1,167 research outputs found
Leptophis Ahaetulla (linnaeus, 1758) (serpentes, Colubridae): First Record For The State Of Rio Grande Do Sul, Brazil
We present the first record of Leptophis ahaetulla for the State of Rio Grande do Sul, Brazil. Between November and December 2014, and February 2015, three specimens were found, respectively: one male dead on a highway at the Parque Estadual do Espinilho, a conservation unit located at the municipality of Barra do Quaraí; and two females collected in an anthropic landscape of Salso farm at the municipality of Uruguaiana, Rio Grande do Sul, Brazil. Meristic data and coloration enables the identification of these specimens as Leptophis ahaetulla marginatus. © 2016 Check List and Authors.12
Decomposition and nutrient release of leguminous plants in coffee agroforestry systems.
Leguminous plants used as green manure are an important nutrient source for coffee plantations, especially for soils with low nutrient levels. Field experiments were conducted in the Zona da Mata of Minas Gerais State, Brazil to evaluate the decomposition and nutrient release rates of four leguminous species used as green manures (Arachis pintoi, Calopogonium mucunoides, Stizolobium aterrimum and
Stylosanthes guianensis) in a coffee agroforestry system under two different climate conditions. The initial N contents in plant residues varied from 25.7 to 37.0 g kg-1 and P from 2.4 to 3.0 g kg-1. The lignin/N, lignin/polyphenol and(lignin+polyphenol)/N ratios were low in all residues studied. Mass loss rates were highest in the first 15 days, when 25 % of the residues were decomposed. From 15 to 30 days, the decomposition rate decreased on both farms. On the farm in Pedra Dourada (PD), the decomposition constant k increased in the order C. mucunoides < S. aterrimum < S. guianensis < A. pintoi. On the farm in Araponga (ARA), there was no difference in the decomposition rate among leguminous plants. The N release rates varied from 0.0036 to 0.0096 d-1. Around 32 % of the total N content in the plant material was released in the first 15 days. In ARA, the N concentration in the S. aterrimum residues was always significantly higher than in the other residues. At the end of 360 days, the N released was 78 % in ARA and 89 % in PD of the initial content. Phosphorus was the most rapidly released nutrient (k values from 0.0165 to 0.0394 d-1). Residue decomposition and nutrient release did not correlate with initial residue chemistry and biochemistry, but differences in climatic conditions between the two study sites modified the decomposition rate constants
Field theoretic approach to metastability in the contact process
A quantum field theoretic formulation of the dynamics of the Contact Process
on a regular graph of degree z is introduced. A perturbative calculation in
powers of 1/z of the effective potential for the density of particles phi(t)
and an instantonic field psi(t) emerging from the quantum formalism is
performed. Corrections to the mean-field distribution of densities of particles
in the out-of-equilibrium stationary state are derived in powers of 1/z.
Results for typical (e.g. average density) and rare fluctuation (e.g. lifetime
of the metastable state) properties are in very good agreement with numerical
simulations carried out on D-dimensional hypercubic (z=2D) and Cayley lattices.Comment: Final published version; 20 pages, 5 figure
Potent and Broad-Spectrum Antimicrobial Activity of Analogs from the Scorpion Peptide Stigmurin
Scorpion venom constitutes a rich source of biologically active compounds with high potential for therapeutic and biotechnological applications that can be used as prototypes for the design of new drugs. The aim of this study was to characterize the structural conformation, evaluate the antimicrobial activity, and gain insight into the possible action mechanism underlying it, for two new analog peptides of the scorpion peptide Stigmurin, named StigA25 and StigA31. The amino acid substitutions in the native sequence for lysine residues resulted in peptides with higher positive net charge and hydrophobicity, with an increase in the theoretical helical content. StigA25 and StigA31 showed the capacity to modify their structural conformation according to the environment, and were stable to pH and temperature variation-results similar to the native peptide. Both analog peptides demonstrated broad-spectrum antimicrobial activity in vitro, showing an effect superior to that of the native peptide, being non-hemolytic at the biologically active concentrations. Therefore, this study demonstrates the therapeutic potential of the analog peptides from Stigmurin and the promising approach of rational drug design based on scorpion venom peptide to obtain new anti-infective agents.publishersversionpublishe
Charged BTZ-like Black Holes in Higher Dimensions
Motivated by many worthwhile paper about (2 + 1)-dimensional BTZ black holes,
we generalize them to to (n + 1)-dimensional solutions, so called BTZ-like
solutions. We show that the electric field of BTZ-like solutions is the same as
(2 + 1)-dimensional BTZ black holes, and also their lapse functions are
approximately the same, too. By these similarities, it is also interesting to
investigate the geometric and thermodynamics properties of the BTZ-like
solutions. We find that, depending on the metric parameters, the BTZ-like
solutions may be interpreted as black hole solutions with inner (Cauchy) and
outer (event) horizons, an extreme black hole or naked singularity. Then, we
calculate thermodynamics quantities and conserved quantities, and show that
they satisfy the first law of thermodynamics. Finally, we perform a stability
analysis in the canonical ensemble and show that the BTZ-like solutions are
stable in the whole phase space.Comment: 5 pages, two column format, one figur
First attempt at measuring the CMB cross-polarization
We compute upper limits on CMB cross-polarization by cross-correlating the
PIQUE and Saskatoon experiments. We also discuss theoretical and practical
issues relevant to measuring cross-polarization and illustrate them with
simulations of the upcoming BOOMERanG 2002 experiment. We present a method that
separates all six polarization power spectra (TT, EE, BB, TE, TB, EB) without
any other "leakage" than the familiar EE-BB mixing caused by incomplete sky
coverage. Since E and B get mixed, one might expect leakage between TE and TB,
between EE and EB and between BB and EB - our method eliminates this by
preserving the parity symmetry under which TB and EB are odd and the other four
power spectra are even.Comment: Polarization movies can be found at
http://www.hep.upenn.edu/~angelica/polarization.htm
Spanning forests and the q-state Potts model in the limit q \to 0
We study the q-state Potts model with nearest-neighbor coupling v=e^{\beta
J}-1 in the limit q,v \to 0 with the ratio w = v/q held fixed. Combinatorially,
this limit gives rise to the generating polynomial of spanning forests;
physically, it provides information about the Potts-model phase diagram in the
neighborhood of (q,v) = (0,0). We have studied this model on the square and
triangular lattices, using a transfer-matrix approach at both real and complex
values of w. For both lattices, we have computed the symbolic transfer matrices
for cylindrical strips of widths 2 \le L \le 10, as well as the limiting curves
of partition-function zeros in the complex w-plane. For real w, we find two
distinct phases separated by a transition point w=w_0, where w_0 = -1/4 (resp.
w_0 = -0.1753 \pm 0.0002) for the square (resp. triangular) lattice. For w >
w_0 we find a non-critical disordered phase, while for w < w_0 our results are
compatible with a massless Berker-Kadanoff phase with conformal charge c = -2
and leading thermal scaling dimension x_{T,1} = 2 (marginal operator). At w =
w_0 we find a "first-order critical point": the first derivative of the free
energy is discontinuous at w_0, while the correlation length diverges as w
\downarrow w_0 (and is infinite at w = w_0). The critical behavior at w = w_0
seems to be the same for both lattices and it differs from that of the
Berker-Kadanoff phase: our results suggest that the conformal charge is c = -1,
the leading thermal scaling dimension is x_{T,1} = 0, and the critical
exponents are \nu = 1/d = 1/2 and \alpha = 1.Comment: 131 pages (LaTeX2e). Includes tex file, three sty files, and 65
Postscript figures. Also included are Mathematica files forests_sq_2-9P.m and
forests_tri_2-9P.m. Final journal versio
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