Josephson tunneling of dark solitons in a double-well potential

We study the dynamics of matter waves in an effectively one-dimensional Bose-Einstein condensate in a double well potential. We consider in particular the case when one of the double wells confines excited states. Similarly to the known ground state oscillations, the states can tunnel between the wells experiencing the physics known for electrons in a Josephson junction, or be self-trapped. As the existence of dark solitons in a harmonic trap are continuations of such non-ground state excitations, one can view the Josephson-like oscillations as tunnelings of dark solitons. Numerical existence and stability analysis based on the full equation is performed, where it is shown that such tunneling can be stable. Through a numerical path following method, unstable tunneling is also obtained in different parameter regions. A coupled-mode system is derived and compared to the numerical observations. Regions of (in)stability of Josephson tunneling are discussed and highlighted. Finally, we outline an experimental scheme designed to explore such dark soliton dynamics in the laboratory.Comment: submitte

A Comparison of Quartz Crystal Microbalance Measurements with Mass Spectrometer Determinations

An experimental program was undertaken in which mass accretion rates, as determined by a liquid nitrogen cooled quartz crystal microbalance, were compared with the mass flux rates, as determined by both a cycloidal type and a quadrupole type residual gas analyzer for five simple materials. The data indicate a high degree of correlation between these instruments insofar as the shape of the curves. There are large variations however among the absolute values

Opmerkings oor Sotho-Morfologie

Noord-Sotho, ook genaamd Sepedi, is ’n dialek van die Noord-Transvaalse Sothogroep van Bantoetale. In vroeër jare is dit veral deur sendelinge verhef tot skryftaal. Vanaf 1930 eers is tekens van letterkundige genres op te merk. Intussen het daar ook ’n paar grammatikaboekies versky.n, waarvan dié van Endemann die mees wetenskaplike is. Studies oor fonetiek, fonologie en morfologie en sintaksis ontbreek

Geothermal reservoir engineering research

The Stanford University research program on the study of stimulation and reservoir engineering of geothermal resources commenced as an interdisciplinary program in September, 1972. The broad objectives of this program have been: (1) the development of experimental and computational data to evaluate the optimum performance of fracture-stimulated geothermal reservoirs; (2) the development of a geothermal reservoir model to evaluate important thermophysical, hydrodynamic, and chemical parameters based on fluid-energy-volume balances as part of standard reservoir engineering practice; and (3) the construction of a laboratory model of an explosion-produced chimney to obtain experimental data on the processes of in-place boiling, moving flash fronts, and two-phase flow in porous and fractured hydrothermal reservoirs

Sexual Offences Courts: Better justice for children?

Child victims of sexual abuse are vulnerable witnesses who experience trauma and secondary victimisation when they testify in sexual abuse cases. Sexual Offences Courts aim to alleviate this problem in various ways. The main focus of this article is to examine the prescribed blueprint for Sexual Offences Courts in order to determine whether blueprint-compliant Sexual Offences Courts contribute to better justice for child victims of sexual offences. Each blueprint requirement is therefore analysed with the aim of determining whether possible advantages for child victims can be identified.The conclusion is reached that substantial advantages for child victims are provided by blueprint compliant Sexual Offences Courts. By 2005 54 Sexual Offences Courts were established countrywide and official statistics indicate that these courts are very successful. However, despite numerous commitments by government to establish more of these courts, a moratorium on the establishment of new courts was announced. It is argued that blueprint compliant Sexual Offences Courts do indeed provide better justice for children and therefore more of these courts should be established at a much faster rate

Decomposition of NO studied by infrared emission and CO laser absorption

A diagnostic technique for monitoring the concentration of NO using absorption of CO laser radiation was developed and applied in a study of the decomposition kinetics of NO. Simultaneous measurements of infrared emission by NO at 5.3 microns were also made to validate the laser absorption technique. The data were obtained behind incident shocks in NO-N2O-Ar (or Kr) mixtures, with temperatures in the range 2400-4100 K. Rate constants for dominant reactions were inferred from comparisons with computer simulations of the reactive flow

Sexual Offences Courts in South Africa: Quo vadis?

Since the establishment of the first Sexual Offences Court in Wynberg in 1993, various developments have taken place that include, but are not limited to, the following: several investigations into these courts were undertaken; the Sexual Offences and Community Affairs Unit (SOCA Unit) was established; a blueprint for Sexual Offences Courts was drafted and later refined; and, by 2007, the number of Sexual Offences Courts had increased to 59. These courts have performed exceptionally well compared with general regional courts and conviction rates rose to 70 per cent on average. Despite the obvious success of these courts, the Minister of Justice and Constitutional Development declared a moratorium on the establishment of additional Sexual Offences Courts pending the outcome of an evaluation of existing Sexual Offences Courts. In this article, a synopsis of the development of Sexual Offences Courts is given and the subsequent evaluation commissioned by the Minister is assessed and is supplemented with recommendations to enhance efforts to combat sexual offences through the Sexual Offences Courts

Impact of urbanisation on Serum lipid profiles -the thusa survey

Objective. To examine the impact of urbanisation on lipid profiles of black South Africans, stratified for HIV status.Design. Cross-sectional population-based survey.Setting. North West province of South Africa.Subjects. A representative sample of 1854 apparently healthy volunteers aged ≥ 15 years, was recruited from 37 randomly selected sites throughout the province. Subjects were stratified into five urbanisation strata (S): Sl rural villages, S2 farms, S3 informal housing or 'squatter camps', S4 urban townships, and S5 surburban housing.Outcome measures. Demographic, physical activity and dietary intake information was collected using validated and culture-sensitive questionnaires. Anthropometric measurements and lipid analyses were determined using standardised methodology.Results. The results revealed significantly lower mean(95% confidence interval) total serum cholesterol (TC) levels in HIV-negative men in Sl -S4 compared with S5 (S1 3.91 (3.77- 4.05) v. S5 4.79 (4.54- 5.04) mmol/1). In HIV-negative women, TC levels were significantly lower in Sl - S3 than in S4 and S5 (S1 4.05 (3.94- 4.17) v. S5 4.79 (4.59- 5.00) mmol/1). The same trends were seen for serum low-density lipoprotein cholesterol (LDLC) and triglycerides and in HIV-positive subjects. Binary logistical analysis indicated that the main factor responsible for the increased TC levels seemed to be increased body mass index (BMI) due to decreased physical activity. Conclusions. Serum lipid levels increased with urbanisation although they remained within levels recommended for ther populations. This may, however, become an important health problem in future if preventive strategies are not implemented. Culturally sensitive physical activity programmes to decrease BMI, targeted at professional me and women, and women in urban townships, seem to constitute the most appropriate intervention

The Radius of Metric Subregularity

There is a basic paradigm, called here the radius of well-posedness, which quantifies the "distance" from a given well-posed problem to the set of ill-posed problems of the same kind. In variational analysis, well-posedness is often understood as a regularity property, which is usually employed to measure the effect of perturbations and approximations of a problem on its solutions. In this paper we focus on evaluating the radius of the property of metric subregularity which, in contrast to its siblings, metric regularity, strong regularity and strong subregularity, exhibits a more complicated behavior under various perturbations. We consider three kinds of perturbations: by Lipschitz continuous functions, by semismooth functions, and by smooth functions, obtaining different expressions/bounds for the radius of subregularity, which involve generalized derivatives of set-valued mappings. We also obtain different expressions when using either Frobenius or Euclidean norm to measure the radius. As an application, we evaluate the radius of subregularity of a general constraint system. Examples illustrate the theoretical findings.Comment: 20 page