7,038 research outputs found

    Leveraging limited data from wildlife monitoring in a conflict affected region in Venezuela

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    Efficient monitoring of biodiversity-rich areas in conflict-affected areas with poor rule of law requires a combination of different analytical approaches to account for data biases and incompleteness. In the upland Amazon region of Venezuela, in Canaima National Park, we initiated biodiversity monitoring in 2015, but it was interrupted by the establishment of a large-scale mining development plan in 2016, compromising the temporal and geographical extent of monitoring and the security of researchers. We used a resource selection function model framework that considers imperfect detectability and supplemented detections from camera trap surveys with opportunistic off-camera records (including animal tracks and direct sighting) to (1) gain insight into the value of additional occurrence records to accurately predict wildlife resource use in the perturbated area (deforestation, fire, swidden agriculture, and human settlements vicinity), (2) when faced with security and budget constraints. Our approach maximized the use of available data and accounted for biases and data gaps. Adding data from poorly sampled areas had mixed results on estimates of resource use for restricted species, but improved predictions for widespread species. If budget or resources are limited, we recommend focusing on one location with both on-camera and off-camera records over two with cameras. Combining camera trap records with other field observations (28 mammals and 16 birds) allowed us to understand responses of 17 species to deforestation, 15 to fire, and 13 to swidden agriculture. Our study encourages the use of combinations of methods to support conservation in high-biodiversity sites, where access is restricted, researchers are vulnerable, and unequal sampling efforts exist

    Desarrollo de un prototipo de sistema de riego automatizado para zonas urbanas de la ciudad de Cuenca

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    Nuestro proyecto está conformado por varias estructuras tanto en el hardware como una electroválvula, un soporte, motor paso a paso, etc. y su software efectuado con Visual Basic y Arduino, esto con el objetivo de crear un sistema de riego ya sea a escala pequeña para un jardín en el patio de una casa hasta zonas extensas que conforman los regadíos de maizales, áreas verdes de colegios, etc. El prototipo de sistema de riego automatizado se realizó por ser práctico para las personas, dando comodidad en el hogar puesto que no se tendría que hacer un mayor esfuerzo por salir y regar sus plantas ya que lo harían mediante una aplicación. La idea surge a partir de la observación de cultivos y plantas marchitadas por falta de agua, esto normalmente se da por la falta de tiempo que se tiene en el día a día o por no recordar la presencia de las plantas. Como se especificó en el punto uno, nos hemos enfocado en zonas domésticas, es decir, a escalas pequeñas como jardines, áreas de trabajo, de oficina, etc. La funcionalidad se basa en poder regar plantas en un determinado tiempo, en nuestro caso hemos incluido la función de escoger cuanta cantidad de agua se desea regar. La cantidad de agua se relaciona con la cantidad de tiempo que se mantiene abierta la electroválvula

    Droplet impact onto moving liquids

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    From rain drops landing on the ocean to inkjet printing, the impact of droplets onto moving liquid surfaces is a ubiquitous process in nature and in industry. A rich range of phenomena can arise. The behaviour depends on the inertia, the properties of the drops and the relative speeds in the impact zone. While the result ranges from tranquil coalescence to violent splashing, intermediate regimes also occur, including partial and complete bouncing and even 'surfing' of the droplet. These regimes are determined by the ratio of the drop and surface velocities and the liquid properties. A regime diagram can be constructed in which distinct dynamical regimes are clearly identified.This project was supported by the EPSRC (grant EP/H018913/1), the John Fell Oxford University Press Research Fund, and the Royal Society (through a University Research Fellowship and a Research Grant)

    On the fraction of dark matter in charged massive particles (CHAMPs)

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    From various cosmological, astrophysical and terrestrial requirements, we derive conservative upper bounds on the present-day fraction of the mass of the Galactic dark matter (DM) halo in charged massive particles (CHAMPs). If dark matter particles are neutral but decay lately into CHAMPs, the lack of detection of heavy hydrogen in sea water and the vertical pressure equilibrium in the Galactic disc turn out to put the most stringent bounds. Adopting very conservative assumptions about the recoiling velocity of CHAMPs in the decay and on the decay energy deposited in baryonic gas, we find that the lifetime for decaying neutral DM must be > (0.9-3.4)x 10^3 Gyr. Even assuming the gyroradii of CHAMPs in the Galactic magnetic field are too small for halo CHAMPs to reach Earth, the present-day fraction of the mass of the Galactic halo in CHAMPs should be < (0.4-1.4)x 10^{-2}. We show that redistributing the DM through the coupling between CHAMPs and the ubiquitous magnetic fields cannot be a solution to the cuspy halo problem in dwarf galaxies.Comment: 21 pages, 2 figures. To appear in JCA

    Rethinking Causality: Thomas Aquinas\u27 Argument From Motion & the Kalām Cosmological Argument

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    Ever since they were formulated in the Middle Ages, St. Thomas Aquinas\u27 famous Five Ways to demonstrate the existence of God have been frequently debated. During this process there have been several misconceptions of what Aquinas actually meant, especially when discussing his cosmological arguments. While previous researchers have managed to tease out why Aquinas accepts some infinite regresses and rejects others, I attempt to add on to this by demonstrating the centrality of his metaphysics in his argument from motion. Aquinas cannot be properly understood or debated with a contemporary view of causality, but rather must wrestle with the concepts he actually employs in the arguments. To demonstrate this, I will compare the Thomistic argument from motion to the contemporary Kalām cosmological argument of William Lane Craig. Although some may consider it beneficial to base theistic arguments on more modern principles, this analysis shows that the metaphysical framework used by Aquinas is much less vulnerable to the rebuttals that otherwise challenge the Kalām argument, and that their differences in strength rest on their differences in metaphysics

    Improved Iterative Coordinated Beamforming Based on Singular Value Decomposition for Multiuser Mimo Systems With Limited Feedforward

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    Coordinated beamforming based on singular value decomposition is an iterative method to jointly optimize thetransmit beamformers and receive combiners, to achieve high levels of sum rates in the downlink of multiusersystems, by exploiting the multi-dimensional wireless channel created by multiple transmit and receive antennas. The optimization is done at the base station and the quantized beamformers are sent to the users through a low rate link.In this work, we propose to optimize this algorithm by reducing the number of iterations and improving its uncoded bit error rate performance. Simulation results show that our proposal achieves a better bit error rate with a lower number of iterations than the original algorithm

    Spectra of weighted algebras of holomorphic functions

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    We consider weighted algebras of holomorphic functions on a Banach space. We determine conditions on a family of weights that assure that the corresponding weighted space is an algebra or has polynomial Schauder decompositions. We study the spectra of weighted algebras and endow them with an analytic structure. We also deal with composition operators and algebra homomorphisms, in particular to investigate how their induced mappings act on the analytic structure of the spectrum. Moreover, a Banach-Stone type question is addressed.Comment: 25 pages Corrected typo

    Orbital-scale climate forcing of grassland burning in southern Africa.

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    This is the final version of the article. Available from the publisher via the DOI in this record.Although grassland and savanna occupy only a quarter of the world's vegetation, burning in these ecosystems accounts for roughly half the global carbon emissions from fire. However, the processes that govern changes in grassland burning are poorly understood, particularly on time scales beyond satellite records. We analyzed microcharcoal, sediments, and geochemistry in a high-resolution marine sediment core off Namibia to identify the processes that have controlled biomass burning in southern African grassland ecosystems under large, multimillennial-scale climate changes. Six fire cycles occurred during the past 170,000 y in southern Africa that correspond both in timing and magnitude to the precessional forcing of north-south shifts in the Intertropical Convergence Zone. Contrary to the conventional expectation that fire increases with higher temperatures and increased drought, we found that wetter and cooler climates cause increased burning in the study region, owing to a shift in rainfall amount and seasonality (and thus vegetation flammability). We also show that charcoal morphology (i.e., the particle's length-to-width ratio) can be used to reconstruct changes in fire activity as well as biome shifts over time. Our results provide essential context for understanding current and future grassland-fire dynamics and their associated carbon emissions.We thank Linda Rossignol for picking the foraminifera for carbon radiometric dating, Olivier Ther for XRF analysis, Marie-Hélène Castera and Muriel Georget for laboratory assistance, V. Hanquiez for extracting bathymetric data, Thibault Caley for providing the East African monsoon regression model data, Lydie Dupont for sharing the pollen data of cores GeoB1711 and MD96-2048, and Louis Scott for providing Wonderkrater’s charcoal data. This research was funded by European Research Council Advanced Grant TRACSYMBOLS 249587. The postdoctoral position of A.-L.D was funded by this project
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