17,592 research outputs found

    Growth patterns and scaling laws governing AIDS epidemic in Brazilian cities

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    Brazil holds approximately 1/3 of population living infected with AIDS (acquired immunodeficiency syndrome) in Central and South Americas, and it was also the first developing country to implement a large-scale control and intervention program against AIDS epidemic. In this scenario, we investigate the temporal evolution and current status of the AIDS epidemic in Brazil. Specifically, we analyze records of annual absolute frequency of cases for more than 5000 cities for the first 33 years of the infection in Brazil. We found that (i) the annual absolute frequencies exhibit a logistic-type growth with an exponential regime in the first few years of the AIDS spreading; (ii) the actual reproduction number decaying as a power law; (iii) the distribution of the annual absolute frequencies among cities decays with a power law behavior; (iv) the annual absolute frequencies and the number of inhabitants have an allometric relationship; (v) the temporal evolution of the annual absolute frequencies have different profile depending on the average annual absolute frequencies in the cities. These findings yield a general quantitative description of the AIDS infection dynamics in Brazil since the beginning. They also provide clues about the effectiveness of treatment and control programs against the infection, that has had a different impact depending on the number of inhabitants of cities. In this framework, our results give insights into the overall dynamics of AIDS epidemic, which may contribute to select empirically accurate models.Comment: 12 pages, 6 figure

    Linear Theory of Electron-Plasma Waves at Arbitrary Collisionality

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    The dynamics of electron-plasma waves are described at arbitrary collisionality by considering the full Coulomb collision operator. The description is based on a Hermite-Laguerre decomposition of the velocity dependence of the electron distribution function. The damping rate, frequency, and eigenmode spectrum of electron-plasma waves are found as functions of the collision frequency and wavelength. A comparison is made between the collisionless Landau damping limit, the Lenard-Bernstein and Dougherty collision operators, and the electron-ion collision operator, finding large deviations in the damping rates and eigenmode spectra. A purely damped entropy mode, characteristic of a plasma where pitch-angle scattering effects are dominant with respect to collisionless effects, is shown to emerge numerically, and its dispersion relation is analytically derived. It is shown that such a mode is absent when simplified collision operators are used, and that like-particle collisions strongly influence the damping rate of the entropy mode.Comment: 23 pages, 10 figures, accepted for publication on Journal of Plasma Physic

    On Exact and Approximate Solutions for Hard Problems: An Alternative Look

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    We discuss in an informal, general audience style the da Costa-Doria conjecture about the independence of the P = NP hypothesis and try to briefly assess its impact on practical situations in economics. The paper concludes with a discussion of the Coppe-Cosenza procedure, which is an approximate, partly heuristic algorithm for allocation problems.P vs. NP , allocation problem, assignment problem, traveling salesman, exact solution for NP problems, approximate solutions for NP problems, undecidability, incompleteness

    Optimization and validation of a new cytology stain – CytoPath line®

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    Cytology plays an important role in the screening and diagnosis of cervical cancer. The correct staining of cervical smear allows the recognition of essential characteristics for the diagnosis of some pathologies. However, given the existence of flaws in the current staining procedures, the development of new staining techniques as well as the optimization of the existing ones is important. Recently, a new staining line - the CytoPath line® is being developed by DiaPath S.p.A. The objective of this work is to evaluate its performance in the staining of gynecological cytology samples.info:eu-repo/semantics/publishedVersio

    Impact of pelvic radiotherapy on female sexuality

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    PURPOSE: To assess physical and psychological morbidity, sexual functioning and social and relationship satisfaction among women treated with pelvic radiotherapy. METHODS: Observational (case-control) study of 199 women: 98 submitted to pelvic radiotherapy for the treatment of uterine, rectal or anal cancers and 101 without a personal history of cancer and similar socio-demographic variables. These completed a socio-demographic and clinical questionnaire, and validated measures of psychological health (DASS: Lovibond and Lovibond in Behav Res Ther 33:353-343, 1995), sexual function (FSFI: Rosen et al. in J Sex Marital Ther 26:191-208, 2007), social support (ESSS: Ribeiro in Analise Psicologica 3:547-558, 1999) and relationship satisfaction (IMS: Hudson in The WALMYR assessment scales scoring manual 1992). RESULTS: Women submitted to pelvic irradiation reported a higher rate of adverse physical symptoms in the last month: fatigue 59 versus 25% (p < 0.001), lack of strength 42 versus 20% (p = 0.001), diarrhoea 24 versus 12% (p = 0.032), vaginal discharge 17 versus 7% (p = 0.024), skin erythema 9 versus 2% (p = 0.026). Levels of depression, anxiety and stress were higher among radiotherapy patients, but only reach statistical significance for the stress parameter (6.1 vs. 4.0, p = 0.012). Also these women reported lower scores of satisfaction with social support (57.2 vs. 62.2, p = 0.005) and sexual function (8.5 vs. 13.5, p = 0.049). No statistically significant differences occurred between the two groups regarding scores of relationship satisfaction (20.8 vs. 19.9, p = n.s.). CONCLUSIONS: Our results suggested that pelvic radiotherapy had a negative impact on female sexuality. Thus, interventions that would help to reduce this impact need to be designed and integrated into routine clinical practice

    Microwave probes Dipole Blockade and van der Waals Forces in a Cold Rydberg Gas

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    We show that microwave spectroscopy of a dense Rydberg gas trapped on a superconducting atom chip in the dipole blockade regime reveals directly the dipole-dipole many-body interaction energy spectrum. We use this method to investigate the expansion of the Rydberg cloud under the effect of repulsive van der Waals forces and the breakdown of the frozen gas approximation. This study opens a promising route for quantum simulation of many-body systems and quantum information transport in chains of strongly interacting Rydberg atoms.Comment: PACS: 03.67.-a, 32.80.Ee, 32.30.-
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