Evaluation of the optical conductivity tensor in terms of contour integrations

For the case of finite life-time broadening the standard Kubo-formula for the optical conductivity tensor is rederived in terms of Green's functions by using contour integrations, whereby finite temperatures are accounted for by using the Fermi-Dirac distribution function. For zero life-time broadening, the present formalism is related to expressions well-known in the literature. Numerical aspects of how to calculate the corresponding contour integrals are also outlined.Comment: 8 pages, Latex + 2 figure (Encapsulated Postscript

Examination of a Parent-Assisted, Friendship-Building Program for Adolescents With ADHD

Objective: Youth with ADHD experience significant impairment in peer functioning. Based on recommendations from the literature, the current pilot study examined the effectiveness of a parent-assisted, friendship-building program at establishing mutual friendships and improving peer relationships in adolescents with ADHD. Method: Participants included 20 adolescents with ADHD (ages 11-16 years) and their parent(s). Families completed the Program for the Evaluation and Enrichment of Relational Skills (PEERS). Measures of friendship quality, social knowledge, social self-efficacy, get-togethers, and peer conflict were completed at baseline and post-treatment. At post-treatment, participants also reported on the initiation of a new friendship. Results: Baseline to post-treatment differences were examined using paired-samples t tests. The majority of participants reported the initiation of a new friendship at post-treatment. Adolescents also demonstrated significantly improved social knowledge and increased get-togethers. Effect sizes were large. Conclusion: Following participation in PEERS, adolescents improved in several peer functioning domains and many initiated new friendships

Maternal Functioning Differences Based on ADHD Subtype

Objective: Maternal functioning differences in parenting stress, parental efficacy, and parenting behaviors were examined for mothers of children with ADHD. Method: Participants included 29 mothers of children with ADHD, Predominantly Inattentive Type (ADHD-I) and 38 mothers of children with ADHD, Predominantly Hyperactive-Impulsive or Combined Type (ADHD-HI/C). Results: Findings suggest that mothers of children with ADHD-HI/C reported significantly greater parenting stress and engaged in more negative parenting behaviors than mothers of children with ADHD-I. Conclusion: This study suggests that tailoring behavioral parent training based on ADHD subtype may be particularly helpful for parents of children with ADHD-HI/C

A New Ultra-dense Group of Obscured Emission-Line Galaxies

We present the discovery of an isolated compact group of galaxies that is extremely dense (median projected galaxy separation: 6.9 kpc), has a very low velocity dispersion ($\sigma_{\rm 2D}$ = 67 km s$^{-1}$), and where all observed members show emission lines and are morphologically disturbed. These properties, together with the lack of spirals and the presence of a prominent tidal tail make this group one of the most evolved compact groups.Comment: 15 pages,LaTeX, 2figures. A Postscript figure with spectra is available at ftp://astro.uibk.ac.at/pub/weinberger/ . Accepted for publication in ApJ Letter

A bacterial facultative parasite of Gracilaria conferta

Bacterial epiphytes of Gracilaria conferta were quantified. Saprophytic bacteria reached 350 times and agar degraders 25000 times higher numbers g-1 algal wet wt on tissues infected with the 'white tips disease', as compared to healthy tissues. A bacterial inducing agent of the 'white tips disease' was detected. Addition of 10(2) to 10(3) cells of this isolate ml-1 medium led to increased rates of infection. This effect did not occur if the isolate was autoclaved before addition. The virulent bacteria could always be isolated from infected tissues. It frequently, but not always, infected G. conferta and should be regarded as a facultative parasite. Several factors influenced the disease development. Temperatures above 20-degrees-C, in combination with photon flux densities of more than 200 muE m-2 s-1, increased the rate of infection. Relatively low amounts (more than 25 mug ml-1) of certain organic nutrients (peptone and yeast extract) led to strong manifestations of the disease. Addition of agar did not cause any symptoms, while 5 mg l-1 of the antibiotic rifampicin prevented the alga from being infected

Magnetic properties of Quantum Corrals from first principles calculations

We present calculations for electronic and magnetic properties of surface states confined by a circular quantum corral built of magnetic adatoms (Fe) on a Cu(111) surface. We show the oscillations of charge and magnetization densities within the corral and the possibility of the appearance of spin--polarized states. In order to classify the peaks in the calculated density of states with orbital quantum numbers we analyzed the problem in terms of a simple quantum mechanical circular well model. This model is also used to estimate the behaviour of the magnetization and energy with respect to the radius of the circular corral. The calculations are performed fully relativistically using the embedding technique within the Korringa-Kohn-Rostoker method.Comment: 14 pages, 9 figures, submitted to J. Phys. Cond. Matt. special issue on 'Theory and Simulation of Nanostructures

Electrical transport properties of bulk Nic_{c}Fe1−c_{1-c} alloys and related spin-valve systems

Within the Kubo-Greenwood formalism we use the fully relativistic, spin-polarized, screened Korringa-Kohn-Rostoker method together with the coherent-potential approximation for layered systems to calculate the resistivity for the permalloy series Ni$_{c}$Fe$_{1-c}$. We are able to reproduce the variation of the resistivity across the entire series; notably the discontinuous behavior in the vicinity of the structural phase transition from bcc to fcc. The absolute values for the resistivity are within a factor of two of the experimental data. Also the giant magnetoresistance of a series of permalloy-based spin-valve structures is estimated; we are able to reproduce the trends and values observed on prototypical spin-valve structures.Comment: 6 pages, ReVTeX + 4 figures (Encapsulated Postscript), submitted to PR

Optical Coronagraphic Spectroscopy of AU Mic: Evidence of Time Variable Colors?

We present coronagraphic long slit spectra of AU Mic's debris disk taken with the STIS instrument aboard the Hubble Space Telescope (HST). Our spectra are the first spatially resolved, scattered light spectra of the system's disk, which we detect at projected distances between approximately 10 and 45 AU. Our spectra cover a wavelength range between 5200 and 10200 angstroms. We find that the color of AU Mic's debris disk is bluest at small (12-35 AU) projected separations. These results both confirm and quantify the findings qualitatively noted by Krist et al. (2005), and are different than IR observations that suggested a uniform blue or gray color as a function of projected separation in this region of the disk. Unlike previous literature that reported the color of AU Mic's disk became increasingly more blue as a function of projected separation beyond approximately 30 AU, we find the disk's optical color between 35-45 AU to be uniformly blue on the southeast side of the disk and decreasingly blue on the northwest side. We note that this apparent change in disk color at larger projected separations coincides with several fast, outward moving "features" that are passing through this region of the southeast side of the disk. We speculate that these phenomenon might be related, and that the fast moving features could be changing the localized distribution of sub-micron sized grains as they pass by, thereby reducing the blue color of the disk in the process. We encourage follow-up optical spectroscopic observations of the AU Mic to both confirm this result, and search for further modifications of the disk color caused by additional fast moving features propagating through the disk.Comment: Accepted by AJ, 13 pages, 8 figures, 1 tabl

Impact of Pneumococcal Conjugate Vaccines on Pneumonia Hospitalizations in High- and Low-Income Subpopulations in Brazil.

BackgroundPneumococcal conjugate vaccines (PCVs) are being used worldwide. A key question is whether the impact of PCVs on pneumonia is similar in low- and high-income populations. However, most low-income countries, where the burden of disease is greatest, lack reliable data that can be used to evaluate the impact. Data from middle-income countries that have both low- and high-income subpopulations can provide a proxy measure for the impact of the vaccine in low-income countries.MethodsWe evaluated the impact of PCV10 on hospitalizations for all-cause pneumonia in Brazil, a middle-income country with localities that span a broad range of human development index (HDI) levels. We used complementary time series and spatiotemporal methods (synthetic controls and hierarchical Bayesian spatial regression) to test whether the decline in pneumonia hospitalizations associated with vaccine introduction varied across the socioeconomic spectrum.ResultsWe found that the declines in all-cause pneumonia hospitalizations in children and young and middle-aged adults did not vary substantially across low and high HDI subpopulations. Moreover, the estimated declines seen in infants and young adults were associated with higher levels of uptake of the vaccine at a local level.ConclusionsThese results suggest that PCVs have an important impact on hospitalizations for all-cause pneumonia in both low- and high-income populations