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Sample records for biological hypothesis testing

  1. Bayesian Hypothesis Testing

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, Stephen A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sigeti, David E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-11-15

    These are a set of slides about Bayesian hypothesis testing, where many hypotheses are tested. The conclusions are the following: The value of the Bayes factor obtained when using the median of the posterior marginal is almost the minimum value of the Bayes factor. The value of τ2 which minimizes the Bayes factor is a reasonable choice for this parameter. This allows a likelihood ratio to be computed with is the least favorable to H0.

  2. Testing One Hypothesis Multiple times

    OpenAIRE

    Algeri, Sara; van Dyk, David A.

    2017-01-01

    Hypothesis testing in presence of a nuisance parameter that is only identifiable under the alternative is challenging in part because standard asymptotic results (e.g., Wilks theorem for the generalized likelihood ratio test) do not apply. Several solutions have been proposed in the statistical literature and their practical implementation often reduces the problem into one of Testing One Hypothesis Multiple times (TOHM). Specifically, a fine discretization of the space of the non-identifiabl...

  3. Robust and distributed hypothesis testing

    CERN Document Server

    Gül, Gökhan

    2017-01-01

    This book generalizes and extends the available theory in robust and decentralized hypothesis testing. In particular, it presents a robust test for modeling errors which is independent from the assumptions that a sufficiently large number of samples is available, and that the distance is the KL-divergence. Here, the distance can be chosen from a much general model, which includes the KL-divergence as a very special case. This is then extended by various means. A minimax robust test that is robust against both outliers as well as modeling errors is presented. Minimax robustness properties of the given tests are also explicitly proven for fixed sample size and sequential probability ratio tests. The theory of robust detection is extended to robust estimation and the theory of robust distributed detection is extended to classes of distributions, which are not necessarily stochastically bounded. It is shown that the quantization functions for the decision rules can also be chosen as non-monotone. Finally, the boo...

  4. Testing the museum versus cradle tropical biological diversity hypothesis: phylogeny, diversification, and ancestral biogeographic range evolution of the ants.

    Science.gov (United States)

    Moreau, Corrie S; Bell, Charles D

    2013-08-01

    Ants are one of the most ecologically and numerically dominant group of terrestrial organisms with most species diversity currently found in tropical climates. Several explanations for the disparity of biological diversity in the tropics compared to temperate regions have been proposed including that the tropics may act as a "museum" where older lineages persist through evolutionary time or as a "cradle" where new species continue to be generated. We infer the molecular phylogenetic relationships of 295 ant specimens including members of all 21 extant subfamilies to explore the evolutionary diversification and biogeography of the ants. By constraining the topology and age of the root node while using 45 fossils as minimum constraints, we converge on an age of 139-158 Mya for the modern ants. Further diversification analyses identified 10 periods with a significant change in the tempo of diversification of the ants, although these shifts did not appear to correspond to ancestral biogeographic range shifts. Likelihood-based historical biogeographic reconstructions suggest that the Neotropics were important in early ant diversification (e.g., Cretaceous). This finding coupled with the extremely high-current species diversity suggests that the Neotropics have acted as both a museum and cradle for ant diversity. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

  5. Teaching hypothesis testing: a necessary challenge

    NARCIS (Netherlands)

    Post, Wendy J.; van Duijn, Marijtje A.J.; Makar, Katie; de Sousa, Bruno; Gould, Robert

    The last decades a debate has been going on about the use of hypothesis testing. This has led some teachers to think that confidence intervals and effect sizes need to be taught instead of formal hypothesis testing with p-values. Although we see shortcomings of the use of p-values in statistical

  6. Hypothesis Testing in the Real World

    Science.gov (United States)

    Miller, Jeff

    2017-01-01

    Critics of null hypothesis significance testing suggest that (a) its basic logic is invalid and (b) it addresses a question that is of no interest. In contrast to (a), I argue that the underlying logic of hypothesis testing is actually extremely straightforward and compelling. To substantiate that, I present examples showing that hypothesis…

  7. Hypothesis testing in hydrology: Theory and practice

    Science.gov (United States)

    Kirchner, James; Pfister, Laurent

    2017-04-01

    Well-posed hypothesis tests have spurred major advances in hydrological theory. However, a random sample of recent research papers suggests that in hydrology, as in other fields, hypothesis formulation and testing rarely correspond to the idealized model of the scientific method. Practices such as "p-hacking" or "HARKing" (Hypothesizing After the Results are Known) are major obstacles to more rigorous hypothesis testing in hydrology, along with the well-known problem of confirmation bias - the tendency to value and trust confirmations more than refutations - among both researchers and reviewers. Hypothesis testing is not the only recipe for scientific progress, however: exploratory research, driven by innovations in measurement and observation, has also underlain many key advances. Further improvements in observation and measurement will be vital to both exploratory research and hypothesis testing, and thus to advancing the science of hydrology.

  8. Knowledge dimensions in hypothesis test problems

    Science.gov (United States)

    Krishnan, Saras; Idris, Noraini

    2012-05-01

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

  9. Error probabilities in default Bayesian hypothesis testing

    NARCIS (Netherlands)

    Gu, Xin; Hoijtink, Herbert; Mulder, J,

    2016-01-01

    This paper investigates the classical type I and type II error probabilities of default Bayes factors for a Bayesian t test. Default Bayes factors quantify the relative evidence between the null hypothesis and the unrestricted alternative hypothesis without needing to specify prior distributions for

  10. Statistical hypothesis testing with SAS and R

    CERN Document Server

    Taeger, Dirk

    2014-01-01

    A comprehensive guide to statistical hypothesis testing with examples in SAS and R When analyzing datasets the following questions often arise:Is there a short hand procedure for a statistical test available in SAS or R?If so, how do I use it?If not, how do I program the test myself? This book answers these questions and provides an overview of the most commonstatistical test problems in a comprehensive way, making it easy to find and performan appropriate statistical test. A general summary of statistical test theory is presented, along with a basicdescription for each test, including the

  11. Debates—Hypothesis testing in hydrology: Introduction

    Science.gov (United States)

    Blöschl, Günter

    2017-03-01

    This paper introduces the papers in the "Debates—Hypothesis testing in hydrology" series. The four articles in the series discuss whether and how the process of testing hypotheses leads to progress in hydrology. Repeated experiments with controlled boundary conditions are rarely feasible in hydrology. Research is therefore not easily aligned with the classical scientific method of testing hypotheses. Hypotheses in hydrology are often enshrined in computer models which are tested against observed data. Testability may be limited due to model complexity and data uncertainty. All four articles suggest that hypothesis testing has contributed to progress in hydrology and is needed in the future. However, the procedure is usually not as systematic as the philosophy of science suggests. A greater emphasis on a creative reasoning process on the basis of clues and explorative analyses is therefore needed.

  12. A test of the orthographic recoding hypothesis

    Science.gov (United States)

    Gaygen, Daniel E.

    2003-04-01

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

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

    Science.gov (United States)

    Baker, Gail A.

    1993-01-01

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

  14. Testing competing forms of the Milankovitch hypothesis

    DEFF Research Database (Denmark)

    Kaufmann, Robert K.; Juselius, Katarina

    2016-01-01

    We test competing forms of the Milankovitch hypothesis by estimating the coefficients and diagnostic statistics for a cointegrated vector autoregressive model that includes 10 climate variables and four exogenous variables for solar insolation. The estimates are consistent with the physical...... ice volume and solar insolation. The estimated adjustment dynamics show that solar insolation affects an array of climate variables other than ice volume, each at a unique rate. This implies that previous efforts to test the strong form of the Milankovitch hypothesis by examining the relationship...... mechanisms postulated to drive glacial cycles. They show that the climate variables are driven partly by solar insolation, determining the timing and magnitude of glaciations and terminations, and partly by internal feedback dynamics, pushing the climate variables away from equilibrium. We argue...

  15. Multi-agent sequential hypothesis testing

    KAUST Repository

    Kim, Kwang-Ki K.

    2014-12-15

    This paper considers multi-agent sequential hypothesis testing and presents a framework for strategic learning in sequential games with explicit consideration of both temporal and spatial coordination. The associated Bayes risk functions explicitly incorporate costs of taking private/public measurements, costs of time-difference and disagreement in actions of agents, and costs of false declaration/choices in the sequential hypothesis testing. The corresponding sequential decision processes have well-defined value functions with respect to (a) the belief states for the case of conditional independent private noisy measurements that are also assumed to be independent identically distributed over time, and (b) the information states for the case of correlated private noisy measurements. A sequential investment game of strategic coordination and delay is also discussed as an application of the proposed strategic learning rules.

  16. A default Bayesian hypothesis test for mediation.

    Science.gov (United States)

    Nuijten, Michèle B; Wetzels, Ruud; Matzke, Dora; Dolan, Conor V; Wagenmakers, Eric-Jan

    2015-03-01

    In order to quantify the relationship between multiple variables, researchers often carry out a mediation analysis. In such an analysis, a mediator (e.g., knowledge of a healthy diet) transmits the effect from an independent variable (e.g., classroom instruction on a healthy diet) to a dependent variable (e.g., consumption of fruits and vegetables). Almost all mediation analyses in psychology use frequentist estimation and hypothesis-testing techniques. A recent exception is Yuan and MacKinnon (Psychological Methods, 14, 301-322, 2009), who outlined a Bayesian parameter estimation procedure for mediation analysis. Here we complete the Bayesian alternative to frequentist mediation analysis by specifying a default Bayesian hypothesis test based on the Jeffreys-Zellner-Siow approach. We further extend this default Bayesian test by allowing a comparison to directional or one-sided alternatives, using Markov chain Monte Carlo techniques implemented in JAGS. All Bayesian tests are implemented in the R package BayesMed (Nuijten, Wetzels, Matzke, Dolan, & Wagenmakers, 2014).

  17. Testing the egocentric mirror-rotation hypothesis.

    Science.gov (United States)

    Muelenz, Cornelius; Hecht, Heiko; Gamer, Matthias

    2010-01-01

    Although observers know about the law of reflection, their intuitive understanding of spatial locations in mirrors is often erroneous. Hecht et al. (2005) proposed a two-stage mirror-rotation hypothesis to explain these misconceptions. The hypothesis involves an egocentric bias to the effect that observers behave as if the mirror surface were rotated by about 2 degrees to be more orthogonal than is the case. We test four variants of the hypothesis, which differ depending on whether the virtual world, the mirror, or both are taken to be rotated. We devised an experimental setup that allowed us to distinguish between these variants. Our results confirm that the virtual world--and only the virtual world--is being rotated. Observers had to perform a localization task, using a mirror that was either fronto-parallel or rotated opposite the direction of the predicted effect. We were thus able to compensate for the effect. The positions of objects in mirrors were perceived in accordance with the erroneous conception that the virtual world behind the mirror is slightly rotated and that the reconstruction is based on the non-rotated fronto-parallel mirror. A covert rotation of the mirror by about 2 degrees against the predicted effect was able to compensate for the placement error.

  18. Consumer health information seeking as hypothesis testing.

    Science.gov (United States)

    Keselman, Alla; Browne, Allen C; Kaufman, David R

    2008-01-01

    Despite the proliferation of consumer health sites, lay individuals often experience difficulty finding health information online. The present study attempts to understand users' information seeking difficulties by drawing on a hypothesis testing explanatory framework. It also addresses the role of user competencies and their interaction with internet resources. Twenty participants were interviewed about their understanding of a hypothetical scenario about a family member suffering from stable angina and then searched MedlinePlus consumer health information portal for information on the problem presented in the scenario. Participants' understanding of heart disease was analyzed via semantic analysis. Thematic coding was used to describe information seeking trajectories in terms of three key strategies: verification of the primary hypothesis, narrowing search within the general hypothesis area and bottom-up search. Compared to an expert model, participants' understanding of heart disease involved different key concepts, which were also differently grouped and defined. This understanding provided the framework for search-guiding hypotheses and results interpretation. Incorrect or imprecise domain knowledge led individuals to search for information on irrelevant sites, often seeking out data to confirm their incorrect initial hypotheses. Online search skills enhanced search efficiency, but did not eliminate these difficulties. Regardless of their web experience and general search skills, lay individuals may experience difficulty with health information searches. These difficulties may be related to formulating and evaluating hypotheses that are rooted in their domain knowledge. Informatics can provide support at the levels of health information portals, individual websites, and consumer education tools.

  19. Test of Taylor's Hypothesis with Distributed Temperature

    Science.gov (United States)

    Cheng, Y.; Gentine, P.; Sayde, C.; Tanner, E.; Ochsner, T. E.; Dong, J.

    2016-12-01

    Taylor's hypothesis[Taylor, 1938] assumes that mean wind speed carries the spatial pattern of turbulent motion past a fixed point in a "frozen" way, which has been widely used to relate streamwise wavenumber and angular frequency . Experiments[Fisher, 1964; Tong, 1996] have shown some deviation from Taylor's hypothesis at highly turbulent intensity flows and at high wavenumbers. However, the velocity or scalar measurements have always been fixed at a few spatial points rather than distributed in space. This experiment was designed for the first time to directly compare the time and spatial spectrum of temperature to test Taylor's hypothesis, measuring temperature with high resolution in both time and space by Distributed Temperature Sensing utilizing the attenuation difference of Raman scattering in the optic fiber at the MOISST site Oklahoma. The length of transact is 233 meters along the dominant wind direction. The temperature sampling distance is 0.127m and sampling time frequency is 1 Hz. The heights of the 4 fiber cables parallel to ground are 1m, 1.254m, 1.508m and 1.762m respectively. Also, eddy covariance instrument was set up near the Distributed Temperature Sensing as comparison for temperature data. The temperature spatial spectrum could be obtained with one fixed time point, while the temperature time spectrum could be obtained with one fixed spatial point in the middle of transact. The preliminary results would be presented in the AGU fall meeting. Reference Fisher, M. J., and Davies, P.O.A.L (1964), Correlation measurements in a non-frozen pattern of turbulence, Journal of fluid mechanics, 18(1), 97-116. Taylor, G. I. (1938), The spectrum of turbulence, Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences, 164(919), 476-490. Tong, C. (1996), Taylor's Hypothesis and Two-point Coherence Measurements, Boundary-Layer Meteorology, 81(3), 399-410.

  20. Hypothesis Testing as an Act of Rationality

    Science.gov (United States)

    Nearing, Grey

    2017-04-01

    Statistical hypothesis testing is ad hoc in two ways. First, setting probabilistic rejection criteria is, as Neyman (1957) put it, an act of will rather than an act of rationality. Second, physical theories like conservation laws do not inherently admit probabilistic predictions, and so we must use what are called epistemic bridge principles to connect model predictions with the actual methods of hypothesis testing. In practice, these bridge principles are likelihood functions, error functions, or performance metrics. I propose that the reason we are faced with these problems is because we have historically failed to account for a fundamental component of basic logic - namely the portion of logic that explains how epistemic states evolve in the presence of empirical data. This component of Cox' (1946) calculitic logic is called information theory (Knuth, 2005), and adding information theory our hypothetico-deductive account of science yields straightforward solutions to both of the above problems. This also yields a straightforward method for dealing with Popper's (1963) problem of verisimilitude by facilitating a quantitative approach to measuring process isomorphism. In practice, this involves data assimilation. Finally, information theory allows us to reliably bound measures of epistemic uncertainty, thereby avoiding the problem of Bayesian incoherency under misspecified priors (Grünwald, 2006). I therefore propose solutions to four of the fundamental problems inherent in both hypothetico-deductive and/or Bayesian hypothesis testing. - Neyman (1957) Inductive Behavior as a Basic Concept of Philosophy of Science. - Cox (1946) Probability, Frequency and Reasonable Expectation. - Knuth (2005) Lattice Duality: The Origin of Probability and Entropy. - Grünwald (2006). Bayesian Inconsistency under Misspecification. - Popper (1963) Conjectures and Refutations: The Growth of Scientific Knowledge.

  1. Gaussian Hypothesis Testing and Quantum Illumination.

    Science.gov (United States)

    Wilde, Mark M; Tomamichel, Marco; Lloyd, Seth; Berta, Mario

    2017-09-22

    Quantum hypothesis testing is one of the most basic tasks in quantum information theory and has fundamental links with quantum communication and estimation theory. In this paper, we establish a formula that characterizes the decay rate of the minimal type-II error probability in a quantum hypothesis test of two Gaussian states given a fixed constraint on the type-I error probability. This formula is a direct function of the mean vectors and covariance matrices of the quantum Gaussian states in question. We give an application to quantum illumination, which is the task of determining whether there is a low-reflectivity object embedded in a target region with a bright thermal-noise bath. For the asymmetric-error setting, we find that a quantum illumination transmitter can achieve an error probability exponent stronger than a coherent-state transmitter of the same mean photon number, and furthermore, that it requires far fewer trials to do so. This occurs when the background thermal noise is either low or bright, which means that a quantum advantage is even easier to witness than in the symmetric-error setting because it occurs for a larger range of parameters. Going forward from here, we expect our formula to have applications in settings well beyond those considered in this paper, especially to quantum communication tasks involving quantum Gaussian channels.

  2. Transpiration: A Test of Optimality Hypothesis

    Science.gov (United States)

    Wang, J.; Bras, R. L.; Lerdau, M.; Salvucci, G. D.; Wofsy, S.

    2003-12-01

    The argument is that the fundamental mechanisms behind bare soil evaporation are also responsible for plant transpiration except that stomata affect the exchange of water vapor between the evaporating surface and the atmosphere. It is hypothesized that the system of liquid water in leaf tissues and the water vapor in the atmosphere tries to evolve towards a potential equilibrium as quickly as possible by maximizing transpiration. In the proposed theory, CO2 flux is used as a non-parametric equivalent of stomatal conductance as CO2 and water vapor diffuse in and out of leaves through the same path. It is further assumed that stomatal aperture is directly controlled by guard cell turgor (or leaf water potential). Transpiration is formulated as a function of leaf temperature, leaf water potential/stomatal conductance (or CO2 flux as the surrogate), and sensible heat flux (characterizing transport mechanism) at a given level of radiative energy input. Optimization of transpiration constrained by the energy balance equation leads to vanishing derivatives of transpiration with respect to leaf temperature and CO2 flux. Effect of vapor pressure deficit on transpiration is also investigated. Preliminary tests using field experimental measurements lead to encouraging evidence in support of the hypothesis. It is found that transpiration is fairly insensitive to atmospheric humidity as suggested by several earlier studies.

  3. The discovered preference hypothesis - an empirical test

    DEFF Research Database (Denmark)

    Lundhede, Thomas; Ladenburg, Jacob; Olsen, Søren Bøye

    Using stated preference methods for valuation of non-market goods is known to be vulnerable to a range of biases. Some authors claim that these so-called anomalies in effect render the methods useless for the purpose. However, the Discovered Preference Hypothesis, as put forth by Plott [31], offe...

  4. Chi-square test and its application in hypothesis testing

    Directory of Open Access Journals (Sweden)

    Rakesh Rana

    2015-01-01

    Full Text Available In medical research, there are studies which often collect data on categorical variables that can be summarized as a series of counts. These counts are commonly arranged in a tabular format known as a contingency table. The chi-square test statistic can be used to evaluate whether there is an association between the rows and columns in a contingency table. More specifically, this statistic can be used to determine whether there is any difference between the study groups in the proportions of the risk factor of interest. Chi-square test and the logic of hypothesis testing were developed by Karl Pearson. This article describes in detail what is a chi-square test, on which type of data it is used, the assumptions associated with its application, how to manually calculate it and how to make use of an online calculator for calculating the Chi-square statistics and its associated P-value.

  5. A test of the substitution-habitat hypothesis in amphibians.

    Science.gov (United States)

    Martínez-Abraín, Alejandro; Galán, Pedro

    2017-12-08

    Most examples that support the substitution-habitat hypothesis (human-made habitats act as substitutes of original habitat) deal with birds and mammals. We tested this hypothesis in 14 amphibians by using percentage occupancy as a proxy of habitat quality (i.e., higher occupancy percentages indicate higher quality). We classified water body types as original habitat (no or little human influence) depending on anatomical, behavioral, or physiological adaptations of each amphibian species. Ten species had relatively high probabilities (0.16-0.28) of occurrence in original habitat, moderate probability of occurrence in substitution habitats (0.11-0.14), and low probability of occurrence in refuge habitats (0.05-0.08). Thus, the substitution-habitat hypothesis only partially applies to amphibians because the low occupancy of refuges could be due to the negligible human persecution of this group (indicating good conservation status). However, low occupancy of refuges could also be due to low tolerance of refuge conditions, which could have led to selective extinction or colonization problems due to poor dispersal capabilities. That original habitats had the highest probabilities of occupancy suggests amphibians have a good conservation status in the region. They also appeared highly adaptable to anthropogenic substitution habitats. © 2017 Society for Conservation Biology.

  6. Hypothesis Tests in Complex Wishart Distributions

    Science.gov (United States)

    Frery, Alejandro C.; Cintra, Renato J.; Nascimento, Abraao D. C.

    2011-03-01

    Quantifying the image contrast between different regions is a major step in image processing. Images obtained from coherent illumination processes are inexorably contaminated with speckle noise. Multilook polarimetric synthetic aperture radar (PolSAR) imagery is a prominent example. Statistical image processing based on the complex Wishart distribution represents a successful approach for modelling PolSAR backscatter data from pasture and forest regions. This work introduces statistical tests for image contrast. Such tests are based on the Kullback-Leibler, Bhattacharyya, Hellinger, Rényi, and chi-square distances. Results Monte Carlo experiments separate the Kullback-Leibler distance as the best one. This result was based on empirical test sizes under several situations which include pure and contaminated data. The proposed methodology was applied to real data, obtained by an E-SAR sensor over surroundings of Weßling, Bavaria, Germany.

  7. Hypothesis testing for differentially correlated features.

    Science.gov (United States)

    Sheng, Elisa; Witten, Daniela; Zhou, Xiao-Hua

    2016-10-01

    In a multivariate setting, we consider the task of identifying features whose correlations with the other features differ across conditions. Such correlation shifts may occur independently of mean shifts, or differences in the means of the individual features across conditions. Previous approaches for detecting correlation shifts consider features simultaneously, by computing a correlation-based test statistic for each feature. However, since correlations involve two features, such approaches do not lend themselves to identifying which feature is the culprit. In this article, we instead consider a serial testing approach, by comparing columns of the sample correlation matrix across two conditions, and removing one feature at a time. Our method provides a novel perspective and favorable empirical results compared with competing approaches. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  8. An Exercise for Illustrating the Logic of Hypothesis Testing

    Science.gov (United States)

    Lawton, Leigh

    2009-01-01

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

  9. New methods of testing nonlinear hypothesis using iterative NLLS estimator

    Science.gov (United States)

    Mahaboob, B.; Venkateswarlu, B.; Mokeshrayalu, G.; Balasiddamuni, P.

    2017-11-01

    This research paper discusses the method of testing nonlinear hypothesis using iterative Nonlinear Least Squares (NLLS) estimator. Takeshi Amemiya [1] explained this method. However in the present research paper, a modified Wald test statistic due to Engle, Robert [6] is proposed to test the nonlinear hypothesis using iterative NLLS estimator. An alternative method for testing nonlinear hypothesis using iterative NLLS estimator based on nonlinear hypothesis using iterative NLLS estimator based on nonlinear studentized residuals has been proposed. In this research article an innovative method of testing nonlinear hypothesis using iterative restricted NLLS estimator is derived. Pesaran and Deaton [10] explained the methods of testing nonlinear hypothesis. This paper uses asymptotic properties of nonlinear least squares estimator proposed by Jenrich [8]. The main purpose of this paper is to provide very innovative methods of testing nonlinear hypothesis using iterative NLLS estimator, iterative NLLS estimator based on nonlinear studentized residuals and iterative restricted NLLS estimator. Eakambaram et al. [12] discussed least absolute deviation estimations versus nonlinear regression model with heteroscedastic errors and also they studied the problem of heteroscedasticity with reference to nonlinear regression models with suitable illustration. William Grene [13] examined the interaction effect in nonlinear models disused by Ai and Norton [14] and suggested ways to examine the effects that do not involve statistical testing. Peter [15] provided guidelines for identifying composite hypothesis and addressing the probability of false rejection for multiple hypotheses.

  10. Hypothesis testing in the Maimai Catchments, Westland

    International Nuclear Information System (INIS)

    Stewart, M.K.

    1993-01-01

    Seven experiments were carried out on the Maimai Catchments, Westland, to test assumptions about the nature of unsaturated zone waters flows in this humid environment. Hypotheses tested were: 1) that the deuterium (D) content of base flow water sources in small streams are constant at any given time, 2) that different soil moisture sampling methods give the same D contents, 3) that throughfall has the same D content as rainfall, 4) that saturation overland flow is mainly composed of current event rainfall, 5) that macropores are not connected into pipe networks, 6) that the underlying substrate (Old Man Gravel conglomerate) does not deliver water to the stream during rainfall events, and 7) that different near-stream water sources have the same D contents at a given time. Over 570 samples were collected of which 300 were analysed for deuterium in 1992-1993. This report gives the background, rationale, methods and brief results of the experiments. The results will be integrated with other measurements and written up in one or more papers for journal publication. (author). 18 refs.; 4 figs.; 1 tab

  11. Testing Happiness Hypothesis among the Elderly

    Directory of Open Access Journals (Sweden)

    Rossi Máximo

    2008-08-01

    Full Text Available We use a rich data set that allows us to test different happiness hypotheses employing four methodological approaches. We find that older people in Uruguay have a tendency to report themselves happy when they are married, when they have higher standards of health and when they earn higher levels of income or they consider that their income is suitable for their standard of living. On the contrary, they report lower levels of happiness when they live alone and when their nutrition is insufficient. We also find that education has no clear impact on happiness. We think that our study is a contribution to the study of those factors that can explain happiness among the elderly in Latin American countries. Future work will focus on enhanced empirical analysis and in extending our study to other countries.

  12. Hypothesis Testing of Parameters for Ordinary Linear Circular Regression

    Directory of Open Access Journals (Sweden)

    Abdul Ghapor Hussin

    2006-07-01

    Full Text Available This paper presents the hypothesis testing of parameters for ordinary linear circular regression model assuming the circular random error distributed as von Misses distribution. The main interests are in testing of the intercept and slope parameter of the regression line. As an illustration, this hypothesis testing will be used in analyzing the wind and wave direction data recorded by two different techniques which are HF radar system and anchored wave buoy.

  13. The fetal programming of telomere biology hypothesis: an update

    Science.gov (United States)

    Entringer, Sonja; Buss, Claudia; Wadhwa, Pathik D.

    2018-01-01

    Research on mechanisms underlying fetal programming of health and disease risk has focused primarily on processes that are specific to cell types, organs or phenotypes of interest. However, the observation that developmental conditions concomitantly influence a diverse set of phenotypes, the majority of which are implicated in age-related disorders, raises the possibility that such developmental conditions may additionally exert effects via a common underlying mechanism that involves cellular/molecular ageing–related processes. In this context, we submit that telomere biology represents a process of particular interest in humans because, firstly, this system represents among the most salient antecedent cellular phenotypes for common age-related disorders; secondly, its initial (newborn) setting appears to be particularly important for its long-term effects; and thirdly, its initial setting appears to be plastic and under developmental regulation. We propose that the effects of suboptimal intrauterine conditions on the initial setting of telomere length and telomerase expression/activity capacity may be mediated by the programming actions of stress-related maternal–placental–fetal oxidative, immune, endocrine and metabolic pathways in a manner that may ultimately accelerate cellular dysfunction, ageing and disease susceptibility over the lifespan. This perspectives paper provides an overview of each of the elements underlying this hypothesis, with an emphasis on recent developments, findings and future directions. This article is part of the theme issue ‘Understanding diversity in telomere dynamics’. PMID:29335381

  14. The fetal programming of telomere biology hypothesis: an update.

    Science.gov (United States)

    Entringer, Sonja; de Punder, Karin; Buss, Claudia; Wadhwa, Pathik D

    2018-03-05

    Research on mechanisms underlying fetal programming of health and disease risk has focused primarily on processes that are specific to cell types, organs or phenotypes of interest. However, the observation that developmental conditions concomitantly influence a diverse set of phenotypes, the majority of which are implicated in age-related disorders, raises the possibility that such developmental conditions may additionally exert effects via a common underlying mechanism that involves cellular/molecular ageing-related processes. In this context, we submit that telomere biology represents a process of particular interest in humans because, firstly, this system represents among the most salient antecedent cellular phenotypes for common age-related disorders; secondly, its initial (newborn) setting appears to be particularly important for its long-term effects; and thirdly, its initial setting appears to be plastic and under developmental regulation. We propose that the effects of suboptimal intrauterine conditions on the initial setting of telomere length and telomerase expression/activity capacity may be mediated by the programming actions of stress-related maternal-placental-fetal oxidative, immune, endocrine and metabolic pathways in a manner that may ultimately accelerate cellular dysfunction, ageing and disease susceptibility over the lifespan. This perspectives paper provides an overview of each of the elements underlying this hypothesis, with an emphasis on recent developments, findings and future directions.This article is part of the theme issue 'Understanding diversity in telomere dynamics'. © 2018 The Author(s).

  15. Cross-system log file analysis for hypothesis testing

    NARCIS (Netherlands)

    Glahn, Christian

    2008-01-01

    Glahn, C. (2008). Cross-system log file analysis for hypothesis testing. Presented at Empowering Learners for Lifelong Competence Development: pedagogical, organisational and technological issues. 4th TENCompetence Open Workshop. April, 10, 2008, Madrid, Spain.

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

    Science.gov (United States)

    Wilkinson, Mick

    2013-01-01

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

  17. Biostatistics series module 2: Overview of hypothesis testing

    Directory of Open Access Journals (Sweden)

    Avijit Hazra

    2016-01-01

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

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

    Science.gov (United States)

    Frane, Andrew V.

    2015-01-01

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

  19. Exercise Test Performance Reveals Evidence of the Cardiorespiratory Fitness Hypothesis.

    Science.gov (United States)

    Billinger, Sandra A; Vidoni, Eric D; Morris, Jill K; Thyfault, John P; Burns, Jeffrey M

    2017-04-01

    Positive physiologic and cognitive responses to aerobic exercise have resulted in a proposed cardiorespiratory (CR) fitness hypothesis in which fitness gains drive changes leading to cognitive benefit. The purpose of this study was to directly assess the CR fitness hypothesis. Using data from an aerobic exercise trial, we examined individuals who completed cardiopulmonary and cognitive testing at baseline and 26 weeks. Change in cognitive test performance was not related to CR fitness change (r 2 = .06, p = .06). However, in the subset of individuals who gave excellent effort during exercise testing, change in cognitive test performance was related to CR fitness change (r 2 = .33, p fitness hypothesis and mechanisms by which physiologic adaptation may drive cognitive change.

  20. A large scale test of the gaming-enhancement hypothesis.

    Science.gov (United States)

    Przybylski, Andrew K; Wang, John C

    2016-01-01

    A growing research literature suggests that regular electronic game play and game-based training programs may confer practically significant benefits to cognitive functioning. Most evidence supporting this idea, the gaming-enhancement hypothesis , has been collected in small-scale studies of university students and older adults. This research investigated the hypothesis in a general way with a large sample of 1,847 school-aged children. Our aim was to examine the relations between young people's gaming experiences and an objective test of reasoning performance. Using a Bayesian hypothesis testing approach, evidence for the gaming-enhancement and null hypotheses were compared. Results provided no substantive evidence supporting the idea that having preference for or regularly playing commercially available games was positively associated with reasoning ability. Evidence ranged from equivocal to very strong in support for the null hypothesis over what was predicted. The discussion focuses on the value of Bayesian hypothesis testing for investigating electronic gaming effects, the importance of open science practices, and pre-registered designs to improve the quality of future work.

  1. A large scale test of the gaming-enhancement hypothesis

    Directory of Open Access Journals (Sweden)

    Andrew K. Przybylski

    2016-11-01

    Full Text Available A growing research literature suggests that regular electronic game play and game-based training programs may confer practically significant benefits to cognitive functioning. Most evidence supporting this idea, the gaming-enhancement hypothesis, has been collected in small-scale studies of university students and older adults. This research investigated the hypothesis in a general way with a large sample of 1,847 school-aged children. Our aim was to examine the relations between young people’s gaming experiences and an objective test of reasoning performance. Using a Bayesian hypothesis testing approach, evidence for the gaming-enhancement and null hypotheses were compared. Results provided no substantive evidence supporting the idea that having preference for or regularly playing commercially available games was positively associated with reasoning ability. Evidence ranged from equivocal to very strong in support for the null hypothesis over what was predicted. The discussion focuses on the value of Bayesian hypothesis testing for investigating electronic gaming effects, the importance of open science practices, and pre-registered designs to improve the quality of future work.

  2. Interactive comparison of hypothesis tests for statistical model checking

    NARCIS (Netherlands)

    de Boer, Pieter-Tjerk; Reijsbergen, D.P.; Scheinhardt, Willem R.W.

    2015-01-01

    We present a web-based interactive comparison of hypothesis tests as are used in statistical model checking, providing users and tool developers with more insight into their characteristics. Parameters can be modified easily and their influence is visualized in real time; an integrated simulation

  3. Semiparametric Power Envelopes for Tests of the Unit Root Hypothesis

    DEFF Research Database (Denmark)

    Jansson, Michael

    This paper derives asymptotic power envelopes for tests of the unit root hypothesis in a zero-mean AR(1) model. The power envelopes are derived using the limits of experiments approach and are semiparametric in the sense that the underlying error distribution is treated as an unknown...

  4. A test for diffusional coherency strain hypothesis in the ...

    Indian Academy of Sciences (India)

    boundary in the case of diffusion induced grain boundary migration (DIGM) and liquid film migration (LFM). In the present work, the validity of diffusional coherency strain hypothesis is verified in Mg–Al alloy, which exhibits discontinuous precipitation. Samples were tested with an applied stress simultaneously with disconti-.

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

    Science.gov (United States)

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

    2013-01-01

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

  6. Biological fingerprint of high LET radiation. Brenner hypothesis

    International Nuclear Information System (INIS)

    Kodama, Yoshiaki; Awa, Akio; Nakamura, Nori

    1997-01-01

    Hypothesis by Brenner et al. (1994) that in chromosome aberrations in human peripheral lymphocytes induced by radiation exposure, F value (dicentrics/rings) differs dependently on the LET and can be a biomarker of high LET radiation like neutron and α-ray was reviewed and evaluated as follows. Radiation and chromosome aberrations; in this section, unstable aberrations like dicentric and rings (r) and stable ones like translocation and pericentric inversions were described. F value. Brenner hypothesis. Bauchinger's refutation. F value determined by FISH method; here, FISH is fluorescence in situ hybridization. F value in studies by author's Radiation Effect Research Facility. Frequency of chromosome aberration in A-bomb survivors and ESR (ESR: electron spin resonance). The cause for fluctuation of F values. The Brenner hypothesis could not be supported by studies by author's facility, suggesting that the rate of inter-chromosomal and intra-chromosomal exchange abnormalities can not be distinguishable by the radiation LET. This might be derived from the difference in detection technology of r rather than in LET. (K.H.)

  7. A critique of statistical hypothesis testing in clinical research

    Directory of Open Access Journals (Sweden)

    Somik Raha

    2011-01-01

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

  8. Testing the double-deficit hypothesis in an adult sample.

    Science.gov (United States)

    Miller, Carlin J; Miller, Scott R; Bloom, Juliana S; Jones, Lauren; Lindstrom, William; Craggs, Jason; Garcia-Barrera, Mauricio; Semrud-Clikeman, Margaret; Gilger, Jeffrey W; Hynd, George W

    2006-06-01

    The double-deficit hypothesis of dyslexia posits that reading deficits are more severe in individuals with weaknesses in phonological awareness and rapid naming than in individuals with deficits in only one of these reading composite skills. In this study, the hypothesis was tested in an adult sample as a model of reading achievement. Participants were parents of children referred for evaluation of reading difficulties. Approximately half of all participants reported difficulty learning to read in childhood and a small subset demonstrated ongoing weaknesses in reading. Structural equation modeling results suggest that the double-deficit hypothesis is an accurate model for understanding adult reading achievement. Better reading achievement was associated with better phonological awareness and faster rapid automatized naming in adults. Posthoc analyses indicated that individuals with double deficits had significantly lower reading achievement than individuals with single deficits or no deficits.

  9. SETI in vivo: testing the we-are-them hypothesis

    Science.gov (United States)

    Makukov, Maxim A.; Shcherbak, Vladimir I.

    2018-04-01

    After it was proposed that life on Earth might descend from seeding by an earlier extraterrestrial civilization motivated to secure and spread life, some authors noted that this alternative offers a testable implication: microbial seeds could be intentionally supplied with a durable signature that might be found in extant organisms. In particular, it was suggested that the optimal location for such an artefact is the genetic code, as the least evolving part of cells. However, as the mainstream view goes, this scenario is too speculative and cannot be meaningfully tested because encoding/decoding a signature within the genetic code is something ill-defined, so any retrieval attempt is doomed to guesswork. Here we refresh the seeded-Earth hypothesis in light of recent observations, and discuss the motivation for inserting a signature. We then show that `biological SETI' involves even weaker assumptions than traditional SETI and admits a well-defined methodological framework. After assessing the possibility in terms of molecular and evolutionary biology, we formalize the approach and, adopting the standard guideline of SETI that encoding/decoding should follow from first principles and be convention-free, develop a universal retrieval strategy. Applied to the canonical genetic code, it reveals a non-trivial precision structure of interlocked logical and numerical attributes of systematic character (previously we found these heuristically). To assess this result in view of the initial assumption, we perform statistical, comparison, interdependence and semiotic analyses. Statistical analysis reveals no causal connection of the result to evolutionary models of the genetic code, interdependence analysis precludes overinterpretation, and comparison analysis shows that known variations of the code lack any precision-logic structures, in agreement with these variations being post-LUCA (i.e. post-seeding) evolutionary deviations from the canonical code. Finally, semiotic

  10. Nearly Efficient Likelihood Ratio Tests of the Unit Root Hypothesis

    DEFF Research Database (Denmark)

    Jansson, Michael; Nielsen, Morten Ørregaard

    Seemingly absent from the arsenal of currently available "nearly efficient" testing procedures for the unit root hypothesis, i.e. tests whose local asymptotic power functions are indistinguishable from the Gaussian power envelope, is a test admitting a (quasi-)likelihood ratio interpretation. We...... show that the likelihood ratio unit root test derived in a Gaussian AR(1) model with standard normal innovations is nearly efficient in that model. Moreover, these desirable properties carry over to more complicated models allowing for serially correlated and/or non-Gaussian innovations....

  11. Mechanisms of eyewitness suggestibility: tests of the explanatory role hypothesis.

    Science.gov (United States)

    Rindal, Eric J; Chrobak, Quin M; Zaragoza, Maria S; Weihing, Caitlin A

    2017-10-01

    In a recent paper, Chrobak and Zaragoza (Journal of Experimental Psychology: General, 142(3), 827-844, 2013) proposed the explanatory role hypothesis, which posits that the likelihood of developing false memories for post-event suggestions is a function of the explanatory function the suggestion serves. In support of this hypothesis, they provided evidence that participant-witnesses were especially likely to develop false memories for their forced fabrications when their fabrications helped to explain outcomes they had witnessed. In three experiments, we test the generality of the explanatory role hypothesis as a mechanism of eyewitness suggestibility by assessing whether this hypothesis can predict suggestibility errors in (a) situations where the post-event suggestions are provided by the experimenter (as opposed to fabricated by the participant), and (b) across a variety of memory measures and measures of recollective experience. In support of the explanatory role hypothesis, participants were more likely to subsequently freely report (E1) and recollect the suggestions as part of the witnessed event (E2, source test) when the post-event suggestion helped to provide a causal explanation for a witnessed outcome than when it did not serve this explanatory role. Participants were also less likely to recollect the suggestions as part of the witnessed event (on measures of subjective experience) when their explanatory strength had been reduced by the presence of an alternative explanation that could explain the same outcome (E3, source test + warning). Collectively, the results provide strong evidence that the search for explanatory coherence influences people's tendency to misremember witnessing events that were only suggested to them.

  12. Prospective detection of large prediction errors: a hypothesis testing approach

    International Nuclear Information System (INIS)

    Ruan, Dan

    2010-01-01

    Real-time motion management is important in radiotherapy. In addition to effective monitoring schemes, prediction is required to compensate for system latency, so that treatment can be synchronized with tumor motion. However, it is difficult to predict tumor motion at all times, and it is critical to determine when large prediction errors may occur. Such information can be used to pause the treatment beam or adjust monitoring/prediction schemes. In this study, we propose a hypothesis testing approach for detecting instants corresponding to potentially large prediction errors in real time. We treat the future tumor location as a random variable, and obtain its empirical probability distribution with the kernel density estimation-based method. Under the null hypothesis, the model probability is assumed to be a concentrated Gaussian centered at the prediction output. Under the alternative hypothesis, the model distribution is assumed to be non-informative uniform, which reflects the situation that the future position cannot be inferred reliably. We derive the likelihood ratio test (LRT) for this hypothesis testing problem and show that with the method of moments for estimating the null hypothesis Gaussian parameters, the LRT reduces to a simple test on the empirical variance of the predictive random variable. This conforms to the intuition to expect a (potentially) large prediction error when the estimate is associated with high uncertainty, and to expect an accurate prediction when the uncertainty level is low. We tested the proposed method on patient-derived respiratory traces. The 'ground-truth' prediction error was evaluated by comparing the prediction values with retrospective observations, and the large prediction regions were subsequently delineated by thresholding the prediction errors. The receiver operating characteristic curve was used to describe the performance of the proposed hypothesis testing method. Clinical implication was represented by miss

  13. Nonparametric hypothesis testing for equality of means on the simplex

    OpenAIRE

    Tsagris, Michail; Preston, Simon; Wood, Andrew T. A.

    2016-01-01

    In the context of data that lie on the simplex, we investigate use of empirical and exponential empirical likelihood, and Hotelling and James statistics, to test the null hypothesis of equal population means based on two independent samples. We perform an extensive numerical study using data simulated from various distributions on the simplex. The results, taken together with practical considerations regarding implementation, support the use of bootstrap-calibrated James statis...

  14. A test of the reward-value hypothesis.

    Science.gov (United States)

    Smith, Alexandra E; Dalecki, Stefan J; Crystal, Jonathon D

    2017-03-01

    Rats retain source memory (memory for the origin of information) over a retention interval of at least 1 week, whereas their spatial working memory (radial maze locations) decays within approximately 1 day. We have argued that different forgetting functions dissociate memory systems. However, the two tasks, in our previous work, used different reward values. The source memory task used multiple pellets of a preferred food flavor (chocolate), whereas the spatial working memory task provided access to a single pellet of standard chow-flavored food at each location. Thus, according to the reward-value hypothesis, enhanced performance in the source memory task stems from enhanced encoding/memory of a preferred reward. We tested the reward-value hypothesis by using a standard 8-arm radial maze task to compare spatial working memory accuracy of rats rewarded with either multiple chocolate or chow pellets at each location using a between-subjects design. The reward-value hypothesis predicts superior accuracy for high-valued rewards. We documented equivalent spatial memory accuracy for high- and low-value rewards. Importantly, a 24-h retention interval produced equivalent spatial working memory accuracy for both flavors. These data are inconsistent with the reward-value hypothesis and suggest that reward value does not explain our earlier findings that source memory survives unusually long retention intervals.

  15. Revisiting the Quantum Brain Hypothesis: Toward Quantum (Neuro)biology?

    Science.gov (United States)

    Jedlicka, Peter

    2017-01-01

    The nervous system is a non-linear dynamical complex system with many feedback loops. A conventional wisdom is that in the brain the quantum fluctuations are self-averaging and thus functionally negligible. However, this intuition might be misleading in the case of non-linear complex systems. Because of an extreme sensitivity to initial conditions, in complex systems the microscopic fluctuations may be amplified and thereby affect the system's behavior. In this way quantum dynamics might influence neuronal computations. Accumulating evidence in non-neuronal systems indicates that biological evolution is able to exploit quantum stochasticity. The recent rise of quantum biology as an emerging field at the border between quantum physics and the life sciences suggests that quantum events could play a non-trivial role also in neuronal cells. Direct experimental evidence for this is still missing but future research should address the possibility that quantum events contribute to an extremely high complexity, variability and computational power of neuronal dynamics.

  16. Testing competing forms of the Milankovitch hypothesis: A multivariate approach

    Science.gov (United States)

    Kaufmann, Robert K.; Juselius, Katarina

    2016-02-01

    We test competing forms of the Milankovitch hypothesis by estimating the coefficients and diagnostic statistics for a cointegrated vector autoregressive model that includes 10 climate variables and four exogenous variables for solar insolation. The estimates are consistent with the physical mechanisms postulated to drive glacial cycles. They show that the climate variables are driven partly by solar insolation, determining the timing and magnitude of glaciations and terminations, and partly by internal feedback dynamics, pushing the climate variables away from equilibrium. We argue that the latter is consistent with a weak form of the Milankovitch hypothesis and that it should be restated as follows: internal climate dynamics impose perturbations on glacial cycles that are driven by solar insolation. Our results show that these perturbations are likely caused by slow adjustment between land ice volume and solar insolation. The estimated adjustment dynamics show that solar insolation affects an array of climate variables other than ice volume, each at a unique rate. This implies that previous efforts to test the strong form of the Milankovitch hypothesis by examining the relationship between solar insolation and a single climate variable are likely to suffer from omitted variable bias.

  17. Planned Hypothesis Tests Are Not Necessarily Exempt From Multiplicity Adjustment

    Directory of Open Access Journals (Sweden)

    Andrew V. Frane

    2015-10-01

    Full Text Available Scientific research often involves testing more than one hypothesis at a time, which can inflate the probability that a Type I error (false discovery will occur. To prevent this Type I error inflation, adjustments can be made to the testing procedure that compensate for the number of tests. Yet many researchers believe that such adjustments are inherently unnecessary if the tests were “planned” (i.e., if the hypotheses were specified before the study began. This longstanding misconception continues to be perpetuated in textbooks and continues to be cited in journal articles to justify disregard for Type I error inflation. I critically evaluate this myth and examine its rationales and variations. To emphasize the myth’s prevalence and relevance in current research practice, I provide examples from popular textbooks and from recent literature. I also make recommendations for improving research practice and pedagogy regarding this problem and regarding multiple testing in general.

  18. A test of the domain-specific acculturation strategy hypothesis.

    Science.gov (United States)

    Miller, Matthew J; Yang, Minji; Lim, Robert H; Hui, Kayi; Choi, Na-Yeun; Fan, Xiaoyan; Lin, Li-Ling; Grome, Rebekah E; Farrell, Jerome A; Blackmon, Sha'kema

    2013-01-01

    Acculturation literature has evolved over the past several decades and has highlighted the dynamic ways in which individuals negotiate experiences in multiple cultural contexts. The present study extends this literature by testing M. J. Miller and R. H. Lim's (2010) domain-specific acculturation strategy hypothesis-that individuals might use different acculturation strategies (i.e., assimilated, bicultural, separated, and marginalized strategies; J. W. Berry, 2003) across behavioral and values domains-in 3 independent cluster analyses with Asian American participants. Present findings supported the domain-specific acculturation strategy hypothesis as 67% to 72% of participants from 3 independent samples using different strategies across behavioral and values domains. Consistent with theory, a number of acculturation strategy cluster group differences emerged across generational status, acculturative stress, mental health symptoms, and attitudes toward seeking professional psychological help. Study limitations and future directions for research are discussed.

  19. Hypothesis testing approaches to the exon prediction problem.

    Science.gov (United States)

    Vilardell, Mireia; Sánchez-Pla, Alex

    2006-12-15

    Many gene identification methods assign scores to gene elements prior to their assembly into predicted genes. The scoring system is often based on log-likelihood ratios. These methods usually perform well but it is difficult to interpret how significant a score is. We have developed several tests of significance for the scores: (1) a sum-of-scores test (SST), (2) an intersection-union test (IUT), based on a multiple hypothesis testing interpretation of an exon's score and (3) a meta-analytical approach (MA), which combines several P-values, corresponding to the exon's parts, to yield a global P-value. We performed simulation studies, which show that the MA has better sensitivity and specificity than other methods and is easier to interpret by non-expert users. This is an improvement over other methods and is especially relevant for users who would like to predict incomplete gene sequences.

  20. Alertness and Cognitive Control: Testing the Early Onset Hypothesis.

    Science.gov (United States)

    Schneider, Darryl W

    2017-11-20

    Previous research has revealed a peculiar interaction between alertness and cognitive control in selective-attention tasks: Congruency effects are larger on alert trials (on which an alerting cue is presented briefly in advance of the imperative stimulus) than on no-alert trials, despite shorter response times (RTs) on alert trials. One explanation for this finding is the early onset hypothesis, which is based on the assumptions that increased alertness shortens stimulus-encoding time and that cognitive control involves gradually focusing attention during a trial. The author tested the hypothesis in 3 experiments by manipulating alertness and stimulus quality (which were intended to shorten and lengthen stimulus-encoding time, respectively) in an arrow-based flanker task involving congruent and incongruent stimuli. Replicating past findings, the alerting manipulation led to shorter RTs but larger congruency effects on alert trials than on no-alert trials. The stimulus-quality manipulation led to longer RTs and larger congruency effects for degraded stimuli than for intact stimuli. These results provide mixed support for the early onset hypothesis, but the author discusses how data and theory might be reconciled if stimulus quality affects stimulus-encoding time and the rate of evidence accumulation in the decision process. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  1. Water Pollution Detection Based on Hypothesis Testing in Sensor Networks

    Directory of Open Access Journals (Sweden)

    Xu Luo

    2017-01-01

    Full Text Available Water pollution detection is of great importance in water conservation. In this paper, the water pollution detection problems of the network and of the node in sensor networks are discussed. The detection problems in both cases of the distribution of the monitoring noise being normal and nonnormal are considered. The pollution detection problems are analyzed based on hypothesis testing theory firstly; then, the specific detection algorithms are given. Finally, two implementation examples are given to illustrate how the proposed detection methods are used in the water pollution detection in sensor networks and prove the effectiveness of the proposed detection methods.

  2. Segmentation by Large Scale Hypothesis Testing - Segmentation as Outlier Detection

    DEFF Research Database (Denmark)

    Darkner, Sune; Dahl, Anders Lindbjerg; Larsen, Rasmus

    2010-01-01

    We propose a novel and efficient way of performing local image segmentation. For many applications a threshold of pixel intensities is sufficient but determine the appropriate threshold value can be difficult. In cases with large global intensity variation the threshold value has to be adapted...... locally. We propose a method based on large scale hypothesis testing with a consistent method for selecting an appropriate threshold for the given data. By estimating the background distribution we characterize the segment of interest as a set of outliers with a certain probability based on the estimated...

  3. A hypothesis on the biological origins and social evolution of music and dance

    Directory of Open Access Journals (Sweden)

    Tianyan eWang

    2015-02-01

    Full Text Available The origins of music and musical emotions is still an enigma, here I propose a comprehensive hypothesis on the origins and evolution of music, dance and speech from a biological and sociological perspective. I suggest that every pitch interval between neighboring notes in music represents corresponding movement pattern through interpreting the Doppler effect of sound, which not only provides a possible explanation to the transposition invariance of music, but also integrates music and dance into a common form—rhythmic movements. Accordingly, investigating the origins of music poses the question: why do humans appreciate rhythmic movements? I suggest that human appreciation of rhythmic movements and rhythmic events developed from the natural selection of organisms adapting to the internal and external rhythmic environments. The perception and production of, as well as synchronization with external and internal rhythms are so vital for an organism’s survival and reproduction, that animals have a rhythm-related reward and emotion (RRRE system. The RRRE system enables the appreciation of rhythmic movements and events, and is integral to the origination of music, dance and speech. The first type of rewards and emotions (rhythm-related rewards and emotions, RRREs are evoked by music and dance, and have biological and social functions, which in turn, promote the evolution of music, dance and speech. These functions also evoke a second type of rewards and emotions, which I name society-related rewards and emotions (SRREs. The neural circuits of RRREs and SRREs develop in species formation and personal growth, with congenital and acquired characteristics, respectively, namely music is the combination of nature and culture. This hypothesis provides probable selection pressures and outlines the evolution of music, dance and speech. The links between the Doppler effect and the RRREs and SRREs can be empirically tested, making the current hypothesis

  4. A hypothesis on the biological origins and social evolution of music and dance.

    Science.gov (United States)

    Wang, Tianyan

    2015-01-01

    The origins of music and musical emotions is still an enigma, here I propose a comprehensive hypothesis on the origins and evolution of music, dance, and speech from a biological and sociological perspective. I suggest that every pitch interval between neighboring notes in music represents corresponding movement pattern through interpreting the Doppler effect of sound, which not only provides a possible explanation for the transposition invariance of music, but also integrates music and dance into a common form-rhythmic movements. Accordingly, investigating the origins of music poses the question: why do humans appreciate rhythmic movements? I suggest that human appreciation of rhythmic movements and rhythmic events developed from the natural selection of organisms adapting to the internal and external rhythmic environments. The perception and production of, as well as synchronization with external and internal rhythms are so vital for an organism's survival and reproduction, that animals have a rhythm-related reward and emotion (RRRE) system. The RRRE system enables the appreciation of rhythmic movements and events, and is integral to the origination of music, dance and speech. The first type of rewards and emotions (rhythm-related rewards and emotions, RRREs) are evoked by music and dance, and have biological and social functions, which in turn, promote the evolution of music, dance and speech. These functions also evoke a second type of rewards and emotions, which I name society-related rewards and emotions (SRREs). The neural circuits of RRREs and SRREs develop in species formation and personal growth, with congenital and acquired characteristics, respectively, namely music is the combination of nature and culture. This hypothesis provides probable selection pressures and outlines the evolution of music, dance, and speech. The links between the Doppler effect and the RRREs and SRREs can be empirically tested, making the current hypothesis scientifically

  5. A hypothesis on the biological origins and social evolution of music and dance

    Science.gov (United States)

    Wang, Tianyan

    2015-01-01

    The origins of music and musical emotions is still an enigma, here I propose a comprehensive hypothesis on the origins and evolution of music, dance, and speech from a biological and sociological perspective. I suggest that every pitch interval between neighboring notes in music represents corresponding movement pattern through interpreting the Doppler effect of sound, which not only provides a possible explanation for the transposition invariance of music, but also integrates music and dance into a common form—rhythmic movements. Accordingly, investigating the origins of music poses the question: why do humans appreciate rhythmic movements? I suggest that human appreciation of rhythmic movements and rhythmic events developed from the natural selection of organisms adapting to the internal and external rhythmic environments. The perception and production of, as well as synchronization with external and internal rhythms are so vital for an organism's survival and reproduction, that animals have a rhythm-related reward and emotion (RRRE) system. The RRRE system enables the appreciation of rhythmic movements and events, and is integral to the origination of music, dance and speech. The first type of rewards and emotions (rhythm-related rewards and emotions, RRREs) are evoked by music and dance, and have biological and social functions, which in turn, promote the evolution of music, dance and speech. These functions also evoke a second type of rewards and emotions, which I name society-related rewards and emotions (SRREs). The neural circuits of RRREs and SRREs develop in species formation and personal growth, with congenital and acquired characteristics, respectively, namely music is the combination of nature and culture. This hypothesis provides probable selection pressures and outlines the evolution of music, dance, and speech. The links between the Doppler effect and the RRREs and SRREs can be empirically tested, making the current hypothesis scientifically

  6. Immigration, political trust, and Brexit - Testing an aversion amplification hypothesis.

    Science.gov (United States)

    Abrams, Dominic; Travaglino, Giovanni A

    2018-04-01

    A few weeks prior to the EU referendum (23rd June 2016) two broadly representative samples of the electorate were drawn in Kent (the south-east of England, N = 1,001) and Scotland (N = 1,088) for online surveys that measured their trust in politicians, concerns about acceptable levels of immigration, threat from immigration, European identification, and voting intention. We tested an aversion amplification hypothesis that the impact of immigration concerns on threat and identification would be amplified when political trust was low. We hypothesized that the effect of aversion amplification on voting intentions would be mediated first by perceived threat from immigration, and then by (dis) identification with Europe. Results in both samples were consistent with this hypothesis and suggest that voters were most likely to reject the political status quo (choose Brexit) when concerns that immigration levels were too high were combined with a low level of trust in politicians. © 2018 The Authors. British Journal of Social Psychology published by John Wiley & Sons Ltd on behalf of British Psychological Society.

  7. Testing for Marshall-Lerner hypothesis: A panel approach

    Science.gov (United States)

    Azizan, Nur Najwa; Sek, Siok Kun

    2014-12-01

    The relationship between real exchange rate and trade balances are documented in many theories. One of the theories is the so-called Marshall-Lerner condition. In this study, we seek to test for the validity of Marshall-Lerner hypothesis, i.e. to reveal if the depreciation of real exchange rate leads to the improvement in trade balances. We focus our study in ASEAN-5 countries and their main trade partners of U.S., Japan and China. The dynamic panel data of pooled mean group (PMG) approach is used to detect the Marshall-Lerner hypothesis among ASEAN-5, between ASEAN-5 and U.S., between ASEAN-5 and Japan and between ASEAN-5 and China respectively. The estimation is based on the autoregressive Distributed Lag or ARDL model for the period of 1970-2012. The paper concludes that Marshal Lerner theory does not hold in bilateral trades in four groups of countries. The trade balances of ASEAN5 are mainly determined by the domestic income level and foreign production cost.

  8. A Highest Order Hypothesis Compatibility Test for Monocular SLAM

    Directory of Open Access Journals (Sweden)

    Edmundo Guerra

    2013-08-01

    Full Text Available Simultaneous Location and Mapping (SLAM is a key problem to solve in order to build truly autonomous mobile robots. SLAM with a unique camera, or monocular SLAM, is probably one of the most complex SLAM variants, based entirely on a bearing-only sensor working over six DOF. The monocular SLAM method developed in this work is based on the Delayed Inverse-Depth (DI-D Feature Initialization, with the contribution of a new data association batch validation technique, the Highest Order Hypothesis Compatibility Test, HOHCT. The Delayed Inverse-Depth technique is used to initialize new features in the system and defines a single hypothesis for the initial depth of features with the use of a stochastic technique of triangulation. The introduced HOHCT method is based on the evaluation of statistically compatible hypotheses and a search algorithm designed to exploit the strengths of the Delayed Inverse-Depth technique to achieve good performance results. This work presents the HOHCT with a detailed formulation of the monocular DI-D SLAM problem. The performance of the proposed HOHCT is validated with experimental results, in both indoor and outdoor environments, while its costs are compared with other popular approaches.

  9. cit: hypothesis testing software for mediation analysis in genomic applications.

    Science.gov (United States)

    Millstein, Joshua; Chen, Gary K; Breton, Carrie V

    2016-08-01

    The challenges of successfully applying causal inference methods include: (i) satisfying underlying assumptions, (ii) limitations in data/models accommodated by the software and (iii) low power of common multiple testing approaches. The causal inference test (CIT) is based on hypothesis testing rather than estimation, allowing the testable assumptions to be evaluated in the determination of statistical significance. A user-friendly software package provides P-values and optionally permutation-based FDR estimates (q-values) for potential mediators. It can handle single and multiple binary and continuous instrumental variables, binary or continuous outcome variables and adjustment covariates. Also, the permutation-based FDR option provides a non-parametric implementation. Simulation studies demonstrate the validity of the cit package and show a substantial advantage of permutation-based FDR over other common multiple testing strategies. The cit open-source R package is freely available from the CRAN website (https://cran.r-project.org/web/packages/cit/index.html) with embedded C ++ code that utilizes the GNU Scientific Library, also freely available (http://www.gnu.org/software/gsl/). joshua.millstein@usc.edu Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  10. Persistent Confusions about Hypothesis Testing in the Social Sciences

    Directory of Open Access Journals (Sweden)

    Christopher Thron

    2015-05-01

    Full Text Available This paper analyzes common confusions involving basic concepts in statistical hypothesis testing. One-third of the social science statistics textbooks examined in the study contained false statements about significance level and/or p-value. We infer that a large proportion of social scientists are being miseducated about these concepts. We analyze the causes of these persistent misunderstandings, and conclude that the conventional terminology is prone to abuse because it does not clearly represent the conditional nature of probabilities and events involved. We argue that modifications in terminology, as well as the explicit introduction of conditional probability concepts and notation into the statistics curriculum in the social sciences, are necessary to prevent the persistence of these errors.

  11. Graphic tests of Easterlin's hypothesis: science or art?

    Science.gov (United States)

    Rutten, A; Higgs, R

    1984-01-01

    Richard Easterlin believes that the postwar fertility cycle is uniquely consistent with the hypothesis of his relative income model of fertility, yet a closer examination of his evidence shows that the case for the relative income explanation is much weaker than initially appears. Easterlin finds the postwar baby boom a transparent event. Couples who entered the labor market in the postwar period have very low material aspirations. Having grown up during the Great Depression and World War II, they were content with a modest level of living. Their labor market experience was very good. Tight restrictions on immigration kept aliens from coming in to fill the gap. Thus the members of his generation occupied an unprecedented position. They could easily meet and even exceed their expectations. This high level of relative income meant that they could have more of everything they wanted, including children. For the children born during the baby boom, all this was reversed, and hence the needs of the baby bust were sown. To test this hypothesis, Easterlin compared the movements of relative income and fertility over the postwar years using a graph. 4 published versions of the graph are presented. The graph shows that relative income and fertility did move together over the cycle, apparently very closely. Easterlin's measure of fertility is the total fertility rate (TFR). There is no such direct measure of relative income. Easterlin develops 2 proxies based on changing economic conditions believed to shape the level of material aspirations. His preferred measure, labeled R or income in his graph, relates the income experience of young couples in the years previous to marriage to that of their parents in the years before the young people left home. Because of the available data limit construction of this index to the years after 1956, another measure, labeled Re or employment in Easterlin's graphs, is constructed for the pre-1956 period. This measure relates the average of

  12. Role of stable isotopes in life--testing isotopic resonance hypothesis.

    Science.gov (United States)

    Zubarev, Roman A

    2011-04-01

    Stable isotopes of most important biological elements, such as C, H, N and O, affect living organisms. In rapidly growing species, deuterium and to a lesser extent other heavy isotopes reduce the growth rate. At least for deuterium it is known that its depletion also negatively impacts the speed of biological processes. As a rule, living organisms "resist" changes in their isotopic environment, preferring natural isotopic abundances. This preference could be due to evolutionary optimization; an additional effect could be due to the presence of the "isotopic resonance". The isotopic resonance phenomenon has been linked to the choice of earliest amino acids, and thus affected the evolution of genetic code. To test the isotopic resonance hypothesis, literature data were analyzed against quantitative and qualitative predictions of the hypothesis. Four studies provided five independent datasets, each in very good quantitative agreement with the predictions. Thus, the isotopic resonance hypothesis is no longer simply plausible; it can now be deemed likely. Additional testing is needed, however, before full acceptance of this hypothesis. Copyright © 2011 Beijing Genomics Institute. Published by Elsevier Ltd. All rights reserved.

  13. The Gateway Hypothesis of substance abuse: developmental, biological and societal perspectives.

    Science.gov (United States)

    Kandel, Denise; Kandel, Eric

    2015-02-01

    The Gateway Hypothesis describes how tobacco or alcohol use precedes marijuana and other illicit drug use. We review the epidemiological data, explore the underlying molecular mechanisms in mice and discuss the societal implications of the hypothesis, including the use of e-cigarettes by young people. Our mouse model identifies biological processes underlying the hypothesis, showing that nicotine is a gateway drug that exerts a priming effect on cocaine through increased global acetylation in the striatum. ©2014 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

  14. A Blind Test of the Younger Dryas Impact Hypothesis.

    Directory of Open Access Journals (Sweden)

    Vance Holliday

    Full Text Available The Younger Dryas Impact Hypothesis (YDIH states that North America was devastated by some sort of extraterrestrial event ~12,800 calendar years before present. Two fundamental questions persist in the debate over the YDIH: Can the results of analyses for purported impact indicators be reproduced? And are the indicators unique to the lower YD boundary (YDB, i.e., ~12.8k cal yrs BP? A test reported here presents the results of analyses that address these questions. Two different labs analyzed identical splits of samples collected at, above, and below the ~12.8ka zone at the Lubbock Lake archaeological site (LL in northwest Texas. Both labs reported similar variation in levels of magnetic micrograins (>300 mg/kg >12.8ka and <11.5ka, but <150 mg/kg 12.8ka to 11.5ka. Analysis for magnetic microspheres in one split, reported elsewhere, produced very low to nonexistent levels throughout the section. In the other split, reported here, the levels of magnetic microspherules and nanodiamonds are low or nonexistent at, below, and above the YDB with the notable exception of a sample <11,500 cal years old. In that sample the claimed impact proxies were recovered at abundances two to four orders of magnitude above that from the other samples. Reproducibility of at least some analyses are problematic. In particular, no standard criteria exist for identification of magnetic spheres. Moreover, the purported impact proxies are not unique to the YDB.

  15. Statistical sampling and hypothesis testing in orthopaedic research.

    Science.gov (United States)

    Bernstein, Joseph; McGuire, Kevin; Freedman, Kevin B

    2003-08-01

    The purpose of the current article was to review the process of hypothesis testing and statistical sampling and empower readers to critically appraise the literature. When the p value of a study lies above the alpha threshold, the results are said to be not statistically significant. It is possible, however, that real differences do exist, but the study was insufficiently powerful to detect them. In that case, the conclusion that two groups are equivalent is wrong. The probability of this mistake, the Type II error, is given by the beta statistic. The complement of beta, or 1-beta, representing the chance of avoiding a Type II error, is termed the statistical power of the study. We previously examined the statistical power and sample size in all of the studies published in 1997 in the American and British volumes of the Journal of Bone and Joint Surgery, and in Clinical Orthopaedics and Related Research. In the journals examined, only 3% of studies had adequate statistical power to detect a small effect size in this sample. In addition, a study examining only randomized control trials in these journals showed that none of 25 randomized control trials had adequate statistical power to detect a small effect size. However, beta, or power, is less well understood. Because of this, researchers and readers should be aware of the need to address issues of statistical power before a study begins and be cautious of studies that conclude that no difference exists between groups.

  16. A global test of the pollination syndrome hypothesis.

    Science.gov (United States)

    Ollerton, Jeff; Alarcón, Ruben; Waser, Nickolas M; Price, Mary V; Watts, Stella; Cranmer, Louise; Hingston, Andrew; Peter, Craig I; Rotenberry, John

    2009-06-01

    'Pollination syndromes' are suites of phenotypic traits hypothesized to reflect convergent adaptations of flowers for pollination by specific types of animals. They were first developed in the 1870s and honed during the mid 20th Century. In spite of this long history and their central role in organizing research on plant-pollinator interactions, the pollination syndromes have rarely been subjected to test. The syndromes were tested here by asking whether they successfully capture patterns of covariance of floral traits and predict the most common pollinators of flowers. Flowers in six communities from three continents were scored for expression of floral traits used in published descriptions of the pollination syndromes, and simultaneously the pollinators of as many species as possible were characterized. Ordination of flowers in a multivariate 'phenotype space' defined by the syndromes showed that almost no plant species fall within the discrete syndrome clusters. Furthermore, in approximately two-thirds of plant species, the most common pollinator could not be successfully predicted by assuming that each plant species belongs to the syndrome closest to it in phenotype space. The pollination syndrome hypothesis as usually articulated does not successfully describe the diversity of floral phenotypes or predict the pollinators of most plant species. Caution is suggested when using pollination syndromes for organizing floral diversity, or for inferring agents of floral adaptation. A fresh look at how traits of flowers and pollinators relate to visitation and pollen transfer is recommended, in order to determine whether axes can be identified that describe floral functional diversity more successfully than the traditional syndromes.

  17. The sequential megafaunal collapse hypothesis: Testing with existing data

    Science.gov (United States)

    DeMaster, Douglas P.; Trites, Andrew W.; Clapham, Phillip; Mizroch, Sally; Wade, Paul; Small, Robert J.; Hoef, Jay Ver

    2006-02-01

    Springer et al. [Springer, A.M., Estes, J.A., van Vliet, G.B., Williams, T.M., Doak, D.F., Danner, E.M., Forney, K.A., Pfister, B., 2003. Sequential megafaunal collapse in the North Pacific Ocean: an ongoing legacy of industrial whaling? Proceedings of the National Academy of Sciences 100 (21), 12,223-12,228] hypothesized that great whales were an important prey resource for killer whales, and that the removal of fin and sperm whales by commercial whaling in the region of the Bering Sea/Aleutian Islands (BSAI) in the late 1960s and 1970s led to cascading trophic interactions that caused the sequential decline of populations of harbor seal, northern fur seal, Steller sea lion and northern sea otter. This hypothesis, referred to as the Sequential Megafaunal Collapse (SMC), has stirred considerable interest because of its implication for ecosystem-based management. The SMC has the following assumptions: (1) fin whales and sperm whales were important as prey species in the Bering Sea; (2) the biomass of all large whale species (i.e., North Pacific right, fin, humpback, gray, sperm, minke and bowhead whales) was in decline in the Bering Sea in the 1960s and early 1970s; and (3) pinniped declines in the 1970s and 1980s were sequential. We concluded that the available data are not consistent with the first two assumptions of the SMC. Statistical tests of the timing of the declines do not support the assumption that pinniped declines were sequential. We propose two alternative hypotheses for the declines that are more consistent with the available data. While it is plausible, from energetic arguments, for predation by killer whales to have been an important factor in the declines of one or more of the three populations of pinnipeds and the sea otter population in the BSAI region over the last 30 years, we hypothesize that the declines in pinniped populations in the BSAI can best be understood by invoking a multiple factor hypothesis that includes both bottom-up forcing (as

  18. Structuring and extracting knowledge for the support of hypothesis generation in molecular biology

    NARCIS (Netherlands)

    Roos, M.; Marshall, M.S.; Gibson, A.P.; Schuemie, M.; Meij, E.; Katrenko, S.; van Hage, W.R.; Krommydas, K.; Adriaans, P.W.

    2009-01-01

    Background: Hypothesis generation in molecular and cellular biology is an empirical process in which knowledge derived from prior experiments is distilled into a comprehensible model. The requirement of automated support is exemplified by the difficulty of considering all relevant facts that are

  19. The Human Release Hypothesis for biological invasions: human activity as a determinant of the abundance of invasive plant species.

    Science.gov (United States)

    Zimmermann, Heike; Brandt, Patric; Fischer, Joern; Welk, Erik; von Wehrden, Henrik

    2014-01-01

    Research on biological invasions has increased rapidly over the past 30 years, generating numerous explanations of how species become invasive. While the mechanisms of invasive species establishment are well studied, the mechanisms driving abundance patterns (i.e. patterns of population density and population size) remain poorly understood. It is assumed that invasive species typically have higher abundances in their new environments than in their native ranges, and patterns of invasive species abundance differ between invaded regions. To explain differences in invasive species abundance, we propose the Human Release Hypothesis. In parallel to the established Enemy Release Hypothesis, this hypothesis states that the differences in abundance of invasive species are found between regions because population expansion is reduced in some regions through continuous land management and associated cutting of the invasive species. The Human Release Hypothesis does not negate other important drivers of species invasions, but rather should be considered as a potentially important complementary mechanism. We illustrate the hypothesis via a case study on an invasive rose species, and hypothesize which locations globally may be most likely to support high abundances of invasive species. We propose that more extensive empirical work on the Human Release Hypothesis could be useful to test its general applicability.

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

    Science.gov (United States)

    Liu, Tung; Stone, Courtenay C.

    1999-01-01

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

  1. Counselor Hypothesis Testing Strategies: The Role of Initial Impressions and Self-Schema.

    Science.gov (United States)

    Strohmer, Douglas C.; Chiodo, Anthony L.

    1984-01-01

    Presents two experiments concerning confirmatory bias in the way counselors collect data to test their hypotheses. Counselors were asked either to develop their own clinical hypothesis or were given a hypothesis to test. Confirmatory bias in hypothesis testing was not supported in either experiment. (JAC)

  2. Personal Hypothesis Testing: The Role of Consistency and Self-Schema.

    Science.gov (United States)

    Strohmer, Douglas C.; And Others

    1988-01-01

    Studied how individuals test hypotheses about themselves. Examined extent to which Snyder's bias toward confirmation persists when negative or nonconsistent personal hypothesis is tested. Found negativity or positivity did not affect hypothesis testing directly, though hypothesis consistency did. Found cognitive schematic variable (vulnerability…

  3. A shift from significance test to hypothesis test through power analysis in medical research

    Directory of Open Access Journals (Sweden)

    Singh Girish

    2006-01-01

    Full Text Available Medical research literature until recently, exhibited substantial dominance of the Fisher′s significance test approach of statistical inference concentrating more on probability of type I error over Neyman-Pearson′s hypothesis test considering both probability of type I and II error. Fisher′s approach dichotomises results into significant or not significant results with a P value. The Neyman-Pearson′s approach talks of acceptance or rejection of null hypothesis. Based on the same theory these two approaches deal with same objective and conclude in their own way. The advancement in computing techniques and availability of statistical software have resulted in increasing application of power calculations in medical research and thereby reporting the result of significance tests in the light of power of the test also. Significance test approach, when it incorporates power analysis contains the essence of hypothesis test approach. It may be safely argued that rising application of power analysis in medical research may have initiated a shift from Fisher′s significance test to Neyman-Pearson′s hypothesis test procedure.

  4. Variability: A Pernicious Hypothesis.

    Science.gov (United States)

    Noddings, Nel

    1992-01-01

    The hypothesis of greater male variability in test results is discussed in its historical context, and reasons feminists have objected to the hypothesis are considered. The hypothesis acquires political importance if it is considered that variability results from biological, rather than cultural, differences. (SLD)

  5. A further test of the inverted-U hypothesis relating achievement anxiety and academic test performance.

    Science.gov (United States)

    Munz, S C; Costello, C T; Korabik, K

    1975-01-01

    The assumption that the inverted-U hypothesis, which shows performance as a function of activation level, mediates the relationship between achievement anxiety and academic test performance was tested by comparing Achievement Anxiety Test scores of 75 male and female college students with a self-report measure of activation taken prior to a classroom examination. Results supported the predicted relationship between achievement anxiety reaction type and academic performance (rho less than .05), but only partially supported the inverted-U hypothesis posited to account for this relationship. Results were further interpreted as suggesting that examinees experience two general types of arousal in the testing situationōne type that enhances performance and one that impedes performance. Further implications of the results were discussed.

  6. The influence of symbolic literacy on memory: testing Plato's hypothesis.

    Science.gov (United States)

    Eskritt, M; Lee, K; Donald, M

    2001-03-01

    The present study examined the influence of the production of external symbols on memory strategies. Plato hypothesized that dependency on writing as an external memory store would be deterimental to memory. Three experiments were conducted to explore this hypothesis. Participants played Concentration, a memory game where players must find matching pairs of cards placed face down in an array. Participants were allowed to make notes to aid their performance under some experimental conditions, while under other conditions they could not. In Experiments 1 and 2, the unexpected removal of participants' notes revealed that the performance benefit was due to notes acting as a form of external memory storage, rather than as an aid to encoding information in memory. Experiment 3 qualified these findings by demonstrating that the identity of each card was retained in memory, while the location of each card tended to be stored in the participants' external notations. These data suggest a modified interpretation of Plato's hypothesis in that symbolic literacy may change how we remember information. Rather than storing all information in memory, we only have to retain the information necessary to use the much larger storage capacity of the external system. Thus, the introduction of external symbols allows for a change in how memory is adaptively distributed.

  7. Testing the reproductive groundplan hypothesis in ants (Hymenoptera: Formicidae).

    Science.gov (United States)

    Pamminger, Tobias; Hughes, William O H

    2017-01-01

    The evolution of complex societies with obligate reproductive division of labor represents one of the major transitions in evolution. In such societies, functionally sterile individuals (workers) perform many of fitness-relevant behaviors including allomaternal ones, without getting any direct fitness benefits. The question of how such worker division of labor has evolved remains controversial. The reproductive groundplan hypothesis (RGPH) offers a powerful proximate explanation for this evolutionary leap. The RGPH argues that the conserved genetic and endocrinological networks regulating fitness-relevant behavior (e g. foraging and brood care) in their solitary ancestors have become decoupled from actual reproduction in the worker caste and now generate worker behavioral phenotypes. However, the empirical support for this hypothesis remains limited to a handful of species making its general validity uncertain. In this study, we combine data from the literature with targeted sampling of key species and apply phylogenetically controlled comparative analysis to investigate if the key prediction of the RGPH, namely an association between allomaternal behavior and an allomaternal physiological state holds in the largest and most species-rich clade of social insects, the ants. Our findings clearly support the RPGH as a general framework to understand the evolution of the worker caste and shed light on one of the major transition in evolutionary history. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

  8. Data-driven smooth tests when the hypothesis Is composite

    NARCIS (Netherlands)

    Kallenberg, W.C.M.; Ledwina, Teresa

    1997-01-01

    In recent years several authors have recommended smooth tests for testing goodness of fit. However, the number of components in the smooth test statistic should be chosen well; otherwise, considerable loss of power may occur. Schwarz's selection rule provides one such good choice. Earlier results on

  9. Parameter Estimation And Hypothesis Testing In A Two Epoch Dam ...

    African Journals Online (AJOL)

    Also computed along with the least square solution and statistical testing were the minimum detectable Bias (MDB) and the Bias to Noise Ratio (BNR). All tests and adjustments were carried out using MOVE 3 software along with the LEICA SKI Pro 2.1. From the results of the tests, only observation to Rover station RF 8 ...

  10. How the environment shapes animal signals: a test of the acoustic adaptation hypothesis in frogs.

    Science.gov (United States)

    Goutte, S; Dubois, A; Howard, S D; Márquez, R; Rowley, J J L; Dehling, J M; Grandcolas, P; Xiong, R C; Legendre, F

    2018-01-01

    Long-distance acoustic signals are widely used in animal communication systems and, in many cases, are essential for reproduction. The acoustic adaptation hypothesis (AAH) implies that acoustic signals should be selected for further transmission and better content integrity under the acoustic constraints of the habitat in which they are produced. In this study, we test predictions derived from the AAH in frogs. Specifically, we focus on the difference between torrent frogs and frogs calling in less noisy habitats. Torrents produce sounds that can mask frog vocalizations and constitute a major acoustic constraint on call evolution. We combine data collected in the field, material from scientific collections and the literature for a total of 79 primarily Asian species, of the families Ranidae, Rhacophoridae, Dicroglossidae and Microhylidae. Using phylogenetic comparative methods and including morphological and environmental potential confounding factors, we investigate putatively adaptive call features in torrent frogs. We use broad habitat categories as well as fine-scale habitat measurements and test their correlation with six call characteristics. We find mixed support for the AAH. Spectral features of torrent frog calls are different from those of frogs calling in other habitats and are related to ambient noise levels, as predicted by the AAH. However, temporal call features do not seem to be shaped by the frogs' calling habitats. Our results underline both the complexity of call evolution and the need to consider multiple factors when investigating this issue. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

  11. Testing Kuznets’ Hypothesis for Russian Regions: Trends and Interpretations

    Directory of Open Access Journals (Sweden)

    James R. Alm

    2016-06-01

    Full Text Available The paper established a number of "stylized facts", one of which is a confirmation of the S. Kuznets’ hypothesis of the nonlinear dependence between the degree of inequality in income distribution and welfare economic systems on the example of a group of Russian regions for the period 2002–2012. It is shown that, for a given sample, the welfare and economic growth factors amplify their influence on inequality in income distribution in the post-crisis period. The monotonous growth of income inequality which was observed before the crisis of 2008 is slowing in the process of raising the per capita gross regional product (GRP during the post-crisis period, and for the foreseeable future, in some regions, its direction can be reversed, while maintaining a trend of socio-economic development. Despite the persistence over time of a convex nature of S. Kuznets’ curve for Russian regional data, its parameters changed during the reporting 2002–2012 period. The maximum point of the curve shifts to the left, its convexity increases. These facts indicate that the income inequality growth of the Russian regions’ as a result of growth of per capita GRP is slowing. For some regions in the post-crisis period, the income inequality does not grow with the growth of per capita GRP, or it even reduces. This fact can be attributed to the implementation of the Russian federal socially oriented projects and programs in recent years. The results can be used for the development of regional economic policy in order to regulate the level of income distribution inequality in the regions of Russia.

  12. Hypothesis Testing of Population Percentiles via the Wald Test with Bootstrap Variance Estimates

    Science.gov (United States)

    Johnson, William D.; Romer, Jacob E.

    2016-01-01

    Testing the equality of percentiles (quantiles) between populations is an effective method for robust, nonparametric comparison, especially when the distributions are asymmetric or irregularly shaped. Unlike global nonparametric tests for homogeneity such as the Kolmogorv-Smirnov test, testing the equality of a set of percentiles (i.e., a percentile profile) yields an estimate of the location and extent of the differences between the populations along the entire domain. The Wald test using bootstrap estimates of variance of the order statistics provides a unified method for hypothesis testing of functions of the population percentiles. Simulation studies are conducted to show performance of the method under various scenarios and to give suggestions on its use. Several examples are given to illustrate some useful applications to real data. PMID:27034909

  13. Introduction to Permutation and Resampling-Based Hypothesis Tests

    Science.gov (United States)

    LaFleur, Bonnie J.; Greevy, Robert A.

    2009-01-01

    A resampling-based method of inference--permutation tests--is often used when distributional assumptions are questionable or unmet. Not only are these methods useful for obvious departures from parametric assumptions (e.g., normality) and small sample sizes, but they are also more robust than their parametric counterparts in the presences of…

  14. ePlant: Visualizing and Exploring Multiple Levels of Data for Hypothesis Generation in Plant Biology.

    Science.gov (United States)

    Waese, Jamie; Fan, Jim; Pasha, Asher; Yu, Hans; Fucile, Geoffrey; Shi, Ruian; Cumming, Matthew; Kelley, Lawrence A; Sternberg, Michael J; Krishnakumar, Vivek; Ferlanti, Erik; Miller, Jason; Town, Chris; Stuerzlinger, Wolfgang; Provart, Nicholas J

    2017-08-01

    A big challenge in current systems biology research arises when different types of data must be accessed from separate sources and visualized using separate tools. The high cognitive load required to navigate such a workflow is detrimental to hypothesis generation. Accordingly, there is a need for a robust research platform that incorporates all data and provides integrated search, analysis, and visualization features through a single portal. Here, we present ePlant (http://bar.utoronto.ca/eplant), a visual analytic tool for exploring multiple levels of Arabidopsis thaliana data through a zoomable user interface. ePlant connects to several publicly available web services to download genome, proteome, interactome, transcriptome, and 3D molecular structure data for one or more genes or gene products of interest. Data are displayed with a set of visualization tools that are presented using a conceptual hierarchy from big to small, and many of the tools combine information from more than one data type. We describe the development of ePlant in this article and present several examples illustrating its integrative features for hypothesis generation. We also describe the process of deploying ePlant as an "app" on Araport. Building on readily available web services, the code for ePlant is freely available for any other biological species research. © 2017 American Society of Plant Biologists. All rights reserved.

  15. Some consequences of using the Horsfall-Barratt scale for hypothesis testing

    Science.gov (United States)

    Comparing treatment effects by hypothesis testing is a common practice in plant pathology. Nearest percent estimates (NPEs) of disease severity were compared to Horsfall-Barratt (H-B) scale data to explore whether there was an effect of assessment method on hypothesis testing. A simulation model ba...

  16. What Are Null Hypotheses? The Reasoning Linking Scientific and Statistical Hypothesis Testing

    Science.gov (United States)

    Lawson, Anton E.

    2008-01-01

    We should dispense with use of the confusing term "null hypothesis" in educational research reports. To explain why the term should be dropped, the nature of, and relationship between, scientific and statistical hypothesis testing is clarified by explication of (a) the scientific reasoning used by Gregor Mendel in testing specific…

  17. The biological waste product formation in the light of the membrane hypothesis of aging.

    Science.gov (United States)

    Zs-Nagy, Imre

    2002-01-01

    The membrane hypothesis of aging (MHA) explains the biological waste product (lipofuscin) formation as a disbalance between the rates of protein synthesis and damage, as well as of elimination of the damaged components. Although, this concept has not been refuted on the basis of any experimental evidence, it has neither been widely accepted. During the last decade the general interest has turned toward the molecular genetics so intensely, that research aimed at clarifying cell biological mechanisms became so to say hibernated. Nowadays it is being recognized more and more that after the complete description of the human genetic code, attention has to be dedicated again to the cellular mechanisms explaining the function of the gene products (proteins). In this context, our experimental findings described during the recent years may become again the subject of interest. We have shown that the in vivo inhibition of the lysosomal thiol-proteinase functions by sublethal doses of leupeptin in young, adult and old mice results in a considerable increase (about 30%) of the immobile fraction of membrane proteins in hepatocyte plasma membrane, meanwhile the lateral diffusion constant of the still mobile membrane proteins increased. These observations were interpreted as signs of a general slowing down of protein turnover in the plasma membrane, just by inhibiting the elimination mechanisms in the lysosomes. This paper will discuss the theoretical conclusions and significance of these findings for the biological waste product formation, as a basic cell biological function.

  18. Nonparametric Bayes Classification and Hypothesis Testing on Manifolds

    Science.gov (United States)

    Bhattacharya, Abhishek; Dunson, David

    2012-01-01

    Our first focus is prediction of a categorical response variable using features that lie on a general manifold. For example, the manifold may correspond to the surface of a hypersphere. We propose a general kernel mixture model for the joint distribution of the response and predictors, with the kernel expressed in product form and dependence induced through the unknown mixing measure. We provide simple sufficient conditions for large support and weak and strong posterior consistency in estimating both the joint distribution of the response and predictors and the conditional distribution of the response. Focusing on a Dirichlet process prior for the mixing measure, these conditions hold using von Mises-Fisher kernels when the manifold is the unit hypersphere. In this case, Bayesian methods are developed for efficient posterior computation using slice sampling. Next we develop Bayesian nonparametric methods for testing whether there is a difference in distributions between groups of observations on the manifold having unknown densities. We prove consistency of the Bayes factor and develop efficient computational methods for its calculation. The proposed classification and testing methods are evaluated using simulation examples and applied to spherical data applications. PMID:22754028

  19. Testing a double AGN hypothesis for Mrk 273

    Science.gov (United States)

    Iwasawa, K.; U, V.; Mazzarella, J. M.; Medling, A. M.; Sanders, D. B.; Evans, A. S.

    2018-04-01

    The ultra-luminous infrared galaxy (ULIRG) Mrk 273 contains two infrared nuclei, N and SW, separated by 1 arcsecond. A Chandra observation has identified the SW nucleus as an absorbed X-ray source with NH 4 × 1023 cm-2 but also hinted at the possible presence of a Compton-thick AGN in the N nucleus, where a black hole of 109 M⊙ is inferred from the ionized gas kinematics. The intrinsic X-ray spectral slope recently measured by NuSTAR is unusually hard (Γ 1.3) for a Seyfert nucleus, for which we seek an alternative explanation. We hypothesize a strongly absorbed X-ray source in N, of which X-ray emission rises steeply above 10 keV, in addition to the known X-ray source in SW, and test it against the NuSTAR data, assuming the standard spectral slope (Γ = 1.9). This double X-ray source model gives a good explanation of the hard continuum spectrum, deep Fe K absorption edge, and strong Fe K line observed in this ULIRG, without invoking the unusual spectral slope required for a single source interpretation. The putative X-ray source in N is found to be absorbed by NH = 1.4+0.7-0.4 × 1024 cm-2. The estimated 2-10 keV luminosity of the N source is 1.3 × 1043 erg s-1, about a factor of 2 larger than that of SW during the NuSTAR observation. Uncorrelated variability above and below 10 keV between the Suzaku and NuSTAR observations appears to support the double source interpretation. Variability in spectral hardness and Fe K line flux between the previous X-ray observations is also consistent with this picture.

  20. Testing the Late-Veneer hypothesis with selenium isotopes

    Science.gov (United States)

    Labidi, J.; Koenig, S.; Bennett, N.; Kurzawa, T.; Aierken, E.; Shahar, A.; Schoenberg, R.

    2016-12-01

    Selenium (Se) is a siderophile element displaying an excess abundance in Earth's mantle compared to experimental predictions [1], which may be attributed to the Late-Veneer. As Se is also volatile, testing the late-veneer addition of Se can constrain the origin of other volatile elements on Earth. Here we combine high-precision Se isotope measurements of metal-silicate partitioning experiments and chondrites to assess whether planetary differentiation could leave a measurable Se isotopic signature on planetary mantles. We performed Se isotopic measurements of 5 metal-silicate partitioning experiments and 20 chondrites of all major classes. Experiments were conducted at 1 GPa and 1650 C for 1 to 4 hours using the piston-cylinder apparatus at Carnegie's Geophysical Laboratory. After wet chemistry, data were obtained on a ThermoFisher Scientific™ NeptunePlus MC-ICP-MS at the University of Tübingen with a 74Se/77Se double spike technique. δ82/76Se values are given relative to NIST SRM-3149 and the external reproducibility calculated from duplicate meteorite analyses is ≤ 0.1‰ (2 s.d.). Chondrites vary over a 0.8‰ range of δ82/76Se values. CIs and CMs show evidence for heavier 82Se/76Se ratios, likely due to mixing processes in the proto-planetary nebula. When these isotopically heavier meteorites are excluded, remaining chondrites have δ82/76Se values varying over a 0.3‰ range, within uncertainty of previous results [2]. We suggest that these chondrites may be used to estimate a δ82/76Se value of bulk planets. At the conditions of our experiments, the partition coefficients for Se log Dmetal-silicate range from 0.7±0.1 to 1.9±0.1, consistent with previous work [1]. A small but resolvable Se isotopic fractionation was observed: 82Se/76Se ratios were enriched by ≤ 0.5‰ in the silicates relative to the metals. Thus, given current uncertainties for Se isotopic measurements, marginal differences between planetary mantles and chondrites may be resolved

  1. Different meaning of the p-value in exploratory and confirmatory hypothesis testing

    DEFF Research Database (Denmark)

    Gerke, Oke; Høilund-Carlsen, Poul Flemming; Vach, Werner

    2011-01-01

    The outcome of clinical studies is often reduced to the statistical significance of results by indicating a p-value below the 5% significance level. Hypothesis testing and, through that, the p-value is commonly used, but their meaning is frequently misinterpreted in clinical research. The concept...... of hypothesis testing is explained and some pitfalls including those of multiple testing are given. The conceptual difference between exploratory and confirmatory hypothesis testing is discussed, and a better use of p-values, which includes presenting p-values with two or three decimals, is suggested....

  2. Molecular biology, epidemiology, and the demise of the linear no-threshold (LNT) hypothesis.

    Science.gov (United States)

    Pollycove, M; Feinendegen, L E

    1999-01-01

    The prime concern of radiation protection policy since 1959 has been protecting DNA from damage. The 1995 NCRP Report 121 on collective dose states that since no human data provides direct support for the linear no threshold hypothesis (LNT), and some studies provide quantitative data that, with statistical significance, contradict LNT, ultimately, confidence in LNT is based on the biophysical concept that the passage of a single charged particle could cause damage to DNA that would result in cancer. Current understanding of the basic molecular biologic mechanisms involved and recent data are examined before presenting several statistically significant epidemiologic studies that contradict the LNT hypothesis. Over eons of time a complex biosystem evolved to control the DNA alterations (oxidative adducts) produced by about 10(10) free radicals/cell/d derived from 2-3% of all metabolized oxygen. Antioxidant prevention, enzymatic repair of DNA damage, and removal of persistent DNA alterations by apoptosis, differentiation, necrosis, and the immune system, sequentially reduce DNA damage from about 10(6) DNA alterations/cell/d to about 1 mutation/cell/d. These mutations accumulate in stem cells during a lifetime with progressive DNA damage-control impairment associated with aging and malignant growth. A comparatively negligible number of mutations, an average of about 10(-7) mutations/cell/d, is produced by low LET radiation background of 0.1 cGy/y. The remarkable efficiency of this biosystem is increased by the adaptive responses to low-dose ionizing radiation. Each of the sequential functions that prevent, repair, and remove DNA damage are adaptively stimulated by low-dose ionizing radiation in contrast to their impairment by high-dose radiation. The biologic effect of radiation is not determined by the number of mutations it creates, but by its effect on the biosystem that controls the relentless enormous burden of oxidative DNA damage. At low doses, radiation

  3. The Interaction between Language and Culture: A Test of the Cultural Accommodation Hypothesis in Seven Countries.

    Science.gov (United States)

    Harzing, Anne-Wil; Maznevski, Martha

    2002-01-01

    Investigates the cultural accommodation hypothesis in questionnaire-based research: Do respondents adjust their responses in a way that reflects the cultural values associated with the language of the questionnaire. A test of this hypothesis with a sample of university students in seven countries indicates that cultural accommodation plays an…

  4. Picture-Perfect Is Not Perfect for Metamemory: Testing the Perceptual Fluency Hypothesis with Degraded Images

    Science.gov (United States)

    Besken, Miri

    2016-01-01

    The perceptual fluency hypothesis claims that items that are easy to perceive at encoding induce an illusion that they will be easier to remember, despite the finding that perception does not generally affect recall. The current set of studies tested the predictions of the perceptual fluency hypothesis with a picture generation manipulation.…

  5. A Test of the Curvilinear Hypothesis with FACES II and III.

    Science.gov (United States)

    Pratt, David M.; Hansen, James C.

    1987-01-01

    Olson's Circumplex Model hypothesizes that cohesiveness and adaptability dimensions measured on Family Adaptability and Cohesion Evaluation Scales (FACES) have a curvilinear relationship with family functioning. Study testing curvilinear hypothesis indicated that FACES II and III did not adequately operationalize curvilinear hypothesis. Findings…

  6. A checklist to facilitate objective hypothesis testing in social psychology research.

    Science.gov (United States)

    Washburn, Anthony N; Morgan, G Scott; Skitka, Linda J

    2015-01-01

    Social psychology is not a very politically diverse area of inquiry, something that could negatively affect the objectivity of social psychological theory and research, as Duarte et al. argue in the target article. This commentary offers a number of checks to help researchers uncover possible biases and identify when they are engaging in hypothesis confirmation and advocacy instead of hypothesis testing.

  7. Adolescents' Body Image Trajectories: A Further Test of the Self-Equilibrium Hypothesis

    Science.gov (United States)

    Morin, Alexandre J. S.; Maïano, Christophe; Scalas, L. Francesca; Janosz, Michel; Litalien, David

    2017-01-01

    The self-equilibrium hypothesis underlines the importance of having a strong core self, which is defined as a high and developmentally stable self-concept. This study tested this hypothesis in relation to body image (BI) trajectories in a sample of 1,006 adolescents (M[subscript age] = 12.6, including 541 males and 465 females) across a 4-year…

  8. Balassa-Samuelson Hypothesis: A Test Of Turkish Economy By ARDL Bound Testing Approach

    Directory of Open Access Journals (Sweden)

    Utku ALTUNÖZ

    2014-06-01

    Full Text Available Balassa-Samuelson effect is a popular theme at last years that introduced by Bèla Balassa (1964 and Paul Samuelson (1964. This concept, suggests that a differentiation at international level between the relative rates of productivity of the tradable and non tradable sectors may cause structural and permanent deviations from the purchasing power parity. In this essay, related variables are tested through Balassa-Samuelson Effect in terms of Turkey-European Economy. The choice of econometric technique used to estimate the model was important because the regressors in the model appeared to be a mixture of I(0 and I(1 processes. Thus ARDL bounds testing approaches to co integration analysis in estimating the long-run determinants of the real exchange rates. Given the dataset and econometric techniques used, the results do not support the B-S hypothesis.

  9. Men’s Perception of Raped Women: Test of the Sexually Transmitted Disease Hypothesis and the Cuckoldry Hypothesis

    Directory of Open Access Journals (Sweden)

    Prokop Pavol

    2016-06-01

    Full Text Available Rape is a recurrent adaptive problem of female humans and females of a number of non-human animals. Rape has various physiological and reproductive costs to the victim. The costs of rape are furthermore exaggerated by social rejection and blaming of a victim, particularly by men. The negative perception of raped women by men has received little attention from an evolutionary perspective. Across two independent studies, we investigated whether the risk of sexually transmitted diseases (the STD hypothesis, Hypothesis 1 or paternity uncertainty (the cuckoldry hypothesis, Hypothesis 2 influence the negative perception of raped women by men. Raped women received lower attractiveness score than non-raped women, especially in long-term mate attractiveness score. The perceived attractiveness of raped women was not influenced by the presence of experimentally manipulated STD cues on faces of putative rapists. Women raped by three men received lower attractiveness score than women raped by one man. These results provide stronger support for the cuckoldry hypothesis (Hypothesis 2 than for the STD hypothesis (Hypothesis 1. Single men perceived raped women as more attractive than men in a committed relationship (Hypothesis 3, suggesting that the mating opportunities mediate men’s perception of victims of rape. Overall, our results suggest that the risk of cuckoldry underlie the negative perception of victims of rape by men rather than the fear of disease transmission.

  10. Promoting Student Inquiry Using "Zea Mays" (Corn) Cultivars for Hypothesis-Driven Experimentation in a Majors Introductory Biology Course

    Science.gov (United States)

    Blair, Amy C.; Peters, Brenda J.; Bendixen, Conrad W.

    2014-01-01

    The AAAS Vision and Change report (2011) recommends incorporating student research experiences into the biology curriculum at the undergraduate level. This article describes, in detail, how "Zea mays" (corn) cultivars were used as a model for a hypothesis-driven short-term research project in an introductory biology course at a small…

  11. GSMA: Gene Set Matrix Analysis, An Automated Method for Rapid Hypothesis Testing of Gene Expression Data

    Directory of Open Access Journals (Sweden)

    Chris Cheadle

    2007-01-01

    Full Text Available Background: Microarray technology has become highly valuable for identifying complex global changes in gene expression patterns. The assignment of functional information to these complex patterns remains a challenging task in effectively interpreting data and correlating results from across experiments, projects and laboratories. Methods which allow the rapid and robust evaluation of multiple functional hypotheses increase the power of individual researchers to data mine gene expression data more efficiently.Results: We have developed (gene set matrix analysis GSMA as a useful method for the rapid testing of group-wise up- or downregulation of gene expression simultaneously for multiple lists of genes (gene sets against entire distributions of gene expression changes (datasets for single or multiple experiments. The utility of GSMA lies in its flexibility to rapidly poll gene sets related by known biological function or as designated solely by the end-user against large numbers of datasets simultaneously.Conclusions: GSMA provides a simple and straightforward method for hypothesis testing in which genes are tested by groups across multiple datasets for patterns of expression enrichment.

  12. Bayesian hypothesis testing for psychologists: a tutorial on the Savage-Dickey method.

    Science.gov (United States)

    Wagenmakers, Eric-Jan; Lodewyckx, Tom; Kuriyal, Himanshu; Grasman, Raoul

    2010-05-01

    In the field of cognitive psychology, the p-value hypothesis test has established a stranglehold on statistical reporting. This is unfortunate, as the p-value provides at best a rough estimate of the evidence that the data provide for the presence of an experimental effect. An alternative and arguably more appropriate measure of evidence is conveyed by a Bayesian hypothesis test, which prefers the model with the highest average likelihood. One of the main problems with this Bayesian hypothesis test, however, is that it often requires relatively sophisticated numerical methods for its computation. Here we draw attention to the Savage-Dickey density ratio method, a method that can be used to compute the result of a Bayesian hypothesis test for nested models and under certain plausible restrictions on the parameter priors. Practical examples demonstrate the method's validity, generality, and flexibility. Copyright 2009 Elsevier Inc. All rights reserved.

  13. Microbes in Mascara: Hypothesis-Driven Research in a Nonmajor Biology Lab †

    Science.gov (United States)

    Burleson, Kathryn M.; Martinez-Vaz, Betsy M.

    2011-01-01

    In this laboratory exercise, students were taught concepts of microbiology and scientific process through an everyday activity — cosmetic use. The students’ goals for the lab were to develop a hypothesis regarding microbial contamination in cosmetics, learn techniques to culture and differentiate microorganisms from cosmetics, and propose best practices in cosmetics use based on their findings. Prior to the lab, students took a pretest to assess their knowledge of scientific hypotheses, microbiology, and cosmetic safety. In the first week, students were introduced to microbiological concepts and methodologies, and cosmetic terminology and safety. Students completed a hypothesis-writing exercise before formulating and testing their own hypotheses regarding cosmetic contamination. Students provided a cosmetic of their own and, in consultation with their lab group, chose one product for testing. Samples were serially diluted and plated on a variety of selective media. In the second week, students analyzed their plates to determine the presence and diversity of microbes and if their hypotheses were supported. Students completed a worksheet of their results and were given a posttest to assess their knowledge. Average test scores improved from 5.2 (pretest) to 7.8 (posttest), with p-values < 0.0001. Seventy-nine percent (79%) of students correctly identified hypotheses that were not falsifiable or lacked variables, and 89% of students improved their scores on questions concerning safe cosmetic use. Ninety-one percent (91%) of students demonstrated increased knowledge of microbial concepts and methods. Based on our results, this lab is an easy, yet effective, way to enhance knowledge of scientific concepts for nonmajors, while maintaining relevance to everyday life. PMID:23653761

  14. Testing the Granger noncausality hypothesis in stationary nonlinear models of unknown functional form

    DEFF Research Database (Denmark)

    Péguin-Feissolle, Anne; Strikholm, Birgit; Teräsvirta, Timo

    In this paper we propose a general method for testing the Granger noncausality hypothesis in stationary nonlinear models of unknown functional form. These tests are based on a Taylor expansion of the nonlinear model around a given point in the sample space. We study the performance of our tests...

  15. The Variability Hypothesis: The History of a Biological Model of Sex Differences in Intelligence.

    Science.gov (United States)

    Shields, Stephanie A.

    1982-01-01

    Describes the origin and development of the variability hypothesis as applied to the study of social and psychological sex differences. Explores changes in the hypothesis over time, social and scientific factors that fostered its acceptance, and possible parallels between the variability hypothesis and contemporary theories of sex differences.…

  16. Similar brain mechanism of hypothesis-testing between children and adults.

    Science.gov (United States)

    Li, Fuhong; Cao, Bihua; Cai, Xueli; Li, Hong

    2011-01-01

    Fourteen children and 15 adults were sequentially presented with triplets of cookies and were asked to learn what kinds of cookies were eatable while event-related potentials (ERPs) were recorded. The results locked to the third cookies that served to strengthen or reject a preliminary hypothesis showed that (1) the parietal P220 and frontal HRP (Hypothesis Reject Potential) was larger in reject condition than in strengthen condition for both age groups; (2) the intensive process of hypothesis testing activated most of the left brain. These results suggest that the logical function of the frontal lobe has been formed during the critical period of development of thinking.

  17. The limits to pride: A test of the pro-anorexia hypothesis.

    Science.gov (United States)

    Cornelius, Talea; Blanton, Hart

    2016-01-01

    Many social psychological models propose that positive self-conceptions promote self-esteem. An extreme version of this hypothesis is advanced in "pro-anorexia" communities: identifying with anorexia, in conjunction with disordered eating, can lead to higher self-esteem. The current study empirically tested this hypothesis. Results challenge the pro-anorexia hypothesis. Although those with higher levels of pro-anorexia identification trended towards higher self-esteem with increased disordered eating, this did not overcome the strong negative main effect of pro-anorexia identification. These data suggest a more effective strategy for promoting self-esteem is to encourage rejection of disordered eating and an anorexic identity.

  18. [Experimental testing of Pflüger's reflex hypothesis of menstruation in late 19th century].

    Science.gov (United States)

    Simmer, H H

    1980-07-01

    Pflüger's hypothesis of a nerve reflex as the cause of menstruation published in 1865 and accepted by many, nonetheless did not lead to experimental investigations for 25 years. According to this hypothesis the nerve reflex starts in the ovary by an increase of the intraovarian pressure by the growing follicles. In 1884 Adolph Kehrer proposed a program to test the nerve reflex, but only in 1890, Cohnstein artificially increased the intraovarian pressure in women by bimanual compression from the outside and the vagina. His results were not convincing. Six years later, Strassmann injected fluids into ovaries of animals and obtained changes in the uterus resembling those of oestrus. His results seemed to verify a prognosis derived from Pflüger's hypothesis. Thus, after a long interval, that hypothesis had become a paradigma. Though reasons can be given for the delay, it is little understood, why experimental testing started so late.

  19. Toward a new application of real-time electrophysiology: online optimization of cognitive neurosciences hypothesis testing.

    Science.gov (United States)

    Sanchez, Gaëtan; Daunizeau, Jean; Maby, Emmanuel; Bertrand, Olivier; Bompas, Aline; Mattout, Jérémie

    2014-01-23

    Brain-computer interfaces (BCIs) mostly rely on electrophysiological brain signals. Methodological and technical progress has largely solved the challenge of processing these signals online. The main issue that remains, however, is the identification of a reliable mapping between electrophysiological measures and relevant states of mind. This is why BCIs are highly dependent upon advances in cognitive neuroscience and neuroimaging research. Recently, psychological theories became more biologically plausible, leading to more realistic generative models of psychophysiological observations. Such complex interpretations of empirical data call for efficient and robust computational approaches that can deal with statistical model comparison, such as approximate Bayesian inference schemes. Importantly, the latter enable the optimization of a model selection error rate with respect to experimental control variables, yielding maximally powerful designs. In this paper, we use a Bayesian decision theoretic approach to cast model comparison in an online adaptive design optimization procedure. We show how to maximize design efficiency for individual healthy subjects or patients. Using simulated data, we demonstrate the face- and construct-validity of this approach and illustrate its extension to electrophysiology and multiple hypothesis testing based on recent psychophysiological models of perception. Finally, we discuss its implications for basic neuroscience and BCI itself.

  20. Toward a New Application of Real-Time Electrophysiology: Online Optimization of Cognitive Neurosciences Hypothesis Testing

    Directory of Open Access Journals (Sweden)

    Gaëtan Sanchez

    2014-01-01

    Full Text Available Brain-computer interfaces (BCIs mostly rely on electrophysiological brain signals. Methodological and technical progress has largely solved the challenge of processing these signals online. The main issue that remains, however, is the identification of a reliable mapping between electrophysiological measures and relevant states of mind. This is why BCIs are highly dependent upon advances in cognitive neuroscience and neuroimaging research. Recently, psychological theories became more biologically plausible, leading to more realistic generative models of psychophysiological observations. Such complex interpretations of empirical data call for efficient and robust computational approaches that can deal with statistical model comparison, such as approximate Bayesian inference schemes. Importantly, the latter enable the optimization of a model selection error rate with respect to experimental control variables, yielding maximally powerful designs. In this paper, we use a Bayesian decision theoretic approach to cast model comparison in an online adaptive design optimization procedure. We show how to maximize design efficiency for individual healthy subjects or patients. Using simulated data, we demonstrate the face- and construct-validity of this approach and illustrate its extension to electrophysiology and multiple hypothesis testing based on recent psychophysiological models of perception. Finally, we discuss its implications for basic neuroscience and BCI itself.

  1. Testing the phenotype-linked fertility hypothesis in the presence and absence of inbreeding

    Czech Academy of Sciences Publication Activity Database

    Forstmeier, W.; Ihle, M.; Opatová, Pavlína; Martin, K.; Knief, U.; Albrechtová, Jana; Albrecht, Tomáš; Kempenaers, B.

    2017-01-01

    Roč. 30, č. 5 (2017), s. 968-976 ISSN 1010-061X R&D Projects: GA ČR(CZ) GAP506/12/2472 Institutional support: RVO:68081766 Keywords : display behaviour * mate choice * phenotype-linked fertility hypothesis * precopulatory traits * sexual selection * sperm abnormalities * sperm quality * sperm velocity Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Genetics and heredity (medical genetics to be 3) Impact factor: 2.792, year: 2016

  2. When Null Hypothesis Significance Testing Is Unsuitable for Research: A Reassessment

    Science.gov (United States)

    Szucs, Denes; Ioannidis, John P. A.

    2017-01-01

    Null hypothesis significance testing (NHST) has several shortcomings that are likely contributing factors behind the widely debated replication crisis of (cognitive) neuroscience, psychology, and biomedical science in general. We review these shortcomings and suggest that, after sustained negative experience, NHST should no longer be the default, dominant statistical practice of all biomedical and psychological research. If theoretical predictions are weak we should not rely on all or nothing hypothesis tests. Different inferential methods may be most suitable for different types of research questions. Whenever researchers use NHST they should justify its use, and publish pre-study power calculations and effect sizes, including negative findings. Hypothesis-testing studies should be pre-registered and optimally raw data published. The current statistics lite educational approach for students that has sustained the widespread, spurious use of NHST should be phased out. PMID:28824397

  3. The Gumbel hypothesis test for left censored observations using regional earthquake records as an example

    Directory of Open Access Journals (Sweden)

    E. M. Thompson

    2011-01-01

    Full Text Available Annual maximum (AM time series are incomplete (i.e., censored when no events are included above the assumed censoring threshold (i.e., magnitude of completeness. We introduce a distrtibutional hypothesis test for left-censored Gumbel observations based on the probability plot correlation coefficient (PPCC. Critical values of the PPCC hypothesis test statistic are computed from Monte-Carlo simulations and are a function of sample size, censoring level, and significance level. When applied to a global catalog of earthquake observations, the left-censored Gumbel PPCC tests are unable to reject the Gumbel hypothesis for 45 of 46 seismic regions. We apply four different field significance tests for combining individual tests into a collective hypothesis test. None of the field significance tests are able to reject the global hypothesis that AM earthquake magnitudes arise from a Gumbel distribution. Because the field significance levels are not conclusive, we also compute the likelihood that these field significance tests are unable to reject the Gumbel model when the samples arise from a more complex distributional alternative. A power study documents that the censored Gumbel PPCC test is unable to reject some important and viable Generalized Extreme Value (GEV alternatives. Thus, we cannot rule out the possibility that the global AM earthquake time series could arise from a GEV distribution with a finite upper bound, also known as a reverse Weibull distribution. Our power study also indicates that the binomial and uniform field significance tests are substantially more powerful than the more commonly used Bonferonni and false discovery rate multiple comparison procedures.

  4. Testing of Biologically Inhibiting Surface

    DEFF Research Database (Denmark)

    Bill Madsen, Thomas; Larsen, Erup

    2003-01-01

    The main purpose of this course is to examine a newly developed biologically inhibiting material with regards to galvanic corrosion and electrochemical properties. More in detail, the concern was how the material would react when exposed to cleaning agents, here under CIP cleaning (Cleaning...

  5. Why do mothers favor girls and fathers, boys? : A hypothesis and a test of investment disparity.

    Science.gov (United States)

    Godoy, Ricardo; Reyes-García, Victoria; McDade, Thomas; Tanner, Susan; Leonard, William R; Huanca, Tomás; Vadez, Vincent; Patel, Karishma

    2006-06-01

    Growing evidence suggests mothers invest more in girls than boys and fathers more in boys than girls. We develop a hypothesis that predicts preference for girls by the parent facing more resource constraints and preference for boys by the parent facing less constraint. We test the hypothesis with panel data from the Tsimane', a foraging-farming society in the Bolivian Amazon. Tsimane' mothers face more resource constraints than fathers. As predicted, mother's wealth protected girl's BMI, but father's wealth had weak effects on boy's BMI. Numerous tests yielded robust results, including those that controlled for fixed effects of child and household.

  6. Is it better to select or to receive? Learning via active and passive hypothesis testing.

    Science.gov (United States)

    Markant, Douglas B; Gureckis, Todd M

    2014-02-01

    People can test hypotheses through either selection or reception. In a selection task, the learner actively chooses observations to test his or her beliefs, whereas in reception tasks data are passively encountered. People routinely use both forms of testing in everyday life, but the critical psychological differences between selection and reception learning remain poorly understood. One hypothesis is that selection learning improves learning performance by enhancing generic cognitive processes related to motivation, attention, and engagement. Alternatively, we suggest that differences between these 2 learning modes derives from a hypothesis-dependent sampling bias that is introduced when a person collects data to test his or her own individual hypothesis. Drawing on influential models of sequential hypothesis-testing behavior, we show that such a bias (a) can lead to the collection of data that facilitates learning compared with reception learning and (b) can be more effective than observing the selections of another person. We then report a novel experiment based on a popular category learning paradigm that compares reception and selection learning. We additionally compare selection learners to a set of "yoked" participants who viewed the exact same sequence of observations under reception conditions. The results revealed systematic differences in performance that depended on the learner's role in collecting information and the abstract structure of the problem.

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

    Science.gov (United States)

    Vock, Miriam; Preckel, Franzis; Holling, Heinz

    2011-01-01

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

  8. A critical discussion of null hypothesis significance testing and statistical power analysis within psychological research

    DEFF Research Database (Denmark)

    Jones, Allan; Sommerlund, Bo

    2007-01-01

    The uses of null hypothesis significance testing (NHST) and statistical power analysis within psychological research are critically discussed. The article looks at the problems of relying solely on NHST when dealing with small and large sample sizes. The use of power-analysis in estimating...

  9. The Harm Done to Reproducibility by the Culture of Null Hypothesis Significance Testing.

    Science.gov (United States)

    Lash, Timothy L

    2017-09-15

    In the last few years, stakeholders in the scientific community have raised alarms about a perceived lack of reproducibility of scientific results. In reaction, guidelines for journals have been promulgated and grant applicants have been asked to address the rigor and reproducibility of their proposed projects. Neither solution addresses a primary culprit, which is the culture of null hypothesis significance testing that dominates statistical analysis and inference. In an innovative research enterprise, selection of results for further evaluation based on null hypothesis significance testing is doomed to yield a low proportion of reproducible results and a high proportion of effects that are initially overestimated. In addition, the culture of null hypothesis significance testing discourages quantitative adjustments to account for systematic errors and quantitative incorporation of prior information. These strategies would otherwise improve reproducibility and have not been previously proposed in the widely cited literature on this topic. Without discarding the culture of null hypothesis significance testing and implementing these alternative methods for statistical analysis and inference, all other strategies for improving reproducibility will yield marginal gains at best. © The Author(s) 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. Speech production in people who stutter: Testing the motor plan assembly hypothesis

    NARCIS (Netherlands)

    Lieshout, P.H.H.M. van; Hulstijn, W.; Peters, H.F.M.

    1996-01-01

    The main purpose of the present study was to test the hypothesis that persons who stutter, when compared to persons who do not stutter, are less able to assemble abstract motor plans for short verbal responses. Subjects were adult males who stutter and age- and sex-matched control speakers, who were

  11. A Multivariate Test of the Bott Hypothesis in an Urban Irish Setting

    Science.gov (United States)

    Gordon, Michael; Downing, Helen

    1978-01-01

    Using a sample of 686 married Irish women in Cork City the Bott hypothesis was tested, and the results of a multivariate regression analysis revealed that neither network connectedness nor the strength of the respondent's emotional ties to the network had any explanatory power. (Author)

  12. Different meaning of the p-value in exploratory and confirmatory hypothesis testing

    DEFF Research Database (Denmark)

    Gerke, Oke; Høilund-Carlsen, Poul Flemming; Vach, Werner

    2011-01-01

    The outcome of clinical studies is often reduced to the statistical significance of results by indicating a p-value below the 5% significance level. Hypothesis testing and, through that, the p-value is commonly used, but their meaning is frequently misinterpreted in clinical research. The concept...

  13. Bayesian Hypothesis Testing for Psychologists: A Tutorial on the Savage-Dickey Method

    Science.gov (United States)

    Wagenmakers, Eric-Jan; Lodewyckx, Tom; Kuriyal, Himanshu; Grasman, Raoul

    2010-01-01

    In the field of cognitive psychology, the "p"-value hypothesis test has established a stranglehold on statistical reporting. This is unfortunate, as the "p"-value provides at best a rough estimate of the evidence that the data provide for the presence of an experimental effect. An alternative and arguably more appropriate measure of evidence is…

  14. Robust Means Modeling: An Alternative for Hypothesis Testing of Independent Means under Variance Heterogeneity and Nonnormality

    Science.gov (United States)

    Fan, Weihua; Hancock, Gregory R.

    2012-01-01

    This study proposes robust means modeling (RMM) approaches for hypothesis testing of mean differences for between-subjects designs in order to control the biasing effects of nonnormality and variance inequality. Drawing from structural equation modeling (SEM), the RMM approaches make no assumption of variance homogeneity and employ robust…

  15. Visual Working Memory and Number Sense: Testing the Double Deficit Hypothesis in Mathematics

    Science.gov (United States)

    Toll, Sylke W. M.; Kroesbergen, Evelyn H.; Van Luit, Johannes E. H.

    2016-01-01

    Background: Evidence exists that there are two main underlying cognitive factors in mathematical difficulties: working memory and number sense. It is suggested that real math difficulties appear when both working memory and number sense are weak, here referred to as the double deficit (DD) hypothesis. Aims: The aim of this study was to test the DD…

  16. Testing the fire-sale FDI hypothesis for the European financial crisis

    NARCIS (Netherlands)

    Weitzel, G.U.; Kling, G.; Gerritsen, D.

    2014-01-01

    Using a panel of corporate transactions in 27 EU countries from 1999 to 2012, we investigate the impact of the financial crisis on the market for corporate assets. In particular, we test the ‘fire-sale FDI’ hypothesis by analyzing the number of cross-border transactions, the price of corporate

  17. Testing the Fire-Sale FDI Hypothesis for the European Financial Crisis

    NARCIS (Netherlands)

    Kling, G.; Gerritsen, Dirk; Weitzel, Gustav Utz

    2014-01-01

    Using a panel of corporate transactions in 27 EU countries from 1999 to 2012, we investigate the impact of the financial crisis on the market for corporate assets. In particular, we test the ‘fire-sale FDI’ hypothesis by analyzing the number of cross-border transactions, the price of corporate

  18. Is conscious stimulus identification dependent on knowledge of the perceptual modality? Testing the "source misidentification hypothesis"

    DEFF Research Database (Denmark)

    Overgaard, Morten; Lindeløv, Jonas Kristoffer; Svejstrup, Stinna

    2013-01-01

    to this knowledge (whether the stimulus was visual, auditory, or something else). We test this hypothesis in healthy subjects, asking them to report whether a masked stimulus was presented auditorily or visually, what the stimulus was, and how clearly they experienced the stimulus using the Perceptual Awareness...

  19. The Genesis of Pedophilia: Testing the "Abuse-to-Abuser" Hypothesis.

    Science.gov (United States)

    Fedoroff, J. Paul; Pinkus, Shari

    1996-01-01

    This study tested three versions of the "abuse-to-abuser" hypothesis by comparing men with personal histories of sexual abuse and men without sexual abuse histories. There was a statistically non-significant trend for assaulted offenders to be more likely as adults to commit genital assaults on children. Implications for the abuse-to-abuser…

  20. Concerns regarding a call for pluralism of information theory and hypothesis testing

    Science.gov (United States)

    Lukacs, P.M.; Thompson, W.L.; Kendall, W.L.; Gould, W.R.; Doherty, P.F.; Burnham, K.P.; Anderson, D.R.

    2007-01-01

    1. Stephens et al . (2005) argue for `pluralism? in statistical analysis, combining null hypothesis testing and information-theoretic (I-T) methods. We show that I-T methods are more informative even in single variable problems and we provide an ecological example. 2. I-T methods allow inferences to be made from multiple models simultaneously. We believe multimodel inference is the future of data analysis, which cannot be achieved with null hypothesis-testing approaches. 3. We argue for a stronger emphasis on critical thinking in science in general and less reliance on exploratory data analysis and data dredging. Deriving alternative hypotheses is central to science; deriving a single interesting science hypothesis and then comparing it to a default null hypothesis (e.g. `no difference?) is not an efficient strategy for gaining knowledge. We think this single-hypothesis strategy has been relied upon too often in the past. 4. We clarify misconceptions presented by Stephens et al . (2005). 5. We think inference should be made about models, directly linked to scientific hypotheses, and their parameters conditioned on data, Prob(Hj| data). I-T methods provide a basis for this inference. Null hypothesis testing merely provides a probability statement about the data conditioned on a null model, Prob(data |H0). 6. Synthesis and applications. I-T methods provide a more informative approach to inference. I-T methods provide a direct measure of evidence for or against hypotheses and a means to consider simultaneously multiple hypotheses as a basis for rigorous inference. Progress in our science can be accelerated if modern methods can be used intelligently; this includes various I-T and Bayesian methods.

  1. Effects of native biodiversity on grape loss of four castes: testing the biotic resistance hypothesis

    Directory of Open Access Journals (Sweden)

    M. Nereu

    2018-02-01

    Full Text Available Management of agricultural landscapes can influence the biodiversity and the ecological services provided by these ecosystems, such as natural biological pest control. Viticulture is a very important economic activity in most countries with Mediterranean climate, often shaping their landscapes and culture. Grape production is affected by a number of pests and diseases, and farmers use prophylactic and response-driven pesticides to control these pests. Here we quantified the main biotic causes of crop losses in four grape castes, two red (Touriga Nacional and Baga and two white (Arinto and Chardonnay, and evaluated the potential effect of native biodiversity to provide biotic resistance to pest outbreaks and grape losses. Specifically, the diversity and abundance of bird and insect communities in these vineyards were quantified and divided into functional guilds (pest, neutral or auxiliary, to test whether these natural communities hold the potential to naturally control grape pests (biotic resistance hypothesis under normal vineyard management (including pesticide application regimes. A potential association between distance to the vineyard edge and grape losses was also evaluated. We recorded a very small proportion of grape losses (mean  =  0.6 %; max  =  7.5 %, with insect pests showing a preference for the castes Baga (red and Chardonnay (white, while bird pests avoided the caste Arinto (white. Grape color did not influence losses caused by insect pests, but birds showed a preference for red castes. The caste Baga was also more vulnerable to losses caused by fungi. Despite their low impact on grape production, most insects and birds detected in the six vineyards were pests, which entails a potentially low level of biotic resistance in this highly managed agricultural ecosystem. Further research is necessary to fully evaluate the role of functional biodiversity in vineyards, particularly if alternative production processes

  2. Tests of the planetary hypothesis for PTFO 8-8695b

    DEFF Research Database (Denmark)

    Yu, Liang; Winn, Joshua N.; Gillon, Michaël

    2015-01-01

    planetary orbit. Our spectroscopy also revealed strong, time-variable, high-velocity H{\\alpha} and Ca H & K emission features. All these observations cast doubt on the planetary hypothesis, and suggest instead that the fading events represent starspots, eclipses by circumstellar dust, or occultations......The T Tauri star PTFO 8-8695 exhibits periodic fading events that have been interpreted as the transits of a giant planet on a precessing orbit. Here we present three tests of the planet hypothesis. First, we sought evidence for the secular changes in light-curve morphology that are predicted...

  3. Testing Informative Hypotheses in SEM Increases Power: An Illustration Contrasting Classical Hypothesis Testing with a Parametric Bootstrap Approach

    Science.gov (United States)

    van de Schoot, Rens; Strohmeier, Dagmar

    2011-01-01

    In the present paper, the application of a parametric bootstrap procedure, as described by van de Schoot, Hoijtink, and Dekovic (2010), will be applied to demonstrate that a direct test of an informative hypothesis offers more informative results compared to testing traditional null hypotheses against catch-all rivals. Also, more power can be…

  4. General Multidecision Theory: Hypothesis Testing and Changepoint Detection with Applications to Homeland Security

    Science.gov (United States)

    2014-10-06

    Manuscript, 1977. [4] I. V. Pavlov . Sequential procedure of testing composite hypotheses with applications to the Kiefer-Weiss problem. Theory of...SECURITY CLASSIFICATION OF: The objective was to develop general theories of sequential hypothesis testing and quickest change detection for complex...multi-population stochastic models, as well as to apply these theories to automatic threat detection and classification with low false alarm and miss

  5. Critical evidence: a test of the critical-period hypothesis for second-language acquisition.

    Science.gov (United States)

    Hakuta, Kenji; Bialystok, Ellen; Wiley, Edward

    2003-01-01

    The critical-period hypothesis for second-language acquisition was tested on data from the 1990 U.S. Census using responses from 2.3 million immigrants with Spanish or Chinese language backgrounds. The analyses tested a key prediction of the hypothesis, namely, that the line regressing second-language attainment on age of immigration would be markedly different on either side of the critical-age point. Predictions tested were that there would be a difference in slope, a difference in the mean while controlling for slope, or both. The results showed large linear effects for level of education and for age of immigration, but a negligible amount of additional variance was accounted for when the parameters for difference in slope and difference in means were estimated. Thus, the pattern of decline in second-language acquisition failed to produce the discontinuity that is an essential hallmark of a critical period.

  6. A robust hypothesis test for the sensitive detection of constant speed radiation moving sources

    Energy Technology Data Exchange (ETDEWEB)

    Dumazert, Jonathan, E-mail: jonathan.dumazert@cea.fr [CEA, LIST, Laboratoire Capteurs Architectures Electroniques, 91191 Gif-sur-Yvette (France); Coulon, Romain; Kondrasovs, Vladimir; Boudergui, Karim; Moline, Yoann; Sannié, Guillaume; Gameiro, Jordan; Normand, Stéphane [CEA, LIST, Laboratoire Capteurs Architectures Electroniques, 91191 Gif-sur-Yvette (France); Méchin, Laurence [CNRS, UCBN, Groupe de Recherche en Informatique, Image, Automatique et Instrumentation de Caen, 14050 Caen (France)

    2015-09-21

    Radiation Portal Monitors are deployed in linear networks to detect radiological material in motion. As a complement to single and multichannel detection algorithms, inefficient under too low signal-to-noise ratios, temporal correlation algorithms have been introduced. Test hypothesis methods based on empirically estimated mean and variance of the signals delivered by the different channels have shown significant gain in terms of a tradeoff between detection sensitivity and false alarm probability. This paper discloses the concept of a new hypothesis test for temporal correlation detection methods, taking advantage of the Poisson nature of the registered counting signals, and establishes a benchmark between this test and its empirical counterpart. The simulation study validates that in the four relevant configurations of a pedestrian source carrier under respectively high and low count rate radioactive backgrounds, and a vehicle source carrier under the same respectively high and low count rate radioactive backgrounds, the newly introduced hypothesis test ensures a significantly improved compromise between sensitivity and false alarm. It also guarantees that the optimal coverage factor for this compromise remains stable regardless of signal-to-noise ratio variations between 2 and 0.8, therefore allowing the final user to parametrize the test with the sole prior knowledge of background amplitude.

  7. A robust hypothesis test for the sensitive detection of constant speed radiation moving sources

    International Nuclear Information System (INIS)

    Dumazert, Jonathan; Coulon, Romain; Kondrasovs, Vladimir; Boudergui, Karim; Moline, Yoann; Sannié, Guillaume; Gameiro, Jordan; Normand, Stéphane; Méchin, Laurence

    2015-01-01

    Radiation Portal Monitors are deployed in linear networks to detect radiological material in motion. As a complement to single and multichannel detection algorithms, inefficient under too low signal-to-noise ratios, temporal correlation algorithms have been introduced. Test hypothesis methods based on empirically estimated mean and variance of the signals delivered by the different channels have shown significant gain in terms of a tradeoff between detection sensitivity and false alarm probability. This paper discloses the concept of a new hypothesis test for temporal correlation detection methods, taking advantage of the Poisson nature of the registered counting signals, and establishes a benchmark between this test and its empirical counterpart. The simulation study validates that in the four relevant configurations of a pedestrian source carrier under respectively high and low count rate radioactive backgrounds, and a vehicle source carrier under the same respectively high and low count rate radioactive backgrounds, the newly introduced hypothesis test ensures a significantly improved compromise between sensitivity and false alarm. It also guarantees that the optimal coverage factor for this compromise remains stable regardless of signal-to-noise ratio variations between 2 and 0.8, therefore allowing the final user to parametrize the test with the sole prior knowledge of background amplitude

  8. Phi index: a new metric to test the flush early and avoid the rush hypothesis.

    Science.gov (United States)

    Samia, Diogo S M; Blumstein, Daniel T

    2014-01-01

    Optimal escape theory states that animals should counterbalance the costs and benefits of flight when escaping from a potential predator. However, in apparent contradiction with this well-established optimality model, birds and mammals generally initiate escape soon after beginning to monitor an approaching threat, a phenomena codified as the "Flush Early and Avoid the Rush" (FEAR) hypothesis. Typically, the FEAR hypothesis is tested using correlational statistics and is supported when there is a strong relationship between the distance at which an individual first responds behaviorally to an approaching predator (alert distance, AD), and its flight initiation distance (the distance at which it flees the approaching predator, FID). However, such correlational statistics are both inadequate to analyze relationships constrained by an envelope (such as that in the AD-FID relationship) and are sensitive to outliers with high leverage, which can lead one to erroneous conclusions. To overcome these statistical concerns we develop the phi index (Φ), a distribution-free metric to evaluate the goodness of fit of a 1:1 relationship in a constraint envelope (the prediction of the FEAR hypothesis). Using both simulation and empirical data, we conclude that Φ is superior to traditional correlational analyses because it explicitly tests the FEAR prediction, is robust to outliers, and it controls for the disproportionate influence of observations from large predictor values (caused by the constrained envelope in AD-FID relationship). Importantly, by analyzing the empirical data we corroborate the strong effect that alertness has on flight as stated by the FEAR hypothesis.

  9. Congruence analysis of geodetic networks - hypothesis tests versus model selection by information criteria

    Science.gov (United States)

    Lehmann, Rüdiger; Lösler, Michael

    2017-12-01

    Geodetic deformation analysis can be interpreted as a model selection problem. The null model indicates that no deformation has occurred. It is opposed to a number of alternative models, which stipulate different deformation patterns. A common way to select the right model is the usage of a statistical hypothesis test. However, since we have to test a series of deformation patterns, this must be a multiple test. As an alternative solution for the test problem, we propose the p-value approach. Another approach arises from information theory. Here, the Akaike information criterion (AIC) or some alternative is used to select an appropriate model for a given set of observations. Both approaches are discussed and applied to two test scenarios: A synthetic levelling network and the Delft test data set. It is demonstrated that they work but behave differently, sometimes even producing different results. Hypothesis tests are well-established in geodesy, but may suffer from an unfavourable choice of the decision error rates. The multiple test also suffers from statistical dependencies between the test statistics, which are neglected. Both problems are overcome by applying information criterions like AIC.

  10. A test of the herbivore optimization hypothesis using muskoxen and a graminoid meadow plant community

    Directory of Open Access Journals (Sweden)

    David L. Smith

    1996-01-01

    Full Text Available A prediction from the herbivore optimization hypothesis is that grazing by herbivores at moderate intensities will increase net above-ground primary productivity more than at lower or higher intensities. I tested this hypothesis in an area of high muskox {Ovibos moschatus density on north-central Banks Island, Northwest Territories, Canada (73°50'N, 119°53'W. Plots (1 m2 in graminoid meadows dominated by cottongrass (Eriophorum triste were either clipped, exposed to muskoxen, protected for part of one growing season, or permanently protected. This resulted in the removal of 22-44%, 10-39%, 0-39% or 0%, respectively, of shoot tissue during each growing season. Contrary to the predictions of the herbivore optimization hypothesis, productivity did not increase across this range of tissue removal. Productivity of plants clipped at 1.5 cm above ground once or twice per growing season, declined by 60+/-5% in 64% of the tests. The productivity of plants grazed by muskoxen declined by 56+/-7% in 25% of the tests. No significant change in productivity was observed in 36% and 75% of the tests in clipped and grazed treatments, respecrively. Clipping and grazing reduced below-ground standing crop except where removals were small. Grazing and clipping did not stimulate productivity of north-central Banks Island graminoid meadows.

  11. Hypothesis tests for the detection of constant speed radiation moving sources

    Energy Technology Data Exchange (ETDEWEB)

    Dumazert, Jonathan; Coulon, Romain; Kondrasovs, Vladimir; Boudergui, Karim; Sannie, Guillaume; Gameiro, Jordan; Normand, Stephane [CEA, LIST, Laboratoire Capteurs Architectures Electroniques, 99 Gif-sur-Yvette, (France); Mechin, Laurence [CNRS, UCBN, Groupe de Recherche en Informatique, Image, Automatique et Instrumentation de Caen, 4050 Caen, (France)

    2015-07-01

    Radiation Portal Monitors are deployed in linear network to detect radiological material in motion. As a complement to single and multichannel detection algorithms, inefficient under too low signal to noise ratios, temporal correlation algorithms have been introduced. Test hypothesis methods based on empirically estimated mean and variance of the signals delivered by the different channels have shown significant gain in terms of a tradeoff between detection sensitivity and false alarm probability. This paper discloses the concept of a new hypothesis test for temporal correlation detection methods, taking advantage of the Poisson nature of the registered counting signals, and establishes a benchmark between this test and its empirical counterpart. The simulation study validates that in the four relevant configurations of a pedestrian source carrier under respectively high and low count rate radioactive background, and a vehicle source carrier under the same respectively high and low count rate radioactive background, the newly introduced hypothesis test ensures a significantly improved compromise between sensitivity and false alarm, while guaranteeing the stability of its optimization parameter regardless of signal to noise ratio variations between 2 to 0.8. (authors)

  12. Null hypothesis significance tests. A mix-up of two different theories

    DEFF Research Database (Denmark)

    Schneider, Jesper Wiborg

    2015-01-01

    Null hypothesis statistical significance tests (NHST) are widely used in quantitative research in the empirical sciences including scientometrics. Nevertheless, since their introduction nearly a century ago significance tests have been controversial. Many researchers are not aware of the numerous......-Bayesian interpretations. This is undoubtedly a major reason why NHST is very often misunderstood. But NHST also has intrinsic logical problems and the epistemic range of the information provided by such tests is much more limited than most researchers recognize. In this article we introduce to the scientometric community...... of the misunderstandings with examples from the scientometric literature and bring forward some modest recommendations for a more sound practice in quantitative data analysis....

  13. Habitat fragmentation, vole population fluctuations, and the ROMPA hypothesis: An experimental test using model landscapes.

    Science.gov (United States)

    Batzli, George O

    2016-11-01

    Increased habitat fragmentation leads to smaller size of habitat patches and to greater distance between patches. The ROMPA hypothesis (ratio of optimal to marginal patch area) uniquely links vole population fluctuations to the composition of the landscape. It states that as ROMPA decreases (fragmentation increases), vole population fluctuations will increase (including the tendency to display multi-annual cycles in abundance) because decreased proportions of optimal habitat result in greater population declines and longer recovery time after a harsh season. To date, only comparative observations in the field have supported the hypothesis. This paper reports the results of the first experimental test. I used prairie voles, Microtus ochrogaster, and mowed grassland to create model landscapes with 3 levels of ROMPA (high with 25% mowed, medium with 50% mowed and low with 75% mowed). As ROMPA decreased, distances between patches of favorable habitat (high cover) increased owing to a greater proportion of unfavorable (mowed) habitat. Results from the first year with intensive live trapping indicated that the preconditions for operation of the hypothesis existed (inversely density dependent emigration and, as ROMPA decreased, increased per capita mortality and decreased per capita movement between optimal patches). Nevertheless, contrary to the prediction of the hypothesis that populations in landscapes with high ROMPA should have the lowest variability, 5 years of trapping indicated that variability was lowest with medium ROMPA. The design of field experiments may never be perfect, but these results indicate that the ROMPA hypothesis needs further rigorous testing. © 2016 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

  14. Causal connections in the acquisition of an orthographic rule: a test of Uta Frith's developmental hypothesis.

    Science.gov (United States)

    Davis, Claire; Bryant, Peter

    2006-08-01

    In a longitudinal study we tested Frith's causal hypothesis that children first gain orthographic knowledge through reading and then later, as a consequence, through spelling. Children from Years 2 and 3 were tested three times over two years on their reading and spelling of pseudo-words which conformed to the conditional orthographic rule, the 'final -e' or 'split-digraph' rule. Cross-lagged panel correlation analyses suggested that the children's success in reading split-digraph words was a causal determinant of their learning to use split-digraphs in spelling, in the 7- to 8-year period and, with one year-group but not with the other, in the 8- to 9-year period. In the 9- to 10-year period children's success in reading no longer seemed to affect their spelling. These results strongly support Frith's causal hypothesis about the development of orthographic knowledge.

  15. Statistical hypothesis testing and common misinterpretations: Should we abandon p-value in forensic science applications?

    Science.gov (United States)

    Taroni, F; Biedermann, A; Bozza, S

    2016-02-01

    Many people regard the concept of hypothesis testing as fundamental to inferential statistics. Various schools of thought, in particular frequentist and Bayesian, have promoted radically different solutions for taking a decision about the plausibility of competing hypotheses. Comprehensive philosophical comparisons about their advantages and drawbacks are widely available and continue to span over large debates in the literature. More recently, controversial discussion was initiated by an editorial decision of a scientific journal [1] to refuse any paper submitted for publication containing null hypothesis testing procedures. Since the large majority of papers published in forensic journals propose the evaluation of statistical evidence based on the so called p-values, it is of interest to expose the discussion of this journal's decision within the forensic science community. This paper aims to provide forensic science researchers with a primer on the main concepts and their implications for making informed methodological choices. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  16. Determinants of Electoral Outcomes: A simple Test of Meltzer and Richard's Hypothesis

    OpenAIRE

    Benoît Le Maux; Federica Minardy; Charlotte Magalhaes

    2011-01-01

    The present study aims to test Meltzer and Richard’s (1981) hypothesis that lower-income individuals vote for candidates who favor higher taxes and more redistribution. Assuming that left-wing parties advocate a general increase in taxation, we estimate a vote function for the French Cantonal elections. We show clear-cut evidence that an increasing proportion of voters receiving social assistance raises the number of votes in favor of left-wing parties. This result highlights the importance o...

  17. Testing the sexual imagination hypothesis for gender differences in response to infidelity.

    Science.gov (United States)

    Kato, Tsukasa

    2014-11-29

    Evolutionary psychologists hypothesized that men are more upset by sexual infidelity than women are, whereas women are more upset by emotional infidelity than men are. On the other hand, the sexual imagination hypothesis states that gender differences in infidelity responses are derived from explicit men's sexual imagery. Based on the latter hypothesis, we hypothesized that although men would report being more distressed by sexual infidelity than women who were not in a committed relationship (NCR), no gender difference would be reported in a committed relationship (CR). These two hypotheses were tested with 598 participants in a CR and 1,643 participants in a NCR. No significant gender difference was found sexual infidelity response in the CR group (d=0.008, a power of .956), whereas men were more upset than women about sexual infidelity in the NCR group. Moreover, a significant interaction between gender and infidelity type was found in the NCR, whereas no significant interaction between gender and infidelity type was observed in the CR group (partial η2=0.005, a power of .943). Our findings supported the sexual imagination hypothesis but were inconsistent with the EJM hypothesis.

  18. Social competition and plasma testosterone profile in domesticated canaries: an experimental test of the challenge hypothesis.

    Science.gov (United States)

    Parisot, Maëlle; Tanvez, Aurélie; Lacroix, André; Vallet, Eric; Béguin, Nathalie; Leboucher, Gérard

    2005-08-01

    The challenge hypothesis predicts that plasma testosterone (T) concentration is high when male-male competitions are high and decreases when males are engaged in paternal care. In monogamous species, T concentration increases at the beginning of the breeding period and decreases after egg laying. According to the challenge hypothesis, increasing competition should also lead to T increase. The aim of our study was to test this hypothesis. In a first experiment, we measured the T profile of domesticated canaries housed with their mate in separated cages without competition. In a second one, we created a competition by housing male and female domestic canaries together (in an aviary) and emphasized this competition by limiting food access. We also studied social status effect. Our results showed no effect of social status in both sexes and no differences in female's T concentration. Concerning males, we obtained a clear monogamous T profile from the ones housed in a low competition situation and a polygamous profile from the others housed in high competition situation. Thus, our results support the hypothesis of the plasticity of the mechanisms controlling T concentration according to environmental conditions.

  19. The comprehension of sentences with unaccusative verbs in aphasia: a test of the intervener hypothesis.

    Science.gov (United States)

    Sullivan, Natalie; Walenski, Matthew; Love, Tracy; Shapiro, Lewis P

    2017-01-01

    It is well accepted that individuals with agrammatic Broca's aphasia have difficulty comprehending some sentences with filler-gap dependencies. While investigations of these difficulties have been conducted with several different sentence types (e.g., object relatives, Wh -questions), we explore sentences containing unaccusative verbs, which arguably have a single noun phrase (NP) that is base-generated in object position but then is displaced to surface subject position. Unaccusative verbs provide an ideal test case for a particular hypothesis about the comprehension disorder-the Intervener Hypothesis-that posits that the difficulty individuals with agrammatic Broca's aphasia have comprehending sentences containing filler-gap dependencies results from similarity-based interference caused by the presence of an intervening NP between the two elements of a syntactic chain. To assess a particular account of the comprehension deficit in agrammatic Broca's aphasia-the Intervener Hypothesis. We used a sentence-picture matching task to determine if listeners with agrammatic Broca's aphasia (LWBA) and age-matched neurologically unimpaired controls (AMC) have difficulty comprehending unaccusative verbs when placed in subject relative and complement phrase (CP) constructions. We found above-chance comprehension of both sentence constructions with the AMC participants. In contrast, we found above-chance comprehension of CP sentences containing unaccusative verbs but poor comprehension of subject relative sentences containing unaccusative verbs for the LWBA. These results provide support for the Intervener Hypothesis, wherein the presence of an intervening NP between two elements of a filler-gap dependency adversely affects sentence comprehension.

  20. Hierarchical models in ecology: confidence intervals, hypothesis testing, and model selection using data cloning.

    Science.gov (United States)

    Ponciano, José Miguel; Taper, Mark L; Dennis, Brian; Lele, Subhash R

    2009-02-01

    Hierarchical statistical models are increasingly being used to describe complex ecological processes. The data cloning (DC) method is a new general technique that uses Markov chain Monte Carlo (MCMC) algorithms to compute maximum likelihood (ML) estimates along with their asymptotic variance estimates for hierarchical models. Despite its generality, the method has two inferential limitations. First, it only provides Wald-type confidence intervals, known to be inaccurate in small samples. Second, it only yields ML parameter estimates, but not the maximized likelihood values used for profile likelihood intervals, likelihood ratio hypothesis tests, and information-theoretic model selection. Here we describe how to overcome these inferential limitations with a computationally efficient method for calculating likelihood ratios via data cloning. The ability to calculate likelihood ratios allows one to do hypothesis tests, construct accurate confidence intervals and undertake information-based model selection with hierarchical models in a frequentist context. To demonstrate the use of these tools with complex ecological models, we reanalyze part of Gause's classic Paramecium data with state-space population models containing both environmental noise and sampling error. The analysis results include improved confidence intervals for parameters, a hypothesis test of laboratory replication, and a comparison of the Beverton-Holt and the Ricker growth forms based on a model selection index.

  1. A phylogenetic test of the Red Queen Hypothesis: outcrossing and parasitism in the Nematode phylum.

    Science.gov (United States)

    Gibson, Amanda Kyle; Fuentes, Jesualdo Arturo

    2015-02-01

    Sexual outcrossing is costly relative to selfing and asexuality, yet it is ubiquitous in nature, a paradox that has long puzzled evolutionary biologists. The Red Queen Hypothesis argues that outcrossing is maintained by antagonistic interactions between host and parasites. Most tests of this hypothesis focus on the maintenance of outcrossing in hosts. The Red Queen makes an additional prediction that parasitic taxa are more likely to be outcrossing than their free-living relatives. We test this prediction in the diverse Nematode phylum using phylogenetic comparative methods to evaluate trait correlations. In support of the Red Queen, we demonstrate a significant correlation between parasitism and outcrossing in this clade. We find that this correlation is driven by animal parasites, for which outcrossing is significantly enriched relative to both free-living and plant parasitic taxa. Finally, we test hypotheses for the evolutionary history underlying the correlation of outcrossing and animal parasitism. Our results demonstrate that selfing and asexuality are significantly less likely to arise on parasitic lineages than on free-living ones. The findings of this study are consistent with the Red Queen Hypothesis. Moreover, they suggest that the maintenance of genetic variation is an important factor in the persistence of parasitic lineages. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  2. Advertising investment as a tool for boosting consumption: testing Galbraith's hypothesis for Spain

    Directory of Open Access Journals (Sweden)

    Valentín-Alejandro Martínez-Fernández

    2014-12-01

    Full Text Available The recession that most of the world economies have been facing in the last years has caused a great interest in the study of its macroeconomic effects. In this context, a debate has resurged regarding the advertising investment, as for its potential capacity to impel the consumer spending and to impact positively on the economic recovery. This idea, sustained in the so-called Galbraith's hypothesis, constitutes the core of this paper, where the main objective is to test that hypothesis by means of an empirical analysis. In this study, we focus on the Spanish case and the data correspond to the period 1976 -2010. A cointegration analysis is carried out, using two different approaches (Engle-Granger test and Gregory-Hansen test, respectively, to determine if there is any relationship between the advertising investment and six macromagnitudes (GDP, National Income, Consumption, Savings and Fixed Capital Formation, as well as the registered unemployment rate. Based on the results obtained, we conclude that Galbraith's hypothesis is not fulfilled for the Spanish case.

  3. Neuroticism, intelligence, and intra-individual variability in elementary cognitive tasks: testing the mental noise hypothesis.

    Science.gov (United States)

    Colom, Roberto; Quiroga, Ma Angeles

    2009-08-01

    Some studies show positive correlations between intraindividual variability in elementary speed measures (reflecting processing efficiency) and individual differences in neuroticism (reflecting instability in behaviour). The so-called neural noise hypothesis assumes that higher levels of noise are related both to smaller indices of processing efficiency and greater levels of neuroticism. Here, we test this hypothesis measuring mental speed by means of three elementary cognitive tasks tapping similar basic processes but varying systematically their content (verbal, numerical, and spatial). Neuroticism and intelligence are also measured. The sample comprised 196 undergraduate psychology students. The results show that (1) processing efficiency is generally unrelated to individual differences in neuroticism, (2) processing speed and efficiency correlate with intelligence, and (3) only the efficiency index is genuinely related to intelligence when the colinearity between speed and efficiency is controlled.

  4. Aging and motor variability: a test of the neural noise hypothesis.

    Science.gov (United States)

    Sosnoff, Jacob J; Newell, Karl M

    2011-07-01

    Experimental tests of the neural noise hypothesis of aging, which holds that aging-related increments in motor variability are due to increases in white noise in the perceptual-motor system, were conducted. Young (20-29 years old) and old (60-69 and 70-79 years old) adults performed several perceptual-motor tasks. Older adults were progressively more variable in their performance outcome, but there was no age-related difference in white noise in the motor output. Older adults had a greater frequency-dependent structure in their motor variability that was associated with performance decrements. The findings challenge the main tenet of the neural noise hypothesis of aging in that the increased variability of older adults was due to a decreased ability to adapt to the constraints of the task rather than an increment of neural noise per se.

  5. Physical competition increases testosterone among Amazonian forager-horticulturalists: a test of the 'challenge hypothesis'.

    Science.gov (United States)

    Trumble, Benjamin C; Cummings, Daniel; von Rueden, Christopher; O'Connor, Kathleen A; Smith, Eric A; Gurven, Michael; Kaplan, Hillard

    2012-07-22

    The challenge hypothesis posits that acute increases in testosterone (T) during male-male competition enhance performance and survivability while limiting the physiological costs of consistently high T. Human challenge hypothesis research focuses on young men in industrial populations, who have higher baseline T levels than men in subsistence populations. We tested whether the Tsimane, pathogenically stressed forager-horticulturalists of the Bolivian Amazon, would express acute T increases in response to physical competition. Saliva was collected from 88 Tsimane men (aged 16-59 years) before and after a competitive soccer match. Tsimane men had significantly lower baseline levels of T (β = -0.41, p Tsimane males exhibit acute increases in T at the same relative magnitude reported by studies in industrialized settings, with larger increases in T for those who report better individual performance.

  6. A computationally efficient hypothesis testing method for epistasis analysis using multifactor dimensionality reduction.

    Science.gov (United States)

    Pattin, Kristine A; White, Bill C; Barney, Nate; Gui, Jiang; Nelson, Heather H; Kelsey, Karl T; Andrew, Angeline S; Karagas, Margaret R; Moore, Jason H

    2009-01-01

    Multifactor dimensionality reduction (MDR) was developed as a nonparametric and model-free data mining method for detecting, characterizing, and interpreting epistasis in the absence of significant main effects in genetic and epidemiologic studies of complex traits such as disease susceptibility. The goal of MDR is to change the representation of the data using a constructive induction algorithm to make nonadditive interactions easier to detect using any classification method such as naïve Bayes or logistic regression. Traditionally, MDR constructed variables have been evaluated with a naïve Bayes classifier that is combined with 10-fold cross validation to obtain an estimate of predictive accuracy or generalizability of epistasis models. Traditionally, we have used permutation testing to statistically evaluate the significance of models obtained through MDR. The advantage of permutation testing is that it controls for false positives due to multiple testing. The disadvantage is that permutation testing is computationally expensive. This is an important issue that arises in the context of detecting epistasis on a genome-wide scale. The goal of the present study was to develop and evaluate several alternatives to large-scale permutation testing for assessing the statistical significance of MDR models. Using data simulated from 70 different epistasis models, we compared the power and type I error rate of MDR using a 1,000-fold permutation test with hypothesis testing using an extreme value distribution (EVD). We find that this new hypothesis testing method provides a reasonable alternative to the computationally expensive 1,000-fold permutation test and is 50 times faster. We then demonstrate this new method by applying it to a genetic epidemiology study of bladder cancer susceptibility that was previously analyzed using MDR and assessed using a 1,000-fold permutation test.

  7. A General Class of Test Statistics for Van Valen's Red Queen Hypothesis.

    Science.gov (United States)

    Wiltshire, Jelani; Huffer, Fred W; Parker, William C

    2014-09-01

    Van Valen's Red Queen hypothesis states that within a homogeneous taxonomic group the age is statistically independent of the rate of extinction. The case of the Red Queen hypothesis being addressed here is when the homogeneous taxonomic group is a group of similar species. Since Van Valen's work, various statistical approaches have been used to address the relationship between taxon age and the rate of extinction. We propose a general class of test statistics that can be used to test for the effect of age on the rate of extinction. These test statistics allow for a varying background rate of extinction and attempt to remove the effects of other covariates when assessing the effect of age on extinction. No model is assumed for the covariate effects. Instead we control for covariate effects by pairing or grouping together similar species. Simulations are used to compare the power of the statistics. We apply the test statistics to data on Foram extinctions and find that age has a positive effect on the rate of extinction. A derivation of the null distribution of one of the test statistics is provided in the supplementary material.

  8. Hypothesis testing of matrix graph model with application to brain connectivity analysis.

    Science.gov (United States)

    Xia, Yin; Li, Lexin

    2017-09-01

    Brain connectivity analysis is now at the foreground of neuroscience research. A connectivity network is characterized by a graph, where nodes represent neural elements such as neurons and brain regions, and links represent statistical dependence that is often encoded in terms of partial correlation. Such a graph is inferred from the matrix-valued neuroimaging data such as electroencephalography and functional magnetic resonance imaging. There have been a good number of successful proposals for sparse precision matrix estimation under normal or matrix normal distribution; however, this family of solutions does not offer a direct statistical significance quantification for the estimated links. In this article, we adopt a matrix normal distribution framework and formulate the brain connectivity analysis as a precision matrix hypothesis testing problem. Based on the separable spatial-temporal dependence structure, we develop oracle and data-driven procedures to test both the global hypothesis that all spatial locations are conditionally independent, and simultaneous tests for identifying conditional dependent spatial locations with false discovery rate control. Our theoretical results show that the data-driven procedures perform asymptotically as well as the oracle procedures and enjoy certain optimality properties. The empirical finite-sample performance of the proposed tests is studied via intensive simulations, and the new tests are applied on a real electroencephalography data analysis. © 2016, The International Biometric Society.

  9. Phi index: a new metric to test the flush early and avoid the rush hypothesis.

    Directory of Open Access Journals (Sweden)

    Diogo S M Samia

    Full Text Available Optimal escape theory states that animals should counterbalance the costs and benefits of flight when escaping from a potential predator. However, in apparent contradiction with this well-established optimality model, birds and mammals generally initiate escape soon after beginning to monitor an approaching threat, a phenomena codified as the "Flush Early and Avoid the Rush" (FEAR hypothesis. Typically, the FEAR hypothesis is tested using correlational statistics and is supported when there is a strong relationship between the distance at which an individual first responds behaviorally to an approaching predator (alert distance, AD, and its flight initiation distance (the distance at which it flees the approaching predator, FID. However, such correlational statistics are both inadequate to analyze relationships constrained by an envelope (such as that in the AD-FID relationship and are sensitive to outliers with high leverage, which can lead one to erroneous conclusions. To overcome these statistical concerns we develop the phi index (Φ, a distribution-free metric to evaluate the goodness of fit of a 1:1 relationship in a constraint envelope (the prediction of the FEAR hypothesis. Using both simulation and empirical data, we conclude that Φ is superior to traditional correlational analyses because it explicitly tests the FEAR prediction, is robust to outliers, and it controls for the disproportionate influence of observations from large predictor values (caused by the constrained envelope in AD-FID relationship. Importantly, by analyzing the empirical data we corroborate the strong effect that alertness has on flight as stated by the FEAR hypothesis.

  10. The self: Your own worst enemy? A test of the self-invoking trigger hypothesis.

    Science.gov (United States)

    McKay, Brad; Wulf, Gabriele; Lewthwaite, Rebecca; Nordin, Andrew

    2015-01-01

    The self-invoking trigger hypothesis was proposed by Wulf and Lewthwaite [Wulf, G., & Lewthwaite, R. (2010). Effortless motor learning? An external focus of attention enhances movement effectiveness and efficiency. In B. Bruya (Ed.), Effortless attention: A new perspective in attention and action (pp. 75-101). Cambridge, MA: MIT Press] as a mechanism underlying the robust effect of attentional focus on motor learning and performance. One component of this hypothesis, relevant beyond the attentional focus effect, suggests that causing individuals to access their self-schema will negatively impact their learning and performance of a motor skill. The purpose of the present two studies was to provide an initial test of the performance and learning aspects of the self-invoking trigger hypothesis by asking participants in one group to think about themselves between trial blocks-presumably activating their self-schema-to compare their performance and learning to that of a control group. In Experiment 1, participants performed 2 blocks of 10 trials on a throwing task. In one condition, participants were asked between blocks to think about their past throwing experience. While a control group maintained their performance across blocks, the self group's performance was degraded on the second block. In Experiment 2, participants were asked to practice a wiffleball hitting task on two separate days. Participants returned on a third day to perform retention and transfer tests without the self-activating manipulation. Results indicated that the self group learned the hitting task less effectively than the control group. The findings reported here provide initial support for the self-invoking trigger hypothesis.

  11. Hypothesis testing on the fractal structure of behavioral sequences: the Bayesian assessment of scaling methodology.

    Science.gov (United States)

    Moscoso del Prado Martín, Fermín

    2013-12-01

    I introduce the Bayesian assessment of scaling (BAS), a simple but powerful Bayesian hypothesis contrast methodology that can be used to test hypotheses on the scaling regime exhibited by a sequence of behavioral data. Rather than comparing parametric models, as typically done in previous approaches, the BAS offers a direct, nonparametric way to test whether a time series exhibits fractal scaling. The BAS provides a simpler and faster test than do previous methods, and the code for making the required computations is provided. The method also enables testing of finely specified hypotheses on the scaling indices, something that was not possible with the previously available methods. I then present 4 simulation studies showing that the BAS methodology outperforms the other methods used in the psychological literature. I conclude with a discussion of methodological issues on fractal analyses in experimental psychology. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  12. Human skin-color sexual dimorphism: a test of the sexual selection hypothesis.

    Science.gov (United States)

    Madrigal, Lorena; Kelly, William

    2007-03-01

    Applied to skin color, the sexual selection hypothesis proposes that male preference for light-skinned females explains the presence of light skin in areas of low solar radiation. According to this proposal, in areas of high solar radiation, natural selection for dark skin overrides the universal preference of males for light females. But in areas in which natural selection ceases to act, sexual selection becomes more important, and causes human populations to become light-skinned, and females to be lighter than males. The sexual selection hypothesis proposes that human sexual dimorphism of skin color should be positively correlated with distance from the equator. We tested the prediction that sexual dimorphism should increase with increasing latitude, using adult-only data sets derived from measurements with standard reflectance spectrophotometric devices. Our analysis failed to support the prediction of a positive correlation between increasing distance from the equator and increased sexual dimorphism. We found no evidence in support of the sexual selection hypothesis. (c) 2006 Wiley-Liss, Inc.

  13. Acceptance sampling for attributes via hypothesis testing and the hypergeometric distribution

    Science.gov (United States)

    Samohyl, Robert Wayne

    2017-10-01

    This paper questions some aspects of attribute acceptance sampling in light of the original concepts of hypothesis testing from Neyman and Pearson (NP). Attribute acceptance sampling in industry, as developed by Dodge and Romig (DR), generally follows the international standards of ISO 2859, and similarly the Brazilian standards NBR 5425 to NBR 5427 and the United States Standards ANSI/ASQC Z1.4. The paper evaluates and extends the area of acceptance sampling in two directions. First, by suggesting the use of the hypergeometric distribution to calculate the parameters of sampling plans avoiding the unnecessary use of approximations such as the binomial or Poisson distributions. We show that, under usual conditions, discrepancies can be large. The conclusion is that the hypergeometric distribution, ubiquitously available in commonly used software, is more appropriate than other distributions for acceptance sampling. Second, and more importantly, we elaborate the theory of acceptance sampling in terms of hypothesis testing rigorously following the original concepts of NP. By offering a common theoretical structure, hypothesis testing from NP can produce a better understanding of applications even beyond the usual areas of industry and commerce such as public health and political polling. With the new procedures, both sample size and sample error can be reduced. What is unclear in traditional acceptance sampling is the necessity of linking the acceptable quality limit (AQL) exclusively to the producer and the lot quality percent defective (LTPD) exclusively to the consumer. In reality, the consumer should also be preoccupied with a value of AQL, as should the producer with LTPD. Furthermore, we can also question why type I error is always uniquely associated with the producer as producer risk, and likewise, the same question arises with consumer risk which is necessarily associated with type II error. The resolution of these questions is new to the literature. The

  14. A SIMPLE BUT EFFICIENT SCHEME FOR COLOUR IMAGE RETRIEVAL BASED ON STATISTICAL TESTS OF HYPOTHESIS

    Directory of Open Access Journals (Sweden)

    K. Seetharaman

    2011-02-01

    Full Text Available This paper proposes a simple but efficient scheme for colour image retrieval, based on statistical tests of hypothesis, namely test for equality of variance, test for equality of mean. The test for equality of variance is performed to test the similarity of the query and target images. If the images pass the test, then the test for equality of mean is performed on the same images to examine whether the two images have the same attributes / characteristics. If the query and target images pass the tests then it is inferred that the two images belong to the same class i.e. both the images are same; otherwise, it is assumed that the images belong to different classes i.e. both the images are different. The obtained test statistic values are indexed in ascending order and the image corresponding to the least value is identified as same / similar images. The proposed system is invariant for translation, scaling, and rotation, since the proposed system adjusts itself and treats either the query image or the target image is sample of other. The proposed scheme provides cent percent accuracy if the query and target images are same, whereas there is a slight variation for similar, transformed.

  15. Statistical power analysis a simple and general model for traditional and modern hypothesis tests

    CERN Document Server

    Murphy, Kevin R; Wolach, Allen

    2014-01-01

    Noted for its accessible approach, this text applies the latest approaches of power analysis to both null hypothesis and minimum-effect testing using the same basic unified model. Through the use of a few simple procedures and examples, the authors show readers with little expertise in statistical analysis how to obtain the values needed to carry out the power analysis for their research. Illustrations of how these analyses work and how they can be used to choose the appropriate criterion for defining statistically significant outcomes are sprinkled throughout. The book presents a simple and g

  16. Testing the null hypothesis of the nonexistence of a preseizure state

    International Nuclear Information System (INIS)

    Andrzejak, Ralph G.; Kraskov, Alexander; Mormann, Florian; Rieke, Christoph; Kreuz, Thomas; Elger, Christian E.; Lehnertz, Klaus

    2003-01-01

    A rapidly growing number of studies deals with the prediction of epileptic seizures. For this purpose, various techniques derived from linear and nonlinear time series analysis have been applied to the electroencephalogram of epilepsy patients. In none of these works, however, the performance of the seizure prediction statistics is tested against a null hypothesis, an otherwise ubiquitous concept in science. In consequence, the evaluation of the reported performance values is problematic. Here, we propose the technique of seizure time surrogates based on a Monte Carlo simulation to remedy this deficit

  17. Convergence Hypothesis: Evidence from Panel Unit Root Test with Spatial Dependence

    Directory of Open Access Journals (Sweden)

    Lezheng Liu

    2006-10-01

    Full Text Available In this paper we test the convergence hypothesis by using a revised 4- step procedure of panel unit root test suggested by Evans and Karras (1996. We use data on output for 24 OECD countries over 40 years long. Whether the convergence, if any, is conditional or absolute is also examined. According to a proposition by Baltagi, Bresson, and Pirotte (2005, we incorporate spatial autoregressive error into a fixedeffect panel model to account for not only the heterogeneous panel structure, but also spatial dependence, which might induce lower statistical power of conventional panel unit root test. Our empirical results indicate that output is converging among OECD countries. However, convergence is characterized as conditional. The results also report a relatively lower convergent speed compared to conventional panel studies.

  18. Hypothesis testing and power calculations for taxonomic-based human microbiome data.

    Science.gov (United States)

    La Rosa, Patricio S; Brooks, J Paul; Deych, Elena; Boone, Edward L; Edwards, David J; Wang, Qin; Sodergren, Erica; Weinstock, George; Shannon, William D

    2012-01-01

    This paper presents new biostatistical methods for the analysis of microbiome data based on a fully parametric approach using all the data. The Dirichlet-multinomial distribution allows the analyst to calculate power and sample sizes for experimental design, perform tests of hypotheses (e.g., compare microbiomes across groups), and to estimate parameters describing microbiome properties. The use of a fully parametric model for these data has the benefit over alternative non-parametric approaches such as bootstrapping and permutation testing, in that this model is able to retain more information contained in the data. This paper details the statistical approaches for several tests of hypothesis and power/sample size calculations, and applies them for illustration to taxonomic abundance distribution and rank abundance distribution data using HMP Jumpstart data on 24 subjects for saliva, subgingival, and supragingival samples. Software for running these analyses is available.

  19. Hypothesis to Explain the Size Effect Observed in APO-BMI Compression Tests

    Energy Technology Data Exchange (ETDEWEB)

    Schembri, Philip Edward [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Siranosian, Antranik Antonio [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kingston, Lance Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-01-07

    In 2013 compression tests were performed on cylindrical specimens of carbon-microballoon-APOBMI syntactic foam machined to different lengths (0.25, 0.5, and 2.8 inches1) (Kingston, 2013). In 2014 similar tests were performed on glass-microballoon-APO-BMI of different lengths (~0.15”, ~0.32”, and ~0.57”). In all these tests it was observed that, when strains were calculated from the platen displacement (corrected for machine compliance), the apparent Young’s modulus of the material decreased with specimen size, as shown in Table 1. The reason for this size effect was speculated to be a layer of damage on or near the top and bottom machined surfaces of the specimens (Kingston, Schembri, & Siranosian, 2014). This report examines that hypothesis in further detail.

  20. Hypothesis testing and power calculations for taxonomic-based human microbiome data.

    Directory of Open Access Journals (Sweden)

    Patricio S La Rosa

    Full Text Available This paper presents new biostatistical methods for the analysis of microbiome data based on a fully parametric approach using all the data. The Dirichlet-multinomial distribution allows the analyst to calculate power and sample sizes for experimental design, perform tests of hypotheses (e.g., compare microbiomes across groups, and to estimate parameters describing microbiome properties. The use of a fully parametric model for these data has the benefit over alternative non-parametric approaches such as bootstrapping and permutation testing, in that this model is able to retain more information contained in the data. This paper details the statistical approaches for several tests of hypothesis and power/sample size calculations, and applies them for illustration to taxonomic abundance distribution and rank abundance distribution data using HMP Jumpstart data on 24 subjects for saliva, subgingival, and supragingival samples. Software for running these analyses is available.

  1. The recognition signal hypothesis for the adaptive evolution of religion : a phylogenetic test with Christian denominations.

    Science.gov (United States)

    Matthews, Luke J

    2012-06-01

    Recent research on the evolution of religion has focused on whether religion is an unselected by-product of evolutionary processes or if it is instead an adaptation by natural selection. Adaptive hypotheses for religion include direct fitness benefits from improved health and indirect fitness benefits mediated by costly signals and/or cultural group selection. Herein, I propose that religious denominations achieve indirect fitness gains for members through the use of ecologically arbitrary beliefs, rituals, and moral rules that function as recognition markers of cultural inheritance analogous to kin and species recognition of genetic inheritance in biology. This recognition signal hypotheses could act in concert with either costly signaling or cultural group selection to produce evolutionarily altruistic behaviors within denominations. Using a cultural phylogenetic analysis, I show that a large set of religious behaviors among extant Christian denominations supports the prediction of the recognition signal hypothesis that characters change more frequently near historical schisms. By incorporating demographic data into the model, I show that more-distinctive denominations, as measured through dissimilar characteristics, appear to be protected from intrusion by nonmembers in mixed-denomination households, and that they may be experiencing greater biological growth of their populations even in the present day.

  2. Biological substrates of reward and aversion: a nucleus accumbens activity hypothesis.

    Science.gov (United States)

    Carlezon, William A; Thomas, Mark J

    2009-01-01

    The nucleus accumbens (NAc) is a critical element of the mesocorticolimbic system, a brain circuit implicated in reward and motivation. This basal forebrain structure receives dopamine (DA) input from the ventral tegmental area (VTA) and glutamate (GLU) input from regions including the prefrontal cortex (PFC), amygdala (AMG), and hippocampus (HIP). As such, it integrates inputs from limbic and cortical regions, linking motivation with action. The NAc has a well-established role in mediating the rewarding effects of drugs of abuse and natural rewards such as food and sexual behavior. However, accumulating pharmacological, molecular, and electrophysiological evidence has raised the possibility that it also plays an important (and sometimes underappreciated) role in mediating aversive states. Here we review evidence that rewarding and aversive states are encoded in the activity of NAc medium spiny GABAergic neurons, which account for the vast majority of the neurons in this region. While admittedly simple, this working hypothesis is testable using combinations of available and emerging technologies, including electrophysiology, genetic engineering, and functional brain imaging. A deeper understanding of the basic neurobiology of mood states will facilitate the development of well-tolerated medications that treat and prevent addiction and other conditions (e.g., mood disorders) associated with dysregulation of brain motivation systems.

  3. Test of an Hypothesis of Magnetization, Tilt and Flow in an Hypabyssal Intrusion, Colombian Andes

    Science.gov (United States)

    Muggleton, S.; MacDonald, W. D.; Estrada, J. J.; Sierra, G. M.

    2002-05-01

    Magnetic remanence in the Miocene Clavijo intrusion in the Cauca Valley, adjacent to the Cordillera Central, plunges steeply northward (MacDonald et al., 1996). Assuming magnetization in a normal magnetic field, the expected remanence direction is approximately I= 10o, D= 000o; the observed remanence is I=84o, D=003o. The discrepancy could be explained by a 74o rotation about a horizontal E-W axis, i.e., about an axis normal to the nearby N-S trending Romeral fault zone. If the intrusion is the shallow feeder of a now-eroded andesitic volcano, then perhaps the paleovertical direction is preserved in flow lineations and provides a test of the tilt/rotation of the remanence. In combination, the steep remanence direction, vertical flow, and the inferred rotation of the volcanic neck lead to the hypothesis of a shallow-plunging southward lineation for this body. Using anisotropy of magnetic susceptibility (AMS) as a proxy for the flow lineation, it is predicted that the K1 (maximum susceptibility) axis in this body plunges gently south. This hypothesis was tested using approximately 50 oriented cores from 5 sites near the west margin of the Clavijo intrusion. The results suggest a NW plunging lineation, inconsistent with the initial hypothesis. However, a relatively consistent flow lineation is suggested by the K1 axes. If this flow axis represents paleovertical, it suggests moderate tilting of the Clavijo body towards the southeast. The results are encouraging enough to suggest that AMS may be useful for determining paleo-vertical in shallow volcanic necks and hypabyssal intrusions, and might ultimately be useful in a tilt-correction for such bodies. Other implications of the results will be discussed. MacDonald, WD, Estrada, JJ, Sierra, GM, Gonzalez, H, 1996, Late Cenozoic tectonics and paleomagnetism of North Cauca Basin intrusions, Colombian Andes: Dual rotation modes: Tectonophysics, v 261, p. 277-289.

  4. Testing the EKC hypothesis by considering trade openness, urbanization, and financial development: the case of Turkey.

    Science.gov (United States)

    Ozatac, Nesrin; Gokmenoglu, Korhan K; Taspinar, Nigar

    2017-07-01

    This study investigates the environmental Kuznets curve (EKC) hypothesis for the case of Turkey from 1960 to 2013 by considering energy consumption, trade, urbanization, and financial development variables. Although previous literature examines various aspects of the EKC hypothesis for the case of Turkey, our model augments the basic model with several covariates to develop a better understanding of the relationship among the variables and to refrain from omitted variable bias. The results of the bounds test and the error correction model under autoregressive distributed lag mechanism suggest long-run relationships among the variables as well as proof of the EKC and the scale effect in Turkey. A conditional Granger causality test reveals that there are causal relationships among the variables. Our findings can have policy implications including the imposition of a "polluter pays" mechanism, such as the implementation of a carbon tax for pollution trading, to raise the urban population's awareness about the importance of adopting renewable energy and to support clean, environmentally friendly technology.

  5. Recurrence network measures for hypothesis testing using surrogate data: Application to black hole light curves

    Science.gov (United States)

    Jacob, Rinku; Harikrishnan, K. P.; Misra, R.; Ambika, G.

    2018-01-01

    Recurrence networks and the associated statistical measures have become important tools in the analysis of time series data. In this work, we test how effective the recurrence network measures are in analyzing real world data involving two main types of noise, white noise and colored noise. We use two prominent network measures as discriminating statistic for hypothesis testing using surrogate data for a specific null hypothesis that the data is derived from a linear stochastic process. We show that the characteristic path length is especially efficient as a discriminating measure with the conclusions reasonably accurate even with limited number of data points in the time series. We also highlight an additional advantage of the network approach in identifying the dimensionality of the system underlying the time series through a convergence measure derived from the probability distribution of the local clustering coefficients. As examples of real world data, we use the light curves from a prominent black hole system and show that a combined analysis using three primary network measures can provide vital information regarding the nature of temporal variability of light curves from different spectroscopic classes.

  6. Binary Hypothesis Testing With Byzantine Sensors: Fundamental Tradeoff Between Security and Efficiency

    Science.gov (United States)

    Ren, Xiaoqiang; Yan, Jiaqi; Mo, Yilin

    2018-03-01

    This paper studies binary hypothesis testing based on measurements from a set of sensors, a subset of which can be compromised by an attacker. The measurements from a compromised sensor can be manipulated arbitrarily by the adversary. The asymptotic exponential rate, with which the probability of error goes to zero, is adopted to indicate the detection performance of a detector. In practice, we expect the attack on sensors to be sporadic, and therefore the system may operate with all the sensors being benign for extended period of time. This motivates us to consider the trade-off between the detection performance of a detector, i.e., the probability of error, when the attacker is absent (defined as efficiency) and the worst-case detection performance when the attacker is present (defined as security). We first provide the fundamental limits of this trade-off, and then propose a detection strategy that achieves these limits. We then consider a special case, where there is no trade-off between security and efficiency. In other words, our detection strategy can achieve the maximal efficiency and the maximal security simultaneously. Two extensions of the secure hypothesis testing problem are also studied and fundamental limits and achievability results are provided: 1) a subset of sensors, namely "secure" sensors, are assumed to be equipped with better security countermeasures and hence are guaranteed to be benign, 2) detection performance with unknown number of compromised sensors. Numerical examples are given to illustrate the main results.

  7. Chemotherapy curable malignancies and cancer stem cells: a biological review and hypothesis.

    Science.gov (United States)

    Savage, Philip

    2016-11-21

    Cytotoxic chemotherapy brings routine cures to only a small select group of metastatic malignancies comprising gestational trophoblast tumours, germ cell tumours, acute leukemia, Hodgkin's disease, high grade lymphomas and some of the rare childhood malignancies. We have previously postulated that the extreme sensitivity to chemotherapy for these malignancies is linked to the on-going high levels of apoptotic sensitivity that is naturally linked with the unique genetic events of nuclear fusion, meiosis, VDJ recombination, somatic hypermutation, and gastrulation that have occurred within the cells of origin of these malignancies. In this review we will examine the cancer stem cell/cancer cell relationship of each of the chemotherapy curable malignancies and how this relationship impacts on the resultant biology and pro-apoptotic sensitivity of the varying cancer cell types. In contrast to the common epithelial cancers, in each of the chemotherapy curable malignancies there are no conventional hierarchical cancer stem cells. However cells with cancer stem like qualities can arise stochastically from within the general tumour cell population. These stochastic stem cells acquire a degree of resistance to DNA damaging agents but also retain much of the key characteristics of the cancer cells from which they develop. We would argue that the balance between the acquired resistance of the stochastic cancer stem cell and the inherent chemotherapy sensitivity of parent tumour cell determines the overall chemotherapy curability of each diagnosis. The cancer stem cells in the chemotherapy curable malignancies appear to have two key biological differences from those of the more common chemotherapy incurable malignancies. The first difference is that the conventional hierarchical pattern of cancer stem cells is absent in each of the chemotherapy curable malignancies. The other key difference, we suggest, is that the stochastic stem cells in the chemotherapy curable malignancies

  8. Testing the niche-breadth-range-size hypothesis: habitat specialization vs. performance in Australian alpine daisies.

    Science.gov (United States)

    Hirst, Megan J; Griffin, Philippa C; Sexton, Jason P; Hoffmann, Ary A

    2017-10-01

    Relatively common species within a clade are expected to perform well across a wider range of conditions than their rarer relatives, yet experimental tests of this "niche-breadth-range-size" hypothesis remain surprisingly scarce. Rarity may arise due to trade-offs between specialization and performance across a wide range of environments. Here we use common garden and reciprocal transplant experiments to test the niche-breadth-range-size hypothesis, focusing on four common and three rare endemic alpine daisies (Brachyscome spp.) from the Australian Alps. We used three experimental contexts: (1) alpine reciprocal seedling experiment, a test of seedling survival and growth in three alpine habitat types differing in environmental quality and species diversity; (2) warm environment common garden, a test of whether common daisy species have higher growth rates and phenotypic plasticity, assessed in a common garden in a warmer climate and run simultaneously with experiment 1; and (3) alpine reciprocal seed experiment, a test of seed germination capacity and viability in the same three alpine habitat types as in experiment 1. In the alpine reciprocal seedling experiment, survival of all species was highest in the open heathland habitat where overall plant diversity is high, suggesting a general, positive response to a relatively productive, low-stress environment. We found only partial support for higher survival of rare species in their habitats of origin. In the warm environment common garden, three common daisies exhibited greater growth and biomass than two rare species, but the other rare species performed as well as the common species. In the alpine reciprocal seed experiment, common daisies exhibited higher germination across most habitats, but rare species maintained a higher proportion of viable seed in all conditions, suggesting different life history strategies. These results indicate that some but not all rare, alpine endemics exhibit stress tolerance at the

  9. Diversity Generator Mechanisms Are Essential Components of Biological Systems: The Two Queen Hypothesis

    Directory of Open Access Journals (Sweden)

    Eric Muraille

    2018-02-01

    Full Text Available Diversity is widely known to fuel adaptation and evolutionary processes and increase robustness at the population, species and ecosystem levels. The Neo-Darwinian paradigm proposes that the diversity of biological entities is the consequence of genetic changes arising spontaneously and randomly, without regard for their usefulness. However, a growing body of evidence demonstrates that the evolutionary process has shaped mechanisms, such as horizontal gene transfer mechanisms, meiosis and the adaptive immune system, which has resulted in the regulated generation of diversity among populations. Though their origins are unrelated, these diversity generator (DG mechanisms share common functional properties. They (i contribute to the great unpredictability of the composition and/or behavior of biological systems, (ii favor robustness and collectivism among populations and (iii operate mainly by manipulating the systems that control the interaction of living beings with their environment. The definition proposed here for DGs is based on these properties and can be used to identify them according to function. Interestingly, prokaryotic DGs appear to be mainly reactive, as they generate diversity in response to environmental stress. They are involved in the widely described Red Queen/arms race/Cairnsian dynamic. The emergence of multicellular organisms harboring K selection traits (longer reproductive life cycle and smaller population size has led to the acquisition of a new class of DGs that act anticipatively to stress pressures and generate a distinct dynamic called the “White Queen” here. The existence of DGs leads to the view of evolution as a more “intelligent” and Lamarckian-like process. Their repeated selection during evolution could be a neglected example of convergent evolution and suggests that some parts of the evolutionary process are tightly constrained by ecological factors, such as the population size, the generation time and

  10. Diversity Generator Mechanisms Are Essential Components of Biological Systems: The Two Queen Hypothesis.

    Science.gov (United States)

    Muraille, Eric

    2018-01-01

    Diversity is widely known to fuel adaptation and evolutionary processes and increase robustness at the population, species and ecosystem levels. The Neo-Darwinian paradigm proposes that the diversity of biological entities is the consequence of genetic changes arising spontaneously and randomly, without regard for their usefulness. However, a growing body of evidence demonstrates that the evolutionary process has shaped mechanisms, such as horizontal gene transfer mechanisms, meiosis and the adaptive immune system, which has resulted in the regulated generation of diversity among populations. Though their origins are unrelated, these diversity generator (DG) mechanisms share common functional properties. They (i) contribute to the great unpredictability of the composition and/or behavior of biological systems, (ii) favor robustness and collectivism among populations and (iii) operate mainly by manipulating the systems that control the interaction of living beings with their environment. The definition proposed here for DGs is based on these properties and can be used to identify them according to function. Interestingly, prokaryotic DGs appear to be mainly reactive, as they generate diversity in response to environmental stress. They are involved in the widely described Red Queen/arms race/Cairnsian dynamic. The emergence of multicellular organisms harboring K selection traits (longer reproductive life cycle and smaller population size) has led to the acquisition of a new class of DGs that act anticipatively to stress pressures and generate a distinct dynamic called the "White Queen" here. The existence of DGs leads to the view of evolution as a more "intelligent" and Lamarckian-like process. Their repeated selection during evolution could be a neglected example of convergent evolution and suggests that some parts of the evolutionary process are tightly constrained by ecological factors, such as the population size, the generation time and the intensity of

  11. TEST OF THE CATCH-UP HYPOTHESIS IN AFRICAN AGRICULTURAL GROWTH RATES

    Directory of Open Access Journals (Sweden)

    Kalu Ukpai IFEGWU

    2015-11-01

    Full Text Available The paper tested the catch-up hypothesis in agricultural growth rates of twenty-six African countries. Panel data used was drawn from the Food and Agricultural Organization Statistics (FAOSTAT of the United Nations. The Data Envelopment Analysis Method for measuring productivity was used to estimate productivity growth rates. The cross-section framework consisting of sigma-convergence and beta-convergence was employed to test the catching up process. Catching up is said to exist if the value of beta is negative and significant. Since catching up does not necessarily imply narrowing of national productivity inequalities, sigma-convergence which measures inequality, was estimated for the same variables. The results showed evidence of the catch-up process, but failed to find a narrowing of productivity inequalities among countries.

  12. Use of supernovae light curves for testing the expansion hypothesis and other cosmological relations

    International Nuclear Information System (INIS)

    Rust, B.W.

    1974-01-01

    This thesis is primarily concerned with a test of the expansion hypothesis based on the relation Δt/sub obs/ = (1 + V/sub r//c)Δt/sub int/ where Δt/sub int/ is the time lapse characterizing some phenomenon in a distant galaxy, Δt/sub obs/ is the observed time lapse and V/sub r/ is the symbolic velocity of recession. If the red shift is a Doppler effect, the observed time lapse should be lengthened by the same factor as the wave length of the light. Many authors have suggested type I supernovae for such a test because of their great luminosity and the uniformity of their light curves, but apparently the test has heretofore never actually been performed. Thirty-six light curves were gathered from the literature and one (SN1971i) was measured. All of the light curves were reduced to a common (m/sub pg/) photometric system. The comparison time lapse, Δt/sub c/, was taken to be the time required for the brightness to fall from 0.5 m below peak to 2.5 m below peak. The straight line regression of Δt/sub c/ on V/sub r/ gives a correlation coefficient significant at the 93 percent level, and the simple static Euclidean hypothesis is rejected at that level. The regression line also deviates from the prediction of the classical expansion hypothesis. Better agreement was obtained using the chronogeometric theory of I. E. Segal ( []972 Astron. and Astrophys. 18, 143), but the scatter in the present data makes it impossible to distinguish between these alternate hypotheses at the 95 percent confidence level. The question of how many additional light curves would be needed to give definite tests is addressed. It is shown that at the present rate of supernova discoveries, only a few more years would be required to obtain the necessary data if light curves are systematically measured for the more distant supernovae. (Diss. Abstr. Int., B)

  13. Biorhythms, deciduous enamel thickness, and primary bone growth in modern human children: a test of the Havers-Halberg Oscillation hypothesis

    OpenAIRE

    Mahoney, Patrick; Miszkiewicz, Justyna J.; Pitfield, Rosie; Schlecht, Stephen H.; Deter, Chris; Guatelli-Steinberg, Debbie

    2016-01-01

    Across mammalian species, the periodicity with which enamel layers form (Retzius periodicity) in permanent teeth corresponds with average body mass and the pace of life history. According to the Havers-Halberg Oscillation hypothesis (HHO), Retzius periodicity (RP) is a manifestation of a biorhythm that is also expressed in lamellar bone. Potentially, these links provide a basis for investigating aspects of a species’ biology from fossilized teeth. Here, we tested intra-specific predictions of...

  14. Probability-informed testing for reliability assurance through Bayesian hypothesis methods

    International Nuclear Information System (INIS)

    Smith, Curtis; Kelly, Dana; Dezfuli, Homayoon

    2010-01-01

    Bayesian inference techniques play a central role in modern risk and reliability evaluations of complex engineering systems. These techniques allow the system performance data and any relevant associated information to be used collectively to calculate the probabilities of various types of hypotheses that are formulated as part of reliability assurance activities. This paper proposes a methodology based on Bayesian hypothesis testing to determine the number of tests that would be required to demonstrate that a system-level reliability target is met with a specified probability level. Recognizing that full-scale testing of a complex system is often not practical, testing schemes are developed at the subsystem level to achieve the overall system reliability target. The approach uses network modeling techniques to transform the topology of the system into logic structures consisting of series and parallel subsystems. The paper addresses the consideration of cost in devising subsystem level test schemes. The developed techniques are demonstrated using several examples. All analyses are carried out using the Bayesian analysis tool WinBUGS, which uses Markov chain Monte Carlo simulation methods to carry out inference over the network.

  15. A test of the thermal melanism hypothesis in the wingless grasshopper Phaulacridium vittatum.

    Science.gov (United States)

    Harris, Rebecca M; McQuillan, Peter; Hughes, Lesley

    2013-01-01

    Altitudinal clines in melanism are generally assumed to reflect the fitness benefits resulting from thermal differences between colour morphs, yet differences in thermal quality are not always discernible. The intra-specific application of the thermal melanism hypothesis was tested in the wingless grasshopper Phaulacridium vittatum (Sjöstedt) (Orthoptera: Acrididae) first by measuring the thermal properties of the different colour morphs in the laboratory, and second by testing for differences in average reflectance and spectral characteristics of populations along 14 altitudinal gradients. Correlations between reflectance, body size, and climatic variables were also tested to investigate the underlying causes of clines in melanism. Melanism in P. vittatum represents a gradation in colour rather than distinct colour morphs, with reflectance ranging from 2.49 to 5.65%. In unstriped grasshoppers, darker morphs warmed more rapidly than lighter morphs and reached a higher maximum temperature (lower temperature excess). In contrast, significant differences in thermal quality were not found between the colour morphs of striped grasshoppers. In support of the thermal melanism hypothesis, grasshoppers were, on average, darker at higher altitudes, there were differences in the spectral properties of brightness and chroma between high and low altitudes, and temperature variables were significant influences on the average reflectance of female grasshoppers. However, altitudinal gradients do not represent predictable variation in temperature, and the relationship between melanism and altitude was not consistent across all gradients. Grasshoppers generally became darker at altitudes above 800 m a.s.l., but on several gradients reflectance declined with altitude and then increased at the highest altitude.

  16. A Test of the Thermal Melanism Hypothesis in the Wingless Grasshopper Phaulacridium vittatum

    Science.gov (United States)

    Harris, Rebecca M.; McQuillan, Peter; Hughes, Lesley

    2013-01-01

    Altitudinal clines in melanism are generally assumed to reflect the fitness benefits resulting from thermal differences between colour morphs, yet differences in thermal quality are not always discernible. The intra-specific application of the thermal melanism hypothesis was tested in the wingless grasshopper Phaulacridium vittatum (Sjöstedt) (Orthoptera: Acrididae) first by measuring the thermal properties of the different colour morphs in the laboratory, and second by testing for differences in average reflectance and spectral characteristics of populations along 14 altitudinal gradients. Correlations between reflectance, body size, and climatic variables were also tested to investigate the underlying causes of clines in melanism. Melanism in P. vittatum represents a gradation in colour rather than distinct colour morphs, with reflectance ranging from 2.49 to 5.65%. In unstriped grasshoppers, darker morphs warmed more rapidly than lighter morphs and reached a higher maximum temperature (lower temperature excess). In contrast, significant differences in thermal quality were not found between the colour morphs of striped grasshoppers. In support of the thermal melanism hypothesis, grasshoppers were, on average, darker at higher altitudes, there were differences in the spectral properties of brightness and chroma between high and low altitudes, and temperature variables were significant influences on the average reflectance of female grasshoppers. However, altitudinal gradients do not represent predictable variation in temperature, and the relationship between melanism and altitude was not consistent across all gradients. Grasshoppers generally became darker at altitudes above 800 m a.s.l., but on several gradients reflectance declined with altitude and then increased at the highest altitude. PMID:23909454

  17. Generalist predator, cyclic voles and cavity nests: testing the alternative prey hypothesis.

    Science.gov (United States)

    Pöysä, Hannu; Jalava, Kaisa; Paasivaara, Antti

    2016-12-01

    The alternative prey hypothesis (APH) states that when the density of the main prey declines, generalist predators switch to alternative prey and vice versa, meaning that predation pressure on the alternative prey should be negatively correlated with the density of the main prey. We tested the APH in a system comprising one generalist predator (pine marten, Martes martes), cyclic main prey (microtine voles, Microtus agrestis and Myodes glareolus) and alternative prey (cavity nests of common goldeneye, Bucephala clangula); pine marten is an important predator of both voles and common goldeneye nests. Specifically, we studied whether annual predation rate of real common goldeneye nests and experimental nests is negatively associated with fluctuation in the density of voles in four study areas in southern Finland in 2000-2011. Both vole density and nest predation rate varied considerably between years in all study areas. However, we did not find support for the hypothesis that vole dynamics indirectly affects predation rate of cavity nests in the way predicted by the APH. On the contrary, the probability of predation increased with vole spring abundance for both real and experimental nests. Furthermore, a crash in vole abundance from previous autumn to spring did not increase the probability of predation of real nests, although it increased that of experimental nests. We suggest that learned predation by pine marten individuals, coupled with efficient search image for cavities, overrides possible indirect positive effects of high vole density on the alternative prey in our study system.

  18. TESTS OF THE PLANETARY HYPOTHESIS FOR PTFO 8-8695b

    International Nuclear Information System (INIS)

    Yu, Liang; Winn, Joshua N.; Rappaport, Saul; Dai, Fei; Triaud, Amaury H. M. J.; Gillon, Michaël; Delrez, Laetitia; Jehin, Emmanuel; Lendl, Monika; Albrecht, Simon; Bieryla, Allyson; Holman, Matthew J.; Montet, Benjamin T.; Hillenbrand, Lynne; Howard, Andrew W.; Huang, Chelsea X.; Isaacson, Howard; Sanchis-Ojeda, Roberto; Muirhead, Philip

    2015-01-01

    The T Tauri star PTFO 8-8695 exhibits periodic fading events that have been interpreted as the transits of a giant planet on a precessing orbit. Here we present three tests of the planet hypothesis. First, we sought evidence for the secular changes in light-curve morphology that are predicted to be a consequence of orbital precession. We observed 28 fading events spread over several years and did not see the expected changes. Instead, we found that the fading events are not strictly periodic. Second, we attempted to detect the planet's radiation, based on infrared observations spanning the predicted times of occultations. We ruled out a signal of the expected amplitude. Third, we attempted to detect the Rossiter–McLaughlin effect by performing high-resolution spectroscopy throughout a fading event. No effect was seen at the expected level, ruling out most (but not all) possible orientations for the hypothetical planetary orbit. Our spectroscopy also revealed strong, time-variable, high-velocity Hα and Ca H and K emission features. All these observations cast doubt on the planetary hypothesis, and suggest instead that the fading events represent starspots, eclipses by circumstellar dust, or occultations of an accretion hotspot

  19. A test of the symbol interdependency hypothesis with both concrete and abstract stimuli.

    Science.gov (United States)

    Malhi, Simritpal Kaur; Buchanan, Lori

    2018-01-01

    In Experiment 1, the symbol interdependency hypothesis was tested with both concrete and abstract stimuli. Symbolic (i.e., semantic neighbourhood distance) and embodied (i.e., iconicity) factors were manipulated in two tasks-one that tapped symbolic relations (i.e., semantic relatedness judgment) and another that tapped embodied relations (i.e., iconicity judgment). Results supported the symbol interdependency hypothesis in that the symbolic factor was recruited for the semantic relatedness task and the embodied factor was recruited for the iconicity task. Across tasks, and especially in the iconicity task, abstract stimuli resulted in shorter RTs. This finding was in contrast to the concreteness effect where concrete words result in shorter RTs. Experiment 2 followed up on this finding by replicating the iconicity task from Experiment 1 in an ERP paradigm. Behavioural results continued to show a reverse concreteness effect with shorter RTs for abstract stimuli. However, ERP results paralleled the N400 and anterior N700 concreteness effects found in the literature, with more negative amplitudes for concrete stimuli.

  20. A test of the symbol interdependency hypothesis with both concrete and abstract stimuli

    Science.gov (United States)

    Buchanan, Lori

    2018-01-01

    In Experiment 1, the symbol interdependency hypothesis was tested with both concrete and abstract stimuli. Symbolic (i.e., semantic neighbourhood distance) and embodied (i.e., iconicity) factors were manipulated in two tasks—one that tapped symbolic relations (i.e., semantic relatedness judgment) and another that tapped embodied relations (i.e., iconicity judgment). Results supported the symbol interdependency hypothesis in that the symbolic factor was recruited for the semantic relatedness task and the embodied factor was recruited for the iconicity task. Across tasks, and especially in the iconicity task, abstract stimuli resulted in shorter RTs. This finding was in contrast to the concreteness effect where concrete words result in shorter RTs. Experiment 2 followed up on this finding by replicating the iconicity task from Experiment 1 in an ERP paradigm. Behavioural results continued to show a reverse concreteness effect with shorter RTs for abstract stimuli. However, ERP results paralleled the N400 and anterior N700 concreteness effects found in the literature, with more negative amplitudes for concrete stimuli. PMID:29590121

  1. Gratitude facilitates private conformity: A test of the social alignment hypothesis.

    Science.gov (United States)

    Ng, Jomel W X; Tong, Eddie M W; Sim, Dael L Y; Teo, Samantha W Y; Loy, Xingqi; Giesbrecht, Timo

    2017-03-01

    Past research has established clear support for the prosocial function of gratitude in improving the well-being of others. The present research provides evidence for another hypothesized function of gratitude: the social alignment function, which enhances the tendency of grateful individuals to follow social norms. We tested the social alignment hypothesis of gratitude in 2 studies with large samples. Using 2 different conformity paradigms, participants were subjected to a color judgment task (Experiment 1) and a material consumption task (Experiment 2). They were provided with information showing choices allegedly made by others, but were allowed to state their responses in private. Supporting the social alignment hypothesis, the results showed that induced gratitude increased private conformity. Specifically, participants induced to feel gratitude were more likely to conform to the purportedly popular choice, even if the option was factually incorrect (Experiment 1). This effect appears to be specific to gratitude; induction of joy produced significantly less conformity than gratitude (Experiment 2). We discuss whether the social alignment function provides a behavioral pathway in the role of gratitude in building social relationships. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  2. Testing a hypothesis of unidirectional hybridization in plants: Observations on Sonneratia, Bruguiera and Ligularia

    Directory of Open Access Journals (Sweden)

    Wu Chung-I

    2008-05-01

    Full Text Available Abstract Background When natural hybridization occurs at sites where the hybridizing species differ in abundance, the pollen load delivered to the rare species should be predominantly from the common species. Previous authors have therefore proposed a hypothesis on the direction of hybridization: interspecific hybrids are more likely to have the female parent from the rare species and the male parent from the common species. We wish to test this hypothesis using data of plant hybridizations both from our own experimentation and from the literature. Results By examining the maternally inherited chloroplast DNA of 6 cases of F1 hybridization from four genera of plants, we infer unidirectional hybridization in most cases. In all 5 cases where the relative abundance of the parental species deviates from parity, however, the direction is predominantly in the direction opposite of the prediction based strictly on numerical abundance. Conclusion Our results show that the observed direction of hybridization is almost always opposite of the predicted direction based on the relative abundance of the hybridizing species. Several alternative hypotheses, including unidirectional postmating isolation and reinforcement of premating isolation, were discussed.

  3. A web-portal for interactive data exploration, visualization, and hypothesis testing.

    Science.gov (United States)

    Bartsch, Hauke; Thompson, Wesley K; Jernigan, Terry L; Dale, Anders M

    2014-01-01

    Clinical research studies generate data that need to be shared and statistically analyzed by their participating institutions. The distributed nature of research and the different domains involved present major challenges to data sharing, exploration, and visualization. The Data Portal infrastructure was developed to support ongoing research in the areas of neurocognition, imaging, and genetics. Researchers benefit from the integration of data sources across domains, the explicit representation of knowledge from domain experts, and user interfaces providing convenient access to project specific data resources and algorithms. The system provides an interactive approach to statistical analysis, data mining, and hypothesis testing over the lifetime of a study and fulfills a mandate of public sharing by integrating data sharing into a system built for active data exploration. The web-based platform removes barriers for research and supports the ongoing exploration of data.

  4. Testing the Cuckoldry Risk Hypothesis of Partner Sexual Coercion in Community and Forensic Samples

    Directory of Open Access Journals (Sweden)

    Joseph A. Camilleri

    2009-04-01

    Full Text Available Evolutionary theory has informed the investigation of male sexual coercion but has seldom been applied to the analysis of sexual coercion within established couples. The cuckoldry risk hypothesis, that sexual coercion is a male tactic used to reduce the risk of extrapair paternity, was tested in two studies. In a community sample, indirect cues of infidelity predicted male propensity for sexual coaxing in the relationship, and direct cues predicted propensity for sexual coercion. In the forensic sample, we found that most partner rapists experienced cuckoldry risk prior to committing their offence and experienced more types of cuckoldry risk events than non-sexual partner assaulters. These findings suggest that cuckoldry risk influences male sexual coercion in established sexual relationships.

  5. Psychopathic traits and preattentive threat processing in children: a novel test of the fearlessness hypothesis.

    Science.gov (United States)

    Sylvers, Patrick D; Brennan, Patricia A; Lilienfeld, Scott O

    2011-10-01

    We tested the fearlessness hypothesis of psychopathy in an at-risk sample of 88 preadolescent children. Psychopathy was measured using combined child- and parent-reported scores on the Antisocial Process Screening Device (APSD). Using a continuous-flash-suppression paradigm, we evaluated threat processing at the preattentive level for the first time in a study of psychopathy. Scores for the APSD Callous/Unemotional factor, which assesses the core affective deficits of psychopathy, predicted preattentive face-recognition deficits for fearful faces and, to a lesser extent, for disgusted faces. This finding contradicts recent suggestions that the fearlessness associated with psychopathy is solely a consequence of overt attentional artifacts. Future research should focus on preattentive processing of fear in individuals with callous-unemotional traits, and on the implications of preattentive-processing deficits for treatment and theory development.

  6. Complexity-Measure-Based Sequential Hypothesis Testing for Real-Time Detection of Lethal Cardiac Arrhythmias

    Directory of Open Access Journals (Sweden)

    Chen Szi-Wen

    2007-01-01

    Full Text Available A novel approach that employs a complexity-based sequential hypothesis testing (SHT technique for real-time detection of ventricular fibrillation (VF and ventricular tachycardia (VT is presented. A dataset consisting of a number of VF and VT electrocardiogram (ECG recordings drawn from the MIT-BIH database was adopted for such an analysis. It was split into two smaller datasets for algorithm training and testing, respectively. Each ECG recording was measured in a 10-second interval. For each recording, a number of overlapping windowed ECG data segments were obtained by shifting a 5-second window by a step of 1 second. During the windowing process, the complexity measure (CM value was calculated for each windowed segment and the task of pattern recognition was then sequentially performed by the SHT procedure. A preliminary test conducted using the database produced optimal overall predictive accuracy of . The algorithm was also implemented on a commercial embedded DSP controller, permitting a hardware realization of real-time ventricular arrhythmia detection.

  7. Hypothesis Testing in Unsupervised Domain Adaptation with Applications in Alzheimer's Disease.

    Science.gov (United States)

    Zhou, Hao Henry; Ravi, Sathya N; Ithapu, Vamsi K; Johnson, Sterling C; Wahba, Grace; Singh, Vikas

    2016-01-01

    Consider samples from two different data sources [Formula: see text] and [Formula: see text]. We only observe their transformed versions [Formula: see text] and [Formula: see text], for some known function class h (·) and g (·). Our goal is to perform a statistical test checking if P source = P target while removing the distortions induced by the transformations. This problem is closely related to domain adaptation, and in our case, is motivated by the need to combine clinical and imaging based biomarkers from multiple sites and/or batches - a fairly common impediment in conducting analyses with much larger sample sizes. We address this problem using ideas from hypothesis testing on the transformed measurements, wherein the distortions need to be estimated in tandem with the testing. We derive a simple algorithm and study its convergence and consistency properties in detail, and provide lower-bound strategies based on recent work in continuous optimization. On a dataset of individuals at risk for Alzheimer's disease, our framework is competitive with alternative procedures that are twice as expensive and in some cases operationally infeasible to implement.

  8. Efficient compliance with prescribed bounds on operational parameters by means of hypothesis testing using reactor data

    International Nuclear Information System (INIS)

    Sermer, P.; Olive, C.; Hoppe, F.M.

    2000-01-01

    - A common problem in any reactor operations is to comply with a requirement that certain operational parameters are constrained to lie within some prescribed bounds. The fundamental issue which is to be addressed in any compliance description can be stated as follows: The compliance definition, compliance procedures and allowances for uncertainties in data and accompanying methodologies, should be well defined and justifiable. To this end, a mathematical framework for compliance, in which the computed or measured estimates of process parameters are considered random variables, is described in this paper. This allows a statistical formulation of the definition of compliance with licence or otherwise imposed limits. An important aspect of the proposed methodology is that the derived statistical tests are obtained by a Monte Carlo procedure using actual reactor operational data. The implementation of the methodology requires a routine surveillance of the reactor core in order to perform the underlying statistical tests. The additional work required for surveillance is balanced by the fact that the resulting actions on the reactor operations, implemented in station procedures, make the reactor 'safer' by increasing the operating margins. Furthermore, increased margins are also achieved by efficient solution techniques which may allow an increase in reactor power. A rigorous analysis of a compliance problem using statistical hypothesis testing based on extreme value probability distributions and actual reactor operational data leads to effective solutions in the areas of licensing, nuclear safety, reliability and competitiveness of operating nuclear reactors. (author)

  9. Is intuition really cooperative? Improved tests support the social heuristics hypothesis.

    Science.gov (United States)

    Isler, Ozan; Maule, John; Starmer, Chris

    2018-01-01

    Understanding human cooperation is a major scientific challenge. While cooperation is typically explained with reference to individual preferences, a recent cognitive process view hypothesized that cooperation is regulated by socially acquired heuristics. Evidence for the social heuristics hypothesis rests on experiments showing that time-pressure promotes cooperation, a result that can be interpreted as demonstrating that intuition promotes cooperation. This interpretation, however, is highly contested because of two potential confounds. First, in pivotal studies compliance with time-limits is low and, crucially, evidence shows intuitive cooperation only when noncompliant participants are excluded. The inconsistency of test results has led to the currently unresolved controversy regarding whether or not noncompliant subjects should be included in the analysis. Second, many studies show high levels of social dilemma misunderstanding, leading to speculation that asymmetries in understanding might explain patterns that are otherwise interpreted as intuitive cooperation. We present evidence from an experiment that employs an improved time-pressure protocol with new features designed to induce high levels of compliance and clear tests of understanding. Our study resolves the noncompliance issue, shows that misunderstanding does not confound tests of intuitive cooperation, and provides the first independent experimental evidence for intuitive cooperation in a social dilemma using time-pressure.

  10. Unit testing, model validation, and biological simulation.

    Science.gov (United States)

    Sarma, Gopal P; Jacobs, Travis W; Watts, Mark D; Ghayoomie, S Vahid; Larson, Stephen D; Gerkin, Richard C

    2016-01-01

    The growth of the software industry has gone hand in hand with the development of tools and cultural practices for ensuring the reliability of complex pieces of software. These tools and practices are now acknowledged to be essential to the management of modern software. As computational models and methods have become increasingly common in the biological sciences, it is important to examine how these practices can accelerate biological software development and improve research quality. In this article, we give a focused case study of our experience with the practices of unit testing and test-driven development in OpenWorm, an open-science project aimed at modeling Caenorhabditis elegans. We identify and discuss the challenges of incorporating test-driven development into a heterogeneous, data-driven project, as well as the role of model validation tests, a category of tests unique to software which expresses scientific models.

  11. Feasibility of Combining Common Data Elements Across Studies to Test a Hypothesis.

    Science.gov (United States)

    Corwin, Elizabeth J; Moore, Shirley M; Plotsky, Andrea; Heitkemper, Margaret M; Dorsey, Susan G; Waldrop-Valverde, Drenna; Bailey, Donald E; Docherty, Sharron L; Whitney, Joanne D; Musil, Carol M; Dougherty, Cynthia M; McCloskey, Donna J; Austin, Joan K; Grady, Patricia A

    2017-05-01

    The purpose of this article is to describe the outcomes of a collaborative initiative to share data across five schools of nursing in order to evaluate the feasibility of collecting common data elements (CDEs) and developing a common data repository to test hypotheses of interest to nursing scientists. This initiative extended work already completed by the National Institute of Nursing Research CDE Working Group that successfully identified CDEs related to symptoms and self-management, with the goal of supporting more complex, reproducible, and patient-focused research. Two exemplars describing the group's efforts are presented. The first highlights a pilot study wherein data sets from various studies by the represented schools were collected retrospectively, and merging of the CDEs was attempted. The second exemplar describes the methods and results of an initiative at one school that utilized a prospective design for the collection and merging of CDEs. Methods for identifying a common symptom to be studied across schools and for collecting the data dictionaries for the related data elements are presented for the first exemplar. The processes for defining and comparing the concepts and acceptable values, and for evaluating the potential to combine and compare the data elements are also described. Presented next are the steps undertaken in the second exemplar to prospectively identify CDEs and establish the data dictionaries. Methods for common measurement and analysis strategies are included. Findings from the first exemplar indicated that without plans in place a priori to ensure the ability to combine and compare data from disparate sources, doing so retrospectively may not be possible, and as a result hypothesis testing across studies may be prohibited. Findings from the second exemplar, however, indicated that a plan developed prospectively to combine and compare data sets is feasible and conducive to merged hypothesis testing. Although challenges exist in

  12. Testing a growth efficiency hypothesis with continental-scale phenological variations of common and cloned plants.

    Science.gov (United States)

    Liang, Liang; Schwartz, Mark D

    2014-10-01

    Variation in the timing of plant phenology caused by phenotypic plasticity is a sensitive measure of how organisms respond to weather and climate variability. Although continental-scale gradients in climate and consequential patterns in plant phenology are well recognized, the contribution of underlying genotypic difference to the geography of phenology is less well understood. We hypothesize that different temperate plant genotypes require varying amount of heat energy for resuming annual growth and reproduction as a result of adaptation and other ecological and evolutionary processes along climatic gradients. In particular, at least for some species, the growing degree days (GDD) needed to trigger the same spring phenology events (e.g., budburst and flower bloom) may be less for individuals originated from colder climates than those from warmer climates. This variable intrinsic heat energy requirement in plants can be characterized by the term growth efficiency and is quantitatively reflected in the timing of phenophases-earlier timing indicates higher efficiency (i.e., less heat energy needed to trigger phenophase transitions) and vice versa compared to a standard reference (i.e., either a uniform climate or a uniform genotype). In this study, we tested our hypothesis by comparing variations of budburst and bloom timing of two widely documented plants from the USA National Phenology Network (i.e., red maple-Acer rubrum and forsythia-Forsythia spp.) with cloned indicator plants (lilac-Syringa x chinensis 'Red Rothomagensis') at multiple eastern US sites. Our results indicate that across the accumulated temperature gradient, the two non-clonal plants showed significantly more gradual changes than the cloned plants, manifested by earlier phenology in colder climates and later phenology in warmer climates relative to the baseline clone phenological response. This finding provides initial evidence supporting the growth efficiency hypothesis, and suggests more work is

  13. Childhood IQ and adult mental disorders: a test of the cognitive reserve hypothesis.

    Science.gov (United States)

    Koenen, Karestan C; Moffitt, Terrie E; Roberts, Andrea L; Martin, Laurie T; Kubzansky, Laura; Harrington, HonaLee; Poulton, Richie; Caspi, Avshalom

    2009-01-01

    Cognitive reserve has been proposed as important in the etiology of neuropsychiatric disorders. However, tests of the association between premorbid IQ and adult mental disorders other than schizophrenia have been limited and inconclusive. The authors tested the hypothesis that low childhood IQ is associated with increased risk and severity of adult mental disorders. Participants were members of a representative 1972-1973 birth cohort of 1,037 males and females in Dunedin, New Zealand, who were followed up to age 32 with 96% retention. WISC-R IQ was assessed at ages 7, 9, and 11. Research diagnoses of DSM mental disorders were made at ages 18, 21, 26, and 32. Lower childhood IQ was associated with increased risk of developing schizophrenia spectrum disorder, adult depression, and adult anxiety. Lower childhood IQ was also associated with greater comorbidity and with persistence of depression; the association with persistence of generalized anxiety disorder was nearly significant. Higher childhood IQ predicted increased risk of adult mania. Lower cognitive reserve, as reflected by childhood IQ, is an antecedent of several common psychiatric disorders and also predicts persistence and comorbidity. Thus, many patients who seek mental health treatment may have lower cognitive ability; this should be considered in prevention and treatment planning.

  14. Globigerinoides ruber morphotypes in the Gulf of Mexico: a test of null hypothesis.

    Science.gov (United States)

    Thirumalai, Kaustubh; Richey, Julie N; Quinn, Terrence M; Poore, Richard Z

    2014-08-11

    Planktic foraminifer Globigerinoides ruber (G. ruber), due to its abundance and ubiquity in the tropical/subtropical mixed layer, has been the workhorse of paleoceanographic studies investigating past sea-surface conditions on a range of timescales. Recent geochemical work on the two principal white G. ruber (W) morphotypes, sensu stricto (ss) and sensu lato (sl), has hypothesized differences in seasonal preferences or calcification depths, implying that reconstructions using a non-selective mixture of morphotypes could potentially be biased. Here, we test these hypotheses by performing stable isotope and abundance measurements on the two morphotypes in sediment trap, core-top, and downcore samples from the northern Gulf of Mexico. As a test of null hypothesis, we perform the same analyses on couplets of G. ruber (W) specimens with attributes intermediate to the holotypic ss and sl morphologies. We find no systematic or significant offsets in coeval ss-sl δ(18)O, and δ(13)C. These offsets are no larger than those in the intermediate pairs. Coupling our results with foraminiferal statistical model INFAUNAL, we find that contrary to previous work elsewhere, there is no evidence for discrepancies in ss-sl calcifying depth habitat or seasonality in the Gulf of Mexico.

  15. Testing the relativistic Doppler boost hypothesis for supermassive black hole binary candidates

    Science.gov (United States)

    Charisi, Maria; Haiman, Zoltán; Schiminovich, David; D'Orazio, Daniel J.

    2018-02-01

    Supermassive black hole binaries (SMBHBs) should be common in galactic nuclei as a result of frequent galaxy mergers. Recently, a large sample of sub-parsec SMBHB candidates was identified as bright periodically variable quasars in optical surveys. If the observed periodicity corresponds to the redshifted binary orbital period, the inferred orbital velocities are relativistic (v/c ≈ 0.1). The optical and UV luminosities are expected to arise from gas bound to the individual BHs, and would be modulated by the relativistic Doppler effect. The optical and UV light curves should vary in tandem with relative amplitudes which depend on the respective spectral slopes. We constructed a control sample of 42 quasars with aperiodic variability, to test whether this Doppler colour signature can be distinguished from intrinsic chromatic variability. We found that the Doppler signature can arise by chance in ˜20% (˜37%) of quasars in the nUV (fUV) band. These probabilities reflect the limited quality of the control sample and represent upper limits on how frequently quasars mimic the Doppler brightness+colour variations. We performed separate tests on the periodic quasar candidates, and found that for the majority, the Doppler boost hypothesis requires an unusually steep UV spectrum or an unexpectedly large BH mass and orbital velocity. We conclude that at most ˜1/3rd of these periodic candidates can harbor Doppler-modulated SMBHBs.

  16. Testing the enemy release hypothesis in a native insect species with an expanding range

    Directory of Open Access Journals (Sweden)

    Julia J. Mlynarek

    2015-11-01

    Full Text Available The enemy release hypothesis (ERH predicts that the spread of (invasive species will be facilitated by release from their enemies as they occupy new areas. However, the ERH is rarely tested on native (non-invasive, long established species with expanding or shifting ranges. I tested the ERH for a native damselfly (Enallagma clausum whose range has recently expanded in western Canada, with respect to its water mite and gregarine parasites. Parasitism levels (prevalence and intensity were also compared between E. clausum and a closely related species, Enallagma boreale, which has long been established in the study region and whose range is not shifting. A total of 1,150 damselflies were collected at three ‘old’ sites for E. clausum in Saskatchewan, and three ‘new’ sites in Alberta. A little more than a quarter of the damselflies collected were parasitized with, on average, 18 water mite individuals, and 20% were parasitized by, on average, 10 gregarine individuals. I assessed whether the differences between levels of infection (prevalence and intensity were due to site type or host species. The ERH was not supported: Enallagma clausum has higher or the same levels of parasitism in new sites than old sites. However, E. boreale seems to be benefitting from the recent range expansion of a native, closely related species through ecological release from its parasites because the parasites may be choosing to infest the novel, potentially naïve, host instead of the well-established host.

  17. Polygyny among the Tsimane of Bolivia: an improved method for testing the polygyny-fertility hypothesis.

    Science.gov (United States)

    Winking, Jeffrey; Stieglitz, Jonathan; Kurten, Jenna; Kaplan, Hillard; Gurven, Michael

    2013-04-07

    The polygyny-fertility hypothesis states that polygyny is associated with reduced fertility for women and is supported by a large body of literature. This finding is important, because theoretical models of polygyny often differentiate systems based on the degree to which women are forced or willingly choose to enter polygynous marriages. The fact that polygyny tends to be associated with reduced fertility has been presented as evidence that polygyny is often less favourable for women, and that women must, therefore, be pressured into accepting such arrangements. Previous studies, however, have been hampered by the non-random assignment of women into monogamous and polygynous unions (i.e. self-selection), as differences between these groups of women might explain some of the effects. Furthermore, the vast majority of such studies focus on sub-Saharan populations. We address these problems in our analysis of women's fertility in polygynous marriages among the Tsimane of Bolivia. We offer a more robust method for assessing the impact of polygynous marriage on reproductive outcomes by testing for intra-individual fertility effects among first wives as they transition from monogamous to polygynous marriage. We report a significant link between polygyny and reduced fertility when including all cases of polygyny; however, this association disappears when testing only for intra-individual effects.

  18. Colour vision in ADHD: part 1--testing the retinal dopaminergic hypothesis.

    Science.gov (United States)

    Kim, Soyeon; Al-Haj, Mohamed; Chen, Samantha; Fuller, Stuart; Jain, Umesh; Carrasco, Marisa; Tannock, Rosemary

    2014-10-24

    To test the retinal dopaminergic hypothesis, which posits deficient blue color perception in ADHD, resulting from hypofunctioning CNS and retinal dopamine, to which blue cones are exquisitely sensitive. Also, purported sex differences in red color perception were explored. 30 young adults diagnosed with ADHD and 30 healthy young adults, matched on age and gender, performed a psychophysical task to measure blue and red color saturation and contrast discrimination ability. Visual function measures, such as the Visual Activities Questionnaire (VAQ) and Farnsworth-Munsell 100 hue test (FMT), were also administered. Females with ADHD were less accurate in discriminating blue and red color saturation relative to controls but did not differ in contrast sensitivity. Female control participants were better at discriminating red saturation than males, but no sex difference was present within the ADHD group. Poorer discrimination of red as well as blue color saturation in the female ADHD group may be partly attributable to a hypo-dopaminergic state in the retina, given that color perception (blue-yellow and red-green) is based on input from S-cones (short wavelength cone system) early in the visual pathway. The origin of female superiority in red perception may be rooted in sex-specific functional specialization in hunter-gather societies. The absence of this sexual dimorphism for red colour perception in ADHD females warrants further investigation.

  19. Polygyny among the Tsimane of Bolivia: an improved method for testing the polygyny–fertility hypothesis

    Science.gov (United States)

    Winking, Jeffrey; Stieglitz, Jonathan; Kurten, Jenna; Kaplan, Hillard; Gurven, Michael

    2013-01-01

    The polygyny–fertility hypothesis states that polygyny is associated with reduced fertility for women and is supported by a large body of literature. This finding is important, because theoretical models of polygyny often differentiate systems based on the degree to which women are forced or willingly choose to enter polygynous marriages. The fact that polygyny tends to be associated with reduced fertility has been presented as evidence that polygyny is often less favourable for women, and that women must, therefore, be pressured into accepting such arrangements. Previous studies, however, have been hampered by the non-random assignment of women into monogamous and polygynous unions (i.e. self-selection), as differences between these groups of women might explain some of the effects. Furthermore, the vast majority of such studies focus on sub-Saharan populations. We address these problems in our analysis of women's fertility in polygynous marriages among the Tsimane of Bolivia. We offer a more robust method for assessing the impact of polygynous marriage on reproductive outcomes by testing for intra-individual fertility effects among first wives as they transition from monogamous to polygynous marriage. We report a significant link between polygyny and reduced fertility when including all cases of polygyny; however, this association disappears when testing only for intra-individual effects. PMID:23407840

  20. Depression as sickness behavior? A test of the host defense hypothesis in a high pathogen population.

    Science.gov (United States)

    Stieglitz, Jonathan; Trumble, Benjamin C; Thompson, Melissa Emery; Blackwell, Aaron D; Kaplan, Hillard; Gurven, Michael

    2015-10-01

    Sadness is an emotion universally recognized across cultures, suggesting it plays an important functional role in regulating human behavior. Numerous adaptive explanations of persistent sadness interfering with daily functioning (hereafter "depression") have been proposed, but most do not explain frequent bidirectional associations between depression and greater immune activation. Here we test several predictions of the host defense hypothesis, which posits that depression is part of a broader coordinated evolved response to infection or tissue injury (i.e. "sickness behavior") that promotes energy conservation and reallocation to facilitate immune activation. In a high pathogen population of lean and relatively egalitarian Bolivian forager-horticulturalists, we test whether depression and its symptoms are associated with greater baseline concentration of immune biomarkers reliably associated with depression in Western populations (i.e. tumor necrosis factor alpha [TNF-α], interleukin-1 beta [IL-1β], interleukin-6 [IL-6], and C-reactive protein [CRP]). We also test whether greater pro-inflammatory cytokine responses to ex vivo antigen stimulation are associated with depression and its symptoms, which is expected if depression facilitates immune activation. These predictions are largely supported in a sample of older adult Tsimane (mean±SD age=53.2±11.0, range=34-85, n=649) after adjusting for potential confounders. Emotional, cognitive and somatic symptoms of depression are each associated with greater immune activation, both at baseline and in response to ex vivo stimulation. The association between depression and greater immune activation is therefore not unique to Western populations. While our findings are not predicted by other adaptive hypotheses of depression, they are not incompatible with those hypotheses and future research is necessary to isolate and test competing predictions. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. On the Flexibility of Social Source Memory: A Test of the Emotional Incongruity Hypothesis

    Science.gov (United States)

    Bell, Raoul; Buchner, Axel; Kroneisen, Meike; Giang, Trang

    2012-01-01

    A popular hypothesis in evolutionary psychology posits that reciprocal altruism is supported by a cognitive module that helps cooperative individuals to detect and remember cheaters. Consistent with this hypothesis, a source memory advantage for faces of cheaters (better memory for the cheating context in which these faces were encountered) was…

  2. Testing the hypothesis of the natural suicide rates: Further evidence from OECD data

    DEFF Research Database (Denmark)

    Andres, Antonio Rodriguez; Halicioglu, Ferda

    2011-01-01

    This paper provides further evidence on the hypothesis of the natural rate of suicide using the time series data for 15 OECD countries over the period 1970–2004. This hypothesis suggests that the suicide rate of a society could never be zero even if both the economic and the social conditions wer...

  3. Cohesion, Adaptability and Communication: A Test of an Olson Circumplex Model Hypothesis.

    Science.gov (United States)

    Anderson, Stephen A.

    1986-01-01

    Examined the hypothesis that families balanced on the dimensions of cohesion and adaptability would evidence more positive communication skills. In general, the hypothesis was supported. However, the results were more consistent for the cohesion dimension than for adaptability. Also, sex differences were found. (Author/BL)

  4. Testing the cultural group selection hypothesis in Northern Ghana and Oaxaca.

    Science.gov (United States)

    Acedo-Carmona, Cristina; Gomila, Antoni

    2016-01-01

    We examine the cultural group selection (CGS) hypothesis in light of our fieldwork in Northern Ghana and Oaxaca, highly multi-ethnic regions. Our evidence fails to corroborate two central predictions of the hypothesis: that the cultural group is the unit of evolution, and that cultural homogenization is to be expected as the outcome of a selective process.

  5. Bayesian hypothesis testing: Editorial to the Special Issue on Bayesian data analysis.

    Science.gov (United States)

    Hoijtink, Herbert; Chow, Sy-Miin

    2017-06-01

    In the past 20 years, there has been a steadily increasing attention and demand for Bayesian data analysis across multiple scientific disciplines, including psychology. Bayesian methods and the related Markov chain Monte Carlo sampling techniques offered renewed ways of handling old and challenging new problems that may be difficult or impossible to handle using classical approaches. Yet, such opportunities and potential improvements have not been sufficiently explored and investigated. This is 1 of 2 special issues in Psychological Methods dedicated to the topic of Bayesian data analysis, with an emphasis on Bayesian hypothesis testing, model comparison, and general guidelines for applications in psychology. In this editorial, we provide an overview of the use of Bayesian methods in psychological research and a brief history of the Bayes factor and the posterior predictive p value. Translational abstracts that summarize the articles in this issue in very clear and understandable terms are included in the Appendix. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  6. Oral sex, semen displacement, and sexual arousal: testing the ejaculate adjustment hypothesis.

    Science.gov (United States)

    Pham, Michael N; Shackelford, Todd K; Welling, Lisa L M; Ehrke, Alyse D; Sela, Yael; Goetz, Aaron T

    2013-12-20

    Male Indian Flying Foxes (Pteropus giganteus) that spend more time performing oral sex on a female also spend more time copulating with her. In humans, men who spend more time copulating with their regular partner also perform more "semen-displacing" copulatory behaviors (e.g., deeper, more vigorous penile thrusting). We investigated whether men who spend more time performing oral sex on their regular partner also spend more time copulating with her and perform more semen-displacing copulatory behaviors. We proposed and tested the ejaculate adjustment hypothesis for men's copulatory behaviors: Men adjust their copulatory behaviors to increase their sexual arousal and consequent ejaculate quality, thereby increasing their chances of success in sperm competition. Two hundred and thirty-three men in a committed, heterosexual relationship responded to questions about their copulatory behavior and sexual arousal during their most recent sexual encounter with their long-term partner. The results indicated that men who spend more time performing oral sex on their partner also spend more time copulating with her, perform more semen-displacing copulatory behaviors, and report greater sexual arousal. We discuss limitations to the current research and highlight the heuristic value of sperm competition theory for understanding human sexual behaviors.

  7. Role for circadian clock genes in seasonal timing: testing the Bünning hypothesis.

    Directory of Open Access Journals (Sweden)

    Mirko Pegoraro

    2014-09-01

    Full Text Available A major question in chronobiology focuses around the "Bünning hypothesis" which implicates the circadian clock in photoperiodic (day-length measurement and is supported in some systems (e.g. plants but disputed in others. Here, we used the seasonally-regulated thermotolerance of Drosophila melanogaster to test the role of various clock genes in day-length measurement. In Drosophila, freezing temperatures induce reversible chill coma, a narcosis-like state. We have corroborated previous observations that wild-type flies developing under short photoperiods (winter-like exhibit significantly shorter chill-coma recovery times (CCRt than flies that were raised under long (summer-like photoperiods. Here, we show that arrhythmic mutant strains, per01, tim01 and ClkJrk, as well as variants that speed up or slow down the circadian period, disrupt the photoperiodic component of CCRt. Our results support an underlying circadian function mediating seasonal daylength measurement and indicate that clock genes are tightly involved in photo- and thermo-periodic measurements.

  8. Temporal variability and cooperative breeding: testing the bet-hedging hypothesis in the acorn woodpecker.

    Science.gov (United States)

    Koenig, Walter D; Walters, Eric L

    2015-10-07

    Cooperative breeding is generally considered an adaptation to ecological constraints on dispersal and independent breeding, usually due to limited breeding opportunities. Although benefits of cooperative breeding are typically thought of in terms of increased mean reproductive success, it has recently been proposed that this phenomenon may be a bet-hedging strategy that reduces variance in reproductive success (fecundity variance) in populations living in highly variable environments. We tested this hypothesis using long-term data on the polygynandrous acorn woodpecker (Melanerpes formicivorus). In general, fecundity variance decreased with increasing sociality, at least when controlling for annual variation in ecological conditions. Nonetheless, decreased fecundity variance was insufficient to compensate for reduced per capita reproductive success of larger, more social groups, which typically suffered lower estimated mean fitness. We did, however, find evidence that sociality in the form of larger group size resulted in increased fitness in years following a small acorn crop due to reduced fecundity variance. Bet-hedging, although not the factor driving sociality in general, may play a role in driving acorn woodpecker group living when acorns are scarce and ecological conditions are poor. © 2015 The Author(s).

  9. FADTTSter: accelerating hypothesis testing with functional analysis of diffusion tensor tract statistics

    Science.gov (United States)

    Noel, Jean; Prieto, Juan C.; Styner, Martin

    2017-03-01

    Functional Analysis of Diffusion Tensor Tract Statistics (FADTTS) is a toolbox for analysis of white matter (WM) fiber tracts. It allows associating diffusion properties along major WM bundles with a set of covariates of interest, such as age, diagnostic status and gender, and the structure of the variability of these WM tract properties. However, to use this toolbox, a user must have an intermediate knowledge in scripting languages (MATLAB). FADTTSter was created to overcome this issue and make the statistical analysis accessible to any non-technical researcher. FADTTSter is actively being used by researchers at the University of North Carolina. FADTTSter guides non-technical users through a series of steps including quality control of subjects and fibers in order to setup the necessary parameters to run FADTTS. Additionally, FADTTSter implements interactive charts for FADTTS' outputs. This interactive chart enhances the researcher experience and facilitates the analysis of the results. FADTTSter's motivation is to improve usability and provide a new analysis tool to the community that complements FADTTS. Ultimately, by enabling FADTTS to a broader audience, FADTTSter seeks to accelerate hypothesis testing in neuroimaging studies involving heterogeneous clinical data and diffusion tensor imaging. This work is submitted to the Biomedical Applications in Molecular, Structural, and Functional Imaging conference. The source code of this application is available in NITRC.

  10. Testing the Prey-Trap Hypothesis at Two Wildlife Conservancies in Kenya.

    Directory of Open Access Journals (Sweden)

    Marc Dupuis-Desormeaux

    Full Text Available Protecting an endangered and highly poached species can conflict with providing an open and ecologically connected landscape for coexisting species. In Kenya, about half of the black rhino (Diceros bicornis live in electrically fenced private conservancies. Purpose-built fence-gaps permit some landscape connectivity for elephant while restricting rhino from escaping. We monitored the usage patterns at these gaps by motion-triggered cameras and found high traffic volumes and predictable patterns of prey movement. The prey-trap hypothesis (PTH proposes that predators exploit this predictable prey movement. We tested the PTH at two semi-porous reserves using two different methods: a spatial analysis and a temporal analysis. Using spatial analysis, we mapped the location of predation events with GPS and looked for concentration of kill sites near the gaps as well as conducting clustering and hot spot analysis to determine areas of statistically significant predation clustering. Using temporal analysis, we examined the time lapse between the passage of prey and predator and searched for evidence of active prey seeking and/or predator avoidance. We found no support for the PTH and conclude that the design of the fence-gaps is well suited to promoting connectivity in these types of conservancies.

  11. Testing the universality of biology: a review

    International Nuclear Information System (INIS)

    Chela-Flores, J.

    2007-08-01

    We discuss whether it is possible to test the universality of biology, a quest that is of paramount relevance for one of its most recent branches, namely astrobiology. We review this topic in terms of the relative roles played on the Earth biota by contingency and evolutionary convergence. Following the seminal contribution of Darwin, it is reasonable to assume that all forms of life known to us so far are not only terrestrial, but are descendants of a common ancestor that evolved on this planet at the end of a process of chemical evolution. We also raise the related question of whether the molecular events that were precursors to the origin of life on Earth are bound to occur elsewhere in the universe, wherever the environmental conditions are similar to the terrestrial ones. We refer to 'cosmic convergence' as the possible occurrence elsewhere in the universe of Earth-like environmental conditions. We argue that cosmic convergence is already suggested by observational data. The set of hypotheses for addressing the question of the universality of biology can be tested by future experiments that are feasible with current technology. We focus on landing on Europa and the broader implications of selecting the specific example of the right landing location. We had discussed earlier the corresponding miniaturized equipment that is already in existence. The significance of these crucial points needs to be put into a wider scientific perspective, which is one of the main objectives of this review. (author)

  12. Testing the universality of biology: a review

    International Nuclear Information System (INIS)

    Chela-Flores, J.

    2007-05-01

    We discuss whether it is possible to test the universality of biology, a quest that is of paramount relevance for one of its most recent branches, namely astrobiology. We review this topic in terms of the relative roles played on the Earth biota by contingency and evolutionary convergence. Following the seminal contribution of Darwin, it is reasonable to assume that all forms of life known to us so far are not only terrestrial, but are descendants of a common ancestor that evolved on this planet at the end of a process of chemical evolution. We also raise the related question of whether the molecular events that were precursors to the origin of life on Earth are bound to occur elsewhere in the universe, wherever the environmental conditions are similar to the terrestrial ones. We refer to 'cosmic convergence' as the possible occurrence elsewhere in the universe of Earth-like environmental conditions. We argue that cosmic convergence is already suggested by observational data. The set of hypotheses for addressing the question of the universality of biology can be tested by future experiments that are feasible with current technology. We focus on landing on Europe and the broader implications of selecting the specific example of the right landing location. We had discussed earlier the corresponding miniaturized equipment that is already in existence. The significance of these crucial points needs to be put into a wider scientific perspective, which is one of the main objectives of this review. (author)

  13. Stimulation of interferons and endorphins/enkephalins by electro-aerosol inhalation? An experimental approach for testing an expanded hypothesis

    Science.gov (United States)

    Wehner, A. P.

    1984-03-01

    The biological effects of endorphins/enkephalins and of interferons closely resemble those attributed to air ions and electro-aerosols. Air ions/electro-aerosols have been reported to affect brain functions and feelings of “well-being”; to have sedative and analgesic effects; to be therapeutically effective in certain viral (e.g., upper respiratory) infections; and to have tumor-attenuating effects. It is, therefore, conceivable that endorphins/enkephalins and interferons might be the mediators of these air ion/electro-aerosol effects. An experimental approach for testing this hypothesis is described. It calls for mice to be challenged with a suitable agent and to be exposed under appropriate conditions to a negatively charged aerosol of physiological saline 6 hours/day for up to 3 weeks; for the serial sacrifice of subgroups of these mice; for collecting blood and brains of the sacrificed animals; for the bioassay of the sera for interferon; and for radioimmunoassays of brains for endorphins/enkephalins. Special considerations, necessitated by the nature of the experiment, are discussed.

  14. On the geometric modeling approach to empirical null distribution estimation for empirical Bayes modeling of multiple hypothesis testing.

    Science.gov (United States)

    Wu, Baolin

    2013-04-01

    We study the geometric modeling approach to estimating the null distribution for the empirical Bayes modeling of multiple hypothesis testing. The commonly used method is a nonparametric approach based on the Poisson regression, which however could be unduly affected by the dependence among test statistics and perform very poorly under strong dependence. In this paper, we explore a finite mixture model based geometric modeling approach to empirical null distribution estimation and multiple hypothesis testing. Through simulations and applications to two public microarray data, we will illustrate its competitive performance. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Testing the stress gradient hypothesis in herbivore communities: facilitation peaks at intermediate nutrient levels

    NARCIS (Netherlands)

    Bakker, E.S.; Dobrescu, I.; Straile, D.; Holmgren, M.

    2013-01-01

    The role of positive interactions in structuring plant and animal communities is increasingly recognized, but the generality of current theoretical models has remained practically unexplored in animal communities. The stress gradient hypothesis predicts a linear increase in the intensity of

  16. Possible Solution to Publication Bias Through Bayesian Statistics, Including Proper Null Hypothesis Testing

    NARCIS (Netherlands)

    Konijn, Elly A.; van de Schoot, Rens; Winter, Sonja D.; Ferguson, Christopher J.

    2015-01-01

    The present paper argues that an important cause of publication bias resides in traditional frequentist statistics forcing binary decisions. An alternative approach through Bayesian statistics provides various degrees of support for any hypothesis allowing balanced decisions and proper null

  17. Testing the niche variation hypothesis with a measure of body condition

    Science.gov (United States)

    Individual variation and fitness are cornerstones of evolution by natural selection. The niche variation hypothesis (NVH) posits that when interspecific competition is relaxed, intraspecific competition should drive niche expansion by selection favoring use of novel resources. Po...

  18. Testing the sexual imagination hypothesis for gender differences in response to infidelity

    OpenAIRE

    Kato, Tsukasa

    2014-01-01

    Background Evolutionary psychologists hypothesized that men are more upset by sexual infidelity than women are, whereas women are more upset by emotional infidelity than men are. On the other hand, the sexual imagination hypothesis states that gender differences in infidelity responses are derived from explicit men’s sexual imagery. Based on the latter hypothesis, we hypothesized that although men would report being more distressed by sexual infidelity than women who were not in a committed r...

  19. Prospective Tests on Biological Models of Acupuncture

    Directory of Open Access Journals (Sweden)

    Charles Shang

    2009-01-01

    Full Text Available The biological effects of acupuncture include the regulation of a variety of neurohumoral factors and growth control factors. In science, models or hypotheses with confirmed predictions are considered more convincing than models solely based on retrospective explanations. Literature review showed that two biological models of acupuncture have been prospectively tested with independently confirmed predictions: The neurophysiology model on the long-term effects of acupuncture emphasizes the trophic and anti-inflammatory effects of acupuncture. Its prediction on the peripheral effect of endorphin in acupuncture has been confirmed. The growth control model encompasses the neurophysiology model and suggests that a macroscopic growth control system originates from a network of organizers in embryogenesis. The activity of the growth control system is important in the formation, maintenance and regulation of all the physiological systems. Several phenomena of acupuncture such as the distribution of auricular acupuncture points, the long-term effects of acupuncture and the effect of multimodal non-specific stimulation at acupuncture points are consistent with the growth control model. The following predictions of the growth control model have been independently confirmed by research results in both acupuncture and conventional biomedical sciences: (i Acupuncture has extensive growth control effects. (ii Singular point and separatrix exist in morphogenesis. (iii Organizers have high electric conductance, high current density and high density of gap junctions. (iv A high density of gap junctions is distributed as separatrices or boundaries at body surface after early embryogenesis. (v Many acupuncture points are located at transition points or boundaries between different body domains or muscles, coinciding with the connective tissue planes. (vi Some morphogens and organizers continue to function after embryogenesis. Current acupuncture research suggests a

  20. The childhood maltreatment influences on breast cancer patients: A second wave hit model hypothesis for distinct biological and behavioral response.

    Science.gov (United States)

    Bandinelli, Lucas Poitevin; Levandowski, Mateus Luz; Grassi-Oliveira, Rodrigo

    2017-10-01

    Stress and cancer are two complex situations involving different biological and psychological mechanisms. Their relationship have long been studied, and there is evidence of the impact stress has on both, development and disease progression. Furthermore, early stress has been studied as an important factor associated to this relationship, since its impacts on the immune, endocrine and cognitive development throughout life is already known. Therefore, understanding early stress as a first wave of stress in life is necessary in order to explore a possible second wave hit model. From this perspective, we believe that breast cancer can be understood as a second wave of stress during development and that, in addition to the first wave, can cause important impacts on the response to cancer treatment, such as increased chances of disease progression and distinct behavioral responses. In this article we propose a second wave hit hypothesis applied to breast cancer and its implications on the immune, endocrine and cognitive systems, through mechanisms that involve the HPA axis and subsequent activations of stress responses. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Community-Driven Hypothesis Testing: A Solution for the Tragedy of the Anticommons.

    Science.gov (United States)

    Palma-Oliveira, José Manuel; Trump, Benjamin D; Wood, Matthew D; Linkov, Igor

    2018-03-01

    Shared ownership of property and resources is a longstanding challenge throughout history that has been amplifying with the increasing development of industrial and postindustrial societies. Where governments, project planners, and commercial developers seek to develop new infrastructure, industrial projects, and various other land-and resource-intensive tasks, veto power shared by various local stakeholders can complicate or halt progress. Risk communication has been used as an attempt to address stakeholder concerns in these contexts, but has demonstrated shortcomings. These coordination failures between project planners and stakeholders can be described as a specific kind of social dilemma that we describe as the "tragedy of the anticommons." To overcome such dilemmas, we demonstrate how a two-step process can directly address public mistrust of project planners and public perceptions of limited decision-making authority. This approach is examined via two separate empirical field experiments in Portugal and Tunisia, where public resistance and anticommons problems threatened to derail emerging industrial projects. In both applications, an intervention is undertaken to address initial public resistance to such projects, where specific public stakeholders and project sponsors collectively engaged in a hypothesis-testing process to identify and assess human and environmental health risks associated with proposed industrial facilities. These field experiments indicate that a rigorous attempt to address public mistrust and perceptions of power imbalances and change the pay-off structure of the given dilemma may help overcome such anticommons problems in specific cases, and may potentially generate enthusiasm and support for such projects by local publics moving forward. © 2017 Society for Risk Analysis.

  2. The hard parts of the Cambrian Explosion: a palaeobiological approach to testing the 'biomineralization toolkit' hypothesis

    Science.gov (United States)

    Murdock, Duncan

    2017-04-01

    The Cambrian Explosion was the most dramatic event in the history of animal life on Earth, yet the processes underlying it are poorly understood not least the role of biomineralization in driving this fundamental evolutionary episode. One explanation for this event, based on observations on the developmental and molecular biology of modern organisms, is that all animals inherited a common 'toolkit' of genes, independently co-opted to similar tasks, including building skeletons. This initially imprecise 'toolkit' was subsequently honed by the acquisition of more and more complex gene regulatory networks. This predicts that animal skeletons, and by inference their organic frameworks, should exhibit a higher degree of morphological plasticity at their origin than later in their evolutionary history - a prediction that is virtually untested. Here I set out a new approach to testing this prediction, by quantifying the phenotypic variation displayed in fossil remains of some of the earliest animal skeletons, over multiple scales from microscopic variations in their component biominerals to how skeletons themselves are put together. This approach will provide direct evidence to test the importance of the genetic basis of the skeleton in the origin of the animals, making a significant contribution to our understanding of this crucial event in the history of life on Earth, including the evolution of our own ancestors.

  3. The Bayesian New Statistics: Hypothesis testing, estimation, meta-analysis, and power analysis from a Bayesian perspective.

    Science.gov (United States)

    Kruschke, John K; Liddell, Torrin M

    2018-02-01

    In the practice of data analysis, there is a conceptual distinction between hypothesis testing, on the one hand, and estimation with quantified uncertainty on the other. Among frequentists in psychology, a shift of emphasis from hypothesis testing to estimation has been dubbed "the New Statistics" (Cumming 2014). A second conceptual distinction is between frequentist methods and Bayesian methods. Our main goal in this article is to explain how Bayesian methods achieve the goals of the New Statistics better than frequentist methods. The article reviews frequentist and Bayesian approaches to hypothesis testing and to estimation with confidence or credible intervals. The article also describes Bayesian approaches to meta-analysis, randomized controlled trials, and power analysis.

  4. Testing the Münch hypothesis of long distance phloem transport in plants

    Science.gov (United States)

    Knoblauch, Michael; Knoblauch, Jan; Mullendore, Daniel L; Savage, Jessica A; Babst, Benjamin A; Beecher, Sierra D; Dodgen, Adam C; Jensen, Kaare H; Holbrook, N Michele

    2016-01-01

    Long distance transport in plants occurs in sieve tubes of the phloem. The pressure flow hypothesis introduced by Ernst Münch in 1930 describes a mechanism of osmotically generated pressure differentials that are supposed to drive the movement of sugars and other solutes in the phloem, but this hypothesis has long faced major challenges. The key issue is whether the conductance of sieve tubes, including sieve plate pores, is sufficient to allow pressure flow. We show that with increasing distance between source and sink, sieve tube conductivity and turgor increases dramatically in Ipomoea nil. Our results provide strong support for the Münch hypothesis, while providing new tools for the investigation of one of the least understood plant tissues. DOI: http://dx.doi.org/10.7554/eLife.15341.001 PMID:27253062

  5. Testing the Münch hypothesis of long distance phloem transport in plants

    DEFF Research Database (Denmark)

    Knoblauch, Michael; Knoblauch, Jan; Mullendore, Daniel L.

    2016-01-01

    Long distance transport in plants occurs in sieve tubes of the phloem. The pressure flow hypothesis introduced by Ernst Münch in 1930 describes a mechanism of osmotically generated pressure differentials that are supposed to drive the movement of sugars and other solutes in the phloem......, but this hypothesis has long faced major challenges. The key issue is whether the conductance of sieve tubes, including sieve plate pores, is sufficient to allow pressure flow. We show that with increasing distance between source and sink, sieve tube conductivity and turgor increases dramatically in Ipomoea nil. Our...

  6. A hydrometric and geochemical approach to test the transmissivity feedback hypothesis during snowmelt

    Science.gov (United States)

    Kendall, K.A.; Shanley, J.B.; McDonnell, Jeffery J.

    1999-01-01

    To test the transmissivity feedback hypothesis of runoff generation, surface and subsurface waters were monitored and sampled during the 1996 snowmelt at various topographic positions in a 41 ha forested headwater catchment at Sleepers River, Vermont. Two conditions that promote transmissivity feedback existed in the catchment during the melt period. First, saturated hydraulic conductivity increased toward land surface, from a geometric mean of 3.6 mm h-1 in glacial till to 25.6 mm h-1 in deep soil to 54.0 mm h-1 in shallow soil. Second, groundwater levels rose to within 0.3 m of land surface at all riparian sites and most hillslope sites at peak melt. The importance of transmissivity feedback to streamflow generation was tested at the catchment scale by examination of physical and chemical patterns of groundwater in near-stream (discharge) and hillslope (recharge/lateral flow) zones, and within a geomorphic hollow (convergent flow). The presence of transmissivity feedback was supported by the abrupt increase in streamflow as the water table rose into the surficial, transmissive zone; a flattening of the groundwater level vs. streamflow curve occurred at most sites. This relation had a clockwise hysteresis (higher groundwater level for given discharge on rising limb than at same discharge on falling limb) at riparian sites, suggesting that the riparian zone was the dominant source area during the rising limb of the melt hydrograph. Hysteresis was counterclockwise at hillslope sites, suggesting that hillslope drainage controlled the snowmelt recession. End member mixing analysis using Ca, Mg, Na, dissolved organic carbon (DOC), and Si showed that stream chemistry could be explained as a two-component mixture of groundwater high in base cations and an O-horizon/overland flow water high in DOC. The dominance of shallow flow paths during events was indicated by the high positive correlation of DOC with streamflow (r2 = 0.82). Despite the occurrence of transmissivity

  7. What would judgment and decision making research be like if we took a Bayesian approach to hypothesis testing?

    Directory of Open Access Journals (Sweden)

    William J. Matthews

    2011-12-01

    Full Text Available Judgment and decision making research overwhelmingly uses null hypothesis significance testing as the basis for statistical inference. This article examines an alternative, Bayesian approach which emphasizes the choice between two competing hypotheses and quantifies the balance of evidence provided by the data---one consequence of which is that experimental results may be taken to strongly favour the null hypothesis. We apply a recently-developed ``Bayesian $t$-test'' to existing studies of the anchoring effect in judgment, and examine how the change in approach affects both the tone of hypothesis testing and the substantive conclusions that one draws. We compare the Bayesian approach with Fisherian and Neyman-Pearson testing, examining its relationship to conventional $p$-values, the influence of effect size, and the importance of prior beliefs about the likely state of nature. The results give a sense of how Bayesian hypothesis testing might be applied to judgment and decision making research, and of both the advantages and challenges that a shift to this approach would entail.

  8. Testing Munk's hypothesis for submesoscale eddy generation using observations in the North Atlantic

    Science.gov (United States)

    Buckingham, Christian E.; Khaleel, Zammath; Lazar, Ayah; Martin, Adrian P.; Allen, John T.; Naveira Garabato, Alberto C.; Thompson, Andrew F.; Vic, Clément

    2017-08-01

    A high-resolution satellite image that reveals a train of coherent, submesoscale (6 km) vortices along the edge of an ocean front is examined in concert with hydrographic measurements in an effort to understand formation mechanisms of the submesoscale eddies. The infrared satellite image consists of ocean surface temperatures at ˜390 m resolution over the midlatitude North Atlantic (48.69°N, 16.19°W). Concomitant altimetric observations coupled with regular spacing of the eddies suggest the eddies result from mesoscale stirring, filamentation, and subsequent frontal instability. While horizontal shear or barotropic instability (BTI) is one mechanism for generating such eddies (Munk's hypothesis), we conclude from linear theory coupled with the in situ data that mixed layer or submesoscale baroclinic instability (BCI) is a more plausible explanation for the observed submesoscale vortices. Here we assume that the frontal disturbance remains in its linear growth stage and is accurately described by linear dynamics. This result likely has greater applicability to the open ocean, i.e., regions where the gradient Rossby number is reduced relative to its value along coasts and within strong current systems. Given that such waters comprise an appreciable percentage of the ocean surface and that energy and buoyancy fluxes differ under BTI and BCI, this result has wider implications for open-ocean energy/buoyancy budgets and parameterizations within ocean general circulation models. In summary, this work provides rare observational evidence of submesoscale eddy generation by BCI in the open ocean.Plain Language SummaryHere, we test Munk's theory for small-scale eddy generation using a unique set of satellite- and ship-based observations. We find that for one particular set of observations in the North Atlantic, the mechanism for eddy generation is not pure horizontal shear, as proposed by Munk et al. () and Munk (), but is instead vertical shear, or baroclinic instability

  9. In poor families, mothers' milk is richer for daughters than sons: a test of Trivers-Willard hypothesis in agropastoral settlements in Northern Kenya.

    Science.gov (United States)

    Fujita, Masako; Roth, Eric; Lo, Yun-Jia; Hurst, Carolyn; Vollner, Jennifer; Kendell, Ashley

    2012-09-01

    The Trivers-Willard hypothesis predicts the unequal parental investment between daughters and sons, depending on maternal condition and offspring reproductive potential. Specifically, in polygynous populations where males have higher reproductive variance than females, it predicts that mothers in good condition will invest more in sons, whereas mothers in poor condition will invest more in daughters. Previous studies testing this hypothesis focused on behavioral investment, whereas few examined biological investment. This study investigates the Trivers-Willard hypothesis on both behavioral and biological parental investment by examining breastfeeding frequencies and breast milk fat concentrations. Data from exclusively breastfeeding mothers in Northern Kenya were used to test hypotheses: Economically sufficient mothers will breastfeed sons more frequently than daughters, whereas poor mothers will breastfeed daughters more frequently than sons, and economically sufficient mothers will produce breast milk with higher fat concentration for sons than daughters, whereas poor mothers will produce breast milk with higher fat concentration for daughters than sons. Linear regression models were applied, using breastfeeding frequency or log-transformed milk fat as the dependent variable, and offspring's sex (son = 1/daughter = 0), socioeconomic status (higher = 1/lower = 0), and the sex-wealth interaction as the predictors, controlling for covariates. Our results only supported the milk fat hypothesis: infant's sex and socioeconomic status interacted (P = 0.014, n = 72) in their relation with milk fat concentration. The model estimated that economically sufficient mothers produced richer milk for sons than daughters (2.8 vs. 1.74 gm/dl) [corrected] while poor mothers produced richer milk for daughters than sons (2.6 vs. 2.3 gm/dl). Further research on milk constituents in relation to offspring's sex is warranted. Copyright © 2012 Wiley Periodicals, Inc.

  10. A test of the permanent income hypothesis on Czech voucher privatization

    Czech Academy of Sciences Publication Activity Database

    Hanousek, Jan; Tůma, Z.

    2002-01-01

    Roč. 10, č. 2 (2002), s. 235-254 ISSN 0967-0750 Institutional research plan: CEZ:AV0Z7085904 Keywords : Barro-Riccardian * equivalence * permanent income hypothesis Subject RIV: AH - Economics Impact factor: 0.897, year: 2002 http://search. ebscohost .com/login.aspx?direct=true&db=bth&AN=6844845&site=ehost-live

  11. Motor Resonance as a Function of Narrative Time: Further Tests of the Linguistic Focus Hypothesis

    Science.gov (United States)

    Zwaan, Rolf A.; Taylor, Lawrence J.; de Boer, Mirte

    2010-01-01

    Neuroimaging and behavioral studies have revealed involvement of the brain's motor system in language comprehension. The Linguistic-Focus Hypothesis [Taylor, L. J., & Zwaan, R. A. (2008). Motor resonance and linguistic focus. "Quarterly Journal of Experimental Psychology,61", 869-904.] postulates that engagement of the motor system during language…

  12. Assessing the Computational Potential of the Eschaton - Testing the Selfish Biocosm Hypothesis

    Science.gov (United States)

    Gardner, J. N.

    The Selfish Biocosm (SB) hypothesis asserts that the anthropic qualities which our universe exhibits can be explained as incidental consequences of a cosmic replication cycle in which a cosmologically extended bio- sphere supplies two of the essential elements of self-replication identified by von Neumann. It was previously suggested that the hypothesis implies (1) that the emergence of life and intelligence are key epigenetic thresholds in the cosmic replication cycle, strongly favored by the physical laws and constants which prevail in our particular universe and (2) that a falsifiable implication of the hypothesis is that the emergence of increas- ingly intelligent life is a robust phenomenon, strongly favored by the natural processes of evolution which result from the interplay of those laws and constants. Here I propose a further falsifiable implication of the SB hypothesis: that there exists a plausible final state of the cosmos which exhibits maximal computational potential. This predicted final state--the Omega Point or eschaton--appears to be not inconsistent with Lloyd's description of the ultimate computational device: a computer as powerful as the laws of physics will allow.

  13. Radio spectrum measurements of artificial ball lightning and testing the hypothesis on its plasmochemical nature

    Science.gov (United States)

    Kopeikin, V. V.

    2014-01-01

    Spectral measurements of radiowaves emitted by artificial ball lightning are presented. The measurements were carried out using two different facilities: a pulsed power generator (PPG) and a three-contour Tesla transformer. The results of these measurements confirm the hypothesis that ball lightning is a self-oscillator of high-voltage pulses in the radio range.

  14. A Test of the Stability of Punishment Hypothesis: The Case of California, 1851-1970.

    Science.gov (United States)

    Berk, Richard A.; And Others

    1981-01-01

    Examines data from California from the 1850 opening of the prison system to 1970. Finds no evidence to support the hypothesis that, for a given society over time and in the absence of major societal upheaval, the proportion of people subjected to punishment by the state closely approximates a constant. (Author/GC)

  15. A quantitative test of the size efficiency hypothesis by means of a physiologically structured model

    NARCIS (Netherlands)

    Hülsmann, S.; Rinke, K.; Mooij, W.M.

    2005-01-01

    According to the size-efficiency hypothesis (SEH) larger bodied cladocerans are better competitors for food than small bodied species. In environments with fish, however, the higher losses of the large bodied species due to size-selective predation may shift the balance in favor of the small bodied

  16. Tests of the Dynamic Field Theory and The Spatial Precision Hypothesis: Capturing a Qualitative Developmental Transition in Spatial Working Memory

    Science.gov (United States)

    Schutte, Anne R.; Spencer, John P.

    2009-01-01

    This study tested a dynamic field theory (DFT) of spatial working memory and an associated spatial precision hypothesis (SPH). Between 3 and 6 years of age, there is a qualitative shift in how children use reference axes to remember locations: 3-year-olds' spatial recall responses are biased toward reference axes after short memory delays, whereas…

  17. The Effect of Retention Interval Task Difficulty on Young Children's Prospective Memory: Testing the Intention Monitoring Hypothesis

    Science.gov (United States)

    Mahy, Caitlin E. V.; Moses, Louis J.

    2015-01-01

    The current study examined the impact of retention interval task difficulty on 4- and 5-year-olds' prospective memory (PM) to test the hypothesis that children periodically monitor their intentions during the retention interval and that disrupting this monitoring may result in poorer PM performance. In addition, relations among PM, working memory,…

  18. The Influence of Maternal Acculturation, Neighborhood Disadvantage, and Parenting on Chinese American Adolescents' Conduct Problems: Testing the Segmented Assimilation Hypothesis

    Science.gov (United States)

    Liu, Lisa L.; Lau, Anna S.; Chen, Angela Chia-Chen; Dinh, Khanh T.; Kim, Su Yeong

    2009-01-01

    Associations among neighborhood disadvantage, maternal acculturation, parenting and conduct problems were investigated in a sample of 444 Chinese American adolescents. Adolescents (54% female, 46% male) ranged from 12 to 15 years of age (mean age = 13.0 years). Multilevel modeling was employed to test the hypothesis that the association between…

  19. Is Variability in Mate Choice Similar for Intelligence and Personality Traits? Testing a Hypothesis about the Evolutionary Genetics of Personality

    Science.gov (United States)

    Stone, Emily A.; Shackelford, Todd K.; Buss, David M.

    2012-01-01

    This study tests the hypothesis presented by Penke, Denissen, and Miller (2007a) that condition-dependent traits, including intelligence, attractiveness, and health, are universally and uniformly preferred as characteristics in a mate relative to traits that are less indicative of condition, including personality traits. We analyzed…

  20. A Global comparison of surface soil characteristics across five cities: A test of the urban ecosystem convergence hypothesis.

    Science.gov (United States)

    Richard V. Pouyat; Ian D. Yesilonis; Miklos Dombos; Katalin Szlavecz; Heikki Setala; Sarel Cilliers; Erzsebet Hornung; D. Johan Kotze; Stephanie. Yarwood

    2015-01-01

    As part of the Global Urban Soil Ecology and Education Network and to test the urban ecosystem convergence hypothesis, we report on soil pH, organic carbon (OC), total nitrogen (TN), phosphorus (P), and potassium (K) measured in four soil habitat types (turfgrass, ruderal, remnant, and reference) in five metropolitan areas (Baltimore, Budapest,...

  1. Received social support and exercising: An intervention study to test the enabling hypothesis.

    Science.gov (United States)

    Rackow, Pamela; Scholz, Urte; Hornung, Rainer

    2015-11-01

    Received social support is considered important for health-enhancing exercise participation. The enabling hypothesis of social support suggests an indirect association of social support and exercising via constructs of self-regulation, such as self-efficacy. This study aimed at examining an expanded enabling hypothesis by examining effects of different kinds of social support (i.e., emotional and instrumental) on exercising not only via self-efficacy but also via self-monitoring and action planning. An 8-week online study was conducted. Participants were randomly assigned to an intervention or a control group. The intervention comprised finding and then exercising regularly with a new exercise companion. Intervention and control group effects were compared by a manifest multigroup model. Received emotional social support predicted self-efficacy, self-monitoring, and action planning in the intervention group. Moreover, received emotional social support was indirectly connected with exercise via the examined mediators. The indirect effect from received emotional social support via self-efficacy mainly contributed to the total effect. No direct or indirect effect of received instrumental social support on exercise emerged. In the control group, neither emotional nor instrumental social support was associated with any of the self-regulation constructs nor with exercise. Actively looking for a new exercise companion and exercising together seems to be beneficial for the promotion of received emotional and instrumental social support. Emotional support in turn promotes exercise by enabling better self-regulation, in particular self-efficacy. Statement of contribution What is already known on this subject? With the 'enabling hypothesis', Benight and Bandura (2004, Behav. Res. Ther., 42, 1129) claimed that social support indirectly affects behaviour via self-efficacy. Research in the domain of physical exercise has provided evidence for this enabling hypothesis on a

  2. Comparative vs ontogenetic paradigms for tests of the intrinsic mutagenesis hypothesis of aging

    Energy Technology Data Exchange (ETDEWEB)

    Sacher, G.A.

    1979-01-01

    This paper examines certain aspects of the biology of longevity and aging that bear on the role of DNA in the ontogenetic aging process, and on the genetic basis for the differences of longevity among mammal species. (PCS)

  3. Testing the "Mudball Earth" Hypothesis: Are Neoproterozoic Glacial Deposits Capped with Supraglacial Dust?

    Science.gov (United States)

    Goodman, J. C.; Alvim Lage, C.

    2014-12-01

    The Snowball Earth hypothesis has inspired several variants which may help to explain some of the great mysteries of the Neoproterozoic glaciations. One of these, the "Mudball Earth", proposes that as the Earth remained completely frozen for millions of years, a layer of dust accumulated on the ice surface. This dust layer would darken the planet, making it easier for the Earth to escape from the highly stable snowball climate state. This hypothesis is testable: after the ice melted at the end of a glacial era, this dust would sink to the bottom of the ocean, possibly forming a distinct clay, mud, or silt layer on the top of the glacial till deposits: this "clay drape" would then be covered by the cap carbonates that mark a return to warm climate. Sublimation and ice flow during the glacial episode should make this layer thicker at the equator and thinner or absent in the poles. Is this clay layer actually present in the rock record? Is it more prevalent at the paleoequator, as predicted? A clay drape has been noticed anecdotally, but no global survey has been done to date. We conducted a thorough literature review of all sites where Neoproterozoic glacial diamictites have been observed, identifying the type of rock that lies between the diamictite and the postglacial cap carbonate, when present, during both Sturtian and Marinoan glacial periods. Only a few publications identify a distinct clay/silt/mud layer that might represent weathered dust. These sites are not grouped by paleolatitude in any obvious way. With access only to published reports, we cannot determine whether such a layer is absent, went unreported, or was misinterpreted by us. With this work we hope to attract the attention of Neoproterozoic field geologists, inviting them to comment on the presence or absence of strata which could confirm or reject the "Mudball" hypothesis.

  4. Testing the Binary Hypothesis: Pulsar Timing Constraints on Supermassive Black Hole Binary Candidates

    Science.gov (United States)

    Sesana, Alberto; Haiman, Zoltán; Kocsis, Bence; Kelley, Luke Zoltan

    2018-03-01

    The advent of time domain astronomy is revolutionizing our understanding of the universe. Programs such as the Catalina Real-time Transient Survey (CRTS) or the Palomar Transient Factory (PTF) surveyed millions of objects for several years, allowing variability studies on large statistical samples. The inspection of ≈250 k quasars in CRTS resulted in a catalog of 111 potentially periodic sources, put forward as supermassive black hole binary (SMBHB) candidates. A similar investigation on PTF data yielded 33 candidates from a sample of ≈35 k quasars. Working under the SMBHB hypothesis, we compute the implied SMBHB merger rate and we use it to construct the expected gravitational wave background (GWB) at nano-Hz frequencies, probed by pulsar timing arrays (PTAs). After correcting for incompleteness and assuming virial mass estimates, we find that the GWB implied by the CRTS sample exceeds the current most stringent PTA upper limits by almost an order of magnitude. After further correcting for the implicit bias in virial mass measurements, the implied GWB drops significantly but is still in tension with the most stringent PTA upper limits. Similar results hold for the PTF sample. Bayesian model selection shows that the null hypothesis (whereby the candidates are false positives) is preferred over the binary hypothesis at about 2.3σ and 3.6σ for the CRTS and PTF samples respectively. Although not decisive, our analysis highlights the potential of PTAs as astrophysical probes of individual SMBHB candidates and indicates that the CRTS and PTF samples are likely contaminated by several false positives.

  5. Beyond Correlation in the Detection of Climate Change Impacts: Testing a Mechanistic Hypothesis for Climatic Influence on Sockeye Salmon (Oncorhynchus nerka) Productivity.

    Science.gov (United States)

    Tillotson, Michael D; Quinn, Thomas P

    2016-01-01

    Detecting the biological impacts of climate change is a current focus of ecological research and has important applications in conservation and resource management. Owing to a lack of suitable control systems, measuring correlations between time series of biological attributes and hypothesized environmental covariates is a common method for detecting such impacts. These correlative approaches are particularly common in studies of exploited fish species because rich biological time-series data are often available. However, the utility of species-environment relationships for identifying or predicting biological responses to climate change has been questioned because strong correlations often deteriorate as new data are collected. Specifically stating and critically evaluating the mechanistic relationship(s) linking an environmental driver to a biological response may help to address this problem. Using nearly 60 years of data on sockeye salmon from the Kvichak River, Alaska we tested a mechanistic hypothesis linking water temperatures experienced during freshwater rearing to population productivity by modeling a series of intermediate, deterministic relationships and evaluating temporal trends in biological and environmental time-series. We found that warming waters during freshwater rearing have profoundly altered patterns of growth and life history in this population complex yet there has been no significant correlation between water temperature and metrics of productivity commonly used in fisheries management. These findings demonstrate that pairing correlative approaches with careful consideration of the mechanistic links between populations and their environments can help to both avoid spurious correlations and identify biologically important, but not statistically significant relationships, and ultimately producing more robust conclusions about the biological impacts of climate change.

  6. Beyond Correlation in the Detection of Climate Change Impacts: Testing a Mechanistic Hypothesis for Climatic Influence on Sockeye Salmon (Oncorhynchus nerka Productivity.

    Directory of Open Access Journals (Sweden)

    Michael D Tillotson

    Full Text Available Detecting the biological impacts of climate change is a current focus of ecological research and has important applications in conservation and resource management. Owing to a lack of suitable control systems, measuring correlations between time series of biological attributes and hypothesized environmental covariates is a common method for detecting such impacts. These correlative approaches are particularly common in studies of exploited fish species because rich biological time-series data are often available. However, the utility of species-environment relationships for identifying or predicting biological responses to climate change has been questioned because strong correlations often deteriorate as new data are collected. Specifically stating and critically evaluating the mechanistic relationship(s linking an environmental driver to a biological response may help to address this problem. Using nearly 60 years of data on sockeye salmon from the Kvichak River, Alaska we tested a mechanistic hypothesis linking water temperatures experienced during freshwater rearing to population productivity by modeling a series of intermediate, deterministic relationships and evaluating temporal trends in biological and environmental time-series. We found that warming waters during freshwater rearing have profoundly altered patterns of growth and life history in this population complex yet there has been no significant correlation between water temperature and metrics of productivity commonly used in fisheries management. These findings demonstrate that pairing correlative approaches with careful consideration of the mechanistic links between populations and their environments can help to both avoid spurious correlations and identify biologically important, but not statistically significant relationships, and ultimately producing more robust conclusions about the biological impacts of climate change.

  7. Test of the neurolinguistic programming hypothesis that eye-movements relate to processing imagery.

    Science.gov (United States)

    Wertheim, E H; Habib, C; Cumming, G

    1986-04-01

    Bandler and Grinder's hypothesis that eye-movements reflect sensory processing was examined. 28 volunteers first memorized and then recalled visual, auditory, and kinesthetic stimuli. Changes in eye-positions during recall were videotaped and categorized by two raters into positions hypothesized by Bandler and Grinder's model to represent visual, auditory, and kinesthetic recall. Planned contrast analyses suggested that visual stimulus items, when recalled, elicited significantly more upward eye-positions and stares than auditory and kinesthetic items. Auditory and kinesthetic items, however, did not elicit more changes in eye-position hypothesized by the model to represent auditory and kinesthetic recall, respectively.

  8. PERSONALIZED HYPOTHESIS TESTS FOR DETECTING MEDICATION RESPONSE IN PARKINSON DISEASE PATIENTS USING iPHONE SENSOR DATA.

    Science.gov (United States)

    Chaibub Neto, Elias; Bot, Brian M; Perumal, Thanneer; Omberg, Larsson; Guinney, Justin; Kellen, Mike; Klein, Arno; Friend, Stephen H; Trister, Andrew D

    2016-01-01

    We propose hypothesis tests for detecting dopaminergic medication response in Parkinson disease patients, using longitudinal sensor data collected by smartphones. The processed data is composed of multiple features extracted from active tapping tasks performed by the participant on a daily basis, before and after medication, over several months. Each extracted feature corresponds to a time series of measurements annotated according to whether the measurement was taken before or after the patient has taken his/her medication. Even though the data is longitudinal in nature, we show that simple hypothesis tests for detecting medication response, which ignore the serial correlation structure of the data, are still statistically valid, showing type I error rates at the nominal level. We propose two distinct personalized testing approaches. In the first, we combine multiple feature-specific tests into a single union-intersection test. In the second, we construct personalized classifiers of the before/after medication labels using all the extracted features of a given participant, and test the null hypothesis that the area under the receiver operating characteristic curve of the classifier is equal to 1/2. We compare the statistical power of the personalized classifier tests and personalized union-intersection tests in a simulation study, and illustrate the performance of the proposed tests using data from mPower Parkinsons disease study, recently launched as part of Apples ResearchKit mobile platform. Our results suggest that the personalized tests, which ignore the longitudinal aspect of the data, can perform well in real data analyses, suggesting they might be used as a sound baseline approach, to which more sophisticated methods can be compared to.

  9. Secretive food concocting in binge eating: test of a famine hypothesis.

    Science.gov (United States)

    Boggiano, Mary M; Turan, Bulent; Maldonado, Christine R; Oswald, Kimberly D; Shuman, Ellen S

    2013-04-01

    Food concocting, or making strange food mixtures, is well documented in the famine and experimental semistarvation literature and appears anecdotally in rare descriptions of eating disorder (ED) patients but has never been scientifically investigated. Here we do so in the context of binge-eating using a "famine hypothesis of concocting." A sample of 552 adults varying in binge eating and dieting traits completed a Concocting Survey created for this study. Exploratory ED groups were created to obtain predictions as to the nature of concocting in clinical populations. Binge eating predicted the 24.6% of participants who reported having ever concocted but dietary restraint, independently, even after controlling for binge eating, predicted its frequency and salience. Craving was the main motive. Emotions while concocting mirrored classic high-arousal symptoms associated with drug use; while eating the concoctions were associated with intensely negative/self-deprecating emotions. Concocting prevalence and salience was greater in the anorexia > bulimia > BED > no ED groups, consistent with their respectively incrementing dieting scores. Concocting distinguishes binge eating from other overeating and, consistent with the famine hypothesis, is accounted for by dietary restraint. Unlike its adaptive function in famine, concocting could worsen binge-eating disorders by increasing negative effect, shame, and secrecy. Its assessment in these disorders may prove therapeutically valuable. Copyright © 2012 Wiley Periodicals, Inc.

  10. Test of Martin’s overkill hypothesis using radiocarbon dates on extinct megafauna

    Science.gov (United States)

    Surovell, Todd A.; Pelton, Spencer R.; Anderson-Sprecher, Richard; Myers, Adam D.

    2016-01-01

    Following Martin [Martin PS (1973) Science 179:969–974], we propose the hypothesis that the timing of human arrival to the New World can be assessed by examining the ecological impacts of a small population of people on extinct Pleistocene megafauna. To that end, we compiled lists of direct radiocarbon dates on paleontological specimens of extinct genera from North and South America with the expectation that the initial decline of extinct megafauna should correspond in time with the initial evidence for human colonization and that those declines should occur first in eastern Beringia, next in the contiguous United States, and last in South America. Analyses of spacings and frequency distributions of radiocarbon dates for each region support the idea that the extinction event first commenced in Beringia, roughly 13,300–15,000 BP. For the United States and South America, extinctions commenced considerably later but were closely spaced in time. For the contiguous United States, extinction began at ca. 12,900–13,200 BP, and at ca. 12,600–13,900 BP in South America. For areas south of Beringia, these estimates correspond well with the first significant evidence for human presence and are consistent with the predictions of the overkill hypothesis. PMID:26504205

  11. Test of Martin's overkill hypothesis using radiocarbon dates on extinct megafauna.

    Science.gov (United States)

    Surovell, Todd A; Pelton, Spencer R; Anderson-Sprecher, Richard; Myers, Adam D

    2016-01-26

    Following Martin [Martin PS (1973) Science 179:969-974], we propose the hypothesis that the timing of human arrival to the New World can be assessed by examining the ecological impacts of a small population of people on extinct Pleistocene megafauna. To that end, we compiled lists of direct radiocarbon dates on paleontological specimens of extinct genera from North and South America with the expectation that the initial decline of extinct megafauna should correspond in time with the initial evidence for human colonization and that those declines should occur first in eastern Beringia, next in the contiguous United States, and last in South America. Analyses of spacings and frequency distributions of radiocarbon dates for each region support the idea that the extinction event first commenced in Beringia, roughly 13,300-15,000 BP. For the United States and South America, extinctions commenced considerably later but were closely spaced in time. For the contiguous United States, extinction began at ca. 12,900-13,200 BP, and at ca. 12,600-13,900 BP in South America. For areas south of Beringia, these estimates correspond well with the first significant evidence for human presence and are consistent with the predictions of the overkill hypothesis.

  12. Secretive Food Concocting in Binge Eating: Test of a Famine Hypothesis

    Science.gov (United States)

    Boggiano, Mary M.; Turan, Bulent; Maldonado, Christine R.; Oswald, Kimberly D.; Shuman, Ellen S.

    2016-01-01

    Objective Food concocting, or making strange food mixtures, is well documented in the famine and experimental semistarvation literature and appears anecdotally in rare descriptions of eating disorder (ED) patients but has never been scientifically investigated. Here we do so in the context of binge-eating using a “famine hypothesis of concocting.” Method A sample of 552 adults varying in binge eating and dieting traits completed a Concocting Survey created for this study. Exploratory ED groups were created to obtain predictions as to the nature of concocting in clinical populations. Results Binge eating predicted the 24.6% of participants who reported having ever concocted but dietary restraint, independently, even after controlling for binge eating, predicted its frequency and salience. Craving was the main motive. Emotions while concocting mirrored classic high-arousal symptoms associated with drug use; while eating the concoctions were associated with intensely negative/self-deprecating emotions. Concocting prevalence and salience was greater in the anorexia > bulimia > BED > no ED groups, consistent with their respectively incrementing dieting scores. Discussion Concocting distinguishes binge eating from other overeating and, consistent with the famine hypothesis, is accounted for by dietary restraint. Unlike its adaptive function in famine, concocting could worsen binge-eating disorders by increasing negative effect, shame, and secrecy. Its assessment in these disorders may prove therapeutically valuable. PMID:23255044

  13. Ploidy evolution in the yeast Saccharomyces cerevisiae: a test of the nutrient limitation hypothesis.

    Science.gov (United States)

    Mable, B K

    2001-01-08

    The nutrient limitation hypothesis provides a nongenetic explanation for the evolution of life cycles that retain both haploid and diploid phases: differences in nutrient requirements and uptake allow haploids to override the potential genetic advantages provided by diploidy under certain nutrient limiting conditions. The relative fitness of an isogenic series of haploid, diploid and tetraploid yeast cells (Saccharomyces cerevisiae), which were also equivalent at the mating type locus, was measured. Fitness was measured both by growth rate against a common competitor and by intrinsic growth rate in isolated cultures, under four environmental conditions: (1) rich medium (YPD) at the preferred growth temperature (30 °C); (2) nutrient poor medium (MM) at 30 °C; (3) YPD at a nonpreferred temperature (37 °C); and (4) MM at 37 °C. In contrast to the predictions of the nutrient limitation hypothesis, haploids grew significantly faster than diploids under nutrient rich conditions, but there were no apparent differences between them when fitness was determined by relative competitive ability. In addition, temperature affected the relative growth of haploids and diploids, with haploids growing proportionately faster at higher temperatures. Tetraploids performed very poorly under all conditions compared. Cell geometric parameters were not consistent predictors of fitness under the conditions measured.

  14. Health Effects of High Radon Environments in Central Europe: Another Test for the LNT Hypothesis?

    Science.gov (United States)

    Becker, Klaus

    2003-01-01

    Bechterew, radon treatments are beneficial, with the positive effect lasting until at least 6 months after the normally 3-week treatment by inhalation or bathes. Studies on the mechanism of these effects are progressing. In other cases of extensive use of radon treatment for a wide spectrum of various diseases, for example, in the former Soviet Union, the positive results are not so well established. However, according to a century of radon treatment experience (after millenniums of unknown radon therapy), in particular in Germany and Austria, the positive medical effects for some diseases far exceed any potential detrimental health effects.The total amount of available data in this field is too large to be covered in a brief review. Therefore, less known - in particular recent - work from Central Europe has been analyzed in an attempt to summarize new developments and trends. This includes cost/benefit aspects of radon reduction programs. As a test case for the LNT (linear non-threshold) hypothesis and possible biopositive effects of low radiation exposures, the data support a nonlinear human response to low and medium-level radon exposures.

  15. Combining multiple hypothesis testing and affinity propagation clustering leads to accurate, robust and sample size independent classification on gene expression data

    Directory of Open Access Journals (Sweden)

    Sakellariou Argiris

    2012-10-01

    Full Text Available Abstract Background A feature selection method in microarray gene expression data should be independent of platform, disease and dataset size. Our hypothesis is that among the statistically significant ranked genes in a gene list, there should be clusters of genes that share similar biological functions related to the investigated disease. Thus, instead of keeping N top ranked genes, it would be more appropriate to define and keep a number of gene cluster exemplars. Results We propose a hybrid FS method (mAP-KL, which combines multiple hypothesis testing and affinity propagation (AP-clustering algorithm along with the Krzanowski & Lai cluster quality index, to select a small yet informative subset of genes. We applied mAP-KL on real microarray data, as well as on simulated data, and compared its performance against 13 other feature selection approaches. Across a variety of diseases and number of samples, mAP-KL presents competitive classification results, particularly in neuromuscular diseases, where its overall AUC score was 0.91. Furthermore, mAP-KL generates concise yet biologically relevant and informative N-gene expression signatures, which can serve as a valuable tool for diagnostic and prognostic purposes, as well as a source of potential disease biomarkers in a broad range of diseases. Conclusions mAP-KL is a data-driven and classifier-independent hybrid feature selection method, which applies to any disease classification problem based on microarray data, regardless of the available samples. Combining multiple hypothesis testing and AP leads to subsets of genes, which classify unknown samples from both, small and large patient cohorts with high accuracy.

  16. A Powerful Test of the Autoregressive Unit Root Hypothesis Based on a Tuning Parameter Free Statistic

    DEFF Research Database (Denmark)

    Nielsen, Morten Ørregaard

    This paper presents a family of simple nonparametric unit root tests indexed by one parameter, d, and containing Breitung's (2002) test as the special case d = 1. It is shown that (i) each member of the family with d > 0 is consistent, (ii) the asymptotic distribution depends on d, and thus...... reflects the parameter chosen to implement the test, and (iii) since the asymptotic distribution depends on d and the test remains consistent for all d > 0, it is possible to analyze the power of the test for different values of d. The usual Phillips-Perron or Dickey-Fuller type tests are indexed...... by bandwidth, lag length, etc., but have none of these three properties. It is shown that members of the family with d test, and when d is small the asymptotic local power of the proposed nonparametric test is relatively close to the parametric...

  17. Gender differences in emotion perception and self-reported emotional intelligence: A test of the emotion sensitivity hypothesis

    OpenAIRE

    Fischer, Agneta H.; Kret, Mariska E.; Broekens, Joost

    2018-01-01

    Previous meta-analyses and reviews on gender differences in emotion recognition have shown a small to moderate female advantage. However, inconsistent evidence from recent studies has raised questions regarding the implications of different methodologies, stimuli, and samples. In the present research based on a community sample of more than 5000 participants, we tested the emotional sensitivity hypothesis, stating that women are more sensitive to perceive subtle, i.e. low intense or ambiguous...

  18. Testing the Hypothesis of Biofilm as a Source for Soft Tissue and Cell-Like Structures Preserved in Dinosaur Bone

    OpenAIRE

    Schweitzer, Mary Higby; Moyer, Alison E.; Zheng, Wenxia

    2016-01-01

    Recovery of still-soft tissue structures, including blood vessels and osteocytes, from dinosaur bone after demineralization was reported in 2005 and in subsequent publications. Despite multiple lines of evidence supporting an endogenous source, it was proposed that these structures arose from contamination from biofilm-forming organisms. To test the hypothesis that soft tissue structures result from microbial invasion of the fossil bone, we used two different biofilm-forming microorganisms to...

  19. Effects of native biodiversity on grape loss of four castes: testing the biotic resistance hypothesis

    OpenAIRE

    M. Nereu; M. Nereu; R. H. Heleno; F. Lopez-Núñez; M. Agostinho; J. A. Ramos

    2018-01-01

    Management of agricultural landscapes can influence the biodiversity and the ecological services provided by these ecosystems, such as natural biological pest control. Viticulture is a very important economic activity in most countries with Mediterranean climate, often shaping their landscapes and culture. Grape production is affected by a number of pests and diseases, and farmers use prophylactic and response-driven pesticides to control these pests. Here we quantified the ...

  20. First-order correct bootstrap support adjustments for splits that allow hypothesis testing when using maximum likelihood estimation.

    Science.gov (United States)

    Susko, Edward

    2010-07-01

    The most frequent measure of phylogenetic uncertainty for splits is bootstrap support. Although large bootstrap support intuitively suggests that a split in a tree is well supported, it has not been clear how large bootstrap support needs to be to conclude that there is significant evidence that a hypothesized split is present. Indeed, recent work has shown that bootstrap support is not first-order correct and thus cannot be directly used for hypothesis testing. We present methods that adjust bootstrap support values in a maximum likelihood (ML) setting so that they have an interpretation corresponding to P values in conventional hypothesis testing; for instance, adjusted bootstrap support larger than 95% occurs only 5% of the time if the split is not present. Through examples and simulation settings, it is found that adjustments always increase the level of support. We also find that the nature of the adjustment is fairly constant across parameter settings. Finally, we consider adjustments that take into account the data-dependent nature of many hypotheses about splits: the hypothesis that they are present is being tested because they are in the tree estimated through ML. Here, in contrast, we find that bootstrap probability often needs to be adjusted downwards.

  1. Personality and Behavior in Social Dilemmas: Testing the Situational Strength Hypothesis and the Role of Hypothetical Versus Real Incentives.

    Science.gov (United States)

    Lozano, José H

    2016-02-01

    Previous research aimed at testing the situational strength hypothesis suffers from serious limitations regarding the conceptualization of strength. In order to overcome these limitations, the present study attempts to test the situational strength hypothesis based on the operationalization of strength as reinforcement contingencies. One dispositional factor of proven effect on cooperative behavior, social value orientation (SVO), was used as a predictor of behavior in four social dilemmas with varying degree of situational strength. The moderating role of incentive condition (hypothetical vs. real) on the relationship between SVO and behavior was also tested. One hundred undergraduates were presented with the four social dilemmas and the Social Value Orientation Scale. One-half of the sample played the social dilemmas using real incentives, whereas the other half used hypothetical incentives. Results supported the situational strength hypothesis in that no behavioral variability and no effect of SVO on behavior were found in the strongest situation. However, situational strength did not moderate the effect of SVO on behavior in situations where behavior showed variability. No moderating effect was found for incentive condition either. The implications of these results for personality theory and assessment are discussed. © 2014 Wiley Periodicals, Inc.

  2. Biological assays for aquatic toxicity testing

    CSIR Research Space (South Africa)

    Slabbert, JL

    1999-10-01

    Full Text Available A number of aquatic toxicity tests have been established for South African use, which include fish and Daphnia lethality tests, microbiotests, and short-term chronic tests. Studies on effluents and surface waters showed that all the tests have a...

  3. Infant temperament, parenting, and externalizing behavior in first grade: a test of the differential susceptibility hypothesis.

    Science.gov (United States)

    Bradley, Robert H; Corwyn, Robert F

    2008-02-01

    This study examines the differential susceptibility hypothesis as it pertains to relations between infant temperament, parenting, and behavior problems in first grade. Data from the NICHD Study of Early Child Care were used in a series of hierarchical regression analyses focused on interactions between three aspects of parenting (harshness, sensitivity, productive activity) and temperament as they affect teacher-reported externalizing behavior in first grade. Step #1 included family income-to-needs, maternal education, gender, life events, and amount of child care as control variables, plus infant temperament and the three parenting variables. Step #2 included a single interaction term, the interaction between one of the key parenting variables and child temperament. Results showed stronger relations between maternal sensitivity and behavior problems for children with difficult temperaments. Likewise, relations between opportunities for productivity and behavior problems were stronger for children with difficult temperaments. Trends were in the same direction for harsh parenting but did not quite reach statistical significance. Having access to experiences that promote coping and build self-regulatory capacities seems particularly valuable for children with difficult temperaments.

  4. Eating Disorders and Intrasexual Competition: Testing an Evolutionary Hypothesis among Young Women

    Science.gov (United States)

    Abed, Riadh; Mehta, Sunil; Figueredo, Aurelio José; Aldridge, Sarah; Balson, Hannah; Meyer, Caroline; Palmer, Robert

    2012-01-01

    The sexual competition hypothesis (SCH) contends that intense female intrasexual competition (ISC) is the ultimate cause of eating disorders. The SCH explains the phenomenon of the pursuit of thinness as an adaptation to ISC in the modern environment. It argues that eating disorders are pathological phenomena that arise from the mismatch between the modern environment and the inherited female adaptations for ISC. The present study has two aims. The first is to examine the relationship between disordered eating behavior (DEB) and ISC in a sample of female undergraduates. The second is to establish whether there is any relationship between disordered eating behavior and life history (LH) strategy. Participants completed a battery of questionnaires examining eating-related attitudes and behaviors, ISC, and LH strategy. A group of 206 female undergraduates were recruited. A structural equation model was constructed to analyze the data. ISC for mates was significantly associated with DEB, as predicted by the SCH. DEB was found to be predicted by fast LH strategy, which was only partially mediated by the SCH. The results of this study are supportive of the SCH and justify research on a clinical sample. PMID:22566764

  5. Men's preference for women's facial features: testing homogamy and the paternity uncertainty hypothesis.

    Science.gov (United States)

    Bovet, Jeanne; Barthes, Julien; Durand, Valérie; Raymond, Michel; Alvergne, Alexandra

    2012-01-01

    Male mate choice might be based on both absolute and relative strategies. Cues of female attractiveness are thus likely to reflect both fitness and reproductive potential, as well as compatibility with particular male phenotypes. In humans, absolute clues of fertility and indices of favorable developmental stability are generally associated with increased women's attractiveness. However, why men exhibit variable preferences remains less studied. Male mate choice might be influenced by uncertainty of paternity, a selective factor in species where the survival of the offspring depends on postnatal paternal care. For instance, in humans, a man might prefer a woman with recessive traits, thereby increasing the probability that his paternal traits will be visible in the child and ensuring paternity. Alternatively, attractiveness is hypothesized to be driven by self-resembling features (homogamy), which would reduce outbreeding depression. These hypotheses have been simultaneously evaluated for various facial traits using both real and artificial facial stimuli. The predicted preferences were then compared to realized mate choices using facial pictures from couples with at least 1 child. No evidence was found to support the paternity uncertainty hypothesis, as recessive features were not preferred by male raters. Conversely, preferences for self-resembling mates were found for several facial traits (hair and eye color, chin dimple, and thickness of lips and eyebrows). Moreover, realized homogamy for facial traits was also found in a sample of long-term mates. The advantages of homogamy in evolutionary terms are discussed.

  6. Men's preference for women's facial features: testing homogamy and the paternity uncertainty hypothesis.

    Directory of Open Access Journals (Sweden)

    Jeanne Bovet

    Full Text Available Male mate choice might be based on both absolute and relative strategies. Cues of female attractiveness are thus likely to reflect both fitness and reproductive potential, as well as compatibility with particular male phenotypes. In humans, absolute clues of fertility and indices of favorable developmental stability are generally associated with increased women's attractiveness. However, why men exhibit variable preferences remains less studied. Male mate choice might be influenced by uncertainty of paternity, a selective factor in species where the survival of the offspring depends on postnatal paternal care. For instance, in humans, a man might prefer a woman with recessive traits, thereby increasing the probability that his paternal traits will be visible in the child and ensuring paternity. Alternatively, attractiveness is hypothesized to be driven by self-resembling features (homogamy, which would reduce outbreeding depression. These hypotheses have been simultaneously evaluated for various facial traits using both real and artificial facial stimuli. The predicted preferences were then compared to realized mate choices using facial pictures from couples with at least 1 child. No evidence was found to support the paternity uncertainty hypothesis, as recessive features were not preferred by male raters. Conversely, preferences for self-resembling mates were found for several facial traits (hair and eye color, chin dimple, and thickness of lips and eyebrows. Moreover, realized homogamy for facial traits was also found in a sample of long-term mates. The advantages of homogamy in evolutionary terms are discussed.

  7. Testing the water hypothesis: Quantitative morphological analysis of terrestrial and martian mid-latitude gullies

    Science.gov (United States)

    Hobbs, S. W.; Paull, D. J.; Clarke, J. D. A.

    2017-10-01

    Although Martian gullies resemble terrestrial counterparts, two conflicting hypotheses exist for their formation still invoke fluvial processes on the one hand or lubricated CO2 flows on the other. In this work we compared the quantitative morphology of terrestrial gullies, known to have formed by liquid water, and mid-latitude Martian gullies in the Martian southern hemisphere. We also compared these results with measurements of Martian dry ravines adjacent to the gullies. Our results show a similarity between Martian and terrestrial gully formation, supporting the hypothesis that liquid water was involved in their erosion. Our results show dry ravines differ morphologically from gullies, further suggesting fluidised flows as a likely origin of the latter. Variations in the relationships across various terrestrial and Martian gullies indicate the significance of local environmental and geological conditions. Our work supports the idea that Martian gullies may not have been formed by just one single process but may have evolved through a more complex interaction of processes and environment.

  8. Testing the self-medication hypothesis of depression and aggression in cannabis-dependent subjects.

    Science.gov (United States)

    Arendt, Mikkel; Rosenberg, Raben; Fjordback, Lone; Brandholdt, Jack; Foldager, Leslie; Sher, Leo; Munk-Jørgensen, Povl

    2007-07-01

    A self-medication hypothesis has been proposed to explain the association between cannabis use and psychiatric and behavioral problems. However, little is known about the reasons for use and reactions while intoxicated in cannabis users who suffer from depression or problems controlling violent behavior. We assessed 119 cannabis-dependent subjects using the Schedules of Clinical Assessment in Neuropsychiatry (SCAN), parts of the Addiction Severity Index (ASI), and questionnaires on reasons for cannabis use and reactions to cannabis use while intoxicated. Participants with lifetime depression and problems controlling violent behavior were compared to subjects without such problems. Validity of the groupings was corroborated by use of a psychiatric treatment register, previous use of psychotropic medication and convictions for violence. Subjects with lifetime depression used cannabis for the same reasons as others. While under the influence of cannabis, they more often experienced depression, sadness, anxiety and paranoia, and they were less likely to report happiness or euphoria. Participants reporting problems controlling violent behavior more often used cannabis to decrease aggression, decrease suspiciousness, and for relaxation; while intoxicated they more often reacted with aggression. Subjects with prior depression do not use cannabis as a mean of self-medication. They are more likely to experience specific increases of adverse symptoms while under the influence of cannabis, and are less likely to experience specific symptom relief. There is some evidence that cannabis is used as a means of self-medication for problems controlling aggression.

  9. Testing the growth rate hypothesis in vascular plants with above- and below-ground biomass.

    Directory of Open Access Journals (Sweden)

    Qiang Yu

    Full Text Available The growth rate hypothesis (GRH proposes that higher growth rate (the rate of change in biomass per unit biomass, μ is associated with higher P concentration and lower C:P and N:P ratios. However, the applicability of the GRH to vascular plants is not well-studied and few studies have been done on belowground biomass. Here we showed that, for aboveground, belowground and total biomass of three study species, μ was positively correlated with N:C under N limitation and positively correlated with P:C under P limitation. However, the N:P ratio was a unimodal function of μ, increasing for small values of μ, reaching a maximum, and then decreasing. The range of variations in μ was positively correlated with variation in C:N:P stoichiometry. Furthermore, μ and C:N:P ranges for aboveground biomass were negatively correlated with those for belowground. Our results confirm the well-known association of growth rate with tissue concentration of the limiting nutrient and provide empirical support for recent theoretical formulations.

  10. Cross-Border Mergers and Acquisitions in China: A Test of the Free Cash Flow Hypothesis

    Directory of Open Access Journals (Sweden)

    Yane Chandera

    2014-08-01

    Full Text Available This research investigates whether Chinese cross-border investments have positive impact onshareholders wealth and whether the amount of bidders’ free cash flow influences the shareholderreturns resulted from the acquisitions. The sample is based on 77 top Chinese cross-border investmentsduring the years 2005-2009 with each deal value of minimum US$100 million. The assessmentsof acquisition abnormal returns are based on the event study methodology (Brown & Warner, 1985.Cross-sectional regression analysis is used to determine the bidding firms factors which significantlyaffect the returns. Factors are examined using OLS with White’s heteroscedasticity-corrected standarderrors, since the assumption of homoscedasticity is likely to be violated. The study proves Chinesecross- border acquisitions result in positive abnormal returns which is consistent with synergyhypothesis. The amount of bidders’ free cash flow is also found to be marginally but positively associatedwith shareholders return which is consistent with Myers and Majluf’s pecking order hypothesisbut unsupportive of Jensen’s free cash flow hypothesis.

  11. Why Do Fast-Growing Bacteria Enter Overflow Metabolism? Testing the Membrane Real Estate Hypothesis.

    Science.gov (United States)

    Szenk, Mariola; Dill, Ken A; de Graff, Adam M R

    2017-08-23

    Bacteria and other cells show a puzzling behavior. At high growth rates, E. coli switch from respiration (which is ATP-efficient) to using fermentation for additional ATP (which is inefficient). This overflow metabolism results in a several-fold decrease in ATP produced per glucose molecule provided as food. By integrating diverse types of experimental data into a simple biophysical model, we give evidence that this onset is the result of the membrane real estate hypothesis: Fast growth drives cells to be bigger, reducing their surface-to-volume ratios. This decreases the membrane area available for respiratory proteins despite growing demand, causing increased crowding. Only when respiratory proteins reach their crowding limit does the cell activate fermentation, since fermentation allows faster ATP production per unit membrane area. Surface limitation thus creates a Pareto trade-off between membrane efficiency and ATP yield that links metabolic choice to the size and shape of a bacterial cell. By exploring the predictions that emerge from this trade-off, we show how consideration of molecular structures, energetics, rates, and equilibria can provide important insight into cellular behavior. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Can retinal adhesion mechanisms determine cell-sorting patterns: a test of the differential adhesion hypothesis.

    Science.gov (United States)

    Thomas, W A; Yancey, J

    1988-05-01

    Embryonic chick neural retina cells possess two classes of adhesion mechanism, one Ca2+-independent, one Ca2+-dependent, responsible for short-term cell aggregation. This study investigates the role of these mechanisms in the long-term cell sorting potentially relevant to in vivo histogenesis. Retina cells are prepared either with both (E cells) or with only one mechanism (TC cells, CD; LTE cells, CI), respectively. The two types of cell preparations are differentially labelled using fluorescein or rhodamine isothiocyanate, mixed and allowed to aggregate in the presence or absence of cycloheximide at 0.5 microgram ml-1 to retard metabolic recovery of the removed adhesive mechanism. When observed by fluorescence and phase-contrast microscopy, the aggregates formed in cycloheximide show cell sorting, the cells with both mechanisms assuming a more interior position relative to those with a single adhesion mechanism. In parallel hanging-drop experiments, preformed aggregates of cells with a single adhesion mechanism are seen to spread upon aggregates of cells with both mechanisms. No sorting occurs amongst cells from a given stage prepared using any single dissociation protocol. The observed cell sorting would thus seem to derive exclusively from differential cell adhesiveness dependent upon the different dissociation conditions and maintained in the presence of cycloheximide. The experiments support the hypothesis that the dual CI and CD adhesion mechanisms in question can play a central role in governing cell-sorting behaviour during normal histogenesis.

  13. Eating disorders and intrasexual competition: testing an evolutionary hypothesis among young women.

    Science.gov (United States)

    Abed, Riadh; Mehta, Sunil; Figueredo, Aurelio José; Aldridge, Sarah; Balson, Hannah; Meyer, Caroline; Palmer, Robert

    2012-01-01

    The sexual competition hypothesis (SCH) contends that intense female intrasexual competition (ISC) is the ultimate cause of eating disorders. The SCH explains the phenomenon of the pursuit of thinness as an adaptation to ISC in the modern environment. It argues that eating disorders are pathological phenomena that arise from the mismatch between the modern environment and the inherited female adaptations for ISC. The present study has two aims. The first is to examine the relationship between disordered eating behavior (DEB) and ISC in a sample of female undergraduates. The second is to establish whether there is any relationship between disordered eating behavior and life history (LH) strategy. Participants completed a battery of questionnaires examining eating-related attitudes and behaviors, ISC, and LH strategy. A group of 206 female undergraduates were recruited. A structural equation model was constructed to analyze the data. ISC for mates was significantly associated with DEB, as predicted by the SCH. DEB was found to be predicted by fast LH strategy, which was only partially mediated by the SCH. The results of this study are supportive of the SCH and justify research on a clinical sample.

  14. Eating Disorders and Intrasexual Competition: Testing an Evolutionary Hypothesis among Young Women

    Directory of Open Access Journals (Sweden)

    Riadh Abed

    2012-01-01

    Full Text Available The sexual competition hypothesis (SCH contends that intense female intrasexual competition (ISC is the ultimate cause of eating disorders. The SCH explains the phenomenon of the pursuit of thinness as an adaptation to ISC in the modern environment. It argues that eating disorders are pathological phenomena that arise from the mismatch between the modern environment and the inherited female adaptations for ISC. The present study has two aims. The first is to examine the relationship between disordered eating behavior (DEB and ISC in a sample of female undergraduates. The second is to establish whether there is any relationship between disordered eating behavior and life history (LH strategy. Participants completed a battery of questionnaires examining eating-related attitudes and behaviors, ISC, and LH strategy. A group of 206 female undergraduates were recruited. A structural equation model was constructed to analyze the data. ISC for mates was significantly associated with DEB, as predicted by the SCH. DEB was found to be predicted by fast LH strategy, which was only partially mediated by the SCH. The results of this study are supportive of the SCH and justify research on a clinical sample.

  15. Testing the low-density hypothesis for reversed sex change in polygynous fish: experiments in Labroides dimidiatus.

    Science.gov (United States)

    Kuwamura, Tetsuo; Kadota, Tatsuru; Suzuki, Shohei

    2014-03-13

    Hermaphroditism is ubiquitous among plants and widespread in the animal kingdom. It is an unsolved problem why reversed sex change has evolved in polygynous and protogynous reef fish. We have previously suggested that facultative monogamy occurs in low-density populations of polygynous species and that males that become single as a result of accidental mate loss may change sex when they meet larger males. In this study, to test this 'low-density hypothesis', we conducted field experiments with the coral reef fish Labroides dimidiatus in which a portion of females were removed to create a low-density situation. The 'widowed' males moved to search for a new mate when no male, female or juvenile fish migrated into their territories and paired with nearby single fish, whether male or female. Alternatively, males expanded their territories to take over the nearest pair whose male was much smaller. These results support our low-density hypothesis.

  16. Human Values and Trust in Institutions across Countries: A Multilevel Test of Schwartz's Hypothesis of Structural Equivalence

    Directory of Open Access Journals (Sweden)

    Davide Morselli

    2012-04-01

    Full Text Available The goal of this article was to show how structural equation modelling associated to multilevel regressions represents a powerful tool to examine innovative cross-cultural research questions. The relationship between values and trust in institutions was investigated in four cross-cultural datasets: three were students and teacher samples; the last was a general sample from the 2005 World Values Survey (WVS. The hypothesis of equivalence of the structure of relations between values and trust in institutions (sinusoid curve hypothesis was tested with a series of multilevel multiple indicators and multiple causes models with random slopes. Structural equivalence was confirmed for student samples, but not for the general sample. The between-country variance of the relationship between values and trust in the general sample was partially explained by country level differences in socio-economic wealth and quality of governance.

  17. Testing the associative-link hypothesis in immediate serial recall: Evidence from word frequency and word imageability effects.

    Science.gov (United States)

    Tse, Chi-Shing; Altarriba, Jeanette

    2007-08-01

    Two immediate serial recall experiments were conducted to test the associative-link hypothesis (Stuart & Hulme, 2000). We manipulated interitem association by varying the intralist latent semantic analysis (LSA) cosines in our 7-item study word lists, each of which consists of high- or low-frequency words in Experiment 1 and high- or low-imageability words in Experiment 2. Whether item recall performance was scored by a serial-recall or free-recall criterion, we found main effects of interitem association, word imageability, and word frequency. The effect of interitem association also interacted with the word frequency effect, but not with the word imageability effect. The LSA-cosinexword frequency interaction occurred in the recency, but not primacy, portion of the serial position curve. The present findings set explanatory boundaries for the associative-link hypothesis and we argue that both item- and associative-based mechanisms are necessary to account for the word frequency effect in immediate serial recall.

  18. Testing the Hypothesis of Biofilm as a Source for Soft Tissue and Cell-Like Structures Preserved in Dinosaur Bone

    Science.gov (United States)

    2016-01-01

    Recovery of still-soft tissue structures, including blood vessels and osteocytes, from dinosaur bone after demineralization was reported in 2005 and in subsequent publications. Despite multiple lines of evidence supporting an endogenous source, it was proposed that these structures arose from contamination from biofilm-forming organisms. To test the hypothesis that soft tissue structures result from microbial invasion of the fossil bone, we used two different biofilm-forming microorganisms to inoculate modern bone fragments from which organic components had been removed. We show fundamental morphological, chemical and textural differences between the resultant biofilm structures and those derived from dinosaur bone. The data do not support the hypothesis that biofilm-forming microorganisms are the source of these structures. PMID:26926069

  19. Testing the Hypothesis of Biofilm as a Source for Soft Tissue and Cell-Like Structures Preserved in Dinosaur Bone.

    Science.gov (United States)

    Schweitzer, Mary Higby; Moyer, Alison E; Zheng, Wenxia

    2016-01-01

    Recovery of still-soft tissue structures, including blood vessels and osteocytes, from dinosaur bone after demineralization was reported in 2005 and in subsequent publications. Despite multiple lines of evidence supporting an endogenous source, it was proposed that these structures arose from contamination from biofilm-forming organisms. To test the hypothesis that soft tissue structures result from microbial invasion of the fossil bone, we used two different biofilm-forming microorganisms to inoculate modern bone fragments from which organic components had been removed. We show fundamental morphological, chemical and textural differences between the resultant biofilm structures and those derived from dinosaur bone. The data do not support the hypothesis that biofilm-forming microorganisms are the source of these structures.

  20. Testing the Hypothesis of Biofilm as a Source for Soft Tissue and Cell-Like Structures Preserved in Dinosaur Bone.

    Directory of Open Access Journals (Sweden)

    Mary Higby Schweitzer

    Full Text Available Recovery of still-soft tissue structures, including blood vessels and osteocytes, from dinosaur bone after demineralization was reported in 2005 and in subsequent publications. Despite multiple lines of evidence supporting an endogenous source, it was proposed that these structures arose from contamination from biofilm-forming organisms. To test the hypothesis that soft tissue structures result from microbial invasion of the fossil bone, we used two different biofilm-forming microorganisms to inoculate modern bone fragments from which organic components had been removed. We show fundamental morphological, chemical and textural differences between the resultant biofilm structures and those derived from dinosaur bone. The data do not support the hypothesis that biofilm-forming microorganisms are the source of these structures.

  1. Culture and fertility in the Nepal Himalayas: a test of a hypothesis.

    Science.gov (United States)

    Ross, J L

    1984-01-01

    In the Nepal Himalayas the Tibetan sociocultural system of fraternal polyandry (the form of marriage where 1 woman has 2 or more brothers as husbands) reduces aggregate fertility whereas Hindu marriage patterns appear to maximize fertility since there is very early and universally monogamous marriages. Over an 18-month period, reseach in the upper reaches of the Humla Distrist of northwestern Nepal focused upon 2 culturally distinct but geographically contiguous communities. 1 is Nepali speaking and high-caste Hindu; the other, Tibetan speaking and Buddhist. The 2 populations present a relatively unique natural laboratory in which several key factors (geographic, environmental and economic) are controlled. Population dynamics in these 2 communities are principally determined by patterns of fertility and mortality. A summary of a number of characteristics of the population dynamics of these 2 populations (e.g., age at 1st birth, birth interval, crude birth rate, completed fertility rate, general fertility rate, % children surviving), shows that they are more alike than dissimilar. Fertility levels between the Hindu and Tibetan population are virtually the same. While Tibetan fraternal polyandry does reduce aggregate fertility, the hypothesis that the Tibetans would have a substantially lower fertility rate than the Hindus is false, because the effects of fraternal polyandry are roughly balanced by the effects of post-widowhood celibacy among the Hindus. This study points up an important issue often overlooked in demographic analysis. Aggregate statistics such as the completed fertility rate, while important, can be deceptive, since very different factors can produce the same result at any given point in time. Diachronically, however, these underlying facotrs may change very differently. For example, fraternal poyandry is highly susceptiable to change because of the constant reevaluation of the opportunity costs associated with its practice. Anticipating the

  2. Fires in Seasonally Dry Tropical Forest: Testing the Varying Constraints Hypothesis across a Regional Rainfall Gradient.

    Science.gov (United States)

    Mondal, Nandita; Sukumar, Raman

    2016-01-01

    The "varying constraints hypothesis" of fire in natural ecosystems postulates that the extent of fire in an ecosystem would differ according to the relative contribution of fuel load and fuel moisture available, factors that vary globally along a spatial gradient of climatic conditions. We examined if the globally widespread seasonally dry tropical forests (SDTFs) can be placed as a single entity in this framework by analyzing environmental influences on fire extent in a structurally diverse SDTF landscape in the Western Ghats of southern India, representative of similar forests in monsoonal south and southeast Asia. We used logistic regression to model fire extent with factors that represent fuel load and fuel moisture at two levels-the overall landscape and within four defined moisture regimes (between 700 and1700 mm yr-1)-using a dataset of area burnt and seasonal rainfall from 1990 to 2010. The landscape scale model showed that the extent of fire in a given year within this SDTF is dependent on the combined interaction of seasonal rainfall and extent burnt the previous year. Within individual moisture regimes the relative contribution of these factors to the annual extent burnt varied-early dry season rainfall (i.e., fuel moisture) was the predominant factor in the wettest regime, while wet season rainfall (i.e., fuel load) had a large influence on fire extent in the driest regime. Thus, the diverse structural vegetation types associated with SDTFs across a wide range of rainfall regimes would have to be examined at finer regional or local scales to understand the specific environmental drivers of fire. Our results could be extended to investigating fire-climate relationships in STDFs of monsoonal Asia.

  3. Confidence bounds and hypothesis tests for normal distribution coefficients of variation

    Science.gov (United States)

    Steve Verrill; Richard A. Johnson

    2007-01-01

    For normally distributed populations, we obtain confidence bounds on a ratio of two coefficients of variation, provide a test for the equality of k coefficients of variation, and provide confidence bounds on a coefficient of variation shared by k populations.

  4. Multidimensional Computerized Adaptive Testing for Indonesia Junior High School Biology

    Science.gov (United States)

    Kuo, Bor-Chen; Daud, Muslem; Yang, Chih-Wei

    2015-01-01

    This paper describes a curriculum-based multidimensional computerized adaptive test that was developed for Indonesia junior high school Biology. In adherence to the Indonesian curriculum of different Biology dimensions, 300 items was constructed, and then tested to 2238 students. A multidimensional random coefficients multinomial logit model was…

  5. General Multidecision Theory: Hypothesis Testing and Changepoint Detection with Applications to Homeland Security

    Science.gov (United States)

    2016-01-19

    Paper for Special Issue in honor of the 80th birthday of Professor Albert Shiryaev) (05 2014) TOTAL: 2 Books Number of Manuscripts: Patents Submitted...Properties of the Multihypothesis Sequential Tests Consider the following problem of testing multiple composite hypotheses associated with gen- eral non-iid...case this is still an open problem . Remark 2. The assertions of Theorem 2 remain true if the normalization by n in (8) is replaced with the

  6. Nitrogen Exchanges: Testing the Hypothesis of a Country without Agricultural Production

    Directory of Open Access Journals (Sweden)

    M.-F. Slak

    2001-01-01

    Full Text Available Today, finding data on agricultural nitrogen balances is quite easy. Calculations of such balances are carried out by most of the European countries as an indicator of environmental pollution attributable to the agricultural sector. In France, average values of agricultural nitrogen balances show an excess of 1.5 to 2 million tons of nitrogen. This excess is enormous. What would the balance of a country be if agricultural activity were stopped? In the following article, a country (France is used as an example without agriculture is studied in order to assess its nitrogen balance. Using a previously published model describing nitrogen input and output of a given country, nitrogen flows are identified. Inputs include deposition, fixation, and products not intended for agricultural use. Outputs are reduced to zero if agriculture disappears (in France, agriculture is the only sector exporting products containing nitrogen. All flows are calculated considering the hypothesis of disappearance of agriculture. Nitrogen requirements to feed people and pets in France are estimated based on medical and veterinary data (recommended daily amounts for proteins and/or usual average consumption. Indeed, most of the food that nourishes the French population is produced nationally. If agriculture stops, it will be necessary to import food from foreign countries. Results show an unexpectedly high excess (for a country without agriculture having a structure similar to France: number of human beings and pets of 1.5 million tons of nitrogen. An attempt to calculate an agricultural balance with the same data gives a result close to 3 million tons. Differences in French agricultural balances found in the literature can mainly be explained by values taken into account for deposition and fixation (values used here are at least 300,000 tons higher than values used by the Organisation for Economic Co-operation and Development. In conclusion, nitrogen excess in agriculture

  7. "Paleoseismograms": Testing a Hypothesis of Source-Time Function Recording of Paleoearthquakes

    Science.gov (United States)

    Garrett, A.; Goldfinger, C.; Patton, J. R.; Morey, A. E.

    2011-12-01

    profiles of the deposits, reflecting considerable detail of the input source. We successfully simulated input perturbations of single and multiple input energy peaks of varying lengths and flow hydrographs, as well as simulated hyperpycnal flows, with consistent results across a wide range of timing and and parameter scaling variations. We conclude that turbidite records may record information about the triggering event. For earthquake sources, we suggest that a crude record of the source-time function of the earthquake may be recorded in the turbidite deposits. This hypothesis may explain the unusual correlation of isolated paleoseismic sites in Cascadia, the NSAF and Sumatra. If correct, turbidites under ideal conditions may record enough source information to be considered "paleoseismograms" recording information about paleo-rupture sequences on large fault systems. Data from turbidites found in land-locked inlets and sub-alpine Cascadia lakes are consistent with this experimental result

  8. Comparison of agriculture biology and general biology testing outcomes in Utah

    Science.gov (United States)

    Despain, Deric Walter

    Agriculture education can take scientific topics to higher levels, emphasize scientific concepts, involve hands-on learning, and develop interrelationships with the other sciences, thus making the living and non-living world around them relevant for students. Prior to 1996, agriculture education was not considered adequate to prepare Utah high school students to meet state biology requirements. The appropriateness of making that equalizing decision in 1996 was not tested until this 2014 study, comparing student test scores on the state biology test for general biology and agriculture biology students. The 2008-2012 data were collected from the Utah Department of Education Data and Statistics, utilizing a descriptive comparative post-test only analysis. As seen in this study, not only did B/AS students tend to score lower than their General Biology counterparts, in multiple cases this difference was significant (p ≤ .05). This contrary finding challenges the theoretical foundation of this study. As a result of this study three implications were made; (a) the Utah CRT-Biology test is not a reliable gauge of academic achievement in agriculture biology, (b) agriculture students in the sample population have not been taught with rigorous biology standards, and (c) biology standards taught in agricultural biology classes are not aligned with content tested by the biology portion of the Utah CRT-Biology test standards. The results of this study indicate to stakeholders that there is a gap occurring within the B/AS education, and the need to reevaluate the biology curriculum delivery to its population may possibly be in need of immediate action.

  9. God's punishment and public goods : A test of the supernatural punishment hypothesis in 186 world cultures.

    Science.gov (United States)

    Johnson, Dominic D P

    2005-12-01

    Cooperation towards public goods relies on credible threats of punishment to deter cheats. However, punishing is costly, so it remains unclear who incurred the costs of enforcement in our evolutionary past. Theoretical work suggests that human cooperation may be promoted if people believe in supernatural punishment for moral transgressions. This theory is supported by new work in cognitive psychology and by anecdotal ethnographic evidence, but formal quantitative tests remain to be done. Using data from 186 societies around the globe, I test whether the likelihood of supernatural punishment-indexed by the importance of moralizing "high gods"-is associated with cooperation.

  10. Testing the ‘residential rootedness’ hypothesis of self-employment for Germany and the UK

    NARCIS (Netherlands)

    Reuschke, D.; Van Ham, M.

    2013-01-01

    The work on this paper was funded by a Marie Curie grant from the European Commission within the 7th Framework Program (ID 252752). Based on the notion that entrepreneurship is a ‘local event’, the literature argues that entrepreneurs are ‘rooted’ in place. This paper tests the ‘residential

  11. Comparing Treatment and Control Groups on Multiple Outcomes: Robust Procedures for Testing a Directional Alternative Hypothesis

    Science.gov (United States)

    Lix, Lisa M.; Deering, Kathleen N.; Fouladi, Rachel T.; Manivong, Phongsack

    2009-01-01

    This study considers the problem of testing the difference between treatment and control groups on m [greater than or equal to] 2 measures when it is assumed a priori that the treatment group will perform better than the control group on all measures. Two procedures are investigated that do not rest on the assumptions of covariance homogeneity or…

  12. Perceptual Learning Style and Learning Proficiency: A Test of the Hypothesis

    Science.gov (United States)

    Kratzig, Gregory P.; Arbuthnott, Katherine D.

    2006-01-01

    Given the potential importance of using modality preference with instruction, the authors tested whether learning style preference correlated with memory performance in each of 3 sensory modalities: visual, auditory, and kinesthetic. In Study 1, participants completed objective measures of pictorial, auditory, and tactile learning and learning…

  13. Testing the strain hypothesis of the Demand Control Model to explain severe bullying at work

    NARCIS (Netherlands)

    Notelaers, G.; Baillien, E.; de Witte, H.; Einarsen, S.; Vermunt, J.K.

    2013-01-01

    Workplace bullying has often been attributed to work-related stress, and has been linked to the Job Demand Control Model. The current study aims to further these studies by testing the model for bullying in a heterogeneous sample and by using latent class (LC)-analyses to define different demands

  14. The P-Value Concept in Hypothesis Testing and Its Application on ...

    African Journals Online (AJOL)

    West African Journal of Industrial and Academic Research ... This study is aimed at comparing the probability value (p–value) of various hypotheses tested with the specified level of significance á at 5% level. ... The study finally recommends the use of p–value to take care of the probability of committing a type I error.

  15. Bibliographic Retrieval from Bibliographic Input; the Hypothesis and Construction of a Test

    Directory of Open Access Journals (Sweden)

    Frederick H. Ruecking, Jr.

    1968-12-01

    Full Text Available A study of problems associated with bibliographic retrieval using unverified input data supplied by requesters. A code derived from compression of title and author information to four, four-character abbreviations each was used for retrieval tests on an IBM 1401 computer. Retrieval accuracy was 98.67%

  16. Political identification and the defining issues test: reevaluating an old hypothesis.

    Science.gov (United States)

    Crowson, H Michael; DeBacker, Teresa K

    2008-02-01

    Research on the association between the development of moral judgment (as measured by the Defining Issues Test [DIT]; J. R. Rest, 1979) and political attitudes has demonstrated that these factors are often reliably related. N. Emler (1987, 1990) and colleagues have asserted that DIT scores actually measure test-takers' political identity rather than their developmental level. To test this claim, these researchers have designed "faking studies" in which respondents are asked to complete the DIT as if they were of a particular political orientation, regardless of their real political views. These faking studies have yielded contradictory conclusions, whereas tests of the incremental validity of the DIT have provided some evidence for its empirical distinctiveness. In the present study, the authors reexamined this issue by pitting scores on the DIT, Version 2 (DIT-2; J. R. Rest, D. Narvaez, S. J. Thoma, & M. J. Bebeau, 1999) against several more concrete measures of political identification in several predictive models of attitudes toward human rights and civil liberties. DIT-2 scores and political identification emerged as significant predictors in nearly all regression analyses.

  17. What's in a p? Reassessing best practices for conducting and reporting hypothesis-testing research

    NARCIS (Netherlands)

    Meyer, Klaus E.; Van Witteloostuijn, Arjen; Beugelsdijk, Sjoerd

    2017-01-01

    Social science research has recently been subject to considerable criticism regarding the validity and power of empirical tests published in leading journals, and business scholarship is no exception. Transparency and replicability of empirical findings are essential to build a cumulative body of

  18. Testing the Hypothesis of the Multidimensional Model of Anorexia Nervosa in Adolescents.

    Science.gov (United States)

    Lyon, Maureen; Chatoor, Irene; Atkins, Darlene; Silber, Tomas; Mosimann, James; Gray, James

    1997-01-01

    Tested six hypothesized risk factors of a model for anorexia nervosa. Results confirmed three of the risk factors: family history of depression, feelings of ineffectiveness, and poor interceptive awareness. Alcohol and drug abuse also figured prominently in the family history of patients with anorexia nervosa. (RJM)

  19. Testing the economic independence hypothesis: the effect of an exogenous increase in child support on subsequent marriage and cohabitation.

    Science.gov (United States)

    Cancian, Maria; Meyer, Daniel R

    2014-06-01

    We examine the effects of an increase in income on the cohabitation and marriage of single mothers. Using data from an experiment that resulted in randomly assigned differences in child support receipt for welfare-receiving single mothers, we find that exogenous income increases (as a result of receiving all child support that was paid) are associated with significantly lower cohabitation rates between mothers and men who are not the fathers of their child(ren). Overall, these results support the hypothesis that additional income increases disadvantaged women's economic independence by reducing the need to be in the least stable type of partnerships. Our results also show the potential importance of distinguishing between biological and social fathers.

  20. Testing the Developmental Origins of Health and Disease Hypothesis for Psychopathology Using Family-Based Quasi-Experimental Designs.

    Science.gov (United States)

    D'Onofrio, Brian M; Class, Quetzal A; Lahey, Benjamin B; Larsson, Henrik

    2014-09-01

    The Developmental Origin of Health and Disease (DOHaD) hypothesis is a broad theoretical framework that emphasizes how early risk factors have a causal influence on psychopathology. Researchers have raised concerns about the causal interpretation of statistical associations between early risk factors and later psychopathology because most existing studies have been unable to rule out the possibility of environmental and genetic confounding. In this paper we illustrate how family-based quasi-experimental designs can test the DOHaD hypothesis by ruling out alternative hypotheses. We review the logic underlying sibling-comparison, co-twin control, offspring of siblings/twins, adoption, and in vitro fertilization designs. We then present results from studies using these designs focused on broad indices of fetal development (low birth weight and gestational age) and a particular teratogen, smoking during pregnancy. The results provide mixed support for the DOHaD hypothesis for psychopathology, illustrating the critical need to use design features that rule out unmeasured confounding.

  1. Do the disadvantaged legitimize the social system? A large-scale test of the status-legitimacy hypothesis.

    Science.gov (United States)

    Brandt, Mark J

    2013-05-01

    System justification theory (SJT) posits that members of low-status groups are more likely to see their social systems as legitimate than members of high-status groups because members of low-status groups experience a sense of dissonance between system motivations and self/group motivations (Jost, Pelham, Sheldon, & Sullivan, 2003). The author examined the status-legitimacy hypothesis using data from 3 representative sets of data from the United States (American National Election Studies and General Social Surveys) and throughout the world (World Values Survey; total N across studies = 151,794). Multilevel models revealed that the average effect across years in the United States and countries throughout the world was most often directly contrary to the status-legitimacy hypothesis or was practically zero. In short, the status-legitimacy effect is not a robust phenomenon. Two theoretically relevant moderator variables (inequality and civil liberties) were also tested, revealing weak evidence, null evidence, or contrary evidence to the dissonance-inspired status-legitimacy hypothesis. In sum, the status-legitimacy effect is not robust and is unlikely to be the result of dissonance. These results are used to discuss future directions for research, the current state of SJT, and the interpretation of theoretically relevant but contrary and null results. PsycINFO Database Record (c) 2013 APA, all rights reserved

  2. Testing the junk-food hypothesis on marine birds: Effects of prey type on growth and development

    Science.gov (United States)

    Romano, Marc D.; Piatt, John F.; Roby, D.D.

    2006-01-01

    The junk-food hypothesis attributes declines in productivity of marine birds and mammals to changes in the species of prey they consume and corresponding differences in nutritional quality of those prey. To test this hypothesis nestling Black-legged Kittiwakes (Rissa tridactyla) and Tufted Puffins (Fratercula cirrhata) were raised in captivity under controlled conditions to determine whether the type and quality of fish consumed by young seabirds constrains their growth and development. Some nestlings were fed rations of Capelin (Mallotus villosus), Herring (Clupea pallasi) or Sand Lance (Ammodytes hexapterus) and their growth was compared with nestlings raised on equal biomass rations of Walleye Pollock (Theragra chalcograma). Nestlings fed rations of herring, sand lance, or capelin experienced higher growth increments than nestlings fed pollock. The energy density of forage fish fed to nestlings had a marked effect on growth increments and could be expected to have an effect on pre- and post-fledging survival of nestlings in the wild. These results provide empirical support for the junk-food hypothesis.

  3. ON ESTIMATION AND HYPOTHESIS TESTING OF THE GRAIN SIZE DISTRIBUTION BY THE SALTYKOV METHOD

    Directory of Open Access Journals (Sweden)

    Yuri Gulbin

    2011-05-01

    Full Text Available The paper considers the problem of validity of unfolding the grain size distribution with the back-substitution method. Due to the ill-conditioned nature of unfolding matrices, it is necessary to evaluate the accuracy and precision of parameter estimation and to verify the possibility of expected grain size distribution testing on the basis of intersection size histogram data. In order to review these questions, the computer modeling was used to compare size distributions obtained stereologically with those possessed by three-dimensional model aggregates of grains with a specified shape and random size. Results of simulations are reported and ways of improving the conventional stereological techniques are suggested. It is shown that new improvements in estimating and testing procedures enable grain size distributions to be unfolded more efficiently.

  4. Testing the Kerr black hole hypothesis: Comparison between the gravitational wave and the iron line approaches

    Directory of Open Access Journals (Sweden)

    Alejandro Cárdenas-Avendaño

    2016-09-01

    Full Text Available The recent announcement of the detection of gravitational waves by the LIGO/Virgo Collaboration has opened a new window to test the nature of astrophysical black holes. Konoplya & Zhidenko have shown how the LIGO data of GW 150914 can constrain possible deviations from the Kerr metric. In this letter, we compare their constraints with those that can be obtained from accreting black holes by fitting their X-ray reflection spectrum, the so-called iron line method. We simulate observations with eXTP, a next generation X-ray mission, finding constraints much stronger than those obtained by Konoplya & Zhidenko. Our results can at least show that, contrary to what is quite commonly believed, it is not obvious that gravitational waves are the most powerful approach to test strong gravity. In the presence of high quality data and with the systematics under control, the iron line method may provide competitive constraints.

  5. Testing the Kerr black hole hypothesis: Comparison between the gravitational wave and the iron line approaches

    Energy Technology Data Exchange (ETDEWEB)

    Cárdenas-Avendaño, Alejandro [Center for Field Theory and Particle Physics and Department of Physics, Fudan University, 200433 Shanghai (China); Programa de Matemática, Fundación Universitaria Konrad Lorenz, 110231 Bogotá (Colombia); Jiang, Jiachen [Center for Field Theory and Particle Physics and Department of Physics, Fudan University, 200433 Shanghai (China); Bambi, Cosimo, E-mail: bambi@fudan.edu.cn [Center for Field Theory and Particle Physics and Department of Physics, Fudan University, 200433 Shanghai (China); Theoretical Astrophysics, Eberhard-Karls Universität Tübingen, 72076 Tübingen (Germany)

    2016-09-10

    The recent announcement of the detection of gravitational waves by the LIGO/Virgo Collaboration has opened a new window to test the nature of astrophysical black holes. Konoplya & Zhidenko have shown how the LIGO data of GW 150914 can constrain possible deviations from the Kerr metric. In this letter, we compare their constraints with those that can be obtained from accreting black holes by fitting their X-ray reflection spectrum, the so-called iron line method. We simulate observations with eXTP, a next generation X-ray mission, finding constraints much stronger than those obtained by Konoplya & Zhidenko. Our results can at least show that, contrary to what is quite commonly believed, it is not obvious that gravitational waves are the most powerful approach to test strong gravity. In the presence of high quality data and with the systematics under control, the iron line method may provide competitive constraints.

  6. Shareholder Protection and Stock Market Development: An Empirical Test of the Legal Origins Hypothesis

    OpenAIRE

    John Armour; Simon Deakin; Prabirjit Sarkar; Mathias Siems; Ajit Singh

    2008-01-01

    We test the ‘law matters’ and ‘legal origin’claims using a newly created panel dataset measuring legal change over time in a sample of developed and developing countries. Our dataset improves on previous ones by avoiding country-specific variables in favour of functional and generic descriptors, by taking into account a wider range of legal data, and by considering the effects of weighting variables in different ways, thereby ensuring greater consistency of coding....

  7. Testing for Service-Led and Investment-Led Hypothesis: Evidence from ‘Chindia’

    OpenAIRE

    Baharom, A.H.; Habibullah, M.S.

    2008-01-01

    This study examines the meaningful relationship between economic growth, and service sector contribution and domestic investment in two major Asian economies, namely India and China. Autoregressive Distributed Lag (ARDL) bounds testing procedure is employed to analyze the impact of the selected variables namely (1) contribution by the service sector, (2) (4) domestic investment on economic growth and vice versa. The period of interest is 1960-2005 using annual data. The empirical results demo...

  8. Active SAmpling Protocol (ASAP) to Optimize Individual Neurocognitive Hypothesis Testing: A BCI-Inspired Dynamic Experimental Design.

    Science.gov (United States)

    Sanchez, Gaëtan; Lecaignard, Françoise; Otman, Anatole; Maby, Emmanuel; Mattout, Jérémie

    2016-01-01

    The relatively young field of Brain-Computer Interfaces has promoted the use of electrophysiology and neuroimaging in real-time. In the meantime, cognitive neuroscience studies, which make extensive use of functional exploration techniques, have evolved toward model-based experiments and fine hypothesis testing protocols. Although these two developments are mostly unrelated, we argue that, brought together, they may trigger an important shift in the way experimental paradigms are being designed, which should prove fruitful to both endeavors. This change simply consists in using real-time neuroimaging in order to optimize advanced neurocognitive hypothesis testing. We refer to this new approach as the instantiation of an Active SAmpling Protocol (ASAP). As opposed to classical (static) experimental protocols, ASAP implements online model comparison, enabling the optimization of design parameters (e.g., stimuli) during the course of data acquisition. This follows the well-known principle of sequential hypothesis testing. What is radically new, however, is our ability to perform online processing of the huge amount of complex data that brain imaging techniques provide. This is all the more relevant at a time when physiological and psychological processes are beginning to be approached using more realistic, generative models which may be difficult to tease apart empirically. Based upon Bayesian inference, ASAP proposes a generic and principled way to optimize experimental design adaptively. In this perspective paper, we summarize the main steps in ASAP. Using synthetic data we illustrate its superiority in selecting the right perceptual model compared to a classical design. Finally, we briefly discuss its future potential for basic and clinical neuroscience as well as some remaining challenges.

  9. Molecular phylogeny of selected species of the order Dinophysiales (Dinophyceae) - testing the hypothesis of a Dinophysioid radiation

    DEFF Research Database (Denmark)

    Jensen, Maria Hastrup; Daugbjerg, Niels

    2009-01-01

    additional information on morphology and ecology to these evolutionary lineages. We have for the first time combined morphological information with molecular phylogenies to test the dinophysioid radiation hypothesis in a modern context. Nuclear-encoded LSU rDNA sequences including domains D1-D6 from 27....... The phylogenetic trees furthermore revealed convergent evolution of several morphological characters in the dinophysioids. According to the molecular data, the dinophysioids appeared to have evolved quite differently from the radiation schemes previously hypothesized. Four dinophysioid species had identical LSU r...

  10. Statistical test of a null hypothesis: Taser shocks have not caused or contributed to subsequent in-custody deaths

    Science.gov (United States)

    Lundquist, Marjorie

    2009-03-01

    Since 1999 over 425 in-custody deaths have occurred in the USA after law enforcement officers (LEOs) used an M26 or X26 Taser, causing Amnesty International and the ACLU to call for a moratorium on Taser use until its physiological effects on people have been better studied. A person's Taser dose is defined as the total duration (in seconds) of all Taser shocks received by that person during a given incident. Utilizing the concept of Taser dose for these deaths, TASER International's claim of Taser safety can be treated as a null hypothesis and its validity scientifically tested. Such a test using chi-square as the test statistic is presented. It shows that the null hypothesis should be rejected; i.e., model M26 and X26 Tasers are capable of producing lethal effects non-electrically and so have played a causal or contributory role in a great many of the in-custody deaths following their use. This implies that the Taser is a lethal weapon, and that LEOs have not been adequately trained in its safe use!

  11. Hypothesis test of mediation effect in causal mediation model with high-dimensional continuous mediators.

    Science.gov (United States)

    Huang, Yen-Tsung; Pan, Wen-Chi

    2016-06-01

    Causal mediation modeling has become a popular approach for studying the effect of an exposure on an outcome through a mediator. However, current methods are not applicable to the setting with a large number of mediators. We propose a testing procedure for mediation effects of high-dimensional continuous mediators. We characterize the marginal mediation effect, the multivariate component-wise mediation effects, and the L2 norm of the component-wise effects, and develop a Monte-Carlo procedure for evaluating their statistical significance. To accommodate the setting with a large number of mediators and a small sample size, we further propose a transformation model using the spectral decomposition. Under the transformation model, mediation effects can be estimated using a series of regression models with a univariate transformed mediator, and examined by our proposed testing procedure. Extensive simulation studies are conducted to assess the performance of our methods for continuous and dichotomous outcomes. We apply the methods to analyze genomic data investigating the effect of microRNA miR-223 on a dichotomous survival status of patients with glioblastoma multiforme (GBM). We identify nine gene ontology sets with expression values that significantly mediate the effect of miR-223 on GBM survival. © 2015, The International Biometric Society.

  12. Revisiting Parole Decision Making: Testing for the Punitive Hypothesis in a Large U.S. Jurisdiction.

    Science.gov (United States)

    Vîlcică, E Rely

    2018-04-01

    The decision to grant conditional release from prison (aka the parole decision) has been largely neglected in the contemporary criminological literature, despite its critical implications. The current study, conducted in Pennsylvania, United States, tests for punitive themes in parole decision making by examining the impact of several measures reflective of punishment satisfaction on the decision to grant release to eligible parole candidates. The results indicate that the amount of time served in relation to the original punishment does not predict parole decisions but the nature of the original offense does. Moreover, inmates eligible for parole have to experience at least one parole denial to increase their chances of release, suggesting that parole decision makers use the parole process as a punitive means. The implications of the findings are discussed.

  13. Motivation towards extracurricular activities and motivation at school: A test of the generalization effect hypothesis.

    Science.gov (United States)

    Denault, Anne-Sophie; Guay, Frédéric

    2017-01-01

    Participation in extracurricular activities is a promising avenue for enhancing students' school motivation. Using self-determination theory (Deci & Ryan, 2000), the goal of this study was to test a serial multiple mediator model. In this model, students' perceptions of autonomy support from their extracurricular activity leader predicted their activity-based intrinsic and identified regulations. In turn, these regulations predicted their school-based intrinsic and identified regulations during the same school year. Finally, these regulations predicted their school-based intrinsic and identified regulations one year later. A total of 276 youths (54% girls) from disadvantaged neighborhoods were surveyed over two waves of data collection. The proposed mediation model was supported for both types of regulation. These results highlight the generalization effects of motivation from the extracurricular activity context to the school context. Copyright © 2016 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

  14. Singular Spectrum Analysis for Astronomical Time Series: Constructing a Parsimonious Hypothesis Test

    Science.gov (United States)

    Greco, G.; Kondrashov, D.; Kobayashi, S.; Ghil, M.; Branchesi, M.; Guidorzi, C.; Stratta, G.; Ciszak, M.; Marino, F.; Ortolan, A.

    We present a data-adaptive spectral method - Monte Carlo Singular Spectrum Analysis (MC-SSA) - and its modification to tackle astrophysical problems. Through numerical simulations we show the ability of the MC-SSA in dealing with 1/f β power-law noise affected by photon counting statistics. Such noise process is simulated by a first-order autoregressive, AR(1) process corrupted by intrinsic Poisson noise. In doing so, we statistically estimate a basic stochastic variation of the source and the corresponding fluctuations due to the quantum nature of light. In addition, MC-SSA test retains its effectiveness even when a significant percentage of the signal falls below a certain level of detection, e.g., caused by the instrument sensitivity. The parsimonious approach presented here may be broadly applied, from the search for extrasolar planets to the extraction of low-intensity coherent phenomena probably hidden in high energy transients.

  15. Methods and baseline cardiovascular data from the Early versus Late Intervention Trial with Estradiol testing the menopausal hormone timing hypothesis.

    Science.gov (United States)

    Hodis, Howard N; Mack, Wendy J; Shoupe, Donna; Azen, Stanley P; Stanczyk, Frank Z; Hwang-Levine, Juliana; Budoff, Matthew J; Henderson, Victor W

    2015-04-01

    This study aims to present methods and baseline data from the Early versus Late Intervention Trial with Estradiol (ELITE), the only clinical trial designed to specifically test the timing hypothesis of postmenopausal hormone therapy (HT). The timing hypothesis posits that HT effects depend on the temporal initiation of HT relative to time since menopause. ELITE is a randomized, double-blind, placebo-controlled trial with a 2 × 2 factorial design. Six hundred forty-three healthy postmenopausal women without cardiovascular disease were randomized to oral estradiol or placebo for up to 6 to 7 years according to time since menopause (y). Carotid artery intima-media thickness (CIMT) and cardiac computed tomography were conducted to determine HT effects on subclinical atherosclerosis across menopause strata. Participants in the early and late postmenopausal strata were well-separated by mean age (55.4 vs 65.4 y) and median time since menopause (3.5 vs 14.3 y). Expected risk factors (age, blood pressure, and body mass index) were associated with CIMT at baseline in both strata. In the early postmenopausal group, but not in the late postmenopausal group, we observed significant associations between CIMT and factors that may play a role in the responsiveness of atherosclerosis progression according to timing of HT initiation. These include low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, sex hormone-binding globulin, and serum total estradiol. The ELITE randomized controlled trial is timely and unique. Baseline data indicate that ELITE is well-positioned to test the HT timing hypothesis in relation to atherosclerosis progression and coronary artery disease.

  16. Expertise in cognitive psychology: testing the hypothesis of long-term working memory in a study of soccer players.

    Science.gov (United States)

    Postal, Virginie

    2004-10-01

    This experiment compared several theories of expertise and exceptional performances in cognitive psychology. One current conception assumes that experts in a specific domain have developed a long-term working memory, which accounts for the difference in memory performance between experts and novices. The principal characteristics of this memory are the speed with which processes of storage and retrieval function and the existence of retrieval structures that allow a temporary activation of the knowledge store in long-term memory. Other authors such as Vicente and Wang argue this notion does not account for memory performance that is not intrinsic to the domain of expertise. We attempt to clarify the two viewpoints and to focus on this debate by testing the hypothesis of long-term working memory using soccer as the domain of expertise and by comparing the cognitive performance of participants who have different expertise (novices, supporters, players, and coaches). 35 male participants were administered a new version of the Reading Span test to assess their long-term working memory according to two conditions. In the first condition (structured condition), the last word of each sentence was related to the soccer domain, and these words were related to each other in such a manner that they represented a part of the game. In the second condition (unstructured condition), the last word of each sentence was related to soccer but these words did not represent part of the game. Analysis showed that the sentence span increased as a function of expertise for the structured condition but not for the unstructured condition. The results were interpreted in the framework of the constraint attunement hypothesis proposed by Vicente in 1992 and the long-term working memory hypothesis proposed by Ericsson and Kintsch in 1995.

  17. Assessing temporal variations in diversification rates from phylogenies: estimation and hypothesis testing

    Science.gov (United States)

    Paradis, E.

    1997-01-01

    A new method to estimate the diversification rate of a lineage from a phylogeny of recent species is presented. This uses survival models to analyse the ages of the species as derived from the phylogeny. Survival models can analyse missing data where the exact date of death is unknown (censoring). This approach allows us to include missing data (species not included in a detailed phylogenetic study) in the analysis, provided a minimum age is known for these species. Three models are presented, with emphasis on temporal variation in diversification rates. The maximum likelihood method and Akaike information criteria are used to derive estimators and tests of hypotheses. A simulation study demonstrates that the method is able to detect a temporal variation in diversification rate only when it is present, avoiding type I and type II errors. A lineage with ten species may be sufficient to detect a temporal variation in diversification rate even with 50 per cent of missing data. An application is presented with data from a phylogeny of birds of the genus Ramphocelus.

  18. Testing the transport energy-environmental Kuznets curve hypothesis in the EU27 countries

    International Nuclear Information System (INIS)

    Pablo-Romero, M.P.; Cruz, L.; Barata, E.

    2017-01-01

    Transport activities are essential for economic and social development. Nevertheless, the transport sector has also shown the fastest growth in energy consumption in the European Union and its contribution to increasing greenhouse gas emissions merits the thorough attention of academics and policy makers. In this paper we analyze the relationship of economic growth and transport activities with transport final energy consumption. Energy Kuznets curves are estimated for a panel data set covering the EU27 countries in the period 1995–2009 for total transport energy use, household transport energy use, and productive transport energy use (all three in absolute and per capita energy use terms). The productive transport energy use and gross value added relationship are further considered as per hour worked. Finally, the control variables of energy prices and differences in the economic structures are tested. Empirical results show that the elasticity of transport energy use with respect to gross value added in per capita terms decreases from a threshold for the three transport energy consumption variables, but the turning point of improved environmental quality is not reached in any instance. - Highlights: • Transport EKCs are estimated for the EU countries in the 1995–2009 period. • Total, household and production activity transport energy uses are analyzed. • Data support a concave shape, but the turning point is not reached. • Richer countries have more limited potential for energy efficiency policies. • EKCs elasticity values are considered to support policy interpretations.

  19. Exchange and cohesion in dyads and triads: A test of Simmel's hypothesis.

    Science.gov (United States)

    Yoon, Jeongkoo; Thye, Shane R; Lawler, Edward J

    2013-11-01

    This paper uses social exchange theory to address a classic question posed by Simmel (1964) regarding dyads and triads. The question is whether exchanges in a triad will generate more cohesion at the group level than exchanges in an isolated dyad. The main hypotheses, integrating several ideas from Simmel and social exchange theories, are as follows. First, triads generate less variability of behavior than dyads; that is, there is more uniformity or convergence in triads. Second, in the context of repeated exchange, we predict higher levels of cohesion in triads than in dyads. Third, positive emotion or affect has a stronger impact on cohesion in dyads than in triads, whereas uncertainty reduction has a stronger impact on cohesion in triads. To test these hypotheses, an experiment compared isolated dyads to dyads nested in a triadic exchange network. Subjects engaged in exchanges across a series of distinct episodes, using standard experimental procedures from research on relational cohesion (Lawler and Yoon, 1996) and exchange networks (Molm and Cook, 1995; Willer, 1999). Consistent with the hypotheses, the results reveal more convergence of behavior and higher cohesion in triads than in dyads; moreover, uncertainty reduction is the primary basis for cohesion in the triad, whereas positive affect was the primary basis for cohesion in the dyad. These results are discussed in relation to Simmelian dyad-triad dynamics and the theory of relational cohesion. Copyright © 2013 Elsevier Inc. All rights reserved.

  20. Experimental test of the viscous anisotropy hypothesis for partially molten rocks.

    Science.gov (United States)

    Qi, Chao; Kohlstedt, David L; Katz, Richard F; Takei, Yasuko

    2015-10-13

    Chemical differentiation of rocky planets occurs by melt segregation away from the region of melting. The mechanics of this process, however, are complex and incompletely understood. In partially molten rocks undergoing shear deformation, melt pockets between grains align coherently in the stress field; it has been hypothesized that this anisotropy in microstructure creates an anisotropy in the viscosity of the aggregate. With the inclusion of anisotropic viscosity, continuum, two-phase-flow models reproduce the emergence and angle of melt-enriched bands that form in laboratory experiments. In the same theoretical context, these models also predict sample-scale melt migration due to a gradient in shear stress. Under torsional deformation, melt is expected to segregate radially inward. Here we present torsional deformation experiments on partially molten rocks that test this prediction. Microstructural analyses of the distribution of melt and solid reveal a radial gradient in melt fraction, with more melt toward the center of the cylinder. The extent of this radial melt segregation grows with progressive strain, consistent with theory. The agreement between theoretical prediction and experimental observation provides a validation of this theory.

  1. Testing the interdependence hypothesis among native adult bilingual Russian-English students.

    Science.gov (United States)

    Abu-Rabia, S

    2001-07-01

    English and Russian are two different orthographies, the former being an opaque orthography, the latter being considered a direct letter-sound language. This study investigated the relationship between reading, syntactic, orthographic, and working memory skills in the two orthographies. Participants were first-year BA students of English (age range 25-30) at the University of Haifa who had completed high school in Russia. They were tested individually, in Russian and English, on working memory, spelling, oral cloze, visual condition, phonological condition, orthographic skills, word attack, and word identification. The results indicated positive significant correlations within and across languages, except for the orthographic skills and some of the correlations of the visual skills. The orthographic skills correlated highly significantly within each language but not across languages. Almost all the other linguistic skills correlated significantly within and across languages. Multiple regression procedures revealed that phonological and spelling skills in Russian, the first language, were strong predictors of word identification in English, the second language. These results are discussed in light of the interdependence and the script-dependent hypotheses.

  2. Testing the Kerr Black Hole Hypothesis Using X-Ray Reflection Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bambi, Cosimo; Nampalliwar, Sourabh [Center for Field Theory and Particle Physics and Department of Physics, Fudan University, 200433 Shanghai (China); Cárdenas-Avendaño, Alejandro [Programa de Matemática, Fundación Universitaria Konrad Lorenz, 110231 Bogotá (Colombia); Dauser, Thomas [Remeis Observatory and ECAP, Universität Erlangen-Nürnberg, D-96049 Bamberg (Germany); García, Javier A., E-mail: bambi@fudan.edu.cn [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

    2017-06-20

    We present the first X-ray reflection model for testing the assumption that the metric of astrophysical black holes is described by the Kerr solution. We employ the formalism of the transfer function proposed by Cunningham. The calculations of the reflection spectrum of a thin accretion disk are split into two parts: the calculation of the transfer function and the calculation of the local spectrum at any emission point in the disk. The transfer function only depends on the background metric and takes into account all the relativistic effects (gravitational redshift, Doppler boosting, and light bending). Our code computes the transfer function for a spacetime described by the Johannsen metric and can easily be extended to any stationary, axisymmetric, and asymptotically flat spacetime. Transfer functions and single line shapes in the Kerr metric are compared to those calculated from existing codes to check that we reach the necessary accuracy. We also simulate some observations with NuSTAR and LAD/eXTP and fit the data with our new model to show the potential capabilities of current and future observations to constrain possible deviations from the Kerr metric.

  3. Testing the mate-choice hypothesis of the female orgasm: disentangling traits and behaviours

    Directory of Open Access Journals (Sweden)

    James M. Sherlock

    2016-10-01

    Full Text Available Background: The evolution of the female orgasm in humans and its role in romantic relationships is poorly understood. Whereas the male orgasm is inherently linked to reproduction, the female orgasm is not linked to obvious reproductive or survival benefits. It also occurs less consistently during penetrative sex than does the male orgasm. Mate-choice hypotheses posit that the wide variation in female orgasm frequency reflects a discriminatory mechanism designed to select high-quality mates. Objective: We aimed to determine (1 whether women report that their orgasm frequency varies between partners, (2 whether this variation reflects mates' personal characteristics, and (3 whether this variation reflects own and partner sexual behaviour during intercourse. Design: We collected survey data from 103 women who rated (1 the extent to which their orgasm frequency varied between partners, (2 the characteristics of previous sexual partners who induced high-orgasm frequency and those who induced low-orgasm frequency, and (3 the specific behaviours during sex with those partners. This is the first study to test within-woman variation in orgasm and partner traits. Results: Overall, women reported variation in their orgasm rates with different partners. Partners who induced high-orgasm rates were rated as more humorous, creative, warm, faithful, and better smelling than partners who induced low-orgasm rates, and also engaged in greater efforts to induce partner orgasm. Conclusions: Some assumptions and predictions of mate-choice hypotheses of female orgasm were supported, while other aspects of our findings provide reasons to remain sceptical.

  4. Testing the "Sexually Abused-Abuser Hypothesis" in Adolescents: A Population-Based Study.

    Science.gov (United States)

    Aebi, Marcel; Landolt, Markus A; Mueller-Pfeiffer, Christoph; Schnyder, Ulrich; Maier, Thomas; Mohler-Kuo, Meichun

    2015-11-01

    A long-standing belief in the literature on sex offenders is that sexually victimized youths are at increased risk of becoming sex offenders themselves. The present study tested the link between past sexual abuse, either with or without contact, and sexually offending behavior in a representative sample of male and female adolescents while controlling for other types of abuse, mental health problems, substance use, and non-sexual violent behaviors. Self-reported data were collected from a nationally representative sample of 6,628 students attending 9th grade public school in Switzerland (3,434 males, 3,194 females, mean age = 15.50 years, SD = 0.66 years). Exposure to contact and non-contact types of sexual abuse was assessed using the Child Sexual Abuse Questionnaire and sexually offending behavior by the presence of any of three behaviors indicating sexual coercion. Two-hundred-forty-five males (7.1 %) and 40 females (1.2 %) reported having sexually coerced another person. After controlling for non-sexual abuse, low parent education, urban versus rural living, mental health problems, substance use, and non-sexual violent behavior, male adolescents who were victims of contact sexual abuse and non-contact sexual abuse were significantly more likely to report coercive sexual behaviors. Females who experienced contact or non-contact sexual abuse were also found at increased risk of committing sexual coercion after controlling for covariates. The present findings demonstrate a strong relationship between past sexual abuse, with and without physical contact, and sexual-offending behavior in male and female adolescents. Reducing exposure to non-contact sexual abuse (like Internet-based sexual exploitation) should become a new area of sexual violence prevention in youths.

  5. The Avalanche Hypothesis and Compression of Morbidity: Testing Assumptions through Cohort-Sequential Analysis.

    Directory of Open Access Journals (Sweden)

    Jordan Silberman

    Full Text Available The compression of morbidity model posits a breakpoint in the adult lifespan that separates an initial period of relative health from a subsequent period of ever increasing morbidity. Researchers often assume that such a breakpoint exists; however, this assumption is hitherto untested.To test the assumption that a breakpoint exists--which we term a morbidity tipping point--separating a period of relative health from a subsequent deterioration in health status. An analogous tipping point for healthcare costs was also investigated.Four years of adults' (N = 55,550 morbidity and costs data were retrospectively analyzed. Data were collected in Pittsburgh, PA between 2006 and 2009; analyses were performed in Rochester, NY and Ann Arbor, MI in 2012 and 2013. Cohort-sequential and hockey stick regression models were used to characterize long-term trajectories and tipping points, respectively, for both morbidity and costs.Morbidity increased exponentially with age (P<.001. A morbidity tipping point was observed at age 45.5 (95% CI, 41.3-49.7. An exponential trajectory was also observed for costs (P<.001, with a costs tipping point occurring at age 39.5 (95% CI, 32.4-46.6. Following their respective tipping points, both morbidity and costs increased substantially (Ps<.001.Findings support the existence of a morbidity tipping point, confirming an important but untested assumption. This tipping point, however, may occur earlier in the lifespan than is widely assumed. An "avalanche of morbidity" occurred after the morbidity tipping point-an ever increasing rate of morbidity progression. For costs, an analogous tipping point and "avalanche" were observed. The time point at which costs began to increase substantially occurred approximately 6 years before health status began to deteriorate.

  6. Daily life stress and the cortisol awakening response: testing the anticipation hypothesis.

    Directory of Open Access Journals (Sweden)

    Daniel J Powell

    Full Text Available The cortisol awakening response (CAR is a distinct facet of the circadian cortisol rhythm associated with various health conditions and risk factors. It has repeatedly been suggested that the CAR could be a result of the anticipated demands of the upcoming day (stress anticipation and could support coping with daily life stress. In a sample of 23 healthy participants CARs were assessed on two consecutive days by measures of salivary cortisol upon awakening (S1 and 30 and 45 minutes later, which were aggregated to the area under the curve increase (AUCI. Stress anticipation was assessed immediately after awakening. On the same days, daily life stress and distress were assessed six times per day based on a quasi-randomized design using handheld computers. Associations were tested by day using regression analysis and standard multilevel/mixed effects models for longitudinal data. The CAR AUCI moderated the effect of daily life stress on distress; higher CAR increases were associated with attenuated distress responses to daily life stress on both days (day 1: p = .039; day 2: p = .004 adjusted for age, gender, sleep quality, time of awakening and oral contraceptive use. Lagged-effects and redundancy models showed that this effect was not due to prior-day CAR increases but specific for same day CARs. On day 2, associations between daily life stress and distress were stronger when individuals showed a higher S1 cortisol level, but this effect was similar for S1 on day 1, and the day 2 effect of S1 became non-significant when S1 on day 1 was controlled. No associations were found between stress anticipation and CARs. Findings indicate that the CAR increase is associated with successful coping with same-day daily life stress.

  7. Testing the Nunatak Refugia Hypothesis in the Eastern Canadian Arctic with Cosmogenic Nuclides 14C, 10Be, and 26Al

    Science.gov (United States)

    Miller, G. H.; Briner, J. P.; Lifton, N.; Kaplan, M. R.; Refsnider, K. A.

    2008-12-01

    For more than a century the processes by which plants rapidly colonized vast regions formerly covered by Late Quaternary continental ice sheets has been vigorously debated. It has been postulated that refugial plant communities survived on nunataks above ice-sheet surfaces, and that these relict populations facilitated rapid colonization. While glacial mapping confirms that some highlands in the Eastern Canadian Arctic remained above the Laurentide Ice Sheet (LIS) throughout the last glacial maximum (LGM), whether they remained free of local ice carapaces is uncertain. To test the nunatak refugia hypothesis we sampled quartz-rich bedrock from rolling uplands of Broughton Is. (67.5 N; 63.5 E; 600 m asl), one of the most distal high islands bordering the eastern margin of the LIS. At the peak of the LGM, outlet glaciers of the LIS impinged on the island, but did not reach above 100 m asl. Close to the summit, flat-lying quartz-rich veins crop out extensively with 2 to 10 cm of weathering relief. Two samples have 10Be and 26Al exposure ages in excess of 200 ka, but 26Al/10Be of only 3.8. Two tors 150 m lower have 10Be and 26Al exposure ages in excess of 100 ka, and similarly low 26Al/10Be (3.5). The time elapsed to acquire these values exceeds 1 Ma without erosion for the higher samples, and only slightly less for the lower samples, confirming that these sites have not been inundated by actively eroding continental ice since at least the early Quaternary. To evaluate whether a protective ice cap mantled the island during the LGM we measured in situ 14C inventories in the two summit samples for which 10Be and 26Al were also measured. If the summit had been free of ice during the LGM and served as a plant refugium, then the 14C inventories should be at their maximum levels. If, however, the summit was mantled by a thick (>30 m) snowfield or cold-based ice carapace, then 14C inventories should reflect only Holocene surface exposure. Both samples contained in situ 14C

  8. Systems Cancer Biology and the Controlling Mechanisms for the J-Shaped Cancer Dose Response: Towards Relaxing the LNT Hypothesis.

    Science.gov (United States)

    Lou, In Chio; Zhao, Yuchao; Wu, Yingjie; Ricci, Paolo F

    2012-01-01

    The hormesis phenomena or J-shaped dose response have been accepted as a common phenomenon regardless of the involved biological model, endpoint measured and chemical class/physical stressor. This paper first introduced a mathematical dose response model based on systems biology approach. It links molecular-level cell cycle checkpoint control information to clonal growth cancer model to predict the possible shapes of the dose response curves of Ionizing Radiation (IR) induced tumor transformation frequency. J-shaped dose response curves have been captured with consideration of cell cycle checkpoint control mechanisms. The simulation results indicate the shape of the dose response curve relates to the behavior of the saddle-node points of the model in the bifurcation diagram. A simplified version of the model in previous work of the authors was used mathematically to analyze behaviors relating to the saddle-node points for the J-shaped dose response curve. It indicates that low-linear energy transfer (LET) is more likely to have a J-shaped dose response curve. This result emphasizes the significance of systems biology approach, which encourages collaboration of multidiscipline of biologists, toxicologists and mathematicians, to illustrate complex cancer-related events, and confirm the biphasic dose-response at low doses.

  9. Testing the stress-gradient hypothesis during the restoration of tropical degraded land using the shrub Rhodomyrtus tomentosa as a nurse plant

    Science.gov (United States)

    Nan Liu; Hai Ren; Sufen Yuan; Qinfeng Guo; Long Yang

    2013-01-01

    The relative importance of facilitation and competition between pairwise plants across abiotic stress gradients as predicted by the stress-gradient hypothesis has been confirmed in arid and temperate ecosystems, but the hypothesis has rarely been tested in tropical systems, particularly across nutrient gradients. The current research examines the interactions between a...

  10. In vitro strain in human metacarpal bones during striking: testing the pugilism hypothesis of hominin hand evolution.

    Science.gov (United States)

    Horns, Joshua; Jung, Rebekah; Carrier, David R

    2015-10-01

    The hands of hominins (i.e. bipedal apes) are distinguished by skeletal proportions that are known to enhance manual dexterity but also allow the formation of a clenched fist. Because male-male physical competition is important in the mating systems of most species of great apes, including humans, we tested the hypothesis that a clenched fist protects the metacarpal bones from injury by reducing the level of strain during striking. We used cadaver arms to measure in vitro strain in metacarpals during forward strikes with buttressed and unbuttressed fist postures and during side slaps with an open palm. If the protective buttressing hypothesis is correct, the clenched fist posture should substantially reduce strain in the metacarpal bones during striking and therefore reduce the risk of fracture. Recorded strains were significantly higher in strikes in which the hand was secured in unbuttressed and slapping postures than in the fully buttressed posture. Our results suggest that humans can safely strike with 55% more force with a fully buttressed fist than with an unbuttressed fist and with twofold more force with a buttressed fist than with an open-hand slap. Thus, the evolutionary significance of the proportions of the hominin hand may be that these are the proportions that improved manual dexterity while at the same time making it possible for the hand to be used as a club during fighting. © 2015. Published by The Company of Biologists Ltd.

  11. The origin of Phobos grooves from ejecta launched from impact craters on Mars: Tests of the hypothesis

    Science.gov (United States)

    Ramsley, Kenneth R.; Head, James W.

    2013-01-01

    The surface of the martian moon Phobos is characterized by parallel and intersecting grooves that bear resemblance to secondary crater chains observed on planetary surfaces. Murray (2011) has hypothesized that the main groove-forming process on Phobos is the intersection of Phobos with ejecta from primary impact events on Mars to produce chains of secondary craters. The hypothesis infers a pattern of parallel jets of ejecta, either fluidized or solidified, that break into equally-spaced fragments and disperse uniformly along-trajectory during the flight from Mars to Phobos. At the moment of impact with Phobos the dispersed fragments emplace secondary craters that are aligned along strike corresponding to the flight pattern of ejecta along trajectory. The aspects of the characteristics of grooves on Phobos cited by this hypothesis that might be explained by secondary ejecta include: their observed linearity, parallelism, planar alignment, pitted nature, change in character along strike, and a "zone of avoidance" where ejecta from Mars is predicted not to impact (Murray, 2011). To test the hypothesis we plot precise Keplerian orbits for ejecta from Mars (elliptical and hyperbolic with periapsis located below the surface of Mars). From these trajectories we: (1) set the fragment dispersion limits of ejecta patterns required to emplace the more typically well-organized parallel grooves observed in returned images from Phobos; (2) plot ranges of the ejecta flight durations from Mars to Phobos and map regions of exposure; (3) utilize the same exposure map to observe trajectory-defined ejecta exposure shadows; (4) observe hemispheric exposure in response to shorter and longer durations of ejecta flight; (5) assess the viability of ejecta emplacing the large family of grooves covering most of the northern hemisphere of Phobos; and (6) plot the arrival of parallel lines of ejecta emplacing chains of craters at oblique incident angles. We also assess the bulk volume of

  12. Test of Science Process Skills of Biology Students towards Developing of Learning Exercises

    Directory of Open Access Journals (Sweden)

    Judith S. Rabacal

    2016-11-01

    Full Text Available This is a descriptive study aimed to determine the academic achievement on science process skills of the BS Biology Students of Northern Negros State College of Science and Technology, Philippines with the end view of developing learning exercises which will enhance their academic achievement on basic and integrated science process skills. The data in this study were obtained using a validated questionnaire. Mean was the statistical tool used to determine the academic achievement on the above mentioned science process skills; t-test for independent means was used to determine significant difference on the academic achievement of science process skills of BS Biology students while Pearson Product Moment of Correlation Coefficient was used to determine the significant relationship between basic and integrated science process skills of the BS Biology students. A 0.05 level of significance was used to determine whether the hypothesis set in the study will be rejected or accepted. Findings revealed that the academic achievement on basic and integrated science process skills of the BS Biology students was average. Findings revealed that there are no significant differences on the academic performance of the BS Biology students when grouped according to year level and gender. Findings also revealed that there is a significant difference on the academic achievement between basic and integrated science process skills of the BS Biology students. Findings revealed that there is a significant relationship between academic achievement on the basic and integrated science process skills of the BS Biology students.

  13. Prevalence of hardcore smoking in the Netherlands between 2001 and 2012: a test of the hardening hypothesis

    Directory of Open Access Journals (Sweden)

    Jeroen Bommelé

    2016-08-01

    Full Text Available Abstract Background Hardcore smokers are smokers who have smoked for many years and who do not intend to quit smoking. The “hardening hypothesis” states that light smokers are more likely to quit smoking than heavy smokers (such as hardcore smokers. Therefore, the prevalence of hardcore smoking among smokers would increase over time. If this is true, the smoking population would become harder to reach with tobacco control measures. In this study we tested the hardening hypothesis. Methods We calculated the prevalence of hardcore smoking in the Netherlands from 2001 to 2012. Smokers were ‘hardcore’ if they a smoked every day, b smoked on average 15 cigarettes per day or more, c had not attempted to quit in the past 12 months, and d had no intention to quit within 6 months. We used logistic regression models to test whether the prevalence changed over time. We also investigated whether trends differed between educational levels. Results Among smokers, the prevalence of hardcore smoking decreased from 40.8 % in 2001 to 32.2 % in 2012. In the general population, it decreased from 12.2 to 8.2 %. Hardcore smokers were significantly lower educated than non-hardcore smokers. Among the general population, the prevalence of hardcore smoking decreased more among higher educated people than among lower educated people. Conclusions We found no support for the hardening hypothesis in the Netherlands between 2001 and 2012. Instead, the decrease of hardcore smoking among smokers suggests a ‘softening’ of the smoking population.

  14. Classification based hypothesis testing in neuroscience: Below-chance level classification rates and overlooked statistical properties of linear parametric classifiers.

    Science.gov (United States)

    Jamalabadi, Hamidreza; Alizadeh, Sarah; Schönauer, Monika; Leibold, Christian; Gais, Steffen

    2016-05-01

    Multivariate pattern analysis (MVPA) has recently become a popular tool for data analysis. Often, classification accuracy as quantified by correct classification rate (CCR) is used to illustrate the size of the effect under investigation. However, we show that in low sample size (LSS), low effect size (LES) data, which is typical in neuroscience, the distribution of CCRs from cross-validation of linear MVPA is asymmetric and can show classification rates considerably below what would be expected from chance classification. Conversely, the mode of the distribution in these cases is above expected chance levels, leading to a spuriously high number of above chance CCRs. This unexpected distribution has strong implications when using MVPA for hypothesis testing. Our analyses warrant the conclusion that CCRs do not well reflect the size of the effect under investigation. Moreover, the skewness of the null-distribution precludes the use of many standard parametric tests to assess significance of CCRs. We propose that MVPA results should be reported in terms of P values, which are estimated using randomization tests. Also, our results show that cross-validation procedures using a low number of folds, e.g. twofold, are generally more sensitive, even though the average CCRs are often considerably lower than those obtained using a higher number of folds. Hum Brain Mapp 37:1842-1855, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  15. Combining Multiple Hypothesis Testing with Machine Learning Increases the Statistical Power of Genome-wide Association Studies

    Science.gov (United States)

    Mieth, Bettina; Kloft, Marius; Rodríguez, Juan Antonio; Sonnenburg, Sören; Vobruba, Robin; Morcillo-Suárez, Carlos; Farré, Xavier; Marigorta, Urko M.; Fehr, Ernst; Dickhaus, Thorsten; Blanchard, Gilles; Schunk, Daniel; Navarro, Arcadi; Müller, Klaus-Robert

    2016-01-01

    The standard approach to the analysis of genome-wide association studies (GWAS) is based on testing each position in the genome individually for statistical significance of its association with the phenotype under investigation. To improve the analysis of GWAS, we propose a combination of machine learning and statistical testing that takes correlation structures within the set of SNPs under investigation in a mathematically well-controlled manner into account. The novel two-step algorithm, COMBI, first trains a support vector machine to determine a subset of candidate SNPs and then performs hypothesis tests for these SNPs together with an adequate threshold correction. Applying COMBI to data from a WTCCC study (2007) and measuring performance as replication by independent GWAS published within the 2008–2015 period, we show that our method outperforms ordinary raw p-value thresholding as well as other state-of-the-art methods. COMBI presents higher power and precision than the examined alternatives while yielding fewer false (i.e. non-replicated) and more true (i.e. replicated) discoveries when its results are validated on later GWAS studies. More than 80% of the discoveries made by COMBI upon WTCCC data have been validated by independent studies. Implementations of the COMBI method are available as a part of the GWASpi toolbox 2.0. PMID:27892471

  16. Testing the Sensory Drive Hypothesis: Geographic variation in echolocation frequencies of Geoffroy's horseshoe bat (Rhinolophidae: Rhinolophus clivosus).

    Science.gov (United States)

    Jacobs, David S; Catto, Sarah; Mutumi, Gregory L; Finger, Nikita; Webala, Paul W

    2017-01-01

    Geographic variation in sensory traits is usually influenced by adaptive processes because these traits are involved in crucial life-history aspects including orientation, communication, lineage recognition and mate choice. Studying this variation can therefore provide insights into lineage diversification. According to the Sensory Drive Hypothesis, lineage diversification may be driven by adaptation of sensory systems to local environments. It predicts that acoustic signals vary in association with local climatic conditions so that atmospheric attenuation is minimized and transmission of the signals maximized. To test this prediction, we investigated the influence of climatic factors (specifically relative humidity and temperature) on geographic variation in the resting frequencies of the echolocation pulses of Geoffroy's horseshoe bat, Rhinolophus clivosus. If the evolution of phenotypic variation in this lineage tracks climate variation, human induced climate change may lead to decreases in detection volumes and a reduction in foraging efficiency. A complex non-linear interaction between relative humidity and temperature affects atmospheric attenuation of sound and principal components composed of these correlated variables were, therefore, used in a linear mixed effects model to assess their contribution to observed variation in resting frequencies. A principal component composed predominantly of mean annual temperature (factor loading of -0.8455) significantly explained a proportion of the variation in resting frequency across sites (P < 0.05). Specifically, at higher relative humidity (around 60%) prevalent across the distribution of R. clivosus, increasing temperature had a strong negative effect on resting frequency. Climatic factors thus strongly influence acoustic signal divergence in this lineage, supporting the prediction of the Sensory Drive Hypothesis. The predicted future increase in temperature due to climate change is likely to decrease the

  17. Testing the Sensory Drive Hypothesis: Geographic variation in echolocation frequencies of Geoffroy's horseshoe bat (Rhinolophidae: Rhinolophus clivosus.

    Directory of Open Access Journals (Sweden)

    David S Jacobs

    Full Text Available Geographic variation in sensory traits is usually influenced by adaptive processes because these traits are involved in crucial life-history aspects including orientation, communication, lineage recognition and mate choice. Studying this variation can therefore provide insights into lineage diversification. According to the Sensory Drive Hypothesis, lineage diversification may be driven by adaptation of sensory systems to local environments. It predicts that acoustic signals vary in association with local climatic conditions so that atmospheric attenuation is minimized and transmission of the signals maximized. To test this prediction, we investigated the influence of climatic factors (specifically relative humidity and temperature on geographic variation in the resting frequencies of the echolocation pulses of Geoffroy's horseshoe bat, Rhinolophus clivosus. If the evolution of phenotypic variation in this lineage tracks climate variation, human induced climate change may lead to decreases in detection volumes and a reduction in foraging efficiency. A complex non-linear interaction between relative humidity and temperature affects atmospheric attenuation of sound and principal components composed of these correlated variables were, therefore, used in a linear mixed effects model to assess their contribution to observed variation in resting frequencies. A principal component composed predominantly of mean annual temperature (factor loading of -0.8455 significantly explained a proportion of the variation in resting frequency across sites (P < 0.05. Specifically, at higher relative humidity (around 60% prevalent across the distribution of R. clivosus, increasing temperature had a strong negative effect on resting frequency. Climatic factors thus strongly influence acoustic signal divergence in this lineage, supporting the prediction of the Sensory Drive Hypothesis. The predicted future increase in temperature due to climate change is likely to

  18. Why does Rhinopithecus bieti prefer the highest elevation range in winter? A test of the sunshine hypothesis.

    Directory of Open Access Journals (Sweden)

    Rui-Chang Quan

    Full Text Available Environmental factors that affect spatiotemporal distribution patterns of animals usually include resource availability, temperature, and the risk of predation. However, they do not explain the counterintuitive preference of high elevation range in winter by the black-and-white snub-nosed monkey (Rhinopithecus bieti. We asked whether variation of sunshine along with elevations is the key driving force. To test this hypothesis, we conducted field surveys to demonstrate that there was a statistically significant pattern of high elevation use during winter. We then asked whether this pattern can be explained by certain environmental factors, namely temperature, sunshine duration and solar radiation. Finally, we concluded with a possible ecological mechanism for this pattern. In this study, we employed GIS technology to quantify solar radiation and sunshine duration across the monkey's range. Our results showed that: 1 R. bieti used the high altitude range between 4100-4400 m in winter although the yearly home range spanned from 3500-4500 m; 2 both solar radiation and sunshine duration increased with elevation while temperature decreased with elevation; 3 within the winter range, the use of range was significantly correlated with solar radiation and sunshine duration; 4 monkeys moved to the areas with high solar radiation and duration following a snowfall, where the snow melts faster and food is exposed earlier. We concluded that sunshine was the main factor that influences selection of high elevation habitat for R. bieti in winter. Since some other endotherms in the area exhibit similar winter distributional patterns, we developed a sunshine hypothesis to explain this phenomenon. In addition, our work also represented a new method of integrating GIS models into traditional field ecology research to study spatiotemporal distribution pattern of wildlife. We suggest that further theoretical and empirical studies are necessary for better understanding

  19. CO2 emissions, real output, energy consumption, trade, urbanization and financial development: testing the EKC hypothesis for the USA.

    Science.gov (United States)

    Dogan, Eyup; Turkekul, Berna

    2016-01-01

    This study aims to investigate the relationship between carbon dioxide (CO2) emissions, energy consumption, real output (GDP), the square of real output (GDP(2)), trade openness, urbanization, and financial development in the USA for the period 1960-2010. The bounds testing for cointegration indicates that the analyzed variables are cointegrated. In the long run, energy consumption and urbanization increase environmental degradation while financial development has no effect on it, and trade leads to environmental improvements. In addition, this study does not support the validity of the environmental Kuznets curve (EKC) hypothesis for the USA because real output leads to environmental improvements while GDP(2) increases the levels of gas emissions. The results from the Granger causality test show that there is bidirectional causality between CO2 and GDP, CO2 and energy consumption, CO2 and urbanization, GDP and urbanization, and GDP and trade openness while no causality is determined between CO2 and trade openness, and gas emissions and financial development. In addition, we have enough evidence to support one-way causality running from GDP to energy consumption, from financial development to output, and from urbanization to financial development. In light of the long-run estimates and the Granger causality analysis, the US government should take into account the importance of trade openness, urbanization, and financial development in controlling for the levels of GDP and pollution. Moreover, it should be noted that the development of efficient energy policies likely contributes to lower CO2 emissions without harming real output.

  20. Gender differences in emotion perception and self-reported emotional intelligence: A test of the emotion sensitivity hypothesis

    Science.gov (United States)

    Kret, Mariska E.; Broekens, Joost

    2018-01-01

    Previous meta-analyses and reviews on gender differences in emotion recognition have shown a small to moderate female advantage. However, inconsistent evidence from recent studies has raised questions regarding the implications of different methodologies, stimuli, and samples. In the present research based on a community sample of more than 5000 participants, we tested the emotional sensitivity hypothesis, stating that women are more sensitive to perceive subtle, i.e. low intense or ambiguous, emotion cues. In addition, we included a self-report emotional intelligence test in order to examine any discrepancy between self-perceptions and actual performance for both men and women. We used a wide range of stimuli and models, displaying six different emotions at two different intensity levels. In order to better tap sensitivity for subtle emotion cues, we did not use a forced choice format, but rather intensity measures of different emotions. We found no support for the emotional sensitivity account, as both genders rated the target emotions as similarly intense at both levels of stimulus intensity. Men, however, more strongly perceived non-target emotions to be present than women. In addition, we also found that the lower scores of men in self-reported EI was not related to their actual perception of target emotions, but it was to the perception of non-target emotions. PMID:29370198

  1. Gender differences in emotion perception and self-reported emotional intelligence: A test of the emotion sensitivity hypothesis.

    Science.gov (United States)

    Fischer, Agneta H; Kret, Mariska E; Broekens, Joost

    2018-01-01

    Previous meta-analyses and reviews on gender differences in emotion recognition have shown a small to moderate female advantage. However, inconsistent evidence from recent studies has raised questions regarding the implications of different methodologies, stimuli, and samples. In the present research based on a community sample of more than 5000 participants, we tested the emotional sensitivity hypothesis, stating that women are more sensitive to perceive subtle, i.e. low intense or ambiguous, emotion cues. In addition, we included a self-report emotional intelligence test in order to examine any discrepancy between self-perceptions and actual performance for both men and women. We used a wide range of stimuli and models, displaying six different emotions at two different intensity levels. In order to better tap sensitivity for subtle emotion cues, we did not use a forced choice format, but rather intensity measures of different emotions. We found no support for the emotional sensitivity account, as both genders rated the target emotions as similarly intense at both levels of stimulus intensity. Men, however, more strongly perceived non-target emotions to be present than women. In addition, we also found that the lower scores of men in self-reported EI was not related to their actual perception of target emotions, but it was to the perception of non-target emotions.

  2. Glucocorticoid excess and the developmental origins of disease: two decades of testing the hypothesis--2012 Curt Richter Award Winner.

    Science.gov (United States)

    Reynolds, Rebecca M

    2013-01-01

    Low birthweight, a marker of an adverse in utero environment, is associated with cardiometabolic disease and brain disorders in adulthood. The adaptive changes made by the fetus in response to the intra-uterine environment result in permanent changes in physiology, structure and metabolism, a phenomenon termed early life programming. One of the key hypotheses to explain programming, namely over exposure of the developing fetus to glucocorticoids, was proposed nearly two decades ago, following the observation that the fetus was protected from high glucocorticoid levels in the mother by the actions of the placental barrier enzyme, 11β-hydroxysteroid dehydrogenase, which converts active glucocorticoids into inactive products. Numerous mechanistic studies in animal models have been carried out to test this hypothesis using manipulations to increase maternal glucocorticoids. Overall, these have resulted in offspring of lower birthweight, with an activated hypothalamic-pituitary-adrenal (HPA) axis and an adverse metabolic profile and behavioural phenotype in adulthood. Altered glucocorticoid activity or action is a good candidate mechanism in humans to link low birthweight with cardiometabolic and brain disorders. We have carried out detailed studies in men and women showing that high levels of endogenous glucocorticoids, or treatment with exogenous glucocorticoids, is associated with an adverse metabolic profile, increased cardiovascular disease and altered mood and cognitive decline. Our laboratory carried out the first translational studies in humans to test the glucocorticoid hypothesis, firstly demonstrating in studies of adult men and women, that low birthweight was associated with high fasting cortisol levels. We went on to dissect the mechanisms underlying the high fasting cortisol, demonstrating activation of the HPA axis, with increased cortisol responses to stimulation with exogenous adrenocorticotrophin hormone, lack of habituation to the stress of

  3. Using a Simple Binomial Model to Assess Improvement in Predictive Capability: Sequential Bayesian Inference, Hypothesis Testing, and Power Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sigeti, David E. [Los Alamos National Laboratory; Pelak, Robert A. [Los Alamos National Laboratory

    2012-09-11

    We present a Bayesian statistical methodology for identifying improvement in predictive simulations, including an analysis of the number of (presumably expensive) simulations that will need to be made in order to establish with a given level of confidence that an improvement has been observed. Our analysis assumes the ability to predict (or postdict) the same experiments with legacy and new simulation codes and uses a simple binomial model for the probability, {theta}, that, in an experiment chosen at random, the new code will provide a better prediction than the old. This model makes it possible to do statistical analysis with an absolute minimum of assumptions about the statistics of the quantities involved, at the price of discarding some potentially important information in the data. In particular, the analysis depends only on whether or not the new code predicts better than the old in any given experiment, and not on the magnitude of the improvement. We show how the posterior distribution for {theta} may be used, in a kind of Bayesian hypothesis testing, both to decide if an improvement has been observed and to quantify our confidence in that decision. We quantify the predictive probability that should be assigned, prior to taking any data, to the possibility of achieving a given level of confidence, as a function of sample size. We show how this predictive probability depends on the true value of {theta} and, in particular, how there will always be a region around {theta} = 1/2 where it is highly improbable that we will be able to identify an improvement in predictive capability, although the width of this region will shrink to zero as the sample size goes to infinity. We show how the posterior standard deviation may be used, as a kind of 'plan B metric' in the case that the analysis shows that {theta} is close to 1/2 and argue that such a plan B should generally be part of hypothesis testing. All the analysis presented in the paper is done with a

  4. Are children's faces really more appealing than those of adults? Testing the baby schema hypothesis beyond infancy.

    Science.gov (United States)

    Luo, Li Zhu; Li, Hong; Lee, Kang

    2011-09-01

    This study examined adults' evaluations of likeability and attractiveness of children's faces from infancy to early childhood. We tested whether Lorenz's baby schema hypothesis (Zeitschrift für Tierpsychologie (1943), Vol. 5, pp. 235-409) is applicable not only to infant faces but also to faces of children at older ages. Adult participants were asked to evaluate children's faces from early infancy to 6 years of age in terms of their likeability and attractiveness, and these judgments were compared with those of adult faces. It was revealed that adults judged faces of younger children as more likeable and attractive than faces of older children, which were in turn judged as more likeable and attractive than adult faces. However, after approximately 4.5 years of age, the baby schema no longer affected adults' judgments of children's facial likeability and attractiveness. These findings suggest that the baby schema affects adults' judgments of not only infant faces but also young children's faces. This influence beyond infancy is likely due to the fact that facial cranial growth is gradual during early childhood and certain crucial infantile facial cues remain readily available during this period. Future studies need to identify these specific cues to better understand why adults generally show positive responses to infantile faces and how such positive responses influence the establishment and maintenance of social relationships between young children and adults. Copyright © 2011 Elsevier Inc. All rights reserved.

  5. The influence of maternal acculturation, neighborhood disadvantage, and parenting on Chinese American adolescents' conduct problems: testing the segmented assimilation hypothesis.

    Science.gov (United States)

    Liu, Lisa L; Lau, Anna S; Chen, Angela Chia-Chen; Dinh, Khanh T; Kim, Su Yeong

    2009-05-01

    Associations among neighborhood disadvantage, maternal acculturation, parenting and conduct problems were investigated in a sample of 444 Chinese American adolescents. Adolescents (54% female, 46% male) ranged from 12 to 15 years of age (mean age = 13.0 years). Multilevel modeling was employed to test the hypothesis that the association between maternal acculturation and adolescents' conduct problems could be explained by differences in mothers' reliance on monitoring and harsh discipline. In addition, guided by segmented assimilation theory, measures of neighborhood disadvantage were expected not only to be related to differences in parenting, but also to moderate the effects of maternal acculturation on parenting. Results indicated that increased maternal acculturation was related to higher levels of maternal monitoring and lower levels of harsh discipline, which, in turn, were related to lower levels of adolescents' conduct problems. Hierarchical linear modeling results revealed that neighborhood disadvantage was related to lower levels of maternal monitoring. However, neighborhood disadvantage did not moderate the link between maternal acculturation and parenting practices.

  6. Testing the Expectations Hypothesis of the Term Structure of Interest Rates in BRICS Countries: A Multivariate Co-integration Approach

    Directory of Open Access Journals (Sweden)

    Paul Francois Muzindutsi

    2016-08-01

    Full Text Available The BRICS is a group of major emerging economies in the world which have combined financial resources to form the New Development Bank in an effort to address economic challenges faced by these countries. Thus, the flow of funds among the BRICS countries are expected to increase and this has implication on interest rates changes in these countries. Employing monthly short and long term interest rates from June 2005 to June 2015, this study used a multivariate cointegration approach to test for the validity of the expectations hypothesis (EH of the term structure of interest rates in BRICS countries. The results of the co-integration analysis revealed that the EH only holds in three of the five countries, namely China, India, and South Africa. Short and long term interest rates for these three countries converge to the long-run equilibrium at different speed, where the convergence was found to be quick in South Africa and slow in China. This study found no evidence of EH in Brazil and Russia. Findings of this study are relevant to current developments within BRICS financial markets and provide valuable information that can be used to forecast future changes in interest rates in BRICS countries.

  7. Does leaf shedding protect stems from cavitation during seasonal droughts? A test of the hydraulic fuse hypothesis.

    Science.gov (United States)

    Wolfe, Brett T; Sperry, John S; Kursar, Thomas A

    2016-12-01

    During droughts, leaves are predicted to act as 'hydraulic fuses' by shedding when plants reach critically low water potential (Ψ plant ), thereby slowing water loss, stabilizing Ψ plant and protecting against cavitation-induced loss of stem hydraulic conductivity (K s ). We tested these predictions among trees in seasonally dry tropical forests, where leaf shedding is common, yet variable, among species. We tracked leaf phenology, Ψ plant and K s in saplings of six tree species distributed across two forests. Species differed in their timing and extent of leaf shedding, yet converged in shedding leaves as they approached the Ψ plant value associated with a 50% loss of K s and at which their model-estimated maximum sustainable transpiration rate approached zero. However, after shedding all leaves, the Ψ plant value of one species, Genipa americana, continued to decline, indicating that water loss continued after leaf shedding. K s was highly variable among saplings within species and seasons, suggesting a minimal influence of seasonal drought on K s . Hydraulic limits appear to drive diverse patterns of leaf shedding among tropical trees, supporting the hydraulic fuse hypothesis. However, leaf shedding is not universally effective at stabilizing Ψ plant , suggesting that the main function of drought deciduousness may vary among species. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  8. Coordination of stem and leaf hydraulic conductance in southern California shrubs: a test of the hydraulic segmentation hypothesis.

    Science.gov (United States)

    Pivovaroff, Alexandria L; Sack, Lawren; Santiago, Louis S

    2014-08-01

    Coordination of water movement among plant organs is important for understanding plant water use strategies. The hydraulic segmentation hypothesis (HSH) proposes that hydraulic conductance in shorter lived, 'expendable' organs such as leaves and longer lived, more 'expensive' organs such as stems may be decoupled, with resistance in leaves acting as a bottleneck or 'safety valve'. We tested the HSH in woody species from a Mediterranean-type ecosystem by measuring leaf hydraulic conductance (Kleaf) and stem hydraulic conductivity (KS). We also investigated whether leaves function as safety valves by relating Kleaf and the hydraulic safety margin (stem water potential minus the water potential at which 50% of conductivity is lost (Ψstem-Ψ50)). We also examined related plant traits including the operating range of water potentials, wood density, leaf mass per area, and leaf area to sapwood area ratio to provide insight into whole-plant water use strategies. For hydrated shoots, Kleaf was negatively correlated with KS , supporting the HSH. Additionally, Kleaf was positively correlated with the hydraulic safety margin and negatively correlated with the leaf area to sapwood area ratio. Consistent with the HSH, our data indicate that leaves may act as control valves for species with high KS , or a low safety margin. This critical role of leaves appears to contribute importantly to plant ecological specialization in a drought-prone environment. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  9. Influence of prey dispersion on territory and group size of African lions: a test of the resource dispersion hypothesis.

    Science.gov (United States)

    Valeix, Marion; Loveridge, Andrew J; MacDonald, David W

    2012-11-01

    Empirical tests of the resource dispersion hypothesis (RDH), a theory to explain group living based on resource heterogeneity, have been complicated by the fact that resource patch dispersion and richness have proved difficult to define and measure in natural systems. Here, we studied the ecology of African lions Panthera leo in Hwange National Park, Zimbabwe, where waterholes are prey hotspots, and where dispersion of water sources and abundance of prey at these water sources are quantifiable. We combined a 10-year data set from GPS-collared lions for which information of group composition was available concurrently with data for herbivore abundance at waterholes. The distance between two neighboring waterholes was a strong determinant of lion home range size, which provides strong support for the RDH prediction that territory size increases as resource patches are more dispersed in the landscape. The mean number of herbivore herds using a waterhole, a good proxy of patch richness, determined the maximum lion group biomass an area can support. This finding suggests that patch richness sets a maximum ceiling on lion group size. This study demonstrates that landscape ecology is a major driver of ranging behavior and suggests that aspects of resource dispersion limit group sizes.

  10. Thermal analysis of biological shield of fast breeder test reactor

    International Nuclear Information System (INIS)

    Saha, D.; Sarda, V.

    1976-01-01

    A design optimisation of the biological shield of fast breeder test reactor was carried out using computer code HEATING. The effect of different heat sources, variation of coolant tube pitch circle radius, coolant temperature, angular pitch of coolant tubes and thermal conductivity of concrete on the temperature distribution within the shield has been studied. (author)

  11. Testing the out-of-Florida hypothesis on the origin of cheating in the yucca-yucca moth mutualism.

    Science.gov (United States)

    Segraves, Kari A; Pellmyr, Olle

    2004-10-01

    Mutualistic interactions can be exploited by cheaters that take the rewards offered by mutualists without providing services in return. The evolution of cheater species from mutualist ancestors is thought to be possible under particular ecological conditions. Here we provide a test of the first explicit model of the transition from mutualism to antagonism. We used the obligate pollination mutualism between yuccas and yucca moths to examine the origins of a nonpollinating cheater moth, Tegeticula intermedia, and its pollinating sister species, T. cassandra. Based on geographic distribution and ecological factors affecting the pollinators, previous research had indicated that the cheaters evolved in Florida as a result of sympatry of T. cassandra and another pollinator species. We used mitochondrial DNA (mtDNA) sequences and amplified fragment length polymorphism (AFLP) data to investigate the phylogeographic history of the pollinator-cheater sister pair and to test whether the cheaters arose in Florida. Contrary to predictions, phylogenetic and population genetic analyses suggested that the cheaters evolved in the western United States and subsequently spread eastward. Western populations of cheaters had the most ancestral haplotypes and the highest genetic diversity, and there was also significant genetic structure associated with a geographic split between eastern and western populations. In comparison, there was evidence for weak genetic structure between northern and southern pollinator populations, suggesting a long history in Florida. The western origin of the cheaters indicated that the pollinators have more recently become restricted to the southeastern United States. This was supported by AFLP analyses that indicated that the pollinators were more closely related to the western cheaters than they were to geographically proximate cheaters in the east. Shared mtDNA between pollinators and eastern cheaters suggested hybridization, possibly in a secondary

  12. Pulse Duplicator Hydrodynamic Testing of Bioengineered Biological Heart Valves.

    Science.gov (United States)

    Buse, Eric E; Hilbert, Stephen L; Hopkins, Richard A; Converse, Gabriel L

    2016-12-01

    There are many heart valve replacements currently available on the market; however, these devices are not ideal for pediatric patients with congenital heart valve defects. Decellularized valve substitutes offer potential for improved clinical outcomes and require pre-clinical testing guidelines and testing systems suitable for non-crosslinked, biological heart valves. The objective of this study was to assess the hydrodynamic performance of intact, bioengineered pulmonary valves using a custom pulse duplicator capable of testing intact biological valved conduits. The mechanical behavior of valve associated sinus and arterial tissue was also evaluated under biaxial loading. Cryopreserved, decellularized, extracellular matrix (ECM) conditioned and glutaraldehyde fixed valves showed reduced pressure gradients and increased effective orifice area for decellularized and ECM conditioned valves. ECM conditioning resulted in increased elastic modulus but decreased stretch in circumferential and longitudinal directions under biaxial loading. Overall, decellularization and ECM conditioning did not compromise the scaffolds, which exhibited satisfactory bench top performance.

  13. Rationale and Design of the Cardiovascular Inflammation Reduction Trial (CIRT): A Test of the Inflammatory Hypothesis of Atherothrombosis

    Science.gov (United States)

    Everett, Brendan M.; Pradhan, Aruna D.; Solomon, Daniel H.; Paynter, Nina; MacFadyen, Jean; Zaharris, Elaine; Gupta, Milan; Clearfield, Michael; Libby, Peter; Hasan, Ahmed AK; Glynn, Robert J.; Ridker, Paul M

    2013-01-01

    Background Inflammation plays a fundamental role in atherothrombosis. Yet, whether direct inhibition of inflammation will reduce the occurrence of adverse cardiovascular outcomes is not known. Design The Cardiovascular Inflammation Reduction Trial (CIRT; ClinicalTrials.gov NCT01594333) will randomly allocate 7,000 patients with prior myocardial infarction and either type 2 diabetes or the metabolic syndrome to low dose methotrexate (target dose 15 to 20 mg per week) or placebo over an average follow-up period of 3 to 5 years. Low-dose methotrexate is a commonly used anti-inflammatory regimen for the treatment of rheumatoid arthritis, lacks significant effects on lipid levels, blood pressure, or platelet function. Both observational and mechanistic studies suggest that low-dose methotrexate has clinically relevant anti-atherothrombotic effects. The CIRT primary endpoint is a composite of nonfatal myocardial infarction, nonfatal stroke, and cardiovascular death. Secondary endpoints are all-cause mortality, coronary revascularization plus the primary endpoint, hospitalization for congestive heart failure plus the primary endpoint, all-cause mortality plus coronary revascularization plus congestive heart failure plus the primary endpoint, incident type 2 diabetes, and net clinical benefit or harm. CIRT will employ standardized central methodology designed to ensure consistent performance of all dose adjustments and safety interventions at each clinical site in a manner that protects the blinding to treatment but maintains safety for enrolled participants. Summary CIRT aims to test the inflammatory hypothesis of atherothrombosis in patients with prior myocardial infarction and either type 2 diabetes or metabolic syndrome, conditions associated with persistent inflammation. If low-dose methotrexate reduces cardiovascular events, CIRT would provide a novel therapeutic approach for the secondary prevention of heart attack, stroke, and cardiovascular death. (Clinical Trial

  14. Testing the status-legitimacy hypothesis: A multilevel modeling approach to the perception of legitimacy in income distribution in 36 nations.

    Science.gov (United States)

    Caricati, Luca

    2017-01-01

    The status-legitimacy hypothesis was tested by analyzing cross-national data about social inequality. Several indicators were used as indexes of social advantage: social class, personal income, and self-position in the social hierarchy. Moreover, inequality and freedom in nations, as indexed by Gini and by the human freedom index, were considered. Results from 36 nations worldwide showed no support for the status-legitimacy hypothesis. The perception that income distribution was fair tended to increase as social advantage increased. Moreover, national context increased the difference between advantaged and disadvantaged people in the perception of social fairness: Contrary to the status-legitimacy hypothesis, disadvantaged people were more likely than advantaged people to perceive income distribution as too large, and this difference increased in nations with greater freedom and equality. The implications for the status-legitimacy hypothesis are discussed.

  15. Evolution of sexual dichromatism in relation to nesting habits in European passerines: a test of Wallace's hypothesis.

    Science.gov (United States)

    Soler, J J; Moreno, J

    2012-08-01

    Wallace proposed in 1868 that natural rather than sexual selection could explain the striking differences in avian plumage dichromatism. Thus, he predicted that nesting habits, through their association with nest predation, could drive changes in sexual dichromatism by enabling females in cavity nesters to become as conspicuous as males, whereas Darwin (1871, The Descent of Man and Selection in Relation to Sex, John Murray, London) argued that sexual selection was the sole explanation for dichromatism. Sexual dichromatism is currently used as indicating the strength of sexual selection, and therefore testing Wallace's claim with modern phylogentically controlled methodologies is of prime interest for comparing the roles of natural and sexual selection in affecting the evolution of avian coloration. Here, we have related information on nest attendance, sexual dichromatism and nesting habits (open and cavity nesting) to male and female plumage conspicuousness in European passerines. Nest incubation attendance does not explain male or female plumage conspicuousness but nest type does. Moreover, although females of monochromatic and cavity nesting species are more conspicuous than females of other species, males of monochromatic and open nesting species are those with more cryptic plumage. Finally, analyses of character evolution suggest that changes in nesting habits influence the probability of changes in both dichromatism and plumage conspicuousness of males but do not significantly affect those in females. These results strongly suggest a role of nesting habits in the evolution of plumage conspicuousness of males, and a role for sexual selection also in females, both factors affecting the evolution of sexual dichromatism. We discuss our findings in relation to the debate that Darwin and Wallace maintained more than one century ago on the importance of natural and sexual selection in driving the evolution of plumage conspicuousness and sexual dichromatism in birds

  16. Testing Orbital Parameters as a Hypothesis for the Presence of CO2 Deposits on Mars's South Pole

    Science.gov (United States)

    Bain, Z. M.; Bierson, C. J.

    2017-12-01

    Observational data of Mars's polar caps shows large deposits of buried CO2 ice in the south polar cap and only seasonal CO2 ice in the north [1]. The lower elevation of Mars's north pole leads to higher surface pressures and therefore more favorable conditions for CO2 ice deposition. There are a few plausible reasons why the CO2 deposits are observed at the southern cap. The first is that during a past epochs of atmospheric collapse, CO2was deposited at both poles and only preserved in the south. Another is that the deposits represent a period where ice was preferentially deposited at the south polar cap. The latter could occur if the orbital parameters were such that the southern cap experienced colder summers (less insolation) than the north. The model of Bierson et. al. 2016 [2] used the observed difference in albedo between the north and the south polar caps and found several periods in the last one million years where deposition was favored at the south polar cap. Here we test if deposition is still favored in the south using the same albedo for both caps. For this work we are using the seasonally resolved KRC model [3]. We varied obliquity, longitude of perihelion, and eccentricity to match their expected values over the last one million years [4]. We modeled the annual CO2 deposition rate in 1,000 year increments. We tested both constant and insolation dependent albedo that was the same at both poles. While we did find periods of deposition on the south pole, this was always in conjunction with deposition in the north in much greater amounts. This finding favors the hypothesis that the deposits are only observed in the southern cap due to the deep pre-existing troughs that allowed the CO2 to be preserved to the modern day. These results also highlight the importance of understanding the observed difference in albedo between the polar caps. [1] Phillips et al. (2011) AAAS, Vol.332 Is.6031 pp.838-841 [2] Bierson et al. (2016) GRL, Vol.43 Is.9 pp.4172-4179 [3

  17. Testing of Synthetic Biological Membranes for Forward Osmosis Applications

    Science.gov (United States)

    Parodi, Jurek; Mangado, Jaione Romero; Stefanson, Ofir; Flynn, Michael; Mancinelli, Rocco; Kawashima, Brian; Trieu, Serena; Brozell, Adrian; Rosenberg, Kevan

    2016-01-01

    Commercially available forward osmosis membranes have been extensively tested for human space flight wastewater treatment. Despite the improvements achieved in the last decades, there is still a challenge to produce reliable membranes with anti-fouling properties, chemical resistance, and high flux and selectivity. Synthetic biological membranes that mimic the ones present in nature, which underwent millions of years of evolution, represent a potential solution for further development and progress in membrane technology. Biomimetic forward osmosis membranes based on a polymeric support filter and coated with surfactant multilayers have been engineered to investigate how different manufacturing processes impact the performance and structure of the membrane. However, initial results of the first generation prototype membranes tests reveal a high scatter in the data, due to the current testing apparatus set up. The testing apparatus has been upgraded to improve data collection, reduce errors, and to allow higher control of the testing process.

  18. A Test of the Transdiagnostic Dopamine Hypothesis of Psychosis Using Positron Emission Tomographic Imaging in Bipolar Affective Disorder and Schizophrenia.

    Science.gov (United States)

    Jauhar, Sameer; Nour, Matthew M; Veronese, Mattia; Rogdaki, Maria; Bonoldi, Ilaria; Azis, Matilda; Turkheimer, Federico; McGuire, Philip; Young, Allan H; Howes, Oliver D

    2017-12-01

    The dopamine hypothesis suggests that dopamine abnormalities underlie psychosis, irrespective of diagnosis, implicating dopamine dysregulation in bipolar affective disorder and schizophrenia, in line with the research domain criteria approach. However, this hypothesis has not been directly examined in individuals diagnosed with bipolar disorder with psychosis. To test whether dopamine synthesis capacity is elevated in bipolar disorder with psychosis and how this compares with schizophrenia and matched controls and to examine whether dopamine synthesis capacity is associated with psychotic symptom severity, irrespective of diagnostic class. This cross-sectional case-control positron emission tomographic study was performed in the setting of first-episode psychosis services in an inner-city area (London, England). Sixty individuals participated in the study (22 with bipolar psychosis [18 antipsychotic naive or free], 16 with schizophrenia [14 antipsychotic naive or free], and 22 matched controls) and underwent fluorodihydroxyphenyl-l-alanine ([18F]-DOPA) positron emission tomography to examine dopamine synthesis capacity. Standardized clinical measures, including the Positive and Negative Syndrome Scale, Young Mania Rating Scale, and Global Assessment of Functioning, were administered. The study dates were March 2013 to November 2016. Dopamine synthesis capacity (Kicer) and clinical measures (Positive and Negative Syndrome Scale, Young Mania Rating Scale, and Global Assessment of Functioning). The mean (SD) ages of participants were 23.6 (3.6) years in 22 individuals with bipolar psychosis (13 male), 26.3 (4.4) years in 16 individuals with schizophrenia (14 male), and 24.5 (4.5) years in controls (14 male). There was a significant group difference in striatal dopamine synthesis capacity (Kicer) (F2,57 = 6.80, P = .002). Kicer was significantly elevated in both the bipolar group (mean [SD], 13.18 [1.08] × 10-3 min-1; P = .002) and the schizophrenia

  19. Wave basin model tests of technical-biological bank protection

    Science.gov (United States)

    Eisenmann, J.

    2012-04-01

    Sloped embankments of inland waterways are usually protected from erosion and other negative im-pacts of ship-induced hydraulic loads by technical revetments consisting of riprap. Concerning the dimensioning of such bank protection there are several design rules available, e.g. the "Principles for the Design of Bank and Bottom Protection for Inland Waterways" or the Code of Practice "Use of Standard Construction Methods for Bank and Bottom Protection on Waterways" issued by the BAW (Federal Waterways Engineering and Research Institute). Since the European Water Framework Directive has been put into action special emphasis was put on natural banks. Therefore the application of technical-biological bank protection is favoured. Currently design principles for technical-biological bank protection on inland waterways are missing. The existing experiences mainly refer to flowing waters with no or low ship-induced hydraulic loads on the banks. Since 2004 the Federal Waterways Engineering and Research Institute has been tracking the re-search and development project "Alternative Technical-Biological Bank Protection on Inland Water-ways" in company with the Federal Institute of Hydrology. The investigation to date includes the ex-amination of waterway sections where technical- biological bank protection is applied locally. For the development of design rules for technical-biological bank protection investigations shall be carried out in a next step, considering the mechanics and resilience of technical-biological bank protection with special attention to ship-induced hydraulic loads. The presentation gives a short introduction into hydraulic loads at inland waterways and their bank protection. More in detail model tests of a willow brush mattress as a technical-biological bank protec-tion in a wave basin are explained. Within the scope of these tests the brush mattresses were ex-posed to wave impacts to determine their resilience towards hydraulic loads. Since the

  20. Testing the saprobity hypothesis in a Mediterranean lagoon: effects of confinement and organic enrichment on benthic communities.

    Science.gov (United States)

    Foti, A; Fenzi, G A; Di Pippo, F; Gravina, M F; Magni, P

    2014-08-01

    The macrobenthic community was compared at four sites characterized by varying degrees of freshwater input, organic enrichment and confinement in the Cabras lagoon (Sardinia, Italy). Three sites, riverine (C1), confined (C2) and seaward (C3), were studied on two dates of summer 2010 and on two dates of winter 2011. A fourth site (C12), representative of the central sector of the Cabras lagoon, was included in this study using the extensive historical datasets at our disposal from previously published work. We aimed to test the hypothesis that (1) the benthos is distributed according to the recently proposed concept of habitat saprobity for coastal lagoons that unifies the Pearson-Rosenberg (sensu organic enrichment) and Guélorget-Perthuisot (sensu confinement) models, and (2) indicator species of different saprobic levels can be identified among dominant species occurring along the saprobity gradient. Salinity was also considered as an additional agent of selection in brackish environments. Irrespective of significant seasonal changes within each site, our results highlighted major environmental and biotic differences between sites. At the northward riverine site (C1), most affected by freshwater input and with limited organic matter (OM) enrichment, Corophium orientale was the single dominant species. The most confined site (C2) was characterized by the highest levels of sedimentary OM and benthic Chlorophyll-a and by mesohaline conditions; the site was inhabited mainly by the halolimnobic Hediste diversicolor and Hydrobia spp. Site C12, characterized by a high OM load and high residence time, was dominated by the opportunistic detritivorous Alitta succinea and Polydora ciliata. At the southernmost seaward site (C3) the considerable seawater renewal, resulting in high salinity (only in summer) and limited OM load, favored a much more diverse macrobenthic assemblage, essentially composed of both marine species, such as Corophium insidiosum, Gammarus aequicauda

  1. On-line Flagging of Anomalies and Adaptive Sequential Hypothesis Testing for Fine-feature Characterization of Geosynchronous Satellites

    Science.gov (United States)

    Chaudhary, A.; Payne, T.; Kinateder, K.; Dao, P.; Beecher, E.; Boone, D.; Elliott, B.

    The objective of on-line flagging in this paper is to perform interactive assessment of geosynchronous satellites anomalies such as cross-tagging of a satellites in a cluster, solar panel offset change, etc. This assessment will utilize a Bayesian belief propagation procedure and will include automated update of baseline signature data for the satellite, while accounting for the seasonal changes. Its purpose is to enable an ongoing, automated assessment of satellite behavior through its life cycle using the photometry data collected during the synoptic search performed by a ground or space-based sensor as a part of its metrics mission. The change in the satellite features will be reported along with the probabilities of Type I and Type II errors. The objective of adaptive sequential hypothesis testing in this paper is to define future sensor tasking for the purpose of characterization of fine features of the satellite. The tasking will be designed in order to maximize new information with the least number of photometry data points to be collected during the synoptic search by a ground or space-based sensor. Its calculation is based on the utilization of information entropy techniques. The tasking is defined by considering a sequence of hypotheses in regard to the fine features of the satellite. The optimal observation conditions are then ordered in order to maximize new information about a chosen fine feature. The combined objective of on-line flagging and adaptive sequential hypothesis testing is to progressively discover new information about the features of a geosynchronous satellites by leveraging the regular but sparse cadence of data collection during the synoptic search performed by a ground or space-based sensor. Automated Algorithm to Detect Changes in Geostationary Satellite's Configuration and Cross-Tagging Phan Dao, Air Force Research Laboratory/RVB By characterizing geostationary satellites based on photometry and color photometry, analysts can

  2. Is the fluid mosaic (and the accompanying raft hypothesis a suitable model to describe fundamental features of biological membranes? What may be missing?

    Directory of Open Access Journals (Sweden)

    Luis Alberto Bagatolli

    2013-11-01

    Full Text Available The structure, dynamics, and stability of lipid bilayers are controlled by thermodynamic forces, leading to overall tensionless membranes with a distinct lateral organization and a conspicuous lateral pressure profile. Bilayers are also subject to built-in curvature-stress instabilities that may be released locally or globally in terms of morphological changes leading to the formation of non-lamellar and curved structures. A key controller of the bilayer’s propensity to form curved structures is the average molecular shape of the different lipid molecules. Via the curvature stress, molecular shape mediates a coupling to membrane-protein function and provides a set of physical mechanisms for formation of lipid domains and laterally differentiated regions in the plane of the membrane. Unfortunately, these relevant physical features of membranes are often ignored in the most popular models for biological membranes. Results from a number of experimental and theoretical studies emphasize the significance of these fundamental physical properties and call for a refinement of the fluid mosaic model (and the accompanying raft hypothesis.

  3. Born to win? Testing the fighting hypothesis in realistic fights : left-handedness in the Ultimate Fighting Championship

    NARCIS (Netherlands)

    Pollet, Thomas V.; Stulp, Gert; Groothuis, Ton G. G.

    2013-01-01

    Given the heritability of human left-handedness and its purported associations with fitness-lowering traits, the persistence of the minority of left-handedness in human populations is an evolutionary puzzle. The fighting hypothesis proposes that these negative fitness costs are offset by fitness

  4. Born to win? Testing the fighting hypothesis in realistic fights: left-handedness in the Ultimate Fighting Championship

    NARCIS (Netherlands)

    Pollet, T.V.; Stulp, G.; Groothuis, T.G.G.

    2013-01-01

    Given the heritability of human left-handedness and its purported associations with fitness-lowering traits, the persistence of the minority of left-handedness in human populations is an evolutionary puzzle. The fighting hypothesis proposes that these negative fitness costs are offset by fitness

  5. Biocentricity and economy of scale : hypothesis (and product) testing when wood is a part of an experimental system evaluating durability

    Science.gov (United States)

    Alex C. Wiedenhoeft

    2009-01-01

    Wood is a biological material, and its structure and organization are relicts of its biogenesis. From the hydrogen bonding of water molecules in the cell wall to extractives bleeding from knots in siding, the characteristics and behavior of wood are derived from its biological origin; this is my unashamedly biocentric view of wood structure. The structure of wood...

  6. Nondestructive mechanical characterization of developing biological tissues using inflation testing.

    Science.gov (United States)

    Oomen, P J A; van Kelle, M A J; Oomens, C W J; Bouten, C V C; Loerakker, S

    2017-10-01

    One of the hallmarks of biological soft tissues is their capacity to grow and remodel in response to changes in their environment. Although it is well-accepted that these processes occur at least partly to maintain a mechanical homeostasis, it remains unclear which mechanical constituent(s) determine(s) mechanical homeostasis. In the current study a nondestructive mechanical test and a two-step inverse analysis method were developed and validated to nondestructively estimate the mechanical properties of biological tissue during tissue culture. Nondestructive mechanical testing was achieved by performing an inflation test on tissues that were cultured inside a bioreactor, while the tissue displacement and thickness were nondestructively measured using ultrasound. The material parameters were estimated by an inverse finite element scheme, which was preceded by an analytical estimation step to rapidly obtain an initial estimate that already approximated the final solution. The efficiency and accuracy of the two-step inverse method was demonstrated on virtual experiments of several material types with known parameters. PDMS samples were used to demonstrate the method's feasibility, where it was shown that the proposed method yielded similar results to tensile testing. Finally, the method was applied to estimate the material properties of tissue-engineered constructs. Via this method, the evolution of mechanical properties during tissue growth and remodeling can now be monitored in a well-controlled system. The outcomes can be used to determine various mechanical constituents and to assess their contribution to mechanical homeostasis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Testing the Fundamental Difference Hypothesis: L2 Adult, L2 Child, and L1 Child Comparisons in the Acquisition of Korean "Wh"-Constructions with Negative Polarity Items

    Science.gov (United States)

    Song, Hyang Suk; Schwartz, Bonnie D.

    2009-01-01

    The fundamental difference hypothesis (FDH; Bley-Vroman, 1989, 1990) contends that the nature of language in natives is fundamentally different from the nature of language in adult nonnatives. This study tests the FDH in two ways: (a) via second language (L2) poverty-of-the-stimulus (POS) problems (e.g., Schwartz & Sprouse, 2000) and (b) via a…

  8. Should Soil Testing Services Measure Soil Biological Activity?

    Directory of Open Access Journals (Sweden)

    Alan J. Franzluebbers

    2016-02-01

    Full Text Available Health of agricultural soils depends largely on conservation management to promote soil organic matter accumulation. Total soil organic matter changes slowly, but active fractions are more dynamic. A key indicator of healthy soil is potential biological activity, which could be measured rapidly with soil testing services via the flush of CO during 1 to 3 d following rewetting of dried soil. The flush of CO is related to soil microbial biomass C and has repeatedly been shown strongly related to net N mineralization during standard aerobic incubations. New research is documenting the close association with plant N uptake in semicontrolled greenhouse conditions ( = 0.77, = 36. Field calibrations are underway to relate the flush of CO to the need for in-season N requirement in a variety of crops. An index of soil biological activity can and should be determined to help predict soil health and soil N availability.

  9. The Unique Relations between Early Homelessness and Educational Well-Being: An Empirical Test of the Continuum of Risk Hypothesis.

    Science.gov (United States)

    Brumley, Benjamin; Fantuzzo, John; Perlman, Staci; Zager, Margaret L

    2015-01-01

    This study examined the Continuum of Risk Hypothesis by assessing the unique relations between early homelessness and educational outcomes while controlling for co-occurring risks. An integrated data system was used to account for multiple co-occurring early risk factors for an entire cohort of first grade students in a large urban school district and municipality (N = 8,267). Multilevel linear regression models indicated that the presence of some co-occurring risk factors explained the relation between homelessness and academic engagement problems in school. However, after controlling for co-occurring risks, an experience of homelessness was found to be uniquely related to social engagement problems in first grade. These results support the Continuum of Risk Hypothesis and stress the importance of early intervention for children with an experience of homelessness to foster their social development.

  10. Testing the Species pool hypothesis for mire vegetation: exploring the influence of pH specialists and habitat history

    Czech Academy of Sciences Publication Activity Database

    Hájek, Michal; Tichý, L.; Schamp, B. S.; Zelený, D.; Roleček, J.; Hájková, Petra; Apostolova, I.; Dítě, D.

    2007-01-01

    Roč. 116, č. 8 (2007), s. 1311-1322 ISSN 0030-1299 R&D Projects: GA AV ČR IAA6163303 Grant - others:GA AV ČR(CZ) KJB6163302 Institutional research plan: CEZ:AV0Z60050516 Keywords : evolutionary species pool hypothesis * mire * pH Subject RIV: EF - Botanics Impact factor: 3.136, year: 2007

  11. Output, money, and the terms of trade in Germany: An empirical test of the real business cycle hypothesis

    OpenAIRE

    Scheide, Joachim

    1993-01-01

    The theory of real business cycles (RBC) interprets the often found link between money and output as one of reversed causality: A broad monetary aggregate such as Ml Granger-causes output only because of the response of endogenous money to changes in the production possibilities in the economy while exogenous money is neutral. Quarterly data for the period 1964 - 1989 are used to investigate the validity of the RBC hypothesis for Germany. On the basis of variance decomposition results for var...

  12. Testing the Sensory Drive Hypothesis: Geographic variation in echolocation frequencies of Geoffroy's horseshoe bat (Rhinolophidae: Rhinolophus clivosus)

    OpenAIRE

    Jacobs, David S.; Catto, Sarah; Mutumi, Gregory L.; Finger, Nikita; Webala, Paul W.

    2017-01-01

    Geographic variation in sensory traits is usually influenced by adaptive processes because these traits are involved in crucial life-history aspects including orientation, communication, lineage recognition and mate choice. Studying this variation can therefore provide insights into lineage diversification. According to the Sensory Drive Hypothesis, lineage diversification may be driven by adaptation of sensory systems to local environments. It predicts that acoustic signals vary in associati...

  13. Fine motor skills enhance lexical processing of embodied vocabulary: A test of the nimble-hands, nimble-minds hypothesis.

    Science.gov (United States)

    Suggate, Sebastian; Stoeger, Heidrun

    2017-10-01

    Research suggests that fine motor skills (FMS) are linked to aspects of cognitive development in children. Additionally, lexical processing advantages exist for words implying a high body-object interaction (BOI), with initial findings indicating that such words in turn link to children's FMS-for which we propose and evaluate four competing hypotheses. First, a maturational account argues that any links between FMS and lexical processing should not exist once developmental variables are controlled for. Second, functionalism posits that any link between FMS and lexical processing arises due to environmental interactions. Third, the semantic richness hypothesis argues that sensorimotor input improves lexical processing, but predicts no links between FMS and lexical processing. A fourth account, the nimble-hands, nimble minds (NHNM) hypothesis, proposes that having greater FMS improves lexical processing for high-BOI words. In two experiments, the response latencies of preschool children (n = 90, n = 76, ages = 5;1) to 45 lexical items encompassing high-BOI, low-BOI, and less imageable words were measured, alongside measures of FMS, reasoning, and general receptive/expressive vocabulary. High-BOI words appeared to show unique links to FMS, which remained after accounting for low-BOI and less imageable words, general vocabulary, reasoning, and chronological age. Although further work is needed, the findings provide initial support for the NHNM hypothesis.

  14. Sex Differences in Mobility and Spatial Cognition: A Test of the Fertility and Parental Care Hypothesis in Northwestern Namibia.

    Science.gov (United States)

    Vashro, Layne; Padilla, Lace; Cashdan, Elizabeth

    2016-03-01

    The fertility and parental care hypothesis interprets sex differences in some spatial-cognitive tasks as an adaptive mechanism to suppress women's travel. In particular, the hypothesis argues that estrogens constrain travel during key reproductive periods by depressing women's spatial-cognitive ability. Limiting travel reduces exposure to the dangers and caloric costs of navigating long distances into unfamiliar environments. Our study evaluates a collection of predictions drawn from the fertility and parental care hypothesis among the Twe and Himba people living in a remote region of Namibia. We find that nursing mothers travel more than women at any other stage of their reproductive career. This challenges the assumption that women limit travel during vulnerable and energetically demanding reproductive periods. In addition, we join previous studies in identifying a relationship between spatial ability and traveling among men, but not women. If spatial ability does not influence travel, hormonally induced changes in spatial ability cannot be used as a mechanism to reduce travel. Instead, it appears the fitness consequences of men's travel is a more likely target for adaptive explanations of the sex differences in spatial ability, navigation, and range size.

  15. Socioeconomic inequality in health in the British household panel: Tests of the social causation, health selection and the indirect selection hypothesis using dynamic fixed effects panel models.

    Science.gov (United States)

    Foverskov, Else; Holm, Anders

    2016-02-01

    Despite social inequality in health being well documented, it is still debated which causal mechanism best explains the negative association between socioeconomic position (SEP) and health. This paper is concerned with testing the explanatory power of three widely proposed causal explanations for social inequality in health in adulthood: the social causation hypothesis (SEP determines health), the health selection hypothesis (health determines SEP) and the indirect selection hypothesis (no causal relationship). We employ dynamic data of respondents aged 30 to 60 from the last nine waves of the British Household Panel Survey. Household income and location on the Cambridge Scale is included as measures of different dimensions of SEP and health is measured as a latent factor score. The causal hypotheses are tested using a time-based Granger approach by estimating dynamic fixed effects panel regression models following the method suggested by Anderson and Hsiao. We propose using this method to estimate the associations over time since it allows one to control for all unobserved time-invariant factors and hence lower the chances of biased estimates due to unobserved heterogeneity. The results showed no proof of the social causation hypothesis over a one to five year period and limited support for the health selection hypothesis was seen only for men in relation to HH income. These findings were robust in multiple sensitivity analysis. We conclude that the indirect selection hypothesis may be the most important in explaining social inequality in health in adulthood, indicating that the well-known cross-sectional correlations between health and SEP in adulthood seem not to be driven by a causal relationship, but instead by dynamics and influences in place before the respondents turn 30 years old that affect both their health and SEP onwards. The conclusion is limited in that we do not consider the effect of specific diseases and causal relationships in adulthood may be

  16. The relationship between motor proficiency and mental health outcomes in young adults: A test of the Environmental Stress Hypothesis.

    Science.gov (United States)

    Rigoli, D; Kane, R T; Mancini, V; Thornton, A; Licari, M; Hands, B; McIntyre, F; Piek, J

    2017-06-01

    Growing evidence has highlighted the importance of motor proficiency in relation to psychosocial outcomes including self-perceived competence in various domains, perceived social support, and emotional areas such as anxiety and depression. The Environmental Stress Hypothesis-elaborated (Cairney, Rigoli, & Piek, 2013) is a proposed theoretical framework for understanding these relationships and recent studies have begun examining parts of this model using child and adolescent populations. However, the extent to which the relationships between these areas exist, persist or change during early adulthood is currently unclear. The current study aimed to investigate the Environmental Stress Hypothesis in a sample of 95 young adults aged 18-30years and examined the mediating role of physical self-worth and perceived social support in the relationship between motor proficiency and internalising symptoms. The McCarron Assessment of Neuromuscular Development (McCarron, 1997) was used to assess motor proficiency, the Depression Anxiety Stress Scale (Lovibond & Lovibond, 1995) provided a measure of internalising symptoms, and the Physical Self Perceptions Profile (Fox & Corbin, 1989) and the Multidimensional Scale of Perceived Social Support (Zimet, Dahlem, Zimet, & Farley, 1988) were used to investigate the possible mediating role of physical self-worth and perceived social support respectively. Potential confounding variables such as age, gender and BMI were also considered in the analysis. Structural Equation Modelling revealed that perceived social support mediated the relationship between motor proficiency and internalising symptoms, whereas, the mediating role of physical self-worth was non-significant. The current results provide support for part of the model pathways as described in the Environmental Stress Hypothesis and suggest an important relationship between motor proficiency and psychosocial outcomes in young adults. Specifically, the results support previous

  17. Brain-Derived Neurotrophic Factor Expression in Individuals With Schizophrenia and Healthy Aging: Testing the Accelerated Aging Hypothesis of Schizophrenia.

    Science.gov (United States)

    Islam, Farhana; Mulsant, Benoit H; Voineskos, Aristotle N; Rajji, Tarek K

    2017-07-01

    Schizophrenia has been hypothesized to be a syndrome of accelerated aging. Brain plasticity is vulnerable to the normal aging process and affected in schizophrenia: brain-derived neurotrophic factor (BDNF) is an important neuroplasticity molecule. The present review explores the accelerated aging hypothesis of schizophrenia by comparing changes in BDNF expression in schizophrenia with aging-associated changes. Individuals with schizophrenia show patterns of increased overall mortality, metabolic abnormalities, and cognitive decline normally observed later in life in the healthy population. An overall decrease is observed in BDNF expression in schizophrenia compared to healthy controls and in older individuals compared to a younger cohort. There is a marked decrease in BDNF levels in the frontal regions and in the periphery among older individuals and those with schizophrenia; however, data for BDNF expression in the occipital, parietal, and temporal cortices and the hippocampus is inconclusive. Accelerated aging hypothesis is supported based on frontal regions and peripheral studies; however, further studies are needed in other brain regions.

  18. Project of the experiment to test the hypothesis on existence of 'white' and 'black' pμ-atoms

    International Nuclear Information System (INIS)

    Brudanin, V.B.; Bystritskij, V.M.; Wawryscuk, J.

    1992-01-01

    This article is dedicated to the analysis of the experiment on the investigation of the muon trasfer from pμ-atom to oxygen and sulphur nuclei in the H 2 +0,4%SO 2 mixture performed to Swiss group on the meson factory PSI. The conclusion of the authors of the considered article about existence of the different types of pμ-atoms ('coloured') because they didn't take into account a number of the accompanying physical processes which imitate the observed effect have doubt. With the purpose of the checking the hypothesis of the existence of 'coloured' pμ-atoms the experiment in which the influence of the accompanying processes is minimal is proposed. 15 refs.; 1 fig

  19. Hypothesis testing clarifies the systematics of the main Central American Chagas disease vector, Triatoma dimidiata (Latreille, 1811), across its geographic range.

    Science.gov (United States)

    Dorn, Patricia L; de la Rúa, Nicholas M; Axen, Heather; Smith, Nicholas; Richards, Bethany R; Charabati, Jirias; Suarez, Julianne; Woods, Adrienne; Pessoa, Rafaela; Monroy, Carlota; Kilpatrick, C William; Stevens, Lori

    2016-10-01

    The widespread and diverse Triatoma dimidiata is the kissing bug species most important for Chagas disease transmission in Central America and a secondary vector in Mexico and northern South America. Its diversity may contribute to different Chagas disease prevalence in different localities and has led to conflicting systematic hypotheses describing various populations as subspecies or cryptic species. To resolve these conflicting hypotheses, we sequenced a nuclear (internal transcribed spacer 2, ITS-2) and mitochondrial gene (cytochrome b) from an extensive sampling of T. dimidiata across its geographic range. We evaluated the congruence of ITS-2 and cyt b phylogenies and tested the support for the previously proposed subspecies (inferred from ITS-2) by: (1) overlaying the ITS-2 subspecies assignments on a cyt b tree and, (2) assessing the statistical support for a cyt b topology constrained by the subspecies hypothesis. Unconstrained phylogenies inferred from ITS-2 and cyt b are congruent and reveal three clades including two putative cryptic species in addition to T. dimidiata sensu stricto. Neither the cyt b phylogeny nor hypothesis testing support the proposed subspecies inferred from ITS-2. Additionally, the two cryptic species are supported by phylogenies inferred from mitochondrially-encoded genes cytochrome c oxidase I and NADH dehydrogenase 4. In summary, our results reveal two cryptic species. Phylogenetic relationships indicate T. dimidiata sensu stricto is not subdivided into monophyletic clades consistent with subspecies. Based on increased support by hypothesis testing, we propose an updated systematic hypothesis for T. dimidiata based on extensive taxon sampling and analysis of both mitochondrial and nuclear genes. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Effects of musicality and motivational orientation on auditory category learning: a test of a regulatory-fit hypothesis.

    Science.gov (United States)

    McAuley, J Devin; Henry, Molly J; Wedd, Alan; Pleskac, Timothy J; Cesario, Joseph

    2012-02-01

    Two experiments investigated the effects of musicality and motivational orientation on auditory category learning. In both experiments, participants learned to classify tone stimuli that varied in frequency and duration according to an initially unknown disjunctive rule; feedback involved gaining points for correct responses (a gains reward structure) or losing points for incorrect responses (a losses reward structure). For Experiment 1, participants were told at the start that musicians typically outperform nonmusicians on the task, and then they were asked to identify themselves as either a "musician" or a "nonmusician." For Experiment 2, participants were given either a promotion focus prime (a performance-based opportunity to gain entry into a raffle) or a prevention focus prime (a performance-based criterion that needed to be maintained to avoid losing an entry into a raffle) at the start of the experiment. Consistent with a regulatory-fit hypothesis, self-identified musicians and promotion-primed participants given a gains reward structure made more correct tone classifications and were more likely to discover the optimal disjunctive rule than were musicians and promotion-primed participants experiencing losses. Reward structure (gains vs. losses) had inconsistent effects on the performance of nonmusicians, and a weaker regulatory-fit effect was found for the prevention focus prime. Overall, the findings from this study demonstrate a regulatory-fit effect in the domain of auditory category learning and show that motivational orientation may contribute to musician performance advantages in auditory perception.

  1. Trappings of femininity: A test of the "beauty as currency" hypothesis in shaping college women's gender activism.

    Science.gov (United States)

    Calogero, Rachel M; Tylka, Tracy L; Donnelly, Lois C; McGetrick, Amber; Leger, Andrea Medrano

    2017-06-01

    This study investigated whether believing beauty is a primary currency for women operates as an antecedent force in the relation between self-objectification and gender activism. Ninety-four ethnically diverse women attending a small liberal arts college in the southeastern United States completed the study questionnaires online for course credit. Preliminary results demonstrated beauty as currency belief, self-objectification, and support for the gender status quo were negatively associated with gender activism. A serial mediation analysis revealed support for the proposed model: Beauty as currency belief was indirectly and inversely linked to gender activism through self-objectification and support for the gender status quo, offering initial evidence for our beauty as currency hypothesis. These findings suggest belief in the notion women will reap more benefits from their bodies than other attributes or pursuits may be an important legitimizing feature of feminine beauty ideology that works through self-objectification against gender social change. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Maternal play behaviors, child negativity, and preterm or low birthweight toddlers' visual-spatial outcomes: testing a differential susceptibility hypothesis.

    Science.gov (United States)

    Dilworth-Bart, Janean E; Miller, Kyle E; Hane, Amanda

    2012-04-01

    We examined the joint roles of child negative emotionality and parenting in the visual-spatial development of toddlers born preterm or with low birthweights (PTLBW). Neonatal risk data were collected at hospital discharge, observer- and parent-rated child negative emotionality was assessed at 9-months postterm, and mother-initiated task changes and flexibility during play were observed during a dyadic play interaction at 16-months postterm. Abbreviated IQ scores, and verbal/nonverbal and visual-spatial processing data were collected at 24-months postterm. Hierarchical regression analyses did not support our hypothesis that the visual-spatial processing of PTLBW toddlers with higher negative emotionality would be differentially susceptible to parenting behaviors during play. Instead, observer-rated distress and a negativity composite score were associated with less optimal visual-spatial processing when mothers were more flexible during the 16-month play interaction. Mother-initiated task changes did not interact with any of the negative emotionality variables to predict any of the 24-month neurocognitive outcomes, nor did maternal flexibility interact with mother-rated difficult temperament to predict the visual-spatial processing outcomes. Copyright © 2011 Elsevier Inc. All rights reserved.

  3. Maternal play behaviors, child negativity, and preterm or low birthweight toddlers’ visual-spatial outcomes: Testing a differential susceptibility hypothesis

    Science.gov (United States)

    Dilworth-Bart, Janean E.; Miller, Kyle E.; Hane, Amanda

    2012-01-01

    Objective We examined the joint roles of child negative emotionality and parenting in the visual-spatial development of toddlers born preterm or with low birthweights (PTLBW). Method Neonatal risk data were collected at hospital discharge, observer- and parent-rated child negative emotionality was assessed at 9-months postterm, and mother-initiated task changes and flexibility during play were observed during a dyadic play interaction at 16-months postterm. Abbreviated IQ scores, and verbal/nonverbal and visual-spatial processing data were collected at 24-months postterm. Results Hierarchical regression analyses did not support our hypothesis that the visual-spatial processing of PTLBW toddlers with higher negative emotionality would be differentially susceptible to parenting behaviors during play. Instead, observer-rated distress and a negativity composite score were associated with less optimal visual-spatial processing when mothers were more flexible during the 16-month play interaction. Mother-initiated task changes did not interact with any of the negative emotionality variables to predict any of the 24-month neurocognitive outcomes, nor did maternal flexibility interact with mother-rated difficult temperament to predict the visual-spatial processing outcomes. PMID:22209050

  4. Is low IQ related to risk of death by homicide? Testing an hypothesis using data from a longitudinal study

    DEFF Research Database (Denmark)

    Batty, George David; Mortensen, Laust Hvas; Gale, Catharine R

    2008-01-01

    Lower IQ test scores are related to an increased risk of violent assault. We tested the relation between IQ and death by homicide. In a prospective cohort study of 14,537 men (21 homicides), the association between lower IQ and an increased risk of homicide was lost after multiple adjustment....

  5. [Biologic tests for the diagnosis of amniotic fluid embolism].

    Science.gov (United States)

    Van Cortenbosch, B; Huel, C; Houfflin Debarge, V; Luton, D; Lambaudie, E; Porquet, D; Guibourdenche, J

    2007-01-01

    Amniotic fluid embolism is a rare, unpredictable and often lethal complication of pregnancy and childbirth. Because of its variable presentation, an early biologic test would help to establish the diagnosis. We investigated in maternal serum 4 components of amniotic fluid, i.e., alpha-fetoprotein (AFP), l'insuline like growth factor binding protein-1 (IGFBP-1), fetal fibronectin (fFN) and placental alpha1-microglobulin (PAMG-1). On the 6 cesareans controls involved, none of the makers increased after membranes section. PAMG-1 is unsuitable because its detection is always positive or doubtful even in the baseline. On the 7 cases suspected of amniotic fluid embolism, no detectable increase in any of those markers was noted in 3 cases, which is not in favour of this diagnosis. In the remaining cases, IGFBP-1 and fFN became detectable, confirming histological evidences of amniotic fluid embolism in 2 cases. The follow up of those markers in maternal blood confirmed the suspicion of amniotic fluid embolism at 21 wg in one case of ongoing pregnancy. These preliminary results point out the potential interest to assay maternal serum AFP, IGFBP-1 and fFN to confirm amniotic fluid embolism using rapid laboratory tests.

  6. Biomic specialization and speciation rates in ruminants (Cetartiodactyla, Mammalia): a test of the resource-use hypothesis at the global scale.

    Science.gov (United States)

    Cantalapiedra, Juan L; Hernández Fernández, Manuel; Morales, Jorge

    2011-01-01

    The resource-use hypothesis proposed by E.S. Vrba predicts that specialist species have higher speciation and extinction rates than generalists because they are more susceptible to environmental changes and vicariance. In this work, we test some of the predictions derived from this hypothesis on the 197 extant and recently extinct species of Ruminantia (Cetartiodactyla, Mammalia) using the biomic specialization index (BSI) of each species, which is based on its distribution within different biomes. We ran 10000 Monte Carlo simulations of our data in order to get a null distribution of BSI values against which to contrast the observed data. Additionally, we drew on a supertree of the ruminants and a phylogenetic likelihood-based method (QuaSSE) for testing whether the degree of biomic specialization affects speciation rates in ruminant lineages. Our results are consistent with the predictions of the resource-use hypothesis, which foretells a higher speciation rate of lineages restricted to a single biome (BSI = 1) and higher frequency of specialist species in biomes that underwent high degree of contraction and fragmentation during climatic cycles. Bovids and deer present differential specialization across biomes; cervids show higher specialization in biomes with a marked hydric seasonality (tropical deciduous woodlands and schlerophyllous woodlands), while bovids present higher specialization in a greater variety of biomes. This might be the result of divergent physiological constraints as well as a different biogeographic and evolutionary history.

  7. Testing the hypothesis that biological modularity is shaped by adaptation: Xylem in the Bursera simaruba clade of tropical trees.

    Science.gov (United States)

    Gabriela Montes-Cartas, Claudia; Padilla, Pablo; Rosell, Julieta A; Domínguez, César A; Fornoni, Juan; Olson, Mark E

    2017-05-01

    The study of modularity allows recognition of suites of character covariation that potentially diagnose units of evolutionary change. One prominent perspective predicts that natural selection should forge developmental units that maximize mutual functional independence. We examined the module-function relation using secondary xylem (wood) in a clade of tropical trees as a study system. Traditionally, the three main cell types in wood (vessels, fibers, and parenchyma) have respectively been associated with three functions (conduction, mechanical support, and storage). We collected samples from nine species of the simaruba clade of Bursera at fifteen sites and measured thirteen anatomical variables that have traditionally been regarded as reflecting the distinct functions of these cell types. If there are indeed (semi) independently evolving modules associated with functions, and cell types really are associated with these functions, then we should observe greater association between traits within cell types than between traits from different cell types. To map these associations, we calculated correlation coefficients among anatomical variables and identified modules using cluster and factor analysis. Our results were only partially congruent with expectations, with associations between characters of different cell types common. These results suggest causes of covariation, some involving selected function as predicted, but also highlighting the tradeoffs and shared developmental pathways limiting the evolutionary independence of some cell types in the secondary xylem. The evolution of diversity across the simaruba clade appears to have required only limited independence between parts. © 2017 Wiley Periodicals, Inc.

  8. Catechol-O-methyltransferase Val158 Met genotype, parenting practices and adolescent alcohol use: testing the differential susceptibility hypothesis.

    Science.gov (United States)

    Laucht, Manfred; Blomeyer, Dorothea; Buchmann, Arlette F; Treutlein, Jens; Schmidt, Martin H; Esser, Günter; Jennen-Steinmetz, Christine; Rietschel, Marcella; Zimmermann, Ulrich S; Banaschewski, Tobias

    2012-04-01

      Recently, first evidence has been reported for a gene-parenting interaction (G × E) with regard to adolescent alcohol use. The present investigation set out to extend this research using the catechol-O-methyltransferase (COMT) Val(158) Met polymorphism as a genetic susceptibility factor. Moreover, the current study examined whether a potential G×E would be consistent with one of two models of gene-environment interplay (genetic vulnerability vs. differential susceptibility).   Data were collected as part of an ongoing epidemiological cohort study following the outcome of early risk factors from birth into adulthood. Two hundred and eighty-five participants (130 males, 155 females) were genotyped for the COMT Val(158) Met polymorphism and were administered an alcohol interview, providing measures of current frequency and amount of drinking at ages 15 and 19 years. Information on three dimensions of perceived parenting behavior was obtained from the 15-year-olds.   Adolescents homozygous for the Met allele showed higher drinking activity at age 19 years when their parents had engaged in less supervision or were less involved, while their drinking activity was reduced under conditions of favorable parenting. No such relationship was found in individuals carrying the Val allele.   The present findings correspond with the pattern of results predicted by the differential susceptibility hypothesis, suggesting that environmental variation would have a greater impact in individuals carrying a genetic susceptibility such that, in this group, exposure to negative environmental conditions would result in more adverse outcomes and the experience of favorable conditions would lead to more positive outcomes. © 2011 The Authors. Journal of Child Psychology and Psychiatry © 2011 Association for Child and Adolescent Mental Health.

  9. The relationship between motor skills and psychosocial factors in young children: A test of the elaborated environmental stress hypothesis.

    Science.gov (United States)

    Mancini, Vincent O; Rigoli, Daniela; Roberts, Lynne D; Heritage, Brody; Piek, Jan P

    2017-09-08

    The elaborated environmental stress hypothesis (EESH) provides a framework that describes how motor skills may indirectly cause internalizing problems through various mediating psychosocial factors. While there is evidence to support this framework, little is known about how the proposed relationships may vary across different stages of development. This study aimed to investigate whether peer problems and perceived self-competence mediated the relationship between motor skills and internalizing problems in pre-primary children, and at 18-month follow up. A community sample of 197 pre-primary school children (M = 5.40 years, SD = 0.30 years; 102 males, 95 females) participated at Time 1, with 107 completing the Time 2 follow-up. Standardized instruments were used to measure motor skills and verbal IQ. Perceived self-competence was measured using a self-report measure. Participant peer problems and internalizing problems were measured using teacher report. Age, gender, and verbal IQ were included as covariates. Mediation analysis using PROCESS showed that the relationship between motor skills and internalizing problems was mediated by peer problems at Time 1. At Time 2, the relationship was mediated by peer problems and perceived physical competence. The current results indicate the EESH may function differently across different periods of development. The transition from pre-primary to Grade 1 represents a time of important cognitive and psychosocial development, which has implications for how the relationship between motor skills and internalizing problems can be understood. These findings highlight potential age-appropriate targets for psychomotor interventions aiming to improve the emotional well-being of young children. © 2017 The British Psychological Society.

  10. Duration of residence and disease occurrence among refugees and family reunited immigrants: test of the 'healthy migrant effect' hypothesis.

    Science.gov (United States)

    Norredam, Marie; Agyemang, Charles; Hoejbjerg Hansen, Oluf K; Petersen, Jørgen H; Byberg, Stine; Krasnik, Allan; Kunst, Anton E

    2014-08-01

    The 'healthy migrant effect' (HME) hypothesis postulates that health selection has a positive effect on migrants' health outcomes, especially in the first years after migration. We examined the potential role of the HME by assessing the association between residence duration and disease occurrence. We performed a historical prospective cohort study. We included migrants who obtained residence permits in Denmark between 1 January 1993 and 31 December 2010 (n = 114,331). Occurrence of severe conditions was identified through linkage to the Danish National Patient Register. Hazard Ratios (HRs) were modelled for disease incidence by residence duration since arrival (0-5 years; 0-10 years; 0-18 years) adjusting for age and sex. Compared with Danish-born individuals, refugees and family reunited immigrants had lower HRs of stroke and breast cancer within 5 years after arrival; however, HRs increased at longer follow-up. For example, HRs of stroke among refugees increased from 0.77 (95% CI: 0.66; 0.91) to 0.96 (95% CI: 0.88; 1.05). For ischaemic heart disease (IHD) and diabetes, refugees and family reunited migrants had higher HRs within 5 years after arrival, and most HRs had increased by end of follow-up. For example, HRs of IHD among family reunited migrants increased from 1.29 (95% CI: 1.17; 1.42) to 1.43 (95% CI: 1.39; 1.52). In contrast, HRs for TB and HIV/AIDS showed a consistent decrease over time. Our analyses of the effect of duration of residence on disease occurrence among migrants imply that, when explaining migrants' advantageous health outcomes, the ruling theory of the HME should be used with caution, and other explanatory models should be included. © 2014 John Wiley & Sons Ltd.

  11. Properties of hypothesis testing techniques and (Bayesian) model selection for exploration-based and theory-based (order-restricted) hypotheses.

    Science.gov (United States)

    Kuiper, Rebecca M; Nederhoff, Tim; Klugkist, Irene

    2015-05-01

    In this paper, the performance of six types of techniques for comparisons of means is examined. These six emerge from the distinction between the method employed (hypothesis testing, model selection using information criteria, or Bayesian model selection) and the set of hypotheses that is investigated (a classical, exploration-based set of hypotheses containing equality constraints on the means, or a theory-based limited set of hypotheses with equality and/or order restrictions). A simulation study is conducted to examine the performance of these techniques. We demonstrate that, if one has specific, a priori specified hypotheses, confirmation (i.e., investigating theory-based hypotheses) has advantages over exploration (i.e., examining all possible equality-constrained hypotheses). Furthermore, examining reasonable order-restricted hypotheses has more power to detect the true effect/non-null hypothesis than evaluating only equality restrictions. Additionally, when investigating more than one theory-based hypothesis, model selection is preferred over hypothesis testing. Because of the first two results, we further examine the techniques that are able to evaluate order restrictions in a confirmatory fashion by examining their performance when the homogeneity of variance assumption is violated. Results show that the techniques are robust to heterogeneity when the sample sizes are equal. When the sample sizes are unequal, the performance is affected by heterogeneity. The size and direction of the deviations from the baseline, where there is no heterogeneity, depend on the effect size (of the means) and on the trend in the group variances with respect to the ordering of the group sizes. Importantly, the deviations are less pronounced when the group variances and sizes exhibit the same trend (e.g., are both increasing with group number). © 2014 The British Psychological Society.

  12. Do larval types affect genetic connectivity at sea? Testing hypothesis in two sibling marine gastropods with contrasting larval development.

    Science.gov (United States)

    Modica, Maria Vittoria; Russini, Valeria; Fassio, Giulia; Oliverio, Marco

    2017-06-01

    their genetic variation showed patterns supporting the hypothesis that PLD is a major factor affecting genetic connectivity. Therefore, it seems reasonable to expect that the ecological attributes of the marine communities - also in terms of the variation in larval ecology of the species involved - are taken into the due consideration in conservation actions, like the design of marine protected areas networks. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Testing the shape-similarity hypothesis between particle-size distribution and water retention for Sicilian soils

    Directory of Open Access Journals (Sweden)

    Chiara Antinoro

    2012-12-01

    Full Text Available Application of the Arya and Paris (AP model to estimate the soil water retention curve requires a detailed description of the particlesize distribution (PSD but limited experimental PSD data are generally determined by the conventional sieve-hydrometer (SH method. Detailed PSDs can be obtained by fitting a continuous model to SH data or performing measurements by the laser diffraction (LD method. The AP model was applied to 40 Sicilian soils for which the PSD was measured by both the SH and LD methods. The scale factor was set equal to 1.38 (procedure AP1 or estimated by a logistical model with parameters gathered from literature (procedure AP2. For both SH and LD data, procedure AP2 allowed a more accurate prediction of the water retention than procedure AP1, confirming that it is not convenient to use a unique value of  for soils that are very different in texture. Despite the differences in PSDs obtained by the SH and LD methods, the water retention predicted by a given procedure (AP1 or AP2 using SH or LD data was characterized by the same level of accuracy. Discrepancies in the estimated water retention from the two PSD measurement methods were attributed to underestimation of the finest diameter frequency obtained by the LD method. Analysis also showed that the soil water retention estimated using the SH method was affected by an estimation bias that could be corrected by an optimization procedure (OPT. Comparison of a-distributions and water retention shape indices obtained by the two methods (SH or LD indicated that the shape-similarity hypothesis is better verified if the traditional sieve-hydrometer data are used to apply the AP model. The optimization procedure allowed more accurate predictions of the water retention curves than the traditional AP1 and AP2 procedures. Therefore, OPT can be considered a valid alternative to the more complex logistical model for estimating the water retention curve of Sicilian soils.

  14. Ostracoda (Arthropoda, Crustacea) in a Miocene oxygen minimum zone, Trinidad, West Indies: A test of the Platycopid Signal Hypothesis

    Science.gov (United States)

    Wilson, Brent; Coimbra, João C.; Hayek, Lee-Ann C.

    2014-10-01

    Studies of Recent ostracodes around the area of South America shed little light on the paleoenvironmental interpretation of Miocene assemblages. Consequently, interpretations of the Miocene ostracode assemblages must be supplemented using evidence from better documented taxa. Benthic foraminifera in samples from the Lower to Middle Miocene Brasso Formation at Brasso Village, Trinidad, have previously been used to distinguish three sample groupings (Beneath, Within and Above) around an oxygen minimum zone (OMZ), this being a layer of water within which dissolved oxygen concentrations can be as low as 0.1-1.0 mL/L. Using these same samples and the foraminiferal assemblage demarcations relative to the OMZ, this paper examines the associated and rich ostracode fauna of the Brasso Formation. The mean recovery of ostracode valves per sample was approximately three times greater in the Within OMZ sample group than in either of the Beneath OMZ or Above OMZ groups, perhaps reflecting the exclusion of macro-predators from within the OMZ. Individual rarefaction of species richness S to N = 300 valves was conducted for each sample group. This showed that S did not differ between the sample groups, ranging from 22.4 to 24.8. We used all ostracode species to model group separation. Based upon the Mahalanobis' criterion, we obtained significant group separation using a model with four taxa: Munseyella ex gr. minuta, Argilloecia posterotruncata, Munseyella sp. and Xestoleberis sp., while a fifth, Argilloecia spp., provided a significant but minor increase in separation probabilities over all groups. The two most abundant species (Bradleya sp., Gangamocytheridea reticulata) were thus not the best species for detecting the OMZ. Platycopid ostracodes of the genus Cytherella were found throughout the section, rather than concentrated within the OMZ, which contradicts the Platycopid Signal Hypothesis that OMZs are characterized by platycopid dominance. The total distribution and

  15. Statistical Hypothesis Testing using CNN Features for Synthesis of Adversarial Counterexamples to Human and Object Detection Vision Systems

    Energy Technology Data Exchange (ETDEWEB)

    Raj, Sunny [Univ. of Central Florida, Orlando, FL (United States); Jha, Sumit Kumar [Univ. of Central Florida, Orlando, FL (United States); Pullum, Laura L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ramanathan, Arvind [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-05-01

    Validating the correctness of human detection vision systems is crucial for safety applications such as pedestrian collision avoidance in autonomous vehicles. The enormous space of possible inputs to such an intelligent system makes it difficult to design test cases for such systems. In this report, we present our tool MAYA that uses an error model derived from a convolutional neural network (CNN) to explore the space of images similar to a given input image, and then tests the correctness of a given human or object detection system on such perturbed images. We demonstrate the capability of our tool on the pre-trained Histogram-of-Oriented-Gradients (HOG) human detection algorithm implemented in the popular OpenCV toolset and the Caffe object detection system pre-trained on the ImageNet benchmark. Our tool may serve as a testing resource for the designers of intelligent human and object detection systems.

  16. Detecting seasonal and cyclical trends in agricultural runoff water quality-hypothesis tests and block bootstrap power analysis.

    Science.gov (United States)

    Uddameri, Venkatesh; Singaraju, Sreeram; Hernandez, E Annette

    2018-02-21

    Seasonal and cyclic trends in nutrient concentrations at four agricultural drainage ditches were assessed using a dataset generated from a multivariate, multiscale, multiyear water quality monitoring effort in the agriculturally dominant Lower Rio Grande Valley (LRGV) River Watershed in South Texas. An innovative bootstrap sampling-based power analysis procedure was developed to evaluate the ability of Mann-Whitney and Noether tests to discern trends and to guide future monitoring efforts. The Mann-Whitney U test was able to detect significant changes between summer and winter nutrient concentrations at sites with lower depths and unimpeded flows. Pollutant dilution, non-agricultural loadings, and in-channel flow structures (weirs) masked the effects of seasonality. The detection of cyclical trends using the Noether test was highest in the presence of vegetation mainly for total phosphorus and oxidized nitrogen (nitrite + nitrate) compared to dissolved phosphorus and reduced nitrogen (total Kjeldahl nitrogen-TKN). Prospective power analysis indicated that while increased monitoring can lead to higher statistical power, the effect size (i.e., the total number of trend sequences within a time-series) had a greater influence on the Noether test. Both Mann-Whitney and Noether tests provide complementary information on seasonal and cyclic behavior of pollutant concentrations and are affected by different processes. The results from these statistical tests when evaluated in the context of flow, vegetation, and in-channel hydraulic alterations can help guide future data collection and monitoring efforts. The study highlights the need for long-term monitoring of agricultural drainage ditches to properly discern seasonal and cyclical trends.

  17. A Test of the Circumvention-of-Limits Hypothesis in Scientific Problem Solving: The Case of Geological Bedrock Mapping

    Science.gov (United States)

    Hambrick, David Z.; Libarkin, Julie C.; Petcovic, Heather L.; Baker, Kathleen M.; Elkins, Joe; Callahan, Caitlin N.; Turner, Sheldon P.; Rench, Tara A.; LaDue, Nicole D.

    2012-01-01

    Sources of individual differences in scientific problem solving were investigated. Participants representing a wide range of experience in geology completed tests of visuospatial ability and geological knowledge, and performed a geological bedrock mapping task, in which they attempted to infer the geological structure of an area in the Tobacco…

  18. Warriors and peacekeepers: testing a biosocial implicit leadership hypothesis of intergroup relations using masculine and feminine faces.

    Science.gov (United States)

    Spisak, Brian R; Dekker, Peter H; Krüger, Max; van Vugt, Mark

    2012-01-01

    This paper examines the impact of facial cues on leadership emergence. Using evolutionary social psychology, we expand upon implicit and contingent theories of leadership and propose that different types of intergroup relations elicit different implicit cognitive leadership prototypes. It is argued that a biologically based hormonal connection between behavior and corresponding facial characteristics interacts with evolutionarily consistent social dynamics to influence leadership emergence. We predict that masculine-looking leaders are selected during intergroup conflict (war) and feminine-looking leaders during intergroup cooperation (peace). Across two experiments we show that a general categorization of leader versus nonleader is an initial implicit requirement for emergence, and at a context-specific level facial cues of masculinity and femininity contingently affect war versus peace leadership emergence in the predicted direction. In addition, we replicate our findings in Experiment 1 across culture using Western and East Asian samples. In Experiment 2, we also show that masculine-feminine facial cues are better predictors of leadership than male-female cues. Collectively, our results indicate a multi-level classification of context-specific leadership based on visual cues imbedded in the human face and challenge traditional distinctions of male and female leadership.

  19. Warriors and peacekeepers: testing a biosocial implicit leadership hypothesis of intergroup relations using masculine and feminine faces.

    Directory of Open Access Journals (Sweden)

    Brian R Spisak

    Full Text Available This paper examines the impact of facial cues on leadership emergence. Using evolutionary social psychology, we expand upon implicit and contingent theories of leadership and propose that different types of intergroup relations elicit different implicit cognitive leadership prototypes. It is argued that a biologically based hormonal connection between behavior and corresponding facial characteristics interacts with evolutionarily consistent social dynamics to influence leadership emergence. We predict that masculine-looking leaders are selected during intergroup conflict (war and feminine-looking leaders during intergroup cooperation (peace. Across two experiments we show that a general categorization of leader versus nonleader is an initial implicit requirement for emergence, and at a context-specific level facial cues of masculinity and femininity contingently affect war versus peace leadership emergence in the predicted direction. In addition, we replicate our findings in Experiment 1 across culture using Western and East Asian samples. In Experiment 2, we also show that masculine-feminine facial cues are better predictors of leadership than male-female cues. Collectively, our results indicate a multi-level classification of context-specific leadership based on visual cues imbedded in the human face and challenge traditional distinctions of male and female leadership.

  20. Warriors and Peacekeepers: Testing a Biosocial Implicit Leadership Hypothesis of Intergroup Relations Using Masculine and Feminine Faces

    Science.gov (United States)

    Spisak, Brian R.; Dekker, Peter H.; Krüger, Max; van Vugt, Mark

    2012-01-01

    This paper examines the impact of facial cues on leadership emergence. Using evolutionary social psychology, we expand upon implicit and contingent theories of leadership and propose that different types of intergroup relations elicit different implicit cognitive leadership prototypes. It is argued that a biologically based hormonal connection between behavior and corresponding facial characteristics interacts with evolutionarily consistent social dynamics to influence leadership emergence. We predict that masculine-looking leaders are selected during intergroup conflict (war) and feminine-looking leaders during intergroup cooperation (peace). Across two experiments we show that a general categorization of leader versus nonleader is an initial implicit requirement for emergence, and at a context-specific level facial cues of masculinity and femininity contingently affect war versus peace leadership emergence in the predicted direction. In addition, we replicate our findings in Experiment 1 across culture using Western and East Asian samples. In Experiment 2, we also show that masculine-feminine facial cues are better predictors of leadership than male-female cues. Collectively, our results indicate a multi-level classification of context-specific leadership based on visual cues imbedded in the human face and challenge traditional distinctions of male and female leadership. PMID:22276190

  1. Racial/Ethnic Discrimination and Mental Health in Mexican-Origin Youths and Their Parents: Testing the "Linked Lives" Hypothesis.

    Science.gov (United States)

    Park, Irene J K; Du, Han; Wang, Lijuan; Williams, David R; Alegría, Margarita

    2018-04-01

    Using a life course perspective, the present study tested the concept of "linked lives" applied to the problem of not only how racial/ethnic discrimination may be associated with poor mental health for the target of discrimination but also how discrimination may exacerbate the discrimination-distress link for others in the target's social network-in this case, the family. The discrimination-distress link was investigated among 269 Mexican-origin adolescents and their parents both cross-sectionally and longitudinally. It was hypothesized that parents' discrimination experiences would adversely affect their adolescent children's mental health via a moderating effect on the target adolescent discrimination-distress link. The converse was also hypothesized for the target parents. Multilevel moderation analyses were conducted to test the moderating effect of parents' discrimination experiences on the youth discrimination-distress link. We also tested the moderating effect of youths' discrimination experiences on the parent discrimination-distress link. Parents' discrimination experiences significantly moderated the longitudinal association between youths' discrimination stress appraisals and mental health, such that the father's discrimination experiences exacerbated the youth discrimination-depression link. Youths' discrimination stress appraisals were not a significant moderator of the cross-sectional parent discrimination-mental health association. Implications of these findings are discussed from a linked lives perspective, highlighting how fathers' discrimination experiences can adversely affect youths who are coping with discrimination, in terms of their mental health. Copyright © 2017 The Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

  2. Testing the additive versus the compensatory hypothesis of mortality from ring recovery data using a random effects model

    Directory of Open Access Journals (Sweden)

    Schaub, M.

    2004-06-01

    Full Text Available The interaction of an additional source of mortality with the underlying “natural” one strongly affects population dynamics. We propose an alternative way to test between two forms of interaction, total additivity and compensation. In contrast to existing approaches, only ring-recovery data where the cause of death of each recovered individual is known are needed. Cause-specific mortality proportions are estimated based on a multistate capture-recapture model. The hypotheses are tested by inspecting the correlation between the cause-specific mortality proportions. A variance decomposition is performed to obtain a proper estimate of the true process correlation. The estimation of the cause-specific mortality proportions is the most critical part of the approach. It works well if at least one of the two mortality rates varies across time and the two recovery rates are constant across time. We illustrate this methodology by a case study of White Storks Ciconia ciconia where we tested whether mortality induced by power line collision is additive to other forms of mortality.

  3. Testing the snake-detection hypothesis: larger early posterior negativity in humans to pictures of snakes than to pictures of other reptiles, spiders and slugs.

    Science.gov (United States)

    Van Strien, Jan W; Franken, Ingmar H A; Huijding, Jorg

    2014-01-01

    According to the snake detection hypothesis (Isbell, 2006), fear specifically of snakes may have pushed evolutionary changes in the primate visual system allowing pre-attentional visual detection of fearful stimuli. A previous study demonstrated that snake pictures, when compared to spiders or bird pictures, draw more early attention as reflected by larger early posterior negativity (EPN). Here we report two studies that further tested the snake detection hypothesis. In Study 1, we tested whether the enlarged EPN is specific for snakes or also generalizes to other reptiles. Twenty-four healthy, non-phobic women watched the random rapid serial presentation of snake, crocodile, and turtle pictures. The EPN was scored as the mean activity at occipital electrodes (PO3, O1, Oz, PO4, O2) in the 225-300 ms time window after picture onset. The EPN was significantly larger for snake pictures than for pictures of the other reptiles. In Study 2, we tested whether disgust plays a role in the modulation of the EPN and whether preferential processing of snakes also can be found in men. 12 men and 12 women watched snake, spider, and slug pictures. Both men and women exhibited the largest EPN amplitudes to snake pictures, intermediate amplitudes to spider pictures and the smallest amplitudes to slug pictures. Disgust ratings were not associated with EPN amplitudes. The results replicate previous findings and suggest that ancestral priorities modulate the early capture of visual attention.

  4. Examining Rural-Urban Obesity Trends among Youth in the U.S.: Testing the Socioeconomic Gradient Hypothesis

    Directory of Open Access Journals (Sweden)

    Jeremy Reed Porter

    2014-12-01

    Full Text Available Adolescent obesity has increased three-fold in the U.S. during the last three decades. While this trend is well-known, relatively little is known about differences in obesity across the rural-urban continuum. This research addresses that gap by testing for such a relationship across time while accounting for variations in familial socioeconomic status.  Using 1986-2004 Monitoring the Future (MTF survey data, we estimate recent trends in rural-urban body weight, also testing for potential differences among the rural, small town, and urban high school seniors along socioeconomic gradients. Statistically significant differences disfavoring rural high school seniors in their BMI, their risk for the onset of obesity, and obesity itself over the past decade are identified, with significant interactions between demographics and parental education levels driving the largest disparities. These findings are rich and speak directly to the allocation of public health resources aimed at addressing issues associated with the adolescent obesity epidemic.

  5. Long-term job insecurity, job satisfaction and organisational attitudes: Test of Warr’s Curvilinear Hypothesis

    Directory of Open Access Journals (Sweden)

    Hans De Witte

    2005-10-01

    Full Text Available Research suggests that job insecurity is an important work stressor, negatively affecting well-being and organisational attitudes and behaviours. This article concentrates on two often ignored issues in this field. First, the consequences of long-term job insecurity regarding job satisfaction, the evaluation of management and organisational attitudes are analysed. Secondly, Warr’s assumption of curvilinear associations between job insecurity and well-being is tested, and extended to the evaluation of management and organisational attitudes. The hypotheses are tested with data of 769 employees from various branches of a large European multinational company. In total, 15 reliable scales were used to test the hypotheses. The results show that 48,2% of the interviewees had worries about their long-term job security. Separate analyses of variance showed that long-term job insecurity was associated with two thirds of the scales. Long-term job insecurity was associated with lower job satisfaction, lower organisational attitudes and a lower evaluation of supervisors and management. Warr’s assumption of curvilinear associations with job insecurity was not corroborated, however. Suggestions for practice and for future research are discussed. Opsomming Navorsing stel voor dat werksonsekerheid ’n belangrike werk stressor is en dat dit welstand, organisasie gesindhede en gedrag negetief affekteer. Die artikel konsentreer op twee onderwerpe in hierdie veld wat gereeld geignoreer word. Eerstens word die gevolge van langtermyn werksonsekerheid met betrekking tot werkstevredenheid, die evaluering van bestuur en organisasiegesindhede geanaliseer. Tweedens, is Warr se aanames van kromlynige verhoudings tussen werksonsekerheid en welstand getoets, en uitgebrei tot die evaluasie van bestuur en organisasiegesindhede. Die hipotese is getoets met data van 769 werknemers van verskeie takke van ’n groot Europese multinasionale maatskappy. Daar is in totaal 15

  6. Predictability of machine learning techniques to forecast the trends of market index prices: Hypothesis testing for the Korean stock markets.

    Science.gov (United States)

    Pyo, Sujin; Lee, Jaewook; Cha, Mincheol; Jang, Huisu

    2017-01-01

    The prediction of the trends of stocks and index prices is one of the important issues to market participants. Investors have set trading or fiscal strategies based on the trends, and considerable research in various academic fields has been studied to forecast financial markets. This study predicts the trends of the Korea Composite Stock Price Index 200 (KOSPI 200) prices using nonparametric machine learning models: artificial neural network, support vector machines with polynomial and radial basis function kernels. In addition, this study states controversial issues and tests hypotheses about the issues. Accordingly, our results are inconsistent with those of the precedent research, which are generally considered to have high prediction performance. Moreover, Google Trends proved that they are not effective factors in predicting the KOSPI 200 index prices in our frameworks. Furthermore, the ensemble methods did not improve the accuracy of the prediction.

  7. Predictability of machine learning techniques to forecast the trends of market index prices: Hypothesis testing for the Korean stock markets.

    Directory of Open Access Journals (Sweden)

    Sujin Pyo

    Full Text Available The prediction of the trends of stocks and index prices is one of the important issues to market participants. Investors have set trading or fiscal strategies based on the trends, and considerable research in various academic fields has been studied to forecast financial markets. This study predicts the trends of the Korea Composite Stock Price Index 200 (KOSPI 200 prices using nonparametric machine learning models: artificial neural network, support vector machines with polynomial and radial basis function kernels. In addition, this study states controversial issues and tests hypotheses about the issues. Accordingly, our results are inconsistent with those of the precedent research, which are generally considered to have high prediction performance. Moreover, Google Trends proved that they are not effective factors in predicting the KOSPI 200 index prices in our frameworks. Furthermore, the ensemble methods did not improve the accuracy of the prediction.

  8. Zero- vs. one-dimensional, parametric vs. non-parametric, and confidence interval vs. hypothesis testing procedures in one-dimensional biomechanical trajectory analysis.

    Science.gov (United States)

    Pataky, Todd C; Vanrenterghem, Jos; Robinson, Mark A

    2015-05-01

    Biomechanical processes are often manifested as one-dimensional (1D) trajectories. It has been shown that 1D confidence intervals (CIs) are biased when based on 0D statistical procedures, and the non-parametric 1D bootstrap CI has emerged in the Biomechanics literature as a viable solution. The primary purpose of this paper was to clarify that, for 1D biomechanics datasets, the distinction between 0D and 1D methods is much more important than the distinction between parametric and non-parametric procedures. A secondary purpose was to demonstrate that a parametric equivalent to the 1D bootstrap exists in the form of a random field theory (RFT) correction for multiple comparisons. To emphasize these points we analyzed six datasets consisting of force and kinematic trajectories in one-sample, paired, two-sample and regression designs. Results showed, first, that the 1D bootstrap and other 1D non-parametric CIs were qualitatively identical to RFT CIs, and all were very different from 0D CIs. Second, 1D parametric and 1D non-parametric hypothesis testing results were qualitatively identical for all six datasets. Last, we highlight the limitations of 1D CIs by demonstrating that they are complex, design-dependent, and thus non-generalizable. These results suggest that (i) analyses of 1D data based on 0D models of randomness are generally biased unless one explicitly identifies 0D variables before the experiment, and (ii) parametric and non-parametric 1D hypothesis testing provide an unambiguous framework for analysis when one׳s hypothesis explicitly or implicitly pertains to whole 1D trajectories. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Testing the social dog hypothesis: are dogs also more skilled than chimpanzees in non-communicative social tasks?

    Science.gov (United States)

    Wobber, Victoria; Hare, Brian

    2009-07-01

    Relative to non-human primates, domestic dogs possess a number of social skills that seem exceptional-particularly in solving problems involving cooperation and communication with humans. However, the degree to which dogs' unusual skills are contextually specialized is still unclear. Here, we presented dogs with a social problem that did not require them to use cooperative-communicative cues and compared their performance to that of chimpanzees to assess the extent of dogs' capabilities relative to those of non-human primates. We tested the abilities of dogs and chimpanzees to inhibit previously learned responses by using a social and a non-social version of a reversal learning task. In contrast to previous findings in cooperative-communicative social tasks, dogs were not more skilled on the social task than the non-social task, while chimpanzees were significantly better in the social paradigm. Chimpanzees were able to inhibit their prior learning better and more quickly in the social paradigm than they were in the non-social paradigm, while dogs took more time to inhibit what they had learned in both versions of the task. These results suggest that the dogs' sophisticated social skills in using human social cues may be relatively specialized as a result of domestication.

  10. Molecular and Morphological Differentiation of Common Dolphins (Delphinus sp.) in the Southwestern Atlantic: Testing the Two Species Hypothesis in Sympatry

    Science.gov (United States)

    Cunha, Haydée A.; de Castro, Rocio Loizaga; Secchi, Eduardo R.; Crespo, Enrique A.; Lailson-Brito, José; Azevedo, Alexandre F.; Lazoski, Cristiano; Solé-Cava, Antonio M.

    2015-01-01

    The taxonomy of common dolphins (Delphinus sp.) has always been controversial, with over twenty described species since the original description of the type species of the genus (Delphinus delphis Linnaeus, 1758). Two species and four subspecies are currently accepted, but recent molecular data have challenged this view. In this study we investigated the molecular taxonomy of common dolphins through analyses of cytochrome b sequences of 297 individuals from most of their distribution. We included 37 novel sequences from the Southwestern Atlantic Ocean, a region where the short- and long-beaked morphotypes occur in sympatry, but which had not been well sampled before. Skulls of individuals from the Southwestern Atlantic were measured to test the validity of the rostral index as a diagnostic character and confirmed the presence of the two morphotypes in our genetic sample. Our genetic results show that all common dolphins in the Atlantic Ocean belong to a single species, Delphinus delphis. According to genetic data, the species Delphinus capensis is invalid. Long-beaked common dolphins from the Northeastern Pacific Ocean may constitute a different species. Our conclusions prompt the need for revision of currently accepted common dolphin species and subspecies and of Delphinus delphis distribution. PMID:26559411

  11. Study of 14O as a test of the unitarity of the CKM matrix and the CVC hypothesis

    International Nuclear Information System (INIS)

    Burke, Jason Timothy

    2004-01-01

    The study of superallowed beta decay in nuclei, in conjunction with other experiments, provide a test of the unitarity of the quark mixing matrix or CKM matrix. Nonunitarity of the CKM matrix could imply the existence of a fourth generation of quarks, right handed currents in the weak interaction, and/or new exotic fermions. Advances in radioactive beam techniques allow the creation of nearly pure samples of nuclei for beta decay studies. The subject of this thesis is the development of a radioactive beam of 14O and the study of the 14O halflife and branching ratio. The radioactive beam is produced by ionizing 12C14O radioactive gas and then accelerating with an ECR ion source. The 14O nucleus decays via superallowed beta decay with a branching ratio > 99 percent. The low Z of 14O is important for calculating reliable corrections to the beta decay that generally increase in with Z. The > 99 percent branching ratio can be established with modest precision on the complementary branching ratio.When this work began the experimentally determined CKM matrix was nonunitary by 2.5 standard deviations. Recent studies of Kaon, Hyperon, and B meson decays have been used to determine Vus and Vub matrix elements. In this work the halflife and branching ratio of 14O are measured and used to establish Vud. The unitarity of the CKM matrix is then assessed. The halflife of 14O was determined to be 70.683 +- 0.015 s and the GamowTeller branching ratio was found to be 0.643 +- 0.020 percent. Using these results the value of Vud is 0.9738 +- 0.0005. Incorporating the new values for Vus of 0.2272 +- 0.0030 and Vub of 0.0035 +- 0.0015 the squared sum of the first row of the CKM matrix is 0.9999 +- 0.0017 which is consistent with unitarity

  12. Contrasting patterns of larval mortality in two sympatric riverine fish species: a test of the critical period hypothesis.

    Directory of Open Access Journals (Sweden)

    Nicole McCasker

    Full Text Available Understanding the causal mechanisms that determine recruitment success is critical to the effective conservation of wild fish populations. Although recruitment strength is likely determined during early life when mortality is greatest, few studies have documented age-specific mortality rates for fish during this period. We investigated age-specific mortality of individual cohorts of two species of riverine fish from yolksac larvae to juveniles, assaying for the presence of a "critical period": A time when mortality is unusually high. Early life stages of carp gudgeons (Hypseleotris spp. and unspecked hardyhead (Craterocephalus stercusmuscarum fulvus-two fishes that differ in fecundity, egg size and overlap between endogenous and exogenous feeding-were collected every second day for four months. We fitted survivorship curves to 22 carp gudgeon and 15 unspecked hardyhead four-day cohorts and tested several mortality functions. Mortality rates declined with age for carp gudgeon, with mean instantaneous mortality rates (-Z ranging from 1.40-0.03. In contrast, mortality rates for unspecked hardyhead were constant across the larval period, with a mean -Z of 0.15. There was strong evidence of a critical period for carp gudgeon larvae from hatch until 6 days old, and no evidence of a critical period for unspecked hardyhead. Total larval mortality for carp gudgeon and unspecked hardyhead up to 24 days of age was estimated to be 97.8 and 94.3%, respectively. We hypothesise that life history strategy may play an important role in shaping overall mortality and the pattern of mortality during early life in these two fishes.

  13. Cyanobacteria enhance methylmercury production: a hypothesis tested in the periphyton of two lakes in the Pantanal floodplain, Brazil.

    Science.gov (United States)

    Lázaro, Wilkinson L; Guimarães, Jean Remy D; Ignácio, Aurea R A; Da Silva, Carolina J; Díez, Sergi

    2013-07-01

    The toxic potential of mercury (Hg) in aquatic systems is due to the presence and production of methylmercury (MeHg). Recent studies in tropical floodplain environments showed that periphyton associated with the roots of aquatic macrophytes produce MeHg. Periphyton communities are the first link in the food chain and one of the main MeHg sources in aquatic environments. The aim of this work was to test the hypotheses that the algal community structure affects potential methylation, and ecologically distinct communities with different algal and bacterial densities directly affect the formation of MeHg in the roots of macrophytes. To evaluate these, net MeHg production in the roots of Eichhornia crassipes in relation to the taxonomic structure of associated periphytic algae was evaluated. Macrophyte root samples were collected in the dry and flood season from two floodplain lakes in the Pantanal (Brazil). These lakes have different ecological conditions as a function of their lateral hydrological connectivity with the Paraguay River that is different during times of drought. Results indicated that MeHg production was higher in the flood season than in the dry season. MeHg production rates were higher in the disconnected lake in comparison to the connected lake during the dry season. MeHg production exhibited a strong positive co-variation with cyanobacteria abundance (R(2)=0.78; pcyanobacteria are associated with higher rates of methylation in aquatic systems. This suggests that cyanobacteria could be a proxy for sites of MeHg production in some natural aquatic environments. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Social and demographic effects of anthropogenic mortality: a test of the compensatory mortality hypothesis in the red wolf.

    Directory of Open Access Journals (Sweden)

    Amanda M Sparkman

    Full Text Available Whether anthropogenic mortality is additive or compensatory to natural mortality in animal populations has long been a question of theoretical and practical importance. Theoretically, under density-dependent conditions populations compensate for anthropogenic mortality through decreases in natural mortality and/or increases in productivity, but recent studies of large carnivores suggest that anthropogenic mortality can be fully additive to natural mortality and thereby constrain annual survival and population growth rate. Nevertheless, mechanisms underlying either compensatory or additive effects continue to be poorly understood. Using long-term data on a reintroduced population of the red wolf, we tested for evidence of additive vs. compensatory effects of anthropogenic mortality on annual survival and population growth rates, and the preservation and reproductive success of breeding pairs. We found that anthropogenic mortality had a strong additive effect on annual survival and population growth rate at low population density, though there was evidence for compensation in population growth at high density. When involving the death of a breeder, anthropogenic mortality was also additive to natural rates of breeding pair dissolution, resulting in a net decrease in the annual preservation of existing breeding pairs. However, though the disbanding of a pack following death of a breeder resulted in fewer recruits per litter relative to stable packs, there was no relationship between natural rates of pair dissolution and population growth rate at either high or low density. Thus we propose that short-term additive effects of anthropogenic mortality on population growth in the red wolf population at low density were primarily a result of direct mortality of adults rather than indirect socially-mediated effects resulting in reduced recruitment. Finally, we also demonstrate that per capita recruitment and the proportion of adults that became

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

    Science.gov (United States)

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

    2014-05-01

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

  16. Dormancy and Recovery Testing for Biological Wastewater Processors

    Science.gov (United States)

    Hummerick, Mary F.; Coutts, Janelle L.; Lunn, Griffin M.; Spencer, LaShelle; Khodadad, Christina L.; Birmele, Michele N.; Frances, Someliz; Wheeler, Raymond

    2015-01-01

    Resource recovery and recycling waste streams to usable water via biological water processors is a plausible component of an integrated water purification system. Biological processing as a pretreatment can reduce the load of organic carbon and nitrogen compounds entering physiochemical systems downstream. Aerated hollow fiber membrane bioreactors, have been proposed and studied for a number of years as an approach for treating wastewater streams for space exploration.

  17. Biological Races in Humans

    OpenAIRE

    Templeton, Alan R.

    2013-01-01

    Races may exist in humans in a cultural sense, but biological concepts of race are needed to access their reality in a non-species-specific manner and to see if cultural categories correspond to biological categories within humans. Modern biological concepts of race can be implemented objectively with molecular genetic data through hypothesis-testing. Genetic data sets are used to see if biological races exist in humans and in our closest evolutionary relative, the chimpanzee. Using the two m...

  18. Hypothesis Validity of Clinical Research.

    Science.gov (United States)

    Wampold, Bruce E.; And Others

    1990-01-01

    Describes hypothesis validity as extent to which research results reflect theoretically derived predictions about relations between or among constructs. Discusses role of hypotheses in theory testing. Presents four threats to hypothesis validity: (1) inconsequential research hypotheses; (2) ambiguous research hypotheses; (3) noncongruence of…

  19. Robust estimation and hypothesis testing

    CERN Document Server

    Tiku, Moti L

    2004-01-01

    In statistical theory and practice, a certain distribution is usually assumed and then optimal solutions sought. Since deviations from an assumed distribution are very common, one cannot feel comfortable with assuming a particular distribution and believing it to be exactly correct. That brings the robustness issue in focus. In this book, we have given statistical procedures which are robust to plausible deviations from an assumed mode. The method of modified maximum likelihood estimation is used in formulating these procedures. The modified maximum likelihood estimators are explicit functions of sample observations and are easy to compute. They are asymptotically fully efficient and are as efficient as the maximum likelihood estimators for small sample sizes. The maximum likelihood estimators have computational problems and are, therefore, elusive. A broad range of topics are covered in this book. Solutions are given which are easy to implement and are efficient. The solutions are also robust to data anomali...

  20. Biological hardening and genetic fidelity testing of micro-cloned ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-04-17

    Apr 17, 2008 ... vitro conditions as the cultured plants have non functional stomata, weak root system and poorly developed ... propagation techniques in C. borivilianum have so far met with limited success because of high ..... Biological hardening of tissue culture raised tea plants through rhizosphere bacteria. Biotechnol.

  1. Video and HTML: Testing Online Tutorial Formats with Biology Students

    Science.gov (United States)

    Craig, Cindy L.; Friehs, Curt G.

    2013-01-01

    This study compared two common types of online information literacy tutorials: a streaming media tutorial using animation and narration and a text-based tutorial with static images. Nine sections of an undergraduate biology lab class (234 students total) were instructed by a librarian on how to use the BIOSIS Previews database. Three sections…

  2. Hypothesis: Low frequency heart rate variability (LF-HRV) is an input for undisclosed yet biological adaptive control, governing the cardiovascular regulations to assure optimal functioning.

    Science.gov (United States)

    Gabbay, Uri; Bobrovsky, Ben Zion

    2012-02-01

    Cardiovascular regulation is considered today as having three levels: autoregulations, neural regulations and hormonal regulations. We hypothesize that the cardiovascular regulation has an additional (fourth) control level which is outer, hierarchical (adaptive) loop where LF-HRV amplitude serves as a reference input which the neural cardiovascular center detects and responses in order to maintain LF-HRV around some prescribed level. Supporting evidences: LF-HRV absence during artificial cardiac pacing may be associated with "pacemaker syndrome" which had not been sufficiently understood regardless of apparently unimpaired cardiovascular performance. The hypothesis may provide an essential basis for understanding several cardiovascular morbidities and insight toward diagnostic measures and treatments (including but not limited to adding variability to the pulse generator of artificial pacemakers to eliminate "pace maker syndrome"). Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Failure cause and failure rate evaluation on pumps of BWR plants in PSA. Hypothesis testing for typical or plant specific failure rate of pumps

    International Nuclear Information System (INIS)

    Sanada, Takahiro; Nakamura, Makoto

    2009-01-01

    In support of domestic nuclear industry effort to gather and analyze failure data of components concerning nuclear power plants, Nuclear Information Archives (NUCIA) are published for useful information to help PSA. This report focuses on NUCIA pertaining to pumps in domestic nuclear power plants, and provides the reliable estimation on failure rate of pumps resulting from failure cause analysis and hypothesis testing of classified and plant specific failure rate of pumps for improving quality in PSA. The classified and plant specific failure rate of pumps are estimated by analyzing individual domestic nuclear power plant's data of 26 Boiling Water Reactors (BWRs) concerning functionally structurally classified pump failures reported from beginning of commercial operation to March 31, 2007. (author)

  4. The role of effort in influencing the effect of anxiety on performance: testing the conflicting predictions of processing efficiency theory and the conscious processing hypothesis.

    Science.gov (United States)

    Wilson, Mark; Smith, Nickolas C; Holmes, Paul S

    2007-08-01

    The aim of this study was to test the conflicting predictions of processing efficiency theory (PET) and the conscious processing hypothesis (CPH) regarding effort's role in influencing the effects of anxiety on a golf putting task. Mid-handicap golfers made a series of putts to target holes under two counterbalanced conditions designed to manipulate the level of anxiety experienced. The effort exerted on each putting task was assessed though self-report, psychophysiological (heart rate variability) and behavioural (pre-putt time and glances at the target) measures. Performance was assessed by putting error. Results were generally more supportive of the predictions of PET rather than the CPH as performance was maintained for some performers despite increased state anxiety and a reduction in processing efficiency. The findings of this study support previous research suggesting that both theories offer useful theoretical frameworks for examining the relationship between anxiety and performance in sport.

  5. Using Data-Collection Sensors to Improve Reasoning About Experiment Design and Hypothesis Testing: An Undergraduate Course for Underrepresented Minorities Pursuing Careers Astrophysics Research

    Science.gov (United States)

    Robbins, Dennis M.; Ford, K. E. Saavik

    2015-01-01

    Strategies to improve the retention of underrepresented students in STEM fields include directly targeted programs and specialized courses. The NSF-supported 'AstroCom NYC' program, a collaboration of the City University of New York, American Museum of Natural History (AMNH), and Columbia University is one example of such a program with the explicit goal of increasing the participation of underrepresented minorities in astronomy and astrophysics through pedagogical mentoring and research experiences for undergraduate students. In addition, 'AstroCom NYC' provides students with a semester-long specialized course emphasizing scientific reasoning and mathematical modeling. The course curriculum uses computers and interfaced digital probeware (sensors) in a laboratory environment that encourages collaborative and active learning.We share course materials on preparing students to reason about control of variable experiment design and hypothesis testing and provide course data on student understanding of scientific reasoning, mathematical modeling and views about science.

  6. Respirator Filter Efficiency Testing Against Particulate and Biological Aerosols Under Moderate to High Flow Rates

    National Research Council Canada - National Science Library

    Richardson, Aaron W; Eshbaugh, Jonathan P; Hofacre, Kent C; Gardner, Paul D

    2006-01-01

    ...) and biological test aerosols under breather flow rates associated with high work rates. The inert test challenges consisted of solid and oil aerosols having nominal diameters ranging from 0.02...

  7. A test of the central-marginal hypothesis using population genetics and ecological niche modelling in an endemic salamander (Ambystoma barbouri).

    Science.gov (United States)

    Micheletti, Steven J; Storfer, Andrew

    2015-03-01

    The central-marginal hypothesis (CMH) predicts that population size, genetic diversity and genetic connectivity are highest at the core and decrease near the edges of species' geographic distributions. We provide a test of the CMH using three replicated core-to-edge transects that encompass nearly the entire geographic range of the endemic streamside salamander (Ambystoma barbouri). We confirmed that the mapped core of the distribution was the most suitable habitat using ecological niche modelling (ENM) and via genetic estimates of effective population sizes. As predicted by the CMH, we found statistical support for decreased genetic diversity, effective population size and genetic connectivity from core to edge in western and northern transects, yet not along a southern transect. Based on our niche model, habitat suitability is lower towards the southern range edge, presumably leading to conflicting core-to-edge genetic patterns. These results suggest that multiple processes may influence a species' distribution based on the heterogeneity of habitat across a species' range and that replicated sampling may be needed to accurately test the CMH. Our work also emphasizes the importance of identifying the geographic range core with methods other than using the Euclidean centre on a map, which may help to explain discrepancies among other empirical tests of the CMH. Assessing core-to-edge population genetic patterns across an entire species' range accompanied with ENM can inform our general understanding of the mechanisms leading to species' geographic range limits. © 2015 John Wiley & Sons Ltd.

  8. Biologically Relevant Exposure Science for 21st Century Toxicity Testing

    Science.gov (United States)

    High visibility efforts in toxicity testing and computational toxicology including the recent NRC report, Toxicity Testing in the 21st Century: a Vision and Strategy (NRC, 2007), raise important research questions and opportunities for the field of exposure science. The authors ...

  9. Testing the fetal overnutrition hypothesis; the relationship of maternal and paternal adiposity to adiposity, insulin resistance and cardiovascular risk factors in Indian children.

    Science.gov (United States)

    Veena, Sargoor R; Krishnaveni, Ghattu V; Karat, Samuel C; Osmond, Clive; Fall, Caroline H D

    2013-09-01

    We aimed to test the fetal overnutrition hypothesis by comparing the associations of maternal and paternal adiposity (sum of skinfolds) with adiposity and cardiovascular risk factors in children. Children from a prospective birth cohort had anthropometry, fat percentage (bio-impedance), plasma glucose, insulin and lipid concentrations and blood pressure measured at 9.5 years of age. Detailed anthropometric measurements were recorded for mothers (at 3±2 weeks’ gestation) and fathers (5 years following the index pregnancy). Holdsworth Memorial Hospital, Mysore, India. Children (n 504), born to mothers with normal glucose tolerance during pregnancy. Twenty-eight per cent of mothers and 38% of fathers were overweight/ obese (BMI≥25.0 kg/m²), but only 4% of the children were overweight/obese (WHO age- and sex-specific BMI≥18.2 kg/m²). The children’s adiposity (BMI, sum of skinfolds, fat percentage and waist circumference), fasting insulin concentration and insulin resistance increased with increasing maternal and paternal sum of skinfolds adjusted for the child’s sex, age and socio-economic status. Maternal and paternal effects were similar. The associations with fasting insulin and insulin resistance were attenuated after adjusting for the child’s current adiposity. In this population, both maternal and paternal adiposity equally predict adiposity and insulin resistance in the children. This suggests that shared family environment and lifestyle, or genetic/epigenetic factors, influence child adiposity. Our findings do not support the hypothesis that there is an intrauterine overnutrition effect of maternal adiposity in non-diabetic pregnancies, although we cannot rule out such an effect in cases of extreme maternal obesity, which is rare in our population.

  10. Too much food may cause reduced growth of blue mussels (Mytilus edulis) - Test of hypothesis and new 'high Chl a BEG-model'

    Science.gov (United States)

    Larsen, Poul S.; Lüskow, Florian; Riisgård, Hans Ulrik

    2018-04-01

    Growth of the blue mussel (Mytilus edulis) is closely related to the biomass of phytoplankton (expressed as concentration of chlorophyll a, Chl a), but the effect of too much food in eutrophicated areas has so far been overlooked. The hypothesis addressed in the present study suggests that high Chl a concentrations (> about 8 μg Chl a l-1) result in reduced growth because mussels are not evolutionarily adapted to utilize such high phytoplankton concentrations and to physiologically regulate the amount of ingested food in such a way that the growth rate remains high and constant. We first make a comparison of literature values for actually measured weight-specific growth rates (μ, % d-1) of small (20 to 25 mm) M. edulis, either grown in controlled laboratory experiments or in net bags in Danish waters, as a function of Chl a. A linear increase up to about μ = 8.3% d-1 at 8.1 μg Chl a l-1 fits the "standard BEG-model" after which a marked decrease takes place, and this supports the hypothesis. A "high Chl a BEG-model", applicable to newly settled post-metamorphic and small juvenile (non-spawning) mussels in eutrophicated Danish and other temperate waters, is developed and tested, and new data from a case study in which the growth of mussels in net bags was measured along a Chl a gradient are presented. Finally, we discuss the phenomenon of reduced growth of mussels in eutrophicated areas versus a possible impact of low salinity. It is concluded that it is difficult to separate the effect of salinity from the effect of Chl a, but the present study shows that too much food may cause reduced growth of mussels in eutrophicated marine areas regardless of high or moderate salinity above about 10 psu.

  11. Does cooperation increase helpers' later success as breeders? A test of the skills hypothesis in the cooperatively displaying lance-tailed manakin.

    Science.gov (United States)

    DuVal, Emily H

    2013-07-01

    Experience improves individual performance in many tasks. Pre-breeding cooperation may provide important experience that improves later success as a breeder, offering one compelling explanation for why some individuals delay reproduction to help others breed (the 'skills hypothesis'). However, confounding effects of age, quality and alternative selective benefits have complicated rigorous tests of this hypothesis. Male lance-tailed manakins perform cooperative courtship displays involving partnerships between unrelated alpha and beta males, and alphas monopolize resulting copulations. Beta males therefore do not receive immediate direct or indirect fitness benefits, but may gain skills during cooperation that increase their later success as an alpha. To date, however, the effect of cooperative experience on later success as a breeder has never been tested in any cooperatively displaying taxon. The effects of prior cooperative experience on reproductive success of alpha lance-tailed manakins were analysed in a mixed model framework using 12 years of information on cooperative experience and annual and lifetime genetic reproductive success for 57 alpha males. Models included previously identified effects of age and alpha tenure. Individual-level random effects controlled for quality differences to test for an independent influence of beta experience on success. Males accumulated up to 5 years of beta experience before becoming alphas, but 42·1% of alphas had no prior beta experience. Betas became alphas later in life, and experienced significantly lower reproductive success in their final year as alpha than males that were never beta, but did not have higher lifetime success or longer alpha tenures. Differences in patterns of annual siring success were best explained by age-dependent patterns of reproductive improvement and senescence among alphas, not beta experience. Cooperative experience does not increase relative breeding success for male lance-tailed manakins

  12. Rapid ATP-Glow for Biological Decontamination Efficacy Test

    National Research Council Canada - National Science Library

    Ho, Winston

    2003-01-01

    Report developed under STTR contract for topic "Army02-T016". A plate count method has been traditionally used to determine the effectiveness of anti-microbial agents in decontamination efficacy testing...

  13. Testing the Hypothesis of Multiple Origins of Holoparasitism in Orobanchaceae: Phylogenetic Evidence from the Last Two Unplaced Holoparasitic Genera, Gleadovia and Phacellanthus

    Directory of Open Access Journals (Sweden)

    Weirui Fu

    2017-08-01

    Full Text Available Orobanchaceae is the largest family among the parasitic angiosperms. It comprises non-parasites, hemi- and holoparasites, making this family an ideal test case for studying the evolution of parasitism. Previous phylogenetic analyses showed that holoparasitism had arisen at least three times from the hemiparasitic taxa in Orobanchaceae. Until now, however, not all known genera of Orobanchaceae were investigated in detail. Among them, the unknown phylogenetic positions of the holoparasites Gleadovia and Phacellanthus are the key to testing how many times holoparasitism evolved. Here, we provide clear evidence for the first time that they are members of the tribe Orobancheae, using sequence data from multiple loci (nuclear genes ITS, PHYA, PHYB, and plastid genes rps2, matK. Gleadovia is an independent lineage whereas Phacellanthus should be merged into genus Orobanche section Orobanche. Our results unambiguously support the hypothesis that there are only three origins of holoparasitism in Orobanchaceae. Divergence dating reveals for the first time that the three origins of holoparasitism were not synchronous. Our findings suggest that holoparasitism can persist in specific clades for a long time and holoparasitism may evolve independently as an adaptation to certain hosts.

  14. Operational lessons learned in conducting a multi-country collaboration for vaccine safety signal verification and hypothesis testing: The global vaccine safety multi country collaboration initiative.

    Science.gov (United States)

    Guillard-Maure, Christine; Elango, Varalakshmi; Black, Steven; Perez-Vilar, Silvia; Castro, Jose Luis; Bravo-Alcántara, Pamela; Molina-León, Helvert Felipe; Weibel, Daniel; Sturkenboom, Miriam; Zuber, Patrick L F

    2018-01-08

    Timely and effective evaluation of vaccine safety signals for newly developed vaccines introduced in low and middle- income countries (LMICs) is essential. The study tested the development of a global network of hospital-based sentinel sites for vaccine safety signal verification and hypothesis testing. Twenty-six sentinel sites in sixteen countries across all WHO regions participated, and 65% of the sites were from LMIC. We describe the process for the establishment and operationalization of such a network and the lessons learned in conducting a multi-country collaborative initiative. 24 out of the 26 sites successfully contributed data for the global analysis using standardised tools and procedures. Our study successfully confirmed the well-known risk estimates for the outcomes of interest. The main challenges faced by investigators were lack of adequate information in the medical records for case ascertainment and classification, and access to immunization data. The results suggest that sentinel hospitals intending to participate in vaccine safety studies strengthen their systems for discharge diagnosis coding, medical records and linkage to vaccination data. Our study confirms that a multi-country hospital-based network initiative for vaccine safety monitoring is feasible and demonstrates the validity and utility of large collaborative international studies to monitor the safety of new vaccines introduced in LMICs. Copyright © 2017. Published by Elsevier Ltd.

  15. 40 CFR 230.61 - Chemical, biological, and physical evaluation and testing.

    Science.gov (United States)

    2010-07-01

    ... appropriate physical and chemical environmental characteristics. (d) Physical tests and evaluation. The effect... physical tests and evaluations as are justified and deemed necessary. Such tests may include sieve tests... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Chemical, biological, and physical...

  16. Biological Gender Differences in Students' Errors on Mathematics Achievement Tests

    Science.gov (United States)

    Stewart, Christie; Root, Melissa M.; Koriakin, Taylor; Choi, Dowon; Luria, Sarah R.; Bray, Melissa A.; Sassu, Kari; Maykel, Cheryl; O'Rourke, Patricia; Courville, Troy

    2017-01-01

    This study investigated developmental gender differences in mathematics achievement, using the child and adolescent portion (ages 6-19 years) of the Kaufman Test of Educational Achievement-Third Edition (KTEA-3). Participants were divided into two age categories: 6 to 11 and 12 to 19. Error categories within the Math Concepts & Applications…

  17. Memory in astrocytes: a hypothesis

    Directory of Open Access Journals (Sweden)

    Caudle Robert M

    2006-01-01

    Full Text Available Abstract Background Recent work has indicated an increasingly complex role for astrocytes in the central nervous system. Astrocytes are now known to exchange information with neurons at synaptic junctions and to alter the information processing capabilities of the neurons. As an extension of this trend a hypothesis was proposed that astrocytes function to store information. To explore this idea the ion channels in biological membranes were compared to models known as cellular automata. These comparisons were made to test the hypothesis that ion channels in the membranes of astrocytes form a dynamic information storage device. Results Two dimensional cellular automata were found to behave similarly to ion channels in a membrane when they function at the boundary between order and chaos. The length of time information is stored in this class of cellular automata is exponentially related to the number of units. Therefore the length of time biological ion channels store information was plotted versus the estimated number of ion channels in the tissue. This analysis indicates that there is an exponential relationship between memory and the number of ion channels. Extrapolation of this relationship to the estimated number of ion channels in the astrocytes of a human brain indicates that memory can be stored in this system for an entire life span. Interestingly, this information is not affixed to any physical structure, but is stored as an organization of the activity of the ion channels. Further analysis of two dimensional cellular automata also demonstrates that these systems have both associative and temporal memory capabilities. Conclusion It is concluded that astrocytes may serve as a dynamic information sink for neurons. The memory in the astrocytes is stored by organizing the activity of ion channels and is not associated with a physical location such as a synapse. In order for this form of memory to be of significant duration it is necessary

  18. Physiopathological Hypothesis of Cellulite

    OpenAIRE

    de Godoy, Jos? Maria Pereira; de Godoy, Maria de F?tima Guerreiro

    2009-01-01

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

  19. Genomic tests of the species-pump hypothesis: Recent island connectivity cycles drive population divergence but not speciation in Caribbean crickets across the Virgin Islands.

    Science.gov (United States)

    Papadopoulou, Anna; Knowles, L Lacey

    2015-06-01

    Harnessing the power of genomic scans, we test the debated "species pump" hypothesis that implicates repeated cycles of island connectivity and isolation as drivers of divergence. This question has gone understudied given the limited resolution of past molecular markers for studying such dynamic phenomena. With an average of 32,000 SNPs from the genome of 136 individuals from 10 populations of a Caribbean flightless ground cricket species (Amphiacusta sanctaecrucis) and a complementary set of statistical approaches, we infer a stepping-stone colonization model and high levels of genetic differentiation across the Virgin Islands, which have been periodically interconnected until 8 ka. Estimates of divergence times from models based on the site frequency spectrum coincide with a period of repeated connection and fragmentation of the islands at 75-130 ka. These results are consistent with a role of island connectivity cycles in promoting genomic divergence and indicate that the genetic distinctiveness of island populations has persisted despite subsequent and extended interisland connections identified from bathymetric data. We discuss these findings in the broader context of Caribbean biogeography, and more specifically why high levels of genomic divergence across the Virgin Islands associated with repeated connectivity cycles do not actually translate into species diversification. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  20. Does Drug Use Inhibit Crime Deceleration or Does Crime Inhibit Drug Use Deceleration? A Test of the Reciprocal Risk Postulate of the Worst of Both Worlds Hypothesis.

    Science.gov (United States)

    Walters, Glenn D

    2018-01-16

    Prior research has shown that ongoing drug use inhibits the commonly reported maturing out of crime process and that ongoing crime inhibits the commonly reported maturing out of drug use process. To test the predictive efficacy of drug use for crime deceleration and of crime for drug deceleration using a prospective analysis of data on a group of 524 male California Youth Authority parolees to see if both effects exist simultaneously. A two-equation regression analysis of Year 3 arrests and illicit drug use was performed, controlling for age, race, marital status, employment status, and number of months free in the community. It was determined that illicit drug use at Year 2 predicted an increase in arrests between the first and third years of the analysis and arrests at Year 2 predicted an increase in illicit drug use over this same time period. Alcohol use, on the other hand, failed to predict a change in arrests and arrests failed to predict a change in alcohol use. The results of this study suggest that illicit drug use may inhibit the natural maturing out of crime process observed in emerging adults whereas involvement in crime may inhibit the natural maturing out of illicit drug use process. These findings not only support the reciprocal risk postulate from the Worst of Both Worlds hypothesis but also have implications for risk prediction, risk management, and treatment.

  1. Examining age-related shared variance between face cognition, vision, and self-reported physical health: a test of the common cause hypothesis for social cognition

    Science.gov (United States)

    Olderbak, Sally; Hildebrandt, Andrea; Wilhelm, Oliver

    2015-01-01

    The shared decline in cognitive abilities, sensory functions (e.g., vision and hearing), and physical health with increasing age is well documented with some research attributing this shared age-related decline to a single common cause (e.g., aging brain). We evaluate the extent to which the common cause hypothesis predicts associations between vision and physical health with social cognition abilities specifically face perception and face memory. Based on a sample of 443 adults (17–88 years old), we test a series of structural equation models, including Multiple Indicator Multiple Cause (MIMIC) models, and estimate the extent to which vision and self-reported physical health are related to face perception and face memory through a common factor, before and after controlling for their fluid cognitive component and the linear effects of age. Results suggest significant shared variance amongst these constructs, with a common factor explaining some, but not all, of the shared age-related variance. Also, we found that the relations of face perception, but not face memory, with vision and physical health could be completely explained by fluid cognition. Overall, results suggest that a single common cause explains most, but not all age-related shared variance with domain specific aging mechanisms evident. PMID:26321998

  2. Examining Age-Related Shared Variance Between Face Cognition, Vision, and Self-Reported Physical Health: A Test of the Common Cause Hypothesis for Social Cognition

    Directory of Open Access Journals (Sweden)

    Sally eOlderbak

    2015-08-01

    Full Text Available The shared decline in cognitive abilities, sensory functions (e.g., vision and hearing, and physical health with increasing age is well documented with some research attributing this shared age-related decline to a single common cause (e.g., aging brain. We evaluate the extent to which the common cause hypothesis predicts associations between vision and physical health with social cognition abilities, specifically face perception and face memory. Based on a sample of 443 adults (17 to 88 years old, we test a series of structural equation models, including Multiple Indicator Multiple Cause (MIMIC models, and estimate the extent to which vision and self-reported physical health are related to face perception and face memory through a common factor, before and after controlling for their fluid cognitive component and the linear effects of age. Results suggest significant shared variance amongst these constructs, with a common factor explaining some, but not all, of the shared age-related variance. Also, we found that the relations of face perception, but not face memory, with vision and physical health could be completely explained by fluid cognition. Overall, results suggest that a single common cause explains most, but not all age-related shared variance with domain specific aging mechanisms evident.

  3. Event rate and reaction time performance in ADHD: Testing predictions from the state regulation deficit hypothesis using an ex-Gaussian model.

    Science.gov (United States)

    Metin, Baris; Wiersema, Jan R; Verguts, Tom; Gasthuys, Roos; van Der Meere, Jacob J; Roeyers, Herbert; Sonuga-Barke, Edmund

    2014-12-06

    According to the state regulation deficit (SRD) account, ADHD is associated with a problem using effort to maintain an optimal activation state under demanding task settings such as very fast or very slow event rates. This leads to a prediction of disrupted performance at event rate extremes reflected in higher Gaussian response variability that is a putative marker of activation during motor preparation. In the current study, we tested this hypothesis using ex-Gaussian modeling, which distinguishes Gaussian from non-Gaussian variability. Twenty-five children with ADHD and 29 typically developing controls performed a simple Go/No-Go task under four different event-rate conditions. There was an accentuated quadratic relationship between event rate and Gaussian variability in the ADHD group compared to the controls. The children with ADHD had greater Gaussian variability at very fast and very slow event rates but not at moderate event rates. The results provide evidence for the SRD account of ADHD. However, given that this effect did not explain all group differences (some of which were independent of event rate) other cognitive and/or motivational processes are also likely implicated in ADHD performance deficits.

  4. The effects of testosterone on a viral infection in greenfinches (Carduelis chloris): an experimental test of the immunocompetence-handicap hypothesis.

    Science.gov (United States)

    Lindström, K M; Krakower, D; Lundström, J O; Silverin, B

    2001-01-22

    The immunocompetence-handicap hypothesis suggests that the honesty of quality signals could be guaranteed if testosterone (T) suppresses immune function while enhancing male ornaments. In addition, it has been proposed that the cost of enhancing ornaments should be highest for males with small ornaments. Recently, the assertion that T causes obligate immunosuppression has been questioned. In this study, we tested whether elevated T levels would increase susceptibility to a viral infection, and whether this hypothesized effect would be most pronounced in males with small ornaments. We surgically inserted T implants into 15 male greenfinches (Carduelis chloris) and control implants into a further 15 males. All birds were then infected with a naturally occurring virus (Sindbis virus, Alphavirus genus), and each bird's daily viraemia (blood virus concentration) was measured for seven days. The specific antibody response was measured for eight weeks. T-implanted males did not exhibit increased viraemia or decreased antibody response, and males with small and large ornaments did not respond differently to T implantation. We did, however, find that T implantation decreased viraemia early in the course of the infection and increased viraemia late in the infection. Thus, our results demonstrate that T may act both to increase and to decrease viraemia.

  5. Second-order asymptotics for quantum hypothesis testing in settings beyond i.i.d.—quantum lattice systems and more

    International Nuclear Information System (INIS)

    Datta, Nilanjana; Rouzé, Cambyse; Pautrat, Yan

    2016-01-01

    Quantum Stein’s lemma is a cornerstone of quantum statistics and concerns the problem of correctly identifying a quantum state, given the knowledge that it is one of two specific states (ρ or σ). It was originally derived in the asymptotic i.i.d. setting, in which arbitrarily many (say, n) identical copies of the state (ρ ⊗n or σ ⊗n ) are considered to be available. In this setting, the lemma states that, for any given upper bound on the probability α n of erroneously inferring the state to be σ, the probability β n of erroneously inferring the state to be ρ decays exponentially in n, with the rate of decay converging to the relative entropy of the two states. The second order asymptotics for quantum hypothesis testing, which establishes the speed of convergence of this rate of decay to its limiting value, was derived in the i.i.d. setting independently by Tomamichel and Hayashi, and Li. We extend this result to settings beyond i.i.d. Examples of these include Gibbs states of quantum spin systems (with finite-range, translation-invariant interactions) at high temperatures, and quasi-free states of fermionic lattice gases.

  6. Expertise for Teaching Biology Situated in the Context of Genetic Testing

    Science.gov (United States)

    van der Zande, Paul; Akkerman, Sanne F.; Brekelmans, Mieke; Waarlo, Arend Jan; Vermunt, Jan D.

    2012-01-01

    Contemporary genomics research will impact the daily practice of biology teachers who want to teach up-to-date genetics in secondary education. This article reports on a research project aimed at enhancing biology teachers' expertise for teaching genetics situated in the context of genetic testing. The increasing body of scientific knowledge…

  7. A Knowledge Base for Teaching Biology Situated in the Context of Genetic Testing

    Science.gov (United States)

    van der Zande, Paul; Waarlo, Arend Jan; Brekelmans, Mieke; Akkerman, Sanne F.; Vermunt, Jan D.

    2011-01-01

    Recent developments in the field of genomics will impact the daily practice of biology teachers who teach genetics in secondary education. This study reports on the first results of a research project aimed at enhancing biology teacher knowledge for teaching genetics in the context of genetic testing. The increasing body of scientific knowledge…

  8. Testing the Younger Dryas impact hypothesis with platinum-group elements (PGE), Re, and Os isotopes in sediments from Hall's Cave and Freidken Archaeological site, Texas

    Science.gov (United States)

    Sun, N.; Brandon, A. D.; Forman, S. L.

    2017-12-01

    The Younger Dryas impact hypothesis suggests that extraterrestrial (ET) object(s) hit and exploded over North America 12,900 years ago and triggered the onset of Younger Dryas (YD) cooling and widespread megafaunal extinctions and the demise of the Clovis archeological culture. Supporting signatures such as concentrated carbon spherules and enlogaes, magnetic grains and spherules, nanodiamonds, and Ir-enrichment have been reported, but over time their lack of reproducibility of results at different locations have brought into question the impact hypothesis. Among the impact signatures investigated by previous studies, only few researchers included Re and platinum group element (PGE: Os, Ir, Ru, Rh, Pt, and Pd) characteristic concentrations, and 187Os/188Os ratios for ET mixing in terrestrial materials. Less than 1% of ET materials can provide enriched PGE concentrations, such that PGE are a sensitive tool to identify ET input in terrestrial materials. Because of the large difference between chondritic and continental crust 187Os/188Os ratios, 0.127 and >1.4, respectively, the 187Os/188Os ratios are also highly sensitive indicators of an extraterrestrial component in terrestrial and marine sediments. In this study, we examine sediments associated with the YD from two reported sites in North America, Hall's Cave and the Freidken Archaeological site in Central Texas, using the PGE and Re geochemical approach to test the evidence of the extraterrestrial projectiles during Younger Dryas period. Our current data show at Hall's Cave the PGE concentrations and patterns do not confirm the presence of an elevated meteoritic contribution. However, the 187Os/188Os depth profile shows a sudden 187Os/188Os decrease from 2.28 2.45 to 1.64 at the YD boundary layer, consistent with an increase in material derived from ET projectiles with chondritic 187Os/188Os ratios contaminating the Earth surface at the time of the YD extinction. Additional samples from the YD boundary at the

  9. Complete Host Range Testing on Common Reed with Potential Biological Control Agents and Investigation into Biological Control for Flowering Rush

    Science.gov (United States)

    2016-07-01

    invasive and a threat to biodiversity (Wapshere 1990; Marks et al. 1994; Tewksbury et al. 2002). Only in the last century did P. australis start to...In 2015, haplotype I was added in a similar experiment. 1.1.2 Objectives The objectives of this research were to test the oviposition preference...A., and C. G. Eckert, 2005. Interaction between founder effect and selection during biological invasion in an aquatic plant. Evolution 59:1900–1913

  10. Superallowed 0+→0+ nuclear β decays: A critical survey with tests of the conserved vector current hypothesis and the standard model

    International Nuclear Information System (INIS)

    Hardy, J.C.; Towner, I.S.

    2005-01-01

    A complete and critical survey is presented of all half-life, decay-energy, and branching-ratio measurements related to 20 superallowed 0 + →0 + decays; no measurements are ignored, although some are rejected for cause and others updated. A new calculation of the statistical rate function f is described and experimental ft values determined. The associated theoretical corrections needed to convert these results into 'corrected' Ft values are discussed, and careful attention is paid to the origin and magnitude of their uncertainties. As an exacting confirmation of the conserved vector current hypothesis, the corrected Ft values are seen to be constant to three parts in 10 4 . These data are also used to set a new limit on any possible scalar interaction (assuming maximum parity violation) of C S /C V =-(0.00005±0.00130). The average Ft value obtained from the survey, when combined with the muon lifetime, yields the up-down quark-mixing element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, V ud =0.9738±0.0004, and the unitarity test on the top row of the matrix becomes vertical bar V ud vertical bar 2 + vertical bar V us vertical bar 2 + vertical bar V ub vertical bar 2 =0.9966±0.0014 using the Particle Data Group's currently recommended values for V us and V ub . If V us comes instead from two recent results on K e3 decay, the unitarity sum becomes 0.9996(11). Either result can be expressed in terms of the possible existence of right-hand currents. Finally, we discuss the priorities for future theoretical and experimental work with the goal of making the CKM unitarity test more definitive

  11. Testing the stress-gradient hypothesis at the roof of the world: effects of the cushion plant Thylacospermum caespitosum on species assemblages.

    Directory of Open Access Journals (Sweden)

    Miroslav Dvorský

    Full Text Available Many cushion plants ameliorate the harsh environment they inhabit in alpine ecosystems and act as nurse plants, with significantly more species growing within their canopy than outside. These facilitative interactions seem to increase with the abiotic stress, thus supporting the stress-gradient hypothesis. We tested this prediction by exploring the association pattern of vascular plants with the dominant cushion plant Thylacospermum caespitosum (Caryophyllaceae in the arid Trans-Himalaya, where vascular plants occur at one of the highest worldwide elevational limits. We compared plant composition between 1112 pair-plots placed both inside cushions and in surrounding open areas, in communities from cold steppes to subnival zones along two elevational gradients (East Karakoram: 4850-5250 m and Little Tibet: 5350-5850 m. We used PERMANOVA to assess differences in species composition, Friedman-based permutation tests to determine individual species habitat preferences, species-area curves to assess whether interactions are size-dependent and competitive intensity and importance indices to evaluate plant-plant interactions. No indications for net facilitation were found along the elevation gradients. The open areas were not only richer in species, but not a single species preferred to grow exclusively inside cushions, while 39-60% of 56 species detected had a significant preference for the habitat outside cushions. Across the entire elevation range of T. caespitosum, the number and abundance of species were greater outside cushions, suggesting that competitive rather than facilitative interactions prevail. This was supported by lower soil nutrient contents inside cushions, indicating a resource preemption, and little thermal amelioration at the extreme end of the elevational gradient. We attribute the negative associations to competition for limited resources, a strong environmental filter in arid high-mountain environment selecting the stress

  12. Cosmo Cassette: A Microfluidic Microgravity Microbial System For Synthetic Biology Unit Tests and Satellite Missions

    Science.gov (United States)

    Berliner, Aaron J.

    2013-01-01

    Although methods in the design-build-test life cycle of the synthetic biology field have grown rapidly, the expansion has been non-uniform. The design and build stages in development have seen innovations in the form of biological CAD and more efficient means for building DNA, RNA, and other biological constructs. The testing phase of the cycle remains in need of innovation. Presented will be both a theoretical abstraction of biological measurement and a practical demonstration of a microfluidics-based platform for characterizing synthetic biological phenomena. Such a platform demonstrates a design of additive manufacturing (3D printing) for construction of a microbial fuel cell (MFC) to be used in experiments carried out in space. First, the biocompatibility of the polypropylene chassis will be demonstrated. The novel MFCs will be cheaper, and faster to make and iterate through designs. The novel design will contain a manifold switchingdistribution system and an integrated in-chip set of reagent reservoirs fabricated via 3D printing. The automated nature of the 3D printing yields itself to higher resolution switching valves and leads to smaller sized payloads, lower cost, reduced power and a standardized platform for synthetic biology unit tests on Earth and in space. It will be demonstrated that the application of unit testing in synthetic biology will lead to the automatic construction and validation of desired constructs. Unit testing methodologies offer benefits of preemptive problem identification, change of facility, simplicity of integration, ease of documentation, and separation of interface from implementation, and automated design.

  13. Sensitivity of palaeo-ice-stream retreat patterns to ice-ocean interactions and topography: a test of the marine ice sheet instability hypothesis

    Science.gov (United States)

    Jamieson, S.; Vieli, A.; Livingstone, S. J.; O'Cofaigh, C.; Stokes, C. R.; Hillenbrand, C.

    2011-12-01

    The aim is to understand the long-term controls on marine ice stream retreat. Short-term observations combined with modelling are helping decipher the controls driving contemporary mass loss via dynamic thinning and grounding-line retreat. However, ice-stream response times are likely to be longer than the timescales for which contemporary observations are available. We therefore focus on century to millenial timescales by investigating the retreat of Marguerite Bay palaeo-ice stream in Antarctica after the LGM. Our approach is to use high-resolution mapping of glacial landforms on the sea floor to constrain a numerical ice stream model. Mapped positions of grounding-zone wedges indicate that the palaeo-ice stream paused multiple times during its rapid retreat over a bed that deepens inland. The geomorphic record not only questions the marine ice sheet instability hypothesis but also provides geometrical and dynamical constraints for retreat experiments using numerical ice stream models. To understand the controls on the retreat pattern in Marguerite Bay, we test the sensitivity of the ice stream to a range of forcing regimes using a 1-dimensional numerical flow-line model that incorporates basal, lateral and longitudinal stresses and a self-refining grid scheme. Ice-ocean interactions are incorporated via a fixed-length ice shelf, the inclusion of an ice-ocean boundary condition and the calculation of ocean-driven melt. We test modelled retreat sensitivity to a range of external forcing patterns including sea-level, temperature, accumulation and ocean-driven melt. In addition, the importance of the topographic setting of the ice drainage basin is also examined. We find that the modelled ice stream naturally re-creates the pauses observed in the geomorphic record and that the pattern of palaeo-grounding-line retreat in Marguerite Bay can only be achieved within the chronological timeframe by including ocean-driven melt. Sensitivity tests indicate that the

  14. Major depression in China-to-US immigrants and US-born Chinese Americans: testing a hypothesis from culture-gene co-evolutionary theory of mental disorders.

    Science.gov (United States)

    Tan, Tony Xing

    2014-01-01

    In this study, the culture-gene co-evolutionary theory of mental disorders was used to test the hypothesis that major depression was less prevalent in China-to-US immigrants who migrated to the US as adults than in US-born adult Chinese Americans. Data from the Collaborative Psychiatric Epidemiology Surveys (CPES) were extracted for secondary data analyses on the rates of major depression disorder (MDD) and major depressive episode (MDE) in the two groups. Findings showed that for life time MDD, the rates for China-to-US immigrant and US-born Chinese were 5.3% and 7.9% for men and 8.5% and 33.1% for women. For 12-month MDD, the corresponding rates were 2.2% and 3.4% for men, and 4.7% and 12.6% for women. For life time MDE, the corresponding rates were 6.8% and 8.8% for men; for women the rates were 8.5% and 33.1%. For 12-month MDE, the rates were 2.2% and 4.4% for men; the rates were 4.7% and 12.6% for women. Controlling for age, education level, income, BMI, marital status, and income-to-needs ratio, China-to-US immigrant women remained less likely to have life time major depression than US-born Chinese American women. While the study has the strength of utilizing nationally representative datasets, the approach is limited as the data sources lack the capacity to investigate how the strength of connection with the collectivist culture might be related to major depression in the immigrant group. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Income inequality and self-rated health in Stockholm, Sweden: a test of the 'income inequality hypothesis' on two levels of aggregation.

    Science.gov (United States)

    Rostila, Mikael; Kölegård, Maria L; Fritzell, Johan

    2012-04-01

    The number of studies analysing income inequality and health are voluminous. However, when empirically testing the income inequality hypothesis, the level of aggregation could be crucial for whether we find an association or not and for the mechanisms we believe are active. This study hence investigates: (1) the two-year lagged effect by income inequality on health at two levels of aggregation; municipalities and neighbourhoods in Sweden; (2) whether spending on social goods accounts for the association between income inequality and health; (3) the effect by income inequality among the affluent and the disadvantaged in municipalities and neighbourhoods, respectively. The empirical data is based on a Swedish public health survey in 2002 and includes residents of Stockholm aged 18-84 years. The sample consists of 28,092 individuals nested within 22 municipalities and 709 neighbourhoods in the county of Stockholm with a non-response rate of 37 percent. A total population register (HSIA) is further used for the construction of contextual-level indicators. Primary method used is multi-level logistic regression. The findings indicate a moderate effect by high and very high income inequality on self-rated poor health at the municipality-level. The association, however, ceases after adjustment for spending on social goods. No detrimental effect by income inequality on self-rated health at the neighbourhood-level is found. The results further suggest that poor individuals residing in high inequality neighbourhoods do not have poorer health than those residing in low inequality contexts while high inequality is most deleterious for poor individuals at the municipality-level. In sum, the findings suggest that reduced spending on social goods could account for the association between income inequality and health at the municipality-level. The contrasting findings at the neighbourhood- and municipality-level indicate that it is important to consider the level of aggregation

  16. Statistical analysis of water-quality data containing multiple detection limits II: S-language software for nonparametric distribution modeling and hypothesis testing

    Science.gov (United States)

    Lee, L.; Helsel, D.

    2007-01-01

    Analysis of low concentrations of trace contaminants in environmental media often results in left-censored data that are below some limit of analytical precision. Interpretation of values becomes complicated when there are multiple detection limits in the data-perhaps as a result of changing analytical precision over time. Parametric and semi-parametric methods, such as maximum likelihood estimation and robust regression on order statistics, can be employed to model distributions of multiply censored data and provide estimates of summary statistics. However, these methods are based on assumptions about the underlying distribution of data. Nonparametric methods provide an alternative that does not require such assumptions. A standard nonparametric method for estimating summary statistics of multiply-censored data is the Kaplan-Meier (K-M) method. This method has seen widespread usage in the medical sciences within a general framework termed "survival analysis" where it is employed with right-censored time-to-failure data. However, K-M methods are equally valid for the left-censored data common in the geosciences. Our S-language software provides an analytical framework based on K-M methods that is tailored to the needs of the earth and environmental sciences community. This includes routines for the generation of empirical cumulative distribution functions, prediction or exceedance probabilities, and related confidence limits computation. Additionally, our software contains K-M-based routines for nonparametric hypothesis testing among an unlimited number of grouping variables. A primary characteristic of K-M methods is that they do not perform extrapolation and interpolation. Thus, these routines cannot be used to model statistics beyond the observed data range or when linear interpolation is desired. For such applications, the aforementioned parametric and semi-parametric methods must be used.

  17. Neurocognitive enhancement in older adults: comparison of three cognitive training tasks to test a hypothesis of training transfer in brain connectivity.

    Science.gov (United States)

    Strenziok, Maren; Parasuraman, Raja; Clarke, Ellen; Cisler, Dean S; Thompson, James C; Greenwood, Pamela M

    2014-01-15

    The ultimate goal of cognitive enhancement as an intervention for age-related cognitive decline is transfer to everyday cognitive functioning. Development of training methods that transfer broadly to untrained cognitive tasks (far transfer) requires understanding of the neural bases of training and far transfer effects. We used cognitive training to test the hypothesis that far transfer is associated with altered attentional control demands mediated by the dorsal attention network and trained sensory cortex. In an exploratory study, we randomly assigned 42 healthy older adults to six weeks of training on Brain Fitness (BF-auditory perception), Space Fortress (SF-visuomotor/working memory), or Rise of Nations (RON-strategic reasoning). Before and after training, cognitive performance, diffusion-derived white matter integrity, and functional connectivity of the superior parietal cortex (SPC) were assessed. We found the strongest effects from BF training, which transferred to everyday problem solving and reasoning and selectively changed integrity of occipito-temporal white matter associated with improvement on untrained everyday problem solving. These results show that cognitive gain from auditory perception training depends on heightened white matter integrity in the ventral attention network. In BF and SF (which also transferred positively), a decrease in functional connectivity between SPC and inferior temporal lobe (ITL) was observed compared to RON-which did not transfer to untrained cognitive function. These findings highlight the importance for cognitive training of top-down control of sensory processing by the dorsal attention network. Altered brain connectivity - observed in the two training tasks that showed far transfer effects - may be a marker for training success. © 2013 Elsevier Inc. All rights reserved.

  18. Combining local lithofacies and global geochemical signals to test the acidification hypothesis for the onset of Oceanic Anoxic Event 2 in the U.S. Western Interior Basin

    Science.gov (United States)

    Jones, M. M.; Sageman, B. B.; Selby, D. S.; Oakes, R. L.; Bralower, T. J.; Parker, A. L.; Leckie, R. M.; Sepulveda, J.

    2015-12-01

    Strata preserving Oceanic Anoxic Event 2 (OAE2), which span the Cenomanian-Turonian (C/T; Late Cretaceous), exhibit evidence of widespread anoxia, a major perturbation to the global carbon cycle, and increased biotic turnover rates. It has been hypothesized that a major volcanic (LIP) eruption, increased CO2 levels, and significant climate warming triggered the event. Recently, OAE2 has also been cited as a potential example of ocean acidification in Earth history and therefore has potential to offer predictive insights on impacts of increasing modern pCO2 levels. As part of an effort to test this hypothesis, the 131-m Smoky Hollow #1 (SH-1) core was drilled near Big Water, Utah during the summer of 2014. The core recovered an expanded stratigraphic record of OAE2 from the mud-rich western margin of the Western Interior Seaway. A high-resolution stable carbon isotope record from bulk organic carbon (δ13Corg) indicates near-continuous preservation of OAE2 with a sustained +2.5‰ excursion that is over 5 times the thickness of the same excursion at the C/T GSSP in Pueblo, Colorado. Notably, this record is characterized by a 1-m thick carbonate-barren interval at the δ13C excursion's onset. This may indicate an episode of ocean acidification driving suppressed carbonate sedimentation or carbonate dissolution. An alternative interpretation is that variations in carbonate concentrations are unrelated to changes in ocean chemistry and are instead driven by changes in local sedimentation patterns (e.g. transgressive-regressive parasequences). To test these hypotheses, a regional lithostratigraphic correlation to the nearshore Cottonwood Canyon section is constructed to assess whether prograding sandy parasequences may have altered carbonate sedimentation rates at the SH-1 locality. Initial osmium and δ13C chemostratigraphies are also developed to constrain the timing of perturbations in global geochemical cycles at the initiation of OAE2, including the onset of large

  19. Physiopathological Hypothesis of Cellulite

    Science.gov (United States)

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

    2009-01-01

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

  20. Life Origination Hydrate Hypothesis (LOH-Hypothesis).

    Science.gov (United States)

    Ostrovskii, Victor; Kadyshevich, Elena

    2012-01-04

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

  1. Life Origination Hydrate Hypothesis (LOH-Hypothesis

    Directory of Open Access Journals (Sweden)

    Victor Ostrovskii

    2012-01-01

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

  2. 77 FR 26162 - Amendments to Sterility Test Requirements for Biological Products

    Science.gov (United States)

    2012-05-03

    ... obtained by analysis of the same sample under a variety of normal test conditions, such as different... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration 21 CFR Parts 600, 610, and 680 [Docket No. FDA-2011-N-0080] Amendments to Sterility Test Requirements for Biological Products...

  3. Testing the Snake-Detection hypothesis : Larger early posterior negativity in humans to pictures of snakes than to pictures of other reptiles, spiders and slugs

    NARCIS (Netherlands)

    van Strien, Jan W.; Franken, Ingmar H A; Huijding, Jorg

    2014-01-01

    According to the snake detection hypothesis (Isbell, 2006), fear specifically of snakes may have pushed evolutionary changes in the primate visual system allowing pre-attentional visual detection of fearful stimuli. A previous study demonstrated that snake pictures, when compared to spiders or bird

  4. Growth-Related Neural Reorganization and the Autism Phenotype: A Test of the Hypothesis that Altered Brain Growth Leads to Altered Connectivity

    Science.gov (United States)

    Lewis, John D.; Elman, Jeffrey L.

    2008-01-01

    Theoretical considerations, and findings from computational modeling, comparative neuroanatomy and developmental neuroscience, motivate the hypothesis that a deviant brain growth trajectory will lead to deviant patterns of change in cortico-cortical connectivity. Differences in brain size during development will alter the relative cost and…

  5. Reactions to Unfavorable Evaluations of the Self as a Function of Acceptance of Disability: A Test of Dembo, Leviton, And Wright's Misfortune Hypothesis

    Science.gov (United States)

    Grand, Sheldon A.

    1972-01-01

    Based on Dembo et al. (1956), it was predicted that in comparing high acceptors of their disability with low acceptors, the latter would (a) rate a non-disabled negative evaluator as more likeable, (b) perceive themselves as more similar to him, and (c) suffer more as a result of exposure to him. The hypothesis was confirmed. (Author/BY)

  6. An Overall Comparison of Small Molecules and Large Biologics in ADME Testing

    Directory of Open Access Journals (Sweden)

    Hong Wan

    2016-03-01

    Full Text Available Biologics mainly monoclonal antibodies (mAbs and antibody-drug conjugates (ADCs as new therapeutics are becoming increasingly important biotherapeutics. This review is intended to provide an overall comparison between small molecules (SMs and biologics or large molecules (LMs concerning drug metabolism and pharmacokinetic (DMPK or associated with absorption, distribution, metabolism and elimination (ADME testing from pharmaceutical industry drug discovery and development points of view, which will help design and conduct relevant ADME testing for biologics such as mAbs and ADCs. Recent advancements in the ADME for testing biologics and related bioanalytical methods are discussed with an emphasis on ADC drug development as an example to understand its complexity and challenges from extensive in vitro characterization to in vivo animal PK studies. General non-clinical safety evaluations of biologics in particular for ADC drugs are outlined including drug-drug interaction (DDI and metabolite/catabolite assessments. Regulatory guidance on the ADME testing and safety evaluations including immunogenicity as well as bioanalytical considerations are addressed for LMs. In addition, the preclinical and human PK data of two marked ADC drugs (ADCETRIS, SGN-35 and KADCYLA, T-DM1 as examples are briefly discussed with regard to PK considerations and PK/PD perspectives.

  7. Passive margin high altitude low relief surfaces: old or new? Testing the glacial/periglacial buzzsaw hypothesis on the landscape of Southern Norway.

    Science.gov (United States)

    Berthling, Ivar

    2015-04-01

    investigated on local scales. We test the periglacial 'buzzsaw' by spatial and temporal upscaling from current periglacial solifluction landforms and process rates. Berthling, I., and Etzelmüller, B., 2011, The concept of cryo-conditioning in landscape evolution: Quaternary Research, v. 75, no. 2, p. 378-384. French, H. M., 2007, The Periglacial Environment, John Wiley & Sons, 458 pp Gołędowski, B., Egholm, D. L., Nielsen, S. B., Clausen, O. R., and McGregor, E. D., 2013, Cenozoic erosion and flexural isostasy of Scandinavia: Journal of Geodynamics, v. 70, p. 49-57. LidmarBergstrom, K., Ollier, C. D., and Sulebak, J. R., 2000, Landforms and uplift history of southern Norway: Global and Planetary Change, v. 24, no. 3-4, p. 211-231. Nielsen, S. B., Gallagher, K., Leighton, C., Balling, N., Svenningsen, L., Jacobsen, B. H., Thomsen, E., Nielsen, O. B., Heilmann-Clausen, C., Egholm, D. L., Summerfield, M. A., Clausen, O. R., Piotrowski, J. A., Thorsen, M. R., Huuse, M., Abrahamsen, N., King, C., and Lykke-Andersen, H., 2009, The evolution of western Scandinavian topography: A review of Neogene uplift versus the ICE (isostasy-climate-erosion) hypothesis: Journal of Geodynamics, v. 47, no. 2-3, p. 72-95.

  8. 5-HTP hypothesis of schizophrenia.

    Science.gov (United States)

    Fukuda, K

    2014-01-01

    To pose a new hypothesis of schizophrenia that affirms and unifies conventional hypotheses. Outside the brain, there are 5-HTP-containing argyrophil cells that have tryptophan hydroxylase 1 without l-aromatic amino acid decarboxylase. Monoamine oxidase in the liver and lung metabolize 5-HT, rather than 5-HTP, and 5-HTP freely crosses the blood-brain barrier, converting to 5-HT in the brain. Therefore I postulate that hyperfunction of 5-HTP-containing argyrophil cells may be a cause of schizophrenia. I investigate the consistency of this hypothesis with other hypotheses using a deductive method. Overactive 5-HTP-containing argyrophil cells produce excess amounts of 5-HTP. Abundant 5-HTP increases 5-HT within the brain (linking to the 5-HT hypothesis), and leads to negative feedback of 5-HT synthesis at the rate-limiting step catalysed by tryptophan hydroxylase 2. Owing to this negative feedback, brain tryptophan is further metabolized via the kynurenine pathway. Increased kynurenic acid contributes to deficiencies of glutamate function and dopamine activity, known causes of schizophrenia. The 5-HTP hypothesis affirms conventional hypotheses, as the metabolic condition caused by acceleration of tryptophan hydroxylase 1 and suppression of tryptophan hydroxylase 2, activates both 5-HT and kynurenic acid. In order to empirically test the theory, it will be useful to monitor serum 5-HTP and match it to different phases of schizophrenia. This hypothesis may signal a new era with schizophrenia treated as a brain-gut interaction. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. An investigation on impacts of scheduling configurations on Mississippi biology subject area testing

    Science.gov (United States)

    Marchette, Frances Lenora

    The purpose of this mixed modal study was to compare the results of Biology Subject Area mean scores of students on a 4 x 4 block schedule, A/B block schedule, and traditional year-long schedule for 1A to 5A size schools. This study also reviewed the data to determine if minority or gender issues might influence the test results. Interviews with administrators and teachers were conducted about the type of schedule configuration they use and the influence that the schedule has on student academic performance on the Biology Subject Area Test. Additionally, this research further explored whether schedule configurations allow sufficient time for students to construct knowledge. This study is important to schools, teachers, and administrators because it can assist them in considering the impacts that different types of class schedules have on student performance and if ethnic or gender issues are influencing testing results. This study used the causal-comparative method for the quantitative portion of the study and constant comparative method for the qualitative portion to explore the relationship of school schedules on student academic achievement on the Mississippi Biology Subject Area Test. The aggregate means of selected student scores indicate that the Mississippi Biology Subject Area Test as a measure of student performance reveals no significant difference on student achievement for the three school schedule configurations. The data were adjusted for initial differences of gender, minority, and school size on the three schedule configurations. The results suggest that schools may employ various schedule configurations and expect student performance on the Mississippi Biology Subject Area Test to be unaffected. However, many areas of concern were identified in the interviews that might impact on school learning environments. These concerns relate to effective classroom management, the active involvement of students in learning, the adequacy of teacher education

  10. Biology

    Indian Academy of Sciences (India)

    I am particularly happy that the Academy is bringing out this document by Professor M S. Valiathan on Ayurvedic Biology. It is an effort to place before the scientific community, especially that of India, the unique scientific opportunities that arise out of viewing Ayurveda from the perspective of contemporary science, its tools ...

  11. A Molecular–Structure Hypothesis

    Directory of Open Access Journals (Sweden)

    Jan C. A. Boeyens

    2010-11-01

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

  12. VIRAL TESTING USING BIOLOGICAL AND SEROLOGICAL ASSAY FOR MOST IMPORTANT VIRUSES TO PLUM

    Directory of Open Access Journals (Sweden)

    Catita Plopa

    2014-12-01

    Full Text Available Establishing an accurate diagnosis in terms of viral for propagation of fruit tree is very important, it represents the most effective method of protection against viruses. Based on these considerations the primary objective of this study is to detect viruses with the highest incidence in plum by biological and ELISA serological methods, to a number of 85 samples taken from 17 varieties. Serologic testing on DAS-ELISA diagnosed 3 positive samples to Plum pox virus (PPV, 2 positives sample to Prunus necrotic ring spot virus (PNRSV and one positive sample to Prune dwarf virus (PDV. There were not positive samples to Apple chlorotic leaf spot virus (ACLSV. The tests conducted on woody indicator plants by grafting on protect conditions and after 3-24 months assured of diagnosis for PPV, PDV, PNRSV and ACLSV viruses. The biological indicators: ‘GF 305’, ‘Tuleu dulce’ and ‘Vânăt de Italia’, have shown symptoms for PNRSV for two samples.On biological indicator ‘Vânăt de Italia’ and ‘Tuleu dulce’ not appeared symptoms for ‘Centenar’variety tested for PPV, although the symptoms were obvious on ‘GF 305’ indicator, but viral infection was confirmed by ELISA test. Symptoms that indicate the presence of PDV occurred by ‘Vânăt de Italia’ biological indicator.

  13. Too much food may cause reduced growth of blue mussels (Mytilus edulis) – Test of hypothesis and new ‘high Chl a BEG-model’

    DEFF Research Database (Denmark)

    Larsen, Poul S.; Lüskow, Florian; Riisgård, Hans Ulrik

    2018-01-01

    Growth of the blue mussel (Mytilus edulis) is closely related to the biomass of phytoplankton (expressed as concentration of chlorophyll a, Chl a), but the effect of too much food in eutrophicated areas has so far been overlooked. The hypothesis addressed in the present study suggests that high C...... the effect of Chl a, but the present study shows that too much food may cause reduced growth of mussels in eutrophicated marine areas regardless of high or moderate salinity above about 10 psu.......Growth of the blue mussel (Mytilus edulis) is closely related to the biomass of phytoplankton (expressed as concentration of chlorophyll a, Chl a), but the effect of too much food in eutrophicated areas has so far been overlooked. The hypothesis addressed in the present study suggests that high Chl...... in which the growth of mussels in net bags was measured along a Chl a gradient are presented. Finally, we discuss the phenomenon of reduced growth of mussels in eutrophicated areas versus a possible impact of low salinity. It is concluded that it is difficult to separate the effect of salinity from...

  14. Tests of biological activity of metabolites from Penicillium expansum (Link Thom various isolates

    Directory of Open Access Journals (Sweden)

    Halina Borecka

    2013-12-01

    Full Text Available Aqrobacterium tumefaciens and cucumber, mustard and linseeds were compared as test organisms for evaluation of the biological activity of patulin. It was found that the reaction of cucumber seeds and linseed to the patulin concentrations was more pronounced than that of mustard and Aqrobacterium tumefaciens. The activity of metabolites produced by Penicillium expansum was investigated with the use of cucumber seeds. As measure of activity served the percentage of radicule growth inhibition was compared with the growth in control seeds. The biological activity of the metabolites was specific for the isolates, those from apples being more active. Thirty two isolates from pears and 34 from apples were examined.

  15. The Qualitative Expectations Hypothesis

    DEFF Research Database (Denmark)

    Frydman, Roman; Johansen, Søren; Rahbek, Anders

    2017-01-01

    We introduce the Qualitative Expectations Hypothesis (QEH) as a new approach to modeling macroeconomic and financial outcomes. Building on John Muth's seminal insight underpinning the Rational Expectations Hypothesis (REH), QEH represents the market's forecasts to be consistent with the predictions...... of an economistís model. However, by assuming that outcomes lie within stochastic intervals, QEH, unlike REH, recognizes the ambiguity faced by an economist and market participants alike. Moreover, QEH leaves the model open to ambiguity by not specifying a mechanism determining specific values that outcomes take...

  16. The Qualitative Expectations Hypothesis

    DEFF Research Database (Denmark)

    Frydman, Roman; Johansen, Søren; Rahbek, Anders

    We introduce the Qualitative Expectations Hypothesis (QEH) as a new approach to modeling macroeconomic and financial outcomes. Building on John Muth's seminal insight underpinning the Rational Expectations Hypothesis (REH), QEH represents the market's forecasts to be consistent with the predictions...... of an economist's model. However, by assuming that outcomes lie within stochastic intervals, QEH, unlike REH, recognizes the ambiguity faced by an economist and market participants alike. Moreover, QEH leaves the model open to ambiguity by not specifying a mechanism determining specific values that outcomes take...

  17. Covariance Association Test (CVAT) Identifies Genetic Markers Associated with Schizophrenia in Functionally Associated Biological Processes

    DEFF Research Database (Denmark)

    Rohde, Palle Duun; Demontis, Ditte; Castro Dias Cuyabano, Beatriz

    2016-01-01

    power to detect genetic markers with small effects. Instead, aggregating genetic markers based on biological information might increase the power to identify sets of genetic markers of etiological significance. Several set test methods have been proposed: Here we propose a new set test derived from......Schizophrenia is a psychiatric disorder with large personal and social costs, and understanding the genetic etiology is important. Such knowledge can be obtained by testing the association between a disease phenotype and individual genetic markers; however, such single-marker methods have limited...

  18. Biology, host specificity tests, and risk assessment of the sawfly Heteroperreyia hubrichi, a potential biological control agent of Schinus terebinthifolius in Hawaii

    Science.gov (United States)

    Abstract. Heteroperreyia hubrichi Malaise (Hymenoptera: Pergidae), a foliage feeding sawfly of Schinus terebinthifolius Raddi (Sapindales: Anacardiaceae), was studied to assess its suitability as a classical biological control agent of this invasive weed in Hawaii. Nochoice host-specificity tests we...

  19. The Uptake and Fate of Vanadyl Ion in Ascidian Blood Cells and A Detailed Hypothesis for the Mechanism and Location of Biological Vanadium Reduction: A Visible and X-Ray Absorption Spectroscopic Study

    Science.gov (United States)

    Frank, Patrick; Carlson, Elaine J.; Carlson, Robert M. K.; Hedman, Britt; Hodgson, Keith O.

    2010-01-01

    Vanadium K-edge x-ray absorption spectroscopy (XAS) has been used to track the uptake and fate of VO2+ ion in blood cells from Ascidia ceratodes, following exposure to dithiothreitol (DTT) or to DTT plus VO2+. The full range of endogenous vanadium was queried by fitting the XAS of blood cells with the XAS spectra of model vanadium complexes. In cells exposed only to DTT, ~0.4% of a new V(III) species was found in a site similar to Na[V(edta)(H2O)]. With exposure to DTT and VO2+, average intracellular [VO(aq)]2+ increased from 3% to 5%, and 6% of a new complexed form of vanadyl ion appeared evidencing a ligand array similar to [VO(edta)]2−. At the same time, the relative ratio of blood cell [V(H2O)6]3+ increased at the expense of [V(H2O)5(SO4)]+ in a manner consistent with a significant increase in endogenous acidity. In new UV/visible experiments, VO2+ could be reduced to 7-coordinate [V(nta)(H2O)3] or [V(nta)(ida)]2−with cysteine methyl ester in pH 6.5 solution. Ascorbate reduced [VO(edta)]2− to 7-coordinate [V(edta)(H2O)]−, while [VO(trdta)]2− was unreactive. These results corroborate the finding that the reductive EMF of VO2+ is increased by the availability of a 7-coordinate V(III) product. Finally a new and complete hypothesis is proposed for an ascidian vanadate reductase. The structure of the enzyme active site, the vanadate-vanadyl-vanadic reduction mechanism, the cellular locale, and elements of the regulatory machinery governing the biological reduction of vanadate and vanadyl ion by ascidians are all predicted. Together these constitute the new field of vanadium redox enzymology. PMID:18234345

  20. The Lehman Sisters Hypothesis

    NARCIS (Netherlands)

    I.P. van Staveren (Irene)

    2014-01-01

    markdownabstract__Abstract__ This article explores the Lehman Sisters Hypothesis. It reviews empirical literature about gender differences in behavioral, experimental, and neuro-economics as well as in other fields of behavioral research. It discusses gender differences along three dimensions of