5,492 research outputs found
The Dark Matter Telescope
Weak gravitational lensing enables direct reconstruction of dark matter maps
over cosmologically significant volumes. This research is currently
telescope-limited. The Dark Matter Telescope (DMT) is a proposed 8.4 m
telescope with a 3 degree field of view, with an etendue of 260 , ten times greater than any other current or planned telescope. With
its large etendue and dedicated observational mode, the DMT fills a nearly
unexplored region of parameter space and enables projects that would take
decades on current facilities. The DMT will be able to reach 10-sigma limiting
magnitudes of 27-28 magnitude in the wavelength range .3 - 1 um over a 7 square
degree field in 3 nights of dark time. Here we review its unique weak lensing
cosmology capabilities and the design that enables those capabilities.Comment: in-press version with additions; to appear in proceedings of the Dark
Matter 2000 conference (Santa Monica, February 2000) to be published by
Springe
Convergence of the waste and water sectors: risks, opportunities and future trends – discussion paper
The aim of this discussion paper is to bring to light the increasing convergence of the water and waste sectors and the associated risks, benefits, and future trends already on the horizon. Current examples of convergence in managing coal seam gas (CSG), food waste, fats, oils and grease (FOG) and biosolids, provide insights into not only the risks to public and environmental health of waste streams that cross sectoral boundaries but also potential opportunities for the water and waste sectors to seize as business opportunities. What is clear is that convergence between these sectors is already happening and in some cases there are adverse environmental consequences and associated health impacts. A key message from this research is the need to take an integrated and coordinated approach to planning and regulating the convergence of the water and waste sectors. Key recommendations to manage the risks associated with cross sector convergence of the water and waste sectors include facilitating: (1) increased engagement between regulators of each sector, (2) greater communication across sectors (3) a co-ordinated approach and plan to managing waste streams, (4) the development of monitoring and evaluation frameworks that cross sectors and (5) a coordinated approach to the assessment of research needs
New constraints from Central Chile on the origins of enriched continental compositions in thick-crusted arc magmas
Magmas from continental arcs built on thick crust have elevated incompatible element abundances and “enriched” radiogenic isotope ratios compared to magmas erupted in island and continental arcs overlying thinner crust. The relative influence of the slab, mantle, and upper plate on this variability is heavily debated. The Andean Southern Volcanic Zone (SVZ; 33-46° S) is an ideal setting to investigate the production of enriched continental arc compositions, because both crustal thickness and magma chemistry vary coherently along strike. However, the scarcity of primitive magmas in the thick-crusted northern SVZ has hindered
previous regional studies. To better address the origin of enriched continental compositions, we investigate the geochemistry (major and trace element abundances, 87Sr/86Sr and 143Nd/144Nd ratios) of new mafic samples from Don Casimiro and Maipo volcanoes in Diamante-Maipo Caldera Complex of the northern SVZ. While evolved Diamante-Maipo samples show evidence for crustal assimilation, the trace element and
isotopic enrichment of the most mafic samples cannot result from crustal processing, as no known regional or global basement lithologies are enriched in all of the necessary incompatible trace elements. Subduction
erosion models similarly fail to account for the enriched isotopic and trace element signature of these samples. Instead, we suggest that the enrichment of northern SVZ magmas is derived from an enriched ambient mantle component (similar to EM1-type ocean island basalts), superimposed on a northward decline in melt extent. A substantial, but nearly uniform contribution of melts from subducting sediment and altered oceanic crust are required at all latitudes. The EM1-like enrichment may arise from recycling of metasomatized subcontinental lithospheric mantle (M-SCLM), as the isotopic trajectory of primitive rear-arc monogenetic cones trend towards the compositions of SCLM melts sampled across South America. Isotopic data from spatially distributed rear-arc centres demonstrate that the arc-parallel variations in the degree of EM1-type enrichment observed in arc-front samples are also present up to 600 km behind the trench in the rear-arc. Rear-arc trace element systematics require significant but variable quantities of slab melts to be
transported to the mantle wedge at these large trench distances. Overall, we show that a unified model incorporating variable mantle enrichment, slab additions, and melt extents can account for along and acrossarc
trends within the SVZ. The recognition that mantle enrichment plays a key role in the production of enriched continental compositions in the SVZ has important implications for our understanding of the chemical evolution of the Earth. If ambient mantle enrichment is not taken into account, petrogenetic models of evolved lavas may overestimate the role of crustal assimilation, which, in turn, may lead models of
continental crust growth to overestimate the amount of continental material that has been recycled back into the mantle
Review of health economic models exploring and evaluating treatment and management of hospital-acquired pneumonia and ventilator-associated pneumonia
BACKGROUND: Hospital-acquired pneumonia (HAP) is pneumonia that occurs ≥48 h after hospital admission; it is the most common hospital-acquired infection contributing to death. Ventilator-associated pneumonia (VAP) arises ≥48-72 h after intubation. Opinions differ on whether VAP is a subset of HAP; the same pathogens predominate in both. Compared with VAP-free controls, patients developing VAP are twice as likely to die and have significantly longer stays in intensive care units. Guidelines recommend that microbiological cultures should guide antibiotic treatment, but these lack sensitivity and take 48-72 h to process, meaning that initial therapy must be empiric, generally with broad-spectrum agents. Given increasing pressure to improve both antibiotic stewardship and patient outcomes, the National Institute for Health and Care Excellence and the Infectious Diseases Society of America recommend research into rapid molecular diagnostic tests to identify causative organisms and their antibiotic resistances. Ideally, these would supersede culture, being quicker and more sensitive. In the UK, the INHALE research programme, funded by the National Institute for Health Research, is exploring rapid molecular diagnostics to inform treatment of HAP/VAP and, given resource implications, incorporates a health economic component. AIM: To identify previous economic modelling of HAP/VAP costs to inform this component. METHODS: Literature review of HAP/VAP studies with economic modelling identified from three databases. FINDINGS: Twenty studies were identified. Only one study specifically evaluated strategies to improve diagnosis; the remaining 19 studies omitted this important aspect. CONCLUSION: HAP/VAP modelling would be improved by better awareness of long-term outcomes and treatment complexity. To the authors' knowledge, no similar literature reviews of economic modelling for HAP/VAP have been published
A coherent middle Pliocene magnetostratigraphy, Wanganui Basin, New Zealand
We document magnetostratigraphies for three river sections (Turakina, Rangitikei, Wanganui) in Wanganui Basin and interpret them as corresponding to the Upper Gilbert, the Gauss and lower Matuyama Chrons of the Geomagnetic Polarity Timescale, in agreement with foraminiferal biostratigraphic datums. The Gauss-Gilbert transition (3.58 Ma) is located in both the Turakina and Wanganui River sections, while the Gauss-Matuyama transition (2.58 Ma) is located in all three sections, as are the lower and upper boundaries of the Mammoth (3.33–3.22 Ma) and Kaena (3.11–3.04 Ma) Subchrons. Our interpretations are based in part on the re-analysis of existing datasets and in part on the acquisition and analysis of new data, particularly for the Wanganui River section. The palaeomagnetic dates of these six horizons provide the only numerical age control for a thick (up to 2000 m) mudstone succession (Tangahoe Mudstone) that accumulated chiefly in upper bathyal and outer neritic palaeoenvironments. In the Wanganui River section the mean sediment accumulation rate is estimated to have been about 1.8 m/k.y., in the Turakina section it was about 1.5 m/k.y., and in the Rangitikei section, the mean rate from the beginning of the Mammoth Subchron to the Hautawa Shellbed was about 1.1 m/k.y. The high rates may be associated with the progradation of slope clinoforms northward through the basin. This new palaeomagnetic timescale allows revised correlations to be made between cyclothems in the Rangitikei River section and the global Oxygen Isotope Stages (OIS) as represented in Ocean Drilling Program (ODP) Site 846. The 16 depositional sequences between the end of the Mammoth Subchron and the Gauss-Matuyama Boundary are correlated with OIS MG2 to 100. The cyclothems average 39 k.y. in duration in our age model, which is close to the 41 k.y. duration of the orbital obliquity cycles. We support the arguments advanced recently in defence of the need for local New Zealand stages as a means of classifying New Zealand sedimentary successions, and strongly oppose the proposal to move stage boundaries to selected geomagnetic polarity transitions. The primary magnetisation of New Zealand mudstone is frequently overprinted with secondary components of diagenetic origin, and hence it is often difficult to obtain reliable magnetostratigraphic records. We suggest specific approaches, analytical methods, and criteria to help ensure robustness and coherency in the palaeomagnetic identification of chron boundaries in typical New Zealand Cenozoic mudstone successions
Foot Bone in Vivo: Its Center of Mass and Centroid of Shape
This paper studies foot bone geometrical shape and its mass distribution and
establishes an assessment method of bone strength. Using spiral CT scanning,
with an accuracy of sub-millimeter, we analyze the data of 384 pieces of foot
bones in vivo and investigate the relationship between the bone's external
shape and internal structure. This analysis is explored on the bases of the
bone's center of mass and its centroid of shape. We observe the phenomenon of
superposition of center of mass and centroid of shape fairly precisely,
indicating a possible appearance of biomechanical organism. We investigate two
aspects of the geometrical shape, (i) distance between compact bone's centroid
of shape and that of the bone and (ii) the mean radius of the same density bone
issue relative to the bone's centroid of shape. These quantities are used to
interpret the influence of different physical exercises imposed on bone
strength, thereby contributing to an alternate assessment technique to bone
strength.Comment: 9 pages, 4 figure
Heritability of Lumbar Trabecular Bone Mechanical Properties in Baboons
Genetic effects on mechanical properties have been demonstrated in rodents, but not confirmed in primates. Our aim was to quantify the proportion of variation in vertebral trabecular bone mechanical properties that is due to the effects of genes. L3 vertebrae were collected from 110 females and 46 male baboons (6–32 years old) from a single extended pedigree. Cranio-caudally oriented trabecular bone cores were scanned with microCT then tested in monotonic compression to determine apparent ultimate stress, modulus, and toughness. Age and sex effects and heritability (h2) were assessed using maximum likelihood-based variance components methods. Additive effects of genes on residual trait variance were significant for ultimate stress (h2 = 0.58), toughness (h2 = 0.64), and BV/TV (h2 = 0.55). When BV/TV was accounted for, the residual variance in ultimate stress accounted for by the additive effects of genes was no longer significant. Toughness, however, showed evidence of a non-BV/TV-related genetic effect. Overall, maximum stress and modulus show strong genetic effects that are nearly entirely due to bone volume. Toughness shows strong genetic effects related to bone volume and shows additional genetic effects (accounting for 10% of the total trait variance) that are independent of bone volume. These results support continued use of bone volume as a focal trait to identify genes related to skeletal fragility, but also show that other focal traits related to toughness and variation in the organic component of bone matrix will enhance our ability to find additional genes that are particularly relevant to fatigue-related fractures
Mathematical modelling long-term effects of replacing Prevnar7 with Prevnar13 on invasive pneumococcal diseases in England and Wales
England and Wales recently replaced the 7-valent pneumococcal conjugate vaccine (PCV7) with its 13-valent equivalent (PCV13), partly based on projections from mathematical models of the long-term impact of such a switch compared to ceasing pneumococcal conjugate vaccination altogether. A compartmental deterministic model was used to estimate parameters governing transmission of infection and competition between different groups of pneumococcal serotypes prior to the introduction of PCV13. The best-fitting parameters were used in an individual based model to describe pneumococcal transmission dynamics and effects of various options for the vaccination programme change in England and Wales. A number of scenarios were conducted using (i) different assumptions about the number of invasive pneumococcal disease cases adjusted for the increasing trend in disease incidence prior to PCV7 introduction in England and Wales, and (ii) a range of values representing serotype replacement induced by vaccination of the additional six serotypes in PCV13. Most of the scenarios considered suggest that ceasing pneumococcal conjugate vaccine use would cause an increase in invasive pneumococcal disease incidence, while replacing PCV7 with PCV13 would cause an overall decrease. However, the size of this reduction largely depends on the level of competition induced by the additional serotypes in PCV13. The model estimates that over 20 years of PCV13 vaccination, around 5000–62000 IPD cases could be prevented compared to stopping pneumococcal conjugate vaccination altogether. Despite inevitable uncertainty around serotype replacement effects following introduction of PCV13, the model suggests a reduction in overall invasive pneumococcal disease incidence in all cases. Our results provide useful evidence on the benefits of PCV13 to countries replacing or considering replacing PCV7 with PCV13, as well as data that can be used to evaluate the cost-effectiveness of such a switch
The structural invisibility of outsiders: the role of migrant labour in the meat-processing industry
This article examines the role of migrant workers in meat-processing factories in the UK. Drawing on materials from mixed methods research in a number of case study towns across Wales, we explore the structural and spatial processes that position migrant workers as outsiders. While state policy and immigration controls are often presented as a way of protecting migrant workers from work-based exploitation and ensuring jobs for British workers, our research highlights that the situation ‘on the ground’ is more complex. We argue that ‘self-exploitation’ among the migrant workforce is linked to the strategies of employers and the organisation of work, and that hyper-flexible work patterns have reinforced the spatial and social invisibilities of migrant workers in this sector. While this creates problems for migrant workers, we conclude that it is beneficial to supermarkets looking to supply consumers with the regular supply of cheap food to which they have become accustomed
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