12 resultados para source-sink relationship

em Deakin Research Online - Australia


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In fragmented landscapes, a species' dispersal ability and response to habitat condition are key determinants of persistence. To understand the relative importance of dispersal and condition for survival of Nephrurus stellatus (Gekkonidae) in southern Australia, we surveyed 92 woodland remnants three times. This gecko favours early post-fire succession conditions so may be at risk of extinction in the long-unburnt agricultural landscape. Using N-mixture models, we compared the influence of four measures of isolation, patch area and two habitat variables on the abundance and occurrence of N. stellatus, while taking into account detection probability. Patch occupancy was high, despite the long-term absence of fire from most remnants. Distance to the nearest occupied site was the most informative measure of patch isolation, exhibiting a negative relationship with occupancy. Distance to a nearby conservation park had little influence, suggesting that mainland-island metapopulation dynamics are not important. Abundance and occurrence were positively related to %-cover of spinifex (Triodia), indicating that niche-related factors may also contribute to spatial dynamics. Patterns of patch occupancy imply that N. stellatus has a sequence of spatial dynamics across an isolation gradient, with patchy populations and source-sink dynamics when patches are within 300 m, metapopulations at intermediate isolation, and declining populations when patches are separated by >1-2 km. Considering the conservation needs of the community, habitat condition and connectivity may need to be improved before fire can be reintroduced to the landscape. We speculate that fire may interact with habitat degradation and isolation, increasing the risk of local extinctions.

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There are many large, easy-to-observe anseriform birds (ducks, geese, and swans) in northern Australia and New Guinea and they often gather in large numbers. Yet, the structure of their populations and their regional movements are poorly understood. Lack of understanding of population structure limits our capacity to understand source-sink dynamics relevant to their conservation or assess risks associated with avian-borne pathogens, in particular, avian influenza for which waterfowl are the main reservoir species. We set out to assess present-day genetic connectivity between populations of two widely distributed waterfowl in the Australo-Papuan tropics, magpie goose Anseranas semipalmata (Latham, 1798) and wandering whistling-duck Dendrocygna arcuata (Horsfield, 1824). Microsatellite data were obtained from 237 magpie geese and 64 wandering whistling-duck. Samples were collected across northern Australia, and at one site each in New Guinea and Timor Leste. In the wandering whistling-duck, genetic diversity was significantly apportioned by region and sampling location. For this species, the best model of population structure was New Guinea as the source population for all other populations. One remarkable result for this species was genetic separation of two flocks sampled contemporaneously on Cape York Peninsula only a few kilometers apart. In contrast, evidence for population structure was much weaker in the magpie goose, and Cape York as the source population provided the best fit to the observed structure. The fine scale genetic structure observed in wandering whistling-duck and magpie goose is consistent with earlier suggestions that the west-coast of Cape York Peninsula is a flyway for Australo-Papuan anseriforms between Australia and New Guinea across Torres Strait.

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In Western research, cruelty to animals in childhood has been associated with comorbid conduct problems and with interpersonal violence in later life. However, there is little understanding of the etiology of cruelty to animals, and what in the child's life may require attention if the chain linking animal cruelty and later violence is to be broken. The study reported in this paper investigated the association between parent-reported cruelty to animals, and parent- and self-reported psychological strengths and weaknesses in a sample of 379 elementary school children in an Eastern context, Malaysia. No gender differences were found in relation to cruelty to animals or psychological problems, as assessed with the Strengths and Difficulties Questionnaire (SDQ). However, there were different predictors of cruelty to animals for boys and girls. Regression analyses found that for boys, parent-reported hyperactivity was a unique predictor of Malicious and Total Cruelty to animals. For girls, self-reported conduct problems was a unique predictor of Typical Cruelty to animals. Parent-reported total difficulties were associated with Typical, Malicious, and Total Cruelty to animals. We suggest that routine screening of children with an instrument such as the SDQ may help to detect those children who may need to undergo further assessment and perhaps intervention to break the chain linking childhood cruelty to animals and later conduct problems.

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The research reported in this paper investigated the relationship between information usage and individual ticket-purchasing activity of Opera Australia customers in relation to specific Opera Australia products, namely, operetta and opera. The results provide some support for the notion that consumers of operetta and opera can be distinguished on the basis of their different behaviour in some areas. However, there is substantial “crossing-over” or inconsistency in the data. Longevity of association with the art-form, and purchasing tickets to both types of productions, tended to be related to increased reliance on information sources closer to Opera Australia.

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Purpose: An ongoing concern with the evaluation of auditory processing disorders is the extent that assessment instruments are influenced by higher order cognitive functions. This study examined the relationship between verbal working memory and performance on the Test for Auditory Processing Disorders in Children--Revised (SCAN-C; Keith, 2000b) in children with specific language impairment (SLI) and typically developing (TD) children.

Method: Sixteen children with SLI and 16 TD children ages 8/4 to 11 years participated in the study. The children were presented with the SCAN-C and tests measuring verbal working memory.

Results:
Initial comparisons revealed that the SLI group obtained significantly lower scores than the TD group on the SCAN-C. However, after controlling for verbal working memory, significant differences between the 2 groups were no longer observed. Correlational analyses revealed that the composite score from the SCAN-C was related to all tests assessing verbal working memory.

Conclusions:
Performance on the SCAN-C may be related to working memory functioning. As a consequence, it is unclear whether difficulty on this task should be viewed as a problem with auditory processing or a problem with verbal working memory.

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Objective: Family characteristics (relationship quality, parental behaviors, and attitudes relating to alcohol use) are known to influence alcohol use in the mid-teen years, and there is evidence that family characteristics have different influences on mid-teen girls versus boys. This study examined child gender differences in the association of family relationship quality, parental disapproval of children's alcohol use, and parental alcohol use with early adolescent alcohol use.

Method: Grade 6 and 8 students (modal age 11 and 13, respectively; N = 6,837; 52.6% female) were recruited from 231 schools across three Australian states. Hypotheses were tested using two-level ordinal logistic regression (individuals nested within schools). The main dependent measure was lifetime frequency of early adolescent alcohol consumption. Independent variables included mother's/father's alcohol use, closeness, conflict, and disapproval of adolescent alcohol use. Control variables included sensation seeking, peer alcohol use, and socioeconomic disadvantage.

Results: The key findings were that for the young age group (Grade 6), emotional closeness to the parent of the opposite sex was protective. Family conflict was associated with females' drinking in both age groups but not males' drinking.

Conclusions: There was evidence of gender differences in the epidemiology of family relationship quality and early alcohol use. Social developmental models may need revision to account for these child gender differences. Gender-specific family dynamics may be an important consideration for family-oriented prevention strategy.

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The basic differences between marketing managers and their technically trained counterpart managers [e.g., research and development (R&D), engineering, and manufacturing managers] in terms of work experience, training, and differing decision-making styles have often been suggested as a source of conflict, which acts as a barrier to effective working relationships and integration during new product development (NPD) work. In this paper, we empirically explore this issue by developing and testing a model of psychosocial differences (thought worlds and psychological distance) between the two groups of managers and their effect on communication, trust, and relationship effectiveness during NPD projects. We find that while thought world differences do still matter, it was from a marketing perspective that they had a stronger effect. These findings have implications for top management trying to manage the functional manager interface during NPD projects. We propose a semi-formalized approach to relationship building that may speed up the acquisition of social data that is often necessary to elevate working relationships to trusting ones and improve the efficiency of NPD work. Our model is tested using data from two samples, 184 technically trained managers and 145 marketing managers from Australian companies involved in NPD work.

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During the reproductive season, sea turtles use a restricted area in the vicinity of their nesting beaches, making them vulnerable to predation. At Raine Island (Australia), the highest density green turtle Chelonia mydas rookery in the world, tiger sharks Galeocerdo cuvier have been observed to feed on green turtles, and it has been suggested that they may specialise on such air-breathing prey. However there is little information with which to examine this hypothesis. We compared the spatial and temporal components of movement behaviour of these two potentially interacting species in order to provide insight into the predator-prey relationship. Specifically, we tested the hypothesis that tiger shark movements are more concentrated at Raine Island during the green turtle nesting season than outside the turtle nesting season when turtles are not concentrated at Raine Island. Turtles showed area-restricted search behaviour around Raine Island for ~3–4 months during the nesting period (November–February). This was followed by direct movement (transit) to putative foraging grounds mostly in the Torres Straight where they switched to area-restricted search mode again, and remained resident for the remainder of the deployment (53–304 days). In contrast, tiger sharks displayed high spatial and temporal variation in movement behaviour which was not closely linked to the movement behaviour of green turtles or recognised turtle foraging grounds. On average, tiger sharks were concentrated around Raine Island throughout the year. While information on diet is required to determine whether tiger sharks are turtle specialists our results support the hypothesis that they target this predictable and plentiful prey during turtle nesting season, but they might not focus on this less predictable food source outside the nesting season.

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Smartphone applications are getting more and more popular and pervasive in our daily life, and are also attractive to malware writers due to their limited computing source and vulnerabilities. At the same time, we possess limited understanding of our opponents in cyberspace. In this paper, we investigate the propagation model of SMS/MMS-based worms through integrating semi-Markov process and social relationship graph. In our modeling, we use semi-Markov process to characterize state transition among mobile nodes, and hire social network theory, a missing element in many previous works, to enhance the proposed mobile malware propagation model. In order to evaluate the proposed models, we have developed a specific software, and collected a large scale real-world data for this purpose. The extensive experiments indicate that the proposed models and algorithms are effective and practical. © 2014 Elsevier Ltd. All rights reserved.

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We reconstructed the nutrient source for egg synthesis by sampling Black-headed Gull (Larus ridibundus) eggs for yolk, analyzing their carbon stable isotope ratio, and comparing that to hatchling down. Most of the variation in carbon stable isotope ratio was explained by differences between nests, the within-nest variation being explained by laying order. These data indicate significant differences in diet choice between individual females and changes in food choice or body-store dynamics during egg laying. Among-egg variation in the carbon stable isotope ratios of the yolk were closely reflected in the hatchling down, on average down being enriched by 3.1‰ δ13C relative to yolk. Our findings support the contention that pre-laying female diets can be evaluated from hatchling down.

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In this paper, I take inspiration from some themes in Ann Murphy’s recent book, Violence and the Philosophical Imaginary, especially her argument that philosophy’s identity and relation to itself depends on an intimate relationship with that which is designated as not itself (e.g. other academic disciplines and non-philosophy in general), the latter of which is a potential source of shame that calls for some form of response. I argue that this shame is particularly acute in regard to the natural sciences, which have gone on in various ways to distance themselves from their progenitor discipline and to achieve both agreement and technical progress in a way that could never be said of philosophy. I trace out some of the reactions to this shame that have dominated in the twentieth century and been a factor in the so-called analytic-continental ‘divide’. The options here are many and varied, but they range from cannibalism (philosophy as queen of the sciences, thus conferring some of the prestige of science upon the philosophy, which alone can unite or ground the various ontic sciences), scientific naturalism (the philosopher defers to the sciences, and most forms of meta-philosophy are rejected as an outmoded remnant of first philosophy), or some kind of irenic separatism about methods or domains such that science and philosophy do not encroach upon the territory of each other. My aims here are mainly diagnostic, but I will indicate where I think that certain responses to this shame are unproductive and unhelpful, with divergent weaknesses associated with the traditions that have come to be labelled ‘analytic’ and ‘continental’ respectively. My tacit suggestion, then, is that philosophy needs to become post-analytic and meta-continental, but I will also briefly criticize some recent efforts to do precisely this in what is sometimes called the ‘scientific turn’ in contemporary continental (or post-continental) philosophy.

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This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Skull structure is intimately associated with feeding ability in vertebrates, both in terms of specific performance measures and general ecological characteristics. This study quantitatively assessed variation in the shape of the cranium and mandible in varanoid lizards, and its relationship to structural performance (von Mises strain) and interspecific differences in feeding ecology. Geometric morphometric and linear morphometric analyses were used to evaluate morphological differences, and finite element analysis was used to quantify variation in structural performance (strain during simulated biting, shaking and pulling). This data was then integrated with ecological classes compiled from relevant scientific literature on each species in order to establish structure-function relationships. Finite element modelling results showed that variation in cranial morphology resulted in large differences in the magnitudes and locations of strain in biting, shaking and pulling load cases. Gracile species such as Varanus salvadorii displayed high strain levels during shaking, especially in the areas between the orbits. All models exhibit less strain during pull back loading compared to shake loading, even though a larger force was applied (pull =30N, shake = 20N). Relationships were identified between the morphology, performance, and ecology. Species that did not feed on hard prey clustered in the gracile region of cranial morphospace and exhibited significantly higher levels of strain during biting (P = 0.0106). Species that fed on large prey clustered in the elongate area of mandible morphospace. This relationship differs from those that have been identified in other taxonomic groups such as crocodiles and mammals. This difference may be due to a combination of the open 'space-frame' structure of the varanoid lizard skull, and the 'pull back' behaviour that some species use for processing large prey.