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Sample records for hashi syedain explains

  1. The Mayer Hashi Large-Scale Program to Increase Use of Long-Acting Reversible Contraceptives and Permanent Methods in Bangladesh: Explaining the Disappointing Results. An Outcome and Process Evaluation

    PubMed Central

    Rahman, Mizanur; Haider, M Moinuddin; Curtis, Sian L; Lance, Peter M

    2016-01-01

    ABSTRACT Background: Bangladesh has achieved a low total fertility rate of 2.3. Two-thirds of currently married women of reproductive age (CMWRA) want to limit fertility, and many women achieve their desired fertility before age 30. The incidence of unintended pregnancy and pregnancy termination is high, however. Long-acting reversible contraceptives (LARCs), consisting of the intrauterine device and implant, and permanent methods (PM), including female sterilization and vasectomy, offer several advantages in this situation, but only 8% of CMWRA or 13% of method users use these methods. Program: The Mayer Hashi (MH) program (2009–2013) aimed to improve access to and the quality of LARC/PM services in 21 of the 64 districts in Bangladesh. It was grounded in the SEED (supply–enabling environment–demand) Programming Model. Supply improvements addressed provider knowledge and skills, system strengthening, and logistics. Creating an enabling environment involved holding workshops with local and community leaders, including religious leaders, to encourage them to help promote demand for LARCs and PMs and overcome cultural barriers. Demand promotion encompassed training of providers in counseling, distribution of behavior change communication materials in the community and in facilities, and community mobilization. Methods: We selected 6 MH program districts and 3 nonprogram districts to evaluate the program. We used a before–after and intervention–comparison design to measure the changes in key contraceptive behavior outcomes, and we used a difference-in-differences (DID) specification with comparison to the nonprogram districts to capture the impact of the program. In addition to the outcome evaluation, we considered intermediate indicators that measured the processes through which the interventions were expected to affect the use of LARCs and PMs. Results: The use of LARCs/PMs among CMWRA increased between 2010 and 2013 in both program (from 5.3% to 7.5%) and

  2. Astronomy Explained

    NASA Astrophysics Data System (ADS)

    North, Gerald

    Every year large numbers of people take up the study of astronomy, mostly at amateur level. There are plenty of elementary books on the market, full of colourful photographs, but lacking in proper explanations of how and why things are as they are. Many people eventually wish to go beyond the 'coffee-table book' stage and study this fascinating subject in greater depth. This book is written for them. In addition, many people sit for public examinations in this subject each year and this book is also intended to be of use to them. All the topics from the GCSE syllabus are covered here, with sample questions at the end of each chapter. Astronomy Explained provides a comprehensive treatment of the subject in more depth than is usually found in elementary works, and will be of interest to both amateur astronomers and students of astronomy.

  3. Explaining the Oxbridge Figures.

    ERIC Educational Resources Information Center

    Davies, Bronwyn; Harre, Rom

    1989-01-01

    Rejects sociobiological theories on female academic achievement and bases findings on social structure to explain why undergraduate women at Oxford University (England) achieve fewer first places and more second places in class honors. Bases theory on bipolarity of gender as an organizing principle of society. Claims that the double bind of social…

  4. Explaining Immigrant Naturalization.

    ERIC Educational Resources Information Center

    Yang, Philip Q.

    1994-01-01

    Proposes a broad analytical framework in the study of immigrant naturalization that incorporates an immigrant's individual characteristics with the larger social contexts in the country of origin and the country of destination to explain the likelihood of citizenship acquisition. Results testing of this framework show that such considerations are…

  5. Dendrite Model Explained

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Angie Jackman, a NASA project manager in microgravity research, explains a model of a dendrite to a visitor to the NASA exhibit at AirVenture 2000 sponsored by the Experimental Aircraft Association in Oshkosh, WI. The model depicts microscopic dendrites that grow as molten metals solidify. NASA sponsored three experiments aboard the Space Shuttle that used the microgravity environment to study the formation of large (1 to 4 mm) dendrites without Earth's gravity disrupting their growth. Three advanced follow-on experiments, managed by Jackman, are being developed for the International Space Station (ISS).

  6. Explaining embodied cognition results.

    PubMed

    Lakoff, George

    2012-10-01

    From the late 1950s until 1975, cognition was understood mainly as disembodied symbol manipulation in cognitive psychology, linguistics, artificial intelligence, and the nascent field of Cognitive Science. The idea of embodied cognition entered the field of Cognitive Linguistics at its beginning in 1975. Since then, cognitive linguists, working with neuroscientists, computer scientists, and experimental psychologists, have been developing a neural theory of thought and language (NTTL). Central to NTTL are the following ideas: (a) we think with our brains, that is, thought is physical and is carried out by functional neural circuitry; (b) what makes thought meaningful are the ways those neural circuits are connected to the body and characterize embodied experience; (c) so-called abstract ideas are embodied in this way as well, as is language. Experimental results in embodied cognition are seen not only as confirming NTTL but also explained via NTTL, mostly via the neural theory of conceptual metaphor. Left behind more than three decades ago is the old idea that cognition uses the abstract manipulation of disembodied symbols that are meaningless in themselves but that somehow constitute internal "representations of external reality" without serious mediation by the body and brain. This article uniquely explains the connections between embodied cognition results since that time and results from cognitive linguistics, experimental psychology, computational modeling, and neuroscience.

  7. Explaining moral religions.

    PubMed

    Baumard, Nicolas; Boyer, Pascal

    2013-06-01

    Moralizing religions, unlike religions with morally indifferent gods or spirits, appeared only recently in some (but not all) large-scale human societies. A crucial feature of these new religions is their emphasis on proportionality (between deeds and supernatural rewards, between sins and penance, and in the formulation of the Golden Rule, according to which one should treat others as one would like others to treat oneself). Cognitive science models that account for many properties of religion can be extended to these religions. Recent models of evolved dispositions for fairness in cooperation suggest that proportionality-based morality is highly intuitive to human beings. The cultural success of moralizing movements, secular or religious, could be explained based on proportionality.

  8. Explaining wartime rape.

    PubMed

    Gottschall, Jonathan

    2004-05-01

    In the years since the first reports of mass rapes in the Yugoslavian wars of secession and the genocidal massacres in Rwanda, feminist activists and scholars, human rights organizations, journalists, and social scientists have dedicated unprecedented efforts to document, explain, and seek solutions for the phenomenon of wartime rape. While contributors to this literature agree on much, there is no consensus on causal factors. This paper provides a brief overview of the literature on wartime rape in historical and ethnographical societies and a critical analysis of the four leading explanations for its root causes: the feminist theory, the cultural pathology theory, the strategic rape theory, and the biosocial theory. The paper concludes that the biosocial theory is the only one capable of bringing all the phenomena associated with wartime rape into a single explanatory context.

  9. Explaining Warm Coronal Loops

    NASA Technical Reports Server (NTRS)

    Klimchuk, James A.; Karpen, Judy T.; Patsourakos, Spiros

    2008-01-01

    One of the great mysteries of coronal physics that has come to light in the last few years is the discovery that warn (- 1 INK) coronal loops are much denser than expected for quasi-static equilibrium. Both the excess densities and relatively long lifetimes of the loops can be explained with bundles of unresolved strands that are heated impulsively to very high temperatures. Since neighboring strands are at different stages of cooling, the composite loop bundle is multi-thermal, with the distribution of temperatures depending on the details of the "nanoflare storm." Emission hotter than 2 MK is predicted, but it is not clear that such emission is always observed. We consider two possible explanations for the existence of over-dense warm loops without corresponding hot emission: (1) loops are bundles of nanoflare heated strands, but a significant fraction of the nanoflare energy takes the form of a nonthermal electron beam rather then direct plasma heating; (2) loops are bundles of strands that undergo thermal nonequilibrium that results when steady heating is sufficiently concentrated near the footpoints. We present numerical hydro simulations of both of these possibilities and explore the observational consequences, including the production of hard X-ray emission and absorption by cool material in the corona.

  10. Explaining climate danger

    NASA Astrophysics Data System (ADS)

    Oreskes, N.

    2016-12-01

    The idea of `managing planet Earth' is traceable back at least to the 1970s. Recently, it has been reformulated in the idea of a "good Anthropocene": the idea that humans should and can try to manage our planet now that we have become a planetary force. Yet available evidence and experience suggests that our prior attempts to do so have been plagued by under-estimation of the scale of the problems and over-estimation of our capacities to address them. In any case, Earth is not at risk—our planet will survive despite what we do or fail to do. Global climate change, for example, is not a problem for the planet, it is a problem for us. As the UNFCCC articulated in the 1990s, climate change matters because it is dangerous. Yet many Americans still do not understand why this is the case. I suggest that scientists can profitably focus attention on explaining this danger—why climate represents a threat to our health, well-being, and lives—and on what kinds of steps can be taken to reduce the danger.

  11. Explaining gender segregation.

    PubMed

    Blackburn, Robert M; Browne, Jude; Brooks, Bradley; Jarman, Jennifer

    2002-12-01

    Occupational gender segregation--the tendency for women and men to work in different occupations--is an important feature of all societies, and particularly the wealthy industrialized ones. To understand this segregation, and to explain its significance, we need to distinguish between vertical segregation entailing inequality and horizontal segregation representing difference without inequality, with overall segregation being the resultant of these components. Three major theoretical approaches to understanding occupational gender segregation are examined: human capital/rational choice, patriarchy, and preference theories. All are found to be inadequate; they tend to confuse overall segregation with its vertical component, and each entails a number of other faults. It is generally assumed or implied that greater empowerment of women would reduce gender segregation. This is the reverse of what actually happens; in countries where the degree of women's empowerment is greater, the level of gender segregation is also greater. An alternative theoretical approach based on processes of social reproduction is shown to be more useful.

  12. Explaining Warm Coronal Loops

    NASA Technical Reports Server (NTRS)

    Klimchuk, James A.; Karpen, Judy T.; Patsourakos, Spiros

    2008-01-01

    One of the great mysteries of coronal physics that has come to light in the last few years is the discovery that warn (- 1 INK) coronal loops are much denser than expected for quasi-static equilibrium. Both the excess densities and relatively long lifetimes of the loops can be explained with bundles of unresolved strands that are heated impulsively to very high temperatures. Since neighboring strands are at different stages of cooling, the composite loop bundle is multi-thermal, with the distribution of temperatures depending on the details of the "nanoflare storm." Emission hotter than 2 MK is predicted, but it is not clear that such emission is always observed. We consider two possible explanations for the existence of over-dense warm loops without corresponding hot emission: (1) loops are bundles of nanoflare heated strands, but a significant fraction of the nanoflare energy takes the form of a nonthermal electron beam rather then direct plasma heating; (2) loops are bundles of strands that undergo thermal nonequilibrium that results when steady heating is sufficiently concentrated near the footpoints. We present numerical hydro simulations of both of these possibilities and explore the observational consequences, including the production of hard X-ray emission and absorption by cool material in the corona.

  13. Explaining Synthesized Software

    NASA Technical Reports Server (NTRS)

    VanBaalen, Jeffrey; Robinson, Peter; Lowry, Michael; Pressburger, Thomas; Lau, Sonie (Technical Monitor)

    1998-01-01

    Motivated by NASA's need for high-assurance software, NASA Ames' Amphion project has developed a generic program generation system based on deductive synthesis. Amphion has a number of advantages, such as the ability to develop a new synthesis system simply by writing a declarative domain theory. However, as a practical matter, the validation of the domain theory for such a system is problematic because the link between generated programs and the domain theory is complex. As a result, when generated programs do not behave as expected, it is difficult to isolate the cause, whether it be an incorrect problem specification or an error in the domain theory. This paper describes a tool we are developing that provides formal traceability between specifications and generated code for deductive synthesis systems. It is based on extensive instrumentation of the refutation-based theorem prover used to synthesize programs. It takes augmented proof structures and abstracts them to provide explanations of the relation between a specification, a domain theory, and synthesized code. In generating these explanations, the tool exploits the structure of Amphion domain theories, so the end user is not confronted with the intricacies of raw proof traces. This tool is crucial for the validation of domain theories as well as being important in everyday use of the code synthesis system. It plays an important role in validation because when generated programs exhibit incorrect behavior, it provides the links that can be traced to identify errors in specifications or domain theory. It plays an important role in the everyday use of the synthesis system by explaining to users what parts of a specification or of the domain theory contribute to what pieces of a generated program. Comments are inserted into the synthesized code that document these explanations.

  14. Jupiter's Gossamer Rings Explained.

    NASA Astrophysics Data System (ADS)

    Hamilton, D. P.

    2003-05-01

    Over the past several years, Galileo measurements and groundbased imaging have drastically improved our knowledge of Jupiter's faint ring system. We now recognize that the ring consists of four components: a main ring 7000km wide, whose inner edge blossoms into a vertically-extended halo, and a pair of more tenuous Gossamer rings, one associated with each of the small moons Thebe and Amalthea. When viewed edge on, the Gossamer rings appear as diaphanous disks whose thicknesses agree with the vertical excursions of the inclined satellites from the equatorial plane. In addition, the brightness of each Gossamer ring drops off sharply outside the satellite orbits. These correlations allowed Burns etal (1999, Science, 284, 1146) to argue convincingly that the satellites act as sources of the dusty ring material. In addition, since most material is seen inside the orbits of the source satellites, an inwardly-acting dissipative force such as Poynting-Robertson drag is implicated. The most serious problem with this simple and elegant picture is that it is unable to explain the existence of a faint swath of material that extends half a jovian radius outward from Thebe. A key constraint is that this material has the same thickness as the rest of the Thebe ring. In this work, we identify the mechanism responsible for the outward extension: it is a shadow resonance, first investigated by Horanyi and Burns (1991, JGR, 96, 19283). When a dust grain enters Jupiter's shadow, photoelectric processes shut down and the grain's electric charge becomes more negative. The electromagnetic forces associated with the varying charge cause periodic oscillations in the orbital eccentricity and semimajor axis as the orbital pericenter precesses. This results in a ring which spreads both inward and outward of its source satellite while preserving its vertical thickness - just as is observed for the Thebe ring. Predictions of the model are: i) gaps of micron-sized material interior to Thebe and

  15. Your Radiologist Explains Nuclear Medicine

    MedlinePlus

    ... Sponsored by Image/Video Gallery Your Radiologist Explains Nuclear Medicine Transcript Welcome to Radiology Info dot org ... I’d like to talk to you about nuclear medicine. Nuclear medicine offers the potential to identify ...

  16. Your Radiologist Explains Nuclear Medicine

    MedlinePlus Videos and Cool Tools

    ... by Image/Video Gallery Your Radiologist Explains Nuclear Medicine Transcript Welcome to Radiology Info dot org Hello! ... d like to talk to you about nuclear medicine. Nuclear medicine offers the potential to identify disease ...

  17. Does market competition explain fairness?

    PubMed

    Descioli, Peter

    2013-02-01

    The target article by Baumard et al. uses their previous model of bargaining with outside options to explain fairness and other features of human sociality. This theory implies that fairness judgments are determined by supply and demand but humans often perceive prices (divisions of surplus) in competitive markets to be unfair.

  18. Explaining Errors in Children's Questions

    ERIC Educational Resources Information Center

    Rowland, Caroline F.

    2007-01-01

    The ability to explain the occurrence of errors in children's speech is an essential component of successful theories of language acquisition. The present study tested some generativist and constructivist predictions about error on the questions produced by ten English-learning children between 2 and 5 years of age. The analyses demonstrated that,…

  19. Explaining mirror-touch synesthesia.

    PubMed

    Ward, Jamie; Banissy, Michael J

    2015-01-01

    Mirror-touch synesthesia (MTS) is the conscious experience of tactile sensations induced by seeing someone else touched. This paper considers two different, although not mutually exclusive, theoretical explanations and, in the final section, considers the relation between MTS and other forms of synesthesia and also other kinds of vicarious perception (e.g., contagious yawning). The Threshold Theory explains MTS in terms of hyper-activity within a mirror system for touch and/or pain. This offers a good account for some of the evidence (e.g., from fMRI) but fails to explain the whole pattern (e.g., structural brain differences outside of this system; performance on some tests of social cognition). The Self-Other Theory explains MTS in terms of disturbances in the ability to distinguish the self from others. This can be construed in terms of over-extension of the bodily self in to others, or as difficulties in the control of body-based self-other representations. In this account, MTS is a symptom of a broader cognitive profile. We suggest this meets the criteria for synesthesia, despite the proximal causal mechanisms remaining largely unknown, and that the tendency to localize vicarious sensory experiences distinguishes it from other kinds of seemingly related phenomena (e.g., non-localized affective responses to observing pain).

  20. Explaining the Gender Wealth Gap

    PubMed Central

    Ruel, Erin; Hauser, Robert M.

    2013-01-01

    To assess and explain the United States’ gender wealth gap, we use the Wisconsin Longitudinal Study to examine wealth accumulated by a single cohort over 50 years by gender, by marital status, and limited to the respondents who are their family’s best financial reporters. We find large gender wealth gaps between currently married men and women, and never-married men and women. The never-married accumulate less wealth than the currently married, and there is a marital disruption cost to wealth accumulation. The status-attainment model shows the most power in explaining gender wealth gaps between these groups explaining about one-third to one-half of the gap, followed by the human-capital explanation. In other words, a lifetime of lower earnings for women translates into greatly reduced wealth accumulation. A gender wealth gap remains between married men and women after controlling for the full model that we speculate may be related to gender differences in investment strategies and selection effects. PMID:23264038

  1. Explaining the gender wealth gap.

    PubMed

    Ruel, Erin; Hauser, Robert M

    2013-08-01

    To assess and explain the United States' gender wealth gap, we use the Wisconsin Longitudinal Study to examine wealth accumulated by a single cohort over 50 years by gender, by marital status, and limited to the respondents who are their family's best financial reporters. We find large gender wealth gaps between currently married men and women, and between never-married men and women. The never-married accumulate less wealth than the currently married, and there is a marital disruption cost to wealth accumulation. The status-attainment model shows the most power in explaining gender wealth gaps between these groups explaining about one-third to one-half of the gap, followed by the human-capital explanation. In other words, a lifetime of lower earnings for women translates into greatly reduced wealth accumulation. After controlling for the full model, we find that a gender wealth gap remains between married men and women that we speculate may be related to gender differences in investment strategies and selection effects.

  2. Explaining the harmonic sequence paradox.

    PubMed

    Schmidt, Ulrich; Zimper, Alexander

    2012-05-01

    According to the harmonic sequence paradox, an expected utility decision maker's willingness to pay for a gamble whose expected payoffs evolve according to the harmonic series is finite if and only if his marginal utility of additional income becomes zero for rather low payoff levels. Since the assumption of zero marginal utility is implausible for finite payoff levels, expected utility theory - as well as its standard generalizations such as cumulative prospect theory - are apparently unable to explain a finite willingness to pay. This paper presents first an experimental study of the harmonic sequence paradox. Additionally, it demonstrates that the theoretical argument of the harmonic sequence paradox only applies to time-patient decision makers, whereas the paradox is easily avoided if time-impatience is introduced.

  3. Dark antiatoms can explain DAMA

    NASA Astrophysics Data System (ADS)

    Wallemacq, Quentin; Cudell, Jean-René

    2015-02-01

    We show that the existence of a sub-dominant form of dark matter, made of dark "antiatoms" of mass m~ 1 TeV and size dot a0~ 3 fm, can explain the results of direct detection experiments, with a positive signal in DAMA/NaI and DAMA/LIBRA and no signal in other experiments. The signal comes from the binding of the dark antiatoms to thallium, a dopant in DAMA, and is not present for the constituent atoms of other experiments. The dark antiatoms are made of two particles oppositely charged under a dark U(1) symmetry and can bind to terrestrial atoms because of a kinetic mixing between the photon and the massless dark photon, such that the dark particles acquire an electric millicharge ~ ± 5.10-4e. This millicharge enables them to bind to high-Z atoms via radiative capture, after they thermalize in terrestrial matter through elastic collisions.

  4. What explains consciousness? Or…What consciousness explains?

    PubMed

    Dulany, Donelson E

    2014-01-01

    In this invited commentary I focus on the topic addressed in three papers: De Sousa's (2013[1617]) Toward an Integrative Theory of Consciousness, a monograph with Parts 1 & 2, as well as commentaries by Pereira (2013a[59]) and Hirstein (2013[42]). All three are impressively scholarly and can stand-and shout-on their own. But theory of consciousness? My aim is to slice that topic into the two fundamentally different kinds of theories of consciousness, say what appears to be an ideology, out of behaviourism into cognitivism, now also influencing the quest for an "explanation of consciousness" in cognitive neuroscience. I will then say what can be expected given what we know of the complexity of brain structure, the richness of a conscious "vocabulary", and current technological limits of brain imaging. This will then turn to the strategy for examining "what consciousness explains"-metatheory, theories, mappings, and a methodology of competitive support, a methodology especially important where there are competing commitments. There are also increasingly common identifications of methodological bias in, along with failures to replicate, studies reporting unconscious controls in decision, social priming-as there have been in perception, learning, problem solving, etc. The literature critique has provided evidence taken as reducing, and in some cases eliminating, a role for conscious controls-a position consistent with that ideology out of behaviourism into cognitivism. It is an ideological position that fails to recognize the fundamental distinction between theoretical and metaphysical assertions.

  5. Dark antiatoms can explain DAMA

    SciTech Connect

    Wallemacq, Quentin; Cudell, Jean-René E-mail: jr.cudell@ulg.ac.be

    2015-02-01

    We show that the existence of a sub-dominant form of dark matter, made of dark ''antiatoms'' of mass m∼ 1 TeV and size a-dot {sub 0}∼ 3 fm, can explain the results of direct detection experiments, with a positive signal in DAMA/NaI and DAMA/LIBRA and no signal in other experiments. The signal comes from the binding of the dark antiatoms to thallium, a dopant in DAMA, and is not present for the constituent atoms of other experiments. The dark antiatoms are made of two particles oppositely charged under a dark U(1) symmetry and can bind to terrestrial atoms because of a kinetic mixing between the photon and the massless dark photon, such that the dark particles acquire an electric millicharge ∼ ± 5.10{sup −4}e. This millicharge enables them to bind to high-Z atoms via radiative capture, after they thermalize in terrestrial matter through elastic collisions.

  6. Explaining Mercury's peculiar magnetic field

    NASA Astrophysics Data System (ADS)

    Wicht, Johannes; Cao, Hao; Heyner, Daniel; Dietrich, Wieland; Christensen, Ulrich R.

    2014-05-01

    MESSENGER magnetometer data revealed that Mercury's magnetic field is not only particularly weak but also has a peculiar geometry. The MESSENGER team finds that the location of the magnetic equator always lies significantly north of the geographic equator, is largely independent of the distance to the planet, and also varies only weakly with longitude. The field is best described by an axial dipole that is offset to the north by about 20% of the planetary radius. In terms of classical Gauss coefficients, this translates into a low axial dipole component of g10= -190 nT but a relatively large axial quadrupole contribution that amounts to roughly 40% of this value. The axial octupole is also sizable while higher harmonic contributions are much weaker. Very remarkable is also the fact that the equatorial dipole contribution is very small, consistent with a dipole tilt below 0.8 degree, and this is also true for the other non-axisymmetic field contributions. We analyze several numerical dynamos concerning their capability of explaining Mercury's magnetic field. Classical schemes geared to model the geomagnetic field typically show a much weaker quadrupole component and thus a smaller offset. The onset only becomes larger when the dynamo operates in the multipolar regime at higher Rayleigh numbers. However, since the more complex dynamics generally promotes all higher multipole contributions the location of the magnetic equator varies strongly with longitude and distance to the planet. The situation improves when introducing a stably stratified outer layer in the dynamo region, representing either a rigid FeS layer or a sub-adiabatic core-mantle boundary heat flux. This layer filters out the higher harmonic contributions and the field not only becomes sufficiently weak but also assumes a Mercury like offset geometry during a few percent of the simulation time. To increase the likelihood for the offset configuration, the north-south symmetry must be permanently broken

  7. Explaining Constrains Causal Learning in Childhood

    ERIC Educational Resources Information Center

    Walker, Caren M.; Lombrozo, Tania; Williams, Joseph J.; Rafferty, Anna N.; Gopnik, Alison

    2017-01-01

    Three experiments investigate how self-generated explanation influences children's causal learning. Five-year-olds (N = 114) observed data consistent with two hypotheses and were prompted to explain or to report each observation. In Study 1, when making novel generalizations, explainers were more likely to favor the hypothesis that accounted for…

  8. Explaining Constrains Causal Learning in Childhood

    ERIC Educational Resources Information Center

    Walker, Caren M.; Lombrozo, Tania; Williams, Joseph J.; Rafferty, Anna N.; Gopnik, Alison

    2017-01-01

    Three experiments investigate how self-generated explanation influences children's causal learning. Five-year-olds (N = 114) observed data consistent with two hypotheses and were prompted to explain or to report each observation. In Study 1, when making novel generalizations, explainers were more likely to favor the hypothesis that accounted for…

  9. Explaining Constrains Causal Learning in Childhood.

    PubMed

    Walker, Caren M; Lombrozo, Tania; Williams, Joseph J; Rafferty, Anna N; Gopnik, Alison

    2017-01-01

    Three experiments investigate how self-generated explanation influences children's causal learning. Five-year-olds (N = 114) observed data consistent with two hypotheses and were prompted to explain or to report each observation. In Study 1, when making novel generalizations, explainers were more likely to favor the hypothesis that accounted for more observations. In Study 2, explainers favored a hypothesis that was consistent with prior knowledge. Study 3 pitted a hypothesis that accounted for more observations against a hypothesis consistent with prior knowledge. Explainers were more likely to base generalizations on prior knowledge. Findings suggest that attempts to explain drive children to evaluate hypotheses using features of "good" explanations, or those supporting generalizations with broad scope, as informed by children's prior knowledge and observations. © 2016 The Authors. Child Development © 2016 Society for Research in Child Development, Inc.

  10. Topology Explains Why Automobile Sunshades Fold Oddly

    ERIC Educational Resources Information Center

    Feist, Curtis; Naimi, Ramin

    2009-01-01

    Automobile sunshades always fold into an "odd" number of loops. The explanation why involves elementary topology (braid theory and linking number, both explained in detail here with definitions and examples), and an elementary fact from algebra about symmetric group.

  11. Topology Explains Why Automobile Sunshades Fold Oddly

    ERIC Educational Resources Information Center

    Feist, Curtis; Naimi, Ramin

    2009-01-01

    Automobile sunshades always fold into an "odd" number of loops. The explanation why involves elementary topology (braid theory and linking number, both explained in detail here with definitions and examples), and an elementary fact from algebra about symmetric group.

  12. Your Radiologist Explains Magnetic Resonance Angiography (MRA)

    MedlinePlus

    ... Sponsored by Image/Video Gallery Your Radiologist Explains Magnetic Resonance Angiography (MRA) Transcript Welcome to Radiology Info ... I’d like to talk with you about magnetic resonance angiography, or as it’s commonly known, MRA. ...

  13. Mining and Explaining Relationships in Wikipedia

    NASA Astrophysics Data System (ADS)

    Zhang, Xinpeng; Asano, Yasuhito; Yoshikawa, Masatoshi

    Mining and explaining relationships between concepts are challenging tasks in the field of knowledge search. We propose a new approach for the tasks using disjoint paths formed by links in Wikipedia. Disjoint paths are easy to understand and do not contain redundant information. To achieve this approach, we propose a naive method, as well as a generalized flow based method, and a technique for mining more disjoint paths using the generalized flow based method. We also apply the approach to classification of relationships. Our experiments reveal that the generalized flow based method can mine many disjoint paths important for understanding a relationship, and the classification is effective for explaining relationships.

  14. Explaining Autism: Its Discursive and Neuroanatomical Characteristics.

    ERIC Educational Resources Information Center

    Oller, John W., Jr.; Rascon, Dana

    This paper reviews the existing empirical research on autism in the context of the semiotic theories of Charles S. Peirce. His ideas of the generalized logic of relations are seen as explaining the unusual associations (or lack thereof) in autism. Concepts of "indices" or signs singling out distinct objects, and "adinity" or…

  15. How Employees Remain Happy: Explaining a Paradox

    ERIC Educational Resources Information Center

    Hutton, Dorothy M.; Atkinson, Barbara; Judd, Priya; Darling, Julie; Tran, Linh; Cummins, Robert A.

    2004-01-01

    This paper draws on subjective quality of life theory to explain findings from three studies of quality of work life. The studies were conducted with 346 regional process workers, metropolitan employment officers and nurses. The results support the adoption of the theory of homeostasis as an explanation for findings on subjective wellbeing at work…

  16. Differentiated Success: Combining Theories to Explain Learning

    ERIC Educational Resources Information Center

    Jorgensen, Robyn; Larkin, Kevin

    2015-01-01

    This paper explores the value of different paradigms to explain dispositions towards mathematics among primary school students from different social backgrounds. As part of a larger project designed to elicit students' thinking and attitudes towards mathematics, we seek to develop an explanatory model for the socially-differentiated outcomes in…

  17. 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…

  18. How Employees Remain Happy: Explaining a Paradox

    ERIC Educational Resources Information Center

    Hutton, Dorothy M.; Atkinson, Barbara; Judd, Priya; Darling, Julie; Tran, Linh; Cummins, Robert A.

    2004-01-01

    This paper draws on subjective quality of life theory to explain findings from three studies of quality of work life. The studies were conducted with 346 regional process workers, metropolitan employment officers and nurses. The results support the adoption of the theory of homeostasis as an explanation for findings on subjective wellbeing at work…

  19. NEW APPROACHES: The twins paradox explained

    NASA Astrophysics Data System (ADS)

    Linton, J. O.

    1997-09-01

    The well-known paradox of the space-travelling twins is easily stated, but it is not at all easy to explain, especially to a perspicacious audience. This essay attempts to set out an explanation (largely inspired by Paul Davies' book About Time [1]) which should be within the grasp of an intelligent sixth-former.

  20. Explaining the Sex Difference in Dyslexia

    ERIC Educational Resources Information Center

    Arnett, Anne B.; Pennington, Bruce F.; Peterson, Robin L.; Willcutt, Erik G.; DeFries, John C.; Olson, Richard K.

    2017-01-01

    Background: Males are diagnosed with dyslexia more frequently than females, even in epidemiological samples. This may be explained by greater variance in males' reading performance. Methods: We expand on previous research by rigorously testing the variance difference theory, and testing for mediation of the sex difference by cognitive correlates.…

  1. Explaining Pregnancy Loss: Parents' and Physicians' Attributions.

    ERIC Educational Resources Information Center

    Dunn, Dana S.; And Others

    1991-01-01

    Asked 138 females and 56 of their male partners to explain why they believed their spontaneous abortion, fetal or neonatal death, or ectopic pregnancy occurred. Explanations for loss included blaming mother, physical problems with mother or fetus, fate, or no explanation. Physicians' explanations related to gestational age of fetus, although…

  2. Explaining the Intergenerational Transmission of Divorce.

    ERIC Educational Resources Information Center

    Amato, Paul R.

    1996-01-01

    Uses national longitudinal data to explain the intergenerational transmission of divorce. Findings suggest that parental divorce elevates the risk of offspring divorce by increasing the likelihood that offspring exhibit behaviors that interfere with the maintenance of mutually rewarding intimate relationships. Offers four hypotheses for future…

  3. Do changes in connectivity explain desertification?

    USDA-ARS?s Scientific Manuscript database

    Desertification, broad-scale land degradation in drylands, is a major environmental hazard facing inhabitants of the world’s deserts as well as an important component of global change. There is no unifying framework that simply and effectively explains different forms of desertification. Here we arg...

  4. 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…

  5. Factors Explaining Faculty Technology Use and Productivity

    ERIC Educational Resources Information Center

    Xu, Yonghong; Meyer, Katrina A.

    2007-01-01

    This study examines factors related to technology use in teaching by university faculty. An EFA analysis of multiple questions of technology use in the classroom found two factors: one loaded with Web use and the second with email use. Therefore, three research questions were asked: What factors explain faculty use of the Web or email? Are these…

  6. Designing Agents to Support Learning by Explaining

    ERIC Educational Resources Information Center

    Holmes, Jeffrey

    2007-01-01

    Although prior research has shown that generating explanations encourages students to learn new content with deeper understanding and to monitor their own comprehension more effectively, helping students learn how to explain properly remains a significant challenge. This study investigated the use of software agents as learning partners in an…

  7. Explaining Pregnancy Loss: Parents' and Physicians' Attributions.

    ERIC Educational Resources Information Center

    Dunn, Dana S.; And Others

    1991-01-01

    Asked 138 females and 56 of their male partners to explain why they believed their spontaneous abortion, fetal or neonatal death, or ectopic pregnancy occurred. Explanations for loss included blaming mother, physical problems with mother or fetus, fate, or no explanation. Physicians' explanations related to gestational age of fetus, although…

  8. Heavy fermion behavior explained by bosons

    NASA Technical Reports Server (NTRS)

    Kallio, A.; Poykko, S.; Apaja, V.

    1995-01-01

    Conventional heavy fermion (HF) theories require existence of massive fermions. We show that heavy fermion phenomena can also be simply explained by existence of bosons with moderate mass but temperature dependent concentration below the formation temperature T(sub B), which in turn is close to room temperature. The bosons B(++) are proposed to be in chemical equilibrium with a system of holes h(+): B(++) = h(+) + h(+). This equilibrium is governed by a boson breaking function f(T), which determines the decreasing boson density and the increasing fermion density with increasing temperature. Since HF-compounds are hybridized from minimum two elements, we assume in addition existence of another fermion component h(sub s)(+) with temperature independent density. This spectator component is thought to be the main agent in binding the bosons in analogy with electronic or muonic molecules. Using a linear boson breaking function we can explain temperature dependence of the giant linear specific heat coefficient gamma(T) coming essentially from bosons. The maxima in resistivity, Hall coefficient, and susceptibility are explained by boson localization effects due to the Wigner crystallization. The antiferromagnetic transitions in turn are explained by similar localization of the pairing fermion system when their density n(sub h)(T(sub FL)) becomes lower than n(sub WC), the critical density of Wigner crystallization. The model applies irrespective whether a compound is superconducting or not. The same model explains the occurrence of low temperature antiferromagnetism also in high-T(sub c) superconductors. The double transition in UPt3 is proposed to be due to the transition of the pairing fermion liquid from spin polarized to unpolarized state.

  9. Children's Theories and the Drive to Explain

    NASA Astrophysics Data System (ADS)

    Schwitzgebel, Eric

    Debate has been growing in developmental psychology over how much the cognitive development of children is like theory change in science. Useful debate on this topic requires a clear understanding of what it would be for a child to have a theory. I argue that existing accounts of theories within philosophy of science and developmental psychology either are less precise than is ideal for the task or cannot capture everyday theorizing of the sort that children, if they theorize, must do. I then propose an account of theories that ties theories and explanation very closely together, treating theories primarily as products of a drive to explain. I clarify some of the positions people have taken regarding the theory theory of development, and I conclude by proposing that psychologists interested in the ''theory theory'' look for patterns of affect and arousal in development that would accompany the existence of a drive to explain.

  10. Explaining Underrepresentation: A Theory of Precluded Interest

    PubMed Central

    Plaut, Victoria C.

    2010-01-01

    What processes best explain women’s underrepresentation in science, math, and engineering fields in the U.S.? Do they also explain men’s underrepresentation in the humanities? Two survey studies across two U.S. West Coast universities (N = 62; N = 614) addressed these questions in the context of two fields: one male-dominated (computer science) and the other female-dominated (English). Among a set of social predictors—including perceived similarity to the people in the field, social identity threats, and expectations of success—the best mediator of women’s lower interest in computer science and men’s lower interest in English was perceived similarity. Thus, changing students’ social perceptions of how they relate to those in the field may help to diversify academic fields. PMID:20930923

  11. Explaining Underrepresentation: A Theory of Precluded Interest.

    PubMed

    Cheryan, Sapna; Plaut, Victoria C

    2010-10-01

    What processes best explain women's underrepresentation in science, math, and engineering fields in the U.S.? Do they also explain men's underrepresentation in the humanities? Two survey studies across two U.S. West Coast universities (N = 62; N = 614) addressed these questions in the context of two fields: one male-dominated (computer science) and the other female-dominated (English). Among a set of social predictors-including perceived similarity to the people in the field, social identity threats, and expectations of success-the best mediator of women's lower interest in computer science and men's lower interest in English was perceived similarity. Thus, changing students' social perceptions of how they relate to those in the field may help to diversify academic fields.

  12. Fletcher Explains Methods to Repair Skylab I

    NASA Technical Reports Server (NTRS)

    1973-01-01

    On May 23, 1973, Dr. James Fletcher Administrator for NASA, appeared before the United States Senate Committee on Aeronautical and Space Sciences. Dr. Fletcher explained to the committee what methods would be attempted to repair the damaged Skylab I. He stated that if the planned repairs were successful, that it would be possible to accomplish most of the activities scheduled for the two subsequent Skylab missions, each lasting 56 days.

  13. Explaining seeing? Disentangling qualia from perceptual organization.

    PubMed

    Ibáñez, Agustin; Bekinschtein, Tristan

    2010-09-01

    Abstract Visual perception and integration seem to play an essential role in our conscious phenomenology. Relatively local neural processing of reentrant nature may explain several visual integration processes (feature binding or figure-ground segregation, object recognition, inference, competition), even without attention or cognitive control. Based on the above statements, should the neural signatures of visual integration (via reentrant process) be non-reportable phenomenological qualia? We argue that qualia are not required to understand this perceptual organization.

  14. Norman Thagard Explains the Microgravity Vestibular Investigation

    NASA Technical Reports Server (NTRS)

    1992-01-01

    In this video, astronaut Norman Thagard explains how he and his fellow STS-42 crew mates interacted with the rotator chair for the Microgravity Vestibular Investigations (MVI) onboard the International Microgravity Laboratory in July 1992. In the MVI, researchers from Canada, the United States, and other countries examined the effects of orbital flight on the human orientation system to obtain a better understanding of the mechanisms of adaptation to orbit.

  15. Deglaciation explains bat extinction in the Caribbean.

    PubMed

    Dávalos, Liliana M; Russell, Amy L

    2012-12-01

    Ecological factors such as changing climate on land and interspecific competition have been debated as possible causes of postglacial Caribbean extinction. These hypotheses, however, have not been tested against a null model of climate-driven postglacial area loss. Here, we use a new Quaternary mammal database and deep-sea bathymetry to estimate species-area relationships (SARs) at present and during the Last Glacial Maximum (LGM) for bats of the Caribbean, and to model species loss as a function of area loss from rising sea level. Island area was a significant predictor of species richness in the Bahamas, Greater Antilles, and Lesser Antilles at all time periods, except for the Lesser Antilles during the LGM. Parameters of LGM and current SARs were similar in the Bahamas and Greater Antilles, but not the Lesser Antilles, which had fewer estimated species during the LGM than expected given their size. Estimated postglacial species losses in the Bahamas and Greater Antilles were largely explained by inferred area loss from rising sea level in the Holocene. However, there were more species in the Bahamas at present, and fewer species in the smaller Greater Antilles, than expected given island size and the end-Pleistocene/early Holocene SARs. Poor fossil sampling and ecological factors may explain these departures from the null. Our analyses illustrate the importance of changes in area in explaining patterns of species richness through time and emphasize the role of the SAR as a null hypothesis in explorations of the impact of novel ecological interactions on extinction.

  16. Deglaciation explains bat extinction in the Caribbean

    PubMed Central

    Dávalos, Liliana M; Russell, Amy L

    2012-01-01

    Ecological factors such as changing climate on land and interspecific competition have been debated as possible causes of postglacial Caribbean extinction. These hypotheses, however, have not been tested against a null model of climate-driven postglacial area loss. Here, we use a new Quaternary mammal database and deep-sea bathymetry to estimate species–area relationships (SARs) at present and during the Last Glacial Maximum (LGM) for bats of the Caribbean, and to model species loss as a function of area loss from rising sea level. Island area was a significant predictor of species richness in the Bahamas, Greater Antilles, and Lesser Antilles at all time periods, except for the Lesser Antilles during the LGM. Parameters of LGM and current SARs were similar in the Bahamas and Greater Antilles, but not the Lesser Antilles, which had fewer estimated species during the LGM than expected given their size. Estimated postglacial species losses in the Bahamas and Greater Antilles were largely explained by inferred area loss from rising sea level in the Holocene. However, there were more species in the Bahamas at present, and fewer species in the smaller Greater Antilles, than expected given island size and the end-Pleistocene/early Holocene SARs. Poor fossil sampling and ecological factors may explain these departures from the null. Our analyses illustrate the importance of changes in area in explaining patterns of species richness through time and emphasize the role of the SAR as a null hypothesis in explorations of the impact of novel ecological interactions on extinction. PMID:23301171

  17. Dissipative dark matter explains rotation curves

    NASA Astrophysics Data System (ADS)

    Foot, R.

    2015-06-01

    Dissipative dark matter, where dark matter particles interact with a massless (or very light) boson, is studied. Such dark matter can arise in simple hidden sector gauge models, including those featuring an unbroken U (1 )' gauge symmetry, leading to a dark photon. Previous work has shown that such models can not only explain the large scale structure and cosmic microwave background, but potentially also dark matter phenomena on small scales, such as the inferred cored structure of dark matter halos. In this picture, dark matter halos of disk galaxies not only cool via dissipative interactions but are also heated via ordinary supernovae (facilitated by an assumed photon-dark photon kinetic mixing interaction). This interaction between the dark matter halo and ordinary baryons, a very special feature of these types of models, plays a critical role in governing the physical properties of the dark matter halo. Here, we further study the implications of this type of dissipative dark matter for disk galaxies. Building on earlier work, we develop a simple formalism which aims to describe the effects of dissipative dark matter in a fairly model independent way. This formalism is then applied to generic disk galaxies. We also consider specific examples, including NGC 1560 and a sample of dwarf galaxies from the LITTLE THINGS survey. We find that dissipative dark matter, as developed here, does a fairly good job accounting for the rotation curves of the galaxies considered. Not only does dissipative dark matter explain the linear rise of the rotational velocity of dwarf galaxies at small radii, but it can also explain the observed wiggles in rotation curves which are known to be correlated with corresponding features in the disk gas distribution.

  18. Weaker dental enamel explains dental decay.

    PubMed

    Vieira, Alexandre R; Gibson, Carolyn W; Deeley, Kathleen; Xue, Hui; Li, Yong

    2015-01-01

    Dental caries continues to be the most prevalent bacteria-mediated non-contagious disease of humankind. Dental professionals assert the disease can be explained by poor oral hygiene and a diet rich in sugars but this does not account for caries free individuals exposed to the same risk factors. In order to test the hypothesis that amount of amelogenin during enamel development can influence caries susceptibility, we generated multiple strains of mice with varying levels of available amelogenin during dental development. Mechanical tests showed that dental enamel developed with less amelogenin is "weaker" while the dental enamel of animals over-expressing amelogenin appears to be more resistant to acid dissolution.

  19. Colour-coded waste disposal explained.

    PubMed

    Turner, Nigel

    2007-08-01

    The long-awaited guidance document from the Department of Health is colourful in more ways then one. Health Technical Memorandum (HTM) 07-01: Safe Management of Healthcare Waste was published in December 2006 and replaced the old "purple book" (The Safe Management of Clinical Waste). Was it a sign of things to come that the old guidance had a purple cover, a colour which is now used to indicate cytotoxic and cytostatic wastes? Catalyst Waste Solutions' managing director Nigel Turner explains the new legislation.

  20. Life-Saving Space Technology Explained

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Dr. Harry Whelan, a pediatric Neurologist at the Medical Hospital of Wisconsin in Milwaukee and professor of Neurology at the Medical College of Wisconsin, explains the operation of light-emitting diodes (LEDs) developed for use in space plant growth experiments and now adapted for use in photodynamic therapy, a technique in which light from the LEDs activates light-sensitive, tumor-treating drugs. The technique has been used in at least two surgeries on brain tumors. The LED project was one of several NASA exhibits at AirVenture 2000 sponsored by the Experimental Aircraft Association in Oshkosh, WI.

  1. Does information theory explain biological evolution?

    NASA Astrophysics Data System (ADS)

    Battail, G.

    1997-11-01

    It is suggested that Dawkins' model of evolution needs error-correction coding in the genome replication process. Nested coding is moreover assumed. Consequences of these hypotheses are drawn using fundamental results of information theory. Genome replication is dealt with independently of phenotype encoding, which pertains to semantics. The proposed hypotheses enable explaining facts of genetics and evolution, including the existence of redundant DNA (the introns), the observed correlation between the rate of mutations on the one hand, the genome length and the redundancy rate on the other hand, the discreteness of species and the trend of eukaryotes evolution towards complexity.

  2. Life-Saving Space Technology Explained

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Dr. Harry Whelan, a pediatric Neurologist at the Medical Hospital of Wisconsin in Milwaukee and professor of Neurology at the Medical College of Wisconsin, explains the operation of light-emitting diodes (LEDs) developed for use in space plant growth experiments and now adapted for use in photodynamic therapy, a technique in which light from the LEDs activates light-sensitive, tumor-treating drugs. The technique has been used in at least two surgeries on brain tumors. The LED project was one of several NASA exhibits at AirVenture 2000 sponsored by the Experimental Aircraft Association in Oshkosh, WI.

  3. Chromosome congression explained by nanoscale electrostatics.

    PubMed

    Gagliardi, L John; Shain, Daniel H

    2014-02-24

    Nanoscale electrostatic microtubule disassembly forces between positively charged molecules in kinetochores and negative charges on plus ends of microtubules have been implicated in poleward chromosome motions and may also contribute to antipoleward chromosome movements. We propose that chromosome congression can be understood in terms of antipoleward nanoscale electrostatic microtubule assembly forces between negatively charged microtubule plus ends and like-charged chromosome arms, acting in conjunction with poleward microtubule disassembly forces. Several other aspects of post-attachment prometaphase chromosome motions, as well as metaphase oscillations, are consistently explained within this framework.

  4. Developmental systems theory: what does it explain, and how does it explain it?

    PubMed

    Griffiths, Paul E; Tabery, James

    2013-01-01

    We examine developmental systems theory (DST) with two questions in mind: What does DST explain? How does DST explain it? To answer these questions, we start by reviewing major contributions to the origins of DST: the introduction of the idea of a "developmental system", the idea of probabilistic epigenesis, the attention to the role of information in the developmental system, and finally the explicit identification of a DST. We then consider what DST is not, contrasting it with two approaches that have been foils for DST: behavioral genetics and nativist cognitive psychology. Third, we distill out two core concepts that have defined DSTthroughout its history: epigenesis and developmental dynamics. Finally, we turn to how DST explains, arguing that it explains by elucidating mechanisms.

  5. Boosted Regression Tree Models to Explain Watershed ...

    EPA Pesticide Factsheets

    Boosted regression tree (BRT) models were developed to quantify the nonlinear relationships between landscape variables and nutrient concentrations in a mesoscale mixed land cover watershed during base-flow conditions. Factors that affect instream biological components, based on the Index of Biotic Integrity (IBI), were also analyzed. Seasonal BRT models at two spatial scales (watershed and riparian buffered area [RBA]) for nitrite-nitrate (NO2-NO3), total Kjeldahl nitrogen, and total phosphorus (TP) and annual models for the IBI score were developed. Two primary factors — location within the watershed (i.e., geographic position, stream order, and distance to a downstream confluence) and percentage of urban land cover (both scales) — emerged as important predictor variables. Latitude and longitude interacted with other factors to explain the variability in summer NO2-NO3 concentrations and IBI scores. BRT results also suggested that location might be associated with indicators of sources (e.g., land cover), runoff potential (e.g., soil and topographic factors), and processes not easily represented by spatial data indicators. Runoff indicators (e.g., Hydrological Soil Group D and Topographic Wetness Indices) explained a substantial portion of the variability in nutrient concentrations as did point sources for TP in the summer months. The results from our BRT approach can help prioritize areas for nutrient management in mixed-use and heavily impacted watershed

  6. Mach bands explained by response normalization

    PubMed Central

    Kingdom, Frederick A. A.

    2014-01-01

    Mach bands are the illusory dark and bright bars seen at the foot and knee of a luminance trapezoid. First demonstrated by Ernst Mach in the latter part of the 19th century, Mach bands are a test bed not only for models of brightness illusions but of spatial vision in general. Up until 50 years ago the dominant explanation of Mach Bands was that they were caused by lateral inhibition among retinal neurons. More recently, the dominant idea has been that Mach bands are a consequence of a visual process that generates a sparse, binary description of the image in terms of “edges” and “bars”. Another recent explanation is that Mach bands result from learned expectations about the pattern of light typically found on sharply curved surfaces. In keeping with recent multi-scale filtering accounts of brightness illusions as well as current physiology, I show however that Mach bands are most simply explained by response normalization, whereby the gains of early visual channels are adjusted on a local basis to make their responses more equal. I show that a simple one-dimensional model of response normalization explains the range of conditions under which Mach bands occur, and as importantly, the conditions under which they do not occur. PMID:25408643

  7. EXPLAINING THE ASSOCIATION BETWEEN INCARCERATION AND DIVORCE*

    PubMed Central

    Siennick, Sonja E.; Stewart, Eric A.; Staff, Jeremy

    2014-01-01

    Recent studies have suggested that incarceration dramatically increases the odds of divorce, but we know little about the mechanisms that explain the association. This study uses prospective longitudinal data from a subset of married young adults in the National Longitudinal Study of Adolescent Health (N = 1,919) to examine whether incarceration is associated with divorce indirectly via low marital love, economic strain, relationship violence, and extramarital sex. The findings confirmed that incarcerations occurring during, but not before, a marriage were associated with an increased hazard of divorce. Incarcerations occurring during marriage also were associated with less marital love, more relationship violence, more economic strain, and greater odds of extramarital sex. Above-average levels of economic strain were visible among respondents observed preincarceration, but only respondents observed postincarceration showed less marital love, more relationship violence, and higher odds of extramarital sex than did respondents who were not incarcerated during marriage. These relationship problems explained approximately 40 percent of the association between incarceration and marital dissolution. These findings are consistent with theoretical predictions that a spouse’s incarceration alters the rewards and costs of the marriage and the relative attractiveness of alternative partners. PMID:25598544

  8. How to explain Si isotopes of chert?

    NASA Astrophysics Data System (ADS)

    Liu, Y.

    2016-12-01

    The variations of d30Si values in diagenetic chert and chert- associated BIFs over time can be used to reconstruct the environmental conditions of the early Earth, and become a hot topic in the Si isotope society. However, there are several different views of explaining the variation of d30Si values over time. Moreover, there are disputes in explaining the distribution of Si isotope in several main reservoirs in surface systems. Those disagreements are caused by lacking key Si isotope fractionation factors associated with the formation processes of chert and its altered products. There are many unexplained observations about Si isotope distributions in Earth's surface systems (Opfergelt and Delmelle, 2012). For example, the deduced Si isotope equilibrium fractionation factors by Rayleigh model at ambient temperature between clay and the solution D30Siclay-solution = -1.5 ‰ and -2.05 ‰ (Hughes et al., 2013) obviously disagree with common sense, which dictates that stiffer chemical bonds will enrich heavier isotopes, i.e., the precipitated minerals will preferentially incorporate heavy isotopes relative to aqueous H4SiO4 due to their shorter Si-O bonds. Another similar case is the fractionation between quartz and solution. Most field observations suggested that solution will be enriched with heavier Si isotope compared to quartz, conflicting to the fact that quartz is the one with much shorter Si-O bonds than aqueous H4SiO4 (ca. 1.610Å vs. 1.639Å). Here we provide equilibrium and kinetic Si isotope fractionation factors associated with the formation of amorphous quartz and other secondary minerals in polymerization, co-precipitation and adsorption processes. The adsorption processes of silica gel to Fe-hydroxides have been carefully examined. The Si isotope fractionations due to the formation of mono-dentate to quadru-dentate adsorbed Fe-Si complexes have been calculated. These data can explain well the experimental observations (e.g., Zheng et al., 2016) and

  9. Age and disability: explaining the wage differential.

    PubMed

    Gannon, Brenda; Munley, Margaret

    2009-07-01

    This paper estimates the level of explained and unexplained factors that contribute to the wage gap between workers with and without disabilities, providing benchmark estimates for Ireland. It separates out the confounding impact of productivity differences between disabled and non-disabled, by comparing wage differentials across three groups, disabled with limitations, disabled without limitations and non-disabled. Furthermore, data are analysed for the years 1995-2001 and two sub-samples pre and post 1998 allow us to decompose wage differentials before and after the Employment Equality Act 1998. Results are comparable to those of the UK and the unexplained component (upper bound of discrimination) is lower once we control for productivity differences. The lower bound level depends on the contribution of unobserved effects and the validity of the selection component in the decomposition model.

  10. What optimization principle explains the zebrafish vasculature?

    NASA Astrophysics Data System (ADS)

    Chang, Shyr-Shea; Baek, Kyung In; Hsiai, Tzung; Roper, Marcus

    2016-11-01

    Many multicellular organisms depend on biological transport networks; from the veins of leaves to the animal circulatory system, to redistribute nutrients internally. Since natural selection rewards efficiency, those networks are thought to minimize the cost of maintaining the flow inside. But optimizing these costs creates tradeoffs with other functions, e.g. mixing or uniform distribution of nutrients. We develop an extended Lagrange multiplier approach that allows the optimization of general network functionals. We also follow the real zebrafish vasculature and blood flows during organism development. Taken together, our work shows that the challenge of uniform oxygen perfusion, and not transport efficiency, explain zebrafish vascular organization. Ruth L. Kirschstein National Research Service Award (T32-GM008185).

  11. Explaining the gender difference in nightmare frequency.

    PubMed

    Schredl, Michael

    2014-01-01

    A recent meta-analysis showed a robust gender difference in nightmare frequency of medium effect size in adolescents and young adults: Women tend to report nightmares more frequently than men. The present study, carried out in an unselected student sample, indicates that 2 factors mediate the gender difference in nightmare frequency: neuroticism and overall dream recall frequency. The effect of neuroticism on the gender difference and the finding that the gender difference in nightmare frequency emerges at an age of about 10 years suggest that gender-specific socialization processes may play an important role in explaining the gender differences in nightmare frequency in adolescents and young to middle-aged adults. This idea is supported by the previous finding that nightmare frequency is related to sex role orientation. However, longitudinal studies are necessary to validate these hypotheses.

  12. Mating ecology explains patterns of genome elimination

    PubMed Central

    Gardner, Andy; Ross, Laura

    2014-01-01

    Genome elimination – whereby an individual discards chromosomes inherited from one parent, and transmits only those inherited from the other parent – is found across thousands of animal species. It is more common in association with inbreeding, under male heterogamety, in males, and in the form of paternal genome elimination. However, the reasons for this broad pattern remain unclear. We develop a mathematical model to determine how degree of inbreeding, sex determination, genomic location, pattern of gene expression and parental origin of the eliminated genome interact to determine the fate of genome-elimination alleles. We find that: inbreeding promotes paternal genome elimination in the heterogametic sex; this may incur population extinction under female heterogamety, owing to eradication of males; and extinction is averted under male heterogamety, owing to countervailing sex-ratio selection. Thus, we explain the observed pattern of genome elimination. Our results highlight the interaction between mating system, sex-ratio selection and intragenomic conflict. PMID:25328085

  13. Explaining Today's Physics Through History and Biography

    NASA Astrophysics Data System (ADS)

    Lindley, David

    2014-03-01

    Quantum computers, string theory, holographic universes - to the general audience, today's physics can be as mystifying as it is fascinating. But modern ideas evolved from an earlier phase of physics - Newtonian mechanics, simple cause and effect - that is in principle easier for the non-expert to grasp. I have found that writing about physics from a historical and biographical perspective is an effective way to convey modern thinking by explaining where it comes from - it is a way of carrying the reader from concepts that make intuitive sense to ideas that seem, on first encounter, utterly bizarre. Smuggling explanations into stories satisfies the reader's desire for narrative - bearing in mind that narrative can include the evolution of ideas as well as tales about intriguing and original people.

  14. Macromolecular crowding explains overflow metabolism in cells

    PubMed Central

    Vazquez, Alexei; Oltvai, Zoltán N.

    2016-01-01

    Overflow metabolism is a metabolic phenotype of cells characterized by mixed oxidative phosphorylation (OxPhos) and fermentative glycolysis in the presence of oxygen. Recently, it was proposed that a combination of a protein allocation constraint and a higher proteome fraction cost of energy generation by OxPhos relative to fermentation form the basis of overflow metabolism in the bacterium, Escherichia coli. However, we argue that the existence of a maximum or optimal macromolecular density is another essential requirement. Here we re-evaluate our previous theory of overflow metabolism based on molecular crowding following the proteomic fractions formulation. We show that molecular crowding is a key factor in explaining the switch from OxPhos to overflow metabolism. PMID:27484619

  15. Weaker Dental Enamel Explains Dental Decay

    PubMed Central

    Vieira, Alexandre R.; Gibson, Carolyn W.; Deeley, Kathleen; Xue, Hui; Li, Yong

    2015-01-01

    Dental caries continues to be the most prevalent bacteria-mediated non-contagious disease of humankind. Dental professionals assert the disease can be explained by poor oral hygiene and a diet rich in sugars but this does not account for caries free individuals exposed to the same risk factors. In order to test the hypothesis that amount of amelogenin during enamel development can influence caries susceptibility, we generated multiple strains of mice with varying levels of available amelogenin during dental development. Mechanical tests showed that dental enamel developed with less amelogenin is “weaker” while the dental enamel of animals over-expressing amelogenin appears to be more resistant to acid dissolution. PMID:25885796

  16. Explaining mutualism variation: a new evolutionary paradox?

    PubMed

    Heath, Katy D; Stinchcombe, John R

    2014-02-01

    The paradox of mutualism is typically framed as the persistence of interspecific cooperation, despite the potential advantages of cheating. Thus, mutualism research has tended to focus on stabilizing mechanisms that prevent the invasion of low-quality partners. These mechanisms alone cannot explain the persistence of variation for partner quality observed in nature, leaving a large gap in our understanding of how mutualisms evolve. Studying partner quality variation is necessary for applying genetically explicit models to predict evolution in natural populations, a necessary step for understanding the origins of mutualisms as well as their ongoing dynamics. An evolutionary genetic approach, which is focused on naturally occurring mutualist variation, can potentially synthesize the currently disconnected fields of mutualism evolution and coevolutionary genetics. We outline explanations for the maintenance of genetic variation for mutualism and suggest approaches necessary to address them.

  17. Mating ecology explains patterns of genome elimination.

    PubMed

    Gardner, Andy; Ross, Laura

    2014-12-01

    Genome elimination - whereby an individual discards chromosomes inherited from one parent, and transmits only those inherited from the other parent - is found across thousands of animal species. It is more common in association with inbreeding, under male heterogamety, in males, and in the form of paternal genome elimination. However, the reasons for this broad pattern remain unclear. We develop a mathematical model to determine how degree of inbreeding, sex determination, genomic location, pattern of gene expression and parental origin of the eliminated genome interact to determine the fate of genome-elimination alleles. We find that: inbreeding promotes paternal genome elimination in the heterogametic sex; this may incur population extinction under female heterogamety, owing to eradication of males; and extinction is averted under male heterogamety, owing to countervailing sex-ratio selection. Thus, we explain the observed pattern of genome elimination. Our results highlight the interaction between mating system, sex-ratio selection and intragenomic conflict.

  18. Bell Test experiments explained without entanglement

    NASA Astrophysics Data System (ADS)

    Boyd, Jeffrey

    2011-04-01

    by Jeffrey H. Boyd. Jeffreyhboyd@gmail.com. John Bell proposed a test of what was called "local realism." However that is a different view of reality than we hold. Bell incorrectly assumed the validity of wave particle dualism. According to our model waves are independent of particles; wave interference precedes the emission of a particle. This results in two conclusions. First the proposed inequalities that apply to "local realism" in Bell's theorem do not apply to this model. The alleged mathematics of "local realism" is therefore wrong. Second, we can explain the Bell Test experimental results (such as the experiments done at Innsbruck) without any need for entanglement, non-locality, or particle superposition.

  19. Explaining evolution via constrained persistent perfect phylogeny.

    PubMed

    Bonizzoni, Paola; Carrieri, Anna Paola; Della Vedova, Gianluca; Trucco, Gabriella

    2014-01-01

    The perfect phylogeny is an often used model in phylogenetics since it provides an efficient basic procedure for representing the evolution of genomic binary characters in several frameworks, such as for example in haplotype inference. The model, which is conceptually the simplest, is based on the infinite sites assumption, that is no character can mutate more than once in the whole tree. A main open problem regarding the model is finding generalizations that retain the computational tractability of the original model but are more flexible in modeling biological data when the infinite site assumption is violated because of e.g. back mutations. A special case of back mutations that has been considered in the study of the evolution of protein domains (where a domain is acquired and then lost) is persistency, that is the fact that a character is allowed to return back to the ancestral state. In this model characters can be gained and lost at most once. In this paper we consider the computational problem of explaining binary data by the Persistent Perfect Phylogeny model (referred as PPP) and for this purpose we investigate the problem of reconstructing an evolution where some constraints are imposed on the paths of the tree. We define a natural generalization of the PPP problem obtained by requiring that for some pairs (character, species), neither the species nor any of its ancestors can have the character. In other words, some characters cannot be persistent for some species. This new problem is called Constrained PPP (CPPP). Based on a graph formulation of the CPPP problem, we are able to provide a polynomial time solution for the CPPP problem for matrices whose conflict graph has no edges. Using this result, we develop a parameterized algorithm for solving the CPPP problem where the parameter is the number of characters. A preliminary experimental analysis shows that the constrained persistent perfect phylogeny model allows to explain efficiently data that do not

  20. Explaining Polarization Reversals in STEREO Wave Data

    NASA Technical Reports Server (NTRS)

    Breneman, A.; Cattell, C.; Wygant, J.; Kersten, K.; Wilson, L, B., III; Dai, L.; Colpitts, C.; Kellogg, P. J.; Goetz, K.; Paradise, A.

    2012-01-01

    Recently Breneman et al. reported observations of large amplitude lightning and transmitter whistler mode waves from two STEREO passes through the inner radiation belt (L<2). Hodograms of the electric field in the plane transverse to the magnetic field showed that the transmitter waves underwent periodic polarization reversals. Specifically, their polarization would cycle through a pattern of right-hand to linear to left-hand polarization at a rate of roughly 200 Hz. The lightning whistlers were observed to be left-hand polarized at frequencies greater than the lower hybrid frequency and less than the transmitter frequency (21.4 kHz) and right-hand polarized otherwise. Only righthand polarized waves in the inner radiation belt should exist in the frequency range of the whistler mode and these reversals were not explained in the previous paper. We show, with a combination of observations and simulated wave superposition, that these polarization reversals are due to the beating of an incident electromagnetic whistler mode wave at 21.4 kHz and linearly polarized, symmetric lower hybrid sidebands Doppler-shifted from the incident wave by +/-200 Hz. The existence of the lower hybrid waves is consistent with the parametric decay mechanism of Lee and Kuo whereby an incident whistler mode wave decays into symmetric, short wavelength lower hybrid waves and a purely growing (zero-frequency) mode. Like the lower hybrid waves, the purely growing mode is Doppler-shifted by 200 Hz as observed on STEREO. This decay mechanism in the upper ionosphere has been previously reported at equatorial latitudes and is thought to have a direct connection with explosive spread F enhancements. As such it may represent another dissipation mechanism of VLF wave energy in the ionosphere and may help to explain a deficit of observed lightning and transmitter energy in the inner radiation belts as reported by Starks et al.

  1. HF-Explain: a natural language generation system for explaining a medical expert system.

    PubMed Central

    Lewin, H. C.

    1991-01-01

    Causal models have been used, with considerable success, to reason in the medical domain. While these systems typically have a robust reasoning mechanism and knowledge base about their specific area of expertise, their ability to satisfactorily explain their results in a meaningful, coherent and concise manner has been less impressive then their diagnostic capabilities. This paper describes a program, HF-Explain, that generates natural language explanations of one such system--the Heart Failure Program. HF-Explain, is loosely based on work done by McKeown in the Text system, using augmented transition networks (ATN) as a formalism to guide the explanation process. The result is a coherent, concise, accurate and rich explanation of Heart Failure Programs' diagnostic hypotheses. PMID:1807682

  2. Explaining evolution via constrained persistent perfect phylogeny

    PubMed Central

    2014-01-01

    Background The perfect phylogeny is an often used model in phylogenetics since it provides an efficient basic procedure for representing the evolution of genomic binary characters in several frameworks, such as for example in haplotype inference. The model, which is conceptually the simplest, is based on the infinite sites assumption, that is no character can mutate more than once in the whole tree. A main open problem regarding the model is finding generalizations that retain the computational tractability of the original model but are more flexible in modeling biological data when the infinite site assumption is violated because of e.g. back mutations. A special case of back mutations that has been considered in the study of the evolution of protein domains (where a domain is acquired and then lost) is persistency, that is the fact that a character is allowed to return back to the ancestral state. In this model characters can be gained and lost at most once. In this paper we consider the computational problem of explaining binary data by the Persistent Perfect Phylogeny model (referred as PPP) and for this purpose we investigate the problem of reconstructing an evolution where some constraints are imposed on the paths of the tree. Results We define a natural generalization of the PPP problem obtained by requiring that for some pairs (character, species), neither the species nor any of its ancestors can have the character. In other words, some characters cannot be persistent for some species. This new problem is called Constrained PPP (CPPP). Based on a graph formulation of the CPPP problem, we are able to provide a polynomial time solution for the CPPP problem for matrices whose conflict graph has no edges. Using this result, we develop a parameterized algorithm for solving the CPPP problem where the parameter is the number of characters. Conclusions A preliminary experimental analysis shows that the constrained persistent perfect phylogeny model allows to

  3. Ocean currents help explain population genetic structure

    PubMed Central

    White, Crow; Selkoe, Kimberly A.; Watson, James; Siegel, David A.; Zacherl, Danielle C.; Toonen, Robert J.

    2010-01-01

    Management and conservation can be greatly informed by considering explicitly how environmental factors influence population genetic structure. Using simulated larval dispersal estimates based on ocean current observations, we demonstrate how explicit consideration of frequency of exchange of larvae among sites via ocean advection can fundamentally change the interpretation of empirical population genetic structuring as compared with conventional spatial genetic analyses. Both frequency of larval exchange and empirical genetic difference were uncorrelated with Euclidean distance between sites. When transformed into relative oceanographic distances and integrated into a genetic isolation-by-distance framework, however, the frequency of larval exchange explained nearly 50 per cent of the variance in empirical genetic differences among sites over scales of tens of kilometres. Explanatory power was strongest when we considered effects of multiple generations of larval dispersal via intermediary locations on the long-term probability of exchange between sites. Our results uncover meaningful spatial patterning to population genetic structuring that corresponds with ocean circulation. This study advances our ability to interpret population structure from complex genetic data characteristic of high gene flow species, validates recent advances in oceanographic approaches for assessing larval dispersal and represents a novel approach to characterize population connectivity at small spatial scales germane to conservation and fisheries management. PMID:20133354

  4. Ocean currents help explain population genetic structure.

    PubMed

    White, Crow; Selkoe, Kimberly A; Watson, James; Siegel, David A; Zacherl, Danielle C; Toonen, Robert J

    2010-06-07

    Management and conservation can be greatly informed by considering explicitly how environmental factors influence population genetic structure. Using simulated larval dispersal estimates based on ocean current observations, we demonstrate how explicit consideration of frequency of exchange of larvae among sites via ocean advection can fundamentally change the interpretation of empirical population genetic structuring as compared with conventional spatial genetic analyses. Both frequency of larval exchange and empirical genetic difference were uncorrelated with Euclidean distance between sites. When transformed into relative oceanographic distances and integrated into a genetic isolation-by-distance framework, however, the frequency of larval exchange explained nearly 50 per cent of the variance in empirical genetic differences among sites over scales of tens of kilometres. Explanatory power was strongest when we considered effects of multiple generations of larval dispersal via intermediary locations on the long-term probability of exchange between sites. Our results uncover meaningful spatial patterning to population genetic structuring that corresponds with ocean circulation. This study advances our ability to interpret population structure from complex genetic data characteristic of high gene flow species, validates recent advances in oceanographic approaches for assessing larval dispersal and represents a novel approach to characterize population connectivity at small spatial scales germane to conservation and fisheries management.

  5. Proposed Pathophysiologic Framework to Explain Some ...

    EPA Pesticide Factsheets

    The paper proposes a pathophysiologic framework to explain the well-established epidemiological association between exposure to ambient air particle pollution and premature cardiovascular mortality, and offers insights into public health solutions that extend beyond regularory environmental protections to actions that can be taken by individuals, public health officials, healthcare professionals, city and regional planners, local and state governmental officials and all those who possess the capacity to improve cardiovascular health within the popula­tion.The foundation of the framework rests on the contribution of traditional cardiovascular risk factors acting alone and in concert with long-term exposures to air pollutants to create a conditional susceptibility for clinical vascular events, such as myocardial ischemia and infarction; stroke and lethal ventricular arrhythmias. The conceprual framework focuses on the fact that short-term exposures to ambient air particulate matter (PM) are associated with vascular thrombosis (acute coronary syndrome. stroke, deep venous thrombosis. and pulmonary embolism ) and electrical dysfunction (ventricular arrhythmia); and that individuals having prevalent heart disease are at greatest risk. Moreover, exposure is concomitant with changes in autonomic nervous system balance, systemic in­flammation, and prothrombotic/anti-thrombotic and profibrinolytic-antifibrinolytic balance.Thus, a comprehensive solution to the problem o

  6. Phenotypic variation explains food web structural patterns.

    PubMed

    Gibert, Jean P; DeLong, John P

    2017-10-02

    Food webs (i.e., networks of species and their feeding interactions) share multiple structural features across ecosystems. The factors explaining such similarities are still debated, and the role played by most organismal traits and their intraspecific variation is unknown. Here, we assess how variation in traits controlling predator-prey interactions (e.g., body size) affects food web structure. We show that larger phenotypic variation increases connectivity among predators and their prey as well as total food intake rate. For predators able to eat only a few species (i.e., specialists), low phenotypic variation maximizes intake rates, while the opposite is true for consumers with broader diets (i.e., generalists). We also show that variation sets predator trophic level by determining interaction strengths with prey at different trophic levels. Merging these results, we make two general predictions about the structure of food webs: (i) trophic level should increase with predator connectivity, and (ii) interaction strengths should decrease with prey trophic level. We confirm these predictions empirically using a global dataset of well-resolved food webs. Our results provide understanding of the processes structuring food webs that include functional traits and their naturally occurring variation. Published under the PNAS license.

  7. Can Thermal Nonequilibrium Explain Coronal Loops?

    NASA Technical Reports Server (NTRS)

    Klimchuk, James A.; Karpen, Judy T.; Antiochos, Spiro K.

    2010-01-01

    Any successful model of coronal loops must explain a number of observed properties. For warm (approx. 1 MK) loops, these include: 1. excess density, 2. flat temperature profile, 3. super-hydrostatic scale height, 4. unstructured intensity profile, and 5. 1000-5000 s lifetime. We examine whether thermal nonequilibrium can reproduce the observations by performing hydrodynamic simulations based on steady coronal heating that decreases exponentially with height. We consider both monolithic and multi-stranded loops. The simulations successfully reproduce certain aspects of the observations, including the excess density, but each of them fails in at least one critical way. -Xonolithic models have far too much intensity structure, while multi-strand models are either too structured or too long-lived. Storms of nanoflares remain the only viable explanation for warm loops that has been proposed so far. Our results appear to rule out the widespread existence of heating that is both highly concentrated low in the corona and steady or quasi-steady (slowly varying or impulsive with a rapid cadence). Active regions would have a very different appearance if the dominant heating mechanism had these properties. Thermal nonequilibrium may nonetheless play an important role in prominences and catastrophic cooling e(veen.gts..,coronal rain) that occupy a small fraction of the coronal volume. However, apparent inconsistencies between the models and observations of cooling events have yet to be understood.

  8. Explaining opinion polarisation with opinion copulas

    PubMed Central

    2017-01-01

    An empirically founded and widely established driving force in opinion dynamics is homophily i.e. the tendency of “birds of a feather” to “flock together”. The closer our opinions are the more likely it is that we will interact and converge. Models using these assumptions are called bounded confidence models (BCM) as they assume a tolerance threshold after which interaction is unlikely. They are known to produce one or more clusters, depending on the size of the bound, with more than one cluster being possible only in the deterministic case. Introducing noise, as is likely to happen in a stochastic world, causes BCM to produce consensus which leaves us with the open problem of explaining the emergence and sustainance of opinion clusters and polarisation. We investigate the role of heterogeneous priors in opinion formation, introduce the concept of opinion copulas, argue that it is well supported by findings in Social Psychology and use it to show that the stochastic BCM does indeed produce opinion clustering without the need for extra assumptions. PMID:28829802

  9. Explaining variance in black carbon's aging timescale

    NASA Astrophysics Data System (ADS)

    Fierce, L.; Riemer, N.; Bond, T. C.

    2015-03-01

    The size and composition of particles containing black carbon (BC) are modified soon after emission by condensation of semivolatile substances and coagulation with other particles, known collectively as "aging" processes. Although this change in particle properties is widely recognized, the timescale for transformation is not well constrained. In this work, we simulated aerosol aging with the particle-resolved model PartMC-MOSAIC (Particle Monte Carlo - Model for Simulating Aerosol Interactions and Chemistry) and extracted aging timescales based on changes in particle cloud condensation nuclei (CCN). We simulated nearly 300 scenarios and, through a regression analysis, identified the key parameters driving the value of the aging timescale. We show that BC's aging timescale spans from hours to weeks, depending on the local environmental conditions and the characteristics of the fresh BC-containing particles. Although the simulations presented in this study included many processes and particle interactions, we show that 80% of the variance in the aging timescale is explained by only a few key parameters. The condensation aging timescale decreased with the flux of condensing aerosol and was shortest for the largest fresh particles, while the coagulation aging timescale decreased with the total number concentration of large (D >100 nm), CCN-active particles and was shortest for the smallest fresh particles. Therefore, both condensation and coagulation play important roles in aging, and their relative impact depends on the particle size range.

  10. Explaining the Cambrian "Explosion" of Animals

    NASA Astrophysics Data System (ADS)

    Marshall, Charles R.

    2006-05-01

    The Cambrian "explosion" is a unique episode in Earth history, when essentially all the animal phyla first appear in the fossil record. A variety of environmental, developmental (genetic), and ecological explanations for this complex and somewhat protracted event are reviewed, with a focus on how well each explains the observed increases in disparity and diversity, the time of onset of the radiation, its duration, and its uniqueness. The increase in disparity (the origin of the phyla) and diversity are best understood as being the result of the interplay of the combinatorial bilaterian developmental system and the increase in the number of needs the first bilaterians had to meet as complex ecological interactions developed. The time of onset is constrained by the evolution of the environment, whereas its duration appears to be controlled primarily by rates of developmental innovation. The uniqueness of the event is either due to ensuing developmental limitation, to ecological saturation, or simply to the exhaustion of ecologically viable morphologies that could be produced by the nascent bilaterian developmental system.

  11. Explaining numeracy development in weak performing kindergartners.

    PubMed

    Toll, Sylke W M; Van Luit, Johannes E H

    2014-08-01

    Gaining better insight into precursors of early numeracy in young children is important, especially in those with inadequate numeracy skills. Therefore, in the current study, visual and verbal working memory, non-symbolic and symbolic comparison skills, and specific math-related language were used to explain early numeracy performance and development of weak performing children throughout kindergarten. The early numeracy ability of both weak performers and typical performers was measured at four time points during 2 years of kindergarten to compare growth rates. Results show a significant faster development of early numeracy in the weak performers. The development of weak performers' numeracy was influenced by verbal working memory, symbolic comparison skills, and math language, whereas only math language was positively related to the slope of typical performers' numeracy. In the weak performers, visual working memory, non-symbolic comparison skills, and math language showed an effect on the initial early numeracy level of these children. The intercept of the typical performers was predicted by five covariates, all except non-symbolic comparison. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Using and Explaining Individual Dosimetry Data.

    PubMed

    Miyazaki, Makoto

    2017-03-01

    Measurement of individual radiation dose is crucial for planning protective measures after nuclear accidents. The purpose of this article is to explain the various initiatives taken after the TEPCO Fukushima Daiichi Nuclear Power Plant accident, including the D-shuttle project wherein residents from affected areas wore a personal dosimeter to measure their own external exposure. The experience in Fukushima revealed several issues such as gaining residents' trust and ensuring appropriate communication of the measured data. The D-shuttle project also revealed that obtaining individual dose measurement data had 2 purposes, as the information obtained was to be utilized by the residents for self-protection and by the authorities for deriving the dose distribution of the population to aid in designing large-scale protection measures. The lessons learned are that both the residents and the authorities need to understand and share the meaning of individual dose measurements and the measurement results must be used with due respect for the residents' privacy and other concerns.

  13. Birdsong dialect patterns explained using magnetic domains

    NASA Astrophysics Data System (ADS)

    Burridge, James; Kenney, Steven

    2016-06-01

    The songs and calls of many bird species, like human speech, form distinct regional dialects. We suggest that the process of dialect formation is analogous to the physical process of magnetic domain formation. We take the coastal breeding grounds of the Puget Sound white crowned sparrow as an example. Previous field studies suggest that birds of this species learn multiple songs early in life, and when establishing a territory for the first time, retain one of these dialects in order to match the majority of their neighbors. We introduce a simple lattice model of the process, showing that this matching behavior can produce single dialect domains provided the death rate of adult birds is sufficiently low. We relate death rate to thermodynamic temperature in magnetic materials, and calculate the critical death rate by analogy with the Ising model. Using parameters consistent with the known behavior of these birds we show that coastal dialect domain shapes may be explained by viewing them as low-temperature "stripe states."

  14. Explaining clinical behaviors using multiple theoretical models.

    PubMed

    Eccles, Martin P; Grimshaw, Jeremy M; MacLennan, Graeme; Bonetti, Debbie; Glidewell, Liz; Pitts, Nigel B; Steen, Nick; Thomas, Ruth; Walker, Anne; Johnston, Marie

    2012-10-17

    In the field of implementation research, there is an increased interest in use of theory when designing implementation research studies involving behavior change. In 2003, we initiated a series of five studies to establish a scientific rationale for interventions to translate research findings into clinical practice by exploring the performance of a number of different, commonly used, overlapping behavioral theories and models. We reflect on the strengths and weaknesses of the methods, the performance of the theories, and consider where these methods sit alongside the range of methods for studying healthcare professional behavior change. These were five studies of the theory-based cognitions and clinical behaviors (taking dental radiographs, performing dental restorations, placing fissure sealants, managing upper respiratory tract infections without prescribing antibiotics, managing low back pain without ordering lumbar spine x-rays) of random samples of primary care dentists and physicians. Measures were derived for the explanatory theoretical constructs in the Theory of Planned Behavior (TPB), Social Cognitive Theory (SCT), and Illness Representations specified by the Common Sense Self Regulation Model (CSSRM). We constructed self-report measures of two constructs from Learning Theory (LT), a measure of Implementation Intentions (II), and the Precaution Adoption Process. We collected data on theory-based cognitions (explanatory measures) and two interim outcome measures (stated behavioral intention and simulated behavior) by postal questionnaire survey during the 12-month period to which objective measures of behavior (collected from routine administrative sources) were related. Planned analyses explored the predictive value of theories in explaining variance in intention, behavioral simulation and behavior. Response rates across the five surveys ranged from 21% to 48%; we achieved the target sample size for three of the five surveys. For the predictor variables

  15. Explaining clinical behaviors using multiple theoretical models

    PubMed Central

    2012-01-01

    Background In the field of implementation research, there is an increased interest in use of theory when designing implementation research studies involving behavior change. In 2003, we initiated a series of five studies to establish a scientific rationale for interventions to translate research findings into clinical practice by exploring the performance of a number of different, commonly used, overlapping behavioral theories and models. We reflect on the strengths and weaknesses of the methods, the performance of the theories, and consider where these methods sit alongside the range of methods for studying healthcare professional behavior change. Methods These were five studies of the theory-based cognitions and clinical behaviors (taking dental radiographs, performing dental restorations, placing fissure sealants, managing upper respiratory tract infections without prescribing antibiotics, managing low back pain without ordering lumbar spine x-rays) of random samples of primary care dentists and physicians. Measures were derived for the explanatory theoretical constructs in the Theory of Planned Behavior (TPB), Social Cognitive Theory (SCT), and Illness Representations specified by the Common Sense Self Regulation Model (CSSRM). We constructed self-report measures of two constructs from Learning Theory (LT), a measure of Implementation Intentions (II), and the Precaution Adoption Process. We collected data on theory-based cognitions (explanatory measures) and two interim outcome measures (stated behavioral intention and simulated behavior) by postal questionnaire survey during the 12-month period to which objective measures of behavior (collected from routine administrative sources) were related. Planned analyses explored the predictive value of theories in explaining variance in intention, behavioral simulation and behavior. Results Response rates across the five surveys ranged from 21% to 48%; we achieved the target sample size for three of the five surveys

  16. Punishments and Prizes for Explaining Global Warming

    NASA Astrophysics Data System (ADS)

    Somerville, R. C.

    2006-12-01

    Some few gifted scientists, the late Carl Sagan being an iconic example, are superbly skilled at communicating science clearly and compellingly to non-scientists. Most scientists, however, have serious shortcomings as communicators. The common failings include being verbose, addicted to jargon, caveat- obsessed and focused on details. In addition, it is far easier for a scientist to scoff at the scientific illiteracy of modern society than to work at understanding the viewpoints and concerns of journalists, policymakers and the public. Obstacles await even those scientists with the desire and the talent to communicate science well. Peer pressure and career disincentives can act as powerful deterrents, discouraging especially younger scientists from spending time on non-traditional activities. Scientists often lack mentors and role models to help them develop skills in science communication. Journalists also face real difficulties in getting science stories approved by editors and other gatekeepers. Climate change science brings its own problems in communication. The science itself is unusually wide- ranging and complex. The contentious policies and politics of dealing with global warming are difficult to disentangle from the science. Misinformation and disinformation about climate change are widespread. Intimidation and censorship of scientists by some employers is a serious problem. Polls show that global warming ranks low on the public's list of important issues. Despite all the obstacles, communicating climate change science well is critically important today. It is an art that can be learned and that brings its own rewards and satisfactions. Academic institutions and research funding agencies increasingly value outreach by scientists, and they provide resources to facilitate it. Society needs scientists who can clearly and authoritatively explain the science of global warming and its implications, while remaining objective and policy-neutral. This need will

  17. Explaining Counterfeit Alcohol Purchases in Russia.

    PubMed

    Kotelnikova, Zoya

    2017-04-01

    of surrogate alcohol (i.e., nonbeverage) are more influential in explaining why people purchase counterfeit alcohol. Further research on these 2 factors is needed to more fully understand the purchase and consumption of counterfeit alcoholic beverages. Copyright © 2017 by the Research Society on Alcoholism.

  18. Modeling factors explaining physicians’ satisfaction with competence

    PubMed Central

    Lepnurm, Rein; Dobson, Roy Thomas; Peña-Sánchez, Juan-Nicolás; Nesdole, Robert

    2015-01-01

    Recognition explained 60.2% of the variation in Satisfaction with Competence, controlling for years in practice, self-reported health and duties of physicians. Conclusion: Satisfaction with Competence could be affected by excessive accumulation of duties, concerns about quality, efficiency, access, excessive distress, inadequate coping abilities, personal satisfaction with life as a physician, challenges in managing practices and persistent inequities among physicians. PMID:27092256

  19. CAN PLANETARY INSTABILITY EXPLAIN THE KEPLER DICHOTOMY?

    SciTech Connect

    Johansen, Anders; Davies, Melvyn B.; Church, Ross P.; Holmelin, Viktor

    2012-10-10

    The planet candidates discovered by the Kepler mission provide a rich sample to constrain the architectures and relative inclinations of planetary systems within approximately 0.5 AU of their host stars. We use the triple-transit systems from the Kepler 16 months data as templates for physical triple-planet systems and perform synthetic transit observations, varying the internal inclination variation of the orbits. We find that all the Kepler triple-transit and double-transit systems can be produced from the triple-planet templates, given a low mutual inclination of around 5 Degree-Sign . Our analysis shows that the Kepler data contain a population of planets larger than four Earth radii in single-transit systems that cannot arise from the triple-planet templates. We explore the hypothesis that high-mass counterparts of the triple-transit systems underwent dynamical instability to produce a population of massive double-planet systems of moderately high mutual inclination. We perform N-body simulations of mass-boosted triple-planet systems and observe how the systems heat up and lose planets by planet-planet collisions, and less frequently by ejections or collisions with the star, yielding transits in agreement with the large planets in the Kepler single-transit systems. The resulting population of massive double-planet systems nevertheless cannot explain the additional excess of low-mass planets among the observed single-transit systems and the lack of gas-giant planets in double-transit and triple-transit systems. Planetary instability of systems of triple gas-giant planets can be behind part of the dichotomy between systems hosting one or more small planets and those hosting a single giant planet. The main part of the dichotomy, however, is more likely to have arisen already during planet formation when the formation, migration, or scattering of a massive planet, triggered above a threshold metallicity, suppressed the formation of other planets in sub-AU orbits.

  20. Modeling factors explaining physicians' satisfaction with competence.

    PubMed

    Lepnurm, Rein; Dobson, Roy Thomas; Peña-Sánchez, Juan-Nicolás; Nesdole, Robert

    2015-01-01

    Attention to physician wellness has increased as medical practice gains in complexity. Physician satisfaction with practice is critical for quality of care and practice growth. The purpose of this study was to model physicians' self-reported Satisfaction with Competence as a function of their perceptions of the Quality of Health Services, Distress, Coping, Practice Management, Personal Satisfaction and Professional Equity. Comprehensive questionnaires were sent to a stratified sample of 5300 physicians across Canada. This cross-sectional study focused on physicians who examined and treated individual patients for a final study population of 2639 physicians. Response bias was negligible. The questionnaires contained measures of Satisfaction with Competence, Quality of Health Services, Distress, Coping, Personal Satisfaction, Practice Management and Professional Equity. Exploring relationships was done using Pearson correlations and one-way analysis of variance. Modeling was by hierarchical regressions. The measures were reliable: Satisfaction with Competence (α = .86), Quality (α = .86), Access (α = .82), Distress (α = .82), Coping (α = .76), Personal Satisfaction (α = .78), Practice Management (α = .89) and the dimensions of Professional Equity (Fulfillment, α = .81; Financial, α = .93; and Recognition, α = .75) with comparative validity. Satisfaction with Competence was positively correlated with Quality (r = .32), Efficiency (r = .37) and Access (r = .32); negatively correlated with Distress (r = -.54); and positively correlated with Coping strategies (r = .43), Personal Satisfaction (r = .57), Practice Management (r = .17), Fulfillment (r = .53), Financial (r = .36) and Recognition (r = .54). Physicians' perceptions on Quality, Efficiency, Access, Distress, Coping, Personal Satisfaction, Practice Management, Fulfillment, Pay and Recognition explained 60.2% of the variation

  1. Explaining the Birth of the Martian Moons

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-09-01

    led to the formation of large clumps, which eventually agglomerated to form Phobos and Deimos.The authors find that Phobos and Deimos most likely formed in the outer regions of the accretion disk that was created by a large impact with Mars. [Adapted from Ronnet et al. 2016]In the study conducted by Ronnet, Vernazza, and collaborators, the authors investigated the composition and texture of the dust that would have crystallized in an impact-generated accretion disk making up Marss moons. They find that Phobos and Deimos could not have formed out of the extremely hot, magma-filled inner regions of such a disk, because this would have resulted in different compositions than we observe.Phobos and Deimos could have formed, however, in the very outer part of an impact-generated accretion disk, where the hot gas condensed directly into small solid grains instead of passing through the magma phase. Accretion of such tiny grains would naturally explain the similarity in physical properties we observe between Marss moons and some main-belt asteroids and yet this picture is also consistent with the moons current orbital parameters.The authors argue that the formation of the Martian moons from the outer regions of an impact-generated accretion disk is therefore a plausible scenario, neatly reconciling the observed physical properties of Phobos and Diemos with their orbital properties.CitationT. Ronnet et al 2016 ApJ 828 109. doi:10.3847/0004-637X/828/2/109

  2. Learning from Explaining: Does It Matter if Mom Is Listening?

    ERIC Educational Resources Information Center

    Rittle-Johnson, B.; Saylor, M.; Swygert, K.E.

    2008-01-01

    The goal of the current study was to examine whether explaining to another person improves learning and transfer. In the study, 4- and 5-year-olds (N=54) solved multiple classification problems, received accuracy feedback, and were prompted to explain the correct solutions to their moms, to explain the correct solutions to themselves, or to repeat…

  3. Learning from Explaining: Does It Matter if Mom Is Listening?

    ERIC Educational Resources Information Center

    Rittle-Johnson, B.; Saylor, M.; Swygert, K.E.

    2008-01-01

    The goal of the current study was to examine whether explaining to another person improves learning and transfer. In the study, 4- and 5-year-olds (N=54) solved multiple classification problems, received accuracy feedback, and were prompted to explain the correct solutions to their moms, to explain the correct solutions to themselves, or to repeat…

  4. Explaining and Communicating Science Using Student-Created Blended Media

    ERIC Educational Resources Information Center

    Hoban, Garry; Nielsen, Wendy; Shepherd, Alyce

    2013-01-01

    Students engage with science content when they are asked to explain and communicate their knowledge to others. In particular, encouraging students to create various digital media forms such as videos, podcasts, vodcasts, screencasts, digital stories and animations to explain science is usually engaging, especially if they have ownership of the…

  5. Explaining and Communicating Science Using Student-Created Blended Media

    ERIC Educational Resources Information Center

    Hoban, Garry; Nielsen, Wendy; Shepherd, Alyce

    2013-01-01

    Students engage with science content when they are asked to explain and communicate their knowledge to others. In particular, encouraging students to create various digital media forms such as videos, podcasts, vodcasts, screencasts, digital stories and animations to explain science is usually engaging, especially if they have ownership of the…

  6. Explaining Infinite Series--An Exploration of Students' Images

    ERIC Educational Resources Information Center

    Champney, Danielle Dawn

    2013-01-01

    This study uses self-generated representations (SGR)--images produced in the act of explaining--as a means of uncovering what university calculus students understand about infinite series convergence. It makes use of student teaching episodes, in which students were asked to explain to a peer what that student might have missed had they been…

  7. Explaining Infinite Series--An Exploration of Students' Images

    ERIC Educational Resources Information Center

    Champney, Danielle Dawn

    2013-01-01

    This study uses self-generated representations (SGR)--images produced in the act of explaining--as a means of uncovering what university calculus students understand about infinite series convergence. It makes use of student teaching episodes, in which students were asked to explain to a peer what that student might have missed had they been…

  8. Exploring the explaining quality of physics online explanatory videos

    NASA Astrophysics Data System (ADS)

    Kulgemeyer, Christoph; Peters, Cord H.

    2016-11-01

    Explaining skills are among the most important skills educators possess. Those skills have also been researched in recent years. During the same period, another medium has additionally emerged and become a popular source of information for learners: online explanatory videos, chiefly from the online video sharing website YouTube. Their content and explaining quality remain to this day mostly unmonitored, as well is their educational impact in formal contexts such as schools or universities. In this study, a framework for explaining quality, which has emerged from surveying explaining skills in expert-novice face-to-face dialogues, was used to explore the explaining quality of such videos (36 YouTube explanatory videos on Kepler’s laws and 15 videos on Newton’s third law). The framework consists of 45 categories derived from physics education research that deal with explanation techniques. YouTube provides its own ‘quality measures’ based on surface features including ‘likes’, views, and comments for each video. The question is whether or not these measures provide valid information for educators and students if they have to decide which video to use. We compared the explaining quality with those measures. Our results suggest that there is a correlation between explaining quality and only one of these measures: the number of content-related comments.

  9. Explainable expert systems: A research program in information processing

    NASA Technical Reports Server (NTRS)

    Paris, Cecile L.

    1993-01-01

    Our work in Explainable Expert Systems (EES) had two goals: to extend and enhance the range of explanations that expert systems can offer, and to ease their maintenance and evolution. As suggested in our proposal, these goals are complementary because they place similar demands on the underlying architecture of the expert system: they both require the knowledge contained in a system to be explicitly represented, in a high-level declarative language and in a modular fashion. With these two goals in mind, the Explainable Expert Systems (EES) framework was designed to remedy limitations to explainability and evolvability that stem from related fundamental flaws in the underlying architecture of current expert systems.

  10. Genes May Explain Why Kids with Autism Avoid Eye Contact

    MedlinePlus

    ... May Explain Why Kids With Autism Avoid Eye Contact More research could shed light on how these ... with autism spectrum disorders tend to avoid eye contact and look away from other people's mouths, behaviors ...

  11. Limit Cycles Can Explain Fluvial Features on Early Mars

    NASA Astrophysics Data System (ADS)

    Haqq-Misra, J.; Batalha, N. E.; Kopparapu, R. K.; Kadoya, S.; Kasting, J. F.

    2017-10-01

    We argue that the presence of fluvial features on early Mars can be explained from limit cycles of global glaciation and deglaciation that occurred through modulation of CO2 by the carbonate-silicate cycle under a faint young sun.

  12. Using Plant Functional Traits to Explain Diversity–Productivity Relationships

    PubMed Central

    Roscher, Christiane; Schumacher, Jens; Gubsch, Marlén; Lipowsky, Annett; Weigelt, Alexandra; Buchmann, Nina; Schmid, Bernhard; Schulze, Ernst-Detlef

    2012-01-01

    Background The different hypotheses proposed to explain positive species richness–productivity relationships, i.e. selection effect and complementarity effect, imply that plant functional characteristics are at the core of a mechanistic understanding of biodiversity effects. Methodology/Principal Findings We used two community-wide measures of plant functional composition, (1) community-weighted means of trait values (CWM) and (2) functional trait diversity based on Rao’s quadratic diversity (FDQ) to predict biomass production and measures of biodiversity effects in experimental grasslands (Jena Experiment) with different species richness (2, 4, 8, 16 and 60) and different functional group number and composition (1 to 4; legumes, grasses, small herbs, tall herbs) four years after establishment. Functional trait composition had a larger predictive power for community biomass and measures of biodiversitity effects (40–82% of explained variation) than species richness per se (<1–13% of explained variation). CWM explained a larger amount of variation in community biomass (80%) and net biodiversity effects (70%) than FDQ (36 and 38% of explained variation respectively). FDQ explained similar proportions of variation in complementarity effects (24%, positive relationship) and selection effects (28%, negative relationship) as CWM (27% of explained variation for both complementarity and selection effects), but for all response variables the combination of CWM and FDQ led to significant model improvement compared to a separate consideration of different components of functional trait composition. Effects of FDQ were mainly attributable to diversity in nutrient acquisition and life-history strategies. The large spectrum of traits contributing to positive effects of CWM on biomass production and net biodiversity effects indicated that effects of dominant species were associated with different trait combinations. Conclusions/Significance Our results suggest that the

  13. Explaining ethnic disparities in preterm birth in Argentina and Ecuador.

    PubMed

    Wehby, George L; Pawluk, Mariela; Nyarko, Kwame A; López-Camelo, Jorge S

    2016-11-22

    Little is understood about racial/ethnic disparities in infant health in South America. We quantified the extent to which the disparity in preterm birth (PTB; <37 gestational weeks) rate between infants of Native only ancestry and those of European only ancestry in Argentina and Ecuador are explained by household socio-economic, demographic, healthcare use, and geographic location indicators. The samples included 5199 infants born between 2000 and 2011 from Argentina and 1579 infants born between 2001 and 2011 from Ecuador. An Oaxaca-Blinder type decomposition model adapted to binary outcomes was estimated to explain the disparity in PTB risk across groups of variables and specific variables. Maternal use of prenatal care services significantly explained the PTB disparity, by nearly 57% and 30% in Argentina and Ecuador, respectively. Household socio-economic status explained an additional 26% of the PTB disparity in Argentina. Differences in maternal use of prenatal care may partly explain ethnic disparities in PTB in Argentina and Ecuador. Improving access to prenatal care may reduce ethnic disparities in PTB risk in these countries.

  14. Explaining social class differences in depression and well-being.

    PubMed

    Stansfeld, S A; Head, J; Marmot, M G

    1998-01-01

    Work characteristics, including skill discretion and decision authority, explain most of the socioeconomic status gradient in well-being and depression in middle-aged British civil servants from the Whitehall II Study, London. Social support explained about one-third of the gradient, life events and material difficulties less than one-third. Socioeconomic status was measured by employment grade. Work characteristics were based on the Karasek model, social support was measured by the Close Persons Questionnaire, depression by the General Health Questionnaire and well-being by the Affect Balance Scale. Despite a small contribution from social selective factors measured by upward mobility, the psychosocial work environment explained most of the cross-sectional socioeconomic status gradient in well-being and depression.

  15. Explaining patterns in the ratification of global environmental treaties

    NASA Technical Reports Server (NTRS)

    Cook, David W.

    1991-01-01

    A study was made of the ratification behavior of 160 countries with respect to 38 global environmental treaties. The study identifies and explains patterns in the ratification of treaties, providing two means of assessing the likelihood that any given country will support global environmental treaties. National ratification totals reveal a pattern of high ratification by countries in Western Europe, North America, Japan, Australia, and New Zealand. A country's standing within the range of high to low ratification rates can be explained by the statistical model developed in the study. This research allows one to identify countries likely to support global environmental treaties.

  16. EXPLAINING THE MOTHERHOOD WAGE PENALTY DURING THE EARLY OCCUPATIONAL CAREER

    PubMed Central

    STAFF, JEREMY; MORTIMER, JEYLAN T.

    2011-01-01

    Prior research shows that mothers earn lower hourly wages than women without children, and that this maternal wage penalty cannot be fully explained by differences between mothers and other women in work experience and job characteristics. This research examines whether the residual motherhood wage penalty results from differences between mothers and other women in the accumulation of work interruptions and breaks in schooling. Using longitudinal data for 486 women followed from ages 19 to 31 in the Youth Development Study, we find that accumulated months not in the labor force and not enrolled in school explain the residual pay gap between mothers and other women. PMID:22037996

  17. Explaining the motherhood wage penalty during the early occupational career.

    PubMed

    Staff, Jeremy; Mortimer, Jeylan T

    2012-02-01

    Prior research shows that mothers earn lower hourly wages than women without children, and that this maternal wage penalty cannot be fully explained by differences between mothers and other women in work experience and job characteristics. This research examines whether the residual motherhood wage penalty results from differences between mothers and other women in the accumulation of work interruptions and breaks in schooling. Using longitudinal data for 486 women followed from ages 19 to 31 in the Minnesota Youth Development Study, we find that accumulated months not in the labor force and not enrolled in school explain the residual pay gap between mothers and other women.

  18. "Let Me Explain": Students as Colonial History Docents.

    ERIC Educational Resources Information Center

    Gesek, Linda L.

    2000-01-01

    Explains that there are four levels of involvement for introducing students to the skills of docents. Describes a docent program, an extracurricular activity provided at Montgomery High School in Skillman, New Jersey, in which students are docents at the Rockingham Historic Site. Discusses the benefits of such a program. (CMK)

  19. Explaining the forest product selling behavior of private woodland owners

    Treesearch

    David N. Larsen; David A. Gansner; David A. Gansner

    1973-01-01

    A multiple-variable screening technique, AID, was used to explain the forest-product-sales behavior of private woodland owners. Results provide a basis for policy-related inferences and suggest an optimal strategy for encouraging sales of forest products.

  20. Explaining Success and Failure: Counterinsurgency in Malaya and India

    DTIC Science & Technology

    2010-12-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS EXPLAINING SUCCESS AND FAILURE: COUNTERINSURGENCY IN MALAYA AND INDIA by...considerable Naxalite communist militant activity. These are also areas that suffer from the greatest illiteracy, poverty and overpopulation in modern...Komer, The Malayan Emergency in Retrospect: Organization of a Successful Counterinsurgency Effort ( California : RAND, 1972), 17–22. 49

  1. Students Explaining Science—Assessment of Science Communication Competence

    NASA Astrophysics Data System (ADS)

    Kulgemeyer, Christoph; Schecker, Horst

    2013-12-01

    Science communication competence (SCC) is an important educational goal in the school science curricula of several countries. However, there is a lack of research about the structure and the assessment of SCC. This paper specifies the theoretical framework of SCC by a competence model. We developed a qualitative assessment method for SCC that is based on an expert-novice dialog: an older student (explainer, expert) explains a physics phenomenon to a younger peer (addressee, novice) in a controlled test setting. The explanations are video-recorded and analysed by qualitative content analysis. The method was applied in a study with 46 secondary school students as explainers. Our aims were (a) to evaluate whether our model covers the relevant features of SCC, (b) to validate the assessment method and (c) to find characteristics of addressee-adequate explanations. A performance index was calculated to quantify the explainers' levels of competence on an ordinal scale. We present qualitative and quantitative evidence that the index is adequate for assessment purposes. It correlates with results from a written SCC test and a perspective taking test (convergent validity). Addressee-adequate explanations can be characterized by use of graphical representations and deliberate switches between scientific and everyday language.

  2. Visualisation and Reasoning in Explaining the Phases of the Moon

    ERIC Educational Resources Information Center

    Subramaniam, K.; Padalkar, Shamin

    2009-01-01

    In this study, we examine how subjects set up, transform, and reason with models that they establish on the basis of known facts as they seek to explain a familiar everyday phenomenon--the phases of the moon. An interview schedule was designed to elicit subjects' reasoning, and in the case where explanations were mistaken, to induce a change in…

  3. The Role of Secondary Education in Explaining Competitiveness

    ERIC Educational Resources Information Center

    Baumann, Chris; Winzar, Hume

    2016-01-01

    The literature establishes that education drives economic performance, but the extent that education is associated with a country's competitiveness is empirically untested. Our study analyses Programme for International Student Assessment (PISA) data from 63 countries to ascertain education's role in explaining the competitiveness of a country.…

  4. Using Physical Models to Explain a Division Algorithm.

    ERIC Educational Resources Information Center

    Vest, Floyd

    1985-01-01

    Develops a division algorithm in terms of familiar manipulations of concrete objects and presents it with a series of questions for diagnosis of students' understanding of the algorithm in terms of the concrete model utilized. Also offers general guidelines for using concrete illustrations to explain algorithms and other mathematical principles.…

  5. Explaining Common Variance Shared by Early Numeracy and Literacy

    ERIC Educational Resources Information Center

    Davidse, N. J.; De Jong, M. T.; Bus, A. G.

    2014-01-01

    How can it be explained that early literacy and numeracy share variance? We specifically tested whether the correlation between four early literacy skills (rhyming, letter knowledge, emergent writing, and orthographic knowledge) and simple sums (non-symbolic and story condition) reduced after taking into account preschool attention control,…

  6. Understanding Electrochemistry Concepts Using the Predict-Observe-Explain Strategy

    ERIC Educational Resources Information Center

    Karamustafaoglu, Sevilay; Mamlok-Naaman, Rachel

    2015-01-01

    The current study deals with freshman students who study at the Department of Science at the Faculty of Education. The aim of the study was to investigate the effect of teaching electrochemistry concepts using Predict-Observe-Explain (POE) strategy. The study was quasi-experimental design using 20 students each in the experimental group (EG) and…

  7. Violence and Institutionalization in Islamic Activism: Explaining Moderation

    DTIC Science & Technology

    2006-12-01

    purportedly free from corruption and Western influence.4 2 Abdo Baaklini, Guilain Denoeux, and... CT : Yale University Press, 1998, 85-86. 35 Pew Research, 2. 12 2. Major Argument What explains the willingness of Islamist groups, like the...Lebanon into 14 constituencies and crossed sectarian boundaries. As a result, the groups 82 Abdo

  8. Explaining University Students' Effective Use of E-Learning Platforms

    ERIC Educational Resources Information Center

    Moreno, Valter; Cavazotte, Flavia; Alves, Isabela

    2017-01-01

    Students' success in e-learning programs depends on how they adopt and embed technology into their learning activities. Drawing on the Technology Acceptance Model, we propose a framework to explain students' intention to use e-learning platforms effectively, that is, their intention to fully exploit system's functionalities in leaning processes,…

  9. Generalizing MOND to explain the missing mass in galaxy clusters

    NASA Astrophysics Data System (ADS)

    Hodson, Alistair O.; Zhao, Hongsheng

    2017-02-01

    Context. MOdified Newtonian Dynamics (MOND) is a gravitational framework designed to explain the astronomical observations in the Universe without the inclusion of particle dark matter. MOND, in its current form, cannot explain the missing mass in galaxy clusters without the inclusion of some extra mass, be it in the form of neutrinos or non-luminous baryonic matter. We investigate whether the MOND framework can be generalized to account for the missing mass in galaxy clusters by boosting gravity in high gravitational potential regions. We examine and review Extended MOND (EMOND), which was designed to increase the MOND scale acceleration in high potential regions, thereby boosting the gravity in clusters. Aims: We seek to investigate galaxy cluster mass profiles in the context of MOND with the primary aim at explaining the missing mass problem fully without the need for dark matter. Methods: Using the assumption that the clusters are in hydrostatic equilibrium, we can compute the dynamical mass of each cluster and compare the result to the predicted mass of the EMOND formalism. Results: We find that EMOND has some success in fitting some clusters, but overall has issues when trying to explain the mass deficit fully. We also investigate an empirical relation to solve the cluster problem, which is found by analysing the cluster data and is based on the MOND paradigm. We discuss the limitations in the text.

  10. Do Sheepskin Effects Help Explain Racial Earnings Differences?

    ERIC Educational Resources Information Center

    Bitzan, John D.

    2009-01-01

    This study examines the role of sheepskin effects in explaining white-black earnings differences. The study finds significant differences in sheepskin effects between white men and black men, with white men receiving higher rewards for lower level signals (degrees of a college education or less) and black men receiving higher rewards for higher…

  11. Explaining the Effects of Communities of Pastoral Care for Students

    ERIC Educational Resources Information Center

    Murphy, Joseph; Holste, Linda

    2016-01-01

    This article explains how communities of pastoral care work. It presents an empirically forged theory in action. We examined theoretical and empirical work across the targeted area of personalization for students. We also completed what Hallinger (2012) refers to as "exhaustive review" of the field of school improvement writ large. We…

  12. A social cognitive perspective on 'understanding' and 'explaining'.

    PubMed

    Vogeley, Kai

    2013-01-01

    One essential methodological dichotomy introduced by Karl Jaspers into the field of psychopathology is the difference between 'understanding' ('Verstehen') and 'explaining' ('Erklären'). Jaspers emphasizes a critical epistemological divide between both methods: whereas 'explaining' relates to the attempt to consider mental disorders as consequences of impersonal natural laws, 'understanding' refers to the empathic appreciation of conflicts, hopes, and desires of an individual person. This distinction is related to the difference between 'persons' and 'things' according to Fritz Heider, founder of the so-called 'attribution theory' in social psychology that deals with our ability to ascribe mental states to others. Whereas the behavior of persons is based on psychological rules that are inherently characterized by ambiguity and uncertainty and are thus only partly predictable, the behavior of things is based on natural laws and is therefore fully predictable. This suggests a close resemblance of both accounts where 'understanding' is related to the domain of persons and 'explaining' is related to the domain of things or physical objects. Recently, understanding others has also become a central topic of modern cognitive neuroscience, constituting 'social neuroscience' targeted at explaining our human capacity of ascribing mental states to others. This shows that this distinction introduced by Jaspers still is an important and fundamental differentiation for various research fields dealing with communication and interaction between persons. © 2013 S. Karger AG, Basel.

  13. The Role of Secondary Education in Explaining Competitiveness

    ERIC Educational Resources Information Center

    Baumann, Chris; Winzar, Hume

    2016-01-01

    The literature establishes that education drives economic performance, but the extent that education is associated with a country's competitiveness is empirically untested. Our study analyses Programme for International Student Assessment (PISA) data from 63 countries to ascertain education's role in explaining the competitiveness of a country.…

  14. Explaining Learning: From Analysis to Paralysis to Hippocampus

    ERIC Educational Resources Information Center

    Clark, John

    2005-01-01

    This paper seeks to explain learning by examining five theories of learning--conceptual analysis, behavioural, constructivist, computational and connectionist. The first two are found wanting and rejected. Piaget's constructivist theory offers a general explanatory framework (assimilation and accommodation) but fails to provide an adequate account…

  15. Explaining Recent Army and Navy Minority Recruiting Trends. Research Brief

    ERIC Educational Resources Information Center

    Steinberg, Paul

    2009-01-01

    Between 2000 and 2007, the representation of blacks among high-quality Army recruits declined, while in the Navy, black representation remained stable; the representation of Hispanics among high-quality recruits in both the Army and Navy grew during this period. RAND researchers identified factors that explain these recruiting trends and found…

  16. Do Sheepskin Effects Help Explain Racial Earnings Differences?

    ERIC Educational Resources Information Center

    Bitzan, John D.

    2009-01-01

    This study examines the role of sheepskin effects in explaining white-black earnings differences. The study finds significant differences in sheepskin effects between white men and black men, with white men receiving higher rewards for lower level signals (degrees of a college education or less) and black men receiving higher rewards for higher…

  17. A Quest to Explain the Extreme Realism in Newbery Books

    ERIC Educational Resources Information Center

    Miguez, Betsy Bryan; Goetting, Denise

    2006-01-01

    The quest to explain the extreme realism found in some Newbery Award books led the authors to discover that there is no unified view of childhood affecting children's literature today. While some adults feel that children must be protected against the evil surrounding them, others feel that they must be prepared to face the world in which they…

  18. Can Input Explain Children's Me-for-I Errors?

    ERIC Educational Resources Information Center

    Kirjavainen, Minna; Theakston, Anna; Lieven, Elena

    2009-01-01

    English-speaking children make pronoun case errors producing utterances where accusative pronouns are used in nominative contexts ("me do it"). We investigate whether complex utterances in the input ("Let me do it") might explain the origin of these errors. Longitudinal naturalistic data from seventeen English-speaking two- to four-year-olds was…

  19. Teacher Styles in Questioning and Explaining. Technical Report No. 39.

    ERIC Educational Resources Information Center

    Moore, Carol Ann

    The primary purpose of this study was to identify and describe individual differences in teaching style (i.e., teachers' patterns of questioning and explaining) in a standardized teaching situation. The secondary purpose was to explore relationships between teaching behavior and other teacher characteristics: teaching experience; sex and selected…

  20. Explaining Common Variance Shared by Early Numeracy and Literacy

    ERIC Educational Resources Information Center

    Davidse, N. J.; De Jong, M. T.; Bus, A. G.

    2014-01-01

    How can it be explained that early literacy and numeracy share variance? We specifically tested whether the correlation between four early literacy skills (rhyming, letter knowledge, emergent writing, and orthographic knowledge) and simple sums (non-symbolic and story condition) reduced after taking into account preschool attention control,…

  1. Understanding Electrochemistry Concepts Using the Predict-Observe-Explain Strategy

    ERIC Educational Resources Information Center

    Karamustafaoglu, Sevilay; Mamlok-Naaman, Rachel

    2015-01-01

    The current study deals with freshman students who study at the Department of Science at the Faculty of Education. The aim of the study was to investigate the effect of teaching electrochemistry concepts using Predict-Observe-Explain (POE) strategy. The study was quasi-experimental design using 20 students each in the experimental group (EG) and…

  2. Children's Understanding of Substances, Part 2: Explaining Chemical Change.

    ERIC Educational Resources Information Center

    Johnson, Philip

    2002-01-01

    Focuses on the idea of chemical change and reports data from a study exploring the development of the concept of substance in children aged 11-14. Examines the use of the idea of elements, compounds, and bonding between atoms to explain chemical change and the intersection of these ideas with "basic" particle ideas. (Contains 21 references.)…

  3. Learning to Apply Models of Materials While Explaining Their Properties

    ERIC Educational Resources Information Center

    Karpin, Tiia; Juuti, Kalle; Lavonen, Jari

    2014-01-01

    Background: Applying structural models is important to chemistry education at the upper secondary level, but it is considered one of the most difficult topics to learn. Purpose: This study analyses to what extent in designed lessons students learned to apply structural models in explaining the properties and behaviours of various materials.…

  4. The Role of an Educational Learning Theory: Explaining Difficult Learning.

    ERIC Educational Resources Information Center

    Bereiter, Carl

    The possibility of developing a learning theory that is designed to insure its relevance to educational problems is discussed. It is suggested that the constitutive problem for an educational psychology of learning is how one learns things that are difficult to learn. Behaviorist learning theories fail almost entirely to explain why anything is…

  5. What Educators Need to Explain to the Public

    ERIC Educational Resources Information Center

    Rich, Dorothy

    2005-01-01

    Education is complex, slow, and demands teamwork. This is what educators need to be able to explain and what the public needs to understand. This is not getting across in the headlines. It is the author's experience that we have at least three categories of wrong ideas and half truths circulating around education: assumptions that mislead,…

  6. Explaining the Effects of Communities of Pastoral Care for Students

    ERIC Educational Resources Information Center

    Murphy, Joseph; Holste, Linda

    2016-01-01

    This article explains how communities of pastoral care work. It presents an empirically forged theory in action. We examined theoretical and empirical work across the targeted area of personalization for students. We also completed what Hallinger (2012) refers to as "exhaustive review" of the field of school improvement writ large. We…

  7. Using Culture to Explain Behavior: An Integrative Cultural Approach

    ERIC Educational Resources Information Center

    Shepherd, Hana R.; Stephens, Nicole M.

    2010-01-01

    While savings rates among low-income families vary greatly, a 2008 National Poverty Center report finds that over 40 percent of low-income families fail to save any money. For decades policy makers and social scientists have sought to explain this phenomenon. Even after accounting for the fact that low-income families have less money to save, why…

  8. Thermally-assisted Magma Emplacement Explains Restless Calderas.

    PubMed

    Amoruso, Antonella; Crescentini, Luca; D'Antonio, Massimo; Acocella, Valerio

    2017-08-11

    Many calderas show repeated unrest over centuries. Though probably induced by magma, this unique behaviour is not understood and its dynamics remains elusive. To better understand these restless calderas, we interpret deformation data and build thermal models of Campi Flegrei caldera, Italy. Campi Flegrei experienced at least 4 major unrest episodes in the last decades. Our results indicate that the inflation and deflation of magmatic sources at the same location explain most deformation, at least since the build-up of the last 1538 AD eruption. However, such a repeated magma emplacement requires a persistently hot crust. Our thermal models show that this repeated emplacement was assisted by the thermal anomaly created by magma that was intruded at shallow depth ~3 ka before the last eruption. This may explain the persistence of the magmatic sources promoting the restless behaviour of the Campi Flegrei caldera; moreover, it explains the crystallization, re-melting and mixing among compositionally distinct magmas recorded in young volcanic rocks. Our model of thermally-assisted unrest may have a wider applicability, possibly explaining also the dynamics of other restless calderas.

  9. Explaining the Socio-Economic Status School Completion Gap

    ERIC Educational Resources Information Center

    Polidano, Cain; Hanel, Barbara; Buddelmeyer, Hielke

    2013-01-01

    Relatively low rates of school completion among students from low socio-economic backgrounds is a key driver of intergenerational inequality. Linking data from the Programme for International Student Assessment with data from the Longitudinal Survey of Australian Youth, we use a decomposition framework to explain the gap in school completion rates…

  10. Explaining Test Results to Parents. ERIC Digest Number 102.

    ERIC Educational Resources Information Center

    Eissenberg, Thomas E.; Rudner, Lawrence M.

    Guidelines for explaining standardized test results to parents of students are provided. More specifically, the guidelines cover rationales for testing, the various types of scores and their meanings, and means of interpreting scores. Scores covered include stanine scores, percentile scores, and grade-level equivalent scores. The importance to…

  11. Explaining the Socio-Economic Status School Completion Gap

    ERIC Educational Resources Information Center

    Polidano, Cain; Hanel, Barbara; Buddelmeyer, Hielke

    2013-01-01

    Relatively low rates of school completion among students from low socio-economic backgrounds is a key driver of intergenerational inequality. Linking data from the Programme for International Student Assessment with data from the Longitudinal Survey of Australian Youth, we use a decomposition framework to explain the gap in school completion rates…

  12. What Educators Need to Explain to the Public

    ERIC Educational Resources Information Center

    Rich, Dorothy

    2005-01-01

    Education is complex, slow, and demands teamwork. This is what educators need to be able to explain and what the public needs to understand. This is not getting across in the headlines. It is the author's experience that we have at least three categories of wrong ideas and half truths circulating around education: assumptions that mislead,…

  13. Children's Understanding of Substances, Part 2: Explaining Chemical Change.

    ERIC Educational Resources Information Center

    Johnson, Philip

    2002-01-01

    Focuses on the idea of chemical change and reports data from a study exploring the development of the concept of substance in children aged 11-14. Examines the use of the idea of elements, compounds, and bonding between atoms to explain chemical change and the intersection of these ideas with "basic" particle ideas. (Contains 21 references.)…

  14. Explaining Differences in Mental Health between Married and Cohabiting Individuals

    ERIC Educational Resources Information Center

    Marcussen, Kristen

    2005-01-01

    Research on the relationship between cohabitation and mental health tends to ignore social psychological factors that help explain mental health differences between the married and the unmarried, including coping resources and perceived relationship quality. In this paper I draw on social psychological theory and research to clarify differences in…

  15. Economic Models to Explain School Board Expenditures in Ontario.

    ERIC Educational Resources Information Center

    Lawton, Stephen B.

    1985-01-01

    Explains variations in per pupil expenditures among school boards in Ontario, Canada, using the "median voter model," which compares consumer behavior with government funding actions. With an inequitable tax price an important policy variable, the school grant program needs redesigning to achieve equity without sacrificing efficiency.…

  16. Explaining educational disparities in adiposity: the role of neighborhood environments.

    PubMed

    Abbott, Gavin; Backholer, Kathryn; Peeters, Anna; Thornton, Lukar; Crawford, David; Ball, Kylie

    2014-11-01

    To examine the extent to which characteristics of the neighborhood built environment explain the association between adiposity and educational qualifications in Australian women. A community sample of 1,819 women (aged 18-66) from the Melbourne SESAW study provided information regarding their body mass index (BMI) and level of education. Objective measures of participants' residential neighborhood built environments were obtained using a Geographic Information System. Compared with women with a high school degree or above, women who did not complete high school had higher average BMI, which was partially explained by lower density of sports facilities and living less proximally to the coastline and to supermarkets. In a multiple mediator model, which explained 16.6% of the educational disparity in BMI, the number of sports facilities and presence of the coastline within 2 km of participants' homes were significant mediators of the observed socioeconomic disparity in BMI. The residential neighborhood environment may help to explain socioeconomic patterning of overweight and obesity in Australian women. These results provide further support for considering the built environment in obesity prevention initiatives, suggesting a potential role in decreasing social inequalities in obesity. © 2014 The Obesity Society.

  17. Analysis and Assessment of Students' Competency to Explain Geographical Processes

    ERIC Educational Resources Information Center

    Dulama, Maria-Eliza; Alexandru, Diana-Elena

    2010-01-01

    In this study we seek to analyse the ability of students to explain, exemplify and outline geographical processes, as well as to assess their competencies by using an evaluation grid. Therefore, we tested two types of hypotheses. The first one regards the fact that it becomes more difficult for students to represent a previously learned…

  18. The Effect of Self-Explaining on Robust Learning

    ERIC Educational Resources Information Center

    Hausmann, Robert G. M.; VanLehn, Kurt

    2010-01-01

    Self-explaining is a domain-independent learning strategy that generally leads to a robust understanding of the domain material. However, there are two potential explanations for its effectiveness. First, self-explanation generates additional "content" that does not exist in the instructional materials. Second, when compared to…

  19. Using Culture to Explain Behavior: An Integrative Cultural Approach

    ERIC Educational Resources Information Center

    Shepherd, Hana R.; Stephens, Nicole M.

    2010-01-01

    While savings rates among low-income families vary greatly, a 2008 National Poverty Center report finds that over 40 percent of low-income families fail to save any money. For decades policy makers and social scientists have sought to explain this phenomenon. Even after accounting for the fact that low-income families have less money to save, why…

  20. Visualisation and Reasoning in Explaining the Phases of the Moon

    ERIC Educational Resources Information Center

    Subramaniam, K.; Padalkar, Shamin

    2009-01-01

    In this study, we examine how subjects set up, transform, and reason with models that they establish on the basis of known facts as they seek to explain a familiar everyday phenomenon--the phases of the moon. An interview schedule was designed to elicit subjects' reasoning, and in the case where explanations were mistaken, to induce a change in…

  1. Using Metaphors to Explain Molecular Testing to Cancer Patients.

    PubMed

    Pinheiro, Ana P M; Pocock, Rachel H; Dixon, Margie D; Shaib, Walid L; Ramalingam, Suresh S; Pentz, Rebecca D

    2017-04-01

    Molecular testing to identify targetable molecular alterations is routine practice for several types of cancer. Explaining the underlying molecular concepts can be difficult, and metaphors historically have been used in medicine to provide a common language between physicians and patients. Although previous studies have highlighted the use and effectiveness of metaphors to help explain germline genetic concepts to the general public, this study is the first to describe the use of metaphors to explain molecular testing to cancer patients in the clinical setting. Oncologist-patient conversations about molecular testing were recorded, transcribed verbatim, and coded. If a metaphor was used, patients were asked to explain it and assess its helpfulness. Sixty-six patients participated. Nine oncologists used metaphors to describe molecular testing; 25 of 66 (38%) participants heard a metaphor, 13 of 25 (52%) were questioned, 11 of 13 (85%) demonstrated understanding and reported the metaphor as being useful. Seventeen metaphors (bus driver, boss, switch, battery, circuit, broken light switch, gas pedal, key turning off an engine, key opening a lock, food for growth, satellite and antenna, interstate, alternate circuit, traffic jam, blueprint, room names, Florida citrus) were used to explain eight molecular testing terms (driver mutations, targeted therapy, hormones, receptors, resistance, exon specificity, genes, and cancer signatures). Because metaphors have proven to be a useful communication tool in other settings, these 17 metaphors may be useful for oncologists to adapt to their own setting to explain molecular testing terms. The Oncologist 2017;22:445-449Implications for Practice: This article provides a snapshot of 17 metaphors that proved useful in describing 8 complicated molecular testing terms at 3 sites. As complex tumor sequencing becomes standard of care in clinics and widely used in clinical research, the use of metaphors may prove a useful communication

  2. Factors explaining children's responses to intravenous needle insertions.

    PubMed

    McCarthy, Ann Marie; Kleiber, Charmaine; Hanrahan, Kirsten; Zimmerman, M Bridget; Westhus, Nina; Allen, Susan

    2010-01-01

    Previous research shows that numerous child, parent, and procedural variables affect children's distress responses to procedures. Cognitive-behavioral interventions such as distraction are effective in reducing pain and distress for many children undergoing these procedures. The purpose of this report was to examine child, parent, and procedural variables that explain child distress during a scheduled intravenous insertion when parents are distraction coaches for their children. A total of 542 children, between 4 and 10 years of age, and their parents participated. Child age, gender, diagnosis, and ethnicity were measured by questions developed for this study. Standardized instruments were used to measure child experience with procedures, temperament, ability to attend, anxiety, coping style, and pain sensitivity. Questions were developed to measure parent variables, including ethnicity, gender, previous experiences, and expectations, and procedural variables, including use of topical anesthetics and difficulty of procedure. Standardized instruments were used to measure parenting style and parent anxiety, whereas a new instrument was developed to measure parent performance of distraction. Children's distress responses were measured with the Observation Scale of Behavioral Distress-Revised (behavioral), salivary cortisol (biological), Oucher Pain Scale (self-report), and parent report of child distress (parent report). Regression methods were used for data analyses. Variables explaining behavioral, child-report and parent-report measures include child age, typical coping response, and parent expectation of distress (p < .01). Level of parents' distraction coaching explained a significant portion of behavioral, biological, and parent-report distress measures (p < .05). Child impulsivity and special assistance at school also significantly explained child self-report of pain (p < .05). Additional variables explaining cortisol response were child's distress in the

  3. What it Needs to Make Plant Function Explainable

    NASA Astrophysics Data System (ADS)

    Joswig, J. S.; Reu, B.; Wirth, C.; Richter, R.; Kattge, J.; Mahecha, M. D.

    2016-12-01

    Broad biogeographic patterns of plant trait identity and diversity across large spatial scales are strongly related to and shaped by environmental drivers. Hence, estimations of plant function from environmental drivers bear many promises for a better understanding of biospheric responses to global change. We assess requirements in terms of information needed to make plant traits predictable. Therefore we link plant trait data (TRY, www.try-db.org) to atmosphere (EarthSystemDataCube, earthsystemdatacube.net) and soil data (ISRIC, www.isric.org), then the environmental factors are selected for each trait (partial least square regression). We analyze i) the numbers of predictors, ii) the type of relationship and iii) the relative importance of atmospheric and soil factors. Our study shows that the environmental filter acts on trait identity and diversity in various ways. Trait identity is mostly better explicable than trait diversity. Trait identities, which are well explained relative to their number of predictors were most seed traits, leaf traits, except for nutrient related traits and plant height. For the trait diversities the best explained ones were most seed traits, LDMC and plant height. The environmental drivers are most relevant when included as non-linear and envelope variables for both trait identity and diversity. Overall, atmospheric factors explained trait identity and diversity better than soil-related predictors. Leaf and seed traits, are least explained by soil-related predictors. Stem traits, however, in comparison are explained by the greatest share of soil predictors. The present study aims to refine the picture of environmental filtering for plant traits, while it points to chances and missing information when it comes to predicting functional identity and diversity with an unprecedentedly large and multi-perspective set of information.

  4. Explaining Support Vector Machines: A Color Based Nomogram

    PubMed Central

    Van Belle, Vanya; Van Calster, Ben; Van Huffel, Sabine; Suykens, Johan A. K.; Lisboa, Paulo

    2016-01-01

    Problem setting Support vector machines (SVMs) are very popular tools for classification, regression and other problems. Due to the large choice of kernels they can be applied with, a large variety of data can be analysed using these tools. Machine learning thanks its popularity to the good performance of the resulting models. However, interpreting the models is far from obvious, especially when non-linear kernels are used. Hence, the methods are used as black boxes. As a consequence, the use of SVMs is less supported in areas where interpretability is important and where people are held responsible for the decisions made by models. Objective In this work, we investigate whether SVMs using linear, polynomial and RBF kernels can be explained such that interpretations for model-based decisions can be provided. We further indicate when SVMs can be explained and in which situations interpretation of SVMs is (hitherto) not possible. Here, explainability is defined as the ability to produce the final decision based on a sum of contributions which depend on one single or at most two input variables. Results Our experiments on simulated and real-life data show that explainability of an SVM depends on the chosen parameter values (degree of polynomial kernel, width of RBF kernel and regularization constant). When several combinations of parameter values yield the same cross-validation performance, combinations with a lower polynomial degree or a larger kernel width have a higher chance of being explainable. Conclusions This work summarizes SVM classifiers obtained with linear, polynomial and RBF kernels in a single plot. Linear and polynomial kernels up to the second degree are represented exactly. For other kernels an indication of the reliability of the approximation is presented. The complete methodology is available as an R package and two apps and a movie are provided to illustrate the possibilities offered by the method. PMID:27723811

  5. How Do Consumers Evaluate Explainer Videos? An Empirical Study on the Effectiveness and Efficiency of Different Explainer Video Formats

    ERIC Educational Resources Information Center

    Krämer, Andreas; Böhrs, Sandra

    2017-01-01

    There is a significant rise in the use of videos. More and more people use videos not only as a source of information but also as learning tool. This article explores the future potential of explainer videos, a format that conveys complex facts to a target group within a very short time. The findings are based on an empirical study representative…

  6. How Can Evolutionary Psychology Successfully Explain Personality and Individual Differences?

    PubMed

    Buss, David M

    2009-07-01

    Although evolutionary psychology has been successful in explaining some species-typical and sex-differentiated adaptations, a large question that has largely eluded the field is this: How can the field successfully explain personality and individual differences? This article highlights some promising theoretical directions for tackling this question. These include life-history theory, costly signaling theory, environmental variability in fitness optima, frequency-dependent selection, mutation load, and flexibly contingent shifts in strategy according to environmental conditions. Tackling the explanatory question also requires progress on three fronts: (a) reframing some personality traits as forms of strategic individual differences; (b) providing a nonarbitrary, evolutionary-based formulation of environments as distributions and salience profiles of adaptive problems; and (c) identifying which strategies thrive and which falter in these differing problem-defined environments.

  7. 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

  8. Explaining dehumanization among children: the interspecies model of prejudice.

    PubMed

    Costello, Kimberly; Hodson, Gordon

    2014-03-01

    Although many theoretical approaches have emerged to explain prejudices expressed by children, none incorporate outgroup dehumanization, a key predictor of prejudice among adults. According to the Interspecies Model of Prejudice, beliefs in the human-animal divide facilitate outgroup prejudice through fostering animalistic dehumanization (Costello & Hodson, 2010). In the present investigation, White children attributed Black children fewer 'uniquely human' characteristics, representing the first systematic evidence of racial dehumanization among children (Studies 1 and 2). In Study 2, path analyses supported the Interspecies Model of Prejudice: children's human-animal divide beliefs predicted greater racial prejudice, an effect explained by heightened racial dehumanization. Similar patterns emerged among parents. Furthermore, parent Social Dominance Orientation predicted child prejudice indirectly through children's endorsement of a hierarchical human-animal divide and subsequent dehumanizing tendencies. Encouragingly, children's human-animal divide perceptions were malleable to an experimental prime highlighting animal-human similarity. Implications for prejudice interventions are considered.

  9. Climate variation explains a third of global crop yield variability

    PubMed Central

    Ray, Deepak K.; Gerber, James S.; MacDonald, Graham K.; West, Paul C.

    2015-01-01

    Many studies have examined the role of mean climate change in agriculture, but an understanding of the influence of inter-annual climate variations on crop yields in different regions remains elusive. We use detailed crop statistics time series for ~13,500 political units to examine how recent climate variability led to variations in maize, rice, wheat and soybean crop yields worldwide. While some areas show no significant influence of climate variability, in substantial areas of the global breadbaskets, >60% of the yield variability can be explained by climate variability. Globally, climate variability accounts for roughly a third (~32–39%) of the observed yield variability. Our study uniquely illustrates spatial patterns in the relationship between climate variability and crop yield variability, highlighting where variations in temperature, precipitation or their interaction explain yield variability. We discuss key drivers for the observed variations to target further research and policy interventions geared towards buffering future crop production from climate variability. PMID:25609225

  10. Explaining large-scale patterns of vertebrate diversity

    PubMed Central

    Wiens, John J.

    2015-01-01

    The major clades of vertebrates differ dramatically in their current species richness, from 2 to more than 32 000 species each, but the causes of this variation remain poorly understood. For example, a previous study noted that vertebrate clades differ in their diversification rates, but did not explain why they differ. Using a time-calibrated phylogeny and phylogenetic comparative methods, I show that most variation in diversification rates among 12 major vertebrate clades has a simple ecological explanation: predominantly terrestrial clades (i.e. birds, mammals, and lizards and snakes) have higher net diversification rates than predominantly aquatic clades (i.e. amphibians, crocodilians, turtles and all fish clades). These differences in diversification rates are then strongly related to patterns of species richness. Habitat may be more important than other potential explanations for richness patterns in vertebrates (such as climate and metabolic rates) and may also help explain patterns of species richness in many other groups of organisms. PMID:26202428

  11. The meaning of a metapsychology as an instrument for "explaining".

    PubMed

    Imbasciati, Antonio

    2011-01-01

    The author points out how some psychoanalytical concepts that were considered as fundamental and unchangeable are actually changing. Child Psychoanalysis with its "infant psychoanalysis" (babies and parents) and other psychological sciences have contributed to this development. Nevertheless, many psychoanalysts have not taken this new knowledge into account. The author ascribes it to the lack of an epistemological distinction between "describing" (facts) and "explaining" (hypotheses), that is, between what are known as discoveries in psychoanalysis and what are theories instead. No theory can be a discovery but rather a hypothetical conceptual instrument trying to explain discoveries. Freud's Metapsychology is a hypothetical instrument which needs to be changed today, since the progress of psychoanalysis and other sciences allows for better instruments. The author wishes for studies which may outline other explicit metapsychologies that may better explicate what is being observed.

  12. Microbes can help explain the evolution of host altruism

    PubMed Central

    Lewin-Epstein, Ohad; Aharonov, Ranit; Hadany, Lilach

    2017-01-01

    The evolution of altruistic behaviour, which is costly to the donor but beneficial for the recipient, is among the most intriguing questions in evolutionary biology. Several theories have been proposed to explain it, including kin selection, group selection and reciprocity. Here we propose that microbes that manipulate their hosts to act altruistically could be favoured by selection, and may play a role in the widespread occurrence of altruism. Using computational models, we find that microbe-induced altruism can explain the evolution of host altruistic behaviour under wider conditions than host-centred theories, including in a fully mixed host population, without repeating interactions or individual recognition. Our results suggest that factors such as antibiotics that kill microbes might negatively affect cooperation in a wide range of organisms. PMID:28079112

  13. Climate variation explains a third of global crop yield variability

    NASA Astrophysics Data System (ADS)

    Ray, Deepak K.; Gerber, James S.; MacDonald, Graham K.; West, Paul C.

    2015-01-01

    Many studies have examined the role of mean climate change in agriculture, but an understanding of the influence of inter-annual climate variations on crop yields in different regions remains elusive. We use detailed crop statistics time series for ~13,500 political units to examine how recent climate variability led to variations in maize, rice, wheat and soybean crop yields worldwide. While some areas show no significant influence of climate variability, in substantial areas of the global breadbaskets, >60% of the yield variability can be explained by climate variability. Globally, climate variability accounts for roughly a third (~32-39%) of the observed yield variability. Our study uniquely illustrates spatial patterns in the relationship between climate variability and crop yield variability, highlighting where variations in temperature, precipitation or their interaction explain yield variability. We discuss key drivers for the observed variations to target further research and policy interventions geared towards buffering future crop production from climate variability.

  14. Climate variation explains a third of global crop yield variability.

    PubMed

    Ray, Deepak K; Gerber, James S; MacDonald, Graham K; West, Paul C

    2015-01-22

    Many studies have examined the role of mean climate change in agriculture, but an understanding of the influence of inter-annual climate variations on crop yields in different regions remains elusive. We use detailed crop statistics time series for ~13,500 political units to examine how recent climate variability led to variations in maize, rice, wheat and soybean crop yields worldwide. While some areas show no significant influence of climate variability, in substantial areas of the global breadbaskets, >60% of the yield variability can be explained by climate variability. Globally, climate variability accounts for roughly a third (~32-39%) of the observed yield variability. Our study uniquely illustrates spatial patterns in the relationship between climate variability and crop yield variability, highlighting where variations in temperature, precipitation or their interaction explain yield variability. We discuss key drivers for the observed variations to target further research and policy interventions geared towards buffering future crop production from climate variability.

  15. Tuned Normalization Explains the Size of Attention Modulations

    PubMed Central

    Ni, Amy M.; Ray, Supratim; Maunsell, John H. R.

    2012-01-01

    SUMMARY The effect of attention on firing rates varies considerably within a single cortical area. The firing rate of some neurons is greatly modulated by attention while others are hardly affected. The reason for this variability across neurons is unknown. We found that the variability in attention modulation across neurons in area MT of macaques can be well explained by variability in the strength of tuned normalization across neurons. The presence of tuned normalization also explains a striking asymmetry in attention effects within neurons: when two stimuli are in a neuron’s receptive field, directing attention to the preferred stimulus modulates firing rates more than directing attention to the non-preferred stimulus. These findings show that much of the neuron-to-neuron variability in modulation of responses by attention depends on variability in the way the neurons process multiple stimuli, rather than differences in the influence of top-down signals related to attention. PMID:22365552

  16. Imitation explains the propagation, not the stability of animal culture.

    PubMed

    Claidière, Nicolas; Sperber, Dan

    2010-02-22

    For acquired behaviour to count as cultural, two conditions must be met: it must propagate in a social group, and it must remain stable across generations in the process of propagation. It is commonly assumed that imitation is the mechanism that explains both the spread of animal culture and its stability. We review the literature on transmission chain studies in chimpanzees (Pan troglodytes) and other animals, and we use a formal model to argue that imitation, which may well play a major role in the propagation of animal culture, cannot be considered faithful enough to explain its stability. We consider the contribution that other psychological and ecological factors might make to the stability of animal culture observed in the wild.

  17. Can transition radiation explain the ANITA event 3985267?

    NASA Astrophysics Data System (ADS)

    Motloch, Pavel; Alvarez-Muñiz, Jaime; Privitera, Paolo; Zas, Enrique

    2017-02-01

    We investigate whether transition radiation from a particle shower crossing the interface between Earth and air and induced by an Earth-skimming neutrino can explain the upward event announced recently by the ANITA Collaboration. While the properties of the observed signal can in principle be explained with transition radiation, a conservative upper limit on the experiment's aperture for this kind of signal shows that the flux necessary for a successful explanation is in tension with the current best limits from the Pierre Auger Observatory, the IceCube neutrino detector, and the ANITA balloon. We also show that in this scenario, the direction of the incoming neutrino is determined precisely to within a few degrees, combining the polarization properties of the observed events with the Earth opacity to ultrahigh energy neutrinos.

  18. Imitation explains the propagation, not the stability of animal culture

    PubMed Central

    Claidière, Nicolas; Sperber, Dan

    2010-01-01

    For acquired behaviour to count as cultural, two conditions must be met: it must propagate in a social group, and it must remain stable across generations in the process of propagation. It is commonly assumed that imitation is the mechanism that explains both the spread of animal culture and its stability. We review the literature on transmission chain studies in chimpanzees (Pan troglodytes) and other animals, and we use a formal model to argue that imitation, which may well play a major role in the propagation of animal culture, cannot be considered faithful enough to explain its stability. We consider the contribution that other psychological and ecological factors might make to the stability of animal culture observed in the wild. PMID:19889707

  19. Mechanical vulnerability explains size-dependent mortality of reef corals

    PubMed Central

    Madin, Joshua S; Baird, Andrew H; Dornelas, Maria; Connolly, Sean R

    2014-01-01

    Understanding life history and demographic variation among species within communities is a central ecological goal. Mortality schedules are especially important in ecosystems where disturbance plays a major role in structuring communities, such as coral reefs. Here, we test whether a trait-based, mechanistic model of mechanical vulnerability in corals can explain mortality schedules. Specifically, we ask whether species that become increasingly vulnerable to hydrodynamic dislodgment as they grow have bathtub-shaped mortality curves, whereas species that remain mechanically stable have decreasing mortality rates with size, as predicted by classical life history theory for reef corals. We find that size-dependent mortality is highly consistent between species with the same growth form and that the shape of size-dependent mortality for each growth form can be explained by mechanical vulnerability. Our findings highlight the feasibility of predicting assemblage-scale mortality patterns on coral reefs with trait-based approaches. PMID:24894390

  20. Explaining ecological clusters of maternal depression in South Western Sydney.

    PubMed

    Eastwood ED, John; Kemp, Lynn; Jalaludin, Bin

    2014-01-24

    The aim of the qualitative study reported here was to: 1) explain the observed clustering of postnatal depressive symptoms in South Western Sydney; and 2) identify group-level mechanisms that would add to our understanding of the social determinants of maternal depression. Critical realism provided the methodological underpinning for the study. The setting was four local government areas in South Western Sydney, Australia. Child and Family practitioners and mothers in naturally occurring mothers groups were interviewed. Using an open coding approach to maximise emergence of patterns and relationships we have identified seven theoretical concepts that might explain the observed spatial clustering of maternal depression. The theoretical concepts identified were: Community-level social networks; Social Capital and Social Cohesion; "Depressed community"; Access to services at the group level; Ethnic segregation and diversity; Supportive social policy; and Big business. We postulate that these regional structural, economic, social and cultural mechanisms partially explain the pattern of maternal depression observed in families and communities within South Western Sydney. We further observe that powerful global economic and political forces are having an impact on the local situation. The challenge for policy and practice is to support mothers and their families within this adverse regional and global-economic context.

  1. Genetic pleiotropy explains associations between musical auditory discrimination and intelligence.

    PubMed

    Mosing, Miriam A; Pedersen, Nancy L; Madison, Guy; Ullén, Fredrik

    2014-01-01

    Musical aptitude is commonly measured using tasks that involve discrimination of different types of musical auditory stimuli. Performance on such different discrimination tasks correlates positively with each other and with intelligence. However, no study to date has explored these associations using a genetically informative sample to estimate underlying genetic and environmental influences. In the present study, a large sample of Swedish twins (N = 10,500) was used to investigate the genetic architecture of the associations between intelligence and performance on three musical auditory discrimination tasks (rhythm, melody and pitch). Phenotypic correlations between the tasks ranged between 0.23 and 0.42 (Pearson r values). Genetic modelling showed that the covariation between the variables could be explained by shared genetic influences. Neither shared, nor non-shared environment had a significant effect on the associations. Good fit was obtained with a two-factor model where one underlying shared genetic factor explained all the covariation between the musical discrimination tasks and IQ, and a second genetic factor explained variance exclusively shared among the discrimination tasks. The results suggest that positive correlations among musical aptitudes result from both genes with broad effects on cognition, and genes with potentially more specific influences on auditory functions.

  2. Conceptual Foundations of Systems Biology Explaining Complex Cardiac Diseases

    PubMed Central

    Louridas, George E.; Lourida, Katerina G.

    2017-01-01

    Systems biology is an important concept that connects molecular biology and genomics with computing science, mathematics and engineering. An endeavor is made in this paper to associate basic conceptual ideas of systems biology with clinical medicine. Complex cardiac diseases are clinical phenotypes generated by integration of genetic, molecular and environmental factors. Basic concepts of systems biology like network construction, modular thinking, biological constraints (downward biological direction) and emergence (upward biological direction) could be applied to clinical medicine. Especially, in the field of cardiology, these concepts can be used to explain complex clinical cardiac phenotypes like chronic heart failure and coronary artery disease. Cardiac diseases are biological complex entities which like other biological phenomena can be explained by a systems biology approach. The above powerful biological tools of systems biology can explain robustness growth and stability during disease process from modulation to phenotype. The purpose of the present review paper is to implement systems biology strategy and incorporate some conceptual issues raised by this approach into the clinical field of complex cardiac diseases. Cardiac disease process and progression can be addressed by the holistic realistic approach of systems biology in order to define in better terms earlier diagnosis and more effective therapy. PMID:28230815

  3. Predator mimicry, not conspicuousness, explains the efficacy of butterfly eyespots

    PubMed Central

    De Bona, Sebastiano; Valkonen, Janne K.; López-Sepulcre, Andrés; Mappes, Johanna

    2015-01-01

    Large conspicuous eyespots on butterfly wings have been shown to deter predators. This has been traditionally explained by mimicry of vertebrate eyes, but recently the classic eye-mimicry hypothesis has been challenged. It is proposed that the conspicuousness of the eyespot, not mimicry, is what causes aversion due to sensory biases, neophobia or sensory overloads. We conducted an experiment to directly test whether the eye-mimicry or the conspicuousness hypothesis better explain eyespot efficacy. We used great tits (Parus major) as model predator, and tested their reaction towards animated images on a computer display. Birds were tested against images of butterflies without eyespots, with natural-looking eyespots, and manipulated spots with the same contrast but reduced resemblance to an eye, as well as images of predators (owls) with and without eyes. We found that mimetic eyespots were as effective as true eyes of owls and more efficient in eliciting an aversive response than modified, less mimetic but equally contrasting eyespots. We conclude that the eye-mimicry hypothesis explains our results better than the conspicuousness hypothesis and is thus likely to be an important mechanism behind the evolution of butterfly eyespots. PMID:25854889

  4. Weather explains high annual variation in butterfly dispersal

    PubMed Central

    Rytteri, Susu; Heikkinen, Risto K.; Heliölä, Janne; von Bagh, Peter

    2016-01-01

    Weather conditions fundamentally affect the activity of short-lived insects. Annual variation in weather is therefore likely to be an important determinant of their between-year variation in dispersal, but conclusive empirical studies are lacking. We studied whether the annual variation of dispersal can be explained by the flight season's weather conditions in a Clouded Apollo (Parnassius mnemosyne) metapopulation. This metapopulation was monitored using the mark–release–recapture method for 12 years. Dispersal was quantified for each monitoring year using three complementary measures: emigration rate (fraction of individuals moving between habitat patches), average residence time in the natal patch, and average distance moved. There was much variation both in dispersal and average weather conditions among the years. Weather variables significantly affected the three measures of dispersal and together with adjusting variables explained 79–91% of the variation observed in dispersal. Different weather variables became selected in the models explaining variation in three dispersal measures apparently because of the notable intercorrelations. In general, dispersal rate increased with increasing temperature, solar radiation, proportion of especially warm days, and butterfly density, and decreased with increasing cloudiness, rainfall, and wind speed. These results help to understand and model annually varying dispersal dynamics of species affected by global warming. PMID:27440662

  5. Face context advantage explained by vernier and separation discrimination acuity.

    PubMed

    Vesker, Michael; Wilson, Hugh R

    2012-01-01

    Seeing facial features in the context of a full face is known to provide an advantage for perception. Using an interocular separation perception task we confirmed that seeing eyes within the context of a face improves discrimination in synthetic faces. We also show that this improvement of the face context can be explained using the presence of individual components of the face such as the nose mouth, or head-outline. We demonstrate that improvements due to the presence of the nose, and head-outline can be explained in terms of two-point separation measurements, obeying Weber's law as established in the literature. We also demonstrate that performance improvements due to the presence of the mouth can be explained in terms of Vernier acuity judgments between eye positions and the corners of the mouth. Overall, our study shows that the improvements in perception of facial features due to the face context effect can be traced to well understood basic visual measurements that may play a very general role in perceptual measurements of distance. Deficiencies in these measurements may also play a role in prosopagnosia. Additionally, we show interference of the eyebrows with the face-inversion effect for interocular discrimination.

  6. Explaining ecological clusters of maternal depression in South Western Sydney

    PubMed Central

    2014-01-01

    Background The aim of the qualitative study reported here was to: 1) explain the observed clustering of postnatal depressive symptoms in South Western Sydney; and 2) identify group-level mechanisms that would add to our understanding of the social determinants of maternal depression. Methods Critical realism provided the methodological underpinning for the study. The setting was four local government areas in South Western Sydney, Australia. Child and Family practitioners and mothers in naturally occurring mothers groups were interviewed. Results Using an open coding approach to maximise emergence of patterns and relationships we have identified seven theoretical concepts that might explain the observed spatial clustering of maternal depression. The theoretical concepts identified were: Community-level social networks; Social Capital and Social Cohesion; "Depressed community"; Access to services at the group level; Ethnic segregation and diversity; Supportive social policy; and Big business. Conclusions We postulate that these regional structural, economic, social and cultural mechanisms partially explain the pattern of maternal depression observed in families and communities within South Western Sydney. We further observe that powerful global economic and political forces are having an impact on the local situation. The challenge for policy and practice is to support mothers and their families within this adverse regional and global-economic context. PMID:24460690

  7. Does sexual selection explain human sex differences in aggression?

    PubMed

    Archer, John

    2009-08-01

    I argue that the magnitude and nature of sex differences in aggression, their development, causation, and variability, can be better explained by sexual selection than by the alternative biosocial version of social role theory. Thus, sex differences in physical aggression increase with the degree of risk, occur early in life, peak in young adulthood, and are likely to be mediated by greater male impulsiveness, and greater female fear of physical danger. Male variability in physical aggression is consistent with an alternative life history perspective, and context-dependent variability with responses to reproductive competition, although some variability follows the internal and external influences of social roles. Other sex differences, in variance in reproductive output, threat displays, size and strength, maturation rates, and mortality and conception rates, all indicate that male aggression is part of a sexually selected adaptive complex. Physical aggression between partners can be explained using different evolutionary principles, arising from the conflicts of interest between males and females entering a reproductive alliance, combined with variability following differences in societal gender roles. In this case, social roles are particularly important since they enable both the relatively equality in physical aggression between partners from Western nations, and the considerable cross-national variability, to be explained.

  8. What Explains Patterns of Diversification and Richness among Animal Phyla?

    PubMed

    Jezkova, Tereza; Wiens, John J

    2017-03-01

    Animal phyla vary dramatically in species richness (from one species to >1.2 million), but the causes of this variation remain largely unknown. Animals have also evolved striking variation in morphology and ecology, including sessile marine taxa lacking heads, eyes, limbs, and complex organs (e.g., sponges), parasitic worms (e.g., nematodes, platyhelminths), and taxa with eyes, skeletons, limbs, and complex organs that dominate terrestrial ecosystems (arthropods, chordates). Relating this remarkable variation in traits to the diversification and richness of animal phyla is a fundamental yet unresolved problem in biology. Here, we test the impacts of 18 traits (including morphology, ecology, reproduction, and development) on diversification and richness of extant animal phyla. Using phylogenetic multiple regression, the best-fitting model includes five traits that explain ∼74% of the variation in diversification rates (dioecy, parasitism, eyes/photoreceptors, a skeleton, nonmarine habitat). However, a model including just three (skeleton, parasitism, habitat) explains nearly as much variation (∼67%). Diversification rates then largely explain richness patterns. Our results also identify many striking traits that have surprisingly little impact on diversification (e.g., head, limbs, and complex circulatory and digestive systems). Overall, our results reveal the key factors that shape large-scale patterns of diversification and richness across >80% of all extant, described species.

  9. Predator mimicry, not conspicuousness, explains the efficacy of butterfly eyespots.

    PubMed

    De Bona, Sebastiano; Valkonen, Janne K; López-Sepulcre, Andrés; Mappes, Johanna

    2015-05-07

    Large conspicuous eyespots on butterfly wings have been shown to deter predators. This has been traditionally explained by mimicry of vertebrate eyes, but recently the classic eye-mimicry hypothesis has been challenged. It is proposed that the conspicuousness of the eyespot, not mimicry, is what causes aversion due to sensory biases, neophobia or sensory overloads. We conducted an experiment to directly test whether the eye-mimicry or the conspicuousness hypothesis better explain eyespot efficacy. We used great tits (Parus major) as model predator, and tested their reaction towards animated images on a computer display. Birds were tested against images of butterflies without eyespots, with natural-looking eyespots, and manipulated spots with the same contrast but reduced resemblance to an eye, as well as images of predators (owls) with and without eyes. We found that mimetic eyespots were as effective as true eyes of owls and more efficient in eliciting an aversive response than modified, less mimetic but equally contrasting eyespots. We conclude that the eye-mimicry hypothesis explains our results better than the conspicuousness hypothesis and is thus likely to be an important mechanism behind the evolution of butterfly eyespots. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  10. Explaining Racial Disparities in Infant Health in Brazil

    PubMed Central

    Nyarko, Kwame A.; Lopez-Camelo, Jorge; Castilla, Eduardo E.

    2013-01-01

    Objectives. We sought to quantify how socioeconomic, health care, demographic, and geographic effects explain racial disparities in low birth weight (LBW) and preterm birth (PTB) rates in Brazil. Methods. We employed a sample of 8949 infants born between 1995 and 2009 in 15 cities and 7 provinces in Brazil. We focused on disparities in LBW (< 2500 g) and PTB (< 37 gestational weeks) prevalence between infants of African ancestry alone or African mixed with other ancestries, and European ancestry alone. We used a decomposition model to quantify the contributions of conceptually relevant factors to these disparities. Results. The model explained 45% to 94% of LBW and 64% to 94% of PTB disparities between the African ancestry groups and European ancestry. Differences in prenatal care use and geographic location were the most important contributors, followed by socioeconomic differences. The model explained the majority of the disparities for mixed African ancestry and part of the disparity for African ancestry alone. Conclusions. Public policies to improve children’s health should target prenatal care and geographic location differences to reduce health disparities between infants of African and European ancestries in Brazil. PMID:23409894

  11. Explaining racial disparities in infant health in Brazil.

    PubMed

    Nyarko, Kwame A; Lopez-Camelo, Jorge; Castilla, Eduardo E; Wehby, George L

    2015-10-01

    We sought to quantify how socioeconomic, health care, demographic, and geographic effects explain racial disparities in low birth weight (LBW) and preterm birth (PTB) rates in Brazil. We employed a sample of 8949 infants born between 1995 and 2009 in 15 cities and 7 provinces in Brazil. We focused on disparities in LBW (< 2500 g) and PTB (< 37 gestational weeks) prevalence between infants of African ancestry alone or African mixed with other ancestries, and European ancestry alone. We used a decomposition model to quantify the contributions of conceptually relevant factors to these disparities. The model explained 45% to 94% of LBW and 64% to 94% of PTB disparities between the African ancestry groups and European ancestry. Differences in prenatal care use and geographic location were the most important contributors, followed by socioeconomic differences. The model explained the majority of the disparities for mixed African ancestry and part of the disparity for African ancestry alone. Public policies to improve children's health should target prenatal care and geographic location differences to reduce health disparities between infants of African and European ancestries in Brazil.

  12. [Explaining racial disparities in infant health in Brazil].

    PubMed

    A Nyarko, Kwame; López-Camelo, Jorge; E Castilla, Eduardo; L Wehby, George

    2014-04-01

    We sought to quantify how socioeconomic, health care, demographic, and geographic effects explain racial disparities in low birth weight (LBW) and preterm birth (PTB) rates in Brazil. We employed a sample of 8 949 infants born between 1995 and 2009 in 15 cities and 7 provinces in Brazil. We focused on disparities in LBW (< 2 500 g) and PTB (< 37 gestational weeks) prevalence between infants of African ancestry alone or African mixed with other ancestries, and European ancestry alone. We used a decomposition model to quantify the contributions of conceptually relevant factors to these disparities. The model explained 45% to 94% of LBW and 64% to 94% of PTB disparities between the African ancestry groups and European ancestry. Differences in prenatal care use and geographic location were the most important contributors, followed by socioeconomic differences. The model explained the majority of the disparities for mixed African ancestry and part of the disparity for African ancestry alone. Public policies to improve children's health should target prenatal care and geographic location differences to reduce health disparities between infants of African and European ancestries in Brazil.

  13. Weather explains high annual variation in butterfly dispersal.

    PubMed

    Kuussaari, Mikko; Rytteri, Susu; Heikkinen, Risto K; Heliölä, Janne; von Bagh, Peter

    2016-07-27

    Weather conditions fundamentally affect the activity of short-lived insects. Annual variation in weather is therefore likely to be an important determinant of their between-year variation in dispersal, but conclusive empirical studies are lacking. We studied whether the annual variation of dispersal can be explained by the flight season's weather conditions in a Clouded Apollo (Parnassius mnemosyne) metapopulation. This metapopulation was monitored using the mark-release-recapture method for 12 years. Dispersal was quantified for each monitoring year using three complementary measures: emigration rate (fraction of individuals moving between habitat patches), average residence time in the natal patch, and average distance moved. There was much variation both in dispersal and average weather conditions among the years. Weather variables significantly affected the three measures of dispersal and together with adjusting variables explained 79-91% of the variation observed in dispersal. Different weather variables became selected in the models explaining variation in three dispersal measures apparently because of the notable intercorrelations. In general, dispersal rate increased with increasing temperature, solar radiation, proportion of especially warm days, and butterfly density, and decreased with increasing cloudiness, rainfall, and wind speed. These results help to understand and model annually varying dispersal dynamics of species affected by global warming.

  14. Strong resonance explains cycles in sockeye salmon populations

    NASA Astrophysics Data System (ADS)

    Guill, Christian; Drossel, Barbara

    2010-03-01

    The number of spawning sockeye salmon that return to their native streams in the Fraser river basin exhibit striking four-year oscillations, the dimension of which being no less notable than the widely known cycles of lynx and snowshoe hare in Canada. The period of the oscillation corresponds to the dominant generation time of these fish, and the phase differs between different stocks. Various not fully convincing explanations have been attempted, ascribing this phenomenon to transient effects, to stochastic influences, to depensatory predation, or to genetic effects. We show that these oscillations can be explained as a stable dynamical attractor of the population dynamics, resulting from a strong resonance near a Neimark Sacker bifurcation. This explains not only the long-term persistence of these oscillations, but also reproduces correctly the sequence of two strong years followed by two weak years. Furthermore, it explains the observations that the oscillations occur only in oligotrophic lakes, and that they do not occur in salmon species that have a longer generation time.

  15. What explains childhood violence? Micro correlates from VACS surveys.

    PubMed

    Ravi, Shamika; Ahluwalia, Rahul

    2017-03-01

    Violence in childhood is a serious health, social and human rights concern globally, there is, however, little understanding about the factors that explain the various forms of violence in childhood. This paper uses data on childhood violence for 10,042 individuals from four countries. We report Odds Ratios from pooled logit regression analysis with country fixed effects model. There is no gender difference in the overall incidence of childhood violence. The data shows that 78% of girls and 79% of boys have suffered some form of violence before the age of 18 years. Odds of violence are higher among richer households, among individuals who have attended school and among individuals who have been married or in marriage-like arrangements. Individuals who justify wife beating have significantly higher likelihood of having faced violence themselves. Most perpetrators of violence against children - physical, emotional and sexual - are people known to them in their homes and community, and not strangers. There is limited understanding of the factors that explain violence in childhood. This study highlights some key factors that can explain this phenomenon.

  16. Explaining formation of Astronomical Jets using Dynamic Universe Model

    NASA Astrophysics Data System (ADS)

    Naga Parameswara Gupta, Satyavarapu

    2016-07-01

    Astronomical jets are observed from the centres of many Galaxies including our own Milkyway. The formation of such jet is explained using SITA simulations of Dynamic Universe Model. For this purpose the path traced by a test neutron is calculated and depicted using a set up of one densemass of the mass equivalent to mass of Galaxy center, 90 stars with similar masses of stars near Galaxy center, mass equivalents of 23 Globular Cluster groups, 16 Milkyway parts, Andromeda and Triangulum Galaxies at appropriate distances. Five different kinds of theoretical simulations gave positive results The path travelled by this test neutron was found to be an astronomical jet emerging from Galaxy center. This is another result from Dynamic Universe Model. It solves new problems like a. Variable Mass Rocket Trajectory Problem b. Explaining Very long baseline interferometry (VLBI) observations c. Astronomical jets observed from Milkyway Center d. Prediction of Blue shifted Galaxies e. Explaining Pioneer Anomaly f. Prediction of New Horizons satellite trajectory etc. Dynamic Universe Model never reduces to General relativity on any condition. It uses a different type of mathematics based on Newtonian physics. This mathematics used here is simple and straightforward. As there are no differential equations present in Dynamic Universe Model, the set of equations give single solution in x y z Cartesian coordinates for every point mass for every time step

  17. Earthquake lubrication and healing explained by amorphous nanosilica

    NASA Astrophysics Data System (ADS)

    Rowe, C. D.; Lamothe, K. G.; Rempe, M.; Andrews, M.; Mitchell, T. M.; Di Toro, G.; White, J. C.

    2015-12-01

    Earthquake slip and rupture propagation require fault strength to decrease during slip. Extreme shear weakening observed in laboratory friction experiments on silica-rich rocks has been explained by the formation of a hydrated amorphous 'silica gel' on the slip surface, but the mode of formation and deformation behavior of this material are not known. In addition, the wear material displays time-dependent strengthening on timescales of hours to days. We performed shearing experiments on chert rocks and analyzed the wear material formed at a range of slip rates from 10-4 - 10-1 m/s. We show by transmission electron microscopy (TEM) and X-ray diffraction that silica lubrication is the result of the formation of amorphous nanopowder rather than a gel. The nanopowder has distinct structure and properties when compared to commercially available amorphous silica nanoparticles, which result from the degree and distribution of hydration and the style of bond strain within particles (observed by Raman spectroscopy and FTIR). The lubrication effect is due to intra-particle plasticity, even at low temperature and interparticle lubrication caused by trapping of water layers between hydrated surfaces. The hours to days timescale of healing may be explained by the natural time-dependent sintering between the hydrated surfaces of the nanopowder. Formation of amorphous silica nanopowders during slip can explain the general characteristics of earthquake ruptures, including the timescales of coseismic weakening and post-seismic healing.

  18. Conceptual Foundations of Systems Biology Explaining Complex Cardiac Diseases.

    PubMed

    Louridas, George E; Lourida, Katerina G

    2017-02-21

    Systems biology is an important concept that connects molecular biology and genomics with computing science, mathematics and engineering. An endeavor is made in this paper to associate basic conceptual ideas of systems biology with clinical medicine. Complex cardiac diseases are clinical phenotypes generated by integration of genetic, molecular and environmental factors. Basic concepts of systems biology like network construction, modular thinking, biological constraints (downward biological direction) and emergence (upward biological direction) could be applied to clinical medicine. Especially, in the field of cardiology, these concepts can be used to explain complex clinical cardiac phenotypes like chronic heart failure and coronary artery disease. Cardiac diseases are biological complex entities which like other biological phenomena can be explained by a systems biology approach. The above powerful biological tools of systems biology can explain robustness growth and stability during disease process from modulation to phenotype. The purpose of the present review paper is to implement systems biology strategy and incorporate some conceptual issues raised by this approach into the clinical field of complex cardiac diseases. Cardiac disease process and progression can be addressed by the holistic realistic approach of systems biology in order to define in better terms earlier diagnosis and more effective therapy.

  19. Explaining Racial Disparities in Infant Health in Brazil

    PubMed Central

    Nyarko, Kwame A.; Lopez-Camelo, Jorge; Castilla, Eduardo E.

    2015-01-01

    Objectives. We sought to quantify how socioeconomic, health care, demographic, and geographic effects explain racial disparities in low birth weight (LBW) and preterm birth (PTB) rates in Brazil. Methods. We employed a sample of 8949 infants born between 1995 and 2009 in 15 cities and 7 provinces in Brazil. We focused on disparities in LBW (< 2500 g) and PTB (< 37 gestational weeks) prevalence between infants of African ancestry alone or African mixed with other ancestries, and European ancestry alone. We used a decomposition model to quantify the contributions of conceptually relevant factors to these disparities. Results. The model explained 45% to 94% of LBW and 64% to 94% of PTB disparities between the African ancestry groups and European ancestry. Differences in prenatal care use and geographic location were the most important contributors, followed by socioeconomic differences. The model explained the majority of the disparities for mixed African ancestry and part of the disparity for African ancestry alone. Conclusions. Public policies to improve children’s health should target prenatal care and geographic location differences to reduce health disparities between infants of African and European ancestries in Brazil. PMID:26313046

  20. Explaining the Early Development and Health of Teen Mothers’ Children*

    PubMed Central

    Mollborn, Stefanie; Dennis, Jeff A.

    2013-01-01

    The transmission of social disadvantage from teenage mothers to their children is well established, but when and why do these disparities emerge in the early life course? Using nationally representative data from the Early Childhood Longitudinal Study-Birth Cohort, this study investigated the relationship between teen childbearing and children’s cognition, behavior, and health from infancy through preschool. Developmental disparities between teenage mothers’ children and others were largely nonexistent at 9 months but accumulated with age. Having a teenage mother predicted compromised development across several domains by age 4½. Our conceptual model expected preexisting disadvantage, ongoing resource disadvantage, and compromised parenting quality to explain the association between teen childbearing and child outcomes. Preexisting social disadvantage accounted for much of this relationship. Financial, social, and material resources in the child’s household partially or fully explained each of the remaining significant relationships between teenage childbearing and child outcomes. Parenting quality explained a smaller proportion of these relationships than did resources, and these factors’ influences were largely independent. Because children of teenage mothers with a modest set of resources were not predicted to have compromised development, resources provided in early childhood may have the potential to reduce developmental disparities for teenage mothers’ children. PMID:23630407

  1. Explaining socioeconomic inequalities in exclusive breast feeding in Norway.

    PubMed

    Bærug, Anne; Laake, Petter; Løland, Beate Fossum; Tylleskär, Thorkild; Tufte, Elisabeth; Fretheim, Atle

    2017-08-01

    In high-income countries, lower socioeconomic position is associated with lower rates of breast feeding, but it is unclear what factors explain this inequality. Our objective was to examine the association between socioeconomic position and exclusive breast feeding, and to explore whether socioeconomic inequality in exclusive breast feeding could be explained by other sociodemographic characteristics, for example, maternal age and parity, smoking habits, birth characteristics, quality of counselling and breastfeeding difficulties. We used data from a questionnaire sent to mothers when their infants were five completed months as part of a trial of a breastfeeding intervention in Norway. We used maternal education as an indicator of socioeconomic position. Analyses of 1598 mother-infant pairs were conducted using logistic regression to assess explanatory factors of educational inequalities in breast feeding. Socioeconomic inequalities in exclusive breast feeding were present from the beginning and persisted for five completed months, when 22% of the most educated mothers exclusively breast fed compared with 7% of the least educated mothers: OR 3.39 (95% CI 1.74 to 6.61). After adjustment for all potentially explanatory factors, the OR was reduced to 1.49 (95% CI 0.70 to 3.14). This decrease in educational inequality seemed to be mainly driven by sociodemographic factors, smoking habits and breastfeeding difficulties, in particular perceived milk insufficiency. Socioeconomic inequalities in exclusive breast feeding at 5 months were largely explained by sociodemographic factors, but also by modifiable factors, such as smoking habits and breastfeeding difficulties, which can be amenable to public health interventions. NCT01025362. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  2. Does cultural integration explain a mental health advantage for adolescents?

    PubMed

    Bhui, Kamaldeep S; Lenguerrand, Erik; Maynard, Maria J; Stansfeld, Stephen A; Harding, Seeromanie

    2012-06-01

    A mental health advantage has been observed among adolescents in urban areas. This prospective study tests whether cultural integration measured by cross-cultural friendships explains a mental health advantage for adolescents. A prospective cohort of adolescents was recruited from 51 secondary schools in 10 London boroughs. Cultural identity was assessed by friendship choices within and across ethnic groups. Cultural integration is one of four categories of cultural identity. Using gender-specific linear-mixed models we tested whether cultural integration explained a mental health advantage, and whether gender and age were influential. Demographic and other relevant factors, such as ethnic group, socio-economic status, family structure, parenting styles and perceived racism were also measured and entered into the models. Mental health was measured by the Strengths and Difficulties Questionnaire as a 'total difficulties score' and by classification as a 'probable clinical case'. A total of 6643 pupils in first and second years of secondary school (ages 11-13 years) took part in the baseline survey (2003/04) and 4785 took part in the follow-up survey in 2005-06. Overall mental health improved with age, more so in male rather than female students. Cultural integration (friendships with own and other ethnic groups) was associated with the lowest levels of mental health problems especially among male students. This effect was sustained irrespective of age, ethnicity and other potential explanatory variables. There was a mental health advantage among specific ethnic groups: Black Caribbean and Black African male students (Nigerian/Ghanaian origin) and female Indian students. This was not fully explained by cultural integration, although cultural integration was independently associated with better mental health. Cultural integration was associated with better mental health, independent of the mental health advantage found among specific ethnic groups: Black Caribbean and

  3. Traits underpinning desiccation resistance explain distribution patterns of terrestrial isopods.

    PubMed

    Dias, André T C; Krab, Eveline J; Mariën, Janine; Zimmer, Martin; Cornelissen, Johannes H C; Ellers, Jacintha; Wardle, David A; Berg, Matty P

    2013-07-01

    Predicted changes in soil water availability regimes with climate and land-use change will impact the community of functionally important soil organisms, such as macro-detritivores. Identifying and quantifying the functional traits that underlie interspecific differences in desiccation resistance will enhance our ability to predict both macro-detritivore community responses to changing water regimes and the consequences of the associated species shifts for organic matter turnover. Using path analysis, we tested (1) how interspecific differences in desiccation resistance among 22 northwestern European terrestrial isopod species could be explained by three underlying traits measured under standard laboratory conditions, namely, body ventral surface area, water loss rate and fatal water loss; (2) whether these relationships were robust to contrasting experimental conditions and to the phylogenetic relatedness effects being excluded; (3) whether desiccation resistance and hypothesized underlying traits could explain species distribution patterns in relation to site water availability. Water loss rate and (secondarily) fatal water loss together explained 90% of the interspecific variation in desiccation resistance. Our path model indicated that body surface area affects desiccation resistance only indirectly via changes in water loss rate. Our results also show that soil moisture determines isopod species distributions by filtering them according to traits underpinning desiccation resistance. These findings reveal that it is possible to use functional traits measured under standard conditions to predict soil biota responses to water availability in the field over broad spatial scales. Taken together, our results demonstrate an increasing need to generate mechanistic models to predict the effect of global changes on functionally important organisms.

  4. Synchronous population dynamics in California butterflies explained by climatic forcing.

    PubMed

    Pardikes, Nicholas A; Harrison, Joshua G; Shapiro, Arthur M; Forister, Matthew L

    2017-07-01

    A long-standing challenge for population biology has been to understand why some species are characterized by populations that fluctuate in size independently, while populations of other species fluctuate synchronously across space. The effects of climatic variation and dispersal have been invoked to explain synchronous population dynamics, however an understanding of the relative influence of these drivers in natural populations is lacking. Here we compare support for dispersal- versus climate-driven models of interspecific variation in synchrony using 27 years of observations of 65 butterfly species at 10 sites spanning 2750 m of elevation in Northern California. The degree of spatial synchrony exhibited by each butterfly species was used as a response in a unique approach that allowed us to investigate whether interspecific variation in response to climate or dispersal propensity was most predictive of interspecific variation in synchrony. We report that variation in sensitivity to climate explained 50% of interspecific variation in synchrony, whereas variation in dispersal propensity explained 23%. Sensitivity to the El Niño Southern Oscillation, a primary driver of regional climate, was the best predictor of synchrony. Combining sensitivity to climate and dispersal propensity into a single model did not greatly increase model performance, confirming the primacy of climatic sensitivity for driving spatial synchrony in butterflies. Finally, we uncovered a relationship between spatial synchrony and population decline that is consistent with theory, but small in magnitude, which suggests that the degree to which populations fluctuate in synchrony is of limited use for understanding the ongoing decline of the Northern California butterfly fauna.

  5. Individual Movement Variability Magnitudes Are Explained by Cortical Neural Variability.

    PubMed

    Haar, Shlomi; Donchin, Opher; Dinstein, Ilan

    2017-09-13

    Humans exhibit considerable motor variability even across trivial reaching movements. This variability can be separated into specific kinematic components such as extent and direction that are thought to be governed by distinct neural processes. Here, we report that individual subjects (males and females) exhibit different magnitudes of kinematic variability, which are consistent (within individual) across movements to different targets and regardless of which arm (right or left) was used to perform the movements. Simultaneous fMRI recordings revealed that the same subjects also exhibited different magnitudes of fMRI variability across movements in a variety of motor system areas. These fMRI variability magnitudes were also consistent across movements to different targets when performed with either arm. Cortical fMRI variability in the posterior-parietal cortex of individual subjects explained their movement-extent variability. This relationship was apparent only in posterior-parietal cortex and not in other motor system areas, thereby suggesting that individuals with more variable movement preparation exhibit larger kinematic variability. We therefore propose that neural and kinematic variability are reliable and interrelated individual characteristics that may predispose individual subjects to exhibit distinct motor capabilities.SIGNIFICANCE STATEMENT Neural activity and movement kinematics are remarkably variable. Although intertrial variability is rarely studied, here, we demonstrate that individual human subjects exhibit distinct magnitudes of neural and kinematic variability that are reproducible across movements to different targets and when performing these movements with either arm. Furthermore, when examining the relationship between cortical variability and movement variability, we find that cortical fMRI variability in parietal cortex of individual subjects explained their movement extent variability. This enabled us to explain why some subjects

  6. Explaining human uniqueness: genome interactions with environment, behaviour and culture

    PubMed Central

    Varki, Ajit; Geschwind, Daniel H.; Eichler, Evan E.

    2009-01-01

    What makes us human? Specialists in each discipline respond through the lens of their own expertise. In fact, ‘anthropogeny’ (explaining the origin of humans) requires a transdisciplinary approach that eschews such barriers. Here we take a genomic and genetic perspective towards molecular variation, explore systems analysis of gene expression and discuss an organ-systems approach. Rejecting any ‘genes versus environment’ dichotomy, we then consider genome interactions with environment, behaviour and culture, finally speculating that aspects of human uniqueness arose because of a primate evolutionary trend towards increasing and irreversible dependence on learned behaviours and culture — perhaps relaxing allowable thresholds for large-scale genomic diversity. PMID:18802414

  7. Explaining human uniqueness: genome interactions with environment, behaviour and culture.

    PubMed

    Varki, Ajit; Geschwind, Daniel H; Eichler, Evan E

    2008-10-01

    What makes us human? Specialists in each discipline respond through the lens of their own expertise. In fact, 'anthropogeny' (explaining the origin of humans) requires a transdisciplinary approach that eschews such barriers. Here we take a genomic and genetic perspective towards molecular variation, explore systems analysis of gene expression and discuss an organ-systems approach. Rejecting any 'genes versus environment' dichotomy, we then consider genome interactions with environment, behaviour and culture, finally speculating that aspects of human uniqueness arose because of a primate evolutionary trend towards increasing and irreversible dependence on learned behaviours and culture - perhaps relaxing allowable thresholds for large-scale genomic diversity.

  8. Recent advances in explaining fertility declines in the third world.

    PubMed

    Sharma, R K

    1984-01-01

    The purpose of this discussion is to provide a theoretical-methodological review of some recent socioeconomic theories that have been advanced to explain fertility decline in the 3rd world. Each theory is analyzed in terms of its theoretical claims and the methodology used in testing it. The intent is not so much with whether a particular theory has succeeded in explaining fertility decline but rather with the theoretical-methodological problems inherent in any attempt to explain fertility decline. The theories chosen are those theories that are explicity sociological in orientation or those that contain a significant sociological component. These theories are classified into 4 groups: proximate determinants of fertility; the "Synthesis Framework" of Easterlin; styles of development and fertility decline; and the "Wealth Flow" theory of fertility decline. Bongaarts (1978) developed an analytically simple yet comprehensive quantitative model of the relationship between the so-called intermediate variables and fertility. It can be either biological (such as sterility) or behavioral (such as contraceptive use)in nature. The most important finding from the application of Bongaart¿s framework (1982) is that fertility differences among populations are primarily due to variations in only 4 intermediate variables, namely proportion married, contraception, induced abortion, and postpartum infecundability. A knowledge of which proximate variable is responsible for fertility decline can narrow the search for social causes. The task of social research isultimately to understand such social causes that work through proximate variables to determine fertility. The "Synthesis Framework" of Easterlin attempts to accomplish precisely this by incorporating proximate variables within a broader socioeconomic framework. Those attempting to study the relationship between styles of development and fertility decline share this objective. The task of fertility research needs to be expanded

  9. Explaining resource consumption among non-normal neonates

    PubMed Central

    Schwartz, Rachel M.; Michelman, Thomas; Pezzullo, John; Phibbs, Ciaran S.

    1991-01-01

    The adoption by Medicare in 1983 of prospective payment using diagnosis-related groups (DRGs) has stimulated research to develop case-mix grouping schemes that more accurately predict resource consumption by patients. In this article, the authors explore a new method designed to improve case-mix classification for newborns through the use of birth weight in combination with DRGs to adjust the unexplained case-mix severity. Although the findings are developmental in nature, they reveal that the model significantly improves our ability to explain resource use. PMID:10122360

  10. Explaining resource consumption among non-normal neonates.

    PubMed

    Schwartz, R M; Michelman, T; Pezzullo, J; Phibbs, C S

    1991-01-01

    The adoption by Medicare in 1983 of prospective payment using diagnosis-related groups (DRGs) has stimulated research to develop case-mix grouping schemes that more accurately predict resource consumption by patients. In this article, the authors explore a new method designed to improve case-mix classification for newborns through the use of birth weight in combination with DRGs to adjust the unexplained case-mix severity. Although the findings are developmental in nature, they reveal that the model significantly improves our ability to explain resource use.

  11. Explaining Low Rates of Autism Among Hispanic Schoolchildren in Texas

    PubMed Central

    Walker, Tatjana; Mandell, David; Bayles, Bryan; Miller, Claudia S.

    2010-01-01

    In data from the Texas Educational Agency and the Health Resources and Services Administration, we found fewer autism diagnoses in school districts with higher percentages of Hispanic children. Our results are consistent with previous reports of autism rates 2 to 3 times as high among non-Hispanic Whites as among Hispanics. Socioeconomic factors failed to explain lower autism prevalence among Hispanic schoolchildren in Texas. These findings raise questions: Is autism underdiagnosed among Hispanics? Are there protective factors associated with Hispanic ethnicity? PMID:20019320

  12. Johnson or Goldwater-- Two Scientists Explain Their Choice.

    PubMed

    1964-10-16

    Since scientists seem to be showing an unusually active interest in the current presidential election campaign, Science has asked two politically active leaders of the scientific community to state the reasons for their political choice. Specifically, they were asked to explain their political preference, "with particular emphasis on matters of direct professional interest to the scientific community, such as federal support for education and basic research . . . (and) . . . how the outcome of the election might affect the present relationship between science and government, including the effects it might have on the development and quality of American science."

  13. The Poggendorff illusion explained by natural scene geometry.

    PubMed

    Howe, Catherine Q; Yang, Zhiyong; Purves, Dale

    2005-05-24

    One of the most intriguing of the many discrepancies between perceived spatial relationships and the physical structure of visual stimuli is the Poggendorff illusion, when an obliquely oriented line that is interrupted no longer appears collinear. Although many different theories have been proposed to explain this effect, there has been no consensus about its cause. Here, we use a database of range images (i.e., images that include the distance from the image plane of every pixel in the scene) to show that the probability distribution of the possible locations of line segments across an interval in natural environments can fully account for all of the behavior of this otherwise puzzling phenomenon.

  14. Can dark matter in galaxies be explained by relativistic corrections?

    NASA Astrophysics Data System (ADS)

    Korzynski, Mikolaj

    2007-06-01

    Cooperstock and Tieu proposed a model of galaxy, based on ordinary GR, in which no exotic dark matter is needed to explain the flat rotation curves in galaxies. I will present the arguments against this model. In particular, I will show that in their model the gravitational field is generated not only by the ordinary matter distribution, but by a infinitely thin, massive and rotating disc as well. This is a serious and incurable flaw and makes the Cooperstock Tieu metric unphysical as a galaxy model.

  15. Explaining and overcoming barriers to climate change adaptation

    NASA Astrophysics Data System (ADS)

    Eisenack, Klaus; Moser, Susanne C.; Hoffmann, Esther; Klein, Richard J. T.; Oberlack, Christoph; Pechan, Anna; Rotter, Maja; Termeer, Catrien J. A. M.

    2014-10-01

    The concept of barriers is increasingly used to describe the obstacles that hinder the planning and implementation of climate change adaptation. The growing literature on barriers to adaptation reveals not only commonly reported barriers, but also conflicting evidence, and few explanations of why barriers exist and change. There is thus a need for research that focuses on the interdependencies between barriers and considers the dynamic ways in which barriers develop and persist. Such research, which would be actor-centred and comparative, would help to explain barriers to adaptation and provide insights into how to overcome them.

  16. A model for explaining some features of shuttle glow

    NASA Technical Reports Server (NTRS)

    Peters, P. N.

    1985-01-01

    A solid state model is proposed which hopefully removes some of the objections to excited atoms being sources for light emanating from surfaces. Glow features are discussed in terms of excited oxygen atoms impinged on the surface, although other species could be treated similarly. Band formation, excited lifetime shortening and glow color are discussed in terms of this model. The model's inability to explain glow emanating above surfaces indicates a necessity for other mechanisms to satisfy this requirements. Several ways of testing the model are described.

  17. Dark Matter Explained: Exploring shadows on the cave wall

    NASA Astrophysics Data System (ADS)

    Beichler, James

    2007-04-01

    Science has been faced with an unknown in its theories of the universe for more than two decades. The observed reality of CDM in the galactic halos presents a crisis for science because the present paradigms of physics cannot explain its existence. The quantum solution is to assume that some form of esoteric heavy particles, such as WIMPs, MACHOs or supersymmetry particles, will eventually account for Dark Matter. However, their existence has never been verified. Or a modification of Newton's basic laws of motion called MOND has also been proposed. Yet adding a specialized `fudge-factor' to Newton's fundamental laws of motion merely to save appearances seems questionable. The CDM problem affects gravity theory, not the laws of motion. The problem is relativistic in nature and a relativistic solution is easily found with only a slight change of approach, but that change is radical and not without consequences. The addition of a macroscopically extended fourth spatial dimension to our present four-dimensional space-time world structure explains CDM, but this would amount to the acceptance of the reality of a five-dimensional space-time continuum.

  18. Carcinogenesis explained within the context of a theory of organisms

    PubMed Central

    Sonnenschein, Carlos; Soto, Ana

    2017-01-01

    For a century, the somatic mutation theory (SMT) has been the prevalent theory to explain carcinogenesis. According to the SMT, cancer is a cellular problem, and thus, the level of organization where it should be studied is the cellular level. Additionally, the SMT proposes that cancer is a problem of the control of cell proliferation and assumes that proliferative quiescence is the default state of cells in metazoa. In 1999, a competing theory, the tissue organization field theory (TOFT), was proposed. In contraposition to the SMT, the TOFT posits that cancer is a tissue-based disease whereby carcinogens (directly) and mutations in the germ-line (indirectly) alter the normal interactions between the diverse components of an organ, such as the stroma and its adjacent epithelium. The TOFT explicitly acknowledges that the default state of all cells is proliferation with variation and motility. When taking into consideration the principle of organization, we posit that carcinogenesis can be explained as a relational problem whereby release of the constraints created by cell interactions and the physical forces generated by cellular agency lead cells within a tissue to regain their default state of proliferation with variation and motility. Within this perspective, what matters both in morphogenesis and carcinogenesis is not only molecules, but also biophysical forces generated by cells and tissues. Herein, we describe how the principles for a theory of organisms apply to the TOFT and thus to the study of carcinogenesis. PMID:27498170

  19. A Cerebellar Deficit in Sensorimotor Prediction Explains Movement Timing Variability

    PubMed Central

    Bo, Jin; Block, Hannah J.; Clark, Jane E.; Bastian, Amy J.

    2008-01-01

    A popular theory is that the cerebellum functions as a timer for clocking motor events (e.g., initiation, termination). Consistent with this idea, cerebellar patients have been reported to show greater deficits during hand movements that repeatedly start and stop (i.e., discontinuous movements) compared with continuous hand movements. Yet, this finding could potentially be explained by an alternate theory in which the cerebellum acts as an internal model of limb mechanics. We tested whether a timing or internal model hypothesis best explains results from a circle-drawing task, where individuals trace a circle with the hand at a desired tempo. We first attempted to replicate prior results showing greater impairment for discontinuous versus continuous circling movements, and then asked whether we could improve patient performance by reducing demands in each domain. First, we slowed the movement down to reduce the need to predict and compensate for limb dynamics. Second, we supplied external timing information to reduce the need for an internal event timer. Results showed that we did not replicate the previous findings—cerebellar patients were impaired in both discontinuous and continuous movements. Slowing the movement improved cerebellar performance to near control values. The addition of an external visual timing signal paradoxically worsened timing deficits rather than mitigating them. One interpretation of these combined results is that the cerebellum is indeed functioning as an internal model and is needed to make appropriate predictions for movement initiation and termination. PMID:18815350

  20. A cerebellar deficit in sensorimotor prediction explains movement timing variability.

    PubMed

    Bo, Jin; Block, Hannah J; Clark, Jane E; Bastian, Amy J

    2008-11-01

    A popular theory is that the cerebellum functions as a timer for clocking motor events (e.g., initiation, termination). Consistent with this idea, cerebellar patients have been reported to show greater deficits during hand movements that repeatedly start and stop (i.e., discontinuous movements) compared with continuous hand movements. Yet, this finding could potentially be explained by an alternate theory in which the cerebellum acts as an internal model of limb mechanics. We tested whether a timing or internal model hypothesis best explains results from a circle-drawing task, where individuals trace a circle with the hand at a desired tempo. We first attempted to replicate prior results showing greater impairment for discontinuous versus continuous circling movements, and then asked whether we could improve patient performance by reducing demands in each domain. First, we slowed the movement down to reduce the need to predict and compensate for limb dynamics. Second, we supplied external timing information to reduce the need for an internal event timer. Results showed that we did not replicate the previous findings-cerebellar patients were impaired in both discontinuous and continuous movements. Slowing the movement improved cerebellar performance to near control values. The addition of an external visual timing signal paradoxically worsened timing deficits rather than mitigating them. One interpretation of these combined results is that the cerebellum is indeed functioning as an internal model and is needed to make appropriate predictions for movement initiation and termination.

  1. Can Chunk Size Differences Explain Developmental Changes in Lexical Learning?

    PubMed

    Smalle, Eleonore H M; Bogaerts, Louisa; Simonis, Morgane; Duyck, Wouter; Page, Michael P A; Edwards, Martin G; Szmalec, Arnaud

    2015-01-01

    In three experiments, we investigated Hebb repetition learning (HRL) differences between children and adults, as a function of the type of item (lexical vs. sub-lexical) and the level of item-overlap between sequences. In a first experiment, it was shown that when non-repeating and repeating (Hebb) sequences of words were all permutations of the same words, HRL was slower than when the sequences shared no words. This item-overlap effect was observed in both children and adults. In a second experiment, we used syllable sequences and we observed reduced HRL due to item-overlap only in children. The findings are explained within a chunking account of the HRL effect on the basis of which we hypothesize that children, compared with adults, chunk syllable sequences in smaller units. By hypothesis, small chunks are more prone to interference from anagram representations included in the filler sequences, potentially explaining the item-overlap effect in children. This hypothesis was tested in a third experiment with adults where we experimentally manipulated the chunk size by embedding pauses in the syllable sequences. Interestingly, we showed that imposing a small chunk size caused adults to show the same behavioral effects as those observed in children. Departing from the analogy between verbal HRL and lexical development, the results are discussed in light of the less-is-more hypothesis of age-related differences in language acquisition.

  2. Can model-free reinforcement learning explain deontological moral judgments?

    PubMed

    Ayars, Alisabeth

    2016-05-01

    Dual-systems frameworks propose that moral judgments are derived from both an immediate emotional response, and controlled/rational cognition. Recently Cushman (2013) proposed a new dual-system theory based on model-free and model-based reinforcement learning. Model-free learning attaches values to actions based on their history of reward and punishment, and explains some deontological, non-utilitarian judgments. Model-based learning involves the construction of a causal model of the world and allows for far-sighted planning; this form of learning fits well with utilitarian considerations that seek to maximize certain kinds of outcomes. I present three concerns regarding the use of model-free reinforcement learning to explain deontological moral judgment. First, many actions that humans find aversive from model-free learning are not judged to be morally wrong. Moral judgment must require something in addition to model-free learning. Second, there is a dearth of evidence for central predictions of the reinforcement account-e.g., that people with different reinforcement histories will, all else equal, make different moral judgments. Finally, to account for the effect of intention within the framework requires certain assumptions which lack support. These challenges are reasonable foci for future empirical/theoretical work on the model-free/model-based framework.

  3. Leveraging population admixture to explain missing heritability of complex traits

    PubMed Central

    Zaitlen, Noah; Pasaniuc, Bogdan; Sankararaman, Sriram; Bhatia, Gaurav; Zhang, Jianqi; Gusev, Alexander; Young, Taylor; Tandon, Arti; Pollack, Samuela; Vilhjálmsson, Bjarni J.; Assimes, Themistocles L.; Berndt, Sonja I.; Blot, William J.; Chanock, Stephen; Franceschini, Nora; Goodman, Phyllis G.; He, Jing; Hennis, Anselm JM; Hsing, Ann; Ingles, Sue A.; Isaacs, William; Kittles, Rick A.; Klein, Eric A.; Lange, Leslie A.; Nemesure, Barbara; Patterson, Nick; Reich, David; Rybicki, Benjamin A.; Stanford, Janet L.; Stevens, Victoria L; Strom, Sara S.; Whitsel, Eric A; Witte, John S.; Xu, Jianfeng; Haiman, Christopher; Wilson, James G.; Kooperberg, Charles; Stram, Daniel; Reiner, Alex P.; Tang, Hua; Price, Alkes L.

    2014-01-01

    Despite recent progress on estimating the heritability explained by genotyped SNPs (hg2), a large gap between hg2 and estimates of total narrow-sense heritability (h2) remains. Explanations for this gap include rare variants, or upward bias in family-based estimates of h2 due to shared environment or epistasis. We estimate h2 from unrelated individuals in admixed populations by first estimating the heritability explained by local ancestry (hγ2). We show that hγ2 = 2FSTCθ(1−θ)h2, where FSTC measures frequency differences between populations at causal loci and θ is the genome-wide ancestry proportion. Our approach is not susceptible to biases caused by epistasis or shared environment. We examined 21,497 African Americans from three cohorts, analyzing 13 phenotypes. For height and BMI, we obtained h2 estimates of 0.55 ± 0.09 and 0.23 ± 0.06, respectively, which are larger than estimates of hg2 in these and other data, but smaller than family-based estimates of h2. PMID:25383972

  4. Target Fishing by Cross-Docking to Explain Polypharmacological Effects.

    PubMed

    Patel, Hitesh; Lucas, Xavier; Bendik, Igor; Günther, Stefan; Merfort, Irmgard

    2015-07-01

    Drugs may have polypharmacological phenomena, that is, in addition to the desired target, they may also bind to many undesired or unknown physiological targets. As a result, they often exert side effects. In some cases, off-target interactions may lead to drug repositioning or to explaining a drug's mode of action. Herein we present an in silico approach for target fishing by cross-docking as a method to identify new drug-protein interactions. As an example and proof of concept, this method predicted the peroxisome proliferator-activated receptor (PPAR)-γ as a target of ethacrynic acid, which may explain the hyperglycemic effect brought on by this molecule. The antagonistic effect of ethacrynic acid on PPAR-γ was validated in a transient transactivation assay using human HEK293 cells. The cross-docking approach also predicted the potential mechanisms of many other drug side effects and discloses new drug repositioning opportunities. These putative interactions are described herein, and can be readily used to discover therapeutically relevant drug effects.

  5. How to explain variations in sea cliff erosion rate?

    NASA Astrophysics Data System (ADS)

    Prémaillon, Melody; Regard, Vincent; Dewez, Thomas

    2017-04-01

    Every rocky coast of the world is eroding at different rate (cliff retreat rates). Erosion is caused by a complex interaction of multiple sea weather factors. While numerous local studies exist and explain erosion processes on specific sites, global studies lack. We started to compile many of those local studies and analyse their results with a global point of view in order to quantify the various parameters influencing erosion rates. In other words: is erosion more important in energetic seas? Are chalk cliff eroding faster in rainy environment? etc. In order to do this, we built a database based on literature and national erosion databases. It now contains 80 publications which represents 2500 cliffs studied and more than 3500 erosion rate estimates. A statistical analysis was conducted on this database. On a first approximation, cliff lithology is the only clear signal explaining erosion rate variation: hard lithologies are eroding at 1cm/y or less, whereas unconsolidated lithologies commonly erode faster than 10cm/y. No clear statistical relation were found between erosion rate and external parameters such as sea energy (swell, tide) or weather condition, even on cliff with similar lithology.

  6. Localized bedrock aquifer distribution explains discharge from a headwater catchment

    NASA Astrophysics Data System (ADS)

    Kosugi, Ken'ichirou; Fujimoto, Masamitsu; Katsura, Shin'ya; Kato, Hiroyuki; Sando, Yoshiki; Mizuyama, Takahisa

    2011-07-01

    Understanding a discharge hydrograph is one of the leading interests in catchment hydrology. Recent research has provided credible information on the importance of bedrock groundwater on discharge hydrographs from headwater catchments. However, intensive monitoring of bedrock groundwater is rare in mountains with steep topography. Hence, how bedrock groundwater controls discharge from a steep headwater catchment is in dispute. In this study, we conducted long-term hydrological observations using densely located bedrock wells in a headwater catchment underlain by granitic bedrock. The catchment has steep topography affected by diastrophic activities. Results showed a fairly regionalized distribution of bedrock aquifers within a scale of tens of meters, consisting of upper, middle, and lower aquifers, instead of a gradual and continuous decline in water level from ridge to valley bottom. This was presumably attributable to the unique bedrock structure; fault lines developed in the watershed worked to form divides between the bedrock aquifers. Spatial expanse of each aquifer and the interaction among aquifers were key factors to explain gentle and considerable variations in the base flow discharge and triple-peak discharge responses of the observed hydrograph. A simple model was developed to simulate the discharge hydrograph, which computed each of the contributions from the soil mantle groundwater, from the lower aquifer, and from the middle aquifer to the discharge. The modeling results generally succeeded in reproducing the observed hydrograph. Thus, this study demonstrated that understanding regionalized bedrock aquifer distribution is pivotal for explaining discharge hydrograph from headwater catchments that have been affected by diastrophic activities.

  7. Can evolutionary principles explain patterns of family violence?

    PubMed

    Archer, John

    2013-03-01

    The article's aim is to evaluate the application of the evolutionary principles of kin selection, reproductive value, and resource holding power to the understanding of family violence. The principles are described in relation to specific predictions and the mechanisms underlying these. Predictions are evaluated for physical violence perpetrated by (a) parents to unrelated children, (b) parents to genetic offspring, and (c) offspring to parents and between (d) siblings and (e) sexual partners. Precise figures for risks have been calculated where possible. The major conclusions are that most of the evidence is consistent with evolutionary predictions derived from kin selection and reproductive value: There were (a) higher rates of violence to stepchildren, (b) a decline in violence with the age of offspring, and (c) an increase in violence with parental age, while (d) violence between siblings was generally at a low level and concerned resource disputes. The issue of distinguishing evolutionary from alternative explanations is addressed throughout and is problematic for predictions derived from reproductive value. The main evolutionary explanation for male partner violence, mate guarding as a result of paternity uncertainty, cannot explain Western studies where sex differences in control and violence between partners were absent, although other aspects of male partner violence are consistent with it, and it may explain sex differences in traditional cultures. Recurrent problems in evaluating the evidence were to control for possible confounds and thus to distinguish evolutionary from alternative explanations. Suggestions are outlined to address this and other issues arising from the review. © 2013 American Psychological Association

  8. [Pay for performance explained by transaction costs theory].

    PubMed

    Gorbaneff, Yuri; Cortes, Ariel; Torres, Sergio; Yepes, Francisco

    2011-01-01

    To evaluate the ability of transaction costs theory to explain incentives in the health care chain. We performed a case study of CPS, a health insurance company in Bogota (Colombia), which preferred not to publish its name. CPS moves in the environment of high transaction costs and uses the hybrid form of governance at the outpatient level. Incentive intensity, administrative control and the contract all agree with the theory. At the hospital level, the market is used, despite greater uncertainty. Because of the discrete form (1.0) of the incentives and the absence of administrative control, it is difficult for CPS to relate payment to hospital performance. Transaction costs theory explains the configuration of incentives. Another contribution made by this theory to the literature is the criterion to differentiate between the market and the hybrid. We propose that the market uses discrete-type (1.0) incentives, while the hybrid uses continuous, commission-like incentives. Copyright © 2011 SESPAS. Published by Elsevier Espana. All rights reserved.

  9. Explaining negative kin discrimination in a cooperative mammal society

    PubMed Central

    Cant, Michael A.; Sanderson, Jennifer L.; Gilchrist, Jason S.; Bell, Matthew B. V.; Hodge, Sarah J.; Johnstone, Rufus A.

    2017-01-01

    Kin selection theory predicts that, where kin discrimination is possible, animals should typically act more favorably toward closer genetic relatives and direct aggression toward less closely related individuals. Contrary to this prediction, we present data from an 18-y study of wild banded mongooses, Mungos mungo, showing that females that are more closely related to dominant individuals are specifically targeted for forcible eviction from the group, often suffering severe injury, and sometimes death, as a result. This pattern cannot be explained by inbreeding avoidance or as a response to more intense local competition among kin. Instead, we use game theory to show that such negative kin discrimination can be explained by selection for unrelated targets to invest more effort in resisting eviction. Consistent with our model, negative kin discrimination is restricted to eviction attempts of older females capable of resistance; dominants exhibit no kin discrimination when attempting to evict younger females, nor do they discriminate between more closely or less closely related young when carrying out infanticidal attacks on vulnerable infants who cannot defend themselves. We suggest that in contexts where recipients of selfish acts are capable of resistance, the usual prediction of positive kin discrimination can be reversed. Kin selection theory, as an explanation for social behavior, can benefit from much greater exploration of sequential social interactions. PMID:28439031

  10. Explaining negative kin discrimination in a cooperative mammal society.

    PubMed

    Thompson, Faye J; Cant, Michael A; Marshall, Harry H; Vitikainen, Emma I K; Sanderson, Jennifer L; Nichols, Hazel J; Gilchrist, Jason S; Bell, Matthew B V; Young, Andrew J; Hodge, Sarah J; Johnstone, Rufus A

    2017-05-16

    Kin selection theory predicts that, where kin discrimination is possible, animals should typically act more favorably toward closer genetic relatives and direct aggression toward less closely related individuals. Contrary to this prediction, we present data from an 18-y study of wild banded mongooses, Mungos mungo, showing that females that are more closely related to dominant individuals are specifically targeted for forcible eviction from the group, often suffering severe injury, and sometimes death, as a result. This pattern cannot be explained by inbreeding avoidance or as a response to more intense local competition among kin. Instead, we use game theory to show that such negative kin discrimination can be explained by selection for unrelated targets to invest more effort in resisting eviction. Consistent with our model, negative kin discrimination is restricted to eviction attempts of older females capable of resistance; dominants exhibit no kin discrimination when attempting to evict younger females, nor do they discriminate between more closely or less closely related young when carrying out infanticidal attacks on vulnerable infants who cannot defend themselves. We suggest that in contexts where recipients of selfish acts are capable of resistance, the usual prediction of positive kin discrimination can be reversed. Kin selection theory, as an explanation for social behavior, can benefit from much greater exploration of sequential social interactions.

  11. Epigenetics and obesity: a relationship waiting to be explained.

    PubMed

    Symonds, Michael E; Budge, Helen; Frazier-Wood, Alexis C

    2013-01-01

    Obesity can have multifactorial causes that may change with development and are not simply attributable to one's genetic constitution. To date, expensive and laborious genome-wide association studies have only ascribed a small contribution of genetic variants to obesity. The emergence of the field of epigenetics now offers a new paradigm with which to study excess fat mass. Currently, however, there are no compelling epigenetic studies to explain the role of epigenetics in obesity, especially from a developmental perspective. It is clear that until there are advances in the understanding of the main mechanisms by which different fat types, i.e. brown, beige, and white, are established and how these differ between depots and species, population-based studies designed to determine specific aspects of epigenetics will be potentially limited. Obesity is a slowly evolving condition that is not simply explained by changes in the intake of one macronutrient. The latest advances in epigenetics, coupled with the establishment of relevant longitudinal models of obesity, which incorporate functionally relevant end points, may now permit the precise contribution of epigenetic modifications to excess fat mass to be effectively studied. © 2013 S. Karger AG, Basel.

  12. Health literacy explains racial disparities in diabetes medication adherence.

    PubMed

    Osborn, Chandra Y; Cavanaugh, Kerri; Wallston, Kenneth A; Kripalani, Sunil; Elasy, Tom A; Rothman, Russell L; White, Richard O

    2011-01-01

    Although low health literacy and suboptimal medication adherence are more prevalent in racial/ethnic minority groups than Whites, little is known about the relationship between these factors in adults with diabetes, and whether health literacy or numeracy might explain racial/ethnic disparities in diabetes medication adherence. Previous work in HIV suggests health literacy mediates racial differences in adherence to antiretroviral treatment, but no study to date has explored numeracy as a mediator of the relationship between race/ethnicity and medication adherence. This study tested whether health literacy and/or numeracy were related to diabetes medication adherence, and whether either factor explained racial differences in adherence. Using path analytic models, we explored the predicted pathways between racial status, health literacy, diabetes-related numeracy, general numeracy, and adherence to diabetes medications. After adjustment for covariates, African American race was associated with poor medication adherence (r = -0.10, p < .05). Health literacy was associated with adherence (r = .12, p < .02), but diabetes-related numeracy and general numeracy were not related to adherence. Furthermore, health literacy reduced the effect of race on adherence to nonsignificance, such that African American race was no longer directly associated with lower medication adherence (r = -0.09, p = .14). Diabetes medication adherence promotion interventions should address patient health literacy limitations.

  13. Health Literacy Explains Racial Disparities in Diabetes Medication Adherence

    PubMed Central

    Osborn, Chandra Y.; Cavanaugh, Kerri; Wallston, Kenneth A.; Kripalani, Sunil; White, Richard O.; Elasy, Tom A.; Rothman, Russell L.

    2013-01-01

    While low health literacy and suboptimal medication adherence are more prevalent in racial/ethnic minority groups than Whites, little is known about the relationship between these factors in adults with diabetes, and whether health literacy or numeracy might explain racial/ethnic disparities in diabetes medication adherence. Previous work in HIV suggests health literacy mediates racial differences in adherence to anti-retroviral treatment, but no study to date has explored numeracy as a mediator of the relationship between race/ethnicity and medication adherence. This study tested whether health literacy and/or numeracy were related to diabetes medication adherence, and whether either factor explained racial differences in adherence. Using path analytic models, we explored the predicted pathways between racial status, health literacy, diabetes-related numeracy, general numeracy and adherence to diabetes medications. After adjustment for covariates, African American race was associated with poor medication adherence (r=−0.10, p<0.05). Health literacy was associated with adherence (r=.12, p<0.02), but diabetes-related numeracy and general numeracy were not related to adherence. Furthermore, health literacy reduced the effect of race on adherence to non-significance, such that African American race was no longer directly associated with less medication adherence (r=−0.09, p=.14). Diabetes medication adherence promotion interventions should address patient health literacy limitations. PMID:21951257

  14. Somatic Uniparental Isodisomy Explains Multifocality of Glomuvenous Malformations

    PubMed Central

    Amyere, Mustapha; Aerts, Virginie; Brouillard, Pascal; McIntyre, Brendan A.S.; Duhoux, François P.; Wassef, Michel; Enjolras, Odile; Mulliken, John B.; Devuyst, Olivier; Antoine-Poirel, Hélène; Boon, Laurence M.; Vikkula, Miikka

    2013-01-01

    Inherited vascular malformations are commonly autosomal dominantly inherited with high, but incomplete, penetrance; they often present as multiple lesions. We hypothesized that Knudson’s two-hit model could explain this multifocality and partial penetrance. We performed a systematic analysis of inherited glomuvenous malformations (GVMs) by using multiple approaches, including a sensitive allele-specific pairwise SNP-chip method. Overall, we identified 16 somatic mutations, most of which were not intragenic but were cases of acquired uniparental isodisomy (aUPID) involving chromosome 1p. The breakpoint of each aUPID is located in an A- and T-rich, high-DNA-flexibility region (1p13.1–1p12). This region corresponds to a possible new fragile site. Occurrences of these mutations render the inherited glomulin variant in 1p22.1 homozygous in the affected tissues without loss of genetic material. This finding demonstrates that a double hit is needed to trigger formation of a GVM. It also suggests that somatic UPID, only detectable by sensitive pairwise analysis in heterogeneous tissues, might be a common phenomenon in human cells. Thus, aUPID might play a role in the pathogenesis of various nonmalignant disorders and might explain local impaired function and/or clinical variability. Furthermore, these data suggest that pairwise analysis of blood and tissue, even on heterogeneous tissue, can be used for localizing double-hit mutations in disease-causing genes. PMID:23375657

  15. Context or Composition: What Explains Variation in SCHIP Disenrollment?

    PubMed Central

    Phillips, Julie A; Miller, Jane E; Cantor, Joel C; Gaboda, Dorothy

    2004-01-01

    Objective To investigate (1) the relative contributions of family and contextual characteristics to observed variation in disenrollment rates from the State Children's Health Insurance Program (SCHIP), and (2) whether context explains observed family-level patterns. Data Sources We use secondary data on 24,628 families enrolled in New Jersey's SCHIP program (NJ KidCare), and county-level data from the Area Resource File, the Census, and the NJ FamilyCare provider roster. Study Design Information on family characteristics, SCHIP plan, and dates of enrollment and disenrollment are taken from NJ KidCare administrative records, which provided surveillance data from January 1998 through April 2000. Data Collection/Analysis We estimate a multilevel discrete-time-hazards model of SCHIP disenrollment. Findings Families enrolled in plans involving cost-sharing, blacks, and those with only one enrolled child have higher than average rates of disenrollment. Disenrollment rates for blacks are lower in counties with a high share of black physicians. These characteristics account for part of the intercounty variation in disenrollment rates; remaining intercounty variation is largely explained by physician density or population density. Policy Implications It may be worthwhile to pay special attention to black families and counties with high disenrollment rates to address the reasons for their lower retention. Addressing cultural differences between physician and client and the geographic distribution of medical providers might reduce disenrollment. PMID:15230932

  16. Explaining fruit and vegetable intake using a consumer marketing tool.

    PubMed

    Della, Lindsay J; Dejoy, David M; Lance, Charles E

    2009-10-01

    In response to calls to reinvent the 5 A Day fruit and vegetable campaign, this study assesses the utility of VALS, a consumer-based audience segmentation tool that divides the U.S. population into groups leading similar lifestyles. The study examines whether the impact of theory of planned behavior (TPB) constructs varies across VALS groups in a cross-sectional sample of 1,588 U.S. adults. In a multigroup structural equation model, the VALS audience group variable moderated latent TPB relationships. Attitudes, subjective norms, and perceived behavioral control explained 57% to 70% of the variation in intention to eat fruit and vegetables across 5 different VALS groups. Perceived behavioral control and intention also predicted self-reported consumption behavior (R2 = 20% to 71% across VALS groups). Bivariate z tests were calculated to determine statistical differences in parameter estimates across groups. Nine of the bivariate z tests were statistically significant (p < or = .04), with standardized coefficients ranging from .05 to .70. These findings confirm the efficacy of using the TPB to explain variation in fruit and vegetable consumption as well as the validity of using a consumer-based algorithm to segment audiences for fruit and vegetable consumption messaging.

  17. A unified physical model to explain Supercavity closure

    NASA Astrophysics Data System (ADS)

    Arndt, Roger; Karn, Ashish; Hong, Jiarong

    2014-11-01

    An insight into underlying physics behind supercavity closure is an important issue for the operation of underwater vehicles for a number of reasons viz. associated gas flow requirement with each closure regime, effect of cavity closure on the overall cavity behavior and collapse, differences between natural and ventilated supercavity closure etc. There have been several reports on supercavity closure since the 1950s and many empirical relationships governing different closure modes have been proposed by different authors. Yet, there is no universal agreement between results obtained at different experimental facilities. In some cases, contradictory observations have been made. In this talk, systematic investigations conducted into supercavity closure across a wide range of experimental conditions at the Saint Anthony Falls Laboratory (SAFL) are presented. A variety of closure mechanisms were observed including the ones widely reported in the literature, viz. twin vortex, re-entrant jet; new stable closure modes viz. quad vortex and interacting vortex and a host of transition closure modes. A hypothesis on the physical mechanism based on the pressure gradient across the cavity that determines the closure modes is proposed. Using this hypothesis and the control volume analysis at supercavity closure, we explain the observations from SAFL experiments as well as reconcile the observations reported by different researchers. The hypothesis explains the supercavity closure across different experimental facilities, at different blockage ratios and at different flow conditions. Thus, a unified understanding into supercavity closure from the viewpoint of fundamental physics is attempted. Supported by the Office Of Naval Research.

  18. Carcinogenesis explained within the context of a theory of organisms.

    PubMed

    Sonnenschein, Carlos; Soto, Ana M

    2016-10-01

    For a century, the somatic mutation theory (SMT) has been the prevalent theory to explain carcinogenesis. According to the SMT, cancer is a cellular problem, and thus, the level of organization where it should be studied is the cellular level. Additionally, the SMT proposes that cancer is a problem of the control of cell proliferation and assumes that proliferative quiescence is the default state of cells in metazoa. In 1999, a competing theory, the tissue organization field theory (TOFT), was proposed. In contraposition to the SMT, the TOFT posits that cancer is a tissue-based disease whereby carcinogens (directly) and mutations in the germ-line (indirectly) alter the normal interactions between the diverse components of an organ, such as the stroma and its adjacent epithelium. The TOFT explicitly acknowledges that the default state of all cells is proliferation with variation and motility. When taking into consideration the principle of organization, we posit that carcinogenesis can be explained as a relational problem whereby release of the constraints created by cell interactions and the physical forces generated by cellular agency lead cells within a tissue to regain their default state of proliferation with variation and motility. Within this perspective, what matters both in morphogenesis and carcinogenesis is not only molecules, but also biophysical forces generated by cells and tissues. Herein, we describe how the principles for a theory of organisms apply to the TOFT and thus to the study of carcinogenesis.

  19. CAN SOLID BODY DESTRUCTION EXPLAIN ABUNDANCE DISCREPANCIES IN PLANETARY NEBULAE?

    SciTech Connect

    Henney, William J.; Stasinska, Grazyna E-mail: grazyna.stasinska@obspm.f

    2010-03-10

    In planetary nebulae (PNe), abundances of oxygen and other heavy elements derived from optical recombination lines are systematically higher than those derived from collisionally excited lines. We investigate the hypothesis that the destruction of solid bodies may produce pockets of cool, high-metallicity gas that could explain these abundance discrepancies. Under the assumption of maximally efficient radiative ablation, we derive two fundamental constraints that the solid bodies must satisfy in order that their evaporation during the PN phase should generate a high enough gas-phase metallicity. A local constraint implies that the bodies must be larger than tens of meters, while a global constraint implies that the total mass of the solid body reservoir must exceed a few hundredths of a solar mass. This mass greatly exceeds the mass of any population of comets or large debris particles expected to be found orbiting evolved low- to intermediate-mass stars. We therefore conclude that contemporaneous solid body destruction cannot explain the observed abundance discrepancies in PNe. However, similar arguments applied to the sublimation of solid bodies during the preceding asymptotic giant branch phase do not lead to such a clear-cut conclusion. In this case, the required reservoir of volatile solids is only one ten-thousandth of a solar mass, which is comparable to the most massive debris disks observed around solar-type stars, implying that this mechanism may contribute to abundance discrepancies in at least some PNe, so long as mixing of the high-metallicity gas is inefficient.

  20. Can Chunk Size Differences Explain Developmental Changes in Lexical Learning?

    PubMed Central

    Smalle, Eleonore H. M.; Bogaerts, Louisa; Simonis, Morgane; Duyck, Wouter; Page, Michael P. A.; Edwards, Martin G.; Szmalec, Arnaud

    2016-01-01

    In three experiments, we investigated Hebb repetition learning (HRL) differences between children and adults, as a function of the type of item (lexical vs. sub-lexical) and the level of item-overlap between sequences. In a first experiment, it was shown that when non-repeating and repeating (Hebb) sequences of words were all permutations of the same words, HRL was slower than when the sequences shared no words. This item-overlap effect was observed in both children and adults. In a second experiment, we used syllable sequences and we observed reduced HRL due to item-overlap only in children. The findings are explained within a chunking account of the HRL effect on the basis of which we hypothesize that children, compared with adults, chunk syllable sequences in smaller units. By hypothesis, small chunks are more prone to interference from anagram representations included in the filler sequences, potentially explaining the item-overlap effect in children. This hypothesis was tested in a third experiment with adults where we experimentally manipulated the chunk size by embedding pauses in the syllable sequences. Interestingly, we showed that imposing a small chunk size caused adults to show the same behavioral effects as those observed in children. Departing from the analogy between verbal HRL and lexical development, the results are discussed in light of the less-is-more hypothesis of age-related differences in language acquisition. PMID:26779065

  1. Can vertebral density changes be explained by intervertebral disc degeneration?

    PubMed

    Homminga, Jasper; Aquarius, Rene; Bulsink, Vera E; Jansen, Christiaan T J; Verdonschot, Nico

    2012-05-01

    One of the major problems facing the elderly spine is the occurrence of vertebral fractures due to low bone mass. Although typically attributed to osteoporosis, disc degeneration has also been suggested to play a role in vertebral fractures. Existing bone adaptation theories and simulations may explain the biomechanical pathway from a degenerated disc to an increased fracture risk. A finite element model of a lumbar segment was created and calibrated. Subsequently the disc properties were varied to represent either a healthy or degenerated disc and the resulting bone adaptation was simulated. Disc degeneration resulted in a shift of load from the nucleus to the annulus. The resulting bone adaptation led to a dramatically reduced density of the trabecular core and to an increased density in the vertebral walls. Degeneration of just the nucleus, and in particular the dehydration of the nucleus, resulted in most of this bone density change. Additional annulus degeneration had much less of an effect on the density values. The density decrease in the trabecular core as seen in this study matches clinical observations. Therefore, bone remodeling theories can assists in explaining the potential synergistic effects of disc degeneration and osteoporotis in the occurrence of vertebral fractures. Copyright © 2011 IPEM. Published by Elsevier Ltd. All rights reserved.

  2. Reinforcement Learning Explains Conditional Cooperation and Its Moody Cousin.

    PubMed

    Ezaki, Takahiro; Horita, Yutaka; Takezawa, Masanori; Masuda, Naoki

    2016-07-01

    Direct reciprocity, or repeated interaction, is a main mechanism to sustain cooperation under social dilemmas involving two individuals. For larger groups and networks, which are probably more relevant to understanding and engineering our society, experiments employing repeated multiplayer social dilemma games have suggested that humans often show conditional cooperation behavior and its moody variant. Mechanisms underlying these behaviors largely remain unclear. Here we provide a proximate account for this behavior by showing that individuals adopting a type of reinforcement learning, called aspiration learning, phenomenologically behave as conditional cooperator. By definition, individuals are satisfied if and only if the obtained payoff is larger than a fixed aspiration level. They reinforce actions that have resulted in satisfactory outcomes and anti-reinforce those yielding unsatisfactory outcomes. The results obtained in the present study are general in that they explain extant experimental results obtained for both so-called moody and non-moody conditional cooperation, prisoner's dilemma and public goods games, and well-mixed groups and networks. Different from the previous theory, individuals are assumed to have no access to information about what other individuals are doing such that they cannot explicitly use conditional cooperation rules. In this sense, myopic aspiration learning in which the unconditional propensity of cooperation is modulated in every discrete time step explains conditional behavior of humans. Aspiration learners showing (moody) conditional cooperation obeyed a noisy GRIM-like strategy. This is different from the Pavlov, a reinforcement learning strategy promoting mutual cooperation in two-player situations.

  3. Mycorrhizal status helps explain invasion success of alien plant species.

    PubMed

    Menzel, Andreas; Hempel, Stefan; Klotz, Stefan; Moora, Mari; Pyšek, Petr; Rillig, Matthias C; Zobel, Martin; Kühn, Ingolf

    2017-01-01

    It is still debated whether alien plants benefit from being mycorrhizal, or if engaging in the symbiosis constrains their establishment and spread in new regions. We analyzed the association between mycorrhizal status of alien plant species in Germany and their invasion success. We compared whether the representation of species with different mycorrhizal status (obligate, facultative, or non-mycorrhizal) differed at several stages of the invasion process. We used generalized linear models to explain the occupied geographical range of alien plants, incorporating interactions of mycorrhizal status with plant traits related to morphology, reproduction, and life-history. Non-naturalized aliens did not differ from naturalized aliens in the relative frequency of different mycorrhizal status categories. Mycorrhizal status significantly explained the occupied range of alien plants; with facultative mycorrhizal species inhabiting a larger range than non-mycorrhizal aliens and obligate mycorrhizal plant species taking an intermediate position. Aliens with storage organs, shoot metamorphoses, or specialized structures promoting vegetative dispersal occupied a larger range when being facultative mycorrhizal. We conclude that being mycorrhizal is important for the persistence of aliens in Germany and constitutes an advantage compared to being non-mycorrhizal. Being facultative mycorrhizal seems to be especially advantageous for successful spread, as the flexibility of this mycorrhizal status may enable plants to use a broader set of ecological strategies. © 2016 by the Ecological Society of America.

  4. Male reproductive strategy explains spatiotemporal segregation in brown bears.

    PubMed

    Steyaert, Sam M J G; Kindberg, Jonas; Swenson, Jon E; Zedrosser, Andreas

    2013-07-01

    Spatiotemporal segregation is often explained by the risk for offspring predation or by differences in physiology, predation risk vulnerability or competitive abilities related to size dimorphism. Most large carnivores are size dimorphic and offspring predation is often intraspecific and related to nonparental infanticide (NPI). NPI can be a foraging strategy, a strategy to reduce competition, or a male reproductive strategy. Spatiotemporal segregation is widespread among large carnivores, but its nature remains poorly understood. We evaluated three hypotheses to explain spatiotemporal segregation in the brown bear, a size-dimorphic large carnivore in which NPI is common; the 'NPI - foraging/competition hypothesis', i.e. NPI as a foraging strategy or a strategy to reduce competition, the 'NPI - sexual selection hypothesis', i.e. infanticide as a male reproductive strategy and the 'body size hypothesis', i.e. body-size-related differences in physiology, predation risk vulnerability or competitive ability causes spatiotemporal segregation. To test these hypotheses, we quantified spatiotemporal segregation among adult males, lone adult females and females with cubs-of-the-year, based on GPS-relocation data (2006-2010) and resource selection functions in a Scandinavian population. We found that spatiotemporal segregation was strongest between females with cubs-of-the-year and adult males during the mating season. During the mating season, females with cubs-of-the-year selected their resources, in contrast to adult males, in less rugged landscapes in relative close proximity to certain human-related variables, and in more open habitat types. After the mating season, females with cubs-of-the-year markedly shifted their resource selection towards a pattern more similar to that of their conspecifics. No strong spatiotemporal segregation was apparent between females with cubs-of-the-year and conspecifics during the mating and the postmating season. The 'NPI - sexual

  5. Explaining the discrepancy between forced fold amplitude and sill thickness.

    NASA Astrophysics Data System (ADS)

    Hoggett, Murray; Jones, Stephen M.; Reston, Timothy; Magee, Craig; Jackson, Christopher AL

    2017-04-01

    Understanding the behaviour of Earth's surface in response to movement and emplacement of magma underground is important because it assists calculation of subsurface magma volumes, and could feed into eruption forecasting. Studies of seismic reflection data have observed that the amplitude of a forced fold above an igneous sill is usually smaller than the thickness of the sill itself. This observation implies that fold amplitude alone provides only a lower bound for magma volume, and an understanding of the mechanism(s) behind the fold amplitude/sill thickness discrepancy is also required to obtain a true estimate of magma volume. Mechanisms suggested to explain the discrepancy include problems with seismic imaging and varying strain behaviour of the host rock. Here we examine the extent to which host-rock compaction can explain the fold amplitude/sill thickness discrepancy. This mechanism operates in cases where a sill is injected into the upper few kilometres of sedimentary rock that contain significant porosity. Accumulation of sediment after sill intrusion reduces the amplitude of the forced fold by compaction, but the sill itself undergoes little compaction since its starting porosity is almost zero. We compiled a database of good-quality 2D and 3D seismic observations where sill thickness has been measured independently of forced fold geometry. We then backstripped the post-intrusion sedimentary section to reconstruct the amplitude of the forced fold at the time of intrusion. We used the standard compaction model in which porosity decays exponentially below the sediment surface. In all examples we studied, post-sill-emplacement compaction can explain all of the fold amplitude/sill thickness discrepancy, subject to uncertainty in compaction model parameters. This result leads directly to an improved method of predicting magma volume from fold amplitude, including how uncertainty in compaction parameters maps onto uncertainty in magma volume. Our work implies

  6. EARTHSHINE ON A YOUNG MOON: EXPLAINING THE LUNAR FARSIDE HIGHLANDS

    SciTech Connect

    Roy, Arpita; Wright, Jason T.; Sigurðsson, Steinn

    2014-06-20

    The lunar farside highlands problem refers to the curious and unexplained fact that the farside lunar crust is thicker, on average, than the nearside crust. Here we recognize the crucial influence of Earthshine, and propose that it naturally explains this hemispheric dichotomy. Since the accreting Moon rapidly achieved synchronous rotation, a surface and atmospheric thermal gradient was imposed by the proximity of the hot, post-giant impact Earth. This gradient guided condensation of atmospheric and accreting material, preferentially depositing crust-forming refractories on the cooler farside, resulting in a primordial bulk chemical inhomogeneity that seeded the crustal asymmetry. Our model provides a causal solution to the lunar highlands problem: the thermal gradient created by Earthshine produced the chemical gradient responsible for the crust thickness dichotomy that defines the lunar highlands.

  7. "Developmental capture" of the state: explaining Thailand's universal coverage policy.

    PubMed

    Harris, Joseph

    2015-02-01

    The notion of "regulatory capture" is typically used to describe the takeover of state agencies by outside interest groups that seek to weaken regulation and advance the agendas of interest groups through control over state policy levers. This concept can be contrasted with that of "developmental capture" of state agencies by networks of reformist bureaucrats within the state who seek to promote inclusive state social and developmental policies of benefit to the broader populace. Building on work that has pointed to instances in which state bureaucrats act autonomously from societal and political pressures, this article argues that existing explanations are insufficient for explaining Thailand's universal health care policy. It points to the critical role played by a network of bureaucrats within the state who strategically mobilized resources in the bureaucracy, political parties, civil society, and international organizations to institutionalize universal health care in the face of broader professional dissent, political uncertainty, and international pressure.

  8. Explaining drug policy: Towards an historical sociology of policy change.

    PubMed

    Seddon, Toby

    2011-11-01

    The goal of seeking to understand the development over time of drug policies is a specific version of the more general intellectual project of finding ways of explaining social change. The latter has been a preoccupation of some of the greatest thinkers within the social sciences of the last 200 years, from Foucault all the way back to the three nineteenth-century pioneers, Marx, Durkheim and Weber. I describe this body of work as 'historical sociology'. In this paper, I outline how a particular approach to historical sociology can be fruitfully drawn upon to understand the development of drug policy, using by way of illustration the example of the analysis of a recent transformation in British drug policy: the rise of the criminal justice agenda. I conclude by arguing that by looking at developments in drug policy in this way, some new insights are opened up. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Carbonatite ring-complexes explained by caldera-style volcanism

    PubMed Central

    Andersson, Magnus; Malehmir, Alireza; Troll, Valentin R.; Dehghannejad, Mahdieh; Juhlin, Christopher; Ask, Maria

    2013-01-01

    Carbonatites are rare, carbonate-rich magmatic rocks that make up a minute portion of the crust only, yet they are of great relevance for our understanding of crustal and mantle processes. Although they occur in all continents and from Archaean to present, the deeper plumbing system of carbonatite ring-complexes is usually poorly constrained. Here, we show that carbonatite ring-complexes can be explained by caldera-style volcanism. Our geophysical investigation of the Alnö carbonatite ring-complex in central Sweden identifies a solidified saucer-shaped magma chamber at ~3 km depth that links to surface exposures through a ring fault system. Caldera subsidence during final stages of activity caused carbonatite eruptions north of the main complex, providing the crucial element to connect plutonic and eruptive features of carbonatite magmatism. The way carbonatite magmas are stored, transported and erupt at the surface is thus comparable to known emplacement styles from silicic calderas. PMID:23591904

  10. Explaining PAH desorption from sediments using Rock Eval analysis.

    PubMed

    Poot, Anton; Jonker, M T O; Gillissen, Frits; Koelmans, Albert A

    2014-10-01

    Here, we provide Rock Eval and black carbon (BC) characteristics and polycyclic aromatic hydrocarbon (PAH) distribution coefficients (KD) for sediments from the Danube, Elbe, Ebro, and Meuse river basins. PAH desorption kinetic parameters were determined using sequential Tenax extractions. We show that residual carbon (RC) from Rock Eval analysis is an adequate predictor of fast, slow, and very slow desorbing fractions of 4-ring PAHs. RC correlated better than BC, the latter constituting only 7% of RC. A dual domain sorption model was statistically superior to a single domain model in explaining KD for low molecular weight PAHs, whereas the opposite was observed for high molecular weight PAHs. Because particularly the 4-ring PAHs are bioavailable and relevant from a risk assessment perspective and because their fast desorbing fractions correlate best with RC, we recommend RC as a relevant characteristic for river sediments.

  11. [Nurses are not into personal marketing: do history explain why?].

    PubMed

    Gentil, Rosana Chami

    2009-01-01

    Reflection on the nurse's personal marketing based on beliefs and values explained by the history of the main characters that care for patients. It brings to the surface reflections on the ambiguity between the social image of nursing and scientific, technological and humanistic knowledge developed over the time. It recognizes that there is still a fixation on the attributes relating to attitude and moral of the professionals to the detriment of having high regard for the technical and scientific knowledge. It verifies that the History of Nursing allows understanding that the fight against prejudice in the collective imagination lends weight to the social acceptance and recognition of this profession through the promotion of Nursing Science and the demonstration of its application in the professional practice.

  12. Social inheritance can explain the structure of animal social networks

    PubMed Central

    Ilany, Amiyaal; Akçay, Erol

    2016-01-01

    The social network structure of animal populations has major implications for survival, reproductive success, sexual selection and pathogen transmission of individuals. But as of yet, no general theory of social network structure exists that can explain the diversity of social networks observed in nature, and serve as a null model for detecting species and population-specific factors. Here we propose a simple and generally applicable model of social network structure. We consider the emergence of network structure as a result of social inheritance, in which newborns are likely to bond with maternal contacts, and via forming bonds randomly. We compare model output with data from several species, showing that it can generate networks with properties such as those observed in real social systems. Our model demonstrates that important observed properties of social networks, including heritability of network position or assortative associations, can be understood as consequences of social inheritance. PMID:27352101

  13. Microeconomic principles explain an optimal genome size in bacteria.

    PubMed

    Ranea, Juan A G; Grant, Alastair; Thornton, Janet M; Orengo, Christine A

    2005-01-01

    Bacteria can clearly enhance their survival by expanding their genetic repertoire. However, the tight packing of the bacterial genome and the fact that the most evolved species do not necessarily have the biggest genomes suggest there are other evolutionary factors limiting their genome expansion. To clarify these restrictions on size, we studied those protein families contributing most significantly to bacterial-genome complexity. We found that all bacteria apply the same basic and ancestral 'molecular technology' to optimize their reproductive efficiency. The same microeconomics principles that define the optimum size in a factory can also explain the existence of a statistical optimum in bacterial genome size. This optimum is reached when the bacterial genome obtains the maximum metabolic complexity (revenue) for minimal regulatory genes (logistic cost).

  14. Explaining social discrimination: racism in Brazil and xenophobia in Spain.

    PubMed

    Camino, Leoncio; Álvaro, José Luis; Torres, Ana Raquel R; Garrido, Alicia; Morais, Thiago; Barbosa, Juliana

    2013-01-01

    The present study investigates the arguments used by university students in order to explain social differences between social minorities and majorities. In Brazil, the issues investigated refer to White and Black people. In Spain, the reference is to native Spaniards and Moroccan immigrants. The participants were 144 Brazilians and 93 Spaniards, who answered a questionnaire composed of socio-demographic variables and one open question about the causes of social inequalities between Black and White people in Brazil and between autochthonous Spaniards and Moroccan Immigrants. A model is proposed to integrate the four discursive classes found using ALCESTE software. In Brazil, the strongest argument is based on the historical roots of the exploitation of Black people. In Spain, cultural differences are the main explanation for social inequalities.

  15. Jumping Jupiter Can Explain Mercury’s Orbit

    NASA Astrophysics Data System (ADS)

    Roig, Fernando; Nesvorný, David; DeSouza, Sandro Ricardo

    2016-04-01

    The orbit of Mercury has large values of eccentricity and inclination that cannot be easily explained if this planet formed on a circular and coplanar orbit. Here, we study the evolution of Mercury’s orbit during the instability related to the migration of the giant planets in the framework of the jumping-Jupiter model. We found that some instability models are able to produce the correct values of Mercury’s eccentricity and inclination, provided that relativistic effects are included in the precession of Mercury’s perihelion. The orbital excitation is driven by the fast change of the normal oscillation modes of the system corresponding to the perihelion precession of Jupiter (for the eccentricity) and the nodal regression of Uranus (for the inclination).

  16. Real world ocean rogue waves explained without the modulational instability

    NASA Astrophysics Data System (ADS)

    Fedele, Francesco; Brennan, Joseph; Ponce de León, Sonia; Dudley, John; Dias, Frédéric

    2016-06-01

    Since the 1990s, the modulational instability has commonly been used to explain the occurrence of rogue waves that appear from nowhere in the open ocean. However, the importance of this instability in the context of ocean waves is not well established. This mechanism has been successfully studied in laboratory experiments and in mathematical studies, but there is no consensus on what actually takes place in the ocean. In this work, we question the oceanic relevance of this paradigm. In particular, we analyze several sets of field data in various European locations with various tools, and find that the main generation mechanism for rogue waves is the constructive interference of elementary waves enhanced by second-order bound nonlinearities and not the modulational instability. This implies that rogue waves are likely to be rare occurrences of weakly nonlinear random seas.

  17. The Cholodny-Went theory does not explain hydrotropism.

    PubMed

    Shkolnik, Doron; Fromm, Hillel

    2016-11-01

    Optimization of water foraging by plants is partially achieved by the ability of roots to direct growth towards high water potential, a phenomenon termed hydrotropism. In contrast to gravitropism and phototropism, which require auxin redistribution, as suggested by the Cholodny-Went theory, hydrotropism is not mediated by the phytohormone auxin, which raises questions about the mechanism underlying this tropic response. Here we specify the open questions in this field of research and discuss the possible interactions of abscisic acid, calcium and reactive oxygen species as part of a dynamic system of sensing water potential in the root tip, transmission of the signal to the root elongation zone and promoting root curvature towards water. We conclude that root hydrotropism is mediated by inter-cellular signals that are not explained by the Cholodny-Went theory. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  18. Heterogeneity explains features of “anomalous” thermodynamics and statistics

    PubMed Central

    Gheorghiu, Stefan; Coppens, Marc-Olivier

    2004-01-01

    Phenomena characterized by power-law probability distributions abound in nature and the applied sciences. We show that many of these power laws are well described by the Student, or t, distribution, and we discuss the origin of this universality based on three examples (Brownian motion, Knudsen diffusion in rough pores, and bubbly multiphase flow). These case studies are representative for a large class of systems with heterogeneous features, examples of which can be found from Earth sciences to astrophysics, and even in the social sciences. We show that common forms of polydispersity, such as polydispersity arising naturally as a result of aggregation–fragmentation phenomena, typically lie at the basis of the observed scaling. We conclude that complicated arguments based on long-range correlations or nonergodicity are often incorrect or misleading in explaining many naturally observed power laws and, in particular, those described by the Student distribution. PMID:15514018

  19. Real world ocean rogue waves explained without the modulational instability

    PubMed Central

    Fedele, Francesco; Brennan, Joseph; Ponce de León, Sonia; Dudley, John; Dias, Frédéric

    2016-01-01

    Since the 1990s, the modulational instability has commonly been used to explain the occurrence of rogue waves that appear from nowhere in the open ocean. However, the importance of this instability in the context of ocean waves is not well established. This mechanism has been successfully studied in laboratory experiments and in mathematical studies, but there is no consensus on what actually takes place in the ocean. In this work, we question the oceanic relevance of this paradigm. In particular, we analyze several sets of field data in various European locations with various tools, and find that the main generation mechanism for rogue waves is the constructive interference of elementary waves enhanced by second-order bound nonlinearities and not the modulational instability. This implies that rogue waves are likely to be rare occurrences of weakly nonlinear random seas. PMID:27323897

  20. Using Literature-Based Discovery to Explain Adverse Drug Effects.

    PubMed

    Hristovski, Dimitar; Kastrin, Andrej; Dinevski, Dejan; Burgun, Anita; Žiberna, Lovro; Rindflesch, Thomas C

    2016-08-01

    We report on our research in using literature-based discovery (LBD) to provide pharmacological and/or pharmacogenomic explanations for reported adverse drug effects. The goal of LBD is to generate novel and potentially useful hypotheses by analyzing the scientific literature and optionally some additional resources. Our assumption is that drugs have effects on some genes or proteins and that these genes or proteins are associated with the observed adverse effects. Therefore, by using LBD we try to find genes or proteins that link the drugs with the reported adverse effects. These genes or proteins can be used to provide insight into the processes causing the adverse effects. Initial results show that our method has the potential to assist in explaining reported adverse drug effects.

  1. Explaining Society: An Expanded Toolbox for Social Scientists

    PubMed Central

    Bell, David C.; Atkinson-Schnell, Jodie L.; DiBacco, Aron E.

    2012-01-01

    We propose for social scientists a theoretical toolbox containing a set of motivations that neurobiologists have recently validated. We show how these motivations can be used to create a theory of society recognizably similar to existing stable societies (sustainable, self-reproducing, and largely peaceful). Using this toolbox, we describe society in terms of three institutions: economy (a source of sustainability), government (peace), and the family (reproducibility). Conducting a thought experiment in three parts, we begin with a simple theory with only two motivations. We then create successive theories that systematically add motivations, showing that each element in the toolbox makes its own contribution to explain the workings of a stable society and that the family has a critical role in this process. PMID:23082093

  2. Visual Representation Determines Search Difficulty: Explaining Visual Search Asymmetries

    PubMed Central

    Bruce, Neil D. B.; Tsotsos, John K.

    2011-01-01

    In visual search experiments there exist a variety of experimental paradigms in which a symmetric set of experimental conditions yields asymmetric corresponding task performance. There are a variety of examples of this that currently lack a satisfactory explanation. In this paper, we demonstrate that distinct classes of asymmetries may be explained by virtue of a few simple conditions that are consistent with current thinking surrounding computational modeling of visual search and coding in the primate brain. This includes a detailed look at the role that stimulus familiarity plays in the determination of search performance. Overall, we demonstrate that all of these asymmetries have a common origin, namely, they are a consequence of the encoding that appears in the visual cortex. The analysis associated with these cases yields insight into the problem of visual search in general and predictions of novel search asymmetries. PMID:21808617

  3. Quantum metabolism explains the allometric scaling of metabolic rates.

    PubMed

    Demetrius, Lloyd; Tuszynski, J A

    2010-03-06

    A general model explaining the origin of allometric laws of physiology is proposed based on coupled energy-transducing oscillator networks embedded in a physical d-dimensional space (d = 1, 2, 3). This approach integrates Mitchell's theory of chemi-osmosis with the Debye model of the thermal properties of solids. We derive a scaling rule that relates the energy generated by redox reactions in cells, the dimensionality of the physical space and the mean cycle time. Two major regimes are found corresponding to classical and quantum behaviour. The classical behaviour leads to allometric isometry while the quantum regime leads to scaling laws relating metabolic rate and body size that cover a broad range of exponents that depend on dimensionality and specific parameter values. The regimes are consistent with a range of behaviours encountered in micelles, plants and animals and provide a conceptual framework for a theory of the metabolic function of living systems.

  4. Quantum metabolism explains the allometric scaling of metabolic rates

    PubMed Central

    Demetrius, Lloyd; Tuszynski, J. A.

    2010-01-01

    A general model explaining the origin of allometric laws of physiology is proposed based on coupled energy-transducing oscillator networks embedded in a physical d-dimensional space (d = 1, 2, 3). This approach integrates Mitchell's theory of chemi-osmosis with the Debye model of the thermal properties of solids. We derive a scaling rule that relates the energy generated by redox reactions in cells, the dimensionality of the physical space and the mean cycle time. Two major regimes are found corresponding to classical and quantum behaviour. The classical behaviour leads to allometric isometry while the quantum regime leads to scaling laws relating metabolic rate and body size that cover a broad range of exponents that depend on dimensionality and specific parameter values. The regimes are consistent with a range of behaviours encountered in micelles, plants and animals and provide a conceptual framework for a theory of the metabolic function of living systems. PMID:19734187

  5. Explaining and forecasting attrition in the Army pharmacy technician course.

    PubMed

    Fulton, Larry; Starnes, L William; Caouette, Marc; Whittaker, Donna; Ivanitskaya, Lana

    2008-12-01

    The Army pharmacy technician (68Q) course trains--260 students per year, with a mean graduation rate of 71.3%. In support of this course, a research team conducted a study using multiple analytical methods to evaluate, to explain, and potentially to forecast failures, because the 28.7% of students who do not graduate are associated with both opportunity and real costs. Results of this study indicated that largely uncontrollable population demographic characteristics, such as rank and enrollment status, along with controllable Armed Services Vocational Aptitude Battery skilled technical test scores, were related to graduation rates. The results of this study may be used to assist individuals at risk of failure or to establish additional admission criteria to increase the likelihood of success.

  6. Explaining prompts children to privilege inductively rich properties.

    PubMed

    Walker, Caren M; Lombrozo, Tania; Legare, Cristine H; Gopnik, Alison

    2014-11-01

    Four experiments with preschool-aged children test the hypothesis that engaging in explanation promotes inductive reasoning on the basis of shared causal properties as opposed to salient (but superficial) perceptual properties. In Experiments 1a and 1b, 3- to 5-year-old children prompted to explain during a causal learning task were more likely to override a tendency to generalize according to perceptual similarity and instead extend an internal feature to an object that shared a causal property. Experiment 2 replicated this effect of explanation in a case of label extension (i.e., categorization). Experiment 3 demonstrated that explanation improves memory for clusters of causally relevant (non-perceptual) features, but impairs memory for superficial (perceptual) features, providing evidence that effects of explanation are selective in scope and apply to memory as well as inference. In sum, our data support the proposal that engaging in explanation influences children's reasoning by privileging inductively rich, causal properties.

  7. Explaining the RK and RD(*) anomalies with vector leptoquarks

    NASA Astrophysics Data System (ADS)

    Sahoo, Suchismita; Mohanta, Rukmani; Giri, Anjan K.

    2017-02-01

    Recently, the B factories BABAR and Belle as well as the LHCb experiment have reported several anomalies in the semileptonic B meson decays, such as the RK and RD(*) etc. We investigate these deviations by considering the vector leptoquarks relevant for both b →s l+l- and b →c l ν¯ l transitions. The leptoquark parameter space is constrained by using the experimentally measured branching ratios of Bs→l+l- , B ¯ →Xsl+l-(ν ν ¯ ) , and Bu+→l+νl processes. Using the constrained leptoquark couplings, we compute the branching ratios, forward-backward asymmetries, τ , and D* polarization parameters in the B ¯ →D(*)l ν¯ l processes. We find that the vector leptoquarks can explain both the RD(*) and RK anomalies, simultaneously. Furthermore, we study the rare leptonic Bu,c *→l ν ¯ decay processes in this model.

  8. Explanations in knowledge systems - Design for Explainable Expert Systems

    NASA Technical Reports Server (NTRS)

    Swartout, William; Paris, Cecile; Moore, Johanna

    1991-01-01

    The Explainable Expert Systems framework (EES), in which the focus is on capturing those design aspects that are important for producing good explanations, including justifications of the system's actions, explications of general problem-solving strategies, and descriptions of the system's terminology, is discussed. EES was developed as part of the Strategic Computing Initiative of DARPA. Both the general principles from which the system was derived and how the system was derived from those principles can be represented in EES. The Program Enhancement Advisor, which is the main prototype on which the explanation work has been developed and tested, is presented. PEA is an advice system that helps users improve their Common Lisp programs by recommending transformations that enhance the user's code. How EES produces better explanations is shown.

  9. Muon-Induced Neutrons Do Not Explain the DAMA Data

    NASA Astrophysics Data System (ADS)

    Klinger, J.; Kudryavtsev, V. A.

    2015-04-01

    We present an accurate model of the muon-induced background in the DAMA/LIBRA experiment. Our work challenges proposed mechanisms which seek to explain the observed DAMA signal modulation with muon-induced backgrounds. Muon generation and transport are performed using the MUSIC /MUSUN code, and subsequent interactions in the vicinity of the DAMA detector cavern are simulated with Geant4. We estimate the total muon-induced neutron flux in the detector cavern to be Φnν=1.0 ×10-9 cm-2 s-1 . We predict 3.49 ×10-5 counts /day /kg /keV , which accounts for less than 0.3% of the DAMA signal modulation amplitude.

  10. Trophic network models explain instability of Early Triassic terrestrial communities.

    PubMed

    Roopnarine, Peter D; Angielczyk, Kenneth D; Wang, Steve C; Hertog, Rachel

    2007-09-07

    Studies of the end-Permian mass extinction have emphasized potential abiotic causes and their direct biotic effects. Less attention has been devoted to secondary extinctions resulting from ecological crises and the effect of community structure on such extinctions. Here we use a trophic network model that combines topological and dynamic approaches to simulate disruptions of primary productivity in palaeocommunities. We apply the model to Permian and Triassic communities of the Karoo Basin, South Africa, and show that while Permian communities bear no evidence of being especially susceptible to extinction, Early Triassic communities appear to have been inherently less stable. Much of the instability results from the faster post-extinction diversification of amphibian guilds relative to amniotes. The resulting communities differed fundamentally in structure from their Permian predecessors. Additionally, our results imply that changing community structures over time may explain long-term trends like declining rates of Phanerozoic background extinction.

  11. [Francisco Varela's neurophenomenology of time: temporality of consciousness explained?].

    PubMed

    Vargas, Esteban; Canales-Johnson, Andrés; Claudio Fuentes, B

    2013-01-01

    This article attempts to clarify Francisco Varela's proposal of a neurophenomenology of time consciousness in the light of distinctions based on the philosophical literature of phenomenology and recent advances of neurobiology. The analysis is carried out considering three aspects. In the first of them, we discuss the phenomenological aspect of consciousness, accessible in first-person, which describes time as a structure with three inseparable moments (past-present-future) and three levels of temporality, and not merely as the chronometric time or clock time. In the second one, we analyze the neurobiological aspect of consciousness that tends to "explain" the phenomenological time in terms of three possible levels of neuronal integration. Thus, we propose a correspondence between the levels of phenomenological time and neural integration processes. Finally, we try to analyze this "correspondence" and the issues that follow from this by considering that the notion of time in this correspondence is, in essence, the clock time and not the phenomenological time consciousness.

  12. Environmental factors explaining the vegetation patterns in a temperate peatland.

    PubMed

    Pellerin, Stéphanie; Lagneau, Louis-Adrien; Lavoie, Martin; Larocque, Marie

    2009-08-01

    Although ombrotrophic temperate peatlands are important ecosystems for maintaining biodiversity in eastern North America, the environmental factors influencing their flora are only partly understood. The relationships between plant species distribution and environmental factors were thus studied within the oldest temperate peatland of Québec. Plant assemblages were identified by cluster analysis while CCA was used to related vegetation gradients to environmental factors. Five assemblages were identified; three typical of open bog and two characterized by more minerotrophic vegetation. Thicker peat deposit was encounter underlying the bog assemblages while higher water table level and percentage of free surface water distinguished the minerotrophic assemblages. Overall, the floristic patterns observed were spatially structured along the margins and the expanse. The most important environmental factors explaining this spatial gradient were the percentage of free surface water and the highest water-table level.

  13. Explaining How to Play Real-Time Strategy Games

    NASA Astrophysics Data System (ADS)

    Metoyer, Ronald; Stumpf, Simone; Neumann, Christoph; Dodge, Jonathan; Cao, Jill; Schnabel, Aaron

    Real-time strategy games share many aspects with real situations in domains such as battle planning, air traffic control, and emergency response team management which makes them appealing test-beds for Artificial Intelligence (AI) and machine learning. End user annotations could help to provide supplemental information for learning algorithms, especially when training data is sparse. This paper presents a formative study to uncover how experienced users explain game play in real-time strategy games. We report the results of our analysis of explanations and discuss their characteristics that could support the design of systems for use by experienced real-time strategy game users in specifying or annotating strategy-oriented behavior.

  14. Muon-Induced Neutrons Do Not Explain the DAMA Data.

    PubMed

    Klinger, J; Kudryavtsev, V A

    2015-04-17

    We present an accurate model of the muon-induced background in the DAMA/LIBRA experiment. Our work challenges proposed mechanisms which seek to explain the observed DAMA signal modulation with muon-induced backgrounds. Muon generation and transport are performed using the MUSIC/MUSUN code, and subsequent interactions in the vicinity of the DAMA detector cavern are simulated with Geant4. We estimate the total muon-induced neutron flux in the detector cavern to be Φ(n)(ν)=1.0 × 10(-9)  cm(-2) s(-1). We predict 3.49 × 10(-5)  counts/day/kg/keV, which accounts for less than 0.3% of the DAMA signal modulation amplitude.

  15. Carbonatite ring-complexes explained by caldera-style volcanism.

    PubMed

    Andersson, Magnus; Malehmir, Alireza; Troll, Valentin R; Dehghannejad, Mahdieh; Juhlin, Christopher; Ask, Maria

    2013-01-01

    Carbonatites are rare, carbonate-rich magmatic rocks that make up a minute portion of the crust only, yet they are of great relevance for our understanding of crustal and mantle processes. Although they occur in all continents and from Archaean to present, the deeper plumbing system of carbonatite ring-complexes is usually poorly constrained. Here, we show that carbonatite ring-complexes can be explained by caldera-style volcanism. Our geophysical investigation of the Alnö carbonatite ring-complex in central Sweden identifies a solidified saucer-shaped magma chamber at ~3 km depth that links to surface exposures through a ring fault system. Caldera subsidence during final stages of activity caused carbonatite eruptions north of the main complex, providing the crucial element to connect plutonic and eruptive features of carbonatite magmatism. The way carbonatite magmas are stored, transported and erupt at the surface is thus comparable to known emplacement styles from silicic calderas.

  16. Trophic network models explain instability of Early Triassic terrestrial communities

    PubMed Central

    Roopnarine, Peter D; Angielczyk, Kenneth D; Wang, Steve C; Hertog, Rachel

    2007-01-01

    Studies of the end-Permian mass extinction have emphasized potential abiotic causes and their direct biotic effects. Less attention has been devoted to secondary extinctions resulting from ecological crises and the effect of community structure on such extinctions. Here we use a trophic network model that combines topological and dynamic approaches to simulate disruptions of primary productivity in palaeocommunities. We apply the model to Permian and Triassic communities of the Karoo Basin, South Africa, and show that while Permian communities bear no evidence of being especially susceptible to extinction, Early Triassic communities appear to have been inherently less stable. Much of the instability results from the faster post-extinction diversification of amphibian guilds relative to amniotes. The resulting communities differed fundamentally in structure from their Permian predecessors. Additionally, our results imply that changing community structures over time may explain long-term trends like declining rates of Phanerozoic background extinction PMID:17609191

  17. Social inheritance can explain the structure of animal social networks.

    PubMed

    Ilany, Amiyaal; Akçay, Erol

    2016-06-28

    The social network structure of animal populations has major implications for survival, reproductive success, sexual selection and pathogen transmission of individuals. But as of yet, no general theory of social network structure exists that can explain the diversity of social networks observed in nature, and serve as a null model for detecting species and population-specific factors. Here we propose a simple and generally applicable model of social network structure. We consider the emergence of network structure as a result of social inheritance, in which newborns are likely to bond with maternal contacts, and via forming bonds randomly. We compare model output with data from several species, showing that it can generate networks with properties such as those observed in real social systems. Our model demonstrates that important observed properties of social networks, including heritability of network position or assortative associations, can be understood as consequences of social inheritance.

  18. Can Nomenclature for the Body be Explained by Embodiment Theories?

    PubMed

    Majid, Asifa; van Staden, Miriam

    2015-10-01

    According to widespread opinion, the meaning of body part terms is determined by salient discontinuities in the visual image; such that hands, feet, arms, and legs, are natural parts. If so, one would expect these parts to have distinct names which correspond in meaning across languages. To test this proposal, we compared three unrelated languages-Dutch, Japanese, and Indonesian-and found both naming systems and boundaries of even basic body part terms display variation across languages. Bottom-up cues alone cannot explain natural language semantic systems; there simply is not a one-to-one mapping of the body semantic system to the body structural description. Although body parts are flexibly construed across languages, body parts semantics are, nevertheless, constrained by non-linguistic representations in the body structural description, suggesting these are necessary, although not sufficient, in accounting for aspects of the body lexicon.

  19. [To explain is to narrate. How to visualize scientific data].

    PubMed

    Hawtin, Nigel

    2014-01-01

    When you try to appeal a vast ranging audience, as it occurs at the New Scientist that addresses scientists as well as the general public, your scientific visual explainer must be succinct, clear, accurate and easily understandable. In order to reach this goal, your message should provide only the main data, the ones that allow you to balance information and clarity: information should be put into context and all the extra details should be cut down. It is very important, then, to know well both your audience and the subject you are going to describe, as graphic masters of the past, like William Playfair and Charles Minard, have taught us. Moreover, you should try to engage your reader connecting the storytelling power of words and the driving force of the graphics: colours, visual elements, typography. To be effective, in fact, an infographic should not only be truthful and functional, but also elegant, having style and legibility.

  20. Explaining sexual harassment judgments: looking beyond gender of the rater.

    PubMed

    O'Connor, Maureen; Gutek, Barbara A; Stockdale, Margaret; Geer, Tracey M; Melançon, Renée

    2004-02-01

    In two decades of research on sexual harassment, one finding that appears repeatedly is that gender of the rater influences judgments about sexual harassment such that women are more likely than men to label behavior as sexual harassment. Yet, sexual harassment judgments are complex, particularly in situations that culminate in legal proceedings. And, this one variable, gender, may have been overemphasized to the exclusion of other situational and rater characteristic variables. Moreover, why do gender differences appear? As work by Wiener and his colleagues have done (R. L. Wiener et al., 2002; R. L. Wiener & L. Hurt, 2000; R. L. Wiener, L. Hurt, B. Russell, K. Mannen, & C. Gasper, 1997), this study attempts to look beyond gender to answer this question. In the studies reported here, raters (undergraduates and community adults), either read a written scenario or viewed a videotaped reenactment of a sexual harassment trial. The nature of the work environment was manipulated to see what, if any, effect the context would have on gender effects. Additionally, a number of rater characteristics beyond gender were measured, including ambivalent sexism attitudes of the raters, their judgments of complainant credibility, and self-referencing that might help explain rater judgments. Respondent gender, work environment, and community vs. student sample differences produced reliable differences in sexual harassment ratings in both the written and video trial versions of the study. The gender and sample differences in the sexual harassment ratings, however, are explained by a model which incorporates hostile sexism, perceptions of the complainants credibility, and raters' own ability to put themselves in the complainant's position (self-referencing).

  1. Why Cosmic Fine-Tuning Needs to BE Explained

    NASA Astrophysics Data System (ADS)

    Manson, Neil Alan

    Discoveries in modern physics and Big Bang cosmology indicate that if either the initial conditions of the universe or the physical laws governing its development had differed even slightly, life could never have developed. It is for this reason that the universe is said to be ``fine-tuned'' for life. I argue that cosmic fine-tuning, which some want to dismiss as the way things just happen to be, in fact needs to be explained. In Chapter One I provide an overview of the evidence that the universe is fine-tuned for life. In Chapter Two I present a set of sufficient conditions for a fact's needing to be explained. The conditions are that the fact is improbable and that a ``tidy'' explanation of it is available. A tidy explanation of a fact is considerably less improbable than that fact and makes the obtaining of that fact considerably less improbable. Chapters Three, Four, and Five are devoted to showing that cosmic Chapter Three I argue that the universe's being finely tuned for life can meaningfully be considered improbable. In Chapter Four I claim that there is at least one tidy explanation of cosmic fine-tuning: that the universe was created by some sort of extramundane designer. In Chapters Four and Five I respond to three objections. The first is that the design hypothesis is ad hoc. The second is that we have no reason to believe a supernatural designer would prefer life-permitting cosmoi to other possible cosmoi and that our tendency to believe otherwise is the result of anthropocentrism. The third is that the design hypothesis never buys us an explanatory advantage.

  2. A theory with consolidation: Linking everything to explain everything

    NASA Astrophysics Data System (ADS)

    Biraris, Gaurav Shantaram

    The paper reports a theory which gives explicit (ontic) understanding of the abstract (epistemic) mechanisms spanning many branches of physics. It results to most modern physics starting from Newtonian physics by abandoning progress in twentieth century. The theory assumes consolidation of points in 4-balls of specific radius in the universe. Thus the 4-balls are fundamental elements of the universe. Analogue of momentum defined as soul vector is assumed to be induced on the 4-balls at the beginning of the universe. Then with progression of local time, collisions happen leading to different rotations of CNs. For such rotations, the consolidation provides centripetal binding. By using general terminologies of force and work, the mass energy mechanism gets revealed. The theory provides explicit interpretation of intrinsic properties of mass, electric charge, color charge, weak charge, spin etc. It also provides explicit understanding of the wave-particle duality & quantum mechanics. Epistemic study of the universe with the consolidation results to conventional quantum theories. Elementary mechanism of the field interactions is evident due to conservation of the soul vectors, and its epistemic expectation results to the gauge theories. The theory predicts that four types of interaction would exist in the universe along with the acceptable relative strengths; it provides fundamental interpretation of the physical forces. Further, it explains the basic mechanisms which can be identified with dark energy & dark matter. It also results to (or explains) entanglement, chirality, excess of matter, 4-component spinor, real-abstract (ontic-epistemic) correspondence etc. The theory is beyond standard model and results to the standard model, relativity, dark energy & dark matter, starting by simple assumptions.

  3. Social Processes Explaining the Benefits of Al-Anon Participation

    PubMed Central

    Timko, Christine; Halvorson, Max; Kong, Calvin; Moos, Rudolf H

    2015-01-01

    This study examined social processes of support, goal direction, provision of role models, and involvement in rewarding activities to explain benefits of participating in Al-Anon, a 12-step mutual-help program for people concerned about another person’s substance use. Newcomers to Al-Anon were studied at baseline and 6 months later, when they were identified as having sustained attendance or dropped out. Among newcomers, and among established Al-Anon members (“oldtimers”), we also used number of Al-Anon meetings attended during follow-up to indicate extent of participation. Social processes significantly mediated between newcomers’ attendance status as sustained (versus dropped out) and outcomes of Al-Anon in the domains of life context (e.g., better quality of life, better able to handle problems due to the drinker), improved positive symptoms (more self-esteem, more hopeful), and decreased negative symptoms (e.g., less abuse, less depressed). Social processes also significantly mediated between newcomers’ number of meetings and outcomes. However, among oldtimers, Al-Anon attendance was not associated with outcomes, so the potential mediating role of social processes could not be examined, but social processes were associated with outcomes. Findings add to the growing body of work identifying mechanisms by which 12-step groups are effective, by showing that bonding, goal direction, and access to peers in recovery and rewarding pursuits help to explain associations between sustained Al-Anon participation among newcomers and improvements on key concerns of Al-Anon attendees. Al-Anon is free of charge and widely available, making it a potentially cost-effective public health resource in helping to alleviate negative consequences of concern about another’s addiction. PMID:26727006

  4. Color constancy in natural scenes explained by global image statistics.

    PubMed

    Foster, David H; Amano, Kinjiro; Nascimento, Sérgio M C

    2006-01-01

    To what extent do observers' judgments of surface color with natural scenes depend on global image statistics? To address this question, a psychophysical experiment was performed in which images of natural scenes under two successive daylights were presented on a computer-controlled high-resolution color monitor. Observers reported whether there was a change in reflectance of a test surface in the scene. The scenes were obtained with a hyperspectral imaging system and included variously trees, shrubs, grasses, ferns, flowers, rocks, and buildings. Discrimination performance, quantified on a scale of 0 to 1 with a color-constancy index, varied from 0.69 to 0.97 over 21 scenes and two illuminant changes, from a correlated color temperature of 25,000 K to 6700 K and from 4000 K to 6700 K. The best account of these effects was provided by receptor-based rather than colorimetric properties of the images. Thus, in a linear regression, 43% of the variance in constancy index was explained by the log of the mean relative deviation in spatial cone-excitation ratios evaluated globally across the two images of a scene. A further 20% was explained by including the mean chroma of the first image and its difference from that of the second image and a further 7% by the mean difference in hue. Together, all four global color properties accounted for 70% of the variance and provided a good fit to the effects of scene and of illuminant change on color constancy, and, additionally, of changing test-surface position. By contrast, a spatial-frequency analysis of the images showed that the gradient of the luminance amplitude spectrum accounted for only 5% of the variance.

  5. How to mechanistically explain the CONDOR study data.

    PubMed

    Spies, C M; Stemmler, E; Buttgereit, F

    2015-01-01

    Results of the CONDOR study suggest that in osteoarthritis and rheumatoid arthritis patients at elevated risk of gastrointestinal (GI) events, treatment with celecoxib, a cyclooxygenase (COX)-2 selective non-steroidal anti-inflammatory drug (NSAID), demonstrated significantly lower toxicity in the upper and lower (GI) tract when compared to the non-selective NSAID diclofenac plus a proton-pump-inhibitor (PPI), omeprazole. According to current knowledge, traditional NSAIDs (tNSAIDs) as non-selective COX-inhibitors exert their damaging effects on the upper GI tract, largely by reduction of the COX-1 related synthesis of gastro-protective prostaglandins. Thus, the question arises, how NSAIDs do exert their damaging effects especially in the lower GI tract and how to explain the reduced risk of a COX-2 selective inhibitor, celecoxib. Here we hypothesize, that the toxicity of celecoxib on enteral mucosa cells is lower than observed with other NSAIDs, and can be explained COX-independently by typical physicochemical properties of the NSAID substances (e.g., acidic, lipophilic, amphiphilic, surfactant properties). As a consequence these features account for differences in (1) uncoupling effects on mitochondria, (2) effects on cell membrane integrity, and/or (3) formation of "toxic micelles" with bile salts. The evidence for these differences is mainly based on experimental findings. However, several phenomena show differences in extent (e.g., uncoupling effects). The reduced toxicity appears to be rather a substance-specific characteristic. This is an unconditional reason to carry on investigating these phenomena in experimental and large-scale clinical trials.

  6. Explaining socio-economic inequalities in immunization coverage in Nigeria.

    PubMed

    Ataguba, John E; Ojo, Kenneth O; Ichoku, Hyacinth E

    2016-11-01

    Globally, in 2013 over 6 million children younger than 5 years died from either an infectious cause or during the neonatal period. A large proportion of these deaths occurred in developing countries, especially in sub-Saharan Africa. Immunization is one way to reduce childhood morbidity and deaths. In Nigeria, however, although immunization is provided without a charge at public facilities, coverage remains low and deaths from vaccine preventable diseases are high. This article seeks to assess inequalities in full and partial immunization coverage in Nigeria. It also assesses inequality in the 'intensity' of immunization coverage and it explains the factors that account for disparities in child immunization coverage in the country. Using nationally representative data, this article shows that disparities exist in the coverage of immunization to the advantage of the rich. Also, factors such as mother's literacy, region and location of the child, and socio-economic status explain the disparities in immunization coverage in Nigeria. Apart from addressing these issues, the article notes the importance of addressing other social determinants of health to reduce the disparities in immunization coverage in the country. These should be in line with the social values of communities so as to ensure acceptability and compliance. We argue that any policy that addresses these issues will likely reduce disparities in immunization coverage and put Nigeria on the road to sustainable development. © The Author 2016. Published by Oxford University Press in association with The London School of Hygiene and Tropical Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  7. Social processes explaining the benefits of Al-Anon participation.

    PubMed

    Timko, Christine; Halvorson, Max; Kong, Calvin; Moos, Rudolf H

    2015-12-01

    This study examined social processes of support, goal direction, provision of role models, and involvement in rewarding activities to explain benefits of participating in Al-Anon, a 12-step mutual-help program for people concerned about another person's substance use. Newcomers to Al-Anon were studied at baseline and 6 months later, at which time they were identified as having either sustained attendance or dropped out. Among both newcomers and established Al-Anon members ("old-timers"), we also used number of Al-Anon meetings attended during follow-up to indicate extent of participation. Social processes significantly mediated newcomers' sustained attendance status versus dropped out and outcomes of Al-Anon in the areas of life context (e.g., better quality of life, better able to handle problems due to the drinker), improved positive symptoms (e.g., higher self-esteem, more hopeful), and decreased negative symptoms (e.g., less abuse, less depressed). Social processes also significantly mediated newcomers' number of meetings attended and outcomes. However, among old-timers, Al-Anon attendance was not associated with outcomes, so the potential mediating role of social processes could not be examined, but social processes were associated with outcomes. Findings add to the growing body of work identifying mechanisms by which 12-step groups are effective, by showing that bonding, goal direction, and access to peers in recovery and rewarding pursuits help to explain associations between sustained Al-Anon participation among newcomers and improvements on key concerns of Al-Anon attendees. Al-Anon is free of charge and widely available, making it a potentially cost-effective public health resource for help alleviating negative consequences of concern about another's addiction.

  8. Strange history: the fall of Rome explained in Hereditas.

    PubMed

    Bengtsson, Bengt O

    2014-12-01

    In 1921 Hereditas published an article on the fall of Rome written by the famous classical scholar Martin P:son Nilsson. Why was a paper on this unexpected topic printed in the newly founded journal? To Nilsson, the demise of the Roman Empire was explained by the "bastardization" occurring between "races" from different parts of the realm. Offspring from mixed couples were of a less stable "type" than their parents, due to the breaking up by recombination of the original hereditary dispositions, which led to a general loss of competence to rule and govern. Thus, the "hardness" of human genes, together with their recombination, was - according to Nilsson - the main cause of the fall of Rome. Nilsson's argument is not particularly convincingly presented. Human "races" are taken to have the same genetic structure as inbred crop strains, and Nilsson believes in a metaphysical unity between the individual and the race to which it belongs. However, in my view, Martin P:son Nilsson and his friend Herman Nilsson-Ehle had wider aims with the article than to explain a historical event. The article can be read as indicating strong support from the classical human sciences to the ambitious new science of genetics. Support is also transferred from genetics to the conservative worldview, where the immutability and inflexibility of the Mendelian genes are used to strengthen the wish for greater stability in politics and life. The strange article in Hereditas can, thus, be read as an early instance in the - still ongoing - tug-of-war between the conservative and the liberal ideological poles over how genetic results best are socially interpreted.

  9. Classic reaction kinetics can explain complex patterns of antibiotic action

    PubMed Central

    zur Wiesch, P. Abel; Abel, S.; Gkotzis, S.; Ocampo, P.; Engelstädter, J.; Hinkley, T.; Magnus, C.; Waldor, M. K.; Udekwu, K.; Cohen, T.

    2015-01-01

    Finding optimal dosing strategies for treating bacterial infections is extremely difficult, and improving therapy requires costly and time-intensive experiments. To date, an incomplete mechanistic understanding of drug effects has limited our ability to make accurate quantitative predictions of drug-mediated bacterial killing and impeded the rational design of antibiotic treatment strategies. Three poorly understood phenomena complicate predictions of antibiotic activity: post-antibiotic growth suppression, density-dependent antibiotic effects, and persister cell formation. Here, we show that chemical binding kinetics alone are sufficient to explain these three phenomena, using single cell data and time-kill curves of Escherichia coli and Vibrio cholerae exposed to a variety of antibiotics in combination with a theoretical model that links chemical reaction kinetics to bacterial population biology. Our model reproduces existing observations, has a high predictive power across different experimental setups (R2= 0.86), and makes several testable predictions, which we verified in new experiments and by analysing published data from a clinical trial on tuberculosis therapy. While a variety of biological mechanisms have previously been invoked to explain post-antibiotic growth suppression, density-dependent antibiotic effects, and especially persister cell formation, our findings reveal that a simple model which considers only binding kinetics provides a parsimonious and unifying explanation for these three complex, phenotypically distinct behaviours. Current antibiotic and other chemotherapeutic regimens are often based on trial-and-error or expert opinion. Our ‘chemical reaction kinetics’-based approach may inform new strategies, that are based on rational design. PMID:25972005

  10. Can neighborhoods explain racial/ethnic differences in adolescent inactivity?

    PubMed

    Richmond, Tracy K; Field, Alison E; Rich, Michael

    2007-01-01

    To determine if neighborhoods and their attributes contribute to racial/ethnic disparities in adolescent inactivity. We undertook a cross-sectional analysis of the National Longitudinal Study of Adolescent Health (n = 17,007), a nationally representative school-based study in the United States. Stratifying by gender, we used multivariate linear regression and multi-level modeling to determine whether neighborhood of residence may partially explain racial/ethnic disparities in adolescent physical inactivity, defined as hours viewing television or videos/DVDs and/or playing computer/video games each week. Participants lived in largely segregated communities. Black and Hispanic adolescent girls reported higher levels of inactivity than White adolescent girls (21 vs. 15 vs. 13 hours/week, respectively, p <0.001). Similar patterns were seen in adolescent boys, with Black adolescent males reporting a mean of 26 hours/week; Hispanic boys a mean of 20 hours/week; and White boys a mean of 17 hours/week of inactivity (p <0.001). After accounting for between-neighborhood variation, there were no residual within-neighborhood differences in inactivity between Hispanic and White adolescent girls (gamma = -0.06, p =0.93); when living in the same neighborhood Hispanic and White girls had similar levels of inactivity. Black adolescent girls and boys were found to have higher levels of inactivity no matter where they lived (gamma =7.00, p <0.001 for girls; gamma = 6.96, p <0.001 for boys). Hispanic boys had similar patterns of inactivity to White boys (gamma =-1.57, p = 0.12). In both males and females, the reported rate of violent crime in the neighborhood was associated with inactivity, despite the individual's perception of his/her neighborhood as safe not being predictive. Although inactivity varies by race/ethnicity and gender, only in Hispanic adolescent girls does neighborhood fully explain the differential use. Our findings suggest that approaches other than changing

  11. CRISPR adaptation biases explain preference for acquisition of foreign DNA.

    PubMed

    Levy, Asaf; Goren, Moran G; Yosef, Ido; Auster, Oren; Manor, Miriam; Amitai, Gil; Edgar, Rotem; Qimron, Udi; Sorek, Rotem

    2015-04-23

    CRISPR-Cas (clustered, regularly interspaced short palindromic repeats coupled with CRISPR-associated proteins) is a bacterial immunity system that protects against invading phages or plasmids. In the process of CRISPR adaptation, short pieces of DNA ('spacers') are acquired from foreign elements and integrated into the CRISPR array. So far, it has remained a mystery how spacers are preferentially acquired from the foreign DNA while the self chromosome is avoided. Here we show that spacer acquisition is replication-dependent, and that DNA breaks formed at stalled replication forks promote spacer acquisition. Chromosomal hotspots of spacer acquisition were confined by Chi sites, which are sequence octamers highly enriched on the bacterial chromosome, suggesting that these sites limit spacer acquisition from self DNA. We further show that the avoidance of self is mediated by the RecBCD double-stranded DNA break repair complex. Our results suggest that, in Escherichia coli, acquisition of new spacers largely depends on RecBCD-mediated processing of double-stranded DNA breaks occurring primarily at replication forks, and that the preference for foreign DNA is achieved through the higher density of Chi sites on the self chromosome, in combination with the higher number of forks on the foreign DNA. This model explains the strong preference to acquire spacers both from high copy plasmids and from phages.

  12. Buzz Factor or Innovation Potential: What Explains Cryptocurrencies’ Returns?

    PubMed Central

    Wang, Sha

    2017-01-01

    Cryptocurrencies have become increasingly popular since the introduction of bitcoin in 2009. In this paper, we identify factors associated with variations in cryptocurrencies’ market values. In the past, researchers argued that the “buzz” surrounding cryptocurrencies in online media explained their price variations. But this observation obfuscates the notion that cryptocurrencies, unlike fiat currencies, are technologies entailing a true innovation potential. By using, for the first time, a unique measure of innovation potential, we find that the latter is in fact the most important factor associated with increases in cryptocurrency returns. By contrast, we find that the buzz surrounding cryptocurrencies is negatively associated with returns after controlling for a variety of factors, such as supply growth and liquidity. Also interesting is our finding that a cryptocurrency’s association with fraudulent activity is not negatively associated with weekly returns—a result that further qualifies the media’s influence on cryptocurrencies. Finally, we find that an increase in supply is positively associated with weekly returns. Taken together, our findings show that cryptocurrencies do not behave like traditional currencies or commodities—unlike what most prior research has assumed—and depict an industry that is much more mature, and much less speculative, than has been implied by previous accounts. PMID:28085906

  13. Metacommunity theory explains the emergence of food web complexity.

    PubMed

    Pillai, Pradeep; Gonzalez, Andrew; Loreau, Michel

    2011-11-29

    Food webs are highly complex ecological networks, dynamic in both space and time. Metacommunity models are now at the core of unified theories of biodiversity, but to date they have not addressed food web complexity. Here we show that metacommunity theory can explain the emergence of species-rich food webs with complex network topologies. Our analysis shows that network branching in the food web is maximized at intermediate colonization rates and limited dispersal scales, which also leads to concomitant peaks in species diversity. Increased food web complexity and species diversity are made possible by the structural role played by network branches that are supported by omnivore and generalist feeding links. Thus, in contrast to traditional food web theory, which emphasizes the destabilizing effect of omnivory feeding in closed systems, metacommunity theory predicts that these feeding links, which are commonly observed in empirical food webs, play a critical structural role as food webs assemble in space. As this mechanism functions at the metacommunity level, evidence for its operation in nature will be obtained through multiscale surveys of food web structure. Finally, we apply our theory to reveal the effects of habitat destruction on network complexity and metacommunity diversity.

  14. Explaining the distribution of breeding and dispersal syndromes in conifers.

    PubMed

    Leslie, Andrew B; Beaulieu, Jeremy M; Crane, Peter R; Donoghue, Michael J

    2013-11-07

    The evolution of plants exhibiting different sexes, or dioecy, is correlated with a number of ecological and life-history traits such as woody growth form and animal-dispersed seeds, but the underlying causes of these associations are unclear. Previous work in seed plants has suggested that the evolution of fleshy cones or seeds may favour dioecy. In this study, we use a well-sampled molecular phylogeny of conifers to show that although dioecy and fleshiness strongly co-occur at the species level, this relationship has not resulted from numerous separate origins of this trait combination or from differential rates of diversification. Instead, we suggest that two character combinations-the ancestral dry-monoecious condition and the derived fleshy-dioecious condition-have persisted in conifers longer than other combinations over evolutionary time. The persistence of these trait combinations appears to reflect differences in the rate of successful transition into and out of these character states over time, as well as the geographical restriction of species with rare combinations and their consequent vulnerability to extinction. In general, we argue that such persistence explanations should be considered alongside 'key innovation' hypotheses in explaining the phylogenetic distribution of traits.

  15. Explaining the distribution of breeding and dispersal syndromes in conifers

    PubMed Central

    Leslie, Andrew B.; Beaulieu, Jeremy M.; Crane, Peter R.; Donoghue, Michael J.

    2013-01-01

    The evolution of plants exhibiting different sexes, or dioecy, is correlated with a number of ecological and life-history traits such as woody growth form and animal-dispersed seeds, but the underlying causes of these associations are unclear. Previous work in seed plants has suggested that the evolution of fleshy cones or seeds may favour dioecy. In this study, we use a well-sampled molecular phylogeny of conifers to show that although dioecy and fleshiness strongly co-occur at the species level, this relationship has not resulted from numerous separate origins of this trait combination or from differential rates of diversification. Instead, we suggest that two character combinations—the ancestral dry-monoecious condition and the derived fleshy-dioecious condition—have persisted in conifers longer than other combinations over evolutionary time. The persistence of these trait combinations appears to reflect differences in the rate of successful transition into and out of these character states over time, as well as the geographical restriction of species with rare combinations and their consequent vulnerability to extinction. In general, we argue that such persistence explanations should be considered alongside ‘key innovation’ hypotheses in explaining the phylogenetic distribution of traits. PMID:24026822

  16. Explaining employment relationships with social exchange and job embeddedness.

    PubMed

    Hom, Peter W; Tsui, Anne S; Wu, Joshua B; Lee, Thomas W; Zhang, Ann Yan; Fu, Ping Ping; Li, Lan

    2009-03-01

    The research reported in this article clarifies how employee-organization relationships (EORs) work. Specifically, the authors tested whether social exchange and job embeddedness mediate how mutual-investment (whereby employers offer high inducements to employees for their high contributions) and over-investment (high inducements without corresponding high expected contributions) EOR approaches, which are based on Tsui, Pearce, Porter, and Tripoli's (1997) framework, affect quit propensity and organizational commitment. Two studies evaluated these intervening mechanisms. Study 1 surveyed 953 Chinese managers attending part-time master of business administration (MBA) programs in China, whereas Study 2 collected cross-sectional and longitudinal data from 526 Chinese middle managers in 41 firms. Standard and multilevel causal modeling techniques affirmed that social exchange and job embeddedness translate EOR influence. A second multilevel test using lagged outcome measures further established that job embeddedness mediates long-term EOR effects over 18 months. These findings corroborate prevailing views that social exchange explains how mutual- and over-investment EORs motivate greater workforce commitment and loyalty. This study enriches EOR perspectives by identifying job embeddedness as another mediator that is more enduring than social exchange. (c) 2009 APA, all rights reserved.

  17. Relative resource abundance explains butterfly biodiversity in island communities.

    PubMed

    Yamamoto, Naoaki; Yokoyama, Jun; Kawata, Masakado

    2007-06-19

    Ecologists have long been intrigued by the factors that control the pattern of biodiversity, i.e., the distribution and abundance of species. Previous studies have demonstrated that coexisting species partition their resources and/or that the compositional similarity between communities is determined by environmental factors, lending support to the niche-assembly model. However, no attempt has been made to test whether the relative amount of resources that reflects relative niche space controls relative species abundance in communities. Here, we demonstrate that the relative abundance of butterfly species in island communities is significantly related to the relative biomasses of their host plants but not to the geographic distance between communities. In the studied communities, the biomass of particular host plant species positively affected the abundance of the butterfly species that used them, and consequently, influenced the relative abundance of the butterfly communities. This indicated that the niche space of butterflies (i.e., the amount of resources) strongly influences butterfly biodiversity patterns. We present this field evidence of the niche-apportionment model that propose that the relative amount of niche space explains the pattern of the relative abundance of the species in communities.

  18. Cortical thinning explains changes in sleep slow waves during adulthood.

    PubMed

    Dubé, Jonathan; Lafortune, Marjolaine; Bedetti, Christophe; Bouchard, Maude; Gagnon, Jean François; Doyon, Julien; Evans, Alan C; Lina, Jean-Marc; Carrier, Julie

    2015-05-20

    Sleep slow waves (SWs) change considerably throughout normal aging. In humans, SWs are generated and propagate on a structural backbone of highly interconnected cortical regions that form most of the default mode network, such as the insula, cingulate cortices, temporal lobe, parietal lobe, and medial frontal lobe. Regions in this network undergo cortical thinning and breakdown in structural and functional connectivity over the course of normal aging. In this study, we investigated how changes in cortical thickness (CT), a measure of gray matter integrity, are involved in modifications of sleep SWs during adulthood in humans. Thirty young (mean age = 23.49 years; SD = 2.79) and 33 older (mean age = 60.35 years; SD = 5.71) healthy subjects underwent a nocturnal polysomnography and T1 MRI. We show that, when controlling for age, higher SW density (nb/min of nonrapid eye movement sleep) was associated with higher CT in cortical regions involved in SW generation surrounding the lateral fissure (insula, superior temporal, parietal, middle frontal), whereas higher SW amplitude was associated with higher CT in middle frontal, medial prefrontal, and medial posterior regions. Mediation analyses demonstrated that thinning in a network of cortical regions involved in SW generation and propagation, but also in cognitive functions, explained the age-related decrease in SW density and amplitude. Altogether, our results suggest that microstructural degradation of specific cortical regions compromise SW generation and propagation in older subjects, critically contributing to age-related changes in SW oscillations.

  19. Nonlinear Bayesian cue integration explains the dynamics of vocal learning

    NASA Astrophysics Data System (ADS)

    Zhou, Baohua; Sober, Samuel; Nemenman, Ilya

    The acoustics of vocal production in songbirds is tightly regulated during both development and adulthood as birds progressively refine their song using sensory feedback to match an acoustic target. Here, we perturb this sensory feedback using headphones to shift the pitch (fundamental frequency) of song. When the pitch is shifted upwards (downwards), birds eventually learn to compensate and sing lower (higher), bringing the experienced pitch closer to the target. Paradoxically, the speed and amplitude of this motor learning decrease with increases in the introduced error size, so that birds respond rapidly to a small sensory perturbation, while seemingly never correcting a much bigger one. Similar results are observed broadly across the animal kingdom, and they do not derive from a limited plasticity of the adult brain since birds can compensate for a large error as long as the error is imposed gradually. We develop a mathematical model based on nonlinear Bayesian integration of two sensory modalities (one perturbed and the other not) that quantitatively explains all of these observations. The model makes predictions about the structure of the probability distribution of the pitches sung by birds during the pitch shift experiments, which we confirm using experimental data. This work was supported in part by James S. McDonnell Foundation Grant # 220020321, NSF Grant # IOS/1208126, NSF Grant # IOS/1456912 and NIH Grants # R01NS084844.

  20. Can mathematics explain the evolution of human language?

    PubMed

    Witzany, Guenther

    2011-09-01

    Investigation into the sequence structure of the genetic code by means of an informatic approach is a real success story. The features of human language are also the object of investigation within the realm of formal language theories. They focus on the common rules of a universal grammar that lies behind all languages and determine generation of syntactic structures. This universal grammar is a depiction of material reality, i.e., the hidden logical order of things and its relations determined by natural laws. Therefore mathematics is viewed not only as an appropriate tool to investigate human language and genetic code structures through computer science-based formal language theory but is itself a depiction of material reality. This confusion between language as a scientific tool to describe observations/experiences within cognitive constructed models and formal language as a direct depiction of material reality occurs not only in current approaches but was the central focus of the philosophy of science debate in the twentieth century, with rather unexpected results. This article recalls these results and their implications for more recent mathematical approaches that also attempt to explain the evolution of human language.

  1. Explaining History. Hippolyte Taine's Philosophy of Historical Science

    NASA Astrophysics Data System (ADS)

    Müller, Philipp

    Historians of European historiography have often characterized Hippolyte Taine (1828-1893) as an adherent of the positivist school of thought, typical for the development of a scientific culture in Western Europe that differed from its German counterpart.1 In accordance with that view, Wilhelm Dilthey grouped him together with other scholars like John Stuart Mill and Herbert Spencer against who Dilthey tried to develop his conception of the human sciences based on the notion of "verstehen" (see Dilthey [1924] 1957, 139ff.). Dilthey understood Taine as proposing to analyze the human mind by identifying its individual components and then explaining their meaning by laws of their relation. He argued that such an approach might be adequate for the natural sciences, but neglected the fact that an analysis of the mind had to start from a given psychological connection that was prior to any definition of particular phenomena. From Dilthey's point of view, applying Taine's theory to historical studies only made them look more objective while actually Taine was unaware of just following the prevailing convictions of his time (idem, 191f.).

  2. Explaining Multi-wavelength Photometric Variability in Young Stellar Objects

    NASA Astrophysics Data System (ADS)

    Kesseli, Aurora; Whitney, B.; Wood, K.; Plavchan, P.; Terebey, S.; Stauffer, J. R.; Morales-Calderon, M.; YSOVAR

    2013-01-01

    We explore a variety of radiation transfer models to explain multi-wavelength photometric variability of young stellar objects in the Orion Nebula Cluster (Morales-Calderon et al. (2011). Our models include hotspots, warps in the accretion disk, and spiral arms. Variability comes in different types, which have been categorized as periodic or quasi-periodic, narrow or broad dips in the light curves, and rapid flux variations or “wild type” stars. Our models can successfully reproduce these. The optical and near-infrared light curves are sensitive to the stellar variations and obscurations from the circumstellar material. The mid-infrared provides an additional diagnostic because it is sensitive to emission from the inner disk and the inner wall height. Our models make specific predictions as to the shapes and phasing of optical through mid-infrared photometry that can be tested with multi-wavelength time-series data. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech and was partially supported by the National Science Foundation's REU program through NSF Award AST-1004881.

  3. What is believed is what is explained (sometimes)

    SciTech Connect

    Li, Renwei; Pereira, L.M.

    1996-12-31

    This paper presents a formal and computational methodology for incorporation of new knowledge into knowledge bases about actions and changes. We employ Gelfond and Lifschitz action description language A to describe domains of actions. The knowledge bases on domains of actions are defined and obtained by a new translation from domain descriptions in A into abductive normal logic programs, where a time dimension is incorporated. The knowledge bases are shown to be both sound and complete with respect to their domain descriptions. In particular, we propose a possible causes approach (PCA) to belief update based on the slogan: What is believed is what is explained. A possible cause of new knowledge consists of abduced occurrences of actions and value propositions about the initial state of the domain of actions, that would allow to derive the new knowledge. We show how to compute possible causes with abductive logic programming, and present some techniques to improve search efficiency. We use examples to compare our possible causes approach with Ginsberg`s possible worlds approach (PWA) and Winslett`s possible models approach (PMA).

  4. Surprisingly rational: probability theory plus noise explains biases in judgment.

    PubMed

    Costello, Fintan; Watts, Paul

    2014-07-01

    The systematic biases seen in people's probability judgments are typically taken as evidence that people do not use the rules of probability theory when reasoning about probability but instead use heuristics, which sometimes yield reasonable judgments and sometimes yield systematic biases. This view has had a major impact in economics, law, medicine, and other fields; indeed, the idea that people cannot reason with probabilities has become a truism. We present a simple alternative to this view, where people reason about probability according to probability theory but are subject to random variation or noise in the reasoning process. In this account the effect of noise is canceled for some probabilistic expressions. Analyzing data from 2 experiments, we find that, for these expressions, people's probability judgments are strikingly close to those required by probability theory. For other expressions, this account produces systematic deviations in probability estimates. These deviations explain 4 reliable biases in human probabilistic reasoning (conservatism, subadditivity, conjunction, and disjunction fallacies). These results suggest that people's probability judgments embody the rules of probability theory and that biases in those judgments are due to the effects of random noise.

  5. Optimization of biomass composition explains microbial growth-stoichiometry relationships

    USGS Publications Warehouse

    Franklin, O.; Hall, E.K.; Kaiser, C.; Battin, T.J.; Richter, A.

    2011-01-01

    Integrating microbial physiology and biomass stoichiometry opens far-reaching possibilities for linking microbial dynamics to ecosystem processes. For example, the growth-rate hypothesis (GRH) predicts positive correlations among growth rate, RNA content, and biomass phosphorus (P) content. Such relationships have been used to infer patterns of microbial activity, resource availability, and nutrient recycling in ecosystems. However, for microorganisms it is unclear under which resource conditions the GRH applies. We developed a model to test whether the response of microbial biomass stoichiometry to variable resource stoichiometry can be explained by a trade-off among cellular components that maximizes growth. The results show mechanistically why the GRH is valid under P limitation but not under N limitation. We also show why variability of growth rate-biomass stoichiometry relationships is lower under P limitation than under N or C limitation. These theoretical results are supported by experimental data on macromolecular composition (RNA, DNA, and protein) and biomass stoichiometry from two different bacteria. In addition, compared to a model with strictly homeostatic biomass, the optimization mechanism we suggest results in increased microbial N and P mineralization during organic-matter decomposition. Therefore, this mechanism may also have important implications for our understanding of nutrient cycling in ecosystems.

  6. Can mathematics explain the evolution of human language?

    PubMed Central

    2011-01-01

    Investigation into the sequence structure of the genetic code by means of an informatic approach is a real success story. The features of human language are also the object of investigation within the realm of formal language theories. They focus on the common rules of a universal grammar that lies behind all languages and determine generation of syntactic structures. This universal grammar is a depiction of material reality, i.e., the hidden logical order of things and its relations determined by natural laws. Therefore mathematics is viewed not only as an appropriate tool to investigate human language and genetic code structures through computer science-based formal language theory but is itself a depiction of material reality. This confusion between language as a scientific tool to describe observations/experiences within cognitive constructed models and formal language as a direct depiction of material reality occurs not only in current approaches but was the central focus of the philosophy of science debate in the twentieth century, with rather unexpected results. This article recalls these results and their implications for more recent mathematical approaches that also attempt to explain the evolution of human language. PMID:22046452

  7. Type-IV Pilus Deformation Can Explain Retraction Behavior

    PubMed Central

    Ghosh, Ranajay; Kumar, Aloke; Vaziri, Ashkan

    2014-01-01

    Polymeric filament like type IV Pilus (TFP) can transfer forces in excess of 100 pN during their retraction before stalling, powering surface translocation(twitching). Single TFP level experiments have shown remarkable nonlinearity in the retraction behavior influenced by the external load as well as levels of PilT molecular motor protein. This includes reversal of motion near stall forces when the concentration of the PilT protein is loweblack significantly. In order to explain this behavior, we analyze the coupling of TFP elasticity and interfacial behavior with PilT kinetics. We model retraction as reaction controlled and elongation as transport controlled process. The reaction rates vary with TFP deformation which is modeled as a compound elastic body consisting of multiple helical strands under axial load. Elongation is controlled by monomer transport which suffer entrapment due to excess PilT in the cell periplasm. Our analysis shows excellent agreement with a host of experimental observations and we present a possible biophysical relevance of model parameters through a mechano-chemical stall force map. PMID:25502696

  8. Conventional physics can explain cold fusion excess heat

    NASA Astrophysics Data System (ADS)

    Chubb, S. R.

    In 1989, when Fleischmann, Pons and Hawkins (FP), claimed they had created room temperature, nuclear fusion in a solid, a firestorm of controversy erupted. Beginning in 1991, the Office of Naval Research began a decade-long study of the FP excess heat effect. This effort documented the fact that the excess heat that FP observed is the result of a form of nuclear fusion that can occur in solids at reduced temperature, dynamically, through a deuteron (d)+d□4He reaction, without high-energy particles or □ rays. A key reason this fact has not been accepted is the lack of a cogent argument, based on fundamental physical ideas, justifying it. In the paper, this question is re-examined, based on a generalization of conventional energy band theory that applies to finite, periodic solids, in which d's are allowed to occupy wave-like, ion band states, similar to the kinds of states that electrons occupy in ordinary metals. Prior to being experimentally observed, the Ion Band State Theory (IBST) of cold fusion predicted a potential d+d□4He reaction, without high energy particles, would explain the excess heat, the 4He would be found in an unexpected place (outside heat-producing electrodes), and high-loading, x□1, in PdDx, would be required.

  9. Crash risk: How cycling flow can help explain crash data.

    PubMed

    Dozza, Marco

    2016-05-12

    Crash databases are commonly queried to infer crash causation, prioritize countermeasures to prevent crashes, and evaluate safety systems. However, crash databases, which may be compiled from police and hospital records, alone cannot provide estimates of crash risk. Moreover, they fail to capture road user behavior before the crash. In Sweden, as in many other countries, crash databases are particularly sterile when it comes to bicycle crashes. In fact, not only are bicycle crashes underreported in police reports, they are also poorly documented in hospital reports. Nevertheless, these reports are irreplaceable sources of information, clearly highlighting the surprising prevalence of single-bicycle crashes and hinting at some cyclist behaviors, such as alcohol consumption, that may increase crash risk. In this study, we used exposure data from 11 roadside stations measuring cyclist flow in Gothenburg to help explain crash data and estimate risk. For instance, our results show that crash risk is greatest at night on weekends, and that this risk is larger for single-bicycle crashes than for crashes between a cyclist and another motorist. This result suggests that the population of night-cyclists on weekend nights is particularly prone to specific crash types, which may be influenced by specific contributing factors (such as alcohol), and may require specific countermeasures. Most importantly, our results demonstrate that detailed exposure data can help select, filter, aggregate, highlight, and normalize crash data to obtain a sharper view of the cycling safety problem, to achieve a more fine-tuned intervention.

  10. Gelatinization temperature of rice explained by polymorphisms in starch synthase.

    PubMed

    Waters, Daniel L E; Henry, Robert J; Reinke, Russell F; Fitzgerald, Melissa A

    2006-01-01

    The cooking quality of rice is associated with the starch gelatinization temperature (GT). Rice genotypes with low GT have probably been selected for their cooking quality by humans during domestication. We now report polymorphisms in starch synthase IIa (SSIIa) that explain the variation in rice starch GT. Sequence analysis of the eight exons of SSIIa identified significant polymorphism in only exon 8. These single nucleotide polymorphisms (SNPs) were determined in 70 diverse genotypes of rice. Two SNPs could classify all 70 genotypes into either high GT or low GT types which differed in GT by 8 degrees C. 'A' rather than 'G' at base 2412 determined whether a methionine or valine was present at the corresponding amino acid residue in SSIIa, whilst two adjacent SNPs at bases 2543 and 2544 coded for either leucine (GC) or phenylalanine (TT). Rice varieties with high GT starch had a combination of valine and leucine at these residues. In contrast, rice varieties with low GT starch had a combination of either methionine and leucine or valine and phenylalanine at these same residues. At least two distinct polymorphisms have apparently been selected for their desirable cooking qualities in the domestication of rice.

  11. Can unified theories of biodiversity explain mammalian macroecological patterns?

    PubMed Central

    Jones, Kate E.; Blackburn, Tim M.; Isaac, Nick J. B.

    2011-01-01

    The idea of a unifying theory of biodiversity linking the diverse array of macroecological patterns into a common theoretical framework is very appealing. We explore this idea to examine currently proposed unified theories of biodiversity (UTBs) and their predictions. Synthesizing the literature on the macroecological patterns of mammals, we critically evaluate the evidence to support these theories. We find general qualitative support for the UTBs' predictions within mammals, but rigorous testing is hampered by the types of data typically collected in studies of mammals. In particular, abundance is rarely estimated for entire mammalian communities or of individual species in multiple locations, reflecting the logistical challenges of studying wild mammal populations. By contrast, there are numerous macroecological patterns (especially allometric scaling relationships) that are extremely well characterized for mammals, but which fall outside the scope of current UTBs. We consider how these theories might be extended to explain mammalian biodiversity patterns more generally. Specifically, we suggest that UTBs need to incorporate the dimensions of geographical space, species' traits and time to reconcile theory with pattern. PMID:21807736

  12. Eucalyptus foliar chemistry explains selective feeding by koalas

    PubMed Central

    Moore, Ben D; Foley, William J; Wallis, Ian R; Cowling, Ann; Handasyde, Kathrine A

    2005-01-01

    The koala is the quintessential specialist herbivore, feeding almost exclusively on Eucalyptus foliage. Consequently, the limitations imposed on the koala's diet by plant defences indicate the extent to which evolutionary adaptations allow mammalian herbivores to circumvent such defences. We tested whether a recently discovered group of plant secondary metabolites, the formylated phloroglucinol compounds (FPCs), deters koalas from feeding on some eucalypt foliage. We found that captive koalas ate less foliage in a single night from trees with high FPC concentrations. Individual trees also differ in the types of FPC they possess, but for a given eucalypt species, most FPCs were similarly effective deterrents. Two closely related and sympatric eucalypt species could be clearly separated by the amounts that koalas ate from each; however, this difference could not be explained by total FPC concentrations alone. We suggest, that in this case, the presence of a distinct type of FPC deters koala herbivory on the less palatable species, and may have facilitated the evolutionary divergence of these species. We conclude that plant defences probably play an important role in determining the distribution and abundance of koalas. PMID:17148129

  13. Fatal attraction: Explaining Russia's sensitive nuclear transfers to Iran

    NASA Astrophysics Data System (ADS)

    Kuchinsky, Leah R.

    This paper explores Russia's sensitive nuclear assistance to Iran in an effort to determine why a supplier state might proliferate against its own apparent security interests. The goal is to help readers understand the supply-side dynamics of nuclear proliferation. Through careful reconstruction of the historical narrative, using open source data, this study tests the plausibility of a "fatalistic calculus" explanation, identified by Stephen Sestanovich as a possible driver for Russia's behavior. According to the hypothesis, Russia has cooperated with Iran as a way both to stay in the good graces of a neighbor that is suspected of developing nuclear weapons and to win short-term influence and profits. The paper also examines the role of other factors advanced in the existing supply-side literature, such as economic motives identified by physicist and nonproliferation scholar David Albright. The findings show that bureaucratic, economic and fatalistic factors have each played a role in motivating Russia's cooperation with Iran, with their relative importance shifting over time. Fatalism begets a strategy of Russian "minimaxing," in the lexicon of Russia scholar Robert Freedman, wherein Russia attempts to minimize damage to its relationship with the U.S. while maximizing influence in Iran via nuclear cooperation. Fatalism, as actualized by minimaxing, best explains Russia's behavior after former Russian president Vladmir Putin came to power, when the bureaucratic and economic arguments become less cogent.

  14. Are socioeconomic disparities in diet quality explained by diet cost?

    PubMed Central

    Monsivais, Pablo; Aggarwal, Anju; Drewnowski, Adam

    2014-01-01

    Background Socioeconomic disparities in nutrition are well documented. This study tested the hypothesis that socioeconomic differences in nutrient intakes can be accounted for, in part, by diet cost. Methods A representative sample of 1,295 adults in King County (WA) was surveyed in 2008–2009 and usual dietary intakes were assessed based on a food frequency questionnaire (FFQ). Monetary value of individual diets was estimated using local retail supermarket prices for 384 foods. Nutrients of concern as identified by the 2005 Dietary Guidelines Advisory Committee were fiber, vitamins A, C and E, calcium, magnesium and potassium. A nutrient density score based on all seven nutrients was another dependent measure. General linear models and linear regressions were used to examine associations among education and income, nutrient density measure and diet cost. Analyses were conducted in 2009–2010. Results Controlling for energy and other covariates, higher-cost diets were significantly higher in all seven nutrients and in overall nutrient density. Higher education and income were positively and significantly associated with the nutrient density measure, but these effects were greatly attenuated with the inclusion of the cost variable in the model. Conclusions Socioeconomic differences in nutrient intake can be substantially explained by the monetary cost of the diet. The higher cost of more nutritious diets may contribute to socioeconomic disparities in health and should be taken into account in the formulation of nutrition and public health policy. PMID:21148819

  15. Sexual selection explains Rensch's rule of size dimorphism in shorebirds.

    PubMed

    Székely, Tamás; Freckleton, Robert P; Reynolds, John D

    2004-08-17

    Sexual size dimorphism shows a remarkably widespread relationship to body size in the animal kingdom: within lineages, it decreases with size when females are the larger sex, but it increases with size when males are the larger sex. Here we demonstrate that this pattern, termed Rensch's rule, exists in shorebirds and allies (Charadriides), and it is determined by two components of sexual selection: the intensity of sexual selection acting on males and the agility of the males' display. These effects are interactive so that the effect of sexual selection on size dimorphism depends on male agility. As a control, we also examine dimorphism in bill length, which is a functionally selected trait. As such, dimorphism in bill length neither exhibits Rensch's rule nor is associated with sexual selection and display. Our results show that variation among taxa in the direction and magnitude of sexual size dimorphism, as manifested as Rensch's rule, can be explained by the interaction between the form and strength of sexual selection acting on each sex in relation to body size.

  16. Glacial ocean circulation and stratification explained by reduced atmospheric temperature.

    PubMed

    Jansen, Malte F

    2017-01-03

    Earth's climate has undergone dramatic shifts between glacial and interglacial time periods, with high-latitude temperature changes on the order of 5-10 °C. These climatic shifts have been associated with major rearrangements in the deep ocean circulation and stratification, which have likely played an important role in the observed atmospheric carbon dioxide swings by affecting the partitioning of carbon between the atmosphere and the ocean. The mechanisms by which the deep ocean circulation changed, however, are still unclear and represent a major challenge to our understanding of glacial climates. This study shows that various inferred changes in the deep ocean circulation and stratification between glacial and interglacial climates can be interpreted as a direct consequence of atmospheric temperature differences. Colder atmospheric temperatures lead to increased sea ice cover and formation rate around Antarctica. The associated enhanced brine rejection leads to a strongly increased deep ocean stratification, consistent with high abyssal salinities inferred for the last glacial maximum. The increased stratification goes together with a weakening and shoaling of the interhemispheric overturning circulation, again consistent with proxy evidence for the last glacial. The shallower interhemispheric overturning circulation makes room for slowly moving water of Antarctic origin, which explains the observed middepth radiocarbon age maximum and may play an important role in ocean carbon storage.

  17. Glacial ocean circulation and stratification explained by reduced atmospheric temperature

    PubMed Central

    Jansen, Malte F.

    2017-01-01

    Earth’s climate has undergone dramatic shifts between glacial and interglacial time periods, with high-latitude temperature changes on the order of 5–10 °C. These climatic shifts have been associated with major rearrangements in the deep ocean circulation and stratification, which have likely played an important role in the observed atmospheric carbon dioxide swings by affecting the partitioning of carbon between the atmosphere and the ocean. The mechanisms by which the deep ocean circulation changed, however, are still unclear and represent a major challenge to our understanding of glacial climates. This study shows that various inferred changes in the deep ocean circulation and stratification between glacial and interglacial climates can be interpreted as a direct consequence of atmospheric temperature differences. Colder atmospheric temperatures lead to increased sea ice cover and formation rate around Antarctica. The associated enhanced brine rejection leads to a strongly increased deep ocean stratification, consistent with high abyssal salinities inferred for the last glacial maximum. The increased stratification goes together with a weakening and shoaling of the interhemispheric overturning circulation, again consistent with proxy evidence for the last glacial. The shallower interhemispheric overturning circulation makes room for slowly moving water of Antarctic origin, which explains the observed middepth radiocarbon age maximum and may play an important role in ocean carbon storage. PMID:27994158

  18. Global patterns in endemism explained by past climatic change.

    PubMed

    Jansson, Roland

    2003-03-22

    I propose that global patterns in numbers of range-restricted endemic species are caused by variation in the amplitude of climatic change occurring on time-scales of 10-100 thousand years (Milankovitch oscillations). The smaller the climatic shifts, the more probable it is that palaeoendemics survive and that diverging gene pools persist without going extinct or merging, favouring the evolution of neoendemics. Using the change in mean annual temperature since the last glacial maximum, estimated from global circulation models, I show that the higher the temperature change in an area, the fewer endemic species of mammals, birds, reptiles, amphibians and vascular plants it harbours. This relationship was robust to variation in area (for areas greater than 10(4) km2), latitudinal position, extent of former glaciation and whether or not areas are oceanic islands. Past climatic change was a better predictor of endemism than annual temperature range in all phylads except amphibians, suggesting that Rapoport's rule (i.e. species range sizes increase with latitude) is best explained by the increase in the amplitude of climatic oscillations towards the poles. Globally, endemic-rich areas are predicted to warm less in response to greenhouse-gas emissions, but the predicted warming would cause many habitats to disappear regionally, leading to species extinctions.

  19. Cultural values: can they explain self-reported health?

    PubMed

    Roudijk, Bram; Donders, Rogier; Stalmeier, Peep

    2017-06-01

    Self-reported health (SRH) is a measure widely used in health research and population studies. Differences in SRH have been observed between countries and cultural values have been hypothesized to partly explain such differences. Cultural values can be operationalized by two cultural dimensions using the World Values Survey (WVS), namely the traditional/rational-secular and the survival/self-expression dimension. We investigate whether there is an association between the WVS cultural dimensions and SRH, both within and between countries. Data from 51 countries in the WVS is used and combined with macroeconomic data from the Worldbank database. The association between SRH and the WVS cultural dimensions is tested within each of the 51 countries and multilevel mixed models are used to test differences between these countries. Socio-demographic and macroeconomic variables are used to correct for non-cultural variables related to SRH. Within countries, the survival/self-expression dimension was positively associated with SRH, while in most countries there was a negative association for the traditional/rational-secular dimension. Values range between 4 and 17% within countries. Further analyses show that the associations within countries and between countries are similar. Controlling for macroeconomic and socio-demographic factors did not change our results. The WVS cultural dimensions predict SRH within and between countries. Contrary to our expectations, traditional/rational-secular values were negatively associated with SRH. As SRH is associated with cultural values between countries, cultural values could be considered when interpreting SRH between countries.

  20. Metacommunity theory explains the emergence of food web complexity

    PubMed Central

    Pillai, Pradeep; Gonzalez, Andrew; Loreau, Michel

    2011-01-01

    Food webs are highly complex ecological networks, dynamic in both space and time. Metacommunity models are now at the core of unified theories of biodiversity, but to date they have not addressed food web complexity. Here we show that metacommunity theory can explain the emergence of species-rich food webs with complex network topologies. Our analysis shows that network branching in the food web is maximized at intermediate colonization rates and limited dispersal scales, which also leads to concomitant peaks in species diversity. Increased food web complexity and species diversity are made possible by the structural role played by network branches that are supported by omnivore and generalist feeding links. Thus, in contrast to traditional food web theory, which emphasizes the destabilizing effect of omnivory feeding in closed systems, metacommunity theory predicts that these feeding links, which are commonly observed in empirical food webs, play a critical structural role as food webs assemble in space. As this mechanism functions at the metacommunity level, evidence for its operation in nature will be obtained through multiscale surveys of food web structure. Finally, we apply our theory to reveal the effects of habitat destruction on network complexity and metacommunity diversity. PMID:22084089

  1. Learning dynamics explains human behaviour in prisoner's dilemma on networks.

    PubMed

    Cimini, Giulio; Sánchez, Angel

    2014-05-06

    Cooperative behaviour lies at the very basis of human societies, yet its evolutionary origin remains a key unsolved puzzle. Whereas reciprocity or conditional cooperation is one of the most prominent mechanisms proposed to explain the emergence of cooperation in social dilemmas, recent experimental findings on networked Prisoner's Dilemma games suggest that conditional cooperation also depends on the previous action of the player-namely on the 'mood' in which the player is currently in. Roughly, a majority of people behave as conditional cooperators if they cooperated in the past, whereas they ignore the context and free ride with high probability if they did not. However, the ultimate origin of this behaviour represents a conundrum itself. Here, we aim specifically to provide an evolutionary explanation of moody conditional cooperation (MCC). To this end, we perform an extensive analysis of different evolutionary dynamics for players' behavioural traits-ranging from standard processes used in game theory based on pay-off comparison to others that include non-economic or social factors. Our results show that only a dynamic built upon reinforcement learning is able to give rise to evolutionarily stable MCC, and at the end to reproduce the human behaviours observed in the experiments.

  2. Explaining the electroweak scale and stabilizing moduli in M theory

    SciTech Connect

    Acharya, Bobby S.; Bobkov, Konstantin; Kane, Gordon L.; Kumar, Piyush; Shao Jing

    2007-12-15

    In a recent paper [B. Acharya, K. Bobkov, G. Kane, P. Kumar, and D. Vaman, Phys. Rev. Lett. 97, 191601 (2006).] it was shown that in fluxless M theory vacua with at least two hidden sectors undergoing strong gauge dynamics and a particular form of the Kaehler potential, all moduli are stabilized by the effective potential and a stable hierarchy is generated, consistent with standard gauge unification. This paper explains the results of [B. Acharya, K. Bobkov, G. Kane, P. Kumar, and D. Vaman, Phys. Rev. Lett. 97, 191601 (2006).] in more detail and generalizes them, finding an essentially unique de Sitter vacuum under reasonable conditions. One of the main phenomenological consequences is a prediction which emerges from this entire class of vacua: namely, gaugino masses are significantly suppressed relative to the gravitino mass. We also present evidence that, for those vacua in which the vacuum energy is small, the gravitino mass, which sets all the superpartner masses, is automatically in the TeV-100 TeV range.

  3. Chance and necessity do not explain the origin of life.

    PubMed

    Trevors, J T; Abel, D L

    2004-01-01

    Where and how did the complex genetic instruction set programmed into DNA come into existence? The genetic set may have arisen elsewhere and was transported to the Earth. If not, it arose on the Earth, and became the genetic code in a previous lifeless, physical-chemical world. Even if RNA or DNA were inserted into a lifeless world, they would not contain any genetic instructions unless each nucleotide selection in the sequence was programmed for function. Even then, a predetermined communication system would have had to be in place for any message to be understood at the destination. Transcription and translation would not necessarily have been needed in an RNA world. Ribozymes could have accomplished some of the simpler functions of current protein enzymes. Templating of single RNA strands followed by retemplating back to a sense strand could have occurred. But this process does not explain the derivation of "sense" in any strand. "Sense" means algorithmic function achieved through sequences of certain decision-node switch-settings. These particular primary structures determine secondary and tertiary structures. Each sequence determines minimum-free-energy folding propensities, binding site specificity, and function. Minimal metabolism would be needed for cells to be capable of growth and division. All known metabolism is cybernetic--that is, it is programmatically and algorithmically organized and controlled.

  4. Oriented attachment explains cobalt ferrite nanoparticle growth in bioinspired syntheses.

    PubMed

    Wolff, Annalena; Hetaba, Walid; Wißbrock, Marco; Löffler, Stefan; Mill, Nadine; Eckstädt, Katrin; Dreyer, Axel; Ennen, Inga; Sewald, Norbert; Schattschneider, Peter; Hütten, Andreas

    2014-01-01

    Oriented attachment has created a great debate about the description of crystal growth throughout the last decade. This aggregation-based model has successfully described biomineralization processes as well as forms of inorganic crystal growth, which could not be explained by classical crystal growth theory. Understanding the nanoparticle growth is essential since physical properties, such as the magnetic behavior, are highly dependent on the microstructure, morphology and composition of the inorganic crystals. In this work, the underlying nanoparticle growth of cobalt ferrite nanoparticles in a bioinspired synthesis was studied. Bioinspired syntheses have sparked great interest in recent years due to their ability to influence and alter inorganic crystal growth and therefore tailor properties of nanoparticles. In this synthesis, a short synthetic version of the protein MMS6, involved in nanoparticle formation within magnetotactic bacteria, was used to alter the growth of cobalt ferrite. We demonstrate that the bioinspired nanoparticle growth can be described by the oriented attachment model. The intermediate stages proposed in the theoretical model, including primary-building-block-like substructures as well as mesocrystal-like structures, were observed in HRTEM measurements. These structures display regions of substantial orientation and possess the same shape and size as the resulting discs. An increase in orientation with time was observed in electron diffraction measurements. The change of particle diameter with time agrees with the recently proposed kinetic model for oriented attachment.

  5. Oriented attachment explains cobalt ferrite nanoparticle growth in bioinspired syntheses

    PubMed Central

    Hetaba, Walid; Wißbrock, Marco; Löffler, Stefan; Mill, Nadine; Eckstädt, Katrin; Dreyer, Axel; Ennen, Inga; Sewald, Norbert; Schattschneider, Peter; Hütten, Andreas

    2014-01-01

    Summary Oriented attachment has created a great debate about the description of crystal growth throughout the last decade. This aggregation-based model has successfully described biomineralization processes as well as forms of inorganic crystal growth, which could not be explained by classical crystal growth theory. Understanding the nanoparticle growth is essential since physical properties, such as the magnetic behavior, are highly dependent on the microstructure, morphology and composition of the inorganic crystals. In this work, the underlying nanoparticle growth of cobalt ferrite nanoparticles in a bioinspired synthesis was studied. Bioinspired syntheses have sparked great interest in recent years due to their ability to influence and alter inorganic crystal growth and therefore tailor properties of nanoparticles. In this synthesis, a short synthetic version of the protein MMS6, involved in nanoparticle formation within magnetotactic bacteria, was used to alter the growth of cobalt ferrite. We demonstrate that the bioinspired nanoparticle growth can be described by the oriented attachment model. The intermediate stages proposed in the theoretical model, including primary-building-block-like substructures as well as mesocrystal-like structures, were observed in HRTEM measurements. These structures display regions of substantial orientation and possess the same shape and size as the resulting discs. An increase in orientation with time was observed in electron diffraction measurements. The change of particle diameter with time agrees with the recently proposed kinetic model for oriented attachment. PMID:24605288

  6. Failed Collapsar Jets to Explain Low Luminosity GRB Properties

    NASA Astrophysics Data System (ADS)

    Hamidani, Hamid; Umeda, Hideyuki; Takahashi, Koh

    Using the collapsar scenario for long GRBs [1], we present series of numerical simulations to investigate properties of expanding jets, driven by engines deploying the same total energy (1052 erg), differently. We include a wide range of engine durations (Tinj), from 0.1 to 100 s, as well as different initial opening angles (θ0) for the deployed energy. We employ an AMR 2D special relativistic hydrodynamical code, using a 25 solar mass Wolf-Rayet star as the progenitor [2]. We analyze the effect of the engine duration on the jet's hydrodynamic properties, and discuss the implications on GRB and SN emissions. Our results show that the expanding jet's hydrodynamical properties significantly differ, in particular outflow collimation and relativistic acceleration. The implication of this is that brief engines (with Tinj < Tbreakout, either due to a short Tinj or to a large θ0) represent excellent systems to explain the debated low-luminosity GRBs (llGRBs), displaying two of llGRBs peculiar features: i) the estimated llGRBs rate at least about 100 times higher than that of GRBs [3,4,5], and ii) potentially energetic SN emission [6]. We find that these two features only arise from brief engines. The conclusion is that brief engines dominate collapsars, at least at low redshift.

  7. Phylogeny Explains Variation in The Root Chemistry of Eucalyptus Species.

    PubMed

    Senior, John K; Potts, Brad M; Davies, Noel W; Wooliver, Rachel C; Schweitzer, Jennifer A; Bailey, Joseph K; O'Reilly-Wapstra, Julianne M

    2016-10-01

    Plants are dependent on their root systems for survival, and thus are defended from belowground enemies by a range of strategies, including plant secondary metabolites (PSMs). These compounds vary among species, and an understanding of this variation may provide generality in predicting the susceptibility of forest trees to belowground enemies and the quality of their organic matter input to soil. Here, we investigated phylogenetic patterns in the root chemistry of species within the genus Eucalyptus. Given the known diversity of PSMs in eucalypt foliage, we hypothesized that (i) the range and concentrations of PSMs and carbohydrates in roots vary among Eucalyptus species, and (ii) that phylogenetic relationships explain a significant component of this variation. To test for interspecific variation in root chemistry and the influence of tree phylogeny, we grew 24 Eucalyptus species representing two subgenera (Eucalyptus and Symphyomyrtus) in a common garden for two years. Fine root samples were collected from each species and analyzed for total phenolics, condensed tannins, carbohydrates, terpenes, and formylated phloroglucinol compounds. Compounds displaying significant interspecific variation were mapped onto a molecular phylogeny and tested for phylogenetic signal. Although all targeted groups of compounds were present, we found that phenolics dominated root defenses and that all phenolic traits displayed significant interspecific variation. Further, these compounds displayed a significant phylogenetic signal. Overall, our results suggest that within these representatives of genus Eucalyptus, more closely related species have more similar root chemistry, which may influence their susceptibility to belowground enemies and soil organic matter accrual.

  8. Glacial ocean circulation and stratification explained by reduced atmospheric temperature

    NASA Astrophysics Data System (ADS)

    Jansen, Malte F.

    2017-01-01

    Earth’s climate has undergone dramatic shifts between glacial and interglacial time periods, with high-latitude temperature changes on the order of 5–10 °C. These climatic shifts have been associated with major rearrangements in the deep ocean circulation and stratification, which have likely played an important role in the observed atmospheric carbon dioxide swings by affecting the partitioning of carbon between the atmosphere and the ocean. The mechanisms by which the deep ocean circulation changed, however, are still unclear and represent a major challenge to our understanding of glacial climates. This study shows that various inferred changes in the deep ocean circulation and stratification between glacial and interglacial climates can be interpreted as a direct consequence of atmospheric temperature differences. Colder atmospheric temperatures lead to increased sea ice cover and formation rate around Antarctica. The associated enhanced brine rejection leads to a strongly increased deep ocean stratification, consistent with high abyssal salinities inferred for the last glacial maximum. The increased stratification goes together with a weakening and shoaling of the interhemispheric overturning circulation, again consistent with proxy evidence for the last glacial. The shallower interhemispheric overturning circulation makes room for slowly moving water of Antarctic origin, which explains the observed middepth radiocarbon age maximum and may play an important role in ocean carbon storage.

  9. Two phenomenological constants explain similarity laws in stably stratified turbulence.

    PubMed

    Katul, Gabriel G; Porporato, Amilcare; Shah, Stimit; Bou-Zeid, Elie

    2014-02-01

    In stably stratified turbulent flows, the mixing efficiency associated with eddy diffusivity for heat, or equivalently the turbulent Prandtl number (Pr(t)), is fraught with complex dynamics originating from the scalewise interplay between shear generation of turbulence and its dissipation by density gradients. A large corpus of data and numerical simulations agree on a near-universal relation between Pr(t) and the Richardson number (R(i)), which encodes the relative importance of buoyancy dissipation to mechanical production of turbulent kinetic energy. The Pr(t)-R(i) relation is shown to be derivable solely from the cospectral budgets for momentum and heat fluxes if a Rotta-like return to isotropy closure for the pressure-strain effects and Kolmogorov's theory for turbulent cascade are invoked. The ratio of the Kolmogorov to the Kolmogorov-Obukhov-Corrsin phenomenological constants, and a constant associated with isotropization of the production whose value (= 3/5) has been predicted from Rapid Distortion Theory, explain all the macroscopic nonlinearities.

  10. Explaining imaginal inference by operations in a propositional format.

    PubMed

    Wilton, R N

    1978-01-01

    Solving problems by imaginal inference often seems inefficient for an organism that is manipulating propositions. One explanation for the apparent inefficiency is that the problems are being solved not in propositional format by operations in an analogue format. Imaginal inference might then be the most efficient method compatible with the limitations inherent in the analogue format. In the present paper an alternative rationale is given for the use of imaginal inference by explaining how the processes involved in mental problem solving are related to those in perception: it is suggested that the mechanisms used in problem solving have evolved from a perceptual system in which hypotheses about events in the sensory field are generated from an internal representation of the world. This thesis denies that perception is passive and suggests that originally for perception. Acceptance of the thesis implies that the capabilities of a propositional format in problem solving would be limited. This limitation could account for the apparently inefficient use of that format in imaginal inference.

  11. Binding Pose Flip Explained via Enthalpic and Entropic Contributions

    PubMed Central

    2017-01-01

    The anomalous binding modes of five highly similar fragments of TIE2 inhibitors, showing three distinct binding poses, are investigated. We report a quantitative rationalization for the changes in binding pose based on molecular dynamics simulations. We investigated five fragments in complex with the transforming growth factor β receptor type 1 kinase domain. Analyses of these simulations using Grid Inhomogeneous Solvation Theory (GIST), pKA calculations, and a tool to investigate enthalpic differences upon binding unraveled the various thermodynamic contributions to the different binding modes. While one binding mode flip can be rationalized by steric repulsion, the second binding pose flip revealed a different protonation state for one of the ligands, leading to different enthalpic and entropic contributions to the binding free energy. One binding pose is stabilized by the displacement of entropically unfavored water molecules (binding pose determined by solvation entropy), ligands in the other binding pose are stabilized by strong enthalpic interactions, overcompensating the unfavorable water entropy in this pose (binding pose determined by enthalpic interactions). This analysis elucidates unprecedented details determining the flipping of the binding modes, which can elegantly explain the experimental findings for this system. PMID:28079371

  12. Failed supernovae explain the compact remnant mass function

    SciTech Connect

    Kochanek, C. S.

    2014-04-10

    One explanation for the absence of higher mass red supergiants (16.5 M {sub ☉} ≲ M ≲ 25 M {sub ☉}) as the progenitors of Type IIP supernovae (SNe) is that they die in failed SNe creating black holes. Simulations show that such failed SNe still eject their hydrogen envelopes in a weak transient, leaving a black hole with the mass of the star's helium core (5-8 M {sub ☉}). Here we show that this naturally explains the typical masses of observed black holes and the gap between neutron star and black hole masses without any fine-tuning of stellar mass loss, binary mass transfer, or the SN mechanism, beyond having it fail in a mass range where many progenitor models have density structures that make the explosions more likely to fail. There is no difficulty including this ∼20% population of failed SNe in any accounting of SN types over the progenitor mass function. And, other than patience, there is no observational barrier to either detecting these black hole formation events or limiting their rates to be well below this prediction.

  13. Darwin's mistake: explaining the discontinuity between human and nonhuman minds.

    PubMed

    Penn, Derek C; Holyoak, Keith J; Povinelli, Daniel J

    2008-04-01

    Over the last quarter century, the dominant tendency in comparative cognitive psychology has been to emphasize the similarities between human and nonhuman minds and to downplay the differences as "one of degree and not of kind" (Darwin 1871). In the present target article, we argue that Darwin was mistaken: the profound biological continuity between human and nonhuman animals masks an equally profound discontinuity between human and nonhuman minds. To wit, there is a significant discontinuity in the degree to which human and nonhuman animals are able to approximate the higher-order, systematic, relational capabilities of a physical symbol system (PSS) (Newell 1980). We show that this symbolic-relational discontinuity pervades nearly every domain of cognition and runs much deeper than even the spectacular scaffolding provided by language or culture alone can explain. We propose a representational-level specification as to where human and nonhuman animals' abilities to approximate a PSS are similar and where they differ. We conclude by suggesting that recent symbolic-connectionist models of cognition shed new light on the mechanisms that underlie the gap between human and nonhuman minds.

  14. Explaining homosexuality: philosophical issues, and who cares anyhow?

    PubMed

    Suppe, F

    1994-01-01

    Standard behavioral and biological attempts to explain the etiology of homosexuality are surveyed. These include genetic, physiological (e.g., hormonal), constitutional (e.g., wrong pubic hair configurations), childhood experience, parenting, and psychoanalytic accounts. These are criticized from a number of perspectives, including inadequate conceptualization of homosexuality and heterosexuality. The use of path analysis to assess etiological accounts is examined, with particular attention being paid to the Kinsey Institute's Sexual Preference efforts. Drawing from the sociology of science, recent philosophical work on the growth of scientific knowledge, and historical considerations, the legitimacy of homosexual etiology as a scientific research question is examined. It is argued that homosexual etiology is a degenerative research program. The research program's conceptual crudity with respect to sexual identity and sexual orientation precludes it from making any scientific contribution. Thus the claim that homosexual etiology is a legitimate scientific issue is plausible only against the background of a set of late Victorian normative assumptions about "normal love," some surrogate thereof, or a political agenda. Implications of the homosexuality etiology case study for more general philosophical treatments of explanation are considered briefly.

  15. Selection bias explains apparent differential mortality between dialysis modalities.

    PubMed

    Quinn, Robert R; Hux, Janet E; Oliver, Matthew J; Austin, Peter C; Tonelli, Marcello; Laupacis, Andreas

    2011-08-01

    The relative risk of death for patients treated with peritoneal dialysis compared with those treated with hemodialysis appears to change with duration of dialysis therapy. Patients who start dialysis urgently are at high risk for mortality and are treated almost exclusively with hemodialysis, introducing bias to such mortality comparisons. To better isolate the association between dialysis treatment modality and patient mortality, we examined the relative risk for mortality for peritoneal dialysis compared with hemodialysis among individuals who received ≥4 months of predialysis care and who started dialysis electively as outpatients. From a total of 32,285 individuals who received dialysis in Ontario, Canada during a nearly 8-year period, 6,573 patients met criteria for elective, outpatient initiation. We detected no difference in survival between peritoneal dialysis and hemodialysis after adjusting for relevant baseline characteristics. The relative risk of death did not change with duration of dialysis therapy in our primary analysis, but it did change with time when we defined our patient population using the more inclusive criteria typical of previous studies. These results suggest that peritoneal dialysis and hemodialysis associate with similar survival among incident dialysis patients who initiate dialysis electively, as outpatients, after at least 4 months of predialysis care. Selection bias, rather than an effect of the treatment itself, likely explains the previously described change in the relative risk of death over time between hemodialysis and peritoneal dialysis.

  16. Heterogeneity of cells may explain allometric scaling of metabolic rate.

    PubMed

    Takemoto, Kazuhiro

    2015-04-01

    The origin of allometric scaling of metabolic rate is a long-standing question in biology. Several models have been proposed for explaining the origin; however, they have advantages and disadvantages. In particular, previous models only demonstrate either two important observations for the allometric scaling: the variability of scaling exponents and predominance of 3/4-power law. Thus, these models have a dispute over their validity. In this study, we propose a simple geometry model, and show that a hypothesis that total surface area of cells determines metabolic rate can reproduce these two observations by combining two concepts: the impact of cell sizes on metabolic rate and fractal-like (hierarchical) organization. The proposed model both theoretically and numerically demonstrates the approximately 3/4-power law although several different biological strategies are considered. The model validity is confirmed using empirical data. Furthermore, the model suggests the importance of heterogeneity of cell size for the emergence of the allometric scaling. The proposed model provides intuitive and unique insights into the origin of allometric scaling laws in biology, despite several limitations of the model.

  17. Explaining Self and Vicarious Reactance: A Process Model Approach.

    PubMed

    Sittenthaler, Sandra; Jonas, Eva; Traut-Mattausch, Eva

    2016-04-01

    Research shows that people experience a motivational state of agitation known as reactance when they perceive restrictions to their freedoms. However, research has yet to show whether people experience reactance if they merely observe the restriction of another person's freedom. In Study 1, we activated realistic vicarious reactance in the laboratory. In Study 2, we compared people's responses with their own and others' restrictions and found the same levels of experienced reactance and behavioral intentions as well as aggressive tendencies. We did, however, find differences in physiological arousal: Physiological arousal increased quickly after participants imagined their own freedom being restricted, but arousal in response to imagining a friend's freedom being threatened was weaker and delayed. In line with the physiological data, Study 3's results showed that self-restrictions aroused more emotional thoughts than vicarious restrictions, which induced more cognitive responses. Furthermore, in Study 4a, a cognitive task affected only the cognitive process behind vicarious reactance. In contrast, in Study 4b, an emotional task affected self-reactance but not vicarious reactance. We propose a process model explaining the emotional and cognitive processes of self- and vicarious reactance.

  18. Does the General Strain Theory Explain Gambling and Substance Use?

    PubMed

    Greco, Romy; Curci, Antonietta

    2016-11-22

    General Strain Theory (GST: Agnew Criminology 30:47-87, 1992) posits that deviant behaviour results from adaptation to strain and the consequent negative emotions. Empirical research on GST has mainly focused on aggressive behaviours, while only few research studies have considered alternative manifestations of deviance, like substance use and gambling. The aim of the present study is to test the ability of GST to explain gambling behaviours and substance use. Also, the role of family in promoting the adoption of gambling and substance use as coping strategies was verified. Data from 266 families with in mean 8 observations for each group were collected. The multilevel nature of the data was verified before appropriate model construction. The clustered nature of gambling data was analysed by a two-level Hierarchical Linear Model while substance use was analysed by Multivariate Linear Model. Results confirmed the effect of strain on gambling and substance use while the positive effect of depressive emotions on these behaviours was not supported. Also, the impact of family on the individual tendency to engage in addictive behaviours was confirmed only for gambling.

  19. Static stress triggering explains the empirical aftershock distance decay

    NASA Astrophysics Data System (ADS)

    Hainzl, Sebastian; Moradpour, Javad; Davidsen, Jörn

    2014-12-01

    The shape of the spatial aftershock decay is sensitive to the triggering mechanism and thus particularly useful for discriminating between static and dynamic stress triggering. For California seismicity, it has been recently recognized that its form is more complicated than typically assumed consisting of three different regimes with transitions at the scale of the rupture length and the thickness of the crust. The intermediate distance range is characterized by a relative small decay exponent of 1.35 previously declared to relate to dynamic stress triggering. We perform comprehensive simulations of a simple clock-advance model, in which the number of aftershocks is just proportional to the Coulomb-stress change, to test whether the empirical result can be explained by static stress triggering. Similarly to the observations, the results show three scaling regimes. For simulations adapted to the depths and focal mechanisms observed in California, we find a remarkable agreement with the observation over the whole distance range for a fault distribution with fractal dimension of 1.8, which is shown to be in good agreement with an independent analysis of California seismicity.

  20. Eucalyptus foliar chemistry explains selective feeding by koalas.

    PubMed

    Moore, Ben D; Foley, William J; Wallis, Ian R; Cowling, Ann; Handasyde, Kathrine A

    2005-03-22

    The koala is the quintessential specialist herbivore, feeding almost exclusively on Eucalyptus foliage. Consequently, the limitations imposed on the koala's diet by plant defences indicate the extent to which evolutionary adaptations allow mammalian herbivores to circumvent such defences. We tested whether a recently discovered group of plant secondary metabolites, the formylated phloroglucinol compounds (FPCs), deters koalas from feeding on some eucalypt foliage. We found that captive koalas ate less foliage in a single night from trees with high FPC concentrations. Individual trees also differ in the types of FPC they possess, but for a given eucalypt species, most FPCs were similarly effective deterrents. Two closely related and sympatric eucalypt species could be clearly separated by the amounts that koalas ate from each; however, this difference could not be explained by total FPC concentrations alone. We suggest, that in this case, the presence of a distinct type of FPC deters koala herbivory on the less palatable species, and may have facilitated the evolutionary divergence of these species. We conclude that plant defences probably play an important role in determining the distribution and abundance of koalas.

  1. Visual crowding cannot be wholly explained by feature pooling.

    PubMed

    Ester, Edward F; Klee, Daniel; Awh, Edward

    2014-06-01

    Visual perception is dramatically impaired when a peripheral target is embedded within clutter, a phenomenon known as visual crowding. Despite decades of study, the mechanisms underlying crowding remain a matter of debate. Feature pooling models assert that crowding results from a compulsory pooling (e.g., averaging) of target and distractor features. This view has been extraordinarily influential in recent years, so much so that crowding is typically regarded as synonymous with pooling. However, many demonstrations of feature pooling can also be accommodated by a probabilistic substitution model where observers occasionally report a distractor as the target. Here, we directly compared pooling and substitution using an analytical approach sensitive to both alternatives. In four experiments, we asked observers to report the precise orientation of a target stimulus flanked by two irrelevant distractors. In all cases, the observed data were well described by a quantitative model that assumes probabilistic substitution, and poorly described by a quantitative model that assumes that targets and distractors are averaged. These results challenge the widely held assumption that crowding can be wholly explained by compulsory pooling. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  2. Visual crowding cannot be wholly explained by feature pooling

    PubMed Central

    Ester, Edward F.; Klee, Daniel; Awh, Edward

    2014-01-01

    Visual perception is dramatically impaired when a peripheral target is embedded within clutter, a phenomenon known as visual crowding. Despite decades of study, the mechanisms underlying crowding remain a matter of debate. Feature pooling models assert that crowding results from a compulsory pooling (e.g., averaging) of target and distractor features. This view has been extraordinarily influential in recent years, so much so that crowding is typically regarded as synonymous with pooling. However, many demonstrations of feature pooling can also be accommodated by a probabilistic substitution model where observers occasionally report a distractor as the target. Here, we directly compared pooling and substitution using an analytical approach sensitive to both alternatives. In four experiments, we asked observers to report the precise orientation of a target stimulus flanked by two irrelevant distractors. In all cases, the observed data were well-described by a quantitative model that assumes probabilistic substitution, and poorly described by a quantitative model that assumes that targets and distractors are averaged. These results challenge the widely-held assumption that crowding can be wholly explained by compulsory pooling. PMID:24364703

  3. Explaining coherence in coherence masking protection for adults and children

    PubMed Central

    Tarr, Eric; Nittrouer, Susan

    2013-01-01

    Coherence masking protection (CMP) is the phenomenon in which a low-frequency target (typically a first formant) is labeled accurately in poorer signal-to-noise levels when combined with a high-frequency cosignal, rather than presented alone. An earlier study by the authors revealed greater CMP for children than adults, with more resistance to disruptions in harmonicity across spectral components [Nittrouer and Tarr (2011). Atten. Percept. Psychophys. 73, 2606–2623]. That finding was interpreted as demonstrating that children are obliged to process speech signals as broad spectral patterns, regardless of the harmonic structure of the spectral components. The current study tested three alternative, auditory explanations for the observed coherence of target + cosignal: (1) unique spectral shapes of target + cosignal support labeling, (2) periodicity of target + cosignal promotes coherence, and (3) temporal synchrony across target + cosignal reinforces temporal expectancies. Adults, eight-year-olds, and five-year-olds labeled stimuli in five conditions: F1 only and F1 + a constant cosignal (both used previously) were benchmarks for comparing thresholds for F1 + 3 new cosignals. Children again showed greater CMP than adults, but none of the three hypotheses could explain their CMP. It was again concluded that children are obliged to recognize speech signals as broad spectral patterns. PMID:23742373

  4. Causal Inference and Explaining Away in a Spiking Network

    PubMed Central

    Moreno-Bote, Rubén; Drugowitsch, Jan

    2015-01-01

    While the brain uses spiking neurons for communication, theoretical research on brain computations has mostly focused on non-spiking networks. The nature of spike-based algorithms that achieve complex computations, such as object probabilistic inference, is largely unknown. Here we demonstrate that a family of high-dimensional quadratic optimization problems with non-negativity constraints can be solved exactly and efficiently by a network of spiking neurons. The network naturally imposes the non-negativity of causal contributions that is fundamental to causal inference, and uses simple operations, such as linear synapses with realistic time constants, and neural spike generation and reset non-linearities. The network infers the set of most likely causes from an observation using explaining away, which is dynamically implemented by spike-based, tuned inhibition. The algorithm performs remarkably well even when the network intrinsically generates variable spike trains, the timing of spikes is scrambled by external sources of noise, or the network is mistuned. This type of network might underlie tasks such as odor identification and classification. PMID:26621426

  5. Optimization of biomass composition explains microbial growth-stoichiometry relationships.

    PubMed

    Franklin, Oskar; Hall, Edward K; Kaiser, Christina; Battin, Tom J; Richter, Andreas

    2011-02-01

    Integrating microbial physiology and biomass stoichiometry opens far-reaching possibilities for linking microbial dynamics to ecosystem processes. For example, the growth-rate hypothesis (GRH) predicts positive correlations among growth rate, RNA content, and biomass phosphorus (P) content. Such relationships have been used to infer patterns of microbial activity, resource availability, and nutrient recycling in ecosystems. However, for microorganisms it is unclear under which resource conditions the GRH applies. We developed a model to test whether the response of microbial biomass stoichiometry to variable resource stoichiometry can be explained by a trade-off among cellular components that maximizes growth. The results show mechanistically why the GRH is valid under P limitation but not under N limitation. We also show why variability of growth rate-biomass stoichiometry relationships is lower under P limitation than under N or C limitation. These theoretical results are supported by experimental data on macromolecular composition (RNA, DNA, and protein) and biomass stoichiometry from two different bacteria. In addition, compared to a model with strictly homeostatic biomass, the optimization mechanism we suggest results in increased microbial N and P mineralization during organic-matter decomposition. Therefore, this mechanism may also have important implications for our understanding of nutrient cycling in ecosystems.

  6. Incorporating coping into an expectancy framework for explaining drinking behaviour.

    PubMed

    Hasking, Penelope A; Oei, Tian P S

    2008-01-01

    Expectancy Theory has offered much in the way of understanding alcohol use and abuse, and has contributed greatly to prevention and treatment initiatives. However although many cognitive-behavioural treatment approaches are based on expectancy constructs, such as outcome expectancies and self-efficacy, high relapse rates imply that expectancy theory may be too narrow in scope, and that additional variables need to be examined if a comprehensive understanding of drinking behaviour, and better treatment outcomes, are to be achieved. We suggest that the coping strategies an individual employs present one such set of variables that have largely been neglected from an expectancy framework. Although coping skills training is routinely used in prevention and treatment of alcohol problems, coping research has suffered from a poor theoretical framework. In this paper we review the existing research relating expectancies, self-efficacy and coping to drinking behaviour and propose a model which explains both social and dependent drinking, by incorporating coping into an expectancy theory framework. We also outline research and clinical implications of the proposed model.

  7. Learning dynamics explains human behaviour in Prisoner's Dilemma on networks

    PubMed Central

    Cimini, Giulio; Sánchez, Angel

    2014-01-01

    Cooperative behaviour lies at the very basis of human societies, yet its evolutionary origin remains a key unsolved puzzle. Whereas reciprocity or conditional cooperation is one of the most prominent mechanisms proposed to explain the emergence of cooperation in social dilemmas, recent experimental findings on networked Prisoner's Dilemma games suggest that conditional cooperation also depends on the previous action of the player—namely on the ‘mood’ in which the player is currently in. Roughly, a majority of people behave as conditional cooperators if they cooperated in the past, whereas they ignore the context and free ride with high probability if they did not. However, the ultimate origin of this behaviour represents a conundrum itself. Here, we aim specifically to provide an evolutionary explanation of moody conditional cooperation (MCC). To this end, we perform an extensive analysis of different evolutionary dynamics for players' behavioural traits—ranging from standard processes used in game theory based on pay-off comparison to others that include non-economic or social factors. Our results show that only a dynamic built upon reinforcement learning is able to give rise to evolutionarily stable MCC, and at the end to reproduce the human behaviours observed in the experiments. PMID:24554577

  8. Proteobacteria explain significant functional variability in the human gut microbiome.

    PubMed

    Bradley, Patrick H; Pollard, Katherine S

    2017-03-23

    While human gut microbiomes vary significantly in taxonomic composition, biological pathway abundance is surprisingly invariable across hosts. We hypothesized that healthy microbiomes appear functionally redundant due to factors that obscure differences in gene abundance between individuals. To account for these biases, we developed a powerful test of gene variability called CCoDA, which is applicable to shotgun metagenomes from any environment and can integrate data from multiple studies. Our analysis of healthy human fecal metagenomes from three separate cohorts revealed thousands of genes whose abundance differs significantly and consistently between people, including glycolytic enzymes, lipopolysaccharide biosynthetic genes, and secretion systems. Even housekeeping pathways contain a mix of variable and invariable genes, though most highly conserved genes are significantly invariable. Variable genes tend to be associated with Proteobacteria, as opposed to taxa used to define enterotypes or the dominant phyla Bacteroidetes and Firmicutes. These results establish limits on functional redundancy and predict specific genes and taxa that may explain physiological differences between gut microbiomes.

  9. Regional myocardial flow heterogeneity explained with fractal networks

    PubMed Central

    VAN BEEK, JOHANNES H. G. M.; ROGER, STEPHEN A.; BASSINGTHWAIGHTE, JAMES B.

    2010-01-01

    There is explain how the distribution of flow broadens with an increase in the spatial resolution of the measurement, we developed fractal models for vascular networks. A dichotomous branching network of vessels represents the arterial tree and connects to a similar venous network. A small difference in vessel lengths and radii between the two daughter vessels, with the same degree of asymmetry at each branch generation, predicts the dependence of the relative dispersion (mean ± SD) on spatial resolution of the perfusion measurement reasonably well. When the degree of asymmetry increases with successive branching, a better fit to data on sheep and baboons results. When the asymmetry is random, a satisfactory fit is found. These models show that a difference in flow of 20% between the daughter vessels at a branch point gives a relative dispersion of flow of ~30% when the heart is divided into 100–200 pieces. Although these simple models do not represent anatomic features accurately, they provide valuable insight on the heterogeneity of flow within the heart. PMID:2589520

  10. Buzz Factor or Innovation Potential: What Explains Cryptocurrencies' Returns?

    PubMed

    Wang, Sha; Vergne, Jean-Philippe

    2017-01-01

    Cryptocurrencies have become increasingly popular since the introduction of bitcoin in 2009. In this paper, we identify factors associated with variations in cryptocurrencies' market values. In the past, researchers argued that the "buzz" surrounding cryptocurrencies in online media explained their price variations. But this observation obfuscates the notion that cryptocurrencies, unlike fiat currencies, are technologies entailing a true innovation potential. By using, for the first time, a unique measure of innovation potential, we find that the latter is in fact the most important factor associated with increases in cryptocurrency returns. By contrast, we find that the buzz surrounding cryptocurrencies is negatively associated with returns after controlling for a variety of factors, such as supply growth and liquidity. Also interesting is our finding that a cryptocurrency's association with fraudulent activity is not negatively associated with weekly returns-a result that further qualifies the media's influence on cryptocurrencies. Finally, we find that an increase in supply is positively associated with weekly returns. Taken together, our findings show that cryptocurrencies do not behave like traditional currencies or commodities-unlike what most prior research has assumed-and depict an industry that is much more mature, and much less speculative, than has been implied by previous accounts.

  11. Range image statistics can explain the anomalous perception of length.

    PubMed

    Howe, Catherine Q; Purves, Dale

    2002-10-01

    A long-standing puzzle in visual perception is that the apparent extent of a spatial interval (e.g., the distance between two points or the length of a line) does not simply accord with the length of the stimulus but varies as a function of orientation in the retinal image. Here, we show that this anomaly can be explained by the statistical relationship between the length of retinal projections and the length of their real-world sources. Using a laser range scanner, we acquired a database of natural images that included the three-dimensional location of every point in the scenes. An analysis of these range images showed that the average length of a physical interval in three-dimensional space changes systematically as a function of the orientation of the corresponding interval in the projected image, the variation being in good agreement with perceived length. This evidence implies that the perception of visual space is determined by the probability distribution of the possible real-world sources of retinal images.

  12. Hypotheses to explain the origin of species in Amazonia.

    PubMed

    Haffer, J

    2008-11-01

    The main hypotheses proposed to explain barrier formation separating populations and causing the differentiation of species in Amazonia during the course of geological history are based on different factors, as follow: (1) Changes in the distribution of land and sea or in the landscape due to tectonic movements or sea level fluctuations (Paleogeography hypothesis), (2) the barrier effect of Amazonian rivers (River hypothesis), (3) a combination of the barrier effect of broad rivers and vegetational changes in northern and southern Amazonia (River-refuge hypothesis), (4) the isolation of humid rainforest blocks near areas of surface relief in the periphery of Amazonia separated by dry forests, savannas and other intermediate vegetation types during dry climatic periods of the Tertiary and Quaternary (Refuge hypothesis), (5) changes in canopy-density due to climatic reversals (Canopy-density hypothesis) (6) the isolation and speciation of animal populations in small montane habitat pockets around Amazonia due to climatic fluctuations without major vegetational changes (Museum hypothesis), (7) competitive species interactions and local species isolations in peripheral regions of Amazonia due to invasion and counterinvasion during cold/warm periods of the Pleistocene (Disturbance-vicariance hypothesis) and (8) parapatric speciation across steep environmental gradients without separation of the respective populations (Gradient hypothesis). Several of these hypotheses probably are relevant to a different degree for the speciation processes in different faunal groups or during different geological periods. The basic paleogeography model refers mainly to faunal differentiation during the Tertiary and in combination with the Refuge hypothesis. Milankovitch cycles leading to global main hypotheses proposed to explain barrier formation separating populations and causing the differentiation of species in Amazonia during the course of geological history are based on different

  13. Traits, not origin, explain impacts of plants on larval amphibians.

    PubMed

    Cohen, Jillian S; Maerz, John C; Blossey, Bernd

    2012-01-01

    Managing habitats for the benefit of native fauna is a priority for many government and private agencies. Often, these agencies view nonnative plants as a threat to wildlife habitat, and they seek to control or eradicate nonnative plant populations. However, little is known about how nonnative plant invasions impact native fauna, and it is unclear whether managing these plants actually improves habitat quality for resident animals. Here, we compared the impacts of native and nonnative wetland plants on three species of native larval amphibians; we also examined whether plant traits explain the observed impacts. Specifically, we measured plant litter quality (carbon : nitrogen : phosphorus ratios, and percentages of lignin and soluble phenolics) and biomass, along with a suite of environmental conditions known to affect larval amphibians (hydroperiod, temperature, dissolved oxygen, and pH). Hydroperiod and plant traits, notably soluble phenolics, litter C:N ratio, and litter N:P ratio, impacted the likelihood that animals metamorphosed, the number of animals that metamorphosed, and the length of larval period. As hydroperiod decreased, the likelihood that amphibians achieved metamorphosis and the percentage of tadpoles that successfully metamorphosed also decreased. Increases in soluble phenolics, litter N:P ratio, and litter C:N ratio decreased the likelihood that tadpoles achieved metamorphosis, decreased the percentage of tadpoles metamorphosing, decreased metamorph production (total metamorph biomass), and increased the length of larval period. Interestingly, we found no difference in metamorphosis rates and length of larval period between habitats dominated by native and nonnative plants. Our findings have important implications for habitat management. We suggest that to improve habitats for native fauna, managers should focus on assembling a plant community with desirable traits rather than focusing only on plant origin.

  14. Explained and Unexplained Momentum Impulse Transfer Events (MITEs)

    NASA Astrophysics Data System (ADS)

    Bantel, M.; Cunio, P.; Hendrix, D.; Therien, W.

    2016-09-01

    Precision orbit determination (OD) and characterization of resident space objects (RSOs) are fundamental components of Space Situational Awareness (SSA). Over 600 days beginning January 1, 2015, ExoAnalytic Solutions collected more than 60 million correlated astrometric measurements of active and inactive resident RSOs in geosynchronous Earth orbit (GEO) and in the near-GEO region using a global network of ground-based telescopes. Orbit Determination (OD) on several inactive RSOs in sub-synchronous (e.g., spent upper stages) and super-synchronous (e.g., retired satellites) orbits revealed occasional momentum impulse transfer events (MITEs) with detectable In-track velocity changes of 0.2 to 10 mm/s. These MITEs could not be explained using the accepted gravitational model and an isotropic spherical solar radiation acceleration. Two additional radiation pressure models were considered: a Yarkovsky effect and an asymmetric radiation pressure (diffuse ellipsoid), adding one and two additional free parameters to the model, respectively. Both models include a radiation pressure component perpendicular to the solar direction and in the RSO's orbital plane. The Yarkovsky and Ellipsoid radiation pressure, in combination with the RSO traversing the Earth's Umbra, can produce a measureable change in the RSO's mean motion; a delta-v of 0.5 mm/s per season is not uncommon. OD was performed using the three radiation pressure models (Sphere, Yarkovsky, and Ellipsoid) on six inactive RSOs having 9,000 to 35,000 observations over 600 days. The Ellipsoid model was in good agreement with 95% of the observations falling within a window of ± 20 microradians, or approximately ±0.8 km, over the entire 600 day duration, which included three equinox seasons. Data collection and analysis of inactive RSOs aids the SSA mission of precision tracking and characterization of debris in the space environment.

  15. An experimental approach to explain the southern Andes elevational treeline.

    PubMed

    Fajardo, Alex; Piper, Frida I

    2014-05-01

    • The growth limitation hypothesis (GLH) is the most accepted mechanistic explanation for treeline formation, although it is still uncertain whether it applies across taxa. The successful establishment of Pinus contorta--an exotic conifer species in the southern hemisphere--above the Nothofagus treeline in New Zealand may suggest a different mechanism. We tested the GLH in Nothofagus pumilio and Pinus contorta by comparing seedling performance and carbon (C) balance in response to low temperatures.• At a southern Chilean treeline, we grew seedlings of both species 2 m above ground level, to simulate coupling between temperatures at the meristem and in the air (colder), and at ground level, i.e., decoupling air temperature (relatively milder). We recorded soil and air temperatures as well. After 3 yr, we measured seedling survival and biomass (as a surrogate of growth) and determined nonstructural carbohydrates (NSC).• Nothofagus and Pinus did not differ in survival, which, as a whole, was higher at ground level than at the 2-m height. The root-zone temperature for the growing season was 6.6°C. While biomass and NSC decreased significantly for Nothofagus at the 2-m height compared with ground level (C limitation), these trends were not significant for Pinus• The treeline for Nothofagus pumilio is located at an isotherm that fully matches global patterns; however, its physiological responses to low temperatures differed from those of other treeline species. Support for C limitation in N. pumilio but not in P. contorta indicates that the physiological mechanism explaining their survival and growth at treeline may be taxon-dependent. © 2014 Botanical Society of America, Inc.

  16. Do factors related to combustion-based sources explain ...

    EPA Pesticide Factsheets

    Introduction: Spatial heterogeneity of effect estimates in associations between PM2.5 and total non-accidental mortality (TNA) in the United States (US), is an issue in epidemiology. This study uses rate ratios generated from the Multi-City/Multi-Pollutant study (1999-2005) for 313 core-based statistical areas (CBSA) and their metropolitan divisions (MD) to examine combustion-based sources of heterogeneity.Methods: For CBSA/MDs, area-specific log rate ratios (betas) were derived from a model adjusting for time, an interaction with age-group, day of week, and natural splines of current temperature, current dew point, and unconstrained temperature at lags 1, 2, and 3. We assessed the heterogeneity in the betas by linear regression with inverse variance weights, using average NO2, SO2, and CO, which may act as a combustion source proxy, and these pollutants’ correlations with PM2.5. Results: We found that weighted mean PM2.5 association (0.96 percent increase in total non-accidental mortality for a 10 µg/m3 increment in PM2.5) increased by 0.26 (95% confidence interval 0.08 , 0.44) for an interquartile change (0.2) in the correlation of SO2 and PM2.5., but betas showed less dependence on the annual averages of SO2 or NO2. Spline analyses suggest departures from linearity, particularly in a model that examined correlations between PM2.5 and CO.Conclusions: We conclude that correlations between SO2 and PM2.5 as an indicator of combustion sources explains some hete

  17. Explaining the Imperfection of the Molecular Clock of Hominid Mitochondria

    PubMed Central

    Loogväli, Eva-Liis; Kivisild, Toomas; Margus, Tõnu; Villems, Richard

    2009-01-01

    The molecular clock of mitochondrial DNA has been extensively used to date various genetic events. However, its substitution rate among humans appears to be higher than rates inferred from human-chimpanzee comparisons, limiting the potential of interspecies clock calibrations for intraspecific dating. It is not well understood how and why the substitution rate accelerates. We have analyzed a phylogenetic tree of 3057 publicly available human mitochondrial DNA coding region sequences for changes in the ratios of mutations belonging to different functional classes. The proportion of non-synonymous and RNA genes substitutions has reduced over hundreds of thousands of years. The highest mutation ratios corresponding to fast acceleration in the apparent substitution rate of the coding sequence have occurred after the end of the Last Ice Age. We recalibrate the molecular clock of human mtDNA as 7990 years per synonymous mutation over the mitochondrial genome. However, the distribution of substitutions at synonymous sites in human data significantly departs from a model assuming a single rate parameter and implies at least 3 different subclasses of sites. Neutral model with 3 synonymous substitution rates can explain most, if not all, of the apparent molecular clock difference between the intra- and interspecies levels. Our findings imply the sluggishness of purifying selection in removing the slightly deleterious mutations from the human as well as the Neandertal and chimpanzee populations. However, for humans, the weakness of purifying selection has been further exacerbated by the population expansions associated with the out-of Africa migration and the end of the Last Ice Age. PMID:20041137

  18. Openings between Defective Endothelial Cells Explain Tumor Vessel Leakiness

    PubMed Central

    Hashizume, Hiroya; Baluk, Peter; Morikawa, Shunichi; McLean, John W.; Thurston, Gavin; Roberge, Sylvie; Jain, Rakesh K.; McDonald, Donald M.

    2000-01-01

    Leakiness of blood vessels in tumors may contribute to disease progression and is key to certain forms of cancer therapy, but the structural basis of the leakiness is unclear. We sought to determine whether endothelial gaps or transcellular holes, similar to those found in leaky vessels in inflammation, could explain the leakiness of tumor vessels. Blood vessels in MCa-IV mouse mammary carcinomas, which are known to be unusually leaky (functional pore size 1.2–2 μm), were compared to vessels in three less leaky tumors and normal mammary glands. Vessels were identified by their binding of intravascularly injected fluorescent cationic liposomes and Lycopersicon esculentum lectin and by CD31 (PECAM) immunoreactivity. The luminal surface of vessels in all four tumors had a defective endothelial monolayer as revealed by scanning electron microscopy. In MCa-IV tumors, 14% of the vessel surface was lined by poorly connected, overlapping cells. The most superficial lining cells, like endothelial cells, had CD31 immunoreactivity and fenestrae with diaphragms, but they had a branched phenotype with cytoplasmic projections as long as 50 μm. Some branched cells were separated by intercellular openings (mean diameter 1.7 μm; range, 0.3–4.7 μm). Transcellular holes (mean diameter 0.6 μm) were also present but were only 8% as numerous as intercellular openings. Some CD31-positive cells protruded into the vessel lumen; others sprouted into perivascular tumor tissue. Tumors in RIP-Tag2 mice had, in addition, tumor cell-lined lakes of extravasated erythrocytes. We conclude that some tumor vessels have a defective cellular lining composed of disorganized, loosely connected, branched, overlapping or sprouting endothelial cells. Openings between these cells contribute to tumor vessel leakiness and may permit access of macromolecular therapeutic agents to tumor cells. PMID:10751361

  19. Cardiovascular factors explain genetic background differences in VO2max.

    PubMed

    Roy, Jane L P; Hunter, Gary R; Fernandez, Jose R; McCarthy, John P; Larson-Meyer, D Enette; Blaudeau, Tamilane E; Newcomer, Bradley R

    2006-01-01

    The purpose of this study was to further explore factors that may be related to ethnic differences in the maximum rate at which an individual can consume oxygen (VO2max) between 20 African American (AA) and 30 European American (EA) sedentary women who were matched for body weight (kg) and fat-free mass (FFM). VO2max (l/min) was determined during a graded treadmill exercise test. Submaximal steady-state heart rate and submaximal VO2 were determined at a treadmill speed of 1.3 m/sec and a 2.5% grade. Hemoglobin (Hb) was determined by the cyanide method, muscle oxidative capacity by 31P magnetic resonance spectroscopy (ADP time constant), and FFM (kg) by dual-energy x-ray absorptiometry. Genetic classification was self-reported, and in a subset of the sample (N = 32), the determinants of ethnicity were measured by African genetic admixture. AA women had significantly reduced VO2max, Hb levels, and muscle oxidative capacity (longer ADP time constants, P < or = 0.05) than EA women. Submaximal oxygen pulse (O2Psubmax), ADP time constant, Hb, and ethnic background were all significantly related to VO2max (ml/kg/min and ml/kg FFM/min, all P < or = 0.01). By multiple regression modeling, Hb, O2Psubmax, muscle oxidative capacity, and ethnicity were found to explain 61% and 57% of the variance of VO2max in ml/kg/min and ml/kg FFM/min, respectively. Muscle oxidative capacity and O2Psubmax were both significantly and independently related to VO2max in all three models (P < or = 0.05), whereas Hb and ethnicity were not. These results suggest that mitochondrial muscle oxidative capacity and oxygen delivery capabilities, as determined by O2Psubmax, account for most if not all of the ethnic differences in VO2max.

  20. A hypothesis to explain accuracy of wasp resemblances.

    PubMed

    Boppré, Michael; Vane-Wright, Richard I; Wickler, Wolfgang

    2017-01-01

    Mimicry is one of the oldest concepts in biology, but it still presents many puzzles and continues to be widely debated. Simulation of wasps with a yellow-black abdominal pattern by other insects (commonly called "wasp mimicry") is traditionally considered a case of resemblance of unprofitable by profitable prey causing educated predators to avoid models and mimics to the advantage of both (Figure 1a). However, as wasps themselves are predators of insects, wasp mimicry can also be seen as a case of resemblance to one's own potential antagonist. We here propose an additional hypothesis to Batesian and Müllerian mimicry (both typically involving selection by learning vertebrate predators; cf. Table 1) that reflects another possible scenario for the evolution of multifold and in particular very accurate resemblances to wasps: an innate, visual inhibition of aggression among look-alike wasps, based on their social organization and high abundance. We argue that wasp species resembling each other need not only be Müllerian mutualists and that other insects resembling wasps need not only be Batesian mimics, but an innate ability of wasps to recognize each other during hunting is the driver in the evolution of a distinct kind of masquerade, in which model, mimic, and selecting agent belong to one or several species (Figure  1b). Wasp mimics resemble wasps not (only) to be mistaken by educated predators but rather, or in addition, to escape attack from their wasp models. Within a given ecosystem, there will be selection pressures leading to masquerade driven by wasps and/or to mimicry driven by other predators that have to learn to avoid them. Different pressures by guilds of these two types of selective agents could explain the widely differing fidelity with respect to the models in assemblages of yellow jackets and yellow jacket look-alikes.

  1. Vocal traits and diet explain avian sensitivities to anthropogenic noise.

    PubMed

    Francis, Clinton D

    2015-05-01

    Global population growth has caused extensive human-induced environmental change, including a near-ubiquitous transformation of the acoustical environment due to the propagation of anthropogenic noise. Because the acoustical environment is a critical ecological dimension for countless species to obtain, interpret and respond to environmental cues, highly novel environmental acoustics have the potential to negatively impact organisms that use acoustics for a variety of functions, such as communication and predator/prey detection. Using a comparative approach with 308 populations of 183 bird species from 14 locations in Europe, North American and the Caribbean, I sought to reveal the intrinsic and extrinsic factors responsible for avian sensitivities to anthropogenic noise as measured by their habitat use in noisy versus adjacent quiet locations. Birds across all locations tended to avoid noisy areas, but trait-specific differences emerged. Vocal frequency, diet and foraging location predicted patterns of habitat use in response to anthropogenic noise, but body size, nest placement and type, other vocal features and the type of anthropogenic noise (chronic industrial vs. intermittent urban/traffic noise) failed to explain variation in habitat use. Strongly supported models also indicated the relationship between sensitivity to noise and predictive traits had little to no phylogenetic structure. In general, traits associated with hearing were strong predictors - species with low-frequency vocalizations, which experience greater spectral overlap with low-frequency anthropogenic noise tend to avoid noisy areas, whereas species with higher frequency vocalizations respond less severely. Additionally, omnivorous species and those with animal-based diets were more sensitive to noise than birds with plant-based diets, likely because noise may interfere with the use of audition in multimodal prey detection. Collectively, these results suggest that anthropogenic noise is a

  2. Second-Chance Signal Transduction Explains Cooperative Flagellar Switching

    PubMed Central

    Zot, Henry G.; Hasbun, Javier E.; Van Minh, Nguyen

    2012-01-01

    The reversal of flagellar motion (switching) results from the interaction between a switch complex of the flagellar rotor and a torque-generating stationary unit, or stator (motor unit). To explain the steeply cooperative ligand-induced switching, present models propose allosteric interactions between subunits of the rotor, but do not address the possibility of a reaction that stimulates a bidirectional motor unit to reverse direction of torque. During flagellar motion, the binding of a ligand-bound switch complex at the dwell site could excite a motor unit. The probability that another switch complex of the rotor, moving according to steady-state rotation, will reach the same dwell site before that motor unit returns to ground state will be determined by the independent decay rate of the excited-state motor unit. Here, we derive an analytical expression for the energy coupling between a switch complex and a motor unit of the stator complex of a flagellum, and demonstrate that this model accounts for the cooperative switching response without the need for allosteric interactions. The analytical result can be reproduced by simulation when (1) the motion of the rotor delivers a subsequent ligand-bound switch to the excited motor unit, thereby providing the excited motor unit with a second chance to remain excited, and (2) the outputs from multiple independent motor units are constrained to a single all-or-none event. In this proposed model, a motor unit and switch complex represent the components of a mathematically defined signal transduction mechanism in which energy coupling is driven by steady-state and is regulated by stochastic ligand binding. Mathematical derivation of the model shows the analytical function to be a general form of the Hill equation (Hill AV (1910) The possible effects of the aggregation of the molecules of haemoglobin on its dissociation curves. J Physiol 40: iv–vii). PMID:22844429

  3. Dissecting risk: what explains patterns in global flood losses?

    NASA Astrophysics Data System (ADS)

    Jongman, Brenden; Winsemius, Hessel; Aerts, Jeroen; Kron, Wolfgang; Ward, Philip

    2013-04-01

    Reported economic losses from river flooding have been shown to increase globally as a result of changes in hazard (i.e. the chance and characteristics of the flood event), exposure (i.e. the population and assets subject to flooding) and vulnerability (i.e. the capacity of the society to deal with the event). However, the contribution of the individual parts of the risk chain to trends in global losses is still largely unknown due to the traditionally limited data availability on a global scale. Recent work on the spatial modelling of global flood hazard and exposure offers new opportunities for the understanding of global risk. In this paper we present an analysis of reported flood losses in 15 world regions from Munich Re's NatCatSERVICE database for the period 1980 - 2010. We combine the loss statistics with spatial 1km2 resolution flood hazard data from the GLOFRIS global inundation model and data on global population exposure, to identify trends and drivers of risk. Our results show that long term trends in risk are mainly explained by an increase in exposed population and assets, while inter-annual variations are driven by variability in hazard intensity. The analysis indicates that regional differences in vulnerability can be identified as the degree to which trends in flood losses respond to increases in hazard and exposure. These results can be valuable in the understanding of past trends in flood risk and the development of future projections for different regions. The findings are important for scholars, policy makers, re-insurance agencies and international development organisations working on issues related to risk, natural hazards and climate change.

  4. To Explain Copernicus: The Islamic Scientific and Religious Contexts

    NASA Astrophysics Data System (ADS)

    Ragep, F. Jamil

    No one seriously disputes the novelty of Copernicus's monumental decision to put the Earth in motion or its importance for the development of modern science. But that decision can appear quite different when viewed from the perspective of a modern scientist versus that of a contextualist historian. In his recent book To Explain the World, Prof. Weinberg places great store on what he calls aesthetic criteria for understanding Copernicus's choice. The historical record, however, is rather ambiguous on the matter, and if anything supports the view that Copernicus came to his aesthetic justifications (such as the beautiful ordering of the planets) after first reaching his heliocentric theory. So if not aesthetics, what did lead him to go against a two-millenium tradition that placed the Earth firmly in the center of the Cosmos? There are no doubt many factors; one of the most intriguing suggestions, well-argued by Noel Swerdlow, is that Copernicus was led to heliocentrism by his rather conservative desire to restore uniform, circular motion to the heavens and remove the irregularities of Ptolemaic astronomy. Swerdlow has also asserted that this has much to do with Islamic predecessors who were attempting to do the same thing, only within a geocentric framework. In this presentation, I will briefly summarize this Islamic scientific context and then explore the religious beliefs that led not only to the questioning of Ptolemaic scientific authority, including his alleged lack of observational diligence, but also ancient philosophical authority, the latter opening up possibilities for alternative cosmologies, at least one of which included the Earth's motion. Finally, evidence will be presented that connects these Islamic contexts with Copernicus's theories and justifications.

  5. The Amazon River reversal explained by tectonic and surface processes

    NASA Astrophysics Data System (ADS)

    Sacek, V.

    2014-12-01

    The drainage pattern in Amazonia was expressively modified during the mountain building of central and northern Andes. In Early Miocene, the fluvial systems in western Amazonia flowed to the foreland basins and northward to the Caribbean. By Late Miocene the drainage reversal occurred and formed the transcontinental Amazon River, connecting the Andes and the equatorial Atlantic margin. This event is recorded in the stratigraphic evolution of the Foz do Amazonas Basin by the onset of Andean-derived sedimentation. Additionally, an abrupt increase in sedimentation rate after the reversal occurred in the Foz do Amazonas Basin. Based on three-dimensional numerical models that couple surface processes, flexural isostasy and crustal thickening due to orogeny, I concluded that the Miocene drainage reversal can be explained by the flexural and surface processes response to the Andes formation with no need to invoke dynamic topography induced by mantle convection, as previously proposed. I observed that the instant of drainage reversal is directly linked to the rate of crustal thickening in the orogeny, the rate of erosion and, mainly, the efficiency of sediment transport. Moreover, the numerical experiments were able to predict the increase in sedimentation rate in the Amazon fan after the drainage reversal of the Amazon River as observed in the Late Miocene-Pliocene sedimentary record. However, the present numerical model fails to fully reproduce the evolution of the Pebas system, a megawetland in western Amazonia that preceded the drainage reversal. Therefore, further investigation is necessary to evaluate the mechanisms that generated and sustained the Pebas system.

  6. Agricultural management explains historic changes in regional soil carbon stocks.

    PubMed

    van Wesemael, Bas; Paustian, Keith; Meersmans, Jeroen; Goidts, Esther; Barancikova, Gabriela; Easter, Mark

    2010-08-17

    Agriculture is considered to be among the economic sectors having the greatest greenhouse gas mitigation potential, largely via soil organic carbon (SOC) sequestration. However, it remains a challenge to accurately quantify SOC stock changes at regional to national scales. SOC stock changes resulting from SOC inventory systems are only available for a few countries and the trends vary widely between studies. Process-based models can provide insight in the drivers of SOC changes, but accurate input data are currently not available at these spatial scales. Here we use measurements from a soil inventory dating from the 1960s and resampled in 2006 covering the major soil types and agricultural regions in Belgium together with region-specific land use and management data and a process-based model. The largest decreases in SOC stocks occurred in poorly drained grassland soils (clays and floodplain soils), consistent with drainage improvements since 1960. Large increases in SOC in well drained grassland soils appear to be a legacy effect of widespread conversion of cropland to grassland before 1960. SOC in cropland increased only in sandy lowland soils, driven by increasing manure additions. Modeled land use and management impacts accounted for more than 70% of the variation in observed SOC changes, and no bias could be demonstrated. There was no significant effect of climate trends since 1960 on observed SOC changes. SOC monitoring networks are being established in many countries. Our results demonstrate that detailed and long-term land management data are crucial to explain the observed SOC changes for such networks.

  7. EXPLAINING THE GALACTIC INTERSTELLAR DUST GRAIN SIZE DISTRIBUTION FUNCTION

    SciTech Connect

    Casuso, E.; Beckman, J. E.

    2010-04-15

    We present here a new theoretical model designed to explain the interstellar dust grain size distribution function (IDGSDF), and compare its results with previous observationally derived distributions and with previous theoretical models. The range of grain sizes produced in the late stages of stars with different masses is considered, and folded into a model which takes into account the observed changes in the historical local star formation rate. Stars in different mass ranges reach their grain producing epochs at times whose mass dependence is quantifiable, and the range of grain sizes produced has also been estimated as a function of stellar mass. The results show an IDGSDF that has a global slope comparable to the observationally derived plot and three peaks at values of the grain radius comparable to those in the observationally derived distribution, which have their ultimate origin in three major peaks which have been observed in the star formation rate (SFR) over the past 15 Gyr. The model uses grain-grain interactions to modify pre-existing size distributions at lower grain sizes, where collisions appear more important. The interactions include disruption by collisions as well as coagulation to form larger grains. The initial distributions are given a range of initial functions (flat, Gaussian, fractal) for their physical parameters, as well as geometrical forms ranging from spherical to highly elongated. The particles are constrained in an imaginary box, and laws of inelastic collisions are applied. Finally, we combine the two models and produce an IDGSDF which is a notably good match to the observational fit, and specifically at small grain radii reproduces the data better than the 'SFR model' alone.

  8. Can physics help to explain embryonic development? An overview.

    PubMed

    Fleury, V

    2013-10-01

    Recent technical advances including digital imaging and particle image velocimetry can be used to extract the full range of embryonic movements that constitute the instantaneous 'morphogenetic fields' of a developing animal. The final shape of the animal results from the sum over time (integral) of the movements that make up the velocity fields of all the tissue constituents. In vivo microscopy can be used to capture the details of vertebrate development at the earliest embryonic stages. The movements thus observed can be quantitatively compared to physical models that provide velocity fields based on simple hypotheses about the nature of living matter (a visco-elastic gel). This approach has cast new light on the interpretation of embryonic movement, folding, and organisation. It has established that several major discontinuities in development are simple physical changes in boundary conditions. In other words, with no change in biology, the physical consequences of collisions between folds largely explain the morphogenesis of the major structures (such as the head). Other discontinuities result from changes in physical conditions, such as bifurcations (changes in physical behaviour beyond specific yield points). For instance, beyond a certain level of stress, a tissue folds, without any new gene being involved. An understanding of the physical features of movement provides insights into the levers that drive evolution; the origin of animals is seen more clearly when viewed under the light of the fundamental physical laws (Newton's principle, action-reaction law, changes in symmetry breaking scale). This article describes the genesis of a vertebrate embryo from the shapeless stage (round mass of tissue) to the development of a small, elongated, bilaterally symmetric structure containing vertebral precursors, hip and shoulder enlarges, and a head.

  9. Explaining the imperfection of the molecular clock of hominid mitochondria.

    PubMed

    Loogväli, Eva-Liis; Kivisild, Toomas; Margus, Tõnu; Villems, Richard

    2009-12-29

    The molecular clock of mitochondrial DNA has been extensively used to date various genetic events. However, its substitution rate among humans appears to be higher than rates inferred from human-chimpanzee comparisons, limiting the potential of interspecies clock calibrations for intraspecific dating. It is not well understood how and why the substitution rate accelerates. We have analyzed a phylogenetic tree of 3057 publicly available human mitochondrial DNA coding region sequences for changes in the ratios of mutations belonging to different functional classes. The proportion of non-synonymous and RNA genes substitutions has reduced over hundreds of thousands of years. The highest mutation ratios corresponding to fast acceleration in the apparent substitution rate of the coding sequence have occurred after the end of the Last Ice Age. We recalibrate the molecular clock of human mtDNA as 7990 years per synonymous mutation over the mitochondrial genome. However, the distribution of substitutions at synonymous sites in human data significantly departs from a model assuming a single rate parameter and implies at least 3 different subclasses of sites. Neutral model with 3 synonymous substitution rates can explain most, if not all, of the apparent molecular clock difference between the intra- and interspecies levels. Our findings imply the sluggishness of purifying selection in removing the slightly deleterious mutations from the human as well as the Neandertal and chimpanzee populations. However, for humans, the weakness of purifying selection has been further exacerbated by the population expansions associated with the out-of Africa migration and the end of the Last Ice Age.

  10. Negative plant soil feedback explaining ring formation in clonal plants.

    PubMed

    Cartenì, Fabrizio; Marasco, Addolorata; Bonanomi, Giuliano; Mazzoleni, Stefano; Rietkerk, Max; Giannino, Francesco

    2012-11-21

    Ring shaped patches of clonal plants have been reported in different environments, but the mechanisms underlying such pattern formation are still poorly explained. Water depletion in the inner tussocks zone has been proposed as a possible cause, although ring patterns have been also observed in ecosystems without limiting water conditions. In this work, a spatially explicit model is presented in order to investigate the role of negative plant-soil feedback as an additional explanation for ring formation. The model describes the dynamics of the plant biomass in the presence of toxicity produced by the decomposition of accumulated litter in the soil. Our model qualitatively reproduces the emergence of ring patterns of a single clonal plant species during colonisation of a bare substrate. The model admits two homogeneous stationary solutions representing bare soil and uniform vegetation cover which depend only on the ratio between the biomass death and growth rates. Moreover, differently from other plant spatial patterns models, but in agreement with real field observations of vegetation dynamics, we demonstrated that the pattern dynamics always lead to spatially homogeneous vegetation covers without creation of stable Turing patterns. Analytical results show that ring formation is a function of two main components, the plant specific susceptibility to toxic compounds released in the soil by the accumulated litter and the decay rate of these same compounds, depending on environmental conditions. These components act at the same time and their respective intensities can give rise to the different ring structures observed in nature, ranging from slight reductions of biomass in patch centres, to the appearance of marked rings with bare inner zones, as well as the occurrence of ephemeral waves of plant cover. Our results highlight the potential role of plant-soil negative feedback depending on decomposition processes for the development of transient vegetation patterns

  11. Agricultural management explains historic changes in regional soil carbon stocks

    PubMed Central

    van Wesemael, Bas; Paustian, Keith; Meersmans, Jeroen; Goidts, Esther; Barancikova, Gabriela; Easter, Mark

    2010-01-01

    Agriculture is considered to be among the economic sectors having the greatest greenhouse gas mitigation potential, largely via soil organic carbon (SOC) sequestration. However, it remains a challenge to accurately quantify SOC stock changes at regional to national scales. SOC stock changes resulting from SOC inventory systems are only available for a few countries and the trends vary widely between studies. Process-based models can provide insight in the drivers of SOC changes, but accurate input data are currently not available at these spatial scales. Here we use measurements from a soil inventory dating from the 1960s and resampled in 2006 covering the major soil types and agricultural regions in Belgium together with region-specific land use and management data and a process-based model. The largest decreases in SOC stocks occurred in poorly drained grassland soils (clays and floodplain soils), consistent with drainage improvements since 1960. Large increases in SOC in well drained grassland soils appear to be a legacy effect of widespread conversion of cropland to grassland before 1960. SOC in cropland increased only in sandy lowland soils, driven by increasing manure additions. Modeled land use and management impacts accounted for more than 70% of the variation in observed SOC changes, and no bias could be demonstrated. There was no significant effect of climate trends since 1960 on observed SOC changes. SOC monitoring networks are being established in many countries. Our results demonstrate that detailed and long-term land management data are crucial to explain the observed SOC changes for such networks. PMID:20679194

  12. Explaining inconsistencies between data on condom use and condom sales

    PubMed Central

    Meekers, Dominique; Van Rossem, Ronan

    2005-01-01

    Background Several HIV prevention programs use data on condom sales and survey-based data on condom prevalence to monitor progress. However, such indicators are not always consistent. This paper aims to explain these inconsistencies and to assess whether the number of sex acts and the number of condoms used can be estimated from survey data. This would be useful for program managers, as it would enable estimation of the number of condoms needed for different target groups. Methods We use data from six Demographic and Health Surveys to estimate the total annual number of sex acts and number of condoms used. Estimates of the number of sex acts are based on self-reported coital frequency, the proportion reporting intercourse the previous day, and survival methods. Estimates of the number of condoms used are based on self-reported frequency of use, the proportion reporting condom use the previous day and in last intercourse. The estimated number of condoms used is then compared with reported data on condom sales and distribution. Results Analysis of data on the annual number of condoms sold and distributed to the trade reveals very erratic patterns, which reflect stock-ups at various levels in the distribution chain. Consequently, condom sales data are a very poor indicator of the level of condom use. Estimates of both the number of sexual acts and the number of condoms used vary enormously based on the estimation method used. For several surveys, the highest estimate of the annual number of condoms used is tenfold that of the lowest estimate. Conclusions Condom sales to the trade are a poor indicator of levels of condom use, and are therefore insufficient to monitor HIV prevention programs. While survey data on condom prevalence allow more detailed monitoring, converting such data to an estimated number of sex acts and condoms used is not straightforward. The estimation methods yield widely different results, and it is impossible to determine which method is most

  13. Is Titan's shape explained by its meteorology and carbon cycle?

    NASA Astrophysics Data System (ADS)

    Choukroun, M.; Sotin, C.

    2012-04-01

    Titan, Saturn's largest satellite, is unique in the Solar System: it is the only satellite bearing a dense atmosphere and it is the only place besides Earth with stable liquid bodies at its surface. In addition complex organics are produced in its atmosphere by the photolysis of methane, the second most abundant atmospheric molecule that irreversibly produces ethane and other more complex carbon bearing molecules. The Cassini/Huygens mission has revealed that the difference between its equatorial and polar radii is several hundred meters larger than that expected from its spin rate, and that it is in hydrostatic equilibrium. Global circulation models predict a large meridional circulation with upwelling at the summer hemisphere and downwelling at the winter pole where ethane can condense and fall at the surface. Lakes and Mare have been observed at the poles only (Stofan et al., Nature, 2007). Ethane has been spectroscopically identified in one of the lakes (Brown et al., Nature, 2008). The present study investigates the subsidence associated with ethane rain at the poles. As suggested by laboratory experiments, ethane flows very easily in a porous crust made of either pure water ice or methane clathrates. Loading of the lithosphere by liquid hydrocarbons induces a tendency of the polar terrains to subside relative to the lower latitudes terrains. In addition, laboratory experiments suggest that ethane substitutes to methane in a methane clathrate crust. The present study estimates the kinetics of this transformation. It suggests that such a transformation would occur on timescales much smaller than geological timescales. To explain a value of 270 m of the subsidence as determined by the radar instrument onboard the Cassini spacecraft (Zebker et al., Science, 2009), our study predicts that the percolation of ethane liquid in the polar crust should have operated during the last 300 - 1,200 Myr. This number is in agreement with the isotopic age of the atmospheric

  14. Parsimonious snow model explains reindeer population dynamics and ranging behavior

    NASA Astrophysics Data System (ADS)

    Kohler, J.; Aanes, R.; Hansen, B. B.; Loe, L.; Severinsen, T.; Stien, A.

    2008-12-01

    Winter snow is a key factor affecting polar ecosystems. One example is the strong negative correlation of winter precipitation with fluctuations in population in some high-arctic animal populations. Ice layers within and at the base of the snowpack have particularly deleterious effects on such populations. Svalbard reindeer have small home ranges and are vulnerable to local "locked pasture" events due to ground-ice formation. When pastures are locked, reindeer are faced with the decision of staying, living off a diminishing fat store, or trying to escape beyond the unknown spatial borders of the ice. Both strategies may inhibit reproduction and increase mortality, leading to population declines. Here we assess the impact of winter snow and ice on the population dynamics of an isolated herd of Svalbard reindeer near Ny-Ålesund, monitored annually since 1978, with a retrospective analysis of the winter snowpack. Because there are no long-term observational records of snow or snow properties, such as ice layers, we must recourse to snowpack modeling. A parsimonious model of snow and ground-ice thickness is driven with daily temperature and precipitation data collected at a nearby weather station. The model uses the degree-day concept and has three adjustable parameters which are tuned to correlate model snow and ground-ice thicknesses to the limited observations available: April snow accumulation measurements on two local glaciers, and a limited number of ground-ice observations made in recent years. Parameter values used are comparable to those reported elsewhere. We find that modeled mean winter ground-ice thickness explains a significant percentage of the observed variance in reindeer population growth rate. Adding other explanatory parameters, such as modeled mean winter snowpack thickness or previous years' population size does not significanly improve the relation. Furthermore, positioning data from a small subset of reindeer show that model icing events are

  15. Nanoscale Structure Of Organic Matter Explain Its Recalcitrance To Degradation

    NASA Astrophysics Data System (ADS)

    Spagnol, M.; Salati, S.; Papa, G.; Tambone, F.; Adani, F.

    2009-04-01

    Recalcitrance can be defined as the natural resistance of organic matter (OM) to microbial and enzymatic deconstruction (Himmel et al., 2007). The nature of OM recalcitrance remained not completely understood and more studies need above all to elucidate the role of the chemical topography of the OM at nanometer scale. Hydrolytic enzymes responsible of OM degradation have a molecular weight of 20-25 kD, corresponding to a size of about 4 nm, hardly penetrate into micropores (i.e. the pore having a diameter < 2 nm) and small mesopores (i.e. pores having a diameter 2 < 50 nm) of OM structures, so that their activities are confined only to a portion of the total surface (Zimmerman et al., 2004; Chesson, 1997; Adani et al., 2006). As consequence of that the characterization of the organic matter at nano-scale became interesting in view to explain OM recalcitrance. The aim of this work was to asses the effect of the nano-scale structure of OM versus its recalcitrance. The evolution of organic matter of organic matrices was studied in two systems: plant residue-soil system and simulated landfill system. Plant residues were incubated in soil for one year and recalcitrant fraction, i.e. humic acid, was isolated and studied. Laboratory simulated landfill considered organic fraction of municipal solid waste sampled at different stages of evolution from a full scale plant and incubated under anaerobic condition for one year. In addition the nano-scale structure of fossilized OM (leonardite, chair coal and graphite) was detected as used as model of recalcitrant OM. Nano-scale structures were detected by using meso and microporosity detection. In particular microporosity was determined by adsorption method using CO2 at 273 K and Non Local Density Functional Theory (NLDFT) method was applied to measure the CO2 adsorption isotherms. On the other hand mesoporosity was detected by using N2 adsorption method at 77 K. The BET (Brunauer-Emmett-Teller) equation and the BJH (Barret

  16. Thai visitors’ expectations and experiences of explainer interaction within a science museum context

    PubMed Central

    Chen, Ganigar; Sonchaeng, Pichai; Wilkinson, Clare; Willey, Neil; Bultitude, Karen

    2015-01-01

    In Western literature, there is evidence that museum explainers offer significant potential for enhancing visitors’ learning through influencing their knowledge, content, action, behaviour and attitudes. However, little research has focused on the role of explainers in other cultural contexts. This study explored interactions between visitors and museum explainers within the setting of Thailand. Two questionnaires were distributed to 600 visitors and 41 museum explainers. The results demonstrated both potential similarities and differences with Western contexts. Explainers appeared to prefer didactic approaches, focussing on factual knowledge rather than encouraging deep learning. Two-way communication, however, appeared to be enhanced by the use of a ‘pseudo-sibling relationship’ by explainers. Traditional Thai social reserve was reduced through such approaches, with visitors taking on active learning roles. These findings have implications for training museum explainers in non-Western cultures, as well as museum communication practice more generally. PMID:24751689

  17. Thai visitors' expectations and experiences of explainer interaction within a science museum context.

    PubMed

    Kamolpattana, Supara; Chen, Ganigar; Sonchaeng, Pichai; Wilkinson, Clare; Willey, Neil; Bultitude, Karen

    2015-01-01

    In Western literature, there is evidence that museum explainers offer significant potential for enhancing visitors' learning through influencing their knowledge, content, action, behaviour and attitudes. However, little research has focused on the role of explainers in other cultural contexts. This study explored interactions between visitors and museum explainers within the setting of Thailand. Two questionnaires were distributed to 600 visitors and 41 museum explainers. The results demonstrated both potential similarities and differences with Western contexts. Explainers appeared to prefer didactic approaches, focussing on factual knowledge rather than encouraging deep learning. Two-way communication, however, appeared to be enhanced by the use of a 'pseudo-sibling relationship' by explainers. Traditional Thai social reserve was reduced through such approaches, with visitors taking on active learning roles. These findings have implications for training museum explainers in non-Western cultures, as well as museum communication practice more generally. © The Author(s) 2014.

  18. Explaining happiness.

    PubMed

    Easterlin, Richard A

    2003-09-16

    What do social survey data tell us about the determinants of happiness? First, that the psychologists' setpoint model is questionable. Life events in the nonpecuniary domain, such as marriage, divorce, and serious disability, have a lasting effect on happiness, and do not simply deflect the average person temporarily above or below a setpoint given by genetics and personality. Second, mainstream economists' inference that in the pecuniary domain "more is better," based on revealed preference theory, is problematic. An increase in income, and thus in the goods at one's disposal, does not bring with it a lasting increase in happiness because of the negative effect on utility of hedonic adaptation and social comparison. A better theory of happiness builds on the evidence that adaptation and social comparison affect utility less in the nonpecuniary than pecuniary domains. Because individuals fail to anticipate the extent to which adaptation and social comparison undermine expected utility in the pecuniary domain, they allocate an excessive amount of time to pecuniary goals, and shortchange nonpecuniary ends such as family life and health, reducing their happiness. There is need to devise policies that will yield better-informed individual preferences, and thereby increase individual and societal well-being.

  19. Explaining happiness

    PubMed Central

    Easterlin, Richard A.

    2003-01-01

    What do social survey data tell us about the determinants of happiness? First, that the psychologists' setpoint model is questionable. Life events in the nonpecuniary domain, such as marriage, divorce, and serious disability, have a lasting effect on happiness, and do not simply deflect the average person temporarily above or below a setpoint given by genetics and personality. Second, mainstream economists' inference that in the pecuniary domain “more is better,” based on revealed preference theory, is problematic. An increase in income, and thus in the goods at one's disposal, does not bring with it a lasting increase in happiness because of the negative effect on utility of hedonic adaptation and social comparison. A better theory of happiness builds on the evidence that adaptation and social comparison affect utility less in the nonpecuniary than pecuniary domains. Because individuals fail to anticipate the extent to which adaptation and social comparison undermine expected utility in the pecuniary domain, they allocate an excessive amount of time to pecuniary goals, and shortchange nonpecuniary ends such as family life and health, reducing their happiness. There is need to devise policies that will yield better-informed individual preferences, and thereby increase individual and societal well-being. PMID:12958207

  20. LCOM Explained

    DTIC Science & Technology

    1990-07-01

    they will be underutilized; in effect, wasted . The statistics gathered by the LCOM simulation provide clues about how the resource levels should be...Monica, CA: The Rand Corporation. Maher, F., & York, M. (1974, December). Simulating mnencemanning for new weWpo systems: maintenance manpower managmen

  1. Development and Assessment of Self-explaining Skills in College Chemistry Instruction

    NASA Astrophysics Data System (ADS)

    Villalta-Cerdas, Adrian

    The prevalent trend in chemistry instruction relies on what has been described as the classroom game. In this model, students take a passive role and the instructor does all the explaining (thinking), and learning is trivialized to knowing the correct answers (memorizing) and being able to produce them when prompted (regurgitating). The generation of explanations is central to scientific and technological development. In the process of figuring out explanations, the generation of inferences relies on the application of skills associated with scientific behaviors (e.g., analytical reasoning and critical thinking). The process of explanation generation causes a deeper analysis and revision of the scientific models, thus impacting the conceptual understanding of such models. Although the process of generating authentic explanations is closer to the experience of doing science, this process is seldom replicated in science instruction. Self-explaining refers to the generation of inferences about causal connections between objects and events. In science, this may be summarized as making sense of how and why actual or hypothetical phenomena take place. Research findings in educational psychology show that implementing activities that elicit self-explaining improves learning in general and specifically enhances authentic learning in the sciences. Research also suggests that self-explaining influences many aspects of cognition, including acquisition of problem-solving skills and conceptual understanding. Although the evidence that links self-explaining and learning is substantial, most of the research has been conducted in experimental settings. The purpose of this work was to advance knowledge in this area by investigating the effect of different self-explaining tasks on self-explaining behavior and the effect of engaging in different levels of self-explaining on learning chemistry concepts. Unlike most of the research in the field, this work did not focus on advancing

  2. Soil Water and Temperature Explain Canopy Phenology and Onset of Spring in a Semiarid Steppe

    Treesearch

    Lynn M. Moore; William K. Lauenroth; David M. Bell; Daniel R. Schlaepfer

    2015-01-01

    It is well known that the timing of growth and development influences critical life stages of all organisms. „The seasonal dynamics of ecosystems are usually well explained by photoperiod and temperature. However, phenological patterns in water-limited ecosystems are rarely studied and insufficiently explained by these two variables. We tested how onset (i.e.,...

  3. The Role of Perspective Taking in How Children Connect Reference Frames When Explaining Astronomical Phenomena

    ERIC Educational Resources Information Center

    Plummer, Julia D.; Bower, Corinne A.; Liben, Lynn S.

    2016-01-01

    This study investigates the role of perspective-taking skills in how children explain spatially complex astronomical phenomena. Explaining many astronomical phenomena, especially those studied in elementary and middle school, requires shifting between an Earth-based description of the phenomena and a space-based reference frame. We studied 7- to…

  4. Interactions between Defining, Explaining and Classifying: The Case of Increasing and Decreasing Sequences

    ERIC Educational Resources Information Center

    Alcock, Lara; Simpson, Adrian

    2017-01-01

    This paper describes a study in which we investigated relationships between defining mathematical concepts--increasing and decreasing infinite sequences--explaining their meanings and classifying consistently with formal definitions. We explored the effect of defining, explaining or studying a definition on subsequent classification, and the…

  5. Explaining Differences between Retrospective and Traditional Pretest Self-Assessments: Competing Theories and Empirical Evidence

    ERIC Educational Resources Information Center

    Nimon, Kim

    2014-01-01

    Summarizing theory and results of empirical research, this article serves to illustrate why effects measured with retrospective pretests may be subject to bias and may not always be explained by response shift theory. It presents three contending theories to explain the difference between retrospective and traditional pretest results and considers…

  6. The Role of Perspective Taking in How Children Connect Reference Frames When Explaining Astronomical Phenomena

    ERIC Educational Resources Information Center

    Plummer, Julia D.; Bower, Corinne A.; Liben, Lynn S.

    2016-01-01

    This study investigates the role of perspective-taking skills in how children explain spatially complex astronomical phenomena. Explaining many astronomical phenomena, especially those studied in elementary and middle school, requires shifting between an Earth-based description of the phenomena and a space-based reference frame. We studied 7- to…

  7. Interactions between Defining, Explaining and Classifying: The Case of Increasing and Decreasing Sequences

    ERIC Educational Resources Information Center

    Alcock, Lara; Simpson, Adrian

    2017-01-01

    This paper describes a study in which we investigated relationships between defining mathematical concepts--increasing and decreasing infinite sequences--explaining their meanings and classifying consistently with formal definitions. We explored the effect of defining, explaining or studying a definition on subsequent classification, and the…

  8. Content-Free Computer Supports for Self-Explaining: Modifiable Typing Interface and Prompting

    ERIC Educational Resources Information Center

    Chou, Chih-Yueh; Liang, Hung-Ta

    2009-01-01

    Self-explaining, which asks students to generate explanations while reading a text, is a self-constructive activity and is helpful for students' learning. Studies have revealed that prompts by a human tutor promote students' self-explanations. However, most studies on self-explaining focus on spoken self-explanations. This study investigates the…

  9. Content-Free Computer Supports for Self-Explaining: Modifiable Typing Interface and Prompting

    ERIC Educational Resources Information Center

    Chou, Chih-Yueh; Liang, Hung-Ta

    2009-01-01

    Self-explaining, which asks students to generate explanations while reading a text, is a self-constructive activity and is helpful for students' learning. Studies have revealed that prompts by a human tutor promote students' self-explanations. However, most studies on self-explaining focus on spoken self-explanations. This study investigates the…

  10. Explaining local authority choices on public hospital provision in the 1930s: a public policy hypothesis.

    PubMed

    Neville, Julia

    2012-01-01

    This article summarises the findings of recent work on local authority public hospital services in England and Wales in the inter-war years and identifies the lack of a robust hypothesis to explain the variations found, particularly one that would explain the actions of county councils as well as county boroughs. Using public policy techniques on a group of local authorities in the far South West it proposes that variations can be explained by an understanding of the deep core beliefs of councillors, their previous experience of 'commissioner' and 'provider' roles, and the availability or otherwise of a dedicated policy entrepreneur to promote change.

  11. Explaining Local Authority Choices on Public Hospital Provision in the 1930s: A Public Policy Hypothesis

    PubMed Central

    Neville, Julia

    2012-01-01

    This article summarises the findings of recent work on local authority public hospital services in England and Wales in the inter-war years and identifies the lack of a robust hypothesis to explain the variations found, particularly one that would explain the actions of county councils as well as county boroughs. Using public policy techniques on a group of local authorities in the far South West it proposes that variations can be explained by an understanding of the deep core beliefs of councillors, their previous experience of ‘commissioner’ and ‘provider’ roles, and the availability or otherwise of a dedicated policy entrepreneur to promote change. PMID:23752983

  12. A neutral theory with environmental stochasticity explains static and dynamic properties of ecological communities.

    PubMed

    Kalyuzhny, Michael; Kadmon, Ronen; Shnerb, Nadav M

    2015-06-01

    Understanding the forces shaping ecological communities is crucial to basic science and conservation. Neutral theory has made considerable progress in explaining static properties of communities, like species abundance distributions (SADs), with a simple and generic model, but was criticised for making unrealistic predictions of fundamental dynamic patterns and for being sensitive to interspecific differences in fitness. Here, we show that a generalised neutral theory incorporating environmental stochasticity may resolve these limitations. We apply the theory to real data (the tropical forest of Barro Colorado Island) and demonstrate that it much better explains the properties of short-term population fluctuations and the decay of compositional similarity with time, while retaining the ability to explain SADs. Furthermore, the predictions are considerably more robust to interspecific fitness differences. Our results suggest that this integration of niches and stochasticity may serve as a minimalistic framework explaining fundamental static and dynamic characteristics of ecological communities. © 2015 John Wiley & Sons Ltd/CNRS.

  13. Artist: Ken Hodges Composite image explaining Objective and Motivation for Galileo Probe Heat Loads:

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Artist: Ken Hodges Composite image explaining Objective and Motivation for Galileo Probe Heat Loads: Galileo Probe descending into Jupiters Atmosphere shows heat shield separation with parachute deployed. (Ref. JPL P-19180)

  14. Can ionospheric refraction and oblique reflection explain the Canadian 50 MHz IGY radio aurora observations?

    NASA Astrophysics Data System (ADS)

    McDiarmid, D. R.; Watermann, J.; McNamara, A. G.

    1990-10-01

    This paper examines the hypothesis of Uspensky and Williams (1988) that the Canadian International Geophysical Year (IGY) radio aurora measurements of low (1-2 dB/deg) magnetic aspect sensitivity of 48 MHz scatter seen during the IGY in the Canadian sector can be explained by inadequate correction. The ionospheric conditions necessary to enable refraction/reflection to explain the Canadian IGY observations were investigated and were compared with those expected in the E-region ionosphere. It is shown that the refraction/oblique reflection is insufficient to explain the low value of aspect sensitivity deduced from the Canadian IGY auroral radar observations assuming ionospheric parameters typical of extended ionospheric layers; neither can these observations be explained by plasma density structures typical of some visual auroral forms. An alternative explanation is discussed.

  15. Dryden's David Bushman explains the capabilities of the Altus UAV to NASA Langley's Charles Hudgins

    NASA Image and Video Library

    2003-05-27

    David Bushman, unmanned aerial vehicle (UAV) mission manager in NASA Dryden's Airborne Science Program, explains the capabilities of the Altus UAV to Charles Hudgins of NASA Langley's Chemistry and Dynamics Branch.

  16. Sub-Surface Excavation of Transient Craters in Porous Targets: Explaining the Impact Delay

    NASA Astrophysics Data System (ADS)

    Bowling, T. J.; Melosh, H. J.

    2012-03-01

    We numerically investigate the subsurface excavation of the transient crater in the earliest moments after the Deep Impact event. At high target porosities the crater remains hidden from observation long enough to explain the "impact delay."

  17. Airway Differences May Explain Why Asthma Can Be More Serious for Blacks

    MedlinePlus

    ... fullstory_163045.html Airway Differences May Explain Why Asthma Can Be More Serious for Blacks Condition is ... may be one reason why black people with asthma are less responsive to treatment and more likely ...

  18. A Simulation Study to Explain the Variability of Ultrasonic Attenuation Measurement in RTM Composites

    NASA Astrophysics Data System (ADS)

    Lonné, Sébastien; Lhémery, Alain; Thévenot, Françoise

    2004-02-01

    Ultrasonic attenuation is strongly variable and possibly high in parts made of RTM (resin transfer molding) composite that often possess an irregular inner structure. To explain this, models of attenuation phenomena at different scales are used in an overall model of wave propagation: multiple scattering by fibers coupled with viscoelastic losses, viscoelastic losses in pure matrix layers, scattering by porosities and by irregular interface geometry. A statistical study with variable structural parameters successfully explains amplitude variability experimentally observed.

  19. Explaining lifetime criminal arrests among clients of a psychiatric probation and parole service.

    PubMed

    Solomon, P; Draine, J

    1999-01-01

    This study examines the extent to which sociodemographic characteristics, clinical characteristics, substance abuse problems, and the array of lifetime criminal behavior may explain lifetime arrests among offenders supervised by the psychiatric probation and parole service. Three hundred twenty-five clients with new cases at a psychiatric probation and parole service in a large urban center were screened for major psychiatric disorders. They were also interviewed for socio-demographic characteristics, mental health treatment history, criminal behavior, and arrest history. Hierarchical block multiple regression analysis tested a model explaining lifetime arrests. After controlling for age and other demographic variables, the number of lifetime psychiatric hospitalizations and lifetime occurrences of mania diagnosis significantly explained lifetime arrests. The total model explained about 10 percent of the variance in lifetime arrests after controlling for opportunity variables, which explained 45 percent. The explanatory power of lifetime hospitalizations and mania support the contention that symptoms, rather than diagnosis, may be the most important clinical factor in explaining criminal arrest among persons with mental illness. Implications for psychiatric services include the development of effective jail diversion programs.

  20. Explainers' development of science-learner identities through participation in a community of practice

    NASA Astrophysics Data System (ADS)

    Richardson, Anne E.

    The urgent environmental issues of today require science-literate adults to engage in business and political decisions to create solutions. Despite the need, few adults have the knowledge and skills of science literacy. This doctoral dissertation is an analytical case study examining the science-learner identity development of Exploratorium Field Trip Explainers. Located in San Francisco, CA, the Exploratorium is a museum of science, art, and human perception dedicated to nurturing curiosity and exploration. Data collected included semi-structured interviews with sixteen former Field Trip Explainers, participant observation of the current Field Trip Explainer Program, and review of relevant documentation. Data analysis employed constant comparative analysis, guided by the communities of practice theoretical framework (Wenger, 1998) and the National Research Council's (2009) Six Strands of Science Learning. Findings of this research indicate that Exploratorium Field Trip Explainers participate in a community of practice made up of a diverse group of people that values curiosity and openness to multiple ways of learning. Many participants entered the Field Trip Explainer Program with an understanding of science learning as a rigid process reserved for a select group of people; through participation in the Field Trip Explainer community of practice, participants developed an understanding of science learning as accessible and a part of everyday life. The findings of this case study have implications for research, theory, and practice in informal adult science learning, access of non-dominant groups to science learning, and adult workplace learning in communities of practice.

  1. A new explained-variance based genetic risk score for predictive modeling of disease risk.

    PubMed

    Che, Ronglin; Motsinger-Reif, Alison A

    2012-09-25

    The goal of association mapping is to identify genetic variants that predict disease, and as the field of human genetics matures, the number of successful association studies is increasing. Many such studies have shown that for many diseases, risk is explained by a reasonably large number of variants that each explains a very small amount of disease risk. This is prompting the use of genetic risk scores in building predictive models, where information across several variants is combined for predictive modeling. In the current study, we compare the performance of four previously proposed genetic risk score methods and present a new method for constructing genetic risk score that incorporates explained variance information. The methods compared include: a simple count Genetic Risk Score, an odds ratio weighted Genetic Risk Score, a direct logistic regression Genetic Risk Score, a polygenic Genetic Risk Score, and the new explained variance weighted Genetic Risk Score. We compare the methods using a wide range of simulations in two steps, with a range of the number of deleterious single nucleotide polymorphisms (SNPs) explaining disease risk, genetic modes, baseline penetrances, sample sizes, relative risks (RR) and minor allele frequencies (MAF). Several measures of model performance were compared including overall power, C-statistic and Akaike's Information Criterion. Our results show the relative performance of methods differs significantly, with the new explained variance weighted GRS (EV-GRS) generally performing favorably to the other methods.

  2. Explaining mastitis incidence in Dutch dairy farming: the influence of farmers' attitudes and behaviour.

    PubMed

    Jansen, J; van den Borne, B H P; Renes, R J; van Schaik, G; Lam, T J G M; Leeuwis, C

    2009-11-15

    When mastitis incidence increases, either infection pressure has increased or cows' resistance has decreased. This usually indicates that farm management is not optimal. Numerous quantitative studies have demonstrated the effect of management practices on mastitis. In most of these studies, the identified risk factors could explain only part of the variance in mastitis incidence on farms. Several studies suggest that the unexplained variance is caused by farmers' attitudes towards different aspects of mastitis treatment and preventive behaviour. This study aims to determine, to quantify and to specify the extent to which farmers' attitudes, over and above farmers' behaviour, are factors that explain the variation in mastitis incidence, measured in terms of the quantifiable effect of management factors. An extensive survey on self-reported attitudes, behaviour and mastitis incidence was conducted on 336 Dutch dairy farms. Results of multiple linear regression analyses show that farmers' self-reported behaviour and attitudes together explain 48%, 31% and 23% of the variation within, respectively, the average farm bulk milk somatic cell count (BMSCC), the clinical mastitis incidence and the combined clinical and subclinical mastitis incidence. Both behaviour and attitudes explain part of the variance. However, most of the variance in all three dependant measures is explained solely by the attitude variables. The variation in BMSCC value is best explained by (1) farmers' normative frame of reference about mastitis, (2) farmers' perceptions about the control of mastitis and (3) the perceived effect of a BMSCC penalty level. The variation in clinical mastitis is best explained by farmers' perceptions about mastitis control. The variation in the combined clinical and subclinical mastitis incidence rate is best explained by the perceived effect of a BMSCC penalty level and the frequency of contact with others. The results of this study show that farmers' attitudes are a

  3. A balanced motor primitive framework can simultaneously explain motor learning in unimanual and bimanual movements.

    PubMed

    Takiyama, Ken; Sakai, Yutaka

    2017-02-01

    Certain theoretical frameworks have successfully explained motor learning in either unimanual or bimanual movements. However, no single theoretical framework can comprehensively explain motor learning in both types of movement because the relationship between these two types of movement remains unclear. Although our recent model of a balanced motor primitive framework attempted to simultaneously explain motor learning in unimanual and bimanual movements, this model focused only on a limited subset of bimanual movements and therefore did not elucidate the relationships between unimanual movements and various bimanual movements. Here, we extend the balanced motor primitive framework to simultaneously explain motor learning in unimanual and various bimanual movements as well as the transfer of learning effects between unimanual and various bimanual movements; these phenomena can be simultaneously explained if the mean activity of each primitive for various unimanual movements is balanced with the corresponding mean activity for various bimanual movements. Using this balanced condition, we can reproduce the results of prior behavioral and neurophysiological experiments. Furthermore, we demonstrate that the balanced condition can be implemented in a simple neural network model.

  4. Differences in early gesture explain SES disparities in child vocabulary size at school entry.

    PubMed

    Rowe, Meredith L; Goldin-Meadow, Susan

    2009-02-13

    Children from low-socioeconomic status (SES) families, on average, arrive at school with smaller vocabularies than children from high-SES families. In an effort to identify precursors to, and possible remedies for, this inequality, we videotaped 50 children from families with a range of different SES interacting with parents at 14 months and assessed their vocabulary skills at 54 months. We found that children from high-SES families frequently used gesture to communicate at 14 months, a relation that was explained by parent gesture use (with speech controlled). In turn, the fact that children from high-SES families have large vocabularies at 54 months was explained by children's gesture use at 14 months. Thus, differences in early gesture help to explain the disparities in vocabulary that children bring with them to school.

  5. How ocean waves rock the Earth: Two mechanisms explain microseisms with periods 3 to 300 s

    NASA Astrophysics Data System (ADS)

    Ardhuin, Fabrice; Gualtieri, Lucia; Stutzmann, Eléonore

    2015-02-01

    Microseismic activity, recorded everywhere on Earth, is largely due to ocean waves. Recent progress has clearly identified sources of microseisms in the most energetic band, with periods from 3 to 10 s. In contrast, the generation of longer-period microseisms has been strongly debated. Two mechanisms have been proposed to explain seismic wave generation: a primary mechanism, by which ocean waves propagating over bottom slopes generate seismic waves, and a secondary mechanism which relies on the nonlinear interaction of ocean waves. Here we show that the primary mechanism explains the average power, frequency distribution, and most of the variability in signals recorded by vertical seismometers, for seismic periods ranging from 13 to 300 s. The secondary mechanism only explains seismic motions with periods shorter than 13 s. Our results build on a quantitative numerical model that gives access to time-varying maps of seismic noise sources.

  6. LIFE HISTORY. Age-related mortality explains life history strategies of tropical and temperate songbirds.

    PubMed

    Martin, Thomas E

    2015-08-28

    Life history theory attempts to explain why species differ in offspring number and quality, growth rate, and parental effort. I show that unappreciated interactions of these traits in response to age-related mortality risk challenge traditional perspectives and explain life history evolution in songbirds. Counter to a long-standing paradigm, tropical songbirds grow at similar overall rates to temperate species but grow wings relatively faster. These growth tactics are favored by predation risk, both in and after leaving the nest, and are facilitated by greater provisioning of individual offspring by parents. Increased provisioning of individual offspring depends on partitioning effort among fewer young because of constraints on effort from adult and nest mortality. These growth and provisioning responses to mortality risk finally explain the conundrum of small clutch sizes of tropical birds.

  7. Explaining mental health treatment disparities: ethnic and cultural differences in family involvement.

    PubMed

    Snowden, Lonnie R

    2007-09-01

    In a large, representative sample of persons receiving public mental health treatment, we examined whether ethnic minority consumers were more likely than white consumers to live with their families and to receive family support. We then evaluated whether differences observed in family involvement explained treatment disparities observed in outpatient and inpatient mental health services. Results indicated that Asian American and Latino consumers, especially, were considerably more likely than white consumers to live with family members and to receive family support. Ethnocultural differences in living with family did explain treatment intensity disparities whether or not consumers described themselves as dependent on family support. The results support the hypothesis that cultural differences in family involvement and support play a role in explaining mental health treatment disparities.

  8. A proposed theoretical model to explain relative age effects in sport.

    PubMed

    Hancock, David J; Adler, Ashley L; Côté, Jean

    2013-01-01

    Exemplary scientific methods describe concepts and provide theories for further testing. For the field of relative age effects (RAEs) in sport, the scientific method appears to be limited to description. The purpose of this paper is to provide a theoretical model to explain RAEs in sport, which researchers can use to test the effects, as well as to generate new hypotheses and recommendations. Herein, we argue that social agents have the largest influence on RAEs. Specifically, we propose that parents influence RAEs through Matthew effects, coaches influence RAEs through Pygmalion effects and athletes influence RAEs through Galatea effects. Integrating these three theories, we propose a model that explains RAEs through these various social agents. This paper provides a theoretical foundation from which researchers can further understand, explain and eventually use to create policies aimed at limiting the negative effect of relative age in sport.

  9. Witchcraft-explained childhood tragedies in Tlaxcala, and their medical sequelae.

    PubMed

    Fabrega, H; Nutini, H

    1993-03-01

    This paper describes results of a study in Tlaxcala, Mexico, involving the sudden death of infants and children that culturally are explained as resulting from the attack of blood-sucking witches. The attacks of the supernaturals are relatively common occurrences and an elaborate ideology has evolved to explain them. Such an ideology serves to explain what constitutes a major trauma of loss and supernatural assault. Data on a total of 47 cases were collected prospectively. The illness experiences of the parents following these traumas were recorded and their nature and consequences analyzed. The results of the study provide a 'folk medical' epidemiology of sudden infant death, a well identified cultural-ecological stressor. Ideas from cultural, psychological and medical anthropology as well as general medicine and psychiatry are used in the interpretation of the results.

  10. A common stochastic accumulator with effector-dependent noise can explain eye-hand coordination

    PubMed Central

    Gopal, Atul; Viswanathan, Pooja

    2015-01-01

    The computational architecture that enables the flexible coupling between otherwise independent eye and hand effector systems is not understood. By using a drift diffusion framework, in which variability of the reaction time (RT) distribution scales with mean RT, we tested the ability of a common stochastic accumulator to explain eye-hand coordination. Using a combination of behavior, computational modeling and electromyography, we show how a single stochastic accumulator to threshold, followed by noisy effector-dependent delays, explains eye-hand RT distributions and their correlation, while an alternate independent, interactive eye and hand accumulator model does not. Interestingly, the common accumulator model did not explain the RT distributions of the same subjects when they made eye and hand movements in isolation. Taken together, these data suggest that a dedicated circuit underlies coordinated eye-hand planning. PMID:25568161

  11. Do Lower-Body Dimensions and Body Composition Explain Vertical Jump Ability?

    PubMed

    Caia, Johnpaul; Weiss, Lawrence W; Chiu, Loren Z F; Schilling, Brian K; Paquette, Max R; Relyea, George E

    2016-11-01

    Caia, J, Weiss, LW, Chiu, LZF, Schilling, BK, Paquette, MR, and Relyea, GE. Do lower-body dimensions and body composition explain vertical jump ability? J Strength Cond Res 30(11): 3073-3083, 2016-Vertical jump (VJ) capability is integral to the level of success attained by individuals participating in numerous sport and physical activities. Knowledge of factors related to jump performance may help with talent identification and/or optimizing training prescription. Although myriad variables are likely related to VJ, this study focused on determining if various lower-body dimensions and/or body composition would explain some of the variability in performance. Selected anthropometric dimensions were obtained from 50 university students (25 men and 25 women) on 2 occasions separated by 48 or 72 hours. Estimated body fat percentage (BF%), height, body weight, hip width, pelvic width, bilateral quadriceps angle (Q-angle), and bilateral longitudinal dimensions of the feet, leg, thigh, and lower limb were obtained. Additionally, participants completed countermovement VJs. Analysis showed BF% to have the highest correlation with countermovement VJ displacement (r = -0.76, p < 0.001). When examining lower-body dimensions, right-side Q-angle displayed the strongest association with countermovement VJ displacement (r = -0.58, p < 0.001). Regression analysis revealed that 2 different pairs of variables accounted for the greatest variation (66%) in VJ: (a) BF% and sex and (b) BF% and body weight. Regression models involving BF% and lower-body dimensions explained up to 61% of the variance observed in VJ. Although the variance explained by BF% may be increased by using several lower-body dimensions, either sex identification or body weight explains comparatively more. Therefore, these data suggest that the lower-body dimensions measured herein have limited utility in explaining VJ performance.

  12. Morphologies in Solvent-Annealed Clotrimazole Thin Films Explained by Hansen-Solubility Parameters.

    PubMed

    Ehmann, Heike M A; Zimmer, Andreas; Roblegg, Eva; Werzer, Oliver

    2014-03-05

    The induction of different crystal morphologies is of crucial importance for many applications. In this work, the preparation of various crystal morphologies within clotrimazole films on glass substrates is demonstrated. Amorphous clotrimazole thin films were transformed via vapor annealing into crystalline structures; highly monodisperse/multidisperse crystallites, spherulite, or dendritic structures were obtained as the solvent was exchanged. X-ray diffraction experiments reveal that the same polymorph is present for all samples but with varying texture. The achieved morphologies are explained in terms of Hansen-solubility parameters and vapor pressures; thus, the different morphologies and crystal orientations can be explained by solvent-solid interaction strengths within the thin film samples.

  13. STS-45 MS and PLC Sullivan explains camera usage on OV-104's aft flight deck

    NASA Technical Reports Server (NTRS)

    1992-01-01

    STS-45 Mission Specialist (MS) and Payload Commander (PLC) Kathryn D. Sullivan, holding communications kit assembly unit and 70mm HASSELBLAD camera, explains camera usage and Earth observation procedures during a television downlink to the ground. Sullivan is on the aft flight deck of Atlantis, Orbiter Vehicle (OV) 104. Behind Sullivan are the onorbit station control panels with the payload station control panels at her left. The STS-45 crew put together a brief video 'tour' program to explain some of their inflight operations.

  14. Immediate survival focus: synthesizing life history theory and dual process models to explain substance use.

    PubMed

    Richardson, George B; Hardesty, Patrick

    2012-01-01

    Researchers have recently applied evolutionary life history theory to the understanding of behaviors often conceived of as prosocial or antisocial. In addition, researchers have applied cognitive science to the understanding of substance use and used dual process models, where explicit cognitive processes are modeled as relatively distinct from implicit cognitive processes, to explain and predict substance use behaviors. In this paper we synthesized these two theoretical perspectives to produce an adaptive and cognitive framework for explaining substance use. We contend that this framework provides new insights into the nature of substance use that may be valuable for both clinicians and researchers.

  15. Time delay and noise explaining the behaviour of the cell growth in fermentation process

    SciTech Connect

    Ayuobi, Tawfiqullah; Rosli, Norhayati; Bahar, Arifah; Salleh, Madihah Md

    2015-02-03

    This paper proposes to investigate the interplay between time delay and external noise in explaining the behaviour of the microbial growth in batch fermentation process. Time delay and noise are modelled jointly via stochastic delay differential equations (SDDEs). The typical behaviour of cell concentration in batch fermentation process under this model is investigated. Milstein scheme is applied for solving this model numerically. Simulation results illustrate the effects of time delay and external noise in explaining the lag and stationary phases, respectively for the cell growth of fermentation process.

  16. Explaining information technology use with the usefulness scale: a comparison with user age.

    PubMed Central

    Kattan, M. W.; Adams, D. A.

    1994-01-01

    Understanding and predicting the use of information technology is an important problem in healthcare management. The relationships among user characteristics and information technology have generally been weak. This paper describes a recently developed scale that measures perceived usefulness of information technology. Following this description, the scale is compared with user age in ability to explain information technology use. The results suggest perceived usefulness explains a significant proportion of the variance in use (r2 = .13, p < or = 0.0001), while age was not a significant predictor. Implications and suggestions for use of the usefulness scale are discussed. PMID:7950037

  17. STS-45 MS and PLC Sullivan explains camera usage on OV-104's aft flight deck

    NASA Technical Reports Server (NTRS)

    1992-01-01

    STS-45 Mission Specialist (MS) and Payload Commander (PLC) Kathryn D. Sullivan, holding communications kit assembly unit and 70mm HASSELBLAD camera, explains camera usage and Earth observation procedures during a television downlink to the ground. Sullivan is on the aft flight deck of Atlantis, Orbiter Vehicle (OV) 104. Behind Sullivan are the onorbit station control panels with the payload station control panels at her left. The STS-45 crew put together a brief video 'tour' program to explain some of their inflight operations.

  18. No Place to Escape: Explaining the Cultural Revolution to American Students

    ERIC Educational Resources Information Center

    Jiang, Ji-li

    2012-01-01

    In this article the author reflects on her visits to American schools to talk about the experiences she describes in "Red Scarf Girl." In her book, she explains picture by picture, story after story how she and her family lived in darkness, how they were brainwashed, and about the concentration of power in China. She stresses that …

  19. MA-9 ASTRONAUT GORDON COOPER EXPLAINS CAMERA TO BACKUP PILOT ALAN SHEPARD

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Astronaut L. Gordon Cooper explains the 16MM handheld spacecraft camera to his back-up pilot Astronaut Alan Shepard. The camera designed by J. R. Hereford, McDonnell Aircraft Corp., will be used by Cooper during the MA-9 mission.

  20. Explaining and forecasting interannual variability in the flow of the Nile River

    NASA Astrophysics Data System (ADS)

    Siam, M. S.; Eltahir, E. A. B.

    2015-03-01

    This study analyzes extensive data sets collected during the twentieth century and defines four modes of natural variability in the flow of the Nile River, identifying a new significant potential for improving predictability of floods and droughts. Previous studies have identified a significant teleconnection between the Nile flow and the eastern Pacific Ocean. El Niño-Southern Oscillation (ENSO) explains about 25% of the interannual variability in the Nile flow. Here, this study identifies a region in the southern Indian Ocean, with a similarly strong teleconnection to the Nile flow. Sea surface temperature (SST) in the region (50-80° E and 25-35° S) explains 28% of the interannual variability in the flow of the Nile River and, when combined with the ENSO index, the explained variability of the flow of the Nile River increases to 44%. In addition, during those years with anomalous SST conditions in both oceans, this study estimates that indices of the SSTs in the Pacific and Indian oceans can collectively explain up to 84% of the interannual variability in the flow of the Nile. Building on these findings, this study uses the classical Bayesian theorem to develop a new hybrid forecasting algorithm that predicts the Nile flow based on global model predictions of indices of the SST in the eastern Pacific and southern Indian oceans.

  1. Applying a predict-observe-explain sequence in teaching of buoyant force

    NASA Astrophysics Data System (ADS)

    Radovanović, Jelena; Sliško, Josip

    2013-01-01

    An active learning sequence based on the predict-observe-explain teaching strategy is applied to a lesson on buoyant force. The results obtained clearly justify the use of this teaching method and suggest devising a series of activities to enable more effective removal of students’ commonly held alternative conceptions regarding floating and sinking.

  2. Can Spectro-Temporal Complexity Explain the Autistic Pattern of Performance on Auditory Tasks?

    ERIC Educational Resources Information Center

    Samson, Fabienne; Mottron, Laurent; Jemel, Boutheina; Belin, Pascal; Ciocca, Valter

    2006-01-01

    To test the hypothesis that level of neural complexity explain the relative level of performance and brain activity in autistic individuals, available behavioural, ERP and imaging findings related to the perception of increasingly complex auditory material under various processing tasks in autism were reviewed. Tasks involving simple material…

  3. Explaining rigid dieting in normal-weight women: the key role of body image inflexibility.

    PubMed

    Ferreira, Cláudia; Trindade, Inês A; Martinho, Ana

    2016-03-01

    Restrictive dieting is an increasing behavior presented by women in modern societies, independently of their weight. There are several known factors that motivate diet, namely a sense of dissatisfaction with one's body and unfavorable social comparisons based on physical appearance. However, dieting seems to have a paradoxical effect and has been considered a risk factor for weight gain and obesity in women and for maladaptive eating. Nevertheless, the study of the emotional regulation processes that explain the adoption of inflexible and rigid eating behaviors still remains little explored. In this line, the present study aims to explore why normal-weight women engage in highly rigid and inflexible diets. We hypothesize that body and weight dissatisfaction and unfavorable social comparisons based on physical appearance explain the adoption of inflexible eating rules, through the mechanisms of body image inflexibility. The current study comprised 508 normal-weight female college students. Path analyses were conducted to explore the study's hypotheses. Results revealed that the model explained 43 % of inflexible eating and revealed excellent fit indices. Furthermore, the unwillingness to experience unwanted events related to body image (body image inflexibility) mediated the impact of body dissatisfaction and unfavorable social comparisons on the adoption of inflexible eating rules. This study highlights the relevance of body image inflexibility to explain rigid eating attitudes, and it seems to be an important avenue for the development of interventions focusing on the promotion of adaptive attitudes towards body image and eating in young women.

  4. Ahead of the Pack? Explaining the Unequal Distribution of Scholarships in Germany

    ERIC Educational Resources Information Center

    Haas, Christina; Van De Werfhorst, Herman

    2017-01-01

    This article investigates to what extent scholarships are unequally distributed among students in Germany and how these inequalities can be explained. Following sociological theory, the article argues that elites seek qualitative ways of distinguishing themselves in a mass higher education system. Using student surveys, we demonstrate that class…

  5. The Efficacy of the Theory of Reasoned Action to Explain Gambling Behavior in College Students

    ERIC Educational Resources Information Center

    Thrasher, Robert G.; Andrew, Damon P. S.; Mahony, Daniel F.

    2007-01-01

    Shaffer and Hall (1997) have estimated college student gambling to be three times as high as their adult counterparts. Despite a considerable amount of research on gambling, researchers have struggled to develop a universal theory that explains gambling behavior. This study explored the potential of Ajzen and Fishbein's (1980) Theory of Reasoned…

  6. Explaining How Political Actors Gain Strategic Positions: Predictors of Centrality in State Reading Policy Issue Networks

    ERIC Educational Resources Information Center

    Young, Tamara V.; Wang, Yuling; Lewis, Wayne D.

    2016-01-01

    Using data from interviews with 111 reading policy actors from California, Connecticut, Michigan, and Utah, this study explains how individuals acquire central positions in issue networks. Regression analyses showed that the greater a policy actor's reputed influence was and the more similar their preferences were to other members in the network,…

  7. Explaining Self-Harm: Youth Cybertalk and Marginalized Sexualities and Genders

    ERIC Educational Resources Information Center

    McDermott, Elizabeth; Roen, Katrina; Piela, Anna

    2015-01-01

    This study investigates self-harm among young lesbian, gay, bisexual, and trans (LGBT) people. Using qualitative virtual methods, we examined online forums to explore young LGBT people's cybertalk about emotional distress and self-harming. We investigated how youth explained the relationship between self-harm and sexuality and gender. We found…

  8. Explaining and Forecasting Job Satisfaction: The Contribution of Occupational Profiling. Working Paper.

    ERIC Educational Resources Information Center

    Rose, Michael

    The contribution of occupational profiling to explaining and forecasting job satisfaction were analyzed by using data on job satisfaction for 33,249 workers from waves 1-7 of the British Household Panel Survey. Overall job satisfaction gradients were defined for major and minor groups of occupations in the United Kingdom's Standard Occupational…

  9. Explaining the Effectiveness of the Contrast Culture Method for Managing Interpersonal Interactions across Cultures

    ERIC Educational Resources Information Center

    Hiratsuka, Hiroyoshi; Suzuki, Hanako; Pusina, Alexis

    2016-01-01

    One of the current challenges in the field of intercultural education comes from the limited availability of training efficacy studies. The present study focused on explaining the effectiveness of the Contrast Culture Method (CCM) as an intercultural education method for managing interpersonal interactions across cultures between graduate…

  10. Explaining Changing Suicide Rates in Norway 1948-2004: The Role of Social Integration

    ERIC Educational Resources Information Center

    Barstad, Anders

    2008-01-01

    Using Norway 1948-2004 as a case, I test whether changes in variables related to social integration can explain changes in suicide rates. The method is the Box-Jenkins approach to time-series analysis. Different aspects of family integration contribute significantly to the explanation of Norwegian suicide rates in this period. The estimated effect…

  11. How Do Preservice Biology Teachers Explain the Origin of Biological Traits?: A Philosophical Analysis

    ERIC Educational Resources Information Center

    Kampourakis, Kostas; Silveira, Patricia; Strasser, Bruno J.

    2016-01-01

    Research suggests that students tend to explain the origin of biological traits in terms of needs or purposes and/or as the direct product of genes, rather than as the outcome of evolutionary and developmental processes. We suggest that in order for students to be able to construct scientific explanations, it is important to clearly and explicitly…

  12. Explaining pathological changes in axonal excitability through dynamical analysis of conductance-based models

    NASA Astrophysics Data System (ADS)

    Coggan, Jay S.; Ocker, Gabriel K.; Sejnowski, Terrence J.; Prescott, Steven A.

    2011-10-01

    Neurons rely on action potentials, or spikes, to relay information. Pathological changes in spike generation likely contribute to certain enigmatic features of neurological disease, like paroxysmal attacks of pain and muscle spasm. Paroxysmal symptoms are characterized by abrupt onset and short duration, and are associated with abnormal spiking although the exact pathophysiology remains unclear. To help decipher the biophysical basis for 'paroxysmal' spiking, we replicated afterdischarge (i.e. continued spiking after a brief stimulus) in a minimal conductance-based axon model. We then applied nonlinear dynamical analysis to explain the dynamical basis for initiation and termination of afterdischarge. A perturbation could abruptly switch the system between two (quasi-)stable attractor states: rest and repetitive spiking. This bistability was a consequence of slow positive feedback mediated by persistent inward current. Initiation of afterdischarge was explained by activation of the persistent inward current forcing the system to cross a saddle point that separates the basins of attraction associated with each attractor. Termination of afterdischarge was explained by the attractor associated with repetitive spiking being destroyed. This occurred when ultra-slow negative feedback, such as intracellular sodium accumulation, caused the saddle point and stable limit cycle to collide; in that regard, the active attractor is not truly stable when the slowest dynamics are taken into account. The model also explains other features of paroxysmal symptoms, including temporal summation and refractoriness.

  13. How Mothers Explain Their Role in Fostering Their Children's Learning: An Attributional Analysis.

    ERIC Educational Resources Information Center

    Melson, Gail F.; And Others

    Goals of this study were to: (1) assess mothers' perceptions of their role in fostering their preschooler's cognitive learning; (2) examine attributions used by mothers to explain why they experience ease or difficulty helping their preschooler learn; and (3) relate maternal perceived level of ease/difficulty to attributions for the reasons…

  14. Explaining Self-Harm: Youth Cybertalk and Marginalized Sexualities and Genders

    ERIC Educational Resources Information Center

    McDermott, Elizabeth; Roen, Katrina; Piela, Anna

    2015-01-01

    This study investigates self-harm among young lesbian, gay, bisexual, and trans (LGBT) people. Using qualitative virtual methods, we examined online forums to explore young LGBT people's cybertalk about emotional distress and self-harming. We investigated how youth explained the relationship between self-harm and sexuality and gender. We found…

  15. Successful Inaugural Major Comprehensive Campaigns: How Organizational Learning Theory Helps Explain the Process

    ERIC Educational Resources Information Center

    Razafimanjato, Laza Johany

    2016-01-01

    This qualitative study consisted of two case studies of southern public metropolitan universities, which successfully completed inaugural major comprehensive fundraising campaigns. The purpose of the study was to explore how the process of initiating and competing an inaugural comprehensive fundraising campaign was explained by organizational…

  16. Semantic language as a mechanism explaining the association between ADHD symptoms and reading and mathematics underachievement.

    PubMed

    Gremillion, Monica L; Martel, Michelle M

    2012-11-01

    ADHD is associated with academic underachievement, but it remains unclear what mechanism accounts for this association. Semantic language is an underexplored mechanism that provides a developmental explanation for this association. The present study will examine whether semantic language deficits explain the association between ADHD and reading and mathematics underachievement, taking into account alternative explanations for associations, including verbal working memory (WM) impairments, as well as specificity of effects to inattentive and hyperactive-impulsive ADHD symptom domains. Participants in this cross-sectional study were 546 children (54 % male) ages six to twelve (M = 9.77, SD = 1.49). ADHD symptoms were measured via maternal and teacher report during structured interviews and on standardized rating forms. Children completed standardized semantic language, verbal WM, and academic testing. Semantic language fully mediated the ADHD-reading achievement association and partially mediated the ADHD-mathematics achievement association. Verbal WM also partially mediated the ADHD-mathematics association but did not mediate the ADHD-reading achievement association. Results generalized across inattentive and hyperactive-impulsive ADHD symptom domains. Semantic language explained the association between ADHD and reading underachievement and partially explained the association between ADHD and mathematics underachievement. Together, language impairment and WM fully explained the association between ADHD and reading underachievement, in line with developmental models suggesting that language and WM conjointly influence the development of attention and subsequent academic achievement. This work has implication for the development of tailored interventions for academic underachievement in children with ADHD.

  17. What Explains the Rural-Urban Gap in Infant Mortality: Household or Community Characteristics?

    PubMed Central

    VAN DE POEL, ELLEN; O’DONNELL, OWEN; VAN DOORSLAER, EDDY

    2009-01-01

    The rural-urban gap in infant mortality rates is explained by using a new decomposition method that permits identification of the contribution of unobserved heterogeneity at the household and the community level. Using Demographic and Health Survey data for six Francophone countries in Central and West sub-Saharan Africa, we find that differences in the distributions of factors that determine mortality—not differences in their effects—explain almost the entire gap. Higher infant mortality rates in rural areas mainly derive from the rural disadvantage in household characteristics, both observed and unobserved, which explain two-thirds of the gap. Among the observed characteristics, environmental factors—a safe source of drinking water, electricity, and quality of housing materials—are the most important contributors. Community characteristics explain less than one-quarter of the gap, with about two-thirds of this coming from community unobserved heterogeneity and one-third from the existence of a health facility within the community. The effect of disadvantageous environmental conditions—such as limited electricity and water supply—derives both from a lack of community-level infrastructure and from the inability of some households to exploit it when available. Policy needs to operate at both the community and household levels to correct such deficiencies. PMID:20084831

  18. Understanding Middle School Students' Difficulties in Explaining Density Differences from a Language Perspective

    ERIC Educational Resources Information Center

    Seah, Lay Hoon; Clarke, David; Hart, Christina

    2015-01-01

    This study examines how a class of Grade 7 students employed linguistic resources to explain density differences. Drawing from the same data-set as a previous study by, we take a language perspective to investigate the challenges students face in learning the concept of density. Our study thus complements previous research on learning about…

  19. Relevance of Student and Contextual School Variables in Explaining a Student's Severity of Violence Experienced

    ERIC Educational Resources Information Center

    Mooij, Ton

    2015-01-01

    Teachers conceptualise and interpret violent behaviour of secondary students in different ways. They also differ in their estimates of the relevance of student and contextual school variables when explaining the severity of violence experienced by students. Research can assist here by explicating the role of different types of contextual school…

  20. Explaining pathological changes in axonal excitability through dynamical analysis of conductance-based models

    PubMed Central

    Coggan, Jay S; Ocker, Gabriel K; Sejnowski, Terrence J; Prescott, Steven A

    2011-01-01

    Neurons rely on action potentials, or spikes, to relay information. Pathological changes in spike generation likely contribute to certain enigmatic features of neurological disease, like paroxysmal attacks of pain and muscle spasm. Paroxysmal symptoms are characterized by abrupt onset and short duration, and are associated with abnormal spiking although the exact pathophysiology remains unclear. To help decipher the biophysical basis for ‘paroxysmal’ spiking, we replicated afterdischarge (i.e. continued spiking after a brief stimulus) in a minimal conductance-based axon model. We then applied nonlinear dynamical analysis to explain the dynamical basis for initiation and termination of afterdischarge. A perturbation could abruptly switch the system between two (quasi-)stable attractor states: rest and repetitive spiking. This bistability was a consequence of slow positive feedback mediated by persistent inward current. Initiation of afterdischarge was explained by activation of the persistent inward current forcing the system to cross a saddle point that separates the basins of attraction associated with each attractor. Termination of afterdischarge was explained by the attractor associated with repetitive spiking being destroyed. This occurred when ultra-slow negative feedback, such as intracellular sodium accumulation, caused the saddle point and stable limit cycle to collide; in that regard, the active attractor is not truly stable when the slowest dynamics are taken into account. The model also explains other features of paroxysmal symptoms, including temporal summation and refractoriness. PMID:22058273

  1. How do Turkish High School Graduates Use the Wave Theory of Light to Explain Optics Phenomena?

    ERIC Educational Resources Information Center

    Sengoren, S. K.

    2010-01-01

    This research was intended to investigate whether Turkish students who had graduated from high school used the wave theory of light properly in explaining optical phenomena. The survey method was used in this research. The data, which were collected from 175 first year university students in Turkey, were analysed quantitatively and qualitatively.…

  2. Explaining the Intention to Use Technology among University Students: A Structural Equation Modeling Approach

    ERIC Educational Resources Information Center

    Teo, Timothy; Zhou, Mingming

    2014-01-01

    The aim of this study is to examine the factors that an influence higher education students' intention to use technology. Using an extended technology acceptance model as a research framework, a sample of 314 university students were surveyed on their responses to seven constructs hypothesized to explain their intention to use technology.…

  3. Toward Explaining the Transformative Power of Talk about, around, and for Writing

    ERIC Educational Resources Information Center

    Godbee, Beth

    2012-01-01

    This article provides an initial approach for capturing moments of talk about, around, and for writing to explain why writing groups and writing conferences are so often considered "transformative" for the people involved. After describing the widespread and yet disparate transformations so often attributed to collaborative writing talk, I…

  4. Social Community: A Mechanism to Explain the Success of STEM Minority Mentoring Programs

    ERIC Educational Resources Information Center

    Mondisa, Joi-Lynn; McComb, Sara A.

    2015-01-01

    Social community may be a mechanism that explains the success of minority mentoring programs. We define a social community as an environment where like-minded individuals engage in dynamic, multidirectional interactions that facilitate social support. In this conceptual article, we propose a social community model for science, technology,…

  5. Explaining Academic Progress via Combining Concepts of Integration Theory and Rational Choice Theory.

    ERIC Educational Resources Information Center

    Beekhoven, S.; De Jong, U.; Van Hout, H.

    2002-01-01

    Compared elements of rational choice theory and integration theory on the basis of their power to explain variance in academic progress. Asserts that the concepts should be combined, and the distinction between social and academic integration abandoned. Empirical analysis showed that an extended model, comprising both integration and rational…

  6. Eight Models for Explaining States' Total Spending for People with Developmental Disabilities in the United States.

    ERIC Educational Resources Information Center

    Campbell, Edward M.; Fortune, Jon; Heinlein, Ken B.

    This report investigated the financial expenditures of states for services for individuals with developmental disabilities and examined the factors that influenced the level of expenditure. Eight multiple-regression models are presented which explain 70 to 88 percent of the variation in states' total expenditures. In addition to the obvious…

  7. Why Teach Abroad: Two American Teachers Explain Their Motivations and Experiences Teaching in Bulgaria

    ERIC Educational Resources Information Center

    Potash, Betsy; Potash, Brett

    2011-01-01

    A Fulbright poster on the bulletin board, a Search Associates flier in the mailbox, a rumor of something different--everyone has heard about teaching abroad. But is it worth filling out all that paperwork, installing Skype on the family's computers, and learning a new language? In this article, two American teachers explain their motivations and…

  8. Microwave-Mediated Synthesis of Lophine: Developing a Mechanism to Explain a Product

    ERIC Educational Resources Information Center

    Crouch, R. David; Howard, Jessica L.; Zile, Jennifer L.; Barker, Kathryn H.

    2006-01-01

    The microwave-mediated preparation of lophine (2,4,5-triphenylimidazole) is described. This experiment allows for an introduction to the emerging technology of microwave-assisted organic synthesis while providing an opportunity for students to employ the principles of carbonyl chemistry in devising a mechanism to explain the formation of the…

  9. Microwave-Mediated Synthesis of Lophine: Developing a Mechanism to Explain a Product

    ERIC Educational Resources Information Center

    Crouch, R. David; Howard, Jessica L.; Zile, Jennifer L.; Barker, Kathryn H.

    2006-01-01

    The microwave-mediated preparation of lophine (2,4,5-triphenylimidazole) is described. This experiment allows for an introduction to the emerging technology of microwave-assisted organic synthesis while providing an opportunity for students to employ the principles of carbonyl chemistry in devising a mechanism to explain the formation of the…

  10. Why Science? Members of PSR Editorial Board Explain What Drew Them to Science

    ERIC Educational Resources Information Center

    Primary Science Review, 2006

    2006-01-01

    Members of "Primary Science Review" Editorial Board explain what drew them to science. Alan Peacock, "PSR" Editor, emphasises the need to preserve children's sense of wonderment about the world. Robert Collins, a science educator in the Faculty of Education, University of Strathclyde, thinks people are "secret science…

  11. Run-D.M.C.: A Mnemonic Aid for Explaining Mass Transfer in Electrochemical Systems

    ERIC Educational Resources Information Center

    Miles, Deon T.

    2013-01-01

    Electrochemistry is a significant area of analytical chemistry encompassing electrical measurements of chemical systems. The applications associated with electrochemistry appear in many aspects of everyday life: explaining how batteries work, how the human nervous system functions, and how metal corrosion occurs. The most common electrochemical…

  12. Disentangling vegetation diversity from climate–energy and habitat heterogeneity for explaining animal geographic patterns

    USGS Publications Warehouse

    Jimenez-Alfaro, Borja; Chytry, Milan; Mucina, Ladislav; Grace, James B.; Rejmanek, Marcel

    2016-01-01

    Broad-scale animal diversity patterns have been traditionally explained by hypotheses focused on climate–energy and habitat heterogeneity, without considering the direct influence of vegetation structure and composition. However, integrating these factors when considering plant–animal correlates still poses a major challenge because plant communities are controlled by abiotic factors that may, at the same time, influence animal distributions. By testing whether the number and variation of plant community types in Europe explain country-level diversity in six animal groups, we propose a conceptual framework in which vegetation diversity represents a bridge between abiotic factors and animal diversity. We show that vegetation diversity explains variation in animal richness not accounted for by altitudinal range or potential evapotranspiration, being the best predictor for butterflies, beetles, and amphibians. Moreover, the dissimilarity of plant community types explains the highest proportion of variation in animal assemblages across the studied regions, an effect that outperforms the effect of climate and their shared contribution with pure spatial variation. Our results at the country level suggest that vegetation diversity, as estimated from broad-scale classifications of plant communities, may contribute to our understanding of animal richness and may be disentangled, at least to a degree, from climate–energy and abiotic habitat heterogeneity.

  13. Bullying Explains Only Part of LGBTQ-Heterosexual Risk Disparities: Implications for Policy and Practice

    ERIC Educational Resources Information Center

    Robinson, Joseph P.; Espelage, Dorothy L.

    2012-01-01

    Students who identify as lesbian, gay, bisexual, transgender, and questioning (LGBTQ) experience higher rates of victimization by bullying than do their heterosexual-identified peers. In this article, we investigate the extent to which this difference in rates of victimization can explain LGBTQ youths' greater rates of suicidal ideation, suicide…

  14. How Can We Explain Poverty? Case Study of Dee Reveals the Complexities

    ERIC Educational Resources Information Center

    Seccombe, Karen

    2011-01-01

    Many theories have been offered to explain why people are impoverished. This article by Karen Seccombe uses the case study of "Dee," a newly single mother, to explore four of the most common: individualism, social structuralism, the culture of poverty, and fatalism. She concludes that poverty is a highly complex phenomenon, and it is likely that…

  15. Premetastatic milieu explained by TLR4 agonist-mediated homeostatic inflammation.

    PubMed

    Maru, Yoshiro

    2010-03-01

    Accumulating evidence suggests that Toll-like receptor 4 (TLR4), a sensor for danger signals, is expressed not only in immune cells, but also in resident epithelial cells, and appears to participate in tissue homeostasis. To explain the premetastatic microenvironment created by the newly discovered endogenous TLR4 ligands, I propose a hypothesis of homeostatic inflammation that includes the classical danger hypothesis.

  16. What explains the rural-urban gap in infant mortality: household or community characteristics?

    PubMed

    Van de Poel, Ellen; O'Donnell, Owen; Van Doorslaer, Eddy

    2009-11-01

    The rural-urban gap in infant mortality rates is explained by using a new decomposition method that permits identification of the contribution of unobserved heterogeneity at the household and the community level. Using Demographic and Health Survey data for six Francophone countries in Central and West sub-Saharan Africa, we find that differences in the distributions of factors that determine mortality--not differences in their effects--explain almost the entire gap. Higher infant mortality rates in rural areas mainly derive from the rural disadvantage in household characteristics, both observed and unobserved, which explain two-thirds of the gap. Among the observed characteristics, environmental factors--a safe source of drinking water, electricity, and quality of housing materials--are the most important contributors. Community characteristics explain less than one-quarter of the gap, with about two-thirds of this coming from community unobserved heterogeneity and one-third from the existence of a health facility within the community. The effect of disadvantageous environmental conditions--such as limited electricity and water supply--derives both from a lack of community-level infrastructure and from the inability of some households to exploit it when available. Policy needs to operate at both the community and household levels to correct such deficiencies.

  17. Explaining Inference on a Population of Independent Agents Using Bayesian Networks

    ERIC Educational Resources Information Center

    Sutovsky, Peter

    2013-01-01

    The main goal of this research is to design, implement, and evaluate a novel explanation method, the hierarchical explanation method (HEM), for explaining Bayesian network (BN) inference when the network is modeling a population of conditionally independent agents, each of which is modeled as a subnetwork. For example, consider disease-outbreak…

  18. What We Don't Understand, We Explain to Each Other

    ERIC Educational Resources Information Center

    Pines, David

    2015-01-01

    "What we don't understand, we explain to each other" was Robert Oppenheimer's 1948 description of theoretical physics as a profession. Because the phrase connects research, teaching, and learning, it seemed the right approach for the talk I gave to the AAPT [American Association of Physics Teachers] on receiving the 2013 J.D. Jackson…

  19. The Black Professoriate: Explaining the Salary Gap for African-American Female Professors.

    ERIC Educational Resources Information Center

    Guillory, Elizabeth A.

    2001-01-01

    Investigates salary differences between black female faculty and their white male/female and black male counterparts. Results indicate that black women earn less than white and black males but slightly more than white women. Although race/gender differences in faculty earnings exist, they are largely explained by variations in rank, tenure,…

  20. A Socio-Psychophysiological Model for Explaining the Causal Effects of Social Reinforcement Systems.

    ERIC Educational Resources Information Center

    Brown, Edward K.

    The expanded socio-psychophysiological model (SPPM) appears to provide a meaningful paradigm for explaining the psycho-psysiological effects of Social Reinforcement Systems (SRS). This model may be used to assist individuals, and the society, to become more aware of the effects that social practices have on the immediate and long-term actions of…

  1. Cognitive Abilities Explaining Age-Related Changes in Time Perception of Short and Long Durations

    ERIC Educational Resources Information Center

    Zelanti, Pierre S.; Droit-Volet, Sylvie

    2011-01-01

    The current study investigated how the development of cognitive abilities explains the age-related changes in temporal judgment over short and long duration ranges from 0.5 to 30 s. Children (5- and 9-year-olds) as well as adults were given a temporal bisection task with four different duration ranges: a duration range shorter than 1 s, two…

  2. PISA and High-Performing Education Systems: Explaining Singapore's Education Success

    ERIC Educational Resources Information Center

    Deng, Zongyi; Gopinathan, S.

    2016-01-01

    Singapore's remarkable performance in Programme for International Student Assessment (PISA) has placed it among the world's high-performing education systems (HPES). In the literature on HPES, its "secret formula" for education success is explained in terms of teacher quality, school leadership, system characteristics and educational…

  3. Facilitating High School Students' Use of Multiple Representations to Describe and Explain Simple Chemical Reactions

    ERIC Educational Resources Information Center

    Chandrasegaran, A. L.; Treagust, David F.; Mocerino, Mauro

    2011-01-01

    This study involved the evaluation of the efficacy of a planned instructional program to facilitate understanding of the macroscopic, submicroscopic and symbolic representational systems when describing and explaining chemical reactions by sixty-five Grade 9 students in a Singapore secondary school. A two-tier multiple-choice diagnostic instrument…

  4. Explaining Cross-Country Differences in Attitudes towards Immigration in the EU-15

    ERIC Educational Resources Information Center

    Malchow-Moller, Nikolaj; Munch, Jakob Roland; Schroll, Sanne; Skaksen, Jan Rose

    2009-01-01

    In this paper, we use data from the first two rounds of the European Social Survey to analyze the extent to which differences in average attitudes towards immigration across the EU-15 countries may be explained by differences in socioeconomic characteristics and individually perceived consequences of immigration, using an extension of a…

  5. The Search for a Permanent Home: Explaining the Organizational Instability of Air Force Rescue

    DTIC Science & Technology

    2015-06-01

    The Search for a Permanent Home: Explaining the Organizational Instability of Air Force Rescue BY Major Mark Uberuaga A THESIS...SPACE STUDIES AIR UNIVERSITY MAXWELL AIR FORCE BASE, ALABAMA JUNE 2015 DISTRIBUTION A. Approved for public release: distribution...official position of the US Government, Department of Defense, the United States Air Force , or Air University. iv ABOUT THE AUTHOR

  6. A Model of How Different Biology Experts Explain Molecular and Cellular Mechanisms

    ERIC Educational Resources Information Center

    Trujillo, Caleb M.; Anderson, Trevor R.; Pelaez, Nancy J.

    2015-01-01

    Constructing explanations is an essential skill for all science learners. The goal of this project was to model the key components of expert explanation of molecular and cellular mechanisms. As such, we asked: What is an appropriate model of the components of explanation used by biology experts to explain molecular and cellular mechanisms? Do…

  7. PISA and High-Performing Education Systems: Explaining Singapore's Education Success

    ERIC Educational Resources Information Center

    Deng, Zongyi; Gopinathan, S.

    2016-01-01

    Singapore's remarkable performance in Programme for International Student Assessment (PISA) has placed it among the world's high-performing education systems (HPES). In the literature on HPES, its "secret formula" for education success is explained in terms of teacher quality, school leadership, system characteristics and educational…

  8. Semantic Language as a Mechanism Explaining the Association between ADHD Symptoms and Reading and Mathematics Underachievement

    ERIC Educational Resources Information Center

    Gremillion, Monica L.; Martel, Michelle M.

    2012-01-01

    ADHD is associated with academic underachievement, but it remains unclear what mechanism accounts for this association. Semantic language is an underexplored mechanism that provides a developmental explanation for this association. The present study will examine whether semantic language deficits explain the association between ADHD and reading…

  9. Who Gets the App? Explaining Law School Application Volume, 1993 to 1996. LSAC Research Report Series.

    ERIC Educational Resources Information Center

    Longley, Charles

    In recent years there has been a steady decline in the number of applications filed for full-time admission to American Bar Association-approved law schools. This study sought to determine what explains interinstitutional variation in application volume for the years 1993 to 1996. Using multivariate regression analysis, the study tested a…

  10. Combining Self-Explaining with Computer Architecture Diagrams to Enhance the Learning of Assembly Language Programming

    ERIC Educational Resources Information Center

    Hung, Y.-C.

    2012-01-01

    This paper investigates the impact of combining self explaining (SE) with computer architecture diagrams to help novice students learn assembly language programming. Pre- and post-test scores for the experimental and control groups were compared and subjected to covariance (ANCOVA) statistical analysis. Results indicate that the SE-plus-diagram…

  11. Explaining the Difference between PISA 2009 Reading Scores in Finland and Estonia

    ERIC Educational Resources Information Center

    Mikk, Jaan

    2015-01-01

    The aim of the study was to explain the difference between the Programme for International Student Assessment (PISA) 2009 reading results for Finland and Estonia using characteristics of teaching and learning, and characteristics of the overall development of these countries. PISA data were collected via a reading test and student questionnaires…

  12. Children Learning to Explain Daily Celestial Motion: Understanding Astronomy across Moving Frames of Reference

    ERIC Educational Resources Information Center

    Plummer, Julia D.; Wasko, Kyle D.; Slagle, Cynthia

    2011-01-01

    This study investigated elementary students' explanations for the daily patterns of apparent motion of the Sun, Moon, and stars. Third-grade students were chosen for this study because this age level is at the lower end of when many US standards documents suggest students should learn to use the Earth's rotation to explain daily celestial motion.…

  13. Explaining Variability in Retrieval Times for Addition Produced by Students with Mathematical Learning Difficulties

    ERIC Educational Resources Information Center

    Hopkins, Sarah L.; Lawson, Michael J.

    2004-01-01

    Predictors of retrieval times produced by students having difficulty developing a reliance on retrieval for simple addition were discovered. The findings support the notion that separate limitations operate in working memory when retrieval occurs and call into question the use of the term "retrieval deficit" to explain difficulties…

  14. Explaining the Rise in Educational Gradients in Mortality. NBER Working Paper No. 15678

    ERIC Educational Resources Information Center

    Cutler, David M.; Lange, Fabian; Meara, Ellen; Richards, Seth; Ruhm, Christopher J.

    2010-01-01

    The long-standing inverse relationship between education and mortality strengthened substantially later in the 20th century. This paper examines the reasons for this increase. We show that behavioral risk factors are not of primary importance. Smoking has declined more for the better educated, but not enough to explain the trend. Obesity has risen…

  15. Ideas, Institutions, and School Curricula: Explaining Variation between England and France

    ERIC Educational Resources Information Center

    Haus, Leah

    2015-01-01

    This study raises the question of why the French secondary school history curricula introduced in the late 2000s prescribed more extensive coverage of plural histories than did secondary school history curricula for English schools introduced in the same time period. Both countries share similar societal diversity. To explain the variation in…

  16. Disentangling vegetation diversity from climate-energy and habitat heterogeneity for explaining animal geographic patterns.

    PubMed

    Jiménez-Alfaro, Borja; Chytrý, Milan; Mucina, Ladislav; Grace, James B; Rejmánek, Marcel

    2016-03-01

    Broad-scale animal diversity patterns have been traditionally explained by hypotheses focused on climate-energy and habitat heterogeneity, without considering the direct influence of vegetation structure and composition. However, integrating these factors when considering plant-animal correlates still poses a major challenge because plant communities are controlled by abiotic factors that may, at the same time, influence animal distributions. By testing whether the number and variation of plant community types in Europe explain country-level diversity in six animal groups, we propose a conceptual framework in which vegetation diversity represents a bridge between abiotic factors and animal diversity. We show that vegetation diversity explains variation in animal richness not accounted for by altitudinal range or potential evapotranspiration, being the best predictor for butterflies, beetles, and amphibians. Moreover, the dissimilarity of plant community types explains the highest proportion of variation in animal assemblages across the studied regions, an effect that outperforms the effect of climate and their shared contribution with pure spatial variation. Our results at the country level suggest that vegetation diversity, as estimated from broad-scale classifications of plant communities, may contribute to our understanding of animal richness and may be disentangled, at least to a degree, from climate-energy and abiotic habitat heterogeneity.

  17. Can Intertrial Effects of Features and Dimensions Be Explained by a Single Theory?

    ERIC Educational Resources Information Center

    Becker, Stefanie I.

    2008-01-01

    This study investigated feature- and dimension-based intertrial effects in visual search for a pop-out target. The 2 prominent theories explaining intertrial effects, priming of pop-out and dimension weighting, both assume that repeating the target from the previous trial facilitates attention shifts to the target, whereas changing the target…

  18. No Place to Escape: Explaining the Cultural Revolution to American Students

    ERIC Educational Resources Information Center

    Jiang, Ji-li

    2012-01-01

    In this article the author reflects on her visits to American schools to talk about the experiences she describes in "Red Scarf Girl." In her book, she explains picture by picture, story after story how she and her family lived in darkness, how they were brainwashed, and about the concentration of power in China. She stresses that …

  19. The Utility of the UTAUT Model in Explaining Mobile Learning Adoption in Higher Education in Guyana

    ERIC Educational Resources Information Center

    Thomas, Troy Devon; Singh, Lenandlar; Gaffar, Kemuel

    2013-01-01

    In this paper, we compare the utility of modified versions of the unified theory of acceptance and use of technology (UTAUT) model in explaining mobile learning adoption in higher education in a developing country and evaluate the size and direction of the impacts of the UTAUT factors on behavioural intention to adopt mobile learning in higher…

  20. Does Mother's IQ Explain the Association between Birth Weight and Cognitive Ability in Childhood?

    ERIC Educational Resources Information Center

    Deary, Ian J.; Der, Geoff; Shenkin, Susan D.

    2005-01-01

    There is a significant association between birth weight and cognitive test scores in childhood, even among individuals born at term and with normal birth weight. The association is not explained by the child's social background. Here we examine whether mother's cognitive ability accounts for the birth weight-cognitive ability association. We…

  1. Explaining How Political Actors Gain Strategic Positions: Predictors of Centrality in State Reading Policy Issue Networks

    ERIC Educational Resources Information Center

    Young, Tamara V.; Wang, Yuling; Lewis, Wayne D.

    2016-01-01

    Using data from interviews with 111 reading policy actors from California, Connecticut, Michigan, and Utah, this study explains how individuals acquire central positions in issue networks. Regression analyses showed that the greater a policy actor's reputed influence was and the more similar their preferences were to other members in the network,…

  2. Explaining Inference on a Population of Independent Agents Using Bayesian Networks

    ERIC Educational Resources Information Center

    Sutovsky, Peter

    2013-01-01

    The main goal of this research is to design, implement, and evaluate a novel explanation method, the hierarchical explanation method (HEM), for explaining Bayesian network (BN) inference when the network is modeling a population of conditionally independent agents, each of which is modeled as a subnetwork. For example, consider disease-outbreak…

  3. The Positive Illusory Bias: Does It Explain Self-Evaluations in College Students with ADHD?

    ERIC Educational Resources Information Center

    Prevatt, Frances; Proctor, Briley; Best, Lori; Baker, Leigh; Van Walker, Jerry; Taylor, Nicki Wright

    2012-01-01

    Objective: To evaluate whether the positive illusory bias explains the self-evaluations of driving and work behaviors in college students with ADHD. Method: A total of 103 students with ADHD were compared to a sample of 94 students without ADHD. Both groups completed self-reports of their specific driving and work behaviors and then rated their…

  4. The Role of Attitudes about Vaccine Safety, Efficacy, and Value in Explaining Parents' Reported Vaccination Behavior

    ERIC Educational Resources Information Center

    LaVail, Katherine Hart; Kennedy, Allison Michelle

    2013-01-01

    Objectives: To explain vaccine confidence as it related to parents' decisions to vaccinate their children with recommended vaccines, and to develop a confidence measure to efficiently and effectively predict parents' self-reported vaccine behaviors. Method: A sample of parents with at least one child younger than 6 years ("n" = 376) was…

  5. Alternative Multidimensional Models Explaining and Improving Academic Achievement in Latino Students

    ERIC Educational Resources Information Center

    Gonzalez, Virginia; Soltero, Sonia W.

    2011-01-01

    Our objective is to provide two multidimensional models (i.e., contextual-interaction and Ethnic Educator) including sociopolitical, socioeconomic, sociocultural, and sociohistorical factors explaining underachievement in Latinos. First, we critically discuss single-factor theories (i.e., deficit, resistance, social reproduction, cultural…

  6. Explaining the Gap in Charter and Traditional Public School Teacher Turnover Rates

    ERIC Educational Resources Information Center

    Stuit, David A.; Smith, Thomas M.

    2012-01-01

    This study uses national survey data to examine why charter school teachers are more likely to turnover than their traditional public school counterparts. We test whether the turnover gap is explained by different distributions of factors that are empirically and theoretically linked to turnover risk. We find that the turnover rate of charter…

  7. Semantic Language as a Mechanism Explaining the Association between ADHD Symptoms and Reading and Mathematics Underachievement

    ERIC Educational Resources Information Center

    Gremillion, Monica L.; Martel, Michelle M.

    2012-01-01

    ADHD is associated with academic underachievement, but it remains unclear what mechanism accounts for this association. Semantic language is an underexplored mechanism that provides a developmental explanation for this association. The present study will examine whether semantic language deficits explain the association between ADHD and reading…

  8. Why Science? Members of PSR Editorial Board Explain What Drew Them to Science

    ERIC Educational Resources Information Center

    Primary Science Review, 2006

    2006-01-01

    Members of "Primary Science Review" Editorial Board explain what drew them to science. Alan Peacock, "PSR" Editor, emphasises the need to preserve children's sense of wonderment about the world. Robert Collins, a science educator in the Faculty of Education, University of Strathclyde, thinks people are "secret science…

  9. Explaining Metaphors in High-Functioning Autism Spectrum Disorder Children: A Brief Report

    ERIC Educational Resources Information Center

    Melogno, Sergio; D'Ardia, Caterina; Pinto, Maria Antonietta; Levi, Gabriel

    2012-01-01

    This study investigated metaphor comprehension in a group of 24 Italian high-functioning ASD children (mean age: 8.5 y.). Children were administered a test that was composed of "sensorial metaphors", which are understood by normally developing preschoolers, that the children had to verbally explain. Two normally developing control…

  10. Arms Control and Missile Defense: Explaining Success and Failure in U.S.-Russian Cooperation

    DTIC Science & Technology

    2013-09-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited ARMS CONTROL AND...September 2013 3. REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE ARMS CONTROL AND MISSILE DEFENSE: EXPLAINING SUCCESS AND...on its nuclear arsenal and permanent seat on the United Nations Security Council. This research analyzed arms control and ballistic missile defense

  11. Common SNPs explain some of the variation in the personality dimensions of neuroticism and extraversion.

    PubMed

    Vinkhuyzen, A A E; Pedersen, N L; Yang, J; Lee, S H; Magnusson, P K E; Iacono, W G; McGue, M; Madden, P A F; Heath, A C; Luciano, M; Payton, A; Horan, M; Ollier, W; Pendleton, N; Deary, I J; Montgomery, G W; Martin, N G; Visscher, P M; Wray, N R

    2012-04-17

    The personality traits of neuroticism and extraversion are predictive of a number of social and behavioural outcomes and psychiatric disorders. Twin and family studies have reported moderate heritability estimates for both traits. Few associations have been reported between genetic variants and neuroticism/extraversion, but hardly any have been replicated. Moreover, the ones that have been replicated explain only a small proportion of the heritability (<~2%). Using genome-wide single-nucleotide polymorphism (SNP) data from ~12,000 unrelated individuals we estimated the proportion of phenotypic variance explained by variants in linkage disequilibrium with common SNPs as 0.06 (s.e. = 0.03) for neuroticism and 0.12 (s.e. = 0.03) for extraversion. In an additional series of analyses in a family-based sample, we show that while for both traits ~45% of the phenotypic variance can be explained by pedigree data (that is, expected genetic similarity) one third of this can be explained by SNP data (that is, realized genetic similarity). A part of the so-called 'missing heritability' has now been accounted for, but some of the reported heritability is still unexplained. Possible explanations for the remaining missing heritability are that: (i) rare variants that are not captured by common SNPs on current genotype platforms make a major contribution; and/ or (ii) the estimates of narrow sense heritability from twin and family studies are biased upwards, for example, by not properly accounting for nonadditive genetic factors and/or (common) environmental factors.

  12. The Role of Colorism in Explaining African American Females' Suspension Risk

    ERIC Educational Resources Information Center

    Blake, Jamilia J.; Keith, Verna M.; Luo, Wen; Le, Huong; Salter, Phia

    2017-01-01

    African American female students' elevated suspension risk has received national attention. Despite a number of studies documenting racial/ethnic disparities in African American females' school suspension risk, few investigations have attempted to explain why these disparities occur. The purpose of this study was to examine the role of colorism in…

  13. How Can We Explain Poverty? Case Study of Dee Reveals the Complexities

    ERIC Educational Resources Information Center

    Seccombe, Karen

    2011-01-01

    Many theories have been offered to explain why people are impoverished. This article by Karen Seccombe uses the case study of "Dee," a newly single mother, to explore four of the most common: individualism, social structuralism, the culture of poverty, and fatalism. She concludes that poverty is a highly complex phenomenon, and it is likely that…

  14. Explaining Parents' School Involvement: The Role of Ethnicity and Gender in the Netherlands

    ERIC Educational Resources Information Center

    Fleischmann, Fenella; de Haas, Annabel

    2016-01-01

    Ethnic minority parents are often less involved with their children's schooling, and this may hamper their children's academic success, thus contributing to ethnic educational inequality. The authors aim to explain differences in parental involvement, using nationally representative survey data from the Netherlands of parents of primary…

  15. How do Turkish High School Graduates Use the Wave Theory of Light to Explain Optics Phenomena?

    ERIC Educational Resources Information Center

    Sengoren, S. K.

    2010-01-01

    This research was intended to investigate whether Turkish students who had graduated from high school used the wave theory of light properly in explaining optical phenomena. The survey method was used in this research. The data, which were collected from 175 first year university students in Turkey, were analysed quantitatively and qualitatively.…

  16. Metaphors Used by Some Engineering Academics in Australia for Understanding and Explaining Sustainability

    ERIC Educational Resources Information Center

    Carew, Anna L.; Mitchell, Cynthia A.

    2006-01-01

    Metaphors can be powerful teaching and learning tools which may help us to understand novel, complex or abstract concepts using familiar language and thought structures. Academics routinely use metaphors in their university teaching to explain new or difficult ideas to students. In this article the authors argue that tertiary teachers' metaphors…

  17. Can self-representationalism explain away the apparent irreducibility of consciousness?

    PubMed

    McClelland, Tom

    Kriegel's self-representationalist (SR) theory of phenomenal consciousness pursues two projects. The first is to offer a positive account of how conscious experience arises from physical brain processes. The second is to explain why consciousness misleadingly appears to be irreducible to the physical i.e. to 'demystify' consciousness. This paper seeks to determine whether SR succeeds on the second project. Kriegel trades on a distinction between the subjective character and qualitative character of conscious states. Subjective character is the property of being a conscious state at all, while qualitative character determines what it is like to be in that state. Kriegel claims that SR explains why subjective character misleadingly appears irreducible, thereby neutralising the apparent irreducibility of consciousness. I argue that although SR credibly demystifies subjective character, it cannot explain why qualitative character also appears irreducible. I conclude that we should pursue the possibility of a hybrid position that combines SR with an account that does explain the apparent irreducibility of qualitative character.

  18. Changes in variance explained by top SNP windows over generations for three traits in broiler chicken

    PubMed Central

    Fragomeni, Breno de Oliveira; Misztal, Ignacy; Lourenco, Daniela Lino; Aguilar, Ignacio; Okimoto, Ronald; Muir, William M.

    2014-01-01

    The purpose of this study was to determine if the set of genomic regions inferred as accounting for the majority of genetic variation in quantitative traits remain stable over multiple generations of selection. The data set contained phenotypes for five generations of broiler chicken for body weight, breast meat, and leg score. The population consisted of 294,632 animals over five generations and also included genotypes of 41,036 single nucleotide polymorphism (SNP) for 4,866 animals, after quality control. The SNP effects were calculated by a GWAS type analysis using single step genomic BLUP approach for generations 1–3, 2–4, 3–5, and 1–5. Variances were calculated for windows of 20 SNP. The top ten windows for each trait that explained the largest fraction of the genetic variance across generations were examined. Across generations, the top 10 windows explained more than 0.5% but less than 1% of the total variance. Also, the pattern of the windows was not consistent across generations. The windows that explained the greatest variance changed greatly among the combinations of generations, with a few exceptions. In many cases, a window identified as top for one combination, explained less than 0.1% for the other combinations. We conclude that identification of top SNP windows for a population may have little predictive power for genetic selection in the following generations for the traits here evaluated. PMID:25324857

  19. Analysing How Scientists Explain Their Research: A Rubric for Measuring the Effectiveness of Scientific Explanations

    ERIC Educational Resources Information Center

    Sevian, Hannah; Gonsalves, Lisa

    2008-01-01

    The present article presents a rubric we developed for assessing the quality of scientific explanations by science graduate students. The rubric was developed from a qualitative analysis of science graduate students' abilities to explain their own research to an audience of non-scientists. Our intention is that use of the rubric to characterise…

  20. Explaining dietary intake in adolescent girls from disadvantaged secondary schools. A test of Social Cognitive Theory.

    PubMed

    Lubans, David R; Plotnikoff, Ronald C; Morgan, Philip J; Dewar, Deborah; Costigan, Sarah; Collins, Clare E

    2012-04-01

    Much of the research on the determinants of dietary behavior has been guided by Bandura's Social Cognitive Theory (SCT), yet few studies have tested the utility of its proposed structural paths. The aim of this paper was to test the capacity of SCT to explain dietary behaviors in a sample of 357 adolescent girls (13.2±0.5 years) from 12 secondary schools located in low-income communities in New South Wales, Australia. Participants completed validated SCT scales assessing nutrition-related self-efficacy, intention, behavioral strategies, family support, situation, outcome expectations, and outcome expectancies. Participants completed a validated food frequency questionnaire, from which, the percentage of total kilojoules from core-foods, non-core foods and saturated fat were calculated. The theoretical models were tested using structural equation modeling in AMOS. The models explained 48-51% and 13-19% of the variance in intention and dietary behavior, respectively. The models provided an adequate fit to the data, and self-efficacy was positively associated with healthy eating and inversely associated with unhealthy eating. However, the pathway from intention to behavior was not statistically significant in any of the models. While this study has demonstrated the utility of SCT constructs to explain behavior in adolescents girls, the proposed structural pathways were not supported. Further study of the role that implementation intentions play in explaining adolescent girls' dietary behaviors is required. Copyright © 2012 Elsevier Ltd. All rights reserved.