Stable isotopes in diatom silica

Diatom silica is a form of biogenic opal (SiO2.nH2O, Figure 1) containing oxygen, silicon, carbon and nitrogen isotopes that can be used in lacustrine and marine paleoenvironmental studies. Since diatoms bloom following a seasonal pattern defined partly by the variability of climate, nutrient supply, mixing regimes, and in high latitudes the period of ice cover, the isotope signature acquired by diatoms will be skewed toward their major growing season specific to the lake or oceanic region under consideration. The isotope ratio (e.g. 18O/16O, 30Si/28Si, 13C/12C, 15N/14N) of diatom silica are expressed on the deltascale (δ) in terms of per mille (or per mille) (‰): δ = [(Rsample/Rreference) – 1] • 1000 ‰ Where R is the particular isotope ratio (e.g. 18O/16O, 30Si/28Si), and ‘reference’ means the appropriate universally accepted reference material. The ‘δ’ for each element takes its name from the heavy isotope, thus δ18O, δ30Si, δ13C, δ15N. For diatom oxygen the reference is VSMOW (Vienna Standard Mean Ocean Water) calibrated through the quartz NBS28, for silicon it is referenced and measured alongside NBS28, for carbon the reference is VPDB (Vienna PeeDee Belemnite) calibrated against NBS19 and NBS22, and for nitrogen it is atmospheric nitrogen, commonly shortened to AIR. There are no universally accepted standard materials to analyse alongside diatoms although most laboratories use their own standard diatomites as well as NBS quartz and low %C and %N organic materials

Dielectric molding apparatus Patent

Dielectric apparatus for heating, fusing, and hardening of organic matrix to form plastic material into shaped produc

Capitalizing On Diversity: Interpersonal Congruence In Small Work Groups

We examine interpersonal congruence, the degree to which group members see others in the group as others see themselves, as a moderator of the relationship between diversity and group effectiveness. A longitudinal study of 83 work groups revealed that diversity tended to improve creative task performance in groups with high interpersonal congruence, whereas diversity undermined the performance of groups with low interpersonal congruence. This interaction effect also emerged on measures of social integration, group identification, and relationship conflict. By eliciting self-verifying appraisals, members of some groups achieved enough interpersonal congruence during their first ten minutes of interaction to benefit their group outcomes four months later. In contrast to theories of social categorization, the interpersonal congruence approach suggests that group members can achieve harmonious and effective work processes by expressing rather than suppressing the characteristics that make them unique.Managemen

Contribution of street food to dietary intake of habitual urban consumers: a cross-sectional study in Kampala city, Uganda

Background: Street food has continued to be a popular food source in the urban settings of developing countries and is proving to be a vital urban dietary source. However, its dietary contribution among urban populations is yet to be comprehensively understood. Aim: To assess how street food contributes to the dietary intake of habitual street food consumers. Methods: We conducted a community-based cross-sectional study among habitual street food consumers in Kampala city. We defined habitual intake as consumption of a serving of any street food for ≥2 days/week regardless of the food group and number of times it was consumed in a particular day. Questionnaires were used to capture quantitative data on sociodemographic characteristics, anthropometry, 24-hour diet intake and 2-month street food consumption frequency. The Nutritics® diet analysis software version 4.3 and STATA version 13.0 were used for nutrient and statistical analyses respectively. Results: Street food contributed considerably to the daily intake of fat (49.1%), sodium (38.4%) and calcium (36.5%) and least towards the daily intake of vitamin A (11.3%). The majority of consumers opted for street food at breakfast (50%) whereas lunch and snacks featured the least for overall street food inclusion (all 20%). Overall, men demonstrated more dietary intake and inclusion at meals from street food than women. Conclusions: This study indicates a significant contribution of street food for urban consumers but men derive more benefit than women in terms of nutrient intake and inclusion of street food in meals

van der Waals coefficients for positronium interactions with atoms

The random-phase approximation with exchange (RPAE) is used with a $B$-spline basis to compute dynamic dipole polarizabilities of noble-gas atoms and several other closed-shell atoms (Be, Mg, Ca, Zn, Sr, Cd, and Ba). From these, values of the van der Waals $C_6$ constants for positronium interactions with these atoms are determined and compared with existing data. Our best predictions of $C_6$ for Ps--noble-gas pairs are expected to be accurate to within 1%, and to within a few per cent for the alkaline earths. We also used accurate dynamic dipole polarizabilities from the literature to compute the $C_6$ coefficients for the alkali-metal atoms. Implications of increased $C_6$ values for Ps scattering from more polarizable atoms are discussed.Comment: 6 pages, submitted to Physical Review

Vibrational Feshbach Resonances Mediated by Nondipole Positron-Molecule Interactions

Measurements of energy-resolved positron-molecule annihilation show the existence of positron binding and vibrational Feshbach resonances. The existing theory describes this phenomenon successfully for the case of infrared-active vibrational modes which allow dipole coupling between the incident positron and the vibrational motion. Presented here are measurements of positron-molecule annihilation made using a recently developed cryogenic positron beam capable of significantly improved energy resolution. The results provide evidence of resonances associated with infrared-inactive vibrational modes, indicating that positron-molecule bound states may be populated by nondipole interactions. The anticipated ingredients for a theoretical description of such interactions are discussed.Comment: 5 pages, 2 figures, Phys. Rev. Lett. (in press

Potentials for hyper-Kahler metrics with torsion

We prove that locally any hyper-K\"ahler metric with torsion admits an HKT potential.Comment: 9 page

Characterizing the metabolic phenotype of intestinal villus blunting in Zambian children with severe acute malnutrition and persistent diarrhea

Background: Environmental enteric dysfunction (EED) is widespread throughout the tropics and in children is associated with stunting and other adverse health outcomes. One of the hallmarks of EED is villus damage. In children with severe acute malnutrition (SAM) the severity of enteropathy is greater and short term mortality is high, but the metabolic consequences of enteropathy are unknown. Here, we characterize the urinary metabolic alterations associated with villus health, classic enteropathy biomarkers and anthropometric measurements in severely malnourished children in Zambia. Methods/Principal findings: We analysed 20 hospitalised children with acute malnutrition aged 6 to 23 months in Zambia. Small intestinal biopsies were assessed histologically (n = 15), anthropometric and gut function measurements were collected and the metabolic phenotypes were characterized by 1H nuclear magnetic resonance (NMR) spectroscopy. Endoscopy could not be performed on community controls children. Growth parameters were inversely correlated with enteropathy biomarkers (p = 0.011) and parameters of villus health were inversely correlated with translocation and permeability biomarkers (p = 0.000 and p = 0.015). Shorter villus height was associated with reduced abundance of metabolites related to gut microbial metabolism, energy and muscle metabolism (p = 0.034). Villus blunting was also related to increased sucrose excretion (p = 0.013). Conclusions/Significance: Intestinal villus blunting is associated with several metabolic perturbations in hospitalized children with severe undernutrition. Such alterations include altered muscle metabolism, reinforcing the link between EED and growth faltering, and a disruption in the biochemical exchange between the gut microbiota and host. These findings extend our understanding on the downstream consequences of villus blunting and provide novel non-invasive biomarkers of enteropathy dysfunction. The major limitations of this study are the lack of comparative control group and gut microbiota characterization

Geology of Hadley Rille

The regional setting, external and internal shape, and materials of Hadley Rille near the Apollo 15 landing site are described. The petrography presented includes lithologies, regolith, talus, and outcrops. The stratigraphy exposed on the rille wall is also considered