1,056 research outputs found

    The management of twin pregnancy

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    Increasing crop richness and reducing field sizes provide higher yields to pollinator-dependent crops

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    Agricultural landscapes cover >60% of terrestrial landscapes. While biodiversity conservation and crop productivity have been seen as mutually exclusive options for a long time, recent research suggests that agricultural landscapes represent significant opportunities for biodiversity conservation outside of traditional protected areas. Here, we use a unique dataset that includes annual monitoring of 12,300 permanent 25-ha plots over two decades across Spain to assess how agricultural landscapes are changing over time. We focus particularly on landscape composition and configuration variables such as the diversity of crops grown within a landscape, average plot size or the cover of natural habitats and assess how changes to these variables affect the ability of agricultural landscapes to ensure high yields. We find potential synergistic strategies that are good for biodiversity conservation and can also lead to increasing crop yields. Specifically, we find that management practices that favour increasing biodiversity values such as maintaining small field sizes and high crop richness values at the landscape scale actually led to the greatest average yield values across 54 crops, 41% of which depend on pollinator activity for reproduction. Policy implications: While our analysis does not factor in economic costs and benefits, we show that synergy scenarios that are good for biodiversity conservation and crop productivity are possible, yet not as widespread as they could be. © 2022 The Authors. Journal of Applied Ecology © 2022 British Ecological Society.We thank Sergio Mancheño Losa from the Spanish Ministerio de Agricultura, Pesca y Ali‐mentación for his support in providing the data used in this paper and to all the staff members that made ESYRCE database possible. A.M. received funding from an Ikerbasque, Basque Foundation for Science Research Fellowship. Research was also supported by the Spanish State Research Agency through Maria de Maeztu Excellence Unit accreditation (MDM‐2017‐0714) and the Basque Government BERC Programme. We appreciate funding from BiodivERsA joint call for research proposals (under the BiodivScen ERA‐Net COFUND programme and with the funding organizations AEI, NWO, ECCyT and NSF)

    The generalized Robinson-Foulds metric

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    The Robinson-Foulds (RF) metric is arguably the most widely used measure of phylogenetic tree similarity, despite its well-known shortcomings: For example, moving a single taxon in a tree can result in a tree that has maximum distance to the original one; but the two trees are identical if we remove the single taxon. To this end, we propose a natural extension of the RF metric that does not simply count identical clades but instead, also takes similar clades into consideration. In contrast to previous approaches, our model requires the matching between clades to respect the structure of the two trees, a property that the classical RF metric exhibits, too. We show that computing this generalized RF metric is, unfortunately, NP-hard. We then present a simple Integer Linear Program for its computation, and evaluate it by an all-against-all comparison of 100 trees from a benchmark data set. We find that matchings that respect the tree structure differ significantly from those that do not, underlining the importance of this natural condition.Comment: Peer-reviewed and presented as part of the 13th Workshop on Algorithms in Bioinformatics (WABI2013

    Phonon Hall effect in ionic crystals in the presence of static magnetic field

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    We study phonon Hall effect (PHE) for ionic crystals in the presence of static magnetic field. Using Green-Kubo formula, we present an exact calculation of thermal conductivity tensor by considering both positive and negative frequency phonons. Numerical results are shown for some lattices such as hexagonal lattices, triangular lattices, and square lattices. We find that the PHE occurs on the nonmagnetic ionic crystal NaCl, although the magnitude is very small which is due to the tiny charge-to-mass ratio of the ions. The off-diagonal thermal conductivity is finite for nonzero magnetic field and changes sign for high value of magnetic field at high temperature. We also found that the off-diagonal thermal conductivity diverges as ±1/T\pm{1/T} at low temperature

    A Fuzzy Spatio-Temporal-based Approach for Activity Recognition

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    International audienceOver the last decade, there has been a significant deployment of systems dedicated to surveillance. These systems make use of real-time sensors that generate continuous streams of data. Despite their success in many cases, the increased number of sensors leads to a cognitive overload for the operator in charge of their analysis. However, the context and the application requires an ability to react in real-time. The research presented in this paper introduces a spatio-temporal-based approach the objective of which is to provide a qualitative interpretation of the behavior of an entity (e.g., a human or vehicle). The process is formally supported by a fuzzy logic-based approach, and designed in order to be as generic as possible

    Oscillations During Inflation and the Cosmological Density Perturbations

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    Adiabatic (curvature) perturbations are produced during a period of cosmological inflation that is driven by a single scalar field, the inflaton. On particle physics grounds -- though -- it is natural to expect that this scalar field is coupled to other scalar degrees of freedom. This gives rise to oscillations between the perturbation of the inflaton field and the perturbations of the other scalar degrees of freedom, similar to the phenomenon of neutrino oscillations. Since the degree of the mixing is governed by the squared mass matrix of the scalar fields, the oscillations can occur even if the energy density of the extra scalar fields is much smaller than the energy density of the inflaton field. The probability of oscillation is resonantly amplified when perturbations cross the horizon and the perturbations in the inflaton field may disappear at horizon crossing giving rise to perturbations in scalar fields other than the inflaton. Adiabatic and isocurvature perturbations are inevitably correlated at the end of inflation and we provide a simple expression for the cross-correlation in terms of the slow-roll parameters.Comment: 23 pages, uses LaTeX, added few reference

    Boost Invariance and Multiplicity Dependence of the Charge Balance Functionin π+p\pi^{+}p and K+pK^{+}p Collisions at s=22\sqrt s= 22 GeV/c

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    Boost invariance and multiplicity dependence of the charge balance function are studied in \pi^{+}\rp and \rK^{+}\rp collisions at 250 GeV/cc incident beam momentum. Charge balance, as well as charge fluctuations, are found to be boost invariant over the whole rapidity region, but both depend on the size of the rapidity window. It is also found that the balance function becomes narrower with increasing multiplicity, consistent with the narrowing of the balance function when centrality and/or system size increase, as observed in current relativistic heavy ion experiments.Comment: 4 pages, 5 figures, Revte

    Noise parametric identification and whitening for LIGO 40-meter interferometer data

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    We report the analysis we made on data taken by Caltech 40-meter prototype interferometer to identify the noise power spectral density and to whiten the sequence of noise. We concentrate our study on data taken in November 1994, in particular we analyzed two frames of data: the 18nov94.2.frame and the 19nov94.2.frame. We show that it is possible to whiten these data, to a good degree of whiteness, using a high order whitening filter. Moreover we can choose to whiten only restricted band of frequencies around the region we are interested in, obtaining a higher level of whiteness.Comment: 11 pages, 15 figures, accepted for publication by Physical Review
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