3,563 research outputs found

    The role of physiological traits in assortment among and within fish shoals

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    Individuals of gregarious species often group with conspecifics to which they are phenotypically similar. This among-group assortment has been studied for body size, sex and relatedness. However, the role of physiological traits has been largely overlooked. Here, we discuss mechanisms by which physiological traits—particularly those related to metabolism and locomotor performance—may result in phenotypic assortment not only among but also within animal groups. At the among-group level, varying combinations of passive assortment, active assortment, phenotypic plasticity and selective mortality may generate phenotypic differences among groups. Even within groups, however, individual variation in energy requirements, aerobic and anaerobic capacity, neurological lateralization and tolerance to environmental stressors are likely to produce differences in the spatial location of individuals or associations between group-mates with specific physiological phenotypes. Owing to the greater availability of empirical research, we focus on groups of fishes (i.e. shoals and schools). Increased knowledge of physiological mechanisms influencing among- and within-group assortment will enhance our understanding of fundamental concepts regarding optimal group size, predator avoidance, group cohesion, information transfer, life-history strategies and the evolutionary effects of group membership. In a broader perspective, predicting animal responses to environmental change will be impossible without a comprehensive understanding of the physiological basis of the formation and functioning of animal social groups. This article is part of the themed issue ‘Physiological determinants of social behaviour in animals’

    Measuring Lives Under Wait-and-See Versions of the Rule Against Perpetuities

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    Spinoza

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    "Spinoza", second edition. Encyclopedia entry for the Springer Encyclopedia of EM Phil and the Sciences, ed. D. Jalobeanu and C. T. Wolfe

    The V3, V4 and V6 bands of formaldehyde: A spectral catalog from 900 cm(-1) to 1580 cm(-1)

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    The results of a complete high resolution study of the three vibration-rotation bands v sub 3, v sub 4, and V sub 6 using both TDLs and FT-IR spectroscopy are presented. The reults are given in terms of a table of over 8000 predicted transition frequencies and strengths. A plot of the predicted and calculated spectra is shown. Over 3000 transitions were assigned and used in the simultaneous analysis of the three bands. The simultaneous fit permitted a rigorous study of Coriolis and other type iterations among bands yielding improved molecular constants. Line intensities of 28 transitions measured by a TDL and 20 transitions from FTS data were used, along with the eigenvectors from the frequency fitting, in a least squares analysis to evaluate the band strengths

    Revised List of Type Specimens on Deposit in the University of California Davis Nematode Collection

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    The list of deposited type specimens is updated for the University of California Davis Nematode Collection, as recommended by the International Code of Zoological Nomenclature. The type collection includes 1,001 species and more than 11,000 individual specimens mounted on microscope slides. This list can be used as a reference to locate specimens but is not meant to clarify ambiguities that may exist concerning the type status of particular specimens

    Violating conformal invariance: Two-dimensional clusters grafted to wedges, cones, and branch points of Riemann surfaces

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    We present simulations of 2-d site animals on square and triangular lattices in non-trivial geomeLattice animals are one of the few critical models in statistical mechanics violating conformal invariance. We present here simulations of 2-d site animals on square and triangular lattices in non-trivial geometries. The simulations are done with the newly developed PERM algorithm which gives very precise estimates of the partition sum, yielding precise values for the entropic exponent θ\theta (ZN∼μNN−θZ_N \sim \mu^N N^{-\theta}). In particular, we studied animals grafted to the tips of wedges with a wide range of angles α\alpha, to the tips of cones (wedges with the sides glued together), and to branching points of Riemann surfaces. The latter can either have kk sheets and no boundary, generalizing in this way cones to angles α>360\alpha > 360 degrees, or can have boundaries, generalizing wedges. We find conformal invariance behavior, θ∼1/α\theta \sim 1/\alpha, only for small angles (α≪2π\alpha \ll 2\pi), while θ≈const−α/2π\theta \approx const -\alpha/2\pi for α≫2π\alpha \gg 2\pi. These scalings hold both for wedges and cones. A heuristic (non-conformal) argument for the behavior at large α\alpha is given, and comparison is made with critical percolation.Comment: 4 pages, includes 3 figure

    Nothing good happens after dark: the influence of temporal factors on motor carrier crash severity

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    Motor carrier safety is a topic of great importance for both industry and makers of public policy. Regulatory agencies, such as the Federal Motor Carrier Safety Administration (FMCSA), regularly publish data detailing the circumstances surrounding roadway accidents. FMCSA’s Large Truck and Bus Crash Facts (LTBCF) data demonstrate an increase in accidents during daylight hours and on weekdays. Roadway risks are ever-present but differ by time of day and day of the week. These differences may potentially engender crashes of different severities at different times. This study analyzes FMCSA LTBCF data to determine when crashes of different severities are more likely to occur. Findings indicate that crashes resulting in property damage are more likely to occur during the day and on weekdays. However, fatal and injury crashes are significantly more likely during nights and weekends. Recommendations to improve safety outcomes are provided along with suggestions for future research

    Connecting up strategy: are senior strategy directors a missing link?

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    With companies being exhorted to become more strategically agile and internally connected, this article examines the role of the Senior Strategy Director, the executive tasked specifically with internal strategy. In particular, it explores what they do, what specific capabilities they deploy to enable effective contribution to the company, and in what ways they facilitate the connectedness of strategy. An analysis of multiple interviews over time with Senior Strategy Directors of large companies shows the vital and challenging role these executives play in both shaping, connecting up, and executing strategy. This article identifies the particular capabilities necessary for Senior Strategy Directors to perform their role and shows how it all depends upon their skilful deployment. These findings have significant implications for understanding unfolding micro-processes of strategy in large organizations, for assumptions about the skills and capabilities necessary to be an effective Senior Strategy Director, and for business schools in terms of the content and style of strategy courses they provide

    The social psychology of collective victimhood

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    Collective victimhood, which results from the experience of being targeted as members of a group, has powerful effects on individuals and groups. The focus of this Special Issue is on how people respond to collective victimhood and how these responses shape intergroup relations. We introduce the Special Issue with an overview of emerging social psychological research on collective victimhood. To date, this research has focused mostly on destructive versus positive consequences of collective victimhood for relations with an adversary group, and examined victim groups' needs, victim beliefs, and underlying social identity and categorization processes. We identify several neglected factors in this literature, some of which are addressed by the empirical contributions in the current issue. The Special Issue offers novel perspectives on collective victimhood, presenting findings based on a diverse range of methods with mostly community samples that have direct and vicarious experiences of collective harm in different countries

    Generalized Ensemble and Tempering Simulations: A Unified View

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    From the underlying Master equations we derive one-dimensional stochastic processes that describe generalized ensemble simulations as well as tempering (simulated and parallel) simulations. The representations obtained are either in the form of a one-dimensional Fokker-Planck equation or a hopping process on a one-dimensional chain. In particular, we discuss the conditions under which these representations are valid approximate Markovian descriptions of the random walk in order parameter or control parameter space. They allow a unified discussion of the stationary distribution on, as well as of the stationary flow across each space. We demonstrate that optimizing the flow is equivalent to minimizing the first passage time for crossing the space, and discuss the consequences of our results for optimizing simulations. Finally, we point out the limitations of these representations under conditions of broken ergodicity.Comment: 11 pages Latex, 2 eps figures, revised version, typos corrected, PRE in pres
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