3,661 research outputs found

    Breeding Guilds Determine Frog Response to Edge Effects in Brazil’s Atlantic Forest

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    Understanding the response of species with differing life-history traits to habitat edges and habitat conversion helps predict their likelihood of persistence across changing landscape. In Brazil’s Atlantic Forest, we evaluated frog richness and abundance by breeding guild at four distances from the edge of a reserve: i) 200 m inside the forest, ii) 50 m inside the forest, iii) at the forest edge, and iv) 50 m inside three different converted habitats (coffee plantation, non-native Eucalyptus plantation, and abandoned pastures, hereafter matrix types). By sampling a dry and a wet season, we recorded 622 individual frogs representing 29 species, of which three were undescribed. Breeding guild (i.e. bromeliad, leaf-litter, and water-body breeders) was the most important variable explaining frog distributions in relation to edge effects and matrix types. Leaf-litter and bromeliad breeders decreased in richness and abundance from the forest interior toward the matrix habitats. Water-body breeders increased in richness toward the matrix and remained relatively stable in abundance across distances. Number of large trees (i.e. DBH \u3e 15 cm) and bromeliads best explained frog richness and abundance across distances. Twenty species found in the interior of the forest were not found in any matrix habitat. Richness and abundance across breeding guilds were higher in the rainy season but frog distributions were similar across the four distances in the two seasons. Across matrix types, leaf-litter species primarily used Eucalyptus plantations, whereas water-body species primarily used coffee plantations. Bromeliad breeders were not found inside any matrix habitat. Our study highlights the importance of primary forest for bromeliad and leaf-litter breeders. We propose that water-body breeders use edge and matrix habitats to reach breeding habitats along the valleys. Including life-history characteristics, such as breeding guild, can improve predictions of frog distributions in response to edge effect and matrix types, and can guide more effective management and conservation actions

    Behavioral Intervention Components Associated With Cost-effectiveness: A Comparison of Six Domains.

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    BACKGROUND: To help implement behavior change interventions (BCIs) it is important to be able to characterize their key components and determine their effectiveness. PURPOSE: This study assessed and compared the components of BCIs in terms of intervention functions identified using the Behaviour Change Wheel Framework (BCW) and in terms of their specific behavior change techniques (BCTs) identified using the BCT TaxonomyV1, across six behavioral domains and the association of these with cost-effectiveness. METHODS: BCIs in 251 studies targeting smoking, diet, exercise, sexual health, alcohol and multiple health behaviors, were specified in terms of their intervention functions and their BCTs, grouped into 16 categories. Associations with cost-effectiveness measured in terms of incremental cost-effectiveness ratio (ICER) upper and lower estimates were determined using regression analysis. RESULTS: The most prevalent functions were increasing knowledge through education (72.1%) and imparting skills through training (74.9%). The most prevalent BCT groupings were shaping knowledge (86.5%), changing behavioral antecedents (53.0%), supporting self-regulation (47.7%), and providing social support (44.6%). Intervention functions associated with better cost-effectiveness were those based on training (βlow = -15044.3; p = .002), persuasion (βlow = -19384.9; p = .001; βupp = -25947.6; p < .001) and restriction (βupp = -32286.1; p = .019), and with lower cost-effectiveness were those based on environmental restructuring (β = 15023.9low; p = .033). BCT groupings associated with better cost-effectiveness were goals and planning (βlow = -8537.3; p = .019 and βupp = -12416.9; p = .037) and comparison of behavior (βlow = -13561.9, p = .047 and βupp = -30650.2; p = .006). Those associated with lower cost-effectiveness were natural consequences (βlow = 7729.4; p = .033) and reward and threat (βlow = 20106.7; p = .004). CONCLUSIONS: BCIs that focused on training, persuasion and restriction may be more cost-effective, as may those that encourage goal setting and comparison of behaviors with others

    Ares I Stage Separation System Design Certification Testing

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    NASA is committed to the development of a new crew launch vehicle, the Ares I, that can support human missions to low Earth orbit (LEO) and the moon with unprecedented safety and reliability. NASA's Constellation program comprises the Ares I and Ares V launch vehicles, the Orion crew vehicle, and the Altair lunar lander. Based on historical precedent, stage separation is one of the most significant technical and systems engineering challenges that must be addressed in order to achieve this commitment. This paper surveys historical separation system tests that have been completed in order to ensure staging of other launch vehicles. Key separation system design trades evaluated for Ares I include single vs. dual separation plane options, retro-rockets vs. pneumatic gas actuators, small solid motor quantity/placement/timing, and continuous vs. clamshell interstage configuration options. Both subscale and full-scale tests are required to address the prediction of complex dynamic loading scenarios present during staging events. Test objectives such as separation system functionality, and pyroshock and debris field measurements for the full-scale tests are described. Discussion about the test article, support infrastructure and instrumentation are provided

    New Experimental limit on Optical Photon Coupling to Neutral, Scalar Bosons

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    We report on the first results of a sensitive search for scalar coupling of photons to a light neutral boson in the mass range of approximately 1.0 milli-electron volts and coupling strength greater than 10−6^-6 GeV−1^-1 using optical photons. This was a photon regeneration experiment using the "light shining through a wall" technique in which laser light was passed through a strong magnetic field upstream of an optical beam dump; regenerated laser light was then searched for downstream of a second magnetic field region optically shielded from the former. Our results show no evidence for scalar coupling in this region of parameter space.Comment: pdf-file, 10 pages, 4 figures, submitted to Physical Review Letter

    Duality, thermodynamics, and the linear programming problem in constraint-based models of metabolism

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    It is shown that the dual to the linear programming problem that arises in constraint-based models of metabolism can be given a thermodynamic interpretation in which the shadow prices are chemical potential analogues, and the objective is to minimise free energy consumption given a free energy drain corresponding to growth. The interpretation is distinct from conventional non-equilibrium thermodynamics, although it does satisfy a minimum entropy production principle. It can be used to motivate extensions of constraint-based modelling, for example to microbial ecosystems.Comment: 4 pages, 2 figures, 1 table, RevTeX 4, final accepted versio

    Kosterlitz-Thouless Universality in a Fermionic System

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    A new extension of the attractive Hubbard model is constructed to study the critical behavior near a finite temperature superconducting phase transition in two dimensions using the recently developed meron-cluster algorithm. Unlike previous calculations in the attractive Hubbard model which were limited to small lattices, the new algorithm is used to study the critical behavior on lattices as large as 128×128128\times 128. These precise results for the first time show that a fermionic system can undergo a finite temperature phase transition whose critical behavior is well described by the predictions of Kosterlitz and Thouless almost three decades ago. In particular it is confirmed that the spatial winding number susceptibility obeys the well known predictions of finite size scaling for T<TcT<T_c and up to logarithmic corrections the pair susceptibility scales as L2−ηL^{2-\eta} at large volumes with 0≤η≤0.250\leq\eta\leq 0.25 for 0≤T≤Tc0\leq T\leq T_c.Comment: Revtex format; 4 pages, 2 figure

    Behaviour Change Update: Stage 1. BCT analysis of existing, cost-effective interventions

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    Seventy-nine cost-effective interventions across six different health behaviours (smoking cessation, diet, physical activity, alcohol, sexual health, multiple behaviour targets) were identified from 23 economic reports. Interventions were mainly of high intensity, set in primary care or the community, delivered by health professionals and aimed at individuals from the general population, involving pharmacological or other forms of support. Education, enablement, training and persuasion were the focus of the majority of interventions, clustering around BCTs concerning: shaping knowledge; goals and planning; social support; antecedents and natural consequences of behaviour; outcome comparison; and feedback and monitoring. Interventions included an average of ten BCTs with ‘instructions on how to perform a behaviour’, ‘unspecified social support’, ‘information about health consequences’ and ‘problem solving’ included in 81%, 67%, 57% and 53% of interventions, respectively. While the use of ‘choice architecture’ was common, being present in 71% of cost-effective interventions, prevalence was lower (29%) when stricter criteria to define ‘choice architecture’ were applied. Sexual health interventions were least cost-effective but no other characteristics or BCTs were related to cost-effectiveness estimates. However, these findings need to be interpreted cautiously given 1.) the limitations imposed by considering only cost-effective interventions in this report, 2.) the reliance on often incomplete information in published papers (possibly not accurately reflecting intervention content) and 3.) the lack of consensus for a definition of ‘choice architecture’

    Evidence for equilibrium iron isotope fractionation by nitrate-reducing iron(II)-oxidizing bacteria

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    Iron isotope fractionations produced during chemical and biological Fe(II) oxidation are sensitive to the proportions and nature of dissolved and solid-phase Fe species present, as well as the extent of isotopic exchange between precipitates and aqueous Fe. Iron isotopes therefore potentially constrain the mechanisms and pathways of Fe redox transformations in modern and ancient environments. In the present study, we followed in batch experiments Fe isotope fractionations between Fe(II)_(aq) and Fe(III) oxide/hydroxide precipitates produced by the Fe(III) mineral encrusting, nitrate-reducing, Fe(II)-oxidizing Acidovorax sp. strain BoFeN1. Isotopic fractionation in ^(56)Fe/^(54)Fe approached that expected for equilibrium conditions, assuming an equilibrium Δ^(56)Fe_(Fe(OH)3–Fe(II)aq) fractionation factor of +3.0‰. Previous studies have shown that Fe(II) oxidation by this Acidovorax strain occurs in the periplasm, and we propose that Fe isotope equilibrium is maintained through redox cycling via coupled electron and atom exchange between Fe(II)_(aq) and Fe(III) precipitates in the contained environment of the periplasm. In addition to the apparent equilibrium isotopic fractionation, these experiments also record the kinetic effects of initial rapid oxidation, and possible phase transformations of the Fe(III) precipitates. Attainment of Fe isotope equilibrium between Fe(III) oxide/hydroxide precipitates and Fe(II)_(aq) by neutrophilic, Fe(II)-oxidizing bacteria or through abiologic Fe(II)_(aq) oxidation is generally not expected or observed, because the poor solubility of their metabolic product, i.e. Fe(III), usually leads to rapid precipitation of Fe(III) minerals, and hence expression of a kinetic fractionation upon precipitation; in the absence of redox cycling between Fe(II)_(aq) and precipitate, kinetic isotope fractionations are likely to be retained. These results highlight the distinct Fe isotope fractionations that are produced by different pathways of biological and abiological Fe(II) oxidation

    The Physical Origins of Entropy Production, Free Energy Dissipation and their Mathematical Representations

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    A complete mathematical theory of nonequilibrium thermodynamics of stochastic systems in terms of master equations is presented. As generalizations of isothermal entropy and free energy, two functions of states play central roles: the Gibbs entropy SS and the relative entropy FF, which are related via the stationary distribution of the stochastic dynamics. SS satisfies the fundamental entropy balance equation dS/dt=ep−hd/TdS/dt=e_p-h_d/T with entropy production rate ep≥0e_p\ge 0 and heat dissipation rate hdh_d, while dF/dt=−fd≤0dF/dt=-f_d\le 0. For closed systems that satisfy detailed balance: Tep(t)=fd(t)Te_p(t)=f_d(t). For open system one has Tep(t)=fd(t)+Qhk(t)Te_p(t)=f_d(t)+Q_{hk}(t) where the housekeeping heat Qhk≥0Q_{hk}\ge 0 was first introduced in the phenomenological nonequilibrium steady state thermodynamics. Entropy production epe_p consists of free energy dissipation associated with spontaneous relaxation, fdf_d, and active energy pumping that sustains the open system QhkQ_{hk}. The amount of excess heat involved in the relaxation Qex=hd−Qhk=fd−T(dS/dt)Q_{ex}=h_d-Q_{hk} = f_d-T(dS/dt).Comment: 4 pages, no figure
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