Cosmic Ray Acceleration by Spiral Shocks in the Galactic Wind

Cosmic ray acceleration by shocks related with Slipping Interaction Regions (SIRs) in the Galactic Wind is considered. SIRs are similar to Solar Wind Corotating Interaction Regions. The spiral structure of our Galaxy results in a strong nonuniformity of the Galactic Wind flow and in SIR formation at distances of 50 to 100 kpc. SIRs are not corotating with the gas and magnetic field because the angular velocity of the spiral pattern differs from that of the Galactic rotation. It is shown that the collective reacceleration of the cosmic ray particles with charge $Ze$ in the resulting shock ensemble can explain the observable cosmic ray spectrum beyond the "knee" up to energies of the order of $10^{17}Z$ eV. For the reaccelerated particles the Galactic Wind termination shock acts as a reflecting boundary.Comment: LATEX, 14 pages, 7 figures, accepted to A&

The Fermi Bubble as a Source of Cosmic Rays in the Energy Range > 10E15 eV

The {\it Fermi} Large Area Telescope has recently discovered two giant gamma-ray bubbles which extend north and south of the Galactic center with diameters and heights of the order of $H\sim 10$ kpc. We suggest that the periodic star capture processes by the Galactic supermassive black hole Sgr A$^*$, with a capture rate of $\tau_{\rm cap}^{-1}\sim 3\times 10^{-5}$ yr$^{-1}$ and an energy release of $W\sim 3\times 10^{52}$ erg per capture, can result in hot plasma injecting into the Galactic halo at a wind velocity of $u\sim 10^8$ cm s$^{-1}$. The periodic injection of hot plasma can produce a series of shocks. Energetic protons in the bubble are re-accelerated when they interact with these shocks. We show that for energy larger than $E> 10^{15}$ eV, the acceleration process can be better described by the stochastic second-order Fermi acceleration. We propose that hadronic cosmic rays (CRs) within the ``knee'' of the observed CR spectrum are produced by Galactic supernova remnants distributed in the Galactic disk. Re-acceleration of these particles in the Fermi Bubble produces CRs beyond the knee. With a mean CR diffusion coefficient in this energy range in the bubble $D_B\sim 3\times 10^{30}$ cm$^2$ s$^{-1}$, we can reproduce the spectral index of the spectrum beyond the knee and within. The conversion efficiency from shock energy of the bubble into CR energy is about 10\%. This model provides a natural explanation of the observed CR flux, spectral indices, and matching of spectra at the knee.Comment: 43 pages, 8 figues, to be published in the Astrophysical Journal; version 2, 45 pages, 8 figures, added references and corrected typo

Careers in ecstasy use: do ecstasy users cease of their own accord? Implications for intervention development

<p>Abstract</p> <p>Background</p> <p>Ecstasy (MDMA, 3, 4-methylenodioxymethamphetamine) use is widespread in the Netherlands, with a lifetime prevalence of 4.3%, and two-thirds of dance party visitors being ecstasy users. However, research into Dutch ecstasy use patterns is lacking. In addition, recent studies suggest that ecstasy users cease their use automatically, which implies that interventions would do better to better focus on the promotion of harm reduction strategies than on inducing cessation. The current study addresses this process of ecstasy cessation.</p> <p>Methods</p> <p>32 participants from the Dutch dance scene were interviewed, and the results were systematically analysed using NVivo.</p> <p>Results</p> <p>Most ecstasy users had started to use out of curiosity. During use, users applied a host of harm reduction strategies, albeit inconsistently and sometimes incorrectly. Most users appeared to cease ecstasy use automatically because of loss of interest or changing life circumstances (e.g. a new job or relationship).</p> <p>Conclusion</p> <p>It appears that cessation of ecstasy use is largely determined by environmental variables and not by health concerns. This supports the idea that health promotion resources are better spent in trying to promote consistent and correct application of harm reduction practices than in trying to induce cessation.</p

Surveillance of HIV infections among drug users; a feasibility study in Deventer

Abstract niet beschikbaarIn the western world, intravenous drug users are the second most important risk group for AIDS after homosexual men with multiple partners. Because of the long incubation period of AIDS, research on the prevalence of HIV in risk groups can lead to a considerable gain in time with regard to the formulation of care and prevention policies. Until now in the Netherlands prevalence studies among drug users have almost exclusively been done in Amsterdam. Therefore, little is known about the spread of HIV among drug users across the country. This study was initiated to investigate the feasibility of (regularly repeated) prevalence studies among drug users. Of special importance was to ascertain to what extent drug users in general and hidden groups in particular could be reached using care facilities as an entrance. Apart from that the study generates data on prevalence of HIV infections and HIV-related risk factors in a population of drug users outside the urbanized Western part of the country. In this study a recently developed saliva test for antibodies against HIV is used. It was attempted to reach all hard-drug users, both injecting and non-injecting, in the population. This was done to be able to study selections, that occur when studying sub-populations, and to be able to study sexual risk behaviour independently of risk related to injection of drugs. Deventer, a provincial town in the Eastern part of the country, was selected as research site on the basis of population size, the number and type of care facilities, and comparability with a simultaneous project among drug users in Alkmaar. The most important findings are: 1 Given the fruitful collaboration prevalence research among drug users, using local care facilities as an entrance is well possible. 2. Prevalence research in collaboration with care facilities can offer advantages with respect to the acceptability for care givers and participants and repeatability. 3. Hidden groups, not reached by care facilities, can still be reached by this approach. Realistic estimates of the number and characteristics of the whole population are possible through nomination techniques. 4. The prevalence of HIV infections among drug users in Deventer is low: 0-2.6% in general and 0-5.3% among intravenous drug users. This low prevalence is probably representative of the prevalence among drug users outside the urbanized Western part of the country. 5. Sharing of needles and syringes is uncommon in Deventer. Sexual risk is more common among women, drug users with little education, and among drug users currently or ever under methadone treatment. Injecting drug users are older, more often have a history of prostitution and make more drug-related travels to other cities.PCCAO WVC (Programma coordinatie Commissie AIDS Onderzoek van de Raad voor Gezondheidsonderzoek

In vitro permeation of chromium species through porcine and human skin as determined by capillary electrophoresis-inductively coupled plasma-sector field mass spectrometry

Since the species that trigger chromium allergy are not yet known, it is important to gain more of an insight into the mechanism of chromium transport through the skin and into the relationship between chromium allergy and chromium species. In vitro permeation studies with porcine and human skin were performed using a Franz static diffusion cell. Investigations attempted to elucidate (i) which Cr compounds are able to permeate through skin, (ii) the influence the Cr concentration in the donor solution has on the Cr permeation, and (iii) the effect that the time of exposure to the donor solution has on Cr permeation. Capillary electrophoresis hyphenated to inductively coupled plasma-sector field mass spectrometry (CE-ICP-SFMS) was used to separate and quantify the Cr species in the receptor fluid. 50 mmol L-1 phosphate buffer (pH 2.5) was used for CE separation, and two different electrophoretic runs were carried out (in the positive and negative modes). Pneumatic nebulization (PN)-ICP-SFMS was used in order to quantify the total amount of Cr absorbed by the skin after microwave-assisted acid digestion of the tissue. Cr(VI) was found to pass most easily through the skin. Nevertheless, Cr(VI) was also shown to be absorbed more efficiently by the skin than Cr(III), an observation attributed to a more pronounced rejection of the positively charged Cr(III) ions by the skin barrier. These results were in good agreement with in vitro permeation studies previously reported in the literature in which other analytical techniques were used. Differences observed in the permeation of Cr following the application of aqueous Cr donor solutions and Cr-containing simulated sweat donor solutions are also described

Training direct care staff working with persons with intellectual disabilities and challenging behaviour: A meta-analytic review study

Two separate meta-analyses were conducted to examine (1) the effects of training programs on the behaviour of direct care staff working with clients with ID who present challenging behaviour problems (predominantly aggressive and violent behaviour), and (2) the effects of staff training on the challenging behaviour of their clients with ID. A 3-level random effects model was used for both meta-analyses to account for both within and between study variance. Results showed that staff training was moderately effective in changing staff behaviour, but no convincing evidence was found for an effect on the reduction of challenging behaviour of persons with ID. The type, content and goal of training did not moderate the effects of staff training, whereas sample and study characteristics (e.g., sex participant or year of publication) did. The way a training program is delivered to staff may be much more important than characteristics of a training