154 research outputs found
Anisotropic Dirac cones in monatomic hexagonal lattices
In the last few years, the fascinating properties of graphene have been
thoroughly investigated. The existence of Dirac cones is the most important
characteristic of the electronic band-structure of graphene. In this
theoretical paper, hexagonal monolayers of silicon (h-Si) and germanium (h-Ge)
are examined using density functional theory, within the generalized gradient
approximation. Our numerical results indicate that both h-Si and h-Ge are
chemically stable. The lattice parameters, electronic dispersion relations and
densities of states for these systems are reported. The electronic dispersion
relations display Dirac cones with the symmetry of an equilateral triangle (the
group D) in the vicinity of the K points. Hence, the Fermi velocity depends
on the wave vector direction around points. Fermi velocities for holes and
electrons are significantly different. The maximum and minimum Fermi velocities
are also reported.Comment: 7 pages, 9 figures. Accepted for publication in The European Physical
Journal B (EPJB
Epigenetic control of the EWS-FLI1 promoter in Ewing's sarcoma
Q2Q1Ewing sarcoma (ES) is a primary bone marrow tumor that very rarely develops in extra-osseous tissues, such as lung. The hallmark of ES tumors is a translocation between chromosomes 11 and 22, resulting in a fusion protein, commonly referred to as EWS-FLI1. The epigenetic profile (histone acetylation and methylation enrichment of the promoter region) that may regulate the expression of the aberrant transcription factor EWS-FLI1, remains poorly studied and understood. Knowledge of epigenetic patterns associated with covalent histone modification and expression of enzymes associated with this process, can contribute to the understanding of the molecular basis of the disease, as well as to the identification of possible molecular targets involved in expression of the EWS-FLI1 gene, so that therapeutic strategies may be improved in the future. In the present study, the transcriptional activation and repression of the EWS-FLI1 fusion gene in ES was accompanied by selective deposition of histone markers on its promoter. The EWS-FLI1 fusion gene was evaluated in two patients with ES using conventional cytogenetic, fluorescence in situ hybridization and nested PCR assays, which revealed that the aberrant expression of the EWS-FLI1 gene is accompanied by enrichment of H3K4Me3, H3K9ac and H3K27ac at the promoter region.N/
Cytotoxicity effects of metal oxide nanoparticles in human tumor cell lines
Metallic and metal oxide nanoparticles (Nps) have a wide range of applications in various settings including household, cosmetics and chemical industries, as well as for coatings. Nevertheless, an in-depth study of the potential toxic effects of these Nps is still needed, in order to fulfill the mandatory requirement of ensuring the safety of workers, patients and the general public. In this study, Quick Cell colorimetric assays were used to evaluate the in vitro toxicity of different metal oxide Nps [Fe(II,III)Ox, TiOx, ZnO and CeO2] in several cell lines. The ZnO Nps were found to be highly toxic, with a lethal dose â„100 ÎŒg/ml for all the cell lines studied. Western blot was also used to test the ability of the different Nps to activate the complement pathway. However, no activation of this cascade was observed when the Nps were added. In addition, the aggregation state and charge of the Nps in culture media was studied by dynamic light scattering (DLS) and measurement of zeta potential. Transmission Electron Microscopy was used to analyze Np uptake and localization at the cellular level
Anisotropic Pressures in Very Dense Magnetized Matter
The problem of anisotropic pressures arising as a consequence of the spatial
symmetry breaking introduced by an external magnetic field in quantum systems
is discussed. The role of the conservation of energy and momentum of external
fields as well as of systems providing boundary conditions in quantum
statistics is considered. The vanishing of the average transverse momentum for
an electron-positron system in its Landau ground state is shown, which means
the vanishing of its transverse pressure. The situation for neutron case and
Strange Quark Matter (SQM) in -equilibrium is also briefly discussed.
Thermodynamical relations in external fields as well as the form of the stress
tensor in a quantum relativistic medium are also discussed. The ferromagnetic
symmetry breaking is briefly discussed.Comment: 10 page
How acceptable are antiretrovirals for the prevention of sexually transmitted HIV? A review of research on the acceptability of oral pre-exposure prophylaxis and treatment as prevention
Recent research has demonstrated how antiretrovirals (ARVs) could be effective in the prevention of sexually transmitted HIV. We review research on the acceptability of oral pre-exposure prophylaxis (PrEP) and treatment as prevention (TasP) for HIV prevention amongst potential users. We consider with whom, where and in what context this research has been conducted, how acceptability has been approached, and what research gaps remain. Findings from 33 studies show a lack of TasP research, PrEP studies which have focused largely on men who have sex with men (MSM) in a US context, and varied measures of acceptability. In order to identify when, where and for whom PrEP and TasP would be most appropriate and effective, research is needed in five areas: acceptability of TasP to people living with HIV; motivation for PrEP use and adherence; current perceptions and management of risk; the impact of broader social and structural factors; and consistent definition and operationalisation of acceptability which moves beyond adherence
Long-term surveillance of the feline leukemia virus in the endangered Iberian lynx (Lynx pardinus) in Andalusia, Spain (2008-2021)
Feline leukemia virus (FeLV) infection is considered one of the most serious disease threats for the endangered Iberian lynx (Lynx pardinus) Over 14Â years (2008-2021), we investigated FeLV infection using point-of-care antigen test and quantitative real-time TaqMan qPCR for provirus detection in blood and tissues in lynxes from Andalusia (Southern Spain). A total of 776 samples from 586 individuals were included in this study. The overall prevalence for FeLV antigen in blood/serum samples was 1.4% (5/360) (95% CI: 0.2-2.6), FeLV proviral DNA prevalence in blood samples was 6.2% (31/503) (95% CI: 4.1-8.6), and FeLV proviral DNA in tissues samples was 10.2% (34/333) (95% CI: 7-13.5). From a subset of 129 longitudinally sampled individuals, 9.3% (12/129) PCR-converted during the study period. Our results suggest that FeLV infection in the Andalusian population is enzootic, with circulation of the virus at low levels in almost all the sampling years. Moreover, since only one viremic individual succumbed to the infection, this study suggests that lynxes may therefore control the infection decreasing the possibility of developing a more aggressive outcome. Although our results indicate that the FeLV infection in the Iberian lynx from Andalusia tends to stay within the regressive stage, continuous FeLV surveillance is paramount to predict potential outbreaks and ensure the survival of this population
Deep Echelle Spectrophotometry of S 311, a galactic H II Region Outside the Solar Circle
We present echelle spectrophotometry of the Galactic H II region S 311. The
data have been taken with the Very Large Telescope UVES echelle spectrograph in
the 3100 to 10400 angstroms range. We have measured the intensities of 263
emission lines, 178 are permitted lines of H0, D0 (deuterium), He0, C0, C+, N0,
N+, O0, O+, S+, Si0, Si+, Ar0 and Fe0; some of them are produced by
recombination and others mainly by fluorescence. Physical conditions have been
derived using different continuum and line intensity ratios. We have derived
He+, C++ and O++ ionic abundances from pure recombination lines as well as
abundances from collisionally excited lines for a large number of ions of
different elements. We have obtained consistent estimations of t2 applying
different methods. We have found that the temperature fluctuations paradigm is
consistent with the t2(He I) vs. t2(H I) relation for H II regions, in contrast
with what has been found for planetary nebulae. We report the detection of
deuterium Balmer lines up to D6 in the blue wings of the hydrogen lines, which
excitation mechanism seems to be continuum fluorescence.Comment: 13 pages, 12 tables, 5 figures, accepted for publication in MNRA
Associations between eating speed, diet quality, adiposity, and cardiometabolic risk factors
Objective: To assess the associations between eating speed, adiposity, cardiometabolic risk factors, and diet quality in a cohort of Spanish preschool-children. Study design: A cross-sectional study in 1371 preschool age children (49% girls; mean age, 4.8 ± 1.0 years) from the Childhood Obesity Risk Assessment Longitudinal Study (CORALS) cohort was conducted. After exclusions, 956 participants were included in the analyses. The eating speed was estimated by summing the total minutes used in each of the 3 main meals and then categorized into slow, moderate, or fast. Multiple linear and logistic regression models were fitted to assess the ÎČ-coefficient, or OR and 95% CI, between eating speed and body mass index, waist circumference, fat mass index (FMI), blood pressure, fasting plasma glucose, and lipid profile. Results: Compared with participants in the slow-eating category, those in the fast-eating category had a higher prevalence risk of overweight/obesity (OR, 2.9; 95% CI, 1.8-4.4; P < .01); larger waist circumference (ÎČ, 2.6 cm; 95% CI, 1.5-3.8 cm); and greater FMI (ÎČ, 0.3 kg/m2; 95% CI, 0.1-0.5 kg/m2), systolic blood pressure (ÎČ, 2.8 mmHg; 95% CI, 0.6-4.9 mmHg), and fasting plasma glucose levels (ÎČ, 2.7 mg/dL, 95% CI, 1.2-4.2 mg/dL) but lower adherence to the Mediterranean diet (ÎČ, â0.5 points; 95% CI, â0.9 to â0.1 points). Conclusions: Eating fast is associated with higher adiposity, certain cardiometabolic risk factors, and lower adherence to a Mediterranean diet. Further long-term and interventional studies are warranted to confirm these associations
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