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

Secondary polycythaemia with elevated carbon monoxide levels due to hookah pipe smoking: A public health concern.

Hookah pipe (HP) smoking is perceived as a harmless activity, enjoyed by young adults and high school-going children. Awareness of the health impact of recreational habits, and their intersection with new social norms in the COVID-era, requires critical review. We describe a case series of young HP smokers presenting with secondary polycythaemia with significant clinical sequelae necessitating extensive work-up. HP smoking may lead to acute and chronic carbon monoxide intoxication, with resultant secondary polycythaemia and complications including provoked thrombosis

'We did everything we could'- A qualitative study exploring the acceptability of maternal-fetal surgery for spina bifida to parents

OBJECTIVE: To explore the concepts and strategies parents employ when considering maternal-fetal surgery (MFS) as an option for the management of spina bifida (SB) in their fetus, and how this determines the acceptability of the intervention. METHODS: A two-centre interview study enrolling parents whose fetuses with SB were eligible for MFS. To assess differences in acceptability, parents opting for MFS (n=24) were interviewed at three different moments in time: prior to the intervention, directly after the intervention and 3-6 months after birth. Parents opting for termination of pregnancy (n=5) were interviewed only once. Themes were identified and organised in line with the framework of acceptability. RESULTS: To parents opting for MFS, the intervention was perceived as an opportunity that needed to be taken. Feelings of parental responsibility drove them to do anything in their power to improve their future child's situation. Expectations seemed to be realistic yet were driven by hope for the best outcome. None expressed decisional regret at any stage, despite substantial impact and, at times, disappointing outcomes. For the small group of participants, who decided to opt for termination of pregnancy (TOP), MFS was not perceived as an intervention that substantially could improve the quality of their future child's life. CONCLUSION: Prospective parents opting for MFS were driven by their feelings of parental responsibility. They recognise the fetus as their future child and value information and care focusing on optimising the child's future health. In the small group of parents opting for TOP, MFS was felt to offer insufficient certainty of substantial improvement in quality of life and the perceived severe impact of SB drove their decision to end the pregnancy This article is protected by copyright. All rights reserved

Sourcing the ore from the Drierivier copper smelting site in central Namibia, using lead isotope fingerprinting

Copper smelting residues from C. AD 1650 found at the Drierivier site near Rehoboth in central Namibia have 207Pb/206Pb isotope ratios that match a particular deposit at Swartmodder, but are markedly different from other known occurrences in the Rehoboth–Windhoek areas. For this reason, precise lead isotope determination is not necessary to source the ore, and raw peak height ratios obtained by inductively coupled plasma mass spectrometry are sufficient. This characteristic signature is present in all samples of malachite ore, slag, and copper prills collected on the site. Significantly, it is absent from a sample of local native copper, as well as from seven copper beads found elsewhere in central Namibia. This not only identifies the probable source of malachite ore but also provides a powerful tool for provenancing copper artefacts made at the Drierivier site, distinguishing them from those made elsewhere in the Namibian highlands

Ethnic differences in lipid metabolism in two groups of obese South African women

There is a higher prevalence of ischemic heart disease (IHD) in South African white than black women. The objective of this study was to determine biochemical explanations for this prevalence. The study group contained 15 obese black women (OBW) and 14 obese white women (OWW), ah premenopausal, who were examined after an overnight fast. Anthropometric measurements and blood concentrations of glucose, non-esterified fatty acids (NEFAs), catecholamines, plasminogen activator inhibitor-1, C-peptide, proinsulin, lipograms, cortisol, growth hormone, and post-heparin Lipoprotein Lipase activity were measured during an oral glucose tolerance test (OGTT), Body composition was measured using bioelectrical impedance analysis, and subcutaneous and visceral fat mass were assessed with CT-scans. Visceral fat area was higher in OWW (139.7 +/- 10.7 cm(2)) than in OBW (72.3 +/- 3.9 cm(2)) (P < 0.01), as were fasting and 3 h triglyceride concentrations (P < 0.05 for all). OWW also had higher NEFA levels than OBW at 3 and 4 h compared, with OBW (P < 0.05 for both). Fasting cortisol (266 +/- 24 vs. 197 +/- 19 nmol/l; P < 0.05) was higher in OWW than in OBW. These data demonstrate that OWW have higher visceral fat mass than OBW, which may lead to a more atherogenic fasting and postprandial Lipid profile. The higher cortisol levels of the OWW may promote visceral fat deposition. - Punyadeera, C., M-T. van der Merwe, N.J. Crowther, M. Toman, C. P. Schlaphoff, and I. P. Gray. Ethnic differences in lipid metabolism in two groups of obese South African women

Drivers of inter-annual variability in Net Ecosystem Exchange in a semi-arid savanna ecosystem, South Africa

Inter-annual variability in primary production and ecosystem respiration was explored using eddy-covariance data at a semi-arid savanna site in the Kruger Park, South Africa. New methods of extrapolating night-time respiration to the entire day and filling gaps in eddy-covariance data in semi-arid systems were developed. Net ecosystem exchange (NEE) in these systems occurs as pulses associated with rainfall events, a pattern not well-represented in current standard gap-filling procedures developed primarily for temperate flux sites. They furthermore do not take into account the decrease in respiration at high soil temperatures. An artificial neural network (ANN) model incorporating these features predicted measured fluxes accurately (MAE 0.42 gC/m&lt;sup&gt;2&lt;/sup&gt;/day), and was able to represent the seasonal patterns of photosynthesis and respiration at the site. The amount of green leaf area (indexed using satellite-derived estimates of fractional interception of photosynthetically active radiation &lt;i&gt;f&lt;/i&gt;&lt;sub&gt;APAR&lt;/sub&gt;), and the timing and magnitude of rainfall events, were the two most important predictors used in the ANN model. These drivers were also identified by multiple linear regressions (MLR), with strong interactive effects. The annual integral of the filled NEE data was found to range from &amp;minus;138 to +155 g C/m&lt;sup&gt;2&lt;/sup&gt;/y over the 5 year eddy covariance measurement period. When applied to a 25 year time series of meteorological data, the ANN model predicts an annual mean NEE of 75(&amp;plusmn;105) g C/m&lt;sup&gt;2&lt;/sup&gt;/y. The main correlates of this inter-annual variability were found to be variation in the amount of absorbed photosynthetically active radiation (APAR), length of the growing season, and number of days in the year when moisture was available in the soil

Suicide cases investigated at the state mortuary in Bloemfontein, 2003–2007

Background: Up to 8 000 South Africans commit suicide annually. This study aimed to investigate the profile of suicide cases in Bloemfontein and the southern Free State province.Methods: A cross-sectional descriptive study was performed. Suicides in the Bloemfontein and southern Free State areas (Xhariep and Motheo districts) investigated at the state mortuary in Bloemfontein in 2003 to 2007 were included. Data were collected retrospectively by using a specially designed data-capturing form.Results: A total of 469 suicide cases were included in the study. The estimated suicide rate for this part of the Free State province was 10.9/100 000 of the population per year. The majority (82.1%) of the victims were men. In total, 338 (72.1%) of the victims were black, 122 (26.0%) were white, five (1.1%) were coloured and three (0.6%) were Indian. The most common methods were hanging (262; 55.9%), shooting (99; 21.1%) and overdosing on pills (43; 9.2%). Most cases (57.8%) occurred in victims 21 to 40 years of age. Five (1.1%) victims were children younger than 11 years of age, while 12 (2.6%) were older than 65 years. More than half (267 cases; 56.9%) of the suicide victims were unemployed. The majority(43.1%) of suicides occurred in January to April of each year, with the highest incidence (67 cases; 14.3%) in January. Conclusion: The rate of suicide and the profile of victims with regard to the variables investigated corresponded to findings reported from other studies. The information obtained could make a meaningful contribution to suicide-preventionprogrammes.Keywords: suicide; profile; rate; prevention; Free State Provinc

Preanalytical processing of archaeological mammal enamel apatite carbonates for stable isotope investigations: a comparative analysis of the effect of acid treatment on samples from Northwest Australia

Stable isotopic analysis of palaeontological and archaeological biogenic apatite carbonates from herbivorous mammalian species represents an important tool for worldwide palaeoecological research. Tooth enamel carbonates are more resistant to taphonomic processes than bone or dentine carbonates but are not invulnerable to diagenesis. As such, they require careful preanalytical processing that considers depositional environment and age. An established part of this process includes a weak acid treatment to remove soluble exogenous carbonates; however, published treatment times for isotopic studies of archaeological tooth enamel are variable and range from 15\ua0min to over 8\ua0hr. This study tests three different pretreatment protocols on modern and Pleistocene age archaeological kangaroo teeth (dating from contemporary to 46,000 bp) to assess the effect of acid treatment time on isotopic integrity. The results indicate that treatment time is a critical parameter for producing consistency across results and shorter pretreatments of 4\ua0hr or less are preferable for removing diagenetic carbonates while minimising alteration of the biological signal