65 research outputs found
Multiple socioeconomic deprivation and impact on survival in patients with primary glomerulonephritis
Direct Measurement of the Key e c. m.=456 keV Resonance in the Astrophysical Ne 19 (p,γ) Na 20 Reaction and Its Relevance for Explosive Binary Systems
We have performed a direct measurement of the Ne19(p,γ)Na20 reaction in inverse kinematics using a beam of radioactive Ne19. The key astrophysical resonance in the Ne19+p system has been definitely measured for the first time at Ec.m.=456-2+5 keV with an associated strength of 17-5+7 meV. The present results are in agreement with resonance strength upper limits set by previous direct measurements, as well as resonance energies inferred from precision (He3, t) charge exchange reactions. However, both the energy and strength of the 456 keV resonance disagree with a recent indirect study of the Ne19(d, n)Na20 reaction. In particular, the new Ne19(p,γ)Na20 reaction rate is found to be factors of ∼8 and ∼5 lower than the most recent evaluation over the temperature range of oxygen-neon novae and astrophysical x-ray bursts, respectively. Nevertheless, we find that the Ne19(p,γ)Na20 reaction is likely to proceed fast enough to significantly reduce the flux of F19 in nova ejecta and does not create a bottleneck in the breakout from the hot CNO cycles into the rp process
Investigation of the role of Li resonances in the halo structure of Li through the Li(p, d)Li transfer reaction
International audienceThe first measurement of the one-neutron transfer reaction 11Li(p,d)10Li performed using the IRIS facility at TRIUMF with a 5.7AMeV11Li beam interacting with a solid H2 target is reported. The 10Li residue was populated strongly as a resonance peak with energy Er=0.62 ±0.04MeV having a total width = 0.33 ±0.07MeV. The angular distribution of this resonance is characterized by neutron occupying the 1p1/2orbital. A DWBA analysis yields a spectroscopic factor of 0.67 ±0.12for p1/2 removal strength from the ground state of 11Li to the region of the peak
Area selection for diamonds using magnetotellurics : examples from southern Africa
Author Posting. © Elsevier B.V., 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Lithos 112 (2009): 83-92, doi:10.1016/j.lithos.2009.06.011.Southern Africa, particularly the Kaapvaal Craton, is one of the world’s best natural
laboratories for studying the lithospheric mantle given the wealth of xenolith and seismic data
that exist for it. The Southern African Magnetotelluric Experiment (SAMTEX) was launched
to complement these databases and provide further constraints on physical parameters and
conditions by obtaining information about electrical conductivity variations laterally and with
depth. Initially it was planned to acquire magnetotelluric data on profiles spatially coincident
with the Kaapvaal Seismic Experiment, however with the addition of seven more partners to
the original four through the course of the experiment, SAMTEX was enlarged from two to
four phases of acquisition, and extended to cover much of Botswana and Namibia. The
complete SAMTEX dataset now comprises MT data from over 675 distinct locations in an
area of over one million square kilometres, making SAMTEX the largest regional-scale MT
experiment conducted to date.
Preliminary images of electrical resistivity and electrical resistivity anisotropy at 100
km and 200 km, constructed through approximate one-dimensional methods, map resistive
regions spatially correlated with the Kaapvaal, Zimbabwe and Angola Cratons, and more
conductive regions spatially associated with the neighbouring mobile belts and the Rehoboth
Terrain. Known diamondiferous kimberlites occur primarily on the boundaries between the
resistive or isotropic regions and conductive or anisotropic regions.
Comparisons between the resistivity image maps and seismic velocities from models
constructed through surface wave and body wave tomography show spatial correlations
between high velocity regions that are resistive, and low velocity regions that are conductive.
In particular, the electrical resistivity of the sub-continental lithospheric mantle of the
Kaapvaal Craton is determined by its bulk parameters, so is controlled by a bulk matrix
property, namely temperature, and to a lesser degree by iron content and composition, and is
not controlled by contributions from interconnected conducting minor phases, such as
graphite, sulphides, iron oxides, hydrous minerals, etc. This makes quantitative correlations
between velocity and resistivity valid, and a robust regression between the two gives an
approximate relationship of Vs [m/s] = 0.045*log(resistivity [ohm.m]).We especially thank our
academic funding sponsors; the Continental Dynamics programme of the U.S. National
Science Foundation, the South African Department of Science and Technology, and Science
Foundation Ireland
Lithospheric geometry of the Wopmay orogen from a Slave craton to Bear Province magnetotelluric transect
Two‐dimensional inversions of lithospheric‐probing magnetotelluric (MT) data at a total of 20 sites acquired along an approximately east–west 300‐km‐long profile across the Wopmay orogen in the Northwest Territories, Canada, provide electrical resistivity models of the boundary between the Archean Slave craton and the adjacent Proterozoic Bear Province. An analysis of distortion effects and structural dimensionality indicates that the MT responses are primarily one‐dimensional or only weakly two‐dimensional with a depth‐independent geoelectric strike angle of N32°E, consistent with regional structural geology. The regional‐scale model, generated from the longer period responses from all of the sites along the profile, reveals significant lateral variations in the lithospheric mantle. Resistive cratonic roots are imaged to depths of ∼200 km beneath both the Slave craton and the Hottah terrane of the Bear Province. These are separated by a less resistive region beneath the Great Bear magmatic zone, which is speculatively interpreted as a consequence of a decrease in the grain size of olivine in the Wopmay mantle, caused by localized shearing, compared to its neighboring cratonic roots. Focused two‐dimensional models, from higher frequency responses at sites on specific sections of the profile, reveal the resistivity structure at crustal depths beneath the region. These suggest that the root of the Slave craton crosses beneath the Wopmay orogen, and that the Wopmay fault zone does not penetrate into the lower crust. A comparison of these results with those obtained during the Lithoprobe project farther south shows striking along strike variations in the conductivity structure associated with the Wopmay orogen
Penetration of crustal melt beyond the Kunlun Fault into northern Tibet
The weak lithosphere of the Tibetan plateau is surrounded by rigid crustal blocks1 and the transition between these regimes plays a key role in the ongoing collision between India and Eurasia. Geophysical data2,3,4,5 and magmatic evidence6,7 support the notion that partial melt exists within the anomalously hot7,8 crust of northern Tibet. The Kunlun Fault, which accommodates the plateau’s eastward extrusion, has been identified as a significant rheological boundary4 between weak, warm Tibetan crust8 and the rigid eastern Kunlun–Qaidam block. Here we present reanalyses and remodelling of existing magnetotelluric data4, using an anisotropy code9 to obtain revised resistivity models. We find unequivocal evidence for anisotropy in conductivity at the northern edge of the Tibetan plateau. We interpret this anisotropy as the signature of intrusion of melt that penetrates north from the Tibetan plateau and weakens the crust beneath the Kunlun Shan. We suggest that our identification of a melt intrusion at the northern edge of the Tibetan plateau compromises the previous identification of the Kunlun Fault as an important rheological boundary. We conclude that the crustal melt penetration probably characterizes the growth of the plateau10 to the north, as well as accommodating the north–south crustal shortening in Tibet
Fault zone conductors in Northwest Turkey inferred from audio frequency magnetotellurics
Household, community, sub-national and country-level predictors of primary cooking fuel switching in nine countries from the PURE study
Introduction. Switchingfrom polluting (e.g. wood, crop waste, coal)to clean (e.g. gas, electricity) cooking
fuels can reduce household air pollution exposures and climate-forcing emissions.While studies have
evaluated specific interventions and assessed fuel-switching in repeated cross-sectional surveys, the role
of different multilevel factors in household fuel switching, outside of interventions and across diverse
community settings, is not well understood. Methods.We examined longitudinal survey data from
24 172 households in 177 rural communities across nine countries within the Prospective Urban and
Rural Epidemiology study.We assessed household-level primary cooking fuel switching during a
median of 10 years offollow up (∼2005–2015).We used hierarchical logistic regression models to
examine the relative importance of household, community, sub-national and national-level factors
contributing to primary fuel switching. Results. One-half of study households(12 369)reported
changing their primary cookingfuels between baseline andfollow up surveys. Of these, 61% (7582)
switchedfrom polluting (wood, dung, agricultural waste, charcoal, coal, kerosene)to clean (gas,
electricity)fuels, 26% (3109)switched between different polluting fuels, 10% (1164)switched from clean
to polluting fuels and 3% (522)switched between different clean fuels
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