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Sample records for history dependent parrondo

  1. Parrondo Games with Spatial Dependence, III

    NASA Astrophysics Data System (ADS)

    Ethier, S. N.; Lee, Jiyeon

    2015-10-01

    We study Toral’s Parrondo games with N players and one-dimensional spatial dependence as modified by Xie et al. Specifically, we use computer graphics to sketch the Parrondo and anti-Parrondo regions for 3 ≤ N ≤ 9. Our work was motivated by a recent paper of Li et al., who applied a state space reduction method to this model, reducing the number of states from 2N to N + 1. We show that their reduced Markov chains are inconsistent with the model of Xie et al.

  2. Inefficiency of voting in Parrondo games

    NASA Astrophysics Data System (ADS)

    Dinís, Luis; Parrondo, Juan M. R.

    2004-11-01

    We study a modification of the so-called Parrondo's paradox where a large number of individuals choose the game they want to play by voting. We show that it can be better for the players to vote randomly than to vote according to their own benefit in one turn. The former yields a winning tendency while the latter results in steady losses. An explanation of this behaviour is given by noting that selfish voting prevents the switching between games that is essential for the total capital to grow. Results for both finite and infinite number of players are presented. It is shown that the extension of the model to the history-dependent Parrondo's paradox also displays the same effect.

  3. Brownian ratchets and Parrondo's games

    NASA Astrophysics Data System (ADS)

    Harmer, Gregory P.; Abbott, Derek; Taylor, Peter G.; Parrondo, Juan M. R.

    2001-09-01

    Parrondo's games present an apparently paradoxical situation where individually losing games can be combined to win. In this article we analyze the case of two coin tossing games. Game B is played with two biased coins and has state-dependent rules based on the player's current capital. Game B can exhibit detailed balance or even negative drift (i.e., loss), depending on the chosen parameters. Game A is played with a single biased coin that produces a loss or negative drift in capital. However, a winning expectation is achieved by randomly mixing A and B. One possible interpretation pictures game A as a source of "noise" that is rectified by game B to produce overall positive drift—as in a Brownian ratchet. Game B has a state-dependent rule that favors a losing coin, but when this state dependence is broken up by the noise introduced by game A, a winning coin is favored. In this article we find the parameter space in which the paradoxical effect occurs and carry out a winning rate analysis. The significance of Parrondo's games is that they are physically motivated and were originally derived by considering a Brownian ratchet—the combination of the games can be therefore considered as a discrete-time Brownian ratchet. We postulate the use of games of this type as a toy model for a number of physical and biological processes and raise a number of open questions for future research.

  4. Quantum models of Parrondo's games

    NASA Astrophysics Data System (ADS)

    Flitney, Adrian P.; Abbott, Derek

    2002-11-01

    It is possible to have two games that are losing when played in isolation but that, because of some form of feedback, produce a winning game when played alternately or even in a random mixture. This effect is known as Parrondo's paradox. Quantum mechanics provides novel methods of combining two games through interference and entanglement. Two models of quantum Parrondo's games have been published and these are reviewed here. We speculate on a model of a quantum Parrondo's game using entanglement. Such games could find a use in the development of algorithms for quantum computers.

  5. Mathematical background of Parrondo's paradox

    NASA Astrophysics Data System (ADS)

    Behrends, Ehrhard

    2004-05-01

    Parrondo's paradox states that there are losing gambling games which, when being combined stochastically or in a suitable deterministic way, give rise to winning games. Here we investigate the probabilistic background. We show how the properties of the equilibrium distributions of the Markov chains under consideration give rise to the paradoxical behavior, and we provide methods how to find the best a priori strategies.

  6. Parrondo's games and the zipping algorithm

    NASA Astrophysics Data System (ADS)

    Amengual, Pau; Toral, Raul

    2004-05-01

    We study the relation between the discrete-time version of the flashing ratchet known as Parrondo's games and a compression technique used very recently with thermal ratchets for evaluating the transfer of information -- negentropy -- between the Brownian particle and the source of fluctuations. We present some results concerning different versions of Parrondo's games showing, for each case, a good qualitative agreement between the gain and the inverse of the entropy.

  7. Extended Parrondo's game and Brownian ratchets: Strong and weak Parrondo effect

    NASA Astrophysics Data System (ADS)

    Wu, Degang; Szeto, Kwok Yip

    2014-02-01

    Inspired by the flashing ratchet, Parrondo's game presents an apparently paradoxical situation. Parrondo's game consists of two individual games, game A and game B. Game A is a slightly losing coin-tossing game. Game B has two coins, with an integer parameter M. If the current cumulative capital (in discrete unit) is a multiple of M, an unfavorable coin pb is used, otherwise a favorable pg coin is used. Paradoxically, a combination of game A and game B could lead to a winning game, which is the Parrondo effect. We extend the original Parrondo's game to include the possibility of M being either M1 or M2. Also, we distinguish between strong Parrondo effect, i.e., two losing games combine to form a winning game, and weak Parrondo effect, i.e., two games combine to form a better-performing game. We find that when M2 is not a multiple of M1, the combination of B (M1) and B (M2) has strong and weak Parrondo effect for some subsets in the parameter space (pb,pg), while there is neither strong nor weak effect when M2 is a multiple of M1. Furthermore, when M2 is not a multiple of M1, a stochastic mixture of game A may cancel the strong and weak Parrondo effect. Following a discretization scheme in the literature of Parrondo's game, we establish a link between our extended Parrondo's game with the analysis of discrete Brownian ratchet. We find a relation between the Parrondo effect of our extended model to the macroscopic bias in a discrete ratchet. The slope of a ratchet potential can be mapped to the fair game condition in the extended model, so that under some conditions, the macroscopic bias in a discrete ratchet can provide a good predictor for the game performance of the extended model. On the other hand, our extended model suggests a design of a ratchet in which the potential is a mixture of two periodic potentials.

  8. Simple games to illustrate Parrondo's paradox

    NASA Astrophysics Data System (ADS)

    Martin, Hal; von Baeyer, Hans Christian

    2004-05-01

    Parrondo's paradox is the proposition that two losing strategies can, by alternating randomly, produce a winner. R. D. Astumian has recently created a simple board game to illustrate this counterintuitive phenomenon. We prove that the inherent symmetry of Astumian's game prevents it from achieving its purpose, and suggest amended versions that do. We also display the additional paradoxical effect of two slow, losing games combining into a fast, winning one.

  9. Optimal strategies in collective Parrondo games

    NASA Astrophysics Data System (ADS)

    Dinis, L.; Parrondo, J. M. R.

    2003-08-01

    We present a modification of the so-called Parrondo's paradox where one is allowed to choose in each turn the game that a large number of individuals play. It turns out that, by choosing the game which gives the highest average earnings at each step, one ends up with systematic losses, whereas a periodic or random sequence of choices yields a steadily increase of the capital. An explanation of this behavior is given by noting that the short-range maximization of the returns is "killing the goose that laid the golden eggs". A continuous model displaying similar features is analyzed using dynamic programming techniques from control theory.

  10. An optical model for implementing Parrondo's game and designing stochastic game with long-term memory

    NASA Astrophysics Data System (ADS)

    Si, Tieyan

    2012-11-01

    An optical model of classical photons propagating through array of many beam splitters is developed to give a physical analogy of Parrondo's game and Parrondo-Harmer-Abbott game. We showed both the two games are reasonable game without so-called game paradox and they are essentially the same. We designed the games with long-term memory on loop lattice and history-entangled game. The strong correlation between nearest two rounds of game can make the combination of two losing game win, lose or oscillate between win and loss. The periodic potential in Brownian ratchet is analogous to a long chain of beam splitters. The coupling between two neighboring potential wells is equivalent to two coupled beam splitters. This correspondence may help us to understand the anomalous motion of exceptional Brownian particles moving in the opposite direction to the majority. We designed the capital wave for a game by introducing correlations into independent capitals instead of sub-games. Playing entangled quantum states in many coupled classical games obey the same rules for manipulating quantum states in many body physics.

  11. Lyapunov exponents, noise-induced synchronization, and Parrondo's paradox.

    PubMed

    Kocarev, Ljupco; Tasev, Zarko

    2002-04-01

    We show that Lyapunov exponents of a stochastic system, when computed for a specific realization of the noise process, are related to conditional Lyapunov exponents in deterministic systems. We propose to use the term stochastically induced regularity instead of noise-induced synchronization and explain the reason why. The nature of stochastically induced regularity is discussed: in some instances, it is a dynamical analog of Parrondo's paradox. PMID:12005984

  12. History-Dependent Random Discounting

    NASA Astrophysics Data System (ADS)

    Higashi, Youichiro; Hyogo, Kazuya; Takeoka, Norio

    2009-09-01

    In the literature of dynamic models under uncertainty, it is commonly assumed that uncertainty is resolved gradually over time and its resolution is independent of the actions taken by a decision maker up to that time period. However, contingencies in the decision maker's mind may change and even increase over time according to habits that have evolved by experiences, actions, or consumptions in the past. We provide an axiomatic model where the decision maker faces uncertainty about her own time preference or discount factors in future and these uncertainty may evolve according to histories or habits from the past consumption.

  13. Maximal Parrondo's Paradox for Classical and Quantum Markov Chains

    NASA Astrophysics Data System (ADS)

    Grünbaum, F. Alberto; Pejic, Michael

    2016-02-01

    Parrondo's paradox refers to the situation where two, multi-round games with a fixed winning criteria, both with probability greater than one-half for one player to win, are combined. Using a possibly biased coin to determine the rule to employ for each round, paradoxically, the previously losing player now wins the combined game with probability greater than one-half. In this paper, we will analyze classical observed, classical hidden, and quantum versions of a game that displays this paradox. The game we have utilized is simpler than games for which this behavior has been previously noted in the classical and quantum cases. We will show that in certain situations the paradox can occur to a greater degree in the quantum version than is possible in the classical versions.

  14. Quantum Bayesian networks with application to games displaying Parrondo's paradox

    NASA Astrophysics Data System (ADS)

    Pejic, Michael

    Bayesian networks and their accompanying graphical models are widely used for prediction and analysis across many disciplines. We will reformulate these in terms of linear maps. This reformulation will suggest a natural extension, which we will show is equivalent to standard textbook quantum mechanics. Therefore, this extension will be termed quantum. However, the term quantum should not be taken to imply this extension is necessarily only of utility in situations traditionally thought of as in the domain of quantum mechanics. In principle, it may be employed in any modelling situation, say forecasting the weather or the stock market---it is up to experiment to determine if this extension is useful in practice. Even restricting to the domain of quantum mechanics, with this new formulation the advantages of Bayesian networks can be maintained for models incorporating quantum and mixed classical-quantum behavior. The use of these will be illustrated by various basic examples. Parrondo's paradox refers to the situation where two, multi-round games with a fixed winning criteria, both with probability greater than one-half for one player to win, are combined. Using a possibly biased coin to determine the rule to employ for each round, paradoxically, the previously losing player now wins the combined game with probabilitygreater than one-half. Using the extended Bayesian networks, we will formulate and analyze classical observed, classical hidden, and quantum versions of a game that displays this paradox, finding bounds for the discrepancy from naive expectations for the occurrence of the paradox. A quantum paradox inspired by Parrondo's paradox will also be analyzed. We will prove a bound for the discrepancy from naive expectations for this paradox as well. Games involving quantum walks that achieve this bound will be presented.

  15. Winning in sequential Parrondo games by players with short-term memory

    NASA Astrophysics Data System (ADS)

    Cheung, K. W.; Ma, H. F.; Wu, D.; Lui, G. C.; Szeto, K. Y.

    2016-05-01

    The original Parrondo game, denoted as AB3, contains two independent games: A and B. The winning or losing of games A and B is defined by the change of one unit of capital. Game A is a losing game if played continuously, with winning probability p=0.5-ε , where ε =0.003 . Game B is also losing and has two coins: a good coin with winning probability {{p}\\text{g}}=0.75-ε is used if the player’s capital is not divisible by 3, otherwise a bad coin with winning probability {{p}\\text{b}}=0.1-ε is used. The Parrondo paradox refers to the situation where the mixture of games A and B in a sequence leads to winning in the long run. The paradox can be resolved using Markov chain analysis. We extend this setting of the Parrondo game to involve players with one-step memory. The player can win by switching his choice of A or B game in a Parrondo game sequence. If the player knows the identity of the game he plays and the state of his capital, then the player can win maximally. On the other hand, if the player does not know the nature of the game, then he is playing a (C, D) game, where either (C  =  A, D  =  B), or (C  =  B, D  =  A). For a player with one-step memory playing the AB3 game, he can achieve the highest expected gain with switching probability equal to 3/4 in the (C, D) game sequence. This result has been found first numerically and then proven analytically. Generalization to an AB mod(M) Parrondo game for other integers M has been made for the general domain of parameters {{p}\\text{b}}\\text{A}}<{{p}\\text{g}} . We find that for odd M the Parrondo effect does exist. However, for even M, there is no Parrondo effect for two cases: the initial game is A and the initial capital is even, or the initial game is B and the initial capital is odd. There is still a possibility of the Parrondo effect for the other two cases when M is even: the initial game is A and the initial capital is odd, or the initial game is B and the initial

  16. ''Illusion of control'' in Time-Horizon Minority and Parrondo Games

    NASA Astrophysics Data System (ADS)

    Satinover, J. B.; Sornette, D.

    2007-12-01

    Human beings like to believe they are in control of their destiny. This ubiquitous trait seems to increase motivation and persistence, and is probably evolutionarily adaptive [J.D. Taylor, S.E. Brown, Psych. Bull. 103, 193 (1988); A. Bandura, Self-efficacy: the exercise of control (WH Freeman, New York, 1997)]. But how good really is our ability to control? How successful is our track record in these areas? There is little understanding of when and under what circumstances we may over-estimate [E. Langer, J. Pers. Soc. Psych. 7, 185 (1975)] or even lose our ability to control and optimize outcomes, especially when they are the result of aggregations of individual optimization processes. Here, we demonstrate analytically using the theory of Markov Chains and by numerical simulations in two classes of games, the Time-Horizon Minority Game [M.L. Hart, P. Jefferies, N.F. Johnson, Phys. A 311, 275 (2002)] and the Parrondo Game [J.M.R. Parrondo, G.P. Harmer, D. Abbott, Phys. Rev. Lett. 85, 5226 (2000); J.M.R. Parrondo, How to cheat a bad mathematician (ISI, Italy, 1996)], that agents who optimize their strategy based on past information may actually perform worse than non-optimizing agents. In other words, low-entropy (more informative) strategies under-perform high-entropy (or random) strategies. This provides a precise definition of the “illusion of control” in certain set-ups a priori defined to emphasize the importance of optimization.

  17. Viscoplastic constitutive relationships with dependence on thermomechanical history

    NASA Technical Reports Server (NTRS)

    Robinson, D. N.; Bartolotta, P. A.

    1985-01-01

    Experimental evidence of thermomechanical history dependence in the cyclic hardening behavior of some common high-temperature structural alloys is presented with special emphasis on dynamic metallurgical changes. The inadequacy of formulating nonisothermal constitutive equations solely on the basis of isothermal testing is discussed. A representation of thermoviscoplasticity is proposed that qualitatively accounts for the observed hereditary behavior. This is achieved by formulating the scalar evolutionary equation in an established viscoplasticity theory to reflect thermomechanical path dependence. To assess the importance of accounting for thermomechanical history dependence in practical structural analyses, two qualitative models are specified: (1) formulated as if based entirely on isothermal information; (2) to reflect thermomechanical path dependence using the proposed thermoviscoplastic representation. Predictions of the two models are compared and the impact the calculated differences in deformation behavior may have on subsequent lifetime predictions is discussed.

  18. History dependent quantum random walks as quantum lattice gas automata

    NASA Astrophysics Data System (ADS)

    Shakeel, Asif; Meyer, David A.; Love, Peter J.

    2014-12-01

    Quantum Random Walks (QRW) were first defined as one-particle sectors of Quantum Lattice Gas Automata (QLGA). Recently, they have been generalized to include history dependence, either on previous coin (internal, i.e., spin or velocity) states or on previous position states. These models have the goal of studying the transition to classicality, or more generally, changes in the performance of quantum walks in algorithmic applications. We show that several history dependent QRW can be identified as one-particle sectors of QLGA. This provides a unifying conceptual framework for these models in which the extra degrees of freedom required to store the history information arise naturally as geometrical degrees of freedom on the lattice.

  19. History dependent quantum random walks as quantum lattice gas automata

    SciTech Connect

    Shakeel, Asif E-mail: dmeyer@math.ucsd.edu Love, Peter J. E-mail: dmeyer@math.ucsd.edu; Meyer, David A. E-mail: dmeyer@math.ucsd.edu

    2014-12-15

    Quantum Random Walks (QRW) were first defined as one-particle sectors of Quantum Lattice Gas Automata (QLGA). Recently, they have been generalized to include history dependence, either on previous coin (internal, i.e., spin or velocity) states or on previous position states. These models have the goal of studying the transition to classicality, or more generally, changes in the performance of quantum walks in algorithmic applications. We show that several history dependent QRW can be identified as one-particle sectors of QLGA. This provides a unifying conceptual framework for these models in which the extra degrees of freedom required to store the history information arise naturally as geometrical degrees of freedom on the lattice.

  20. Dependence of CdTe response of bias history

    SciTech Connect

    Sites, J.R.; Sasala, R.A.; Eisgruber, I.L.

    1995-11-01

    Several time-dependent effect have been observed in CdTe cells and modules in recent years. Some appear to be related to degradation at the back contact, some to changes in temperature at the thin-film junction, and some to the bias history of the cell or module. Back-contact difficulties only occur in some cases, and the other two effects are reversible. Nevertheless, confusion in data interpretation can arise when these effects are not characterized. This confusion can be particularly acute when more than one time-dependent effect occurs during the same measurement cycle. The purpose of this presentation is to help categorize time-dependent effects in CdTe and other thin-film cells to elucidate those related to bias history, and to note differences between cell and module analysis.

  1. History-dependent dissipative vortex dynamics in superconducting arrays

    NASA Astrophysics Data System (ADS)

    Durkin, Malcolm; Mondragon-Shem, Ian; Eley, Serena; Hughes, Taylor L.; Mason, Nadya

    2016-07-01

    We perform current (I )-voltage (V ) measurements on low resistance superconductor-normal-superconductor arrays in finite magnetic fields, focusing on the dilute vortex population regime. We observe significant deviations from predicted behavior, notably the absence of a differential resistance peak near the vortex depinning current, and a broad linear I -V region with an extrapolated I intercept equal to the depinning current. Comparing these results to an overdamped molecular vortex model, we find that this behavior can be explained by the presence of a history-dependent dissipative force. This approach has not been considered previously, to our knowledge, yet it is crucial for obtaining a correct description of the vortex dynamics in superconducting arrays.

  2. A History of Spike-Timing-Dependent Plasticity

    PubMed Central

    Markram, Henry; Gerstner, Wulfram; Sjöström, Per Jesper

    2011-01-01

    How learning and memory is achieved in the brain is a central question in neuroscience. Key to today’s research into information storage in the brain is the concept of synaptic plasticity, a notion that has been heavily influenced by Hebb's (1949) postulate. Hebb conjectured that repeatedly and persistently co-active cells should increase connective strength among populations of interconnected neurons as a means of storing a memory trace, also known as an engram. Hebb certainly was not the first to make such a conjecture, as we show in this history. Nevertheless, literally thousands of studies into the classical frequency-dependent paradigm of cellular learning rules were directly inspired by the Hebbian postulate. But in more recent years, a novel concept in cellular learning has emerged, where temporal order instead of frequency is emphasized. This new learning paradigm – known as spike-timing-dependent plasticity (STDP) – has rapidly gained tremendous interest, perhaps because of its combination of elegant simplicity, biological plausibility, and computational power. But what are the roots of today’s STDP concept? Here, we discuss several centuries of diverse thinking, beginning with philosophers such as Aristotle, Locke, and Ribot, traversing, e.g., Lugaro’s plasticità and Rosenblatt’s perceptron, and culminating with the discovery of STDP. We highlight interactions between theoretical and experimental fields, showing how discoveries sometimes occurred in parallel, seemingly without much knowledge of the other field, and sometimes via concrete back-and-forth communication. We point out where the future directions may lie, which includes interneuron STDP, the functional impact of STDP, its mechanisms and its neuromodulatory regulation, and the linking of STDP to the developmental formation and continuous plasticity of neuronal networks. PMID:22007168

  3. Dynamics of history-dependent epidemics in temporal networks

    NASA Astrophysics Data System (ADS)

    Sunny, Albert; Kotnis, Bhushan; Kuri, Joy

    2015-08-01

    The structural properties of temporal networks often influence the dynamical processes that occur on these networks, e.g., bursty interaction patterns have been shown to slow down epidemics. In this paper, we investigate the effect of link lifetimes on the spread of history-dependent epidemics. We formulate an analytically tractable activity-driven temporal network model that explicitly incorporates link lifetimes. For Markovian link lifetimes, we use mean-field analysis for computing the epidemic threshold, while the effect of non-Markovian link lifetimes is studied using simulations. Furthermore, we also study the effect of negative correlation between the number of links spawned by an individual and the lifetimes of those links. Such negative correlations may arise due to the finite cognitive capacity of the individuals. Our investigations reveal that heavy-tailed link lifetimes slow down the epidemic, while negative correlations can reduce epidemic prevalence. We believe that our results help shed light on the role of link lifetimes in modulating diffusion processes on temporal networks.

  4. Size-dependent mortality induces life-history changes mediated through population dynamical feedbacks.

    PubMed

    van Kooten, Tobias; Persson, Lennart; de Roos, André M

    2007-08-01

    The majority of taxa grow significantly during life history, which often leads to individuals of the same species having different ecological roles, depending on their size or life stage. One aspect of life history that changes during ontogeny is mortality. When individual growth and development are resource dependent, changes in mortality can affect the outcome of size-dependent intraspecific resource competition, in turn affecting both life history and population dynamics. We study the outcome of varying size-dependent mortality on two life-history types, one that feeds on the same resource throughout life history and another that can alternatively cannibalize smaller conspecifics. Compensatory responses in the life history dampen the effect of certain types of size-dependent mortality, while other types of mortality lead to dramatic changes in life history and population dynamics, including population (de-)stabilization, and the growth of cannibalistic giants. These responses differ strongly among the two life-history types. Our analysis provides a mechanistic understanding of the population-level effects that come about through the interaction between individual growth and size-dependent mortality, mediated by resource dependence in individual vital rates. PMID:17874376

  5. History of sexual abuse and suicide attempts in alcohol-dependent patients.

    PubMed

    Jakubczyk, A; Klimkiewicz, A; Krasowska, A; Kopera, M; Sławińska-Ceran, A; Brower, K J; Wojnar, M

    2014-09-01

    History of child abuse is considered one of the important risk factors of suicide attempt in general population. At the same time it has been shown that suicide attempts appear significantly more frequently in alcoholics than in healthy individuals. The objective of this study was to investigate associations between history of childhood sexual abuse and suicide attempts in a sample of Polish alcohol dependent patients. A sample of 364 alcohol-dependent subjects was recruited in alcohol treatment centers in Warsaw, Poland. Information was obtained about demographics, family history of psychiatric problems, history of suicide attempts, sexual and physical abuse during childhood and adulthood and severity of alcohol problems. When analyzed by gender, 7.4% of male and 39.2% of female patients had a lifetime history of sexual abuse; 31.9% of the study group reported at least one suicide attempt during their lifetime. Patients who reported suicide attempts were significantly younger (p=0.0008), had greater severity of alcohol dependence (p=0.0002), lower social support (p=0.003), and worse economic status (p=0.002). Moreover, there was a significant association between history of suicide attempts and family history of psychiatric problems (p=0.00025), suicide attempts in the family (p=0.0073), childhood history of sexual abuse (p=0.009) as well as childhood history of physical abuse (p=0.002). When entered into linear regression analysis with other dependent variables history of childhood sexual abuse remained a significant predictor of suicide attempt (OR=2.52; p=0.035). Lifetime experience of sexual abuse is a significant and independent risk factor of suicide attempts in alcohol-dependent individuals. PMID:24997776

  6. Evolutionary history and distance dependence control survival of dipterocarp seedlings.

    PubMed

    Bagchi, Robert; Press, Malcolm C; Scholes, Julie D

    2010-01-01

    One important hypothesis to explain tree-species coexistence in tropical forests suggests that increased attack by natural enemies near conspecific trees gives locally rare species a competitive advantage. Host ranges of natural enemies generally encompass several closely related plant taxa suggesting that seedlings should also do poorly around adults of closely related species. We investigated the effects of adult Parashorea malaanonan on seedling survival in a Bornean rain forest. Survival of P. malaanonan seedlings was highest at intermediate distances from parent trees while heterospecific seedlings were unaffected by distance. Leaf herbivores did not drive this relationship. Survival of seedlings was lowest for P. malaanonan, and increased with phylogenetic dissimilarity from this species, suggesting that survival of close relatives of common species is reduced. This study suggests that distance dependence contributes to species coexistence and highlights the need for further investigation into the role of shared plant enemies in community dynamics. PMID:19849708

  7. Life history dependent morphometric variation in stream-dwelling Atlantic salmon

    USGS Publications Warehouse

    Letcher, B.H.

    2003-01-01

    The time course of morphometric variation among life histories for stream-dwelling Atlantic salmon (Salmo salar L.) parr (age-0+ to age-2+) was analyzed. Possible life histories were combinations of parr maturity status in the autumn (mature or immature) and age at outmigration (smolt at age-2+ or later age). Actual life histories expressed with enough fish for analysis in the 1997 cohort were immature/age-2+ smolt, mature/age-2 +smolt, and mature/age-2+ non-smolt. Tagged fish were assigned to one of the three life histories and digital pictures from the field were analyzed using landmark-based geometric morphometrics. Results indicated that successful grouping of fish according to life history varied with fish age, but that fish could be grouped before the actual expression of the life histories. By March (age-1+), fish were successfully grouped using a descriptive discriminant function and successful assignment ranged from 84 to 97% for the remainder of stream residence. A jackknife of the discriminant function revealed an average life history prediction success of 67% from age-1+ summer to smolting. Low sample numbers for one of the life histories may have limited prediction success. A MANOVA on the shape descriptors (relative warps) also indicated significant differences in shape among life histories from age-1+ summer through to smolting. Across all samples, shape varied significantly with size. Within samples, shape did not vary significantly with size for samples from December (age-0+) to May (age-1+). During the age-1+ summer however, shape varied significantly with size, but the relationship between shape and size was not different among life histories. In the autumn (age-1+) and winter (age-2+), life history differences explained a significant portion of the change in shape with size. Life history dependent morphometric variation may be useful to indicate the timing of early expressions of life history variation and as a tool to explore temporal and

  8. Thermomagnetic history dependence of magnetocaloric effect in Ni50Mn34In16

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, M. K.; Sharma, V. K.; Roy, S. B.

    2008-01-01

    A large inverse magnetocaloric effect has been reported to be associated with the austenite to martensite phase transition in Ni50Mn34In16. It is shown here that the magnitude of the observed magnetocaloric effect as well as effective refrigerant capacity depend significantly on the thermo-magnetic history of the sample.

  9. Frequency and Density-Dependent Selection on Life-History Strategies – A Field Experiment

    PubMed Central

    Mappes, Tapio; Koivula, Minna; Koskela, Esa; Oksanen, Tuula A.; Savolainen, Tiina; Sinervo, Barry

    2008-01-01

    Negative frequency-dependence, which favors rare genotypes, promotes the maintenance of genetic variability and is of interest as a potential explanation for genetic differentiation. Density-dependent selection may also promote cyclic changes in frequencies of genotypes. Here we show evidence for both density-dependent and negative frequency-dependent selection on opposite life-history tactics (low or high reproductive effort, RE) in the bank vole (Myodes glareolus). Density-dependent selection was evident among the females with low RE, which were especially favored in low densities. Instead, both negative frequency-dependent and density-dependent selection were shown in females with high RE, which were most successful when they were rare in high densities. Furthermore, selection at the individual level affected the frequencies of tactics at the population level, so that the frequency of the rare high RE tactic increased significantly at high densities. We hypothesize that these two selection mechanisms (density- and negative frequency-dependent selection) may promote genetic variability in cyclic mammal populations. Nevertheless, it remains to be determined whether the origin of genetic variance in life-history traits is causally related to density variation (e.g. population cycles). PMID:18301764

  10. History-dependent friction and slow slip from time-dependent microscopic junction laws studied in a statistical framework.

    PubMed

    Thøgersen, Kjetil; Trømborg, Jørgen Kjoshagen; Sveinsson, Henrik Andersen; Malthe-Sørenssen, Anders; Scheibert, Julien

    2014-05-01

    To study how macroscopic friction phenomena originate from microscopic junction laws, we introduce a general statistical framework describing the collective behavior of a large number of individual microjunctions forming a macroscopic frictional interface. Each microjunction can switch in time between two states: a pinned state characterized by a displacement-dependent force and a slipping state characterized by a time-dependent force. Instead of tracking each microjunction individually, the state of the interface is described by two coupled distributions for (i) the stretching of pinned junctions and (ii) the time spent in the slipping state. This framework allows for a whole family of microjunction behavior laws, and we show how it represents an overarching structure for many existing models found in the friction literature. We then use this framework to pinpoint the effects of the time scale that controls the duration of the slipping state. First, we show that the model reproduces a series of friction phenomena already observed experimentally. The macroscopic steady-state friction force is velocity dependent, either monotonic (strengthening or weakening) or nonmonotonic (weakening-strengthening), depending on the microscopic behavior of individual junctions. In addition, slow slip, which has been reported in a wide variety of systems, spontaneously occurs in the model if the friction contribution from junctions in the slipping state is time weakening. Next, we show that the model predicts a nontrivial history dependence of the macroscopic static friction force. In particular, the static friction coefficient at the onset of sliding is shown to increase with increasing deceleration during the final phases of the preceding sliding event. We suggest that this form of history dependence of static friction should be investigated in experiments, and we provide the acceleration range in which this effect is expected to be experimentally observable. PMID:25353806

  11. Past present: Relationship dynamics may differ among discordant gay male couples depending on HIV infection history

    PubMed Central

    Beougher, Sean C.; Mandic, Carmen Gómez; Darbes, Lynae A.; Chakravarty, Deepalika; Neilands, Torsten B.; Garcia, Carla C.; Hoff, Colleen C.

    2013-01-01

    Discordant couples are unique because neither partner shares the same serostatus. Yet research overlooks how they became discordant, mistakenly assuming that they have always been that way and, by extension, that being discordant impacts the relationship in a similar manner. This study examines HIV infection history and its impact on relationship dynamics using qualitative data from 35 discordant gay male couples. Most couples met discordant (69%); however, many did not (31%). Those couples that met discordant felt being discordant had a lesser impact on their sexual and relational satisfaction, while those that did not meet discordant felt it had a greater impact, reporting sexual frustration and anxiety over seroconverting. This suggests that relationship dynamics may differ for discordant couples depending on HIV infection history. HIV prevention and counseling services for discordant couples can be better tailored and more effective when differences in HIV infection history are recognized. PMID:24244082

  12. Past present: Relationship dynamics may differ among discordant gay male couples depending on HIV infection history.

    PubMed

    Beougher, Sean C; Mandic, Carmen Gómez; Darbes, Lynae A; Chakravarty, Deepalika; Neilands, Torsten B; Garcia, Carla C; Hoff, Colleen C

    2013-10-01

    Discordant couples are unique because neither partner shares the same serostatus. Yet research overlooks how they became discordant, mistakenly assuming that they have always been that way and, by extension, that being discordant impacts the relationship in a similar manner. This study examines HIV infection history and its impact on relationship dynamics using qualitative data from 35 discordant gay male couples. Most couples met discordant (69%); however, many did not (31%). Those couples that met discordant felt being discordant had a lesser impact on their sexual and relational satisfaction, while those that did not meet discordant felt it had a greater impact, reporting sexual frustration and anxiety over seroconverting. This suggests that relationship dynamics may differ for discordant couples depending on HIV infection history. HIV prevention and counseling services for discordant couples can be better tailored and more effective when differences in HIV infection history are recognized. PMID:24244082

  13. Correcting the initialization of models with fractional derivatives via history-dependent conditions

    NASA Astrophysics Data System (ADS)

    Du, Maolin; Wang, Zaihua

    2016-04-01

    Fractional differential equations are more and more used in modeling memory (history-dependent, non-local, or hereditary) phenomena. Conventional initial values of fractional differential equations are defined at a point, while recent works define initial conditions over histories. We prove that the conventional initialization of fractional differential equations with a Riemann-Liouville derivative is wrong with a simple counter-example. The initial values were assumed to be arbitrarily given for a typical fractional differential equation, but we find one of these values can only be zero. We show that fractional differential equations are of infinite dimensions, and the initial conditions, initial histories, are defined as functions over intervals. We obtain the equivalent integral equation for Caputo case. With a simple fractional model of materials, we illustrate that the recovery behavior is correct with the initial creep history, but is wrong with initial values at the starting point of the recovery. We demonstrate the application of initial history by solving a forced fractional Lorenz system numerically.

  14. Correcting the initialization of models with fractional derivatives via history-dependent conditions

    NASA Astrophysics Data System (ADS)

    Du, Maolin; Wang, Zaihua

    2015-08-01

    Fractional differential equations are more and more used in modeling memory (history-dependent, non-local, or hereditary) phenomena. Conventional initial values of fractional differential equations are defined at a point, while recent works define initial conditions over histories. We prove that the conventional initialization of fractional differential equations with a Riemann-Liouville derivative is wrong with a simple counter-example. The initial values were assumed to be arbitrarily given for a typical fractional differential equation, but we find one of these values can only be zero. We show that fractional differential equations are of infinite dimensions, and the initial conditions, initial histories, are defined as functions over intervals. We obtain the equivalent integral equation for Caputo case. With a simple fractional model of materials, we illustrate that the recovery behavior is correct with the initial creep history, but is wrong with initial values at the starting point of the recovery. We demonstrate the application of initial history by solving a forced fractional Lorenz system numerically.

  15. Density-dependent life-history compensation of an iteroparous salmonid.

    PubMed

    Johnston, Fiona D; Post, John R

    2009-03-01

    Over the course of a decade, the bull trout (Salvelinus confluentus) population in Lower Kananaskis Lake, Alberta, Canada, recovered from a heavily overexploited state, experiencing a 28-fold increase in adult abundance after the implementation of zero-harvest regulations. This system provided a unique opportunity to monitor the changes in life-history characteristics in a natural population throughout the recovery process. The purpose of this study was to examine the degree to which life-history traits were able to compensate for harvest-induced changes and the implications of this for management. Density-dependent changes in growth, survival, and reproductive life-history characteristics were observed. As density increased, maturation was delayed, and the frequency of skipped reproductive events, primarily by individuals of poor condition, increased. However, size at maturation and the proportion of fish skipping reproduction differed between the sexes, suggesting that life-history trade-offs differ between the sexes. The rapid response of these life-history traits to changes in density suggests that these changes were primarily due to phenotypic plasticity, although the importance of natural and artificial selection should not be discounted. The magnitude of the variation in the traits represents the degree to which the population was able to compensate for overharvest, although the overexploited state of the population at the beginning of the study demonstrates it was not able to fully compensate for this mortality. However, no evidence of depensatory processes was found. This, in combination with the plasticity of the life-history traits, has important implications for the resilience of the population to overharvest. Furthermore, density-dependent growth may have the unintended result of making size-based regulations less conservative at low levels of population abundance, as younger fish, perhaps even immature fish, become vulnerable to harvest. Finally, the

  16. Computational studies of history dependence in nematic liquid crystals in random environments

    NASA Astrophysics Data System (ADS)

    Ranjkesh, Amid; Ambrožič, Milan; Kralj, Samo; Sluckin, Timothy J.

    2014-02-01

    Glassy liquid crystalline systems are expected to show significant history-dependent effects. Two model glassy systems are the RAN and SSS (sprinkled silica spin) lattice models. The RAN model is a Lebwohl-Lasher lattice model with locally coupled nematic spins, together with uncorrelated random anisotropy fields at each site, while the SSS model has a finite concentration of impurity spins frozen in random directions. Here Brownian simulation is used to study the effect of different sample histories in the low temperature regime in a three-dimensional (d =3) model intermediate between SSS and RAN, in which a finite concentration p histories (TQH and FQH, respectively), as well as for temperature-annealed histories (AH). The first two of these limits represent extreme histories encountered in typical experimental studies. Using long-time averages for equilibrated systems, we calculate orientational order parameters and two-point correlation functions. Finite-size scaling was used to determine the range of the orientational ordering, as a function of coupling strength W ,p and sample history. Sample history plays a significant role; for given concentration p, as disorder strength W is increased, TQH systems sustain quasi-long-range order (QLRO) and short-range order (SRO). The data are also consistent with a long-range order (LRO) phase at very low disorder strength. By contrast, for FQH and p ≤0.1, only LRO and QLRO occur within the range of parameters investigated. The crossover between regimes depends on history, but in general, the FQH phase is more ordered than the AH phase, which is more ordered than the TQH phase. However, at temperatures close to the isotropic-nematic phase transition of pure samples

  17. Computational studies of history dependence in nematic liquid crystals in random environments.

    PubMed

    Ranjkesh, Amid; Ambrožič, Milan; Kralj, Samo; Sluckin, Timothy J

    2014-02-01

    Glassy liquid crystalline systems are expected to show significant history-dependent effects. Two model glassy systems are the RAN and SSS (sprinkled silica spin) lattice models. The RAN model is a Lebwohl-Lasher lattice model with locally coupled nematic spins, together with uncorrelated random anisotropy fields at each site, while the SSS model has a finite concentration of impurity spins frozen in random directions. Here Brownian simulation is used to study the effect of different sample histories in the low temperature regime in a three-dimensional (d = 3) model intermediate between SSS and RAN, in which a finite concentration p < p(c) (p(c) the percolation threshold) of frozen spins interacts with neighboring nematic spins with coupling W. Simulations were performed at temperature T ∼ T(NI)/2 (T(NI) the bulk nematic-isotropic transition temperature) for temperature-quenched and field-quenched histories (TQH and FQH, respectively), as well as for temperature-annealed histories (AH). The first two of these limits represent extreme histories encountered in typical experimental studies. Using long-time averages for equilibrated systems, we calculate orientational order parameters and two-point correlation functions. Finite-size scaling was used to determine the range of the orientational ordering, as a function of coupling strength W,p and sample history. Sample history plays a significant role; for given concentration p, as disorder strength W is increased, TQH systems sustain quasi-long-range order (QLRO) and short-range order (SRO). The data are also consistent with a long-range order (LRO) phase at very low disorder strength. By contrast, for FQH and p ≤ 0.1, only LRO and QLRO occur within the range of parameters investigated. The crossover between regimes depends on history, but in general, the FQH phase is more ordered than the AH phase, which is more ordered than the TQH phase. However, at temperatures close to the isotropic-nematic phase transition of

  18. Memory in microbes: quantifying history-Dependent behavior in a bacterium.

    SciTech Connect

    Wolf, Denise M.; Fontaine-Bodin, Lisa; Bischofs, Ilka; Price, Gavin; Keaslin, Jay; Arkin, Adam P.

    2007-11-15

    Memory is usually associated with higher organisms rather than bacteria. However, evidence is mounting that many regulatory networks within bacteria are capable of complex dynamics and multi-stable behaviors that have been linked to memory in other systems. Moreover, it is recognized that bacteria that have experienced different environmental histories may respond differently to current conditions. These"memory" effects may be more than incidental to the regulatory mechanisms controlling acclimation or to the status of the metabolic stores. Rather, they may be regulated by the cell and confer fitness to the organism in the evolutionary game it participates in. Here, we propose that history-dependent behavior is a potentially important manifestation of memory, worth classifying and quantifying. To this end, we develop an information-theory based conceptual framework for measuring both the persistence of memory in microbes and the amount of information about the past encoded in history-dependent dynamics. This method produces a phenomenological measure of cellular memory without regard to the specific cellular mechanisms encoding it. We then apply this framework to a strain of Bacillus subtilis engineered to report on commitment to sporulation and degradative enzyme (AprE) synthesis and estimate the capacity of these systems and growth dynamics to 'remember' 10 distinct cell histories prior to application of a common stressor. The analysis suggests that B. subtilis remembers, both in short and long term, aspects of its cell history, and that this memory is distributed differently among the observables. While this study does not examine the mechanistic bases for memory, it presents a framework for quantifying memory in cellular behaviors and is thus a starting point for studying new questions about cellular regulation and evolutionary strategy.

  19. History-Dependent Excitability as a Single-Cell Substrate of Transient Memory for Information Discrimination

    PubMed Central

    Baroni, Fabiano; Torres, Joaquín J.; Varona, Pablo

    2010-01-01

    Neurons react differently to incoming stimuli depending upon their previous history of stimulation. This property can be considered as a single-cell substrate for transient memory, or context-dependent information processing: depending upon the current context that the neuron “sees” through the subset of the network impinging on it in the immediate past, the same synaptic event can evoke a postsynaptic spike or just a subthreshold depolarization. We propose a formal definition of History-Dependent Excitability (HDE) as a measure of the propensity to firing in any moment in time, linking the subthreshold history-dependent dynamics with spike generation. This definition allows the quantitative assessment of the intrinsic memory for different single-neuron dynamics and input statistics. We illustrate the concept of HDE by considering two general dynamical mechanisms: the passive behavior of an Integrate and Fire (IF) neuron, and the inductive behavior of a Generalized Integrate and Fire (GIF) neuron with subthreshold damped oscillations. This framework allows us to characterize the sensitivity of different model neurons to the detailed temporal structure of incoming stimuli. While a neuron with intrinsic oscillations discriminates equally well between input trains with the same or different frequency, a passive neuron discriminates better between inputs with different frequencies. This suggests that passive neurons are better suited to rate-based computation, while neurons with subthreshold oscillations are advantageous in a temporal coding scheme. We also address the influence of intrinsic properties in single-cell processing as a function of input statistics, and show that intrinsic oscillations enhance discrimination sensitivity at high input rates. Finally, we discuss how the recognition of these cell-specific discrimination properties might further our understanding of neuronal network computations and their relationships to the distribution and functional

  20. History dependence of human muscle-fiber conduction velocity during voluntary isometric contractions.

    PubMed

    McGill, Kevin C; Lateva, Zoia C

    2011-09-01

    The conduction velocity (CV) of a muscle fiber is affected by the fiber's discharge history going back ∼1 s. We investigated this dependence by measuring CV fluctuations during voluntary isometric contractions of the human brachioradialis muscle. We recorded electromyogram (EMG) signals simultaneously from multiple intramuscular electrodes, identified potentials belonging to the same motor unit using EMG decomposition, and estimated the CV of each discharge from the interpotential interval. In 12 of 14 subjects, CV increased by ∼10% during the first second after recruitment and then fluctuated by about ±2% in a way that mirrored the fluctuations in the instantaneous firing rate. The CV profile could be precisely described in terms of the discharge history by a simple mathematical model. In the other two subjects, and one subject retested after cooling the arm, the CV fluctuations were inversely correlated with instantaneous firing rate. In all subjects, CV was additionally affected by very short interdischarge intervals (<25 ms): it was increased in doublets at recruitment, but decreased in doublets during continuous firing and after short interdischarge intervals in doubly innervated fibers. CV also exhibited a slow trend of about -0.05%/s that did not depend on the immediate discharge history. We suggest that measurements of CV fluctuations during voluntary contractions, or during stimulation protocols that involve longer and more complex stimulation patterns than are currently being used, may provide a sensitive approach for estimating the dynamic characteristics of ion channels in the human muscle-fiber membrane. PMID:21565985

  1. History dependence of human muscle-fiber conduction velocity during voluntary isometric contractions

    PubMed Central

    Lateva, Zoia C.

    2011-01-01

    The conduction velocity (CV) of a muscle fiber is affected by the fiber's discharge history going back ∼1 s. We investigated this dependence by measuring CV fluctuations during voluntary isometric contractions of the human brachioradialis muscle. We recorded electromyogram (EMG) signals simultaneously from multiple intramuscular electrodes, identified potentials belonging to the same motor unit using EMG decomposition, and estimated the CV of each discharge from the interpotential interval. In 12 of 14 subjects, CV increased by ∼10% during the first second after recruitment and then fluctuated by about ±2% in a way that mirrored the fluctuations in the instantaneous firing rate. The CV profile could be precisely described in terms of the discharge history by a simple mathematical model. In the other two subjects, and one subject retested after cooling the arm, the CV fluctuations were inversely correlated with instantaneous firing rate. In all subjects, CV was additionally affected by very short interdischarge intervals (<25 ms): it was increased in doublets at recruitment, but decreased in doublets during continuous firing and after short interdischarge intervals in doubly innervated fibers. CV also exhibited a slow trend of about −0.05%/s that did not depend on the immediate discharge history. We suggest that measurements of CV fluctuations during voluntary contractions, or during stimulation protocols that involve longer and more complex stimulation patterns than are currently being used, may provide a sensitive approach for estimating the dynamic characteristics of ion channels in the human muscle-fiber membrane. PMID:21565985

  2. Critical-state model for thin superconductors with history dependent Jc( B)

    NASA Astrophysics Data System (ADS)

    Kulkarni, D. G.; Bhagwat, K. V.; Ravikumar, G.

    2003-08-01

    The peak effect and the accompanying history effects observed in weakly pinned hard type II superconductors have been the focus of attention for the past several years. A phenomenological model that takes into account history dependence in the critical current density was proposed recently to describe these effects. Hall-array measurements of field profiles in the peak region show that they are qualitatively different from those for samples that do not exhibit the peak effect. We present a numerical scheme to calculate the field profiles and dynamic magnetization hysteresis loops for a single crystal platelet sample. We numerically solve time dependent Maxwell’s equations involving curl B and curl E through introduction of an inductance matrix. The E- J relation is assumed as a power law E∼ Ec( J/ Jc) n, where Jc is the critical current density. In this scheme the magnetization loops would be dependent on the sweep rate of the magnetic field as observed in experiments. Further, it also describes the time relaxation of magnetization in a fixed magnetic field. The scheme is first applied to solve the critical state model for the exponential model for Jc( B), and samples such as platelets of a single crystal. We then allow history dependence in Jc( B) and numerically determine current and field profiles. From the current profiles we obtain the envelope magnetization curves and also the minor loops. We find that the field profiles in the peak region show behavior qualitatively similar to that reported in Hall-array measurements. Our calculations indicate that strong demagnetization effects present in a thin sample do not vitiate the main features of the peak effect observed in a bulk sample.

  3. Sense of control under uncertainty depends on people's childhood environment: a life history theory approach.

    PubMed

    Mittal, Chiraag; Griskevicius, Vladas

    2014-10-01

    Past research found that environmental uncertainty leads people to behave differently depending on their childhood environment. For example, economic uncertainty leads people from poor childhoods to become more impulsive while leading people from wealthy childhoods to become less impulsive. Drawing on life history theory, we examine the psychological mechanism driving such diverging responses to uncertainty. Five experiments show that uncertainty alters people's sense of control over the environment. Exposure to uncertainty led people from poorer childhoods to have a significantly lower sense of control than those from wealthier childhoods. In addition, perceptions of control statistically mediated the effect of uncertainty on impulsive behavior. These studies contribute by demonstrating that sense of control is a psychological driver of behaviors associated with fast and slow life history strategies. We discuss the implications of this for theory and future research, including that environmental uncertainty might lead people who grew up poor to quit challenging tasks sooner than people who grew up wealthy. PMID:25133717

  4. Memory in Microbes: Quantifying History-Dependent Behavior in a Bacterium

    SciTech Connect

    Wolf, Denise M.; Fontaine-Bodin, Lisa; Bischofs, Ilka; Price, Gavin; Keasling, Jay; Arkin, Adam P.

    2007-11-15

    Memory is usually associated with higher organisms rather than bacteria. However, evidence is mounting that many regulatory networks within bacteria are capable of complex dynamics and multi-stable behaviors that have been linked to memory in other systems. Moreover, it is recognized that bacteria that have experienced different environmental histories may respond differently to current conditions. These"memory" effects may be more than incidental to the regulatory mechanisms controlling acclimation or to the status of the metabolic stores. Rather, they may be regulated by the cell and confer fitness to the organism in the evolutionary game it participates in. Here, we propose that history-dependent behavior is a potentially important manifestation of memory, worth classifying and quantifying. To this end, we develop an information-theory based conceptual framework for measuring both the persistence of memory in microbes and the amount of information about the past encoded in history-dependent dynamics. This method produces a phenomenologicalmeasure of cellular memory without regard to the specific cellular mechanisms encoding it. We then apply this framework to a strain of Bacillus subtilis engineered to report on commitment to sporulation and degradative enzyme (AprE) synthesisand estimate the capacity of these systems and growth dynamics to"remember" 10 distinct cell histories prior to application of a common stressor. The analysis suggests that B. subtilis remembers, both in short and long term, aspects of its cellhistory, and that this memory is distributed differently among the observables. While this study does not examine the mechanistic bases for memory, it presents a framework for quantifying memory in cellular behaviors and is thus a starting point for studying new questions about cellular regulation and evolutionary strategy.

  5. Experimental evidence for density-dependent regulation and selection on Trinidadian guppy life histories.

    PubMed

    Bassar, Ronald D; Lopez-Sepulcre, Andres; Reznick, David N; Travis, Joseph

    2013-01-01

    Recent study of feedbacks between ecological and evolutionary processes has renewed interest in population regulation and density-dependent selection because they represent black-box descriptions of these feedbacks. The roles of population regulation and density-dependent selection in life-history evolution have received a significant amount of theoretical attention, but there are few empirical examples demonstrating their importance. We address this challenge in natural populations of the Trinidadian guppy (Poecilia reticulata) that differ in their predation regimes. First, we tested whether natural populations of guppies are regulated by density dependence and quantified in which phases of the life cycle the effects of density are important. We found that guppies from low-predation (LP) environments are tightly regulated and that the density-dependent responses disproportionately affected some size classes. Second, we tested whether there are differences in density-dependent selection between guppies from LP or high-predation (HP) environments. We found that the fitness of HP guppies is more sensitive to the depressant effects of density than the fitness of LP guppies. Finally, we used an evolutionary invasion analysis to show that, depending on the effect of density on survival of the HP phenotype, this greater sensitivity of the HP phenotype to density can partially explain the evolution of the LP phenotype. We discuss the relevance of these findings to the study of feedbacks between ecology and evolution. PMID:23234843

  6. History Dependent Magnetoresistance in Lightly Doped LaZxSrxCuO4Thin Films

    SciTech Connect

    Bozovic I.; Shi, X.; Popovic, D.; Panagopoulos, C.; Logvenov, G.; Bollinger, A.T.

    2012-06-01

    The in-plane magnetoresistance (MR) in atomically smooth La{sub 2-x}Sr{sub x}CuO{sub 4} thin films grown by molecular-beam-epitaxy was measured in magnetic fields B up to 9 T over a wide range of temperatures T. The films, with x = 0.03 and x = 0.05, are insulating, and the positive MR emerges at T < 4 K. The positive MR exhibits glassy features, including history dependence and memory, for all orientations of B. The results show that this behavior, which reflects the onset of glassiness in the dynamics of doped holes, is a robust feature of the insulating state.

  7. History of sexual, emotional or physical abuse and psychiatric comorbidity in substance-dependent patients.

    PubMed

    Daigre, Constanza; Rodríguez-Cintas, Laia; Tarifa, Núria; Rodríguez-Martos, Lola; Grau-López, Lara; Berenguer, Marta; Casas, Miguel; Roncero, Carlos

    2015-10-30

    Sexual, emotional or physical abuse history is a risk factor for mental disorders in addicted patients. However, the relationship between addiction and abuse lifespan is not well known. This study aims to compare clinical and psychopathological features of addicted patients according to the experience of abuse and to the number of different types of abuse suffered. Bivariate and multivariate analyses were conducted. 512 addicted patients seeking treatment were included, 45.9% reported abuse throughout life (38.9% emotional, 22.3% physical and 13.5% sexual abuse). It was found that female gender; depressive symptoms and borderline personality disorder were independently associated with history of any abuse throughout life. As well, it was found that 14% have been suffered from all three types of abuse (sexual, emotional and physical), 34.5% from two and 55.5% from one type. Female gender and borderline personality disorder were independently associated independently with a greater number of different types of abuse. Results suggest that history of abuse is frequent among substance-dependent patients and these experiences are more prevalent in women and are associated with more psychiatric comorbidity. PMID:26279128

  8. Multiscale simulation of history-dependent flow in entangled polymer melts

    NASA Astrophysics Data System (ADS)

    Murashima, T.; Taniguchi, T.

    2011-10-01

    Predicting the flow of an entangled polymer melt is still difficult because of its multiscale characteristics. We have developed a novel multiscale simulation technique to investigate the history-dependent flow behavior of entangled polymer melts. The technique involves using a smoothed particle hydrodynamics simulation that is coupled at each fluid element to microscopic simulators that can accurately account for the dynamics of entangled polymers. The multiscale simulation is used to investigate the flow of an entangled polymer melt around a cylindrical obstacle subject to periodic boundary conditions. It is found that the macroscopic flow behavior is dependent on the history of the microscopic states of the polymers and that this memory causes nonlinear behavior even in the regions where the local Weissenberg number defined using the local strain-rate is less than unity. The spatial distribution of the entanglements langZrang suggests that, in a region around the obstacle, a slight depletion of the entanglements is observed and that this region broadens along the downstream direction. The totality of the presented results suggests that we have succeeded in describing the entangled polymer melt flow without using any constitutive equation.

  9. An exact solution for the history-dependent material and delamination behavior of laminated plates subjected to cylindrical bending

    SciTech Connect

    Williams, Todd O

    2009-01-01

    The exact solution for the history-dependent behavior of laminated plates subjected to cylindrical bending is presented. The solution represents the extension of Pagano's solution to consider arbitrary types of constitutive behaviors for the individual lamina as well as arbitrary types of cohesive zones models for delamination behavior. Examples of the possible types of material behavior are plasticity, viscoelasticity, viscoplasticity, and damaging. Examples of possible CZMs that can be considered are linear, nonlinear hardening, as well as nonlinear with softening. The resulting solution is intended as a benchmark solution for considering the predictive capabilities of different plate theories. Initial results are presented for several types of history-dependent material behaviors. It is shown that the plate response in the presence of history-dependent behaviors can differ dramatically from the elastic response. These results have strong implications for what constitutes an appropriate plate theory for modeling such behaviors.

  10. Thermal-history dependent magnetoelastic transition in (Mn,Fe){sub 2}(P,Si)

    SciTech Connect

    Miao, X. F. Dijk, N. H. van; Brück, E.; Caron, L.; Gercsi, Z.; Daoud-Aladine, A.

    2015-07-27

    The thermal-history dependence of the magnetoelastic transition in (Mn,Fe){sub 2}(P,Si) compounds has been investigated using high-resolution neutron diffraction. As-prepared samples display a large difference in paramagnetic-ferromagnetic (PM-FM) transition temperature compared to cycled samples. The initial metastable state transforms into a lower-energy stable state when the as-prepared sample crosses the PM-FM transition for the first time. This additional transformation is irreversible around the transition temperature and increases the energy barrier which needs to be overcome through the PM-FM transition. Consequently, the transition temperature on first cooling is found to be lower than on subsequent cycles characterizing the so-called “virgin effect.” High-temperature annealing can restore the cycled sample to the high-temperature metastable state, which leads to the recovery of the virgin effect. A model is proposed to interpret the formation and recovery of the virgin effect.

  11. Measuring Temperaturelike State Variables in History-Dependent Jammed Granular Systems

    NASA Astrophysics Data System (ADS)

    Bililign, Ephraim; Daniels, Karen

    Granular systems are athermal, thus a complete statistical mechanics framework must be based on a set of macroscopic state variables which excludes temperature. One leading theory incorporates a stress-based ensemble, and predicts a Boltzmann-like distribution of the force-moment tensor with respect to the conjugate, temperature-like variable, angoricity. We experimentally test this theory on a static, bidisperse, two-dimensional packing of discs. Basal friction is eliminated by floating the discs on a sub-fluidizing upflow of air, and the packings are subjected to either uniaxial compression or simple shear. We simultaneously measure the contact forces acting on each disc using photoelasticity. These measurements are repeated over many configurations of discs by dilating and rearranging the system, and the angoricity is computed as a function of the confining pressure. In particular, we test the predicted linear relationship between angoricity and pressure. Comparison to prior results and numerical simulations also suggests a history-dependent angoricity, an undesirable feature in the proposed state variable.

  12. Understanding scaling through history-dependent processes with collapsing sample space

    PubMed Central

    Corominas-Murtra, Bernat; Hanel, Rudolf; Thurner, Stefan

    2015-01-01

    History-dependent processes are ubiquitous in natural and social systems. Many such stochastic processes, especially those that are associated with complex systems, become more constrained as they unfold, meaning that their sample space, or their set of possible outcomes, reduces as they age. We demonstrate that these sample-space-reducing (SSR) processes necessarily lead to Zipf’s law in the rank distributions of their outcomes. We show that by adding noise to SSR processes the corresponding rank distributions remain exact power laws, p(x)∼x−λ, where the exponent directly corresponds to the mixing ratio of the SSR process and noise. This allows us to give a precise meaning to the scaling exponent in terms of the degree to which a given process reduces its sample space as it unfolds. Noisy SSR processes further allow us to explain a wide range of scaling exponents in frequency distributions ranging from α=2 to ∞. We discuss several applications showing how SSR processes can be used to understand Zipf’s law in word frequencies, and how they are related to diffusion processes in directed networks, or aging processes such as in fragmentation processes. SSR processes provide a new alternative to understand the origin of scaling in complex systems without the recourse to multiplicative, preferential, or self-organized critical processes. PMID:25870294

  13. Understanding scaling through history-dependent processes with collapsing sample space.

    PubMed

    Corominas-Murtra, Bernat; Hanel, Rudolf; Thurner, Stefan

    2015-04-28

    History-dependent processes are ubiquitous in natural and social systems. Many such stochastic processes, especially those that are associated with complex systems, become more constrained as they unfold, meaning that their sample space, or their set of possible outcomes, reduces as they age. We demonstrate that these sample-space-reducing (SSR) processes necessarily lead to Zipf's law in the rank distributions of their outcomes. We show that by adding noise to SSR processes the corresponding rank distributions remain exact power laws, p(x) ~ x(-λ), where the exponent directly corresponds to the mixing ratio of the SSR process and noise. This allows us to give a precise meaning to the scaling exponent in terms of the degree to which a given process reduces its sample space as it unfolds. Noisy SSR processes further allow us to explain a wide range of scaling exponents in frequency distributions ranging from α = 2 to ∞. We discuss several applications showing how SSR processes can be used to understand Zipf's law in word frequencies, and how they are related to diffusion processes in directed networks, or aging processes such as in fragmentation processes. SSR processes provide a new alternative to understand the origin of scaling in complex systems without the recourse to multiplicative, preferential, or self-organized critical processes. PMID:25870294

  14. Single DNA molecule jamming and history-dependent dynamics during motor-driven viral packaging

    NASA Astrophysics Data System (ADS)

    Keller, Nicholas; Grimes, Shelley; Jardine, Paul J.; Smith, Douglas E.

    2016-08-01

    In many viruses, molecular motors forcibly pack single DNA molecules to near-crystalline density into ~50-100 nm prohead shells. Unexpectedly, we found that packaging frequently stalls in conditions that induce net attractive DNA-DNA interactions. Here, we present findings suggesting that this stalling occurs because the DNA undergoes a nonequilibrium jamming transition analogous to that observed in many soft-matter systems, such as colloidal and granular systems. Experiments in which conditions are changed during packaging to switch DNA-DNA interactions between purely repulsive and net attractive reveal strongly history-dependent dynamics. An abrupt deceleration is usually observed before stalling, indicating that a transition in DNA conformation causes an abrupt increase in resistance. Our findings suggest that the concept of jamming can be extended to a single polymer molecule. However, compared with macroscopic samples of colloidal particles we find that single DNA molecules jam over a much larger range of densities. We attribute this difference to the nanoscale system size, consistent with theoretical predictions for jamming of attractive athermal particles.

  15. Decreased Sensitivity to Long-Distance Dependencies in Children with a History of Specific Language Impairment: Electrophysiological Evidence

    ERIC Educational Resources Information Center

    Purdy, J. D.; Leonard, Laurence B.; Weber-Fox, Christine; Kaganovich, Natalya

    2014-01-01

    Purpose: One possible source of tense and agreement limitations in children with specific language impairment (SLI) is a weakness in appreciating structural dependencies that occur in many sentences in the input. This possibility was tested in the present study. Method: Children with a history of SLI (H-SLI; n = 12; M = 9;7 [years;months]) and…

  16. THE MASS-DEPENDENT STAR FORMATION HISTORIES OF DISK GALAXIES: INFALL MODEL VERSUS OBSERVATIONS

    SciTech Connect

    Chang, R. X.; Hou, J. L.; Shen, S. Y.; Shu, C. G.

    2010-10-10

    We introduce a simple model to explore the star formation histories of disk galaxies. We assume that the disk originate and grows by continuous gas infall. The gas infall rate is parameterized by the Gaussian formula with one free parameter: the infall-peak time t{sub p} . The Kennicutt star formation law is adopted to describe how much cold gas turns into stars. The gas outflow process is also considered in our model. We find that, at a given galactic stellar mass M{sub *}, the model adopting a late infall-peak time t{sub p} results in blue colors, low-metallicity, high specific star formation rate (SFR), and high gas fraction, while the gas outflow rate mainly influences the gas-phase metallicity and star formation efficiency mainly influences the gas fraction. Motivated by the local observed scaling relations, we 'construct' a mass-dependent model by assuming that the low-mass galaxy has a later infall-peak time t{sub p} and a larger gas outflow rate than massive systems. It is shown that this model can be in agreement with not only the local observations, but also with the observed correlations between specific SFR and galactic stellar mass SFR/M{sub *} {approx} M{sub *} at intermediate redshifts z < 1. Comparison between the Gaussian-infall model and the exponential-infall model is also presented. It shows that the exponential-infall model predicts a higher SFR at early stage and a lower SFR later than that of Gaussian infall. Our results suggest that the Gaussian infall rate may be more reasonable in describing the gas cooling process than the exponential infall rate, especially for low-mass systems.

  17. Opposite Cannabis-Cognition Associations in Psychotic Patients Depending on Family History.

    PubMed

    González-Pinto, Ana; González-Ortega, Itxaso; Alberich, Susana; Ruiz de Azúa, Sonia; Bernardo, Miguel; Bioque, Miquel; Cabrera, Bibiana; Corripio, Iluminada; Arango, Celso; Lobo, Antonio; Sánchez-Torres, Ana M; Cuesta, Manuel J

    2016-01-01

    The objective of this study is to investigate cognitive performance in a first-episode psychosis sample, when stratifying the interaction by cannabis use and familial or non-familial psychosis. Hierarchical-regression models were used to analyse this association in a sample of 268 first-episode psychosis patients and 237 controls. We found that cannabis use was associated with worse working memory, regardless of family history. However, cannabis use was clearly associated with worse cognitive performance in patients with no family history of psychosis, in cognitive domains including verbal memory, executive function and global cognitive index, whereas cannabis users with a family history of psychosis performed better in these domains. The main finding of the study is that there is an interaction between cannabis use and a family history of psychosis in the areas of verbal memory, executive function and global cognition: that is, cannabis use is associated with a better performance in patients with a family history of psychosis and a worse performance in those with no family history of psychosis. In order to confirm this hypothesis, future research should explore the actual expression of the endocannabinoid system in patients with and without a family history of psychosis. PMID:27513670

  18. Opposite Cannabis-Cognition Associations in Psychotic Patients Depending on Family History

    PubMed Central

    González-Pinto, Ana; González-Ortega, Itxaso; Alberich, Susana; Ruiz de Azúa, Sonia; Bernardo, Miguel; Bioque, Miquel; Cabrera, Bibiana; Corripio, Iluminada; Arango, Celso; Lobo, Antonio; Sánchez-Torres, Ana M.; Cuesta, Manuel J.

    2016-01-01

    The objective of this study is to investigate cognitive performance in a first-episode psychosis sample, when stratifying the interaction by cannabis use and familial or non-familial psychosis. Hierarchical-regression models were used to analyse this association in a sample of 268 first-episode psychosis patients and 237 controls. We found that cannabis use was associated with worse working memory, regardless of family history. However, cannabis use was clearly associated with worse cognitive performance in patients with no family history of psychosis, in cognitive domains including verbal memory, executive function and global cognitive index, whereas cannabis users with a family history of psychosis performed better in these domains. The main finding of the study is that there is an interaction between cannabis use and a family history of psychosis in the areas of verbal memory, executive function and global cognition: that is, cannabis use is associated with a better performance in patients with a family history of psychosis and a worse performance in those with no family history of psychosis. In order to confirm this hypothesis, future research should explore the actual expression of the endocannabinoid system in patients with and without a family history of psychosis. PMID:27513670

  19. An investigation of the effects of history dependent damage in time dependent fracture mechanics; Phases I, II, and one half of Phase III - variable load conditions. Progress report

    SciTech Connect

    Brust, F.W.; Krishnaswamy, P.; Majumdar, B.S.

    1993-10-15

    The demands for structural systems to perform reliably under severe temperatures and load conditions continue to increase. These demands will continue with the development of advanced power generation methods, for aging nuclear and fossil fueled power plants, and for future aerospace applications. An understanding of the high-temperature creep crack growth process, which is a frequent failure mechanism in these structures, is important. Many investigations which have appeared to date are concerned with creep crack growth which occurs under a constant load and temperature. However, most structural components experience complicated load histories. The history of degradation and damage which accumulates at the crack tip is greatly influenced by these transients. This program aims at gaining an understanding of the history dependent high temperature failure process through a combined experimental and analytical effort. The development of a useful predictive methodology for characterizing this process is being undertaken.

  20. Carbon sequestration potential of grazed pasture depends on prior management history

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grazed pastures are often assumed to be net sinks for removing carbon dioxide from the atmosphere and thus, are promoted as a management practice that can help mitigate climate change. The ability to serve as a C sink is especially pronounced following a history of tillage and row crop production. I...

  1. Maternal investment mediates offspring life history variation with context-dependent fitness consequences.

    PubMed

    Moore, Michael P; Landberg, Tobias; Whiteman, Howard H

    2015-09-01

    Maternal effects, such as per capita maternal investment, often interact with environmental conditions to strongly affect traits expressed early in ontogeny. However, their impact on adult life history traits and fitness components is relatively unknown. Theory predicts that lower per capita maternal investment will have strong fitness costs when the offspring develop in unfavorable conditions, yet few studies have experimentally manipulated per capita maternal investment and followed offspring through adulthood. We used a surgical embryonic yolk removal technique to investigate how per capita maternal investment interacted with an important ecological factor, larval density, to mediate offspring life history traits through reproductive maturity in an amphibian, Ambystoma talpoideum. We predicted that increased larval density would reinforce the life history variation induced by differences in per capita investment (i.e., Controls vs. Reduced Yolk), with Reduced larvae ultimately expressing traits associated with lower fitness than Controls when raised at high densities. We found that Reduced individuals were initially smaller and more developed, caught up in size to Controls within the first month of the larval stage, but were smaller at the end of the larval stage in low densities. Reduced individuals also were more likely to undergo metamorphosis at high densities and mature 'females invested in more eggs for their body sizes than Controls. Together, our results do not support our hypothesis, but instead indicate that Reduced individuals express traits associated with higher fitness when they develop in high-density environments, but lower fitness in low-density environments. The observed life history and fitness patterns are consistent with the "maternal match" hypothesis, which predicts that when the maternal environment (e.g., high density) results in phenotypic variation that is transmitted to the offspring (e.g., reduced per capita yolk investment), and

  2. Response of single bacterial cells to stress gives rise to complex history dependence at the population level.

    PubMed

    Mathis, Roland; Ackermann, Martin

    2016-04-12

    Most bacteria live in ever-changing environments where periods of stress are common. One fundamental question is whether individual bacterial cells have an increased tolerance to stress if they recently have been exposed to lower levels of the same stressor. To address this question, we worked with the bacterium Caulobacter crescentus and asked whether exposure to a moderate concentration of sodium chloride would affect survival during later exposure to a higher concentration. We found that the effects measured at the population level depended in a surprising and complex way on the time interval between the two exposure events: The effect of the first exposure on survival of the second exposure was positive for some time intervals but negative for others. We hypothesized that the complex pattern of history dependence at the population level was a consequence of the responses of individual cells to sodium chloride that we observed: (i) exposure to moderate concentrations of sodium chloride caused delays in cell division and led to cell-cycle synchronization, and (ii) whether a bacterium would survive subsequent exposure to higher concentrations was dependent on the cell-cycle state. Using computational modeling, we demonstrated that indeed the combination of these two effects could explain the complex patterns of history dependence observed at the population level. Our insight into how the behavior of single cells scales up to processes at the population level provides a perspective on how organisms operate in dynamic environments with fluctuating stress exposure. PMID:26960998

  3. Response of single bacterial cells to stress gives rise to complex history dependence at the population level

    PubMed Central

    Mathis, Roland; Ackermann, Martin

    2016-01-01

    Most bacteria live in ever-changing environments where periods of stress are common. One fundamental question is whether individual bacterial cells have an increased tolerance to stress if they recently have been exposed to lower levels of the same stressor. To address this question, we worked with the bacterium Caulobacter crescentus and asked whether exposure to a moderate concentration of sodium chloride would affect survival during later exposure to a higher concentration. We found that the effects measured at the population level depended in a surprising and complex way on the time interval between the two exposure events: The effect of the first exposure on survival of the second exposure was positive for some time intervals but negative for others. We hypothesized that the complex pattern of history dependence at the population level was a consequence of the responses of individual cells to sodium chloride that we observed: (i) exposure to moderate concentrations of sodium chloride caused delays in cell division and led to cell-cycle synchronization, and (ii) whether a bacterium would survive subsequent exposure to higher concentrations was dependent on the cell-cycle state. Using computational modeling, we demonstrated that indeed the combination of these two effects could explain the complex patterns of history dependence observed at the population level. Our insight into how the behavior of single cells scales up to processes at the population level provides a perspective on how organisms operate in dynamic environments with fluctuating stress exposure. PMID:26960998

  4. History Dependence of the Vortex Lattice Rotation in the B-phase of UPt3 with H ∥ c

    NASA Astrophysics Data System (ADS)

    Avers, K. E.; Eskildsen, M. R.; Halperin, W. P.; Gannon, W. J.; Gavilano, J. L.; Nagy, G.; Gasser, U.

    The unconventional superconductor UPt3 is widely believed to be a triplet superconductor, where the low temperature superconducting B-phase is a chiral state. We have performed small angle neutron scattering (SANS) from the vortex lattice (VL) in UPt3 at the Paul Scherrer Institute with the magnetic field parallel to the hexagonal c-axis in the 0.5 T to 0.9 T range. The diffraction pattern of the VL rotates away from a high symmetry direction producing two domains of different orientation. Our field dependent measurements show a subtle magnetic field history dependence of this orientation; VLs prepared with the magnetic field parallel or anti-parallel with respect to the angular momentum from the circulating screening currents show different field-history dependence. These results suggest a coupling of a chiral superconducting order parameter with the applied magnetic field. US DOE, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Awards DE-FG02-10ER46783 (University of Notre Dame; neutron scattering) and DE-FG02-05ER46248 (Northwestern University; crystal growth, characterization, neutron.

  5. Sweet preference, sugar addiction and the familial history of alcohol dependence: shared neural pathways and genes.

    PubMed

    Fortuna, Jeffrey L

    2010-06-01

    Contemporary research has shown that a high number of alcohol-dependent and other drug-dependent individuals have a sweet preference, specifically for foods with a high sucrose concentration. Moreover, both human and animal studies have demonstrated that in some brains the consumption of sugar-rich foods or drinks primes the release of euphoric endorphins and dopamine within the nucleus accumbens, in a manner similar to some drugs of abuse. The neurobiological pathways of drug and "sugar addiction" involve similar neural receptors, neurotransmitters, and hedonic regions in the brain. Craving, tolerance, withdrawal and sensitization have been documented in both human and animal studies. In addition, there appears to be cross sensitization between sugar addiction and narcotic dependence in some individuals. It has also been observed that the biological children of alcoholic parents, particularly alcoholic fathers, are at greater risk to have a strong sweet preference, and this may manifest in some with an eating disorder. In the last two decades research has noted that specific genes may underlie the sweet preference in alcohol- and drug-dependent individuals, as well as in biological children of paternal alcoholics. There also appears to be some common genetic markers between alcohol dependence, bulimia, and obesity, such as the A1 allele gene and the dopamine 2 receptor gene. PMID:20648910

  6. Density-dependent processes in the life history of fishes: evidence from laboratory populations of zebrafish Danio rerio.

    PubMed

    Hazlerigg, Charles R E; Lorenzen, Kai; Thorbek, Pernille; Wheeler, James R; Tyler, Charles R

    2012-01-01

    Population regulation is fundamental to the long-term persistence of populations and their responses to harvesting, habitat modification, and exposure to toxic chemicals. In fish and other organisms with complex life histories, regulation may involve density dependence in different life-stages and vital rates. We studied density dependence in body growth and mortality through the life-cycle of laboratory populations of zebrafish Danio rerio. When feed input was held constant at population-level (leading to resource limitation), body growth was strongly density-dependent in the late juvenile and adult phases of the life-cycle. Density dependence in mortality was strong during the early juvenile phase but declined thereafter and virtually ceased prior to maturation. Provision of feed in proportion to individual requirements (easing resource limitation) removed density dependence in growth and substantially reduced density dependence in mortality, thus indicating that 'bottom-up' effects act on growth as well as mortality, but most strongly on growth. Both growth and mortality played an important role in population regulation, with density-dependent growth having the greater impact on population biomass while mortality had the greatest impact on numbers. We demonstrate a clear ontogenic pattern of change in density-dependent processes within populations of a very small (maximum length 5 mm) fish, maintained in constant homogeneous laboratory conditions. The patterns are consistent with those distilled from studies on wild fish populations, indicating the presence of broad ontogenic patterns in density-dependent processes that are invariant to maximum body size and hold in homogeneous laboratory, as well as complex natural environments. PMID:22655056

  7. Bird assemblage vulnerability depends on the diversity and biogeographic histories of islands.

    PubMed

    Weeks, Brian C; Gregory, Nichar; Naeem, Shahid

    2016-09-01

    Biodiversity is widely acknowledged to influence the magnitude and stability of a large array of ecosystem properties, with biodiverse systems thought to be more functionally robust. As such, diverse systems may be safer harbors for vulnerable species, resulting in a positive association between biodiversity and the collective vulnerability of species in an assemblage, or "assemblage vulnerability." We find that, for 35 islands across Northern Melanesia, bird assemblage vulnerability and biodiversity are positively associated. This relationship is highly contingent on Pleistocene connectivity, suggesting that biogeographic history-a factor often overlooked in biodiversity and ecosystem-functioning studies-may influence contemporary ecological processes. In the face of biodiversity loss attributable to anthropogenic drivers, reduced ecosystem functioning may erode the safe harbors of vulnerable assemblages. Paradoxically, these results suggest that biodiverse systems, as more robust systems, may experience greater biodiversity loss over ecological time because they harbor more vulnerable species accumulated over evolutionary time. PMID:27551095

  8. A Short History of cGMP, Guanylyl Cyclases, and cGMP-Dependent Protein Kinases

    PubMed Central

    Kots, Alexander Y.; Martin, Emil; Sharina, Iraida G.

    2014-01-01

    Here, we review the early studies on cGMP, guanylyl cyclases, and cGMP-dependent protein kinases to facilitate understanding of development of this exciting but complex field of research encompassing pharmacology, biochemistry, physiology, and molecular biology of these important regulatory molecules. PMID:19089322

  9. Committee Opinion No. 659: The Use of Vaginal Estrogen in Women With a History of Estrogen-Dependent Breast Cancer.

    PubMed

    2016-03-01

    Cancer treatment should address female-specific survivorship issues, including the hypoestrogenic- related adverse effects of cancer therapies or of natural menopause in survivors. Systemic and vaginal estrogen are widely used for symptomatic relief of vasomotor symptoms, sexual dysfunction, and lower urinary tract infections in the general population. However, given that some types of cancer are hormone sensitive, there are safety concerns about the use of local hormone therapy in women who currently have breast cancer or have a history of breast cancer. Nonhormonal approaches are the first-line choices for managing urogenital symptoms or atrophy-related urinary symptoms experienced by women during or after treatment for breast cancer. Among women with a history of estrogen-dependent breast cancer who are experiencing urogenital symptoms, vaginal estrogen should be reserved for those patients who are unresponsive to nonhormonal remedies. The decision to use vaginal estrogen may be made in coordination with a woman's oncologist. Additionally, it should be preceded by an informed decision-making and consent process in which the woman has the information and resources to consider the benefits and potential risks of low-dose vaginal estrogen. Data do not show an increased risk of cancer recurrence among women currently undergoing treatment for breast cancer or those with a personal history of breast cancer who use vaginal estrogen to relieve urogenital symptoms. PMID:26901334

  10. What shall I do now? State-dependent variations of life-history traits with aging in Wandering Albatrosses.

    PubMed

    Pardo, Deborah; Barbraud, Christophe; Weimerskirch, Henri

    2014-02-01

    Allocation decisions depend on an organism's condition which can change with age. Two opposite changes in life-history traits are predicted in the presence of senescence: either an increase in breeding performance in late age associated with terminal investment or a decrease due to either life-history trade-offs between current breeding and future survival or decreased efficiency at old age. Age variation in several life-history traits has been detected in a number of species, and demographic performances of individuals in a given year are influenced by their reproductive state the previous year. Few studies have, however, examined state-dependent variation in life-history traits with aging, and they focused mainly on a dichotomy of successful versus failed breeding and non-breeding birds. Using a 50-year dataset on the long-lived quasi-biennial breeding wandering albatross, we investigated variations in life-history traits with aging according to a gradient of states corresponding to potential costs of reproduction the previous year (in ascending order): non-breeding birds staying at sea or present at breeding grounds, breeding birds that failed early, late or were successful. We used multistate models to study survival and decompose reproduction into four components (probabilities of return, breeding, hatching, and fledging), while accounting for imperfect detection. Our results suggest the possible existence of two strategies in the population: strict biennial breeders that exhibited almost no reproductive senescence and quasi-biennial breeders that showed an increased breeding frequency with a strong and moderate senescence on hatching and fledging probabilities, respectively. The patterns observed on survival were contrary to our predictions, suggesting an influence of individual quality rather than trade-offs between reproduction and survival at late ages. This work represents a step further into understanding the evolutionary ecology of senescence and its

  11. What shall I do now? State-dependent variations of life-history traits with aging in Wandering Albatrosses

    PubMed Central

    Pardo, Deborah; Barbraud, Christophe; Weimerskirch, Henri

    2014-01-01

    Allocation decisions depend on an organism's condition which can change with age. Two opposite changes in life-history traits are predicted in the presence of senescence: either an increase in breeding performance in late age associated with terminal investment or a decrease due to either life-history trade-offs between current breeding and future survival or decreased efficiency at old age. Age variation in several life-history traits has been detected in a number of species, and demographic performances of individuals in a given year are influenced by their reproductive state the previous year. Few studies have, however, examined state-dependent variation in life-history traits with aging, and they focused mainly on a dichotomy of successful versus failed breeding and non-breeding birds. Using a 50-year dataset on the long-lived quasi-biennial breeding wandering albatross, we investigated variations in life-history traits with aging according to a gradient of states corresponding to potential costs of reproduction the previous year (in ascending order): non-breeding birds staying at sea or present at breeding grounds, breeding birds that failed early, late or were successful. We used multistate models to study survival and decompose reproduction into four components (probabilities of return, breeding, hatching, and fledging), while accounting for imperfect detection. Our results suggest the possible existence of two strategies in the population: strict biennial breeders that exhibited almost no reproductive senescence and quasi-biennial breeders that showed an increased breeding frequency with a strong and moderate senescence on hatching and fledging probabilities, respectively. The patterns observed on survival were contrary to our predictions, suggesting an influence of individual quality rather than trade-offs between reproduction and survival at late ages. This work represents a step further into understanding the evolutionary ecology of senescence and its

  12. History dependence of the magnetic properties of single-crystal Fe1 -xCoxSi

    NASA Astrophysics Data System (ADS)

    Bauer, A.; Garst, M.; Pfleiderer, C.

    2016-06-01

    We report the magnetization, ac susceptibility, and specific heat of optically float-zoned single crystals of Fe1 -xCoxSi , 0.20 ≤x ≤0.50 . We determine the magnetic phase diagrams for all major crystallographic directions and cooling histories. After zero-field cooling, the phase diagrams resemble that of the archetypal stoichiometric cubic chiral magnet MnSi. Besides the helical and conical state, we observe a pocket of skyrmion lattice phase just below the helimagnetic ordering temperature. At the phase boundaries between these states evidence for slow dynamics is observed. When the sample is cooled in small magnetic fields, the phase pocket of skyrmion lattice may persist metastably down to the lowest temperatures. Taken together with the large variation in the transition temperatures, transition fields, and helix wavelength as a function of the composition, this hysteresis identifies Fe1 -xCoxSi as an ideal material for future experiments exploring, for instance, the topological unwinding of the skyrmion lattice.

  13. Field-History Dependence of the Superconducting Transition Temperature in Erbium/Niobium Bilayers

    NASA Astrophysics Data System (ADS)

    Witt, James; Satchell, Nathan; Langridge, Sean; Burnell, Gavin

    Recently, there has been much interest in a new class of superconducting (S) spintronic devices based upon hybrid S/F (ferromagnet) heterostructures. The prototypical super-spintronic device is the superconducting spin valve (SSV), within which the critical temperature (Tc) of an S layer can be controlled by the relative orientation of two or more F layers. Such manipulation of the F layers requires careful engineering of the heterostructure and the rotation of the structure with respect to an applied magnetic field. Here, we show that such control over Tc is also possible in a simple S/F bilayer. By manipulating the remenant magnetic state of a thin Er layer - which is proximity coupled to a Nb S layer - we are able to demonstrate a high level of control over the Tc of the Nb (which is measured in zero field). The shifts in Tc are comparable in size to the largest seen in the SSV and are manipulated using solely the field history. The system can be reset by warming the sample through the Er Curie temperature (approximately 20 K). Our results are of particular interest due to the simplicity of both the bilayer and the measurement geometry in comparison to the SSV.

  14. Effect of yohimbine on reinstatement of operant responding in rats is dependent on cue contingency but not food reward history.

    PubMed

    Chen, Yu-Wei; Fiscella, Kimberly A; Bacharach, Samuel Z; Tanda, Gianluigi; Shaham, Yavin; Calu, Donna J

    2015-07-01

    Yohimbine is an alpha-2 adrenoceptor antagonist that has been used in numerous studies as a pharmacological stressor in rodents, monkeys and humans. Recently, yohimbine has become the most common stress manipulation in studies on reinstatement of drug and food seeking. However, the wide range of conditions under which yohimbine promotes reward seeking is significantly greater than that of stressors like intermittent footshock. Here, we addressed two fundamental questions regarding yohimbine's effect on reinstatement of reward seeking: (1) whether the drug's effect on operant responding is dependent on previous reward history or cue contingency, and (2) whether yohimbine is aversive or rewarding under conditions typically used in reinstatement studies. We also used in vivo microdialysis to determine yohimbine's effect on dopamine levels in nucleus accumbens (NAc) and medial prefrontal cortex (mPFC). We found that the magnitude of yohimbine-induced (0.5, 1.0, 2.0 mg/kg) operant responding during the reinstatement tests was critically dependent on the contingency between lever pressing and discrete tone-light cue delivery but not the previous history with food reward during training. We also found that yohimbine (2 mg/kg) did not cause conditioned place aversion. Finally, we found that yohimbine modestly increased dopamine levels in mPFC but not NAc. Results suggest that yohimbine's effects on operant responding in reinstatement studies are likely independent of the history of contingent self-administration of food or drug rewards and may not be related to the commonly assumed stress-like effects of yohimbine. PMID:25065697

  15. Effect of yohimbine on reinstatement of operant responding in rats is dependent on cue contingency but not food reward history

    PubMed Central

    Chen, Yu-Wei; Fiscella, Kimberly A.; Bacharach, Samuel Z.; Tanda, Gianluigi; Shaham, Yavin; Calu, Donna J.

    2014-01-01

    Yohimbine is an alpha-2 adrenoceptor antagonist that has been used in numerous studies as a pharmacological stressor in rodents, monkeys, and humans. Recently, yohimbine has become the most common stress manipulation in studies on reinstatement of drug and food seeking. However, the wide range of conditions under which yohimbine promotes reward seeking is significantly greater than that of stressors like intermittent footshock. Here we addressed two fundamental questions regarding yohimbine’s effect on reinstatement of reward seeking: (1) whether the drug’s effect on operant responding is dependent on previous reward history or cue contingency, and (2) whether yohimbine is aversive or rewarding under conditions typically used in reinstatement studies. We also used in vivo microdialysis to determine yohimbine’s effect on dopamine levels in nucleus accumbens (NAc) and medial prefrontal cortex (mPFC). We found that the magnitude of yohimbine-induced (0.5, 1.0, 2.0 mg/kg) operant responding during the reinstatement tests was critically dependent on the contingency between lever-pressing and discrete tone-light cue delivery but not the previous history with food reward during training. We also found that yohimbine (2 mg/kg) did not cause conditioned place aversion. Finally, we found that yohimbine modestly increased dopamine levels in mPFC but not NAc. Results suggest that yohimbine’s effects on operant responding in reinstatement studies are likely independent of the history of contingent self-administration of food or drug rewards and may not be related to the commonly assumed stress-like effects of yohimbine. PMID:25065697

  16. Cascading life-history interactions: alternative density-dependent pathways drive recruitment dynamics in a freshwater fish.

    PubMed

    Vandenbos, Rena E; Tonn, William M; Boss, Shelly M

    2006-07-01

    Although density-dependent mechanisms in early life-history are important regulators of recruitment in many taxa, consequences of such mechanisms on other life-history stages are poorly understood. To examine interacting and cascading effects of mechanisms acting on different life-history stages, we stocked experimental ponds with fathead minnow (Pimephales promelas) at two different densities. We quantified growth and survival of the stocked fish, the eggs they produced, and the resulting offspring during their first season of life. Per-capita production and survival of eggs were inversely related to density of stocked fish; significant egg cannibalism by stocked minnows resulted in initial young-of-the-year (YOY) densities that were inversely related to adult densities. Subsequent growth and survival of YOY were then inversely related to these initial YOY densities, and survival of YOY was selective for larger fish. Because of these compensatory processes in the egg and YOY stages, treatments did not differ in YOY abundance and mean size at the end of the growing season. Because of differences in the intensity of size-selective mortality, however, variation in end-of season sizes of YOY was strongly (and inversely) related to densities of stocked fish. When mortality was severe in the egg stage (high densities of stocked fish), final YOY size distributions were more variable than when the dominant mortality was size-selective in the YOY stage (low stocked fish densities). These differences in size variation could have subsequent recruitment consequences, as overwinter survival is typically selective for YOY fish larger than a critical threshold size. Density-dependent effects on a given life stage are not independent, but will be influenced by earlier stages; alternative recruitment pathways can result when processes at earlier stages differ in magnitude or selectivity. Appreciation of these cascading effects should enhance our overall understanding of the

  17. Smoking History, Nicotine Dependence, and Changes in Craving and Mood during Short-Term Smoking Abstinence in Alcohol Dependent vs. Control Smokers

    PubMed Central

    Heffner, Jaimee L.; Mingione, Carolyn; Blom, Thomas J.; Anthenelli, Robert M.

    2010-01-01

    Objective The goal of this study was to compare lifetime cigarette smoking, severity of nicotine dependence, and subjective effects of short-term tobacco abstinence in abstinent alcohol dependent (AD) and control smokers. Method AD (n=119) and control (n=55) ever smokers were compared on tobacco use history and nicotine dependence. Negative affect and craving to smoke were examined in a subsample of currently smoking AD (N=34) and control (N=19) participants during a six-hour period of tobacco abstinence using the Profile of Mood States (POMS) and the Questionnaire on Smoking Urges-Brief (QSU-B). Results Although AD smokers did not differ from controls on heaviness of smoking, they were more likely to meet lifetime criteria for nicotine dependence. AD smokers also reported more withdrawal symptoms and were more likely to endorse withdrawal-related depressed mood during past smoking reduction or abstinence periods. During short-term abstinence, AD smokers were more likely to report high craving to smoke for negative affect relief within the first 150 minutes of tobacco abstinence, but did not differ from controls on overall craving to smoke or withdrawal-related negative affect on the POMS. Conclusions Results support previous findings that AD smokers have a greater prevalence of nicotine dependence and more severe nicotine withdrawal, with a greater propensity toward withdrawal-related depressed mood. These results, along with our novel finding that greater craving to smoke in abstaining smokers with AD is specific to negative affect-related craving, suggest that negative reinforcement may be a particularly salient factor in the maintenance of tobacco use among individuals with AD. PMID:21106299

  18. The Mass Dependence of Star Formation Histories in Barred Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Carles, Christian; Martel, Hugo; Ellison, Sara L.; Kawata, Daisuke

    2016-08-01

    We performed a series of 29 gasdynamical simulations of disc galaxies, barred and unbarred, with various stellar masses, to study the impact of the bar on star formation history. Unbarred galaxies evolve very smoothly, with a star formation rate (SFR) that varies by at most a factor of three over a period of 2 Gyr. The evolution of barred galaxies is much more irregular, especially at high stellar masses. In these galaxies, the bar drives a substantial amount of gas toward the centre, resulting in a high SFR, and producing a starburst in the most massive galaxies. Most of the gas is converted into stars, and gas exhaustion leads to a rapid drop of star formation after the starburst. In massive barred galaxies (stellar mass M★ > 2 × 1010 M⊙) the large amount of gas funnelled toward the centre is completely consumed by the starburst, while in lower-mass barred galaxies it is only partially consumed. Gas concentration is thus higher in lower-mass barred galaxies than it is in higher-mass ones. Even though unbarred galaxies funnelled less gas toward their centre, the lower SFR allows this gas to accumulate. At late times, the star formation efficiency is higher in barred galaxies than unbarred ones, enabling these galaxies to maintain a higher SFR with a smaller gas supply. Several properties, such as the global SFR, central SFR, or central gas concentration, vary monotonically with time for unbarred galaxies, but not for barred galaxies. Therefore one must be careful when comparing barred and unbarred galaxies that share one observational property, since these galaxies might be at very different stages of their respective evolution.

  19. Neural Correlates of Impulsive Aggressive Behavior in Subjects With a History of Alcohol Dependence

    PubMed Central

    Kose, Samet; Steinberg, Joel L.; Moeller, F. Gerard; Gowin, Joshua L.; Zuniga, Edward; Kamdar, Zahra N.; Schmitz, Joy M.; Lane, Scott D.

    2015-01-01

    Alcohol-related aggression is a complex and problematic phenomenon with profound public health consequences. We examined neural correlates potentially moderating the relationship between human aggressive behavior and chronic alcohol use. Thirteen subjects meeting DSM–IV criteria for past alcohol-dependence in remission (AD) and 13 matched healthy controls (CONT) participated in an fMRI study adapted from a laboratory model of human aggressive behavior (Point Subtraction Aggression Paradigm, or PSAP). Blood oxygen level dependent (BOLD) activation was measured during bouts of operationally defined aggressive behavior, during postprovocation periods, and during monetary-reinforced behavior. Whole brain voxelwise random-effects analyses found group differences in brain regions relevant to chronic alcohol use and aggressive behavior (e.g., emotional and behavioral control). Behaviorally, AD subjects responded on both the aggressive response and monetary response options at significantly higher rates than CONT. Whole brain voxelwise random-effects analyses revealed significant group differences in response to provocation (monetary subtractions), with CONT subjects showing greater activation in frontal and prefrontal cortex, thalamus, and hippocampus. Collapsing data across all subjects, regression analyses of postprovocation brain activation on aggressive response rate revealed significant positive regression slopes in precentral gyrus and parietal cortex; and significant negative regression slopes in orbitofrontal cortex, prefrontal cortex, caudate, thalamus, and middle temporal gyrus. In these collapsed analyses, response to provocation and aggressive behavior were associated with activation in brain regions subserving inhibitory and emotional control, sensorimotor integration, and goal directed motor activity. PMID:25664566

  20. Solvent history dependence of gramicidin A conformations in hydrated lipid bilayers.

    PubMed Central

    LoGrasso, P V; Moll, F; Cross, T A

    1988-01-01

    Reconstituted lipid bilayers of dimyristoylphosphatidylcholine (DMPC) and gramicidin A' have been prepared by cosolubilizing gramicidin and DMPC in one of three organic solvent systems followed by vacuum drying and hydration. The conformational state of gramicidin as characterized by 23Na NMR, circular dichroism, and solid state 15N NMR is dependent upon the cosolubilizing solvent system. In particular, two conformational states are described; a state in which Na+ has minimal interactions with the polypeptide, referred to as a nonchannel state, and a state in which Na+ interacts very strongly with the polypeptide, referred to as the channel state. Both of these conformations are intimately associated with the hydrophobic core of the lipid bilayer. Furthermore, both of these states are stable in the bilayer at neutral pH and at a temperature above the bilayer phase transition temperature. These results with gramicidin suggest that the conformation of membrane proteins may be dictated by the conformation before membrane insertion and may be dependent upon the mechanism by which the insertion is accomplished. PMID:2462923

  1. Illusion of control in a Brownian game

    NASA Astrophysics Data System (ADS)

    Satinover, J. B.; Sornette, D.

    2007-12-01

    Both single-player Parrondo games (SPPG) and multi-player Parrondo games (MPPG) display the Parrondo effect (PE) wherein two or more individually fair (or losing) games yield a net winning outcome if alternated periodically or randomly. (There is a more formal, less restrictive definition of the PE.) We illustrate that, when subject to an elementary optimization rule, the PG displays degraded rather than enhanced returns. Optimization provides only the illusion of control, when low-entropy strategies (i.e., which use more information) under-perform random strategies (with maximal entropy). This illusion is unfortunately widespread in many human attempts to manage or predict complex systems. For the PG, the illusion is especially striking in that the optimization rule reverses an already paradoxical-seeming positive gain-the Parrondo effect proper-and turns it negative. While this phenomenon has been previously demonstrated using somewhat artificial conditions in the MPPG [L. Dinis, J.M.R. Parrondo, Europhys. Lett. 63 (2003) 319; J.M.R. Parrondo, L. Dinis, J. Buceta, K. Lindenberg, Advances in Condensed Matter and Statistical Mechanics, E. Korutcheva, R. Cuerno (Eds.), Nova Science Publishers, New York, 2003], we demonstrate it in the natural setting of a history-dependent SPPG.

  2. Marginal rigidity and history dependence in packings of attractive athermal emulsions

    NASA Astrophysics Data System (ADS)

    Bargteil, Dylan; Pontani, Lea-Laetitia; Brujic, Jasna

    2014-03-01

    The geometry and stress through particulate packings depends on the method of preparation and the interaction potential between the particles. Previously, we discovered that creaming frictionless, athermal emulsions with a short-range depletion attraction leads to an initial increase in the packing density above random close packing, followed by a monotonic decrease in density (Jorjadze et al, PNAS, 2011). This decrease is because the attractive force stabilizes loose voids, thus reducing the average coordination number, , of the packing. In order to understand the mechanism of packing creation, we investigate whether the final density is influenced by the polydispersity or the initial volume fraction of droplets, as it is in frictional packings. Finally, we compress the attractive packings by centrifugation to probe the scaling laws of pressure versus density and and compare them with those found in repulsive packings (Jorjadze et al, PRL, 2013).

  3. The history and future of targeting cyclin-dependent kinases in cancer therapy

    PubMed Central

    Asghar, Uzma; Witkiewicz, Agnieszka K.; Turner, Nicholas C.; Knudsen, Erik S.

    2015-01-01

    Cancer represents a pathological manifestation of uncontrolled cell division; therefore, it has long been anticipated that our understanding of the basic principles of cell cycle control would result in effective cancer therapies. In particular, cyclin-dependent kinases (CDKs) that promote transition through the cell cycle were expected to be key therapeutic targets because many tumorigenic events ultimately drive proliferation by impinging on CDK4 or CDK6 complexes in the G1 phase of the cell cycle. Moreover, perturbations in chromosomal stability and aspects of S phase and G2/M control mediated by CDK2 and CDK1 are pivotal tumorigenic events. Translating this knowledge into successful clinical development of CDK inhibitors has historically been challenging, and numerous CDK inhibitors have demonstrated disappointing results in clinical trials. Here, we review the biology of CDKs, the rationale for therapeutically targeting discrete kinase complexes and historical clinical results of CDK inhibitors. We also discuss how CDK inhibitors with high selectivity (particularly for both CDK4 and CDK6), in combination with patient stratification, have resulted in more substantial clinical activity. PMID:25633797

  4. Fundamental population-productivity relationships can be modified through density-dependent feedbacks of life-history evolution.

    PubMed

    Kuparinen, Anna; Stenseth, Nils Christian; Hutchings, Jeffrey A

    2014-12-01

    The evolution of life histories over contemporary time scales will almost certainly affect population demography. One important pathway for such eco-evolutionary interactions is the density-dependent regulation of population dynamics. Here, we investigate how fisheries-induced evolution (FIE) might alter density-dependent population-productivity relationships. To this end, we simulate the eco-evolutionary dynamics of an Atlantic cod (Gadus morhua) population under fishing, followed by a period of recovery in the absence of fishing. FIE is associated with increases in juvenile production, the ratio of juveniles to mature population biomass, and the ratio of the mature population biomass relative to the total population biomass. In contrast, net reproductive rate (R 0 ) and per capita population growth rate (r) decline concomitantly with evolution. Our findings suggest that FIE can substantially modify the fundamental population-productivity relationships that underlie density-dependent population regulation and that form the primary population-dynamical basis for fisheries stock-assessment projections. From a conservation and fisheries-rebuilding perspective, we find that FIE reduces R 0 and r, the two fundamental correlates of population recovery ability and inversely extinction probability. PMID:25558282

  5. Evidence for an age-dependent influence of environmental variations on a long-lived seabird's life-history traits.

    PubMed

    Pardo, Deborah; Barbraud, Christophe; Authier, Matthieu; Weimerskirch, Henri

    2013-01-01

    Theoretical and empirical studies have highlighted the effects of age on several life-history traits in wild populations. There is also increasing evidence for environmental effects on their demographic traits. However, quantifying how individuals differentially respond to environmental variations according to their age remains a challenge in ecology. In a population of Black-browed Albatrosses monitored during 43 years, we analyzed how life-history traits varied according to age, and whether individuals of different ages responded in different ways to environmental conditions. To do so, we: (1) examined how age affected seven life-history traits, (2) investigated differences in temporal variance of demographic traits between age classes, and (3) tested for age-dependent effects of climate and fisheries covariates on demographic traits. Overall, there was a tendency for traits to improve during the first years of life (5-10 years), to peak and remain stable at middle age (10-30 years), and decline at old ages. At young ages, survival and reproductive parameters increased, except offspring body condition at fledging, suggesting that younger parents had already acquired good foraging capacities. However, they suffered from inexperience in breeding as suggested by their higher breeding failures during incubation. There was evidence for reproductive and actuarial senescence. In particular, breeding success and offspring body condition declined abruptly, suggesting altered foraging capacities of old individuals. Middle-aged individuals had the lowest temporal variance of demographic traits. Although this is predicted by the theory of environmental canalization, it could also results from a higher susceptibility of young and old birds due to their respective inexperience and senescence. The highest temporal variances were found in old individuals. Survival was significantly influenced by sea surface temperatures in the foraging zone of this albatross population during

  6. How polyelectrolyte adsorption depends on history: A combined Fourier transform infrared spectroscopy in attenuated total reflection and surface forces study

    SciTech Connect

    Sukhishvili, S.A.; Dhinojwala, A.; Granick, S.

    1999-11-23

    The authors present a systematic study of how adsorption history affects the thickness, surface forces, and interfacial rheology of a model cationic polymer. The polymer was quaternized poly-4-vinylpyridine, QPVP (weight average degree of polymerization n{sub w} = 325 and 98% quaternized with ethyl bromide). The main comparisons concerned one-step adsorption from solution at a variable salt concentration up to 0.5 NaCl, versus two-step adsorption (initial adsorption from buffer solution without added salt, then NaCl added later). The aqueous solutions were buffered at pH = 9.2 such that the surfaces (mica in the case of surfaces forces (SFA) experiments, oxidized silicon in the case of in situ infrared (FTIR-ATR) experiments) in each case carried a large negative charge. The SFA and FTIR-ATR experiments gave consistent estimates of the amount of polymer adsorbed, confirming the expectation that adsorption should be driven by electrostatic attraction to the surface of large opposite charge. The adsorbed amount showed little dependence on path, validating the common assumption of equilibration in this respect. However the layer thickness measured by surface forces, the shear nanorheology response at a given surface force, and the dichroism of pendant side groups of the polymer all showed a pronounced dependence on the path to reach the adsorbed state. The authors interpret the measurements to suggest that two-step adsorption produces an inhomogeneous layer comprised of a dense layer of segments closest to the solid surface and a sparse outer layer. In particular, two-step adsorption produced thicker layers and a greater tendency to decouple shear forces from those that resist compression in the normal direction, thereby lessening the shear forces at a given level of normal force.

  7. Life-history differences in age-dependent expressions of multiple ornaments and behaviors in a lekking bird.

    PubMed

    Kervinen, Matti; Lebigre, Christophe; Alatalo, Rauno V; Siitari, Heli; Soulsbury, Carl D

    2015-01-01

    Age is a major factor explaining variation in life-history traits among individuals with typical patterns of increasing trait values early in life, maximum trait expression, and senescence. However, age-dependent variation in the expressions of sexually selected traits has received less attention, although such variation underpins differences in male competitive abilities and female preference, which are central to sexual selection. In contrast to previous studies focusing on single traits, we used repeated measures of seven sexually selected morphological and behavioral traits in male black grouse (Tetrao tetrix) to quantify the effects of age and life span on their expressions and quantified this variation in relation to male reproductive effort. Trait expression increased with age, but long-lived males had a slower increase and delayed maxima in trait values compared with short-lived males. There was evidence of terminal investment (increasing trait values during the last breeding season) in some traits and senescence in all traits. These trait dynamics were largely explained by the timing of male peak lekking effort. This study shows that fully understanding the variation in sexually selected traits and fitness benefits associated with sexual selection requires accounting for the complex interaction among individual age, life span, and the timing of individuals' investment in reproduction. PMID:25560550

  8. Spatially-resolved mapping of history-dependent coupled electrochemical and electronical behaviors of electroresistive NiO

    NASA Astrophysics Data System (ADS)

    Sugiyama, Issei; Kim, Yunseok; Jesse, Stephen; Strelcov, Evgheni; Kumar, Amit; Tselev, Alexander; Rahani, Ehasan Kabiri; Shenoy, Vivek B.; Yamamoto, Takahisa; Shibata, Naoya; Ikuhara, Yuichi; Kalinin, Sergei V.

    2014-10-01

    Bias-induced oxygen ion dynamics underpins a broad spectrum of electroresistive and memristive phenomena in oxide materials. Although widely studied by device-level and local voltage-current spectroscopies, the relationship between electroresistive phenomena, local electrochemical behaviors, and microstructures remains elusive. Here, the interplay between history-dependent electronic transport and electrochemical phenomena in a NiO single crystalline thin film with a number of well-defined defect types is explored on the nanometer scale using an atomic force microscopy-based technique. A variety of electrochemically-active regions were observed and spatially resolved relationship between the electronic and electrochemical phenomena was revealed. The regions with pronounced electroresistive activity were further correlated with defects identified by scanning transmission electron microscopy. Using fully coupled mechanical-electrochemical modeling, we illustrate that the spatial distribution of strain plays an important role in electrochemical and electroresistive phenomena. These studies illustrate an approach for simultaneous mapping of the electronic and ionic transport on a single defective structure level such as dislocations or interfaces, and pave the way for creating libraries of defect-specific electrochemical responses.

  9. Spatially-resolved mapping of history-dependent coupled electrochemical and electronical behaviors of electroresistive NiO

    SciTech Connect

    Sugiyama, Issei; Kim, Yunseok; Jesse, Stephen; Strelcov, Evgheni; Kumar, Amit; Tselev, Alexander; Rahani, Ehasan Kabiri; Shenoy, Vivek B.; Yamamoto, Takahisa; Shibata, Naoya; Ikuhara, Yuichi; Kalinin, Sergei V.

    2014-10-22

    Bias-induced oxygen ion dynamics underpins a broad spectrum of electroresistive and memristive phenomena in oxide materials. Although widely studied by device-level and local voltage-current spectroscopies, the relationship between electroresistive phenomena, local electrochemical behaviors, and microstructures remains elusive. Here, the interplay between history-dependent electronic transport and electrochemical phenomena in a NiO single crystalline thin film with a number of well-defined defect types is explored on the nanometer scale using an atomic force microscopy-based technique. A variety of electrochemically-active regions were observed and spatially resolved relationship between the electronic and electrochemical phenomena was revealed. The regions with pronounced electroresistive activity were further correlated with defects identified by scanning transmission electron microscopy. Using fully coupled mechanical-electrochemical modeling, we illustrate that the spatial distribution of strain plays an important role in electrochemical and electroresistive phenomena. In conclusion, these studies illustrate an approach for simultaneous mapping of the electronic and ionic transport on a single defective structure level such as dislocations or interfaces, and pave the way for creating libraries of defect-specific electrochemical responses.

  10. Spatially-resolved mapping of history-dependent coupled electrochemical and electronical behaviors of electroresistive NiO

    DOE PAGESBeta

    Sugiyama, Issei; Kim, Yunseok; Jesse, Stephen; Strelcov, Evgheni; Kumar, Amit; Tselev, Alexander; Rahani, Ehasan Kabiri; Shenoy, Vivek B.; Yamamoto, Takahisa; Shibata, Naoya; et al

    2014-10-22

    Bias-induced oxygen ion dynamics underpins a broad spectrum of electroresistive and memristive phenomena in oxide materials. Although widely studied by device-level and local voltage-current spectroscopies, the relationship between electroresistive phenomena, local electrochemical behaviors, and microstructures remains elusive. Here, the interplay between history-dependent electronic transport and electrochemical phenomena in a NiO single crystalline thin film with a number of well-defined defect types is explored on the nanometer scale using an atomic force microscopy-based technique. A variety of electrochemically-active regions were observed and spatially resolved relationship between the electronic and electrochemical phenomena was revealed. The regions with pronounced electroresistive activity were furthermore » correlated with defects identified by scanning transmission electron microscopy. Using fully coupled mechanical-electrochemical modeling, we illustrate that the spatial distribution of strain plays an important role in electrochemical and electroresistive phenomena. In conclusion, these studies illustrate an approach for simultaneous mapping of the electronic and ionic transport on a single defective structure level such as dislocations or interfaces, and pave the way for creating libraries of defect-specific electrochemical responses.« less

  11. Spatially-resolved mapping of history-dependent coupled electrochemical and electronical behaviors of electroresistive NiO

    PubMed Central

    Sugiyama, Issei; Kim, Yunseok; Jesse, Stephen; Strelcov, Evgheni; Kumar, Amit; Tselev, Alexander; Rahani, Ehasan Kabiri; Shenoy, Vivek B.; Yamamoto, Takahisa; Shibata, Naoya; Ikuhara, Yuichi; Kalinin, Sergei V.

    2014-01-01

    Bias-induced oxygen ion dynamics underpins a broad spectrum of electroresistive and memristive phenomena in oxide materials. Although widely studied by device-level and local voltage-current spectroscopies, the relationship between electroresistive phenomena, local electrochemical behaviors, and microstructures remains elusive. Here, the interplay between history-dependent electronic transport and electrochemical phenomena in a NiO single crystalline thin film with a number of well-defined defect types is explored on the nanometer scale using an atomic force microscopy-based technique. A variety of electrochemically-active regions were observed and spatially resolved relationship between the electronic and electrochemical phenomena was revealed. The regions with pronounced electroresistive activity were further correlated with defects identified by scanning transmission electron microscopy. Using fully coupled mechanical-electrochemical modeling, we illustrate that the spatial distribution of strain plays an important role in electrochemical and electroresistive phenomena. These studies illustrate an approach for simultaneous mapping of the electronic and ionic transport on a single defective structure level such as dislocations or interfaces, and pave the way for creating libraries of defect-specific electrochemical responses. PMID:25335689

  12. History dependence of the electromyogram: Implications for isometric steady-state EMG parameters following a lengthening or shortening contraction.

    PubMed

    Jones, Alexis A; Power, Geoffrey A; Herzog, Walter

    2016-04-01

    Residual force enhancement (RFE) and force depression (FD) refer to an increased or decreased force following an active lengthening or shortening contraction, respectively, relative to the isometric force produced at the same activation level and muscle length. Our intent was to determine if EMG characteristics differed in the RFE or FD states compared with a purely isometric reference contraction for maximal and submaximal voluntary activation of the adductor pollicis muscle. Quantifying these alterations to EMG in history-dependent states allows for more accurate modeling approaches for movement control in the future. For maximal voluntary contractions (MVC), RFE was 6-15% (P<0.001) and FD was 12-19% (P<0.001). The median frequency of the EMG was not different between RFE, FD and isometric reference contractions for the 100% and 40% MVC intensities (P>0.05). However, root mean square EMG (EMGRMS) amplitude for the submaximal contractions was higher in the FD and lower in the RFE state, respectively (P<0.05). For maximal contractions, EMGRMS was lower for the FD state but was the same for the RFE state compared to the isometric reference contractions (P>0.05). Neuromuscular efficiency (NME; force/EMG) was lower in the force depressed state and higher in the force enhanced state (P<0.05) compared to the isometric reference contractions. EMG spectral properties were not altered between the force-enhanced and depressed states relative to the isometric reference contractions, while EMG amplitude measures were. PMID:26891078

  13. Decreased Sensitivity to Long-Distance Dependencies in Children with a History of Specific Language Impairment: Electrophysiological Evidence

    PubMed Central

    Purdy, J. D.; Leonard, Laurence B.; Weber-Fox, Christine; Kaganovich, Natalya

    2015-01-01

    Purpose One possible source of tense and agreement limitations in children with SLI is a weakness in appreciating structural dependencies that occur in many sentences in the input. We tested this possibility in the present study. Method Children with a history of SLI (H-SLI; N = 12; M age 9;7) and typically developing same-age peers (TD; N = 12; M age 9;7) listened to and made grammaticality judgments about grammatical and ungrammatical sentences involving either a local agreement error (e.g., Every night they talks on the phone) or a long-distance finiteness error (e.g., He makes the quiet boy talks a little louder). Electrophysiological (ERP) and behavioral (accuracy) measures were obtained. Results Local agreement errors elicited the expected anterior negativity and P600 components in both groups of children. However, relative to the TD group, the P600 effect for the long-distance finiteness errors was delayed, reduced in amplitude, and shorter in duration for the H-SLI group. The children's grammaticality judgments were consistent with the ERP findings. Conclusions Children with H-SLI seem to be relatively insensitive to the finiteness constraints that matrix verbs place on subject-verb clauses that appear later in the sentence. PMID:24686983

  14. Theoretical life history responses of juvenile Oncorhynchus mykiss to changes in food availability using a dynamic state-dependent approach

    USGS Publications Warehouse

    Romine, Jason G.; Benjamin, Joseph R.; Perry, Russell W.; Casal, Lynne; Connolly, Patrick J.; Sauter, Sally S.

    2013-01-01

    Marine subsidies can play an important role in the growth, survival, and migratory behavior of rearing juvenile salmonids. Availability of high-energy, marine-derived food sources during critical decision windows may influence the timing of emigration or the decision to forego emigration completely and remain in the freshwater environment. Increasing growth and growth rate during these decision windows may result in an altered juvenile population structure, which will ultimately affect the adult population age-structure. We used a state dependent model to understand how the juvenile Oncorhynchus mykiss population structure may respond to increased availability of salmon eggs in their diet during critical decision windows. Our models predicted an increase in smolt production until coho salmon eggs comprised more than 50 percent of juvenile O. mykiss diet at the peak of the spawning run. At higher-than intermediate levels of egg consumption, smolt production decreased owing to increasing numbers of fish adopting a resident life-history strategy. Additionally, greater growth rates decreased the number of age-3 smolts and increased the number of age-2 smolts. Increased growth rates with higher egg consumption also decreased the age at which fish adopted the resident pathway. Our models suggest that the introduction of a high-energy food source during critical periods of the year could be sufficient to increase smolt production.

  15. Timescales of water transport in viscous aerosol: measurements on sub-micron particles and dependence on conditioning history.

    PubMed

    Lu, Jessica W; Rickards, Andrew M J; Walker, Jim S; Knox, Kerry J; Miles, Rachael E H; Reid, Jonathan P; Signorell, Ruth

    2014-06-01

    Evaporation studies of single aqueous sucrose aerosol particles as a function of relative humidity (RH) are presented for coarse and fine mode particles down into the submicron size range (600 nm < r < 3.0 μm). These sucrose particles serve as a proxy for biogenic secondary organic aerosols that have been shown to exist, under ambient conditions, in an ultraviscous glassy state, which can affect the kinetics of water mass transport within the bulk phase and hinder particle response to changes in the gas phase water content. A counter-propagating Bessel beams (CPBBs) optical trapping setup is employed to monitor the real-time change in the particle radius with RH decreasing from 75% to 5%. The slow-down of the size change upon each RH step and the deviation from the theoretical equilibrium hygroscopic growth curve indicate the onset of glassy behavior in the RH range of 10-40%. Size-dependent effects were not observed within the uncertainty of the measurements. The influence of the drying time below the glass transition RH on the timescale of subsequent water condensation and re-equilibration for sucrose particles is explored by optical tweezers measurements of micron-sized particles (3 μm < r < 6 μm). The timescale for water condensation and re-equilibration is shown to increase with increasing drying time, i.e. the time over which a viscous particle is dried below 5% RH. These studies demonstrate the importance of the history of the particle conditioning on subsequent water condensation and re-equilibration dynamics of ultraviscous and glassy aerosol particles. PMID:24316593

  16. Solution of the equation of heat conduction with time dependent sources: Programmed application to planetary thermal history

    NASA Technical Reports Server (NTRS)

    Conel, J. E.

    1975-01-01

    A computer program (Program SPHERE) solving the inhomogeneous equation of heat conduction with radiation boundary condition on a thermally homogeneous sphere is described. The source terms are taken to be exponential functions of the time. Thermal properties are independent of temperature. The solutions are appropriate to studying certain classes of planetary thermal history. Special application to the moon is discussed.

  17. Hung Out to Dry: Choice of Priority Ecoregions for Conserving Threatened Neotropical Anurans Depends on Life-History Traits

    PubMed Central

    Loyola, Rafael Dias; Becker, Carlos Guilherme; Kubota, Umberto; Haddad, Célio Fernando Baptista; Fonseca, Carlos Roberto; Lewinsohn, Thomas Michael

    2008-01-01

    Background In the Neotropics, nearly 35% of amphibian species are threatened by habitat loss, habitat fragmentation, and habitat split; anuran species with different developmental modes respond to habitat disturbance in different ways. This entails broad-scale strategies for conserving biodiversity and advocates for the identification of high conservation-value regions that are significant in a global or continental context and that could underpin more detailed conservation assessments towards such areas. Methodology/Principal Findings We identified key ecoregion sets for anuran conservation using an algorithm that favors complementarity (beta-diversity) among ecoregions. Using the WWF's Wildfinder database, which encompasses 700 threatened anuran species in 119 Neotropical ecoregions, we separated species into those with aquatic larvae (AL) or terrestrial development (TD), as this life-history trait affects their response to habitat disturbance. The conservation target of 100% of species representation was attained with a set of 66 ecoregions. Among these, 30 were classified as priority both for species with AL and TD, 26 were priority exclusively for species with AL, and 10 for species with TD only. Priority ecoregions for both developmental modes are concentrated in the Andes and in Mesoamerica. Ecoregions important for conserving species with AL are widely distributed across the Neotropics. When anuran life histories were ignored, species with AL were always underrepresented in priority sets. Conclusions/Significance The inclusion of anuran developmental modes in prioritization analyses resulted in more comprehensive coverage of priority ecoregions–especially those essential for species that require an aquatic habitat for their reproduction–when compared to usual analyses that do not consider this life-history trait. This is the first appraisal of the most important regions for conservation of threatened Neotropical anurans. It is also a first endeavor

  18. Insulin secretory defects in polycystic ovary syndrome. Relationship to insulin sensitivity and family history of non-insulin-dependent diabetes mellitus.

    PubMed Central

    Ehrmann, D A; Sturis, J; Byrne, M M; Karrison, T; Rosenfield, R L; Polonsky, K S

    1995-01-01

    The increased prevalence of non-insulin-dependent diabetes mellitus (NIDDM) among women with polycystic ovary syndrome (PCOS) has been ascribed to the insulin resistance characteristic of PCOS. This study was undertaken to determine the role of defects in insulin secretion as well as familial factors to the predisposition to NIDDM seen in PCOS. We studied three groups of women: PCOS with a family history of NIDDM (PCOS FHx POS; n = 11), PCOS without a family history of NIDDM (PCOS FHx NEG; n = 13), and women without PCOS who have a family history of NIDDM (NON-PCOS FHx POS; n = 8). Beta cell function was evaluated during a frequently sampled intravenous glucose tolerance test, by a low dose graded glucose infusion, and by the ability of the beta cell to be entrained by an oscillatory glucose infusion. PCOS FHx POS women were significantly less likely to demonstrate appropriate beta cell compensation for the degree of insulin resistance. The ability of the beta cell to entrain, as judged by the spectral power for insulin secretion rate, was significantly reduced in PCOS FHx POS subjects. In conclusion, a history of NIDDM in a first-degree relative appears to define a subset of PCOS subjects with a greater prevalence of insulin secretory defects. The risk of developing NIDDM imparted by insulin resistance in PCOS may be enhanced by these defects in insulin secretion. PMID:7615824

  19. Hypothalamus-pituitary-adrenal axis activity and the subsequent response to chronic stress differ depending upon life history stage.

    PubMed

    Lattin, Christine R; Bauer, Carolyn M; de Bruijn, Robert; Michael Romero, L

    2012-09-15

    The hypothalamus-pituitary-adrenal (HPA) axis is modulated seasonally in many species, and chronic stress can alter HPA functioning. However, it is not known how these two factors interact - are there particular life history stages when animals are more or less vulnerable to chronic stress? We captured wild house sparrows (Passer domesticus) in Massachusetts during six different life history stages: early and late winter, pre-laying, breeding, late breeding, and molt. At each time point, we tested HPA function by measuring baseline and stress-induced corticosterone (CORT), negative feedback in response to an injection of dexamethasone, and maximum adrenal response through an injection of adrenocorticotropic hormone. We then brought birds into captivity as a model for chronic stress, and repeated the four tests 5 days later. At capture, all HPA variables varied seasonally. Birds showed increased negative feedback during breeding and late winter compared to pre-laying. Furthermore, birds during the late breeding period had down-regulated their HPA axis, perhaps in preparation for molt. After 5 days of captivity, house sparrows lost ∼11% of initial body mass, although birds lost more weight during molt and early winter. Overall, captive sparrows showed elevated baseline CORT and increased negative feedback, although negative feedback did not show a significant increase during any individual life history stage. During most of the year, adrenal sensitivity was unaffected by captivity. However, during late breeding and molt, adrenal sensitivity increased during captivity. Taken together, these data provide further support that HPA function naturally varies throughout the year, with the interesting consequence that molting birds may potentially be more vulnerable to a chronic stressor such as captivity. PMID:22841762

  20. Determination of enthalpy-temperature curves of phase change materials with the temperature-history method: improvement to temperature dependent properties

    NASA Astrophysics Data System (ADS)

    Marín, José M.; Zalba, Belén; Cabeza, Luisa F.; Mehling, Harald

    2003-02-01

    The temperature-history method, proposed by Yinping et al, is a simple and economic way to determine the main thermophysical properties of materials used in thermal energy storage based on solid-liquid phase change. It is based on comparing the temperature history of a phase-change material sample and a sample of a well known material upon cooling down. In this paper we describe a further developed evaluation procedure to determine cp and h as temperature dependent values which was not the case in Yinping's method, based on the same experimental procedure. Given the suitability of these properties to calculate thermal energy storage using these materials, the method is proposed to present the results obtained in the form of enthalpy-temperature curves. A discussion about the errors produced by this method and an experimental improvement are proposed too.

  1. Formation and evolution of early-type galaxies - III. Dependence of the star formation history on the total mass and initial overdensity

    NASA Astrophysics Data System (ADS)

    Merlin, E.; Chiosi, C.; Piovan, L.; Grassi, T.; Buonomo, U.; Barbera, F. La

    2012-12-01

    We investigate the influence of the initial overdensities and masses of proto-galaxies on their subsequent evolution (the star formation history in particular) to understand whether these key parameters are sufficient to account for the varied properties of the galactic populations. By means of fully hydrodynamical N-body simulations performed with the code EVOL, we produce 12 self-similar models of early-type galaxies of different initial masses and overdensities, and follow their evolution from the early epochs (detachment from the linear regime and Hubble flow at z ≥ 20) down to the stage when mass assembly is complete, i.e. z ≤ 1 (in some cases the models are calculated up to z = 0). The simulations include radiative cooling, star formation, stellar energy feedback, re-ionizing photo-heating background and chemical enrichment of the interstellar medium; we do not consider the possible presence of active nuclei. We find a strong correlation between the initial properties of the proto-haloes and their subsequent star formation histories. Massive (Mtot ≃ 1013 M⊙) haloes experience a single, intense burst of star formation (with rates ≥103 M⊙ yr-1) at early epochs, consistently with observations, with less pronounced dependence on the initial overdensity; intermediate-mass (Mtot ≃ 1011 M⊙) haloes have histories that strongly depend on their initial overdensity, whereas low-mass haloes (Mtot ≃ 109 M⊙) always have erratic, bursting like star-forming histories, due to the 'galactic breathing' phenomenon. The model galaxies have morphological, structural and chemical properties resembling those of real galaxies, even though some disagreement still occurs, likely a consequence of some numerical choices. We conclude that total mass and initial overdensity drive the star formation histories of early-type galaxies. The model galaxies belong to the so-called quasi-monolithic (or early hierarchical) scenario in the sense that the aggregation of lumps of

  2. The alveolitis of pulmonary sarcoidosis. Evaluation of natural history and alveolitis-dependent changes in lung function

    SciTech Connect

    Keogh, B.A.; Hunninghake, G.W.; Line, B.R.; Crystal, R.G.

    1983-08-01

    Current concepts of the pathogenesis of pulmonary sarcoidosis suggest that a mononuclear cell alveolitis, comprised of activated T-lymphocytes and activated alveolar macrophages, precedes and modulates the formation of granuloma and fibrosis. To evaluate the natural history of this alveolitis and determine the relationship it has to subsequent changes in lung function, 19 untreated patients with pulmonary sarcoidosis without extrapulmonary manifestations were studied with bronchoalveolar lavage, /sup 67/Ga scanning, and pulmonary function tests to evaluate lung T-cells, lung alveolar macrophages, and lung function, respectively. In patients with sarcoidosis, low intensity alveolitis (lung T-cells less than or equal to 28% of all lung effector cells and/or /sup 67/Ga scan negative) was much more common (80% of all observations) than high intensity alveolitis (lung T-cells greater than 28% and /sup 67/Ga scan positive, 20% of all observations). Conventional clinical, roentgenographic, or physiologic studies could not predict the alveolitis status. Interestingly, of the 51 alveolitis evaluations in the 19 patients, there were 24 occurrences (47%) where the alveolitis was ''split,'' i.e., /sup 67/Ga scans positive and T-cells low (39%) or /sup 67/Ga negative and T-cells high (8%). Most untreated patients with sarcoidosis without extrapulmonary symptoms may have some inflammatory processes ongoing in their alveolar structures. Overall, whenever a high intensity alveolitis episode occurred, it was followed by deterioration over the next 6 months in at least one lung function parameter. A low intensity alveolitis episode was followed by functional deterioration only 8% of the time. The alveolitis parameters (lavage and /sup 67/Ga scanning) clearly predicted prognosis. These observations should prove useful in understanding the natural history of pulmonary sarcoidosis, in staging patients with this disease, and in making rational therapy decisions.

  3. Influence of the temperature dependence of thermal parameters of heat conduction models on the reconstruction of thermal history of igneous-intrusion-bearing basins

    NASA Astrophysics Data System (ADS)

    Wang, Dayong; Lu, Xiancai; Song, Yongchen; Shao, Rong; Qi, Tian

    2010-10-01

    Heat conduction models are important tools for reconstructing the thermal history of sedimentary basins affected by magmatic intrusions. Accurate thermal properties of the intrusion and its wall rocks are crucial for accurate predictions of thermal history. Although data on the thermal properties of rocks used in the models are not yet sufficient, we theoretically evaluated the influence of their temperature dependence on the reconstruction of the thermal history of wall rocks of a cooling intrusive sheet. In this study, due to their relatively adequate thermophysical data over wide temperature ranges, diabase, limestone, and Berea sandstone are assumed as the intrusion and the wall rocks in a heat conduction model. A linear interpolation algorithm is used to fit the temperature dependence of their thermal conductivity and specific heat based on experimental data. Simulations indicate that (a) the temperature dependence of these thermal properties can improve the estimation of the contact temperature ( Tc), (b) the deviation of Tc from a temperature-independent-coefficient heat conduction model can be as large as 102 °C for limestone and 61 °C for Berea sandstone, and (c) this is also the maximum deviation in the peak-temperature profile of wall rocks. However, its effect on the peak-temperature profile of wall rocks which is above 20 °C only occurs in a very narrow zone that is less than a half width of the intrusion away from the contact or a domain with the peak temperature above 500 °C. Furthermore, the temperature dependence can also significantly change the thermal-evolution history of wall rocks, lowering the cooling rate of magma intrusion and hence influencing the prediction of vitrinite reflectance ( Ro) based on the EASY%Ro model. Until a magma intrusion almost completely cools down, the maximum deviation in the predicted Ro profile of wall rocks from the temperature-independent-parameter heat conduction model can attain 0.47% for Berea sandstone at

  4. Effects of Place Identity, Place Dependence, and Experience-Use History on Perceptions of Recreation Impacts in a Natural Setting

    NASA Astrophysics Data System (ADS)

    White, Dave D.; Virden, Randy J.; van Riper, Carena J.

    2008-10-01

    It is generally accepted that recreation use in natural environments results in some degree of negative social and environmental impact. Environmental managers are tasked with mitigating the impact while providing beneficial recreation opportunities. Research on the factors that influence visitors’ perceptions of environmental and social conditions is necessary to inform sound environmental management of protected natural areas. This study examines the effect of prior experience with the setting and two dimensions of place attachment (i.e., place identity and place dependence) on visitors’ perceptions of three types of recreation impacts (i.e., depreciative behavior, environmental impacts, and recreation conflict). Principal components analysis, confirmatory factor analysis, and structural equation modeling were used to test the study hypotheses using data collected from 351 visitors through on-site questionnaires (response rate of 93 percent). The results show that prior experience exhibited a moderate and significant direct positive effect on place identity, place dependence, and visitors’ perceptions of recreation impacts. Contrary to study hypotheses and prior research, neither place dependence nor place identity exhibited a significant effect on the dependent variables. The results show that prior experience causes visitors to be more sensitive to depreciative behaviors, environmental impacts, and recreation conflict. These findings raise concerns over potential visitor displacement and deterioration of site conditions. Implications for resource managers are discussed, which include education, modifying visitor use patterns, and site design strategies.

  5. Committee Opinion No. 659 Summary: The Use of Vaginal Estrogen in Women With a History of Estrogen-Dependent Breast Cancer.

    PubMed

    2016-03-01

    Cancer treatment should address female-specific survivorship issues, including the hypoestrogenic- related adverse effects of cancer therapies or of natural menopause in survivors. Systemic and vaginal estrogen are widely used for symptomatic relief of vasomotor symptoms, sexual dysfunction, and lower urinary tract infections in the general population. However, given that some types of cancer are hormone sensitive, there are safety concerns about the use of local hormone therapy in women who currently have breast cancer or have a history of breast cancer. Nonhormonal approaches are the first-line choices for managing urogenital symptoms or atrophy-related urinary symptoms experienced by women during or after treatment for breast cancer. Among women with a history of estrogen-dependent breast cancer who are experiencing urogenital symptoms, vaginal estrogen should be reserved for those patients who are unresponsive to nonhormonal remedies. The decision to use vaginal estrogen may be made in coordination with a woman's oncologist. Additionally, it should be preceded by an informed decision-making and consent process in which the woman has the information and resources to consider the benefits and potential risks of low-dose vaginal estrogen. Data do not show an increased risk of cancer recurrence among women currently undergoing treatment for breast cancer or those with a personal history of breast cancer who use vaginal estrogen to relieve urogenital symptoms. PMID:26901332

  6. Satellite alignment. I. Distribution of substructures and their dependence on assembly history from n-body simulations

    SciTech Connect

    Wang, Yang Ocean; Lin, W. P.; Yu, Yu; Kang, X.; Dutton, Aaron; Macciò, Andrea V. E-mail: linwp@shao.ac.cn

    2014-05-01

    Observations have shown that the spatial distribution of satellite galaxies is not random, but aligned with the major axes of central galaxies. This alignment is dependent on galaxy properties, such that red satellites are more strongly aligned than blue satellites. Theoretical work conducted to interpret this phenomenon has found that it is due to the non-spherical nature of dark matter halos. However, most studies overpredict the alignment signal under the assumption that the central galaxy shape follows the shape of the host halo. It is also not clear whether the color dependence of alignment is due to an assembly bias or an evolution effect. In this paper we study these problems using a cosmological N-body simulation. Subhalos are used to trace the positions of satellite galaxies. It is found that the shapes of dark matter halos are mis-aligned at different radii. If the central galaxy shares the same shape as the inner host halo, then the alignment effect is weaker and agrees with observational data. However, it predicts almost no dependence of alignment on the color of satellite galaxies, though the late accreted subhalos show stronger alignment with the outer layer of the host halo than their early accreted counterparts. We find that this is due to the limitation of pure N-body simulations where satellite galaxies without associated subhalos ('orphan galaxies') are not resolved. These orphan (mostly red) satellites often reside in the inner region of host halos and should follow the shape of the host halo in the inner region.

  7. Satellite Alignment. I. Distribution of Substructures and their Dependence on Assembly History from N-body Simulations

    NASA Astrophysics Data System (ADS)

    Wang, Y. O.; Lin, W. P.; Kang, X.; Dutton, Aaron; Yu, Yu; Macciò, Andrea V.

    2014-05-01

    Observations have shown that the spatial distribution of satellite galaxies is not random, but aligned with the major axes of central galaxies. This alignment is dependent on galaxy properties, such that red satellites are more strongly aligned than blue satellites. Theoretical work conducted to interpret this phenomenon has found that it is due to the non-spherical nature of dark matter halos. However, most studies overpredict the alignment signal under the assumption that the central galaxy shape follows the shape of the host halo. It is also not clear whether the color dependence of alignment is due to an assembly bias or an evolution effect. In this paper we study these problems using a cosmological N-body simulation. Subhalos are used to trace the positions of satellite galaxies. It is found that the shapes of dark matter halos are mis-aligned at different radii. If the central galaxy shares the same shape as the inner host halo, then the alignment effect is weaker and agrees with observational data. However, it predicts almost no dependence of alignment on the color of satellite galaxies, though the late accreted subhalos show stronger alignment with the outer layer of the host halo than their early accreted counterparts. We find that this is due to the limitation of pure N-body simulations where satellite galaxies without associated subhalos ("orphan galaxies") are not resolved. These orphan (mostly red) satellites often reside in the inner region of host halos and should follow the shape of the host halo in the inner region.

  8. Landscape history and land-use dependent soil erosion in central Bosnia from the Bronze Age to Medieval Times

    NASA Astrophysics Data System (ADS)

    Wolters, Steffen; Enters, Dirk; Bittmann, Felix

    2010-05-01

    The inland areas of the northwestern Balkan peninsula and in particular of Bosnia and Herzegovina are poor in natural archives suitable for the reconstruction of past environmental changes and vegetation history. Consequently, palaeoenvironmental analyses are scarce with only three palynological studies available dating back to 1973, 1956 and 1934. Central Bosnia, however, is rich in archaeological heritage, featuring numerous prehistoric settlement sites along the river Bosna starting in the early Neolithic. This generates the need for palaeoenvironmental reconstructions to support and complement recent archaeological research in this area. Here we present results from a 450 cm gyttja-peat sequence from Seoce Jezero, a small mire located at 600 m NN on a plateau above a tributary of the river Bosna 30 km northwest of Sarajevo (central Bosnia). Fourteen AMS C-14 dates provide a robust time-depth-relationship which covers natural and anthropogenic environmental changes at Seoce Jezero from the Bronze Age to early Medieval Times. Pollen, macrofossil and geochemical analyses of 167 samples produce a high resolution record of land-use and vegetation change up to a half-decadal time scale. The palaeoenvironmental record starts ca. 1800 BC (3750 cal. BP) and reveals an initially relatively undisturbed landscape dominated by Fagus- and Quercus-Carpinus woodland. Anthropogenic influence is clearly visible from 1400 BC (3350 cal. BP) onwards and comprises woodland clearances, pasturing and crop cultivation. Pollen analyses confirm several consecutive phases of different land-use character and intensity. Phases of high land-use pressure culminated at the transition Bronze Age/Iron Age (1100 BC), the late Iron Age (400 BC), late Roman times (AD 300) and from AD 700 onwards. In between, stages of forest regeneration could be detected, most pronounced in the period between 70 BC and AD 150 (2020-1800 cal. BP), when anthropogenic influence virtually ceased. Whereas land use in

  9. Developmental Momentum toward Substance Dependence: Natural Histories and Pliability of Risk Factors in Youth Experiencing Chronic Stress

    PubMed Central

    Ridenour, Ty A.; Meyer-Chilenski, Sarah; Reid, Erin E.

    2012-01-01

    BACKGROUND Mitigation of substance use (SU) disorder (SUD) risk factors is a common goal of prevention. Research has clarified much about risk factors including their prediction of SU/SUD, associations with other etiological variables and mediation of SU outcomes. Greater understanding of the emergence of risk factors themselves may improve prevention. For example, in lieu of experimental data, the level of resistance to change of a risk factor (its pliability) could inform “dosage” of intervention needed to reduce the risk. METHODS Two attributes of 22 previously-documented predictors of SU/SUD were quantified: natural history (average age-related trend) and pliability (quantified using correlations between intercepts and growth parameters of hierarchical linear modeling trajectories). The longitudinal sample of 1,147 8- through 16-year-olds were recruited from a northeastern summer camp for youth experiencing chronic stress due to one or more stressors (X̄ = 2.2 stressors, SD=1.41) which typically last at least one year. Half were male, 69.3% were European-American, 8.5% were African-American, and the remaining were small proportions each of other or mixed races/ethnicities. RESULTS Average trajectories of 21 predictors correspond to increasing SUD risk with age. Predictor pliability varied greatly, ranging from extremely high for School Commitment to extremely low for Peer Pressure Susceptibility. CONCLUSIONS Results suggest different intervention strategies may be needed to manage risk factors over the long-term. To illustrate, maintaining a high school commitment appears to require boosters whereas reducing peer pressure susceptibility appears to require high initial “dosage” with less need for boosters. PMID:22257754

  10. Pollutant Dehalogenation Capability May Depend on the Trophic Evolutionary History of the Organism: PBDEs in Freshwater Food Webs

    PubMed Central

    Bartrons, Mireia; Grimalt, Joan O.; de Mendoza, Guillermo; Catalan, Jordi

    2012-01-01

    Organohalogen compounds are some of the most notorious persistent pollutants disturbing the Earth biosphere. Although human-made, these chemicals are not completely alien to living systems. A large number of natural organohalogens, part of the secondary metabolism, are involved in chemical trophic interactions. Surprisingly, the relationship between organisms’ trophic position and synthetic organohalogen biotransformation capability has not been investigated. We studied the case for polybromodiphenyl ethers (PBDE), a group of flame-retardants of widespread use in the recent years, in aquatic food webs from remote mountain lakes. These relatively simple ecosystems only receive pollution by atmospheric transport. A large predominance of the PBDE congener currently in use in Europe, BDE-209, largely dominated the PBDE composition of the basal resources of the food web. In contrast, primary consumers (herbivores and detritivores) showed a low proportion of BDE-209, and dominance of several less brominated congeners (e.g. BDE-100, BDE47). Secondary consumers (predators) showed large biomagnification of BDE-209 compare to other congeners. Finally, top predator fish characterized by low total PBDE concentrations. Examination of the bromine stable isotopic composition indicates that primary consumers showed higher PBDE biotransformation capability than secondary consumers. We suggest that the evolutionary response of primary consumers to feeding deterrents would have pre-adapted them for PBDE biotransformation. The observed few exceptions, some insect taxa, can be interpreted in the light of the trophic history of the evolutionary lineage of the organisms. Bromine isotopic composition in fish indicates that low PBDE values are due to not only biotransformation but also to some other process likely related to transport. Our finding illustrates that organohalogen compounds may strongly disturb ecosystems even at low concentrations, since the species lacking or having

  11. Circadian timing in central and peripheral tissues in a migratory songbird: dependence on annual life-history states.

    PubMed

    Singh, Devraj; Trivedi, Amit Kumar; Rani, Sangeeta; Panda, Satchidananda; Kumar, Vinod

    2015-10-01

    Predictable seasonal change in photoperiod triggers a sequential change in the daily activity-rest pattern, adaptive for migration in several bird species. The night-migratory black-headed bunting (Emberiza melanocephala) is day active under short photoperiods (8 h light:16 h dark, short day sensitive). Under long photoperiods (16 h light:8 h dark), the buntings are initially day active (long day premigratory) but subsequently become intensely night active (long day migratory) and after few weeks again return to a day active pattern (long day refractory). However, it is unclear how the daily expression of circadian genes changes during photoperiod-induced seasonal life-history states (LHSs). We measured period 2 (Per2), cryptochrome 1 (Cry1), brain and muscle arnt-like protein 1 (Bmal1), and circadian locomotor output cycles kaput (Clock) mRNA expressions in various neural and peripheral tissues of buntings in different LHSs and discovered differences of ∼2 to 6 h in the phase and 2- to 4-fold in amplitude of circadian oscillations of Per2, Cry1, and Bmal1 between photoperiod-induced LHSs. Phase relationship in mRNA oscillations was altered between oscillator components in the circadian pacemaker system (retina, pineal, hypothalamus) as well as in the peripheral (liver, muscle) tissues. These results show for the first time altered waveforms of clock gene expressions in all tissues in parallel with behavioral shifts and suggest the involvement of circadian system in photoperiod induction of seasonal LHSs in a migratory species. PMID:26103987

  12. Fronto-temporal alterations and affect regulation in methamphetamine dependence with and without a history of psychosis.

    PubMed

    Uhlmann, Anne; Fouche, Jean-Paul; Koen, Nastassja; Meintjes, Ernesta M; Wilson, Don; Stein, Dan J

    2016-02-28

    Methamphetamine (MA) has been shown to have neurotoxic effects associated with brain structure changes and schizophrenia-like psychotic symptoms. Although these abnormalities may in turn be related to cognitive impairment and increased aggression, their association with affect dysregulation is less well studied. We investigated cortical thickness and subcortical volumes in 21 participants with MA dependence, 19 patients with MA-associated psychosis (MAP), and 19 healthy controls. Participants' affect regulation abilities were assessed through self-report scales on emotion reactivity (ERS) and difficulties in emotion regulation (DERS) and correlated with differences in cortical thickness. MAP patients showed thinner cortices in the fusiform and inferior temporal gyrus (ITG), orbitofrontal (OFC) and inferior frontal gyrus (IFG), and insula, compared to the MA group. MAP also showed significantly lower hippocampal volumes relative to MA and CTRL. Both clinical groups showed impairment in affect regulation, but only in MAP was this dysfunction associated with thinner cortices in ITG, OFC and IFG. Our findings suggest significant differences in cortical thickness in MA dependence with and without psychosis. Lower fronto-temporal cortical thickness and smaller hippocampal volumes in MAP are consistent with neuroimaging findings in other psychotic disorders, supporting the notion of MAP being a useful model of psychosis. PMID:26792587

  13. THE MASS-DEPENDENT CLUSTERING HISTORY OF K-SELECTED GALAXIES AT z < 4 IN THE SXDS/UDS FIELD

    SciTech Connect

    Furusawa, Junko; Sekiguchi, Kazuhiro; Takata, Tadafumi; Furusawa, Hisanori; Shimasaku, Kazuhiro; Simpson, Chris; Akiyama, Masayuki

    2011-02-01

    We investigate mass-dependent galaxy evolution based on a large sample of (more than 50,000) K-band selected galaxies in a multi-wavelength catalog of the Subaru/XMM-Newton Deep Survey and the UKIRT Infrared Deep Sky Survey/Ultra Deep Survey. We employ optical to near-infrared photometry to determine photometric redshifts of these galaxies. Then, we estimate the stellar mass of our sample galaxies using a standard fitting procedure as we used for estimation of the photometric redshift. From the sample galaxies, we obtain the stellar mass function of galaxies and the cosmic stellar mass density up to z {approx} 4. Our results are consistent with previous studies and we find a considerable number of low-mass galaxies (M{sub *} {approx} 10{sup 10.5}) at the redshift range 3 < z < 4. By combining stellar masses and spatial distributions of galaxies derived from a large number of galaxies in the contiguous wide and deep field, we examine properties of the mass-dependent clustering of galaxies. The correlation functions of our sample galaxies show clear evolution and they connect to that in the local universe consistently. Also, we find that the massive galaxies show strong clustering throughout our studied redshift range. The correlation length of massive galaxies rapidly decreases from z = 4 to 2. The mass of dark halos hosting the intermediate-mass value galaxies changes from high (10{sup 14} M{sub sun}) to low (10{sup 13} M{sub sun}) with decreasing redshift at around z {approx} 2. We also find some high-mass density regions of massive galaxies at 1.4 {<=} z < 2.5 in our sample. These concentrations of massive galaxies may be candidate progenitors of the present-day clusters of galaxies. At this redshift range, massive star-forming galaxies are the dominant population making up the structures and the passively evolving galaxies show stronger clustering and they may have formed earlier than those star-forming galaxies.

  14. History-dependent ion transport through conical nanopipettes and the implications in energy conversion dynamics at nanoscale interfaces

    DOE PAGESBeta

    Li, Yan; Wang, Dengchao; Kvetny, Maksim M.; Brown, Warren; Liu, Juan; Wang, Gangli

    2014-08-20

    The dynamics of ion transport at nanostructured substrate–solution interfaces play vital roles in high-density energy conversion, stochastic chemical sensing and biosensing, membrane separation, nanofluidics and fundamental nanoelectrochemistry. Advancements in these applications require a fundamental understanding of ion transport at nanoscale interfaces. The understanding of the dynamic or transient transport, and the key physical process involved, is limited, which contrasts sharply with widely studied steady-state ion transport features at atomic and nanometer scale interfaces. Here we report striking time-dependent ion transport characteristics at nanoscale interfaces in current–potential (I–V) measurements and theoretical analyses. First, a unique non-zero I–V cross-point and pinched I–Vmore » curves are established as signatures to characterize the dynamics of ion transport through individual conical nanopipettes. Moreoever, ion transport against a concentration gradient is regulated by applied and surface electrical fields. The concept of ion pumping or separation is demonstrated via the selective ion transport against concentration gradients through individual nanopipettes. Third, this dynamic ion transport process under a predefined salinity gradient is discussed in the context of nanoscale energy conversion in supercapacitor type charging–discharging, as well as chemical and electrical energy conversion. Our analysis of the emerging current–potential features establishes the urgently needed physical foundation for energy conversion employing ordered nanostructures. The elucidated mechanism and established methodology can be generalized into broadly-defined nanoporous materials and devices for improved energy, separation and sensing applications.« less

  15. History-dependent ion transport through conical nanopipettes and the implications in energy conversion dynamics at nanoscale interfaces

    SciTech Connect

    Li, Yan; Wang, Dengchao; Kvetny, Maksim M.; Brown, Warren; Liu, Juan; Wang, Gangli

    2014-08-20

    The dynamics of ion transport at nanostructured substrate–solution interfaces play vital roles in high-density energy conversion, stochastic chemical sensing and biosensing, membrane separation, nanofluidics and fundamental nanoelectrochemistry. Advancements in these applications require a fundamental understanding of ion transport at nanoscale interfaces. The understanding of the dynamic or transient transport, and the key physical process involved, is limited, which contrasts sharply with widely studied steady-state ion transport features at atomic and nanometer scale interfaces. Here we report striking time-dependent ion transport characteristics at nanoscale interfaces in current–potential (I–V) measurements and theoretical analyses. First, a unique non-zero I–V cross-point and pinched I–V curves are established as signatures to characterize the dynamics of ion transport through individual conical nanopipettes. Moreoever, ion transport against a concentration gradient is regulated by applied and surface electrical fields. The concept of ion pumping or separation is demonstrated via the selective ion transport against concentration gradients through individual nanopipettes. Third, this dynamic ion transport process under a predefined salinity gradient is discussed in the context of nanoscale energy conversion in supercapacitor type charging–discharging, as well as chemical and electrical energy conversion. Our analysis of the emerging current–potential features establishes the urgently needed physical foundation for energy conversion employing ordered nanostructures. The elucidated mechanism and established methodology can be generalized into broadly-defined nanoporous materials and devices for improved energy, separation and sensing applications.

  16. The dependence of galaxy star formation histories on environment at 0.6 < z < 0.9

    NASA Astrophysics Data System (ADS)

    Patel, Shannon

    We used a low-dispersion prism (LDP) in IMACS on the 6.5 m Baade (Magellan I) telescope to obtain low resolution spectroscopy of galaxies with 18 < zAB < 23.3 mag over a ˜0.2 deg2 field. In contrast to spectra obtained through a traditional grating, the resolution of LDP spectra was a strong function of wavelength, with the spectral resolving power of the LDP varying from R ˜ 66 at 5000 A to R ˜ 15 at 8500 A. Stellar population synthesis models were fit to the relative flux calibrated LDP spectra and Subaru Suprime-Cam V Riz photometry in order to measure redshifts. We measured ˜10,000 redshifts to a precision of ˜1% in (1 + z). Given the emerging consensus regarding the key role of stellar mass in shaping the star formation histories (SFHs) of galaxies, we aimed to study stellar mass limited samples. Our z-band spectroscopic selection was critical in assembling samples to low mass limits at 0.6 < z < 0.9. Our final sample consisted of ˜1100 galaxies at 0.6 < z < 0.9 above a mass limit of M > 1.8 x 1010 M⊙ (log M/ M⊙ > 10.25). This mass limit roughly corresponds to 0.2M ⋆, thus reaching well below the knee of the Schechter mass function and also a factor of two below the threshold mass above which galaxy properties appear to be primarily determined by stellar mass. The rest-frame color of a galaxy serves as trace for the age of its stellar populations. We investigated the rest-frame u -- g color of galaxies as a function of local density in a redshift slice (0.80 < z < 0.87) containing the cluster RX J0152.7-1357 as well as several other groups. We find that the fraction of red galaxies increases at higher densities, reaching ˜90--100% in the cores of moderate mass groups, the same value as found in the center of RX J0152.7-1357, and suggesting the presence of older stellar populations in these high density environments. Because dust obscuration can make younger star forming galaxies (SFGs) appear red, we investigated the obscured star formation rates

  17. Match or mismatch: the influence of phenology on size-dependent life history and divergence in population structure

    USGS Publications Warehouse

    Borcherding, Jost; Beeck, Peter; DeAngelis, Donald L.; Scharf, Werner R.

    2010-01-01

    age cohort of the predator. 6. The results demonstrate that the switch between competitive interactions and a predator-prey relationship depended on phenology. This resulted in pronounced size differences in the YOY age cohort, which had far-reaching consequences for the entire predator population.

  18. Attention problems among children with a positive family history of alcohol abuse or dependence and controls. Prevalence and course for the period from preteen to early teen years.

    PubMed

    Barnow, Sven; Schuckit, Marc; Smith, Tom; Spitzer, Carsten; Freyberger, Harald-J

    2007-01-01

    This longitudinal study investigated the scope and course of attention problems over a period of time from preteen (ages 7-12 years) to early teen years (ages 13-17 years). We compared symptoms in subjects with and without a family history (FH) of alcohol abuse or dependence from among families without evidence of antisocial personality disorder. Evaluations of attention problems for the offspring were based on the Child Behavior Checklist and a validated semistructured interview carried out with the mother. The findings indicate no higher risk for attention problems and attention-deficit hyperactivity disorder (ADHD)-like symptoms in the children of families with an alcohol use disorder. Regarding the course of problems, the ADHD symptom count tended to decrease over time, especially for children without a FH of alcohol abuse or dependence. Further research will be needed to determine whether results can be replicated with families from different social strata and including subjects with the antisocial personality disorder. PMID:17172772

  19. History dependent crystallization of Zr{sub 41}Ti{sub 14}Cu{sub 12}Ni{sub 10}Be{sub 23} melts

    SciTech Connect

    Schroers, Jan; Johnson, William L.

    2000-07-01

    The crystallization of Zr{sub 41}Ti{sub 14}Cu{sub 12}Ni{sub 10}Be{sub 23} (Vit 1) melts during constant heating is investigated. (Vit 1) melts are cooled with different rates into the amorphous state and the crystallization temperature upon subsequent heating is studied. In addition, Vit 1 melts are cooled using a constant rate to different temperatures and subsequently heated from this temperature with a constant rate. We investigate the influence of the temperature to which the melt was cooled on the crystallization temperature measured upon heating. In both cases the onset temperature of crystallization shows strong history dependence. This can be explained by an accumulating process during cooling and heating. An attempt is made to consider this process in a simple model by steady state nucleation and subsequent growth of the nuclei which results in different crystallization kinetics during cooling or heating. Calculations show qualitative agreement with the experimental results. However, calculated and experimental results differ quantitatively. This difference can be explained by a decomposition process leading to a nonsteady nucleation rate which continuously increases with decreasing temperature. (c) 2000 American Institute of Physics.

  20. Bayesian deterministic decision making: a normative account of the operant matching law and heavy-tailed reward history dependency of choices

    PubMed Central

    Saito, Hiroshi; Katahira, Kentaro; Okanoya, Kazuo; Okada, Masato

    2014-01-01

    The decision making behaviors of humans and animals adapt and then satisfy an “operant matching law” in certain type of tasks. This was first pointed out by Herrnstein in his foraging experiments on pigeons. The matching law has been one landmark for elucidating the underlying processes of decision making and its learning in the brain. An interesting question is whether decisions are made deterministically or probabilistically. Conventional learning models of the matching law are based on the latter idea; they assume that subjects learn choice probabilities of respective alternatives and decide stochastically with the probabilities. However, it is unknown whether the matching law can be accounted for by a deterministic strategy or not. To answer this question, we propose several deterministic Bayesian decision making models that have certain incorrect beliefs about an environment. We claim that a simple model produces behavior satisfying the matching law in static settings of a foraging task but not in dynamic settings. We found that the model that has a belief that the environment is volatile works well in the dynamic foraging task and exhibits undermatching, which is a slight deviation from the matching law observed in many experiments. This model also demonstrates the double-exponential reward history dependency of a choice and a heavier-tailed run-length distribution, as has recently been reported in experiments on monkeys. PMID:24624077

  1. Family History

    MedlinePlus

    ... CDC Cancel Submit Search The CDC Family Health History Note: Javascript is disabled or is not supported ... visit this page: About CDC.gov . Family Health History The Basics Family Health History & Chronic Disease Planning ...

  2. INTERACTIONS BETWEEN THYROID AND CORTICOSTEROID SYSTEMS DURING THE EARLY LIFE HISTORY OF AN ESTUARINE DEPENDENT FISH: A POSSIBLE TARGET FOR ENDOCRINE DISRUPTION BY ATRAZINE

    EPA Science Inventory

    This research will determine whether interactions between the thyroid and corticosteroid systems are consistent throughout the early life history of marine fish, or whether such interactions vary during development. This study will indicate whether endocrine related gene expr...

  3. Tracing the Mass-Dependent Star Formation History of Late-Type Galaxies using X-ray Emission: Results from the CHANDRA Deep Fields

    NASA Technical Reports Server (NTRS)

    Lehmer, B.D; Brandt, W.N.; Schneider, D.P.; Steffen, A.T.; Alexander, D.M.; Bell, E.F.; Hornschemeier, A.E.; McIntosh, D.H.; Bauer, F.E.; Gilli, R.; Mainieri, V.; Silverman, J.D.; Tozzi, P.; Wolf, C.

    2008-01-01

    We report on the X-ray evolution over the last approx.9 Gyr of cosmic history (i.e., since z = 1.4) of late-type galaxy populations in the Chandra Deep Field-North and Extended Chandra Deep Field-South (CDF-N and E-CDF-S. respectively; jointly CDFs) survey fields. Our late-type galaxy sample consists of 2568 galaxies. which were identified using rest-frame optical colors and HST morphologies. We utilized X-ray stacking analyses to investigate the X-ray emission from these galaxies, emphasizing the contributions from normal galaxies that are not dominated by active galactic nuclei (AGNs). Over this redshift range, we find significant increases (factors of approx. 5-10) in the X-ray-to-optical mean luminosity ratio (L(sub x)/L(sub B)) and the X-ray-to-stellar-mass mean ratio (L(sub x)/M(sub *)) for galaxy populations selected by L(sub B) and M(sub *), respectively. When analyzing galaxy samples selected via SFR, we find that the mean X-ray-to-SFR ratio (L(sub x)/SFR) is consistent with being constant over the entire redshift range for galaxies with SFR = 1-100 Solar Mass/yr, thus demonstrating that X-ray emission can be used as a robust indicator of star-formation activity out to z approx. 1.4. We find that the star-formation activity (as traced by X-ray luminosity) per unit stellar mass in a given redshift bin increases with decreasing stellar mass over the redshift range z = 0.2-1, which is consistent with previous studies of how star-formation activity depends on stellar mass. Finally, we extend our X-ray analyses to Lyman break galaxies at z approx. 3 and estimate that L(sub x)/L(sub B) at z approx. 3 is similar to its value at z = 1.4.

  4. Doing History.

    ERIC Educational Resources Information Center

    Beery, Robert W.

    When elementary students examine primary sources and local historical sites to gain firsthand information about life in the past, history becomes more relevant, exciting, and enjoyable. To help students understand that history is not just what is in a textbook, this student resource book focuses on making them aware that history exists all around…

  5. Temperature- and Relative Humidity-Dependent Life History Traits of Phenacoccus solenopsis (Hemiptera: Pseudococcidae) on Hibiscus rosa-sinensis (Malvales: Malvaceae).

    PubMed

    Chen, H S; Yang, L; Huang, L F; Wang, W L; Hu, Y; Jiang, J J; Zhou, Z S

    2015-08-01

    Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), a worldwide distributive invasive pest, originated from the United States, and it was first reported in Guangdong province, China, in 2008. The effects of temperature and relative humidity (RH) on the life history traits of P. solenopsis on Hibiscus rosa-sinensis L. (Malvales: Malvaceae) were studied at seven constant temperatures (15, 20, 25, 27.5, 30, 32.5, and 35°C) and three RHs (45, 60, and 75%). The results showed that temperature, RH, and their interactions significantly influenced the life history traits of P. solenopsis. First instar was the most sensitive stage to extreme temperatures with very low survival rates at 15 and 35°C. At 25-32.5°C and the three RHs, the developmental periods of entire immature stage were shorter with values between 12.5-18.6 d. The minimum threshold temperature and the effective accumulative temperature for the pest to complete one generation were 13.2°C and 393.7 degree-days, respectively. The percentage and longevity of female adults significantly differed among different treatments. It failed to complete development at 15 or 35°C and the three RHs. Female fecundity reached the maximum value at 27.5°C and 45% RH. The intrinsic rate for increase (r), the net reproductive rate (R0), and the finite rate of increase (λ) reached the maximum values at 27.5°C and 45% RH (0.22 d(-1), 244.6 hatched eggs, and 1.25 d(-1), respectively). Therefore, we conclude that 27.5°C and 45% RH are the optimum conditions for the population development of the pest. PMID:26314069

  6. Support for a history-dependent predictive model of dACC activity in producing the bivalency effect: an event-related potential study.

    PubMed

    Grundy, John G; Shedden, Judith M

    2014-05-01

    In the present study, we examine electrophysiological correlates of factors influencing an adjustment in cognitive control known as the bivalency effect. During task-switching, the occasional presence of bivalent stimuli in a block of univalent trials is enough to elicit a response slowing on all subsequent univalent trials. Bivalent stimuli can be congruent or incongruent with respect to the response afforded by the irrelevant stimulus feature. Here we show that the incongruent bivalency effect, the congruent bivalency effect, and an effect of a simple violation of expectancy are captured at a frontal ERP component (between 300 and 550ms) associated with ACC activity, and that the unexpectedness effect is distinguished from both congruent and incongruent bivalency effects at an earlier component (100-120ms) associated with the temporal parietal junction. We suggest that the frontal component reflects the dACC's role in predicting future cognitive load based on recent history. In contrast, the posterior component may index early visual feature extraction in response to bivalent stimuli that cue currently ongoing tasks; dACC activity may trigger the temporal parietal activity only when specific task cueing is involved and not for simple violations of expectancy. PMID:24686093

  7. Corticotropin-releasing Factor in the Rat Dorsal Raphe Nucleus Promotes Different Forms of Behavioral Flexibility Depending on Social Stress History.

    PubMed

    Snyder, Kevin P; Hill-Smith, Tiffany E; Lucki, Irwin; Valentino, Rita J

    2015-10-01

    The stress-related neuropeptide, corticotropin-releasing factor (CRF) regulates the dorsal raphe nucleus-serotonin (DRN-5-HT) system during stress and this may underlie affective and cognitive dysfunctions that characterize stress-related psychiatric disorders. CRF acts on both CRF1 and CRF2 receptor subtypes in the DRN that exert opposing inhibitory and excitatory effects on DRN-5-HT neuronal activity and 5-HT forebrain release, respectively. The current study first assessed the cognitive effects of intra-DRN microinfusion of CRF or the selective CRF2 agonist, urocortin II in stress-naive rats on performance of an operant strategy set-shifting task that is mediated by the medial prefrontal cortex (mPFC). CRF (30 ng) facilitated strategy set-shifting performance, whereas higher doses of CRF and urocortin II that would interact with CRF2 were without effect, consistent with a CRF1-mediated action. This dose decreased 5-HT extracellular levels in the mPFC, further supporting a role for CRF1. The effects of CRF were then assessed in rats exposed to repeated social stress using the resident-intruder model. Repeated social stress shifted the CRF effect from facilitation of strategy set shifting to facilitation of reversal learning and this was most prominent in a subpopulation of rats that resist defeat. Notably, in this subpopulation of rats 5-HT neuronal responses to CRF have been demonstrated to shift from CRF1-mediated inhibition to CRF2-mediated excitation. Because 5-HT facilitates reversal learning, the present results suggest that stress-induced changes in the cellular effects of CRF in the DRN translate to changes in cognitive effects of CRF. Together, the results underscore the potential for stress history to shift cognitive processing through changes in CRF neurotransmission in the DRN and the association of this effect with coping strategy. PMID:25865931

  8. Family History

    MedlinePlus

    Your family history includes health information about you and your close relatives. Families have many factors in common, including their genes, ... as heart disease, stroke, and cancer. Having a family member with a disease raises your risk, but ...

  9. Temporal variation in life-history traits of the clam Tivela mactroides (Bivalvia: Veneridae): Density-dependent processes in sandy beaches

    NASA Astrophysics Data System (ADS)

    Turra, Alexander; Petracco, Marcelo; Amaral, A. Cecilia Z.; Denadai, Márcia R.

    2014-10-01

    Temporal variation in the structure and dynamics of a population of Tivela mactroides was examined over two periods (2003-2004 and 2007-2008) in the southern part of Caraguatatuba Bay, southeastern Brazil. During the first period from January 2003 to October 2004, sampling was conducted monthly. Sampling in the second period was performed in the summer (January and February 2007 and 2008) and winter (July and August 2007 and 2008). The von Bertalanffy growth function was applied to estimate growth parameters for both periods from length-frequency distributions. Production was determined using the mass-specific growth rate method. Results indicated that the mean abundance (±SE) of T. mactroides varied sharply between the two periods, with an increase of almost 150 times from 2003 to 2004 (8.67·102 ± 0.83·102 ind m-1) to 2007-2008 (1.25·105 ± 3.33·104 ind m-1). The higher abundance in the second period was related to successful recruitment events. While the mean biomass and the production were higher in the second (5.43 ± 0.87 kg AFDM m-1 and 7.89 kg AFDM m-1 yr-1) than in the first period (0.18 ± 0.02 kg AFDM m-1 and 0.18 kg AFDM m-1 yr-1), lower values of shell length, curvature parameter, asymptotic length of the VBGF, and the growth index phi-prime in 2007-2008 (17.57 ± 1.35 mm; K = 0.40 yr-1; L∞ = 38.60 mm, ϕ‧ = 2.78) than in 2003-2004 (26.21 ± 1.21 mm; K = 1.00 yr-1; L∞ = 40.75 mm, ϕ‧ = 3.22) were related to a strongly density-dependent growth process in the second period. The oscillation in growth observed in the second, but not in the first period also indicates a process of density-dependent growth. These sharp temporal variations in population parameters of T. mactroides suggest the occurrence of density-dependent processes, and reinforce the importance of these processes in structuring sandy-beach populations.

  10. A history of chronic morphine exposure during adolescence increases despair-like behaviour and strain-dependently promotes sociability in abstinent adult mice

    PubMed Central

    Lutz, PE; Reiss, D; Ouagazzal, AM; Kieffer, BL

    2013-01-01

    A crucial issue in treating opiate addiction, a chronic relapsing disorder, is to maintain a drug-free abstinent state. Prolonged abstinence associates with mood disorders, strongly contributing to relapse. In particular, substance use disorders occurring during adolescence predispose to depression later in adulthood. Using our established mouse model of opiate abstinence, we characterized emotional consequences into adulthood of morphine exposure during adolescence. Our results indicate that morphine treatment in adolescent mice has no effect on anxiety-like behaviours in adult mice, after abstinence. In contrast, morphine treatment during adolescence increases behavioural despair in adult mice. We also show that morphine exposure strain-dependently enhances sociability in adult mice. Additional research will be required to understand where and how morphine acts during brain maturation to affect emotional and social behaviours into adulthood. PMID:23295400

  11. Natural History of Dependency in the Elderly: A 24-Year Population-Based Study Using a Longitudinal Item Response Theory Model.

    PubMed

    Edjolo, Arlette; Proust-Lima, Cécile; Delva, Fleur; Dartigues, Jean-François; Pérès, Karine

    2016-02-15

    We aimed to describe the hierarchical structure of Instrumental Activities of Daily Living (IADL) and basic Activities of Daily Living (ADL) and trajectories of dependency before death in an elderly population using item response theory methodology. Data were obtained from a population-based French cohort study, the Personnes Agées QUID (PAQUID) Study, of persons aged ≥65 years at baseline in 1988 who were recruited from 75 randomly selected areas in Gironde and Dordogne. We evaluated IADL and ADL data collected at home every 2-3 years over a 24-year period (1988-2012) for 3,238 deceased participants (43.9% men). We used a longitudinal item response theory model to investigate the item sequence of 11 IADL and ADL combined into a single scale and functional trajectories adjusted for education, sex, and age at death. The findings confirmed the earliest losses in IADL (shopping, transporting, finances) at the partial limitation level, and then an overlapping of concomitant IADL and ADL, with bathing and dressing being the earliest ADL losses, and finally total losses for toileting, continence, eating, and transferring. Functional trajectories were sex-specific, with a benefit of high education that persisted until death in men but was only transient in women. An in-depth understanding of this sequence provides an early warning of functional decline for better adaptation of medical and social care in the elderly. PMID:26825927

  12. The way to her heart? Response to romantic cues is dependent on hunger state and dieting history: An fMRI pilot study.

    PubMed

    Ely, Alice V; Childress, Anna Rose; Jagannathan, Kanchana; Lowe, Michael R

    2015-12-01

    Normal weight historical dieters (HDs) are prone to future weight gain, and show higher levels of brain activation in reward-related regions after having eaten than nondieters (NDs) in response to food stimuli (Ely, Childress, Jagannathan, & Lowe, 2014), a similar pattern to that seen in obesity. We hypothesized that HDs are differentially sensitive after eating to rewards in general, and thus extended prior findings by comparing the same groups' brain activation when viewing romantic pictures compared to neutral stimuli while being scanned in a blood oxygenation level-dependent (BOLD) fMRI paradigm in a fasted and fed state. Results show that 1) in fed relative to fasted conditions, both HDs and NDs were more responsive in areas related to reward and 2) in HDs, greater fed versus fasted activation extended to areas linked to perception and goal-directed behavior. HDs relative to NDs were more responsive to romantic cues in the superior frontal gyrus when fasted and the middle temporal gyrus when fed. This pattern of response is similar to HDs' activation when viewing highly palatable food cues, and is consistent with research showing overlapping brain-based responses to sex, drugs and food. PMID:26145276

  13. Lunar History

    NASA Technical Reports Server (NTRS)

    Edmunson, Jennifer E.

    2009-01-01

    This section of the workshop describes the history of the moon, and offers explanations for the importance of understanding lunar history for engineers and users of lunar simulants. Included are summaries of the initial impact that is currently in favor as explaining the moon's formation, the crust generation, the creation of craters by impactors, the era of the lunar cataclysm, which some believe effected the evolution of life on earth, the nature of lunar impacts, crater morphology, which includes pictures of lunar craters that show the different types of craters, more recent events include effect of micrometeorites, solar wind, radiation and generation of agglutinates. Also included is a glossary of terms.

  14. Bulletproof History.

    ERIC Educational Resources Information Center

    Roy, R. H.

    1994-01-01

    Asserts that the writers and producers of the television documentary, "The Valour and the Horror," provided a false impression of an event to fit preconceived and erroneous interpretations of history. Points out specific examples of inaccurate historical presentations and provides contradictory historical interpretations. (CFR)

  15. Arguing History

    ERIC Educational Resources Information Center

    Clary, Renee; Wandersee, James

    2013-01-01

    The history of science illustrates some exciting--and sometimes controversial--moments. Unfortunately, textbooks tend to focus on results in a scientific discipline and only occasionally showcase an interesting historical vignette, telling the story behind those results. Although required studies may leave teachers little classroom time for…

  16. Making History

    ERIC Educational Resources Information Center

    Shein, Esther

    2008-01-01

    Jennifer Dorman was in a fix. Teaching ninth-grade US history at Holicong Middle School in Doylestown, Pennsylvania, Dorman wanted to tap into her students' interest in creating "something of value not just for their teachers, but something they could share with other students and people." But that required something a conventional paper-based…

  17. River history.

    PubMed

    Vita-Finzi, Claudio

    2012-05-13

    During the last half century, advances in geomorphology-abetted by conceptual and technical developments in geophysics, geochemistry, remote sensing, geodesy, computing and ecology-have enhanced the potential value of fluvial history for reconstructing erosional and depositional sequences on the Earth and on Mars and for evaluating climatic and tectonic changes, the impact of fluvial processes on human settlement and health, and the problems faced in managing unstable fluvial systems. PMID:22474674

  18. Uncovering History for Future History Teachers

    ERIC Educational Resources Information Center

    Fischer, Fritz

    2010-01-01

    The art of history teaching is at a crossroads. Recent scholarship focuses on the need to change the teaching of history so students can better learn history, and insists that history teachers must move beyond traditional structures and methods of teaching in order to improve their students' abilities to think with history. This article presents…

  19. Virtual History and the History of Education.

    ERIC Educational Resources Information Center

    McCulloch, Gary

    2003-01-01

    Discusses three potential problems in the application of virtual history: (1) extrapolation; (2) critical analysis; and (3) the danger of using it as wishful thinking. Offers comparative history as a possible alternative way to overcome virtual history outcomes. (KDR)

  20. The GAO History Program: A History.

    ERIC Educational Resources Information Center

    Trask, Roger R.

    1991-01-01

    Discusses the planning, formation, and history of the General Accounting Office history program. Addresses functions, staff size, organizational placement, and the role of an advisory committee. Stresses oral history, policy research, and identification of documentary sources. (DK)

  1. Cygnus History

    SciTech Connect

    David J. Henderson, Raymond E. Gignac, Douglas E. Good, Mark D. Hansen, Charles V. Mitton; Daniel S. Nelson, Eugene C. Ormond; Steve R. Cordova, Isidro Molina; John R. Smith, Evan A. Rose

    2009-07-02

    The Cygnus Dual Beam Radiographic Facility consists of two identical radiographic sources: Cygnus 1 and Cygnus 2. This Radiographic Facility is located in an underground tunnel test area at the Nevada Test Site. The sources were developed to produce high-resolution images for dynamic plutonium experiments. This work will recount and discuss salient maintenance and operational issues encountered during the history of Cygnus. A brief description of Cygnus systems and rational for design selections will set the stage for this historical narrative. It is intended to highlight the team-derived solutions for technical problems encountered during extended periods of maintenance and operation. While many of the issues are typical to pulsed power systems, some of the solutions are unique. It is hoped that other source teams will benefit from this presentation, as well as other necessary disciplines (e.g., source users, system architects, facility designers and managers, funding managers, and team leaders).

  2. Natural history and the Encyclopedie.

    PubMed

    Llana, J

    2000-01-01

    The general popularity of natural history in the eighteenth century is mirrored in the frequency and importance of the more than 4,500 articles on natural history in the Encyclopedie. The main contributors to natural history were Daubenton, Diderot, Jaucourt and d'Holbach, but some of the key animating principles derive from Buffon, who wrote nothing specifically for the Encyclopedie. Still, a number of articles reflect his thinking, especially his antipathy toward Linnaeus. There was in principle a natural tie between encyclopedism, with its emphasis on connected knowledge, and the task of natural historians who concentrated on the relationships among living forms. Both the encyclopedists and the natural historians aimed at a sweeping overview of knowledge, and we see that Diderot's discussions of the encyclopedia were apparently informed by his reading of natural history. Most of the articles on natural history drew from traditional sources, but there are differences in emphasis and choice of subject, depending upon the author. Diderot's 300 contributions are often practical, interesting, and depend upon accounts from other parts of the world. Jaucourt, who wrote more articles on natural history than anyone else, followed in his foodsteps. Daubenton's 900 articles reflected a more narrow, professional approach. His contributions concluded for the most part with Volume 8, and Jaucourt carried on almost single-handedly after that. While staking out traditional ground (description, taxonomy) and advancing newer theoretical views linked with Buffon, natural history in the Encyclopedie avoided almost completely the sentimentalism concerning nature that developed after Rousseau. PMID:11624414

  3. The Future of History and History Teaching.

    ERIC Educational Resources Information Center

    Commager, Henry Steele

    1983-01-01

    Technical history, a quantitative record of history strengthened by new techniques in mathematics, computer science, and other fields has advantages over former approaches to history--history as philosophy and historical theology. For example, it makes available more source materials. However, it has drawbacks, e.g., it directs research to highly…

  4. Ras history

    PubMed Central

    2010-01-01

    Although the roots of Ras sprouted from the rich history of retrovirus research, it was the discovery of mutationally activated RAS genes in human cancer in 1982 that stimulated an intensive research effort to understand Ras protein structure, biochemistry and biology. While the ultimate goal has been developing anti-Ras drugs for cancer treatment, discoveries from Ras have laid the foundation for three broad areas of science. First, they focused studies on the origins of cancer to the molecular level, with the subsequent discovery of genes mutated in cancer that now number in the thousands. Second, elucidation of the biochemical mechanisms by which Ras facilitates signal transduction established many of our fundamental concepts of how a normal cell orchestrates responses to extracellular cues. Third, Ras proteins are also founding members of a large superfamily of small GTPases that regulate all key cellular processes and established the versatile role of small GTP-binding proteins in biology. We highlight some of the key findings of the last 28 years. PMID:21686117

  5. Reduced regional cerebral blood flow in aged noninsulin-dependent diabetic patients with no history of cerebrovascular disease: evaluation by N-isopropyl- sup 123 I-p-iodoamphetamine with single-photon emission computed tomography

    SciTech Connect

    Wakisaka, M.; Nagamachi, S.; Inoue, K.; Morotomi, Y.; Nunoi, K.; Fujishima, M. )

    1990-10-01

    Regional cerebral blood flow was measured using N-isopropyl-{sup 123}I-iodoamphetamine with single-photon emission computed tomography (CT) in 16 aged patients with noninsulin-dependent diabetes mellitus (NIDDM, average age 72.8 years, average fasting plasma glucose 7.7 mmol/L), and 12 nondiabetic subjects (71.6 years, 5.3 mmol/L). None had any history of a cerebrovascular accident. Systolic blood pressure (SBP), total cholesterol, and triglyceride levels did not differ between groups. Areas of hypoperfusion were observed in 14 diabetic patients (12 patients had multiple lesions) and in 6 nondiabetic subjects (3 had multiple lesions). Areas where radioactivity was greater than or equal to 65% of the maximum count of the slice was defined as a region with normal cerebral blood flow (region of interest A, ROI-A), and areas where the count was greater than or equal to 45% were defined as brain tissue regions other than ventricles (ROI-B). The average ROI-A/B ratio of 16 slices was used as a semiquantitative indicator of normal cerebral blood flow throughout the entire brain. Mean ROI-A/B ratio was 49.6 +/- 1.7% in the diabetic group, significantly lower than the 57.9 +/- 1.6% at the nondiabetic group (p less than 0.005). The ratio was inversely correlated with SBP (r = -0.61, p less than 0.05), total cholesterol (r = -0.51, p less than 0.05), and atherogenic index (r = -0.64, p less than 0.01), and was positively correlated with high-density lipoprotein (HDL) cholesterol (r = 0.51, p less than 0.05) in the diabetic, but not the nondiabetic group. These observations suggest that the age-related reduction in cerebral blood flow may be accelerated by a combination of hyperglycemia plus other risk factors for atherosclerosis.

  6. KSC History Project

    NASA Technical Reports Server (NTRS)

    Dethloff, Henry C.

    2001-01-01

    The KSC History Project focuses on archival research and oral history interviews on the history of Kennedy Space Center (KSC). Related projects include the preparation of a precis and chapter outline for a proposed book-length narrative history, a bibliography of key primary and secondary resources, a brief monograph overview of the history of KSC, and a monograph on the history of safety at the Center. Finally, there is work on the development of a web page and a personal history data base associated with the oral history project. The KSC History Project has been a joint endeavor between Henry C. Dethloff and Dr. Noble Lee Snaples, Jr.

  7. History of Geology.

    ERIC Educational Resources Information Center

    Greene, Mott T.

    1985-01-01

    Discusses: (1) geologists and the history of geology; (2) American historians and the history of geology; (3) history of geology in the 1980s; (4) sources for the history of geology (bibliographies, dictionaries, encyclopedias, handbooks, periodicals, public/official histories, compilations, and books); (5) research opportunities; and (6) other…

  8. The Rhetorical Force of History in Public Argument.

    ERIC Educational Resources Information Center

    Schwartzman, Roy

    The rhetorical functions of history depend on the domain in which history is used, with no connotations of interpretive priority attaching to the social or the academic realm. The appropriation of history in support of social causes as radically opposed as socialism and fascism fuels the temptation to subsume history under ideology, with the…

  9. Dependent Probability Spaces

    ERIC Educational Resources Information Center

    Edwards, William F.; Shiflett, Ray C.; Shultz, Harris

    2008-01-01

    The mathematical model used to describe independence between two events in probability has a non-intuitive consequence called dependent spaces. The paper begins with a very brief history of the development of probability, then defines dependent spaces, and reviews what is known about finite spaces with uniform probability. The study of finite…

  10. What Is Literary "History"?

    ERIC Educational Resources Information Center

    Harris, Wendell V.

    1994-01-01

    Examines the meaning of the word "history" as used in the common phrase "literary history" by critics and scholars. Asserts the differences between historical scholarship and literary history. Argues that the grounding activity of literary history is insulated from the relativism insisted upon by poststructuralist theorizing. (HB)

  11. History Circles: The Doing of Teaching History

    ERIC Educational Resources Information Center

    Brown, Sarah Drake

    2009-01-01

    Lesson planning is a critical task in the education of pre-service teachers, but the author has often questioned the extent to which traditional lesson plan formats truly contribute to the teaching and learning of history. Since current research in history education calls for an emphasis on building "historical thinking" skills and content…

  12. Classical Histories in Hamiltonian Systems

    NASA Astrophysics Data System (ADS)

    Kouletsis, Ioannis

    2001-08-01

    The incompatibility between the treatment of time in the classical and in the quantum theory results in the so-called problem of time in canonical quantum gravity. For this reason, attempts have been made to devise algorithms of quantization which accomodate the covariance of the classical theory from the outset. One of the most prominent of these attempts is based on the notion of continuous histories (Isham and Linden) in the context of the consistent histories approach to quantum theory (Griffiths, Omnes, Gell-Mann and Hartle). By the term continuous histories it is implied that the canonical fields and the symplectic structure of the theory depend on time as well as space. The aim of this thesis (in the form it was submitted to the University of London, February 2000) is to show that, even at the purely classical level, a history approach has several advantages (compared to its equal-time counterpart) when it comes to discussing spacetime issues. This is illustrated here by reframing and generalizing the derivation of geometrodynamics from first principles (Hojman, Kuchar, Teitelboim) in the language of the history phase space.

  13. HAD Oral History Project

    NASA Astrophysics Data System (ADS)

    Holbrook, Jarita

    2014-01-01

    The Historical Astronomy Division is the recipient of an American Institute of Physics Neils Bohr Library Grant for Oral History. HAD has assembled a team of volunteers to conduct oral history interviews since May 2013. Each oral history interview varies in length between two and six hours. This presentation is an introduction to the HAD Oral History Project and the activities of the team during the first six months of the grant.

  14. KSC History Project

    NASA Technical Reports Server (NTRS)

    Snaples, Lee

    2001-01-01

    The project is a joint endeavor between Dr. Henry Dethloff and myself and is producing a number of products related to KSC history. This report is a summary of those projects. First, there is an overview monograph covering KSC history. Second, there is a chapter outline for an eventual book-length history. Third, there is monograph on safety at KSC. Finally, there is a web page and database dedicated to the KSC oral history project.

  15. Studying Ancient History.

    ERIC Educational Resources Information Center

    Barrow, Robin

    1982-01-01

    Defends the value and relevance of the study of ancient history and classics in history curricula. The unique homogeneity of the classical period contributes to its instructional manageability. A year-long, secondary-level course on fifth-century Greece and Rome is described to illustrate effective approaches to teaching ancient history. (AM)

  16. Film and History.

    ERIC Educational Resources Information Center

    Schaber, Robin L.

    2002-01-01

    Provides an annotated bibliography of Web sites that focus on using film to teach history. Includes Web sites in five areas: (1) film and education; (2) history of cinema; (3) film and history resources; (4) film and women; and (5) film organizations. (CMK)

  17. Conducting the Medical History

    ERIC Educational Resources Information Center

    Finkel, Martin A.; Alexander, Randell A.

    2011-01-01

    A key portion of the medical evaluation of child sexual abuse is the medical history. This differs from interviews or histories obtained by other professionals in that it is focuses more on the health and well-being of the child. Careful questions should be asked about all aspects of the child's medical history by a skilled, compassionate,…

  18. The Trouble with History.

    ERIC Educational Resources Information Center

    Myers, John

    1990-01-01

    Cites the problems associated with teaching history: (1) lack of consensus on what and how to teach; (2) the adult perspective from which it is taught; (3) the abstract nature of history content; and (4) the concept of time. Concludes that efforts to include adolescent knowledge, skills, and attitudes should be considered in the history program.…

  19. History of Physics.

    ERIC Educational Resources Information Center

    Moyer, Albert E.

    1985-01-01

    Discusses the history of American physics, indicating that much effort has been on the atomic bond and high-energy physics, to the detriment of other topics and areas. To offset this tendency, significant research is going on in the history of solid-state physics, with glimmerings in the history of physics education. (JN)

  20. Who Owns History?

    ERIC Educational Resources Information Center

    Hackney, Sheldon

    1995-01-01

    Presents an interview with historian Cary Carson of the Colonial Williamsburg Foundation and author William Styron on the role of history in society. Outlines the once-proposed Disney history theme park near Mannassas, Virginia. Discusses historical interpretation, museums, historical sites, and popular history. (CFR)

  1. History of Science and History of Philologies.

    PubMed

    Daston, Lorraine; Most, Glenn W

    2015-06-01

    While both the sciences and the humanities, as currently defined, may be too heterogeneous to be encompassed within a unified historical framework, there is good reason to believe that the history of science and the history of philologies both have much to gain by joining forces. This collaboration has already yielded striking results in the case of the history of science and humanist learning in early modern Europe. This essay argues that first, philology and at least some of the sciences (e.g., astronomy) remained intertwined in consequential ways well into the modern period in Western cultures; and second, widening the scope of inquiry to include other philological traditions in non-Western cultures offers rich possibilities for a comparative history of learned practices. The focus on practices is key; by shifting the emphasis from what is studied to how it is studied, deep commonalities emerge among disciplines--and intellectual traditions--now classified as disparate. PMID:26353442

  2. Diet History Questionnaire: Database Revision History

    Cancer.gov

    The following details all additions and revisions made to the DHQ nutrient and food database. This revision history is provided as a reference for investigators who may have performed analyses with a previous release of the database.

  3. Between Political History and Historical Politics: Fundamental Forms of Historical and Political Literacy

    ERIC Educational Resources Information Center

    Lange, Dirk

    2006-01-01

    Politics without history has no roots; history without politics bears no fruits. If one inquires into the content of the relation between politics and history, then one discovers it is defined by symbiotic dependence. Those who are trained in history also take into account the political dimensions of history, and those educated in political…

  4. KSC History Project

    NASA Technical Reports Server (NTRS)

    Moore, Patrick K.

    2003-01-01

    The 2003 NASA/ASEE KSC History Project focused on a series of six history initiatives designed to acquire, preserve, and interpret the history of Kennedy Space Center. These six projects included the completion of Voices From the Cape, historical work co-authored with NASA historian Roger Launius, the completion of a series of oral histories with key KSC personnel, expansion of monograph on Public Affairs into two comprehensive pieces on KSC press operations and KSC visitor operations, the expansion of KSC Historical Concept Maps (Cmap) for history knowledge preservation, the expansion of the KSC oral history program through the administration of an oral history workshop for KSC-based practitioners, and the continued collaborative relationships between Kennedy Space Center, the University of West Florida, the University of Central Florida and other institutions including the University of Louisiana at Lafayette.

  5. KSC History Project

    NASA Technical Reports Server (NTRS)

    Moore, Patrick K.

    2002-01-01

    The 2002 NASA/ASEE KSC History Project focused on a series of seven history initiatives designed to acquire, preserve, and interpret the history of Kennedy Space Center. These seven projects included the co-authoring of Voices From the Cape, historical work with NASA historian Roger Launius, the completion of a series of oral histories with key KSC personnel, a monograph on Public Affairs, the development of a Historical Concept Map (CMap) for history knowledge preservation, advice on KSC history database and web interface capabilities, the development of a KSC oral history program and guidelines of training and collection, and the development of collaborative relationships between Kennedy Space Center, the University of West Florida, and the University of Central Florida.

  6. Recent Writings in Social History.

    ERIC Educational Resources Information Center

    Cross, Michael S.

    1979-01-01

    Reviews current writings relevant to teaching the social history of Canada. Subjects addressed are social protest and conflict, labor history, working class history, women, the city, intellectual history, and regional studies. (KC)

  7. [History of Polish pharmacy].

    PubMed

    Okuda, J; Okuda, R

    1993-01-01

    Doctoral thesis (in French) by Monika Debska-Donnet, entitled "History of pharmacy and pharmaceutical art collections in Poland" which was presented to Paris XI University (Faculty of Pharmaceutical and Biological Sciences) in 1991, was translated into Japanese and summarized. In this report, histories of pharmacy education, pharmacists, community pharmacies, pharmacopoeiae, pharmaceutical industries in Poland were described, and four representative Polish museums of history of pharmacy were also explained. PMID:11639718

  8. American History Activators (Early American History).

    ERIC Educational Resources Information Center

    Lacey, Bill

    This document consists of a package of seven separately published "activities" or simulations that allow students to learn about and participate in many of the aspects of United States history that have influenced our present institutions and way of life. The seven units include: (1) First Americans Arrive: 11.000 BC; (2) Puritan General Court,…

  9. Teaching History: The Fax about History

    ERIC Educational Resources Information Center

    Bryant, James A., Jr.

    2005-01-01

    Social studies and history have taken a back seat to other subjects in recent years, but the author argues that there is far too much at stake to allow these important fields to become irrelevant. To drive home the point, in this article, he shares a story about the 9/11 Commission, that made headlines in 2004.

  10. History of Science

    ERIC Educational Resources Information Center

    Oversby, John

    2010-01-01

    In this article, the author discusses why the history of science should be included in the science curriculum in schools. He also presents some opportunities that can come out of using historical contexts, and findings from a study assessing the place of history of science in readily available textbooks.

  11. Women's History Curriculum Guide.

    ERIC Educational Resources Information Center

    Ruthsdotter, Mary, Ed.; Eisenberg, Bonnie, Ed.

    This curriculum guide is designed to facilitate teachers' first efforts to introduce information about women in U.S. history. The guide promotes a multicultural awareness of women's history beginning with the Native Americans and proceeding to current issues of diversity. Activities are divided for grades 1-6 and 7-12 but may be adapted as…

  12. Is World History Teachable?

    ERIC Educational Resources Information Center

    Dunn, Ross E.

    1988-01-01

    Discusses the views of Paul Gagnon and his book "Democracy's Untold Story." Examines the drawbacks of teaching the type of Western civilization course advocated by Gagnon and argues that schools should continue the quest for a teachable approach to world history. Includes suggestions for improving the typical world history course. (GEA)

  13. Implementing Big History.

    ERIC Educational Resources Information Center

    Welter, Mark

    2000-01-01

    Contends that world history should be taught as "Big History," a view that includes all space and time beginning with the Big Bang. Discusses five "Cardinal Questions" that serve as a course structure and address the following concepts: perspectives, diversity, change and continuity, interdependence, and causes. (CMK)

  14. Family History Resources.

    ERIC Educational Resources Information Center

    Bookmark, 1991

    1991-01-01

    The 12 articles in this issue focus on the theme of family history resources: (1) "Introduction: Family History Resources" (Joseph F. Shubert); (2) "Work, Credentials, and Expectations of a Professional Genealogist" (Coreen P. Hallenbeck and Lewis W. Hallenbeck); (3) "Computers and Genealogy" (Theresa C. Strasser); (4) "Finding Historical Records…

  15. Homes in History.

    ERIC Educational Resources Information Center

    Ohrn, Deborah Gore, Ed.

    1993-01-01

    This issue of "The Goldfinch," an Iowa history magazine for children, focuses on issues relating to housing. Articles address such subjects as homelessness, neighborhood history, architecture, and local folklore. One student activity is the "Building Blocks" game that calls upon students to fill in blanks to complete words from the issue relating…

  16. Researching Your Department's History

    ERIC Educational Resources Information Center

    Fasl, Patrick J.

    2008-01-01

    In the spirit of the fiftieth anniversary of IACLEA, the author proposes that every campus law enforcement agency conduct an extensive examination for the purpose of documenting their history. After spending many hours online the author discovered that only a few departments have taken time to write their history and no doubt there are a multitude…

  17. Preaching in American History.

    ERIC Educational Resources Information Center

    Holland, DeWitte, Ed.

    This volume of twenty essary by nineteen authors attempts to describe the message, issues, and impact of American preaching as it has interacted with history and shaped American churches and society. The twenty topics, treated by individuals with advanced degrees in theology or speech, are: the role of preaching in American history; Puritan…

  18. Microscale acceleration history discriminators

    DOEpatents

    Polosky, Marc A.; Plummer, David W.

    2002-01-01

    A new class of micromechanical acceleration history discriminators is claimed. These discriminators allow the precise differentiation of a wide range of acceleration-time histories, thereby allowing adaptive events to be triggered in response to the severity (or lack thereof) of an external environment. Such devices have applications in airbag activation, and other safety and surety applications.

  19. Teaching Nuclear History.

    ERIC Educational Resources Information Center

    Holl, Jack M.; Convis, Sheila C.

    1991-01-01

    Presents results of a survey of the teaching about nuclear history at U.S. colleges and universities. Reports the existence of a well-established and extensive literature, a focus on nuclear weapons or warfare, and a concentration on nuclear citizenship, therapy, or eschatology for courses outside of history departments. Discusses individual…

  20. Rethinking TV History.

    ERIC Educational Resources Information Center

    Gomery, Douglas

    1997-01-01

    Proposes a rethinking of historical analysis of U. S. television history, to begin at the local level. Offers a case study of the place of Washington, DC, as a site for network news. Notes that, as a community, Washington presents an important site where forces such as migration and suburbanization shaped the early history of television. (SR)

  1. History of reinforced plastics

    SciTech Connect

    Milewski, J.V.; Rosato, D.V.

    1981-01-01

    This history of reinforced plastics is told by combining the individual histories of each reinforcement and the way in which they added to and changed the direction and rate of growth of the industry. The early history is based on all resins, fillers, and fibers found in nature. Then came the Baekeland revolution with the first synthetic resin which lasted about 25 years, at which time synthetic fiber glass and polyester resin dramatically changed the industry. Now, for the 1980s, the high modulus fibers developed 10 to 20 years ago are reshaping the industry. 32 figures.

  2. History of Hydrology

    NASA Astrophysics Data System (ADS)

    As George Sarton, generally acknowledged to be the father of the history of science, so elegantly stated, scientific endeavors and understanding are cumulative in nature. Thus it seems appropriate that scientists within a given discipline should occasionally take a backward glance and examine their heritage. With such a view, a series of AGU symposia were organized, beginning in December 1984, to deal with the history of hydrology. Fifteen papers, largely from the first two such sessions, have been compiled as a special volume of the History of Geophysics Series.

  3. The Oral History Review, 1975.

    ERIC Educational Resources Information Center

    Hand, Samuel B., Ed.

    The contents of this issue of the "Oral History Review" include eight articles, Oral History Council reports, and lists of the sites of future oral history colloquiums, of Oral History Association publications in print and in microform, and of contributors. Titles of articles and authors are as follows: "Oral History Comes of Age" by Samuel…

  4. Collecting and Using Local History.

    ERIC Educational Resources Information Center

    Miller, Marcia Muth

    The local history collection should contain: county histories; city and village histories; state and regional histories; anniversary booklets; company histories; local newspapers; local magazines; genealogies; family albums; diaries; journals, and letters; account books; club yearbooks; school annuals; telephone books, city directories and local…

  5. Suicidal Behavior in Chemically Dependent Adolescents.

    ERIC Educational Resources Information Center

    Cavaiola, Alan A.; Lavender, Neil

    1999-01-01

    Study explores distinctions between chemically dependent suicide attempters, chemically dependent nonsuicidal adolescents, and high school students with no history of chemical dependency (N=250). Results reveal that there were significant differences between the chemically dependent groups. It was also found that the majority of suicidal gestures…

  6. The development of a regional nursing history collection: its relevance to practice, education, and research.

    PubMed

    Hezel, L F; Linebach, L M

    1991-01-01

    The future of nursing may well depend on the study of its history. Because the study of history is so important to nurses today, the Nursing History Committee was formed to collect, protect, and maintain significant information. The Nursing Heritage Foundation, an outgrowth of this committee, established the Nursing History Collection at the University of Missouri-Kansas City. PMID:1798665

  7. Singing American History.

    ERIC Educational Resources Information Center

    Nielsen, Fred

    2001-01-01

    Discusses how to use music when teaching U.S. History. Provides examples such as teaching about the Civil War, the Great Depression, and the Vietnam War and showing the contributions of African Americans. Includes a discography. (CMK)

  8. History and Legacy

    ERIC Educational Resources Information Center

    Mason, Diana S.

    2004-01-01

    The history of the computer usage in high school laboratories is discussed. Students learned scientific methods by acknowledging measurement errors, using significant digits, questioning their own results, and without doubts, they benefited from applying skill learned in mathematics classes.

  9. History of Chiropractic Care

    MedlinePlus

    ... Districts Public Policies Committees American Chiropractic Foundation Elections Origins and History of Chiropractic Care The word ‘Chiropractic’ ... chiropractic as a health care profession. Many other countries also recognize and regulate chiropractic, including Canada, Mexico, ...

  10. History of Stellar Interferometry

    NASA Technical Reports Server (NTRS)

    Lawson, Peter R.

    2004-01-01

    This viewgraph presentation reviews the history of stellar interferometry from the suggestion of Fizeau that stellar interferometry was possible,to the use of the Mark I, II and III for astrometry. Photographs, and parts of original articles are presented.

  11. History Begins at Home

    ERIC Educational Resources Information Center

    McCully, George E.

    1978-01-01

    Suggests that high school history can be more interesting and useful if students are taught to formulate, evaluate, and use historical statements on the basis of evidence available in primary sources. Outlines a curriculum based on this thesis. (AV)

  12. Living history biography

    SciTech Connect

    Puck, T.T.

    1994-11-15

    A living history biography is presented of Theodore T. Puck. This history is intimately involved with the progress towards mapping of the human genome through research at the forefront of molecular cytogenetics. A review of historical research aims such as human genetics studies based on somatic cells, isolation of mutants as genetic markers, complementation analysis, gene mapping and the measurement of mutation is presented. 37 refs., 4 figs.

  13. AAS Oral History Project

    NASA Astrophysics Data System (ADS)

    Buxner, Sanlyn; Holbrook, Jarita; AAS Oral History Team

    2016-06-01

    Now in its fourth year, the AAS Oral History Project has interviewed over 80 astronomers from all over the world. Led by the AAS Historical Astronomy Division (HAD) and partially funded by the American Institute of Physics Niels Bohr Library and ongoing support from the AAS, volunteers have collected oral histories from astronomers at professional meetings starting in 2015, including AAS, DPS, and the IAU general assembly. Each interview lasts one and a half to two hours and focuses on interviewees’ personal and professional lives. Questions include those about one’s family, childhood, strong influences on one’s scientific career, career path, successes and challenges, perspectives on how astronomy is changing as a field, and advice to the next generation. Each interview is audio recorded and transcribed, the content of which is checked with each interviewee. Once complete, interview transcripts are posted online as part of a larger oral history library at https://www.aip.org/history-programs/niels-bohr-library/oral-histories. Future analysis will reveal a rich story of astronomers and will help the community address issues of diversity, controversies, and the changing landscape of science. We are still recruiting individuals to be interviewed from all stages of career from undergraduate students to retired and emeritus astronomers. Contact Jarita Holbrook to schedule an interview or to find out more information about the project (astroholbrook@gmail.com). Also, contact Jarita Holbrook if you would like to become an interviewer for the project.

  14. Investigating human evolutionary history

    PubMed Central

    WOOD, BERNARD

    2000-01-01

    We rely on fossils for the interpretation of more than 95% of our evolutionary history. Fieldwork resulting in the recovery of fresh fossil evidence is an important component of reconstructing human evolutionary history, but advances can also be made by extracting additional evidence for the existing fossil record, and by improving the methods used to interpret the fossil evidence. This review shows how information from imaging and dental microstructure has contributed to improving our understanding of the hominin fossil record. It also surveys recent advances in the use of the fossil record for phylogenetic inference. PMID:10999269

  15. History of hydrology archive

    NASA Astrophysics Data System (ADS)

    Back, William

    There has long been concern over how to archive important material related to the history of hydrology. Bill Back (U.S. Geological Survey, Reston, Va.), past chairman of the AGU Committee on History and Heritage of Hydrology, has made contact with the American Heritage Center, which has been collecting such material for nearly 20 years. They now have an expanding program and are most enthusiastic about helping us preserve historical material. They would like to receive files, manuscripts, photographs, and similar material from hydrologists throughout the United States and other countries.

  16. History of psychology.

    PubMed

    Weidman, Nadine

    2016-02-01

    The editor of History of Psychology discusses her plan to vary the journal's content and expand its scope in specific ways. The first is to introduce a "Spotlight" feature, a relatively brief, provocative thought piece that might take one of several forms. Along with this new feature, she hopes further to broaden the journal's coverage and its range of contributors. She encourages submissions on the history of the psy-sciences off the beaten path. Finally, she plans to continue the journal's tradition of special issues, special sections, and essay reviews of two or more important recently published books in the field. (PsycINFO Database Record PMID:26844648

  17. Preparation of Secondary-School History Teachers. Third Edition Revised.

    ERIC Educational Resources Information Center

    Cole, Donald B.; Pressly, Thomas

    This document is addressed to individuals concerned with the preparation of history teachers at the secondary-school level. The role of history is to provide a critical approach to the past, not simply to store and transmit the data society wants remembered. In order to produce effective teachers, a program of preparation depends, in part, upon…

  18. Student Papers in Local History.

    ERIC Educational Resources Information Center

    Johnson County Community Coll., Overland Park, KS. Johnson County Center for Local History.

    Thirteen papers on Kansas and Johnson County, Kansas history are presented. The papers were written by students in a course at the Johnson County Center for Local History or for independent study in local history. The papers are: "Conditions and Construction of Gardner Lake"; "The History of St. Joseph's Church, Shawnee, Kansas"; "Patrons of…

  19. Power Histories for Fuel Codes

    SciTech Connect

    Gilbert, E. R.; Rausch, W. N.; Panisko, F. E.

    1982-01-01

    Computations of power history effects on the pre-loss-of-coolant accident (LOCA) conditions of generic pressurized water reactor (PWR) and boiling water reactor (BWR) fuel rods were performed at Pacific Northwest Laboratory using the U.S. Nuclear Regulatory Commission (NRC) code FRAPCON-2. Comparisons were made between cases where the fuel operated at a high ( 11 LOCA-limited") power throughout life (20,000 MWd/MTU) and those where the fuel was at a lower power for most of its burnup and ramped to the high power at 10,000 or 20,000 MWd/MTU burnup. The PWR rod was calculated to have more cladding creepdown during the lower power cases, which resulted in slightly lower centerline temperatures (as much as 100{degrees}C). This result was insensitive to the method used to increase the power during the ramps (i.e., by increasing the average rod power or by changing the peak-to-average (P/A} ratio of the axial power shape). The calculations also indicate that the highest fuel centerline temperatures were reached at startup. The BWR rod, however, demonstrated a substantial dependence on the power history. In this case, the constant high-power rod released considerably more fission gas than the lower power cases (21% versus 0.4%), which resulted in temperature differences of up to 350°C. The hiqhest temperature was reached at end-of-life (EOL) in the constant high-power case.

  20. The History Education Project.

    ERIC Educational Resources Information Center

    Seifman, Eli

    In addition to briefly intoducing the History Education Project (HEP) sponsored by the American Historical Association and Indiana University, and funded by USOE, this report announces the establishment (Spring, 1970) of a regional HEP team at Stony Brook, describes its tentative plan of operation, and solicits assistance from the community. The…

  1. Making Invisible Histories Visible

    ERIC Educational Resources Information Center

    Hanssen, Ana Maria

    2012-01-01

    This article features Omaha Public Schools' "Making Invisible Histories Visible" program, or MIHV. Omaha's schools have a low failure rate among 8th graders but a high one among high school freshmen. MIHV was created to help at-risk students "adjust to the increased demands of high school." By working alongside teachers and mentors, the program's…

  2. A Little History (Invited)

    NASA Astrophysics Data System (ADS)

    Eagleson, P. S.

    2009-12-01

    Seeds of the Blue Book were planted in Cambridge, MA in the early 1960's, and variants thereof in Boulder, Colorado and Tucson, Arizona at a somewhat later date. However, flowering and cross-pollination did not occur until 1984 with the fruit ripening in 1991. We will briefly review this obscure history, search for lessons learned, and ponder what comes next.

  3. The History Computerization Project.

    ERIC Educational Resources Information Center

    Clark, David L.

    1992-01-01

    Description of the History Computerization Project, which is being developed for the exchange of information between researchers, librarians, archivists, museum curators, preservation groups, and historical societies, focuses on workshops that teach the use of computer database management for historical cataloging and research. (LRW)

  4. Observing Children Learning History.

    ERIC Educational Resources Information Center

    Blake, David W.

    1981-01-01

    Compares the suitability of two kinds of history curricula for the varying levels of cognitive development of 9- to 11-year-olds. Fifteen British students studied the Victorian Era using transcripts of original documents, while 15 classmates used standard textbooks. The documents seemed to give students greater awareness of the evidence sources.…

  5. Social Studies: Local History.

    ERIC Educational Resources Information Center

    Kressler, Joe, Comp.

    Elementary and secondary school teachers interested in developing a local history unit can adapt this fourth grade program created for three school districts in Cortland County, New York. Material is divided into 13 chapters. Chapter 1 charts the New York fourth grade curriculum by concept and content and outlines specific community study…

  6. A Biospheric Natural History.

    ERIC Educational Resources Information Center

    Thomashow, Mitchell

    2001-01-01

    A group of Maine birdwatchers recognizes that the presence or absence of migrating songbirds is related to complex biospheric patterns. For schoolchildren, community groups, and environmental scientists, such local natural history observations can be a pathway to perceiving and understanding global ecological change and then to developing…

  7. History of vaccination

    PubMed Central

    Plotkin, Stanley

    2014-01-01

    Vaccines have a history that started late in the 18th century. From the late 19th century, vaccines could be developed in the laboratory. However, in the 20th century, it became possible to develop vaccines based on immunologic markers. In the 21st century, molecular biology permits vaccine development that was not possible before. PMID:25136134

  8. Understanding World Economic History

    ERIC Educational Resources Information Center

    Whaples, Robert

    2013-01-01

    One joy of studying history is discovering people living meaningful lives and behaving in unusual ways that are startling to the modern reader--young or old. Why did pre-modern people living hundreds or even thousands of years ago do things so differently than we do? Robert Whaples states that Economic historians conclude that the key difference…

  9. Gill's 'History' restored

    NASA Astrophysics Data System (ADS)

    Hurn, Mark

    2009-06-01

    Note about the restoration of the copy of Sir David Gill's 'A History and Description of the Royal Observatory, Cape of Good Hope' in the Library of the Institute of Astronomy, Cambridge. The book was restored with funds provided by the SHA in thanks for facilities for meetings provided to the Institute.

  10. A History of Multimedia.

    ERIC Educational Resources Information Center

    Burke, Larry Kenneth

    The history of multimedia and descriptions of various multimedia events from 1900 to 1972 are presented. The development of multimedia events is described for four eras and four main classifications of events: multiscreen presentations, electronic media and performers, environmental theater, and environments. Five appendixes include a discussion…

  11. Ancient Egypt: History 380.

    ERIC Educational Resources Information Center

    Turk, Laraine D.

    "Ancient Egypt," an upper-division, non-required history course covering Egypt from pre-dynastic time through the Roman domination is described. General descriptive information is presented first, including the method of grading, expectation of student success rate, long-range course objectives, procedures for revising the course, major course…

  12. Narrative History and Theory

    ERIC Educational Resources Information Center

    Tamura, Eileen H.

    2011-01-01

    While narrative history has been the prevailing mode in historical scholarship, its preeminence has not gone unquestioned. In the 1980s, the role of narrative in historical writing was "the subject of extraordinarily intense debate." The historical backdrop of this debate can be traced to the preceding two decades, when four groups of thinkers…

  13. What Is World History?

    ERIC Educational Resources Information Center

    Thornton, Stephen J.

    2011-01-01

    In the United States, survey courses in world history have been staples of school programs for almost a century. But no consensus has emerged on the exact goals toward which these courses should be directed. Nor is there agreement on what topics to include or in what order topics should be studied. This article introduces some of the reasons for…

  14. A History of Psychology.

    ERIC Educational Resources Information Center

    Brown, Evan L.

    Any study of the history of psychology must first determine what is to be considered psychology, whether to stick to the relatively continuous Western tradition or to include others (e.g., Eastern, Oriental), and whether to investigate the impact of the socio-cultural events of the time on the views of that period or consider those views in a…

  15. Teaching Local History.

    ERIC Educational Resources Information Center

    Singer, Alan, Ed.

    2003-01-01

    This Social Science Docket theme issue focuses on teaching local history and included theme and non-themed articles, lesson plans, learning activities, and book, movie, and museum reviews designed for K-12 social studies teachers. Articles and materials in this issue are: "Editing Is Not Censorship" (Alan Singer); "Teachers Respond to 'Editing Is…

  16. Picturing Iowa's History.

    ERIC Educational Resources Information Center

    Ruth, Amy, Ed.

    1994-01-01

    This issue focuses on how advancements in photography affected Iowans and the pictures they took of their communities. Five famous and not so famous photographers who have taken pictures of Iowa's history are featured: (1) John Plumbe, Jr.; (2) Isaac A. Wetherby; (3) D. C. Hale; (4) Duluth Pieper; and (5) E. M. Clark. Instructions for making…

  17. History at NASA

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The efforts of the National Aeronautics and Space Administration to capture and record the events of the past are described, particularly the research accomplishments of NASA's agency-wide history program. A concise guide to the historical research resources available at NASA Headquarters in Washington, D.C., at NASA facilities around the country, and through the federal records systems is given.

  18. Mathematics in History.

    ERIC Educational Resources Information Center

    Hallenberg, Harvey

    1995-01-01

    Presents ideas for creating mathematical classroom activities associated with the history of mathematics: calculating sums and products the way ancient Greeks did it, using an abacus or moving stones on a sanded floor, and engaging elementary students through role playing specific mathematicians. Suggests that through such techniques, mathematics…

  19. Reconstructing Community History

    ERIC Educational Resources Information Center

    Shields, Amy

    2004-01-01

    History is alive and well in Lebanon, Missouri. Students in this small town in the southwest region of the state went above and beyond the community's expectations on this special project. This article describes this historical journey which began when students in a summer mural class reconstructed a mural that was originally created by a…

  20. History of Vietnamese Literature.

    ERIC Educational Resources Information Center

    Duong Quang Ham

    This is the first of a two-volume textbook, covering the official program of the Ministry of Education, of the secondary curriculum for the history of Vietnamese literature. It is divided into three main sections. The first section "First Year of the Secondary Cycle (Grade 11)" deals with (1) popular literature; (2) the influence of China, (3)…

  1. Why Military History?

    ERIC Educational Resources Information Center

    Bunting, Josiah, III

    2008-01-01

    Interest in military history is as strong as it has ever been--except on American college campuses. Lt. Gen. Josiah Bunting III examines why today's undergraduates need to study the facts of war, and why knowing its causes and consequences remain a vital part of our common knowledge.

  2. In a Word, History

    ERIC Educational Resources Information Center

    Dohan, Mary Helen

    1977-01-01

    Understanding words like "bionics" will open the mind to the horizons of another time when words like "railroad" evoked wonder and "to fly to the moon" was a metaphor for the impossible dream. Suggests that history teachers and English teachers should join together in using words to teach both subjects. (Editor/RK)

  3. Yearbooks as History Books.

    ERIC Educational Resources Information Center

    Kennedy, Jack

    1996-01-01

    Provides an eight-step plan to help yearbook production staffs research the history of their school and integrate it into the present, allowing students to see the "big picture" of how their school has affected and continues to affect the community in which they reside. (PA)

  4. History of Chemistry.

    ERIC Educational Resources Information Center

    Servos, John W.

    1985-01-01

    Discusses the development of chemistry in the United States by considering: (1) chemistry as an evolving body of ideas/techniques, and as a set of conceptual resources affecting and affected by the development of other sciences; and (2) chemistry related to the history of American social and economic institutions and practices. (JN)

  5. History of Biology.

    ERIC Educational Resources Information Center

    Maienschein, Jane

    1985-01-01

    Examines the history of biology in the United States by considering: (1) general trends about the nature of American biology; (2) sources of information; (3) biographies; (4) biological institutions; and (5) disciplinary studies. Indicates that the field is dominated by internalists who focus on particular persons and topics. (JN)

  6. Black History Month.

    ERIC Educational Resources Information Center

    Web Feet K-8, 2000

    2000-01-01

    This annotated subject guide to Web sites and additional resources focuses on Black History month. Specifies age levels for resources that include Web sites, CD-ROMs and software, videos, books, audios, magazines; includes professional resources; and presents a relevant class activity. (LRW)

  7. The Holocaust and History.

    ERIC Educational Resources Information Center

    Singer, Alan, Ed.

    2003-01-01

    This theme based journal issue consists of articles and teaching ideas focusing on the Holocaust and history. This publication contains the following materials: (1) "Multiple Perspectives on the Holocaust?" (Alan Singer); (2) "Responses to 'Multiple Perspectives on the Holocaust'"; (3) "Escape to Cuba: Story of Laura Kahn, a Holocaust Survivor"…

  8. A History of Resilience.

    ERIC Educational Resources Information Center

    Woodroof, Robert H.

    1990-01-01

    Reviews the history of private liberal arts junior colleges, from the founding of Lasell Female Academy in 1851, to their zenith in the mid-1940s, and their decline in numbers and enrollments in the 1970s. Emphasizes their role in the development of egalitarianism within U.S. higher education. (DMM)

  9. Indian Law Enforcement History.

    ERIC Educational Resources Information Center

    Etheridge, David

    Written as a tribute to American Indian law enforcement officers and the Indian Criminal Justice System, this monographh details the history of the legislative, judicial, financial, and cultural problems associated with the development of Indian law enforcement. Citing numerous court cases, pieces of legislation, and individual and organizational…

  10. Ownership and Object History

    ERIC Educational Resources Information Center

    Friedman, Ori; Neary, Karen R.; Defeyter, Margaret A.; Malcolm, Sarah L.

    2011-01-01

    Appropriate behavior in relation to an object often requires judging whether it is owned and, if so, by whom. The authors propose accounts of how people make these judgments. Our central claim is that both judgments often involve making inferences about object history. In judging whether objects are owned, people may assume that artifacts (e.g.,…

  11. Life History and Identity

    ERIC Educational Resources Information Center

    Tierney, William G.

    2013-01-01

    This article uses the life history method to chronicle the challenges of a low-income, first-generation student en route to college. The paper addresses three questions: how Manuel navigates college and related topics such as roommates, family, and money; how he creates social networks; and how he works with adults such as teachers and…

  12. Student Grade History System.

    ERIC Educational Resources Information Center

    White, Stephen R.

    This document describes the computerized procedures developed and utilized by Montgomery College (Maryland) to maintain records related to student academic progress. The new system was fully operable by fall 1972. Systems development included: (1) the conversion of past student records to a permanent grade history file; (2) the development of a…

  13. What Is Art History?

    ERIC Educational Resources Information Center

    Collins, Bradford R.

    1991-01-01

    Defines art history by examining visual and contextual information and distinguishes between the fine and applied arts. Discusses scientific neutrality and the personal and social uses of art. Concludes that it is impossible for art historians to be truly objective, but this should not be problematic because art historians interpret art works for…

  14. History and Civility

    ERIC Educational Resources Information Center

    Schaefer, Larry

    2015-01-01

    Larry Schaefer's history of civility is a succinct summary of the implicit and evolving definitions of civility over 2500 years of civilization. Beginning with the Romans and the root word "civitas," meaning the rights and duties of citizenship, civility appears in classical literature as integral to the roots of democracy in the context…

  15. History in Present Tense.

    ERIC Educational Resources Information Center

    Zakrewsky, Jackie

    1994-01-01

    Eschewing Little Mermaid and Ninja Turtle costumes, students at a Washington Montessori school celebrate Halloween dressed as John Adams, Clara Barton, and other historical figures. U.S. Department of Education recently recognized eight schools for using interdisciplinary approaches, devoting adequate instructional time to history, and addressing…

  16. Brazilian History through Journalism.

    ERIC Educational Resources Information Center

    Zaher, Celia Ribeiro; Varella, Maria Angelica

    This paper provides an overview of the beginnings of the newspaper in Brazil with information on the more significant titles and their role in the history of journalism and their impact on social change that occurred between the Imperial and Republican periods. Current collections at the National Library and legal deposit are discussed. It…

  17. Redefining American Literary History.

    ERIC Educational Resources Information Center

    Ruoff, A. LaVonne Brown, Ed.; Ward, Jerry W., Jr., Ed.

    This book is a collection of essays which provide starting points for a redefinition of American literary history based on a multiethnic and multiracial, rather than European, theory of culture. After an introduction by the editors, essays in the book are: "The Literatures of America: A Comparative Discipline" (Paul Lauter); "Defining the Canon"…

  18. Music in Iowa History.

    ERIC Educational Resources Information Center

    Frese, Millie K., Ed.

    1999-01-01

    This theme issue of "The Goldfinch" focuses on music as an art using sound in time to express ideas and emotions and contains articles featuring appreciations of some of Iowa's renowned musical artists. The first article gives an overview of music in Iowa's history. The next article describes Antonin Dvorak's summer sojourn in Spillville where he…

  19. Black History Speech

    ERIC Educational Resources Information Center

    Noldon, Carl

    2007-01-01

    The author argues in this speech that one cannot expect students in the school system to know and understand the genius of Black history if the curriculum is Eurocentric, which is a residue of racism. He states that his comments are designed for the enlightenment of those who suffer from a school system that "hypocritically manipulates Black…

  20. One Hong Kong, Two Histories: "History" and "Chinese History" in the Hong Kong School Curriculum.

    ERIC Educational Resources Information Center

    Kan, Flora; Vickers, Edward

    2002-01-01

    The history curriculum in Hong Kong schools is unique in having separate subjects--history and Chinese history--with distinct content, pedagogy, and assumptions about the discipline of history. In contrast to conventional theories of colonial education, this may have been a mutually convenient collaboration between the government and local…

  1. Using Histories to Implement Atomic Objects

    NASA Technical Reports Server (NTRS)

    Ng, Pui

    1987-01-01

    In this paper we describe an approach of implementing atomicity. Atomicity requires that computations appear to be all-or-nothing and executed in a serialization order. The approach we describe has three characteristics. First, it utilizes the semantics of an application to improve concurrency. Second, it reduces the complexity of application-dependent synchronization code by analyzing the process of writing it. In fact, the process can be automated with logic programming. Third, our approach hides the protocol used to arrive at a serialization order from the applications. As a result, different protocols can be used without affecting the applications. Our approach uses a history tree abstraction. The history tree captures the ordering relationship among concurrent computations. By determining what types of computations exist in the history tree and their parameters, a computation can determine whether it can proceed.

  2. [Affective dependency].

    PubMed

    Scantamburlo, G; Pitchot, W; Ansseau, M

    2013-01-01

    Affective dependency is characterized by emotional distress (insecure attachment) and dependency to another person with a low self-esteem and reassurance need. The paper proposes a reflection on the definition of emotional dependency and the confusion caused by various denominations. Overprotective and authoritarian parenting, cultural and socio-environmental factors may contribute to the development of dependent personality. Psychological epigenetic factors, such as early socio-emotional trauma could on neuronal circuits in prefronto-limbic regions that are essential for emotional behaviour.We also focus on the interrelations between dependent personality, domestic violence and addictions. The objective for the clinician is to propose a restoration of self-esteem and therapeutic strategies focused on autonomy. PMID:23888587

  3. Sequence History Update Tool

    NASA Technical Reports Server (NTRS)

    Khanampompan, Teerapat; Gladden, Roy; Fisher, Forest; DelGuercio, Chris

    2008-01-01

    The Sequence History Update Tool performs Web-based sequence statistics archiving for Mars Reconnaissance Orbiter (MRO). Using a single UNIX command, the software takes advantage of sequencing conventions to automatically extract the needed statistics from multiple files. This information is then used to populate a PHP database, which is then seamlessly formatted into a dynamic Web page. This tool replaces a previous tedious and error-prone process of manually editing HTML code to construct a Web-based table. Because the tool manages all of the statistics gathering and file delivery to and from multiple data sources spread across multiple servers, there is also a considerable time and effort savings. With the use of The Sequence History Update Tool what previously took minutes is now done in less than 30 seconds, and now provides a more accurate archival record of the sequence commanding for MRO.

  4. History of Oriental Astronomy

    NASA Astrophysics Data System (ADS)

    Ansari, S. M. Razaullah

    2002-12-01

    This volume deals specifically with recent original research in the history of Chinese, Korean, Japanese, Islamic, and Indian astronomy. It strikes a balance between landmarks of history of Ancient and Medieval Astronomy in the Orient on one hand, and on the other the transmission of the European Astronomy into the countries of the Orient. Most contributions are based on research by the experts in this field. The book also indicates the status of astronomy research in non-European cultural areas of the world. The book is especially of interest to historians of astronomy and science, and students of cultural heritage. Link: http://www.wkap.nl/prod/b/1-4020-0657-8

  5. History of interleukin-4.

    PubMed

    Paul, William E

    2015-09-01

    The history of the discovery and the development of our knowledge of IL-4 exemplifies the path of progress in biomedical science. There are unanticipated twists and turns although progress is made, sometimes quickly, other times far too slowly. Illustrative is the extended time from the first report of IL-4 in 1982 to the establishment of the efficacy of blocking IL-4 and its congener IL-13 in the treatment of moderate to severe asthma and atopic dermatitis, a period of 31years. The author was "present at the creation" and has been a participant or a witness to virtually all the major advances and recounts here his recollection of this history. PMID:25814340

  6. History of Korean Neurosurgery.

    PubMed

    Hwang, Sung-nam

    2015-08-01

    The year 2012 was the 50th anniversary of the Korean Neurosurgical Society, and in 2013, the 15th World Congress of Neurosurgery took place in Seoul, Korea. Thus, it is an appropriate occasion to introduce the world to the history of the Korean Neurosurgical Society and the foundation, development, and growth of Korean neurosurgery. Historical materials and pictures were collected and reviewed from the history book and photo albums of the Korean Neurosurgical Society. During the last 50 years, the Korean Neurosurgical Society and Korean neurosurgery have developed and grown enormously not only in quantity but also in quality. In every aspect, the turning point from the old to the new era of the Korean Neurosurgical Society and Korean neurosurgery was the year 1980. PMID:25064423

  7. Brief History of Syphilis

    PubMed Central

    Tampa, M; Sarbu, I; Matei, C; Benea, V; Georgescu, SR

    2014-01-01

    Abstract Before the discovery of Treponema pallidum as the etiologic agent, the origins of syphilis have been the subject of several debates. Diverse therapeutic agents were employed in an attempt to cure the disease. Examining the milestones in the history of syphilis, the present article reviews the existing theories that tried to explain the origins of the disease, the approach in art, the cultural and the evolution of the treatments from the empiric means to the discovery of penicillin. PMID:24653750

  8. A passion for history

    NASA Astrophysics Data System (ADS)

    Marshall, Robin

    2008-02-01

    While walking through the recently refurbished physics department at Manchester University with its newly painted walls and gleaming windows, a sense of history is never far behind. Many famous physicists have worked and studied at the university, including Ernest Rutherford, J J Thomson, William Bragg and James Chadwick. Indeed, when Albert Einstein came to the UK in 1921, it was at Manchester that he gave his first lecture to a British audience.

  9. [History of sun protection].

    PubMed

    Couteau, Céline; Coiffard, Laurence

    2010-07-01

    Human behavior towards the sun has changed over the years along with trends. Tan succeeded the white complexion. The sunscreens appeared recently in history. It is lining up with the discovery of bad effects due to prolonged exposure to ultraviolet at the end of the 19th century. Initially, those products had no signs of efficacy on their packaging, then the solar protection factors increased gradually, up to a limit value of 50+ more recently. PMID:21032925

  10. Life history evolution: successes, limitations, and prospects.

    PubMed

    Stearns, S C

    2000-11-01

    Life history theory tries to explain how evolution designs organisms to achieve reproductive success. The design is a solution to an ecological problem posed by the environment and subject to constraints intrinsic to the organism. Work on life histories has expanded the role of phenotypes in evolutionary theory, extending the range of predictions from genetic patterns to whole-organism traits directly connected to fitness. Among the questions answered are the following: Why are organisms small or large? Why do they mature early or late? Why do they have few or many offspring? Why do they have a short or a long life? Why must they grow old and die? The classical approach to life histories was optimization; it has had some convincing empirical success. Recently non-equilibrium approaches involving frequency-dependence, density-dependence, evolutionary game theory, adaptive dynamics, and explicit population dynamics have supplanted optimization as the preferred approach. They have not yet had as much empirical success, but there are logical reasons to prefer them, and they may soon extend the impact of life history theory into population dynamics and interspecific interactions in coevolving communities. PMID:11151666