324 research outputs found

    Effects of concavity on the motion of a body immersed in a Vlasov gas

    Full text link
    We consider a body immersed in a perfect gas, moving under the action of a constant force EE along the x x axis . We assume the gas to be described by the mean-field approximation and interacting elastically with the body. Such a dynamic was studied in previous papers In these studies the asymptotic trend showed no sensitivity whatsoever to the shape of the object moving through the gas. In this work we investigate how a simple concavity in the shape of the body can affect its asymptotic behavior; we thus consider the case of hollow cylinder in three dimensions or a box-like body in two dimensions. We study the approach of the body velocity V(t)V (t) to the limiting velocity V∞V_{\infty} and prove that, under suitable smallness assumptions, the approach to equilibrium is ∣V∞−V(t)∣≈Ct−3| V_{\infty}-V(t)| \approx C t^{-3} both in two or three dimensions, being CC a positive constant. This approach is not exponential, as typical in friction problems, and even slower than for the simple disk and the convex body in R2 \mathbb{R}^2 or R3 \mathbb{R}^3

    Early-age strength measurement of shotcrete

    Get PDF
    Shotcrete or sprayed concrete is a special concrete designed for spraying onto a surface, as a construction material. With shotcrete application as a ground support system ever-present in both mining and tunnelling sectors, a major requirement of drive progression is to determine when it is safe to re-enter beneath freshly sprayed concrete. Accurately determining this time is of paramount importance. Generally, this re-entry time is based on measuring the developing strength of shotcrete until an adequate strength value is reached. The issue with current practice is that there is no widely accepted or generally preferred method that accurately assesses the shotcrete lining's true early-age strength. However, there are a number of strength tests that are commercially available and used in the industry, these include the soil penetrometer, needle penetrometer, bolt screws, beam end testers and drilled core samples. This paper researches into these testing methods and their characteristics in order to determine their accuracy, testing ranges and suitability for in situ use in the tunnelling and mining industry. The paper then looks into what advancements or developments in testing technology would be of benefit to the underground industries. The investigation ultimately reveals that current methods all have substantial shortcomings. Based on these findings, recommendations are proposed for the applicable use of the current testing methods and recommendations for future improvements

    How soil microbial biodiversity is modified by soil chemical parameters in differently managed olive orchards

    Get PDF
    Soil restoration is an important challenge of the 21st century, facing the increasing soil degradation, characterized by decline in quality and decrease in ecosystem goods and services. Several studies confirmed that sustainable orchard management practices might sequester atmospheric CO2 into soil, tree biomass and litter, enhancing soil organic carbon (SOC) stock and biodiversity. Higher biodiversity in ecosystems leads to greater stability and multifunctionality. In bacteria-plant interactions, both the bacteria and the plant profit from each other. These interactions play an important role in agriculture, positively affecting plant status and improving product quality. This study aimed at evaluating soil N/C parameters and microbial communities in soil, leaf (aerial part) and xylem sap between olive trees managed under sustainable practices for 17 years (i.e., no-tillage, drip irrigation with urban wastewater and recycling of polygenic carbon sources, like cover crops and pruning material) and trees managed under conventional ones (i.e., soil tillage, burning of pruning residues, mineral fertilization, rainfed), in a mature olive grove located in Southern Italy. In March 2017, samples of soil, leaf and xylem sap were collected in both treatments for DNA extraction and metagenomic analysis of the microbial communities. Soil samples were also collected for chemical and metabolic analyses. Results revealed that the long-term adoption of sustainable agricultural practices increased SOC, organic-N, and microbial biodiversity, with positive effects on plant growth protection and crop quality of olive plants

    Anomaly Detection for Skin Lesion Images Using Convolutional Neural Network and Injection of Handcrafted Features: A Method That Bypasses the Preprocessing of Dermoscopic Images

    Get PDF
    Skin cancer (SC) is one of the most common cancers in the world and is a leading cause of death in humans. Melanoma (M) is the most aggressive form of skin cancer and has an increasing incidence rate. Early and accurate diagnosis of M is critical to increase patient survival rates; however, its clinical evaluation is limited by the long timelines, variety of interpretations, and difficulty in distinguishing it from nevi (N) because of striking similarities. To overcome these problems and to support dermatologists, several machine-learning (ML) and deep-learning (DL) approaches have been developed. In the proposed work, melanoma detection, understood as an anomaly detection task with respect to the normal condition consisting of nevi, is performed with the help of a convolutional neural network (CNN) along with the handcrafted texture features of the dermoscopic images as additional input in the training phase. The aim is to evaluate whether the preprocessing and segmentation steps of dermoscopic images can be bypassed while maintaining high classification performance. Network training is performed on the ISIC2018 and ISIC2019 datasets, from which only melanomas and nevi are considered. The proposed network is compared with the most widely used pre-trained networks in the field of dermatology and shows better results in terms of classification and computational cost. It is also tested on the ISIC2016 dataset to provide a comparison with the literature: it achieves high performance in terms of accuracy, sensitivity, and specificity

    Androgen-deprivation therapy and SARS-Cov-2 infection: the potential double-face role of testosterone

    Get PDF
    To analyze possible effect of androgen deprivation therapy in preventing SARS-Cov-2 infection and respiratory complication

    Regional chromosomal localization of the human gene for galactose-1-phosphate uridyltransferase

    Full text link
    In the progeny of somatic cell hybrids formed by fusion of human lymphocytes and Chinese hamster mutant cells, a single human chromosome A2 was selectively retained when grown in appropriate medium.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47607/1/439_2004_Article_BF00393609.pd

    Characteristics of Sepsis or Acute Pyelonephritis Combined with Ureteral Stone in the United States: A Retrospective Analysis of Large National Cohort

    Get PDF
    To identify the characteristics of patients with sepsis or acute pyelonephritis (APN) combined with ureteral calculi and to analyze the risk factors in its causation. Methods: We included patients with sepsis or APN caused by ureteral calculi who received treatment in the United States from January 2003 to December 2017 using the Optum® deidentified Clinformatics® Datamart. Demographic factors and risk factors for the receipt of sepsis or APN were subsequently analyzed for statistical significance. Results: Of 467,502 urinary stone patients, age-matched multivariate analysis revealed that a history of urinary tract infection (OR 11.31, 95% CI 10.68–11.99, p < 0.0001) and female gender (OR 2.73, 95% CI 2.62–2.84, p < 0.0001) were significantly related to an increased risk of sepsis or APN. Conversely, a previous past medical history of urolithiasis (OR 0.91, 95% CI 0.87–0.95, p < 0.0001) and cancer (OR 0.91, 95% CI 0.87–0.95, p < 0.0001) were associated with a decreased risk of sepsis or APN. With regards to comorbidities, when more than one comorbidity was present, there was an additive effect with higher OR point estimates, rising to 11.31 (10.68–11.99) when three or more comorbidities present. History of urinary tract infection and female gender are risk factors for sepsis or APN in patients with ureteral calculi. Conclusions: This large national cohort reveals the characteristics of sepsis or APN combined with ureteral stone and provides an important baseline for the treatment of urolithiasis in the future

    Deep brain stimulation of the anterior nucleus of the thalamus in drug-resistant epilepsy in the MORE multicenter patient registry

    Get PDF
    Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (CC BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background and objectives: The efficacy of deep brain stimulation of the anterior nucleus of the thalamus (ANT DBS) in patients with drug-resistant epilepsy (DRE) was demonstrated in the double-blind Stimulation of the Anterior Nucleus of the Thalamus for Epilepsy randomized controlled trial. The Medtronic Registry for Epilepsy (MORE) aims to understand the safety and longer-term effectiveness of ANT DBS therapy in routine clinical practice. Methods: MORE is an observational registry collecting prospective and retrospective clinical data. Participants were at least 18 years old, with focal DRE recruited across 25 centers from 13 countries. They were followed for at least 2 years in terms of seizure frequency (SF), responder rate (RR), health-related quality of life (Quality of Life in Epilepsy Inventory 31), depression, and safety outcomes. Results: Of the 191 patients recruited, 170 (mean [SD] age of 35.6 [10.7] years, 43% female) were implanted with DBS therapy and met all eligibility criteria. At baseline, 38% of patients reported cognitive impairment. The median monthly SF decreased by 33.1% from 15.8 at baseline to 8.8 at 2 years (p 10 implantations) had 42.8% reduction in median monthly SF by 2 years in comparison with 25.8% in low-volume center. In patients with cognitive impairment, the reduction in median monthly SF was 26.0% by 2 years compared with 36.1% in patients without cognitive impairment. The most frequently reported adverse events were changes (e.g., increased frequency/severity) in seizure (16%), memory impairment (patient-reported complaint, 15%), depressive mood (patient-reported complaint, 13%), and epilepsy (12%). One definite sudden unexpected death in epilepsy case was reported. Discussion: The MORE registry supports the effectiveness and safety of ANT DBS therapy in a real-world setting in the 2 years following implantation. Classification of evidence: This study provides Class IV evidence that ANT DBS reduces the frequency of seizures in patients with drug-resistant focal epilepsy.The MORE registry was sponsored and funded by Medtronic, plc.info:eu-repo/semantics/publishedVersio
    • …
    corecore