Cohort profile: the Siyakhula cohort, rural South Africa

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Risk factors for excessive gestational weight gain in a UK population: A biopsychosocial model approach

Background Gestational weight gain (GWG) can have implications for the health of both mother and child. However, the contributing factors remain unclear. Despite the advantages of using a biopsychosocial approach, this approach has not been applied to study GWG in the UK. This study aimed to investigate the risk factors of excessive GWG in a UK population, employing a biopsychosocial model. Methods This study utilised data from the longitudinal Grown in Wales (GiW) cohort, which recruited women in late pregnancy in South Wales. Specifically, data was collected from midwife recorded notes and an extensive questionnaire completed prior to an elective caesarean section (ELCS) delivery. GWG was categorised according to Institute of Medicine (IOM) guidelines. The analysis was undertaken for 275 participants. Results In this population 56.0% of women had excessive GWG. Increased prenatal depression symptoms (Exp(B)=1.10, p=.019) and an overweight (Exp(B)=4.16, p<.001) or obese (Exp(B)=4.20, p=.010) pre-pregnancy BMI, consuming alcohol in pregnancy (Exp(B)=.37, p=.005) and an income of less than £18,000 (Exp(B)=.24, p=.043) and £25–43,000 (Exp(B)=.25, p=.002) were associated with excessive GWG. Conclusion GWG is complex and influenced by a range of biopsychosocial factors, with the high prevalence of excessive weight gain in this population a cause for concern. Women in the UK may benefit from a revised approach toward GWG within the National Health Service (NHS), such as tracking weight gain throughout pregnancy. Additionally, this research provides evidence for potential targets for future interventions, and potentially at-risk populations to target, to improve GWG outcomes

Diffusion-Weighted MRI: Distinction of Skull Base Chordoma from Chondrosarcoma

BACKGROUND AND PURPOSE: Chordoma and chondrosarcoma of the skull base are rare tumors with overlapping presentations and anatomic imaging features but different prognoses. We hypothesized that these tumors might be distinguished by using diffusion-weighted MR imaging. MATERIALS AND METHODS: We retrospectively reviewed 19 patients with pathologically confirmed chordoma or chondrosarcoma who underwent both conventional and diffusion-weighted MR imaging. Differences in distributions of ADC were assessed by the Kruskal-Wallis test. Associations between histopathologic diagnosis and conventional MR imaging features (T2 signal intensity, contrast enhancement, and tumor location) were assessed with the Fisher exact test. RESULTS: Chondrosarcoma was associated with the highest mean ADC value (2051 ± 261 × 10−6 mm2/s) and was significantly different from classic chordoma (1474 ± 117 × 10−6 mm2/s) and poorly differentiated chordoma (875 ± 100 × 10−6 mm2/s) (P CONCLUSIONS: Diffusion-weighted MR imaging may be useful in assessing clival tumors, particularly in differentiating chordoma from chondrosarcoma. A prospective study of a larger cohort will be required to determine the value of ADC in predicting histopathologic diagnosis

Joint modelling of multiple network wiews

Latent space models (LSM) for network data were introduced by Hoff et al. (2002) under the basic assumption that each node of the network has an unknown position in a D-dimensional Euclidean latent space: generally the smaller the distance between two nodes in the latent space, the greater their probability of being connected. In this paper we propose a variational inference approach to estimate the intractable posterior of the LSM. In many cases, different network views on the same set of nodes are available. It can therefore be useful to build a model able to jointly summarise the information given by all the network views. For this purpose, we introduce the latent space joint model (LSJM) that merges the information given by multiple network views assuming that the probability of a node being connected with other nodes in each network view is explained by a unique latent variable. This model is demonstrated on the analysis of two datasets: an excerpt of 50 girls from 'Teenage Friends and Lifestyle Study' data at three time points and the Saccharomyces cerevisiae genetic and physical protein-protein interactions

Refining human palaeodietary reconstruction using amino acid delta N-15 values of plants, animals and humans.

An established method of estimating the trophic level of an organism is through stable isotope analysis of its tissues and those of its diet. This method has been used in archaeology to reconstruct past human diet from the stable nitrogen isotope (d15N) values of human and herbivore bone collagen. However, this approach, using the 15N-enrichment of human bone collagen d15N values over associated herbivore bone collagen d15N values to predict the relative importance of animal protein, relies on the assumptions that: (i) the d15N values of plants consumed by humans and herbivores are identical, and (ii) the 15Nenrichment between diet and consumer is consistent. Bone collagen amino acid d15N values have the potential to tackle these uncertainties, as they constrain the factors influencing bone collagen d15N values. In this study, the d15N values of glutamic acid and phenylalanine in human and herbivore bone collagen isolates from Neolithic sites in Germany, Greece and Turkey were determined by gas chromatography-combustion-isotope ratio mass spectrometry. The fraction of animal protein in total dietary protein consumed by the humans was estimated by: (i) comparing bulk human and herbivore collagen d15N values, (ii) comparing bulk human and herbivore collagen and ancient charred cereal grain d15N values, (iii) comparing human bone collagen d15NGlutamic acid and d15NPhenylalanine values, and (iv) comparing d15NGlutamic acid values of human and herbivore bone collagen and estimated d15NGlutamic acid values of ancient charred cereal grains. Where determined cereal grain d15N values are higher than estimated herbivore forage values, estimates of animal protein consumption are significantly lower, emphasising the importance of the plant nitrogen contribution to human bone collagen. This study also highlights the need for further investigation into: (i) the D15NConsumer-Diet values of glutamic acid and phenylalanine in terrestrial ecosystems, and (ii) D15NGlutamic acid-Phenylalanine values of common plant foods in order to improve the accuracy and more widespread applicability of amino acid-based methods for palaeodietary reconstruction

The Hospital Burden Associated With Intergenerational Contact With the Welfare System in Australia

Importance: Intergenerational welfare contact is a policy issue because of the personal and social costs of entrenched disadvantage; yet, few studies have quantified the burden associated with intergenerational welfare contact for health. Objective: To examine the proportion of individuals who experienced intergenerational welfare contact and other welfare contact types and to estimate their cause-specific hospital burden. Design, Setting, and Participants: This cohort study used a whole-of-population linked administrative dataset of individuals followed from birth to age 20 years using deidentified data from the Better Evidence Better Outcomes Linked Data platform (Australian Government Centrelink [welfare payments], birth registration, perinatal birth records, and inpatient hospitalizations). Participants included individuals born in South Australia from 1991 to 1995 and their parents. Analysis was undertaken from January 2020 to June 2022. Exposures: Using Australian Government Centrelink data, welfare contact was defined as 1 or more parents receiving a means-tested welfare payment (low-income, unemployment, disability, or caring) when children were aged 11 to 15 years, or youth receiving payment at ages 16 to 20 years. Intergenerational welfare contact was defined as welfare contact occurring in both parent and offspring generations. Offspring were classified as: no welfare contact, parent-only welfare contact, offspring-only welfare contact, or intergenerational welfare contact. Main Outcomes and Measures: Hospitalization rates and cumulative incidence were estimated by age, hospitalization cause, and welfare contact group. Results: A total of 94 358 offspring (48 589 [51.5%] male) and 143 814 parents were included in analyses. The study population included 32 969 offspring (34.9%) who experienced intergenerational welfare contact. These individuals were more socioeconomically disadvantaged at birth and had the highest hospitalization rate (133.5 hospitalizations per 1000 person-years) compared with individuals with no welfare contact (46.1 hospitalizations per 1000 person-years), individuals with parent-only welfare contact (75.0 hospitalizations per 1000 person-years), and individuals with offspring-only welfare contact (87.6 hospitalizations per 1000 person-years). Hospitalizations were frequently related to injury, mental health, and pregnancy. For example, the proportion of individuals with intergenerational welfare contact who had experienced at least 1 hospitalization at ages 16 to 20 years was highest for injury (9.0% [95% CI, 8.7%-9.3%]). Conclusions and Relevance: In this population-based cohort study, individuals who experienced intergenerational welfare contact represented one-third of the population aged 11 to 20 years. Compared with individuals with parent-only welfare contact, individuals with intergenerational welfare contact were more disadvantaged at birth and had 78% higher hospitalization rates from age 11 to 20 years, accounting for more than half of all hospitalizations. Frequent hospitalization causes were injuries, mental health, and pregnancy. This study provides the policy-relevant estimate for what it could mean to break cycles of disadvantage for reducing hospital burden.Alexandra M. Procter, Catherine R. Chittleborough, Rhiannon M. Pilkington, Odette Pearson, Alicia Montgomerie, John W. Lync

The Dirac system on the Anti-de Sitter Universe

We investigate the global solutions of the Dirac equation on the Anti-de-Sitter Universe. Since this space is not globally hyperbolic, the Cauchy problem is not, {\it a priori}, well-posed. Nevertheless we can prove that there exists unitary dynamics, but its uniqueness crucially depends on the ratio beween the mass $M$ of the field and the cosmological constant $\Lambda>0$ : it appears a critical value, $\Lambda/12$, which plays a role similar to the Breitenlohner-Freedman bound for the scalar fields. When $M^2\geq \Lambda/12$ there exists a unique unitary dynamics. In opposite, for the light fermions satisfying $M^2<\Lambda/12$, we construct several asymptotic conditions at infinity, such that the problem becomes well-posed. In all the cases, the spectrum of the hamiltonian is discrete. We also prove a result of equipartition of the energy.Comment: 33 page

Two Mathematically Equivalent Versions of Maxwell's Equations

This paper is a review of the canonical proper-time approach to relativistic mechanics and classical electrodynamics. The purpose is to provide a physically complete classical background for a new approach to relativistic quantum theory. Here, we first show that there are two versions of Maxwell's equations. The new version fixes the clock of the field source for all inertial observers. However now, the (natural definition of the effective) speed of light is no longer an invariant for all observers, but depends on the motion of the source. This approach allows us to account for radiation reaction without the Lorentz-Dirac equation, self-energy (divergence), advanced potentials or any assumptions about the structure of the source. The theory provides a new invariance group which, in general, is a nonlinear and nonlocal representation of the Lorentz group. This approach also provides a natural (and unique) definition of simultaneity for all observers. The corresponding particle theory is independent of particle number, noninvariant under time reversal (arrow of time), compatible with quantum mechanics and has a corresponding positive definite canonical Hamiltonian associated with the clock of the source. We also provide a brief review of our work on the foundational aspects of the corresponding relativistic quantum theory. Here, we show that the standard square-root and the Dirac equations are actually two distinct spin-$\tfrac{1}{2}$ particle equations.Comment: Appeared: Foundations of Physic