Effect of noise in open chaotic billiards

We investigate the effect of white-noise perturbations on chaotic trajectories in open billiards. We focus on the temporal decay of the survival probability for generic mixed-phase-space billiards. The survival probability has a total of five different decay regimes that prevail for different intermediate times. We combine new calculations and recent results on noise perturbed Hamiltonian systems to characterize the origin of these regimes, and to compute how the parameters scale with noise intensity and billiard openness. Numerical simulations in the annular billiard support and illustrate our results.Comment: To appear in "Chaos" special issue: "Statistical Mechanics and Billiard-Type Dynamical Systems"; 9 pages, 5 figure

Genetic diversity of two Portuguese populations of the pullet carpet shell Venerupis senegalensis, based on RAPD markers: contribution to a sustainable restocking program

The pullet carpet shell Venerupis senegalensis (=V. pullastra) is a commercially important species in Portugal, Spain, France, and Italy. In Portugal, this species was once abundant in the Ria Formosa (southern Portugal

Bioelectricity generation using long-term operated biocathode: RFLP based microbial diversity analysis

FRH/BPD/33864/2009 UIDB/50006/2020 UIDP/50006/2020In the present work, power generation and substrate removal efficiencies of long-term operated microbial fuel cells, containing abiotic cathodes and biocathodes, were evaluated for 220 days. Among the two microbial fuel cell (MFC) types, the one containing biocathode showed higher power density (54 mW/m2), current density (122 mA/m2) coulombic efficiency (33%), and substrate removal efficiency (94%) than the abiotic cathode containing MFC. Voltammetric analysis also witnessed higher and sustainable electron discharge for the MFC with biocathode, when compared with the abiotic cathode MFC. Over the tested period, both MFC have shown a cell voltage drop, after 150 and 165, days, for the MFC with biocathode and abiotic cathodes, respectively. Polymerase chain reaction (PCR) based restriction fragment length polymorphism (RFLP) analysis identified 281 clones. Bacteria belonging to Acinetobacter, Acidovorax, Pseudomonas and Burkholderia were observed in the abiotic cathode MFC. Bacteria belonging to Geobacter, Cupriavidus and Acidobacteria were observed in the biocathode MFC. Almost similar types of archaea (Methanosarcinales, Methanolinea, Nitrososphaera and Methanomicrobiales) were observed in both MFCs.publishersversionpublishe

Influence of hormonal replacement therapy in lipid peroxidation levels of postmenopausal women with different cardiovascular capacity

It has been suggested that exercise has a positive impact on the prevention and progression of cardiovascular disease (CVD). One of the main mechanisms is through the modification of lipoprotein levels and the risk of its oxidation, especially LDL lipoproteins. After menopause, women experience an increased incidence of cardiovascular disease. In contrast, women receiving hormonal replacement therapy (HRT) seem to be protected. The aim of this study was to infer how HRT affect lipid peroxidation levels in postmenopausal women with different levels of aerobic fitness. Design & Method: Sixty four women participate in this study, 32 of them receive HRT (group with HRT – GWHRT) (average age¼55.9 years, average weight¼ 66.9 kg and average high¼156.0 cm) and the remained 32 women didn’t receive HRT (group without HRT – GWOHRT) (average age¼61.0 years, average weight¼ 67.6 kg and average high¼154.3 cm). Total cholesterol (mg dL71), HDL-cholesterol (mg dL71), LDL-cholesterol (mg dL71) and triglycerides levels (mg dL71) have been analyzed in serum obtained from a blood sample collected after 8 hours of fasting, and measured in Dr. Lange LP20 according to the specific manufacturer instructions. Serum MDA concentration (ng L71) was determined by spectrophotometric method. Aerobic capacity (VO2max ml kg71 min71) was assessed according to an adaptation of Bruce protocol. Differences between groups were tested through Student t-test. A Spearman correlation was performed in order to test variables associations. Significance level was established at 5%.Results: Our results have found differences between groups in age (t¼3.018; p50.01), in VO2max (t¼73.774; p50.01) and in serum MDA concentration (t¼6.750; p50.01). The GWHRT were younger, had a higher VO2max (31.38 for GWHRT and 26.19 for GWOHRT), and had lower levels of serum MDA concentration (0.29 for GWHRT and 0.73 for GWOHRT) comparatively with those women from the GWOHRT. However, our results failed to find any differences between groups regarding serum triglycerides, total cholesterol, HDL-cholesterol, LDL-cholesterol or BMI. In this study, serum MDA concentration didn’t correlate with higher levels of lipid profile, as we might have expected, but correlate inversely with HRT (r¼7.726, p¼.00) and with VO2max (r¼7.287, p¼.02). Conclusion: Our results suggest that HRT should exert an antioxidant protective effect against lipid peroxidation, as well as exercise perhaps through the stimulation of antioxidant capacity

Gram-positive merA gene in gram-negative oral and urine bacteria

Clinical mercury resistant (Hgr) Gram-negative bacteria carrying Gram-positive mercury reductase (merA)-like genes were characterized using DNA–DNA hybridization, PCR and sequencing. A PCR assay was developed which discriminated between the merA genes related to Staphylococcus and those related to the Bacillus/Streptococcus merA genes by the difference in size of the PCR product. DNA sequence analysis correlated with the PCR assay. The merA genes from Acinetobacter junii, Enterobacter cloacae and Escherichia coli were sequenced and shared 98–99% identical nucleotide (nt) and 99.6–100% amino acid identity with the Staphylococcus aureus MerA protein. A fourth merA gene, from Pantoeae agglomerans, was partially sequenced (60%) and had 99% identical nt and 100% amino acid identity with the Streptococcus oralis MerA protein. All the Hgr Gram-negative bacteria transferred their Gram-positive merA genes to a Gram-positive Enterococcus faecalis recipient with the resulting transconjugants expressing mercury resistance. These Gram-positive merA genes join Gram-positive tetracycline resistance and Gram-positive macrolide resistance genes in their association with mobile elements which are able to transfer and express in Gram-negative bacteria.info:eu-repo/semantics/publishedVersio

Will Casuarina glauca Stress Resilience Be Maintained in the Face of Climate Change?

Actinorhizal plants have been regarded as promising species in the current climate change context due to their high tolerance to a multitude of abiotic stresses. While combined salt-heat stress effects have been studied in crop species, their impact on the model actinorhizal plant, Casuarina glauca, has not yet been fully addressed. The effect of single salt (400 mM NaCl) and heat (control at 26/22 C, supra optimal temperatures at 35/22 C and 45/22 C day/night) conditions on C. glauca branchlets was characterised at the physiological level, and stress-induced metabolite changes were characterised by mass spectrometry-based metabolomics. C. glauca could withstand single salt and heat conditions. However, the harshest stress condition (400 mM NaCl, 45 C) revealed photosynthetic impairments due to mesophyll and membrane permeability limitations as well as major stress-specific differential responses in C and N metabolism. The increased activity of enzymatic ROS scavengers was, however, revealed to be sufficient to control the plant oxidative status. Although C. glauca could tolerate single salt and heat stresses, their negative interaction enhanced the effects of salt stress. Results demonstrated that C. glauca responses to combined salt-heat stress could be explained as a sum of the responses from each single applied stressinfo:eu-repo/semantics/publishedVersio

Seagrasses benefit from mild anthropogenic nutrient additions

Seagrasses are declining globally, in large part due to increased anthropogenic coastal nutrient loads that enhance smothering by macroalgae, attenuate light, and are toxic when in excessive concentrations of inorganic nitrogen and phosphorus. However, as sanitation is improved many seagrass meadows have been observed to recover, with a few studies suggesting that they may even benefit from mild anthropogenic nutrient additions. Monitoring seagrass demography and health has faced difficulties in establishing the adequate variables and metrics. Such uncertainty in the methods has caused uncertainty of the significance of results presented and compromised extrapolations to other seasons, areas, or species. One solution has come from within the plant self-thinning theories. During the 1980s, an interspecific boundary line (IBL) was determined as the upper limit of the combination of plant density and above-ground biomass for any stand on Earth, setting their maximum possible efficiency in space occupation. Recently, two meta-analyses to determine specific IBLs for algae and for seagrasses have been performed. The recently updated seagrass dataset comprises 5,052 observations from 78 studies on 18 species. These IBLs opened new perspectives for monitoring: the observed distance of a stand to the respective IBL (i.e., each stand's relative efficiency of space occupation) was demonstrated to be a valuable indicator of a population's health. Thus, this metric can be used to determine the impact of nutrients and pollutants on algae and seagrass populations. Furthermore, because the IBLs are common to all species, they may be used to compare all species from any location worldwide. This novel approach showed that Halodule wrightii, Halodule beaudettei, Halophila baillonii, Zostera marina, and Zostera noltei meadows benefit from anthropogenic additions of nitrogen and phosphorus, as long as these additions are moderate. In fact, the healthier Z. noltei meadows in Portugal (and among the healthiest meadows worldwide) were the ones exposed to effluents from wastewater treatment plants (WWTP) and a food factory. We conclude that those effluents are providing water with enough quality and that their optimal management should coordinate the technological solutions of the WWTP with the natural potential of seagrass meadows as water purifiers and biomass producers.info:eu-repo/semantics/publishedVersio

An Efficient Method for Genomic DNA Extraction from Different Molluscs Species

The selection of a DNA extraction method is a critical step when subsequent analysis depends on the DNA quality and quantity. Unlike mammals, for which several capable DNA extraction methods have been developed, for molluscs the availability of optimized genomic DNA extraction protocols is clearly insufficient. Several aspects such as animal physiology, the type (e.g., adductor muscle or gills) or quantity of tissue, can explain the lack of efficiency (quality and yield) in molluscs genomic DNA extraction procedure. In an attempt to overcome these aspects, this work describes an efficient method for molluscs genomic DNA extraction that was tested in several species from different orders: Veneridae, Ostreidae, Anomiidae, Cardiidae (Bivalvia) and Muricidae (Gastropoda), with different weight sample tissues. The isolated DNA was of high molecular weight with high yield and purity, even with reduced quantities of tissue. Moreover, the genomic DNA isolated, demonstrated to be suitable for several downstream molecular techniques, such as PCR sequencing among others