Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Hypothesis

  • adaptive hypothesis
  • additional hypothesis
  • adjustment hypothesis
  • alternative hypothesis
  • another hypothesis
  • association hypothesis
  • author hypothesis
  • balance hypothesis
  • basic hypothesis
  • biogeographic hypothesis
  • biogeographical hypothesis
  • buffering hypothesis
  • causal hypothesis
  • cell hypothesis
  • chromalveolate hypothesis
  • competing hypothesis
  • constraint hypothesis
  • contact hypothesis
  • convergence hypothesis
  • current hypothesis
  • different hypothesis
  • dispersal hypothesis
  • disturbance hypothesis
  • ecological hypothesis
  • efficiency hypothesis
  • efficient market hypothesis
  • emerging hypothesis
  • enemy release hypothesis
  • evolutionary hypothesis
  • exclusive hypothesis
  • existing hypothesis
  • expectation hypothesis
  • export-led growth hypothesis
  • first hypothesis
  • functional hypothesis
  • general hypothesis
  • gradient hypothesis
  • growth hypothesis
  • habitat heterogeneity hypothesis
  • heterogeneity hypothesis
  • hygiene hypothesis
  • important hypothesis
  • income hypothesis
  • initial hypothesis
  • interaction hypothesis
  • intermediate disturbance hypothesis
  • key hypothesis
  • latter hypothesis
  • linear hypothesis
  • liquidity hypothesis
  • main hypothesis
  • major hypothesis
  • many hypothesis
  • market hypothesis
  • mechanistic hypothesis
  • morphological hypothesis
  • multivariate hypothesis
  • new hypothesis
  • novel hypothesis
  • null hypothesis
  • numerous hypothesis
  • one hypothesis
  • other hypothesis
  • oxidative stress hypothesis
  • parsimonious hypothesis
  • particular hypothesis
  • pathophysiological hypothesis
  • permanent income hypothesis
  • phylogenetic hypothesis
  • plausible hypothesis
  • porter hypothesis
  • possible hypothesis
  • preliminary hypothesis
  • pressure hypothesis
  • prevailing hypothesis
  • previous hypothesis
  • primary hypothesis
  • prior hypothesis
  • priori hypothesis
  • proposed hypothesis
  • rate hypothesis
  • recent hypothesis
  • refugia hypothesis
  • regulation hypothesis
  • release hypothesis
  • research hypothesis
  • scientific hypothesis
  • second hypothesis
  • selection hypothesis
  • several hypothesis
  • signaling hypothesis
  • specific hypothesis
  • stress gradient hypothesis
  • stress hypothesis
  • stress-gradient hypothesis
  • study hypothesis
  • support hypothesis
  • test hypothesis
  • testable hypothesis
  • testing hypothesis
  • theoretical hypothesis
  • third hypothesis
  • trade-off hypothesis
  • traditional hypothesis
  • true null hypothesis
  • unifying hypothesis
  • various hypothesis
  • world hypothesis

  • Terms modified by Hypothesis

  • hypothesis argue
  • hypothesis generating
  • hypothesis generation
  • hypothesis i
  • hypothesis set
  • hypothesis states
  • hypothesis suggesting
  • hypothesis test
  • hypothesis testing
  • hypothesis testing procedure

  • Selected Abstracts

    Thyroid autoimmunity in children with features of both type 1 and type 2 diabetes

    PEDIATRIC DIABETES, Issue 4pt1 2008
    Ingrid M Libman
    Aim/hypothesis:, To assess the prevalence of autoimmune thyroid disease (ATD) in insulin-treated youth with clinical features of type 2 diabetes mellitus (T2DM). Methods:, We evaluated prevalence of thyroid peroxidase (TPO) and thyroglobulin (TGA) antibodies at onset of insulin-treated diabetes and follow-up in 183 White and Black children. Of these, 136 had a body mass index (BMI) <85th percentile with 122 (89%) positive for ,-cell autoimmunity [type 1 diabetes mellitus (T1DM)/group I], 25 were overweight (BMI ,85thpercentile) with or without acanthosis nigricans with ,-cell autoimmunity [,double' diabetes (DD)/group II], and 22 were overweight with no conventional ,-cell autoantibodies (group III). Results:, The prevalence of TPO and/or TGA was 39 and 29% (p = 0.19) in White and Black children and 39, 32, and 0% (p = 0.007) in groups I, II, and III, respectively. After a median follow-up of 60 months, 3.7, 4.3, and 0% developed hypothyroidism (increased thyroid-stimulating hormone with or without decreased free T4) in groups I, II, and III, respectively (p = 0.6). In subjects with TPO and/or TGA, hypothyroidism developed in 10 and 14% of groups I and II, respectively (p = 0.7). No child without thyroid antibodies developed hypothyroidism. Conclusions:, In patients with clinical features of T2DM who have evidence of ,-cell autoimmunity (DD), the frequency of thyroid antibodies and ATD is similar to that in classical T1DM. This suggests that TIDM comorbidities may be common in clinical T2DM patients who have ,-cell autoimmunity. Despite their obesity, youth with insulin-requiring diabetes should be screened for thyroid and possibly other T1DM-associated autoimmune diseases. [source]

    Psychopathy and offence severity in sexually aggressive and violent youth

    Amber Fougere
    Background,A large proportion of violent crimes are committed by youths. Youths with psychopathic traits may have a higher risk for recidivism and violence. Aims/hypotheses,Our aim was to compare sexually aggressive with violent young men on offence severity and psychopathy. Three hypotheses were proposed: first, young men with previous offences would display a progressive increase in seriousness of offence during their criminal career; secondly, the sexually aggressive and violent young men would not differ in scores on the Hare Psychopathy Checklist: Youth Version (PCL:YV); but, thirdly, PCL:YV scores would be positively correlated with the severity of the index crime, as measured by the Cormier,Lang System for Quantifying Criminal History. Methods,Information was collected from the files of 40 young men in conflict with the law, and the PCL:Youth Version (YV) rated from this by trained raters. Results,The offences of these young men became more serious over time, but we found no association between PCL:YV scores and offence type or seriousness. Conclusions and implications,This exploratory research suggests the importance of understanding the progression in offending careers, but a limited role for the PCL:YV in doing so. Given the small sample size, however, and the limit on access to information about details of age, the findings need replication. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Psychometric properties of the Beck Depression Inventory-II with incarcerated male offenders aged 18,21 years

    Emma J. Palmer
    Background,The Beck Depression Inventory , Second Edition (BDI-II) is a self-report measure of depression. Studies have shown it to have good psychometric properties with adult and adolescent clinical and non-clinical populations. However, this research has mostly been conducted with North American samples. Aims/hypotheses,To examine the psychometric characteristics of the BDI-II with male young adult offenders in the UK. Methods,The BDI-II was administered to 117 incarcerated male young adult offenders aged 18,21 years from the UK. Results,The BDI-II showed good internal consistency and concurrent validity. Factor analysis revealed two factors, relating to cognitive-affective items and somatic items. The items loading on the two factors were very similar to those found in a North American adolescent (13,17 years) psychiatric inpatient sample. Conclusions and implications for future research,The findings suggest that the BDI-II can be used with confidence in young adult male offenders. It would be useful to confirm its psychometric properties in other offender samples and establish offender population norms. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    The projected health care burden of Type 2 diabetes in the UK from 2000 to 2060

    A. Bagust
    Abstract Aims/hypothesis To predict the incidence and prevalence of Type 2 diabetes in the UK, the trends in the levels of diabetes-related complications, and the associated health care costs for the period 2000,60. Methods An established epidemiological and economic model of the long-term complications and health care costs of Type 2 diabetes was applied to UK population projections from 2000 to 2060. The model was used to calculate the incidence and prevalence of Type 2 diabetes, the caseloads and population burden for diabetes-related complications, and annual NHS health care costs for Type 2 diabetes over this time period. Results The total UK population will not increase by more than 3% at any time in the next 60 years. However, the population over 30 will increase by a maximum of 11% by 2030. Due to population ageing, in 2036 there will be approximately 20% more cases of Type 2 diabetes than in 2000. Cases of diabetes-related complications will increase rapidly to peak 20,30% above present levels between 2035 and 2045, before showing a modest decline. The cost of health care for patients with Type 2 diabetes rises by up to 25% during this period, but because of reductions in the economically active age groups, the relative economic burden of the disease can be expected to increase by 40,50%. Conclusion/interpretation In the next 30 years Type 2 diabetes will present a serious clinical and financial challenge to the UK NHS. [source]

    Bacterial composition and red fluorescence of plaque in relation to primary and secondary caries next to composite: an in situ study

    R. Z. Thomas
    Background/hypothesis:, Secondary caries has been suggested as the main reason for restoration replacement. We hypothesized that more caries-associated bacteria are found on composite resin restoration material, compared to sound tooth tissue. Methods:, Both restored and unrestored dentin and enamel samples were placed in a full denture of eight subjects for 20 weeks. The microbiological composition of approximal plaque and the association between caries-associated bacteria and red autofluorescence of dental plaque was studied. Every 4 weeks the specimens were microradiographed using transversal wavelength independent microradiography (T-WIM). After 1 and 20 weeks red fluorescence pictures and plaque samples were taken. Samples were cultured for total anaerobic counts, mutans streptococci, lactobacilli, candida and Actinomyces odontolyticus. Results:, Lesion depth in the dentin and enamel was positively associated with lactobacilli, and lesion depth in dentin was positively associated with A. odontolyticus, whereas no association was found between mutans streptococci and lesion depth. The red-fluorescent bacteria A. odontolyticus and lactobacilli did not correlate with red-fluorescent plaque, indicating that red fluorescence is probably not caused by a single species of these bacteria. After 20 weeks, a higher proportion of combined mutans streptococci and lactobacilli was found on restored tissue compared to non-restored tissue (P = 0.04). Conclusion:, The higher proportion of caries-associated bacteria on restored tissue indicates that the ecology on the surface of primary lesions differs from that on lesions next to composite, and that secondary caries next to composite may differ from the primary caries process. [source]


    EVOLUTION, Issue 1 2010
    Gabriel D. G. Debout
    We investigated sex allocation in the Neotropical ant Allomerus octoarticulatus var. demerarae. Because Allomerus is a plant symbiont, we could make geographically extensive collections of complete colonies and of foundresses in saplings, allowing us to estimate not only population- and colony-level sex allocation but also colony resource levels and the relatednesses of competing ant foundresses. This species exhibits a strongly split sex ratio, with 80% of mature colonies producing ,90% of one sex or the other. Our genetic analyses (DNA microsatellites) reveal that Allomerus has a breeding system characterized by almost complete monogyny and a low frequency of polyandry. Contrary to theoretical explanations, we find no difference in worker relatedness asymmetries between female- and male-specialist colonies. Furthermore, no clear link was found between colony sex allocation and life history traits such as the number of mates per queen, or colony size, resource level, or fecundity. We also failed to find significant support for male production by workers, infection by Wolbachia, local resource competition, or local mate competition. We are left with the possibility that Allomerus exhibits split sex ratios because of the evolution of alternative biasing strategies in queens or workers, as recently proposed in the literature. [source]


    JOURNAL OF PHYCOLOGY, Issue 4 2010
    Arthur R. Grossman
    Many regions of the open, oligotrophic oceans are depleted of nutrients, especially nitrogen and iron. The biogenesis and the functioning of the photosynthetic apparatus may be specialized and tailored to the various marine habitats. In this minireview, we discuss some new findings with respect to photosynthetic processes in the oceans. We focus on findings that suggest that some cyanobacteria may route electrons derived from the splitting of H2O to the reduction of O2 and H+ in a water-to-water cycle, and that other cyanobacteria that fix nitrogen during the day are likely missing PSII and enzymes involved in the fixation of inorganic carbon. Both of these proposed "variant" forms of photosynthetic electron flow provide new insights into ways in which marine phytoplankton satisfy their energetic and nutritive requirements. [source]


    James R. Beebe
    I examine the conditions which hypotheses must satisfy if they are to be used to raise significant sceptical challenges. I argue that sceptical hypotheses do not have to be logically, metaphysically or epistemically possible: they need only to depict scenarios subjectively indistinguishable from the actual world and to show how subjects can believe what they do while not having knowledge. I also argue that sceptical challenges can be raised against a priori beliefs, even if those beliefs are necessarily true. I hope to broaden our conception of the legitimate kinds of sceptical challenges which can be raised. [source]


    ADDICTION, Issue 11 2009
    No abstract is available for this article. [source]


    EVOLUTION, Issue 8 2009
    Bryn T. M. Dentinger
    The ,50 million-year-old fungus-farming ant mutualism is a classic example of coevolution, involving ants that subsist on asexual, fungal biomass, in turn propagating the fungus clonally through nest-to-nest transmission. Most mutualistic ants cultivate two closely related groups of gilled mushrooms, whereas one small group of ants in the genus Apterostigma cultivates a distantly related lineage comprised of the G2 and G4 groups. The G2 and G4 fungi were previously shown to form a monophyletic group sister to the thread-like coral mushroom family Pterulaceae. Here, we identify an enigmatic coral mushroom that produces both fertile and sterile fruiting structures as the closest free-living relative of the G4 fungi, challenging the monophyly of the Apterostigma -cultivated fungi for the first time. Both nonparametric bootstrap and Bayesian posterior probability support the node leading to the G4 cultivars and a free-living Pterula mushroom. These data suggest three scenarios that contradict the hypothesis of strict coevolution: (1) multiple domestications, (2) escape from domestication, (3) selection of single cultivar lineages from an ancestral mixed-fungus garden. These results illustrate how incomplete phylogenies for coevolved symbionts impede our understanding of the patterns and processes of coevolution. [source]


    EVOLUTION, Issue 4 2008
    Marcel E. Dorken
    Separate sexes can evolve under nuclear inheritance when unisexuals have more than twice the reproductive fitness of hermaphrodites through one sex function (e.g., when females have more than twice the seed fertility of hermaphrodites). Because separate sexes are thought to evolve most commonly via a gynodioecious intermediate (i.e., populations in which females and hermaphrodites cooccur), the conditions under which females can become established in populations of hermaphrodites are of considerable interest. It has been proposed that resource-poor conditions could promote the establishment of females if hermaphrodites are plastic in their sex allocation and allocate fewer resources to seed production under these conditions. If this occurs, the seed fertility of females could exceed the doubling required for the evolution of unisexuality under low-, but not high-resource conditions (the sex-differential plasticity hypothesis). We tested this hypothesis using replicate experimental arrays of the aquatic herb Sagittaria latifolia grown under two fertilizer treatments. The results supported the sex-differential plasticity hypothesis, with females having more than twice the seed fertility of hermaphrodites under low-, but not high-fertilizer conditions. Our findings are consistent with the idea that separate sexes are more likely to evolve under unfavorable conditions. [source]


    EVOLUTION, Issue 10 2006
    C. D. Hulsey
    Abstract The extent to which elements of functional systems can change independently (modularity) likely influences the diversification of lineages. Major innovations in organismal design, like the pharyngeal jaw in cichlid fishes, may be key to a group's success when they relax constraints on diversification by increasing phenotypic modularity. In cichlid fishes, pharyngeal jaw modifications that enhanced the ability to breakdown prey may have freed their oral jaws from serving their ancestral dual role as a site of both prey capture and prey processing. This functional decoupling that allowed the oral jaws to become devoted solely to prey capture has been hypothesized to have permitted the two sets of cichlid jaws to evolve independently. We tested the hypothesis that oral and pharyngeal jaw mechanics are evolutionarily decoupled both within and among Neotropical Heroine cichlids. In the trophically polymorphic species Herichthys minckleyi, molariforms that exhibit enlarged molarlike pharyngeal jaw teeth were found to have approximately 400% greater lower jaw mass compared to H. minckleyi with the alternative papilliform pharyngeal morphology. However, oral jaw gape, lower jaw velocity ratios, anterior jaw linkage mechanics, and jaw protrusion did not differ between the morphotypes. In 40 other Heroine species, there was a weak correlation between oral jaw mechanics and pharyngeal jaw mass when phylogenetic history was ignored. Yet, after expansion of the cytochrome b phylogeny for Heroines, change in oral jaw mechanics was found to be independent of evolutionary change in pharyngeal jaw mass based on independent contrasts. Evolutionary decoupling of oral and pharyngeal jaw mechanics has likely played a critical role in the unparalleled trophic diversification of cichlid fishes. [source]


    EVOLUTION, Issue 5 2003
    Kathryn D. Kavanagh
    Abstract The switch between the cell cycle and the progress of differentiation in developmental pathways is prevalent throughout the eukaryotes in all major cell lineages. Disruptions to the molecular signals regulating the switch between proliferative and differentiating states are severe, often resulting in cancer formation (uncontrolled proliferation) or major developmental disorders. Uncontrolled proliferation and developmental disorders are potentially lethal defects in the developing animal. Therefore, natural selection would likely favor a tightly controlled regulatory mechanism to help prevent these fundamental defects. Although selection is usually thought of as a consequence of environmental or ecological influences, in this case the selective force to maintain this molecular switch is internal, manifested as a potentially lethal developmental defect. The morphogenetic consequences of this prevalent, deeply embedded, and tightly controlled mechanistic switch are currently unexplored, however experimental and correlative evidence from several sources suggest that there are important consequences on the control of growth rates and developmental rates in organs and in the whole animal. These observations lead one to consider the possibility of a developmental constraint on ontogenetic rates and morphological evolution maintained by natural selection against cancer and other embryonic lethal defects. [source]


    JOURNAL OF PHYCOLOGY, Issue 5 2010
    The cyanobacterial endosymbionts of Paulinella chromatophora can shed new light on the process of plastid acquisition. Their genome is devoid of many essential genes, suggesting gene transfer to the host nucleus and protein import back into the endosymbionts/plastids. Strong evidence for such gene transfer is provided by the psaE gene, which encodes a PSI component that was efficiently transferred to the Paulinella nucleus. It remains unclear, however, how this protein is imported into the endosymbionts/plastids. We reanalyzed the sequence of Paulinella psaE and identified four potential non-AUG translation initiation codons upstream of the previously proposed start codon. Interestingly, the longest polypeptide, starting from the first UUG, contains a clearly identifiable signal peptide with very high (90%) predictability. We also found several downstream hairpin structures that could enhance translation initiation from the alternative codon. These results strongly suggest that the PsaE protein is targeted to the outer membrane of Paulinella endosymbionts/plastids via the endomembrane system. On the basis of presence of respective bacterial homologs in the Paulinella endosymbiont/plastid genome, we discuss further trafficking of PsaE through the peptidoglycan wall and the inner envelope membrane. It is possible that other nuclear-encoded proteins of P. chromatophora also carry signal peptides, but, alternatively, some may be equipped with transit peptides. If this is true, Paulinella endosymbionts/plastids would possess two distinct targeting systems, one cotranslational and the second posttranslational, as has been found in higher plant plastids. Considering the endomembrane system-mediated import pathway, we also discuss homology of the membranes surrounding Paulinella endosymbionts/plastids. [source]


    JOURNAL OF PHYCOLOGY, Issue 5 2008
    M. Virginia Sanchez-Puerta
    Four eukaryotic lineages, namely, haptophytes, alveolates, cryptophytes, and heterokonts, contain in most cases photosynthetic and nonphotosynthetic members,the photosynthetic ones with secondary plastids with chl c as the main photosynthetic pigment. These four photosynthetic lineages were grouped together on the basis of their pigmentation and called chromalveolates, which is usually understood to imply loss of plastids in the nonphotosynthetic members. Despite the ecological and economic importance of this group of organisms, the phylogenetic relationships among these algae are only partially understood, and the so-called chromalveolate hypothesis is very controversial. This review evaluates the evidence for and against this grouping and summarizes the present understanding of chromalveolate evolution. We also describe a testable hypothesis that is intended to accommodate current knowledge based on plastid and nuclear genomic data, discuss the implications of this model, and comment on areas that require further examination. [source]


    JOURNAL OF PHYCOLOGY, Issue 2 2003
    Daniel Grzebyk
    Although all chloroplasts appear to have been derived from a common ancestor, a major schism occurred early in the evolution of eukaryotic algae that gave rise to red and green photoautotrophic lineages. In Paleozoic and earlier times, the fossil record suggests that oceanic eukaryotic phytoplankton were dominated by the green (chl b -containing) algal line. However, following the end-Permian extinction, a diverse group of eukaryotic phytoplankton evolved from secondary symbiotic associations in the red (chl c -containing) line and subsequently rose to ecological prominence. In the contemporary oceans, red eukaryotic phytoplankton taxa continue to dominate marine pelagic food webs, whereas the green line is relegated to comparatively minor ecological and biogeochemical roles. To help elucidate why the oceans are not dominated by green taxa, we analyzed and compared whole plastid genomes in both the red and green lineages. Our results suggest that whereas all algal plastids retain a core set of genes, red plastids retain a complementary set of genes that potentially confer more capacity to autonomously express proteins regulating oxygenic photosynthetic and energy transduction pathways. We hypothesize that specific gene losses in the primary endosymbiotic green plastid reduced its portability for subsequent symbiotic associations. This corollary of the plastid "enslavement" hypothesis may have limited subsequent evolutionary advances in the green lineage while simultaneously providing a competitive advantage to the red lineage. [source]

    HYPOTHESIS: Sjögren's syndrome: a possible pathogenetic mechanism involving somatostatin

    ORAL DISEASES, Issue 5 2000
    L Baccaglini
    Sjögren's syndrome is a chronic systemic disease that primarily affects the salivary and lacrimal glands. The pathogenesis of Sjögren's syndrome is unknown. We hypothesize that reduced somatostatin activity is an important factor in promoting immune dysregulation in patients affected by Sjögren's syndrome. Somatostatin is a multifunctional peptide with potent immunomodulatory properties. Its effects include reduced lymphocytic activity, reduced gastric and intestinal secretions, activation of the hypothalamic-pituitary axis, and anti-inflammatory action, all opposite to the general presentation in Sjögren's syndrome. We suggest that the activity of somatostatin is low in patients affected by this disease, and this contributes significantly to the pathology observed. [source]


    This paper examines the export-led growth (ELG) hypothesis for five South Asian countries through cointegration and multivariate Granger causality tests. Strong support for a long-run relationship among exports, imports, and real output for all the countries except Sri Lanka were found. Feedback effects between exports and GDP for Bangladesh and Nepal and unidirectional causality from exports to output in the case of Pakistan were found. No causality between these variables was found for Sri Lanka and India, although for India GDP and exports did induce imports. A feedback effect between imports and GDP was also documented for Pakistan, Bangladesh, and Nepal, as well as unidirectional causality from imports to output growth for Sri Lanka. These and other findings are discussed from the standpoint of the export-led growth hypothesis. [source]


    Kam C. Chan
    Abstract We investigate net buying pressure in the Hong Kong Hang Seng Index options market during the Asian financial crisis from July 1997 to August 1998. Our findings suggest that during this period, the dramatic changes in volatility overwhelmed the dynamics of supply and demand in the options market. The extremely high realized volatility drove market participants' expectations about future market volatility in the early months of the crisis. Findings during the late-crisis, pre-crisis, and post-crisis periods are consistent with the net buying pressure hypothesis. [source]


    David L Morgan
    SUMMARY 1.,Exercise that involves stretching a muscle while active cause microscopic areas of damage, delayed onset muscle soreness and adaptation to withstand subsequent similar exercise. 2.,Longer muscle lengths are associated with greater damage and recent animal experiments show that it is the length relative to optimum that determines the damage. 3.,In humans, walking down stairs, taking two at a time, increases the length of the muscle during the lengthening and increases the delayed onset muscle soreness. 4.,The observed pattern of damage is consistent with explanations based on sarcomere length instabilities. 5.,The pattern of adaptation is consistent with the number of sarcomeres in series in a muscle being modulated by exercise, especially the range of muscle lengths over which eccentric exercise regularly occurs. [source]

    Spatial Tests of the Pesticide Drift, Habitat Destruction, UV-B, and Climate-Change Hypotheses for California Amphibian Declines

    Carlos Davidson
    In California, the transport and deposition of pesticides from the agriculturally intensive Central Valley to the adjacent Sierra Nevada is well documented, and pesticides have been found in the bodies of Sierra frogs. Pesticides are therefore a plausible cause of declines, but to date no direct links have been found between pesticides and actual amphibian population declines. Using a geographic information system, we constructed maps of the spatial pattern of declines for eight declining California amphibian taxa, and compared the observed patterns of decline to those predicted by hypotheses of wind-borne pesticides, habitat destruction, ultraviolet radiation, and climate change. In four species, we found a strong positive association between declines and the amount of upwind agricultural land use, suggesting that wind-borne pesticides may be an important factor in declines. For two other species, declines were strongly associated with local urban and agricultural land use, consistent with the habitat-destruction hypothesis. The patterns of decline were not consistent with either the ultraviolet radiation or climate-change hypotheses for any of the species we examined. Resumen: Por mucho tiempo se ha sugerido que los pesticidas transportados por el viento son una causa de la declinación de anfibios en áreas sin destrucción de hábitat evidente. En California, el transporte y depósito de pesticidas provenientes del Valle Central, donde se practica la agricultura intensiva, hacia la Sierra Nevada adyacente está bien documentado y se han encontrado pesticidas en el cuerpo de ranas de la Sierra. Por lo tanto, los pesticidas son una causa verosímil de las declinaciones, pero a la fecha no se han encontrado relaciones directas entre los pesticidas y la declinación de anfibios. Construimos mapas de sistemas de información geográfica del patrón espacial de las declinaciones de ocho taxones de anfibios de California, y comparamos los patrones de declinación observados con los esperados por las hipótesis de pesticidas transportados por el viento, la destrucción del hábitat, la radiación ultravioleta y el cambio climático. En cuatro especies, encontramos una fuerte asociación positiva entre las declinaciones y la cantidad de tierras de uso agrícola en dirección contraria a los vientos, lo que sugiere que los pesticidas transportados por el viento pueden ser un factor importante en las declinaciones. Para otras dos especies, las declinaciones se asociaron contundentemente con el uso del suelo urbano y agrícola, lo cual es consistente con la hipótesis de la destrucción del hábitat. Los patrones de declinación no fueron consistentes con la hipótesis de la radiación ultravioleta ni la de cambio climático para ninguna de las especies examinadas. [source]

    Developing an attitude towards bullying scale for prisoners: structural analyses across adult men, young adults and women prisoners

    Jane L. Ireland
    Background,Few studies have attempted to explore attitudes towards bullying among prisoners, despite acknowledgement that attitudes may play an important role. Aim,To evaluate the structure of a new attitudinal scale, the Prison Bullying Scale (PBS), with adult men and women in prison and with young male prisoners. Hypotheses,That attitudes would be represented as a multidimensional construct and that the PBS structure would be replicated across confirmatory samples. Method,The PBS was developed and confirmed across four independent studies using item parceling and confirmatory factor analysis: Study I comprised 412 adult male prisoners; Study II, 306 adult male prisoners; Study III, 171 male young offenders; and Study IV, 148 adult women prisoners. Results,Attitudes were represented as a multidimensional construct comprising seven core factors. The exploratory analysis was confirmed in adult male samples, with some confirmation among young offenders and adult women. The fit for young offenders was adequate and improved by factor covariance. The fit for women was the poorest overall. Conclusion,The study notes the importance of developing ecologically valid measures and statistically testing these measures prior to their clinical or research use. Implications,The development of the PBS holds value both as an assessment and as a research measure and remains the only ecologically validated measure in existence to assess prisoner attitudes towards bullying. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    The Decision of the Supply Chain Executive to Support or Impede Supply Chain Integration: A Multidisciplinary Behavioral Agency Perspective,

    DECISION SCIENCES, Issue 4 2009
    Verónica H. Villena
    ABSTRACT Applying the behavioral agency model developed by Wiseman and Gomez-Mejia (1998), this article analyzes human resource factors that induce supply chain executives (SCEs) to make decisions that foster or hinder supply chain integration. We examine two internal sources (compensation and employment risk) and one external source (environmental volatility) of risk bearing that can make SCEs more reluctant to make the decision to promote supply chain integration. We argue and empirically confirm the notion that an employment and compensation system that increases SCE risk bearing reduces the SCE's willingness to make risky decisions and thus discourages supply chain integration. We also reveal that this negative relationship becomes stronger under conditions of high environmental volatility. In addressing the "so what?" question, we found empirical support for the hypothesis that supply chain integration positively influences operational performance. Even though this decision has a positive value for the firm, we showed that SCEs discourage supply chain integration when they face higher risk bearing. Hypotheses are tested using a combination of primary survey data and archival measures in a sample of 133 Spanish firms. [source]

    Supply Management Under High Goal Incongruence: An Empirical Examination of Disintermediation in the Aerospace Supply Chain

    DECISION SCIENCES, Issue 3 2008
    Christian L. Rossetti
    ABSTRACT Aftermarket sales and profits are becoming an increasingly important part of an original equipment manufacturer's (OEM) business model. Because replacement parts often do not require further manufacturing, OEMs act as intermediaries in the aftermarket. As with any intermediary, the OEM must concern itself with suppliers disintermediating its supply chain selling replacement parts directly to the OEM's customers. We frame supply chain disintermediation (SCD) as a principal,agent contracting problem between an OEM buyer and a supplier. Hypotheses relate contract conditions, goal incongruence, supplier capabilities and contract enforcement to SCD. The data are collected from the aerospace industry using a multimethod study, combining an Internet-based survey with archival data. Causal modeling with structural equation modeling (SEM) shows general support for the hypotheses. Particularly, SCD is positively related to buyer,supplier goal incongruence. The agency model offers insights that differ from previous transaction-cost-based models of buyer,supplier relationships. OEM buyers with a lucrative aftermarket should consider aligning goals through incentives rather than relying entirely on economic hostages associated with specific assets. [source]

    The Dark Side of Information and Market Efficiency in E-Markets,

    DECISION SCIENCES, Issue 3 2006
    Varun Grover
    ABSTRACT Price dispersion reflects the differences in prices for identical products. While in physical markets such dispersion is prevalent due to high search costs, many researchers argue that search costs and price dispersion will be much lower in electronic markets (e-markets). Empirical evidence does not support this contention, and researchers have studied search costs, market factors, and service-quality factors to explain this dispersion. Previous research has largely assumed that more information is better. By ignoring the dark side of information, we argue that only a partial understanding of price dispersion is possible. In this article, information overload and equivocality are studied as two dark attributes of information that lead sellers to different pricing decisions in e-markets. Hypotheses relating these attributes to price dispersion are supported through analysis of 161 product markets. This work opens up new avenues in the study of e-markets and discusses the implications of these findings for research and practice on consumer and seller decisions. [source]

    Technology-Based New Product Development Partnerships,

    DECISION SCIENCES, Issue 2 2006
    John E. Ettlie
    ABSTRACT Hypotheses were developed to capture the dynamic capabilities that result from interfirm partnerships during the joint new product development (NPD) process,the ability to build, integrate, and reconfigure existing resources to adapt to rapidly changing environments. These capabilities, in turn, were proposed to have a positive impact on NPD performance outcomes: (a) proportion of new product success and (b) superior new product commercialization. In contexts where the locus of innovation is rapidly changing, the impact of interfirm NPD dynamic capabilities was hypothesized to be diminished in high-technology contexts, especially for buyers (original equipment manufacturers) and to a lesser extent for suppliers. Still, technology-based interfirm NPD partnerships were predicted to ultimately outperform low-technology ones in both NPD performance outcomes. Finally, information technology (IT) support for NPD was hypothesized to influence the interfirm NPD partnership's dynamic capabilities. Using survey data from 72 auto company managers and their suppliers, the proposed model in which IT support for NPD influences the success of interfirm NPD partnerships through the mediating role of interfirm NPD partnership dynamic capabilities in high- and low-technology contexts was generally supported. The results shed light on the nature of technology-based interfirm NPD partnerships and have implications for their success. Theoretical and managerial implications are discussed. [source]

    Manufacturing Practices and Strategy Integration: Effects on Cost Efficiency, Flexibility, and Market-Based Performance

    DECISION SCIENCES, Issue 3 2005
    Morgan Swink
    ABSTRACT Manufacturing plant managers have sought performance improvements through implementing best practices discussed in World Class Manufacturing literature. However, our collective understanding of linkages between practices and performance remains incomplete. This study seeks a more complete theory, advancing the idea that strategy integration and enhanced manufacturing capabilities such as cost efficiency and flexibility serve as intermediaries by which practices affect performance. Hypotheses related to this thesis are tested using data from 57 North American manufacturing plants that are past winners and finalists in Industry Week's"America's Best" competition (Drickhamer, 2001). The results suggest that strategy integration plays a strong, central role in the creation of manufacturing cost efficiency and new product flexibility capabilities. Furthermore, strategy integration moderates the influences of product-process development, supplier relationship management, workforce development, just-in-time flow, and process quality management practices on certain manufacturing capabilities. In turn, manufacturing cost efficiency and new product flexibility capabilities mediate the influence of strategy integration on market-based performance. These findings have implications for practice and for future research. [source]

    Rhabdomyolysis and brain ischemic stroke in a heroin-dependent male under methadone maintenance therapy

    W.-Y. Hsu
    Objective:, There are several complications associated with heroin abuse, some of which are life-threatening. Methadone may aggravate this problem. Method:, A clinical case description. Results:, A 33-year-old man presented with rhabdomyolysis and cerebral ischemic stroke after intravenous heroin. He had used heroin since age 20, and had used 150 mg methadone daily for 6 months. He was found unconsciousness at home and was sent to our hospital. In the ER, his opiate level was 4497 ng/ml. In the ICU, we found rhabdomyolysis, acute renal failure and acute respiratory failure. After transfer to an internal ward, we noted aphasia and weakness of his left limbs. After MRI, we found cerebral ischemic infarction. Conclusion:, Those using methadone and heroin simultaneously may increase risk of rhabdomyolysis and ischemic stroke. Patients under methadone maintenance therapy should be warned regarding these serious adverse events. Hypotheses of heroin-related rhabdomyolysis and stroke in heroin abusers are discussed. [source]

    A role for innate immunity in type 1 diabetes?

    H. Beyan
    Abstract Two arms of the immune system, innate and adaptive immunity, differ in their mode of immune recognition. The innate immune system recognizes a few highly conserved structures on a broad range of microorganisms. On the other hand, recognition of self or autoreactivity is generally confined to the adaptive immune response. Whilst autoimmune features are relatively common, they should be distinguished from autoimmune disease that is infrequent. Type 1 diabetes is an immune-mediated disease due to the destruction of insulin secreting cells mediated by aggressive immune responses, including activation of the adaptive immune system following genetic and environmental interaction. Hypotheses for the cause of the immune dysfunction leading to type 1 diabetes include self-reactive T-cell clones that (1) escape deletion in the thymus, (2) escape from peripheral tolerance or (3) escape from homeostatic control with an alteration in the immune balance leading to autoimmunity. Evidence, outlined in this review, raises the possibility that changes in the innate immune system could lead to autoimmunity, by either priming or promoting aggressive adaptive immune responses. Hostile microorganisms are identified by genetically determined surface receptors on innate effector cells, thereby promoting clearance of these invaders. These innate effectors include a few relatively inflexible cell populations such as monocytes/macrophages, dendritic cells (DC), natural killer (NK) cells, natural killer T (NKT) cells and ,, T cells. Recent studies have identified abnormalities in some of these cells both in patients with type 1 diabetes and in those at risk of the disease. However, it remains unclear whether these abnormalities in innate effector cells predispose to autoimmune disease. If they were to do so, then modulation of the innate immune system could be of therapeutic value in preventing immune-mediated diseases such as type 1 diabetes. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    Minireview: On the homology of the protocoel in Cephalochordata and ,lower' Deuterostomia

    ACTA ZOOLOGICA, Issue 1 2002
    Thomas Stach
    Abstract Hypotheses regarding the homology of the protocoel in planktonic deuterostome larvae and mesodermal structures in ontogenetic stages of cephalochordates are evaluated. The prevalent ,classical' hypothesis describes the protocoel as being homologous with the diverticula of Hatschek, which, on the left side, develop into the preoral pit, subsequently into Hatschek's pit and groove (in part). This hypothesis is based mainly on the position of Hatschek's diverticula anterior to the rest of the mesoderm during their enterocoelic origin. It is shown here that during development the mesodermal segment that develops into Hatschek's nephridium is the most anterior one prior to formation of Hatschek's diverticula, and this segment assumes an anteriormost position after differentiation of Hatschek's diverticula. Additional similarities between this segment and protocoels are: (i) presence of endomesodermal cells with podocytic extensions, (ii) excretory function, (iii) relatively early ontogenetic origin, (iv) probable lack of association with nervous structures, (v) probable ectodermal origin of a portion of the canal, and (vi) position relative to the mouth opening. Therefore, homology between the protocoel and the segment that becomes Hatschek's nephridium is proposed. It is concluded that a glandular structure homologous to the diverticula of Hatschek and anterior to the protocoel/Hatschek's nephridium is a synapomorphy of notochordates or chordates. [source]