Evolution of dispersion in the cosmic deuterium abundance

Deuterium is created during Big Bang Nucleosynthesis, and, in contrast to the other light stable nuclei, can only be destroyed thereafter by fusion in stellar interiors. In this paper we study the cosmic evolution of the deuterium abundance in the interstellar medium and its dispersion using realistic galaxy evolution models. We find that models that reproduce the observed metal abundance are compatible with observations of the deuterium abundance in the local ISM and z ~ 3 absorption line systems. In particular, we reproduce the low astration factor which we attribute to a low global star formation efficiency. We calculate the dispersion in deuterium abundance arising from different structure formation histories in different parts of the Universe. Our model also predicts an extremely tight correlation between deuterium and metal abundances which could be used to measure the primordial deuterium abundance.Comment: 6 pages, 5 figures. Accepted for publication in MNRAS Letters. Figures rearranged to match published versio

The origin of dispersion in DLA metallicities

Recent chemical abundance measurements of damped Ly-alpha absorbers (DLAs) revealed an intrinsic scatter in their metallicity of ~0.5 dex out to z~5. In order to explore the origin of this scatter, we build a semi-analytic model which traces the chemical evolution of the interstellar matter in small regions of the Universe with different mean density, from over- to underdense regions. We show that the different histories of structure formation in these regions, namely halo abundance, mass and stellar content, is reflected in the chemical properties of the protogalaxies, and in particular of DLAs. We calculate mean metallicity-redshift relations and show that the metallicity dispersion arising from this environmental effect amounts to ~0.25 dex and is an important contributor to the observed overall intrinsic scatter.Comment: 6 pages, 2 figures. Accepted for publication in MNRAS Letter

The management of lending risk in Irish community credit unions

Traditional loan assessment carried out by credit unions has been centred on the members’ history of savings and loan repayment record with their credit union. This has been in keeping with the member-owned, voluntary, self-help co-operative principles of credit unions in providing financial services to their members. In more recent times, Irish credit unions have been challenged to adopt a more formal approach to managing lending risk management in the context of a changed economic and regulatory environment. This paper examines lending risk management and its associated governance in four community credit unions in Ireland during two points in time. The first is between 2008 and 2012, a period marked by economic recession and traditional loan assessment. It then examines the revised approach to lending risk management adopted by credit unions post 2012 following a series of legislative and regulatory change for credit unions where more formal risk management processes and enhanced governance were introduced. It was found that lending by credit unions which maintained prudent management of loan risk outperformed lending by credit unions which took a less prudent approach. In addition, the study demonstrates how the application of risk management principles to the lending process can bring a level of clarity and a structure to loan underwriting, thereby enhancing the quality of the process. Good governance principles can positively influence the lending process and should provide the basis for a sound lending environment

Exact string background from a WZW model based on the Heisenberg group

A WZW model for the non-semi-simple D-dimensional Heisenberg group, which directly generalizes the E_{2}^{c} group, is constructed. It is found to correspond to an D-dimensional string background of plane-wave type with physical Lorentz signature D-2. Perturbative and non-perturbative considerations lead both to an integer central charge c=D.Comment: 9 pages, LATEX, THEF-NYM 94.

Allegory and animals in Olive Schreiner’s Undine : A Queer Little Child (1929)

Written and abandoned in the 1870s, and published posthumously in 1929, Undine: A Queer Little Child has remained on the margins of Olive Schreiner (1855-1920) studies, repeatedly dismissed as a juvenile and poor antecedent to The Story of An African Farm (1883), or deemed valuable primarily for its autobiographical content. This article redresses these schematic readings by analysing how Schreiner draws on allegorical forms in order to explore aspects of her burgeoning radicalism. Focusing on one of the main allegorical thrusts of the novel, provided by the zoomorphic and anthropomorphic animal characters that descend from mythical, fairytale, and Ancient Greek philosophical origins, it investigates how the protagonist’s metaphorically significant associations with animals relate to freethinking, feminist, and anti-imperialist ideas introduced by the novel. Undine thus undermines dominant nineteenth-century models of the “primitive” human or animal as less evolutionarily developed and without political platform, which can be seen to be a liberating move when the novel is read in dialogue with Jacques Derrida’s lectures on animals, and with other recent work in postcolonial ecocriticism

Human Immunodeficiency Virus Nephropathy in Central Africa: The Value of Renal Ultrasound

Introduction: HIV-Associated Nephropathy may shorten the life expectancy of affected patients. Its early detection is beneficial for the indication of treatment and hence prevention of progression to the end-stage of renal failure. The final diagnosis requires renal biopsy which may be difficult in some African area; clinical and ultrasound criteria may be helpful. The aim of this study was twofold: to characterize renal sonographic changes in HIV-positive patients with HIV associated Nephropathy and to investigate the correlation between renal sonographic changes and histological lesions in central Africa.Methods: A prospective and multi-center study conducted from January 2013 to July 2015 included, for renal ultrasound evaluation of the length, thickness and echogenicity, forty two of the 334 biologically confirmed HIV-positive patients who presented with significant proteinuria suggestive of HIV associated Nephropathy. And transcutaneous renal biopsy with histopathology has been performed in 16 patients of them. Statistical analyzes were used.Results: There were 100 men and 234 women; proteinuria was positive in 42 patients, (12.6%). The average length of the kidneys was 111 ± 8 mm (normal), with 10% of patients with pathological values (5% with kidneys of reduced size and 5%, increased size). The kidneys had an average thickness of 44 ± 5 mm (normal), with 21% of patients presenting an increase in renal thickness. Quantitative echogenicity was calculated at 1.492 ± 0.793 (normal), with 79% of patients with increased quantitative echogenicity. Of the 16 patients biopsied, all had tubulo-interstitial lesions, and 75% of them associated with glomerular lesions. In simple correlation analysis, tubular dilatation was positively and significantly related to quantitative echogenicity (r = 0.67, p < 0.01) and to renal parenchyma thickness (r = 0.67; 0.85, p ? 0.05). The relationship between the other parameters studied did not reach statistical significance. In multiple linear regression, glomerular hyalinosis, glomerular proliferation, tubular dilatation, tubular atrophy, interstitial fibrosis, and interstitial inflammation emerged as the main determinants of quantitative echogenicity; however, the relationship was statistically significant only for tubular dilatation (? = 0.305, p = 0.034).Conclusion: The present study showed the characteristic of renal change and the relation with histology found in central Africans patients

Higher D or Li: Probes of Physics beyond the Standard Model

Standard Big Bang Nucleosynthesis at the baryon density determined by the microwave anisotropy spectrum predicts an excess of \li7 compared to observations by a factor of 4-5. In contrast, BBN predictions for D/H are somewhat below (but within ~2 \sigma) of the weighted mean of observationally determined values from quasar absorption systems. Solutions to the \li7 problem which alter the nuclear processes during or subsequent to BBN, often lead to a significant increase in the deuterium abundance consistent with the highest values of D/H seen in absorption systems. Furthermore, the observed D/H abundances show considerable dispersion. Here, we argue that those systems with D/H \simeq 4 \times 10^{-5} may be more representative of the primordial abundance and as a consequence, those systems with lower D/H would necessarily have been subject to local processes of deuterium destruction. This can be accounted for by models of cosmic chemical evolution able to destroy in situ Deuterium due to the fragility of this isotope.Comment: 22 pages, 8 figure

BPS String Solutions in Non-Abelian Yang-Mills Theories and Confinement

Starting from the bosonic part of N=2 Super QCD with a 'Seiberg-Witten' N=2 breaking mass term, we obtain string BPS conditions for arbitrary semi-simple gauge groups. We show that the vacuum structure is compatible with a symmetry breaking scheme which allows the existence of Z_k-strings and which has Spin(10) -> SU(5) x Z_2 as a particular case. We obtain BPS Z_k-string solutions and show that they satisfy the same first order differential equations as the BPS string for the U(1) case. We also show that the string tension is constant, which may cause a confining potential between monopoles increasing linearly with their distance.Comment: 11 pages, Latex. Minor changes to the text. Final version to appear in Phys. Rev.

Interventions to reduce pedestrian road traffic injuries: A systematic review of randomized controlled trials, cluster randomized controlled trials, interrupted time-series, and controlled before-after studies

BACKGROUND: Road traffic injuries are among the top ten causes of death globally, with the highest burden in low and middle-income countries, where over a third of deaths occur among pedestrians and cyclists. Several interventions to mitigate the burden among pedestrians have been widely implemented, however, the effectiveness has not been systematically examined. OBJECTIVES: To assess the effectiveness of interventions to reduce road traffic crashes, injuries, hospitalizations and deaths among pedestrians. METHODS: We considered studies that evaluated interventions to reduce road traffic crashes, injuries, hospitalizations and/or deaths among pedestrians. We considered randomized controlled trials, interrupted time-series studies, and controlled before-after studies. We searched MEDLINE, EMBASE, Web of Science, WHO Global Health Index, Health Evidence, Transport Research International Documentation and ClinicalTrials.gov through 31 August 2020, and the reference lists of all included studies. Two reviewers independently screened titles and abstracts and full texts, extracted data and assessed the risk of bias. We summarized findings narratively with text and tables. RESULTS: A total of 69123 unique records were identified through the searches, with 26 of these meeting our eligibility criteria. All except two of these were conducted in high-income countries and most were from urban settings. The majority of studies observed either a clear effect favoring the intervention or an unclear effect potentially favoring the intervention and these included: changes to the road environment (19/27); changes to legislation and enforcement (12/12); and road user behavior/education combined with either changes to the road environment (3/3) or with legislation and enforcement (1/1). A small number of studies observed either a null effect or an effect favoring the control. CONCLUSIONS: Although the highest burden of road traffic injuries exists in LMICs, very few studies have examined the effectiveness of available interventions in these settings. Studies indicate that road environment, legislation and enforcement interventions alone produce positive effects on pedestrian safety. In combination with or with road user behavior/education interventions they are particularly effective in improving pedestrian safety