Quantum friction in the presence of a perfectly conducting plate

A neutral but polarizable particle at rest near a perfectly conducting plate feels a force normal to the surface of the plate, which tends to pull the particle towards the plate. This is the well-known Casimir-Polder force, which has long been theoretically proposed and experimentally observed. In this paper, we explore the transverse frictional force on an atom moving uniformly parallel to a perfectly conducting plate. Although many theoretical predictions can be found for the quantum friction on a particle moving above an imperfect surface, the extreme situation with a perfectly conducting plate seems to have been largely ignored by the theoretical community. We investigate this ideal case as a natural extension of our previous works on quantum vacuum friction (blackbody friction), and conclude that there does exist a quantum frictional force on an atom moving above a perfectly conducting plate. Very interestingly, the distance dependence, the temperature dependence and even the sign of the frictional force can depend on the polarization state of the atom. For an isotropic atom with a static polarizability, the resultant frictional force is found to be negative definite and therefore remains a true drag. Just above the surface of the plate, the magnitude of the frictional force is twice that of the quantum vacuum friction in the absence of the plate

Circadian Synchrony between Mothers and Young in the European Rabbit: Or Not? A Cautionary Tale

The European rabbit Oryctolagus cuniculus, ancestor of all domestic breeds, has an unusual pattern of maternal care in which females briefly nurse their young just once approximately every 24 h, and where the pups anticipate and prepare for their mother’s arrival. Chronobiologists have seen this as a model mammalian system to study the physiological and neurobiological underpinnings of a biologically relevant circadian complex. However, observations of nursing in wild rabbits, together with studies of nursing in domestic breeds allowed free access to their young in laboratory settings, suggest that the rabbit’s pattern of daily nursing visits resembles an hourglass rather than a circadian process, well suited to the sudden starts and stops of natural nursing cycles. We consider whether there might be other such cases in the literature, including in human chronobiology, in which failing to consider the organism’s natural, evolved daily patterns of behaviour and prematurely studying these under artificially imposed laboratory time schedules might have also led to such patterns being erroneously considered circadian

Vacuum torque, propulsive forces, and anomalous tangential forces: Effects of nonreciprocal media out of thermal equilibrium

From the generalized fluctuation-dissipation theorem, it is known that a body at rest made of nonreciprocal material may experience a torque, even in vacuum, if it is not in thermal equilibrium with its environment. However, it does not experience self-propulsion in such circumstances, except in higher order. Nevertheless, such a body may experience both a normal torque and a lateral force when adjacent to an ordinary surface with transverse translational symmetry. We explore how these phenomena arise, discuss what terminal velocities might be achieved, and point out some of the limitations of applying our results to observations, including the Lorenz-Lorentz correction, and the cooling due to radiation. In spite of these limitations, the effects discussed would seem to be observable.Comment: 20 pages, 8 figure

The association between social support and medication adherence in patients with hypertension: A systematic review

Background: Medication adherence is a primary determinant of treatment success in hypertensive patients. One of the challenges for healthcare providers that has received little attention is the impact of patients’ social supports on medication adherence. Objective: This review evaluates the impact of patients’ social supports on medication adherence in hypertensive patients. Methods: A systematic review methodology was used. Pubmed, CINAHL, Embase, and PsycINFO databases were searched systematically for relevant articles. The outcome measure in the studies was medication adherence in hypertension. Results: From 1155 articles, 238 were retained for further assessment, and finally, 14 met the inclusion criteria. Statistically significant positive associations between medication adherence and social support were found in nine studies (p<0.05). Conclusions: This review evaluated the impact of social support on medication adherence and highlighted gaps in the literature regarding the impact of social support on adherence. Family members or peer support may promote better adherence in some patient groups. This review suggests that healthcare providers may need to consider whether patients have appropriate social supports in place which will assist them adhering to and benefiting from treatment recommendations

Trajectories and stability of self-reported short sleep duration from adolescence to adulthood

The trajectories and stability of self-reported sleep duration recorded at ages 13, 15, and 23&nbsp;years on reported sleep duration at age 30&nbsp;years among 1105 students (55% male) who participated in the Norwegian Longitudinal Health and Behaviour Study were examined. Questionnaire data were used to obtain demographic and sleep variables. Dichotomised short sleep duration was based on normative values and set as &le;8.5&nbsp;h (age 13&nbsp;years), &le;8&nbsp;h (age 15&nbsp;years) and &le;7&nbsp;h (ages 23 and 30&nbsp;years). Results indicated a significant overall reduction in total sleep duration (h per night) across age groups. Sleep duration (continuous) at age 15 and 23&nbsp;years (whole group) was moderately but positively correlated with sleep duration at age 30&nbsp;years (P&nbsp;&lt;&nbsp;0.01). When split by sex, at age 15&nbsp;years, this association was present among females only (P&nbsp;&lt;&nbsp;0.01); however, at age 23&nbsp;years, this association was present in both male and females (both P&nbsp;&lt;&nbsp;0.001). Categorical short sleep at age 23&nbsp;years (whole group) was associated with short sleep at age 30&nbsp;years (unadjusted odds ratio&nbsp;=&nbsp;3.67, 95% confidence interval 2.36-5.69). Following sex stratification, this effect was significant for both males (unadjusted odds ratio&nbsp;=&nbsp;3.77, 95% confidence interval: 2.22-6.42) and females (unadjusted odds ratio&nbsp;=&nbsp;2.71, 95% confidence interval: 1.46-5.04). No associations were noted for categorical short sleep at ages 13 or 15&nbsp;years, and subsequent short sleep at 30&nbsp;years. Habitual short sleep duration during middle adulthood is not sustained from the time of early adolescence. Rather, these trends appear to be formed during early adulthood

Excessive daytime sleepiness and falls among older men and women: cross-sectional examination of a population-based sample

Background: Excessive daytime sleepiness (EDS) has been associated with an increased risk for falls among clinical samples of older adults. However, there is little detailed information among population-representative samples. The current study aimed to assess the relationship between EDS and falls among a cohort of population-based older adults. Methods: This study assessed 367 women aged 60-93years (median 72, interquartile range 65-79) and 451 men aged 60-92years (median 73, interquartile range 66-80) who participated in the Geelong Osteoporosis Study between the years 2001 and 2008. Falls during the prior year were documented via self-report, and for men, falls risk score was obtained using an Elderly Fall Screening Test (EFST). Sleepiness was assessed using the Epworth Sleepiness Scale (ESS), and scores of&ge;10 indicated EDS. Differences among those with and without EDS in regard to falls were tested using logistic regression models. Results: Among women, 50 (13.6 %) individuals reported EDS. Women with EDS were more likely to report a fall, and were more likely to report the fall occurring outside. EDS was similarly associated with an increased risk of a fall following adjustment for use of a walking aid, cases of nocturia and antidepressant medication use (adjusted OR&isin;=&isin;2.54, 95 % CI 1.24-5.21). Multivariate modelling revealed antidepressant use (current) as an effect modifier (p&isin;&lt;&isin;.001 for the interaction term). After stratifying the data by antidepressant medication use, the association between EDS and falls was sustained following adjustment for nocturia among antidepressant non-users (adjusted OR&isin;=&isin;2.63, 95 % CI 1.31-5.30). Among men, 72 (16.0 %) individuals reported EDS. No differences were detected for men with and without EDS in regard to reported falls, and a trend towards significance was noted between EDS and a high falls risk as assessed by the EFST (p&isin;=&isin;0.06), however, age explained this relationship (age adjusted OR&isin;=&isin;2.20, 95 % CI 1.03-1.10). Conclusions: For women, EDS is independently associated with at least one fall during the previous year, and this is more likely to occur whilst located outside. Amelioration of EDS may assist in improving functional outcomes among these individuals by reducing the risk for falls

An integrated multi-study analysis of intra-subject variability in cerebrospinal fluid amyloid-β concentrations collected by lumbar puncture and indwelling lumbar catheter

INTRODUCTION: Amyloid-β (Aβ) has been investigated as a diagnostic biomarker and therapeutic drug target. Recent studies found that cerebrospinal fluid (CSF) Aβ fluctuates over time, including as a diurnal pattern, and increases in absolute concentration with serial collection. It is currently unknown what effect differences in CSF collection methodology have on Aβ variability. In this study, we sought to determine the effect of different collection methodologies on the stability of CSF Aβ concentrations over time. METHODS: Grouped analysis of CSF Aβ levels from multiple industry and academic groups collected by either lumbar puncture (n=83) or indwelling lumbar catheter (n=178). Participants were either placebo or untreated subjects from clinical drug trials or observational studies. Participants had CSF collected by lumbar puncture or lumbar catheter for quantitation of Aβ concentration by enzyme linked immunosorbent assay. Data from all sponsors was converted to percent of the mean for Aβ40 and Aβ42 for comparison. Repeated measures analysis of variance was performed to assess for factors affecting the linear rise of Aβ concentrations over time. RESULTS: Analysis of studies collecting CSF via lumbar catheter revealed tremendous inter-subject variability of Aβ40 and Aβ42 as well as an Aβ diurnal pattern in all of the sponsors' studies. In contrast, Aβ concentrations from CSF samples collected at two time points by lumbar puncture showed no significant differences. Repeated measures analysis of variance found that only time and draw frequency were significantly associated with the slope of linear rise in Aβ40 and Aβ42 concentrations during the first 6 hours of collection. CONCLUSIONS: Based on our findings, we recommend minimizing the frequency of CSF draws in studies measuring Aβ levels and keeping the frequency standardized between experimental groups. The Aβ diurnal pattern was noted in all sponsors' studies and was not an artifact of study design. Averaging Aβ concentrations at each time point is recommended to minimize the effect of individual variability. Indwelling lumbar catheters are an invaluable research tool for following changes in CSF Aβ over 24-48 hours, but factors affecting Aβ concentration such as linear rise and diurnal variation need to be accounted for in planning study designs

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

Past as global trade governance prelude: reconfiguring debate about reform of the multilateral trading system

This paper peers backwards into the history of the multilateral trading system and its development over the past half century as a means of considering what may lie beyond the horizon for the future of global trade governance. Its purpose is to underscore the necessity and urgency for root-and-branch reform of the multilateral trading system. It achieves this by comparing and contrasting the global trading system of 50 years ago with its modern-day equivalent and its likely future counterpart half-a-century hence. In so doing, the paper throws into sharp relief not only the inadequacies of global trade governance today but also the damaging consequences of not fundamentally reforming the system in the near future, with a particular emphasis on the past, present and future development of the world’s poorest and most marginalised countries

The serotonin receptor 3E variant is a risk factor for female IBS-D

Irritable bowel syndrome (IBS) is a gut-brain disorder of multifactorial origin. Evidence of disturbed serotonergic function in IBS accumulated for the 5-HT3 receptor family. 5-HT3Rs are encoded by HTR3 genes and control GI function, and peristalsis and secretion, in particular. Moreover, 5-HT3R antagonists are beneficial in the treatment of diarrhea predominant IBS (IBS-D). We previously reported on functionally relevant SNPs in HTR3A c.-42C > T (rs1062613), HTR3C p.N163K (rs6766410), and HTR3E c.*76G > A (rs56109847 = rs62625044) being associated with IBS-D, and the HTR3B variant p.Y129S (rs1176744) was also described within the context of IBS. We performed a multi-center study to validate previous results and provide further evidence for the relevance of HTR3 genes in IBS pathogenesis. Therefore, genotype data of 2682 IBS patients and 9650 controls from 14 cohorts (Chile, Germany (2), Greece, Ireland, Spain, Sweden (2), the UK (3), and the USA (3)) were taken into account. Subsequent meta-analysis confirmed HTR3E c.*76G > A (rs56109847 = rs62625044) to be associated with female IBS-D (OR = 1.58; 95% CI (1.18, 2.12)). Complementary expression studies of four GI regions (jejunum, ileum, colon, sigmoid colon) of 66 IBS patients and 42 controls revealed only HTR3E to be robustly expressed. On top, HTR3E transcript levels were significantly reduced in the sigma of IBS patients (p = 0.0187); more specifically, in those diagnosed with IBS-D (p = 0.0145). In conclusion, meta-analysis confirmed rs56109847 = rs62625044 as a risk factor for female IBS-D. Expression analysis revealed reduced HTR3E levels in the sigmoid colon of IBS-D patients, which underlines the relevance of HTR3E in the pathogenesis of IBS-D