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Fast ice flow is associated with the deformation of subglacial sediment. Seismic shear velocities, Vs, increase with the rigidity of material and hence can be used to distinguish soft sediment from hard bedrock substrates. Depth profiles of Vs can be obtained from inversions of Rayleigh wave dispersion curves, from passive or active-sources, but these can be highly ambiguous and lack depth sensitivity. Our novel Bayesian transdimensional algorithm, MuLTI, circumvents these issues by adding independent depth constraints to the inversion, also allowing comprehensive uncertainty analysis. We apply MuLTI to the inversion of a Rayleigh wave dataset, acquired using active-source (Multichannel Analysis of Surface Waves) techniques, to characterise sediment distribution beneath the frontal margin of Midtdalsbreen, an outlet of Norway's Hardangerjøkulen ice cap. Ice thickness (0–20 m) is constrained using co-located GPR data. Outputs from MuLTI suggest that partly-frozen sediment (Vs 500–1000 m s−1), overlying bedrock (Vs 2000–2500 m s−1), is present in patches with a thickness of ~4 m, although this approaches the resolvable limit of our Rayleigh wave frequencies (14–100 Hz). Uncertainties immediately beneath the glacier bed are <280 m s−1, implying that MuLTI cannot only distinguish bedrock and sediment substrates but does so with an accuracy sufficient for resolving variations in sediment properties.
Combined archaeological, ecological, and geologic research on Chuginadak and Carlisle Islands in the Islands of Four Mountains (IFM) probed questions about the sustainability of human settlements over the past 4000 years in the face of geologic, ecological, and social hazards. We use a human ecodynamics approach to frame the investigation and present original archaeological evidence from this poorly known region of the remote Aleutian Islands. Several village sites occupied during the last four millennia are clustered in locations that were not damaged by earthquake-induced tsunamis; however, new geologic evidence indicates that at least one volcanic eruption forced humans to abandon one or more prehistoric village sites. Combined archaeological, ecological, and geologic analyses demonstrate resilient Unangax̂ occupations of the IFM through long-term climate change as well as earthquakes, tsunamis, and volcanic eruptions with occasional community vulnerability to volcanic eruptions.
The conservation benefits of maintaining social groupings during and after animal translocations are unclear. Although some studies report improved post-release survival, others found no discernible influence on reintroduction success. Understanding the effects of social groupings is difficult because release methods can influence the animals’ ability to maintain social groups. We explored this relationship by first studying whether release protocols influenced post-release cohesion in the communal burrowing bettong Bettongia lesueur, and then investigating whether maintenance of social cohesion conferred any post-release advantage. We released bettongs into a small (8 ha) and large (2,600 ha) area and compared the proportion that maintained social groupings in the different settings. The proportion of bettongs sharing with previous warren co-occupants was higher than expected by chance in both areas, however, a significantly higher proportion of bettongs maintained social groupings in the small (75%) compared to the large release area (13%). This suggests bettongs prefer to maintain social groupings but are unable to locate members of their group in large release areas. Bettongs that did maintain social groupings showed no difference in reproductive or health outcomes compared to those that formed new social groupings, suggesting no benefit to reintroduction success. We conclude that release protocols can influence post-release cohesion, but that greater cohesion does not necessarily confer advantages to group-living animals. To test the importance of social cohesion, further research on reintroductions should compare post-release parameters for animals released using protocols that do and do not facilitate maintenance of social groupings.
To understand the effects of interviewers on the responses they collect for measures of food security, income and selected survey quality measures (i.e. discrepancy between reported Supplemental Nutrition Assistance Program (SNAP) status and administrative data, length of time between initial and final interview, and missing income data) in the US Department of Agriculture’s National Household Food Acquisition and Purchase Survey (FoodAPS).
Using data from FoodAPS, multilevel models with random interviewer effects were fitted to estimate the variance in each outcome measure arising from effects of the interviewers. Covariates describing each household’s socio-economic status, demographics and experience in taking the survey, and interviewer-level experience were included as fixed effects. The variance components in the outcomes due to interviewers were estimated. Outlier interviewers were profiled.
Non-institutionalized households in the continental USA (April 2012–January 2013).
Individuals (n 14 317) in 4826 households who responded to FoodAPS.
There was a substantial amount of variability in the distributions of the outcomes examined (i.e. time between initial and final interview, reported values for food security, individual income, missing income) among the FoodAPS interviewers, even after accounting for the fixed effects of the household- and interviewer-level covariates and removing extreme outlier interviewers.
Interviewers may introduce error in food acquisition survey data when they are asked to interact with the respondents. Managers of future surveys with similarly complex data collection procedures could consider using multilevel models to adaptively identify and retrain interviewers who have extreme effects on data collection outcomes.
We present the results of simulations that explore the variety of accretion flows possible in magnetic cataclysmic variables (mCVs). Our simulations evolve to equilibrium periods spanning 0.01 < Рspin/Рorb < 0.6 and the resulting flows vary from disc-fed systems at Рspin/Рorb ~ 0.01 - 0.1, to stream fed systems at Рspin/Рorb ~ 0.1 - 0.5 and systems fed from a ring at the outer edge of the white dwarf's Roche lobe at Рspin/Рorb ~ 0.6.
The present report of Commission 15 has been, as usual, prepared primarily by the chairpersons of the two working groups. E. Tedesco wrote the section about Asteroids and Meteorites, with the assistance of A. Cellino, G. Consolmagno and C.-I. Lagerkvist. W. F. Huebner prepared the section about Comets, with the assistance of J. Benkhoff, H. Boehnhardt, J. Brandt, M. T. Capria, A. Cochran, G. Cremonese, M. Duncan, W. Huntress, H. Levison, and G. P. Tozzi. Moreover, the whole document has been assembled by K. Muinonen, who did the final editing, to merge the two reports and fit the document into the allotted space. Material taken from both major areas regarding the relationship between comets and asteroids has been combined into a single section.
The impact of the Supplemental Nutrition Assistance Program (SNAP) on the national economy is examined using a general equilibrium model and comparing measures of the economy from 2010 to a simulation of that economy without SNAP. Without the SNAP program, the overall size of the economy hardly differs—demand for labor increases slightly. However, households that would be eligible for SNAP experience a net loss. They have 5.5 percent less disposable income while ineligible households have approximately 1 percent more income without SNAP, and output of products eligible for purchase with SNAP funds declines approximately one billion dollars.
Currently 67 % of the US population is overweight or obese and obesity is associated with several chronic medical conditions. Geographic areas where individuals lack access to healthy foods have been termed ‘food deserts’. The study aim was to examine if area of residence within Metro Detroit was associated with dietary intake, food and shopping behaviours, and BMI.
Participants were recruited in the waiting area of four primary-care clinics.
Individuals (n 1004) completed a questionnaire comprising four sections: demographics; personal health status including self-reported height and weight; a modified diet, transportation and shopping survey; and a subscale from the Diet and Health Knowledge Survey.
Seventy-four per cent of participants were female and the mean age was 46·7 (sd 15·0) years. In univariate analyses, living in Detroit was associated with being African American, unemployment, less education, no regular exercise, worse health self-rating and obesity (P < 0·0005 for all). Participants living in Detroit had a 3·06 (95 % CI 1·91, 4·21) kg/m2 larger BMI compared with people living outside the city (P < 0·0005) in univariate analyses, but the effect was attenuated when adjusted for demographics, disease status, shopping and eating behaviours, dietary intakes and diet knowledge (β = −0·46 kg/m2, 95 % CI −2·23, 1·30 kg/m2, P = 0·60).
Overweight and obesity are highly prevalent both inside (82·9 %) and outside (72·8 %) the city of Detroit, presenting a major public health problem. However, living in this food desert was not significantly associated with BMI after potential covariates were considered.
Uniformly uni-axially aligned electrodes are formed by uniaxially cracking an indium tin oxide, ITO, film vacuum deposited on a polyester substrate. The cracks are produced by bending the film around a small radius of curvature, producing narrow, parallel cracks in the ITO separated by 5-10 μm. The cracks are enhanced by etching or uniaxial stretching. Heating and stretching is the most effective, producing a crack width of about 0.05 μm and a differential conductivity (measured parallel and perpendicular to the cracks) several orders of magnitude or greater. A passive matrix bistable cholesteric display is fabricated using top and bottom substrates with perpendicularly aligned electrodes. The addressed lines on each substrate are defined by the contact electrode, which contacts multiple cracked ITO lines. Because of the small dimension of the cracks (much less than the thickness of the active layer) they are not visible in the display. The separation between the contact electrodes must be great than 20 μm in order to include at least one crack and electrically isolate each individual line. The resulting display demonstrates how controlled cracking of ITO can replace photolithographic etching of ITO or printing of conducting polymers to produce the line electrodes required for flexible, passive matrix displays and related electronic applications. Un-axially cracking can be easily integrated into a roll-to-roll manufacturing process.
The chemical stability of a GaAs layer structure consisting of a thin (10 nm) layer of low-temperature-grown GaAs (LTG:GaAs) on a heavily n-doped GaAs layer, both grown by molecular beam epitaxy, is described. Scanning tunneling spectroscopy and X-ray photoelectron spectroscopy performed after atmospheric exposure indicate that the LTG:GaAs surface layer oxidizes much less rapidly than comparable layers of stoichiometric GaAs. There is also evidence that the terminal oxide thickness is smaller than that of stoichiometric GaAs. The spectroscopy results are used to confirm a model for conduction in low resistance, nonalloyed contacts employing comparable layer structures. The inhibited surface oxidation rate is attributed to the bulk Fermi level pinning and the low minority carrier lifetime in unannealed LTG:GaAs. Device applications including low-resistance cap layers for field-effect transistors are described.
The solar cells employed in low to medium (50 to 200 suns) concentration photovoltaic (CPV) are usually mono-crystalline silicon. Laser Groove Buried Contacts (LGBC) are preferred to screen printing in these cells due to the high currents generated in the system. In this paper, we report on the use of Coherence Correlation Interferometry (CCI) to accurately measure the width and depth of the laser-ablated grooves. In addition, the technique is also used to measure the surface roughness at the bottom of the trenches, since this can determine the success of the subsequent plating process, and at the top surface to optimize the debris control and obtain clean surfaces and well-shaped groove edges. The laser ablation process was also optimized to obtain the groove aspect ratio and surface quality required. Process parameters to be controlled include laser power, pulse energy, stage speed and focal length. The CCI technique is capable of providing all the groove and surface metrology required for this process optimization.
The range of foodstuffs that can be produced by Scottish agriculture depends chiefly on the nature of the soils and the prevailing climate. The landform of Scotland and some of its physical features are discussed in terms of its geology, and the nature of its present-day soils in relation to parent materials is summarized. The agriculturally useful soils have been mapped, inventoried and characterized by the Soil Survey of Scotland and other departments of the Macaulay Institute for Soil Research. The limitations imposed by the soils, their geographical latitude, altitude, aspect, slope, the prevailing weather in their locality, etc., are taken into account in the Land Capability for Agriculture (LCA) assessment. Examples are given of several physical and chemical characteristics which are dominant in Scottish soils and which are of particular significance to the production of foodstuffs.