Invasion threshold in heterogeneous metapopulation networks

We study the dynamics of epidemic and reaction-diffusion processes in metapopulation models with heterogeneous connectivity pattern. In SIR-like processes, along with the standard local epidemic threshold, the system exhibits a global invasion threshold. We provide an explicit expression of the threshold that sets a critical value of the diffusion/mobility rate below which the epidemic is not able to spread to a macroscopic fraction of subpopulations. The invasion threshold is found to be affected by the topological fluctuations of the metapopulation network. The presented results provide a general framework for the understanding of the effect of travel restrictions in epidemic containment.Comment: 4 pages, 2 figure

Observation of coherent Josephson response in the non-linear ab-plane microwave impedance of YBa2Cu3O6.95YBa_{2}Cu_{3}O_{6.95} single crystals

We report novel non-linear phenomena in the $ab$-plane microwave impedance of $YBaCu_{2}O_{7-\delta }$ single crystals. The $R_s$ vs. $H_{rf}$ data are well described by the non-linear RSJ model : $\dot{\phi}+\sin \phi =i_{rf}\cos \omega t$. The entire crystal behaves like a single Josephson junction. The extraordinary coherence of the data suggests an intrinsic mechanism.Comment: 2 pages,1 figure, Submitted to Proc. of M^2SHTSC-V (Beijing), also available at http://sagar.physics.neu.edu/preprint

The role of both location and radiometer accuracy on the SSI performance in discriminating the atmospheric conditions

AbstractThis study addresses the sensitivity of the Sky Status Indicator (SSI) with respect to both the radiometer accuracy and location of three stations included in the ground segment of the Alphasat experiment. The SSI aims at detecting the atmospheric conditions along a slant path, exploiting radiometric data at 20/30 GHz. The analysis is performed on synthetic brightness temperatures computed from a database of radiosonde profiles collected in De Bilt (NL), Milano (I), and Roma (I) through forward modelling. The SSI sensitivity to both radiometric resolution and bias error is computed for elevation angles equal to 27.6, 35.5, 40.2, 69.6, and 90°. Robustness of SSI boundary threshold values between clear and cloudy sky conditions is assessed

Post-harvest non-conventional and traditional methods to control cadophora luteo-olivacea: Skin pitting agent of actinidia chinensis var. deliciosa (A. chev.)

Cadophora luteo-olivacea represents a critical problem for kiwifruit in the post-harvest phase, mainly for its little note epidemiology. The study presented some results about the possibility of preserving kiwifruit from skin pitting symptoms using alternative methods to fungicides. By in vitro assays, antagonist mechanisms of action against pathogen isolates were tested. Trichoderma harzianum (Th1) showed the highest inhibitory activity against C. luteo-olivacea isolates by volatile, non-volatile, and by dual culture assay, displaying an inhibition respectively by 90%, 70.6%, and 78.8%, and with respect to Aureobasidium pullulans (L1 and L8) by 23.3% and 25.8%, 50% and 34.7%, and 22.5% and 23.6%, respectively. Further, the sensitivity on CFU and mycelial growth of C. luteo-olivacea isolates to fludioxonil, and CaCl2 was tested, displaying interesting EC50 values (0.36 and 0.92 g L-1, 22.5 g L-1, respectively). The effect of Brassica nigra defatted meal was tested as biofumigation assays and through FT-IR (Fourier-Transform Infrared) spectroscopy. The above-mentioned treatments were applied in vivo to evaluate their efficacy on kiwifruits. Our data demonstrated that alternative solutions could be considered to control postharvest pathogens such as C. luteo-olivacea

On the outcome in stroke patients one year later: the role of atrial fibrillation

The post-stroke aftermath of patients suffering from atrial fibrillation (AF) is investigated. A total of 104 consecutive patients (80 with AF and 24 without AF) were referred to a rehabilitation centre and enrolled. They underwent a rehabilitative programme. Disability was assessed by using the Functional Independence Measure (FIM), at the time of admission, discharge and after 1 year. Death was more frequent over the 1-year interval in AF group. Ten patients died (42%), whereas in the non-AF group death occurred in 15 cases (19%). By using chi-square test, the difference was significant (P < 0.02). The logistic regression analysis indicated that the unique variable affecting the FIM at follow-up was the FIM at discharge (P < 0.0001). AF was not a significant variable in the equation. The result can be attributed to subject attrition in the AF group, as the most severe patients died and survivors could benefit from a better functional status

Identification of rainy periods from ground based microwave radiometry

AbstractIn this paper the authors present the results of a study aiming at detecting rainy data in measurements collected by a dual band ground-based radiometer.The proposed criterion is based on the ratio of the brightness temperatures observed in the 20–30 GHz band without need of any ancillary information. A major result obtained from the probability density of the ratio computed over one month of data is the identification of threshold values between clear sky, cloudy sky and rainy sky, respectively. A linear fit performed by using radiometric data and concurrent rain gauge measurements shows a correlation coefficient equal to 0.56 between the temperature ratio and the observed precipitation

Effects of caspofungin against Candida guilliermondii and Candida parapsilosis.

The in vitro activity of caspofungin (CAS) was investigated against 28 yeast isolates belonging to Candida albicans (n = 5), Candida guilliermondii (n = 10), and Candida parapsilosis (n = 13). CAS MICs obtained by broth dilution and Etest methods clearly showed a rank order of susceptibility to the echinocandin compound with C. albicans > C. parapsilosis > C. guilliermondii. Similarly, time-kill assays performed on selected isolates showed that CAS was fungistatic against C. albicans and C. parapsilosis, while it did not exert any activity against C. guilliermondii. In a murine model of systemic candidiasis, CAS given at doses as low as 1 mg/kg of body weight/day was effective at reducing the kidney burden of mice infected with either C. albicans or C. guilliermondii isolates. Depending on the isolate tested, mice infected with C. parapsilosis responded to CAS given at 1 and/or 5 mg/kg/day. However, the overall CFU reduction for C. guilliermondii and C. parapsilosis was approximately 100-fold less than that for C. albicans. Our study shows that CAS was active in experimental systemic candidiasis due to C. guilliermondii and C. parapsilosis, but this activity required relatively high drug dosages

Dynamic and hybrid variational multiscale models for the simulation of bluff-body flows on unstructured grids

The computation of massively separated flows is a challenging problem of particular in- terest in industrial applications. For the purpose of properly simulating these complex flows on not too heavy unstructured meshes as usually employed in industry, appropriate numerical and turbulent models must be used. In the present work, the computation of the flow past a circular cylinder at different Reynolds numbers is chosen as benchmark. The spatial discretization is based on a mixed finite element/finite volume formulation on unstructured grids. The numerical dissipation of the upwind scheme is made of sixth-order space derivatives in order to limit as far as possible the interactions between numerical and subgrid scale (SGS) dissipation, which could deteriorate the accuracy of the results [4]. A variational multi-scale large-eddy simulation (VMS-LES) with dynamic SGS models and a RANS/VMS-LES model are evaluated on the proposed benchmark for subcritical and supercritical flow regimes respectively (see Fig. 1 and Tab. 1). In the VMS-LES used in this work, the separation between the large and the small resolved scales is obtained through a variational projection operator based on spatial average on agglomerated cells [1]. The dynamic procedure allows the adaptation of the constant of the SGS model to the spatial and temporal variation of the flow characteristics, while the VMS formulation restricts the SGS model effects to the smallest resolved scales. The dynamic versions of the Smagorinsky and of the WALE SGS models are considered herein. The non-dynamic counterparts of these SGS models are also used in order to evaluate the impact of dy- namic SGS modeling in the considered VMS-LES approach for the simulation of massively separated flows. However, the Reynolds number range useful for LES-like simulation is limited as LES grid needs to be sufficiently fine to resolve a significant part of the turbulence scales. With the aim of simulating high Reynolds number flows, it is considered in the present work a hybridization strategy using a blending parameter, such that a VMS- LES simulation is obtained where the grid resolution is fine enough to resolve a significant part of the turbulence fluctuations [2], while a RANS model is acting in the regions of coarse grid resolution, as, for instance, near the body surface

Nano granular metallic Fe - oxygen deficient TiO2−δ_{2-\delta} composite films: A room temperature, highly carrier polarized magnetic semiconductor

Nano granular metallic iron (Fe) and titanium dioxide (TiO$_{2-\delta}$) were co-deposited on (100) lanthanum aluminate (LaAlO$_3$) substrates in a low oxygen chamber pressure using a pulsed laser ablation deposition (PLD) technique. The co-deposition of Fe and TiO$_2$ resulted in $\approx$ 10 nm metallic Fe spherical grains suspended within a TiO$_{2-\delta}$ matrix. The films show ferromagnetic behavior with a saturation magnetization of 3100 Gauss at room temperature. Our estimate of the saturation magnetization based on the size and distribution of the Fe spheres agreed well with the measured value. The film composite structure was characterized as p-type magnetic semiconductor at 300 K with a carrier density of the order of $10^{22} /{\rm cm^3}$. The hole carriers were excited at the interface between the nano granular Fe and TiO$_{2-\delta}$ matrix similar to holes excited in the metal/n-type semiconductor interface commonly observed in Metal-Oxide-Semiconductor (MOS) devices. From the large anomalous Hall effect directly observed in these films it follows that the holes at the interface were strongly spin polarized. Structure and magneto transport properties suggested that these PLD films have potential nano spintronics applications.Comment: 6 pages in Latex including 8 figure

Localization of orexin B and receptor 2 for orexins in testicular cytotypes of the camelid alpaca (Vicugna pacos).

The orexins A (OxA) and B (OxB) are two hypothalamic peptides involved in many physiological functions of the mammalian body. They act through the binding of two G-coupled receptors named receptor 1 (OX1 ) and receptor 2 (OX2 ) for orexins. The first receptor is specific for OxA, while the second binds both the substances with equal affinity. The orexins and the relative receptors have been traced by means of different techniques also at the periphery of the body and particularly in the adrenals, and in gastrointestinal and genital organs. Aim of this work was to investigate the presence of OxB and OX2 by means of immunohistochemistry and Western blotting analysis in the testis of the South American camelid alpaca, a species primarily breed in Chile and Ecuador and recently diffused in Europe where the quality of its wool is particularly appreciated. OxB immunoreactivity (IR) was found in the tubular compartment of the testis where spermatogonia (resting), zygotene and pachytene spermatocytes, and spermatids clearly showed differently sized and shaped cytoplasmic positive structures. OX2 -IR was found both in the interstitial and tubular compartments of the testis and particularly in Leydig cells and round and elongated spermatids. Western blotting analysis of testis lysates showed the presence of a protein band whose molecular weight corresponded to that currently assigned to OX2 . Such findings easily translate the hypothesis that OxB and its receptor 2 play a functional role both in the interstitial and tubular compartments of the alpaca testis