63 resultados para Ecology, Evolution, Behavior and Systematics

em Deakin Research Online - Australia


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In the present study, wetting characteristics and evolution of microstructure of Sn–3.5Ag solder on Ag/Ni and Ni electroplated 304 stainless steel (304SS) substrates have been investigated. Solder alloy spread on Ag/Ni plated 304SS substrates exhibited better wetting as compared to Ni/304SS substrate. The formations of irregular shaped and coarser IMCs were found at the interface of solder/Ni/304SS substrate region whereas, solder/Ag/Ni/substrate interface showed continuous scallop and needle shaped IMCs. The precipitation of Ag3Sn, Ni–Sn, FeSn2 and lesser percentage of Fe–Cr–Sn IMCs were found at the interface of solder/Ag/Ni/substrate region whereas, solder/Ni/304 SS substrate exhibited predominantly FeSn2 and Fe–Cr–Sn IMCs. Presence of higher amount of Fe–Cr–Sn IMCs at the solder/Ni/304SS substrate interface inhibited the further wetting of solder alloy.

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The relative contribution of genetic and environmental factors in determining variation in life-history traits is of central interest to evolutionary biologists, but the physiological mechanisms underlying these traits are still poorly understood. Here we experimentally demonstrate opposing effects of nutritional stress on immune function, endocrine physiology, parental care, and reproduction between red and black head-color morphs of the Gouldian finch (Erythrura gouldiae). Although the body condition of black morphs was largely unaffected by diet manipulation, red birds were highly sensitive to dietary changes, exhibiting considerable within-individual changes in condition and immune function. Consequently, nutritionally stressed red birds delayed breeding, produced smaller broods, and reared fewer and lower-quality foster offspring than black morphs. Differences in offspring quality were largely due to morph-specific differences in parental effort: red morphs reduced parental provisioning, whereas black morphs adaptively elevated their provisioning effort to meet the increased nutritional demands of their foster brood. Nutritionally stressed genetic morphs also exhibited divergent glucocorticoid responses. Black morphs showed reduced corticosterone-binding globulin (CBG) concentrations and increased levels of free corticosterone, whereas red morphs exhibited reduced free corticosterone levels and elevated CBG concentrations. These opposing glucocorticoid responses highlight intrinsic differences in endocrine sensitivities and plasticity between genetic morphs, which may underlie the morph-specific differences in condition, behavior, and reproduction and thus ultimately contribute to the evolution and maintenance of color polymorphism.

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This article is part of a Special Issue SBN 2014. Photoperiod and the hormonal response it triggers are key determinants of reproductive timing in birds. However, other cues and physiological traits may permit flexibility in the timing of breeding and perhaps facilitate adaptation to global change. Opportunistic breeders are excellent models to study the adaptive significance of this flexibility, especially at the individual level. Here, we sought to quantify whether particular male physiological and behavioral traits were linked to reproductive timing and output in wild-derived zebra finches. We repeatedly assessed male stress-induced corticosterone levels (CORT), basal metabolic rate (BMR), and activity before releasing them into outdoor aviaries and quantifying each pair's breeding timing, investment, and output over a seven-month period. Despite unlimited access to food and water, the colony breeding activity occurred in waves, probably due to interpair social stimulations. Pairs adjusted their inter-clutch interval and clutch size to social and temperature cues, respectively, but only after successful breeding attempts, suggesting a facultative response to external cues. When these effects were controlled for statistically or experimentally, breeding intervals were repeatable within individuals across reproductive attempts. In addition, males' first laying date and total offspring production varied with complex interactions between pre-breeding CORT, BMR and activity levels. These results suggest that no one trait is under selection but that, instead, correlational selection acts on hormone levels, metabolism, and behavior. Together our results suggest that studying inter-individual variation in breeding strategy and their multiple physiological and behavioral underpinnings may greatly improve our understanding of the mechanisms underlying the evolution of breeding decisions.

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Two existing models are used to conceptualize the constrained and limited participation in the communist system. The mobilization model suggests that participation was so mobilized by the party/state that it was largely meaningless, while the disengagement model supports the idea that many communist citizens adopted non-participatory behaviors such as non-voting as a means of protest. This paper attempts to demonstrate the importance of a third model – the emergent democratic culture model. The survey results show that the participation index is in proportion to the number of elections in which a villager is involved; and a growing number of voters in Zhejiang are developing citizen-initiated participation, with rights consciousness.

This research finds that the level of participation is influenced by three major factors: the perceived worth of the election itself, regularity of electoral procedures, and the fairness of electoral procedures. It also finds that parochial political culture and political apathy still exist, and the emergent democratic consciousness falls short of an ideal democratic standard. While a highly democratic culture helps to develop village democracy, the apathetic attitude continues to support the authoritarian leadership and structure in many villages. The paper also gives an account of survey research in rural China and offers a thoughtful critique of the use of voting and non-voting as the sole indicator of political participation.

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The phase behavior, morphology and crystallization in blends of a low-molecular-weight (Mn = 1400) double-crystalline polyethylene-block-poly(ethylene oxide) (PE-PEO) diblock copolymer with poly(hydroxyether of bisphenol A) (PH) were investigated by differential scanning calorimetry, transmission electron microscopy and small-angle X-ray scattering. The symmetric PE-PEO diblock copolymer consists of a PH-miscible PEO block and a PH-immiscible PE block. However, PH only exhibits partial miscibility with the PEO block of the copolymer in the PH/PE-PEO blends; both macrophase and microphase separations took place. There existed two macrophases in the PH/PE-PEO blends, i.e., a PH-rich phase and a PE-PEO copolymer-rich phase. The PE block of the copolymer in the blends exhibited fractionated crystallization behavior by homogeneous nucleation. There appeared three crystallization exotherms related to the crystallization of the PE block within three different microenvironments in the PH/PE-PEO blends.

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Stress is thought to influence human eating behavior and has been examined in animal and human studies. Our understanding of the stress-eating relation is confounded by limitations inherent in the study designs; however, we can make some tentative conclusions that support the notion that stress can influence eating patterns in humans. Stress appears to alter overall food intake in two ways, resulting in under- or overeating, which may be influenced by stressor severity. Chronic life stress seems to be associated with a greater preference for energy- and nutrient-dense foods, namely those that are high in sugar and fat. Evidence from longitudinal studies suggests that chronic life stress may be causally linked to weight gain, with a greater effect seen in men. Stress-induced eating may be one factor contributing to the development of obesity. Future studies that measure biological markers of stress will assist our understanding of the physiologic mechanism underlying the stress-eating relation and how stress might be linked to neurotransmitters and hormones that control appetite.

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Reaction of the dimethylsilylmethyl-substituted tetraorganotin derivative CH2[CH2Sn(Ph2)CH2Si(H)Me2]2 (1) and CH2[CH2Sn(Ph2)CH2Si(i-PrO)Me2]2 (3), respectively, with mercuric chloride afforded the novel silicon- and tin-containing 10- and 20-membered rings cyclo-CH2[CH2Sn(Cl2)CH2Si(Me2)]2O (4) and cyclo-CH2[CH2Sn(Cl2)CH2Si(Me2)OSi(Me2)CH2Sn(Cl2)CH2]2CH2 (5). Both compounds 4 and 5 can be converted into the soluble Lewis acidic polymer poly-[Si(Me2)CH2Sn(Cl2)(CH2)3Sn(Cl2)CH2Si(Me2)O] (8). 119Sn NMR studies indicate that 4 acts as a bidentate Lewis acid toward chloride ions, exclusively forming the 1:1 complex [cyclo-CH2[CH2Sn(Cl2)CH2Si(Me2)]2O·Cl]-[(Ph3P)2N]+ (7). The molecular structures as determined by single-crystal X-ray diffraction analysis of 4 and 7 are reported.

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"Against a backdrop of advancing neoliberalism and globalisation, this timely book examines nine prominent Australians from diverse backgrounds - ʻglobal citizensʾ who have each enhanced public life through promoting universal values and human rights. The book charts over 50 years of campaigning, and espouses perennial causes such as peace, social justice, ecological sustainability and gender and racial equality. Ultimately, this inspiring volume sends a message of hope for Australian society and provides a benchmark for all proponents of change."--Publisher description.

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In the first section of this article, we discuss the metabolic responses to walking by describing the economy of walking during different locomotion velocities. Gender, weight status, and growth effects on metabolic responses to walking are reviewed. In the second section, we examine the use of technology to assess walking patterns and behavior in the community. We use an engineering approach for understanding how to measure objects that move, and these methods are used to assess walking used in transportation. In the third part of the paper, we summarize self-report methods that have been used to assess walking behavior and highlight the strengths and weaknesses of these methods. We illustrate how self-report methods are used to quantify walking behavior in the surveillance systems that are now widely used to ascertain walking prevalence and temporal changes in different populations. In the final section, we discuss ways of measuring the walkability of neighborhoods and the community to understand the influence of the built environment on walking behavior.