Escort tug at large yaw angle: comparison of CFD predictions with experimental data

Escort tugs operate at high yaw angles in order to produce forces to steer and stop the vessel they are escorting in an emergency. In this paper, RANS predictions of forces and flow patterns around the hull of an escort tug model are compared with experimental data. Two alternative meshing strategies were used, one using tetrahedral elements with triangular faces and one using hexahedral elements with quadrilateral faces. Experiments were carried out with and without the low aspect ratio fin that is typical of many escort tugs. Lift and drag forces were measured experimentally for yaw angles from 15 to 45 degrees. Flow measurements around the tug at 45 degrees yaw were obtained using a stereoscopic particle image velocimetry (PIV) system. The results from each CFD simulation were compared to the measured flow patterns using a numerical procedure that led to a quantitative measure of the accuracy of the predicted results. The analysis of the flow patterns indicated that the main features of the flow were predicted, and that on average, the predicted velocity magnitudes were within 10% of the measured values. Neither mesh approach had a significant effect on the accuracy of the flow pattern predictions. The hexahedral mesh gave more accurate force predictions that the tetrahedral mesh. Forces were predicted by the CFD code with this mesh to within 5 % of the experimentally obtained values

Flow Vectors Around an Escort Tug at a Large Yaw Angle

The flow around a ship at yaw angles beyond those encountered during manoeuvres has not been the subject of much research reported in the literature. These conditions are particularly important for an escort tug, since it uses large yaw angles to generate hydrodynamic forces that are used to control a ship (normally a tanker) in the event of an emergency. This paper presents CFD predictions for the flow around an escort tug at a yaw angle of 45 degrees and compares them to PIV measurements of the flow patterns. The CFD code predicts the essential features measured within the flow, such as the separation of the flow from the upstream bilge, and the formation of a large vortex generated by the low aspect ratio fin. The predicted vectors were compared with the measured ones using a numerical technique, and the agreements were found, on average, to be within 10%. This level of agreement was within the estimated uncertainty of the PIV system used for the experiments

Case Report - A 6 year-old boy was referred from a district hospital with congestive cardiac failure

No Abstract

The burden of mental health in lymphatic filariasis.

BACKGROUND Neglected Tropical Diseases (NTDs) afflict around one billion individuals in the poorest parts of the world with many more at risk. Lymphatic filariasis is one of the most prevalent of the infections and causes significant morbidity in those who suffer the clinical conditions, particularly lymphedema and hydrocele. Depressive illness has been recognised as a prevalent disability in those with the disease because of the stigmatising nature of the condition. No estimates of the burden of depressive illness of any neglected tropical disease have been undertaken to date despite the recognition that such diseases have major consequences for mental health not only for patients but also their caregivers. METHODS We developed a mathematical model to calculate the burden of Disability- Adjusted Life Years (DALY) attributable to depressive illness in lymphatic filariasis and that of their caregivers using standard methods for calculating DALYs. Estimates of numbers with clinical disease was based on published estimates in 2012 and the numbers with depressive illness from the available literature. RESULTS We calculated that the burden of depressive illness in filariasis patients was 5.09 million disability-adjusted life years (DALYs) and 229,537 DALYs attributable to their caregivers. These figures are around twice that of 2.78 million DALYs attributed to filariasis by the Global Burden of Disease study of 2010. CONCLUSIONS Lymphatic filariasis and other neglected tropical diseases, notably Buruli Ulcer, cutaneous leishmaniasis, leprosy, yaws, onchocerciasis and trachoma cause significant co morbidity associated with mental illness in patients. Studies to assess the prevalence of the burden of this co-morbidity should be incorporated into any future assessment of the Global Burden of neglected tropical diseases. The prevalence of depressive illness in caregivers who support those who suffer from these conditions is required. Such assessments are critical for neglected tropical diseases which have such a huge global prevalence and thus will contribute a significant burden of co-morbidity attributable to mental illness

Evidence of Rise in Rabies Cases in Southern Malawi – Better Preventative Measures Are Urgently Required

We describe five children who died of clinical rabies in a three month period (September to November 2011) in the Queen Elizabeth Central Hospital. From previous experience and hospital records, this number of cases is higher than expected. We are concerned that difficulty in accessing post-exposure prophylaxis (PEP) rabies vaccine may be partly responsible for this rise. We advocate: (a) prompt course of active immunisation for all patients with significant exposure to proven or suspected rabid animals. (b) the use of an intradermal immunisation regime that requires a smaller quantity of the vaccine than the intramuscular regime and gives a better antibody response. (c) improved dog rabies control measure

Profile: The Kilifi Health and Demographic Surveillance System (KHDSS).

The Kilifi Health and Demographic Surveillance System (KHDSS), located on the Indian Ocean coast of Kenya, was established in 2000 as a record of births, pregnancies, migration events and deaths and is maintained by 4-monthly household visits. The study area was selected to capture the majority of patients admitted to Kilifi District Hospital. The KHDSS has 260 000 residents and the hospital admits 4400 paediatric patients and 3400 adult patients per year. At the hospital, morbidity events are linked in real time by a computer search of the population register. Linked surveillance was extended to KHDSS vaccine clinics in 2008. KHDSS data have been used to define the incidence of hospital presentation with childhood infectious diseases (e.g. rotavirus diarrhoea, pneumococcal disease), to test the association between genetic risk factors (e.g. thalassaemia and sickle cell disease) and infectious diseases, to define the community prevalence of chronic diseases (e.g. epilepsy), to evaluate access to health care and to calculate the operational effectiveness of major public health interventions (e.g. conjugate Haemophilus influenzae type b vaccine). Rapport with residents is maintained through an active programme of community engagement. A system of collaborative engagement exists for sharing data on survival, morbidity, socio-economic status and vaccine coverage

A Trial of a 7-Valent Pneumococcal Conjugate Vaccine in HIV-Infected Adults.

BACKGROUND: Streptococcus pneumoniae is a leading and serious coinfection in adults with human immunodeficiency virus (HIV) infection, particularly in Africa. Prevention of this disease by vaccination with the current 23-valent polysaccharide vaccine is suboptimal. Protein conjugate vaccines offer a further option for protection, but data on their clinical efficacy in adults are needed. METHODS: In this double-blind, randomized, placebo-controlled clinical efficacy trial, we studied the efficacy of a 7-valent conjugate pneumococcal vaccine in predominantly HIV-infected Malawian adolescents and adults who had recovered from documented invasive pneumococcal disease. Two doses of vaccine were given 4 weeks apart. The primary end point was a further episode of pneumococcal infection caused by vaccine serotypes or serotype 6A. RESULTS: From February 2003 through October 2007, we followed 496 patients (of whom 44% were male and 88% were HIV-seropositive) for 798 person-years of observation. There were 67 episodes of pneumococcal disease in 52 patients, all in the HIV-infected subgroup. In 24 patients, there were 19 episodes that were caused by vaccine serotypes and 5 episodes that were caused by the 6A serotype. Of these episodes, 5 occurred in the vaccine group and 19 in the placebo group, for a vaccine efficacy of 74% (95% confidence interval [CI], 30 to 90). There were 73 deaths from any cause in the vaccine group and 63 in the placebo group (hazard ratio in the vaccine group, 1.18; 95% CI, 0.84 to 1.66). The number of serious adverse events within 14 days after vaccination was significantly lower in the vaccine group than in the placebo group (3 vs. 17, P=0.002), and the number of minor adverse events was significantly higher in the vaccine group (41 vs. 13, P=0.003). CONCLUSIONS: The 7-valent pneumococcal conjugate vaccine protected HIV-infected adults from recurrent pneumococcal infection caused by vaccine serotypes or serotype 6A. (Current Controlled Trials number, ISRCTN54494731.) Copyright 2010 Massachusetts Medical Society

Decoding neuronal ensembles in the human hippocampus

BACKGROUND: The hippocampus underpins our ability to navigate, to form and recollect memories, and to imagine future experiences. How activity across millions of hippocampal neurons supports these functions is a fundamental question in neuroscience, wherein the size, sparseness, and organization of the hippocampal neural code are debated. RESULTS: Here, by using multivariate pattern classification and high spatial resolution functional MRI, we decoded activity across the population of neurons in the human medial temporal lobe while participants navigated in a virtual reality environment. Remarkably, we could accurately predict the position of an individual within this environment solely from the pattern of activity in his hippocampus even when visual input and task were held constant. Moreover, we observed a dissociation between responses in the hippocampus and parahippocampal gyrus, suggesting that they play differing roles in navigation. CONCLUSIONS: These results show that highly abstracted representations of space are expressed in the human hippocampus. Furthermore, our findings have implications for understanding the hippocampal population code and suggest that, contrary to current consensus, neuronal ensembles representing place memories must be large and have an anisotropic structure