Soft-mode anisotropy in the negative thermal expansion material ReO3

We use a symmetry-motivated approach to analyse neutron pair distribution function data to investigate the character of the soft phonon modes in negative thermal expansion (NTE) material ReO3. This analysis shows that its local structure is dominated by an in-phase octahedral tilting mode and that the octahedral units are far less flexible to scissoring type deformations than in the related NTE compound ScF3. The lack of flexibility in ReO3 restricts the NTE-driving phonons to a smaller region of reciprocal space, limiting the magnitude and temperature range of NTE. These results support the idea that structural flexibility is an important factor in NTE materials. Surprisingly, our results show that the local fluctuations, even at elevated temperatures, respect the symmetry and order parameter direction of the initial pressure induced phase transition in ReO3. The result indicates that the dynamic motions associated with rigid unit modes are highly anisotropic in these systems

Temporal trends of time to antiretroviral treatment initiation, interruption and modification: Examination of patients diagnosed with advanced HIV in Australia

INTRODUCTION: HIV prevention strategies are moving towards reducing plasma HIV RNA viral load in all HIV-positive persons, including those undiagnosed, treatment naïve, on or off antiretroviral therapy. A proxy population for those undiagnosed are patients that present late to care with advanced HIV. The objectives of this analysis are to examine factors associated with patients presenting with advanced HIV, and establish rates of treatment interruption and modification after initiating ART. METHODS: We deterministically linked records from the Australian HIV Observational Database to the Australian National HIV Registry to obtain information related to HIV diagnosis. Logistic regression was used to identify factors associated with advanced HIV diagnosis. We used survival methods to evaluate rates of ART initiation by diagnosis CD4 count strata and by calendar year of HIV diagnosis. Cox models were used to determine hazard of first ART treatment interruption (duration >30 days) and time to first major ART modification. RESULTS: Factors associated (p<0.05) with increased odds of advanced HIV diagnosis were sex, older age, heterosexual mode of HIV exposure, born overseas and rural-regional care setting. Earlier initiation of ART occurred at higher rates in later periods (2007-2012) in all diagnosis CD4 count groups. We found an 83% (69, 91%) reduction in the hazard of first treatment interruption comparing 2007-2012 versus 1996-2001 (p<0.001), and no difference in ART modification for patients diagnosed with advanced HIV. CONCLUSIONS: Recent HIV diagnoses are initiating therapy earlier in all diagnosis CD4 cell count groups, potentially lowering community viral load compared to earlier time periods. We found a marked reduction in the hazard of first treatment interruption, and found no difference in rates of major modification to ART by HIV presentation status in recent periods

Reverse Monte Carlo modeling of amorphous silicon

An implementation of the Reverse Monte Carlo algorithm is presented for the study of amorphous tetrahedral semiconductors. By taking into account a number of constraints that describe the tetrahedral bonding geometry along with the radial distribution function, we construct a model of amorphous silicon using the reverse monte carlo technique. Starting from a completely random configuration, we generate a model of amorphous silicon containing 500 atoms closely reproducing the experimental static structure factor and bond angle distribution and in improved agreement with electronic properties. Comparison is made to existing Reverse Monte Carlo models, and the importance of suitable constraints beside experimental data is stressed.Comment: 6 pages, 4 PostScript figure

Patterns of Mood and Personality Factors and Associations With STI/HIV-Related Drug and Sex Risk Among African American Male Inmates

Background: Research on the association between antisocial personality disorder (ASPD) with comorbid mental disorders and sexually transmitted infection (STI)/HIV risk among inmates is scant despite the high prevalence of psychopathology and of STI/HIV in this population. Methods: We used baseline data from Project DISRUPT, a cohort study conducted among incarcerated African American men (n = 207), to measure associations between ASPD and STI/HIV risk. We also conducted latent class analyses (LCAs) to identify subgroups defined by ASPD with comorbid stress, depression, and borderline personality disorder symptoms and measured associations between latent class membership and STI/HIV risk. Results: Approximately 15% had ASPD and 39% reported depression. Controlling for sociodemographics, stress, and depression, ASPD was independently associated with illicit [AOR = 3.23, 95% confidence interval (CI): 1.18–8.87] and injection drug use (AOR: 5.49, 95% CI: 1.23–24.42) but not with sexual risk. LCAs suggested that those at high risk of ASPD were likely to experience co-morbid mental disorders. ASPD comorbid with these disorders was linked to drug and sex risk. Conclusions: STI/HIV prevention for inmates should incorporate diagnosis and treatment of ASPD and comorbid disorders, and interventions to address ASPD-related factors (e.g., impulsivity) that drive STI/HIV risk

Social learning in LEADER: Exogenous, endogenous and hybrid evaluation in rural development

This paper considers the relationship between the centralised exogenous, institutions and the embedded, endogenous institutions of rural governance in Europe through an examination the evaluation procedures of the European LEADER programme. LEADER is presented in the literature as progressive in terms of innovation and stakeholder engagement. Yet while the planning and management of LEADER embraces heterogeneity and participation, programmatic evaluation is centralised and held at arms length from delivery organisations. The paper reviews previous efforts to improve evaluation in LEADER and considers alternative strategies for evaluation, contrasting LEADER practice with participatory evaluation methodologies in the wider international context. Can evaluation in itself be valuable as a mode of social learning and hence a driver for endogenous development in rural communities in Europe? The paper concludes by examining the challenges in producing a hybrid form of evaluation which accommodates endogenous and exogenous values

Determination of the structure of disordered materials by neutron scattering

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