9,798 research outputs found

    Patterns of Late Cenozoic exhumation deduced from apatite and zircon U-He ages from Fiordland, New Zealand

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    New apatite and zircon (U-Th)/He ages from the Fiordland region of New Zealand's South Island expand on earlier results and provide new constraints on patterns of Late Cenozoic exhumation and cooling across this region. Zircon (U-Th)/He cooling ages, in combination with increased density of apatite ages, show that in addition to a gradual northward decrease in cooling ages that was seen during an earlier phase of this study, there is also a trend toward younger cooling ages to the east. Distinct breaks in cooling age patterns on southwestern Fiordland appear to be correlated to the location of previously mapped faults. The northward decrease in ages may reflect asynchronous cooling related to migration in the locus of exhumation driven by subduction initiation, or it may reflect synchronous regional exhumation that exposed different structural levels across Fiordland, or some combination of these effects. In either case, differential exhumation accommodated by major and minor faults that dissect Fiordland basement rocks apparently played an important role in producing the resulting age patterns

    Thiodithiazyl compounds

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    Instrumental leadership: Measurement and extension of transformational-transactional leadership theory.

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    Leaders must scan the internal and external environment, chart strategic and task objectives, and provide performance feedback. These instrumental leadership (IL) functions go beyond the motivational and quid-pro quo leader behaviors that comprise the full-range-transformational, transactional, and laissez faire-leadership model. In four studies we examined the construct validity of IL. We found evidence for a four-factor IL model that was highly prototypical of good leadership. IL predicted top-level leader emergence controlling for the full-range factors, initiating structure, and consideration. It also explained unique variance in outcomes beyond the full-range factors; the effects of transformational leadership were vastly overstated when IL was omitted from the model. We discuss the importance of a "fuller full-range" leadership theory for theory and practice. We also showcase our methodological contributions regarding corrections for common method variance (i.e., endogeneity) bias using two-stage least squares (2SLS) regression and Monte Carlo split-sample designs

    Insights from unifying modern approximations to infections on networks

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    Networks are increasingly central to modern science owing to their ability to conceptualize multiple interacting components of a complex system. As a specific example of this, understanding the implications of contact network structure for the transmission of infectious diseases remains a key issue in epidemiology. Three broad approaches to this problem exist: explicit simulation; derivation of exact results for special networks; and dynamical approximations. This paper focuses on the last of these approaches, and makes two main contributions. Firstly, formal mathematical links are demonstrated between several prima facie unrelated dynamical approximations. And secondly, these links are used to derive two novel dynamical models for network epidemiology, which are compared against explicit stochastic simulation. The success of these new models provides improved understanding about the interaction of network structure and transmission dynamics

    Social encounter networks : collective properties and disease transmission

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    A fundamental challenge of modern infectious disease epidemiology is to quantify the networks of social and physical contacts through which transmission can occur. Understanding the collective properties of these interactions is critical for both accurate prediction of the spread of infection and determining optimal control measures. However, even the basic properties of such networks are poorly quantified, forcing predictions to be made based on strong assumptions concerning network structure. Here, we report on the results of a large-scale survey of social encounters mainly conducted in Great Britain. First, we characterize the distribution of contacts, which possesses a lognormal body and a power-law tail with an exponent of −2.45; we provide a plausible mechanistic model that captures this form. Analysis of the high level of local clustering of contacts reveals additional structure within the network, implying that social contacts are degree assortative. Finally, we describe the epidemiological implications of this local network structure: these contradict the usual predictions from networks with heavy-tailed degree distributions and contain public-health messages about control. Our findings help us to determine the types of realistic network structure that should be assumed in future population level studies of infection transmission, leading to better interpretations of epidemiological data and more appropriate policy decisions

    The synthesis of 15 mu infrared horizon radiance profiles from meteorological data inputs

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    Computational computer program for modeling infrared horizon radiance profile using pressure and temperature profile input

    New assessment focuses on ecosystems, human well-being, and the climate system

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    Multi-Scaling of Correlation Functions in Single Species Reaction-Diffusion Systems

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    We derive the multi-fractal scaling of probability distributions of multi-particle configurations for the binary reaction-diffusion system A+AA+A \to \emptyset in d2d \leq 2 and for the ternary system 3A3A \to \emptyset in d=1d=1. For the binary reaction we find that the probability Pt(N,ΔV)P_{t}(N, \Delta V) of finding NN particles in a fixed volume element ΔV\Delta V at time tt decays in the limit of large time as (lntt)N(lnt)N(N1)2(\frac{\ln t}{t})^{N}(\ln t)^{-\frac{N(N-1)}{2}} for d=2d=2 and t^{-Nd/2}t^{-\frac{N(N-1)\epsilon}{4}+\mathcal{O}(\ep^2)} for d<2d<2. Here \ep=2-d. For the ternary reaction in one dimension we find that Pt(N,ΔV)(lntt)N/2(lnt)N(N1)(N2)6P_{t}(N,\Delta V) \sim (\frac{\ln t}{t})^{N/2}(\ln t)^{-\frac{N(N-1)(N-2)}{6}}. The principal tool of our study is the dynamical renormalization group. We compare predictions of \ep-expansions for Pt(N,ΔV)P_{t}(N,\Delta V) for binary reaction in one dimension against exact known results. We conclude that the \ep-corrections of order two and higher are absent in the above answer for Pt(N,ΔV)P_{t}(N, \Delta V) for N=1,2,3,4N=1,2,3,4. Furthermore we conjecture the absence of \ep^2-corrections for all values of NN.Comment: 10 pages, 6 figure
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