AdS Strings with Torsion: Non-complex Heterotic Compactifications

Combining the effects of fluxes and gaugino condensation in heterotic supergravity, we use a ten-dimensional approach to find a new class of four-dimensional supersymmetric AdS compactifications on almost-Hermitian manifolds of SU(3) structure. Computation of the torsion allows a classification of the internal geometry, which for a particular combination of fluxes and condensate, is nearly Kahler. We argue that all moduli are fixed, and we show that the Kahler potential and superpotential proposed in the literature yield the correct AdS radius. In the nearly Kahler case, we are able to solve the H Bianchi using a nonstandard embedding. Finally, we point out subtleties in deriving the effective superpotential and understanding the heterotic supergravity in the presence of a gaugino condensate.Comment: 42 pages; v2. added refs, revised discussion of Bianchi for N

High-pressure annealing of a prestructured nanocrystalline precursor to obtain tetragonal and orthorhombic polymorphs of Hf3N4

Transition metal nitrides containing metal ions in high oxidation states are a significant goal for the discovery of new families of semiconducting materials. Most metal nitride compounds prepared at high temperature and high pressure from the elements have metallic bonding. However amorphous or nanocrystalline compounds can be prepared via metal-organic chemistry routes giving rise to precursors with a high nitrogen:metal ratio. Using X-ray diffraction in parallel with high pressure laser heating in the diamond anvil cell this work highlights the possibility of retaining the composition and structure of a metastable nanocrystalline precursor under high pressure-temperature conditions. Specifically, a nanocrystalline Hf3N4 with a tetragonal defect-fluorite structure can be crystallized under high-P,T conditions. Increasing the pressure and temperature of crystallization leads to the formation of a fully recoverable orthorhombic (defect cottunite-structured) polymorph. This approach identifies a novel class of pathways to the synthesis of new crystalline nitrogen-rich transition metal nitrides

Silica scale formation and effect of sodium and aluminium ions -29Si NMR study

Silica scale formation on reverse osmosis (RO) membrane surface is a significant problem for operation of high recovery RO desalination plant. In this study we report the effects of sodium ions derived from sodium chloride and aluminium ions derived from aluminium chloride on dissolved silica species obtained from commercial sodium silicate solutions. Five dissolved silica species have been positively identified in sodium silica solutions. 29 Si NMR spectroscopy has proven to be particular well suited to obtain in situ information on the connectivity of silicon atoms in the solution and the impact of sodium and aluminium ions on connectivity between monomeric silica acid groups. Such information extends the understanding of how polysilicate ion mixtures change under different chemical conditions. Implications for RO desalination and silica scale formation on the membrane surface were discussed

Identification of optimum temperatures for photosynthetic production in subtropical coastal ecosystems – implications for CO2 sequestration in a warming world

Terrestrial ecosystems are often thought to be effective sinks of anthropogenic CO2 emissions with biosphere greening considered unequivocal evidence of this process. Increasing atmospheric concentrations of CO2 along with other greenhouse gases are however, responsible for global warming. As temperature increases, the rate at which biomes sequester CO2 may decline as the optimum temperature for photosynthetic production is exceeded, thereby reducing their potential to sequester CO2. Here we present evidence from three years of direct measurements of CO2 exchanges over subtropical coastal ecosystems in eastern Australia, that the optimum temperature range for photosynthesis of 24.1 to 27.4 °C is routinely exceeded. This causes a rapid decline in photosynthetic production made worse when soil water content decreases. As climate change continues, both rising temperatures and predicted decline in rainfall will see these coastal ecosystems ability to sequester CO2 decrease further rapidly. We suggest similar research is needed urgently over other terrestrial ecosystems

Are Adolescent Risk Assessment Tools Sensitive to Change? A Framework and Examination of the SAVRY and the YLS/CMI

Although many adolescent risk assessment tools include an emphasis on dynamic factors, little research has examined the extent to which these tools are capable of measuring change. In this article, we outline a framework to evaluate a tool’s capacity to measure change. This framework includes: (1) measurement error and reliable change, and (2) sensitivity (i.e., internal, external, and relative sensitivity). We then used this framework to evaluate the Structured Assessment of Violence Risk in Youth (SAVRY) and Youth Level of Service/Case Management Inventory (YLS/CMI). Research assistants conducted 509 risk assessments with 146 adolescents on probation (101 male, 45 female), who were assessed every 3 months over a 1-year period. Internal sensitivity was partially supported, as a modest proportion of youth showed changes over time. External sensitivity (i.e., the association between change scores and reoffending) was also partially supported. In particular, 22% of the associations between change scores and any and violent reoffending were significant at a 6-month follow-up. However, only one change score (i.e., Peer Associations) remained significant after the Bonferroni correction was applied. Finally, relative sensitivity was not supported, as the SAVRY and YLS/CMI was not more dynamic than the Psychopathy Checklist: Youth Version (PCL:YV). Specifically, the 1-year rank-order stability coefficients for the SAVRY, YLS/CMI, and PCL:YV Total Scores were .78, .75, and .76, respectively. Although the SAVRY and YLS/CMI hold promise, further efforts may help to enhance sensitivity to short-term changes in risk

Ranavirus Ecology and Evolution: From Epidemiology to Extinction

Ranaviruses have been identified in wild and captive populations of ectothermic vertebrates around the world. Ranavirus epidemics can result in a range of effects on their host populations, from apparently benign infections to mass mortality and local extirpation. In this chapter, we review the current status of ranavirus epidemiology and ecology in amphibians, fish, and reptiles. Ranavirus epidemics in amphibians and fish usually have a rapid onset in the mid-to-late summer while outbreaks in reptiles occur irregularly. Susceptibility to ranavirus differs among host species, and may be influenced by the type of ranavirus and natural or anthropogenic stressors. Ranaviruses can be transmitted within and between host species via several routes, but there is a need for transmission estimates in natural environments. Generally, ranaviruses are locally adapted to their host populations, but movement of infected hosts over long distances can disrupt these associations. There is evidence of increased virulence of ranaviruses in captive fish and amphibian populations raised for production. Given their broad host ranges, potential for high virulence, multiple routes of transmission, and frequent movement of amphibians, fish and reptiles in global trade, it appears that some ranaviruses have the potential to significantly impact host populations and even cause extinctions in the wild

Does Reassessment of Risk Improve Predictions? A Framework and Examination of the SAVRY and YLS/CMI

Although experts recommend regularly reassessing adolescents\u27 risk for violence, it is unclear whether reassessment improves predictions. Thus, in this prospective study, we tested three hypotheses as to why reassessment might improve predictions, namely the shelf-life, dynamic change, and familiarity hypotheses. Research assistants (RAs) rated youth on the Structured Assessment of Violence Risk in Youth (SAVRY) and the Youth Level of Service/Case Management Inventory (YLS/CMI) every three months over a one-year period, conducting 624 risk assessments with 156 youth on probation. We then examined charges for violence and any offence over a two-year follow-up period, and youths\u27 self-reports of reoffending. Contrary to the shelf-life hypothesis, predictions did not decline or expire over time. Instead, time-dependent area under the curve scores remained consistent across the follow-up period. Contrary to the dynamic change hypothesis, changes in youth\u27s risk total scores, compared to what is average for that youth, did not predict changes in reoffending. Finally, contrary to the familiarity hypothesis, reassessments were no more predictive than initial assessments, despite RAs\u27 increased familiarity with youth. Before drawing conclusions, researchers should evaluate the extent to which youth receiving the usual probation services show meaningful short-term changes in risk and if so, whether risk assessment tools are sensitive to these changes

Changes in J-SOAP-II and SAVRY Scores Over the Course of Residential, Cognitive-Behavioral Treatment for Adolescent Sexual Offending

Although the Juvenile Sex Offender Assessment Protocol-II (J-SOAP-II) and the Structured Assessment of Violence Risk in Youth (SAVRY) include an emphasis on dynamic, or modifiable factors, there has been little research on dynamic changes on these tools. To help address this gap, we compared admission and discharge scores of 163 adolescents who attended a residential, cognitive-behavioral treatment program for sexual offending. Based on reliable change indices, one-half of youth showed a reliable decrease on the J-SOAP-II Dynamic Risk Total Score and one-third of youth showed a reliable decrease on the SAVRY Dynamic Risk Total Score. Contrary to expectations, decreases in risk factors and increases in protective factors did not predict reduced sexual, violent nonsexual, or any reoffending. In addition, no associations were found between scores on the Psychopathy Checklist: Youth Version and levels of change. Overall, the J-SOAP-II and the SAVRY hold promise in measuring change, but further research is needed

Changes in J-SOAP-II and SAVRY Scores Over the Course of Residential, Cognitive-Behavioral Treatment for Adolescent Sexual Offending

Although the Juvenile Sex Offender Assessment Protocol–II (J-SOAP-II) and the Structured Assessment of Violence Risk in Youth (SAVRY) include an emphasis on dynamic, or modifiable factors, there has been little research on dynamic changes on these tools. To help address this gap, we compared admission and discharge scores of 163 adolescents who attended a residential, cognitive-behavioral treatment program for sexual offending. Based on reliable change indices, one half of youth showed a reliable decrease on the J-SOAP-II Dynamic Risk Total Score and one third of youth showed a reliable decrease on the SAVRY Dynamic Risk Total Score. Contrary to expectations, decreases in risk factors and increases in protective factors did not predict reduced sexual, violent nonsexual, or any reoffending. In addition, no associations were found between scores on the Psychopathy Checklist:Youth Version and levels of change. Overall, the J-SOAP-II and the SAVRY hold promise in measuring change, but further research is needed