Demographic, risk behaviour and personal network variables associated with prevalent hepatitis C, hepatitis B, and HIV infection in injection drug users in Winnipeg, Canada

BACKGROUND: Previous studies have used social network variables to improve our understanding of HIV transmission. Similar analytic approaches have not been undertaken for hepatitis C (HCV) or B (HBV), nor used to conduct comparative studies on these pathogens within a single setting. METHODS: A cross-sectional survey consisting of a questionnaire and blood sample was conducted on injection drug users in Winnipeg between December 2003 and September 2004. Logistic regression analyses were used to correlate respondent and personal network data with HCV, HBV and HIV prevalence. RESULTS: At the multivariate level, pathogen prevalence was correlated with both respondent and IDU risk network variables. Pathogen transmission was associated with several distinct types of high-risk networks formed around specific venues (shooting galleries, hotels) or within users who are linked by their drug use preferences. Smaller, isolated pockets of IDUs also appear to exist within the larger population where behavioural patterns pose a lesser risk, unless or until, a given pathogen enters those networks. CONCLUSION: The findings suggest that consideration of both respondent and personal network variables can assist in understanding the transmission patterns of HCV, HBV, and HIV. It is important to assess these effects for multiple pathogens within one setting as the associations identified and the direction of those associations can differ between pathogens

Data assimilation in the solar wind: challenges and first results

Data Assimilation (DA) is used extensively in numerical weather prediction (NWP) to improve forecast skill. Indeed, improvements in forecast skill in NWP models over the past 30 years have directly coincided with improvements in DA schemes. At present, due to data availability and technical challenges, DA is underused in space weather applications, particularly for solar wind prediction. This paper investigates the potential of advanced DA methods currently used in operational NWP centres to improve solar wind prediction. To develop the technical capability, as well as quantify the potential benefit, twin experiments are conducted to assess the performance of the Local Ensemble Transform Kalman Filter (LETKF) in the solar wind model ENLIL. Boundary conditions are provided by the Wang-Sheeley-Arge coronal model and synthetic observations of density, temperature and momentum generated every 4.5hr at 0.6AU. While in-situ spacecraft observations are unlikely to be routinely available at 0.6AU, these techniques can be applied to remote sensing of the solar wind, such as with Heliospheric Imagers or Interplanetary Scintillation. The LETKF can be seen to improve the state at the observation location and advect that improvement towards the Earth, leading to an improvement in forecast skill in near Earth space for both the observed and unobserved variables. However, sharp gradients caused by the analysis of a single observation in space resulted in artificial wave-like structures being advected towards Earth. This paper is the first attempt to apply DA to solar wind prediction, and provides the first in-depth analysis of the challenges and potential solutions

Brisk walking compared with an individualised medical fitness programme for patients with type 2 diabetes: a randomised controlled trial

AIMS/HYPOTHESIS: Structured exercise is considered a cornerstone in type 2 diabetes treatment. However, adherence to combined resistance and endurance type exercise or medical fitness intervention programmes is generally poor. Group-based brisk walking may represent an attractive alternative, but its long-term efficacy as compared with an individualised approach such as medical fitness intervention programmes is unknown. We compared the clinical benefits of a 12-month exercise intervention programme consisting of either brisk walking or a medical fitness programme in type 2 diabetes patients. METHODS: We randomised 92 type 2 diabetes patients (60 +/- 9 years old) to either three times a week of 60 min brisk walking (n = 49) or medical fitness programme (n = 43). Primary outcome was the difference in changes in HbA1c values at 12 months. Secondary outcomes were differences in changes in blood pressure, plasma lipid concentrations, insulin sensitivity, body composition, physical fitness, programme adherence rate and health-related quality of life. RESULTS: After 12 months, 18 brisk walking and 19 medical fitness participants were still actively participating. In both programmes, 50 and 25% of the dropout was attributed to overuse injuries and lack of motivation, respectively. Intention-to-treat analyses showed no important differences between brisk walking and medical fitness programme in primary or secondary outcome variables. CONCLUSIONS/INTERPRETATION: The prescription of group-based brisk walking represents an equally effective intervention to modulate glycaemic control and cardiovascular risk profile in type 2 diabetes patients when compared with more individualised medical fitness programmes. Future exercise intervention programmes should anticipate the high attrition rate due to overuse injuries and motivation problems

VISIBLENEAR INFRARED (VNIR) AND SHORTWAVE INFRARED (SWIR) SPECTRAL VARIABILITY OF URBAN MATERIALS

The advent of relatively high spatial resolution hyperspectral imagery (HSI) provides a different perspective of the urban environment than lower spatial resolution hyperspectral data and either multispectral or panchromatic images. The objective of this thesis was to build and analyze a spectral library of urban materials and to understand how spectral variability affects the ability of classification algorithms to identify and discriminate various materials. The scope of the project was limited to non-vegetative impervious materials located on the Naval Postgraduate School campus. An airborne hyperspectral image, acquired September 30th 2011 was used for image-derived endmembers and a portable spectroradiometer was used to collect field spectra. Visual analysis of spectra was performed to assess intra- and inter-class variability and to identify spectral features and their causes. The spectral angle mapper (SAM) algorithm was used on the HSI data as a method to quantify intra-class spectral variability using a standard spectral angle. Classification maps were created with both SAM and mixture tuned matched filtering (MTMF) algorithms to determine how intra- and inter-class spectral variability affect the algorithms ability to classify urban materials. The spatially complex nature of the urban environment negatively affected the performance of the SAM algorithm, but the ability to increase the spectral angle to account for materials with high spectral variability allowed improved inter-class discrimination. The MTMF algorithm was better suited for intra-class discrimination of materials.http://archive.org/details/visiblenearinfra1094532816Civilian, Department of the NavyApproved for public release; distribution is unlimited

Improved respiratory muscle endurance of highly trained cyclists and the effects on maximal exercise performance

To study the effects of 4 weeks of isocapnic hyperventilation training on the respiratory muscle (RM) endurance and cycling performance, 10 highly trained male cyclists (VO₂max = 66 +. 5 ml/kg/min) were assigned to equal experimental (E) and control (C) groups. The following measurements were obtained for each subject both the hyperpnea training period: maximal sustained ventilatory capacity (MSVC), maximal oxygen consumption (VO₂max), maximal exercise ventilation (V[sub E]max), a performance cycle test at 90% VO₂max (tlim), maximal ventilation during tlim (V[sub E]tlim), Forced expiratory volume in one second (FEV₁), Forced vital capacity (FVC), and Maximum voluntary ventilation in 12 seconds (MVV₁₂). For the E group, the training consisted of three, 8 minute intervals of hyperpnea per session, 4 times a week. Following training, the MSVC of the experimental subjects increased significantly (155.4 ± 11 to 173.9 + 12 1/min; p = 0.004) with no change for the control group (155.1 ± 26 vs 149.5 ± 34 1/min, p > 0.05). VO₂max was not significantly changed for the E group (64.2 ± 1.9 vs 65.8 ± 4.8 ml/kg/min, p > 0.05) nor for the C group (68.0 ± 6.6 vs 67.1 ± 5.8 ml/kg/min, p > 0.05). Similarly, no significant differences were observed for tlim (342.2 ± 75 vs 427.8 ± 226.1 sec for the E group and 328.6 ± 99 vs 342.4 ± 80 sec for the C group, p > 0.05). There were also no significant changes for either the E group or for the C group for the measurements of V[sub E]max (177.0 ± 22 vs 177.1 ± 13 1/min; 171.4 ± 36 vs 167.5 ± 21 1/min); V[sub E]tlim (176.0 ± 16 vs 178.5 ± 19 1/min; 174.0 ± 29 vs 176.3 ± 27 1/min); FEV, (4.4 ± 0.3 vs 4.5 ± 0.4 1/; 4.8 ± 0.6 vs 4.7 ± 0.7 1); FVC (5.5 ± 0.9 vs 5.7 ± 1.0 1; 5.7 ± 0.7 vs 5.6 ± 0.7 1); or MVV₁₂ ( 205.5 ± 15 vs 216.3 ± 19 1/min; 215.2 ± 20 vs 223.3 ± 26 1/min, all p > 0.05). Results of this study indicate that the RM endurance of highly trained male cyclists can be increased following specific hyperpnea training but this does not result in changes in maximal exercise performance.Education, Faculty ofCurriculum and Pedagogy (EDCP), Department ofGraduat