Twin-tunnelling-induced ground movements in clay

Modern tunnelling methods aim to reduce ground movements arising from the construction process. In clay strata the usual method of construction is by tunnel boring machine, which allows close control of the tunnelling process; however, any movements have the potential to cause damage to existing structures at, and below, the ground surface. The construction of underground rail systems often comprises two tunnels running in opposite directions. Common practice for assessing construction-generated movements around these tunnels is to make predictions based upon individual tunnel construction and utilise superposition to generate a total deformation profile. This approach does not take into account the strain- or stress-dependent effects between tunnel constructions. A delay may result in unanticipated ground movements generated by the construction of the second tunnel. The effect of this delay on the ground movements arising between the first and the second tunnel construction process was investigated in a series of plane strain centrifuge tests. The ground movements at and below the surface were monitored and were assessed against superposition-based predictions for surface settlement with the outcomes highlighting some inconsistencies. A procedure for predicting both surface and subsurface vertical settlement profiles in the plane transverse to the advancing tunnels in clay is suggested

Apparatus for centrifuge modelling of twin-tunnel construction

In urban areas it is common for pairs of tunnels to be used as a method for building rapid transit systems. Driven by an increasing population and demand for services, tunnels are more widespread in their use than at any previous time. Construction of any form of tunnel causes ground movements which have the potential to damage existing surface and sub-surface structures. Modern tunnelling practice aims to reduce these movements to a minimum but there is still a requirement for accurate assessments of possible damage to structures resulting from settlements. For tunnels driven in clay, superposition of settlement predictions made by considering a single tunnel is an accepted method used to estimate movements around pairs of tunnels. Previous research, particularly numerical studies, has indicated that this may not necessarily be sufficient. In this paper a series of centrifuge model tests designed to investigate settlements related to twin-tunnel construction are described. The development of the experimental apparatus for sequential twin-tunnel construction with variable centre-to-centre spacing and volume loss is described in detail

Convulsive liability of bupropion hydrochloride metabolites in Swiss albino mice

<p>Abstract</p> <p>Background</p> <p>It is known that following chronic dosing with bupropion HCl active metabolites are present in plasma at levels that are several times higher than that of the parent drug, but the possible convulsive effects of the major metabolites are not known.</p> <p>Methods</p> <p>We investigated the convulsive liability and dose-response of the three major bupropion metabolites following intraperitoneal administration of single doses in female Swiss albino mice, namely erythrohydrobupropion HCl, threohydrobupropion HCl, and hydroxybupropion HCl. We compared these to bupropion HCl. The actual doses of the metabolites administered to mice (n = 120; 10 per dose group) were equimolar equivalents of bupropion HCl 25, 50 and 75 mg/kg. Post treatment, all animals were observed continuously for 2 h during which the number, time of onset, duration and intensity of convulsions were recorded. The primary outcome variable was the percentage of mice in each group who had a convulsion at each dose. Other outcome measures were the time to onset of convulsions, mean convulsions per mouse, and the duration and intensity of convulsions.</p> <p>Results</p> <p>All metabolites were associated with a greater percentage of seizures compared to bupropion, but the percentage of convulsions differed between metabolites. Hydroxybupropion HCl treatment induced the largest percentage of convulsing mice (100% at both 50 and 75 mg/kg) followed by threohydrobupropion HCl (50% and 100%), and then erythrohydrobupropion HCl (10% and 90%), compared to bupropion HCl (0% and 10%). Probit analysis also revealed the dose-response curves were significantly different (p < 0.0001) with CD₅₀values of 35, 50, 61 and 82 mg/kg, respectively for the four different treatments. Cox proportional hazards model results showed that bupropion HCl, erythrohydrobupropion HCl, and threohydrobupropion HCl were significantly less likely to induce convulsions within the 2-h post treatment observation period compared to hydroxybupropion HCl. The mean convulsions per mouse also showed the same dose-dependent and metabolite-dependent trends.</p> <p>Conclusion</p> <p>The demonstration of the dose-dependent and metabolite-dependent convulsive effects of bupropion metabolites is a novelty.</p

Ecological Study of HIV Infection and Hypertension in Sub-Saharan Africa: Is There a Double Burden of Disease?

An ecological correlation study of the prevalence of hypertension with human immunodeficiency virus (HIV) prevalence in sub-Saharan Africa was conducted to determine the extent to which these conditions coincide at country level. Data on prevalence of hypertension were derived from a systematic search of literature published between 1975 and 2014 with corresponding national estimates on HIV prevalence and antiretroviral therapy (ART) coverage from the Demographic and Health Surveys and the joint United Nations Programme on HIV/AIDS databases. National estimates on gross national income (GNI) and under-five mortality were obtained from the World Bank database. Linear regression analyses using robust standard errors (allowing for clustering at country level) were carried out for associations of age-standardised hypertension prevalence ratios (standardized to rural Uganda’s hypertension prevalence data) with HIV prevalence, adjusted for national indicators, year of study and sex of the study population. In total, 140 estimates of prevalence of hypertension representing 25 nations were sex-and area-matched with corresponding HIV prevalence. A two-fold increase in HIV prevalence was associated with a 9.29% increase in age, sex and study year-adjusted prevalence ratio for hypertension (95% CI 2.0 to 16.5, p = 0.01), which increased to 16.3% (95% CI 9.3 to 21.1) after adjusting for under-five mortality, GNI per capita and ART coverage. Countries with a pronounced burden of HIV may also have an increased burden of non-communicable diseases such as hypertension with potential economic and health systems implications

Priority setting: what constitutes success? A conceptual framework for successful priority setting

BACKGROUND: The sustainability of healthcare systems worldwide is threatened by a growing demand for services and expensive innovative technologies. Decision makers struggle in this environment to set priorities appropriately, particularly because they lack consensus about which values should guide their decisions. One way to approach this problem is to determine what all relevant stakeholders understand successful priority setting to mean. The goal of this research was to develop a conceptual framework for successful priority setting. METHODS: Three separate empirical studies were completed using qualitative data collection methods (one-on-one interviews with healthcare decision makers from across Canada; focus groups with representation of patients, caregivers and policy makers; and Delphi study including scholars and decision makers from five countries). RESULTS: This paper synthesizes the findings from three studies into a framework of ten separate but interconnected elements germane to successful priority setting: stakeholder understanding, shifted priorities/reallocation of resources, decision making quality, stakeholder acceptance and satisfaction, positive externalities, stakeholder engagement, use of explicit process, information management, consideration of values and context, and revision or appeals mechanism. CONCLUSION: The ten elements specify both quantitative and qualitative dimensions of priority setting and relate to both process and outcome components. To our knowledge, this is the first framework that describes successful priority setting. The ten elements identified in this research provide guidance for decision makers and a common language to discuss priority setting success and work toward improving priority setting efforts

Working conditions and public health risks in slaughterhouses in western Kenya

Background: Inadequate facilities and hygiene at slaughterhouses can result in contamination of meat and occupational hazards to workers. The objectives of this study were to assess current conditions in slaughterhouses in western Kenya and the knowledge, and practices of the slaughterhouse workers toward hygiene and sanitation. Methods: Between February and October 2012 all consenting slaughterhouses in the study area were recruited. A standardised questionnaire relating to facilities and practices in the slaughterhouse was administered to the foreperson at each site. A second questionnaire was used to capture individual slaughterhouse workers’ knowledge, practices and recent health events. Results: A total of 738 slaughterhouse workers from 142 slaughterhouses completed questionnaires. Many slaughterhouses had poor infrastructure, 65% (95% CI 63–67%) had a roof, cement floor and walls, 60% (95% CI 57–62%) had a toilet and 20% (95% CI 18–22%) had hand-washing facilities. The meat inspector visited 90% (95% CI 92–95%) of slaughterhouses but antemortem inspection was practiced at only 7% (95% CI 6–8%). Nine percent (95% CI 7–10%) of slaughterhouses slaughtered sick animals. Only half of workers wore personal protective clothing - 53% (95% CI 51–55%) wore protective coats and 49% (95% CI 46–51%) wore rubber boots. Knowledge of zoonotic disease was low with only 31% (95% CI 29–33%) of workers aware that disease could be transmitted from animals. Conclusions: The current working conditions in slaughterhouses in western Kenya are not in line with the recommendations of the Meat Control Act of Kenya. Current facilities and practices may increase occupational exposure to disease or injury and contaminated meat may enter the consumer market. The findings of this study could enable the development of appropriate interventions to minimise public health risks. Initially, improvements need to be made to facilities and practices to improve worker safety and reduce the risk of food contamination. Simultaneously, training programmes should target workers and inspectors to improve awareness of the risks. In addition, education of health care workers should highlight the increased risks of injury and disease in slaughterhouse workers. Finally, enhanced surveillance, targeting slaughterhouse workers could be used to detect disease outbreaks. This “One Health” approach to disease surveillance is likely to benefit workers, producers and consumers

ATHENA detector proposal - a totally hermetic electron nucleus apparatus proposed for IP6 at the Electron-Ion Collider

ATHENA has been designed as a general purpose detector capable of delivering the full scientific scope of the Electron-Ion Collider. Careful technology choices provide fine tracking and momentum resolution, high performance electromagnetic and hadronic calorimetry, hadron identification over a wide kinematic range, and near-complete hermeticity.This article describes the detector design and its expected performance in the most relevant physics channels. It includes an evaluation of detector technology choices, the technical challenges to realizing the detector and the R&D required to meet those challenges