Superconducting weak links in YBa2Cu3O7-δ an AC magnetic susceptibility study

AC magnetic susceptibility, X' and X'', and ac resistivity, ρ, of two different samples of superconducting YBa2Cu3O7-δ have been measured. The results show a strong non-linear behaviour and are very sensitive to the exciting amplitudes. From the analysis of the data and comparison with appropriate models and other superconducting compounds, evidence for the existence of weak superconducting links is inferred. Finally, the utility of acX measurements for detection of different superconducting phases is made evident. \u

The VVV Survey RR Lyrae Population in the Galactic Center Region

Indexación: Scopus.We gratefully acknowledge the use of data from the ESO Public Survey program ID 179.B-2002 taken with the VISTA telescope, and data products from the Cambridge Astronomical Survey Unit (CASU). Support for the authors is provided by the BASAL Center for Astrophysics and Associated Technologies (CATA) through grant PFB-06, and the Ministry for the Economy, Development, and Tourism, Programa Iniciativa Cientifica Milenio through grant IC120009, awarded to the Millennium Institute of Astrophysics (MAS). D.M. and M.Z. acknowledge support from FONDECYT Regular grants No. 1170121, and 1150345, respectively. P.H. acknowledges financial support from FONDECYT regular grant 1170305. F.G. acknowledge support from CONICYT-PCHA Doctorado Nacional 2017-21171485 and Proyecto Fondecyt Regular 1150345. J.A.-G. acknowledges support by FONDECYT Iniciacion 11150916. D.M. is also grateful for the hospitality of the Vatican Observatory. This research made use of Astropy, a community-developed core Python package for astronomy; Scikit-learn, NumPy, and matplotlib, a Python library for publication-quality graphics; and Aladin Sky Atlas, developed at CDS, Strasbourg Observatory, France, and TOPCAT.Deep near-IR images from the VISTA Variables in the V a L ctea (VVV) Survey were used to search for RR Lyrae stars within 100 arcmin from the Galactic Center. A large sample of 960 RR Lyrae of type ab (RRab) stars were discovered. A catalog is presented featuring the positions, magnitudes, colors, periods, and amplitudes for the sample, in addition to estimated reddenings, distances, and metallicities, and measured individual relative proper motions. We use the reddening-corrected Wesenheit magnitudes, defined as WKs Ks 0.428 J Ks = - ( - ), in order to isolate bona fide RRL belonging to the Galaxy Center, finding that 30 RRab are foreground/background objects. We measure a range of extinctions from AKs 0.19 = to 1.75 mag for the RRab in this region, finding that large extinction is the main cause of the sample incompleteness. The mean period is P =0.5446±0.0025 days, yielding a mean metallicity of [Fe/H] =-1.30±0.01 (ς = 0.33) dex for the RRab sample in the Galactic Center region. The median distance for the sample is D =8.05±0.02 kpc. We measure the RRab surface density using the less reddened region sampled here, finding a density of 1000 RRab/sq deg at a projected Galactocentric distance RG =1.6 deg. Under simple assumptions, this implies a large total mass (M>109Me) for the old and metal-poor population contained inside RG. We also measure accurate relative proper motions, from which we derive tangential velocity dispersions of ςVl =125.0 and ςVb =124.1 km s-1 along the Galactic longitude and latitude coordinates, respectively. The fact that these quantities are similar indicate that the bulk rotation of the RRab population is negligible, and implies that this population is supported by velocity dispersion. In summary, there are two main conclusions of this study. First, the population as a whole is no different from the outer bulge RRab, predominantly a metal-poor component that is shifted with respect to the Oosterhoff type I population defined by the globular clusters in the halo. Second, the RRab sample, as representative of the old and metal-poor stellar population in the region, has high velocity dispersions and zero rotation, suggesting a formation via dissipational collapse. ©2018. The American Astronomical Society. All rights reserved.https://iopscience.iop.org/article/10.3847/1538-4357/aacf9

Thermal loads inside buildings with phase change materials: Experimental results

AbstractNowadays, European policies are promoting low energy buildings because of the high amount of energy consumption of the building sector. Phase change materials (PCM) have been studied in building implementation as a passive system to reduce the energy demand. Based in the experience obtained in the experimental set-up of Puigverd de Lleida (Spain), this paper pretends to analyze experimentally the PCM performance in a scenario with internal thermal gains. The experiments were done in three different cubicles with the same internal dimensions. The selection of the constructive systems used in these three cubicles allows the authors to evaluate the impact of using PCM in a typical Mediterranean building. A domestic heat pump for summer and an electric radiator for winter were installed to control the internal temperature of the cubicles. The results of summer period experiments show that the PCM cubicle stored the heat produced by the internal loads limiting the heat dissipation to the outer environment. Therefore, the energy consumed by the HVAC system of the PCM cubicle during the cooling period is higher than that of the other cubicles that dissipated the thermal loads according to the thermal resistance of their envelopes. Therefore, the PCM selection should take into account not only the comfort temperature but also the activity and functionality of the building

Physical Demands of Top-class Soccer Assistant Refereeing During High-standard Matches

This study examined the physical demands experienced by top-class assistant referees during high-standard football matches. Computerized match analyses and heart rate recordings were performed on 18 international assistant referees during the FIFA Confederations Cup 2005. Total distance covered averaged 5752+/-554 m, of which 34% was covered at a high-intensity (>13 km.h (-1)). Sidewards movements represented 30% of total match distance. Both total distance (r=0.67; P<0.01) and high-intensity activities (r=0.52; P<0.05) were related to the displacements of the ball in the same match. The distance covered by high-speed running in this tournament was 255% greater (P<0.001) than that covered during the under-17 World Championship 2003. Mean heart rate during the game was 140+/-11 b.min (-1) (78+/-4% HR (max)). Mean heart rate during a 5-min interval of the match was related in part (r=0.31; P<0.001) to the amount of high-intensity activities performed within the same match-period. The results of this study show that the physical demands imposed on assistant referees are influenced by the movements of the ball and the standard of the competition

Four Decades of Studying Global Linear Instability: Progress and Challenges

Global linear instability theory is concerned with the temporal or spatial development of small-amplitude perturbations superposed upon laminar steady or time-periodic three-dimensional flows, which are inhomogeneous in two(and periodic in one)or all three spatial directions.After a brief exposition of the theory,some recent advances are reported. First, results are presented on the implementation of a Jacobian-free Newton–Krylov time-stepping method into a standard finite-volume aerodynamic code to obtain global linear instability results in flows of industrial interest. Second, connections are sought between established and more-modern approaches for structure identification in flows, such as proper orthogonal decomposition and Koopman modes analysis (dynamic mode decomposition), and the possibility to connect solutions of the eigenvalue problem obtained by matrix formation or time-stepping with those delivered by dynamic mode decomposition, residual algorithm, and proper orthogonal decomposition analysis is highlighted in the laminar regime; turbulent and three-dimensional flows are identified as open areas for future research. Finally, a new stable very-high-order finite-difference method is implemented for the spatial discretization of the operators describing the spatial biglobal eigenvalue problem, parabolized stability equation three-dimensional analysis, and the triglobal eigenvalue problem; it is shown that, combined with sparse matrix treatment, all these problems may now be solved on standard desktop computer

HI study of the warped spiral galaxy NGC5055: a disk/dark matter halo offset?

We present a study of the HI distribution and dynamics of the nearby spiral galaxy NGC5055 based on observations with the Westerbork Synthesis Radio Telescope. The gaseous disk of NGC5055 extends out to about 40 kpc, equal to 3.5 R_25, and shows a pronounced warp that starts at the end of the bright optical disk (R_25= 11.6 kpc). This very extended warp has large-scale symmetry, which along with the rotation period of its outer parts (~1.5 Gyr at 40 kpc), suggests a long-lived phenomenon. The rotation curve rises steeply in the central parts up to the maximum velocity (v_max ~ 206 km/s). Beyond the bright stellar disk (R_25), it shows a decline of about 25 km/s and then remains flat out to the last measured point. The standard analysis with luminous and dark matter components shows the dynamical importance of the disk. The best fit to the rotation curve is obtained with a ``maximum disk''. Less satisfactory fits with lighter disks help to set a firm lower limit of 1.4 to the mass-to-light ratio in F band of the disk. Such a ``minimum disk'' contributes about 60% of the observed maximum rotational velocity. NGC5055 shows remarkable overall regularity and symmetry. A mild lopsidedness is noticeable, however, both in the distribution and kinematics of the gas. The tilted ring analysis of the velocity field led us to adopt different values for the kinematical centre and for the systemic velocity for the inner and the outer parts of the system. This has produced a remarkable result: the kinematical and geometrical asymmetries disappear, both at the same time. These results point at two different dynamical regimes: an inner region dominated by the stellar disk and an outer one, dominated by a dark matter halo offset with respect to the disk.Comment: Accepted for publication in A&A. Minor correction

Acute Kidney Injury in the Context of Inflammatory Bowel Disease - A Clinical Case

Extraintestinal manifestations of inflammatory bowel disease are common and extendable to all organs. Kidney and lower genitourinary system occurs in 4-23% of cases. This may be dependent on inflammatory bowel disease activity, secondary to metabolic disorders, drugs or others. We present a case of a 68-year-old man with ulcerative colitis for 22 years admitted in our department for acute nephritic syndrome. Urinary microscopy suggested glomerular injury. A kidney biopsy was performed and was compatible with acute interstitial nephritis and IgA nephropathy. Toxicity of mesalazine and glomerulonephritis secondary to ulcerative colitis were assumed. The patient suspended mesalazine and started prednisolone with clinical improvement. Our purpose is to sensitize the importance of having a prompt and thorough evaluation of acute kidney injury in patients with inflammatory bowel disease. We briefly review the broad spectrum of kidney manifestations in this population, focusing on mesalazine-induced nephrotoxicity.info:eu-repo/semantics/publishedVersio

The PKC, HOG and Ca2+ signalling pathways co-ordinately regulate chitin synthesis in Candida albicans

Open Access via PMC2649417Peer reviewedPublisher PD

A tale of two galaxies: light and mass in NGC891 and NGC7814

The two edge-on galaxies NGC891 and NGC7814 are representative of two extreme morphologies: the former is disk-dominated while the latter is almost entirely bulge-dominated. It has been argued (van der Kruit 1983) that since the two galaxies, which are optically so different, have similar rotation curves their total mass distributions cannot be related in any way to the light distributions. This would lead to the conclusion that dark matter is the dominating component of the mass. We have derived new rotation curves from recent, high-sensitivity HI observations and have found that the shapes of the rotation curves are significantly different for the two galaxies. They indicate that in NGC7814 the mass is more concentrated to the centre as compared to NGC891. This reflects the distribution of light which is more centrally concentrated in NGC7814 than in NGC891. Mass and light do seem to be closely related. This is confirmed by the analysis of the rotation curves in mass components: solutions close to the maximum light (bulge + disk) do provide excellent fits. In NGC891 bulge and disk can explain the rotation curve without any need for dark matter out to ~15 kpc. In NGC7814 the bulge dominates in the inner parts; further out the rotation curve is well reproduced by a maximum disk but its M/L ratio is excessively high. A substantial dark matter contribution, closely coupled to the luminous component, seems, therefore, necessary.Comment: 10 pages, 9 figures, accepted for publication in A&