2,635 research outputs found
Development of the health and economic consequences of smoking interactive model
Objective-To describe the health and economic consequences of smoking model, a user friendly, web based tool, designed to estimate the health and economic outcomes associated with smoking and the benefits of smoking cessation. Results-An overview of the development of the model equations and user interface is given, and data from the UK are presented as an example of the model outputs. These results show that a typical smoking cessation strategy costs approximately pound 1200 per life year saved and pound 22 000 per death averted. Conclusions-The model successfully captures the complexity required to model smoking behaviour and associated mortality, morbidity, and health care costs. Furthermore, the interface provides the results in a simple and flexible way so as to be useful to a variety of audiences and to simulate a variety of smoking cessation methods
X-ray rocking curve study of Si-implanted GaAs, Si, and Ge
Crystalline properties of Si-implanted GaAs, Si, and Ge have been studied by Bragg case double-crystal x-ray diffraction. Sharp qualitative and quantitative differences were found between the damage in GaAs on one hand and Si and Ge on the other. In Si and Ge the number of defects and the strain increase linearly with dose up to the amorphous threshold. In GaAs the increase in these quantities is neither linear nor monotonic with dose. At a moderate damage level the GaAs crystal undergoes a transition from elastic to plastic behavior. This transition is accompanied by the creation of extended defects, which are not detected in Si or Ge
Development of a severe local storm prediction system: A 60-day test of a mesoscale primitive equation model
The progress and problems associated with the dynamical forecast system which was developed to predict severe storms are examined. The meteorological problem of severe convective storm forecasting is reviewed. The cascade hypothesis which forms the theoretical core of the nested grid dynamical numerical modelling system is described. The dynamical and numerical structure of the model used during the 1978 test period is presented and a preliminary description of a proposed multigrid system for future experiments and tests is provided. Six cases from the spring of 1978 are discussed to illustrate the model's performance and its problems. Potential solutions to the problems are examined
Low Voltage Flexible Sequence Automatic Controls
The controls described in this bulletin meet the functional demands of automation on the farm- stop and start sequence, flexible connections, delays, low voltage signalling, unitization, and equipment protection. In meeting the functional demands, these controls overcome the limitations of custom designed control circuits using standard components. Also by allowing use of hours instead of horsepower, these controls normally permit installation of an automatic feeding system at a lower cost than comparable push button mechanized systems. This low voltage, flexible sequence control system is composed of power relay units, a master unit, a systems protection unit, and, in special instances, a reversing motor unit. The circuitry for the four basic units of this control system is explained in detail and shown in the schematics and photographs
Strong mass effect on ion beam mixing in metal bilayers
Molecular dynamics simulations have been used to study the mechanism of ion
beam mixing in metal bilayers. We are able to explain the ion induced
low-temperature phase stability and melting behavior of bilayers using only a
simple ballistic picture up to 10 keV ion energies. The atomic mass ratio of
the overlayer and the substrate constituents seems to be a key quantity in
understanding atomic mixing. The critical bilayer mass ratio of
is required for the occurrence of a thermal spike (local melting) with a
lifetime of ps at low-energy ion irradiation (1 keV) due to a
ballistic mechanism. The existing experimental data follow the same trend as
the simulated values.Comment: 4 pages, 4 figures, preprin
Pharmacology of DB844, an orally active aza analogue of pafuramidine, in a monkey model of second stage human African trypanosomiasis
Novel drugs to treat human African trypanosomiasis (HAT) are still urgently needed despite the recent addition of nifurtimox-eflornithine combination therapy (NECT) to WHO Model Lists of Essential Medicines against second stage HAT, where parasites have invaded the central nervous system (CNS). The pharmacology of a potential orally available lead compound, N-methoxy-6-{5-[4-(N-methoxyamidino) phenyl]-furan-2-yl}-nicotinamidine (DB844), was evaluated in a vervet monkey model of second stage HAT, following promising results in mice. DB844 was administered orally to vervet monkeys, beginning 28 days post infection (DPI) with Trypanosoma brucei rhodesiense KETRI 2537. DB844 was absorbed and converted to the active metabolite 6-[5-(4-phenylamidinophenyl)-furanyl-2-yl]-nicotinamide (DB820), exhibiting plasma C(max) values of 430 and 190 nM for DB844 and DB820, respectively, after the 14th dose at 6 mg/kg qd. A 100-fold reduction in blood trypanosome counts was observed within 24 h of the third dose and, at the end of treatment evaluation performed four days post the last drug dose, trypanosomes were not detected in the blood or cerebrospinal fluid of any monkey. However, some animals relapsed during the 300 days of post treatment monitoring, resulting in a cure rate of 3/8 (37.5%) and 3/7 (42.9%) for the 5 mg/kg×10 days and the 6 mg/kg×14 days dose regimens respectively. These DB844 efficacy data were an improvement compared with pentamidine and pafuramidine both of which were previously shown to be non-curative in this model of CNS stage HAT. These data show that synthesis of novel diamidines with improved activity against CNS-stage HAT was possible
Pasture Management in the US Midwest – An Assessment of Current Practices and Future Opportunities
Managed grazing offers significant potential to improve the sustainability of livestock farms in the US Midwest, however the benefits of managed grazing are largely influenced by the management practices employed on farm. The objective of this study was to gain an understanding of current grazing practices on Midwest farms and to identify the knowledge and support needs of graziers. A total of 185 responses were received from a range of different enterprises including dairy, beef, and sheep production. Results show a substantial degree of variation in grazing management practices between respondents and highlights significant scope for improvement on farms particularly in the areas of pasture measurement and budgeting, and grazing infrastructure. Reported benefits of managed grazing included lower environmental impact, better pasture and animal performance, better animal health and welfare, and lower costs. Challenges with managed grazing included time and labor input, maintaining pasture quantity and quality during the grazing season, adverse weather conditions such as excessive rain and drought, and animal health challenges such as heat stress, parasites and in some cases coyotes. The study highlighted opportunities for research and extension providers to better support farmers with information and advice and identified knowledge gaps in areas such as pasture species selection, soil fertility, grazing infrastructure, pasture budgeting, legumes, and pasture measurement. The study successfully gained an insight into graziers in the Midwest, the outputs of which, will be valuable to a number of key stakeholders going forward, including researchers, extension agents, farmers and policy makers
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Texas STATEMAP Program Summary, FY19 (2019–2020)
Five geologic maps have been completed at a 1:24,000 scale in four project areas with support from STATEMAP and the Bureau of Economic Geology's State of Texas Advanced Resource Recovery program (STARR). Three of these maps were on the Texas Coastal Plain, including one (the Lake Stephenson quadrangle) on the upper Texas Coastal Plain in the Galveston Bay area and two (the Bloomington and Olivia quadrangles) on the middle Texas Coastal Plain in the Matagorda Bay area.
These maps continue efforts to:
1. Better understand the evolution of the coastal plain in response to sea-level changes associated with numerous Quaternary glacial and interglacial cycles.
2. Develop more effective methods to map low-relief coastal deposits using high-resolution topographic maps produced from airborne lidar data and near-surface geophysical methods.
High-resolution topography and geophysical methods both aid in the identification of stratal units and their distribution in areas where exposures are poor or nonexistent.
Mineral-resource mapping produced one map (the Katemcy quadrangle) to extend recent mapping of an industrial sand resource area in central Texas. This map facilitates the development of mineral resources of the state, emphasizing those that will help meet the demand for industrial sand for hydraulic fracturing and construction. The detailed map can be used to evaluate and explore the mineral-resource potential of the area.
Mapping in the central Texas urban growth corridor northeast of Austin produced one map (the Taylor quadrangle) that extends previous mapping in this critical urban growth and transportation corridor. This map addresses the ongoing need for planning and managing groundwater, surface water, land use, and construction projects where rapid population growth and suburban development have caused an increased demand for water and earth resources.Bureau of Economic Geolog
Ab initio many-body calculations on infinite carbon and boron-nitrogen chains
In this paper we report first-principles calculations on the ground-state
electronic structure of two infinite one-dimensional systems: (a) a chain of
carbon atoms and (b) a chain of alternating boron and nitrogen atoms. Meanfield
results were obtained using the restricted Hartree-Fock approach, while the
many-body effects were taken into account by second-order M{\o}ller-Plesset
perturbation theory and the coupled-cluster approach. The calculations were
performed using 6-31 basis sets, including the d-type polarization
functions. Both at the Hartree-Fock (HF) and the correlated levels we find that
the infinite carbon chain exhibits bond alternation with alternating single and
triple bonds, while the boron-nitrogen chain exhibits equidistant bonds. In
addition, we also performed density-functional-theory-based local density
approximation (LDA) calculations on the infinite carbon chain using the same
basis set. Our LDA results, in contradiction to our HF and correlated results,
predict a very small bond alternation. Based upon our LDA results for the
carbon chain, which are in agreement with an earlier LDA calculation
calculation [ E.J. Bylaska, J.H. Weare, and R. Kawai, Phys. Rev. B 58, R7488
(1998).], we conclude that the LDA significantly underestimates Peierls
distortion. This emphasizes that the inclusion of many-particle effects is very
important for the correct description of Peierls distortion in one-dimensional
systems.Comment: 3 figures (included). To appear in Phys. Rev.
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