U-series Disequilibria in Guatemalan Lavas, Crustal Contamination, and Implications for Magma Genesis Along the Central American Subduction Zone

New U-series results indicate that Guatemalan volcanic rocks display both 238U and 230Th excesses. 230Th excess is restricted to volcanoes in central Guatemala, both along and behind the front. 230Th excess correlates with a number of incompatible element ratios, such as Th/Nb and Ba/Th. It also shows a negative correlation with MgO. Guatemalan volcanic rocks have (230Th/232Th) ratios that overlap those of Costa Rican volcanics and are therefore considerably lower than the unusually high ratios characterizing volcanic rocks from Nicaragua. Along-arc variations in (230Th/232Th) therefore mirror those of a number of diagnostic geochemical parameters, such as Ba/La, which are symmetrical about a peak in west central Nicaragua. The one siliceous lava analyzed, from the Cerro Quemado dome complex, has a recognizable crustal imprint, distinguished, for instance, by high Th/Nb and low Ba/Th. In mafic samples, 238U excess is attributed to addition of a U-enriched fluid component from the subducting Cocos plate. Our preferred explanation for 230Th excess in Guatemalan mafic samples, on the other hand, is crustal contamination, consistent with the relatively high Th/Nb and low Ba/Th ratios in these samples. We suspect, however, that crustal contamination only exerts a sizable control over the U-series disequilibrium of mafic magmas in Guatemala, and not elsewhere along the Central American volcanic front. This agrees with previously published trace element and isotopic evidence that throughout Central America, with the exception of Guatemala, mafic magmas are largely uncontaminated by crustal material.The work was supported by NSF grant OCE-0405666

The purpose of mess in action research: building rigour though a messy turn

Mess and rigour might appear to be strange bedfellows. This paper argues that the purpose of mess is to facilitate a turn towards new constructions of knowing that lead to transformation in practice (an action turn). Engaging in action research - research that can disturb both individual and communally held notions of knowledge for practice - will be messy. Investigations into the 'messy area', the interface between the known and the nearly known, between knowledge in use and tacit knowledge as yet to be useful, reveal the 'messy area' as a vital element for seeing, disrupting, analysing, learning, knowing and changing. It is the place where long-held views shaped by professional knowledge, practical judgement, experience and intuition are seen through other lenses. It is here that reframing takes place and new knowing, which has both theoretical and practical significance, arises: a 'messy turn' takes place

Treatment preference amongst people with cystic fibrosis: the importance of reducing treatment burden

BACKGROUND: There is a growing consensus that the perspective of the patient should be considered in the evaluation of novel interventions. RESEARCH QUESTION: What treatment outcomes matter to people with cystic fibrosis (CF), and what trade-offs would they make to realise these outcomes? STUDY DESIGN AND METHODS: Adults attending a specialist CF centre were invited to complete an online discrete choice experiment (DCE). The DCE required participants to evaluate hypothetical CF treatment profiles, defined by impact on lung function, pulmonary exacerbations, abdominal symptoms, life expectancy, quality of life, inhaled medicines usage, and physiotherapy requirement. Choice data were analysed using multinomial logit and latent class models. RESULTS: 103 people with CF completed the survey (median age 35 years (range 18-76); 52% female; mean ppFEV1 69% (SD 22)). On average, an improvement in life expectancy by 10 years or more had the greatest impact on treatment preference, followed by a 15% increase in lung function. However, it was shown that people would trade substantial reductions in these key outcomes to reduce treatment time or burden. Preference profiles were not uniform across the sample: three distinct subgroups were identified, each placing markedly different importance on the relative importance of both life expectancy and lung function compared to other attributes. INTERPRETATION: The relative importance of treatment burden to people with CF, compared to life expectancy and lung function suggests it should be routinely captured in clinical trials as an important secondary outcome measure. When considering the patient perspective, it is important that decision makers recognise that the values of people with CF are not homogenous

Exploring the nature of perceived treatment burden: a study to compare treatment burden measures in adults with cystic fibrosis [version 1; peer review: 2 approved]

Background: Despite the importance of reducing treatment burden for people with cystic fibrosis (CF), it has not been fully understood as a concept. This study aims to quantify the treatment burden perceived by CF adults and explore the association between different validated treatment burden measures. Methods: This is a cross-sectional observational study of CF adults attending a single large UK adult center. Participants completed an online survey that contained three different treatment burden scales; CF Questionnaire-Revised (CFQ-R) subscale, CF Quality of Life (CFQoL) subscale, and the generic multimorbidity treatment burden questionnaire (MTBQ). Results: Among 101 participants, the median reported treatment burden by the CFQ-R subscale was 55.5 (IQR 33.3 – 66.6), the CFQoL subscale was 66.6 (IQR 46.6 – 86.6), and the MTBQ reversed global score was 84.6 (IQR 73.1 – 92.3). No correlation was found between respondents’ demographic or clinical variables and treatment burden measured via any of the three measures. All treatment burden measures showed correlations against each other. More treatments were associated with high treatment burden as measured by the CFQ-R, CFQoL subscales, and the MTBQ. However, longer treatment time and more complex treatment plans were correlated with high treatment burden as measured by the CFQ-R and CFQoL subscales, but not with the MTBQ. Conclusions: Treatment burden is a substantial issue in CF. Currently, the only available way to evaluate it is with the CF-specific quality of life measure treatment burden subscales (CFQ-R and CFQoL); both indicated that treatment burden increases with more treatments, longer treatment time, and more complex treatments

Transient Pulses from Exploding Primordial Black Holes as a Signature of an Extra Dimension

An evaporating black hole in the presence of an extra spatial dimension would undergo an explosive phase of evaporation. We show that such an event, involving a primordial black hole, can produce a detectable, distinguishable electromagnetic pulse, signaling the existence of an extra dimension of size $L\sim10^{-18}-10^{-20}$ m. We derive a generic relationship between the Lorentz factor of a pulse-producing "fireball" and the TeV energy scale. For an ordinary toroidally compactified extra dimension, transient radio-pulse searches probe the electroweak energy scale ($\sim$0.1 TeV), enabling comparison with the Large Hadron Collider.Comment: 11 pages, 1 figure; references added; typos corrected; clarifying remarks added near the end of section

Microtermolides A and B from Termite-Associated Streptomyces sp. and Structural Revision of Vinylamycin

Microtermolides A (1) and B (2) were isolated from a Streptomyces sp. strain associated with fungus-growing termites. The structures of 1 and 2 were determined by 1D- and 2D-NMR spectroscopy and high-resolution mass spectrometry. Structural elucidation of 1 led to the re-examination of the structure originally proposed for vinylamycin (3). Based on a comparison of predicted and experimental $^1$H and $^{13}$C NMR chemical shifts, we propose that vinylamycin’s structure be revised from 3 to 4

Search for the glueball candidates f0(1500) and fJ(1710) in gamma gamma collisions

Data taken with the ALEPH detector at LEP1 have been used to search for gamma gamma production of the glueball candidates f0(1500) and fJ(1710) via their decay to pi+pi-. No signal is observed and upper limits to the product of gamma gamma width and pi+pi- branching ratio of the f0(1500) and the fJ(1710) have been measured to be Gamma_(gamma gamma -> f0(1500)). BR(f0(1500)->pi+pi-) < 0.31 keV and Gamma_(gamma gamma -> fJ(1710)). BR(fJ(1710)->pi+pi-) < 0.55 keV at 95% confidence level.Comment: 10 pages, 3 figure

Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV

A search for pair-production of supersymmetric particles under the assumption that R-parity is violated via a dominant LQDbar coupling has been performed using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV. The observed candidate events in the data are in agreement with the Standard Model expectation. This result is translated into lower limits on the masses of charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81 GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the 95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure

Sodium bicarbonate supplementation improves severe-intensity intermittent exercise under moderate acute hypoxic conditions

Acute moderate hypoxic exposure can substantially impair exercise performance, which occurs with a concurrent exacerbated rise in hydrogen cation (H+) production. The purpose of this study was therefore, to alleviate this acidic stress through sodium bicarbonate (NaHCO3) supplementation and determine the corresponding effects on severe intensity intermittent exercise performance. Eleven recreationally active individuals participated in this randomised, double-blind, crossover study performed under acute normobaric hypoxic conditions (FiO2% = 14.5%). Pre-experimental trials involved the determination of time to attain peak bicarbonate anion concentrations ([HCO3-]) following NaHCO3 ingestion. The intermittent exercise tests involved repeated 60 s work in their severe intensity domain and 30 s recovery at 20 W to exhaustion. Participants ingested either 0.3 g·kg bm-1 of NaHCO3 or a matched placebo of 0.21 g·kg bm-1 of sodium chloride prior to exercise. Exercise tolerance (+110.9 ± 100.6 s; 95% CI: 43.3 to 178 s; g = 1.0) and work performed in the severe intensity domain (+5.8 ± 6.6 kJ; 95% CI: 1.3 to 9.9 kJ; g = 0.8) were enhanced with NaHCO3 supplementation. Furthermore, a larger post-exercise blood lactate concentration was reported in the experimental group (+4 ± 2.4 mmol·l-1; 95% CI: 2.2 to 5.9; g = 1.8), while blood [HCO3-] and pH remained elevated in the NaHCO3 condition throughout experimentation. In conclusion, this study reported a positive effect of NaHCO3 under acute moderate hypoxic conditions during intermittent exercise and therefore, may offer an ergogenic strategy to mitigate hypoxic induced declines in exercise performance