Scattering in three-dimensional fuzzy space

We develop scattering theory in a non-commutative space defined by a $su(2)$ coordinate algebra. By introducing a positive operator valued measure as a replacement for strong position measurements, we are able to derive explicit expressions for the probability current, differential and total cross-sections. We show that at low incident energies the kinematics of these expressions is identical to that of commutative scattering theory. The consequences of spacial non-commutativity are found to be more pronounced at the dynamical level where, even at low incident energies, the phase shifts of the partial waves can deviate strongly from commutative results. This is demonstrated for scattering from a spherical well. The impact of non-commutativity on the well's spectrum and on the properties of its bound and scattering states are considered in detail. It is found that for sufficiently large well-depths the potential effectively becomes repulsive and that the cross-section tends towards that of hard sphere scattering. This can occur even at low incident energies when the particle's wave-length inside the well becomes comparable to the non-commutative length-scale.Comment: 12 pages, 6 figure

Spectrum of the three dimensional fuzzy well

We develop the formalism of quantum mechanics on three dimensional fuzzy space and solve the Schr\"odinger equation for a free particle, finite and infinite fuzzy wells. We show that all results reduce to the appropriate commutative limits. A high energy cut-off is found for the free particle spectrum, which also results in the modification of the high energy dispersion relation. An ultra-violet/infra-red duality is manifest in the free particle spectrum. The finite well also has an upper bound on the possible energy eigenvalues. The phase shifts due to scattering around the finite fuzzy potential well have been calculated

A simulation study to compare reference and other priors in the case of a standard univariate Student t-distribution

In this paper, reference and probability-matching priors are derived for the univariate Student t-distribution. These priors generally lead to procedures with properties frequentists can relate to while still retaining Bayes validity. The priors are tested by performing simulation studies. The focus is on the relative mean squared error from the posterior median and on the frequentist coverage of the 95% credibility intervals for a sample of size n = 30. Average interval lengths of the credibility intervals as well as the modes of the interval lengths based on 2 000 simulations are also considered. The performance of the priors is also tested on real data, namely daily logarithmic returns of IBM stocks

Interpreting social determinants: Emergent properties and adolescent risk behaviour

A link between adversity, including low socio-economic status, and behaviours which carry health risks, such as alcohol consumption, has often been observed. The causes of this link are, however, poorly understood, making it difficult to explain why the association is often not linear and why there is so much variability between groups and individuals facing similar adversity. We investigate the use of the concept of emergent properties in explaining the link and its non-linear nature. `Emergent properties’ arise from the interaction of factors or items in a high-level system which, as a result, has qualities possessed by none of the individual factors. We apply a mixed methods approach to examine the association of an example emergent property, hope, and alcohol consumption among adolescents in a rural South African site. We found that among adolescents living in similar contexts, there was enough variance in reported levels of hope, that an association with alcohol use could be identified. This result is cause for optimism regarding the potential use of emergent properties in explaining variations in risk behaviour. Improving our measurement of emergent properties is perhaps the biggest challenge facing this approach. More work is needed to take further the task of identifying emergent properties capable of distilling the influence of lower level variables into single measures useful for analysis and policy purposes

Genera of phytopathogenic fungi: GOPHY 3

This paper represents the third contribution in the Genera of Phytopathogenic Fungi (GOPHY) series. The series provides morphological descriptions, information about the pathology, distribution, hosts and disease symptoms for the treated genera, as well as primary and secondary DNA barcodes for the currently accepted species included in these. This third paper in the GOPHY series treats 21 genera of phytopathogenic fungi and their relatives including: Allophoma, Alternaria, Brunneosphaerella, Elsinoe, Exserohilum, Neosetophoma, Neostagonospora, Nothophoma, Parastagonospora, Phaeosphaeriopsis, Pleiocarpon, Pyrenophora, Ramichloridium, Seifertia, Seiridium, Septoriella, Setophoma, Stagonosporopsis, Stemphylium, Tubakia and Zasmidium. This study includes three new genera, 42 new species, 23 new combinations, four new names, and three typifications of older names

Vaginal birth after caesarean section (VBAC): exploring women's perceptions

yesAims and objectives.  This study was designed to complement local audit data by examining the lived experience of women who elected to attempt a vaginal birth following a previous caesarean delivery. The study sought to determine whether or not women were able to exercise informed choice and to explore how they made decisions about the method of delivery and how they interpreted their experiences following the birth. Background.  The rising operative birth rate in the UK concerns both obstetricians and midwives. Although the popular press has characterized birth by caesarean section as the socialites’ choice, in reality, maternal choice is only one factor in determining the method of birth. However, in considering the next delivery following a caesarean section, maternal choice may be a significant indicator. While accepted current UK practice favours vaginal birth after caesarean (VBAC) in line with the research evidence indicating reduced maternal morbidity, lower costs and satisfactory neonatal outcomes, Lavender et al. point out that partnership in choice has emerged as a key factor in the decision-making process over the past few decades. Chaung and Jenders explored the issue of choice in an earlier study and concluded that the best method of subsequent delivery, following a caesarean birth, is dependent on a woman's preference. Design and methodology.  Using a phenomenological approach enabled a holistic exploration of women's lived experiences of vaginal birth after the caesarean section. Results.  This was a qualitative study and, as such, the findings are not transferable to women in general. However, the results confirmed the importance of informed choice and raised some interesting issues meriting the further exploration. Conclusions.  Informed choice is the key to effective women-centred care. Women must have access to non-biased evidence-based information in order to engage in a collaborative partnership of equals with midwives and obstetricians. Relevance to clinical practice.  This study is relevant to clinical practice as it highlights the importance of informed choice and reminds practitioners that, for women, psycho-social implications may supersede their physical concerns about birth

Mortality trends in the City of Cape Town between 2001 and 2013: Reducing inequities in health

Background. The City of Cape Town (CoCT), South Africa, has collected cause-of-death data from death certificates for many years to monitor population health. In 2000, the CoCT and collaborators set up a local mortality surveillance system to provide timeous mortality data at subdistrict level. Initial analyses revealed large disparities in health across subdistricts and directed the implementation of public health interventions aimed at reducing these disparatities.Objectives. To describe the changes in mortality between 2001 and 2013 in health subdistricts in the CoCT.Methods. Pooled mortality data for the periods 2001 - 2004 and 2010 - 2013, from a local mortality surveillance system in the CoCT, were analysed by age, gender, cause of death and health subdistrict. Age-specific mortality rates for each period were calculated and age-standardised using the world standard population, and then compared across subdistricts.Results. All-cause mortality in the CoCT declined by 8% from 938 to 863 per 100 000 between 2001 - 2004 and 2010 - 2013. Mortality in males declined more than in females owing to a large reduction in male injury mortality, particularly firearm-related homicide. HIV/AIDS and tuberculosis (TB) mortality dropped by ~10% in both males and females, but there was a marked shift to older ages. Mortality in children aged <5 years dropped markedly, mostly owing to reductions in HIV/AIDS and TB mortality. Health inequities between subdistricts were reduced, with the highest-burden subdistricts achieving the largest reductions in mortality.Conclusions. Local mortality surveillance provides important data for planning, implementing and evaluating targeted health interventions at small-area level. Trends in mortality over the past decade indicate some gains in health and equity, but highlight the need for multisectoral interventions to focus on HIV and TB and homicide and the emerging epidemic of non-communicable diseases.

Security sector reform in Africa: donor approaches versus local needs

Many African states have security sector reform (SSR) programs. These are often internationally funded. But how do such programs account for previously existing security institutions and the security needs of local communities? This article examines SSR all over Africa to assess local ownership and path dependency from a New Institutionalist perspective. It finds that SSR, particularly in post-conflict countries, tends to be driven by ideas and perceptions of international donors promoting generalized blueprints. Often, such programs only account in a very limited way for path-dependent aspects of security institutions or the local context. Hence the reforms often lack local participation and are thus not accepted by the local community eventually