457 research outputs found

    Clinical trial of time-resolved scanning optical mammography at 4 wavelengths between 683 and 975 nm

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    The first time-resolved optical mammograph operating beyond 900 nm (683, 785, 913, and 975 nm) is presently being used in a clinical trial to test the diagnostic potential of the technique in detecting and characterizing breast lesions. Between November 2001 and October 2002, 101 patients with malignant and benign lesions were analyzed retrospectively. Scattering plots, as derived from a homogeneous model, and late gated intensity images, to monitor spatial changes in the absorption properties, are routinely used. The intensity images available at four wavelengths provide sensitivity to the main tissue constituents (oxy- and deoxyhemoglobin, water, and lipids), in agreement with expected tissue composition and physiology, while the scattering plots mirror structural changes. Briefly, tumors are usually identified due to the strong blood absorption at short wavelengths, cysts to the low scattering, and fibroadenomas to low absorption at 913 nm and high at 975 nm, even though the optical features of fibroadenomas seem not to be uniquely defined. The effectiveness of the technique in localizing and discriminating different lesion types is analyzed as a function of various parameters (lesion size, compressed breast thickness, and breast parenchymal pattern).

    The temporal patterns of disease severity and prevalence in schistosomiasis

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    Schistosomiasis is one of the most widespread public health problems in the world. In this work, we introduce an eco-epidemiological model for its transmission and dynamics with the purpose of explaining both intra-and inter-annual fluctuations of disease severity and prevalence. The model takes the form of a system of nonlinear differential equations that incorporate biological complexity associated with schistosome's life cycle, including a prepatent period in snails (i.e., the time between initial infection and onset of infectiousness). Nonlinear analysis is used to explore the parametric conditions that produce different temporal patterns (stationary, endemic, periodic, and chaotic). For the time-invariant model, we identify a transcritical and a Hopf bifurcation in the space of the human and snail infection parameters. The first corresponds to the occurrence of an endemic equilibrium, while the latter marks the transition to interannual periodic oscillations. We then investigate a more realistic time-varying model in which fertility of the intermediate host population is assumed to seasonally vary. We show that seasonality can give rise to a cascade of period-doubling bifurcations leading to chaos for larger, though realistic, values of the amplitude of the seasonal variation of fertility. (C) 2015 AIP Publishing LLC

    Frame-based multiple-description video coding with extended orthogonal filter banks

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    We propose a frame-based multiple-description video coder. The analysis filter bank is the extension of an orthogonal filter bank which computes the spatial polyphase components of the original video frames. The output of the filter bank is a set of video sequences which can be compressed with a standard coder. The filter bank design is carried out by taking into account two important requirements for video coding, namely, the fact that the dual synthesis filter bank is FIR, and that loss recovery does not enhance the quantization error. We give explicit results about the required properties of the redundant channel filter and the reconstruction error bounds in case of packet errors. We show that the proposed scheme has good error robustness to losses and good performance, both in terms of objective and visual quality, when compared to single description and other multiple description video coders based on spatial subsampling. PSNR gains of 5 dB or more are typical for packet loss probability as low as 5%

    MODELLI SPAZIO-TEMPORALI DI DIFFUSIONE, PREVISIONE E CONTROLLO DELLE EPIDEMIE DI COLERA: DAL SUDAFRICA AD HAITI

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    Understanding, predicting and controlling the dynamics of cholera and other waterborne diseases are crucial goals of public health policies. Appropriate quantitative models to forecast epidemic development and to evaluate possible intervention scenarios would be specially needed during epidemic outbreaks, when preparedness and efficient allocation of resources are key to emergency management. Moreover, these tools ought to be spatially explicit, because waterborne disease epidemics usually display spatially inhomogeneous patterns. Here we describe spatially explicit epidemiological models and methods for real-time forecast of waterborne disease epidemics and design of intervention strategies for epidemic prevention and control. Applications to two cholera epidemics in South Africa and Haiti are briefly illustrated

    QR code and the wine sector: What contents? an exploratory research study on the wine industry

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    This paper presents an explorative analysis of the contents shared through QR codes as a tool of proximity marketing. The aim of the research is to identify the most common links shared through the QR code technology, in order to investigate the use of this tool from a marketing point of view. Moreover, the research explores the main aspects of the communications related to the contents shared through QR codes. Specifically, the authors focus on hedonic aspects and functional ones. Finally, the research aims at identifying preliminary best practices in the use of QR code technology. Due to the widespread use of this tool in the sector, the research focuses on the wine industry, as one of the most involved with QR code practices. The study adopts a qualitative approach based on a content analysis of 91 wine labels. Considering the importance of this integrated communication, the purpose of this explorative analysis is to deduce implications that enable managers to master the use of this tool, exploiting all its potential

    Prediction of bench press performance in powerlifting: The role of upper limb anthropometry

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    The bench press (BP) is a complex, multiarticular exercise known as one of the three powerlifting specialties. Although several variables contribute to the maximum load lifted, upper limb variables may also play an important role in BP performance. In this study, a cohort of 47 male Italian classic powerlifters underwent a direct anthropometric evaluation during two official competitions. The recorded parameters included body mass index, body composition, and variables of the upper limb (indirectly evaluated cross-sectional areas and lengths). IPF-GL points and maximal strength (1RM) adjusted for weight were used as proxies for performance. Statistical comparisons between weaker and stronger powerlifters, Pearson correlation and partial correlation analyses, and multiple linear regression models were performed. The upper arm cross muscular area (r = 0.56) and fat-free mass (r = 0.31) were positively correlated with Wilks points, whereas the arm fat index was negatively correlated with 1RM BP (r = -0.37). Moreover, we proposed two new indices (UALR and UAMR) that represent the ratio between upper arm areas and length. Both univariate and multivariate analyses confirmed the strong association between these two variables and BP performance. Further improvement of this study may confirm the important role of body proportion and body composition as predictors of performance in strength sports
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