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Sample records for selection function naturally

  1. When natural selection gives gene function the cold shoulder.

    Science.gov (United States)

    Cutter, Asher D; Jovelin, Richard

    2015-11-01

    It is tempting to invoke organismal selection as perpetually optimizing the function of any given gene. However, natural selection can drive genic functional change without improvement of biochemical activity, even to the extinction of gene activity. Detrimental mutations can creep in owing to linkage with other selectively favored loci. Selection can promote functional degradation, irrespective of genetic drift, when adaptation occurs by loss of gene function. Even stabilizing selection on a trait can lead to divergence of the underlying molecular constituents. Selfish genetic elements can also proliferate independent of any functional benefits to the host genome. Here we review the logic and evidence for these diverse processes acting in genome evolution. This collection of distinct evolutionary phenomena - while operating through easily understandable mechanisms - all contribute to the seemingly counterintuitive notion that maintenance or improvement of a gene's biochemical function sometimes do not determine its evolutionary fate. © 2015 WILEY Periodicals, Inc.

  2. Estimating the residential demand function for natural gas in Seoul with correction for sample selection bias

    International Nuclear Information System (INIS)

    Yoo, Seung-Hoon; Lim, Hea-Jin; Kwak, Seung-Jun

    2009-01-01

    Over the last twenty years, the consumption of natural gas in Korea has increased dramatically. This increase has mainly resulted from the rise of consumption in the residential sector. The main objective of the study is to estimate households' demand function for natural gas by applying a sample selection model using data from a survey of households in Seoul. The results show that there exists a selection bias in the sample and that failure to correct for sample selection bias distorts the mean estimate, of the demand for natural gas, downward by 48.1%. In addition, according to the estimation results, the size of the house, the dummy variable for dwelling in an apartment, the dummy variable for having a bed in an inner room, and the household's income all have positive relationships with the demand for natural gas. On the other hand, the size of the family and the price of gas negatively contribute to the demand for natural gas. (author)

  3. Allocating structure to function: the strong links between neuroplasticity and natural selection

    Directory of Open Access Journals (Sweden)

    Michael L Anderson

    2014-01-01

    Full Text Available A central question in brain evolution is how species-typical behaviors, and the neural function-structure mappings supporting them, can be acquired and inherited. Advocates of brain modularity, in its different incarnations across scientific subfields, argue that natural selection must target domain-dedicated, separately modifiable neural subsystems, resulting in genetically-specified functional modules. In such modular systems, specification of neuron number and functional connectivity are necessarily linked. Mounting evidence, however, from allometric, developmental, comparative, systems-physiological, neuroimaging and neurological studies suggests that brain elements are used and reused in multiple functional systems. This variable allocation can be seen in short-term neuromodulation, in neuroplasticity over the lifespan and in response to damage. We argue that the same processes are evident in brain evolution. Natural selection must preserve behavioral functions that may co-locate in variable amounts with other functions. In genetics, the uses and problems of pleiotropy, the re-use of genes in multiple networks have been much discussed, but this issue has been sidestepped in neural systems by the invocation of modules. Here we highlight the interaction between evolutionary and developmental mechanisms to produce distributed and overlapping functional architectures in the brain. These adaptive mechanisms must be robust to perturbations that might disrupt critical information processing and action selection, but must also recognize useful new sources of information arising from internal genetic or environmental variability, when those appear. These contrasting properties of robustness and evolvability have been discussed for the basic organization of body plan and fundamental cell physiology. Here we extend them to the evolution and development, evo-devo, of brain structure.

  4. Reinventing Natural Selection

    Science.gov (United States)

    Geraedts, Caspar L.; Boersma, Kerst Th.

    2006-01-01

    Although many research studies report students' Lamarckian misconceptions, only a few studies present learning and teaching strategies that focus on the successful development of the concept of natural selection. The learning and teaching strategy for upper secondary students (aged 15-16) presented in this study conducted in The Netherlands is…

  5. Logic and Natural selection

    Czech Academy of Sciences Publication Activity Database

    Peregrin, Jaroslav

    2010-01-01

    Roč. 4, č. 2 (2010), s. 207-223 ISSN 1661-8297 R&D Projects: GA ČR(CZ) GAP401/10/1279 Institutional research plan: CEZ:AV0Z9009908 Keywords : logic * natural selection * modus potens * inferentialism Subject RIV: AA - Philosophy ; Religion

  6. Mitochondrial functions of THP-1 monocytes following the exposure to selected natural compounds.

    Science.gov (United States)

    Schultze, Nadin; Wanka, Heike; Zwicker, Paula; Lindequist, Ulrike; Haertel, Beate

    2017-02-15

    The immune system is an important target of various xenobiotics, which may lead to severe adverse effects including immunosuppression or inappropriate immunostimulation. Mitochondrial toxicity is one possibility by which xenobiotics exert their toxic effects in cells or organs. In this study, we investigated the impact of three natural compounds, cyclosporine A (CsA), deoxynivalenol (DON) and cannabidiol (CBD) on mitochondrial functions in the THP-1 monocytic cell line. The cells were exposed for 24h to two different concentrations (IC 10 and IC 50 determined by MTT) of each compound. The cells showed concentration-dependent elevated intracellular reactive oxygen species (iROS) and induction of apoptosis (except DON) in response to the three test compounds. Mitochondrial functions were characterized by using bioenergetics profiling experiments. In THP-1 monocytes, the IC 50 of CsA decreased basal and maximal respiration as well as ATP production with an impact on spare capacity indicating a mitochondrial dysfunction. Similar reaction patterns were observed following CBD exposure. The basal respiration level and ATP-production decreased in the THP-1 cells exposed to the IC 50 of DON with no major impact on mitochondrial function. In conclusion, impaired mitochondrial function was accompanied by elevated iROS and apoptosis level in a monocytic cell line exposed to CsA and CBD. Mitochondrial dysfunction may be one explanation for the cytotoxicity of CBD and CsA also in other in immune cells. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  7. Natural Selection and Morality

    Directory of Open Access Journals (Sweden)

    Alejandro Rosas

    2006-12-01

    Full Text Available Resumen:En este ensayo abordo los intentos, relativamente recientes, de dar una explicación de la moralidad como adaptación por selección natural. Mi exposición tiene una introducción y cuatro partes: en la primera explico en qué consiste la paradoja del altruismo biológico. En la segunda expongo la solución que apela a la selección de grupos, recientemente resurgida; la solución que presuntamente aplicó Charles Darwin cuando formuló sus reflexiones biológicas sobre la moralidad humana. En la tercera expongo la solución sociobiológica, que opta por negar que la selección natural pueda explicar directamente la moralidad humana. La moralidad se presenta más bien como opuesta a la naturaleza diseñada por selección natural. En la cuarta parte desarrollo brevemente una explicación de la moralidad como adaptación que beneficia a los individuos. No opone la moralidad a la naturaleza, ni apela a la selección de grupos. Se sirve de un mecanismo de selección que opera a través de preferencias en la interacción social.Abstract:In this essay, I address recent attempts to account for morality as an adaptation due to natural selection. After a brief introduction, my exposition has four sections. I first explain the paradox of biological altruism. Second, I explain the solution to the paradox in terms of group selection. This solution was presumably applied by Darwin himself as he discussed human morality, and it has experienced a recent revival, though it remains suspicious to most biologists. In the third section I offer a socio-biological solution that opts for denying that morality can be explained by any form of natural selection. Morality is opposed to human nature as designed by natural selection. In the fourth, I argue for an explanation in terms of individual selection. It does not oppose morality to nature, and does not need the workings of group selection; rather, it operates through the agents’ psychological preferences

  8. Natural selection promotes antigenic evolvability.

    Science.gov (United States)

    Graves, Christopher J; Ros, Vera I D; Stevenson, Brian; Sniegowski, Paul D; Brisson, Dustin

    2013-01-01

    The hypothesis that evolvability - the capacity to evolve by natural selection - is itself the object of natural selection is highly intriguing but remains controversial due in large part to a paucity of direct experimental evidence. The antigenic variation mechanisms of microbial pathogens provide an experimentally tractable system to test whether natural selection has favored mechanisms that increase evolvability. Many antigenic variation systems consist of paralogous unexpressed 'cassettes' that recombine into an expression site to rapidly alter the expressed protein. Importantly, the magnitude of antigenic change is a function of the genetic diversity among the unexpressed cassettes. Thus, evidence that selection favors among-cassette diversity is direct evidence that natural selection promotes antigenic evolvability. We used the Lyme disease bacterium, Borrelia burgdorferi, as a model to test the prediction that natural selection favors amino acid diversity among unexpressed vls cassettes and thereby promotes evolvability in a primary surface antigen, VlsE. The hypothesis that diversity among vls cassettes is favored by natural selection was supported in each B. burgdorferi strain analyzed using both classical (dN/dS ratios) and Bayesian population genetic analyses of genetic sequence data. This hypothesis was also supported by the conservation of highly mutable tandem-repeat structures across B. burgdorferi strains despite a near complete absence of sequence conservation. Diversification among vls cassettes due to natural selection and mutable repeat structures promotes long-term antigenic evolvability of VlsE. These findings provide a direct demonstration that molecular mechanisms that enhance evolvability of surface antigens are an evolutionary adaptation. The molecular evolutionary processes identified here can serve as a model for the evolution of antigenic evolvability in many pathogens which utilize similar strategies to establish chronic infections.

  9. Natural selection promotes antigenic evolvability.

    Directory of Open Access Journals (Sweden)

    Christopher J Graves

    Full Text Available The hypothesis that evolvability - the capacity to evolve by natural selection - is itself the object of natural selection is highly intriguing but remains controversial due in large part to a paucity of direct experimental evidence. The antigenic variation mechanisms of microbial pathogens provide an experimentally tractable system to test whether natural selection has favored mechanisms that increase evolvability. Many antigenic variation systems consist of paralogous unexpressed 'cassettes' that recombine into an expression site to rapidly alter the expressed protein. Importantly, the magnitude of antigenic change is a function of the genetic diversity among the unexpressed cassettes. Thus, evidence that selection favors among-cassette diversity is direct evidence that natural selection promotes antigenic evolvability. We used the Lyme disease bacterium, Borrelia burgdorferi, as a model to test the prediction that natural selection favors amino acid diversity among unexpressed vls cassettes and thereby promotes evolvability in a primary surface antigen, VlsE. The hypothesis that diversity among vls cassettes is favored by natural selection was supported in each B. burgdorferi strain analyzed using both classical (dN/dS ratios and Bayesian population genetic analyses of genetic sequence data. This hypothesis was also supported by the conservation of highly mutable tandem-repeat structures across B. burgdorferi strains despite a near complete absence of sequence conservation. Diversification among vls cassettes due to natural selection and mutable repeat structures promotes long-term antigenic evolvability of VlsE. These findings provide a direct demonstration that molecular mechanisms that enhance evolvability of surface antigens are an evolutionary adaptation. The molecular evolutionary processes identified here can serve as a model for the evolution of antigenic evolvability in many pathogens which utilize similar strategies to establish

  10. Molecular Signatures of Natural Selection

    DEFF Research Database (Denmark)

    Nielsen, Rasmus

    2005-01-01

    provide important functional information. This review provides a nonmathematical description of the issues involved in detecting selection from DNA sequences and SNP data and is intended for readers who are not familiar with population genetic theory. Particular attention is placed on issues relating......There is an increasing interest in detecting genes, or genomic regions, that have been targeted by natural selection. The interest stems from a basic desire to learn more about evolutionary processes in humans and other organisms, and from the realization that inferences regarding selection may...

  11. Modeling Natural Selection

    Science.gov (United States)

    Bogiages, Christopher A.; Lotter, Christine

    2011-01-01

    In their research, scientists generate, test, and modify scientific models. These models can be shared with others and demonstrate a scientist's understanding of how the natural world works. Similarly, students can generate and modify models to gain a better understanding of the content, process, and nature of science (Kenyon, Schwarz, and Hug…

  12. Natural selection promotes antigenic evolvability

    NARCIS (Netherlands)

    Graves, C.J.; Ros, V.I.D.; Stevenson, B.; Sniegowski, P.D.; Brisson, D.

    2013-01-01

    The hypothesis that evolvability - the capacity to evolve by natural selection - is itself the object of natural selection is highly intriguing but remains controversial due in large part to a paucity of direct experimental evidence. The antigenic variation mechanisms of microbial pathogens provide

  13. Natural Selection in the Great Apes.

    Science.gov (United States)

    Cagan, Alexander; Theunert, Christoph; Laayouni, Hafid; Santpere, Gabriel; Pybus, Marc; Casals, Ferran; Prüfer, Kay; Navarro, Arcadi; Marques-Bonet, Tomas; Bertranpetit, Jaume; Andrés, Aida M

    2016-12-01

    Natural selection is crucial for the adaptation of populations to their environments. Here, we present the first global study of natural selection in the Hominidae (humans and great apes) based on genome-wide information from population samples representing all extant species (including most subspecies). Combining several neutrality tests we create a multi-species map of signatures of natural selection covering all major types of natural selection. We find that the estimated efficiency of both purifying and positive selection varies between species and is significantly correlated with their long-term effective population size. Thus, even the modest differences in population size among the closely related Hominidae lineages have resulted in differences in their ability to remove deleterious alleles and to adapt to changing environments. Most signatures of balancing and positive selection are species-specific, with signatures of balancing selection more often being shared among species. We also identify loci with evidence of positive selection across several lineages. Notably, we detect signatures of positive selection in several genes related to brain function, anatomy, diet and immune processes. Our results contribute to a better understanding of human evolution by putting the evidence of natural selection in humans within its larger evolutionary context. The global map of natural selection in our closest living relatives is available as an interactive browser at http://tinyurl.com/nf8qmzh. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  14. Rhodium(II) metallopeptide catalyst design enables fine control in selective functionalization of natural SH3 domains.

    Science.gov (United States)

    Vohidov, Farrukh; Coughlin, Jane M; Ball, Zachary T

    2015-04-07

    Chemically modified proteins are increasingly important for use in fundamental biophysical studies, chemical biology, therapeutic protein development, and biomaterials. However, chemical methods typically produce heterogeneous labeling and cannot approach the exquisite selectivity of enzymatic reactions. While bioengineered methods are sometimes an option, selective reactions of natural proteins remain an unsolved problem. Here we show that rhodium(II) metallopeptides combine molecular recognition with promiscuous catalytic activity to allow covalent decoration of natural SH3 domains, depending on choice of catalyst but independent of the specific residue present. A metallopeptide catalyst succeeds in modifying a single SH3-containing kinase at endogenous concentrations in prostate cancer (PC-3) cell lysate. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Structural Complexity and Ecosystem Functions in a Natural Mixed Forest under a Single-Tree Selection Silviculture

    Directory of Open Access Journals (Sweden)

    Toshiya Yoshida

    2017-11-01

    Full Text Available The objective of forest management has become broader, and it is essential to harmonize timber production with conservation of the forest ecosystem. Selection cutting is recognized as a major alternative of clear-cutting, because it can maintain the complexity and heterogeneity of a natural forest; however, its long-term evaluations are limited. This study compared various attributes of stand structures, which are indicators of biodiversity and ecosystem carbon stock between managed and unmanaged blocks (12.6 ha area in total in a natural mixed forest in Hokkaido, the northernmost island of Japan. We found that 30 years’ implementation of single-tree selection did not affect the volume, size structure, species diversity nor spatial distribution of overstory trees in the managed stands. Also, the total carbon stock in the managed stands was almost equal to that of the unmanaged stands. In contrast, several structural attributes and indicator elements that are significant for biodiversity (such as large-diameter live trees, dead trees, cavities, epiphytic bryophytes, and some avian guilds showed marked decrease in the managed stands. We conclude that it is required to leave these structures and elements to some extent for deriving the merit of the management as an alternative silvicultural regime in the region.

  16. Comparing Patterns of Natural Selection Across Species Using Selective Signatures

    Energy Technology Data Exchange (ETDEWEB)

    Alm, Eric J.; Shapiro, B. Jesse; Alm, Eric J.

    2007-12-18

    Comparing gene expression profiles over many different conditions has led to insights that were not obvious from single experiments. In the same way, comparing patterns of natural selection across a set of ecologically distinct species may extend what can be learned from individual genome-wide surveys. Toward this end, we show how variation in protein evolutionary rates, after correcting for genome-wide effects such as mutation rate and demographic factors, can be used to estimate the level and types of natural selection acting on genes across different species. We identify unusually rapidly and slowly evolving genes, relative to empirically derived genome-wide and gene family-specific background rates for 744 core protein families in 30 gamma-proteobacterial species. We describe the pattern of fast or slow evolution across species as the 'selective signature' of a gene. Selective signatures represent a profile of selection across species that is predictive of gene function: pairs of genes with correlated selective signatures are more likely to share the same cellular function, and genes in the same pathway can evolve in concert. For example, glycolysis and phenylalanine metabolism genes evolve rapidly in Idiomarina loihiensis, mirroring an ecological shift in carbon source from sugars to amino acids. In a broader context, our results suggest that the genomic landscape is organized into functional modules even at the level of natural selection, and thus it may be easier than expected to understand the complex evolutionary pressures on a cell.

  17. Comparing Patterns of Natural Selection across Species Using Selective Signatures

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, Jesse; Alm, Eric J.

    2007-12-01

    Comparing gene expression profiles over many different conditions has led to insights that were not obvious from single experiments. In the same way, comparing patterns of natural selection across a set of ecologically distinct species may extend what can be learned from individual genome-wide surveys. Toward this end, we show how variation in protein evolutionary rates, after correcting for genome-wide effects such as mutation rate and demographic factors, can be used to estimate the level and types of natural selection acting on genes across different species. We identify unusually rapidly and slowly evolving genes, relative to empirically derived genome-wide and gene family-specific background rates for 744 core protein families in 30 c-proteobacterial species. We describe the pattern of fast or slow evolution across species as the"selective signature" of a gene. Selective signatures represent aprofile of selection across species that is predictive of gene function: pairs of genes with correlated selective signatures are more likely to share the same cellular function, and genes in the same pathway can evolve in concert. For example,glycolysis and phenylalanine metabolism genes evolve rapidly in Idiomarina loihiensis, mirroring an ecological shift in carbon source from sugars to amino acids. In a broader context, our results suggest that the genomic landscape is organized into functional modules even at the level of natural selection, and thus it may be easier than expected to understand the complex evolutionary pressures on a cell.

  18. Natural Selection in Large Populations

    Science.gov (United States)

    Desai, Michael

    2011-03-01

    I will discuss theoretical and experimental approaches to the evolutionary dynamics and population genetics of natural selection in large populations. In these populations, many mutations are often present simultaneously, and because recombination is limited, selection cannot act on them all independently. Rather, it can only affect whole combinations of mutations linked together on the same chromosome. Methods common in theoretical population genetics have been of limited utility in analyzing this coupling between the fates of different mutations. In the past few years it has become increasingly clear that this is a crucial gap in our understanding, as sequence data has begun to show that selection appears to act pervasively on many linked sites in a wide range of populations, including viruses, microbes, Drosophila, and humans. I will describe approaches that combine analytical tools drawn from statistical physics and dynamical systems with traditional methods in theoretical population genetics to address this problem, and describe how experiments in budding yeast can help us directly observe these evolutionary dynamics.

  19. Sleep researchers need to bring Darwin on board: elucidating functions of sleep via adaptedness and natural selection

    OpenAIRE

    Kavanau, Julian L.

    2004-01-01

    The development of neural multifunctionality – given brain regions carrying out more than one function – conferred great efficiency on brain function at early stages of evolution. This applied to animals that led relatively simple lives with few needs for long-term memories, such as many lower invertebrates – many molluscs, echinoderms, worms, etc. As more complex lifestyles and detailed focal vision evolved, needs for self-initiated and reflexive activities increased in frequency, and recogn...

  20. Selective capture of cesium and thallium from natural waters and simulated wastes with copper ferrocyanide functionalized mesoporous silica

    Energy Technology Data Exchange (ETDEWEB)

    Sangvanich, Thanapon [Biomedical Engineering, Oregon Health and Science University (OHSU) School of Medicine, Portland, OR 97239 (United States); Sukwarotwat, Vichaya; Wiacek, Robert J.; Grudzien, Rafal M.; Fryxell, Glen E.; Addleman, R. Shane; Timchalk, Charles [Pacific Northwest National Laboratory (PNNL), 902 Battelle Boulevard, Richland, WA 99352 (United States); Yantasee, Wassana, E-mail: yantasee@ohsu.edu [Biomedical Engineering, Oregon Health and Science University (OHSU) School of Medicine, Portland, OR 97239 (United States)

    2010-10-15

    Copper(II) ferrocyanide on mesoporous silica (FC-Cu-EDA-SAMMS{sup TM}) has been evaluated against iron(III) hexacyanoferrate(II) (insoluble Prussian Blue) for removing cesium (Cs{sup +}) and thallium (Tl{sup +}) from natural waters and simulated acidic and alkaline wastes. From pH 0.1-7.3, FC-Cu-EDA-SAMMS had greater affinities for Cs and Tl and was less affected by the solution pH, competing cations, and matrices. SAMMS also outperformed Prussian Blue in terms of adsorption capacities (e.g., 21.7 versus 2.6 mg Cs/g in acidic waste stimulant (pH 1.1), 28.3 versus 5.8 mg Tl/g in seawater), and rate (e.g., over 95 wt% of Cs was removed from seawater after 2 min with SAMMS, while only 75 wt% was removed with Prussian Blue). SAMMS also had higher stability (e.g., 2.5-13-fold less Fe dissolved from 2 to 24 h of contact time). In addition to environmental applications, SAMMS has great potential to be used as orally administered drug for limiting the absorption of radioactive Cs and toxic Tl in gastrointestinal tract.

  1. Phenotypic selection in natural populations: what limits directional selection?

    Science.gov (United States)

    Kingsolver, Joel G; Diamond, Sarah E

    2011-03-01

    Studies of phenotypic selection document directional selection in many natural populations. What factors reduce total directional selection and the cumulative evolutionary responses to selection? We combine two data sets for phenotypic selection, representing more than 4,600 distinct estimates of selection from 143 studies, to evaluate the potential roles of fitness trade-offs, indirect (correlated) selection, temporally varying selection, and stabilizing selection for reducing net directional selection and cumulative responses to selection. We detected little evidence that trade-offs among different fitness components reduced total directional selection in most study systems. Comparisons of selection gradients and selection differentials suggest that correlated selection frequently reduced total selection on size but not on other types of traits. The direction of selection on a trait often changes over time in many temporally replicated studies, but these fluctuations have limited impact in reducing cumulative directional selection in most study systems. Analyses of quadratic selection gradients indicated stabilizing selection on body size in at least some studies but provided little evidence that stabilizing selection is more common than disruptive selection for most traits or study systems. Our analyses provide little evidence that fitness trade-offs, correlated selection, or stabilizing selection strongly constrains the directional selection reported for most quantitative traits.

  2. Natural selection and animal personality

    NARCIS (Netherlands)

    Dingemanse, NJ; Reale, D

    2005-01-01

    Recent progress has been made on the study of personality in animals, both from a mechanistic and a functional perspective. While we start knowing more about the proximal mechanisms responsible for the consistent differences in behaviour between individuals in a population, little is known yet about

  3. Selective extraction of natural bitumen

    International Nuclear Information System (INIS)

    Starshov, M.; Starshov, I.

    1991-01-01

    The work performed in the field of natural bitumen extraction is aimed at maximum separation of organic phase. On treating bituminous rocks with solvents, the associated metals are extracted together with the organic phase and may further exert a negative effect on refining of natural bitumen. the authors propose a simplified two stage technique for the extraction of bitumen which enables to utilize V and Ni contained in the concentrate of the second stage extraction (Table). At the first stage, negative bitumen is extracted with the summary content of metals not exceeding 0.005%. This allows to avoid de metallization of native bitumen and subject it to treatment by catalytic cracking. during this stage gasoline and kerosene fractions, different oil distillates and condensates can be used as solvents. at the second stage, aromatic and halo id compounds bearing wastes and by-products, i.e. cheap and non deficient reagents, serve as solvents. The technology was tested under laboratory conditions using Tatar bituminous sands. It is also possible to use one solvent only, however, on condition that at first the oil product with the summary metal content below 0.005%, and then the remaining product is extracted. The proposed technology has proved so universal that it can be applied to refining any type of raw material to be found in the territory of the Tatar republic, using surface extraction complexes. (author). 9 refs., tab

  4. Population Genetics and Natural Selection in Rheumatic Disease.

    Science.gov (United States)

    Ramos, Paula S

    2017-08-01

    Human genetic diversity is the result of population genetic forces. This genetic variation influences disease risk and contributes to health disparities. Natural selection is an important influence on human genetic variation. Because immune and inflammatory function genes are enriched for signals of positive selection, the prevalence of rheumatic disease-risk alleles seen in different populations is partially the result of differing selective pressures (eg, due to pathogens). This review summarizes the genetic regions associated with susceptibility to different rheumatic diseases and concomitant evidence for natural selection, including known agents of selection exerting selective pressure in these regions. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. A Gambler's Model of Natural Selection.

    Science.gov (United States)

    Nolan, Michael J.; Ostrovsky, David S.

    1996-01-01

    Presents an activity that highlights the mechanism and power of natural selection. Allows students to think in terms of modeling a biological process and instills an appreciation for a mathematical approach to biological problems. (JRH)

  6. Selective functionalization of carbon nanotubes

    Science.gov (United States)

    Strano, Michael S. (Inventor); Usrey, Monica (Inventor); Barone, Paul (Inventor); Dyke, Christopher A. (Inventor); Tour, James M. (Inventor); Kittrell, W. Carter (Inventor); Hauge, Robert H. (Inventor); Smalley, Richard E. (Inventor)

    2009-01-01

    The present invention is directed toward methods of selectively functionalizing carbon nanotubes of a specific type or range of types, based on their electronic properties, using diazonium chemistry. The present invention is also directed toward methods of separating carbon nanotubes into populations of specific types or range(s) of types via selective functionalization and electrophoresis, and also to the novel compositions generated by such separations.

  7. Simulating natural selection in landscape genetics

    Science.gov (United States)

    E. L. Landguth; S. A. Cushman; N. Johnson

    2012-01-01

    Linking landscape effects to key evolutionary processes through individual organism movement and natural selection is essential to provide a foundation for evolutionary landscape genetics. Of particular importance is determining how spatially- explicit, individual-based models differ from classic population genetics and evolutionary ecology models based on ideal...

  8. Exploiting a natural auxotrophy for genetic selection.

    Science.gov (United States)

    Ramage, Elizabeth; Gallagher, Larry; Manoil, Colin

    2012-08-01

    We exploited the natural histidine auxotrophy of Francisella species to develop hisD (encodes histidinol dehydrogenase) as a positive selection marker. A shuttle plasmid (pBR103) carrying Escherichia coli hisD and designed for cloning of PCR fragments replicated in both attenuated and highly virulent Francisella strains. During this work, we formulated a simplified defined growth medium for Francisella novicida.

  9. A Lesson on Evolution & Natural Selection

    Science.gov (United States)

    Curtis, Anthony D.

    2010-01-01

    I describe three activities that allow students to explore the ideas of evolution, natural selection, extinction, mass extinction, and rates of evolutionary change by engaging a simple model using paper, pens, chalk, and a chalkboard. As a culminating activity that supports expository writing in the sciences, the students write an essay on mass…

  10. Natural selection. VII. History and interpretation of kin selection theory.

    Science.gov (United States)

    Frank, S A

    2013-06-01

    Kin selection theory is a kind of causal analysis. The initial form of kin selection ascribed cause to costs, benefits and genetic relatedness. The theory then slowly developed a deeper and more sophisticated approach to partitioning the causes of social evolution. Controversy followed because causal analysis inevitably attracts opposing views. It is always possible to separate total effects into different component causes. Alternative causal schemes emphasize different aspects of a problem, reflecting the distinct goals, interests and biases of different perspectives. For example, group selection is a particular causal scheme with certain advantages and significant limitations. Ultimately, to use kin selection theory to analyse natural patterns and to understand the history of debates over different approaches, one must follow the underlying history of causal analysis. This article describes the history of kin selection theory, with emphasis on how the causal perspective improved through the study of key patterns of natural history, such as dispersal and sex ratio, and through a unified approach to demographic and social processes. Independent historical developments in the multivariate analysis of quantitative traits merged with the causal analysis of social evolution by kin selection. © 2013 The Author. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

  11. Missing concepts in natural selection theory reconstructions.

    Science.gov (United States)

    Ginnobili, Santiago

    2016-09-01

    The concept of fitness has generated a lot of discussion in philosophy of biology. There is, however, relative agreement about the need to distinguish at least two uses of the term: ecological fitness on the one hand, and population genetics fitness on the other. The goal of this paper is to give an explication of the concept of ecological fitness by providing a reconstruction of the theory of natural selection in which this concept was framed, that is, based on the way the theory was put to use in Darwin's main texts. I will contend that this reconstruction enables us to account for the current use of the theory of natural selection. The framework presupposed in the analysis will be that of metatheoretical structuralism. This framework will provide both a better understanding of the nature of ecological fitness and a more complete reconstruction of the theory. In particular, it will provide what I think is a better way of understanding how the concept of fitness is applied through heterogeneous cases. One of the major advantages of my way of thinking about natural selection theory is that it would not have the peculiar metatheoretical status that it has in other available views. I will argue that in order to achieve these goals it is necessary to make several concepts explicit, concepts that are frequently omitted in usual reconstructions.

  12. A selected bibliography on natural radiation, 1

    International Nuclear Information System (INIS)

    Abe, Siro; Abe, Michiko; Fujitaka, Kazunobu; Fujimoto, Kenzo.

    1977-03-01

    Natural radioactive substances in the environment are important in general scientific research and impacts on human beings. The natural levels of radiations are then involved in peaceful uses of nuclear energy. The present bibliography is intended to meet the needs in this field. Entries complete with an abstract are selected from Nuclear Science Abstracts of vol. 1 (1948) to vol. 32 (December 1975). Only the primordial radionuclides as follows, without series, are treated concerning the levels, measurements, etc. : 40 K, 50 V, 87 Rb, 115 In, 123 Te, 138 La, 142 Ce, 144 Nd, 147 Sm, 152 Gd, 176 Lu, 174 Hf, 187 Re, and 190 Pt. (Mori, K.)

  13. Nullomers: really a matter of natural selection?

    Directory of Open Access Journals (Sweden)

    Claudia Acquisti

    2007-10-01

    Full Text Available Nullomers are short DNA sequences that are absent from the genomes of humans and other species. Assuming that nullomers are the signatures of natural selection against deleterious sequences in humans, the use of nullomers in drug target identification, pesticide development, environmental monitoring, and forensic applications has been envisioned.Here, we show that the hypermutability of CpG dinucleotides, rather than the natural selection against the nullomer sequences, is likely the reason for the phenomenal event of short sequence motifs becoming nullomers. Furthermore, many reported human nullomers differ by only one nucleotide, which reinforces the role of mutation in the evolution of the constellation of nullomers in populations and species. The known nullomers in chimpanzee, cow, dog, and mouse genomes show patterns that are consistent with those seen in humans.The role of mutations, instead of selection, in generating nullomers cast doubt on the utility of nullomers in many envisioned applications, because of their dependence on the role of lethal selection on the origin of nullomers.

  14. Selective Functionalization of Arbitrary Nanowires

    Science.gov (United States)

    2006-11-02

    3-mercaptopropyl)- trimethoxysilane (MPTMS). The wires were grown electrochemically in anodic aluminum oxide ( AAO ) templates. Selective deposition...In the past, templates composed of polycarbonate track-etched membranes or anodic aluminum oxide materials have been used for the construction of...modifier MPTMS was used to function- alize the AAO template because it can form covalent bonds with silanes and metal oxide surfaces21 and because of

  15. Selective covers for natural cooling devices

    International Nuclear Information System (INIS)

    Addeo, A.; Monza, E.; Peraldo, M.; Bartoli, B.; Coluzzi, B.; Silvestrini, V.; Troise, G.

    1978-01-01

    Extra-atmospheric space is practically a pure sink of radiation, and can be used as a nonconventional energy source. In previous papers it has been shown that surfaces with an emissivity matched with the atmospheric (8/13)μm ''transparency window'' (natural emitters) interact with cold space when exposed to clear sky at night, and undergo a sizable cooling effect. In this paper, starting from experimental results concerning the diurnal performances of natural emitters, the problem of their interaction with solar radiation is discussed, and the use is proposed of selective covers which shade the emitter from solar radiation, without preventing the interaction with cold space via emission of infra-red radiation. (author)

  16. Can natural selection encode Bayesian priors?

    Science.gov (United States)

    Ramírez, Juan Camilo; Marshall, James A R

    2017-08-07

    The evolutionary success of many organisms depends on their ability to make decisions based on estimates of the state of their environment (e.g., predation risk) from uncertain information. These decision problems have optimal solutions and individuals in nature are expected to evolve the behavioural mechanisms to make decisions as if using the optimal solutions. Bayesian inference is the optimal method to produce estimates from uncertain data, thus natural selection is expected to favour individuals with the behavioural mechanisms to make decisions as if they were computing Bayesian estimates in typically-experienced environments, although this does not necessarily imply that favoured decision-makers do perform Bayesian computations exactly. Each individual should evolve to behave as if updating a prior estimate of the unknown environment variable to a posterior estimate as it collects evidence. The prior estimate represents the decision-maker's default belief regarding the environment variable, i.e., the individual's default 'worldview' of the environment. This default belief has been hypothesised to be shaped by natural selection and represent the environment experienced by the individual's ancestors. We present an evolutionary model to explore how accurately Bayesian prior estimates can be encoded genetically and shaped by natural selection when decision-makers learn from uncertain information. The model simulates the evolution of a population of individuals that are required to estimate the probability of an event. Every individual has a prior estimate of this probability and collects noisy cues from the environment in order to update its prior belief to a Bayesian posterior estimate with the evidence gained. The prior is inherited and passed on to offspring. Fitness increases with the accuracy of the posterior estimates produced. Simulations show that prior estimates become accurate over evolutionary time. In addition to these 'Bayesian' individuals, we also

  17. Hard and Soft Selection Revisited: How Evolution by Natural Selection Works in the Real World.

    Science.gov (United States)

    Reznick, David

    2016-01-01

    The modern synthesis of evolutionary biology unified Darwin's natural selection with Mendelian genetics, but at the same time it created the dilemma of genetic load. Lewontin and Hubby's (1966) and Harris's (1966) characterization of genetic variation in natural populations increased the apparent burden of this load. Neutrality or near neutrality of genetic variation was one mechanism proposed for the revealed excessive genetic variation. Bruce Wallace coined the term "soft selection" to describe an alternative way for natural selection to operate that was consistent with observed variation. He envisioned nature as presenting ecological vacancies that could be filled by diverse genotypes. Survival and successful reproduction was a combined function of population density, genotype, and genotype frequencies, rather than a fixed value of the relative fitness of each genotype. My goal in this review is to explore the importance of soft selection in the real world. My motive and that of my colleagues as described here is not to explain what maintains genetic variation in natural populations, but rather to understand the factors that shape how organisms adapt to natural environments. We characterize how feedbacks between ecology and evolution shape both evolution and ecology. These feedbacks are mediated by density- and frequency-dependent selection, the mechanisms that underlie soft selection. Here, I report on our progress in characterizing these types of selection with a combination of a consideration of the published literature and the results from my collaborators' and my research on natural populations of guppies. © The American Genetic Association. 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Using Card Games to Simulate the Process of Natural Selection

    Science.gov (United States)

    Grilliot, Matthew E.; Harden, Siegfried

    2014-01-01

    In 1858, Darwin published "On the Origin of Species by Means of Natural Selection." His explanation of evolution by natural selection has become the unifying theme of biology. We have found that many students do not fully comprehend the process of evolution by natural selection. We discuss a few simple games that incorporate hands-on…

  19. Bridging Emergent Attributes and Darwinian Principles in Teaching Natural Selection

    Science.gov (United States)

    Xu, Dongchen; Chi, Michelene T. H.

    2016-01-01

    Students often have misconceptions about natural selection as they misuse a direct causal schema to explain the process. Natural selection is in fact an emergent process where random interactions lead to changes in a population. The misconceptions stem from students' lack of emergent schema for natural selection. In order to help students…

  20. Natural selection and the elusiveness of happiness.

    Science.gov (United States)

    Nesse, Randolph M

    2004-09-29

    The quest for happiness has expanded from a focus on relieving suffering to also considering how to promote happiness. However, both approaches have yet to be conducted in an evolutionary framework based on the situations that shaped the capacities for happiness and sadness. Because of this, the emphasis has almost all been on the disadvantages of negative states and the benefits of positive states, to the nearly total neglect of 'diagonal psychology', which also considers the dangers of unwarranted positive states and the benefits of negative emotions in certain situations. The situations that arise in goal pursuit contain adaptive challenges that have shaped domain-general positive and negative emotions that were partially differentiated by natural selection to cope with the more specific situations that arise in the pursuit of different kinds of goals. In cultures where large social groups give rise to specialized and competitive social roles, depression may be common because regulation systems are pushed far beyond the bounds for which they were designed. Research on the evolutionary origins of the capacities for positive and negative emotions is urgently needed to provide a foundation for sensible decisions about the use of new mood-manipulating technologies.

  1. Natural selection and infectious disease in human populations

    Science.gov (United States)

    Karlsson, Elinor K.; Kwiatkowski, Dominic P.; Sabeti, Pardis C.

    2015-01-01

    The ancient biological 'arms race' between microbial pathogens and humans has shaped genetic variation in modern populations, and this has important implications for the growing field of medical genomics. As humans migrated throughout the world, populations encountered distinct pathogens, and natural selection increased the prevalence of alleles that are advantageous in the new ecosystems in both host and pathogens. This ancient history now influences human infectious disease susceptibility and microbiome homeostasis, and contributes to common diseases that show geographical disparities, such as autoimmune and metabolic disorders. Using new high-throughput technologies, analytical methods and expanding public data resources, the investigation of natural selection is leading to new insights into the function and dysfunction of human biology. PMID:24776769

  2. Sexual and Natural Selection Both Influence Male Genital Evolution

    OpenAIRE

    House, Clarissa M.; Lewis, Zenobia; Hodgson, Dave J.; Wedell, Nina; Sharma, Manmohan D.; Hunt, John; Hosken, David J.

    2013-01-01

    Rapid and divergent evolution of male genital morphology is a conspicuous and general pattern across internally fertilizing animals. Rapid genital evolution is thought to be the result of sexual selection, and the role of natural selection in genital evolution remains controversial. However, natural and sexual selection are believed to act antagonistically on male genital form. We conducted an experimental evolution study to investigate the combined effects of natural and sexual selection on ...

  3. Dual Functions of Natural Killer Cells in Selection and Differentiation of Stem Cells; Role in Regulation of Inflammation and Regeneration of Tissues

    Directory of Open Access Journals (Sweden)

    Anahid Jewett, Yan-Gao Man, Han-Ching Tseng

    2013-01-01

    Full Text Available Accumulated evidence from our laboratory indicates that conditioned or anergized NK cells have the ability to induce resistance of healthy stem cells and transformed cancer stem cells through both secreted factors and direct cell-cell contact by inducing differentiation. Cytotoxic function of NK cells is suppressed in the tumor microenvironment by a number of distinct effectors and their secreted factors. Furthermore, decreased peripheral blood NK cell function has been documented in many cancer patients. We have previously shown that NK cells mediate significant cytotoxicity against primary oral squamous carcinoma stem cells (OSCSCs as compared to their more differentiated oral squamous carcinoma cells (OSCCs. In addition, human embryonic stem cells (hESCs, human mesenchymal stem cells (hMSCs, human dental pulp stem cells (hDPSCs and induced human pluripotent stem cells (hiPSCs were all significantly more susceptible to NK cell mediated cytotoxicity than their differentiated counterparts or parental cells from which they were derived. We have also reported that inhibition of differentiation or reversion of cells to a less-differentiated phenotype by blocking NFκB or gene deletion of COX2 significantly augmented NK cell function. Furthermore, the induction of resistance of the stem cells to NK cell mediated cytotoxicity and their subsequent differentiation is amplified when either the stem cells or the NK cells were cultured in the presence of monocytes. Therefore, we propose that the two stages of NK cell maturation namely CD16+CD56dimCD69- NK cells are important for the lysis of stem cells or poorly differentiated cells whereas the CD16dim/-CD56dim/+CD69+NK cells are important for differentiation and eventual regeneration of the tissues and the resolution of inflammation, thus functionally serving as regulatory NK cells (NKreg. CD16 receptor on the NK cells were found to be the receptor with significant potential to induce NK cell anergy

  4. A Conceptual Characterization of Online Videos Explaining Natural Selection

    Science.gov (United States)

    Bohlin, Gustav; Göransson, Andreas; Höst, Gunnar E.; Tibell, Lena A. E.

    2017-11-01

    Educational videos on the Internet comprise a vast and highly diverse source of information. Online search engines facilitate access to numerous videos claiming to explain natural selection, but little is known about the degree to which the video content match key evolutionary content identified as important in evolution education research. In this study, we therefore analyzed the content of 60 videos accessed through the Internet, using a criteria catalog with 38 operationalized variables derived from research literature. The variables were sorted into four categories: (a) key concepts (e.g. limited resources and inherited variation), (b) threshold concepts (abstract concepts with a transforming and integrative function), (c) misconceptions (e.g. that evolution is driven by need), and (d) organismal context (e.g. animal or plant). The results indicate that some concepts are frequently communicated, and certain taxa are commonly used to illustrate concepts, while others are seldom included. In addition, evolutionary phenomena at small temporal and spatial scales, such as subcellular processes, are rarely covered. Rather, the focus is on population-level events over time scales spanning years or longer. This is consistent with an observed lack of explanations regarding how randomly occurring mutations provide the basis for variation (and thus natural selection). The findings imply, among other things, that some components of natural selection warrant far more attention in biology teaching and science education research.

  5. The Emergence of Physiology and Form: Natural Selection Revisited

    Science.gov (United States)

    Torday, John S.

    2016-01-01

    Natural Selection describes how species have evolved differentially, but it is descriptive, non-mechanistic. What mechanisms does Nature use to accomplish this feat? One known way in which ancient natural forces affect development, phylogeny and physiology is through gravitational effects that have evolved as mechanotransduction, seen in the lung, kidney and bone, linking as molecular homologies to skin and brain. Tracing the ontogenetic and phylogenetic changes that have facilitated mechanotransduction identifies specific homologous cell-types and functional molecular markers for lung homeostasis that reveal how and why complex physiologic traits have evolved from the unicellular to the multicellular state. Such data are reinforced by their reverse-evolutionary patterns in chronic degenerative diseases. The physiologic responses of model organisms like Dictyostelium and yeast to gravity provide deep comparative molecular phenotypic homologies, revealing mammalian Target of Rapamycin (mTOR) as the final common pathway for vertical integration of vertebrate physiologic evolution; mTOR integrates calcium/lipid epistatic balance as both the proximate and ultimate positive selection pressure for vertebrate physiologic evolution. The commonality of all vertebrate structure-function relationships can be reduced to calcium/lipid homeostatic regulation as the fractal unit of vertebrate physiology, demonstrating the primacy of the unicellular state as the fundament of physiologic evolution. PMID:27534726

  6. ENHANCEMENTS TO NATURAL ATTENUATION: SELECTED CASE STUDIES

    Energy Technology Data Exchange (ETDEWEB)

    Vangelas, K; W. H. Albright, W; E. S. Becvar, E; C. H. Benson, C; T. O. Early, T; E. Hood, E; P. M. Jardine, P; M. Lorah, M; E. Majche, E; D. Major, D; W. J. Waugh, W; G. Wein, G; O. R. West, O

    2007-05-15

    In 2003 the US Department of Energy (DOE) embarked on a project to explore an innovative approach to remediation of subsurface contaminant plumes that focused on introducing mechanisms for augmenting natural attenuation to achieve site closure. Termed enhanced attenuation (EA), this approach has drawn its inspiration from the concept of monitored natural attenuation (MNA).

  7. Microbial Resistance to Triclosan: A Case Study in Natural Selection

    Science.gov (United States)

    Serafini, Amanda; Matthews, Dorothy M.

    2009-01-01

    Natural selection is the mechanism of evolution caused by the environmental selection of organisms most fit to reproduce, sometimes explained as "survival of the fittest." An example of evolution by natural selection is the development of bacteria that are resistant to antimicrobial agents as a result of exposure to these agents. Triclosan, which…

  8. Software For Computing Selected Functions

    Science.gov (United States)

    Grant, David C.

    1992-01-01

    Technical memorandum presents collection of software packages in Ada implementing mathematical functions used in science and engineering. Provides programmer with function support in Pascal and FORTRAN, plus support for extended-precision arithmetic and complex arithmetic. Valuable for testing new computers, writing computer code, or developing new computer integrated circuits.

  9. Natural selection against a circadian clock gene mutation in mice.

    Science.gov (United States)

    Spoelstra, Kamiel; Wikelski, Martin; Daan, Serge; Loudon, Andrew S I; Hau, Michaela

    2016-01-19

    Circadian rhythms with an endogenous period close to or equal to the natural light-dark cycle are considered evolutionarily adaptive ("circadian resonance hypothesis"). Despite remarkable insight into the molecular mechanisms driving circadian cycles, this hypothesis has not been tested under natural conditions for any eukaryotic organism. We tested this hypothesis in mice bearing a short-period mutation in the enzyme casein kinase 1ε (tau mutation), which accelerates free-running circadian cycles. We compared daily activity (feeding) rhythms, survivorship, and reproduction in six replicate populations in outdoor experimental enclosures, established with wild-type, heterozygous, and homozygous mice in a Mendelian ratio. In the release cohort, survival was reduced in the homozygote mutant mice, revealing strong selection against short-period genotypes. Over the course of 14 mo, the relative frequency of the tau allele dropped from initial parity to 20%. Adult survival and recruitment of juveniles into the population contributed approximately equally to the selection for wild-type alleles. The expression of activity during daytime varied throughout the experiment and was significantly increased by the tau mutation. The strong selection against the short-period tau allele observed here contrasts with earlier studies showing absence of selection against a Period 2 (Per2) mutation, which disrupts internal clock function, but does not change period length. These findings are consistent with, and predicted by the theory that resonance of the circadian system plays an important role in individual fitness.

  10. Supplier selection using different metric functions

    Directory of Open Access Journals (Sweden)

    Omosigho S.E.

    2015-01-01

    Full Text Available Supplier selection is an important component of supply chain management in today’s global competitive environment. Hence, the evaluation and selection of suppliers have received considerable attention in the literature. Many attributes of suppliers, other than cost, are considered in the evaluation and selection process. Therefore, the process of evaluation and selection of suppliers is a multi-criteria decision making process. The methodology adopted to solve the supplier selection problem is intuitionistic fuzzy TOPSIS (Technique for Order Preference by Similarity to the Ideal Solution. Generally, TOPSIS is based on the concept of minimum distance from the positive ideal solution and maximum distance from the negative ideal solution. We examine the deficiencies of using only one metric function in TOPSIS and propose the use of spherical metric function in addition to the commonly used metric functions. For empirical supplier selection problems, more than one metric function should be used.

  11. Natural and sexual selection against hybrid flycatchers

    NARCIS (Netherlands)

    Svedin, Nina; Wiley, Chris; Veen, Thor; Gustafsson, Lars; Qvarnstrom, Anna

    2008-01-01

    While sexual selection is generally assumed to quickly cause or strengthen prezygotic barriers between sister species, its role in causing postzygotic isolation, through the unattractiveness of intermediate hybrids, is less often examined. Combining 24 years of pedigree data and recently developed

  12. Case studies on selected natural food antioxidants

    OpenAIRE

    Herrero, Miguel; Mendiola, J. A.; Cifuentes, Alejandro; Ibáñez, Elena

    2013-01-01

    In this chapter, a broad description of several case studies related to common antioxidants found in food-related products is presented. In this regard, special attention is put on the novel advanced environmentally-friendly extraction methods nowadays employed to extract and purify those potent antioxidants from natural matrices. A brief description of these extraction processes is provided together with some of the instrumentation needed. Besides, the studies carried out so f...

  13. Natural Selection in the Field and the Classroom

    Science.gov (United States)

    Andrews, Tessa Marie

    2012-01-01

    This dissertation examined natural selection in westslope cutthroat trout ("Oncorhynchus clarkii lewisi") and undergraduate learning in the subject area natural selection. Translocation--moving individuals to a new habitat to establish, re-establish or supplement a population--is a crucial management strategy for cutthroat trout. One of…

  14. Nutrient selection by cattle, goats and sheep on natural Karoo ...

    African Journals Online (AJOL)

    Nutrient selection by cattle, goats and sheep on natural. Karoo pasture. 2. Nitrogen. P.J.L.Zeeman, P.G. Marais and M.J. Coetsee. Research Institute of the Karoo Region, Middelburg, Cape. The nitrogen (N) content of material selected by cattle, Boer goats,. Dorper and Merino sheep on natural Karoo pasture was ...

  15. Are Humans Still Evolving? A Natural Selection Discussion Lesson

    Science.gov (United States)

    Shields, Martin

    2004-01-01

    A study is conducted to develop sound comprehension of natural selection theory by prompting students to use its concept to explain the evolutionary status of humans. In relation to the current existence of human it is stated that human populations currently undergo microevolutionary changes in allele frequencies due to natural selection and other…

  16. A Working Model of Natural Selection Illustrated by Table Tennis

    Science.gov (United States)

    Dinc, Muhittin; Kilic, Selda; Aladag, Caner

    2013-01-01

    Natural selection is one of the most important topics in biology and it helps to clarify the variety and complexity of organisms. However, students in almost every stage of education find it difficult to understand the mechanism of natural selection and they can develop misconceptions about it. This article provides an active model of natural…

  17. Getting to Darwin: Obstacles to Accepting Evolution by Natural Selection

    Science.gov (United States)

    Thagard, Paul; Findlay, Scott

    2010-01-01

    Darwin's theory of evolution by natural selection is central to modern biology, but is resisted by many people. This paper discusses the major psychological obstacles to accepting Darwin's theory. Cognitive obstacles to adopting evolution by natural selection include conceptual difficulties, methodological issues, and coherence problems that…

  18. Rational Density Functional Selection Using Game Theory.

    Science.gov (United States)

    McAnanama-Brereton, Suzanne; Waller, Mark P

    2018-01-22

    Theoretical chemistry has a paradox of choice due to the availability of a myriad of density functionals and basis sets. Traditionally, a particular density functional is chosen on the basis of the level of user expertise (i.e., subjective experiences). Herein we circumvent the user-centric selection procedure by describing a novel approach for objectively selecting a particular functional for a given application. We achieve this by employing game theory to identify optimal functional/basis set combinations. A three-player (accuracy, complexity, and similarity) game is devised, through which Nash equilibrium solutions can be obtained. This approach has the advantage that results can be systematically improved by enlarging the underlying knowledge base, and the deterministic selection procedure mathematically justifies the density functional and basis set selections.

  19. Morus alba L. nature's functional tonic

    NARCIS (Netherlands)

    Butt, M.S.; Nazir, A.; Tauseef Sultan, M.; Schroën, C.G.P.H.

    2008-01-01

    Currently, importance of natural products is being revitalized to alleviate various health discrepancies. The link between health and diet is well documented and the consumers' trend reflects conscience towards their dietary habits. Probing these links has led to the emergence of functional,

  20. Percieved functions of naturally occurring autobiographical memories

    DEFF Research Database (Denmark)

    Treebak, L. S.; Henriksen, J. R.; Lundhus, S.

    2005-01-01

    The main empirical reference on functions of autobiographical memories is still Hyman & Faries (1992) who used the cue-word-method and retrospective judgements. We used diaries to sample naturally occurring autobiographical memories and participants? perceived use of these. Results partly replicate...

  1. Utilization of Natural Products as Functional Feed

    Directory of Open Access Journals (Sweden)

    Stella Magdalena

    2013-03-01

    Full Text Available The use of antibiotics as feed additive improves performance in livestock. However, scientific data related to the use of antibiotics in feed merge spreading of bacterial resistance in animal and human bodies, therefore the usage of antibiotics in animal production is restricted. This condition raise the utilization of natural antibiotic as functional feed such as phytogenics (essential oil, flavonoid, saponin, and tannin, enzyme, probiotic, and prebiotic to improve the livestock’s performance, quality, and health. Functional feeds increase profitability in animal husbandry production and its use is feeds are expected to be functional foods that may have positive effects in human nutrition.

  2. Hazard function theory for nonstationary natural hazards

    Science.gov (United States)

    Read, L.; Vogel, R. M.

    2015-12-01

    Studies from the natural hazards literature indicate that many natural processes, including wind speeds, landslides, wildfires, precipitation, streamflow and earthquakes, show evidence of nonstationary behavior such as trends in magnitudes through time. Traditional probabilistic analysis of natural hazards based on partial duration series (PDS) generally assumes stationarity in the magnitudes and arrivals of events, i.e. that the probability of exceedance is constant through time. Given evidence of trends and the consequent expected growth in devastating impacts from natural hazards across the world, new methods are needed to characterize their probabilistic behavior. The field of hazard function analysis (HFA) is ideally suited to this problem because its primary goal is to describe changes in the exceedance probability of an event over time. HFA is widely used in medicine, manufacturing, actuarial statistics, reliability engineering, economics, and elsewhere. HFA provides a rich theory to relate the natural hazard event series (x) with its failure time series (t), enabling computation of corresponding average return periods and reliabilities associated with nonstationary event series. This work investigates the suitability of HFA to characterize nonstationary natural hazards whose PDS magnitudes are assumed to follow the widely applied Poisson-GP model. We derive a 2-parameter Generalized Pareto hazard model and demonstrate how metrics such as reliability and average return period are impacted by nonstationarity and discuss the implications for planning and design. Our theoretical analysis linking hazard event series x, with corresponding failure time series t, should have application to a wide class of natural hazards.

  3. Anodic selective functionalization of cyclic amine derivatives

    OpenAIRE

    Onomura, Osamu

    2012-01-01

    Anodic reactions are desirable methods from the viewpoint of Green Chemistry, since no toxic oxidants are necessary for the oxidation of organic molecules. This review introduces usefulness of anodic oxidation and successive reaction for selective functionalization of cyclic amine derivatives.

  4. Innovative natural functional ingredients from microalgae.

    Science.gov (United States)

    Plaza, Merichel; Herrero, Miguel; Cifuentes, Alejandro; Ibáñez, Elena

    2009-08-26

    Nowadays, a wide variety of compounds such as polyphenols, polyunsaturated fatty acids (PUFA), or phytosterols obtained, for example, from wine, fish byproducts, or plants are employed to prepare new functional foods. However, unexplored natural sources of bioactive ingredients are gaining much attention since they can lead to the discovery of new compounds or bioactivities. Microalgae have been proposed as an interesting, almost unlimited, natural source in the search for novel natural functional ingredients, and several works have shown the possibility to find bioactive compounds in these organisms. Some advantages can be associated with the study of microalgae such as their huge diversity, the possibility of being used as natural reactors at controlled conditions, and their ability to produce active secondary metabolites to defend themselves from adverse or extreme conditions. In this contribution, an exhaustive revision is presented involving the research for innovative functional food ingredients from microalgae. The most interesting results in this promising field are discussed including new species composition and bioactivity and new processing and extraction methods. Moreover, the future research trends are critically commented.

  5. Hazard function theory for nonstationary natural hazards

    Science.gov (United States)

    Read, Laura K.; Vogel, Richard M.

    2016-04-01

    Impact from natural hazards is a shared global problem that causes tremendous loss of life and property, economic cost, and damage to the environment. Increasingly, many natural processes show evidence of nonstationary behavior including wind speeds, landslides, wildfires, precipitation, streamflow, sea levels, and earthquakes. Traditional probabilistic analysis of natural hazards based on peaks over threshold (POT) generally assumes stationarity in the magnitudes and arrivals of events, i.e., that the probability of exceedance of some critical event is constant through time. Given increasing evidence of trends in natural hazards, new methods are needed to characterize their probabilistic behavior. The well-developed field of hazard function analysis (HFA) is ideally suited to this problem because its primary goal is to describe changes in the exceedance probability of an event over time. HFA is widely used in medicine, manufacturing, actuarial statistics, reliability engineering, economics, and elsewhere. HFA provides a rich theory to relate the natural hazard event series (X) with its failure time series (T), enabling computation of corresponding average return periods, risk, and reliabilities associated with nonstationary event series. This work investigates the suitability of HFA to characterize nonstationary natural hazards whose POT magnitudes are assumed to follow the widely applied generalized Pareto model. We derive the hazard function for this case and demonstrate how metrics such as reliability and average return period are impacted by nonstationarity and discuss the implications for planning and design. Our theoretical analysis linking hazard random variable X with corresponding failure time series T should have application to a wide class of natural hazards with opportunities for future extensions.

  6. Selective functionalization of patterned glass surfaces

    NARCIS (Netherlands)

    Ploetz, E.; Visser, B.; Slingenbergh, W.; Evers, K.; Martinez-Martinez, D.; Pei, Y. T.; Feringa, B. L.; De Hosson, J. Th. M.; Cordes, T.; van Dorp, W. F.

    2014-01-01

    Tailored writing and specific positioning of molecules on nanostructures is a key step for creating functional materials and nano-optical devices, or interfaces for synthetic machines in various applications. We present a novel approach for the selective functionalization of patterned glass surfaces

  7. The selection function of the RAVE survey

    NARCIS (Netherlands)

    Wojno, Jennifer; Kordopatis, Georges; Piffl, Tilmann; Binney, James; Steinmetz, Matthias; Matijevič, Gal; Bland-Hawthorn, Joss; Sharma, Sanjib; McMillan, Paul; Watson, Fred; Reid, Warren; Kunder, Andrea; Enke, Harry; Grebel, Eva K.; Seabroke, George; Wyse, Rosemary F. G.; Zwitter, Tomaž; Bienaymé, Olivier; Freeman, Kenneth C.; Gibson, Brad K.; Gilmore, Gerry; Helmi, Amina; Munari, Ulisse; Navarro, Julio F.; Parker, Quentin A.; Siebert, Arnaud

    2017-01-01

    We characterize the selection function of RAdial Velocity Experiment (RAVE) using 2 Micron All Sky Survey (2MASS) as our underlying population, which we assume represents all stars that could have potentially been observed. We evaluate the completeness fraction as a function of position, magnitude

  8. Natural Selection Is a Sorting Process: What Does that Mean?

    Science.gov (United States)

    Price, Rebecca M.

    2013-01-01

    To learn why natural selection acts only on existing variation, students categorize processes as either creative or sorting. This activity helps students confront the misconception that adaptations evolve because species need them.

  9. Utilization of Natural Products as Functional Feed

    OpenAIRE

    Stella Magdalena; Natadiputri G H; Nailufar; Purwadaria T

    2013-01-01

    The use of antibiotics as feed additive improves performance in livestock. However, scientific data related to the use of antibiotics in feed merge spreading of bacterial resistance in animal and human bodies, therefore the usage of antibiotics in animal production is restricted. This condition raise the utilization of natural antibiotic as functional feed such as phytogenics (essential oil, flavonoid, saponin, and tannin), enzyme, probiotic, and prebiotic to improve the livestock’s performan...

  10. Natural Selection as an Emergent Process: Instructional Implications

    Science.gov (United States)

    Cooper, Robert A.

    2017-01-01

    Student reasoning about cases of natural selection is often plagued by errors that stem from miscategorising selection as a direct, causal process, misunderstanding the role of randomness, and from the intuitive ideas of intentionality, teleology and essentialism. The common thread throughout many of these reasoning errors is a failure to apply…

  11. Giant Panda habitat selection in the Foping Nature Reserve, China

    NARCIS (Netherlands)

    Liu, X.; Toxopeus, A.G.; Skidmore, A.K.; Shao, X.; Dang, D.; Wang, T.; Prins, H.H.T.

    2005-01-01

    Little is known about habitat selection of the giant panda (Ailuropoda melanoleuca), especially about the relationship between giant panda presence and bamboo and tree structures. We presented data on giant panda habitat use and selection in Foping Nature Reserve (NR), China. We used 1,066

  12. The genetic consequences of selection in natural populations.

    Science.gov (United States)

    Thurman, Timothy J; Barrett, Rowan D H

    2016-04-01

    The selection coefficient, s, quantifies the strength of selection acting on a genetic variant. Despite this parameter's central importance to population genetic models, until recently we have known relatively little about the value of s in natural populations. With the development of molecular genetic techniques in the late 20th century and the sequencing technologies that followed, biologists are now able to identify genetic variants and directly relate them to organismal fitness. We reviewed the literature for published estimates of natural selection acting at the genetic level and found over 3000 estimates of selection coefficients from 79 studies. Selection coefficients were roughly exponentially distributed, suggesting that the impact of selection at the genetic level is generally weak but can occasionally be quite strong. We used both nonparametric statistics and formal random-effects meta-analysis to determine how selection varies across biological and methodological categories. Selection was stronger when measured over shorter timescales, with the mean magnitude of s greatest for studies that measured selection within a single generation. Our analyses found conflicting trends when considering how selection varies with the genetic scale (e.g., SNPs or haplotypes) at which it is measured, suggesting a need for further research. Besides these quantitative conclusions, we highlight key issues in the calculation, interpretation, and reporting of selection coefficients and provide recommendations for future research. © 2016 John Wiley & Sons Ltd.

  13. Assortment and the analysis of natural selection on social traits.

    Science.gov (United States)

    McDonald, Grant C; Farine, Damien R; Foster, Kevin R; Biernaskie, Jay M

    2017-11-01

    A central problem in evolutionary biology is to determine whether and how social interactions contribute to natural selection. A key method for phenotypic data is social selection analysis, in which fitness effects from social partners contribute to selection only when there is a correlation between the traits of individuals and their social partners (nonrandom phenotypic assortment). However, there are inconsistencies in the use of social selection that center around the measurement of phenotypic assortment. Here, we use data analysis and simulations to resolve these inconsistencies, showing that: (i) not all measures of assortment are suitable for social selection analysis; and (ii) the interpretation of assortment, and how to detect nonrandom assortment, will depend on the scale at which it is measured. We discuss links to kin selection theory and provide a practical guide for the social selection approach. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  14. What Is "Natural"? Consumer Responses to Selected Ingredients.

    Science.gov (United States)

    Chambers, Edgar; Chambers, Edgar; Castro, Mauricio

    2018-04-23

    Interest in “natural” food has grown enormously over the last decade. Because the United States government has not set a legal definition for the term “natural”, customers have formed their own sensory perceptions and opinions on what constitutes natural. In this study, we examined 20 ingredients to determine what consumers consider to be natural. Using a national database, 630 consumers were sampled (50% male and 50% female) online, and the results were analyzed using percentages and chi-square tests. No ingredient was considered natural by more than 69% of respondents. We found evidence that familiarity may play a major role in consumers’ determination of naturalness. We also found evidence that chemical sounding names and the age of the consumer have an effect on whether an ingredient and potentially a food is considered natural. Interestingly, a preference towards selecting GMO (genetically modified organisms) foods had no significant impact on perceptions of natural.

  15. Getting to Darwin: Obstacles to Accepting Evolution by Natural Selection

    Science.gov (United States)

    Thagard, Paul; Findlay, Scott

    2010-06-01

    Darwin’s theory of evolution by natural selection is central to modern biology, but is resisted by many people. This paper discusses the major psychological obstacles to accepting Darwin’s theory. Cognitive obstacles to adopting evolution by natural selection include conceptual difficulties, methodological issues, and coherence problems that derive from the intuitiveness of alternative theories. The main emotional obstacles to accepting evolution are its apparent conflict with valued beliefs about God, souls, and morality. We draw on the philosophy of science and on a psychological theory of cognitive and emotional belief revision to make suggestions about what can be done to improve acceptance of Darwinian ideas.

  16. Selection method and characterization of neutron monochromator natural crystals

    International Nuclear Information System (INIS)

    Stasiulevicius, R.; Kastner, G.F.

    2000-01-01

    Thermal neutrons are important analytical tools for microscopic material probe. These neutrons can be selected by diffraction technique using monocrystal, usually artificial. A crystal selection process was implemented and the characteristics of natural specimens were studied by activation analysis-k 0 method. The representative 120 samples, of which 21 best types, were irradiated in IPR-R1 and measured with a neutron diffractometer at IEA-R1m Brazilian reactors. These results are useful for database build up and ease the choice of appropriate natural crystal, with some advantage options: highest intensity diffracted, enlarging the energy operational interval and optimal performance in special applications. (author)

  17. Natural selection on floral morphology can be influenced by climate.

    Science.gov (United States)

    Campbell, Diane R; Powers, John M

    2015-06-07

    Climate has the potential to influence evolution, but how it influences the strength or direction of natural selection is largely unknown. We quantified the strength of selection on four floral traits of the subalpine herb Ipomopsis sp. in 10 years that differed in precipitation, causing extreme temporal variation in the date of snowmelt in the Colorado Rocky Mountains. The chosen floral traits were under selection by hummingbird and hawkmoth pollinators, with hawkmoth abundance highly variable across years. Selection for flower length showed environmental sensitivity, with stronger selection in years with later snowmelt, as higher water resources can allow translation of pollination success into fitness based on seed production. Selection on corolla width also varied across years, favouring narrower corolla tubes in two unusual years with hawkmoths, and wider corollas in another late snowmelt year. Our results illustrate how changes in climate could alter natural selection even when the primary selective agent is not directly influenced. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  18. Functional mining of transporters using synthetic selections

    DEFF Research Database (Denmark)

    Genee, Hans Jasper; Bali, Anne Pihl; Petersen, Søren Dalsgård

    2016-01-01

    transporters, PnuT, which is widely distributed across multiple bacterial phyla. We demonstrate that with modular replacement of the biosensor, we could expand our method to xanthine and identify xanthine permeases from gut and soil metagenomes. Our results demonstrate how synthetic-biology approaches can......-responsive biosensor systems that enable selective growth of cells only if they encode a ligand-specific importer. We developed such a synthetic selection system for thiamine pyrophosphate and mined soil and gut metagenomes for thiamine-uptake functions. We identified several members of a novel class of thiamine...

  19. Constraint, natural selection, and the evolution of human body form.

    Science.gov (United States)

    Savell, Kristen R R; Auerbach, Benjamin M; Roseman, Charles C

    2016-08-23

    Variation in body form among human groups is structured by a blend of natural selection driven by local climatic conditions and random genetic drift. However, attempts to test ecogeographic hypotheses have not distinguished between adaptive traits (i.e., those that evolved as a result of selection) and those that evolved as a correlated response to selection on other traits (i.e., nonadaptive traits), complicating our understanding of the relationship between climate and morphological distinctions among populations. Here, we use evolutionary quantitative methods to test if traits previously identified as supporting ecogeographic hypotheses were actually adaptive by estimating the force of selection on individual traits needed to drive among-group differentiation. Our results show that not all associations between trait means and latitude were caused by selection acting directly on each individual trait. Although radial and tibial length and biiliac and femoral head breadth show signs of responses to directional selection matching ecogeographic hypotheses, the femur was subject to little or no directional selection despite having shorter values by latitude. Additionally, in contradiction to ecogeographic hypotheses, the humerus was under directional selection for longer values by latitude. Responses to directional selection in the tibia and radius induced a nonadaptive correlated response in the humerus that overwhelmed its own trait-specific response to selection. This result emphasizes that mean differences between groups are not good indicators of which traits are adaptations in the absence of information about covariation among characteristics.

  20. Antiherbivore defenses alter natural selection on plant reproductive traits.

    Science.gov (United States)

    Thompson, Ken A; Johnson, Marc T J

    2016-04-01

    While many studies demonstrate that herbivores alter selection on plant reproductive traits, little is known about whether antiherbivore defenses affect selection on these traits. We hypothesized that antiherbivore defenses could alter selection on reproductive traits by altering trait expression through allocation trade-offs, or by altering interactions with mutualists and/or antagonists. To test our hypothesis, we used white clover, Trifolium repens, which has a Mendelian polymorphism for the production of hydrogen cyanide-a potent antiherbivore defense. We conducted a common garden experiment with 185 clonal families of T. repens that included cyanogenic and acyanogenic genotypes. We quantified resistance to herbivores, and selection on six floral traits and phenology via male and female fitness. Cyanogenesis reduced herbivory but did not alter the expression of reproductive traits through allocation trade-offs. However, the presence of cyanogenic defenses altered natural selection on petal morphology and the number of flowers within inflorescences via female fitness. Herbivory influenced selection on flowers and phenology via female fitness independently of cyanogenesis. Our results demonstrate that both herbivory and antiherbivore defenses alter natural selection on plant reproductive traits. We discuss the significance of these results for understanding how antiherbivore defenses interact with herbivores and pollinators to shape floral evolution. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

  1. A Conceptual Characterization of Online Videos Explaining Natural Selection

    Science.gov (United States)

    Bohlin, Gustav; Göransson, Andreas; Höst, Gunnar E.; Tibell, Lena A. E.

    2017-01-01

    Educational videos on the Internet comprise a vast and highly diverse source of information. Online search engines facilitate access to numerous videos claiming to explain natural selection, but little is known about the degree to which the video content match key evolutionary content identified as important in evolution education research. In…

  2. Selection criteria for forested natural areas in New England, USA

    Science.gov (United States)

    William B. Leak; Mariko Yamasaki; Marie-Louise Smith; David T. Funk

    1994-01-01

    The selection of forested natural areas for research and educational purposes is discussed. Five factors are important: sufficient size; representation of typical communities and sites; documented disturbance histories; acceptable current condition in terms of age, tree size, and successional stage; and administrative feasibility.

  3. The Living Dead: Transformative Experiences in Modelling Natural Selection

    Science.gov (United States)

    Petersen, Morten Rask

    2017-01-01

    This study considers how students change their coherent conceptual understanding of natural selection through a hands-on simulation. The results show that most students change their understanding. In addition, some students also underwent a transformative experience and used their new knowledge in a leisure time activity. These transformative…

  4. Natural selection drives the evolution of ant life cycles.

    Science.gov (United States)

    Wilson, Edward O; Nowak, Martin A

    2014-09-02

    The genetic origin of advanced social organization has long been one of the outstanding problems of evolutionary biology. Here we present an analysis of the major steps in ant evolution, based for the first time, to our knowledge, on combined recent advances in paleontology, phylogeny, and the study of contemporary life histories. We provide evidence of the causal forces of natural selection shaping several key phenomena: (i) the relative lateness and rarity in geological time of the emergence of eusociality in ants and other animal phylads; (ii) the prevalence of monogamy at the time of evolutionary origin; and (iii) the female-biased sex allocation observed in many ant species. We argue that a clear understanding of the evolution of social insects can emerge if, in addition to relatedness-based arguments, we take into account key factors of natural history and study how natural selection acts on alleles that modify social behavior.

  5. Selection of radioactive waste disposal site considering natural processes

    International Nuclear Information System (INIS)

    Nakamura, H.

    1991-01-01

    To dispose the radioactive waste, it is necessary to consider the transfer of material in natural environment. The points of consideration are 1) Long residence time of water 2) Independence of biosphere from the compartment containing the disposal site in the natural hydrologic cycle 3) Dilution with the natural inactive isotope or the same group of elements. Isotope dilution for 129 I and 14 C can be expected by proper selection of the site. 241 Am and 239 Pu will be homogenized into soil or sediment with insoluble elements such as iron and aluminium. For 237 Np and 99 Tc anionic condition is important for the selection. From the point of view of hydrologic cycle, anoxic dead water zone avoiding beneath mountain area is preferable for the disposal site. (author)

  6. Natural selection on immune defense: A field experiment.

    Science.gov (United States)

    Langeloh, Laura; Behrmann-Godel, Jasminca; Seppälä, Otto

    2017-02-01

    Predicting the evolution of phenotypic traits requires an understanding of natural selection on them. Despite its indispensability in the fight against parasites, selection on host immune defense has remained understudied. Theory predicts immune traits to be under stabilizing selection due to associated trade-offs with other fitness-related traits. Empirical studies, however, report mainly positive directional selection. This discrepancy could be caused by low phenotypic variation in the examined individuals and/or variation in host resource level that confounds trade-offs in empirical studies. In a field experiment where we maintained Lymnaea stagnalis snails individually in cages in a lake, we investigated phenotypic selection on two immune defense traits, phenoloxidase (PO)-like activity and antibacterial activity, in hemolymph. We used a diverse laboratory population and manipulated snail resource level by limiting their food supply. For six weeks, we followed immune activity, growth, and two fitness components, survival and fecundity of snails. We found that PO-like activity and growth were under stabilizing selection, while antibacterial activity was under positive directional selection. Selection on immune traits was mainly driven by variation in survival. The form of selection on immune defense apparently depends on the particular trait, possibly due to its importance for countering the present parasite community. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

  7. The insufficient part of abiogenesis theory - natural selection

    Science.gov (United States)

    Ploompuu, Tõnu

    2016-04-01

    Abiogenesis has already been studied for a whole century. There have been studies on the synthesis of precursors of biopolymers, concentration processes and polymerization pathways, sites of initiation of life. Autoreplication has been explained. Protocells have been constructed from abiogenic membranes. But one essential aspect for life - the natural selection - has been marginalized in these investigations. Despite the convincing use of natural selection in biology for one and half century, it has not been used sufficiently in the models of the beginning of life. Pictorially - Darwin's pond model is used without darwinism. This generates an unnecessary interruption on the path for understanding the process. Natural selection is essential in abiogenesis, in the genesis of biological information system. A selection of more collaborative autoreplicate biopolymers and the depolymerisation of others was required. Only natural selection was able to combine biopolymer molecules for life. The primary natural selection can operate only in an environment with variable physical and chemical conditions. The selective agent must constantly fluctuate during a long time span and a large area. Formation of the simplest complex of life needs homeostasis. The best sites for constant fluctuations are littoral areas of oceans. Two very constant fluctuations - waves and tides - occur there. The best conditions for the origin of life were exactly in the end of the Late Heavy Bombardment at temperature nealy 100° C. Earth's surface was then protected against the UV destruction by a thick cloud cover. High evaporation at the hotter parts of shore rocks increased the concentration of the primordial soup and there was excellent selective power by routine water level fluctuations. Because of the water level fluctuations salty ocean water and fresh water from continuous downpours alternated at the littoral zones. In low temperatures the formation of life would be hindered by UV

  8. The quasar luminosity function from a variability-selected sample

    Science.gov (United States)

    Hawkins, M. R. S.; Veron, P.

    1993-01-01

    A sample of quasars is selected from a 10-yr sequence of 30 UK Schmidt plates. Luminosity functions are derived in several redshift intervals, which in each case show a featureless power-law rise towards low luminosities. There is no sign of the 'break' found in the recent UVX sample of Boyle et al. It is suggested that reasons for the disagreement are connected with biases in the selection of the UVX sample. The question of the nature of quasar evolution appears to be still unresolved.

  9. Naturally acidified habitat selects for ocean acidification-tolerant mussels.

    Science.gov (United States)

    Thomsen, Jörn; Stapp, Laura S; Haynert, Kristin; Schade, Hanna; Danelli, Maria; Lannig, Gisela; Wegner, K Mathias; Melzner, Frank

    2017-04-01

    Ocean acidification severely affects bivalves, especially their larval stages. Consequently, the fate of this ecologically and economically important group depends on the capacity and rate of evolutionary adaptation to altered ocean carbonate chemistry. We document successful settlement of wild mussel larvae ( Mytilus edulis ) in a periodically CO 2 -enriched habitat. The larval fitness of the population originating from the CO 2 -enriched habitat was compared to the response of a population from a nonenriched habitat in a common garden experiment. The high CO 2 -adapted population showed higher fitness under elevated P co 2 (partial pressure of CO 2 ) than the non-adapted cohort, demonstrating, for the first time, an evolutionary response of a natural mussel population to ocean acidification. To assess the rate of adaptation, we performed a selection experiment over three generations. CO 2 tolerance differed substantially between the families within the F 1 generation, and survival was drastically decreased in the highest, yet realistic, P co 2 treatment. Selection of CO 2 -tolerant F 1 animals resulted in higher calcification performance of F 2 larvae during early shell formation but did not improve overall survival. Our results thus reveal significant short-term selective responses of traits directly affected by ocean acidification and long-term adaptation potential in a key bivalve species. Because immediate response to selection did not directly translate into increased fitness, multigenerational studies need to take into consideration the multivariate nature of selection acting in natural habitats. Combinations of short-term selection with long-term adaptation in populations from CO 2 -enriched versus nonenriched natural habitats represent promising approaches for estimating adaptive potential of organisms facing global change.

  10. Naturally selecting solutions: the use of genetic algorithms in bioinformatics.

    Science.gov (United States)

    Manning, Timmy; Sleator, Roy D; Walsh, Paul

    2013-01-01

    For decades, computer scientists have looked to nature for biologically inspired solutions to computational problems; ranging from robotic control to scheduling optimization. Paradoxically, as we move deeper into the post-genomics era, the reverse is occurring, as biologists and bioinformaticians look to computational techniques, to solve a variety of biological problems. One of the most common biologically inspired techniques are genetic algorithms (GAs), which take the Darwinian concept of natural selection as the driving force behind systems for solving real world problems, including those in the bioinformatics domain. Herein, we provide an overview of genetic algorithms and survey some of the most recent applications of this approach to bioinformatics based problems.

  11. Natural fibre selection for composite eco-design

    DEFF Research Database (Denmark)

    Corona, Andrea; Madsen, Bo; Hauschild, Michael Zwicky

    2016-01-01

    Natural fibre composites (NFC) are gaining interest in manufacturing because they address some of the environmental problems of traditional composites: use of non-renewable resources, and large impacts related to their production and disposal. Since natural fibres are not yet optimized...... for composite production, it is crucial to identify the most appropriate applications, and determine the optimal fibre/matrix ratio. A methodology is proposed for early-stage decisions support on selection of bio-composite materials. Results help identify the application with the largest reduction...

  12. Adverse Selection Models with Three States of Nature

    Directory of Open Access Journals (Sweden)

    Daniela MARINESCU

    2011-02-01

    Full Text Available In the paper we analyze an adverse selection model with three states of nature, where both the Principal and the Agent are risk neutral. When solving the model, we use the informational rents and the efforts as variables. We derive the optimal contract in the situation of asymmetric information. The paper ends with the characteristics of the optimal contract and the main conclusions of the model.

  13. Natural Selection and Genetic Diversity in the Butterfly Heliconius melpomene.

    Science.gov (United States)

    Martin, Simon H; Möst, Markus; Palmer, William J; Salazar, Camilo; McMillan, W Owen; Jiggins, Francis M; Jiggins, Chris D

    2016-05-01

    A combination of selective and neutral evolutionary forces shape patterns of genetic diversity in nature. Among the insects, most previous analyses of the roles of drift and selection in shaping variation across the genome have focused on the genus Drosophila A more complete understanding of these forces will come from analyzing other taxa that differ in population demography and other aspects of biology. We have analyzed diversity and signatures of selection in the neotropical Heliconius butterflies using resequenced genomes from 58 wild-caught individuals of Heliconius melpomene and another 21 resequenced genomes representing 11 related species. By comparing intraspecific diversity and interspecific divergence, we estimate that 31% of amino acid substitutions between Heliconius species are adaptive. Diversity at putatively neutral sites is negatively correlated with the local density of coding sites as well as nonsynonymous substitutions and positively correlated with recombination rate, indicating widespread linked selection. This process also manifests in significantly reduced diversity on longer chromosomes, consistent with lower recombination rates. Although hitchhiking around beneficial nonsynonymous mutations has significantly shaped genetic variation in H. melpomene, evidence for strong selective sweeps is limited overall. We did however identify two regions where distinct haplotypes have swept in different populations, leading to increased population differentiation. On the whole, our study suggests that positive selection is less pervasive in these butterflies as compared to fruit flies, a fact that curiously results in very similar levels of neutral diversity in these very different insects. Copyright © 2016 by the Genetics Society of America.

  14. Substitution rate and natural selection in parvovirus B19

    Science.gov (United States)

    Stamenković, Gorana G.; Ćirković, Valentina S.; Šiljić, Marina M.; Blagojević, Jelena V.; Knežević, Aleksandra M.; Joksić, Ivana D.; Stanojević, Maja P.

    2016-01-01

    The aim of this study was to estimate substitution rate and imprints of natural selection on parvovirus B19 genotype 1. Studied datasets included 137 near complete coding B19 genomes (positions 665 to 4851) for phylogenetic and substitution rate analysis and 146 and 214 partial genomes for selection analyses in open reading frames ORF1 and ORF2, respectively, collected 1973–2012 and including 9 newly sequenced isolates from Serbia. Phylogenetic clustering assigned majority of studied isolates to G1A. Nucleotide substitution rate for total coding DNA was 1.03 (0.6–1.27) x 10−4 substitutions/site/year, with higher values for analyzed genome partitions. In spite of the highest evolutionary rate, VP2 codons were found to be under purifying selection with rare episodic positive selection, whereas codons under diversifying selection were found in the unique part of VP1, known to contain B19 immune epitopes important in persistent infection. Analyses of overlapping gene regions identified nucleotide positions under opposite selective pressure in different ORFs, suggesting complex evolutionary mechanisms of nucleotide changes in B19 viral genomes. PMID:27775080

  15. Developing Conceptual Understanding of Natural Selection: The Role of Interest, Efficacy, and Basic Prior Knowledge

    Science.gov (United States)

    Linnenbrink-Garcia, Lisa; Pugh, Kevin J.; Koskey, Kristin L. K.; Stewart, Victoria C.

    2012-01-01

    Changes in high school students' (n = 94) conceptions of natural selection were examined as a function of motivational beliefs (individual interest, academic self-efficacy), basic prior knowledge, and gender across three assessments (pre, post, follow-up). Results from variable-centered analyses suggested that these variables had relatively little…

  16. Natural selection and algorithmic design of mRNA.

    Science.gov (United States)

    Cohen, Barry; Skiena, Steven

    2003-01-01

    Messenger RNA (mRNA) sequences serve as templates for proteins according to the triplet code, in which each of the 4(3) = 64 different codons (sequences of three consecutive nucleotide bases) in RNA either terminate transcription or map to one of the 20 different amino acids (or residues) which build up proteins. Because there are more codons than residues, there is inherent redundancy in the coding. Certain residues (e.g., tryptophan) have only a single corresponding codon, while other residues (e.g., arginine) have as many as six corresponding codons. This freedom implies that the number of possible RNA sequences coding for a given protein grows exponentially in the length of the protein. Thus nature has wide latitude to select among mRNA sequences which are informationally equivalent, but structurally and energetically divergent. In this paper, we explore how nature takes advantage of this freedom and how to algorithmically design structures more energetically favorable than have been built through natural selection. In particular: (1) Natural Selection--we perform the first large-scale computational experiment comparing the stability of mRNA sequences from a variety of organisms to random synonymous sequences which respect the codon preferences of the organism. This experiment was conducted on over 27,000 sequences from 34 microbial species with 36 genomic structures. We provide evidence that in all genomic structures highly stable sequences are disproportionately abundant, and in 19 of 36 cases highly unstable sequences are disproportionately abundant. This suggests that the stability of mRNA sequences is subject to natural selection. (2) Artificial Selection--motivated by these biological results, we examine the algorithmic problem of designing the most stable and unstable mRNA sequences which code for a target protein. We give a polynomial-time dynamic programming solution to the most stable sequence problem (MSSP), which is asymptotically no more complex

  17. Natural Selection in Virulence Genes of Francisella tularensis.

    Science.gov (United States)

    Gunnell, Mark K; Robison, Richard A; Adams, Byron J

    2016-06-01

    A fundamental tenet of evolution is that alleles that are under negative selection are often deleterious and confer no evolutionary advantage. Negatively selected alleles are removed from the gene pool and are eventually extinguished from the population. Conversely, alleles under positive selection do confer an evolutionary advantage and lead to an increase in the overall fitness of the organism. These alleles increase in frequency until they eventually become fixed in the population. Francisella tularensis is a zoonotic pathogen and a potential biothreat agent. The most virulent type of F. tularensis, Type A, is distributed across North America with Type A.I occurring mainly in the east and Type A.II appearing mainly in the west. F. tularensis is thought to be a genome in decay (losing genes) because of the relatively large number of pseudogenes present in its genome. We hypothesized that the observed frequency of gene loss/pseudogenes may be an artifact of evolution in response to a changing environment, and that genes involved in virulence should be under strong positive selection. To test this hypothesis, we sequenced and compared whole genomes of Type A.I and A.II isolates. We analyzed a subset of virulence and housekeeping genes from several F. tularensis subspecies genomes to ascertain the presence and extent of positive selection. Eleven previously identified virulence genes were screened for positive selection along with 10 housekeeping genes. Analyses of selection yielded one housekeeping gene and 7 virulence genes which showed significant evidence of positive selection at loci implicated in cell surface structures and membrane proteins, metabolism and biosynthesis, transcription, translation and cell separation, and substrate binding and transport. Our results suggest that while the loss of functional genes through disuse could be accelerated by negative selection, the genome decay in Francisella could also be the byproduct of adaptive evolution

  18. Using David Lack's Observations of Finch Beak Size to Teach Natural Selection & the Nature of Science

    Science.gov (United States)

    Bierema, Andrea M.-K.; Rudge, David W.

    2014-01-01

    One of the key aspects of natural selection is competition, yet the concept of competition is not necessarily emphasized in explanations of natural selection. Because of this, we developed an activity for our class that focuses on competition and provides an example of the effects of competition on natural selection. This hands-on activity models…

  19. Determining the Effect of Natural Selection on Linked Neutral Divergence across Species.

    Science.gov (United States)

    Phung, Tanya N; Huber, Christian D; Lohmueller, Kirk E

    2016-08-01

    A major goal in evolutionary biology is to understand how natural selection has shaped patterns of genetic variation across genomes. Studies in a variety of species have shown that neutral genetic diversity (intra-species differences) has been reduced at sites linked to those under direct selection. However, the effect of linked selection on neutral sequence divergence (inter-species differences) remains ambiguous. While empirical studies have reported correlations between divergence and recombination, which is interpreted as evidence for natural selection reducing linked neutral divergence, theory argues otherwise, especially for species that have diverged long ago. Here we address these outstanding issues by examining whether natural selection can affect divergence between both closely and distantly related species. We show that neutral divergence between closely related species (e.g. human-primate) is negatively correlated with functional content and positively correlated with human recombination rate. We also find that neutral divergence between distantly related species (e.g. human-rodent) is negatively correlated with functional content and positively correlated with estimates of background selection from primates. These patterns persist after accounting for the confounding factors of hypermutable CpG sites, GC content, and biased gene conversion. Coalescent models indicate that even when the contribution of ancestral polymorphism to divergence is small, background selection in the ancestral population can still explain a large proportion of the variance in divergence across the genome, generating the observed correlations. Our findings reveal that, contrary to previous intuition, natural selection can indirectly affect linked neutral divergence between both closely and distantly related species. Though we cannot formally exclude the possibility that the direct effects of purifying selection drive some of these patterns, such a scenario would be possible only

  20. EFFECT OF NATURAL PLANT EXTRACTS ON PORCINE OVARIAN FUNCTIONS

    Directory of Open Access Journals (Sweden)

    Attila Kádasi

    2015-02-01

    Full Text Available This report provides information about the impact of chosen natural plant extracts on basic ovarian functions. This article summarizes our results concerning the effect of selected plant extracts on proliferation, apoptosis and hormone secretion – release of progesterone (P4, testosterone (T and leptin (L on porcine granulosa cells (GC, We analyzed effects of ginkgo (GB, rooibos (RB, flaxseed (FL, green tea polyphenols (GTPP, green tea - epigallocatechin-3-gallate (EGCG, resveratrol (RSV and curcumin (CURC (0; 1; 10 and 100 μg.ml-1 on markers of proliferation, apoptosis and secretory activity of porcine ovarian granulosa cells by using immunocytochemistry and EIA. It was demonstrated, that all these natural plants and plant molecules inhibited the accumulation of proliferation-related peptide (PCNA and apoptosis-associated peptide (Bax in cultured. Furthermore, it was observed that natural plant extracts altered progesterone, testosterone and leptin release in porcine ovarian cells. It is concluded, that GB, RB, FL, RSV, CURC, GTPP and EGCG can directly affect ovarian cells and therefore they could potentially influence ovarian functions.

  1. Antagonistic natural and sexual selection on wing shape in a scrambling damselfly.

    Science.gov (United States)

    Outomuro, David; Söderquist, Linus; Nilsson-Örtman, Viktor; Cortázar-Chinarro, María; Lundgren, Cecilia; Johansson, Frank

    2016-07-01

    Wings are a key trait underlying the evolutionary success of birds, bats, and insects. For over a century, researchers have studied the form and function of wings to understand the determinants of flight performance. However, to understand the evolution of flight, we must comprehend not only how morphology affects performance, but also how morphology and performance affect fitness. Natural and sexual selection can either reinforce or oppose each other, but their role in flight evolution remains poorly understood. Here, we show that wing shape is under antagonistic selection with regard to sexual and natural selection in a scrambling damselfly. In a field setting, natural selection (survival) favored individuals with long and slender forewings and short and broad hindwings. In contrast, sexual selection (mating success) favored individuals with short and broad forewings and narrow-based hindwings. Both types of selection favored individuals of intermediate size. These results suggest that individuals face a trade-off between flight energetics and maneuverability and demonstrate how natural and sexual selection can operate in similar directions for some wing traits, that is, wing size, but antagonistically for others, that is, wing shape. Furthermore, they highlight the need to study flight evolution within the context of species' mating systems and mating behaviors. © 2016 The Author(s).

  2. Deficient natural killer cell function in preeclampsia

    Energy Technology Data Exchange (ETDEWEB)

    Alanen, A.; Lassila, O.

    1982-11-01

    Natural killer cell activity of peripheral blood lymphocytes was measured against K-562 target cells with a 4-hour /sup 51/Cr release assay in 15 primigravid women with preeclamptic symptoms. Nineteen primigravid women with an uncomplicated pregnancy and 18 nonpregnant women served as controls. The natural killer cell activity of preeclamptic women was observed to be significantly lower than that of both control groups. Natural killer cells in preeclamptic women responded normally to augmentation caused by interferon. These findings give further evidence for the participation of the maternal immune system in this pregnancy disorder.

  3. Deficient natural killer cell function in preeclampsia

    International Nuclear Information System (INIS)

    Alanen, A.; Lassila, O.

    1982-01-01

    Natural killer cell activity of peripheral blood lymphocytes was measured against K-562 target cells with a 4-hour 51 Cr release assay in 15 primigravid women with preeclamptic symptoms. Nineteen primigravid women with an uncomplicated pregnancy and 18 nonpregnant women served as controls. The natural killer cell activity of preeclamptic women was observed to be significantly lower than that of both control groups. Natural killer cells in preeclamptic women responded normally to augmentation caused by interferon. These findings give further evidence for the participation of the maternal immune system in this pregnancy disorder

  4. Holographic memories with encryption-selectable function

    Science.gov (United States)

    Su, Wei-Chia; Lee, Xuan-Hao

    2006-03-01

    Volume holographic storage has received increasing attention owing to its potential high storage capacity and access rate. In the meanwhile, encrypted holographic memory using random phase encoding technique is attractive for an optical community due to growing demand for protection of information. In this paper, encryption-selectable holographic storage algorithms in LiNbO 3 using angular multiplexing are proposed and demonstrated. Encryption-selectable holographic memory is an advance concept of security storage for content protection. It offers more flexibility to encrypt the data or not optionally during the recording processes. In our system design, the function of encryption and non-encryption storage is switched by a random phase pattern and a uniform phase pattern. Based on a 90-degree geometry, the input patterns including the encryption and non-encryption storage are stored via angular multiplexing with reference plane waves at different incident angles. Image is encrypted optionally by sliding the ground glass into one of the recording waves or removing it away in each exposure. The ground glass is a key for encryption. Besides, it is also an important key available for authorized user to decrypt the encrypted information.

  5. The natural selection of metabolism explains curvature in allometric scaling

    OpenAIRE

    Witting, Lars

    2016-01-01

    I simulate the evolution of metabolism and mass to explain the curvature in the metabolic allometry for placental and marsupial mammals. I assume that the release of inter-specific competition by the extinction of dinosaurs 65 million years ago made it possible for each clade to diversity into a multitude of species across a wide range of niches. The natural selection of metabolism and mass was then fitted to explain the maximum observed body masses over time, as well as the current inter-spe...

  6. Natural Selection Reduced Diversity on Human Y Chromosomes

    Science.gov (United States)

    Wilson Sayres, Melissa A.; Lohmueller, Kirk E.; Nielsen, Rasmus

    2014-01-01

    The human Y chromosome exhibits surprisingly low levels of genetic diversity. This could result from neutral processes if the effective population size of males is reduced relative to females due to a higher variance in the number of offspring from males than from females. Alternatively, selection acting on new mutations, and affecting linked neutral sites, could reduce variability on the Y chromosome. Here, using genome-wide analyses of X, Y, autosomal and mitochondrial DNA, in combination with extensive population genetic simulations, we show that low observed Y chromosome variability is not consistent with a purely neutral model. Instead, we show that models of purifying selection are consistent with observed Y diversity. Further, the number of sites estimated to be under purifying selection greatly exceeds the number of Y-linked coding sites, suggesting the importance of the highly repetitive ampliconic regions. While we show that purifying selection removing deleterious mutations can explain the low diversity on the Y chromosome, we cannot exclude the possibility that positive selection acting on beneficial mutations could have also reduced diversity in linked neutral regions, and may have contributed to lowering human Y chromosome diversity. Because the functional significance of the ampliconic regions is poorly understood, our findings should motivate future research in this area. PMID:24415951

  7. Defining mental disorder. Exploring the 'natural function' approach

    Directory of Open Access Journals (Sweden)

    Varga Somogy

    2011-01-01

    Full Text Available Abstract Due to several socio-political factors, to many psychiatrists only a strictly objective definition of mental disorder, free of value components, seems really acceptable. In this paper, I will explore a variant of such an objectivist approach to defining metal disorder, natural function objectivism. Proponents of this approach make recourse to the notion of natural function in order to reach a value-free definition of mental disorder. The exploration of Christopher Boorse's 'biostatistical' account of natural function (1 will be followed an investigation of the 'hybrid naturalism' approach to natural functions by Jerome Wakefield (2. In the third part, I will explore two proposals that call into question the whole attempt to define mental disorder (3. I will conclude that while 'natural function objectivism' accounts fail to provide the backdrop for a reliable definition of mental disorder, there is no compelling reason to conclude that a definition cannot be achieved.

  8. Defining mental disorder. Exploring the 'natural function' approach.

    Science.gov (United States)

    Varga, Somogy

    2011-01-21

    Due to several socio-political factors, to many psychiatrists only a strictly objective definition of mental disorder, free of value components, seems really acceptable. In this paper, I will explore a variant of such an objectivist approach to defining metal disorder, natural function objectivism. Proponents of this approach make recourse to the notion of natural function in order to reach a value-free definition of mental disorder. The exploration of Christopher Boorse's 'biostatistical' account of natural function (1) will be followed an investigation of the 'hybrid naturalism' approach to natural functions by Jerome Wakefield (2). In the third part, I will explore two proposals that call into question the whole attempt to define mental disorder (3). I will conclude that while 'natural function objectivism' accounts fail to provide the backdrop for a reliable definition of mental disorder, there is no compelling reason to conclude that a definition cannot be achieved.

  9. Effects of environmental changes on natural selection active on human polygenic traits.

    Science.gov (United States)

    Ulizzi, L

    1993-06-01

    During the last century, industrialized countries experienced such an improvement in socioeconomic conditions and in sanitation that it is likely that the selective forces active on human metric traits have been modified. Perinatal mortality as a function of birth weight is one of the clearest examples of natural selection in humans. Here, trends over time of stabilizing and directional selection associated with birth weight have been analyzed in Japan from 1969 to 1989. The population of newborns has been subdivided according to gestational age, which is one of the main covariates of birth weight. The results show that in full-term babies both stabilizing and directional selection are coming to an end, whereas in babies born after 8 months of gestation these selective forces are still active, even if at much lower levels than in the past. The peculiar results found in the 7-month-gestation population are probably due to grossly abnormal cases of immaturity.

  10. On the nature and function of organizers.

    Science.gov (United States)

    Martinez Arias, Alfonso; Steventon, Ben

    2018-03-09

    Organizers, which comprise groups of cells with the ability to instruct adjacent cells into specific states, represent a key principle in developmental biology. The concept was first introduced by Spemann and Mangold, who showed that there is a cellular population in the newt embryo that elicits the development of a secondary axis from adjacent cells. Similar experiments in chicken and rabbit embryos subsequently revealed groups of cells with similar instructive potential. In birds and mammals, organizer activity is often associated with a structure known as the node, which has thus been considered a functional homologue of Spemann's organizer. Here, we take an in-depth look at the structure and function of organizers across species and note that, whereas the amphibian organizer is a contingent collection of elements, each performing a specific function, the elements of organizers in other species are dispersed in time and space. This observation urges us to reconsider the universality and meaning of the organizer concept. © 2018. Published by The Company of Biologists Ltd.

  11. Mosquito management in the face of natural selection

    KAUST Repository

    Agusto, Folashade B.

    2012-09-01

    The sterile insect technique (SIT) is an appealing method for managing mosquito populations while avoiding the environmental and social costs associated with more traditional control strategies like insecticide application. Success of SIT, however, hinges on sterile males being able to compete for females. As a result, heavy and/or continued use of SIT could potentially diminish its efficacy if prolonged treatments result in selection for female preference against sterile males. In this paper we extend a general differential equation model of mosquito dynamics to consider the role of female choosiness in determining the long-term usefulness of SIT as a management option. We then apply optimal control theory to our model and show how natural selection for female choosiness fundamentally alters management strategies. Our study calls into question the benefits associated with developing SIT as a management strategy, and suggests that effort should be spent studying female mate choice in order to determine its relative importance and how likely it is to impact SIT treatment goals. © 2012.

  12. Complex and changing patterns of natural selection explain the evolution of the human hip.

    Science.gov (United States)

    Grabowski, Mark; Roseman, Charles C

    2015-08-01

    Causal explanations for the dramatic changes that occurred during the evolution of the human hip focus largely on selection for bipedal function and locomotor efficiency. These hypotheses rest on two critical assumptions. The first-that these anatomical changes served functional roles in bipedalism-has been supported in numerous analyses showing how postcranial changes likely affected locomotion. The second-that morphological changes that did play functional roles in bipedalism were the result of selection for that behavior-has not been previously explored and represents a major gap in our understanding of hominin hip evolution. Here we use evolutionary quantitative genetic models to test the hypothesis that strong directional selection on many individual aspects of morphology was responsible for the large differences observed across a sample of fossil hominin hips spanning the Plio-Pleistocene. Our approach uses covariance among traits and the differences between relatively complete fossils to estimate the net selection pressures that drove the major transitions in hominin hip evolution. Our findings show a complex and changing pattern of natural selection drove hominin hip evolution, and that many, but not all, traits hypothesized to play functional roles in bipedalism evolved as a direct result of natural selection. While the rate of evolutionary change for all transitions explored here does not exceed the amount expected if evolution was occurring solely through neutral processes, it was far above rates of evolution for morphological traits in other mammalian groups. Given that stasis is the norm in the mammalian fossil record, our results suggest that large shifts in the adaptive landscape drove hominin evolution. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Natural Aphrodisiacs-A Review of Selected Sexual Enhancers.

    Science.gov (United States)

    West, Elizabeth; Krychman, Michael

    2015-10-01

    The Food and Drug Administration defines an aphrodisiac drug product as "any product that bears labeling claims that it will arouse or increase sexual desire, or that it will improve sexual performance." Presently, there are no approved medications for the treatment of lowered desire for women, and many opt for "natural" products. The aim of this article was to review the most popular and currently used aphrodisiac products marketed in the United States. The safety and efficacy of animal- and plant-based aphrodisiacs, vitamins and minerals, and popular over-the-counter combination supplements have been reviewed. An English PubMed literature search was performed using the key words "sexuality," "sex," "aphrodisiac," and "sexual enhancer." Approximately 50 articles were reviewed by the authors. The authors used relevant case series, case-controlled, and randomized clinical trial data. Products were evaluated based on the quality of research, and their known efficacy and safety considerations. Products with low risk and potential benefit for sexual response based on prior research studies were highlighted. Research has demonstrated that the risks of yohimbine, Spanish fly, mad honey, and Bufo toad may outweigh any benefit, and these products should be avoided. Other products, such as Maca, Tribulus, Ginkgo, and ginseng, have limited but emerging data. Randomized clinical trial data are often lacking, but future research should be performed to further elucidate the efficacy and safety of these products. Future randomized clinical trials are warranted before health care practitioners can recommend most aphrodisiac products. There remain some medical concerns with drug interactions, purity, reliability, and safety. West E and Krychman M. Natural aphrodisiacs-A review of selected sexual enhancers.. Copyright © 2015 International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.

  14. Development and Validation of the Conceptual Assessment of Natural Selection (CANS)

    Science.gov (United States)

    Kalinowski, Steven T.; Leonard, Mary J.; Taper, Mark L.

    2016-01-01

    We developed and validated the Conceptual Assessment of Natural Selection (CANS), a multiple-choice test designed to assess how well college students understand the central principles of natural selection. The expert panel that reviewed the CANS concluded its questions were relevant to natural selection and generally did a good job sampling the…

  15. Contributions of natural and sexual selection to the evolution of premating reproductive isolation: a research agenda.

    Science.gov (United States)

    Safran, Rebecca J; Scordato, Elizabeth S C; Symes, Laurel B; Rodríguez, Rafael L; Mendelson, Tamra C

    2013-11-01

    Speciation by divergent natural selection is well supported. However, the role of sexual selection in speciation is less well understood due to disagreement about whether sexual selection is a mechanism of evolution separate from natural selection, as well as confusion about various models and tests of sexual selection. Here, we outline how sexual selection and natural selection are different mechanisms of evolutionary change, and suggest that this distinction is critical when analyzing the role of sexual selection in speciation. Furthermore, we clarify models of sexual selection with respect to their interaction with ecology and natural selection. In doing so, we outline a research agenda for testing hypotheses about the relative significance of divergent sexual and natural selection in the evolution of reproductive isolation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Evolution and natural selection: learning by playing and reflecting

    Directory of Open Access Journals (Sweden)

    David Herrero

    2014-01-01

    Full Text Available Scientific literacy is more than the simple reproduction of traditional school science knowledge and requires a set of skills, among them identifying scientific issues, explaining phenomena scientifically and using scientific evidence. Several studies have indicated that playing computer games in the classroom can support the development of students’ conceptual understanding about scientific phenomena and theories. Our paper presents a research study where the role of the video game Spore as a learning tool was analysed in a Biology class. An ethnographical perspective served as the framework for the organization and development of a workshop comprised of five sessions with 22 4th grade students, and their Biology teacher. The results show that this video game could become an interesting learning tool to improve students’ understanding of evolution and natural selection. The students could combine their previous knowledge with the academic knowledge obtained though the simulation presented by the video game. To sum up, an attempt has been made to give some empirical guidance about effective approaches to the utilisation of games in classrooms, additionally paying attention to a number of concerns related to the effectiveness of video games as learning tools.

  17. Incipient balancing selection through adaptive loss of aquaporins in natural Saccharomyces cerevisiae populations.

    Directory of Open Access Journals (Sweden)

    Jessica L Will

    2010-04-01

    Full Text Available A major goal in evolutionary biology is to understand how adaptive evolution has influenced natural variation, but identifying loci subject to positive selection has been a challenge. Here we present the adaptive loss of a pair of paralogous genes in specific Saccharomyces cerevisiae subpopulations. We mapped natural variation in freeze-thaw tolerance to two water transporters, AQY1 and AQY2, previously implicated in freeze-thaw survival. However, whereas freeze-thaw-tolerant strains harbor functional aquaporin genes, the set of sensitive strains lost aquaporin function at least 6 independent times. Several genomic signatures at AQY1 and/or AQY2 reveal low variation surrounding these loci within strains of the same haplotype, but high variation between strain groups. This is consistent with recent adaptive loss of aquaporins in subgroups of strains, leading to incipient balancing selection. We show that, although aquaporins are critical for surviving freeze-thaw stress, loss of both genes provides a major fitness advantage on high-sugar substrates common to many strains' natural niche. Strikingly, strains with non-functional alleles have also lost the ancestral requirement for aquaporins during spore formation. Thus, the antagonistic effect of aquaporin function-providing an advantage in freeze-thaw tolerance but a fitness defect for growth in high-sugar environments-contributes to the maintenance of both functional and nonfunctional alleles in S. cerevisiae. This work also shows that gene loss through multiple missense and nonsense mutations, hallmarks of pseudogenization presumed to emerge after loss of constraint, can arise through positive selection.

  18. Incipient balancing selection through adaptive loss of aquaporins in natural Saccharomyces cerevisiae populations.

    Science.gov (United States)

    Will, Jessica L; Kim, Hyun Seok; Clarke, Jessica; Painter, John C; Fay, Justin C; Gasch, Audrey P

    2010-04-01

    A major goal in evolutionary biology is to understand how adaptive evolution has influenced natural variation, but identifying loci subject to positive selection has been a challenge. Here we present the adaptive loss of a pair of paralogous genes in specific Saccharomyces cerevisiae subpopulations. We mapped natural variation in freeze-thaw tolerance to two water transporters, AQY1 and AQY2, previously implicated in freeze-thaw survival. However, whereas freeze-thaw-tolerant strains harbor functional aquaporin genes, the set of sensitive strains lost aquaporin function at least 6 independent times. Several genomic signatures at AQY1 and/or AQY2 reveal low variation surrounding these loci within strains of the same haplotype, but high variation between strain groups. This is consistent with recent adaptive loss of aquaporins in subgroups of strains, leading to incipient balancing selection. We show that, although aquaporins are critical for surviving freeze-thaw stress, loss of both genes provides a major fitness advantage on high-sugar substrates common to many strains' natural niche. Strikingly, strains with non-functional alleles have also lost the ancestral requirement for aquaporins during spore formation. Thus, the antagonistic effect of aquaporin function-providing an advantage in freeze-thaw tolerance but a fitness defect for growth in high-sugar environments-contributes to the maintenance of both functional and nonfunctional alleles in S. cerevisiae. This work also shows that gene loss through multiple missense and nonsense mutations, hallmarks of pseudogenization presumed to emerge after loss of constraint, can arise through positive selection.

  19. Spatially Selective Functionalization of Conducting Polymers by "Electroclick" Chemistry

    DEFF Research Database (Denmark)

    Hansen, Thomas Steen; Daugaard, Anders Egede; Hvilsted, Søren

    2009-01-01

    Conducting polymer microelectrodes can electrochemically generate the catalyst required for their own functionalization by "click chemistry" with high spatial resolution. Interdigitated microelectrodes prepared from an azide-containing conducting polymer are selectively functionalized in sequence...

  20. Human fertility, molecular genetics, and natural selection in modern societies.

    Directory of Open Access Journals (Sweden)

    Felix C Tropf

    Full Text Available Research on genetic influences on human fertility outcomes such as number of children ever born (NEB or the age at first childbirth (AFB has been solely based on twin and family-designs that suffer from problematic assumptions and practical limitations. The current study exploits recent advances in the field of molecular genetics by applying the genomic-relationship-matrix based restricted maximum likelihood (GREML methods to quantify for the first time the extent to which common genetic variants influence the NEB and the AFB of women. Using data from the UK and the Netherlands (N = 6,758, results show significant additive genetic effects on both traits explaining 10% (SE = 5 of the variance in the NEB and 15% (SE = 4 in the AFB. We further find a significant negative genetic correlation between AFB and NEB in the pooled sample of -0.62 (SE = 0.27, p-value = 0.02. This finding implies that individuals with genetic predispositions for an earlier AFB had a reproductive advantage and that natural selection operated not only in historical, but also in contemporary populations. The observed postponement in the AFB across the past century in Europe contrasts with these findings, suggesting an evolutionary override by environmental effects and underscoring that evolutionary predictions in modern human societies are not straight forward. It emphasizes the necessity for an integrative research design from the fields of genetics and social sciences in order to understand and predict fertility outcomes. Finally, our results suggest that we may be able to find genetic variants associated with human fertility when conducting GWAS-meta analyses with sufficient sample size.

  1. How can we estimate natural selection on endocrine traits? Lessons from evolutionary biology.

    Science.gov (United States)

    Bonier, Frances; Martin, Paul R

    2016-11-30

    An evolutionary perspective can enrich almost any endeavour in biology, providing a deeper understanding of the variation we see in nature. To this end, evolutionary endocrinologists seek to describe the fitness consequences of variation in endocrine traits. Much of the recent work in our field, however, follows a flawed approach to the study of how selection shapes endocrine traits. Briefly, this approach relies on among-individual correlations between endocrine phenotypes (often circulating hormone levels) and fitness metrics to estimate selection on those endocrine traits. Adaptive plasticity in both endocrine and fitness-related traits can drive these correlations, generating patterns that do not accurately reflect natural selection. We illustrate why this approach to studying selection on endocrine traits is problematic, referring to work from evolutionary biologists who, decades ago, described this problem as it relates to a variety of other plastic traits. We extend these arguments to evolutionary endocrinology, where the likelihood that this flaw generates bias in estimates of selection is unusually high due to the exceptional responsiveness of hormones to environmental conditions, and their function to induce adaptive life-history responses to environmental variation. We end with a review of productive approaches for investigating the fitness consequences of variation in endocrine traits that we expect will generate exciting advances in our understanding of endocrine system evolution. © 2016 The Author(s).

  2. Herbivores modify selection on plant functional traits in a temperate rainforest understory.

    Science.gov (United States)

    Salgado-Luarte, Cristian; Gianoli, Ernesto

    2012-08-01

    There is limited evidence regarding the adaptive value of plant functional traits in contrasting light environments. It has been suggested that changes in these traits in response to light availability can increase herbivore susceptibility. We tested the adaptive value of plant functional traits linked with carbon gain in contrasting light environments and also evaluated whether herbivores can modify selection on these traits in each light environment. In a temperate rainforest, we examined phenotypic selection on functional traits in seedlings of the pioneer tree Aristotelia chilensis growing in sun (canopy gap) and shade (forest understory) and subjected to either natural herbivory or herbivore exclusion. We found differential selection on functional traits depending on light environment. In sun, there was positive directional selection on photosynthetic rate and relative growth rate (RGR), indicating that selection favors competitive ability in a high-resource environment. Seedlings with high specific leaf area (SLA) and intermediate RGR were selected in shade, suggesting that light capture and conservative resource use are favored in the understory. Herbivores reduced the strength of positive directional selection acting on SLA in shade. We provide the first demonstration that natural herbivory rates can change the strength of selection on plant ecophysiological traits, that is, attributes whose main function is resource uptake. Research addressing the evolution of shade tolerance should incorporate the selective role of herbivores.

  3. Functional connectivity of parietal cortex during temporal selective attention.

    Science.gov (United States)

    Tyler, Sarah C; Dasgupta, Samhita; Agosta, Sara; Battelli, Lorella; Grossman, Emily D

    2015-04-01

    Perception of natural experiences requires allocation of attention towards features, objects, and events that are moving and changing over time. This allocation of attention is controlled by large-scale brain networks that, when damaged, cause widespread cognitive deficits. In particular, damage to ventral parietal cortex (right lateralized TPJ, STS, supramarginal and angular gyri) is associated with failures to selectively attend to and isolate features embedded within rapidly changing visual sequences (Battelli, Pascual-Leone, & Cavanagh, 2007; Husain, Shapiro, Martin, & Kennard, 1997). In this study, we used fMRI to investigate the neural activity and functional connectivity of intact parietal cortex while typical subjects judged the relative onsets and offsets of rapidly flickering tokens (a phase discrimination task in which right parietal patients are impaired). We found two regions in parietal cortex correlated with task performance: a bilateral posterior TPJ (pTPJ) and an anterior right-lateralized TPJ (R aTPJ). Both regions were deactivated when subjects engaged in the task but showed different patterns of functional connectivity. The bilateral pTPJ was strongly connected to nodes within the default mode network (DMN) and the R aTPJ was connected to the attention network. Accurate phase discriminations were associated with increased functional correlations between sensory cortex (hMT+) and the bilateral pTPJ, whereas accuracy on a control task was associated with yoked activity in the hMT+ and the R aTPJ. We conclude that temporal selective attention is particularly sensitive for revealing information pathways between sensory and core cognitive control networks that, when damaged, can lead to nonspatial attention impairments in right parietal stroke patients. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. [Sugar Chain Construction of Functional Natural Products Using Plant Glucosyltransferases].

    Science.gov (United States)

    Mizukami, Hajime

    2015-01-01

    Plant secondary product glycosyltransferases belong to family 1 of the glycosyltransferase superfamily and mediate the transfer of a glycosyl residue from activated nucleotide sugars to lipophilic small molecules, thus affecting the solubility, stability and pharmacological activities of the sugar-accepting compounds. The biotechnological application of plant glycosyltransferases in glycoside synthesis has attracted attention because enzymatic glycosylation offers several advantages over chemical methods, including (1) avoiding the use of harsh conditions and toxic catalysts, (2) providing strict control of regio-and stereo-selectivity and (3) high efficiency. This review describes the in vivo and in vitro glycosylation of natural organic compounds using glycosyltransferases, focusing on our investigation of enzymatic synthesis of curcumin glycosides. Our current efforts toward functional characterization of some glycosyltransferases involved in the biosynthesis of iridoids and crocin, as well as in the sugar chain elongation of quercetin glucosides, are described. Finally, I describe the relationship of the structure of sugar chains and the intestinal absorption which was investigated using chemoenzymatically synthesized quercetin glycosides.

  5. The Origin of Mutants Under Selection: How Natural Selection Mimics Mutagenesis (Adaptive Mutation)

    Science.gov (United States)

    Maisnier-Patin, Sophie; Roth, John R.

    2015-01-01

    Selection detects mutants but does not cause mutations. Contrary to this dictum, Cairns and Foster plated a leaky lac mutant of Escherichia coli on lactose medium and saw revertant (Lac+) colonies accumulate with time above a nongrowing lawn. This result suggested that bacteria might mutagenize their own genome when growth is blocked. However, this conclusion is suspect in the light of recent evidence that revertant colonies are initiated by preexisting cells with multiple copies the conjugative F′lac plasmid, which carries the lac mutation. Some plated cells have multiple copies of the simple F′lac plasmid. This provides sufficient LacZ activity to support plasmid replication but not cell division. In nongrowing cells, repeated plasmid replication increases the likelihood of a reversion event. Reversion to lac+ triggers exponential cell growth leading to a stable Lac+ revertant colony. In 10% of these plated cells, the high-copy plasmid includes an internal tandem lac duplication, which provides even more LacZ activity—sufficient to support slow growth and formation of an unstable Lac+ colony. Cells with multiple copies of the F′lac plasmid have an increased mutation rate, because the plasmid encodes the error-prone (mutagenic) DNA polymerase, DinB. Without DinB, unstable and stable Lac+ revertant types form in equal numbers and both types arise with no mutagenesis. Amplification and selection are central to behavior of the Cairns–Foster system, whereas mutagenesis is a system-specific side effect or artifact caused by coamplification of dinB with lac. Study of this system has revealed several broadly applicable principles. In all populations, gene duplications are frequent stable genetic polymorphisms, common near-neutral mutant alleles can gain a positive phenotype when amplified under selection, and natural selection can operate without cell division when variability is generated by overreplication of local genome subregions. PMID:26134316

  6. Selective Functionalization of Carbon Nanotubes: Part II

    Science.gov (United States)

    Meyyappan, Meyya; Khare, Bishun

    2010-01-01

    An alternative method of low-temperature plasma functionalization of carbon nanotubes provides for the simultaneous attachment of molecular groups of multiple (typically two or three) different species or different mixtures of species to carbon nanotubes at different locations within the same apparatus. This method is based on similar principles, and involves the use of mostly the same basic apparatus, as those of the methods described in "Low-Temperature Plasma Functionalization of Carbon Nanotubes" (ARC-14661-1), NASA Tech Briefs, Vol. 28, No. 5 (May 2004), page 45. The figure schematically depicts the basic apparatus used in the aforementioned method, with emphasis on features that distinguish the present alternative method from the other. In this method, one exploits the fact that the composition of the deposition plasma changes as the plasma flows from its source in the precursor chamber toward the nanotubes in the target chamber. As a result, carbon nanotubes mounted in the target chamber at different flow distances (d1, d2, d3 . . .) from the precursor chamber become functionalized with different species or different mixtures of species. In one series of experiments to demonstrate this method, N2 was used as the precursor gas. After the functionalization process, the carbon nanotubes from three different positions in the target chamber were examined by Fourier-transform infrared spectroscopy to identify the molecular groups that had become attached. On carbon nanotubes from d1 = 1 cm, the attached molecular groups were found to be predominantly C-N and C=N. On carbon nanotubes from d2 = 2.5 cm, the attached molecular groups were found to be predominantly C-(NH)2 and/or C=NH2. (The H2 was believed to originate as residual hydrogen present in the nanotubes.) On carbon nanotubes from d3 = 7 cm no functionalization could be detected - perhaps, it was conjectured, because this distance is downstream of the plasma source, all of the free ions and free radicals of

  7. Identifying signatures of natural selection in Tibetan and Andean populations using dense genome scan data.

    Directory of Open Access Journals (Sweden)

    Abigail Bigham

    2010-09-01

    Full Text Available High-altitude hypoxia (reduced inspired oxygen tension due to decreased barometric pressure exerts severe physiological stress on the human body. Two high-altitude regions where humans have lived for millennia are the Andean Altiplano and the Tibetan Plateau. Populations living in these regions exhibit unique circulatory, respiratory, and hematological adaptations to life at high altitude. Although these responses have been well characterized physiologically, their underlying genetic basis remains unknown. We performed a genome scan to identify genes showing evidence of adaptation to hypoxia. We looked across each chromosome to identify genomic regions with previously unknown function with respect to altitude phenotypes. In addition, groups of genes functioning in oxygen metabolism and sensing were examined to test the hypothesis that particular pathways have been involved in genetic adaptation to altitude. Applying four population genetic statistics commonly used for detecting signatures of natural selection, we identified selection-nominated candidate genes and gene regions in these two populations (Andeans and Tibetans separately. The Tibetan and Andean patterns of genetic adaptation are largely distinct from one another, with both populations showing evidence of positive natural selection in different genes or gene regions. Interestingly, one gene previously known to be important in cellular oxygen sensing, EGLN1 (also known as PHD2, shows evidence of positive selection in both Tibetans and Andeans. However, the pattern of variation for this gene differs between the two populations. Our results indicate that several key HIF-regulatory and targeted genes are responsible for adaptation to high altitude in Andeans and Tibetans, and several different chromosomal regions are implicated in the putative response to selection. These data suggest a genetic role in high-altitude adaption and provide a basis for future genotype/phenotype association

  8. Natural radioactivity monitoring in selected areas of the planet Earth

    International Nuclear Information System (INIS)

    Hobst, L.

    2015-01-01

    Mankind lives with the natural radioactivity throughout its development. The effects of radiation may affect to some extent the evolutionary development of life on the Earth. It is therefore important to find out what values can achieve this natural radioactivity at different places of the world. In this presentation some results of dose rate measurement during transcontinental flyers are discussed.

  9. North American Natural Gas Markets: Selected technical studies

    International Nuclear Information System (INIS)

    Huntington, H.G.; Schuler, G.E.

    1989-04-01

    The Energy Modeling Forum (EMF) was established in 1976 at Stanford University to provide a structural framework within which energy experts, analysts, and policymakers could meet to improve their understanding of critical energy problems. The ninth EMF study, North American Natural Gas Markets, was conducted by a working group comprised of leading natural gas analysts and decision-makers from government, private companies, universities, and research and consulting organizations. The EMF 9 working group met five times from October 1986 through June 1988 to discuss key issues and analyze natural gas markets. This third volume includes technical papers that support many of the conclusions discussed in the EMF 9 summary report (Volume 1) and full working group report (Volume 2). These papers discuss the results from the individual models as well as some nonmodeling analysis related to US natural gas imports and industrial natural gas demand. Individual papers have been processed separately for inclusion in the Energy Science and Technology Database

  10. North American Natural Gas Markets: Selected technical studies. Volume 3

    Energy Technology Data Exchange (ETDEWEB)

    Huntington, H.G.; Schuler, G.E. [eds.

    1989-04-01

    The Energy Modeling Forum (EMF) was established in 1976 at Stanford University to provide a structural framework within which energy experts, analysts, and policymakers could meet to improve their understanding of critical energy problems. The ninth EMF study, North American Natural Gas Markets, was conducted by a working group comprised of leading natural gas analysts and decision-makers from government, private companies, universities, and research and consulting organizations. The EMF 9 working group met five times from October 1986 through June 1988 to discuss key issues and analyze natural gas markets. This third volume includes technical papers that support many of the conclusions discussed in the EMF 9 summary report (Volume 1) and full working group report (Volume 2). These papers discuss the results from the individual models as well as some nonmodeling analysis related to US natural gas imports and industrial natural gas demand. Individual papers have been processed separately for inclusion in the Energy Science and Technology Database.

  11. North American Natural Gas Markets: Selected technical studies

    Energy Technology Data Exchange (ETDEWEB)

    Huntington, H.G.; Schuler, G.E. (eds.)

    1989-04-01

    The Energy Modeling Forum (EMF) was established in 1976 at Stanford University to provide a structural framework within which energy experts, analysts, and policymakers could meet to improve their understanding of critical energy problems. The ninth EMF study, North American Natural Gas Markets, was conducted by a working group comprised of leading natural gas analysts and decision-makers from government, private companies, universities, and research and consulting organizations. The EMF 9 working group met five times from October 1986 through June 1988 to discuss key issues and analyze natural gas markets. This third volume includes technical papers that support many of the conclusions discussed in the EMF 9 summary report (Volume 1) and full working group report (Volume 2). These papers discuss the results from the individual models as well as some nonmodeling analysis related to US natural gas imports and industrial natural gas demand. Individual papers have been processed separately for inclusion in the Energy Science and Technology Database.

  12. Evaluation of natural radionuclides in selected regions of Slovak Republic

    International Nuclear Information System (INIS)

    Porubcanova, B.; Mojzes, A.; Nikodemova, D.

    2014-01-01

    Slovakian part of Western Carpathian is an area typical for very various geological structures. This fact is also reflected on values of natural radionuclide concentrations. Our paper was focused on evaluation and collection of data about activities of different natural radionuclides (uranium, thorium and potassium) and on the description of rocks which cause it. For research purposes were offered the results obtained from middle and eastern Slovakia which includes different types of rocks with various values of radioactive concentrations. Consequently these data were processed and shown by maps that represent the values of natural radioactivity in the studied areas. (authors)

  13. Evaluation of natural radionuclides in selected regions of Slovak Republic

    International Nuclear Information System (INIS)

    Porubcanova, B.; Nikodemova, D.; Mojzes, A.

    2014-01-01

    Slovakian part of Western Carpathian is an area typical for very various geological structures. This fact is also reflected on values of natural radionuclide concentrations. Our poster was focused on evaluation and collection of data about activities of different natural radionuclides (uranium, thorium and potassium) and on the description of rocks which cause it. For research purposes were offered the results obtained from middle and eastern Slovakia which includes different types of rocks with various values of radioactive concentrations. Consequently these data were processed and shown by maps that represent the values of natural radioactivity in the studied areas. (authors)

  14. Natural ingredients based cosmetics. Content of selected fragrance sensitizers

    DEFF Research Database (Denmark)

    Rastogi, Suresh Chandra; Johansen, J D; Menné, T

    1996-01-01

    In the present study, we have investigated 42 cosmetic products based on natural ingredients for content of 11 fragrance substances: geraniol, hydroxycitronellal, eugenol, isoeugenol, cinnamic aldehyde, cinnamic alcohol, alpha-amylcinnamic aldehyde, citral, coumarin, dihydrocoumarin and alpha......-hexylcinnamic aldehyde. The study revealed that the 91% (20/22) of the natural ingredients based perfumes contained 0.027%-7.706% of 1 to 7 of the target fragrances. Between 1 and 5 of the chemically defined synthetic constituents of fragrance mix were found in 82% (18/22) of the perfumes. 35% (7/20) of the other...... of hydroxycitronellal and alpha-hexylcinnamic aldehyde in some of the products demonstrates that artificial fragrances, i.e., compounds not yet regarded as natural substances, may be present in products claimed to be based on natural ingredients....

  15. Natural selection of mitochondria during somatic lifetime promotes healthy aging

    DEFF Research Database (Denmark)

    Rodell, Anders; Rasmussen, Lene J; Bergersen, Linda H

    2013-01-01

    Stimulation of mitochondrial biogenesis during life-time challenges both eliminates disadvantageous properties and drives adaptive selection of advantageous phenotypic variations. Intermittent fission and fusion of mitochondria provide specific targets for health promotion by brief temporal...... stressors, interspersed with periods of recovery and biogenesis. For mitochondria, the mechanisms of selection, variability, and heritability, are complicated by interaction of two independent genomes, including the multiple copies of DNA in each mitochondrion, as well as the shared nuclear genome of each...

  16. Predation and selection for antibiotic resistance in natural environments

    DEFF Research Database (Denmark)

    Leisner, Jørgen; Jørgensen, Niels O. G.; Middelboe, Mathias

    2016-01-01

    Genes encoding resistance to antibiotics appear, like the antibiotics themselves, to be ancient, originating long before the rise of the era of anthropogenic antibiotics. However, detailed understanding of the specific biological advantages of antibiotic resistance in natural environments is still...... lacking, thus limiting our efforts to prevent environmental influx of resistance genes. Here, we propose that antibiotic-resistant cells not only evade predation from antibiotic producers but also take advantage of nutrients released from cells that are killed by the antibiotic-producing bacteria. Thus......, predation is potentially an important mechanism for driving antibiotic resistance during slow or stationary phase of growth when nutrients are deprived. This adds to explain the ancient nature and widespread occurrence of antibiotic resistance in natural environments unaffected by anthropogenic antibiotics...

  17. Implicit function with natural behavior over entire domain

    International Nuclear Information System (INIS)

    Itoh, Taku; Saitoh, Ayumu; Kamitani, Atsushi; Nakamura, Hiroaki

    2012-01-01

    To generate a smooth implicit function that behaves naturally over an entire domain, a method to smoothly combine an implicit function f(x) with a global support function g(x) has been proposed. The proposed method can be applied to large scattered point data, since the implicit function f(x) is generated by a partition-of-unity-based method. The global support function g(x) is generated by a radial basis function-based method or by the least-squares method. To ensure a smooth combination of f(x) and g(x), an appropriate weight function is employed. In numerical experiments, the proposed method is applied to large point data. The results illustrate that the proposed method can generate a smooth implicit function F(x) with natural behavior over the entire domain. In addition, on the given points, the accuracy of F(x) is exactly the same as that of f(x). Furthermore, the computational cost for generation of F(x) is almost the same as that of f(x). (author)

  18. Bacteria Associated to Plants Naturally Selected in a Historical PCB Polluted Soil Show Potential to Sustain Natural Attenuation.

    Science.gov (United States)

    Vergani, Lorenzo; Mapelli, Francesca; Marasco, Ramona; Crotti, Elena; Fusi, Marco; Di Guardo, Antonio; Armiraglio, Stefano; Daffonchio, Daniele; Borin, Sara

    2017-01-01

    The exploitation of the association between plants and microorganisms is a promising approach able to boost natural attenuation processes for soil clean-up in vast polluted areas characterized by mixed chemical contamination. We aimed to explore the selection of root-associated bacterial communities driven by different plant species spontaneously established in abandoned agricultural soils within a historical polluted site in north Italy. The site is highly contaminated by chlorinated persistent organic pollutants, mainly constituted by polychlorobiphenyls (PCBs), together with heavy metals and metalloids, in variable concentrations and uneven distribution. The overall structure of the non-vegetated and root-associated soil fractions bacterial communities was described by high-throughput sequencing of the 16S rRNA gene, and a collection of 165 rhizobacterial isolates able to use biphenyl as unique carbon source was assayed for plant growth promotion (PGP) traits and bioremediation potential. The results showed that the recruitment of specific bacterial communities in the root-associated soil fractions was driven by both soil fractions and plant species, explaining 21 and 18% of the total bacterial microbiome variation, respectively. PCR-based detection in the soil metagenome of bacterial bphA gene, encoding for the biphenyl dioxygenase α subunit, indicated that the soil in the site possesses metabolic traits linked to PCB degradation. Biphenyl-utilizing bacteria isolated from the rhizosphere of the three different plant species showed low phylogenetic diversity and well represented functional traits, in terms of PGP and bioremediation potential. On average, 72% of the strains harbored the bphA gene and/or displayed catechol 2,3-dioxygenase activity, involved in aromatic ring cleavage. PGP traits, including 1-aminocyclopropane-1-carboxylic acid deaminase activity potentially associated to plant stress tolerance induction, were widely distributed among the isolates

  19. Bacteria Associated to Plants Naturally Selected in a Historical PCB Polluted Soil Show Potential to Sustain Natural Attenuation

    KAUST Repository

    Vergani, Lorenzo

    2017-07-25

    The exploitation of the association between plants and microorganisms is a promising approach able to boost natural attenuation processes for soil clean-up in vast polluted areas characterized by mixed chemical contamination. We aimed to explore the selection of root-associated bacterial communities driven by different plant species spontaneously established in abandoned agricultural soils within a historical polluted site in north Italy. The site is highly contaminated by chlorinated persistent organic pollutants, mainly constituted by polychlorobiphenyls (PCBs), together with heavy metals and metalloids, in variable concentrations and uneven distribution. The overall structure of the non-vegetated and root-associated soil fractions bacterial communities was described by high-throughput sequencing of the 16S rRNA gene, and a collection of 165 rhizobacterial isolates able to use biphenyl as unique carbon source was assayed for plant growth promotion (PGP) traits and bioremediation potential. The results showed that the recruitment of specific bacterial communities in the root-associated soil fractions was driven by both soil fractions and plant species, explaining 21 and 18% of the total bacterial microbiome variation, respectively. PCR-based detection in the soil metagenome of bacterial bphA gene, encoding for the biphenyl dioxygenase α subunit, indicated that the soil in the site possesses metabolic traits linked to PCB degradation. Biphenyl-utilizing bacteria isolated from the rhizosphere of the three different plant species showed low phylogenetic diversity and well represented functional traits, in terms of PGP and bioremediation potential. On average, 72% of the strains harbored the bphA gene and/or displayed catechol 2,3-dioxygenase activity, involved in aromatic ring cleavage. PGP traits, including 1-aminocyclopropane-1-carboxylic acid deaminase activity potentially associated to plant stress tolerance induction, were widely distributed among the isolates

  20. Bacteria Associated to Plants Naturally Selected in a Historical PCB Polluted Soil Show Potential to Sustain Natural Attenuation

    Directory of Open Access Journals (Sweden)

    Lorenzo Vergani

    2017-07-01

    Full Text Available The exploitation of the association between plants and microorganisms is a promising approach able to boost natural attenuation processes for soil clean-up in vast polluted areas characterized by mixed chemical contamination. We aimed to explore the selection of root-associated bacterial communities driven by different plant species spontaneously established in abandoned agricultural soils within a historical polluted site in north Italy. The site is highly contaminated by chlorinated persistent organic pollutants, mainly constituted by polychlorobiphenyls (PCBs, together with heavy metals and metalloids, in variable concentrations and uneven distribution. The overall structure of the non-vegetated and root-associated soil fractions bacterial communities was described by high-throughput sequencing of the 16S rRNA gene, and a collection of 165 rhizobacterial isolates able to use biphenyl as unique carbon source was assayed for plant growth promotion (PGP traits and bioremediation potential. The results showed that the recruitment of specific bacterial communities in the root-associated soil fractions was driven by both soil fractions and plant species, explaining 21 and 18% of the total bacterial microbiome variation, respectively. PCR-based detection in the soil metagenome of bacterial bphA gene, encoding for the biphenyl dioxygenase α subunit, indicated that the soil in the site possesses metabolic traits linked to PCB degradation. Biphenyl-utilizing bacteria isolated from the rhizosphere of the three different plant species showed low phylogenetic diversity and well represented functional traits, in terms of PGP and bioremediation potential. On average, 72% of the strains harbored the bphA gene and/or displayed catechol 2,3-dioxygenase activity, involved in aromatic ring cleavage. PGP traits, including 1-aminocyclopropane-1-carboxylic acid deaminase activity potentially associated to plant stress tolerance induction, were widely distributed

  1. Density functional theory, natural bond orbital and quantum theory of ...

    Indian Academy of Sciences (India)

    Density functional theory, natural bond orbital and quantum theory of atoms in molecule analyses on the hydrogen bonding interactions in tryptophan-water complexes. XIQIAN NIU, ZHENGGUO HUANG. ∗. , LINGLING MA, TINGTING SHEN and LINGFEI GUO. Tianjin Key Laboratory of Structure and Performance for ...

  2. Frugivorous bats maintain functional habitat connectivity in agricultural landscapes but rely strongly on natural forest fragments.

    Science.gov (United States)

    Ripperger, Simon P; Kalko, Elisabeth K V; Rodríguez-Herrera, Bernal; Mayer, Frieder; Tschapka, Marco

    2015-01-01

    Anthropogenic changes in land use threaten biodiversity and ecosystem functioning by the conversion of natural habitat into agricultural mosaic landscapes, often with drastic consequences for the associated fauna. The first step in the development of efficient conservation plans is to understand movement of animals through complex habitat mosaics. Therefore, we studied ranging behavior and habitat use in Dermanura watsoni (Phyllostomidae), a frugivorous bat species that is a valuable seed disperser in degraded ecosystems. Radio-tracking of sixteen bats showed that the animals strongly rely on natural forest. Day roosts were exclusively located within mature forest fragments. Selection ratios showed that the bats foraged selectively within the available habitat and positively selected natural forest. However, larger daily ranges were associated with higher use of degraded habitats. Home range geometry and composition of focal foraging areas indicated that wider ranging bats performed directional foraging bouts from natural to degraded forest sites traversing the matrix over distances of up to three hundred meters. This behavior demonstrates the potential of frugivorous bats to functionally connect fragmented areas by providing ecosystem services between natural and degraded sites, and highlights the need for conservation of natural habitat patches within agricultural landscapes that meet the roosting requirements of bats.

  3. Frugivorous bats maintain functional habitat connectivity in agricultural landscapes but rely strongly on natural forest fragments.

    Directory of Open Access Journals (Sweden)

    Simon P Ripperger

    Full Text Available Anthropogenic changes in land use threaten biodiversity and ecosystem functioning by the conversion of natural habitat into agricultural mosaic landscapes, often with drastic consequences for the associated fauna. The first step in the development of efficient conservation plans is to understand movement of animals through complex habitat mosaics. Therefore, we studied ranging behavior and habitat use in Dermanura watsoni (Phyllostomidae, a frugivorous bat species that is a valuable seed disperser in degraded ecosystems. Radio-tracking of sixteen bats showed that the animals strongly rely on natural forest. Day roosts were exclusively located within mature forest fragments. Selection ratios showed that the bats foraged selectively within the available habitat and positively selected natural forest. However, larger daily ranges were associated with higher use of degraded habitats. Home range geometry and composition of focal foraging areas indicated that wider ranging bats performed directional foraging bouts from natural to degraded forest sites traversing the matrix over distances of up to three hundred meters. This behavior demonstrates the potential of frugivorous bats to functionally connect fragmented areas by providing ecosystem services between natural and degraded sites, and highlights the need for conservation of natural habitat patches within agricultural landscapes that meet the roosting requirements of bats.

  4. Methods for selective functionalization and separation of carbon nanotubes

    Science.gov (United States)

    Strano, Michael S. (Inventor); Usrey, Monica (Inventor); Barone, Paul (Inventor); Dyke, Christopher A. (Inventor); Tour, James M. (Inventor); Kittrell, W. Carter (Inventor); Hauge, Robert H (Inventor); Smalley, Richard E. (Inventor); Marek, legal representative, Irene Marie (Inventor)

    2011-01-01

    The present invention is directed toward methods of selectively functionalizing carbon nanotubes of a specific type or range of types, based on their electronic properties, using diazonium chemistry. The present invention is also directed toward methods of separating carbon nanotubes into populations of specific types or range(s) of types via selective functionalization and electrophoresis, and also to the novel compositions generated by such separations.

  5. Optimal Bandwidth Selection for Kernel Density Functionals Estimation

    Directory of Open Access Journals (Sweden)

    Su Chen

    2015-01-01

    Full Text Available The choice of bandwidth is crucial to the kernel density estimation (KDE and kernel based regression. Various bandwidth selection methods for KDE and local least square regression have been developed in the past decade. It has been known that scale and location parameters are proportional to density functionals ∫γ(xf2(xdx with appropriate choice of γ(x and furthermore equality of scale and location tests can be transformed to comparisons of the density functionals among populations. ∫γ(xf2(xdx can be estimated nonparametrically via kernel density functionals estimation (KDFE. However, the optimal bandwidth selection for KDFE of ∫γ(xf2(xdx has not been examined. We propose a method to select the optimal bandwidth for the KDFE. The idea underlying this method is to search for the optimal bandwidth by minimizing the mean square error (MSE of the KDFE. Two main practical bandwidth selection techniques for the KDFE of ∫γ(xf2(xdx are provided: Normal scale bandwidth selection (namely, “Rule of Thumb” and direct plug-in bandwidth selection. Simulation studies display that our proposed bandwidth selection methods are superior to existing density estimation bandwidth selection methods in estimating density functionals.

  6. Hydroquinone and quinone-grafted porous carbons for highly selective CO2 capture from flue gases and natural gas upgrading

    NARCIS (Netherlands)

    Wang, J.; Krishna, R.; Yang, J.; Deng, S.

    2015-01-01

    Hydroquinone and quinone functional groups were grafted onto a hierarchical porous carbon framework via the Friedel-Crafts reaction to develop more efficient adsorbents for the selective capture and removal of carbon dioxide from flue gases and natural gas. The oxygen-doped porous carbons were

  7. Phenotypic selection on leaf water use efficiency and related ecophysiological traits for natural populations of desert sunflowers.

    Science.gov (United States)

    Donovan, Lisa A; Dudley, Susan A; Rosenthal, David M; Ludwig, Fulco

    2007-05-01

    Plant water-use efficiency (WUE) is expected to affect plant fitness and thus be under natural selection in arid habitats. Although many natural population studies have assessed plant WUE, only a few related WUE to fitness. The further determination of whether selection on WUE is direct or indirect through functionally related traits has yielded no consistent results. For natural populations of two desert annual sunflowers, Helianthus anomalus and H. deserticola, we used phenotypic selection analysis with vegetative biomass as the proxy for fitness to test (1) whether there was direct and indirect selection on WUE (carbon isotope ratio) and related traits (leaf N, area, succulence) and (2) whether direct selection was consistent with hypothesized drought/dehydration escape and avoidance strategies. There was direct selection for lower WUE in mesic and dry H. anomalus populations, consistent with dehydration escape, even though it is the longer lived of the two species. For mesic H. anomalus, direct selection favored lower WUE and higher N, suggesting that plants may be "wasting water" to increase N delivery via the transpiration stream. For the shorter lived H. deserticola in the direr habitat, there was indirect selection for lower WUE, inconsistent with drought escape. There was also direct selection for higher leaf N, succulence and leaf size. There was no direct selection for higher WUE consistent with dehydration avoidance in either species. Thus, in these natural populations of two desert dune species higher fitness was associated with some combination direct and indirect selection for lower WUE, higher leaf N and larger leaf size. Our understanding of the adaptive value of plant ecophysiological traits will benefit from further consideration of related traits such as leaf nitrogen and more tests in natural populations.

  8. Genetic signature of natural selection in first Americans.

    Science.gov (United States)

    Amorim, Carlos Eduardo; Nunes, Kelly; Meyer, Diogo; Comas, David; Bortolini, Maria Cátira; Salzano, Francisco Mauro; Hünemeier, Tábita

    2017-02-28

    When humans moved from Asia toward the Americas over 18,000 y ago and eventually peopled the New World they encountered a new environment with extreme climate conditions and distinct dietary resources. These environmental and dietary pressures may have led to instances of genetic adaptation with the potential to influence the phenotypic variation in extant Native American populations. An example of such an event is the evolution of the fatty acid desaturases ( FADS ) genes, which have been claimed to harbor signals of positive selection in Inuit populations due to adaptation to the cold Greenland Arctic climate and to a protein-rich diet. Because there was evidence of intercontinental variation in this genetic region, with indications of positive selection for its variants, we decided to compare the Inuit findings with other Native American data. Here, we use several lines of evidence to show that the signal of FADS-positive selection is not restricted to the Arctic but instead is broadly observed throughout the Americas. The shared signature of selection among populations living in such a diverse range of environments is likely due to a single and strong instance of local adaptation that took place in the common ancestral population before their entrance into the New World. These first Americans peopled the whole continent and spread this adaptive variant across a diverse set of environments.

  9. Allozyme diversity of selected and natural loblolly pine populations

    Science.gov (United States)

    Ronald C. Schmidtling; E. Carroll; T. LaFarge

    1999-01-01

    Loblolly pine (Pinus taeda L.) megagametophytes and embryos were examined electrophoretically to compare the extent and distribution of genetic variability in allozymes of selected and wild populations. Range-wide collections of three different types were investigated in this study. These consisted of seed sampled from (1) a provenance test...

  10. On the origin of species by natural and sexual selection

    NARCIS (Netherlands)

    van Doorn, G. Sander; Edelaar, Pim; Weissing, Franz J.

    2009-01-01

    Ecological speciation is considered an adaptive response to selection for local adaptation. However, besides suitable ecological conditions, the process requires assortative mating to protect the nascent species from homogenization by gene flow. By means of a simple model, we demonstrate that

  11. The relationship between nature-based tourism and autonomic nervous system function among older adults.

    Science.gov (United States)

    Chang, Liang-Chih

    2014-01-01

    Nature-based tourism has recently become a topic of interest in health research. This study was aimed at examining relationships among nature-based tourism, stress, and the function of the autonomic nervous system (ANS). Three hundred and twenty-two older adults living in Taichung City, Taiwan, were selected as participants. Data were collected by a face-to-face survey that included measures of the frequency of participation in domestic and international nature-based tourism and the stress and ANS function of these participants. The data were analyzed using a path analysis. The results demonstrated that the frequency of participation in domestic nature-based tourism directly contributed to ANS function and that it also indirectly contributed to ANS function through stress reduction. Domestic nature-based tourism can directly and indirectly contribute to ANS function among older adults. Increasing the frequency of participation in domestic nature-based tourism should be considered a critical element of health programs for older adults. © 2014 International Society of Travel Medicine.

  12. Assessment of natural radioactivity in the selected area of Slovakia

    International Nuclear Information System (INIS)

    Porubcanova, B.; Nikodemova, D.; Mojzes, A.

    2014-01-01

    Slovakia is country which has a difficult geological structure. This fact is reflected on values of natural radionuclide concentrations. A chosen area includes various types rocks which have diverse values of radioactive concentrations. Consequently these values were shown by maps which present localities with values of a radioactivity. This research was a first step which will be used like a base for a valorization and assessment of the potential radiation exposure of residents of SR where we can suppose health damage. (authors)

  13. Six Classroom Exercises to Teach Natural Selection to Undergraduate Biology Students

    Science.gov (United States)

    Kalinowski, Steven T.; Leonard, Mary J.; Andrews, Tessa M.; Litt, Andrea R.

    2013-01-01

    Students in introductory biology courses frequently have misconceptions regarding natural selection. In this paper, we describe six activities that biology instructors can use to teach undergraduate students in introductory biology courses how natural selection causes evolution. These activities begin with a lesson introducing students to natural…

  14. Evolution of Students' Ideas about Natural Selection through a Constructivist Framework

    Science.gov (United States)

    Baumgartner, Erin; Duncan, Kanesa

    2009-01-01

    Educating students about the process of evolution through natural selection is vitally important because not only is it the unifying theory of biological science, it is also widely regarded as difficult for students to fully comprehend. Anderson and colleagues (2002) describe alternative ideas and misconceptions about natural selection as highly…

  15. Phenotypic selection on leaf WUE and related ecophysiological traits for natural populations of desert sunflowers

    NARCIS (Netherlands)

    Donovan, L.A.; Rosenthal, D.R.; Dudley, S.A.; Ludwig, F.

    2007-01-01

    Plant water-use efficiency (WUE) is expected to affect plant fitness and thus be under natural selection in arid habitats. Although many natural population studies have assessed plant WUE, only a few related WUE to fitness. The further determination of whether selection on WUE is direct or indirect

  16. Weldon's Search for a Direct Proof of Natural Selection and the ...

    Indian Academy of Sciences (India)

    Plants under Domestication in 1868, there was considerable dis- agreement about whether natural selection could indeed work the. Keywords. Evolution, struggle for existence, natural selection, type, variations, heredity, biometrics, Mendelism. way Darwin had suggested and be the driving engine of adap- tive evolution.

  17. Instant Update: Considering the Molecular Mechanisms of Mutation & Natural Selection

    Science.gov (United States)

    Hubler, Tina; Adams, Patti; Scammell, Jonathan

    2015-01-01

    The molecular basis of evolution is an important concept to understand but one that students and teachers often find challenging. This article provides training and guidance for teachers on how to present molecular evolution concepts so that students will associate molecular changes with the evolution of form and function in organisms. Included…

  18. Compensatory selection for roads over natural linear features by wolves in northern Ontario: Implications for caribou conservation.

    Directory of Open Access Journals (Sweden)

    Erica J Newton

    Full Text Available Woodland caribou (Rangifer tarandus caribou in Ontario are a threatened species that have experienced a substantial retraction of their historic range. Part of their decline has been attributed to increasing densities of anthropogenic linear features such as trails, roads, railways, and hydro lines. These features have been shown to increase the search efficiency and kill rate of wolves. However, it is unclear whether selection for anthropogenic linear features is additive or compensatory to selection for natural (water linear features which may also be used for travel. We studied the selection of water and anthropogenic linear features by 52 resident wolves (Canis lupus x lycaon over four years across three study areas in northern Ontario that varied in degrees of forestry activity and human disturbance. We used Euclidean distance-based resource selection functions (mixed-effects logistic regression at the seasonal range scale with random coefficients for distance to water linear features, primary/secondary roads/railways, and hydro lines, and tertiary roads to estimate the strength of selection for each linear feature and for several habitat types, while accounting for availability of each feature. Next, we investigated the trade-off between selection for anthropogenic and water linear features. Wolves selected both anthropogenic and water linear features; selection for anthropogenic features was stronger than for water during the rendezvous season. Selection for anthropogenic linear features increased with increasing density of these features on the landscape, while selection for natural linear features declined, indicating compensatory selection of anthropogenic linear features. These results have implications for woodland caribou conservation. Prey encounter rates between wolves and caribou seem to be strongly influenced by increasing linear feature densities. This behavioral mechanism-a compensatory functional response to anthropogenic

  19. Sexual and natural selection in the evolution of extended phenotypes: the use of green nesting material in starlings.

    Science.gov (United States)

    Rubalcaba, J G; Polo, V; Maia, R; Rubenstein, D R; Veiga, J P

    2016-08-01

    Although sexual selection is typically considered the predominant force driving the evolution of ritualized sexual behaviours, natural selection may also play an important and often underappreciated role. The use of green aromatic plants among nesting birds has been interpreted as a component of extended phenotype that evolved either via natural selection due to potential sanitary functions or via sexual selection as a signal of male attractiveness. Here, we compared both hypotheses using comparative methods in starlings, a group where this behaviour is widespread. We found that the use of green plants was positively related to male-biased size dimorphism and that it was most likely to occur among cavity-nesting species. These results suggest that this behaviour is likely favoured by sexual selection, but also related to its sanitary use in response to higher parasite loads in cavities. We speculate that the use of green plants in starlings may be facilitated by cavity nesting and was subsequently co-opted as a sexual signal by males. Our results represent an example of how an extended phenotypic component of males becomes sexually selected by females. Thus, both natural selection and sexual selection are necessary to fully understand the evolution of ritualized behaviours involved in courtship. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  20. Sperm selection in natural conception: what can we learn from Mother Nature to improve assisted reproduction outcomes?

    Science.gov (United States)

    Sakkas, Denny; Ramalingam, Mythili; Garrido, Nicolas; Barratt, Christopher L.R.

    2015-01-01

    BACKGROUND In natural conception only a few sperm cells reach the ampulla or the site of fertilization. This population is a selected group of cells since only motile cells can pass through cervical mucus and gain initial entry into the female reproductive tract. In animals, some studies indicate that the sperm selected by the reproductive tract and recovered from the uterus and the oviducts have higher fertilization rates but this is not a universal finding. Some species show less discrimination in sperm selection and abnormal sperm do arrive at the oviduct. In contrast, assisted reproductive technologies (ART) utilize a more random sperm population. In this review we contrast the journey of the spermatozoon in vivo and in vitro and discuss this in the context of developing new sperm preparation and selection techniques for ART. METHODS A review of the literature examining characteristics of the spermatozoa selected in vivo is compared with recent developments in in vitro selection and preparation methods. Contrasts and similarities are presented. RESULTS AND CONCLUSIONS New technologies are being developed to aid in the diagnosis, preparation and selection of spermatozoa in ART. To date progress has been frustrating and these methods have provided variable benefits in improving outcomes after ART. It is more likely that examining the mechanisms enforced by nature will provide valuable information in regard to sperm selection and preparation techniques in vitro. Identifying the properties of those spermatozoa which do reach the oviduct will also be important for the development of more effective tests of semen quality. In this review we examine the value of sperm selection to see how much guidance for ART can be gleaned from the natural selection processes in vivo. PMID:26386468

  1. Descriptive Topology in Selected Topics of Functional Analysis

    CERN Document Server

    Kakol, J; Pellicer, Manuel Lopez

    2011-01-01

    "Descriptive Topology in Selected Topics of Functional Analysis" is a collection of recent developments in the field of descriptive topology, specifically focused on the classes of infinite-dimensional topological vector spaces that appear in functional analysis. Such spaces include Frechet spaces, (LF)-spaces and their duals, and the space of continuous real-valued functions C(X) on a completely regular Hausdorff space X, to name a few. These vector spaces appear in functional analysis in distribution theory, differential equations, complex analysis, and various other analytical set

  2. Functionalization of Liquid Natural Rubber via Oxidative Degradation of Natural Rubber

    Directory of Open Access Journals (Sweden)

    Suhawati Ibrahim

    2014-12-01

    Full Text Available Natural rubber (NR is a high molecular weight natural polymer and can be degraded to liquid natural rubber (LNR leaving certain functional groups at the end of chains. In this study, LNR samples prepared via oxidative degradation using H2O2 and NaNO2 as reagents were found to have different end groups depending on the pH of the reaction medium. In an acidic medium, LNR with hydroxyl terminal groups was formed as the degradation reaction was initiated by hydroxyl radicals produced from decomposition of peroxynitrite acid. In contrast, a redox reaction took place in an alkaline medium to yield LNR with carbonyl terminal groups. The mechanisms of reaction are discussed and proposed to explain the formation of different end groups when reaction carried out in acidic and alkaline media. Chain degradation in an acidic medium seems to be more effective than in an alkaline medium, and thus yields LNR with lower Mn.

  3. "Wrecks of Ancient Life": Genetic Variants Vetted by Natural Selection.

    Science.gov (United States)

    Postlethwait, John H

    2015-07-01

    The Genetics Society of America's George W. Beadle Award honors individuals who have made outstanding contributions to the community of genetics researchers and who exemplify the qualities of its namesake as a respected academic, administrator, and public servant. The 2015 recipient is John Postlethwait. He has made groundbreaking contributions in developing the zebrafish as a molecular genetic model and in understanding the evolution of new gene functions in vertebrates. He built the first zebrafish genetic map and showed that its genome, along with that of distantly related teleost fish, had been duplicated. Postlethwait played an integral role in the zebrafish genome-sequencing project and elucidated the genomic organization of several fish species. Postlethwait is also honored for his active involvement with the zebrafish community, advocacy for zebrafish as a model system, and commitment to driving the field forward. Copyright © 2015 by the Genetics Society of America.

  4. Opportunity for natural selection among five population groups of Manipur, North East India.

    Science.gov (United States)

    Asghar, M; Meitei, S Y; Luxmi, Y; Achoubi, N; Meitei, K S; Murry, B; Sachdeva, M P; Saraswathy, K N

    2014-01-01

    Opportunity for natural selection among five population groups of Manipur in comparison with other North East Indian population has been studied. Crow's index as well as Johnston and Kensinger's index for natural selection were calculated based on differential fertility and mortality. The mortality component was found to be lower compared to fertility component in all the populations which may attribute to comparatively improved and easily accessible health care facilities. However, different selection pressures, artificial and natural, seem to be influencing the selection intensity through induced abortion and spontaneous abortion among the two non-tribal migrant groups: Bamon and Muslims, respectively. This study highlights the probable interaction of artificial and natural selection in determining the evolutionary fate of any population group.

  5. Genetic diversity and natural selection of Plasmodium knowlesi merozoite surface protein 1 paralog gene in Malaysia.

    Science.gov (United States)

    Ahmed, Md Atique; Fauzi, Muh; Han, Eun-Taek

    2018-03-14

    Human infections due to the monkey malaria parasite Plasmodium knowlesi is on the rise in most Southeast Asian countries specifically Malaysia. The C-terminal 19 kDa domain of PvMSP1P is a potential vaccine candidate, however, no study has been conducted in the orthologous gene of P. knowlesi. This study investigates level of polymorphisms, haplotypes and natural selection of full-length pkmsp1p in clinical samples from Malaysia. A total of 36 full-length pkmsp1p sequences along with the reference H-strain and 40 C-terminal pkmsp1p sequences from clinical isolates of Malaysia were downloaded from published genomes. Genetic diversity, polymorphism, haplotype and natural selection were determined using DnaSP 5.10 and MEGA 5.0 software. Genealogical relationships were determined using haplotype network tree in NETWORK software v5.0. Population genetic differentiation index (F ST ) and population structure of parasite was determined using Arlequin v3.5 and STRUCTURE v2.3.4 software. Comparison of 36 full-length pkmsp1p sequences along with the H-strain identified 339 SNPs (175 non-synonymous and 164 synonymous substitutions). The nucleotide diversity across the full-length gene was low compared to its ortholog pvmsp1p. The nucleotide diversity was higher toward the N-terminal domains (pkmsp1p-83 and 30) compared to the C-terminal domains (pkmsp1p-38, 33 and 19). Phylogenetic analysis of full-length genes identified 2 distinct clusters of P. knowlesi from Malaysian Borneo. The 40 pkmsp1p-19 sequences showed low polymorphisms with 16 polymorphisms leading to 18 haplotypes. In total there were 10 synonymous and 6 non-synonymous substitutions and 12 cysteine residues were intact within the two EGF domains. Evidence of strong purifying selection was observed within the full-length sequences as well in all the domains. Shared haplotypes of 40 pkmsp1p-19 were identified within Malaysian Borneo haplotypes. This study is the first to report on the genetic diversity and natural

  6. Selecting the Number of Principal Components in Functional Data

    KAUST Repository

    Li, Yehua

    2013-12-01

    Functional principal component analysis (FPCA) has become the most widely used dimension reduction tool for functional data analysis. We consider functional data measured at random, subject-specific time points, contaminated with measurement error, allowing for both sparse and dense functional data, and propose novel information criteria to select the number of principal component in such data. We propose a Bayesian information criterion based on marginal modeling that can consistently select the number of principal components for both sparse and dense functional data. For dense functional data, we also develop an Akaike information criterion based on the expected Kullback-Leibler information under a Gaussian assumption. In connecting with the time series literature, we also consider a class of information criteria proposed for factor analysis of multivariate time series and show that they are still consistent for dense functional data, if a prescribed undersmoothing scheme is undertaken in the FPCA algorithm. We perform intensive simulation studies and show that the proposed information criteria vastly outperform existing methods for this type of data. Surprisingly, our empirical evidence shows that our information criteria proposed for dense functional data also perform well for sparse functional data. An empirical example using colon carcinogenesis data is also provided to illustrate the results. Supplementary materials for this article are available online. © 2013 American Statistical Association.

  7. The mathematics of random mutation and natural selection for multiple simultaneous selection pressures and the evolution of antimicrobial drug resistance.

    Science.gov (United States)

    Kleinman, Alan

    2016-12-20

    The random mutation and natural selection phenomenon act in a mathematically predictable behavior, which when understood leads to approaches to reduce and prevent the failure of the use of these selection pressures when treating infections and cancers. The underlying principle to impair the random mutation and natural selection phenomenon is to use combination therapy, which forces the population to evolve to multiple selection pressures simultaneously that invoke the multiplication rule of probabilities simultaneously as well. Recently, it has been seen that combination therapy for the treatment of malaria has failed to prevent the emergence of drug-resistant variants. Using this empirical example and the principles of probability theory, the derivation of the equations describing this treatment failure is carried out. These equations give guidance as to how to use combination therapy for the treatment of cancers and infectious diseases and prevent the emergence of drug resistance. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  8. H4: A challenging system for natural orbital functional approximations

    International Nuclear Information System (INIS)

    Ramos-Cordoba, Eloy; Lopez, Xabier; Piris, Mario; Matito, Eduard

    2015-01-01

    The correct description of nondynamic correlation by electronic structure methods not belonging to the multireference family is a challenging issue. The transition of D 2h to D 4h symmetry in H 4 molecule is among the most simple archetypal examples to illustrate the consequences of missing nondynamic correlation effects. The resurgence of interest in density matrix functional methods has brought several new methods including the family of Piris Natural Orbital Functionals (PNOF). In this work, we compare PNOF5 and PNOF6, which include nondynamic electron correlation effects to some extent, with other standard ab initio methods in the H 4 D 4h /D 2h potential energy surface (PES). Thus far, the wrongful behavior of single-reference methods at the D 2h –D 4h transition of H 4 has been attributed to wrong account of nondynamic correlation effects, whereas in geminal-based approaches, it has been assigned to a wrong coupling of spins and the localized nature of the orbitals. We will show that actually interpair nondynamic correlation is the key to a cusp-free qualitatively correct description of H 4 PES. By introducing interpair nondynamic correlation, PNOF6 is shown to avoid cusps and provide the correct smooth PES features at distances close to the equilibrium, total and local spin properties along with the correct electron delocalization, as reflected by natural orbitals and multicenter delocalization indices

  9. H4: A challenging system for natural orbital functional approximations

    Science.gov (United States)

    Ramos-Cordoba, Eloy; Lopez, Xabier; Piris, Mario; Matito, Eduard

    2015-10-01

    The correct description of nondynamic correlation by electronic structure methods not belonging to the multireference family is a challenging issue. The transition of D2h to D4h symmetry in H4 molecule is among the most simple archetypal examples to illustrate the consequences of missing nondynamic correlation effects. The resurgence of interest in density matrix functional methods has brought several new methods including the family of Piris Natural Orbital Functionals (PNOF). In this work, we compare PNOF5 and PNOF6, which include nondynamic electron correlation effects to some extent, with other standard ab initio methods in the H4 D4h/D2h potential energy surface (PES). Thus far, the wrongful behavior of single-reference methods at the D2h-D4h transition of H4 has been attributed to wrong account of nondynamic correlation effects, whereas in geminal-based approaches, it has been assigned to a wrong coupling of spins and the localized nature of the orbitals. We will show that actually interpair nondynamic correlation is the key to a cusp-free qualitatively correct description of H4 PES. By introducing interpair nondynamic correlation, PNOF6 is shown to avoid cusps and provide the correct smooth PES features at distances close to the equilibrium, total and local spin properties along with the correct electron delocalization, as reflected by natural orbitals and multicenter delocalization indices.

  10. Predicting richness effects on ecosystem function in natural communities

    DEFF Research Database (Denmark)

    Dangles, Olivier; Crespo-Pérez, Verónica; Andino, Patricio

    2011-01-01

    rates in the field, although water discharge may also play a role locally. We also examined the relative contribution of the three most abundant shredders on decomposition rates by manipulating shredder richness and community composition in a field experiment. Transgressive overyielding was detected....... Despite the increased complexity of experimental and theoretical studies on the biodiversity-ecosystem functioning (B-EF) relationship, a major challenge is to demonstrate whether the observed importance of biodiversity in controlled experimental systems also persists in nature. Due...... to their structural simplicity and their low levels of human impacts, extreme species-poor ecosystems may provide new insights into B-EF relationships in natural systems. We address this issue using shredder invertebrate communities and organic matter decomposition rates in 24 high-altitude (3200-3900 m) Neotropical...

  11. Covalently functionalized graphene sheets with biocompatible natural amino acids

    International Nuclear Information System (INIS)

    Mallakpour, Shadpour; Abdolmaleki, Amir; Borandeh, Sedigheh

    2014-01-01

    Graphene sheets were covalently functionalized with aromatic–aliphatic amino acids (phenylalanine and tyrosine) and aliphatic amino acids (alanine, isoleucine, leucine, methionine and valine) by simple and green procedure. For this aim, at first natural graphite was converted into graphene oxide (GO) through strong oxidation procedure; then, based on the surface-exposed epoxy and carboxylic acid groups in GO solid, its surface modification with naturally occurring amino acids, occurred easily throughout the corresponding nucleophilic substitution and condensation reactions. Amino acid functionalized graphene demonstrates stable dispersion in water and common organic solvents. Fourier transform infrared, Raman and X-ray photoelectron spectroscopies, X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy were used to investigate the nanostructures and properties of prepared materials. Each amino acid has different considerable effects on the structure and morphology of the pure graphite, from increasing the layer spacing to layer scrolling, based on their structures, functional groups and chain length. In addition, therogravimetric analysis was used for demonstrating a successful grafting of amino acid molecules to the surface of graphene.

  12. The response of natural enemies to selective insecticides applied to soybean.

    Science.gov (United States)

    Varenhorst, A J; O'Neal, M E

    2012-12-01

    Natural enemies of the invasive pest Aphis glycines Matsumura can prevent its establishment and population growth. However, current A. glycines management practices include the application of broad-spectrum insecticides that affect pests and natural enemies that are present in the field at the time of application. An alternative is the use of selective insecticides that affect the targeted pest species, although having a reduced impact on the natural enemies. We tested the effects of esfenvalerate, spirotetramat, imidacloprid, and a combination of spirotetramat and imidacloprid on the natural enemies in soybean during the 2009 and 2010 field season. The natural enemy community that was tested differed significantly between 2009 and 2010 (F = 87.41; df = 1, 598; P natural enemy in 2009 was Harmonia axyridis (Pallas) (56.0%) and in 2010 was Orius insidiosus (Say) (41.0%). During 2009, the abundance of natural enemies did not vary between the broad-spectrum and selective insecticides; however, the abundance of natural enemies was reduced by all insecticide treatments when compared with the untreated control. In 2010, the selective insecticide imidacloprid had more natural enemies than the broad-spectrum insecticide. Although we did not observe a difference in the abundance of the total natural enemy community in 2009, we did observe more H. axyridis in plots treated with spirotetramat. In 2010, we observed more O. insidiosus in plots treated with imidacloprid. We suggest a couple of mechanisms to explain how the varying insecticides have different impacts on separate components of the natural enemy community.

  13. Opportunity for natural selection among some selected population groups of Northeast India

    Science.gov (United States)

    Das, Farida Ahmed; Mithun, Sikdar

    2010-01-01

    BACKGROUND: Selection potential based on differential fertility and mortality has been computed for seven population groups inhabiting different geographical locations of Northeast India. MATERIALS AND METHODS: Crow’s as well as Johnston and Kensinger’s index have been used for the present purpose. RESULTS AND CONCLUSION: Irrespective of the methodology, the total index of selection was found to be highest among the Deoris followed by the Kaibartas. The lowest selection index was found among the Oraon population. If the relative contribution of fertility and mortality components to the total index is considered to be multiplicative, it is observed that in all these communities the fertility component exceeds that of mortality component, which may indicate initiation of demographic transitional phase in the selected populations with the betterment of healthcare and socioeconomic condition within the last few decades. PMID:21031053

  14. Opportunity for natural selection among some selected population groups of Northeast India.

    Science.gov (United States)

    Das, Farida Ahmed; Mithun, Sikdar

    2010-05-01

    Selection potential based on differential fertility and mortality has been computed for seven population groups inhabiting different geographical locations of Northeast India. Crow's as well as Johnston and Kensinger's index have been used for the present purpose. Irrespective of the methodology, the total index of selection was found to be highest among the Deoris followed by the Kaibartas. The lowest selection index was found among the Oraon population. If the relative contribution of fertility and mortality components to the total index is considered to be multiplicative, it is observed that in all these communities the fertility component exceeds that of mortality component, which may indicate initiation of demographic transitional phase in the selected populations with the betterment of healthcare and socioeconomic condition within the last few decades.

  15. Functional Assessment-Based Intervention for Selective Mutism

    Science.gov (United States)

    Kern, Lee; Starosta, Kristin M.; Bambara, Linda M.; Cook, Clayton R.; Gresham, Frank R.

    2007-01-01

    The process of functional assessment has emerged as an essential component for intervention development. Applications across divergent types of problem behavior, however, remain limited. This study evaluated the applicability of this promising approach to students with selective mutism. Two middle school students served as participants. The…

  16. The Lean Reference Collection: Improving Functionality through Selection and Weeding.

    Science.gov (United States)

    Nolan, Christopher W.

    1991-01-01

    Discusses references collections in academic libraries and offers guidelines for placing materials in a reference collection that focus on their suitability for true reference functions and the expected frequency of use. Problems with poorly managed collections are discussed, and the importance of selection policies and weeding are emphasized. (37…

  17. Concentration-mortality responses of Myzus persicae and natural enemies to selected insecticides.

    Science.gov (United States)

    Bacci, Leandro; Rosado, Jander F; Picanço, Marcelo C; Pereira, Eliseu J G; Silva, Gerson A; Martins, Júlio C

    2012-01-01

    The toxicity of six insecticides was determined for the peach-potato aphid, Myzus persicae (Hemiptera: Aphididae), and some of its natural enemies - the predatory beetles Cycloneda sanguinea (Coccinellidae) and Acanthinus sp. (Anthicidae), and the wasp parasitoid Diaeretiella rapae (Aphidiidae). Natural enemies from these groups are important natural biological control agents in a number of agroecosystems, and insecticides potentially safe to these non-target organisms should be identified using standardized tests. Thus, concentration-mortality bioassays were carried out with both the aphid and its natural enemies to assess the toxicity and selectivity of acephate, deltamethrin, dimethoate, methamidophos, methyl parathion, and pirimicarb. The latter insecticide was highly selective to all natural enemies tested, and its LC(90) for M. persicae was 14-fold lower than the field rate recommended for control of the aphid in brassica crops. Methyl parathion also showed selectivity to C. sanguinea and Acanthinus sp., but not to D. rapae. Acephate was the least potent insecticide against M. persicae and was equally or more toxic to the natural enemies relative to the aphid. Pirimicarb and methyl parathion were efficient against M. persicae and selective in favor of two of the natural enemies tested. Acanthinus sp. and C. sanguinea were more tolerant to the insecticides than was the parasitoid D. rapae. This study shows that there are selective insecticides that may be compatible with conservation of natural enemies in brassica crops, which is important practical information to improve integrated pest management systems in these crops.

  18. Natural selection and the distribution of identity-by-descent in the human genome

    DEFF Research Database (Denmark)

    Albrechtsen, Anders; Moltke, Ida; Nielsen, Rasmus

    2010-01-01

    There has recently been considerable interest in detecting natural selection in the human genome. Selection will usually tend to increase identity-by-descent (IBD) among individuals in a population, and many methods for detecting recent and ongoing positive selection indirectly take advantage...... of this. In this article we show that excess IBD sharing is a general property of natural selection and we show that this fact makes it possible to detect several types of selection including a type that is otherwise difficult to detect: selection acting on standing genetic variation. Motivated by this......, we use a recently developed method for identifying IBD sharing among individuals from genome-wide data to scan populations from the new HapMap phase 3 project for regions with excess IBD sharing in order to identify regions in the human genome that have been under strong, very recent selection...

  19. Comparison of selection methods to deduce natural background levels for groundwater units

    NARCIS (Netherlands)

    Griffioen, J.; Passier, H.F.; Klein, J.

    2008-01-01

    Establishment of natural background levels (NBL) for groundwater is commonly performed to serve as reference when assessing the contamination status of groundwater units. We compare various selection methods to establish NBLs using groundwater quality data forfour hydrogeologically different areas

  20. Transferring the Selectivity of a Natural Antibody into a Molecularly Imprinted Polymer

    NARCIS (Netherlands)

    Schirhagl, Romana

    2017-01-01

    Natural antibodies are widely used for their unprecedented reproducibility and the remarkable selectivity for a wide range of analytes. However, biodegradability and the need to work in biocompatible environments limit their applications. Molecularly imprinted polymers are a robust alternative.

  1. What is adaptation by natural selection? Perspectives of an experimental microbiologist.

    Science.gov (United States)

    Lenski, Richard E

    2017-04-01

    Ever since Darwin, the role of natural selection in shaping the morphological, physiological, and behavioral adaptations of animals and plants across generations has been central to understanding life and its diversity. New discoveries have shown with increasing precision how genetic, molecular, and biochemical processes produce and express those organismal features during an individual's lifetime. When it comes to microorganisms, however, understanding the role of natural selection in producing adaptive solutions has historically been, and sometimes continues to be, contentious. This tension is curious because microbes enable one to observe the power of adaptation by natural selection with exceptional rigor and clarity, as exemplified by the burgeoning field of experimental microbial evolution. I trace the development of this field, describe an experiment with Escherichia coli that has been running for almost 30 years, and highlight other experiments in which natural selection has led to interesting dynamics and adaptive changes in microbial populations.

  2. Young children can be taught basic natural selection using a picture-storybook intervention.

    Science.gov (United States)

    Kelemen, Deborah; Emmons, Natalie A; Seston Schillaci, Rebecca; Ganea, Patricia A

    2014-04-01

    Adaptation by natural selection is a core mechanism of evolution. It is also one of the most widely misunderstood scientific processes. Misconceptions are rooted in cognitive biases found in preschoolers, yet concerns about complexity mean that adaptation by natural selection is generally not comprehensively taught until adolescence. This is long after untutored theoretical misunderstandings are likely to have become entrenched. In a novel approach, we explored 5- to 8-year-olds' capacities to learn a basic but theoretically coherent mechanistic explanation of adaptation through a custom storybook intervention. Experiment 1 showed that children understood the population-based logic of natural selection and also generalized it. Furthermore, learning endured 3 months later. Experiment 2 replicated these results and showed that children understood and applied an even more nuanced mechanistic causal explanation. The findings demonstrate that, contrary to conventional educational wisdom, basic natural selection is teachable in early childhood. Theory-driven interventions using picture storybooks with rich explanatory structure are beneficial.

  3. Biological factors of natural and artificial ecosystems stable (unstable) functioning

    Science.gov (United States)

    Pechurkin, Nikolai S.

    The problem of sustainable development of humanity on Earth and the problem of supporting human life in space have the same scientific and methodological bases. The key to solve both problems is a long term maintenance of balanced material cycle. As a whole, natural or artificial ecosystems are to be more closed than open, but their elements (links of systems) are to be substantially open in interactions with each other. Prolonged stable interactions of different links have to have unique joint results - closed material cycling or biotic turnover. It is necessary to include, at least, three types of main links into any system to support real material cycling: producers, consumers, reducers. Producer links are now under studies in many laboratories. It is evident that the higher productivity of link, the lower link stability. Especially, it concerns with parasite impact to plants. As usual, artificial ecosystems are more simple (incomplete) than natural ecosystems, sometimes, they have not enough links for prolonged stable functioning. For example, life support system for space flight can be incomplete in consumer link, having only some crew persons, instead of interacting populations of consumers. As for reducer link, it is necessary to "organize" a special coordinated work of microbial biocenoses to fulfill proper cycling. Possible evolution of links, their self development is a matter of special attention for the maintenance of prolonged stable functioning. It's the most danger for systems with populations of quickly reproducing, so-called, R - strategists, according to symbols of logistic equation. From another side, quick reproduction of R - strategists is able to increase artificial ecosystems and their links functioning. After some damages of system, R - strategist's link can be quickly "self repaired" up to level of normal functioning. Some experimental data of this kind and mathematical models are to be discussed in the paper. This work is supported by

  4. Natural selection drove metabolic specialization of the chromatophore in Paulinella chromatophora.

    Science.gov (United States)

    Valadez-Cano, Cecilio; Olivares-Hernández, Roberto; Resendis-Antonio, Osbaldo; DeLuna, Alexander; Delaye, Luis

    2017-04-14

    Genome degradation of host-restricted mutualistic endosymbionts has been attributed to inactivating mutations and genetic drift while genes coding for host-relevant functions are conserved by purifying selection. Unlike their free-living relatives, the metabolism of mutualistic endosymbionts and endosymbiont-originated organelles is specialized in the production of metabolites which are released to the host. This specialization suggests that natural selection crafted these metabolic adaptations. In this work, we analyzed the evolution of the metabolism of the chromatophore of Paulinella chromatophora by in silico modeling. We asked whether genome reduction is driven by metabolic engineering strategies resulted from the interaction with the host. As its widely known, the loss of enzyme coding genes leads to metabolic network restructuring sometimes improving the production rates. In this case, the production rate of reduced-carbon in the metabolism of the chromatophore. We reconstructed the metabolic networks of the chromatophore of P. chromatophora CCAC 0185 and a close free-living relative, the cyanobacterium Synechococcus sp. WH 5701. We found that the evolution of free-living to host-restricted lifestyle rendered a fragile metabolic network where >80% of genes in the chromatophore are essential for metabolic functionality. Despite the lack of experimental information, the metabolic reconstruction of the chromatophore suggests that the host provides several metabolites to the endosymbiont. By using these metabolites as intracellular conditions, in silico simulations of genome evolution by gene lose recover with 77% accuracy the actual metabolic gene content of the chromatophore. Also, the metabolic model of the chromatophore allowed us to predict by flux balance analysis a maximum rate of reduced-carbon released by the endosymbiont to the host. By inspecting the central metabolism of the chromatophore and the free-living cyanobacteria we found that by

  5. Natural selection constrains neutral diversity across a wide range of species.

    Science.gov (United States)

    Corbett-Detig, Russell B; Hartl, Daniel L; Sackton, Timothy B

    2015-04-01

    The neutral theory of molecular evolution predicts that the amount of neutral polymorphisms within a species will increase proportionally with the census population size (Nc). However, this prediction has not been borne out in practice: while the range of Nc spans many orders of magnitude, levels of genetic diversity within species fall in a comparatively narrow range. Although theoretical arguments have invoked the increased efficacy of natural selection in larger populations to explain this discrepancy, few direct empirical tests of this hypothesis have been conducted. In this work, we provide a direct test of this hypothesis using population genomic data from a wide range of taxonomically diverse species. To do this, we relied on the fact that the impact of natural selection on linked neutral diversity depends on the local recombinational environment. In regions of relatively low recombination, selected variants affect more neutral sites through linkage, and the resulting correlation between recombination and polymorphism allows a quantitative assessment of the magnitude of the impact of selection on linked neutral diversity. By comparing whole genome polymorphism data and genetic maps using a coalescent modeling framework, we estimate the degree to which natural selection reduces linked neutral diversity for 40 species of obligately sexual eukaryotes. We then show that the magnitude of the impact of natural selection is positively correlated with Nc, based on body size and species range as proxies for census population size. These results demonstrate that natural selection removes more variation at linked neutral sites in species with large Nc than those with small Nc and provides direct empirical evidence that natural selection constrains levels of neutral genetic diversity across many species. This implies that natural selection may provide an explanation for this longstanding paradox of population genetics.

  6. Microalgae, a Potential Natural Functional Food Source – a Review

    Directory of Open Access Journals (Sweden)

    Villarruel-López Angélica

    2017-12-01

    Full Text Available Microalgae are a group of microorganisms used in aquaculture. The number of studies regarding their use as a functional food has recently increased due to their nutritional and bioactive compounds such as polysaccharides, fatty acids, bioactive peptides, and pigments. Specific microalgal glucans (polysaccharides can activate the immune system or exert antioxidant and hypocholesterolemic effects. The importance of algal lipids is based on their polyunsaturated fatty acids, their anti-inflammatory effects, their modulation of lipid pathways, and their neuroprotective action. Microalgae peptides can bind or inhibit specific receptors in cardiovascular diseases and cancer, while carotenoids can act as potent antioxidants. The beneficial biological activity will depend on the specific microalga and its chemical constituents. Therefore, knowledge of the composition of microalgae would aid in identifying, selecting, and studying their functional effects.

  7. Family functioning in the aftermath of a natural disaster

    Directory of Open Access Journals (Sweden)

    McDermott Brett M

    2012-07-01

    Full Text Available Abstract Background Increased understanding of the complex determinants of adverse child mental health outcomes following acute stress such as natural disasters has led to a resurgence of interest in the role of parent psychopathology and parenting. The authors investigated whether family functioning in the post-disaster environment would be impaired relative to a non-exposed sample and potential correlates with family functioning such as disaster-related exposure and child posttraumatic mental health symptoms. Methods Three months after a category 5 tropical cyclone that impacted north Queensland Australia, school-based screening was undertaken to case identify children who may benefit from a mental health intervention. Along with obtaining informed consent, parents completed a measure of family functioning. Results Of 145 families of children aged 8 to 12 years, 28.3% met criteria for dysfunction on the Family Adjustment Device, double the frequency in a community sample. The dysfunction group was significantly more likely to have experienced more internalising (anxiety/depression symptoms. However, in an adjusted logistic regression model this group were not more likely to have elevated disaster-related exposure nor did children in these families validate more PTSD symptoms. Conclusions The implications of post-disaster discordant family functioning and possible different causal pathways for depressive and PTSD-related symptomatic responses to traumatic events are discussed.

  8. Developmental and Functional Control of Natural Killer Cells by Cytokines

    Directory of Open Access Journals (Sweden)

    Yang Wu

    2017-08-01

    Full Text Available Natural killer (NK cells are effective in combating infections and tumors and as such are tempting for adoptive transfer therapy. However, they are not homogeneous but can be divided into three main subsets, including cytotoxic, tolerant, and regulatory NK cells, with disparate phenotypes and functions in diverse tissues. The development and functions of such NK cells are controlled by various cytokines, such as fms-like tyrosine kinase 3 ligand (FL, kit ligand (KL, interleukin (IL-3, IL-10, IL-12, IL-18, transforming growth factor-β, and common-γ chain family cytokines, which operate at different stages by regulating distinct signaling pathways. Nevertheless, the specific roles of each cytokine that regulates NK cell development or that shapes different NK cell functions remain unclear. In this review, we attempt to describe the characteristics of each cytokine and the existing protocols to expand NK cells using different combinations of cytokines and feeder cells. A comprehensive understanding of the role of cytokines in NK cell development and function will aid the generation of better efficacy for adoptive NK cell treatment.

  9. Cost function for the natural gas transmission, industry: further considerations

    International Nuclear Information System (INIS)

    Massol, Olivier

    2009-01-01

    This article studies the cost function for the natural gas transmission industry. 60 years ago, Hollis B. Chenery published an important contribution that demonstrated how, in that particular industry, the production function of micro-economic theory can be rewritten with engineering variables (Chenery, 1949). In 2008, an article published in The Engineering Economist (Yepez, 2008) provided a refreshing revival on Chenery's seminal thoughts. In addition to a tribute to the late H.B. Chenery, this document offers some further comments and extensions on Yepez (2008). It provides a statistically estimated characterisation of the long-run scale economies and a discussion on the short-run economics of the duplication of existing equipments. As a first extension, we study the optimal design for infrastructure that is planned to transport a seasonally-varying flow of natural gas. The second extension analyzes the optimal degree of excess capacity to be built into a new infrastructure by a firm that expects a random rise in its output during the infrastructure's lifetime. (author)

  10. Natural selection on HFE in Asian populations contributes to enhanced non-heme iron absorption.

    Science.gov (United States)

    Ye, Kaixiong; Cao, Chang; Lin, Xu; O'Brien, Kimberly O; Gu, Zhenglong

    2015-06-10

    HFE, a major regulator of iron (Fe) homeostasis, has been suggested to be under positive selection in both European and Asian populations. While the genetic variant under selection in Europeans (a non-synonymous mutation, C282Y) has been relatively well-studied, the adaptive variant in Asians and its functional consequences are still unknown. Identifying the adaptive HFE variants in Asians will not only elucidate the evolutionary history and the genetic basis of population difference in Fe status, but also assist the future practice of genome-informed dietary recommendation. Using data from the International HapMap Project, we confirmed the signatures of positive selection on HFE in Asian populations and identified a candidate adaptive haplotype that is common in Asians (52.35-54.71%) but rare in Europeans (5.98%) and Africans (4.35%). The T allele at tag SNP rs9366637 (C/T) captured 95.8% of this Asian-common haplotype. A significantly reduced HFE expression was observed in individuals carrying T/T at rs9366637 compared to C/C and C/T, indicating a possible role of gene regulation in adaptation. We recruited 57 women of Asian descent and measured Fe absorption using stable isotopes in those homozygous at rs9366637. We observed a 22% higher absorption in women homozygous for the Asian-common haplotype (T/T) compared to the control genotype (C/C). Additionally, compared with a group of age-matched Caucasian women, Asian women exhibited significantly elevated Fe absorption. Our results indicate parallel adaptation of HFE gene in Europeans and Asians with different genetic variants. Moreover, natural selection on HFE may have contributed to elevated Fe absorption in Asians. This study regarding population differences in Fe homeostasis has significant medical impact as high Fe level has been linked to an increased disease risk of metabolic syndromes.

  11. The Ecological Dynamics of Natural Selection: Traits and the Coevolution of Community Structure.

    Science.gov (United States)

    McPeek, Mark A

    2017-05-01

    Natural selection has both genetic and ecological dynamics. The fitnesses of individuals change with their ecological context, and so the form and strength of selective agents change with abiotic factors and the phenotypes and abundances of interacting species. I use standard models of consumer-resource interactions to explore the ecological dynamics of natural selection and how various trait types influence these dynamics and the resulting structure of a community of coevolving species. Evolutionary optima favored by natural selection depend critically on the abundances of interacting species, and the traits of species can undergo dynamic cycling in limited areas of parameter space. The ecological dynamics of natural selection can also drive shifts from one adaptive peak to another, and these ecologically driven adaptive peak shifts are fundamental to the dynamics of niche differentiation. Moreover, this ecological differentiation is fostered in more productive and more benign environments where species interactions are stronger and where the selection gradients generated by species interactions are stronger. Finally, community structure resulting from coevolution depends fundamentally on the types of traits that underlie species interactions. The ecological dynamics of the process cannot be simplified, neglected, or ignored if we are to build a predictive theory of natural selection.

  12. Multilevel Selection Theory and the Evolutionary Functions of Transposable Elements.

    Science.gov (United States)

    Brunet, Tyler D P; Doolittle, W Ford

    2015-08-06

    One of several issues at play in the renewed debate over "junk DNA" is the organizational level at which genomic features might be seen as selected, and thus to exhibit function, as etiologically defined. The intuition frequently expressed by molecular geneticists that junk DNA is functional because it serves to "speed evolution" or as an "evolutionary repository" could be recast as a claim about selection between species (or clades) rather than within them, but this is not often done. Here, we review general arguments for the importance of selection at levels above that of organisms in evolution, and develop them further for a common genomic feature: the carriage of transposable elements (TEs). In many species, not least our own, TEs comprise a large fraction of all nuclear DNA, and whether they individually or collectively contribute to fitness--or are instead junk--is a subject of ongoing contestation. Even if TEs generally owe their origin to selfish selection at the lowest level (that of genomes), their prevalence in extant organisms and the prevalence of extant organisms bearing them must also respond to selection within species (on organismal fitness) and between species (on rates of speciation and extinction). At an even higher level, the persistence of clades may be affected (positively or negatively) by TE carriage. If indeed TEs speed evolution, it is at these higher levels of selection that such a function might best be attributed to them as a class. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  13. From Ends to Causes (and Back Again) by Metaphor: The Paradox of Natural Selection

    Science.gov (United States)

    Blancke, Stefaan; Schellens, Tammy; Soetaert, Ronald; Van Keer, Hilde; Braeckman, Johan

    2014-01-01

    Natural selection is one of the most famous metaphors in the history of science. Charles Darwin used the metaphor and the underlying analogy to frame his ideas about evolution and its main driving mechanism into a full-fledged theory. Because the metaphor turned out to be such a powerful epistemic tool, Darwin naturally assumed that he could also…

  14. Naturally seeded versus planted ponderosa pine seedlings in group-selection openings

    Science.gov (United States)

    Philip M. McDonald; Gary Fiddler; Martin Ritchie; Paula Anderson

    2009-01-01

    The purpose of this article was to determine whether natural regeneration or planted seedlings should be used in group-selection openings. The answer dependson the survival and growth rate of both types of seedlings, and that could depend on the size of the openings and the effect of trees on their edge. In thisside-by-side study, the natural pine seedlings originated...

  15. Notice of release of Amethyst Germplasm hoaty tansyaster: Selected class of natural germplasm

    Science.gov (United States)

    Derek J. Tilley

    2015-01-01

    The US Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS), Aberdeen Plant Materials Center, Aberdeen, Idaho, announces the release of Amethyst Germplasm hoary tansyaster (Machaeronthero canescens (Pursh) A. Gray [Asteraceae]}, a selected class natural track germplasm identified by NRCS accession number 9076670 for conservation plantings in...

  16. Preimage Selective Trapdoor Function: How to Repair an Easy Problem

    Directory of Open Access Journals (Sweden)

    Baocang Wang

    2014-01-01

    Full Text Available Public key cryptosystems are constructed by embedding a trapdoor into a one-way function. So, the one-wayness and the trapdoorness are vital to public key cryptography. In this paper, we propose a novel public key cryptographic primitive called preimage selective trapdoor function. This scenario allows to use exponentially many preimage to hide a plaintext even if the underlying function is not one-way. The compact knapsack problem is used to construct a probabilistic public key cryptosystem, the underlying encryption function of which is proven to be preimage selective trapdoor one-way functions under some linearization attack models. The constructive method can guarantee the noninjectivity of the underlying encryption function and the unique decipherability for ciphertexts simultaneously. It is heuristically argued that the security of the proposal cannot be compromised by a polynomial-time adversary even if the compact knapsack is easy to solve. We failed to provide any provable security results about the proposal; however, heuristic illustrations show that the proposal is secure against some known attacks including brute force attacks, linearization attacks, and key-recovery attacks. The proposal turns out to have acceptable key sizes and performs efficiently and hence is practical.

  17. Response to selection under controlled environment versus natural selection in diverse regions across Canada

    Science.gov (United States)

    Red clover is a widely adaptable and productive forage legume species found in most temperate regions of the world. To date, specific selection techniques for identifying genotypes with superior persistence have not been successful in improving the general adaptation and the long-term persistence o...

  18. An analysis of phenotypic selection in natural stands of northern red oak (Quercus rubra L.)

    Science.gov (United States)

    Jeffery W. Stringer; David B. Wagner; Scott E. Schlarbaum; Daniel B. Houston

    1995-01-01

    Comparison of growth and stem quality parameters of 19-year-old progeny from superior and comparison trees indicates that rigorous phenotypic selection of trees in natural stands may not be an efficient method of parent tree selection for Quercus rubra L. Total tree height, dbh, number of branches in the butt log, fork height, and number of mainstem...

  19. Thoughts Toward a Theory of Natural Selection: The Importance of Microbial Experimental Evolution.

    Science.gov (United States)

    Dykhuizen, Daniel

    2016-01-08

    Natural selection should no longer be thought of simply as a primitive (magical) concept that can be used to support all kinds of evolutionary theorizing. We need to develop causal theories of natural selection; how it arises. Because the factors contributing to the creation of natural selection are expected to be complex and intertwined, theories explaining the causes of natural selection can only be developed through the experimental method. Microbial experimental evolution provides many benefits that using other organisms does not. Microorganisms are small, so millions can be housed in a test tube; they have short generation times, so evolution over hundreds of generations can be easily studied; they can grow in chemically defined media, so the environment can be precisely defined; and they can be frozen, so the fitness of strains or populations can be directly compared across time. Microbial evolution experiments can be divided into two types. The first is to measure the selection coefficient of two known strains over the first 50 or so generations, before advantageous mutations rise to high frequency. This type of experiment can be used to directly test hypotheses. The second is to allow microbial cultures to evolve over many hundreds or thousands of generations and follow the genetic changes, to infer what phenotypes are selected. In the last section of this article, I propose that selection coefficients are not constant, but change as the population becomes fitter, introducing the idea of the selection space. Copyright © 2016 Cold Spring Harbor Laboratory Press; all rights reserved.

  20. Representations of Nature of Science in Selected Histories of Science in

    Science.gov (United States)

    Wei, Bing; Li, Yue; Chen, Bo

    2013-01-01

    This study aimed to examine the representations of nature of science (NOS) in the eight histories of science selected from three series of integrated science textbooks used in junior high school in China. Ten aspects of NOS were adopted in the analytical framework. It was found that NOS had not been well treated in the selected histories of…

  1. The basic science and mathematics of random mutation and natural selection.

    Science.gov (United States)

    Kleinman, Alan

    2014-12-20

    The mutation and natural selection phenomenon can and often does cause the failure of antimicrobial, herbicidal, pesticide and cancer treatments selection pressures. This phenomenon operates in a mathematically predictable behavior, which when understood leads to approaches to reduce and prevent the failure of the use of these selection pressures. The mathematical behavior of mutation and selection is derived using the principles given by probability theory. The derivation of the equations describing the mutation and selection phenomenon is carried out in the context of an empirical example. Copyright © 2014 John Wiley & Sons, Ltd.

  2. The Nature and Functions of European Political Borders

    Directory of Open Access Journals (Sweden)

    Jernej Zupančič

    2008-07-01

    Full Text Available The political border limits a state’s territory and symbolizes the extent of a state’s power and ownership. Borders give integrity to the inner state territory which they enclose (the role of establishing national integrity and at the same time form an outer boundary segregating the state territory from the surrounding politicial entities (the segregation role. European borders are old and reflect the political history of an old continent. The last major border changes happened after World War II. Over the centuries borders were merely lines separating one territory from another. Such borders were understood as »frontiers«. Forming an effective barrier against enemies was the overriding function of borders. Many borders were fortified and further enhanced by means of various defensive systems. In the second half of the 20th century the character of political borders changed. They became a contact area between countries, nations and cultures. Contemporary European borders reflect the colourful history of an old continent. They are predominantely functional markers: they represent the political and juridical delimitation of territories, they mark economic barriers and show their defensive nature and reveal the extent of cultural contact. As a result of European integration processes, the nature of political borders has changed: instead of division, their integration role is brought to the fore. A united Europe is nevertheless still not a borderless Europe! The borders within the »Schengen-area« have retained their political and administrative functions, it is just that the customs and security checks at the borders have been removed. During the period of European integration, borderlines were stabilized in accordance with the 1974 Helsinki Agreement. But despite this we can still observe ongoing changes to state borders, particularly in areas of conflict such as the Balkan peninsula. It seems after all that the process of demarcation

  3. Natural material adsorbed onto a polymer to enhance immune function

    Directory of Open Access Journals (Sweden)

    Reinaque AP

    2012-08-01

    Full Text Available Ana Paula Barcelos Reinaque,1 Eduardo Luzía França,2 Edson Fredulin Scherer,3 Mayra Aparecida Côrtes,1 Francisco José Dutra Souto,4 Adenilda Cristina Honorio-França51Post Graduate Program in Material Science, 2Institute of Biological and Health Science, Federal University of Mato Grosso, Barra do Garças, 3Post Graduate Program in Material Science, Institute of Biological and Health Science, Federal University of Mato Grosso, Pontal do Araguaia, 4Faculty of Medical Sciences, Federal University of Mato Grosso, Cuiabá, 5Institute of Biological and Health Science, Federal University of Mato Grosso, Pontal do Araguaia, MT, BrazilBackground: In this study, we produced poly(ethylene glycol (PEG microspheres of different sizes and adsorbing a medicinal plant mixture, and verified their effect in vitro on the viability, superoxide production, and bactericidal activity of phagocytes in the blood.Methods: The medicinal plant mixture was adsorbed onto PEG microspheres and its effects were evaluated by flow cytometry and fluorescence microscopy.Results: Adsorption of the herbal mixture onto the PEG microspheres was achieved and the particles were internalized by phagocytes. PEG microspheres bearing the adsorbed herbal mixture stimulated superoxide release, and activated scavenging and microbicidal activity in phagocytes. No differences in functional activity were observed when the phagocytes were not incubated with PEG microspheres bearing the adsorbed herbal mixture.Conclusion: This system may be useful for the delivery of a variety of medicinal plants and can confer additional protection against infection. The data reported here suggest that a polymer adsorbed with a natural product is a treatment alternative for enhancing immune function.Keywords: natural product, polymer, adsorption, immune function, phagocytes

  4. The paradoxical advantages and disadvantages of natural selection: the case history of Charles Darwin.

    Science.gov (United States)

    Lieb, J

    2007-01-01

    The biology of natural selection is an enduring mystery, as is the nature of Charles Darwin's chronic illness. Of the theories advanced to explain the latter, Oedipal conflicts and Chagas' disease are preeminent. Hypomania, however, propelled Darwin to the pinnacle of scientific achievement and good health, the depression that followed condemning him to intellectual stagnation, lethargy, impaired memory and concentration, and incapacitating gastrointestinal disorders. Examples of natural selection in humans are much sought after when, ironically, one need look no further than Darwin himself.

  5. Functionally Selective AT(1) Receptor Activation Reduces Ischemia Reperfusion Injury

    DEFF Research Database (Denmark)

    Hostrup, Anders; Christensen, Gitte Lund; Bentzen, Bo Hjort

    2012-01-01

    of the physiological functions of AngII. The AT(1)R mediates its effects through both G protein-dependent and independent signaling, which can be separated by functionally selective agonists. In the present study we investigate the effect of AngII and the ß-arrestin biased agonist [SII]AngII on ischemia......]AngII had a protective effect. Together these results demonstrate a cardioprotective effect of simultaneous blockade of G protein signaling and activation of G protein independent signaling through AT(1 )receptors....

  6. Natural selection affects multiple aspects of genetic variation at putatively neutral sites across the human genome.

    Science.gov (United States)

    Lohmueller, Kirk E; Albrechtsen, Anders; Li, Yingrui; Kim, Su Yeon; Korneliussen, Thorfinn; Vinckenbosch, Nicolas; Tian, Geng; Huerta-Sanchez, Emilia; Feder, Alison F; Grarup, Niels; Jørgensen, Torben; Jiang, Tao; Witte, Daniel R; Sandbæk, Annelli; Hellmann, Ines; Lauritzen, Torsten; Hansen, Torben; Pedersen, Oluf; Wang, Jun; Nielsen, Rasmus

    2011-10-01

    A major question in evolutionary biology is how natural selection has shaped patterns of genetic variation across the human genome. Previous work has documented a reduction in genetic diversity in regions of the genome with low recombination rates. However, it is unclear whether other summaries of genetic variation, like allele frequencies, are also correlated with recombination rate and whether these correlations can be explained solely by negative selection against deleterious mutations or whether positive selection acting on favorable alleles is also required. Here we attempt to address these questions by analyzing three different genome-wide resequencing datasets from European individuals. We document several significant correlations between different genomic features. In particular, we find that average minor allele frequency and diversity are reduced in regions of low recombination and that human diversity, human-chimp divergence, and average minor allele frequency are reduced near genes. Population genetic simulations show that either positive natural selection acting on favorable mutations or negative natural selection acting against deleterious mutations can explain these correlations. However, models with strong positive selection on nonsynonymous mutations and little negative selection predict a stronger negative correlation between neutral diversity and nonsynonymous divergence than observed in the actual data, supporting the importance of negative, rather than positive, selection throughout the genome. Further, we show that the widespread presence of weakly deleterious alleles, rather than a small number of strongly positively selected mutations, is responsible for the correlation between neutral genetic diversity and recombination rate. This work suggests that natural selection has affected multiple aspects of linked neutral variation throughout the human genome and that positive selection is not required to explain these observations.

  7. Natural and sexual selection giveth and taketh away reproductive barriers: models of population divergence in guppies.

    Science.gov (United States)

    Labonne, Jacques; Hendry, Andrew P

    2010-07-01

    The standard predictions of ecological speciation might be nuanced by the interaction between natural and sexual selection. We investigated this hypothesis with an individual-based model tailored to the biology of guppies (Poecilia reticulata). We specifically modeled the situation where a high-predation population below a waterfall colonizes a low-predation population above a waterfall. Focusing on the evolution of male color, we confirm that divergent selection causes the appreciable evolution of male color within 20 generations. The rate and magnitude of this divergence were reduced when dispersal rates were high and when female choice did not differ between environments. Adaptive divergence was always coupled to the evolution of two reproductive barriers: viability selection against immigrants and hybrids. Different types of sexual selection, however, led to contrasting results for another potential reproductive barrier: mating success of immigrants. In some cases, the effects of natural and sexual selection offset each other, leading to no overall reproductive isolation despite strong adaptive divergence. Sexual selection acting through female choice can thus strongly modify the effects of divergent natural selection and thereby alter the standard predictions of ecological speciation. We also found that under no circumstances did divergent selection cause appreciable divergence in neutral genetic markers.

  8. Aberrant Time to Most Recent Common Ancestor as a Signature of Natural Selection.

    Science.gov (United States)

    Hunter-Zinck, Haley; Clark, Andrew G

    2015-10-01

    Natural selection inference methods often target one mode of selection of a particular age and strength. However, detecting multiple modes simultaneously, or with atypical representations, would be advantageous for understanding a population's evolutionary history. We have developed an anomaly detection algorithm using distributions of pairwise time to most recent common ancestor (TMRCA) to simultaneously detect multiple modes of natural selection in whole-genome sequences. As natural selection distorts local genealogies in distinct ways, the method uses pairwise TMRCA distributions, which approximate genealogies at a nonrecombining locus, to detect distortions without targeting a specific mode of selection. We evaluate the performance of our method, TSel, for both positive and balancing selection over different time-scales and selection strengths and compare TSel's performance with that of other methods. We then apply TSel to the Complete Genomics diversity panel, a set of human whole-genome sequences, and recover loci previously inferred to be under positive or balancing selection. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. Material selection for Multi-Function Waste Tank Facility tanks

    International Nuclear Information System (INIS)

    Carlos, W.C.

    1994-01-01

    This report briefly summarizes the history of the materials selection for the US Department of Energy's high-level waste carbon steel storage tanks. It also provide an evaluation of the materials for the construction of new tanks at the Multi-Function Waste Tank Facility. The evaluation included a materials matrix that summarized the critical design, fabrication, construction, and corrosion resistance requirements; assessed each requirement; and cataloged the advantages and disadvantages of each material. This evaluation is based on the mission of the Multi-Function Waste Tank Facility. On the basis of the compositions of the wastes stored in Hanford waste tanks, it is recommended that tanks for the Multi-Function Waste Tank Facility be constructed of normalized ASME SA 516, Grade 70, carbon steel

  10. Natural Microbial Assemblages Reflect Distinct Organismal and Functional Partitioning

    Science.gov (United States)

    Wilmes, P.; Andersson, A.; Kalnejais, L. H.; Verberkmoes, N. C.; Lefsrud, M. G.; Wexler, M.; Singer, S. W.; Shah, M.; Bond, P. L.; Thelen, M. P.; Hettich, R. L.; Banfield, J. F.

    2007-12-01

    The ability to link microbial community structure to function has long been a primary focus of environmental microbiology. With the advent of community genomic and proteomic techniques, along with advances in microscopic imaging techniques, it is now possible to gain insights into the organismal and functional makeup of microbial communities. Biofilms growing within highly acidic solutions inside the Richmond Mine (Iron Mountain, Redding, California) exhibit distinct macro- and microscopic morphologies. They are composed of microorganisms belonging to the three domains of life, including archaea, bacteria and eukarya. The proportion of each organismal type depends on sampling location and developmental stage. For example, mature biofilms floating on top of acid mine drainage (AMD) pools exhibit layers consisting of a densely packed bottom layer of the chemoautolithotroph Leptospirillum group II, a less dense top layer composed mainly of archaea, and fungal filaments spanning across the entire biofilm. The expression of cytochrome 579 (the most highly abundant protein in the biofilm, believed to be central to iron oxidation and encoded by Leptospirillum group II) is localized at the interface of the biofilm with the AMD solution, highlighting that biofilm architecture is reflected at the functional gene expression level. Distinct functional partitioning is also apparent in a biological wastewater treatment system that selects for distinct polyphosphate accumulating organisms. Community genomic data from " Candidatus Accumulibacter phosphatis" dominated activated sludge has enabled high mass-accuracy shotgun proteomics for identification of key metabolic pathways. Comprehensive genome-wide alignment of orthologous proteins suggests distinct partitioning of protein variants involved in both core-metabolism and specific metabolic pathways among the dominant population and closely related species. In addition, strain- resolved proteogenomic analysis of the AMD biofilms

  11. Maladaptive Plasticity Masks the Effects of Natural Selection in the Red-Shouldered Soapberry Bug.

    Science.gov (United States)

    Cenzer, Meredith L

    2017-10-01

    Natural selection can produce local adaptation, but local adaptation can be masked by maladaptive plasticity. Maladaptive plasticity may arise as a result of gene flow producing novel gene combinations that have not been exposed to selection. In the 1980s, populations of the red-shouldered soapberry bug (Jadera haematoloma) were locally adapted to feed on the seeds of a native host plant and an introduced host plant; by 2014, local differentiation in beak length had been lost, likely as a consequence of increased gene flow. In this study, I assess the relative contributions of natural selection and plasticity to beak length on these two hosts. I confirm the earlier hypothesis that the host plant seedpod drives divergent natural selection on beak length. I then demonstrate that the proximate cause of the loss of observable differentiation in beak length is maladaptive plasticity, which masks persistent genetic differences between host-associated populations. Maladaptive plasticity is highest in areas where the two plants co-occur; in combination with historical measures of plasticity in hybrids, this indicates that maladaptive plasticity may be a consequence of ongoing gene flow. Although natural selection produced locally adapted genotypes in soapberry bugs, maladaptive plasticity is masking phenotypic differences between populations in nature.

  12. Cholesterol overload impairing cerebellar function: the promise of natural products.

    Science.gov (United States)

    El-Sayyad, Hassan I H

    2015-05-01

    The cerebellum is the part of the brain most involved in controlling motor and cognitive function. The surface becomes convoluted, forming folia that have a characteristic internal structure of three layers including molecular, Purkinje cell, and granular layer. This complex neural network gives rise to a massive signal-processing capability. Cholesterol is a major constituent, derived by de novo synthesis and the blood-brain barrier. Cholesterol is tightly regulated between neurons and glia-that is, astrocytes, microglia, and oligodendrocytes-and is essential for normal brain development. The axon is wrapped by myelin (cholesterol, phospholipids, and glycosphingolipids) and made up of membranes of oligodendrocytes, separated by periodic gaps in the myelin sheath, called nodes of Ranvier. Hypercholesterolemia is associated with increased oxidative stress and the development of neurotoxicity and Alzheimer's disease. Treatment with natural products has been found to support improved brain function and reduce low-density-lipoprotein cholesterol level. Fish oil is one such product; among the many plant products are: Morus alba leaves, fruit, and bark; pomegranate fruit and peel; Barley β - glucans; date palm; and Allium sativum. The therapeutic potential was discussed in relation with the antilipidemic drugs, statins (HMG-CoA reductase inhibitors). Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Consumers control diversity and functioning of a natural marine ecosystem.

    Directory of Open Access Journals (Sweden)

    Andrew H Altieri

    Full Text Available BACKGROUND: Our understanding of the functional consequences of changes in biodiversity has been hampered by several limitations of previous work, including limited attention to trophic interactions, a focus on species richness rather than evenness, and the use of artificially assembled communities. METHODOLOGY AND PRINCIPAL FINDINGS: In this study, we manipulated the density of an herbivorous snail in natural tide pools and allowed seaweed communities to assemble in an ecologically relevant and non-random manner. Seaweed species evenness and biomass-specific primary productivity (mg O(2 h(-1 g(-1 were higher in tide pools with snails because snails preferentially consumed an otherwise dominant seaweed species that can reduce biomass-specific productivity rates of algal assemblages. Although snails reduced overall seaweed biomass in tide pools, they did not affect gross primary productivity at the scale of tide pools (mg O(2 h(-1 pool(-1 or mg O(2 h(-1 m(-2 because of the enhanced biomass-specific productivity associated with grazer-mediated increases in algal evenness. SIGNIFICANCE: Our results suggest that increased attention to trophic interactions, diversity measures other than richness, and particularly the effects of consumers on evenness and primary productivity, will improve our understanding of the relationship between diversity and ecosystem functioning and allow more effective links between experimental results and real-world changes in biodiversity.

  14. Estimation of cost function in the natural gas industry

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Duk [Korea Energy Economics Institute, Euiwang (Korea)

    1999-02-01

    The natural gas industry in Korea has characteristics of a dual industrial structure with wholesale and retail and a regional monopoly of city gas company. Recently there have been discussions on the restructuring of gas industry and the problems arising from such industrial organization. At this point, the labor and capital cost of KOGAS were analyzed to find out efficiency of KOGAS, the wholesaler and the cost function focusing on distribution was estimated to find out effect of scale of city gas company, the retailer. As a result, in the case of KOGAS, it is prove that enhancing competitive power is needed by improving labor productivity through stabilization of labor structure and by maximizing value-added through stability of capital combination. From the estimation of cost function of city gas companies, the existing regional monopoly of city gas company have effects on its scale only when the area of operation and end users used the same amount per end user are increased. (author). 31 refs., 10 figs., 43 tabs.

  15. Genetic evidence for natural selection in humans in the contemporary United States.

    Science.gov (United States)

    Beauchamp, Jonathan P

    2016-07-12

    Recent findings from molecular genetics now make it possible to test directly for natural selection by analyzing whether genetic variants associated with various phenotypes have been under selection. I leverage these findings to construct polygenic scores that use individuals' genotypes to predict their body mass index, educational attainment (EA), glucose concentration, height, schizophrenia, total cholesterol, and (in females) age at menarche. I then examine associations between these scores and fitness to test whether natural selection has been occurring. My study sample includes individuals of European ancestry born between 1931 and 1953 who participated in the Health and Retirement Study, a representative study of the US population. My results imply that natural selection has been slowly favoring lower EA in both females and males, and are suggestive that natural selection may have favored a higher age at menarche in females. For EA, my estimates imply a rate of selection of about -1.5 mo of education per generation (which pales in comparison with the increases in EA observed in contemporary times). Although they cannot be projected over more than one generation, my results provide additional evidence that humans are still evolving-albeit slowly, especially compared with the rapid changes that have occurred over the past few generations due to cultural and environmental factors.

  16. High-performance intrinsically microporous dihydroxyl-functionalized triptycene-based polyimide for natural gas separation

    KAUST Repository

    Alaslai, Nasser Y.; Ghanem, Bader; Alghunaimi, Fahd; Pinnau, Ingo

    2016-01-01

    A novel polyimide of intrinsic microporosity (PIM-PI) was synthesized from a 9,10-diisopropyl-triptycene-based dianhydride (TPDA) and dihydroxyl-functionalized 4,6-diaminoresorcinol (DAR). The unfunctionalized TPDA-m-phenylenediamine (mPDA) polyimide derivative was made as a reference material to evaluate the effect of the OH group in TPDA-DAR on its gas transport properties. Pure-gas permeability coefficients of He, H2, N2, O2, CH4, and CO2 were measured at 35 °C and 2 atm. The BET surface area based on nitrogen adsorption of dihydroxyl-functionalized TPDA-DAR (308 m2g-1) was 45% lower than that of TPDA-mPDA (565 m2g-1). TPDA-mPDA had a pure-gas CO2 permeability of 349 Barrer and CO2/CH4 selectivity of 32. The dihydroxyl-functionalized TPDA-DAR polyimide exhibited enhanced pure-gas CO2/CH4 selectivity of 46 with a moderate decrease in CO2 permeability to 215 Barrer. The CO2 permeability of TPDA-DAR was ∼30-fold higher than that of a commercial cellulose triacetate membrane coupled with 39% higher pure-gas CO2/CH4 selectivity. The TPDA-based dihydroxyl-containing polyimide showed good plasticization resistance and maintained high mixed-gas selectivity of 38 when tested at a typical CO2 natural gas wellhead CO2 partial pressure of 10 atm.

  17. High-performance intrinsically microporous dihydroxyl-functionalized triptycene-based polyimide for natural gas separation

    KAUST Repository

    Alaslai, Nasser Y.

    2016-03-22

    A novel polyimide of intrinsic microporosity (PIM-PI) was synthesized from a 9,10-diisopropyl-triptycene-based dianhydride (TPDA) and dihydroxyl-functionalized 4,6-diaminoresorcinol (DAR). The unfunctionalized TPDA-m-phenylenediamine (mPDA) polyimide derivative was made as a reference material to evaluate the effect of the OH group in TPDA-DAR on its gas transport properties. Pure-gas permeability coefficients of He, H2, N2, O2, CH4, and CO2 were measured at 35 °C and 2 atm. The BET surface area based on nitrogen adsorption of dihydroxyl-functionalized TPDA-DAR (308 m2g-1) was 45% lower than that of TPDA-mPDA (565 m2g-1). TPDA-mPDA had a pure-gas CO2 permeability of 349 Barrer and CO2/CH4 selectivity of 32. The dihydroxyl-functionalized TPDA-DAR polyimide exhibited enhanced pure-gas CO2/CH4 selectivity of 46 with a moderate decrease in CO2 permeability to 215 Barrer. The CO2 permeability of TPDA-DAR was ∼30-fold higher than that of a commercial cellulose triacetate membrane coupled with 39% higher pure-gas CO2/CH4 selectivity. The TPDA-based dihydroxyl-containing polyimide showed good plasticization resistance and maintained high mixed-gas selectivity of 38 when tested at a typical CO2 natural gas wellhead CO2 partial pressure of 10 atm.

  18. Spent yeast as natural source of functional food additives

    Science.gov (United States)

    Rakowska, Rita; Sadowska, Anna; Dybkowska, Ewa; Świderski, Franciszek

    as natural food additives that are functional.

  19. Selective Aptamers for Detection of Estradiol and Ethynylestradiol in Natural Waters

    KAUST Repository

    Akki, Spurti U.; Werth, Charles J.; Silverman, Scott K.

    2015-01-01

    © 2015 American Chemical Society. We used in vitro selection to identify new DNA aptamers for two endocrine-disrupting compounds often found in treated and natural waters, 17β-estradiol (E2) and 17α-ethynylestradiol (EE). We used equilibrium filtration to determine aptamer sensitivity/selectivity and dimethyl sulfate (DMS) probing to explore aptamer binding sites. The new E2 aptamers are at least 74-fold more sensitive for E2 than is a previously reported DNA aptamer, with dissociation constants (Kd values) of 0.6 μM. Similarly, the EE aptamers are highly sensitive for EE, with Kd of 0.5-1.0 μM. Selectivity values indicate that the E2 aptamers bind E2 and a structural analogue, estrone (E1), equally well and are up to 74-fold selective over EE. One EE aptamer is 53-fold more selective for EE over E2 or E1, but the other binds EE, E2, and E1 with similar affinity. The new aptamers do not lose sensitivity or selectivity in natural water from a local lake, despite the presence of natural organic matter (∼4 mg/L TOC). DMS probing suggests that E2 binding occurs in relatively flexible single-stranded DNA regions, an important finding for rational redesign of aptamers and their incorporation into sensing platforms. This is the first report of aptamers with strong selectivity for E2 and E1 over EE, or with strong selectivity for EE over E2 and E1. Such selectivity is important for achieving the goal of creating practically useful DNA-based sensors that can distinguish structurally similar estrogenic compounds in natural waters.

  20. Selective Aptamers for Detection of Estradiol and Ethynylestradiol in Natural Waters

    KAUST Repository

    Akki, Spurti U.

    2015-08-18

    © 2015 American Chemical Society. We used in vitro selection to identify new DNA aptamers for two endocrine-disrupting compounds often found in treated and natural waters, 17β-estradiol (E2) and 17α-ethynylestradiol (EE). We used equilibrium filtration to determine aptamer sensitivity/selectivity and dimethyl sulfate (DMS) probing to explore aptamer binding sites. The new E2 aptamers are at least 74-fold more sensitive for E2 than is a previously reported DNA aptamer, with dissociation constants (Kd values) of 0.6 μM. Similarly, the EE aptamers are highly sensitive for EE, with Kd of 0.5-1.0 μM. Selectivity values indicate that the E2 aptamers bind E2 and a structural analogue, estrone (E1), equally well and are up to 74-fold selective over EE. One EE aptamer is 53-fold more selective for EE over E2 or E1, but the other binds EE, E2, and E1 with similar affinity. The new aptamers do not lose sensitivity or selectivity in natural water from a local lake, despite the presence of natural organic matter (∼4 mg/L TOC). DMS probing suggests that E2 binding occurs in relatively flexible single-stranded DNA regions, an important finding for rational redesign of aptamers and their incorporation into sensing platforms. This is the first report of aptamers with strong selectivity for E2 and E1 over EE, or with strong selectivity for EE over E2 and E1. Such selectivity is important for achieving the goal of creating practically useful DNA-based sensors that can distinguish structurally similar estrogenic compounds in natural waters.

  1. Natural selection affects multiple aspects of genetic variation at putatively peutral sites across the human genome

    DEFF Research Database (Denmark)

    Lohmueller, Kirk E; Albrechtsen, Anders; Li, Yingrui

    2011-01-01

    A major question in evolutionary biology is how natural selection has shaped patterns of genetic variation across the human genome. Previous work has documented a reduction in genetic diversity in regions of the genome with low recombination rates. However, it is unclear whether other summaries...... these questions by analyzing three different genome-wide resequencing datasets from European individuals. We document several significant correlations between different genomic features. In particular, we find that average minor allele frequency and diversity are reduced in regions of low recombination...... and that human diversity, human-chimp divergence, and average minor allele frequency are reduced near genes. Population genetic simulations show that either positive natural selection acting on favorable mutations or negative natural selection acting against deleterious mutations can explain these correlations...

  2. Selective Androgen Receptor Modulators (SARMs) as Function Promoting Therapies

    Science.gov (United States)

    Bhasin, Shalender; Jasuja, Ravi

    2010-01-01

    Purpose of review The last decade has witnessed unprecedented discovery effort to develop selective androgen receptor modulators (SARMs) that improve physical function and bone health without adversely affecting the prostate and cardiovascular outcomes. This review describes the historical evolution, the rationale for SARM development, and the mechanisms of testosterone action and SARM selectivity. Recent Findings While steroidal SARMs have been around since the 1940s, a number of nonsteroidal SARMs that do not serve as substrates for CYP19 aromatase or 5α-reductase, act as full agonists in muscle and bone and as partial agonists in prostate are in development. The differing interactions of steroidal and nonsteroidal compounds with AR contribute to their unique pharmacologic actions. Ligand binding induces specific conformational changes in the ligand binding domain, which could modulate surface topology and protein-protein interactions between AR and coregulators, resulting in tissue-specific gene regulation. Preclinical studies have demonstrated the ability of SARMs to increase muscle and bone mass in preclinical rodent models with varying degree of prostate sparing. Phase I trials of SARMs in humans have reported modest increments in fat-free mass. Summary SARMs hold promise as a new class of function promoting anabolic therapies for a number of clinical indications, including functional limitations associated with aging and chronic disease, frailty, cancer cachexia, and osteoporosis. PMID:19357508

  3. Selective androgen receptor modulators as function promoting therapies.

    Science.gov (United States)

    Bhasin, Shalender; Jasuja, Ravi

    2009-05-01

    The past decade has witnessed an unprecedented discovery effort to develop selective androgen receptor modulators (SARMs) that improve physical function and bone health without adversely affecting the prostate and cardiovascular outcomes. This review describes the historical evolution, the rationale for SARM development, and the mechanisms of testosterone action and SARM selectivity. Although steroidal SARMs have been around since the 1940s, a number of nonsteroidal SARMs that do not serve as substrates for CYP19 aromatase or 5alpha-reductase, act as full agonists in muscle and bone and as partial agonists in prostate are in development. The differing interactions of steroidal and nonsteroidal compounds with androgen receptor (AR) contribute to their unique pharmacologic actions. Ligand binding induces specific conformational changes in the ligand-binding domain, which could modulate surface topology and protein-protein interactions between AR and coregulators, resulting in tissue-specific gene regulation. Preclinical studies have demonstrated the ability of SARMs to increase muscle and bone mass in preclinical rodent models with varying degree of prostate sparing. Phase I trials of SARMs in humans have reported modest increments in fat-free mass. SARMs hold promise as a new class of function promoting anabolic therapies for a number of clinical indications, including functional limitations associated with aging and chronic disease, frailty, cancer cachexia, and osteoporosis.

  4. Using natural selection and optimization for smarter vegetation models - challenges and opportunities

    Science.gov (United States)

    Franklin, Oskar; Han, Wang; Dieckmann, Ulf; Cramer, Wolfgang; Brännström, Åke; Pietsch, Stephan; Rovenskaya, Elena; Prentice, Iain Colin

    2017-04-01

    Dynamic global vegetation models (DGVMs) are now indispensable for understanding the biosphere and for estimating the capacity of ecosystems to provide services. The models are continuously developed to include an increasing number of processes and to utilize the growing amounts of observed data becoming available. However, while the versatility of the models is increasing as new processes and variables are added, their accuracy suffers from the accumulation of uncertainty, especially in the absence of overarching principles controlling their concerted behaviour. We have initiated a collaborative working group to address this problem based on a 'missing law' - adaptation and optimization principles rooted in natural selection. Even though this 'missing law' constrains relationships between traits, and therefore can vastly reduce the number of uncertain parameters in ecosystem models, it has rarely been applied to DGVMs. Our recent research have shown that optimization- and trait-based models of gross primary production can be both much simpler and more accurate than current models based on fixed functional types, and that observed plant carbon allocations and distributions of plant functional traits are predictable with eco-evolutionary models. While there are also many other examples of the usefulness of these and other theoretical principles, it is not always straight-forward to make them operational in predictive models. In particular on longer time scales, the representation of functional diversity and the dynamical interactions among individuals and species presents a formidable challenge. Here we will present recent ideas on the use of adaptation and optimization principles in vegetation models, including examples of promising developments, but also limitations of the principles and some key challenges.

  5. Cell-selective metabolic labeling of biomolecules with bioorthogonal functionalities.

    Science.gov (United States)

    Xie, Ran; Hong, Senlian; Chen, Xing

    2013-10-01

    Metabolic labeling of biomolecules with bioorthogonal functionalities enables visualization, enrichment, and analysis of the biomolecules of interest in their physiological environments. This versatile strategy has found utility in probing various classes of biomolecules in a broad range of biological processes. On the other hand, metabolic labeling is nonselective with respect to cell type, which imposes limitations for studies performed in complex biological systems. Herein, we review the recent methodological developments aiming to endow metabolic labeling strategies with cell-type selectivity. The cell-selective metabolic labeling strategies have emerged from protein and glycan labeling. We envision that these strategies can be readily extended to labeling of other classes of biomolecules. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Aripiprazole, A Drug that Displays Partial Agonism and Functional Selectivity.

    Science.gov (United States)

    Tuplin, Erin W; Holahan, Matthew R

    2017-11-14

    The treatment of schizophrenia is challenging due to the wide range of symptoms (positive, negative, cognitive) associated with the disease. Typical antipsychotics that antagonize D2 receptors are effective in treating positive symptoms, but extrapyramidal side-effects (EPS) are a common occurrence. Atypical antipsychotics targeting 5-HT2A and D2 receptors are more effective at treating cognitive and negative symptoms compared to typical antipsychotics, but these drugs also result in side-effects such as metabolic syndromes. To identify evidence in the literature that elucidates the pharmacological profile of aripiprazole.s. We searched PubMed for peer reviewed articles on aripiprazole and its clinical efficacy, side-effects, pharmacology, and effects in animal models of schizophrenia symptoms. Aripiprazole is a newer atypical antipsychotic that displays a unique pharmacological profile, including partial D2 agonism and functionally selective properties. Aripiprazole is effective at treating the positive symptoms of schizophrenia and has the potential to treat negative and cognitive symptoms at least as well as other atypical antipsychotics. The drug has a favorable side-effect profile and has a low propensity to result in EPS or metabolic syndromes. Animal models of schizophrenia have been used to determine the efficacy of aripiprazole in symptom management. In these instances, aripiprazole resulted in the reversal of deficits in extinction, pre-pulse inhibition, and social withdrawal. Because aripiprazole requires a greater than 90% occupancy rate at D2 receptors to be clinically active and does not produce EPS, this suggests a functionally selective effect on intracellular signaling pathways. A combination of factors such as dopamine system stabilization via partial agonism, functional selectivity at D2 receptors, and serotonin-dopamine system interaction may contribute to the ability of aripiprazole to successfully manage schizophrenia symptoms. This review

  7. Maintenance of a genetic polymorphism with disruptive natural selection in stickleback.

    Science.gov (United States)

    Marchinko, Kerry B; Matthews, Blake; Arnegard, Matthew E; Rogers, Sean M; Schluter, Dolph

    2014-06-02

    The role of natural selection in the maintenance of genetic variation in wild populations remains a major problem in evolution. The influence of disruptive natural selection on genetic variation is especially interesting because it might lead to the evolution of assortative mating or dominance [1, 2]. In theory, variation can persist at a gene under disruptive natural selection, but the process is little studied and there are few examples [3, 4]. We report a stable polymorphism in the bony armor of threespine stickleback maintained with a deficit of heterozygotes at the major underlying gene, Ectodysplasin (Eda) [5]. The deficit vanishes at the embryo life stage only to re-emerge in adults, indicating that disruptive natural selection, rather than nonrandom mating, is the cause. The mechanism enabling long-term persistence of the polymorphism is unknown, but disruptive selection is predicted to be frequency dependent, favoring homozygous genotypes when they become rare. Further research on the ecological and evolutionary processes affecting individual genes will ultimately lead to a better understanding of the causes of genetic variation in populations. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Electrocatalytic Activity and Selectivity - a Density Functional Theory Study

    DEFF Research Database (Denmark)

    Karamad, Mohammadreza

    -catalysts towards two appealing electrochemical reactions: 1)electroreduction of CO2 to hydrocarbons and alcohols, and 2) electrochemical production of hydrogen peroxide, i.e. H2O2, from its elements i.e. H2 and O2. The thesis is divided into three parts: In the first part, electro-catalytic activity of different...... metallic and functionalized graphene catalysts. Secondly, we considered CO2 reduction on RuO2, which has a distinctive catalytic activity and selectivity compared to Cu to get insight into mechanistic pathway of the CO2 reduction. Finally, in the last part, we have taken advantage of the isolated active...

  9. Landscape genomics: natural selection drives the evolution of mitogenome in penguins

    OpenAIRE

    Ramos, Barbara; González-Acuña, Daniel; Loyola, David E.; Johnson, Warren E.; Parker, Patricia G.; Massaro, Melanie; Dantas, Gisele P. M.; Miranda, Marcelo D.; Vianna, Juliana A.

    2018-01-01

    Background Mitochondria play a key role in the balance of energy and heat production, and therefore the mitochondrial genome is under natural selection by environmental temperature and food availability, since starvation can generate more efficient coupling of energy production. However, selection over mitochondrial DNA (mtDNA) genes has usually been evaluated at the population level. We sequenced by NGS 12 mitogenomes and with four published genomes, assessed genetic variation in ten penguin...

  10. From Ends to Causes (and Back Again) by Metaphor: The Paradox of Natural Selection

    Science.gov (United States)

    Blancke, Stefaan; Schellens, Tammy; Soetaert, Ronald; Van Keer, Hilde; Braeckman, Johan

    2014-04-01

    Natural selection is one of the most famous metaphors in the history of science. Charles Darwin used the metaphor and the underlying analogy to frame his ideas about evolution and its main driving mechanism into a full-fledged theory. Because the metaphor turned out to be such a powerful epistemic tool, Darwin naturally assumed that he could also employ it as an educational tool to inform his contemporaries about his findings. Moreover, by using the metaphor Darwin was able to bring his theory in accordance with both the dominant philosophy of science in his time and the respected tradition of natural theology. However, as he introduced his theory of evolution by natural selection in On the origin of species in 1859, the metaphor also turned out to have a serious downside. Because of its intentional overtones, his contemporaries systematically misunderstood his metaphor not as a natural mechanism causing evolution to occur but as an agent who works towards particular ends. The difference in success between natural selection as an epistemic tool and its failure as an educational tool is labelled as a paradox. We explain the paradox from a cognitive perspective and discuss the implications for teaching evolution.

  11. Functional Analysis Of A Selected Airport’s System

    Directory of Open Access Journals (Sweden)

    Dudek Ewa

    2015-11-01

    Full Text Available In this paper two selected airport’s systems (Flight Information System and Public Address Voice Annunciation are defined and described. Then they are used to create an integrated unit, with the presentation of its way of functioning and a schematic picture. The author names main purposes of the integration process, serving to counteract negative consequences arising from implementation of the increasing number of systems on transport objects. In the following part of the article functional analysis of the integrated unit is carried out, defining system’s possible states of work and relations between them. Utilization of mathematical apparatus allows to calculate probabilities of system staying in the respective states, as well as system’s time indexes. Presented results are a fundament for the further analysis of this matter.

  12. Effects of the Ordering of Natural Selection and Population Regulation Mechanisms on Wright-Fisher Models.

    Science.gov (United States)

    He, Zhangyi; Beaumont, Mark; Yu, Feng

    2017-07-05

    We explore the effect of different mechanisms of natural selection on the evolution of populations for one- and two-locus systems. We compare the effect of viability and fecundity selection in the context of the Wright-Fisher model with selection under the assumption of multiplicative fitness. We show that these two modes of natural selection correspond to different orderings of the processes of population regulation and natural selection in the Wright-Fisher model. We find that under the Wright-Fisher model these two different orderings can affect the distribution of trajectories of haplotype frequencies evolving with genetic recombination. However, the difference in the distribution of trajectories is only appreciable when the population is in significant linkage disequilibrium. We find that as linkage disequilibrium decays the trajectories for the two different models rapidly become indistinguishable. We discuss the significance of these findings in terms of biological examples of viability and fecundity selection, and speculate that the effect may be significant when factors such as gene migration maintain a degree of linkage disequilibrium. Copyright © 2017 He et al.

  13. Selective oxidation of cyclohexene through gold functionalized silica monolith microreactors

    Science.gov (United States)

    Alotaibi, Mohammed T.; Taylor, Martin J.; Liu, Dan; Beaumont, Simon K.; Kyriakou, Georgios

    2016-04-01

    Two simple, reproducible methods of preparing evenly distributed Au nanoparticle containing mesoporous silica monoliths are investigated. These Au nanoparticle containing monoliths are subsequently investigated as flow reactors for the selective oxidation of cyclohexene. In the first strategy, the silica monolith was directly impregnated with Au nanoparticles during the formation of the monolith. The second approach was to pre-functionalize the monolith with thiol groups tethered within the silica mesostructure. These can act as evenly distributed anchors for the Au nanoparticles to be incorporated by flowing a Au nanoparticle solution through the thiol functionalized monolith. Both methods led to successfully achieving even distribution of Au nanoparticles along the length of the monolith as demonstrated by ICP-OES. However, the impregnation method led to strong agglomeration of the Au nanoparticles during subsequent heating steps while the thiol anchoring procedure maintained the nanoparticles in the range of 6.8 ± 1.4 nm. Both Au nanoparticle containing monoliths as well as samples with no Au incorporated were tested for the selective oxidation of cyclohexene under constant flow at 30 °C. The Au free materials were found to be catalytically inactive with Au being the minimum necessary requirement for the reaction to proceed. The impregnated Au-containing monolith was found to be less active than the thiol functionalized Au-containing material, attributable to the low metal surface area of the Au nanoparticles. The reaction on the thiol functionalized Au-containing monolith was found to depend strongly on the type of oxidant used: tert-butyl hydroperoxide (TBHP) was more active than H2O2, likely due to the thiol induced hydrophobicity in the monolith.

  14. Mathematical Physics Framework SustainingNatural Anticipation and Selection of Attention

    Directory of Open Access Journals (Sweden)

    Alfons Salden

    2005-04-01

    Full Text Available An ambient intelligent environment is definitely a prerequisite for anticipating the needs and catching the attention of systems. But how to endow such an environment with natural anticipatory and attentive features is still a hardly ever properly addressed question. Before providing a roadmap towards such an ambient intelligent environment we first give cognitive-ergonomic accounts for how natural anticipation and selection of attention (NASA emerge in living organisms. In particular, we describe why, when and how exploratory and goal-directed acts by living organisms are controlled while optimizing their changing and limited structural and functional capabilities of multimodal sensor, cognitive and actuator systems. Next, we describe how NASA can be embedded and embodied in sustainable intelligent multimodal systems (SIMS. Such systems allow an ambient intelligent environment to (self- interact taking its contexts into account. In addition, collective intelligent agents (CIA distribute, store, extend, maintain, optimize, diversify and sustain the NASA embedded and embodied in the ambient intelligent environment. Finally, we present the basic ingredients of a mathematical-physical framework for empirically modeling and sustaining NASA within SIMS by CIA in an ambient intelligent environment. An environment which is modeled this way, robustly and reliably over time aligns multi-sensor detection and fusion; multimodal fusion, dialogue planning and fission; multi actuator fission, rendering and presentation schemes. NASA residing in such an environment are then active within every phase of perception-decision-action cycles, and are gauged and renormalized to its physics. After determining and assessing across several evolutionary dynamic scales appropriate fitness, utility and measures, NASA can be realized by reinforcement learning and self-organization.

  15. Natural RNA circles function as efficient microRNA sponges

    DEFF Research Database (Denmark)

    Hansen, Thomas Birkballe; Jensen, Trine I; Clausen, Bettina Hjelm

    2013-01-01

    MicroRNAs (miRNAs) are important post-transcriptional regulators of gene expression that act by direct base pairing to target sites within untranslated regions of messenger RNAs. Recently, miRNA activity has been shown to be affected by the presence of miRNA sponge transcripts, the so-called comp......MicroRNAs (miRNAs) are important post-transcriptional regulators of gene expression that act by direct base pairing to target sites within untranslated regions of messenger RNAs. Recently, miRNA activity has been shown to be affected by the presence of miRNA sponge transcripts, the so......-called competing endogenous RNA in humans and target mimicry in plants. We previously identified a highly expressed circular RNA (circRNA) in human and mouse brain. Here we show that this circRNA acts as a miR-7 sponge; we term this circular transcript ciRS-7 (circular RNA sponge for miR-7). ciRS-7 contains more...... sponge, suggesting that miRNA sponge effects achieved by circRNA formation are a general phenomenon. This study serves as the first, to our knowledge, functional analysis of a naturally expressed circRNA....

  16. Cordyceps fungi: natural products, pharmacological functions and developmental products.

    Science.gov (United States)

    Zhou, Xuanwei; Gong, Zhenghua; Su, Ying; Lin, Juan; Tang, Kexuan

    2009-03-01

    Parasitic Cordyceps fungi, such as Cordyceps sinensis, is a parasitic complex of fungus and caterpillar, which has been used for medicinal purposes for centuries particularly in China, Japan and other Asian countries. This article gives a general idea of the latest developments in C. sinensis research, with regard to the active chemical components, the pharmacological effects and the research and development of products in recent years. The common names for preparations include DongChongXiaCao in Chinese, winter worm summer grass in English. It has many bioactive components, such as 3'-deoxyadenosine, cordycepic acid and Cordyceps polysaccharides. It is commonly used to replenish the kidney and soothe the lung, and for the treatment of fatigue. It also can be used to treat conditions such as night sweating, hyposexuality, hyperglycaemia, hyperlipidaemia, asthenia after severe illness, respiratory disease, renal dysfunction, renal failure, arrhythmias and other heart disease and liver disease. Because of its rarity and outstanding curative effects, several mycelia strains have been isolated from natural Cordyceps and manufactured by fermentation technology, and are commonly sold as health food products. In addition, some substitutes such as C. militaris and adulterants also have been used; therefore, quality control of C. sinensis and its products is very important to ensure their safety and efficacy. Recent research advances in the study of Cordyceps, including Cordyceps mushrooms, chemical components, pharmacological functions and developmental products, has been reviewed and discussed. Developing trends in the field have also been appraised.

  17. Contribution to the theory of interpretation of gamma natural selective logging and global

    International Nuclear Information System (INIS)

    Alpha, Aboubacrine.

    1982-10-01

    The gamma natural selective method allows the ''in situ'' measurement of the uranium content of ores independently of the value of the U/Ra equilibrium. The use of this methode meets two sorts of difficulties: - first, the gamma spectrum is distorted by some factors connected with the conditions of measurement: drilling mud, tubing, position of the probe in the borehole; - secondy, the interpretation of the anomaly I1 (low energy) requires the knowledge of μ1 (absorption coefficient for gamma ray) which is a function of the uranium content which is to be determined. The present work develops two original calculation methods which allow to overcome these difficulties. The principles used are mentionned hereafter. 1) It is shown that it is possible to calculate the numerical values of coefficients μ1 et μ2, without previous determination of the uranium grade, which eventually allows their calculation afterwards. 2) From the general formula of J.A. CZUBEK applying to infinite medium, a new formula applying to finite medium has been established. The formula thus obtained takes into account the measurement conditions. The last part contains an estimation of the errors allowing to specify the limits of validity of the method [fr

  18. Biological Principles and Threshold Concepts for Understanding Natural Selection. Implications for Developing Visualizations as a Pedagogic Tool

    Science.gov (United States)

    Tibell, Lena A. E.; Harms, Ute

    2017-11-01

    Modern evolutionary theory is both a central theory and an integrative framework of the life sciences. This is reflected in the common references to evolution in modern science education curricula and contexts. In fact, evolution is a core idea that is supposed to support biology learning by facilitating the organization of relevant knowledge. In addition, evolution can function as a pivotal link between concepts and highlight similarities in the complexity of biological concepts. However, empirical studies in many countries have for decades identified deficiencies in students' scientific understanding of evolution mainly focusing on natural selection. Clearly, there are major obstacles to learning natural selection, and we argue that to overcome them, it is essential to address explicitly the general abstract concepts that underlie the biological processes, e.g., randomness or probability. Hence, we propose a two-dimensional framework for analyzing and structuring teaching of natural selection. The first—purely biological—dimension embraces the three main principles variation, heredity, and selection structured in nine key concepts that form the core idea of natural selection. The second dimension encompasses four so-called thresholds, i.e., general abstract and/or non-perceptual concepts: randomness, probability, spatial scales, and temporal scales. We claim that both of these dimensions must be continuously considered, in tandem, when teaching evolution in order to allow development of a meaningful understanding of the process. Further, we suggest that making the thresholds tangible with the aid of appropriate kinds of visualizations will facilitate grasping of the threshold concepts, and thus, help learners to overcome the difficulties in understanding the central theory of life.

  19. Population genetic structure and natural selection of Plasmodium falciparum apical membrane antigen-1 in Myanmar isolates.

    Science.gov (United States)

    Kang, Jung-Mi; Lee, Jinyoung; Moe, Mya; Jun, Hojong; Lê, Hương Giang; Kim, Tae Im; Thái, Thị Lam; Sohn, Woon-Mok; Myint, Moe Kyaw; Lin, Khin; Shin, Ho-Joon; Kim, Tong-Soo; Na, Byoung-Kuk

    2018-02-07

    Plasmodium falciparum apical membrane antigen-1 (PfAMA-1) is one of leading blood stage malaria vaccine candidates. However, genetic variation and antigenic diversity identified in global PfAMA-1 are major hurdles in the development of an effective vaccine based on this antigen. In this study, genetic structure and the effect of natural selection of PfAMA-1 among Myanmar P. falciparum isolates were analysed. Blood samples were collected from 58 Myanmar patients with falciparum malaria. Full-length PfAMA-1 gene was amplified by polymerase chain reaction and cloned into a TA cloning vector. PfAMA-1 sequence of each isolate was sequenced. Polymorphic characteristics and effect of natural selection were analysed with using DNASTAR, MEGA4, and DnaSP programs. Polymorphic nature and natural selection in 459 global PfAMA-1 were also analysed. Thirty-seven different haplotypes of PfAMA-1 were identified in 58 Myanmar P. falciparum isolates. Most amino acid changes identified in Myanmar PfAMA-1 were found in domains I and III. Overall patterns of amino acid changes in Myanmar PfAMA-1 were similar to those in global PfAMA-1. However, frequencies of amino acid changes differed by country. Novel amino acid changes in Myanmar PfAMA-1 were also identified. Evidences for natural selection and recombination event were observed in global PfAMA-1. Among 51 commonly identified amino acid changes in global PfAMA-1 sequences, 43 were found in predicted RBC-binding sites, B-cell epitopes, or IUR regions. Myanmar PfAMA-1 showed similar patterns of nucleotide diversity and amino acid polymorphisms compared to those of global PfAMA-1. Balancing natural selection and intragenic recombination across PfAMA-1 are likely to play major roles in generating genetic diversity in global PfAMA-1. Most common amino acid changes in global PfAMA-1 were located in predicted B-cell epitopes where high levels of nucleotide diversity and balancing natural selection were found. These results highlight the

  20. Executive Selection in Government Agencies: An Analysis of the Department of the Navy and Immigration and Naturalization Services Senior Executive Service Selection Processes

    National Research Council Canada - National Science Library

    Jordan, Mark

    2001-01-01

    .... The Senior Executive Service (SES) selection process for the Department of the Navy (DON) is analyzed and compared to the SES selection process used by the Immigration and Naturalization Service...

  1. Functionalized membranes for environmental remediation and selective separation

    Science.gov (United States)

    Xiao, Li

    ) between UF and RO presents selectivity controlled by both steric and electrostatic repulsions, which are widely used to reject charged species, particularly multivalent ions. In this work, selective permeation of CaCl2 and high sucrose retention are obtained through the modification of nanofiltration membranes with lower charge compared to commercial nanofiltration membrane. The membrane module also shows high stability with constant water permeability in a long-term (two months) test. Extended Nernst-Planck equation were further used to evaluate the experimental results and it fits well. KEY WORDS: Functionalized Membrane, Dechlorination, Responsive, Tunable, Full-scale.

  2. Natural selection on thermal preference, critical thermal maxima and locomotor performance.

    Science.gov (United States)

    Gilbert, Anthony L; Miles, Donald B

    2017-08-16

    Climate change is resulting in a radical transformation of the thermal quality of habitats across the globe. Whereas species have altered their distributions to cope with changing environments, the evidence for adaptation in response to rising temperatures is limited. However, to determine the potential of adaptation in response to thermal variation, we need estimates of the magnitude and direction of natural selection on traits that are assumed to increase persistence in warmer environments. Most inferences regarding physiological adaptation are based on interspecific analyses, and those of selection on thermal traits are scarce. Here, we estimate natural selection on major thermal traits used to assess the vulnerability of ectothermic organisms to altered thermal niches. We detected significant directional selection favouring lizards with higher thermal preferences and faster sprint performance at their optimal temperature. Our analyses also revealed correlational selection between thermal preference and critical thermal maxima, where individuals that preferred warmer body temperatures with cooler critical thermal maxima were favoured by selection. Recent published estimates of heritability for thermal traits suggest that, in concert with the strong selective pressures we demonstrate here, evolutionary adaptation may promote long-term persistence of ectotherms in altered thermal environments. © 2017 The Author(s).

  3. Plant mortality and natural selection may increase biomass yield in switchgrass swards

    Science.gov (United States)

    Switchgrass (Panicum virgatum L.) is an important candidate for bioenergy feedstock production, prompting significant efforts to increase the number of breeding programs and the output of those programs. The objective of this experiment was to determine the potential utility of natural selection for...

  4. Human vs. Computer Diagnosis of Students' Natural Selection Knowledge: Testing the Efficacy of Text Analytic Software

    Science.gov (United States)

    Nehm, Ross H.; Haertig, Hendrik

    2012-01-01

    Our study examines the efficacy of Computer Assisted Scoring (CAS) of open-response text relative to expert human scoring within the complex domain of evolutionary biology. Specifically, we explored whether CAS can diagnose the explanatory elements (or Key Concepts) that comprise undergraduate students' explanatory models of natural selection with…

  5. Darwin's Arguments in Favour of Natural Selection and against Special Creationism

    Science.gov (United States)

    Nola, Robert

    2013-01-01

    In many places in "The Origin of Species", Darwin compares his own theory of Natural Selection favourably with Special Creationism which comes off as a bad second best. He does this using some version of the argument form known as "Inference to the Best Explanation". The first part of this paper is methodological. It considers Whewell's notion of…

  6. Using the FAR Guide to Teach Simulations: An Example with Natural Selection

    Science.gov (United States)

    Sickel, Aaron J.; Friedrichsen, Patricia J.

    2012-01-01

    Engaging students in a predator-prey simulation to teach natural selection is a common activity in secondary biology classrooms. The purpose of this article is to demonstrate how the authors have changed their approach to teaching this activity from a laboratory investigation to a class-constructed simulation. Specifically, the authors drew upon a…

  7. Influences of Teleological and Lamarckian Thinking on Student Understanding of Natural Selection

    Science.gov (United States)

    Stover, Shawn K.; Mabry, Michelle L.

    2007-01-01

    Previous research has demonstrated creationist, Lamarckian, and teleological reasoning in high school and college students. These lines of thinking conflict with the Darwinian notion of natural selection, which serves as the primary catalyst for biological evolution. The current study assessed evolutionary conceptions in non-science majors,…

  8. On the Origin of Species by Means of Natural Selection, or the ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 2. On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. Charles Darwin. Classics Volume 14 Issue 2 February 2009 pp 204-208 ...

  9. The Power of Natural Selection: A Guided Investigation of Three Case Studies

    Science.gov (United States)

    Beachly, William

    2010-01-01

    I describe a quantitative approach to three case studies in evolution that can be used to challenge college freshmen to explore the power of natural selection and ask questions that foster a deeper understanding of its operation and relevance. Hemochromatosis, the peppered moth, and hominid cranial capacity are investigated with a common algebraic…

  10. Reasoning about Natural Selection: Diagnosing Contextual Competency Using the ACORNS Instrument

    Science.gov (United States)

    Nehm, Ross H.; Beggrow, Elizabeth P.; Opfer, John E.; Ha, Minsu

    2012-01-01

    Studies of students' thinking about natural selection have revealed that the scenarios in which students reason evoke different types, magnitudes, and arrangements of knowledge elements and misconceptions. Diagnostic tests are needed that probe students' thinking across a representative array of evolutionary contexts. The ACORNS is a diagnostic…

  11. High School Biology Students' Transfer of the Concept of Natural Selection: A Mixed-Methods Approach

    Science.gov (United States)

    Pugh, Kevin J.; Koskey, Kristin L. K.; Linnenbrink-Garcia, Lisa

    2014-01-01

    The concept of natural selection serves as a foundation for understanding diverse biological concepts and has broad applicability to other domains. However, we know little about students' abilities to transfer (i.e. apply to a new context or use generatively) this concept and the relation between students' conceptual understanding and transfer…

  12. Unweaving Misconceptions: Guided Learning, Simulations, and Misconceptions in Learning Principles of Natural Selection

    Science.gov (United States)

    Weeks, Brian E.

    2013-01-01

    College students often come to the study of evolutionary biology with many misconceptions of how the processes of natural selection and speciation occur. How to relinquish these misconceptions with learners is a question that many educators face in introductory biology courses. Constructivism as a theoretical framework has become an accepted and…

  13. The Future of Natural Selection Knowledge Measurement: A Reply to Anderson et al. (2010)

    Science.gov (United States)

    Nehm, Ross H.; Schonfeld, Irvin Sam

    2010-01-01

    The development of rich, reliable, and robust measures of the composition, structure, and stability of student thinking about core scientific ideas (such as natural selection) remains a complex challenge facing science educators. In their recent article (Nehm & Schonfeld 2008), the authors explored the strengths, weaknesses, and insights provided…

  14. Changing Minds with the Story of Adaptation: Strategies for Teaching Young Children about Natural Selection

    Science.gov (United States)

    Emmons, Natalie; Smith, Hayley; Kelemen, Deborah

    2016-01-01

    Research Findings: Educational guidelines recommend a delayed, piecemeal approach to instruction on adaptation by natural selection. This approach is questionable given suggestions that older students' pervasive misunderstandings about adaptation are rooted in cognitive biases that develop early. In response to this, Kelemen et al. (2014) recently…

  15. Notice of release for Eagle Germplasm western yarrow (selected germplasm, natural track)

    Science.gov (United States)

    Scott M. Lambert; Stephen B. Monsen; Nancy Shaw

    2011-01-01

    The United States Department of Agriculture, Forest Service, Rocky Mountain Research Station; United States Department of the Interior, Bureau of Land Management, Idaho State Office; Utah State University, Agricultural Experiment Station; and University of Idaho, Agricultural Experiment Station, announce the release of a selected germplasm (natural track) of western...

  16. "Tell Me a Story": The Use of Narrative as a Learning Tool for Natural Selection

    Science.gov (United States)

    Prins, Renate; Avraamidou, Lucy; Goedhart, Martin

    2017-01-01

    Grounded within literature pointing to the value of narrative in communicating scientific information, the purpose of this study was to examine the use of stories as a tool for teaching about natural selection in the context of school science. The study utilizes a mixed method, case study approach which focuses on the design, implementation, and…

  17. Weldon's Search for a Direct Proof of Natural Selection and the ...

    Indian Academy of Sciences (India)

    fused, reception to Darwin's principle of natural selection in the .... This was the context in which he developed a particulate theory of heredity – 'pangenesis'. He ... Thereafter, following the independent rediscovery of Mendelian laws by de Vries, .... differences in traits among individuals that could be transmitted to offspring.

  18. Natural Selection in Cancer Biology: From Molecular Snowflakes to Trait Hallmarks

    Science.gov (United States)

    Fortunato, Angelo; Boddy, Amy; Mallo, Diego; Aktipis, Athena; Maley, Carlo C.; Pepper, John W.

    2017-01-01

    Evolution by natural selection is the conceptual foundation for nearly every branch of biology and increasingly also for biomedicine and medical research. In cancer biology, evolution explains how populations of cells in tumors change over time. It is a fundamental question whether this evolutionary process is driven primarily by natural selection and adaptation or by other evolutionary processes such as founder effects and drift. In cancer biology, as in organismal evolutionary biology, there is controversy about this question and also about the use of adaptation through natural selection as a guiding framework for research. In this review, we discuss the differences and similarities between evolution among somatic cells versus evolution among organisms. We review what is known about the parameters and rate of evolution in neoplasms, as well as evidence for adaptation. We conclude that adaptation is a useful framework that accurately explains the defining characteristics of cancer. Further, convergent evolution through natural selection provides the only satisfying explanation both for how a group of diverse pathologies have enough in common to usefully share the descriptive label of “cancer” and for why this convergent condition becomes life-threatening. PMID:28148564

  19. Evolving Better Cars: Teaching Evolution by Natural Selection with a Digital Inquiry Activity

    Science.gov (United States)

    Royer, Anne M.; Schultheis, Elizabeth H.

    2014-01-01

    Evolutionary experiments are usually difficult to perform in the classroom because of the large sizes and long timescales of experiments testing evolutionary hypotheses. Computer applications give students a window to observe evolution in action, allowing them to gain comfort with the process of natural selection and facilitating inquiry…

  20. Neutral Theory: From Complex Population History to Natural Selection and Sociocultural Phenomena in Human Populations.

    Science.gov (United States)

    Austerlitz, Frédéric; Heyer, Evelyne

    2018-06-01

    Here, we present a synthetic view on how Kimura's Neutral theory has helped us gaining insight on the different evolutionary forces that shape human evolution. We put this perspective in the frame of recent emerging challenges: the use of whole genome data for reconstructing population histories, natural selection on complex polygenic traits, and integrating cultural processes in human evolution.

  1. Natural Selection in Cancer Biology: From Molecular Snowflakes to Trait Hallmarks.

    Science.gov (United States)

    Fortunato, Angelo; Boddy, Amy; Mallo, Diego; Aktipis, Athena; Maley, Carlo C; Pepper, John W

    2017-02-01

    Evolution by natural selection is the conceptual foundation for nearly every branch of biology and increasingly also for biomedicine and medical research. In cancer biology, evolution explains how populations of cells in tumors change over time. It is a fundamental question whether this evolutionary process is driven primarily by natural selection and adaptation or by other evolutionary processes such as founder effects and drift. In cancer biology, as in organismal evolutionary biology, there is controversy about this question and also about the use of adaptation through natural selection as a guiding framework for research. In this review, we discuss the differences and similarities between evolution among somatic cells versus evolution among organisms. We review what is known about the parameters and rate of evolution in neoplasms, as well as evidence for adaptation. We conclude that adaptation is a useful framework that accurately explains the defining characteristics of cancer. Further, convergent evolution through natural selection provides the only satisfying explanation both for how a group of diverse pathologies have enough in common to usefully share the descriptive label of "cancer" and for why this convergent condition becomes life-threatening. Copyright © 2017 Cold Spring Harbor Laboratory Press; all rights reserved.

  2. The Creativity of Natural Selection? Part I: Darwin, Darwinism, and the Mutationists.

    Science.gov (United States)

    Beatty, John

    2016-12-01

    This is the first of a two-part essay on the history of debates concerning the creativity of natural selection, from Darwin through the evolutionary synthesis and up to the present. Here I focus on the mid-late nineteenth century to the early twentieth, with special emphasis on early Darwinism and its critics, the self-styled "mutationists." The second part focuses on the evolutionary synthesis and some of its critics, especially the "neutralists" and "neo-mutationists." Like Stephen Gould, I consider the creativity of natural selection to be a key component of what has traditionally counted as "Darwinism." I argue that the creativity of natural selection is best understood in terms of (1) selection initiating evolutionary change, and (2) selection being responsible for the presence of the variation it acts upon, for example by directing the course of variation. I consider the respects in which both of these claims sound non-Darwinian, even though they have long been understood by supporters and critics alike to be virtually constitutive of Darwinism.

  3. Intraspecific shape variation in horseshoe crabs: the importance of sexual and natural selection for local adaptation

    DEFF Research Database (Denmark)

    Faurby, Søren; Nielsen, Kasper Sauer Kollerup; Bussarawit, Somchai

    2011-01-01

    . Differences in shape variation between sexes were tested with F-tests, which showed lower intrapopulation morphometric variation in males than females. These results indicate a lower degree of local adaptation on body shape in C. rotundicauda and T. gigas than in L. polyphemus and a lower degree of local......A morphometric analysis of the body shape of three species of horseshoe crabs was undertaken in order to infer the importance of natural and sexual selection. It was expected that natural selection would be most intense, leading to highest regional differentiation, in the American species Limulus...... polyphemus, which has the largest climatic differences between different populations. Local adaptation driven by sexual selection was expected in males but not females because horseshoe crab mating behaviour leads to competition between males, but not between females. Three hundred fifty-nine horseshoe crabs...

  4. The natural selection of organizational and safety culture within a small to medium sized enterprise (SME).

    Science.gov (United States)

    Brooks, Benjamin

    2008-01-01

    Small to Medium Sized Enterprises (SMEs) form the majority of Australian businesses. This study uses ethnographic research methods to describe the organizational culture of a small furniture-manufacturing business in southern Australia. Results show a range of cultural assumptions variously 'embedded' within the enterprise. In line with memetics - Richard Dawkin's cultural application of Charles Darwin's theory of Evolution by Natural Selection, the author suggests that these assumptions compete to be replicated and retained within the organization. The author suggests that dominant assumptions are naturally selected, and that the selection can be better understood by considering the cultural assumptions in reference to Darwin's original principles and Frederik Barth's anthropological framework of knowledge. The results are discussed with reference to safety systems, negative cultural elements called Cultural Safety Viruses, and how our understanding of this particular organizational culture might be used to build resistance to these viruses.

  5. Unweaving misconceptions: Guided learning, simulations, and misconceptions in learning principles of natural selection

    Science.gov (United States)

    Weeks, Brian E.

    College students often come to the study of evolutionary biology with many misconceptions of how the processes of natural selection and speciation occur. How to relinquish these misconceptions with learners is a question that many educators face in introductory biology courses. Constructivism as a theoretical framework has become an accepted and promoted model within the epistemology of science instruction. However, constructivism is not without its skeptics who see some problems of its application in lacking necessary guidance for novice learners. This study within a quantitative, quasi-experimental format tested whether guided online instruction in a video format of common misconceptions in evolutionary biology produced higher performance on a survey of knowledge of natural selection versus more constructivist style learning in the form of student exploration of computer simulations of the evolutionary process. Performances on surveys were also explored for a combination of constructivist and guided techniques to determine if a consolidation of approaches produced higher test scores. Out of the 94 participants 95% displayed at least one misconception of natural selection in the pre-test while the study treatments produced no statistically significant improvements in post-test scores except within the video (guided learning treatment). These overall results demonstrated the stubbornness of misconceptions involving natural selection for adult learners and the difficulty of helping them overcome them. It also bolsters the idea that some misconceptions of natural selection and evolution may be hardwired in a neurological sense and that new, more long-term teaching techniques may be warranted. Such long-term strategies may not be best implemented with constructivist techniques alone, and it is likely that some level of guidance may be necessary for novice adult learners. A more substantial, nuanced approach for undergraduates is needed that consolidates successful

  6. On the interpretation and relevance of the Fundamental Theorem of Natural Selection.

    Science.gov (United States)

    Ewens, Warren J; Lessard, Sabin

    2015-09-01

    The attempt to understand the statement, and then to find the interpretation, of Fisher's "Fundamental Theorem of Natural Selection" caused problems for generations of population geneticists. Price's (1972) paper was the first to lead to an understanding of the statement of the theorem. The theorem shows (in the discrete-time case) that the so-called "partial change" in mean fitness of a population between a parental generation and an offspring generation is the parental generation additive genetic variance in fitness divided by the parental generation mean fitness. In the continuous-time case the partial rate of change in mean fitness is equal to the parental generation additive genetic variance in fitness with no division by the mean fitness. This "partial change" has been interpreted by some as the change in mean fitness due to changes in gene frequency, and by others as the change in mean fitness due to natural selection. (Fisher variously used both interpretations.) In this paper we discuss these interpretations of the theorem. We indicate why we are unhappy with both. We also discuss the long-term relevance of the Fundamental Theorem of Natural Selection, again reaching a negative assessment. We introduce and discuss the concept of genic evolutionary potential. We finally review an optimizing theorem that involves changes in gene frequency, the additive genetic variance in fitness and the mean fitness itself, all of which are involved in the Fundamental Theorem of Natural Selection, and which is free of the difficulties in interpretation of the Fundamental Theorem of Natural Selection. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Genetic polymorphism and natural selection of Duffy binding protein of Plasmodium vivax Myanmar isolates

    Science.gov (United States)

    2012-01-01

    Background Plasmodium vivax Duffy binding protein (PvDBP) plays an essential role in erythrocyte invasion and a potential asexual blood stage vaccine candidate antigen against P. vivax. The polymorphic nature of PvDBP, particularly amino terminal cysteine-rich region (PvDBPII), represents a major impediment to the successful design of a protective vaccine against vivax malaria. In this study, the genetic polymorphism and natural selection at PvDBPII among Myanmar P. vivax isolates were analysed. Methods Fifty-four P. vivax infected blood samples collected from patients in Myanmar were used. The region flanking PvDBPII was amplified by PCR, cloned into Escherichia coli, and sequenced. The polymorphic characters and natural selection of the region were analysed using the DnaSP and MEGA4 programs. Results Thirty-two point mutations (28 non-synonymous and four synonymous mutations) were identified in PvDBPII among the Myanmar P. vivax isolates. Sequence analyses revealed that 12 different PvDBPII haplotypes were identified in Myanmar P. vivax isolates and that the region has evolved under positive natural selection. High selective pressure preferentially acted on regions identified as B- and T-cell epitopes of PvDBPII. Recombination may also be played a role in the resulting genetic diversity of PvDBPII. Conclusions PvDBPII of Myanmar P. vivax isolates displays a high level of genetic polymorphism and is under selective pressure. Myanmar P. vivax isolates share distinct types of PvDBPII alleles that are different from those of other geographical areas. These results will be useful for understanding the nature of the P. vivax population in Myanmar and for development of PvDBPII-based vaccine. PMID:22380592

  8. Seasonal movements and multiscale habitat selection of Whooping Crane (Grus americana) in natural and agricultural wetlands

    Science.gov (United States)

    Pickens, Bradley A.; King, Sammy L.; Vasseur, Phillip L.; Zimorski, Sara E.; Selman, Will

    2017-01-01

    Eleven of 15 species of cranes (family: Gruidae) are considered vulnerable or endangered, and the increase of agriculture and aquaculture at the expense of natural wetlands and grasslands is a threat to Gruidae worldwide. A reintroduced population of Whooping Crane (Grus americana) was studied in coastal and agricultural wetlands of Louisiana and Texas, USA. The objectives were to compare Whooping Crane movements across seasons, quantify multiscale habitat selection, and identify seasonal shifts in selection. Whooping Cranes (n = 53) were tracked with satellite transmitters to estimate seasonal core-use areas (50% home range contours) via Brownian bridge movement models and assess habitat selection. Whooping Crane core-use areas (n = 283) ranged from 4.7 to 438.0 km2, and habitat selection changed seasonally as shallow water availability varied. Whooping Crane core-use areas were composed of more fresh marsh in spring/summer, but shifted towards rice and crawfish (Procambarus spp.) aquaculture in the fall/winter. Within core-use areas, aquaculture was most strongly selected, particularly in fall when fresh marsh became unsuitable. Overall, the shifting of Whooping Crane habitat selection over seasons is likely to require large, heterogeneous areas. Whooping Crane use of agricultural and natural wetlands may depend on spatio-temporal dynamics of water depth.

  9. Evidence for natural selection at the melanocortin-3 receptor gene in European and African populations.

    Science.gov (United States)

    Yoshiuchi, Issei

    2016-08-01

    Obesity is increasing steadily in worldwide prevalence and is known to cause serious health problems in association with type 2 diabetes mellitus (T2DM), including hypertension, stroke, and cardiovascular diseases. According to the thrifty gene hypothesis, the natural selection of obesity-related genes is important during feast and famine because they control body weight and fat levels. Past human adaptations to environmental changes in food supply, lifestyle, and geography may have influenced the selection of genes associated with the metabolism of glucose, lipids, and energy. The melanocortin-3 receptor gene (MC3R) is associated with obesity, with MC3R-deficient mice showing increased fat mass. MC3R variations are also linked with childhood obesity and insulin resistance. Here, we aimed to uncover evidence of selection at MC3R. We performed a three-step method to detect selection at MC3R using HapMap population data. We used Wright's F statistics as a measure of population differentiation, the long-range haplotype test to identify extended haplotypes, and the integrated haplotype score (iHS) to detect selection at MC3R. We observed high population differentiation between European and African populations at two MC3R childhood obesity- and insulin resistance-associated single-nucleotide polymorphisms (rs3746619 and rs3827103) using Wright's F statistics. The iHS revealed evidence of natural selection at MC3R. These findings provide evidence for natural selection at MC3R. Further investigation is warranted into adaptive evolution at T2DM- and obesity-associated genes.

  10. Selection of the wavelet function for the frequencies estimation

    International Nuclear Information System (INIS)

    Garcia R, A.

    2007-01-01

    At the moment the signals are used to diagnose the state of the systems, by means of the extraction of their more important characteristics such as the frequencies, tendencies, changes and temporary evolutions. This characteristics are detected by means of diverse analysis techniques, as Autoregressive methods, Fourier Transformation, Fourier transformation in short time, Wavelet transformation, among others. The present work uses the one Wavelet transformation because it allows to analyze stationary, quasi-stationary and transitory signals in the time-frequency plane. It also describes a methodology to select the scales and the Wavelet function to be applied the one Wavelet transformation with the objective of detecting to the dominant system frequencies. (Author)

  11. Preparatory selection of sterilization regime for canned Natural Atlantic Mackerel with oil based on developed mathematical models of the process

    Directory of Open Access Journals (Sweden)

    Maslov A. A.

    2016-12-01

    Full Text Available Definition of preparatory parameters for sterilization regime of canned "Natural Atlantic Mackerel with Oil" is the aim of current study. PRSC software developed at the department of automation and computer engineering is used for preparatory selection. To determine the parameters of process model, in laboratory autoclave AVK-30M the pre-trial process of sterilization and cooling in water with backpressure of canned "Natural Atlantic Mackerel with Oil" in can N 3 has been performed. Gathering information about the temperature in the autoclave sterilization chamber and the can with product has been carried out using Ellab TrackSense PRO loggers. Due to the obtained information three transfer functions for the product model have been identified: in the least heated area of autoclave, the average heated and the most heated. In PRSC programme temporary temperature dependences in the sterilization chamber have been built using this information. The model of sterilization process of canned "Natural Atlantic Mackerel with Oil" has been received after the pre-trial process. Then in the automatic mode the sterilization regime of canned "Natural Atlantic Mackerel with Oil" has been selected using the value of actual effect close to normative sterilizing effect (5.9 conditional minutes. Furthermore, in this study step-mode sterilization of canned "Natural Atlantic Mackerel with Oil" has been selected. Utilization of step-mode sterilization with the maximum temperature equal to 125 °C in the sterilization chamber allows reduce process duration by 10 %. However, the application of this regime in practice requires additional research. Using the described approach based on the developed mathematical models of the process allows receive optimal step and variable canned food sterilization regimes with high energy efficiency and product quality.

  12. Pollen limitation and its influence on natural selection through seed set.

    Science.gov (United States)

    Bartkowska, M P; Johnston, M O

    2015-11-01

    Stronger pollen limitation should increase competition among plants, leading to stronger selection on traits important for pollen receipt. The few explicit tests of this hypothesis, however, have provided conflicting support. Using the arithmetic relationship between these two quantities, we show that increased pollen limitation will automatically result in stronger selection (all else equal) although other factors can alter selection independently of pollen limitation. We then tested the hypothesis using two approaches. First, we analysed the published studies containing information on both pollen limitation and selection. Second, we explored how natural selection measured in one Ontario population of Lobelia cardinalis over 3 years and two Michigan populations in 1 year relates to pollen limitation. For the Ontario population, we also explored whether pollinator-mediated selection is related to pollen limitation. Consistent with the hypothesis, we found an overall positive relationship between selection strength and pollen limitation both among species and within L. cardinalis. Unexpectedly, this relationship was found even for vegetative traits among species, and was not found in L. cardinalis for pollinator-mediated selection on nearly all trait types. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

  13. Reliable Path Selection Problem in Uncertain Traffic Network after Natural Disaster

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2013-01-01

    Full Text Available After natural disaster, especially for large-scale disasters and affected areas, vast relief materials are often needed. In the meantime, the traffic networks are always of uncertainty because of the disaster. In this paper, we assume that the edges in the network are either connected or blocked, and the connection probability of each edge is known. In order to ensure the arrival of these supplies at the affected areas, it is important to select a reliable path. A reliable path selection model is formulated, and two algorithms for solving this model are presented. Then, adjustable reliable path selection model is proposed when the edge of the selected reliable path is broken. And the corresponding algorithms are shown to be efficient both theoretically and numerically.

  14. Natural selection on protein-coding genes in the human genome

    DEFF Research Database (Denmark)

    Bustamente, Carlos D.; Fledel-Alon, Adi; Williamson, Scott

    2005-01-01

    , showing an excess of deleterious variation within local populations 9, 10 . Here we contrast patterns of coding sequence polymorphism identified by direct sequencing of 39 humans for over 11,000 genes to divergence between humans and chimpanzees, and find strong evidence that natural selection has shaped......Comparisons of DNA polymorphism within species to divergence between species enables the discovery of molecular adaptation in evolutionarily constrained genes as well as the differentiation of weak from strong purifying selection 1, 2, 3, 4 . The extent to which weak negative and positive darwinian...... selection have driven the molecular evolution of different species varies greatly 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 , with some species, such as Drosophila melanogaster, showing strong evidence of pervasive positive selection 6, 7, 8, 9 , and others, such as the selfing weed Arabidopsis thaliana...

  15. On theoretical models of gene expression evolution with random genetic drift and natural selection.

    Directory of Open Access Journals (Sweden)

    Osamu Ogasawara

    2009-11-01

    Full Text Available The relative contributions of natural selection and random genetic drift are a major source of debate in the study of gene expression evolution, which is hypothesized to serve as a bridge from molecular to phenotypic evolution. It has been suggested that the conflict between views is caused by the lack of a definite model of the neutral hypothesis, which can describe the long-run behavior of evolutionary change in mRNA abundance. Therefore previous studies have used inadequate analogies with the neutral prediction of other phenomena, such as amino acid or nucleotide sequence evolution, as the null hypothesis of their statistical inference.In this study, we introduced two novel theoretical models, one based on neutral drift and the other assuming natural selection, by focusing on a common property of the distribution of mRNA abundance among a variety of eukaryotic cells, which reflects the result of long-term evolution. Our results demonstrated that (1 our models can reproduce two independently found phenomena simultaneously: the time development of gene expression divergence and Zipf's law of the transcriptome; (2 cytological constraints can be explicitly formulated to describe long-term evolution; (3 the model assuming that natural selection optimized relative mRNA abundance was more consistent with previously published observations than the model of optimized absolute mRNA abundances.The models introduced in this study give a formulation of evolutionary change in the mRNA abundance of each gene as a stochastic process, on the basis of previously published observations. This model provides a foundation for interpreting observed data in studies of gene expression evolution, including identifying an adequate time scale for discriminating the effect of natural selection from that of random genetic drift of selectively neutral variations.

  16. Contemporary evolution during invasion: evidence for differentiation, natural selection, and local adaptation.

    Science.gov (United States)

    Colautti, Robert I; Lau, Jennifer A

    2015-05-01

    Biological invasions are 'natural' experiments that can improve our understanding of contemporary evolution. We evaluate evidence for population differentiation, natural selection and adaptive evolution of invading plants and animals at two nested spatial scales: (i) among introduced populations (ii) between native and introduced genotypes. Evolution during invasion is frequently inferred, but rarely confirmed as adaptive. In common garden studies, quantitative trait differentiation is only marginally lower (~3.5%) among introduced relative to native populations, despite genetic bottlenecks and shorter timescales (i.e. millennia vs. decades). However, differentiation between genotypes from the native vs. introduced range is less clear and confounded by nonrandom geographic sampling; simulations suggest this causes a high false-positive discovery rate (>50%) in geographically structured populations. Selection differentials (¦s¦) are stronger in introduced than in native species, although selection gradients (¦β¦) are not, consistent with introduced species experiencing weaker genetic constraints. This could facilitate rapid adaptation, but evidence is limited. For example, rapid phenotypic evolution often manifests as geographical clines, but simulations demonstrate that nonadaptive trait clines can evolve frequently during colonization (~two-thirds of simulations). Additionally, QST-FST studies may often misrepresent the strength and form of natural selection acting during invasion. Instead, classic approaches in evolutionary ecology (e.g. selection analysis, reciprocal transplant, artificial selection) are necessary to determine the frequency of adaptive evolution during invasion and its influence on establishment, spread and impact of invasive species. These studies are rare but crucial for managing biological invasions in the context of global change. © 2015 John Wiley & Sons Ltd.

  17. Clonal selection of vitis vinifera cv. malbec: Confluence of science and nature

    Directory of Open Access Journals (Sweden)

    Aldo Biondolillo

    2014-01-01

    Full Text Available It is not overstated that Argentinean viticulture identifies with Malbec, the vine which long ago was introduced in the country from France and which has marvelously naturalized here. However, the variety Malbec has many different expressions, depending very much on environmental and cultivating conditions and on natural mutations occurred over time. A modern viticulture cannot do without the capability of exactly identifying and differentiating clones of the same variety and from the ability to do that over contingency. This work on clonal selection, conceived and developed by a very polyvalent team, focuses exactly on defining instruments to unequivocally distinguish and select different clones and using these instruments to analyze, classify and select all different clones representing the highest variability of Malbec in Argentina ever sampled. The work bases on traditional instruments – phenotypic and enological analysis – and on a molecular marker selection program. Through the synergy of all these methods the team has come to the selection of 16 superior clones of Malbec and will proceed by sharing and mapping three of those clones on the country different micro-environments for grapevine growing regions, giving Argentinean viticulture a key instrument to identify its most valuable grape wine variety.

  18. Natural Gamma Emitters after a Selective Chemical Separation of a TENORM residue: Preliminary Results

    International Nuclear Information System (INIS)

    Alves de Freitas, Antonio; Abrao, Alcidio; Godoy dos Santos, Adir Janete; Pecequilo, Brigitte Roxana Soreanu

    2008-01-01

    An analytical procedure was established in order to obtain selective fractions containing radium isotopes ( 228 Ra), thorium ( 232 Th), and rare earths from RETOTER (REsiduo de TOrio e TErras Raras), a solid residue rich in rare earth elements, thorium isotopes and small amount of natural uranium generated from the operation of a thorium pilot plant for purification and production of pure thorium nitrate at IPEN -CNEN/SP. The paper presents preliminary results of 228 Ra, 226 Ra, 238 U, 210 Pb, and 40 K concentrations in the selective fractions and total residue determined by high-resolution gamma spectroscopy, considering radioactive equilibrium of the samples

  19. COMPARATIVE ANALYSIS OF BEHAVIOURS RELATED TO FUNCTIONAL FOODS AMONG SELECTED YOUNG CONSUMERS IN POLAND AND GERMANY

    Directory of Open Access Journals (Sweden)

    Magdalena Zegan

    2016-12-01

    Full Text Available Nutrition is one of the key factors infl uencing human health. Consuming foods that either naturally contain or have been enriched with bioactive substances may aid the organism’s proper development and functioning and, most importantly, be a vital element in the prophylaxis of many non-communicable diseases as well as improve general sense of well-being. The aim of the study was to compare behaviours related to functional foods among a selected group of young people. The survey was conducted among 153 purposively selected young consumers from Poland and Germany in March/April 2015. An original survey questionnaire was employed. IBM SPSS Statistics ver. 23 software was used for statistical analysis (chi-squared test p < 0.05. The term “functional foods” was largely unknown among the respondents. A defi nite majority of the survey participants reported having bought and consumed products that, in fact, belong to this group of foods. The main source of information on the topic of functional foods was the Internet. While buying these products, respondents from both countries chiefl y took into account the price, the quality and the list of ingredients. The results point to the need to popularize information about functional foods using trustworthy sources, in order to foster nutritional awareness. Consumer knowledge is the basis for the positive perception and acceptance of health-promoting foods and for making rational dietary choices. 

  20. Molecular descriptor subset selection in theoretical peptide quantitative structure-retention relationship model development using nature-inspired optimization algorithms.

    Science.gov (United States)

    Žuvela, Petar; Liu, J Jay; Macur, Katarzyna; Bączek, Tomasz

    2015-10-06

    In this work, performance of five nature-inspired optimization algorithms, genetic algorithm (GA), particle swarm optimization (PSO), artificial bee colony (ABC), firefly algorithm (FA), and flower pollination algorithm (FPA), was compared in molecular descriptor selection for development of quantitative structure-retention relationship (QSRR) models for 83 peptides that originate from eight model proteins. The matrix with 423 descriptors was used as input, and QSRR models based on selected descriptors were built using partial least squares (PLS), whereas root mean square error of prediction (RMSEP) was used as a fitness function for their selection. Three performance criteria, prediction accuracy, computational cost, and the number of selected descriptors, were used to evaluate the developed QSRR models. The results show that all five variable selection methods outperform interval PLS (iPLS), sparse PLS (sPLS), and the full PLS model, whereas GA is superior because of its lowest computational cost and higher accuracy (RMSEP of 5.534%) with a smaller number of variables (nine descriptors). The GA-QSRR model was validated initially through Y-randomization. In addition, it was successfully validated with an external testing set out of 102 peptides originating from Bacillus subtilis proteomes (RMSEP of 22.030%). Its applicability domain was defined, from which it was evident that the developed GA-QSRR exhibited strong robustness. All the sources of the model's error were identified, thus allowing for further application of the developed methodology in proteomics.

  1. A surface acoustic wave sensor functionalized with a polypyrrole molecularly imprinted polymer for selective dopamine detection.

    Science.gov (United States)

    Maouche, Naima; Ktari, Nadia; Bakas, Idriss; Fourati, Najla; Zerrouki, Chouki; Seydou, Mahamadou; Maurel, François; Chehimi, Mohammed Mehdi

    2015-11-01

    A surface acoustic wave sensor operating at 104 MHz and functionalized with a polypyrrole molecularly imprinted polymer has been designed for selective detection of dopamine (DA). Optimization of pyrrole/DA ratio, polymerization and immersion times permitted to obtain a highly selective sensor, which has a sensitivity of 0.55°/mM (≈ 550 Hz/mM) and a detection limit of ≈ 10 nM. Morphology and related roughness parameters of molecularly imprinted polymer surfaces, before and after extraction of DA, as well as that of the non imprinted polymer were characterized by atomic force microscopy. The developed chemosensor selectively recognized dopamine over the structurally similar compound 4-hydroxyphenethylamine (referred as tyramine), or ascorbic acid,which co-exists with DA in body fluids at a much higher concentration. Selectivity tests were also carried out with dihydroxybenzene, for which an unexpected phase variation of order of 75% of the DA one was observed. Quantum chemical calculations, based on the density functional theory, were carried out to determine the nature of interactions between each analyte and the PPy matrix and the DA imprinted PPy polypyrrole sensing layer in order to account for the important phase variation observed during dihydroxybenzene injection. Copyright © 2015 John Wiley & Sons, Ltd.

  2. Gis-Based Site Selection for Underground Natural Resources Using Fuzzy Ahp-Owa

    Science.gov (United States)

    Sabzevari, A. R.; Delavar, M. R.

    2017-09-01

    Fuel consumption has significantly increased due to the growth of the population. A solution to address this problem is the underground storage of natural gas. The first step to reach this goal is to select suitable places for the storage. In this study, site selection for the underground natural gas reservoirs has been performed using a multi-criteria decision-making in a GIS environment. The "Ordered Weighted Average" (OWA) operator is one of the multi-criteria decision-making methods for ranking the criteria and consideration of uncertainty in the interaction among the criteria. In this paper, Fuzzy AHP_OWA (FAHP_OWA) is used to determine optimal sites for the underground natural gas reservoirs. Fuzzy AHP_OWA considers the decision maker's risk taking and risk aversion during the decision-making process. Gas consumption rate, temperature, distance from main transportation network, distance from gas production centers, population density and distance from gas distribution networks are the criteria used in this research. Results show that the northeast and west of Iran and the areas around Tehran (Tehran and Alborz Provinces) have a higher attraction for constructing a natural gas reservoir. The performance of the used method was also evaluated. This evaluation was performed using the location of the existing natural gas reservoirs in the country and the site selection maps for each of the quantifiers. It is verified that the method used in this study is capable of modeling different decision-making strategies used by the decision maker with about 88 percent of agreement between the modeling and test data.

  3. Natural selection and family X location interaction in the common (dry bean plant

    Directory of Open Access Journals (Sweden)

    Luís Henrique Pirola

    2002-01-01

    Full Text Available Natural selection takes place while advancing generations of segregant populations of self pollinating species by the population (bulk method. There is evidence that it maintains the individuals with greater grain yield. The question arises whether natural selection preserves the individuals which are more adapted only to the environment where the generation advance occurred, that is, if it contributes to increasing the genotype x environment interaction in the family assessment. This study was carried out to check this hypothesis in the common bean plant using families derived from a segregating population from a cross between the Carioca MG x ESAL 686 cultivars. The segregating populations increase in homozygosity was obtained by the population (bulk method until the F14 generation, in three distinct locations in Minas Gerais state: Lavras, Lambari and Patos de Minas. Forty-seven F14:15 families were randomly taken from the population in each location and later multiplied to obtain F14:16 families. These families were jointly assessed with three controls using a triple 12 x 12 lattice design in the three locations of generation advance in the wet season of 1998/1999. All the estimated parameters showed that while advancing segregant populations by the population (bulk method, natural selection acted to preserve the individuals which are more adapted to the environment in which they were advanced.

  4. Statistical aspects of evolution under natural selection, with implications for the advantage of sexual reproduction.

    Science.gov (United States)

    Crouch, Daniel J M

    2017-10-27

    The prevalence of sexual reproduction remains mysterious, as it poses clear evolutionary drawbacks compared to reproducing asexually. Several possible explanations exist, with one of the most likely being that finite population size causes linkage disequilibria to randomly generate and impede the progress of natural selection, and that these are eroded by recombination via sexual reproduction. Previous investigations have either analysed this phenomenon in detail for small numbers of loci, or performed population simulations for many loci. Here we present a quantitative genetic model for fitness, based on the Price Equation, in order to examine the theoretical consequences of randomly generated linkage disequilibria when there are many loci. In addition, most previous work has been concerned with the long-term consequences of deleterious linkage disequilibria for population fitness. The expected change in mean fitness between consecutive generations, a measure of short-term evolutionary success, is shown under random environmental influences to be related to the autocovariance in mean fitness between the generations, capturing the effects of stochastic forces such as genetic drift. Interaction between genetic drift and natural selection, due to randomly generated linkage disequilibria, is demonstrated to be one possible source of mean fitness autocovariance. This suggests a possible role for sexual reproduction in reducing the negative effects of genetic drift, thereby improving the short-term efficacy of natural selection. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Natural selection and sex differences in morbidity and mortality in early life.

    Science.gov (United States)

    Wells, J C

    2000-01-07

    Both morbidity and mortality are consistently reported to be higher in males than in females in early life, but no explanation for these findings has been offered. This paper argues that the sex difference in early vulnerability can be attributed to the natural selection of optimal maternal strategies for maximizing lifetime reproductive success, as modelled previously by Trivers and Willard. These authors theorized that males and females offer different returns on parental investment depending on the state of the environment. Natural selection has therefore favoured maternal ability to manipulate offspring sex in response to environmental conditions in early life, as shown in variation in the sex ratio at birth. This argument can be extended to the whole period of parental investment until weaning. Male vulnerability in response to environmental stress in early life is predicted to have been favoured by natural selection. This vulnerability is most evident in the harsh conditions resulting from pre-term birth, but can also be seen in term infants, and manifests as greater morbidity and mortality persisting into early childhood. Malnutrition, interacting with infection after birth, is suggested as the fundamental trigger mechanism. The model suggests that whatever improvements are made in medical care, any environmental stress will always affect males more severely than females in early life. Copyright 2000 Academic Press.

  6. Selective catalytic reduction (SCR) NOx control for small natural gas-fired prime movers

    International Nuclear Information System (INIS)

    Shareef, G.S.; Stone, D.K.; Ferry, K.R.; Johnson, K.L.; Locke, K.S.

    1992-01-01

    The application of selective catalytic reduction (SCR) to small natural gas-fired prime movers at cogeneration facilities and compressor stations could possibly increase due to regulatory forces to limit NO x from such sources. The natural gas industry is presently without a current database with which to evaluate the cost and operating characteristics of SCR under the conditions anticipated for small prime movers. This paper presents the results from a two-phase study undertaken to document SCR applications with emphasis on SCR system performance and costs. The database of small natural gas-fired prime mover SCR experience, focusing on prime mover characterization, SCR system performance, and SCR system costs will be described. Result from analysis of performance and cost data will be discussed, including analytical tools developed to project SCR system performance and costs

  7. First Report of the Select Committee on Energy: Securing natural gas for New Brunswick

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-11-01

    This document reports on the work of the Select Committee on Energy of the Legislative Assembly of New Brunswick, created to examine the proper and expeditious development of natural gas in New Brunswick, in such a way as to make natural gas available in the province to the widest possible extent, and to the maximum benefit of its people. The document outlines the key issues involved, namely the policy on laterals and pipeline access (a fundamental issue), cost of service and incentive regulation, bundled and unbundled services, load balancing, incentives for distribution system expansion, franchises, municipal involvement in gas development, the impact of natural gas industry development on restructuring the electric industry, environmental issues and required changes to legislation. Recommendations with respect to each issue are included.

  8. Selecting the Best Mobile Information Service with Natural Language User Input

    Science.gov (United States)

    Feng, Qiangze; Qi, Hongwei; Fukushima, Toshikazu

    Information services accessed via mobile phones provide information directly relevant to subscribers’ daily lives and are an area of dynamic market growth worldwide. Although many information services are currently offered by mobile operators, many of the existing solutions require a unique gateway for each service, and it is inconvenient for users to have to remember a large number of such gateways. Furthermore, the Short Message Service (SMS) is very popular in China and Chinese users would prefer to access these services in natural language via SMS. This chapter describes a Natural Language Based Service Selection System (NL3S) for use with a large number of mobile information services. The system can accept user queries in natural language and navigate it to the required service. Since it is difficult for existing methods to achieve high accuracy and high coverage and anticipate which other services a user might want to query, the NL3S is developed based on a Multi-service Ontology (MO) and Multi-service Query Language (MQL). The MO and MQL provide semantic and linguistic knowledge, respectively, to facilitate service selection for a user query and to provide adaptive service recommendations. Experiments show that the NL3S can achieve 75-95% accuracies and 85-95% satisfactions for processing various styles of natural language queries. A trial involving navigation of 30 different mobile services shows that the NL3S can provide a viable commercial solution for mobile operators.

  9. Selection, integration, and conflict monitoring; assessing the nature and generality of prefrontal cognitive control mechanisms.

    Science.gov (United States)

    Badre, David; Wagner, Anthony D

    2004-02-05

    Prefrontal cortex (PFC) supports flexible behavior by mediating cognitive control, though the elemental forms of control supported by PFC remain a central debate. Dorsolateral PFC (DLPFC) is thought to guide response selection under conditions of response conflict or, alternatively, may refresh recently active representations within working memory. Lateral frontopolar cortex (FPC) may also adjudicate response conflict, though others propose that FPC supports higher order control processes such as subgoaling and integration. Anterior cingulate cortex (ACC) is hypothesized to upregulate response selection by detecting response conflict; it remains unclear whether ACC functions generalize beyond monitoring response conflict. The present fMRI experiment directly tested these competing theories regarding the functional roles of DLPFC, FPC, and ACC. Results reveal dissociable control processes in PFC, with mid-DLPFC selectively mediating resolution of response conflict and FPC further mediating subgoaling/integration. ACC demonstrated a broad sensitivity to control demands, suggesting a generalized role in modulating cognitive control.

  10. Immunological characteristics and response to lipopolysaccharide of mouse lines selectively bred with natural and acquired immunities.

    Science.gov (United States)

    Narahara, Hiroki; Sakai, Eri; Katayama, Masafumi; Ohtomo, Yukiko; Yamamoto, Kanako; Takemoto, Miki; Aso, Hisashi; Ohwada, Shyuichi; Mohri, Yasuaki; Nishimori, Katsuhiko; Isogai, Emiko; Yamaguchi, Takahiro; Fukuda, Tomokazu

    2012-05-01

    Genetic improvement of resistance to infectious diseases is a challenging goal in animal breeding. Infection resistance involves multiple immunological characteristics, including natural and acquired immunity. In the present study, we developed an experimental model based on genetic selection, to improve immunological phenotypes. We selectively established three mouse lines based on phagocytic activity, antibody production and the combination of these two phenotypes. We analyzed the immunological characteristics of these lines using a lipopolysaccharide (LPS), which is one of the main components of Gram-negative bacteria. An intense immunological reaction was induced in each of the three mouse lines. Severe loss of body weight and liver damage were observed, and a high level of cytokine messenger RNA was detected in the liver tissue. The mouse line established using a combination of the two selection standards showed unique characteristics relative to the mouse lines selected on the basis of a single phenotype. Our results indicate that genetic selection and breeding is effective, even for immunological phenotypes with a relatively low heritability. Thus, it may be possible to improve resistance to infectious diseases by means of genetic selection. © 2011 The Authors. Animal Science Journal © 2011 Japanese Society of Animal Science.

  11. Hydroquinone and Quinone-Grafted Porous Carbons for Highly Selective CO2 Capture from Flue Gases and Natural Gas Upgrading.

    Science.gov (United States)

    Wang, Jun; Krishna, Rajamani; Yang, Jiangfeng; Deng, Shuguang

    2015-08-04

    Hydroquinone and quinone functional groups were grafted onto a hierarchical porous carbon framework via the Friedel-Crafts reaction to develop more efficient adsorbents for the selective capture and removal of carbon dioxide from flue gases and natural gas. The oxygen-doped porous carbons were characterized with scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. CO2, CH4, and N2 adsorption isotherms were measured and correlated with the Langmuir model. An ideal adsorbed solution theory (IAST) selectivity for the CO2/N2 separation of 26.5 (298 K, 1 atm) was obtained on the hydroquinone-grafted carbon, which is 58.7% higher than that of the pristine porous carbon, and a CO2/CH4 selectivity value of 4.6 (298 K, 1 atm) was obtained on the quinone-grafted carbon (OAC-2), which represents a 28.4% improvement over the pristine porous carbon. The highest CO2 adsorption capacity on the oxygen-doped carbon adsorbents is 3.46 mmol g(-1) at 298 K and 1 atm. In addition, transient breakthrough simulations for CO2/CH4/N2 mixture separation were conducted to demonstrate the good separation performance of the oxygen-doped carbons in fixed bed adsorbers. Combining excellent adsorption separation properties and low heats of adsorption, the oxygen-doped carbons developed in this work appear to be very promising for flue gas treatment and natural gas upgrading.

  12. Norwegian honey bees surviving Varroa destructor mite infestations by means of natural selection

    Directory of Open Access Journals (Sweden)

    Melissa A.Y. Oddie

    2017-10-01

    Full Text Available Background Managed, feral and wild populations of European honey bee subspecies, Apis mellifera, are currently facing severe colony losses globally. There is consensus that the ectoparasitic mite Varroa destructor, that switched hosts from the Eastern honey bee Apis cerana to the Western honey bee A. mellifera, is a key factor driving these losses. For >20 years, breeding efforts have not produced European honey bee colonies that can survive infestations without the need for mite control. However, at least three populations of European honey bees have developed this ability by means of natural selection and have been surviving for >10 years without mite treatments. Reduced mite reproductive success has been suggested as a key factor explaining this natural survival. Here, we report a managed A. mellifera population in Norway, that has been naturally surviving consistent V. destructor infestations for >17 years. Methods Surviving colonies and local susceptible controls were evaluated for mite infestation levels, mite reproductive success and two potential mechanisms explaining colony survival: grooming of adult worker bees and Varroa Sensitive Hygiene (VSH: adult workers specifically detecting and removing mite-infested brood. Results Mite infestation levels were significantly lower in surviving colonies and mite reproductive success was reduced by 30% when compared to the controls. No significant differences were found between surviving and control colonies for either grooming or VSH. Discussion Our data confirm that reduced mite reproductive success seems to be a key factor for natural survival of infested A. mellifera colonies. However, neither grooming nor VSH seem to explain colony survival. Instead, other behaviors of the adult bees seem to be sufficient to hinder mite reproductive success, because brood for this experiment was taken from susceptible donor colonies only. To mitigate the global impact of V. destructor, we suggest learning

  13. Norwegian honey bees surviving Varroa destructor mite infestations by means of natural selection.

    Science.gov (United States)

    Oddie, Melissa A Y; Dahle, Bjørn; Neumann, Peter

    2017-01-01

    Managed, feral and wild populations of European honey bee subspecies, Apis mellifera , are currently facing severe colony losses globally. There is consensus that the ectoparasitic mite Varroa destructor , that switched hosts from the Eastern honey bee Apis cerana to the Western honey bee A. mellifera , is a key factor driving these losses. For >20 years, breeding efforts have not produced European honey bee colonies that can survive infestations without the need for mite control. However, at least three populations of European honey bees have developed this ability by means of natural selection and have been surviving for >10 years without mite treatments. Reduced mite reproductive success has been suggested as a key factor explaining this natural survival. Here, we report a managed A. mellifera population in Norway, that has been naturally surviving consistent V. destructor infestations for >17 years. Surviving colonies and local susceptible controls were evaluated for mite infestation levels, mite reproductive success and two potential mechanisms explaining colony survival: grooming of adult worker bees and Varroa Sensitive Hygiene (VSH): adult workers specifically detecting and removing mite-infested brood. Mite infestation levels were significantly lower in surviving colonies and mite reproductive success was reduced by 30% when compared to the controls. No significant differences were found between surviving and control colonies for either grooming or VSH. Our data confirm that reduced mite reproductive success seems to be a key factor for natural survival of infested A. mellifera colonies. However, neither grooming nor VSH seem to explain colony survival. Instead, other behaviors of the adult bees seem to be sufficient to hinder mite reproductive success, because brood for this experiment was taken from susceptible donor colonies only. To mitigate the global impact of V. destructor , we suggest learning more from nature, i.e., identifying the obviously

  14. Natural selection and inheritance of breeding time and clutch size in the collared flycatcher.

    Science.gov (United States)

    Sheldon, B C; Kruuk, L E B; Merilä, J

    2003-02-01

    Many characteristics of organisms in free-living populations appear to be under directional selection, possess additive genetic variance, and yet show no evolutionary response to selection. Avian breeding time and clutch size are often-cited examples of such characters. We report analyses of inheritance of, and selection on, these traits in a long-term study of a wild population of the collared flycatcher Ficedula albicollis. We used mixed model analysis with REML estimation ("animal models") to make full use of the information in complex multigenerational pedigrees. Heritability of laying date, but not clutch size, was lower than that estimated previously using parent-offspring regressions, although for both traits there was evidence of substantial additive genetic variance (h2 = 0.19 and 0.29, respectively). Laying date and clutch size were negatively genetically correlated (rA = -0.41 +/- 0.09), implying that selection on one of the traits would cause a correlated response in the other, but there was little evidence to suggest that evolution of either trait would be constrained by correlations with other phenotypic characters. Analysis of selection on these traits in females revealed consistent strong directional fecundity selection for earlier breeding at the level of the phenotype (beta = -0.28 +/- 0.03), but little evidence for stabilising selection on breeding time. We found no evidence that clutch size was independently under selection. Analysis of fecundity selection on breeding values for laying date, estimated from an animal model, indicated that selection acts directly on additive genetic variance underlying breeding time (beta = -0.20 +/- 0.04), but not on clutch size (beta = 0.03 +/- 0.05). In contrast, selection on laying date via adult female survival fluctuated in sign between years, and was opposite in sign for selection on phenotypes (negative) and breeding values (positive). Our data thus suggest that any evolutionary response to selection on

  15. Present status of understanding on the G6PD deficiency and natural selection

    Directory of Open Access Journals (Sweden)

    Tripathy V

    2007-01-01

    Full Text Available G6PD deficiency is a common hemolytic genetic disorder, particularly in the areas endemic to malaria. Individuals are generally asymptomatic and hemolytic anemia occurs when some anti-malarial drugs or other oxidizing chemicals are administered. It has been proposed that G6PD deficiency provides protection against malaria. Maintaining of G6PD deficient alleles at polymorphic proportions is complicated because of the X-linked nature of G6PD deficiency. A comprehensive review of the literature on the hypothesis of malarial protection and the nature of the selection is being presented. Most of the epidemiological, in vitro and in vivo studies report selection for G6PD deficiency. Analysis of the G6PD gene also reveals that G6PD-deficient alleles show some signatures of selection. However, the question of how this polymorphism is being maintained remains unresolved because the selection/fitness coefficients for the different genotypes in the two sexes have not been established. Prevalence of G6PD deficiency in Indian caste and tribal populations and the different variants reported has also been reviewed.

  16. Adaptive evolution in locomotor performance: How selective pressures and functional relationships produce diversity.

    Science.gov (United States)

    Scales, Jeffrey A; Butler, Marguerite A

    2016-01-01

    Despite the complexity of nature, most comparative studies of phenotypic evolution consider selective pressures in isolation. When competing pressures operate on the same system, it is commonly expected that trade-offs will occur that will limit the evolution of phenotypic diversity, however, it is possible that interactions among selective pressures may promote diversity instead. We explored the evolution of locomotor performance in lizards in relation to possible selective pressures using the Ornstein-Uhlenbeck process. Here, we show that a combination of selection based on foraging mode and predator escape is required to explain variation in performance phenotypes. Surprisingly, habitat use contributed little explanatory power. We find that it is possible to evolve very different abilities in performance which were previously thought to be tightly correlated, supporting a growing literature that explores the many-to-one mapping of morphological design. Although we generally find the expected trade-off between maximal exertion and speed, this relationship surprisingly disappears when species experience selection for both performance types. We conclude that functional integration need not limit adaptive potential, and that an integrative approach considering multiple major influences on a phenotype allows a more complete understanding of adaptation and the evolution of diversity. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  17. The search for Pleiades in trait constellations: functional integration and phenotypic selection in the complex flowers of Morrenia brachystephana (Apocynaceae).

    Science.gov (United States)

    Baranzelli, M C; Sérsic, A N; Cocucci, A A

    2014-04-01

    Pollinator-mediated natural selection on single traits, such as corolla tube or spur length, has been well documented. However, flower phenotypes are usually complex, and selection is expected to act on several traits that functionally interact rather than on a single isolated trait. Despite the fact that selection on complex phenotypes is expectedly widespread, multivariate selection modelling on such phenotypes still remains under-explored in plants. Species of the subfamily Asclepiadoideae (Apocynaceae) provide an opportunity to study such complex flower contrivances integrated by fine-scaled organs from disparate developmental origin. We studied the correlation structure among linear floral traits (i) by testing a priori morphological, functional or developmental hypotheses among traits and (ii) by exploring the organization of flower covariation, considering alternative expectations of modular organization or whole flower integration through conditional dependence analysis (CDA) and integration matrices. The phenotypic selection approach was applied to determine whether floral traits involved in the functioning of the pollination mechanism were affected by natural selection. Floral integration was low, suggesting that flowers are organized in more than just one correlation pleiad; our hypothetical functional correlation matrix was significantly correlated with the empirical matrix, and the CDA revealed three putative modules. Analyses of phenotypic selection showed significant linear and correlational gradients, lending support to expectations of functional interactions between floral traits. Significant correlational selection gradients found involved traits of different floral whorls, providing evidence for the existence of functional integration across developmental domains. © 2014 The Authors. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

  18. Economic potential analysis of cogeneration using natural gas in the selected sectors; Analise do potencial economico de cogeracao a gas natural nos setores selecionados

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    This chapter presents the results of the economic potential of the natural gas cogeneration under topping regime, in the selected sectors of beverage industry, editorial and graphic industries, shopping centers, hospitals and hotels.

  19. Empirical tests of natural selection-based evolutionary accounts of ADHD: a systematic review.

    Science.gov (United States)

    Thagaard, Marthe S; Faraone, Stephen V; Sonuga-Barke, Edmund J; Østergaard, Søren D

    2016-10-01

    ADHD is a prevalent and highly heritable mental disorder associated with significant impairment, morbidity and increased rates of mortality. This combination of high prevalence and high morbidity/mortality seen in ADHD and other mental disorders presents a challenge to natural selection-based models of human evolution. Several hypotheses have been proposed in an attempt to resolve this apparent paradox. The aim of this study was to review the evidence for these hypotheses. We conducted a systematic review of the literature on empirical investigations of natural selection-based evolutionary accounts for ADHD in adherence with the PRISMA guideline. The PubMed, Embase, and PsycINFO databases were screened for relevant publications, by combining search terms covering evolution/selection with search terms covering ADHD. The search identified 790 records. Of these, 15 full-text articles were assessed for eligibility, and three were included in the review. Two of these reported on the evolution of the seven-repeat allele of the ADHD-associated dopamine receptor D4 gene, and one reported on the results of a simulation study of the effect of suggested ADHD-traits on group survival. The authors of the three studies interpreted their findings as favouring the notion that ADHD-traits may have been associated with increased fitness during human evolution. However, we argue that none of the three studies really tap into the core symptoms of ADHD, and that their conclusions therefore lack validity for the disorder. This review indicates that the natural selection-based accounts of ADHD have not been subjected to empirical test and therefore remain hypothetical.

  20. Measuring Knowledge of Natural Selection: A Comparison of the CINS, an Open-Response Instrument, and an Oral Interview

    Science.gov (United States)

    Nehm, Ross H.; Schonfeld, Irvin Sam

    2008-01-01

    Growing recognition of the central importance of fostering an in-depth understanding of natural selection has, surprisingly, failed to stimulate work on the development and rigorous evaluation of instruments that measure knowledge of it. We used three different methodological tools, the Conceptual Inventory of Natural Selection (CINS), a modified…

  1. Fisher's fundamental theorem of inclusive fitness and the change in fitness due to natural selection when conspecifics interact

    NARCIS (Netherlands)

    Bijma, P.

    2010-01-01

    Competition and cooperation is fundamental to evolution by natural selection, both in animals and plants. Here, I investigate the consequences of such interactions for response in fitness due to natural selection. I provide quantitative genetic expressions for heritable variance and response in

  2. Hydrogen selective membrane for the natural gas system. Development of CO{sub 2}-selective biogas membrane. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Vestboe, A.P.

    2012-02-15

    The project started as a literature study and technology development project for a hydrogen selective membrane for the natural gas system. The introduction of hydrogen (for example produced from wind turbines by surplus electricity) in the gas system makes it possible to store energy which can be selectively used with high energy conversion in fuel cells directly located at the end users. In order to make this possible, it is necessary to have a separating unit that can selectively remove hydrogen from the gas mixture and deliver it as fuel to the electrical generator (a fuel cell). In the project, several existing technologies were evaluated with regard to the application in view. It was concluded that while other technologies are ripe, they are costly in energy and unsuitable for the relatively low capacity application that are in question close to the end users. Membrane technology was evaluated to be the most suitable, although the technology is still under development in many cases. In the project it was found that metallic membranes in the form of palladium coated stainless discs would answer the needs for the high purity needed. Laboratory development yielded discs that could separate hydrogen from natural gas, however, the flux was low compared to the needs of the application. It was found that at least 2 bar pressure difference of hydrogen would be needed to get a high enough flux. The way to achieve this pressure would necessitate a compressor which would consume an energy amount high enough to invalidate the concept. When concluding on the results and the study it was found that the direction of the project could be changed towards developing CO{sub 2}-selective membranes with the goal of developing membrane technology that could upgrade biogas by removing CO{sub 2}. The laboratory equipment and setup that were developed in the first part of the project could be used directly in this second part of the project. In this second part of the project it was

  3. Natural selection underlies apparent stress-induced mutagenesis in a bacteriophage infection model.

    Science.gov (United States)

    Yosef, Ido; Edgar, Rotem; Levy, Asaf; Amitai, Gil; Sorek, Rotem; Munitz, Ariel; Qimron, Udi

    2016-04-18

    The emergence of mutations following growth-limiting conditions underlies bacterial drug resistance, viral escape from the immune system and fundamental evolution-driven events. Intriguingly, whether mutations are induced by growth limitation conditions or are randomly generated during growth and then selected by growth limitation conditions remains an open question(1). Here, we show that bacteriophage T7 undergoes apparent stress-induced mutagenesis when selected for improved recognition of its host's receptor. In our unique experimental set-up, the growth limitation condition is physically and temporally separated from mutagenesis: growth limitation occurs while phage DNA is outside the host, and spontaneous mutations occur during phage DNA replication inside the host. We show that the selected beneficial mutations are not pre-existing and that the initial slow phage growth is enabled by the phage particle's low-efficiency DNA injection into the host. Thus, the phage particle allows phage populations to initially extend their host range without mutagenesis by virtue of residual recognition of the host receptor. Mutations appear during non-selective intracellular replication, and the frequency of mutant phages increases by natural selection acting on free phages, which are not capable of mutagenesis.

  4. Active insecticides for Diaphania hyalinata selective for the natural enemy Solenopsis saevissima.

    Science.gov (United States)

    Aguiar, Alex R; Alvarenga, Elson S; Lopes, Mayara C; Santos, Izailda B Dos; Galdino, Tarcisio V; Picanço, Marcelo C

    2016-09-01

    The objective of this study was to determine the toxicity of the nine synthetic dienamides against the insect pest Diaphania hyalinata (melonworm) and the selectivity of these substances for the predator Solenopsis saevissima (fire ant). Four bioassays were conducted. To begin with, the dienamides that caused high mortality of D. hyalinata have been selected. In the second bioassay the dose-mortality curves of the selected dienamides have been constructed. In the third bioassay, the survival curves for D. hyalinata and the elapsed time to kill 50% of their population have been determined. In the fourth biological test, the selectivity of the substances to the predator S. saevissima has been evaluated. The most active (2E,4E)-N-butylhexa-2,4-dienamide 3d has killed 95% of the melonworm, D. hyalinata, and less than 10% of the natural enemy S. saevissima. The results presented by this compound are superior to the outcome displayed by the commercial insecticide Malathion®. Three of the dienamides prepared in this manuscript have proven to be selective in killing the pest, but not the beneficial insect.

  5. Natural Selection and Origin of a Melanistic Allele in North American Gray Wolves.

    Science.gov (United States)

    Schweizer, Rena M; Durvasula, Arun; Smith, Joel; Vohr, Samuel H; Stahler, Daniel R; Galaverni, Marco; Thalmann, Olaf; Smith, Douglas W; Randi, Ettore; Ostrander, Elaine A; Green, Richard E; Lohmueller, Kirk E; Novembre, John; Wayne, Robert K

    2018-05-01

    Pigmentation is often used to understand how natural selection affects genetic variation in wild populations since it can have a simple genetic basis, and can affect a variety of fitness-related traits (e.g., camouflage, thermoregulation, and sexual display). In gray wolves, the K locus, a β-defensin gene, causes black coat color via a dominantly inherited KB allele. The allele is derived from dog-wolf hybridization and is at high frequency in North American wolf populations. We designed a DNA capture array to probe the geographic origin, age, and number of introgression events of the KB allele in a panel of 331 wolves and 20 dogs. We found low diversity in KB, but not ancestral ky, wolf haplotypes consistent with a selective sweep of the black haplotype across North America. Further, North American wolf KB haplotypes are monophyletic, suggesting that a single adaptive introgression from dogs to wolves most likely occurred in the Northwest Territories or Yukon. We use a new analytical approach to date the origin of the KB allele in Yukon wolves to between 1,598 and 7,248 years ago, suggesting that introgression with early Native American dogs was the source. Using population genetic simulations, we show that the K locus is undergoing natural selection in four wolf populations. We find evidence for balancing selection, specifically in Yellowstone wolves, which could be a result of selection for enhanced immunity in response to distemper. With these data, we demonstrate how the spread of an adaptive variant may have occurred across a species' geographic range.

  6. Natural cytolytic activity in mice with natural or induced cellular defects. I. Differential ability of in vitro interleukin-2 addition to augment natural cytolytic function

    International Nuclear Information System (INIS)

    Ades, E.W.; Hinson, A.; Butler, L.D.

    1986-01-01

    The ability of in vitro addition of recombinant interleukin 2 (rIL-2) to differentially enhance natural cytotoxicity was assessed using cells from mice with natural and induced cellular defects. In vivo treatment with most immunosuppressive or cytoreductive agents, anti-asialo-GM1 antibody, or gamma irradiation dramatically reduced in vitro cytotoxicity against natural killer (NK) sensitive targets by direct reduction in either percentage specific lysis or lytic units per spleen. In most cases, in vitro addition of rIL-2 (at concentrations causing augmented NK function in cells from naive Balb/C mice) enhanced cytotoxic activity of cells from treatment groups to a normal value but not within the rIL-2-enhanced range of nontreated animals. Additionally, cytotoxic activity of cells from animals treated with certain drugs or gamma irradiation could be augmented by rIL-2 when measured by percentage lysis but not lytic units per spleen. In vivo treatment with cyclosporin A did not affect natural cytotoxic activity and addition of rIL-2 augmented the NK activity in a similar fashion to the profile of naive cells. In experiments using cells from beige (C57Bl/6-bg) mice which have a natural defect in NK activity against YAC-1 targets, addition of rIL-2 (at concentrations causing augmented natural cytotoxic function in cells from C57Bl/6 mice) could not effectively enhance in vitro natural cytotoxic function

  7. Natural cytolytic activity in mice with natural or induced cellular defects. I. Differential ability of in vitro interleukin-2 addition to augment natural cytolytic function

    Energy Technology Data Exchange (ETDEWEB)

    Ades, E.W.; Hinson, A.; Butler, L.D.

    1986-08-01

    The ability of in vitro addition of recombinant interleukin 2 (rIL-2) to differentially enhance natural cytotoxicity was assessed using cells from mice with natural and induced cellular defects. In vivo treatment with most immunosuppressive or cytoreductive agents, anti-asialo-GM1 antibody, or gamma irradiation dramatically reduced in vitro cytotoxicity against natural killer (NK) sensitive targets by direct reduction in either percentage specific lysis or lytic units per spleen. In most cases, in vitro addition of rIL-2 (at concentrations causing augmented NK function in cells from naive Balb/C mice) enhanced cytotoxic activity of cells from treatment groups to a normal value but not within the rIL-2-enhanced range of nontreated animals. Additionally, cytotoxic activity of cells from animals treated with certain drugs or gamma irradiation could be augmented by rIL-2 when measured by percentage lysis but not lytic units per spleen. In vivo treatment with cyclosporin A did not affect natural cytotoxic activity and addition of rIL-2 augmented the NK activity in a similar fashion to the profile of naive cells. In experiments using cells from beige (C57Bl/6-bg) mice which have a natural defect in NK activity against YAC-1 targets, addition of rIL-2 (at concentrations causing augmented natural cytotoxic function in cells from C57Bl/6 mice) could not effectively enhance in vitro natural cytotoxic function.

  8. Population genetic structure and natural selection of apical membrane antigen-1 in Plasmodium vivax Korean isolates.

    Science.gov (United States)

    Kang, Jung-Mi; Lee, Jinyoung; Cho, Pyo-Yun; Moon, Sung-Ung; Ju, Hye-Lim; Ahn, Seong Kyu; Sohn, Woon-Mok; Lee, Hyeong-Woo; Kim, Tong-Soo; Na, Byoung-Kuk

    2015-11-16

    Plasmodium vivax apical membrane antigen-1 (PvAMA-1) is a leading candidate antigen for blood stage malaria vaccine. However, antigenic variation is a major obstacle in the development of an effective vaccine based on this antigen. In this study, the genetic structure and the effect of natural selection of PvAMA-1 among Korean P. vivax isolates were analysed. Blood samples were collected from 66 Korean patients with vivax malaria. The entire PvAMA-1 gene was amplified by polymerase chain reaction and cloned into a TA cloning vector. The PvAMA-1 sequence of each isolate was sequenced and the polymorphic characteristics and effect of natural selection were analysed using the DNASTAR, MEGA4, and DnaSP programs. Thirty haplotypes of PvAMA-1, which were further classified into seven different clusters, were identified in the 66 Korean P. vivax isolates. Domain II was highly conserved among the sequences, but substantial nucleotide diversity was observed in domains I and III. The difference between the rates of non-synonymous and synonymous mutations suggested that the gene has evolved under natural selection. No strong evidence indicating balancing or positive selection on PvAMA-1 was identified. Recombination may also play a role in the resulting genetic diversity of PvAMA-1. This study is the first comprehensive analysis of nucleotide diversity across the entire PvAMA-1 gene using a single population sample from Korea. Korean PvAMA-1 had limited genetic diversity compared to PvAMA-1 in global isolates. The overall pattern of genetic polymorphism of Korean PvAMA-1 differed from other global isolates and novel amino acid changes were also identified in Korean PvAMA-1. Evidences for natural selection and recombination event were observed, which is likely to play an important role in generating genetic diversity across the PvAMA-1. These results provide useful information for the understanding the population structure of P. vivax circulating in Korea and have important

  9. Genome-wide Selective Sweeps in Natural Bacterial Populations Revealed by Time-series Metagenomics

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Leong-Keat; Bendall, Matthew L.; Malfatti, Stephanie; Schwientek, Patrick; Tremblay, Julien; Schackwitz, Wendy; Martin, Joel; Pati, Amrita; Bushnell, Brian; Foster, Brian; Kang, Dongwan; Tringe, Susannah G.; Bertilsson, Stefan; Moran, Mary Ann; Shade, Ashley; Newton, Ryan J.; Stevens, Sarah; McMcahon, Katherine D.; Mamlstrom, Rex R.

    2014-05-12

    Multiple evolutionary models have been proposed to explain the formation of genetically and ecologically distinct bacterial groups. Time-series metagenomics enables direct observation of evolutionary processes in natural populations, and if applied over a sufficiently long time frame, this approach could capture events such as gene-specific or genome-wide selective sweeps. Direct observations of either process could help resolve how distinct groups form in natural microbial assemblages. Here, from a three-year metagenomic study of a freshwater lake, we explore changes in single nucleotide polymorphism (SNP) frequencies and patterns of gene gain and loss in populations of Chlorobiaceae and Methylophilaceae. SNP analyses revealed substantial genetic heterogeneity within these populations, although the degree of heterogeneity varied considerably among closely related, co-occurring Methylophilaceae populations. SNP allele frequencies, as well as the relative abundance of certain genes, changed dramatically over time in each population. Interestingly, SNP diversity was purged at nearly every genome position in one of the Chlorobiaceae populations over the course of three years, while at the same time multiple genes either swept through or were swept from this population. These patterns were consistent with a genome-wide selective sweep, a process predicted by the ecotype model? of diversification, but not previously observed in natural populations.

  10. Genome-wide Selective Sweeps in Natural Bacterial Populations Revealed by Time-series Metagenomics

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Leong-Keat; Bendall, Matthew L.; Malfatti, Stephanie; Schwientek, Patrick; Tremblay, Julien; Schackwitz, Wendy; Martin, Joel; Pati, Amrita; Bushnell, Brian; Foster, Brian; Kang, Dongwan; Tringe, Susannah G.; Bertilsson, Stefan; Moran, Mary Ann; Shade, Ashley; Newton, Ryan J.; Stevens, Sarah; McMahon, Katherine D.; Malmstrom, Rex R.

    2014-06-18

    Multiple evolutionary models have been proposed to explain the formation of genetically and ecologically distinct bacterial groups. Time-series metagenomics enables direct observation of evolutionary processes in natural populations, and if applied over a sufficiently long time frame, this approach could capture events such as gene-specific or genome-wide selective sweeps. Direct observations of either process could help resolve how distinct groups form in natural microbial assemblages. Here, from a three-year metagenomic study of a freshwater lake, we explore changes in single nucleotide polymorphism (SNP) frequencies and patterns of gene gain and loss in populations of Chlorobiaceae and Methylophilaceae. SNP analyses revealed substantial genetic heterogeneity within these populations, although the degree of heterogeneity varied considerably among closely related, co-occurring Methylophilaceae populations. SNP allele frequencies, as well as the relative abundance of certain genes, changed dramatically over time in each population. Interestingly, SNP diversity was purged at nearly every genome position in one of the Chlorobiaceae populations over the course of three years, while at the same time multiple genes either swept through or were swept from this population. These patterns were consistent with a genome-wide selective sweep, a process predicted by the ‘ecotype model’ of diversification, but not previously observed in natural populations.

  11. Evidence of natural selection acting on a polymorphic hybrid incompatibility locus in Mimulus.

    Science.gov (United States)

    Sweigart, Andrea L; Flagel, Lex E

    2015-02-01

    As a common cause of reproductive isolation in diverse taxa, hybrid incompatibilities are fundamentally important to speciation. A key question is which evolutionary forces drive the initial substitutions within species that lead to hybrid dysfunction. Previously, we discovered a simple genetic incompatibility that causes nearly complete male sterility and partial female sterility in hybrids between the two closely related yellow monkeyflower species Mimulus guttatus and M. nasutus. In this report, we fine map the two major incompatibility loci-hybrid male sterility 1 (hms1) and hybrid male sterility 2 (hms2)-to small nuclear genomic regions (each <70 kb) that include strong candidate genes. With this improved genetic resolution, we also investigate the evolutionary dynamics of hms1 in a natural population of M. guttatus known to be polymorphic at this locus. Using classical genetic crosses and population genomics, we show that a 320-kb region containing the hms1 incompatibility allele has risen to intermediate frequency in this population by strong natural selection. This finding provides direct evidence that natural selection within plant species can lead to hybrid dysfunction between species. Copyright © 2015 by the Genetics Society of America.

  12. Natural selection on MHC IIβ in parapatric lake and stream stickleback: Balancing, divergent, both or neither?

    Science.gov (United States)

    Stutz, William E; Bolnick, Daniel I

    2017-09-01

    Major histocompatibility complex (MHC) genes encode proteins that play a central role in vertebrates' adaptive immunity to parasites. MHC loci are among the most polymorphic in vertebrates' genomes, inspiring many studies to identify evolutionary processes driving MHC polymorphism within populations and divergence between populations. Leading hypotheses include balancing selection favouring rare alleles within populations, and spatially divergent selection. These hypotheses do not always produce diagnosably distinct predictions, causing many studies of MHC to yield inconsistent or ambiguous results. We suggest a novel strategy to distinguish balancing vs. divergent selection on MHC, taking advantage of natural admixture between parapatric populations. With divergent selection, individuals with immigrant alleles will be more infected and less fit because they are susceptible to novel parasites in their new habitat. With balancing selection, individuals with locally rare immigrant alleles will be more fit (less infected). We tested these contrasting predictions using three-spine stickleback from three replicate pairs of parapatric lake and stream habitats. We found numerous positive and negative associations between particular MHC IIβ alleles and particular parasite taxa. A few allele-parasite comparisons supported balancing selection, and others supported divergent selection between habitats. But, there was no overall tendency for fish with immigrant MHC alleles to be more or less heavily infected. Instead, locally rare MHC alleles (not necessarily immigrants) were associated with heavier infections. Our results illustrate the complex relationship between MHC IIβ allelic variation and spatially varying multispecies parasite communities: different hypotheses may be concurrently true for different allele-parasite combinations. © 2017 John Wiley & Sons Ltd.

  13. Patterns of population differentiation and natural selection on the celiac disease background risk network.

    Science.gov (United States)

    Sams, Aaron; Hawks, John

    2013-01-01

    Celiac disease is a common small intestinal inflammatory condition induced by wheat gluten and related proteins from rye and barley. Left untreated, the clinical presentation of CD can include failure to thrive, malnutrition, and distension in juveniles. The disease can additionally lead to vitamin deficiencies, anemia, and osteoporosis. Therefore, CD potentially negatively affected fitness in past populations utilizing wheat, barley, and rye. Previous analyses of CD risk variants have uncovered evidence for positive selection on some of these loci. These studies also suggest the possibility that risk for common autoimmune conditions such as CD may be the result of positive selection on immune related loci in the genome to fight infection. Under this evolutionary scenario, disease phenotypes may be a trade-off from positive selection on immunity. If this hypothesis is generally true, we can expect to find a signal of natural selection when we survey across the network of loci known to influence CD risk. This study examines the non-HLA autosomal network of gene loci associated with CD risk in Europe. We reject the null hypothesis of neutrality on this network of CD risk loci. Additionally, we can localize evidence of selection in time and space by adding information from the genome of the Tyrolean Iceman. While we can show significant differentiation between continental regions across the CD network, the pattern of evidence is not consistent with primarily recent (Holocene) selection across this network in Europe. Further localization of ancient selection on this network may illuminate the ecological pressures acting on the immune system during this critically interesting phase of our evolution.

  14. Patterns of population differentiation and natural selection on the celiac disease background risk network.

    Directory of Open Access Journals (Sweden)

    Aaron Sams

    Full Text Available Celiac disease is a common small intestinal inflammatory condition induced by wheat gluten and related proteins from rye and barley. Left untreated, the clinical presentation of CD can include failure to thrive, malnutrition, and distension in juveniles. The disease can additionally lead to vitamin deficiencies, anemia, and osteoporosis. Therefore, CD potentially negatively affected fitness in past populations utilizing wheat, barley, and rye. Previous analyses of CD risk variants have uncovered evidence for positive selection on some of these loci. These studies also suggest the possibility that risk for common autoimmune conditions such as CD may be the result of positive selection on immune related loci in the genome to fight infection. Under this evolutionary scenario, disease phenotypes may be a trade-off from positive selection on immunity. If this hypothesis is generally true, we can expect to find a signal of natural selection when we survey across the network of loci known to influence CD risk. This study examines the non-HLA autosomal network of gene loci associated with CD risk in Europe. We reject the null hypothesis of neutrality on this network of CD risk loci. Additionally, we can localize evidence of selection in time and space by adding information from the genome of the Tyrolean Iceman. While we can show significant differentiation between continental regions across the CD network, the pattern of evidence is not consistent with primarily recent (Holocene selection across this network in Europe. Further localization of ancient selection on this network may illuminate the ecological pressures acting on the immune system during this critically interesting phase of our evolution.

  15. DETECTING SELECTION IN NATURAL POPULATIONS: MAKING SENSE OF GENOME SCANS AND TOWARDS ALTERNATIVE SOLUTIONS

    Science.gov (United States)

    Haasl, Ryan J.; Payseur, Bret A.

    2016-01-01

    Genomewide scans for natural selection (GWSS) have become increasingly common over the last 15 years due to increased availability of genome-scale genetic data. Here, we report a representative survey of GWSS from 1999 to present and find that (i) between 1999 and 2009, 35 of 49 (71%) GWSS focused on human, while from 2010 to present, only 38 of 83 (46%) of GWSS focused on human, indicating increased focus on nonmodel organisms; (ii) the large majority of GWSS incorporate interpopulation or interspecific comparisons using, for example FST, cross-population extended haplotype homozygosity or the ratio of nonsynonymous to synonymous substitutions; (iii) most GWSS focus on detection of directional selection rather than other modes such as balancing selection; and (iv) in human GWSS, there is a clear shift after 2004 from microsatellite markers to dense SNP data. A survey of GWSS meant to identify loci positively selected in response to severe hypoxic conditions support an approach to GWSS in which a list of a priori candidate genes based on potential selective pressures are used to filter the list of significant hits a posteriori. We also discuss four frequently ignored determinants of genomic heterogeneity that complicate GWSS: mutation, recombination, selection and the genetic architecture of adaptive traits. We recommend that GWSS methodology should better incorporate aspects of genomewide heterogeneity using empirical estimates of relevant parameters and/or realistic, whole-chromosome simulations to improve interpretation of GWSS results. Finally, we argue that knowledge of potential selective agents improves interpretation of GWSS results and that new methods focused on correlations between environmental variables and genetic variation can help automate this approach. PMID:26224644

  16. Strong and consistent natural selection associated with armour reduction in sticklebacks.

    Science.gov (United States)

    LE Rouzic, Arnaud; Østbye, Kjartan; Klepaker, Tom O; Hansen, Thomas F; Bernatchez, Louis; Schluter, Dolph; Vøllestad, L Asbjørn

    2011-06-01

    Measuring the strength of natural selection is tremendously important in evolutionary biology, but remains a challenging task. In this work, we analyse the characteristics of selection for a morphological change (lateral-plate reduction) in the threespine stickleback Gasterosteus aculeatus. Adaptation to freshwater, leading with the reduction or loss of the bony lateral armour, has occurred in parallel on numerous occasions in this species. Completely-plated and low-plated sticklebacks were introduced into a pond, and the phenotypic changes were tracked for 20 years. Fish from the last generation were genotyped for the Ectodysplasin-A (Eda) locus, the major gene involved in armour development. We found a strong fitness advantage for the freshwater-type fish (on average, 20% fitness advantage for the freshwater morph, and 92% for the freshwater genotype). The trend is best explained by assuming that this fitness advantage is maximum at the beginning of the invasion and decreases with time. Such fitness differences provide a quantifiable example of rapid selection-driven phenotypic evolution associated with environmental change in a natural population. © 2011 Blackwell Publishing Ltd.

  17. 29 CFR 452.20 - Nature of executive functions.

    Science.gov (United States)

    2010-07-01

    ... functions of treasurer if he has principal responsibility for control and management of the organization's... Regulations Relating to Labor OFFICE OF LABOR-MANAGEMENT STANDARDS, DEPARTMENT OF LABOR LABOR-MANAGEMENT STANDARDS GENERAL STATEMENT CONCERNING THE ELECTION PROVISIONS OF THE LABOR-MANAGEMENT REPORTING AND...

  18. Effects of ultraviolet irradiation on natural killer cell function in systemic lupus erythematosus

    Energy Technology Data Exchange (ETDEWEB)

    Nived, O.; Johansson, I.; Sturfelt, G. (University Hospital, Lund (Sweden). Dept. of Rheumatology)

    1992-06-01

    In vitro irradiation with long wavelength ultraviolet light (UV-A), in clinically relevant dosages, of a natural killer cell line containing cell preparations from 17 control subjects reduced natural killer cell cytotoxicity with the cell line K562 as target. The spontaneous function of natural killer cells from 12 patients with systematic lupus erythematosus (SLE) correlated inversely with the one hour erythrocyte sedimentation rate, but not with glucocorticoid doses. After UV-A exposure, natural killer cells from patients with SLE exert either increased or decreased cytotoxicity, and the direction of change is inversely correlated with the spontaneous natural killer cell function. (Author).

  19. Effects of ultraviolet irradiation on natural killer cell function in systemic lupus erythematosus

    International Nuclear Information System (INIS)

    Nived, O.; Johansson, I.; Sturfelt, G.

    1992-01-01

    In vitro irradiation with long wavelength ultraviolet light (UV-A), in clinically relevant dosages, of a natural killer cell line containing cell preparations from 17 control subjects reduced natural killer cell cytotoxicity with the cell line K562 as target. The spontaneous function of natural killer cells from 12 patients with systematic lupus erythematosus (SLE) correlated inversely with the one hour erythrocyte sedimentation rate, but not with glucocorticoid doses. After UV-A exposure, natural killer cells from patients with SLE exert either increased or decreased cytotoxicity, and the direction of change is inversely correlated with the spontaneous natural killer cell function. (Author)

  20. Comparison of Selected Functions of Scopus and Web of Science

    Directory of Open Access Journals (Sweden)

    Tomaž Bartol

    2013-09-01

    been accessible for many years. Scopus Trial has only become available during the last year. Comparison of both databases focuses on functional characteristics. Principal current functions of both search systems are assessed (as of the second half of the year 2011. Search possibilities are compared e.g. (Document Search based on the selection of fields from pull down menus, and Advanced Search, requiring the application of search-operators. Limits, arrangement of records (Sort by, and advanced analytics (Analyze/Refineare evaluated, with some emphasize on citations (Cited Reference Search. The new WoS interface (essentially retains the previous arrangement of tasks, adding some novel functions and possibilities. Lemmatization can be turned off. Cited-reference searchin WoS remains easy, it is principally based on the author search, with the authority control for author-sets, however, still somehow weak. Unique author sets are frequently hard to define. Scopus offers complex search possibilities for a veryhigh number of fields, including the All Fields search, and the Reference title search. Unique authors seem to be grouped together more consistently in Scopus. However, the same authors can still come about in different sets. Also, stemming (lemmatization can not be turned off in Scopus. This analysis as well as the review of literature, substantiate the need for concurrent use of both databases, in order to obtain optimal search results. Nevertheless, the complexity of both information systems requires advanced information competency of end-users.

  1. How nature designs light-harvesting antenna systems: design principles and functional realization in chlorophototrophic prokaryotes

    Science.gov (United States)

    Bryant, Donald A.; Canniffe, Daniel P.

    2018-02-01

    Chlorophyll-based phototrophs, or chlorophototrophs, convert light energy into stored chemical potential energy using two types of photochemical reaction center (RC), denoted type-1 and type-2. After excitation with light, a so-called special pair of chlorophylls in the RC is oxidized, and an acceptor is reduced. To ensure that RCs function at maximal rates in diffuse and variable light conditions, chlorophototrophs have independently evolved diverse light-harvesting antenna systems to rapidly and efficiently transfer that energy to the RCs. Energy transfer between weakly coupled chromophores is generally believed to proceed by resonance energy transfer, a dipole-induced-dipole process that was initially described theoretically by Förster. Nature principally optimizes three parameters in antenna systems: the distance separating the donor and acceptor chromophores, the relative orientations of those chromophores, and the spectral overlap between the donor and the acceptor chromophores. However, there are other important biological parameters that nature has optimized, and some common themes emerge from comparisons of different antenna systems. This tutorial considers structural and functional characteristics of three fundamentally different light-harvesting antenna systems of chlorophotrophic bacteria: phycobilisomes of cyanobacteria, the light-harvesting complexes (LH1 and LH2) of purple bacteria, and chlorosomes of green bacteria. Phycobilisomes are generally considered to represent an antenna system in which the chromophores are weakly coupled, while the strongly coupled bacteriochlorophyll molecules in LH1 and LH2 are strongly coupled and are better described by exciton theory. Chlorosomes can contain up to 250 000 bacteriochlorophyll molecules, which are very strongly coupled and form supramolecular, nanotubular arrays. The general and specific principles that have been optimized by natural selection during the evolution of these diverse light

  2. Natural gas market - Market opening in Switzerland and a selection of European Union countries

    International Nuclear Information System (INIS)

    Wild, J.; Vaterlaus, S.; Worm, H.; Spielmann, Ch.; Finger, M.

    2007-02-01

    This comprehensive report for the Swiss Federal Office of Energy (SFOE) takes a look at the situation in Switzerland and Europe as far as the liberalisation of the natural gas market is concerned. Comparisons are made between the situation for natural gas and electricity markets. The report discusses the economical and technical characteristics of the gas business such as gas sources, transport, storage and trading as well as the associated investment risks. The gas and electricity supply systems are compared from the supply and demand viewpoints and as far as trading and the increasing of efficiency are concerned. The Swiss gas market is compared with those of selected European countries. Market structures and regulatory aspects are examined and the resulting effects on the market and gas prices are reviewed. The effects of market opening are discussed from both the supplier and consumer points of view

  3. Environmental cost-effectiveness analysis in intertemporal natural resource policy: evaluation of selective fishing gear.

    Science.gov (United States)

    Kronbak, Lone Grønbæk; Vestergaard, Niels

    2013-12-15

    In most decision-making involving natural resources, the achievements of a given policy (e.g., improved ecosystem or biodiversity) are rather difficult to measure in monetary units. To address this problem, the current paper develops an environmental cost-effectiveness analysis (ECEA) to include intangible benefits in intertemporal natural resource problems. This approach can assist managers in prioritizing management actions as least cost solutions to achieve quantitative policy targets. The ECEA framework is applied to a selective gear policy case in Danish mixed trawl fisheries in Kattegat and Skagerrak. The empirical analysis demonstrates how a policy with large negative net benefits might be justified if the intangible benefits are included. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Exploiting Submodular Value Functions for Faster Dynamic Sensor Selection

    NARCIS (Netherlands)

    Satsangi, Y.; Whiteson, S.; Oliehoek, F.A.

    2015-01-01

    A key challenge in the design of multi-sensor systems is the efficient allocation of scarce resources such as bandwidth, CPU cycles, and energy, leading to the dynamic sensor selection problem in which a subset of the available sensors must be selected at each timestep. While partially observable

  5. Evolvability Is an Evolved Ability: The Coding Concept as the Arch-Unit of Natural Selection.

    Science.gov (United States)

    Janković, Srdja; Ćirković, Milan M

    2016-03-01

    Physical processes that characterize living matter are qualitatively distinct in that they involve encoding and transfer of specific types of information. Such information plays an active part in the control of events that are ultimately linked to the capacity of the system to persist and multiply. This algorithmicity of life is a key prerequisite for its Darwinian evolution, driven by natural selection acting upon stochastically arising variations of the encoded information. The concept of evolvability attempts to define the total capacity of a system to evolve new encoded traits under appropriate conditions, i.e., the accessible section of total morphological space. Since this is dependent on previously evolved regulatory networks that govern information flow in the system, evolvability itself may be regarded as an evolved ability. The way information is physically written, read and modified in living cells (the "coding concept") has not changed substantially during the whole history of the Earth's biosphere. This biosphere, be it alone or one of many, is, accordingly, itself a product of natural selection, since the overall evolvability conferred by its coding concept (nucleic acids as information carriers with the "rulebook of meanings" provided by codons, as well as all the subsystems that regulate various conditional information-reading modes) certainly played a key role in enabling this biosphere to survive up to the present, through alterations of planetary conditions, including at least five catastrophic events linked to major mass extinctions. We submit that, whatever the actual prebiotic physical and chemical processes may have been on our home planet, or may, in principle, occur at some time and place in the Universe, a particular coding concept, with its respective potential to give rise to a biosphere, or class of biospheres, of a certain evolvability, may itself be regarded as a unit (indeed the arch-unit) of natural selection.

  6. Logos and Logoi in Plotinus. Their nature and Function

    Directory of Open Access Journals (Sweden)

    Brisson, Luc

    2009-06-01

    Full Text Available The universe is the result of a production that pertains not to craft, but to nature. This production does not involve either reasoning or concepts, but is the result of a power that acts on matter like an imprint. The Intellect transmits the intelligible forms it harbors, to the hypostasis Soul, where they become rational formulas (logoi. The hypostasis Soul then transmits these rational formulas to the world soul, which produces animate and inanimate beings, as if it had been ordered to do so. Yet since it is the lower part of the soul of the world that is responsible for these productions, its action, which depends on reasons that do not hold the first rank and are drawn from itself, manifests inferior quality, which explains imperfection and the presence of evil in the sensible universe, despite its government by Providence.

  7. Interaction-based evolution: how natural selection and nonrandom mutation work together

    Science.gov (United States)

    2013-01-01

    Background The modern evolutionary synthesis leaves unresolved some of the most fundamental, long-standing questions in evolutionary biology: What is the role of sex in evolution? How does complex adaptation evolve? How can selection operate effectively on genetic interactions? More recently, the molecular biology and genomics revolutions have raised a host of critical new questions, through empirical findings that the modern synthesis fails to explain: for example, the discovery of de novo genes; the immense constructive role of transposable elements in evolution; genetic variance and biochemical activity that go far beyond what traditional natural selection can maintain; perplexing cases of molecular parallelism; and more. Presentation of the hypothesis Here I address these questions from a unified perspective, by means of a new mechanistic view of evolution that offers a novel connection between selection on the phenotype and genetic evolutionary change (while relying, like the traditional theory, on natural selection as the only source of feedback on the fit between an organism and its environment). I hypothesize that the mutation that is of relevance for the evolution of complex adaptation—while not Lamarckian, or “directed” to increase fitness—is not random, but is instead the outcome of a complex and continually evolving biological process that combines information from multiple loci into one. This allows selection on a fleeting combination of interacting alleles at different loci to have a hereditary effect according to the combination’s fitness. Testing and implications of the hypothesis This proposed mechanism addresses the problem of how beneficial genetic interactions can evolve under selection, and also offers an intuitive explanation for the role of sex in evolution, which focuses on sex as the generator of genetic combinations. Importantly, it also implies that genetic variation that has appeared neutral through the lens of traditional

  8. Natural selection interacts with recombination to shape the evolution of hybrid genomes.

    Science.gov (United States)

    Schumer, Molly; Xu, Chenling; Powell, Daniel L; Durvasula, Arun; Skov, Laurits; Holland, Chris; Blazier, John C; Sankararaman, Sriram; Andolfatto, Peter; Rosenthal, Gil G; Przeworski, Molly

    2018-05-11

    To investigate the consequences of hybridization between species, we studied three replicate hybrid populations that formed naturally between two swordtail fish species, estimating their fine-scale genetic map and inferring ancestry along the genomes of 690 individuals. In all three populations, ancestry from the "minor" parental species is more common in regions of high recombination and where there is linkage to fewer putative targets of selection. The same patterns are apparent in a reanalysis of human and archaic admixture. These results support models in which ancestry from the minor parental species is more likely to persist when rapidly uncoupled from alleles that are deleterious in hybrids. Our analyses further indicate that selection on swordtail hybrids stems predominantly from deleterious combinations of epistatically interacting alleles. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  9. Selective catalytic reduction of nitric oxide by ammonia over Cu-exchanged Cuban natural zeolites

    International Nuclear Information System (INIS)

    Moreno-Tost, Ramon; Santamaria-Gonzalez, Jose; Rodriguez-Castellon, Enrique; Jimenez-Lopez, Antonio; Autie, Miguel A.; Glacial, Marisol Carreras; Gonzalez, Edel; Pozas, Carlos De las

    2004-01-01

    The catalytic selective reduction of NO over Cu-exchanged natural zeolites (mordenite (MP) and clinoptilolite (HC)) from Cuba using NH 3 as reducing agent and in the presence of excess oxygen was studied. Cu(II)-exchanged zeolites are very active catalysts, with conversions of NO of 95%, a high selectivity to N 2 at low temperatures, and exhibiting good water tolerance. The chemical state of the Cu(II) in exchanged zeolites was characterized by H 2 -TPR and XPS. Cu(II)-exchanged clinoptilolite underwent a severe deactivation in the presence of SO 2 . However, Cu(II)-exchanged mordenite not only maintained its catalytic activity, but even showed a slight improvement after 20h of reaction in the presence of 100ppm of SO 2

  10. The transition to modernity and chronic disease: mismatch and natural selection.

    Science.gov (United States)

    Corbett, Stephen; Courtiol, Alexandre; Lummaa, Virpi; Moorad, Jacob; Stearns, Stephen

    2018-05-09

    The Industrial Revolution and the accompanying nutritional, epidemiological and demographic transitions have profoundly changed human ecology and biology, leading to major shifts in life history traits, which include age and size at maturity, age-specific fertility and lifespan. Mismatch between past adaptations and the current environment means that gene variants linked to higher fitness in the past may now, through antagonistic pleiotropic effects, predispose post-transition populations to non-communicable diseases, such as Alzheimer disease, cancer and coronary artery disease. Increasing evidence suggests that the transition to modernity has also altered the direction and intensity of natural selection acting on many traits, with important implications for public and global health.

  11. Genomic signatures of geographic isolation and natural selection in coral reef fishes.

    Science.gov (United States)

    Gaither, Michelle R; Bernal, Moisés A; Coleman, Richard R; Bowen, Brian W; Jones, Shelley A; Simison, W Brian; Rocha, Luiz A

    2015-04-01

    The drivers of speciation remain among the most controversial topics in evolutionary biology. Initially, Darwin emphasized natural selection as a primary mechanism of speciation, but the architects of the modern synthesis largely abandoned that view in favour of divergence by geographic isolation. The balance between selection and isolation is still at the forefront of the evolutionary debate, especially for the world's tropical oceans where biodiversity is high, but isolating barriers are few. Here, we identify the drivers of speciation in Pacific reef fishes of the genus Acanthurus by comparative genome scans of two peripheral populations that split from a large Central-West Pacific lineage at roughly the same time. Mitochondrial sequences indicate that populations in the Hawaiian Archipelago and the Marquesas Islands became isolated approximately 0.5 Ma. The Hawaiian lineage is morphologically indistinguishable from the widespread Pacific form, but the Marquesan form is recognized as a distinct species that occupies an unusual tropical ecosystem characterized by upwelling, turbidity, temperature fluctuations, algal blooms and little coral cover. An analysis of 3737 SNPs reveals a strong signal of selection at the Marquesas, with 59 loci under disruptive selection including an opsin Rh2 locus. While both the Hawaiian and Marquesan populations indicate signals of drift, the former shows a weak signal of selection that is comparable with populations in the Central-West Pacific. This contrast between closely related lineages reveals one population diverging due primarily to geographic isolation and genetic drift, and the other achieving taxonomic species status under the influence of selection. © 2015 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

  12. Natural selection on individual variation in tolerance of gastrointestinal nematode infection.

    Directory of Open Access Journals (Sweden)

    Adam D Hayward

    2014-07-01

    Full Text Available Hosts may mitigate the impact of parasites by two broad strategies: resistance, which limits parasite burden, and tolerance, which limits the fitness or health cost of increasing parasite burden. The degree and causes of variation in both resistance and tolerance are expected to influence host-parasite evolutionary and epidemiological dynamics and inform disease management, yet very little empirical work has addressed tolerance in wild vertebrates. Here, we applied random regression models to longitudinal data from an unmanaged population of Soay sheep to estimate individual tolerance, defined as the rate of decline in body weight with increasing burden of highly prevalent gastrointestinal nematode parasites. On average, individuals lost weight as parasite burden increased, but whereas some lost weight slowly as burden increased (exhibiting high tolerance, other individuals lost weight significantly more rapidly (exhibiting low tolerance. We then investigated associations between tolerance and fitness using selection gradients that accounted for selection on correlated traits, including body weight. We found evidence for positive phenotypic selection on tolerance: on average, individuals who lost weight more slowly with increasing parasite burden had higher lifetime breeding success. This variation did not have an additive genetic basis. These results reveal that selection on tolerance operates under natural conditions. They also support theoretical predictions for the erosion of additive genetic variance of traits under strong directional selection and fixation of genes conferring tolerance. Our findings provide the first evidence of selection on individual tolerance of infection in animals and suggest practical applications in animal and human disease management in the face of highly prevalent parasites.

  13. The use of naturally occurring selectively isolated bacteria for inhibiting paraffin deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lazar, I.; Voicu, A.; Dobrota, S.; Petrisor, I.G.; Stefanescu, M.; Sandulescu, L. [Institute of Biology of the Romanian Academy, Spl. Independentei 296, Bucharest (Romania); Nicolescu, C.; Mucenica, D. [PETROSTAR Ploiesti, Bdul Bucuresti 35, Ploiesti (Romania)

    1999-01-01

    One of the most severe problems at any oil fields producing paraffinic oils is that of paraffin depositions. Romania which has a long experience in oil production is also faced with this problem in many oil fields. The microbial treatment, based on the activity of naturally occurring, selectively isolated bacteria, is already proved as an effective alternative to conventional methods to prevent and remove paraffin damage. Using such kind of bacterial products, exciting results for inhibiting paraffin depositions have been obtained. In this paper results concerning the naturally occurring bacteria selectively isolated from hydrocarbon polluted sites as well as from paraffinic oils, semi-solid and solid paraffin depositions are presented. After a laboratory screening, 15 bacterial strains (BS 1-15), three bacterial consortia (BC 1-3) and a Special Bacterial Consortium (SBC1) were selected. For the selection of bacterial consortia, the classical enrichment culture method has been used. The Special Bacterial Consortium resulted from a mixture of BS 1-15 and BC 1-3 following the steps of the classical enrichment culture method. The BS 1-15, BC 1-3 and SBC1 have been tested for their performances in producing biosurfactants and biosolvents as well as for hydrocarbon utilisation. The SBC1 has been tested for its ability in degradation of hydrocarbons contained in several types of paraffinic or non-paraffinic oils, and then for inhibiting paraffin deposition on a `flow equipment` using two types of paraffinic oils. The SBC1 has been also tested for degradation of hydrocarbons contained in semi-solid and solid paraffin depositions. The results obtained could support further applications to prevent and control paraffin depositions

  14. The use of naturally occurring selectively isolated bacteria for inhibiting paraffin deposition

    International Nuclear Information System (INIS)

    Lazar, I.; Voicu, A.; Dobrota, S.; Petrisor, I.G.; Stefanescu, M.; Sandulescu, L.; Nicolescu, C.; Mucenica, D.

    1999-01-01

    One of the most severe problems at any oil fields producing paraffinic oils is that of paraffin depositions. Romania which has a long experience in oil production is also faced with this problem in many oil fields. The microbial treatment, based on the activity of naturally occurring, selectively isolated bacteria, is already proved as an effective alternative to conventional methods to prevent and remove paraffin damage. Using such kind of bacterial products, exciting results for inhibiting paraffin depositions have been obtained. In this paper results concerning the naturally occurring bacteria selectively isolated from hydrocarbon polluted sites as well as from paraffinic oils, semi-solid and solid paraffin depositions are presented. After a laboratory screening, 15 bacterial strains (BS 1-15), three bacterial consortia (BC 1-3) and a Special Bacterial Consortium (SBC1) were selected. For the selection of bacterial consortia, the classical enrichment culture method has been used. The Special Bacterial Consortium resulted from a mixture of BS 1-15 and BC 1-3 following the steps of the classical enrichment culture method. The BS 1-15, BC 1-3 and SBC1 have been tested for their performances in producing biosurfactants and biosolvents as well as for hydrocarbon utilisation. The SBC1 has been tested for its ability in degradation of hydrocarbons contained in several types of paraffinic or non-paraffinic oils, and then for inhibiting paraffin deposition on a 'flow equipment' using two types of paraffinic oils. The SBC1 has been also tested for degradation of hydrocarbons contained in semi-solid and solid paraffin depositions. The results obtained could support further applications to prevent and control paraffin depositions

  15. Induced defences alter the strength and direction of natural selection on reproductive traits in common milkweed.

    Science.gov (United States)

    Thompson, K A; Cory, K A; Johnson, M T J

    2017-06-01

    Evolutionary biologists have long sought to understand the ecological processes that generate plant reproductive diversity. Recent evidence indicates that constitutive antiherbivore defences can alter natural selection on reproductive traits, but it is unclear whether induced defences will have the same effect and whether reduced foliar damage in defended plants is the cause of this pattern. In a factorial field experiment using common milkweed, Asclepias syriaca L., we induced plant defences using jasmonic acid (JA) and imposed foliar damage using scissors. We found that JA-induced plants experienced selection for more inflorescences that were smaller in size (fewer flowers), whereas control plants only experienced a trend towards selection for larger inflorescences (more flowers); all effects were independent of foliar damage. Our results demonstrate that induced defences can alter both the strength and direction of selection on reproductive traits, and suggest that antiherbivore defences may promote the evolution of plant reproductive diversity. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

  16. Selecting the Number of Principal Components in Functional Data

    KAUST Repository

    Li, Yehua; Wang, Naisyin; Carroll, Raymond J.

    2013-01-01

    functional data also perform well for sparse functional data. An empirical example using colon carcinogenesis data is also provided to illustrate the results. Supplementary materials for this article are available online. © 2013 American Statistical

  17. The spectra of selected functional gastrointestinal disorders in ...

    African Journals Online (AJOL)

    Background: The prevalence of functional gastrointestinal disorders (FGIDs) including functional dyspepsia (FD), irritable bowel syndrome (IBS) and functional constipation (FC) was not studied in Sudan. Objectives: The aim of this study is to estimate prevalence of these disorders in Sudanese university students using ...

  18. Evaluation of selected parameters of rat liver and kidney function ...

    African Journals Online (AJOL)

    Dr. J. T. Ekanem

    grouped into two such that one group was orally administered with 14mg/kg body weight on daily basis for 15days ... The complex nature of human sexual response and penile physiology .... measured by the dye excretion tests, clearance.

  19. Natural Selection on Genes Related to Cardiovascular Health in High-Altitude Adapted Andeans.

    Science.gov (United States)

    Crawford, Jacob E; Amaru, Ricardo; Song, Jihyun; Julian, Colleen G; Racimo, Fernando; Cheng, Jade Yu; Guo, Xiuqing; Yao, Jie; Ambale-Venkatesh, Bharath; Lima, João A; Rotter, Jerome I; Stehlik, Josef; Moore, Lorna G; Prchal, Josef T; Nielsen, Rasmus

    2017-11-02

    The increase in red blood cell mass (polycythemia) due to the reduced oxygen availability (hypoxia) of residence at high altitude or other conditions is generally thought to be beneficial in terms of increasing tissue oxygen supply. However, the extreme polycythemia and accompanying increased mortality due to heart failure in chronic mountain sickness most likely reduces fitness. Tibetan highlanders have adapted to high altitude, possibly in part via the selection of genetic variants associated with reduced polycythemic response to hypoxia. In contrast, high-altitude-adapted Quechua- and Aymara-speaking inhabitants of the Andean Altiplano are not protected from high-altitude polycythemia in the same way, yet they exhibit other adaptive features for which the genetic underpinnings remain obscure. Here, we used whole-genome sequencing to scan high-altitude Andeans for signals of selection. The genes showing the strongest evidence of selection-including BRINP3, NOS2, and TBX5-are associated with cardiovascular development and function but are not in the response-to-hypoxia pathway. Using association mapping, we demonstrated that the haplotypes under selection are associated with phenotypic variations related to cardiovascular health. We hypothesize that selection in response to hypoxia in Andeans could have vascular effects and could serve to mitigate the deleterious effects of polycythemia rather than reduce polycythemia itself. Copyright © 2017. Published by Elsevier Inc.

  20. Signatures of natural selection between life cycle stages separated by metamorphosis in European eel.

    Science.gov (United States)

    Pujolar, J M; Jacobsen, M W; Bekkevold, D; Lobón-Cervià, J; Jónsson, B; Bernatchez, L; Hansen, M M

    2015-08-13

    Species showing complex life cycles provide excellent opportunities to study the genetic associations between life cycle stages, as selective pressures may differ before and after metamorphosis. The European eel presents a complex life cycle with two metamorphoses, a first metamorphosis from larvae into glass eels (juvenile stage) and a second metamorphosis into silver eels (adult stage). We tested the hypothesis that different genes and gene pathways will be under selection at different life stages when comparing the genetic associations between glass eels and silver eels. We used two sets of markers to test for selection: first, we genotyped individuals using a panel of 80 coding-gene single nucleotide polymorphisms (SNPs) developed in American eel; second, we investigated selection at the genome level using a total of 153,423 RAD-sequencing generated SNPs widely distributed across the genome. Using the RAD approach, outlier tests identified a total of 2413 (1.57%) potentially selected SNPs. Functional annotation analysis identified signal transduction pathways as the most over-represented group of genes, including MAPK/Erk signalling, calcium signalling and GnRH (gonadotropin-releasing hormone) signalling. Many of the over-represented pathways were related to growth, while others could result from the different conditions that eels inhabit during their life cycle. The observation of different genes and gene pathways under selection when comparing glass eels vs. silver eels supports the adaptive decoupling hypothesis for the benefits of metamorphosis. Partitioning the life cycle into discrete morphological phases may be overall beneficial since it allows the different life stages to respond independently to their unique selection pressures. This might translate into a more effective use of food and niche resources and/or performance of phase-specific tasks (e.g. feeding in the case of glass eels, migrating and reproducing in the case of silver eels).

  1. Positive selection in octopus haemocyanin indicates functional links to temperature adaptation.

    Science.gov (United States)

    Oellermann, Michael; Strugnell, Jan M; Lieb, Bernhard; Mark, Felix C

    2015-07-05

    Octopods have successfully colonised the world's oceans from the tropics to the poles. Yet, successful persistence in these habitats has required adaptations of their advanced physiological apparatus to compensate impaired oxygen supply. Their oxygen transporter haemocyanin plays a major role in cold tolerance and accordingly has undergone functional modifications to sustain oxygen release at sub-zero temperatures. However, it remains unknown how molecular properties evolved to explain the observed functional adaptations. We thus aimed to assess whether natural selection affected molecular and structural properties of haemocyanin that explains temperature adaptation in octopods. Analysis of 239 partial sequences of the haemocyanin functional units (FU) f and g of 28 octopod species of polar, temperate, subtropical and tropical origin revealed natural selection was acting primarily on charge properties of surface residues. Polar octopods contained haemocyanins with higher net surface charge due to decreased glutamic acid content and higher numbers of basic amino acids. Within the analysed partial sequences, positive selection was present at site 2545, positioned between the active copper binding centre and the FU g surface. At this site, methionine was the dominant amino acid in polar octopods and leucine was dominant in tropical octopods. Sites directly involved in oxygen binding or quaternary interactions were highly conserved within the analysed sequence. This study has provided the first insight into molecular and structural mechanisms that have enabled octopods to sustain oxygen supply from polar to tropical conditions. Our findings imply modulation of oxygen binding via charge-charge interaction at the protein surface, which stabilize quaternary interactions among functional units to reduce detrimental effects of high pH on venous oxygen release. Of the observed partial haemocyanin sequence, residue 2545 formed a close link between the FU g surface and the

  2. Lack of direct evidence for natural selection at the candidate thrifty gene locus, PPARGC1A.

    Science.gov (United States)

    Cadzow, Murray; Merriman, Tony R; Boocock, James; Dalbeth, Nicola; Stamp, Lisa K; Black, Michael A; Visscher, Peter M; Wilcox, Phillip L

    2016-11-15

    The gene PPARGC1A, in particular the Gly482Ser variant (rs8192678), had been proposed to be subject to natural selection, particularly in recent progenitors of extant Polynesian populations. Reasons include high levels of population differentiation and increased frequencies of the derived type 2 diabetes (T2D) risk 482Ser allele, and association with body mass index (BMI) in a small Tongan population. However, no direct statistical tests for selection have been applied. Using a range of Polynesian populations (Tongan, Māori, Samoan) we re-examined evidence for association between Gly482Ser with T2D and BMI as well as gout. Using also Asian, European, and African 1000 Genome Project samples a range of statistical tests for selection (F ST , integrated haplotype score (iHS), cross population extended haplotype homozygosity (XP-EHH), Tajima's D and Fay and Wu's H) were conducted on the PPARGC1A locus. No statistically significant evidence for association between Gly482Ser and any of BMI, T2D or gout was found. Population differentiation (F ST ) was smallest between Asian and Pacific populations (New Zealand Māori ≤ 0.35, Samoan ≤ 0.20). When compared to European (New Zealand Māori ≤ 0.40, Samoan ≤ 0.25) or African populations (New Zealand Māori ≤ 0.80, Samoan ≤ 0.66) this differentiation was larger. We did not find any strong evidence for departure from neutral evolution at this locus when applying any of the other statistical tests for selection. However, using the same analytical methods, we found evidence for selection in specific populations at previously identified loci, indicating that lack of selection was the most likely explanation for the lack of evidence of selection in PPARGC1A. We conclude that there is no compelling evidence for selection at this locus, and that this gene should not be considered a candidate thrifty gene locus in Pacific populations. High levels of population differentiation at this locus and the

  3. Ancestry variation and footprints of natural selection along the genome in Latin American populations.

    Science.gov (United States)

    Deng, Lian; Ruiz-Linares, Andrés; Xu, Shuhua; Wang, Sijia

    2016-02-18

    Latin American populations stem from the admixture of Europeans, Africans and Native Americans, which started over 400 years ago and had lasted for several centuries. Extreme deviation over the genome-wide average in ancestry estimations at certain genomic locations could reflect recent natural selection. We evaluated the distribution of ancestry estimations using 678 genome-wide microsatellite markers in 249 individuals from 13 admixed populations across Latin America. We found significant deviations in ancestry estimations including three locations with more than 3.5 times standard deviations from the genome-wide average: an excess of European ancestry at 1p36 and 14q32, and an excess of African ancestry at 6p22. Using simulations, we could show that at least the deviation at 6p22 was unlikely to result from genetic drift alone. By applying different linguistic groups as well as the most likely ancestral Native American populations as the ancestry, we showed that the choice of Native American ancestry could affect the local ancestry estimation. However, the signal at 6p22 consistently appeared in most of the analyses using various ancestral groups. This study provided important insights for recent natural selection in the context of the unique history of the New World and implications for disease mapping.

  4. Complementary effect of natural and sexual selection against immigrants maintains differentiation between locally adapted fish

    Science.gov (United States)

    Plath, Martin; Riesch, Rüdiger; Oranth, Alexandra; Dzienko, Justina; Karau, Nora; Schießl, Angela; Stadler, Stefan; Wigh, Adriana; Zimmer, Claudia; Arias-Rodriguez, Lenin; Schlupp, Ingo; Tobler, Michael

    2010-08-01

    Adaptation to ecologically heterogeneous environments can drive speciation. But what mechanisms maintain reproductive isolation among locally adapted populations? Using poeciliid fishes in a system with naturally occurring toxic hydrogen sulfide, we show that (a) fish from non-sulfidic sites ( Poecilia mexicana) show high mortality (95 %) after 24 h when exposed to the toxicant, while locally adapted fish from sulfidic sites ( Poecilia sulphuraria) experience low mortality (13 %) when transferred to non-sulfidic water. (b) Mate choice tests revealed that P. mexicana females exhibit a preference for conspecific males in non-sulfidic water, but not in sulfidic water, whereas P. sulphuraria females never showed a preference. Increased costs of mate choice in sulfidic, hypoxic water, and the lack of selection for reinforcement due to the low survival of P. mexicana may explain the absence of a preference in P. sulphuraria females. Taken together, our study may be the first to demonstrate independent—but complementary—effects of natural and sexual selection against immigrants maintaining differentiation between locally adapted fish populations.

  5. The magnitude and selectivity of natural and multiple anthropogenic mortality causes in hunted brown bears.

    Science.gov (United States)

    Bischof, Richard; Swenson, Jon E; Yoccoz, Nigel G; Mysterud, Atle; Gimenez, Olivier

    2009-05-01

    1. The population dynamic and evolutionary effects of harvesting are receiving growing attention among biologists. Cause-specific estimates of mortality are necessary to determine and compare the magnitude and selectivity of hunting and other types of mortalities. In addition to the logistic and financial constraints on longitudinal studies, they are complicated by the fact that nonhunting mortality in managed populations usually consists of a mix of natural and human-caused factors. 2. We used multistate capture-recapture (MCR) models to estimate cause-specific survival of brown bears (Ursus arctos) in two subpopulations in Sweden over a 23-year period. In our analysis, we distinguished between legal hunting and other sources of mortality, such as intraspecific predation, accidents, poaching, and damage control removals. We also tested whether a strong increase in harvest quotas after 1997 in one of the subpopulations affected vulnerability to legal hunting. 3. Although only a fraction of mortalities other than legal hunting could be considered natural, this group of causes showed a general pattern of demographic selectivity expected from natural mortality regimes in populations of long-lived species, namely greater vulnerability of young animals. On the other hand, demographic effects on hunting vulnerability were weak and inconsistent. Our findings support the assumption that hunting and other mortalities were additive. 4. As expected, an increase in hunting pressure coincided with a correspondingly large increase in vulnerability to hunting in the affected subpopulation. Because even unbiased harvest can lead to selective pressures on life-history traits, such as size at primiparity, increasing harvest quotas may not only affect population growth directly, but could also alter optimal life-history strategies in brown bears and other carnivores. 5. Legal hunting is the most conveniently assessed and the most easily managed cause of mortality in many wild

  6. Charles Darwin, Richard Owen, and Natural Selection: A Question of Priority.

    Science.gov (United States)

    Johnson, Curtis N

    2018-05-03

    No single author presented Darwin with a more difficult question about his priority in discovering natural selection than the British comparative anatomist and paleontologist Richard Owen. Owen was arguably the most influential biologist in Great Britain in Darwin's time. Darwin wanted his approbation for what he believed to be his own theory of natural selection. Unfortunately for Darwin, when Owen first commented in publication about Darwin's theory of descent he was openly hostile (Edinb. Rev. vol. 111, Article VIII, 1860, pp. 487-533, anonymous). Darwin was taken off-guard. In private meetings and correspondence prior to 1860 Owen had been nothing but polite and friendly, even helping Darwin in cataloguing and analyzing Darwin's zoological specimens from the Beagle voyage. Every early indication predicted a life-long friendship and collaboration. But that was not to be. Owen followed his slashing review with a mounting campaign in the 1860s to denounce and discredit both Darwin and his small but ascendant circle of friends and supporters. But that was not enough for Owen. Starting in 1866, perhaps by now realizing Darwin had landed the big fish, Owen launched a new campaign, to claim the discovery of "Darwin's theory" for himself. Darwin naturally fought back, mainly in the "Historical Sketch" that he prefaced to Origin starting in 1861. But when we peel back the layers of personal animus and escalating vituperation we discover in fact their quarrel was generated more by mutual misunderstanding than scientific disagreement. The battle ended only when Darwin finally penetrated to the crux of the matter and put an end to the rivalry in 1872, in the final version of the Sketch.

  7. David Hull's generalized natural selection as an explanation for scientific change

    Science.gov (United States)

    Little, Michelle Yvette

    2001-10-01

    Philosophers of science such as Karl Popper and Thomas Kuhn have employed evolutionary idiom in describing scientific change. In Science as a Process (1988) Hull makes evolutionary theory explanatorily applicable. He modifies key evolutionary terms in order that both biological evolution and scientific change are instances of a general selection process. According to Hull, because of naturally-existing competition for credit among researchers and the professional lineages they constitute, scientists are constrained to cooperate and collaborate. This process entails two important philosophical consequences. First, it allows for a natural justification of why the sciences can provide objective empirical knowledge. Second, appreciating its strength means that a philosophical analysis of scientific change is solidly difficult features to combine. I work on strengthening two weaknesses in Hull's arguments. First, operating in his analysis is an unexplicated notion of ``information'' running parallel to the equally opaque notion of genetic information. My third chapter provides a clear account of ``genetic information'' whose usefulness extends beyond the assistance it can render Hull as a clear concept is needed in biological contexts as well. The fourth and fifth chapters submit evidence of scientific change from radio astronomy. Hull insists on empirical backing for philosophical theses but his own book stands to suffer from selection effects as it offers cases drawn from a single subspecialty in the biological sciences. I found that in the main scientists and the change they propel accords well with Hull's explanation. However, instances of major change reveal credit- and resource-sharing to a degree contrary with what Hull would expect. My conclusion is that the naturalness of competition, instantiated during the course of standardized and relatively ``normal'' scientific research, is not the norm during periods of new research and its uncertain standards of

  8. Nature and regulation of the insulin receptor: structure and function

    International Nuclear Information System (INIS)

    Czech, M.P.

    1985-01-01

    Native, cell-surface insulin receptor consists of two glycoprotein subunit types with apparent masses of about 125,000 daltons (alpha subunit) and 90,000 daltons (beta subunit). The alpha and beta insulin-receptor subunits seem to have distinct functions such that alpha appears to bind hormone whereas beta appears to possess intrinsic tyrosine kinase activity. In detergent extracts, insulin activates receptor autophosphorylation of tyrosine residues on its beta subunit, whereas in the presence of reductant, the alpha subunit is also phosphorylated. In intact cells, insulin activates serine/threonine phosphorylation of insulin receptor beta subunit as well as tyrosine phosphorylation. The biological role of the receptor-associated tyrosine kinase is not known. The insulin receptor kinase is regulated by beta-adrenergic agonists and other agents that elevate cAMP in adipocytes, presumably via the cAMP-dependent protein kinase. Such agents decrease receptor affinity for insulin and partially uncouple receptor tyrosine kinase activity from activation by insulin. These effects appear to contribute to the biological antagonism between insulin and beta-agonists. These data suggest the hypothesis that a complex network of tyrosine and serine/threonine phosphorylations on the insulin receptor modulate its binding and kinase activities in an antagonistic manner

  9. Detecting Genomic Signatures of Natural Selection with Principal Component Analysis: Application to the 1000 Genomes Data.

    Science.gov (United States)

    Duforet-Frebourg, Nicolas; Luu, Keurcien; Laval, Guillaume; Bazin, Eric; Blum, Michael G B

    2016-04-01

    To characterize natural selection, various analytical methods for detecting candidate genomic regions have been developed. We propose to perform genome-wide scans of natural selection using principal component analysis (PCA). We show that the common FST index of genetic differentiation between populations can be viewed as the proportion of variance explained by the principal components. Considering the correlations between genetic variants and each principal component provides a conceptual framework to detect genetic variants involved in local adaptation without any prior definition of populations. To validate the PCA-based approach, we consider the 1000 Genomes data (phase 1) considering 850 individuals coming from Africa, Asia, and Europe. The number of genetic variants is of the order of 36 millions obtained with a low-coverage sequencing depth (3×). The correlations between genetic variation and each principal component provide well-known targets for positive selection (EDAR, SLC24A5, SLC45A2, DARC), and also new candidate genes (APPBPP2, TP1A1, RTTN, KCNMA, MYO5C) and noncoding RNAs. In addition to identifying genes involved in biological adaptation, we identify two biological pathways involved in polygenic adaptation that are related to the innate immune system (beta defensins) and to lipid metabolism (fatty acid omega oxidation). An additional analysis of European data shows that a genome scan based on PCA retrieves classical examples of local adaptation even when there are no well-defined populations. PCA-based statistics, implemented in the PCAdapt R package and the PCAdapt fast open-source software, retrieve well-known signals of human adaptation, which is encouraging for future whole-genome sequencing project, especially when defining populations is difficult. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  10. Natural selection maintains a single-locus leaf shape cline in Ivyleaf morning glory, Ipomoea hederacea.

    Science.gov (United States)

    Campitelli, Brandon E; Stinchcombe, John R

    2013-02-01

    Clines in phenotypic traits with an underlying genetic basis potentially implicate natural selection. However, neutral evolutionary processes such as random colonization, spatially restricted gene flow, and genetic drift could also result in similar spatial patterns, especially for single-locus traits because of their susceptibility to stochastic events. One way to distinguish between adaptive and neutral mechanisms is to compare the focal trait to neutral genetic loci to determine whether neutral loci demonstrate clinal variation (consistent with a neutral cline), or not. Ivyleaf morning glory, Ipomoea hederacea, exhibits a latitudinal cline for a Mendelian leaf shape polymorphism in eastern North America, such that lobed genotypes dominate northern populations and heart-shaped genotypes are restricted to southern populations. Here, we evaluate potential evolutionary mechanisms for this cline by first determining the allele frequencies at the leaf shape locus for 77 populations distributed throughout I. hederacea's range and then comparing the geographical pattern at this locus to neutral amplified fragment length polymorphism (AFLP) loci. We detected both significant clinal variation and high genetic differentiation at the leaf shape locus across all populations. In contrast, 99% of the putatively neutral loci do not display clinal variation, and I. hederacea populations show very little overall genetic differentiation, suggesting that there is a moderate level of gene flow. In addition, the leaf shape locus was identified as a major F(ST) outlier experiencing divergent selection, relative to all the AFLP loci. Together, these data strongly suggest that the cline in leaf shape is being maintained by spatially varying natural selection. © 2012 Blackwell Publishing Ltd.

  11. Fluorination of Naturally Occurring N6-Benzyladenosine Remarkably Increased Its Antiviral Activity and Selectivity

    Directory of Open Access Journals (Sweden)

    Vladimir E. Oslovsky

    2017-07-01

    Full Text Available Recently, we demonstrated that the natural cytokinin nucleosides N6-isopentenyladenosine (iPR and N6-benzyladenosine (BAPR exert a potent and selective antiviral effect on the replication of human enterovirus 71. In order to further characterize the antiviral profile of this class of compounds, we generated a series of fluorinated derivatives of BAPR and evaluated their activity on the replication of human enterovirus 71 in a cytopathic effect (CPE reduction assay. The monofluorination of the BAPR-phenyl group changed the selectivity index (SI slightly because of the concomitant high cell toxicity. Interestingly, the incorporation of a second fluorine atom resulted in a dramatic improvement of selectivity. Moreover, N6-trifluoromethylbenzyladenosine derivatives (9–11 exhibited also a very interesting profile, with low cytotoxicity observed. In particular, the analogue N6-(3-trifluoromethylbenzyl-adenosine (10 with a four-fold gain in potency as compared to BAPR and the best SI in the class represents a promising candidate for further development.

  12. Artificial selection for structural color on butterfly wings and comparison with natural evolution.

    Science.gov (United States)

    Wasik, Bethany R; Liew, Seng Fatt; Lilien, David A; Dinwiddie, April J; Noh, Heeso; Cao, Hui; Monteiro, Antónia

    2014-08-19

    Brilliant animal colors often are produced from light interacting with intricate nano-morphologies present in biological materials such as butterfly wing scales. Surveys across widely divergent butterfly species have identified multiple mechanisms of structural color production; however, little is known about how these colors evolved. Here, we examine how closely related species and populations of Bicyclus butterflies have evolved violet structural color from brown-pigmented ancestors with UV structural color. We used artificial selection on a laboratory model butterfly, B. anynana, to evolve violet scales from UV brown scales and compared the mechanism of violet color production with that of two other Bicyclus species, Bicyclus sambulos and Bicyclus medontias, which have evolved violet/blue scales independently via natural selection. The UV reflectance peak of B. anynana brown scales shifted to violet over six generations of artificial selection (i.e., in less than 1 y) as the result of an increase in the thickness of the lower lamina in ground scales. Similar scale structures and the same mechanism for producing violet/blue structural colors were found in the other Bicyclus species. This work shows that populations harbor large amounts of standing genetic variation that can lead to rapid evolution of scales' structural color via slight modifications to the scales' physical dimensions.

  13. Bandwidth selection in smoothing functions | Kibua | East African ...

    African Journals Online (AJOL)

    ... inexpensive and, hence, worth adopting. We argue that the bandwidth parameter is determined by two factors: the kernel function and the length of the smoothing region. We give an illustrative example of its application using real data. Keywords: Kernel, Smoothing functions, Bandwidth > East African Journal of Statistics ...

  14. The neuropsychology of face perception: beyond simple dissociations and functional selectivity.

    Science.gov (United States)

    Atkinson, Anthony P; Adolphs, Ralph

    2011-06-12

    Face processing relies on a distributed, patchy network of cortical regions in the temporal and frontal lobes that respond disproportionately to face stimuli, other cortical regions that are not even primarily visual (such as somatosensory cortex), and subcortical structures such as the amygdala. Higher-level face perception abilities, such as judging identity, emotion and trustworthiness, appear to rely on an intact face-processing network that includes the occipital face area (OFA), whereas lower-level face categorization abilities, such as discriminating faces from objects, can be achieved without OFA, perhaps via the direct connections to the fusiform face area (FFA) from several extrastriate cortical areas. Some lesion, transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) findings argue against a strict feed-forward hierarchical model of face perception, in which the OFA is the principal and common source of input for other visual and non-visual cortical regions involved in face perception, including the FFA, face-selective superior temporal sulcus and somatosensory cortex. Instead, these findings point to a more interactive model in which higher-level face perception abilities depend on the interplay between several functionally and anatomically distinct neural regions. Furthermore, the nature of these interactions may depend on the particular demands of the task. We review the lesion and TMS literature on this topic and highlight the dynamic and distributed nature of face processing.

  15. Enhancing Web Service Selection by User Preferences of Non-Functional Features

    OpenAIRE

    Badr , Youakim; Abraham , Ajith; Biennier , Frédérique; Grosan , Crina

    2008-01-01

    International audience; Selection of an appropriate Web service for a particular task has become a difficult challenge due to the increasing number of Web services offering similar functionalities. The functional properties describe what the service can do and the nonfunctional properties depict how the service can do it. Non-functional properties involving qualitative or quantitative features have become essential criteria to enhance the selection process of services making the selection pro...

  16. Frequency Selective Surfaces for extended Bandwidth backing reflector functions

    NARCIS (Netherlands)

    Pasian, M.; Neto, A.; Monni, S.; Ettorre, M.; Gerini, G.

    2008-01-01

    This paper deals with the use of Frequency Selective Surfaces (FSS) to increase the Efficiency × Bandwidth product in Ultra-Wide Band (UWB) antenna arrays whose efficiency is limited by the front-to-back ratio. If the backing reflector is realized in one metal plane solution its location will be

  17. Selective functionalization of cavitands: synthesis of a new hemicarcerand

    NARCIS (Netherlands)

    Timmerman, P.; van Mook, Maarten G.A.; Verboom, Willem; van Hummel, G.J.; Harkema, Sybolt; Reinhoudt, David

    1992-01-01

    Partly bridged cavitands 2 and 4 can be selectively debrominated in one step by treatment with 5 equiv of n-BuLi in THF to afford the corresponding dibromo derivatives 5 and 6 in 90% and 77% yield, respectively. After incorporatin of the fourth bridge, the remaining two bromines can be replaced by

  18. Lifetime information from correlation functions selected by directional cuts

    International Nuclear Information System (INIS)

    Gelbke, C.K.

    1995-01-01

    Two-particle correlation functions provide information on the space-time characteristics of the emitting source. In many cases, ambiguities of the relative magnitudes of source radius and lifetime can be reduced by analysis of correlation functions evaluated for specific directional cuts on the relative velocity of the coincident particle pair. Information on non-spherical breakup geometries is more difficult to extract. Examples of two-proton correlation functions in which directional cuts are employed to reduce existing space-time ambiguities for the emitting system are presented. (author). 50 refs., 10 figs

  19. Affective Neuronal Selection:The Nature of the Primordial Emotion Systems

    Directory of Open Access Journals (Sweden)

    George F R Ellis

    2013-01-01

    Full Text Available Based on studies in affective neuroscience and evolutionary psychiatry, a tentative new proposal is made here as to the nature and identification of primordial emotional systems. Our model stresses phylogenetic origins of emotional systems, which we believe is necessary for a full understanding of the functions of emotions and additionally suggests that emotional organising systems play a role in sculpting the brain during ontogeny. Nascent emotional systems thus affect cognitive development. A second proposal concerns two additions to the affective systems identified by Panksepp. We suggest there is substantial evidence for a primary emotional organising programme dealing with power, rank, dominance and subordination which instantiates competitive and territorial behaviour and is an evolutionary contributor to self-esteem in humans. A programme underlying disgust reactions which originally functioned in ancient vertebrates to protect against infection and toxins is also suggested.

  20. Landscape genomics: natural selection drives the evolution of mitogenome in penguins.

    Science.gov (United States)

    Ramos, Barbara; González-Acuña, Daniel; Loyola, David E; Johnson, Warren E; Parker, Patricia G; Massaro, Melanie; Dantas, Gisele P M; Miranda, Marcelo D; Vianna, Juliana A

    2018-01-16

    Mitochondria play a key role in the balance of energy and heat production, and therefore the mitochondrial genome is under natural selection by environmental temperature and food availability, since starvation can generate more efficient coupling of energy production. However, selection over mitochondrial DNA (mtDNA) genes has usually been evaluated at the population level. We sequenced by NGS 12 mitogenomes and with four published genomes, assessed genetic variation in ten penguin species distributed from the equator to Antarctica. Signatures of selection of 13 mitochondrial protein-coding genes were evaluated by comparing among species within and among genera (Spheniscus, Pygoscelis, Eudyptula, Eudyptes and Aptenodytes). The genetic data were correlated with environmental data obtained through remote sensing (sea surface temperature [SST], chlorophyll levels [Chl] and a combination of SST and Chl [COM]) through the distribution of these species. We identified the complete mtDNA genomes of several penguin species, including ND6 and 8 tRNAs on the light strand and 12 protein coding genes, 14 tRNAs and two rRNAs positioned on the heavy strand. The highest diversity was found in NADH dehydrogenase genes and the lowest in COX genes. The lowest evolutionary divergence among species was between Humboldt (Spheniscus humboldti) and Galapagos (S. mendiculus) penguins (0.004), while the highest was observed between little penguin (Eudyptula minor) and Adélie penguin (Pygoscelis adeliae) (0.097). We identified a signature of purifying selection (Ka/Ks penguins. In contrast, COX1 had a signature of strong negative selection. ND4 Ka/Ks ratios were highly correlated with SST (Mantel, p-value: 0.0001; GLM, p-value: 0.00001) and thus may be related to climate adaptation throughout penguin speciation. These results identify mtDNA candidate genes under selection which could be involved in broad-scale adaptations of penguins to their environment. Such knowledge may be

  1. Bacteria Associated to Plants Naturally Selected in a Historical PCB Polluted Soil Show Potential to Sustain Natural Attenuation

    KAUST Repository

    Vergani, Lorenzo; Mapelli, Francesca; Marasco, Ramona; Crotti, Elena; Fusi, Marco; Di Guardo, Antonio; Armiraglio, Stefano; Daffonchio, Daniele; Borin, Sara

    2017-01-01

    The exploitation of the association between plants and microorganisms is a promising approach able to boost natural attenuation processes for soil clean-up in vast polluted areas characterized by mixed chemical contamination. We aimed to explore

  2. Random genetic drift, natural selection, and noise in human cranial evolution.

    Science.gov (United States)

    Roseman, Charles C

    2016-08-01

    This study assesses the extent to which relationships among groups complicate comparative studies of adaptation in recent human cranial variation and the extent to which departures from neutral additive models of evolution hinder the reconstruction of population relationships among groups using cranial morphology. Using a maximum likelihood evolutionary model fitting approach and a mixed population genomic and cranial data set, I evaluate the relative fits of several widely used models of human cranial evolution. Moreover, I compare the goodness of fit of models of cranial evolution constrained by genomic variation to test hypotheses about population specific departures from neutrality. Models from population genomics are much better fits to cranial variation than are traditional models from comparative human biology. There is not enough evolutionary information in the cranium to reconstruct much of recent human evolution but the influence of population history on cranial variation is strong enough to cause comparative studies of adaptation serious difficulties. Deviations from a model of random genetic drift along a tree-like population history show the importance of environmental effects, gene flow, and/or natural selection on human cranial variation. Moreover, there is a strong signal of the effect of natural selection or an environmental factor on a group of humans from Siberia. The evolution of the human cranium is complex and no one evolutionary process has prevailed at the expense of all others. A holistic unification of phenome, genome, and environmental context, gives us a strong point of purchase on these problems, which is unavailable to any one traditional approach alone. Am J Phys Anthropol 160:582-592, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  3. Selective whole genome amplification for resequencing target microbial species from complex natural samples.

    Science.gov (United States)

    Leichty, Aaron R; Brisson, Dustin

    2014-10-01

    Population genomic analyses have demonstrated power to address major questions in evolutionary and molecular microbiology. Collecting populations of genomes is hindered in many microbial species by the absence of a cost effective and practical method to collect ample quantities of sufficiently pure genomic DNA for next-generation sequencing. Here we present a simple method to amplify genomes of a target microbial species present in a complex, natural sample. The selective whole genome amplification (SWGA) technique amplifies target genomes using nucleotide sequence motifs that are common in the target microbe genome, but rare in the background genomes, to prime the highly processive phi29 polymerase. SWGA thus selectively amplifies the target genome from samples in which it originally represented a minor fraction of the total DNA. The post-SWGA samples are enriched in target genomic DNA, which are ideal for population resequencing. We demonstrate the efficacy of SWGA using both laboratory-prepared mixtures of cultured microbes as well as a natural host-microbe association. Targeted amplification of Borrelia burgdorferi mixed with Escherichia coli at genome ratios of 1:2000 resulted in >10(5)-fold amplification of the target genomes with genomic extracts from Wolbachia pipientis-infected Drosophila melanogaster resulted in up to 70% of high-throughput resequencing reads mapping to the W. pipientis genome. By contrast, 2-9% of sequencing reads were derived from W. pipientis without prior amplification. The SWGA technique results in high sequencing coverage at a fraction of the sequencing effort, thus allowing population genomic studies at affordable costs. Copyright © 2014 by the Genetics Society of America.

  4. Selection of Alternatives for the Natural Gas Supply in Colombia using the Analytic Hierarchy Process

    Directory of Open Access Journals (Sweden)

    Mauricio Becerra Fernández

    2017-05-01

    Full Text Available Context: Colombia consumes natural gas in different sectors, especially in the ones that are residential and vehicular transport. Gas consumption serves as backup for power generation in situations of reduced hydroelectric capacity. Nowadays, gas reserve levels have been reduced and it is essential to ensure the uninterrupted supply of the resource. To achieve such objective, there are some alternatives which are difficult to implement at the same time, given the limited financial budget and implementation times that they demanded. In this way, several studies have advanced in the application of models to prioritize alternatives for both supplying power and reducing emissions in the generation, especially regarding the evaluation of energy sources and technology selection for supply. Method: The Analytic Hierarchy Process (AHP based in the Delphi method to define preferences according to the experts judgment, was applied to evaluate the selection of alternatives supply of natural gas in Colombia, considering technical, environmental and social criteria, which is reliable and policy oriented to guarantee supply of resources in the country. Results: Once the model was applied, we evaluated the criteria and alternatives for infrastructure to support gas supply, finding that reliability is the most relevant criterion as well as alternative of building the ‘Regasification Pacific Plant’ followed by the construction of the ‘Buenaventura-Cali pipeline’ and the ‘Storage Plant in Bogotá'. Conclusions: As the results indicate, in Colombia efforts should be focus on imports of the resource through the construction of regasification plants and pipelines to facilitate transport inland to demand points. The latter may help decision makers facing various alternatives to ensure the supply of this resource, which is relevant to various economic sectors, including generation of electricity in the country. Language: Spanish

  5. THE zCOSMOS-SINFONI PROJECT. I. SAMPLE SELECTION AND NATURAL-SEEING OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Mancini, C.; Renzini, A. [INAF-OAPD, Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, I-35122 Padova (Italy); Foerster Schreiber, N. M.; Hicks, E. K. S.; Genzel, R.; Tacconi, L.; Davies, R. [Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany); Cresci, G. [Osservatorio Astrofisico di Arcetri (OAF), INAF-Firenze, Largo E. Fermi 5, I-50125 Firenze (Italy); Peng, Y.; Lilly, S.; Carollo, M.; Oesch, P. [Institute of Astronomy, Department of Physics, Eidgenossische Technische Hochschule, ETH Zurich CH-8093 (Switzerland); Vergani, D.; Pozzetti, L.; Zamorani, G. [INAF-Bologna, Via Ranzani, I-40127 Bologna (Italy); Daddi, E. [CEA-Saclay, DSM/DAPNIA/Service d' Astrophysique, F-91191 Gif-Sur Yvette Cedex (France); Maraston, C. [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, PO1 3HE Portsmouth (United Kingdom); McCracken, H. J. [IAP, 98bis bd Arago, F-75014 Paris (France); Bouche, N. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Shapiro, K. [Aerospace Research Laboratories, Northrop Grumman Aerospace Systems, Redondo Beach, CA 90278 (United States); and others

    2011-12-10

    The zCOSMOS-SINFONI project is aimed at studying the physical and kinematical properties of a sample of massive z {approx} 1.4-2.5 star-forming galaxies, through SINFONI near-infrared integral field spectroscopy (IFS), combined with the multiwavelength information from the zCOSMOS (COSMOS) survey. The project is based on one hour of natural-seeing observations per target, and adaptive optics (AO) follow-up for a major part of the sample, which includes 30 galaxies selected from the zCOSMOS/VIMOS spectroscopic survey. This first paper presents the sample selection, and the global physical characterization of the target galaxies from multicolor photometry, i.e., star formation rate (SFR), stellar mass, age, etc. The H{alpha} integrated properties, such as, flux, velocity dispersion, and size, are derived from the natural-seeing observations, while the follow-up AO observations will be presented in the next paper of this series. Our sample appears to be well representative of star-forming galaxies at z {approx} 2, covering a wide range in mass and SFR. The H{alpha} integrated properties of the 25 H{alpha} detected galaxies are similar to those of other IFS samples at the same redshifts. Good agreement is found among the SFRs derived from H{alpha} luminosity and other diagnostic methods, provided the extinction affecting the H{alpha} luminosity is about twice that affecting the continuum. A preliminary kinematic analysis, based on the maximum observed velocity difference across the source and on the integrated velocity dispersion, indicates that the sample splits nearly 50-50 into rotation-dominated and velocity-dispersion-dominated galaxies, in good agreement with previous surveys.

  6. Natural functions of lipopeptides from Bacillus and Pseudomonas: more than surfactants and antibiotics

    NARCIS (Netherlands)

    Raaijmakers, J.M.; Bruijn, de I.; Nybroe, O.; Ongena, M.

    2010-01-01

    Lipopeptides constitute a structurally diverse group of metabolites produced by various bacterial and fungal genera. In the past decades, research on lipopeptides has been fueled by their antimicrobial, antitumour, immunosuppressant and surfactant activities. However, the natural functions of

  7. Evolution of natural agents: preservation, advance, and emergence of functional information

    OpenAIRE

    Sharov, Alexei A.

    2016-01-01

    Biological evolution is often viewed narrowly as a change of morphology or allele frequency in a sequence of generations. Here I pursue an alternative informational concept of evolution, as preservation, advance, and emergence of functional information in natural agents. Functional information is a network of signs (e.g., memory, transient messengers, and external signs) that are used by agents to preserve and regulate their functions. Functional information is preserved in evolution via comp...

  8. Bottomland Hardwoods of the Mississippi Alluvial Valley: Characteristics and Management of Natural Function, Structure, and Composition

    Science.gov (United States)

    Paul B. Hamel; Thomas L. Foti; [Editors

    2001-01-01

    A symposium entitled "Bottomland hardwoods of the Mississippi Alluvial Valley: characteristics and management of natural function, structure, and composition" convened on October 28, 1995, as part of the Natural Areas Conference, October 25-28, 1995, In Fayetteville, AR. The symposium's goal was to provide informatibn that managers need to begin...

  9. Selection Component Analysis of Natural Polymorphisms using Population Samples Including Mother-Offspring Combinations, II

    DEFF Research Database (Denmark)

    Jarmer, Hanne Østergaard; Christiansen, Freddy Bugge

    1981-01-01

    Population samples including mother-offspring combinations provide information on the selection components: zygotic selection, sexual selection, gametic seletion and fecundity selection, on the mating pattern, and on the deviation from linkage equilibrium among the loci studied. The theory...

  10. Reduced disease in black abalone following mass mortality: Phage therapy and natural selection

    Science.gov (United States)

    VanBlaricom, Glenn R.

    2014-01-01

    Black abalone, Haliotis cracherodii, populations along the NE Pacific ocean have declined due to the rickettsial disease withering syndrome (WS). Natural recovery on San Nicolas Island (SNI) of Southern California suggested the development of resistance in island populations. Experimental challenges in one treatment demonstrated that progeny of disease-selected black abalone from SNI survived better than did those from naïve black abalone from Carmel Point in mainland coastal central California. Unexpectedly, the presence of a newly observed bacteriophage infecting the WS rickettsia (WS-RLO) had strong effects on the survival of infected abalone. Specifically, presence of phage-infected RLO (RLOv) reduced the host response to infection, RLO infection loads, and associated mortality. These data suggest that the black abalone: WS-RLO relationship is evolving through dual host mechanisms of resistance to RLO infection in the digestive gland via tolerance to infection in the primary target tissue (the post-esophagus) coupled with reduced pathogenicity of the WS-RLO by phage infection, which effectively reduces the infection load in the primary target tissue by half. Sea surface temperature patterns off southern California, associated with a recent hiatus in global-scale ocean warming, do not appear to be a sufficient explanation for survival patterns in SNI black abalone. These data highlight the potential for natural recovery of abalone populations over time and that further understanding of mechanisms governing host–parasite relationships will better enable us to manage declining populations.

  11. ON THE NATURE OF THE FIRST GALAXIES SELECTED AT 350 μm

    International Nuclear Information System (INIS)

    Khan, Sophia A.; Chanial, Pierre F.; Clements, David L.; Sumner, Timothy J.; Willner, S. P.; Ashby, M. L. N.; Fazio, G. G.; Huang, J.-S.; Pearson, Chris P.; Benford, Dominic J.; Moseley, S. Harvey; Shafer, Richard A.; Staguhn, Johannes; Dye, Simon; Farrah, Duncan; Lebouteiller, V.; Le Floc'h, Emeric; Mainetti, Gabriele; Negrello, Mattia; Serjeant, Stephen

    2009-01-01

    We present constraints on the nature of the first galaxies selected at 350 μm. The sample includes galaxies discovered in the deepest blank-field survey at 350 μm (in the Booetes Deep Field) and also later serendipitous detections in the Lockman Hole. In determining multiwavelength identifications, the 350 μm position and map resolution of the second generation Submillimeter High Angular Resolution Camera are critical, especially in the cases where multiple radio sources exist and the 24 μm counterparts are unresolved. Spectral energy distribution templates are fitted to identified counterparts, and the sample is found to comprise IR-luminous galaxies at 1 350 < 40 mJy) place these objects near the Herschel/SPIRE 350 μm confusion threshold, with the lower limit on the star formation rate density suggesting the bulk of the 350 μm contribution will come from less luminous infrared sources and normal galaxies. Therefore, the nature of the dominant source of the 350 μm background-star-forming galaxies in the epoch of peak star formation in the universe-could be more effectively probed using ground-based instruments with their angular resolution and sensitivity offering significant advantages over space-based imaging.

  12. Periodic table of virus capsids: implications for natural selection and design.

    Science.gov (United States)

    Mannige, Ranjan V; Brooks, Charles L

    2010-03-04

    For survival, most natural viruses depend upon the existence of spherical capsids: protective shells of various sizes composed of protein subunits. So far, general evolutionary pressures shaping capsid design have remained elusive, even though an understanding of such properties may help in rationally impeding the virus life cycle and designing efficient nano-assemblies. This report uncovers an unprecedented and species-independent evolutionary pressure on virus capsids, based on the the notion that the simplest capsid designs (or those capsids with the lowest "hexamer complexity", C(h)) are the fittest, which was shown to be true for all available virus capsids. The theories result in a physically meaningful periodic table of virus capsids that uncovers strong and overarching evolutionary pressures, while also offering geometric explanations to other capsid properties (rigidity, pleomorphy, auxiliary requirements, etc.) that were previously considered to be unrelatable properties of the individual virus. Apart from describing a universal rule for virus capsid evolution, our work (especially the periodic table) provides a language with which highly diverse virus capsids, unified only by geometry, may be described and related to each other. Finally, the available virus structure databases and other published data reiterate the predicted geometry-derived rules, reinforcing the role of geometry in the natural selection and design of virus capsids.

  13. Reduced disease in black abalone following mass mortality: Phage therapy and natural selection

    Directory of Open Access Journals (Sweden)

    Carolyn S Friedman

    2014-03-01

    Full Text Available Black abalone, Haliotis cracherodii, populations along the NE Pacific ocean have declined due to the rickettsial disease withering syndrome (WS. Natural recovery on San Nicolas Island (SNI off Southern California suggested the development of resistance in island populations. Experimental challenges in one treatment demonstrated that progeny of disease-selected black abalone from SNI survived better than did those from naïve black abalone from Carmel Point (CP in mainland coastal central California. Unexpectedly, the presence of a newly observed bacteriophage infecting the WS rickettsia (WS-RLO had strong effects on the survival of infected abalone. Specifically, presence of phage-infected RLO (RLOv reduced the host response to infection, RLO infection loads, and associated mortality. These data suggest that the black abalone: WS-RLO relationship is evolving through dual host mechanisms of resistance to RLO infection in the digestive gland via tolerance to infection in the primary target tissue (the post-esophagus coupled with reduced pathogenicity of the WS-RLO by phage infection, which effectively reduces the infection load in the primary target tissue by half. Sea surface temperature patterns off southern California, associated with a recent hiatus in global-scale ocean warming, do not appear to be a sufficient explanation for survival patterns in SNI black abalone. These data highlight the potential for natural recovery of abalone populations over time and that further understanding of mechanisms governing host-parasite relationships will better enable us to manage declining populations.

  14. Reduced disease in black abalone following mass mortality: phage therapy and natural selection.

    Science.gov (United States)

    Friedman, Carolyn S; Wight, Nathan; Crosson, Lisa M; Vanblaricom, Glenn R; Lafferty, Kevin D

    2014-01-01

    Black abalone, Haliotis cracherodii, populations along the NE Pacific ocean have declined due to the rickettsial disease withering syndrome (WS). Natural recovery on San Nicolas Island (SNI) of Southern California suggested the development of resistance in island populations. Experimental challenges in one treatment demonstrated that progeny of disease-selected black abalone from SNI survived better than did those from naïve black abalone from Carmel Point in mainland coastal central California. Unexpectedly, the presence of a newly observed bacteriophage infecting the WS rickettsia (WS-RLO) had strong effects on the survival of infected abalone. Specifically, presence of phage-infected RLO (RLOv) reduced the host response to infection, RLO infection loads, and associated mortality. These data suggest that the black abalone: WS-RLO relationship is evolving through dual host mechanisms of resistance to RLO infection in the digestive gland via tolerance to infection in the primary target tissue (the post-esophagus) coupled with reduced pathogenicity of the WS-RLO by phage infection, which effectively reduces the infection load in the primary target tissue by half. Sea surface temperature patterns off southern California, associated with a recent hiatus in global-scale ocean warming, do not appear to be a sufficient explanation for survival patterns in SNI black abalone. These data highlight the potential for natural recovery of abalone populations over time and that further understanding of mechanisms governing host-parasite relationships will better enable us to manage declining populations.

  15. Natural and bioremediated selective degradation of polycyclic aromatic alkyl isomers in oil-contaminated soils

    International Nuclear Information System (INIS)

    Sauer, T.C.; McCarthy, K.; Uhler, A.; Porta, A.

    1995-01-01

    In studies where 2- to 6-ring polycyclic aromatic hydrocarbons (PAHs) are determined as part of characterizing released oil constituents in environmental samples, the changes in composition of PAHs from weathering (e.g., evaporation, dissolution) and biodegradation are most often represented by PAH alkyl homologue distributions. Concentrations of PAH alkyl groups are the sum of individual PAH isomers of similar carbon number; such as for C2-naphthalenes, the C2 alkyl group consists of dimethyl and ethyl substitutions on the parent naphthalene. In weathering and degradation studies, the changes in relative concentration of the individual isomers within an alkyl group are rarely reported. In a field study of oiled soils, the authors looked at the selective losses, for a period of a year, of individual PAH alkyl isomers that occur both naturally by weathering processes and through the use of bioremediation technology. Results showed that decreases in alkyl group concentrations were not always represented by similar losses of each isomer in the alkyl group, but were often due to the preferential or selective loss of certain isomers in the group

  16. Schwann Cell Glycogen Selectively Supports Myelinated Axon Function

    Science.gov (United States)

    Brown, Angus M; Evans, Richard D; Black, Joel; Ransom, Bruce R

    2012-01-01

    Objectives Interruption of energy supply to peripheral axons is a cause of axon loss. We determined if glycogen was present in mammalian peripheral nerve, and if it supported axon conduction during aglycemia. Methods We used biochemical assay and electron microscopy to determine the presence of glycogen, and electrophysiology to monitor axon function. Results Glycogen was present in sciatic nerve, its concentration varying directly with ambient [glucose]. Electron microscopy detected glycogen granules primarily in myelinating Schwann cell cytoplasm and these diminished after exposure to aglycemia. During aglycemia, conduction failure in large myelinated axons (A fibers) mirrored the time-course of glycogen loss. Latency to CAP failure was directly related to nerve glycogen content at aglycemia onset. Glycogen did not benefit the function of slow-conducting, small diameter unmyelinated axons (C fibers) during aglycemia. Blocking glycogen breakdown pharmacologically accelerated CAP failure during aglycemia in A fibers, but not in C fibers. Lactate was as effective as glucose in supporting sciatic nerve function, and was continuously released into the extracellular space in the presence of glucose and fell rapidly during aglycemia. Interpretation Our findings indicated that glycogen is present in peripheral nerve, primarily in myelinating Schwann cells, and exclusively supports large diameter, myelinated axon conduction during aglycemia. Available evidence suggests that peripheral nerve glycogen breaks down during aglycemia and is passed, probably as lactate, to myelinated axons to support function. Unmyelinated axons are not protected by glycogen and are more vulnerable to dysfunction during periods of hypoglycemia. PMID:23034913

  17. Evaluation of selected parameters of rat liver and kidney function ...

    African Journals Online (AJOL)

    The effects of administration of yohimbine, an aphrodisiac on some functional parameters of rat liver and kidney were investigated. White male albino rats weighing between 200-250g were grouped into two such that one group was orally administered with 14mg/kg body weight on daily basis for 15days while the control ...

  18. Sex-specific effects of natural and sexual selection on the evolution of life span and ageing in Drosophila simulans

    NARCIS (Netherlands)

    Archer, C.R.; Duffy, E.; Hosken, D.J.; Mokkonen, M.; Okada, K.; Oku, K.; Sharma, M.D.; Hunt, J.

    2015-01-01

    1. Variation in the strength of age-dependent natural selection shapes differences in ageing rates across species and populations. Likewise, sexual selection can promote divergent patterns of senescence across the sexes. However, the effects of these processes on the evolution of ageing have largely

  19. Natural selection among Eurasians at genomic regions associated with HIV-1 control

    Directory of Open Access Journals (Sweden)

    Allison David B

    2011-06-01

    Full Text Available Abstract Background HIV susceptibility and pathogenicity exhibit both interindividual and intergroup variability. The etiology of intergroup variability is still poorly understood, and could be partly linked to genetic differences among racial/ethnic groups. These genetic differences may be traceable to different regimes of natural selection in the 60,000 years since the human radiation out of Africa. Here, we examine population differentiation and haplotype patterns at several loci identified through genome-wide association studies on HIV-1 control, as determined by viral-load setpoint, in European and African-American populations. We use genome-wide data from the Human Genome Diversity Project, consisting of 53 world-wide populations, to compare measures of FST and relative extended haplotype homozygosity (REHH at these candidate loci to the rest of the respective chromosome. Results We find that the Europe-Middle East and Europe-South Asia pairwise FST in the most strongly associated region are elevated compared to most pairwise comparisons with the sub-Saharan African group, which exhibit very low FST. We also find genetic signatures of recent positive selection (higher REHH at these associated regions among all groups except for sub-Saharan Africans and Native Americans. This pattern is consistent with one in which genetic differentiation, possibly due to diversifying/positive selection, occurred at these loci among Eurasians. Conclusions These findings are concordant with those from earlier studies suggesting recent evolutionary change at immunity-related genomic regions among Europeans, and shed light on the potential genetic and evolutionary origin of population differences in HIV-1 control.

  20. [Selective feeding in fish: Effect of feeding and defensive motivations evoked by natural odors].

    Science.gov (United States)

    Kasumyan, A O; Marusov, E A

    2015-01-01

    The effect of feeding and defensive motivations evoked by natural olfactory signals (the food odor, the alarm pheromone) on choice and consumption of food items different in color and taste, and the manifestation of foraging behavior were examined in fish (koi Cyprinus carpio, roach Rutilus rutilus). The agar-agar pellets of red and green color having one of the amino acids (glycine, L-proline, L-alanine; all in concentration of 0.1 M) were simultaneously offered to single fishes in pure water, and in water extract of Chironomidae larvae or in water extract of fish skin. It was found out that odors used have different effects on fish foraging activity and on pellet selection for both pellet choice and consumption. On background of food odor, fish grasped pellets more often than in pure water. The equal choice of red and green pellets in pure water shifted to the preference of red ones in the presence of food odor. Despite the increase in the absolute number of pellets grasped, the relative consumption reduced and was replaced by selective consumption of pellets with glycine regardless of their color. Increasing demand for the food quality, due to the increased feeding motivation in response to food odor, is an important adaptation enhancing selection and consumption of food with more appropriate sensory qualities for fish. Defensive motivation caused by alarm pheromone suppressed predisposition. of fish to feed. Fish grasped pellets several times less often than in pure water and refused most of them. Any changes in the color or taste preferences were absent. Feeding behavior of fish of both species was characterized by repeated intraoral pellet testing, but in koi handling was less typical than in roach. In both species, handling activity was higher in those cases when the pellet was finally rejected. This activity was enhanced also on the background of food odor.

  1. Selected personality traits and achievement motivation in university students of physical culture, education and natural sciences

    Directory of Open Access Journals (Sweden)

    Martin Sigmund

    2013-09-01

    Full Text Available BACKGROUND: Understanding personality variables and other important psychological traits in the university population appears topical particularly with respect to personality, motivation, health as well as overall academic achievement. A significant role is played by correlations of the monitored variables in relation to selected study specialization. OBJECTIVE: The main objective of the present study is to extend the knowledge on selected personality traits and the level of achievement motivation in a specific group of university students with respect to the diversity of their study specialization. METHODS: The study included a total of 522 students from Palacký University. These were students from the Faculty of Physical Culture (n = 118, Faculty of Education (n = 218 and Faculty of Science (n = 186. In terms of age, the study focused on young adults aged 19 to 26. In the research, psychodiagnostic methods were used to perform diagnostics and to fulfil the overall research plan. All diagnostic methods used are fully standardized and contain domestic normative values. We monitored variables such as personality, achievement motivation and achievement anxiety. Statistical result processing was conducted using the Statgraphics programme v. 9.0. Result processing was made using parametric as well as non-parametric statistical methods (Shapiro-Wilk, Mann-Whitney, Kruskal-Wallis, Spearman’s correlation. RESULTS: University students specialized in physical culture showed the highest values of extraversion and psychoticism, and clearly the lowest values of neuroticism compared to the students of education and natural sciences. The highest values of openness were observed in the students specialized in sports. In terms of the overall achievement motivation related to study specialization, almost identical values were observed. However, the students of physical culture showed significantly lower values of achievement debilitating anxiety

  2. The roles of the analogy with natural selection in B.F. Skinner's philosophy.

    Science.gov (United States)

    Smith, Terry L

    2018-02-17

    Beginning in the 1950s, B.F. Skinner made increasing reference to an analogy between operant conditioning and natural selection. This analogy is the basis of an argument that, in contrast to Skinner's other critiques of cognitive science, is neither epistemological nor pragmatic. Instead, it is based on the claim that ontogenetic adaptation is due to a special mode of causation he called "selection by consequences." He argued that this mode of causation conflicts with explanations that attribute action to an autonomous agent with reasons for acting. This argument dismisses ordinary explanations of action, and has implications not only for cognitive science but also for morals. Skinner cited the latter implications to counter objections to the application of behavior analysis to the reform of society and its institutions. Skinner's critique, however, rests upon empirical assumptions that have been criticized by other behavior analysts. Although for Skinner the major role of the analogy was to propose an empirical thesis, it also can play a metaphysical role-namely, to demonstrate the possibility of ontogenetic adaptation without reference to agents who have reasons for acting. These two roles, empirical and metaphysical, are the mirror image of the empirical and metaphysical roles of the computer analogy for cognitive science. That analogy also can be (and has been) interpreted as an empirical thesis. Its empirical implications, however, have been difficult to confirm. It also, however, has played a metaphysical role-namely, to demonstrate the possibility that a physical process could perform logical operations on states having propositional content. Neither analogy provides a well-confirmed, general answer to the question of how to explain the process of ontogenetic adaptation. But together they show there are two metaphysically coherent, but conflicting, answers to this question. Depending upon one's epistemology, the analogy with natural selection may provide a

  3. Relation of desert pupfish abundance to selected environmental variables in natural and manmade habitats in the Salton Sea basin

    Science.gov (United States)

    Martin, B.A.; Saiki, M.K.

    2005-01-01

    We assessed the relation between abundance of desert pupfish, Cyprinodon macularius, and selected biological and physicochemical variables in natural and manmade habitats within the Salton Sea Basin. Field sampling in a natural tributary, Salt Creek, and three agricultural drains captured eight species including pupfish (1.1% of the total catch), the only native species encountered. According to Bray-Curtis resemblance functions, fish species assemblages differed mostly between Salt Creek and the drains (i.e., the three drains had relatively similar species assemblages). Pupfish numbers and environmental variables varied among sites and sample periods. Canonical correlation showed that pupfish abundance was positively correlated with abundance of western mosquitofish, Gambusia affinis, and negatively correlated with abundance of porthole livebearers, Poeciliopsis gracilis, tilapias (Sarotherodon mossambica and Tilapia zillii), longjaw mudsuckers, Gillichthys mirabilis, and mollies (Poecilia latipinnaandPoecilia mexicana). In addition, pupfish abundance was positively correlated with cover, pH, and salinity, and negatively correlated with sediment factor (a measure of sediment grain size) and dissolved oxygen. Pupfish abundance was generally highest in habitats where water quality extremes (especially high pH and salinity, and low dissolved oxygen) seemingly limited the occurrence of nonnative fishes. This study also documented evidence of predation by mudsuckers on pupfish. These findings support the contention of many resource managers that pupfish populations are adversely influenced by ecological interactions with nonnative fishes. ?? Springer 2005.

  4. Microbes in the Anthropocene: spillover of agriculturally selected bacteria and their impact on natural ecosystems.

    Science.gov (United States)

    Bell, Thomas; Tylianakis, Jason M

    2016-12-14

    Soil microbial communities are enormously diverse, with at least millions of species and trillions of genes unknown to science or poorly described. Soil microbial communities are key components of agriculture, for example, in provisioning nitrogen and protecting crops from pathogens, providing overall ecosystem services in excess of $1000bn per year. It is important to know how humans are affecting this hidden diversity. Much is known about the negative consequences of agricultural intensification on higher organisms, but almost nothing is known about how alterations to landscapes affect microbial diversity, distributions and processes. We review what is known about spatial flows of microbes and their response to land-use change, and outline nine hypotheses to advance research of microbiomes across landscapes. We hypothesize that intensified agriculture selects for certain taxa and genes, which then 'spill over' into adjacent unmodified areas and generate a halo of genetic differentiation around agricultural fields. Consequently, the spatial configuration and management intensity of different habitats combines with the dispersal ability of individual taxa to determine the extent of spillover, which can impact the functioning of adjacent unmodified habitats. When landscapes are heterogeneous and dispersal rates are high, this will select for large genomes that allow exploitation of multiple habitats, a process that may be accelerated through horizontal gene transfer. Continued expansion of agriculture will increase genotypic similarity, making microbial community functioning increasingly variable in human-dominated landscapes, potentially also impacting the consistent provisioning of ecosystem services. While the resulting economic costs have not been calculated, it is clear that dispersal dynamics of microbes should be taken into consideration to ensure that ecosystem functioning and services are maintained in agri-ecosystem mosaics. © 2016 The Authors.

  5. Microbes in the Anthropocene: spillover of agriculturally selected bacteria and their impact on natural ecosystems

    Science.gov (United States)

    2016-01-01

    Soil microbial communities are enormously diverse, with at least millions of species and trillions of genes unknown to science or poorly described. Soil microbial communities are key components of agriculture, for example, in provisioning nitrogen and protecting crops from pathogens, providing overall ecosystem services in excess of $1000bn per year. It is important to know how humans are affecting this hidden diversity. Much is known about the negative consequences of agricultural intensification on higher organisms, but almost nothing is known about how alterations to landscapes affect microbial diversity, distributions and processes. We review what is known about spatial flows of microbes and their response to land-use change, and outline nine hypotheses to advance research of microbiomes across landscapes. We hypothesize that intensified agriculture selects for certain taxa and genes, which then ‘spill over’ into adjacent unmodified areas and generate a halo of genetic differentiation around agricultural fields. Consequently, the spatial configuration and management intensity of different habitats combines with the dispersal ability of individual taxa to determine the extent of spillover, which can impact the functioning of adjacent unmodified habitats. When landscapes are heterogeneous and dispersal rates are high, this will select for large genomes that allow exploitation of multiple habitats, a process that may be accelerated through horizontal gene transfer. Continued expansion of agriculture will increase genotypic similarity, making microbial community functioning increasingly variable in human-dominated landscapes, potentially also impacting the consistent provisioning of ecosystem services. While the resulting economic costs have not been calculated, it is clear that dispersal dynamics of microbes should be taken into consideration to ensure that ecosystem functioning and services are maintained in agri-ecosystem mosaics. PMID:27928044

  6. Using step and path selection functions for estimating resistance to movement: Pumas as a case study

    Science.gov (United States)

    Katherine A. Zeller; Kevin McGarigal; Samuel A. Cushman; Paul Beier; T. Winston Vickers; Walter M. Boyce

    2015-01-01

    GPS telemetry collars and their ability to acquire accurate and consistently frequent locations have increased the use of step selection functions (SSFs) and path selection functions (PathSFs) for studying animal movement and estimating resistance. However, previously published SSFs and PathSFs often do not accommodate multiple scales or multiscale modeling....

  7. Use of Behavior and Influence Functions for Relay Selection in Cooperative Communications

    DEFF Research Database (Denmark)

    Craciunescu, Razvan; Mihovska, Albena Dimitrova; Prasad, Ramjee

    2015-01-01

    This paper uses a novel set of functions to model the relay selection process in a scenario of cooperative wireless communications. We define a utility function that reflects the behavior and influence that a selected relay may have on the quality of the link to be established for the forwarding...... of data. The utility function takes into account also the strategies of other players. To this end, we define a relay selection game and a supporting Nash Equilibrium (NE) algorithm for the choice of a relay during communication. The successful selection of a relay is evaluated by simulations in terms...

  8. Functional divergence caused by ancient positive selection of a Drosophila hybrid incompatibility locus.

    Directory of Open Access Journals (Sweden)

    Daniel A Barbash

    2004-06-01

    Full Text Available Interspecific hybrid lethality and sterility are a consequence of divergent evolution between species and serve to maintain the discrete identities of species. The evolution of hybrid incompatibilities has been described in widely accepted models by Dobzhansky and Muller where lineage-specific functional divergence is the essential characteristic of hybrid incompatibility genes. Experimentally tractable models are required to identify and test candidate hybrid incompatibility genes. Several Drosophila melanogaster genes involved in hybrid incompatibility have been identified but none has yet been shown to have functionally diverged in accordance with the Dobzhansky-Muller model. By introducing transgenic copies of the X-linked Hybrid male rescue (Hmr gene into D. melanogaster from its sibling species D. simulans and D. mauritiana, we demonstrate that Hmr has functionally diverged to cause F1 hybrid incompatibility between these species. Consistent with the Dobzhansky-Muller model, we find that Hmr has diverged extensively in the D. melanogaster lineage, but we also find extensive divergence in the sibling-species lineage. Together, these findings implicate over 13% of the amino acids encoded by Hmr as candidates for causing hybrid incompatibility. The exceptional level of divergence at Hmr cannot be explained by neutral processes because we use phylogenetic methods and population genetic analyses to show that the elevated amino-acid divergence in both lineages is due to positive selection in the distant past-at least one million generations ago. Our findings suggest that multiple substitutions driven by natural selection may be a general phenomenon required to generate hybrid incompatibility alleles.

  9. Thermodynamic selectivity of functional agents on zeolite for sodium dodecyl sulfate sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Leng, Ling; Wang, Jian [Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR (China); Qiu, Xianxiu; Zhao, Yanxiang; Yip, Yuk-Wang; Law, Ga-Lai [Department of Applied Biology and Chemical Technology, State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR (China); Shih, Kaimin; Zhou, Zhengyuan [Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, Hong Kong SAR (China); Lee, Po-Heng, E-mail: poheng76@gmail.com [Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR (China)

    2016-11-15

    Highlights: • A thermodynamic approach to select a functional agent for adsorbent is proposed. • ITC and QCS were used to interpret the interaction between adsorbate and agent. • The interaction identifies the adsorption mechanism and performance. • This approach enables the manipulation of adsorption capacity optimization. - Abstract: This study proposes a thermodynamic approach to effectively select functional agents onto zeolite for sodium dodecyl sulfate (SDS) sequestration in greywater reuse. We combine isothermal titration calorimetry (ITC) and quantum chemistry simulation (QCS) to identify the interactions between SDS and agents at the molecular level. Three potential agents, cetyl trimethyl ammonium bromide (CTAB), N,N,N-trimethyltetradecan-1-aminium bromide (C{sub 14}TAB), and 14-hydroxy-N,N,N-trimethyltetradecan-1-aminium bromide (C{sub 14}HTAB), differ in carbon chain length and hydrophilic groups. The ITC titration of SDS with CTAB released the highest heat, followed by those with C{sub 14}TAB and C{sub 14}HTAB, as was the same trend for the amounts of SDS adsorbed by the respective functionalized-zeolites. Results suggest that the favorable SDS sorption occurred at the bilayer CTAB-zeolite is driven by enthalpy as similar as the SDS…CTAB interaction found, regardless of the contribution from electrostatic and/or hydrophobic behaviors, while the declined sorption is entropy-driven via the predominant hydrophobic interaction onto the monolayer CTAB-zeolite. The data presented here interpret the nature of molecularly thermodynamic quantities and enable the manipulation of sorption capacity optimization.

  10. Analysis of selected reservoirs functioning in the Wielkopolska region

    Directory of Open Access Journals (Sweden)

    Mariusz Sojka

    2017-12-01

    Full Text Available The paper presents the problems related to the functioning of reservoirs in the Wielkopolska province and suggests their possible solutions. The reservoirs chosen as examples include typical dam constructions with a single water body (Jeziorsko, Rydzyna, two water body objects with separated preliminary part (Stare Miasto, Kowalskie, Radzyny and lateral constructions (Pakosław, Jutrosin. The reservoirs were built in period from 1970 to 2014. They differ in construction, functions and water management rules. Analysis of the main problems related to the reservoir functioning is aimed at finding ways of improving the construction of new reservoirs that would satisfy increasingly stringent environmental and legal restrictions and the methods of water management in the reservoirs. On the basis of a questionnaire filled in by the reservoir operators, the main problem is water quality. Especially the huge inflow of biogenic compounds causes blooms of algae and overgrowth with riparian vegetation. Some difficulties are also related to management of the reservoirs of multi-purpose operation. It is difficult to take into account the requirements of environmental flow maintenance, flood protection, water supply for agriculture and water use for tourism and recreation and hydropower generation, etc.

  11. Did natural selection make the Dutch taller? A cautionary note on the importance of quantification in understanding evolution.

    Science.gov (United States)

    Tarka, Maja; Bolstad, Geir H; Wacker, Sebastian; Räsänen, Katja; Hansen, Thomas F; Pélabon, Christophe

    2015-12-01

    One of the main achievements of the modern synthesis is a rigorous mathematical theory for evolution by natural selection. Combining this theory with statistical models makes it possible to estimate the relevant parameters so as to quantify selection and evolution in nature. Although quantification is a sign of a mature science, statistical models are unfortunately often interpreted independently of the motivating mathematical theory. Without a link to theory, numerical results do not represent proper quantifications, because they lack the connections that designate their biological meaning. Here, we want to raise awareness and exemplify this problem by examining a recent study on natural selection in a contemporary human population. Stulp et al. (2015) concluded that natural selection may partly explain the increasing stature of the Dutch population. This conclusion was based on a qualitative assessment of the presence of selection on height. Here, we provide a quantitative interpretation of these results using standard evolutionary theory to show that natural selection has had a minuscule effect. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  12. Adaptive value of phenological traits in stressful environments: predictions based on seed production and laboratory natural selection.

    Directory of Open Access Journals (Sweden)

    Benjamin Brachi

    Full Text Available Phenological traits often show variation within and among natural populations of annual plants. Nevertheless, the adaptive value of post-anthesis traits is seldom tested. In this study, we estimated the adaptive values of pre- and post-anthesis traits in two stressful environments (water stress and interspecific competition, using the selfing annual species Arabidopsis thaliana. By estimating seed production and by performing laboratory natural selection (LNS, we assessed the strength and nature (directional, disruptive and stabilizing of selection acting on phenological traits in A. thaliana under the two tested stress conditions, each with four intensities. Both the type of stress and its intensity affected the strength and nature of selection, as did genetic constraints among phenological traits. Under water stress, both experimental approaches demonstrated directional selection for a shorter life cycle, although bolting time imposes a genetic constraint on the length of the interval between bolting and anthesis. Under interspecific competition, results from the two experimental approaches showed discrepancies. Estimation of seed production predicted directional selection toward early pre-anthesis traits and long post-anthesis periods. In contrast, the LNS approach suggested neutrality for all phenological traits. This study opens questions on adaptation in complex natural environment where many selective pressures act simultaneously.

  13. Protective Controller against Cascade Outages with Selective Harmonic Compensation Function

    Science.gov (United States)

    Abramovich, B. N.; Kuznetsov, P. A.; Sychev, Yu A.

    2018-05-01

    The paper presents data on the power quality and development of protective devices for the power networks with distributed generation (DG).The research has shown that power quality requirements for DG networks differ from conventional ones. That is why main tendencies, protective equipment and filters should be modified. There isa developed algorithm for detection and prevention of cascade outages that can lead to the blackoutin DG networks and there was a proposed structural scheme for a new active power filter for selective harmonics compensation. Analysis of these theories and equipment led to the development of protective device that could monitor power balance and cut off non-important consumers. The last part of the article describes a microcontroller prototype developed for connection to the existing power station control center.

  14. Infrared dielectric function of polydimethylsiloxane and selective emission behavior

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, Arvind; Czapla, Braden; Narayanaswamy, Arvind, E-mail: arvind.narayanaswamy@columbia.edu [Department of Mechanical Engineering, Columbia University, New York, New York 10027 (United States); Mayo, Jeff [Skycatch, San Francisco, California 94107 (United States)

    2016-08-08

    The complex refractive index of polydimethylsiloxane (PDMS) is determined in the wavelength range between 2.5 μm and 16.7 μm. The parameters of a Drude-Lorentz oscillator model (with 15 oscillators) are extracted from Fourier transform infrared spectroscopy reflectance measurements made on both bulk PDMS and thin films of PDMS deposited on the gold coated silicon substrates. It is shown that thin films of PDMS atop gold exhibit selective emission in the 8 μm to 13 μm atmospheric transmittance window, which demonstrates that PDMS, especially due to its ease of deposition, may be a viable material for passive radiative cooling applications.

  15. Natural History of Thyroid Function in Adults with Down Syndrome--10-Year Follow-Up Study

    Science.gov (United States)

    Prasher, V.; Gomez, G.

    2007-01-01

    Background: The natural history of thyroid function in adults with Down syndrome (DS) is unknown. Method: This study investigated annual thyroid function tests in 200 adults with DS over a 10-year period. Results: Transient and persistent thyroid dysfunction was common. The 5- and 10-year incidence of definite hypothyroidism was 0.9%-1.64% and…

  16. Parameter Selection Method for Support Vector Regression Based on Adaptive Fusion of the Mixed Kernel Function

    Directory of Open Access Journals (Sweden)

    Hailun Wang

    2017-01-01

    Full Text Available Support vector regression algorithm is widely used in fault diagnosis of rolling bearing. A new model parameter selection method for support vector regression based on adaptive fusion of the mixed kernel function is proposed in this paper. We choose the mixed kernel function as the kernel function of support vector regression. The mixed kernel function of the fusion coefficients, kernel function parameters, and regression parameters are combined together as the parameters of the state vector. Thus, the model selection problem is transformed into a nonlinear system state estimation problem. We use a 5th-degree cubature Kalman filter to estimate the parameters. In this way, we realize the adaptive selection of mixed kernel function weighted coefficients and the kernel parameters, the regression parameters. Compared with a single kernel function, unscented Kalman filter (UKF support vector regression algorithms, and genetic algorithms, the decision regression function obtained by the proposed method has better generalization ability and higher prediction accuracy.

  17. The nature of expertise and human resource functions supporting expertise in nuclear industry organizations

    International Nuclear Information System (INIS)

    Rintala, N.; Katri, S.; Eila, J.; Pahkin, K.; Anneli, L.

    2007-01-01

    Full text: The nuclear industry worldwide faces the challenge of preserving the existing expertise, competence and knowledge despite of the ageing workforce and upcoming retirements. Challenges are also imposed by the reducing amount of new recruits and students entering the nuclear industry, which amounts to fewer young professionals that have the potential to become nuclear experts in the future. Although many other industries share similar challenges, the preservation of expertise in the nuclear industry is even more important due to the safety-critical nature of the nuclear operations and the special characteristics that high-reliability organizations such as nuclear power plants have. As a response to the risk of knowledge loss, nuclear organizations have engaged in knowledge capturing efforts. New information systems and organizational practices have been implemented to safeguard nuclear expertise. Recently, IAEA has proposed nuclear organizations to design and adopt people-centered programs that encompass themes such as workforce planning, recruitment, training, succession planning, leadership development and knowledge management. Thus, in order to address the current risks to nuclear expertise, attention should be focused on these different areas and corresponding human resources (HR) functions within the nuclear organizations. Our paper presents results from a project which examines the nature of expert work and human resources (HR) functions that support the development and preservation of expertise. The study adopts a qualitative cross-sectional case study design. Two organizational units from different nuclear industry organizations have been selected as cases. The research data will be gathered in April-May 2007 and preliminary results will be presented in the International Conference of Knowledge Management in Nuclear Facilities, in June 2007. The main data will comprise of thematic interviews to experts, their managers and HR representatives

  18. Natural Killer Cell Function and Dysfunction in Hepatitis C Virus Infection

    Directory of Open Access Journals (Sweden)

    Kayla A. Holder

    2014-01-01

    Full Text Available Viruses must continually adapt against dynamic innate and adaptive responses of the host immune system to establish chronic infection. Only a small minority (~20% of those exposed to hepatitis C virus (HCV spontaneously clear infection, leaving approximately 200 million people worldwide chronically infected with HCV. A number of recent research studies suggest that establishment and maintenance of chronic HCV infection involve natural killer (NK cell dysfunction. This relationship is illustrated in vitro by disruption of typical NK cell responses including both cell-mediated cytotoxicity and cytokine production. Expression of a number of activating NK cell receptors in vivo is also affected in chronic HCV infection. Thus, direct in vivo and in vitro evidence of compromised NK function in chronic HCV infection in conjunction with significant epidemiological associations between the outcome of HCV infection and certain combinations of NK cell regulatory receptor and class I human histocompatibility linked antigen (HLA genotypes indicate that NK cells are important in the immune response against HCV infection. In this review, we highlight evidence suggesting that selective impairment of NK cell activity is related to establishment of chronic HCV infection.

  19. Functional Neuroanatomy Associated with Natural and Urban Scenic Views in the Human Brain: 3.0T Functional MR Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gwang Won; Jeong, Gwang Woo; Kim, Tae Hoon; Baek, Han Su; Oh, Seok Kyun; Kang, Heoung Keun; Lee, Sam Gyu; Kim, Yoon Soo; Song, Jin Kyu [Chonnam National University, Gwangju (Korea, Republic of)

    2010-10-15

    By using a functional magnetic resonance imaging (fMRI) technique we assessed brain activation patterns while subjects were viewing the living environments representing natural and urban scenery. A total of 28 healthy right-handed subjects underwent an fMRI on a 3.0 Tesla MRI scanner. The stimulation paradigm consisted of three times the rest condition and two times the activation condition, each of which lasted for 30 and 120 seconds, respectively. During the activation period, each subject viewed natural and urban scenery, respectively. The predominant brain activation areas observed following exposure to natural scenic views in contrast with urban views included the superior and middle frontal gyri, superior parietal gyrus, precuneus, basal ganglia, superior occipital gyrus, anterior cingulate gyrus, superior temporal gyrus, and insula. On the other hand, the predominant brain activation areas following exposure to urban scenic views in contrast with natural scenes included the middle and inferior occipital gyri, parahippocampal gyrus, hippocampus, amygdala, anterior temporal pole, and inferior frontal gyrus. Our findings support the idea that the differential functional neuroanatomies for each scenic view are presumably related with subjects emotional responses to the natural and urban environment, and thus the differential functional neuroanatomy can be utilized as a neural index for the evaluation of friendliness in ecological housing

  20. Functional Neuroanatomy Associated with Natural and Urban Scenic Views in the Human Brain: 3.0T Functional MR Imaging

    International Nuclear Information System (INIS)

    Kim, Gwang Won; Jeong, Gwang Woo; Kim, Tae Hoon; Baek, Han Su; Oh, Seok Kyun; Kang, Heoung Keun; Lee, Sam Gyu; Kim, Yoon Soo; Song, Jin Kyu

    2010-01-01

    By using a functional magnetic resonance imaging (fMRI) technique we assessed brain activation patterns while subjects were viewing the living environments representing natural and urban scenery. A total of 28 healthy right-handed subjects underwent an fMRI on a 3.0 Tesla MRI scanner. The stimulation paradigm consisted of three times the rest condition and two times the activation condition, each of which lasted for 30 and 120 seconds, respectively. During the activation period, each subject viewed natural and urban scenery, respectively. The predominant brain activation areas observed following exposure to natural scenic views in contrast with urban views included the superior and middle frontal gyri, superior parietal gyrus, precuneus, basal ganglia, superior occipital gyrus, anterior cingulate gyrus, superior temporal gyrus, and insula. On the other hand, the predominant brain activation areas following exposure to urban scenic views in contrast with natural scenes included the middle and inferior occipital gyri, parahippocampal gyrus, hippocampus, amygdala, anterior temporal pole, and inferior frontal gyrus. Our findings support the idea that the differential functional neuroanatomies for each scenic view are presumably related with subjects emotional responses to the natural and urban environment, and thus the differential functional neuroanatomy can be utilized as a neural index for the evaluation of friendliness in ecological housing

  1. Amyloid Fibrils as Building Blocks for Natural and Artificial Functional Materials.

    Science.gov (United States)

    Knowles, Tuomas P J; Mezzenga, Raffaele

    2016-08-01

    Proteinaceous materials based on the amyloid core structure have recently been discovered at the origin of biological functionality in a remarkably diverse set of roles, and attention is increasingly turning towards such structures as the basis of artificial self-assembling materials. These roles contrast markedly with the original picture of amyloid fibrils as inherently pathological structures. Here we outline the salient features of this class of functional materials, both in the context of the functional roles that have been revealed for amyloid fibrils in nature, as well as in relation to their potential as artificial materials. We discuss how amyloid materials exemplify the emergence of function from protein self-assembly at multiple length scales. We focus on the connections between mesoscale structure and material function, and demonstrate how the natural examples of functional amyloids illuminate the potential applications for future artificial protein based materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Electromyographic control of functional electrical stimulation in selected patients.

    Science.gov (United States)

    Graupe, D; Kohn, K H; Basseas, S; Naccarato, E

    1984-07-01

    The paper describes initial results of above-lesion electromyographic (EMG) controlled functional electrical stimulation (FES) of paraplegics. Such controlled stimulation is to provide upper-motor-neuron paraplegics (T5 to T12) with self-controlled standing and some walking without braces and with only the help of walkers or crutches. The above-lesion EMG signal employed serves to map the posture of the patient's upper trunk via a computerized mapping of the temporal patterns of that EMG. Such control also has an inherent safety feature in that it prevents the patient from performing a lower-limb movement via FES unless his trunk posture is adequate. Copyright 2013, SLACK Incorporated.

  3. Diversity in the glucose transporter-4 gene (SLC2A4 in humans reflects the action of natural selection along the old-world primates evolution.

    Directory of Open Access Journals (Sweden)

    Eduardo Tarazona-Santos

    Full Text Available BACKGROUND: Glucose is an important source of energy for living organisms. In vertebrates it is ingested with the diet and transported into the cells by conserved mechanisms and molecules, such as the trans-membrane Glucose Transporters (GLUTs. Members of this family have tissue specific expression, biochemical properties and physiologic functions that together regulate glucose levels and distribution. GLUT4 -coded by SLC2A4 (17p13 is an insulin-sensitive transporter with a critical role in glucose homeostasis and diabetes pathogenesis, preferentially expressed in the adipose tissue, heart muscle and skeletal muscle. We tested the hypothesis that natural selection acted on SLC2A4. METHODOLOGY/PRINCIPAL FINDINGS: We re-sequenced SLC2A4 and genotyped 104 SNPs along a approximately 1 Mb region flanking this gene in 102 ethnically diverse individuals. Across the studied populations (African, European, Asian and Latin-American, all the eight common SNPs are concentrated in the N-terminal region upstream of exon 7 ( approximately 3700 bp, while the C-terminal region downstream of intron 6 ( approximately 2600 bp harbors only 6 singletons, a pattern that is not compatible with neutrality for this part of the gene. Tests of neutrality based on comparative genomics suggest that: (1 episodes of natural selection (likely a selective sweep predating the coalescent of human lineages, within the last 25 million years, account for the observed reduced diversity downstream of intron 6 and, (2 the target of natural selection may not be in the SLC2A4 coding sequence. CONCLUSIONS: We propose that the contrast in the pattern of genetic variation between the N-terminal and C-terminal regions are signatures of the action of natural selection and thus follow-up studies should investigate the functional importance of different regions of the SLC2A4 gene.

  4. Review of selected dynamic material control functions for international safeguards

    International Nuclear Information System (INIS)

    Lowry, L.L.

    1980-09-01

    With the development of Dynamic Special Nuclear Material Accounting and Control systems used in nuclear manufacturing and reprocessing plants, there arises the question as to how these systems affect the IAEA inspection capabilities. The systems in being and under development provide information and control for a variety of purposes important to the plant operator, the safeguards purpose being one of them. This report attempts to judge the usefulness of these dynamic systems to the IAEA and have defined 12 functions that provide essential information to it. If the information acquired by these dynamic systems is to be useful to the IAEA, the inspectors must be able to independently verify it. Some suggestions are made as to how this might be done. But, even if it should not be possible to verify all the data, the availability to the IAEA of detailed, simultaneous, and plant-wide information would tend to inhibit a plant operator from attempting to generate a floating or fictitious inventory. Suggestions are made that might be helpful in the design of future software systems, an area which has proved to be fatally deficient in some systems and difficult in all

  5. Functional conservation of nucleosome formation selectively biases presumably neutral molecular variation in yeast genomes.

    Science.gov (United States)

    Babbitt, Gregory A; Cotter, C R

    2011-01-01

    One prominent pattern of mutational frequency, long appreciated in comparative genomics, is the bias of purine/pyrimidine conserving substitutions (transitions) over purine/pyrimidine altering substitutions (transversions). Traditionally, this transitional bias has been thought to be driven by the underlying rates of DNA mutation and/or repair. However, recent sequencing studies of mutation accumulation lines in model organisms demonstrate that substitutions generally do not accumulate at rates that would indicate a transitional bias. These observations have called into question a very basic assumption of molecular evolution; that naturally occurring patterns of molecular variation in noncoding regions accurately reflect the underlying processes of randomly accumulating neutral mutation in nuclear genomes. Here, in Saccharomyces yeasts, we report a very strong inverse association (r = -0.951, P < 0.004) between the genome-wide frequency of substitutions and their average energetic effect on nucleosome formation, as predicted by a structurally based energy model of DNA deformation around the nucleosome core. We find that transitions occurring at sites positioned nearest the nucleosome surface, which are believed to function most importantly in nucleosome formation, alter the deformation energy of DNA to the nucleosome core by only a fraction of the energy changes typical of most transversions. When we examined the same substitutions set against random background sequences as well as an existing study reporting substitutions arising in mutation accumulation lines of Saccharomyces cerevisiae, we failed to find a similar relationship. These results support the idea that natural selection acting to functionally conserve chromatin organization may contribute significantly to genome-wide transitional bias, even in noncoding regions. Because nucleosome core structure is highly conserved across eukaryotes, our observations may also help to further explain locally elevated

  6. Triptycene dimethyl-bridgehead dianhydride-based intrinsically microporous hydroxyl-functionalized polyimide for natural gas upgrading

    KAUST Repository

    Alghunaimi, Fahd

    2016-07-28

    The synthesis and gas permeation properties of a high-performance hydroxyl-functionalized PIM-polyimide (TDA1-APAF) prepared from a novel 9,10-dimethyl-2,3,6,7-triptycene tetracarboxylic dianhydride (TDA1) and a commercially available 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (APAF) diamine monomer are reported. The microporous polymer had a BET surface area based on nitrogen adsorption of 260 m2 g−1. A freshly prepared sample exhibited excellent gas permeation properties: (i) CO2 permeability of 40 Barrer coupled with a CO2/CH4 selectivity of 55 and (ii) H2 permeability of 94 Barrer with a H2/CH4 selectivity of 129. Physical aging over 250 days resulted in significantly enhanced CO2/CH4 and H2/CH4 selectivities of 75 and 183, respectively with only ~ 25% loss in CO2 and H2 permeability. Aged TDA1-APAF exhibited 5-fold higher pure-gas CO2 permeability (30 Barrer) and two-fold higher CO2/CH4 permselectivity over conventional dense cellulose triacetate membranes at 2 bar. In addition, TDA1-APAF polyimide had a N2/CH4 selectivity of 2.3, thereby making it potentially possible to bring natural gas with low, but unacceptable nitrogen content to pipeline specification. Gas mixture permeation experiments with a 1:1 CO2/CH4 feed mixture demonstrated higher mixed- than pure-gas selectivity and plasticization resistance up to 30 bar. These results suggest that intrinsically microporous hydroxyl-functionalized triptycene-based polyimides are promising candidate membrane materials for removal of CO2 from natural gas and hydrogen purification in petrochemical refinery applications.

  7. Calibration Variable Selection and Natural Zero Determination for Semispan and Canard Balances

    Science.gov (United States)

    Ulbrich, Norbert M.

    2013-01-01

    Independent calibration variables for the characterization of semispan and canard wind tunnel balances are discussed. It is shown that the variable selection for a semispan balance is determined by the location of the resultant normal and axial forces that act on the balance. These two forces are the first and second calibration variable. The pitching moment becomes the third calibration variable after the normal and axial forces are shifted to the pitch axis of the balance. Two geometric distances, i.e., the rolling and yawing moment arms, are the fourth and fifth calibration variable. They are traditionally substituted by corresponding moments to simplify the use of calibration data during a wind tunnel test. A canard balance is related to a semispan balance. It also only measures loads on one half of a lifting surface. However, the axial force and yawing moment are of no interest to users of a canard balance. Therefore, its calibration variable set is reduced to the normal force, pitching moment, and rolling moment. The combined load diagrams of the rolling and yawing moment for a semispan balance are discussed. They may be used to illustrate connections between the wind tunnel model geometry, the test section size, and the calibration load schedule. Then, methods are reviewed that may be used to obtain the natural zeros of a semispan or canard balance. In addition, characteristics of three semispan balance calibration rigs are discussed. Finally, basic requirements for a full characterization of a semispan balance are reviewed.

  8. Selection of yeasts with multifunctional features for application as starters in natural black table olive processing.

    Science.gov (United States)

    Bonatsou, S; Benítez, A; Rodríguez-Gómez, F; Panagou, E Z; Arroyo-López, F N

    2015-04-01

    Yeasts are unicellular eukaryotic microorganisms with a great importance in the elaboration on many foods and beverages. In the last years, researches have focused their attention to determine the favourable effects that these microorganisms could provide to table olive processing. In this context, the present study assesses, at laboratory scale, the potential technological (resistance to salt, lipase, esterase and β-glucosidase activities) and probiotic (phytase activity, survival to gastric and pancreatic digestions) features of 12 yeast strains originally isolated from Greek natural black table olive fermentations. The multivariate classification analysis carried out with all information obtained (a total of 336 quantitative input data), revealed that the most promising strains (clearly discriminated from the rest of isolates) were Pichia guilliermondii Y16 (which showed overall the highest resistance to salt and simulated digestions) and Wickerhamomyces anomalus Y18 (with the overall highest technological enzymatic activities), while the rest of strains were grouped together in two clearly differentiated clusters. Thus, this work opens the possibility for the evaluation of these two selected yeasts as multifunctional starters, alone or in combination with lactic acid bacteria, in real table olive fermentations. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Spatially variable natural selection and the divergence between parapatric subspecies of lodgepole pine (Pinus contorta, Pinaceae).

    Science.gov (United States)

    Eckert, Andrew J; Shahi, Hurshbir; Datwyler, Shannon L; Neale, David B

    2012-08-01

    Plant populations arrayed across sharp environmental gradients are ideal systems for identifying the genetic basis of ecologically relevant phenotypes. A series of five uplifted marine terraces along the northern coast of California represents one such system where morphologically distinct populations of lodgepole pine (Pinus contorta) are distributed across sharp soil gradients ranging from fertile soils near the coast to podzolic soils ca. 5 km inland. A total of 92 trees was sampled across four coastal marine terraces (N = 10-46 trees/terrace) located in Mendocino County, California and sequenced for a set of 24 candidate genes for growth and responses to various soil chemistry variables. Statistical analyses relying on patterns of nucleotide diversity were employed to identify genes whose diversity patterns were inconsistent with three null models. Most genes displayed patterns of nucleotide diversity that were consistent with null models (N = 19) or with the presence of paralogs (N = 3). Two genes, however, were exceptional: an aluminum responsive ABC-transporter with F(ST) = 0.664 and an inorganic phosphate transporter characterized by divergent haplotypes segregating at intermediate frequencies in most populations. Spatially variable natural selection along gradients of aluminum and phosphate ion concentrations likely accounted for both outliers. These results shed light on some of the genetic components comprising the extended phenotype of this ecosystem, as well as highlight ecotones as fruitful study systems for the detection of adaptive genetic variants.

  10. Stochastic noncooperative and cooperative evolutionary game strategies of a population of biological networks under natural selection.

    Science.gov (United States)

    Chen, Bor-Sen; Yeh, Chin-Hsun

    2017-12-01

    We review current static and dynamic evolutionary game strategies of biological networks and discuss the lack of random genetic variations and stochastic environmental disturbances in these models. To include these factors, a population of evolving biological networks is modeled as a nonlinear stochastic biological system with Poisson-driven genetic variations and random environmental fluctuations (stimuli). To gain insight into the evolutionary game theory of stochastic biological networks under natural selection, the phenotypic robustness and network evolvability of noncooperative and cooperative evolutionary game strategies are discussed from a stochastic Nash game perspective. The noncooperative strategy can be transformed into an equivalent multi-objective optimization problem and is shown to display significantly improved network robustness to tolerate genetic variations and buffer environmental disturbances, maintaining phenotypic traits for longer than the cooperative strategy. However, the noncooperative case requires greater effort and more compromises between partly conflicting players. Global linearization is used to simplify the problem of solving nonlinear stochastic evolutionary games. Finally, a simple stochastic evolutionary model of a metabolic pathway is simulated to illustrate the procedure of solving for two evolutionary game strategies and to confirm and compare their respective characteristics in the evolutionary process. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Thermodynamics of natural selection III: Landauer's principle in computation and chemistry.

    Science.gov (United States)

    Smith, Eric

    2008-05-21

    This is the third in a series of three papers devoted to energy flow and entropy changes in chemical and biological processes, and their relations to the thermodynamics of computation. The previous two papers have developed reversible chemical transformations as idealizations for studying physiology and natural selection, and derived bounds from the second law of thermodynamics, between information gain in an ensemble and the chemical work required to produce it. This paper concerns the explicit mapping of chemistry to computation, and particularly the Landauer decomposition of irreversible computations, in which reversible logical operations generating no heat are separated from heat-generating erasure steps which are logically irreversible but thermodynamically reversible. The Landauer arrangement of computation is shown to produce the same entropy-flow diagram as that of the chemical Carnot cycles used in the second paper of the series to idealize physiological cycles. The specific application of computation to data compression and error-correcting encoding also makes possible a Landauer analysis of the somewhat different problem of optimal molecular recognition, which has been considered as an information theory problem. It is shown here that bounds on maximum sequence discrimination from the enthalpy of complex formation, although derived from the same logical model as the Shannon theorem for channel capacity, arise from exactly the opposite model for erasure.

  12. Tracking spore-forming bacteria in food: from natural biodiversity to selection by processes.

    Science.gov (United States)

    Postollec, Florence; Mathot, Anne-Gabrielle; Bernard, Muriel; Divanac'h, Marie-Laure; Pavan, Sonia; Sohier, Danièle

    2012-08-01

    Sporeforming bacteria are ubiquitous in the environment and exhibit a wide range of diversity leading to their natural prevalence in foodstuff. The state of the art of sporeformer prevalence in ingredients and food was investigated using a multiparametric PCR-based tool that enables simultaneous detection and identification of various genera and species mostly encountered in food, i.e., Alicyclobacillus, Anoxybacillus flavithermus, Bacillus, B. cereus group, B. licheniformis, B. pumilus, B. sporothermodurans, B. subtilis, Brevibacillus laterosporus, Clostridium, Geobacillus stearothermophilus, Moorella and Paenibacillus species. In addition, 16S rDNA sequencing was used to extend identification to other possibly present contaminants. A total of 90 food products, with or without visible trace of spoilage were analysed, i.e., 30 egg-based products, 30 milk and dairy products and 30 canned food and ingredients. Results indicated that most samples contained one or several of the targeted genera and species. For all three tested food categories, 30 to 40% of products were contaminated with both Bacillus and Clostridium. The percentage of contaminations associated with Clostridium or Bacillus represented 100% in raw materials, 72% in dehydrated ingredients and 80% in processed foods. In the last two product types, additional thermophilic contaminants were identified (A. flavithermus, Geobacillus spp., Thermoanaerobacterium spp. and Moorella spp.). These results suggest that selection, and therefore the observed (re)-emergence of unexpected sporeforming contaminants in food might be favoured by the use of given food ingredients and food processing technologies. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Thermal conditions in selected urban and semi-natural habitats, important for the forensic entomology.

    Science.gov (United States)

    Michalski, Marek; Nadolski, Jerzy

    2018-06-01

    A long-term study on thermal conditions in selected urban and semi-natural habitats, where human corpses are likely to be found, was conducted in the city of Lodz (Central Poland). Thermal data were collected during two years at nine sites and compared with corresponding data from the nearest permanent meteorological station at Lodz Airport (ICAO code: EPLL). The conditions closest to those at the meteorological station prevailed in the deciduous forest, coefficient of determination R 2 for those sets of data was above 0.96. The open field was characterized by high daily amplitudes, especially during spring, while the site in the allotment gardens was characterized by relatively high winter temperatures. The conditions prevailing in all closed space sites were very diverse and only slightly similar to the external ones. The most distinct site was an unheated basement in a tenement house, where temperature was almost always above 0°C and daily amplitudes were negligible. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. The young, the weak and the sick: evidence of natural selection by predation.

    Directory of Open Access Journals (Sweden)

    Meritxell Genovart

    2010-03-01

    Full Text Available It is assumed that predators mainly prey on substandard individuals, but even though some studies partially support this idea, evidence with large sample sizes, exhaustive analysis of prey and robust analysis is lacking. We gathered data from a culling program of yellow-legged gulls killed by two methods: by the use of raptors or by shooting at random. We compared both data sets to assess whether birds of prey killed randomly or by relying on specific individual features of the prey. We carried out a meticulous post-mortem examination of individuals, and analysing multiple prey characteristics simultaneously we show that raptors did not hunt randomly, but rather preferentially predate on juveniles, sick gulls, and individuals with poor muscle condition. Strikingly, gulls with an unusually good muscle condition were also predated more than expected, supporting the mass-dependent predation risk theory. This article provides a reliable example of how natural selection may operate in the wild and proves that predators mainly prey on substandard individuals.

  15. Increased fire frequency promotes stronger spatial genetic structure and natural selection at regional and local scales in Pinus halepensis Mill.

    Science.gov (United States)

    Budde, Katharina B; González-Martínez, Santiago C; Navascués, Miguel; Burgarella, Concetta; Mosca, Elena; Lorenzo, Zaida; Zabal-Aguirre, Mario; Vendramin, Giovanni G; Verdú, Miguel; Pausas, Juli G; Heuertz, Myriam

    2017-04-01

    The recurrence of wildfires is predicted to increase due to global climate change, resulting in severe impacts on biodiversity and ecosystem functioning. Recurrent fires can drive plant adaptation and reduce genetic diversity; however, the underlying population genetic processes have not been studied in detail. In this study, the neutral and adaptive evolutionary effects of contrasting fire regimes were examined in the keystone tree species Pinus halepensis Mill. (Aleppo pine), a fire-adapted conifer. The genetic diversity, demographic history and spatial genetic structure were assessed at local (within-population) and regional scales for populations exposed to different crown fire frequencies. Eight natural P. halepensis stands were sampled in the east of the Iberian Peninsula, five of them in a region exposed to frequent crown fires (HiFi) and three of them in an adjacent region with a low frequency of crown fires (LoFi). Samples were genotyped at nine neutral simple sequence repeats (SSRs) and at 251 single nucleotide polymorphisms (SNPs) from coding regions, some of them potentially important for fire adaptation. Fire regime had no effects on genetic diversity or demographic history. Three high-differentiation outlier SNPs were identified between HiFi and LoFi stands, suggesting fire-related selection at the regional scale. At the local scale, fine-scale spatial genetic structure (SGS) was overall weak as expected for a wind-pollinated and wind-dispersed tree species. HiFi stands displayed a stronger SGS than LoFi stands at SNPs, which probably reflected the simultaneous post-fire recruitment of co-dispersed related seeds. SNPs with exceptionally strong SGS, a proxy for microenvironmental selection, were only reliably identified under the HiFi regime. An increasing fire frequency as predicted due to global change can promote increased SGS with stronger family structures and alter natural selection in P. halepensis and in plants with similar life history traits

  16. Selective NOx Recirculation for Stationary Lean-Burn Natural Gas Engines

    Energy Technology Data Exchange (ETDEWEB)

    Nigel N. Clark

    2006-12-31

    Nitric oxide (NO) and nitrogen dioxide (NO2) generated by internal combustion (IC) engines are implicated in adverse environmental and health effects. Even though lean-burn natural gas engines have traditionally emitted lower oxides of nitrogen (NOx) emissions compared to their diesel counterparts, natural gas engines are being further challenged to reduce NOx emissions to 0.1 g/bhp-hr. The Selective NOx Recirculation (SNR) approach for NOx reduction involves cooling the engine exhaust gas and then adsorbing the NOx from the exhaust stream, followed by the periodic desorption of NOx. By sending the desorbed NOx back into the intake and through the engine, a percentage of the NOx can be decomposed during the combustion process. SNR technology has the support of the Department of Energy (DOE), under the Advanced Reciprocating Engine Systems (ARES) program to reduce NOx emissions to under 0.1 g/bhp-hr from stationary natural gas engines by 2010. The NO decomposition phenomenon was studied using two Cummins L10G natural gas fueled spark-ignited (SI) engines in three experimental campaigns. It was observed that the air/fuel ratio ({lambda}), injected NO quantity, added exhaust gas recirculation (EGR) percentage, and engine operating points affected NOx decomposition rates within the engine. Chemical kinetic model predictions using the software package CHEMKIN were performed to relate the experimental data with established rate and equilibrium models. The model was used to predict NO decomposition during lean-burn, stoichiometric burn, and slightly rich-burn cases with added EGR. NOx decomposition rates were estimated from the model to be from 35 to 42% for the lean-burn cases and from 50 to 70% for the rich-burn cases. The modeling results provided an insight as to how to maximize NOx decomposition rates for the experimental engine. Results from this experiment along with chemical kinetic modeling solutions prompted the investigation of rich-burn operating conditions

  17. Genomic insights into natural selection in the common loon (Gavia immer): evidence for aquatic adaptation.

    Science.gov (United States)

    Gayk, Zach G; Le Duc, Diana; Horn, Jeffrey; Lindsay, Alec R

    2018-04-27

    The common loon (Gavia immer) is one of five species that comprise the avian order Gaviiformes. Loons are specialized divers, reaching depths up to 60 m while staying submerged for intervals up to three minutes. In this study we used comparative genomics to investigate the genetic basis of the common loon adaptations to its ecological niche. We used Illumina short read DNA sequence data from a female bird to produce a draft assembly of the common loon (Gavia immer) genome. We identified 14,169 common loon genes, which based on well-resolved avian genomes, represent approximately 80.7% of common loon genes. Evolutionary analyses between common loon and Adelie penguin (Pygoscelis adeliae), red-throated loon (Gavia stellata), chicken (Gallus gallus), northern fulmar (Fulmarus glacialis), and rock pigeon (Columba livia) show 164 positively selected genes in common and red-throated loons. These genes were enriched for a number of protein classes, including those involved in muscle tissue development, immunoglobulin function, hemoglobin iron binding, G-protein coupled receptors, and ATP metabolism. Signatures of positive selection in these areas suggest the genus Gavia may have adapted for underwater diving by modulating their oxidative and metabolic pathways. While more research is required, these adaptations likely result in (1) compensations in oxygen respiration and energetic metabolism, (2) low-light visual acuity, and (3) elevated solute exchange. This work represents the first effort to understand the genomic adaptations of the common loon as well as other Gavia and may have implications for subsequent studies that target particular genes for loon population genetic, ecological or conservation studies.

  18. Viewing nature scenes positively affects recovery of autonomic function following acute-mental stress.

    Science.gov (United States)

    Brown, Daniel K; Barton, Jo L; Gladwell, Valerie F

    2013-06-04

    A randomized crossover study explored whether viewing different scenes prior to a stressor altered autonomic function during the recovery from the stressor. The two scenes were (a) nature (composed of trees, grass, fields) or (b) built (composed of man-made, urban scenes lacking natural characteristics) environments. Autonomic function was assessed using noninvasive techniques of heart rate variability; in particular, time domain analyses evaluated parasympathetic activity, using root-mean-square of successive differences (RMSSD). During stress, secondary cardiovascular markers (heart rate, systolic and diastolic blood pressure) showed significant increases from baseline which did not differ between the two viewing conditions. Parasympathetic activity, however, was significantly higher in recovery following the stressor in the viewing scenes of nature condition compared to viewing scenes depicting built environments (RMSSD; 50.0 ± 31.3 vs 34.8 ± 14.8 ms). Thus, viewing nature scenes prior to a stressor alters autonomic activity in the recovery period. The secondary aim was to examine autonomic function during viewing of the two scenes. Standard deviation of R-R intervals (SDRR), as change from baseline, during the first 5 min of viewing nature scenes was greater than during built scenes. Overall, this suggests that nature can elicit improvements in the recovery process following a stressor.

  19. The impacts of nature experience on human cognitive function and mental health.

    Science.gov (United States)

    Bratman, Gregory N; Hamilton, J Paul; Daily, Gretchen C

    2012-02-01

    Scholars spanning a variety of disciplines have studied the ways in which contact with natural environments may impact human well-being. We review the effects of such nature experience on human cognitive function and mental health, synthesizing work from environmental psychology, urban planning, the medical literature, and landscape aesthetics. We provide an overview of the prevailing explanatory theories of these effects, the ways in which exposure to nature has been considered, and the role that individuals' preferences for nature may play in the impact of the environment on psychological functioning. Drawing from the highly productive but disparate programs of research in this area, we conclude by proposing a system of categorization for different types of nature experience. We also outline key questions for future work, including further inquiry into which elements of the natural environment may have impacts on cognitive function and mental health; what the most effective type, duration, and frequency of contact may be; and what the possible neural mechanisms are that could be responsible for the documented effects. © 2012 New York Academy of Sciences.

  20. Cytochromes P450 for natural product biosynthesis in Streptomyces: sequence, structure, and function.

    Science.gov (United States)

    Rudolf, Jeffrey D; Chang, Chin-Yuan; Ma, Ming; Shen, Ben

    2017-08-30

    Covering: up to January 2017Cytochrome P450 enzymes (P450s) are some of the most exquisite and versatile biocatalysts found in nature. In addition to their well-known roles in steroid biosynthesis and drug metabolism in humans, P450s are key players in natural product biosynthetic pathways. Natural products, the most chemically and structurally diverse small molecules known, require an extensive collection of P450s to accept and functionalize their unique scaffolds. In this review, we survey the current catalytic landscape of P450s within the Streptomyces genus, one of the most prolific producers of natural products, and comprehensively summarize the functionally characterized P450s from Streptomyces. A sequence similarity network of >8500 P450s revealed insights into the sequence-function relationships of these oxygen-dependent metalloenzymes. Although only ∼2.4% and structurally characterized, respectively, the study of streptomycete P450s involved in the biosynthesis of natural products has revealed their diverse roles in nature, expanded their catalytic repertoire, created structural and mechanistic paradigms, and exposed their potential for biomedical and biotechnological applications. Continued study of these remarkable enzymes will undoubtedly expose their true complement of chemical and biological capabilities.

  1. Connectivity among subpopulations of Louisiana black bears as estimated by a step selection function

    Science.gov (United States)

    Clark, Joseph D.; Jared S. Laufenberg,; Maria Davidson,; Jennifer L. Murrow,

    2015-01-01

    Habitat fragmentation is a fundamental cause of population decline and increased risk of extinction for many wildlife species; animals with large home ranges and small population sizes are particularly sensitive. The Louisiana black bear (Ursus americanus luteolus) exists only in small, isolated subpopulations as a result of land clearing for agriculture, but the relative potential for inter-subpopulation movement by Louisiana black bears has not been quantified, nor have characteristics of effective travel routes between habitat fragments been identified. We placed and monitored global positioning system (GPS) radio collars on 8 female and 23 male bears located in 4 subpopulations in Louisiana, which included a reintroduced subpopulation located between 2 of the remnant subpopulations. We compared characteristics of sequential radiolocations of bears (i.e., steps) with steps that were possible but not chosen by the bears to develop step selection function models based on conditional logistic regression. The probability of a step being selected by a bear increased as the distance to natural land cover and agriculture at the end of the step decreased and as distance from roads at the end of a step increased. To characterize connectivity among subpopulations, we used the step selection models to create 4,000 hypothetical correlated random walks for each subpopulation representing potential dispersal events to estimate the proportion that intersected adjacent subpopulations (hereafter referred to as successful dispersals). Based on the models, movement paths for males intersected all adjacent subpopulations but paths for females intersected only the most proximate subpopulations. Cross-validation and genetic and independent observation data supported our findings. Our models also revealed that successful dispersals were facilitated by a reintroduced population located between 2 distant subpopulations. Successful dispersals for males were dependent on natural land

  2. Limnological aspects and trace element analysis of some selected Kenyan natural inland waters

    International Nuclear Information System (INIS)

    Ochieng, E.O.

    1987-01-01

    This thesis reports the study of trace elements, Ag, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sn, and Zn, and some limnological factors in surface water and sediments in some selected natural inland waters in Kenya. The observed levels are compared with those that are reported in literature to cause interference in biological processes in aquatic environments and human beings. There are little previous data and none that are coherent. These allow for a preliminary assessment of the significance of each element and limnological parameters in the long term stability of the environments in which they occur. XRFA and AAs have been used in the trace elements analysis and the former proved superior in the sediment (solid) samples analysis due to better accuracy and precision of less than 10%. Trace metals concentration (ppb) in the surface inland waters (rivers and lakes ) ranged as follows: Ag (1-75), Cd (2-8), Co (6-23.2), Cr (25-50), Cu (5-57.6), Mn (50-3276±450), Ni (13-34.1), Pb (7-93.6), Sn (300-500) and Zn (25-124.8). Lake sediments had the following concentration (ppm) ranges: Ag (o.098-20.58), Cd (0.188-1.345), Co (0.166-1.632), Cr (1.462-57.310), Cu (1.949-44.350), Mn (667.670-4713), Ni (11.694-56.710), Pb (10.920-192), Sn 17.210-234) and Zn (76.210-229.60). Results show that, a part from the Rift Valley saline lakes, Kenya inland water meet the WHO (1971) drinking water standards related to aquatic living environments. Concentration of some trace metals: Ag, Cd, Cu, Mn and Zn change upon raw water treatments. Preconcentration techniques have been attempted in which preconcentration by evaporation followed by lyophilization of the liquid (water) samples was found more suitable. Bioavailable (total exchangeable) metal concentrations compared very well with the concentrations in the fish muscles. Comparison with the analysis made by earlier investigators indicated a remarkable constancy over time in the chemistry of Lake Victoria and its affluent rivers. Kenyan natural

  3. The relative nature of fertilization success: Implications for the study of post-copulatory sexual selection

    Directory of Open Access Journals (Sweden)

    García-González Francisco

    2008-05-01

    Full Text Available Abstract Background The determination of genetic variation in sperm competitive ability is fundamental to distinguish between post-copulatory sexual selection models based on good-genes vs compatible genes. The sexy-sperm and the good-sperm hypotheses for the evolution of polyandry require additive (intrinsic effects of genes influencing sperm competitiveness, whereas the genetic incompatibility hypothesis invokes non-additive genetic effects. A male's sperm competitive ability is typically estimated from his fertilization success, a measure that is dependent on the ability of rival sperm competitors to fertilize the ova. It is well known that fertilization success may be conditional to genotypic interactions among males as well as between males and females. However, the consequences of effects arising from the random sampling of sperm competitors upon the estimation of genetic variance in sperm competitiveness have been overlooked. Here I perform simulations of mating trials performed in the context of sibling analysis to investigate whether the ability to detect additive genetic variance underlying the sperm competitiveness phenotype is hindered by the relative nature of fertilization success measurements. Results Fertilization success values render biased sperm competitive ability values. Furthermore, asymmetries among males in the errors committed when estimating sperm competitive abilities are likely to exist as long as males exhibit variation in sperm competitiveness. Critically, random effects arising from the relative nature of fertilization success lead to an underestimation of underlying additive genetic variance in sperm competitive ability. Conclusion The results show that, regardless of the existence of genotypic interactions affecting the output of sperm competition, fertilization success is not a perfect predictor of sperm competitive ability because of the stochasticity of the background used to obtain fertilization success

  4. Gross Motor Function Measure Evolution Ratio: Use as a Control for Natural Progression in Cerebral Palsy.

    Science.gov (United States)

    Marois, Pierre; Marois, Mikael; Pouliot-Laforte, Annie; Vanasse, Michel; Lambert, Jean; Ballaz, Laurent

    2016-05-01

    To develop a new way to interpret Gross Motor Function Measure (GMFM-66) score improvement in studies conducted without control groups in children with cerebral palsy (CP). The curves, which describe the pattern of motor development according to the children's Gross Motor Function Classification System level, were used as historical control to define the GMFM-66 expected natural evolution in children with CP. These curves have been modeled and generalized to fit the curve to particular children characteristics. Research center. Not applicable. Not applicable. Not applicable. Assuming that the GMFM-66 score evolution followed the shape of the Rosenbaum curves, by taking into account the age and GMFM-66 score of children, the expected natural evolution of the GMFM-66 score was predicted for any group of children with CP who were Ratio, was defined as follows: Gross Motor Function Measure Evolution Ratio=measured GMFM-66 score change/expected natural evolution. For practical or ethical reasons, it is almost impossible to use control groups in studies evaluating effectiveness of many therapeutic modalities. The Gross Motor Function Measure Evolution Ratio gives the opportunity to take into account the expected natural evolution of the gross motor function of children with CP, which is essential to accurately interpret the therapy effect on the GMFM-66. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  5. Evolución por selección natural: más evidencias que nunca Evolution by natural selection: more evidence than ever before

    Directory of Open Access Journals (Sweden)

    ROBERTO F. NESPOLO

    2003-12-01

    Full Text Available La teoría moderna de la evolución, entendida como la integración del conocimiento teórico y empírico de la evolución orgánica, desarrollado desde Darwin hasta ahora, es uno de los cuerpos conceptuales más importantes en biología. Sin embargo, cierto debate ha surgido en el medio científico local en torno a la validez de la selección natural como mecanismo explicativo de la evolución adaptativa. Este artículo revisa las evidencias recientes sobre el rol de la selección natural en poblaciones naturales y artificiales. Además, se presentan algunas herramientas conceptuales básicas necesarias para el estudio de la microevolución a escala ecológica, las que se discuten a la luz de la información mostrada desde un punto de vista cuantitativo. El resultado es claro: la selección natural puede ser, está siendo y ha sido medida y demostrada en el campo y en el laboratorio, no muchas, sino cientos de veces durante las últimas décadas. El estudio de la evolución por selección natural ha alcanzado una fase de madurez que es demostrada por la aparición de varias síntesis y metaanálisis así como también por el comienzo de "aplicaciones evolutivas", donde la evolución por selección natural es utilizada para resolver problemas prácticos en disciplinas diferentes a la biologia básica. Se concluye que se necesita cautela cuando se cuestiona la teoría evolutiva. La gran cantidad de evidencia disponible exige un esfuerzo serio por leer y analizar dicho conocimiento antes de criticar sus fundamentos teóricosThe modern evolutionary theory, understood as the integration of the empirically-demonstrated theoretical foundations of organic evolution, is one of the most pervasive conceptual frameworks in biology. However, some debate has arisen in the Chilean scientific community regarding the legitimacy of natural selection as a mechanism that explains adaptive evolution. This review surveys the recent evidence for natural selection and

  6. Ion-selective electrodes in organic elemental and functional group analysis: a review

    International Nuclear Information System (INIS)

    Selig, W.

    1977-01-01

    The literature on the use of ion-selective electrodes in organic elemental and functional group analysis is surveyed in some detail. The survey is complete through Chemical Abstracts, Vol. 83 (1975). 40 figures, 52 tables, 236 references

  7. Ion-selective electrodes in organic elemental and functional group analysis: a review

    Energy Technology Data Exchange (ETDEWEB)

    Selig, W.

    1977-11-08

    The literature on the use of ion-selective electrodes in organic elemental and functional group analysis is surveyed in some detail. The survey is complete through Chemical Abstracts, Vol. 83 (1975). 40 figures, 52 tables, 236 references.

  8. Spacer for enhancing selectivity of functionalized polymer towards Pu(IV)

    International Nuclear Information System (INIS)

    Chavan, Vivek; Pandey, A.K.; Goswami, A.

    2012-01-01

    To address problems in selective and fast preconcentration of Pu(IV) at ultratrace concentration from the multicomponents aqueous media and low level nuclear waste, a new functionalized polymer sorbent was developed

  9. At what time is the cocktail party? A late locus of selective attention to natural speech.

    Science.gov (United States)

    Power, Alan J; Foxe, John J; Forde, Emma-Jane; Reilly, Richard B; Lalor, Edmund C

    2012-05-01

    Distinguishing between speakers and focusing attention on one speaker in multi-speaker environments is extremely important in everyday life. Exactly how the brain accomplishes this feat and, in particular, the precise temporal dynamics of this attentional deployment are as yet unknown. A long history of behavioral research using dichotic listening paradigms has debated whether selective attention to speech operates at an early stage of processing based on the physical characteristics of the stimulus or at a later stage during semantic processing. With its poor temporal resolution fMRI has contributed little to the debate, while EEG-ERP paradigms have been hampered by the need to average the EEG in response to discrete stimuli which are superimposed onto ongoing speech. This presents a number of problems, foremost among which is that early attention effects in the form of endogenously generated potentials can be so temporally broad as to mask later attention effects based on the higher level processing of the speech stream. Here we overcome this issue by utilizing the AESPA (auditory evoked spread spectrum analysis) method which allows us to extract temporally detailed responses to two concurrently presented speech streams in natural cocktail-party-like attentional conditions without the need for superimposed probes. We show attentional effects on exogenous stimulus processing in the 200-220 ms range in the left hemisphere. We discuss these effects within the context of research on auditory scene analysis and in terms of a flexible locus of attention that can be deployed at a particular processing stage depending on the task. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  10. Anthropogenic impacts on an oyster metapopulation: Pathogen introduction, climate change and responses to natural selection

    Directory of Open Access Journals (Sweden)

    David Bushek

    2016-08-01

    Full Text Available Abstract Humans rely on marine ecosystems for a variety of services but often impact these ecosystems directly or indirectly limiting their capacity to provide such services. One growing impact is the emergence of marine disease. We present results from a unique case study examining how oysters, a dominant organism in many coastal bays and estuaries that is often harvested for food, have responded to pathogens influenced by human activities, namely the introduction of novel pathogens. Climate change has enabled a northward spread and establishment of Dermo disease in oysters along the eastern seaboard of North America and human activities inadvertently introduced MSX disease along this same coast. Oysters in Delaware Bay have responded differently to each pathogen, and uniquely to MSX disease by developing a highly resistant baywide population not documented in any other bay. Offspring were produced using parents collected from low or high disease (MSX and Dermo regions of Delaware Bay and exposed in a common garden experiment along with a naïve population from Maine. Results indicated widespread resistance to MSX disease, but not to Dermo disease, across Delaware Bay. One striking result was the demonstration of resilience in the population through its capacity to spread, presumably through larval transport, resistance to MSX disease into portions of the population that have experienced little to no MSX disease pressure themselves. Related studies indicated that larval transport mechanisms allowed widespread dispersal such that the entire metapopulation could acquire a high level of resistance over time if disease resistance is sufficiently heritable. The findings have implications for restoration, management and recovery of diseased populations. Namely, that if left to their own devices, natural selection may find a solution that enables populations to recover from introduced pathogens.

  11. Strong Signature of Natural Selection within an FHIT Intron Implicated in Prostate Cancer Risk

    Science.gov (United States)

    Ding, Yan; Larson, Garrett; Rivas, Guillermo; Lundberg, Cathryn; Geller, Louis; Ouyang, Ching; Weitzel, Jeffrey; Archambeau, John; Slater, Jerry; Daly, Mary B.; Benson, Al B.; Kirkwood, John M.; O'Dwyer, Peter J.; Sutphen, Rebecca; Stewart, James A.; Johnson, David; Nordborg, Magnus; Krontiris, Theodore G.

    2008-01-01

    Previously, a candidate gene linkage approach on brother pairs affected with prostate cancer identified a locus of prostate cancer susceptibility at D3S1234 within the fragile histidine triad gene (FHIT), a tumor suppressor that induces apoptosis. Subsequent association tests on 16 SNPs spanning approximately 381 kb surrounding D3S1234 in Americans of European descent revealed significant evidence of association for a single SNP within intron 5 of FHIT. In the current study, re-sequencing and genotyping within a 28.5 kb region surrounding this SNP further delineated the association with prostate cancer risk to a 15 kb region. Multiple SNPs in sequences under evolutionary constraint within intron 5 of FHIT defined several related haplotypes with an increased risk of prostate cancer in European-Americans. Strong associations were detected for a risk haplotype defined by SNPs 138543, 142413, and 152494 in all cases (Pearson's χ2 = 12.34, df 1, P = 0.00045) and for the homozygous risk haplotype defined by SNPs 144716, 142413, and 148444 in cases that shared 2 alleles identical by descent with their affected brothers (Pearson's χ2 = 11.50, df 1, P = 0.00070). In addition to highly conserved sequences encompassing SNPs 148444 and 152413, population studies revealed strong signatures of natural selection for a 1 kb window covering the SNP 144716 in two human populations, the European American (π = 0.0072, Tajima's D = 3.31, 14 SNPs) and the Japanese (π = 0.0049, Fay & Wu's H = 8.05, 14 SNPs), as well as in chimpanzees (Fay & Wu's H = 8.62, 12 SNPs). These results strongly support the involvement of the FHIT intronic region in an increased risk of prostate cancer. PMID:18953408

  12. Nonlinear selection and a blend of convergent, divergent and parallel evolution shapes natural variation in glucosinolates

    DEFF Research Database (Denmark)

    Kliebenstein, Daniel James; Cacho, N. Ivalú

    2016-01-01

    and traits that is highly similar both within and between species. Further, early field trials with single gene recreations of natural variation are showing that selection is highly fluctuating both from site to site and from year to year within a location. This review goes into the specific ecological......The molecular mechanisms underlying organismal fitness in complex environments is just beginning to be illuminated. One of the pre-eminent model systems that span the molecular to field fitness chasm is the natural variation in glucosinolate defence metabolites within the Capparales. In this system......, evolutionary and molecular observations for each of the major loci controlling natural variation in glucosinolates....

  13. Natural selection in avian protein-coding genes expressed in brain.

    Science.gov (United States)

    Axelsson, Erik; Hultin-Rosenberg, Lina; Brandström, Mikael; Zwahlén, Martin; Clayton, David F; Ellegren, Hans

    2008-06-01

    The evolution of birds from theropod dinosaurs took place approximately 150 million years ago, and was associated with a number of specific adaptations that are still evident among extant birds, including feathers, song and extravagant secondary sexual characteristics. Knowledge about the molecular evolutionary background to such adaptations is lacking. Here, we analyse the evolution of > 5000 protein-coding gene sequences expressed in zebra finch brain by comparison to orthologous sequences in chicken. Mean d(N)/d(S) is 0.085 and genes with their maximal expression in the eye and central nervous system have the lowest mean d(N)/d(S) value, while those expressed in digestive and reproductive tissues exhibit the highest. We find that fast-evolving genes (those which have higher than expected rate of nonsynonymous substitution, indicative of adaptive evolution) are enriched for biological functions such as fertilization, muscle contraction, defence response, response to stress, wounding and endogenous stimulus, and cell death. After alignment to mammalian orthologues, we identify a catalogue of 228 genes that show a significantly higher rate of protein evolution in the two bird lineages than in mammals. These accelerated bird genes, representing candidates for avian-specific adaptations, include genes implicated in vocal learning and other cognitive processes. Moreover, colouration genes evolve faster in birds than in mammals, which may have been driven by sexual selection for extravagant plumage characteristics.

  14. Therapeutic potential of functional selectivity in the treatment of heart failure

    DEFF Research Database (Denmark)

    Christensen, Gitte Lund; Aplin, Mark; Hansen, Jakob Lerche

    2010-01-01

    Adrenergic and angiotensin receptors are prominent targets in pharmacological alleviation of cardiac remodeling and heart failure, but their use is associated with cardiodepressant side effects. Recent advances in our understanding of seven transmembrane receptor signaling show that it is possible...... to design ligands with "functional selectivity," acting as agonists on certain signaling pathways while antagonizing others. This represents a major pharmaceutical opportunity to separate desired from adverse effects governed by the same receptor. Accordingly, functionally selective ligands are currently...

  15. Designer's approach for scene selection in tests of preference and restoration along a continuum of natural to manmade environments

    Science.gov (United States)

    Hunter, MaryCarol R.; Askarinejad, Ali

    2015-01-01

    It is well-established that the experience of nature produces an array of positive benefits to mental well-being. Much less is known about the specific attributes of green space which produce these effects. In the absence of translational research that links theory with application, it is challenging to design urban green space for its greatest restorative potential. This translational research provides a method for identifying which specific physical attributes of an environmental setting are most likely to influence preference and restoration responses. Attribute identification was based on a triangulation process invoking environmental psychology and aesthetics theories, principles of design founded in mathematics and aesthetics, and empirical research on the role of specific physical attributes of the environment in preference or restoration responses. From this integration emerged a list of physical attributes defining aspects of spatial structure and environmental content found to be most relevant to the perceptions involved with preference and restoration. The physical attribute list offers a starting point for deciphering which scene stimuli dominate or collaborate in preference and restoration responses. To support this, functional definitions and metrics—efficient methods for attribute quantification are presented. Use of these research products and the process for defining place-based metrics can provide (a) greater control in the selection and interpretation of the scenes/images used in tests of preference and restoration and (b) an expanded evidence base for well-being designers of the built environment. PMID:26347691

  16. Chinese Function Manager of 2006 Partenariat Comments on the Selection Principle for Chinese Enterprises

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Fang Lei, EU-China Partenariat 2006Function Manager for Chinese Host Companies, worked together with Mr. Richard Morgan, EU Project Expert,Mr. Han Meiqing, Chinese Project Expert in the primary selection of Chinese enterprises.In reply to the strong request of the relevant governmental institutions, CCPIT and enterprises, he gave the following introductions about the details of selection.

  17. Understanding Linear Function: A Comparison of Selected Textbooks from England and Shanghai

    Science.gov (United States)

    Wang, Yuqian; Barmby, Patrick; Bolden, David

    2017-01-01

    This study describes a comparison of how worked examples in selected textbooks from England and Shanghai presented possible learning trajectories towards understanding linear function. Six selected English textbooks and one Shanghai compulsory textbook were analysed with regards to the understanding required for pure mathematics knowledge in…

  18. Self-organization and natural selection in the evolution of complex despotic societies

    NARCIS (Netherlands)

    Hemelrijk, C.K.

    2002-01-01

    Differences between related species are usually explained as separate adaptations produced by individual selection. I discuss in this paper how related species, which differ in many respects, may evolve by a combination of individual selection, self-organization, and group-selection, requiring an

  19. Functional Reconstitution of a Fungal Natural Product Gene Cluster by Advanced Genome Editing.

    Science.gov (United States)

    Weber, Jakob; Valiante, Vito; Nødvig, Christina S; Mattern, Derek J; Slotkowski, Rebecca A; Mortensen, Uffe H; Brakhage, Axel A

    2017-01-20

    Filamentous fungi produce varieties of natural products even in a strain dependent manner. However, the genetic basis of chemical speciation between strains is still widely unknown. One example is trypacidin, a natural product of the opportunistic human pathogen Aspergillus fumigatus, which is not produced among different isolates. Combining computational analysis with targeted gene editing, we could link a single nucleotide insertion in the polyketide synthase of the trypacidin biosynthetic pathway and reconstitute its production in a nonproducing strain. Thus, we present a CRISPR/Cas9-based tool for advanced molecular genetic studies in filamentous fungi, exploiting selectable markers separated from the edited locus.

  20. Genome patterns of selection and introgression of haplotypes in natural populations of the house mouse (Mus musculus.

    Directory of Open Access Journals (Sweden)

    Fabian Staubach

    Full Text Available General parameters of selection, such as the frequency and strength of positive selection in natural populations or the role of introgression, are still insufficiently understood. The house mouse (Mus musculus is a particularly well-suited model system to approach such questions, since it has a defined history of splits into subspecies and populations and since extensive genome information is available. We have used high-density single-nucleotide polymorphism (SNP typing arrays to assess genomic patterns of positive selection and introgression of alleles in two natural populations of each of the subspecies M. m. domesticus and M. m. musculus. Applying different statistical procedures, we find a large number of regions subject to apparent selective sweeps, indicating frequent positive selection on rare alleles or novel mutations. Genes in the regions include well-studied imprinted loci (e.g. Plagl1/Zac1, homologues of human genes involved in adaptations (e.g. alpha-amylase genes or in genetic diseases (e.g. Huntingtin and Parkin. Haplotype matching between the two subspecies reveals a large number of haplotypes that show patterns of introgression from specific populations of the respective other subspecies, with at least 10% of the genome being affected by partial or full introgression. Using neutral simulations for comparison, we find that the size and the fraction of introgressed haplotypes are not compatible with a pure migration or incomplete lineage sorting model. Hence, it appears that introgressed haplotypes can rise in frequency due to positive selection and thus can contribute to the adaptive genomic landscape of natural populations. Our data support the notion that natural genomes are subject to complex adaptive processes, including the introgression of haplotypes from other differentiated populations or species at a larger scale than previously assumed for animals. This implies that some of the admixture found in inbred strains of mice

  1. Warning signal brightness variation: sexual selection may work under the radar of natural selection in populations of a polytypic poison frog.

    Science.gov (United States)

    Crothers, Laura R; Cummings, Molly E

    2013-05-01

    Though theory predicts consistency of warning signals in aposematic species to facilitate predator learning, variation in these signals often occurs in nature. The strawberry poison frog Dendrobates pumilio is an exceptionally polytypic (populations are phenotypically distinct) aposematic frog exhibiting variation in warning color and brightness. In the Solarte population, males and females both respond differentially to male brightness variation. Here, we demonstrate through spectrophotometry and visual modeling that aposematic brightness variation within this population is likely visible to two putative predators (crabs, snakes) and conspecifics but not to the presumed major predator (birds). This study thus suggests that signal brightness within D. pumilio populations can be shaped by sexual selection, with limited opportunity for natural selection to influence this trait due to predator sensory constraints. Because signal brightness changes can ultimately lead to changes in hue, our findings at the within-population level can provide insights into understanding this polytypism at across-population scales.

  2. Analysis of a Moodle-Based Training Program about the Pedagogical Content Knowledge of Evolution Theory and Natural Selection

    Science.gov (United States)

    Stasinakis, Panagiotis K.; Kalogiannnakis, Michail

    2017-01-01

    In this study we aim to find out whether a training program for secondary school science teachers which was organized based on the model of Pedagogical Content Knowledge (PCK), could improve their individual PCK for a specific scientific issue. The Evolution Theory (ET) and the Natural Selection (NS) were chosen as the scientific issues of…

  3. Young Children's Near and Far Transfer of the Basic Theory of Natural Selection: An Analogical Storybook Intervention

    Science.gov (United States)

    Emmons, Natalie; Lees, Kristin; Kelemen, Deborah

    2018-01-01

    Misconceptions about adaptation by natural selection are widespread among adults and likely stem, in part, from cognitive biases and intuitive theories observable in early childhood. Current educational guidelines that recommend delaying comprehensive instruction on the topic of adaptation until adolescence, therefore, raise concerns because…

  4. Design and optimisation of organic Rankine cycles for waste heat recovery in marine applications using the principles of natural selection

    DEFF Research Database (Denmark)

    Larsen, Ulrik; Pierobon, Leonardo; Haglind, Fredrik

    2013-01-01

    , boundary conditions, hazard levels and environmental concerns. A generally applicable methodology, based on the principles of natural selection, is presented and used to determine the optimum working fluid, boiler pressure and Rankine cycle process layout for scenarios related to marine engine heat...

  5. Implications of the difference between true and predicted breeding values for the study of natural selection and micro-evolution

    NARCIS (Netherlands)

    Postma, E.

    2006-01-01

    The ability to predict individual breeding values in natural populations with known pedigrees has provided a powerful tool to separate phenotypic values into their genetic and environmental components in a nonexperimental setting. This has allowed sophisticated analyses of selection, as well as

  6. Selective grazing by adults and larvae of the zebra mussel (Dreissena polymorpha): application of flow cytometry to natural seston

    NARCIS (Netherlands)

    Pires, L.M.D.; Jonker, R.M.; Van Donk, E.; Laanbroek, H.J.

    2004-01-01

    1. Selective grazing of adults and larvae of the zebra mussel (Dreissena polymorpha) on phytoplankton and detritus from both laboratory cultures and natural seston was quantified using flow cytometry. 2. Mean clearance rate of adult zebra mussels was higher on a mixture of the green alga Scenedesmus

  7. Selective grazing by adults and larvae of the zebra mussel (Dreissena polymorpha): application of flow cytometry to natural seston

    NARCIS (Netherlands)

    Dionisio Pires, L.M.; Jonker, R.R.; Donk, E.van; Laanbroek, H.J.

    2004-01-01

    1. Selective grazing of adults and larvae of the zebra mussel (Dreissena polymorpha) on phytoplankton and detritus from both laboratory cultures and natural seston was quantified using flow cytometry. 2. Mean clearance rate of adult zebra mussels was higher on a mixture of the green

  8. Darwin vs. Wallace: When Poetry Dies and When Poetry Survives in the Not-so-Natural Selection of Memetic Evolution

    Science.gov (United States)

    Christensen, Bryce

    2011-01-01

    The theory of memetic evolution--explaining the reproduction of cultural units called "memes"--illuminates the decline of poetry as a cultural presence by clarifying the contrasting attitudes towards poetry manifested by the co-discoverers of natural selection: Charles Darwin and Alfred Wallace. Darwin's eventual indifference to poetry…

  9. Technical functions : a drawbridge between the intentional and structural nature of technical artefacts

    NARCIS (Netherlands)

    Vermaas, P.E.; Houkes, W.N.

    2006-01-01

    In this paper we present an action-theoretic account of artefact using and designing and describe our ICE-theory of function ascriptions to technical artefacts. By means of this account and theory we analyse the thesis of the dual nature of technical artefacts according to which descriptions of

  10. Evaluating natural resource amenities in a human life expectancy production function

    Science.gov (United States)

    Neelam C. Poudyal; Donald G. Hodges; J.M. Bowker; H.K. Cordell

    2009-01-01

    This study examined the effect of natural resource amenities on human life expectancy. Extending theexisting model of the life expectancy production function, and correcting for spatial dependence, weevaluated the determinants of life expectancy using county level data. Results indicate that after controlling

  11. Accounting for animal movement in estimation of resource selection functions: sampling and data analysis.

    Science.gov (United States)

    Forester, James D; Im, Hae Kyung; Rathouz, Paul J

    2009-12-01

    Patterns of resource selection by animal populations emerge as a result of the behavior of many individuals. Statistical models that describe these population-level patterns of habitat use can miss important interactions between individual animals and characteristics of their local environment; however, identifying these interactions is difficult. One approach to this problem is to incorporate models of individual movement into resource selection models. To do this, we propose a model for step selection functions (SSF) that is composed of a resource-independent movement kernel and a resource selection function (RSF). We show that standard case-control logistic regression may be used to fit the SSF; however, the sampling scheme used to generate control points (i.e., the definition of availability) must be accommodated. We used three sampling schemes to analyze simulated movement data and found that ignoring sampling and the resource-independent movement kernel yielded biased estimates of selection. The level of bias depended on the method used to generate control locations, the strength of selection, and the spatial scale of the resource map. Using empirical or parametric methods to sample control locations produced biased estimates under stronger selection; however, we show that the addition of a distance function to the analysis substantially reduced that bias. Assuming a uniform availability within a fixed buffer yielded strongly biased selection estimates that could be corrected by including the distance function but remained inefficient relative to the empirical and parametric sampling methods. As a case study, we used location data collected from elk in Yellowstone National Park, USA, to show that selection and bias may be temporally variable. Because under constant selection the amount of bias depends on the scale at which a resource is distributed in the landscape, we suggest that distance always be included as a covariate in SSF analyses. This approach to

  12. Functionalization of biomass carbonaceous aerogels: selective preparation of MnO2@CA composites for supercapacitors.

    Science.gov (United States)

    Ren, Yumei; Xu, Qun; Zhang, Jianmin; Yang, Hongxia; Wang, Bo; Yang, Daoyuan; Hu, Junhua; Liu, Zhimin

    2014-06-25

    Functionalized porous carbon materials with hierarchical structure and developed porosity coming from natural and renewable biomass have been attracting tremendous attention recently. In this work, we present a facile and scalable method to synthesize MnO2 loaded carbonaceous aerogel (MnO2@CA) composites via the hydrothermal carbonaceous (HTC) process. We employ two reaction systems of the mixed metal ion precursors to study the optimal selective adsorption and further reaction of MnO2 precursor on CA. Our experimental results show that the system containing KMnO4 and Na2S2O3·5H2O exhibits better electrochemical properties compared with the reaction system of MnSO4·H2O and (NH4)2S2O8. For the former, the obtained MnO2@CA displays the specific capacitance of 123.5 F·g(-1). The enhanced supercapacitance of MnO2@CA nanocomposites could be ascribed to both electrochemical contributions of the loaded MnO2 nanoparticles and the porous structure of three-dimensional carbonaceous aerogels. This study not only indicates that it is vital for the reaction systems to match with porous carbonaceous materials, but also offers a new fabrication strategy to prepare lightweight and high-performance materials that can be used in energy storage devices.

  13. Using Multiple Lenses to Examine the Development of Beginning Biology Teachers' Pedagogical Content Knowledge for Teaching Natural Selection Simulations

    Science.gov (United States)

    Sickel, Aaron J.; Friedrichsen, Patricia

    2018-02-01

    Pedagogical content knowledge (PCK) has become a useful construct to examine science teacher learning. Yet, researchers conceptualize PCK development in different ways. The purpose of this longitudinal study was to use three analytic lenses to understand the development of three beginning biology teachers' PCK for teaching natural selection simulations. We observed three early-career biology teachers as they taught natural selection in their respective school contexts over two consecutive years. Data consisted of six interviews with each participant. Using the PCK model developed by Magnusson et al. (1999), we examined topic-specific PCK development utilizing three different lenses: (1) expansion of knowledge within an individual knowledge base, (2) integration of knowledge across knowledge bases, and (3) knowledge that explicitly addressed core concepts of natural selection. We found commonalities across the participants, yet each lens was also useful to understand the influence of different factors (e.g., orientation, subject matter preparation, and the idiosyncratic nature of teacher knowledge) on PCK development. This multi-angle approach provides implications for considering the quality of beginning science teachers' knowledge and future research on PCK development. We conclude with an argument that explicitly communicating lenses used to understand PCK development will help the research community compare analytic approaches and better understand the nature of science teacher learning.

  14. Selective removal of lanthanides from natural waters, acidic streams and dialysate

    Energy Technology Data Exchange (ETDEWEB)

    Yantasee, Wassana, E-mail: wassana.yantasee@pnl.gov [Pacific Northwest National Laboratory (PNNL), P.O. Box 999, Richland, WA 99352 (United States); Fryxell, Glen E.; Addleman, R. Shane; Wiacek, Robert J.; Koonsiripaiboon, View; Pattamakomsan, Kanda; Sukwarotwat, Vichaya [Pacific Northwest National Laboratory (PNNL), P.O. Box 999, Richland, WA 99352 (United States); Xu Jide; Raymond, Kenneth N. [Chemistry Department, University of California, Berkeley, CA 94720 (United States); LBNL, Berkeley, CA 94720 (United States)

    2009-09-15

    The increased demand for the lanthanides in commercial products result in increased production of lanthanide containing ores, which increases public exposure to the lanthanides, both from various commercial products and from production wastes/effluents. This work investigates lanthanide (La, Ce, Pr, Nd, Eu, Gd and Lu) binding properties of self-assembled monolayers on mesoporous silica supports (SAMMS{sup TM}), that were functionalized with diphosphonic acid (DiPhos), acetamide phosphonic acid (AcPhos), propionamide phosphonic acid (Prop-Phos), and 1-hydroxy-2-pyridinone (1,2-HOPO), from natural waters (river, ground and sea waters), acid solutions (to mimic certain industrial process streams), and dialysate. The affinity, capacity, and kinetics of the lanthanide sorption, as well as regenerability of SAMMS materials were investigated. Going from the acid side over to the alkaline side, the AcPhos- and DiPhos-SAMMS maintain their outstanding affinity for lanthanides, which enable the use of the materials in the systems where the pH may fluctuate. In acid solutions, Prop-Phos- and 1,2-HOPO-SAMMS have differing affinity along the lanthanide series, suggesting their use in chromatographic lanthanide separation. Over 95% of 100 {mu}g/L of Gd in dialysate was removed by the Prop-Phos-SAMMS after 1 min and 99% over 10 min. SAMMS can be regenerated with an acid wash (0.5 M HCl) without losing the binding properties. Thus, they have a great potential to be used as in large-scale treatment of lanthanides, lanthanide separation prior to analytical instruments, and in sorbent dialyzers for treatment of acute lanthanide poisoning.

  15. Selective cell response on natural polymer bio-interfaces textured by femtosecond laser

    Science.gov (United States)

    Daskalova, A.; Trifonov, A.; Bliznakova, I.; Nathala, C.; Ajami, A.; Husinsky, W.; Declercq, H.; Buchvarov, I.

    2018-02-01

    This study reports on the evaluation of laser processed natural polymer-chitosan, which is under consideration as a biointerface used for temporary applications as skin and cartilage substitutes. It is employed for tissue engineering purposes, since it possesses a significant degree of biocompatibility and biodegradability. Chitosan-based thin films were processed by femtosecond laser radiation to enhance the surface properties of the material. Various geometry patterns were produced on polymer surfaces and employed to examine cellular adhesion and orientation. The topography of the modified zones was observed using scanning electron microscopy and confocal microscopy. Test of the material cytotoxicity was performed by evaluating the life/dead cell correlation. The obtained results showed that texturing with femtosecond laser pulses is appropriate method to initiate a predefined cellular response. Formation of surface modifications in the form of foams with an expansion of the material was created under laser irradiation with a number of applied laser pulses from N = 1-5. It is shown that irradiation with N > 5 results in disturbance of microfoam. Material characterization reveals a decrease in water contact angle values after laser irradiation of chitosan films. Consequently, changes in surface roughness of chitosan thin-film surface result in its functionalization. Cultivation of MC3T3 and ATMSC cells show cell orientational migration concerning different surface patterning. The influence of various pulse durations (varying from τ = 30-500 fs) over biofilms surface was examined regarding the evolution of surface morphology. The goal of this study was to define the optimal laser conditions (laser energy, number of applied pulses, and pulse duration) to alter surface wettability properties and porosity to improve material performance. The acquired set of results indicate the way to tune the surface properties to optimize cell-interface interaction.

  16. Selective removal of lanthanides from natural waters, acidic streams and dialysate

    International Nuclear Information System (INIS)

    Yantasee, Wassana; Fryxell, Glen E.; Addleman, R. Shane; Wiacek, Robert J.; Koonsiripaiboon, View; Pattamakomsan, Kanda; Sukwarotwat, Vichaya; Xu Jide; Raymond, Kenneth N.

    2009-01-01

    The increased demand for the lanthanides in commercial products result in increased production of lanthanide containing ores, which increases public exposure to the lanthanides, both from various commercial products and from production wastes/effluents. This work investigates lanthanide (La, Ce, Pr, Nd, Eu, Gd and Lu) binding properties of self-assembled monolayers on mesoporous silica supports (SAMMS TM ), that were functionalized with diphosphonic acid (DiPhos), acetamide phosphonic acid (AcPhos), propionamide phosphonic acid (Prop-Phos), and 1-hydroxy-2-pyridinone (1,2-HOPO), from natural waters (river, ground and sea waters), acid solutions (to mimic certain industrial process streams), and dialysate. The affinity, capacity, and kinetics of the lanthanide sorption, as well as regenerability of SAMMS materials were investigated. Going from the acid side over to the alkaline side, the AcPhos- and DiPhos-SAMMS maintain their outstanding affinity for lanthanides, which enable the use of the materials in the systems where the pH may fluctuate. In acid solutions, Prop-Phos- and 1,2-HOPO-SAMMS have differing affinity along the lanthanide series, suggesting their use in chromatographic lanthanide separation. Over 95% of 100 μg/L of Gd in dialysate was removed by the Prop-Phos-SAMMS after 1 min and 99% over 10 min. SAMMS can be regenerated with an acid wash (0.5 M HCl) without losing the binding properties. Thus, they have a great potential to be used as in large-scale treatment of lanthanides, lanthanide separation prior to analytical instruments, and in sorbent dialyzers for treatment of acute lanthanide poisoning.

  17. Systemic functional grammar in natural language generation linguistic description and computational representation

    CERN Document Server

    Teich, Elke

    1999-01-01

    This volume deals with the computational application of systemic functional grammar (SFG) for natural language generation. In particular, it describes the implementation of a fragment of the grammar of German in the computational framework of KOMET-PENMAN for multilingual generation. The text also presents a specification of explicit well-formedness constraints on syntagmatic structure which are defined in the form of typed feature structures. It thus achieves a model of systemic functional grammar that unites both the strengths of systemics, such as stratification, functional diversification

  18. Home Range Characteristics and Habitat Selection by Daurian Hedgehogs ( Mesechinus dauuricus in Ikh Nart Nature Reserve, Mongolia

    Directory of Open Access Journals (Sweden)

    Mirka Zapletal

    2012-12-01

    Full Text Available We examined home range characteristics and habitat selection of Daurian hedgehogs in Ikh Nart Nature Reserve, Mongolia. Home ranges of hedgehogs varied from 113.15 ha to 2,171.97 ha, and were larger in early summer than late summer. Hedgehogs showed relative preference for rocky outcrops and low-density shrub habitats, and relative avoidance of high- density shrub areas. Habitat selection also changed between early and late summer, shifting to greater use of low-density shrub areas and decreased use of forb-dominated short grass. Our baseline data on home ranges and habitat selection expand understanding of hedgehog ecology and provide guidance for future management decisions in Ikh Nart Nature Reserve and elsewhere in Mongolia.

  19. Method of selective dissolution for characterization of particulate forms of radium and barium in natural and waste waters

    International Nuclear Information System (INIS)

    Benes, P.; Sedlacek, J.; Sebesta, F.; Sandrik, R.

    1981-01-01

    A new method is proposed for characterization of particulate forms of radium and barium in natural and waste waters. Particulate solids suspended in 1-3 l. of water are first concentrated by membrane filtration or by centrifugation to 20-50 ml of a concentrate which is then filtered through a small-size membrane filter. The solids retained by the filter are successively washed with three selective solvents releasing ''loosely bound'', ''acid soluble'' and ''barium sulfate'' forms of radium and barium. Compositions and volumes of the selective solvents have been chosen using model experiments and partially checked by analysis of natural samples. Radium and barium ''in crystalline detritus'' remain on the filter and are determined after an acid digestion of the filter. The principal criteria and selectivity of the method are discussed. (author)

  20. Natural emulsifiers - Biosurfactants, phospholipids, biopolymers, and colloidal particles: Molecular and physicochemical basis of functional performance.

    Science.gov (United States)

    McClements, David Julian; Gumus, Cansu Ekin

    2016-08-01

    There is increasing consumer pressure for commercial products that are more natural, sustainable, and environmentally friendly, including foods, cosmetics, detergents, and personal care products. Industry has responded by trying to identify natural alternatives to synthetic functional ingredients within these products. The focus of this review article is on the replacement of synthetic surfactants with natural emulsifiers, such as amphiphilic proteins, polysaccharides, biosurfactants, phospholipids, and bioparticles. In particular, the physicochemical basis of emulsion formation and stabilization by natural emulsifiers is discussed, and the benefits and limitations of different natural emulsifiers are compared. Surface-active polysaccharides typically have to be used at relatively high levels to produce small droplets, but the droplets formed are highly resistant to environmental changes. Conversely, surface-active proteins are typically utilized at low levels, but the droplets formed are highly sensitive to changes in pH, ionic strength, and temperature. Certain phospholipids are capable of producing small oil droplets during homogenization, but again the droplets formed are highly sensitive to changes in environmental conditions. Biosurfactants (saponins) can be utilized at low levels to form fine oil droplets that remain stable over a range of environmental conditions. Some nature-derived nanoparticles (e.g., cellulose, chitosan, and starch) are effective at stabilizing emulsions containing relatively large oil droplets. Future research is encouraged to identify, isolate, purify, and characterize new types of natural emulsifier, and to test their efficacy in food, cosmetic, detergent, personal care, and other products. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Signatures of natural selection among lineages and habitats in Oncorhynchus mykiss

    DEFF Research Database (Denmark)

    Limborg, Morten; Blankenship, S.; Young, S.

    2012-01-01

    lineage. Overall patterns of variation affirmed clear distinctions between lineages and in most instances, isolation by distance within them. Evidence for divergent selection at eight candidate loci included significant landscape correlations, particularly with temperature. High diversity of two...... nonsynonymous mutations within the peptide-binding region of the major histocompatibility complex (MHC) class II (DAB) gene provided signatures of balancing selection. Weak signals for potential selection between sympatric resident and anadromous populations were revealed from genome scans and allele frequency...

  2. Left atrial volume and function in dogs with naturally occurring myxomatous mitral valve disease

    DEFF Research Database (Denmark)

    Höllmer, M.; Willesen, J. L.; Tolver, A.

    2017-01-01

    stroke volume increased, whereas LA reservoir and contractile function decreased with increasing disease severity. A maximal LA volume heart failure in dogs with chronic MMVD with a sensitivity of 96% and a specificity of 100......%. An active LA emptying fraction heart failure in dogs with chronic MMVD with a sensitivity of 77% and a specificity of 89% and a sensitivity of 82% and a specificity of 82%, respectively. CONCLUSION: Dogs with MMVD appear to have larger LA...... of cardiac compensation. Left atrial function in dogs with naturally occurring MMVD remains largely unexplored. The objective of this study was to evaluate LA volume and function in dogs with naturally occurring MMVD. ANIMALS: This prospective study included 205 client-owned dogs of different breeds, 114...

  3. Direct estimates of natural selection in Iberia indicate calcium absorption was not the only driver of lactase persistence in Europe.

    Science.gov (United States)

    Sverrisdóttir, Oddny Ósk; Timpson, Adrian; Toombs, Jamie; Lecoeur, Cecile; Froguel, Philippe; Carretero, Jose Miguel; Arsuaga Ferreras, Juan Luis; Götherström, Anders; Thomas, Mark G

    2014-04-01

    Lactase persistence (LP) is a genetically determined trait whereby the enzyme lactase is expressed throughout adult life. Lactase is necessary for the digestion of lactose--the main carbohydrate in milk--and its production is downregulated after the weaning period in most humans and all other mammals studied. Several sources of evidence indicate that LP has evolved independently, in different parts of the world over the last 10,000 years, and has been subject to strong natural selection in dairying populations. In Europeans, LP is strongly associated with, and probably caused by, a single C to T mutation 13,910 bp upstream of the lactase (LCT) gene (-13,910*T). Despite a considerable body of research, the reasons why LP should provide such a strong selective advantage remain poorly understood. In this study, we examine one of the most widely cited hypotheses for selection on LP--that fresh milk consumption supplemented the poor vitamin D and calcium status of northern Europe's early farmers (the calcium assimilation hypothesis). We do this by testing for natural selection on -13,910*T using ancient DNA data from the skeletal remains of eight late Neolithic Iberian individuals, whom we would not expect to have poor vitamin D and calcium status because of relatively high incident UVB light levels. None of the eight samples successfully typed in the study had the derived T-allele. In addition, we reanalyze published data from French Neolithic remains to both test for population continuity and further examine the evolution of LP in the region. Using simulations that accommodate genetic drift, natural selection, uncertainty in calibrated radiocarbon dates, and sampling error, we find that natural selection is still required to explain the observed increase in allele frequency. We conclude that the calcium assimilation hypothesis is insufficient to explain the spread of LP in Europe.

  4. Subtle but ubiquitous selection on body size in a natural population of collared flycatchers over 33 years.

    Science.gov (United States)

    Björklund, M; Gustafsson, L

    2017-07-01

    Understanding the magnitude and long-term patterns of selection in natural populations is of importance, for example, when analysing the evolutionary impact of climate change. We estimated univariate and multivariate directional, quadratic and correlational selection on four morphological traits (adult wing, tarsus and tail length, body mass) over a time period of 33 years (≈ 19 000 observations) in a nest-box breeding population of collared flycatchers (Ficedula albicollis). In general, selection was weak in both males and females over the years regardless of fitness measure (fledged young, recruits and survival) with only few cases with statistically significant selection. When data were analysed in a multivariate context and as time series, a number of patterns emerged; there was a consistent, but weak, selection for longer wings in both sexes, selection was stronger on females when the number of fledged young was used as a fitness measure, there were no indications of sexually antagonistic selection, and we found a negative correlation between selection on tarsus and wing length in both sexes but using different fitness measures. Uni- and multivariate selection gradients were correlated only for wing length and mass. Multivariate selection gradient vectors were longer than corresponding vector of univariate gradients and had more constrained direction. Correlational selection had little importance. Overall, the fitness surface was more or less flat with few cases of significant curvature, indicating that the adaptive peak with regard to body size in this species is broader than the phenotypic distribution, which has resulted in weak estimates of selection. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

  5. Selection of Objective Function For Imbalanced Classification: An Industrial Case Study

    DEFF Research Database (Denmark)

    Khan, Abdul Rauf; Schiøler, Henrik; Kulahci, Murat

    2017-01-01

    In this article we discuss the issue of selecting suitable objective function for Genetic Algorithm to solve an imbalanced classification problem. More precisely, first we discuss the need of specialized objective function to solve a real classification problem from our industrial partner and the...... and then we compare the results of our proposed objective function with commonly used candidates to serve this purpose. Our comparison is based on the analysis of real data collected during the quality control stages of the manufacturing process....

  6. Selective NOx Recirculation for Stationary Lean-Burn Natural Gas Engines

    Energy Technology Data Exchange (ETDEWEB)

    Nigel Clark; Gregory Thompson; Richard Atkinson; Richard Turton; Chamila Tissera; Emre Tatli; Andy Zimmerman

    2005-12-28

    Selective NOx Recirculation (SNR) involves cooling the engine exhaust gas and then adsorbing the oxides of nitrogen (NOx) from the exhaust stream, followed by the periodic desorption of NOx. By returning the desorbed, concentrated NOx into the engine intake and through the combustion chamber, a percentage of the NOx is decomposed during the combustion process. An initial study of NOx decomposition during lean-burn combustion was concluded in 2004 using a 1993 Cummins L10G 240hp natural gas engine. It was observed that the air/fuel ratio, injected NO (nitric oxide) quantity and engine operating points affected NOx decomposition rates of the engine. Chemical kinetic modeling results were also used to determine optimum NOx decomposition operating points and were published in the 2004 annual report. A NOx decomposition rate of 27% was measured from this engine under lean-burn conditions while the software model predicted between 35-42% NOx decomposition for similar conditions. A later technology 1998 Cummins L10G 280hp natural gas engine was procured with the assistance of Cummins Inc. to replace the previous engine used for 2005 experimental research. The new engine was equipped with an electronic fuel management system with closed-loop control that provided a more stable air/fuel ratio control and improved the repeatability of the tests. The engine was instrumented with an in-cylinder pressure measurement system and electronic controls, and was adapted to operate over a range of air/fuel ratios. The engine was connected to a newly commissioned 300hp alternating current (AC) motoring dynamometer. The second experimental campaign was performed to acquire both stoichiometric and slightly rich (0.97 lambda ratio) burn NOx decomposition rates. Effects of engine load and speed on decomposition were quantified, but Exhaust Gas Recirculation (EGR) was not varied independently. Decomposition rates of up to 92% were demonstrated. Following recommendations at the 2004 ARES peer

  7. A bayesian hierarchical model for classification with selection of functional predictors.

    Science.gov (United States)

    Zhu, Hongxiao; Vannucci, Marina; Cox, Dennis D

    2010-06-01

    In functional data classification, functional observations are often contaminated by various systematic effects, such as random batch effects caused by device artifacts, or fixed effects caused by sample-related factors. These effects may lead to classification bias and thus should not be neglected. Another issue of concern is the selection of functions when predictors consist of multiple functions, some of which may be redundant. The above issues arise in a real data application where we use fluorescence spectroscopy to detect cervical precancer. In this article, we propose a Bayesian hierarchical model that takes into account random batch effects and selects effective functions among multiple functional predictors. Fixed effects or predictors in nonfunctional form are also included in the model. The dimension of the functional data is reduced through orthonormal basis expansion or functional principal components. For posterior sampling, we use a hybrid Metropolis-Hastings/Gibbs sampler, which suffers slow mixing. An evolutionary Monte Carlo algorithm is applied to improve the mixing. Simulation and real data application show that the proposed model provides accurate selection of functional predictors as well as good classification.

  8. Directional Selection for Specific Sheep Cell Antibody Responses Affects Natural Rabbit Agglutinins of Chickens

    NARCIS (Netherlands)

    Cotter, P.F.; Ayoub, J.; Parmentier, H.K.

    2005-01-01

    Agglutination data from generations 8 through 19 indicate that bidirectional selection for specific SRBC antibody responses was successful in a line cross of ISA × Warren medium heavy layers. After 11 generations titers of the high SRBC selected line (H line) were nearly 1:32,000; those of the low

  9. Interspecific competition alters natural selection on shade avoidance phenotypes in Impatiens capensis.

    Science.gov (United States)

    McGoey, Brechann V; Stinchcombe, John R

    2009-08-01

    Shade avoidance syndrome is a known adaptive response for Impatiens capensis growing in dense intraspecific competition. However, I. capensis also grow with dominant interspecific competitors in marshes. Here, we compare the I. capensis shade-avoidance phenotypes produced in the absence and presence of heterospecific competitors, as well as selection on those traits. Two treatments were established in a marsh; in one treatment all heterospecifics were removed, while in the other, all competitors remained. We compared morphological traits, light parameters, seed output and, using phenotypic selection analysis, examined directional and nonlinear selection operating in the different competitive treatments. Average phenotypes, light parameters and seed production all varied depending on competitive treatment. Phenotypic selection analyses revealed different directional, disruptive, stabilizing and correlational selection. The disparities seen in both phenotypes and selection between the treatments related to the important differences in elongation timing depending on the presence of heterospecifics, although environmental covariances between traits and fitness could also contribute. Phenotypes produced by I. capensis depend on their competitive environment, and differing selection on shade-avoidance traits between competitive environments could indirectly select for increased plasticity given gene flow between populations in different competitive contexts.

  10. Uranium sorption to natural substrates-insights provided by isotope exchange, selective extraction and surface complexation modelling approaches

    International Nuclear Information System (INIS)

    Waite, T.D.; Payne T.E.; Davis, J.A.

    1993-01-01

    An extensive experimental program has been conducted over the last three years into the interaction of U(VI) with both single oxides and clays and complex natural substrates from the weathered zone in the vicinity of a uranium ore body in northern Australia. While iron oxides have frequently been considered to account for much of the uptake on such natural substrates, the results of laboratory open-quotes pH edgeclose quotes studies and of isotope exchange and selective extraction studies suggest that other phases must also play a significant role in controlling the partitioning of U(VI) between solid and solution phases. Supporting studies on kaolinite, the dominant clay in this system, provide insight into the most appropriate method of modelling the interaction of U(VI) with these natural substrates. The problems still remaining in adequately describing sorption of radionuclides and trace elements to complex natural substrates are discussed

  11. Naturally occurring circadian rhythm and sleep duration are related to executive functions in early adulthood.

    Science.gov (United States)

    Kuula, Liisa; Pesonen, Anu-Katriina; Heinonen, Kati; Kajantie, Eero; Eriksson, Johan Gunnar; Andersson, Sture; Lano, Aulikki; Lahti, Jari; Wolke, Dieter; Räikkönen, Katri

    2018-02-01

    Experimental sleep deprivation studies suggest that insufficient sleep and circadian misalignment associates with poorer executive function. It is not known whether this association translates to naturally occurring sleep patterns. A total of 512 of full-term-born members of the Arvo Ylppö Longitudinal Study [mean age = 25.3, standard deviation (SD) = 0.65] (44.3% men) wore actigraphs to define sleep duration, its irregularity and circadian rhythm (sleep mid-point) during a 1-week period (mean 6.9 nights, SD = 1.7). Performance-based executive function was assessed with the Trail-Making Test, Conners' Continuous Performance Test and Stroop. The self-rated adult version of Behavior Rating Inventory of Executive Function was used to assess trait-like executive function. We found that performance-based and self-reported trait-like executive function correlated only modestly (all correlations ≤0.17). Shorter sleep duration associated with more commission errors. Later circadian rhythm associated with poorer trait-like executive function, as indicated by the Brief Metacognitive Index and the Behavior Regulation Index. Those belonging to the group with the most irregular sleep duration performed slower than others in the Trail-Making Test Part A. All associations were adjusted for sex, age, socioeconomic status and body mass index. In conclusion, naturally occurring insufficient sleep and later circadian rhythm showed modest associations with poorer executive function. Shorter habitual sleep duration was associated with lower scores of performance-based tests of executive function, and later circadian rhythm was associated mainly with poorer trait-like executive function characteristics. Our findings suggest additionally that sleep duration and circadian rhythm associate with different domains of executive function, and there are no additive effects between the two. © 2017 European Sleep Research Society.

  12. Natural nano-structures on insects - possible functions of ordered arrays characterized by atomic force microscopy

    International Nuclear Information System (INIS)

    Watson, G.S.; Watson, J.A.

    2004-01-01

    Naturally occurring nano-structures is a much-neglected, but potentially rich, source of products that meet specifications imposed by natural selection. While the pharmaceutical industry has long recognized the value of natural compounds, the emerging industries based on nanotechnology have so far made little use of 'free' technology that has been 'invented' over evolutionary time-scales and driven by the imperatives of species survival. Ordered hexagonal packed array structures on cicada (e.g., Pflatoda claripennis) and termite (e.g., family Rhinotermitidae) wings have been investigated in this study. The spacings range from 200 to 1000 nm. The structures tend to have a rounded shape at the apex and protrude some 150-350 nm out from the surface plane. Wing structures with spacings at the lower end of the range are most likely optimized to serve as an anti-reflective coating (natural 'stealth technology') but may also act as a self-cleaning coating (the Lotus effect). Structures with spacings at the upper end of the range may provide mechanical strength to prevent load failure under flight and/or aid in the aerodynamic efficiency of the insect. This study demonstrates the multi-purpose design of natural structures

  13. Enhanced functional connectivity properties of human brains during in-situ nature experience

    Directory of Open Access Journals (Sweden)

    Zheng Chen

    2016-07-01

    Full Text Available In this study, we investigated the impacts of in-situ nature and urban exposure on human brain activities and their dynamics. We randomly assigned 32 healthy right-handed college students (mean age = 20.6 years, SD = 1.6; 16 males to a 20 min in-situ sitting exposure in either a nature (n = 16 or urban environment (n = 16 and measured their Electroencephalography (EEG signals. Analyses revealed that a brief in-situ restorative nature experience may induce more efficient and stronger brain connectivity with enhanced small-world properties compared with a stressful urban experience. The enhanced small-world properties were found to be correlated with “coherent” experience measured by Perceived Restorativeness Scale (PRS. Exposure to nature also induces stronger long-term correlated activity across different brain regions with a right lateralization. These findings may advance our understanding of the functional activities during in-situ environmental exposures and imply that a nature or nature-like environment may potentially benefit cognitive processes and mental well-being.

  14. Enhanced functional connectivity properties of human brains during in-situ nature experience.

    Science.gov (United States)

    Chen, Zheng; He, Yujia; Yu, Yuguo

    2016-01-01

    In this study, we investigated the impacts of in-situ nature and urban exposure on human brain activities and their dynamics. We randomly assigned 32 healthy right-handed college students (mean age = 20.6 years, SD = 1.6; 16 males) to a 20 min in-situ sitting exposure in either a nature (n = 16) or urban environment (n = 16) and measured their Electroencephalography (EEG) signals. Analyses revealed that a brief in-situ restorative nature experience may induce more efficient and stronger brain connectivity with enhanced small-world properties compared with a stressful urban experience. The enhanced small-world properties were found to be correlated with "coherent" experience measured by Perceived Restorativeness Scale (PRS). Exposure to nature also induces stronger long-term correlated activity across different brain regions with a right lateralization. These findings may advance our understanding of the functional activities during in-situ environmental exposures and imply that a nature or nature-like environment may potentially benefit cognitive processes and mental well-being.

  15. Evolution of natural agents: preservation, advance, and emergence of functional information.

    Science.gov (United States)

    Sharov, Alexei A

    2016-04-01

    Biological evolution is often viewed narrowly as a change of morphology or allele frequency in a sequence of generations. Here I pursue an alternative informational concept of evolution, as preservation, advance, and emergence of functional information in natural agents. Functional information is a network of signs (e.g., memory, transient messengers, and external signs) that are used by agents to preserve and regulate their functions. Functional information is preserved in evolution via complex interplay of copying and construction processes: the digital components are copied, whereas interpreting subagents together with scaffolds, tools, and resources, are constructed. Some of these processes are simple and invariant, whereas others are complex and contextual. Advance of functional information includes improvement and modification of already existing functions. Although the genome information may change passively and randomly, the interpretation is active and guided by the logic of agent behavior and embryonic development. Emergence of new functions is based on the reinterpretation of already existing information, when old tools, resources, and control algorithms are adopted for novel functions. Evolution of functional information progressed from protosemiosis, where signs correspond directly to actions, to eusemiosis, where agents associate signs with objects. Language is the most advanced form of eusemiosis, where the knowledge of objects and models is communicated between agents.

  16. Thermoelectric power plant selection using natural gas and sugar cane bagasse; Selecao de centrais termoeletricas utilizando gas natural e bagaco de cana

    Energy Technology Data Exchange (ETDEWEB)

    Leite, Caio de Paula [UNIFei - Faculdade de Engenharia Industrial, Sao Bernardo do Campo, SP (Brazil). Dept. de Engenharia Mecanica]. E-mail: cleite@edu.fei.br; Tribess, Arlindo [Sao Paulo Univ., SP (Brazil). Escola Politecnica. Dept. de Engenharia Mecanica]. E-mail: atribess@usp.br

    2003-07-01

    The electric power consumption in Brazil is growing about 4.2% a year, according to ELETROBRAS Decenal Plan in 1999. The capacity of installed electrical power is approximately 50000 MW, of the which 75% are in the Southern, South eastern and Middle western regions of the country. The growth rate indicates the need of an increase of the installed capacity of 2100 MW a year to avoid the risk of the lack of energy. On the other hand, the hydraulic potential sources of the region are practically exhausted and the government budget is low for this kind of investment. Therefore the solution would be the construction of new thermoelectric plants, with the possibility using natural gas and cane bagasse. The present work consists of the evaluation of the best option considering criterion of minimum cost for kWh of energy produced for the thermo electrical plants selection. Thermo economic analysis was made evaluating the production costs of steam and electricity in exergetic basis. The results show that the power cycles and cogeneration plants that use natural gas and cane bagasse are much more economical than the ones that just use natural gas, with 48% reduction of steam cost, 40% reduction of electricity cost generated b the steam turbine in the power cycle and 37% reduction of electricity cost generated by the steam turbine in the cogeneration plant, for cane bagasse price at 4 US$ /t and natural gas price at 140 US$/t. (author)

  17. Risk assessment of natural disasters in the course of selection of nuclear waste disposal

    International Nuclear Information System (INIS)

    Wu Weicheng; Ai Guigen

    1995-01-01

    Natural disasters are calamities which bring about enormous damage to human beings and their accommodations and equipment. Based on the research of disaster risk and example study of volcanism, we tried to carry out the risk assessment of natural disasters which potentially occur in the candidate area of nuclear waste disposal by three steps of analyses, defining the most frequent occurring area of disasters, determining the parameters of risk assessment and dividing the most dangerous site and risk grades

  18. Geomorphology and natural hazards of the selected glacial valleys, Cordillera Blanca, Peru

    Czech Academy of Sciences Publication Activity Database

    Klimeš, Jan

    2012-01-01

    Roč. 47, č. 2 (2012), s. 25-31 ISSN 0300-5402 R&D Projects: GA ČR(CZ) GAP209/11/1000 Institutional research plan: CEZ:AV0Z30460519 Keywords : geomorphologic map * natural hazards * glacial lakes Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://web.natur.cuni.cz/ksgrrsek/acta/2012/Geographica_2_2012_Klimes.pdf

  19. A simple and rapid method for calixarene-based selective extraction of bioactive molecules from natural products.

    Science.gov (United States)

    Segneanu, Adina-Elena; Damian, Daniel; Hulka, Iosif; Grozescu, Ioan; Salifoglou, Athanasios

    2016-03-01

    Natural products derived from medicinal plants have gained an important role in drug discovery due to their complex and abundant composition of secondary metabolites, with their structurally unique molecular components bearing a significant number of stereo-centers exhibiting high specificity linked to biological activity. Usually, the extraction process of natural products involves various techniques targeting separation of a specific class of compounds from a highly complex matrix. Aiding the process entails the use of well-defined and selective molecular extractants with distinctly configured structural attributes. Calixarenes conceivably belong to that class of molecules. They have been studied intensely over the years in an effort to develop new and highly selective receptors for biomolecules. These macrocycles, which display remarkable structural architectures and properties, could help usher a new approach in the efficient separation of specific classes of compounds from complex matrices in natural products. A simple and rapid such extraction method is presented herein, based on host-guest interaction(s) between a calixarene synthetic receptor, 4-tert-butyl-calix[6]arene, and natural biomolecular targets (amino acids and peptides) from Helleborus purpurascens and Viscum album. Advanced physicochemical methods (including GC-MS and chip-based nanoESI-MS analysis) suggest that the molecular structure and specifically the calixarene cavity size are closely linked to the nature of compounds separated. Incorporation of biomolecules and modification of the macrocyclic architecture during separation were probed and confirmed by scanning electronic microscopy and atomic force microscopy. The collective results project calixarene as a promising molecular extractant candidate, facilitating the selective separation of amino acids and peptides from natural products.

  20. Comparing the Selected Transfer Functions and Local Optimization Methods for Neural Network Flood Runoff Forecast

    Directory of Open Access Journals (Sweden)

    Petr Maca

    2014-01-01

    Full Text Available The presented paper aims to analyze the influence of the selection of transfer function and training algorithms on neural network flood runoff forecast. Nine of the most significant flood events, caused by the extreme rainfall, were selected from 10 years of measurement on small headwater catchment in the Czech Republic, and flood runoff forecast was investigated using the extensive set of multilayer perceptrons with one hidden layer of neurons. The analyzed artificial neural network models with 11 different activation functions in hidden layer were trained using 7 local optimization algorithms. The results show that the Levenberg-Marquardt algorithm was superior compared to the remaining tested local optimization methods. When comparing the 11 nonlinear transfer functions, used in hidden layer neurons, the RootSig function was superior compared to the rest of analyzed activation functions.

  1. Synthesis and Characterization of a Novel Microporous Dihydroxyl-Functionalized Triptycene-Diamine-Based Polyimide for Natural Gas Membrane Separation.

    Science.gov (United States)

    Alaslai, Nasser; Ma, Xiaohua; Ghanem, Bader; Wang, Yingge; Alghunaimi, Fahd; Pinnau, Ingo

    2017-09-01

    An intrinsically microporous polyimide is synthesized in m-cresol by a one-pot high-temperature condensation reaction of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and newly designed 2,6 (7)-dihydroxy-3,7(6)-diaminotriptycene (DAT1-OH). The 6FDA-DAT1-OH polyimide is thermally stable up to 440 °C, shows excellent solubility in polar solvents, and has moderately high Brunauer-Teller-Emmett (BET) surface area of 160 m 2 g -1 , as determined by nitrogen adsorption at -196 °C. Hydroxyl functionalization applied to the rigid 3D triptycene-based diamine building block results in a polyimide that exhibits moderate pure-gas CO 2 permeability of 70 Barrer combined with high CO 2 /CH 4 selectivity of 50. Mixed-gas permeation studies demonstrate excellent plasticization resistance of 6FDA-DAT1-OH with impressive performance as potential membrane material for natural gas sweetening with a CO 2 permeability of 50 Barrer and CO 2 /CH 4 selectivity of 40 at a typical natural gas well partial pressure of 10 atm. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Synthesis and Characterization of a Novel Microporous Dihydroxyl-Functionalized Triptycene-Diamine-Based Polyimide for Natural Gas Membrane Separation

    KAUST Repository

    Alaslai, Nasser Y.

    2017-07-10

    An intrinsically microporous polyimide is synthesized in m-cresol by a one-pot high-temperature condensation reaction of 4,4\\'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and newly designed 2,6 (7)-dihydroxy-3,7(6)-diaminotriptycene (DAT1-OH). The 6FDA-DAT1-OH polyimide is thermally stable up to 440 °C, shows excellent solubility in polar solvents, and has moderately high Brunauer-Teller-Emmett (BET) surface area of 160 m2 g-1 , as determined by nitrogen adsorption at -196 °C. Hydroxyl functionalization applied to the rigid 3D triptycene-based diamine building block results in a polyimide that exhibits moderate pure-gas CO2 permeability of 70 Barrer combined with high CO2 /CH4 selectivity of 50. Mixed-gas permeation studies demonstrate excellent plasticization resistance of 6FDA-DAT1-OH with impressive performance as potential membrane material for natural gas sweetening with a CO2 permeability of 50 Barrer and CO2 /CH4 selectivity of 40 at a typical natural gas well partial pressure of 10 atm.

  3. Selective Attention, Working Memory, and Executive Function as Potential Independent Sources of Cognitive Dysfunction in Schizophrenia.

    Science.gov (United States)

    Gold, James M; Robinson, Benjamin; Leonard, Carly J; Hahn, Britta; Chen, Shuo; McMahon, Robert P; Luck, Steven J

    2017-11-11

    People with schizophrenia demonstrate impairments in selective attention, working memory, and executive function. Given the overlap in these constructs, it is unclear if these represent distinct impairments or different manifestations of one higher-order impairment. To examine this question, we administered tasks from the basic cognitive neuroscience literature to measure visual selective attention, working memory capacity, and executive function in 126 people with schizophrenia and 122 healthy volunteers. Patients demonstrated deficits on all tasks with the exception of selective attention guided by strong bottom-up inputs. Although the measures of top-down control of selective attention, working memory, and executive function were all intercorrelated, several sources of evidence indicate that working memory and executive function are separate sources of variance. Specifically, both working memory and executive function independently contributed to the discrimination of group status and independently accounted for variance in overall general cognitive ability as assessed by the MATRICS battery. These two cognitive functions appear to be separable features of the cognitive impairments observed in schizophrenia. © The Author 2017. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  4. natural

    Directory of Open Access Journals (Sweden)

    Elías Gómez Macías

    2006-01-01

    Full Text Available Partiendo de óxido de magnesio comercial se preparó una suspensión acuosa, la cual se secó y calcinó para conferirle estabilidad térmica. El material, tanto fresco como usado, se caracterizó mediante DRX, área superficial BET y SEM-EPMA. El catalizador mostró una matriz de MgO tipo periclasa con CaO en la superficie. Las pruebas de actividad catalítica se efectuaron en lecho fijo empacado con partículas obtenidas mediante prensado, trituración y clasificación del material. El flujo de reactivos consistió en mezclas gas natural-aire por debajo del límite inferior de inflamabilidad. Para diferentes flujos y temperaturas de entrada de la mezcla reactiva, se midieron las concentraciones de CH4, CO2 y CO en los gases de combustión con un analizador de gases tipo infrarrojo no dispersivo (NDIR. Para alcanzar conversión total de metano se requirió aumentar la temperatura de entrada al lecho a medida que se incrementó el flujo de gases reaccionantes. Los resultados obtenidos permiten desarrollar un sistema de combustión catalítica de bajo costo con un material térmicamente estable, que promueva la alta eficiencia en la combustión de gas natural y elimine los problemas de estabilidad, seguridad y de impacto ambiental negativo inherentes a los procesos de combustión térmica convencional.

  5. Selection pressure transforms the nature of social dilemmas in adaptive networks

    Energy Technology Data Exchange (ETDEWEB)

    Van Segbroeck, Sven; Lenaerts, Tom [MLG, Universite Libre de Bruxelles, Boulevard du Triomphe-CP 212, 1050 Brussels (Belgium); Santos, Francisco C [CENTRIA, Departamento de Informatica, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Pacheco, Jorge M, E-mail: svsegbro@ulb.ac.be, E-mail: fcsantos@fct.unl.pt, E-mail: tlenaert@ulb.ac.be, E-mail: jmpacheco@math.uminho.pt [ATP-Group, CMAF, Complexo Interdisciplinar, P-1649-003 Lisboa Codex (Portugal)

    2011-01-15

    We have studied the evolution of cooperation in structured populations whose topology coevolves with the game strategies of the individuals. Strategy evolution proceeds according to an update rule with a free parameter, which measures the selection pressure. We explore how this parameter affects the interplay between network dynamics and strategy dynamics. A dynamical network topology can influence the strategy dynamics in two ways: (i) by modifying the expected payoff associated with each strategy and (ii) by reshaping the imitation network that underlies the evolutionary process. We show here that the selection pressure tunes the relative contribution of each of these two forces to the final outcome of strategy evolution. The dynamics of the imitation network plays only a minor role under strong selection, but becomes the dominant force under weak selection. We demonstrate how these findings constitute a mechanism supporting cooperative behavior.

  6. Selection pressure transforms the nature of social dilemmas in adaptive networks

    International Nuclear Information System (INIS)

    Van Segbroeck, Sven; Lenaerts, Tom; Santos, Francisco C; Pacheco, Jorge M

    2011-01-01

    We have studied the evolution of cooperation in structured populations whose topology coevolves with the game strategies of the individuals. Strategy evolution proceeds according to an update rule with a free parameter, which measures the selection pressure. We explore how this parameter affects the interplay between network dynamics and strategy dynamics. A dynamical network topology can influence the strategy dynamics in two ways: (i) by modifying the expected payoff associated with each strategy and (ii) by reshaping the imitation network that underlies the evolutionary process. We show here that the selection pressure tunes the relative contribution of each of these two forces to the final outcome of strategy evolution. The dynamics of the imitation network plays only a minor role under strong selection, but becomes the dominant force under weak selection. We demonstrate how these findings constitute a mechanism supporting cooperative behavior.

  7. Signatures of natural selection between life cycle stages separated by metamorphosis in European eel

    DEFF Research Database (Denmark)

    Pujolar, J.M.; Jacobsen, M.W.; Bekkevold, Dorte

    2015-01-01

    Species showing complex life cycles provide excellent opportunities to study the genetic associations between life cycle stages, as selective pressures may differ before and after metamorphosis. The European eel presents a complex life cycle with two metamorphoses, a first metamorphosis from larvae...... into glass eels (juvenile stage) and a second metamorphosis into silver eels (adult stage). We tested the hypothesis that different genes and gene pathways will be under selection at different life stages when comparing the genetic associations between glass eels and silver eels. Results: We used two sets...... of markers to test for selection: first, we genotyped individuals using a panel of 80 coding-gene single nucleotide polymorphisms (SNPs) developed in American eel; second, we investigated selection at the genome level using a total of 153,423 RAD-sequencing generated SNPs widely distributed across the genome...

  8. Estimation of demand function on natural gas and study of demand analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y.D. [Korea Energy Economics Institute, Euiwang (Korea, Republic of)

    1998-04-01

    Demand Function is estimated with several methods about the demand on natural gas, and analyzed per usage. Since the demand on natural gas, which has big share of heating use, has a close relationship with temperature, the inter-season trend of price and income elasticity is estimated considering temperature and economic formation. Per usage response of natural gas demand on the changes of price and income is also estimated. It was estimated that the response of gas demand on the changes of price and income occurs by the change of number of users in long term. In case of the response of unit consumption, only industrial use shows long-term response to price. Since gas price barely responds to the change of exchange rate, it seems to express the price-making mechanism that does not reflect timely the import condition such as exchange rate, etc. 16 refs., 12 figs., 13 tabs.

  9. Analysis and optimization with ecological objective function of irreversible single resonance energy selective electron heat engines

    International Nuclear Information System (INIS)

    Zhou, Junle; Chen, Lingen; Ding, Zemin; Sun, Fengrui

    2016-01-01

    Ecological performance of a single resonance ESE heat engine with heat leakage is conducted by applying finite time thermodynamics. By introducing Nielsen function and numerical calculations, expressions about power output, efficiency, entropy generation rate and ecological objective function are derived; relationships between ecological objective function and power output, between ecological objective function and efficiency as well as between power output and efficiency are demonstrated; influences of system parameters of heat leakage, boundary energy and resonance width on the optimal performances are investigated in detail; a specific range of boundary energy is given as a compromise to make ESE heat engine system work at optimal operation regions. Comparing performance characteristics with different optimization objective functions, the significance of selecting ecological objective function as the design objective is clarified specifically: when changing the design objective from maximum power output into maximum ecological objective function, the improvement of efficiency is 4.56%, while the power output drop is only 2.68%; when changing the design objective from maximum efficiency to maximum ecological objective function, the improvement of power output is 229.13%, and the efficiency drop is only 13.53%. - Highlights: • An irreversible single resonance energy selective electron heat engine is studied. • Heat leakage between two reservoirs is considered. • Power output, efficiency and ecological objective function are derived. • Optimal performance comparison for three objective functions is carried out.

  10. Genetic drift outweighs natural selection at toll-like receptor (TLR) immunity loci in a re-introduced population of a threatened species.

    Science.gov (United States)

    Grueber, Catherine E; Wallis, Graham P; Jamieson, Ian G

    2013-09-01

    During population establishment, genetic drift can be the key driver of changes in genetic diversity, particularly while the population is small. However, natural selection can also play a role in shaping diversity at functionally important loci. We used a well-studied, re-introduced population of the threatened Stewart Island robin (N = 722 pedigreed individuals) to determine whether selection shaped genetic diversity at innate immunity toll-like receptor (TLR) genes, over a 9-year period of population growth following establishment with 12 genetic founders. We found no evidence for selection operating with respect to TLR diversity on first-year overwinter survival for the majority of loci, genotypes and alleles studied. However, survival of individuals with TLR4BE genotype was significantly improved: these birds were less than half as likely to die prior to maturity compared with all other TLR4 genotypes. Furthermore, the population frequency of this genotype, at a two-fold excess over Hardy-Weinberg expectation, was increased by nonrandom mating. Near-complete sampling and full pedigree and reproductive data enabled us to eliminate other potential causes of these patterns including inbreeding, year effects, density dependence, selection on animals at earlier life history stages or genome-level association of the TLR4E allele with 'good genes'. However, comparison of observed levels of gene diversity to predictions under simulated genetic drift revealed results consistent with neutral expectations for all loci, including TLR4. Although selection favoured TLR4BE heterozygotes in this population, these effects were insufficient to outweigh genetic drift. This is the first empirical study to show that genetic drift can overwhelm natural selection in a wild population immediately following establishment. © 2013 John Wiley & Sons Ltd.

  11. Natural aminoacyl tRNA synthetase fragment enhances cardiac function after myocardial infarction.

    Directory of Open Access Journals (Sweden)

    Margaret E McCormick

    Full Text Available A naturally-occurring fragment of tyrosyl-tRNA synthetase (TyrRS has been shown in higher eukaryotes to 'moonlight' as a pro-angiogenic cytokine in addition to its primary role in protein translation. Pro-angiogenic cytokines have previously been proposed to be promising therapeutic mechanisms for the treatment of myocardial infarction. Here, we show that systemic delivery of the natural fragment of TyRS, mini-TyrRS, improves heart function in mice after myocardial infarction. This improvement is associated with reduced formation of scar tissue, increased angiogenesis of cardiac capillaries, recruitment of c-kitpos cells and proliferation of myocardial fibroblasts. This work demonstrates that mini-TyrRS has beneficial effects on cardiac repair and regeneration and offers support for the notion that elucidation of the ever expanding repertoire of noncanonical functions of aminoacyl tRNA synthetases offers unique opportunities for development of novel therapeutics.

  12. Chinese Function Manager of 2006 Partenariat Comments on the Selection Principle for Chinese Enterprises

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

      Fang Lei, EU-China Partenariat 2006Function Manager for Chinese Host Companies, worked together with Mr. Richard Morgan, EU Project Expert,Mr. Han Meiqing, Chinese Project Expert in the primary selection of Chinese enterprises.In reply to the strong request of the relevant governmental institutions, CCPIT and enterprises, he gave the following introductions about the details of selection.……

  13. Aesthetic Function Realized in the Selected Modern Chinese Essays by Zhang Peiji

    Institute of Scientific and Technical Information of China (English)

    罗丹

    2014-01-01

    The selected modern Chinese essays translated by Zhang Peiji is a masterpiece for Chinese scholars to do translation research. Prof. Zhang not only excels at translating the Chinese works accurately but also conveys the aesthetic value in the translated version. This paper wil analyse the aesthetic function used in Zhang Peiji’s selected modern Chinese essays from five aspects, music value, rhythm value, ful-grownness value, conciseness value and artistic conception value.

  14. First-generation Students’ Underperformance at University: The Impact of the Function of Selection

    Directory of Open Access Journals (Sweden)

    Mickaël eJury

    2015-05-01

    Full Text Available According to recent research, university not only has the role to educate and train students, it also has the role to select the best students. We argue that this function of selection disadvantages first-generation students, in comparison with continuing-generation students. Thus, the mere activation of the function of selection should be sufficient to produce achievement differences between first-generation and continuing-generation students in a novel academic task. Furthermore, we propose that when the function of selection is salient, first-generation students would be more vigilant to a cue that may confirm their inferiority, which should explain their underperformance. In the present experiment, participants were asked to complete an arithmetic modular task under two conditions, which either made the function of selection salient or reduced its importance. Participants’ vigilance to a threatening cue (i.e., their performance relative to others was measured through an eye-tracking technique. The results confirmed that first-generation students performed more poorly compared to continuing-generation students only when the function of selection was salient while no differences appeared in the no-selection condition. Regarding vigilance, the results did not confirm our hypothesis; thus, mediation path could not be tested. However, results indicated that at a high level of initial performance, first-generation students looked more often at the threatening cue. In others words, these students seemed more concerned about whether they were performing more poorly than others compared to their continuing-generation counterparts. Some methodological issues are discussed, notably regarding the measure of vigilance.

  15. Altering Height Data by Using Natural Logarithm as 3D Modelling Function for Reverse Engineering Application

    Science.gov (United States)

    Ilham Aminullah Abdulqawi, Nur; Salman Abu Mansor, Mohd

    2018-01-01

    The raw data extracted from reverse engineering based on vision mostly do not resemble the actual geometrical representation yet. Even though the higher object surface reflected the most visible light towards the camera and yield higher number of value based on Lambertian illumination model, this does not mean the curvature profile are always accurate. After all, there are many mathematical models to shape curvature profiles into the correct representation. However, one of the most appropriate models found is the natural logarithm function. The function itself has alteration properties towards the raw data generated from reverse engineering based on vision.

  16. Mental health, life functioning and risk factors among people exposed to frequent natural disasters and chronic poverty in Vietnam.

    Science.gov (United States)

    Pollack, Amie Alley; Weiss, Bahr; Trung, Lam Tu

    2016-06-01

    People living in low- and middle-income countries (LMIC) are at increased risk for exposure to major natural disasters, which places them at increased risk for mental health problems. Evidence is less clear, however, regarding the effects of less severe but more frequent natural disasters, which are likely to increase due to global climate change. To examine the mental health and life functioning, and their predictors, of people living in central coastal Vietnam, an area characterized by high risk for natural disasters and poverty. 1000 individuals were randomly selected from 5 provinces in central coastal Vietnam. Individuals were assessed cross-sectionally for exposure to major storms and other traumatic events (Post-traumatic Diagnostic Scale; PDS), financial stress (Chronic Financial Stress Scale), depression (PHQ-9), anxiety (GAD-7), PTSD (PDS), somatic syndrome (SCL-90-R), alcohol dependency (ICD-10), self-perceived general physical health (SF 36), and functional impairment (PDS life functioning section); caseness was determined using the various measures' algorithms. 22.7% percent of the sample ( n =227) met caseness criteria in one or more mental health domains, and 22.1% ( n =221) reported moderate to severe functional impairment. Lifetime exposure to typhoons and other major storms was 99% ( n =978), with 77% ( n =742) reporting traumatic major storm exposure. Moderate to high levels of financial stress were reported by 30% ( n =297). Frequency of exposure to major storms was not associated with increased risk for mental health problems but traumatic exposure to a major storm was. Overall, the strongest predictor of mental health problems was financial stress. Number of traumatic typhoons and other major storms in turn were significant predictors (r 2 = .03) of financial stress. The primary predictor of alcohol dependency was male gender, highlighting the importance of gender roles in development of alcohol abuse in countries like Vietnam. Individuals

  17. Electron-trapping probability in natural dosemeters as a function of irradiation temperature

    DEFF Research Database (Denmark)

    Wallinga, J.; Murray, A.S.; Wintle, A.G.

    2002-01-01

    The electron-trapping probability in OSL traps as a function of irradiation temperature is investigated for sedimentary quartz and feldspar. A dependency was found for both minerals; this phenomenon could give rise to errors in dose estimation when the irradiation temperature used in laboratory...... procedures is different from that in the natural environment. No evidence was found for the existence of shallow trap saturation effects that Could give rise to a dose-rate dependency of electron trapping....

  18. The selection function of the LAMOST Spectroscopic Survey of the Galactic Anti-centre

    Science.gov (United States)

    Chen, B.-Q.; Liu, X.-W.; Yuan, H.-B.; Xiang, M.-S.; Huang, Y.; Wang, C.; Zhang, H.-W.; Tian, Z.-J.

    2018-05-01

    We present a detailed analysis of the selection function of the LAMOST Spectroscopic Survey of the Galactic Anti-centre (LSS-GAC). LSS-GAC was designed to obtain low-resolution optical spectra for a sample of more than 3 million stars in the Galactic anti-centre. The second release of value-added catalogues of the LSS-GAC (LSS-GAC DR2) contains stellar parameters, including radial velocity, atmospheric parameters, elemental abundances, and absolute magnitudes deduced from 1.8 million spectra of 1.4 million unique stars targeted by the LSS-GAC between 2011 and 2014. For many studies using this data base, such as those investigating the chemodynamical structure of the Milky Way, a detailed understanding of the selection function of the survey is indispensable. In this paper, we describe how the selection function of the LSS-GAC can be evaluated to sufficient detail and provide selection function corrections for all spectroscopic measurements with reliable parameters released in LSS-GAC DR2. The results, to be released as new entries in the LSS-GAC value-added catalogues, can be used to correct the selection effects of the catalogue for scientific studies of various purposes.

  19. Functional analysis of AoAtg11 in selective autophagy in the filamentous fungus Aspergillus oryzae.

    Science.gov (United States)

    Tadokoro, Takayuki; Kikuma, Takashi; Kitamoto, Katsuhiko

    2015-07-01

    Autophagy is a highly conserved cellular degradation process in eukaryotes and consists of both non-selective and selective types. Selective autophagic processes include pexophagy, mitophagy, and the cytoplasm-to-vacuole targeting (Cvt) pathway of yeast, in which particular vacuolar proteins, such as aminopeptidase I (Ape1), are selectively transported to vacuoles. Although selective autophagy has been mainly studied in the yeasts Saccharomyces cerevisiae and Pichia pastoris, there is evidence for selective autophagy in filamentous fungi; however, the details are poorly understood. In S. cerevisiae, Atg11 is a selective autophagy-specific protein that recognizes and transports substrates to the pre-autophagosomal structure (PAS). Here, we first identified an ATG11 homologue in the filamentous fungus Aspergillus oryzae and analyzed the localization of the corresponding protein, designated AoAtg11, fused to enhanced green fluorescent protein (EGFP). Imaging analysis revealed that AoAtg11-EGFP was localized to PAS-like structures. We next constructed an Aoatg11 disruptant of A. oryzae and showed that AoAtg11 is involved in pexophagy and mitophagy. In addition, AoAtg11 was found to be dispensable for non-selective autophagy and for transporting AoApe1 to vacuoles. Taken together, these results suggest that AoAtg11 is a selective autophagy-specific protein in A. oryzae, and has distinct molecular functions from that of S. cerevisiae Atg11. Copyright © 2015 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  20. Synthesis selective transport properties of cleft-type ionophores having two convergent hydroxamic acid functions

    International Nuclear Information System (INIS)

    Kim, Duck Hee; Choi, Mi Jung; Chang, Suk Kyu

    2001-01-01

    A series of cleft-type ionophores having two convergent hydroxamic acid functions are prepared and their selective ionophoric properties toward heavy metal and transition metal ions have been investigated. Hydroxamic acids 3 exhibited a prominent selectivity toward heavy metal ions of Hg 2+ and Pb 2+ , and transition metal ions of Cu 2+ over other transition metal and alkaline earth metal ions from slightly acidic source phase (pH 6) to an acidic receiving phase (pH 1). Selective ionophoric properties toward Pb 2+ and Cu 2+ ions over other surveyed metal ions are also confirmed by the FAB-MS measurements