1,721,000 research outputs found
From particle swarm optimization to consensus based optimization: stochastic modeling and mean-field limit
No full textIn this paper, we consider a continuous description based on stochastic differential equations of the popular particle swarm optimization (PSO) process for solving global optimization problems and derive in the large particle limit the corresponding mean-field approximation based on Vlasov-Fokker-Planck-type equations. The disadvantage of memory effects induced by the need to store the local best position is overcome by the introduction of an additional differential equation describing the evolution of the local best. A regularization process for the global best permits to formally derive the respective mean-field description. Subsequently, in the small inertia limit, we compute the related macroscopic hydrodynamic equations that clarify the link with the recently introduced consensus based optimization (CBO) methods. Several numerical examples illustrate the mean field process, the small inertia limit and the potential of this general class of global optimization method
Regression of benign melanocytic nevi ipilimumab-induced in an adult patient affected by metastatic melanoma: is it a sign of response to therapy?
No full textNessun
Incomplete excision of basal cell carcinoma of the head region: analysis of 724 consecutive cases
No full textBasal cell carcinoma (BCC) is the most frequent cutaneous malignancy in Caucasians, accounting for about 80% of all non-melanoma skin cancers.1Annual incidence of BCC is constantly increasing worldwide, by up to 10% per year, with a highest prevalence among elderly and males. In about 80% of cases BCC occurs on the head and neck area, in 15% of cases on the trunk, and more rarely on upper or lower limbs.
Complete surgical excision is the best of the therapeutic achievement in BCC treatment;3 however, radical excision is not always reached, especially when the head region is involved.
The present study aims to assess the rate of incomplete excision among all primary BCCs of head region consecutively excised in Clinic of Dermatology, University of Pavia, Italy in four years period, and to analyze some of the main clinical and surgical features/variables that may influence the incomplete resection
Peculiar hypertrichosis in a patient affected by Frontal fibrosing alopecia with pseudo "fringe sign"
Full text linkNo abstract available
Erythema ab igne induced by laptop computer: an emerging disease among adolescents?
No full textErythema ab igne (EAI) was a very common disease in the past, when it occurred mainly among people who worked with fire, or in people who had used heat sources in contact with the skin for warming purposes for long time. In the last decades, with the introduction of central heating in the buildings, EAI incidence was remarkably decreased in Western Countries, and it was found almost exclusively among elderly, and in people affected by defects in thermoregulation or alteration of periphery circulation. Recently, a new slight increase of EAI prevalence has been observed, although with some new features. Here, we describe three cases of adolescents who presented with brownish, reticulated patch on the anterior surface of their thighs. An accurate medical questioning revealed that the patients used to place the lower surface of laptop computer on the extensor side of their thighs in a cross-legged position for many hours (about 6-8 hours) every days. In particular, the patients supported the laptop computer always on the same leg. Laptop computer-induced EAI was diagnosed. Only a few cases of laptop computer-induced EAI have been reported in the literature. Although EAI is poorly symptomatic and it generally evolve to complete remission after an early discontinuance of heat source exposure, chronic lesions of EAI have been regarded as precancerous lesions. Therefore, it is important to implement diagnosis and prevention measures of this disease. Dermatologists should consider new causal agents for old diseases
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Consensus based optimization with memory effects: random selection and applications
Full text linkIn this work we extend the class of Consensus-Based Optimization (CBO)
metaheuristic methods by considering memory effects and a random selection
strategy. The proposed algorithm iteratively updates a population of particles
according to a consensus dynamics inspired by social interactions among
individuals. The consensus point is computed taking into account the past
positions of all particles. While sharing features with the popular Particle
Swarm Optimization (PSO) method, the exploratory behavior is fundamentally
different and allows better control over the convergence of the particle
system. We discuss some implementation aspects which lead to an increased
efficiency while preserving the success rate in the optimization process. In
particular, we show how employing a random selection strategy to discard
particles during the computation improves the overall performance. Several
benchmark problems and applications to image segmentation and Neural Networks
training are used to validate and test the proposed method. A theoretical
analysis allows to recover convergence guarantees under mild assumptions on the
objective function. This is done by first approximating the particles evolution
with a continuous-in-time dynamics, and then by taking the mean-field limit of
such dynamics. Convergence to a global minimizer is finally proved at the
mean-field level
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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