1,599 research outputs found
Cyclotron radionuclide production for biomedical applications
No full textThe use of High Specific Activity Radionuclides HSARNs, obtained by either proton, deuteron or alpha cyclotron irradiation, followed by selective radiochemical separation from the irradiated target in No Carrier Added (NCA) form, is a powerful analytical tool. The main applications of these radionuclides are to medical diagnosis and therapy in addition to toxicological, environmental and industrial studies. Some examples of production and radioanalytical quality control methods for HSARNs are presented
Drag and inertia coefficients for horizontally submerged rectangular cylinders in waves and currents
No full textThe results of an experimental investigation carried out to measure combined wave and current loads on horizontally submerged square and rectangular cylinders are reported in this paper. The wave and current induced forces on a section of the cylinders with breadth-depth (aspect) ratios equal to 1, 0.5, and 0.75 are measured in a wave tank. The maximum value of Keulegan-Carpenter (KC) number obtained in waves alone is about 5 and Reynolds (Re) number ranged from 6.3976103 to 1.186105. The drag (CD) and inertia (CM) coefficients for each cylinder are evaluated using measured sectional wave forces and particle kinematics calculated from linear wave theory. The values of CD and CM obtained for waves alone have already been reported (Venugopal, V., Varyani, K. S., and Barltrop, N. D. P. Wave force coefficients for horizontally submerged rectangular cylinders. Ocean Engineering, 2006, 33, 11-12, 1669-1704) and the coefficients derived in combined waves and currents are presented here. The results indicate that both drag and inertia coefficients are strongly affected by the presenceof the current and show different trends for different cylinders. The values of the vertical component inertia coefficients (CMY) in waves and currents are generally smaller than the inertia coefficients obtained in waves alone, irrespective of the current's magnitude and direction. The results also illustrate the effect of a cylinder's aspect ratio on force coefficients. This study will be useful in the design of offshore structures whose columns and caissons are rectangular sections
A rare prostaglandin from the soft coral Sarcophyton crassocaule of the Indian Ocean
No full textThe rare prostaglandin methyl (5Z)-9,15-dioxoprosta-5,8(12)-dien-1-oate (1), hitherto unreported as a natural product, has been isolated from the Indian Ocean soft coral Sarcophyton crassocaule. Its structure was elucidated using detailed spectral (H-1 and C-13 NMR, DEPT, H-H COSY, C-H COSY, HRMS, and HMBC) analysis
Geographic determinants of reported human Campylobacter infections in Scotland
No full text<p><b>Background:</b> Campylobacteriosis is the leading cause of bacterial gastroenteritis in most developed countries. People are exposed to infection from contaminated food and environmental sources. However, the translation of these exposures into infection in the human population remains incompletely understood. This relationship is further complicated by differences in the presentation of cases, their investigation, identification, and reporting; thus, the actual differences in risk must be considered alongside the artefactual differences.</p>
<p><b>Methods:</b> Data on 33,967 confirmed Campylobacter infections in mainland Scotland between 2000 and 2006 (inclusive) that were spatially referenced to the postcode sector level were analysed. Risk factors including the Carstairs index of social deprivation, the easting and northing of the centroid of the postcode sector, measures of livestock density by species and population density were tested in univariate screening using a non-spatial generalised linear model. The NHS Health Board of the case was included as a random effect in this final model. Subsequently, a spatial generalised linear mixed model (GLMM) was constructed and age-stratified sensitivity analysis was conducted on this model.</p>
<p><b>Results:</b> The spatial GLMM included the protective effects of the Carstairs index (relative risk (RR) = 0.965, 95% Confidence intervals (CIs) = 0.959, 0.971) and population density (RR = 0.945, 95% CIs = 0.916, 0.974. Following stratification by age group, population density had a significant protective effect (RR = 0.745, 95% CIs = 0.700, 0.792) for those under 15 but not for those aged 15 and older (RR = 0.982, 95% CIs = 0.951, 1.014). Once these predictors have been taken into account three NHS Health Boards remain at significantly greater risk (Grampian, Highland and Tayside) and two at significantly lower risk (Argyll and Ayrshire and Arran).</p>
<p><b>Conclusions:</b> The less deprived and children living in rural areas are at the greatest risk of being reported as a case of Campylobacter infection. However, this analysis cannot differentiate between actual risk and heterogeneities in individual reporting behaviour; nevertheless this paper has demonstrated that it is possible to explain the pattern of reported Campylobacter infections using both social and environmental predictors.</p>
A numerical investigation of flame lift-off in diesel jets
No full textFlame lift-off heights are modeled in diesel jets by using diffusion flamelet extinction as a criterion for identifying the lift-off. It is shown that the axial distance in the jet where the stoichiometric scalar dissipation rate matches computed extinction scalar dissipation rate correlates with the lift-off height. The influence of injection pressures (40–138 MPa), chamber densities (14.8–58.5 kg/m³), chamber temperatures (1000–1300 K) and O₂ molar concentrations (10–21%) are studied. N-heptane is chosen as a surrogate for diesel fuel. Two chemical kinetic mechanisms, a 37-species, 56-step mechanism and a 159-species, 1540-step mechanism, are employed. Consistent with experimental findings, the computed results indicate that the flame lift-off height decreases with increase in chamber temperature, chamber density and oxygen concentration and increases when the injection velocity is increased. It is observed that across the range of chamber conditions considered, the computed extinction scalar dissipation rates correlate well with the measured lift-off heights. When chamber temperatures and O₂ concentrations are varied, the results are found to be sensitive to the choice of the chemical kinetic mechanism.Rishikesh Venugopal and John Abraha
Venugopal K R [PDF] from computerresearch.org A Novel Approach to Detect Malicious User Node by Cognition in Heterogeneous Wireless Networks
No full textCognitive Networks are characterized by their intelligence and adaptability. Securing layered heterogeneous network architectures has always posed a major challenge to researchers. In this paper, the Observe, Orient, Decide and Act (OODA) loop is adopted to achieve cognition. Intelligence is incorporated by the use of discrete time dynamic neural networks. The use of dynamic neural networks is considered, to monitor the instantaneous changes that occur in heterogeneous network environments when compared to static neural networks. Malicious user node identification is achieved by monitoring the service request rates generated to the cognitive servers. The results and the experimental study presented in this paper prove the improved efficiency in terms of malicious node detection and malicious transaction classification when compared to the existing systems
Electrocardiogram and echocardiographic study of left ventricular hypertrophy in patients with essential hypertension in a teaching medical college
No full textBackground: Left ventricular hypertrophy (LVH) is the adaptive mechanism for increased left ventricular (LV) stress and is associated with many adverse events. This study was undertaken to study LVH in patients of essential hypertension and to correlate between clinical, electrocardiogram (ECG), and echocardiography (ECHO) in the identification of LVH. Materials and Methods: One hundred patients attending the outpatient department and those who were admitted in our teaching institute from January 2013 to June 2014 were the study subjects. All cases of essential hypertension, irrespective of the duration of hypertension and type of treatment received were included in the study. Patients with secondary hypertension, ischemic heart disease/myocardial infarction, ischemic cardiomyopathy, congenital heart disease, and valvular heart disease were excluded. Conclusion: Out of the different ECG criteria, total QRS criteria showed a high sensitivity of 60%. ECG criteria have a high specificity but low sensitivity and hence, have limited use as a screening method. However, in a resource-poor country such as India where ECHO facilities are not available in all rural regions, improved ECG criteria such as total QRS voltage can be recommended as a routine investigation for LVH because of its cost-effectiveness and easy availability despite certain limitations
Grid-enabling FIRST: Speeding up simulation applications using WinGrid
No full textThe vision of grid computing is to make computational power, storage capacity, data and applications available to users as readily as electricity and other utilities. Grid infrastructures and applications have traditionally been geared towards dedicated, centralized, high performance clusters running on UNIX flavour operating systems (commonly referred to as cluster-based grid computing). This can be contrasted with desktop-based grid computing which refers to the aggregation of non-dedicated, de-centralized, commodity PCs connected through a network and running (mostly) the Microsoft Windowstrade operating system. Large scale adoption of such Windowstrade-based grid infrastructure may be facilitated via grid-enabling existing Windows applications. This paper presents the WinGridtrade approach to grid enabling existing Windowstrade based commercial-off-the-shelf (COTS) simulation packages (CSPs). Through the use of a case study developed in conjunction with Ford Motor Company, the paper demonstrates how experimentation with the CSP Witnesstrade and FIRST can achieve a linear speedup when WinGridtrade is used to harness idle PC computing resources. This, combined with the lessons learned from the case study, has encouraged us to develop the Web service extensions to WinGridtrade. It is hoped that this would facilitate wider acceptance of WinGridtrade among enterprises having stringent security policies in place
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