Food insecurity among students at the University of the Free State, South Africa

Objective: The objective of this study was to investigate food insecurity in students in a developing country with high national food insecurity.Design: This was a cross-sectional survey.Subjects and setting: Registered students at the University of the Free State were invited to participate. Thirty-one thousand and fourteen students were enrolled in 2013. One thousand, four hundred and sixteen students completed a self-administered web-based questionnaire.Outcome measures: Food insecurity was assessed using a one-item measure, i.e. the Australian National Nutrition Survey, and a 10-item measure, i.e. the United States Department of Agriculture Community Food Security Assessment Toolkit. Associations of food insecurity with biographical attributes, food procurement measures and coping strategies were determined using the chi-square test and multivariate logistic regression analysis.Results: The prevalence of food insecurity according to the one-item measure was 65%. Using the 10-item measure, 60% of the students experienced food insecurity “with hunger”, and 26% food insecurity “without hunger”. The highest prevalence of food insecurity was in black and coloured, undergraduate, first-generation and male students, as well as in students who were unmarried, unemployed and those relying on loans or bursaries. Using the regression model, the strongest significant predictors of food insecurity were race, gender, being a first-generation student, not having enough food money, having borrowed food money from parents, having asked for food and having sold belongings to obtain food.Conclusion: Severe food insecurity in students may be contributing to the high attrition rates experienced by universities in South Africa. Urgent intervention is required, as not having access to enough nutritionally adequate and safe food could be one of the reasons why more than 50% of South African university students never graduate.Keywords: food insecurity, students, University of the Free State, South Afric

Characterizing CDMA downlink feasibility via effective interference

This paper models and analyses downlink power assignment feasibility in Code Division Multiple Access (CDMA) mobile networks. By discretizing the area into small segments, the power requirements are characterized via a matrix representation that separates user and system characteristics. We obtain a closed-form analytical expression of the so-called Perron-Frobenius eigenvalue of that matrix, which provides a quick assessment of the feasibility of the power assignment for each distribution of calls over the segments. Although the obtained relation is non-linear, it basically provides an effective interference characterisation of downlink feasibility. Our results allow for a fast evaluation of outage and blocking probabilities, and enable a quick evaluation of feasibility that may be used for Call Acceptance Control. \u

Pest-predator spatial relationships in winter rape: implications for integrated crop management

Douglas Warner, Les J Allen-Williams, Andrew W Ferguson, and Ingrid H Williams, 'Pest–predator spatial relationships in winter rape: implications for integrated crop management', Pest Management Science, Vol. 56 (11): 977-982, November 2000, doi: 10.1002/1526-4998(200011)56:113.0.CO;2-U. Copyright © 2000 Society of Chemical IndustryThe brassica pod midge (Dasineura brassicae) is an important and widespread pest of winter and spring oilseed rape throughout Europe. Pods infested by D brassicae larvae split prematurely, releasing seeds, and the larvae drop to the soil into which they burrow to pupate. At this stage in its lifecycle D brassicae is potentially vulnerable to predation by carabid beetles foraging on the soil surface. This is the first study in the UK to focus on carabid beetles as predators of D brassicae in the oilseed rape crop. The spatio-temporal distributions of larvae of D brassicae dropping to the soil from the crop canopy and of adult carabid beetles active on the soil surface were analysed in two consecutive years. Insect samples were collected from spatially referenced sampling points across each crop. Counts of insects were mapped and analysed, and the degree of spatial association between predator and prey determined using Spatial Analysis by Distance Indices (SADIE). Carabid species abundant and active during peak drop of first generation D brassicae larvae included Agonum dorsale, Amara similata, Harpalus rufipes and Nebria brevicollis. The larvae of D brassicae had a marked edge distribution within the crop. SADIE analysis revealed significant spatial association between larvae of D brassicae and adult H rufipes (P <0.05) in 1998, but not with adults of A dorsale, A similata or N brevicollis. In 1999, there was strong spatial association only between larvae of D brassicae and adult A dorsale (P <0.01). Aggregation of N brevicollis adults occurred in some areas of greatest D brassicae larval counts in 1999, but overall spatial association was not signi®cant. The distributions are discussed in terms of their relevance to integrated crop management (ICM) strategies and spatial targeting of insecticides.Peer reviewe

Large deviations for ideal quantum systems

We consider a general d-dimensional quantum system of non-interacting particles, with suitable statistics, in a very large (formally infinite) container. We prove that, in equilibrium, the fluctuations in the density of particles in a subdomain of the container are described by a large deviation function related to the pressure of the system. That is, untypical densities occur with a probability exponentially small in the volume of the subdomain, with the coefficient in the exponent given by the appropriate thermodynamic potential. Furthermore, small fluctuations satisfy the central limit theorem.Comment: 28 pages, LaTeX 2

Scheduling non-urgent patient transportation while maximizing emergency coverage

Many ambulance providers operate both advanced life support (ALS) and basic life support (BLS) ambulances. Typically, only an ALS ambulance can respond to an emergency call, whereas non-urgent patient transportation requests can be served by either an ALS or a BLS ambulance. The total capacity of BLS ambulances is usually not enough to fulfill all non-urgent transportation requests. The remaining transportation requests then have to be performed by ALS ambulances, which reduces the coverage for emergency calls. We present a model that determines the routes for BLS ambulances while maximizing the remaining coverage by ALS ambulances. Different from the classical dial-a-ride problem, only one patient can be transported at a time, and not all requests are known in advance. Throughout the day, new requests arrive, and we present an online model to deal with these requests

Gravitational diffraction radiation

We show that if the visible universe is a membrane embedded in a higher-dimensional space, particles in uniform motion radiate gravitational waves because of spacetime lumpiness. This phenomenon is analogous to the electromagnetic diffraction radiation of a charge moving near to a metallic grating. In the gravitational case, the role of the metallic grating is played by the inhomogeneities of the extra-dimensional space, such as a hidden brane. We derive a general formula for gravitational diffraction radiation and apply it to a higher-dimensional scenario with flat compact extra dimensions. Gravitational diffraction radiation may carry away a significant portion of the particle's initial energy. This allows to set stringent limits on the scale of brane perturbations. Physical effects of gravitational diffraction radiation are briefly discussed.Comment: 5 pages, 2 figures, RevTeX4. v2: References added. Version to appear in Phys. Rev.

Bordetella avium cross-reacts with B. bronchiseptica by ELISA but natural B. avium infection in rats is unlikely

The specificity of a Bordetella bronchiseptica antibody ELISA for the monitoring of laboratory rodents  was re-evaluated by studying the serological relationship of the B. bronchiseptica antigen and antigens of  B. avium, B. hinzii, B. holmesii and an unclassified Bordetella sp. Immunization of rats with B. avium  strains induced antibodies to the B. bronchiseptica antigen. Bordetella antibody free rats that were experimentally  infected with a B. avium strain seroconverted to the bacterium but not to B. bronchiseptica and  were B. avium culture positive at one week postinfection but not at 6 weeks. Pathogen free rats exposed to  the B. avium infected rats remained free from any cultural or serological evidence of B. avium infection.  Lung lesions were not seen in experimentally infected and exposed rats. Natural B. avium infection in rats  therefore seems unlikely.

Traveling-wave deceleration of SrF molecules

We report on the production, deceleration and detection of a SrF molecular beam. The molecules are captured from a supersonic expansion and are decelerated in the X$^2\Sigma^+ (v=0, N=1)$ state. We demonstrate the removal of up to 40% of the kinetic energy with a 2 meter long modular traveling-wave decelerator. Our results demonstrate a crucial step towards the preparation of ultracold gases of heavy diatomic molecules for precision spectroscopy