530 research outputs found

    Evolution of a double-front Rayleigh-Taylor system using a GPU-based high resolution thermal Lattice-Boltzmann model

    Full text link
    We study the turbulent evolution originated from a system subjected to a Rayleigh-Taylor instability with a double density at high resolution in a 2 dimensional geometry using a highly optimized thermal Lattice Boltzmann code for GPUs. The novelty of our investigation stems from the initial condition, given by the superposition of three layers with three different densities, leading to the development of two Rayleigh-Taylor fronts that expand upward and downward and collide in the middle of the cell. By using high resolution numerical data we highlight the effects induced by the collision of the two turbulent fronts in the long time asymptotic regime. We also provide details on the optimized Lattice-Boltzmann code that we have run on a cluster of GPU

    MM Algorithms for Minimizing Nonsmoothly Penalized Objective Functions

    Full text link
    In this paper, we propose a general class of algorithms for optimizing an extensive variety of nonsmoothly penalized objective functions that satisfy certain regularity conditions. The proposed framework utilizes the majorization-minimization (MM) algorithm as its core optimization engine. The resulting algorithms rely on iterated soft-thresholding, implemented componentwise, allowing for fast, stable updating that avoids the need for any high-dimensional matrix inversion. We establish a local convergence theory for this class of algorithms under weaker assumptions than previously considered in the statistical literature. We also demonstrate the exceptional effectiveness of new acceleration methods, originally proposed for the EM algorithm, in this class of problems. Simulation results and a microarray data example are provided to demonstrate the algorithm's capabilities and versatility.Comment: A revised version of this paper has been published in the Electronic Journal of Statistic

    Herbal highs: review on psychoactive effects and neuropharmacology

    Get PDF
    Background: A new trend among users of new psychoactive substances’ the consumption of “herbal highs”: plant parts containing psychoactive substances. Most of the substances extracted from herbs, in old centuries were at the centre of religious ceremonies of ancient civilizations. Currently, these herbal products are mainly sold by internet web sites and easily obtained since some of them have no legal restriction. Objective: We reviewed psychoactive effects and neuropharmacology of the most used “herbal highs” with characterized active principles, with studies reporting mechanisms of action, pharmacological and subjective effects, eventual secondary effects including intoxications and/or fatalities Method: The PubMed database was searched using the following key.words: herbal highs, Argyreia nervosa, Ipomoea violacea and Rivea corymbosa; Catha edulis; Datura stramonium; Piper methysticum; Mitragyna speciosa. Results: Psychoactive plants here reviewed have been known and used from ancient times, even if for some of them limited information still exist regarding subjective and neuropharmacological effects and consequent eventual toxicity when plants are used alone or in combination with “classical” drugs of abuse. Conclusion: Some “herbal highs” should be classified as harmful drugs since chronic administration has been linked with addiction and cognitive impairment; for some others taking into consideration only the recent trends of abuse, studies investigating these aspects are lacking

    Review of deaths related to taking ecstasy, England and Wales, 1997-2000

    Get PDF
    Original article can be found at: http://www.bmj.com/archive/--Copyright BMJ Publishing Group Ltd DOI : 10.1136/bmj.326.7380.80Peer reviewe

    Matched filters for coalescing binaries detection on massively parallel computers

    Get PDF
    We discuss some computational problems associated to matched filtering of experimental signals from gravitational wave interferometric detectors in a parallel-processing environment. We then specialize our discussion to the use of the APEmille and apeNEXT processors for this task. Finally, we accurately estimate the performance of an APEmille system on a computational load appropriate for the LIGO and VIRGO experiments, and extrapolate our results to apeNEXT.Comment: 19 pages, 6 figure

    A combined proteomics, metabolomics and in vivo analysis approach for the characterization of probiotics in large-scale production

    Get PDF
    The manufacturing processes of commercial probiotic strains may be affected in different ways in the attempt to optimize yield, costs, functionality, or stability, influencing gene expression, protein patterns, or metabolic output. Aim of this work is to compare different samples of a high concentration (450 billion bacteria) multispecies (8 strains) formulation produced at two different manufacturing sites, United States of America (US) and Italy (IT), by applying a combination of functional proteomics, metabolomics, and in vivo analyses. Several protein-profile differences were detected between IT-and US-made products, with Lactobacillus paracasei, Streptococcus thermophilus, and Bifidobacteria being the main affected probiotics/microorganisms. Performing proton nuclear magnetic spectroscopy (1H-NMR), some discrepancies in amino acid, lactate, betaine and sucrose concentrations were also reported between the two products. Finally, we investigated the health-promoting and antiaging effects of both products in the model organism Caenorhabditis elegans. The integration of omics platforms with in vivo analysis has emerged as a powerful tool to assess manufacturing procedures

    Il Sistema di Gestione della Sicurezza sul Lavoro (SGSL) sul modello UNI-INAIL ed il Safety Management System (SMS) in ambito aeroportuale a confronto.

    Get PDF
    In seguito all’emanazione del Decreto Legislativo n. 81 del 9 aprile 2008, l’adozione di un ’SGSL rappresenta una notevole opportunità per le aziende in termini di gestione e contenimento dei rischi aziendali Il presente lavoro analizza e mette a confronto due sistemi di gestione, il Safety Management System, che risponde ad una norma cogente imposta dall’Enac per le società di gestione aeroportuali, ed il Sistema di Gestione della salute e Sicurezza sul Lavoro sul modello delle linee guida UNI-INAIL, mettendo in risalto i diversi punti in comune e i margini di miglioramento di entrambi. Le differenze principali tra i due sistemi risiedono nell’obiettivo che si prefiggono di raggiungere, nell’approccio alla definizione della politica e degli obiettivi. L’obiettivo che l’SMS si prefigge è analizzare e modificare le attività lavorative al fine di assicurare principalmente l’incolumità degli utenti coinvolti nelle operazioni aeroportuali, mentre il SGSL mira a definire un sistema di gestione orientato alla sicurezza sul lavoro. Nel presente studio si giunge alla conclusione che i due sistemi potrebbero essere integrati all’interno di realtà aziendali quali società di gestione aeroportuali, compagnie aeree o aziende a rischio di incidente rilevante. Dal confronto visto emerge una proposta: nella prospettiva di emettere una norma certificabile da parte di un ente accreditato, perché non integrare le due linee guida anche alla luce delle esperienze positive acquisita in questi anni di sperimentazione

    GLP-1 Receptor Agonists and Related Mental Health Issues; Insights from a Range of Social Media Platforms Using a Mixed-Methods Approach

    Get PDF
    © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/The emergence of glucagon-like peptide-1 receptor agonists (GLP-1 RAs; semaglutide and others) now promises effective, non-invasive treatment of obesity for individuals with and without diabetes. Social media platforms’ users started promoting semaglutide/Ozempic as a weight-loss treatment, and the associated increase in demand has contributed to an ongoing worldwide shortage of the drug associated with levels of non-prescribed semaglutide intake. Furthermore, recent reports emphasized some GLP-1 RA-associated risks of triggering depression and suicidal thoughts. Consistent with the above, we aimed to assess the possible impact of GLP-1 RAs on mental health as being perceived and discussed in popular open platforms with the help of a mixed-methods approach. Reddit posts yielded 12,136 comments, YouTube videos 14,515, and TikTok videos 17,059, respectively. Out of these posts/entries, most represented matches related to sleep-related issues, including insomnia (n = 620 matches); anxiety (n = 353); depression (n = 204); and mental health issues in general (n = 165). After the initiation of GLP-1 RAs, losing weight was associated with either a marked improvement or, in some cases, a deterioration, in mood; increase/decrease in anxiety/insomnia; and better control of a range of addictive behaviors. The challenges of accessing these medications were a hot topic as well. To the best of our knowledge, this is the first study documenting if and how GLP-1 RAs are perceived as affecting mood, mental health, and behaviors. Establishing a clear cause-and-effect link between metabolic diseases, depression and medications is difficult because of their possible reciprocal relationship, shared underlying mechanisms and individual differences. Further research is needed to better understand the safety profile of these molecules and their putative impact on behavioral and non-behavioral addictions.Peer reviewe
    • …
    corecore