Scales of the magnetic fields in the quiet Sun

Context: The presence of a turbulent magnetic field in the quiet Sun has been unveiled observationally using different techniques. The magnetic field is quasi-isotropic and has field strengths weaker than 100G. It is pervasive and may host a local dynamo. Aims: We aim to determine the length scale of the turbulent magnetic field in the quiet Sun. Methods: The Stokes V area asymmetry is sensitive to minute variations in the magnetic topology along the line of sight. Using data provided by Hinode-SOT/SP instrument, we performed a statistical study of this quantity.We classified the different magnetic regimes and infer properties of the turbulent magnetic regime. In particular we measured the correlation length associated to these fields for the first time. Results: The histograms of Stokes V area asymmetries reveal three different regimes: one organized, quasi-vertical and strong field (flux tubes or other structures of the like); a strongly asymmetric group of profiles found around field concentrations; and a turbulent isotropic field. For the last, we confirm its isotropy and measure correlation lengths from hundreds of kilometers down to 10km, at which point we lost sensitivity. A crude attempt to measure the power spectra of these turbulent fields is made. Conclusions: In addition to confirming the existence of a turbulent field in the quiet Sun, we give further prove of its isotropy.We also measure correlation lengths down to 10km. The combined results show magnetic fields with a large span of length scales, as expected from a turbulent cascade.Comment: 11 pages, 6 figures. Accepted for publication in A&

Evaluación multidisciplinar 3D de una estructura kárstica asociada a colapso y subsidencia (Cuenca del Ebro)

La propagación de cavidades de disolución localizadas por debajo de series aluviales genera una serie de evidencias cuya representación superficial, en ocasiones, puede no ser indicativa de su extensión real en profundidad. La propagación de cavidades a través de medios heterogéneos, en los que pueden existir niveles cementados, puede producir cambios en la progresión de dichas cavidades y la identificación en superficie de grietas, colapsos, o zonas de subsidencia que pueden involucrar decenas de miles de metros cúbicos de material inestable. Cualquier tipo de evaluación de soluciones mitigadoras en estos contextos debe considerar la amplitud de estos volúmenes y el origen del proceso con independencia de la actividad registrada en superficie. En este trabajo se aborda un estudio integrado con el objetivo de determinar la estructura de un sector con evidencias de actividad kárstica superficial y evaluar su extensión y desarrollo tridimensional integrando el análisis geomorfológico, de inspección de campo, geofísica (GPR) y sondeos. The propagation of solution cavities located below alluvial deposits produce surficial evidences that, in some cases, cannot be representative of their actual extension at depth. Cavity propagation through heterogeneous media, for example with interbedded cemented levels, can produce changes in the propagation of deformation producing the identification of cracks, collapses or subsidence zones at the surface. These processes can involve thousands of cubic meters of unstable materials. Any evaluation of mitigation tasks, in this context, needs to consider: i) the amplitude of the affected volumes and ii) the in depth origin with independence of the surficial recorded activity In this work an integrated analysis is developed to evaluate the size and 3D structure of a sector with surficial evidences of karstic activity integrating geomorphological analysis, field inspection, geophysics (GPR) and boreholes

Recent Advances in Chromospheric and Coronal Polarization Diagnostics

I review some recent advances in methods to diagnose polarized radiation with which we may hope to explore the magnetism of the solar chromosphere and corona. These methods are based on the remarkable signatures that the radiatively induced quantum coherences produce in the emergent spectral line polarization and on the joint action of the Hanle and Zeeman effects. Some applications to spicules, prominences, active region filaments, emerging flux regions and the quiet chromosphere are discussed.Comment: Review paper to appear in "Magnetic Coupling between the Interior and the Atmosphere of the Sun", eds. S. S. Hasan and R. J. Rutten, Astrophysics and Space Science Proceedings, Springer-Verlag, 200

Anomalous circular polarization profiles in the He I 1083.0 nm multiplet from solar spicules

We report Stokes vector observations of solar spicules and a prominence in the He I 1083 nm multiplet carried out with the Tenerife Infrared Polarimeter. The observations show linear polarization profiles that are produced by scattering processes in the presence of a magnetic field. After a careful data reduction, we demonstrate the existence of extremely asymmetric Stokes V profiles in the spicular material that we are able to model with two magnetic components along the line of sight, and under the presence of atomic orientation in the energy levels that give rise to the multiplet. We discuss some possible scenarios that can generate the atomic orientation in spicules. We stress the importance of spectropolarimetric observations across the limb to distinguish such signals from observational artifacts.Comment: accepted for publication in Ap

Nuclear receptor NR5A2 and bone: gene expression and association with bone mineral density

ObjectiveThere is growing evidence for a link between energy and bone metabolism. The nuclear receptor subfamily 5 member A2 (NR5A2) is involved in lipid metabolism and modulates the expression of estrogen-related genes in some tissues. The objective of this study was to explore the influence of NR5A2 on bone cells and to determine whether its allelic variations are associated with bone mineral density (BMD).DesignAnalyses of gene expression by quantitative PCR and inhibition of NR5A2 expression by siRNAs were used to explore the effects of NR5A2 in osteoblasts. Femoral neck BMD and 30 single nucleotide polymorphisms (SNPs) were first analyzed in 935 postmenopausal women and the association of NR5A2 genetic variants with BMD was explored in other 1284 women in replication cohorts.ResultsNR5A2 was highly expressed in bone. The inhibition of NR5A2 confirmed that it modulates the expression of osteocalcin, osteoprotegerin, and podoplanin in osteoblasts. Two SNPs were associated with BMD in the Spanish discovery cohort (rs6663479, P=0.0014, and rs2816948, P=0.0012). A similar trend was observed in another Spanish cohort, with statistically significant differences across genotypes in the combined analysis (P=0.03). However, the association in a cohort from the United States was rather weak. Electrophoretic mobility assays and studies with luciferase reporter vectors confirmed the existence of differences in the binding of nuclear proteins and the transcriptional activity of rs2816948 alleles.ConclusionsNR5A2 modulates gene expression in osteoblasts and some allelic variants are associated with bone mass in Spanish postmenopausal women

Clinical Characteristics and Long-term outcomes of patients undergoing combined heart-kidney transplantation: a single-center experience

[Abstract] Background. The purpose of the study was to describe clinical characteristics and long-term survival of patients undergoing combined heart-kidney transplant in a single center. Methods. We conducted a retrospective analysis of 22 consecutive patients who underwent combined heart-kidney transplant at our institution between 1995 and 2013. Long-term outcomes were analyzed by means of the Kaplan-Meier method. Results. Four patients underwent re-do transplant (2 cardiac re-transplants, 1 kidney re-transplant, and 1 combined heart-kidney re-transplant). Most frequent underlying cardiac conditions were coronary artery disease (54%), dilated cardiomyopathy (23%), and chronic rejection of a previous heart graft (18%). Known causes of chronic renal dysfunction were nephroangioesclerosis (23%), drug-related toxicity (14%), and Wegener granulomatosis (5%). Non-specified chronic renal dysfunction was present in 50% patients. In-hospital postoperative mortality rate was 5 of 22 (23%). Causes of early death were directly related to kidney transplant surgery in 4 of 5 (80%) patients. Among the remaining 17 patients who surmounted the postoperative period, long-term survival rates 1 year, 5 years, and 10 years after HKT were 88%, 82%, and 65%, respectively. Over a mean follow-up of 6.7 ± 6.4 years, cumulative incidences of cytomegalovirus infection, coronary allograft vasculopathy, malignancy, and acute cardiac graft rejection were 41%, 6%, 24%, and 41%, respectively. There was no episode of acute renal graft rejection. At the end of follow-up, all survivors (n = 11) were in functional New York Heart Association class I. Mean creatinine serum level was 1.68 mg/dL. Conclusions. In our experience, combined heart-kidney transplant is a feasible therapeutic option that yielded favorable long-term outcomes, with a low cumulative incidence of cardiac graft dysfunction. These results were obtained at the expense of a significant risk of early postoperative mortality, which was mainly related to complications of kidney transplant surgery