Damage accumulation in quasibrittle fracture

The strength of quasibrittle materials depends on the ensemble of defects inside the sample and on the way damage accumulates before failure. Using large-scale numerical simulations of the random fuse model, we investigate the evolution of the microcrack distribution as the applied load approaches the fracture point. We find that the distribution broadens mostly due to a tendency of cracks to coalesce in a way that increases with system size. We study how the observed behavior depends on the disorder present in the sample and relate the results with fracture size effects.Peer reviewe

Friction control with nematic lubricants via external fields

We study the connection between sliding friction and the phase behavior of a simple rigid bead-necklacemodel of a liquid crystal (LC) lubricant layer confined between two parallel plates. The dynamics is dependent on competing LC ordering mechanisms, including the direction of sliding, and an applied (electric) field. Together with temperature and an applied pressure, determining whether the lubricant is in a fluidlike isotropic state or in a layered in-plane nematic state, such ordering is found to control the frictional properties of the lubricant. Our extensive molecular dynamics simulations reveal in a detailed manner how friction can be controlled via applied fields. The results are expected to help in designing novel strategies to develop lubricants with dynamically controllable properties.Peer reviewe

Fracture Strength of Disordered Media: Universality, Interactions, and Tail Asymptotics

We study the asymptotic properties of fracture strength distributions of disordered elastic media by a combination of renormalization group, extreme value theory, and numerical simulation. We investigate the validity of the “weakest-link hypothesis” in the presence of realistic long-ranged interactions in the random fuse model. Numerical simulations indicate that the fracture strength is well-described by the Duxbury-Leath-Beale (DLB) distribution which is shown to flow asymptotically to the Gumbel distribution. We explore the relation between the extreme value distributions and the DLB-type asymptotic distributions and show that the universal extreme value forms may not be appropriate to describe the nonuniversal low-strength tail.Peer reviewe

Thoracoscopic epicardial pulmonary vein ablation for lone paroxysmal atrial fibrillation

Abstract Surgical treatment of atrial fibrillation recently gained new popularity since the introduction of different energy sources for ablative therapy as an alternative to the original ''cut-and-sew'' techniques. However, most of the cases have been performed together with other cardiac surgical procedures and mainly through a standard median sternotomy approach. We report here the first European case of closed-chest thoracoscopic pulmonary vein isolation in a patient with lone paroxysmal atrial fibrillation

Inflammation and frailty in the elderly: A systematic review and meta-analysis

The pathogenesis of frailty and the role of inflammation is poorly understood. We examined the evidence considering the relationship between inflammation and frailty through a systematic review and meta-analysis. A systematic literature search of papers providing data on inflammatory biomarkers and frailty was carried out in major electronic databases from inception until May 2016. From 1856 initial hits, 35 studies (32 cross-sectional studies n=3232 frail, n=11,483 pre-frail and n=8522 robust, and 563 pre-frail+robust; 3 longitudinal studies n=3402 participants without frailty at baseline) were meta-analyzed. Cross-sectional studies reported that compared to 6757 robust participants, both 1698 frail (SMD=1.00, 95%CI: 0.40-1.61) and 8568 pre-frail (SMD=0.33, 95%CI: 0.04-0.62) participants had significantly higher levels of C-reactive protein (CRP). Frailty (n=1057; SMD=1.12, 95%CI: 0.27-2.13) and pre-frailty (n=4467; SMD=0.56, 95%CI: 0.00-1.11) were associated with higher serum levels of interleukin-6 compared to people who were robust (n=2392). Frailty and pre-frailty were also significantly associated with elevated white blood cell and fibrinogen levels. In three longitudinal studies, higher serum CRP (OR=1.06, 95%CI: 0.78-1.44,) and IL-6 (OR=1.19, 95%CI: 0.87-1.62) were not associated with frailty. In conclusion, frailty and pre-frailty are associated with higher inflammatory parameters and in particular CRP and IL-6. Further longitudinal studies are needed

Risk of cardiovascular disease morbidity and mortality in frail and pre-frail older adults : Results from a meta-analysis and exploratory meta-regression analysis

Frailty is common and associated with poorer outcomes in the elderly, but its role as potential cardiovascular disease (CVD) risk factor requires clarification. We thus aimed to meta-analytically evaluate the evidence of frailty and pre-frailty as risk factors for CVD. Two reviewers selected all studies comparing data about CVD prevalence or incidence rates between frail/pre-frail vs. robust. The association between frailty status and CVD in cross-sectional studies was explored by calculating and pooling crude and adjusted odds ratios (ORs)+/- 95% confidence intervals (CIs); the data from longitudinal studies were pooled using the adjusted hazard ratios (HRs). Eighteen cohorts with a total of 31,343 participants were meta-analyzed. Using estimates from 10 cross-sectional cohorts, both frailty and pre-frailty were associated with higher odds of CVD than robust participants. Longitudinal data were obtained from 6 prospective cohort studies. After a median follow-up of 4.4 years, we identified an increased risk for faster onset of any type CVD in the frail (HR= 1.70 [95%CI, 1.18-2.45]; I-2 = 66%) and pre-frail (HR= 1.23 [95%CI, 1.07-1.36]; I-2 = 67%) vs. robust groups. Similar results were apparent for time to CVD mortality in the frail and pre-frail groups. In conclusion, frailty and pre-frailty constitute addressable and independent risk factors for CVD in older adults. (C) 2017 Elsevier B.V. All rights reserved.Peer reviewe

Monoclonal gammopathy of undetermined significance and bone health outcomes: a systematic review and exploratory meta-analysis

Monoclonal gammopathy of undetermined significance (MGUS) is a common condition in the elderly. A number of studies have investigated the relationship between MGUS and bone health outcomes including bone mineral density (BMD), osteoporosis and fractures, but no meta-analysis exists. We conducted a systematic review and exploratory meta-analysis comparing bone health outcomes in patients with MGUS. Two independent authors searched PubMed and Scopus from inception until 19 October 2016. A meta-analysis of cross-sectional and longitudinal studies investigating fractures and BMD was conducted. Standardised mean differences (SMD) ± 95% confidence intervals (CIs) were calculated for BMD, and risk ratios (RRs) were calculated for prevalent and incident fractures. Of 174 initial hits, 10 studies of moderate methodological quality were eligible, including 8711 individuals with MGUS vs. 52,865 controls. Compared to controls, subjects with MGUS showed significantly lower values for radial cortical volumetric BMD (1 study; SMD = -5.45, 95% CI: -7.24 to -3.66), but not at the lumbar spine, femoral neck or hip. The incidence of fractures was higher in people with MGUS (n = 7466) vs. controls (n = 52,304) (RR = 1.36, 95% CI 1.28-1.44, I 2 = 0%) over a median of 12.5-year follow-up. The incidence of vertebral fractures was particularly elevated (RR = 2.50, 95% CI 1.53-4.06) although limited to two studies. In conclusion, although with limitations, our preliminary meta-analysis suggests that patients with MGUS are at higher risk of fractures despite evidence for differences in BMD being equivocal. Future longitudinal research is required to confirm our findings and determine if fracture prevention interventions are warranted in people with MGUS

Weight loss is associated with improvements in cognitive function among overweight and obese people: a systematic review and meta-analysis

Whilst obesity is associated with a higher risk of cognitive impairment, the influence of weight loss on cognitive function in obese/overweight people is equivocal. We conducted a meta-analysis of randomized controlled trials (RCTs) and longitudinal studies evaluating the influence of voluntary weight loss on cognitive function in obese/overweight individuals. Articles were acquired from a systematic search of major databases from inception till 01/2016. A random effect meta-analysis of weight loss interventions (diet, physical activity, bariatric surgery) on different cognitive domains (memory, attention, executive functions, language and motor speed) was conducted. Twenty studies (13 longitudinal studies = 551 participants; 7 RCTs = 328 treated vs. 140 controls) were included. Weight loss was associated with a significant improvement in attention and memory in both longitudinal studies and RCTs, whereas executive function and language improved in longitudinal and RCT studies, respectively. In conclusion, intentional weight loss in obese/overweight people is associated with improvements in performance across various cognitive domains. Future adequately powered RCTs are required to confirm/refute these findings

Osteoarthritis and mortality: A prospective cohort study and systematic review with meta-analysis

Objectives: Osteoarthritis (OA) is a leading cause of disability, but the relationship with premature mortality remains uncertain. We aimed to investigate the relationship between OA and mortality from any cause and from cardiovascular disease (CVD). Methods: Electronic literature databases searches were conducted to identify prospective studies comparing mortality in a sample of people with and without OA. Risk of all-cause and CVD mortality were summarized using adjusted hazard ratios (HRs) for joint specific (hand, hip, and knee) and joint non-specific OA. New data from the Progetto Veneto Anziani (PRO.V.A.) study were also included. Results: From the PRO.V.A. study (N 1⁄4 2927), there was no significant increase in mortality risk for participants with any joint OA (N 1⁄4 1858) compared to non-OA (all-cause, HR 1⁄4 0.95, 95% CI: 0.77–1.15 and CVD, HR 1⁄4 1.12, 95% CI: 0.82–1.54). On meta-analysis, seven studies (OA 1⁄4 10,018/non-OA 1⁄4 18,541), with a median 12-year follow-up, reported no increased risk of any-cause mortality in those with OA (HR 1⁄4 1.10, 95% CI: 0.97–1.25). After removing data on hand OA, a significant association between OA and mortality was observed (HR 1⁄4 1.18, 95% CI: 1.08–1.28). There was a significant higher risk of overall mortality for (1) studies conducted in Europe, (2) patients with multi-joint OA; and (3) a radiological diagnosis of OA. OA was associated with significantly higher CVD mortality (HR 1⁄4 1.21, 95% CI: 1.10–1.34). Conclusions: People with OA are at increased risk of death due to CVD. The relationship with overall mortality is less clear and may be moderated by the presence of hand OA

Twelve Variants Polygenic Score for Low-Density Lipoprotein Cholesterol Distribution in a Large Cohort of Patients With Clinically Diagnosed Familial Hypercholesterolemia With or Without Causative Mutations

: Background A significant proportion of individuals clinically diagnosed with familial hypercholesterolemia (FH), but without any disease-causing mutation, are likely to have polygenic hypercholesterolemia. We evaluated the distribution of a polygenic risk score, consisting of 12 low-density lipoprotein cholesterol (LDL-C)-raising variants (polygenic LDL-C risk score), in subjects with a clinical diagnosis of FH. Methods and Results Within the Lipid Transport Disorders Italian Genetic Network (LIPIGEN) study, 875 patients who were FH-mutation positive (women, 54.75%; mean age, 42.47±15.00 years) and 644 patients who were FH-mutation negative (women, 54.21%; mean age, 49.73±13.54 years) were evaluated. Patients who were FH-mutation negative had lower mean levels of pretreatment LDL-C than patients who were FH-mutation positive (217.14±55.49 versus 270.52±68.59 mg/dL, P<0.0001). The mean value (±SD) of the polygenic LDL-C risk score was 1.00 (±0.18) in patients who were FH-mutation negative and 0.94 (±0.20) in patients who were FH-mutation positive (P<0.0001). In the receiver operating characteristic analysis, the area under the curve for recognizing subjects characterized by polygenic hypercholesterolemia was 0.59 (95% CI, 0.56-0.62), with sensitivity and specificity being 78% and 36%, respectively, at 0.905 as a cutoff value. Higher mean polygenic LDL-C risk score levels were observed among patients who were FH-mutation negative having pretreatment LDL-C levels in the range of 150 to 350 mg/dL (150-249 mg/dL: 1.01 versus 0.91, P<0.0001; 250-349 mg/dL: 1.02 versus 0.95, P=0.0001). A positive correlation between polygenic LDL-C risk score and pretreatment LDL-C levels was observed among patients with FH independently of the presence of causative mutations. Conclusions This analysis confirms the role of polymorphisms in modulating LDL-C levels, even in patients with genetically confirmed FH. More data are needed to support the use of the polygenic score in routine clinical practice