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Testable Hypotheses (testable + hypothesis)
Selected AbstractsOrganization Structure from a Loose Coupling Perspective: A Multidimensional Approach,DECISION SCIENCES, Issue 2 2001Rafik I. Beekun Abstract Organizational theories frequently rely on notions of sharing and dependence among organizational participants, but researchers usually focus on characteristics of the actors themselves instead of the relational patterns among the actors. Loose coupling is one conceptual tool that emphasizes relational patterns. Loose coupling, however, is an abstract metaphor that is simultaneously fertile and ambiguous. This paper develops a rigorous and comprehensive framework that sharpens the theoretical contributions of loose coupling to our understanding of structural relationships. Characteristics of loose coupling capture some important and underexplored features of multidimensional fit and interdependence in organizations. The proposed framework clarifies these theoretical contributions of loose coupling with concepts and equations modified from network analysis. Testable hypotheses are proposed with respect to three key independent variables that may affect patterns of coupling: organization strategy, technology, and environmental turbulence. Additional hypotheses are advanced with respect to the use of the multidimensional approach to loose coupling in studying new organizational forms. Initial psychometric and empirical evidence are presented. [source] Valid electrodermal hyporeactivity for depressive suicidal propensity offers links to cognitive theoryACTA PSYCHIATRICA SCANDINAVICA, Issue 5 2009L.-H. Thorell Objective:, Studies from three independent laboratories report varying relationships between electrodermal hyporeactivity and suicidal behavior in depressed patients. The aims of this study were to explain that variation, to assess the discriminative validity of electrodermal hyporeactivity for suicide and suicide attempts and to suggest a tentative explanation model. Method:, A meta-analysis was performed of 279 depressed patients and 59 healthy subjects. Results:, The sensitivity was 96.6% and specificity 92.9% of electrodermal hyporeactivity for suicide and 83.3% and 92.7%, respectively, for suicide and/or violent attempts. The shares of hyporeactives were strongly significantly and greatly larger in high than in low suicidal propensity groups, P- value ranging from 4.7 × 10,8 to 1.1 × 10,14. Conclusion:, The high discriminative validity and the emerging links over a proposed interest-limiting precognitive set to cognitive theory of suicide encourage clinical application of tests of electrodermal reactivity. The study offers a series of testable hypotheses constituting a new platform for suicidological research in depression. [source] An automated in situ hybridization screen in the medaka to identify unknown neural genesDEVELOPMENTAL DYNAMICS, Issue 3 2005Carole Deyts Abstract Despite the fact that a large body of factors that play important roles in development are known, there are still large gaps in understanding the genetic pathways that govern these processes. To find previously unknown genes that are expressed during embryonic development, we optimized and performed an automated whole-mount in situ hybridization screen on medaka embryos at the end of somitogenesis. Partial cDNA sequences were compared against public databases and identified according to similarities found to other genes and gene products. Among 321 isolated genes showing specific expression in the central nervous system in at least one of five stages of development, 55.14% represented genes whose functions are already documented (in fish or other model organisms). Additionally, 16.51% were identified as conserved unknown genes or genes with unknown function. We provide new data on eight of these genes that presented a restricted expression pattern that allowed for formulating testable hypotheses on their developmental roles, and that were homologous to mammalian molecules of unknown function. Thus, gene expression screening in medaka is an efficient tool for isolating new regulators of embryonic development, and can complement genome-sequencing projects that are producing a high number of genes without ascribed functions. Developmental Dynamics 234:698,708, 2005. © 2005 Wiley-Liss, Inc. [source] Disease, deficit or denial?ACTA PSYCHIATRICA SCANDINAVICA, Issue 1 2005Models of poor insight in psychosis Objective:, To examine the evidence for the three kinds of aetiological model that dominate the current literature on poor insight in psychosis: clinical models, the neuropsychological model, and the psychological denial model. Method:, Studies pertaining to one or more of these aetiological models were identified, reviewed and critically evaluated. Results:, There is little support for clinical models, partly because they lack testable hypotheses. Several studies reveal a positive relationship between insight and executive function, which may be related to frontal lobe dysfunction. However, the extent to which this relationship is specific and independent of general cognitive impairment remains unclear. There is tentative evidence to support the psychological denial model. Recent data combining the latter two approaches suggest that multiple factors contribute to poor insight. Conclusion:, Integration of different aetiological models is necessary for a fuller understanding of insight in psychosis. Future research should assess multiple aetiological mechanisms in single investigations. [source] A pragmatic approach to estimating the distributions and spatial requirements of the medium- to large-sized mammals in the Cape Floristic Region, South AfricaDIVERSITY AND DISTRIBUTIONS, Issue 1-2 2001A. F. Boshoff Conservation planning in the Cape Floristic Region, a recognized world plant diversity hotspot, required systematic information on the estimated distributions and spatial requirements of the medium- to large-sized mammals within each of 102 Broad Habitat Units delineated according to key biophysical parameters. As a consequence of a general lack of data, we derived a pragmatic approach for obtaining estimates of these two parameters. Distribution estimates were based on a combination of a literature survey (with emphasis on early texts) and the ecological requirements of the species. Spatial requirement estimates were derived from a simple spreadsheet model that is based on forage availability estimates and the metabolic requirements of the mammals in question. Our analysis incorporated adaptations of the agriculture-based Large Stock Unit or Animal Unit approach. The predictions of the model were tested by comparing them with actual density data. The outcomes provided realistic estimates of the two parameters. However, they should be considered as testable hypotheses and the concept of adaptive management , or management by hypothesis , must apply. Examples of the outcomes are provided in the form of maps and tables. [source] Spatial pattern of adult trees and the mammal-generated seed rain in the Iberian pearECOGRAPHY, Issue 3 2010Jose M. Fedriani The degree to which plant individuals are aggregated or dispersed co-determines how a species uses resources, how it is used as a resource, and how it reproduces. Quantifying such spatial patterns, however, presents several methodological issues that can be overcome by using spatial point pattern analyses (SPPA). We used SPPA to assess the distribution of P. bourgaeana adult trees and their seeds (within fecal samples) dispersed by three mammals (badger, fox, and wild boar) within a 72-ha plot across a range of spatial scales. Pyrus bourgaeana trees in our study plot (n=75) were clearly aggregated with a critical spatial scale of ca 25,m, and approximately nine randomly distributed tree clusters were identified. As expected from their marking behaviors, the spatial patterns of fecal deposition varied widely among mammal species. Whereas badger feces and dispersed seeds were clearly clustered at small spatial scales (<10,m), boar and fox feces were relatively scattered across the plot. A toroidal shift null model testing for independence indicated that boars tended to deliver seeds to the vicinity of adult trees and thus could contribute to the maintenance and enlargement of existing tree clusters. Badgers delivered feces and seeds in a highly clumped pattern but unlike boars, away from P. bourgaeana neighborhoods; thus, they are more likely to create new tree clusters than boars. The strong tree aggregation is likely to be the result of one or several non-exclusive processes, such as the spatial patterning of seed delivery by dispersers and seedling establishment beneath mother trees. In turn, the distinctive distribution of P. bourgaeana in Doñana appeared to interact with the foraging behavior of its mammalian seed dispersers, leading to neighbourhood-specific dispersal patterns and fruit-removal rates. Our study exemplifies how a detailed description of patterns generates testable hypotheses concerning the ecology of zoochorous. Pyrus bourgaeana dispersers were unique and complementary in their spatial patterning of seed delivery, which likely confers resilience to their overall service and suggests lack of redundancy and expendability of any one species. [source] Emphasizing interpersonal factors: an extension of the Witkiewitz and Marlatt relapse modelADDICTION, Issue 8 2009Dorian Hunter-Reel ABSTRACT Aim Recently, Witkiewitz & Marlatt reformulated the Marlatt & Gordon relapse model to account for current research findings. The present paper aims to extend this model further to incorporate social variables more fully. Methods The social-factors and alcohol-relapse literatures were reviewed within the framework of the reformulated relapse model. Results The literature review found that the number of social network members, investment of the individual in the social network, levels of general and alcohol-specific support available within the social network and specific behaviors of network members all predict drinking outcomes. However, little is known about the mechanisms by which these social variables influence outcomes. The authors postulate that social variables influence outcomes by affecting intra-individual factors central to the reformulated relapse prevention model, including processes (e.g. self-efficacy, outcome expectancies, craving, motivation, negative affective states) and behaviors (e.g. coping and substance use). The authors suggest specific hypotheses and discuss methods that can be used to study the impact of social factors on the intra-individual phenomena that contribute to relapse. Conclusion The proposed extension of the relapse model provides testable hypotheses that may guide future alcohol-relapse research. [source] The Influence of Gonadal Hormones on Neuronal Excitability, Seizures, and Epilepsy in the FemaleEPILEPSIA, Issue 9 2006Helen E. Scharfman Summary:, It is clear from both clinical observations of women, and research in laboratory animals, that gonadal hormones exert a profound influence on neuronal excitability, seizures, and epilepsy. These studies have led to a focus on two of the primary ovarian steroid hormones, estrogen and progesterone, to clarify how gonadal hormones influence seizures in women with epilepsy. The prevailing view is that estrogen is proconvulsant, whereas progesterone is anticonvulsant. However, estrogen and progesterone may not be the only reproductive hormones to consider in evaluating excitability, seizures, or epilepsy in the female. It seems unlikely that estrogen and progesterone would exert single, uniform actions given our current understanding of their complex pharmacological and physiological relationships. Their modulatory effects are likely to depend on endocrine state, relative concentration, metabolism, and many other factors. Despite the challenges these issues raise to future research, some recent advances have helped clarify past confusion in the literature. In addition, testable hypotheses have developed for complex clinical problems such as "catamenial epilepsy." Clinical and animal research, designed with the relevant endocrinological and neurobiological issues in mind, will help advance this field in the future. [source] Neuroendocrine pathways of addictive behaviourADDICTION BIOLOGY, Issue 3-4 2004F Kiefer Alcohol intake is known to modulate plasma concentrations of neuroendocrine peptides. However, recent results suggest that the endocrine system may not only respond passively to alcohol intake but that, vice versa, it also actively modulates alcohol intake behaviour. The most coherent body of data concerns the hypothalamo,-,pituitary,-,adrenocortical (HPA) axis, with low corticotrophin-releasing hormone (CRH) being associated with more intense craving and increased probability of relapse after acute detoxification. Leptin, ,-endorphin and atrial natriuretic peptide (ANP), which indirectly regulate the HPA system, also may modulate the intensity of craving or the intensity of the alcohol withdrawal syndrome. Although most of the currently available data demonstrate association rather than causality between neuroendocrine changes and alcohol-related behaviours, they do provide testable hypotheses and open up perspectives of treating alcohol dependence via manipulation of the neuroendocrine axis. [source] Control of eye orientation: where does the brain's role end and the muscle's begin?EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2004Dora E. Angelaki Abstract Our understanding of how the brain controls eye movements has benefited enormously from the comparison of neuronal activity with eye movements and the quantification of these relationships with mathematical models. Although these early studies focused on horizontal and vertical eye movements, recent behavioural and modelling studies have illustrated the importance, but also the complexity, of extending previous conclusions to the problems of controlling eye and head orientation in three dimensions (3-D). An important facet in understanding 3-D eye orientation and movement has been the discovery of mobile, soft-tissue sheaths or ,pulleys' in the orbit which might influence the pulling direction of extraocular muscles. Appropriately placed pulleys could generate the eye-position-dependent tilt of the ocular rotation axes which are characteristic for eye movements which follow Listing's law. Based on such pulley models of the oculomotor plant it has recently been proposed that a simple two-dimensional (2-D) neural controller would be sufficient to generate correct 3-D eye orientation and movement. In contrast to this apparent simplification in oculomotor control, multiple behavioural observations suggest that the visuo-motor transformations, as well as the premotor circuitry for saccades, pursuit eye movements and the vestibulo-ocular reflexes, must include a neural controller which operates in 3-D, even when considering an eye plant with pulleys. This review summarizes the most recent work and ideas on this controversy. In addition, by proposing directly testable hypotheses, we point out that, in analogy to the previously successful steps towards elucidating the neural control of horizontal eye movements, we need a quantitative characterization first of motoneuron and next of premotor neuron properties in 3-D before we can succeed in gaining further insight into the neural control of 3-D motor behaviours. [source] The utility of behavioral models and modules in molecular analyses of social behaviorGENES, BRAIN AND BEHAVIOR, Issue 3 2008Andrew B. Barron It is extremely difficult to trace the causal pathway relating gene products or molecular pathways to the expression of behavior. This is especially true for social behavior, which being dependent on interactions and communication between individuals is even further removed from molecular-level events. In this review, we discuss how behavioral models can aid molecular analyses of social behavior. Various models of behavior exist, each of which suggest strategies to dissect complex behavior into simpler behavioral ,modules.' The resulting modules are easier to relate to neural processes and thus suggest hypotheses for neural and molecular function. Here we discuss how three different models of behavior have facilitated understanding the molecular bases of aspects of social behavior. We discuss the response threshold model and two different approaches to modeling motivation, the state space model and models of reinforcement and reward processing. The examples we have chosen illustrate how models can generate testable hypotheses for neural and molecular function and also how molecular analyses probe the validity of a model of behavior. We do not champion one model over another; rather, our examples illustrate how modeling and molecular analyses can be synergistic in exploring the molecular bases of social behavior. [source] Multiple hypothesis evaluation in auditingACCOUNTING & FINANCE, Issue 3 2002Rajendra P. Srivastava In many audit tasks, auditors evaluate multiple hypotheses to diagnose the situation. Research suggests this is a complex task that individuals have difficulty performing. Further, there is little guidance in professional standards or literature dealing with the many complexities present in the audit environment. Using probability theory, this study derives the appropriate revision of likelihoods for multiple hypotheses given different realistic audit conditions. The analysis shows that the relationships among the hypotheses dramatically impact the use of audit evidence and the resulting pattern of probability revisions. We also identify testable hypotheses to guide future research and discuss practice implications regarding ways to improve the effectiveness of analytical procedures. [source] Hyperlinking Audited Financial Statements to Unaudited Information in the Presence of the WebTrust Logo: Hodge's Model RevisedINTERNATIONAL JOURNAL OF AUDITING, Issue 2 2003Ruth V. Pike This paper identifies a possible relationship between WebTrust, initiated by the AICPA/CICA as an attestation service for web sites, and the potentially misleading effect of hyperlinking audited financial statements to unaudited information. We argue that firms hyperlinking such information increase the perceived credibility of the unaudited information, which may be exacerbated by the presence of a recognisable, symbolically trustworthy logo. We formulate testable hypotheses by modifying an existing theoretical framework which relates to hyperlinked materials and their effect on investor judgements. The amended model extends to all potential users of financial information and incorporates the web-based assurance logo of WebTrust. We anticipate that this model will become instrumental in determining the extent of any expectation gap regarding user perceptions, thus facilitating the process of recommending policies to eliminate the potentially misleading effects of web-based financial information and therefore limiting the risk of corporate fraud and the legal liability of auditors. [source] Explaining Migration: A Critical ViewINTERNATIONAL SOCIAL SCIENCE JOURNAL, Issue 165 2000Joaquín Arango The article surveys the major contemporary explanations of migration, starting with the neo-classical theory, and then the array of theories and conceptual frameworks that have flourished in the last quarter of the century. The survey highlights the fact that in its relatively short history, theorising about migration has taken the form of a string of separate, generally unconnected theories, models, conceptual frameworks and empirical generalisations, rather than a cumulative sequence of contributions. As awhole, existing theories of migration can be faulted for focusing almost exclusively on the explanation of the causes of migration, to the detriment of other dimensions; for making ,grand claims' out of proportion with effective explanatory power; and for providing explanations ex-post rather than guiding empirical research and providing testable hypotheses. In addition to the difficulties that all the social sciences experience when trying to explainhuman behaviour, migration theories face special ones: its subject matter is hard to define, difficult to measure, extremely multifaceted and multiform, and thus resistant to theory-building. Whilst the reservoir of theories, and especially of conceptual frameworks, available nowadays represents a clear improvement over the situation a few decades ago, their contribution toour knowledge of migration is still limited. [source] What Is Your Research Program?INTERNATIONAL STUDIES QUARTERLY, Issue 1 2005Some Feminist Answers to International Relations Methodological Questions Methodological issues have constituted some of the deepest sources of misunderstanding between International Relations (IR) feminists and IR theorists working in social scientific frameworks. IR theorists have called upon feminists to frame their research questions in terms of testable hypotheses. Feminists have responded that their research questions cannot be answered using social science explanatory frameworks. Deep epistemological divisions about the construction and purpose of knowledge make bridging these methodological divides difficult. These epistemological standards lead feminists to very different methodological perspectives. Asking different questions from those typically asked in IR, many IR feminists have drawn on ethnographic, narrative, cross-cultural, and other methods that are rarely taught to students of IR, to answer them. Drawing on a range of interdisciplinary scholarship on feminist methodologies and some recent IR feminist case studies, this article analyzes and assesses how these methodological orientations are useful for understanding the gendering of international politics, the state and its security-seeking practices and its effects on the lives of women and men. [source] Comparison of developmental trajectories in the starlet sea anemone Nematostella vectensis: embryogenesis, regeneration, and two forms of asexual fissionINVERTEBRATE BIOLOGY, Issue 2 2007Adam M. Reitzel Abstract. The starlet sea anemone, Nematostella vectensis, is a small burrowing estuarine animal, native to the Atlantic coast of North America. In recent years, this anemone has emerged as a model system in cnidarian developmental biology. Molecular studies of embryology and larval development in N. vectensis have provided important insights into the evolution of key metazoan traits. However, the adult body plan of N. vectensis may arise via four distinct developmental trajectories: (1) embryogenesis following sexual reproduction, (2) asexual reproduction via physal pinching, (3) asexual reproduction via polarity reversal, and (4) regeneration following bisection through the body column. Here, we compare the ontogenetic sequences underlying alternate developmental trajectories. Additionally, we describe the predictable generation of anomalous phenotypes that can occur following localized injuries to the body column. These studies suggest testable hypotheses on the molecular mechanisms underlying alternate developmental trajectories, and they provoke new questions about the evolution of novel developmental trajectories and their initiation via environmental cues. [source] Philosophical Anthropology Can Help Social Scientists Learn from Empirical TestsJOURNAL FOR THE THEORY OF SOCIAL BEHAVIOUR, Issue 3 2007JOHN WETTERSTEN ABSTRACT Popper's theory of demarcation has set the standard of falsifiability for all sciences. But not all falsifiable theories are part of science and some tests of scientific theories are better than others. Popper's theory has led to the banning of metaphysical and/or philosophical anthropological theories from science. But Joseph Agassi has supplemented Popper's theory to explain how such theories are useful as research programs within science. This theory can also be used to explain how interesting tests may be found. Theories of rationality may be used to illustrate this point by showing how they fail or succeed in producing interesting and testable hypotheses in the social sciences. [source] Predicting the effects of perturbations on ecological communities: what can qualitative models offer?JOURNAL OF ANIMAL ECOLOGY, Issue 5 2005DAVE RAMSEY Summary 1Quantitative predictions of the effects of perturbations on communities of interacting species have often proved to be difficult. However, if precise predictions are not a requirement then qualitative models of community dynamics offer an alternative method for predicting species responses to perturbations. 2We used two qualitative modelling approaches to predict the effects of predator control on the fledging rate of an endangered New Zealand bird, the North Island kokako. The first approach was based on loop analysis and provided predictions on the probable direction of change in species abundances to single species perturbations. The second approach, ,fuzzy interaction webs', used fuzzy logic in the framework of a fuzzy cognitive map to provide predictions on the probable magnitude of change in species abundances to perturbations. 3Using both methods, we predicted the qualitative change in the equilibrium fledging rates of kokako under various regimes of single- and multispecies predator control (ship rats, brushtail possums and stoats). Single species control was insufficient to lift the fledging rate from ,low' to ,moderate'. However, simultaneous control of both ship rats and possums had the greatest influence on the fledging rates compared with any other combination as a result of the additional indirect effect of ship rat control on stoat abundance. 4We propose qualitative modelling of community dynamics as a method suitable for predicting the effects of perturbations in complex ecological communities that can encapsulate diverse sources of knowledge about food web interactions. We believe that these methods are a useful set of heuristic tools that can be used to propose testable hypotheses about ecosystem functioning that can complement existing statistical and quantitative modelling approaches. [source] Impacts of land use change on South-east Asian forest butterflies: a reviewJOURNAL OF APPLIED ECOLOGY, Issue 4 2007LIAN PIN KOH Summary 1South-east Asia has the highest relative rate of habitat loss and degradation in the humid tropics. The responses of less ,charismatic' groups, including butterflies, to habitat disturbance remain relatively poorly understood. Many South-east Asian butterflies are endemic to the region and face global extinction if current levels of deforestation were to continue. 2Here, I highlight South-east Asia as a region urgently in need of butterfly conservation research and review empirical studies of the responses of South-east Asian butterflies to land use change. Additionally, I discuss some methodological pitfalls for such studies. Furthermore, I argue for the importance of identifying the ecological correlates of sensitivity of butterfly species to forest modification and the potential biological mechanisms underlying their responses to land use change. 3There has been no consensus among previous studies on the effects of land use change on butterfly communities in South-east Asia. Of the 20 studies I reviewed, seven reported higher species richness/diversity in undisturbed (or the least disturbed) forest than in disturbed habitats, nine reported the opposite trend, three reported no difference and one reported a strong influence of seasonality on the impacts of logging. 4Some of these studies may contain inherent methodological biases resulting from the failure to control for sampling effects, the lack of consideration for the spatial scale of analysis and incomplete sampling of the vertical strata in tropical rainforests. 5Synthesis and applications. Empirical studies of the effects of land use change on tropical forest insects are sorely lacking from South-east Asia. Butterflies are an ideal taxonomic group for such investigations. Future studies should be designed carefully to avoid the methodological pitfalls highlighted here. Determining the ecological correlates of sensitivity of butterflies to forest modification is important for the pre-emptive identification of species of conservation concern and for generating testable hypotheses on the differential responses of species to forest modification. Experimental studies are needed to determine the mechanisms underlying the responses of species to land use change in order to develop effective strategies for the conservation of butterflies in human disturbed landscapes. [source] Refining the stress-gradient hypothesis for competition and facilitation in plant communitiesJOURNAL OF ECOLOGY, Issue 2 2009Fernando T. Maestre Summary 1The stress-gradient hypothesis (SGH) predicts that the frequency of facilitative and competitive interactions will vary inversely across abiotic stress gradients, with facilitation being more common in conditions of high abiotic stress relative to more benign abiotic conditions. With notable exceptions, most tests of the SGH have studied the interaction between a single pair or a few pairs of species, and thus have evaluated shifts in the magnitude and direction of pair-wise interactions along stress gradients, rather than shifts in the general frequency of interactions. 2The SGH has been supported by numerous studies in many ecosystems, has provided a crucial foundation for studying the interplay between facilitation and competition in plant communities, and has a high heuristic value. However, recent empirical research indicates that factors like the variation among species and the nature of the stress gradient studied add complexity not considered in the SGH, creating an opportunity to extend the SGH's general conceptual framework. 3We suggest that one approach for extending the SGH framework is to differentiate between the original idea of how ,common' interactions might be along stress gradients and the ubiquitous empirical approach of studying shifts in the strength of pair-wise interactions. Furthermore, by explicitly considering the life history of the interacting species (relative tolerance to stress vs. competitive ability) and the characteristics of the stress factor (resource vs. non-resource) we may be able to greatly refine specific predictions relevant to the SGH. 4We propose that the general pattern predicted by the SGH would hold more frequently for some combinations of life histories and stress factor, particularly when the benefactor and beneficiary species are mostly competitive and stress-tolerant, respectively. However, we also predict that other combinations are likely to yield different results. For example, the effect of neighbours can be negative at both ends of the stress gradient when both interacting species have similar ,competitive' or ,stress-tolerant' life histories and the abiotic stress gradient is driven by a resource (e.g. water). 5Synthesis. The extension of the SGH presented here provides specific and testable hypotheses to foster research and helps to reconcile potential discrepancies among previous studies. It represents an important step in incorporating the complexity and species-specificity of potential outcomes into models and theories addressing how plant,plant interactions change along stress gradients. [source] Size-specific growth of bluegill, largemouth bass and channel catfish in relation to prey availability and limnological variablesJOURNAL OF FISH BIOLOGY, Issue 1 2007D. E. Shoup Growth of sympatric populations of three important sport fish species: bluegill Lepomis macrochirus, largemouth bass Micropterus salmoides and channel catfish Ictalurus punctatus, in 14 Illinois reservoirs was assessed in an attempt to relate size-specific growth to environmental conditions. Multiple regression relationships for most species and size classes explained a large percentage of the variation in growth. Growth of small bluegill (50 mm total length, LT) showed a strong negative relationship with bluegill catch per unit effort (cpue), per cent littoral area and pH. Large bluegill (150 mm LT) growth was negatively related to Daphnia spp. and benthic macroinvertebrate abundance and lake volume, and positively related to bluegill cpue. Growth of small (100 mm LT) and large (250 mm LT) largemouth bass was not well explained by any of the measured variables. Growth of both small (300 mm LT) and large (450 mm LT) channel catfish was strongly positively related to forage fishes and ichthyoplankton abundance, and per cent littoral area while negatively related to benthic macroinvertebrates. By identifying environmental conditions associated with increased growth rates, these models provide direction for managing fish populations and suggest testable hypotheses for future study of the complex interactions between environmental conditions and growth. [source] Factors influencing the incidence and prevalence of food allergyALLERGY, Issue 9 2009S. Cochrane Food allergy is an increasing problem in Europe and elsewhere and severe reactions to food are also becoming more common. As food allergy is usually associated with other forms of allergic sensitisation it is likely that many risk factors are common to all forms of allergy. However the potential severity of the disease and the specific public heath measures required for food allergy make it important to identify the specific risk factors for this condition. Food allergy is unusual in that it often manifests itself very early in life and commonly remits with the development of tolerance. Hypotheses that explain the distribution of food allergy include specific genetic polymorphisms, the nature of the allergens involved and the unique exposure to large quantities of allergen through the gut. Progress has been made in developing more specific and testable hypotheses but the evidence for any of these is still only preliminary. Further collaborative research is required to develop an appropriate public health response to this growing problem. [source] A scalar analysis of landscape connectivityOIKOS, Issue 2 2003Article first published online: 4 JUL 200 Landscape connectivity is critical to the maintenance of spatially-structured populations and consists of both a structural component, which describes the shape, size and location of landscape features; and a biological component, which consists of both the response of individuals to landscape features, and the patterns of gene flow that result from those individual responses. Traditional studies of landscape connectivity have attempted to discern individual behavioral responses to landscape features, but this methodology is intractable for many species. This paper is an attempt to relate the components of landscape connectivity through the explicit treatment of their spatial and temporal scales. Traditional measures of structural and biological components of connectivity are reviewed and more recently developed methods for the analysis of scale for each are introduced. I then present a framework for the comparison of scalar phenomena based on Watt's unit pattern, describe the potential outcomes of the comparison and discuss the implications of each. Several testable hypotheses emerge from the analysis that may serve as a useful framework for the investigation of landscape connectivity in the future. [source] Reproductive ecology and the endometrium: Physiology, variation, and new directionsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue S49 2009Kathryn B.H. Clancy Abstract Endometrial function is often overlooked in the study of fertility in reproductive ecology, but it is crucial to implantation and the support of a successful pregnancy. Human female reproductive physiology can handle substantial energy demands that include the production of fecund cycles, ovulation, fertilization, placentation, a 9-month gestation, and often several years of lactation. The particular morphology of the human endometrium as well as our relative copiousness of menstruation and large neonatal size suggests that endometrial function has more resources allocated to it than many other primates. The human endometrium has a particularly invasive kind of hemochorial placentation and trophoblast that maximizes surface area and maternal,fetal contact, yet these processes are actually less efficient than the placentation of some of our primate relatives. The human endometrium and its associated processes appear to prioritize maximizing the transmission of oxygen and glucose to the fetus over efficiency and protection of maternal resources. Ovarian function controls many aspects of endometrial function and thus variation in the endometrium is often a reflection of ecological factors that impact the ovaries. However, preliminary evidence and literature from populations of different reproductive states, ages and pathologies also suggests that ecological stress plays a role in endometrial variation, different from or even independent of ovarian function. Immune stress and psychosocial stress appear to play some role in the endometrium's ability to carry a fetus through the mechanism of inflammation. Thus, within reproductive ecology we should move towards a model of women's fecundity and fertility that includes many components of ecological stress and their effects not only on the ovaries, but on processes related to endometrial function. Greater attention on the endometrium may aid in unraveling several issues in hominoid and specifically human evolutionary biology: a low implantation rate, high rates of early pregnancy loss, prenatal investment in singletons but postnatal support of several dependent offspring at once, and higher rate of reproductive and pregnancy-related pathology compared to other primates, ranging from endometriosis to preeclampsia. The study of the endometrium may also complicate some of these issues, as it raises the question of why humans have a maximally invasive placentation method and yet slow fetal growth rates. In this review, I will describe endometrial physiology, methods of measurement, variation, and some of the ecological variables that likely produce variation and pregnancy losses to demonstrate the necessity of further study. I propose several basic avenues of study that leave room for testable hypotheses in the field of reproductive ecology. And finally, I describe the potential of this work not just in reproductive ecology, but in the resolution of broader women's health issues. Yrbk Phys Anthropol 52:137,154, 2009. © 2009 Wiley-Liss, Inc. [source] Annotation: The therapeutic alliance , a significant but neglected variable in child mental health treatment studiesTHE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 5 2006Jonathan Green Background:, There has been relatively little research into therapeutic alliance in child and adolescent mental health and virtually no incorporation of alliance measures as a variable in treatment trials in Child and Adolescent Mental Health Services (CAMHS). Method:, A selective literature review on studies in therapeutic alliance in adulthood and childhood along with a theoretical formulation of possible mechanisms of alliance. Results:, Therapeutic alliance is reliably measurable both by observation and questionnaire methods at all points in the treatment cycle. In both adult and child studies it shows a consistent, albeit modest, association with treatment outcome. In specific adult studies it has shown a high predictive validity in relation to outcome compared to other variables. In child studies alliance is particularly salient in externalising disorder and predicts outcome of inpatient treatment. Child alliance and parental alliance are independent factors. Theoretical models of alliance outlined in this paper suggest testable hypotheses regarding predictors for positive and negative alliance. Conclusions:, Therapeutic alliance in CAMHS is measurable and worth measuring. It is likely to be an important variable for treatment outcome studies and should be included in future trial designs. [source] Linking Product Development Outcomes to Market Valuation of the Firm: The Case of the U.S. Pharmaceutical Industry,THE JOURNAL OF PRODUCT INNOVATION MANAGEMENT, Issue 5 2004Anurag Sharma The purpose of this research was to examine empirically the effects of new product development outcomes on overall firm performance. To do so, first product development and finance literature were connected to develop three testable hypotheses. Next, an event study was conducted in order to explore whether the changes in the stock market valuation of firms are influenced by the outcomes of efforts to develop new products. The pharmaceutical industry was chosen as the empirical context for the present study's analysis largely because the gate-keeping role played by the Food and Drug Administration (FDA) provides a specific event date on which to focus the event study methodology. As such, this study's events were dates of public announcements of the FDA decisions to approve or to reject the New Drug Applications submitted by the sponsoring firms. Consistent with the efficient market hypothesis, this study's results show that market valuations are responsive strongly and cleanly to the success or failure of new product development efforts. Hence, one of this study's key results suggests that financial markets may be attuned sharply to product development outcomes in publicly traded firms. This study also finds that financial market losses from product development failures were much larger in magnitude than financial market gains from product development successes,indicating an asymmetry in the response of financial markets to the success and failure of new product development efforts. Hence, another implication of this study's results is that managers should factor in a substantial risk premium when considering substantial new development projects. The present study's results also imply that managers should refrain from hyping new products and perhaps even should restrain the enthusiasm that the financial community may build before the product fully is developed. The effect on firm value is severe when expectations about an anticipated new product are not fulfilled. Managers in effect should take care to build reasonable and realistic expectations about potential new products. [source] Linking ecological and hydromorphological data: approaches, challenges and future prospects for riverine scienceAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue S1 2010I. P. Vaughan Abstract 1.Research linking river ecology and hydromorphology is driven by concerns about hydromorphological pressures (e.g. abstraction, land-use change) and legislative (e.g. EU Water Framework Directive) or management needs (e.g. climate-change adaptation). Unfortunately, much of the science is still weak or qualitative (cf. links between ecology and water quality). 2.Rapid progress is required, but financial resources are limited. In response, research opportunities using existing ecological and hydromorphological data and survey methods need to be explored further. 3.There are challenges inherent in using existing data, which are often collected for different purposes, and this paper highlights aspects of spatial scale, temporal coverage, sampling biases, data quality and mining, and the problems faced when using pre-defined sets of variables. 4.While the prospects for exploiting existing data are mixed, distinct strengths arise from extensive geographic coverage, the ability to improve the evidence base rapidly and at low cost, and the generation of testable hypotheses. 5.Current survey methods usually record biological or hydromorphic patterns, or inventories of features (cf. physical processes, or ecosystem functions or services). Their greatest use is likely to be in extending current spatially extensive biological or water chemistry monitoring to more integrated ,eco-hydromorphic' monitoring. 6.With further methodological development, there is real scope for illuminating several aspects of riverine ecology, including the direct ecological and physical consequences of modifying river systems; revealing indirect sensitivity to other pressures, such as climate change; offering a more holistic picture of the distribution of pressures on river ecosystems; and developing hydromorphology as a unifying theme in river studies. However, such developments require funding commitments from research sponsors. Copyright © 2010 John Wiley & Sons, Ltd. [source] Criteria for determining native distributions of biota: the case of the northern plains killifish in the Cheyenne River drainage, North America,AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 1 2009Christopher W. Hoagstrom Abstract 1.Criteria exist to help determine native distributions of species, but they are seldom explicitly used. 2.As an example of their utility, nine revised and expanded criteria are applied to assess the status of northern plains killifish in the Cheyenne River drainage. Use of each criterion is demonstrated. The criteria are: (1) history, (2) detectibility, (3) biogeography, (4) life-history, (5) human affinity, (6) invasion path, (7) invasiveness, (8) phylogenetics, and (9) pre-history. 3.Upon review, only one criterion weakly supports non-native status, whereas five strongly support native status, one weakly supports native status, and two are equivocal. 4.Criteria to determine native distributions provide a rigorous method to assess available information, reveal knowledge gaps, and produce testable hypotheses. As demonstrated here, their consistent use as a cohesive set would greatly improve understanding of species distributions, benefiting conservation efforts and related meta-analyses. Published in 2008 by John Wiley & Sons, Ltd. [source] Variation in stickleback head morphology associated with parasite infectionBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009NIELS J. DINGEMANSE Parasites can affect host phenotypes, influencing their ecology and evolution. Host morphological changes occurring post-infection might result from pathological by-products of infection, or represent adaptations of hosts or parasites. We investigated the morphology of three-spined sticklebacks, Gasterosteus aculeatus, from a population naturally infected with Schistocephalus solidus, which grows to large sizes in their body cavity. We examined local effects of infection on trunk shape, which are imposed directly by the bulk of the growing parasite, and distant effects on head morphology. We show that trunk shape differed between infection classes, and was affected more severely in fish with heavier total parasite mass. We further show unexpected differences in head morphology. The heads of infected fish were reduced in size and differently shaped to those of non-infected fish, with infected fish having deeper heads. Importantly, both head size and shape were also affected more severely in fish with heavier total parasite mass. This latter result suggests that differences in morphology are caused by post-infection changes. Such changes may be incidental, evolutionarily neutral ,side effects' of infection. However, because head morphology affects foraging ecology, such changes are likely to have fitness consequences for hosts, and may constitute adaptations, either of hosts or of parasites. We discuss our finding in the context of the evolution of phenotypic plasticity, and suggest testable hypotheses examining the proximate mechanisms underlying these morphological effects and their potential evolutionary basis. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 759,768. [source] Pattern Bargaining: An Investigation into its Agency, Context and EvidenceBRITISH JOURNAL OF INDUSTRIAL RELATIONS, Issue 1 2008Franz Traxler Pattern bargaining stands out as both an under-researched and controversial subject. This article is an analytical and empirical contribution to this debate. Theoretically, it provides a conceptual framework, which enables analysis to systematically differentiate between distinct forms of pattern bargaining in terms of scope, agency, development and function, which arise from differing contexts in terms of interest configuration, power relations and economic conditions. This framework is used to develop testable hypotheses on pattern bargaining as a mechanism of inter-industry bargaining co-ordination. The empirical part of the article examines these hypotheses for collective bargaining from 1969 to 2004 in Austria, which is commonly seen as a paradigm case of pattern bargaining. The article concludes by highlighting the broader implications its findings have from a cross-nationally comparative perspective. [source] | ||||||||||||||||||||||||||||||||||