1,243 research outputs found
Search for neutrinos from transient sources with the ANTARES telescope and optical follow-up observations
The ANTARES telescope has the opportunity to detect transient neutrino
sources, such as gamma-ray bursts, core-collapse supernovae, flares of active
nuclei... To enhance the sensitivity to these sources, we have developed a new
detection method based on the optical follow-up of "golden" neutrino events
such as neutrino doublets coincident in time and space or single neutrinos of
very high energy. The ANTARES Collaboration has therefore implemented a very
fast on-line reconstruction with a good angular resolution. These
characteristics allow to trigger an optical telescope network; since February
2009. ANTARES is sending alert trigger one or two times per month to the two 25
cm robotic telescope of TAROT. This follow-up of such special events would not
only give access to the nature of the sources but also improves the sensitivity
for transient neutrino sources.Comment: 3 pages, 3 figures, Proceedings of the 31st ICRC, Lodz, Polan, July
200
Photoionization in the time and frequency domain
Ultrafast processes in matter, such as the electron emission following light
absorption, can now be studied using ultrashort light pulses of attosecond
duration (s) in the extreme ultraviolet spectral range. The lack of
spectral resolution due to the use of short light pulses may raise serious
issues in the interpretation of the experimental results and the comparison
with detailed theoretical calculations. Here, we determine photoionization time
delays in neon atoms over a 40 eV energy range with an interferometric
technique combining high temporal and spectral resolution. We spectrally
disentangle direct ionization from ionization with shake up, where a second
electron is left in an excited state, thus obtaining excellent agreement with
theoretical calculations and thereby solving a puzzle raised by seven-year-old
measurements. Our experimental approach does not have conceptual limits,
allowing us to foresee, with the help of upcoming laser technology, ultra-high
resolution time-frequency studies from the visible to the x-ray range.Comment: 5 pages, 4 figure
CodABC: a computational framework to coestimate recombination, substitution, and molecular adaptation rates by approximate Bayesian computation
The estimation of substitution and recombination rates can provide important insights into the molecular evolution of protein-coding sequences. Here, we present a new computational framework, called CodABC, to jointly estimate recombination, substitution and synonymous and non-synonymous rates from coding data. CodABC uses approximate Bayesian computation (ABC) with and without regression adjustment and implements a variety of codon models, intracodon recombination and longitudinal sampling. CodABC can provide accurate joint parameter estimates from recombining coding sequences, often outperforming maximum likelihood methods based on more approximate models. In addition, CodABC allows for the inclusion of several nuisance parameters such as those representing codon frequencies, transition matrices, heterogeneity across sites or invariable sites. CodABC is freely available from http://code.google.com/p/codabc/, includes a GUI, extensive documentation and ready-touse examples, and can run in parallel on multicore machines.Ministerio de Ciencia e InnovaciĂłn | Ref. JCI-2011-10452Fundação para a CiĂȘncia e a Tecnologia | Ref. EXCL/BIA-ANM/0549/201
MEMPHYS:A large scale water Cerenkov detector at Fr\'ejus
A water \v{C}erenkov detector project, of megaton scale, to be installed in
the Fr\'ejus underground site and dedicated to nucleon decay, neutrinos from
supernovae, solar and atmospheric neutrinos, as well as neutrinos from a
super-beam and/or a beta-beam coming from CERN, is presented and compared with
competitor projects in Japan and in the USA. The performances of the European
project are discussed, including the possibility to measure the mixing angle
and the CP-violating phase .Comment: 1+33 pages, 14 figures, Expression of Interest of MEMPHYS projec
The evolution of the HIV-1 protease folding stability
Financiado para publicaciĂłn en acceso aberto: Universidade de Vigo/CISUGThe evolution of structural proteins is generally constrained by the folding stability. However, little is known about the particular capacity of viral proteins to accommodate mutations that can potentially affect the protein stability and, in general, the evolution of the protein stability over time. As an illustrative model case, here, we investigated the evolution of the stability of the human immunodeficiency virus (HIV-1) protease (PR), which is a common HIV-1 drug target, under diverse evolutionary scenarios that include (1) intra-host virus evolution in a cohort of seventy-five patients sampled over time, (2) intra-host virus evolution sampled before and after specific PR-based treatments, and (3) inter-host evolution considering extant and ancestral (reconstructed) PR sequences from diverse HIV-1 subtypes. We also investigated the specific influence of currently known HIV-1 PR resistance mutations on the PR folding stability. We found that the HIV-1 PR stability fluctuated over time within a constant and wide range in any studied evolutionary scenario, accommodating multiple mutations that partially affected the stability while maintaining activity. We did not identify relationships between change of PR stability and diverse clinical parameters such as viral load, CD4+ T-cell counts, and a surrogate of time from infection. Counterintuitively, we predicted that nearly half of the studied HIV-1 PR resistance mutations do not significantly decrease stability, which, together with compensatory mutations, would allow the protein to adapt without requiring dramatic stability changes. We conclude that the HIV-1 PR presents a wide structural plasticity to acquire molecular adaptations without affecting the overall evolution of stability.Ministerio de EconomĂa y Competitividad | Ref. RYC-2015-18241Xunta de Galicia | Ref. ED431F 2018/08Xunta de Galicia | Ref. ED481A-2020/19
Anticancer and antibacterial potential of robust Ruthenium(II) arene complexes regulated by choice of α-diimine and halide ligands
Several complexes of general formula [Ru(halide)(η6-p-cymene)(α-diimine)]+, in the form of nitrate, triflate and hexafluorophosphate salts, including a newly synthesized iodide compound, were investigated as potential anticancer drugs and bactericides. NMR and UVâVis studies evidenced remarkable stability of the complexes in water and cell culture medium. In general, the complexes displayed strong cytotoxicity against A2780 and A549 cancer cell lines with IC50 values in the low micromolar range, and one complex (RUCYN) emerged as the most promising one, with a significant selectivity compared to the non-cancerous HEK293 cell line. A variable affinity of the complexes for BSA and DNA binding was ascertained by spectrophotometry/fluorimetry, circular dichroism, electrophoresis and viscometry. The performance of RUCYN appears associated to enhanced cell internalization, favored by two cyclohexyl substituents, rather than to specific interaction with the evaluated biomolecules. The chloride/iodide replacement, in one case, led to increased cellular uptake and cytotoxicity at the expense of selectivity, and tuned DNA binding towards intercalation. Complexes with iodide or a valproate bioactive fragment exhibited the best antimicrobial profiles
Natural Formulations Based on Olea europaea L. Fruit Extract for the Topical Treatment of HSV-1 Infections
In the present study, a hydroxytyrosol-rich Olea europaea L. fruit extract (OFE) was added to three thoroughly green formulationsâhydrogel, oleogel, and creamâin order to evaluate their antiviral activity against HSV-1. The extract was characterized by different analytical techniques, i.e., FT-IR, XPS, and TGA. HPLC analyses were carried out to monitor the content and release of hydroxytyrosol in the prepared formulations. The total polyphenol content and antioxidant activity were investigated through FolinâCiocĂąlteuâs reagent, DPPH, and ABTS assays. The ability of the three formulations to convey active principles to the skin was evaluated using a Franz cell, showing that the number of permeated polyphenols in the hydrogel (272.1 ± 1.8 GAE/g) was significantly higher than those in the oleogel and cream (174 ± 10 and 179.6 ± 2 GAE/g, respectively), even if a negligible amount of hydroxytyrosol crossed the membrane for all the formulations. The cell viability assay indicated that the OFE and the three formulations were not toxic to cultured Vero cells. The antiviral activity tests highlighted that the OFE had a strong inhibitory effect against HSV-1 with a 50% inhibitory concentration (IC50) at 25 ”g/mL, interfering directly with the viral particles. Among the three formulations, the hydrogel exhibited the highest antiviral activity also against the acyclovir-resistant strain
A cohesive zone framework for environmentally assisted fatigue
We present a compelling finite element framework to model hydrogen assisted
fatigue by means of a hydrogen- and cycle-dependent cohesive zone formulation.
The model builds upon: (i) appropriate environmental boundary conditions, (ii)
a coupled mechanical and hydrogen diffusion response, driven by chemical
potential gradients, (iii) a mechanical behavior characterized by finite
deformation J2 plasticity, (iv) a phenomenological trapping model, (v) an
irreversible cohesive zone formulation for fatigue, grounded on continuum
damage mechanics, and (vi) a traction-separation law dependent on hydrogen
coverage calculated from first principles. The computations show that the
present scheme appropriately captures the main experimental trends; namely, the
sensitivity of fatigue crack growth rates to the loading frequency and the
environment. The role of yield strength, work hardening, and constraint
conditions in enhancing crack growth rates as a function of the frequency is
thoroughly investigated. The results reveal the need to incorporate additional
sources of stress elevation, such as gradient-enhanced dislocation hardening,
to attain a quantitative agreement with the experiments
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