360 research outputs found

    Photon correlations for colloidal nanocrystals and their clusters

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    Images of semiconductor `dot in rods' and their small clusters are studied by measuring the second-order correlation function with a spatially resolving ICCD camera. This measurement allows one to distinguish between a single dot and a cluster and, to a certain extent, to estimate the number of dots in a cluster. A more advanced measurement is proposed, based on higher-order correlations, enabling more accurate determination of the number of dots in a small cluster. Nonclassical features of the light emitted by such a cluster are analyzed.Comment: 4 pages, 4 figure

    On universality of local edge regime for the deformed Gaussian Unitary Ensemble

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    We consider the deformed Gaussian ensemble Hn=Hn(0)+MnH_n=H_n^{(0)}+M_n in which Hn(0)H_n^{(0)} is a hermitian matrix (possibly random) and MnM_n is the Gaussian unitary random matrix (GUE) independent of Hn(0)H_n^{(0)}. Assuming that the Normalized Counting Measure of Hn(0)H_n^{(0)} converges weakly (in probability if random) to a non-random measure N(0)N^{(0)} with a bounded support and assuming some conditions on the convergence rate, we prove universality of the local eigenvalue statistics near the edge of the limiting spectrum of HnH_n.Comment: 25 pages, 2 figure

    Photon correlations for colloidal nanocrystals and their clusters

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    Images of semiconductor “dot-in-rods” and their small clusters are studied by measuring the second-order correlation function with a spatially resolving intensified CCD camera. This measurement allows one to distinguish between a single dot and a cluster and, to a certain extent, to estimate the number of dots in a cluster. A more advanced measurement is proposed, based on higher-order correlations, enabling more accurate determination of the number of dots in a small cluster. Nonclassical features of the light emitted by such a cluster are analyzed

    Bulk Universality and Related Properties of Hermitian Matrix Models

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    We give a new proof of universality properties in the bulk of spectrum of the hermitian matrix models, assuming that the potential that determines the model is globally C2C^{2} and locally C3C^{3} function (see Theorem \ref{t:U.t1}). The proof as our previous proof in \cite{Pa-Sh:97} is based on the orthogonal polynomial techniques but does not use asymptotics of orthogonal polynomials. Rather, we obtain the sinsin-kernel as a unique solution of a certain non-linear integro-differential equation that follows from the determinant formulas for the correlation functions of the model. We also give a simplified and strengthened version of paper \cite{BPS:95} on the existence and properties of the limiting Normalized Counting Measure of eigenvalues. We use these results in the proof of universality and we believe that they are of independent interest

    General properties of overlap probability distributions in disordered spin systems. Toward Parisi ultrametricity

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    For a very general class of probability distributions in disordered Ising spin systems, in the thermodynamical limit, we prove the following property for overlaps among real replicas. Consider the overlaps among s replicas. Add one replica s+1. Then, the overlap q(a,s+1) between one of the first s replicas, let us say a, and the added s+1 is either independent of the former ones, or it is identical to one of the overlaps q(a,b), with b running among the first s replicas, excluding a. Each of these cases has equal probability 1/s.Comment: LaTeX2e, 11 pages. Submitted to Journal of Physics A: Mathematical and General. Also available at http://rerumnatura.zool.su.se/stefano/ms/ghigu.p

    An overview of TI-RADS systems from a point of view of follicular tumors diagnosis

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    The existing systems for describing thyroid nodules are highly informative and can be applied in routine practice, but suspicious criteria of thyroid nodules are based on the echographic pattern of papillary neoplasia, due to its predominance in the population. Follicular tumors are difficult to be differentiated between adenomas and follicular cancer, both echographically and morphologically. Despite the lower prevalence, this type of tumor has a high risk of aggressive course and relapse of 30–55% and this determines its early detection importance. The analysis of publications from 2009 to 2020 of existing TI‑RADS systems and national guidelines for the diagnosis of thyroid tumors, with an emphasis on the assessment of follicular tumors, was carried out. In Russia, at the beginning of 2021, the national guidelines require the use of EU‑TIRADS 2017, and the introduction of the national RU‑TIRADS is underway. Difficulties remain in the differential diagnosis of follicular tumors of different malignancy potential. It is possible that a combined risk assessment of echography, elastography, cytology, and molecular genetic studies will allow a more reliable stratification of the risks of thyroid nodules at the preoperative stage

    Quantum Zakharov Model in a Bounded Domain

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    We consider an initial boundary value problem for a quantum version of the Zakharov system arising in plasma physics. We prove the global well-posedness of this problem in some Sobolev type classes and study properties of solutions. This result confirms the conclusion recently made in physical literature concerning the absence of collapse in the quantum Langmuir waves. In the dissipative case the existence of a finite dimensional global attractor is established and regularity properties of this attractor are studied. For this we use the recently developed method of quasi-stability estimates. In the case when external loads are CC^\infty functions we show that every trajectory from the attractor is CC^\infty both in time and spatial variables. This can be interpret as the absence of sharp coherent structures in the limiting dynamics.Comment: 27 page

    From salty to fresh—salinity processes in the Upper-ocean Regional Study-2 (SPURS-2) : diagnosing the physics of a rainfall-dominated salinity minimum

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    Author Posting. © The Oceanography Society, 2015. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 28, no. 1 (2015): 150-159, doi:10.5670/oceanog.2015.15.One of the notable features of the global ocean is that the salinity of the North Atlantic is about 1 psu higher than that of the North Pacific. This contrast is thought to be due to one of the large asymmetries in the global water cycle: the transport of water vapor by the trade winds across Central America and the lack of any comparable transport into the Atlantic from the Sahara Desert. Net evaporation serves to maintain high Atlantic salinities, and net precipitation lowers those in the Pacific. Because the effects on upper-ocean physics are markedly different in the evaporating and precipitating regimes, the next phase of research in the Salinity Processes in the Upper-ocean Regional Study (SPURS) must address a high rainfall region. It seemed especially appropriate to focus on the eastern tropical Pacific that is freshened by the water vapor carried from the Atlantic. In a sense, the SPURS-2 Pacific region will be looking at the downstream fate of the freshwater carried out of the SPURS-1 North Atlantic region. Rainfall tends to lower surface density and thus inhibit vertical mixing, leading to quite different physical structure and dynamics in the upper ocean. Here, we discuss the motivations for the location of SPURS-2 and the scientific questions we hope to address
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