12,778 research outputs found
The Earth Mantle-Core Effect in Matter-Induced Asymmetries for Atmospheric Neutrino Oscillations
Earth medium effects in the three-neutrino oscillations of atmospheric
neutrinos are observable under appropriate conditions. This paper generalizes
the study of the medium effects and the possibility of their observation in the
atmospheric neutrino oscillations from the case of neutrinos traversing only
the Earth mantle, where the density is essentially constant, to the case of
atmospheric neutrinos crossing also the Earth core. In the latter case new
resonance-like effects become apparent. We calculate the CPT-odd asymmetry for
the survival probability of muon neutrinos and the observable muon-charge
asymmetry, taking into account the different atmospheric neutrino fluxes, and
show the dependence of these asymmetries on the sign of
and on the magnitude of the mixing angle . A magnetized detector
with a sufficiently good neutrino momentum resolution is required for the
observation of the muon-charge asymmetry generated by the Earth mantle-core
effect.Comment: 14 pages, 5 figure
2MASS J154043.42-510135.7: a new addition to the 5 pc population
The aim of the project is to find the stars nearest to the Sun and to
contribute to the completion of the stellar and substellar census of the solar
neighbourhood. We identified a new late-M dwarf within 5 pc, looking for high
proper motion sources in the 2MASS-WISE cross-match. We collected astrometric
and photometric data available from public large-scale surveys. We complemented
this information with low-resolution optical and near-infrared spectroscopy
with instrumentation on the ESO NTT to confirm the nature of our candidate. We
also present a high-quality medium-resolution VLT/X-shooter spectrum covering
the 400 to 2500 nm wavelength range. We classify this new neighbour as an
M7.00.5 dwarf using spectral templates from the Sloan Digital Sky Survey
and spectral indices. Lithium absorption at 670.8 nm is not detected in the
X-shooter spectrum, indicating that the M7 dwarf is older than 600 Myr and more
massive than 0.06 M. We also derive a trigonometric distance of 4.4
pc, in agreement with the spectroscopic distance estimate, making
2MASS\,J154043.42510135.7 the nearest M7 dwarf to the Sun. This
trigonometric distance is somewhat closer than the 6 pc distance reported
by the ALLWISE team, who independently identified this object recently. This
discovery represents an increase of 25\% in the number of M7--M8 dwarfs already
known at distances closer than 8\,pc from our Sun. We derive a density of
\,=\,1.90.910\,pc for M7 dwarfs in the 8 pc
volume, a value similar to those quoted in the literature. This new ultracool
dwarf is among the 50 nearest systems to the Sun, demonstrating that our
current knowledge of the stellar census within the 5 pc sample remains
incomplete. 2M1540 represents a unique opportunity to search for extrasolar
planets around ultracool dwarfs due to its proximity and brightness.Comment: 8 pages, 5 figures. Acepted in Astronomy & Astrophysics (15/05/2005
Temporal analysis of natural radionuclides deposition at Málaga(2005-2016)
Atmospheric deposition of radionuclides has been investigated in many studies from the aspects of both
radiation protection and geochemistry. The present study, carried out in the city of Málaga, in the southeast
of Spain, focuses on the assessment of the bulk depositional fluxes of three natural radionuclides: 7Be
(cosmogenic origin), and 210Pb and 40K (crustal origin). These three radionuclides are useful markers of
particles arising from their respective sources. To obtain fundamental information of atmospheric
transportation, sedimentation and geological process of particulate matter, a long-term monitoring of
atmospheric deposition has been carried out in Málaga from January 2005-December 2016. Samples of
bulk deposition were collected on a monthly basis on a stainless steel tray from January 2005 to
December 2016. Afterwards, a volume of 6 L of the bulk deposition was reduced via evaporation to 1 L
approximately and transferred to a Marinelli geometry container for gamma counting. Additionally,
aerosols samples were collected weekly in cellulose membrane filters of 0.8μm pore size and 47mm
diameter with an air sampler lodged in an all-weather sampling station, situated on the roof near the bulk
rain collector. Gamma counting of the aerosols and bulk deposition samples was performed using an
intrinsic germanium coaxial detector, Re-Ge-type (CANBERRA). This study describes the results and
then discusses characteristics of atmospheric deposition of mentioned radionuclides with respect to
seasonal variations and dependency on controlling factors. The depositional fluxes of all radionuclides
showed a clear seasonal trend with summer minimum and high values in wintertime
Binary frequency of planet-host stars at wide separations: A new brown dwarf companion to a planet-host star
The aim of the project is to improve our knowledge on the multiplicity of
planet-host stars at wide physical separations.
We cross-matched approximately 6200 square degree area of the Southern sky
imaged by the Visible Infrared Survey Telescope for Astronomy (VISTA)
Hemisphere Survey (VHS) with the Two Micron All Sky Survey (2MASS) to look for
wide common proper motion companions to known planet-host stars. We
complemented our astrometric search with photometric criteria.
We confirmed spectroscopically the co-moving nature of seven sources out of
16 companion candidates and discarded eight, while the remaining one stays as a
candidate. Among these new wide companions to planet-host stars, we discovered
a T4.5 dwarf companion at 6.3 arcmin (~9000 au) from HIP70849, a K7V star which
hosts a 9 Jupiter mass planet with an eccentric orbit. We also report two new
stellar M dwarf companions to one G and one metal-rich K star. We infer stellar
and substellar binary frequencies for our complete sample of 37 targets of
5.4+/-3.8% and 2.7+/-2.7% (1 sigma confidence level), respectively, for
projected physical separations larger than ~60-160 au assuming the range of
distances of planet-host stars (24-75 pc). These values are comparable to the
frequencies of non planet-host stars. We find that the period-eccentricity
trend holds with a lack of multiple systems with planets at large
eccentricities (e > 0.2) for periods less than 40 days. However, the lack of
planets more massive than 2.5 Jupiter masses and short periods (<40 days)
orbiting single stars is not so obvious due to recent discoveries by
ground-based transit surveys and space missions.Comment: Accepted for publication in A&A, 13 pages, 5 figures, 3 tables,
optical spectra will be available at CDS Strasbour
Clinical and molecular characterization of a cardiac ryanodine receptor founder mutation causing catecholaminergic polymorphic ventricular tachycardia
Background Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a difficult-to-diagnose cause of sudden cardiac death (SCD). We identified a family of 1400 individuals with multiple cases of CPVT, including 36 SCDs during youth. Objectives We sought to identify the genetic cause of CPVT in this family, to preventively treat and clinically characterize the mutation-positive individuals, and to functionally characterize the pathogenic mechanisms of the mutation. Methods Genetic testing was performed for 1404 relatives. Mutation-positive individuals were preventively treated with β-blockers and clinically characterized with a serial exercise treadmill test (ETT) and Holter monitoring. In vitro functional studies included caffeine sensitivity and store overload–induced calcium release activity of the mutant channel in HEK293 cells. Results We identified the p.G357S_RyR2 mutation, in the cardiac ryanodine receptor, in 179 family members and in 6 SCD cases. No SCD was observed among treated mutation-positive individuals over a median follow-up of 37 months; however, 3 relatives who had refused genetic testing (confirmed mutation-positive individuals) experienced SCD. Holter monitoring did not provide relevant information for CPVT diagnosis. One single ETT was unable to detect complex cardiac arrhythmias in 72% of mutation-positive individuals, though the serial ETT improved the accuracy. Functional studies showed that the G357S mutation increased caffeine sensitivity and store overload–induced calcium release activity under conditions that mimic catecholaminergic stress. Conclusion Our study supports the use of genetic testing to identify individuals at risk of SCD to undertake prophylactic interventions. We also show that the pathogenic mechanisms of p.G357S_RyR2 appear to depend on β-adrenergic stimulation
Hysteroscopic Management of an Interstitial Ectopic Pregnancy
We report a case of an interstitial ectopic pregnancy successfully managed by hysteroscopy. We highlight the benefits of using hysteroscopy, a non-invasive procedure, to preserve fertility
Macrophage Targeting pH Responsive Polymersomes for Glucocorticoid Therapy
Glucocorticoid (GC) drugs are the cornerstone therapy used in the treatment of inflammatory diseases. Here, we report pH responsive poly(2-methacryloyloxyethyl phosphorylcholine)–poly(2-(diisopropylamino)ethyl methacrylate) (PMPC–PDPA) polymersomes as a suitable nanoscopic carrier to precisely and controllably deliver GCs within inflamed target cells. The in vitro cellular studies revealed that polymersomes ensure the stability, selectivity and bioavailability of the loaded drug within macrophages. At molecular level, we tested key inflammation-related markers, such as the nuclear factor-κB, tumour necrosis factor-α, interleukin-1β, and interleukin-6. With this, we demonstrated that pH responsive polymersomes are able to enhance the anti-inflammatory effect of loaded GC drug. Overall, we prove the potential of PMPC–PDPA polymersomes to efficiently promote the inflammation shutdown, while reducing the well-known therapeutic limitations in GC-based therapy
Diagnóstico y medidas de remediación por altas concentraciones de radón en vivienda unifamiliar en el sur de España
Desde hace años existe una importante preocupación e interés en la comunidad científica por la exposición a altos niveles de radon en el interior de la viviendas, centros de trabajo y colegios. Esta preocupación se está extendiendo al conjunto de la población y son numerosas las referencias en artículos de prensa y medios de comunicación a este gas noble. Es bien sabido que las personas que inhalan altas concentraciones de radón tienen un riesgo mayor de padecer cáncer de pulmón, que es inducido por los descendientes del gas inhalado. En este trabajo presentamos los datos más relevantes obtenidos en una vivienda unifamiliar en la que los propietarios sospechaban de estar sometidos a altas concentraciones de radon. Para realizar el estudio utilizamos sistemas activos, concretamente 6 dispositivos con cámara de difusión con diodo de silicio, modelo Alpha E de Saphimo y un equipo AlphaGuard 2000 Pro, y sistemas pasivos mediante cartuchos de carbón activo para medidas en equipo de espectrometría gamma. Se trata de una vivienda de 550 m2 distribuidos en dos módulos con dos alturas y sótano acondicionado como vivienda del servicio. Tras una evaluación inicial en toda la vivienda, detectamos altos niveles de radon en tres estancias de la casa, registrando valores medios >6000 Bqm-3 con un valor máximo de 25350 Bqm-3. Se realizaron medidas correctoras mediante el uso de materiales impermeabilizantes y sistemas de extracción forzada en la zona no habitada del sótano consiguiendo disminuir los niveles de radon por debajo de los 100 Bqm-3 como valor medio
The Pic Protease of Enteroaggregative \u3cem\u3eEscherichia coli\u3c/em\u3e Promotes Intestinal Colonization and Growth in the Presence of Mucin
Enteroaggregative Escherichia coli (EAEC) is increasingly being recognized as a cause of diarrheal disease in diverse populations. No small animal model is currently available to study this pathogen. We report here that conventional mice orally inoculated with prototype EAEC strain 042 generally became colonized, though the abundance of organisms cultured from their stool varied substantially among individual animals. In contrast, mice whose water contained 5 g/liter streptomycin consistently became colonized at high levels (ca. 108 CFU/g of stool). Neither conventional nor streptomycin-treated mice developed clinical signs or histopathologic abnormalities. Using specific mutants in competition with the wild-type strain, we evaluated the contribution of several putative EAEC virulence factors to colonization of streptomycin-treated mice. Our data suggest that the dispersin surface protein and Pic, a serine protease autotransporter secreted by EAEC and Shigella flexneri, promote colonization of the mouse. In contrast, we found no role for the aggregative adherence fimbriae, the transcriptional activator AggR, or the surface factor termed Air (enteroaggregative immunoglobulin repeat protein). To study Pic further, we constructed a single nucleotide mutation in strain 042 which altered only the Pic catalytic serine (strain 042PicS258A). Fractionation of the tissue at 24 h and 3 days demonstrated an approximate 3-log10 difference between 042 and 042PicS258A in the lumen and mucus layer and adherent to tissue. Strains 042 and 042PicS258A adhered similarly to mouse tissue ex vivo. While no growth differences were observed in a continuous-flow anaerobic intestinal simulator system, the wild-type strain exhibited a growth advantage over 042PicS258A in a culture of cecal mucus and in cecal contents in vitro; this difference was manifest only after 6 h of growth. Moreover, enhanced growth of the wild type was observed in comparison with that of the mutant in minimal medium containing mucin but not in the absence of mucin. The data suggest a novel metabolic role for the Pic mucinase in EAEC colonization
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