Casimir Energy for a Wedge with Three Surfaces and for a Pyramidal Cavity

Casimir energy calculations for the conformally coupled massless scalar field for a wedge defined by three intersecting planes and for a pyramid with four triangular surfaces are presented. The group generated by reflections are employed in the formulation of the required Green functions and the wave functions.Comment: Latex, 9 page

Boundary conditions and stability of a perfectly matched layer for the elastic wave equation in first order form

The article of record as published by be found at http://dx.doi.org/10.1016/j.jcp.2015.09.048In computations, it is now common to surround artificial boundaries of a computational domain with a perfectly matched layer (PML) of finite thickness in order to prevent artificially reflected waves from contaminating a numerical simulation. Unfortunately, the PML does not give us an indication about appropriate boundary conditions needed to close the edges of the PML, or how those boundary conditions should be enforced in a numerical setting. Terminating the PML with an inappropriate boundary condition or an unstable numerical boundary procedure can lead to exponential growth in the PML which will eventually destroy the accuracy of a numerical simulation everywhere. In this paper, we analyze the stability and the well-posedness of boundary conditions terminating the PML for the elastic wave equation in first order form. First, we consider a vertical modal PML truncating a two space dimensional computational domain in the horizontal direction. We freeze all coefficients and consider a left half-plane problem with linear boundary conditions terminating the PML. The normal mode analysis is used to study the stability and well-posedness of the resulting initial boundary value problem (IBVP). The result is that any linear well-posed boundary condition yielding an energy estimate for the elastic wave equation, without the PML, will also lead to a well-posed IBVP for the PML. Second, we extend the analysis to the PML corner region where both a horizontal and vertical PML are simultaneously active. The challenge lies in constructing accurate and stable numerical approximations for the PML and the boundary conditions. Third, we develop a high order accurate finite difference approximation of the PML subject to the boundary conditions. To enable accurate and stable numerical boundary treatments for the PML we construct continuous energy estimates in the Laplace space for a one space dimensional problem and two space dimensional PML corner problem. We use summation-by-parts finite difference operators to approximate the spatial derivatives and impose boundary conditions weakly using penalties. In order to ensure numerical stability of the discrete PML, it is necessary to extend the numerical boundary procedure to the auxiliary differential equations. This is crucial for deriving discrete energy estimates analogous to the continuous energy estimates. Numerical experiments are presented corroborating the theoretical results. Moreover, in order to ensure longtime numerical stability, the boundary condition closing the PML, or its corresponding discrete implementation, must be dissipative. Furthermore, the numerical experiments demonstrate the stable and robust treatment of PML corners

Effects of Cooperative Learning and Contingency Contracting on Attention Deficit Hyperactivity Disorder Among Pupils With Learning Disabilities in Mathematics in Owerri, Nigeria

The study adopted pretest-posttest, control group quasi-experimental design with a 3x2x2 factorial matrix. Multi-stage sampling technique was used to select ninety participants from three randomly selected public primary schools in the three local governments in Owerri. The participants were randomly assigned to treatments and control groups. Participants in the two treatment groups were exposed to eight weeks of cooperative learning strategy and contingency contracting technique. Two instruments used were: Vanderbilt ADHD Diagnostic Teacher Rating Scale (α= 0.93) and Woodcock-Johnson III Mathematics Fluency Achievement Tests Scale (α= 0.84). Two hypotheses were tested at 0.05 level of significance. Data were analysed using Analysis of Covariance. There is a significant main effect of treatment on ADHD pupils with learning disabilities in mathematics (F (2, 78) = 127.29, p<0.05). Cooperative learning strategy was more effective in improving Mathematics competence skills ( = 96.6) of ADHD pupils with learning disabilities in mathematics than contingency contracting technique. Furthermore, there is no significant interaction effect of treatment, age and gender on ADHD pupils with learning disabilities in mathematics in the study. Therefore, the findings of the study suggest that teachers should endevour to use appropriate teaching methods, cooperative learning strategy and contingency contracting technique to reinforce positive attitude to teaching-learning situations among ADHD pupils with learning disabilities in mathematics.

The liberal welfare state and the politics of pension reform : a comparative analysis of Canada and the United Kingdom

The provision of state pensions in the advanced countries faces two significant and reinforcing challenges. Demographic change and global economic pressure impact the provision of public pensions by increasing social spending and depending on the method of financing, the base of government’s revenues from which these programmes are funded. Countries belonging to the liberal welfare model, such as the UK and Canada, hold a common view on the primacy of the market and actively adapt measures that keep social benefits modest. Yet the reforms adopted by the UK and Canadian government reveal divergence. This presents a puzzle as the welfare state literature predicts convergence. Canada with its small domestic market and open economy has greater exposure to risks of globalisation than the UK, but it is the UK and not Canada that adopted the more radical reforms. To explain this puzzle, this thesis examines four cases: two different pensions’ schemes in each of the two countries – Canada and the UK. The thesis argues that the concentration of political authority is central to explaining the variation, although not the sole factor.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

A Tenon's capsule/bulbar conjunctiva interface biomimetic to model fibrosis and local drug delivery

Glaucoma filtration surgery is one of the most effective methods for lowering intraocular pressure in glaucoma. The surgery efficiently reduces intra-ocular pressure but the most common cause of failure is scarring at the incision site. This occurs in the conjunctiva/Tenon's capsule layer overlying the scleral coat of the eye. Currently used antimetabolite treatments to prevent post-surgical scarring are non-selective and are associated with potentially blinding side effects. Developing new treatments to target scarring requires both a better understanding of wound healing and scarring in the conjunctiva, and new means of delivering anti-scarring drugs locally and sustainably. By combining plastic compression of collagen gels with a soft collagen-based layer, we have developed a physiologically relevant model of the sub-epithelial bulbar conjunctiva/Tenon's capsule interface, which allows a more holistic approach to the understanding of subconjunctival tissue behaviour and local drug delivery. The biomimetic tissue hosts both primary human conjunctival fibroblasts and an immune component in the form of macrophages, morphologically and structurally mimicking the mechanical proprieties and contraction kinetics of ex vivo porcine conjunctiva. We show that our model is suitable for the screening of drugs targeting scarring and/or inflammation, and amenable to the study of local drug delivery devices that can be inserted in between the two layers of the biomimetic. We propose that this multicellular-bilayer engineered tissue will be useful to study complex biological aspects of scarring and fibrosis, including the role of inflammation, with potentially significant implications for the management of scarring following glaucoma filtration surgery and other anterior ocular segment scarring conditions. Crucially, it uniquely allows the evaluation of new means of local drug delivery within a physiologically relevant tissue mimetic, mimicking intraoperative drug delivery in vivo

Antioxidant and antimicrobial activities of Morchella conica Pers.

Antioxidant capacity and antimicrobial activities of Morchella conica Pers. extracts obtained with ethanol were investigated in this study. Four complementary test systems; namely DPPH free radical scavenging, -carotene/linoleic acid systems, total phenolic compounds and total flavonoid concentration were used. Inhibition values of M. conica ethanol extracts, buthylated hydroxyanisol (BHA) and -tocopherol standards were found to be 96.9, 98.9 and 99.2%, respectively, at aconcentration of 160 ìg/ml. When compared the inhibition levels of methanol extract of M. conica and standards in linoleic acid system, it was observed that the higher the concentration of both M. conicaethanol extract and the standards the higher the inhibition effect. Total flavonoid amount was 9.17±0.56ìg mg-1 quercetin equivalent while the phenolic compound amount was 41.93±0.29 ìg mg-1 pyrocatecholequivalent in the ethanolic extract. The antimicrobial effect of M. conica ethanol extract was tested against six species of Gram-positive bacteria, seven species of Gram-negative bacteria and one speciesof yeast. The M. conica ethanol extract had a narrow antibacterial spectrum against tested microorganisms. The most susceptible bacterium was M. flavus. The crude extract was found active on S. aureus ATCC 25923 and S. aureus Cowan I. The M. conica ethanol extract did not exhibit anticandidal activity against C. albican

Avascular necrosis in sickle cell (homozygous S) patients: Predictive clinical and laboratory indices

Background: Pathogenetic mechanism as well as laboratory and clinical correlates of osteonecrosis in sickle cell have not been fully investigated. The aim of this study is to investigate the predictive value of the steady state white cell and platelet count as well as the frequency of bone pain crisis per annum to detect sickle cell patients who will eventually develop avascular necrosis (AVN).Patients and Methods: A 5 year retrospective analysis of 122 homozygous S (HbSS) patients, aged 6‑49 years (mean age 24.7 ± 7 years), out of which 16 patients (13.1%) had developed AVN within the years under review.Results: The prevalence of AVN in sickle cell patients was determined to be 13.1 per 1000. The steady state white cell count, platelet count, frequency of bone pain crisis and hematocrit, was compared in patients that develop AVN and those who had not over the period. Only the steady state platelet count was found to differ significantly (P = 0.011) between these two patient groups and to correlate positively (Pearson correlation coefficient = −0.251) with development of AVN. The hematocrit, white cell count, and frequency of bone pain crisis were found neither to differ significantly nor correlate with the development of AVN.Conclusion: In conclusion, patients with a raised steady state platelet count may have a higher tendency to develop AVN and may require closer orthopedic review and prophylactic intervention.Key words: Avascular necrosis, homozygous S, platelet count, sickle cell anemia, white cell coun

Free-radical scavenging capacity and antimicrobial activity of wild edible mushroom from Turkey

Antioxidant capacity and antimicrobial activities of Ramaria flava (Schaeff) Quel. (RF) extracts obtained with ethanol were investigated in this study. Four complementary test systems; namely DPPH freeradical scavenging, -carotene/linoleic acid systems, total phenolic compounds and total flavonoid concentration have been used. Inhibition values of R. flava extracts, BHA and -tocopherol standardswere found to be 94.7, 98.9 and 99.2%, respectively, at 160&fnof;&Ecirc;g/ml. When compared the inhibition levels of ethanol extract of R. flava and standards in linoleic acid system, it was observed that the higher theconcentration of both RF ethanol extract and the standards the higher the inhibition effect. Total flavonoid amount was 8.27}0.28 &fnof;&Ecirc;g mg-1 quercetin equivalent while the total phenolic compound amountwas 39.83}0.32 &fnof;&Ecirc;g mg-1 pyrocatechol equivalent in the ethanolic extract. The ethanol extract of R. flava inhibited the growth of Gram-positive bacteria better than Gram-negative bacteria and yeast. The crude extract showed no antibacterial activity against Pseudomonas aeruginosa, Escherichia coli, Morganella morganii and Proteus vulgaris. The antimicrobial activity profile of R. flava against tested strains indicated that Micrococcus flavus, Micrococcus luteus and Yersinia enterocolitica was the most susceptible bacteria of all the test strains. R. flava was found to be inactive against Candida albicans

Vacuum-Induced Surface Freezing for the Freeze-Drying of the Human Growth Hormone: How Does Nucleation Control Affect Protein Stability?

Abstract In the present work, the effect of controlled nucleation on the stability of human growth hormone (hGH) during freeze-drying has been investigated. More specifically, the vacuum-induced surface freezing technique has been compared to conventional freezing, both with and without an annealing step. Size exclusion chromatography and cell-based potency assays have been used to characterize the formation of soluble aggregates and the biological activity of hGH, respectively. The results obtained indicate that controlled nucleation has a positive effect on both cycle performance and product homogeneity because of the formation of bigger ice crystals, and characterized by a narrower dimensional distribution. From the point of view of hGH stability, we observed that vacuum-induced surface freezing is not detrimental to the biological activity of the protein, or aggregate formation. In addition, the effect of 2 different formulations, including trehalose or cellobiose, on protein preservation was also considered for this study