1,542 research outputs found
The CARMENES search for exoplanets around M dwarfs The warm super-Earths in twin orbits around the mid-type M dwarfs Ross 1020 (GJ 3779) and LP 819-052 (GJ 1265)
We announce the discovery of two planetary companions orbiting around the low-mass stars Ross 1020 (GJ 3779, M4.0V) and LP 819- 052 (GJ 1265, M4.5V). The discovery is based on the analysis of CARMENES radial velocity (RV) observations in the visual channel as part of its survey for exoplanets around M dwarfs. In the case of GJ 1265, CARMENES observations were complemented with publicly available Doppler measurements from HARPS. The datasets reveal two planetary companions, one for each star, that share very similar properties: minimum masses of 8.0 ± 0.5 M⊕ and 7.4 ± 0.5 M⊕ in low-eccentricity orbits with periods of 3.023 ± 0.001 d and 3.651±0.001 d for GJ 3779 b and GJ 1265 b, respectively. The periodic signals around 3 d found in the RV data have no counterpart in any spectral activity indicator. Furthermore, we collected available photometric data for the two host stars, which confirm that the additional Doppler variations found at periods of approximately 95 d can be attributed to the rotation of the stars. The addition of these planets to a mass-period diagram of known planets around M dwarfs suggests a bimodal distribution with a lack of short-period low-mass planets in the range of 2–5 M⊕. It also indicates that super-Earths (>5 M⊕) currently detected by RV and transit techniques around M stars are usually found in systems dominated by a single planet
Valoración del consumo de agua y presencia de la fauna silvestre en bebederos artificiales en un entorno mediterráneo continental seco
Dynamic screening of a localized hole during photoemission from a metal cluster
Recent advances in attosecond spectroscopy techniques have fueled the
interest in the theoretical description of electronic processes taking place in
the subfemtosecond time scale. Here we study the coupled dynamic screening of a
localized hole and a photoelectron emitted from a metal cluster using a
semi-classical model. Electron density dynamics in the cluster is calculated
with Time-Dependent Density Functional Theory and the motion of the
photoemitted electron is described classically. We show that the dynamic
screening of the hole by the cluster electrons affects the motion of the
photoemitted electron. At the very beginning of its trajectory, the
photoemitted electron interacts with the cluster electrons that pile up to
screen the hole. Within our model, this gives rise to a significant reduction
of the energy lost by the photoelectron. Thus, this is a velocity dependent
effect that should be accounted for when calculating the average losses
suffered by photoemitted electrons in metals.Comment: 15 pages, 5 figure
The CARMENES search for exoplanets around M dwarfs: Nine new double-line spectroscopic binary stars
Context. The CARMENES spectrograph is surveying ~300 M dwarf stars in search
for exoplanets. Among the target stars, spectroscopic binary systems have been
discovered, which can be used to measure fundamental properties of stars. Aims.
Using spectroscopic observations, we determine the orbital and physical
properties of nine new double-line spectroscopic binary systems by analysing
their radial velocity curves. Methods. We use two-dimensional cross-correlation
techniques to derive the radial velocities of the targets, which are then
employed to determine the orbital properties. Photometric data from the
literature are also analysed to search for possible eclipses and to measure
stellar variability, which can yield rotation periods. Results. Out of the 342
stars selected for the CARMENES survey, 9 have been found to be double-line
spectroscopic binaries, with periods ranging from 1.13 to ~8000 days and orbits
with eccentricities up to 0.54. We provide empirical orbital properties and
minimum masses for the sample of spectroscopic binaries. Absolute masses are
also estimated from mass-luminosity calibrations, ranging between ~0.1 and ~0.6
Msol . Conclusions. These new binary systems increase the number of double-line
M dwarf binary systems with known orbital parameters by 15%, and they have
lower mass ratios on average.Comment: Accepted for publication in A&A. 17 pages, 4 figure
Alberta Stroke Program Early CT Score applied to CT angiography source images is a strong predictor of futile recanalization in acute ischemic stroke
The final publication is available at Springer via http://dx.doi.org/10.1007/s00234-016-1652-7Introduction Reliable predictors of poor clinical outcome despite successful revascularization might help select patients with acute ischemic stroke for thrombectomy. We sought to determine whether baseline Alberta Stroke Program Early CT Score (ASPECTS) applied to CT angiography source images (CTA-SI) is useful in predicting futile recanalization. Methods Data are from the FUN-TPA study registry (ClinicalTrials.gov; NCT02164357) including patients with acute ischemic stroke due to proximal arterial occlusion in anterior circulation, undergoing reperfusion therapies. Baseline non-contrast CT and CTA-SI-ASPECTS, timelapse to image acquisition, occurrence, and timing of recanalization were recorded. Outcome measures were NIHSS at 24 h, symptomatic intracranial hemorrhage, modified Rankin scale score, and mortality at 90 days. Futile recanalization was defined when successful recanalization was associated with poor functional outcome (death or disability).
Results Included were 110 patients, baseline NIHSS 17 (IQR 12; 20), treated with intravenous thrombolysis (IVT; 45 %), primary mechanical thrombectomy (MT; 16 %), or combined IVT+MT (39 %). Recanalization rate was 71 %,
median delay of 287 min (225; 357). Recanalization was futile in 28 % of cases. In an adjusted model, baseline CTA-SI-ASPECTS was inversely related to the odds of futile recanalization (OR 0.5; 95 % CI 0.3–0.7), whereas NCCT-ASPECTS was not (OR 0.8; 95 % CI 0.5–1.2). A score ≤5 in CTA-SIASPECTS was the best cut-off to predict futile recanalization (sensitivity 35 %; specificity 97 %; positive predictive value 86 %; negative predictive value 77 %).
Conclusions CTA-SI-ASPECTS strongly predicts futile recanalization and could be a valuable tool for treatment decisions regarding the indication of revascularization therapie
Más allá de la hiperglucemia: la variabilidad glucémica como factor pronóstico en el infarto cerebral agudo
Glycaemic variability (GV) refers to variations in blood glucose levels, and may affect stroke outcomes. This study aims to assess the effect of GV on acute ischaemic stroke progression. We performed an exploratory analysis of the multicentre, prospective, observational GLIAS-II study. Capillary glucose levels were measured every 4 hours during the first 48 hours after stroke, and GV was defined as the standard deviation of the mean glucose values. The primary outcomes were mortality and death or dependency at 3 months. Secondary outcomes were in-hospital complications, stroke recurrence, and the impact of the route of insulin administration on GV. Results: A total of 213 patients were included. Higher GV values were observed in patients who died (n = 16; 7.8%; 30.9 mg/dL vs 23.3 mg/dL; p = 0.05). In a logistic regression analysis adjusted for age and comorbidity, both GV (OR = 1.03; 95% CI, 1.003-1.06; p = 0.03) and stroke severity (OR = 1.12; 95% CI, 1.04-1.2; p = 0.004) were independently associated with mortality at 3 months. No association was found between GV and the other outcomes. Patients receiving subcutaneous insulin showed higher GV than those treated with intravenous insulin (38.95 mg/dL vs 21.34 mg/dL; p < 0.001). Conclusions: High GV values during the first 48 hours after ischaemic stroke were independently associated with mortality. Subcutaneous insulin may be associated with higher VG levels than intravenous administration.La variabilidad glucémica (VG) hace referencia a las oscilaciones en los niveles de glucosa en sangre y podría influir en el pronóstico del ictus. Analizar el efecto de la VG en la evolución del infarto cerebral agudo (IC). Análisis exploratorio del estudio GLIAS-II (multicéntrico, prospectivo y observacional). Se midieron los niveles de glucemia capilar cada cuatro horas durante las primeras 48 horas y la VG se definió como la desviación estándar de los valores medios. Variables principales: mortalidad y muerte o dependencia a los tres meses. Variables secundarias: porcentaje de complicaciones intrahospitalarias y de recurrencia de ictus, e influencia de la vía de administración de insulina sobre la VG.
Se incluyeron 213 pacientes. Los pacientes que fallecieron (N = 16;7,8%) presentaron mayores valores de VG (30,9 mg/dL vs. 23,3 mg/dL; p = 0,05). En el análisis de regresión logística ajustado por edad y comorbilidad, tanto la VG (OR = 1,03; IC del 95%: 1,003-1,06: p = 0,03) como la gravedad del IC (OR = 1,12; IC del 95%: 1,04-1,2; p = 0,004) se asociaron de forma independiente con la mortalidad a los tres meses. No se encontró asociación entre la VG y las demás variables de estudio. Los pacientes que recibieron tratamiento con insulina subcutánea mostraron una mayor VG que los tratados con insulina intravenosa (38,9 mg/dL vs. 21,3 mg/dL; p < 0,001).
Conclusiones: Valores elevados de VG durante las primeras 48 horas tras el IC se asociaron de forma independiente con la mortalidad. La administración subcutánea de insulina podría condicionar una mayor VG que la vía intravenosaFinanciado por el Instituto de Salud Carlos III (ISCIII) y el FEDER (PI 09/01781). Promovido por el Proyecto Ictus del Grupo de Estudio de Enfermedades Cerebrovasculares de la Sociedad Espanola ˜ de Neurología, y las Redes de Investigación temática RETICS INVICTUS e INVICTUS Plus (RD12/0014/0006, RD16/0019/0005
Genome-wide profiling of methylation identifies novel targets with aberrant hyper-methylation and reduced expression in low-risk myelodysplastic syndromes
Gene expression profiling signatures may be used to classify the subtypes of Myelodysplastic syndrome (MDS) patients. However, there are few reports on the global methylation status in MDS. The integration of genome-wide epigenetic regulatory marks with gene expression levels would provide additional information regarding the biological differences between MDS and healthy controls. Gene expression and methylation status were measured using high-density microarrays. A total of 552 differentially methylated CpG loci were identified as being present in low-risk MDS; hypermethylated genes were more frequent than hypomethylated genes. In addition, mRNA expression profiling identified 1005 genes that significantly differed between low-risk MDS and the control group. Integrative analysis of the epigenetic and expression profiles revealed that 66.7% of the hypermethylated genes were underexpressed in low-risk MDS cases. Gene network analysis revealed molecular mechanisms associated with the low-risk MDS group, including altered apoptosis pathways. The two key apoptotic genes BCL2 and ETS1 were identified as silenced genes. In addition, the immune response and micro RNA biogenesis were affected by the hypermethylation and underexpression of IL27RA and DICER1. Our integrative analysis revealed that aberrant epigenetic regulation is a hallmark of low-risk MDS patients and could have a central role in these diseases. © 2013 Macmillan Publishers Limited All rights reserved
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