5,310 research outputs found
Data Recovery Efforts at the Millville Mill Site (41RK223), Rusk County, Texas
In September 1993, data recovery efforts were undertaken by Espey, Huston & Associates, Inc. (EH&A) of Austin, Texas, to mitigate the effects of lignite mining on site 41RK223 in Texas Utilities Mining Company\u27s Oak Hill/2280 Acre Mine permit area of north-central Rusk County, Texas. The data recovery efforts were planned and conducted in coordination with the Department of Antiquities Protection at the Texas Historical Commission (THC) and Mr. Matthew Tanner of TU Services. The site was originally recorded by EH&A during a 1989 survey of the Oak Hill/2280 Acre Mine permit area based on information received from local informants, Orville Todd and Herman Ballow. Both men recalled swimming as children in the vicinity of an old framework of heavy timbers submerged within Boggy Branch, a tributary to Mill Creek. Local history accounts suggested that the timbers were likely the remains of one of several old water-powered mills historically associated with the Mill Creek floodplain
Solid-propellant rocket motor internal ballistic performance variation analysis, phase 2
The Monte Carlo method was used to investigate thrust imbalance and its first time derivative throughtout the burning time of pairs of solid rocket motors firing in parallel. Results obtained compare favorably with Titan 3 C flight performance data. Statistical correlations of the thrust imbalance at various times with corresponding nominal trace slopes suggest several alternative methods of predicting thrust imbalance. The effect of circular-perforated grain deformation on internal ballistics is discussed, and a modified design analysis computer program which permits such an evaluation is presented. Comparisons with SRM firings indicate that grain deformation may account for a portion of the so-called scale factor on burning rate between large motors and strand burners or small ballistic test motors. Thermoelastic effects on burning rate are also investigated. Burning surface temperature is calculated by coupling the solid phase energy equation containing a strain rate term with a model of gas phase combustion zone using the Zeldovich-Novozhilov technique. Comparisons of solutions with and without the strain rate term indicate a small but possibly significant effect of the thermoelastic coupling
A Monte Carlo investigation of thrust imbalance of solid rocket motor pairs
A technique is described for theoretical, statistical evaluation of the thrust imbalance of pairs of solid-propellant rocket motors (SRMs) firing in parallel. Sets of the significant variables, determined as a part of the research, are selected using a random sampling technique and the imbalance calculated for a large number of motor pairs. The performance model is upgraded to include the effects of statistical variations in the ovality and alignment of the motor case and mandrel. Effects of cross-correlations of variables are minimized by selecting for the most part completely independent input variables, over forty in number. The imbalance is evaluated in terms of six time - varying parameters as well as eleven single valued ones which themselves are subject to statistical analysis. A sample study of the thrust imbalance of 50 pairs of 146 in. dia. SRMs of the type to be used on the space shuttle is presented. The FORTRAN IV computer program of the analysis and complete instructions for its use are included. Performance computation time for one pair of SRMs is approximately 35 seconds on the IBM 370/155 using the FORTRAN H compiler
Solid propellant rocket motor internal ballistics performance variation analysis, phase 3
Results of research aimed at improving the predictability of off nominal internal ballistics performance of solid propellant rocket motors (SRMs) including thrust imbalance between two SRMs firing in parallel are reported. The potential effects of nozzle throat erosion on internal ballistic performance were studied and a propellant burning rate low postulated. The propellant burning rate model when coupled with the grain deformation model permits an excellent match between theoretical results and test data for the Titan IIIC, TU455.02, and the first Space Shuttle SRM (DM-1). Analysis of star grain deformation using an experimental model and a finite element model shows the star grain deformation effects for the Space Shuttle to be small in comparison to those of the circular perforated grain. An alternative technique was developed for predicting thrust imbalance without recourse to the Monte Carlo computer program. A scaling relationship used to relate theoretical results to test results may be applied to the alternative technique of predicting thrust imbalance or to the Monte Carlo evaluation. Extended investigation into the effect of strain rate on propellant burning rate leads to the conclusion that the thermoelastic effect is generally negligible for both steadily increasing pressure loads and oscillatory loads
Seventy years of sex education in Health Education Journal: a critical review
This paper examines key debates and perspectives on sex education in Health Education Journal (HEJ), from the date of the journal’s first publication in March 1943 to the present day. Matters relating to sexuality and sexual health are revealed to be integral to HEJ’s history. First published as Health and Empire (1921 – 1942), a key purpose of the journal since its inception has been to share information on venereal disease and its prevention within the UK and across the former British Empire. From 1943 to the present day, discussions on sex education in the newly-christened HEJ both reflect and respond to evolving socio-cultural attitudes towards sexuality in the UK. Changing definitions of sex education across the decades are examined, from the prevention of venereal disease and moral decline in war-time Britain in the 1940s, to a range of responses to sexual liberation in the 1960s and 1970s; from a focus on preventing sexually-transmitted infections, teenage pregnancy and HIV in the 1980s, to the provision of sexual health services alongside sex education in the 2000s. Over the past 70 years, a shift from prevention of pre-marital sexual activity to the management of its outcomes is apparent; however, while these changes over time are notable, perhaps the most striking findings of this review are the continuities in arguments for and against the discussion of sexual issues. After more than 70 years of debate, it would seem that there is little consensus concerning motivations for and the content of sex education
From calibration to implementation: stage-structured population forecasts for the vector of Lyme disease (ixodes scapularis) across the Eastern United States
In the United States, the total confirmed and probable cases of Lyme disease have more than doubled in the past decade. The increase in human incidence has been attributed, in part, to the range expansion of the principal vector of the bacterial pathogen, the black-legged tick (Ixodes scapularis). The tick life cycle includes three distinct hematophagous stages, each with different temporal and spatial influence on tick infection and human exposure. Therefore, a model that accurately predicts the dynamics of all life stages would be more accurate in describing the risk of encountering a tick-borne disease (TBD).
To this end, I sought out to develop process-based models grounded in ecological theory and community ecology to make quantitative predictions of questing tick populations. Furthermore, the ultimate goal was to produce iterative, short (< 31 days) to intermediate (6 month - 1 year) forecasts on a daily basis in areas of the United States where Lyme disease is endemic.
In Chapter 1, I built stage-structured population models in a data fusion framework that incorporates environmental variables such as the host population, relative humidity, and temperature, to predict the questing population of each life stage. I found that a four-stage model that includes the ecologically relevant dormant overwintering nymph state outperforms other models. The interplay between weather and host populations was also predictive.
In Chapter 2, I describe a data-assimilation scheme developed to update the tick population model iteratively and evaluate forecast uncertainty and sensitivities. Larval abundances were spatially heterogeneous, likely due to their limited dispersal capacity, and sampling efforts at this stage were less likely to reduce forecast uncertainty than efforts at later stages.
Chapter 3 evaluates the transferability and the structural components of this model for I. scapularis and Amblyomma americanum populations at NEON. A. americanum is arguably the second-most medically important tick species in the US. In general, forecasts were biased and tended to overpredict both species, this trend was on a latitudinal gradient, and forecasts for I. scapularis were more skillful than for A. americanum. Given the model framework, it appears that mouse abundance is less predictive of ticks at NEON than at Cary.
In Chapter 4, I estimated tick density at NEON sites and is used these estimates to constrain the parasitism state of mice through time, which has important implications for TBD management. Knowing when mice are parasitized could lead to management actions for mice removal and is another proxy for disease risk as this information tells us when ticks are active.
Overall, this dissertation focused on building mechanistic ecological forecasts from the ground up. I started with model calibration, then built a data assimilation scheme, and tested it at sites across the US. Therefore, this work represents the first of its kind pipeline from ecological model calibration to forecast implementation
Response of selected microorganisms to experimental planetary environments
Experiments indicate that hardy organisms will likely grow in the Martian environment if moisture is available, and that these organisms definitely present a threat to contamination of the biopackage if they are transported to the surface of Mars
BioWorkbench: A High-Performance Framework for Managing and Analyzing Bioinformatics Experiments
Advances in sequencing techniques have led to exponential growth in
biological data, demanding the development of large-scale bioinformatics
experiments. Because these experiments are computation- and data-intensive,
they require high-performance computing (HPC) techniques and can benefit from
specialized technologies such as Scientific Workflow Management Systems (SWfMS)
and databases. In this work, we present BioWorkbench, a framework for managing
and analyzing bioinformatics experiments. This framework automatically collects
provenance data, including both performance data from workflow execution and
data from the scientific domain of the workflow application. Provenance data
can be analyzed through a web application that abstracts a set of queries to
the provenance database, simplifying access to provenance information. We
evaluate BioWorkbench using three case studies: SwiftPhylo, a phylogenetic tree
assembly workflow; SwiftGECKO, a comparative genomics workflow; and RASflow, a
RASopathy analysis workflow. We analyze each workflow from both computational
and scientific domain perspectives, by using queries to a provenance and
annotation database. Some of these queries are available as a pre-built feature
of the BioWorkbench web application. Through the provenance data, we show that
the framework is scalable and achieves high-performance, reducing up to 98% of
the case studies execution time. We also show how the application of machine
learning techniques can enrich the analysis process
A Cross-Sectional Investigation of the Determinants of Urban Residential Water Demand in the United States, 1960 and 1970
This research was undertaken to specify and estimate a model relating household demand for urban water to its principal determinants. Four specific tasks were accomplished:
1. An appropriate economic demand model for urban-residential water supplies was postulated. An improved specification of the rainfall variable was developed to account for turf maintenance demand. The price of water was specified in exponential form making its elasticity price dependent.
2. Parameters of the model were estimated based on pooled data representing a cross-section of U.S. cities.
3. Parameters were estimated for a regionalized version of the model by incorporating sets of dummy variables. Tests for statistical differences among key economic coefficients were made to ascertain regional differences, if any.
4. Parameters were estimated for a model disaggregated by size-of-city categories again by incorporating dummy variable sets. Tests for statistical differences among key economic coefficients were made to ascertain differences among size-of-city categories, if any.
The demand models were fitted using 1960 and 1970 data and ordinary least squares regression techniques. Explanatory variables included price, income, precipitation (during the defined growing season) and number of residents per meter in addition to sets of dummy variables on the constant factor and price and income coefficients. The results suggest that size of city is not statistically significant in determining the residential demand for urban water. However, regional differences are significant.
For the regional model, price, income, and residents per meter were significant at the 1 percent level for the 1960 data; price and precipitation were significant at the 1 percent level for the 1970 data. R2-values were .74 and .71 for the 1960 and 1970 data, respectively.
Income and price elasticities are presented for all regions at the mean price level and for one standard deviation above and below this price level. Mean price level elasticities ranged between -.30 and -.82 and between -.33 and -.67 for the 1960 and 1970 data, respectively, suggesting an inelastic residential water demand at present price levels. The elasticity estimates derived from the regional coefficients of this study compare favorably with those of earlier more micro-level analyses
Descendants of the Jurassic turiasaurs from Iberia found refuge in the Early Cretaceous of western USA
A new, largely complete eusauropod dinosaur with cranial and postcranial elements from two skeletons, Mierasaurus bobyoungi gen. nov., sp. nov. from the lower Yellow Cat Member (Early Cretaceous) of Utah (USA), is the first recognized member of Turiasauria from North America. Moreover, according to our phylogenetic results, Moabosaurus utahensis from the lower Yellow Cat Member of Utah (USA) is also a member of this clade. This group of non-neosauropod eusauropods, which now includes five genera (Losillasaurus, Turiasaurus, Mierasaurus, Moabosaurus and Zby), was previously known only from the Jurassic of Europe. These recent discoveries in Utah suggest that turiasaurs as a lineage survived the Jurassic-Cretaceous extinction boundary and expanded their known range, at least, into western North America. The revised spatiotemporal distribution of turiasaurs is consistent with the presence of a land connection between North America and Europe sometime during the late Tithonian to Valanginian (c.147-133 Ma). Mierasaurus and Moabosaurus are the only non-neosauropod eusauropods known from North America, despite being younger than the classic neosauropods of the Morrison Formation (c.150 Ma)
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