3,353 research outputs found
Mapeamento das unidades de paisagem das sub-regiões da Nhecolândia e Poconé, Pantanal Mato-Grossense.
O mapeamento apresentado sintetiza as principais unidades de paisagens das sub-regiões da Nhecolândia e de Poconé, no Pantanal brasileiro. Os mapas baseiam-se na identificação de formações vegetais dominantes conforme o grau de inundação. Observou-se que a sub-região da Nhecolândia é dominada por formações savânicas sazonalmente inundáveis (41%) e a sub-região de Poconé é dominada por formações florestais sazonalmente inundáveis (26%). O domÃnio de florestas em Poconé deve-se principalmente ao domÃnio do cambará (Vochysia divergens). Ambas as sub-regiões apresentaram extensas áreas de savanas. As pastagens nativas de melhor qualidade estão localizadas nas áreas inundáveis, embora nessas áreas haja predominÃo de espécies cespitosas de baixo valor nutricional como Andropogon hypogynus. Em ambas as sub-regiões observaram-se dominância de áreas savânicas sazonalmente inundáveis, o que mostra a dinâmica destas áreas com espécies arbustivas adaptadas ao ciclo de inundação. The map presented here contains the main landscape units of the Nhecolândia and Poconé sub-regions of the Pantanal wetland. The map is based on the identification of dominant vegetation types and the flooding degree. The Nhecolândia sub-region was dominated by savannas seasonally flooded formations (41%) and the Poconé sub-region was dominanted by seasonally flooded forests (26%). The domain of forests was mainly due to cambará (Vochysia divergens). Both sub-regions presented extenses savanna areas. Higher quality natural pastures were situated on the flooding areas, mainly on lower relief. In the intermediate areas, there is dominance of lower quality cespitous species as Andropogon hypogynus. In both sub-regions, there was dominance of savanna seasonally flooded formations, which shows the dynamic of these areas with woody speciess adapted to flooding cycle.bitstream/item/79837/1/BP105.pd
Non-Abelian Geometric Phases and Conductance of Spin-3/2 Holes
Angular momentum holes in semiconductor heterostructures are showed
to accumulate nonabelian geometric phases as a consequence of their motion. We
provide a general framework for analyzing such a system and compute conductance
oscillations for a simple ring geometry. We also analyze a figure-8 geometry
which captures intrinsically nonabelian interference effects.Comment: 4 pages, 3 figures (encapsulated PostScript) Replaced fig. 1 and fig.
Phase separation in double exchange systems
Ferromagnetic systems described by the double exchange model are
investigated. At temperatures close to the Curie temperature, and for a wide
range of doping levels, the system is unstable toward phase separation. The
chemical potential decreases upon increasing doping, due to the significant
dependence of the bandwidth on the number of carriers. The reduction of the
electronic bandwidth by spin disorder leads to an enormously enhanced
thermopower which peaks near T_c, with a sign opposite that predicted by a
rigid band model.Comment: 4 pages, 2 encapsulated PostScript figure
Contractile Function during Angiotensin-II Activation:Increased Nox2 Activity Modulates Cardiac Calcium Handling via Phospholamban Phosphorylation
AbstractBackgroundRenin-angiotensin system activation is a feature of many cardiovascular conditions. Activity of myocardial reduced nicotinamide adenine dinucleotide phosphate oxidase 2 (NADPH oxidase 2 or Nox2) is enhanced by angiotensin II (Ang II) and contributes to increased hypertrophy, fibrosis, and adverse remodeling. Recent studies found that Nox2-mediated reactive oxygen species production modulates physiological cardiomyocyte function.ObjectivesThis study sought to investigate the effects of cardiomyocyte Nox2 on contractile function during increased Ang II activation.MethodsWe generated a cardiomyocyte-targeted Nox2-transgenic mouse model and studied the effects of in vivo and ex vivo Ang II stimulation, as well as chronic aortic banding.ResultsChronic subpressor Ang II infusion induced greater cardiac hypertrophy in transgenic than wild-type mice but unexpectedly enhanced contractile function. Acute Ang II treatment also enhanced contractile function in transgenic hearts in vivo and transgenic cardiomyocytes ex vivo. Ang II–stimulated Nox2 activity increased sarcoplasmic reticulum (SR) Ca2+ uptake in transgenic mice, increased the Ca2+ transient and contractile amplitude, and accelerated cardiomyocyte contraction and relaxation. Elevated Nox2 activity increased phospholamban phosphorylation in both hearts and cardiomyocytes, related to inhibition of protein phosphatase 1 activity. In a model of aortic banding–induced chronic pressure overload, heart function was similarly depressed in transgenic and wild-type mice.ConclusionsWe identified a novel mechanism in which Nox2 modulates cardiomyocyte SR Ca2+ uptake and contractile function through redox-regulated changes in phospholamban phosphorylation. This mechanism can drive increased contractility in the short term in disease states characterized by enhanced renin-angiotensin system activation
Phase separation and enhanced charge-spin coupling near magnetic transitions
The generic changes of the electronic compressibility in systems which show
magnetic instabilities is studied. It is shown that, when going into the
ordered phase, the compressibility is reduced by an amount comparable to the
its original value, making charge instabilities also possible. We discuss,
within this framework, the tendency towards phase separation of the double
exchange systems, the pyrochlores, and other magnetic materials
Improved X-ray detection and particle identification with avalanche photodiodes
Avalanche photodiodes are commonly used as detectors for low energy x-rays.
In this work we report on a fitting technique used to account for different
detector responses resulting from photo absorption in the various APD layers.
The use of this technique results in an improvement of the energy resolution at
8.2 keV by up to a factor of 2, and corrects the timing information by up to 25
ns to account for space dependent electron drift time. In addition, this
waveform analysis is used for particle identification, e.g. to distinguish
between x-rays and MeV electrons in our experiment.Comment: 6 pages, 6 figure
First Results from HaloSat – A CubeSat to Study the Hot Galactic Halo
HaloSat is the first CubeSat for astrophysics funded by NASA\u27s Science Mission Directorate and is designed to map soft X-ray oxygen line emission across the sky in order to constrain the mass and spatial distribution of hot gas in the Milky Way. HaloSat will help determine if hot halos with temperatures near a million degrees bound to galaxies make a significant contribution to the cosmological budget of the normal matter (baryons). HaloSat was deployed from the International Space Station in July 2018 and began routine science operations in October 2018. We describe the on-orbit performance including calibration of the X-ray detectors and initial scientific results including an observation of a halo field and an observation of solar wind charge exchange emission from the helium-focusing cone
Planet Populations as a Function of Stellar Properties
Exoplanets around different types of stars provide a window into the diverse
environments in which planets form. This chapter describes the observed
relations between exoplanet populations and stellar properties and how they
connect to planet formation in protoplanetary disks. Giant planets occur more
frequently around more metal-rich and more massive stars. These findings
support the core accretion theory of planet formation, in which the cores of
giant planets form more rapidly in more metal-rich and more massive
protoplanetary disks. Smaller planets, those with sizes roughly between Earth
and Neptune, exhibit different scaling relations with stellar properties. These
planets are found around stars with a wide range of metallicities and occur
more frequently around lower mass stars. This indicates that planet formation
takes place in a wide range of environments, yet it is not clear why planets
form more efficiently around low mass stars. Going forward, exoplanet surveys
targeting M dwarfs will characterize the exoplanet population around the lowest
mass stars. In combination with ongoing stellar characterization, this will
help us understand the formation of planets in a large range of environments.Comment: Accepted for Publication in the Handbook of Exoplanet
From cheek swabs to consensus sequences : an A to Z protocol for high-throughput DNA sequencing of complete human mitochondrial genomes
Background: Next-generation DNA sequencing (NGS) technologies have made huge impacts in many fields of biological research, but especially in evolutionary biology. One area where NGS has shown potential is for high-throughput sequencing of complete mtDNA genomes (of humans and other animals). Despite the increasing use of NGS technologies and a better appreciation of their importance in answering biological questions, there remain significant obstacles to the successful implementation of NGS-based projects, especially for new users.
Results: Here we present an ‘A to Z’ protocol for obtaining complete human mitochondrial (mtDNA) genomes – from DNA extraction to consensus sequence. Although designed for use on humans, this protocol could also be used to sequence small, organellar genomes from other species, and also nuclear loci. This protocol includes DNA extraction, PCR amplification, fragmentation of PCR products, barcoding of fragments, sequencing using the 454 GS FLX platform, and a complete bioinformatics pipeline (primer removal, reference-based mapping, output of coverage plots and SNP calling).
Conclusions: All steps in this protocol are designed to be straightforward to implement, especially for researchers who are undertaking next-generation sequencing for the first time. The molecular steps are scalable to large numbers (hundreds) of individuals and all steps post-DNA extraction can be carried out in 96-well plate format. Also, the protocol has been assembled so that individual ‘modules’ can be swapped out to suit available resources
Spatial variability of apparent electrical conductivity and soil properties in a coffee production field
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