584.
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Species’ ranges arise from the interplay between environmental preferences, biotic and abiotic environmental conditions, and accessibility. Understanding of – and predictive models on – species distributions often build from the assumption that these factors apply homogenously within each species, but there is growing evidence for individual variation. Here, I use movement data to investigate individual-level decisions and compromises regarding the different costs and benefits influencing individuals’ geographic locations, and the species-level spatial patterns that emerge from these. I first developed a new method that uses tracking data to quantify individual specialisation in geographic space (site fidelity) or in environmental space (environmental specialisation). Applying it to two species of albatrosses, I found evidence of site fidelity but weak environmental specialisation. My results have implications for how limited research efforts are best-targeted: if animals are generalists, effort are best spent by understanding in depth individual patterns, i.e., better to track fewer individuals for long periods of time; whereas if animals tend to be specialists, efforts should be dedicated to tracking as many individuals as possible, even if for shorter periods. I then investigated individual migratory strategies and their drivers in nine North American bird species, using ringing/recovery data. I found latitudinal redistribution of individuals within the breeding and non-breeding ranges that generally did not follow textbook patterns (‘chain migration’ or ‘leapfrog migration’). Migratory individuals tend to trade off the benefits of migration (better tracking of climatic niche; better access to resources) and its costs (increasing with migratory distance). I found that birds are more likely to remain as residents in areas with warmer winter temperatures, higher summer resource surpluses and higher human population densities (presumably because of a buffering effect of urban areas). Overall, my results highlight the importance of considering individual variation to understanding the ecological processes underpinning species’ spatial patterns.
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Li, Xia [Verfasser]. "Application of population, physiologically based, and semi-physiological pharmacokinetic modeling to assess sources of pharmacokinetic variability in individual drugs / Xia Li." Bonn : Universitäts- und Landesbibliothek Bonn, 2020. http://d-nb.info/121830118X/34.
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Balieiro, Flora Silveira. "Comunicação acústica do lobo-guará: evidências de discriminação individual via playback de aulidos." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/59/59134/tde-11052016-161038/.
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O canal acústico é um sistema de sinalização de longo alcance eficiente que pode ser especialmente efetivo para animais com hábitos crepusculares/noturnos. O lobo-guará é um canídeo ameaçado com hábitos crepusculares/noturnos que, no senso comum, é visto como uma espécie solitária. De fato, seria melhor definida como uma espécie gregária, uma vez que macho e fêmea dividem o mesmo território e a distância espacial entre eles varia de acordo com o período reprodutivo da fêmea. O aulido do lobo-guará é uma vocalização de longa distância que funciona como um mecanismo para aumentar a distância espacial entre coespecíficos, bem como para permitir casais de encontrarem um ao outro. Variações individuais nesta vocalização foram relatadas, mas a possibilidade de que elas possam ser percebidas e usadas pela espécie nunca foi testada. Deve-se esperar que essas variações individuais possam ser percebida, pois somente neste cenário seria plausível para o aulido ter a dupla função mencionada acima. Se esta variabilidade individual não é percebida pelos coespecíficos, a eficiência desta vocalização a longas distâncias seria comprometida, já que o ouvinte não seria capaz de identificar se o remetente é o seu parceiro reprodutivo ou um possível rival. Em nosso estudo usamos playbacks para testar se essas variações individuais podem ser percebidas por lobos em cativeiro e concluimos que eles podem. Pelo que conhecemos, esta é a primeira vez se demonstra que o lobo-guará é capaz de discriminar entre aulidos emitidos por diferentes indivíduosThe acoustic channel is an efficient long-distance signaling system that may be especially effective for animals with crepuscular/nocturnal habits. The maned wolf is a threatened canid with crepuscular/nocturnal habits that is thought to be a solitary species in common sense. As a matter of fact, it would be better defined as a gregarious species, since male and female share the same wide territory and the spatial distance between them varies according to the females reproductive period. The maned wolfs extended-bark is a long-distance vocalization that functions as a mechanism to increase spatial distance among conspecifics as well as to enable pair-mates to find each other. Individual variations in this vocalization have been reported, but the possibility that they can be perceived and used by the species has never been tested. One should expect these individual variations to be perceived by the species, since only in this scenario it would be plausible for the extended-bark to have the dual function stated above. If this individual variability is not perceived by conspecifics, the efficiency of this vocalization at long distances, at least for the hypothesized functions, would be compromised, as the hearer would not be able to identify if the sender is its reproductive partner or a possible rival. In our study we used playbacks to test if these individual variations can be perceived by captive wolves and have concluded that they can. To our knowledge, this is the first time it has been demonstrated that the maned wolf is capable of discriminating among extended-barks of different individuals
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Schmitt, Sylvain. "Ecological genomics of niche exploitation and individual performance in tropical forest trees." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0247.
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Les forêts tropicales abritent la plus grande diversité d'espèces au monde, un fait qui reste en partie inexpliqué et dont l'origine est sujette à débat. Même à l'échelle de l'hectare, les forêts tropicales abritent des genres riches en espèces, avec des espèces d’arbres étroitement apparentées qui coexistent en sympatrie. En raison de contraintes phylogénétiques, on s'attend à ce que les espèces étroitement apparentées possèdent des niches et des stratégies fonctionnelles similaires, ce qui questionne les mécanismes de leur coexistence locale. Les espèces étroitement apparentées peuvent former un complexe d'espèces, composé d’espèces morphologiquement similaires ou qui partagent une importante proportion de leur variabilité génétique en raison d'une ascendance commune récente ou d'hybridation, et qui peut résulter d'une radiation écologique adaptative des espèces selon des gradients environnementaux. Malgré le rôle clé des complexes d'espèces dans l'écologie, la diversification et l'évolution des forêts néotropicales, les forces éco-évolutives qui créent et maintiennent la diversité au sein des complexes d'espèces néotropicales restent peu connues. Nous avons exploré la variabilité génétique intraspécifique comme un continuum au sein de populations structurées d'espèces étroitement apparentées, et mesuré son rôle sur la performance individuelle des arbres à travers la croissance dans le temps, tout en tenant compte des effets d'un environnement finement caractérisé au niveau abiotique et biotique. En combinant des inventaires forestiers, des données topographiques, des traits fonctionnels foliaires et des données de capture de gènes dans la station de recherche de Paracou, en Guyane Française, nous avons utilisé la génomique des populations, les analyses d'associations environnementales et génomiques, et la modélisation Bayésienne sur les complexes d'espèces Symphonia et Eschweilera clade Parvifolia. Nous avons montré que les complexes d'espèces d'arbres couvrent l’ensemble des gradients locaux de topographie et de compétition présents dans le site d'étude alors que la plupart des espèces qui les composent présentent une différenciation de niche marquée le long de ces mêmes gradients. Plus précisément, dans les complexes d'espèces étudiés, la diminution de la disponibilité en eau, par exemple depuis les bas-fonds jusqu’aux plateaux, a entraîné une modification des traits fonctionnels foliaires, depuis des stratégies d'acquisition à des stratégies conservatrices, tant entre les espèces qu'au sein de celles-ci. Les espèces de Symphonia sont génétiquement adaptées à la distribution de l'eau et des nutriments, elles coexistent donc localement en exploitant un large gradient d'habitats locaux. Inversement, les espèces d'Eschweilera sont différentiellement adaptées à la chimie du sol et évitent les habitats les plus humides et hydromorphes. Enfin, les génotypes individuels des espèces de Symphonia sont différentiellement adaptés pour se régénérer et croître en réponse à la fine dynamique spatio-temporelle des trouées forestières, avec des stratégies adaptatives de croissance divergentes le long des niches de succession. Par conséquent, la topographie et la dynamique des trouées forestières entraînent des adaptations spatio-temporelles à fine échelle des individus au sein et entre les espèces des complexes d'espèces Symphonia et Eschweilera. Je suggère que les adaptations à la topographie et à la dynamique des trouées forestières favorisent la coexistence des individus au sein et entre les espèces des complexes d'espèces, et peut-être plus généralement entre les espèces d'arbres de forêts matures. Dans l'ensemble, je soutiens le rôle primordial des individus au sein des espèces dans la diversité des forêts tropicales, et suggère que nous devrions élaborer une théorie de l'écologie des communautés en commençant par les individus, car les interactions avec les environnements se produisent après tout au niveau de l’individuTropical forests shelter the highest species diversity worldwide, a fact that remains partly unexplained and the origin of which is subject to debate. Even at the hectare-scale, tropical forests shelter species-rich genera with closely-related tree species coexisting in sympatry. Due to phylogenetic constraints, closely related species are expected to have similar niches and functional strategies, which raises questions on the mechanisms of their local coexistence. Closely related species may form a species complex, defined as morphologically similar species that share large amounts of genetic variation due to recent common ancestry and hybridization, and that can result from ecological adaptive radiation of species segregating along environmental gradients. Despite the key role of species complexes in Neotropical forest ecology, diversification, and evolution, little is known of the eco-evolutionary forces creating and maintaining diversity within Neotropical species complexes. We explored the intraspecific genomic variability as a continuum within structured populations of closely related species, and measured its role on individual tree performance through growth over time, while accounting for effects of a finely-characterized environment at the abiotic and biotic level. Combining tree inventories, LiDAR-derived topographic data, leaf functional traits, and gene capture data in the research station of Paracou, French Guiana, we used population genomics, environmental association analyses, genome-wide association studies and Bayesian modelling on the tree species complexes Symphonia and Eschweilera clade Parvifolia. We showed that the species complexes of Neotropical trees cover all local gradients of topography and competition and are therefore widespread in the study site whereas most of the species within them exhibit pervasive niche differentiation along these same gradients. Specifically, in the species complexes Symphonia and Eschweilera clade Parvifolia, the decrease in water availability due to higher topographic position, e.g., from bottomlands to plateaus, has led to a change in leaf functional traits from acquisitive strategies to conservative strategies, both among and within species. Symphonia species are genetically adapted to the distribution of water and nutrients, hence they coexist locally through exploiting a broad gradient of local habitats. Conversely, Eschweilera species are differentially adapted to soil chemistry and avoid the wettest, hydromorphic habitats. Last but not least, individual tree genotypes of Symphonia species are differentially adapted to regenerate and thrive in response to the fine spatio-temporal dynamics of forest gaps with divergent adaptive growth strategies along successional niches. Consequently, topography and the dynamics of forest gaps drive fine-scale spatio-temporal adaptations of individuals within and among distinct but genetically connected species within the species complexes Symphonia and Eschweilera clade Parvifolia. Fine-scale topography drives genetic divergence and niche differentiation with genetic adaptations among species, while forest gap dynamics maintains genetic diversity with divergent adaptive strategies within species. I suggest that adaptations of tree species and individuals to topography and dynamics of forest gaps promote coexistence within and among species within species complexes, and perhaps among mature forest tree species outside species complexes. Overall, I defend the primordial role of individuals within species in tropical forest diversity, suggesting that we should develop a theory of community ecology starting with individuals, because interactions with environments happen after all at the individual level
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Tan, Xueli. "Interactionality of trait-state music preference, individual variability, and music characteristics as a multi-axis paradigm for context-specific pain perception and management." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/5860.
Full textAbstract:
The purposes of this 3-phase study were 1) to identify salient individual variabilities and music characteristics associated with music therapy interventions for pain management, 2) to explore current pain management practices of music therapists, 3) to delineate any differences in general musical taste (trait) and context-specific music preference (state), as well as preferred music characteristics in healthy adults and cancer patients, 4) to investigate the contributions of individual variabilities, personality, behavioral coping styles, and pain levels in predicting changes from trait to state preferences and preferred music characteristics under various pain conditions, and 5) to investigate any differences in music preference patterns between healthy adults and cancer patients.
In Phase I, 97 music therapists completed an online questionnaire to provide quantitative and qualitative data regarding the saliency of individual variabilities and music characteristics in determining the choice of music for pain management interventions, as well as their current practices with adult populations in clinical settings. In Phase II, 50 healthy adults (33 females, 17 males) ranging in age from 40 to 70 years (M = 57.04 ± 7.99) completed a battery of tests and questionnaires, including a Participant Intake Form (demographic information, music background, listening habits), an adapted Short Test of Music Preference – Revised (STOMP-R-A), a Music Characteristics Test, the Miller Behavioral Style Scale – abbreviated (MBSS-abbreviated), and the NEO Five-Factor Inventory-3 (NEO-FFI-3). The STOMP-R-A measured the participants’ trait and state preferences for 23 music genres. The Music Characteristics Test involved a music listening portion for participants to rate their preferences for various music characteristics. The MBSS-abbreviated measured behavioral coping styles and the NEO-FFI-3 measured the five dimensions of personality. In Phase III, 35 cancer patients (24 females, 11 males) ranging in age from 42 to 70 years (M = 57.71 ± 7.07) completed the same measurement tools as the ones used in Phase II, as well as the Short-Form McGill Pain Questionnaire–2 (SF-MPQ-2), which measured ratings for chronic, acute, and neuropathic pain.
A one-way analysis of variance was used to test for response bias amongst the music therapists in Phase I. No response bias was found. Responses were reported as sums and converted to percentages of respondents for each selected response. Qualitative responses were analyzed using open coding and thematic development techniques. An intercoder was recruited to authenticate reliability for the qualitative findings. Music therapists identified age, ethnicity, culture, and religious preferences as important individual variabilities, and tempo, rhythmic complexity, and dynamics as salient music characteristics in their ratings. The results from Phase I informed the methodology for the next two phases of this study.
Participants in Phases II and III were tested individually. The paired t-test was used to determine differences between trait and state music preferences across all 23 genres. The results indicated significant decreases from trait to state music preferences across music genres in both healthy adult and cancer patient groups. Calculations of the chi-square statistic and the McNemar’s test were used to detect differences between trait music preference and state music preference specific to each of the 23 genres. Multiple logistic regression analysis was used to examine the contributions of demographic factors, personality, behavioral coping style, and pain to changes from trait to state preferences and preferred music characteristics under four pain conditions. In Phase II, age, gender, and neuroticism predicted changes in trait-state preference for music genres; and gender and behavioral coping styles predicted changes in preferences for music characteristics under low-acute, high-acute, low-chronic, and high-chronic pain conditions. In Phase III, neuroticism predicted changes in trait-state preference for music genres; and age predicted changes in preferences for music characteristics under the four pain conditions.
The independent t-test was used to determine differences between healthy adults’ and cancer patients’ ratings of the importance of music, music background, and music listening habits. No significant differences were found between the two groups. Healthy adults and cancer patients were most familiar with country music and rated oldies and rock as their most preferred music genres. Healthy adults reported familiarity with and preferences for greater number of genres compared to cancer patients. In general, both groups indicated decreased preferences for music under pain conditions. The findings from this study emphasized the importance of considerations for the interactions of trait-state music preferences, individual variabilities, and music characteristics as a paradigm for context-specific pain management in adult clinical settings.
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Cipolat, Gotet Claudio. "Genetic and phenotypic variability of milk coagulation properties, cheese yield, nutrients recoveries and cheese sensory properties assessed on individual milk of Brown Swiss cows." Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3423109.
Full textAbstract:
Milk cheese-making ability have received great interest from the dairy industry in the worldwide increasing of the amount of milk used for cheese production. In recent years, scientific research was mainly occupied to identify and study phenotypic and genetic variability of milk coagulation properties. The relationship between these traits and cheese yield is not entirely clear. Cheese yield, milk nutrients recoveries in the curd and whey losses represent indices that defines the efficiency of the cheese-making process and are used as tools for economic control in the dairies. To our knowledge, any studies have not yet been proposed on the assessing of yield and quality traits of individual cheese variability using bovine milk. These traits are influenced by environmental and genetic factors.
In the present thesis quality cheese-making traits of milk from individual cows of the Brown Swiss were assessed. In particular, this study has focused on the milk coagulation properties, the cheese yield, the nutrients recoveries in the curd and, finally, the quality ( chemical components, physical traits and sensory properties) of cheese.
Milk coagulation properties were compared through a traditional mechanical device and a near-infrared optical device. This comparison of MCP traits (RCT, k20, a30, a45) has emphasized phenotypic and genetic differences between measures obtained by the two devices, especially for samples coagulating after 30 minutes (NC samples) from start analysis. Rennet coagulation time (RCT) was the trait presenting less differences when assesses by a different instrument. Extending the analysis the analysis by either instruments allowed to: obtain RCT for all samples analysed, estimate a new curd firmness trait (a45; the width of the resulting graph after 45 min from the rennet addition), estimate the heritability of k20 and a45 and genetic correlations with the milk production and qualitative traits. The results obtained suggested the use of the optical instrument for the assessment of the first phase of coagulation process where the chemical-physical changes of the milk are not visible.
Cheese yield was estimated by developing an individual model-cheese production procedure 1500 ml of milk per sample. The described model cheese-producing procedure and the obtained results provide new insight into variation and relationships among different cheese yield (curd, dry matter and water) and recovery (protein, fat, dry matter and energy) traits at the individual level.
The results showed high milk quality of milk Brown Swiss breed presenting on average a cheese yield of 15%. Measures of nutrient recoveries (protein, fat, total solids and energy) were computed exhibiting a great variability. It has been observed that the yield is not only influenced by the milk dry matter but also by the milk water. From a genetic point of view, heritability has been estimated for cheese yield (of the curd, the dry matter and water) and the recovery of nutrients in the curd (protein, fat, dry matter and energy) and the results have shown a certain importance of genetic factors on the variability of these traits. Clearly, additional research on this topic is warranted, especially in terms of assessing the genetic background of these traits and the methods for their indirect prediction.
Finally, it was evaluated the qualitative traits and sensory properties of cheeses produced at the individual level (from each cow). The results showed a great variability of these traits at individual level. From the variation factors considered in this study, stage of lactation appeared to be important reflecting the changes in milk composition, while order of parity did not show any significant relationship with the analysed traits. cheese composition and few sensory properties (related to the cheese texture), were influenced by the cheese yield of milk. Collection of these data at the individual level will also allow to estimate genetic parameters of these traits.L’attitudine del latte alla caseificazione rappresenta un argomento che desta molto interesse per l’aumento della quota prodotta della materia prima destinata alla produzione di formaggio. Negli ultimi anni la ricerca scientifica si è occupata soprattutto della determinazione ed identificazione delle proprietà di coagulazione del latte atte ad essere impiegate come fattore di valutazione e, di riflesso, come possibile carattere obiettivo di selezione nelle vacche da latte. Ad oggi, la relazione tra le proprietà di coagulazione del latte e la resa casearia non è del tutto chiara. La resa in formaggio rappresenta l’indice che definisce l’efficienza del processo di caseificazione ed è per questo utilizzato come strumento di controllo economico nei caseifici. Non sono stati ancora proposti degli studi che vadano a porre l’attenzione su fenotipi legati alla resa casearia ed alla qualità del formaggio prodotto dal latte individuale di specie bovina. Tali caratteristiche variano in funzione di una serie di fattori sia di natura ambientale che genetica. Con la presente tesi sono stati presi in considerazione i caratteri che definiscono l’attitudine casearia del latte individuale di vacche di razza Brown Swiss. In particolare, l’indagine scientifica ha riguardato le proprietà di coagulazione del latte, la resa casearia e le perdite nel siero dei componenti del latte ed, infine, la qualità del formaggio tramite la analisi fisico-chimica e sensoriale. La valutazione delle proprietà di coagulazione del latte ha previsto l’utilizzo di due strumenti che presentano tecnologie di funzionamento differenti (meccanico ed ottico). Il confronto degli stessi caratteri (RCT, k20, a30, a45) ottenuti con i due strumenti ha sottolineato differenze sia da un punto di vista fenotipico che da un punto di vista genetico, soprattutto per i campioni di latte coagulanti dopo 30 minuti dall’inizio dell’analisi. Il tempo di coagulazione (RCT) è stato il parametro in cui sono state riscontrate minori differenze tra i risultati ottenuti dai due differenti strumenti. L’aumento della durata dell’analisi a 90 minuti ha permesso di: ottenere l’RCT per tutti i campioni analizzati, stimare un nuovo parametro di consistenza del coagulo a 45 minuti dall’inizio dell’analisi (a45), determinare l’ereditabilità e le correlazioni genetiche con i caratteri qualitativi del latte per il k20 ed anche per l’a45. I risultati ottenuti suggeriscono l’eventuale utilizzo dello strumento ottico per la valutazione delle primissime fasi del processo di coagulazione dove i cambiamenti chimico-fisici del latte non sono visibili. La resa casearia è stata determinata mettendo a punto una procedura di micro caseificazione utilizzando 1500 ml di latte per campione. I risultati ottenuti hanno evidenziato un’elevata qualità del latte di razza bruna con una resa media a fresco del 15% circa. È stato possibile stimare il recupero nella cagliata dei componenti del latte: questi caratteri non sono risultati costanti ma è stata osservata una certa variabilità sulla base dei fattori presi in considerazione nel presente studio (stadio di lattazione, ordine di parto, produzione di latte). È stato osservato che la resa non è influenzata solamente dalla materia utile del latte ma anche dall’acqua. Da un punto di vista genetico, è stata stimata per la prima volta nel latte bovino, l’ereditabilità della resa casearia (della cagliata, della sostanza secca e dell’acqua) e del recupero di nutrienti nella cagliata (proteina, grasso, sostanza secca ed energia). I risultati ottenuti hanno evidenziato la presenza di una rilevante componente genetico additiva degli animali, potenzialmente sfruttabile per finalità selettive. Infine, sono state valutate le caratteristiche qualitative ed organolettiche dei formaggi prodotti a livello individuale. Dallo studio delle potenziali fonti di variazione è emerso che lo stadio di lattazione risulta essere un fattore altamente significativo. Tale effetto influenza i cambiamenti di composizione del latte durante la fase produttiva della vacca, mentre l’ordine di parto non ha evidenziato alcun legame importante con i caratteri analizzati. Alcuni parametri, soprattutto quelli relativi alla texture, sembrano legati alla resa casearia del latte. La raccolta di questi caratteri, a livello individuale, permetterà anche la stima dei parametri genetici.