5,888 research outputs found

    Reptile assemblages across agricultural landscapes: where does biodiversity hide?

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    Comunidades de reptiles en paisajes agrícolas: ¿dónde se esconde la biodiversidad?La transición de la agricultura tradicional a la intensiva, orientada a la producción a gran escala, ha alterado rápidamente los paisajes agrícolas, lo que ha conllevado la reducción y fragmentación de los hábitats naturales y la consiguiente pérdida de biodiversidad. La herpetofauna está gravemente amenazada por la intensificación agrícola en todo el mundo, pero se sabe poco acerca de su distribución en los ecosistemas agrícolas, especialmente a escala local. Se analizaron la abundancia y la diversidad de reptiles en ocho usos del suelo agrícolas y seminaturales, así como dentro de parches de vegetación intercalados entre cultivos. Curiosamente, la mayoría de los reptiles se observó en los parches de vegetación, mientras que en los cultivos intensivos y los pastos solo se encontró una especie de lagarto. La riqueza de individuos y de especies aumenta cuando los parches de vegetación están en contacto con zonas seminaturales, independientemente de la anchura y la estructura de la vegetación de estas. En vista de los resultados obtenidos, que ponen de relieve la influencia de las características del paisaje de menor importancia en la presencia de vertebrados en los ecosistemas agrícolas intensivos, recomendamos incluir parches de vegetación como medida de conservación de los vertebrados en los paisajes agrícolas.The transition from traditional to intensive farming, aimed at large–scale production, has rapidly altered agricultural landscapes, leading to the reduction and fragmentation of natural habitats and to the consequent loss of biodiversity. Herpetofauna is seriously threatened by agriculture intensification worldwide, but less is known about its distribution in agro–ecosystems, especially at field scale. We analysed reptile abundance and diversity in eight agricultural and semi–natural land uses, and inside vegetated buffer strips interspersed among fields. Interestingly, most reptiles were recorded in the buffer strips while intensive crops and pastures hosted just one lizard species. Richness of individuals and species increased when strips were connected to semi–natural areas, independently of their width and vegetation structure. In view of our results, that highlight the role of minor landscape features for the presence of vertebrates in intensive agro–ecosystems, we recommend the implementation of buffer strips among the measures for vertebrate conservation in agricultural landscapes.Comunidades de reptiles en paisajes agrícolas: ¿dónde se esconde la biodiversidad?La transición de la agricultura tradicional a la intensiva, orientada a la producción a gran escala, ha alterado rápidamente los paisajes agrícolas, lo que ha conllevado la reducción y fragmentación de los hábitats naturales y la consiguiente pérdida de biodiversidad. La herpetofauna está gravemente amenazada por la intensificación agrícola en todo el mundo, pero se sabe poco acerca de su distribución en los ecosistemas agrícolas, especialmente a escala local. Se analizaron la abundancia y la diversidad de reptiles en ocho usos del suelo agrícolas y seminaturales, así como dentro de parches de vegetación intercalados entre cultivos. Curiosamente, la mayoría de los reptiles se observó en los parches de vegetación, mientras que en los cultivos intensivos y los pastos solo se encontró una especie de lagarto. La riqueza de individuos y de especies aumenta cuando los parches de vegetación están en contacto con zonas seminaturales, independientemente de la anchura y la estructura de la vegetación de estas. En vista de los resultados obtenidos, que ponen de relieve la influencia de las características del paisaje de menor importancia en la presencia de vertebrados en los ecosistemas agrícolas intensivos, recomendamos incluir parches de vegetación como medida de conservación de los vertebrados en los paisajes agrícolas

    Experimental determination of the frequency and field dependence of Specific Loss Power in Magnetic Fluid Hyperthermia

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    Magnetic nanoparticles are promising systems for biomedical applications and in particular for Magnetic Fluid Hyperthermia, a promising therapy that utilizes the heat released by such systems to damage tumor cells. We present an experimental study of the physical properties that influences the capability of heat release, i.e. the Specific Loss Power, SLP, of three biocompatible ferrofluid samples having a magnetic core of maghemite with different core diameter d= 10.2, 14.6 and 19.7 nm. The SLP was measured as a function of frequency f and intensity of the applied alternating magnetic field H, and it turned out to depend on the core diameter, as expected. The results allowed us to highlight experimentally that the physical mechanism responsible for the heating is size-dependent and to establish, at applied constant frequency, the phenomenological functional relationship SLP=cH^x, with 2<x<3 for all samples. The x-value depends on sample size and field frequency/ intensity, here chosen in the typical range of operating magnetic hyperthermia devices. For the smallest sample, the effective relaxation time Teff=19.5 ns obtained from SLP data is in agreement with the value estimated from magnetization data, thus confirming the validity of the Linear Response Theory model for this system at properly chosen field intensity and frequency

    Near-infrared spectroscopy study of tourniquet-induced forearm ischaemia in patients with coronary artery disease

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    Near-Infrared Spectroscopy (NIR) can be employed to monitor local changes in haemodynamics and oxygenation of human tissues. A preliminary study has been performed in order to evaluate the NIRS transmittance response to induced forearm ischaemia in patients with coronary artery disease (CAD). The population consists in 40 patients with cardiovascular risk factors and angiographically documented CAD, compared to a group of 13 normal subjects. By inflating and subsequently deflating a cuff placed around the patient arm, an ischaemia has been induced and released, and the patients have been observed until recovery of the basal conditions. A custom LAIRS spectrometer (IRIS) has been used to collect the backscattered light intensities from the patient forearm throughout the ischaemic and the recovery phase. The time dependence of the near-infrared transmittance on the control group is consistent with the available literature. On the contrary, the magnitude and dynamics of the NIRS signal on the CAD patients show deviations from the documented normal behavior, which can be tentatively attributed to abnormal vessel stiffness. These preliminary results, while validating the performance of the IRIS spectrometer, are strongly conducive towards the applicability of the NIRS technique to ischaemia analysis and to endothelial dysfunction characterization in CAD patients with cardiovascular risk factors.Publisher PD

    Photometric and spectroscopic variations of the Be star HD 112999

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    Be objects are stars of B spectral type showing lines of the Balmer series in emission. The presence of these lines is attributed to the existence of an extended envelope, disk type, around them. Some stars are observed in both the Be and normal B-type spectroscopic states and they are known as transient Be stars. In this paper we show the analysis carried out on a new possible transient Be star, labelled HD 112999, using spectroscopic optical observations and photometric data.Comment: 10 pages, 5 figures, accepted for publication in IBV

    BIG GEO DATA MANAGEMENT: AN EXPLORATION WITH SOCIAL MEDIA AND TELECOMMUNICATIONS OPEN DATA

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    The term Big Data has been recently used to define big, highly varied, complex data sets, which are created and updated at a high speed and require faster processing, namely, a reduced time to filter and analyse relevant data. These data is also increasingly becoming Open Data (data that can be freely distributed) made public by the government, agencies, private enterprises and among others. There are at least two issues that can obstruct the availability and use of Open Big Datasets: Firstly, the gathering and geoprocessing of these datasets are very computationally intensive; hence, it is necessary to integrate high-performance solutions, preferably internet based, to achieve the goals. Secondly, the problems of heterogeneity and inconsistency in geospatial data are well known and affect the data integration process, but is particularly problematic for Big Geo Data. Therefore, Big Geo Data integration will be one of the most challenging issues to solve. With these applications, we demonstrate that is possible to provide processed Big Geo Data to common users, using open geospatial standards and technologies. NoSQL databases like MongoDB and frameworks like RASDAMAN could offer different functionalities that facilitate working with larger volumes and more heterogeneous geospatial data sources

    Measurements and tests on FBK silicon sensors with an optimized electronic design for a CTA camera

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    In October 2013, the Italian Ministry approved the funding of a Research & Development (R&D) study, within the "Progetto Premiale TElescopi CHErenkov made in Italy (TECHE)", devoted to the development of a demonstrator for a camera for the Cherenkov Telescope Array (CTA) consortium. The demonstrator consists of a sensor plane based on the Silicon Photomultiplier (SiPM) technology and on an electronics designed for signal sampling. Preliminary tests on a matrix of sensors produced by the Fondazione Bruno Kessler (FBK-Trento, Italy) and on electronic prototypes produced by SITAEL S.p.A. will be presented. In particular, we used different designs of the electronics in order to optimize the output signals in terms of tail cancellation. This is crucial for applications where a high background is expected, as for the CTA experiment.Comment: 5 pages, 6 figures; Proceedings of the 10th Workshop on Science with the New Generation of High-Energy Gamma-ray experiments (SciNeGHE) - PoS(Scineghe2014)00

    The embedded clusters DBS 77, 78, 102, and 160-161 and their link with the interstellar medium

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    Aims. We report a study of the global properties of some embedded clusters placed in the fourth quadrant of the Milky Way to clarify some issues related with their location into the Galaxy and their stellar formation processes. Methods. We performed BVI photometric observations in the region of DBS 77, 78, 102, 160, and 161 clusters and infrared spectroscopy in DBS 77 region. They were complemented with JHK data from VVV survey combined with 2MASS catalogue, and used mid-infrared information from GLIMPSE catalogue. We also searched for HI data from SGPS and PMN radio surveys, and previous spectroscopic stellar classification. The spectroscopic and photometric information allowed us to estimate the spectral classification of the brightest stars of each studied region. On the other hand, we used the radio data to investigate the interstellar material parameters and the continuum sources probably associated with the respective stellar components. Results. We estimated the basic physical parameters of the clusters (reddening, distance, age, and initial mass function). We searched for HII regions located near to the studied clusters and we analyzed the possible link between them. In the particular case of DBS 160-161 clusters, we identified the HI bubble B332.5-0.1-42 located around them. We found that the mechanical energy injected to the interstellar medium by the more massive stars of this couple of clusters was enough to generate the bubble.Comment: 15 pages, 14 figures, 6 tables, accepted for publication in A&
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