Dissertations / Theses on the topic 'Nature variables'
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Jones, William I. "Examining Preservice Science Teacher Understanding of Nature of Science: Discriminating Variables on the Aspects of Nature of Science." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1284776708.
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Fields, Alexander James. "Nature of anger in the workplace| Exploration of relevant variables and their structure." Thesis, The University of Texas at San Antonio, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1605134.
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In the workplace, counter productive work behaviors (CWBs) are strongly discouraged. Vardi and Weitz (2004) concluded that counter productive work behaviors are a fairly common occurrence and cost businesses billions of dollars each year. Many of these CWBs are perpetrated by angry or disgruntled employees. When angry employees are identified they can be helped with coping strategies to productively manage their anger, as opposed to engaging in CWBs (Hargrave, Hiatt, Dannenbaum, & Shaffer, 2008). This paper seeks to better equip professionals and researchers with tools to identify these at risk employees. Specifically the Anger Parameters Scales (APS) and the Anger Expressions Scale (AES) have been examined in a workplace sample for the first time. Additionally this study has examined the use of more readily available demographic information to predict at risk persons. The expected factors of the measures in question did not emerge as predicted by the AES. The factor structure of the APS was partially validated as four of the five scales loaded well enough for further analysis. None of these scales could be captured by more available demographic variables. This study also gathered normative data on anger elicitors by means of coding narratives of participants who were asked to describe a typical anger provoking situation.
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DiPietro, Domenic J. "Effects of Nature and City Sounds on Physiological and Psychological Variables in College Students." Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1597857209685718.
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Pollard, Karen R. "The nature of the low mass supergiants : RV Tauri and R Coronae Borealis variables." Thesis, University of Canterbury. Astronomy, 1994. http://hdl.handle.net/10092/7632.
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A programme of photometric and spectroscopic observations has been undertaken in order to investigate the physical and chemical characteristics of the RV Tauri and R Coronae Borealis variables. These characteristics have, in turn, been used to examine a variety of theoretical models that attempt to describe the pulsation mechanisms, the underlying physical nature and the evolutionary status of these low mass supergiant variables.
Long time baseline BVRI photometry was obtained at the Mt John University Observatory (MJUO) over intervals of between 750 and 1300 days for eleven of the RV Tauri variables. RV Tauri stars from both the RVa (constant mean magnitude) and RVb (varying mean magnitude) photometric subclasses and from all three spectroscopic Preston subtypes (A, B and C types) were included in the programme.
Fourier and least-squares analyses of the light and colour variations have revealed the dominant periodicities and the stability of the pulsation in these stars. A harmonic (f + 2f) fit was found to be a good representation of the "deep-shallow" nature of both the light and colour curves in most stars. Contemporaneous high-resolution spectroscopy of these objects was acquired at MJUO and at the Mt Stromlo Observatory. This enabled us to link the photometric variations and the radial motions in these stars' atmospheres and to relate any photometric and spectral peculiarities. The appearance and phase-dependent behaviour of the Hα line profiles and the radial velocities were examined. Shock-related features, such as line doubling and recombination emission lines, were observed in all the programme stars. The observed Hα profiles were consistent with two enhancements of Hα emission following the passage of the primary and secondary shock waves through the photosphere around phases 0.2 and 0.6. In addition, the metallic lines showed profiles characteristic of an atmospheric shock wave at these phases.
The derived spectroscopic and the photometric characteristics have been used to examine a variety of theoretical models that attempt to describe the pulsation mechanisms and the underlying physical nature of the RV Tauri stars.
The nature of the RVb subclass and the interpretation that the RVa and RVb stars actually represent a continuum of properties is discussed in detail. A model of a binary system which undergoes periodic eclipses by dust or which interacts at certain orbital phases is presented. Two scenarios were proposed to explain the observed properties: an 'obscuration' model where the star is eclipsed by dust in the binary system; or an 'interaction' scenario where the two stars interact in some manner at a particular orbital phase. The interaction model generally has better agreement with the observed properties although it is quite likely, in a system where circumstellar and/or circumbinary material is known to exist, that a combination of obscuration and interaction is possible.
A detailed analysis of the chemical composition of a number of RCB stars in the Galaxy and the Large Magellanic Cloud is presented. This study made use of high-resolution echelle spectra obtained at the Anglo-Australian Telescope. The results for the galactic star, SU Tau, revealed very similar properties to a number of other warm galactic RCB stars, most notably R CrB. This was the first abundance analysis completed for any extragalactic RCB stars and showed a similar abundance distribution to the galactic RCB stars. All these objects (galactic and extragalactic) have a reasonably consistent set of properties, providing evidence that it is possible for this phenomenon to exist in different nucleosynthetic environments.
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Bastille-Denis, Emmanuelle. "La nature et le rôle des variables psychologiques comme facteurs de maintien du trouble lié à l'horaire de travail." Doctoral thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/26289.
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Pour les travailleurs de nuit, le sommeil revêt un caractère particulier. En effet, le travail de nuit implique de modifier le cycle éveil-sommeil en fonction de l’horaire de travail, ce qui amène les travailleurs à dormir le jour alors que leur horloge biologique interne favorise plutôt l’éveil. Certains travailleurs en viennent à développer un trouble du sommeil qui s’appelle le trouble lié à l’horaire de travail (THT). Cette thèse doctorale vise à élargir la conceptualisation actuelle dominante de ce trouble, en étudiant les cognitions, les comportements incompatibles avec le sommeil et les processus anxieux comme facteurs de maintien du THT. Le premier objectif vise à étudier la nature des cognitions avant l’endormissement dans le THT. Le deuxième objectif est d’étudier la présence de cognitions dysfonctionnelles et de comportements incompatibles avec le sommeil dans le THT. Un dernier objectif vise à explorer le thème des inquiétudes concernant le sommeil et la présence du processus de catastrophisation avant l’endormissement dans le THT. Quarante-sept travailleurs de nuit ont participé à l’étude. Les participants ont été divisés en deux groupes : 25 personnes présentant un THT et 22 personnes étant de bons dormeurs (BD) satisfaits de leur sommeil. L’étude comporte des mesures autorapportées ainsi que des entrevues en face-à-face ciblant les différents thèmes de pensées avant l’endormissement, les pensées et croyances dysfonctionnelles, les pensées intrusives, les stratégies de contrôle des pensées, les biais attentionnels, les inquiétudes portant sur le sommeil ainsi que les comportements incompatibles avec le sommeil. Les résultats du premier article démontrent que le groupe THT porte significativement plus son attention sur les soucis et les préoccupations ainsi que sur les bruits à l’intérieur ou à l’extérieur de la maison que les BD. Les personnes souffrant de THT ont davantage d’activation cognitive avant l’endormissement et ont une efficacité du sommeil plus faible comparées aux BD. Les résultats du deuxième article révèlent que 77 % des participants ont pris part au processus de catastrophisation. Parmi les thèmes mentionnés se trouvent la fatigue et le niveau d’énergie, les difficultés reliées à l’humeur et la performance au travail. Ces résultats suggèrent que des cognitions et comportements contribuent au maintien du THT. Des études futures devraient viser à approfondir les facteurs psychologiques impliqués dans ce trouble.
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Przyjemski, Katrina. "Natural language variables : variable-based semantic theories of pronouns and proper names." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:2ec9cd7c-5fe3-4dd5-ae3b-e94e317246c1.
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Semanticists, philosophers and logicians have standardly analyzed a range of natural language expressions on the model of the variables of formal languages. This dissertation explores variable- based semantic theories of pronounsand proper names. The first two chapters argue that a variable-based, presuppositional semantics for pronouns proposed by Cooper (1979, 1983) resolves an apparent trilemma arising from the conjunction of three plausible commitments concerning the semantics of pronouns: that some anaphoric pronouns with quantifier antecedents are bound variables, that referential pronouns have context-independent meanings, and that the relation between bound and referential pronouns is not ambiguity or homonymy. The first chapter argues that Cooper’s semantics is descriptively and empirically superior to alternative theories, including Kaplan’s account, which does not resolve the trilemma. The second addresses an important objection to the view that bound and referential pronouns make the same semantic contribution, involving cases where bound pronouns do not appear to trigger semantic presuppositions. I argue that this appearance is misleading: bound pronouns do trigger semantic presuppositions and have the same (Cooper-style) denotations as referential pronouns. The third chapter addresses the phenomenon of non c-command or ‘donkey’ anaphora. These anaphors appear to require a departure from Cooper’s semantics and, more generally, from the view that anaphoric pronouns correspond to (classical) bound variables. I consider D-type accounts of donkey anaphora and argue that these accounts must be revised in ways that bring the denotations of donkey anaphors closer to those of ordinary bound and referential pronouns. The last chapter asks whether proper names require a variable-based semantics. I consider a pair of recent anaphoric theories of proper names, according to which proper names have anaphoric uses and are thus better modeled as variables. I argue that there are important reasons to reject a variable-based model for proper names, in contrast with pronouns.
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Sarrazin, Philippe. "Motivation a l'accomplissement dans les activites motrices : mise en evidence de processus et variables affectant les croyances relatives a la nature de l'habilete motrice, le choix d'une difficulte, l'effort fourni et la performance." Paris 11, 1995. http://www.theses.fr/1995PA112394.
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Ce travail a pour objectif de mettre en evidence certaines variables et processus qui affectent la motivation a l'accomplissement, dans les activites motrices. Il s'appuie sur des donnees issues du paradigme expectation-valence (vroom, 1964), et des theories socio-cognitives contemporaines sur les buts (nicholls, 1989). La premiere partie presente les concepts et theories de la motivation en generale, et de la motivation a l'accomplissement en particulier. Les notions d'expectation, de valence et de motivation a l'accomplissement y sont particulierement developpees. La deuxieme est un approfondissement theorique des deux variables independantes principales (l'orientation motivationnelle vers la maitrise et vers la competition, et l'habilete percue en escalade), assorti de la validation d'outils destines a les mesurer. La troisieme partie propose 1 etude et 7 experimentations regroupees selon 4 themes: les croyances relatives a la nature de l'habilete motrice, le choix d'un niveau de difficulte de la tache, l'effort et la perseverance dans la tache, et la performance. Dans ce qu'ils ont d'essentiel, nos resultats montrent qu'avec un but de competition, la motivation est tributaire d'une perception favorable de son habilete par rapport a autrui. Ce processus peut entrainer des pis-aller quand l'habilete percue est faible: la selection de difficultes extremes, l'adoption de strategies de moindre effort ou le rejet de la situation. Par contraste, quelle que soit l'habilete percue, un but de maitrise entraine la selection d'une tache de defi personnel, et un investissement important et durable, particulierement pour ce type de difficulte. La consistance des resultats valide dans un contexte ecologique et avec une tache motrice d'escalade les hypotheses avancees par certaines theories socio-cognitives contemporaines, celles de nicholls (1989) en particulier, et consacre la valeur du paradigme expectation-valence pour expliquer le fonctionnement de la motivation humaine
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Stump, Simon. "Natural enemies in a variable world." Thesis, The University of Arizona, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3718576.
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Natural enemies are ubiquitous in nature. In many communities, natural enemies have a major effect on the diversity of their prey. Their effects are very diverse: they can promote or undermine the ability of their prey to coexist through a variety of mechanisms. As such, an important step in understanding how diversity is maintained will be to understand how different forms of predator behavior affect prey coexistence. In this dissertation, I study how two major types of predators affect plant coexistence in two different communities.
First, I study natural enemies in tropical forests, using both theory and empirical work. In tropical forests, most natural enemies are thought have a narrow host range, and be distance-responsive (i.e., mainly harm seeds and seedlings that are near adults of their main host). Previous theoretical work has shown that specialized natural enemies can maintain diversity of their prey, whether or not they are distance-responsive. However, it is unknown whether specialist natural enemies are more or less able to promote prey coexistence if they are distance-responsive. Using theoretical models, I show that distance-responsive predators are less able to maintain diversity. Additionally, I show that habitat partitioning does not interfere with the ability of distance-responsive predators to maintain diversity, even if it causes seedling survival to be highest near conspecific adults.
From an empirical aspect, I studied the host range of seed-associated fungi. Soil-borne microbes, such as fungi, are thought to play an important role in maintaining diversity in tropical forests. However, the microbial community itself is often treated as a black box, and little is known about which microbes are causing major effects, or how specialized seed-microbe associations are. Here I use experimental inoculations to examine the host range and effect of a guild of seed-associated fungi that are thought to be mainly pathogens. I show that fungal species are differentially able to colonize different seed species, and have species-specific effects on seed germination. I show that in many cases, plant phylogeny, and to a lesser extent fungus phylogeny, are good predictors of colonization.
Finally, I study how an optimally foraging granivore can promote (or undermine) coexistence amongst annual plants, using theory. Optimal foraging theory is one of the major theories for how predators behave; despite this, little is known about whether an optimally foraging predator could promote coexistence amongst a diverse community of prey. Previous models have shown than two species can coexist due to optimal foraging, but did not test whether multiple prey can coexist, nor if the effect is altered by environmental variation. Here, I show that if the predators specialize on different prey at different times, the predators can allow multiple prey species to coexist. In this case, environmental variation has little effect on the ability of predators to maintain diversity. If the predators are generalists, they cannot maintain diversity. Additionally, I show that generalist predators will create a negative storage effect, undermining coexistence.
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Stump, Simon Maccracken. "Natural Enemies in a Variable World." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/560856.
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Natural enemies are ubiquitous in nature. In many communities, natural enemies have a major effect on the diversity of their prey. Their effects are very diverse: they can promote or undermine the ability of their prey to coexist through a variety of mechanisms. As such, an important step in understanding how diversity is maintained will be to understand how different forms of predator behavior affect prey coexistence. In this dissertation, I study how two major types of predators affect plant coexistence in two different communities. First, I study natural enemies in tropical forests, using both theory and empirical work. In tropical forests, most natural enemies are thought have a narrow host range, and be distance-responsive (i.e., mainly harm seeds and seedlings that are near adults of their main host). Previous theoretical work has shown that specialized natural enemies can maintain diversity of their prey, whether or not they are distance-responsive. However, it is unknown whether specialist natural enemies are more or less able to promote prey coexistence if they are distance-responsive. Using theoretical models, I show that distance-responsive predators are less able to maintain diversity. Additionally, I show that habitat partitioning does not interfere with the ability of distance-responsive predators to maintain diversity, even if it causes seedling survival to be highest near conspecific adults. From an empirical aspect, I studied the host range of seed-associated fungi. Soilborne microbes, such as fungi, are thought to play an important role in maintaining diversity in tropical forests. However, the microbial community itself is often treated as a black box, and little is known about which microbes are causing major effects, or how 8 specialized seed-microbe associations are. Here I use experimental inoculations to examine the host range and effect of a guild of seed-associated fungi that are thought to be mainly pathogens. I show that fungal species are differentially able to colonize different seed species, and have species-specific effects on seed germination. I show that in many cases, plant phylogeny, and to a lesser extent fungus phylogeny, are good predictors of colonization. Finally, I study how an optimally foraging granivore can promote (or undermine) coexistence amongst annual plants, using theory. Optimal foraging theory is one of the major theories for how predators behave; despite this, little is known about whether an optimally foraging predator could promote coexistence amongst a diverse community of prey. Previous models have shown than two species can coexist due to optimal foraging, but did not test whether multiple prey can coexist, nor if the effect is altered by environmental variation. Here, I show that if the predators specialize on different prey at different times, the predators can allow multiple prey species to coexist. In this case, environmental variation has little effect on the ability of predators to maintain diversity. If the predators are generalists, they cannot maintain diversity. Additionally, I show that generalist predators will create a negative storage effect, undermining coexistence.
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Bogaerts, Márquez María 1991. "Identification of environmental variables in Drosophila melanogaster natural populations." Doctoral thesis, TDX (Tesis Doctorals en Xarxa), 2022. http://hdl.handle.net/10803/673159.
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Entender cómo las especies se adaptan al ambiente es aún una pregunta sin resolver
en el campo de la Biología Evolutiva. Mientras el foco principal siempre ha estado en
la base genética, los factores ambientales responsables de dichos procesos
adaptativos se quedan por detrás. Nuestro objetivo principal es identificar las
principales variables ambientales que contribuyen a la adaptación. Utilizamos
poblaciones naturales de D. melanogaster de Europa y Norte América, y analizamos
tanto SNPs como elementos transponibles (TEs). Para detectar y estimar las
frecuencias de una población con precisión, actualizamos el algoritmo de T-lex y
lanzamos una nueva versión: T-lex3. Realizamos un análisis de Asociación GenomaAmbiente (GEA) para awsociar las frecuencias alélicas de TEs y SNPs con las
diferentes variables ambientales, e identificamos temperatura, lluvia y viento, como
las variables más relevantes implicadas en la adaptación ambiental. Tambien
encontramos 10 TEs asociados con al menos, una variable ambiental. Finalmente,
desarrollamos una herramienta bioinfórmatica para integrar más de 200 genomas de
D. melanogaster de todo el mundo, lo que facilitará los análisis ambientales espacial
y temporalmente.Understanding how species adapt to the environment is still an open question in Evolutionary Biology. While the focus has been on the genetic basis, the analysis of the environmental factors which drive these adaptive processes lags behind. Our main goal is to identify the main environmental variables that contribute to adaptation. We used natural D. melanogaster populations from Europe and North America, and analyzed both SNPs and transposable elements (TEs). To accurately detect and estimate TE population frequencies, we updated the T-lex algorithm and released a new version: T-lex3. We performed a Genome-Environment Analysis (GEA) to associate TEs and SNP allele frequencies with several environmental variables, and we identified temperature, rainfall and wind as the relevant variables involved in environmental adaptation. In addition, we found 10 TEs associated with an environmental variable. Finally, we developed a bioinformatic pipeline that integrates >200 D. melanogaster world-wide genomes, which will facilitate environmental analysis in space and time.
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Gayral, Françoise. "Sémantique du langage naturel et profondeur variable : Une première approche." Paris 13, 1992. http://www.theses.fr/1992PA132004.
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Le travail que nous présentons concerne la sémantique du langage naturel. Il se situe dans le cadre de ce que la tradition informatique appelle compréhension du langage naturel. Apres avoir tenté de cerner les enjeux de cette discipline et avoir analysé les différents courants existants, nous présentons un système: le système à profondeur variable. Celui-ci s'appuie sur un appareil logique, précisément une logique non monotone. Les nombreuses connaissances exigées dans le processus de compréhension d'un texte sont représentées dans le système grâce à un ensemble de concepts et de règles. Nous montrons sur trois applications en quoi ce système apporte des éléments de réponse intéressants à certains problèmes sémantiques. Une application concerne l'élaboration d'une ontologie temporelle pour un traitement sémantique de récits en langage naturel. Cette ontologie rend compte des phénomènes temporels de la langue et concrétise cette capacité de la langue à multiplier les points de vue sur une entité temporelle. Une autre tente, sur un court texte, un travail sémantique complet prenant en compte de manière homogène les différents types de connaissances, du lexique aux connaissances du monde. Enfin, nous traitons d'un corpus composé de textes de constats d'accident de voiture. Nous cherchons à reproduire un raisonnement physique de sens commun qui semble souvent loin d'un raisonnement de physique traditionnelle et nous formalisons, pour cela, des éléments d'une physique naïve adaptée à ces textes.
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Yi, Jon Rong-Wei 1975. "Natural-sounding speech synthesis using variable-length units." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50438.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (p. 112-115).
by Jon Rong-Wei Yi.
M.Eng.
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Balendra, Padma Rani. "Deep vein thrombosis of the leg : natural history and haemostatic variables." Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334477.
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Ishizaki, Masato. "Mixed-initiative natural language dialogue with variable communicative modes." Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/518.
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As speech and natural language processing technology advance, it now reaches a stage where the dialogue control or initiative can be studied to realise usable and friendly human computer interface programs such as computer dialogue systems. One of the major problems concerning dialogue initiative is who should take the dialogue initiative when. This thesis tackles this dialogue initiative problem using the following approaches: 1. Human dialogue data is examined for their local dialogue structures; 2. A dialogue manager is proposed and implemented, which handles variations of human dialogue data concerning the dialogue initiative, and experimental results are obtained by having the implemented dialogue managers working with a parser and a generator exchange natural language messages with each other; and 3. A mathematical model is constructed and used to analyse who should take the dialogue initiative when. The first study shows that human dialogue data varies concerning the number of utterance units in a turn and utterance types independently of the difference of the dialogue initiative. The second study shows that the dialogues in which the dialogue initiative constantly alters (mixed-initiative dialogues) are not always more efficient than those in which the dialogue initiative does not change (non mixed-initiative dialogues). The third study concludes that under the assumption that both speakers solve a problem under similar situations, mixed-initiative dialogues are more efficient than non-mixed-initiative dialogues when initiating utterances can reduce a problem search space more efficiently than responding utterances. The above conclusion can be simplified to the condition that the agent should take the dialogue initiative when s/he can make an effective utterance like in the situations where s/he has more knowledge than the partner with respect to the current goal.
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McCartney, Ellen J. "Effect of contextual variables on mealtime problem behavior in the natural environment." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3593.
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Thesis (M.A.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains v, 50 p. : ill. Includes abstract. Includes bibliographical references (p. 30-35).
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Lane, Peter. "Simple synchrony networks : a new connectionist architecture applied to natural language parsing." Thesis, University of Exeter, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322386.
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Das, Dipanjan. "Semi-Supervised and Latent-Variable Models of Natural Language Semantics." Research Showcase @ CMU, 2012. http://repository.cmu.edu/dissertations/342.
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This thesis focuses on robust analysis of natural language semantics. A primary bottleneck for semantic processing of text lies in the scarcity of high-quality and large amounts of annotated data that provide complete information about the semantic structure of natural language expressions. In this dissertation, we study statistical models tailored to solve problems in computational semantics, with a focus on modeling structure that is not visible in annotated text data. We first investigate supervised methods for modeling two kinds of semantic phenomena in language. First, we focus on the problem of paraphrase identification, which attempts to recognize whether two sentences convey the same meaning. Second, we concentrate on shallow semantic parsing, adopting the theory of frame semantics (Fillmore, 1982). Frame semantics offers deep linguistic analysis that exploits the use of lexical semantic properties and relationships among semantic frames and roles. Unfortunately, the datasets used to train our paraphrase and frame-semantic parsing models are too small to lead to robust performance. Therefore, a common trait in our methods is the hypothesis of hidden structure in the data. To this end, we employ conditional log-linear models over structures, that are firstly capable of incorporating a wide variety of features gathered from the data as well as various lexica, and secondly use latent variables to model missing information in annotated data. Our approaches towards solving these two problems achieve state-of-the-art accuracy on standard corpora. For the frame-semantic parsing problem, we present fast inference techniques for jointly modeling the semantic roles of a given predicate. We experiment with linear program formulations, and use a commercial solver as well as an exact dual decomposition technique that breaks the role labeling problem into several overlapping components. Continuing with the theme of hypothesizing hidden structure in data for modeling natural language semantics, we present methods to leverage large volumes of unlabeled data to improve upon the shallow semantic parsing task. We work within the framework of graph-based semi-supervised learning, a powerful method that associates similar natural language types, and helps propagate supervised annotations to unlabeled data. We use this framework to improve frame-semantic parsing performance on unknown predicates that are absent in annotated data. We also present a family of novel objective functions for graph-based learning that result in sparse probability measures over graph vertices, a desirable property for natural language types. Not only are these objectives easier to numerically optimize, but also they result in smoothed distributions over predicates that are smaller in size. The experiments presented in this dissertation empirically demonstrates that missing information in text corpora contain considerable semantic information that can be incorporated into structured models for semantics, to significant benefit over the current state of the art. The methods in this thesis were originally presented by Das and Smith (2009, 2011, 2012), and Das et al. (2010, 2012). The thesis gives a more thorough exposition, relating and comparing the methods, and also presents several extensions of the aforementioned papers.
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Price, Zahrah. "An investigation of socioeconomic status (SES) as a variable affecting the nature of mother-infant interaction." Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/2933.
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Azzabou, Noura. "Variable Bandwidth Image Models for Texture-Preserving Enhancement of Natural Images." Paris Est, 2008. http://pastel.paristech.org/4041/01/ThesisNouraAzzabou.pdf.
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Cette thèse s’intéresse aux problèmes de restauration d’images et de préservation de textures. Cette tâche nécessite un modèle image qui permet de caractériser le signal qu’on doit obtenir. Un tel model s’appuie sur la définition de l’interaction entre les pixels et qui est caractérisé par deux aspects : (1) la similarité photométrique entre les pixels (2) la distance spatiale entre les pixels qui peut être comparée à une grandeur d’échelle. La première partie de la thèse introduit un nouveau modèle non paramétrique d’image. Ce modèle permet d’obtenir une description adaptative de l’image en utilisant des noyaux de taille variable obtenue à partir d’une étape de classification effectuée au préalable. La deuxième partie introduit une autre approche pour décrire la dépendance entre pixels d’un point de vue géométrique. Ceci est effectué à l’aide d’un modèle statistique de la co-occurrence entre les observations de point de vue géométrique. La dernière partie est une nouvelle technique de sélection automatique (pour chaque pixel) de la taille des noyaux utilisé au cours du filtrage. Cette thèse est conclue avec l’application de cette dernière approche dans différents contextes de filtrage ce qui montre sa flexibilité vis-à-vis des contraintes liées aux divers problèmes traitésThis thesis is devoted to image enhancement and texture preservation issues. This task involves an image model that describes the characteristics of the recovered signal. Such a model is based on the definition of the pixels interaction that is often characterized by two aspects (i) the photometric similarity between pixels (ii) the spatial distance between them that can be compared to a given scale. The first part of the thesis, introduces novel non-parametric image models towards more appropriate and adaptive image description using variable bandwidth approximations driven from a soft classification in the image. The second part introduces alternative means to model observations dependencies from geometric point of view. This is done through statistical modeling of co-occurrence between observations and the use of multiple hypotheses testing and particle filters. The last part is devoted to novel adaptive means for spatial bandwidth selection and more efficient tools to capture photometric relationships between observations. The thesis concludes with providing other application fields of the last technique towards proving its flexibility toward various problem requirements
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Villarreal, Guerrero Federico. "Enhanced Greenhouse Cooling Strategy with Natural Ventilation and Variable Fogging Rates." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202717.
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High-pressure fog (HPF) systems have advantages for greenhouse cooling compared to traditional systems, such as pad and fan. Such advantages include the potential of improving climate uniformity. Water is distributed throughout the greenhouse space thus reducing water use and energy operation costs, especially if used within naturally ventilated greenhouses. Fog cooling in combination with natural ventilation is difficult to manage, primarily because accurate estimation of air exchange rates is required to determine the precise amount of fog required. This limitation on automated control has been the main reason restricting the widespread commercial use of HPF systems. The goal of this research was to develop and implement a control strategy for a naturally ventilated greenhouse with a variable HPF system. The strategy that was developed included variable rate of fog introduced into the greenhouse, a dynamic control of the air ventilation openings, and it considered the contribution of cooling and humidification from the crop by evapotranspiration. Three evapotranspiration models, including Penman-Monteith, Stanghellini and Takakura, were calibrated and evaluated in terms of prediction accuracy. The Stanghellini model provided the best overall performance for several growing seasons and under two different evaporative cooling systems (i.e. pad and fan and natural ventilation with HPF), and was selected and implemented in the cooling control strategy. The strategy utilized enthalpy and vapor pressure deficit (VPD) of the greenhouse atmosphere for the control parameters. Using a calibrated greenhouse mechanistic climate model, a computer algorithm was created to simulate the capabilities of the proposed. The control strategy that was developed was able to maintain the greenhouse climate closer to the pre-established set points while consuming less water and energy, compared to a constant HPF system based on VPD control. Finally, the strategy was implemented in a single span research greenhouse. A four-day validation study provided good agreement for measured and simulated greenhouse climate values, as well as for water and energy use. Moreover, the strategy was able to maintain VPD around its set point for all the experiments and temperature remained around its set point when outside enthalpy was lower than the enthalpy set point.
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Kaneryd, Linda. "Dynamics of ecological communities in variable environments : local and spatial processes." Doctoral thesis, Linköpings universitet, Teoretisk Biologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-76165.
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The ecosystems of the world are currently facing a variety of anthropogenic perturbations, such as climate change, fragmentation and destruction of habitat, overexploitation of natural resources and invasions of alien species. How the ecosystems will be affected is not only dependent on the direct effects of the perturbations on individual species but also on the trophic structure and interaction patterns of the ecological community. Of particular current concern is the response of ecological communities to climate change. Increased global temperature is expected to cause an increased intensity and frequency of weather extremes. A more unpredictable and more variable environment will have important consequences not only for individual species but also for the dynamics of the entire community. If we are to fully understand the joint effects of a changing climate and habitat fragmentation, there is also a need to understand the spatial aspects of community dynamics. In the present work we use dynamic models to theoretically explore the importance of local (Paper I and II) and spatial processes (Paper III-V) for the response of multi-trophic communities to different kinds of perturbations. In paper I we investigate how species richness and correlation in species responses to a highly variable environment affect the risk of extinction cascades. We find that the risk of extinction cascades increases with increasing species richness especially when the correlation among species is low. Initial stochastic extinctions of primary producer species unleash bottomup extinction cascades, where specialist consumers are especially vulnerable. Although the risks of extinction cascades were higher in the species-rich systems, we found that the temporal stability of aggregate abundance of primary producers increased with increasing richness. Thus, species richness had a two-sided effect on community stability. Also during the extinction cascades it is possible that more robust species and interaction patterns will be selected which would further act to stabilize the post-extinction communities. In paper II we explore how the process of disassembly affects the structure of the interaction network and the robustness of the community to additional disturbances. We find that the disassembled communities are structurally different and more resistant to disturbances than equally sized communities that have not gone through a phase of disassembly. The disassembled communities are topologically as well as dynamically more stable than non-disassembled communities. In paper III, IV and V we expand the analysis to incorporate the spatial dimension. In paper III we analyze how metacommunities (a set of local communities coupled by species dispersal) in spatially explicit landscapes respond to environmental variation. We examine how this response is affected by varying 1) species richness in the local communities, 2) the degree of correlation in species response to the environmental variation, between species within patches (species correlation) and among patches (spatial correlation) and 3) dispersal pattern of species. First we can confirm that our previous findings from paper I regarding local species richness and correlation among species within a patch are robust to the inclusion of a spatial dimension. However our results also show that the spatial dynamics are of great importance: first we find that the risk of global extinctions increases with increasing spatial correlation. Second we find that the pattern and rate of dispersal are important; a high migration rate in combination with localized dispersal decrease the risk of global extinctions whereas a global dispersal pattern increases the risk of global extinctions. When dispersal is global the subpopulations of a species become more synchronized which reduces the potential for a patch to become recolonized following extinctions. We also demonstrate the importance of both local and spatial processes when examining the temporal stability of primary production at the scale of metapopulations, local communities and metacommunities. In paper IV we investigate how the spatial structure of the landscape (number of patches) and dispersal pattern of species affect a metacommunities response to increased mortality during dispersal and local loss of species. We find a two-sided effect of dispersal on metacommunity persistence; on the one hand, high migration rate significantly reduces the risk of bottom-up extinction cascades following the removal of a species when dispersal involves no risk. On the other hand, high migration rate increases extinction risks when dispersal imposes a risk to the dispersing individuals, especially when dispersal is global. Species with long generation times at the highest trophic level are particularly vulnerable to extinction when dispersal involves a risk. These results suggest that decreasing the mortality risk of dispersing individuals by constructing habitat corridors or by improving the quality of the habitat matrix might greatly increase the robustness of metacommunities to local loss of species by enhancing recolonisations and rescue effects. In paper V we use network theory to identify keystone patches in the landscape, patches that are of critical importance for the local and global persistence of species in the metacommunity. By deleting patches one at a time and investigating the risk of local and global extinctions we quantified the importance of a patch’s position in the landscape for the persistence of species within the metacommunity. A selection of indices were used including some local indices that measure the connectedness of a patch in the intact network and some indices which measure the decrease in a global index after the deletion of the patch from the network. Global indices are those that give an impression of the connectivity of the entire patch network. We find that deletion of patches contributing strongly to the connectivity of the entire patch network had the most negative effect on species persistence.
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Lögdberg, Frida. "Population dynamics in variable environments – impacts of noise colour and synchrony." Doctoral thesis, Linköpings universitet, Teoretisk Biologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-72951.
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Environmental variation is an essential part of population dynamics, and two characteristics of such variation—variance and the temporal autocorrelation termed ‘noise colour’—are essential for determining the persistence of a population. In addition, the spatial correlation of local environmental variation between habitat patches (i.e., synchrony) is equally important in subdivided populations connected via dispersal. The research underlying this thesis explored the effects of noise colour and synchrony on population dynamics. The dynamics were studied primarily in single-species models with fast or slow population responses to environmental changes, and several-species systems (i.e., food webs) with different stability properties were also considered. Populations were spatially subdivided with local dynamics in discrete patches, and patch positions were modelled either implicitly or explicitly, with different landscape configurations in the latter case. It has previously been shown that the effect of increased environmental redness on extinction risk in nonspatial models depends on population responsiveness, seen as increased and decreased risks for fast and slow responding populations, respectively. Here, increased redness of noise decreased the extinction risk for fast-responding populations (in accordance with non-spatial studies) in a simple implicit landscape model (Papers I and II). Slow-responding populations in some cases showed a raised extinction risk for intermediate noise colour values (Paper I), which does not agree with earlier results. However, increasing the spatial complexity evened out the differences that were caused by responsiveness (Papers III and IV). Thus, in general, the explicit landscape models displayed a decrease in extinction risk with increasing environmental redness regardless of whether the populations were fast or slow in responding to environmental variation. Still, fast and slow responsiveness of populations differed in relation to the following: overall levels of extinction risk (Papers I, III, and IV), synchrony of population variations (Paper II), colour of population variations (Paper II), and response to landscape structure (Papers III and IV). For fast-responding populations, the degree of synchrony of population variations was similar to the synchrony of environmental noise (Paper II). Local populations of a model organism that responded slowly to environmental variation were more synchronized than the environmental variation itself, and the largest shift between the environment and the populations was seen for intermediate red noise colours (Paper II). This indicated that dispersal-induced population synchrony could be enhanced by reddened noise. Landscape configuration proved to be important for the general levels of extinction risk. This effect was most pronounced for fast-responding populations (Papers III and IV) and became even more distinct when distance-dependent synchrony was added between the environmental variations (Paper IV). Adding explicit landscapes led to an decrease in the differences between fast- and slow-responding populations, when considering the influence of noise colour on extinction risk. Also, landscape configuration affected the importance of degree of synchrony through its impact on distances between patches, which resulted in configurations where extinction risk depended solely on noise colour. The effects on stability exerted by populations embedded in food webs were investigated in an implicit landscape model (Paper V). Three types of food webs with different properties of inherent stability all showed a decrease in stability at increased environmental variance and increased redness of environmental variation. In conclusion, the single-species models showed that the survival conditions of populations that were near extinction were improved by all of the following: decreased synchrony, reddening of noise, and aggregation of patches. The results of the web simulations indicate that we need better understanding of how findings obtained using single-species models can be used to reveal the effects of noise colour on species communities. From a management perspective, altering landscape structure may compensate for increased extinction risks caused by changed noise colour of environmental variation, which is a predicted outcome of climate change.
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Binot, Aurélie. "La conservation de la nature en Afrique centrale entre théorie et pratiques. Des espaces protégés à géométrie variable." Phd thesis, Université Panthéon-Sorbonne - Paris I, 2010. http://tel.archives-ouvertes.fr/tel-00508990.
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Cette thèse propose une analyse des projets intégrant conservation de la faune sauvage et développement en Afrique centrale, dans la mouvance des approches participatives qui se sont développées à partir des années 1980 au sein de projets de coopération multilatérale. Nous mettons en évidence la représentation des espaces à enjeux de conservation qui domine très nettement le paysage de la conservation intégrée. Cette représentation est produite sur la base d'une opposition de type centre/périphérie entre les espaces naturels à conserver et les aires de production attenantes. Elle génère des modèles de développement et de gouvernance locaux stéréotypés, ainsi que des approches de zonage en profond décalage avec les pratiques locales, notamment en termes de gestion foncière. C'est également cette représentation territoriale centripète qui est à l'origine de rapports de force et de conflits récurrents dans la gestion des aires protégées. Ces jeux de pouvoir s'érigent en obstacle à la participation active des communautés locales aux actions de conservation. Nous illustrons notre propos à partir d'une lecture critique de la rhétorique qui s'est construite autour des paradigmes du Développement Durable appliqués à la conservation de la biodiversité et sur la base de l'expérience de plusieurs projets de terrain mis en œuvre en Afrique centrale. Nous nous appuyons particulièrement sur l'étude de cas du parc national de Zakouma (Tchad) et sur son dispositif d'aménagement du territoire, caractéristique des pratiques conservationnistes en Afrique centrale.
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Binot, Aurélie. "La conservation de la nature en Afrique centrale entre théories et pratiques : des espaces protégés à géométrie variable." Paris 1, 2010. https://tel.archives-ouvertes.fr/tel-00508990.
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Cette thèse propose une analyse des projets intégrant conservation de la faune sauvage et développement en Afrique centrale, dans la mouvance des approches participatives qui se sont développées à partir des années 1980 au sein de projets de coopération multilatérale. Une représentation des espaces à enjeux de conservation, produite sur la base d'une opposition de type centre/périphérie entre les espaces naturels à conserver et les aires de production attenantes, domine très nettement Ie paysage de la conservation intégrée. Cette représentation centripète génère des modèles et de gouvernance locale stéréotypés, ainsi que des approches de zonage en profond décalage avec les pratiques locales, notamment en termes de gestion foncière. Elle est également à I' origine de rapports de force et de conflits récurrents dans la gestion des aires protégées, qui s'érigent en obstacle à la participation active des communautés locales aux actions de conservation. Nous nous appuyons notamment sur I' étude de cas du parc national de Zakouma (Tchad), dont le dispositif d'aménagement du territoire est caractéristique des pratiques conservationnistes en Afrique centrale.
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Liu, Jingshu. "Unsupervised cross-lingual representation modeling for variable length phrases." Thesis, Nantes, 2020. http://www.theses.fr/2020NANT4009.
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L’étude de l’extraction de lexiques bilingues à partir de corpus comparables a été souvent circonscrite aux mots simples. Les méthodes classiques ne peuvent gérer les expressions complexes que si elles sont de longueur identique, tandis que les méthodes de plongements de mots modélisent les expressions comme une seule unité. Ces dernières nécessitent beaucoup de données, et ne peuvent pas gérer les expressions hors vocabulaire. Dans cette thèse, nous nous intéressons à la modélisation d’expressions de longueur variable par co-occurrences et par les méthodes neuronales état de l’art. Nous étudions aussi l’apprentissage de représentation d’expressions supervisé et non-supervisé. Nous proposons deux contributions majeures. Premièrement, une nouvelle architecture appelée tree-free recursive neural network (TFRNN) pour la modélisation d’expressions indépendamment de leur longueur. En apprenant à prédire le contexte de l’expression à partir de son vecteur encodé, nous surpassons les systèmes état de l’art de synonymie monolingue en utilisant seulement le texte brut pour l’entraînement. Deuxièmement, pour la modélisation cross-lingue, nous incorporons une architecture dérivée de TF-RNN dans un modèle encodeur-décodeur avec un mécanisme de pseudo contre-traduction inspiré de travaux sur la traduction automatique neurale nonsupervisée. Notre système améliore significativement l’alignement bilingue des expressions de longueurs différentesSignificant advances have been achieved in bilingual word-level alignment from comparable corpora, yet the challenge remains for phrase-level alignment. Traditional methods to phrase alignment can only handle phrase of equal length, while word embedding based approaches learn phrase embeddings as individual vocabulary entries suffer from the data sparsity and cannot handle out of vocabulary phrases. Since bilingual alignment is a vector comparison task, phrase representation plays a key role. In this thesis, we study the approaches for unified phrase modeling and cross-lingual phrase alignment, ranging from co-occurrence models to most recent neural state-of-the-art approaches. We review supervised and unsupervised frameworks for modeling cross-lingual phrase representations. Two contributions are proposed in this work. First, a new architecture called tree-free recursive neural network (TF-RNN) for modeling phrases of variable length which, combined with a wrapped context prediction training objective, outperforms the state-of-the-art approaches on monolingual phrase synonymy task with only plain text training data. Second, for cross-lingual modeling, we propose to incorporate an architecture derived from TF-RNN in an encoder-decoder model with a pseudo back translation mechanism inspired by unsupervised neural machine translation. Our proposition improves significantly bilingual alignment of different length phrases
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Pérez, Sáez Juan G. "Recruiting the Water Quality Trader: Do Socioeconomic Variables and Levels of Trust Matter?" The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397745413.
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Wadie, Iain Hugh Charles. "Modelling of natural flexible variable structures for the automatic processing of meat carcasses." Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336942.
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Richwine, Pebble Lea. "The Impact of Authentic Science Inquiry Experiences Studying Variable Stars on High School Students' Knowledge and Attitudes about Science and Astronomy and Beliefs Regarding the Nature of Science." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/194456.
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The purpose of this concurrent mixed methods study was to investigate the impact on high school students' knowledge and attitudes regarding astronomy and beliefs about the nature of science after participating in an extended authentic, inquiry-oriented, research experience studying variable stars using a specifically designed curriculum guide "In the Hunt for Variable Stars." The study gathered quantitative data using a pretest posttest strategy on a modified form of an existing questionnaire called Students Attitudes Toward Astronomy and four student-supplied response content surveys. Qualitative methods included analysis of researcher's field notes, naturalistic observations, formal interviews, and students' artifacts. The methods and results of this study provided important baseline information to measure cognitive and affective changes resulting from an authentic scientific research experience for high school students.Ninety students participated in a targeted instructional sequence and their attitudes and knowledge were compared to 50 students in a comparable science course who were not provided an authentic research experience. The results obtained in this study strongly suggest that participation in research is successful at significantly increasing content knowledge. All four content surveys showed statistically significant increases for students in the intervention group as compared to the students in the non-intervention group. Qualitative results demonstrated that both groups of students initially held naïve ideas about science and astronomy. After participation in the intervention, the most dramatic changes were observed in students' understanding of astronomy content. No substantial change was seen in students' attitudes toward Astronomy and science but there is evidence of some limited impacts on beliefs regarding the nature of science.In combination, the data resulting from this mixed-method study lend considerable weight to claim in contemporary science education reform that students will learn and more scientifically accurate knowledge of astronomy after participating in authentic inquiry experiences.
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liu, xian. "PREDICTION OF NON-NATIVE INVASIVE PLANT SPECIES OCCURRENCES IN RELATION TO ENVIRONMENTAL VARIABLES IN SOUTHERN ILLINOIS." OpenSIUC, 2021. https://opensiuc.lib.siu.edu/dissertations/1911.
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Non-native invasive plants are destructive plants brought into places where they did occur before naturally. The rapid spread of non-native invasive plants has become an urgent threat to ecosystems at a global scale, and it is a top priority problem for natural resources management. The overall objective of this project is to predict the occurrence of some common non-native invasive plants species in Southern Illinois to allow management policies to be developed.Seventeen of the most common and abundant non-native invasive species in Southern Illinois were analyzed. Eleven environmental variables were used to model species distributions and estimate their importance to species distributions. Results showed that land cover and soil (major land resource area) were the two most significant variables related to most of focal species distributions and made the most contributions in this study. Prediction maps indicated that most species had high probabilities of occurrence at the central south and along the riversides of the Southern Illinois area. To explore how climate change affects species invasions and habitats, an ensemble of 5 commonly used atmosphere-ocean general circulation models (AOGCMs) (CanESM2, CCSM 4.0, CGCM3.0, CSIRO MK3.5, and NorESM) were used to project future climate conditions. Overall, land cover and soil types (major land resource area) were the two most significant non-climate variables related to most of focal species distributions. Species with a narrow habitat or which preferred specific habitats would be mostly affected by land cover types and soil types while species (e.g., Lonicera maackii) having wide habitat tolerance would be least impacted. Prediction maps showed that most species had distribution trends from east to west in the central south area or from central south to north east. The center of the southern part of the area dominated by the Shawnee National Forest was predicted to have the most suitable habitats for all focal species except for Humulus japonicus and Phragmites australis. The predicted distributions under climate scenarios indicated that species distributions could change or shift under different representative concentration pathways (RCPs) and potential suitable habitat might expand under climate change. Change detection was conducted to quantitatively examine how changing climate could affect invasive species’ potential habitats. The five species with the most species records were evaluated for this analysis. For these species, potential suitable habitats were most likely to expand in the central west of study area for all climate change scenarios. Species suitable habitats would shift under climate change. Functional group and phylogenetic group analyses were conducted to investigate how species groups affect species spatial distributions and how evolutionary related nonnative invasive species distribute spatially. The 17 focal species were grouped into 4 broad functional groups (Woody and shrub species -FG1, herbaceous species -FG2, grass species -FG3, and vine species -FG4) based on life form. AUC indicated that model performance of functional groups was no better than of individual species alone. Land cover was the variable with the largest variable contribution to the predicted distributions of FG1, FG3, and FG4 while maximum temperature had the largest contribution for FG2. Composite maps for the functional groups showed that the central south dominated by the Shawnee National Forest was predicted as the most suitable habitats for all four functional groups. The composite maps for these functional groups were similar to the maps for the individual species within each own functional group. Genetic sequences of each species were used to construct a phylogeny. Besides the 17 focal species, an outgroup species Berberis vulgaris was added into the model to root the phylogenetic tree. Based on the resulting phylogenetic tree, species were classed into 3 groups (superasterids-PG1, monocots-PG2, and superrosids-PG3) based phylogenetic relativeness and distance. AUC indicated that model performance of phylogenetic groups was no better than of individual species alone. Variable contributions of functional groups indicated that landcover was the most significant variable for all three PGs. Composite maps showed the central south was predicted as hotspot. Phylogenetically related species responded similarly to the single species. This study focused on the prediction of non-native invasive species distributions in relation to environmental variables. Environmental factors that significantly affect invasive species distributions can indicate natural resource managers when conducting invasive species management is necessary. The approach of studying how invasive species respond to climate change can be extended to other invasive species research. By integrating functional groups and phylogenetic groups into species distribution predictions, species with too few records for modeling can be examined with abundant species in the same functional or phylogenetic group in predicting distributions. However, this research did not study how interspecific interactions (i.e, competition) between native and invasive species would affect species invasion. Further research of intergrating biotic factors is needed.
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Johannesson, Karin. "Analysis of phosphorus retention variations in constructed wetlands receiving variable loads from arable land." Licentiate thesis, Linköping University, Linköping, Sweden, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-20140.
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Jonas, Altouise Glowdean. "The influence of persons and marketing related variables on consumers purchasing of environmentally-friendly products." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1011098.
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The human environment is under serious threat as natural resources such as air, water and forests are being overused. Worldwide, people have become more aware of the threatening situation and consequently many more individuals are showing concern for the environment. Often this concern is not displayed in consumers’ purchasing behaviour, as consumers who claim to be concerned about the environment are not necessarily consuming or showing a preference for environmentally–friendly products. This study examined two sets of variables, namely, person related and marketing related factors, and determined the extent to which these factors influence consumers’ behaviour when buying environmentallyfriendly products. The empirical data was collected by means of a survey, using self-administered questionnaires distributed to adult employed consumers residing in Port Elizabeth. Two hundred usable questionnaires were received. Three person related factors, namely, norms, environmental concern and environmental knowledge, and four marketing related factors, namely, price, product, place and promotion - were found to influence respondents’ behaviour when purchasing environmentally-friendly products. Environmental concern explained the largest portion of variation in purchase behaviour, while promotion explained the smallest portion of variation. Significant differences in the influence of age were found for norms, nvironmental concern, environmental knowledge and price. It is recommended that suppliers of environmentally-friendly products should ensure that these products are located at outlets which are convenient to consumers; more should be done by the relevant stakeholders to increase environmental knowledge and educate South Africans about the benefits of leading a more environmentally-friendly lifestyle; marketers find more innovative methods to convince consumers to act on their environmental concern; further attempts be made to minimise the price difference between environmentally-friendly products and traditional products; marketers should pay more attention to advertisements promoting environmentally-friendly products to ensure that these appeal to their target markets; and the performance of environmentally-friendly products should be on a par with the performance of traditional products.
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Vanrullen, Tristan. "Vers une analyse syntaxique à granularité variable." Phd thesis, Université de Provence - Aix-Marseille I, 2005. http://tel.archives-ouvertes.fr/tel-00142086.
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Il est souhaitable qu'une analyse syntaxique -en traitement automatique des langues naturelles- soit réalisée avec plus ou moins de précision en fonction du contexte, c'est-à-dire que sa granularité soit réglable. Afin d'atteindre cet objectif, nous présentons ici des études préliminaires permettant d'appréhender les contextes technique et scientifique qui soulèvent ce problème. Nous établissons un cadre pour les développements à réaliser et pour leur évaluation. Nous choisissons un formalisme d'analyse par satisfaction de contraintes (celui des Grammaires de Propriétés) ayant l'avantage de permettre l'utilisation des mêmes ressources linguistiques avec un degré de précision réglable. Nous introduisons une reformulation mathématique du formalisme des Grammaires de Propriétés et nous définissons une mesure (la densité de satisfaction), qui permet de contrôler la granularité de l'analyse. Puis nous décrivons un ensemble d'outils modulaires (LPLSuite) et de ressources (lexique et sous-lexiques DicoLPL) développés pour permettre une analyse syntaxique et susceptibles d'être embarquésdans des applications de haut niveau. Nous présentons et évaluons ensuite plusieurs analyseurs syntaxiques dans ce formalisme, le dernier (SeedParser) étant destiné à mettre en oeuvre une véritable analyse à granularité variable. L'évaluation de ces outils est l'objet d'une étude approfondie. Enn, nous présentons quelques applications développées à l'aide de nos outils.
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Souri, Davood. "Theoretical and Applied Essays on the Instrumental Variable Method." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/28765.
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This dissertation is intended to provide a statistical foundation for the IV models and shed lights on a number of issues related to the IV method. The first chapter shows that the theoretical Instrumental Variable model can be derived by reparameterization of a well-specified statistical model defined on the joint distribution of the involved random variables as the actual (local) data generation process. This reveals the covariance structure of the error terms of the usual theory-driven instrumental variable model. The revealed covariance structure of the IV model have important implications, particularly, for designing simulation studies.
Monte Carlo simulations are used to reexamine the Nelson and Startz (1990a) findings regarding the performance of IV estimators when the instruments are weak. The results from the simulation exercises indicate that the sampling distribution of ^Î IV is concentrated around ^Î OLS.
The second chapter considers the underlying joint distribution function of the instrumental variable (IV) model and presents an alternative definition for the exogenous and relevant instruments. The paper extracts a system of independent and orthogonal equations that covers up a non-orthogonal structural model and argues that the estimated IV regression is well-specified if the underlying system of equations is well-specified. It proposes a new instrument relevancy measure that does not suffer from the first-stage R² deficiencies.
Third chapter argues the application of the IV method in estimation of models with omitted variable. The paper considers the implicit parametrization of statistical models and presents five conditions for an appropriate instruments. Two of them are empirically measurable and can be tested. This improves the literature by adding one more objective criterion for the selection of instruments. This chapter applies the IV method to estimate the rate of return to education in Iran. It argues that the education of two cohorts of Iranians was delayed or cut short by the Cultural Revolution. Therefore, the Cultural Revolution, as an exogenous shock to the supply of education, establishes the year of birth as the exogenous and relevant instrument for education. Using the standard Mincerian earnings function with control for experience, ethnicity, location of residence and sector of employment, the instrumental variable estimate of the return to schooling is equal to 5.6%. The estimation results indicate that the Iranian labor market values degrees more than years of schooling.Ph. D.
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Karoubi, Martine. "Système de raisonnement en langage naturel guidé par un raisonnement caricatural." Paris 11, 1986. http://www.theses.fr/1986PA112373.
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Cette thèse présente un système de raisonnement en langage naturel. Une première partie est consacrée à l’exposé d’un système de question-réponse en langage naturel. Les principales caractéristiques de ce système sont de ne pas utiliser de représentation interne et de raisonner à l’aide de règles de production contextuelles. Nous comparons la méthodologie utilisée à l’approche systèmes experts. La seconde partie étudie la coopération entre deux stratégies de raisonnement, coopération qui a pour but de réduire la combinatoire. En effet, ce système de question-réponse est guidé par un raisonnement caricatural. La caricature est une stratégie de raisonnement qui manipule des concepts abstraits et propose un plan de résolution. Des axes de solutions éventuelles sont ainsi dégagés. Il s’agit d’exploiter les résultats de la stratégie caricaturale et de valider ou d’invalider, par un examen plus raffiné, les solutions qu’elle proposeThe work presented here is our contribution to a question-answering system. The object of this work is twofold: First we present a new version of an answering strategy built around a natural language like representation. This system uses contextual production rules to build a reasoning tree which is the answer to the question. Among other technical features, we use "patterns of rules" to increase the performances of the pattern¬matching algorithm. In the second part we describe a mechanism for exploiting the results of a strategy called "caricature". We refine abstract caricatural reasoning paths in real fine-grain reasonings. We use the caricatural classes to choose "transparent rules" and we also compare phrases to detect the main differencies that have to be reduced
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Cummings, Michael Alan. "Acculturation, Family Variables, and Cognition of a Subgroup of American Indian Children Ages 3-9." DigitalCommons@USU, 1997. https://digitalcommons.usu.edu/etd/6095.
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A study was conducted to examine the relationship between specific family variables and measures of cognitive abilities for preschool and young school-aged children of an American Indian ancestry. More specifically, the study used two cognitive measures, the Kaufman Assessment Battery for Children and the Embedded Figures Test, and examined the influence that 23 family variables and cultural background (acculturation) had on measures of spatial abilities.
Past studies suggested that American Indian children, as a group, perform above the standardization sample on measures of visual-spatial skills, have higher simultaneous processing skills, and are more field independent. It was anticipated that at least 40% of the children tested in this study would have statistically significant discrepancy scores in favor of the Simultaneous Scale and have an effect size of .40 or above on subtests reported to measure visual-spatial skills. It was further hypothesized that the children of this study would be more field independent (reach an effect size of .67 or higher) and that the Embedded Figures Tests would have correlations of r = .50 or above with the total Simultaneous Scale, Magic Windows, Gestalt Closure, Triangles, and Spatial Memory.
Results found that 40% of this sample did not obtain significant discrepancy scores, and only Gestalt Closure for the preschool children and Spatial Memory for the school-aged children reached an effect size of .40. In addition, only school-aged children were considered more field independent, and field independence was associated with the total Simultaneous Scale, the Mental processing Composite, the Achievement Scale, and the following subtests: Triangles, Arithmetic, and Reading/Understanding.
A principal component analysis was conducted to determine the factor structure of the Acculturation Scale (the Rosebud Personal Opinion Survey). This analysis found that the survey lacked empirical support for the dimensions suggested by the authors and only the first component, Language-Ancestry, was a useful indicator of acculturation. Nine family variables and the Language-Ancestry component were used as independent variables and accounted for or predicted the visual-spatial scores of American Indian children. None of the variables used reached a significance level of p ≤ .0056
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Wilson, Robin M. "Influence of demographic variables on the likelihood of management plans for land trust properties." Muncie, Ind. : Ball State University, 2009. http://cardinalscholar.bsu.edu/678.
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Camacho, Mark A. "Depth analysis of Midway Atoll using Quickbird multi-spectral imaging over variable substrates." Thesis, Monterey California. Naval Postgraduate School, 2006. http://hdl.handle.net/10945/2674.
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Shallow water bathymetry is important for both safe navigation and natural resource management purposes. Extracting depth information from spectral imagery allows identification of benthic features and characterization of coral reef habitats, especially in remote islands. Techniques have been developed to extract water depth from multispectral imagery (Lyzenga, 1978; Philpot, 1989). These techniques can be difficult to apply in optically shallow waters with heterogeneous bottom types and varying albedo, and require tuning of multiple parameters. An improved algorithm to extract water depth from multispectral satellite imagery was proposed by Stumpf et al. (2003) to generate bathymetric maps with limited a priori information. The algorithm is based on the ratios of transformed reflectance values in the visible bands, retrieving greater depths than previous algorithms and compensating for variable bottom type and albedo. This method requires fewer tunable parameters and can be applied to low-albedo features. Although Stumpf et al. (2003) conclude that the method is robust and works well over variable bottom types, recent studies have pointed out limitations, mostly attributable to varying albedo (Clark, 2005; Densham, 2005). This research attempts to quantify the contribution of variable benthic substrates to the algorithmâ s accuracy by classifying the scene into its main bottom types and tuning the coefficients separately. The algorithm is evaluated using a QuickBird high resolution multispectral image of the remote Midway Atoll, in the Northwestern Hawaiian Islands. Classifying the image into two main bottom types and tuning the coefficients separately produced a small improvement in the accuracy of the bathymetric estimates when bottom reflectance is included as a factor. This result indicates that Stumpf et al. (2003)â s ratio method is not insensitive to variable bottom type, and that knowledge of the distribution and extent of different benthic substrates in optically shallow waters has the potential to improve bathymetric derivation in remote coastal areas such as coral reef environments in the Pacific.
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Ndoye, Idrissa. "Isolement et approche synthétique de produits naturels issus du champignon endophyte Paraconiothyrium variabile." Paris 6, 2012. http://www.theses.fr/2012PA066314.
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Paraconiothyrium variabile est un champignon endophyte isolé du conifère Cephalotaxus harringtonia et a révélé un antagonisme significatif contre des phytopathogènes communs. Nous avons entrepris la caractérisation chimique des métabolites fongiques impliqués dans la relation mutualiste entre cette plante hôte et le champignon endophyte afin d'étudier leur rôle éventuel dans cet antagonisme. Le fractionnement de l'extrait AcOEt du filtrat de culture de P. Variabile a révélé quatre principales familles de métabolites : α-tétralones, isocoumarines, isobenzofuranes et cyclodipeptides dans des conditions de culture différentes. La configuration absolue des trois α-tétralones portant un hydroxyle en C-4 a été déterminée comme S par analyse de leurs spectres de dichroïsme circulaire. La biotransformation de la juglone et de l'isosclérone par P. Variabile a permis d’augmenter les quantités d'isosclérone et d’obtenir des analogues structuraux, respectivement. Des essais de dimérisation de l'isosclérone en milieu acide ont été réalisées vers le squelette naturel spirobisnaphtalène de type palmarumycine. Par ailleurs, un travail annexe apporte une contribution supplémentaire à la synthèse du précurseur linéaire des hirsutellonesParaconiothyrium variabile is an endophytic fungus isolated from the conifer Cephalotaxus harringtonia and displayed a significant antagonism against common plant pathogens. We undertook the chemical characterization of the fungal metabolites implied in the mutualistic relationship between the host plant and the endophyte in order to study their role in the observed antagonism. The analysis of the AcOEt extract of the culture filtrate of P. Variabile revealed four main families of metabolites: α-tetralones, isocoumarin, isobenzofuran, and a cyclodipeptide obtained in different culture conditions. The absolute configuration of three α-tetralones with a hydroxyl at C-4 was determined S by analysis of their circular dichroism spectra. The biotransformation of juglone and isosclerone led to increased amount of isosclerone and structural analogues, respectively. Dimerization of isosclerone under acidic conditions gave the best results towards the natural spirobisnaphtalene skeleton of palmarumycins. Additionally, a contribution to the synthesis of a biomimetic linear precursor of hirsutellones was done
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Chidurala, Manohar. "A Numerical Study of Unsteady Natural Convection in a Rectangular Enclosure -- The Effect of Variable Thermodynamic and Transport Properties." ScholarWorks@UNO, 2009. http://scholarworks.uno.edu/td/973.
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A two-dimensional mathematical model is adopted to investigate the development of buoyancy driven circulation patterns and temperature contours inside a rectangular enclosure filled with a compressible fluid where one of the vertical walls of the enclosure is kept at a higher temperature than the opposite one. Fluid thermodynamic and transport properties are assumed to be functions of temperature. The governing equations are discretized using second order accurate differencing for spatial and temporal derivatives and then linearized using Newton's linearization method. The resulting set of algebraic equations is solved using the Coupled Modified Strongly Implicit Procedure for the unknowns of the problem. The results of this study show that the variable property model predicts lower values for wall heat fluxes and Nu number than the constant property one for Rayleigh numbers between 104 and 105.
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Said, Maryam Darwesh. "Epidemic cholera in KwaZulu-Natal the role of the natural and social environment /." Thesis, Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-12082006-124732.
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Holmqvist, Stephanie. "Comparison of Two Methods for Detecting Intrathecal Synthesis of Borrelia Specific Antibodies." Thesis, Linnaeus University, School of Natural Sciences, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-7868.
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In Europe, Lyme disease is caused by the species Borrelia (B.) burgdorferi sensu stricto, B. garinii and B. afzelii. The disease is the most common vector-borne infection in Europe and the United States, and the resulting manifestation can involve the skin, nervous system, heart and joints. The symptoms that arise are associated with the Borrelia species causing the infection. The species most associated with neuroborreliosis is B. garinii whilst B. burgdorferi sensu stricto is associated with arthritis and B. afzelii is associated with dermatological symptoms. Lyme disease normally has three phases in untreated patients. The first phase is characterised by erythema migrans, a reddening of the skin around the area of the tick bite. If the disease develops to the second phase the patient will suffer from neuroborreliosis which is characterised by neurological symptoms such as headache and peripheral facial paralysis. Cerebrospinal fluid (CSF) analysis is used to diagnose neuroborreliosis. The diagnosis is complicated by variations between the different Borrelia species and that many healthy individuals have antibodies directed against Borrelia. Antibodies in CSF can be found in different diseases. The antibodies can be produced in the central nervous system or come across the blood-brain barrier and thus derive originally from the blood. By measuring the concentration of total albumin in serum and in CSF it can be determined if the antibodies present in the CSF have been produced in the central nervous system or if they originate from the blood. The typical manifestation in the last phase of Lyme disease is severe arthritis. The aim of this examination project was to compare two ELISAs for detection of antibodies directed to Borrelia. Indirect ELISAs from DAKO and Euroimmun were compared for the diagnosis of neuroborreliosis in 100 individuals. Borrelia specific antibodies of class IgM or IgG were found in 16 of 100 patients by DAKO’s ELISA and in 20 of the same 100 patients by Euroimmun’s ELISA. The reason that Euroimmun’s method detected more cases of neuroborreliosis is probably that this method detects antibodies directed to all three pathological species of Borrelia while DAKO’s method only detects antibodies directed to B. burgdorferi. In conclusion, this study indicates that Euroimmun’s method to detect antibodies of class IgM and IgG directed to Borrelia is superior to DAKO’s method. The obtained results were confirmed by Western blot analysis which gave results in accordance with those of Euroimmun’s ELISA.
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Cayani, Banda Alexia Gabriela, and Gutiérrez Adriana Leofel Montenegro. "Principales variables que intervinieron en el desarrollo de la exportación de gas natural de camisea durante el periodo 2000 - 2018." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/651665.
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El presente trabajo de investigación busca analizar las variables principales que intervinieron en el desarrollo de la exportación de gas natural de Camisea durante el periodo 2000 - 2018. Para ello, a lo largo del proceso, se identificó como indispensable plantear como objetivo principal, comprender la relevancia del mercado internacional frente al mercado local para el desarrollo de la exportación del gas de Camisea durante el periodo 2000 – 2018.
La elaboración del estudio, se realizó en base al método científico, y para su desarrollo se aplicó el diseño cualitativo exploratorio de tipo estudio de caso. Por un lado, los pasos para el manejo de la información primaria fueron la búsqueda de antecedentes epistemológicos en bases de datos destacadas, bases de datos bibliométricas y bancos de datos, todas fuentes confiables y reconocidas; asimismo, la búsqueda de bases teóricas que respaldasen el tema de investigación; también, la detección de una realidad problemática que pusiese en evidencia el problema principal y problemas específicos; además, el planteamiento de argumentos válidos que justificasen el estudio en cuestión; y finalmente, el análisis de documentos que contuvieran información numérica y datos estadísticos del sector objeto de estudio. Por otro lado, para la obtención de la información primaria se realizaron diecisiete entrevistas semi estructuradas a expertos de once empresas distintas, tanto públicas como privadas, las cuales forman parte del proyecto Camisea. Para el procesamiento de dicha información, se utilizó el software Atlas.ti® y la técnica de triangulación de datos, contrastando los antecedentes, la información contenida en el marco teórico y el resultado de las entrevistas.
Finalmente, las principales variables que intervinieron en el desarrollo de la exportación del gas natural de Camisea durante el periodo 2000 – 2018, fueron: la poca demanda nacional, el volumen de reservas probadas, el precio internacional, los ingresos por regalías, la inversión en infraestructura, el desarrollo tecnológico y el marco contractual. Con los resultados del estudio, se busca contribuir a futuras investigaciones que pretendan abordar el tema de investigación, ya sea desde la misma, u otra perspectiva.This research paper seeks to analyze the main variables that intervened in the development of Camisea's natural gas exports during the period 2000 - 2018. For this, throughout the process, it was identified as essential to propose as a main objective, to know the relevance of the international market compared to the local market for the development of the Camisea gas export project during the period 2000 - 2018. The elaboration of the study was carried out based on the scientific method, and for its development, was applied the qualitative exploratory design of the case study type. On one hand, the steps for handling the primary information were, the search for epistemological antecedents in outstanding databases, bibliometric databases and databanks, all reliable and recognized sources; likewise, the research for theoretical bases that would support the subject of study; also, the detection of a problematic reality that would highlight the main and specific problems; in addition, the raising of valid arguments that would justify the investigation; and finally, the analysis of documents containing numerical information and statistical data of the sector under study. On the other hand, in order to obtain the primary information, eighteen semi-structured interviews were carried out with experts from eleven different companies, public and private, which are part of the Camisea project. To process this information, the Atlas. ti® software and the data triangulation technique were used, contrasting the background, the information contained in the theoretical framework and the result of the interviews. Finally, the main variables that intervened in the development of Camisea's natural gas exports during the period 2000 - 2018 were: the low domestic demand, the volume of proven reserves, the international price, the income from royalties, the investment in infrastructure, the technological development and the contractual framework. With the results of the study, we seek to contribute to future research that seeks to address the research topic, either from the same or another perspective.
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Dömeland, Narvaez Dörte. "Empirical studies on human capital and natural resources." Doctoral thesis, Universitat Pompeu Fabra, 2006. http://hdl.handle.net/10803/7345.
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El primer capítulo de la tesis sobre "Estudios Empíricos sobre Capital Humano e Instituciones" presenta estimaciones de retornos a la educación en Alemania y analiza los determinantes de las preferencias educativas. El segundo capítulo utiliza estimaciones de retornos a la experiencia en el país de origen de inmigrantes en Estados Unidos para proporcionar evidencia empírica que el comercio aumenta la acumulación de capital humano en el trabajo, incluso en los países menos desarrollados, resolviendo la ambigüedad teórica si el comercio aumenta o disminuye "learning-by-doing". La acumulación de capital humano en el trabajo es también positivamente asociada con el PIB per capita, un alto nivel de educación y una mayor calidad de políticas e instituciones. El último capítulo analiza el efecto de recursos naturales y asistencia externa sobre la calidad de instituciones, proporcionando evidencia empírica que -contrario a la asistencia externa, la abundancia de mineral y combustible tiende a ser asociada negativamente con la calidad de instituciones si la fragmentación étnica es grande.The first chapter of the thesis on "Empirical Studies on Human Capital and Institutions" presents estimates of returns to education in Germany and analyses the determinants of educational choices. The second chapter uses estimated returns to home country experience of US immigrants to provide empirical evidence that trade increases on-the-job human capital accumulation even in less developed countries, thereby resolving the theoretical ambiguity whether trade increases or decreases learning-by-doing. Similar to trade, GDP per capita, a high average level of educational attainment and stronger quality of policy and institutions are found to be positively associated with on-the-job human capital accumulation. The last chapter analyses the effect of natural resources and aid on institutions, providing empirical evidence that contrary to aid, mineral and fuel abundance tends to be associated with significantly lower quality of institutions if ethnic fractionalization is large.
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Thomazini, Luís Fernando Viviani. "Estudo do comportamento da temperatura e da umidade relativa do ar no interior de um secador solar misto de ventilação natural." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/11/11152/tde-28092015-172717/.
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A utilização de secadores de produtos agrícolas é oportuna às necessidades do pequeno produtor rural, pois o produto desidratado possui maior valor agregado em relação ao mesmo produto fresco, requer menor espaço de armazenamento e tem maior durabilidade. É necessário, no entanto, oferecer ao produtor familiar equipamentos economicamente viáveis e, se possível, que utilizem recursos naturais e renováveis como fonte de energia, aliando sustentabilidade e crescimento econômico. Diante disso, os objetivos foram estudar o comportamento da temperatura e da umidade relativa do ar no interior de um secador solar misto de ventilação natural em função das condições meteorológicas externas, e os períodos e épocas do ano mais ou menos favoráveis ao processo de secagem, em função da combinação das variáveis meteorológicas. Pode-se concluir que nem sempre elevados valores de radiação resultam em elevados valores de temperatura dentro do secador. Dias nublados e, principalmente chuvosos, comprometem mais o desempenho do secador do que, por exemplo, as perdas térmicas decorrentes da velocidade do vento que o circunda. O secador cumpre o papel de manter sua temperatura maior que a temperatura externa, predominantemente, entre 06h e 18h, enquanto que no restante do dia o comportamento da temperatura e da umidade relativa, dentro e fora do equipamento, assemelha-se. Períodos com elevada incidência solar e pouca chuva são os mais favoráveis à secagem. No entanto, é possível que meses de inverno e de pouca chuva tenham melhor desempenho do que meses situados ou próximos do verão que possuam dias nublados e chuvosos constantemente.The use of dryers to dehydrate agricultural products is appropriate to the needs of small farmers, because the dehydrated product has higher added value compared to the fresh ones, requires less storage space and lasts longer. It is necessary, however, offer to the small farmer economically viable equipment and, if possible, using natural and renewable energy sources , combining sustainability and economic growth. Therefore, the objectives were to study the behaviour of temperature and relative humidity inside a mixed-mode solar dryer with natural ventilation due to external weather conditions. And also the periods more or less favorable to the drying process, depending on the combination of meteorological variables. It was concluded that not always higher solar radiation results in higher temperature values inside the dryer. Cloudy and mainly rainy days may disturb the performance of the dryer, more than, for example, thermal losses due to the wind speed surrounding it. The data showed also that It was possible for the dryer to maintain its temperature higher than the outside temperature, predominantly between 06h and 18 h, while in the rest of the day the behaviour of temperature and relative humidity inside and outside of the equipment, resembles. Periods of high sunlight intensity and little rain are the most favorable to drying. However, winter months with little rain may present better performance than months situated near or in the summer but having cloudy and rain constantly.
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Kossowska, Nicole. "Utvärdering av enterokockdiagnostik : Identifiering av vancomycin - variabla enterokocker." Thesis, Malmö universitet, Fakulteten för hälsa och samhälle (HS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-43741.
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De grampositiva bakterierna enterokocker tillhör normalfloran i tarmen hos människor samt djur. I detta arbete studeras vancomycin-variabla enterokocker (VVE) som är vanA positiva enterokocker, känsliga för vancomycin och kan utveckla resistens in vivo. Vancomycin-resistenta enterokocker (VRE) består av två arter bakterier Entrococcus faecalis och Enterococcus faecium. VVE består av Enterococcus faecium och är svåra att detektera med odlingsbaserad diagnostik och kan därför leda till att bakterien är underdiagnostiserad, samt att den tyst kan sprida sig inom sjukhusmiljön. VVE har en förmåga att kunna övergå från vancomycin-variabla till att vara vancomycin-resistenta fenotyper. Därför undersöks i denna studie vid vilken vancomycinkoncentration (5, 4, 3, 2 mg/L) som VVE kan anrikas i buljongerna inför amplifiering med hjälp av real-time polymerase chain reaction (real-time PCR). Resultatet visade att vancomycinkoncentrationen skulle behövas sänkas till 2 mg/L, dock kan bakgrundsfloran vara för hög vid denna koncentration av antibiotika.The Gram-positive bacteria Enterococci, belong to the normal intestinal flora in humans and in animals. In the following study, vancomycin-variable enterococci (VVE) are investigated. VVE is a vanA-positive bacteria, meaning that they are sensitive to vancomycin and can develop a resistance in vivo. Vancomycin-resistant enterococci (VRE) consists of two different species of bacteria, Enterococcus faecalis and Enterococcus faecium. Furthermore, VVE consists of E. faecium and can be difficult to detect with a culture-based diagnostic andcan therefore lead to the bacterium being underdiagnosed. This in turn means that the bacteria can be quietly spread within the hospital. VVE has a unique ability, it can transition from vancomycin-variables to having vancomycin-resistant phenotypes. Therefore, this study investigates at what vancomycin concentration the VVE broths can be enriched in the broths before the qPCR. The results show that the vancomycin concentration is optimal at 2 mg/L. However, for the background flora this might be a too high concentration.
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Franco, Camila Manara. "Determinação de hidrocarbonetos majoritarios presentes no gas natural utilizando espectroscopia no infravermelho proximo e calibração multivariada." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250570.
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Orientador: Jarbas Jose Rodrigues RohwedderDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: Através da Espectroscopia de Infravermelho Próximo (NIR), auxiliada por quimiometria, foram desenvolvidos modelos de calibração para determinar a concentração de hidrocarbonetos majoritários em misturas gasosas cujas concentrações são semelhantes a aquelas observadas em gás natural. Os espectros foram obtidos em dois diferentes espectrofotômetros NIR construídos no próprio laboratório, os quais empregavam células de caminho óptico fixo e variável. Diferentes conjuntos de amostras foram preparados de forma a reproduzir a variabilidade de concentração de metano, etano, propano e butano encontrada nas diversas fontes de gás natural. A análise de amostras certificadas, através dos modelos de calibração, apresentou valores para a raiz do erro médio quadrático de previsão (RMSEP) iguais a 1,07, 0,21, 0,22 e 0,14 % (v/v) na determinação de metano, etano, propano e butano, respectivamente. A previsão do gás metano apresentou melhor repetibilidade quanto realizada pela espectroscopia NIR do que com a técnica padrão, cromatografia gasosa. Visando a possibilidade da construção de um espectrofotômetro NIR dedicado à análise de gás natural foi realizado um estudo de seleção de variáveis, cujo resultado indicou que, utilizando até 13% do número inicial de variáveis (280) é possível realizar a previsão dos hidrocarbonetos gasosos sem perda da qualidade analítica quando comparado à análise que utiliza a faixa espectral completa. Por meio dos comprimentos de onda selecionados, pode-se prever a concentração de metano, etano, propano e butano com valores de RMSEP iguais a 1,32, 0,41, 0,22 e 0,14 % (v/v), respectivamente.
Abstract: Near Infrared (NIR) Spectroscopy and Chemometrics were used to construct calibration models to determine the concentration of major hydrocarbons in gas mixtures in concentrations similar to those observed in natural gas. The spectra were obtained by two different NIR spectrophotometers made in the laboratory, one employing a cell of fixed and other with variable optical path. Different sample sets were prepared in order to mimic the variability of methane, ethane, propane and butane concentration found in natural gas obtained from various sources. The analysis of certified samples made by using the calibration models showed Root-Mean-Square Errors of Prediction (RMSEP) equal to 1.07, 0.21, 0.22 and 0.14% (v/v) for methane, ethane, propane and butane determination, respectively. The prediction of methane gas content showed better repeatability compared to the standard technique based on gas chromatography. To investigate the possibility of constructing an NIR spectrometer dedicated to the analysis of natural gas, the selection of variables was evaluated. The results indicated that, by using up to 13% of the initial variables, the prediction of hydrocarbon gases is achieved with the same quality when compared to the results obtained using the full spectral range. Employing the selected wavelengths, it is possible to predict the concentration of methane, ethane, propane and butane with values of RMSEP equal to 1.32, 0.41, 0.22 and 0.14% (v / v), respectively.
Mestrado
Quimica Analitica
Mestre em Química
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Braly, S. Katharine. "Environmental variables influencing sexual reproduction of sea oats, Uniola paniculata (Poaceae) across a natural dune field on Bear Island, North Carolina." View electronic thesis (PDF), 2009. http://dl.uncw.edu/etd/2009-1/r1/bralys/sbraly.pdf.
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Girard, Alexandre 1987. "Fast and strong lightweight robots based on variable gear ratio actuators and control algorithms leveraging the natural dynamics." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111689.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 191-196).
In many applications, robots have to bear large loads while moving slowly and also have to move quickly through the air with almost no load. These type of bi-modal tasks, with conflicting requirements in terms of operating speeds and desired impedances, often lead to the use of oversized and inefficient actuators which are inhibitory particularly for mobile robots. Multiple gear ratios, like in a powertrain, address this issue by allowing an effective use of power over a wide range of output speeds, by enabling significant changes to the reflected intrinsic actuator impedances and by making possible the leveraging or attenuation of the natural load dynamics. This thesis aims to develop the technological solutions needed to use variable gear ratio actuators and exploit the advantages of variable transmissions in a robotic context. First, by addressing the issue of how to make fast and seamless gearshifts between two very different reduction ratios under diverse load conditions, with a solution based on a dual-motor actuator architecture and a control scheme using the null space. Second, by developing control algorithms that select optimal gear ratios dynamically based on state feedback, to move with minimal motor torques and to adjust the output impedance appropriately given a task. The proposed approach exploit variable transmissions not merely for increasing maximum torque and speed, but also to significantly alter the dynamic properties, including load sensitivity, robustness, and backdrivability. Simulations and experiments using a novel lightweight robotic arm using three custom-built dual-speed dual-motor actuators are presented. Results demonstrate very fast gear shifting in highly dynamic situations with dual-speed dual-motor actuators, and show that actively changing gear ratios using the proposed control algorithms can lead to an order-of-magnitude reduction of necessary motor torque and power.
by Alexandre Girard.
Ph. D.
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Agustini, José Antonio. "Extratos vegetais obtidos de espécies nativas do Cerrado brasileiro no controle do ácaro-rajado (Tetranychus urticae Koch) /." Ilha Solteira, 2017. http://hdl.handle.net/11449/151887.
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Orientador: Marineide Rosa VieiraResumo: O ácaro rajado, Tetranychus urticae Koch, é uma praga que ataca várias culturas em todo o mundo. Seu controle é feito basicamente por acaricidas químicos sintéticos. O uso inadequado de defensivos agrícolas, além de acarretar problemas ao meio ambiente, ao trabalhador e ao consumidor, pode levar ao desenvolvimento de populações de pragas resistentes aos seus princípios ativos. Extratos vegetais têm sido estudados na busca de novos princípios ativos que causem menos problemas ambientais, ocupacionais e de saúde humana, e que possam fazer parte de programa de manejo integrado de pragas e doenças. As florestas brasileiras são constituídas por uma grande diversidade de plantas que podem apresentar metabólitos secundários interessantes com propriedades biocidas. O objetivo deste estudo foi avaliar extratos aquosos e hidroetanólicos de folhas e cascas de doze espécies vegetais nativas do Cerrado brasileiro quanto à atividade acaricida e ao efeito sobre a fecundidade de fêmeas do ácaro-rajado, T. urticae. De cada espécie vegetal foram avaliados dois órgãos (folhas e cascas), duas épocas de coletas (primavera/verão e outono/inverno) além de dois tipos de solventes (água e etanol 70%). Os extratos foram aplicados por pulverização em torre de Potter, avaliando-se mortalidade, repelência e oviposição após 120 horas. Todas as doze espécies apresentaram atividade acaricida significativa sobre T. urticae, dependendo da época de coleta, do material vegetal e do solvente utilizado. Em nove e... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The two-spotted spider mite, Tetranychus urticae Koch, is a pest that attacks various crops throughout the world. The mites control is basically made by synthetic chemical acaricides. The inappropriate use of pesticides, besides causing problems to the environment, to the workers and the consumers, can lead to the development of populations of pests resistant to its active ingredient. Some pesticides such as neonicotinoids and pyrethroids have their origin in secondary plant metabolites such as tobacco and chrysanthemum, respectively. Plant extracts have been studied in the search for new active ingredients that cause less environmental, occupacional and human health problems, and that can be part of an integrated pest and disease management program. The Brazilian forests are constituted by a great plant diversity that can have interesting secondary metabolites with biocide properties. The objective of this study was to evaluate the mitecide activity of the aqueous and hydroethanolic extracts of leaves and bark of twelve native species from the Brazilian Cerrado and their effect on the fecundity of T. urticae mite females. Two plant organs (leaves and barks), two collection seasons (spring/summer and autumn/winter) were evaluated from each plant species, besides two types of solvents (70% ethanol and water). The extracts were applied by Potter tower spray, evaluating mortality, repellency and oviposition after 120 hours. All twelve species showed significant miticide activity... (Complete abstract click electronic access below)
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Derrington, Kathryn. "Comparative analysis of perceptions of metacognitive processes in traditional school leavers and mature age entry students in their first year of university education." Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16443/1/Kathryn_Derrington_Thesis.pdf.
Full textAbstract:
Within the educational psychology literature there is an abundance of research in the field of metacognition. The concentration of this research however has been in primary and secondary school contexts with little attention given to tertiary students' understanding or use of metacognition; there has been even less attention to whether age is a factor in tertiary students' perceptions of their metacognitive processes.
The primary purpose of this study was to explore the perceptions of two distinct groups of first year university students, towards their understanding and usage of metacognitive processes and strategies. The two groups defined were traditional school leavers and mature age students. The findings from the exploration of these perceptions were compared to ascertain the similarities and differences in metacognitive processes between the two cohorts.
The data collected for this study were obtained through a process of individual face-to-face in- depth interviews. The choice of this methodology was deliberate in order to gather rich data about the students' perceptions and experiences rather than attempt to measure their levels of metacognition against some predetermined standard.
Data were collected and analyzed on the two constructs of metacognition which were identified in the literature search. These were metacognitive knowledge and metacognitive control. A range of affective variables such as self efficacy, motivation and expectancy of success, which impact on students' metacognitive abilities and processes, were also considered in the data collection and analysis.
The findings indicated that age was a factor in determining some differences and similarities in students' perceptions of their own and others metacognitive processes. In certain cases the traditional school leavers' recency of experience with formal study was deemed an advantage; in others the life experience of the mature age students was perceived an advantage. In some instances the age of the student had no discernable impact on their understanding of, and ability to, utilize metacognitive strategies.
These findings assist to broaden the understanding of student perceptions of metacognition in the tertiary context. The findings also make it imperative that tertiary institutions make fewer assumptions about the skills and abilities of their commencing students based on the criterion of age and offer more opportunities to assist students to understand the value of developing and improving their metacognitive processes.