7,295 research outputs found

    Management of diabetic macular edema patients in clinical practice in Spain

    Get PDF
    Purpose: Diabetic macular edema is the main cause of blindness in diabetic patients. Vascular endothelial growth factor is involved in diabetic macular edema pathogenesis. Vascular endothelial growth factor inhibitors are an important option in diabetic macular edema therapy. This survey investigates actual clinical practice in diabetic macular edema in Spain. Methods: An expert advisory panel of 17 Spanish ophthalmologists developed a 30-item anonymous questionnaire about diagnosis, treatment, and follow-up in diabetic macular edema. A total of 137 ophthalmologists from 10 Spanish regions completed the questionnaire online. Results: Almost all of the respondents (99.3%) record the measured visual acuity and perform biomicroscopic anterior (94.9%) and posterior (91.2%) segment examinations. Similarly, 100% of responding ophthalmologists always/almost always or frequently perform optical coherence tomography. Most respondents (65%) always/almost always or frequently perform a retinography. More than 50% rarely perform fluorescein angiography. Nearly, all (96.4%) of the specialists responded that, in center-involved diabetic macular edema, the first treatment is an anti–vascular endothelial growth factor drug. For corticosteroids, the first choice of most respondents (91.2%) was the dexamethasone implant. In the follow-up, almost all (96.4%) specialists record the measured visual acuity and most also perform biomicroscopic anterior (82.5%) and posterior (83.2%) segment examination. Conclusion: This survey shows the actual clinical practice in diabetic macular edema in Spain, finding that anti–vascular endothelial growth factor therapy is frequently used, and that diagnosis, treatments, and follow-up examinations used by specialists are homogeneous and according to diabetic macular edema guidelines

    Limits on excited tau leptons masses from leptonic tau decays

    Full text link
    We study the effects induced by excited leptons on the leptonic tau decay at one loop level. Using a general effective lagrangian approach to describe the couplings of the excited leptons, we compute their contributions to the leptonic decays and use the current experimental values of the branching ratios to put limits on the mass of excited states and the substructure scale.Comment: 10 pages, 6 figures, to be published in Phys. Rev.

    Nesting Induced Precursor Effects: a Renormalization Group Approach

    Full text link
    We develop a controlled weak coupling renormalization group (RG) approach to itinerant electrons. Within this formalism we rederive the phase diagram for two-dimensional (2D) non-nested systems. Then we study how nesting modifies this phase diagram. We show that competition between p-p and p-h channels, leads to the manifestation of unstable precursor fixed points in the RG flow. This effect should be experimentally measurable, and may be relevant for an explanation of pseudogaps in the high temperature superconductors (HTC), as a crossover phenomenon.Comment: 4 pages, 4 figures, 1 tabl

    Stellar Population gradients in galaxy discs from the CALIFA survey

    Get PDF
    While studies of gas-phase metallicity gradients in disc galaxies are common, very little has been done in the acquisition of stellar abundance gradients in the same regions. We present here a comparative study of the stellar metallicity and age distributions in a sample of 62 nearly face-on, spiral galaxies with and without bars, using data from the CALIFA survey. We measure the slopes of the gradients and study their relation with other properties of the galaxies. We find that the mean stellar age and metallicity gradients in the disc are shallow and negative. Furthermore, when normalized to the effective radius of the disc, the slope of the stellar population gradients does not correlate with the mass or with the morphological type of the galaxies. Contrary to this, the values of both age and metallicity at \sim2.5 scale-lengths correlate with the central velocity dispersion in a similar manner to the central values of the bulges, although bulges show, on average, older ages and higher metallicities than the discs. One of the goals of the present paper is to test the theoretical prediction that non-linear coupling between the bar and the spiral arms is an efficient mechanism for producing radial migrations across significant distances within discs. The process of radial migration should flatten the stellar metallicity gradient with time and, therefore, we would expect flatter stellar metallicity gradients in barred galaxies. However, we do not find any difference in the metallicity or age gradients in galaxies with without bars. We discuss possible scenarios that can lead to this absence of difference.Comment: 24 pages, 17 figures, accepted for publication in A&

    Video enhancement using adaptive spatio-temporal connective filter and piecewise mapping

    Get PDF
    This paper presents a novel video enhancement system based on an adaptive spatio-temporal connective (ASTC) noise filter and an adaptive piecewise mapping function (APMF). For ill-exposed videos or those with much noise, we first introduce a novel local image statistic to identify impulse noise pixels, and then incorporate it into the classical bilateral filter to form ASTC, aiming to reduce the mixture of the most two common types of noises - Gaussian and impulse noises in spatial and temporal directions. After noise removal, we enhance the video contrast with APMF based on the statistical information of frame segmentation results. The experiment results demonstrate that, for diverse low-quality videos corrupted by mixed noise, underexposure, overexposure, or any mixture of the above, the proposed system can automatically produce satisfactory results

    Ionized gas kinematics of galaxies in the CALIFA survey I: Velocity fields, kinematic parameters of the dominant component, and presence of kinematically distinct gaseous systems

    Full text link
    This work provides an overall characterization of the kinematic behavior of the ionized gas of the galaxies included in the Calar Alto Legacy Integral field Area (CALIFA), offering kinematic clues to potential users of this survey for including kinematical criteria for specific studies. From the first 200 galaxies observed by CALIFA, we present the 2D kinematic view of the 177 galaxies satisfying a gas detection threshold. After removing the stellar contribution, we used the cross-correlation technique to obtain the radial velocity of the dominant gaseous component. The main kinematic parameters were directly derived from the radial velocities with no assumptions on the internal motions. Evidence of the presence of several gaseous components with different kinematics were detected by using [OIII] profiles. Most objects in the sample show regular velocity fields, although the ionized-gas kinematics are rarely consistent with simple coplanar circular motions. 35% of the objects present evidence of a displacement between the photometric and kinematic centers larger than the original spaxel radii. Only 17% of the objects in the sample exhibit kinematic lopsidedness when comparing receding and approaching sides of the velocity fields, but most of them are interacting galaxies exhibiting nuclear activity. Early-type galaxies in the sample present clear photometric-kinematic misaligments. There is evidence of asymmetries in the emission line profiles suggesting the presence of kinematically distinct gaseous components at different distances from the nucleus. This work constitutes the first determination of the ionized gas kinematics of the galaxies observed in the CALIFA survey. The derived velocity fields, the reported kinematic peculiarities and the identification of the presence of several gaseous components might be used as additional criteria for selecting galaxies for specific studies.Comment: 38 pages, 16 figures, 4 tables. Paper accepted for publication in A&

    The Mass-Metallicity relation explored with CALIFA: I. Is there a dependence on the star formation rate?

    Full text link
    We present the results on the study of the global and local M-Z relation based on the first data available from the CALIFA survey (150 galaxies). This survey provides integral field spectroscopy of the complete optical extent of each galaxy (up to 2-3 effective radii), with enough resolution to separate individual HII regions and/or aggregations. Nearly \sim3000 individual HII regions have been detected. The spectra cover the wavelength range between [OII]3727 and [SII]6731, with a sufficient signal-to-noise to derive the oxygen abundance and star-formation rate associated with each region. In addition, we have computed the integrated and spatially resolved stellar masses (and surface densities), based on SDSS photometric data. We explore the relations between the stellar mass, oxygen abundance and star-formation rate using this dataset. We derive a tight relation between the integrated stellar mass and the gas-phase abundance, with a dispersion smaller than the one already reported in the literature (σΔlog(O/H)=\sigma_{\Delta{\rm log(O/H)}}=0.07 dex). Indeed, this dispersion is only slightly larger than the typical error derived for our oxygen abundances. However, we do not find any secondary relation with the star-formation rate, other than the one induced due to the primary relation of this quantity with the stellar mass. We confirm the result using the \sim3000 individual HII regions, for the corresponding local relations. Our results agree with the scenario in which gas recycling in galaxies, both locally and globally, is much faster than other typical timescales, like that of gas accretion by inflow and/or metal loss due to outflows. In essence, late-type/disk dominated galaxies seem to be in a quasi-steady situation, with a behavior similar to the one expected from an instantaneous recycling/closed-box model.Comment: 19 Pages, 8 figures, Accepted for Publishing in Astronomy and Astrophysics (A&A

    Muon conversion to electron in nuclei in type-I seesaw models

    Full text link
    We compute the muon to electron conversion in the type-I seesaw model, as a function of the right-handed neutrino mixings and masses. The results are compared with previous computations in the literature. We determine the definite predictions resulting for the ratios between the muon to electron conversion rate for a given nucleus and the rate of two other processes which also involve a mu-e flavour transition: mu -> e gamma and mu -> eee. For a quasi-degenerate mass spectrum of right-handed neutrino masses -which is the most natural scenario leading to observable rates- those ratios depend only on the seesaw mass scale, offering a quite interesting testing ground. In the case of sterile neutrinos heavier than the electroweak scale, these ratios vanish typically for a mass scale of order a few TeV. Furthermore, the analysis performed here is also valid down to very light masses. It turns out that planned mu -> e conversion experiments would be sensitive to masses as low as 2 MeV. Taking into account other experimental constraints, we show that future mu -> e conversion experiments will be fully relevant to detect or constrain sterile neutrino scenarios in the 2 GeV-1000 TeV mass range.Comment: 32 pages 14 figures, references added and some minor precisions; results unchange

    Can lepton flavor violating interactions explain the atmospheric neutrino problem?

    Get PDF
    We investigate whether flavor changing neutrino interactions (FCNIs) can be sufficiently large to provide a viable solution to the atmospheric neutrino problem. Effective operators induced by heavy boson exchange that allow for flavor changing neutrino scattering off quarks or electrons are related by an SU(2)LSU(2)_L rotation to operators that induce anomalous tau decays. Since SU(2)LSU(2)_L violation is small for New Physics at or above the weak scale, one can use the upper bounds on lepton flavor violating tau decays or on lepton universality violation to put severe, model-independent bounds on the relevant non-standard neutrino interactions. Also ZZ-induced flavor changing neutral currents, due to heavy singlet neutrinos, are too small to be relevant for the atmospheric neutrino anomaly. We conclude that the FCNI solution to the atmospheric neutrino problem is ruled out.Comment: 16 pages, no figures, Late

    Multicenter, International Study of MIC/ MEC Distributions for definition of epidemiological cutoff values for sporothrix species identified by molecular methods

    Get PDF
    Clinical and Laboratory Standards Institute (CLSI) conditions for testing the susceptibilities of pathogenic Sporothrix species to antifungal agents are based on a collaborative study that evaluated five clinically relevant isolates of Sporothrix schenckii sensu lato and some antifungal agents. With the advent of molecular identification, there are two basic needs: to confirm the suitability of these testing conditions for all agents and Sporothrix species and to establish species-specific epidemiologic cutoff values (ECVs) or breakpoints (BPs) for the species. We collected available CLSI MICs/minimal effective concentrations (MECs) of amphotericin B, five triazoles, terbinafine, flucytosine, and caspofungin for 301 Sporothrix schenckii sensu stricto, 486 S. brasiliensis, 75 S. globosa, and 13 S. mexicana molecularly identified isolates. Data were obtained in 17 independent laboratories (Australia, Europe, India, South Africa, and South and North America) using conidial inoculum suspensions and 48 to 72 h of incubation at 35°C. Sufficient and suitable data (modal MICs within 2-fold concentrations) allowed the proposal of the following ECVs for S. schenckii and S. brasiliensis, respectively: amphotericin B, 4 and 4 /ml; itraconazole, 2 and 2 μg/ml; posaconazole, 2 and 2 μg/ml; and voriconazole, 64 and 32 μg/ml. Ketoconazole and terbinafine ECVs for S. brasiliensis were 2 and 0.12 μg/ml, respectively. Insufficient or unsuitable data precluded the calculation of ketoconazole and terbinafine (or any other antifungal agent) ECVs for S. schenckii, as well as ECVs for S. globosa and S. mexicana. These ECVs could aid the clinician in identifying potentially resistant isolates (non-wild type) less likely to respond to therapy.A. Espinel-Ingroff, D. P. B. Abreu, R. Almeida-Paes, R. S. N. Brilhante, A. Chakrabarti, A. Chowdhary, F. Hagen, S. Córdoba, G. M. Gonzalez, N. P. Govender, J. Guarro, E. M. Johnson, S. E. Kidd, S. A. Pereira, A. M. Rodrigues, S. Rozental, M. W. Szeszs, R. Ballesté Alaniz, A. Bonifaz, L. X. Bonfietti, L. P. Borba-Santos, J. Capilla, A. L. Colombo, M. Dolande, M. G. Isla, M. S. C. Melhem, A. C. Mesa-Arango, M. M. E. Oliveira, M. M. Panizo, Z. Pires de Camargo, R. M. Zancope-Oliveira, J. F. Meis, J. Turnidge
    corecore