Transitions to Injecting and Risk of Hepatitis C Transmission among Ethnic Vietnamese Heroin Smokers in Melbourne, Australia

Background and Aims: To examine factors associated with transition from non-injecting to injecting routes of drug administration and testing antibody positive to hepatitis C virus (HCV) among ethnic Vietnamese heroin users in Melbourne, Australia. Methods: In a cross-sectional convenience survey, sample recruited by peer-workers using snowball sampling technique with a finger prick blood collection. Two-hundred ethnic Vietnamese heroin users were recruited and interviews conducted mainly in Footscray, an area of high ethnic Vietnamese residency with a prominent street based drug market. A structured questionnaire was administered. Measures included patterns of drug use, transition from smoking to injecting and vice versa, injection related risk behaviours and HCV sero-status. Results: Ninety-three percent of the sample commenced drug use by non-injecting routes of administration. More than a half had made the transition from smoking to injecting and almost two thirds of participants had ever injected. The factors associated with making this transition included being male and a longer duration of use. Prevalence of exposure to HCV among injectors was over 50%. Factors associated with being HCV positive were longer duration of injecting, sharing injecting equipment and being older. Conclusions: Smoking heroin is a common route of drug administration among heroin users of Vietnamese ethnicity in this study. The transition from smoking to injecting was very common in the sample. The need for targeted harm reduction initiatives is indicated, and these must take into account patterns of heroin use as well as the social context of drug use if we are to work effectively with heroin users of Vietnamese ethnicity

Ultrafast Diffusion at the Onset of Growth: O/Ru(0001).

Nanoscopic clustering in a 2D disordered phase is observed for oxygen on Ru(0001) at low coverages and high temperatures. We study the coexistence of quasistatic clusters (with a characteristic length of ∼9  Å) and highly mobile atomic oxygen which diffuses between the energy-inequivalent, threefold hollow sites of the substrate. We determine a surprisingly low activation energy for diffusion of 385±20  meV. The minimum of the O-O interadsorbate potential appears to be at lower separations than previously reported.Isaac Newton Trust, grant 17.37(j) Herchel Smith Fun

Dynamical Model for the Zodiacal Cloud and Sporadic Meteors

The solar system is dusty, and would become dustier over time as asteroids collide and comets disintegrate, except that small debris particles in interplanetary space do not last long. They can be ejected from the solar system by Jupiter, thermally destroyed near the Sun, or physically disrupted by collisions. Also, some are swept by the Earth (and other planets), producing meteors. Here we develop a dynamical model for the solar system meteoroids and use it to explain meteor radar observations. We find that the Jupiter Family Comets (JFCs) are the main source of the prominent concentrations of meteors arriving to the Earth from the helion and antihelion directions. To match the radiant and orbit distributions, as measured by the Canadian Meteor Orbit Radar (CMOR) and Advanced Meteor Orbit Radar (AMOR), our model implies that comets, and JFCs in particular, must frequently disintegrate when reaching orbits with low perihelion distance. Also, the collisional lifetimes of millimeter particles may be longer (>10^5 yr at 1 AU) than postulated in the standard collisional models (10^4 yr at 1 AU), perhaps because these chondrule-sized meteoroids are stronger than thought before. Using observations of the Infrared Astronomical Satellite (IRAS) to calibrate the model, we find that the total cross section and mass of small meteoroids in the inner solar system are (1.7-3.5)x10^11 km^2 and 4x10^19 g, respectively, in a good agreement with previous studies. The mass input required to keep the Zodiacal Cloud (ZC) in a steady state is estimated to be 10^4-10^5 kg/s. The input is up to 10 times larger than found previously, mainly because particles released closer to the Sun have shorter collisional lifetimes, and need to be supplied at a faster rate

Study of lymphoedema of non-filarial origin in the north west region of Cameroon: spatial distribution, profiling of cases and socio-economic aspects of podoconiosis

Background: Although podoconiosis is endemic in Cameroon, little is known about its epidemiology and spatial distribution. Methods: In this cross-sectional, population-based study, we enrolled all adults (≥15 years) residing in the districts of North-West Region of Cameroon for more than 10 or more years. Participants were interviewed, had physical examination. The study outcomes were prevalence estimates lymphoedema and podoconiosis. House-to-house screening was conducted by Community Health Implementers (CHIs). CHIs registered all individuals with lymphoedema and collected additional individual and household-related information. A panel of experts re-examined and validated all lymphoedema cases registered by CHIs. Results: Of the 439,781 individuals registered, 214,195 were adults (≥15 years old) and had lived in the districts of the Region for more than 10 years. A total of 2,143 lymphoedema cases, were identified by CHIs, giving a prevalence of lymphoedema 1.0% (95% confidence interval [CI]; 0.96-1.04) (2,143/214,195). After review by experts, podoconiosis prevalence in the study area was 0.48% (1,049/214,195) (95% CI; 0.46-0.52). The prevalence of podoconiosis varied by health district, from 0.16% in Oku to 1.92% in Bafut (p < 0.05). A total of 374 patients were recruited by stratified random sampling from the validated CHIs’ register to assess the clinical features and socio-economic aspects of the disease. Patients reportedly said to have first noticed swelling at an average age of 41.9 ± 19.1 (range: 6-90 years). Most patients (86.1%) complained of their legs suddenly becoming hot, red and painful. The majority (309, 96.5%) of the interviewees said they had worn shoes occasionally at some point in their life. The reportedly mean age at first shoe wearing was 14.2 ± 10.1 (± Standard Deviation), range (1-77 years). A high proportion (82.8%) of the participants wore shoes at the time of interview. Of those wearing shoes, only 67 (21.7%) were wearing protective shoes. Conclusion: This study provides insight into the geographical distribution and epidemiology of podoconiosis in the North West region of Cameroon, yet management is limited. Evidence-informed targeted interventions are needed to manage people with lymphoedem

Cometary Origin of the Zodiacal Cloud and Carbonaceous Micrometeorites

The zodiacal cloud is a thick circumsolar disk of small debris particles produced by asteroid collisions and comets. Here, we present a zodiacal cloud model based on the orbital properties and lifetimes of comets and asteroids, and on the dynamical evolution of dust after ejection. The model is quantitatively constrained by IRAS observations of thermal emission, but also qualitatively consistent with other zodiacal cloud observations. We find that 85-95% of the observed mid-infrared emission is produced by particles from the Jupiter-family comets (JFCs) and $<$10% by dust from long period comets. Asteroidal dust is found to be present at $<$10%. We suggest that spontaneous disruptions of JFCs, rather than the usual cometary activity driven by sublimating volatiles, is the main mechanism that librates cometary particles into the zodiacal cloud. Our results imply that JFC particles represent $\sim$85% of the total mass influx at Earth. Since their atmospheric entry speeds are typically low ($\approx$14.5 km s$^{-1}$ mean for D=100-200 $\mu$m with $\approx$12 km s$^{-1}$ being the most common case), many JFC grains should survive frictional heating and land on the Earth's surface. This explains why most micrometeorites collected in antarctic ice have primitive carbonaceous composition. The present mass of the inner zodiacal cloud at $<$5 AU is estimated to be 1-$2\times10^{19}$ g, mainly in D=100-200 $\mu$m particles. The inner zodiacal cloud should have been $>10^4$ times brighter during the Late Heavy Bombardment (LHB) epoch $\approx$3.8 Gyr ago, when the outer planets scattered numerous comets into the inner solar system. The bright debris disks with a large 24-$\mu$m excess observed around mature stars may be an indication of massive cometary populations existing in those systems