351 research outputs found

    Nephrogenic Diabetes Insipidus – The Novelly Potential Therapeutic Drugs

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    A separating problem on function spaces

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    Variability of organic and elemental carbon, water soluble organic carbon, and isotopes in Hong Kong

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    International audienceTo determine the levels and variations of carbonaceous aerosol in Hong Kong, PM2.5 and PM10 samples were collected by high volume (Hi-vol) samplers at three monitoring stations (representing middle-scale roadside, urban-, and regional-scale environments) during winter (November 2000 to February 2001) and summer (June 2001 to August 2001) periods. The highest concentrations of organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC) were found at the middle-scale roadside site with the lowest at the regional-scale site. The percentages of WSOC in total carbon at these sites were inversely correlated with their concentrations (i.e., the highest percentages of WSOC were observed at the regional-scale site). A high WSOC fraction may be associated with aged aerosol because of the secondary formation by photochemical oxidation of organic precursors of anthropogenic pollutants during transport. The annual average of isotope abundances (?13C) of OC and EC were ?26.9±0.5? and ?25.6±0.1?, respectively. There were no notable differences for seasonal distributions of carbon isotopic composition, consistent with motor vehicle emissions being the main source contributors of carbonaceous aerosol in Hong Kong. OC 13C abundances at the regional-scale site were higher than those at the middle-scale roadside and urban sites, consistent with secondary organic aerosols of biogenic origin

    Moderate deviations for random field Curie-Weiss models

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    The random field Curie-Weiss model is derived from the classical Curie-Weiss model by replacing the deterministic global magnetic field by random local magnetic fields. This opens up a new and interestingly rich phase structure. In this setting, we derive moderate deviations principles for the random total magnetization SnS_n, which is the partial sum of (dependent) spins. A typical result is that under appropriate assumptions on the distribution of the local external fields there exist a real number mm, a positive real number λ\lambda, and a positive integer kk such that (Snnm)/nα(S_n-nm)/n^{\alpha} satisfies a moderate deviations principle with speed n12k(1α)n^{1-2k(1-\alpha)} and rate function λx2k/(2k)!\lambda x^{2k}/(2k)!, where 11/(2(2k1))<α<11-1/(2(2k-1)) < \alpha < 1.Comment: 21 page

    Complete characterization of convergence to equilibrium for an inelastic Kac model

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    Pulvirenti and Toscani introduced an equation which extends the Kac caricature of a Maxwellian gas to inelastic particles. We show that the probability distribution, solution of the relative Cauchy problem, converges weakly to a probability distribution if and only if the symmetrized initial distribution belongs to the standard domain of attraction of a symmetric stable law, whose index α\alpha is determined by the so-called degree of inelasticity, p>0p>0, of the particles: α=21+p\alpha=\frac{2}{1+p}. This result is then used: (1) To state that the class of all stationary solutions coincides with that of all symmetric stable laws with index α\alpha. (2) To determine the solution of a well-known stochastic functional equation in the absence of extra-conditions usually adopted

    Isotropic photonic band gap and anisotropic structures in transmission spectra of two-dimensional 5-fold and 8-fold symmetric quasiperiodic photonic crystals

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    We measured and calculated transmission spectra of two-dimensional quasiperiodic photonic crystals (PCs) based on a 5-fold (Penrose) or 8-fold (octagonal) symmetric quasiperiodic pattern. The photonic crystal consisted of dielectric cylindrical rods in air placed normal to the basal plane on vertices of tiles composing the quasiperiodic pattern. An isotropic photonic band gap (PBG) appeared in the TM mode, where electric fields were parallel to the rods, even when the real part of a dielectric constant of the rod was as small as 2.4. An isotropic PBG-like dip was seen in tiny Penrose and octagonal PCs with only 6 and 9 rods, respectively. These results indicate that local multiple light scattering within the tiny PC plays an important role in the PBG formation. Besides the isotropic PBG, we found dips depending on the incident angle of the light. This is the first report of anisotropic structures clearly observed in transmission spectra of quasiperiodic PCs. Based on rod-number and rod-arrangement dependence, it is thought that the shapes and positions of the anisotropic dips are determined by global multiple light scattering covering the whole system. In contrast to the isotropic PBG due to local light scattering, we could not find any PBGs due to global light scattering even though we studied transmission spectra of a huge Penrose PC with 466 rods.Comment: One tex file for manuscript and 12 PNG files for figures consisting of Fig.1a-d, 2,3, ...

    Probabilistic study of the speed of approach to equilibrium for an inelastic Kac model

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    This paper deals with a one--dimensional model for granular materials, which boils down to an inelastic version of the Kac kinetic equation, with inelasticity parameter p>0p>0. In particular, the paper provides bounds for certain distances -- such as specific weighted χ\chi--distances and the Kolmogorov distance -- between the solution of that equation and the limit. It is assumed that the even part of the initial datum (which determines the asymptotic properties of the solution) belongs to the domain of normal attraction of a symmetric stable distribution with characteristic exponent \a=2/(1+p). With such initial data, it turns out that the limit exists and is just the aforementioned stable distribution. A necessary condition for the relaxation to equilibrium is also proved. Some bounds are obtained without introducing any extra--condition. Sharper bounds, of an exponential type, are exhibited in the presence of additional assumptions concerning either the behaviour, near to the origin, of the initial characteristic function, or the behaviour, at infinity, of the initial probability distribution function

    Search for a strongly decaying neutral charmed pentaquark

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    We present a search for a charmed pentaquark decaying strongly to D()pD^{(*)-}p. Finding no evidence for such a state, we set limits on the cross section times branching ratio relative to DD^{*-} and DD^- under particular assumptions about the production mechanism.Comment: To be published in Physics Letters

    An Excursion-Theoretic Approach to Stability of Discrete-Time Stochastic Hybrid Systems

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    We address stability of a class of Markovian discrete-time stochastic hybrid systems. This class of systems is characterized by the state-space of the system being partitioned into a safe or target set and its exterior, and the dynamics of the system being different in each domain. We give conditions for L1L_1-boundedness of Lyapunov functions based on certain negative drift conditions outside the target set, together with some more minor assumptions. We then apply our results to a wide class of randomly switched systems (or iterated function systems), for which we give conditions for global asymptotic stability almost surely and in L1L_1. The systems need not be time-homogeneous, and our results apply to certain systems for which functional-analytic or martingale-based estimates are difficult or impossible to get.Comment: Revised. 17 pages. To appear in Applied Mathematics & Optimizatio
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