159 research outputs found
Estrutura e produção das florestas naturais ao longo do Rio Branco no Território Federal de Roraima
This paper is a summary of a forest inventory research project carried out in North Brazil by the Universidade Federal de Santa Maria - RS, specifically, in the Federal Territory of Roraima, along the Branco River, comprising an area of aproximately 46.000ha.An attemp was made to describe all the forest types of the region from the ecological and timber stock points of view. Considerations about the current exploration process in the area and the trunk vitality of the various species were made.O presente trabalho corresponde a uma sĂntese do inventĂĄrio florestal realizado no TerritĂłrio Federal de Roraima, no Norte do PaĂs, na regiĂŁo de influĂŞncia do Rio Branco, numa ĂĄrea de aproximadamente 46.000 ha, pela Universidade Federal de Santa Maria.Procurou-se descrever os tipos florestais encontrados na regiĂŁo sob o ponto de vista ecolĂłgico e de estoque de madeira, efetuando-se consideraçþes sobre o potencial das florestas, o processo e o estĂĄgio de exploração em que se encontram e a vitalidade dos troncos das diferentes espĂŠcies encontradas
Estrutura e produção das florestas naturais ao longo do Rio Branco no Território Federal de Roraima
This paper is a summary of a forest inventory research project carried out in North Brazil by the Universidade Federal de Santa Maria - RS, specifically, in the Federal Territory of Roraima, along the Branco River, comprising an area of aproximately 46.000ha.An attemp was made to describe all the forest types of the region from the ecological and timber stock points of view. Considerations about the current exploration process in the area and the trunk vitality of the various species were made.O presente trabalho corresponde a uma sĂntese do inventĂĄrio florestal realizado no TerritĂłrio Federal de Roraima, no Norte do PaĂs, na regiĂŁo de influĂŞncia do Rio Branco, numa ĂĄrea de aproximadamente 46.000 ha, pela Universidade Federal de Santa Maria.Procurou-se descrever os tipos florestais encontrados na regiĂŁo sob o ponto de vista ecolĂłgico e de estoque de madeira, efetuando-se consideraçþes sobre o potencial das florestas, o processo e o estĂĄgio de exploração em que se encontram e a vitalidade dos troncos das diferentes espĂŠcies encontradas
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Identification of a Novel Gene for Diabetic Traits in Rats, Mice, and Humans
The genetic basis of type 2 diabetes remains incompletely defined despite the use of multiple genetic strategies. Multiparental populations such as heterogeneous stocks (HS) facilitate gene discovery by allowing fine mapping to only a few megabases, significantly decreasing the number of potential candidate genes compared to traditional mapping strategies. In the present work, we employed expression and sequence analysis in HS rats (Rattus norvegicus) to identify Tpcn2 as a likely causal gene underlying a 3.1-Mb locus for glucose and insulin levels. Global gene expression analysis on liver identified Tpcn2 as the only gene in the region that is differentially expressed between HS rats with glucose intolerance and those with normal glucose regulation. Tpcn2 also maps as a cis-regulating expression QTL and is negatively correlated with fasting glucose levels. We used founder sequence to identify variants within this region and assessed association between 18 variants and diabetic traits by conducting a mixed-model analysis, accounting for the complex family structure of the HS. We found that two variants were significantly associated with fasting glucose levels, including a nonsynonymous coding variant within Tpcn2. Studies in Tpcn2 knockout mice demonstrated a significant decrease in fasting glucose levels and insulin response to a glucose challenge relative to those in wild-type mice. Finally, we identified variants within Tpcn2 that are associated with fasting insulin in humans. These studies indicate that Tpcn2 is a likely causal gene that may play a role in human diabetes and demonstrate the utility of multiparental populations for positionally cloning genes within complex loci
Material properties of ex-vivo milk chocolate boluses examined in relation to texture perception
The texture perception of chocolate products is a major driver for consumer liking and the popularity of this confectionary category. Whilst some texture attributes are clearly linked to the material properties of the chocolate bar itself, others are closer related to the properties of the chocolate bolus. However, little is known around the material properties of chocolate boluses. Hence the aim of this study was to gain more in-depth insights into this area and to evaluate how chocolate bolus material properties link to texture and mouthfeel perception. Boluses prepared from four milk chocolates were analysed for microstructure, particle size, and composition and friction properties. The boluses showed the expected oil-in-water emulsion microstructure. The emulsion droplets were composed of fat and milk protein with clear evidence for presence of milk protein not only at the droplet interface but also in the droplet bulk phase. The type of adsorbed milk protein depended on the presence or absence of interfacially adsorbed cocoa solids, grouping the four chocolates into two pairs. The chocolate boluses showed increased friction compared to saliva and at low sliding speed the friction coefficients were lower for boluses with interfacially adsorbed cocoa solids. Perceived differences in mouthcoating were reflected in the mixed regime of the Stribeck curve. Thickness perception on the other hand was reflected in the hydrodynamic regime of the friction curves. This research has highlighted promise in analysing material properties of chocolate boluses in view to understanding perceived texture
Herschel-ATLAS: Multi-wavelength SEDs and physical properties of 250 micron-selected galaxies at z < 0.5
We present a pan-chromatic analysis of an unprecedented sample of 1402 250
micron-selected galaxies at z < 0.5 (mean z = 0.24) from the Herschel-ATLAS
survey. We complement our Herschel 100-500 micron data with UV-K-band
photometry from the Galaxy And Mass Assembly (GAMA) survey and apply the
MAGPHYS energy-balance technique to produce pan-chromatic SEDs for a
representative sample of 250 micron selected galaxies spanning the most recent
5 Gyr of cosmic history. We derive estimates of physical parameters, including
star formation rates, stellar masses, dust masses and infrared luminosities.
The typical H-ATLAS galaxy at z < 0.5 has a far-infrared luminosity in the
range 10^10 - 10^12 Lsolar (SFR: 1-50 Msolar/yr) thus is broadly representative
of normal star forming galaxies over this redshift range. We show that 250
micron-selected galaxies contain a larger mass of dust at a given infra-red
luminosity or star formation rate than previous samples selected at 60 micron
from IRAS. We derive typical SEDs for H-ATLAS galaxies, and show that the
emergent SED shape is most sensitive to specific star formation rate. The
optical-UV SEDs also become more reddened due to dust at higher redshifts. Our
template SEDs are significantly cooler than existing infra-red templates. They
may therefore be most appropriate for inferring total IR luminosities from
moderate redshift submillimetre selected samples and for inclusion in models of
the lower redshift submillimetre galaxy populations.Comment: 26 pages, 24 figures, Accepted by MNRA
Agatha: : disentangling periodic signals from correlated noise in a periodogram framework
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. Š: 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Periodograms are used as a key significance assessment and visualisation tool to display the significant periodicities in unevenly sampled time series. We introduce a framework of periodograms, called "Agatha", to disentangle periodic signals from correlated noise and to solve the 2-dimensional model selection problem: signal dimension and noise model dimension. These periodograms are calculated by applying likelihood maximization and marginalization and combined in a self-consistent way. We compare Agatha with other periodograms for the detection of Keplerian signals in synthetic radial velocity data produced for the Radial Velocity Challenge as well as in radial velocity datasets of several Sun-like stars. In our tests we find Agatha is able to recover signals to the adopted detection limit of the radial velocity challenge. Applied to real radial velocity, we use Agatha to confirm previous analysis of CoRoT-7 and to find two new planet candidates with minimum masses of 15.1 and 7.08 orbiting HD177565 and HD41248, with periods of 44.5 d and 13.4 d, respectively. We find that Agatha outperforms other periodograms in terms of removing correlated noise and assessing the significances of signals with more robust metrics. Moreover, it can be used to select the optimal noise model and to test the consistency of signals in time. Agatha is intended to be flexible enough to be applied to time series analyses in other astronomical and scientific disciplines. Agatha is available at http://www.agatha.herts.ac.uk.Peer reviewe
Platelet activation attracts a subpopulation of effector monocytes to sites of Leishmania major infection
Leishmania infection triggers the recruitment of Gr1+ monocytes to the site of infection via platelet-derived PDGF and subsequent CCL2 production
GAMA/H-ATLAS: the ultraviolet spectral slope and obscuration in galaxies
We use multiwavelength data from the Galaxy And Mass Assembly (GAMA) and Herschel-ATLAS (H-ATLAS) surveys to compare the relationship between various dust obscuration measures in galaxies. We explore the connections between the ultraviolet (UV) spectral slope, β, the Balmer decrement and the far-infrared (FIR) to 150 nm far-ultraviolet (FUV) luminosity ratio. We explore trends with galaxy mass, star formation rate (SFR) and redshift in order to identify possible systematics in these various measures. We reiterate the finding of other authors that there is a large scatter between the Balmer decrement and the β parameter, and that β may be poorly constrained when derived from only two broad passbands in the UV. We also emphasize that FUV-derived SFRs, corrected for dust obscuration using β, will be overestimated unless a modified relation between β and the attenuation factor is used. Even in the optimum case, the resulting SFRs have a significant scatter, well over an order of magnitude. While there is a stronger correlation between the IR-to-FUV luminosity ratio and β parameter than with the Balmer decrement, neither of these correlations are particularly tight, and dust corrections based on β for high-redshift galaxy SFRs must be treated with caution. We conclude with a description of the extent to which the different obscuration measures are consistent with each other as well as the effects of including other galactic properties on these correlation
Cognitive and Socio-Emotional Deficits in Platelet-Derived Growth Factor Receptor-β Gene Knockout Mice
Platelet-derived growth factor (PDGF) is a potent mitogen. Extensive in vivo studies of PDGF and its receptor (PDGFR) genes have reported that PDGF plays an important role in embryogenesis and development of the central nervous system (CNS). Furthermore, PDGF and the β subunit of the PDGF receptor (PDGFR-β) have been reported to be associated with schizophrenia and autism. However, no study has reported on the effects of PDGF deletion on mice behavior. Here we generated novel mutant mice (PDGFR-β KO) in which PDGFR-β was conditionally deleted in CNS neurons using the Cre/loxP system. Mice without the Cre transgene but with floxed PDGFR-β were used as controls. Both groups of mice reached adulthood without any apparent anatomical defects. These mice were further examined by conducting several behavioral tests for spatial memory, social interaction, conditioning, prepulse inhibition, and forced swimming. The test results indicated that the PDGFR-β KO mice show deficits in all of these areas. Furthermore, an immunohistochemical study of the PDGFR-β KO mice brain indicated that the number of parvalbumin (calcium-binding protein)-positive (i.e., putatively γ-aminobutyric acid-ergic) neurons was low in the amygdala, hippocampus, and medial prefrontal cortex. Neurophysiological studies indicated that sensory-evoked gamma oscillation was low in the PDGFR-β KO mice, consistent with the observed reduction in the number of parvalbumin-positive neurons. These results suggest that PDGFR-β plays an important role in cognitive and socioemotional functions, and that deficits in this receptor may partly underlie the cognitive and socioemotional deficits observed in schizophrenic and autistic patients
Flexibility of a biotinylated ligand in artificial metalloenzymes based on streptavidinâan insight from molecular dynamics simulations with classical and ab initio force fields
In the field of enzymatic catalysis, creating activity from a non catalytic scaffold is a daunting task. Introduction of a catalytically active moiety within a protein scaffold offers an attractive means for the creation of artificial metalloenzymes. With this goal in mind, introduction of a biotinylated d6-piano-stool complex within streptavidin (SAV) affords enantioselective artificial transfer-hydrogenases for the reduction of prochiral ketones. Based on an X-ray crystal structure of a highly selective hybrid catalyst, displaying significant disorder around the biotinylated catalyst [Ρ6-(p-cymene)Ru(Biot-p-L)Cl], we report on molecular dynamics simulations to shed light on the proteinâcofactor interactions and contacts. The results of these simulations with classical force field indicate that the SAV-biotin and SAV-catalyst complexes are more stable than ligand-free SAV. The point mutations introduced did not affect significantly the overall behavior of SAV and, unexpectedly, the P64G substitution did not provide additional flexibility to the protein scaffold. The metal-cofactor proved to be conformationally flexible, and the S112K or P64G mutants proved to enhance this effect in the most pronounced way. The network of intermolecular hydrogen bonds is efficient at stabilizing the position of biotin, but much less at fixing the conformation of an extended biotinylated ligand. This leads to a relative conformational freedom of the metal-cofactor, and a poorly localized catalytic metal moiety. MD calculations with ab initio potential function suggest that the hydrogen bonds alone are not sufficient factors for full stabilization of the biotin. The hydrophobic biotin-binding pocket (and generally protein scaffold) maintains the hydrogen bonds between biotin and protein
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