Widespread tephra dispersal and ignimbrite emplacement from a subglacial volcano (Torfajökull, Iceland)

The tephra dispersal mechanisms of rhyolitic glaciovolcanic eruptions are little known, but can be investigated through the correlation of eruptive products across multiple depositional settings. Using geochemistry and geochronology, we correlate a regionally important Pleistocene tephra horizon—the rhyolitic component of North Atlantic Ash Zone II (II-RHY-1)—and the Thórsmörk Ignimbrite with rhyolitic tuyas at Torfajökull volcano, Iceland. The eruption breached an ice mass >400 m thick, leading to the widespread dispersal of II-RHY-1 across the North Atlantic and the Greenland ice sheet. Locally, pyroclastic density currents traveled across the ice surface, depositing the variably welded Thórsmörk Ignimbrite beyond the ice margin and ~30 km from source. The widely dispersed products of this eruption represent a valuable isochronous tie line between terrestrial, marine, and ice-core paleoenvironmental records. Using the tephra horizon, estimates of ice thickness and extent derived from the eruption deposits can be directly linked to the regional climate archive, which records the eruption at the onset of Greenland Stadial 15.2

QSOs Associated with Messier 82

The starburst / AGN galaxy M82 was studied by Dahlem, Weaver and Heckman using X-ray data from ROSAT and ASCA, as part of their X-ray survey of edge-on starburst galaxies. They found seventeen unresolved hard-X-ray sources around M82, in addition to its strong nuclear source, and other X-rays within the main body of M82. We have measured optical point sources at these positions, and have obtained redshifts of six candidates at the Keck I 10-m telescope, using the low-resolution imaging spectrograph (LRIS). All six are highly compact optical and X-ray objects with redshifts ranging from 0.111 to 1.086. They all show emission lines. The three with the highest redshifts are clearly QSOs. The others with lower redshifts may either be QSOs or compact emission-line galaxies. In addition to these six there are nine QSOs lying very close to M82 which were discovered many years ago. There is no difference between optical spectra of these latter QSOs, only two of which are known to be X-ray sources, and the X-ray emitting QSOs. The redshifts of all fifteen range between 0.111 and 2.05. The large number of QSOs and their apparent association with ejected matter from M82 suggest that they are physically associated with the galaxy, and have large intrinsic redshift components. If this is correct, the absolute magnitudes lie in the range -8 < M_v < -10. Also we speculate that the luminous variable X-ray source which has been detected by Chandra in the main body of M82 some 9 arcseconds from the center is another QSO in the process of ejection from the nucleus, and propose some observational tests of this hypothesis.Comment: 16 pages aastex, 3 eps figures, accepted for publication on Ap

Soil-transmitted helminth infections and nutritional indices among Filipino schoolchildren

BACKGROUND: Soil-transmitted helminth (STH) infections are still prevalent among schoolchildren in the Philippines. We evaluated the risk factors associated with STH and the relationship between STH and nutritional indices among schoolchildren aged 9-10 years in Laguna province, the Philippines. METHODS: We used the baseline data from 40 schools enrolled in a randomised controlled trial of the Magic Glasses Philippines health education package. Data on demographic and socio-economic variables, and STH related knowledge, attitudes and practices, were obtained through a questionnaire. Stool samples were collected and assessed for STH egg presence using the Kato-Katz technique. Haemoglobin levels and height and weight of study participants were also determined. The generalized estimating equations approach was used to construct logistic regression models to assess STH-associated risk factors, and the association between any STH infection and anaemia, child stunting, wasting and being underweight. The trial is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12616000508471). FINDINGS: Among 1,689 schoolchildren, the prevalence of any STH was 23%. The prevalence of anaemia, stunting, being underweight and wasting was 13%, 20.2%, 19% and 9.5%, respectively. Age, socio-economic status, rural/urban classification of schools and knowledge of STH were significant risk factors for acquiring a STH infection. Moreover, infections with any STH were significantly associated with stunting (P = <0.001) and being underweight (P = <0.003), but not wasting (P = 0.375) or anaemia (P = 0.462) after controlling for confounding covariates. CONCLUSION: The study findings emphasise the need for sustainable deworming in tandem with other measures such as the provision of health education, improvements in sanitation and hygiene, and nutritional programs in order to control STH infections and improve morbidity outcomes in schoolchildren. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry (ACTRN12616000508471)

The Surroundings of Disturbed, Active Galaxies

The brightest apparent magnitude examples of ultra luminous infrared galaxies (ULIRG's) are studied here in X-ray, optical, infrared and radio wavelengths. It is is found that they have associated material reaching out to apparent diameters of the order of a degree on the sky. Gas, dust, X-ray material and quasars appear to be ejected from the active nuclei with all objects nearer than their redshift distances.Comment: 14 pages, Figs. 1-28 jpg and gif file

Prevalent vertebral fractures among children initiating glucocorticoid therapy for the treatment of rheumatic disorders

Objective. Vertebral fractures are an under-recognized problem in children with inflammatory disorders. We studied spine health among 134 children (87 girls) with rheumatic conditions (median age 10 years) within 30 days of initiating glucocorticoid therapy. Methods. Children were categorized as follows: juvenile dermatomyositis (n = 30), juvenile idiopathic arthritis (n = 28), systemic lupus erythematosus and related conditions (n = 26), systemic arthritis (n = 22), systemic vasculitis (n = 16), and other conditions (n = 12). Thoracolumbar spine radiograph and dual x-ray absorptiometry for lumbar spine (L-spine) areal bone mineral density (BMD) were performed within 30 days of glucocorticoid initiation. Genant semiquantitative grading was used for vertebral morphometry. Second metacarpal morphometry was carried out on a hand radiograph. Clinical factors including disease and physical activity, calcium and vitamin D intake, cumulative glucocorticoid dose, underlying diagnosis, L-spine BMD Z score, and back pain were analyzed for association with vertebral fracture. Results. Thirteen vertebral fractures were noted in 9 children (7%). Of these, 6 patients had a single vertebral fracture and 3 had 2-3 fractures. Fractures were clustered in the mid-thoracic region (69%). Three vertebral fractures (23%) were moderate (grade 2); the others were mild (grade 1). For the entire cohort, mean ± SD L-spine BMD Z score was significantly different from zero (-0.55 ± 1.2, P \u3c 0.001) despite a mean height Z score that was similar to the healthy average (0.02 ± 1.0, P = 0.825). Back pain was highly associated with increased odds for fracture (odds ratio 10.6 [95% confidence interval 2.1-53.8], P = 0.004). Conclusion. In pediatric rheumatic conditions, vertebral fractures can be present prior to prolonged glucocorticoid exposure. © 2010, American College of Rheumatology

The Importance of pH in Regulating the Function of the Fasciola hepatica Cathepsin L1 Cysteine Protease

The helminth parasite Fasciola hepatica secretes cathepsin L cysteine proteases to invade its host, migrate through tissues and digest haemoglobin, its main source of amino acids. Here we investigated the importance of pH in regulating the activity and functions of the major cathepsin L protease FheCL1. The slightly acidic pH of the parasite gut facilitates the auto-catalytic activation of FheCL1 from its inactive proFheCL1 zymogen; this process was ∼40-fold faster at pH 4.5 than at pH 7.0. Active mature FheCL1 is very stable at acidic and neutral conditions (the enzyme retained ∼45% activity when incubated at 37°C and pH 4.5 for 10 days) and displayed a broad pH range for activity peptide substrates and the protein ovalbumin, peaking between pH 5.5 and pH 7.0. This pH profile likely reflects the need for FheCL1 to function both in the parasite gut and in the host tissues. FheCL1, however, could not cleave its natural substrate Hb in the pH range pH 5.5 and pH 7.0; digestion occurred only at pH≤4.5, which coincided with pH-induced dissociation of the Hb tetramer. Our studies indicate that the acidic pH of the parasite relaxes the Hb structure, making it susceptible to proteolysis by FheCL1. This process is enhanced by glutathione (GSH), the main reducing agent contained in red blood cells. Using mass spectrometry, we show that FheCL1 can degrade Hb to small peptides, predominantly of 4–14 residues, but cannot release free amino acids. Therefore, we suggest that Hb degradation is not completed in the gut lumen but that the resulting peptides are absorbed by the gut epithelial cells for further processing by intracellular di- and amino-peptidases to free amino acids that are distributed through the parasite tissue for protein anabolism

Reducing Calorie Intake May Not Help You Lose Body Weight

Background Previously a meta-analysis found that multi-vitamin/mineral supplementation reduced mild psychiatric symptoms. To establish mechanisms, and to pin-point the individuals most likely to benefit, the role of various polymorphisms were examined. Supplementation was found to influence mild-psychiatric symptoms depending on the form of particular genes: genes that are risk factors for psychiatric disease and influence mechanisms by which drugs act. Methods In a double-blind trial young healthy males rated psychiatric symptoms, before and after taking vitamin/mineral supplements for three months, and the response was related to single nucleotide polymorphisms associated with catecholamines and serotonin. Outcomes With rs1800497 (Taq1A; dopamine D2 receptor), those with the CT allele benefitted from a vitamin/mineral supplement. Similarly with rs1800955 (DRD4 – dopamine D4 receptor), the mood of those with the CC allele benefitted selectively. With rs6296 (HTR1B) only those with the GC alleles responded, and with rs6311 (HTR2A) supplementation produced a beneficial response in those with the GG allele. With rs1050565 (5HTT gene - Human Serotonin Transporter gene) supplementation increased the mental health of those with the AA allele. Interpretation In a situation where a substantial proportion of patients do not benefit from drug therapy, and there is an element of trial and error when prescribing, it was proposed that future work should consider distinguishing patients depending on various polymorphisms and micro-nutrient status. In those with particular alleles, we should consider if drug administration and vitamin / mineral status interact synergistically to influence the therapeutic outcom

"If only I had taken the other road...": Regret, risk and reinforced learning in informed route-choice

This paper presents a study of the effect of regret on route choice behavior when both descriptional information and experiential feedback on choice outcomes are provided. The relevance of Regret Theory in travel behavior has been well demonstrated in non-repeated choice environments involving decisions on the basis of descriptional information. The relation between regret and reinforced learning through experiential feedbacks is less understood. Using data obtained from a simple route-choice experiment involving different levels of travel time variability, discrete-choice models accounting for regret aversion effects are estimated. The results suggest that regret aversion is more evident when descriptional information is provided ex-ante compared to a pure learning from experience condition. Yet, the source of regret is related more strongly to experiential feedbacks rather than to the descriptional information itself. Payoff variability is negatively associated with regret. Regret aversion is more observable in choice situations that reveal risk-seeking, and less in the case of risk-aversion. These results are important for predicting the possible behavioral impacts of emerging information and communication technologies and intelligent transportation systems on travelers' behavior. © 2012 Springer Science+Business Media, LLC