2,903 research outputs found
The Impact of User Effects on the Performance of Dual Receive Antenna Diversity Systems in Flat Rayleigh Fading Channels
In this paper we study the impact of user effects on the performance of receive antenna diversity systems in flat Rayleigh fading channels. Three diversity combining techniques are compared: maximal ratio combining (MRC), equal gain combining (EGC), and selection combining (SC). User effects are considered in two scenarios: 1) body loss (the reduction of effective antenna gain due to user effects) on a single antenna, and 2) equal body loss on both antennas. The system performance is assessed in terms of mean SNR, link reliability, bit error rate of BPSK, diversity order and ergodic capacity. Our results show that body loss on a single antenna has limited (bounded) impact on system performance. In comparison, body loss on both antennas has unlimited (unbounded) impact and can severely degrade system performance. Our results also show that with increasing body loss on a single antenna the performance of EGC drops faster than that of MRC and SC. When body loss on a single antenna is larger than a certain level, EGC is not a “sub-optimal” method anymore and has worse performance than SC
Distribution and conservation of Oncilla (Leopardus tigrinus) of Yungas, Argentina
En la Argentina y las Yungas, el Tirica es el felino con rango de distribución más restringido y probablemente localmente raro. En este trabajo se presenta un mapa de prioridades de conservación para el Tirica (Leopardus tigrinus) que se desarrolló en base a un mapa de distribución potencial y un mapa de uso de la tierra. Para al mapa de distribución se desarrolló un modelo de distribución de la especie usando el programa MaxEnt y 64 puntos de presencia actual de la Argentina (Yungas y Bosque Atlántico). Se midió el rendimiento general del mapa con el AUC o área bajo la curva ROC, que fue de 0.996; lo que indica un buen rendimiento. Se superpuso este mapa con un mapa de uso de la tierra humano para excluir áreas no aptas para la especie. El mapa resultante indica que ya se ha perdido casi la mitad (48%) del hábitat potencial para la especie, en particular en el borde oriental de su distribución y en el sur donde probablemente la especie nunca estuvo presente. Dos aras son importantes para la conectividad del hábitat y por la alta probabilidad de presencia y por lo tanto, para la conservación de Tirica. Se espera que este mapa sea de utilidad para conservacionistas y tomadores de decisiones.In Argentina and Yungas, Oncilla is the felid species with the smallest distribution range and probably locally rare. Based on the potential distribution map and human land use we present a map indicating important areas for Oncilla conservation. Therefore we developed a potential distribution map for Oncilla (Leopardus tigrinus) using MaxEnt and 64 existing presence points of Argentina (Yungas and Atlantic Forest). We measured the general performance of the map using the AUC or area under the Roc curve, which was 0.996, indicating a model with a good general performance. We superimposed this map with a map of human land use to exclude areas not suitable for the species. The resulting map indicates that already almost half (48%) of potential habitat for the species is lost, particularly in the eastern limit of its distribution and in the south, where the species probably was never present. Two areas are important for habitat connectivity or high presence probability and therefore, conservation of Oncilla. This map is hopefully useful for conservation actions and decision makers.Fil: Cuyckens, Griet An Erica. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias. Centro de Estudios Ambientales Territoriales y Sociales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Perovic, P. G.. Administracion de Parques Nacionales; Argentin
Living on the edge: regional distribution and retracting range of the jaguar (Panthera onca)
Vivir al límite: distribución regional y superficie ocupada por el jaguar en retroceso (Panthera onca) Para conservar la biodiversidad, es necesario entender cómo se distribuyen las especies y qué variables ambientales determinan dicha distribución. Los cambios inducidos por el hombre en la ocupación del suelo y la pérdida de hábitat ponen en peligro a numerosas especies de todo el mundo, especialmente a grandes carnívoros. Diferenciar la influencia del clima y la de los usos del suelo en la distribución de jaguar (Panthera onca) es importante para su conservación. Esta especie, que tradicionalmente se distribuía desde los Estados Unidos hasta el sur de Argentina, ha visto reducida su distribución a escala regional y local. En este trabajo predecimos el rango de distribución de la especie utilizando registros de presencia histórica, variables climáticas y algoritmos predictivos obtenidos con MaxEnt. Nos centramos especialmente en su límite más austral en Argentina para indicar los límites históricos de esta especie y describir el nicho que ocupa actualmente en estas poblaciones marginales. Para estimar el efecto de las acciones antrópicas, utilizamos una capa de ocupación del suelo para limitar la distribución del jaguar. Recopilamos una buena cantidad de registros de presencia en todo el área de distribución histórica de la especie y estimamos una distribución regional histórica desde la Patagonia hasta los –50° de latitud. Nuestros resultados ponen de manifiesto que el área de distribución del jaguar se está contrayendo de forma alarmante en el límite meridional y también en el septentrional, y que los cambios de ocupación y de uso del suelo son una amenaza para la especie. Tras restar del nicho estudiado la ocupación del suelo que no es adecuada, descubrimos que la superficie idónea para el jaguar desde el punto de vista ambiental en la zona del estudio se ha reducido hasta el 5,2% de su tamaño original. Por consiguiente, advertimos del elevado riesgo de extinción que acecha al jaguar en Argentina.Vivir al límite: distribución regional y superficie ocupada por el jaguar en retroceso (Panthera onca) Para conservar la biodiversidad, es necesario entender cómo se distribuyen las especies y qué variables ambientales determinan dicha distribución. Los cambios inducidos por el hombre en la ocupación del suelo y la pérdida de hábitat ponen en peligro a numerosas especies de todo el mundo, especialmente a grandes carnívoros. Diferenciar la influencia del clima y la de los usos del suelo en la distribución de jaguar (Panthera onca) es importante para su conservación. Esta especie, que tradicionalmente se distribuía desde los Estados Unidos hasta el sur de Argentina, ha visto reducida su distribución a escala regional y local. En este trabajo predecimos el rango de distribución de la especie utilizando registros de presencia histórica, variables climáticas y algoritmos predictivos obtenidos con MaxEnt. Nos centramos especialmente en su límite más austral en Argentina para indicar los límites históricos de esta especie y describir el nicho que ocupa actualmente en estas poblaciones marginales. Para estimar el efecto de las acciones antrópicas, utilizamos una capa de ocupación del suelo para limitar la distribución del jaguar. Recopilamos una buena cantidad de registros de presencia en todo el área de distribución histórica de la especie y estimamos una distribución regional histórica desde la Patagonia hasta los –50° de latitud. Nuestros resultados ponen de manifiesto que el área de distribución del jaguar se está contrayendo de forma alarmante en el límite meridional y también en el septentrional, y que los cambios de ocupación y de uso del suelo son una amenaza para la especie. Tras restar del nicho estudiado la ocupación del suelo que no es adecuada, descubrimos que la superficie idónea para el jaguar desde el punto de vista ambiental en la zona del estudio se ha reducido hasta el 5,2% de su tamaño original. Por consiguiente, advertimos del elevado riesgo de extinción que acecha al jaguar en Argentina.To preserve biodiversity we need to understand how species are distributed and which aspects of the environment determine these distributions. Human–induced changes in land–cover and loss of habitat threaten many species, particularly large carnivores, in many parts of the world. Differentiating the influence of climate and human land use on the distribution of the jaguar (Panthera onca) is important for the species’ conservation. Historically distributed from the United States to southern Argentina, the jaguar has seen its distribution range decreased at regional and local scales. Here we predict the species’ distribution range using historical records of its presence, climate variables, and MaxEnt predictive algorithms. We focus especially on its southernmost limit in Argentina to indicate the historical limits of this species, and describe its present niche in these edge populations. To estimate the effect of human activity we used a raster of land cover to restrict the jaguar’s distribution. We collected a large amount of presence records through the species’ historical range, and estimated a historical regional distribution ranging from Patagonia up to latitude –50°S. Our findings show the range of the jaguar is decreasing severely in its southern limit and also in its northern limit, and that changes in land cover/use are threats to the species. After subtracting non–suitable land–cover from the studied niche, we found the environmentally suitable area for the jaguar in the study area has decreased to 5.2% of its original size. We thus warn of the high extinction risk of the jaguar in Argentina
The interface of syntax with pragmatics and prosody in children with Autism Spectrum Disorders
In order to study problems of individuals with Autism Spectrum Disorders (ASD) with morphosyntax, we investigated twenty high-functioning Greek-speaking children (mean age:6;11) and twenty age- and language-matched typically developing children on environments that allow or forbid object clitics or their corresponding noun phrase. Children with ASD fell behind typically developing in comprehending and producing simple clitics and producing noun phrases in focus structures. The two groups performed similarly in comprehending and producing clitics in clitic left dislocation and in producing noun phrases in non-focus structures. We argue that children with ASD have difficulties at the interface of(morpho)syntax with pragmatics and prosody, namely, distinguishing a discourse prominent element, and considering intonation relevant for a particular interpretation that excludes clitics
Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV
The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8 TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum
Integrated motor drives: state of the art and future trends
With increased need for high power density, high efficiency and high temperature capabilities in Aerospace and Automotive applications, Integrated Motor Drives (IMD) offers a potential solution. However, close physical integration of the converter and the machine may also lead to an increase in components temperature. This requires careful mechanical, structural and thermal analysis; and design of the IMD system.
This paper reviews existing IMD technologies and their thermal effects on the IMD system. The effects of the power electronics (PE) position on the IMD system and its respective thermal management concepts are also investigated. The challenges faced in designing and manufacturing of an IMD along with the mechanical and structural impacts of close physical integration is also discussed and potential solutions are provided. Potential converter topologies for an IMD like the Matrix converter, 2-level Bridge, 3-level NPC and Multiphase full bridge converters are also reviewed. Wide band gap devices like SiC and GaN and their packaging in power modules for IMDs are also discussed. Power modules components and packaging technologies are also presented
Characterization of conserved properties of hemagglutinin of H5N1 and human influenza viruses: possible consequences for therapy and infection control
<p>Abstract</p> <p>Background</p> <p>Epidemics caused by highly pathogenic avian influenza virus (HPAIV) are a continuing threat to human health and to the world's economy. The development of approaches, which help to understand the significance of structural changes resulting from the alarming mutational propensity for human-to-human transmission of HPAIV, is of particularly interest. Here we compare informational and structural properties of the hemagglutinin (HA) of H5N1 virus and human influenza virus subtypes, which are important for the receptor/virus interaction.</p> <p>Results</p> <p>Presented results revealed that HA proteins encode highly conserved information that differ between influenza virus subtypes H5N1, H1N1, H3N2, H7N7 and defined an HA domain which may modulate interaction with receptor. We also found that about one third of H5N1 viruses which are isolated during the 2006/07 influenza outbreak in Egypt possibly evolve towards receptor usage similar to that of seasonal H1N1.</p> <p>Conclusion</p> <p>The presented results may help to better understand the interaction of influenza virus with its receptor(s) and to identify new therapeutic targets for drug development.</p
Group B Streptococcus vaccine development: present status and future considerations, with emphasis on perspectives for low and middle income countries.
Globally, group B Streptococcus (GBS) remains the leading cause of sepsis and meningitis in young infants, with its greatest burden in the first 90 days of life. Intrapartum antibiotic prophylaxis (IAP) for women at risk of transmitting GBS to their newborns has been effective in reducing, but not eliminating, the young infant GBS disease burden in many high income countries. However, identification of women at risk and administration of IAP is very difficult in many low and middle income country (LMIC) settings, and is not possible for home deliveries. Immunization of pregnant women with a GBS vaccine represents an alternate pathway to protecting newborns from GBS disease, through the transplacental antibody transfer to the fetus in utero. This approach to prevent GBS disease in young infants is currently under development, and is approaching late stage clinical evaluation. This manuscript includes a review of the natural history of the disease, global disease burden estimates, diagnosis and existing control options in different settings, the biological rationale for a vaccine including previous supportive studies, analysis of current candidates in development, possible correlates of protection and current status of immunogenicity assays. Future potential vaccine development pathways to licensure and use in LMICs, trial design and implementation options are discussed, with the objective to provide a basis for reflection, rather than recommendations
Matrix-assisted laser desorption/ionization time of flight mass spectrometry identification of Vibrio (Listonella) anguillarum isolated from sea bass and sea bream
Vibrio (Listonella) anguillarum is a pathogenic bacterium causing septicaemia in a wide range of marine organisms and inducing severe mortalities, thus it is crucial to conduct its accurate and rapid identification. The aim of this study was to assess MALDI-TOF MS as a method of choice for identification of clinical V. anguillarum isolates from affected marine fish. Since the method accuracy might be influenced by the type of the medium used, as well as by the incubation conditions, we tested V. anguillarum isolates grown on standard media with and without the addition of NaCl, cultured at three incubation temperatures, and at three incubation periods. The best scores were retrieved for V. anguillarum strains grown on NaCl-supplemented tryptone soy agar (TSA) at 22°C and incubated for 48h (100% identification to species level; overall score 2.232), followed by incubation at 37°C and 48h (100% to species level; score 2.192). The strains grown on non-supplemented TSA gave the best readings when incubated at 22°C for 72h (100% identification to species level; overall score 2.182), followed by incubation at 15°C for 72h (100% to species level; score 2.160). Unreliable identifications and no-identifications were growing with the incubation duration at 37°C, on both media, amounting to 88.89% for 7d incubation on supplemented TSA, and 92.60% for 7d incubation on non-supplemented TSA. The age of the cultured strains and use of media significantly impacted the mass spectra, demonstrating that for reliable identification, MALDI-TOF MS protein fingerprinting with the on-target extraction should be performed on strains grown on a NaCl-supplemented medium at temperatures between 15 and 22°C, incubated for 48-72 hours
The DNA-PAINT palette: a comprehensive performance analysis of fluorescent dyes
DNA points accumulation for imaging in nanoscale topography (DNA-PAINT) is a super-resolution fluorescence microscopy technique that achieves single-molecule ‘blinking’ by transient DNA hybridization. Despite blinking kinetics being largely independent of fluorescent dye choice, the dye employed substantially affects measurement quality. Thus far, there has been no systematic overview of dye performance for DNA-PAINT. Here we defined four key parameters characterizing performance: brightness, signal-to-background ratio, DNA-PAINT docking site damage and off-target signal. We then analyzed 18 fluorescent dyes in three spectral regions and examined them both in DNA origami nanostructures, establishing a reference standard, and in a cellular environment, targeting the nuclear pore complex protein Nup96. Finally, having identified several well-performing dyes for each excitation wavelength, we conducted simultaneous three-color DNA-PAINT combined with Exchange-PAINT to image six protein targets in neurons at ~16 nm resolution in less than 2 h. We thus provide guidelines for DNA-PAINT dye selection and evaluation and an overview of performances of commonly used dyes
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