Employing pre-stress to generate finite cloaks for antiplane elastic waves

It is shown that nonlinear elastic pre-stress of neo-Hookean hyperelastic materials can be used as a mechanism to generate finite cloaks and thus render objects near-invisible to incoming antiplane elastic waves. This approach appears to negate the requirement for special cloaking metamaterials with inhomogeneous and anisotropic material properties in this case. These properties are induced naturally by virtue of the pre-stress. This appears to provide a mechanism for broadband cloaking since dispersive effects due to metamaterial microstructure will not arise.Comment: 4 pages, 2 figure

Chronic Fatigue Syndrome and Chronic Widespread Pain in Adolescence:Population birth cohort study

Although many studies have investigated the overlap between pain phenotypes and chronic fatigue syndrome (CFS) in adults, little is known about the relationship between these conditions in adolescents. The study's aim was therefore to identify whether a relationship exists between chronic widespread pain (CWP) and CFS in adolescents and investigate whether the two share common associations with a set of covariates. A questionnaire was administered to offspring of the Avon Longitudinal Study of Parents and Children (ALSPAC) at age 17, asking about site, duration, and pain intensity, from which participants with CWP were identified. At the same research clinic, a computer-based Revised Clinical Interview Schedule was filled out, from which a classification of CFS was obtained. The relationship between selected covariates and CFS and CWP was investigated using a variety of logistic, ordinal logistic, and multinomial regressions. We identified 3,214 adolescents with complete data for all outcomes and covariates. There were 82 (2.6%) individuals classified as CFS and 145 (4.5%) as CWP. A classification of CFS resulted in an increased likelihood of having CWP (odds ratio = 3.87; 95% confidence interval, 2.05–7.31). Female adolescents were approximately twice as likely to have CFS or CWP, with multinomial regression revealing a greater sex effect for CWP compared with CFS. Those with exclusive CFS were more likely to report higher levels of pain and greater effect of pain compared with those without CFS, although associations attenuated to the null after adjustment for covariates, which did not occur in those with exclusive CWP. Multinomial regression revealed that relative to having neither CFS nor CWP, a 1-unit increase in the depression and anxiety scales increased the risk of having exclusive CFS and, to a greater extent, the risk of having comorbid CFS and CWP, but not exclusive CWP, which was only related to anxiety. PERSPECTIVE: In this cohort, 14.6% of adolescents with CFS have comorbid CWP. The likely greater proportion of more mild cases observed in this epidemiological study means that prevalence of overlap may be underestimated compared with those attending specialist services. Clinicians should be aware of the overlap between the 2 conditions and carefully consider treatment options offered

Achieving Very High PV Penetration

This article argues that optimally deployed intermittency solutions could affordably transform solar power generation into the firm power delivery system modern economies require, thereby enabling very high solar penetration and the displacement conventional power generation. The optimal deployment of these high‐penetration enabling solutions imply the existence of a healthy power grid, and therefore imply a central role for utilities and grid operators. This article also argues that a value‐based electricity compensation mechanism, recognizing the multifaceted, penetration‐dependent value and cost of solar energy, and capable of shaping consumption patterns to optimally match resource and demand, would be an effective vehicle to enable high solar penetration and deliver affordable firm power generation

Effect of Isoenergetic Substitution of Cheese with Other Dairy Products on Blood Lipid Markers in the Fasted and Postprandial State: An Updated and Extended Systematic Review and Meta-analysis of Randomized Controlled Trials in Adults

Consumption of fat as part of a cheese matrix may differentially affect blood lipid responses, when compared to other dairy foods. This systematic review was conducted to compare the impact of consuming equal amounts of fat from cheese and other dairy products on blood lipid markers in the fasted and postprandial state. Searches of PubMed (Medline), Cochrane Central and Embase databases were conducted up to mid-June 2022. Eligible human randomized controlled trials (RCTs) investigated the effect of isoenergetic substitution of hard or semi-hard cheese with other dairy products on blood lipid markers. Risk of bias was assessed using the Cochrane RoB 2.0 tool. Random-effects meta-analyses assessed the effect of ≥2 similar dietary replacements on the same blood lipid marker. Of 1,491 identified citations, 10 articles were included (risk of bias: all some concerns). Pooled analyses of 7 RCTs showed a reduction in fasting total cholesterol, LDL-cholesterol and HDL-cholesterol concentrations following ≥ 14 d mean daily intake of 135 g cheese (weighted mean difference (WMD): −0.24 mmol/L; 95% CI: −0.34, −0.15; I2 = 59.8 %, WMD: −0.19 mmol/L; 95% CI: −0.27, −0.12; I2 = 42.8%, and WMD: −0.04 mmol/L; 95% CI: −0.08, −0.00; I2 = 58.6%, respectively) relative to ∼52 g/d butter. We found no evidence of a benefit from replacing cheese for ≥ 14 d with milk on fasting blood lipid markers (n = 2). Limited postprandial RCTs, described in narrative syntheses, suggested that cheese-rich meals may induce differential fed-state lipid responses compared to some other dairy matrix structures, but not butter (n ≤ 2). In conclusion, these findings indicate that dairy fat consumed in the form of cheese has a differential effect on blood lipid responses relative to some other dairy food structures. However, owing to considerable heterogeneity and limited studies, further confirmation from RCTs is warranted. This systematic review protocol was registered at https://www.crd.york.ac.uk/PROSPERO/ as CRD42022299748

A Reusable Design for Precision Lunar Landing Systems

The top-level architecture to accomplish NASA's Vision for Space Exploration is to use Lunar missions and systems not just as an end in themselves, but also as testbeds for the more ambitious goals of Human Mars Exploration (HME). This approach means that Lunar missions and systems are most likely going to be targeted for (Lunar) polar missions, and also for long-duration (months) surface stays. This overacting theme creates basic top-level requirements for any next-generation lander system: 1) Long duration stays: a) Multiple landers in close proximity; b) Pinpoint landings for "surface rendezvous"; c) Autonomous landing of pre-positioned assets; and d) Autonomous Hazard Detection and Avoidance. 2) Polar and deep-crater landings (dark); 3) Common/extensible systems for Moon and Mars, crew and cargo. These requirements pose challenging technology and capability needs. Compare and contrast: 4) Apollo: a) 1 km landing accuracy; b) Lunar near-side (well imaged and direct-to-Earth com. possible); c) Lunar equatorial (landing trajectories offer best navigation support from Earth); d) Limited lighting conditions; e) Significant ground-in-the-loop operations; 5) Lunar Access: a) 10-100m landing precision; b) "Anywhere" access includes polar (potentially poor nav. support from Earth) and far side (poor gravity and imaging; no direct-to-Earth com); c) "Anytime" access includes any lighting condition (including dark); d) Full autonomous landing capability; e) Extensible design for tele-operation or operator-in-the-loop; and f) Minimal ground support to reduce operations costs. The Lunar Access program objectives, therefore, are to: a) Develop a baseline Lunar Precision Landing System (PLS) design to enable pinpoint "anywhere, anytime" landings; b) landing precision 10m-100m; c) Any LAT, LON; and d) Any lighting condition; This paper will characterize basic features of the next generation Lunar landing system, including trajectory types, sensor suite options and a reference system architecture

What I've Learned from E-Patients

Hoch and Ferguson discuss what they've learned from working with an online support group for people with epilepsy

Does moderate to vigorous physical activity mediate the association between depression and physical function in midlife: Evidence from two British birth cohort studies

BACKGROUND: Mental health and physical health are intrinsically linked, yet the mechanisms are not well understood. We investigated whether moderate-vigorous physical activity (MVPA) mediated the association between depression and physical function (PF) in midlife. METHODS: Individuals from two UK birth cohorts born within one week in 1958 (n = 7278) and 1970 (n = 6097) with data on depression (ages 33/34; Malaise Inventory), MVPA (age 42; self-reported) and PF (Short Form-36 subscale). Covariates included sex, childhood and adulthood social class, maternal mental health, childhood mood, alcohol consumption, smoking habits, sleep, marital status, BMI and long-standing illness/disability. Linear or multinomial logistic regression models examined associations between depression, MVPA and PF. We used a parametric g-computation mediation analysis approach to estimate percent differences in PF. RESULTS: Depression was associated with less frequent MVPA and poorer PF. Lower MVPA was associated with worse PF. The direct effect - randomised analogue not operating via MVPA - of depression on PF was -18.8 % (95%CI:--25.8,-11.8) and -15.8 % (20.6,-11.0) in the 1958 and 1970 cohorts, respectively. The indirect effect -operating via MVPA - was -0.5 % (-1.0,-0.03) and -0.2 % (-0.6, 0.3), resulting in a total proportion mediated of 3.1 % (0.1, 6.0) and 0.9 % (-1.6, 3.4). LIMITATIONS: MVPA was self-reported. Intermediate confounders and mediators were measured at the same age, however associations did not change in sensitivity analysis considering age 46 MVPA (1958 cohort). CONCLUSIONS: Although higher MVPA was protective against poor PF, there was only minor evidence that it mediated the association between depression and PF. Further investigation into other potential mediators of pathways from mental to physical health is needed

Stochastic model of randomly end-linked polymer network micro-regions

Polymerization and formation of crosslinked polymer networks are important processes in manufacturing, materials fabrication, and in the case of hydrated polymer networks, synthesis of biomedical materials, drug delivery, and tissue engineering. While considerable research has been devoted to the modeling of polymer networks to determine averaged, mean-field, global properties, there are fewer studies that specifically examine the variance of the composition across "micro-regions" (composed of a large, but finite, number of polymer network strands) within the larger polymer network.Here, we mathematically model the stochastic formation of polymer networks comprised of linear homobifunctional network strands that undergo an end-linking gelation process. We introduce a master equation that describes the evolution of the probabilities of possible network micro-region configurations as a function of time and extent of reaction. We specifically focus on the dynamics of network formation and the statistical variability of the gel micro-regions, particularly at intermediate extents of reaction. We also consider possible annealing effects and study how cooperative binding between the two end-groups on a single network-strand affects network formation. Our results allow for a more detailed and thorough understanding of polymer network dynamics and variability of network properties.Comment: 16 pages, 9 figure