First stars XVI. STIS/HST abundances of heavy-elements in the uranium-rich star CS 31082-001

Detailed abundances of the elements produced by r-process nucleosynthesis in various circumstances are our best observational clues to their origin, since the site(s) of r-element production is(are) still not known with certainty. A small fraction of extremely metal-poor (EMP) stars exhibit excesses of heavy neutron-capture elements produced in the r-process, and CS 31082-001 is among the 4 well-known r-process-enhanced EMP stars. Observations with HST/STIS provide abundances for elements observable only from the UV region. Here we aim to supplement the optical data with abundances from near-UV spectroscopy of the first and second peak of the r-elements, which are crucial to giving insight into the nucleosynthesis of the elements beyond iron. The UVES spectrum provided additional measurements, thereby improving the previous results. The spectra were analyzed with the OSMARCS LTE model atmosphere and with a consistent approach based on the spectrum synthesis code Turbospectrum to derive abundances of heavy elements in CS 31082-001, using updated oscillator strengths from the recent literature. We computed synthetic spectra for all lines of the elements of interest, checking for proper intensities and possible blends. We combined the abundances of heavy elements derived in previous works with the derivation of abundances from all reliable new list of lines, for the first and second peaks of r-elements. We were able to derive new abundances for 23 n-elements, 6 of them - Ge, Mo, Lu, Ta, W, and Re - were not available in previous works, making this star the most complete r-II object studied, with a total of 37 detections of n-capture elements. We also present the first NLTE+3D lead abundance in this star. The results provide improved constraints on the nature of the r-process.Comment: 20 pages, 21 figures, 3 tables. Accepted for publication in Astronomy and Astrophysic

Spin-1/2 Heisenberg-Antiferromagnet on the Kagome Lattice: High Temperature Expansion and Exact Diagonalisation Studies

For the spin-$\frac{1}{2}$ Heisenberg antiferromagnet on the Kagom\'e lattice we calculate the high temperature series for the specific heat and the structure factor. A comparison of the series with exact diagonalisation studies shows that the specific heat has further structure at lower temperature in addition to a high temperature peak at $T\approx 2/3$. At $T=0.25$ the structure factor agrees quite well with results for the ground state of a finite cluster with 36 sites. At this temperature the structure factor is less than two times its $T=\infty$ value and depends only weakly on the wavevector $\bf q$, indicating the absence of magnetic order and a correlation length of less than one lattice spacing. The uniform susceptibility has a maximum at $T\approx 1/6$ and vanishes exponentially for lower temperatures.Comment: 15 pages + 5 figures, revtex, 26.04.9

Análise de marmoreio de contra-filé através de imagens obtidas por Tomografia de Ressonância Magnética.

bitstream/CNPDIA-2009-09/11895/1/CT98_2008.pd

Possible chiral phase transition in two-dimensional solid 3^3He

We study a spin system with two- and four-spin exchange interactions on the triangular lattice, which is a possible model for the nuclear magnetism of solid $^3$He layers. It is found that a novel spin structure with scalar chiral order appears if the four-spin interaction is dominant. Ground-state properties are studied using the spin-wave approximation. A phase transition concerning the scalar chirality occurs at a finite temperature, even though the dimensionality of the system is two and the interaction has isotropic spin symmetry. Critical properties of this transition are studied with Monte Carlo simulations in the classical limit.Comment: 4 pages, Revtex, 4 figures, to appear in Phys.Rev.Let

Filamentous fungi in drinking water tanks of a water supply system in Recife-PE, Brazil

Drinking water reservoirs are widely used in various building constructions in Brazil for as a source of potable water for users. However, they are susceptible to the growth of microorganisms such as fungi. From these, several negative factors may ensue, namely, unpleasant odors and flavours, pigments, biofilm formation and mycotoxins. This is caused fungal resistance to treatment and disinfection. Brazilian law and those of other countries offer no encouragement for the research of the species of fungi that cause these problems. There are no legal limits as to the presence in drinking water. This study assesses the occurrence of filamentous fungi in drinking water reservoirs connected to the Alto do Céu distribution system located in Recife, Pernambuco, Brazil. Four monthly collections were carried out, in triplicate, at two fixed points in the network, at the same treatment area, and another 2.0 km away from this site. For water physicochemical characterization at the time of collection, pH, temperature and free residual chlorine were analyzed. Filamentous fungi were quantified by filtration through cellulose nitrate membrane with a 0.45 μm porosity. All strains were grown in Petri dishes containing Peptone Glucose, Rose Bengal Agar (PGRBA) and were incubated at 30°C for 48h. Fungal occurrence was quantified as colony forming units (CFU) per litre. Twenty-four samples were analyzed, and these accounted for 807 CFU. Considering the potential for water spreading diseases, and the high toxicity of fungi into account it is intended that this work may prompt the creation of acceptable parameters as to the presence of fungi in drinking water networks

Filamentous fungi in biofilms of water tanks in a supply system in Recife-PE, Brazil

Fungi cause detrimental organoleptic effects in water, and their presence may facilitate the occurrence of infections, allergic reactions and harmful effects from mycotoxins. Despite the lack of knowledge on the biological structure of filamentous fungi in biofilms, it is known that they can contribute with bacteria, yeasts, protozoa and viruses. Hence, this study analyzed, in situ, filamentous fungi in biofilms found in drinking water reservoirs of the distribution network in Alto do Céu, Recife, Pernambuco, Brazil. Biofilms were collected, in triplicate from samplers consisting of a polyethylene plate (4.0cm x 1.5cm) established in drinking water reservoirs. Four monthly collections were carried out between August and November 2011 at two fixed points. Polyethylene samplers were taken to the laboratory and washed with sterile water and transferred to Petri dishes containing medium Peptone, Glucose, Rose Bengal Agar (PGRBA). The plates were incubated at 30°C for 48h. The occurrence of fungi was reported as CFU/L. Fifty three colony forming units of fungi were quantified. For water physicochemical characterization at the time of collection, pH, temperature and free residual chlorine were analyzed. For detection of biofilms, a combination of two fluorescent techniques was used: (A) Fluorescent “in situ” hybridization (FISH) using a rDNA universal probe EUK516 (ACCAGACTTGCCCTCC 5’-3’, MWG Biotech, Ebersberg, Germany) labeled with cyanine Cy3 at the 5’ end and (B) Calcofluor White M2R (CW). After FISH and CW, the samples were observed under an epifluorescent microscope. Fungal filaments which formed biofilms in the distribution network were observed establishing biofilm formation. These results confirm the presence and relevance of filamentous fungi in structuring biofilms

Determinação das condições de qRT-PCR para genes envolvidos no fenômeno hard-to-cook em feijão carioca.

O fenômeno hard-to-cook promove a diminuição no amaciamento por cocção, alteração na palatabilidade e diminuição na disponibilidade de proteínas e carboidratos, prejudicando a comercialização dos grãos. Como parte de um estudo que prevê a caracterização físico-química, bioquímicas e moleculares associadas ao endurecimento dos grãos de feijão, este estudo objetiva ajustar e implementar protocolos que possibilitem a avaliação da expressão de genes alvos responsáveis pelo endurecimento