A Fast Active Set Block Coordinate Descent Algorithm for ℓ1\ell_1-regularized least squares

The problem of finding sparse solutions to underdetermined systems of linear equations arises in several applications (e.g. signal and image processing, compressive sensing, statistical inference). A standard tool for dealing with sparse recovery is the $\ell_1$-regularized least-squares approach that has been recently attracting the attention of many researchers. In this paper, we describe an active set estimate (i.e. an estimate of the indices of the zero variables in the optimal solution) for the considered problem that tries to quickly identify as many active variables as possible at a given point, while guaranteeing that some approximate optimality conditions are satisfied. A relevant feature of the estimate is that it gives a significant reduction of the objective function when setting to zero all those variables estimated active. This enables to easily embed it into a given globally converging algorithmic framework. In particular, we include our estimate into a block coordinate descent algorithm for $\ell_1$-regularized least squares, analyze the convergence properties of this new active set method, and prove that its basic version converges with linear rate. Finally, we report some numerical results showing the effectiveness of the approach.Comment: 28 pages, 5 figure

Legittimazione processuale in materia di " zonizzazione acustica "

Risulta possibile, in nome del principio di sussidiarietà orizzontale, estendere la legittimazione ad agire anche ad enti non iscritti nell ' apposito elenco ministeriale ai sensi della legge

La Casa delle Donne di Ravenna: contro i muri della discriminazione

Dopo l’approvazione del Regolamento per la cura e la rigenerazione dei beni comuni urbani, il Comune ravennate arricchisce il suo corredo di esperienze di amministrazione condivisa con un nuovo patto di collaborazione, stipulato con l’associazione Liberedonne e volto alla gestione condivisa delle attività promosse nell’ambito della Casa delle donne di Ravenna

Pluralism at Risk? Heterodox Economic Approaches and the Evaluation of Economic Research in Italy

We analyze Italy's recent research evaluation exercise (VTR) as a salient example in discussing some internationally relevant issues emerging from the evaluation of research in economics. We claim that evaluation and its criteria, together with its linkage to research institutions' financing, are likely to affect the direction of research in a problematic way. As the Italian case documents, it is specifically economists who adopt unorthodox paradigms or pursue less diffused topics of research that should be concerned about research evaluation and its criteria. After outlining the recent practice of economic research in Italy and highlighting the relevant scope for pluralism that traditionally characterizes it, we analyze the publications submitted for evaluation to the VTR. By comparing these publications to all the entries in the EconLit database authored by economists located in Italy, we find a risk that the adopted ranking criteria may lead to disregarding historical methods in favor of quantitative and econometric methods, and heterodox schools in favor of mainstream approaches. Finally, by summarizing the current debate in Italy, we claim that evaluation should not be refused by heterodox economists, but rather that a reflection on the criteria of evaluation should be put forward at an international level in order to establish fair competition among research paradigms, thus, preserving pluralism in the discipline. © 2010 American Journal of Economics and Sociology, Inc

The complexity of neuroenhancement and the adoption of a social cognitive perspective

This contribution attempts to provide a broad perspective to the psychological study of neuroenhancement (NE). It departs from the assumption that, as the use of performance enhancing substances in sport, the use of substances with the aim of improving one’s cognitive, motivational and affective functioning in academic domains is a goal-directed behavior. As such, its scientific study may very well benefit from an analysis taking into account the psychological processes regulating people’s behavioral intentions and decisions. Within this broad framework, this contribution addresses several issues that currently seem to characterize the debate in the literature on neuroenhancement substances (NES) use. The first conceptual issue seeks to determine and define the “boundaries” of the phenomenon. The second issue concerns the empirical evidence on the prevalence of using certain substances for the purpose of NE. Finally, there is a debate around the ethical and moral implications of NE. Along these lines, the existing psychological research on NE has adopted mainly sociological and economic decision-making perspectives, greatly contributing to the psychological discourse about the phenomenon of NE. However, we argue that the existing psychological literature does not offer a common, explicit and integrated theoretical framework. Borrowing from the framework of doping research, we recommend the adoption of a social cognitive model for pursuing a systematic analysis of the psychological processes that dynamically regulate students’ use of NES over tim

Presence of multiple bacterial markers in clinical samples might be useful for presumptive diagnosis of infection in cirrhotic patients with culture-negative reports

Bacterial infections in cirrhotic patients with ascites are associated with a severe prognosis and an increased risk of death. The microbiological standard tests for the diagnosis of suspected infection, based on culture test of blood and ascitic fluid, are, in many cases (30-40 %), negative, even when patients show symptoms of infection. A multiple culture-independent protocol was applied and evaluated as a diagnostic and prognostic tool for the detection of bacterial infection in cirrhotic patients. Sixty-four culture-negative samples obtained from 34 cirrhotic patients, with PMN < 250 cells/μl of ascitic fluid, were screened for the presence of bacterial DNA, endotoxin, peptidoglycan/β-glucan and microscopically visible bacterial cells. Correlations between the presence of multiple markers and various clinical and laboratory parameters were evaluated. Bacterial DNA was detected in 23 samples collected from 16 patients; a large part of these samples also showed the presence of other bacterial markers, which was associated with a worsening of liver functionality, a higher incidence of infections during the follow-up and a higher mortality rate in our cohort of cirrhotic patients. We believe that the detection of additional bacterial markers in bacterial DNA-positive clinical samples makes the bacterial presence and its clinical significance more realistic and might be useful as early markers of an ongoing bacterial infection and in establishing a clinical prognosis

A nonmonotone GRASP

A greedy randomized adaptive search procedure (GRASP) is an itera- tive multistart metaheuristic for difficult combinatorial optimization problems. Each GRASP iteration consists of two phases: a construction phase, in which a feasible solution is produced, and a local search phase, in which a local optimum in the neighborhood of the constructed solution is sought. Repeated applications of the con- struction procedure yields different starting solutions for the local search and the best overall solution is kept as the result. The GRASP local search applies iterative improvement until a locally optimal solution is found. During this phase, starting from the current solution an improving neighbor solution is accepted and considered as the new current solution. In this paper, we propose a variant of the GRASP framework that uses a new “nonmonotone” strategy to explore the neighborhood of the current solu- tion. We formally state the convergence of the nonmonotone local search to a locally optimal solution and illustrate the effectiveness of the resulting Nonmonotone GRASP on three classical hard combinatorial optimization problems: the maximum cut prob- lem (MAX-CUT), the weighted maximum satisfiability problem (MAX-SAT), and the quadratic assignment problem (QAP)

On global minimizers of quadratic functions with cubic regularization

In this paper, we analyze some theoretical properties of the problem of minimizing a quadratic function with a cubic regularization term, arising in many methods for unconstrained and constrained optimization that have been proposed in the last years. First we show that, given any stationary point that is not a global solution, it is possible to compute, in closed form, a new point with a smaller objective function value. Then, we prove that a global minimizer can be obtained by computing a finite number of stationary points. Finally, we extend these results to the case where stationary conditions are approximately satisfied, discussing some possible algorithmic applications.Comment: Optimization Letters (2018

Indicators of distress in newly diagnosed breast cancer patients

Background. The diagnosis, treatment, and long-term management of cancer can present individuals with a multitude of stressors at various points in that trajectory. Psychosocial distress may appear early in the diagnostic process and have negative effects on compliance with treatment and subsequent quality of life. Purpose. The aim of the study was to determine early-phase predictors of distress before any medical treatment. Method. Consistent with the goals of the study, 123 newly diagnosed breast cancer patients (20 to 74 years old) completed multiple indicators of knowledge about breast cancer management and treatment, attitudes toward cancer, social support, coping efficacy, and distress. Results. SEM analysis confirmed the hypothesized model. Age was negatively associated with the patient’s knowledge (β = − 0.22), which, in turn, was positively associated with both attitudes toward breast cancer (β = 0.39) and coping self-efficacy (β = 0.36). Self-efficacy was then directly related to psychological distress (β = − 0.68). Conclusions. These findings establish indicators of distress in patients early in the cancer trajectory. From a practical perspective, our results have implications for screening for distress and for the development of early interventions that may be followed by healthcare professionals to reduce psychological distres

Rimuovere i tappi al fluire della conoscenza psicologica migliorando la formazione post-laurea e favorendo il dialogo tra ricerca e professione

Pur senza dimenticare i temi relativi alle politiche universitarie e mantenendo ferma la centralità della attenzione alla valorizzazione della qualità della ricerca psicologica l’AIP, nel triennio che va concludendosi ha cercato con convinzione di intraprendere un percorso di testimonianza del valore sociale delle conoscenze psicologiche, aprendosi al dialogo con le istituzioni politiche nazionali e locali, aprendo dibattiti pubblici sui temi della scuola, del lavoro, della salute, dell’impatto delle nuove tecnologi