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von Schantz, Torbjörn, Debora Arlt, Staffan Bensch, Dennis Hasselquist i Bengt Hansson. "Breeding synchrony does not affect extra-pair paternity in great reed warblers". Behaviour 141, nr 7 (2004): 863–80. http://dx.doi.org/10.1163/1568539042265699.
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AbstractBreeding synchrony is hypothesised to influence the occurrence and frequency of extra-pair fertilisations (EPFs) in birds irrespective of the social mating system. The two proposed hypotheses make opposite predictions. (1) Synchronous breeding leads to a lower frequency of EPFs because males face a trade-off between mate guarding and obtaining additional matings via extra-pair copulations (EPCs) ('guarding constraint' hypothesis). (2) Synchronous breeding promotes EPFs because females are able to compare displaying males simultaneously, which provides them with more reliable cues for extra-pair mate choice ('mate assessment' hypothesis). In a study of great reed warblers (Acrocephalus arundinaceus) from 1987-1998, annual breeding was asynchronous and the frequency of EPFs was rather low (extra-pair young occurring in 6.4% of the broods). Within this population, however, there was no relationship between the frequency of EPFs and breeding synchrony, thus not favouring any of the two hypotheses. Contrary to assumptions of the hypotheses, mate guarding did not seem to constrain males from engaging in EPCs (disfavouring the 'guarding constraint' hypothesis), and females seem to have repeated opportunities to compare males irrespective of breeding synchrony (disfavouring the 'mate assessment' hypothesis). Our results suggest that breeding synchrony is not an important factor influencing patterns of EPFs in great reed warblers. The low frequency of EPFs may instead be explained by the socially polygynous mating system, where females are less constrained in their choice of a social male.
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Koenig, Walter D., Johannes M. H. Knops, William J. Carmen i Ian S. Pearse. "What drives masting? The phenological synchrony hypothesis". Ecology 96, nr 1 (styczeń 2015): 184–92. http://dx.doi.org/10.1890/14-0819.1.
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Krebs, Charles J., Alice J. Kenney, Scott Gilbert, Kjell Danell, Anders Angerbjörn, Sam Erlinge, Robert G. Bromley, Chris Shank i Suzanne Carriere. "Synchrony in lemming and vole populations in the Canadian Arctic". Canadian Journal of Zoology 80, nr 8 (1.08.2002): 1323–33. http://dx.doi.org/10.1139/z02-120.
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Population fluctuations may occur in synchrony among several rodent species at a given site, and they may occur in synchrony over large geographical areas. We summarize information on synchrony in lemmings and voles from the Canadian Arctic for the past 20 years. The most detailed available information is from the central Canadian Arctic, where snap-trap samples have been taken annually at several sites for periods of up to 15 years. Geographical synchrony in the same species among different sites was strong, especially for the central and eastern Canadian Arctic. Synchrony among different species at a given site was also generally high. When one species is at high density, densities of all species at that site tend to be high. These results do not easily fit the mobile-predator hypothesis proposed to explain regional synchrony, and are more consistent with the weather hypothesis, which we suggest both entrains synchrony among sites and enforces synchrony among species within a site. We tentatively support the weather hypothesis for geographical synchrony in lemmings, and recommend the establishment of a circumpolar program to monitor lemming cycles and predator movements that would advance our understanding of these large-scale patterns of cyclic synchrony.
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Castelhano, João, Inês Bernardino, José Rebola, Eugenio Rodriguez i Miguel Castelo-Branco. "Oscillations or Synchrony? Disruption of Neural Synchrony despite Enhanced Gamma Oscillations in a Model of Disrupted Perceptual Coherence". Journal of Cognitive Neuroscience 27, nr 12 (grudzień 2015): 2416–26. http://dx.doi.org/10.1162/jocn_a_00863.
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It has been hypothesized that neural synchrony underlies perceptual coherence. The hypothesis of loss of central perceptual coherence has been proposed to be at the origin of abnormal cognition in autism spectrum disorders and Williams syndrome, a neurodevelopmental disorder linked with autism, and a clearcut model for impaired central coherence. We took advantage of this model of impaired holistic processing to test the hypothesis that loss of neural synchrony plays a separable role in visual integration using EEG and a set of experimental tasks requiring coherent integration of local elements leading to 3-D face perception. A profound reorganization of brain activity was identified. Neural synchrony was reduced across stimulus conditions, and this was associated with increased amplitude modulation at 25–45 Hz. This combination of a dramatic loss of synchrony despite increased oscillatory activity is strong evidence that synchrony underlies central coherence. This is the first time, to our knowledge, that dissociation between amplitude and synchrony is reported in a human model of impaired perceptual coherence, suggesting that loss of phase coherence is more directly related to disruption of holistic perception.
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Domingues, W. M., L. M. Bini i A. A. Agostinho. "Spatial synchrony of a highly endemic fish Assemblage (Segredo Reservoir, Iguaçu River, Paraná State, Brazil)". Brazilian Journal of Biology 65, nr 3 (sierpień 2005): 439–49. http://dx.doi.org/10.1590/s1519-69842005000300009.
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In this study, patterns of spatial synchrony in population fluctuations (cross-correlation) of an endemic fish assemblage of a Neotropical reservoir (Segredo Reservoir, Iguaçu River, Paraná State, Brazil) were reported. First, the level of population synchrony for 20 species was estimated. Second, population synchrony was correlated, using the Mantel test, with geographical distances among sites (n = 11) and also environmental synchrony (temperature). Nine species presented significant correlations between spatial synchrony and geographic distances (Astyanax sp. b, Astyanax sp. c, Pimelodus sp., Hoplias malabaricus, Crenicichla iguassuensis, Hypostomus derbyi, Hypostomus myersi, Rhamdia branneri, and R. voulezi). Considering the ecology of the species and the significant relationship between population and environmental synchronies, it seems that environmental stochasticity is the most plausible hypothesis in explaining the observed synchrony patterns.
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Costa, Gabriel Nascimento, João Valente Duarte, Ricardo Martins, Michael Wibral i Miguel Castelo-Branco. "Interhemispheric Binding of Ambiguous Visual Motion Is Associated with Changes in Beta Oscillatory Activity but Not with Gamma Range Synchrony". Journal of Cognitive Neuroscience 29, nr 11 (listopad 2017): 1829–44. http://dx.doi.org/10.1162/jocn_a_01158.
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In vision, perceptual features are processed in several regions distributed across the brain. Yet, the brain achieves a coherent perception of visual scenes and objects through integration of these features, which are encoded in spatially segregated brain areas. How the brain seamlessly achieves this accurate integration is currently unknown and is referred to as the “binding problem.” Among the proposed mechanisms meant to resolve the binding problem, the binding-by-synchrony hypothesis proposes that binding is carried out by the synchronization of distant neuronal assemblies. This study aimed at providing a critical test to the binding-by-synchrony hypothesis by evaluating long-range connectivity using EEG during a motion integration visual task that entails binding across hemispheres. Our results show that large-scale perceptual binding is not associated with long-range interhemispheric gamma synchrony. However, distinct perceptual interpretations were found to correlate with changes in beta power. Increased beta activity was observed during binding under ambiguous conditions and originates mainly from parietal regions. These findings reveal that the visual experience of binding can be identified by distinct signatures of oscillatory activity, regardless of long-range gamma synchrony, suggesting that such type of synchrony does not underlie perceptual binding.
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Swindale, Nicholas V. "Neural Synchrony, Axonal Path Lengths, and General Anesthesia: A Hypothesis". Neuroscientist 9, nr 6 (grudzień 2003): 440–45. http://dx.doi.org/10.1177/1073858403259258.
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Sillero-Zubiri, Claudio, Paul J. Johnson i David W. MacDonald. "A Hypothesis for Breeding Synchrony in Ethiopian Wolves (Canis simensis)". Journal of Mammalogy 79, nr 3 (sierpień 1998): 853. http://dx.doi.org/10.2307/1383093.
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Schenkeveld, L. E., i R. C. Ydenberg. "Synchronous diving by surf scoter flocks". Canadian Journal of Zoology 63, nr 11 (1.11.1985): 2516–19. http://dx.doi.org/10.1139/z85-372.
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We studied the diving and surfacing synchrony of foraging flocks of wintering surf scoters (Melanitta perspicillata). Our data support the hypothesis that synchronous diving is an adaptation that reduces kleptoparasitism by glaucous-winged gulls (Larus glaucescens), which frequently attend foraging flocks. We developed a statistical method for measuring and comparing synchrony between flocks, and applied it to videotape records of 30 flocks. The results show that diving and surfacing are highly synchronous, and that there is a large variation between flocks in the degree of synchrony exhibited. The most pronounced effect is for surfacing synchrony to be higher in the presence of gulls. This seems to arise because individual birds curtail their dives so that less synchrony is lost between diving and surfacing during a group dive. This curtailment of dive length may lead to a reduction in the average size of prey captured.
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Ellis, Lisa A., John D. Styrsky, Robert C. Dobbs i Charles F. Thompson. "Female Condition: A Predictor of Hatching Synchrony in the House Wren?" Condor 103, nr 3 (1.08.2001): 587–91. http://dx.doi.org/10.1093/condor/103.3.587.
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Abstract The degree of hatching synchrony in clutches of passerine birds frequently varies among species and among individuals of the same species. Many hypotheses have been proposed to explain why some eggs hatch several days after others in a clutch. We tested one of these hypotheses, the energetic-constraints hypothesis, which proposes that females in poor physical condition postpone initiating incubation and hatch their clutches synchronously, whereas females in good condition begin incubation early and hatch their clutches asynchronously. We tested the hypothesis using the House Wren (Troglodytes aedon) because recent studies have found little difference in productivity between synchronously and asynchronously hatching clutches in this species, suggesting that the degree of hatching synchrony varies for reasons unrelated to nestling growth and survival. We used logistic regression to test the dependence of the degree of hatching synchrony on each of two measures of female condition. We found no relationship between female condition and degree of hatching synchrony. These results and two other lines of evidence are inconsistent with the energetic-constraints hypothesis as an explanation for variation in degree of hatching synchrony in this House Wren population. ¿Predice la Condición de las Hembras la Sincronía de Eclosión en Troglodytes aedon? Resumen. Con frecuencia, el grado de sincronía en la eclosión de nidadas de aves paserinas varía entre especies y entre individuos de la misma especie. Se han propuesto muchas hipótesis para explicar por qué algunos huevos eclosionan varios días después que otros en una misma nidada. Pusimos a prueba una de esas hipótesis, la de las limitaciones energéticas, que propone que hembras en mala condición física postponen el inicio de la incubación y sus nidadas eclosionan sincrónicamente, mientras que aquellas en buena condición inician la incubación temprano y sus nidadas eclosionan asincrónicamente. Pusimos a prueba la hipótesis usando a Troglodytes aedon, pues estudios recientes en esta especie han encontrado pocas diferencias en productividad entre nidadas de eclosión sincrónica y asincrónica, lo que sugiere que el grado de sincronía en la eclosión varía por motivos no relacionados con el crecimiento y supervivencia de los pichones. Utilizamos regresión logística para evaluar el grado de dependencia de la sincronía de eclosión en dos medidas de condición física de las hembras. No encontramos ninguna relación entre la condición de las hembras y el grado de sincronía en la eclosión. Estos resultados y otras dos líneas de evidencia son inconsistentes con la hipótesis de las limitaciones energéticas como una explicación para la variación en el grado de sincronía de eclosión en esta población de T. aedon.
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Hamel, Lauren M., Robert Moulder, Susan Eggly, Terrance Lynn Albrecht, Steven Boker, David W. Dougherty i Louis Penner. "Comparing nonconscious nonverbal synchrony in racially concordant and racially discordant oncology interactions." Journal of Clinical Oncology 37, nr 27_suppl (20.09.2019): 169. http://dx.doi.org/10.1200/jco.2019.37.27_suppl.169.
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169 Background: Communication in racially discordant (Black patient, non-Black physician) oncology interactions, which constitute about 80% of Black patients’ interactions, is generally poorer than in racially concordant interactions, and likely contributes to treatment disparities. However, the nonverbal behaviors that contribute to this problem are largely unknown. We examined nonverbal synchrony, or the nonconscious coordination of movement, which can reflect relationship quality. We hypothesized that racially discordant interactions will have lower levels of nonverbal synchrony. Methods: Data include video recordings of 68 Black patients and 163 White patients discussing treatment with their non-Black oncologists. Recordings were submitted to motion detection software to measure nonverbal synchrony. This software measures global synchrony (all correlated motion), peak synchrony (all positively correlated motion), who is leading the interaction (similar to who is leading in ballroom dancing), and how much synchrony occurs based on who is leading the interaction. Using multi-level models, we investigated whether nonverbal synchrony differed in racially concordant and racially discordant dyads. Results: Findings showed greater levels of global synchrony (p < .05) and greater peak synchrony (p < .05) in racially discordant interactions compared to racially concordant interactions. Global synchrony was the same in racially concordant interactions regardless of who was leading, but greater global synchrony occurred in racially discordant interactions when the patient was leading (p < .05). Conclusions: This is the first study to use a dynamic jointly determined measure of behavior to assess oncology interactions. Contrary to our hypothesis, nonverbal synchrony was greater in racially discordant interactions than in racially concordant interactions. Patients are driving more of the synchrony in racially discordant interactions. This may suggest that patients in racially discordant interactions adapt to their physicians to bridge racial differences. Findings could contribute to physician training to enhance coordination and outcomes in oncology interactions.
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Hamel, Lauren M., Robert Moulder, Susan Eggly, Terrance Lynn Albrecht, Steven Boker, David W. Dougherty i Louis Penner. "Comparing nonverbal synchrony in racially concordant and racially discordant oncology interactions." Journal of Clinical Oncology 37, nr 15_suppl (20.05.2019): 11525. http://dx.doi.org/10.1200/jco.2019.37.15_suppl.11525.
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11525 Background: Communication in racially discordant (Black patient, non-Black physician) oncology interactions, which constitute about 80% of Black patients’ interactions, is generally poorer than in racially concordant interactions, and likely contributes to treatment disparities. However, the nonverbal behaviors that contribute to this problem are largely unknown. We examined nonverbal synchrony, or the nonconscious coordination of movement, which can reflect relationship quality. We hypothesized that racially discordant interactions will have lower levels of nonverbal synchrony. Methods: Data include video recordings of 68 Black patients and 163 White patients discussing treatment with their non-Black oncologists. Recordings were submitted to motion detection software to measure nonverbal synchrony. This software measures global synchrony (all correlated motion), peak synchrony (all positively correlated motion), who is leading the interaction (similar to who is leading in ballroom dancing), and how much synchrony occurs based on who is leading the interaction. Using multi-level models, we investigated whether nonverbal synchrony differed in racially concordant and racially discordant dyads. Results: Findings showed greater levels of global synchrony (p < .05) and greater peak synchrony (p < .05) in racially discordant interactions compared to racially concordant interactions. Global synchrony was the same in racially concordant interactions regardless of who was leading, but greater global synchrony occurred in racially discordant interactions when the patient was leading (p < .05). Conclusions: This is the first study to use a dynamic jointly determined measure of behavior to assess oncology interactions. Contrary to our hypothesis, nonverbal synchrony was greater in racially discordant interactions than in racially concordant interactions. It appears patients are driving more of the synchrony in racially discordant interactions. This may suggest that patients in racially discordant interactions adapt to their physicians to bridge racial differences. Findings could contribute to physician training to enhance coordination and outcomes in oncology interactions.
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Post, Eric, Pernille Sporon Bøving, Christian Pedersen i Megan A. MacArthur. "Synchrony between caribou calving and plant phenology in depredated and non-depredated populations". Canadian Journal of Zoology 81, nr 10 (1.10.2003): 1709–14. http://dx.doi.org/10.1139/z03-172.
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Two main hypotheses have been proposed to explain reproductive synchrony exhibited by many species of large herbivores: the predation hypothesis and the seasonality hypothesis. Although examples supporting both hypotheses have been presented, no study has compared the intraseasonal progression of parturition and plant phenology in depredated and non-depredated populations of large herbivores. We monitored, on a daily or near-daily basis, the progression of the caribou (Rangifer tarandus) calving seasons in two populations: the Caribou River population in Alaska, U.S.A., where predators of caribou are present and the Kangerlussuaq-Sisimiut population in West Greenland where such predators have been absent for approximately 4000 years. Simultaneously, we quantified directly the phenological progression of caribou forage plants on spatially replicated plots in both study sites. Parturition was significantly more synchronous in the West Greenland (predator-free) population than in the Alaskan (depredated) population. Progression of the calving seasons in both populations was highly synchronized to the progression of forage plant phenology, and the slopes of these relationships were statistically indistinguishable, with 50% of births having occurred when approximately 60%70% of forage plant species were emergent. These results document clear synchronization of the timing of parturition by caribou to plant phenology, regardless of predation pressure.
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Jones, Dylan M. "Disruption of Memory for Lip-Read Lists by Irrelevant Speech: Further Support for the Changing State Hypothesis". Quarterly Journal of Experimental Psychology Section A 47, nr 1 (luty 1994): 143–60. http://dx.doi.org/10.1080/14640749408401147.
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Two experiments critically re-examine the finding of Campbell and Dodd (1984, Experiment 2), which suggests that irrelevant speech disrupts the encoding of visual material for serial recall. Support is sought for the competing view that the effect of irrelevant speech is on storage by comparing the effect of a range of acoustic conditions on memory for graphic and lip-read lists. Initially, serial short-term recall of visually presented lists was examined with irrelevant speech that was both asynchronous with the visually presented items and of varied speech content (Experiment 1a). In this experiment substantial impairments in recall of both graphic and lip-read lists were found. However, with unvarying asynchronous speech (Experiment 1b) the effect of speech was small and non-significant. Experiment 2 examined the effect of changing state and of synchrony of speech with lip movements. When conditions of synchronous and asynchronous unvarying speech were contrasted, no significant effect of synchrony or irrelevant speech was found (Experiment 2a and 2c). In contrast, when the speech was varying in content, a strong effect of irrelevant speech was found; moreover, the effect was roughly the same for synchronous and asynchronous materials (Experiment 2b). The contrast in outcome with varying and unvarying speech provides strong support for the “changing state” model of the irrelevant speech effect. Coupled with the absence of an effect of synchrony in Experiment 2, these experiments reinforce the view that disruption by irrelevant speech occurs in memory, not at encoding.
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Lindsey, B. G., K. F. Morris, R. Shannon i G. L. Gerstein. "Repeated Patterns of Distributed Synchrony in Neuronal Assemblies". Journal of Neurophysiology 78, nr 3 (1.09.1997): 1714–19. http://dx.doi.org/10.1152/jn.1997.78.3.1714.
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Lindsey, B. G., K. F. Morris, R. Shannon, and G. L. Gerstein. Repeated patterns of distributed synchrony in neuronal assemblies. J. Neurophysiol. 78: 1714–1719, 1997. Models of brain function predict that the recurrence of a process or state will be reflected in repeated patterns of correlated activity. Previous work on medullary raphe assembly dynamics revealed transient changes inimpulse synchrony. This study tested the hypothesis that these variations in synchrony include distributed nonrandom patterns of association. Spike trains were recorded simultaneously in the ventrolateral medulla, n. raphe obscurus, and n. raphe magnus of four anesthetized (Dial), vagotomized, paralyzed, and artificially ventilated adult cats. The “gravitational” representation of spike trains was used to detect moments of impulse synchrony in neuronal assemblies visualized as variations in the aggregation velocities of particles corresponding to each neuron. Template matching algorithms were developed to identify excessively repeating patterns of particle condensation rates. Repeating patterns weredetected in each animal. The reiterated patterns represented anemergent property not apparent in either corresponding firing rate histograms or conventional gravity representations. Overlapping subsets of neurons represented in different patterns were unmasked when the template resolution was changed. The results demonstrate repeated transient network configurations defined by the tightness and duration of synchrony in different combinations of neurons and suggest that multiple information streams are conveyed concurrently by fluctuations in the synchrony of on-going activity.
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Pratt, Maayan, Magi Singer, Yaniv Kanat-Maymon i Ruth Feldman. "Infant negative reactivity defines the effects of parent–child synchrony on physiological and behavioral regulation of social stress". Development and Psychopathology 27, nr 4pt1 (6.10.2015): 1191–204. http://dx.doi.org/10.1017/s0954579415000760.
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AbstractHow infants shape their own development has puzzled developmentalists for decades. Recent models suggest that infant dispositions, particularly negative reactivity and regulation, affect outcome by determining the extent of parental effects. Here, we used a microanalytic experimental approach and proposed that infants with varying levels of negative reactivity will be differentially impacted by parent–infant synchrony in predicting physiological and behavioral regulation of increasing social stress during an experimental paradigm. One hundred and twenty-two mother–infant dyads (4–6 months) were observed in the face-to-face still face (SF) paradigm and randomly assigned to three experimental conditions: SF with touch, standard SF, and SF with arms’ restraint. Mother–infant synchrony and infant negative reactivity were observed at baseline, and three mechanisms of behavior regulation were microcoded; distress, disengagement, and social regulation. Respiratory sinus arrhythmia baseline, reactivity, and recovery were quantified. Structural equation modeling provided support for our hypothesis. For physiological regulation, infants high in negative reactivity receiving high mother–infant synchrony showed greater vagal withdrawal, which in turn predicted comparable levels of vagal recovery to that of nonreactive infants. In behavioral regulation, only infants low in negative reactivity who received high synchrony were able to regulate stress by employing social engagement cues during the SF phase. Distress was reduced only among calm infants to highly synchronous mothers, and disengagement was lowest among highly reactive infants experiencing high mother–infant synchrony. Findings chart two pathways by which synchrony may bolster regulation in infants of high and low reactivity. Among low reactive infants, synchrony builds a social repertoire for handling interpersonal stress, whereas in highly reactive infants, it constructs a platform for repeated reparation of momentary interactive “failures” and reduces the natural tendency of stressed infants to disengage from source of distress. Implications for the construction of synchrony-focused interventions targeting infants of varying dispositions are discussed.
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Grant, Valerie J., i Lawrence W. Chamley. "Can mammalian mothers influence the sex of their offspring peri-conceptually?" REPRODUCTION 140, nr 3 (wrzesień 2010): 425–33. http://dx.doi.org/10.1530/rep-10-0137.
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Although controversial, growing evidence from evolutionary biology suggests that the mammalian mother may have a role in influencing the sex of her offspring. However, there is competing information on the molecular mechanisms by which such influence could be manifested. The new initiatives are based on hypotheses from evolutionary biology: the ‘good condition’ hypothesis, which suggests that post conception, higher levels of maternal glucose may differentially promote the development of male embryos; and the ‘maternal dominance’ hypothesis, which proposes that before conception, higher follicular testosterone may influence the development of the ovum so that it emerges already adapted to receive an X- or a Y-chromosome-bearing spermatozoon. Now, it seems these hypothesised mechanisms could be operating in synchrony, each complementing and reinforcing the other. On the other hand, there are continuing problems in identifying a precise sequence of mechanisms as evidenced from research in sperm-sorting. Research on high-fat diets and the sex ratio in polytocous species may indicate important differences in proximate mechanisms for sex allocation between polytocous and monotocous mammals.
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Berger, Joel. "Facilitation of Reproductive Synchrony by Gestation Adjustment in Gregarious Mammals: A New Hypothesis". Ecology 73, nr 1 (luty 1992): 323–29. http://dx.doi.org/10.2307/1938743.
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Lotto, Andrew J., i Keith R. Kluender. "Synchrony capture hypothesis fails to account for effects of amplitude on voicing perception". Journal of the Acoustical Society of America 111, nr 2 (luty 2002): 1056–62. http://dx.doi.org/10.1121/1.1433809.
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Preisig, Basil C., Lars Riecke, Matthias J. Sjerps, Anne Kösem, Benjamin R. Kop, Bob Bramson, Peter Hagoort i Alexis Hervais-Adelman. "Selective modulation of interhemispheric connectivity by transcranial alternating current stimulation influences binaural integration". Proceedings of the National Academy of Sciences 118, nr 7 (10.02.2021): e2015488118. http://dx.doi.org/10.1073/pnas.2015488118.
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Brain connectivity plays a major role in the encoding, transfer, and integration of sensory information. Interregional synchronization of neural oscillations in the γ-frequency band has been suggested as a key mechanism underlying perceptual integration. In a recent study, we found evidence for this hypothesis showing that the modulation of interhemispheric oscillatory synchrony by means of bihemispheric high-density transcranial alternating current stimulation (HD-TACS) affects binaural integration of dichotic acoustic features. Here, we aimed to establish a direct link between oscillatory synchrony, effective brain connectivity, and binaural integration. We experimentally manipulated oscillatory synchrony (using bihemispheric γ-TACS with different interhemispheric phase lags) and assessed the effect on effective brain connectivity and binaural integration (as measured with functional MRI and a dichotic listening task, respectively). We found that TACS reduced intrahemispheric connectivity within the auditory cortices and antiphase (interhemispheric phase lag 180°) TACS modulated connectivity between the two auditory cortices. Importantly, the changes in intra- and interhemispheric connectivity induced by TACS were correlated with changes in perceptual integration. Our results indicate that γ-band synchronization between the two auditory cortices plays a functional role in binaural integration, supporting the proposed role of interregional oscillatory synchrony in perceptual integration.
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Cram, Dominic L., Arne Jungwirth, Helen Spence-Jones i Tim Clutton-Brock. "Reproductive conflict resolution in cooperative breeders". Behavioral Ecology 30, nr 6 (29.08.2019): 1743–50. http://dx.doi.org/10.1093/beheco/arz143.
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Abstract Female infanticide is common in animal societies where groups comprise multiple co-breeding females. To reduce the risk that their offspring are killed, mothers can synchronize breeding and pool offspring, making it hard for females to avoid killing their own young. However, female reproductive conflict does not invariably result in reproductive synchrony, and we lack a general hypothesis explaining the variation in conflict resolution strategies seen across species. Here, we investigate the fitness consequences of birth timing relative to other females and the prevalence of birth synchrony in cooperatively breeding Kalahari meerkats (Suricata suricatta). We show that, although there would be substantial benefits to females in synchronizing births and reducing their risk of infanticide, birth synchrony is rare. Since precise breeding synchrony has evolved in a related species with similar infanticidal female reproductive conflict, its absence in meerkats requires an evolutionary explanation. We therefore explore the costs and benefits of synchronizing breeding in two theoretical models, each of which contrasts synchrony with an alternative reproductive strategy: (i) breeding opportunistically and accepting fitness losses to infanticide or (ii) suppressing the reproduction of others to prevent infanticide. Our models show that the costs of synchrony constrain its development if subordinates breed infrequently, and that selection instead favors the suppression of subordinate reproduction by the dominant and opportunistic reproduction by subordinates. Together, our results suggest that the resolution of reproductive conflict in animal societies is shaped by differential breeding propensities among female group members, leading to divergent conflict resolution strategies even in closely related species.
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Vidal, Juan R., Maximilien Chaumon, J. Kevin O'Regan i Catherine Tallon-Baudry. "Visual Grouping and the Focusing of Attention Induce Gamma-band Oscillations at Different Frequencies in Human Magnetoencephalogram Signals". Journal of Cognitive Neuroscience 18, nr 11 (listopad 2006): 1850–62. http://dx.doi.org/10.1162/jocn.2006.18.11.1850.
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Neural oscillatory synchrony could implement grouping processes, act as an attentional filter, or foster the storage of information in short-term memory. Do these findings indicate that oscillatory synchrony is an unspecific epiphenomenon occurring in any demanding task, or that oscillatory synchrony is a fundamental mechanism involved whenever neural cooperation is requested? If the latter hypothesis is true, then oscillatory synchrony should be specific, with distinct visual processes eliciting different types of oscillations. We recorded magnetoencephalogram (MEG) signals while manipulating the grouping properties of a visual display on the one hand, and the focusing of attention to memorize part of this display on the other hand. Grouping-related gamma oscillations were present in all conditions but modulated by the grouping properties of the stimulus (one or two groups) in the high gamma-band (70–120 Hz) at central occipital locations. Attention-related gamma oscillations appeared as an additional component whenever attentional focusing was requested in the low gamma-band (44–66 Hz) at parietal locations. Our results thus reveal the existence of a functional specialization in the gamma range, with grouping-related oscillations showing up at higher frequencies than attention-related oscillations. The pattern of oscillatory synchrony is thus specific of the visual process it is associated with. Our results further suggest that both grouping processes and focused attention rely on a common implementation process, namely, gamma-band oscillatory synchrony, a finding that could account for the fact that coherent percepts are more likely to catch attention than incoherent ones.
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Hickey, Paige, Annie Barnett-Young, Aniruddh D. Patel i Elizabeth Race. "Environmental rhythms orchestrate neural activity at multiple stages of processing during memory encoding: Evidence from event-related potentials". PLOS ONE 15, nr 11 (18.11.2020): e0234668. http://dx.doi.org/10.1371/journal.pone.0234668.
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Accumulating evidence suggests that rhythmic temporal structures in the environment influence memory formation. For example, stimuli that appear in synchrony with the beat of background, environmental rhythms are better remembered than stimuli that appear out-of-synchrony with the beat. This rhythmic modulation of memory has been linked to entrained neural oscillations which are proposed to act as a mechanism of selective attention that prioritize processing of events that coincide with the beat. However, it is currently unclear whether rhythm influences memory formation by influencing early (sensory) or late (post-perceptual) processing of stimuli. The current study used stimulus-locked event-related potentials (ERPs) to investigate the locus of stimulus processing at which rhythm temporal cues operate in the service of memory formation. Participants viewed a series of visual objects that either appeared in-synchrony or out-of-synchrony with the beat of background music and made a semantic classification (living/non-living) for each object. Participants’ memory for the objects was then tested (in silence). The timing of stimulus presentation during encoding (in-synchrony or out-of-synchrony with the background beat) influenced later ERPs associated with post-perceptual selection and orienting attention in time rather than earlier ERPs associated with sensory processing. The magnitude of post-perceptual ERPs also differed according to whether or not participants demonstrated a mnemonic benefit for in-synchrony compared to out-of-synchrony stimuli, and was related to the magnitude of the rhythmic modulation of memory performance across participants. These results support two prominent theories in the field, the Dynamic Attending Theory and the Oscillation Selection Hypothesis, which propose that neural responses to rhythm act as a core mechanism of selective attention that optimize processing at specific moments in time. Furthermore, they reveal that in addition to acting as a mechanism of early attentional selection, rhythm influences later, post-perceptual cognitive processes as events are transformed into memory.
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Numata, Shinya, Naoki Kachi, Toshinori Okuda i N. Manokaran. "Chemical defences of fruits and mast-fruiting of dipterocarps". Journal of Tropical Ecology 15, nr 5 (wrzesień 1999): 695–700. http://dx.doi.org/10.1017/s026646749900111x.
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Mast-fruiting is the intermittent and synchronous production of large fruits by a population of plants at long intervals (Herrera et al. 1998, Kelly 1994). Several hypotheses have been proposed concerning the adaptive advantages of mast-fruiting (Janzen 1971, 1974; Kelly 1994), and some field observations have provided evidence for these hypotheses (Norton & Kelly 1988, Shibata et al. 1998, Sork 1993). The predator-satiation hypothesis is one well-known explanation for reproductive synchrony in plants and animals (Janzen 1971, 1974; Kelly 1994). This hypothesis claims that mast fruiting at irregular intervals of several years is an effective means of satiating vertebrate fruit predators: low seed production can only support low densities of predators during the periods between mast-fruiting events, but more fruits are produced than predators can consume in masting years (Janzen 1971, Kelly 1994). Thus, it may be said that mast-fruiting is a defence strategy of plants against post-dispersal vertebrate fruit predators.
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Liu, Peter Y., Steven M. Pincus, Daniel M. Keenan, Ferdinand Roelfsema i Johannes D. Veldhuis. "Joint synchrony of reciprocal hormonal signaling in human paradigms of both ACTH excess and cortisol depletion". American Journal of Physiology-Endocrinology and Metabolism 289, nr 1 (lipiec 2005): E160—E165. http://dx.doi.org/10.1152/ajpendo.00007.2005.
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The hypothalamo-pituitary-adrenal axis is a stress-adaptive neuroendocrine ensemble, in which adrenocorticotropin (ACTH) drives cortisol secretion (feedforward) and cortisol restrains ACTH outflow (feedback). Quantifying direction- and pathway-specific adjustments within this and other interlinked systems by noninvasive means remains difficult. The present study tests the hypothesis that forward and reverse cross-approximate entropy (X-ApEn), a lag-, scale-, and model-independent measure of two-signal synchrony, would allow quantifiable discrimination of feedforward (ACTH → cortisol) and feedback (cortisol → ACTH) control. To this end, forward X-ApEn was defined by employing serial ACTH concentrations as a template to appraise pair-wise synchrony with cortisol secretion rates and vice versa for reverse X-ApEn. Coupled hormone profiles included normal ACTH-normal cortisol, high ACTH-high cortisol, and high ACTH-low cortisol concentrations in 35 healthy subjects, 21 patients with tumoral ACTH secretion, and 9 volunteers given placebo and a steroidogenic inhibitor, respectively. We used forward and reverse X-ApEn analyses to identify marked and equivalent losses of feedforward and feedback linkages (both P < 0.001) in patients with tumoral ACTH secretion. An identical analytical strategy revealed that ACTH → cortisol feedforward synchrony decreases ( P < 0.001), whereas cortisol → ACTH feedback synchrony increases ( P < 0.001), in response to hypocortisolemia. The collective outcomes establish precedence for pathway-specific adaptations in a major neurohormonal system. Thus quantification of directionally defined joint synchrony of biologically coupled signals offers a noninvasive strategy to dissect feedforward- and feedback-selective adaptations in an interactive axis.
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Bogdziewicz, Michał, Marcos Fernández-Martínez, Raul Bonal, Jordina Belmonte i Josep Maria Espelta. "The Moran effect and environmental vetoes: phenological synchrony and drought drive seed production in a Mediterranean oak". Proceedings of the Royal Society B: Biological Sciences 284, nr 1866 (listopad 2017): 20171784. http://dx.doi.org/10.1098/rspb.2017.1784.
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Masting is the highly variable production of synchronized seed crops, and is a common reproductive strategy in plants. Weather has long been recognized as centrally involved in driving seed production in masting plants. However, the theory behind mechanisms connecting weather and seeding variation has only recently been developed, and still lacks empirical evaluation. We used 12-year long seed production data for 255 holm oaks ( Quercus ilex ), as well as airborne pollen and meteorological data, and tested whether masting is driven by environmental constraints: phenological synchrony and associated pollination efficiency, and drought-related acorn abscission. We found that warm springs resulted in short pollen seasons, and length of the pollen seasons was negatively related to acorn production, supporting the phenological synchrony hypothesis. Furthermore, the relationship between phenological synchrony and acorn production was modulated by spring drought, and effects of environmental vetoes on seed production were dependent on last year's environmental constraint, implying passive resource storage. Both vetoes affected among-tree synchrony in seed production. Finally, precipitation preceding acorn maturation was positively related to seed production, mitigating apparent resource depletion following high crop production in the previous year. These results provide new insights into mechanisms beyond widely reported weather and seed production correlations.
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Descamps, Sébastien. "Breeding synchrony and predator specialization: A test of the predator swamping hypothesis in seabirds". Ecology and Evolution 9, nr 3 (15.01.2019): 1431–36. http://dx.doi.org/10.1002/ece3.4863.
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Maier, Julie AK, i Robert G. White. "Timing and synchrony of activity in caribou". Canadian Journal of Zoology 76, nr 11 (1.11.1998): 1999–2009. http://dx.doi.org/10.1139/z98-137.
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Activity data were analyzed to assess activity patterns of caribou (Rangifer tarandus granti). We hypothesized that equal day and night activity, termed nychthemeral activity, would be expected if food constitutes a limiting resource for a highly gregarious species. To test this hypothesis, we investigated activity patterns of two caribou populations at the same latitude: one captive with no food limitation and the other wild and free-ranging in the Alaska Range in interior Alaska known to be at the end of a 3-year low plane of nutrition. For captive caribou, activity patterns were determined from focal-animal behavioural observations each month except May. Data were collected on wild caribou using activity-recording radio collars in each of three seasons: late winter, postcalving, and midsummer. Wild and captive caribou exhibited nychthemeral activity and did not time activity to sunrise or sunset. Wild caribou exhibited no among-group synchrony. Within-group synchrony was high in both herds. Wild caribou exhibited significantly fewer cycles of activity than captive caribou. Longer resting bouts in late winter, and longer active bouts postcalving and in midsummer for wild caribou, were interpreted as behavioural responses to ecological effects of limited food availability, with and without snow, and disturbance by insects.
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Lang, Eric J. "GABAergic and Glutamatergic Modulation of Spontaneous and Motor-Cortex-Evoked Complex Spike Activity". Journal of Neurophysiology 87, nr 4 (1.04.2002): 1993–2008. http://dx.doi.org/10.1152/jn.00477.2001.
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Olivocerebellar activity is organized such that synchronous complex spikes occur primarily among Purkinje cells located within the same parasagittally oriented strip of cortex. Previous findings have shown that this synchrony distribution is modulated by the release of GABA and glutamate within the inferior olive, which probably act by controlling the efficacy of the electrotonic coupling between olivary neurons. The relative strengths of these two neurotransmitters in modulating the patterns of synchrony were compared by obtaining multiple electrode recordings of spontaneous crus 2a complex spike activity during intraolivary injection of solutions containing a GABAA (picrotoxin) and/or AMPA [1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide disodium (NBQX)] receptor antagonist. Injection of either antagonist led to increased synchrony between cells located within the same parasagittally oriented ≈250-μm-wide cortical strip. Picrotoxin also increased complex spike synchrony among cells located in different cortical strips, leading to a less prominent banding pattern, whereas injections of NBQX tended to decrease complex spike synchrony among such cells, enhancing the banding pattern. The relative strength of these two classes of olivary afferents was assessed by first injecting one of the antagonists alone and then in combination with the other. The enhanced banding pattern of complex spike synchrony following injection of NBQX alone remained during the subsequent combined injection of both antagonists. Furthermore, the widespread synchronization of complex spike activity following injection of picrotoxin alone was partially or completely reversed by combined injection of picrotoxin and NBQX. Changes in the climbing fiber reflex induced by the intraolivary injections paralleled the changes observed for spontaneous complex spike activity, indicating that the effects of picrotoxin and NBQX on the synchrony distribution reflect changes in the pattern of effective coupling of inferior olivary neurons and demonstrating that synchronous complex spike activity does not require simultaneous excitatory input to olivary cells. Finally the pattern of synchrony during motor cortical stimulation was examined. It was found that the patterns of synchrony for motor-cortex-evoked complex spike activity were similar to those of spontaneous activity, indicating an important role for electrotonic coupling in determining the response of the olivocerebellar system to afferent input. Moreover, intraolivary injections of picrotoxin increased the spatial distribution of the evoked response. In sum, the results provide evidence for the hypothesis that electrotonic coupling of inferior olivary neurons via gap junctions is the mechanism underlying complex spike synchrony and that this coupling plays an important role in determining the responses of the olivocerebellar system to synaptic input.
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Wang, Xin, Daniel M. Keenan, Steven M. Pincus, Peter Y. Liu i Johannes D. Veldhuis. "Oscillations in joint synchrony of reproductive hormones in healthy men". American Journal of Physiology-Endocrinology and Metabolism 301, nr 6 (grudzień 2011): E1163—E1173. http://dx.doi.org/10.1152/ajpendo.00138.2011.
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Negative-feedback (inhibitory) and positive-feedforward (stimulatory) processes regulate physiological systems. Whether such processes are themselves rhythmic is not known. Here, we apply cross-approximate entropy (cross-ApEn), a noninvasive measurement of joint (pairwise) signal synchrony, to inferentially assess hypothesized circadian and ultradian variations in feedback coupling. The data comprised simultaneous measurements of three pituitary and one peripheral hormone (LH, FSH, prolactin, and testosterone) in 12 healthy men each sampled every 10 min for 4 days (5,760 min). Ergodicity, due to the time series stationarity of the measurements over the 4 days, allows for effective estimation of parameters based upon the 12 subjects. Cross-ApEn changes were quantified via moving-window estimates applied to 4-day time series pairs. The resultant ordered windowed cross-ApEn series (in time) were subjected to power spectrum analysis. Rhythmicity was assessed against the null hypothesis of randomness using 1,000 simulated periodograms derived by shuffling the interpulse-interval hormone-concentration segments and redoing cross-ApEn windows and spectral analysis. By forward cross-ApEn analysis, paired LH-testosterone, LH-prolactin, and LH-FSH synchrony maintained dominant rhythms with periodicities of 18–22.5, 18, and 22.5 h, respectively (each P < 0.001). By reverse (feedback) cross-ApEn analysis, testosterone-LH, testosterone-prolactin, and testosterone-FSH synchrony cycles were 30, 18, and 30–45 h, respectively (each P ≤ 0.001). Significant 8- or 24-h rhythms were also detected in most linkages, and maximal bihormonal synchrony occurred consistently at ∼0400–0500. Collectively, these analyses demonstrate significant ultradian (<24 h), circadian (∼24 h), and infradian (>24 h) oscillations in pituitary-testis synchrony, wherein maximal biglandular coordination is strongly constrained to the early morning hours.
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Harrison, Matthew T. "Accelerated Spike Resampling for Accurate Multiple Testing Controls". Neural Computation 25, nr 2 (luty 2013): 418–49. http://dx.doi.org/10.1162/neco_a_00399.
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Controlling for multiple hypothesis tests using standard spike resampling techniques often requires prohibitive amounts of computation. Importance sampling techniques can be used to accelerate the computation. The general theory is presented, along with specific examples for testing differences across conditions using permutation tests and for testing pairwise synchrony and precise lagged-correlation between many simultaneously recorded spike trains using interval jitter.
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Bouwmeester, Jessica, i Michael L. Berumen. "High reproductive synchrony of Acropora (Anthozoa: Scleractinia) in the Gulf of Aqaba, Red Sea". F1000Research 4 (5.01.2015): 2. http://dx.doi.org/10.12688/f1000research.6004.1.
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Coral spawning in the northern Gulf of Aqaba has been reported to be asynchronous, making it almost unique when compared to other regions in the world. Here, we document the reproductive condition of Acropora corals in early June 2014 in Dahab, in the Gulf of Aqaba, 125 km south of previous studies conducted in Eilat, Israel. Seventy-eight percent of Acropora colonies from 14 species had mature eggs, indicating that most colonies will spawn on or around the June full moon, with a very high probability of multi-species synchronous spawning. Given the proximity to Eilat, we predict that a comparable sampling protocol would detect similar levels of reproductive synchrony throughout the Gulf of Aqaba consistent with the hypothesis that high levels of spawning synchrony are a feature of all speciose coral assemblages.
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Wallis, Guy. "A spatial explanation for synchrony biases in perceptual grouping: Consequences for the temporal-binding hypothesis". Perception & Psychophysics 67, nr 2 (luty 2005): 345–53. http://dx.doi.org/10.3758/bf03206497.
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Barnea, Oren, Amit Huppert, Guy Katriel i Lewi Stone. "Spatio-Temporal Synchrony of Influenza in Cities across Israel: The “Israel Is One City” Hypothesis". PLoS ONE 9, nr 3 (12.03.2014): e91909. http://dx.doi.org/10.1371/journal.pone.0091909.
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Wan, Kirsty Y., i Raymond E. Goldstein. "Coordinated beating of algal flagella is mediated by basal coupling". Proceedings of the National Academy of Sciences 113, nr 20 (2.05.2016): E2784—E2793. http://dx.doi.org/10.1073/pnas.1518527113.
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Cilia and flagella often exhibit synchronized behavior; this includes phase locking, as seen inChlamydomonas, and metachronal wave formation in the respiratory cilia of higher organisms. Since the observations by Gray and Rothschild of phase synchrony of nearby swimming spermatozoa, it has been a working hypothesis that synchrony arises from hydrodynamic interactions between beating filaments. Recent work on the dynamics of physically separated pairs of flagella isolated from the multicellular algaVolvoxhas shown that hydrodynamic coupling alone is sufficient to produce synchrony. However, the situation is more complex in unicellular organisms bearing few flagella. We show that flagella ofChlamydomonasmutants deficient in filamentary connections between basal bodies display markedly different synchronization from the wild type. We perform micromanipulation on configurations of flagella and conclude that a mechanism, internal to the cell, must provide an additional flagellar coupling. In naturally occurring species with 4, 8, or even 16 flagella, we find diverse symmetries of basal body positioning and of the flagellar apparatus that are coincident with specific gaits of flagellar actuation, suggesting that it is a competition between intracellular coupling and hydrodynamic interactions that ultimately determines the precise form of flagellar coordination in unicellular algae.
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De Zeeuw, C. I., S. K. E. Koekkoek, D. R. W. Wylie i J. I. Simpson. "Association Between Dendritic Lamellar Bodies and Complex Spike Synchrony in the Olivocerebellar System". Journal of Neurophysiology 77, nr 4 (1.04.1997): 1747–58. http://dx.doi.org/10.1152/jn.1997.77.4.1747.
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De Zeeuw, C. I., S.K.E. Koekkoek, D.R.W. Wylie, and J. I. Simpson. Association between dendritic lamellar bodies and complex spike synchrony in the olivocerebellar system. J. Neurophysiol. 77: 1747–1758, 1997. Dendritic lamellar bodies have been reported to be associated with dendrodendritic gap junctions. In the present study we investigated this association at both the morphological and electrophysiological level in the olivocerebellar system. Because cerebellar GABAergic terminals are apposed to olivary dendrites coupled by gap junctions, and because lesions of cerebellar nuclei influence the coupling between neurons in the inferior olive, we postulated that if lamellar bodies and gap junctions are related, then the densities of both structures will change together when the cerebellar input is removed. Lesions of the cerebellar nuclei in rats and rabbits resulted in a reduction of the density of lamellar bodies, the number of lamellae per lamellar body, and the density of gap junctions in the inferior olive, whereas the number of olivary neurons was not significantly reduced. The association between lamellar bodies and electrotonic coupling was evaluated electrophysiologically in alert rabbits by comparing the occurrence of complex spike synchrony in different Purkinje cell zones of the flocculus that receive their climbing fibers from olivary subnuclei with different densities of lamellar bodies. The complex spike synchrony of Purkinje cell pairs, that receive their climbing fibers from an olivary subnucleus with a high density of lamellar bodies, was significantly higher than that of Purkinje cells, that receive their climbing fibers from a subnucleus with a low density of lamellar bodies. To investigate whether the complex spike synchrony is related to a possible synchrony between simple spikes, we recorded simultaneously the complex spike and simple spike responses of Purkinje cell pairs during natural visual stimulation. Synchronous simple spike responses did occur, and this synchrony tended to increase as the synchrony between the complex spikes increased. This relation raises the possibility that synchronously activated climbing fibers evoke their effects in part via the simple spike response of Purkinje cells. The present results indicate that dendritic lamellar bodies and dendrodendritic gap junctions can be downregulated concomitantly, and that the density of lamellar bodies in different olivary subdivisions is correlated with the degree of synchrony of their climbing fiber activity. Therefore these data support the hypothesis that dendritic lamellar bodies can be associated with dendrodendritic gap junctions. Considering that the density of dedritic lamellar bodies in the inferior olive is higher than in any other area of the brain, this conclusion implies that electrotonic coupling is important for the function of the olivocerebellar system.
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Krebs, Charles J., Knut Kielland, John Bryant, Mark O’Donoghue, Frank Doyle, Carol McIntyre, Donna DiFolco i in. "Synchrony in the snowshoe hare (Lepus americanus) cycle in northwestern North America, 1970–2012". Canadian Journal of Zoology 91, nr 8 (sierpień 2013): 562–72. http://dx.doi.org/10.1139/cjz-2013-0012.
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Snowshoe hares (Lepus americanus Erxleben, 1777) fluctuate in 9–10 year cycles throughout much of their North American range. Regional synchrony has been assumed to be the rule for these cycles, so that hare populations in virtually all of northwestern North America have been assumed to be in phase. We gathered qualitative and quantitative data on hare numbers and fur returns of Canada lynx (Lynx canadensis Kerr, 1792) in the boreal forest regions of Alaska, Yukon, Northwest Territories, and northern British Columbia to describe synchrony in the time window of 1970–2012. Broad-scale synchrony in lynx fur returns was strong from 1970 to about 1995 but then seemed to break down in different parts of this region. Hare populations at 20 sites in Alaska, the Yukon, and Northwest Territories showed peak populations that lagged by 1–4 years during the 1990s and 2000s cycles. The simplest hypothesis to explain these patterns of asynchrony in hare cycles is the movement of predators from British Columbia north into the Yukon and then east into the Northwest Territories and west into Alaska. A traveling wave of these cycles is clearly seen in the lynx fur returns from western Canada and Alaska from 1970 to 2009. One consequence of a failure of synchrony is that hare predators like Canada lynx and Great-horned Owls (Bubo virginianus (Gmelin, 1788)) can move from one adjacent area to the next within this region and survive long enough to prolong low densities in hare populations that have declined earlier.
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McKinnon, L., M. Picotin, E. Bolduc, C. Juillet i J. Bêty. "Timing of breeding, peak food availability, and effects of mismatch on chick growth in birds nesting in the High Arctic". Canadian Journal of Zoology 90, nr 8 (sierpień 2012): 961–71. http://dx.doi.org/10.1139/z2012-064.
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In seasonal environments, breeding events must be synchronized with resource peaks to ensure production and growth of offspring. As changes in climate may affect trophic levels differentially, we hypothesized that a lack of synchrony between chick hatch and resource peaks could decrease growth rates in chicks of shorebirds nesting in the High Arctic. To test this hypothesis, we compared growth curves of chicks hatching in synchrony with peak periods of food abundance to those hatching outside of these peak periods. We also tested for changes in lay dates of shorebirds in the Canadian Arctic using recent and historical data. Mean daily temperatures during the laying period increased since the 1950s by up to 1.5 °C, and changes in lay dates were apparent for three shorebird species, yet differences in median lay dates between 1954 and 2005–2008 were only significant for White-rumped Sandpiper ( Calidris fuscicollis (Viellot, 1819)). During 2005–2008, there was only 1 year of relatively high synchrony between hatch and resource peaks. Asynchrony between hatch and peaks in Tipulidae biomass reduced growth rates in chicks of Baird’s Sandpiper (Calidris bairdii (Coues, 1861)). As anticipated changes in climate may decouple phenological events, the effects of asynchrony on growth rates of arctic-nesting birds warrant further investigation.
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Miranda, Terence T., i M. Kathleen Pichora-Fuller. "Temporally Jittered Speech Produces Performance Intensity, Phonetically Balanced Rollover in Young Normal-Hearing Listeners". Journal of the American Academy of Audiology 13, nr 01 (styczeń 2002): 050–58. http://dx.doi.org/10.1055/s-0040-1715947.
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This study investigates whether temporally jittered stimuli will produce performance-intensity, phonetically balanced (PI-PB) rollover in young adults with normal hearing. Although not yet explicitly stated in the literature, there is clinical and theoretical evidence to suggest that PI-PB rollover, such as that found in cases of acoustic neuroma, is caused by neural dyssynchrony in the auditory system. Sixteen participants were tested with intact and temporally jittered word lists in quiet at 40, 55, 65, and uncomfortable listening level −5 dB HL. The results show significant rollover in the jittered but not the intact conditions. The results are consistent with the existing evidence that suggests that neural PI-PB rollover is caused by decreased neural synchrony and support the claim that temporal jitter simulates neural dyssynchrony. Furthermore, these results are consistent with the hypothesis that synchrony coding plays an important role in the perception of high-level speech.
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Shain, Cory, i Judith Tonhauser. "The synchrony and diachrony of differential object marking in Paraguayan Guaraní". Language Variation and Change 22, nr 3 (październik 2010): 321–46. http://dx.doi.org/10.1017/s0954394510000153.
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AbstractThis paper explores the synchrony and diachrony of differential object marking in Paraguayan Guaraní on the basis of a quantitative study of a corpus of naturally occurring data of the modern language and an investigation of object marking in a 17th-century catechism. We show that both animacy and topicality, but not definiteness, affect whether a direct object is marked in modern Guaraní, a finding that has implications for cross-linguistic theories of differential object marking, not all of which recognize topicality as a factor. We also find no categorical constraints on differential object marking in Guaraní, contrary to Bossong (1985b). Our study of the 17th-century catechism provides further support for Bossong's (1985b, 2009) claim that Guaraní did not have differential object marking when it came into contact with Spanish. The paper concludes with a discussion of the hypothesis that differential object marking in Guaraní resulted from contact with Spanish.
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Gasperini, Lucia. "Diachrony and Synchrony of the Latin Ablative". Diachronica 16, nr 1 (6.08.1999): 37–66. http://dx.doi.org/10.1075/dia.16.1.04gas.
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SUMMARY The present work is concerned with certain aspects of the syncretistic history and synchronic function of the Latin ablative. After a review of the main results achieved and the questions still open in the comparative reconstruction of the Indo-European ablative, locative and instrumental cases, whose merger brought about the Latin ablative, the nature of the syncretism itself is investigated, by drawing some hints from the forms to shed light on the functions. In this treatment the thesis of Meiser (1992) concerning their syncretism through congruence of extensions gives rise, in fact, to interesting corollaries. The third and main part of the paper constitutes a reconstruction hypothesis of the Latin strategies to express the original instrumental meaning area through the alternate use of inherited bare cases and extensive prepositional phrases. The animacy hierarchy with its correlation of attributes seems a proper criterion through which Latin organizes the fluid and somehow redundant situation of a prepositional-case system by building a morphosyntactic schema. RÉSUMÉ Le present travail traite de quelques aspects de la genese syncretiste et du fonctionnement synchronique de l'ablatif latin. Apres un aperçu des principaux acquis et des questions toujours ouvertes en matiere de la reconstruction de l'ablatif, du locatif et de l'instrumental indo-europeens — dont la fusion aboutit a l'ablatif latin — , il est procede a l'examen d'un tel syncretisme, en relevant un certain nombre d'indices formels susceptibles de jeter la lumiere sur les fonctions. Dans ce developpement la these de Meiser (1992) sur le syncretisme a travers la correspondance d'extensions, donne lieu, en fait, a d'interessants corollaires. La troisieme — et principale — partie de 1'article consiste en une hypothese de reconstruction des strategies latines visant l'expression du domaine semantique de 1'instrumental, a travers l'alternance entre cas et groupes prepositionnels: la hierarchie de l'anime, avec sa correlation d'attributs, semble un critere adequat pour comprendre le façon dont le latin a organise la situation fluctuante et quelque peu redon-dante d'un systeme casuel/prepositionnel, en construisant un schema morpho-syntaxique. ZUSAMMENFASSUNG Die vorliegende Arbeit behandelt einige Aspekte der synkretistischen Genese sowie des synchronischen Funktionierens des lateinischen Ablativs. Zunachst werden in einem Uberblick die wichtigsten bereits erzielten Ergebnisse vorgestellt und dazu auch die immer noch ungelosten Fragen in der Rekonstruktion des indo-europaischen Ablativs, sowie des Lokativ- und Instrumentalkasus, deren Zusammenfall den lateinischen Ablativ hervor-gebracht hat. Anschliessend wird die Natur eines solchen Synkretismus erforscht, indem einige formale Hinweise im Hinblick auf eine Erklarung der Funktionen untersucht werden. In diesem Zusammenhang führt Meisers (1992) These iiber Synkretismus als ein Ergebnis der Kongruenz von Extensionen zu interessanten Schlußfolgerungen. Der dritte und wichtigste Teil des Beitrags betrifft den Versuch einer Rekonstruktion der lateinischen Strategien zur Gestaltung des ursprunglichen instrumentalen Bedeutungs-bereichs durch den wechselnden Gebrauch von bloBem Kasus und Prapositio-nalphrasen. Es stellt sich heraus, daB die Belebtheitshierarchie mit ihrer Korrelation der Attribute ein geeignetes Kriterium darstellt, mit dem das Lateinische die fließende und scheinbar redundante Situation eines praposi-tionalen Kasussystems durch die Entwicklung eines morphosyntaktischen Schemas behoben hat.
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Bartolomei, Fabrice, i Lionel Naccache. "The Global Workspace (GW) Theory of Consciousness and Epilepsy". Behavioural Neurology 24, nr 1 (2011): 67–74. http://dx.doi.org/10.1155/2011/127864.
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The global workspace (GW) theory proposes that conscious processing results from coherent neuronal activity between widely distributed brain regions, with fronto-parietal associative cortices as key elements. In this model, transition between conscious and non conscious states are predicted to be caused by abrupt non-linear massive changes of the level of coherence within this distributed neural space. Epileptic seizures offer a unique model to explore the validity of this central hypothesis. Seizures are often characterized by the occurrence of brutal alterations of consciousness (AOC) which are largely negatively impacting patients' lives. Recently, we have shown that these sudden AOC are contemporary to non-linear increases of neural synchrony within distant cortico-cortical and cortico-thalamic networks. We interpreted these results in the light of GW theory, and suggested that excessive synchrony could prevent this distributed network to reach the minimal level of differentiation and complexity necessary to the coding of conscious representations. These observations both confirm some predictions of the GW model, and further specify the physiological window of neural coherence (minimum and maximum) associated with conscious processing.
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Rogers, Tanya L., i Stephan B. Munch. "Hidden similarities in the dynamics of a weakly synchronous marine metapopulation". Proceedings of the National Academy of Sciences 117, nr 1 (23.12.2019): 479–85. http://dx.doi.org/10.1073/pnas.1910964117.
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Populations of many marine species are only weakly synchronous, despite coupling through larval dispersal and exposure to synchronous environmental drivers. Although this is often attributed to observation noise, factors including local environmental differences, spatially variable dynamics, and chaos might also reduce or eliminate metapopulation synchrony. To differentiate spatially variable dynamics from similar dynamics driven by spatially variable environments, we applied hierarchical delay embedding. A unique output of this approach, the “dynamic correlation,” quantifies similarity in intrinsic dynamics of populations, independently of whether their abundance is correlated through time. We applied these methods to 17 populations of blue crab (Callinectes sapidus) along the US Atlantic coast and found that their intrinsic dynamics were broadly similar despite largely independent fluctuations in abundance. The weight of evidence suggests that the latitudinal gradient in temperature, filtered through a unimodal response curve, is sufficient to decouple crab populations. As unimodal thermal performance is ubiquitous in ectotherms, we suggest that this may be a general explanation for the weak synchrony observed at large distances in many marine species, although additional studies are needed to test this hypothesis.
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Bregman, Micah R., John R. Iversen, David Lichman, Meredith Reinhart i Aniruddh D. Patel. "A method for testing synchronization to a musical beat in domestic horses (Equus ferus caballus)". Empirical Musicology Review 7, nr 3-4 (25.06.2013): 144. http://dx.doi.org/10.18061/emr.v7i3-4.3745.
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According to the “vocal learning and rhythmic synchronization hypothesis” (Patel, 2006), only species capable of complex vocal learning, such as humans and parrots, have the capacity to synchronize their movements to a musical beat. While empirical research to date on a few species (e.g., parrots and monkeys) has supported this hypothesis, many species remain to be examined. Domestic horses are particularly important to study, as they are vocal non-learners who are occasionally reported to move in synchrony with a musical beat, based on informal observations. If these reports are substantiated by scientific experiments, this would refute the vocal learning hypothesis and provide a new species for the comparative study of musical rhythm. Here we present a new method for testing whether horses can synchronize their trotting to a musical beat, including an illustration of data analysis based on data collected from one horse.
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Legett, Henry D., Ikkyu Aihara i X. E. Bernal. "The dual benefits of synchronized mating signals in a Japanese treefrog: attracting mates and manipulating predators". Philosophical Transactions of the Royal Society B: Biological Sciences 376, nr 1835 (23.08.2021): 20200340. http://dx.doi.org/10.1098/rstb.2020.0340.
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In dense mating aggregations, such as leks and choruses, acoustic signals produced by competing male conspecifics often overlap in time. When signals overlap at a fine temporal scale the ability of females to discriminate between individual signals is reduced. Yet, despite this cost, males of some species deliberately overlap their signals with those of conspecifics, synchronizing signal production in the chorus. Here, we investigate two hypotheses of synchronized mating signals in a Japanese treefrog ( Buergeria japonica ): (1) increased female attraction to the chorus (the beacon effect hypothesis) and (2) reduced attraction of eavesdropping predators (the eavesdropper avoidance hypothesis). Our results from playback experiments on female frogs and eavesdropping micropredators (midges and mosquitoes) support both hypotheses. Signal transmission and female phonotaxis experiments suggest that away from the chorus, synchronized calls are more attractive to females than unsynchronized calls. At the chorus, however, eavesdroppers are less attracted to calls that closely follow an initial call, while female attraction to individual signals is not affected. Therefore, synchronized signalling likely benefits male B. japonica by both increasing attraction of females to the chorus and reducing eavesdropper attacks. These findings highlight how multiple selective pressures likely promoted the evolution and maintenance of this behaviour. This article is part of the theme issue ‘Synchrony and rhythm interaction: from the brain to behavioural ecology’.
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Tranchant, Pauline, Marie-Élaine Lagrois, Antoine Bellemare, Benjamin G. Schultz i Isabelle Peretz. "Co-occurrence of Deficits in Beat Perception and Synchronization Supports Implication of Motor System in Beat Perception". Music & Science 4 (1.01.2021): 205920432199171. http://dx.doi.org/10.1177/2059204321991713.
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The main goal of this study was to test the hypothesis that disorders in entrainment to the beat of music originate from motor deficits. To this aim, we adapted the Beat Alignment Test and tested a large pool of control subjects, as well as nine individuals who had previously showed deficits in synchronization to the beat of music. The tasks consisted of tapping (Experiment 1) and bouncing (Experiment 2) in synchrony with the beat of non-classical music that varied in genre, tempo, and groove, and then judging whether a superimposed metronome was perceived as on or off the beat of the same selection of music. Results indicate concomitant deficits in both beat synchronization and the detection of misalignment with the beat, supporting the hypothesis that the motor system is implicated in beat perception.
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Kumar, D., P. D. Thompson i D. L. Wingate. "Absence of synchrony between human small intestinal migrating motor complex and rectal motor complex". American Journal of Physiology-Gastrointestinal and Liver Physiology 258, nr 1 (1.01.1990): G171—G172. http://dx.doi.org/10.1152/ajpgi.1990.258.1.g171.
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Both the human small intestine and rectum exhibit motor activity in which relatively brief bursts of powerful regular contractions recur with a similar periodicity. We used prolonged ambulant manometry to test the hypothesis that these activities are synchronous. Pressure activity from the duodenojejunum and the rectum was recorded continuously for 24 h in eight freely ambulant healthy adults. A total of 61 migrating motor complexes and 61 rectal motor complexes occurred in the group; the median periodicities of the two rhythms differed significantly (P = 0.025). There was no evidence of synchrony between the two biorhythms. We conclude that they are independent oscillations.
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Kidd, A. D., D. Francis i M. D. Bennett. "Replicon size, rate of DNA replication, and the cell cycle in a primary hexaploid triticale and its parents". Genome 35, nr 1 (1.02.1992): 126–32. http://dx.doi.org/10.1139/g92-021.
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It has been previously shown that, surprisingly, DNA synthesis in a hexaploid triticale resembled that in a hexaploid bread wheat much more than in a diploid rye cultivar with respect to (i) replicon size, (ii) rate of DNA replication fork movement, and (iii) the degree of synchrony of replicon activation. The wheat and rye cultivars were not the parents of the triticale, but it was suggested that perhaps in a triticale nucleus, DNA replication in chromosomes from rye may be governed to be similar to that of wheat chromosomes in the wheat parent. The present work aimed to test this hypothesis using DNA fibre autoradiography to study DNA replication in root meristem cells of a diploid rye, a tetraploid wheat, and the primary allohexaploid triticale derived from them. The results, which again showed striking differences between rye, wheat, and triticale, did not substantiate the above-mentioned hypothesis. Instead, factors in the hybrid triticale may interact to impose a new common replicon size, a new common rate of replication, and, a more synchronous pattern of activation of replication, all different from those found in either parent. These results provide evidence for the existence of an important genetic mechanism that can act to synchronize the developmental behaviour of different ancestral diploid genomes in allopolyploids. Variation in the expression of this mechanism may have important agronomic and evolutionary consequences. Perhaps improvement in nuclear stability and in kernal type achieved in triticale breeding involves selection for greater synchrony of replicon activation during DNA synthesis.Key words: cell cycle, DNA replication, replicon, S phase, triticale.
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Boulanger, Yan, i Dominique Arseneault. "Spruce budworm outbreaks in eastern Quebec over the last 450 years". Canadian Journal of Forest Research 34, nr 5 (1.05.2004): 1035–43. http://dx.doi.org/10.1139/x03-269.
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In this study we used dendrochronology to reconstruct the history of eastern spruce budworm (Choristoneura fumiferana (Clem.)) outbreaks over the last 450 years in the Bas-Saint-Laurent region of southeastern Quebec. In total, 260 tree cores were sampled from 204 beams in seven historic buildings and 12 trees in a virgin forest stand. Eight previously documented outbreaks (19751992, 19471958, 19141923, 18681882, 18321845, 18051812, 17521776, 17101724) and three presumed previous outbreaks (16781690, 16421648, 15771600) were identified based on periods of growth reduction. Of these 11 confirmed or presumed outbreaks, six were documented for the first time in eastern Quebec. Such data suggest that outbreak frequency has remained quite stable, with a mean interval of about 40 years between the midpoint of successive outbreaks since the mid-16th century. In addition, together with previous studies, our results indicate a strong spatial synchrony of spruce budworm outbreaks across central and eastern Quebec during the last 300 years. Consequently, our study does not support the hypothesis that spruce budworm outbreak frequency and synchrony increased during the 20th century.
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Valkeners, D., Y. Beckers, F. Piron i A. Théwis. "Effect of imbalance between energy and nitrogen supplies on microbial protein synthesis in growing double-muscled Belgian Blue bulls". Proceedings of the British Society of Animal Science 2003 (2003): 123. http://dx.doi.org/10.1017/s1752756200012825.
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Balancing the supply of nitrogen and energy-yielding substrates to rumen micro-organisms was proposed as a mechanism to maximise the capture of rumen degradable nitrogen (RDN) and to optimise microbial growth rate and efficiency. The objective of this study was to examine the effect of various time periods of imbalance between nitrogen and energy supplies for the rumen micro-organisms on the microbial protein synthesis (SPM) in growing double-muscled Belgian Blue bulls. This was realised by giving the same feedstuffs according to different meal patterns, which is one of the most robust test of the ‘synchrony’ hypothesis (Dewhurst et al., 2000).