Testing the interaction of dark energy to dark matter through the analysis of virial relaxation of clusters Abell Clusters A586 and A1689 using realistic density profiles

Interaction between dark energy and dark matter is probed through deviation from the virial equilibrium for two relaxed clusters: A586 and A1689. The evaluation of the virial equilibrium is performed using realistic density profiles. The virial ratios found for the more realistic density profiles are consistent with the absence of interaction.Comment: 16pp 1 fig; accepted by GeR

Electronic damping of molecular motion at metal surfaces

A method for the calculation of the damping rate due to electron-hole pair excitation for atomic and molecular motion at metal surfaces is presented. The theoretical basis is provided by Time Dependent Density Functional Theory (TDDFT) in the quasi-static limit and calculations are performed within a standard plane-wave, pseudopotential framework. The artificial periodicity introduced by using a super-cell geometry is removed to derive results for the motion of an isolated atom or molecule, rather than for the coherent motion of an ordered over-layer. The algorithm is implemented in parallel, distributed across both ${\bf k}$ and ${\bf g}$ space, and in a form compatible with the CASTEP code. Test results for the damping of the motion of hydrogen atoms above the Cu(111) surface are presented.Comment: 10 pages, 3 figure

Pattern fluctuations in transitional plane Couette flow

In wide enough systems, plane Couette flow, the flow established between two parallel plates translating in opposite directions, displays alternatively turbulent and laminar oblique bands in a given range of Reynolds numbers R. We show that in periodic domains that contain a few bands, for given values of R and size, the orientation and the wavelength of this pattern can fluctuate in time. A procedure is defined to detect well-oriented episodes and to determine the statistics of their lifetimes. The latter turn out to be distributed according to exponentially decreasing laws. This statistics is interpreted in terms of an activated process described by a Langevin equation whose deterministic part is a standard Landau model for two interacting complex amplitudes whereas the noise arises from the turbulent background.Comment: 13 pages, 11 figures. Accepted for publication in Journal of statistical physic

Convexity in partial cubes: the hull number

We prove that the combinatorial optimization problem of determining the hull number of a partial cube is NP-complete. This makes partial cubes the minimal graph class for which NP-completeness of this problem is known and improves some earlier results in the literature. On the other hand we provide a polynomial-time algorithm to determine the hull number of planar partial cube quadrangulations. Instances of the hull number problem for partial cubes described include poset dimension and hitting sets for interiors of curves in the plane. To obtain the above results, we investigate convexity in partial cubes and characterize these graphs in terms of their lattice of convex subgraphs, improving a theorem of Handa. Furthermore we provide a topological representation theorem for planar partial cubes, generalizing a result of Fukuda and Handa about rank three oriented matroids.Comment: 19 pages, 4 figure

Prevention of restenosis after coronary balloon angioplasty: rationale and design of the Fluvavastatin Angioplasty Restenosis (FLARE) Trial

Prevention of restenosis after successful percutaneous transluminal coronary balloon angioplasty (PTCA) continues to present the greatest therapeutic challenge in interventional cardiology. Experimental and pathological studies describe restenosis as no more than the biologic healing response to arterial injury. Studies of serial quantitative coronary angiography have demonstrated that this biologic process may be measured as the loss in minimal luminal diameter (MLD) from post-PTCA to follow-up angiography and that it is essentially ubiquitous and normally distributed. Thus, quantitative coronary angiography has become the gold standard for evaluation of the angiographic outcome of clinical trials of new agents and devices aimed at prevention of restenosis. The 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors inhibit biosynthesis of mevalonate, a precursor of non-sterol compounds involved in cell proliferation, and thus may control the neointimal response, which forms the kernel of restenosis. Experimental evidence suggests that fluvastatin may exert a greater direct inhibitory effect on proliferating vascular myocytes than other HMG-CoA reductase inhibitors, independent of any lipid-lowering action. The Fluvastatin Angioplasty Restenosis (FLARE) Trial was conceived, in collaboration between the Thoraxcenter, Erasmus University, Rotterdam, The Netherlands, and Sandoz Pharma, to evaluate the ability of fluvastatin 40 mg twice daily to reduce restenosis after successful single-lesion PTCA. Treatment of suitable patients begins 2 weeks before PTCA and continues after successful PTCA (residual diameter stenosis < 50%, without major cardiac complications) to follow-up angiography at 26 +/- 2 weeks. Restenosis is measured by quantitative coronary angiography at a core laboratory as the loss in MLD from post-PTCA to follow-up angiography. It is calculated (90% power, alpha = 0.05) that 730 evaluable patients will be needed to tes

A description of patients with recurrence of pulmonary tuberculosis in TB hospital, Ermelo

Thesis (MMed)--Stellenbosch University, 2015.South Africa is one of the high burden countries for TB in Sub Sahara in Africa with Mpumalanga as one of the provinces with a high burden of disease. Data available on tuberculosis in Msukaligwa indicate the following: Cure Rate 40%; Smear conversion at the end of intensive phase 35% and Defaulter Rate 27.5%. The problem of TB is made worse by the twin epidemic of HIV, with a prevalence of 38.9% in our district -the highest among the 3 districts in the province. Retreatment TB carries the risk of developing TB drug resistance with severe consequences for the patient and the population. Understanding the characteristics of these patients will help in designing interventions to prevent the problem, promote a high cure rate for patients with TB in our health care system and reduce to minimum the burden of re-treatment pulmonary TB on our health care facilities and community. One critical precondition for Retreatment TB is non adherence to TB treatment. Factors responsible for non adherence could be classified as individual patient factors; Co-morbid conditions; Health system; treatment related and Community factors. The outcomes of Retreatment TB could be, cure, and death and failure of treatment leading to drug resistance. The Setting of this study is the 58-bedded TB hospital in Ermelo. The Aim of the study was to describe the occurrence, characteristics and management outcome of Retreatment Pulmonary Tuberculosis in patients in the Ermelo TB hospital. The specific Objectives were to describe the socio-demographic, behavioural and clinical factors related to recurrence of the TB in patients; to determine the contribution of non adherence to treatment on recurrence of TB in the study population; to identify the prevalence of resistance to TB medication among patients with Retreatment TB ; to identify treatment outcomes in patients who have been followed up for the duration of Retreatment TB and finally to make recommendations to the Department of Health, Mpumalanga towards minimizing Retreatment TB and improving the overall TB programme. The Study design is cross sectional and descriptive; the study population comprised of patients admitted with TB at Ermelo TB hospital aged 15 years and older between 1 January 2005 and 31 December 2007.No specific probability sampling was applied in the selection of the patients. Data Collection involved visits to the TB hospital during the period and extracting the relevant information from the patient medical records and the TB register using a predesigned data collection form. Data analysis was done by the statistician from the Centre for Statistical Consultation, University of Stellenbosch. Being a descriptive study, the data analysis expresses the prevalence of various factors associated with retreatment TB. This study met the Ethical approval of the University of Stellenbosch as well as the Research Ethics Committee of the Department of Health & Social Services, Mpumalanga. Findings All the three hundred and eighty eight patient records with retreatment TB forming 19.6% of TB patients admitted between 2005 and 2007 were reviewed. The distributions of the patients were: males 66%; mean age of 41.4 years; females 34%; mean age 35.3 years. They were mostly unemployed; primary education 93%; unmarried 43% and married 34%.Retreatment TB was diagnosed with sputum smear microscopy in 71% with bacilli load of 3+ in 45%.The sources of referral to TB hospital were: public hospital 71 %; private doctors 2%. 74% of the patients have had TB 1-3 years before the episode under study. Retreatment TB categories were: after treatment completed 69%; default 19%; after cure 8% and treatment failure 4%. 98% of patients tested had +ve HIV status; the median CD4 cell count was 106 cells/µl at the time of retreatment; very few (5%) were on ART. Drug resistance to primary TB drugs was as follows: Rifampicin 16%; Isoniazid 29%; Ethambutol 19% and Streptomycin 23%. The treatment outcomes for those whom data were available were: successful 49.1%, death 23.8%; treatment default 22.9%. MDR-TB complicated 3.3% of the patients. Conclusion: Majority of the retreatment TB patients were males with an average age of 41years and unemployed. More than two thirds of the patient had completed TB treatment previously and default on treatment accounted for less than one quarter of retreatment categories. The process of care was better in terms of diagnosis of TB with sputum smear. Improvement in the documentation of key factors like smoking, alcohol, drug use among patients and co-morbidity as well as counselling and testing for HIV and provision of ARTs is required. Treatment outcomes with regards to successful outcome need to be monitored and improved upon.AFRIKAANSE OPSOMMING: Geen opsomming beskikbaa

Macromolecular Traits in the African Rice Oryza glaberrima and in Glaberrima/Sativa Crosses, and Their Relevance to Processing

Molecular properties of proteins and starch were investigated in 2 accessions of Oryza glaberrima and Oryza sativa, and in one NERICA cross between the 2 species, to assess traits that could be relevant to transformation into specific foods. Protein nature and organization in O. glaberrima were different from those in O. sativa and in NERICA. Despite the similar cysteine content in all samples, thiol accessibility in O. glaberrima proteins was higher than in NERICA or in O. sativa. Inter-protein disulphide bonds were important for the formation of protein aggregates in O. glaberrima, whereas non-covalent protein-protein interactions were relevant in NERICA and O. sativa. DSC and NMR studies indicated only minor differences in the structure of starch in these species, as also made evident by their microstructural features. Nevertheless, starch gelatinization in O. glaberrima was very different from what was observed in O. sativa and NERICA. The content of soluble species in gelatinized starch from the various species in the presence/absence of treatments with specific enzymes indicated that release of small starch breakdown products was lowest in O. glaberrima, in particular from the amylopectin component. These findings may explain the low glycemic index of O. glaberrima, and provide a rationale for extending the use of O. glaberrima in the production of specific rice-based products, thus improving the economic value and the market appeal of African crops

Quantum properties of transverse pattern formation in second-harmonic generation

We investigate the spatial quantum noise properties of the one dimensional transverse pattern formation instability in intra-cavity second-harmonic generation. The Q representation of a quasi-probability distribution is implemented in terms of nonlinear stochastic Langevin equations. We study these equations through extensive numerical simulations and analytically in the linearized limit. Our study, made below and above the threshold of pattern formation, is guided by a microscopic scheme of photon interaction underlying pattern formation in second-harmonic generation. Close to the threshold for pattern formation, beams with opposite direction of the off-axis critical wave numbers are shown to be highly correlated. This is observed for the fundamental field, for the second harmonic field and also for the cross-correlation between the two fields. Nonlinear correlations involving the homogeneous transverse wave number, which are not identified in a linearized analysis, are also described. The intensity differences between opposite points of the far fields are shown to exhibit sub-Poissonian statistics, revealing the quantum nature of the correlations. We observe twin beam correlations in both the fundamental and second-harmonic fields, and also nonclassical correlations between them.Comment: 18 pages, 17 figures, submitted to Phys. Rev.

Using Topological Statistics to Detect Determinism in Time Series

Statistical differentiability of the measure along the reconstructed trajectory is a good candidate to quantify determinism in time series. The procedure is based upon a formula that explicitly shows the sensitivity of the measure to stochasticity. Numerical results for partially surrogated time series and series derived from several stochastic models, illustrate the usefulness of the method proposed here. The method is shown to work also for high--dimensional systems and experimental time seriesComment: 23 RevTeX pages, 14 eps figures. To appear in Physical Review

Functional analyses of the RsmY and RsmZ small noncoding regulatory RNAs in Pseudomonas aeruginosa

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen with distinct acute and chronic virulence phenotypes. Whereas acute virulence is typically associated with expression of a type III secretion system (T3SS), chronic virulence is characterized by biofilm formation. Many of the phenotypes associated with acute and chronic virulence are inversely regulated by RsmA and RsmF. RsmA and RsmF are both members of the CsrA family of RNA-binding proteins and regulate protein synthesis at the posttranscriptional level. RsmA activity is controlled by two small noncoding regulatory RNAs (RsmY and RsmZ). Bioinformatic analyses suggest that RsmY and RsmZ each have 3 or 4 putative RsmA binding sites. Each predicted binding site contains a GGA sequence presented in the loop portion of a stem-loop structure. RsmY and RsmZ regulate RsmA, and possibly RsmF, by sequestering these proteins from target mRNAs. In this study, we used selective 2'-hydroxyl acylation analyzed by primer extension and mutational profiling (SHAPE-MaP) chemistry to determine the secondary structures of RsmY and RsmZ and functional assays to characterize the contribution of each GGA site to RsmY/RsmZ activity. Our data indicate that RsmA has two preferential binding sites on RsmY and RsmZ, while RsmF has one preferential binding site on RsmY and two sites on RsmZ. Despite RsmF and RsmA sharing a common consensus site, RsmF binding properties are more restrictive than those of RsmA