1,721,394 research outputs found
Detectability of the effect of inflationary non-Gaussianity on halo bias
No full textWe consider the description of the clustering of halos for physically motivated types of non-Gaussian initial conditions. In particular, we include non-Gaussianity of the type arising from single-field slow roll, multifields, curvaton (local type), higher-order derivative type (equilateral), vacuum-state modifications (enfolded type), and horizon-scale GR corrections type. We show that large-scale halo bias is a very sensitive tool for probing non-Gaussianity, potentially leading, for some planned surveys, to a detection of non-Gaussianity arising from horizon-scale GR corrections. In tandem with cosmic microwave background constraints, the halo bias approach can help enormously to discriminate among different shapes of non-Gaussianity and thus among models for the origin of cosmological perturbations
The effect of primordial non-Gaussianity onhalo bias
Full text linkIt has long been known how to analytically relate the clustering properties of the collapsed structures (halos) to those of the underlying dark matter distribution for Gaussian initial conditions. Here we apply the same approach to physically motivated non-Gaussian models. The techniques we use were developed in the 1980s to deal with the clustering of peaks of non-Gaussian density fields. The description of the clustering of halos for non-Gaussian initial conditions has recently received renewed interest, motivated by the forthcoming large galaxy and cluster surveys. For inflationary-motivated non-Gaussianities, we find an analytic expression for the halo bias as a function of scale, mass, and redshift, employing only the approximations of high peaks and large separations
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A software tool for robustness analysis in plant parameters space (ROBAN)
No full textThe modern control configurated vehicle (CCV) design technologies aims at taking simultaneously into account performances and maneuvrability requirements, and handling quality specifications. Therefore it is very important to provide the modern stability and control engineers with a tool which allows to determine the maximum allowable range of aircraft parameter variation according to handling quality requirements. In this paper some applications of the software ROBAN, developed at the Centro Italiano Ricerche Aerospaziali (CIRA), are illustrated. ROBAN has been developed to analyse stability and performances (in terms of eigenvalues location on the complex plane) of linear systems subject to uncertain parameters, and has been shown to be particularly useful to deal with the robustness problems which arise in the flight control field. In particular, after a description of the algorithm, the applications of ROBAN to analyse (a) Robustness in flight conditions, (b) Robustness against sensor failures, (c) Robustness with respect to PIO (pilot-induced oscillations) are discussed
A methodology for voice classification based on the personalized fundamental frequency estimation
No full textNowadays, the incidence of voice disorders is increasing rapidly, with about a third of the population suffering from dysphonia at some point in their lives. Dysphonia is a disorder that alters vocal quality and can impair and reduce the quality of life. The structural or functional alteration of the phonatory apparatus, unhealthy lifestyles or an excessive use of the vocal cords for work activities (e.g. teaching) can cause voice disorders. Unfortunately, people who suffer from dysphonia often underestimate its symptoms and therefore delay consulting a speech therapist for accurate voice assessment and treatment. Voice disorder evaluation involves a series of tests, including an acoustic analysis. This quantifies the measurements of voice quality through the evaluation of certain characteristic parameters, for example the fundamental frequency (F-0). In this paper, a personalized methodology for the estimation of the F-0 is presented. The personalization is accomplished by taking into account two of the main factors that influence the F-0, the gender and age of the subject. The estimation of the F-0 is crucial for the classification of the voice signal, because the discrimination of a healthy voice from a pathological one is achieved by evaluating the inclusion of the F-0 value within the healthy range. To evaluate the presented methodology, we have carried out a set of tests by using some voice signals selected from an available database in order to compare the classification ability of the proposed methodology with other algorithms existing in the literature. The numerical results obtained show that the proposed methodology provides a good accuracy, sensitivity, and specificity, respectively of over 77%, 72% and 81%, values better than those achieved by the most frequently other used and cited fundamental frequency estimation algorithms. Additionally, a statistical analysis to evaluate whether or not a statistically significant difference exists between the accuracy, sensitivity and specificity has been carried out. The outcome of the ANOVA tests and of the t-tests confirms that there is a significant difference between the proposed methodology and the other algorithms. Finally, the presented methodology could be embedded in a portable and simple m-health application that could be useful for the monitoring of the state of vocal health and the prevention of voice disorders. (C) 2018 Elsevier Ltd. All rights reserved
Biases from neutrino bias: To worry or not to worry?
No full textThe relation between the halo field and the matter fluctuations (halo bias), in the presence of massive neutrinos, depends on the total neutrino mass; massive neutrinos introduce an additional scale dependence of the bias that is usually neglected in cosmological analyses. We investigate the magnitude of the systematic effect on interesting cosmological parameters induced by neglecting this scale dependence, finding that while it is not a problem for current surveys, it is non-negligible for future, denser or deeper ones depending on the neutrino mass, the maximum scale used for the analyses, and the details of the nuisance parameters considered. However, there is a simple recipe to account for the bulk of the effect as to make it fully negligible, which we illustrate and advocate should be included in analysis of forthcoming large-scale structure surveys
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