Difference between the vocalizations of two sister species of pigeons explained in dynamical terms.

PubMed

Alonso, R Gogui; Kopuchian, Cecilia; Amador, Ana; Suarez, Maria de Los Angeles; Tubaro, Pablo L; Mindlin, Gabriel B

2016-05-01

Vocal communication is an unique example, where the nonlinear nature of the periphery can give rise to complex sounds even when driven by simple neural instructions. In this work we studied the case of two close-related bird species, Patagioenas maculosa and Patagioenas picazuro, whose vocalizations differ only in the timbre. The temporal modulation of the fundamental frequency is similar in both cases, differing only in the existence of sidebands around the fundamental frequency in the P. maculosa. We tested the hypothesis that the qualitative difference between these vocalizations lies in the nonlinear nature of the syrinx. In particular, we propose that the roughness of maculosa's vocalizations is due to an asymmetry between the right and left vibratory membranes, whose nonlinear dynamics generate the sound. To test the hypothesis, we generated a biomechanical model for vocal production with an asymmetric parameter Q with which we can control the level of asymmetry between these membranes. Using this model we generated synthetic vocalizations with the principal acoustic features of both species. In addition, we confirmed the anatomical predictions by making post mortem inspection of the syrinxes, showing that the species with tonal song (picazuro) has a more symmetrical pair of membranes compared to maculosa.

Difference between the vocalizations of two sister species of pigeons explained in dynamical terms

PubMed Central

Alonso, R. Gogui; Kopuchian, Cecilia; Amador, Ana; de los Angeles Suarez, Maria; Tubaro, Pablo L.; Mindlin, Gabriel B.

2016-01-01

Vocal communication is a unique example where the nonlinear nature of the periphery can give rise to complex sounds even when driven by simple neural instructions. In this work we studied the case of two close-related bird species, Patagioenas maculosa and Patagioenas picazuro, whose vocalizations differ only in the timbre. The temporal modulation of the fundamental frequency is similar in both cases, differing only in the existence of sidebands around the fundamental frequency in the Patagioenas maculosa. We tested the hypothesis that the qualitative difference between these vocalizations lies in the nonlinear nature of the syrinx. In particular, we propose that the roughness of maculosa's vocalizations is due to an asymmetry between the right and left vibratory membranes, whose nonlinear dynamics generate the sound. To test the hypothesis, we generated a biomechanical model for vocal production with an asymmetric parameter Q with which we can control the level of asymmetry between these membranes. Using this model we generated synthetic vocalizations with the principal acoustic features of both species. In addition, we confirmed the anatomical predictions by making post-mortem inspection of the syrinxes, showing that the species with tonal song (picazuro) has a more symmetrical pair of membranes compared to maculosa. PMID:27033354

Social Engagement and Adaptive Functioning during Early Childhood: Identifying and Distinguishing among Subgroups Differing with Regard to Social Engagement

ERIC Educational Resources Information Center

Vaughn, Brian E.; Santos, António J.; Monteiro, Ligia; Shin, Nana; Daniel, João R.; Krzysik, Lisa; Pinto, Alexandra

2016-01-01

This study tested the hypothesis that social engagement (SE) with peers is a fundamental aspect of social competence during early childhood. Relations between SE and a set of previously validated social competence indicators, as well as additional variables derived from observation and sociometric interviews were assessed using both…

Implicit Acquisition of Grammars with Crossed and Nested Non-Adjacent Dependencies: Investigating the Push-Down Stack Model

ERIC Educational Resources Information Center

Udden, Julia; Ingvar, Martin; Hagoort, Peter; Petersson, Karl M.

2012-01-01

A recent hypothesis in empirical brain research on language is that the fundamental difference between animal and human communication systems is captured by the distinction between finite-state and more complex phrase-structure grammars, such as context-free and context-sensitive grammars. However, the relevance of this distinction for the study…

The Weaker Language in Early Child Bilingualism: Acquiring a First Language as a Second Language?

ERIC Educational Resources Information Center

Meisel, Jurgen M.

2007-01-01

Past research demonstrates that first language (L1)-like competence in each language can be attained in simultaneous acquisition of bilingualism by mere exposure to the target languages. The question is whether this is also true for the "weaker" language (WL). The WL hypothesis claims that the WL differs fundamentally from monolingual L1 and…

Processing of Tense Morphology and Filler-Gap Dependencies by Chinese Second Language Speakers of English

ERIC Educational Resources Information Center

Dong, Zhiyin Renee

2014-01-01

There is an ongoing debate in the field of Second Language Acquisition concerning whether a fundamental difference exists between the native language (L1) and adult second language (L2) online processing of syntax and morpho-syntax. The Shallow Structure Hypothesis (SSH) (Clahsen and Felser, 2006a, b) states that L2 online parsing is qualitatively…

A brief history of autism, the autism/vaccine hypothesis and a review of the genetic basis of autism spectrum disorders.

PubMed

Blake, Jerome; Hoyme, H Eugene; Crotwell, Patricia L

2013-01-01

Autism spectrum disorders (ASD) represent a common spectrum of developmental disabilities, sharing deficits in social interactions, communication and restricted interests or repetitive behaviors with difficult transitions. In this article, we review the history of the identification and classification of autism and the origin of the now widely-debunked autism/vaccine hypothesis. The differences between syndromal (complex) and non-syndromal (essential) autism are described and illustrated with case descriptions where appropriate. Finally, the evidence that autism is fundamentally a genetic disease is discussed, including family studies, the role of DNA copy number variation and known single gene mutations.

The Failed Feminist Challenge to `Fundamental Epistemology'

NASA Astrophysics Data System (ADS)

Pinnick, Cassandra L.

Despite volumes written in the name of the new and fundamental feminist project in philosophy of science, and conclusions drawn on the strength of the hypothesis that the feminist project will boost progress toward cognitive aims associated with science and rationality (and, one might add, policy decisions enacted in the name of these aims), the whole rationale for the project remains (after 20 years, plus) wholly unsubstantiated. We must remain agnostic about its evidentiary merits or demerits. This is because we are without evidence to test the hypothesis: certainly, we have no data that would test the strength of the hypothesis as asserting a causal relationship between women and cognitive ends. Thus, any self-respecting epistemologist who places a premium on evidence-driven belief and justification ought not to accept the hypothesis. By extension, there is no reasoned basis to draw any definitive conclusion about the project itself. No matter how self-evidently correct.

Physiopathological Hypothesis of Cellulite

PubMed Central

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

2009-01-01

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

System-theoretic Interpretation of the Mode Sensing Hypothesis

DTIC Science & Technology

2014-08-01

estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the...6. AUTHOR(S) Prof. Rafal Zbikowski Prof. Graham Taylor 5d. PROJECT NUMBER 5d. TASK NUMBER 5e. WORK UNIT NUMBER 7. PERFORMING...insect flight control has more recently been modelled. The approach that we adopt here differs from previous, related work in several fundamental

Method of constructing a fundamental equation of state based on a scaling hypothesis

NASA Astrophysics Data System (ADS)

Rykov, V. A.; Rykov, S. V.; Kudryavtseva, I. V.; Sverdlov, A. V.

2017-11-01

The work studies the issues associated with the construction of the equation of state (EOS) taking due account of substance behavior in the critical region and associated with the scaling theory of critical phenomena (ST). The authors have developed a new version of the scaling hypothesis; this approach uses the following: a) substance equation of state having a form of a Schofield-Litster-Ho linear model (LM) and b) the Benedek hypothesis. The Benedek hypothesis has found a similar behavior character for a number of properties (isochoric and isobaric heat capacities, isothermal compressibility coefficient) at critical and near-critical isochors in the vicinity of the critical point. A method is proposed to build the fundamental equation of state (FEOS) which satisfies the ST power laws. The FEOS building method is verified by building the equation of state for argon within the state parameters range: up to 1000 MPa in terms of pressure, and from 83.056 К to 13000 К in terms of temperature. The executed comparison with the fundamental equations of state of Stewart-Jacobsen (1989), of Kozlov at al (1996), of Tegeler-Span-Wagner (1999), of has shown that the FEOS describes the known experimental data with an essentially lower error.

Peripheral neuropathy may not be the only fundamental reason explaining increased sway in diabetic individuals.

PubMed

Bonnet, Cédrick T; Ray, Christopher

2011-08-01

Individuals with diabetic neuropathy sway more than control individuals while standing. This review specifically evaluated whether peripheral sensory neuropathy can be the only fundamental reason accounting for significant increased sway within this population. Twenty-six experimental articles were selected using MEDLINE and reference lists of relevant articles. The articles chosen investigated kinematic data of postural behaviour in controls and individuals with diabetic neuropathy during stance. Results of literature were compared with four expectations related to the peripheral sensory neuropathy fundamental hypothesis. Consistent with the peripheral sensory neuropathy hypothesis, the literature showed that individuals with diabetic neuropathy sway more than controls in quiet stance and even more so if their visual or vestibular systems were perturbed. Inconsistent with the hypothesis, individuals with diabetic neuropathy are more destabilised than controls in conditions altering sensation of the feet and legs (standing on a sway-referenced surface). The review showed that the peripheral sensory neuropathy hypothesis may not be the only fundamental cause accounting for significant increased postural sway in individuals with diabetic neuropathy. Visual impairments and changes in postural coordination may explain the divergence between expectations and results. In order to develop interventions aimed at improving postural control in individuals with diabetic neuropathy, scientific exploration of these new expectations should be detailed. Also at the practical level, the review discussed which additional sensory information - at the level of the hands and feet - may be more beneficial in individuals with diabetic neuropathy to reduce their postural sway. Copyright © 2011 Elsevier Ltd. All rights reserved.

A predictive approach to selecting the size of a clinical trial, based on subjective clinical opinion.

PubMed

Spiegelhalter, D J; Freedman, L S

1986-01-01

The 'textbook' approach to determining sample size in a clinical trial has some fundamental weaknesses which we discuss. We describe a new predictive method which takes account of prior clinical opinion about the treatment difference. The method adopts the point of clinical equivalence (determined by interviewing the clinical participants) as the null hypothesis. Decision rules at the end of the study are based on whether the interval estimate of the treatment difference (classical or Bayesian) includes the null hypothesis. The prior distribution is used to predict the probabilities of making the decisions to use one or other treatment or to reserve final judgement. It is recommended that sample size be chosen to control the predicted probability of the last of these decisions. An example is given from a multi-centre trial of superficial bladder cancer.

Can We Falsify the Consciousness-Causes-Collapse Hypothesis in Quantum Mechanics?

NASA Astrophysics Data System (ADS)

de Barros, J. Acacio; Oas, Gary

2017-10-01

In this paper we examine some proposals to disprove the hypothesis that the interaction between mind and matter causes the collapse of the wave function, showing that such proposals are fundamentally flawed. We then describe a general experimental setup retaining the key features of the ones examined, and show that even a more general case is inadequate to disprove the mind-matter collapse hypothesis. Finally, we use our setup provided to argue that, under some reasonable assumptions about consciousness, such hypothesis is unfalsifiable.

Testing fundamental ecological concepts with a Pythium-Prunus pathosystem

USDA-ARS?s Scientific Manuscript database

The study of plant-pathogen interactions has enabled tests of basic ecological concepts on plant community assembly (Janzen-Connell Hypothesis) and plant invasion (Enemy Release Hypothesis). We used a field experiment to (#1) test whether Pythium effects depended on host (seedling) density and/or d...

Modeling Cross-Situational Word–Referent Learning: Prior Questions

PubMed Central

Yu, Chen; Smith, Linda B.

2013-01-01

Both adults and young children possess powerful statistical computation capabilities—they can infer the referent of a word from highly ambiguous contexts involving many words and many referents by aggregating cross-situational statistical information across contexts. This ability has been explained by models of hypothesis testing and by models of associative learning. This article describes a series of simulation studies and analyses designed to understand the different learning mechanisms posited by the 2 classes of models and their relation to each other. Variants of a hypothesis-testing model and a simple or dumb associative mechanism were examined under different specifications of information selection, computation, and decision. Critically, these 3 components of the models interact in complex ways. The models illustrate a fundamental tradeoff between amount of data input and powerful computations: With the selection of more information, dumb associative models can mimic the powerful learning that is accomplished by hypothesis-testing models with fewer data. However, because of the interactions among the component parts of the models, the associative model can mimic various hypothesis-testing models, producing the same learning patterns but through different internal components. The simulations argue for the importance of a compositional approach to human statistical learning: the experimental decomposition of the processes that contribute to statistical learning in human learners and models with the internal components that can be evaluated independently and together. PMID:22229490

Water beetle tolerance to salinity and anionic composition and its relationship to habitat occupancy.

PubMed

Céspedes, V; Pallarés, S; Arribas, P; Millán, A; Velasco, J

2013-10-01

Water salinity and ionic composition are among the main environmental variables that constrain the fundamental niches of aquatic species, and accordingly, physiological tolerance to these factors constitutes a crucial part of the evolution, ecology, and biogeography of these organisms. The present study experimentally estimated the fundamental saline and anionic niches of adults of two pairs of congeneric saline beetle species that differ in habitat preference (lotic and lentic) in order to test the habitat constraint hypothesis. Osmotic and anionic realised niches were also estimated based on the field occurrences of adult beetle species using Outlying Mean Index analysis and their relationship with experimental tolerances. In the laboratory, all of the studied species showed a threshold response to increased salinity, displaying high survival times when exposed to low and intermediate conductivity levels. These results suggest that these species are not strictly halophilic, but that they are able to regulate both hyperosmotically and hypoosmotically. Anionic water composition had a significant effect on salinity tolerance at conductivity levels near their upper tolerance limits, with decreased species survival at elevated sulphate concentrations. Species occupying lentic habitats demonstrated higher salinity tolerance than their lotic congeners in agreement with the habitat constraint hypothesis. As expected, realised salinity niches were narrower than fundamental niches and corresponded to conditions near the upper tolerance limits of the species. These species are uncommon on freshwater-low conductivity habitats despite the fact that these conditions might be physiologically suitable for the adult life stage. Other factors, such as biotic interactions, could prevent their establishment at low salinities. Differences in the realised anionic niches of congeneric species could be partially explained by the varying habitat availability in the study area. Combining the experimental estimation of fundamental niches with realised field data niche estimates is a powerful method for understanding the main factors constraining species' distribution at multiple scales, which is a key issue when predicting species' ability to cope with global change. Copyright © 2013 Elsevier Ltd. All rights reserved.

Explorations in Statistics: Power

ERIC Educational Resources Information Center

Curran-Everett, Douglas

2010-01-01

Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This fifth installment of "Explorations in Statistics" revisits power, a concept fundamental to the test of a null hypothesis. Power is the probability that we reject the null hypothesis when it is false. Four…

What Constitutes Science and Scientific Evidence: Roles of Null Hypothesis Testing

ERIC Educational Resources Information Center

Chang, Mark

2017-01-01

We briefly discuss the philosophical basis of science, causality, and scientific evidence, by introducing the hidden but most fundamental principle of science: the similarity principle. The principle's use in scientific discovery is illustrated with Simpson's paradox and other examples. In discussing the value of null hypothesis statistical…

An Hypothesis-Driven, Molecular Phylogenetics Exercise for College Biology Students

ERIC Educational Resources Information Center

Parker, Joel D.; Ziemba, Robert E.; Cahan, Sara Helms; Rissing, Steven W.

2004-01-01

This hypothesis-driven laboratory exercise teaches how DNA evidence can be used to investigate an organism's evolutionary history while providing practical modeling of the fundamental processes of gene transcription and translation. We used an inquiry-based approach to construct a laboratory around a nontrivial, open-ended evolutionary question…

Forty Years Later: Updating the Fossilization Hypothesis

ERIC Educational Resources Information Center

Han, ZhaoHong

2013-01-01

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

An integration of integrated information theory with fundamental physics

PubMed Central

Barrett, Adam B.

2014-01-01

To truly eliminate Cartesian ghosts from the science of consciousness, we must describe consciousness as an aspect of the physical. Integrated Information Theory states that consciousness arises from intrinsic information generated by dynamical systems; however existing formulations of this theory are not applicable to standard models of fundamental physical entities. Modern physics has shown that fields are fundamental entities, and in particular that the electromagnetic field is fundamental. Here I hypothesize that consciousness arises from information intrinsic to fundamental fields. This hypothesis unites fundamental physics with what we know empirically about the neuroscience underlying consciousness, and it bypasses the need to consider quantum effects. PMID:24550877

Stereotypic Laryngeal and Respiratory Motor Patterns Generate Different Call Types in Rat Ultrasound Vocalization

PubMed Central

RIEDE, TOBIAS

2014-01-01

Rodents produce highly variable ultrasound whistles as communication signals unlike many other mammals, who employ flow-induced vocal fold oscillations to produce sound. The role of larynx muscles in controlling sound features across different call types in ultrasound vocalization (USV) was investigated using laryngeal muscle electromyographic (EMG) activity, subglottal pressure measurements and vocal sound output in awake and spontaneously behaving Sprague–Dawley rats. Results support the hypothesis that glottal shape determines fundamental frequency. EMG activities of thyroarytenoid and cricothyroid muscles were aligned with call duration. EMG intensity increased with fundamental frequency. Phasic activities of both muscles were aligned with fast changing fundamental frequency contours, for example in trills. Activities of the sternothyroid and sternohyoid muscles, two muscles involved in vocal production in other mammals, are not critical for the production of rat USV. To test how stereotypic laryngeal and respiratory activity are across call types and individuals, sets of ten EMG and subglottal pressure parameters were measured in six different call types from six rats. Using discriminant function analysis, on average 80% of parameter sets were correctly assigned to their respective call type. This was significantly higher than the chance level. Since fundamental frequency features of USV are tightly associated with stereotypic activity of intrinsic laryngeal muscles and muscles contributing to build-up of subglottal pressure, USV provide insight into the neurophysiological control of peripheral vocal motor patterns. PMID:23423862

Breast tumor heterogeneity: cancer stem cells or clonal evolution?

PubMed

Campbell, Lauren L; Polyak, Kornelia

2007-10-01

Breast tumors are composed of a variety of cell types with distinct morphologies and behaviors. It is not clear how this tumor heterogeneity comes about. Two popular concepts that attempt to explain this are the cancer stem cell hypothesis and the clonal evolution model. Each of these ideas has been investigated for some time, leading to the accumulation of numerous findings that are used to support one or the other. Although the two views share some similarities, they are fundamentally different notions with very different clinical implications. Analysis of the research backing each concept, along with a review of the results of our recent study investigating putative breast cancer stem cells, suggests how the cancer stem cell hypothesis and the clonal evolution model may be involved in generating breast tumor heterogeneity. An understanding of this process will allow the development of more effective ways to treat and prevent breast cancer.

Auditory Temporal Processing as a Specific Deficit among Dyslexic Readers

ERIC Educational Resources Information Center

Fostick, Leah; Bar-El, Sharona; Ram-Tsur, Ronit

2012-01-01

The present study focuses on examining the hypothesis that auditory temporal perception deficit is a basic cause for reading disabilities among dyslexics. This hypothesis maintains that reading impairment is caused by a fundamental perceptual deficit in processing rapid auditory or visual stimuli. Since the auditory perception involves a number of…

Philosophical Foundations of Zwicky's Morphological Approach in Science

NASA Astrophysics Data System (ADS)

Rudnicki, Konrad

Fritz Zwicky as a conscious Goetheanist. Johann Wolfgang Goethe as a natural philosopher and methodologist. Goetheanist theory of knowledge — a theory essentially different from the theory of Kant, from which the contemporary concept of paradigms has originated. Pre-scientific character of theory of knowledge. The principal thought experiment. The role of thinking in Goetheanism. Fundamental phenomena. Morphological approach. The shape (µo ) of a problem. Morphological box. Individual hypothesis versus classes of hypotheses. Theory and reality.

The Impact of Vocal Hyperfunction on Relative Fundamental Frequency during Voicing Offset and Onset

ERIC Educational Resources Information Center

Stepp, Cara E.; Hillman, Robert E.; Heaton, James T.

2010-01-01

Purpose: This study tested the hypothesis that individuals with vocal hyperfunction would show decreases in relative fundamental frequency (RFF) surrounding a voiceless consonant. Method: This retrospective study of 2 clinical databases used speech samples from 15 control participants and women with hyperfunction-related voice disorders: 82 prior…

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

PubMed

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.

In Defense of Chi's Ontological Incompatibility Hypothesis

ERIC Educational Resources Information Center

Slotta, James D.

2011-01-01

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

Explorations in Statistics: Hypothesis Tests and P Values

ERIC Educational Resources Information Center

Curran-Everett, Douglas

2009-01-01

Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This second installment of "Explorations in Statistics" delves into test statistics and P values, two concepts fundamental to the test of a scientific null hypothesis. The essence of a test statistic is that it compares what…

The dominant mode of standing Alfven waves at synchronous orbit

NASA Technical Reports Server (NTRS)

Cummings, W. D.; Countee, C.; Lyons, D.; Wiley, W., III

1975-01-01

Low-frequency oscillations of the earth's magnetic field recorded by the UCLA magnetometer on board ATS-1, have been examined for the six-month interval, January-June, 1968. The initial interpretation, that these oscillations represent the second harmonic of a standing Alfven wave, has been re-examined, and it is concluded that this hypothesis must be withdrawn. Using evidence from OGO-5 and ATS-5, as well as the data from ATS-1, it is argued that the dominant mode at the synchronous orbit must be the fundamental rather than the second harmonic. From 14 instances when the oscillations of distinctly different periods occurred during the same time interval at ATS-1 it is concluded that higher harmonics can exist. The period ratio in 7 of the 14 cases corresponds to the simultaneous occurrence of the second harmonic with the fundamental, and 4 other cases could be identified as the simultaneous occurrence of the fourth harmonic with the fundamental.

The Origins of Ethnolinguistic Diversity

PubMed Central

Michalopoulos, Stelios

2013-01-01

This study explores the determinants of ethnolinguistic diversity within as well as across countries shedding light on its geographic origins. The empirical analysis conducted across countries, virtual countries and pairs of contiguous regions establishes that geographic variability, captured by variation in regional land quality and elevation, is a fundamental determinant of contemporary linguistic diversity. The findings are consistent with the proposed hypothesis that differences in land endowments gave rise to location-specific human capital, leading to the formation of localized ethnicities. PMID:25258434

Constrained inversion as a hypothesis testing tool, what can we learn about the lithosphere?

NASA Astrophysics Data System (ADS)

Moorkamp, Max; Stewart, Fishwick; Jones, Alan G.

2017-04-01

Inversion of geophysical data constrained by a reference model is typically used to guide the inversion of low resolution data towards a geologically plausible solution. For example, a migrated seismic section can provide the location of lithological boundaries for potential field inversions. Here we consider the inversion of long-period magnetotelluric data constrained by models generated through surface wave inversion. In this case, we do not consider the surface wave model inherently better in any sense and want to guide the magnetotelluric inversion towards this model, but we want to test the hypothesis that both datasets can be explained by models with similar structure. If the hypothesis test is successful, i.e. we can fit the observations with a conductivity model with structural similarity to the seismic model, we have found an alternative explanation compared to the individual inversion and can use the differences to learn about the resolution of the magnetotelluric data and can improve our interpretation. Conversely, if the test refutes our hypothesis of coincident structure, we have found features in the models that are sensed fundamentally different by both methods which is potentially instructive on the nature of the anomalies. We use a MT dataset acquired in central Botswana over the Okwa terrane and the adjacent Kaapvaal and Zimbabwe Cratons together with a tomographic model for the region to illustrate and test this approach. Here, various conductive structures have been identified that bridge the Moho. Furthermore, the thickness of the lithosphere inferred from the different methods differs. In both cases the question is in how far this is a result of the ill-posed nature of inversion and in how far these differences can be reconciled. Thus this dataset is an ideal test case for our hypothesis testing approach. Finally, we will demonstrate how we can use the results of the constrained inversion to extract conductivity-velocity relationships in the region and gain further insight into the composition and thermal structure of the lithosphere.

Perceptual Inference in Chronic Pain: An Investigation Into the Economy of Action Hypothesis.

PubMed

Tabor, Abby; O'Daly, Owen; Gregory, Robert W; Jacobs, Clair; Travers, Warren; Thacker, Michael A; Moseley, Graham Lorimer

2016-07-01

The experience of chronic pain critically alters one's ability to interact with their environment. One fundamental issue that has received little attention, however, is whether chronic pain disrupts how one perceives their environment in the first place. The Economy of Action hypothesis purports that the environment is spatially scaled according to the ability of the observer. Under this hypothesis it has been proposed that the perception of the world is different between those with and without chronic pain. Such a possibility has profound implications for the investigation and treatment of pain. The present investigation tested the application of this hypothesis to a heterogenous chronic pain population. Individuals with chronic pain (36; 27F) and matched pain-free controls were recruited. Each participant was required to judge the distance to a series of target cones, to which they were to subsequently walk. In addition, at each distance, participants used Numerical Rating Scales to indicate their perceived effort and perceived pain associated with the distance presented. Our findings do not support the Economy of Action hypothesis: there were no significant differences in distance estimates between the chronic pain and pain-free groups (F1,60=0.927; P=0.340). In addition, we found no predictive relationship in the chronic pain group between anticipated pain and estimated distance (F1,154=0.122, P=0.727), nor anticipated effort (1.171, P=0.281) and estimated distance (F1,154=1.171, P=0.281). The application of the Economy of Action hypothesis and the notion of spatial perceptual scaling as a means to assess and treat the experience of chronic pain are not supported by the results of this study.

The (not so) immortal strand hypothesis.

PubMed

Tomasetti, Cristian; Bozic, Ivana

2015-03-01

Non-random segregation of DNA strands during stem cell replication has been proposed as a mechanism to minimize accumulated genetic errors in stem cells of rapidly dividing tissues. According to this hypothesis, an "immortal" DNA strand is passed to the stem cell daughter and not the more differentiated cell, keeping the stem cell lineage replication error-free. After it was introduced, experimental evidence both in favor and against the hypothesis has been presented. Using a novel methodology that utilizes cancer sequencing data we are able to estimate the rate of accumulation of mutations in healthy stem cells of the colon, blood and head and neck tissues. We find that in these tissues mutations in stem cells accumulate at rates strikingly similar to those expected without the protection from the immortal strand mechanism. Utilizing an approach that is fundamentally different from previous efforts to confirm or refute the immortal strand hypothesis, we provide evidence against non-random segregation of DNA during stem cell replication. Our results strongly suggest that parental DNA is passed randomly to stem cell daughters and provides new insight into the mechanism of DNA replication in stem cells. Copyright © 2015. Published by Elsevier B.V.

The (not so) Immortal Strand Hypothesis

PubMed Central

Tomasetti, Cristian; Bozic, Ivana

2015-01-01

Background Non-random segregation of DNA strands during stem cell replication has been proposed as a mechanism to minimize accumulated genetic errors in stem cells of rapidly dividing tissues. According to this hypothesis, an “immortal” DNA strand is passed to the stem cell daughter and not the more differentiated cell, keeping the stem cell lineage replication error-free. After it was introduced, experimental evidence both in favor and against the hypothesis has been presented. Principal Findings Using a novel methodology that utilizes cancer sequencing data we are able to estimate the rate of accumulation of mutations in healthy stem cells of the colon, blood and head and neck tissues. We to find that in these tissues mutations in stem cells accumulate at rates strikingly similar to those expected without the protection from the immortal strand mechanism. Significance Utilizing an approach that is fundamentally different from previous efforts to confirm or refute the immortal strand hypothesis, we provide strong evidence against non-random segregation of DNA during stem cell replication. Our results strongly suggest that parental DNA is passed randomly to stem cell daughters and provides new insight into the mechanism of DNA replication in stem cells. PMID:25700960

Dopamine and reward: the anhedonia hypothesis 30 years on.

PubMed

Wise, Roy A

2008-10-01

The anhedonia hypothesis--that brain dopamine plays a critical role in the subjective pleasure associated with positive rewards--was intended to draw the attention of psychiatrists to the growing evidence that dopamine plays a critical role in the objective reinforcement and incentive motivation associated with food and water, brain stimulation reward, and psychomotor stimulant and opiate reward. The hypothesis called to attention the apparent paradox that neuroleptics, drugs used to treat a condition involving anhedonia (schizophrenia), attenuated in laboratory animals the positive reinforcement that we normally associate with pleasure. The hypothesis held only brief interest for psychiatrists, who pointed out that the animal studies reflected acute actions of neuroleptics whereas the treatment of schizophrenia appears to result from neuroadaptations to chronic neuroleptic administration, and that it is the positive symptoms of schizophrenia that neuroleptics alleviate, rather than the negative symptoms that include anhedonia. Perhaps for these reasons, the hypothesis has had minimal impact in the psychiatric literature. Despite its limited heuristic value for the understanding of schizophrenia, however, the anhedonia hypothesis has had major impact on biological theories of reinforcement, motivation, and addiction. Brain dopamine plays a very important role in reinforcement of response habits, conditioned preferences, and synaptic plasticity in cellular models of learning and memory. The notion that dopamine plays a dominant role in reinforcement is fundamental to the psychomotor stimulant theory of addiction, to most neuroadaptation theories of addiction, and to current theories of conditioned reinforcement and reward prediction. Properly understood, it is also fundamental to recent theories of incentive motivation.

Gender similarities and differences.

PubMed

Hyde, Janet Shibley

2014-01-01

Whether men and women are fundamentally different or similar has been debated for more than a century. This review summarizes major theories designed to explain gender differences: evolutionary theories, cognitive social learning theory, sociocultural theory, and expectancy-value theory. The gender similarities hypothesis raises the possibility of theorizing gender similarities. Statistical methods for the analysis of gender differences and similarities are reviewed, including effect sizes, meta-analysis, taxometric analysis, and equivalence testing. Then, relying mainly on evidence from meta-analyses, gender differences are reviewed in cognitive performance (e.g., math performance), personality and social behaviors (e.g., temperament, emotions, aggression, and leadership), and psychological well-being. The evidence on gender differences in variance is summarized. The final sections explore applications of intersectionality and directions for future research.

The bioclimatic envelope of the wolverine (Gulo gulo): do climatic constraints limit its geographic distribution?

Treesearch

J. P. Copeland; K. S. McKelvey; K. B. Aubry; A. Landa; J. Persson; R. M. Inman; J. Krebs; E. Lofroth; H. Golden; J. R. Squires; A. Magoun; M. K. Schwartz; J. Wilmot; C. L. Copeland; R. E. Yates; I. Kojola; R. May

2010-01-01

We propose a fundamental geographic distribution for the wolverine (Gulo gulo (L., 1758)) based on the hypothesis that the occurrence of wolverines is constrained by their obligate association with persistent spring snow cover for successful reproductive denning and by an upper limit of thermoneutrality. To investigate this hypothesis, we developed a composite of MODIS...

Aerobic scope measurements of fishes in an era of climate change: respirometry, relevance and recommendations.

PubMed

Clark, Timothy D; Sandblom, Erik; Jutfelt, Fredrik

2013-08-01

Measurements of aerobic scope [the difference between minimum and maximum oxygen consumption rate ( and , respectively)] are increasing in prevalence as a tool to address questions relating to fish ecology and the effects of climate change. However, there are underlying issues regarding the array of methods used to measure aerobic scope across studies and species. In an attempt to enhance quality control before the diversity of issues becomes too great to remedy, this paper outlines common techniques and pitfalls associated with measurements of , and aerobic scope across species and under different experimental conditions. Additionally, we provide a brief critique of the oxygen- and capacity-limited thermal tolerance (OCLTT) hypothesis, a concept that is intricately dependent on aerobic scope measurements and is spreading wildly throughout the literature despite little evidence for its general applicability. It is the intention of this paper to encourage transparency and accuracy in future studies that measure the aerobic metabolism of fishes, and to highlight the fundamental issues with assuming broad relevance of the OCLTT hypothesis.

Perception of English intonation by English, Spanish, and Chinese listeners.

PubMed

Grabe, Esther; Rosner, Burton S; García-Albea, José E; Zhou, Xiaolin

2003-01-01

Native language affects the perception of segmental phonetic structure, of stress, and of semantic and pragmatic effects of intonation. Similarly, native language might influence the perception of similarities and differences among intonation contours. To test this hypothesis, a cross-language experiment was conducted. An English utterance was resynthesized with seven falling and four rising intonation contours. English, Iberian Spanish, and Chinese listeners then rated each pair of nonidentical stimuli for degree of difference. Multidimensional scaling of the results supported the hypothesis. The three groups of listeners produced statistically different perceptual configurations for the falling contours. All groups, however, perceptually separated the falling from the rising contours. This result suggested that the perception of intonation begins with the activation of universal auditory mechanisms that process the direction of relatively slow frequency modulations. A second experiment therefore employed frequency-modulated sine waves that duplicated the fundamental frequency contours of the speech stimuli. New groups of English, Spanish, and Chinese subjects yielded no cross-language differences between the perceptual configurations for these nonspeech stimuli. The perception of similarities and differences among intonation contours calls upon universal auditory mechanisms whose output is molded by experience with one's native language.

Explorations in statistics: hypothesis tests and P values.

PubMed

Curran-Everett, Douglas

2009-06-01

Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This second installment of Explorations in Statistics delves into test statistics and P values, two concepts fundamental to the test of a scientific null hypothesis. The essence of a test statistic is that it compares what we observe in the experiment to what we expect to see if the null hypothesis is true. The P value associated with the magnitude of that test statistic answers this question: if the null hypothesis is true, what proportion of possible values of the test statistic are at least as extreme as the one I got? Although statisticians continue to stress the limitations of hypothesis tests, there are two realities we must acknowledge: hypothesis tests are ingrained within science, and the simple test of a null hypothesis can be useful. As a result, it behooves us to explore the notions of hypothesis tests, test statistics, and P values.

The evolution of altruistic social preferences in human groups

PubMed Central

Silk, Joan B.; House, Bailey R.

2016-01-01

In this paper, we consider three hypotheses to account for the evolution of the extraordinary capacity for large-scale cooperation and altruistic social preferences within human societies. One hypothesis is that human cooperation is built on the same evolutionary foundations as cooperation in other animal societies, and that fundamental elements of the social preferences that shape our species' cooperative behaviour are also shared with other closely related primates. Another hypothesis is that selective pressures favouring cooperative breeding have shaped the capacity for cooperation and the development of social preferences, and produced a common set of behavioural dispositions and social preferences in cooperatively breeding primates and humans. The third hypothesis is that humans have evolved derived capacities for collaboration, group-level cooperation and altruistic social preferences that are linked to our capacity for culture. We draw on naturalistic data to assess differences in the form, scope and scale of cooperation between humans and other primates, experimental data to evaluate the nature of social preferences across primate species, and comparative analyses to evaluate the evolutionary origins of cooperative breeding and related forms of behaviour. PMID:26729936

Inoculation Stress Hypothesis of Environmental Enrichment

PubMed Central

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

2014-01-01

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

Inoculation stress hypothesis of environmental enrichment.

PubMed

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

2015-02-01

One hallmark of psychiatric conditions is the vast continuum of individual differences in susceptibility vs. resilience resulting from the interaction of genetic and environmental factors. The environmental enrichment paradigm is an animal model that is useful for studying a range of psychiatric conditions, including protective phenotypes in addiction and depression models. The major question is how environmental enrichment, a non-drug and non-surgical manipulation, can produce such robust individual differences in such a wide range of behaviors. This paper draws from a variety of published sources to outline a coherent hypothesis of inoculation stress as a factor producing the protective enrichment phenotypes. The basic tenet suggests that chronic mild stress from living in a complex environment and interacting non-aggressively with conspecifics can inoculate enriched rats against subsequent stressors and/or drugs of abuse. This paper reviews the enrichment phenotypes, mulls the fundamental nature of environmental enrichment vs. isolation, discusses the most appropriate control for environmental enrichment, and challenges the idea that cortisol/corticosterone equals stress. The intent of the inoculation stress hypothesis of environmental enrichment is to provide a scaffold with which to build testable hypotheses for the elucidation of the molecular mechanisms underlying these protective phenotypes and thus provide new therapeutic targets to treat psychiatric/neurological conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Multiple optimality criteria support Ornithoscelida

NASA Astrophysics Data System (ADS)

Parry, Luke A.; Baron, Matthew G.; Vinther, Jakob

2017-10-01

A recent study of early dinosaur evolution using equal-weights parsimony recovered a scheme of dinosaur interrelationships and classification that differed from historical consensus in a single, but significant, respect; Ornithischia and Saurischia were not recovered as monophyletic sister-taxa, but rather Ornithischia and Theropoda formed a novel clade named Ornithoscelida. However, these analyses only used maximum parsimony, and numerous recent simulation studies have questioned the accuracy of parsimony under equal weights. Here, we provide additional support for this alternative hypothesis using Bayesian implementation of the Mkv model, as well as through number of additional parsimony analyses, including implied weighting. Using Bayesian inference and implied weighting, we recover the same fundamental topology for Dinosauria as the original study, with a monophyletic Ornithoscelida, demonstrating that the main suite of methods used in morphological phylogenetics recover this novel hypothesis. This result was further scrutinized through the systematic exclusion of different character sets. Novel characters from the original study (those not taken or adapted from previous phylogenetic studies) were found to be more important for resolving the relationships within Dinosauromorpha than the relationships within Dinosauria. Reanalysis of a modified version of the character matrix that supports the Ornithischia-Saurischia dichotomy under maximum parsimony also supports this hypothesis under implied weighting, but not under the Mkv model, with both Theropoda and Sauropodomorpha becoming paraphyletic with respect to Ornithischia.

Is the Limit-Cycle-Attractor an (almost) invariable characteristic in human walking?

PubMed

Broscheid, Kim-Charline; Dettmers, Christian; Vieten, Manfred

2018-05-16

Common methods of gait analyses measure step length/width, gait velocity and gait variability to name just a few. Those parameters tend to be changing with fitness and skill of the subjects. But, do stable subject characteristic parameters in walking exist? Does the Limit-Cycle-Attractor qualify as such a parameter?. The attractor method is a new approach focusing on the dynamics of human motion. It classifies the fundamental walking pattern by calculating the Limit-Cycle-Attractor and its variability from acceleration data of the feet. Our hypothesis is that the fundamental walking pattern in healthy controls and in people with Multiple Sclerosis (pwMS) is stable, but can be altered through acute interventions or rehabilitation. For this purpose, two investigations were conducted involving 113 subjects. The short-term stability was tested pre and post a 15 min passive/active MOTOmed (ergometer) session as well as up to 20 min afterwards. The long-term stability was tested over five weeks of rehabilitation once a week in pwMS. The main parameter of interest describes the velocity normalized average difference between two attractors (δM), which is an indicator for the change in movement pattern. The Friedman's two-way ANOVA by ranks did not reveal any significant difference in δM. However, the conventional walking tests (6 min.10 m) improved significantly (p < 0.05) during rehabilitation. Contrary to our original hypothesis, the fundamental walking pattern was highly stable against controlled motor-assisted movement initiation via MOTOmed and rehabilitation treatment. Movement characteristics appeared to be independent of the improved fitness as indicated by the enhanced walking speed and distance. The individual Limit-Cycle-Attractor is extremely robust and might indeed qualify as an (almost) invariable characteristic in human walking. This opens up the possibility to encode the individual walking characteristics. Conditions as Parkinson, Multiple Sclerosis etc., might display disease specific distinctions via the Limit-Cycle-Attractor. Copyright © 2018 Elsevier B.V. All rights reserved.

The X-ray structure of a galaxy cluster at z = 0.54 - Implications for cluster evolution and cosmology

NASA Technical Reports Server (NTRS)

White, S. D. M.; Silk, J.; Henry, J. P.

1981-01-01

High-resolution X-ray observations of the rich cluster 0016+16 at a redshift of 0.541 are presented. The emitting gas in this cluster is hot and extremely luminous, and its structure resembles that seen in the brightest nearby cluster sources. In most of its properties, 0016+16 resembles a richer version of the Coma cluster, and it offers little support to the hypothesis that clusters at z greater than 0.5 differ fundamentally from nearer objects.

The equilibrium-point hypothesis--past, present and future.

PubMed

Feldman, Anatol G; Levin, Mindy F

2009-01-01

This chapter is a brief account of fundamentals of the equilibrium-point hypothesis or more adequately called the threshold control theory (TCT). It also compares the TCT with other approaches to motor control. The basic notions of the TCT are reviewed with a major focus on solutions to the problems of multi-muscle and multi-degrees of freedom redundancy. The TCT incorporates cognitive aspects by explaining how neurons recognize that internal (neural) and external (environmental) events match each other. These aspects as well as how motor learning occurs are subjects of further development of the TCT hypothesis.

Cognition and the evolution of music: pitfalls and prospects.

PubMed

Honing, Henkjan; Ploeger, Annemie

2012-10-01

What was the role of music in the evolutionary history of human beings? We address this question from the point of view that musicality can be defined as a cognitive trait. Although it has been argued that we will never know how cognitive traits evolved (Lewontin, 1998), we argue that we may know the evolution of music by investigating the fundamental cognitive mechanisms of musicality, for example, relative pitch, tonal encoding of pitch, and beat induction. In addition, we show that a nomological network of evidence (Schmitt & Pilcher, 2004) can be built around the hypothesis that musicality is a cognitive adaptation. Within this network, different modes of evidence are gathered to support a specific evolutionary hypothesis. We show that the combination of psychological, medical, physiological, genetic, phylogenetic, hunter-gatherer, and cross-cultural evidence indicates that musicality is a cognitive adaptation. Copyright © 2012 Cognitive Science Society, Inc.

Prediction of biodiversity hotspots in the Anthropocene: The case of veteran oaks.

PubMed

Skarpaas, Olav; Blumentrath, Stefan; Evju, Marianne; Sverdrup-Thygeson, Anne

2017-10-01

Over the past centuries, humans have transformed large parts of the biosphere, and there is a growing need to understand and predict the distribution of biodiversity hotspots influenced by the presence of humans. Our basic hypothesis is that human influence in the Anthropocene is ubiquitous, and we predict that biodiversity hot spot modeling can be improved by addressing three challenges raised by the increasing ecological influence of humans: (i) anthropogenically modified responses to individual ecological factors, (ii) fundamentally different processes and predictors in landscape types shaped by different land use histories and (iii) a multitude and complexity of natural and anthropogenic processes that may require many predictors and even multiple models in different landscape types. We modeled the occurrence of veteran oaks in Norway, and found, in accordance with our basic hypothesis and predictions, that humans influence the distribution of veteran oaks throughout its range, but in different ways in forests and open landscapes. In forests, geographical and topographic variables related to the oak niche are still important, but the occurrence of veteran oaks is shifted toward steeper slopes, where logging is difficult. In open landscapes, land cover variables are more important, and veteran oaks are more common toward the north than expected from the fundamental oak niche. In both landscape types, multiple predictor variables representing ecological and human-influenced processes were needed to build a good model, and several models performed almost equally well. Models accounting for the different anthropogenic influences on landscape structure and processes consistently performed better than models based exclusively on natural biogeographical and ecological predictors. Thus, our results for veteran oaks clearly illustrate the challenges to distribution modeling raised by the ubiquitous influence of humans, even in a moderately populated region, but also show that predictions can be improved by explicitly addressing these anthropogenic complexities.

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

NASA Astrophysics Data System (ADS)

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.

A mechanism producing power law etc. distributions

NASA Astrophysics Data System (ADS)

Li, Heling; Shen, Hongjun; Yang, Bin

2017-07-01

Power law distribution is playing an increasingly important role in the complex system study. Based on the insolvability of complex systems, the idea of incomplete statistics is utilized and expanded, three different exponential factors are introduced in equations about the normalization condition, statistical average and Shannon entropy, with probability distribution function deduced about exponential function, power function and the product form between power function and exponential function derived from Shannon entropy and maximal entropy principle. So it is shown that maximum entropy principle can totally replace equal probability hypothesis. Owing to the fact that power and probability distribution in the product form between power function and exponential function, which cannot be derived via equal probability hypothesis, can be derived by the aid of maximal entropy principle, it also can be concluded that maximal entropy principle is a basic principle which embodies concepts more extensively and reveals basic principles on motion laws of objects more fundamentally. At the same time, this principle also reveals the intrinsic link between Nature and different objects in human society and principles complied by all.

A Hypothesis on Biological Protection from Space Radiation Through the Use of Therapeutic Gases

NASA Technical Reports Server (NTRS)

Schoenfeld, Michael

2011-01-01

This slide presentation proposes a hypothesis to use therapeutic gases in space to enhance the biological protection for astronauts from space radiation. The fundamental role in how radiation causes biological damage appears to be radiolysis, the dissociation of water by radiation. A chain of events appears to cause molecular and biological transformations that ultimately manifest into medical diseases. The hypothesis of this work is that applying medical gases may increase resistance to radiation, by possessing the chemical properties that effectively improve the radical scavenging and enhance bond repair and to induce biological processes which enhance and support natural resistance and repair mechanisms.

Fundamentals of clinical methodology: 2. Etiology.

PubMed

Sadegh-Zadeh, K

1998-03-01

The concept of etiology is analyzed and the possibilities and limitations of deterministic, probabilistic, and fuzzy etiology are explored. Different kinds of formal structures for the relation of causation are introduced which enable us to explicate the notion of cause on qualitative, comparative, and quantitative levels. The conceptual framework developed is an approach to a theory of causality that may be useful in etiologic research, in building nosological systems, and in differential diagnosis, therapeutic decision-making, and controlled clinical trials. The bearings of the theory are exemplified by examining the current Chlamydia pneumoniae hypothesis on the incidence of myocardial infarction.

Spatio-temporal conditional inference and hypothesis tests for neural ensemble spiking precision

PubMed Central

Harrison, Matthew T.; Amarasingham, Asohan; Truccolo, Wilson

2014-01-01

The collective dynamics of neural ensembles create complex spike patterns with many spatial and temporal scales. Understanding the statistical structure of these patterns can help resolve fundamental questions about neural computation and neural dynamics. Spatio-temporal conditional inference (STCI) is introduced here as a semiparametric statistical framework for investigating the nature of precise spiking patterns from collections of neurons that is robust to arbitrarily complex and nonstationary coarse spiking dynamics. The main idea is to focus statistical modeling and inference, not on the full distribution of the data, but rather on families of conditional distributions of precise spiking given different types of coarse spiking. The framework is then used to develop families of hypothesis tests for probing the spatio-temporal precision of spiking patterns. Relationships among different conditional distributions are used to improve multiple hypothesis testing adjustments and to design novel Monte Carlo spike resampling algorithms. Of special note are algorithms that can locally jitter spike times while still preserving the instantaneous peri-stimulus time histogram (PSTH) or the instantaneous total spike count from a group of recorded neurons. The framework can also be used to test whether first-order maximum entropy models with possibly random and time-varying parameters can account for observed patterns of spiking. STCI provides a detailed example of the generic principle of conditional inference, which may be applicable in other areas of neurostatistical analysis. PMID:25380339

The race to the nociceptor: mechanical versus temperature effects in thermal pain of dental neurons

NASA Astrophysics Data System (ADS)

Lin, Min; Liu, Fusheng; Liu, Shaobao; Ji, Changchun; Li, Ang; Lu, Tian Jian; Xu, Feng

2017-04-01

The sensing of hot and cold stimuli by dental neurons differs in several fundamental ways. These sensations have been characterized quantitatively through the measured time course of neural discharge signals that result from hot or cold stimuli applied to the teeth of animal models. Although various hypotheses have been proposed to explain the underlying mechanism, the ability to test competing hypotheses against experimental recorded data using biophysical models has been hindered by limitations in our understanding of the specific ion channels involved in nociception of dental neurons. Here we apply recent advances in established biophysical models to test the competing hypotheses. We show that a sharp shooting pain sensation experienced shortly following cold stimulation cannot be attributed to the activation of thermosensitive ion channels, thereby falsifying the so-called neuronal hypothesis, which states that rapidly transduced sensations of coldness are related to thermosensitive ion channels. Our results support a central role of mechanosensitive ion channels and the associated hydrodynamic hypothesis. In addition to the hydrodynamic hypothesis, we also demonstrate that the long time delay of dental neuron responses after hot stimulation could be attributed to the neuronal hypothesis—that a relatively long time is required for the temperature around nociceptors to reach some threshold. The results are useful as a model of how multiphysical phenomena can be combined to provide mechanistic insight into different mechanisms underlying pain sensations.

Creation, Phase Change and Evolution of the Universe Based on the "Convection Bang Hypothesis"

NASA Astrophysics Data System (ADS)

Gholibeigian, Hassan; Amirshahkarami, Abdolazim; Gholibeigian, Kazem

2016-04-01

In our vision, it is believed that creation and phase change of universe and their coupling began by the gigantic Large Scale Forced Convection System (LSFCS) in very high temperature including a swirling wild wind and energetic particles like gravitons. That wind as the creator of the inflation process was carrying many Quantum Convection Loops (QCLs). Those QCLs have been transformed to black holes as the cores of galaxies. Convection Bang (CB) Model for creation, phase change and evolution of the Universe is constituted based on three assumptions as follows: The first is: "Gravity Hypothesis" that describes the gravity fields generation by the LSFCSs of the heat and mass inside the planets, stars, galaxies and clusters. The LSFCS changes the material properties of the domain and produces coupling of the matched electromagnetic and gravity fields. Gravity hypothesis is a new way to understand gravitation phenomenon which is different from the both Newton's law of gravity and Einstein's theory of general relativity approaches [Gholibeigian et. al, AGU Fall Meeting 2015, P11A-2056 ]. The second is: "Substantial Motion" theory of Iranian philosopher, Mulla Sadra (1571/2-1640), which describes space-time, time's relativity for all atoms (bodies) which are different from each other [Gholibeigian, APS April Meeting 2015, abstract #L1.027], atom's (body) volume squeezing, black hole's mass lightening while increases the velocities of its involved masses inward (a paradox with general relativity), and changes of material properties and geometries in speed of near light speed [Gholibeigian, APS March Meeting 2016, abstract #]. The third is: "Animated Sub-particles" model. These sub-particles (sub-strings) are origin of life and creator of the momentums of the fundamental particles and forces, and basic link of the information transfer to them, [Gholibeigian, APS April Meeting 2015, abstract #L1.027]. In this model, there are four proposed animated sub-particles of mater, plant, animal and human in substructure of each fundamental particle (string) as the origins of life and cause of differences between their spins. Material's sub-particle is always on and active (from beginning of CB). When the environmental conditions became ready for creation of each field of the plants, animals and humans, sub-particles of their elementary particles became on and active and then, those elementary particles participated in processes of creation (phase change) in their own fields. Sub-particles lead the fundamental particles in both individually and systematic (nucleons, atoms, molecules, gens, us...) forms. Sub-particles' system is inside of particles' (bodies)' system. Mechanism: Universe has been managed by coupling of these three assumptions in two micro and macro coupling scales. God, as the main source of information, has been communicated with sub-particles and transfers a package (bit) of information and laws (plus standard ethics for human's sub-particles) to each of them from their inside and outside for process and selection (mutation) of the next step of the motion (phase change) and coupling/communication of their fundamental particles with each other in each Plank's time (or smaller scale). This process is causality for particles' motion in quantum scale too [Gholibeigian, APS March Meeting 2015, abstract #V1.023].

Patterns of host specificity among the helminth parasite fauna of freshwater siluriforms: testing the biogeographical core parasite fauna hypothesis.

PubMed

Rosas-Valdez, Rogelio; de León, Gerardo Pérez-Ponce

2011-04-01

Host specificity plays an essential role in shaping the evolutionary history of host-parasite associations. In this study, an index of host specificity recently proposed was used to test, quantitatively, the hypothesis that some groups of parasites are characteristics of some host fish families along their distribution range. A database with all published records on the helminth parasites of freshwater siluriforms of Mexico was used. The host specificity index was used considering its advantage to measure the taxonomic heterogeneity of the host assemblages and its appropriateness for unequal sampling data. The helminth parasite fauna of freshwater siluriforms in Mexico seems to be specific for different host taxonomic categories. However, a relatively high number of species (47% of the total helminth fauna) is specific to their respective host family. This result provides further corroboration for the biogeographic hypothesis of the core helminth fauna proposed previously. The statistical values for host specificity obtained herein seem to be independent of host range. However, the accurate taxonomic identification of the parasites is fundamental for the evaluation of host specificity and the accurate evolutionary interpretation of this phenomenon.

Toward economics as a new complex system

NASA Astrophysics Data System (ADS)

Kaizoji, Taisei

2016-12-01

The 2015 Nobel Prize in Economic Sciences was awarded to Eugene Fama, Lars Peter Hansen and Robert Shiller for their contributions to the empirical analysis of asset prices. Eugene Fama [J. Finance 25(2), 383 (1970)] is an advocate of the efficient market hypothesis. The efficient market hypothesis assumes that asset price is determined by using all available information and only reacts to new information not incorporated into the fundamentals. Thus, the movement of stock prices is unpredictable. Robert Shiller [ Irrational Exuberance (Princeton Univ. Press, 2015)] has been studying the existence of irrational bubbles, which are defined as the long term deviations of asset price from the fundamentals. This drives us to the unsettled question of how the market actually works. In this paper, I look back at the development of economics and consider the direction in which we should move in order to truly understand the workings of an economic society.

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

PubMed

Wilkinson, Mick

2013-01-01

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

Evolution of cultural traits occurs at similar relative rates in different world regions.

PubMed

Currie, Thomas E; Mace, Ruth

2014-11-22

A fundamental issue in understanding human diversity is whether or not there are regular patterns and processes involved in cultural change. Theoretical and mathematical models of cultural evolution have been developed and are increasingly being used and assessed in empirical analyses. Here, we test the hypothesis that the rates of change of features of human socio-cultural organization are governed by general rules. One prediction of this hypothesis is that different cultural traits will tend to evolve at similar relative rates in different world regions, despite the unique historical backgrounds of groups inhabiting these regions. We used phylogenetic comparative methods and systematic cross-cultural data to assess how different socio-cultural traits changed in (i) island southeast Asia and the Pacific, and (ii) sub-Saharan Africa. The relative rates of change in these two regions are significantly correlated. Furthermore, cultural traits that are more directly related to external environmental conditions evolve more slowly than traits related to social structures. This is consistent with the idea that a form of purifying selection is acting with greater strength on these more environmentally linked traits. These results suggest that despite contingent historical events and the role of humans as active agents in the historical process, culture does indeed evolve in ways that can be predicted from general principles.

Evolution of cultural traits occurs at similar relative rates in different world regions

PubMed Central

Currie, Thomas E.; Mace, Ruth

2014-01-01

A fundamental issue in understanding human diversity is whether or not there are regular patterns and processes involved in cultural change. Theoretical and mathematical models of cultural evolution have been developed and are increasingly being used and assessed in empirical analyses. Here, we test the hypothesis that the rates of change of features of human socio-cultural organization are governed by general rules. One prediction of this hypothesis is that different cultural traits will tend to evolve at similar relative rates in different world regions, despite the unique historical backgrounds of groups inhabiting these regions. We used phylogenetic comparative methods and systematic cross-cultural data to assess how different socio-cultural traits changed in (i) island southeast Asia and the Pacific, and (ii) sub-Saharan Africa. The relative rates of change in these two regions are significantly correlated. Furthermore, cultural traits that are more directly related to external environmental conditions evolve more slowly than traits related to social structures. This is consistent with the idea that a form of purifying selection is acting with greater strength on these more environmentally linked traits. These results suggest that despite contingent historical events and the role of humans as active agents in the historical process, culture does indeed evolve in ways that can be predicted from general principles PMID:25297866

The investigation of chemical structure of coal macerals via transmitted-light FT-IR microscopy by X. Sun

USGS Publications Warehouse

Hower, J.C.; Suarez-Ruiz, I.; Mastalerz, Maria; Cook, A.C.

2007-01-01

A recent paper by Sun [X. Sun, Spectrochim. Acta A 62 (1-3) (2005) 557] attempts to characterize a variety of liptinite, termed "barkinite", from Chinese Permian coals. The component identified does not appear to fundamentally differ from previously-described liptinite macerals included in the International Committee for Coal and Organic Petrology's system of maceral nomenclature. Further, chemical comparisons made with macerals from coals of different rank and age are flawed because the author did not account for changes in chemistry with rank or for the chemical changes associated with botanical changes through geologic time. The author has not satisfactorily proved his hypothesis that the component differs morphologically or chemically from known liptinite-group macerals. ?? 2006 Elsevier B.V. All rights reserved.

The Six Fundamental Characteristics of Chaos and Their Clinical Relevance to Psychiatry: a New Hypothesis for the Origin of Psychosis

NASA Astrophysics Data System (ADS)

Schmid, Gary Bruno

Underlying idea: A new hypothesis about how the mental state of psychosis may arise in the brain as a "linear" information processing pathology is briefly introduced. This hypothesis is proposed in the context of a complementary approach to psychiatry founded in the logical paradigm of chaos theory. To best understand the relation between chaos theory and psychiatry, the semantic structure of chaos theory is analyzed with the help of six general, and six specific, fundamental characteristics which can be directly inferred from empirical observations on chaotic systems. This enables a mathematically and physically stringent perspective on psychological phenomena which until now could only be grasped intuitively: Chaotic systems are in a general sense dynamic, intrinsically coherent, deterministic, recursive, reactive and structured: in a specific sense, self-organizing, unpredictable, nonreproducible, triadic, unstable and self-similar. To a great extent, certain concepts of chaos theory can be associated with corresponding concepts in psychiatry, psychology and psychotherapy, thus enabling an understanding of the human psyche in general as a (fractal) chaotic system and an explanation of certain mental developments, such as the course of schizophrenia, the course of psychosis and psychotherapy as chaotic processes. General overview: A short comparison and contrast of classical and chaotic physical theory leads to four postulates and one hypothesis motivating a new, dynamic, nonlinear approach to classical, causal psychiatry: Process-Oriented PSYchiatry or "POPSY", for short. Four aspects of the relationship between chaos theory and POPSY are discussed: (1) The first of these, namely, Identification of Chaos / Picture of Illness involves a definition of Chaos / Psychosis and a discussion of the 6 logical characteristics of each. This leads to the concept of dynamical disease (definition, characteristics and examples) and to the idea of "psychological disturbance as dynamical illness". On the one hand, it is argued that the developmental course of psychosis is chaotic. On the other hand, we propose the hypothesis that the mental state of psychosis may be a linear information processing pathology. (2) The second aspect under discussion is the Assessment of Chaos / Diagnosis of Illness. In order to better understand how POPSY research treats this aspect, we take a look at the 3 different classes of (non-quantum) motion as models of 3 different possible courses of illness and outline present-day methods available for the quantitative assessment of chaotic (fractal) motion. (3) The third aspect, namely. Prediction of Chaos / Prognosis of Illness considers how each of these 3 classes of motion implies a different way of looking into the future: linear-causal, statistical and nonlinear-fractal, respectively (4) The fourth aspect of the relationship between chaos theory and POPSY, Control of Chaos / Treatment of Illness, is shown to have certain implications to complementary medicine. This paper completes with a short summary, conclusion and a closing remark.

Developmental programming of energy balance regulation: is physical activity more 'programmable' than food intake?

PubMed

Zhu, Shaoyu; Eclarinal, Jesse; Baker, Maria S; Li, Ge; Waterland, Robert A

2016-02-01

Extensive human and animal model data show that environmental influences during critical periods of prenatal and early postnatal development can cause persistent alterations in energy balance regulation. Although a potentially important factor in the worldwide obesity epidemic, the fundamental mechanisms underlying such developmental programming of energy balance are poorly understood, limiting our ability to intervene. Most studies of developmental programming of energy balance have focused on persistent alterations in the regulation of energy intake; energy expenditure has been relatively underemphasised. In particular, very few studies have evaluated developmental programming of physical activity. The aim of this review is to summarise recent evidence that early environment may have a profound impact on establishment of individual propensity for physical activity. Recently, we characterised two different mouse models of developmental programming of obesity; one models fetal growth restriction followed by catch-up growth, and the other models early postnatal overnutrition. In both studies, we observed alterations in body-weight regulation that persisted to adulthood, but no group differences in food intake. Rather, in both cases, programming of energy balance appeared to be due to persistent alterations in energy expenditure and spontaneous physical activity (SPA). These effects were stronger in female offspring. We are currently exploring the hypothesis that developmental programming of SPA occurs via induced sex-specific alterations in epigenetic regulation in the hypothalamus and other regions of the central nervous system. We will summarise the current progress towards testing this hypothesis. Early environmental influences on establishment of physical activity are likely an important factor in developmental programming of energy balance. Understanding the fundamental underlying mechanisms in appropriate animal models will help determine whether early life interventions may be a practical approach to promote physical activity in man.

Theoretical results which strengthen the hypothesis of electroweak bioenantioselection

NASA Astrophysics Data System (ADS)

Zanasi, R.; Lazzeretti, P.; Ligabue, A.; Soncini, A.

1999-03-01

It is shown via a large series of numerical tests on two fundamental organic molecules, the L-α-amino acid L-valine and the sugar precursor hydrated D-glyceraldheyde, that the ab initio calculation of the parity-violating energy shift, at the random-phase approximation level of accuracy, provides results that are about one order of magnitude larger than those obtained by means of less accurate methods employed previously. These findings would make more plausible the hypothesis of electroweak selection of natural enantiomers via the Kondepudi-Nelson scenario, or could imply that Salam phase-transition temperature is higher than previously inferred: accordingly, the hypothesis of terrestrial origin of life would become more realistic.

Laughter differs in children with autism: an acoustic analysis of laughs produced by children with and without the disorder.

PubMed

Hudenko, William J; Stone, Wendy; Bachorowski, Jo-Anne

2009-10-01

Few studies have examined vocal expressions of emotion in children with autism. We tested the hypothesis that during social interactions, children diagnosed with autism would exhibit less extreme laugh acoustics than their nonautistic peers. Laughter was recorded during a series of playful interactions with an examiner. Results showed that children with autism exhibited only one type of laughter, whereas comparison participants exhibited two types. No group differences were found for laugh duration, mean fundamental frequency (F(0)) values, change in F(0), or number of laughs per bout. Findings are interpreted to suggest that children with autism express laughter primarily in response to positive internal states, rather than using laughter to negotiate social interactions.

Temporal Dynamics of Hypothesis Generation: The Influences of Data Serial Order, Data Consistency, and Elicitation Timing

PubMed Central

Lange, Nicholas D.; Thomas, Rick P.; Davelaar, Eddy J.

2012-01-01

The pre-decisional process of hypothesis generation is a ubiquitous cognitive faculty that we continually employ in an effort to understand our environment and thereby support appropriate judgments and decisions. Although we are beginning to understand the fundamental processes underlying hypothesis generation, little is known about how various temporal dynamics, inherent in real world generation tasks, influence the retrieval of hypotheses from long-term memory. This paper presents two experiments investigating three data acquisition dynamics in a simulated medical diagnosis task. The results indicate that the mere serial order of data, data consistency (with previously generated hypotheses), and mode of responding influence the hypothesis generation process. An extension of the HyGene computational model endowed with dynamic data acquisition processes is forwarded and explored to provide an account of the present data. PMID:22754547

Bias in the Counseling Process: How to Recognize and Avoid It.

ERIC Educational Resources Information Center

Morrow, Kelly A.; Deidan, Cecilia T.

1992-01-01

Notes that counselors' vulnerability to inferential bias during counseling process may result in misdiagnosis and improper interventions. Discusses these inferential biases: availability and representativeness heuristics; fundamental attribution error; anchoring, prior knowledge, and labeling; confirmatory hypothesis testing; and reconstructive…

Advantage I-75 mainline automated clearance system : final evaluation report

DOT National Transportation Integrated Search

1998-08-01

The focus of this evaluation was to determine if the Advantage I-75 Mainline Automated Clearance Systems (MACS) produced significant fuel savings for motor carriers. The fundamental hypothesis tested was that the reduction or elimination of stops at ...

Sexual selection on male vocal fundamental frequency in humans and other anthropoids.

PubMed

Puts, David A; Hill, Alexander K; Bailey, Drew H; Walker, Robert S; Rendall, Drew; Wheatley, John R; Welling, Lisa L M; Dawood, Khytam; Cárdenas, Rodrigo; Burriss, Robert P; Jablonski, Nina G; Shriver, Mark D; Weiss, Daniel; Lameira, Adriano R; Apicella, Coren L; Owren, Michael J; Barelli, Claudia; Glenn, Mary E; Ramos-Fernandez, Gabriel

2016-04-27

In many primates, including humans, the vocalizations of males and females differ dramatically, with male vocalizations and vocal anatomy often seeming to exaggerate apparent body size. These traits may be favoured by sexual selection because low-frequency male vocalizations intimidate rivals and/or attract females, but this hypothesis has not been systematically tested across primates, nor is it clear why competitors and potential mates should attend to vocalization frequencies. Here we show across anthropoids that sexual dimorphism in fundamental frequency (F0) increased during evolutionary transitions towards polygyny, and decreased during transitions towards monogamy. Surprisingly, humans exhibit greater F0 sexual dimorphism than any other ape. We also show that low-F0 vocalizations predict perceptions of men's dominance and attractiveness, and predict hormone profiles (low cortisol and high testosterone) related to immune function. These results suggest that low male F0 signals condition to competitors and mates, and evolved in male anthropoids in response to the intensity of mating competition. © 2016 The Author(s).

Gravitropism: interaction of sensitivity modulation and effector redistribution

NASA Technical Reports Server (NTRS)

Evans, M. L.

1991-01-01

Our increasing capabilities for quantitative hormone analysis and automated high resolution growth studies have allowed a reassessment of the classical Cholodny-Went hypothesis of gravitropism. According to this hypothesis, gravity induces redistribution of auxin toward the lower side of the organ and this causes the growth asymmetry that leads to reorientation. Arguments against the Cholodny-Went hypothesis that were based primarily on concerns over the timing and magnitude of the development of hormone asymmetry are countered by recent evidence that such asymmetry develops early and is sufficiently large to account for curvature. Thus, it appears that the Cholodny-Went hypothesis is fundamentally valid. However, recent comparative studies of the kinetics of curvature and the timing of the development of hormone asymmetry indicate that this hypothesis alone cannot account for the intricacies of the gravitropic response. It appears that time-dependent gravity-induced changes in hormone sensitivity as well as changes in sensitivity of the gravity receptor play important roles in the response.

Gravitropism: Interaction of Sensitivity Modulation and Effector Redistribution 1

PubMed Central

Evans, Michael L.

1991-01-01

Our increasing capabilities for quantitative hormone analysis and automated high resolution growth studies have allowed a reassessment of the classical Cholodny-Went hypothesis of gravitropism. According to this hypothesis, gravity induces redistribution of auxin toward the lower side of the organ and this causes the growth asymmetry that leads to reorientation. Arguments against the Cholodny-Went hypothesis that were based primarily on concerns over the timing and magnitude of the development of hormone asymmetry are countered by recent evidence that such asymmetry develops early and is sufficiently large to account for curvature. Thus, it appears that the Cholodny-Went hypothesis is fundamentally valid. However, recent comparative studies of the kinetics of curvature and the timing of the development of hormone asymmetry indicate that this hypothesis alone cannot account for the intricacies of the gravitropic response. It appears that time-dependent gravity-induced changes in hormone sensitivity as well as changes in sensitivity of the gravity receptor play important roles in the response. PMID:11537485

The apparency hypothesis applied to a local pharmacopoeia in the Brazilian northeast

PubMed Central

2014-01-01

Background Data from an ethnobotanical study were analyzed to see if they were in agreement with the biochemical basis of the apparency hypothesis based on an analysis of a pharmacopeia in a rural community adjacent to the Araripe National Forest (Floresta Nacional do Araripe - FLONA) in northeastern Brazil. The apparency hypothesis considers two groups of plants, apparent and non-apparent, that are characterized by conspicuity for herbivores (humans) and their chemical defenses. Methods This study involved 153 interviewees and used semi-structured interviews. The plants were grouped by habit and lignification to evaluate the behavior of these categories in terms of ethnospecies richness, use value and practical and commercial importance. Information about sites for collecting medicinal plants was also obtained. The salience of the ethnospecies was calculated. G-tests were used to test for differences in ethnospecies richness among collection sites and the Kruskal-Wallis test to identify differences in the use values of plants depending on habit and lignifications (e.g. plants were classes as woody or non-woody, the first group comprising trees, shrubs, and lignified climbers (vines) and the latter group comprising herbs and non-lignified climbers). Spearman’s correlation test was performed to relate salience to use value and these two factors with the commercial value of the plants. Results A total of 222 medicinal plants were cited. Herbaceous and woody plants exhibited the highest ethnospecies richness, the non-woody and herbaceous plants had the most practical value (current use), and anthropogenic areas were the main sources of woody and non-woody medicinal plants; herbs and trees were equally versatile in treating diseases and did not differ with regard to use value. Trees were highlighted as the most commercially important growth habit. Conclusions From the perspective of its biochemical fundamentals, the apparency hypothesis does not have predictive potential to explain the use value and commercial value of medicinal plants. In other hand, the herbaceous habit showed the highest ethnospecies richness in the community pharmacopeia, which is an expected prediction, corroborating the apparency hypothesis. PMID:24410756

The death instinct and the mental dimension beyond the pleasure principle in the works of Spielrein and Freud.

PubMed

Caropreso, Fátima

2017-12-01

In 'Destruction as Cause of Come-into-being', Spielrein argues for the need of postulating the existence of a death instinct in mental functioning. The idea that she thus anticipated the concept of death instinct Freud introduced in 1920 is often found in psychoanalytic literature. But the specific meaning of Spielrein's hypothesis is seldom discussed, as well as the extent to which she anticipated Freud's concept. In fact, there are important differences between their views. Besides, a closer analysis of Spielrein's text reveals other ideas that come close to fundamental aspects of Freud's theories from 1920 onwards, particularly the assumption of a more primordial mental functioning than the one regulated by the pleasure principle. But also here there are important differences between the views sustained by both authors. With this in view, the objective of this paper is firstly to discuss some hypotheses formulated by Spielrein in her 1912 work in order to elucidate her concept of death instinct as well as her hypothesis of the existence of a more primitive mental functioning than the one governed by the pleasure principle. Next, the question of the possible similarities and differences with regard to Freud's concepts is also addressed. Copyright © 2017 Institute of Psychoanalysis.

Sex-differences and temporal consistency in stickleback fish boldness.

PubMed

King, Andrew J; Fürtbauer, Ines; Mamuneas, Diamanto; James, Charlotte; Manica, Andrea

2013-01-01

Behavioural traits that co-vary across contexts or situations often reflect fundamental trade-offs which individuals experience in different contexts (e.g. fitness trade-offs between exploration and predation risk). Since males tend to experience greater variance in reproductive success than females, there may be considerable fitness benefits associated with "bolder" behavioural types, but only recently have researchers begun to consider sex-specific and life-history strategies associated with these. Here we test the hypothesis that male three-spined sticklebacks (Gasterosteus aculeatus) show high risk but potentially high return behaviours compared to females. According to this hypothesis we predicted that male fish would show greater exploration of their environment in a foraging context, and be caught sooner by an experimenter than females. We found that the time fish spent out of cover exploring their environment was correlated over two days, and males spent significantly more time out of cover than females. Also, the order in which fish were net-caught from their holding aquarium by an experimenter prior to experiments was negatively correlated with the time spent out of cover during tests, and males tended to be caught sooner than females. Moreover, we found a positive correlation between the catch number prior to our experiments and nine months after, pointing towards consistent, long-term individual differences in behaviour.

Difference in the crab fauna of mangrove areas at a southwest Florida and a northeast Australia location: Implications for leaf litter processing

USGS Publications Warehouse

McIvor, C.C.; Smith, T. J.

1995-01-01

Existing paradigms suggest that mangrove leaf litter is processed primarily via the detrital pathway in forests in the Caribbean biogeographic realm whereas herbivorous crabs are relatively more important litter processors in the Indo-West Pacific. To test this hypothesis, we used pitfall traps to collect intertidal crabs to characterize the crab fauna in a mangrove estuary in southwest Florida. We also tethered mangrove leaves to determine if herbivorous crabs are major leaf consumers there. We compared the results with previously published data collected in an analogous manner from forests in northeastern Australia. The crab fauna in Rookery Bay, Florida, is dominated by carnivorous xanthid and deposit-feeding ocypodid crabs whereas that of the Murray River in northeastern Australia is dominated by herbivorous grapsid crabs. No leaves tethered at five sites in the forests in Southwest Florida were taken by crabs. This contrasts greatly with reported values of leaf removal by crabs in Australian forests of 28-79% of the leaves reaching the forest floor. These differences in the faunal assemblages and in the fate of marked or tethered leaves provide preliminary support for the hypothesis that leaf litter is in fact processed in fundamentally different ways in the two biogeographic realms.

Genetic Structure in the Seabuckthorn Carpenter Moth (Holcocerus hippophaecolus) in China: The Role of Outbreak Events, Geographical and Host Factors

PubMed Central

Tao, Jing; Chen, Min; Zong, Shi-Xiang; Luo, You-Qing

2012-01-01

Understanding factors responsible for structuring genetic diversity is of fundamental importance in evolutionary biology. The seabuckthorn carpenter moth (Holcocerus hippophaecolus Hua) is a native species throughout the north of China and is considered the main threat to seabuckthorn, Hippophae rhamnoides L. We assessed the influence of outbreaks, environmental factors and host species in shaping the genetic variation and structure of H. hippophaecolus by using Amplified Fragment Length Polymorphism (AFLP) markers. We rejected the hypothesis that outbreak-associated genetic divergence exist, as evidenced by genetic clusters containing a combination of populations from historical outbreak areas, as well as non-outbreak areas. Although a small number of markers (4 of 933 loci) were identified as candidates under selection in response to population densities. H. hippophaecolus also did not follow an isolation-by-distance pattern. We rejected the hypothesis that outbreak and drought events were driving the genetic structure of H. hippophaecolus. Rather, the genetic structure appears to be influenced by various confounding bio-geographical factors. There were detectable genetic differences between H. hippophaecolus occupying different host trees from within the same geographic location. Host-associated genetic divergence should be confirmed by further investigation. PMID:22291983

Mitochondrial dysfunction in alveolar and white matter developmental failure in premature infants

PubMed Central

Ten, Vadim S.

2017-01-01

At birth, some organs in premature infants are not developed enough to meet challenges of the extra-uterine life. Although growth and maturation continues after premature birth, postnatal organ development may become sluggish or even arrested, leading to organ dysfunction. There is no clear mechanistic concept of this postnatal organ developmental failure in premature neonates. This review introduces a concept-forming hypothesis: Mitochondrial bioenergetic dysfunction is a fundamental mechanism of organs maturation failure in premature infants. Data collected in support of this hypothesis are relevant to two major diseases of prematurity: white matter injury and broncho-pulmonary dysplasia. In these diseases, totally different clinical manifestations are defined by the same biological process, developmental failure of the main functional units—alveoli in the lungs and axonal myelination in the brain. Although molecular pathways regulating alveolar and white matter maturation differ, proper bioenergetic support of growth and maturation remains critical biological requirement for any actively developing organ. Literature analysis suggests that successful postnatal pulmonary and white matter development highly depends on mitochondrial function which can be inhibited by sublethal postnatal stress. In premature infants, sublethal stress results mostly in organ maturation failure without excessive cellular demise. PMID:27901512

Mitochondrial dysfunction in alveolar and white matter developmental failure in premature infants.

PubMed

Ten, Vadim S

2017-02-01

At birth, some organs in premature infants are not developed enough to meet challenges of the extra-uterine life. Although growth and maturation continues after premature birth, postnatal organ development may become sluggish or even arrested, leading to organ dysfunction. There is no clear mechanistic concept of this postnatal organ developmental failure in premature neonates. This review introduces a concept-forming hypothesis: Mitochondrial bioenergetic dysfunction is a fundamental mechanism of organs maturation failure in premature infants. Data collected in support of this hypothesis are relevant to two major diseases of prematurity: white matter injury and broncho-pulmonary dysplasia. In these diseases, totally different clinical manifestations are defined by the same biological process, developmental failure of the main functional units-alveoli in the lungs and axonal myelination in the brain. Although molecular pathways regulating alveolar and white matter maturation differ, proper bioenergetic support of growth and maturation remains critical biological requirement for any actively developing organ. Literature analysis suggests that successful postnatal pulmonary and white matter development highly depends on mitochondrial function which can be inhibited by sublethal postnatal stress. In premature infants, sublethal stress results mostly in organ maturation failure without excessive cellular demise.

Sinusoidal visuomotor tracking: intermittent servo-control or coupled oscillations?

PubMed

Russell, D M; Sternad, D

2001-12-01

In visuomotor tasks that involve accuracy demands, small directional changes in the trajectories have been taken as evidence of feedback-based error corrections. In the present study variability, or intermittency, in visuomanual tracking of sinusoidal targets was investigated. Two lines of analyses were pursued: First, the hypothesis that humans fundamentally act as intermittent servo-controllers was re-examined, probing the question of whether discontinuities in the movement trajectory directly imply intermittent control. Second, an alternative hypothesis was evaluated: that rhythmic tracking movements are generated by entrainment between the oscillations of the target and the actor, such that intermittency expresses the degree of stability. In 2 experiments, participants (N = 6 in each experiment) swung 1 of 2 different hand-held pendulums, tracking a rhythmic target that oscillated at different frequencies with a constant amplitude. In 1 line of analyses, the authors tested the intermittency hypothesis by using the typical kinematic error measures and spectral analysis. In a 2nd line, they examined relative phase and its variability, following analyses of rhythmic interlimb coordination. The results showed that visually guided corrective processes play a role, especially for slow movements. Intermittency, assessed as frequency and power components of the movement trajectory, was found to change as a function of both target frequency and the manipulandum's inertia. Support for entrainment was found in conditions in which task frequency was identical to or higher than the effector's eigenfrequency. The results suggest that it is the symmetry between task and effector that determines which behavioral regime is dominant.

Critical Insights into Cardiovascular Disease from Basic Research on the Oxidation of Phospholipids: the γ-Hydroxyalkenal Phospholipid Hypothesis

PubMed Central

Salomon, Robert G.; Gu, Xiaodong

2011-01-01

Basic research, exploring the hypothesis that γ-hydroxyalkenal phospholipids are generated in vivo through oxidative cleavage of polyunsaturated phospholipids, is delivering a bonanza of molecular mechanistic insights into cardiovascular disease. Rather than targeting a specific pathology, these studies were predicated on the presumption that a fundamental understanding of lipid oxidation is likely to provide critical insights into disease processes. This investigational approach – from the chemistry of biomolecules to disease phenotype – that complements the more common opposite paradigm, is proving remarkably productive. PMID:21870852

The missing biology in land carbon models (Invited)

NASA Astrophysics Data System (ADS)

Prentice, I. C.; Cornwell, W.; Dong, N.; Maire, V.; Wang, H.; Wright, I.

2013-12-01

Models of terrestrial carbon cycling give divergent results, and recent developments - notably the inclusion of nitrogen-carbon cycle coupling - have apparently made matters worse. More extensive benchmarking of models would be highly desirable, but is not a panacea. Problems with current models include overparameterization (assigning separate sets of parameter values for each plant functional type can easily obscure more fundamental model limitations), and the widespread persistence of incorrect paradigms to describe plant responses to environment. Next-generation models require a more sound basis in observations and theory. A possible way forward will be outlined. It will be shown how the principle of optimization by natural selection can yield testable, general hypotheses about plant function. A specific optimality hypothesis about the control of CO2 drawdown versus water loss by leaves will be shown to yield global and quantitatively verifable predictions of plant behaviour as demonstrated in field gas-exchange measurements across species from different environments, and in the global pattern of stable carbon isotope discrimination by plants. Combined with the co-limitation hypothesis for the control of photosynthetic capacity and an economic approach to the costs of nutrient acquisition, this hypothesis provides a potential foundation for a comprehensive predictive understanding of the controls of primary production on land.

Disentangling the neural mechanisms involved in Hinduism- and Buddhism-related meditations.

PubMed

Tomasino, Barbara; Chiesa, Alberto; Fabbro, Franco

2014-10-01

The most diffuse forms of meditation derive from Hinduism and Buddhism spiritual traditions. Different cognitive processes are set in place to reach these meditation states. According to an historical-philological hypothesis (Wynne, 2009) the two forms of meditation could be disentangled. While mindfulness is the focus of Buddhist meditation reached by focusing sustained attention on the body, on breathing and on the content of the thoughts, reaching an ineffable state of nothigness accompanied by a loss of sense of self and duality (Samadhi) is the main focus of Hinduism-inspired meditation. It is possible that these different practices activate separate brain networks. We tested this hypothesis by conducting an activation likelihood estimation (ALE) meta-analysis of functional magnetic resonance imaging (fMRI) studies. The network related to Buddhism-inspired meditation (16 experiments, 263 subjects, and 96 activation foci) included activations in some frontal lobe structures associated with executive attention, possibly confirming the fundamental role of mindfulness shared by many Buddhist meditations. By contrast, the network related to Hinduism-inspired meditation (8 experiments, 54 activation foci and 66 subjects) triggered a left lateralized network of areas including the postcentral gyrus, the superior parietal lobe, the hippocampus and the right middle cingulate cortex. The dissociation between anterior and posterior networks support the notion that different meditation styles and traditions are characterized by different patterns of neural activation. Copyright © 2014. Published by Elsevier Inc.

Segregation of feedforward and feedback projections in mouse visual cortex

PubMed Central

Berezovskii, Vladimir K.; Nassi, Jonathan J.; Born, Richard T.

2011-01-01

Hierarchical organization is a common feature of mammalian neocortex. Neurons that send their axons from lower to higher areas of the hierarchy are referred to as “feedforward” (FF) neurons, whereas those projecting in the opposite direction are called “feedback” (FB) neurons. Anatomical, functional and theoretical studies suggest that these different classes of projections play fundamentally different roles in perception. In primates, laminar differences in projection patterns often distinguish the two projection streams. In rodents, however, these differences are less clear, despite an established hierarchy of visual areas. Thus the rodent provides a strong test of the hypothesis that FF and FB neurons form distinct populations. We tested this hypothesis by injecting retrograde tracers into two different hierarchical levels of mouse visual cortex (areas 17 and AL) and then determining the relative proportions of double-labeled FB and FF neurons in an area intermediate to them (LM). Despite finding singly labeled neurons densely intermingled with no laminar segregation, we found few double-labeled neurons (~5% of each singly labeled population). We also examined the development of FF and FB connections. FF connections were present at the earliest time-point we examined (postnatal day two, P2), while FB connections were not detectable until P11. Our findings indicate that, even in cortices without laminar segregation of FF and FB neurons, the two projection systems are largely distinct at the neuronal level and also differ with respect to the timing of their outgrowth. PMID:21618232

DOE Office of Scientific and Technical Information (OSTI.GOV)

Juanes, Ruben

The overarching goal of this project was to develop a new continuum theory of multiphase flow in porous media. The theory follows a phase-field modeling approach, and therefore has a sound thermodynamical basis. It is a phenomenological theory in the sense that its formulation is driven by macroscopic phenomena, such as viscous instabilities during multifluid displacement. The research agenda was organized around a set of hypothesis on hitherto unexplained behavior of multiphase flow. All these hypothesis are nontrivial, and testable. Indeed, a central aspect of the project was testing each hypothesis by means of carefully-designed laboratory experiments, therefore probing themore » validity of the proposed theory. The proposed research places an emphasis on the fundamentals of flow physics, but is motivated by important energy-driven applications in earth sciences, as well as microfluidic technology.« less

Deregulation of protein translation control, a potential game-changing hypothesis for Parkinson's disease pathogenesis.

PubMed

Taymans, Jean-Marc; Nkiliza, Aurore; Chartier-Harlin, Marie-Christine

2015-08-01

Protein translation is one of the most fundamental and exquisitely controlled processes in biology, and is energetically demanding. The deregulation of this process is deleterious to cells, as demonstrated by several diseases caused by mutations in protein translation machinery. Emerging evidence now points to a role for protein translation in the pathogenesis of Parkinson's disease (PD); a debilitating neurodegenerative movement disorder. In this paper, we propose a hypothesis that protein translation machinery, PD-associated proteins and PD pathology are connected in a functional network linking cell survival to protein translation control. This hypothesis is a potential game changer in the field of the molecular pathogenesis of PD, with implications for the development of PD diagnostics and disease-modifying therapies. Copyright © 2015 Elsevier Ltd. All rights reserved.

An Approximate Approach to Automatic Kernel Selection.

PubMed

Ding, Lizhong; Liao, Shizhong

2016-02-02

Kernel selection is a fundamental problem of kernel-based learning algorithms. In this paper, we propose an approximate approach to automatic kernel selection for regression from the perspective of kernel matrix approximation. We first introduce multilevel circulant matrices into automatic kernel selection, and develop two approximate kernel selection algorithms by exploiting the computational virtues of multilevel circulant matrices. The complexity of the proposed algorithms is quasi-linear in the number of data points. Then, we prove an approximation error bound to measure the effect of the approximation in kernel matrices by multilevel circulant matrices on the hypothesis and further show that the approximate hypothesis produced with multilevel circulant matrices converges to the accurate hypothesis produced with kernel matrices. Experimental evaluations on benchmark datasets demonstrate the effectiveness of approximate kernel selection.

Depression, Antidepressants, and Neurogenesis: A Critical Reappraisal

PubMed Central

Hanson, Nicola D; Owens, Michael J; Nemeroff, Charles B

2011-01-01

The neurogenesis hypothesis of depression posits (1) that neurogenesis in the subgranular zone of the dentate gyrus is regulated negatively by stressful experiences and positively by treatment with antidepressant drugs and (2) that alterations in the rate of neurogenesis play a fundamental role in the pathology and treatment of major depression. This hypothesis is supported by important experimental observations, but is challenged by equally compelling contradictory reports. This review summarizes the phenomenon of adult hippocampal neurogenesis, the initial and continued evidence leading to the development of the neurogenesis hypothesis of depression, and the recent studies that have disputed and/or qualified those findings, to conclude that it can be affected by stress and antidepressants under certain conditions, but that these effects do not appear in all cases of psychological stress, depression, and antidepressant treatment. PMID:21937982

Project Physics Text 2, Motion in the Heavens.

ERIC Educational Resources Information Center

Harvard Univ., Cambridge, MA. Harvard Project Physics.

Astronomical fundamentals are presented in this unit of the Project Physics text for use by senior high students. The geocentric system of Ptolemy is discussed in connection with Greek concepts including Aristarchus' heliocentric hypothesis. Analyses are made of Copernicus' reexamination, leading to Tycho's observations and compromise system. A…

Joint Drumming: Social Context Facilitates Synchronization in Preschool Children

ERIC Educational Resources Information Center

Kirschner, Sebastian; Tomasello, Michael

2009-01-01

The human capacity to synchronize body movements to an external acoustic beat enables uniquely human behaviors such as music making and dancing. By hypothesis, these first evolved in human cultures as fundamentally social activities. We therefore hypothesized that children would spontaneously synchronize their body movements to an external beat at…

Insights into the mechanisms and the emergence of sex-differences in pain.

PubMed

Melchior, Meggane; Poisbeau, Pierrick; Gaumond, Isabelle; Marchand, Serge

2016-12-03

Recent studies describe sex and gender as critical factors conditioning the experience of pain and the strategies to respond to it. It is now clear that men and women have different physiological and behavioral responses to pain. Some pathological pain states are also highly sex-specific. This clinical observation has been often verified with animal studies which helped to decipher the mechanisms underlying the observed female hyper-reactivity and hyper-sensitivity to pain states. The role of gonadal hormones in the modulation of pain responses has been a straightforward hypothesis but, if pertinent in many cases, cannot fully account for this complex sensation, which includes an important cognitive component. Clinical and fundamental data are reviewed here with a special emphasis on possible developmental processes giving rise to sex-differences in pain processing. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

Affect as a Psychological Primitive

PubMed Central

Barrett, Lisa Feldman; Bliss-Moreau, Eliza

2009-01-01

In this article, we discuss the hypothesis that affect is a fundamental, psychologically irreducible property of the human mind. We begin by presenting historical perspectives on the nature of affect. Next, we proceed with a more contemporary discussion of core affect as a basic property of the mind that is realized within a broadly distributed neuronal workspace. We then present the affective circumplex, a mathematical formalization for representing core affective states, and show that this model can be used to represent individual differences in core affective feelings that are linked to meaningful variation in emotional experience. Finally, we conclude by suggesting that core affect has psychological consequences that reach beyond the boundaries of emotion, to influence learning and consciousness. PMID:20552040

The Two-Brains Hypothesis: Towards a guide for brain-brain and brain-machine interfaces.

PubMed

Goodman, G; Poznanski, R R; Cacha, L; Bercovich, D

2015-09-01

Great advances have been made in signaling information on brain activity in individuals, or passing between an individual and a computer or robot. These include recording of natural activity using implants under the scalp or by external means or the reverse feeding of such data into the brain. In one recent example, noninvasive transcranial magnetic stimulation (TMS) allowed feeding of digitalized information into the central nervous system (CNS). Thus, noninvasive electroencephalography (EEG) recordings of motor signals at the scalp, representing specific motor intention of hand moving in individual humans, were fed as repetitive transcranial magnetic stimulation (rTMS) at a maximum intensity of 2.0[Formula: see text]T through a circular magnetic coil placed flush on each of the heads of subjects present at a different location. The TMS was said to induce an electric current influencing axons of the motor cortex causing the intended hand movement: the first example of the transfer of motor intention and its expression, between the brains of two remote humans. However, to date the mechanisms involved, not least that relating to the participation of magnetic induction, remain unclear. In general, in animal biology, magnetic fields are usually the poor relation of neuronal current: generally "unseen" and if apparent, disregarded or just given a nod. Niels Bohr searched for a biological parallel to complementary phenomena of physics. Pertinently, the two-brains hypothesis (TBH) proposed recently that advanced animals, especially man, have two brains i.e., the animal CNS evolved as two fundamentally different though interdependent, complementary organs: one electro-ionic (tangible, known and accessible), and the other, electromagnetic (intangible and difficult to access) - a stable, structured and functional 3D compendium of variously induced interacting electro-magnetic (EM) fields. Research on the CNS in health and disease progresses including that on brain-brain, brain-computer and brain-robot engineering. As they grow even closer, these disciplines involve their own unique complexities, including direction by the laws of inductive physics. So the novel TBH hypothesis has wide fundamental implications, including those related to TMS. These require rethinking and renewed research engaging the fully complementary equivalence of mutual magnetic and electric field induction in the CNS and, within this context, a new mathematics of the brain to decipher higher cognitive operations not possible with current brain-brain and brain-machine interfaces. Bohr may now rest.

The Role of Noncriterial Recollection in Estimating Recollection and Familiarity

PubMed Central

Parks, Colleen M.

2007-01-01

Noncriterial recollection (ncR) is recollection of details that are irrelevant to task demands. It has been shown to elevate familiarity estimates and to be functionally equivalent to familiarity in the process dissociation procedure (Yonelinas & Jacoby, 1996). However, Toth and Parks (2006) found no ncR in older adults, and hypothesized that this absence was related to older adults’ criterial recollection deficit. To test this hypothesis, as well as whether ncR is functionally equivalent to familiarity and increases the subjective experience of familiarity, remember-know and confidence-rating methods were used to estimate recollection and familiarity with young adults, young adults in a divided-attention condition (Experiment 1), and older adults. Supporting Toth and Parks’ hypothesis, ncR was found in all groups, but was consistently larger for groups with higher criterial recollection. Response distributions and receiver-operating characteristics revealed further similarities to criterial recollection and suggested that neither the experience nor usefulness of familiarity was enhanced by ncR. Overall, the results suggest that ncR does not differ fundamentally from criterial recollection. PMID:18591986

ERP Modulation during Observation of Abstract Paintings by Franz Kline

PubMed Central

Sbriscia-Fioretti, Beatrice; Berchio, Cristina; Freedberg, David; Gallese, Vittorio; Umiltà, Maria Alessandra

2013-01-01

The aim of this study was to test the involvement of sensorimotor cortical circuits during the beholding of the static consequences of hand gestures devoid of any meaning.In order to verify this hypothesis we performed an EEG experiment presenting to participants images of abstract works of art with marked traces of brushstrokes. The EEG data were analyzed by using Event Related Potentials (ERPs). We aimed to demonstrate a direct involvement of sensorimotor cortical circuits during the beholding of these selected works of abstract art. The stimuli consisted of three different abstract black and white paintings by Franz Kline. Results verified our experimental hypothesis showing the activation of premotor and motor cortical areas during stimuli observation. In addition, abstract works of art observation elicited the activation of reward-related orbitofrontal areas, and cognitive categorization-related prefrontal areas. The cortical sensorimotor activation is a fundamental neurophysiological demonstration of the direct involvement of the cortical motor system in perception of static meaningless images belonging to abstract art. These results support the role of embodied simulation of artist’s gestures in the perception of works of art. PMID:24130693

Traces of embryogenesis are the same in monozygotic and dizygotic twins: not compatible with double ovulation.

PubMed

Boklage, Charles E

2009-06-01

Common knowledge of over a century has it that monozygotic and dizygotic twinning events occur by unrelated mechanisms: monozygotic twinning 'splits' embryos, producing anomalously re-arranged embryogenic asymmetries; dizygotic twinning begins with independent ovulations yielding undisturbed parallel embryogeneses with no expectation of departures from singleton outcomes. The anomalies statistically associated with twin births are due to the re-arranged embryos of the monozygotics. Common knowledge further requires that dizygotic pairs are dichorionic; monochorionicity is exclusive to monozygotic pairs. These are fundamental certainties in the literature of twin biology. Multiple observations contradict those common knowledge understandings. The double ovulation hypothesis of dizygotic twinning is untenable. Girl-boy twins differ subtly from all other humans of either sex, absolutely not representative of all dizygotics. Embryogenesis of dizygotic twins differs from singleton development at least as much as monozygotic embryogenesis does, and in the same ways, and the differences between singletons and twins of both zygosities represent a coherent system of re-arranged embryogenic asymmetries. Dizygotic twinning and monozygotic twinning have the same list of consequences of anomalous embryogenesis. Those include an unignorable fraction of dizygotic pairs that are in fact monochorionic, plus many more sharing co-twins' cells in tissues other than a common chorion. The idea that monozygotic and dizygotic twinning events arise from the same embryogenic mechanism is the only plausible hypothesis that might explain all of the observations.

New genetic findings lead the way to a better understanding of fundamental mechanisms of drug hypersensitivity

PubMed Central

Pirmohamed, Munir; Ostrov, David A.; Park, B. Kevin

2015-01-01

Drug hypersensitivity reactions are an important clinical problem for both health care and industry. Recent advances in genetics have identified a number of HLA alleles associated with a range of these adverse reactions predominantly affecting the skin but also other organs, such as the liver. The associations between abacavir hypersensitivity and HLA-B*57:01 and carbamazepine-induced Stevens-Johnson syndrome and HLA-B*15:02 have been implemented in clinical practice. There are many different mechanisms proposed in the pathogenesis of drug hypersensitivity reactions, including the hapten hypothesis, direct binding to T-cell receptors (the pharmacologic interaction hypothesis), and peptide-binding displacement. A problem with all the hypotheses is that they are largely based on in vitro findings, with little direct in vivo evidence. Although most studies have focused on individual mechanisms, it is perhaps more important to consider them all as being complementary, potentially occurring at the same time with the same drug in the same patient. This might at least partly account for the heterogeneity of the immune response seen in different patients. There is a need to develop novel methodologies to evaluate how the in vitro mechanisms relate to the in vivo situation and how the highly consistent genetic findings with different HLA alleles can be more consistently used for both prediction and prevention of these serious adverse reactions. PMID:26254050

Differences in the catalytic mechanisms of mesophilic and thermophilic indole-3-glycerol phosphate synthase enzymes at their adaptive temperatures.

PubMed

Zaccardi, Margot J; Mannweiler, Olga; Boehr, David D

2012-02-10

Thermophilic enzymes tend to be less catalytically-active at lower temperatures relative to their mesophilic counterparts, despite having very similar crystal structures. An often cited hypothesis for this general observation is that thermostable enzymes have evolved a more rigid tertiary structure in order to cope with their more extreme, natural environment, but they are also less flexible at lower temperatures, leading to their lower catalytic activity under mesophilic conditions. An alternative hypothesis, however, is that complementary thermophilic-mesophilic enzyme pairs simply operate through different evolutionary-optimized catalytic mechanisms. In this communication, we present evidence that while the steps of the catalytic mechanisms for mesophilic and thermophilic indole-3-glycerol phosphate synthase (IGPS) enzymes are fundamentally similar, the identity of the rate-determining step changes as a function of temperature. Our findings indicate that while product release is rate-determining at 25°C for thermophilic IGPS, near its adaptive temperature (75°C), a proton transfer event, involving a general acid, becomes rate-determining. The rate-determining steps for thermophilic and mesophilic IGPS enzymes are also different at their respective, adaptive temperatures with the mesophilic IGPS-catalyzed reaction being rate-limited before irreversible CO2 release, and the thermophilic IGPS-catalyzed reaction being rate limited afterwards. Copyright © 2012 Elsevier Inc. All rights reserved.

Discriminating Simulated Vocal Tremor Source Using Amplitude Modulation Spectra

PubMed Central

Carbonell, Kathy M.; Lester, Rosemary A.; Story, Brad H.; Lotto, Andrew J.

2014-01-01

Objectives/Hypothesis Sources of vocal tremor are difficult to categorize perceptually and acoustically. This paper describes a preliminary attempt to discriminate vocal tremor sources through the use of spectral measures of the amplitude envelope. The hypothesis is that different vocal tremor sources are associated with distinct patterns of acoustic amplitude modulations. Study Design Statistical categorization methods (discriminant function analysis) were used to discriminate signals from simulated vocal tremor with different sources using only acoustic measures derived from the amplitude envelopes. Methods Simulations of vocal tremor were created by modulating parameters of a vocal fold model corresponding to oscillations of respiratory driving pressure (respiratory tremor), degree of vocal fold adduction (adductory tremor) and fundamental frequency of vocal fold vibration (F0 tremor). The acoustic measures were based on spectral analyses of the amplitude envelope computed across the entire signal and within select frequency bands. Results The signals could be categorized (with accuracy well above chance) in terms of the simulated tremor source using only measures of the amplitude envelope spectrum even when multiple sources of tremor were included. Conclusions These results supply initial support for an amplitude-envelope based approach to identify the source of vocal tremor and provide further evidence for the rich information about talker characteristics present in the temporal structure of the amplitude envelope. PMID:25532813

A new look at the Dynamic Similarity Hypothesis: the importance of swing phase.

PubMed

Raichlen, David A; Pontzer, Herman; Shapiro, Liza J

2013-01-01

The Dynamic Similarity Hypothesis (DSH) suggests that when animals of different size walk at similar Froude numbers (equal ratios of inertial and gravitational forces) they will use similar size-corrected gaits. This application of similarity theory to animal biomechanics has contributed to fundamental insights in the mechanics and evolution of a diverse set of locomotor systems. However, despite its popularity, many mammals fail to walk with dynamically similar stride lengths, a key element of gait that determines spontaneous speed and energy costs. Here, we show that the applicability of the DSH is dependent on the inertial forces examined. In general, the inertial forces are thought to be the centripetal force of the inverted pendulum model of stance phase, determined by the length of the limb. If instead we model inertial forces as the centripetal force of the limb acting as a suspended pendulum during swing phase (determined by limb center of mass position), the DSH for stride length variation is fully supported. Thus, the DSH shows that inter-specific differences in spatial kinematics are tied to the evolution of limb mass distribution patterns. Selection may act on morphology to produce a given stride length, or alternatively, stride length may be a "spandrel" of selection acting on limb mass distribution.

Basic biostatistics for post-graduate students

PubMed Central

Dakhale, Ganesh N.; Hiware, Sachin K.; Shinde, Abhijit T.; Mahatme, Mohini S.

2012-01-01

Statistical methods are important to draw valid conclusions from the obtained data. This article provides background information related to fundamental methods and techniques in biostatistics for the use of postgraduate students. Main focus is given to types of data, measurement of central variations and basic tests, which are useful for analysis of different types of observations. Few parameters like normal distribution, calculation of sample size, level of significance, null hypothesis, indices of variability, and different test are explained in detail by giving suitable examples. Using these guidelines, we are confident enough that postgraduate students will be able to classify distribution of data along with application of proper test. Information is also given regarding various free software programs and websites useful for calculations of statistics. Thus, postgraduate students will be benefitted in both ways whether they opt for academics or for industry. PMID:23087501

Hypothesis Testing as an Act of Rationality

NASA Astrophysics Data System (ADS)

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.

Testing the Role of Recollision in N2+ Air Lasing

NASA Astrophysics Data System (ADS)

Britton, Mathew; Laferrière, Patrick; Ko, Dong Hyuk; Li, Zhengyan; Kong, Fanqi; Brown, Graham; Naumov, Andrei; Zhang, Chunmei; Arissian, Ladan; Corkum, P. B.

2018-03-01

It has been known for many years that during filamentation of femtosecond light pulses in air, gain is observed on the B to X transition in N2+ . While the gain mechanism remains unclear, it has been proposed that recollision, a process that is fundamental to much of strong field science, is critical for establishing gain. We probe this hypothesis by directly comparing the influence of the ellipticity of the pump light on gain in air filaments. Then, we decouple filamentation from gain by measuring the gain in a thin gas jet that we also use for high harmonic generation. The latter allows us to compare the dependence of the gain on the ellipticity of the pump with the dependence of the high harmonic signal on the ellipticity of the fundamental. We find that gain and harmonic generation have very different behavior in both filaments and in the jet. In fact, in a jet we even measure gain with circular polarization. Thus, we establish that recollision does not play a significant role in creating the inversion.

The hydraulic limitation hypothesis revisited.

PubMed

Ryan, Michael G; Phillips, Nathan; Bond, Barbara J

2006-03-01

We proposed the hydraulic limitation hypothesis (HLH) as a mechanism to explain universal patterns in tree height, and tree and stand biomass growth: height growth slows down as trees grow taller, maximum height is lower for trees of the same species on resource-poor sites and annual wood production declines after canopy closure for even-aged forests. Our review of 51 studies that measured one or more of the components necessary for testing the hypothesis showed that taller trees differ physiologically from shorter, younger trees. Stomatal conductance to water vapour (g(s)), photosynthesis (A) and leaf-specific hydraulic conductance (K L) are often, but not always, lower in taller trees. Additionally, leaf mass per area is often greater in taller trees, and leaf area:sapwood area ratio changes with tree height. We conclude that hydraulic limitation of gas exchange with increasing tree size is common, but not universal. Where hydraulic limitations to A do occur, no evidence supports the original expectation that hydraulic limitation of carbon assimilation is sufficient to explain observed declines in wood production. Any limit to height or height growth does not appear to be related to the so-called age-related decline in wood production of forests after canopy closure. Future work on this problem should explicitly link leaf or canopy gas exchange with tree and stand growth, and consider a more fundamental assumption: whether tree biomass growth is limited by carbon availability.

Seasonal and Regional Variability in North Pacific Upper-Ocean Turbulence

NASA Astrophysics Data System (ADS)

Najjar, R.; Creedon, R.; Cronin, M. F.

2016-02-01

Turbulent diffusion at marine mixed layer base (MLB) plays a fundamental role in the transport of energy between the upper and abyssal ocean. Recent investigations of North Pacific mooring data at Ocean Climate Stations (OCS) Papa (50.1N,144.9W) and KEO (32.3N,144.6E) suggest seasonal and regional variability in thermal diffusivity (κT). In this investigation, it is hypothesized that these observed differences in κT are directly associated with synoptic variability in net surface heat flux (Q0), surface wind stress (τ), mixed layer depth (h), and density stratification at MLB (∂zσ|-h). To test this hypothesis, daily-averaged time series of κT are regressed against those of Q0, τ, h, and ∂zσ|-h at both Papa and KEO over a six year time period (2007-2013). Seasonality of each time series is removed before regression to capture synoptic variability of each variable. Preliminary results of the regression analysis suggest statistically significant correlations between κT and all forcing parameters at both mooring sites. These correlations have well-determined orders of magnitude and signs consistent with the hypothesis. As a result, differences in κT between Papa and KEO may be recast in terms of differences in their correlation coefficients. In order to continue investigation of these parameters and their effects on mean seasonal differences between the two regions, these results will be compared with turbulence predicted by the K-Profile Parameterization ocean turbulence model.

An Analysis of Social Capital and Environmental Management of Higher Education Institutions

ERIC Educational Resources Information Center

Evangelinos, Konstantinos I.; Jones, Nikoleta

2009-01-01

Purpose: The purpose of this paper is to analyse the importance of the theory of social capital for the challenges presented during environmental management initiatives in higher education institutions (HEIs). In particular, the paper utilises the fundamental components of social capital theory and assesses a hypothesis that higher stocks of…

What are you trying to learn? Study designs and the appropriate analysis for your research question

USDA-ARS?s Scientific Manuscript database

One fundamental necessity in the entire process of a well-performed study is the experimental design. A well-designed study can help researchers understand and have confidence in their results and analyses, and additionally the agreement or disagreement with the stated hypothesis. This well-designed...

Resilience of diversity-disease risk interactions following wildfire disturbance

Treesearch

Devon A. Gaydos; Krishna Pacifici; Ross K. Meentemeyer; David. M. Rizzo

2017-01-01

The potential for biodiversity to mitigate risk of infectious diseases in ecological communities – known as the diversity-disease risk hypothesis – is fundamental to understanding links between landscape change and environmental health of forests affected by sudden oak death (SOD). Previous research of the Phytophthora ramorum pathosystem...

Sleep EEG Changes during Adolescence: An Index of a Fundamental Brain Reorganization

ERIC Educational Resources Information Center

Feinberg, Irwin; Campbell, Ian G.

2010-01-01

Delta (1-4 Hz) EEG power in non-rapid eye movement (NREM) sleep declines massively during adolescence. This observation stimulated the hypothesis that during adolescence the human brain undergoes an extensive reorganization driven by synaptic elimination. The parallel declines in synaptic density, delta wave amplitude and cortical metabolic rate…

Benjamin Franklin's Pictorial Representations of the British Colonies in America: A Study in Rhetorical Iconology.

ERIC Educational Resources Information Center

Olson, Lester C.

1987-01-01

Investigates the underlying reasons for the fundamental shift in Benjamin Franklin's portrayals of the British colonies in America. Explores the hypothesis that "Magna Britannia" was both a deliberative work directed toward the British Parliament and an apologetic work directed toward conservatives in the colonial public. Also discusses…

A fundamental dispute: A discussion of "On some fundamentals of igneous petrology" by Bruce D. Marsh, Contributions to Mineralogy and Petrology (2013) 166: 665-690

NASA Astrophysics Data System (ADS)

Latypov, Rais; Morse, Tony; Robins, Brian; Wilson, Richard; Cawthorn, Grant; Tegner, Christian; Holness, Marian; Lesher, Charles; Barnes, Steve; O'Driscoll, Brian; Veksler, Ilya; Higgins, Michael; Wilson, Allan; Namur, Olivier; Chistyakova, Sofya; Naslund, Richard; Thy, Peter

2015-02-01

Marsh (Contrib Miner Petrol 166:665-690, 2013) again claims that crystal-free basalt magmas are unable to differentiate in crustal magma chambers and regards layered intrusions as primarily due to the repeated emplacement of crystal suspensions. He ignores an earlier critique of his unconventional inferences (Latypov, J Petrol 50:1047-1069, 2009) as well as a wealth of petrographic, geochemical and experimental evidence supporting the dominant role of fractional crystallization in the solidification of layered intrusions. Most tellingly, the cryptic variations preserved in the Skaergaard and many other basaltic layered intrusions would require an exceedingly implausible sequence of phenocrystic magmas but are wholly consistent with in situ fractional crystallization. A major flaw in Marsh's hypothesis is that it dismisses progressive fractional crystallization within any magma chamber and hence prohibits the formation of crystal slurries with phenocrysts and melts that change systematically in composition in any feeder system. This inherent attribute of the hypothesis excludes the formation of layered intrusions anywhere.

To Do or Not to Do: Dopamine, Affordability and the Economics of Opportunity.

PubMed

Beeler, Jeff A; Mourra, Devry

2018-01-01

Five years ago, we introduced the thrift hypothesis of dopamine (DA), suggesting that the primary role of DA in adaptive behavior is regulating behavioral energy expenditure to match the prevailing economic conditions of the environment. Here we elaborate that hypothesis with several new ideas. First, we introduce the concept of affordability, suggesting that costs must necessarily be evaluated with respect to the availability of resources to the organism, which computes a value not only for the potential reward opportunity, but also the value of resources expended. Placing both costs and benefits within the context of the larger economy in which the animal is functioning requires consideration of the different timescales against which to compute resource availability, or average reward rate. Appropriate windows of computation for tracking resources requires corresponding neural substrates that operate on these different timescales. In discussing temporal patterns of DA signaling, we focus on a neglected form of DA plasticity and adaptation, changes in the physical substrate of the DA system itself, such as up- and down-regulation of receptors or release probability. We argue that changes in the DA substrate itself fundamentally alter its computational function, which we propose mediates adaptations to longer temporal horizons and economic conditions. In developing our hypothesis, we focus on DA D2 receptors (D2R), arguing that D2R implements a form of "cost control" in response to the environmental economy, serving as the "brain's comptroller". We propose that the balance between the direct and indirect pathway, regulated by relative expression of D1 and D2 DA receptors, implements affordability. Finally, as we review data, we discuss limitations in current approaches that impede fully investigating the proposed hypothesis and highlight alternative, more semi-naturalistic strategies more conducive to neuroeconomic investigations on the role of DA in adaptive behavior.

To Do or Not to Do: Dopamine, Affordability and the Economics of Opportunity

PubMed Central

Beeler, Jeff A.; Mourra, Devry

2018-01-01

Five years ago, we introduced the thrift hypothesis of dopamine (DA), suggesting that the primary role of DA in adaptive behavior is regulating behavioral energy expenditure to match the prevailing economic conditions of the environment. Here we elaborate that hypothesis with several new ideas. First, we introduce the concept of affordability, suggesting that costs must necessarily be evaluated with respect to the availability of resources to the organism, which computes a value not only for the potential reward opportunity, but also the value of resources expended. Placing both costs and benefits within the context of the larger economy in which the animal is functioning requires consideration of the different timescales against which to compute resource availability, or average reward rate. Appropriate windows of computation for tracking resources requires corresponding neural substrates that operate on these different timescales. In discussing temporal patterns of DA signaling, we focus on a neglected form of DA plasticity and adaptation, changes in the physical substrate of the DA system itself, such as up- and down-regulation of receptors or release probability. We argue that changes in the DA substrate itself fundamentally alter its computational function, which we propose mediates adaptations to longer temporal horizons and economic conditions. In developing our hypothesis, we focus on DA D2 receptors (D2R), arguing that D2R implements a form of “cost control” in response to the environmental economy, serving as the “brain’s comptroller”. We propose that the balance between the direct and indirect pathway, regulated by relative expression of D1 and D2 DA receptors, implements affordability. Finally, as we review data, we discuss limitations in current approaches that impede fully investigating the proposed hypothesis and highlight alternative, more semi-naturalistic strategies more conducive to neuroeconomic investigations on the role of DA in adaptive behavior. PMID:29487508

Detection of semi-volatile organic compounds in permeable ...

EPA Pesticide Factsheets

Abstract The Edison Environmental Center (EEC) has a research and demonstration permeable parking lot comprised of three different permeable systems: permeable asphalt, porous concrete and interlocking concrete permeable pavers. Water quality and quantity analysis has been ongoing since January, 2010. This paper describes a subset of the water quality analysis, analysis of semivolatile organic compounds (SVOCs) to determine if hydrocarbons were in water infiltrated through the permeable surfaces. SVOCs were analyzed in samples collected from 11 dates over a 3 year period, from 2/8/2010 to 4/1/2013.Results are broadly divided into three categories: 42 chemicals were never detected; 12 chemicals (11 chemical test) were detected at a rate of less than 10% or less; and 22 chemicals were detected at a frequency of 10% or greater (ranging from 10% to 66.5% detections). Fundamental and exploratory statistical analyses were performed on these latter analyses results by grouping results by surface type. The statistical analyses were limited due to low frequency of detections and dilutions of samples which impacted detection limits. The infiltrate data through three permeable surfaces were analyzed as non-parametric data by the Kaplan-Meier estimation method for fundamental statistics; there were some statistically observable difference in concentration between pavement types when using Tarone-Ware Comparison Hypothesis Test. Additionally Spearman Rank order non-parame

Humans recognize emotional arousal in vocalizations across all classes of terrestrial vertebrates: evidence for acoustic universals.

PubMed

Filippi, Piera; Congdon, Jenna V; Hoang, John; Bowling, Daniel L; Reber, Stephan A; Pašukonis, Andrius; Hoeschele, Marisa; Ocklenburg, Sebastian; de Boer, Bart; Sturdy, Christopher B; Newen, Albert; Güntürkün, Onur

2017-07-26

Writing over a century ago, Darwin hypothesized that vocal expression of emotion dates back to our earliest terrestrial ancestors. If this hypothesis is true, we should expect to find cross-species acoustic universals in emotional vocalizations. Studies suggest that acoustic attributes of aroused vocalizations are shared across many mammalian species, and that humans can use these attributes to infer emotional content. But do these acoustic attributes extend to non-mammalian vertebrates? In this study, we asked human participants to judge the emotional content of vocalizations of nine vertebrate species representing three different biological classes-Amphibia, Reptilia (non-aves and aves) and Mammalia. We found that humans are able to identify higher levels of arousal in vocalizations across all species. This result was consistent across different language groups (English, German and Mandarin native speakers), suggesting that this ability is biologically rooted in humans. Our findings indicate that humans use multiple acoustic parameters to infer relative arousal in vocalizations for each species, but mainly rely on fundamental frequency and spectral centre of gravity to identify higher arousal vocalizations across species. These results suggest that fundamental mechanisms of vocal emotional expression are shared among vertebrates and could represent a homologous signalling system. © 2017 The Author(s).

Multi-segmental movements as a function of experience in karate.

PubMed

Zago, Matteo; Codari, Marina; Iaia, F Marcello; Sforza, Chiarella

2017-08-01

Karate is a martial art that partly depends on subjective scoring of complex movements. Principal component analysis (PCA)-based methods can identify the fundamental synergies (principal movements) of motor system, providing a quantitative global analysis of technique. In this study, we aimed at describing the fundamental multi-joint synergies of a karate performance, under the hypothesis that the latter are skilldependent; estimate karateka's experience level, expressed as years of practice. A motion capture system recorded traditional karate techniques of 10 professional and amateur karateka. At any time point, the 3D-coordinates of body markers produced posture vectors that were normalised, concatenated from all karateka and submitted to a first PCA. Five principal movements described both gross movement synergies and individual differences. A second PCA followed by linear regression estimated the years of practice using principal movements (eigenpostures and weighting curves) and centre of mass kinematics (error: 3.71 years; R2 = 0.91, P ≪ 0.001). Principal movements and eigenpostures varied among different karateka and as functions of experience. This approach provides a framework to develop visual tools for the analysis of motor synergies in karate, allowing to detect the multi-joint motor patterns that should be restored after an injury, or to be specifically trained to increase performance.

Distress sounds of thorny catfishes emitted underwater and in air: characteristics and potential significance.

PubMed

Knight, Lisa; Ladich, Friedrich

2014-11-15

Thorny catfishes produce stridulation (SR) sounds using their pectoral fins and drumming (DR) sounds via a swimbladder mechanism in distress situations when hand held in water and in air. It has been argued that SR and DR sounds are aimed at different receivers (predators) in different media. The aim of this study was to analyse and compare sounds emitted in both air and water in order to test different hypotheses on the functional significance of distress sounds. Five representatives of the family Doradidae were investigated. Fish were hand held and sounds emitted in air and underwater were recorded (number of sounds, sound duration, dominant and fundamental frequency, sound pressure level and peak-to-peak amplitudes). All species produced SR sounds in both media, but DR sounds could not be recorded in air for two species. Differences in sound characteristics between media were small and mainly limited to spectral differences in SR. The number of sounds emitted decreased over time, whereas the duration of SR sounds increased. The dominant frequency of SR and the fundamental frequency of DR decreased and sound pressure level of SR increased with body size across species. The hypothesis that catfish produce more SR sounds in air and more DR sounds in water as a result of different predation pressure (birds versus fish) could not be confirmed. It is assumed that SR sounds serve as distress sounds in both media, whereas DR sounds might primarily be used as intraspecific communication signals in water in species possessing both mechanisms. © 2014. Published by The Company of Biologists Ltd.

Multifunctional and Context-Dependent Control of Vocal Acoustics by Individual Muscles

PubMed Central

Srivastava, Kyle H.; Elemans, Coen P.H.

2015-01-01

The relationship between muscle activity and behavioral output determines how the brain controls and modifies complex skills. In vocal control, ensembles of muscles are used to precisely tune single acoustic parameters such as fundamental frequency and sound amplitude. If individual vocal muscles were dedicated to the control of single parameters, then the brain could control each parameter independently by modulating the appropriate muscle or muscles. Alternatively, if each muscle influenced multiple parameters, a more complex control strategy would be required to selectively modulate a single parameter. Additionally, it is unknown whether the function of single muscles is fixed or varies across different vocal gestures. A fixed relationship would allow the brain to use the same changes in muscle activation to, for example, increase the fundamental frequency of different vocal gestures, whereas a context-dependent scheme would require the brain to calculate different motor modifications in each case. We tested the hypothesis that single muscles control multiple acoustic parameters and that the function of single muscles varies across gestures using three complementary approaches. First, we recorded electromyographic data from vocal muscles in singing Bengalese finches. Second, we electrically perturbed the activity of single muscles during song. Third, we developed an ex vivo technique to analyze the biomechanical and acoustic consequences of single-muscle perturbations. We found that single muscles drive changes in multiple parameters and that the function of single muscles differs across vocal gestures, suggesting that the brain uses a complex, gesture-dependent control scheme to regulate vocal output. PMID:26490859

Knowledge dimensions in hypothesis test problems

NASA Astrophysics Data System (ADS)

Krishnan, Saras; Idris, Noraini

2012-05-01

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

Interstellar colonization and the zoo hypothesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, E.M.

Michael Hart and others have pointed out that current estimates of the number of technological civilizations arisen in the Galaxy since its formation is in fundamental conflict with the expectation that such a civilization could colonize and utilize the entire Galaxy in 10 to 20 million years. This dilemma can be called Hart's paradox. Resolution of the paradox requires that one or more of the following are true: we are the Galaxy's first technical civilization; interstellar travel is immensely impractical or simply impossible; technological civilizations are very short-lived; or we inhabit a wildnerness preserve. The latter is the zoo hypothesis.more » (GHT)« less

The missing link between hydrogenosomes and mitochondria.

PubMed

Martin, William

2005-10-01

Mitochondria typically respire oxygen and possess a small DNA genome. But among various groups of oxygen-shunning eukaryotes, typical mitochondria are often lacking, organelles called hydrogenosomes being found instead. Like mitochondria, hydrogenosomes are surrounded by a double-membrane, produce ATP and sometimes even have cristae. In contrast to mitochondria, hydrogenosomes produce molecular hydrogen through fermentations, lack cytochromes and usually lack DNA. Hydrogenosomes do not fit into the conceptual mold cast by the classical endosymbiont hypothesis about the nature of mitochondria. Accordingly, ideas about their evolutionary origins have focussed on the differences between the two organelles instead of their commonalities. Are hydrogenosomes fundamentally different from mitochondria, the result of a different endosymbiosis? Or are our concepts about the mitochondrial archetype simply too narrow? A new report has uncovered DNA in the hydrogenosomes of anaerobic ciliates. The sequences show that these hydrogenosomes are, without a doubt, mitochondria in the evolutionary sense, even though they differ from typical mitochondria in various biochemical properties. The new findings are a benchmark for our understanding of hydrogenosome origins.

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

PubMed

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

2014-01-01

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

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

PubMed Central

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

2014-01-01

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

The Anatomy of the Long Tail of Consumer Demand

NASA Astrophysics Data System (ADS)

Broder, Andrei

The long tail of consumer demand is consistent with two fundamentally different theories. The first, and more popular hypothesis, is that a majority of consumers have similar tastes and only few have any interest in niche content; the second, is that everyone is a bit eccentric, consuming both popular and niche products. By examining extensive data on user preferences for movies, music, web search, and web browsing, we found overwhelming support for the latter theory. Our investigation suggests an additional factor in the success of "infinite-inventory" retailers such as Netflix and Amazon: besides the significant revenue obtained from tail sales, tail availability may boost head sales by offering consumers the convenience of "one-stop shopping" for both their mainstream and niche interests.

The politics of adjustment and lifelong education: The case of Argentina

NASA Astrophysics Data System (ADS)

Sirvent, Maria Teresa

1994-05-01

This article seeks to indicate some of the aspects of lifelong education in Argentina. Empirical evidence is found for the hypothesis that continuing education reproduces and reinforces social differences. Secondly, the article identifies some of the contradictions in the present socio-economic and political context of the country, which are posing new challenges to critical and participatory lifelong education. Educational practice is having to respond to a model of society which derives from neo-conservative practices in the economic, social and educational spheres. The article is fundamentally descriptive. Qualitative and quantitative data refer to potential demand, actual demand and social demand for lifelong education. The article concludes with some reflections on lifelong education as a global policy confronting a historical crisis situation.

Adapted to Roar: Functional Morphology of Tiger and Lion Vocal Folds

PubMed Central

Klemuk, Sarah A.; Riede, Tobias; Walsh, Edward J.; Titze, Ingo R.

2011-01-01

Vocal production requires active control of the respiratory system, larynx and vocal tract. Vocal sounds in mammals are produced by flow-induced vocal fold oscillation, which requires vocal fold tissue that can sustain the mechanical stress during phonation. Our understanding of the relationship between morphology and vocal function of vocal folds is very limited. Here we tested the hypothesis that vocal fold morphology and viscoelastic properties allow a prediction of fundamental frequency range of sounds that can be produced, and minimal lung pressure necessary to initiate phonation. We tested the hypothesis in lions and tigers who are well-known for producing low frequency and very loud roaring sounds that expose vocal folds to large stresses. In histological sections, we found that the Panthera vocal fold lamina propria consists of a lateral region with adipocytes embedded in a network of collagen and elastin fibers and hyaluronan. There is also a medial region that contains only fibrous proteins and hyaluronan but no fat cells. Young's moduli range between 10 and 2000 kPa for strains up to 60%. Shear moduli ranged between 0.1 and 2 kPa and differed between layers. Biomechanical and morphological data were used to make predictions of fundamental frequency and subglottal pressure ranges. Such predictions agreed well with measurements from natural phonation and phonation of excised larynges, respectively. We assume that fat shapes Panthera vocal folds into an advantageous geometry for phonation and it protects vocal folds. Its primary function is probably not to increase vocal fold mass as suggested previously. The large square-shaped Panthera vocal fold eases phonation onset and thereby extends the dynamic range of the voice. PMID:22073246

Baryonic dark matter

NASA Technical Reports Server (NTRS)

Silk, Joseph

1991-01-01

Both canonical primordial nucleosynthesis constraints and large-scale structure measurements, as well as observations of the fundamental cosmological parameters, appear to be consistent with the hypothesis that the universe predominantly consists of baryonic dark matter (BDM). The arguments for BDM to consist of compact objects that are either stellar relics or substellar objects are reviewed. Several techniques for searching for halo BDM are described.

Should Mathematics Be a Mandatory Fundamental Component of Any IT Discipline?

ERIC Educational Resources Information Center

Eid, Chaker; Millham, Richard

2013-01-01

In this paper, we investigate whether and how mathematics factors into students' performance in IT learning. The involved cognitive levels of students learning mathematics and hence problem solving, are correlated to how well they are able to transpose their knowledge and apply it to problem solving in the IT field(s). Our hypothesis is that if…

The Effects of Catholic Schooling on Civic Participation. CIRCLE Working Paper 09

ERIC Educational Resources Information Center

Dee, Thomas S.

2003-01-01

The United States has an extensive network of publicly financed and managed schools and provides almost no financial support to private schools. One of the most fundamental justifications for the status quo is the hypothesis that the regulation of private schools cannot adequately ensure that the desired social benefits of schooling will be…

Nutritional and other types of oedema, albumin, complex carbohydrates and the interstitium - a response to Malcolm Coulthard's hypothesis: Oedema in kwashiorkor is caused by hypo-albuminaemia.

PubMed

Golden, Michael Henry

2015-05-01

The various types of oedema in man are considered in relation to Starling's hypothesis of fluid movement from capillaries, with the main emphasis on nutritional oedema and the nephrotic syndrome in children. It is concluded that each condition has sufficient anomalous findings to render Starling's hypothesis untenable. The finding that the endothelial glycocalyx is key to control of fluid movement from and into the capillaries calls for complete revision of our understanding of oedema formation. The factors so far known to affect the function of the glycocalyx are reviewed. As these depend upon sulphated proteoglycans and other glycosaminoglycans, the argument is advanced that the same abnormalities will extend to the interstitial space and that kwashiorkor is fundamentally related to a defect in sulphur metabolism which can explain all the clinical features of the condition, including the formation of oedema.

Theoretical aspects and the experience of studying spectra of low-frequency microseisms

NASA Astrophysics Data System (ADS)

Birialtsev, E.; Vildanov, A.; Eronina, E.; Rizhov, D.; Rizhov, V.; Sharapov, I.

2009-04-01

The appearance of low-frequency spectral anomalies in natural microseismic noise over oil and gas deposits is observed since 1989 in different oil and gas regions (S. Arutunov, S. Dangel, G. Goloshubin). Several methods of prospecting and exploration of oil and gas deposits based on this effect (NTK ANCHAR, Spectraseis AG). There are several points of view (S. Arutunov, E. Birialtsev, Y. Podladchikov) about the physical model of effect which are based on fundamentally different geophysical mechanisms. One of them is based on the hypothesis of generation of the microseismic noise in to an oil and gas reservoir. Another point of view is based on the mechanism of the filtering microseismic noise in the geological medium where oil and gas reservoir is the contrast layer. For the first hypothesis an adequate quantity physical-mathematical model is absent. Second hypothesis has a discrepancy of distribution energy on theoretical calculated frequencies of waveguides «ground surface - oil deposit» eigenmodes. The fundamental frequency (less than 1 Hz for most cases) should have a highest amplitude as opposed to the regular observation range is 1-10 Hz. During 2005-2008 years by specialists of «Gradient» JSC were processed microsesmic signals from more 50 geological objects. The parameters of low-frequency anomalies were compared with medium properties (porosity, saturation and viscosity) defined according to drilling, allowed to carry out a statistical analysis and to establish some correlation. This paper presents results of theoretical calculation of spectra of microseisms in the zone of oil and gas deposits by mathematical modeling of propagation of seismic waves and comparing spectra of model microseisms with actually observed. Mathematical modeling of microseismic vibrations spectra showed good correlation of theoretical spectra and observed in practice. This is proof the applicability of microseismic methods of exploration for oil and gas. Correlation between spectral parameters of microseisms and reservoir parameters were investigated on results of subsequent drilling. Dependences of the low-frequency seismic signal from collecting properties of the reservoir which have been identified indicate that the change in the spectrum of microseisms occurs when changing filtration and capacitive properties of the reservoir-collector. Changes of physical properties of oil also affect to spectral anomalies of the microseismic field. Obtained dependencies of the influence of a deposit and fluid parameters on spectral characteristics of microseisms are consistent with theoretical ideas about the nature of this influence. In general, performed the research allows confirming previously expressed hypothesis according the physical model of effect of low-frequency spectral anomalies in natural microseismic noise over oil and gas deposits and significantly refining the approach in the method of interpretation. Since the 2005 year the method of interpretation of microseismic spectrum anomalies which based on the hypothesis of filtering microseisms by geological medium widely are using by «Gradient» JSC on the territory of the Volga-Ural oil province. About 70 wells were drills according to results of our researches. According by results of independent experts the effectiveness of the forecasting is more 80%.

Generalized Knudsen Number for Unsteady Fluid Flow.

PubMed

Kara, V; Yakhot, V; Ekinci, K L

2017-02-17

We explore the scaling behavior of an unsteady flow that is generated by an oscillating body of finite size in a gas. If the gas is gradually rarefied, the Navier-Stokes equations begin to fail and a kinetic description of the flow becomes more appropriate. The failure of the Navier-Stokes equations can be thought to take place via two different physical mechanisms: either the continuum hypothesis breaks down as a result of a finite size effect or local equilibrium is violated due to the high rate of strain. By independently tuning the relevant linear dimension and the frequency of the oscillating body, we can experimentally observe these two different physical mechanisms. All the experimental data, however, can be collapsed using a single dimensionless scaling parameter that combines the relevant linear dimension and the frequency of the body. This proposed Knudsen number for an unsteady flow is rooted in a fundamental symmetry principle, namely, Galilean invariance.

Generalized Knudsen Number for Unsteady Fluid Flow

NASA Astrophysics Data System (ADS)

Kara, V.; Yakhot, V.; Ekinci, K. L.

2017-02-01

We explore the scaling behavior of an unsteady flow that is generated by an oscillating body of finite size in a gas. If the gas is gradually rarefied, the Navier-Stokes equations begin to fail and a kinetic description of the flow becomes more appropriate. The failure of the Navier-Stokes equations can be thought to take place via two different physical mechanisms: either the continuum hypothesis breaks down as a result of a finite size effect or local equilibrium is violated due to the high rate of strain. By independently tuning the relevant linear dimension and the frequency of the oscillating body, we can experimentally observe these two different physical mechanisms. All the experimental data, however, can be collapsed using a single dimensionless scaling parameter that combines the relevant linear dimension and the frequency of the body. This proposed Knudsen number for an unsteady flow is rooted in a fundamental symmetry principle, namely, Galilean invariance.

Developmental heterochrony and the evolution of autistic perception, cognition and behavior

PubMed Central

2013-01-01

Background Autism is usually conceptualized as a disorder or disease that involves fundamentally abnormal neurodevelopment. In the present work, the hypothesis that a suite of core autism-related traits may commonly represent simple delays or non-completion of typical childhood developmental trajectories is evaluated. Discussion A comprehensive review of the literature indicates that, with regard to the four phenotypes of (1) restricted interests and repetitive behavior, (2) short-range and long-range structural and functional brain connectivity, (3) global and local visual perception and processing, and (4) the presence of absolute pitch, the differences between autistic individuals and typically developing individuals closely parallel the differences between younger and older children. Summary The results of this study are concordant with a model of ‘developmental heterochrony’, and suggest that evolutionary extension of child development along the human lineage has potentiated and structured genetic risk for autism and the expression of autistic perception, cognition and behavior. PMID:23639054

Developmental heterochrony and the evolution of autistic perception, cognition and behavior.

PubMed

Crespi, Bernard

2013-05-02

Autism is usually conceptualized as a disorder or disease that involves fundamentally abnormal neurodevelopment. In the present work, the hypothesis that a suite of core autism-related traits may commonly represent simple delays or non-completion of typical childhood developmental trajectories is evaluated. A comprehensive review of the literature indicates that, with regard to the four phenotypes of (1) restricted interests and repetitive behavior, (2) short-range and long-range structural and functional brain connectivity, (3) global and local visual perception and processing, and (4) the presence of absolute pitch, the differences between autistic individuals and typically developing individuals closely parallel the differences between younger and older children. The results of this study are concordant with a model of 'developmental heterochrony', and suggest that evolutionary extension of child development along the human lineage has potentiated and structured genetic risk for autism and the expression of autistic perception, cognition and behavior.

Comparative study of thermochemical processes for hydrogen production from biomass fuels.

PubMed

Biagini, Enrico; Masoni, Lorenzo; Tognotti, Leonardo

2010-08-01

Different thermochemical configurations (gasification, combustion, electrolysis and syngas separation) are studied for producing hydrogen from biomass fuels. The aim is to provide data for the production unit and the following optimization of the "hydrogen chain" (from energy source selection to hydrogen utilization) in the frame of the Italian project "Filiera Idrogeno". The project focuses on a regional scale (Tuscany, Italy), renewable energies and automotive hydrogen. Decentred and small production plants are required to solve the logistic problems of biomass supply and meet the limited hydrogen infrastructures. Different options (gasification with air, oxygen or steam/oxygen mixtures, combustion, electrolysis) and conditions (varying the ratios of biomass and gas input) are studied by developing process models with uniform hypothesis to compare the results. Results obtained in this work concern the operating parameters, process efficiencies, material and energetic needs and are fundamental to optimize the entire hydrogen chain. Copyright 2010 Elsevier Ltd. All rights reserved.

Cytogenetic effect of low dose gamma-radiation in Hordeum vulgare seedlings: non-linear dose-effect relationship.

PubMed

Geras'kin, Stanislav A; Oudalova, Alla A; Kim, Jin Kyu; Dikarev, Vladimir G; Dikareva, Nina S

2007-03-01

The induction of chromosome aberrations in Hordeum vulgare germinated seeds was studied after ionizing irradiation with doses in the range of 10-1,000 mGy. The relationship between the frequency of aberrant cells and the absorbed dose was found to be nonlinear. A dose-independent plateau in the dose range from about 50 to 500 mGy was observed, where the level of cytogenetic damage was significantly different from the spontaneous level. The comparison of the goodness of the experimental data fitting with mathematical models of different complexity, using the most common quantitative criteria, demonstrated the advantage of a piecewise linear model over linear and polynomial models in approximating the frequency of cytogenetical disturbances. The results of the study support the hypothesis of indirect mechanisms of mutagenesis induced by low doses. Fundamental and applied implications of these findings are discussed.

Computational principles of syntax in the regions specialized for language: integrating theoretical linguistics and functional neuroimaging

PubMed Central

Ohta, Shinri; Fukui, Naoki; Sakai, Kuniyoshi L.

2013-01-01

The nature of computational principles of syntax remains to be elucidated. One promising approach to this problem would be to construct formal and abstract linguistic models that parametrically predict the activation modulations in the regions specialized for linguistic processes. In this article, we review recent advances in theoretical linguistics and functional neuroimaging in the following respects. First, we introduce the two fundamental linguistic operations: Merge (which combines two words or phrases to form a larger structure) and Search (which searches and establishes a syntactic relation of two words or phrases). We also illustrate certain universal properties of human language, and present hypotheses regarding how sentence structures are processed in the brain. Hypothesis I is that the Degree of Merger (DoM), i.e., the maximum depth of merged subtrees within a given domain, is a key computational concept to properly measure the complexity of tree structures. Hypothesis II is that the basic frame of the syntactic structure of a given linguistic expression is determined essentially by functional elements, which trigger Merge and Search. We then present our recent functional magnetic resonance imaging experiment, demonstrating that the DoM is indeed a key syntactic factor that accounts for syntax-selective activations in the left inferior frontal gyrus and supramarginal gyrus. Hypothesis III is that the DoM domain changes dynamically in accordance with iterative Merge applications, the Search distances, and/or task requirements. We confirm that the DoM accounts for activations in various sentence types. Hypothesis III successfully explains activation differences between object- and subject-relative clauses, as well as activations during explicit syntactic judgment tasks. A future research on the computational principles of syntax will further deepen our understanding of uniquely human mental faculties. PMID:24385957

Computational principles of syntax in the regions specialized for language: integrating theoretical linguistics and functional neuroimaging.

PubMed

Ohta, Shinri; Fukui, Naoki; Sakai, Kuniyoshi L

2013-01-01

The nature of computational principles of syntax remains to be elucidated. One promising approach to this problem would be to construct formal and abstract linguistic models that parametrically predict the activation modulations in the regions specialized for linguistic processes. In this article, we review recent advances in theoretical linguistics and functional neuroimaging in the following respects. First, we introduce the two fundamental linguistic operations: Merge (which combines two words or phrases to form a larger structure) and Search (which searches and establishes a syntactic relation of two words or phrases). We also illustrate certain universal properties of human language, and present hypotheses regarding how sentence structures are processed in the brain. Hypothesis I is that the Degree of Merger (DoM), i.e., the maximum depth of merged subtrees within a given domain, is a key computational concept to properly measure the complexity of tree structures. Hypothesis II is that the basic frame of the syntactic structure of a given linguistic expression is determined essentially by functional elements, which trigger Merge and Search. We then present our recent functional magnetic resonance imaging experiment, demonstrating that the DoM is indeed a key syntactic factor that accounts for syntax-selective activations in the left inferior frontal gyrus and supramarginal gyrus. Hypothesis III is that the DoM domain changes dynamically in accordance with iterative Merge applications, the Search distances, and/or task requirements. We confirm that the DoM accounts for activations in various sentence types. Hypothesis III successfully explains activation differences between object- and subject-relative clauses, as well as activations during explicit syntactic judgment tasks. A future research on the computational principles of syntax will further deepen our understanding of uniquely human mental faculties.

New genetic findings lead the way to a better understanding of fundamental mechanisms of drug hypersensitivity.

PubMed

Pirmohamed, Munir; Ostrov, David A; Park, B Kevin

2015-08-01

Drug hypersensitivity reactions are an important clinical problem for both health care and industry. Recent advances in genetics have identified a number of HLA alleles associated with a range of these adverse reactions predominantly affecting the skin but also other organs, such as the liver. The associations between abacavir hypersensitivity and HLA-B*57:01 and carbamazepine-induced Stevens-Johnson syndrome and HLA-B*15:02 have been implemented in clinical practice. There are many different mechanisms proposed in the pathogenesis of drug hypersensitivity reactions, including the hapten hypothesis, direct binding to T-cell receptors (the pharmacologic interaction hypothesis), and peptide-binding displacement. A problem with all the hypotheses is that they are largely based on in vitro findings, with little direct in vivo evidence. Although most studies have focused on individual mechanisms, it is perhaps more important to consider them all as being complementary, potentially occurring at the same time with the same drug in the same patient. This might at least partly account for the heterogeneity of the immune response seen in different patients. There is a need to develop novel methodologies to evaluate how the in vitro mechanisms relate to the in vivo situation and how the highly consistent genetic findings with different HLA alleles can be more consistently used for both prediction and prevention of these serious adverse reactions. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Aftershock Energy Distribution by Statistical Mechanics Approach

NASA Astrophysics Data System (ADS)

Daminelli, R.; Marcellini, A.

2015-12-01

The aim of our work is to research the most probable distribution of the energy of aftershocks. We started by applying one of the fundamental principles of statistical mechanics that, in case of aftershock sequences, it could be expressed as: the greater the number of different ways in which the energy of aftershocks can be arranged among the energy cells in phase space the more probable the distribution. We assume that each cell in phase space has the same possibility to be occupied, and that more than one cell in the phase space can have the same energy. Seeing that seismic energy is proportional to products of different parameters, a number of different combinations of parameters can produce different energies (e.g., different combination of stress drop and fault area can release the same seismic energy). Let us assume that there are gi cells in the aftershock phase space characterised by the same energy released ɛi. Therefore we can assume that the Maxwell-Boltzmann statistics can be applied to aftershock sequences with the proviso that the judgment on the validity of this hypothesis is the agreement with the data. The aftershock energy distribution can therefore be written as follow: n(ɛ)=Ag(ɛ)exp(-βɛ)where n(ɛ) is the number of aftershocks with energy, ɛ, A and β are constants. Considering the above hypothesis, we can assume g(ɛ) is proportional to ɛ. We selected and analysed different aftershock sequences (data extracted from Earthquake Catalogs of SCEC, of INGV-CNT and other institutions) with a minimum magnitude retained ML=2 (in some cases ML=2.6) and a time window of 35 days. The results of our model are in agreement with the data, except in the very low energy band, where our model resulted in a moderate overestimation.

An analysis of quantum coherent solar photovoltaic cells

NASA Astrophysics Data System (ADS)

Kirk, A. P.

2012-02-01

A new hypothesis (Scully et al., Proc. Natl. Acad. Sci. USA 108 (2011) 15097) suggests that it is possible to break the statistical physics-based detailed balance-limiting power conversion efficiency and increase the power output of a solar photovoltaic cell by using “noise-induced quantum coherence” to increase the current. The fundamental errors of this hypothesis are explained here. As part of this analysis, we show that the maximum photogenerated current density for a practical solar cell is a function of the incident spectrum, sunlight concentration factor, and solar cell energy bandgap and thus the presence of quantum coherence is irrelevant as it is unable to lead to increased current output from a solar cell.

Does paedomorphosis contribute to prairie vole monogamy?

PubMed Central

Bushyhead, Timothy; Curtis, J. Thomas

2015-01-01

We examined skull morphology in prairie voles (Microtus ochrogaster) and meadow voles (M. pennsylvanicus), two closely related species with fundamentally different mating systems, to test the hypothesis that paedomorphosis contributes to the evolution of monogamous mating systems. Using several skull measurements, we found that the overall length:width ratio of meadow vole skulls was greater than that of prairie voles suggesting that meadow vole have longer narrower skulls. We then examined which aspects of skull morphology differed between the species and found that the ratio difference was attributable primarily to longer snout length in meadow voles. Finally, we compared adult morphology in both species to that of pups and found the prairie vole, a monogamous species, displays a more juvenile-like skull morphology than does the meadow vole, a promiscuous species. These results suggest that monogamous vole species retain more juvenile-like morphology than do promiscuous species, and thus possibly retain juvenile-like behaviors that may contribute to a monogamous mating system. PMID:26594100

Does paedomorphosis contribute to prairie vole monogamy?

PubMed

Bushyhead, Timothy; Curtis, J Thomas

We examined skull morphology in prairie voles ( Microtus ochrogaster ) and meadow voles ( M. pennsylvanicus ), two closely related species with fundamentally different mating systems, to test the hypothesis that paedomorphosis contributes to the evolution of monogamous mating systems. Using several skull measurements, we found that the overall length:width ratio of meadow vole skulls was greater than that of prairie voles suggesting that meadow vole have longer narrower skulls. We then examined which aspects of skull morphology differed between the species and found that the ratio difference was attributable primarily to longer snout length in meadow voles. Finally, we compared adult morphology in both species to that of pups and found the prairie vole, a monogamous species, displays a more juvenile-like skull morphology than does the meadow vole, a promiscuous species. These results suggest that monogamous vole species retain more juvenile-like morphology than do promiscuous species, and thus possibly retain juvenile-like behaviors that may contribute to a monogamous mating system.

Pick Your Poisson: An Educational Primer for Luria and Delbrück's Classic Paper.

PubMed

Meneely, Philip M

2016-02-01

The origin of beneficial mutations is fundamentally important in understanding the processes by which natural selection works. Using phage-resistant mutants in Escherichia coli as their model for identifying the origin of beneficial mutations, Luria and Delbrück distinguished between two different hypotheses. Under the first hypothesis, which they termed "acquired immunity," the phages induced bacteria to mutate to immunity; this predicts that none of the resistant mutants were present before infection by the phages. Under the second hypothesis, termed "mutation to immunity," resistant bacteria arose from random mutations independent of the presence of the phages; this predicts that resistant bacteria were present in the population before infection by the phages. These two hypotheses could be distinguished by calculating the frequencies at which resistant mutants arose in separate cultures infected at the same time and comparing these frequencies to the theoretical results under each model. The data clearly show that mutations arise at a frequency that is independent of the presence of the phages. By inference, natural selection reveals the genetic variation that is present in a population rather than inducing or causing this variation. Copyright © 2016 by the Genetics Society of America.

Teaching Chemistry for All Its Worth: The Interaction Between Facts, Ideas, and Language in Lavoisier's and Priestley's Chemistry Practice: The Case of the Study of the Composition of Air

NASA Astrophysics Data System (ADS)

de Berg, Kevin

2014-10-01

Both Lavoisier and Priestley were committed to the role of experiment and observation in their chemistry practice. According to Lavoisier the physical sciences embody three important ingredients; facts, ideas, and language, and Priestley would not have disagreed with this. Ideas had to be consistent with the facts generated from experiment and observation and language needed to be precise and reflect the known chemistry of substances. While Priestley was comfortable with a moderate amount of hypothesis making, Lavoisier had no time for what he termed theoretical speculation about the fundamental nature of matter and avoided the use of the atomic hypothesis and Aristotle's elements in his Elements of Chemistry. In the preface to this famous work he claims he has good educational reasons for this position. While Priestley and Lavoisier used similar kinds of apparatus in their chemistry practice, they came to their task with completely different worldviews as regards the nature of chemical reactivity. This paper examines these worldviews as practiced in the famous experiment on the composition of air and the implications of this for chemistry education are considered.

Identity of Particles and Continuum Hypothesis

NASA Astrophysics Data System (ADS)

Berezin, Alexander A.

2001-04-01

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

Membrane-Based Functions in the Origin of Cellular Life

NASA Technical Reports Server (NTRS)

Chipot, Christophe; New, Michael H.; Schweighofer, Karl; Pohorille, Andrew; Wilson, Michael A.

1999-01-01

Our objective is to help explain how the earliest ancestors of contemporary cells (protocells) performed their essential functions employing only the molecules available in the protobiological milieu. Our hypothesis is that vesicles, built of amphiphilic, membrane-forming materials, emerged early in protobiological evolution and served as precursors to protocells. We further assume that the cellular functions associated with contemporary membranes, such as capturing and, transducing of energy, signaling, or sequestering organic molecules and ions, evolved in these membrane environments. An alternative hypothesis is that these functions evolved in different environments and were incorporated into membrane-bound structures at some later stage of evolution. We focus on the application of the fundamental principles of physics and chemistry to determine how they apply to the formation of a primitive, functional cell. Rather than attempting to develop specific models for cellular functions and to identify the origin of the molecules which perform these functions, our goal is to define the structural and energetic conditions that any successful model must fulfill, therefore providing physico-chemical boundaries for these models. We do this by carrying out large-scale, molecular level computer simulations on systems of interest.

Two different mechanisms support selective attention at different phases of training.

PubMed

Itthipuripat, Sirawaj; Cha, Kexin; Byers, Anna; Serences, John T

2017-06-01

Selective attention supports the prioritized processing of relevant sensory information to facilitate goal-directed behavior. Studies in human subjects demonstrate that attentional gain of cortical responses can sufficiently account for attention-related improvements in behavior. On the other hand, studies using highly trained nonhuman primates suggest that reductions in neural noise can better explain attentional facilitation of behavior. Given the importance of selective information processing in nearly all domains of cognition, we sought to reconcile these competing accounts by testing the hypothesis that extensive behavioral training alters the neural mechanisms that support selective attention. We tested this hypothesis using electroencephalography (EEG) to measure stimulus-evoked visual responses from human subjects while they performed a selective spatial attention task over the course of ~1 month. Early in training, spatial attention led to an increase in the gain of stimulus-evoked visual responses. Gain was apparent within ~100 ms of stimulus onset, and a quantitative model based on signal detection theory (SDT) successfully linked the magnitude of this gain modulation to attention-related improvements in behavior. However, after extensive training, this early attentional gain was eliminated even though there were still substantial attention-related improvements in behavior. Accordingly, the SDT-based model required noise reduction to account for the link between the stimulus-evoked visual responses and attentional modulations of behavior. These findings suggest that training can lead to fundamental changes in the way attention alters the early cortical responses that support selective information processing. Moreover, these data facilitate the translation of results across different species and across experimental procedures that employ different behavioral training regimes.

Two different mechanisms support selective attention at different phases of training

PubMed Central

Cha, Kexin; Byers, Anna; Serences, John T.

2017-01-01

Selective attention supports the prioritized processing of relevant sensory information to facilitate goal-directed behavior. Studies in human subjects demonstrate that attentional gain of cortical responses can sufficiently account for attention-related improvements in behavior. On the other hand, studies using highly trained nonhuman primates suggest that reductions in neural noise can better explain attentional facilitation of behavior. Given the importance of selective information processing in nearly all domains of cognition, we sought to reconcile these competing accounts by testing the hypothesis that extensive behavioral training alters the neural mechanisms that support selective attention. We tested this hypothesis using electroencephalography (EEG) to measure stimulus-evoked visual responses from human subjects while they performed a selective spatial attention task over the course of ~1 month. Early in training, spatial attention led to an increase in the gain of stimulus-evoked visual responses. Gain was apparent within ~100 ms of stimulus onset, and a quantitative model based on signal detection theory (SDT) successfully linked the magnitude of this gain modulation to attention-related improvements in behavior. However, after extensive training, this early attentional gain was eliminated even though there were still substantial attention-related improvements in behavior. Accordingly, the SDT-based model required noise reduction to account for the link between the stimulus-evoked visual responses and attentional modulations of behavior. These findings suggest that training can lead to fundamental changes in the way attention alters the early cortical responses that support selective information processing. Moreover, these data facilitate the translation of results across different species and across experimental procedures that employ different behavioral training regimes. PMID:28654635

Post-natal molecular adaptations in anteromedial and posterolateral bundles of the ovine anterior cruciate ligament: one structure with two parts or two distinct ligaments?

PubMed

Huebner, Kyla D; O'Brien, Etienne J O; Heard, Bryan J; Chung, May; Achari, Yamini; Shrive, Nigel G; Frank, Cyril B

2012-01-01

The human anterior cruciate ligament (ACL) is a composite structure of two anatomically distinct bundles: an anteromedial (AM) and posterolateral (PL) bundles. Tendons are often used as autografts for surgical reconstruction of ACL following severe injury. However, despite successful surgical reconstruction, some people experience re-rupture and later development of osteoarthritis. Understanding the structure and molecular makeup of normal ACL is essential for its optimal replacement. Reportedly the two bundles display different tensions throughout joint motion and may be fundamentally different. This study assessed the similarities and differences in ultrastructure and molecular composition of the AM and PL bundles to test the hypothesis that the two bundles of the ACL develop unique characteristics with maturation. ACLs from nine mature and six immature sheep were compared. The bundles were examined for mRNA and protein levels of collagen types I, III, V, and VI, and two proteoglycans. The fibril diameter composition of the two bundles was examined with transmission electron microscopy. Maturation does alter the molecular and structural composition of the two bundles of ACL. Although the PL band appears to mature slower than the AM band, no significant differences were detected between the bundles in the mature animals. We thus reject our hypothesis that the two ACL bundles are distinct. The two anatomically distinct bundles of the sheep ACL can be considered as two parts of one structure at maturity and material that would result in a structure of similar functionality can be used to replace each ACL bundle in the sheep.

Applying tribology to teeth of hoofed mammals.

PubMed

Schulz, Ellen; Calandra, Ivan; Kaiser, Thomas M

2010-01-01

Mammals inhabit all types of environments and have evolved chewing systems capable of processing a huge variety of structurally diverse food components. Surface textures of cheek teeth should thus reflect the mechanisms of wear as well as the functional traits involved. We employed surface textures parameters from ISO/DIS 25178 and scale-sensitive fractal analysis (SSFA) to quantify dental wear in herbivorous mammals at the level of an individual wear enamel facet. We evaluated cheek dentitions of two grazing ungulates: the Blue Wildebeest (Connochaetes taurinus) and the Grevy's Zebra (Equus grevyi). Both inhabit the east African grassland savanna habitat, but they belong to fundamentally different taxonomic units. We tested the hypothesis that the foregut fermenting wildebeest and the hindgut fermenting zebra show functional traits in their dentitions that relate to their specific mode of food-composition processing and digestion. In general, surface texture parameters from SSFA as well as ISO/DIS 25178 indicated that individual enamel ridges acting as crushing blades and individual wear facets of upper cheek teeth are significantly different in surface textures in the zebra when compared with the wildebeest. We interpreted the complexity and anisotropy signals to be clearly related to the brittle, dry grass component in the diet of the zebra, unlike the wildebeest, which ingests a more heterogeneous diet including fresh grass and herbs. Thus, SSFA and ISO parameters allow distinctions within the subtle dietary strategies that evolved in herbivorous ungulates with fundamentally different systematic affinities but which exploit a similar dietary niche. © 2010 Wiley Periodicals, Inc.

Evolutionary dynamics of group formation.

PubMed

Javarone, Marco Alberto; Marinazzo, Daniele

2017-01-01

Group formation is a quite ubiquitous phenomenon across different animal species, whose individuals cluster together forming communities of diverse size. Previous investigations suggest that, in general, this phenomenon might have similar underlying reasons across the interested species, despite genetic and behavioral differences. For instance improving the individual safety (e.g. from predators), and increasing the probability to get food resources. Remarkably, the group size might strongly vary from species to species, e.g. shoals of fishes and herds of lions, and sometimes even within the same species, e.g. tribes and families in human societies. Here we build on previous theories stating that the dynamics of group formation may have evolutionary roots, and we explore this fascinating hypothesis from a purely theoretical perspective, with a model using the framework of Evolutionary Game Theory. In our model we hypothesize that homogeneity constitutes a fundamental ingredient in these dynamics. Accordingly, we study a population that tries to form homogeneous groups, i.e. composed of similar agents. The formation of a group can be interpreted as a strategy. Notably, agents can form a group (receiving a 'group payoff'), or can act individually (receiving an 'individual payoff'). The phase diagram of the modeled population shows a sharp transition between the 'group phase' and the 'individual phase', characterized by a critical 'individual payoff'. Our results then support the hypothesis that the phenomenon of group formation has evolutionary roots.

What Kinds of Numbers Do Students Assign to Literal Symbols? Aspects of the Transition from Arithmetic to Algebra

ERIC Educational Resources Information Center

Christou, Konstantinos P.; Vosniadou, Stella

2012-01-01

Three experiments used multiple methods--open-ended assessments, multiple-choice questionnaires, and interviews--to investigate the hypothesis that the development of students' understanding of the concept of real variable in algebra may be influenced in fundamental ways by their initial concept of number, which seems to be organized around the…

Contrasting hydraulic strategies in two tropical lianas and their host trees

Treesearch

Daniel M. Johnson; Jean-Christophe Domec; David R. Woodruff; Katherine A. McCulloh; Frederick C. Meinzer

2013-01-01

Tropical Iiana abundance has been increasing over the past 40 yr, which has been associated with reduced rainfall. The proposed mechanism allowing lianas to thrive in dry conditions is deeper root systems than co-occurring trees, although we know very little about the fundamental hydraulic physiology of lianas. To test the hypothesis that two abundant Iiana species...

A new fundamental model of moving particle for reinterpreting Schroedinger equation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Umar, Muhamad Darwis

2012-06-20

The study of Schroedinger equation based on a hypothesis that every particle must move randomly in a quantum-sized volume has been done. In addition to random motion, every particle can do relative motion through the movement of its quantum-sized volume. On the other way these motions can coincide. In this proposed model, the random motion is one kind of intrinsic properties of the particle. The every change of both speed of randomly intrinsic motion and or the velocity of translational motion of a quantum-sized volume will represent a transition between two states, and the change of speed of randomly intrinsicmore » motion will generate diffusion process or Brownian motion perspectives. Diffusion process can take place in backward and forward processes and will represent a dissipative system. To derive Schroedinger equation from our hypothesis we use time operator introduced by Nelson. From a fundamental analysis, we find out that, naturally, we should view the means of Newton's Law F(vector sign) = ma(vector sign) as no an external force, but it is just to describe both the presence of intrinsic random motion and the change of the particle energy.« less

Deep Sequencing of RNA from Ancient Maize Kernels

PubMed Central

Rasmussen, Morten; Cappellini, Enrico; Romero-Navarro, J. Alberto; Wales, Nathan; Alquezar-Planas, David E.; Penfield, Steven; Brown, Terence A.; Vielle-Calzada, Jean-Philippe; Montiel, Rafael; Jørgensen, Tina; Odegaard, Nancy; Jacobs, Michael; Arriaza, Bernardo; Higham, Thomas F. G.; Ramsey, Christopher Bronk; Willerslev, Eske; Gilbert, M. Thomas P.

2013-01-01

The characterization of biomolecules from ancient samples can shed otherwise unobtainable insights into the past. Despite the fundamental role of transcriptomal change in evolution, the potential of ancient RNA remains unexploited – perhaps due to dogma associated with the fragility of RNA. We hypothesize that seeds offer a plausible refuge for long-term RNA survival, due to the fundamental role of RNA during seed germination. Using RNA-Seq on cDNA synthesized from nucleic acid extracts, we validate this hypothesis through demonstration of partial transcriptomal recovery from two sources of ancient maize kernels. The results suggest that ancient seed transcriptomics may offer a powerful new tool with which to study plant domestication. PMID:23326310

Suppressive mechanisms in visual motion processing: from perception to intelligence

PubMed Central

Tadin, Duje

2015-01-01

Perception operates on an immense amount of incoming information that greatly exceeds the brain's processing capacity. Because of this fundamental limitation, the ability to suppress irrelevant information is a key determinant of perceptual efficiency. Here, I will review a series of studies investigating suppressive mechanisms in visual motion processing, namely perceptual suppression of large, background-like motions. These spatial suppression mechanisms are adaptive, operating only when sensory inputs are sufficiently robust to guarantee visibility. Converging correlational and causal evidence links these behavioral results with inhibitory center-surround mechanisms, namely those in cortical area MT. Spatial suppression is abnormally weak in several special populations, including the elderly and those with schizophrenia—a deficit that is evidenced by better-than-normal direction discriminations of large moving stimuli. Theoretical work shows that this abnormal weakening of spatial suppression should result in motion segregation deficits, but direct behavioral support of this hypothesis is lacking. Finally, I will argue that the ability to suppress information is a fundamental neural process that applies not only to perception but also to cognition in general. Supporting this argument, I will discuss recent research that shows individual differences in spatial suppression of motion signals strongly predict individual variations in IQ scores. PMID:26299386

Too clean, or not too clean: the Hygiene Hypothesis and home hygiene

PubMed Central

Bloomfield, SF; Stanwell-Smith, R; Crevel, RWR; Pickup, J

2006-01-01

Summary The ‘hygiene hypothesis’ as originally formulated by Strachan, proposes that a cause of the recent rapid rise in atopic disorders could be a lower incidence of infection in early childhood, transmitted by unhygienic contact with older siblings. Use of the term ‘hygiene hypothesis’ has led to several interpretations, some of which are not supported by a broader survey of the evidence. The increase in allergic disorders does not correlate with the decrease in infection with pathogenic organisms, nor can it be explained by changes in domestic hygiene. A consensus is beginning to develop round the view that more fundamental changes in lifestyle have led to decreased exposure to certain microbial or other species, such as helminths, that are important for the development of immunoregulatory mechanisms. Although this review concludes that the relationship of the hypothesis to hygiene practice is not proven, it lends strong support to initiatives seeking to improve hygiene practice. It would however be helpful if the hypothesis were renamed, e.g. as the ‘microbial exposure’ hypothesis, or ‘microbial deprivation’ hypothesis, as proposed for instance by Bjorksten. Avoiding the term ‘hygiene’ would help focus attention on determining the true impact of microbes on atopic diseases, while minimizing risks of discouraging good hygiene practice. PMID:16630145

Tissue Bioeffects during Ultrasound-mediated Drug Delivery

NASA Astrophysics Data System (ADS)

Sutton, Jonathan

Ultrasound has been developed as both a valuable diagnostic tool and a potent promoter of beneficial tissue bioeffects for the treatment of cardiovascular disease. Vascular effects can be mediated by mechanical oscillations of circulating microbubbles, or ultrasound contrast agents, which may also encapsulate and shield a therapeutic agent in the bloodstream. Oscillating microbubbles can create stresses directly on nearby tissue or induce fluid effects that effect drug penetration into vascular tissue, lyse thrombi, or direct drugs to optimal locations for delivery. These investigations have spurred continued research into alternative therapeutic applications, such as bioactive gas delivery. This dissertation addresses a fundamental hypothesis in biomedical ultrasound: ultrasound-mediated drug delivery is capable of increasing the penetration of drugs across different physiologic barriers within the cardiovascular system, such as the vascular endothelium, blood clots, and smooth muscle cells.

Influence of Solutocapillary Convection on Macrovoid Defect Formation in Polymeric Membranes

NASA Technical Reports Server (NTRS)

Greenberg, Alan R.; Krantz, William B.; Todd, Paul

2003-01-01

The focus of this research project involved the dry-cast process for polymeric membrane formation, whereby evaporation of solvent from an initially homogeneous polymer/solvent/ nonsolvent solution results in phase separation and the formation of polymer-rich and polymer-lean phases. Under certain conditions the polymer-lean phase gives rise to very large and usually undesirable, tear-drop-shaped pores (size approx. 10 - 50 microns) termed macrovoids (MVs). Although in many cases the presence of MV pores has deleterious effects on membrane performance, there are a number of innovative applications where the presence of such pores is highly desirable. Although researchers have proposed a variety of mechanisms for MV formation over the past three decades, two main hypotheses are currently favored: one asserts that MV growth can be attributed solely to diffusion (the diffusive growth hypothesis), whereas the other states that solutocapillary convection (the SC hypothesis) at the MV interface contributes to growth. The overall goal of this research was to obtain a more comprehensive understanding of the fundamental mechanism of MV growth. This research incorporates a coupled modeling and experimental approach to test a solutocapillary convection hypothesis for the growth of macrovoid pores in polymeric membranes. Specifically, we utilized a modification of the first principles model developed by two of the PIs (ARG and WBK) for dry-cast CA membranes. For the experimental component, two separate and mutually complementary approaches were used to study MV growth. In the first, membranes cast in a zero-g environment aboard the NASA KC-135 aircraft were compared with those cast on the ground to assess the effect of the buoyancy force on membrane morphology and MV size and shape. In the second approach, videomicroscopy flow visualization (VMFV) was utilized to observe MV formation and growth in real time and to assess the effect of surface tension on the MV growth dynamics. As a result of these fundamental studies, our research group advanced a new hypothesis for MV pore development in polymeric membranes.

Beyond the hydrophobic effect: Critical function of water at biological phase boundaries--A hypothesis.

PubMed

Damodaran, Srinivasan

2015-07-01

Many life-sustaining processes in living cells occur at the membrane-water interface. The pertinent questions that need to be asked are what is the evolutionary reason for biology to choose the membrane-water interface as the site for performing and/or controlling crucial biological reactions and what is the key physical principle that is singular to the membrane-water interface that biology exploits for regulating metabolic processes in cells? In this review, a hypothesis is developed, which espouses that cells control activities of membrane-bound enzymes and receptor activated processes via manipulating the thermodynamic activity of water at the membrane-water interfacial region. In support of this hypothesis, first we establish that the surface pressure of a lipid monolayer is a direct measure of a reduction in the thermodynamic activity of interfacial water. Second, we show that the surface pressure-dependent activation/inactivation of interfacial enzymes is fundamentally related to their dependence on interfacial water activity. We extend this argument to infer that cells might manipulate activities of membrane-associated biological processes via manipulating the activity of interfacial water via localized compression or expansion of the interface. In this paper, we critically analyze literature data on mechano-activation of large pore ion channels in Escherichia coli spheroplasts and G-proteins in reconstituted lipid vesicles, and show that these pressure-induced activation processes are fundamentally and quantitatively related to changes in the thermodynamic state of interfacial water, caused by mechanical stretching of the bilayer. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparison of Methylmercury Production and Accumulation in Sediments of the Congaree and Edisto River Basins, South Carolina, 2004-06

USGS Publications Warehouse

Bradley, Paul M.; Chapelle, Francis H.; Journey, Celeste A.

2009-01-01

Fish-tissue mercury concentrations (approximately 2 micrograms per gram) in the Edisto River basin of South Carolina are among the highest recorded in the United States. Substantially lower mercury concentrations (approximately 0.2 microgram per gram) are reported in fish from the adjacent (about 30 kilometer) Congaree River basin and the Congaree National Park. In contrast, concentrations of total mercury were statistically higher in sediments from the Congaree River compared with those in sediments from the Edisto River. Furthermore, no statistically significant difference was observed in concentrations of methylmercury or net methylation potential in sediments collected from various Edisto and Congaree hydrologic settings. In both systems, the net methylation potential was low (0-0.17 nanogram per gram per day) for in-stream sediments exposed to continuously flowing water but substantially higher (about 1.8 nanograms per gram per day) in wetland sediments exposed to standing water. These results are not consistent with the hypothesis that differences in fish-tissue mercury between the Edisto and Congaree basins reflect fundamental differences in the potential for each system to methylate mercury. Rather, the significantly higher ratios of methylmercury to total mercury observed in the Edisto system suggest that the net accumulation and(or) preservation of methylmercury are greater in the Edisto system. The marked differences in net methylation potential observed between the wetland and in-stream settings suggest the hypothesis that methylmercury transport from zones of production (wetlands) to points of entry into the food chain (channels) may contribute to the observed differences in fish-tissue mercury concentrations between the two river systems.

Moderators of the relationship between masculinity and sexual prejudice in men: friendship, gender self-esteem, same-sex attraction, and religious fundamentalism.

PubMed

Mellinger, Christopher; Levant, Ronald F

2014-04-01

Masculinity has been found to predict the sexual prejudice of heterosexual men against gay men. The present study investigated the role of four variables as moderators of the relationships between two masculinity constructs (endorsement of traditional masculinity ideology and gender role conflict) and sexual prejudice in men. The hypothesized moderators were: direct and indirect friendships with gay men, gender self-esteem, acknowledged same-sex attraction, and religious fundamentalism. A total of 383 men completed 8 scales plus a demographic questionnaire. Direct friendship strengthened the positive relationship between masculinity ideology and sexual prejudice, contrary to hypothesis. This finding could mean that high masculinity ideology scores reduced the likelihood that a man with many gay friends would let go of his prejudice. Direct friendship did not moderate the relationship between gender role conflict and sexual prejudice nor did indirect friendship moderate either relationship; however, both forms of friendship predicted prejudice, as hypothesized. Gender self-esteem strengthened the positive relationships between both masculinity variables and sexual prejudice as hypothesized. Same-sex attraction weakened the relationship between gender role conflict and sexual prejudice as hypothesized, but contrary to hypothesis did not moderate the relationship between masculinity ideology and sexual prejudice. Religious fundamentalism predicted prejudice, but showed no significant moderation. The results were discussed in terms of limitations and suggestions for future research and application. In conclusion, this line of investigation appears promising and should be continued and the present findings can be utilized in anti-prejudice social marketing campaigns and in counseling.

What is the fundamental ion-specific series for anions and cations? Ion specificity in standard partial molar volumes of electrolytes and electrostriction in water and non-aqueous solvents.

PubMed

Mazzini, Virginia; Craig, Vincent S J

2017-10-01

The importance of electrolyte solutions cannot be overstated. Beyond the ionic strength of electrolyte solutions the specific nature of the ions present is vital in controlling a host of properties. Therefore ion specificity is fundamentally important in physical chemistry, engineering and biology. The observation that the strengths of the effect of ions often follows well established series suggests that a single predictive and quantitative description of specific-ion effects covering a wide range of systems is possible. Such a theory would revolutionise applications of physical chemistry from polymer precipitation to drug design. Current approaches to understanding specific-ion effects involve consideration of the ions themselves, the solvent and relevant interfaces and the interactions between them. Here we investigate the specific-ion effects trends of standard partial molar volumes and electrostrictive volumes of electrolytes in water and eleven non-aqueous solvents. We choose these measures as they relate to bulk properties at infinite dilution, therefore they are the simplest electrolyte systems. This is done to test the hypothesis that the ions alone exhibit a specific-ion effect series that is independent of the solvent and unrelated to surface properties. The specific-ion effects trends of standard partial molar volumes and normalised electrostrictive volumes examined in this work show a fundamental ion-specific series that is reproduced across the solvents, which is the Hofmeister series for anions and the reverse lyotropic series for cations, supporting the hypothesis. This outcome is important in demonstrating that ion specificity is observed at infinite dilution and demonstrates that the complexity observed in the manifestation of specific-ion effects in a very wide range of systems is due to perturbations of solvent, surfaces and concentration on the underlying fundamental series. This knowledge will guide a general understanding of specific-ion effects and assist in the development of a quantitative predictive theory of ion specificity.

Addressing the missing matter problem in galaxies through a new fundamental gravitational radius

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capozziello, S.; Jovanović, P.; Jovanović, V. Borka

We demonstrate that the existence of a Noether symmetry in f ( R ) theories of gravity gives rise to a further gravitational radius, besides the standard Schwarzschild one, determining the dynamics at galactic scales. By this feature, it is possible to explain the baryonic Tully-Fisher relation and the rotation curve of gas-rich galaxies without the dark matter hypothesis.

Effects of an Elementary Two Way Bilingual Spanish-English Immersion School Program on Junior High and High School Student Achievement

ERIC Educational Resources Information Center

Vega, Luis Diego

2014-01-01

This study explores the effects of a Two-Way Bilingual Immersion (TWBI) program on language majority and minority students. The fundamental hypothesis was that the process of receiving instruction in two languages (English and Spanish) throughout elementary school (i.e., attendance at a TWBI school) would help the native Spanish-speaking students…

40 years of neutrino physics

NASA Astrophysics Data System (ADS)

Reines, Frederick

Wolfgang Pauli and Enrico Fermi pioneered the hypothesis and characteristics of the weak interaction and the elementary particle called the neutrino. Since its discovery some forty years ago the neutrino has been shown to be a fundamental constituent of matter with a surprisingly rich, and in very many ways unexpected, set of characteristics ranging from basic roles in the generation of energy in the sun to supernovæ.

Using "Saccharomyces cerevisiae" to Test the Mutagenicity of Household Compounds: An Open Ended Hypothesis-Driven Teaching Lab

ERIC Educational Resources Information Center

Marshall, Pamela A.

2007-01-01

In our Fundamentals of Genetics lab, students perform a wide variety of labs to reinforce and extend the topics covered in lecture. I developed an active-learning lab to augment the lecture topic of mutagenesis. In this lab exercise, students determine if a compound they bring from home is a mutagen. Students are required to read extensive…

Prevention of the Post-traumatic Fibrotic Response in Joints

DTIC Science & Technology

2014-10-01

The American journal of forensic medicine and pathology . 1988; 9(4):310-2. 14 APPENDICES: An abstract submitted for the ORS conference...clinical problem of posttraumatic joint stiffness, a pathology that reduces the range of motion (ROM) of injured joints and contributes to the...development of osteoarthritis. The fundamental hypothesis that drives the current study is that pathological fibrotic response of injured joint tissues

Prevention of the Post-traumatic Fibrotic Response in Joints

DTIC Science & Technology

2014-10-01

an experimental model in mice. The American journal of forensic medicine and pathology . 1988; 9(4):310-2. 14 APPENDICES: An abstract...ongoing study addresses the critical clinical problem of posttraumatic joint stiffness, a pathology that reduces the range of motion (ROM) of injured...joints and contributes to the development of osteoarthritis. The fundamental hypothesis that drives the current study is that pathological fibrotic

Development of Mathematical Knowledge in Young Children: Attentional Skill and the Use of Inversion

ERIC Educational Resources Information Center

Watchorn, Rebecca P. D.; Bisanz, Jeffrey; Fast, Lisa; LeFevre, Jo-Anne; Skwarchuk, Sheri-Lynn; Smith-Chant, Brenda L.

2014-01-01

The principle of "inversion," that a + b - b "must" equal a, is a fundamental property of arithmetic, but many children fail to apply it in symbolic contexts through 10 years of age. We explore three hypotheses relating to the use of inversion that stem from a model proposed by Siegler and Araya (2005). Hypothesis 1 is that…

Simultaneous acquisition of multiple auditory-motor transformations in speech

PubMed Central

Rochet-Capellan, Amelie; Ostry, David J.

2011-01-01

The brain easily generates the movement that is needed in a given situation. Yet surprisingly, the results of experimental studies suggest that it is difficult to acquire more than one skill at a time. To do so, it has generally been necessary to link the required movement to arbitrary cues. In the present study, we show that speech motor learning provides an informative model for the acquisition of multiple sensorimotor skills. During training, subjects are required to repeat aloud individual words in random order while auditory feedback is altered in real-time in different ways for the different words. We find that subjects can quite readily and simultaneously modify their speech movements to correct for these different auditory transformations. This multiple learning occurs effortlessly without explicit cues and without any apparent awareness of the perturbation. The ability to simultaneously learn several different auditory-motor transformations is consistent with the idea that in speech motor learning, the brain acquires instance specific memories. The results support the hypothesis that speech motor learning is fundamentally local. PMID:21325534

From Shattered Assumptions to Weakened Worldviews: Trauma Symptoms Signal Anxiety Buffer Disruption.

PubMed

Edmondson, Donald; Chaudoir, Stephenie R; Mills, Mary Alice; Park, Crystal L; Holub, Julie; Bartkowiak, Jennifer M

2011-01-01

The fundamental assertion of worldview-based models of posttraumatic stress disorder is that trauma symptoms result when traumatic experiences cannot be readily assimilated into previously held worldviews. In two studies, we test the anxiety buffer disruption hypothesis, which states that trauma symptoms result from the disruption of normal death anxiety-buffering functions of worldview. In Study 1, participants with trauma symptoms greater than the cutoff for PTSD evinced greater death-thought accessibility than those with sub-clinical or negligible symptoms after a reminder of death. In Study 2, participants with clinically significant trauma symptoms showed no evidence of worldview defense though death-thoughts were accessible. These results support the anxiety buffer disruption hypothesis, and suggest an entirely new approach to experimental PTSD research.

Mirror neurons, birdsong, and human language: a hypothesis.

PubMed

Levy, Florence

2011-01-01

THE MIRROR SYSTEM HYPOTHESIS AND INVESTIGATIONS OF BIRDSONG ARE REVIEWED IN RELATION TO THE SIGNIFICANCE FOR THE DEVELOPMENT OF HUMAN SYMBOLIC AND LANGUAGE CAPACITY, IN TERMS OF THREE FUNDAMENTAL FORMS OF COGNITIVE REFERENCE: iconic, indexical, and symbolic. Mirror systems are initially iconic but can progress to indexical reference when produced without the need for concurrent stimuli. Developmental stages in birdsong are also explored with reference to juvenile subsong vs complex stereotyped adult syllables, as an analogy with human language development. While birdsong remains at an indexical reference stage, human language benefits from the capacity for symbolic reference. During a pre-linguistic "babbling" stage, recognition of native phonemic categories is established, allowing further development of subsequent prefrontal and linguistic circuits for sequential language capacity.

Mirror Neurons, Birdsong, and Human Language: A Hypothesis

PubMed Central

Levy, Florence

2012-01-01

The mirror system hypothesis and investigations of birdsong are reviewed in relation to the significance for the development of human symbolic and language capacity, in terms of three fundamental forms of cognitive reference: iconic, indexical, and symbolic. Mirror systems are initially iconic but can progress to indexical reference when produced without the need for concurrent stimuli. Developmental stages in birdsong are also explored with reference to juvenile subsong vs complex stereotyped adult syllables, as an analogy with human language development. While birdsong remains at an indexical reference stage, human language benefits from the capacity for symbolic reference. During a pre-linguistic “babbling” stage, recognition of native phonemic categories is established, allowing further development of subsequent prefrontal and linguistic circuits for sequential language capacity. PMID:22287950

Ergodic theorem, ergodic theory, and statistical mechanics

PubMed Central

Moore, Calvin C.

2015-01-01

This perspective highlights the mean ergodic theorem established by John von Neumann and the pointwise ergodic theorem established by George Birkhoff, proofs of which were published nearly simultaneously in PNAS in 1931 and 1932. These theorems were of great significance both in mathematics and in statistical mechanics. In statistical mechanics they provided a key insight into a 60-y-old fundamental problem of the subject—namely, the rationale for the hypothesis that time averages can be set equal to phase averages. The evolution of this problem is traced from the origins of statistical mechanics and Boltzman's ergodic hypothesis to the Ehrenfests' quasi-ergodic hypothesis, and then to the ergodic theorems. We discuss communications between von Neumann and Birkhoff in the Fall of 1931 leading up to the publication of these papers and related issues of priority. These ergodic theorems initiated a new field of mathematical-research called ergodic theory that has thrived ever since, and we discuss some of recent developments in ergodic theory that are relevant for statistical mechanics. PMID:25691697

Ancient fossil specimens of extinct species are genetically more distant to an outgroup than extant sister species are

PubMed Central

Huang, Shi

2009-01-01

There exists a remarkable correlation between genetic distance as measured by protein or DNA dissimilarity and time of species divergence as inferred from fossil records. This observation has provoked the molecular clock hypothesis. However, data inconsistent with the hypothesis have steadily accumulated in recent years from studies of extant organisms. Here the published DNA and protein sequences from ancient fossil specimens were examined to see if they would support the molecular clock hypothesis. The hypothesis predicts that ancient specimens cannot be genetically more distant to an outgroup than extant sister species are. Also, two distinct ancient specimens cannot be genetically more distant than their extant sister species are. The findings here do not conform to these predictions. Neanderthals are more distant to chimpanzees and gorillas than modern humans are. Dinosaurs are more distant to frogs than extant birds are. Mastodons are more distant to opossums than other placental mammals are. The genetic distance between dinosaurs and mastodons is greater than that between extant birds and mammals. Therefore, while the molecular clock hypothesis is consistent with some data from extant organisms, it has yet to find support from ancient fossils. Far more damaging to the hypothesis than data from extant organisms, which merely question the constancy of mutation rate, the study of ancient fossil organisms here challenges for the first time the fundamental premise of modern evolution theory that genetic distances had always increased with time in the past history of life on Earth. PMID:18600632

Bacterial Overgrowth and Irritable Bowel Syndrome: Unifying Hypothesis or a Spurious Consequence of Proton Pump Inhibitors?

PubMed Central

Spiegel, Brennan M.R.; Chey, William D.; Chang, Lin

2010-01-01

Some studies indicate that small intestinal bacterial overgrowth (SIBO), as measured by hydrogen breath tests (HBT), is more prevalent in patients with irritable bowel syndrome (IBS) vs. matched controls without IBS. Although the data are conflicting, this observation has led to the hypothesis that SIBO may be a primary cause of IBS. Yet, it remains unclear whether SIBO is truly fundamental to the pathophysiology of IBS, or is instead a mere epiphenomenon or bystander of something else altogether. We hypothesize that SIBO might be a byproduct of the disproportionate use of proton pump inhibitors (PPIs) in IBS, as follows: (1) IBS patients are more likely than controls to receive PPI therapy; (2) PPI therapy may promote varying forms of SIBO by eliminating gastric acid; and (3) existing studies linking SIBO to IBS have not adjusted for or excluded the use of PPI therapy. When linked together, these premises form the basis for a simple and testable hypothesis: the relationship between SIBO and IBS may be confounded by PPIs. Our article explores these premises, lays out the argument supporting this “PPI hypothesis,” discusses potential implications, and outlines next steps to further investigate this possibility. PMID:19086951

Physical mechanism or evolutionary trade-off? Factors dictating the relationship between metabolic rate and ambient temperature in carabid beetles.

PubMed

Gudowska, Agnieszka; Schramm, Bartosz W; Czarnoleski, Marcin; Kozłowski, Jan; Bauchinger, Ulf

2017-08-01

The tight association between ambient temperature (T) and metabolic rate (MR) is a common occurrence in ectotherms, but the determinants of this association are not fully understood. This study examined whether the relationship between MR and T is the same among individuals, as predicted by the Universal Temperature Dependence hypothesis, or whether this relationship differs between them. We used flow-through respirometry to measure standard MR and to determine gas exchange patterns for 111 individuals of three Carabidae species which differ in size (Abax ovalis, Carabus linnei and C. coriaceus), exposed to four different temperatures (ten individuals of each species measured at 6, 11, 16 and 21°C). We found a significant interaction between ln body mass and the inverse of temperature, indicating that in a given species, the effect of temperature on MR was weaker in larger individuals than in smaller individuals. Overall, this finding shows that the thermal dependence of MR is not body mass invariant. We observed three types of gas exchange patterns among beetles: discontinuous, cyclic and continuous. Additionally, the appearance of these patterns was associated with MR and T. Evolution in diverse terrestrial environments could affect diverse ventilation patterns, which accommodate changes in metabolism in response to temperature variation. In conclusion, explaining the variance in metabolism only through fundamental physical laws of thermodynamics, as predicted by the Universal Temperature Dependence hypothesis, appears to oversimplify the complexity of nature, ignoring evolutionary trade-offs that should be taken into account in the temperature - metabolism relationship. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fundamentals in Biostatistics for Research in Pediatric Dentistry: Part I - Basic Concepts.

PubMed

Garrocho-Rangel, J A; Ruiz-Rodríguez, M S; Pozos-Guillén, A J

The purpose of this report was to provide the reader with some basic concepts in order to better understand the significance and reliability of the results of any article on Pediatric Dentistry. Currently, Pediatric Dentists need the best evidence available in the literature on which to base their diagnoses and treatment decisions for the children's oral care. Basic understanding of Biostatistics plays an important role during the entire Evidence-Based Dentistry (EBD) process. This report describes Biostatistics fundamentals in order to introduce the basic concepts used in statistics, such as summary measures, estimation, hypothesis testing, effect size, level of significance, p value, confidence intervals, etc., which are available to Pediatric Dentists interested in reading or designing original clinical or epidemiological studies.

Different processes lead to similar patterns: a test of codivergence and the role of sea level and climate changes in shaping a southern temperate freshwater assemblage

PubMed Central

2011-01-01

Background Understanding how freshwater assemblages have been formed and maintained is a fundamental goal in evolutionary and ecological disciplines. Here we use a historical approach to test the hypothesis of codivergence in three clades of the Chilean freshwater species assemblage. Molecular studies of freshwater crabs (Aegla: Aeglidae: Anomura) and catfish (Trichomycterus arealatus: Trichomycteridae: Teleostei) exhibited similar levels of genetic divergences of mitochondrial lineages between species of crabs and phylogroups of the catfish, suggesting a shared evolutionary history among the three clades in this species assemblage. Results A phylogeny was constructed for Trichomycterus areolatus under the following best-fit molecular models of evolution GTR + I + R, HKY + I, and HKY for cytochrome b, growth hormone, and rag 1 respectively. A GTR + I + R model provided the best fit for both 28S and mitochondrial loci and was used to construct both Aegla phylogenies. Three different diversification models were observed and the three groups arose during different time periods, from 2.25 to 5.05 million years ago (Ma). Cladogenesis within Trichomycterus areolatus was initiated roughly 2.25 Ma (Late Pliocene - Early Pleistocene) some 1.7 - 2.8 million years after the basal divergences observed in both Aegla clades. These results reject the hypothesis of codivergence. Conclusions The similar genetic distances between terminal sister-lineages observed in these select taxa from the freshwater Chilean species assemblage were formed by different processes occurring over the last ~5.0 Ma. Dramatic changes in historic sea levels documented in the region appear to have independently shaped the evolutionary history of each group. Our study illustrates the important role that history plays in shaping a species assemblage and argues against assuming similar patterns equal a shared evolutionary history. PMID:22118288

Predicting nitrogen loading with land-cover composition: how can watershed size affect model performance?

PubMed

Zhang, Tao; Yang, Xiaojun

2013-01-01

Watershed-wide land-cover proportions can be used to predict the in-stream non-point source pollutant loadings through regression modeling. However, the model performance can vary greatly across different study sites and among various watersheds. Existing literature has shown that this type of regression modeling tends to perform better for large watersheds than for small ones, and that such a performance variation has been largely linked with different interwatershed landscape heterogeneity levels. The purpose of this study is to further examine the previously mentioned empirical observation based on a set of watersheds in the northern part of Georgia (USA) to explore the underlying causes of the variation in model performance. Through the combined use of the neutral landscape modeling approach and a spatially explicit nutrient loading model, we tested whether the regression model performance variation over the watershed groups ranging in size is due to the different watershed landscape heterogeneity levels. We adopted three neutral landscape modeling criteria that were tied with different similarity levels in watershed landscape properties and used the nutrient loading model to estimate the nitrogen loads for these neutral watersheds. Then we compared the regression model performance for the real and neutral landscape scenarios, respectively. We found that watershed size can affect the regression model performance both directly and indirectly. Along with the indirect effect through interwatershed heterogeneity, watershed size can directly affect the model performance over the watersheds varying in size. We also found that the regression model performance can be more significantly affected by other physiographic properties shaping nitrogen delivery effectiveness than the watershed land-cover heterogeneity. This study contrasts with many existing studies because it goes beyond hypothesis formulation based on empirical observations and into hypothesis testing to explore the fundamental mechanism.

Modeling the Development of Goal-Specificity in Mirror Neurons.

PubMed

Thill, Serge; Svensson, Henrik; Ziemke, Tom

2011-12-01

Neurophysiological studies have shown that parietal mirror neurons encode not only actions but also the goal of these actions. Although some mirror neurons will fire whenever a certain action is perceived (goal-independently), most will only fire if the motion is perceived as part of an action with a specific goal. This result is important for the action-understanding hypothesis as it provides a potential neurological basis for such a cognitive ability. It is also relevant for the design of artificial cognitive systems, in particular robotic systems that rely on computational models of the mirror system in their interaction with other agents. Yet, to date, no computational model has explicitly addressed the mechanisms that give rise to both goal-specific and goal-independent parietal mirror neurons. In the present paper, we present a computational model based on a self-organizing map, which receives artificial inputs representing information about both the observed or executed actions and the context in which they were executed. We show that the map develops a biologically plausible organization in which goal-specific mirror neurons emerge. We further show that the fundamental cause for both the appearance and the number of goal-specific neurons can be found in geometric relationships between the different inputs to the map. The results are important to the action-understanding hypothesis as they provide a mechanism for the emergence of goal-specific parietal mirror neurons and lead to a number of predictions: (1) Learning of new goals may mostly reassign existing goal-specific neurons rather than recruit new ones; (2) input differences between executed and observed actions can explain observed corresponding differences in the number of goal-specific neurons; and (3) the percentage of goal-specific neurons may differ between motion primitives.

Social learning of vocal structure in a nonhuman primate?

PubMed Central

2011-01-01

Background Non-human primate communication is thought to be fundamentally different from human speech, mainly due to vast differences in vocal control. The lack of these abilities in non-human primates is especially striking if compared to some marine mammals and bird species, which has generated somewhat of an evolutionary conundrum. What are the biological roots and underlying evolutionary pressures of the human ability to voluntarily control sound production and learn the vocal utterances of others? One hypothesis is that this capacity has evolved gradually in humans from an ancestral stage that resembled the vocal behavior of modern primates. Support for this has come from studies that have documented limited vocal flexibility and convergence in different primate species, typically in calls used during social interactions. The mechanisms underlying these patterns, however, are currently unknown. Specifically, it has been difficult to rule out explanations based on genetic relatedness, suggesting that such vocal flexibility may not be the result of social learning. Results To address this point, we compared the degree of acoustic similarity of contact calls in free-ranging Campbell's monkeys as a function of their social bonds and genetic relatedness. We calculated three different indices to compare the similarities between the calls' frequency contours, the duration of grooming interactions and the microsatellite-based genetic relatedness between partners. We found a significantly positive relation between bond strength and acoustic similarity that was independent of genetic relatedness. Conclusion Genetic factors determine the general species-specific call repertoire of a primate species, while social factors can influence the fine structure of some the call types. The finding is in line with the more general hypothesis that human speech has evolved gradually from earlier primate-like vocal communication. PMID:22177339

Macrophytes shape trophic niche variation among generalist fishes.

PubMed

Vejříková, Ivana; Eloranta, Antti P; Vejřík, Lukáš; Šmejkal, Marek; Čech, Martin; Sajdlová, Zuzana; Frouzová, Jaroslava; Kiljunen, Mikko; Peterka, Jiří

2017-01-01

Generalist species commonly have a fundamental role in ecosystems as they can integrate spatially distinct habitats and food-web compartments, as well as control the composition, abundance and behavior of organisms at different trophic levels. Generalist populations typically consist of specialized individuals, but the potential for and hence degree of individual niche variation can be largely determined by habitat complexity. We compared individual niche variation within three generalist fishes between two comparable lakes in the Czech Republic differing in macrophyte cover, i.e. macrophyte-rich Milada and macrophyte-poor Most. We tested the hypothesis that large individual niche variation among generalist fishes is facilitated by the presence of macrophytes, which provides niches and predation shelter for fish and their prey items. Based on results from stable nitrogen (δ15N) and carbon (δ13C) isotopic mixing models, perch (Perca fluviatilis L.) and rudd (Scardinius erythrophthalmus (L.)) showed larger individual variation (i.e., variance) in trophic position in Milada as compared to Most, whereas no significant between-lake differences were observed for roach (Rutilus rutilus (L.)). Contrary to our hypothesis, all the three species showed significantly lower individual variation in the relative reliance on littoral food resources in Milada than in Most. Rudd relied significantly more whereas perch and roach relied less on littoral food resources in Milada than in Most, likely due to prevalent herbivory by rudd and prevalent zooplanktivory by perch and roach in the macrophyte-rich Milada as compared to macrophyte-poor Most. Our study demonstrates how the succession of macrophyte vegetation, via its effects on the physical and biological complexity of the littoral zone and on the availability of small prey fish and zooplankton, can strongly influence individual niche variation among generalist fishes with different ontogenetic trajectories, and hence the overall food-web structures in lake ecosystems.

Science Fairs and Observational Science: A Case History from Earth Orbit

NASA Technical Reports Server (NTRS)

Lowman, Paul D., Jr.; Smith, David E. (Technical Monitor)

2002-01-01

Having judged dozens of science fairs over the years, I am repeatedly disturbed by the ground rules under which students must prepare their entries. They are almost invariably required to follow the "scientific method," involving formulating a hypothesis, a test of the hypothesis, and then a project in which this test is carried out. As a research scientist for over 40 years, I consider this approach to science fairs fundamentally unsound. It is not only too restrictive, but actually avoids the most important (and difficult) part of scientific research: recognizing a scientific problem in the first place. A well-known example is one of the problems that, by his own account, stimulated Einstein's theory of special relativity: the obvious fact that when an electric current is induced in a conductor by a magnetic field , it makes no difference whether the field or the conductor is actually (so to speak) moving. There is in other words no such thing as absolute motion. Physics was transformed by Einstein's recognition of a problem. Most competent scientists can solve problems after they have been recognized and a hypothesis properly formulated, but the ability to find problems in the first Place is much rarer. Getting down to specifics, the "scientific method" under which almost all students must operate is actually the experimental method, involving controlled variables, one of which, ideally, is changed at a time. However, there is another type of science that can be called observational science. As it happens, almost all the space research I have carried out since 1959 has been this type, not experimental science.

Perceptions of variability in facial emotion influence beliefs about the stability of psychological characteristics.

PubMed

Weisbuch, Max; Grunberg, Rebecca L; Slepian, Michael L; Ambady, Nalini

2016-10-01

Beliefs about the malleability versus stability of traits (incremental vs. entity lay theories) have a profound impact on social cognition and self-regulation, shaping phenomena that range from the fundamental attribution error and group-based stereotyping to academic motivation and achievement. Less is known about the causes than the effects of these lay theories, and in the current work the authors examine the perception of facial emotion as a causal influence on lay theories. Specifically, they hypothesized that (a) within-person variability in facial emotion signals within-person variability in traits and (b) social environments replete with within-person variability in facial emotion encourage perceivers to endorse incremental lay theories. Consistent with Hypothesis 1, Study 1 participants were more likely to attribute dynamic (vs. stable) traits to a person who exhibited several different facial emotions than to a person who exhibited a single facial emotion across multiple images. Hypothesis 2 suggests that social environments support incremental lay theories to the extent that they include many people who exhibit within-person variability in facial emotion. Consistent with Hypothesis 2, participants in Studies 2-4 were more likely to endorse incremental theories of personality, intelligence, and morality after exposure to multiple individuals exhibiting within-person variability in facial emotion than after exposure to multiple individuals exhibiting a single emotion several times. Perceptions of within-person variability in facial emotion-rather than perceptions of simple diversity in facial emotion-were responsible for these effects. Discussion focuses on how social ecologies shape lay theories. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Decoding Size Distribution Patterns in Marine and Transitional Water Phytoplankton: From Community to Species Level

PubMed Central

Roselli, Leonilde; Basset, Alberto

2015-01-01

Understanding the mechanisms of phytoplankton community assembly is a fundamental issue of aquatic ecology. Here, we use field data from transitional (e.g. coastal lagoons) and coastal water environments to decode patterns of phytoplankton size distribution into organization and adaptive mechanisms. Transitional waters are characterized by higher resource availability and shallower well-mixed water column than coastal marine environments. Differences in physico-chemical regime between the two environments have been hypothesized to exert contrasting selective pressures on phytoplankton cell morphology (size and shape). We tested the hypothesis focusing on resource availability (nutrients and light) and mixed layer depth as ecological axes that define ecological niches of phytoplankton. We report fundamental differences in size distributions of marine and freshwater diatoms, with transitional water phytoplankton significantly smaller and with higher surface to volume ratio than marine species. Here, we hypothesize that mixing condition affecting size-dependent sinking may drive phytoplankton size and shape distributions. The interplay between shallow mixed layer depth and frequent and complete mixing of transitional waters may likely increase the competitive advantage of small phytoplankton limiting large cell fitness. The nutrient regime appears to explain the size distribution within both marine and transitional water environments, while it seem does not explain the pattern observed across the two environments. In addition, difference in light availability across the two environments appear do not explain the occurrence of asymmetric size distribution at each hierarchical level. We hypothesize that such competitive equilibria and adaptive strategies in resource exploitation may drive by organism’s behavior which exploring patch resources in transitional and marine phytoplankton communities. PMID:25974052

The Oxygen Equilibrium of Mammalian Hemoglobin

PubMed Central

Roughton, F. J. W.

1965-01-01

The three chief physicochemical theories of the oxygen-hemoglobin equilibrium in vogue 40 years ago still influence current thought on the problem. Although the Hill theory lost its fundamental basis some 40 years ago, the famous empiric equation to which it gave rise is still much used, as a useful phenomenological expression, only involving two disposable constants. The Haldane theory, of which a difference in aggregation of oxygenated and deoxygenated hemoglobin was a fundamental feature, lay for many years dormant but has recently had an astonishing reawakening through the work on lamprey hemoglobin, which clearly reveals such differences in aggregation. Lamprey hemoglobin might thus be called a "Haldane type" hemoglobin. Adair's four-stage intermediate compound theory still seems applicable in the case of hemoglobins such as those of sheep, whose tetramer molecules do not tend to dissociate into dimers, and which might therefore be called "Adair type" hemoglobins. Horse and human hemoglobins appear to reveal both "Haldane" and "Adair" behaviour. The effects of pH, temperature, and protein concentration on the oxygen-equilibrium of sheep hemoglobin are summarised, and it is shown that, although the equilibrium curves are often isomorphous over their middle range, intensive work at the top and bottom of the curves reveals considerable differences in the relative effects of these factors on the several equilibrium constants of Adair's four intermediate equations. In the last section an account is given of preliminary experimental attempts to interpret the oxygen- and carbon monoxide—equilibrium curves of whole human blood, under physiological conditions in terms of the Adair intermediate compound hypothesis. PMID:5859923

New Approach to Quantum Entanglement According to the Theory of the Harmonicity of the Field of Light

NASA Astrophysics Data System (ADS)

Raftopoulos, Dionysios G.

Werner Heisenberg's well known requirement that Physical Science ought to occupy itself solely with entities that are both observable and measurable, is almost universally accepted. Starting from the above thesis and accepting Albert Einstein's second fundamental hypothesis, as stated in his historical article "On the Electrodynamics of moving Bodies", we are led to the conclusion that the kinematics of a material point, as measured and described by a localized real-life Observer, always refers not to its present position but rather to the one it occupied at a previous moment in time, which we call Conjugate Position, or Retarded Position according to Richard Feynman. From the experimenter's point of view, only the Conjugate position is important. Thus, the moving entity is observed and measured at a position that is different to the one it occupies now, a conclusion eerily evocative of the "shadows" paradigm in Plato's Cave Allegory. This, i.e. the kinematics of the Conjugate Position, is analytically described by the "Theory of Harmonicity of the Field of Light". Having selected the Projective Space as its Geometrical space of choice, an important conclusion of this theory is that, for a localized Observer, a linearly moving object is possible to appear simultaneously at two different positions and, consequently, at two different states in the Observer's Perceptible Space. This conclusion leads to the formulation of at least two fundamental theorems as well as to a plethora of corollaries all in accordance with the notions of contemporary Quantum Mechanics. A new form of the Unified Field of Light is presented.

Designing Computer Agents With Facial Personality To Improve Human-Machine Collaboration

DTIC Science & Technology

2006-05-25

Francis Galton is credited with recognizing the fundamental lexical hypothesis which states that you can identify “the more conspicuous aspects of the...available to describe more important traits. Galton (1884) also surmised that although there are a thousand subtly unique words used to describe character...inconsistent. A hallmark of intelligence , what potentially separates human beings from earlier life forms, is the ability to think about future consequences

Restoring NAD(+) Levels with NAD(+) Intermediates, the Second Law of Thermodynamics and Aging Delay.

PubMed

Poljsak, Borut; Milisav, Irina

2018-04-26

The hypothesis regarding the role of increased nicotinamide adenine dinucleotide (NAD+) levels with reference to the fundamental concepts of ageing and entropy is presented. Considering the second law of thermodynamics, NAD+ seems the appropriate candidate for reversing many aging-associated pathologies. NAD+ is presented as an essential compound that enables organisms to stay highly organized and well-maintained, with a lower entropy state.

Application of logistic analysis to the history of physics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

LePoire, D. J.; Environmental Assessment

2005-05-01

Recently, two analyses have tried to put technological progress in a larger context. One interpretation hypothesizes that technological progress is likely to continue at increasingly higher rates of change. Another interpretation, which includes data from the beginning of the universe to the present, suggests that the universe is approaching a transition point in a logistic development of complexity. This logistic development is similar to the way ideas or products diffuse in a population, i.e., the rate of discovery in a field of knowledge is proportional to the amount discovered and the amount to be discovered. To test a part ofmore » this hypothesis, a leading indicator field (fundamental physics) was identified and the events in the history of this field were analyzed. Twelve subfields were identified and grouped into six stages. Each stage seemed to demonstrate a logistic-like development. By analyzing both the median time of development and the characteristic time of development of these stages, the overall development of this one field was found to suggest logistic development. These data seem to indicate that development in fundamental physics is slowing down, with at least one subfield beyond string physics yet to be developed. The data tend to support the hypothesis that a knowledge field can develop logistically.« less

Cognitive framing in action.

PubMed

Huhn, John M; Potts, Cory Adam; Rosenbaum, David A

2016-06-01

Cognitive framing effects have been widely reported in higher-level decision-making and have been ascribed to rules of thumb for quick thinking. No such demonstrations have been reported for physical action, as far as we know, but they would be expected if cognition for physical action is fundamentally similar to cognition for higher-level decision-making. To test for such effects, we asked participants to reach for a horizontally-oriented pipe to move it from one height to another while turning the pipe 180° to bring one end (the "business end") to a target on the left or right. From a physical perspective, participants could have always rotated the pipe in the same angular direction no matter which end was the business end; a given participant could have always turned the pipe clockwise or counter-clockwise. Instead, our participants turned the business end counter-clockwise for left targets and clockwise for right targets. Thus, the way the identical physical task was framed altered the way it was performed. This finding is consistent with the hypothesis that cognition for physical action is fundamentally similar to cognition for higher-level decision-making. A tantalizing possibility is that higher-level decision heuristics have roots in the control of physical action, a hypothesis that accords with embodied views of cognition. Copyright © 2016 Elsevier B.V. All rights reserved.

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

ERIC Educational Resources Information Center

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.…

Personality psychology: lexical approaches, assessment methods, and trait concepts reveal only half of the story--why it is time for a paradigm shift.

PubMed

Uher, Jana

2013-03-01

This article develops a comprehensive philosophy-of-science for personality psychology that goes far beyond the scope of the lexical approaches, assessment methods, and trait concepts that currently prevail. One of the field's most important guiding scientific assumptions, the lexical hypothesis, is analysed from meta-theoretical viewpoints to reveal that it explicitly describes two sets of phenomena that must be clearly differentiated: 1) lexical repertoires and the representations that they encode and 2) the kinds of phenomena that are represented. Thus far, personality psychologists largely explored only the former, but have seriously neglected studying the latter. Meta-theoretical analyses of these different kinds of phenomena and their distinct natures, commonalities, differences, and interrelations reveal that personality psychology's focus on lexical approaches, assessment methods, and trait concepts entails a) erroneous meta-theoretical assumptions about what the phenomena being studied actually are, and thus how they can be analysed and interpreted, b) that contemporary personality psychology is largely based on everyday psychological knowledge, and c) a fundamental circularity in the scientific explanations used in trait psychology. These findings seriously challenge the widespread assumptions about the causal and universal status of the phenomena described by prominent personality models. The current state of knowledge about the lexical hypothesis is reviewed, and implications for personality psychology are discussed. Ten desiderata for future research are outlined to overcome the current paradigmatic fixations that are substantially hampering intellectual innovation and progress in the field.

Map LineUps: Effects of spatial structure on graphical inference.

PubMed

Beecham, Roger; Dykes, Jason; Meulemans, Wouter; Slingsby, Aidan; Turkay, Cagatay; Wood, Jo

2017-01-01

Fundamental to the effective use of visualization as an analytic and descriptive tool is the assurance that presenting data visually provides the capability of making inferences from what we see. This paper explores two related approaches to quantifying the confidence we may have in making visual inferences from mapped geospatial data. We adapt Wickham et al.'s 'Visual Line-up' method as a direct analogy with Null Hypothesis Significance Testing (NHST) and propose a new approach for generating more credible spatial null hypotheses. Rather than using as a spatial null hypothesis the unrealistic assumption of complete spatial randomness, we propose spatially autocorrelated simulations as alternative nulls. We conduct a set of crowdsourced experiments (n=361) to determine the just noticeable difference (JND) between pairs of choropleth maps of geographic units controlling for spatial autocorrelation (Moran's I statistic) and geometric configuration (variance in spatial unit area). Results indicate that people's abilities to perceive differences in spatial autocorrelation vary with baseline autocorrelation structure and the geometric configuration of geographic units. These results allow us, for the first time, to construct a visual equivalent of statistical power for geospatial data. Our JND results add to those provided in recent years by Klippel et al. (2011), Harrison et al. (2014) and Kay & Heer (2015) for correlation visualization. Importantly, they provide an empirical basis for an improved construction of visual line-ups for maps and the development of theory to inform geospatial tests of graphical inference.

Development and behavior of wild infant-juvenile East Bornean orangutans (Pongo pygmaeus morio) in Danum Valley.

PubMed

Mendonça, Renata S; Kanamori, Tomoko; Kuze, Noko; Hayashi, Misato; Bernard, Henry; Matsuzawa, Tetsuro

2017-01-01

Orangutans have a long period of immaturity and the longest inter-birth interval (IBI) of all mammals, which can be explained by their solitary life style, preventing the mother from rearing two offspring simultaneously (solitary life hypothesis) [corrected]. We collected data on mother-offspring dyads living in a primary lowland forest in Danum Valley, East Borneo in an effort to examine the developmental and behavioral patterns of the subspecies Pongo pygmaeus morio. We analyzed developmental changes in mother-offspring distance, contact, and activity budgets in orangutans ranging from 1 to 7 years of age. The results indicated decreased resting and playing with increasing age, whereas feeding, traveling and social play all increased significantly. Mothers' feeding and traveling time were good predictors of their offspring's feeding and traveling activities. Mother-offspring contact lasted longer in resting contexts; contact during traveling was almost non-existent after 4 years of age. Comparisons with previously published data on the Sumatran species Pongo abelli revealed no fundamental differences in these behavioral measures. However, a shorter association time with the mother after behavioral independence is documented for this East Bornean population in comparison to Sumatran populations. These results are best explained by the solitary life hypothesis, in agreement with previous studies. We suggest that environmental constraints in Bornean forests, as well as a lower population density, should be considered when interpreting the differences between Sumatran and Bornean orangutans in both the period of association with mother and the IBI.

Neurobiological constraints on behavioral models of motivation.

PubMed

Nader, K; Bechara, A; van der Kooy, D

1997-01-01

The application of neurobiological tools to behavioral questions has produced a number of working models of the mechanisms mediating the rewarding and aversive properties of stimuli. The authors review and compare three models that differ in the nature and number of the processes identified. The dopamine hypothesis, a single system model, posits that the neurotransmitter dopamine plays a fundamental role in mediating the rewarding properties of all classes of stimuli. In contrast, both nondeprived/deprived and saliency attribution models claim that separate systems make independent contributions to reward. The former identifies the psychological boundary defined by the two systems as being between states of nondeprivation (e.g. food sated) and deprivation (e.g. hunger). The latter identifies a boundary between liking and wanting systems. Neurobiological dissociations provide tests of and explanatory power for behavioral theories of goal-directed behavior.

Studying Biological Responses to Global Change in Atmospheric Oxygen

PubMed Central

Powell, Frank L.

2010-01-01

A popular book recently hypothesized that change in atmospheric oxygen over geological time is the most important physical factor in the evolution of many fundamental characteristics of modern terrestrial animals. This hypothesis is generated primarily using fossil data but the present paper considers how modern experimental biology can be used to test it. Comparative physiology and experimental evolution clearly show that changes in atmospheric O2 over the ages had the potential to drive evolution, assuming the physiological O2-sensitivity of animals today is similar to the past. Established methods, such as phylogenetically independent contrasts, as well new approaches, such as adding environmental history to phylogenetic analyses or modeling interactions between environmental stresses and biological responses with different rate constants, may be useful for testing (disproving) hypotheses about biological adaptations to changes in atmospheric O2. PMID:20385257

On Psychic Determinism.

PubMed

Brown, Robin Gordon

2017-06-01

A confusion persists in the psychoanalytic literature regarding the concept of psychic determinism. Two authors are cited in whose works the concept is identified as foundational to psychoanalysis, in the one case as a "fundamental hypothesis" (Charles Brenner) and in the other as an "underlying presupposition" or assumption (Linda A.W. Brakel). Both claims are based on a conflation of the concept Freud had in mind with a philosophical doctrine going by the same name but meaning something quite different. The philosophical doctrine has no place in psychoanalysis at all, and Freud's concept does not play a foundational role there. In a second section a restricted concept of psychic determinism is critically examined. A third section deals with the impact of that restricted concept on clinical theory and contemporary controversies about clinical practice. Finally, some possible reasons for this confusion are suggested.

Frameworks for Proof-of-Concept Clinical Trials of Interventions That Target Fundamental Aging Processes

PubMed Central

Justice, Jamie; Miller, Jordan D.; Newman, John C.; Hashmi, Shahrukh K.; Halter, Jeffrey; Austad, Steve N.; Barzilai, Nir

2016-01-01

Therapies targeted at fundamental processes of aging may hold great promise for enhancing the health of a wide population by delaying or preventing a range of age-related diseases and conditions—a concept dubbed the “geroscience hypothesis.” Early, proof-of-concept clinical trials will be a key step in the translation of therapies emerging from model organism and preclinical studies into clinical practice. This article summarizes the outcomes of an international meeting partly funded through the NIH R24 Geroscience Network, whose purpose was to generate concepts and frameworks for early, proof-of-concept clinical trials for therapeutic interventions that target fundamental processes of aging. The goals of proof-of-concept trials include generating preliminary signals of efficacy in an aging-related disease or outcome that will reduce the risk of conducting larger trials, contributing data and biological samples to support larger-scale research by strategic networks, and furthering a dialogue with regulatory agencies on appropriate registration indications. We describe three frameworks for proof-of-concept trials that target age-related chronic diseases, geriatric syndromes, or resilience to stressors. We propose strategic infrastructure and shared resources that could accelerate development of therapies that target fundamental aging processes. PMID:27535966

Apes have culture but may not know that they do

PubMed Central

Gruber, Thibaud; Zuberbühler, Klaus; Clément, Fabrice; van Schaik, Carel

2015-01-01

There is good evidence that some ape behaviors can be transmitted socially and that this can lead to group-specific traditions. However, many consider animal traditions, including those in great apes, to be fundamentally different from human cultures, largely because of lack of evidence for cumulative processes and normative conformity, but perhaps also because current research on ape culture is usually restricted to behavioral comparisons. Here, we propose to analyze ape culture not only at the surface behavioral level but also at the underlying cognitive level. To this end, we integrate empirical findings in apes with theoretical frameworks developed in developmental psychology regarding the representation of tools and the development of metarepresentational abilities, to characterize the differences between ape and human cultures at the cognitive level. Current data are consistent with the notion of apes possessing mental representations of tools that can be accessed through re-representations: apes may reorganize their knowledge of tools in the form of categories or functional schemes. However, we find no evidence for metarepresentations of cultural knowledge: apes may not understand that they or others hold beliefs about their cultures. The resulting Jourdain Hypothesis, based on Molière’s character, argues that apes express their cultures without knowing that they are cultural beings because of cognitive limitations in their ability to represent knowledge, a determining feature of modern human cultures, allowing representing and modifying the current norms of the group. Differences in metarepresentational processes may thus explain fundamental differences between human and other animals’ cultures, notably limitations in cumulative behavior and normative conformity. Future empirical work should focus on how animals mentally represent their cultural knowledge to conclusively determine the ways by which humans are unique in their cultural behavior. PMID:25705199

Generalized Knudsen Number for Oscillatory Flows Generated by MEMS and NEMS Resonators

NASA Astrophysics Data System (ADS)

Ekinci, Kamil; Kara, Vural; Yakhot, Victor

2017-11-01

We have explored the scaling behavior of oscillatory flows that are generated by the oscillations of MEMS and NEMS resonators in a gas. If the gas is gradually rarefied, the Navier-Stokes equations begin to fail and a kinetic description of the flow becomes more appropriate. The failure of the Navier-Stokes equations can be thought to take place via two different physical mechanisms: either the continuum hypothesis breaks down as a result of a finite size effect; or local equilibrium is violated due to the high rate of strain. By independently tuning the relevant linear dimensions and the frequencies of the MEMS and NEMS resonators, we experimentally observe these two different physical mechanisms. All the experimental data, however, can be collapsed using a single dimensionless scaling parameter that combines the linear dimension and the frequency of each resonator. This proposed Knudsen number for oscillatory flows is rooted in a fundamental symmetry principle, namely Galilean invariance. We acknowledge support from US NSF through Grant No. CBET-1604075.

Alternative Watson-Crick Synthetic Genetic Systems.

PubMed

Benner, Steven A; Karalkar, Nilesh B; Hoshika, Shuichi; Laos, Roberto; Shaw, Ryan W; Matsuura, Mariko; Fajardo, Diego; Moussatche, Patricia

2016-11-01

In its "grand challenge" format in chemistry, "synthesis" as an activity sets out a goal that is substantially beyond current theoretical and technological capabilities. In pursuit of this goal, scientists are forced across uncharted territory, where they must answer unscripted questions and solve unscripted problems, creating new theories and new technologies in ways that would not be created by hypothesis-directed research. Thus, synthesis drives discovery and paradigm changes in ways that analysis cannot. Described here are the products that have arisen so far through the pursuit of one grand challenge in synthetic biology: Recreate the genetics, catalysis, evolution, and adaptation that we value in life, but using genetic and catalytic biopolymers different from those that have been delivered to us by natural history on Earth. The outcomes in technology include new diagnostic tools that have helped personalize the care of hundreds of thousands of patients worldwide. In science, the effort has generated a fundamentally different view of DNA, RNA, and how they work. Copyright © 2016 Cold Spring Harbor Laboratory Press; all rights reserved.

Effects of verbal and nonverbal interference on spatial and object visual working memory.

PubMed

Postle, Bradley R; Desposito, Mark; Corkin, Suzanne

2005-03-01

We tested the hypothesis that a verbal coding mechanism is necessarily engaged by object, but not spatial, visual working memory tasks. We employed a dual-task procedure that paired n-back working memory tasks with domain-specific distractor trials inserted into each interstimulus interval of the n-back tasks. In two experiments, object n-back performance demonstrated greater sensitivity to verbal distraction, whereas spatial n-back performance demonstrated greater sensitivity to motion distraction. Visual object and spatial working memory may differ fundamentally in that the mnemonic representation of featural characteristics of objects incorporates a verbal (perhaps semantic) code, whereas the mnemonic representation of the location of objects does not. Thus, the processes supporting working memory for these two types of information may differ in more ways than those dictated by the "what/where" organization of the visual system, a fact more easily reconciled with a component process than a memory systems account of working memory function.

Fundamental(ist) attribution error: Protestants are dispositionally focused.

PubMed

Li, Yexin Jessica; Johnson, Kathryn A; Cohen, Adam B; Williams, Melissa J; Knowles, Eric D; Chen, Zhansheng

2012-02-01

Attribution theory has long enjoyed a prominent role in social psychological research, yet religious influences on attribution have not been well studied. We theorized and tested the hypothesis that Protestants would endorse internal attributions to a greater extent than would Catholics, because Protestantism focuses on the inward condition of the soul. In Study 1, Protestants made more internal, but not external, attributions than did Catholics. This effect survived controlling for Protestant work ethic, need for structure, and intrinsic and extrinsic religiosity. Study 2 showed that the Protestant-Catholic difference in internal attributions was significantly mediated by Protestants' greater belief in a soul. In Study 3, priming religion increased belief in a soul for Protestants but not for Catholics. Finally, Study 4 found that experimentally strengthening belief in a soul increased dispositional attributions among Protestants but did not change situational attributions. These studies expand the understanding of cultural differences in attributions by demonstrating a distinct effect of religion on dispositional attributions.

Effects of verbal and nonverbal interference on spatial and object visual working memory

PubMed Central

POSTLE, BRADLEY R.; D’ESPOSITO, MARK; CORKIN, SUZANNE

2005-01-01

We tested the hypothesis that a verbal coding mechanism is necessarily engaged by object, but not spatial, visual working memory tasks. We employed a dual-task procedure that paired n-back working memory tasks with domain-specific distractor trials inserted into each interstimulus interval of the n-back tasks. In two experiments, object n-back performance demonstrated greater sensitivity to verbal distraction, whereas spatial n-back performance demonstrated greater sensitivity to motion distraction. Visual object and spatial working memory may differ fundamentally in that the mnemonic representation of featural characteristics of objects incorporates a verbal (perhaps semantic) code, whereas the mnemonic representation of the location of objects does not. Thus, the processes supporting working memory for these two types of information may differ in more ways than those dictated by the “what/where” organization of the visual system, a fact more easily reconciled with a component process than a memory systems account of working memory function. PMID:16028575

To punish or repair? Evolutionary psychology and lay intuitions about modern criminal justice.

PubMed

Petersen, Michael Bang; Sell, Aaron; Tooby, John; Cosmides, Leda

2012-11-01

We propose that intuitions about modern mass-level criminal justice emerge from evolved mechanisms designed to operate in ancestral small-scale societies. By hypothesis, individuals confronted with a crime compute two distinct psychological magnitudes: one that reflects the crime's seriousness and another that reflects the criminal's long-term value as an associate. These magnitudes are computed based on different sets of cues and are fed into motivational mechanisms regulating different aspects of sanctioning. The seriousness variable regulates how much to react (e.g., how severely we want to punish); the variable indexing the criminal's association value regulates the more fundamental decision of how to react (i.e., whether we want to punish or repair). Using experimental designs embedded in surveys, we validate this theory across several types of crime and two countries. The evidence augments past research and suggests that the human mind contains dedicated psychological mechanisms for restoring social relationships following acts of exploitation.

To punish or repair? Evolutionary psychology and lay intuitions about modern criminal justice

PubMed Central

Petersen, Michael Bang; Sell, Aaron; Tooby, John; Cosmides, Leda

2013-01-01

We propose that intuitions about modern mass-level criminal justice emerge from evolved mechanisms designed to operate in ancestral small-scale societies. By hypothesis, individuals confronted with a crime compute two distinct psychological magnitudes: one that reflects the crime’s seriousness and another that reflects the criminal’s long-term value as an associate. These magnitudes are computed based on different sets of cues and are fed into motivational mechanisms regulating different aspects of sanctioning. The seriousness variable regulates how much to react (e.g., how severely we want to punish); the variable indexing the criminal’s association value regulates the more fundamental decision of how to react (i.e., whether we want to punish or repair). Using experimental designs embedded in surveys, we validate this theory across several types of crime and two countries. The evidence augments past research and suggests that the human mind contains dedicated psychological mechanisms for restoring social relationships following acts of exploitation. PMID:23412662

Distinguishing between the partial-mapping preparation hypothesis and the failure-to-engage hypothesis of residual switch costs.

PubMed

Lindsen, Job P; de Jong, Ritske

2010-10-01

Lien, Ruthruff, Remington, & Johnston (2005) reported residual switch cost differences between stimulus-response (S-R) pairs and proposed the partial-mapping preparation (PMP) hypothesis, which states that advance preparation will typically be limited to a subset of S-R pairs because of structural capacity limitations, to account for these differences. Alternatively, the failure-to-engage (FTE) hypothesis does not allow for differences in probability of advance preparation between S-R pairs within a set; it accounts for residual switch cost differences by assuming that benefits of advance preparation may differ between S-R pairs. Three Experiments were designed to test between these hypotheses. No capacity limitations of the type assumed by the PMP hypothesis were found for many participants in Experiment 1. In Experiments 2 and 3, no evidence was found for the dependency of residual switch cost differences between S-R pairs on response-stimulus interval that is predicted by the PMP hypothesis. Mixture-model analysis of reaction times distributions in Experiment 3 provided strong support for the FTE hypothesis over the PMP hypothesis. Simulation studies with a computational implementation of the FTE hypothesis showed that it is able to account in great detail for the results of the present study. Together, these results provide strong evidence against the PMP hypothesis and support the FTE hypothesis that advance preparation probabilistically fails or succeeds at the level of the task set. (PsycINFO Database Record (c) 2010 APA, all rights reserved).

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

PubMed

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

2013-03-01

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

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

PubMed Central

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

2013-01-01

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

Body size distribution of the dinosaurs.

PubMed

O'Gorman, Eoin J; Hone, David W E

2012-01-01

The distribution of species body size is critically important for determining resource use within a group or clade. It is widely known that non-avian dinosaurs were the largest creatures to roam the Earth. There is, however, little understanding of how maximum species body size was distributed among the dinosaurs. Do they share a similar distribution to modern day vertebrate groups in spite of their large size, or did they exhibit fundamentally different distributions due to unique evolutionary pressures and adaptations? Here, we address this question by comparing the distribution of maximum species body size for dinosaurs to an extensive set of extant and extinct vertebrate groups. We also examine the body size distribution of dinosaurs by various sub-groups, time periods and formations. We find that dinosaurs exhibit a strong skew towards larger species, in direct contrast to modern day vertebrates. This pattern is not solely an artefact of bias in the fossil record, as demonstrated by contrasting distributions in two major extinct groups and supports the hypothesis that dinosaurs exhibited a fundamentally different life history strategy to other terrestrial vertebrates. A disparity in the size distribution of the herbivorous Ornithischia and Sauropodomorpha and the largely carnivorous Theropoda suggests that this pattern may have been a product of a divergence in evolutionary strategies: herbivorous dinosaurs rapidly evolved large size to escape predation by carnivores and maximise digestive efficiency; carnivores had sufficient resources among juvenile dinosaurs and non-dinosaurian prey to achieve optimal success at smaller body size.

Body Size Distribution of the Dinosaurs

PubMed Central

O’Gorman, Eoin J.; Hone, David W. E.

2012-01-01

The distribution of species body size is critically important for determining resource use within a group or clade. It is widely known that non-avian dinosaurs were the largest creatures to roam the Earth. There is, however, little understanding of how maximum species body size was distributed among the dinosaurs. Do they share a similar distribution to modern day vertebrate groups in spite of their large size, or did they exhibit fundamentally different distributions due to unique evolutionary pressures and adaptations? Here, we address this question by comparing the distribution of maximum species body size for dinosaurs to an extensive set of extant and extinct vertebrate groups. We also examine the body size distribution of dinosaurs by various sub-groups, time periods and formations. We find that dinosaurs exhibit a strong skew towards larger species, in direct contrast to modern day vertebrates. This pattern is not solely an artefact of bias in the fossil record, as demonstrated by contrasting distributions in two major extinct groups and supports the hypothesis that dinosaurs exhibited a fundamentally different life history strategy to other terrestrial vertebrates. A disparity in the size distribution of the herbivorous Ornithischia and Sauropodomorpha and the largely carnivorous Theropoda suggests that this pattern may have been a product of a divergence in evolutionary strategies: herbivorous dinosaurs rapidly evolved large size to escape predation by carnivores and maximise digestive efficiency; carnivores had sufficient resources among juvenile dinosaurs and non-dinosaurian prey to achieve optimal success at smaller body size. PMID:23284818

Initial cash/asset ratio and asset prices: an experimental study.

PubMed

Caginalp, G; Porter, D; Smith, V

1998-01-20

A series of experiments, in which nine participants trade an asset over 15 periods, test the hypothesis that an initial imbalance of asset/cash will influence the trading price over an extended time. Participants know at the outset that the asset or "stock" pays a single dividend with fixed expectation value at the end of the 15th period. In experiments with a greater total value of cash at the start, the mean prices during the trading periods are higher, compared with those with greater amount of asset, with a high degree of statistical significance. The difference is most significant at the outset and gradually tapers near the end of the experiment. The results are very surprising from a rational expectations and classical game theory perspective, because the possession of a large amount of cash does not lead to a simple motivation for a trader to bid excessively on a financial instrument. The gradual erosion of the difference toward the end of trading, however, suggests that fundamental value is approached belatedly, offering some consolation to the rational expectations theory. It also suggests that there is a time scale on which an evolution toward fundamental value occurs. The experimental results are qualitatively compatible with the price dynamics predicted by a system of differential equations based on asset flow. The results have broad implications for the marketing of securities, particularly initial and secondary public offerings, government bonds, etc., where excess supply has been conjectured to suppress prices.

Initial cash/asset ratio and asset prices: An experimental study

PubMed Central

Caginalp, Gunduz; Porter, David; Smith, Vernon

1998-01-01

A series of experiments, in which nine participants trade an asset over 15 periods, test the hypothesis that an initial imbalance of asset/cash will influence the trading price over an extended time. Participants know at the outset that the asset or “stock” pays a single dividend with fixed expectation value at the end of the 15th period. In experiments with a greater total value of cash at the start, the mean prices during the trading periods are higher, compared with those with greater amount of asset, with a high degree of statistical significance. The difference is most significant at the outset and gradually tapers near the end of the experiment. The results are very surprising from a rational expectations and classical game theory perspective, because the possession of a large amount of cash does not lead to a simple motivation for a trader to bid excessively on a financial instrument. The gradual erosion of the difference toward the end of trading, however, suggests that fundamental value is approached belatedly, offering some consolation to the rational expectations theory. It also suggests that there is a time scale on which an evolution toward fundamental value occurs. The experimental results are qualitatively compatible with the price dynamics predicted by a system of differential equations based on asset flow. The results have broad implications for the marketing of securities, particularly initial and secondary public offerings, government bonds, etc., where excess supply has been conjectured to suppress prices. PMID:11038619

Visual Field Map Clusters in Macaque Extrastriate Visual Cortex

PubMed Central

Kolster, Hauke; Mandeville, Joseph B.; Arsenault, John T.; Ekstrom, Leeland B.; Wald, Lawrence L.; Vanduffel, Wim

2009-01-01

The macaque visual cortex contains more than 30 different functional visual areas, yet surprisingly little is known about the underlying organizational principles that structure its components into a complete ‘visual’ unit. A recent model of visual cortical organization in humans suggests that visual field maps are organized as clusters. Clusters minimize axonal connections between individual field maps that represent common visual percepts, with different clusters thought to carry out different functions. Experimental support for this hypothesis, however, is lacking in macaques, leaving open the question of whether it is unique to humans or a more general model for primate vision. Here we show, using high-resolution BOLD fMRI data in the awake monkey at 7 Tesla, that area MT/V5 and its neighbors are organized as a cluster with a common foveal representation and a circular eccentricity map. This novel view on the functional topography of area MT/V5 and satellites indicates that field map clusters are evolutionarily preserved and may be a fundamental organizational principle of the old world primate visual cortex. PMID:19474330

Pathogen prevalence predicts human cross-cultural variability in individualism/collectivism.

PubMed

Fincher, Corey L; Thornhill, Randy; Murray, Damian R; Schaller, Mark

2008-06-07

Pathogenic diseases impose selection pressures on the social behaviour of host populations. In humans (Homo sapiens), many psychological phenomena appear to serve an antipathogen defence function. One broad implication is the existence of cross-cultural differences in human cognition and behaviour contingent upon the relative presence of pathogens in the local ecology. We focus specifically on one fundamental cultural variable: differences in individualistic versus collectivist values. We suggest that specific behavioural manifestations of collectivism (e.g. ethnocentrism, conformity) can inhibit the transmission of pathogens; and so we hypothesize that collectivism (compared with individualism) will more often characterize cultures in regions that have historically had higher prevalence of pathogens. Drawing on epidemiological data and the findings of worldwide cross-national surveys of individualism/collectivism, our results support this hypothesis: the regional prevalence of pathogens has a strong positive correlation with cultural indicators of collectivism and a strong negative correlation with individualism. The correlations remain significant even when controlling for potential confounding variables. These results help to explain the origin of a paradigmatic cross-cultural difference, and reveal previously undocumented consequences of pathogenic diseases on the variable nature of human societies.

From Shattered Assumptions to Weakened Worldviews: Trauma Symptoms Signal Anxiety Buffer Disruption

PubMed Central

Edmondson, Donald; Chaudoir, Stephenie R.; Mills, Mary Alice; Park, Crystal L.; Holub, Julie; Bartkowiak, Jennifer M.

2013-01-01

The fundamental assertion of worldview-based models of posttraumatic stress disorder is that trauma symptoms result when traumatic experiences cannot be readily assimilated into previously held worldviews. In two studies, we test the anxiety buffer disruption hypothesis, which states that trauma symptoms result from the disruption of normal death anxiety-buffering functions of worldview. In Study 1, participants with trauma symptoms greater than the cutoff for PTSD evinced greater death-thought accessibility than those with sub-clinical or negligible symptoms after a reminder of death. In Study 2, participants with clinically significant trauma symptoms showed no evidence of worldview defense though death-thoughts were accessible. These results support the anxiety buffer disruption hypothesis, and suggest an entirely new approach to experimental PTSD research. PMID:24077677

The efficacy of musical emotions provoked by Mozart's music for the reconciliation of cognitive dissonance.

PubMed

Masataka, Nobuo; Perlovsky, Leonid

2012-01-01

Debates on the origin and function of music have a long history. While some scientists argue that music itself plays no adaptive role in human evolution, others suggest that music clearly has an evolutionary role, and point to music's universality. A recent hypothesis suggested that a fundamental function of music has been to help mitigating cognitive dissonance, which is a discomfort caused by holding conflicting cognitions simultaneously. It usually leads to devaluation of conflicting knowledge. Here we provide experimental confirmation of this hypothesis using a classical paradigm known to create cognitive dissonance. Results of our experiment reveal that the exposure to Mozart's music exerted a strongly positive influence upon the performance of young children and served as basis by which they were enabled to reconcile the cognitive dissonance.

Suppressive mechanisms in visual motion processing: From perception to intelligence.

PubMed

Tadin, Duje

2015-10-01

Perception operates on an immense amount of incoming information that greatly exceeds the brain's processing capacity. Because of this fundamental limitation, the ability to suppress irrelevant information is a key determinant of perceptual efficiency. Here, I will review a series of studies investigating suppressive mechanisms in visual motion processing, namely perceptual suppression of large, background-like motions. These spatial suppression mechanisms are adaptive, operating only when sensory inputs are sufficiently robust to guarantee visibility. Converging correlational and causal evidence links these behavioral results with inhibitory center-surround mechanisms, namely those in cortical area MT. Spatial suppression is abnormally weak in several special populations, including the elderly and individuals with schizophrenia-a deficit that is evidenced by better-than-normal direction discriminations of large moving stimuli. Theoretical work shows that this abnormal weakening of spatial suppression should result in motion segregation deficits, but direct behavioral support of this hypothesis is lacking. Finally, I will argue that the ability to suppress information is a fundamental neural process that applies not only to perception but also to cognition in general. Supporting this argument, I will discuss recent research that shows individual differences in spatial suppression of motion signals strongly predict individual variations in IQ scores. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Stress, anxiety and depression in heart disease patients: A major challenge for cardiac rehabilitation.

PubMed

Chauvet-Gelinier, Jean-Christophe; Bonin, Bernard

2017-01-01

Cardiovascular events and emotional disorders share a common epidemiology, thus suggesting fundamental pathways linking these different diseases. Growing evidence in the literature highlights the influence of psychological determinants in somatic diseases. A patient's socio-economic aspects, personality traits, health behavior and even biological pathways may contribute to the course of cardiovascular disease. Cardiac events often occur suddenly and the episode can be traumatic for people not prepared for such an event. In this review of the literature, the authors tackle the question of psychobiological mechanisms of stress, in a pathophysiological approach to fundamental pathways linking the brain to the heart. Various psychological, biological and genetic arguments are presented in support of the hypothesis that various etiological mechanisms may be involved. The authors finally deal with biological and psychological strategies in a context of cardiovascular disease. Indeed, in this context, cardiac rehabilitation, with its global approach, seems to be a good time to diagnose emotional disorders like anxiety and depression, and to help people to cope with stressful events. In this field, cardiac rehabilitation seems to be a crucial step in order to improve patients' outcomes, by helping them to understand the influence of psychobiological risk factors, and to build strategies in order to manage daily stress. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

The hippocampus facilitates integration within a symbolic field.

PubMed

Cornelius, John Thor

2017-10-01

This paper attempts to elaborate a fundamental brain mechanism involved in the creation and maintenance of symbolic fields of thought. It will integrate theories of psychic spaces as explored by Donald Winnicott and Wilfred Bion with the neuroscientific examinations of those with bilateral hippocampal injury to show how evidence from both disciplines sheds important light on this aspect of mind. Possibly originating as a way of maintaining an oriented, first person psychic map, this capacity allows individuals a dynamic narrative access to a realm of layered elements and their connections. If the proposed hypothesis is correct, the hippocampus facilitates the integration of this symbolic field of mind, where narrative forms of thinking, creativity, memory, and dreaming are intertwined. Without the hippocampus, there is an inability to engage many typical forms of thought itself. Also, noting the ways these individuals are not impaired supports theories about other faculties of mind, providing insight into their possible roles within human thought. The evidence of different systems working in conjunction with the symbolic field provides tantalizing clues about these fundamental mechanisms of brain and mind that are normally seamlessly integrated, and hints at future areas of clinical and laboratory research, both within neuroscience and psychoanalysis. © 2017 The Authors. The International Journal of Psychoanalysis published by John Wiley & Sons Ltd on behalf of Institute of Psychoanalysis.

A "theory of relativity" for cognitive elasticity of time and modality dimensions supporting constant working memory capacity: involvement of harmonics among ultradian clocks?

PubMed

Glassman, R B

2000-02-01

1. The capacity of working memory (WM) for about 7+/-2 ("the magical number") serially organized simple verbal items may represent a fundamental constant of cognition. Indeed, there is the same capacity for sense of familiarity of a number of recently encountered places, observed in radial maze performance both of lab rats and of humans. 2. Moreover, both species show a peculiar capacity for retaining WM of place over delays. The literature also describes paradoxes of extended time duration in certain human verbal recall tasks. Certain bird species have comparable capacity for delayed recall of about 4 to 8 food caches in a laboratory room. 3. In addition to these paradoxes of the time dimension with WM (still sometimes called "short-term" memory) there are another set of paradoxes of dimensionality for human judgment of magnitudes, noted by Miller in his classic 1956 paper on "the magical number." We are able to reliably refer magnitudes to a rating scale of up to about seven divisions. Remarkably, that finding is largely independent of perceptual modality or even of the extent of a linear interval selected within any given modality. 4. These paradoxes suggest that "the magical number 7+/2" depends on fundamental properties of mammalian brains. 5. This paper theorizes that WM numerosity is conserved as a fundamental constant, by means of elasticity of cognitive dimensionality, including the temporal pace of arrival of significant items of cognitive information. 6. A conjectural neural code for WM item-capacity is proposed here, which extends the hypothetical principle of binding-by-synchrony. The hypothesis is that several coactive frequencies of brain electrical rhythms each mark a WM item. 7. If, indeed, WM does involve a brain wave frequency code (perhaps within the gamma frequency range that has often been suggested with the binding hypothesis) mathematical considerations suggest additional relevance of harmonic relationships. That is, if copresent sinusoids bear harmony-like ratios and are confined within a single octave, then they have fast temporal properties, while avoiding spurious difference rhythms. Therefore, if the present hypothesis is valid, it implies a natural limit on parallel processing of separate items in organismic brains. 8. Similar logic of periodic signals may hold for slower ultradian rhythms, including hypothetical ones that contribute to time-tagging and fresh sense of familiarity of a day's event memories. Similar logic may also hold for spatial periodic functions across brain tissue that, hypothetically, represent cognitive information. Thus, harmonic transitions among temporal and spatial periodic functions are a possible vehicle for the cognitive dimensional elasticity that conserves WM capacity. 9. Supporting roles are proposed of (a) basal ganglia, as a high-capacity cache for traces of recent experience temporarily suspended from active task-relevant processing and (b) of hippocampus as a phase and interval comparator for oscillating signals, whose spatiotemporal dynamics are topologically equivalent to a toroidal grid.

On contact problems of elasticity theory

NASA Technical Reports Server (NTRS)

Kalandiya, A. I.

1986-01-01

Certain contact problems are reviewed in the two-dimensional theory of elasticity when round bodies touch without friction along most of the boundary and, therefore, Herz' hypothesis on the smallness of the contact area cannot be used. Fundamental equations were derived coinciding externally with the equation in the theory of a finite-span wing with unkown parameter. These equations are solved using Multhopp's well-known technique, and numerical calculations are performed in specific examples.

Debates—Hypothesis testing in hydrology: Pursuing certainty versus pursuing uberty

NASA Astrophysics Data System (ADS)

Baker, Victor R.

2017-03-01

Modern hydrology places nearly all its emphasis on science-as-knowledge, the hypotheses of which are increasingly expressed as physical models, whose predictions are tested by correspondence to quantitative data sets. Though arguably appropriate for applications of theory to engineering and applied science, the associated emphases on truth and degrees of certainty are not optimal for the productive and creative processes that facilitate the fundamental advancement of science as a process of discovery. The latter requires an investigative approach, where the goal is uberty, a kind of fruitfulness of inquiry, in which the abductive mode of inference adds to the much more commonly acknowledged modes of deduction and induction. The resulting world-directed approach to hydrology provides a valuable complement to the prevailing hypothesis- (theory-) directed paradigm.