499 research outputs found

    Extreme nonlinear electrodynamics in metamaterials with very small linear dielectric permittivity

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    We consider a sub-wavelength periodic layered medium whose slabs are filled by arbitrary linear metamaterials and standard nonlinear Kerr media and we show that the homogenized medium behaves as a Kerr medium whose parameters can assume values not available in standard materials. Exploiting such a parameter availability, we focus on the situation where the linear relative dielectric permittivity is very small thus allowing the observation of the extreme nonlinear regime where the nonlinear polarization is comparable with or even greater than the linear part of the overall dielectric response. The behavior of the electromagnetic field in the extreme nonlinear regime is very peculiar and characterized by novel features as, for example, the transverse power flow reversing. In order to probe the novel regime, we consider a class of fields (transverse magnetic nonlinear guided waves) admitting full analytical description and we show that these waves are allowed to propagate even in media with ϵ0\epsilon0 since the nonlinear polarization produces a positive overall effective permittivity. The considered nonlinear waves exhibit, in addition to the mentioned features, a number of interesting properties like hyper-focusing induced by the phase difference between the field components.Comment: 12 pages, 7 figure

    Sex-related differences and chronobiology of ST-elevation myocardial infarction: findings from a single hub center in Italy

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    Objective: Type I acute myocardial infarction (AMI) is a life-threatening condition. Time of event and rescue procedures, and sex-specific differences may play a crucial role. We aimed to investigate chronobiological patterns and sex-specific differences in a cohort of AMI patients referred to a single hub center in Italy. Patients and methods: We considered all patients consecutively admitted for AMI (STEMI) to the Hospital of the Heart, in Massa, Tuscany (a region of Italy), between 2006 to 2018, who underwent interventional procedures. Sex, age, time of hospital admission, outcome (discharged alive/deceased), main comorbidities, and time between symptom onset and emergency medical service (EMS) activation, were analyzed. Chronobiologic analysis was applied according to hour of day, month, and season of the year. Results: Overall 2,522 patients (mean age 64.6±13.1 years, 73% males) were considered. In-hospital death (IHM) occurred in 96 subjects (3.8%). At univariate analysis, deceased subjects were more likely to be female, older, with longer wait for EMS activation and with interventional procedures during night-time. The multivariate analysis identified female sex, age, history of ischemic heart disease, and night-time interventional procedure as independently associated factors to IHM. Chronobiologic analysis showed a pattern with a main morning peak for total sample, males, and females (p=0.00027; p=0.0006); p=0.0121, respectively). Events showed a higher peak in summer, with no differences by sex, but IHM was higher in winter. Females showed a higher delay for EMS activation, compared to males (p<0.001), but with no effects on prognosis. On the contrary, males with a delay showed higher mortality. Conclusions: Great effort should be spent to reduce patient-related delays in interventional procedures, being this issue crucial in both sexes

    X-ray and Radio Interactions in the Cores of Cooling Flow Clusters

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    We present high resolution ROSAT x-ray and radio observations of three cooling flow clusters containing steep spectrum radio sources at their cores. All three systems exhibit strong signs of interaction between the radio plasma and the hot intracluster medium. Two clusters, A133 and A2626, show enhanced x-ray emission spatially coincident with the radio source whereas the third cluster, A2052, exhibits a large region of x-ray excess surrounding much of the radio source. Using 3-D numerical simulations, we show that a perturbed jet propagating through a cooling flow atmosphere can give rise to amorphous radio morphologies, particularly in the case where the jet was ``turned off'' and allowed to age passively. In addition, the simulated x-ray surface brightness produced both excesses and deficits as seen observationally.Comment: 25 pages, 10 figures, accepted for publication in A

    TRAIL Dependent Fratricidal Killing of gp120 Primed Hepatocytes by HCV Core Expressing Hepatocytes

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    The mechanism by which HIV and HCV cooperatively accelerate hepatocyte damage is not clearly understood; however, each virus affects the TRAIL: TRAIL- receptor system. We, therefore, questioned whether the independent effects of HCV and HIV combine to synergistically result in TRAIL dependent hepatocyte killing. We describe that Huh7 hepatocytes treated with HIV gp120 results in both increase TRAIL-R2 expression and an acquired sensitivity to TRAIL mediated killing. Moreover HCV infection and HCV core expression alone in Huh7 cells upregulates TRAIL. Co-incubation of HIV gp120 primed hepatocytes with HCV core expressing hepatocytes results in the selective death of the HIV gp120 primed hepatocytes that is selectively blocked by TRAIL–R2-Fc fusion protein. Liver biopsies from HIV mono-infected patients have increased TRAIL-R2; biopsies from HCV infected patients have increased TRAIL, while co-infected liver biopsies have increased PARP cleavage within hepatocytes indicating enhanced apoptosis. These findings suggest a pathogenic model to understand why HIV/HCV co-infection accelerates liver injury

    The Richardson's Law in Large-Eddy Simulations of Boundary Layer flows

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    Relative dispersion in a neutrally stratified planetary boundary layer (PBL) is investigated by means of Large-Eddy Simulations (LES). Despite the small extension of the inertial range of scales in the simulated PBL, our Lagrangian statistics turns out to be compatible with the Richardson t3t^3 law for the average of square particle separation. This emerges from the application of nonstandard methods of analysis through which a precise measure of the Richardson constant was also possible. Its values is estimated as C20.5C_2\sim 0.5 in close agreement with recent experiments and three-dimensional direct numerical simulations.Comment: 15 LaTex pages, 4 PS figure

    Management and efficacy of intensified insulin therapy starting in outpatients

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    Diabetic patients under multiple injection insulin therapy (i.e., intensified insulin therapy, IIT) usually start this treatment during hospitalization. We report here on the logistics, efficacy, and safety of IIT, started in outpatients. Over 8 months, 52 type I and type II diabetics were followed up whose insulin regimens consecutively had been changed from conventional therapy to IIT. Two different IIT strategies were compared: free mixtures of regular and intermediate (12 hrs)-acting insulin versus the basal and prandial insulin treatment with preprandial injections of regular insulin, and ultralente (24 hrs-acting) or intermediate insulin for the basal demand. After 8 months HbA1 levels had decreased from 10.6%±2.4% to 8.0%±1.3% (means±SD). There was no difference between the two regimens with respect to metabolic control; but type II patients maintained the lowered HbA1 levels better than type I patients. Only two patients were hospitalized during the follow-up time because of severe hypoglycemia. An increase of body weight due to the diet liberalization during IIT became a problem in one-third of the patients. Our results suggest that outpatient initiation of IIT is safe and efficacious with respect to near-normoglycemic control. Weight control may become a problem in IIT patients

    Determinants of barley grain yield in drought-prone Mediterranean environments

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    The determinants of barley grain yield in drought-prone Mediterranean environments have been studied in the Nure x Tremois (NT) population. A large set of yield and other morpho-physiological data were recorded in 118 doubled haploid (DH) lines of the population, in multi-environment field trials (18 site-year combination). Agrometeorological variables have been recorded and calculated at each site too. Four main periods of barley development were considered, vegetative, reproductive early and late grain filling phases, to dissect the effect on yield traits of the growth phases. Relationships between agrometeorological variables, grain yield (GY) and its main components (GN and GW) were also investigated by correlation. Results firstly gave a clear indication of the involvement of water consumption in determining GY and GW (r2=0.616, P=0.007 and r2=0.703, P=0.005, respectively) calculated from sowing to the early grain filling period, while GN showed its highest correlation with the total photothermal quotient (PQ) calculated for the same period (r2=0.646, P=0.013). With the only exception of total PQ calculated during the vegetative period, all significant correlations with GY were associated to water-dependent agrometeorological parameters. As a second result, the NT segregating population allowed us to weight the amount of interaction due to genotypes over environments or to environments in relation to genotypes by a GGE analysis; 47.67% of G+GE sum of squares was explained by the first two principal components. Then, the introduction of genomic information at major barley genes regulating the length of growth cycle allowed us to explain patterns of adaptation of different groups of NT lines according to the variants (alleles) harbored at venalization (Vrn-H1) in combination with earliness (Eam6) genes. The superiority of the lines carrying the Nure allele at Eam6 was confirmed by factorial ANOVA testing the four possible haplotypes obtained combining alternative alleles at Eam6 and Vrn-H1. Maximum yield potential and differentials among the NT genotypes was finally explored through Finlay-Wilkinson model to interpret grain yield of NT genotypes together with yield adaptability (Ya), as the regression coefficient bi; Ya ranged from 0.71 for NT77 to 1.20 for NT19. Lines simply harboring the Nure variants at the two genes behaved as highest yielding (3.04 t ha\u20131), and showed the highest yield adaptability (bi=1.05). The present study constitutes a starting point towards the introduction of genomic variables in agronomic models for barley grain yield in Mediterranean environments

    Eddy diffusivities for the convective boundary layer derived from LES spectral data

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    AbstractLarge Eddy Simulation (LES) spectral data and Taylor statistical diffusion theory are used to obtain Eddy diffusivities in a convective boundary layer. The derivation employs a fitting expression obtained from LES data for the vertical peak frequency. The vertical Eddy diffusivities are well behaved and show similar patterns and magnitudes as those derived from experimental spectral peak frequency data. In addition, this new vertical Eddy diffusivity was introduced into an advection diffusion equation which was solved by Generalized Integral Laplace Transform Technique (GILLT) method and validated with observed contaminant concentration data of the Copenhagen experiment. The results of this new approach are shown to agree with the measurements of Copenhagen

    An ISOCAM survey through gravitationally lensing galaxy clusters. III. New results from mid-infrared observations of th e cluster Abell 2219

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    The massive cluster of galaxies Abell 2219 (z = 0.228) was observed at 14.3 μ\mum with the Infrared Space Observatory and results were published by Barvainis et al. (1999). These observations have been reanalyzed using a method specifically designed for the detection of faint sources that had been applied to other clusters. Five new sources were detected and the resulting cumulative total of ten sources all have optical counterparts. The mid-infrared sources are identified with three cluster members, three foreground galaxies, an Extremely Red Object, a star and two galaxies of unknown redshift. The spectral energy distributions (SEDs) of the galaxies are fit with models from a selection, using the program GRASIL. Best-fits are obtained, in general, with models of galaxies with ongoing star formation. For three cluster members the infrared luminosities derived from the model SEDs are between ~5.7x10^10 Lsun and 1.4x10^11 Lsun, corresponding to infrared star formation rates between 10 and 24 Msun yr^-1. The two cluster galaxies that have optical classifications are in the Butcher-Oemler region of the color-magnitude diagramme. The three foreground galaxies have infrared luminosities between 1.5x10^10 Lsun and 9.4x10^10 Lsun yielding infrared star formation rates between 3 and 16 Msun yr^-1. Two of the foreground galaxies are located in two foreground galaxy enhancements (Boschin et al. 2004). Including Abell 2219, six distant clusters of galaxies have been mapped with ISOCAM and luminous infrared galaxies (LIRGs) have been found in three of them. The presence of LIRGs in Abell 2219 strengthens the association between luminous infrared galaxies in clusters and recent or ongoing cluster merger activity.Comment: 8 pages, 4 figures, A&A accepted, full paper with high-resolution figures available at http://bermuda.ucd.ie/~dcoia/papers/. Reference adde
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