11,624 research outputs found
Laboratory studies of silicon vapor deposition, phase A
A system is described capable of carrying out silicon vapor deposition experiments in the low 10 to the minus 10th power torr vacuum range. The system was assembled and tested for use in a program aimed at exploration of vacuum heteroepitaxy of silicon on several substrates of potential interest for photovoltaic applications. An experiment is described in which a silicon layer 2.5 microns thick was deposited on a pyrolytically cleaned tungsten substrate held at a temperature of 400 C. Using a resistance heated silicon source, thicker layers can be deposited in periods of hours by utilizing closer source to substrate distances
Electromagnetic containerless processing requirements and recommended facility concept and capabilities for space lab
Containerless melting, reaction, and solidification experiments and processes which potentially can lead to new understanding of material science and production of new or improved materials in the weightless space environment are reviewed in terms of planning for spacelab. Most of the experiments and processes discussed are amenable to the employment of electromagnetic position control and electromagnetic induction or electron beam heating and melting. The spectrum of relevant properties of materials, which determine requirements for a space laboratory electromagnetic containerless processing facility are reviewed. Appropriate distributions and associated coil structures are analyzed and compared on the basis of efficiency, for providing the functions of position sensing, control, and induction heating. Several coil systems are found capable of providing these functions. Exchangeable modular coils in appropriate sizes are recommended to achieve the maximum power efficiencies, for a wide range of specimen sizes and resistivities, in order to conserve total facility power
From Instantons to Sphalerons: Time-Dependent Periodic Solutions of SU(2)-Higgs Theory
We solve numerically for periodic, spherically symmetric, classical solutions
of SU(2)-Higgs theory in four-dimensional Euclidean space. In the limit of
short periods the solutions approach tiny instanton-anti-instanton
superpositions while, for longer periods, the solutions merge with the static
sphaleron. A previously predicted bifurcation point, where two branches of
periodic solutions meet, appears for Higgs boson masses larger than .Comment: 14 pages, RevTeX with eps figure
Performance of AAOmega: the AAT multi-purpose fibre-fed spectrograph
AAOmega is the new spectrograph for the 2dF fibre-positioning system on the
Anglo-Australian Telescope. It is a bench-mounted, double-beamed design, using
volume phase holographic (VPH) gratings and articulating cameras. It is fed by
392 fibres from either of the two 2dF field plates, or by the 512 fibre SPIRAL
integral field unit (IFU) at Cassegrain focus. Wavelength coverage is 370 to
950nm and spectral resolution 1,000-8,000 in multi-Object mode, or 1,500-10,000
in IFU mode. Multi-object mode was commissioned in January 2006 and the IFU
system will be commissioned in June 2006.
The spectrograph is located off the telescope in a thermally isolated room
and the 2dF fibres have been replaced by new 38m broadband fibres. Despite the
increased fibre length, we have achieved a large increase in throughput by use
of VPH gratings, more efficient coatings and new detectors - amounting to a
factor of at least 2 in the red. The number of spectral resolution elements and
the maximum resolution are both more than doubled, and the stability is an
order of magnitude better.
The spectrograph comprises: an f/3.15 Schmidt collimator, incorporating a
dichroic beam-splitter; interchangeable VPH gratings; and articulating red and
blue f/1.3 Schmidt cameras. Pupil size is 190mm, determined by the competing
demands of cost, obstruction losses, and maximum resolution. A full suite of
VPH gratings has been provided to cover resolutions 1,000 to 7,500, and up to
10,000 at particular wavelengths.Comment: 13 pages, 4 figures; presented at SPIE, Astronomical Telescopes and
Instrumentation, 24 - 31 May 2006, Orlando, Florida US
Chemical Weed Control in Crops
This publication provides a diagram showing the stages of growth in small grain and a table with crop varieties, weeds, safest time to spray, chemical, and rate information. Recommendations for the quantity of herbicide required to control various weed species and calculating the amount of chemical to apply per acre are also included
Increasing hospitalization and death possibly due to Clostridium difficile diarrheal disease.
This study calculated yearly estimated national hospital discharge (1985 to 1994) and age-adjusted death rates (1980 to 1992) due to bacterial, viral, protozoal, and ill-defined enteric pathogens. Infant and young child hospitalization (but not death) rates in each category increased more than 50% during 1990 to 1994. Age-adjusted death and hospitalization rates due to enteric bacterial infections and hospitalizations due to enteric viral infections have increased since 1988. The increases in hospitalization and death rates from enteric bacterial infections were due to a more than eightfold increase in rates for specified enteric bacterial infections that were uncoded during this period (ICD9 00849). To identify bacterial agents responsible for most of these infections, hospital discharges and outpatient claims (coded with more detail after 1992) were examined for New Mexico's Lovelace Health Systems for 1993 to 1996. Of diseases due to uncoded enteric pathogens, 73% were due to Clostridium difficile infection. Also, 88% of Washington State death certificates (1985 to 1996) coded to unspecified enteric pathogen infections (ICD0084) listed C. difficile infection
Investigation of the preparation of materials in space. Task 4 - Field management for weightless containerless processing Quarterly progress report, 22 Aug. - 31 Oct. 1969
Weightless containerless processing for space, electromagnetic position control, force measurements and techniques, and hydrodynamic
Weed Control in Corn
This publication provides recommendations for using cultivation such as a rotary hoe or flextine harrow to control weeds in corn, as well as the costs of these methods. Guidance is also included for chemical control with 2,4-D, atrazine, atrazine plus linuron, Ramrod, CDAA and CDAA-T, as well as information on pre-emergence spraying, directed sprays, herbicide-insecticide-fertilizer mixes, and the estimated cost of herbicide treatment
Control and Elimination of Field Bindweed
This publication provides information on various methods to control creeping jenny or field bindweed in fields. Reducing stands with combinations of cultivation, cropping, and chemicals is discussed, as well as recommendations to prevent spreading, using nonselective herbicides, and reducing stands in shelterbelts
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