The Anomalous Hall effect in re-entrant AuFe alloys and the real space Berry phase

The Hall effect has been studied in a series of AuFe samples in the re-entrant concentration range, as well as in the spin glass range. The data demonstrate that the degree of canting of the local spins strongly modifies the anomalous Hall effect, in agreement with theoretical predictions associating canting, chirality and a real space Berry phase. The canonical parametrization of the Hall signal for magnetic conductors becomes inappropriate when local spins are canted.Comment: 4 pages, 1 eps figur

Conditions for the onset of the current filamentation instability in the laboratory

Current Filamentation Instability (CFI) is capable of generating strong magnetic fields relevant to explain radiation processes in astrophysical objects and lead to the onset of particle acceleration in collisionless shocks. Probing such extreme scenarios in the laboratory is still an open challenge. In this work, we investigate the possibility of using neutral $e^{-}$ $e^{+}$ beams to explore the CFI with realistic parameters, by performing 2D particle-in-cell simulations. We show that CFI can occur unless the rate at which the beam expands due to finite beam emittance is larger than the CFI growth rate and as long as the role of competing electrostatic two-stream instability (TSI) is negligible. We also show that the longitudinal energy spread, typical of plasma based accelerated electron-positron fireball beams, plays a minor role in the growth of CFI in these scenarios

Origin and consequences of chromosomal inversions in the virilis group of Drosophila

In Drosophila, large variations in rearrangement rate have been reported among different lineages and among Muller’s elements. Nevertheless, the mechanisms that are involved in the generation of inversions, their increase in frequency, as well as their impact on the genome are not completely understood. This is in part due to the lack of comparative studies on species distantly related to Drosophila melanogaster. Therefore, we sequenced and assembled the genomes of two species of the virilis phylad (Drosophila novamexicana [15010-1031.00] and Drosophila americana [SF12]), which are diverging from D. melanogaster for more than 40 Myr. Based on these data, we identified the precise location of six novel inversion breakpoints. A molecular characterization provided clear evidence that DAIBAM (a miniature inverted–repeat transposable element) was involved in the generation of eight out of the nine inversions identified. In contrast to what has been previously reported for D. melanogaster and close relatives, ectopic recombination is thus the prevalent mechanism of generating inversions in species of the virilis phylad. Using pool-sequencing data for three populations of D. americana, we also show that common polymorphic inversions create a high degree of genetic differentiation between populations for chromosomes X, 4, and 5 over large physical distances. We did not find statistically significant differences in expression levels between D. americana (SF12) and D. novamexicana (15010-1031.00) strains for the three genes surveyed (CG9588, Fig 4, and fab1) flanking three inversion breakpoints.This article is a result of the project Norte-01-0145-FEDER-000008—Porto Neurosciences and Neurologic Disease Research Initiative at I3S, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). N.P. and M.R. are funded by the Emmy Noether Programme of the Deutsche Forschungsgemeinschaft (Grant Number: PO 1648/3-1 to N.P.). We would like to thank the Transcriptome Analysis Lab (TAL) (University Medical Center Göttingen, UMG) in Göttingen for the Illumina sequencing

Rapid detection of microorganisms by peptide nucleic acids

Peptide nucleic acid (PNA) molecules are DNA mimics, where the negatively charged sugarphosphate backbone is replaced by an achiral, neutral polyamide backbone formed by repetitive units of N–(2-aminoethyl) glycine. Due to their superior hybridization properties, PNA probes to detect pathogens by fluorescence in situ hybridization (FISH) have been challenging DNA probes over the last few years. In our lab, we have already designed and developed several new probes for the specific detection of bacterial species such as Helicobacter pylori, Cronobacter spp., Staphylococcus epidermidis, Salmonella spp. and Proteus spp. [1, 2]. During development and validation, probes are tested against several related species, and have been shown to be highly specific for the microorganisms of interest. All techniques were optimized in slides and then adapted for different types of samples, depending on the microorganism: H. pylori probe has been developed to work on gastric biopsies and will soon be tested in a clinical trial for a potentially commercial application; Cronobacter spp. is a major contaminant of milk-based powdered infant formula, and as such a probe to detect the pathogen after pre-enrichment of contaminated milk was devised; S. epidermidis, which is frequently present on the skin of humans, had methods developed for its identification in blood samples and catheters; and analysis of interest for Salmonella and Proteus spp. included pipes of drinking water distribution systems and urinary samples. Future work with PNA probes will involve simultaneous detection of several species in a single sample and quantitative signal detection by flow cytometry

Optimization conditions of UV-C radiation combined with ultrasound-assisted extraction of cherry tomato (Lycopersicon esculentum) lycopene extract

The aim of this work was to study the effect of UV-C radiation on ultrasound assisted extraction (UAE) of cherry tomato bioactive compounds. Cherry tomatoes were exposed to two UV-C radiation doses (0.5 and 1.0 J cm−2 ) and stored at 20 ± 0.5 oC for 7 days. Next, they were lyophilized, and the bioactive compounds were extracted by UAE at 20 KHz. To evaluate the effectiveness of the extraction process of the bioactive compounds, a CCRD (central composite rotational design) was used together with RSM (response surface methodology), for extraction times from 4 to 12 minutes and concentrations (g of lyophilized product / L of ethanol) of 1:10, 1:20 and 1:30. The extracts obtained from the irradiated tomatoes presented 5.8 times more lycopene content than the controls and higher antioxidant activity was obtained for 4 and 8 min, in the concentrations 1:10 and 1:20 (m v−1). Through numerical model optimization, optimal extraction conditions were obtained. The results demonstrated that by previously irradiating tomatoes with UV-C light, the UAE yielded considerably higher amounts of lycopene and other bioactives.CNPq (National Council of Technological and Scientific Development, Brazil), Erasmus Mundus action 2; Fellow Mundus Project; Department of Chemical Engineering and Food Engineering (UFSC - Brazil) and the Department of Food Engineering (UAlg - Portugal) .info:eu-repo/semantics/publishedVersio

Electronic state spectroscopy of C₂Cl₄

The VUV spectrum of C2Cl4 is reported in the energy range 3.8-10.8 eV (325-115 nm). Several photoabsorption features are observed for the first time, including a very weak low-lying band which is provisionally attributed to a π → π* triplet transition. Recent ab initio calculations of the molecule’s electronic transitions [Arulmozhiraja et al. J. Chem. Phys. 129 (2008) 174506] provide the basis for the present assignments below 8.5 eV. An extended ndπ series is proposed to account for several higher-energy Rydberg bands. The identification of vibrational structure, dominated by symmetric C=C and CCl2 stretching in excitations from the HOMO, largely agrees with previous spectroscopic studies. The present absolute photoabsorption cross sections cover a wider energy range than the previous measurements and are used to calculate UV photolysis lifetimes of this aeronomic molecule at altitudes between 20 and 50 km

Controlo visual de um tapete-rolante

No presente artigo é apresentado o trabalho realizado no Laboratório de Sistemas Industriais, onde se pretende controlar a passagem de objectos num tapete rolante através de visão por computador. O sistema desenvolvido consiste num tapete rolante accionado por um servo motor da OMRON, com transmissão por correia. O controlo do servo motor é realizado por computador através de uma placa da National Instruments PCI-7344 com o adaptador UMI-7764. O sistema de visão consiste numa placa Matrox Meteor II e uma câmara CCD a cores. Pretende-se controlar a velocidade do tapete em função do numero de objectos a identificar e do tempo de processamento do anel de visão. Para tal foi necessário calibrar o sistema de visão, baseado num PC- Pentium II a 350 MHz com 32 Mb de RAM, tendo o software sido desenvolvido em Visual C++. O sistema de controlo encontra-se centralizado num PC-Pentium III a 850 MHz com 128 Mb de RAM, tendo o software sido desenvolvido no programa LABVIE