6,691 research outputs found
A comparison of two position estimate algorithms that use ILS localizer and DME information. Simulation and flight test results
Simulation and flight tests were conducted to compare the accuracy of two algorithms designed to compute a position estimate with an airborne navigation computer. Both algorithms used ILS localizer and DME radio signals to compute a position difference vector to be used as an input to the navigation computer position estimate filter. The results of these tests show that the position estimate accuracy and response to artificially induced errors are improved when the position estimate is computed by an algorithm that geometrically combines DME and ILS localizer information to form a single component of error rather than by an algorithm that produces two independent components of error, one from a DMD input and the other from the ILS localizer input
Diabetic retinopathy and socioeconomic deprivation in Gloucestershire
Objectives To investigate socioeconomic variations in diabetes prevalence, uptake of screening for diabetic retinopathy, and prevalence of diabetic retinopathy. Methods The County of Gloucestershire formed the setting of the study. A cross-sectional study of people with diabetes was done on a countywide retinopathy-screening database. Diabetes prevalence with odds ratios, uptake of screening, prevalence of any retinopathy and prevalence of sight-threatening retinopathy at screening were compared for different area deprivation quintiles. Logistic regression was used to adjust for confounding. Results With each increasing quintile of deprivation, diabetes prevalence increased (odds ratio 0.84), the probability of having been screened for diabetic retinopathy decreased (odds ratio 1.11), and the prevalence of sight-threatening diabetic retinopathy among screened patients increased (odds ratio of 0.98), while the prevalence of non-sight-threatening diabetic retinopathy remained unchanged with each increasing quintile of deprivation. Conclusion Sight-threatening diabetic retinopathy was associated with socioeconomic deprivation, but non-sight-threatening diabetic retinopathy was not. Uptake of screening was inversely related to socioeconomic deprivation
Quantifying and resolving multiple vector transformants in S. cerevisiae plasmid libraries
<p>Abstract</p> <p>Background</p> <p>In addition to providing the molecular machinery for transcription and translation, recombinant microbial expression hosts maintain the critical genotype-phenotype link that is essential for high throughput screening and recovery of proteins encoded by plasmid libraries. It is known that <it>Escherichia coli </it>cells can be simultaneously transformed with multiple unique plasmids and thusly complicate recombinant library screening experiments. As a result of their potential to yield misleading results, bacterial multiple vector transformants have been thoroughly characterized in previous model studies. In contrast to bacterial systems, there is little quantitative information available regarding multiple vector transformants in yeast. <it>Saccharomyces cerevisiae </it>is the most widely used eukaryotic platform for cell surface display, combinatorial protein engineering, and other recombinant library screens. In order to characterize the extent and nature of multiple vector transformants in this important host, plasmid-born gene libraries constructed by yeast homologous recombination were analyzed by DNA sequencing.</p> <p>Results</p> <p>It was found that up to 90% of clones in yeast homologous recombination libraries may be multiple vector transformants, that on average these clones bear four or more unique mutant genes, and that these multiple vector cells persist as a significant proportion of library populations for greater than 24 hours during liquid outgrowth. Both vector concentration and vector to insert ratio influenced the library proportion of multiple vector transformants, but their population frequency was independent of transformation efficiency. Interestingly, the average number of plasmids born by multiple vector transformants did not vary with their library population proportion.</p> <p>Conclusion</p> <p>These results highlight the potential for multiple vector transformants to dominate yeast libraries constructed by homologous recombination. The previously unrecognized prevalence and persistence of multiply transformed yeast cells have important implications for yeast library screens. The quantitative information described herein should increase awareness of this issue, and the rapid sequencing approach developed for these studies should be widely useful for identifying multiple vector transformants and avoiding complications associated with cells that have acquired more than one unique plasmid.</p
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Evaluation of Electromagnetic Induction as a Noninvasive Technique for Monitoring Water Movement into and Beneath Waste Disposal Facilities
The purpose of this study was to evaluate the use of electromagnetic induction to noninvasively monitor water content in waste disposal facility cover soils. We compared apparent electrical conductivity measurements monitored with the EM38 ground conductivity meter with water content monitored with a neutron probe at 20 locations over an 18-month period from August 1998 to January 2000. Two cover designs were monitored: a gel/asphalt barrier at 1.3 m depth and a capillary barrier at 2.0 m depth. The EM38 instrument was operated in both the vertical and horizontal dipole modes with the instrument resting on the ground surface and all data were normalized to 25°C. Linear regression techniques were applied to analyze the survey data. Water content to a depth of 0.75 m was correlated with horizontal dipole mode data and water content to depths of 1.1 m and 1.5 m was correlated with vertical dipole mode data. Initially higher water content values decreased by an average of 0.10 m^3/m^3 in the top 0.75 m and an average of 0.07 m^3/m^3 in the top 1.5 m over the course of the study. The regression model of the EM38 vertical dipole mode data with water content to the 1.5 m depth for all locations monitored on the capillary barrier design resulted in a standard deviation of 0.016 m^3/m^3. Horizontal dipole mode data correlated with water content to the 0.75 m depth had a standard deviation of 0.022 m^3/m^3 for all locations on both barrier designs. Models at individual survey locations generally exhibited much smaller standard deviations, ranging from 0.005 to 0.018 m^3/m^3 and averaging 0.010 m^3/m^3. The smaller standard deviations and general similarity of regression slope values of the models at individual locations indicate that this technique is more accurate as an indicator of changes in water content than as an indicator of the absolute value of water content at a given location. Sources of variability were attributed to horizontal and vertical variation in soil salinity, the vertical distribution of water at the time of a particular survey, and subtle differences in topsoil thickness and surface roughness. Results indicate that electromagnetic induction is useful for evaluating infiltration. The EM technique resulted in standard deviation values for water content similar to those of the neutron probe method but is capable of monitoring larger areas much more rapidly and at a lower cost.Bureau of Economic Geolog
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Evaluation of Groundwater Nitrate Contamination in Major Aquifers in Texas
Nitrate is the most widespread groundwater contaminant in Texas and in the U.S. There are many potential adverse health implications of elevated groundwater nitrate, including methemoglobinemia and cancer risks. There are a variety of sources of nitrate, including natural sources, inorganic and organic fertilizers (manure), output from concentrated animal feeding operations (CAFOs), septic tanks, and leaking sewer systems. Natural sources result from nitrogen fixation by legumes, mineralization of organic matter (nitrification), and natural geologic sources.
Many previous studies have been conducted on groundwater nitrate contamination in Texas. The early studies focused on source identification using nitrogen isotopes, mainly distinguishing between nitrate from fertilizers and septic tanks. Groundwater nitrate levels were expected to be high in the Ogallala Aquifer beneath playas adjacent to concentrated animal feeding operations; however, many studies showed that nitrate levels were reduced by denitrification attributed to high levels of organic matter. A recent study suggested that nitrate contamination has been increasing in the state over the past several decades and identified the Seymour aquifer in the Rolling Plains as a hotspot of groundwater nitrate contamination. A study evaluated controls on groundwater nitrate contamination using logistic regression, indicating that precipitation, percent of agricultural land, low-density residential land, and soil organic matter were the dominant explanatory variables. Unsaturated zone sampling was used to link land surface processes to groundwater nitrate levels and suggested that much of the elevated nitrate levels in the Ogallala and Seymour aquifers could be attributed to high levels of natural nitrate prior to cultivation that was oxidized during cultivation and mobilized into the underlying aquifer.
The current study examined the distribution of groundwater nitrate in major and minor aquifers in the state using approximately 10,000 analyses from major aquifers and approximately 2,000 analyses from minor aquifers. Approximately 70% of the samples in the major and minor aquifers exceeded the detection levels for nitrate. The majority of the samples are from rural domestic and irrigation wells. A total of 5.5% of the samples from the major aquifers exceeded the MCL, with the highest level of contamination in the Seymour Aquifer (61% of sampled > MCL), followed by the Pecos Valley Aquifer (11%), Ogallala Aquifer (9%), Edwards Trinity High Plains (6%), and the remaining major aquifers < 2%. Groundwater nitrate concentrations generally decreased with depth.Bureau of Economic Geolog
The Strength of a Smile: Duchenne Smiles Improve Advertisement and Product Evaluations
Consumer research recognizes the well-established effect of positive emotions on consumers, i.e. consumers in positive moods tend to give positive evaluations of products and advertisements. Recently, researchers have investigated the use of Duchenne smiles (genuine smiles) in advertisements to evoke positive emotions and lead to positive evaluations. Duchenne smiles are identified by the activation of both the zygomaticus major muscle (which pulls up the corners of the mouth) and the orbicularis oculi muscles (which surround the eye and result in the crow’s feet wrinkles). Peace, Miles, and Johnston (2006) demonstrated that including Duchenne smiles in mock print advertisements affects viewers’ perceptions of the ad and featured product, resulting in more positive evaluations as compared to neutral and non-Duchenne advertisements. The current research expands on Peace et al. and examines the effects of type of smile displayed in mock print advertisements that feature inexpensive and expensive products alike. Participants rated pairs of advertisements created by the researchers. Participants significantly preferred Duchenne smiling advertisements over non Duchenne and also showed significant preference in their likelihood to purchase products in Duchenne advertisements. A potential mimicry association mechanism is discussed, as well as practical implications for advertisers
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Assessment of Groundwater Contamination, in Situ Treatment, and Disposal of Treatment Residuals in the Vicinity of Lubbock, Texas
This report presents an assessment of groundwater contamination potential, in situ treatment technologies for drinking water supply, and assessment of injecting ex situ treatment residuals into the source aquifer in the vicinity of Lubbock, Texas. The study area surrounding Lubbock includes the following nine counties: Lubbock, Lamb, Hale, Floyd, Crosby, Garza, Lynn, Terry, and Hockley Counties. Many public water supply wells in the region exceed the maximum contaminant levels (MCLs) for the following water quality constituents of concern (COCs): nitrate (NO3), arsenic (As), fluoride (F), selenium (Se), uranium (U), and radium-226 (Ra-226), and radium-228 (Ra-228).
The study was divided into three main tasks: (1) stratification of naturally occurring contaminants in groundwater; (2) potential for in situ treatment; and (3) potential for disposal of treatment residuals in drinking water. Task 1 was conducted by the Bureau of Economic Geology, and tasks 2 and 3 were conducted by CH2M Hill under subcontract to the Bureau of Economic Geology.Bureau of Economic Geolog
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An analysis of media reporting on the closure of freestanding midwifery units in England
PROBLEM: Despite clinical guidelines and policy promoting choice of place of birth, 14 Freestanding Midwifery Units were closed between 2008 and 2015, closures justified by low use and financial constraints.
BACKGROUND: The Birthplace in England Programme found that freestanding midwifery units provided the most cost-effective birthplace for women at low risk of complications. Women planning birth in a freestanding unit were less likely to experience interventions than those planning obstetric unit birth, with no difference in outcomes for babies.
METHODS: This paper uses an interpretative technique developed for policy analysis to explore the representation of these closures in 191 news articles, to explore the public climate in which they occurred.
FINDINGS AND DISCUSSION: The articles focussed on underuse by women and financial constraints on services. Despite the inclusion of service user voices, the power of framing was held by service managers and commissioners. The analysis exposed how neoliberalist and austerity policies has privileged representation of individual consumer choice and market-driven provision as drivers of changes in health services. This normative framing makes the reasons given for closure as hard to refute and cultural norms persist that birth is safest in an obstetric setting, despite evidence to the contrary.
CONCLUSION: The rise of neoliberalism and austerity in contemporary Britain has influenced the reform of maternity services, in particular the closure of midwifery units. Justifications given for closure silence other narratives, predominantly from service users, that attempt to present women's choice in terms of rights and a social model of care
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Identification of geographic areas in Texas suitable for groundwater banking
The population in Texas is expected to double in the next 50 years, increasing from approximately 21 million in 2000 to approximately 40 million by 2050. During this same period, water demand is projected to increase by 18 percent, from nearly 17 to 20 million acre-feet. Texas' water supplies are also diminishing as a result of droughts, historical and ongoing overdrafts of aquifers in excess of natural recharge rates, pollution of available supplies, and limitations on use that result from environmental regulation such as total maximum daily load requirements and requirements of the Endangered Species Act. Despite increasing demand and dwindling supply, only eight surface water reservoirs with conservation storage greater than 5,000 acre-feet are expected to be built in the next 50 years. Consequently, alternative approaches will be required to meet future water demand, particularly during periods of drought.
One approach to meet the increasing water demand is to artificially recharge groundwater supplies with excess surface water. Artificial recharge of groundwater, or "groundwater banking," is becoming more common in the U.S., particularly in semiarid states such as California and Arizona, as a means to manage water resources and meet water demands during periods of extended droughts. The storage volume available in aquifers is generally much greater than that available in surface reservoirs.
This report documents a study performed by Daniel B. Stephens & Associates, Inc. and the Bureau of Economic Geology on behalf of the Texas Water Development Board. The goal for this project was to identify regions in Texas that are potentially suitable for groundwater banking. Although there are a variety of methods for artificially recharging aquifers with surface water, this study only considered recharge from spreading (or infiltration) basins on the land surface, although an overview of other techniques and examples of their application in Texas is provided.Bureau of Economic Geolog
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