Inelastic fingerprints of hydrogen contamination in atomic gold wire systems

We present series of first-principles calculations for both pure and hydrogen contaminated gold wire systems in order to investigate how such impurities can be detected. We show how a single H atom or a single H2 molecule in an atomic gold wire will affect forces and Au-Au atom distances under elongation. We further determine the corresponding evolution of the low-bias conductance as well as the inelastic contributions from vibrations. Our results indicate that the conductance of gold wires is only slightly reduced from the conductance quantum G0=2e^2/h by the presence of a single hydrogen impurity, hence making it difficult to use the conductance itself to distinguish between various configurations. On the other hand, our calculations of the inelastic signals predict significant differences between pure and hydrogen contaminated wires, and, importantly, between atomic and molecular forms of the impurity. A detailed characterization of gold wires with a hydrogen impurity should therefore be possible from the strain dependence of the inelastic signals in the conductance.Comment: 5 pages, 3 figures, Contribution to ICN+T2006, Basel, Switzerland, July-August 200

The Use of Classroom Walk-Through Observations as a Strategy for Improving Teaching and Learning: Teacher Perspective

The purpose of this study was to investigate the use of classroom walk-through observations and their effect on Communication Arts and Mathematics Missouri Assessment Program (MAP) scores, summer school placement, discipline referrals, and retention. This study was conducted in three Midwestern Middle Schools. This study focused on classroom walk-through observations. If the principal increased the number of classroom walk-through observations, would it have an impact on Communication Arts and Mathematics MAP scores, summer school placement, discipline referrals and retention? This study will attempt to determine if classroom walk-through observations had an impact on Communication Arts MAP scores, Mathematics MAP scores, Summer School placement, discipline referrals and retention. The data from this study was from the school years 2005-2006, 2006-2007, and 2007-2008. Classroom walk-through observations began in the ABC School District in the year 2006. The ABC School District used a walk-through form that is very detailed. The findings showed that yes, there was a decrease in discipline referrals, summer school placement, and retention, and there was an increase in student achievement in regards to Communication Art MAP test scores and Mathematics MAP test scores. It cannot be concluded that the classroom walk-through observations are the reason for the increase in student achievement. When educators look at the changes that education has gone through over the last twenty years, the focus is on the growth of the students and how the changes have impacted their student achievement. Classroom walk-through observations are one of the many changes that have occurred in education. Can brief classroom observations regarding best practices have a positive impact on student achievement and school climate? There is not one single thing that is a fix for the problems that are occurring in the educational realm, but by examining different key points, educators can decipher which programs are working and which ones are not working. A possibility exists that the statistical data cannot provide the desired information

“It will not be easy to accept”: Parents conflicting attitudes towards pre-exposure prophylaxis for HIV prevention amongst adolescent girls and young women in Zimbabwe

Background: Pre-exposure prophylaxis, or PrEP, is a pill that has been hailed as a ‘game changer’ for HIV prevention, based on the belief it provides adolescent girls and young women (AGYW) with a level of user-control. However, engagement with PrEP is often dependent on societal factors, such as social attitudes towards gender, sexuality, and PrEP. As parents' communication on sexual and reproductive health issues with AGYW are central to HIV prevention, it is critical to explore how parents talk and think about PrEP. Objective: To examine parental attitudes towards PrEP for HIV prevention amongst adolescent girls and young women in eastern Zimbabwe. Method: A qualitative interview study with 14 parents from two districts in Manicaland, eastern Zimbabwe. Interviews were transcribed, translated, and subjected to thematic network analysis. The concept of ‘attitudes’ steered the analytical work. Results: Parents' attitudes towards PrEP are conflictual, multi-layered, and contingent on the context in which they reflect and talk about PrEP. While parents aspired to be supportive of innovative HIV prevention methods and wanted to see girl-children protected from HIV, they struggled to reconcile this positive and accepting attitude towards PrEP with traditional ‘good girl’ notions, which stigmatize pre-marital sex. Although a few parents articulated an acceptance of PrEP use amongst their daughters, for many this was simply not possible. Many parents thus co-produce public gender orders that prevent adolescent girls and young women from engaging with PrEP. Conclusions: While parents’ conflicting attitudes towards PrEP may provide spaces and opportunities for change, harmful gender norms and negative attitudes towards PrEP must be addressed at a community and cultural level. Only then can parents and their children have productive conversations about sexual health

Changes in posterior scleral collagen microstructure in canine eyes with an ADAMTS10 mutation

Purpose: We aimed to characterize alterations in the posterior scleral collagen microstructure before detectable disease onset in a canine model of open-angle glaucoma caused by an ADAMTS10 mutation. Methods: Collagen orientation, anisotropy degree (proportion of preferentially aligned collagen), and relative density were measured at 0.4 mm spatial resolution using synchrotron wide-angle X-ray scattering. For statistical evaluation of structure parameters, regional averages of the peripapillary and mid-posterior sclera were compared between ADAMTS10 mutant (affected) dogs (n = 3) and age-matched (carrier) controls (n = 3). Results: No marked differences in the general pattern of preferential collagen fibril orientation were noted between the control and affected dogs. The peripapillary sclera of all specimens featured strongly aligned circumferential collagen ringing the optic nerve head. Collagen anisotropy was significantly reduced in the mid-posterior sclera of the affected dogs (carrier: 0.27±0.11; affected: 0.24±0.10; p = 0.032) but was not statistically significantly different in the peripapillary sclera (carrier: 0.46±0.15; affected: 0.45±0.17; p = 0.68). Collagen density was statistically significantly reduced in the affected dogs for the mid-posterior sclera (carrier: 28.1±9.14; affected: 18.3±5.12; p<0.0001) and the peripapillary sclera (carrier: 34.6±9.34; affected: 21.1±6.97; p = 0.0002). Conclusions: Significant alterations in the posterior scleral collagen microstructure are present before the onset of clinical glaucoma in ADAMTS10 mutant dogs. A reduction in fibrous collagen density is likely an important contributory factor in the previously reported mechanical weakening of the sclera in this model. Baseline scleral abnormalities have the potential to interact with intraocular pressure (IOP) elevations in determining the course of glaucoma progression in animal models of the disease, and potentially in human glaucoma

Structural studies reveal the enantiospecific recognition of a DNA G-quadruplex by a ruthenium polypyridyl complex

Using X-ray crystallography, we show an enantiospecificity in DNA G-quadruplex binding, using the complexes Λ/∆-[Ru(TAP)2(dppz-11-CN)]2+ (TAP=1,4,5,8-tetraazaphenanthrene) containing the dppz (dipyridophenazine) ligand, paralleling the specificity of the complexes with duplex DNA. The Λ complex crystallises with the normally parallel stranded d(TAGGGTTA) tetraplex to give the first such antiparallel strand assembly in which syn-guanosine is adjacent to the complex at the 5’ end of the quadruplex core. SRCD measurements confirm that the same conformational switch occurs in solution. The Δ enantiomer, by contrast, is present in the structure but stacked at the ends of the assembly. In addition, we report the structure of Λ-[Ru(phen)2(11-CN-dppz)]2+ bound to d(TCGGCGCCGA), a duplex forming sequence, and use both structural models to aid in the elucidation of the motif-specific luminescence response of the isostructural phen analogue enantiomers

Antiproton Production in p+Ap+A Collisions at AGS Energies

Inclusive and semi-inclusive measurements are presented for antiproton ($\bar{p}$) production in proton-nucleus collisions at the AGS. The inclusive yields per event increase strongly with increasing beam energy and decrease slightly with increasing target mass. The $\bar{p}$ yield in 17.5 GeV/c p+Au collisions decreases with grey track multiplicity, $N_g$, for $N_g>0$, consistent with annihilation within the target nucleus. The relationship between $N_g$ and the number of scatterings of the proton in the nucleus is used to estimate the $\bar{p}$ annihilation cross section in the nuclear medium. The resulting cross section is at least a factor of five smaller than the free $\bar{p}-p$ annihilation cross section when assuming a small or negligible formation time. Only with a long formation time can the data be described with the free $\bar{p}-p$ annihilation cross section.Comment: 8 pages, 6 figure

Presymptomatic risk assessment for chronic non-communicable diseases

The prevalence of common chronic non-communicable diseases (CNCDs) far overshadows the prevalence of both monogenic and infectious diseases combined. All CNCDs, also called complex genetic diseases, have a heritable genetic component that can be used for pre-symptomatic risk assessment. Common single nucleotide polymorphisms (SNPs) that tag risk haplotypes across the genome currently account for a non-trivial portion of the germ-line genetic risk and we will likely continue to identify the remaining missing heritability in the form of rare variants, copy number variants and epigenetic modifications. Here, we describe a novel measure for calculating the lifetime risk of a disease, called the genetic composite index (GCI), and demonstrate its predictive value as a clinical classifier. The GCI only considers summary statistics of the effects of genetic variation and hence does not require the results of large-scale studies simultaneously assessing multiple risk factors. Combining GCI scores with environmental risk information provides an additional tool for clinical decision-making. The GCI can be populated with heritable risk information of any type, and thus represents a framework for CNCD pre-symptomatic risk assessment that can be populated as additional risk information is identified through next-generation technologies.Comment: Plos ONE paper. Previous version was withdrawn to be updated by the journal's pdf versio