Finite Temperature Casimir Effect in the Presence of Extra Dimensions

We consider the finite temperature Casimir force acting on two parallel plates in a closed cylinder with the same cross section of arbitrary shape in the presence of extra dimensions. Dirichlet boundary conditions are imposed on one plate and fractional Neumann conditions with order between zero (Dirichlet) and one (Neumann) are imposed on the other plate. Formulas for the Casimir force show that it is always attractive for Dirichlet boundary conditions, and is always repulsive when the fractional order is larger than 1/2. For some fractional orders less than 1/2, the Casimir force can be either attractive or repulsive depending on the size of the internal manifold and temperature.Comment: To appear in the proceedings of 9th Conference on Quantum Field Theory under the Influence of External Conditions (QFEXT 09): Devoted to the Centenary of H. B. G. Casimir, Norman, Oklahoma, 21-25 Sep 200

Investigating the Bank-Lending Channel in South Africa: A VAR Approach

The monetary policy transmission mechanism can broadly be categorised into three separate channels: the interest rate channel, the credit channel and the other asset price channel. This paper seeks to examine the bank-lending channel of the credit channel of monetary policy in South Africa by making use of structural vector auto- regressions (SVAR’s). The pass-through effects of a change in the repurchase (repo) rate on bank deposits and loans and output, are tested using a parsimonious vector error correction model (PVECM). The Johansen (1988) cointegration procedure is used to test for a demand- or supply-driven bank-lending channel. In this way, the validity and effectiveness of the monetary policy regime in South Africa is tested and evaluated.monetary transmission mechanism, bank-lending channel, VAR, VECM, Johansen cointegration test

The Marginal Cost of Frailty Among Medicare Patients on Hemodialysis.

Introduction:Dialysis patients incur disproportionately high costs compared with other Medicare beneficiaries. Care for frail individuals may be even more costly. We examined the extent to which frailty contributes to higher costs among dialysis patients. Methods:We used ACTIVE/ADIPOSE (A Cohort to Investigate the Value of Exercise/Analyses Designed to Investigate the Paradox of Obesity and Survival in ESRD) enrollees (adult hemodialysis patients evaluated from June 2009 to August 2011) in a retrospective cohort analysis. Individuals using Medicare as the primary payer were included. Fried's frailty phenotype was evaluated at baseline, 12, and 24 months. Costs were derived from linkage with the US Renal Data System (USRDS) and Medicare claims data. We used generalized estimating equations (GEEs) incorporating time-updated frailty and costs to evaluate adjusted point estimates and the marginal cost associated with being frail. We also investigated if frail patients who died during the study incurred higher costs than those who survived. Results:Among 771 enrollees in ACTIVE/ADIPOSE, 425 met inclusion criteria. Mean age was 56 ± 13 years, body mass index (BMI) 29.2 ± 7.1 kg/m2, 42.4% were women, and 29.0% were frail at baseline. Over a mean follow-up of 2.3 years, frail individuals incurred 22% (95% confidence interval [CI] 9.6%-35.8%) higher costs compared with nonfrail individuals ($87,600 per patient per year [pppy], 95$71,800 pppy, 95% CI 64,800-79,600), the difference was driven primarily by higher inpatient expenditures. The difference between frail and nonfrail patients' inpatient expenditures was even more pronounced among those who died during the study compared with those who survived. Conclusions:Frail dialysis patients incur a significantly higher cost relative to their nonfrail counterparts, primarily driven by higher inpatient costs. Frail patients near end of life incur even higher costs

Incommensurate chirality density wave transition in a hybrid molecular framework

Using single-crystal X-ray diffraction we characterise the 235\,K incommensurate phase transition in the hybrid molecular framework tetraethylammonium silver(I) dicyanoargentate, [NEt$_4$]Ag$_3$(CN)$_4$. We demonstrate the transition to involve spontaneous resolution of chiral [NEt$_4$]$^+$ conformations, giving rise to a state in which molecular chirality is incommensurately modulated throughout the crystal lattice. We refer to this state as an incommensurate chirality density wave (XDW) phase, which represents a fundamentally new type of chiral symmetry breaking in the solid state. Drawing on parallels to the incommensurate ferroelectric transition of NaNO$_2$ we suggest the XDW state arises through coupling between acoustic (shear) and molecular rotoinversion modes. Such coupling is symmetry-forbidden at the Brillouin zone centre but symmetry-allowed for small but finite modulation vectors $\mathbf q=[0,0,q_z]^\ast$. The importance of long-wavelength chirality modulations in the physics of this hybrid framework may have implications for the generation of mesoscale chiral textures, as required for advanced photonic materials.Comment: 5 pages, 3 figure

Effect of a pedometer-based walking intervention on body composition in patients with ESRD: a randomized controlled trial.

BackgroundA randomized trial of a pedometer-based intervention with weekly activity goals led to a modest increase in step count among dialysis patients. In a secondary analysis, we investigated the effect of this intervention on body composition.MethodsSixty dialysis patients were randomized to standard care or a 6-month program consisting of 3 months of pedometers and weekly step count targets and 3 months of post-intervention follow-up. We obtained bioelectrical impedance spectroscopy (BIS) data on 54 of these patients (28 control, 26 intervention) and used linear mixed-modeling (adjusted for sex and dialysis modality) to estimate differences in change in total-body muscle mass (TBMM) adjusted for height2, fat mass (kg), and body mass index (BMI) (kg/m2) between control and intervention groups.ResultsThe median age of participants was 57.5 years (53-66), and 76% were men. At baseline, there was no significant difference between groups in age, BMI, race, or body composition, but there were more men in the intervention group. After 3 months, patients in the intervention group increased their average daily steps by 2414 (95% CI 1047, 3782) more than controls (p < 0.001), but there were no significant differences in body composition. However, at 6 months, participants in the intervention had a significantly greater increase from baseline in TBMM of 0.7 kg/m2 (95% CI 0.3, 1.13), decrease in fat mass (- 4.3 kg [95% CI -7.1, - 1.5]) and decrease in BMI (- 1.0 kg/m2 [95% CI -1.8, - 0.2]) relative to controls. In post-hoc analysis, each increase of 1000 steps from 0 to 3 months was associated with a 0.3 kg decrease in fat mass (95% CI 0.05, 0.5) from 0 to 6 months, but there was no dose-response relationship with TBMM/ht2 or BMI.ConclusionA pedometer-based intervention resulted in greater decreases in fat mass with relative preservation of muscle mass, leading to a greater decrease in BMI over time compared with patients not in the intervention. These differences were driven as much by worsening in the control group as by improvement in the intervention group. Step counts had a dose-response relationship with decrease in fat mass.Trial registrationClinicalTrials.gov (NCT02623348). 02 December 2015

Prevalence, incidence and etiology of hyponatremia in elderly patients with fragility fractures

Peer reviewedPublisher PD

Bose-Einstein condensation for interacting scalar fields in curved spacetime

We consider the model of self-interacting complex scalar fields with a rigid gauge invariance under an arbitrary gauge group $G$. In order to analyze the phenomenon of Bose-Einstein condensation finite temperature and the possibility of a finite background charge is included. Different approaches to derive the relevant high-temperature behaviour of the theory are presented.Comment: 28 pages, LaTe

Evaluating Creative Choice in K-12 Computer Science Curriculum

Computer Science is an increasingly important topic in K-12 education. Ever since the computing crisis of the early 2000s, where enrollment in CS dropped by over half in a five year span, increasing research has gone into improving and broadening enrollment in CS courses. Research shows the importance of introducing CS at a young age and the need for more exposure for younger children and young adults alike in order to work towards equity in the field. While there are many reasons for disinterest in CS courses, studies found one reason young adults do not want to study CS is a perception of it being tedious and lacking opportunities for creativity. Making more creative assignments is one way to try and engage more students who may not feel like stereotypical computer scientists. This thesis focuses in on the effects of creative choice in CS curriculum on students\u27 self-efficacy, engagement/preferences, and performance. It aims to capture the effects of creative choice on a range of K-12 students of varying demographics in order to make CS more accessible for everyone. The first half of the thesis experimentally validates the effects of creative choice in existing 5th grade CS classes. We created two variants of worksheets for the students - creative worksheets and rigid worksheets. After distributing these worksheets, surveys, and quizzes, we found students still feel a sense of ownership with limited versions of creative choice and benefit from a blend of creative and rigid instructions. In addition, student performance was not affected by our different treatments. The second half of the thesis adapted and launched the fifth grade curriculum to a new demographic, teaching the course to Juvenile Hall students. Student surveys and reports from their teacher showed this class had a positive impact and was well received by students and staff. We found students would prefer a longer class next iteration, as this one only extended five weeks. Future work will be needed to experimentally evaluate the specific impact of creative choice in this new demographic