Correlates of Hepatitis C Serostatus Disclosure in Rural Appalachian Kentucky

Aim: To identify demographic, behavioral, and interpersonal characteristics associated with hepatitis C (HCV) serostatus disclosure among adult, rural, high-risk people who use drugs (PWUD) in Appalachian Kentucky. Methods: Laboratory confirmed HCV antibody-positive participants (n=243), drawn from the fifth follow-up assessment of a longitudinal study of rural PWUD, completed interviewer-administered questionnaires eliciting demographic and interpersonal characteristics, risk behaviors, and information on HCV disclosure. Correlates of HCV disclosure were assessed using logistic regression. Results: Most (69.1%) reported disclosing their HCV-positive status to at least one of their social referents (current or past sex partners, current or past injection drug use (IDU) partners, family, friends, or spouse), but few told the people with whom they inject drugs (3.8% disclosed to current, and 1.4% disclosed to past IDU partners). In multivariate analysis, adjusting for confounders and time since HCV diagnosis, male gender (AOR=0.40, 95% CI [0.20, 0.78]), older age (AOR=0.96, 95% CI [0.92, 1.00]), lifetime history of injection drug use (AOR=0.26, 95% CI [0.07, 0.99]), and lifetime history of drug treatment (AOR=0.34, 95% CI [0.18, 0.65]) were associated with decreased odds of HCV disclosure. Conclusions: While most participants reported HCV disclosure, the almost complete absence of disclosure to current or former injection drug use partners was concerning. Although further research is warranted, it is clear that interventions are needed to encourage HCV disclosure among those most at risk of transmitting, or becoming infected with, HCV

Laser-Induced, Polarization Dependent Shape Transformation of Au/Ag Nanoparticles in Glass

Bimetallic, initially spherical Ag/Au nanoparticles in glass prepared by ion implantation have been irradiated with intense femtosecond laser pulses at intensities still below the damage threshold of the material surface. This high-intensity laser processing produces dichroism in the irradiated region, which can be assigned to the observed anisotropic nanoparticle shapes with preferential orientation of the longer particle axis along the direction of laser polarization. In addition, the particle sizes have considerably been increased upon processing

The influence of potassium on core and geodynamo evolution

We model the thermal evolution of the core and mantle using a parametrized convection scheme, and calculate the entropy available to drive the geodynamo as a function of time. The cooling of the core is controlled by the rate at which the mantle can remove heat. Rapid core cooling favours the operation of a geodynamo but creates an inner core that is too large; slower cooling reduces the inner core size but makes a geodynamo less likely to operate. Introducing potassium into the core retards inner core growth and provides an additional source of entropy. For our nominal model parameters, a core containing approximate to 400 ppm potassium satisfies the criteria of present-day inner core size, surface heat flux, mantle temperature and cooling rate, and positive core entropy production.We have identified three possibilities that may allow the criteria to be satisfied without potassium in the core. (1) The core thermal conductivity is less than half the generally accepted value of 50 W m(-1) K-1. (2) The core solidus and adiabat are significantly colder and shallower than results from shock experiments and ab initio simulations indicate. (3) The core heat flux has varied by no more than a factor of 2 over Earth history. All models we examined with the correct present-day inner core radius have an inner core age of < 1.5 Gyr; prior to this time the geodynamo was sustained by cooling and radioactive heat production within a completely liquid core

The Flow Of Granular Matter Under Reduced-Gravity Conditions

To gain a better understanding of the surfaces of planets and small bodies in the solar system, the flow behavior of granular material for various gravity levels is of utmost interest. We performed a set of reduced-gravity measurements to analyze the flow behavior of granular matter with a quasi-2D hourglass under coarse-vacuum conditions and with a tilting avalanche box. We used the Bremen drop tower and a small centrifuge to achieve residual-gravity levels between 0.01 g and 0.3 g. Both experiments were carried out with basalt and glass grains as well as with two kinds of ordinary sand. For the hourglass experiments, the volume flow through the orifice, the repose and friction angles, and the flow behavior of the particles close to the surface were determined. In the avalanche-box experiment, we measured the duration of the avalanche, the maximum slope angle as well as the width of the avalanche as a function of the gravity level.Comment: Accepted by "Proc. Powders and Grains 2009", Publisher AI

Photospheric magnetic structure of coronal holes

In this study, we investigate in detail the photospheric magnetic structure of 98 coronal holes using line-of-sight magnetograms of SDO/HMI, and for a subset of 42 coronal holes using HINODE/SOT G-band filtergrams. We divided the magnetic field maps into magnetic elements and quiet coronal hole regions by applying a threshold at $\pm 25$ G. We find that the number of magnetic bright points in magnetic elements is well correlated with the area of the magnetic elements (cc=$0.83\pm 0.01$). Further, the magnetic flux of the individual magnetic elements inside coronal holes is related to their area by a power law with an exponent of $1.261\pm 0.004$ (cc=$0.984\pm 0.001$). Relating the magnetic elements to the overall structure of coronal holes, we find that on average ($69\pm 8$) % of the overall unbalanced magnetic flux of the coronal holes arises from long-lived magnetic elements with lifetimes > 40 hours. About ($22\pm 4$) % of the unbalanced magnetic flux arises from a very weak background magnetic field in the quiet coronal hole regions with a mean magnetic field density of about 0.2 to 1.2 G. This background magnetic field is correlated to the flux of the magnetic elements with lifetimes of > 40 h (cc=$0.88\pm 0.02$). The remaining flux arises from magnetic elements with lifetimes < 40 hours. By relating the properties of the magnetic elements to the overall properties of the coronal holes, we find that the unbalanced magnetic flux of the coronal holes is completely determined by the total area that the long-lived magnetic elements cover (cc=$0.994\pm 0.001$)

3-Phase Evolution of a Coronal Hole, Part I: 360{\deg} remote sensing and in-situ observations

We investigate the evolution of a well-observed, long-lived, low-latitude coronal hole (CH) over 10 solar rotations in the year 2012. By combining EUV imagery from STEREO-A/B and SDO we are able to track and study the entire evolution of the CH having a continuous 360$\deg$ coverage of the Sun. The remote sensing data are investigated together with in-situ solar wind plasma and magnetic field measurements from STEREO-A/B, ACE and WIND. From this we obtain how different evolutionary states of the CH as observed in the solar atmosphere (changes in EUV intensity and area) affect the properties of the associated high-speed stream measured at $1$AU. Most distinctly pronounced for the CH area, three development phases are derived: a) growing, b) maximum, and c) decaying phase. During these phases the CH area a) increases over a duration of around three months from about $1 \cdot 10^{10} \mathrm{km}^{2}$ to $6 \cdot 10^{10} \mathrm{km}^{2}$, b) keeps a rather constant area for about one month of $> 9 \cdot 10^{10} \mathrm{km}^{2}$, and c) finally decreases in the following three months below $1 \cdot 10^{10} \mathrm{km}^{2}$ until the CH cannot be identified anymore. The three phases manifest themselves also in the EUV intensity and in in-situ measured solar wind proton bulk velocity. Interestingly, the three phases are related to a different range in solar wind speed variations and we find for the growing phase a range of $460-600$~km~s$^{-1}$, for the maximum phase $600-720$~km~s$^{-1}$, and for the decaying phase a more irregular behavior connected to slow and fast solar wind speed of $350-550$~km~s$^{-1}$.Comment: Accepted for publication in Ap