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Sample records for ability eica hypothesis

  1. Evaluation of the evolution of increased competitive ability (EICA) hypothesis: loss of defense against generalist but not specialist herbivores.

    PubMed

    Hull-Sanders, Helen M; Clare, Robert; Johnson, Robert H; Meyer, Gretchen A

    2007-04-01

    The evolution of increased competitive ability (EICA) hypothesis predicts that invasive plant species may escape their specialized natural enemies in their introduced range and subsequently evolve with a decrease in investment in anti-herbivore chemical defenses relative to native conspecifics. We compared the chemical profile of 10 populations of US native and 20 populations of European invasive Solidago gigantea. To test for differences in inducibility between native and invasive populations, we measured secondary chemistry in both damaged and undamaged plants. We also performed bioassays with three specialist and two generalist insect herbivores from four different feeding guilds. There was no evidence that invasive populations had reduced concentrations of sesquiterpenes, diterpenes, or short-chain hydrocarbons (SCH), although significant variation among populations was detected. Sesquiterpene and diterpene concentrations were not influenced by damage to the host plant, whereas SCH concentrations were decreased by damage for both native and invasive plants. Performance of the three specialist insects was not affected by the continental origin of the host plant. However, larval mass of the generalist caterpillar Spodoptera exigua was 37% lower on native plants compared to invasive plants. The other generalist insect, a xylem-tapping spittlebug that occurs on both continents, performed equally well on native and invasive plants. These results offer partial support for the defense predictions of the EICA hypothesis: the better growth of Spodoptera caterpillars on European plants shows that some defenses have been lost in the introduced range, even though our measures of secondary chemistry did not detect differences between continents. Our results show significant variation in chemical defenses and herbivore performance across populations on both continents and emphasize the need for analysis across a broad spatial scale and the use of multiple herbivores. PMID

  2. Meta-analysis reveals evolution in invasive plant species but little support for Evolution of Increased Competitive Ability (EICA)

    PubMed Central

    Felker-Quinn, Emmi; Schweitzer, Jennifer A; Bailey, Joseph K

    2013-01-01

    Ecological explanations for the success and persistence of invasive species vastly outnumber evolutionary hypotheses, yet evolution is a fundamental process in the success of any species. The Evolution of Increased Competitive Ability (EICA) hypothesis (Blossey and Nötzold 1995) proposes that evolutionary change in response to release from coevolved herbivores is responsible for the success of many invasive plant species. Studies that evaluate this hypothesis have used different approaches to test whether invasive populations allocate fewer resources to defense and more to growth and competitive ability than do source populations, with mixed results. We conducted a meta-analysis of experimental tests of evolutionary change in the context of EICA. In contrast to previous reviews, there was no support across invasive species for EICA's predictions regarding defense or competitive ability, although invasive populations were more productive than conspecific native populations under noncompetitive conditions. We found broad support for genetically based changes in defense and competitive plant traits after introduction into new ranges, but not in the manner suggested by EICA. This review suggests that evolution occurs as a result of plant introduction and population expansion in invasive plant species, and may contribute to the invasiveness and persistence of some introduced species. PMID:23531703

  3. A Test of the EICA hypothesis using French broom (Genista monspessulana)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several hypotheses have been proposed to account for the success of non-indigenous plant species in their introduced range. The EICA hypothesis proposes that the low abundance or absence of herbivores in new environments may drive selection for genotypes with increased allocation to growth and repr...

  4. No evolution of increased competitive ability or decreased allocation to defense in Melaleuca quinquenervia since release from natural enemies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    If invasive plants are released from natural enemies in their introduced range, they may evolve decreased allocation to defense and increased growth, as predicted by the evolution of increased competitive ability (EICA) hypothesis. A field experiment using the invasive tree Melaleuca quinquenervia ...

  5. No difference in the competitive ability of introduced and native Trifolium provenances when grown with soil biota from their introduced and native ranges

    PubMed Central

    Shelby, Natasha; Hulme, Philip E.; van der Putten, Wim H.; McGinn, Kevin J.; Weser, Carolin; Duncan, Richard P.

    2016-01-01

    The evolution of increased competitive ability (EICA) hypothesis could explain why some introduced plant species perform better outside their native ranges. The EICA hypothesis proposes that introduced plants escape specialist pathogens or herbivores leading to selection for resources to be reallocated away from defence and towards greater competitive ability. We tested the hypothesis that escape from soil-borne enemies has led to increased competitive ability in three non-agricultural Trifolium (Fabaceae) species native to Europe that were introduced to New Zealand in the 19th century. Trifolium performance is intimately tied to rhizosphere biota. Thus, we grew plants from one introduced (New Zealand) and two native (Spain and the UK) provenances for each of three species in pots inoculated with soil microbiota collected from the rhizosphere beneath conspecifics in the introduced and native ranges. Plants were grown singly and in competition with conspecifics from a different provenance in order to compare competitive ability in the presence of different microbial communities. In contrast to the predictions of the EICA hypothesis, we found no difference in the competitive ability of introduced and native provenances when grown with soil microbiota from either the native or introduced range. Although plants from introduced provenances of two species grew more slowly than native provenances in native-range soils, as predicted by the EICA hypothesis, plants from the introduced provenance were no less competitive than native conspecifics. Overall, the growth rate of plants grown singly was a poor predictor of their competitive ability, highlighting the importance of directly quantifying plant performance in competitive scenarios, rather than relying on surrogate measures such as growth rate. PMID:26969431

  6. No difference in the competitive ability of introduced and native Trifolium provenances when grown with soil biota from their introduced and native ranges.

    PubMed

    Shelby, Natasha; Hulme, Philip E; van der Putten, Wim H; McGinn, Kevin J; Weser, Carolin; Duncan, Richard P

    2016-01-01

    The evolution of increased competitive ability (EICA) hypothesis could explain why some introduced plant species perform better outside their native ranges. The EICA hypothesis proposes that introduced plants escape specialist pathogens or herbivores leading to selection for resources to be reallocated away from defence and towards greater competitive ability. We tested the hypothesis that escape from soil-borne enemies has led to increased competitive ability in three non-agriculturalTrifolium(Fabaceae) species native to Europe that were introduced to New Zealand in the 19th century.Trifoliumperformance is intimately tied to rhizosphere biota. Thus, we grew plants from one introduced (New Zealand) and two native (Spain and the UK) provenances for each of three species in pots inoculated with soil microbiota collected from the rhizosphere beneath conspecifics in the introduced and native ranges. Plants were grown singly and in competition with conspecifics from a different provenance in order to compare competitive ability in the presence of different microbial communities. In contrast to the predictions of the EICA hypothesis, we found no difference in the competitive ability of introduced and native provenances when grown with soil microbiota from either the native or introduced range. Although plants from introduced provenances of two species grew more slowly than native provenances in native-range soils, as predicted by the EICA hypothesis, plants from the introduced provenance were no less competitive than native conspecifics. Overall, the growth rate of plants grown singly was a poor predictor of their competitive ability, highlighting the importance of directly quantifying plant performance in competitive scenarios, rather than relying on surrogate measures such as growth rate. PMID:26969431

  7. Memory Abilities in Williams Syndrome: Dissociation or Developmental Delay Hypothesis?

    ERIC Educational Resources Information Center

    Sampaio, Adriana; Sousa, Nuno; Fernandez, Montse; Henriques, Margarida; Goncalves, Oscar F.

    2008-01-01

    Williams syndrome (WS) is a neurodevelopmental genetic disorder often described as being characterized by a dissociative cognitive architecture, in which profound impairments of visuo-spatial cognition contrast with relative preservation of linguistic, face recognition and auditory short-memory abilities. This asymmetric and dissociative cognition…

  8. A comprehensive test of evolutionarily increased competitive ability in a highly invasive plant species

    PubMed Central

    Joshi, Srijana; Gruntman, Michal; Bilton, Mark; Seifan, Merav; Tielbörger, Katja

    2014-01-01

    Background and Aims A common hypothesis to explain plants' invasive success is that release from natural enemies in the introduced range selects for reduced allocation to resistance traits and a subsequent increase in resources available for growth and competitive ability (evolution of increased competitive ability, EICA). However, studies that have investigated this hypothesis have been incomplete as they either did not test for all aspects of competitive ability or did not select appropriate competitors. Methods Here, the prediction of increased competitive ability was examined with the invasive plant Lythrum salicaria (purple loosestrife) in a set of common-garden experiments that addressed these aspects by carefully distinguishing between competitive effect and response of invasive and native plants, and by using both intraspecific and interspecific competition settings with a highly vigorous neighbour, Urtica dioica (stinging nettle), which occurs in both ranges. Key Results While the intraspecific competition results showed no differences in competitive effect or response between native and invasive plants, the interspecific competition experiment revealed greater competitive response and effect of invasive plants in both biomass and seed production. Conclusions The use of both intra- and interspecific competition experiments in this study revealed opposing results. While the first experiment refutes the EICA hypothesis, the second shows strong support for it, suggesting evolutionarily increased competitive ability in invasive populations of L. salicaria. It is suggested that the use of naturally co-occurring heterospecifics, rather than conspecifics, may provide a better evaluation of the possible evolutionary shift towards greater competitive ability. PMID:25301818

  9. Mental Abilities and School Achievement: A Test of a Mediation Hypothesis

    ERIC Educational Resources Information Center

    Vock, Miriam; Preckel, Franzis; Holling, Heinz

    2011-01-01

    This study analyzes the interplay of four cognitive abilities--reasoning, divergent thinking, mental speed, and short-term memory--and their impact on academic achievement in school in a sample of adolescents in grades seven to 10 (N = 1135). Based on information processing approaches to intelligence, we tested a mediation hypothesis, which states…

  10. Integrating novel chemical weapons and evolutionarily increased competitive ability in success of a tropical invader.

    PubMed

    Zheng, Yu-Long; Feng, Yu-Long; Zhang, Li-Kun; Callaway, Ragan M; Valiente-Banuet, Alfonso; Luo, Du-Qiang; Liao, Zhi-Yong; Lei, Yan-Bao; Barclay, Gregor F; Silva-Pereyra, Carlos

    2015-02-01

    The evolution of increased competitive ability (EICA) hypothesis and the novel weapons hypothesis (NWH) are two non-mutually exclusive mechanisms for exotic plant invasions, but few studies have simultaneously tested these hypotheses. Here we aimed to integrate them in the context of Chromolaena odorata invasion. We conducted two common garden experiments in order to test the EICA hypothesis, and two laboratory experiments in order to test the NWH. In common conditions, C. odorata plants from the nonnative range were better competitors but not larger than plants from the native range, either with or without the experimental manipulation of consumers. Chromolaena odorata plants from the nonnative range were more poorly defended against aboveground herbivores but better defended against soil-borne enemies. Chromolaena odorata plants from the nonnative range produced more odoratin (Eupatorium) (a unique compound of C. odorata with both allelopathic and defensive activities) and elicited stronger allelopathic effects on species native to China, the nonnative range of the invader, than on natives of Mexico, the native range of the invader. Our results suggest that invasive plants may evolve increased competitive ability after being introduced by increasing the production of novel allelochemicals, potentially in response to naïve competitors and new enemy regimes. PMID:25367824

  11. The Interaction between Root Herbivory and Competitive Ability of Native and Invasive-Range Populations of Brassica nigra.

    PubMed

    Oduor, Ayub M O; Stift, Marc; van Kleunen, Mark

    2015-01-01

    The evolution of increased competitive ability (EICA) hypothesis predicts that escape from intense herbivore damage may enable invasive plants to evolve higher competitive ability in the invasive range. Below-ground root herbivory can have a strong impact on plant performance, and invasive plants often compete with multiple species simultaneously, but experimental approaches in which EICA predictions are tested with root herbivores and in a community setting are rare. Here, we used Brassica nigra plants from eight invasive- and seven native-range populations to test whether the invasive-range plants have evolved increased competitive ability when competing with Achillea millefolium and with a community (both with and without A. millefolium). Further, we tested whether competitive interactions depend on root herbivory on B. nigra by the specialist Delia radicum. Without the community, competition with A. millefolium reduced biomass of invasive- but not of native-range B. nigra. With the community, invasive-range B. nigra suffered less than native-range B. nigra. Although the overall effect of root herbivory was not significant, it reduced the negative effect of the presence of the community. The community produced significantly less biomass when competing with B. nigra, irrespective of the range of origin, and independent of the presence of A. millefolium. Taken together, these results offer no clear support for the EICA hypothesis. While native-range B. nigra plants appear to be better in dealing with a single competitor, the invasive-range plants appear to be better in dealing with a more realistic multi-species community. Possibly, this ability of tolerating multiple competitors simultaneously has contributed to the invasion success of B. nigra in North America. PMID:26517125

  12. The Interaction between Root Herbivory and Competitive Ability of Native and Invasive-Range Populations of Brassica nigra

    PubMed Central

    Oduor, Ayub M. O.; Stift, Marc; van Kleunen, Mark

    2015-01-01

    The evolution of increased competitive ability (EICA) hypothesis predicts that escape from intense herbivore damage may enable invasive plants to evolve higher competitive ability in the invasive range. Below-ground root herbivory can have a strong impact on plant performance, and invasive plants often compete with multiple species simultaneously, but experimental approaches in which EICA predictions are tested with root herbivores and in a community setting are rare. Here, we used Brassica nigra plants from eight invasive- and seven native-range populations to test whether the invasive-range plants have evolved increased competitive ability when competing with Achillea millefolium and with a community (both with and without A. millefolium). Further, we tested whether competitive interactions depend on root herbivory on B. nigra by the specialist Delia radicum. Without the community, competition with A. millefolium reduced biomass of invasive- but not of native-range B. nigra. With the community, invasive-range B. nigra suffered less than native-range B. nigra. Although the overall effect of root herbivory was not significant, it reduced the negative effect of the presence of the community. The community produced significantly less biomass when competing with B. nigra, irrespective of the range of origin, and independent of the presence of A. millefolium. Taken together, these results offer no clear support for the EICA hypothesis. While native-range B. nigra plants appear to be better in dealing with a single competitor, the invasive-range plants appear to be better in dealing with a more realistic multi-species community. Possibly, this ability of tolerating multiple competitors simultaneously has contributed to the invasion success of B. nigra in North America. PMID:26517125

  13. Failure to support the right-shift theory's hypothesis of a 'heterozygote advantage' for cognitive abilities.

    PubMed

    Cerone, L J; McKeever, W F

    1999-02-01

    Annett's (1985) 'right-shift' theory of language dominance and handedness posits three genotypes, rs++, rs(+)- and rs(-)-, and Annett has hypothesized that there are cognitive ability correlates of these genotypes. The rs++ genotype person is held to be 'at risk' for maldevelopment of spatial or other right hemisphere-based cognitive abilities, and the rs(-)- genotype individual is held to be at risk for maldevelopment of phonological abilities. Noting that there must be some adaptive advantage conferred by the heterozygous genotype for it to have survived over a presumably long period of evolution, Annett has hypothesized that heterozygotes are afforded an adaptive advantage over homozygotes because of their freedom from 'risks' to intelligence generally. Annett and colleagues have used two different indices, or markers, from which they have inferred differing concentrations of the three genotypes within groups of participants. One marker, based on responses to hand preference items of the Annett Handedness Inventory, was found by Annett (1992) to support her theory in that the least dextral of right-handed participants did best on spatial tests. The other marker Annett has used is based on the degree of right-hand advantage on a simple peg moving speed task. The present study utilized both methods and studied the performances of 259 dextral college men and women on two tests of mental rotation ability and two tests of verbal abilities. Results were not supportive of the heterozygote advantage hypothesis, and suggested that visuospatial ability was modestly related to greater dextrality of participants. PMID:10085549

  14. The evolution of increased competitive ability, innate competitive advantages, and novel biochemical weapons act in concert for a tropical invader.

    PubMed

    Qin, Rui-Min; Zheng, Yu-Long; Valiente-Banuet, Alfonso; Callaway, Ragan M; Barclay, Gregor F; Pereyra, Carlos Silva; Feng, Yu-Long

    2013-02-01

    There are many non-mutually exclusive mechanisms for exotic invasions but few studies have concurrently tested more than one hypothesis for the same species. Here, we tested the evolution of increased competitive ability (EICA) hypothesis in two common garden experiments in which Chromolaena odorata plants originating from native and nonnative ranges were grown in competition with natives from each range, and the novel weapons hypothesis in laboratory experiments with leachates from C. odorata. Compared with conspecifics originating from the native range, C. odorata plants from the nonnative range were stronger competitors at high nutrient concentrations in the nonnative range in China and experienced far more herbivore damage in the native range in Mexico. In both China and Mexico, C. odorata was more suppressed by species native to Mexico than by species native to China. Species native to China were much more inhibited by leaf extracts from C. odorata than species from Mexico, and this difference in allelopathic effects may provide a possible explanation for the biogeographic differences in competitive ability. Our results indicate that EICA, innate competitive advantages, and novel biochemical weapons may act in concert to promote invasion by C. odorata, and emphasize the importance of exploring multiple, non-mutually exclusive mechanisms for invasions. PMID:23252450

  15. The Importance of Sound for Cognitive Sequencing Abilities: The Auditory Scaffolding Hypothesis

    PubMed Central

    Conway, Christopher M.; Pisoni, David B.; Kronenberger, William G.

    2010-01-01

    Sound is inherently a temporal and sequential signal. Experience with sound therefore may help bootstrap – i.e., provide a kind of “scaffolding” for – the development of general cognitive abilities related to representing temporal or sequential patterns. Accordingly, the absence of sound early in development may result in disturbances to these sequencing skills. In support of this hypothesis we present two types of findings. First, normal-hearing adults do best on sequencing tasks when the sense of hearing, rather than vision, can be used. Second, recent findings suggest that deaf children have disturbances on exactly these same kinds of tasks that involve learning and manipulation of serial order information. We suggest that sound provides an “auditory scaffolding” for time and serial order behavior, possibly mediated through neural connections between the temporal and frontal lobes of the brain. Under conditions of auditory deprivation, auditory scaffolding is absent, resulting in neural reorganization and a disturbance to cognitive sequencing abilities. PMID:20725604

  16. Cation dyshomeostasis and cardiomyocyte necrosis: the Fleckenstein hypothesis revisited

    PubMed Central

    Borkowski, Brian J.; Cheema, Yaser; Shahbaz, Atta U.; Bhattacharya, Syamal K.; Weber, Karl T.

    2011-01-01

    An ongoing loss of cardiomyocytes to apoptotic and necrotic cell death pathways contributes to the progressive nature of heart failure. The pathophysiological origins of necrotic cell loss relate to the neurohormonal activation that accompanies acute and chronic stressor states and which includes effector hormones of the adrenergic nervous system. Fifty years ago, Albrecht Fleckenstein and coworkers hypothesized the hyperadrenergic state, which accompanies such stressors, causes cardiomyocyte necrosis based on catecholamine-initiated excessive intracellular Ca2+ accumulation (EICA), and mitochondrial Ca2+ overloading in particular, in which the ensuing dysfunction and structural degeneration of these organelles leads to necrosis. In recent years, two downstream factors have been identified which, together with EICA, constitute a signal–transducer–effector pathway: (i) mitochondria-based induction of oxidative stress, in which the rate of reactive oxygen metabolite generation exceeds their rate of detoxification by endogenous antioxidant defences; and (ii) the opening of the mitochondrial inner membrane permeability transition pore (mPTP) followed by organellar swelling and degeneration. The pathogenesis of stress-related cardiomyopathy syndromes is likely related to this pathway. Other factors which can account for cytotoxicity in stressor states include: hypokalaemia; ionized hypocalcaemia and hypomagnesaemia with resultant elevations in parathyroid hormone serving as a potent mediator of EICA; and hypozincaemia with hyposelenaemia, which compromise antioxidant defences. Herein, we revisit the Fleckenstein hypothesis of EICA in leading to cardiomyocyte necrosis and the central role played by mitochondria. PMID:21398641

  17. Left-Handedness and Spatial Reasoning Abilities: The Deficit Hypothesis Revisited.

    ERIC Educational Resources Information Center

    And Others; Gregory, R. J.

    1980-01-01

    Left-handers with an inverted handwriting posture were compared with other left-handers and with right-handers on a spatial reasoning test. Results were consistent with the hypothesis that left-inverted subjects had relatively bilateral representation of verbal and spatial functions. Bilateral representation is assumed to be inefficient.…

  18. L2 Reading Ability: Further Insight into the Short-Circuit Hypothesis.

    ERIC Educational Resources Information Center

    Taillefer, Gail F.

    1996-01-01

    Discusses the notion of a language proficiency threshold that short circuits the transfer of reading ability from the native language (L1) to a second language (L2). This study, in which cognitive complexity of tasks and students' L2 proficiency levels vary, focuses on university students in France reading preprofessional English texts. (39…

  19. Eco-immunology and bioinvasion: revisiting the evolution of increased competitive ability hypotheses.

    PubMed

    Cornet, Stéphane; Brouat, Carine; Diagne, Christophe; Charbonnel, Nathalie

    2016-09-01

    Immunity is at the core of major theories related to invasion biology. Among them, the evolution of increased competitive ability (EICA) and EICA-refined hypotheses have been used as a reference work. They postulate that the release from pathogens often experienced during invasion should favour a reallocation of resources from (costly) immune defences to beneficial life-history traits associated with invasive potential. We review studies documenting immune changes during animal invasions. We describe the designs and approaches that have been applied and discuss some reasons that prevent drawing generalized conclusions regarding EICA hypotheses. We detail why a better assessment of invasion history and immune costs, including immunopathologies and parasite communities, could improve our understanding of the relationships between immunity and invasion success. Finally, we propose new perspectives to revisit the EICA hypotheses. We first emphasize the neutral and adaptive mechanisms involved in immune changes, as well as timing of the later. Such investigation will help decipher whether immune changes are a consequence of pre-adaptation, or the result of postintroduction adaptations to invasion front conditions. We next bring attention to new avenues of research that remain unexplored, namely age-dependent immunity and gut microbiota, potential key factors underlying adaptation to invasion front environment and modulating invasion success. PMID:27606004

  20. The Hardening Hypothesis: Is the Ability to Quit Decreasing Due to Increasing Nicotine Dependence? A Review and Commentary

    PubMed Central

    Hughes, John R.

    2011-01-01

    The “hardening hypothesis” states tobacco control activities have mostly influenced those smokers who found it easier to quit and, thus, remaining smokers are those who are less likely to stop smoking. This paper first describes a conceptual model for hardening. Then the paper describes important methodological distinctions (quit attempts vs. ability to remain abstinent as indicators, measures of hardening per se vs. measures of causes of hardening, and dependence measures that do vs. do not include cigarettes per day (cigs/day).) After this commentary, the paper reviews data from prior reviews and new searches for studies on one type of hardening: the decreasing ability to quit due to increasing nicotine dependence. Overall, all four studies of the general population of smokers found no evidence of decreased ability to quit; however, both secondary analyses of treatment-seeking smokers found quit rates were decreasing over time. Cigs/day and time-to-first cigarette measures of dependence did not increase over time; however, two studies found that DSM-defined dependence appeared to be increasing over time. Although these data suggest hardening may be occurring in treatment seekers but perhaps not in the general population of smokers, this conclusion may be premature given the small number of data sets and indirect measures of quit success and dependence in the data sets. Future studies should include questions about quit attempts, ability to abstain, treatment use, and multi-item dependence measures. PMID:21411244

  1. Testing the hypothesis on cognitive evolution of modern humans' learning ability: current status of past-climatic approaches.

    NASA Astrophysics Data System (ADS)

    Yoneda, Minoru; Abe-Ouchi, Ayako; Kawahata, Hodaka; Yokoyama, Yusuke; Oguchi, Takashi

    2014-05-01

    The impact of climate change on human evolution is important and debating topic for many years. Since 2010, we have involved in a general joint project entitled "Replacement of Neanderthal by Modern Humans: Testing Evolutional Models of Learning", which based on a theoretical prediction that the cognitive ability related to individual and social learning divide fates of ancient humans in very unstable Late Pleistocene climate. This model predicts that the human populations which experienced a series of environmental changes would have higher rate of individual learners, while detailed reconstructions of global climate change have reported fluent and drastic change based on ice cores and stalagmites. However, we want to understand the difference between anatomically modern human which survived and the other archaic extinct humans including European Neanderthals and Asian Denisovans. For this purpose the global synchronized change is not useful for understanding but the regional difference in the amplitude and impact of climate change is the information required. Hence, we invited a geophysicist busing Global Circulation Model to reconstruct the climatic distribution and temporal change in a continental scale. At the same time, some geochemists and geographers construct a database of local climate changes recorded in different proxies. At last, archaeologists and anthropologists tried to interpret the emergence and disappearance of human species in Europe and Asia on the reconstructed past climate maps using some tools, such as Eco-cultural niche model. Our project will show the regional difference in climate change and related archaeological events and its impact on the evolution of learning ability of modern humans.

  2. Examining the "evolution of increased competitive ability" hypothesis in response to parasites and pathogens in the invasive paper wasp Polistes dominula

    NASA Astrophysics Data System (ADS)

    Manfredini, Fabio; Grozinger, Christina M.; Beani, Laura

    2013-03-01

    Successful invaders often become established in new ranges by outcompeting native species. The "evolution of increased competitive ability" hypothesis predicts that invasive species are subjected to less predation and parasitization than sympatric native species, and thus can allocate resources from defence and immunity to growth and fecundity, thereby achieving higher fitness. In this study, we examined whether American invasive Polistes dominula paper wasps have reduced immunocompetence. To explore this scenario, we tested their susceptibility towards parasites and pathogens at both the individual (immune defence) and colony levels, i.e. hygienic behaviour (removal of diseased individuals by nestmates). First, we examined the response to the specific coevolved parasite Xenos vesparum (lost after invasion) in terms of individual host susceptibility and hygienic behaviour. Second, we explored the response against general pathogens by quantifying the bacterial clearance in individual wasps after a challenge with Escherichia coli and hygienic behaviour after a challenge with the fungus Beauveria bassiana. Our results show that American invasive P. dominula have a higher response against X. vesparum at the colony level, but at the individual level their susceptibility is not significantly different from conspecifics of the native range. On the other hand, invasive P. dominula display lower response after a challenge with general pathogens at both the individual and colony levels. While supporting the hypothesis of a reduction of immunocompetence towards general pathogens in invasive species, these findings also suggest that the response against coevolved parasites might follow different evolutionary pathways which are not always easily predictable.

  3. Examining the "evolution of increased competitive ability" hypothesis in response to parasites and pathogens in the invasive paper wasp Polistes dominula.

    PubMed

    Manfredini, Fabio; Beani, Laura; Grozinger, Christina M

    2013-03-01

    Successful invaders often become established in new ranges by outcompeting native species. The "evolution of increased competitive ability" hypothesis predicts that invasive species are subjected to less predation and parasitization than sympatric native species, and thus can allocate resources from defence and immunity to growth and fecundity, thereby achieving higher fitness. In this study, we examined whether American invasive Polistes dominula paper wasps have reduced immunocompetence. To explore this scenario, we tested their susceptibility towards parasites and pathogens at both the individual (immune defence) and colony levels, i.e. hygienic behaviour (removal of diseased individuals by nestmates). First, we examined the response to the specific coevolved parasite Xenos vesparum (lost after invasion) in terms of individual host susceptibility and hygienic behaviour. Second, we explored the response against general pathogens by quantifying the bacterial clearance in individual wasps after a challenge with Escherichia coli and hygienic behaviour after a challenge with the fungus Beauveria bassiana. Our results show that American invasive P. dominula have a higher response against X. vesparum at the colony level, but at the individual level their susceptibility is not significantly different from conspecifics of the native range. On the other hand, invasive P. dominula display lower response after a challenge with general pathogens at both the individual and colony levels. While supporting the hypothesis of a reduction of immunocompetence towards general pathogens in invasive species, these findings also suggest that the response against coevolved parasites might follow different evolutionary pathways which are not always easily predictable. PMID:23354757

  4. Selection on herbivory resistance and growth rate in an invasive plant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasive species face different conditions in their new range, which may lead to evolutionary change. The evolution of increased competitive ability (EICA) hypothesis proposes that invasive species evolve decreased defense and increased growth rate and competitive ability following introduction. W...

  5. Affective Feedback from Computers and its Effect on Perceived Ability and Affect: A Test of the Computers as Social Actor Hypothesis

    ERIC Educational Resources Information Center

    Mishra, Punya

    2006-01-01

    We report an experimental study that examined two questions: (a) The effect of affective feedback from computers on participants' motivation and self-perception of ability; and (b) whether people respond similarly to computer feedback as they do to human feedback. This study, framed within the Computers As Social Actors (CASA) framework,…

  6. Donepezil Treatment Restores the Ability of Estradiol to Enhance Cognitive Performance in Aged Rats: Evidence for the Cholinergic Basis of the Critical Period Hypothesis

    PubMed Central

    Gibbs, R.B.; Mauk, R.; Nelson, D.; Johnson, D.A.

    2009-01-01

    Recent studies suggest that the ability of estradiol to enhance cognitive performance diminishes with age and/or time following loss of ovarian function. We hypothesize that this is due, in part, to a decrease in basal forebrain cholinergic function. This study tested whether donepezil, a cholinesterase inhibitor, could restore estradiol effects on cognitive performance in aged rats that had been ovariectomized as young adults. Rats were ovariectomized at 3 months of age, and then trained on a delayed matching to position (DMP) T-maze task, followed by a configural association (CA) operant condition task, beginning at 12–17 or 22–27 months of age. Three weeks prior to testing, rats started to receive either donepezil or vehicle. After one week, half of each group also began receiving estradiol. Acclimation and testing began seven days later and treatment continued throughout testing. Estradiol alone significantly enhanced DMP acquisition in middle-aged rats, but not in aged rats. Donepezil alone had no effect on DMP acquisition in either age group; however, donepezil treatment restored the ability of estradiol to enhance DMP acquisition in aged rats. This effect was due largely to a reduction in the predisposition to adopt a persistent turn strategy during acquisition. These same treatments did not affect acquisition of the CA task in middle-aged rats, but did have small but significant effects on response time in aged rats. The data are consistent with the idea that estrogen effects on cognitive performance are task specific, and that deficits in basal forebrain cholinergic function are responsible for the loss of estradiol effect on DMP acquisition in aged ovariectomized rats. In addition, the data suggest that enhancing cholinergic function pharmacologically can restore the ability of estradiol to enhance acquisition of the DMP task in very old rats following long periods of hormone deprivation. Whether donepezil has similar restorative effects on other

  7. Threshold Hypothesis: Fact or Artifact?

    ERIC Educational Resources Information Center

    Karwowski, Maciej; Gralewski, Jacek

    2013-01-01

    The threshold hypothesis (TH) assumes the existence of complex relations between creative abilities and intelligence: linear associations below 120 points of IQ and weaker or lack of associations above the threshold. However, diverse results have been obtained over the last six decades--some confirmed the hypothesis and some rejected it. In this…

  8. Current Status of the Molecular Clock Hypothesis

    ERIC Educational Resources Information Center

    Hermann, Gilbert

    2003-01-01

    Molecular genetics is a rapidly changing field with new developments almost from day to day. One interesting hypothesis that has come from everyone's ability to sequence proteins and/or genes is that of the molecular clock. This hypothesis postulates that homologous sequences of DNA and thus macro molecules evolve at a constant and invariable rate…

  9. Physiopathological Hypothesis of Cellulite

    PubMed Central

    de Godoy, José Maria Pereira; de Godoy, Maria de Fátima Guerreiro

    2009-01-01

    A series of questions are asked concerning this condition including as regards to its name, the consensus about the histopathological findings, physiological hypothesis and treatment of the disease. We established a hypothesis for cellulite and confirmed that the clinical response is compatible with this hypothesis. Hence this novel approach brings a modern physiological concept with physiopathologic basis and clinical proof of the hypothesis. We emphasize that the choice of patient, correct diagnosis of cellulite and the technique employed are fundamental to success. PMID:19756187

  10. Life Origination Hydrate Hypothesis (LOH-Hypothesis)

    PubMed Central

    Ostrovskii, Victor; Kadyshevich, Elena

    2012-01-01

    The paper develops the Life Origination Hydrate Hypothesis (LOH-hypothesis), according to which living-matter simplest elements (LMSEs, which are N-bases, riboses, nucleosides, nucleotides), DNA- and RNA-like molecules, amino-acids, and proto-cells repeatedly originated on the basis of thermodynamically controlled, natural, and inevitable processes governed by universal physical and chemical laws from CH4, niters, and phosphates under the Earth's surface or seabed within the crystal cavities of the honeycomb methane-hydrate structure at low temperatures; the chemical processes passed slowly through all successive chemical steps in the direction that is determined by a gradual decrease in the Gibbs free energy of reacting systems. The hypothesis formulation method is based on the thermodynamic directedness of natural movement and consists ofan attempt to mentally backtrack on the progression of nature and thus reveal principal milestones alongits route. The changes in Gibbs free energy are estimated for different steps of the living-matter origination process; special attention is paid to the processes of proto-cell formation. Just the occurrence of the gas-hydrate periodic honeycomb matrix filled with LMSEs almost completely in its final state accounts for size limitation in the DNA functional groups and the nonrandom location of N-bases in the DNA chains. The slowness of the low-temperature chemical transformations and their “thermodynamic front” guide the gross process of living matter origination and its successive steps. It is shown that the hypothesis is thermodynamically justified and testable and that many observed natural phenomena count in its favor. PMID:25382120

  11. No evolution of reduced resistance and compensation for psyllid herbivory by the invasive Genista monspessulana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The evolution of redirecting resources from plant defense to growth or reproduction may explain why some exotic species are successful invaders in new environments. For example, the evolution of increased competitive ability hypothesis (EICA) posits that escape from herbivores by invasive plants re...

  12. No evidence for increased performance of a specialist psyllid on invasive French broom

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Some invasive plants perform better in their area of introduction than in their native region. This may be a consequence of rapid evolutionary change due to different selection pressures encountered in introduced regions. The Evolution of Increased Competitive Ability hypothesis (EICA) suggests th...

  13. Hypothesis analysis methods, hypothesis analysis devices, and articles of manufacture

    DOEpatents

    Sanfilippo, Antonio P.; Cowell, Andrew J.; Gregory, Michelle L.; Baddeley, Robert L.; Paulson, Patrick R.; Tratz, Stephen C.; Hohimer, Ryan E.

    2012-03-20

    Hypothesis analysis methods, hypothesis analysis devices, and articles of manufacture are described according to some aspects. In one aspect, a hypothesis analysis method includes providing a hypothesis, providing an indicator which at least one of supports and refutes the hypothesis, using the indicator, associating evidence with the hypothesis, weighting the association of the evidence with the hypothesis, and using the weighting, providing information regarding the accuracy of the hypothesis.

  14. Pilot model hypothesis testing

    NASA Technical Reports Server (NTRS)

    Broussard, J. R.; Berry, P. W.

    1982-01-01

    The aircraft control time history predicted by the optimal control pilot model and actual pilot tracking data obtained from NASA Langley's differential maneuvering simulator (DMS) are analyzed. The analysis is performed using a hypothesis testing scheme modified to allow for changes in the true hypothesis. A finite number of pilot models, each with different hypothesized internal model representations of the aircraft dynamics, are constructed. The hypothesis testing scheme determines the relative probability that each pilot model best matches the DMS data. By observing the changes in probabilities, it is possible to determine when the pilot changes control strategy and which hypothesized pilot model best represent's the pilot's control behavior.

  15. A specific hygiene hypothesis.

    PubMed

    Shunsheng Han, Cliff

    2016-08-01

    Allergic diseases have reached epidemic proportions in Western populations in the last several decades. The hygiene hypothesis proposed more than twenty years ago has helped us to understand the epidemic and has been verified with numerous studies. However, translational measures deduced from these studies to prevent allergic diseases have not proven effective. Recent studies on immigrants' allergies and any potential association between oral infection and allergic diseases prompt me to propose a specific hygiene hypothesis to explain how oral hygiene practices might have contributed to the uprising of hay fever, the most common allergic disease. The historic oral hygiene level in US is closely associated with the emerging allergic epidemic. Future studies to test the hypothesis are needed and verification of the hypothesis can potentially yield highly effective measures to prevent allergic diseases. PMID:27372876

  16. The Keystone Pathogen Hypothesis

    PubMed Central

    Hajishengallis, George; Darveau, Richard P.; Curtis, Michael A.

    2012-01-01

    Recent studies have highlighted the importance of the human microbiome in host health and disease. However, for the most part the mechanisms by which the microbiome mediates disease, or protection from it, remain poorly understood. The “keystone pathogen” hypothesis holds that certain low-abundance microbial pathogens can orchestrate inflammatory disease by remodelling a normally benign microbiota into a dysbiotic one. In this Opinion, we critically assess the available literature in support of this hypothesis, which may provide a novel conceptual basis for the development of targeted diagnostic and treatment modalities for complex dysbiotic diseases. PMID:22941505

  17. Testing the Pseudocrater Hypothesis

    NASA Astrophysics Data System (ADS)

    Payne, M. C.; Farmer, J. D.

    2003-07-01

    A field of coniform features observed in Olympia Planitia was hypothesized to be a pseudocrater field. We used a number of methods to test our hypothesis, as volcano-ice features located at the margin of a polar cap have significance for astrobiology.

  18. The Qualitative Similarity Hypothesis

    ERIC Educational Resources Information Center

    Paul, Peter V.; Lee, Chongmin

    2010-01-01

    Evidence is presented for the qualitative similarity hypothesis (QSH) with respect to children and adolescents who are d/Deaf or hard of hearing. The primary focus is on the development of English language and literacy skills, and some information is provided on the acquisition of English as a second language. The QSH is briefly discussed within…

  19. Two Applets for Teaching Hypothesis Testing

    ERIC Educational Resources Information Center

    Schneiter, Kady

    2008-01-01

    Interactive applets have the ability to enhance statistics teaching by providing multiple representations of new concepts and by facilitating experimentation. I introduce two applets that have been developed as aids in illustrating ideas relevant to hypothesis testing and describe how I have used these in my classes. (Contains 4 figures.)

  20. Levy-Reid hypothesis.

    PubMed

    Duckett, S; Gibson, W; Salama, M

    1993-07-01

    The inconsistencies in the research findings looking to test for the Levy-Reid hypothesis on the relationship between hand posture and laterality have been accounted for in various ways. Some authors (Cohen, 1991; Weber and Bradshaw, 1981) have suggested that existing methodologies for experimentally establishing laterality of language functioning are unreliable. To overcome this constraint, we have taken Halsey, Blauenstein, Wilson, and Wills' (1980) suggestion of using cerebrovascular accident (CVA) patients in which laterality of expressive speech has been established incontrovertibly. We examined 74 CVA subjects assessing hand posture, handedness, and side of stroke. Our findings lend support for Levy-Reid, nevertheless further examination of the hypothesis using a cross-cultural sample underscores the impact education and culture have on hand posture. PMID:8353727

  1. The interactive brain hypothesis

    PubMed Central

    Di Paolo, Ezequiel; De Jaegher, Hanne

    2012-01-01

    Enactive approaches foreground the role of interpersonal interaction in explanations of social understanding. This motivates, in combination with a recent interest in neuroscientific studies involving actual interactions, the question of how interactive processes relate to neural mechanisms involved in social understanding. We introduce the Interactive Brain Hypothesis (IBH) in order to help map the spectrum of possible relations between social interaction and neural processes. The hypothesis states that interactive experience and skills play enabling roles in both the development and current function of social brain mechanisms, even in cases where social understanding happens in the absence of immediate interaction. We examine the plausibility of this hypothesis against developmental and neurobiological evidence and contrast it with the widespread assumption that mindreading is crucial to all social cognition. We describe the elements of social interaction that bear most directly on this hypothesis and discuss the empirical possibilities open to social neuroscience. We propose that the link between coordination dynamics and social understanding can be best grasped by studying transitions between states of coordination. These transitions form part of the self-organization of interaction processes that characterize the dynamics of social engagement. The patterns and synergies of this self-organization help explain how individuals understand each other. Various possibilities for role-taking emerge during interaction, determining a spectrum of participation. This view contrasts sharply with the observational stance that has guided research in social neuroscience until recently. We also introduce the concept of readiness to interact to describe the practices and dispositions that are summoned in situations of social significance (even if not interactive). This latter idea links interactive factors to more classical observational scenarios. PMID:22701412

  2. Mesoamerican cosmovision: an hypothesis.

    NASA Astrophysics Data System (ADS)

    Franch, J. A.

    In the present conference the author explains a new hypothesis to interpret the cosmogonic vision of the people and the cultures from the Mesoamerican area during the precolumbian period. The hypothesis at issue consists in irregular octahedrical form, or as two pyramids jointed by the base in such a manner that the celestial pyramid has thirteen heavens in the form of platforms in such a way that the zenith is the seventh platform; on the contrary, the infraworld pyramid has nine platforms. The sequence of the heavens comes to an end in the number 13 heaven, or the West side of the world, that is to say the Omeyocan or the Tamoanchan, whereas the ninth infraworld is the Apochcalocan. This is the point of the intercommunication between the celestial world and the infraworld, the place of Death and Birth. In order to develop that hypothesis the author has a great number of ethnographic testimonies taken from Totonacs, Tzotziles, Mayas and, along with this, from Southamerican areas, as it is the case of the Kogi, of Colombia. The author has also considered the evidence that proceeds from the ancient codices as well as numerous samples of sculptures and reliefs, especially from the Aztec culture.

  3. Physiologic time: A hypothesis

    NASA Astrophysics Data System (ADS)

    West, Damien; West, Bruce J.

    2013-06-01

    The scaling of respiratory metabolism with body size in animals is considered by many to be a fundamental law of nature. One apparent consequence of this law is the scaling of physiologic time with body size, implying that physiologic time is separate and distinct from clock time. Physiologic time is manifest in allometry relations for lifespans, cardiac cycles, blood volume circulation, respiratory cycle, along with a number of other physiologic phenomena. Herein we present a theory of physiologic time that explains the allometry relation between time and total body mass averages as entailed by the hypothesis that the fluctuations in the total body mass are described by a scaling probability density.

  4. The qualitative similarity hypothesis.

    PubMed

    Paul, Peter V; Lee, Chongmin

    2010-01-01

    Evidence is presented for the qualitative similarity hypothesis (QSH) with respect to children and adolescents who are d/Deaf or hard of hearing. The primary focus is on the development of English language and literacy skills, and some information is provided on the acquisition of English as a second language. The QSH is briefly discussed within the purview of two groups of cognitive models: those that emphasize the cognitive development of individuals and those that pertain to disciplinary or knowledge structures. It is argued that the QSH has scientific merit with implications for classroom instruction. Future research should examine the validity of the QSH in other disciplines such as mathematics and science and should include perspectives from social as well as cognitive models. PMID:20415280

  5. Musical ability.

    PubMed

    Sloboda, J

    1993-01-01

    Musical ability is the ability to 'make sense' of music, and develops in most people over the first decade of life through normal enculturation. Whether this ability is developed to a high level usually depends on the decision to start learning a musical instrument, which forces high levels of focused cognitive engagement (practice) with musical materials. Performance ability has both technical and expressive aspects. These aspects are not always developed equally well. Factors contributing to the development of a well-balanced musical performer include (a) lengthy periods of engagement with music through practice and exploration, (b) high levels of material and emotional support from parents and other adults, (c) relationships with early teachers characterized by warmth and mutual liking, and (d) early experiences with music that promote, rather than inhibit, intense sensuous/affective experiences. It is argued that much formal education inhibits the development of musical ability through over-emphasis on assessment, creating performance anxiety, coupled with class and sex stereotyping of approved musical activities. Early free exploration of a medium is a necessity for the development of high levels of musicality. PMID:8168360

  6. The Importance of Teaching Power in Statistical Hypothesis Testing

    ERIC Educational Resources Information Center

    Olinsky, Alan; Schumacher, Phyllis; Quinn, John

    2012-01-01

    In this paper, we discuss the importance of teaching power considerations in statistical hypothesis testing. Statistical power analysis determines the ability of a study to detect a meaningful effect size, where the effect size is the difference between the hypothesized value of the population parameter under the null hypothesis and the true value…

  7. Teaching Hypothesis Testing by Debunking a Demonstration of Telepathy.

    ERIC Educational Resources Information Center

    Bates, John A.

    1991-01-01

    Discusses a lesson designed to demonstrate hypothesis testing to introductory college psychology students. Explains that a psychology instructor demonstrated apparent psychic abilities to students. Reports that students attempted to explain the instructor's demonstrations through hypothesis testing and revision. Provides instructions on performing…

  8. The pyrophilic primate hypothesis.

    PubMed

    Parker, Christopher H; Keefe, Earl R; Herzog, Nicole M; O'connell, James F; Hawkes, Kristen

    2016-01-01

    Members of genus Homo are the only animals known to create and control fire. The adaptive significance of this unique behavior is broadly recognized, but the steps by which our ancestors evolved pyrotechnic abilities remain unknown. Many hypotheses attempting to answer this question attribute hominin fire to serendipitous, even accidental, discovery. Using recent paleoenvironmental reconstructions, we present an alternative scenario in which, 2 to 3 million years ago in tropical Africa, human fire dependence was the result of adapting to progressively fire-prone environments. The extreme and rapid fluctuations between closed canopy forests, woodland, and grasslands that occurred in tropical Africa during that time, in conjunction with reductions in atmospheric carbon dioxide levels, changed the fire regime of the region, increasing the occurrence of natural fires. We use models from optimal foraging theory to hypothesize benefits that this fire-altered landscape provided to ancestral hominins and link these benefits to steps that transformed our ancestors into a genus of active pyrophiles whose dependence on fire for survival contributed to its rapid expansion out of Africa. PMID:27061034

  9. Is the Aluminum Hypothesis Dead?

    PubMed Central

    2014-01-01

    The Aluminum Hypothesis, the idea that aluminum exposure is involved in the etiology of Alzheimer disease, dates back to a 1965 demonstration that aluminum causes neurofibrillary tangles in the brains of rabbits. Initially the focus of intensive research, the Aluminum Hypothesis has gradually been abandoned by most researchers. Yet, despite this current indifference, the Aluminum Hypothesis continues to attract the attention of a small group of scientists and aluminum continues to be viewed with concern by some of the public. This review article discusses reasons that mainstream science has largely abandoned the Aluminum Hypothesis and explores a possible reason for some in the general public continuing to view aluminum with mistrust. PMID:24806729

  10. Human abilities.

    PubMed

    Sternberg, R J; Kaufman, J C

    1998-01-01

    This chapter reviews recent literature, primarily from the 1990s, on human abilities. The review opens with a consideration of the question of what intelligence is, and then considers some of the major definitions of intelligence, as well as implicit theories of intelligence around the world. Next, the chapter considers cognitive approaches to intelligence, and then biological approaches. It proceeds to psychometric or traditional approaches to intelligence, and then to broad, recent approaches. The different approaches raise somewhat different questions, and hence produce somewhat different answers. They have in common, however, the attempt to understand what kinds of mechanisms lead some people to adapt to, select, and shape environments in ways that match particularly well the demands of those environments. PMID:9496630

  11. On the Weyl curvature hypothesis

    NASA Astrophysics Data System (ADS)

    Stoica, Ovidiu Cristinel

    2013-11-01

    The Weyl curvature hypothesis of Penrose attempts to explain the high homogeneity and isotropy, and the very low entropy of the early universe, by conjecturing the vanishing of the Weyl tensor at the Big-Bang singularity.

  12. Evaluating the Stage Learning Hypothesis.

    ERIC Educational Resources Information Center

    Thomas, Hoben

    1980-01-01

    A procedure for evaluating the Genevan stage learning hypothesis is illustrated by analyzing Inhelder, Sinclair, and Bovet's guided learning experiments (in "Learning and the Development of Cognition." Cambridge: Harvard University Press, 1974). (Author/MP)

  13. Argument as Hypothesis-Testing.

    ERIC Educational Resources Information Center

    Zarefsky, David

    The argumentative perspective enables rhetoric to function in a manner analagous to science or analytic philosophy, yielding reliable knowledge about nonempirical topics, which other methods cannot address. In short, argumentation is the equivalent of hypothesis-testing. Forensics should offer laboratory experience in developing this perspective…

  14. On the Weyl curvature hypothesis

    SciTech Connect

    Stoica, Ovidiu Cristinel

    2013-11-15

    The Weyl curvature hypothesis of Penrose attempts to explain the high homogeneity and isotropy, and the very low entropy of the early universe, by conjecturing the vanishing of the Weyl tensor at the Big-Bang singularity. In previous papers it has been proposed an equivalent form of Einstein’s equation, which extends it and remains valid at an important class of singularities (including in particular the Schwarzschild, FLRW, and isotropic singularities). Here it is shown that if the Big-Bang singularity is from this class, it also satisfies the Weyl curvature hypothesis. As an application, we study a very general example of cosmological models, which generalizes the FLRW model by dropping the isotropy and homogeneity constraints. This model also generalizes isotropic singularities, and a class of singularities occurring in Bianchi cosmologies. We show that the Big-Bang singularity of this model is of the type under consideration, and satisfies therefore the Weyl curvature hypothesis. -- Highlights: •The singularities we introduce are described by finite geometric/physical objects. •Our singularities have smooth Riemann and Weyl curvatures. •We show they satisfy Penrose’s Weyl curvature hypothesis (Weyl=0 at singularities). •Examples: FLRW, isotropic singularities, an extension of Schwarzschild’s metric. •Example: a large class of singularities which may be anisotropic and inhomogeneous.

  15. THE BARKER HYPOTHESIS: IMPLICATIONS FOR FUTURE DIRECTIONS IN TOXICOLOGY RESEARCH

    EPA Science Inventory

    This review covers the past year’s papers germane to the Barker hypothesis. While much of the literature has centered on maternal and developmental nutrition, new findings have emerged on the ability of toxic exposures during development to impact fetal/developmental programming....

  16. [HYPOTHESIS OF FORMATION DURING THE EVOLUTION OF MECHANISM OF SENESCENCE].

    PubMed

    Makrushin, A V

    2015-01-01

    A hypothesis is in the evolution origin of the mechanism of senescence--is consequence of growth of individual integrity and thus loss ability to asexual reproduction. Evolutionary precursor of senescence mechanism was probably morphogenetic adaptation of potentially immortal precambrian Metazoa with which they adapted to the changing environment. PMID:26390606

  17. A Test of the Empathy-Effective Communication Hypothesis.

    ERIC Educational Resources Information Center

    Hogan, Robert; Henley, Nancy

    Psychologists and linguists often suggest that empathy or role-taking ability is important in the communication process because it enables a speaker to consider in advance the informational demands of his audience. Despite the vintage of the empathy-effective communication hypothesis, it has never been directly tested. In this study, empathy was…

  18. Numerical ability predicts mortgage default.

    PubMed

    Gerardi, Kristopher; Goette, Lorenz; Meier, Stephan

    2013-07-01

    Unprecedented levels of US subprime mortgage defaults precipitated a severe global financial crisis in late 2008, plunging much of the industrialized world into a deep recession. However, the fundamental reasons for why US mortgages defaulted at such spectacular rates remain largely unknown. This paper presents empirical evidence showing that the ability to perform basic mathematical calculations is negatively associated with the propensity to default on one's mortgage. We measure several aspects of financial literacy and cognitive ability in a survey of subprime mortgage borrowers who took out loans in 2006 and 2007, and match them to objective, detailed administrative data on mortgage characteristics and payment histories. The relationship between numerical ability and mortgage default is robust to controlling for a broad set of sociodemographic variables, and is not driven by other aspects of cognitive ability. We find no support for the hypothesis that numerical ability impacts mortgage outcomes through the choice of the mortgage contract. Rather, our results suggest that individuals with limited numerical ability default on their mortgage due to behavior unrelated to the initial choice of their mortgage. PMID:23798401

  19. Numerical ability predicts mortgage default

    PubMed Central

    Gerardi, Kristopher; Goette, Lorenz; Meier, Stephan

    2013-01-01

    Unprecedented levels of US subprime mortgage defaults precipitated a severe global financial crisis in late 2008, plunging much of the industrialized world into a deep recession. However, the fundamental reasons for why US mortgages defaulted at such spectacular rates remain largely unknown. This paper presents empirical evidence showing that the ability to perform basic mathematical calculations is negatively associated with the propensity to default on one’s mortgage. We measure several aspects of financial literacy and cognitive ability in a survey of subprime mortgage borrowers who took out loans in 2006 and 2007, and match them to objective, detailed administrative data on mortgage characteristics and payment histories. The relationship between numerical ability and mortgage default is robust to controlling for a broad set of sociodemographic variables, and is not driven by other aspects of cognitive ability. We find no support for the hypothesis that numerical ability impacts mortgage outcomes through the choice of the mortgage contract. Rather, our results suggest that individuals with limited numerical ability default on their mortgage due to behavior unrelated to the initial choice of their mortgage. PMID:23798401

  20. Changes in defense of an alien plant Ambrosia artemisiifolia before and after the invasion of a native specialist enemy Ophraella communa.

    PubMed

    Fukano, Yuya; Yahara, Tetsukazu

    2012-01-01

    The evolution of increased competitive ability hypothesis (EICA) predicts that when alien plants are free from their natural enemies they evolve lower allocation to defense in order to achieve a higher growth rate. If this hypothesis is true, the converse implication would be that the defense against herbivory could be restored if a natural enemy also becomes present in the introduced range. We tested this scenario in the case of Ambrosia artemisiifolia (common ragweed) - a species that invaded Japan from North America. We collected seeds from five North American populations, three populations in enemy free areas of Japan and four populations in Japan where the specialist herbivore Ophraella communa naturalized recently. Using plants grown in a common garden in Japan, we compared performance of O. communa with a bioassay experiment. Consistent with the EICA hypothesis, invasive Japanese populations of A. artemisiifolia exhibited a weakened defense against the specialist herbivores and higher growth rate than native populations. Conversely, in locations where the herbivore O. communa appeared during the past decade, populations of A. artemisiifolia exhibited stronger defensive capabilities. These results strengthen the case for EICA and suggest that defense levels of alien populations can be recuperated rapidly after the native specialist becomes present in the introduced range. Our study implies that the plant defense is evolutionary labile depending on plant-herbivore interactions. PMID:23145089

  1. Changes in Defense of an Alien Plant Ambrosia artemisiifolia before and after the Invasion of a Native Specialist Enemy Ophraella communa

    PubMed Central

    Fukano, Yuya; Yahara, Tetsukazu

    2012-01-01

    The evolution of increased competitive ability hypothesis (EICA) predicts that when alien plants are free from their natural enemies they evolve lower allocation to defense in order to achieve a higher growth rate. If this hypothesis is true, the converse implication would be that the defense against herbivory could be restored if a natural enemy also becomes present in the introduced range. We tested this scenario in the case of Ambrosia artemisiifolia (common ragweed) – a species that invaded Japan from North America. We collected seeds from five North American populations, three populations in enemy free areas of Japan and four populations in Japan where the specialist herbivore Ophraella communa naturalized recently. Using plants grown in a common garden in Japan, we compared performance of O. communa with a bioassay experiment. Consistent with the EICA hypothesis, invasive Japanese populations of A. artemisiifolia exhibited a weakened defense against the specialist herbivores and higher growth rate than native populations. Conversely, in locations where the herbivore O. communa appeared during the past decade, populations of A. artemisiifolia exhibited stronger defensive capabilities. These results strengthen the case for EICA and suggest that defense levels of alien populations can be recuperated rapidly after the native specialist becomes present in the introduced range. Our study implies that the plant defense is evolutionary labile depending on plant-herbivore interactions. PMID:23145089

  2. The "Eye Avoidance" Hypothesis of Autism Face Processing.

    PubMed

    Tanaka, James W; Sung, Andrew

    2016-05-01

    Although a growing body of research indicates that children with autism spectrum disorder (ASD) exhibit selective deficits in their ability to recognize facial identities and expressions, the source of their face impairment is, as yet, undetermined. In this paper, we consider three possible accounts of the autism face deficit: (1) the holistic hypothesis, (2) the local perceptual bias hypothesis and (3) the eye avoidance hypothesis. A review of the literature indicates that contrary to the holistic hypothesis, there is little evidence to suggest that individuals with autism do perceive faces holistically. The local perceptual bias account also fails to explain the selective advantage that ASD individuals demonstrate for objects and their selective disadvantage for faces. The eye avoidance hypothesis provides a plausible explanation of face recognition deficits where individuals with ASD avoid the eye region because it is perceived as socially threatening. Direct eye contact elicits a increased physiological response as indicated by heightened skin conductance and amygdala activity. For individuals with autism, avoiding the eyes is an adaptive strategy, however, this approach interferes with the ability to process facial cues of identity, expressions and intentions, exacerbating the social challenges for persons with ASD. PMID:24150885

  3. In search of the hypothesis.

    PubMed Central

    Kaufman, J S; Cooper, R S

    1995-01-01

    Epidemiologic studies of racial differences sorely lack sound and explicit hypotheses. Race is a social convention, not a biological concept. Its careless use in epidemiology demonstrates a failure to generate appropriate hypotheses to study its role in health. Studies of hypertension in blacks illustrate the point. Two underlying pitfalls plague hypothesis generation: directionality involving the null and alternative hypotheses and circularity, where efforts to understand social factors have the effect of emphasizing racial differences. The proper prescription is to identify explicitly the hypotheses of interest, including their origins and implication. Images p662-a p665-a PMID:8570813

  4. Beyond the Black Queen Hypothesis.

    PubMed

    Mas, Alix; Jamshidi, Shahrad; Lagadeuc, Yvan; Eveillard, Damien; Vandenkoornhuyse, Philippe

    2016-09-01

    The Black Queen Hypothesis, recently proposed to explain an evolution of dependency based on gene loss, is gaining ground. This paper focuses on how the evolution of dependency transforms interactions and the community. Using agent-based modeling we suggest that species specializing in the consumption of a common good escape competition and therefore favor coexistence. This evolutionary trajectory could open the way for novel long-lasting interactions and a need to revisit the classically accepted assembly rules. Such evolutionary events also reshape the structure and dynamics of communities, depending on the spatial heterogeneity of the common good production. Let Black be the new black! PMID:26953598

  5. A Molecular–Structure Hypothesis

    PubMed Central

    Boeyens, Jan C. A.

    2010-01-01

    The self-similar symmetry that occurs between atomic nuclei, biological growth structures, the solar system, globular clusters and spiral galaxies suggests that a similar pattern should characterize atomic and molecular structures. This possibility is explored in terms of the current molecular structure-hypothesis and its extension into four-dimensional space-time. It is concluded that a quantum molecule only has structure in four dimensions and that classical (Newtonian) structure, which occurs in three dimensions, cannot be simulated by quantum-chemical computation. PMID:21151437

  6. Hypothesis tests for hydrologic alteration

    NASA Astrophysics Data System (ADS)

    Kroll, Charles N.; Croteau, Kelly E.; Vogel, Richard M.

    2015-11-01

    Hydrologic systems can be altered by anthropogenic and climatic influences. While there are a number of statistical frameworks for describing and evaluating the extent of hydrologic alteration, here we present a new framework for assessing whether statistically significant hydrologic alteration has occurred, or whether the shift in the hydrologic regime is consistent with the natural variability of the system. Four hypothesis tests based on shifts of flow duration curves (FDCs) are developed and tested using three different experimental designs based on different strategies for resampling of annual FDCs. The four hypothesis tests examined are the Kolmogorov-Smirnov (KS), Kuiper (K), confidence interval (CI), and ecosurplus and ecodeficit (Eco). Here 117 streamflow sites that have potentially undergone hydrologic alteration due to reservoir construction are examined. 20 years of pre-reservoir record is used to develop the critical value of the test statistic for type I errors of 5% and 10%, while 10 years of post-alteration record is used to examine the power of each test. The best experimental design, based on calculating the mean annual FDC from an exhaustive jackknife resampling regime, provided a larger number of unique values of each test statistic and properly reproduced type I errors. Of the four tests, the CI test consistently had the highest power, while the K test had the second highest power; KS and Eco always had the lowest power. The power of the CI test appeared related to the storage ratio of the reservoir, a rough measure of the hydrologic alteration of the system.

  7. The selection-arena hypothesis.

    PubMed

    Stearns, S C

    1987-01-01

    The selection arena hypothesis offers one answer to a puzzling question. Why do some organisms produce many more fertilized zygotes than are actually reared to hatching, birth, or release-then neglect, discard, resorb, or eat some of them, or allow them to eat each other? It makes four assumptions: (1) zygotes are cheap; (2) after conception the investment of parental time, energy, or risk into offspring continues; (3) offspring vary in fitness; (4) variation in offspring fitness can be identified by the mother at an early stage of the life cycle. If these assumptions hold, then one general prediction follows: the parent should overproduce zygotes, identify those with lower expected fitness, then either kill and reabsorb them, let them be eaten by sibs, or simply stop feeding them in order to invest in more promising offspring. The explanation appears to apply to a wide range of phenomena whose common cause had not previously been appreciated. These include: (1) polyovulation in some bats, tenrecs, the plains viscacha, and the pronghorn antelope; (2) cases of recurrent, consecutive, spontaneous abortions in humans; (3) some cases of surplus flower production and fruit abortion; (4) sex-ratio adjustment in red deer, mice, and coypus; (5) some types of cannibalism, including possible cases in mice, sharks, and wasps. Some cases that might be explained by the selection arena hypothesis are also plausibly explained by other causes, including bet-hedging reproductive investment in the face of unpredictable food supplies, and inter-specific or inter-familial aggression as an alternative to parent-offspring or sib-sib cannibalism. PMID:2961604

  8. Self-Efficacy, Reasoning Ability, and Achievement in College Biology

    ERIC Educational Resources Information Center

    Lawson, Anton E.; Banks, Debra L.; Logvin, Marshall

    2007-01-01

    This study compared the relationships of self-efficacy and reasoning ability to achievement in introductory college biology. Based on the hypothesis that developing formal and postformal reasoning ability is a primary factor influencing self-efficacy, a significant positive correlation was predicted between reasoning ability and degree of…

  9. Planning Ability across Ranges of Intellectual Ability: An Examination of the Luria-Das Information-Processing Model.

    ERIC Educational Resources Information Center

    McCallum, R. Steve; And Others

    1988-01-01

    Based on Luria-Das information processing theory, hypothesized that 26 educable mentally retarded children would score significantly less well on relatively pure measures of planning ability than would 13 younger average ability students after students were matched on cognitive processing ability. Hypothesis was not supported by study. (Author/NB)

  10. Conceptual Systems Model as a Tool for Hypothesis Generation and Testing in Ecotoxicological Research

    EPA Science Inventory

    Microarray, proteomic, and metabonomic technologies are becoming increasingly accessible as tools for ecotoxicology research. Effective use of these technologies will depend, at least in part, on the ability to apply these techniques within a paradigm of hypothesis driven researc...

  11. No evidence for increased performance of a specialist psyllid on invasive French broom

    NASA Astrophysics Data System (ADS)

    Herrera, Angelica M.; Carruthers, Raymond I.; Mills, Nicholas J.

    2011-03-01

    Some invasive plants perform better in their area of introduction than in their native region. This may be a consequence of rapid evolutionary change due to different selection pressures encountered in introduced regions. The Evolution of Increased Competitive Ability hypothesis (EICA) suggests that release from natural enemies results in selection of more vigorous plant genotypes as a result of plants allocating resources away from costly herbivore-resistance traits and toward increased growth. We tested the prediction that introduced plant genotypes of Genista monspessulana (Fabaceae) are less resistant to herbivory by a specialist psyllid, Arytinnis hakani (Hemiptera: Psyllidae) by measuring and comparing A. hakani performance on plants from native (southern France) and introduced (California, U.S.) populations. A. hakani performed equally well on plants from the native and introduced regions; there were no significant differences in psyllid egg and nymphal development, nymphal survival rates, female longevity or fecundity between the test plants. Egg survival rates were significantly higher on native populations, but the difference was minimal. These results provide preliminary evidence that native and introduced G. monspessulana populations are equally resistant to A. hakani and do not support the EICA hypothesis prediction of reduced investment in defense in introduced plant populations. Possible explanations for the lack of effects found in this study include the type of parameters measured and the feeding ecology of the herbivore used to test EICA, and finally, that evolutionary changes in plant defense in introduced G. monspessulana populations may not have occurred.

  12. The Over-Pruning Hypothesis of Autism

    ERIC Educational Resources Information Center

    Thomas, Michael S. C.; Davis, Rachael; Karmiloff-Smith, Annette; Knowland, Victoria C. P.; Charman, Tony

    2016-01-01

    This article outlines the "over-pruning hypothesis" of autism. The hypothesis originates in a neurocomputational model of the regressive sub-type (Thomas, Knowland & Karmiloff-Smith, 2011a, 2011b). Here we develop a more general version of the over-pruning hypothesis to address heterogeneity in the timing of manifestation of ASD,…

  13. Hypothesis: neoplasms in myotonic dystrophy

    PubMed Central

    Hilbert, James E.; Martens, William; Thornton, Charles A.; Moxley, Richard T.; Greene, Mark H.

    2011-01-01

    Tumorigenesis is a multi-step process due to an accumulation of genetic mutations in multiple genes in diverse pathways which ultimately lead to loss of control over cell growth. It is well known that inheritance of rare germline mutations in genes involved in tumorigenesis pathways confer high lifetime risk of neoplasia in affected individuals. Furthermore, a substantial number of multiple malformation syndromes include cancer susceptibility in their phenotype. Studies of the mechanisms underlying these inherited syndromes have added to the understanding of both normal development and the pathophysiology of carcinogenesis. Myotonic dystrophy (DM) represents a group of autosomal dominant, multisystemic diseases that share the clinical features of myotonia, muscle weakness, and early-onset cataracts. Myotonic dystrophy type 1 (DM1) and myotonic dystrophy type 2 (DM2) result from unstable nucleotide repeat expansions in their respective genes. There have been multiple reports of tumors in individuals with DM, most commonly benign calcifying cutaneous tumors known as pilomatricomas. We provide a summary of the tumors reported in DM and a hypothesis for a possible mechanism of tumorigenesis. We hope to stimulate further study into the potential role of DM genes in tumorigenesis, and help define DM pathogenesis, and facilitate developing novel treatment modalities. PMID:19642006

  14. Bayesian Hypothesis Testing for Planet Finding

    NASA Astrophysics Data System (ADS)

    Braems, I.; Kasdin, N. J.

    2003-12-01

    One of the most important performance metrics of any space planet finding system is integration time. The time needed to make a positive detection of an extrasolar planet determines the number of systems we can observe for the life of the mission and the stability requirements of the spacecraft and optical control systems. Most astronomical detection approaches rely on fairly simple signal-to-noise calculations and a threshold determined by the ability of the human eye to extract the planet image from the background (usually a signal-to-noise ratio of five). In this paper we present an alternative approach to detection using Bayesian hypothesis testing. This optimal approach provides a quantitative measure of the probability of detection under various conditions and integration times (such as known or unknown background levels) and under different prior assumptions. We also show how the technique allows for a much higher probability of detection for shorter integration times than the previous photometric approaches. We gratefully acknowledge the support of the Jet Propulsion Laboratory of the National Aeronautics and Space Administration for this work and Institut National de Recherche en Informatique et Automatique (INRIA) for its support of Ms. Braems.

  15. AgrAbility Project

    MedlinePlus

    About Us Search Search for: AgrAbility Assisting farmers and ranchers with disabilities. Menu Skip to content Home About AgrAbility Newsletters (old) AT Resources AT Database Staff Development Archive Contact Us We ...

  16. Competence and ability.

    PubMed

    Vogelstein, Eric

    2014-06-01

    It is nearly universally thought that the kind of decision-making competence that gives one a strong prima facie right to make one's own medical decisions essentially involves having an ability (or abilities) of some sort, or having a certain level or degree of ability (or abilities). When put under philosophical scrutiny, however, this kind of theory does not hold up. I will argue that being competent does not essentially involve abilities, and I will propose and defend a theory of decision-making competence according to which one is competent only if one possesses a certain kind of rationality in making treatment decisions. PMID:22845798

  17. The Interaction Hypothesis: A Literature Review

    ERIC Educational Resources Information Center

    Tran, Thu Hoang

    2009-01-01

    This paper will examine the interaction hypothesis (IH) in second language acquisition (SLA). To begin with a short discussion of the confusing terms in SLA such as theory, model, hypothesis, and construct will be done so as to help readers easily understand theories in the field of SLA and related concepts. Next, what the IH is, and who proposed…

  18. The Interaction Hypothesis: A Critical Evaluation.

    ERIC Educational Resources Information Center

    Ellis, Rod

    The oral interaction hypothesis, proposed by Long and investigated by Pica, in second language (L2) acquisition is critiqued. The interaction hypothesis advances two major claims about the role of interaction in L2 acquisition: (1) comprehensible input is necessary for L2 acquisition; and (2) modifications to the interactional structure of…

  19. Ecosystem Succession and Nutrient Retention: A Hypothesis

    ERIC Educational Resources Information Center

    Vitousek, Peter M.; Reiners, William A.

    1975-01-01

    A hypothesis is presented for the regulation of elemental losses from terrestrial ecosystems. Losses of elements are controlled by the net increment of biomass growth and the elemental composition of this net increment. According to this hypothesis, loss rates are highest in early succession and in steady state ecosystems. (Author/EB)

  20. A Model of the Relative Income Hypothesis

    ERIC Educational Resources Information Center

    Sanders, Shane

    2010-01-01

    James Duesenberry's (1949) relative income hypothesis holds substantial empirical credibility, as well as a rich set of implications. Although present in the pages of leading economics journals, the hypothesis has become all but foreign to the blackboards of economics classrooms. To help reintegrate the concept into the undergraduate economics…

  1. Statistics and Hypothesis Testing in Biology.

    ERIC Educational Resources Information Center

    Maret, Timothy J.; Ziemba, Robert E.

    1997-01-01

    Suggests that early in their education students be taught to use basic statistical tests as rigorous methods of comparing experimental results with scientific hypotheses. Stresses that students learn how to use statistical tests in hypothesis-testing by applying them in actual hypothesis-testing situations. To illustrate, uses questions such as…

  2. A Test of the Urban Overload Hypothesis.

    ERIC Educational Resources Information Center

    McCauley, Clark R.

    This paper briefly discusses three studies aimed at exploring the overload hypothesis posited by Stanley Milgram. That hypothesis suggests that impoverished social interaction in the city is an adaptation to overload of interpersonal contacts. The three studies examine various aspects of the phenomenon using different methodologies. Comparing city…

  3. A Twin Study of the Etiology of High Reading Ability.

    ERIC Educational Resources Information Center

    Boada, Richard; Willcutt, Erik G.; Tunick, Rachel A.; Chhabildas, Nomita A.; Olson, Richard K.; DeFries, John C.; Pennington, Bruce F.

    2002-01-01

    Examines the etiology of high reading ability in twin pairs. Suggests that reading ability and its cognitive correlates are on a continuous distribution, with both extremes of the distribution being similarly heritable. Supports the hypothesis that the same cognitive processes that are associated with dyslexia are important for the development of…

  4. Spatial Abilities of Medical Graduates and Choice of Residency Programs

    ERIC Educational Resources Information Center

    Langlois, Jean; Wells, George A.; Lecourtois, Marc; Bergeron, Germain; Yetisir, Elizabeth; Martin, Marcel

    2015-01-01

    Spatial abilities have been related in previous studies to three-dimensional (3D) anatomy knowledge and the performance in technical skills. The objective of this study was to relate spatial abilities to residency programs with different levels of content of 3D anatomy knowledge and technical skills. The hypothesis was that the choice of residency…

  5. Spatial Ability in Relatives of Reading-Disabled Children.

    ERIC Educational Resources Information Center

    Decker, Sadie N.

    A Study was conducted to test the hypothesis proposed by J. S. Symmes and J. L. Rapoport that a sex-linked recessive gene might account for the good spatial ability found among dyslexic readers, the familial pattern of the disorder, and the frequently reported sex ratio of three affected males to one female. Spatial/reasoning ability scores were…

  6. The Effect of Fluid Ability, Visual Ability, and Visual Placement within the Screen on a Simple Concept Task.

    ERIC Educational Resources Information Center

    Hart, Russ A.

    This exploratory study was conducted to investigate the potential interaction between the media attribute, horizontal screen placement, and a learner's cognitive aptitudes, fluid ability, and visualization. The primary hypothesis tested was that low-ability learners who are without well-developed assembly and control operations should perform…

  7. Knowledge dimensions in hypothesis test problems

    NASA Astrophysics Data System (ADS)

    Krishnan, Saras; Idris, Noraini

    2012-05-01

    The reformation in statistics education over the past two decades has predominantly shifted the focus of statistical teaching and learning from procedural understanding to conceptual understanding. The emphasis of procedural understanding is on the formulas and calculation procedures. Meanwhile, conceptual understanding emphasizes students knowing why they are using a particular formula or executing a specific procedure. In addition, the Revised Bloom's Taxonomy offers a twodimensional framework to describe learning objectives comprising of the six revised cognition levels of original Bloom's taxonomy and four knowledge dimensions. Depending on the level of complexities, the four knowledge dimensions essentially distinguish basic understanding from the more connected understanding. This study identifiesthe factual, procedural and conceptual knowledgedimensions in hypothesis test problems. Hypothesis test being an important tool in making inferences about a population from sample informationis taught in many introductory statistics courses. However, researchers find that students in these courses still have difficulty in understanding the underlying concepts of hypothesis test. Past studies also show that even though students can perform the hypothesis testing procedure, they may not understand the rationale of executing these steps or know how to apply them in novel contexts. Besides knowing the procedural steps in conducting a hypothesis test, students must have fundamental statistical knowledge and deep understanding of the underlying inferential concepts such as sampling distribution and central limit theorem. By identifying the knowledge dimensions of hypothesis test problems in this study, suitable instructional and assessment strategies can be developed in future to enhance students' learning of hypothesis test as a valuable inferential tool.

  8. Hypothesis-free? No such thing

    SciTech Connect

    Wiley, H. S.

    2008-06-01

    Finding meaningful relationships in complex datasets requires starting with the appropriate data. A hypothesis usually takes the form of a mechanistic relationship between a specific cause and a consequent effect, and this will almost always depend on experimental context. There are some circumstances when data must be gathered in the absence of context or hypothesis to characterize a system, but it is unrealistic to expect such preliminary studies to lead to significant biological insights. For this, you need a hypothesis. Systems biology might be the future of biology, but we still need hypotheses to take us where we want to go.

  9. Scientific Ability and Creativity

    ERIC Educational Resources Information Center

    Heller, Kurt A.

    2007-01-01

    Following an introductory definition of "scientific ability and creativity", product-oriented, personality and social psychological approaches to studying scientific ability are examined with reference to competence and performance. Studies in the psychometric versus cognitive psychological paradigms are dealt with in more detail. These two…

  10. Putting Down the Discovery Learning Hypothesis

    ERIC Educational Resources Information Center

    Chambers, David W.

    1971-01-01

    The author analyzes some of the conceptual problems which have prevented a direct test of the discovery learning hypothesis, provides an operational definition of discovery learning, and proposes an improved experimental paradigm. Appended are 38 references. (AA)

  11. Killing Me Softly: The Fetal Origins Hypothesis.

    PubMed

    Almond, Douglas; Currie, Janet

    2011-01-01

    In the epidemiological literature, the fetal origins hypothesis associated with David J. Barker posits that chronic, degenerative conditions of adult health, including heart disease and type 2 diabetes, may be triggered by circumstance decades earlier, in utero nutrition in particular. Economists have expanded on this hypothesis, investigating a broader range of fetal shocks and circumstances and have found a wealth of later-life impacts on outcomes including test scores, educational attainment, and income, along with health. In the process, they have provided some of the most credible observational evidence in support of the hypothesis. The magnitude of the impacts is generally large. Thus, the fetal origins hypothesis has not only survived contact with economics, but has flourished. PMID:25152565

  12. The silica hypothesis for homeopathy: physical chemistry.

    PubMed

    Anick, David J; Ives, John A

    2007-07-01

    The 'silica hypothesis' is one of several frameworks that have been put forward to explain how homeopathic remedies, which often are diluted beyond the point where any of the original substance remains, might still be clinically effective. We describe here what the silica hypothesis says. From a physical chemistry viewpoint, we explore three challenges that the hypothesis would have to meet in order to explain homeopathy: thermodynamic stability of a large number of distinct structures, pattern initiation at low potencies, and pattern maintenance or gradual evolution at higher potencies. We juxtapose current knowledge about silicates with some of the conventional wisdom about homeopathic remedies, to see how well the latter might be a consequence of the former. We explore variants of the hypothesis including some speculations about mechanisms. We outline laboratory experiments that could help to decide it. PMID:17678816

  13. Killing Me Softly: The Fetal Origins Hypothesis*

    PubMed Central

    Almond, Douglas

    2013-01-01

    In the epidemiological literature, the fetal origins hypothesis associated with David J. Barker posits that chronic, degenerative conditions of adult health, including heart disease and type 2 diabetes, may be triggered by circumstance decades earlier, in utero nutrition in particular. Economists have expanded on this hypothesis, investigating a broader range of fetal shocks and circumstances and have found a wealth of later-life impacts on outcomes including test scores, educational attainment, and income, along with health. In the process, they have provided some of the most credible observational evidence in support of the hypothesis. The magnitude of the impacts is generally large. Thus, the fetal origins hypothesis has not only survived contact with economics, but has flourished. PMID:25152565

  14. A Theoretical Note on Sex Linkage and Race Differences in Spatial Visualization Ability

    ERIC Educational Resources Information Center

    Jensen, Arthur R.

    1975-01-01

    Evidence on the poorer spatial visualization ability in various Negro populations compared to the White populations and on the direction and magnitude of sex differences in spatial ability relative to other abilities suggests the genetic hypothesis that spatial ability is enhanced by a sex-linked recessive gene and that, since the 20-30 percent…

  15. Measuring creative imagery abilities

    PubMed Central

    Jankowska, Dorota M.; Karwowski, Maciej

    2015-01-01

    Over the decades, creativity and imagination research developed in parallel, but they surprisingly rarely intersected. This paper introduces a new theoretical model of creative visual imagination, which bridges creativity and imagination research, as well as presents a new psychometric instrument, called the Test of Creative Imagery Abilities (TCIA), developed to measure creative imagery abilities understood in accordance with this model. Creative imagination is understood as constituted by three interrelated components: vividness (the ability to create images characterized by a high level of complexity and detail), originality (the ability to produce unique imagery), and transformativeness (the ability to control imagery). TCIA enables valid and reliable measurement of these three groups of abilities, yielding the general score of imagery abilities and at the same time making profile analysis possible. We present the results of nine studies on a total sample of more than 1700 participants, showing the factor structure of TCIA using confirmatory factor analysis, as well as provide data confirming this instrument's validity and reliability. The availability of TCIA for interested researchers may result in new insights and possibilities of integrating the fields of creativity and imagination science. PMID:26539140

  16. Measuring creative imagery abilities.

    PubMed

    Jankowska, Dorota M; Karwowski, Maciej

    2015-01-01

    Over the decades, creativity and imagination research developed in parallel, but they surprisingly rarely intersected. This paper introduces a new theoretical model of creative visual imagination, which bridges creativity and imagination research, as well as presents a new psychometric instrument, called the Test of Creative Imagery Abilities (TCIA), developed to measure creative imagery abilities understood in accordance with this model. Creative imagination is understood as constituted by three interrelated components: vividness (the ability to create images characterized by a high level of complexity and detail), originality (the ability to produce unique imagery), and transformativeness (the ability to control imagery). TCIA enables valid and reliable measurement of these three groups of abilities, yielding the general score of imagery abilities and at the same time making profile analysis possible. We present the results of nine studies on a total sample of more than 1700 participants, showing the factor structure of TCIA using confirmatory factor analysis, as well as provide data confirming this instrument's validity and reliability. The availability of TCIA for interested researchers may result in new insights and possibilities of integrating the fields of creativity and imagination science. PMID:26539140

  17. AgrAbility Project

    MedlinePlus

    ... About AgrAbility State Projects Directory The Toolbox AT Database Resources Veterans & Beginning Farmers Communities of Interest News ... 800) 825-4264 Home About The Toolbox AT Database Resources Online Training Contact Us You are here: ...

  18. Darwinian evolution does not rule out the gaia hypothesis.

    PubMed

    Sugimoto, Takeshi

    2002-10-21

    This study explores so-called Darwinian Daisyworlds mathematically rigorously in detail. The original Daisyworld was introduced by Watson & Lovelock (1983) to demonstrate how two species of daisies regulate the global temperature of their planet through competition among these species against the rising solar luminosity, i.e. the Gaia hypothesis. Its variants are Darwinian Daisyworlds in which daisies can adapt themselves to the local temperature. Robertson & Robinson (1998) insist their Darwinian daisies lose the ability for temperature regulation on the basis of their spreadsheet simulations. Lenton & Lovelock (2000) point out that the constraints on adaptation recovers Darwinian daisies' ability of temperature regulation on the basis of their Euler-code simulations. The present study shows there exist the exact and closed-form solutions to these two Daisyworlds. The results contradict the former studies: Robertson and Robinson's daisies do regulate the global temperature even longer than non-adaptive daisies; Lenton and Lovelock's daisies are less adaptive than Robertson and Robinson's daisies because of the constraints on adaptation; the introduction of weak adaptability drives species into a dead end of evolution. Thus, the present results confirm that the Gaia hypothesis and Darwinian evolution can coexist. PMID:12384048

  19. Basic statistics for clinicians: 1. Hypothesis testing.

    PubMed Central

    Guyatt, G; Jaeschke, R; Heddle, N; Cook, D; Shannon, H; Walter, S

    1995-01-01

    In the first of a series of four articles the authors explain the statistical concepts of hypothesis testing and p values. In many clinical trials investigators test a null hypothesis that there is no difference between a new treatment and a placebo or between two treatments. The result of a single experiment will almost always show some difference between the experimental and the control groups. Is the difference due to chance, or is it large enough to reject the null hypothesis and conclude that there is a true difference in treatment effects? Statistical tests yield a p value: the probability that the experiment would show a difference as great or greater than that observed if the null hypothesis were true. By convention, p values of less than 0.05 are considered statistically significant, and investigators conclude that there is a real difference. However, the smaller the sample size, the greater the chance of erroneously concluding that the experimental treatment does not differ from the control--in statistical terms, the power of the test may be inadequate. Tests of several outcomes from one set of data may lead to an erroneous conclusion that an outcome is significant if the joint probability of the outcomes is not taken into account. Hypothesis testing has limitations, which will be discussed in the next article in the series. PMID:7804919

  20. Multiple hypothesis tracking for the cyber domain

    NASA Astrophysics Data System (ADS)

    Schwoegler, Stefan; Blackman, Sam; Holsopple, Jared; Hirsch, Michael J.

    2011-09-01

    This paper discusses how methods used for conventional multiple hypothesis tracking (MHT) can be extended to domain-agnostic tracking of entities from non-kinematic constraints such as those imposed by cyber attacks in a potentially dense false alarm background. MHT is widely recognized as the premier method to avoid corrupting tracks with spurious data in the kinematic domain but it has not been extensively applied to other problem domains. The traditional approach is to tightly couple track maintenance (prediction, gating, filtering, probabilistic pruning, and target confirmation) with hypothesis management (clustering, incompatibility maintenance, hypothesis formation, and Nassociation pruning). However, by separating the domain specific track maintenance portion from the domain agnostic hypothesis management piece, we can begin to apply the wealth of knowledge gained from ground and air tracking solutions to the cyber (and other) domains. These realizations led to the creation of Raytheon's Multiple Hypothesis Extensible Tracking Architecture (MHETA). In this paper, we showcase MHETA for the cyber domain, plugging in a well established method, CUBRC's INFormation Engine for Real-time Decision making, (INFERD), for the association portion of the MHT. The result is a CyberMHT. We demonstrate the power of MHETA-INFERD using simulated data. Using metrics from both the tracking and cyber domains, we show that while no tracker is perfect, by applying MHETA-INFERD, advanced nonkinematic tracks can be captured in an automated way, perform better than non-MHT approaches, and decrease analyst response time to cyber threats.

  1. The neural rejuvenation hypothesis of cocaine addiction.

    PubMed

    Dong, Yan; Nestler, Eric J

    2014-08-01

    A leading hypothesis guiding current molecular and cellular research into drug addiction conceptualizes key aspects of addiction as a form of memory in which common neuroplasticity mechanisms that mediate normal learning and memory processes are 'hijacked' by exposure to drugs of abuse to produce pathologic addiction-related memories. Such addiction-related memories are particularly robust and long-lasting and once formed are less amenable to updating. Here we propose a neural rejuvenation hypothesis of cocaine addiction. According to this hypothesis, repeated exposure to drugs of abuse induces some plasticity mechanisms normally associated with brain development within the reward circuitry that mediate the highly efficient and unusually stable memory abnormalities that characterize addiction. PMID:24958329

  2. The over-pruning hypothesis of autism.

    PubMed

    Thomas, Michael S C; Davis, Rachael; Karmiloff-Smith, Annette; Knowland, Victoria C P; Charman, Tony

    2016-03-01

    This article outlines the over-pruning hypothesis of autism. The hypothesis originates in a neurocomputational model of the regressive sub-type (Thomas, Knowland & Karmiloff-Smith, 2011a, 2011b). Here we develop a more general version of the over-pruning hypothesis to address heterogeneity in the timing of manifestation of ASD, including new computer simulations which reconcile the different observed developmental trajectories (early onset, late onset, regression) via a single underlying atypical mechanism; and which show how unaffected siblings of individuals with ASD may differ from controls either by inheriting a milder version of the pathological mechanism or by co-inheriting the risk factors without the pathological mechanism. The proposed atypical mechanism involves overly aggressive synaptic pruning in infancy and early childhood, an exaggeration of a normal phase of brain development. We show how the hypothesis generates novel predictions that differ from existing theories of ASD including that (1) the first few months of development in ASD will be indistinguishable from typical, and (2) the earliest atypicalities in ASD will be sensory and motor rather than social. Both predictions gain cautious support from emerging longitudinal studies of infants at-risk of ASD. We review evidence consistent with the over-pruning hypothesis, its relation to other current theories (including C. Frith's under-pruning proposal; C. Frith, 2003, 2004), as well as inconsistent data and current limitations. The hypothesis situates causal accounts of ASD within a framework of protective and risk factors (Newschaffer et al., 2012); clarifies different versions of the broader autism phenotype (i.e. the implication of observed similarities between individuals with autism and their family members); and integrates data from multiple disciplines, including behavioural studies, neuroscience studies, genetics, and intervention studies. PMID:25845529

  3. An excitatory synapse hypothesis of depression

    PubMed Central

    Thompson, Scott M.; Kallarackal, Angy J.; Kvarta, Mark D.; Van Dyke, Adam M.; LeGates, Tara A.; Cai, Xiang

    2015-01-01

    Depression is a common cause of mortality and morbidity, but the biological bases of the deficits in emotional and cognitive processing remain incompletely understood. Current antidepressant therapies are effective in only some patients and act slowly. We propose an excitatory synapse hypothesis of depression in which chronic stress and genetic susceptibility cause changes in the strength of subsets of glutamatergic synapses at multiple locations, including the prefrontal cortex, hippocampus and nucleus accumbens, leading to a dysfunction of cortico-mesolimbic reward circuitry that underlies many of the symptoms of depression. This hypothesis accounts for current depression treatments and suggests an updated framework for the development of better therapeutic compounds. PMID:25887240

  4. Response to enemies in the invasive plant Lythrum salicaria is genetically determined

    PubMed Central

    Joshi, Srijana; Tielbörger, Katja

    2012-01-01

    Background and Aims The enemy release hypothesis assumes that invasive plants lose their co-evolved natural enemies during introduction into the new range. This study tested, as proposed by the evolution of increased competitive ability (EICA) hypothesis, whether escape from enemies results in a decrease in defence ability in plants from the invaded range. Two straightforward aspects of the EICA are examined: (1) if invasives have lost their enemies and their defence, they should be more negatively affected by their full natural pre-invasion herbivore spectrum than their native conspecifics; and (2) the genetic basis of evolutionary change in response to enemy release in the invasive range has not been taken sufficiently into account. Methods Lythrum salicaria (purple loosestrife) from several populations in its native (Europe) and invasive range (North America) was exposed to all above-ground herbivores in replicated natural populations in the native range. The experiment was performed both with plants raised from field-collected seeds as well as with offspring of these where maternal effects were removed. Key Results Absolute and relative leaf damage was higher for introduced than for native plants. Despite having smaller height growth rate, invasive plants attained a much larger final size than natives irrespective of damage, indicating large tolerance rather than effective defence. Origin effects on response to herbivory and growth were stronger in second-generation plants, suggesting that invasive potential through enemy release has a genetic basis. Conclusions The findings support two predictions of the EICA hypothesis – a genetically determined difference between native and invasive plants in plant vigour and response to enemies – and point to the importance of experiments that control for maternal effects and include the entire spectrum of native range enemies. PMID:22492331

  5. Priming Ability Emotional Intelligence

    ERIC Educational Resources Information Center

    Schutte, Nicola S.; Malouff, John M.

    2012-01-01

    Two studies examined whether priming self-schemas relating to successful emotional competency results in better emotional intelligence performance. In the first study participants were randomly assigned to a successful emotional competency self-schema prime condition or a control condition and then completed an ability measure of emotional…

  6. Transformation Problem Solving Abilities.

    ERIC Educational Resources Information Center

    Harmel, Sarah Jane

    The relationship between transformation problem performance and Guilford Structure of Intellect (SI) abilities is explored. During two group sessions 42 females and 35 males, age 18-39, were administered 12 Guilford SI tests exemplifying all five symbolic content (numeric) operations, and three contents in the divergent production area. Logical…

  7. Conservatism and Cognitive Ability

    ERIC Educational Resources Information Center

    Stankov, Lazar

    2009-01-01

    Conservatism and cognitive ability are negatively correlated. The evidence is based on 1254 community college students and 1600 foreign students seeking entry to United States' universities. At the individual level of analysis, conservatism scores correlate negatively with SAT, Vocabulary, and Analogy test scores. At the national level of…

  8. Measuring Divergent Abilities.

    ERIC Educational Resources Information Center

    Sefer, Jasmina

    The validity and reliability of the Yugoslavian (Beograd) version of the Hungarian adaptation of the Torrance Divergent Capacities Test (HAT-DAT) were tested, with a view toward improving the methodology of scoring the creative abilities test and determining standards for Yugoslavia. The test, based on the work of J. P. Guilford (1977), examines…

  9. A Specific Calculating Ability.

    ERIC Educational Resources Information Center

    Anderson, Mike; O'Connor, Neil; Hermelin, Beate

    1998-01-01

    Studied the calculating ability used by a low IQ savant to identify prime numbers in two experiments comparing him to control subjects, one involving reaction time and the other involving inspection time. Concludes that this individual uses a complex computational algorithm to identify primes and discusses the apparent contradiction of his low IQ.…

  10. Forty Years Later: Updating the Fossilization Hypothesis

    ERIC Educational Resources Information Center

    Han, ZhaoHong

    2013-01-01

    A founding concept in second language acquisition (SLA) research, fossilization has been fundamental to understanding second language (L2) development. The Fossilization Hypothesis, introduced in Selinker's seminal text (1972), has thus been one of the most influential theories, guiding a significant bulk of SLA research for four decades; 2012…

  11. Empagliflozin's Fuel Hypothesis: Not so Soon.

    PubMed

    Lopaschuk, Gary D; Verma, Subodh

    2016-08-01

    The EMPA-REG OUTCOME trial (Zinman et al., 2015) established cardioprotective effects of empagliflozin in high-risk diabetic patients, but the underlying mechanisms remain elusive. A recent hypothesis proposed that increased ketone oxidation contributed to the effect, but several caveats indicate that the role of myocardial ketone oxidation is far from clear. PMID:27508868

  12. A new hypothesis on HIV cure

    PubMed Central

    Hladik, Florian

    2015-01-01

    In this opinion article, I provide the rationale for my hypothesis that nucleoside reverse transcriptase inhibitors (NRTIs) may prevent human immunodeficiency virus (HIV) cure by promoting the survival of cells with integrated provirus. If correct, we may be closer to a cure than we realize. PMID:26380071

  13. A Developmental Study of the Infrahumanization Hypothesis

    ERIC Educational Resources Information Center

    Martin, John; Bennett, Mark; Murray, Wayne S.

    2008-01-01

    Intergroup attitudes in children were examined based on Leyen's "infrahumanization hypothesis". This suggests that some uniquely human emotions, such as shame and guilt (secondary emotions), are reserved for the in-group, whilst other emotions that are not uniquely human and shared with animals, such as anger and pleasure (primary emotions), are…

  14. Pathogenesis of Rushton bodies: A novel hypothesis.

    PubMed

    Sarode, Gargi S; Sarode, Sachin C; Tupkari, Jagdish V; Deshmukh, Revati; Patil, Shankargouda

    2016-08-01

    Rushton bodies (RBs) are one of the characteristic features seen in the epithelial lining of odontogenic cysts mainly radicular, dentigerous and odontogenic keratocyst. It has two different histo-morphological appearances; granular and homogeneous. Although widely investigated, the exact pathogenesis and histogenesis of RBs is still an enigma. Many hypotheses were made in the literature but none has explained conceivably the two histo-morphological appearances of RBs and their association with inflammation. In the present paper the various pathogenesis for the formation of RBs proposed till date are discussed along with proposal for a novel hypothesis. The given hypothesis is mainly related to inflammation and its effect on pore size of basement membrane of odontogenic cystic epithelium. It explains RBs association with inflammation as well as existence of two histo-morphological appearances. The proposed hypothesis also justifies the RB's presence inside the lining epithelium of odontogenic cyst despite its hematogenous origin. Future studies are advocated for isolating RBs using laser capture microdissection and subsequent biochemical, histochemical and electron microscopic analysis to substantiate the proposed hypothesis. PMID:27372880

  15. The Marathon Group Hypothesis: An Unanswered Question

    ERIC Educational Resources Information Center

    Marks, Stephen E.; And Others

    1973-01-01

    The authors of this article contend that the Guinan and Foulds study was inadequately designed and executed, and the results indicate little of the "usefulness" of the test, much less illuminate the important hypothesis central to the investigation. Specific suggestions for further research in marathon group evaluation are made. (Author)

  16. A Philosophical Critique of Null Hypothesis Testing.

    ERIC Educational Resources Information Center

    Orey III, Michael A.; And Others

    1989-01-01

    An attempt is made to clarify the philosophical foundations of the debate over research methodology appropriate for psychology in particular and the utility of null hypothesis testing in general. The article also relates the debate to education and suggests that the debate is far from settled. (IAH)

  17. Egocentrism and Peer Interaction: Testing Piaget's Hypothesis.

    ERIC Educational Resources Information Center

    French, Doran; And Others

    This experiment tested Piaget's hypothesis that peer interaction plays a crucial role in the reduction of childhood egocentrism. A sample of 46 second graders from a middle-class suburban public school were given a sociometric measure of popularity. Four tasks which assessed spatial, communicative, and role-taking egocentrism were then performed…

  18. Hypothesis on the nature of atmospheric UFOs

    NASA Astrophysics Data System (ADS)

    Mukharev, L. A.

    1991-08-01

    A hypothesis is developed according to which the atmospheric UFO phenomenon has an electromagnetic nature. It is suggested that an atmospheric UFO is an agglomeration of charged atmospheric dust within which there exists a slowly damped electromagnetic field. This field is considered to be the source of the observed optical effects and the motive force of the UFO.

  19. Morbidity and Infant Development: A Hypothesis.

    ERIC Educational Resources Information Center

    Pollitt, Ernesto

    1983-01-01

    Results of a study conducted in 14 villages of Sui Lin Township, Taiwan, suggest the hypothesis that, under conditions of extreme economic impoverishment and among children within populations where energy protein malnutrition is endemic, there is an inverse relationship between incidence of morbidity in infancy and measures of motor and mental…

  20. Groupthink: Hypothesis in Need of Testing.

    ERIC Educational Resources Information Center

    Moorhead, Gregory

    1982-01-01

    Reviews the major tenets of the groupthink hypothesis of Irving Janis, as well as the research on which it is based. Reviews previous research on group dynamics related to groupthink. Proposes guidelines for research to test the propositions of groupthink. (Author/RC)

  1. In Defense of Chi's Ontological Incompatibility Hypothesis

    ERIC Educational Resources Information Center

    Slotta, James D.

    2011-01-01

    This article responds to an article by A. Gupta, D. Hammer, and E. F. Redish (2010) that asserts that M. T. H. Chi's (1992, 2005) hypothesis of an "ontological commitment" in conceptual development is fundamentally flawed. In this article, I argue that Chi's theoretical perspective is still very much intact and that the critique offered by Gupta…

  2. The Hypothesis of Incommensurability and Multicultural Education

    ERIC Educational Resources Information Center

    McDonough, Tim

    2009-01-01

    This article describes the logical and rhetorical grounds for a multicultural pedagogy that teaches students the knowledge and skills needed to interact creatively in the public realm betwixt and between cultures. I begin by discussing the notion of incommensurability. I contend that this hypothesis was intended to perform a particular rhetorical…

  3. The Antieconomy Hypothesis (Part 2): Theoretical Roots

    ERIC Educational Resources Information Center

    Vanderburg, Willem H.

    2009-01-01

    The hypothesis of an antieconomy developed in part 1 is incommensurate with mainstream economics. This article explores three reasons for this situation: the limits of discipline-based scholarship in general and of mainstream economics in particular, the status of economists in contemporary societies, and the failure of economists to accept any…

  4. Einstein's Revolutionary Light-Quantum Hypothesis

    NASA Astrophysics Data System (ADS)

    Stuewer, Roger H.

    2005-05-01

    The paper in which Albert Einstein proposed his light-quantum hypothesis was the only one of his great papers of 1905 that he himself termed ``revolutionary.'' Contrary to widespread belief, Einstein did not propose his light-quantum hypothesis ``to explain the photoelectric effect.'' Instead, he based his argument for light quanta on the statistical interpretation of the second law of thermodynamics, with the photoelectric effect being only one of three phenomena that he offered as possible experimental support for it. I will discuss Einstein's light-quantum hypothesis of 1905 and his introduction of the wave-particle duality in 1909 and then turn to the reception of his work on light quanta by his contemporaries. We will examine the reasons that prominent physicists advanced to reject Einstein's light-quantum hypothesis in succeeding years. Those physicists included Robert A. Millikan, even though he provided convincing experimental proof of the validity of Einstein's equation of the photoelectric effect in 1915. The turning point came after Arthur Holly Compton discovered the Compton effect in late 1922, but even then Compton's discovery was contested both on experimental and on theoretical grounds. Niels Bohr, in particular, had never accepted the reality of light quanta and now, in 1924, proposed a theory, the Bohr-Kramers-Slater theory, which assumed that energy and momentum were conserved only statistically in microscopic interactions. Only after that theory was disproved experimentally in 1925 was Einstein's revolutionary light-quantum hypothesis generally accepted by physicists---a full two decades after Einstein had proposed it.

  5. Do the Brain Networks of Scientists Account for Their Superiority in Hypothesis-Generating?

    ERIC Educational Resources Information Center

    Lee, Jun-Ki

    2012-01-01

    Where do scientists' superior abilities originate from when generating a creative idea? What different brain functions are activated between scientists and i) general academic high school students and ii) science high school students when generating a biological hypothesis? To reveal brain level explanations for these questions, this paper…

  6. Modeling Reader and Text Interactions during Narrative Comprehension: A Test of the Lexical Quality Hypothesis

    ERIC Educational Resources Information Center

    Hamilton, Stephen T.; Freed, Erin M.; Long, Debra L.

    2013-01-01

    The goal of this study was to examine predictions derived from the Lexical Quality Hypothesis regarding relations among word decoding, working-memory capacity, and the ability to integrate new concepts into a developing discourse representation. Hierarchical Linear Modeling was used to quantify the effects of three text properties (length,…

  7. The GAIA Hypothesis and Chaos in Daisyworld.

    NASA Astrophysics Data System (ADS)

    Flynn, Cathal Michael

    1993-01-01

    To correctly model the climate it is necessary to include the effects of the biosphere. The Gaia hypothesis claims that the earth's living matter, air, oceans, and land form a complex system which has the capacity to regulate the earth's climate. A model developed by Lovelock and Watson to demonstrate the Gaia hypothesis is explained and the results of their work are reviewed. Only steady state behavior is observed in the Daisyworld model. The work of Zeng et al. on the presence of chaos in Daisyworld is reviewed as an introduction to our own work. The presence of oscillatory and even chaotic behavior in this Daisyworld model brings into question the Gaia hypothesis. We develop a model of two-dimensional crystal growth called Crystalworld. The Crystalworld model is similar to the Daisyworld model in that there is a coupling between the growing entities and their environment via temperature. The results of this model are similar to that of the Daisyworld model. We present the results of another modified model of Daisyworld which we developed. This modified model takes into account the finite response time of the daisies to changes in the planet's climatic conditions. With a generation time introduced into the model equations, while retaining the differential equation format, it is found that the system can show oscillatory and chaotic behavior. These results show that any climate-biosphere model must contain a time delay and that such a time delay leads to behavior which contradicts the Gaia hypothesis. In order to determine the effects of introducing more species we develop a model with two species of daisies and a parasite species. For this Parasite-Daisyworld model steady state, periodic and chaotic behavior is found. A comparison between the results of this model and that of Zeng et al. is made. The results of the Parasite-Daisyworld model show that increasing the number of species does not lead to increased regulation. This contradicts the Gaia hypothesis and

  8. Are invasive plants more competitive than native conspecifics? Patterns vary with competitors.

    PubMed

    Zheng, Yulong; Feng, Yulong; Valiente-Banuet, Alfonso; Li, Yangping; Liao, Zhiyong; Zhang, Jiaolin; Chen, Yajun

    2015-01-01

    Invasive plants are sometimes considered to be more competitive than their native conspecifics, according to the prediction that the invader reallocates resources from defense to growth due to liberation of natural enemies ['Evolution of Increased Competitive Ability' (EICA) hypothesis]. However, the differences in competitive ability may depend on the identity of competitors. In order to test the effects of competitors, Ageratina adenophora plants from both native and invasive ranges competed directly, and competed with native residents from both invasive (China) and native (Mexico) ranges respectively. Invasive A. adenophora plants were more competitive than their conspecifics from native populations when competing with natives from China (interspecific competition), but not when competing with natives from Mexico. Invasive A. adenophora plants also showed higher competitive ability when grown in high-density monoculture communities of plants from the same population (intrapopulation competition). In contrast, invasive A. adenophora plants showed lower competitive ability when competing with plants from native populations (intraspecific competition). Our results indicated that in the invasive range A. adenophora has evolved to effectively cope with co-occurring natives and high density environments, contributing to invasion success. Here, we showed the significant effects of competitors, which should be considered carefully when testing the EICA hypothesis. PMID:26489964

  9. Tests of the Giant Impact Hypothesis

    NASA Technical Reports Server (NTRS)

    Jones, J. H.

    1998-01-01

    The giant impact hypothesis has gained popularity as a means of explaining a volatile-depleted Moon that still has a chemical affinity to the Earth. As Taylor's Axiom decrees, the best models of lunar origin are testable, but this is difficult with the giant impact model. The energy associated with the impact would be sufficient to totally melt and partially vaporize the Earth. And this means that there should he no geological vestige of Barber times. Accordingly, it is important to devise tests that may be used to evaluate the giant impact hypothesis. Three such tests are discussed here. None of these is supportive of the giant impact model, but neither do they disprove it.

  10. Testing the Markov hypothesis in fluid flows

    NASA Astrophysics Data System (ADS)

    Meyer, Daniel W.; Saggini, Frédéric

    2016-05-01

    Stochastic Markov processes are used very frequently to model, for example, processes in turbulence and subsurface flow and transport. Based on the weak Chapman-Kolmogorov equation and the strong Markov condition, we present methods to test the Markov hypothesis that is at the heart of these models. We demonstrate the capabilities of our methodology by testing the Markov hypothesis for fluid and inertial particles in turbulence, and fluid particles in the heterogeneous subsurface. In the context of subsurface macrodispersion, we find that depending on the heterogeneity level, Markov models work well above a certain scale of interest for media with different log-conductivity correlation structures. Moreover, we find surprising similarities in the velocity dynamics of the different media considered.

  11. Crohn's disease: the cold chain hypothesis.

    PubMed

    Forbes, Alastair; Kalantzis, Tommy

    2006-07-01

    A recent published hypothesis proposed that Crohn's disease was provoked by infantile exposure to micro-organisms that can survive refrigerator temperature. A case-control study was accordingly devised. The mean age at first fridge was 5.6 years amongst 88 patients with Crohn's disease, 5.5 years in 88 patients with ulcerative colitis (UC) and 7.6 years in 88 controls, but a majority of individuals had always been exposed to refrigerated food. Differences were more striking in subjects aged above the median (10.3, 10.9 and 15.0 years for Crohn's disease, UC and controls, respectively). This support for the hypothesis reached statistical significance for those with Crohn's disease compared to the controls (p=0.045). PMID:16059694

  12. The Neural Rejuvenation Hypothesis of Cocaine Addiction

    PubMed Central

    Dong, Yan; Nestler, Eric J.

    2014-01-01

    A leading hypothesis guiding current molecular and cellular research of drug addiction conceptualizes key aspects of addiction as a form of memory, in which common neuroplasticity mechanisms that mediate normal learning and memory processes are “hijacked” by exposure to drugs of abuse to produce pathologic addiction-related memories. Such addiction-related memories are particularly robust and long-lasting and once formed, less amenable to updating. Here, we propose the Neural Rejuvenation Hypothesis of Cocaine Addiction: that repeated exposure to drugs of abuse induces some plasticity mechanisms that are normally associated with brain development within the brain’s reward circuitry, which mediate the highly efficient and unusually stable memory abnormalities that characterize addiction. PMID:24958329

  13. Exploring heterogeneous market hypothesis using realized volatility

    NASA Astrophysics Data System (ADS)

    Chin, Wen Cheong; Isa, Zaidi; Mohd Nor, Abu Hassan Shaari

    2013-04-01

    This study investigates the heterogeneous market hypothesis using high frequency data. The cascaded heterogeneous trading activities with different time durations are modelled by the heterogeneous autoregressive framework. The empirical study indicated the presence of long memory behaviour and predictability elements in the financial time series which supported heterogeneous market hypothesis. Besides the common sum-of-square intraday realized volatility, we also advocated two power variation realized volatilities in forecast evaluation and risk measurement in order to overcome the possible abrupt jumps during the credit crisis. Finally, the empirical results are used in determining the market risk using the value-at-risk approach. The findings of this study have implications for informationally market efficiency analysis, portfolio strategies and risk managements.

  14. A hypothesis for delayed dynamic earthquake triggering

    USGS Publications Warehouse

    Parsons, T.

    2005-01-01

    It's uncertain whether more near-field earthquakes are triggered by static or dynamic stress changes. This ratio matters because static earthquake interactions are increasingly incorporated into probabilistic forecasts. Recent studies were unable to demonstrate all predictions from the static-stress-change hypothesis, particularly seismicity rate reductions. However, current dynamic stress change hypotheses do not explain delayed earthquake triggering and Omori's law. Here I show numerically that if seismic waves can alter some frictional contacts in neighboring fault zones, then dynamic triggering might cause delayed triggering and an Omori-law response. The hypothesis depends on faults following a rate/state friction law, and on seismic waves changing the mean critical slip distance (Dc) at nucleation zones.

  15. Geochemical confirmation of the lunar magmasphere hypothesis

    NASA Technical Reports Server (NTRS)

    Warren, P. H.

    1985-01-01

    The lunar magmasphere (or magma ocean) hypothesis was originally conceived to account for the enrichment of cumulus plagioclase (Al and Ca) in the main (highlands) portion of the crust. The great age of the highlands, and the complementary pattern of Eu anomalies between the highlands and the younger mare basalts, helped convince most specialists that the magmasphere hypothesis is correct. Doubts persist, however, particularly among physicists concerned about heat sources. It was shown in 1976 that a plot of Na/Ca vs. Mg/Fe for pristine highlands cumulates manifests a profound bimodality: One group, the Mg-rich rocks, plots along a normal igneous trend of inverse correlation between Na/Ca and Mg/Fe; the other group, the ferroan anorthosites (FAN), features low Na/Ca and low Mg/Fe. Only the FAN group can be plausibly linked to plag. flotation over the magmasphere.

  16. Roger Sperry and his chemoaffinity hypothesis.

    PubMed

    Meyer, R L

    1998-10-01

    In the early 1940s, Roger Sperry performed a series of insightful experiments on the visual system of lower vertebrates that led him to draw two important conclusions: When optic fibers were severed, the regenerating fibers grew back to their original loci in the midbrain tectum to re-establish a topographical set of connections; and the re-establishment of these orderly connections underlay the orderly behavior of the animal. From these conclusions, he inferred that each optic fiber and each tectal neuron possessed cytochemical labels that uniquely denoted their neuronal type and position and that optic fibers could utilize these labels to selectively navigate to their matching target cell. This inference was subsequently formulated into a general explanation of how neurons form ordered interconnections during development and became known as the chemoaffinity hypothesis. The origins of this hypothesis, the controversies that surrounded it for several decades and its eventual acceptance, are discussed in this article. PMID:9845045

  17. Apomorphine and the dopamine hypothesis of schizophrenia: a dilemma?

    PubMed Central

    Dépatie, L; Lal, S

    2001-01-01

    The dopamine (DA) hypothesis of schizophrenia implicates an enhancement of DA function in the pathophysiology of the disorder, at least in the genesis of positive symptoms. Accordingly, apomorphine, a directly acting DA receptor agonist, should display psychotomimetic properties. A review of the literature shows little or no evidence that apomorphine, in doses that stimulate postsynaptic DA receptors, induces psychosis in non-schizophrenic subjects or a relapse or exacerbation of psychotic symptoms in patients with schizophrenia. After a detailed review of the literature reporting psychotogenic effects of apomorphine in patients with Parkinson's disease, an interpretation of these data is difficult, in part because of several confounding factors, such as the concomitant use of drugs known to induce psychosis and the advanced state of the progressive neurological disorder. In the context of the DA hypothesis of schizophrenia, the limited ability of apomorphine to induce psychosis, in contrast to indirectly acting DA agonists that increase synaptic DA, may be explained by the relatively weak affinity of apomorphine for the D3 receptor compared with DA. Alternatively, enhancement of DA function, though necessary, may be insufficient by itself to induce psychosis. PMID:11394190

  18. Large numbers hypothesis. I - Classical formalism

    NASA Technical Reports Server (NTRS)

    Adams, P. J.

    1982-01-01

    A self-consistent formulation of physics at the classical level embodying Dirac's large numbers hypothesis (LNH) is developed based on units covariance. A scalar 'field' phi(x) is introduced and some fundamental results are derived from the resultant equations. Some unusual properties of phi are noted such as the fact that phi cannot be the correspondence limit of a normal quantum scalar field.

  19. Testing the single-state dominance hypothesis

    SciTech Connect

    Álvarez-Rodríguez, R.; Moreno, O.; Moya de Guerra, E.; Sarriguren, P.; Šimkovic, F.; Faessler, A.

    2013-12-30

    We present a theoretical analysis of the single-state dominance hypothesis for the two-neutrino double-beta decay process. The theoretical framework is a proton-neutron QRPA based on a deformed Hartree-Fock mean field with BCS pairing correlations. We focus on the decays of {sup 100}Mo, {sup 116}Cd and {sup 128}Te. We do not find clear evidences for single-state dominance within the present approach.

  20. Sea otter health: challenging a pet hypothesis

    USGS Publications Warehouse

    Lafferty, Kevin D.

    2015-01-01

    A recent series of studies on tagged sea otters (Enhydra lutris nereis) challenges the hypothesis that sea otters are sentinels of a dirty ocean, in particular, that pet cats are the main source of exposure to Toxoplasma gondii in central California. Counter to expectations, sea otters from unpopulated stretches of coastline are less healthy and more exposed to parasites than city-associated otters. Ironically, now it seems that spillover from wildlife, not pets, dominates spatial patterns of disease transmission.

  1. Sea otter health: Challenging a pet hypothesis

    PubMed Central

    Lafferty, Kevin D.

    2015-01-01

    A recent series of studies on tagged sea otters (Enhydra lutris nereis) challenges the hypothesis that sea otters are sentinels of a dirty ocean, in particular, that pet cats are the main source of exposure to Toxoplasma gondii in central California. Counter to expectations, sea otters from unpopulated stretches of coastline are less healthy and more exposed to parasites than city-associated otters. Ironically, now it seems that spillover from wildlife, not pets, dominates spatial patterns of disease transmission. PMID:26155464

  2. Sea otter health: Challenging a pet hypothesis.

    PubMed

    Lafferty, Kevin D

    2015-12-01

    A recent series of studies on tagged sea otters (Enhydra lutris nereis) challenges the hypothesis that sea otters are sentinels of a dirty ocean, in particular, that pet cats are the main source of exposure to Toxoplasma gondii in central California. Counter to expectations, sea otters from unpopulated stretches of coastline are less healthy and more exposed to parasites than city-associated otters. Ironically, now it seems that spillover from wildlife, not pets, dominates spatial patterns of disease transmission. PMID:26155464

  3. Kelvin on an old, celebrated hypothesis

    NASA Astrophysics Data System (ADS)

    Harrison, Edward

    1986-07-01

    Lord Kelvin in 1901 tested an ``old and celebrated hypothesis'' that if we could see far enough into space the whole sky would be occupied with stellar disks all of perhaps the same brightness as the Sun. Kelvin was the first to solve quantitatively and correctly the riddle of a dark night sky, a riddle that had been previously solved qualitatively by Edgar Allan Poe, and is now known as Olbers' paradox.

  4. An impact hypothesis for Venus argon anomalies

    NASA Astrophysics Data System (ADS)

    Kaula, W. M.; Newman, W. I.

    1997-03-01

    The Ar-36+38 argon-excess anomally of Venus has been hypothesized to have its origin in the impact of an outer solar system body of about 100-km diameter. A critical evaluation is made of this hypothesis and its competitors; it is judged that its status must for the time being remain one of 'Sherlock Holmes' type, in that something so improbable must be accepted when all alternatives are eliminated.

  5. The spline probability hypothesis density filter

    NASA Astrophysics Data System (ADS)

    Sithiravel, Rajiv; Tharmarasa, Ratnasingham; McDonald, Mike; Pelletier, Michel; Kirubarajan, Thiagalingam

    2012-06-01

    The Probability Hypothesis Density Filter (PHD) is a multitarget tracker for recursively estimating the number of targets and their state vectors from a set of observations. The PHD filter is capable of working well in scenarios with false alarms and missed detections. Two distinct PHD filter implementations are available in the literature: the Sequential Monte Carlo Probability Hypothesis Density (SMC-PHD) and the Gaussian Mixture Probability Hypothesis Density (GM-PHD) filters. The SMC-PHD filter uses particles to provide target state estimates, which can lead to a high computational load, whereas the GM-PHD filter does not use particles, but restricts to linear Gaussian mixture models. The SMC-PHD filter technique provides only weighted samples at discrete points in the state space instead of a continuous estimate of the probability density function of the system state and thus suffers from the well-known degeneracy problem. This paper proposes a B-Spline based Probability Hypothesis Density (S-PHD) filter, which has the capability to model any arbitrary probability density function. The resulting algorithm can handle linear, non-linear, Gaussian, and non-Gaussian models and the S-PHD filter can also provide continuous estimates of the probability density function of the system state. In addition, by moving the knots dynamically, the S-PHD filter ensures that the splines cover only the region where the probability of the system state is significant, hence the high efficiency of the S-PHD filter is maintained at all times. Also, unlike the SMC-PHD filter, the S-PHD filter is immune to the degeneracy problem due to its continuous nature. The S-PHD filter derivations and simulations are provided in this paper.

  6. The Constitution of Agency in Developing Lifelong Learning Ability: The "Being" Mode

    ERIC Educational Resources Information Center

    Su, Ya-Hui

    2011-01-01

    In an age of uncertainty, one of the aims of higher education is to establish lifelong learning abilities in students. However, different authors remain divided on the question of what constitutes "lifelong learning ability". This article proposes the hypothesis that the cultivation of lifelong learning abilities in higher education needs to be…

  7. Somatotropic function: the somatomedin hypothesis revisited.

    PubMed

    Etherton, T D

    2004-01-01

    The discovery in 1922 that an alkaline extract of the anterior pituitary can increase growth and change carcass composition of rats led to the discovery of growth hormone (somatotropin, ST). Since the early studies, much has been learned about the biological effects of ST. The advent of recombinant DNA technology has led to the commercial development of ST-based products for animal agriculture. Administration of porcine ST (pST) at maximally effective doses (approximately 100 microg x kg BW(-1) x d(-1)) to growing pigs for 30 to 77 d increases average daily gain approximately 10 to 20%, improves productive efficiency (i.e., the ratio of body weight gain to feed consumed) 13 to 33%, decreases lipid accretion rates by as much as approximately 80%, and stimulates protein deposition (muscle growth) by as much as 70%. These responses are associated with a decrease in feed intake of approximately 10 to 15%. The effects of ST are mediated directly and indirectly. The indirect effects of ST are mediated by the somatomedin (insulin-like growth factor-I). The discovery of somatomedin led to the introduction of the somatomedin hypothesis, which explained the basis of ST action. Since the discovery of the somatomedins, there have been several modifications of the hypothesis developed to accommodate the evolution in understanding of how ST and IGF-I affect a diverse array of biological events. This review will summarize the history of ST and the evolution of the somatomedin hypothesis. PMID:15471803

  8. A test of the orthographic recoding hypothesis

    NASA Astrophysics Data System (ADS)

    Gaygen, Daniel E.

    2003-04-01

    The Orthographic Recoding Hypothesis [D. E. Gaygen and P. A. Luce, Percept. Psychophys. 60, 465-483 (1998)] was tested. According to this hypothesis, listeners recognize spoken words heard for the first time by mapping them onto stored representations of the orthographic forms of the words. Listeners have a stable orthographic representation of words, but no phonological representation, when those words have been read frequently but never heard or spoken. Such may be the case for low frequency words such as jargon. Three experiments using visually and auditorily presented nonword stimuli tested this hypothesis. The first two experiments were explicit tests of memory (old-new tests) for words presented visually. In the first experiment, the recognition of auditorily presented nonwords was facilitated when they previously appeared on a visually presented list. The second experiment was similar, but included a concurrent articulation task during a visual word list presentation, thus preventing covert rehearsal of the nonwords. The results were similar to the first experiment. The third experiment was an indirect test of memory (auditory lexical decision task) for visually presented nonwords. Auditorily presented nonwords were identified as nonwords significantly more slowly if they had previously appeared on the visually presented list accompanied by a concurrent articulation task.

  9. Hydrologoclimatic hypothesis and examples of its use

    SciTech Connect

    Mezentsev, V.S.

    1995-05-01

    According to the opinion of a number of specialists, relative stability of the global climate has been observed throughout approximately the last eight millennia. This statement is based on the virtually constant water level of the ocean during the above period. and data on isotopic content of some chemical elements in core samples from ultradeep bore holes in the ice sheets of Antarctica, Greenland, and other places. This raises the hypothesis, according to which a universal proportionality of the heat and water resources actively participating in the exchange processes in the hydrosphere and the atmosphere of the earth should be maintained if a relatively stable global climate is retained for eight thousand years. A probable approach to justify a hydrologoclimatic hypothesis using information on the world water balance and assuming relatively stable climatic conditions is discussed. This hypothesis allows us to more properly estimate the world water balance and ratio of heat and water resources taking an active part in their exchange, as well as to analyze and generalize the available data on climatic elements, and to update their magnitudes and ratios.

  10. Mentalizing Abilities in Preadolescents' and Their Mothers' Autobiographical Narratives

    ERIC Educational Resources Information Center

    Scopesi, Alda M.; Rosso, Anna Maria; Viterbori, Paola; Panchieri, Erika

    2015-01-01

    This study aims to investigate the association between the mental state talk of mothers and their preadolescent children, with the hypothesis that an intergenerational transmission of mentalizing abilities may extend beyond early childhood. The participants were 41 mother-preadolescent child nonclinical dyads. The Adult Attachment Interview (AAI)…

  11. An Investigation of Syntactic Abilities in Normal and Dyslexic Children.

    ERIC Educational Resources Information Center

    Vogel, Susan Ann

    Syntactic abilities in oral language of twenty normal and twenty dyslexic second grade boys were investigated. The major hypothesis was that dyslexic children with reading comprehension difficulties are deficient in oral syntax. The concept of syntax was subdivided into five categories: (1) recognition of melody pattern, (2) recognition of…

  12. Cognitive differences between orang-utan species: a test of the cultural intelligence hypothesis

    PubMed Central

    Forss, Sofia I. F.; Willems, Erik; Call, Josep; van Schaik, Carel P.

    2016-01-01

    Cultural species can - or even prefer to - learn their skills from conspecifics. According to the cultural intelligence hypothesis, selection on underlying mechanisms not only improves this social learning ability but also the asocial (individual) learning ability. Thus, species with systematically richer opportunities to socially acquire knowledge and skills should over time evolve to become more intelligent. We experimentally compared the problem-solving ability of Sumatran orang-utans (Pongo abelii), which are sociable in the wild, with that of the closely related, but more solitary Bornean orang-utans (P. pygmaeus), under the homogeneous environmental conditions provided by zoos. Our results revealed that Sumatrans showed superior innate problem-solving skills to Borneans, and also showed greater inhibition and a more cautious and less rough exploration style. This pattern is consistent with the cultural intelligence hypothesis, which predicts that the more sociable of two sister species experienced stronger selection on cognitive mechanisms underlying learning. PMID:27466052

  13. Cognitive differences between orang-utan species: a test of the cultural intelligence hypothesis.

    PubMed

    Forss, Sofia I F; Willems, Erik; Call, Josep; van Schaik, Carel P

    2016-01-01

    Cultural species can - or even prefer to - learn their skills from conspecifics. According to the cultural intelligence hypothesis, selection on underlying mechanisms not only improves this social learning ability but also the asocial (individual) learning ability. Thus, species with systematically richer opportunities to socially acquire knowledge and skills should over time evolve to become more intelligent. We experimentally compared the problem-solving ability of Sumatran orang-utans (Pongo abelii), which are sociable in the wild, with that of the closely related, but more solitary Bornean orang-utans (P. pygmaeus), under the homogeneous environmental conditions provided by zoos. Our results revealed that Sumatrans showed superior innate problem-solving skills to Borneans, and also showed greater inhibition and a more cautious and less rough exploration style. This pattern is consistent with the cultural intelligence hypothesis, which predicts that the more sociable of two sister species experienced stronger selection on cognitive mechanisms underlying learning. PMID:27466052

  14. Music and nonmusical abilities.

    PubMed

    Schellenberg, E G

    2001-06-01

    Reports that exposure to music causes benefits in nonmusical domains have received widespread attention in the mainstream media. Such reports have also influenced public policy. The so-called "Mozart effect" actually refers to two relatively distinct phenomena. One concerns short-term increases in spatial abilities that are said to occur from listening to music composed by Mozart. The other refers to the possibility that formal training in music yields nonmusical benefits. A review of the relevant findings indicates that the short-term effect is small and unreliable. Moreover, when it is evident, it can be explained by between-condition differences in the listener's mood or levels of cognitive arousal. By contrast, the effect of music lessons on nonmusical aspects of cognitive development is still an open question. Several studies have reported positive associations between formal music lessons and abilities in nonmusical (e.g., linguistic, mathematical, and spatial) domains. Nonetheless, compelling evidence for a causal link remains elusive. PMID:11458841

  15. Do Statistical Segmentation Abilities Predict Lexical-Phonological and Lexical-Semantic Abilities in Children with and without SLI?

    ERIC Educational Resources Information Center

    Mainela-Arnold, Elina; Evans, Julia L.

    2014-01-01

    This study tested the predictions of the procedural deficit hypothesis by investigating the relationship between sequential statistical learning and two aspects of lexical ability, lexical-phonological and lexical-semantic, in children with and without specific language impairment (SLI). Participants included forty children (ages 8;5-12;3), twenty…

  16. Updating the Lamellar Hypothesis of Hippocampal Organization

    PubMed Central

    Sloviter, Robert S.; Lømo, Terje

    2012-01-01

    Andersen et al. (1971) proposed that excitatory activity in the entorhinal cortex propagates topographically to the dentate gyrus, and on through a “trisynaptic circuit” lying within transverse hippocampal “slices” or “lamellae.” In this way, a relatively simple structure might mediate complex functions in a manner analogous to the way independent piano keys can produce a nearly infinite variety of unique outputs. The lamellar hypothesis derives primary support from the “lamellar” distribution of dentate granule cell axons (the mossy fibers), which innervate dentate hilar neurons and area CA3 pyramidal cells and interneurons within the confines of a thin transverse hippocampal segment. Following the initial formulation of the lamellar hypothesis, anatomical studies revealed that unlike granule cells, hilar mossy cells, CA3 pyramidal cells, and Layer II entorhinal cells all form axonal projections that are more divergent along the longitudinal axis than the clearly “lamellar” mossy fiber pathway. The existence of pathways with “translamellar” distribution patterns has been interpreted, incorrectly in our view, as justifying outright rejection of the lamellar hypothesis (Amaral and Witter, 1989). We suggest that the functional implications of longitudinally projecting axons depend not on whether they exist, but on what they do. The observation that focal granule cell layer discharges normally inhibit, rather than excite, distant granule cells suggests that longitudinal axons in the dentate gyrus may mediate “lateral” inhibition and define lamellar function, rather than undermine it. In this review, we attempt a reconsideration of the evidence that most directly impacts the physiological concept of hippocampal lamellar organization. PMID:23233836

  17. Are invasive plants more competitive than native conspecifics? Patterns vary with competitors

    PubMed Central

    Zheng, Yulong; Feng, Yulong; Valiente-Banuet, Alfonso; Li, Yangping; Liao, Zhiyong; Zhang, Jiaolin; Chen, Yajun

    2015-01-01

    Invasive plants are sometimes considered to be more competitive than their native conspecifics, according to the prediction that the invader reallocates resources from defense to growth due to liberation of natural enemies [‘Evolution of Increased Competitive Ability’ (EICA) hypothesis]. However, the differences in competitive ability may depend on the identity of competitors. In order to test the effects of competitors, Ageratina adenophora plants from both native and invasive ranges competed directly, and competed with native residents from both invasive (China) and native (Mexico) ranges respectively. Invasive A. adenophora plants were more competitive than their conspecifics from native populations when competing with natives from China (interspecific competition), but not when competing with natives from Mexico. Invasive A. adenophora plants also showed higher competitive ability when grown in high-density monoculture communities of plants from the same population (intrapopulation competition). In contrast, invasive A. adenophora plants showed lower competitive ability when competing with plants from native populations (intraspecific competition). Our results indicated that in the invasive range A. adenophora has evolved to effectively cope with co-occurring natives and high density environments, contributing to invasion success. Here, we showed the significant effects of competitors, which should be considered carefully when testing the EICA hypothesis. PMID:26489964

  18. Are invasive plants more competitive than native conspecifics? Patterns vary with competitors

    NASA Astrophysics Data System (ADS)

    Zheng, Yulong; Feng, Yulong; Valiente-Banuet, Alfonso; Li, Yangping; Liao, Zhiyong; Zhang, Jiaolin; Chen, Yajun

    2015-10-01

    Invasive plants are sometimes considered to be more competitive than their native conspecifics, according to the prediction that the invader reallocates resources from defense to growth due to liberation of natural enemies [‘Evolution of Increased Competitive Ability’ (EICA) hypothesis]. However, the differences in competitive ability may depend on the identity of competitors. In order to test the effects of competitors, Ageratina adenophora plants from both native and invasive ranges competed directly, and competed with native residents from both invasive (China) and native (Mexico) ranges respectively. Invasive A. adenophora plants were more competitive than their conspecifics from native populations when competing with natives from China (interspecific competition), but not when competing with natives from Mexico. Invasive A. adenophora plants also showed higher competitive ability when grown in high-density monoculture communities of plants from the same population (intrapopulation competition). In contrast, invasive A. adenophora plants showed lower competitive ability when competing with plants from native populations (intraspecific competition). Our results indicated that in the invasive range A. adenophora has evolved to effectively cope with co-occurring natives and high density environments, contributing to invasion success. Here, we showed the significant effects of competitors, which should be considered carefully when testing the EICA hypothesis.

  19. The regulation of the air: a hypothesis

    NASA Astrophysics Data System (ADS)

    Nisbet, E. G.; Fowler, C. M. R.; Nisbet, R. E. R.

    2011-09-01

    We propose the hypothesis that natural selection, acting on the specificity of rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) for carbon dioxide over oxygen, has controlled the CO2:O2 ratio of the atmosphere since the evolution of photosynthesis and has also sustained the Earth's greenhouse-set surface temperature. Rubisco works in partnership with the nitrogen-fixing enzyme nitrogenase to control atmospheric pressure. Together, these two enzymes control global surface temperature and indirectly the pH and oxygenation of the ocean. Thus, the co-evolution of these two enzymes may have produced clement conditions on the Earth's surface, allowing life to be sustained.

  20. Psychopathy in youth and intelligence: an investigation of Cleckley's hypothesis.

    PubMed

    Salekin, Randall T; Neumann, Craig S; Leistico, Anne-Marie R; Zalot, Alecia A

    2004-12-01

    Cleckley (1941) hypothesized that true or "primary" psychopathic individuals have "good" intelligence. This study examined the relation between psychopathy and intelligence in 122 detained children and adolescents. We used the Psychopathy Checklist-Youth Version (PCL-YV; Forth, Kosson, & Hare, 2003) to assess psychopathy and administered novel intelligence measures to tap diverse interpretations of the intelligence construct (e.g., traditional and triarchic intelligence). Structural equation modeling indicated that dimensions of psychopathy and intelligence were related in unique and important ways. In particular, psychopathy traits reflecting a superficial and deceitful interpersonal style were positively related to intellectual skills in the verbal realm (Kaufman's Brief Intelligence Test [K-BIT]; Kaufman & Kaufman, 1990) and a nontraditional intellectual measure reflecting creativity, practicality, and analytic thinking as measured by Sternberg's Triarchic Abilities Test (STAT; Sternberg, 1993). Finally, the results also suggested that psychopathy traits reflecting disturbances in affective processing were inversely associated with verbal intellectual abilities. Thus, Cleckley's hypothesis was partially supported by the data, when taking into account the facets of psychopathy and when examining intelligence from the perspective of traditional and more novel and contemporary intellectual models. PMID:15498740

  1. Learning-Related Changes in Adolescents' Neural Networks during Hypothesis-Generating and Hypothesis-Understanding Training

    ERIC Educational Resources Information Center

    Lee, Jun-Ki; Kwon, Yongju

    2012-01-01

    Fourteen science high school students participated in this study, which investigated neural-network plasticity associated with hypothesis-generating and hypothesis-understanding in learning. The students were divided into two groups and participated in either hypothesis-generating or hypothesis-understanding type learning programs, which were…

  2. Modeling Reader- and Text- Interactions During Narrative Comprehension: A Test of the Lexical Quality Hypothesis

    PubMed Central

    Hamilton, Stephen T.; Freed, Erin M.; Long, Debra L.

    2013-01-01

    The goal of this study was to examine predictions derived from the Lexical Quality Hypothesis (Perfetti & Hart, 2002; Perfetti, 2007) regarding relations among word-decoding, working-memory capacity, and the ability to integrate new concepts into a developing discourse representation. Hierarchical Linear Modeling was used to quantify the effects of two text properties (length and number of new concepts) on reading times of focal and spillover sentences, with variance in those effects estimated as a function of individual difference factors (decoding, vocabulary, print exposure, and working-memory capacity). The analysis revealed complex, cross-level interactions that complement the Lexical Quality Hypothesis. PMID:23526862

  3. Modeling Differentiation of Cognitive Abilities within the Higher-Order Factor Model Using Moderated Factor Analysis

    ERIC Educational Resources Information Center

    Molenaar, Dylan; Dolan, Conor V.; Wicherts, Jelte M.; van der Maas, Han L. J.

    2010-01-01

    The general differentiation hypothesis states that the strength of the correlations among a set of IQ subtests varies with a given variable. Instances of the general differentiation hypothesis that have been considered in the literature include age and ability differentiation. Traditionally, the differentiation effect is attributed to the varying…

  4. Investigations into the hypothesis of transgenic cannabis.

    PubMed

    Cascini, Fidelia

    2012-05-01

    The unusual concentration of cannabinoids recently found in marijuana samples submitted to the forensic laboratory for chemical analysis prompted an investigation into whether genetic modifications have been made to the DNA of Cannabis sativa L. to increase its potency. Traditional methods for the detection of genetically modified organisms (GMO) were used to analyze herbal cannabis preparations. Our analyses support the hypothesis that marijuana samples submitted to forensic laboratories and characterized by an abnormal level of Δ(9)-THC are the product of breeding selection rather than of transgenic modifications. Further, this research has shown a risk of false positive results associated with the poor quality of the seized samples and probably due to the contamination by other transgenic vegetable products. On the other hand, based on these data, a conclusive distinction between the hypothesis of GMO plant contamination and the other of genetic modification of cannabis cannot be made requiring further studies on comparative chemical and genetic analyses to find out an explanation for the recently detected increased potency of cannabis. PMID:22211569

  5. The mitonuclear compatibility hypothesis of sexual selection.

    PubMed

    Hill, Geoffrey E; Johnson, James D

    2013-10-01

    Why females assess ornaments when choosing mates remains a central question in evolutionary biology. We hypothesize that the imperative for a choosing female to find a mate with nuclear oxidative phosphorylation (OXPHOS) genes that are compatible with her mitochondrial OXPHOS genes drives the evolution of ornaments. Indicator traits are proposed to signal the efficiency of OXPHOS function thus enabling females to select mates with nuclear genes that are compatible with maternal mitochondrial genes in the formation of OXPHOS complexes. Species-typical pattern of ornamentation is proposed to serve as a marker of mitochondrial type ensuring that females assess prospective mates with a shared mitochondrial background. The mitonuclear compatibility hypothesis predicts that the production of ornaments will be closely linked to OXPHOS pathways, and that sexual selection for compatible mates will be strongest when genes for nuclear components of OXPHOS complexes are Z-linked. The implications of this hypothesis are that sexual selection may serve as a driver for the evolution of more efficient cellular respiration. PMID:23945683

  6. Inoculation Stress Hypothesis of Environmental Enrichment

    PubMed Central

    Crofton, Elizabeth J.; Zhang, Yafang; Green, Thomas A.

    2014-01-01

    One hallmark of psychiatric conditions is the vast continuum of individual differences in susceptibility vs. resilience resulting from the interaction of genetic and environmental factors. The environmental enrichment paradigm is an animal model that is useful for studying a range of psychiatric conditions, including protective phenotypes in addiction and depression models. The major question is how environmental enrichment, a non-drug and non-surgical manipulation, can produce such robust individual differences in such a wide range of behaviors. This paper draws from a variety of published sources to outline a coherent hypothesis of inoculation stress as a factor producing the protective enrichment phenotypes. The basic tenet suggests that chronic mild stress from living in a complex environment and interacting non-aggressively with conspecifics can inoculate enriched rats against subsequent stressors and/or drugs of abuse. This paper reviews the enrichment phenotypes, mulls the fundamental nature of environmental enrichment vs. isolation, discusses the most appropriate control for environmental enrichment, and challenges the idea that cortisol/corticosterone equals stress. The intent of the inoculation stress hypothesis of environmental enrichment is to provide a scaffold with which to build testable hypotheses for the elucidation of the molecular mechanisms underlying these protective phenotypes and thus provide new therapeutic targets to treat psychiatric/neurological conditions. PMID:25449533

  7. Einstein's Revolutionary Light--Quantum Hypothesis

    NASA Astrophysics Data System (ADS)

    Stuewer, R. H.

    2006-03-01

    Albert Einstein's light-quantum paper was the only one of his great papers of 1905 that he himself called ``very revolutionary''. I sketch his arguments for light quanta, his analysis of the photoelectric effect, and his introduction of the wave-particle duality into physics in 1909. I show that Robert Andrews Millikan, in common with almost all physicists at the time, rejected Einstein's light-quantum hypothesis as an interpretation of his photoelectric-effect experiments of 1915. I then trace the complex experimental and theoretical route that Arthur Holly Compton followed between 1916 and 1922 that led to his discovery of the Compton effect, a discovery that Peter Debye also made virtually simultaneously and independently. Compton's discovery, however, was challenged on experimental grounds by William Duane and on theoretical grounds by Niels Bohr in the Bohr--Kramers--Slater theory of 1924, and only after that theory was disproved experimentally the following year by Walther Bothe and Hans Geiger in Berlin and by Compton and Alfred W. Simon in Chicago was Einstein's light-quantum hypothesis generally accepted by physicists.

  8. The Malaria-High Blood Pressure Hypothesis

    PubMed Central

    Smeeth, Liam; Cruickshank, J. Kennedy; Scott, J. Anthony G.

    2016-01-01

    Rationale: Several studies have demonstrated links between infectious diseases and cardiovascular conditions. Malaria and hypertension are widespread in many low- and middle-income countries, but the possible link between them has not been considered. Objective: In this article, we outline the basis for a possible link between malaria and hypertension and discuss how the hypothesis could be confirmed or refuted. Methods and Results: We reviewed published literature on factors associated with hypertension and checked whether any of these were also associated with malaria. We then considered various study designs that could be used to test the hypothesis. Malaria causes low birth weight, malnutrition, and inflammation, all of which are associated with hypertension in high-income countries. The hypothetical link between malaria and hypertension can be tested through the use of ecological, cohort, or Mendelian randomization studies, each of which poses specific challenges. Conclusions: Confirmation of the existence of a causative link with malaria would be a paradigm shift in efforts to prevent and control hypertension and would stimulate wider research on the links between infectious and noncommunicable disease. PMID:27151400

  9. The mitonuclear compatibility hypothesis of sexual selection

    PubMed Central

    Hill, Geoffrey E.; Johnson, James D.

    2013-01-01

    Why females assess ornaments when choosing mates remains a central question in evolutionary biology. We hypothesize that the imperative for a choosing female to find a mate with nuclear oxidative phosphorylation (OXPHOS) genes that are compatible with her mitochondrial OXPHOS genes drives the evolution of ornaments. Indicator traits are proposed to signal the efficiency of OXPHOS function thus enabling females to select mates with nuclear genes that are compatible with maternal mitochondrial genes in the formation of OXPHOS complexes. Species-typical pattern of ornamentation is proposed to serve as a marker of mitochondrial type ensuring that females assess prospective mates with a shared mitochondrial background. The mitonuclear compatibility hypothesis predicts that the production of ornaments will be closely linked to OXPHOS pathways, and that sexual selection for compatible mates will be strongest when genes for nuclear components of OXPHOS complexes are Z-linked. The implications of this hypothesis are that sexual selection may serve as a driver for the evolution of more efficient cellular respiration. PMID:23945683

  10. Cosmological Constant and the Final Anthropic Hypothesis

    NASA Astrophysics Data System (ADS)

    Ćirković, Milan M.; Bostrom, Nick

    The influence of recent detections of a finite vacuum energy (`cosmological constant') on our formulation of anthropic conjectures, particularly the so-called Final Anthropic Principle is investigated. It is shown that non-zero vacuum energy implies the onset of a quasi-exponential expansion of our causally connected domain (`the universe') at some point in the future, a stage similar to the inflationary expansion at the very beginning of time. The transition to this future inflationary phase of cosmological expansion will preclude indefinite survival of intelligent species in our domain, because of the rapid shrinking of particle horizons and subsequent depletion of energy necessary for information processes within the horizon of any observer. Therefore, to satisfy the Final Anthropic Hypothesis (reformulated to apply to the entire ensemble of universes), it is necessary to show that (i) chaotic inflation of Linde (or some similar model) provides a satisfactory description of reality, (ii) migration between causally connected domains within the multiverse is physically permitted, and (iii) the time interval left to the onset of the future inflationary phase is sufficient for development of the technology necessary for such inter-domain travel. These stringent requirements diminish the probability of the Final Anthropic Hypothesis being true.

  11. The Younger Dryas impact hypothesis: A requiem

    NASA Astrophysics Data System (ADS)

    Pinter, Nicholas; Scott, Andrew C.; Daulton, Tyrone L.; Podoll, Andrew; Koeberl, Christian; Anderson, R. Scott; Ishman, Scott E.

    2011-06-01

    The Younger Dryas (YD) impact hypothesis is a recent theory that suggests that a cometary or meteoritic body or bodies hit and/or exploded over North America 12,900 years ago, causing the YD climate episode, extinction of Pleistocene megafauna, demise of the Clovis archeological culture, and a range of other effects. Since gaining widespread attention in 2007, substantial research has focused on testing the 12 main signatures presented as evidence of a catastrophic extraterrestrial event 12,900 years ago. Here we present a review of the impact hypothesis, including its evolution and current variants, and of efforts to test and corroborate the hypothesis. The physical evidence interpreted as signatures of an impact event can be separated into two groups. The first group consists of evidence that has been largely rejected by the scientific community and is no longer in widespread discussion, including: particle tracks in archeological chert; magnetic nodules in Pleistocene bones; impact origin of the Carolina Bays; and elevated concentrations of radioactivity, iridium, and fullerenes enriched in 3He. The second group consists of evidence that has been active in recent research and discussions: carbon spheres and elongates, magnetic grains and magnetic spherules, byproducts of catastrophic wildfire, and nanodiamonds. Over time, however, these signatures have also seen contrary evidence rather than support. Recent studies have shown that carbon spheres and elongates do not represent extraterrestrial carbon nor impact-induced megafires, but are indistinguishable from fungal sclerotia and arthropod fecal material that are a small but common component of many terrestrial deposits. Magnetic grains and spherules are heterogeneously distributed in sediments, but reported measurements of unique peaks in concentrations at the YD onset have yet to be reproduced. The magnetic grains are certainly just iron-rich detrital grains, whereas reported YD magnetic spherules are

  12. A neuroplastic deafferentation hypothesis for bipolar disorder

    PubMed Central

    Rogers, Jonathan; Mirams, Jamie; Patel, Rashmi

    2015-01-01

    Bipolar disorder, characterised by extreme cyclical variations in mood between depression and mania, is a common, debilitating and sometimes fatal psychiatric condition with an unclear aetiology. In this paper we propose a hypothesis for the development of bipolar disorder through which neuroplastic changes in response to an index depressive episode leads to the amplification of subthreshold pleasurable stimuli that then drive conversion into a manic state. This ‘pleasure deafferentation hypothesis’ is reached through a discussion of the neuroscientific basis of deafferentation at the level of the neuron and its role in the development of various neurological and psychiatric phenomena before a case for deafferentation as applied to bipolar disorder is justified and its implications discussed. PMID:26459976

  13. The regulation of the air: a hypothesis

    NASA Astrophysics Data System (ADS)

    Nisbet, E. G.; Fowler, C. M. R.; Nisbet, R. E. R.

    2012-03-01

    We propose the hypothesis that natural selection, acting on the specificity or preference for CO2 over O2 of the enzyme rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase), has controlled the CO2:O2 ratio of the atmosphere since the evolution of photosynthesis and has also sustained the Earth's greenhouse-set surface temperature. Rubisco works in partnership with the nitrogen-fixing enzyme nitrogenase to control atmospheric pressure. Together, these two enzymes control global surface temperature and indirectly the pH and oxygenation of the ocean. Thus, the co-evolution of these two enzymes may have produced clement conditions on the Earth's surface, allowing life to be sustained.

  14. Cerebellar neurocognition and Korsakoff's syndrome: an hypothesis.

    PubMed

    Wijnia, Jan W; Goossensen, Anne

    2010-08-01

    In literature, the cerebellum is given a substantial role in cognitive processes, in addition to traditional views on cerebellar function of regulating motor behaviour. The phenomenon of cerebellar damage causing impairments in memory and executive functioning was observed in various cerebellar disorders. Cerebellar cognitive dysfunction can be interpreted as a disturbance of cerebello-cerebral connections to areas of the cerebral cortex involved in cognitive processing, but the exact nature of the cognitive dysregulation is not known. Memory and executive dysfunction are important clinical features of Korsakoff's syndrome. We hypothesize that the Korsakoff syndrome might be an example of cerebellar neurocognitive dysfunctioning, caused by cerebello-cerebral pathways being disconnected in brain areas that are classically affected in Wernicke's encephalopathy. Further research is needed to support the possibility of cerebellar neurocognitive disturbances in Korsakoff's syndrome. If correct, this hypothesis may contribute to a better understanding of the clinical and neuropsychological profile of Korsakoff's syndrome. PMID:20303220

  15. The Gaia hypothesis: Can it be tested?

    NASA Astrophysics Data System (ADS)

    Kirchner, James W.

    1989-05-01

    The Gaia hypothesis' central theme is that biological processes homeostatically maintain, on a planetary scale, geochemical and climatic conditions favorable for life. A number of distinct hypotheses have been proposed, spanning a range from the self-evident to the highly speculative. The self-evident forms of Gaia reiterate the well-documented fact that biological processes are critical to biogeochemical cycles, adding the straightforward (though important) point that the coupling between biotic and physical processes should create feedback loops. The speculative forms of Gaia assert that biological processes regulate the physical environment, keeping Earth's climate and surface geochemistry stable and favorable for life. As metaphors, these versions of Gaia are intriguing, untestable, and, if taken literally as a basis for research, potentially misleading. As hypotheses, they are ill-defined, unparsimonious, and unfalsifiable.

  16. A Reassessment of the Mars Ocean Hypothesis

    NASA Technical Reports Server (NTRS)

    Parker, T. J.

    2004-01-01

    Initial work on the identification and mapping of potential ancient shorelines on Mars was based on Viking Orbiter image data (Parker et al., 1987, 1989, 1993). The Viking Orbiters were designed to locate landing site for the two landers and were not specifically intended to map the entire planet. Fortunately, they mapped the entire planet. Unfortunately, they did so at an average resolution of greater than 200m/pixel. Higher resolution images, even mosaics of interesting regions, are available, but relatively sparse. Mapping of shorelines on Earth requires both high-resolution aerial photos or satellite images and good topographic information. Three significant sources of additional data from missions subsequent to Viking are useful for reassessing the ocean hypothesis. These are: MGS MOC images; MGS MOLA topography; Odyssey THEMIS IR and VIS images; and MER surface geology at Meridiani and Gusev. Okay, my mistake: Four.

  17. Hypothesis on how to measure electromagnetic hypersensitivity.

    PubMed

    Tuengler, Andreas; von Klitzing, Lebrecht

    2013-09-01

    Electromagnetic hypersensitivity (EHS) is an ill-defined term to describe the fact that people who experience health symptoms in the vicinity of electromagnetic fields (EMFs) regard them as causal for their complaints. Up to now most scientists assume a psychological cause for the suffering of electromagnetic hypersensitive individuals. This paper addresses reasons why most provocation studies could not find any association between EMF exposure and EHS and presents a hypothesis on diagnosis and differentiation of this condition. Simultaneous recordings of heart rate variability, microcirculation and electric skin potentials are used for classification of EHS. Thus, it could be possible to distinguish "genuine" electromagnetic hypersensitive individuals from those who suffer from other conditions. PMID:23301924

  18. A critical examination of the bioplasma hypothesis.

    PubMed

    Quickenden, T I; Tilbury, R N

    1986-01-01

    The hypothesis of Zon (Physiol. Chem. and Physics 11, 501-506 (1979); 12, 357-364 (1980] that regions of semiconduction within living organisms may exhibit plasma behaviour is shown to be most unlikely. Although charge carrier concentrations may be acceptable, calculated Debye lengths are shown to be only marginally acceptable and calculated plasma frequencies are not sufficiently high to ensure that charge carrier motions are governed by electrical and magnetic forces rather than hydrodynamic considerations. For the latter reason, conventional semiconductors do not exhibit plasma behaviour except close to absolute zero and if they are free from impurities and lattice disorder. The experimental evidences presented for the existence of biological plasma (bioplasma) from the areas of Kirlian photography, mitogenetic radiation, acupuncture and studies of biological fields, are largely explainable in conventional terms without invoking the existence of biological plasma. PMID:3809263

  19. On the Geodesic Hypothesis in General Relativity

    NASA Astrophysics Data System (ADS)

    Yang, Shiwu

    2014-02-01

    In this paper, we give a rigorous derivation of Einstein's geodesic hypothesis in general relativity. We use small material bodies governed by the nonlinear Klein-Gordon equations to approximate the test particle. Given a vacuum spacetime , we consider the initial value problem for the Einstein-scalar field system. For all sufficiently small ɛ and δ ≤ ɛ q , q > 1, where δ, ɛ are the amplitude and size of the particle, we show the existence of the solution to the Einstein-scalar field system with the property that the energy of the particle is concentrated along a timelike geodesic. Moreover, the gravitational field produced by is negligibly small in C 1, that is, the spacetime metric g is C 1 close to the given vacuum metric h. These results generalize those obtained by Stuart in (Ann Sci École Norm Sup (4) 37(2):312-362, 2004, J Math Pures Appl (9) 83(5):541-587, 2004).

  20. Sibling dilution hypothesis: a regression surface analysis.

    PubMed

    Marjoribanks, K

    2001-08-01

    This study examined relationships between sibship size (the number of children in a family), birth order, and measures of academic performance, academic self-concept, and educational aspirations at different levels of family educational resources. As part of a national longitudinal study of Australian secondary school students data were collected from 2,530 boys and 2,450 girls in Years 9 and 10. Regression surfaces were constructed from models that included terms to account for linear, interaction, and curvilinear associations among the variables. Analysis suggests the general propositions (a) family educational resources have significant associations with children's school-related outcomes at different levels of sibling variables, the relationships for girls being curvilinear, and (b) sibling variables continue to have small significant associations with affective and cognitive outcomes, after taking into account variations in family educational resources. That is, the investigation provides only partial support for the sibling dilution hypothesis. PMID:11729548

  1. The hexagon hypothesis: Six disruptive scenarios.

    PubMed

    Burtles, Jim

    2015-01-01

    This paper aims to bring a simple but effective and comprehensive approach to the development, delivery and monitoring of business continuity solutions. To ensure that the arguments and principles apply across the board, the paper sticks to basic underlying concepts rather than sophisticated interpretations. First, the paper explores what exactly people are defending themselves against. Secondly, the paper looks at how defences should be set up. Disruptive events tend to unfold in phases, each of which invites a particular style of protection, ranging from risk management through to business continuity to insurance cover. Their impact upon any business operation will fall into one of six basic scenarios. The hexagon hypothesis suggests that everyone should be prepared to deal with each of these six disruptive scenarios and it provides them with a useful benchmark for business continuity. PMID:26420396

  2. Multiple model cardinalized probability hypothesis density filter

    NASA Astrophysics Data System (ADS)

    Georgescu, Ramona; Willett, Peter

    2011-09-01

    The Probability Hypothesis Density (PHD) filter propagates the first-moment approximation to the multi-target Bayesian posterior distribution while the Cardinalized PHD (CPHD) filter propagates both the posterior likelihood of (an unlabeled) target state and the posterior probability mass function of the number of targets. Extensions of the PHD filter to the multiple model (MM) framework have been published and were implemented either with a Sequential Monte Carlo or a Gaussian Mixture approach. In this work, we introduce the multiple model version of the more elaborate CPHD filter. We present the derivation of the prediction and update steps of the MMCPHD particularized for the case of two target motion models and proceed to show that in the case of a single model, the new MMCPHD equations reduce to the original CPHD equations.

  3. Large numbers hypothesis. II - Electromagnetic radiation

    NASA Technical Reports Server (NTRS)

    Adams, P. J.

    1983-01-01

    This paper develops the theory of electromagnetic radiation in the units covariant formalism incorporating Dirac's large numbers hypothesis (LNH). A direct field-to-particle technique is used to obtain the photon propagation equation which explicitly involves the photon replication rate. This replication rate is fixed uniquely by requiring that the form of a free-photon distribution function be preserved, as required by the 2.7 K cosmic radiation. One finds that with this particular photon replication rate the units covariant formalism developed in Paper I actually predicts that the ratio of photon number to proton number in the universe varies as t to the 1/4, precisely in accord with LNH. The cosmological red-shift law is also derived and it is shown to differ considerably from the standard form of (nu)(R) - const.

  4. Bayesian hypothesis testing for key comparisons

    NASA Astrophysics Data System (ADS)

    Wübbeler, Gerd; Bodnar, Olha; Elster, Clemens

    2016-08-01

    Unilateral degrees of equivalence are the key result in the analysis of key comparison data and they are used to approve, or disapprove, calibration and measurement capabilities of the participating laboratories. To this end, it is checked whether a degree of equivalence differs significantly from zero. Proceeding in such a way can be viewed as carrying out a classical hypothesis test. We develop a Bayesian counterpart to this approach which has the advantage that it can include prior assessment of the corresponding Consultative Committee about the calibration and measurement capabilities of the participating laboratories. Simple expressions are derived and their implementation is provided in terms of MATLAB® and R programs. The novel procedure is illustrated by its application to two recent key comparisons CCL-K1 and CCM.FF-K4.1.2011.

  5. Ecological Hypothesis of Dentin and Root Caries.

    PubMed

    Takahashi, Nobuhiro; Nyvad, Bente

    2016-01-01

    Recent advances regarding the caries process indicate that ecological phenomena induced by bacterial acid production tilt the de- and remineralization balance of the dental hard tissues towards demineralization through bacterial acid-induced adaptation and selection within the microbiota - from the dynamic stability stage to the aciduric stage via the acidogenic stage [Takahashi and Nyvad, 2008]. Dentin and root caries can also be partly explained by this hypothesis; however, the fact that these tissues contain a considerable amount of organic material suggests that protein degradation is involved in caries formation. In this review, we compiled relevant histological, biochemical, and microbiological information about dentin/root caries and refined the hypothesis by adding degradation of the organic matrix (the proteolytic stage) to the abovementioned stages. Bacterial acidification not only induces demineralization and exposure of the organic matrix in dentin/root surfaces but also activation of dentin-embedded and salivary matrix metalloproteinases and cathepsins. These phenomena initiate degradation of the demineralized organic matrix in dentin/root surfaces. While a bacterial involvement has never been confirmed in the initial degradation of organic material, the detection of proteolytic/amino acid-degrading bacteria and bacterial metabolites in dentin and root caries suggests a bacterial digestion and metabolism of partly degraded matrix. Moreover, bacterial metabolites might induce pulpitis as an inflammatory/immunomodulatory factor. Root and dentin surfaces are always at risk of becoming demineralized in the oral cavity, and exposed organic materials can be degraded by host-derived proteases contained in saliva and dentin itself. New approaches to the prevention and treatment of root/dentin caries are required. PMID:27458979

  6. Different Dimensions of Spatial Ability.

    ERIC Educational Resources Information Center

    Eliot, John; Hauptman, Anna

    1981-01-01

    Indicates that spatial ability describes a variety of different behaviors and briefly reviews efforts to define intelligence factors and identify processes involved in solving tasks requiring spatial ability. (DS)

  7. Mars' Oceanus Borealis, Ancient Glaciers, and the MEGAOUTFLO Hypothesis

    NASA Technical Reports Server (NTRS)

    Baker, V. R.; Strom, R. G.; Dohm, J. M.; Gulick, V. C.; Kargel, J. S.; Komatsu, G.; Ori, G. G.; Rice, J. W., Jr.

    2000-01-01

    Recent results from Global Surveyor corroborate the hypothesis that episodes of outburst flooding produced ponded water and climate change on Mars. This hypothesis colligates diverse facts concerning the Martian landscape and its history into a unified genetic system.

  8. Understanding Hydrological Trends with Budyko Hypothesis

    NASA Astrophysics Data System (ADS)

    Cong, Z.; Yang, D.

    2010-12-01

    In order to predict future hydrological trends, it is important to understand those that have occurred in the past. In this study, we summarized the hydrological trends in China based on observations and water balance, including precipitation, pan evaporation and actual evaporation, and then understood these trends with complementary relation curves and Budyko hypothesis. The entire area of China was divided into 10 basins and 317 weather stations with data from 1956 to 2005 were selected for trend analysis. We found that (1) precipitation has decreased in the north but has increased in the south due to weakening monsoon winds over the past 50 years; (2) pan evaporation decreased before 1980s, which was caused by the decreasing in radiation and wind speed, but increased after 1980s, which was caused by the decreasing in vapor pressure deficit due to strong warming; (3) actual evaporation estimated by the water balance equation showed a decreasing trend in both the north and the south. With the stepwise regression method, we concluded that precipitation had a greater impact on pan evaporation in the north while sun duration had a more significant impact on hydrological processes in the south. Using complementary relation curves, we concluded that the decrease of actual evaporation in the north was caused by the decrease in precipitation while the decrease of actual evaporation in the south was caused by the decrease in potential evaporation. With the differentiation to time of the Fu’s equation expressing the Budyko hypothesis, we got the relation: ∂E/∂t=α(∂P/∂t)+β(∂E0/∂t). For the north basins, the α is about 0.7 to 0.8 and the β is about 0.1, which means that the actual evaporation is more sensitive to the precipitation, so the actual evaporation trend is mainly controlled by the precipitation trend. For the south basins, the α is smaller and the β is greater, which means that the actual evaporation is more sensitive to the potential

  9. Hypothesis of demodicidosis rosacea flushing etiopathogenesis.

    PubMed

    Robledo, Mary Ann; Orduz, Mariana

    2015-04-01

    Most of the patients with erythematotelangiectatic rosacea are characterized by flushing, oedema and telangiectasia. The etiopathogenesis of the flushing in rosacea patients is unknown. Clinically the flushing in rosacea is similar to the "Asian flushing syndrome". Most Asians have an overactive alcohol dehydrogenase (ADH) that tends to break down alcohol into acetaldehyde faster. People with "Asians flushing syndrome" have a genetic disorder with the Aldehyde Dehydrogenase 2(∗)2 (ALDH2(∗)2) allele. This is the reason why they do not metabolize very well the acetaldehyde that comes from the alcohol, which means that acetaldehyde takes much longer to clear from their blood. ALDH2 enzyme is primarily responsible for oxidation of acetaldehyde derived from ethanol metabolism, as well as oxidation of various other endogenous and exogenous aldehydes. Acetaldehyde produces the vasodilatation in the "Asian flushing syndrome". The antibodies against the GroEl chaperonin protein, a 62-kDa heat shock protein were found in the Bacillus oleronius isolated from Demodex mites, in rosacea patients. The GroEl chaperonin protein is a protein that plays a key role in normal folding of ALDH2. If the GroEl chaperonin antibodies found in patients with rosacea, cross react with the human GroEl chaperonin protein, they will not fold normally the ALDH2, and then the enzyme will not metabolize the acetaldehyde. Many of the patients with rosacea have a concomitant infection with Helicobacter pylori in their stomach. The H.pylori produces high amounts of acetaldehyde, which comes from their metabolism of ethanol or carbohydrates. As a result, high amounts of acetaldehyde will circulate for longer time in the blood, until the liver CYP2E1(p450) enzyme system finally metabilizes the acetaldehyde, during that period of time the patients will experience a flushing as well as the people with the "Asian flushing syndrome" suffer when they drink ethanol. To prove the hypothesis it is necessary

  10. Cortical activity patterns predict speech discrimination ability

    PubMed Central

    Engineer, Crystal T; Perez, Claudia A; Chen, YeTing H; Carraway, Ryan S; Reed, Amanda C; Shetake, Jai A; Jakkamsetti, Vikram; Chang, Kevin Q; Kilgard, Michael P

    2010-01-01

    Neural activity in the cerebral cortex can explain many aspects of sensory perception. Extensive psychophysical and neurophysiological studies of visual motion and vibrotactile processing show that the firing rate of cortical neurons averaged across 50–500 ms is well correlated with discrimination ability. In this study, we tested the hypothesis that primary auditory cortex (A1) neurons use temporal precision on the order of 1–10 ms to represent speech sounds shifted into the rat hearing range. Neural discrimination was highly correlated with behavioral performance on 11 consonant-discrimination tasks when spike timing was preserved and was not correlated when spike timing was eliminated. This result suggests that spike timing contributes to the auditory cortex representation of consonant sounds. PMID:18425123

  11. Does Environmental Heterogeneity Promote Cognitive Abilities?

    PubMed

    González-Gómez, Paulina L; Razeto-Barry, Pablo; Araya-Salas, Marcelo; Estades, Cristian F

    2015-09-01

    In the context of global change the possible loss of biodiversity has been identified as a major concern. Biodiversity could be seriously threatened as a direct consequence of changes in availability of food, changing thermal conditions, and loss and fragmentation of habitat. Considering the magnitude of global change, an understanding of the mechanisms involved in coping with a changing environment is urgent. We explore the hypothesis that species and individuals experiencing highly variable environments are more likely to develop a wider range of responses to handle the different and unpredictable conditions imposed by global change. In the case of vertebrates, the responses to the challenges imposed by unpredictable perturbations ultimately are linked to cognitive abilities allowing the solving of problems, and the maximization of energy intake. Our models were hummingbirds, which offer a particularly compelling group in which to examine the functional and mechanistic links between behavioral and energetic strategies in individuals experiencing different degrees of social and environmental heterogeneity. PMID:26082484

  12. In Defense of the Play-Creativity Hypothesis

    ERIC Educational Resources Information Center

    Silverman, Irwin W.

    2016-01-01

    The hypothesis that pretend play facilitates the creative thought process in children has received a great deal of attention. In a literature review, Lillard et al. (2013, p. 8) concluded that the evidence for this hypothesis was "not convincing." This article focuses on experimental and training studies that have tested this hypothesis.…

  13. Testing the Hamilton-Zuk hypothesis: past, present, and future.

    PubMed

    Balenger, Susan L; Zuk, Marlene

    2014-10-01

    Hamilton and Zuk proposed a good-genes model of sexual selection in which genetic variation can be maintained when females prefer ornaments that indicate resistance to parasites. When trait expression depends on a male's resistance, the co-adaptive cycles between host resistance and parasite virulence provide a mechanism in which genetic variation for fitness is continually renewed. The model made predictions at both the intraspecific and interspecific levels. In the three decades since its publication, these predictions have been theoretically examined in models of varying complexity, and empirically tested across many vertebrate and invertebrate taxa. Despite such prolonged interest, however, it has turned out to be extremely difficult to empirically demonstrate the process described, in part because we have not been able to test the underlying mechanisms that would unequivocally identify how parasites act as mediators of sexual selection. Here, we discuss how the use of high-throughput sequencing datasets available from modern genomic approaches might improve our ability to test this model. We expect that important contributions will come through the ability to identify and quantify the suite of parasites likely to influence the evolution of hosts' resistance, to confidently reconstruct phylogenies of both host and parasite taxa, and, perhaps most exciting, to detect generational cycles of heritable variants in populations of hosts and parasites. Integrative approaches, building on systems undergoing parasite-mediated selection with genomic resources already available, will be particularly useful in moving toward robust tests of this hypothesis. We finish by presenting case studies of well-studied host-parasite relationships that represent promising avenues for future research. PMID:24876194

  14. A Matched Filter Hypothesis for Cognitive Control

    PubMed Central

    Thompson-Schill, Sharon L.

    2013-01-01

    The prefrontal cortex exerts top-down influences on several aspects of higher-order cognition by functioning as a filtering mechanism that biases bottom-up sensory information toward a response that is optimal in context. However, research also indicates that not all aspects of complex cognition benefit from prefrontal regulation. Here we review and synthesize this research with an emphasis on the domains of learning and creative cognition, and outline how the appropriate level of cognitive control in a given situation can vary depending on the organism's goals and the characteristics of the given task. We offer a Matched Filter Hypothesis for cognitive control, which proposes that the optimal level of cognitive control is task-dependent, with high levels of cognitive control best suited to tasks that are explicit, rule-based, verbal or abstract, and can be accomplished given the capacity limits of working memory and with low levels of cognitive control best suited to tasks that are implicit, reward-based, non-verbal or intuitive, and which can be accomplished irrespective of working memory limitations. Our approach promotes a view of cognitive control as a tool adapted to a subset of common challenges, rather than an all-purpose optimization system suited to every problem the organism might encounter. PMID:24200920

  15. The cometary breakup hypothesis re-examined

    NASA Astrophysics Data System (ADS)

    La Violette, P. A.

    1987-02-01

    The theory that a Chiron-like progenitor of both Comet Encke and the Tunguska cosmic body may have fragmented beginning around 22,000 years BP and that debris from this breakup was responsible for producing the high heavy metal concentrations observed in the Late Wisconin stage polar ice is shown to be incorrectly founded. This paper reexamines the geochemical comparison which Clube and Napier (1984) make between the composition of the Tunguska cosmic body and elemental abundances previously reported for a sample of Sn-rich dust retrieved from the Wisconsin section of the Camp Century ice core. No evidence is found that would link these two sources to a common origin. Thus the hypothesis that a cometary breakup was responsible for modulating the earth's climate and perpetuating the last ice age is unfounded. On the other hand, evidence is presented indicating that debris from the Tunguska explosion may be present in a firm layer at Dome C, East Antarctica. Analysis of the geochemical data for this stratum leads to an estimate of 10 to the 6th to 10 to the 7th t for the mass of the Tunguska body, in approximate agreement with previous determinations.

  16. The social brain hypothesis of schizophrenia.

    PubMed

    Burns, Jonathan

    2006-06-01

    The social brain hypothesis is a useful heuristic for understanding schizophrenia. It focuses attention on the core Bleulerian concept of autistic alienation and is consistent with well-replicated findings of social brain dysfunction in schizophrenia as well as contemporary theories of human cognitive and brain evolution. The contributions of Heidegger, Merleau-Ponty and Wittgenstein allow us to arrive at a new "philosophy of interpersonal relatedness", which better reflects the "embodied mind" and signifies the end of Cartesian dualistic thinking. In this paper I review the evolution, development and neurobiology of the social brain - the anatomical and functional substrate for adaptive social behaviour and cognition. Functional imaging identifies fronto-temporal and fronto-parietal cortical networks as comprising the social brain, while the discovery of "mirror neurons" provides an understanding of social cognition at a cellular level. Patients with schizophrenia display abnormalities in a wide range of social cognition tasks such as emotion recognition, theory of mind and affective responsiveness. Furthermore, recent research indicates that schizophrenia is a disorder of functional and structural connectivity of social brain networks. These findings lend support to the claim that schizophrenia represents a costly by-product of social brain evolution in Homo sapiens. Individuals with this disorder find themselves seriously disadvantaged in the social arena and vulnerable to the stresses of their complex social environments. This state of "disembodiment" and interpersonal alienation is the core phenomenon of schizophrenia and the root cause of intolerable suffering in the lives of those affected. PMID:16946939

  17. Hypothesis exploration with visualization of variance

    PubMed Central

    2014-01-01

    Background The Consortium for Neuropsychiatric Phenomics (CNP) at UCLA was an investigation into the biological bases of traits such as memory and response inhibition phenotypes—to explore whether they are linked to syndromes including ADHD, Bipolar disorder, and Schizophrenia. An aim of the consortium was in moving from traditional categorical approaches for psychiatric syndromes towards more quantitative approaches based on large-scale analysis of the space of human variation. It represented an application of phenomics—wide-scale, systematic study of phenotypes—to neuropsychiatry research. Results This paper reports on a system for exploration of hypotheses in data obtained from the LA2K, LA3C, and LA5C studies in CNP. ViVA is a system for exploratory data analysis using novel mathematical models and methods for visualization of variance. An example of these methods is called VISOVA, a combination of visualization and analysis of variance, with the flavor of exploration associated with ANOVA in biomedical hypothesis generation. It permits visual identification of phenotype profiles—patterns of values across phenotypes—that characterize groups. Visualization enables screening and refinement of hypotheses about variance structure of sets of phenotypes. Conclusions The ViVA system was designed for exploration of neuropsychiatric hypotheses by interdisciplinary teams. Automated visualization in ViVA supports ‘natural selection’ on a pool of hypotheses, and permits deeper understanding of the statistical architecture of the data. Large-scale perspective of this kind could lead to better neuropsychiatric diagnostics. PMID:25097666

  18. Minireview: Organizational Hypothesis: Instances of the Fingerpost

    PubMed Central

    Breedlove, S. Marc

    2010-01-01

    There is now compelling evidence that the ratio of the length of the second digit divided by the length of the fourth digit (2D:4D) is affected by prenatal androgens in humans. This ratio is greater in females than males from fetal life through adulthood, correlates with polymorphism in the androgen receptor gene in men, is feminine in XY androgen insensitivity syndrome, and masculinized in congenital adrenal hyperplasia. Using 2D:4D as a correlate, researchers have found evidence that prenatal androgens affect many sexually differentiated human behaviors, including sexual orientation in women (but not in men), attention deficit disorder, autism, eating disorders, aggression, and risk-taking. In each case, lower 2D:4D, indicative of greater prenatal androgen stimulation, is associated with behavior more commonly displayed by males than females. The correlation between 2D:4D and prenatal androgen stimulation is too imperfect to accurately predict the phenotype of a particular individual, even in terms of sex. However, digit ratio is the best available retrospective marker of average differences in prenatal androgen stimulation between groups of people, and/or correlations of prenatal androgen stimulation with particular behaviors and characteristics within a group. Thus digit ratios offer a valid test of the organizational hypothesis that androgens act early in life to masculinize various human behaviors. PMID:20631003

  19. Handedness in man: The energy availability hypothesis.

    PubMed

    Chan, Yoo Kuen; Loh, Pui San

    2016-09-01

    More than 90% of the human species are right handed. Although outwardly our body appears symmetrical, a 50/50% lateralization in handedness never occurs. Neither have we seen more than 50% left handedness in any subset of the human population. By 12-15weeks of intrauterine life, as many as 6 times more fetuses are noted by ultrasound studies to be sucking on their right thumbs. Distinct difference in oxygenation leading to dissimilar energy availability between right and left subclavian arteries in place by week 9 of life may hold the clue to the lateralization of hand function and eventually, the same in the brain. We know there is a higher incidence of left handedness in males, twins, premature babies and those born to mothers who smoke. They may represent a subset with less distinct difference in oxygenation between the 2 subclavian arteries during the fetal stage. This hypothesis if correct not only closes the gap in understanding human handedness and lateralization but also opens a vista for new research to focus on in utero tissue energy availability and its impact on outcome in life. PMID:27515214

  20. Minireview: Organizational hypothesis: instances of the fingerpost.

    PubMed

    Breedlove, S Marc

    2010-09-01

    There is now compelling evidence that the ratio of the length of the second digit divided by the length of the fourth digit (2D:4D) is affected by prenatal androgens in humans. This ratio is greater in females than males from fetal life through adulthood, correlates with polymorphism in the androgen receptor gene in men, is feminine in XY androgen insensitivity syndrome, and masculinized in congenital adrenal hyperplasia. Using 2D:4D as a correlate, researchers have found evidence that prenatal androgens affect many sexually differentiated human behaviors, including sexual orientation in women (but not in men), attention deficit disorder, autism, eating disorders, aggression, and risk-taking. In each case, lower 2D:4D, indicative of greater prenatal androgen stimulation, is associated with behavior more commonly displayed by males than females. The correlation between 2D:4D and prenatal androgen stimulation is too imperfect to accurately predict the phenotype of a particular individual, even in terms of sex. However, digit ratio is the best available retrospective marker of average differences in prenatal androgen stimulation between groups of people, and/or correlations of prenatal androgen stimulation with particular behaviors and characteristics within a group. Thus digit ratios offer a valid test of the organizational hypothesis that androgens act early in life to masculinize various human behaviors. PMID:20631003

  1. The differential adhesion hypothesis: a direct evaluation.

    PubMed

    Foty, Ramsey A; Steinberg, Malcolm S

    2005-02-01

    The differential adhesion hypothesis (DAH), advanced in the 1960s, proposed that the liquid-like tissue-spreading and cell segregation phenomena of development arise from tissue surface tensions that in turn arise from differences in intercellular adhesiveness. Our earlier measurements of liquid-like cell aggregate surface tensions have shown that, without exception, a cell aggregate of lower surface tension tends to envelop one of higher surface tension to which it adheres. We here measure the surface tensions of L cell aggregates transfected to express N-, P- or E-cadherin in varied, measured amounts. We report that in these aggregates, in which cadherins are essentially the only cell-cell adhesion molecules, the aggregate surface tensions are a direct, linear function of cadherin expression level. Taken together with our earlier results, the conclusion follows that the liquid-like morphogenetic cell and tissue rearrangements of cell sorting, tissue spreading and segregation represent self-assembly processes guided by the diminution of adhesive-free energy as cells tend to maximize their mutual binding. This conclusion relates to the physics governing these morphogenetic phenomena and applies independently of issues such as the specificities of intercellular adhesives. PMID:15649477

  2. What drives masting? The phenological synchrony hypothesis.

    PubMed

    Koenig, Walter D; Knops, Johannes M H; Carmen, William J; Pearse, Ian S

    2015-01-01

    Annually variable and synchronous seed production, or masting behavior, is a widespread phenomenon with dramatic effects on wildlife populations and their associated communities. Proximally, masting is often correlated with environmental factors and most likely involves differential pollination success and resource allocation, but little is known about how these factors interact or how they influence seed production. We studied masting in the valley oak (Quercus lobata Née), a California endemic tree, and report evidence that phenological synchrony in flowering driven by microclimatic variability determines the size of the acorn crop through its effects on pollen availability and fertilization success. These findings integrate two of the major factors believed to influence seed production in wind-pollinated species-environmental conditions and pollen limitation-by means of a coherent mechanistic hypothesis for how highly variable and synchronized annual seed production is accomplished. We illustrate how, by means of a simulation based on the mechanism proposed here, climate change may influence masting patterns through its effects on environmental variability. PMID:26236903

  3. Homocysteine, Iron and Cardiovascular Disease: A Hypothesis

    PubMed Central

    Baggott, Joseph E.; Tamura, Tsunenobu

    2015-01-01

    Elevated circulating total homocysteine (tHcy) concentrations (hyperhomocysteinemia) have been regarded as an independent risk factor for cardiovascular disease (CVD). However, several large clinical trials to correct hyperhomocysteinemia using B-vitamin supplements (particularly folic acid) have largely failed to reduce the risk of CVD. There is no doubt that a large segment of patients with CVD have hyperhomocysteinemia; therefore, it is reasonable to postulate that circulating tHcy concentrations are in part a surrogate marker for another, yet-to-be-identified risk factor(s) for CVD. We found that iron catalyzes the formation of Hcy from methionine, S-adenosylhomocysteine and cystathionine. Based on these findings, we propose that an elevated amount of non-protein-bound iron (free Fe) increases circulating tHcy. Free Fe catalyzes the formation of oxygen free radicals, and oxidized low-density lipoprotein is a well-established risk factor for vascular damage. In this review, we discuss our findings on iron-catalyzed formation of Hcy from thioethers as well as recent findings by other investigators on this issue. Collectively, these support our hypothesis that circulating tHcy is in part a surrogate marker for free Fe, which is one of the independent risk factors for CVD. PMID:25668155

  4. Hypothesis test for synchronization: Twin surrogates revisited

    NASA Astrophysics Data System (ADS)

    Romano, M. Carmen; Thiel, Marco; Kurths, Jürgen; Mergenthaler, Konstantin; Engbert, Ralf

    2009-03-01

    The method of twin surrogates has been introduced to test for phase synchronization of complex systems in the case of passive experiments. In this paper we derive new analytical expressions for the number of twins depending on the size of the neighborhood, as well as on the length of the trajectory. This allows us to determine the optimal parameters for the generation of twin surrogates. Furthermore, we determine the quality of the twin surrogates with respect to several linear and nonlinear statistics depending on the parameters of the method. In the second part of the paper we perform a hypothesis test for phase synchronization in the case of experimental data from fixational eye movements. These miniature eye movements have been shown to play a central role in neural information processing underlying the perception of static visual scenes. The high number of data sets (21 subjects and 30 trials per person) allows us to compare the generated twin surrogates with the "natural" surrogates that correspond to the different trials. We show that the generated twin surrogates reproduce very well all linear and nonlinear characteristics of the underlying experimental system. The synchronization analysis of fixational eye movements by means of twin surrogates reveals that the synchronization between the left and right eye is significant, indicating that either the centers in the brain stem generating fixational eye movements are closely linked, or, alternatively that there is only one center controlling both eyes.

  5. Impulse Control Disorders - The Continuum Hypothesis.

    PubMed

    Stenberg, Georg

    2016-01-01

    The group Parkinson Inside Out is composed of health professionals and academic researchers who have been diagnosed with Parkinson's Disease. In our discussions we try to make use of both our inside perspective as patients, and our outside perspective as professionals. In this paper, we apply the two perspectives to the Impulse Control Disorders. These impulsive behaviour patterns are thought to be relatively uncommon side effects of some of the medication used in dopamine replacement therapy. The phenomenon is usually described as relatively rare (<15%), and mainly confined to patients with special vulnerabilities. In contrast, we propose that having some problems with controlling impulses is a very common experience for patients undergoing dopamine replacement therapy. They result from difficulties in decision making engendered by variations in dopamine accessibility in the reward centre of the brain. Only in a minority do the consequences grow to the damaging proportions of a disorder, but most patients are probably affected to some degree. Seeing, and measuring, decision difficulties as a continuous dimension, rather than as a discrete category, brings increased possibilities for early detection and continuous monitoring. With reliable measures of the propensity for impulsive decision making, it may become possible to both reap the benefits and avoid the dangers of the dopamine agonists. We point to ways of empirically testing our continuity hypothesis. PMID:27031861

  6. The social brain hypothesis of schizophrenia

    PubMed Central

    BURNS, JONATHAN

    2006-01-01

    The social brain hypothesis is a useful heuristic for understanding schizophrenia. It focuses attention on the core Bleulerian concept of autistic alienation and is consistent with well-replicated findings of social brain dysfunction in schizophrenia as well as contemporary theories of human cognitive and brain evolution. The contributions of Heidegger, Merleau-Ponty and Wittgenstein allow us to arrive at a new "philosophy of interpersonal relatedness", which better reflects the "embodied mind" and signifies the end of Cartesian dualistic thinking. In this paper I review the evolution, development and neurobiology of the social brain - the anatomical and functional substrate for adaptive social behaviour and cognition. Functional imaging identifies fronto-temporal and fronto-parietal cortical networks as comprising the social brain, while the discovery of "mirror neurons" provides an understanding of social cognition at a cellular level. Patients with schizophrenia display abnormalities in a wide range of social cognition tasks such as emotion recognition, theory of mind and affective responsiveness. Furthermore, recent research indicates that schizophrenia is a disorder of functional and structural connectivity of social brain networks. These findings lend support to the claim that schizophrenia represents a costly by-product of social brain evolution in Homo sapiens. Individuals with this disorder find themselves seriously disadvantaged in the social arena and vulnerable to the stresses of their complex social environments. This state of "disembodiment" and interpersonal alienation is the core phenomenon of schizophrenia and the root cause of intolerable suffering in the lives of those affected. PMID:16946939

  7. DAMPs, ageing, and cancer: The 'DAMP Hypothesis'.

    PubMed

    Huang, Jin; Xie, Yangchun; Sun, Xiaofang; Zeh, Herbert J; Kang, Rui; Lotze, Michael T; Tang, Daolin

    2015-11-01

    Ageing is a complex and multifactorial process characterized by the accumulation of many forms of damage at the molecular, cellular, and tissue level with advancing age. Ageing increases the risk of the onset of chronic inflammation-associated diseases such as cancer, diabetes, stroke, and neurodegenerative disease. In particular, ageing and cancer share some common origins and hallmarks such as genomic instability, epigenetic alteration, aberrant telomeres, inflammation and immune injury, reprogrammed metabolism, and degradation system impairment (including within the ubiquitin-proteasome system and the autophagic machinery). Recent advances indicate that damage-associated molecular pattern molecules (DAMPs) such as high mobility group box 1, histones, S100, and heat shock proteins play location-dependent roles inside and outside the cell. These provide interaction platforms at molecular levels linked to common hallmarks of ageing and cancer. They can act as inducers, sensors, and mediators of stress through individual plasma membrane receptors, intracellular recognition receptors (e.g., advanced glycosylation end product-specific receptors, AIM2-like receptors, RIG-I-like receptors, and NOD1-like receptors, and toll-like receptors), or following endocytic uptake. Thus, the DAMP Hypothesis is novel and complements other theories that explain the features of ageing. DAMPs represent ideal biomarkers of ageing and provide an attractive target for interventions in ageing and age-associated diseases. PMID:25446804

  8. Identity of Particles and Continuum Hypothesis

    NASA Astrophysics Data System (ADS)

    Berezin, Alexander A.

    2001-04-01

    Why all electrons are the same? Unlike other objects, particles and atoms (same isotopes) are forbidden to have individuality or personal history (or reveal their hidden variables, even if they do have them). Or at least, what we commonly call physics so far was unable to disprove particle's sameness (Berezin and Nakhmanson, Physics Essays, 1990). Consider two opposing hypotheses: (A) particles are indeed absolutely same, or (B) they do have individuality, but it is beyond our capacity to demonstrate. This dilemma sounds akin to undecidability of Continuum Hypothesis of existence (or not) of intermediate cardinalities between integers and reals (P.Cohen). Both yes and no of it are true. Thus, (alleged) sameness of electrons and atoms may be a physical translation (embodiment) of this fundamental Goedelian undecidability. Experiments unlikely to help: even if we find that all electrons are same within 30 decimal digits, could their masses (or charges) still differ in100-th digit? Within (B) personalized informationally rich (infinitely rich?) digital tails (starting at, say, 100-th decimal) may carry individual record of each particle history. Within (A) parameters (m, q) are indeed exactly same in all digits and their sameness is based on some inherent (meta)physical principle akin to Platonism or Eddington-type numerology.

  9. A matched filter hypothesis for cognitive control.

    PubMed

    Chrysikou, Evangelia G; Weber, Matthew J; Thompson-Schill, Sharon L

    2014-09-01

    The prefrontal cortex exerts top-down influences on several aspects of higher-order cognition by functioning as a filtering mechanism that biases bottom-up sensory information toward a response that is optimal in context. However, research also indicates that not all aspects of complex cognition benefit from prefrontal regulation. Here we review and synthesize this research with an emphasis on the domains of learning and creative cognition, and outline how the appropriate level of cognitive control in a given situation can vary depending on the organism's goals and the characteristics of the given task. We offer a matched filter hypothesis for cognitive control, which proposes that the optimal level of cognitive control is task-dependent, with high levels of cognitive control best suited to tasks that are explicit, rule-based, verbal or abstract, and can be accomplished given the capacity limits of working memory and with low levels of cognitive control best suited to tasks that are implicit, reward-based, non-verbal or intuitive, and which can be accomplished irrespective of working memory limitations. Our approach promotes a view of cognitive control as a tool adapted to a subset of common challenges, rather than an all-purpose optimization system suited to every problem the organism might encounter. PMID:24200920

  10. Codon catalog usage and the genome hypothesis.

    PubMed Central

    Grantham, R; Gautier, C; Gouy, M; Mercier, R; Pavé, A

    1980-01-01

    Frequencies for each of the 61 amino acid codons have been determined in every published mRNA sequence of 50 or more codons. The frequencies are shown for each kind of genome and for each individual gene. A surprising consistency of choices exists among genes of the same or similar genomes. Thus each genome, or kind of genome, appears to possess a "system" for choosing between codons. Frameshift genes, however, have widely different choice strategies from normal genes. Our work indicates that the main factors distinguishing between mRNA sequences relate to choices among degenerate bases. These systematic third base choices can therefore be used to establish a new kind of genetic distance, which reflects differences in coding strategy. The choice patterns we find seem compatible with the idea that the genome and not the individual gene is the unit of selection. Each gene in a genome tends to conform to its species' usage of the codon catalog; this is our genome hypothesis. PMID:6986610

  11. Spectral analysis and the Riemann hypothesis

    NASA Astrophysics Data System (ADS)

    Lachaud, Gilles

    2003-11-01

    The explicit formulas of Riemann and Guinand-Weil relate the set of prime numbers with the set of nontrivial zeros of the zeta function of Riemann. We recall Alain Connes' spectral interpretation of the critical zeros of the Riemann zeta function as eigenvalues of the absorption spectrum of an unbounded operator in a suitable Hilbert space. We then give a spectral interpretation of the zeros of the Dedekind zeta function of an algebraic number field K of degree n in an automorphic setting. If K is a complex quadratic field, the torical forms are the functions defined on the modular surface X, such that the sum of this function over the "Gauss set" of K is zero, and Eisenstein series provide such torical forms. In the case of a general number field, one can associate to K a maximal torus T of the general linear group G. The torical forms are the functions defined on the modular variety X associated to G, such that the integral over the subvariety induced by T is zero. Alternately, the torical forms are the functions which are orthogonal to orbital series on X. We show here that the Riemann hypothesis is equivalent to certain conditions bearing on spaces of torical forms, constructed from Eisenstein series, the torical wave packets. Furthermore, we define a Hilbert space and a self-adjoint operator on this space, whose spectrum equals the set of critical zeros of the Dedekind zeta function of K.

  12. The HU Aqr planetary system hypothesis revisited

    NASA Astrophysics Data System (ADS)

    Goździewski, K.; Słowikowska, A.; Dimitrov, D.; Krzeszowski, K.; Żejmo, M.; Kanbach, G.; Burwitz, V.; Rau, A.; Irawati, P.; Richichi, A.; Gawroński, M.; Nowak, G.; Nasiroglu, I.; Kubicki, D.

    2015-04-01

    We study the mid-egress eclipse timing data gathered for the cataclysmic binary HU Aquarii during the years 1993-2014. The (O-C) residuals were previously attributed to a single ˜7 Jupiter mass companion in ˜5 au orbit or to a stable two-planet system with an unconstrained outermost orbit. We present 22 new observations gathered between 2011 June and 2014 July with four instruments around the world. They reveal a systematic deviation of ˜60-120 s from the older ephemeris. We re-analyse the whole set of the timing data available. Our results provide an erratum to the previous HU Aqr planetary models, indicating that the hypothesis for a third and fourth body in this system is uncertain. The dynamical stability criterion and a particular geometry of orbits rule out coplanar two-planet configurations. A putative HU Aqr planetary system may be more complex, e.g. highly non-coplanar. Indeed, we found examples of three-planet configurations with the middle planet in a retrograde orbit, which are stable for at least 1 Gyr, and consistent with the observations. The (O-C) may be also driven by oscillations of the gravitational quadrupole moment of the secondary, as predicted by the Lanza et al. modification of the Applegate mechanism. Further systematic, long-term monitoring of HU Aqr is required to interpret the (O-C) residuals.

  13. Embryogenesis of bladder exstrophy: A new hypothesis

    PubMed Central

    Kulkarni, Bharati; Chaudhari, Navin

    2008-01-01

    Aims and Objective: To postulate a hypothesis to explain the embryogenesis of exstrophy bladder based on our clinical observations. Materials and Methods: In 27 cases of exstrophy, we measured the distance between the lowermost inguinal skin crease to the root of the penis (clitoris) (B) and the distance between the penis (clitoris) and the scrotum (labia majora) (C). These were compared with age, height and XP distance (distance between xiphisternum and symphysis pubis) matched control group of normal children. The distance between the lowermost inguinal skin crease and the penis (clitoris) (A) was measured in control group. Results: The observation was A = B + C. This implies that in exstrophy bladder, the position of the penis (clitoris) has moved cephalad from the lower border of A to the junction of B and C. Conclusion: Based on the observations, we postulate that abnormal origin of genital tubercle may be the cause of exstrophy bladder. The abnormal origin of primordia of the genital tubercle in more cephalad direction than normal causes wedge effect, which will interfere with the medial migration of the mesoderm as well as the midline approximation of mesodermal structures in the lower abdominal wall, thereby resulting in the exstrophy of bladder. PMID:20011468

  14. Crohn's disease: the cold chain hypothesis.

    PubMed

    Hugot, Jean-Pierre; Alberti, Corinne; Berrebi, Dominique; Bingen, Edouard; Cézard, Jean-Pierre

    2003-12-13

    Crohn's disease is the result of an abnormal immune response of the gut mucosa triggered by one or more environmental risk factors in people with predisposing gene variations, including CARD15 mutations. Epidemiological data allow assessment of familial environmental risk factors related to western lifestyle, diet, bacteria, and domestic hygiene. All findings point to refrigeration as a potential risk factor for Crohn's disease. Furthermore, cold-chain development paralleled the outbreak of Crohn's disease during the 20th century. The cold chain hypothesis suggests that psychrotrophic bacteria such as Yersinia spp and Listeria spp contribute to the disease. These bacteria have been identified in Crohn's disease lesions and we discuss their pathogenic properties with respect to our knowledge of the disease. From a molecular perspective, we postulate that the disease is a result of a defect in host recognition by pathogenic bacterial components that usually escape the immune response (eg, Yop molecules), which results in an excessive host response to these bacteria. PMID:14683664

  15. On the Primary Factors Affecting Linguistic Ability in Pre-School Children.

    ERIC Educational Resources Information Center

    Alahuhta, Eila

    This study tested the hypothesis that children with weaker speech ability have greater difficulties in perception, powers of reasoning and spatial orientation than children with better speech ability, and assessed the value of Apgar scores as a predictive measure of later linguistic disorders. Subjects were 100 children born in 1970 who attended…

  16. Differentiation of Cognitive Abilities as a Function of Neuroticism Level: A Measurement Equivalence/Invariance Analysis

    ERIC Educational Resources Information Center

    Bonaccio, Silvia; Reeve, Charlie L.

    2006-01-01

    This paper investigates the differentiation of cognitive abilities as a function of neuroticism. Specifically, we examine Eysenck and White's [Eysenck, H. J., and White, P. O. (1964). Personality and the measurement of intelligence. British Journal of Educational Psychology, 24, 197-201.] hypothesis that cognitive abilities are less differentiated…

  17. Linking Brain Growth with the Development of Scientific Reasoning Ability and Conceptual Change during Adolescence.

    ERIC Educational Resources Information Center

    Kwon, Yong-Ju; Lawson, Anton E.

    2000-01-01

    Tests the hypothesis that an early adolescent brain growth plateau and spurt exists, and that this plateau and spurt influence students' ability to reason scientifically and to learn theoretical science concepts. Finds that measures of students' (n=210) prefrontal lobe activity correlated highly with scientific reasoning ability, and that these…

  18. Aptitude Test Score Validity: No Moderating Effect Due to Job Ability Requirement Differences.

    ERIC Educational Resources Information Center

    Jones, Gwen E.; Ree, Malcolm James

    1998-01-01

    This study tested the specificity-generality hypothesis regarding moderation of aptitude test validity by job ability requirement differences using 24,482 Air Force enlistees in 37 jobs. Moderating effects due to job differences were not found, and job ability differences did not moderate the relationship between the amount of "g" measured by a…

  19. Who Benefits from Learning with 3D Models?: The Case of Spatial Ability

    ERIC Educational Resources Information Center

    Huk, T.

    2006-01-01

    Empirical studies that focus on the impact of three-dimensional (3D) visualizations on learning are to date rare and inconsistent. According to the ability-as-enhancer hypothesis, high spatial ability learners should benefit particularly as they have enough cognitive capacity left for mental model construction. In contrast, the…

  20. Fungiculture or Termite Husbandry? The Ruminant Hypothesis.

    PubMed

    Nobre, Tânia; Aanen, Duur K

    2012-01-01

    We present a new perspective for the role of Termitomyces fungi in the mutualism with fungus-growing termites. According to the predominant view, this mutualism is as an example of agriculture with termites as farmers of a domesticated fungus crop, which is used for degradation of plant-material and production of fungal biomass. However, a detailed study of the literature indicates that the termites might as well be envisioned as domesticates of the fungus. According to the "ruminant hypothesis" proposed here, termite workers, by consuming asexual fruiting bodies not only harvest asexual spores, but also lignocellulolytic enzymes, which they mix with foraged plant material and enzymes of termite and possibly bacterial origin. This mixture is the building material of the fungus garden and facilitates efficient degradation of plant material. The fungus garden thus functions as an external rumen for termites and primarily the fungi themselves benefit from their own, and gut-derived, lignocellulolytic enzymes, using the termites to efficiently mix these with their growth substrate. Only secondarily the termites benefit, when they consume the degraded, nitrogen-enriched plant-fungus mixture a second time. We propose that the details of substrate use, and the degree of complementarity and redundancy among enzymes in food processing, determine selection of horizontally transmitted fungal symbionts at the start of a colony: by testing spores on a specific, mechanically and enzymatically pre-treated growth substrate, the termite host has the opportunity to select specific fungal symbionts. Potentially, the gut-microbiota thus influence host-fungus specificity, and the selection of specific fungal strains at the start of a new colony. We argue that we need to expand the current bipartite insect-biased view of the mutualism of fungus-growing termites and include the possible role of bacteria and the benefit for the fungi to fully understand the division of labor among

  1. Type 2 diabetes: the genetic conflict hypothesis.

    PubMed

    Denic, S; Emerald, S; Nicholls, M G

    2013-04-01

    We propose that conflict between paternally and maternally derived genes in the fetus explains three apparently unrelated observations in epidemiological studies of type 2 diabetes mellitus (DM2): (i) low birth weight is a risk factor for the development of DM2, (ii) there is a high prevalence of low birth weight among babies of fathers who develop DM2, and (iii) an exceptionally high prevalence of DM2 exists in modern day Arabs. Genetic conflict is caused by a particular relationship between the parents, their genes and their offspring: (i) mothers are sometimes polyandrous i.e. have children with more than one man, (ii) mothers provide more biological resources to the fetus than fathers, and (iii) the genes that regulate fetal growth come from both parents and both sets of genes determine the use of resources which are only those of the mother. There is a tendency for maternally derived genes (that promote fetal growth) to be suppressed, in order to spare use of mother's resources, while the same paternally derived genes tend to be expressed (to enhance use of the mother's resources). These same genes are pleiotropic: they affect not only fetal growth (birth weight) but also insulin resistance and hence the development of DM2. Polyandry increases differences in the expression between two parental alleles in the fetus i.e. increases genetic conflict and results in the production of bigger babies whereas monandry has the opposite effect. Consequently, parent-of-origin-biased expression of pleiotropic developmental genes could explain why smaller babies are more common when the fathers have DM2. Similarly less genetic conflict in Arabs (resulting from the tradition of strict monandry, the practice of levirate, and preference for a paternal cousin as spouse) could explain, at least in part, their exceptionally high prevalence of DM2. This hypothesis links human mate selection with the risk of developing DM2. PMID:23374424

  2. The oxidative damage initiation hypothesis for meiosis.

    PubMed

    Hörandl, Elvira; Hadacek, Franz

    2013-12-01

    The maintenance of sexual reproduction in eukaryotes is still a major enigma in evolutionary biology. Meiosis represents the only common feature of sex in all eukaryotic kingdoms, and thus, we regard it a key issue for discussing its function. Almost all asexuality modes maintain meiosis either in a modified form or as an alternative pathway, and facultatively apomictic plants increase frequencies of sexuality relative to apomixis after abiotic stress. On the physiological level, abiotic stress causes oxidative stress. We hypothesize that repair of oxidative damage on nuclear DNA could be a major driving force in the evolution of meiosis. We present a hypothetical model for the possible redox chemistry that underlies the binding of the meiosis-specific protein Spo11 to DNA. During prophase of meiosis I, oxidized sites at the DNA molecule are being targeted by the catalytic tyrosine moieties of Spo11 protein, which acts like an antioxidant reducing the oxidized target. The oxidized tyrosine residues, tyrosyl radicals, attack the phosphodiester bonds of the DNA backbone causing DNA double strand breaks that can be repaired by various mechanisms. Polyploidy in apomictic plants could mitigate oxidative DNA damage and decrease Spo11 activation. Our hypothesis may contribute to explaining various enigmatic phenomena: first, DSB formation outnumbers crossovers and, thus, effective recombination events by far because the target of meiosis may be the removal of oxidative lesions; second, it offers an argument for why expression of sexuality is responsive to stress in many eukaryotes; and third, repair of oxidative DNA damage turns meiosis into an essential characteristic of eukaryotic reproduction. PMID:23995700

  3. Dysregulation of strongyloidiasis: a new hypothesis.

    PubMed Central

    Genta, R M

    1992-01-01

    Few other human parasites are associated with such a diverse spectrum of clinical manifestations as Strongyloides stercoralis, yet the basic biological behavior of this unusually versatile worm, particularly with respect to its ability to cause severe disseminated disease in certain hosts, is poorly understood. The current uncritical acceptance of the theory that cell-mediated immunity controls autoinfection has stifled research in other directions. After reviewing what is and is not known about the parasite's behavior in its host, this article explores some of the mechanisms that could be involved in the regulation of the parasite population. Taking the provocative viewpoint that the parasite, not the host, is mainly responsible for the maintenance of a balanced relationship between the two, I propose a new theory that corticosteroids may act on the intraintestinal larvae as molting hormones and directly promote the development of disseminated disease. PMID:1423214

  4. Individual differences in auditory abilities.

    PubMed

    Kidd, Gary R; Watson, Charles S; Gygi, Brian

    2007-07-01

    Performance on 19 auditory discrimination and identification tasks was measured for 340 listeners with normal hearing. Test stimuli included single tones, sequences of tones, amplitude-modulated and rippled noise, temporal gaps, speech, and environmental sounds. Principal components analysis and structural equation modeling of the data support the existence of a general auditory ability and four specific auditory abilities. The specific abilities are (1) loudness and duration (overall energy) discrimination; (2) sensitivity to temporal envelope variation; (3) identification of highly familiar sounds (speech and nonspeech); and (4) discrimination of unfamiliar simple and complex spectral and temporal patterns. Examination of Scholastic Aptitude Test (SAT) scores for a large subset of the population revealed little or no association between general or specific auditory abilities and general intellectual ability. The findings provide a basis for research to further specify the nature of the auditory abilities. Of particular interest are results suggestive of a familiar sound recognition (FSR) ability, apparently specialized for sound recognition on the basis of limited or distorted information. This FSR ability is independent of normal variation in both spectral-temporal acuity and of general intellectual ability. PMID:17614500

  5. Nature versus Nurture in Determining Athletic Ability.

    PubMed

    Yan, Xu; Papadimitriou, Ioannis; Lidor, Ronnie; Eynon, Nir

    2016-01-01

    This overview provides a general discussion of the roles of nature and nurture in determining human athletic ability. On the nature (genetics) side, a review is provided with emphasis on the historical research and on several areas which are likely to be important for future research, including next-generation sequencing technologies. In addition, a number of well-designed training studies that could possibly reveal the biological mechanism ('cause') behind the association between gene variants and athletic ability are discussed. On the nurture (environment) side, we discuss common environmental variables including deliberate practice, family support, and the birthplace effect, which may be important in becoming an elite athlete. Developmental effects are difficult to disassociate with genetic effects, because the early life environment may have long-lasting effects in adulthood. With this in mind, the fetal programming hypothesis is also briefly reviewed, as fetal programming provides an excellent example of how the environment interacts with genetics. We conclude that the traditional argument of nature versus nurture is no longer relevant, as it has been clearly established that both are important factors in the road to becoming an elite athlete. With the availability of the next-generation genetics (sequencing) techniques, it is hoped that future studies will reveal the relevant genes influencing performance, as well as the interaction between those genes and environmental (nurture) factors. PMID:27287074

  6. Attempting to Unravel the Australian Megatsunami Hypothesis

    NASA Astrophysics Data System (ADS)

    Goff, J. R.

    2008-12-01

    Nearly two decades of information report apparent megatsunamis along the SE coast of Australia and yet these interpretations are still highly controversial. This work has proven to be particularly influential in guiding more recent megatsunami researchers, and yet it has never been critically evaluated in the light of recent advances in tsunami research. Much of the controversy hinges upon the nature of the original observations, event chronologies, and source identification. The most recent incarnation of the megatsunami hypothesis is indicative of the controversy. A supposed impact crater to the SW of New Zealand is linked with abandoned Maori settlements, Maori legends, and high elevation beach sand deposits in New Zealand, and apparent megatsunami evidence in eastern Australia and on Lord Howe Island. A date of around AD1500 is proposed. There are two key issues here. First, is there currently any evidence for contemporaneous trans Tasman palaeotsunamis (or megatsunamis) in the Holocene? Second, how reliable is the evidence? The first issue was addressed by comparing Holocene events from the Australian and New Zealand palaeotsunami databases. Up to five possible contemporaneous events were identified, but at the same time flaws in the underpinning data were highlighted. To start with, there is no consistent approach to the interpretation of chronological information comprising the databases. A consistent recalibration of all available radiocarbon data was carried out for both databases. This was based upon information contained in the relevant original papers. No clusters of radiocarbon ages were found for apparent megatsunami deposits along the SE coast of Australia. Clusters were found however, in New Zealand for inferred local and regional events. Next, the nature and extent of physical evidence used to determine tsunami emplacement were found to be highly variable. A preliminary reassessment of the physical evidence casts doubt upon the interpretation of

  7. The Zinc Dyshomeostasis Hypothesis of Alzheimer's Disease

    PubMed Central

    Craddock, Travis J. A.; Tuszynski, Jack A.; Chopra, Deepak; Casey, Noel; Goldstein, Lee E.; Hameroff, Stuart R.; Tanzi, Rudolph E.

    2012-01-01

    Alzheimer's disease (AD) is the most common form of dementia in the elderly. Hallmark AD neuropathology includes extracellular amyloid plaques composed largely of the amyloid-β protein (Aβ), intracellular neurofibrillary tangles (NFTs) composed of hyper-phosphorylated microtubule-associated protein tau (MAP-tau), and microtubule destabilization. Early-onset autosomal dominant AD genes are associated with excessive Aβ accumulation, however cognitive impairment best correlates with NFTs and disrupted microtubules. The mechanisms linking Aβ and NFT pathologies in AD are unknown. Here, we propose that sequestration of zinc by Aβ-amyloid deposits (Aβ oligomers and plaques) not only drives Aβ aggregation, but also disrupts zinc homeostasis in zinc-enriched brain regions important for memory and vulnerable to AD pathology, resulting in intra-neuronal zinc levels, which are either too low, or excessively high. To evaluate this hypothesis, we 1) used molecular modeling of zinc binding to the microtubule component protein tubulin, identifying specific, high-affinity zinc binding sites that influence side-to-side tubulin interaction, the sensitive link in microtubule polymerization and stability. We also 2) performed kinetic modeling showing zinc distribution in extra-neuronal Aβ deposits can reduce intra-neuronal zinc binding to microtubules, destabilizing microtubules. Finally, we 3) used metallomic imaging mass spectrometry (MIMS) to show anatomically-localized and age-dependent zinc dyshomeostasis in specific brain regions of Tg2576 transgenic, mice, a model for AD. We found excess zinc in brain regions associated with memory processing and NFT pathology. Overall, we present a theoretical framework and support for a new theory of AD linking extra-neuronal Aβ amyloid to intra-neuronal NFTs and cognitive dysfunction. The connection, we propose, is based on β-amyloid-induced alterations in zinc ion concentration inside neurons affecting stability of polymerized

  8. Assessing Highly-Creative Ability

    ERIC Educational Resources Information Center

    Cowdroy, Rob; de Graaff, Erik

    2005-01-01

    This paper presents a psychological perspective of the educational dilemma of assessing highly (high-level) creative ability (with some connections to contemporary philosophical debate). Assessment of highly-creative ability is a topic of longstanding debate involving questions of what constitutes creativity; whether the creative mental process is…

  9. Diver First Class Reading Ability.

    ERIC Educational Resources Information Center

    Bain, E. C., III; Berghage, T. E.

    The Nelson-Denny reading test was administered to thirty Navy first class diver candidates to evaluate the group's vocabulary, reading comprehension, reading rate and over-all reading ability. Reading rate and comprehension were at the twelfth grade level, while vocabulary ability was equal to the college freshman norm. (Author)

  10. Egocentrism and Map Reading Ability.

    ERIC Educational Resources Information Center

    Towler, John O.

    Egocentrism was investigated as an influencing factor in the development of the perceptual abilities needed to understand and interpret topographic maps. Attainment of an adequate concept of space, and the ability to accurately perceive spatial relationships (perspectives) are considered fundamental. Piaget and Inhelder identified three stages of…

  11. Implicit Learning as an Ability

    ERIC Educational Resources Information Center

    Kaufman, Scott Barry; DeYoung, Caroline G.; Gray, Jeremy R.; Jimenez, Luis; Brown, Jamie; Mackintosh, Nicholas

    2010-01-01

    The ability to automatically and implicitly detect complex and noisy regularities in the environment is a fundamental aspect of human cognition. Despite considerable interest in implicit processes, few researchers have conceptualized implicit learning as an ability with meaningful individual differences. Instead, various researchers (e.g., Reber,…

  12. Ability Measurement: Conventional or Adaptive?

    ERIC Educational Resources Information Center

    Weiss, David J.; Betz, Nancy E.

    Research to date on adaptive (sequential, branched, individualized, tailored, programmed, response-contingent) ability testing is reviewed and summarized, following a brief review of problems inherent in conventional individual and group approaches to ability measurement. Research reviewed includes empirical, simulation and theoretical studies of…

  13. The Measurement of Translation Ability.

    ERIC Educational Resources Information Center

    Stansfield, Charles W.; And Others

    1992-01-01

    Variables that constitute translation ability are discussed, based on a two-year development and validation study of job-related tests of translation ability for the Federal Bureau of Investigation. The project involved the development of two parallel forms of the Spanish into English Verbatim Translation Exam (SEVTE). (five references) (LB)

  14. Scientific Reasoning in Early and Middle Childhood: The Development of Domain-General Evidence Evaluation, Experimentation, and Hypothesis Generation Skills

    ERIC Educational Resources Information Center

    Piekny, Jeanette; Maehler, Claudia

    2013-01-01

    According to Klahr's (2000, 2005; Klahr & Dunbar, 1988) Scientific Discovery as Dual Search model, inquiry processes require three cognitive components: hypothesis generation, experimentation, and evidence evaluation. The aim of the present study was to investigate (a) when the ability to evaluate perfect covariation, imperfect…

  15. Hypothesis-Driven Candidate Genes for Schizophrenia Compared to Genome-Wide Association Results

    PubMed Central

    Collins, Ann L.; Kim, Yunjung; Sklar, Pamela; O’Donovan, Michael C.; Sullivan, Patrick F.

    2014-01-01

    Background Candidate gene studies have been a key approach to the genetics of schizophrenia. Results of these studies have been confusing and no genes have been unequivocally implicated. The hypothesis-driven candidate gene literature can be appraised via comparison with the results of genome-wide association studies (GWAS). Methods We described the characteristics of hypothesis-driven candidate gene studies from SZGene, and used pathway analysis to compare hypothesis-driven candidate genes with GWAS results from the International Schizophrenia Consortium (ISC). Results SZGene contained 732 autosomal genes evaluated in 1,374 studies. These genes had poor statistical power to detect genetic effects typical for human diseases, assessed only 3.7% of genes in the genome, and had low marker densities per gene. Most genes were assessed once or twice (76.9%), providing minimal ability to evaluate consensus across studies. The ISC had power of 89% to detect a genetic effect typical for common human diseases and assessed 79% of known autosomal common genetic variation. Pathway analyses did not reveal enrichment of smaller ISC p-values in hypothesis-driven candidate genes nor did a comprehensive evaluation of meta-hypotheses driving candidate gene selection (schizophrenia as a disease of the synapse or neurodevelopment). The most studied hypothesis-driven candidate genes had no notable ISC results (COMT, DRD3, DRD2, HTR2A, NRG1, BDNF, DTNBP1, and SLC6A4). Conclusions We did not find support for the idea that the hypothesis-driven candidate genes studied in the literature were enriched for common variation involved in the etiology of schizophrenia. Larger samples are required definitively to evaluate this conclusion. PMID:21854684

  16. The Younger Dryas impact hypothesis: a critical review

    NASA Astrophysics Data System (ADS)

    van Hoesel, Annelies; Hoek, Wim Z.; Pennock, Gillian M.; Drury, Martyn R.

    2014-01-01

    The Younger Dryas impact hypothesis suggests that multiple extraterrestrial airbursts or impacts resulted in the Younger Dryas cooling, extensive wildfires, megafaunal extinctions and changes in human population. After the hypothesis was first published in 2007, it gained much criticism, as the evidence presented was either not indicative of an extraterrestrial impact or not reproducible by other groups. Only three years after the hypothesis had been presented, a requiem paper was published. Despite this, the controversy continues. New evidence, both in favour and against the hypothesis, continues to be published.

  17. Latent ability: grades and test scores systematically underestimate the intellectual ability of negatively stereotyped students.

    PubMed

    Walton, Gregory M; Spencer, Steven J

    2009-09-01

    Past research has assumed that group differences in academic performance entirely reflect genuine differences in ability. In contrast, extending research on stereotype threat, we suggest that standard measures of academic performance are biased against non-Asian ethnic minorities and against women in quantitative fields. This bias results not from the content of performance measures, but from the context in which they are assessed-from psychological threats in common academic environments, which depress the performances of people targeted by negative intellectual stereotypes. Like the time of a track star running into a stiff headwind, such performances underestimate the true ability of stereotyped students. Two meta-analyses, combining data from 18,976 students in five countries, tested this latent-ability hypothesis. Both meta-analyses found that, under conditions that reduce psychological threat, stereotyped students performed better than nonstereotyped students at the same level of past performance. We discuss implications for the interpretation of and remedies for achievement gaps. PMID:19656335

  18. Gender Differences in Academic Achievement: Is Writing an Exception to the Gender Similarities Hypothesis?

    PubMed

    Reynolds, Matthew R; Scheiber, Caroline; Hajovsky, Daniel B; Schwartz, Bryanna; Kaufman, Alan S

    2015-01-01

    The gender similarities hypothesis by J. S. Hyde ( 2005 ), based on large-scale reviews of studies, concludes that boys and girls are more alike than different on most psychological variables, including academic skills such as reading and math (J. S. Hyde, 2005 ). Writing is an academic skill that may be an exception. The authors investigated gender differences in academic achievement using a large, nationally stratified sample of children and adolescents ranging from ages 7-19 years (N = 2,027). Achievement data were from the conormed sample for the Kaufman intelligence and achievement tests. Multiple-indicator, multiple-cause, and multigroup mean and covariance structure models were used to test for mean differences. Girls had higher latent reading ability and higher scores on a test of math computation, but the effect sizes were consistent with the gender similarities hypothesis. Conversely, girls scored higher on spelling and written expression, with effect sizes inconsistent with the gender similarities hypothesis. The findings remained the same after controlling for cognitive ability. Girls outperform boys on tasks of writing. PMID:26135387

  19. The XY Gene Hypothesis of Psychosis: Origins and Current Status

    PubMed Central

    Crow, Timothy J

    2013-01-01

    Sex differences in psychosis and their interaction with laterality (systematic departures from 50:50 left-right symmetry across the antero-posterior neural axis) are reviewed in the context of the X-Y gene hypothesis. Aspects of laterality (handedness/cerebral asymmetry/the torque) predict (1) verbal and non-verbal ability in childhood and across adult life and (2) anatomical, physiological, and linguistic variation relating to psychosis. Neuropsychological and MRI evidence from individuals with sex chromosome aneuploidies indicates that laterality is associated with an X-Y homologous gene pair. Within each mammalian species the complement of such X-Y gene pairs reflects their potential to account for taxon-specific sexual dimorphisms. As a consequence of the mechanism of meiotic suppression of unpaired chromosomes such X-Y gene pairs generate epigenetic variation around a species defining motif that is carried to the zygote with potential to initiate embryonic gene expression in XX or XY format. The Protocadherin11XY (PCDH11XY) gene pair in Xq21.3/Yp11.2 in probable coordination with a gene or genes within PAR2 (the second pseudo-autosomal region) is the prime candidate in relation to cerebral asymmetry and psychosis in Homo sapiens. The lately-described pattern of sequence variation associated with psychosis on the autosomes may reflect a component of the human genome's adjustment to selective pressures generated by the sexually dimorphic mate recognition system. © 2013 The Authors. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics Published by John Wiley and Sons, Ltd. PMID:24123874

  20. Anxiety vulnerability in women: a two-hit hypothesis.

    PubMed

    Catuzzi, Jennifer E; Beck, Kevin D

    2014-09-01

    Females are twice as likely to develop an anxiety disorder compared to males, and thus, are believed to possess an innate vulnerability that increases their susceptibility to develop an anxiety disorder. However, studies using aversive learning paradigms to model anxiety disorders in humans and animals have revealed contradictory results. While females exhibit the ability to rapidly acquire stimulus-response associations, which may result from a greater attentional bias towards threat, females are also capable to readily extinguish these associations. Thus, there is little evidence to suggest that the female sex represents a vulnerability factor of anxiety, per se. However, if females are to possess a second vulnerability factor that increases the inflexibility of stimulus-response associations, then an anxiety disorder may be more likely to develop. Behavioral inhibition (BI) is a vulnerability factor associated with the formation of inflexible stimulus-response associations. In this "two hit" model of anxiety vulnerability, females possessing a BI temperament will rapidly acquire stimulus-response associations that are resistant to extinction, resulting in the development of an anxiety disorder. In this review we explore evidence for a "two-hit" hypothesis underlying anxiety vulnerability in females. We explore the literature for evidence of a sex difference in attentional bias towards threat that may lead to the facilitated acquisition of stimulus-response associations in females. We also provide evidence that BI is associated with inflexible stimulus-response association formation. We conclude with data generated from our laboratory that highlights the additive effect of the female sex and behavioral inhibition vulnerabilities using a model behavior for anxiety disorder-susceptibility, active avoidance. PMID:24518489

  1. [Driving ability with multiple sclerosis].

    PubMed

    Küst, J; Dettmers, C

    2014-07-01

    Driving is an important issue for young patients, especially for those whose walking capacity is impaired. Driving might support the patient's social and vocational participation. The question as to whether a patient with multiple sclerosis (MS) is restricted in the ability to drive a car depends on neurological and neuropsychological deficits, self-awareness, insight into deficits and ability to compensate for loss of function. Because of the enormous variability of symptoms in MS the question is highly individualized. A practical driving test under supervision of a driving instructor (possibly accompanied by a neuropsychologist) might be helpful in providing both patient and relatives adequate feedback on driving abilities. PMID:24906536

  2. Introduction: revisiting the "negrito" hypothesis: a transdisciplinary approach to human prehistory in southeast Asia.

    PubMed

    Endicott, Phillip

    2013-01-01

    The "negrito" hypothesis predicts that a shared phenotype among various contemporary groups of hunter-gatherers in Southeast Asia--dark skin, short stature, tight curly hair--is due to common descent from a region-wide, pre-Neolithic substrate of humanity. The alternative is that their distinctive phenotype results from convergent evolution. The core issues of the negrito hypothesis are today more relevant than ever to studies of human evolution, including the out-of-Africa migration, admixture with Denisovans, and the effects of environment and ecology on life-history traits. Understanding the current distribution of the negrito phenotype dictates a wide-ranging remit for study, including the articulation of the relationship between foragers and farmers in the present, the development of settled agriculture in the mid-Holocene, and terminal Pleistocene population expansions. The consensus reached by the contributors to this special double issue of Human Biology is that there is not yet conclusive evidence either for or against the negrito hypothesis. Nevertheless, the process of revisiting the problem will benefit the knowledge of the human prehistory of Southeast Asia. Whether the term negrito accurately reflects the all-encompassing nature of the resulting inquiry is in itself questionable, but the publication of this double issue is testament to the enduring ability of this hypothesis to unite disparate academic disciplines in a common purpose. PMID:24297218

  3. Revisiting the Continuum Hypothesis: Toward an In-Depth Exploration of Executive Functions in Korsakoff Syndrome

    PubMed Central

    Brion, Mélanie; Pitel, Anne-Lise; Beaunieux, Hélène; Maurage, Pierre

    2014-01-01

    Korsakoff syndrome (KS) is a neurological state mostly caused by alcohol-dependence and leading to disproportionate episodic memory deficits. KS patients present more severe anterograde amnesia than Alcohol-Dependent Subjects (ADS), which led to the continuum hypothesis postulating a progressive increase in brain and cognitive damages during the evolution from ADS to KS. This hypothesis has been extensively examined for memory but is still debated for other abilities, notably executive functions (EF). EF have up to now been explored by unspecific tasks in KS, and few studies explored their interactions with memory. Exploring EF in KS by specific tasks based on current EF models could thus renew the exploration of the continuum hypothesis. This paper will propose a research program aiming at: (1) clarifying the extent of executive dysfunctions in KS by tasks focusing on specific EF subcomponents; (2) determining the differential EF deficits in ADS and KS; (3) exploring EF-memory interactions in KS with innovative tasks. At the fundamental level, this exploration will test the continuum hypothesis beyond memory. At the clinical level, it will propose new rehabilitation tools focusing on the EF specifically impaired in KS. PMID:25071526

  4. Revisiting the continuum hypothesis: toward an in-depth exploration of executive functions in korsakoff syndrome.

    PubMed

    Brion, Mélanie; Pitel, Anne-Lise; Beaunieux, Hélène; Maurage, Pierre

    2014-01-01

    Korsakoff syndrome (KS) is a neurological state mostly caused by alcohol-dependence and leading to disproportionate episodic memory deficits. KS patients present more severe anterograde amnesia than Alcohol-Dependent Subjects (ADS), which led to the continuum hypothesis postulating a progressive increase in brain and cognitive damages during the evolution from ADS to KS. This hypothesis has been extensively examined for memory but is still debated for other abilities, notably executive functions (EF). EF have up to now been explored by unspecific tasks in KS, and few studies explored their interactions with memory. Exploring EF in KS by specific tasks based on current EF models could thus renew the exploration of the continuum hypothesis. This paper will propose a research program aiming at: (1) clarifying the extent of executive dysfunctions in KS by tasks focusing on specific EF subcomponents; (2) determining the differential EF deficits in ADS and KS; (3) exploring EF-memory interactions in KS with innovative tasks. At the fundamental level, this exploration will test the continuum hypothesis beyond memory. At the clinical level, it will propose new rehabilitation tools focusing on the EF specifically impaired in KS. PMID:25071526

  5. On interpretation and task selection: the sub-component hypothesis of cognitive noise effects

    PubMed Central

    Sörqvist, Patrik

    2015-01-01

    It is often argued that the effects of noise on a “complex ability” (e.g., reading, writing, calculation) can be explained by the impairment noise causes to some ability (e.g., working memory) upon which the complex ability depends. Because of this, tasks that measure “sub-component abilities” (i.e., those abilities upon which complex abilities depend) are often deemed sufficient in cognitive noise studies, even when the primary interest is to understand the effects of noise as they arise in applied settings (e.g., offices and schools). This approach can be called the “sub-component hypothesis of cognitive noise effects.” The present paper discusses two things that are troublesome for this approach: difficulties with interpretation and generalizability. A complete understanding of the effects of noise on complex abilities requires studying the complex ability itself. Cognitive noise researches must, therefore, employ tasks that mimic the tasks that are actually carried out in the applied setting to which the results are intended to be generalized. Tasks that measure “sub-component abilities” may be complementary, but should not be given priority in applied cognitive research. PMID:25642207

  6. About the structure of cellulose: debating the Lindman hypothesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The hypothesis advanced in this issue of Cellulose, that the solubility or insolubility characteristics of cellulose are significantly based upon amphiphilic and hydrophobic molecular interactions, is bound to shake the roots of (some of) our textbook wisdom. The hypothesis is based on the considera...

  7. Longitudinal Dimensionality of Adolescent Psychopathology: Testing the Differentiation Hypothesis

    ERIC Educational Resources Information Center

    Sterba, Sonya K.; Copeland, William; Egger, Helen L.; Costello, E. Jane; Erkanli, Alaattin; Angold, Adrian

    2010-01-01

    Background: The differentiation hypothesis posits that the underlying liability distribution for psychopathology is of low dimensionality in young children, inflating diagnostic comorbidity rates, but increases in dimensionality with age as latent syndromes become less correlated. This hypothesis has not been adequately tested with longitudinal…

  8. Token Women: An Empirical Test of Kanter's Hypothesis

    ERIC Educational Resources Information Center

    Spangler, Eve; And Others

    1978-01-01

    This study compared female students in a male-dominated law school with female students in a law school where the percentage of women was higher in order to test the hypothesis that the minority-to-minority ratio is a significant determinant of minority member achievement. Results were found to support the hypothesis. (Author/BC)

  9. The Regression Hypothesis as a Framework for First Language Attrition

    ERIC Educational Resources Information Center

    Keijzer, Merel

    2010-01-01

    In an attempt to explain first language attrition in emigrant populations, this paper investigates the explanatory power of a framework that has--until now--received little attention: the regression hypothesis (Jakobson, 1941). This hypothesis predicts that the order of attrition is the reverse of the order of acquisition. The regression…

  10. Age Dedifferentiation Hypothesis: Evidence form the WAIS III.

    ERIC Educational Resources Information Center

    Juan-Espinosa, Manuel; Garcia, Luis F.; Escorial, Sergio; Rebollo, Irene; Colom, Roberto; Abad, Francisco J.

    2002-01-01

    Used the Spanish standardization of the Wechsler Adult Intelligence Scale III (WAIS III) (n=1,369) to test the age dedifferentiation hypothesis. Results show no changes in the percentage of variance accounted for by "g" and four group factors when restriction of range is controlled. Discusses an age indifferentation hypothesis. (SLD)

  11. Assess the Critical Period Hypothesis in Second Language Acquisition

    ERIC Educational Resources Information Center

    Du, Lihong

    2010-01-01

    The Critical Period Hypothesis aims to investigate the reason for significant difference between first language acquisition and second language acquisition. Over the past few decades, researchers carried out a series of studies to test the validity of the hypothesis. Although there were certain limitations in these studies, most of their results…

  12. Making Knowledge Delivery Failsafe: Adding Step Zero in Hypothesis Testing

    ERIC Educational Resources Information Center

    Pan, Xia; Zhou, Qiang

    2010-01-01

    Knowledge of statistical analysis is increasingly important for professionals in modern business. For example, hypothesis testing is one of the critical topics for quality managers and team workers in Six Sigma training programs. Delivering the knowledge of hypothesis testing effectively can be an important step for the incapable learners or…

  13. An Exercise for Illustrating the Logic of Hypothesis Testing

    ERIC Educational Resources Information Center

    Lawton, Leigh

    2009-01-01

    Hypothesis testing is one of the more difficult concepts for students to master in a basic, undergraduate statistics course. Students often are puzzled as to why statisticians simply don't calculate the probability that a hypothesis is true. This article presents an exercise that forces students to lay out on their own a procedure for testing a…

  14. Teacher Satisfaction and Dissatisfaction: Herzberg's 'Two-Factor' Hypothesis Revisited.

    ERIC Educational Resources Information Center

    Nias, Jennifer

    1981-01-01

    Discusses a study undertaken to evaluate perceptions of job satisfaction and dissatisfaction among 100 graduates trained to teach in primary schools. Weighs findings in light of a hypothesis (Herzberg's two-factor hypothesis) which states that causes of job satisfaction are substantially independent of those determining job dissatisfaction.…

  15. Marital Stability and Spouses' Shared Time: A Multidisciplinary Hypothesis.

    ERIC Educational Resources Information Center

    Hill, Martha S.

    1988-01-01

    Tested hypothesis that spouses' shared leisure time is form of pleasurable interaction that strengthens attachment between them and helps prevent marital dissolution. Empirical tests supported attachment hypothesis and suggest that, because couples with children have less shared leisure time, children can contribute to marital dissolution as well…

  16. Further Evidence for the Cultural Norm Hypothesis: Positive Emotion in Depressed and Control European American and Asian American Women

    PubMed Central

    Chentsova-Dutton, Yulia E.; Tsai, Jeanne L.; Gotlib, Ian H.

    2010-01-01

    How does culture shape the experience and expression of depression? Previously we observed that depression dampened negative emotional responses in European Americans, but increased negative emotional responses in Asian Americans (Chentsova-Dutton et al., 2007). We interpreted these findings as support for the cultural norm hypothesis, which predicts that depression reduces individuals’ abilities to react in culturally normative or ideal ways (i.e., disrupting European Americans’ abilities to express their emotions openly and Asian Americans’ abilities to moderate and control their emotions). In the present study, we examined the generalizability of the cultural norm hypothesis to positive emotion. We measured the emotional reactivity of 35 European Americans (17 depressed, 18 controls) and 31 Asian Americans (15 depressed, 16 controls) to an amusing film clip. Consistent with the cultural norm hypothesis, depressed European Americans showed dampened positive emotional reactivity (i.e., fewer enjoyment and non-enjoyment smiles, less intense reports of positive emotion, lower cardiac activation) compared to control European Americans, whereas depressed Asian Americans showed similar (i.e., smiles, reports of positive emotion), and even greater (i.e., higher cardiac activation) positive emotional reactivity compared to control Asian Americans. These findings suggest that the cultural norm hypothesis generalizes to the experience and expression of positive emotion. PMID:20438167

  17. A Graph-Based Recovery and Decomposition of Swanson’s Hypothesis using Semantic Predications

    PubMed Central

    Cameron, Delroy; Bodenreider, Olivier; Yalamanchili, Hima; Danh, Tu; Vallabhaneni, Sreeram; Thirunarayan, Krishnaprasad; Sheth, Amit P.; Rindflesch, Thomas C.

    2014-01-01

    Objectives This paper presents a methodology for recovering and decomposing Swanson’s Raynaud Syndrome–Fish Oil Hypothesis semi-automatically. The methodology leverages the semantics of assertions extracted from biomedical literature (called semantic predications) along with structured background knowledge and graph-based algorithms to semi-automatically capture the informative associations originally discovered manually by Swanson. Demonstrating that Swanson’s manually intensive techniques can be undertaken semi-automatically, paves the way for fully automatic semantics-based hypothesis generation from scientific literature. Methods Semantic predications obtained from biomedical literature allow the construction of labeled directed graphs which contain various associations among concepts from the literature. By aggregating such associations into informative subgraphs, some of the relevant details originally articulated by Swanson has been uncovered. However, by leveraging background knowledge to bridge important knowledge gaps in the literature, a methodology for semi-automatically capturing the detailed associations originally explicated in natural language by Swanson has been developed. Results Our methodology not only recovered the 3 associations commonly recognized as Swanson’s Hypothesis, but also decomposed them into an additional 16 detailed associations, formulated as chains of semantic predications. Altogether, 14 out of the 19 associations that can be attributed to Swanson were retrieved using our approach. To the best of our knowledge, such an in-depth recovery and decomposition of Swanson’s Hypothesis has never been attempted. Conclusion In this work therefore, we presented a methodology for semi- automatically recovering and decomposing Swanson’s RS-DFO Hypothesis using semantic representations and graph algorithms. Our methodology provides new insights into potential prerequisites for semantics-driven Literature-Based Discovery (LBD

  18. Childhood Mental Ability and Lifetime Psychiatric Contact: A 66-Year Follow-Up Study of the 1932 Scottish Mental Ability Survey.

    ERIC Educational Resources Information Center

    Walker, Nicholas P.; McConville, Pauline M; Hunter, David; Deary, Ian J.; Whalley, Lawrence J.

    2002-01-01

    Tested the hypothesis that intelligence is related to the risk of mental illness by linking childhood mental ability data to registers of psychiatric contact in a stable population of 4,199 adults in Scotland. Findings show intelligence to be an independent predictor of psychiatric contact, with each standard deviation decrease in IQ resulting in…

  19. Inhibitory Control Predicts Grammatical Ability

    PubMed Central

    Ibbotson, Paul; Kearvell-White, Jennifer

    2015-01-01

    We present evidence that individual variation in grammatical ability can be predicted by individual variation in inhibitory control. We tested 81 5-year-olds using two classic tests from linguistics and psychology (Past Tense and the Stroop). Inhibitory control was a better predicator of grammatical ability than either vocabulary or age. Our explanation is that giving the correct response in both tests requires using a common cognitive capacity to inhibit unwanted competition. The implications are that understanding the developmental trajectory of language acquisition can benefit from integrating the developmental trajectory of non-linguistic faculties, such as executive control. PMID:26659926

  20. Out-of-sequence measurement updates for multi-hypothesis tracking algorithms

    NASA Astrophysics Data System (ADS)

    Chan, Stephanie; Paffenroth, Randy

    2008-04-01

    In multi-sensor tracking systems, observations are often exchanged over a network for processing. Network delays create situations in which measurements arrive out-of-sequence. The out-of-sequence measurement (OOSM) update problem is of particular significance in networked multiple hypothesis tracking (MHT) algorithms. The advantage of MHT is the ability to revoke past measurement assignment decisions as future information becomes available. Accordingly, we not only have to deal with network delays for initial assignment, but must also address delayed assignment revocations. We study the performance of extant algorithms and two algorithm modifications for the purpose of OOSM filtering in MHT architectures.

  1. Phasic acetylcholine release and the volume transmission hypothesis: time to move on

    PubMed Central

    Sarter, Martin; Parikh, Vinay; Howe, W. Matthew

    2009-01-01

    Traditional descriptions of the cortical cholinergic input system focused on the diffuse organization of cholinergic projections and the hypothesis that slowly changing levels of extracellular acetylcholine (ACh) mediate different arousal states. The ability of ACh to reach the extrasynaptic space (volume neurotransmission), as opposed to remaining confined to the synaptic cleft (wired neurotransmission), has been considered an integral component of this conceptualization. Recent studies demonstrated that phasic release of ACh, at the scale of seconds, mediates precisely defined cognitive operations. This characteristic of cholinergic neurotransmission is proposed to be of primary importance for understanding cholinergic function and developing treatments for cognitive disorders that result from abnormal cholinergic neurotransmission. PMID:19377503

  2. Particle probability hypothesis density filtering for multitarget visual tracking with robust state extraction

    NASA Astrophysics Data System (ADS)

    Wu, Jingjing; Hu, Shiqiang; Wang, Yang

    2011-09-01

    Particle probability hypothesis density (PHD) filter-based visual trackers have achieved considerable success in the visual tracking field. But position measurements based on detection may not have enough ability to discriminate an object from clutter, and accurate state extraction cannot be obtained in the original PHD filtering framework, especially when targets can appear, disappear, merge, or split at any time. To meet the limitations, the proposed algorithm combines a color histogram of a target and the temporal dynamics in a unifying framework and a Gaussian mixture model clustering method for efficient state extraction is designed. The proposed tracker can improve the accuracy of state estimation in tracking a variable number of objects.

  3. Vehicle Detection Based on Probability Hypothesis Density Filter

    PubMed Central

    Zhang, Feihu; Knoll, Alois

    2016-01-01

    In the past decade, the developments of vehicle detection have been significantly improved. By utilizing cameras, vehicles can be detected in the Regions of Interest (ROI) in complex environments. However, vision techniques often suffer from false positives and limited field of view. In this paper, a LiDAR based vehicle detection approach is proposed by using the Probability Hypothesis Density (PHD) filter. The proposed approach consists of two phases: the hypothesis generation phase to detect potential objects and the hypothesis verification phase to classify objects. The performance of the proposed approach is evaluated in complex scenarios, compared with the state-of-the-art. PMID:27070621

  4. Vehicle Detection Based on Probability Hypothesis Density Filter.

    PubMed

    Zhang, Feihu; Knoll, Alois

    2016-01-01

    In the past decade, the developments of vehicle detection have been significantly improved. By utilizing cameras, vehicles can be detected in the Regions of Interest (ROI) in complex environments. However, vision techniques often suffer from false positives and limited field of view. In this paper, a LiDAR based vehicle detection approach is proposed by using the Probability Hypothesis Density (PHD) filter. The proposed approach consists of two phases: the hypothesis generation phase to detect potential objects and the hypothesis verification phase to classify objects. The performance of the proposed approach is evaluated in complex scenarios, compared with the state-of-the-art. PMID:27070621

  5. Biostatistics Series Module 2: Overview of Hypothesis Testing

    PubMed Central

    Hazra, Avijit; Gogtay, Nithya

    2016-01-01

    Hypothesis testing (or statistical inference) is one of the major applications of biostatistics. Much of medical research begins with a research question that can be framed as a hypothesis. Inferential statistics begins with a null hypothesis that reflects the conservative position of no change or no difference in comparison to baseline or between groups. Usually, the researcher has reason to believe that there is some effect or some difference which is the alternative hypothesis. The researcher therefore proceeds to study samples and measure outcomes in the hope of generating evidence strong enough for the statistician to be able to reject the null hypothesis. The concept of the P value is almost universally used in hypothesis testing. It denotes the probability of obtaining by chance a result at least as extreme as that observed, even when the null hypothesis is true and no real difference exists. Usually, if P is < 0.05 the null hypothesis is rejected and sample results are deemed statistically significant. With the increasing availability of computers and access to specialized statistical software, the drudgery involved in statistical calculations is now a thing of the past, once the learning curve of the software has been traversed. The life sciences researcher is therefore free to devote oneself to optimally designing the study, carefully selecting the hypothesis tests to be applied, and taking care in conducting the study well. Unfortunately, selecting the right test seems difficult initially. Thinking of the research hypothesis as addressing one of five generic research questions helps in selection of the right hypothesis test. In addition, it is important to be clear about the nature of the variables (e.g., numerical vs. categorical; parametric vs. nonparametric) and the number of groups or data sets being compared (e.g., two or more than two) at a time. The same research question may be explored by more than one type of hypothesis test. While this may be

  6. Biostatistics Series Module 2: Overview of Hypothesis Testing.

    PubMed

    Hazra, Avijit; Gogtay, Nithya

    2016-01-01

    Hypothesis testing (or statistical inference) is one of the major applications of biostatistics. Much of medical research begins with a research question that can be framed as a hypothesis. Inferential statistics begins with a null hypothesis that reflects the conservative position of no change or no difference in comparison to baseline or between groups. Usually, the researcher has reason to believe that there is some effect or some difference which is the alternative hypothesis. The researcher therefore proceeds to study samples and measure outcomes in the hope of generating evidence strong enough for the statistician to be able to reject the null hypothesis. The concept of the P value is almost universally used in hypothesis testing. It denotes the probability of obtaining by chance a result at least as extreme as that observed, even when the null hypothesis is true and no real difference exists. Usually, if P is < 0.05 the null hypothesis is rejected and sample results are deemed statistically significant. With the increasing availability of computers and access to specialized statistical software, the drudgery involved in statistical calculations is now a thing of the past, once the learning curve of the software has been traversed. The life sciences researcher is therefore free to devote oneself to optimally designing the study, carefully selecting the hypothesis tests to be applied, and taking care in conducting the study well. Unfortunately, selecting the right test seems difficult initially. Thinking of the research hypothesis as addressing one of five generic research questions helps in selection of the right hypothesis test. In addition, it is important to be clear about the nature of the variables (e.g., numerical vs. categorical; parametric vs. nonparametric) and the number of groups or data sets being compared (e.g., two or more than two) at a time. The same research question may be explored by more than one type of hypothesis test. While this may be

  7. A physical-space approach for the probability hypothesis density and cardinalized probability hypothesis density filters

    NASA Astrophysics Data System (ADS)

    Erdinc, Ozgur; Willett, Peter; Bar-Shalom, Yaakov

    2006-05-01

    The probability hypothesis density (PHD) filter, an automatically track-managed multi-target tracker, is attracting increasing but cautious attention. Its derivation is elegant and mathematical, and thus of course many engineers fear it; perhaps that is currently limiting the number of researchers working on the subject. In this paper, we explore a physical-space approach - a bin model - which leads us to arrive the same filter equations as the PHD. Unlike the original derivation of the PHD filter, the concepts used are the familiar ones of conditional probability. The original PHD suffers from a "target-death" problem in which even a single missed detection can lead to the apparent disappearance of a target. To obviate this, PHD originator Mahler has recently developed a new "cardinalized" version of PHD (CPHD). We are able to extend our physical-space derivation to the CPHD case as well. We stress that the original derivations are mathematically correct, and need no embellishment from us; our contribution here is to offer an alternative derivation, one that we find appealing.

  8. Emotional Intelligence and Leadership Abilities

    ERIC Educational Resources Information Center

    Herbst, H. H.; Maree, J. G.; Sibanda, E.

    2006-01-01

    While exceptional leaders share certain qualities like a strong personal ethic and a compelling vision of the future, research has failed to provide conclusive "proof" of the link between a leader's effectiveness and his/ her emotional intelligence (defined from a cognitive perspective, as a set of abilities). Given the increased recognition of…

  9. Performance Equals Ability and What?

    ERIC Educational Resources Information Center

    Dunnette, Marvin D.

    The results of several research studies designed to evaluate different theories of work motivation are presented. Graen (1967), through hiring 169 high school girls to do a clerical task, showed that ability measures can account for far more performance variance than motivation variables such as expectancy and instrumentality. Similar results were…

  10. The Structure of Mathematical Ability.

    ERIC Educational Resources Information Center

    Furneaux, W. D.; Rees, Ruth

    1978-01-01

    A mathematics test and the Thurstone PMA Battery were administered to 225 technical students. The item/item correlations were analyzed using both a principal components and a maximum-likelihood method. After varimax rotation, the same structure emerged from both. Results suggest a "mathematical ability" factor independent of "g." (Author/SJL)

  11. Challenging High-Ability Students

    ERIC Educational Resources Information Center

    Scager, Karin; Akkerman, Sanne F.; Pilot, Albert; Wubbels, Theo

    2014-01-01

    The existing literature on indicators of an optimal learning environment for high-ability students frequently discusses the concept of challenge. It is, however, not clear what, precisely, constitutes appropriate challenge for these students. In this study, the authors examined an undergraduate honours course, Advanced Cell Biology, which has…

  12. Community Influences on Cognitive Ability.

    ERIC Educational Resources Information Center

    Coon, Hilary; And Others

    1992-01-01

    Associations between community environment and cognitive ability were studied in 167 adoptive and 175 nonadoptive Colorado families. Seven families were omitted. A proposed model, tested by census measures, finds several aspects of communities showing environmental relationships with child IQ over parental influences. Rural communities have a…

  13. Ability Grouping and Cooperative Learning.

    ERIC Educational Resources Information Center

    1994

    This collection of articles is intended to demonstrate that there is solid research to justify both ability grouping and cooperative learning with gifted students and that each approach should be used judiciously to address particular student needs. Introductory material describes the philosophy and program policy of the Center for Talented Youth…

  14. Technology and Motor Ability Development

    ERIC Educational Resources Information Center

    Wang, Lin; Lang, Yong; Luo, Zhongmin

    2014-01-01

    As a new member joining the technology family, active video games have been developed to promote physical exercise. This working-in-progress paper shares an ongoing project on examining the basic motor abilities that are enhanced through participating in commercially available active video games. [For the full proceedings see ED557181.

  15. The Assessment of Mathematical Abilities.

    ERIC Educational Resources Information Center

    Osborn, Herbert H.

    1983-01-01

    A test was given to 322 secondary students to develop a profile of mathematical ability based on four components: computation, pattern recognition, logical reasoning, and symbolic manipulation. These profiles were compared to mathematics test scores; the results verified hypotheses about individual differences in mental processes and knowledge…

  16. Competence: Commodification of Human Ability

    ERIC Educational Resources Information Center

    Han, Soonghee

    2008-01-01

    The purpose of this article is to analyze the meaning and presumptions of competence in the concrete context of knowledge capitalism. First, the nature of competence as a "commodification of human ability" that obtains a standardized monetary value to sell in the labor market, is elucidated by applying Karl Marx's critical theory. Second, it is…

  17. Cognitive Abilities of Maltreated Children

    ERIC Educational Resources Information Center

    Viezel, Kathleen D.; Freer, Benjamin D.; Lowell, Ari; Castillo, Jenean A.

    2015-01-01

    School psychologists should be aware of developmental risk factors for children who have been abused or neglected. The present study used the "Wechsler Intelligence Scale for Children, Fourth Edition" to examine the cognitive abilities of 120 children in foster care subsequent to maltreatment. Results indicated that, compared to a…

  18. Learning Anatomy Enhances Spatial Ability

    ERIC Educational Resources Information Center

    Vorstenbosch, Marc A. T. M.; Klaassen, Tim P. F. M.; Donders, A. R. T.; Kooloos, Jan G. M.; Bolhuis, Sanneke M.; Laan, Roland F. J. M.

    2013-01-01

    Spatial ability is an important factor in learning anatomy. Students with high scores on a mental rotation test (MRT) systematically score higher on anatomy examinations. This study aims to investigate if learning anatomy also oppositely improves the MRT-score. Five hundred first year students of medicine ("n" = 242, intervention) and…

  19. Childhood Cognitive Ability: Relationship to Gestational Diabetes Mellitus in India

    PubMed Central

    Veena, S R; Krishnaveni, G V; Srinivasan, K; Kurpad, A V; Muthayya, S; Hill, J C; Kiran, K N; Fall, C H D

    2012-01-01

    Aims/Hypothesis To test the hypothesis that maternal gestational diabetes mellitus (GDM) is associated with poorer cognitive ability in children born to mothers with GDM compared to children born to non-GDM mothers in India. Methods During 1997-98 maternal GDM status was assessed at 30±2 weeks of gestation. Between 2007-2008, at a mean age of 9.7 years, 515 children (32-offspring of GDM mothers (ODM’s); 483-offspring of non-GDM mothers (controls)) from the Mysore Parthenon birth cohort underwent cognitive function assessment using tests from the Kaufman Assessment Battery for children-second edition and additional tests measuring learning, long-term storage/retrieval, short-term memory, reasoning, attention and concentration, visuo-spatial and verbal abilities. Results Compared to controls, ODM’S scored higher in tests for learning, long-term retrieval/storage (p=0.008), reasoning (p=0.02), verbal ability (p=0.01) and attention and concentration (p=0.003). In multiple regression, adjusted for the child’s age, sex, gestation, neonatal weight and head circumference, maternal age, parity, BMI, parent’s socio-economic status, education and rural/urban residence, this difference remained significant only for learning, long-term retrieval/storage (β=0.4SD (95% CI: 0.01, 0.75); p=0.042) and verbal ability (β=0.5SD (95% CI: 0.09, 0.83); p=0.015) and not with other test scores. Conclusions/interpretation In this population of healthy Indian children, there was no evidence of lower cognitive ability in ODM’s. In fact some cognitive scores were higher in ODM’s. PMID:20614102

  20. Alzheimer's disease: the amyloid hypothesis and the Inverse Warburg effect

    PubMed Central

    Demetrius, Lloyd A.; Magistretti, Pierre J.; Pellerin, Luc

    2014-01-01

    Epidemiological and biochemical studies show that the sporadic forms of Alzheimer's disease (AD) are characterized by the following hallmarks: (a) An exponential increase with age; (b) Selective neuronal vulnerability; (c) Inverse cancer comorbidity. The present article appeals to these hallmarks to evaluate and contrast two competing models of AD: the amyloid hypothesis (a neuron-centric mechanism) and the Inverse Warburg hypothesis (a neuron-astrocytic mechanism). We show that these three hallmarks of AD conflict with the amyloid hypothesis, but are consistent with the Inverse Warburg hypothesis, a bioenergetic model which postulates that AD is the result of a cascade of three events—mitochondrial dysregulation, metabolic reprogramming (the Inverse Warburg effect), and natural selection. We also provide an explanation for the failures of the clinical trials based on amyloid immunization, and we propose a new class of therapeutic strategies consistent with the neuroenergetic selection model. PMID:25642192

  1. Alzheimer's disease: the amyloid hypothesis and the Inverse Warburg effect.

    PubMed

    Demetrius, Lloyd A; Magistretti, Pierre J; Pellerin, Luc

    2014-01-01

    Epidemiological and biochemical studies show that the sporadic forms of Alzheimer's disease (AD) are characterized by the following hallmarks: (a) An exponential increase with age; (b) Selective neuronal vulnerability; (c) Inverse cancer comorbidity. The present article appeals to these hallmarks to evaluate and contrast two competing models of AD: the amyloid hypothesis (a neuron-centric mechanism) and the Inverse Warburg hypothesis (a neuron-astrocytic mechanism). We show that these three hallmarks of AD conflict with the amyloid hypothesis, but are consistent with the Inverse Warburg hypothesis, a bioenergetic model which postulates that AD is the result of a cascade of three events-mitochondrial dysregulation, metabolic reprogramming (the Inverse Warburg effect), and natural selection. We also provide an explanation for the failures of the clinical trials based on amyloid immunization, and we propose a new class of therapeutic strategies consistent with the neuroenergetic selection model. PMID:25642192

  2. Using the Gaia Hypothesis to Synthesize an Introductory Biology Course.

    ERIC Educational Resources Information Center

    Baker, Gail A.

    1993-01-01

    The Gaia Hypothesis emphasizes the interactions and feedback mechanisms between the living and nonliving process that take place on Earth. Employing this concept in instruction can emphasize the interdisciplinary nature of science and give a planetary perspective of biology. (PR)

  3. The effect of scale on the applicability of Taylor's hypothesis

    NASA Astrophysics Data System (ADS)

    Parlange, Marc; Higgins, Chad; Froidevaux, Martin; Simeonov, Valentin

    2010-05-01

    Taylor's frozen flow hypothesis is a central assumption in most fluid mechanics experiments with stationary sensors, and many statistical theories of turbulence where links between the Lagrangian and Eulerian nature of turbulence are made. In this work we seek to quantify the effectiveness of Taylor's hypothesis at the field scale using water vapor as a passive tracer. A horizontal Raman Lidar is used to capture the humidity field in space and time above a small lake in Switzerland. High resolution wind speed and direction measurements are conducted simultaneously allowing for a direct test of Taylor's hypothesis. Through a wavelet decomposition of the data we show that scale has a strong influence on the applicability of Taylor's hypothesis. This effect is explained through the use of dimensional analysis and turbulent structure functions, which ultimately leads to the definition of a nondimensional parameter describing the ‘persistency' of the turbulence.

  4. Hypothesis Testing Using the Films of the Three Stooges

    ERIC Educational Resources Information Center

    Gardner, Robert; Davidson, Robert

    2010-01-01

    The use of The Three Stooges' films as a source of data in an introductory statistics class is described. The Stooges' films are separated into three populations. Using these populations, students may conduct hypothesis tests with data they collect.

  5. Menarche and Fatness: Reexamination of the Critical Body Composition Hypothesis

    ERIC Educational Resources Information Center

    Trussell, James

    1978-01-01

    Examines the credibility of the theory that, menarche and fecundity require a certain level of fat in the body. Concludes that the evidence does not totally support this hypothesis and that further investigation is warranted. (GA)

  6. Null but not void: considerations for hypothesis testing.

    PubMed

    Shaw, Pamela A; Proschan, Michael A

    2013-01-30

    Standard statistical theory teaches us that once the null and alternative hypotheses have been defined for a parameter, the choice of the statistical test is clear. Standard theory does not teach us how to choose the null or alternative hypothesis appropriate to the scientific question of interest. Neither does it tell us that in some cases, depending on which alternatives are realistic, we may want to define our null hypothesis differently. Problems in statistical practice are frequently not as pristinely summarized as the classic theory in our textbooks. In this article, we present examples in statistical hypothesis testing in which seemingly simple choices are in fact rich with nuance that, when given full consideration, make the choice of the right hypothesis test much less straightforward. Published 2012. This article is a US Government work and is in the public domain in the USA. PMID:22807023

  7. The Double-Deficit Hypothesis in Spanish Developmental Dyslexia

    ERIC Educational Resources Information Center

    Jimenez, Juan E.; Hernandez-Valle, Isabel; Rodriguez, Cristina; Guzman, Remedios; Diaz, Alicia; Ortiz, Rosario

    2008-01-01

    The double-deficit hypothesis (DDH) of developmental dyslexia was investigated in seven to twelve year old Spanish children. It was observed that the double deficit (DD) group had the greatest difficulty with reading.

  8. On the 'fast electron hypothesis' for stellar flares

    NASA Technical Reports Server (NTRS)

    Mullan, D. J.

    1990-01-01

    It is pointed out that Gurzadyan's (1988) fast-electron hypothesis for stellar flares encounters certain difficulties. The origin of the fast electrons is obscure. Negative flares and predicted ratios of X-ray to optical fluxes are not necessarily a proof of the fast-electron hypothesis. When the electrons thermalize, they will yield X-ray fluxes which are orders of magnitude too large to be consistent with observations.

  9. Geomagnetic field analysis. IV - Testing the frozen-flux hypothesis

    NASA Astrophysics Data System (ADS)

    Bloxham, J.; Gubbins, D.

    1986-01-01

    Magnetic field models at the core-mantle boundary are presented for three epochs: 1959.5, 1969.5, and 1980.0. The hypothesis that the field has been frozen into the core fluid throughout this 20-yr time span is tested by comparing the changes in the flux integrals over the three epochs with error estimates for the field at the core surface. It is found that the hypothesis can be rejected with 95 percent confidence.

  10. Testing the null hypothesis: the forgotten legacy of Karl Popper?

    PubMed

    Wilkinson, Mick

    2013-01-01

    Testing of the null hypothesis is a fundamental aspect of the scientific method and has its basis in the falsification theory of Karl Popper. Null hypothesis testing makes use of deductive reasoning to ensure that the truth of conclusions is irrefutable. In contrast, attempting to demonstrate the new facts on the basis of testing the experimental or research hypothesis makes use of inductive reasoning and is prone to the problem of the Uniformity of Nature assumption described by David Hume in the eighteenth century. Despite this issue and the well documented solution provided by Popper's falsification theory, the majority of publications are still written such that they suggest the research hypothesis is being tested. This is contrary to accepted scientific convention and possibly highlights a poor understanding of the application of conventional significance-based data analysis approaches. Our work should remain driven by conjecture and attempted falsification such that it is always the null hypothesis that is tested. The write up of our studies should make it clear that we are indeed testing the null hypothesis and conforming to the established and accepted philosophical conventions of the scientific method. PMID:23249368

  11. Functional neuroanatomical evidence for the double-deficit hypothesis of developmental dyslexia.

    PubMed

    Norton, Elizabeth S; Black, Jessica M; Stanley, Leanne M; Tanaka, Hiroko; Gabrieli, John D E; Sawyer, Carolyn; Hoeft, Fumiko

    2014-08-01

    The double-deficit hypothesis of dyslexia posits that both rapid naming and phonological impairments can cause reading difficulties, and that individuals who have both of these deficits show greater reading impairments compared to those with a single deficit. Despite extensive behavioral research, the brain basis of poor reading with a double-deficit has never been investigated. The goal of the study was to evaluate the double-deficit hypothesis using functional MRI. Activation patterns during a printed word rhyme judgment task in 90 children with a wide range of reading abilities showed dissociation between brain regions that were sensitive to phonological awareness (left inferior frontal and inferior parietal regions) and rapid naming (right cerebellar lobule VI). More specifically, the double-deficit group showed less activation in the fronto-parietal reading network compared to children with only a deficit in phonological awareness, who in turn showed less activation than the typically-reading group. On the other hand, the double-deficit group showed less cerebellar activation compared to children with only a rapid naming deficit, who in turn showed less activation than the typically-reading children. Functional connectivity analyses revealed that bilateral prefrontal regions were key for linking brain regions associated with phonological awareness and rapid naming, with the double-deficit group being the most aberrant in their connectivity. Our study provides the first functional neuroanatomical evidence for the double-deficit hypothesis of developmental dyslexia. PMID:24953957

  12. Functional Neuroanatomical Evidence for the Double-Deficit Hypothesis of Developmental Dyslexia

    PubMed Central

    Norton, Elizabeth S.; Black, Jessica M.; Stanley, Leanne M.; Tanaka, Hiroko; Gabrieli, John D. E.; Sawyer, Carolyn; Hoeft, Fumiko

    2015-01-01

    The double-deficit hypothesis of dyslexia posits that both rapid naming and phonological impairments can cause reading difficulties, and that individuals who have both of these deficits show greater reading impairments compared to those with a single deficit. Despite extensive behavioral research, the brain basis of poor reading with a double-deficit has never been investigated. The goal of the study was to evaluate the double-deficit hypothesis using functional MRI. Activation patterns during a printed word rhyme judgment task in 90 children with a wide range of reading abilities showed dissociation between brain regions that were sensitive to phonological awareness (left inferior frontal and inferior parietal regions) and rapid naming (right cerebellar lobule VI). More specifically, the double-deficit group showed less activation in the fronto-parietal reading network compared to children with only a deficit in phonological awareness, who in turn showed less activation than the typically-reading group. On the other hand, the double-deficit group showed less cerebellar activation compared to children with only a rapid naming deficit, who in turn showed less activation than the typically-reading children. Functional connectivity analyses revealed that bilateral prefrontal regions were key for linking brain regions associated with phonological awareness and rapid naming, with the double-deficit group being the most aberrant in their connectivity. Our study provides the first functional neuroanatomical evidence for the double-deficit hypothesis of developmental dyslexia. PMID:24953957

  13. Intact action segmentation in Parkinson's disease: Hypothesis testing using a novel computational approach.

    PubMed

    Schiffer, Anne-Marike; Nevado-Holgado, Alejo J; Johnen, Andreas; Schönberger, Anna R; Fink, Gereon R; Schubotz, Ricarda I

    2015-11-01

    Action observation is known to trigger predictions of the ongoing course of action and thus considered a hallmark example for predictive perception. A related task, which explicitly taps into the ability to predict actions based on their internal representations, is action segmentation; the task requires participants to demarcate where one action step is completed and another one begins. It thus benefits from a temporally precise prediction of the current action. Formation and exploitation of these temporal predictions of external events is now closely associated with a network including the basal ganglia and prefrontal cortex. Because decline of dopaminergic innervation leads to impaired function of the basal ganglia and prefrontal cortex in Parkinson's disease (PD), we hypothesised that PD patients would show increased temporal variability in the action segmentation task, especially under medication withdrawal (hypothesis 1). Another crucial aspect of action segmentation is its reliance on a semantic representation of actions. There is no evidence to suggest that action representations are substantially altered, or cannot be accessed, in non-demented PD patients. We therefore expected action segmentation judgments to follow the same overall patterns in PD patients and healthy controls (hypothesis 2), resulting in comparable segmentation profiles. Both hypotheses were tested with a novel classification approach. We present evidence for both hypotheses in the present study: classifier performance was slightly decreased when it was tested for its ability to predict the identity of movies segmented by PD patients, and a measure of normativity of response behaviour was decreased when patients segmented movies under medication-withdrawal without access to an episodic memory of the sequence. This pattern of results is consistent with hypothesis 1. However, the classifier analysis also revealed that responses given by patients and controls create very similar action

  14. Visual Discriminatory Ability Among Prereaders.

    ERIC Educational Resources Information Center

    Blair, John Raymond; Ryckman, David B.

    The ability of 50 lower middle-class and 25 upper middle-class prereading children to discriminate between pairs of uppercase alphabet letters was tested. A set of 3x5 cards with a sample stimulus in the upper center section of each card and two alternative choice stimuli just below and to the right and left of the sample was used. The 650 total…

  15. A Comparison of the Proportional Reasoning Abilities of Learning Disabled and Non-Learning Disabled Children and Adolescents.

    ERIC Educational Resources Information Center

    Sinicrope, Rose; Mick, Lori Bell

    1983-01-01

    The study examined whether learning disabled students differed in development of proportional reasoning and whether their disability was in the use of symbols and language rather than ability to solve proportional problems. Developmental scalograms supported the hypothesis that LD Ss' proportional reasoning abilities are developmental, not unlike…

  16. Infants' ability to associate motion paths with object kinds.

    PubMed

    Baker, Rachel K; Pettigrew, Tamara L; Poulin-Dubois, Diane

    2014-02-01

    The goal of the present research was to examine whether infants associate different paths of motion with animate beings and inanimate objects. An infant-controlled habituation procedure was used to examine 10-20-month-old infants' ability to associate a non-linear motion path (jumping) with animals and a linear (rebounding) motion path with vehicles (Experiment 1) and furniture (Experiment 2). During the habituation phase, infants saw a dog jumping over a barrier and either a vehicle or a piece of furniture rebounding off the barrier. In the test phase, infants looked longer when another inanimate object jumped rather than rebounded, but showed no such differential looking in the case of another animate object. The ability to restrict the animate motion path of jumping to animate beings was present by 10 months of age. The present findings support the hypothesis that motion path is associated with the animate-inanimate distinction early in infancy. PMID:24486789

  17. Effects of non-differential exposure misclassification on false conclusions in hypothesis-generating studies.

    PubMed

    Burstyn, Igor; Yang, Yunwen; Schnatter, A Robert

    2014-01-01

    Despite the theoretical success of obviating the need for hypothesis-generating studies, they live on in epidemiological practice. Cole asserted that "… there is boundless number of hypotheses that could be generated, nearly all of them wrong" and urged us to focus on evaluating "credibility of hypothesis". Adopting a Bayesian approach, we put this elegant logic into quantitative terms at the study planning stage for studies where the prior belief in the null hypothesis is high (i.e., "hypothesis-generating" studies). We consider not only type I and II errors (as is customary) but also the probabilities of false positive and negative results, taking into account typical imperfections in the data. We concentrate on a common source of imperfection in the data: non-differential misclassification of binary exposure classifier. In context of an unmatched case-control study, we demonstrate-both theoretically and via simulations-that although non-differential exposure misclassification is expected to attenuate real effect estimates, leading to the loss of ability to detect true effects, there is also a concurrent increase in false positives. Unfortunately, most investigators interpret their findings from such work as being biased towards the null rather than considering that they are no less likely to be false signals. The likelihood of false positives dwarfed the false negative rate under a wide range of studied settings. We suggest that instead of investing energy into understanding credibility of dubious hypotheses, applied disciplines such as epidemiology, should instead focus attention on understanding consequences of pursuing specific hypotheses, while accounting for the probability that the observed "statistically significant" association may be qualitatively spurious. PMID:25337942

  18. [Rheumatic diseases and work ability].

    PubMed

    Minisola, Giovanni

    2014-01-01

    Musculoskeletal diseases are tile most frequent cause of pain in the working population. Rheumatic diseases are chronic illnesses, cause of functional impairnment, relevant working disability and absence from work; however, affected patients maintain a significant functional ability. In this context, the "Fit for work" project, operating in Italy since 2012, promotes the management of chronic musculoskeletal conditions through the realization, also in our country, of a rheumatic medical assistance network in behalf of workers affected by rheumatic diseases and other musculoskeletal disabiliting conditions. PMID:25558722

  19. An Experimental Analysis of Dynamic Hypotheses About Cognitive Abilities and Achievement From Childhood to Early Adulthood

    ERIC Educational Resources Information Center

    Ferrer, Emilio; McArdle, John J.

    2004-01-01

    This study examined the dynamics of cognitive abilities and academic achievement from childhood to early adulthood. Predictions about time-dependent "coupling" relations between cognition and achievement based on R. B. Cattell's (1971, 1987) investment hypothesis were evaluated using linear dynamic models applied to longitudinal data (N=672).…

  20. Development of Planning Abilities in Normal Aging: Differential Effects of Specific Cognitive Demands

    ERIC Educational Resources Information Center

    Köstering, Lena; Stahl, Christoph; Leonhart, Rainer; Weiller, Cornelius; Kaller, Christoph P.

    2014-01-01

    In line with the frontal hypothesis of aging, the ability to plan ahead undergoes substantial change during normal aging. Although impairments on the Tower of London planning task were reported earlier, associations between age-related declines and specific cognitive demands on planning have not been studied. Here we investigated the impact of…

  1. Specific Relations between Neurodevelopmental Abilities and White Matter Microstructure in Children Born Preterm

    ERIC Educational Resources Information Center

    Counsell, Serena J.; Edwards, A. David; Chew, Andrew T. M.; Anjari, Mustafa; Dyet, Leigh E.; Srinivasan, Latha; Boardman, James P.; Allsop, Joanna M.; Hajnal, Joseph V.; Rutherford, Mary A.; Cowan, Frances M.

    2008-01-01

    Survivors of preterm birth have a high incidence of neurodevelopmental impairment which is not explained by currently understood brain abnormalities. The aim of this study was to test the hypothesis that the neurodevelopmental abilities of 2-year-old children who were born preterm and who had no evidence of focal abnormality on conventional MR…

  2. Evidence of Shifting Standards in Judgments of Male and Female Parents' Job-Related Ability

    ERIC Educational Resources Information Center

    Fuegen, Kathleen; Endicott, Nicole F.

    2010-01-01

    We tested the hypothesis, derived from the shifting standards model of stereotyping, that parenthood would polarize judgments of men's and women's job-related ability. One hundred thirty-five attorneys evaluated the resume of a recent law school graduate. The resume depicted the graduate as male or female and as either single or married with two…

  3. A Lateralization of Function Approach to Sex Differences in Spatial Ability: A Reexamination

    ERIC Educational Resources Information Center

    Rilea, Stacy L.

    2008-01-01

    The current study assessed the lateralization of function hypothesis (Rilea, S. L., Roskos-Ewoldsen, B., & Boles, D. (2004). "Sex differences in spatial ability: A lateralization of function approach." "Brain and Cognition," 56, 332-343) which suggested that it was the interaction of brain organization and the type of spatial task that led to sex…

  4. Spatial Abilities in an Elective Course of Applied Anatomy after a Problem-Based Learning Curriculum

    ERIC Educational Resources Information Center

    Langlois, Jean; Wells, George A.; Lecourtois, Marc; Bergeron, Germain; Yetisir, Elizabeth; Martin, Marcel

    2009-01-01

    A concern on the level of anatomy knowledge reached after a problem-based learning curriculum has been documented in the literature. Spatial anatomy, arguably the highest level in anatomy knowledge, has been related to spatial abilities. Our first objective was to test the hypothesis that residents are interested in a course of applied anatomy…

  5. Individual Differences in Gender Role Beliefs Influence Spatial Ability Test Performance

    ERIC Educational Resources Information Center

    Massa, Laura J.; Mayer, Richard E.; Bohon, Lisa M.

    2005-01-01

    The gender role hypothesis posits that performance on a cognitive ability test is influenced by whether the test instructions frame the test as measuring a skill that is consistent or inconsistent with the test taker's gender role beliefs. The Bem sex role inventory was used to measure the gender role of female college students, and the group…

  6. Neural correlates of cognitive ability.

    PubMed

    Brancucci, Alfredo

    2012-07-01

    The challenge to neuroscientists working on intelligence is to discover what neural structures and mechanisms are at the basis of such a complex and variegated capability. Several psychologists agree on the view that behavioral flexibility is a good measure of intelligence, resulting in the appearance of novel solutions that are not part of the animal's normal behavior. This article tries to indicate how the supposed differences in intelligence between species can be related to brain properties and suggests that the best neural indicators may be the ones that convey more information processing capacity to the brain, i.e., high conduction velocity of fibers and small distances between neurons, associated with a high number of neurons and an adequate level of connectivity. The neural bases of human intelligence have been investigated by means of anatomical, neurophysiological, and neuropsychological methods. These investigations have led to two important findings that are briefly discussed: the parietofrontal integration theory of intelligence, which assumes that a distributed network of cortical areas having its main nodes in the frontal and parietal lobes constitutes a probable substrate for smart behavior, and the neural efficiency hypothesis, according to which intelligent people process information more efficiently, showing weaker neural activations in a smaller number of areas than less intelligent people. PMID:22422612

  7. Negative compatibility effect: the object-updating hypothesis revisited.

    PubMed

    Jaśkowski, Piotr

    2009-02-01

    A prime even if backward masked can affect the reaction to a subsequently presented target. According to the object-updating hypothesis, negative CE (i.e. longer reactions in the compatible than incompatible trials) occurs due to the interaction between prime and a subsequent stimulus (usually a mask or flanker). Its crucial assumption is that only new elements of the mask can affect the response. As the masks are usually composed of figures that call for both possible responses, the masks' new element calls for a response opposite to that initialized by the prime. Here an experiment is described in which the prime and target were two arrowheads pointing to left or right. Two different flankers were composed from the two heads pointing to the opposite directions. In contrast to the OU hypothesis, NCEs were different for the two flankers. This finding contradicts the OU hypothesis. PMID:19156401

  8. RPD-based Hypothesis Reasoning for Cyber Situation Awareness

    NASA Astrophysics Data System (ADS)

    Yen, John; McNeese, Michael; Mullen, Tracy; Hall, David; Fan, Xiaocong; Liu, Peng

    Intelligence workers such as analysts, commanders, and soldiers often need a hypothesis reasoning framework to gain improved situation awareness of the highly dynamic cyber space. The development of such a framework requires the integration of interdisciplinary techniques, including supports for distributed cognition (human-in-the-loop hypothesis generation), supports for team collaboration (identification of information for hypothesis evaluation), and supports for resource-constrained information collection (hypotheses competing for information collection resources). We here describe a cognitively-inspired framework that is built upon Klein’s recognition-primed decision model and integrates the three components of Endsley’s situation awareness model. The framework naturally connects the logic world of tools for cyber situation awareness with the mental world of human analysts, enabling the perception, comprehension, and prediction of cyber situations for better prevention, survival, and response to cyber attacks by adapting missions at the operational, tactical, and strategic levels.

  9. Deep and beautiful. The reward prediction error hypothesis of dopamine.

    PubMed

    Colombo, Matteo

    2014-03-01

    According to the reward-prediction error hypothesis (RPEH) of dopamine, the phasic activity of dopaminergic neurons in the midbrain signals a discrepancy between the predicted and currently experienced reward of a particular event. It can be claimed that this hypothesis is deep, elegant and beautiful, representing one of the largest successes of computational neuroscience. This paper examines this claim, making two contributions to existing literature. First, it draws a comprehensive historical account of the main steps that led to the formulation and subsequent success of the RPEH. Second, in light of this historical account, it explains in which sense the RPEH is explanatory and under which conditions it can be justifiably deemed deeper than the incentive salience hypothesis of dopamine, which is arguably the most prominent contemporary alternative to the RPEH. PMID:24252364

  10. On Using Taylor's Hypothesis for Three-Dimensional Mixing Layers

    NASA Technical Reports Server (NTRS)

    LeBoeuf, Richard L.; Mehta, Rabindra D.

    1995-01-01

    In the present study, errors in using Taylor's hypothesis to transform measurements obtained in a temporal (or phase) frame onto a spatial one were evaluated. For the first time, phase-averaged ('real') spanwise and streamwise vorticity data measured on a three-dimensional grid were compared directly to those obtained using Taylor's hypothesis. The results show that even the qualitative features of the spanwise and streamwise vorticity distributions given by the two techniques can be very different. This is particularly true in the region of the spanwise roller pairing. The phase-averaged spanwise and streamwise peak vorticity levels given by Taylor's hypothesis are typically lower (by up to 40%) compared to the real measurements.

  11. Local equilibrium hypothesis and Taylor’s dissipation law

    NASA Astrophysics Data System (ADS)

    Goto, Susumu; Vassilicos, J. C.

    2016-04-01

    To qualitatively investigate the validity of Kolmogorov local equilibrium hypothesis and the Taylor dissipation law, we conduct direct numerical simulations of the three-dimensional turbulent Kolmogorov flow. Since strong scale-by-scale (i.e. Richardson-type) energy cascade events occur quasi-periodically, the kinetic energy of the turbulence and its dissipation rate evolve quasi-periodically too. In this unsteady turbulence driven by a steady force, instantaneous values of the dissipation rate obey the scaling recently discovered in wind tunnel experiments (Vassilicos 2015 Ann. Rev. Fluid Mech. 47 95-114) instead of the Taylor dissipation law. The Taylor dissipation law does not hold because the local equilibrium hypothesis does not hold in a relatively low wave-number range. The breakdown of this hypothesis is caused by the finite time needed for the energy at such large scales to reach the dissipative scale by the scale-by-scale energy cascade.

  12. The evolution of Trypanosoma cruzi: the 'bat seeding' hypothesis.

    PubMed

    Hamilton, Patrick B; Teixeira, Marta M G; Stevens, Jamie R

    2012-04-01

    Recent discussions on the evolution of Trypanosoma cruzi have been dominated by the southern super-continent hypothesis, whereby T. cruzi and related parasites evolved in isolation in the mammals of South America, Antarctica and Australia. Here, we consider recent molecular evidence suggesting that T. cruzi evolved from within a broader clade of bat trypanosomes, and that bat trypanosomes have successfully made the switch into other mammalian hosts in both the New and Old Worlds. Accordingly, we propose an alternative hypothesis--the bat seeding hypothesis--whereby lineages of bat trypanosomes have switched into terrestrial mammals, thereby seeding the terrestrial lineages within the clade. One key implication of this finding is that T. cruzi may have evolved considerably more recently than previously envisaged. PMID:22365905

  13. Extraversion and the EEG: II. A test of Gale's hypothesis.

    PubMed

    O'Gorman, J G; Mallise, L R

    1984-09-01

    The study sought to test A. Gale's hypothesis that only under moderately arousing conditions will introverts be shown to differ from extraverts in EEG defined arousal. Alpha activity was recorded for 45 subjects under each of six conditions, and extravert and introvert groups formed on the basis of subject's score on the E scale of the Eysenck Personality Questionnaire (EPQ). Contrary to the hypothesis, extraverts showed more prestimulus alpha activity than introverts under all conditions except opening and closing eyes on instruction where the reverse was the case. It is argued that the failure to confirm the hypothesis is not due to faults in design or execution of the study, and that future research may profit more from ignoring interactions of the sort demonstrated. PMID:6518221

  14. Unicorns do exist: a tutorial on "proving" the null hypothesis.

    PubMed

    Streiner, David L

    2003-12-01

    Introductory statistics classes teach us that we can never prove the null hypothesis; all we can do is reject or fail to reject it. However, there are times when it is necessary to try to prove the nonexistence of a difference between groups. This most often happens within the context of comparing a new treatment against an established one and showing that the new intervention is not inferior to the standard. This article first outlines the logic of "noninferiority" testing by differentiating between the null hypothesis (that which we are trying to nullify) and the "nill" hypothesis (there is no difference), reversing the role of the null and alternate hypotheses, and defining an interval within which groups are said to be equivalent. We then work through an example and show how to calculate sample sizes for noninferiority studies. PMID:14733457

  15. Multiple fault condition recognition of gearbox with sequential hypothesis test

    NASA Astrophysics Data System (ADS)

    Chen, Hanxin; Shang, Yunfei; Sun, Kui

    2013-11-01

    A novel method for the fault condition recognition in which the recognition system interrogates a propagation channel adaptively and intelligently by using the available data is proposed based on sequential hypothesis testing. The waveform of the data in the propagation channel for the fault condition recognition is designed with the kurtosis of the measured data in time domain. The sequential hypothesis testing framework is proposed when hard decisions are made with adequate confidence. The distinguished characteristic of the channel recognition is that it operates in a closed loop and makes constant optimization in response to its changing understanding of the channel. The fault condition recognition of the gearbox is to update the multiple target hypothesis/class based on the measured data, customize waveform as the class probabilities changes, and make conclusion when the sufficient understanding of the propagation channel is achieved.

  16. Low intelligence and special abilities.

    PubMed

    O'Connor, N; Hermelin, B

    1988-07-01

    In summary, our research enables us to conclude that specific talents are found in people who differ widely in general intelligence levels and such talents should therefore be regarded as at least partly intelligence-independent. However, between normal and mentally handicapped populations and even within the idiot savant group, general cognitive capacity plays some part in determining the manner in which talents manifest themselves. Idiot savant special abilities can neither be regarded as the sole consequence of practice and training, nor are such skills based only on an efficient rote memory. Instead, idiots savants use strategies which are founded on the deduction and application of rules governing the material upon which their special ability operates. They also generate novel or new examples of such rule based structures just as we do in our use of language. Because of the much greater prevalence of idiots savants in the autistic than in the mentally handicapped population, some characteristic common to both autism and specific giftedness might be assumed. An obsessional pre-occupation with a limited section of the environment might be a common factor to both. It may be this rather than autism itself which is relevant to the idiot savant phenomenon. PMID:3063716

  17. Recent sediment studies refute Glen Canyon Dam hypothesis

    USGS Publications Warehouse

    Rubin, David M.; Topping, David J.; Schmidt, John C.; Hazel, Joe; Kaplinski, Matt; Melis, Theodore S.

    2002-01-01

    Recent studies of sedimentology hydrology, and geomorphology indicate that releases from Glen Canyon Dam are continuing to erode sandbars and beaches in the Colorado River in Grand Canyon National Park, despite attempts to restore these resources. The current strategy for dam operations is based on the hypothesis that sand supplied by tributaries of the Colorado River downstream from the dam will accumulate in the channel during normal dam operations and remain available for restoration floods. Recent work has shown that this hypothesis is false, and that tributary sand inputs are exported downstream rapidly typically within weeks or months under the current flow regime.

  18. Tunguska, 1908: the gas pouch and soil fluidization hypothesis

    NASA Astrophysics Data System (ADS)

    Nistor, I.

    2012-01-01

    The Siberian taiga explosion of 30 June 1908 remains one of the great mysteries of the 20th century: millions of trees put down over an area of 2200 km2 without trace of a crater or meteorite fragments. Hundred years of failed searches have followed, resulting in as many flawed hypothesis which could not offer satisfactory explanations: meteorite, comet, UFO, etc. In the author's opinion, the cause is that the energy the explorers looked for was simply not there! The author's hypothesis is that a meteoroid encountered a gas pouch in the atmosphere, producing a devastating explosion, its effects being amplified by soil fluidization.

  19. A lattice gas of prime numbers and the Riemann Hypothesis

    NASA Astrophysics Data System (ADS)

    Vericat, Fernando

    2013-10-01

    In recent years, there has been some interest in applying ideas and methods taken from Physics in order to approach several challenging mathematical problems, particularly the Riemann Hypothesis. Most of these kinds of contributions are suggested by some quantum statistical physics problems or by questions originated in chaos theory. In this article, we show that the real part of the non-trivial zeros of the Riemann zeta function extremizes the grand potential corresponding to a simple model of one-dimensional classical lattice gas, the critical point being located at 1/2 as the Riemann Hypothesis claims.

  20. Paleomagnetic test of the Emperor fracture zone hypothesis

    SciTech Connect

    Gordon, R.G.

    1982-11-01

    Late Cretaceous paleomagnetic data from the Pacific plate were used to test Farrar and Dixon's (1981) hypothesis that approx.1700 km of strike-slip accumulated during the early Tertiary along the Emperor fracture zone system, and 8000 km long NW-SE trending features, which consists mainly of the Emperor trough, the Gardner seamounts, and the Line Islands. The data strongly disagree with this hypothesis; instead the data are consistent with no motion having occurred between seafloor east of the Emperor fracture zone and seafloor west of the Emperor fracture zone.

  1. Formal reasoning ability and misconceptions concerning genetics and natural selection

    NASA Astrophysics Data System (ADS)

    Lawson, Anton E.; Thompson, Lois D.

    Students often hold misconceptions about natural phenomena. To overcome misconceptions students must become aware of the scientific conceptions, the evidence that bears on the validity of their misconceptions and the scientific conceptions, and they must be able to generate the logical relationships among the evidence and alternative conceptions. Because formal operational reasoning patterns are necessary to generate these logical relationships, it was predicted that, following instruction, formal operational students would hold significantly fewer misconceptions than their concrete operational classmates. To test this hypothesis 131 seventh-grade students were administered an essay test on principles of genetics and natural selection following instruction. Responses were categorized in terms of the number of misconceptions present. The number of misconceptions was compared to reasoning ability (concrete, transitional, formal), mental capacity (<6, 6, 7), verbal intelligence (low, medium, high), and cognitive style (field dependent, intermediate, field independent). The only student variable consistently and significantly related to the number of misconceptions was reasoning ability; thus, support for the major hypothesis of the study was obtained.

  2. Brain size predicts problem-solving ability in mammalian carnivores.

    PubMed

    Benson-Amram, Sarah; Dantzer, Ben; Stricker, Gregory; Swanson, Eli M; Holekamp, Kay E

    2016-03-01

    Despite considerable interest in the forces shaping the relationship between brain size and cognitive abilities, it remains controversial whether larger-brained animals are, indeed, better problem-solvers. Recently, several comparative studies have revealed correlations between brain size and traits thought to require advanced cognitive abilities, such as innovation, behavioral flexibility, invasion success, and self-control. However, the general assumption that animals with larger brains have superior cognitive abilities has been heavily criticized, primarily because of the lack of experimental support for it. Here, we designed an experiment to inquire whether specific neuroanatomical or socioecological measures predict success at solving a novel technical problem among species in the mammalian order Carnivora. We presented puzzle boxes, baited with food and scaled to accommodate body size, to members of 39 carnivore species from nine families housed in multiple North American zoos. We found that species with larger brains relative to their body mass were more successful at opening the boxes. In a subset of species, we also used virtual brain endocasts to measure volumes of four gross brain regions and show that some of these regions improve model prediction of success at opening the boxes when included with total brain size and body mass. Socioecological variables, including measures of social complexity and manual dexterity, failed to predict success at opening the boxes. Our results, thus, fail to support the social brain hypothesis but provide important empirical support for the relationship between relative brain size and the ability to solve this novel technical problem. PMID:26811470

  3. Generalist genes and cognitive abilities in Chinese twins.

    PubMed

    Chow, Bonnie Wing-Yin; Ho, Connie Suk-Han; Wong, Simpson Wai-Lap; Waye, Mary M Y; Bishop, Dorothy V M

    2013-03-01

    This study considered how far nonverbal cognitive, language and reading abilities are affected by common genetic influences in a sample of 312 typically developing Chinese twin pairs aged from 3 to 11 years. Children were individually given tasks of Chinese word reading, receptive vocabulary, phonological memory, tone awareness, syllable and rhyme awareness, rapid automatized naming, morphological awareness and orthographic skills, and Raven's Colored Progressive Matrices. Factor analyses on the verbal tasks adjusted for age indicated two factors: Language as the first factor and Reading as the second factor. Univariate genetic analyses indicated that genetic influences were substantial for nonverbal cognitive ability and moderate for language and reading. Multivariate genetic analyses showed that nonverbal cognitive ability, language and reading were influenced by shared genetic origins, although there were specific genetic influences on verbal skills that were distinct from those on nonverbal cognitive ability. This study extends the Generalist Genes Hypothesis to Chinese language and reading skills, suggesting that the general effects of genes could be universal across languages. PMID:23432835

  4. Brain size predicts problem-solving ability in mammalian carnivores

    PubMed Central

    Benson-Amram, Sarah; Dantzer, Ben; Stricker, Gregory; Swanson, Eli M.; Holekamp, Kay E.

    2016-01-01

    Despite considerable interest in the forces shaping the relationship between brain size and cognitive abilities, it remains controversial whether larger-brained animals are, indeed, better problem-solvers. Recently, several comparative studies have revealed correlations between brain size and traits thought to require advanced cognitive abilities, such as innovation, behavioral flexibility, invasion success, and self-control. However, the general assumption that animals with larger brains have superior cognitive abilities has been heavily criticized, primarily because of the lack of experimental support for it. Here, we designed an experiment to inquire whether specific neuroanatomical or socioecological measures predict success at solving a novel technical problem among species in the mammalian order Carnivora. We presented puzzle boxes, baited with food and scaled to accommodate body size, to members of 39 carnivore species from nine families housed in multiple North American zoos. We found that species with larger brains relative to their body mass were more successful at opening the boxes. In a subset of species, we also used virtual brain endocasts to measure volumes of four gross brain regions and show that some of these regions improve model prediction of success at opening the boxes when included with total brain size and body mass. Socioecological variables, including measures of social complexity and manual dexterity, failed to predict success at opening the boxes. Our results, thus, fail to support the social brain hypothesis but provide important empirical support for the relationship between relative brain size and the ability to solve this novel technical problem. PMID:26811470

  5. The Effectiveness of the Comprehension Hypothesis: A Review on the Current Research on Incidental Vocabulary Acquisition

    ERIC Educational Resources Information Center

    Ponniah, Joseph

    2011-01-01

    The Comprehension Hypothesis (CH) is the most powerful hypothesis in the field of Second Language Acquisition despite the presence of the rivals the skill-building hypothesis, the output hypothesis, and the interaction hypothesis. The competing hypotheses state that consciously learned linguistic knowledge is a necessary step for the development…

  6. The Aspect Hypothesis: Development of Morphology and Appropriateness of Use

    ERIC Educational Resources Information Center

    Comajoan, Llorenc

    2006-01-01

    According to the aspect hypothesis (Andersen & Shirai, 1996; Bardovi-Harlig, 2000), perfective morphology emerges before imperfective morphology, it is first used in telic predicates (achievements and accomplishments) and it later extends to atelic predicates (activities and states). The opposite development is hypothesized for imperfective…

  7. Four Centuries of the Geocentric Axial Dipole Hypothesis

    NASA Astrophysics Data System (ADS)

    Tauxe, L.; Kent, D. V.

    2004-12-01

    William Gilbert first articulated what has come to be known as the geocentric axial dipole hypothesis. The GAD hypothesis is the principle on which paleogeographic reconstructions rely to constrain paleolatitude. For decades there have been calls for permanent non-dipole contributions to the time averaged field. Recently, these have demanded large contributions of the axial octupole, which, if valid, would call into question the general utility of the GAD hypothesis. In the process of geological recording of the geomagnetic field, ``Earth filters'' distort the directions. Many processes, for example, sedimentary inclination error and random tilting lead to a net shallowing of the observed direction. Therefore inclinations that are shallower than expected from GAD can be explained by recording biases, northward transport, or non-dipole geomagnetic fields. Using paleomagnetic data from the last five million years from well constrained lava flow data allows the construction of a statistical geomagnetic field model. Such a model can predict not only the average expected direction for a given latitude, but also the shape of the distribution of directions produced by secular variation. This allows us to differentiate among the possible explanations for shallow bias. We find no compelling reason to abandon the geocentric dipole hypothesis that has served us well for four centuries.

  8. Testosterone and oxidative stress: the oxidation handicap hypothesis

    PubMed Central

    Alonso-Alvarez, Carlos; Bertrand, Sophie; Faivre, Bruno; Chastel, Olivier; Sorci, Gabriele

    2006-01-01

    Secondary sexual traits (SST) are usually thought to have evolved as honest signals of individual quality during mate choice. Honesty of SST is guaranteed by the cost of producing/maintaining them. In males, the expression of many SST is testosterone-dependent. The immunocompetence handicap hypothesis has been proposed as a possible mechanism ensuring honesty of SST on the basis that testosterone, in addition to its effect on sexual signals, also has an immunosuppressive effect. The immunocompetence handicap hypothesis has received mixed support. However, the cost of testosterone-based signalling is not limited to immunosuppression and might involve other physiological functions such as the antioxidant machinery. Here, we tested the hypothesis that testosterone depresses resistance to oxidative stress in a species with a testosterone-dependent sexual signal, the zebra finch. Male zebra finches received subcutaneous implants filled with flutamide (an anti-androgen) or testosterone, or kept empty (control). In agreement with the prediction, we found that red blood cell resistance to a free radical attack was the highest in males implanted with flutamide and the lowest in males implanted with testosterone. We also found that cell-mediated immune response was depressed in testosterone-treated birds, supporting the immunocompetence handicap hypothesis. The recent finding that red blood cell resistance to free radicals is negatively associated with mortality in this species suggests that benefits of sexual signalling might trade against the costs derived from oxidation. PMID:17251089

  9. The neurodevelopmental hypothesis of schizophrenia: a review of recent developments.

    PubMed

    McGrath, John J; Féron, François P; Burne, Thomas H J; Mackay-Sim, Alan; Eyles, Darryl W

    2003-01-01

    The neurodevelopmental hypothesis (NDH) of schizophrenia suggests that a disruption of brain development during early life underlies the later emergence of psychosis during adulthood. The aim of this review is to chart the challenges and subsequent refinements to this hypothesis, with particular reference to the static versus progressive nature of the putative neurobiological processes underlying the NDH. A non-systematic literature review was undertaken, with an emphasis on major review papers relevant to the NDH. Weaknesses in the explanatory power of the NDH have led to a new generation of more refined hypotheses in recent years. In particular, recent versions of the hypothesis have incorporated evidence from structural neuroimaging which suggests changes in brain volumes after the onset of schizophrenia. More detailed models that incorporate progressive neurobiological processes have replaced early versions of the NDH, which were based on a 'static encephalopathy'. In addition, recent models have suggested that two or more 'hits' are required over the lifespan rather than only one early-life event. Animal models are providing important insights into the sequelae of disturbed early brain development. The NDH has provided great impetus to the schizophrenia research community. Recent versions of the hypothesis have encouraged more focused and testable hypotheses. PMID:12795338

  10. The "Discouraged-Business-Major" Hypothesis: Policy Implications

    ERIC Educational Resources Information Center

    Marangos, John

    2012-01-01

    This paper uses a relatively large dataset of the stated academic major preferences of economics majors at a relatively large, not highly selective, public university in the USA to identify the "discouraged-business-majors" (DBMs). The DBM hypothesis addresses the phenomenon where students who are screened out of the business curriculum often…

  11. Acquisition in Context: The Discourse Domain Hypothesis of Interlanguage Variation.

    ERIC Educational Resources Information Center

    Whyte, Shona

    This study tested a refined version of the discourse domain hypothesis, which defines the discourse domain as a topic area in which second language learners demonstrate extensive, current, and important knowledge, including both cognitive and affective dimensions. The study tested the results of previous studies, which showed that learners show…

  12. Bimodal Bilingualism and the Frequency-Lag Hypothesis

    ERIC Educational Resources Information Center

    Emmorey, Karen; Petrich, Jennifer A. F.; Gollan, Tamar H.

    2013-01-01

    The frequency-lag hypothesis proposes that bilinguals have slowed lexical retrieval relative to monolinguals and in their nondominant language relative to their dominant language, particularly for low-frequency words. These effects arise because bilinguals divide their language use between 2 languages and use their nondominant language less…

  13. Bayesian Approaches to Imputation, Hypothesis Testing, and Parameter Estimation

    ERIC Educational Resources Information Center

    Ross, Steven J.; Mackey, Beth

    2015-01-01

    This chapter introduces three applications of Bayesian inference to common and novel issues in second language research. After a review of the critiques of conventional hypothesis testing, our focus centers on ways Bayesian inference can be used for dealing with missing data, for testing theory-driven substantive hypotheses without a default null…

  14. Planned Hypothesis Tests Are Not Necessarily Exempt from Multiplicity Adjustment

    ERIC Educational Resources Information Center

    Frane, Andrew V.

    2015-01-01

    Scientific research often involves testing more than one hypothesis at a time, which can inflate the probability that a Type I error (false discovery) will occur. To prevent this Type I error inflation, adjustments can be made to the testing procedure that compensate for the number of tests. Yet many researchers believe that such adjustments are…

  15. On the Hypothesis of Control of the Universe

    NASA Astrophysics Data System (ADS)

    Kalanov, Temur Z.

    2007-04-01

    The problem of the SETI is not solved till now because idea of the SETI represents a methodological error in cosmology and astrophysics. This fact means that one should prove existence of Supreme Intelligence in a correct way. In this connection, the hypothesis of control of the Universe is proposed. The hypothesis is based on the new point of view [1] according to which information is essence of the Universe, and material objects are manifestation of the essence. The hypothesis is formulated as follows: (1) the Universe represents the cybernetic system; (2) the cybernetic system is a set of mutual connected elements which receive, memorize, process, and transmit information; (3) each material element (for example, atom, molecule, man, the Earth, the Sun) is a unity of opposites: the controlling aspect and the controllable aspect; (4) the Universe as a system is a unity of opposites: the controlling aspect and the controllable aspect. Consequently, the Universe is controlled by the certain object. Thus, the problem of definition of the controlling object arises. Correct solution of this problem is the key to exploration of the Universe. Ref.: [1] T.Z. Kalanov, ``On the hypothesis of Universe's ``system block'' ''. Bulletin of the APS, Vol. 51, No. 2 (2006), p. 61.

  16. Interpersonal Attraction in Relation to the Loss-Gain Hypothesis.

    ERIC Educational Resources Information Center

    Sharma, Vandana; Kaur, Inderjeet

    1996-01-01

    Maintains that a loss-gain hypothesis (a negative impression gives way to a positive one) is a more powerful indicator and incentive for future friendship than an opposite sequence (positive to negative). Both of these, however, were eclipsed by a positive-positive interaction as a determinant of interpersonal attraction. (MJP)

  17. Hypothesis, Prediction, and Conclusion: Using Nature of Science Terminology Correctly

    ERIC Educational Resources Information Center

    Eastwell, Peter

    2012-01-01

    This paper defines the terms "hypothesis," "prediction," and "conclusion" and shows how to use the terms correctly in scientific investigations in both the school and science education research contexts. The scientific method, or hypothetico-deductive (HD) approach, is described and it is argued that an understanding of the scientific method,…

  18. RAN Backward: A Test of the Visual Scanning Hypothesis

    ERIC Educational Resources Information Center

    Protopapas, Athanassios; Altani, Angeliki; Georgiou, George K.

    2013-01-01

    Rapid automatized naming (RAN) is strongly correlated with reading fluency. A substantial part of this correlation is ascribed to the serial nature of the task. In this study, we tested the hypothesis that the left-to-right and downward scanning direction of reading and RAN may partially underlie their relationship. 107 Grade 6 Greek children were…

  19. Milk kinship hypothesis in light of epigenetic knowledge

    PubMed Central

    2012-01-01

    Background A wet nurse can be used if a baby’s natural mother is unable or chooses not to breastfeed her infant. The practice of using wet nurses is ancient and common to many cultures. Presentation of the hypothesis We hypothesize that infants breastfeeding from the same woman may develop consanguinity even in cases in which they are not blood relatives, and that children of two individuals breastfed by the same woman may thus be at risk of several genetic diseases because of such consanguinity. Testing the hypothesis Possible evidence for the milk kinship hypothesis is to be found in the composition of breast milk, which is composed of living substances such as stem cells or substances that can affect epigenetic regulation such as microRNAs. Implications of the hypothesis If these epigenetic modifications are heritable, marriages between individuals breastfed by the same woman may result in the same consequences as consanguineous marriages. In this paper, we attempt to assess this possibility. PMID:22989202

  20. Stereotype Measurement and the "Kernel of Truth" Hypothesis.

    ERIC Educational Resources Information Center

    Gordon, Randall A.

    1989-01-01

    Describes a stereotype measurement suitable for classroom demonstration. Illustrates C. McCauley and C. L. Stitt's diagnostic ratio measure and examines the validity of the "kernel of truth" hypothesis. Uses this as a starting point for class discussion. Reports results and gives suggestions for discussion of related concepts. (Author/NL)

  1. The Declarative/Procedural Model and the Shallow Structure Hypothesis

    ERIC Educational Resources Information Center

    Ullman, Michael T.

    2006-01-01

    Clahsen and Felser (CF) have written a beautiful and important paper. I applaud their integrative empirical approach, and believe that their theoretical account is largely correct, if not in some of its specific claims, at least in its broader assumptions. CF directly compare their shallow structure hypothesis (SSH) with a model that my colleagues…

  2. A Life-Course Perspective on the "Gateway Hypothesis"

    ERIC Educational Resources Information Center

    Van Gundy, Karen; Rebellon, Cesar J.

    2010-01-01

    Drawing on stress and life-course perspectives and using panel data from 1,286 south Florida young adults, we assess three critical questions regarding the role of marijuana in the "gateway hypothesis." First, does teen marijuana use independently (causally) affect subsequent use of more dangerous substances? Second, if so, does that effect apply…

  3. A Double-Deficit Hypothesis for Developmental Reading Disorders.

    ERIC Educational Resources Information Center

    Bowers, Patricia Greig; Wolff, Maryanne

    Two longitudinal studies examined a "double deficit" hypothesis of reading disorders that contends that along with a core phonological deficit, slow speed of lexical access disrupts the efficient formation of orthographic representations and their quick retrieval. In the first study, 38 children from 6 classrooms in a predominantly white, middle…

  4. Evaluation of an Interactive Tutorial for Teaching Hypothesis Testing Concepts

    ERIC Educational Resources Information Center

    Aberson, Christopher L.; Berger, Dale E.; Healy, Michael R.; Romero, Victoria L.

    2003-01-01

    In this article, we describe and evaluate a Web-based interactive tutorial used to present hypothesis testing concepts. The tutorial includes multiple-choice questions with feedback, an interactive applet that allows students to draw samples and evaluate null hypotheses, and follow-up questions suitable for grading. Students either used the…

  5. The Evolving Context of the Fundamental Difference Hypothesis

    ERIC Educational Resources Information Center

    Bley-Vroman, Robert

    2009-01-01

    Foreign language learning contrasts with native language development in two key respects: It is unreliable and it is nonconvergent. At the same time, it is clear that foreign languages are languages. The fundamental difference hypothesis (FDH) was introduced as a way to account for the general characteristics of foreign language learning. The FDH…

  6. Examination of the Eyberg Child Behavior Inventory Discrepancy Hypothesis

    ERIC Educational Resources Information Center

    Butler, Ashley M.; Brestan, Elizabeth V.; Eyberg, Sheila M.

    2008-01-01

    This study examined the Eyberg Child Behavior Inventory (ECBI) "discrepancy hypothesis", which asserts that a discrepancy in score elevations on the ECBI Intensity and Problem Scales is related to problematic parenting styles. The Intensity Scale measures the frequency of child disruptive behavior, and the Problem Scale measures parent perception…

  7. BENZODIAZEPINES FOR PROMINENT AUDITORY HALLUCINATIONS: A REPORT AND HYPOTHESIS

    PubMed Central

    Andrade, Chittaranjan

    1995-01-01

    A case is reported of diazepam - induced amelioration of prominent auditory hallucinations experienced by a female paranoid schizophrenic. With the assumption that subvocal speech may be primary to such hallucinations, it is proposed that diazepam may have acted by exerting a relaxant effect on speech musculature. This is a hypothesis testable in future research. PMID:21743715

  8. Learner Output, Hypothesis Testing, and Internalizing Linguistic Knowledge.

    ERIC Educational Resources Information Center

    Shehadeh, Ali

    2003-01-01

    Investigates how output can be a process by which second language (L2) learners test out hypotheses about the L2 and the extent to which learner hypothesis testing attempts that result in non-target like (NTL) output are challenged by interlocutors. A picture-descriptions task was used to collect data from eight native- and eight…

  9. Testosterone and oxidative stress: the oxidation handicap hypothesis.

    PubMed

    Alonso-Alvarez, Carlos; Bertrand, Sophie; Faivre, Bruno; Chastel, Olivier; Sorci, Gabriele

    2007-03-22

    Secondary sexual traits (SST) are usually thought to have evolved as honest signals of individual quality during mate choice. Honesty of SST is guaranteed by the cost of producing/maintaining them. In males, the expression of many SST is testosterone-dependent. The immunocompetence handicap hypothesis has been proposed as a possible mechanism ensuring honesty of SST on the basis that testosterone, in addition to its effect on sexual signals, also has an immunosuppressive effect. The immunocompetence handicap hypothesis has received mixed support. However, the cost of testosterone-based signalling is not limited to immunosuppression and might involve other physiological functions such as the antioxidant machinery. Here, we tested the hypothesis that testosterone depresses resistance to oxidative stress in a species with a testosterone-dependent sexual signal, the zebra finch. Male zebra finches received subcutaneous implants filled with flutamide (an anti-androgen) or testosterone, or kept empty (control). In agreement with the prediction, we found that red blood cell resistance to a free radical attack was the highest in males implanted with flutamide and the lowest in males implanted with testosterone. We also found that cell-mediated immune response was depressed in testosterone-treated birds, supporting the immunocompetence handicap hypothesis. The recent finding that red blood cell resistance to free radicals is negatively associated with mortality in this species suggests that benefits of sexual signalling might trade against the costs derived from oxidation. PMID:17251089

  10. The Antieconomy Hypothesis (Part 3): Toward a Solution

    ERIC Educational Resources Information Center

    Vanderburg, Willem H.

    2009-01-01

    Parts 1 and 2 explore the hypothesis that the application of mainstream economics has led to economies becoming uneconomic, which is as close as a social science can get to experimentally disproving its theories. One of the primary reasons for this failure is traced to the characteristics of the knowledge infrastructures of contemporary societies,…

  11. Samara Dispersal in Boxelder: An Exercise in Hypothesis Testing.

    ERIC Educational Resources Information Center

    Minorsky, Peter V.; Willing, R. Paul

    1999-01-01

    Presents a fun, inexpensive, and pedagogically useful laboratory exercise that involves indoor studies of the dispersal properties of the winged fruits (samaras) of boxelder trees. Engages students in the process of hypothesis testing, experimental design, and data analysis as well as introducing students to important concepts related to…

  12. A Local Contingency Analysis of the Fine-Tuning Hypothesis.

    ERIC Educational Resources Information Center

    Sokolov, Jeffrey L.

    1993-01-01

    Tested the fine-tuning hypothesis of language acquisition, which postulates that parents fine-tune their speech to their children's language level, by examining local patterns of interaction within the conversations of three parent-child dyads. The high positive correlations between parent-child dyads for the different interactional patterns…

  13. The catecholaminergic-cholinergic balance hypothesis of bipolar disorder revisited

    PubMed Central

    van Enkhuizen, Jordy; Janowsky, David S; Olivier, Berend; Minassian, Arpi; Perry, William; Young, Jared W; Geyer, Mark A

    2014-01-01

    Bipolar disorder is a unique illness characterized by fluctuations between mood states of depression and mania. Originally, an adrenergic-cholinergic balance hypothesis was postulated to underlie these different affective states. In this review, we update this hypothesis with recent findings from human and animal studies, suggesting that a catecholaminergic-cholinergic hypothesis may be more relevant. Evidence from neuroimaging studies, neuropharmacological interventions, and genetic associations support the notion that increased cholinergic functioning underlies depression, whereas increased activations of the catecholamines (dopamine and norepinephrine) underlie mania. Elevated functional acetylcholine during depression may affect both muscarinic and nicotinic acetylcholine receptors in a compensatory fashion. Increased functional dopamine and norepinephrine during mania on the other hand may affect receptor expression and functioning of dopamine reuptake transporters. Despite increasing evidence supporting this hypothesis, a relationship between these two neurotransmitter systems that could explain cycling between states of depression and mania is missing. Future studies should focus on the influence of environmental stimuli and genetic susceptibilities that may affect the catecholaminergic-cholinergic balance underlying cycling between the affective states. Overall, observations from recent studies add important data to this revised balance theory of bipolar disorder, renewing interest in this field of research. PMID:25107282

  14. Testing a Student Generated Hypothesis Using Student Data

    ERIC Educational Resources Information Center

    McGowan, Herle M.; Vaughan, Joel

    2012-01-01

    We describe an activity that allows students to experience the full process of a statistical investigation, from generating the research question, to collecting data and testing a hypothesis. Implementation of the activity is described both with and without use of clickers, handheld remotes that allow instant data collection.

  15. Hypothesis Generation, Sparse Categories, and the Positive Test Strategy

    ERIC Educational Resources Information Center

    Navarro, Daniel J.; Perfors, Amy F.

    2011-01-01

    We consider the situation in which a learner must induce the rule that explains an observed set of data but the hypothesis space of possible rules is not explicitly enumerated or identified. The first part of the article demonstrates that as long as hypotheses are sparse (i.e., index less than half of the possible entities in the domain) then a…

  16. Random Effects Structure for Confirmatory Hypothesis Testing: Keep It Maximal

    ERIC Educational Resources Information Center

    Barr, Dale J.; Levy, Roger; Scheepers, Christoph; Tily, Harry J.

    2013-01-01

    Linear mixed-effects models (LMEMs) have become increasingly prominent in psycholinguistics and related areas. However, many researchers do not seem to appreciate how random effects structures affect the generalizability of an analysis. Here, we argue that researchers using LMEMs for confirmatory hypothesis testing should minimally adhere to the…

  17. The Vascular Depression Hypothesis: Mechanisms Linking Vascular Disease with Depression

    PubMed Central

    Taylor, Warren D.; Aizenstein, Howard J.; Alexopoulos, George S.

    2013-01-01

    The ‘Vascular Depression’ hypothesis posits that cerebrovascular disease may predispose, precipitate, or perpetuate some geriatric depressive syndromes. This hypothesis stimulated much research that has improved our understanding of the complex relationships between late-life depression (LLD), vascular risk factors, and cognition. Succinctly, there are well-established relationships between late-life depression, vascular risk factors, and cerebral hyperintensities, the radiological hallmark of vascular depression. Cognitive dysfunction is common in late-life depression, particularly executive dysfunction, a finding predictive of poor antidepressant response. Over time, progression of hyperintensities and cognitive deficits predicts a poor course of depression and may reflect underlying worsening of vascular disease. This work laid the foundation for examining the mechanisms by which vascular disease influences brain circuits and influences the development and course of depression. We review data testing the vascular depression hypothesis with a focus on identifying potential underlying vascular mechanisms. We propose a disconnection hypothesis, wherein focal vascular damage and white matter lesion location is a crucial factor influencing neural connectivity that contributes to clinical symptomatology. We also propose inflammatory and hypoperfusion hypotheses, concepts that link underlying vascular processes with adverse effects on brain function that influence the development of depression. Testing such hypotheses will not only inform the relationship between vascular disease and depression but also provide guidance on the potential repurposing of pharmacological agents that may improve late-life depression outcomes. PMID:23439482

  18. Rational Variability in Children's Causal Inferences: The Sampling Hypothesis

    ERIC Educational Resources Information Center

    Denison, Stephanie; Bonawitz, Elizabeth; Gopnik, Alison; Griffiths, Thomas L.

    2013-01-01

    We present a proposal--"The Sampling Hypothesis"--suggesting that the variability in young children's responses may be part of a rational strategy for inductive inference. In particular, we argue that young learners may be randomly sampling from the set of possible hypotheses that explain the observed data, producing different hypotheses with…

  19. Animal Models for Testing the DOHaD Hypothesis

    EPA Science Inventory

    Since the seminal work in human populations by David Barker and colleagues, several species of animals have been used in the laboratory to test the Developmental Origins of Health and Disease (DOHaD) hypothesis. Rats, mice, guinea pigs, sheep, pigs and non-human primates have bee...

  20. Salary Discrimination: A Test of the Paradoxical Female Hypothesis.

    ERIC Educational Resources Information Center

    Young, I. Phillip

    1999-01-01

    To test the paradoxical female hypothesis (satisfaction with salary underpayment), researchers surveyed a random sample of school chief finance officers. Female officers (unlike their male counterparts) receiving less than their entitled salaries enjoyed the same level of pay satisfaction as female and male officers receiving more than their…

  1. Assessing Algebraic Solving Ability: A Theoretical Framework

    ERIC Educational Resources Information Center

    Lian, Lim Hooi; Yew, Wun Thiam

    2012-01-01

    Algebraic solving ability had been discussed by many educators and researchers. There exists no definite definition for algebraic solving ability as it can be viewed from different perspectives. In this paper, the nature of algebraic solving ability in terms of algebraic processes that demonstrate the ability in solving algebraic problem is…

  2. General hypothesis governing the growth of single-crystal nanowires

    NASA Astrophysics Data System (ADS)

    Mohammad, S. Noor

    2010-06-01

    The growth and growth rates of single-crystal nanowires by vapor phase mechanisms have been studied. A hypothesis has been proposed, which lays down foundation for the nanowire growth. It redefines the basic concepts of droplets from seeds and describes the fundamental basis of the adhesive properties of droplets. A set of droplet characteristics has been defined, a model in the framework of the hypothesis has been developed, and theoretical calculations have been performed. Experiments have also been carried out. Close correspondences between the theoretical and the experimental results lend support for the hypothesis and the model. Additional experimental evidences quantify the validity of the hypothesis. The calculated results resolve conflicts and controversies. They address the roles of catalysts in the growth of single-crystal nanowires. They shed light on the basic differences in the growth of thin and thick nanowires. They elucidate possible relationship between eutectic temperature and activation energy in the vapor-liquid-solid growth. They provide ground rules that govern the relative supplies of constituent vapor species for the growth of compound semiconductor nanowires. They explain how the same alloyed droplet (e.g., Au/Ga) is activated differently under the influence of different nonmetal elements of different nanowires (for example, As of GaAs, P of GaP, and N of GaN). They demonstrate, for example, that the nanowire growth may be achieved by means that creates thermodynamic imbalance and nanopores inside the seeds at temperatures far below the seed's melting temperature. Alloying in the vapor-solid-liquid mechanism is one such means where growth of even thick nanowires (radius of rD≥50 nm) is possible at temperatures far below the eutectic temperature. The hypothesis, is called the simple, novel, and malleable (SNM) hypothesis. This hypothesis, together with the model, appears to have solved the basic origin of the nanowire growth. It

  3. The cancer stem cell hypothesis: failures and pitfalls.

    PubMed

    Rahman, Maryam; Deleyrolle, Loic; Vedam-Mai, Vinata; Azari, Hassan; Abd-El-Barr, Muhammad; Reynolds, Brent A

    2011-02-01

    Based on the clonal evolution model and the assumption that the vast majority of tumor cells are able to propagate and drive tumor growth, the goal of cancer treatment has traditionally been to kill all cancerous cells. This theory has been challenged recently by the cancer stem cell (CSC) hypothesis, that a rare population of tumor cells, with stem cell characteristics, is responsible for tumor growth, resistance, and recurrence. Evidence for putative CSCs has been described in blood, breast, lung, prostate, colon, liver, pancreas, and brain. This new hypothesis would propose that indiscriminate killing of cancer cells would not be as effective as selective targeting of the cells that are driving long-term growth (ie, the CSCs) and that treatment failure is often the result of CSCs escaping traditional therapies.The CSC hypothesis has gained a great deal of attention because of the identification of a new target that may be responsible for poor outcomes of many aggressive cancers, including malignant glioma. As attractive as this hypothesis sounds, especially when applied to tumors that respond poorly to current treatments, we will argue in this article that the proposal of a stemlike cell that initiates and drives solid tissue cancer growth and is responsible for therapeutic failure is far from proven. We will present the point of view that for most advanced solid tissue cancers such as glioblastoma multiforme, targeting a putative rare CSC population will have little effect on patient outcomes. This review will cover problems with the CSC hypothesis, including applicability of the hierarchical model, inconsistencies with xenotransplantation data, and nonspecificity of CSC markers. PMID:21135745

  4. A critique of statistical hypothesis testing in clinical research

    PubMed Central

    Raha, Somik

    2011-01-01

    Many have documented the difficulty of using the current paradigm of Randomized Controlled Trials (RCTs) to test and validate the effectiveness of alternative medical systems such as Ayurveda. This paper critiques the applicability of RCTs for all clinical knowledge-seeking endeavors, of which Ayurveda research is a part. This is done by examining statistical hypothesis testing, the underlying foundation of RCTs, from a practical and philosophical perspective. In the philosophical critique, the two main worldviews of probability are that of the Bayesian and the frequentist. The frequentist worldview is a special case of the Bayesian worldview requiring the unrealistic assumptions of knowing nothing about the universe and believing that all observations are unrelated to each other. Many have claimed that the first belief is necessary for science, and this claim is debunked by comparing variations in learning with different prior beliefs. Moving beyond the Bayesian and frequentist worldviews, the notion of hypothesis testing itself is challenged on the grounds that a hypothesis is an unclear distinction, and assigning a probability on an unclear distinction is an exercise that does not lead to clarity of action. This critique is of the theory itself and not any particular application of statistical hypothesis testing. A decision-making frame is proposed as a way of both addressing this critique and transcending ideological debates on probability. An example of a Bayesian decision-making approach is shown as an alternative to statistical hypothesis testing, utilizing data from a past clinical trial that studied the effect of Aspirin on heart attacks in a sample population of doctors. As a big reason for the prevalence of RCTs in academia is legislation requiring it, the ethics of legislating the use of statistical methods for clinical research is also examined. PMID:22022152

  5. Distinguishing between the Partial-Mapping Preparation Hypothesis and the Failure-to-Engage Hypothesis of Residual Switch Costs

    ERIC Educational Resources Information Center

    Lindsen, Job P.; de Jong, Ritske

    2010-01-01

    Lien, Ruthruff, Remington, & Johnston (2005) reported residual switch cost differences between stimulus-response (S-R) pairs and proposed the partial-mapping preparation (PMP) hypothesis, which states that advance preparation will typically be limited to a subset of S-R pairs because of structural capacity limitations, to account for these…

  6. Optimizing Field Campaigns Using A Hypothesis Testing Framework

    NASA Astrophysics Data System (ADS)

    Harken, B. J.; Over, M. W.; Rubin, Y.

    2012-12-01

    Field campaigns in hydrogeology often aim to characterize aquifers for modeling and predicting flow and transport of contaminants to facilitate in some objective related to environmental protection or public health and safety. Many times these objectives depend on predicting the answer to a yes/no question, such as: will contaminant concentration in an aquifer surpass a threshold value? Will a contaminant reach a river outflow before it degrades? Is water from an extraction well safe for consumption? It remains difficult, however, to predict the extent to which a field campaign will improve modeling and prediction efforts or the chance of success in the original objective. Presented here is a method for designing field campaigns around the original objective by posing it in a hypothesis testing framework and optimizing campaigns with minimizing probability of error as the goal. The first step in this process is to formulate the null and alternative hypotheses, which represent the two possible outcomes of the yes/no question in the objective. The alternative hypothesis is the desirable outcome which requires a specified level of certainty to be accepted. The null hypothesis, on the other hand, is the "safe" fallback assumption, which is accepted if the alternative hypothesis lacks sufficient supporting evidence. Of key concern in designing field campaigns is the probability of making an error (Type I or Type II). A level of significance is chosen based on the severity of each type of error and the level of risk that is considered acceptable for each case. A field campaign can then be designed to gain enough information to reduce the probability of error to the acceptable level while expending as few resources as possible. A case study examined here is attempting to predict the arrival time of a contaminant in an aquifer. A scenario is first established in which a contaminant is travelling from a point source to a control plane, which could represent, for example, a

  7. Cardioprotective abilities of white wine.

    PubMed

    Cui, Jianhua; Tosaki, Arpad; Cordis, Gerald A; Bertelli, Alberto A E; Bertelli, Aldo; Maulik, Nilanjana; Das, Dipak K

    2002-05-01

    To study if white wines, like red wine, can also protect the heart from ischemia reperfusion injury, ethanol-free extracts of three different white wines (WW1, WW2 and WW3) (100 mg/100 g body weight) were given orally to Sprague Dawley rats (200 g body weight) for three weeks. Control rats were given water only for the same period of time. After three weeks, rats were anesthetized and sacrificed, and the hearts excised for the preparation of isolated working rat heart. All hearts were subjected to 30 min global ischemia followed by two hours of reperfusion. The results demonstrated that among the three different white wines, only WW2 showed cardioprotection as evidenced by improved post-ischemic ventricular recovery compared to control. The amount of malonaldehyde production in white wine-fed rat hearts were lower compared to that found in control hearts indicating reduced formation of the reactive oxygen species. In vitro studies using chemiluminescence technique revealed that these white wines scavenged both superoxide anions and hydroxyl radicals. The results of our study demonstrated that only WW2 white wine provided cardioprotection as evidenced by the improved the post-ischemic contractile recovery and reduced myocardial infarct size. The cardioprotective effect of this white wine may be attributed, at least in part, from its ability to function as an in vivo antioxidant. PMID:12074987

  8. A Hypothesis-Driven Approach to Site Investigation

    NASA Astrophysics Data System (ADS)

    Nowak, W.

    2008-12-01

    Variability of subsurface formations and the scarcity of data lead to the notion of aquifer parameters as geostatistical random variables. Given an information need and limited resources for field campaigns, site investigation is often put into the context of optimal design. In optimal design, the types, numbers and positions of samples are optimized under case-specific objectives to meet the information needs. Past studies feature optimal data worth (balancing maximum financial profit in an engineering task versus the cost of additional sampling), or aim at a minimum prediction uncertainty of stochastic models for a prescribed investigation budget. Recent studies also account for other sources of uncertainty outside the hydrogeological range, such as uncertain toxicity, ingestion and behavioral parameters of the affected population when predicting the human health risk from groundwater contaminations. The current study looks at optimal site investigation from a new angle. Answering a yes/no question under uncertainty directly requires recasting the original question as a hypothesis test. Otherwise, false confidence in the resulting answer would be pretended. A straightforward example is whether a recent contaminant spill will cause contaminant concentrations in excess of a legal limit at a nearby drinking water well. This question can only be answered down to a specified chance of error, i.e., based on the significance level used in hypothesis tests. Optimal design is placed into the hypothesis-driven context by using the chance of providing a false yes/no answer as new criterion to be minimized. Different configurations apply for one-sided and two-sided hypothesis tests. If a false answer entails financial liability, the hypothesis-driven context can be re-cast in the context of data worth. The remaining difference is that failure is a hard constraint in the data worth context versus a monetary punishment term in the hypothesis-driven context. The basic principle

  9. A test of the niche dimension hypothesis in an arid annual grassland.

    PubMed

    Harpole, W Stanley; Suding, Katharine N

    2011-05-01

    The niche dimension hypothesis predicts that greater numbers of limiting factors can allow greater numbers of species to coexist through species' tradeoffs for different limiting factors. A prediction that follows is that addition of multiple limiting resources to plant communities will increase productivity and simultaneously decrease diversity. Species loss due to limiting resource enrichment might occur through reducing the number of resources that species compete for or by changing the identity of limiting factors. We tested these predictions of the niche dimension hypothesis in an arid annual grassland by adding combinations of nutrients: nitrogen (N), phosphorus (P), and potassium with other elements (O). We found that species number decreased while biomass increased with greater numbers of added resources. In particular, N in combinations with P or O resulted in the greatest species loss, while biomass increased super-additively with N and P together. The addition of greater numbers of added nutrients decreased the availability of light and soil moisture, consistent with a potential shift in the identity of limiting resources. Species also differed in their responses to different combinations of N, P, and O, supporting predictions of resource-ratio tradeoffs. These results are particularly notable because this experiment was conducted during a drought year in an arid grassland (226 mm annual rainfall), which might have been expected to be water-rather than nutrient-limited. Our results support the hypothesis that plant diversity may be maintained by high-dimensional tradeoffs among species in their abilities to compete for multiple limiting factors. PMID:20963609

  10. Spatial abilities of medical graduates and choice of residency programs.

    PubMed

    Langlois, Jean; Wells, George A; Lecourtois, Marc; Bergeron, Germain; Yetisir, Elizabeth; Martin, Marcel

    2015-01-01

    Spatial abilities have been related in previous studies to three-dimensional (3D) anatomy knowledge and the performance in technical skills. The objective of this study was to relate spatial abilities to residency programs with different levels of content of 3D anatomy knowledge and technical skills. The hypothesis was that the choice of residency program is related to spatial abilities. A cohort of 210 medical graduates was enrolled in a prospective study in a 5-year experiment. Spatial abilities were measured with a redrawn Vandenberg and Kuse Mental Rotations Test (MRT) in two (MRTA) and three (MRTC) dimensions. Medical graduates were enrolled in Family Medicine (n = 76, 36.2%), Internal Medicine (64, 30.5%), Surgery (52, 24.8%), and Anesthesia (18, 8.6%). The assumption was that the level of 3D anatomy knowledge and technical skills content was higher in Surgery and Anesthesia compared to Family Medicine and Internal Medicine. Mean MRTA score of 12.4 (±SD 4.6), 12.0 (±4.3), 14.1 (±4.3), and 14.6 (±4.0) was obtained in Family Medicine, Internal Medicine, Surgery, and Anesthesia, respectively (P = 0.0176). Similarly, mean MRTC score of 8.0 (±4.4), 7.5 (±3.6), 8.5 (±3.9), and 7.9 (±4.1) was obtained (P = 0.5647). Although there was a tendency for lower MRTA score in Family Medicine and Internal Medicine compared to Surgery and Anesthesia, no statistically significant main effect of residency, year, sex, or the interactions were observed for the MRTA and MRTC. Studied sample of medical graduates was not found to choose their residency programs based on their innate spatial abilities. PMID:24953052

  11. UV-radiation-induced electron emission by hormones. Hypothesis for specific communication mechanisms

    NASA Astrophysics Data System (ADS)

    Getoff, Nikola

    2009-11-01

    The highlights of recently observed electron emission from electronically excited sexual hormones (17β-estradiol, progesterone, testosterone) and the phytohormone genistein in polar media are briefly reviewed. The electron yield, Q(e aq-), dependence from substrate concentration, hormone structure, polarity of solvent, absorbed energy and temperature are discussed. The hormones reactivity with e aq- and efficiency in electron transfer ensure them the ability to communicate with other biological systems in an organism. A hypothesis is presented for the explanation of the mechanisms of the distinct recognition of signals transmitted by electrons, originating from different types of hormones to receiving centres. Biological consequences of the electron emission in respect to cancer are mentioned.

  12. A developmental hypothesis to explain the multicentricity of breast cancer.

    PubMed

    Sharpe, C R

    1998-07-14

    In this article the author proposes that the multicentricity of breast cancer might be explained by a developmental hypothesis. Genetic alterations ("hits") occurring in epithelial stem cells during the development of the breast may be transmitted to populations of daughter cells during growth. As a result, areas of the breast may be predisposed to malignant transformation with the occurrence of further genetic hits. Areas with the same predisposition should be anatomically connected, and earlier hits during breast development should result in larger areas of predisposition. The multicentricity of breast cancer would be explained if multiple lesions--monoclonal for the predisposing genetic hit and polyclonal for subsequent hits--developed within a predisposed area. Multiple lesions arising from the spread of disease by extension would be expected to share many genetic hits. The author discusses the implications that further evidence supporting the developmental hypothesis would have for the prevention and treatment of breast cancer. PMID:9679488

  13. A developmental hypothesis to explain the multicentricity of breast cancer

    PubMed Central

    Sharpe, C R

    1998-01-01

    In this article the author proposes that the multicentricity of breast cancer might be explained by a developmental hypothesis. Genetic alterations ("hits") occurring in epithelial stem cells during the development of the breast may be transmitted to populations of daughter cells during growth. As a result, areas of the breast may be predisposed to malignant transformation with the occurrence of further genetic hits. Areas with the same predisposition should be anatomically connected, and earlier hits during breast development should result in larger areas of predisposition. The multicentricity of breast cancer would be explained if multiple lesions--monoclonal for the predisposing genetic hit and polyclonal for subsequent hits--developed within a predisposed area. Multiple lesions arising from the spread of disease by extension would be expected to share many genetic hits. The author discusses the implications that further evidence supporting the developmental hypothesis would have for the prevention and treatment of breast cancer. PMID:9679488

  14. Cooperation and human cognition: the Vygotskian intelligence hypothesis.

    PubMed

    Moll, Henrike; Tomasello, Michael

    2007-04-29

    Nicholas Humphrey's social intelligence hypothesis proposed that the major engine of primate cognitive evolution was social competition. Lev Vygotsky also emphasized the social dimension of intelligence, but he focused on human primates and cultural things such as collaboration, communication and teaching. A reasonable proposal is that primate cognition in general was driven mainly by social competition, but beyond that the unique aspects of human cognition were driven by, or even constituted by, social cooperation. In the present paper, we provide evidence for this Vygotskian intelligence hypothesis by comparing the social-cognitive skills of great apes with those of young human children in several domains of activity involving cooperation and communication with others. We argue, finally, that regular participation in cooperative, cultural interactions during ontogeny leads children to construct uniquely powerful forms of perspectival cognitive representation. PMID:17296598

  15. The Trivers-Willard hypothesis: sex ratio or investment?

    PubMed

    Veller, Carl; Haig, David; Nowak, Martin A

    2016-05-11

    The Trivers-Willard hypothesis has commonly been considered to predict two things. First, that a mother in good condition should bias the sex ratio of her offspring towards males (if males exhibit greater variation in reproductive value). Second, that a mother in good condition should invest more per son than per daughter. These two predictions differ empirically, mechanistically and, as we demonstrate here, theoretically too. We construct a simple model of sex allocation that allows simultaneous analysis of both versions of the Trivers-Willard hypothesis. We show that the sex ratio version holds under very general conditions, being valid for a large class of male and female fitness functions. The investment version, on the other hand, is shown to hold only for a small subset of male and female fitness functions. Our results help to make sense of the observation that the sex ratio version is empirically more successful than the investment version. PMID:27170721

  16. A phenotypic null hypothesis for the genetics of personality.

    PubMed

    Turkheimer, Eric; Pettersson, Erik; Horn, Erin E

    2014-01-01

    We review the genetically informed literature on the genetics of personality. Over the past century, quantitative genetic studies, using identical and fraternal twins, have demonstrated that differences in human personality are substantially heritable. We focus on more contemporary questions to which that basic observation has led. We examine whether differences in the heritability of personality are replicable across different traits, samples, and studies; how the heritability of personality relates to its reliability; and how behavior genetics can be employed in studies of validity, and we discuss the stability of personality in genetic and environmental variance. The appropriate null hypothesis in behavior genetics is not that genetic or environmental influence on personality is zero. Instead, we offer a phenotypic null hypothesis, which states that genetic variance is not an independent mechanism of individual differences in personality but rather a reflection of processes that are best conceptualized at the phenotypic level. PMID:24050184

  17. The functional matrix hypothesis revisited. 3. The genomic thesis.

    PubMed

    Moss, M L

    1997-09-01

    Although the initial versions of the functional matrix hypothesis (FMH) theoretically posited the ontogenetic primacy of "function," it is only in recent years that advances in the morphogenetic, engineering, and computer sciences provided an integrated experimental and numerical data base that permitted recent significant revisions of the FMH--revisions that strongly support the primary role of function in craniofacial growth and development. Acknowledging that the currently dominant scientific paradigm suggests that genomic, instead of epigenetic (functional) factors, regulate (cause, control) such growth, an analysis of this continuing controversy was deemed useful. Accordingly the method of dialectical analysis, is employed, stating a thesis, an antithesis, and a resolving synthesis based primarily on an extensive review of the pertinent current literature. This article extensively reviews the genomic hypothesis and offers a critique intended to remove some of the unintentional conceptual obscurantism that has recently come to surround it. PMID:9294365

  18. Isotopic Resonance Hypothesis: Experimental Verification by Escherichia coli Growth Measurements

    NASA Astrophysics Data System (ADS)

    Xie, Xueshu; Zubarev, Roman A.

    2015-03-01

    Isotopic composition of reactants affects the rates of chemical and biochemical reactions. As a rule, enrichment of heavy stable isotopes leads to progressively slower reactions. But the recent isotopic resonance hypothesis suggests that the dependence of the reaction rate upon the enrichment degree is not monotonous. Instead, at some ``resonance'' isotopic compositions, the kinetics increases, while at ``off-resonance'' compositions the same reactions progress slower. To test the predictions of this hypothesis for the elements C, H, N and O, we designed a precise (standard error +/-0.05%) experiment that measures the parameters of bacterial growth in minimal media with varying isotopic composition. A number of predicted resonance conditions were tested, with significant enhancements in kinetics discovered at these conditions. The combined statistics extremely strongly supports the validity of the isotopic resonance phenomenon (p << 10-15). This phenomenon has numerous implications for the origin of life studies and astrobiology, and possible applications in agriculture, biotechnology, medicine, chemistry and other areas.

  19. The Riemann hypothesis illuminated by the Newton flow of ζ

    NASA Astrophysics Data System (ADS)

    Neuberger, J. W.; Feiler, C.; Maier, H.; Schleich, W. P.

    2015-10-01

    We analyze the Newton flow of the Riemann zeta function ζ and rederive in an elementary way the Riemann-von Mangoldt estimate of the number of non-trivial zeros below a given imaginary part. The representation of the flow on the Riemann sphere highlights the importance of the North pole as the starting and turning point of the separatrices, that is of the continental divides of the Newton flow. We argue that the resulting patterns may lead to deeper insight into the Riemann hypothesis. For this purpose we also compare and contrast the Newton flow of ζ with that of a function which in many ways is similar to ζ, but violates the Riemann hypothesis. We dedicate this paper to the memory of Richard Lewis Arnowitt and his many contributions to general relativity and high energy physics.

  20. Health, self-regulation of bodily signals and intelligence: review and hypothesis.

    PubMed

    Fazekas, Christian; Leitner, Anton; Pieringer, Walter

    2010-12-01

    Childhood IQ and adult morbidity and mortality are known to be linked even beyond socioeconomic variables. Yet, their interrelations are insufficiently understood. It has been suggested that bodily sensations play a fundamental role in health-related self-regulation and that intelligence can influence the information processing of these somatic signals. This assumption is supported by reports on the influence of IQ on the exteroceptive (e.g. visual and auditory) and interoceptive (e.g. autonomic nervous system and posture) perception and processing of somatic information. Based on these findings the hypothesis of Psychosomatic Intelligence (PI) is introduced as an additional conceptual framework to probe the link between childhood IQ and adult health status. It implies a specific cognitive ability concerning the perception, interpretation, and self-regulation of bodily sensations. In this model, somatic signals are considered to reflect both intra-individual processes and individual-environment interactions. Based on this hypothesis the influence of intelligence on cognitive efforts to self-regulate somatic phenomena is amenable to systematic testing. PMID:21082270

  1. The manoeuvrability hypothesis to explain the maintenance of bilateral symmetry in animal evolution

    PubMed Central

    2012-01-01

    Background The overwhelming majority of animal species exhibit bilateral symmetry. However, the precise evolutionary importance of bilateral symmetry is unknown, although elements of the understanding of the phenomenon have been present within the scientific community for decades. Presentation of the hypothesis Here we show, with very simple physical laws, that locomotion in three-dimensional macro-world space is itself sufficient to explain the maintenance of bilateral symmetry in animal evolution. The ability to change direction, a key element of locomotion, requires the generation of instantaneous “pushing” surfaces, from which the animal can obtain the necessary force to depart in the new direction. We show that bilateral is the only type of symmetry that can maximize this force; thus, an actively locomoting bilateral body can have the maximal manoeuvrability as compared to other symmetry types. This confers an obvious selective advantage on the bilateral animal. Implications of the hypothesis These considerations imply the view that animal evolution is a highly channelled process, in which bilateral and radial body symmetries seem to be inevitable. Reviewers This article was reviewed by Gáspár Jékely, L. Aravind and Eugene Koonin. PMID:22789130

  2. Cultural evolution and prosociality: Widening the hypothesis space.

    PubMed

    Huebner, Bryce; Sarkissian, Hagop

    2016-01-01

    Norenzayan et al. suggest that Big Gods can be replaced by Big Governments. We examine forms of social and self-monitoring and ritual practice that emerged in Classical China, heterarchical societies like those that emerged in pre-Columbian Mesoamerica, and the contemporary Zapatista movement of Chiapas, and we recommend widening the hypothesis space to include these alternative forms of social organization. PMID:26948732

  3. Human Cancers Express a Mutator Phenotype: Hypothesis, Origin, and Consequences

    PubMed Central

    Loeb, Lawrence A.

    2016-01-01

    The mutator phenotype hypothesis was postulated more than 40 years ago. It was based on the multiple enzymatic steps required to precisely replicate the 6 billion bases in the human genome each time a normal cell divides. A reduction in this accuracy during tumor progression could be responsible for the striking heterogeneity of malignant cells within a tumor and for the rapidity by which cancers become resistant to therapy. PMID:27197248

  4. Visual perception and imagery: a new molecular hypothesis.

    PubMed

    Bókkon, I

    2009-05-01

    Here, we put forward a redox molecular hypothesis about the natural biophysical substrate of visual perception and visual imagery. This hypothesis is based on the redox and bioluminescent processes of neuronal cells in retinotopically organized cytochrome oxidase-rich visual areas. Our hypothesis is in line with the functional roles of reactive oxygen and nitrogen species in living cells that are not part of haphazard process, but rather a very strict mechanism used in signaling pathways. We point out that there is a direct relationship between neuronal activity and the biophoton emission process in the brain. Electrical and biochemical processes in the brain represent sensory information from the external world. During encoding or retrieval of information, electrical signals of neurons can be converted into synchronized biophoton signals by bioluminescent radical and non-radical processes. Therefore, information in the brain appears not only as an electrical (chemical) signal but also as a regulated biophoton (weak optical) signal inside neurons. During visual perception, the topological distribution of photon stimuli on the retina is represented by electrical neuronal activity in retinotopically organized visual areas. These retinotopic electrical signals in visual neurons can be converted into synchronized biophoton signals by radical and non-radical processes in retinotopically organized mitochondria-rich areas. As a result, regulated bioluminescent biophotons can create intrinsic pictures (depictive representation) in retinotopically organized cytochrome oxidase-rich visual areas during visual imagery and visual perception. The long-term visual memory is interpreted as epigenetic information regulated by free radicals and redox processes. This hypothesis does not claim to solve the secret of consciousness, but proposes that the evolution of higher levels of complexity made the intrinsic picture representation of the external visual world possible by regulated

  5. Neural networks supporting switching, hypothesis testing, and rule application.

    PubMed

    Liu, Zhiya; Braunlich, Kurt; Wehe, Hillary S; Seger, Carol A

    2015-10-01

    We identified dynamic changes in recruitment of neural connectivity networks across three phases of a flexible rule learning and set-shifting task similar to the Wisconsin Card Sort Task: switching, rule learning via hypothesis testing, and rule application. During fMRI scanning, subjects viewed pairs of stimuli that differed across four dimensions (letter, color, size, screen location), chose one stimulus, and received feedback. Subjects were informed that the correct choice was determined by a simple unidimensional rule, for example "choose the blue letter". Once each rule had been learned and correctly applied for 4-7 trials, subjects were cued via either negative feedback or visual cues to switch to learning a new rule. Task performance was divided into three phases: Switching (first trial after receiving the switch cue), hypothesis testing (subsequent trials through the last error trial), and rule application (correct responding after the rule was learned). We used both univariate analysis to characterize activity occurring within specific regions of the brain, and a multivariate method, constrained principal component analysis for fMRI (fMRI-CPCA), to investigate how distributed regions coordinate to subserve different processes. As hypothesized, switching was subserved by a limbic network including the ventral striatum, thalamus, and parahippocampal gyrus, in conjunction with cortical salience network regions including the anterior cingulate and frontoinsular cortex. Activity in the ventral striatum was associated with switching regardless of how switching was cued; visually cued shifts were associated with additional visual cortical activity. After switching, as subjects moved into the hypothesis testing phase, a broad fronto-parietal-striatal network (associated with the cognitive control, dorsal attention, and salience networks) increased in activity. This network was sensitive to rule learning speed, with greater extended activity for the slowest

  6. Parallelism Effects and Verb Activation: The Sustained Reactivation Hypothesis

    PubMed Central

    Shapiro, Lewis P.; Love, Tracy

    2010-01-01

    This study investigated the processes underlying parallelism by evaluating the activation of a parallel element (i.e., a verb) throughout and-coordinated sentences. Four points were tested: (1) approximately 1,600ms after the verb in the first conjunct (PP1), (2) immediately following the conjunction (PP2), (3) approximately 1,100ms after the conjunction (PP3), (4) at the end of the second conjunct (PP4). The results revealed no activation at PP1, suggesting activation related to the initial presentation had decayed by this point; however, activation was observed at PP2, PP3, and PP4, suggesting the conjunction elicits reactivation that is sustained throughout the second conjunct. These findings support a specific hypothesis about parallelism, the sustained reactivation hypothesis. This hypothesis claims that, in conjoined structures, a cue that is associated with parallelism elicits the reactivation of material from the first conjunct and that this activation is sustained until integration with the second conjunct can be completed. PMID:19774464

  7. The nephridial hypothesis of the gill slit origin.

    PubMed

    Ezhova, Olga V; Malakhov, Vladimir V

    2015-12-01

    Metameric gill slits are mysterious structures, unique for Chordata and Hemichordata, and also, perhaps, for the extinct Cambrian Calcichordata. There is a discussed hypothesis of the gill slits origin from the metameric nephridia. According to the hypothesis, the hypothetical metameric deuterostome ancestor had in each segment a pair of coelomoducts and a pair of intestinal pockets. In the anterior segments, the coelomoducts have fused with the intestinal pockets. As a result, each nephridium opened both into the gut and into the environment. Then the dissepiments and funnels reduced in all segments except the collar one. Thus, in recent enteropneusts, only the first pair of gill slits keeps the ancestral arrangement communicating at the same time with the gut, with the environment, and with the coelom of the preceding (collar) segment. In the anterior part of the branchio-genital trunk region of enteropneusts, the metameric intestinal pockets remained, as well as the metameric coelomoducts functioning as the ducts of the metameric gonads, i.e., as the gonoducts. The consequence of the hypothesis is that the metameric gill pores originate from the metameric excreting pores, and the metameric branchial sacs originate from the metameric endodermal pockets of the gut fused with the coelomoducts. The metameric gill slits by themselves correspond with metameric openings connecting the gut with metameric intestinal pockets. J. Exp. Zool. (Mol. Dev. Evol.) 324B: 647-652, 2015. © 2015 Wiley Periodicals, Inc. PMID:26227807

  8. Language control in bilinguals: The adaptive control hypothesis

    PubMed Central

    Abutalebi, Jubin

    2013-01-01

    Speech comprehension and production are governed by control processes. We explore their nature and dynamics in bilingual speakers with a focus on speech production. Prior research indicates that individuals increase cognitive control in order to achieve a desired goal. In the adaptive control hypothesis we propose a stronger hypothesis: Language control processes themselves adapt to the recurrent demands placed on them by the interactional context. Adapting a control process means changing a parameter or parameters about the way it works (its neural capacity or efficiency) or the way it works in concert, or in cascade, with other control processes (e.g., its connectedness). We distinguish eight control processes (goal maintenance, conflict monitoring, interference suppression, salient cue detection, selective response inhibition, task disengagement, task engagement, opportunistic planning). We consider the demands on these processes imposed by three interactional contexts (single language, dual language, and dense code-switching). We predict adaptive changes in the neural regions and circuits associated with specific control processes. A dual-language context, for example, is predicted to lead to the adaptation of a circuit mediating a cascade of control processes that circumvents a control dilemma. Effective test of the adaptive control hypothesis requires behavioural and neuroimaging work that assesses language control in a range of tasks within the same individual. PMID:25077013

  9. Conceptual biology, hypothesis discovery, and text mining: Swanson's legacy

    PubMed Central

    Bekhuis, Tanja

    2006-01-01

    Innovative biomedical librarians and information specialists who want to expand their roles as expert searchers need to know about profound changes in biology and parallel trends in text mining. In recent years, conceptual biology has emerged as a complement to empirical biology. This is partly in response to the availability of massive digital resources such as the network of databases for molecular biologists at the National Center for Biotechnology Information. Developments in text mining and hypothesis discovery systems based on the early work of Swanson, a mathematician and information scientist, are coincident with the emergence of conceptual biology. Very little has been written to introduce biomedical digital librarians to these new trends. In this paper, background for data and text mining, as well as for knowledge discovery in databases (KDD) and in text (KDT) is presented, then a brief review of Swanson's ideas, followed by a discussion of recent approaches to hypothesis discovery and testing. 'Testing' in the context of text mining involves partially automated methods for finding evidence in the literature to support hypothetical relationships. Concluding remarks follow regarding (a) the limits of current strategies for evaluation of hypothesis discovery systems and (b) the role of literature-based discovery in concert with empirical research. Report of an informatics-driven literature review for biomarkers of systemic lupus erythematosus is mentioned. Swanson's vision of the hidden value in the literature of science and, by extension, in biomedical digital databases, is still remarkably generative for information scientists, biologists, and physicians. PMID:16584552

  10. An Analysis of the Matching Hypothesis in Networks

    PubMed Central

    Jia, Tao; Spivey, Robert F.; Szymanski, Boleslaw; Korniss, Gyorgy

    2015-01-01

    The matching hypothesis in social psychology claims that people are more likely to form a committed relationship with someone equally attractive. Previous works on stochastic models of human mate choice process indicate that patterns supporting the matching hypothesis could occur even when similarity is not the primary consideration in seeking partners. Yet, most if not all of these works concentrate on fully-connected systems. Here we extend the analysis to networks. Our results indicate that the correlation of the couple’s attractiveness grows monotonically with the increased average degree and decreased degree diversity of the network. This correlation is lower in sparse networks than in fully-connected systems, because in the former less attractive individuals who find partners are likely to be coupled with ones who are more attractive than them. The chance of failing to be matched decreases exponentially with both the attractiveness and the degree. The matching hypothesis may not hold when the degree-attractiveness correlation is present, which can give rise to negative attractiveness correlation. Finally, we find that the ratio between the number of matched couples and the size of the maximum matching varies non-monotonically with the average degree of the network. Our results reveal the role of network topology in the process of human mate choice and bring insights into future investigations of different matching processes in networks. PMID:26083728

  11. Geometric and Topological Invariants of the Hypothesis Space

    NASA Astrophysics Data System (ADS)

    Rodríguez, Carlos C.

    2011-03-01

    The form and shape of a hypothesis space imposes natural objective constraints to any inferential process. This contribution summarizes what is currently known and the mathematics that are thought to be needed for new developments in this area. For example, it is well known that the quality of best possible estimators deteriorates with increasing volume, dimension and curvature of the hypothesis space. It is also known that regular statistical parametric models are finite dimensional Riemannian manifolds admitting a family of dual affine connections. Fisher information is the metric induced on the hypothesis space by the Hellinger distance. Nonparametric models are infinite dimensional manifolds. Global negative curvature implies asymptotic inadmissibility of uniform priors. When there is uncertainty about the model and the prior, entropic methods are more robust than standard Bayesian inference. The presence of some types of singularities allow the existence of faster than normal estimators …, etc. The large number of fundamental statistical concepts with geometric and topological content suggest to try to look at Riemannian Geometry, Algebraic Geometry, K-theory, Algebraic Topology, Knot-theory and other branches of current mathematics, not as empty esoteric abstractions but as allies for statistical inference.

  12. Language control in bilinguals: The adaptive control hypothesis.

    PubMed

    Green, David W; Abutalebi, Jubin

    2013-08-01

    Speech comprehension and production are governed by control processes. We explore their nature and dynamics in bilingual speakers with a focus on speech production. Prior research indicates that individuals increase cognitive control in order to achieve a desired goal. In the adaptive control hypothesis we propose a stronger hypothesis: Language control processes themselves adapt to the recurrent demands placed on them by the interactional context. Adapting a control process means changing a parameter or parameters about the way it works (its neural capacity or efficiency) or the way it works in concert, or in cascade, with other control processes (e.g., its connectedness). We distinguish eight control processes (goal maintenance, conflict monitoring, interference suppression, salient cue detection, selective response inhibition, task disengagement, task engagement, opportunistic planning). We consider the demands on these processes imposed by three interactional contexts (single language, dual language, and dense code-switching). We predict adaptive changes in the neural regions and circuits associated with specific control processes. A dual-language context, for example, is predicted to lead to the adaptation of a circuit mediating a cascade of control processes that circumvents a control dilemma. Effective test of the adaptive control hypothesis requires behavioural and neuroimaging work that assesses language control in a range of tasks within the same individual. PMID:25077013

  13. An Analysis of the Matching Hypothesis in Networks.

    PubMed

    Jia, Tao; Spivey, Robert F; Szymanski, Boleslaw; Korniss, Gyorgy

    2015-01-01

    The matching hypothesis in social psychology claims that people are more likely to form a committed relationship with someone equally attractive. Previous works on stochastic models of human mate choice process indicate that patterns supporting the matching hypothesis could occur even when similarity is not the primary consideration in seeking partners. Yet, most if not all of these works concentrate on fully-connected systems. Here we extend the analysis to networks. Our results indicate that the correlation of the couple's attractiveness grows monotonically with the increased average degree and decreased degree diversity of the network. This correlation is lower in sparse networks than in fully-connected systems, because in the former less attractive individuals who find partners are likely to be coupled with ones who are more attractive than them. The chance of failing to be matched decreases exponentially with both the attractiveness and the degree. The matching hypothesis may not hold when the degree-attractiveness correlation is present, which can give rise to negative attractiveness correlation. Finally, we find that the ratio between the number of matched couples and the size of the maximum matching varies non-monotonically with the average degree of the network. Our results reveal the role of network topology in the process of human mate choice and bring insights into future investigations of different matching processes in networks. PMID:26083728

  14. Investigation of the Frohlich hypothesis with high intensity terahertz radiation

    NASA Astrophysics Data System (ADS)

    Weightman, Peter

    2014-03-01

    This article provides an update to recent reviews of the Frohlich hypothesis that biological organisation is facilitated by the creation of coherent excited states driven by a flow of free energy provided by metabolic processes and mediated by molecular motions in the terahertz range. Sources of intense terahertz radiation have the potential to test this hypothesis since if it is true the growth and development of sensitive systems such as stem cells should be influenced by irradiation with intense terahertz radiation. A brief survey of recent work shows that it is not yet possible to make an assessment of the validity of the Frohlich hypothesis. Under some conditions a variety of cell types respond to irradiation with intense THz radiation in ways that involve changes in the activity of their DNA. In other experiments very intense and prolonged THz radiation has no measureable effect on the behavior of very sensitive systems such as stem cells. The wide variation in experimental conditions makes it impossible to draw any conclusions as to characteristics of THz radiation that will induce a response in living cells. It is possible that in environments suitable for their maintenance and growth cells are capable of compensating for any effects caused by exposure to THz radiation up to some currently unknown level of THz peak power.

  15. Musical expertise and the ability to imagine loudness.

    PubMed

    Bishop, Laura; Bailes, Freya; Dean, Roger T

    2013-01-01

    Most perceived parameters of sound (e.g. pitch, duration, timbre) can also be imagined in the absence of sound. These parameters are imagined more veridically by expert musicians than non-experts. Evidence for whether loudness is imagined, however, is conflicting. In music, the question of whether loudness is imagined is particularly relevant due to its role as a principal parameter of performance expression. This study addressed the hypothesis that the veridicality of imagined loudness improves with increasing musical expertise. Experts, novices and non-musicians imagined short passages of well-known classical music under two counterbalanced conditions: 1) while adjusting a slider to indicate imagined loudness of the music and 2) while tapping out the rhythm to indicate imagined timing. Subtests assessed music listening abilities and working memory span to determine whether these factors, also hypothesised to improve with increasing musical expertise, could account for imagery task performance. Similarity between each participant's imagined and listening loudness profiles and reference recording intensity profiles was assessed using time series analysis and dynamic time warping. The results suggest a widespread ability to imagine the loudness of familiar music. The veridicality of imagined loudness tended to be greatest for the expert musicians, supporting the predicted relationship between musical expertise and musical imagery ability. PMID:23460791

  16. Musical Expertise and the Ability to Imagine Loudness

    PubMed Central

    Bishop, Laura; Bailes, Freya; Dean, Roger T.

    2013-01-01

    Most perceived parameters of sound (e.g. pitch, duration, timbre) can also be imagined in the absence of sound. These parameters are imagined more veridically by expert musicians than non-experts. Evidence for whether loudness is imagined, however, is conflicting. In music, the question of whether loudness is imagined is particularly relevant due to its role as a principal parameter of performance expression. This study addressed the hypothesis that the veridicality of imagined loudness improves with increasing musical expertise. Experts, novices and non-musicians imagined short passages of well-known classical music under two counterbalanced conditions: 1) while adjusting a slider to indicate imagined loudness of the music and 2) while tapping out the rhythm to indicate imagined timing. Subtests assessed music listening abilities and working memory span to determine whether these factors, also hypothesised to improve with increasing musical expertise, could account for imagery task performance. Similarity between each participant’s imagined and listening loudness profiles and reference recording intensity profiles was assessed using time series analysis and dynamic time warping. The results suggest a widespread ability to imagine the loudness of familiar music. The veridicality of imagined loudness tended to be greatest for the expert musicians, supporting the predicted relationship between musical expertise and musical imagery ability. PMID:23460791

  17. Incorporating density dependence into the directed-dispersal hypothesis.

    PubMed

    Spiegel, Orr; Nathan, Ran

    2010-05-01

    The directed-dispersal (DrD) hypothesis, one of the main explanations for the adaptive value of seed dispersal, asserts that enhanced (nonrandom) arrival to favorable establishment sites is advantageous for plant fitness. However, as anticipated by the ideal free distribution theory, enhanced seed deposition may impair site suitability by increasing density-dependent mortality, thus negating the advantage postulated by the DrD hypothesis. Although the role of density effects is thoroughly discussed in the seed-dispersal literature, this DrD paradox remains largely overlooked. The paradox, however, may be particularly pronounced in animal-mediated dispersal systems, in which DrD is relatively common, because animals tend to generate local seed aggregations due to their nonrandom movements. To investigate possible solutions to the DrD paradox, we first introduce a simple analytical model that calculates the optimal DrD level at which seed arrival to favorable establishment sites yields maximal fitness gain in comparison to a null model of random arrival. This model predicts intermediate optimal DrD levels that correspond to various attributes of the plants, the dispersers, and the habitat. We then use a simulation model to explore the temporal dynamics of the invasion process of the DrD strategy in a randomly dispersed population, and the resistance of a DrD population against invasion of other dispersal strategies. This model demonstrates that some properties of the invasion process (e.g., mutant persistence ratio in the population and generations until initial establishment) are facilitated by high DrD levels, and not by intermediate levels as expected from the analytical model. These results highlight the need to revise the DrD hypothesis to include the countering effects of density-dependent mortality inherently imposed by enhanced arrival of seeds to specific sites. We illustrate how the revised hypothesis can elucidate previous results from empirical studies

  18. A longitudinal study of the interactive effects of perinatal complications and early family adversity on cognitive ability.

    PubMed

    Stanton, W R; McGee, R O; Silva, P A

    1989-06-01

    The effects of high, medium and low levels of perinatal complications and family adversity on intelligence quotient (IQ) scores were examined in a large sample of Dunedin children tested every second year in the age group 3-13 years. The aim was to test the hypothesis that favourable environmental circumstances attenuate the effects of perinatal complications on later cognitive ability. The results did not support this hypothesis but rather suggested that perinatal complications and family adversity have independent adverse effects on the development of children's cognitive ability. PMID:2764834

  19. Maintaining health by balancing microbial exposure and prevention of infection: the hygiene hypothesis versus the hypothesis of early immune challenge.

    PubMed

    Kramer, A; Bekeschus, S; Bröker, B M; Schleibinger, H; Razavi, B; Assadian, O

    2013-02-01

    The human immune system is inseparably bonded to an individual's personal micro-biome from birth to death. Since the beginning of life, commensal relationships have ensured the survival of micro- and macro-organisms within complex relationships. However, technological advances and altered lifestyle imposed new rules for this interaction during recent decades. It has been observed that reduced exposure to micro-organisms and parasites results in decreased morbidity and mortality, but is also associated with a rising prevalence of atopic disorders and autoimmune diseases, mostly in industrialized countries. This inverse relationship is described by the 'hygiene hypothesis', put forward in 1989, yet this term only imperfectly describes these observations, as excessive hygiene or hygienic measures may not directly be the central cause. The lack of appropriate immune stimulation during early childhood with the consequence of disturbed alignment in the sequence of encountering self- or non-self-antigens might account in the rise of atopy and autoimmune disease. For this reason we propose the term 'early immune challenge hypothesis'. This concept highlights the importance of immune priming in early life in the context of genetic, social, geographic, cultural, and economic background. Moreover, it emphasizes the central role of 'training' of regulatory T-cells through sufficient microbial exposure, leading to a robust, healthy balance between inflammation and anti-inflammation or immune tolerance. Insufficient exposure might result in abnormal immune regulatory development. Finally, it incorporates the idea of encountering 'old friends' - organisms that shaped our immune system during human phylogeny. This article gives a comprehensive overview of the relationship between microbial exposure, and the incidence of asthma and hay fever is outlined. Although the outcomes of these studies originally were interpreted in the framework of the hygiene hypothesis, they may suit the

  20. Innovative Allies: Spatial and Creative Abilities

    ERIC Educational Resources Information Center

    Coxon, Steve V.

    2012-01-01

    Spatial and creative abilities are important for innovations in science, technology, engineering, and math (STEM) fields, but talents are rarely developed from these abilities by schools, including among gifted children and adolescents who have a high potential to become STEM innovators. This article provides an overview of each ability and makes…

  1. A Structural Theory of Spatial Abilities.

    ERIC Educational Resources Information Center

    Guttman, Ruth; And Others

    1990-01-01

    After a brief review of the contributions of factor analysis and regional analysis to the elaboration of the structures of spatial abilities, a facet design and regional model for spatial abilities are presented. A cylindrical-wedge model is proposed to represent the correlational structure of spatial ability tests. (SLD)

  2. Explaining High Abilities of Nobel Laureates

    ERIC Educational Resources Information Center

    Shavinina, Larisa

    2004-01-01

    Although the Nobel Prize is associated with a rare, superior degree of intellectually creative achievement, high abilities of Nobel laureates are far from well explained. This paper argues that Nobel laureates' high abilities are determined in part by their extracognitive abilities, that is, specific feelings, preferences, beliefs and intuitive…

  3. Predicting Academic Achievement with Cognitive Ability

    ERIC Educational Resources Information Center

    Rohde, Treena Eileen; Thompson, Lee Anne

    2007-01-01

    The purpose of the present study is to explain variation in academic achievement with general cognitive ability and specific cognitive abilities. Grade point average, Wide Range Achievement Test III scores, and SAT scores represented academic achievement. The specific cognitive abilities of interest were: working memory, processing speed, and…

  4. A Critique of One-Tailed Hypothesis Test Procedures in Business and Economics Statistics Textbooks.

    ERIC Educational Resources Information Center

    Liu, Tung; Stone, Courtenay C.

    1999-01-01

    Surveys introductory business and economics statistics textbooks and finds that they differ over the best way to explain one-tailed hypothesis tests: the simple null-hypothesis approach or the composite null-hypothesis approach. Argues that the composite null-hypothesis approach contains methodological shortcomings that make it more difficult for…

  5. Movement Behavior and Host Location Ability of Corythucha ciliata

    PubMed Central

    Wu, Haiwei; Liu, Huanxiu

    2016-01-01

    Insect movement behavior is highly important in entomological population ecology, behavioral ecology and conservation, and in invasion ecology. In this study, we used an exotic lace bug (Corythucha ciliata) as a model organism to address the hypothesis that an insect species invading a new area has a high host location ability and rapid mobility by which it can be successfully carried to a new habitat. To test this hypothesis, three movement parameters (speed, duration and distance) of C. ciliata were assessed using laboratory and field observations. We found that 5th-instar nymphs of C. ciliata could move as far as 750 cm throughout their lifespan and that they moved an average of 0.038 m/min during the first 15 minutes after release, which was significantly farther than that of other instars. Of the tested nymphs, 21.85% could locate their host trees; of adults released 20 m from hosts, 11% reached the host trees on the first day, with an average flight distance of 22.14 m and a maximum flight distance of 27 m. The results of this study partly explain the mechanism of rapid diffusion. These results are also important for predicting population spread, improving eradication surveys, and managing future introductions of C. ciliata. PMID:27018584

  6. The Nebular Hypothesis - A False Paradigm Misleading Scientists

    NASA Astrophysics Data System (ADS)

    Myers, L. S.

    2005-05-01

    Science has reached a turning point in history after being misled for 250 years by Immanuel Kant's nebular hypothesis, the most fundamental assumption in science. The nebular hypothesis assumes all nine planets were created 4.5 billion years ago (Ga) as molten bodies that cooled with the same size and chemical composition they have today. Reevaluation of the nebular hypothesis proves it has been wrong since its inception. The proof has lain in plain sight for centuries-coal beds that could not have existed at the assumed time of creation because they formed on Earth's surface after creation of the planet when forests and swamps were exposed to solar energy. The coal beds were subsequently buried under overburden accreted in later millennia, steadily increasing Earth's mass and diameter. The coal beds and layers of overburden are proof Earth was not created 4.5 Ga but is growing and expanding by accretion of extraterrestrial mass and core expansion-a process termed "Accreation" (creation by accretion). Each process accelerates over time, but internal expansion exceeds the rate of external accretion. Because the nebular hypothesis is erroneous researchers assumed Earth's diameter never changes, and, faced with the possibility the Earth might be expanding after the Atlantic basin was discovered to be widening, this assumption led to the unworkable concept of subduction to maintain a constant diameter Earth. Subduction will prove to be one of the greatest errors in the history of science. Nullification of the nebular hypothesis also nullifies subduction and rejuvenates Carey's earth expansion theory. Accreation provides Carey's missing energy source and mechanism of expansion. Expansion is proved by morphologic evidence today's continents were once a single planetary landmass on a smaller Earth when today's oceans, covering 70% of the planet, did not exist 200-250 Ma. Despite hundreds of tons of meteorites and dust known to accrete daily, its cumulative effect has been

  7. How organisms do the right thing: The attractor hypothesis

    USGS Publications Warehouse

    Emlen, J.M.; Freeman, D.C.; Mills, A.; Graham, J.H.

    1998-01-01

    Neo-Darwinian theory is highly successful at explaining the emergence of adaptive traits over successive generations. However, there are reasons to doubt its efficacy in explaining the observed, impressively detailed adaptive responses of organisms to day-to-day changes in their surroundings. Also, the theory lacks a clear mechanism to account for both plasticity and canalization. In effect, there is a growing sentiment that the neo-Darwinian paradigm is incomplete, that something more than genetic structure, mutation, genetic drift, and the action of natural selection is required to explain organismal behavior. In this paper we extend the view of organisms as complex self-organizing entities by arguing that basic physical laws, coupled with the acquisitive nature of organisms, makes adaptation all but tautological. That is, much adaptation is an unavoidable emergent property of organisms' complexity and, to some a significant degree, occurs quite independently of genomic changes wrought by natural selection. For reasons that will become obvious, we refer to this assertion as the attractor hypothesis. The arguments also clarify the concept of "adaptation." Adaptation across generations, by natural selection, equates to the (game theoretic) maximization of fitness (the success with which one individual produces more individuals), while self-organizing based adaptation, within generations, equates to energetic efficiency and the matching of intake and biosynthesis to need. Finally, we discuss implications of the attractor hypothesis for a wide variety of genetical and physiological phenomena, including genetic architecture, directed mutation, genetic imprinting, paramutation, hormesis, plasticity, optimality theory, genotype-phenotype linkage and puncuated equilibrium, and present suggestions for tests of the hypothesis. ?? 1998 American Institute of Physics.

  8. Metabolic syndrome--from the neurotrophic hypothesis to a theory.

    PubMed

    Hristova, M G

    2013-10-01

    Metabolic syndrome (MetS) is a complex and heterogeneous disease characterized by central obesity, impaired glucose metabolism, dyslipidemia, arterial hypertension, insulin resistance and high-sensitivity C-reactive protein. In 2006, a neurotrophic hypothesis of the etiopathogenesis of MetS was launched. This hypothesis considered the neurotrophins a key factor in MetS development. Chronic inflammatory and/or psychoemotional distress provoke a series of neuroimmunoendocrine interactions such as increased tissue and plasma levels of proinflammatory cytokines and neurotrophins, vegetodystonia, disbalance of neurotransmitters, hormones and immunity markers, activation of the hypothalamo-pituitary-adrenal axis, insulin resistance, and atherosclerosis. An early and a late clinical stage in the course of MetS are defined. Meanwhile, evidence of supporting results from the world literature accumulates. This enables the transformation of the definition of the neurotrophic hypothesis into a neurotrophic theory of MetS. The important role of two neurotrophic factors, i.e. the nerve growth factor and brain-derived neurotrophic factor as well as of the proinflammatory cytokines, neurotransmitters, adipokines and, especially, of leptin for the development of MetS, obesity and type 2 diabetes mellitus is illustrated. There are reliable scientific arguments that the metabotrophic deficit due to reduced neurotrophins could be implicated in the pathogenesis of MetS, type 2 diabetes mellitus, and atherosclerosis as well. A special attention is paid to the activity of the hypothalamo-pituitary-adrenal axis after stress. The application of the neurotrophic theory of MetS could contribute to the etiological diagnosis and individualized management of MetS by eliminating the chronic distress, hyponeurotrophinemia and consequent pathology. It helps estimating the risk, defining the prognosis and implementing the effective prevention of this socially significant disease as evidenced by the

  9. Etiology of inflammatory bowel disease: A unified hypothesis

    PubMed Central

    Qin, Xiaofa

    2012-01-01

    Inflammatory bowel disease (IBD), including both ulcerative colitis (UC) and Crohn’s disease (CD), emerged and dramatically increased for about a century. Despite extensive research, its cause remains regarded as unknown. About a decade ago, a series of findings made me suspect that saccharin may be a key causative factor for IBD, through its inhibition on gut bacteria and the resultant impaired inactivation of digestive proteases and over digestion of the mucus layer and gut barrier (the Bacteria-Protease-Mucus-Barrier hypothesis). It explained many puzzles in IBD such as its emergence and temporal changes in last century. Recently I further found evidence suggesting sucralose may be also linked to IBD through a similar mechanism as saccharin and have contributed to the recent worldwide increase of IBD. This new hypothesis suggests that UC and CD are just two symptoms of the same morbidity, rather than two different diseases. They are both caused by a weakening in gut barrier and only differ in that UC is mainly due to increased infiltration of gut bacteria and the resultant recruitment of neutrophils and formation of crypt abscess, while CD is mainly due to increased infiltration of antigens and particles from gut lumen and the resultant recruitment of macrophages and formation of granulomas. It explained the delayed appearance but accelerated increase of CD over UC and many other phenomena. This paper aims to provide a detailed description of a unified hypothesis regarding the etiology of IBD, including the cause and mechanism of IBD, as well as the relationship between UC and CD. PMID:22553395

  10. Endogamy and suicide: An observation-based hypothesis.

    PubMed

    Jollant, F; Macdonald, C

    2015-11-01

    Suicide is a complex and multifactorial behavior, which is likely the result of distinct pathways in different individuals or groups. Endogamy has been associated with numerous diseases, including behavioral disorders. Here, we discuss the hypothesis of endogamy as one mechanism facilitating high rates of suicide in some small and isolated groups of people across the world. To support our hypothesis, we describe four geographically and culturally distinct populations (the Aguarunas of Peru, the Vaqueiros of Spain, the Baruyas of New Guinea, and the Palawans of the Philippines), which present the following characteristics: (1) a high level of isolation and endogamy; (2) very high rates of suicide restricted to one group with (3) adjacent groups of similar origin and culture displaying low rates of suicide. Within these four distinct populations, endogamy could act in one isolated group as the amplifier of both selected genetic risk alleles and microcultural values (e.g. suicide as an acceptable solution), beyond cultural and genetic traits shared by the whole population (and therefore found in all groups). Genetic and microcultural risk factors are transmitted through close kinship and imitation/modeling, and could interact to increase the frequency of vulnerable individuals leading, in turn, to heightened rates of suicide. Culture could sometimes additionally act by generating stressful conditions for some individuals (e.g. lower social status and maltreatment). In contrast to endogamy, suicide motives (notably interpersonal conflicts) and mental disorders appear to be universal risk factors. More investigation of this endogamy hypothesis is necessary, which could represent a singular case of gene-culture co-transmission and shed light on particular conditions of suicide genesis. PMID:26206761

  11. Inclination flattening and the geocentric axial dipole hypothesis [rapid communication

    NASA Astrophysics Data System (ADS)

    Tauxe, Lisa

    2005-05-01

    William Gilbert first articulated what has come to be known as the geocentric axial dipole hypothesis. The GAD hypothesis is the principle on which paleogeographic reconstructions rely to constrain paleolatitude. For decades, there have been calls for permanent non-dipole contributions to the time-averaged field. Recently, these have demanded large contributions of the axial octupole, which, if valid, would call into question the general utility of the GAD hypothesis. In the process of geological recording of the geomagnetic field, "Earth filters" distort the directions. Many processes, for example, sedimentary inclination flattening and random tilting, can lead to a net shallowing of the observed direction. Therefore, inclinations that are shallower than expected from GAD can be explained by recording biases, northward transport, or non-dipole geomagnetic fields. Using paleomagnetic data from the last 5 million years from well-constrained lava flow data allows the construction of a statistical geomagnetic field model. Such a model can predict not only the average expected direction for a given latitude, but also the shape of the distribution of directions produced by secular variation. The elongation of predicted directions varies as a function of latitude (from significantly elongate in the up/down direction at the equator to circularly symmetric at the poles). Sedimentary inclination flattening also works in a predictable manner producing elongations that are stretched side to side and the degree of flattening depending on the inclination of the applied field and a "flattening factor" f. The twin tools of the predicted elongation/inclination relationship characteristic of the geomagnetic field for the past 5 million years and the distortion of the directions predicted from sedimentary inclination flattening allows us to find the flattening factor that yields corrected directions with an elongation and average inclination consistent with the statistical field

  12. Aromatic herbs in Corsican blue tit nests: The 'Potpourri' hypothesis

    NASA Astrophysics Data System (ADS)

    Lambrechts, Marcel M.; Dos Santos, Anabelle

    2000-05-01

    This study reports that Corsican blue tit ( Parus caeruleus ogliastrae) nests contain between one to five aromatic herb species between the onset of egg laying till the chicks' finished growth 13 d after hatching. An herb removal experiment during the chick stage shows that blue tits bring fresh aromatic material 1-5 d after herb removal. Nests with a series of distinct odour classes easily perceived by humans have never been reported in birds. A new 'Potpourri' hypothesis is proposed that may explain the functional significance of this behaviour.

  13. Evaluation of the endogenous glucocorticoid hypothesis of denervation atrophy

    NASA Technical Reports Server (NTRS)

    Konagaya, Masaaki; Konagaya, Yoko; Max, Stephen R.

    1988-01-01

    The effects are studied of the oral administration of RU38486, a potent selective glucocorticoid antagonist, on muscle weight, non-collagen protein content, and selected enzyme activities (choline acetyltransferase, glucose 6-phosphate dehydrogenase, and glutamine synthetase) following denervation of rat skeletal muscle. Neither decreases in muscle weight, protein content, and choline acetyltransferase activity, nor increases in the activities of glucose 6-phosphate dehydrogernase and glutamine synthetase were affected by RU38486. These data do not support the hypothesis that denervation atrophy results from enhanced sensitivity of muscle to endogenous glucocorticoids.

  14. A multi-hypothesis tracker for clicking whales.

    PubMed

    Baggenstoss, Paul M

    2015-05-01

    This paper describes a tracker specially designed to track clicking beaked whales using widely spaced bottom-mounted hydrophones, although it can be adapted to different species and sensors. The input to the tracker is a sequence of static localization solutions obtained using time difference of arrival information at widely spaced hydrophones. To effectively handle input localizations with high ambiguity, the tracker is based on multi-hypothesis tracker concepts, so it considers all potential association hypotheses and keeps a large number of potential tracks in memory. The method is demonstrated on actual data and shown to successfully track multiple beaked whales at depth. PMID:25994688

  15. Robust operative diagnosis as problem solving in a hypothesis space

    NASA Technical Reports Server (NTRS)

    Abbott, Kathy H.

    1988-01-01

    This paper describes an approach that formulates diagnosis of physical systems in operation as problem solving in a hypothesis space. Such a formulation increases robustness by: (1) incremental hypotheses construction via dynamic inputs, (2) reasoning at a higher level of abstraction to construct hypotheses, and (3) partitioning the space by grouping fault hypotheses according to the type of physical system representation and problem solving techniques used in their construction. It was implemented for a turbofan engine and hydraulic subsystem. Evaluation of the implementation on eight actual aircraft accident cases involving engine faults provided very promising results.

  16. Hypothesis: gonadal temperature influences sex-specific imprinting

    PubMed Central

    Donti, Emilio

    2014-01-01

    Various explanations have been advanced for the evolution of genomic imprinting, the most popular of these being the parental conflict hypothesis. However, while this theory may explain why there has been selection for imprinting certain genes, it does not explain how the maternal and paternal genomes can be distinguished from each other. Here, we hypothesize that the temperature at which male and female gonads are physiologically exposed could be, at least for some loci, the primary factor leading to the different imprinting between the sexes. PMID:25202325

  17. Unemployment and civil commitment: a test of the intolerance hypothesis.

    PubMed

    Catalano, Ralph; Snowden, Lonnie; Shumway, Martha; Kessell, Eric

    2007-01-01

    We theorize that the reported association between economic indicators and the incidence of civil commitment for mental illness may result, at least in part, from reduced tolerance in the community for impaired behavior among minorities. Earlier work suggests that economically induced intolerance will be focused primarily on minority males. Based on this literature, we hypothesize that the median level of functioning among African-American males subjected to civil commitment will vary positively with earlier changes in the unemployment rate. The test applies Box-Jenkins methods to 156 months (August 1985-July 1998) of data from California. Consistent with theory, results support the hypothesis. PMID:17444533

  18. Yawning, fatigue, and cortisol: expanding the Thompson Cortisol Hypothesis.

    PubMed

    Thompson, Simon B N

    2014-10-01

    Yawning and its involvement in neurological disorders has become the new scientific conundrum. Cortisol levels are known to rise during stress and fatigue; yawning may occur when we are under stress or tired. However, the link between yawning, fatigue, and cortisol has not been fully understood. Expansion of the Thompson Cortisol Hypothesis proposes that the stress hormone, cortisol, is responsible for yawning and fatigue especially in people with incomplete innervation such as multiple sclerosis. This informs our understanding of the functional importance of the brain stem region of the brain in regulating stress and fatigue. PMID:25169036

  19. The biofield hypothesis: its biophysical basis and role in medicine.

    PubMed

    Rubik, Beverly

    2002-12-01

    This paper provides a scientific foundation for the biofield: the complex, extremely weak electromagnetic field of the organism hypothesized to involve electromagnetic bioinformation for regulating homeodynamics. The biofield is a useful construct consistent with bioelectromagnetics and the physics of nonlinear, dynamical, nonequilibrium living systems. It offers a unifying hypothesis to explain the interaction of objects or fields with the organism, and is especially useful toward understanding the scientific basis of energy medicine, including acupuncture, biofield therapies, bioelectromagnetic therapies, and homeopathy. The rapid signal propagation of electromagnetic fields comprising the biofield as well as its holistic properties may account for the rapid, holistic effects of certain alternative and complementary medical interventions. PMID:12614524

  20. HLA-sharing, recurrent spontaneous abortion, and the genetic hypothesis

    SciTech Connect

    Hedrick, P.W.

    1988-05-01

    A number of studies indicates that there is a high sharing of HLA antigens in couples having recurrent spontaneous abortions. The genetic hypothesis to explain this phenomenon suggests that this fetal loss results from homozygosity of recessive lethal or deleterius alleles in gametic disequilibrium with HLA antigens. Theory predicting the lethality rate is derived when antigens are shared at one, two or three loci, given the disequilibrium is absolute. In addition, the effects of partial disequilibrium, inbreeding, and segregation distortion on the lethal proportion are examined.

  1. Complement Propriety and Conspiracy in Nanomedicine: Perspective and a Hypothesis.

    PubMed

    Moghimi, Seyed Moein

    2016-04-01

    The complement system is the first line of body's defense against intruders and it acts as a functional bridge between innate and adaptive arms of the immune system. This commentary examines the key roles of complement activation in response to nanomedicine administration, including nucleic acid complexes. These comprise beneficial (eg, adjuvanticity) as well as adverse effects (eg, infusion-related reactions). Pigs (and sheep) are often used as predictive models of nanomedicine-mediated infusion-related reactions in humans. The validity of these models in relation to human responses is questioned, and an alternative hypothesis is presented. PMID:26720796

  2. The food-insecurity obesity paradox: A resource scarcity hypothesis.

    PubMed

    Dhurandhar, Emily J

    2016-08-01

    Food insecurity is paradoxically associated with obesity in the United States. Current hypotheses to explain this phenomenon are descriptive regarding the low food security population's dietary and physical activity habits, but are not mechanistic. Herein it is proposed that a resource scarcity hypothesis may explain this paradox, such that fattening is a physiologically regulated response to threatened food supply that occurs specifically in low social status individuals. Evidence that this may be occurring, the implications for addressing the food insecurity-obesity paradox, and future areas of research, are reviewed and discussed. PMID:27126969

  3. Hypothesis: Hemolytic Transfusion Reactions Represent an Alternative Type of Anaphylaxis

    PubMed Central

    Hod, Eldad A.; Sokol, Set A.; Zimring, James C.; Spitalnik, Steven L.

    2009-01-01

    Classical anaphylaxis is the most severe, and potentially fatal, type of allergic reaction, manifested by hypotension, bronchoconstriction, and vascular permeability. Similarly, a hemolytic transfusion reaction (HTR) is the most feared consequence of blood transfusion. Evidence for the existence of an alternative, IgG-mediated pathway of anaphylaxis may be relevant for explaining the pathophysiology of IgG-mediated-HTRs. The purpose of this review is to summarize the evidence for this alternative pathway of anaphylaxis and to present the hypothesis that an IgG-mediated HTR is one example of this type of anaphylaxis. PMID:18830382

  4. White matter microstructural properties correlate with sensorimotor synchronization abilities.

    PubMed

    Blecher, Tal; Tal, Idan; Ben-Shachar, Michal

    2016-09-01

    Sensorimotor synchronization (SMS) to an external auditory rhythm is a developed ability in humans, particularly evident in dancing and singing. This ability is typically measured in the lab via a simple task of finger tapping to an auditory beat. While simplistic, there is some evidence that poor performance on this task could be related to impaired phonological and reading abilities in children. Auditory-motor synchronization is hypothesized to rely on a tight coupling between auditory and motor neural systems, but the specific pathways that mediate this coupling have not been identified yet. In this study, we test this hypothesis and examine the contribution of fronto-temporal and callosal connections to specific measures of rhythmic synchronization. Twenty participants went through SMS and diffusion magnetic resonance imaging (dMRI) measurements. We quantified the mean asynchrony between an auditory beat and participants' finger taps, as well as the time to resynchronize (TTR) with an altered meter, and examined the correlations between these behavioral measures and diffusivity in a small set of predefined pathways. We found significant correlations between asynchrony and fractional anisotropy (FA) in the left (but not right) arcuate fasciculus and in the temporal segment of the corpus callosum. On the other hand, TTR correlated with FA in the precentral segment of the callosum. To our knowledge, this is the first demonstration that relates these particular white matter tracts with performance on an auditory-motor rhythmic synchronization task. We propose that left fronto-temporal and temporal-callosal fibers are involved in prediction and constant comparison between auditory inputs and motor commands, while inter-hemispheric connections between the motor/premotor cortices contribute to successful resynchronization of motor responses with a new external rhythm, perhaps via inhibition of tapping to the previous rhythm. Our results indicate that auditory

  5. Individual differences in the suppression of unwanted memories: the executive deficit hypothesis.

    PubMed

    Levy, Benjamin J; Anderson, Michael C

    2008-03-01

    When confronted with reminders to an unpleasant memory, people often try to prevent the unwanted memory from coming to mind. In this article, we review behavioral and neurocognitive evidence concerning the consequences of exerting such control over memory retrieval. This work indicates that suppressing retrieval is accomplished by control mechanisms that inhibit the unwanted memories, making them harder to recall later, even when desired. This process engages executive control mechanisms mediated by the lateral prefrontal cortex to terminate recollection-related activity in the hippocampus. Together, these findings specify a neurocognitive model of how memory control operates, suggesting that executive control may be an important means of down-regulating intrusive memories over time. We conclude by proposing that individual differences in the regulation of intrusive memories in the aftermath of trauma may be mediated by pre-existing differences in executive control ability. In support of this executive deficit hypothesis, we review the recent work indicating links between executive control ability and memory suppression. PMID:18242571

  6. Examination of the double-deficit hypothesis with adolescents and young adults with dyslexia.

    PubMed

    Nelson, Jason M

    2015-10-01

    The double-deficit hypothesis (DDH) of the developmental dyslexias (Wolf and Bowers, Journal of Educational Psychology, 91, 415-438, 1999) was investigated with 149 adolescents and young adults (age range = 16 to 24 years) with dyslexia. Confirmatory factor analysis indicated that a two-factor model with separate naming speed (NS) and phonological awareness (PA) constructs was superior to a one-factor model, supporting the assumption within the DDH that NS is a source of reading dysfunction separable from PA. Hierarchical multiple regression analyses resulted in findings that were only partially supportive of the DDH. NS was predictive of word reading, spelling, and reading fluency beyond PA and verbal intellectual ability, but not pseudoword reading and timed and untimed reading comprehension. Examination of DDH subtypes did not support the core assumption of the DDH that the double-deficit subtype would have more impaired reading skills than both of the single-deficit subtypes. The NS deficit subtype was found to be more prevalent than the double-deficit and PA deficit subtypes within the subgroup of dyslexics with impairment in reading fluency. Overall results provided mixed support for the DDH and pointed to the need for the inclusion of additional abilities within theories of the underlying mechanisms disrupted in dyslexia. PMID:25983024

  7. Face recognition: a model specific ability

    PubMed Central

    Wilmer, Jeremy B.; Germine, Laura T.; Nakayama, Ken

    2014-01-01

    In our everyday lives, we view it as a matter of course that different people are good at different things. It can be surprising, in this context, to learn that most of what is known about cognitive ability variation across individuals concerns the broadest of all cognitive abilities; an ability referred to as general intelligence, general mental ability, or just g. In contrast, our knowledge of specific abilities, those that correlate little with g, is severely constrained. Here, we draw upon our experience investigating an exceptionally specific ability, face recognition, to make the case that many specific abilities could easily have been missed. In making this case, we derive key insights from earlier false starts in the measurement of face recognition’s variation across individuals, and we highlight the convergence of factors that enabled the recent discovery that this variation is specific. We propose that the case of face recognition ability illustrates a set of tools and perspectives that could accelerate fruitful work on specific cognitive abilities. By revealing relatively independent dimensions of human ability, such work would enhance our capacity to understand the uniqueness of individual minds. PMID:25346673

  8. Face recognition: a model specific ability.

    PubMed

    Wilmer, Jeremy B; Germine, Laura T; Nakayama, Ken

    2014-01-01

    In our everyday lives, we view it as a matter of course that different people are good at different things. It can be surprising, in this context, to learn that most of what is known about cognitive ability variation across individuals concerns the broadest of all cognitive abilities; an ability referred to as general intelligence, general mental ability, or just g. In contrast, our knowledge of specific abilities, those that correlate little with g, is severely constrained. Here, we draw upon our experience investigating an exceptionally specific ability, face recognition, to make the case that many specific abilities could easily have been missed. In making this case, we derive key insights from earlier false starts in the measurement of face recognition's variation across individuals, and we highlight the convergence of factors that enabled the recent discovery that this variation is specific. We propose that the case of face recognition ability illustrates a set of tools and perspectives that could accelerate fruitful work on specific cognitive abilities. By revealing relatively independent dimensions of human ability, such work would enhance our capacity to understand the uniqueness of individual minds. PMID:25346673

  9. Testing the depth-differentiation hypothesis in a deepwater octocoral.

    PubMed

    Quattrini, Andrea M; Baums, Iliana B; Shank, Timothy M; Morrison, Cheryl L; Cordes, Erik E

    2015-05-22

    The depth-differentiation hypothesis proposes that the bathyal region is a source of genetic diversity and an area where there is a high rate of species formation. Genetic differentiation should thus occur over relatively small vertical distances, particularly along the upper continental slope (200-1000 m) where oceanography varies greatly over small differences in depth. To test whether genetic differentiation within deepwater octocorals is greater over vertical rather than geographical distances, Callogorgia delta was targeted. This species commonly occurs throughout the northern Gulf of Mexico at depths ranging from 400 to 900 m. We found significant genetic differentiation (FST = 0.042) across seven sites spanning 400 km of distance and 400 m of depth. A pattern of isolation by depth emerged, but geographical distance between sites may further limit gene flow. Water mass boundaries may serve to isolate populations across depth; however, adaptive divergence with depth is also a possible scenario. Microsatellite markers also revealed significant genetic differentiation (FST = 0.434) between C. delta and a closely related species, Callogorgia americana, demonstrating the utility of microsatellites in species delimitation of octocorals. Results provided support for the depth-differentiation hypothesis, strengthening the notion that factors covarying with depth serve as isolation mechanisms in deep-sea populations. PMID:25904664

  10. Asynchronous hatching and food limitation: a test of Lack's hypothesis

    USGS Publications Warehouse

    Skagen, Susan Knight

    1988-01-01

    Lack’s (1954, 1968) hypothesis that asynchronous hatching of altricial birds is an adaptive response to unpredictable food shortages during the breeding season was examined in the highly granivorous Zebra Finch (Poephila guttata). I compared growth and survival of nestlings in asynchronous and artificially created synchronous brood reared under food-limited and food-abundant conditions in an aviary. I also examined the role of parental experience on survival and growth of nestlings. There was no differential mortality of Zebra Finch nestlings due to either asynchrony or food abundance. Young in abundant food treatments grew more rapidly, however, than those in food restricted treatments. Heaviest Zebra Finch nestlings in a brood grew more quickly than their lightest siblings when food was limited, supporting Lack’s hypothesis. Further, differential survival of light and heavy siblings occurred when food was abundant, suggesting that asynchronous hatching can be maladaptive under some ecological conditions. Nestlings reared by inexperienced parents suffered greater mortality and slower growth when food was abundant than nestlings raised by experienced parents. Prefledging mass was correlated with size at adulthood.

  11. Learning when reward is delayed: a marking hypothesis.

    PubMed

    Lieberman, D A; McIntosh, D C; Thomas, G V

    1979-07-01

    Rats were trained on spatial discriminations in which reward was delayed for 1 min. Experiment 1 tested Lett's hypothesis that responses made in the home cage during the delay interval are less likely to interfere with learning than responses made in the maze. Experimental subjects were transferred to their home cages during the delay interval, and control subjects were picked up but then immediately replaced in the maze. Contrary to Lett's hypothesis, both groups learned. Further experiments suggested that handling following a choice response was the crucial variable in producing learning: No learning occurred when handling was delayed (Experiment 2) or omitted (Experiment 3). One possible explanation for the fact that handling facilitated learning is that it served to mark the preceding choice response in memory so that subjects were then more likely to recall it when subsequently reinforced. In accordance with this interpretation, learning was found to be just as strong when the choice response was followed by an intense light or noise as by handling (Experiment 4). The implication of marking for other phenomena such as avoidance, quasi-reinforcement, and the paradoxical effects of punishment is also discussed. PMID:528888

  12. Fungal communities as an experimental approach to Darwin's naturalization hypothesis.

    PubMed

    Morales, María Camila; Verdejo, Valentina; Orlando, Julieta; Carú, Margarita

    2016-01-01

    Darwin's naturalization hypothesis suggests that the success of an invasive species will be lower when colonizing communities are formed by phylogenetically related rather than unrelated species due to increased competition. Although microbial invasions are involved in both natural and anthropogenic processes, factors affecting the success of microbial invaders are unknown. A biological invasion assay was designed using Trichoderma cf. harzianum as the invader and two types of recipient communities assembled in microcosm assays: communities phylogenetically related to the invader, and communities phylogenetically unrelated to it. Both types of communities were invaded by T. cf. harzianum, and the success of colonization was monitored by qPCR; its effect on the genetic structure of recipient fungal communities was then assessed by DGGE profiles. T. cf. harzianum established itself in both communities, reaching 1000-10,000 times higher copy numbers in the non-related communities. However, invader establishment does not affect the structure of the invaded communities. These results suggest that the composition of recipient communities and their phylogenetic relationship to the invader affect the success of colonization by T. cf. harzianum. While this approach represents a very simplified assay, these microcosms enable an experimental test of Darwin's hypothesis in order to understand the biological invasion process in microbial communities. PMID:26506029

  13. Analogical reasoning and aging: the processing speed and inhibition hypothesis.

    PubMed

    Bugaiska, Aurélia; Thibaut, Jean-Pierre

    2015-01-01

    This study was designed to investigate the effect of aging on analogical reasoning by manipulating the strength of semantic association (LowAssoc or HighAssoc) and the number of distracters' semantic analogies of the A:B::C:D type and to determine which factors might be responsible for the age-related differences on analogical reasoning by testing two different theoretical frameworks: the inhibition hypothesis and the speed mediation hypothesis. We compared young adults and two groups of aging people (old and old-old) with word analogies of the A:B::C:D format. Results indicate an age-related effect on analogical reasoning, this effect being greatest with LowAssoc analogies. It was not associated with the presence of semantic distractors. Moreover, the results show that the variance part of the analogy task due to age was mainly explained by processing speed (rather than by inhibition) in the case of old participants and by both processing speed and inhibition in the old-old group. These results are discussed in relation to current models of aging and their interaction with the processes involved in analogical reasoning. PMID:25213435

  14. The Dendritic Cytoskeleton as a Computational Device: An Hypothesis

    NASA Astrophysics Data System (ADS)

    Priel, Avner; Tuszynski, Jack A.; Cantiello, Horacion F.

    This chapter presents a molecular-dynamical description of the functional role of cytoskeletal elements within the dendrites of a neuron. Our working hypothesis is that the dendritic cytoskeleton, including both microtubules (MTs) and actin filaments plays an active role in computations affecting neuronal function. These cytoskeletal elements are affected by, and in turn regulate, ion-channel activity, MAPs and other cytoskeletal proteins such as kinesin. A major hypothesis we advance here is that the C-termini protruding from the surface of a MT can exist in several conformational states, which lead to collective dynamical properties of the neuronal cytoskeleton. Further, these collective states of the C-termini on MTs have a significant effect on the ionic condensation and ion-cloud propagation that have physical similarities to those recently found in actin filaments. Our objective is to provide an integrated view of these phenomena in a bottom-up scheme. We outline substantial evidence to support our model and contend that ionic wave propagation along cytoskeletal structures impact channel function, and thus the computational capabilities of the dendritic tree and neuronal function at large.

  15. Multiple hypothesis testing in proteomics: a strategy for experimental work.

    PubMed

    Diz, Angel P; Carvajal-Rodríguez, Antonio; Skibinski, David O F

    2011-03-01

    In quantitative proteomics work, the differences in expression of many separate proteins are routinely examined to test for significant differences between treatments. This leads to the multiple hypothesis testing problem: when many separate tests are performed many will be significant by chance and be false positive results. Statistical methods such as the false discovery rate method that deal with this problem have been disseminated for more than one decade. However a survey of proteomics journals shows that such tests are not widely implemented in one commonly used technique, quantitative proteomics using two-dimensional electrophoresis. We outline a selection of multiple hypothesis testing methods, including some that are well known and some lesser known, and present a simple strategy for their use by the experimental scientist in quantitative proteomics work generally. The strategy focuses on the desirability of simultaneous use of several different methods, the choice and emphasis dependent on research priorities and the results in hand. This approach is demonstrated using case scenarios with experimental and simulated model data. PMID:21364085

  16. Evidence against a hypothesis of vestibular efferent function

    NASA Technical Reports Server (NTRS)

    Cochran, S. L.

    1994-01-01

    Efferent stimulation and nicotinic agonists can either decrease or increase the frequency of occurrence of EPSPs recorded from VIIIth nerve afferents in the frog. It has been hypothesized that the distribution of hair cell resting membrane potentials overlaps the equilibrium potential dictated by the nicotinic-gated channels on the hair cells. Nicotinic mediated increases in EPSP frequency would then be due to depolarization of hair cells that were more hyperpolarized at rest, while decreases in EPSP frequency would be due to hyperpolarization of hair cells more depolarized at rest. In order to test this hypothesis, while recording from afferents which showed an increase in EPSP frequency due to bath application of the nicotinic agonist DMPP (1,1-dimethyl-4-phenylpiperizinium iodide), hair cells were depolarized with 10 mM K+ in the bath, and then the effects of DMPP on EPSP frequency were assessed. In this situation, DMPP still increased EPSP frequency, suggesting that the equilibrium potential for the nicotinic-gated channel was much more positive than the resting potentials of the hair cells. An alternative hypothesis then seems likely, that the nicotinic receptors on hair cells are able to activate different iontophores that result in either hair cell depolarization or hyperpolarization, dependent upon which iontophore predominates in the hair cells innervating a particular afferent.

  17. A HYPOTHESIS FOR THE COLOR DIVERSITY OF THE KUIPER BELT

    SciTech Connect

    Brown, M. E.; Fraser, W. C.; Schaller, E. L.

    2011-10-01

    We propose a chemical and dynamical process to explain the surface colors of the Kuiper belt. In our hypothesis, the initial bulk compositions of the bodies themselves can be quite diverse-as is seen in comets-but the early surface compositions are set by volatile evaporation after the objects are formed. Strong gradients in surface composition, coupled with UV and particle irradiation, lead to the surface colors that are seen today. The objects formed in the inner part of the primordial belt retain only H{sub 2}O and CO{sub 2} as the major ice species on their surfaces. Irradiation of these species plausibly results in the dark neutrally colored centaurs and Kuiper belt objects (KBOs). Object formed further in the disk retain CH{sub 3}OH, which has been shown to lead to brighter redder surfaces after irradiation, as seen in the brighter redder centaurs and KBOs. Objects formed at the current location of the cold classical Kuiper belt uniquely retain NH{sub 3}, which has been shown to affect irradiation chemistry and could plausibly lead to the unique colors of these objects. We propose observational and experimental tests of this hypothesis.

  18. Pornography actresses: an assessment of the damaged goods hypothesis.

    PubMed

    Griffith, James D; Mitchell, Sharon; Hart, Christian L; Adams, Lea T; Gu, Lucy L

    2013-01-01

    The damaged goods hypothesis posits that female performers in the adult entertainment industry have higher rates of childhood sexual abuse (CSA), psychological problems, and drug use compared to the typical woman. The present study compared the self-reports of 177 porn actresses to a sample of women matched on age, ethnicity, and marital status. Comparisons were conducted on sexual behaviors and attitudes, self-esteem, quality of life, and drug use. Porn actresses were more likely to identify as bisexual, first had sex at an earlier age, had more sexual partners, were more concerned about contracting a sexually transmitted disease (STD), and enjoyed sex more than the matched sample, although there were no differences in incidence of CSA. In terms of psychological characteristics, porn actresses had higher levels of self-esteem, positive feelings, social support, sexual satisfaction, and spirituality compared to the matched group. Last, female performers were more likely to have ever used 10 different types of drugs compared to the comparison group. A discriminant function analysis was able to correctly classify 83% of the participants concerning whether they were a porn actress or member of the matched sample. These findings did not provide support for the damaged goods hypothesis. PMID:23167939

  19. HYPOTHESIS TESTING FOR HIGH-DIMENSIONAL SPARSE BINARY REGRESSION

    PubMed Central

    Mukherjee, Rajarshi; Pillai, Natesh S.; Lin, Xihong

    2015-01-01

    In this paper, we study the detection boundary for minimax hypothesis testing in the context of high-dimensional, sparse binary regression models. Motivated by genetic sequencing association studies for rare variant effects, we investigate the complexity of the hypothesis testing problem when the design matrix is sparse. We observe a new phenomenon in the behavior of detection boundary which does not occur in the case of Gaussian linear regression. We derive the detection boundary as a function of two components: a design matrix sparsity index and signal strength, each of which is a function of the sparsity of the alternative. For any alternative, if the design matrix sparsity index is too high, any test is asymptotically powerless irrespective of the magnitude of signal strength. For binary design matrices with the sparsity index that is not too high, our results are parallel to those in the Gaussian case. In this context, we derive detection boundaries for both dense and sparse regimes. For the dense regime, we show that the generalized likelihood ratio is rate optimal; for the sparse regime, we propose an extended Higher Criticism Test and show it is rate optimal and sharp. We illustrate the finite sample properties of the theoretical results using simulation studies. PMID:26246645

  20. Testing for Marshall-Lerner hypothesis: A panel approach

    NASA Astrophysics Data System (ADS)

    Azizan, Nur Najwa; Sek, Siok Kun

    2014-12-01

    The relationship between real exchange rate and trade balances are documented in many theories. One of the theories is the so-called Marshall-Lerner condition. In this study, we seek to test for the validity of Marshall-Lerner hypothesis, i.e. to reveal if the depreciation of real exchange rate leads to the improvement in trade balances. We focus our study in ASEAN-5 countries and their main trade partners of U.S., Japan and China. The dynamic panel data of pooled mean group (PMG) approach is used to detect the Marshall-Lerner hypothesis among ASEAN-5, between ASEAN-5 and U.S., between ASEAN-5 and Japan and between ASEAN-5 and China respectively. The estimation is based on the autoregressive Distributed Lag or ARDL model for the period of 1970-2012. The paper concludes that Marshal Lerner theory does not hold in bilateral trades in four groups of countries. The trade balances of ASEAN5 are mainly determined by the domestic income level and foreign production cost.

  1. Seat belt usage rates: a test of Peltzman's hypothesis.

    PubMed

    McCarthy, P S

    1986-10-01

    Despite the universally accepted belief that the use of seat belts would have a significant impact upon the number of vehicular fatalities, current evidence indicates that relatively few drivers employ their seat belts. Various hypotheses have been offered to explain this phenomenon, many of which conclude that a driver's decision to use a seat belt is independent of the risk experienced in his trip making. This paper develops an economic model which focuses upon the relationship between driver use of seat belts and the travel conditions under which trips are made. Using data obtained from a national survey of households, a binary logit model is developed to test the hypothesis that seat belt usage is influenced by the level of risk experienced in one's trip making. The estimation results were consistent with the underlying hypothesis that individuals travelling in more risky environments are more likely to use their seat belts. The econometric results are then employed to examine various policy issues, including the predicted use of seat belts for population sub-groups, driver response to the introduction of a small urban car, and the impact upon the probability of a fatality resulting from vehicle fleet downsizing. PMID:3768132

  2. Is the Amyloid Hypothesis of Alzheimer's disease therapeutically relevant?

    PubMed Central

    Teich, Andrew F.; Arancio, Ottavio

    2013-01-01

    The conventional view of AD (Alzheimer's disease) is that much of the pathology is driven by an increased load of β-amyloid in the brain of AD patients (the ‘Amyloid Hypothesis’). Yet, many therapeutic strategies based on lowering β-amyloid have so far failed in clinical trials. This failure of β-amyloid-lowering agents has caused many to question the Amyloid Hypothesis itself. However, AD is likely to be a complex disease driven by multiple factors. In addition, it is increasingly clear that β-amyloid processing involves many enzymes and signalling pathways that play a role in a diverse array of cellular processes. Thus the clinical failure of β-amyloid-lowering agents does not mean that the hypothesis itself is incorrect; it may simply mean that manipulating β-amyloid directly is an unrealistic strategy for therapeutic intervention, given the complex role of β-amyloid in neuronal physiology. Another possible problem may be that toxic β-amyloid levels have already caused irreversible damage to downstream cellular pathways by the time dementia sets in. We argue in the present review that a more direct (and possibly simpler) approach to AD therapeutics is to rescue synaptic dysfunction directly, by focusing on the mechanisms by which elevated levels of β-amyloid disrupt synaptic physiology. PMID:22891628

  3. [Hypothesis of evolutionary origin of several human and animal diseases].

    PubMed

    Pertseva, M N; Shpakov, A O

    2010-01-01

    Studies of our Laboratory in the field of molecular and evolutionary endocrinology have allowed us to put forward a hypothesis about evolutionary origin of endocrine and other diseases of human and animals. This hypothesis is considered using a model of hormonal signal systems. It is based on the concept formulated by the authors about molecular defects in hormonal signal systems as the key causes of endocrine diseases; on evolutionary conservatism of hormonal signal systems, which stems logically from the authors' concept of the prokaryotic origin and endosymbiotic appearance in the course of evolution of chemosignal systems in the higher eukaryotes; from the fact that the process of formation of hormonal signal systems with participation of endosymbiosis including the horizontal transfer of genes is accompanied by transfer not only of normal, but also of the defected genetic material. There are considered examples of the principal possibility of transfer of defected genes between bacteria and eukaryotic organisms. Analysis of the current literature allows suggesting inheritance of pathogenic factors from evolutionary ancestors in the lineage prokaryotes--lower eukaryotes--higher eukaryotes. PMID:20583590

  4. On the maternal transmission of immunity: a 'molecular attention' hypothesis.

    PubMed

    Anderson, R W

    1995-01-01

    Maternally-derived antibodies can provide passive protection to their offspring. More subtle phenomena associated with maternal antibodies concern their influence in shaping the immune repertoire and priming the neonatal immune response. These phenomena suggest that maternal antibodies play a role in the education of the neonatal immune system. The educational effects are thought to be mediated by idiotypic interactions among antibodies and B cells in the context of an idiotypic network. This paper proposes that maternal antibodies trigger localized idiotypic network activity that serves to amplify and translate information concerning the molecular shapes of potential antigens. The triggering molecular signals are contained in the binding regions of the antibody molecules. These antibodies form complexes and are taken up by antigen presenting cells or retained by follicular dendritic cells and thereby incorporated into more traditional cellular immune memory mechanisms. This mechanism for maternal transmission of immunity is termed the molecular attention hypothesis and is contrasted to the dynamic memory hypothesis. Experiments are proposed that may help indicate which models are more appropriate and will further our understanding of these intriguing natural phenomena. Finally, analogies are drawn to attention in neural systems. PMID:7727708

  5. A hypothesis for the 2007 dengue outbreak in Singapore.

    PubMed

    Massad, E; Coutinho, F A B; Ma, S; Burattini, M N

    2010-07-01

    A previous mathematical model explaining dengue in Singapore predicted a reasonable outbreak of about 6500 cases for 2006 and a very mild outbreak with about 2000 cases for 2007. However, only 3051 cases were reported in 2006 while more than 7800 were reported in the first 44 weeks of 2007. We hypothesized that the combination of haze with other local sources of particulate matter had a significant impact on mosquito life expectancy, significantly increasing their mortality rate. To test the hypothesis a mathematical model based on the reproduction number of dengue fever and aimed at comparing the impact of several possible alternative control strategies was proposed. This model also aimed at contributing to the understanding of the causes of dengue resurgence in Singapore in the last decade. The model's simulation demonstrated that an increase in mosquito mortality in 2006 and either a reduction in mortality or an increase in the carrying capacity of mosquitoes in 2007 explained the patterned observed in Singapore. Based on the model's simulation we concluded that the fewer than expected number of dengue cases in Singapore in 2006 was caused by an increase in mosquito mortality due to the disproportionate haze affecting the country that year and that particularly favourable environmental conditions in 2007 propitiated mosquitoes with a lower mortality rate, which explains the greater than expected number of dengue cases in 2007. Whether our hypothesis is plausible or not should be debated further. PMID:19653928

  6. Testing the depth-differentiation hypothesis in a deepwater octocoral

    PubMed Central

    Quattrini, Andrea M.; Baums, Iliana B.; Shank, Timothy M.; Morrison, Cheryl L.; Cordes, Erik E.

    2015-01-01

    The depth-differentiation hypothesis proposes that the bathyal region is a source of genetic diversity and an area where there is a high rate of species formation. Genetic differentiation should thus occur over relatively small vertical distances, particularly along the upper continental slope (200–1000 m) where oceanography varies greatly over small differences in depth. To test whether genetic differentiation within deepwater octocorals is greater over vertical rather than geographical distances, Callogorgia delta was targeted. This species commonly occurs throughout the northern Gulf of Mexico at depths ranging from 400 to 900 m. We found significant genetic differentiation (FST = 0.042) across seven sites spanning 400 km of distance and 400 m of depth. A pattern of isolation by depth emerged, but geographical distance between sites may further limit gene flow. Water mass boundaries may serve to isolate populations across depth; however, adaptive divergence with depth is also a possible scenario. Microsatellite markers also revealed significant genetic differentiation (FST = 0.434) between C. delta and a closely related species, Callogorgia americana, demonstrating the utility of microsatellites in species delimitation of octocorals. Results provided support for the depth-differentiation hypothesis, strengthening the notion that factors covarying with depth serve as isolation mechanisms in deep-sea populations. PMID:25904664

  7. Energy-squeeze model: further tests of the hypothesis

    SciTech Connect

    Santini, D.J.; Belak, F.J.

    1985-01-01

    In order to extend the time period for statistical tests of the validity of the energy-squeeze model, Shaw's data on the Value of Commodity Output since 1869 is used in conjunction with Historical Statistics of the US and an updated version of the data base compiled for the original paper. Use of Shaw's data for the period 1890 to 1933 allows the examination of the consistency of success of the hypothesis over almost a century. Measures of changes of the consumer's share of expenditures devoted to energy are used as predictors of changes in real Gross National Product (GNP) per capita, unemployment, and durable goods output (or purchases). The theory that a change in the rate of growth of the money supply determines economic activity is also tested. Comparison of the results for the two theories shows that they work about equally well under the tests used here. A ''cumulative pressure'' hypothesis asserting that it takes two years of cumulative energy-share or monetary-growth-rate changes to cause consumers to react strongly is found to be quite successful. The correlation of two-year energy-share and monetary-growth-rate shifts is found to be highest during depressions, suggesting that depression-inducing energy and monetary problems are fundamentally linked. 14 refs., 3 tabs.

  8. Partner choice, relationship satisfaction, and oral contraception: the congruency hypothesis.

    PubMed

    Roberts, S Craig; Little, Anthony C; Burriss, Robert P; Cobey, Kelly D; Klapilová, Kateřina; Havlíček, Jan; Jones, Benedict C; DeBruine, Lisa; Petrie, Marion

    2014-07-01

    Hormonal fluctuation across the menstrual cycle explains temporal variation in women's judgment of the attractiveness of members of the opposite sex. Use of hormonal contraceptives could therefore influence both initial partner choice and, if contraceptive use subsequently changes, intrapair dynamics. Associations between hormonal contraceptive use and relationship satisfaction may thus be best understood by considering whether current use is congruent with use when relationships formed, rather than by considering current use alone. In the study reported here, we tested this congruency hypothesis in a survey of 365 couples. Controlling for potential confounds (including relationship duration, age, parenthood, and income), we found that congruency in current and previous hormonal contraceptive use, but not current use alone, predicted women's sexual satisfaction with their partners. Congruency was not associated with women's nonsexual satisfaction or with the satisfaction of their male partners. Our results provide empirical support for the congruency hypothesis and suggest that women's sexual satisfaction is influenced by changes in partner preference associated with change in hormonal contraceptive use. PMID:24818612

  9. Ranging behavior drives parasite richness: A more parsimonious hypothesis.

    PubMed

    Bicca-Marques, Júlio César; Calegaro-Marques, Cláudia

    2016-09-01

    Parasitism is a ubiquitous interspecific interaction that may play an important role in the evolution of hosts and parasites, molding many aspects of their behavior and ecology. Detecting behavioral changes of hosts infected with parasites is not a straightforward task. Extrapolating from individual-level responses to group-level decision-making is still a much more complex challenge. The ranging behavior of hosts that live in social groups is a good example. Many hypotheses of the cause-effect relationship between this behavior and parasite diversity and load have been proposed. For instance, Brockmeyer et al. [2015, Am. J. Primatol. 77:1036-1048] recently suggested that the richness of protozoan parasites influences the daily path length of free-ranging mandrills. We believe that this explanation for the relationship contains several implicit assumptions. Therefore, we offer an alternative, more parsimonious hypothesis in which daily path length is the driver of parasite richness rather than its consequence. Our hypothesis only assumes that ranging farther exposes animals to a richer parasite diversity. We discuss the data required to test these alternative hypotheses and recall empirical evidence and theoretical modeling results supporting or rejecting their assumptions. We also propose a model of the expected outcomes in terms of species richness, load, intensity of infection, and within-group community similarity of non-lethal environmentally transmitted parasites in social animal groups showing distinct patterns of range use. Am. J. Primatol. 78:923-927, 2016. © 2016 Wiley Periodicals, Inc. PMID:27145909

  10. Cardiac torsion and electromagnetic fields: the cardiac bioinformation hypothesis.

    PubMed

    Burleson, Katharine O; Schwartz, Gary E

    2005-01-01

    Although in physiology the heart is often referred to as a simple piston pump, there are in fact two additional features that are integral to cardiac physiology and function. First, the heart as it contracts in systole, also rotates and produces torsion due to the structure of the myocardium. Second, the heart produces a significant electromagnetic field with each contraction due to the coordinated depolarization of myocytes producing a current flow. Unlike the electrocardiogram, the magnetic field is not limited to volume conduction and extends outside the body. The therapeutic potential for interaction of this cardioelectromagnetic field both within and outside the body is largely unexplored. It is our hypothesis that the heart functions as a generator of bioinformation that is central to normative functioning of body. The source of this bioinformation is based on: (1) vortex blood flow in the left ventricle; (2) a cardiac electromagnetic field and both; (3) heart sounds; and (4) pulse pressure which produce frequency and amplitude information. Thus, there is a multidimensional role for the heart in physiology and biopsychosocial dynamics. Recognition of these cardiac properties may result in significant implications for new therapies for cardiovascular disease based on increasing cardiac energy efficiency (coherence) and bioinformation from the cardioelectromagnetic field. Research studies to test this hypothesis are suggested. PMID:15823696

  11. A multi-pathway hypothesis for human visual fear signaling

    PubMed Central

    Silverstein, David N.; Ingvar, Martin

    2015-01-01

    A hypothesis is proposed for five visual fear signaling pathways in humans, based on an analysis of anatomical connectivity from primate studies and human functional connectvity and tractography from brain imaging studies. Earlier work has identified possible subcortical and cortical fear pathways known as the “low road” and “high road,” which arrive at the amygdala independently. In addition to a subcortical pathway, we propose four cortical signaling pathways in humans along the visual ventral stream. All four of these traverse through the LGN to the visual cortex (VC) and branching off at the inferior temporal area, with one projection directly to the amygdala; another traversing the orbitofrontal cortex; and two others passing through the parietal and then prefrontal cortex, one excitatory pathway via the ventral-medial area and one regulatory pathway via the ventral-lateral area. These pathways have progressively longer propagation latencies and may have progressively evolved with brain development to take advantage of higher-level processing. Using the anatomical path lengths and latency estimates for each of these five pathways, predictions are made for the relative processing times at selective ROIs and arrival at the amygdala, based on the presentation of a fear-relevant visual stimulus. Partial verification of the temporal dynamics of this hypothesis might be accomplished using experimental MEG analysis. Possible experimental protocols are suggested. PMID:26379513

  12. The delphic oracle and the ethylene-intoxication hypothesis.

    PubMed

    Foster, J; Lehoux, D

    2007-01-01

    An interdisciplinary team of scientists--including an archeologist, a geologist, a chemist, and a toxicologist--has argued that ethylene intoxication was the probable cause of the High Priestess of Delphi's divinatory (mantic) trances. The claim that the High Priestess of Delphi entered a mantic state because of ethylene intoxication enjoyed widespread reception in specialist academic journals, science magazines, and newspapers. This article uses a similar interdisciplinary approach to show that this hypothesis is implausible since it is based on problematic scientific and textual evidence, as well as a fallacious argument. The main issue raised by this counterargument is not that a particular scientific hypothesis or conjecture turned out to be false. (This is expected in scientific investigation.) Rather, the main issue is that it was a positivist disposition that originally led readers to associate the evidence presented in such a way that it seemed to point to the conclusion, even when the evidence did not support the conclusion. We conclude by observing that positivist dispositions can lead to the acceptance of claims because they have a scientific form, not because they are grounded in robust evidence and sound argument. PMID:17357391

  13. [Hygienic hypothesis in immunopathogenesis of inflammatory bowel disease].

    PubMed

    Gonciarz, Maciej; Szkudłapski, Dawid; Mularczyk, Aldona; Smagacz, Justyna

    2016-06-01

    Over three last decades, it has been noticed that morbidity of immunology-dependent illnesses, like asthma, inflammatory bowel disease or atopic dermatitis, apparently increased. That is the reason to focus on searching and exploring new ideas which could explain etiopathology of those diseases. In etiopathology the role of environmental factors is particularly emphasized. Research indicated the inverse relationship between the frequency of infectious and/ or parasites and autoimmune diseases. It was a leading subject of many studies what allowed to create a hypothesis which explains the phenomenon. The most original and innovative idea, named hygenic hypothesis, was proposed in the late 80s of the last century. Avoiding or limiting the contact with common bacteria and parasites in well-and very well-developed countries probably caused depletion of immune memory which resulted in the hypersensitive response after exposure to general factors. Nowadays, autoimmunological diseases make really serious problem for medical care in the United States of America and Western European countries, ranking just behind cardiovascular diseases, cancer and metabolic sicknesses. PMID:27403907

  14. Romanticism and schizophrenia. Second part: The intimacy hypothesis.

    PubMed

    López-Ibor, Juan J; López-Ibor, María I

    2014-01-01

    In the first part of this article we have analyzed the evidence supporting the recency hypothesis of schizophrenia and also what we can call the intimate nature of the disease. In this part we highlight the role of certain cultural aspects that have been ignored up to now, aspects that are associated with deep changes in the Weltanschauung and systems of beliefs on human nature brought up by the late Modernism, specifically by Romanticism. The description of the main characteristics of Romanticism, starting with the “discovery of intimacy”, leads to the conclusion that the characteristic alteration of subjectivity and ipseity of the disease appears to be a vulnerability factor when somebody has to face the new challenges raise Romanticism. The consideration of Hölderlin’s literary achievements and the deep psychological drama prevailing in them, makes explicit how the late modern human being finds in Romanticism the source of creativity and personal development but also the threat of his or her own destruction. Finally we link our hypothesis with recent genetic perspectives that consider sets of diseases associated to the same gene or genes (diseasome). In any case the process of associating the traits of Late Modernism and Romanticism with the core features of schizophrenia allows to consider the amalgamation of insanity with society, both at a general level an in what concerns individual patients, paving the way for novel therapeutic strategies. PMID:25179093

  15. The Hypothesis of Nuclear Fusion in Condensed Matter: An Update

    NASA Astrophysics Data System (ADS)

    Jones, Steven; Ellsworth, John; Rees, Lawrence

    2004-05-01

    In our 1986 and1989 papers, we discussed the hypothesis of nuclear fusion in condensed matter and particularly in the planets and provided supporting evidence.[1,2] We continue to assert that non-thermonuclear d-Z fusion (including but not limited to d-d fusion) may occur in the core-region of the earth, and generally in hydrogen-bearing metals and minerals which are subjected to extreme off-equilibrium conditions. This hypothesis can be tested by measuring tritium and helium-3 in magmatic fluids from hot-spot volcanoes which tap plumes arising from the core-mantle boundary. In particular, magmatic waters of Kilauea, Loihi, and Icelandic volcanoes are predicted to contain significant tritium. Magmatic emissions of Kilauea demonstrated anomalous tritium content over twelve years ago[3], and a re-test of Kilauea emissions is urged along with further laboratory experiments. [1] C. DeW. Van Siclen and S. E. Jones, "Piezonuclear fusion in isotopic hydrogen molecules," J. Phys. G: Nucl. Phys. 12: 213-221 (March 1986). [2] S. E. Jones, et al., Observation of Cold Nuclear Fusion in Condensed Matter, Nature 338: 737-740 (April 1989). [4] F. Goff and G. M. McMurtry, "Tritium and stable isotopes of magmatic waters," J. Volcanology and Geothermal Research, 97: 347-396 (2000)

  16. Random effects structure for confirmatory hypothesis testing: Keep it maximal

    PubMed Central

    Barr, Dale J.; Levy, Roger; Scheepers, Christoph; Tily, Harry J.

    2013-01-01

    Linear mixed-effects models (LMEMs) have become increasingly prominent in psycholinguistics and related areas. However, many researchers do not seem to appreciate how random effects structures affect the generalizability of an analysis. Here, we argue that researchers using LMEMs for confirmatory hypothesis testing should minimally adhere to the standards that have been in place for many decades. Through theoretical arguments and Monte Carlo simulation, we show that LMEMs generalize best when they include the maximal random effects structure justified by the design. The generalization performance of LMEMs including data-driven random effects structures strongly depends upon modeling criteria and sample size, yielding reasonable results on moderately-sized samples when conservative criteria are used, but with little or no power advantage over maximal models. Finally, random-intercepts-only LMEMs used on within-subjects and/or within-items data from populations where subjects and/or items vary in their sensitivity to experimental manipulations always generalize worse than separate F1 and F2 tests, and in many cases, even worse than F1 alone. Maximal LMEMs should be the ‘gold standard’ for confirmatory hypothesis testing in psycholinguistics and beyond. PMID:24403724

  17. An isomorphic mapping hypothesis of the grid representation

    PubMed Central

    Brecht, Michael; Ray, Saikat; Burgalossi, Andrea; Tang, Qiusong; Schmidt, Helene; Naumann, Robert

    2014-01-01

    We introduce a grid cell microcircuit hypothesis. We propose the ‘grid in the world’ (evident in grid cell discharges) is generated by a ‘grid in the cortex’. This cortical grid is formed by patches of calbindin-positive pyramidal neurons in layer 2 of medial entorhinal cortex (MEC). Our isomorphic mapping hypothesis assumes three types of isomorphism: (i) metric correspondence of neural space (the two-dimensional cortical sheet) and the external two-dimensional space within patches; (ii) isomorphism between cellular connectivity matrix and firing field; (iii) isomorphism between single cell and population activity. Each patch is a grid cell lattice arranged in a two-dimensional map of space with a neural : external scale of approximately 1 : 2000 in the dorsal part of rat MEC. The lattice behaves like an excitable medium with neighbouring grid cells exciting each other. Spatial scale is implemented as an intrinsic scaling factor for neural propagation speed. This factor varies along the dorsoventral cortical axis. A connectivity scheme of the grid system is described. Head direction input specifies the direction of activity propagation. We extend the theory to neurons between grid patches and predict a rare discharge pattern (inverted grid cells) and the relative location and proportion of grid cells and spatial band cells. PMID:24366133

  18. Cancer link to magnetic field exposure: a hypothesis

    SciTech Connect

    Easterly, C.E.

    1981-08-01

    The hypothesis is presented for a relationship between exposure to magnetic fields and the induction of cancer: alterations in the mitotic processes caused by exposure to magnetic fields can provide a proliferative stimulus to latent tumor cells, thereby leading to the expression of malignant neoplasia. In a review of the literature, it was found that most of the magnetic field data cited were taken in connection with static field conditions. Neither 0 or 60 Hz fields interact with biological tissue in a manner analogous to the resonant energy absorption found with microwave exposure. Some evidence, however, indicates similar biologic effects for both frequencies with those at 60 Hz being somewhat more pronounced. While there is no data relating magnetic field exposure to any parameter directly related to cellular toxicity or cellular death, there is a growing data base indicating increases or decreases in cellular reproductive rate and function consequent to magnetic field exposure. Therefore, it appears that mathematical development of the hypothesis discussed is possible utilizing available information. (JMT)

  19. An empirical assessment of the "healthy prisoner hypothesis".

    PubMed

    Baćak, Valerio; Wildeman, Christopher

    2015-08-01

    Lower mortality among inmates, compared to the general population, is typically ascribed to access to health care during incarceration and the low risk of death due to homicide, accidents, and drug overdose. In this study, we test an alternative explanation based on selection of healthy individuals into jails and prisons-"the healthy prisoner hypothesis." According to this hypothesis, inmates have to be healthy to commit crimes and become incarcerated, which explains why they experience lower mortality than comparable segments of the general population. Using ten waves of data from the National Longitudinal Survey of Youth 1997, we compare individuals who become incarcerated the following year to those who do not on four measures of health-depression, self-rated health, functional limitations, and injury or illness requiring medical attention. Results from matched samples indicate that future inmates are hardly ever in significantly better health the year prior to their incarceration. These findings strongly suggest that the paradoxical mortality advantage of inmates is not due to health selection. PMID:26114835

  20. The szilard hypothesis on the nature of aging revisited.

    PubMed

    Zetterberg, Henrik; Båth, Magnus; Zetterberg, Madeleine; Bernhardt, Peter; Hammarsten, Ola

    2009-05-01

    This year marks the 50th anniversary of a nearly forgotten hypothesis on aging by Leo Szilard, best known for his pioneering work in nuclear physics, his participation in the Manhattan Project during World War II, his opposition to the nuclear arms race in the postwar era, and his pioneering ideas in biology. Given a specific set of assumptions, Szilard hypothesized that the major reason for the phenomenon of aging was aging hits, e.g., by ionizing radiation, to the gene-bearing chromosomes and presented a mathematical target-hit model enabling the calculation of the average and maximum life span of a species, as well as the influence of increased exposure to DNA-damaging factors on life expectancy. While many new findings have cast doubt on the specific features of the model, this was the first serious effort to posit accumulated genetic damage as a cause of senescence. Here, we review Szilard's assumptions in the light of current knowledge on aging and reassess his mathematical model in an attempt to reach a conclusion on the relevance of Szilard's aging hypothesis today. PMID:19403867

  1. The Szilard Hypothesis on the Nature of Aging Revisited

    PubMed Central

    Zetterberg, Henrik; Båth, Magnus; Zetterberg, Madeleine; Bernhardt, Peter; Hammarsten, Ola

    2009-01-01

    This year marks the 50th anniversary of a nearly forgotten hypothesis on aging by Leo Szilard, best known for his pioneering work in nuclear physics, his participation in the Manhattan Project during World War II, his opposition to the nuclear arms race in the postwar era, and his pioneering ideas in biology. Given a specific set of assumptions, Szilard hypothesized that the major reason for the phenomenon of aging was aging hits, e.g., by ionizing radiation, to the gene-bearing chromosomes and presented a mathematical target-hit model enabling the calculation of the average and maximum life span of a species, as well as the influence of increased exposure to DNA-damaging factors on life expectancy. While many new findings have cast doubt on the specific features of the model, this was the first serious effort to posit accumulated genetic damage as a cause of senescence. Here, we review Szilard's assumptions in the light of current knowledge on aging and reassess his mathematical model in an attempt to reach a conclusion on the relevance of Szilard's aging hypothesis today. PMID:19403867

  2. Isotopic Resonance Hypothesis: Experimental Verification by Escherichia coli Growth Measurements

    PubMed Central

    Zubarev, Roman A.

    2015-01-01

    Isotopic composition of reactants affects the rates of chemical and biochemical reactions. As a rule, enrichment of heavy stable isotopes leads to progressively slower reactions. But the recent isotopic resonance hypothesis suggests that the dependence of the reaction rate upon the enrichment degree is not monotonous. Instead, at some “resonance” isotopic compositions, the kinetics increases, while at “off-resonance” compositions the same reactions progress slower. To test the predictions of this hypothesis for the elements C, H, N and O, we designed a precise (standard error ±0.05%) experiment that measures the parameters of bacterial growth in minimal media with varying isotopic composition. A number of predicted resonance conditions were tested, with significant enhancements in kinetics discovered at these conditions. The combined statistics extremely strongly supports the validity of the isotopic resonance phenomenon (p ≪ 10−15). This phenomenon has numerous implications for the origin of life studies and astrobiology, and possible applications in agriculture, biotechnology, medicine, chemistry and other areas. PMID:25782666

  3. Socially desirable responding on the web: investigating the candor hypothesis.

    PubMed

    Risko, Evan F; Quilty, Lena C; Oakman, Jonathan M

    2006-12-01

    The investigation presented here explores the hypothesis that participants are less likely to respond in a socially desirable fashion on self-report questionnaires completed on the Web relative to those completed in the laboratory--the candor hypothesis. A battery of social desirability questionnaires (i.e., Balanced Inventory of Desirable Responding [Paulhaus, 1984], Marlowe-Crowne Social Desirability Scale [Crowne & Marlowe, 1964], Eysenck Personality Questionnaire-Revised Lie Scale [Eysenck & Eysenck, 1994]) was administered to 3 groups: 2 groups consisted of undergraduate participants who were randomly assigned to complete the measures either in the laboratory (n = 60) or on the Web (n = 60), and 1 group consisted of self-selected participants who visited our experimental Web page and completed the measures online (n = 284). This design allowed us to assess the role of Web administration while controlling for differences in sample type, an oft-neglected issue in the Web literature. Results do not support the claim that administering self-report measures over the Web results in a decrease in socially desirable responding. Furthermore, these findings highlight the problems associated with confounding sample and medium. Implications for the use of Web as a research tool are discussed. PMID:17134335

  4. The community conditioning hypothesis and its application to environmental toxicology

    SciTech Connect

    Matthews, R.A.; Landis, W.G.; Matthews, G.B.

    1996-04-01

    In this paper the authors present the community conditions hypothesis, ecological communities retain information bout events in their history. This hypothesis, which was derived from the concept of nonequilibrium community ecology, was developed as a framework for understanding the persistence of dose-related responses in multispecies toxicity tests. The authors present data from three standardized aquatic microcosm (SAM) toxicity tests using the water-soluble fractions from turbine fuels (Jet-A, JP-4, and JP-8). In all three tests, the toxicants depressed the Daphnia populations for several weeks, which resulted in algal blooms in the dosed microcosms due to lower predation rates. These effects were short-lived, and by the second and third months of the experiments, the Daphnia populations appeared to have recovered. However, multivariate analysis of the data released dose/response differences that reappeared during the later part of the tests, often due to differences in other consumers (rotifers, ostracods, ciliates), or algae that are not normally consumed (filamentous green algae and bluegreen algae). The findings are consistent with ecological theories that describe communities as the unique production of their etiologies. The implications of this to environmental toxicology are that almost all environmental events leave lasting effects, whether or not they have observed them.

  5. Irritable bowel syndrome: a test of the colonic hyperalgesia hypothesis.

    PubMed

    Latimer, P; Campbell, D; Latimer, M; Sarna, S; Daniel, E; Waterfall, W

    1979-09-01

    This study tested the hypothesis that, patients with irritable bowel syndrome (IBS), there is a primary hyperalgesia of the colon. Previous work, which examined these patients and normals, has not included subjects who provide a control for relevant psychological characteristics. We compared ratings of pain, following varying degrees of distension of the sigmoid colon, in normals, patients with IBS, and patients who were psychologically disturbed but without bowel symptoms. Psychological characteristics were assessed by a psychiatric interview and psychometric inventories; response to distension was tested by placing a tube in the rectosigmoid colon and successively inflating a nd deflating a balloon at its tip at 10 cm3 increments up to 50 cm3. Ratings of pain were recorded at each volume. The results indicated that the two patient groups were psychologically similar and both were more disturbed than normals. A linear relation was found between reports of pain and volume of distension in all three groups. There were no significant differences between the proportions of subjects experiencing pain in each group or the average of the ratings. There were no significant associations between the pain ratings and measures of anxiety, depression, neuroticism, and extraversion. The data do not support the hypothesis that colonic hyperalgesia is an important contributory factor in the etiology of the irritable bowel syndrome. PMID:537039

  6. Physiology of natriuretic peptides: The volume overload hypothesis revisited

    PubMed Central

    Arjamaa, Olli

    2014-01-01

    The discovery of the natriuretic peptide system in the early 1980s aroused great interest among clinical cardiologists. The heart was not a mechanical pump alone, but also an endocrine organ that had powerful effects on blood circulation. Natriuretic peptides caused both natriuresis and diuresis, and they responded to a volume overload which caused either stretch or pressure on the heart. As a result, the findings led to the conclusion that the human body had a hormone with effects similar to those of a drug which treats high blood pressure. Later, it became evident that the volume contraction was fortified by extrarenal plasma shift. Here, a hypothesis is presented in which the role of natriuretic peptides is to regulate oxygen transport as the volume contraction leads to hemoconcentration with an increased oxygen-carrying capacity. Wall stress, either chemical or mechanical, changes the oxygen gradient of the myocardium and affects the diffusion of oxygen within a myocyte. In support of this hypothesis, hypoxia-response elements have been found in both the atrial natriuretic peptide and the brain natriuretic peptide genes. PMID:24527182

  7. Reading ability and computer-related attitudes among African American graduate students.

    PubMed

    Collins, Kathleen M T; Onwuegbuzie, Anthony J; Jiao, Qun G

    2008-06-01

    This study examined the degree that African American graduate students' reading abilities predict their attitudes toward computers and the educational use of the Internet. A canonical correlation analysis revealed that students with the lowest levels of reading ability tended to report the least computer confidence, least positive attitudes regarding computer liking, and least positive attitudes toward the educational use of the Internet. Findings of the study provide support for the hypothesis that reading ability differentially impacts African American graduate students' computer-related attitudes. The findings also suggest that reading ability may impede African American students' acquisition of computer and Internet skills and may negatively impact their achievement levels in graduate courses requiring computer-based skills. PMID:18537506

  8. Ontological confusions but not mentalizing abilities predict religious belief, paranormal belief, and belief in supernatural purpose.

    PubMed

    Lindeman, Marjaana; Svedholm-Häkkinen, Annika M; Lipsanen, Jari

    2015-01-01

    The current research tested the hypothesis that the abilities for understanding other people's minds give rise to the cognitive biases that underlie supernatural beliefs. We used structural equation modeling (N=2789) to determine the roles of various mentalizing tendencies, namely self-reported affective and cognitive empathy (i.e., mind reading), actual cognitive and affective empathic abilities, hyper-empathizing, and two cognitive biases (core ontological confusions and promiscuous teleology) in giving rise to supernatural beliefs. Support for a path from mentalizing abilities through cognitive biases to supernatural beliefs was weak. The relationships of mentalizing abilities with supernatural beliefs were also weak, and these relationships were not substantially mediated by cognitive biases. Core ontological confusions emerged as the best predictor, while promiscuous teleology predicted only a small proportion of variance. The results were similar for religious beliefs, paranormal beliefs, and for belief in supernatural purpose. PMID:25460380

  9. The "Eye Avoidance" Hypothesis of Autism Face Processing

    ERIC Educational Resources Information Center

    Tanaka, James W.; Sung, Andrew

    2016-01-01

    Although a growing body of research indicates that children with autism spectrum disorder (ASD) exhibit selective deficits in their ability to recognize facial identities and expressions, the source of their face impairment is, as yet, undetermined. In this paper, we consider three possible accounts of the autism face deficit: (1) the holistic…

  10. Phonological Representations in Deaf Children: Rethinking the "Functional Equivalence" Hypothesis

    ERIC Educational Resources Information Center

    McQuarrie, Lynn; Parrila, Rauno

    2009-01-01

    The sources of knowledge that individuals use to make similarity judgments between words are thought to tap underlying phonological representations. We examined the effects of perceptual similarity between stimuli on deaf children's ability to make judgments about the phonological similarity between words at 3 levels of linguistic structure…

  11. Testing the Indifferentiation Hypothesis during Childhood, Adolescence, and Adulthood

    ERIC Educational Resources Information Center

    Juan-Espinosa, Manuel; Cuevas, Lara; Escorial, Sergio; Garcia, Luis F.

    2006-01-01

    The general ("g") factor is the most general and relevant cognitive ability. This factor is considered to be one of the most important predictors of academic achievement and of many other socially relevant behavioral outcomes. In the last decades, many researchers have investigated the possible changes in the relevance of the "g" factor from…

  12. Graphic Abilities in Relation to Mathematical and Scientific Ability in Adolescents

    ERIC Educational Resources Information Center

    Stavridou, Fotini; Kakana, Domna

    2008-01-01

    Background: The study investigated a small range of cognitive abilities, related to visual-spatial intelligence, in adolescents. This specific range of cognitive abilities was termed "graphic abilities" and defined as a range of abilities to visualise and think in three dimensions, originating in the domain of visual-spatial intelligence, and…

  13. Developing and Demonstrating Knowledge: Ability and Non-Ability Determinants of Learning and Performance

    ERIC Educational Resources Information Center

    Beier, Margaret E.; Campbell, Madeline; Crook, Amy E.

    2010-01-01

    Ability and non-ability traits were examined as predictors of learning, operationalized as the development of knowledge structure accuracy, and exam performance in a semester-long course. As predicted by investment theories of intellectual development, both cognitive ability and non-ability traits were important determinants of learning and exam…

  14. Personality and problem-solving performance explain competitive ability in the wild

    PubMed Central

    Cole, Ella F.; Quinn, John L.

    2012-01-01

    Competitive ability is a major determinant of fitness, but why individuals vary so much in their competitiveness remains only partially understood. One increasingly prevalent view is that realized competitive ability varies because it represents alternative strategies that arise because of the costs associated with competitiveness. Here we use a population of great tits (Parus major) to explore whether individual differences in competitive ability when foraging can be explained by two traits that have previously been linked to alternative behavioural strategies: the personality trait ‘exploration behaviour’ and a simple cognitive trait, ‘innovative problem-solving performance’. We assayed these traits under standardized conditions in captivity and then measured competitive ability at feeders with restricted access in the wild. Competitive ability was repeatable within individual males across days and correlated positively with exploration behaviour, representing the first such demonstration of a link between a personality trait and both competitive ability and food intake in the wild. Competitive ability was also simultaneously negatively correlated with problem-solving performance; individuals who were poor competitors were good at problem-solving. Rather than being the result of variation in ‘individual quality’, our results support the hypothesis that individual variation in competitive ability can be explained by alternative behavioural strategies. PMID:21937498

  15. Sex differences in spatial abilities of medical graduates entering residency programs.

    PubMed

    Langlois, Jean; Wells, Georges A; Lecourtois, Marc; Bergeron, Germain; Yetisir, Elizabeth; Martin, Marcel

    2013-01-01

    Sex differences favoring males in spatial abilities have been known by cognitive psychologists for more than half a century. Spatial abilities have been related to three-dimensional anatomy knowledge and the performance in technical skills. The issue of sex differences in spatial abilities has not been addressed formally in the medical field. The objective of this study was to test an a priori hypothesis of sex differences in spatial abilities in a group of medical graduates entering their residency programs over a five-year period. A cohort of 214 medical graduates entering their specialist residency training programs was enrolled in a prospective study. Spatial abilities were measured with a redrawn Vandenberg and Kuse Mental Rotations Tests in two (MRTA) and three (MRTC) dimensions. Sex differences favoring males were identified in 131 (61.2%) female and 83 (38.8%) male medical graduates with the median (Q1, Q3) MRTA score [12 (8, 14) vs. 15 (12, 18), respectively; P < 0.0001] and MRTC score [7 (5, 9) vs. 9 (7, 12), respectively; P < 0.0001]. Sex differences in spatial abilities favoring males were demonstrated in the field of medical education, in a group of medical graduates entering their residency programs in a five-year experiment. Caution should be exerted in applying our group finding to individuals because a particular female may have higher spatial abilities and a particular male may have lower spatial abilities. PMID:23554271

  16. Testing the activitystat hypothesis: a randomised controlled trial protocol

    PubMed Central

    2012-01-01

    Background The activitystat hypothesis proposes that when physical activity or energy expenditure is increased or decreased in one domain, there will be a compensatory change in another domain to maintain an overall, stable level of physical activity or energy expenditure. To date, there has been no experimental study primarily designed to test the activitystat hypothesis in adults. The aim of this trial is to determine the effect of two different imposed exercise loads on total daily energy expenditure and physical activity levels. Methods This study will be a randomised, multi-arm, parallel controlled trial. Insufficiently active adults (as determined by the Active Australia survey) aged 18–60 years old will be recruited for this study (n=146). Participants must also satisfy the Sports Medicine Australia Pre-Exercise Screening System and must weigh less than 150 kg. Participants will be randomly assigned to one of three groups using a computer-generated allocation sequence. Participants in the Moderate exercise group will receive an additional 150 minutes of moderate to vigorous physical activity per week for six weeks, and those in the Extensive exercise group will receive an additional 300 minutes of moderate to vigorous physical activity per week for six weeks. Exercise targets will be accumulated through both group and individual exercise sessions monitored by heart rate telemetry. Control participants will not be given any instructions regarding lifestyle. The primary outcome measures are activity energy expenditure (doubly labeled water) and physical activity (accelerometry). Secondary measures will include resting metabolic rate via indirect calorimetry, use of time, maximal oxygen consumption and several anthropometric and physiological measures. Outcome measures will be conducted at baseline (zero weeks), mid- and end-intervention (three and six weeks) with three (12 weeks) and six month (24 week) follow-up. All assessors will be blinded to group

  17. Rhythm perception and production predict reading abilities in developmental dyslexia.

    PubMed

    Flaugnacco, Elena; Lopez, Luisa; Terribili, Chiara; Zoia, Stefania; Buda, Sonia; Tilli, Sara; Monasta, Lorenzo; Montico, Marcella; Sila, Alessandra; Ronfani, Luca; Schön, Daniele

    2014-01-01

    Rhythm organizes events in time and plays a major role in music, but also in the phonology and prosody of a language. Interestingly, children with developmental dyslexia-a learning disability that affects reading acquisition despite normal intelligence and adequate education-have a poor rhythmic perception. It has been suggested that an accurate perception of rhythmical/metrical structure, that requires accurate perception of rise time, may be critical for phonological development and subsequent literacy. This hypothesis is mostly based on results showing a high degree of correlation between phonological awareness and metrical skills, using a very specific metrical task. We present new findings from the analysis of a sample of 48 children with a diagnosis of dyslexia, without comorbidities. These children were assessed with neuropsychological tests, as well as specifically-devised psychoacoustic and musical tasks mostly testing temporal abilities. Associations were tested by multivariate analyses including data mining strategies, correlations and most importantly logistic regressions to understand to what extent the different auditory and musical skills can be a robust predictor of reading and phonological skills. Results show a strong link between several temporal skills and phonological and reading abilities. These findings are discussed in the framework of the neuroscience literature comparing music and language processing, with a particular interest in the links between rhythm processing in music and language. PMID:24926248

  18. Development of Gaze Following Abilities in Wolves (Canis Lupus)

    PubMed Central

    Range, Friederike; Virányi, Zsófia

    2011-01-01

    The ability to coordinate with others' head and eye orientation to look in the same direction is considered a key step towards an understanding of others mental states like attention and intention. Here, we investigated the ontogeny and habituation patterns of gaze following into distant space and behind barriers in nine hand-raised wolves. We found that these wolves could use conspecific as well as human gaze cues even in the barrier task, which is thought to be more cognitively advanced than gazing into distant space. Moreover, while gaze following into distant space was already present at the age of 14 weeks and subjects did not habituate to repeated cues, gazing around a barrier developed considerably later and animals quickly habituated, supporting the hypothesis that different cognitive mechanisms may underlie the two gaze following modalities. More importantly, this study demonstrated that following another individuals' gaze around a barrier is not restricted to primates and corvids but is also present in canines, with remarkable between-group similarities in the ontogeny of this behaviour. This sheds new light on the evolutionary origins of and selective pressures on gaze following abilities as well as on the sensitivity of domestic dogs towards human communicative cues. PMID:21373192

  19. Rhythm perception and production predict reading abilities in developmental dyslexia

    PubMed Central

    Flaugnacco, Elena; Lopez, Luisa; Terribili, Chiara; Zoia, Stefania; Buda, Sonia; Tilli, Sara; Monasta, Lorenzo; Montico, Marcella; Sila, Alessandra; Ronfani, Luca; Schön, Daniele

    2014-01-01

    Rhythm organizes events in time and plays a major role in music, but also in the phonology and prosody of a language. Interestingly, children with developmental dyslexia—a learning disability that affects reading acquisition despite normal intelligence and adequate education—have a poor rhythmic perception. It has been suggested that an accurate perception of rhythmical/metrical structure, that requires accurate perception of rise time, may be critical for phonological development and subsequent literacy. This hypothesis is mostly based on results showing a high degree of correlation between phonological awareness and metrical skills, using a very specific metrical task. We present new findings from the analysis of a sample of 48 children with a diagnosis of dyslexia, without comorbidities. These children were assessed with neuropsychological tests, as well as specifically-devised psychoacoustic and musical tasks mostly testing temporal abilities. Associations were tested by multivariate analyses including data mining strategies, correlations and most importantly logistic regressions to understand to what extent the different auditory and musical skills can be a robust predictor of reading and phonological skills. Results show a strong link between several temporal skills and phonological and reading abilities. These findings are discussed in the framework of the neuroscience literature comparing music and language processing, with a particular interest in the links between rhythm processing in music and language. PMID:24926248

  20. Basic Timing Abilities Stay Intact in Patients with Musician's Dystonia

    PubMed Central

    van der Steen, M. C.; van Vugt, Floris T.; Keller, Peter E.; Altenmüller, Eckart

    2014-01-01

    Task-specific focal dystonia is a movement disorder that is characterized by the loss of voluntary motor control in extensively trained movements. Musician's dystonia is a type of task-specific dystonia that is elicited in professional musicians during instrumental playing. The disorder has been associated with deficits in timing. In order to test the hypothesis that basic timing abilities are affected by musician's dystonia, we investigated a group of patients (N = 15) and a matched control group (N = 15) on a battery of sensory and sensorimotor synchronization tasks. Results did not show any deficits in auditory-motor processing for patients relative to controls. Both groups benefited from a pacing sequence that adapted to their timing (in a sensorimotor synchronization task at a stable tempo). In a purely perceptual task, both groups were able to detect a misaligned metronome when it was late rather than early relative to a musical beat. Overall, the results suggest that basic timing abilities stay intact in patients with musician's dystonia. This supports the idea that musician's dystonia is a highly task-specific movement disorder in which patients are mostly impaired in tasks closely related to the demands of actually playing their instrument. PMID:24667273

  1. Basic timing abilities stay intact in patients with musician's dystonia.

    PubMed

    van der Steen, M C; van Vugt, Floris T; Keller, Peter E; Altenmüller, Eckart

    2014-01-01

    Task-specific focal dystonia is a movement disorder that is characterized by the loss of voluntary motor control in extensively trained movements. Musician's dystonia is a type of task-specific dystonia that is elicited in professional musicians during instrumental playing. The disorder has been associated with deficits in timing. In order to test the hypothesis that basic timing abilities are affected by musician's dystonia, we investigated a group of patients (N = 15) and a matched control group (N = 15) on a battery of sensory and sensorimotor synchronization tasks. Results did not show any deficits in auditory-motor processing for patients relative to controls. Both groups benefited from a pacing sequence that adapted to their timing (in a sensorimotor synchronization task at a stable tempo). In a purely perceptual task, both groups were able to detect a misaligned metronome when it was late rather than early relative to a musical beat. Overall, the results suggest that basic timing abilities stay intact in patients with musician's dystonia. This supports the idea that musician's dystonia is a highly task-specific movement disorder in which patients are mostly impaired in tasks closely related to the demands of actually playing their instrument. PMID:24667273

  2. Invasive Plants and Enemy Release: Evolution of Trait Means and Trait Correlations in Ulex europaeus

    PubMed Central

    Hornoy, Benjamin; Tarayre, Michèle; Hervé, Maxime; Gigord, Luc; Atlan, Anne

    2011-01-01

    Several hypotheses that attempt to explain invasive processes are based on the fact that plants have been introduced without their natural enemies. Among them, the EICA (Evolution of Increased Competitive Ability) hypothesis is the most influential. It states that, due to enemy release, exotic plants evolve a shift in resource allocation from defence to reproduction or growth. In the native range of the invasive species Ulex europaeus, traits involved in reproduction and growth have been shown to be highly variable and genetically correlated. Thus, in order to explore the joint evolution of life history traits and susceptibility to seed predation in this species, we investigated changes in both trait means and trait correlations. To do so, we compared plants from native and invaded regions grown in a common garden. According to the expectations of the EICA hypothesis, we observed an increase in seedling height. However, there was little change in other trait means. By contrast, correlations exhibited a clear pattern: the correlations between life history traits and infestation rate by seed predators were always weaker in the invaded range than in the native range. In U. europaeus, the role of enemy release in shaping life history traits thus appeared to imply trait correlations rather than trait means. In the invaded regions studied, the correlations involving infestation rates and key life history traits such as flowering phenology, growth and pod density were reduced, enabling more independent evolution of these key traits and potentially facilitating local adaptation to a wide range of environments. These results led us to hypothesise that a relaxation of genetic correlations may be implied in the expansion of invasive species. PMID:22022588

  3. Evolution of Motor Control: From Reflexes and Motor Programs to the Equilibrium-Point Hypothesis

    PubMed Central

    Latash, Mark L.

    2009-01-01

    This brief review analyzes the evolution of motor control theories along two lines that emphasize active (motor programs) and reactive (reflexes) features of voluntary movements. It suggests that the only contemporary hypothesis that integrates both approaches in a fruitful way is the equilibrium-point hypothesis. Physical, physiological, and behavioral foundations of the EP-hypothesis are considered as well as relations between the EP-hypothesis and the recent developments of the notion of motor synergies. The paper ends with a brief review of the criticisms of the EP-hypothesis and challenges that the hypothesis faces at this time. PMID:19823595

  4. A network approach in analysis of the matching hypothesis

    NASA Astrophysics Data System (ADS)

    Jia, Tao; Spivey, Robert; Korniss, Gyorgy; Szymanski, Boleslaw

    2014-03-01

    The matching hypothesis in social psychology claimed that people are more likely to form a committed relationship with someone who is equally attractive. This phenomenon can be well interpreted by the principle of homophily that people are apt to get in touch with others similar to them. Yet, social experiments indicate that people in general tend to prefer more attractive individuals regardless of their own attractiveness. Here study the stochastic matching process for different underlying networks and different attractiveness distributions. We showed that the correlation of attractiveness within couples could purely due to the limited number of acquaintance each person has and such correlation decreases as the network becomes more sparse. We also analyzed the effect of the degree distribution and the attractiveness on the number of individuals that can not find their partners. This work is supported by ARL NS-CTA, ARO, and ONR.

  5. Southwest U. S. -East Antarctic (SWEAT) connection: A hypothesis

    SciTech Connect

    Moores, E.M. )

    1991-05-01

    A hypothesis for a late Precambrian fit of western North America with the Australia-Antarctic shield region permits the extension of many features through Antarctica and into other parts of Gondwana. Specifically, the Grenville orogen may extend around the coast of East Antarctica into India and Australia. The Wopmay orogen of northwest Canada may extend through eastern Australia into Antarctica and thence beneath the ice to connect with the Yavapai-Mazatzal orogens of the southwestern US. The ophiolitic belt of the latter may extend into East Antarctica. Counterparts of the Precambrian-Paleozoic sedimentary rocks along the US Cordilleran miogeocline may be present in the Transantarctic Mountains. Orogenic belt boundaries provide useful piercing points for Precambrian continental reconstructions. The model implies that Gondwana and Laurentia rifted away from each other on one margin and collided some 300 m.y. later on their opposite margins to from the Appalachians.

  6. Brain-derived neurotrophic factor: the neurotrophin hypothesis of psychopathology.

    PubMed

    Stein, Dan J; Daniels, Willie M U; Savitz, Jonathan; Harvey, Brian H

    2008-11-01

    While monoaminergic hypotheses of psychopathology remain popular, there has been growing interest in the role of neurotrophins in neuropsychiatric disorders. Basic laboratory work has documented the importance of neurotrophins in neuronal survival and synaptic plasticity, and a range of clinical studies has provided analogous evidence of their role in neuropathology. Work on gene variants in brain-derived neurotrophic factor, and associated changes in structural and function brain imaging, have further contributed to our understanding of this area. Much remains to be done to delineate fully the relevant mechanisms by which brain-derived neurotrophic factor and other neurotrophins contribute to psychopathology, and to develop targeted therapeutic interventions. Nevertheless, the neurotrophin hypothesis has already given impetus to a range of valuable research. PMID:19037180

  7. Network Dysfunction in Alzheimer's Disease: Refining the Disconnection Hypothesis

    PubMed Central

    Brier, Matthew R.; Thomas, Jewell B.

    2014-01-01

    Abstract Much effort in recent years has focused on understanding the effects of Alzheimer's disease (AD) on neural function. This effort has resulted in an enormous number of papers describing different facets of the functional derangement seen in AD. A particularly important tool for these investigations has been resting-state functional connectivity. Attempts to comprehensively synthesize resting-state functional connectivity results have focused on the potential utility of functional connectivity as a biomarker for disease risk, disease staging, or prognosis. While these are all appropriate uses of this technique, the purpose of this review is to examine how functional connectivity disruptions inform our understanding of AD pathophysiology. Here, we examine the rationale and methodological considerations behind functional connectivity studies and then provide a critical review of the existing literature. In conclusion, we propose a hypothesis regarding the development and spread of functional connectivity deficits seen in AD. PMID:24796856

  8. Quantization of Prior Probabilities for Collaborative Distributed Hypothesis Testing

    NASA Astrophysics Data System (ADS)

    Rhim, Joong Bum; Varshney, Lav R.; Goyal, Vivek K.

    2012-09-01

    This paper studies the quantization of prior probabilities, drawn from an ensemble, for distributed detection and data fusion. Design and performance equivalences between a team of N agents tied by a fixed fusion rule and a more powerful single agent are obtained. Effects of identical quantization and diverse quantization are compared. Consideration of perceived common risk enables agents using diverse quantizers to collaborate in hypothesis testing, and it is proven that the minimum mean Bayes risk error is achieved by diverse quantization. The comparison shows that optimal diverse quantization with K cells per quantizer performs as well as optimal identical quantization with N(K-1)+1 cells per quantizer. Similar results are obtained for maximum Bayes risk error as the distortion criterion.

  9. Imaging of Ventricular Fibrillation and Defibrillation: The Virtual Electrode Hypothesis

    PubMed Central

    Boukens, Bastiaan J.; Gutbrod, Sarah R.; Efimov, Igor R.

    2016-01-01

    Ventricular fibrillation is the major underlying cause of sudden cardiac death. Understanding the complex activation patterns that give rise to ventricular fibrillation requires high resolution mapping of localized activation. The use of multi-electrode mapping unraveled re-entrant activation patterns that underlie ventricular fibrillation. However, optical mapping contributed critically to understanding the mechanism of defibrillation, where multi-electrode recordings could not measure activation patterns during and immediately after a shock. In addition, optical mapping visualizes the virtual electrodes that are generated during stimulation and defibrillation pulses, which contributed to the formulation of the virtual electrode hypothesis. The generation of virtual electrode induced phase singularities during defibrillation is arrhythmogenic and may lead to the induction of fibrillation subsequent to defibrillation. Defibrillating with low energy may circumvent this problem. Therefore, the current challenge is to use the knowledge provided by optical mapping to develop a low energy approach of defibrillation, which may lead to more successful defibrillation. PMID:26238060

  10. Prefrontal Cortical Opioids and Dysregulated Motivation: A Network Hypothesis.

    PubMed

    Baldo, Brian A

    2016-06-01

    Loss of inhibitory control over appetitively motivated behavior occurs in multiple psychiatric disorders, including drug abuse, behavioral addictions, and eating disorders with binge features. In this opinion article, novel actions of μ-opioid peptides in the prefrontal cortex (PFC) that could contribute to inhibitory control deficits will be discussed. Evidence has accrued to suggest that excessive intra-PFC μ-opioid receptor (μ-OR) signaling alters the PFC response to excitatory drive, resulting in supernormal and incoherent recruitment of multiple PFC output pathways. Affected pathways include functionally opposed PFC→hypothalamus 'appetitive driver' and PFC→striatum 'appetitive limiter' projections. This network perturbation engenders disorganized, impulsive appetitive responses. Evidence supporting this hypothesis from human imaging and animal studies will be discussed, and combinatorial drug treatments targeting μ-ORs and specific PFC subcortical targets will be explored. PMID:27233653

  11. Neurobiological hypothesis of color appearance and hue perception

    PubMed Central

    Schmidt, Brian P.; Neitz, Maureen; Neitz, Jay

    2014-01-01

    DeValois and DeValois (1993) showed that to explain hue appearance, S-cone signals have to be combined with M vs. L opponent signals in two different ways to produce red-green and yellow-blue axes respectively. Recently, it has been shown that color appearance is normal for individuals with genetic mutations that block S-cone input to blue-on ganglion cells. This is inconsistent with the DeValois hypothesis in which S-opponent konio-geniculate signals are combined with L−M signals at a 3rd processing stage in cortex. Instead, here we show that color appearance, including individual differences never explained before, are predicted by a model in which S-cone signals are combined with L vs. M signals in the outer retina. PMID:24695170

  12. Structural evidence for the rare tautomer hypothesis of spontaneous mutagenesis

    SciTech Connect

    Wang, Weina; Hellinga, Homme W.; Beese, Lorena S.

    2012-05-10

    Even though high-fidelity polymerases copy DNA with remarkable accuracy, some base-pair mismatches are incorporated at low frequency, leading to spontaneous mutagenesis. Using high-resolution X-ray crystallographic analysis of a DNA polymerase that catalyzes replication in crystals, we observe that a C {center_dot} A mismatch can mimic the shape of cognate base pairs at the site of incorporation. This shape mimicry enables the mismatch to evade the error detection mechanisms of the polymerase, which would normally either prevent mismatch incorporation or promote its nucleolytic excision. Movement of a single proton on one of the mismatched bases alters the hydrogen-bonding pattern such that a base pair forms with an overall shape that is virtually indistinguishable from a canonical, Watson-Crick base pair in double-stranded DNA. These observations provide structural evidence for the rare tautomer hypothesis of spontaneous mutagenesis, a long-standing concept that has been difficult to demonstrate directly.

  13. An especial skill: Support for a learned parameters hypothesis.

    PubMed

    Breslin, Gavin; Hodges, Nicola J; Kennedy, Rodney; Hanlon, Michael; Williams, A Mark

    2010-05-01

    We tested the 'learned parameters' hypothesis as an explanation of the 'especial skill effect'. Outcome attainment and movement kinematics were recorded for 10 expert and 10 novice players performing basketball free-throw shots at five distances (11-19 ft) with a regular and heavy weight basketball. As predicted, experts performed better than expected relative to the regression equation at the 15 ft, free-throw line with the regular basketball, supporting the 'especial skill effect'. This effect was not present for the experts when shooting with the heavy ball. Novices did not show an advantage at the free-throw line when performing with either ball. Although the outcome attainment scores support the 'learned parameters' hypotheses, kinematic analysis failed to identify differences in the movement pattern for the especial skill, suggesting that these skills (i.e., shooting at different distances) are not governed by separate motor programs. PMID:20045100

  14. An Algorithm for Testing the Efficient Market Hypothesis

    PubMed Central

    Boboc, Ioana-Andreea; Dinică, Mihai-Cristian

    2013-01-01

    The objective of this research is to examine the efficiency of EUR/USD market through the application of a trading system. The system uses a genetic algorithm based on technical analysis indicators such as Exponential Moving Average (EMA), Moving Average Convergence Divergence (MACD), Relative Strength Index (RSI) and Filter that gives buying and selling recommendations to investors. The algorithm optimizes the strategies by dynamically searching for parameters that improve profitability in the training period. The best sets of rules are then applied on the testing period. The results show inconsistency in finding a set of trading rules that performs well in both periods. Strategies that achieve very good returns in the training period show difficulty in returning positive results in the testing period, this being consistent with the efficient market hypothesis (EMH). PMID:24205148

  15. Fast pulsars, compact stars, and the strange matter hypothesis

    SciTech Connect

    Weber, F.; Glendenning, N.K.

    1993-03-17

    Part one of this paper deals with the recent finding of the possible existence of a mixed phase of baryon matter and quark matter inside neutron stars. In part two we review the theoretically determined minimum rotational periods of neutron stars, which serve to distinguish between pulsars that can be understood as rotating neutron stars and those that can not. Likely candidates for the latter are hypothetical strange stars. Their mass-radius relationship is discussed in the last part. It is pointed out that strange stars with a nuclear crust can give rise to the observed phenomena of pulsar glitches, thus passing the only astrophysical test of the strange-matter hypothesis existing to date.

  16. The hypothesis of superluminal neutrinos: Comparing OPERA with other data

    NASA Astrophysics Data System (ADS)

    Drago, A.; Masina, I.; Pagliara, G.; Tripiccione, R.

    2012-01-01

    The OPERA Collaboration reported evidence for muonic neutrinos traveling slightly faster than light in vacuum. While waiting further checks from the experimental community, here we aim at exploring some theoretical consequences of the hypothesis that muonic neutrinos are superluminal, considering in particular the tachyonic and the Coleman-Glashow cases. We show that a tachyonic interpretation is not only hardly reconciled with OPERA data on energy dependence, but that it clashes with neutrino production from pion and with neutrino oscillations. A Coleman-Glashow superluminal neutrino beam would also have problems with pion decay kinematics for the OPERA setup; it could be easily reconciled with SN1987a data, but then it would be very problematic to account for neutrino oscillations.

  17. Publication selection in health policy research: the winner's curse hypothesis.

    PubMed

    Costa-Font, Joan; McGuire, Alistair; Stanley, Tom

    2013-01-01

    There is a widely discussed problem of publication bias in medical and health services research. Where quantitative effects form the basis of a publication a 'winner's curse' curse may apply. This phenomenon may occur as prospective authors of research papers compete by reporting 'more extreme and spectacular results' in order to increase the chances of their paper being accepted for publication. This paper examines this phenomenon using quantitative findings on income and price elasticities as reported in health economics research. We find robust statistical evidence that higher-impact journals preferentially report larger empirical estimates of these elasticities. That is, we find robust evidence of a winner's curse hypothesis contributing to the existence of publication bias found in both the income and the price elasticities of health care and drugs, as well as value of life research. PMID:23182564

  18. Cholinergic deficiency hypothesis in delirium: a synthesis of current evidence.

    PubMed

    Hshieh, Tammy T; Fong, Tamara G; Marcantonio, Edward R; Inouye, Sharon K

    2008-07-01

    Deficits in cholinergic function have been postulated to cause delirium and cognitive decline. This review examines current understanding of the cholinergic deficiency hypothesis in delirium by synthesizing evidence on potential pathophysiological pathways. Acetylcholine synthesis involves various precursors, enzymes, and receptors, and dysfunction in these components can lead to delirium. Insults to the brain, like ischemia and immunological stressors, can precipitously alter acetylcholine levels. Imbalances between cholinergic and other neurotransmitter pathways may result in delirium. Furthermore, genetic, enzymatic, and immunological overlaps exist between delirium and dementia related to the cholinergic pathway. Important areas for future research include identifying biomarkers, determining genetic contributions, and evaluating response to cholinergic drugs in delirium. Understanding how the cholinergic pathway relates to delirium may yield innovative approaches in the diagnosis, prevention, and treatment of this common, costly, and morbid condition. PMID:18693233

  19. Probiotic bacteria and biosurfactants for nosocomial infection control: a hypothesis.

    PubMed

    Falagas, M E; Makris, G C

    2009-04-01

    The adaptation of strict hygienic practices by healthcare personnel as well as the implementation of appropriate cleaning and disinfection measures form the basis of infection control policies. However, nosocomial infections constitute a considerable problem even in hospitals with meticulous infection control programmes. This should prompt biomedical researchers to evaluate the efficacy and safety of novel infection control measures. There is preliminary evidence that probiotic type micro-organisms may antagonise the growth of nosocomial pathogens on inanimate surfaces. We therefore propose the hypothesis that environmental probiotic organisms may represent a safe and effective intervention for infection control purposes. We suggest that probiotics or their products (biosurfactants), could be applied to patient care equipment, such as tubes or catheters, with the aim of decreasing colonisation of sites by nosocomial pathogens. This could potentially impede a central step in the pathogenesis of nosocomial infections. PMID:19201053

  20. Brain Evolution and Human Neuropsychology: The Inferential Brain Hypothesis

    PubMed Central

    Koscik, Timothy R.; Tranel, Daniel

    2013-01-01

    Collaboration between human neuropsychology and comparative neuroscience has generated invaluable contributions to our understanding of human brain evolution and function. Further cross-talk between these disciplines has the potential to continue to revolutionize these fields. Modern neuroimaging methods could be applied in a comparative context, yielding exciting new data with the potential of providing insight into brain evolution. Conversely, incorporating an evolutionary base into the theoretical perspectives from which we approach human neuropsychology could lead to novel hypotheses and testable predictions. In the spirit of these objectives, we present here a new theoretical proposal, the Inferential Brain Hypothesis, whereby the human brain is thought to be characterized by a shift from perceptual processing to inferential computation, particularly within the social realm. This shift is believed to be a driving force for the evolution of the large human cortex. PMID:22459075