Dynamic Failure in Amorphous Solids via a Cavitation Instability

The understanding of dynamic failure in amorphous materials via the propagation of free boundaries like cracks and voids must go beyond elasticity theory, since plasticity intervenes in a crucial and poorly understood manner near the moving free boundary. In this Letter we focus on failure via a cavitation instability in a radially-symmetric stressed material, set up the free boundary dynamics taking both elasticity and visco-plasticity into account, using the recently proposed athermal Shear Transformation Zone theory. We demonstrate the existence (in amorphous systems) of fast cavitation modes accompanied by extensive plastic deformations and discuss the revealed physics.Comment: 4 pages, 4 figure

Free-Boundary Dynamics in Elasto-plastic Amorphous Solids: The Circular Hole Problem

We develop an athermal shear-transformation-zone (STZ) theory of plastic deformation in spatially inhomogeneous, amorphous solids. Our ultimate goal is to describe the dynamics of the boundaries of voids or cracks in such systems when they are subjected to remote, time-dependent tractions. The theory is illustrated here for the case of a circular hole in an infinite two-dimensional plate, a highly symmetric situation that allows us to solve much of the problem analytically. In spite of its special symmetry, this example contains many general features of systems in which stress is concentrated near free boundaries and deforms them irreversibly. We depart from conventional treatments of such problems in two ways. First, the STZ analysis allows us to keep track of spatially heterogeneous, internal state variables such as the effective disorder temperature, which determines plastic response to subsequent loading. Second, we subject the system to stress pulses of finite duration, and therefore are able to observe elasto-plastic response during both loading and unloading. We compute the final deformations and residual stresses produced by these stress pulses. Looking toward more general applications of these results, we examine the possibility of constructing a boundary-layer theory that might be useful in less symmetric situations.Comment: 30 pages (preprint format), 9 figure

Reconstruction and thermal stability of the cubic SiC(001) surfaces

The (001) surfaces of cubic SiC were investigated with ab-initio molecular dynamics simulations. We show that C-terminated surfaces can have different c(2x2) and p(2x1) reconstructions, depending on preparation conditions and thermal treatment, and we suggest experimental probes to identify the various reconstructed geometries. Furthermore we show that Si-terminated surfaces exhibit a p(2x1) reconstruction at T=0, whereas above room temperature they oscillate between a dimer row and an ideal geometry below 500 K, and sample several patterns including a c(4x2) above 500 K.Comment: 12 pages, RevTeX, figures 1 and 2 available in gif form at http://irrmawww.epfl.ch/fg/sic/fig1.gif and http://irrmawww.epfl.ch/fg/sic/fig2.gi

Developing community-based preventive interventions in Hong Kong: a description of the first phase of the family project

<p>Abstract</p> <p>Background</p> <p>This paper describes the development of culturally-appropriate family-based interventions and their relevant measures, to promote family health, happiness and harmony in Hong Kong. Programs were developed in the community, using a collaborative approach with community partners. The development process, challenges, and the lessons learned are described. This experience may be of interest to the scientific community as there is little information currently available about community-based development of brief interventions with local validity in cultures outside the West.</p> <p>Methods</p> <p>The academic-community collaborative team each brought strengths to the development process and determined the targets for intervention (parent-child relationships). Information from expert advisors and stakeholder discussion groups was collected and utilized to define the sources of stress in parent-child relationships.</p> <p>Results</p> <p>Themes emerged from the literature and discussion groups that guided the content of the intervention. Projects emphasized features that were appropriate for this cultural group and promoted potential for sustainability, so that the programs might eventually be implemented at a population-wide level. Challenges included ensuring local direction, relevance and acceptability for the intervention content, engaging participants and enhancing motivation to make behavior changes after a brief program, measurement of behavior changes, and developing an equal partner relationship between academic and community staff.</p> <p>Conclusions</p> <p>This work has public health significance because of the global importance of parent-child relationships as a risk-factor for many outcomes in adulthood, the need to develop interventions with strong evidence of effectiveness to populations outside the West, the potential application of our interventions to universal populations, and characteristics of the interventions that promote dissemination, including minimal additional costs for delivery by community agencies, and high acceptability to participants.</p

Predictors of allergen sensitization in Singapore children from birth to 3 years

10.1186/s13223-016-0161-xAllergy, asthma, and clinical immunology : official journal of the Canadian Society of Allergy and Clinical Immunology121Article number 56GUSTO (Growing up towards Healthy Outcomes

Policy and prevention approaches for disordered and hazardous gaming and internet use: an international perspective

Problems related to high levels of gaming and Internet usage are increasingly recognized as a potential public health burden across the developed world. The aim of this review was to present an international perspective on prevention strategies for Internet gaming disorder and related health conditions (e.g., Internet addiction), as well as hazardous gaming and Internet use. A systematic review of quantitative research evidence was conducted, followed by a search of governmental reports, policy and position statements, and health guidelines in the last decade. The regional scope included the United States, United Kingdom, Australia, China, Germany, Japan, and South Korea. Prevention studies have mainly involved school-based programs to train healthier Internet use habits in adolescents. The efficacy of selective prevention is promising but warrants further empirical attention. On an international scale, the formal recognition of gaming or Internet use as a disorder or as having quantifiable harms at certain levels of usage has been foundational to developing structured prevention responses. The South Korean model, in particular, is an exemplar of a coordinated response to a public health threat, with extensive government initiatives and long-term strategic plans at all three levels of prevention (i.e., universal, selective, and indicated). Western regions, by comparison, are dominated by prevention approaches led by non-profit organizations and private enterprise. The future of prevention of gaming and Internet problems ultimately relies upon all stakeholders working collaboratively in the public interest, confronting the reality of the evidence base and developing practical, ethical, and sustainable countermeasures

School-based prevention for adolescent Internet addiction: prevention is the key. A systematic literature review

Adolescents’ media use represents a normative need for information, communication, recreation and functionality, yet problematic Internet use has increased. Given the arguably alarming prevalence rates worldwide and the increasingly problematic use of gaming and social media, the need for an integration of prevention efforts appears to be timely. The aim of this systematic literature review is (i) to identify school-based prevention programmes or protocols for Internet Addiction targeting adolescents within the school context and to examine the programmes’ effectiveness, and (ii) to highlight strengths, limitations, and best practices to inform the design of new initiatives, by capitalizing on these studies’ recommendations. The findings of the reviewed studies to date presented mixed outcomes and are in need of further empirical evidence. The current review identified the following needs to be addressed in future designs to: (i) define the clinical status of Internet Addiction more precisely, (ii) use more current psychometrically robust assessment tools for the measurement of effectiveness (based on the most recent empirical developments), (iii) reconsider the main outcome of Internet time reduction as it appears to be problematic, (iv) build methodologically sound evidence-based prevention programmes, (v) focus on skill enhancement and the use of protective and harm-reducing factors, and (vi) include IA as one of the risk behaviours in multi-risk behaviour interventions. These appear to be crucial factors in addressing future research designs and the formulation of new prevention initiatives. Validated findings could then inform promising strategies for IA and gaming prevention in public policy and education

Efficacy and safety of bempedoic acid for the treatment of hypercholesterolemia: A systematic review and meta-analysis

Background Bempedoic acid is a first-in-class lipid-lowering drug recommended by guidelines for the treatment of hypercholesterolemia. Our objective was to estimate its average effect on plasma lipids in humans and its safety profile. Methods and findings We carried out a systematic review and meta-analysis of phase II and III randomized controlled trials on bempedoic acid (PROSPERO: CRD42019129687). PubMed (Medline), Scopus, Google Scholar, and Web of Science databases were searched, with no language restriction, from inception to 5 August 2019. We included 10 RCTs (n = 3,788) comprising 26 arms (active arm [n = 2,460]; control arm [n = 1,328]). Effect sizes for changes in lipids and high-sensitivity C-reactive protein (hsCRP) serum concentration were expressed as mean differences (MDs) and 95% confidence intervals (CIs). For safety analyses, odds ratios (ORs) and 95% CIs were calculated using the Mantel–Haenszel method. Bempedoic acid significantly reduced total cholesterol (MD −14.94%; 95% CI −17.31%, −12.57%; p &lt; 0.001), non-high-density lipoprotein cholesterol (MD −18.17%; 95% CI −21.14%, −15.19%; p &lt; 0.001), low-density lipoprotein cholesterol (MD −22.94%; 95% CI −26.63%, −19.25%; p &lt; 0.001), low-density lipoprotein particle number (MD −20.67%; 95% CI −23.84%, −17.48%; p &lt; 0.001), apolipoprotein B (MD −15.18%; 95% CI −17.41%, −12.95%; p &lt; 0.001), high-density lipoprotein cholesterol (MD −5.83%; 95% CI −6.14%, −5.52%; p &lt; 0.001), high-density lipoprotein particle number (MD −3.21%; 95% CI −6.40%, −0.02%; p = 0.049), and hsCRP (MD −27.03%; 95% CI −31.42%, −22.64%; p &lt; 0.001). Bempedoic acid did not significantly modify triglyceride level (MD −1.51%; 95% CI −3.75%, 0.74%; p = 0.189), verylow-density lipoprotein particle number (MD 3.79%; 95% CI −9.81%, 17.39%; p = 0.585), and apolipoprotein A-1 (MD −1.83%; 95% CI −5.23%, 1.56%; p = 0.290). Treatment with bempedoic acid was positively associated with an increased risk of discontinuation of treatment (OR 1.37; 95% CI 1.06, 1.76; p = 0.015), elevated serum uric acid (OR 3.55; 95% CI 1.03, 12.27; p = 0.045), elevated liver enzymes (OR 4.28; 95% CI 1.34, 13.71; p = 0.014), and elevated creatine kinase (OR 3.79; 95% CI 1.06, 13.51; p = 0.04), though it was strongly associated with a decreased risk of new onset or worsening diabetes (OR 0.59; 95% CI 0.39, 0.90; p = 0.01). The main limitation of this meta-analysis is related to the relatively small number of individuals involved in the studies, which were often short or middle term in length. Conclusions Our results show that bempedoic acid has favorable effects on lipid profile and hsCRP levels and an acceptable safety profile. Further well-designed studies are needed to explore its longer-term safety