20,752 research outputs found
Ultraviolet spectroscopy of old novae and symbiotic stars
The IUE spectra are presented for two old novae and for two of the symbiotic variables. Prominent emission line spectra are revealed as a continuum whose appearance is effected by the system inclination. These data provide evidence for hot companions in the symbiotic stars, making plausible the binary model for these peculiar stars. Recent IUE spectra of dwarf novae provide additional support for the existence of optically thick accretion disks in active binary systems. The ultraviolet data of the eclipsing dwarf novae EX Hya and BV Cen appear flatter than for the noneclipsing systems, an effect which could be ascribed to the system inclination
U.S. Corn Producer’s Response to Increased Energy Prices: Evidence from Producer Surveys in 2001 and 2005
Crop Production/Industries, Risk and Uncertainty,
Demonstration of a sterilizable solid rocket motor system
A solid propellant rocket motor containing 60.9 Kg (134-lb) of propellant was successfully static fired after being subjected to eight heat sterilization cycles (three 54-hour cycles plus five 40-hour cycles) at 125 C (257 F). The test motor, a modified SVM-3 chamber, incorporated a flexible grain retention system of EPR rubber to relieve thermal shrinkage stresses. The propellant used in the motor was ANB-3438, and 84 wt% solids system (18 wt% aluminum) containing 66 wt% stabilized ammonium perchlorate oxidizer and a saturated hydroxylterminated polybutadiene binder. Bonding of the propellant to the EPR insulation (GenGard V-4030) was provided by the use of SD-886, an epoxy urethane restriction
Drive mechanism for production of simulated human breath
Simulated breath drive mechanism was developed as subsystem to breathing metabolic simulator. Mechanism reproduces complete range of human breath rate, breath depth, and breath waveform, as well as independently controlled functional residual capacity. Mechanism was found capable of simulating various individual human breathing characteristics without any changes of parts
The Interstellar Rubidium Isotope Ratio toward Rho Ophiuchi A
The isotope ratio, 85Rb/87Rb, places constraints on models of the
nucleosynthesis of heavy elements, but there is no precise determination of the
ratio for material beyond the Solar System. We report the first measurement of
the interstellar Rb isotope ratio. Our measurement of the Rb I line at 7800 A
for the diffuse gas toward rho Oph A yields a value of 1.21 +/- 0.30 (1-sigma)
that differs significantly from the meteoritic value of 2.59. The Rb/K
elemental abundance ratio for the cloud also is lower than that seen in
meteorites. Comparison of the 85Rb/K and 87Rb/K ratios with meteoritic values
indicates that the interstellar 85Rb abundance in this direction is lower than
the Solar System abundance. We attribute the lower abundance to a reduced
contribution from the r-process. Interstellar abundances for Kr, Cd, and Sn are
consistent with much less r-process synthesis for the solar neighborhood
compared to the amount inferred for the Solar System.Comment: 12 pages with 2 figures and 1 table; will appear in ApJ Letter
Analysis of the spatial distribution of organic farming in the Provence-Alpes-Côte d’Azur (PACA) region of France: building a methodology for observation and prospective
Analysis of the distribution of organic farming and its determinants is a major challenge for the construction of scenarios related to the evolution of organic farming that take the set of factors that limit or facilitate conversions and their sustainability into account. In order to support different development scenarios for organic farming in view of environmental and marketing challenges, an econometric and geostatistic study was initiated in the PACA region. The approach consists of three stages. The first stage involves the construction, over a 20-year period, of a longitudinal spatial database concerning certified organic producers and distributors. This database is georeferenced at the plot level. It will then be necessary to statistically analyse the trends and the determinants of the organic farming distribution process over time and space. Finally, this knowledge will be used to build scenarios for the development of organic farming production on the medium term. Intermediary results presented within this framework well be based on the georeferencing of producers and distributors at the community level in 2007, without drawing on farm data issued by the MRA (French farmers mutual insurance system), and on the results of an exhaustive survey of all organic distributors implemented in 2008 in the PACA region
High-Resolution Measurements of Intersystem Bands of Carbon Monoxide toward X Persei
In an echelle spectrum of X Per acquired with the Space Telescope Imaging
Spectrograph we have identified individual rotational lines of 11
triplet-singlet (intersystem) absorption bands of ^12CO. Four bands provide
first detections for interstellar clouds. From a comparison with the zeta Oph
sight line we find that X Per is obscured by a higher 12CO column density of
1.4 x 10^16 cm-2. Together with the high spectral resolution of 1.3 km s-1,
this allows (i) an improved measurement of previously published f-values for
seven bands, and (ii) an extraction of the first astrophysical oscillator
strengths for d-X (8-0), (9-0), and (10-0), as well as for e-X (12-0). The
^13CO d-X (12-0) band, previously suspected to exist toward zeta Oph, is now
readily resolved and modeled. Our derived intersystem f-values for ^12CO
include a few mild (leq 34%) disagreements with recent predictions from a
perturbation analysis calculated for the interstellar excitation temperature.
Overall, the comparison confirms the superiority of employing multiple singlet
levels in the calculations of mixing coefficients over previous single-level
predictions.Comment: 11 pages (incl. 1 figure). Accepted by ApJ Letter
Relationships between different nutritional anthropometric statuses and health-related fitness of South African primary school children
Background A double burden of both under- and over-nutrition exists among South African children. Aim Describe associations between nutritional statuses and health-related fitness test performances. Subjects and methods Height and weight of 10 285 children (6-13 years; n=5604 boys and 4681 girls) were measured and used to calculate: body mass index (BMI), and prevalence of overweight and obesity, stunting, wasting, and underweight. Physical fitness scores for standing long jump, shuttle run, sit-and-reach, sit-up (EUROFIT) and cricket ball throw were assessed. Age and gender specific z-scores were calculated for these variables. Physical fitness for each nutritional status group was compared to children of normal weight. Results Compared to normal weight children, overweight and obese children scored lower on all fitness tests (p<.001), except cricket ball throw (p=.235) and sit-and-reach (p=.015). Stunted and underweight children performed poorer than normal weight children on most fitness tests (p<.001), except sit-and-reach (stunted: p=.829; underweight: p=.538) and shuttle run (underweight: p=.017). Performance of wasted children was not as highly compromised as other undernourished groups, but they performed poorer on the cricket ball throw (p<.001). Conclusions When compared to normal weight children, both under- and over-nourished children performed poorer on some, but not all, health-related fitness tests
Information on nutritional supplement labels: time for legislation?
Background: Nutritional supplements have received attention both from food manufacturers, as a means of marketing the added value to health; and from consumers, in terms of awareness, education, and improved health. To assist this process, it is important to have specific knowledge and understanding of the claims made on labels of nutritional supplement products used for general, and more specifically, for sports consumers. The industry is not regulated, and therefore the claims that are made may not always be accurate.Method: The aim was to describe the labelling and claims information on the labels of a select group of nutritional supplements, either manufactured in, or imported into South Africa. Specific predetermined categories of labelling and claims made on the containers were assessed and summarised.Results: Forty products were selected for analysis, of which 21 (53%) were locally assembled or manufactured products, and 19 (48%), international imported products. Ninety-five per cent of products contained a warning statement on the label. Eighty-five per cent of the nutritional supplement products had a disclaimer on the label. Ninety-eight per cent of the nutritional supplement product labels included some claim on the label.Conclusion: The following information, in particular, needs to be regulated and enforced as part of the labelling process, to ensure that the consumer can make an informed choice. This includes highlighting the potential for adverse events, encouraging warning statements pertaining to “exclusion of use, and “not a cure for disease states”, and alerting consumers of the potential for the presence of banned substances, based on laboratory screen methods.Keywords: nutritional, supplements, contaminants, claims, legislation, labellin
Intraband electron focusing in bilayer graphene
We propose an implementation of a valley selective electronic Veselago lens
in bilayer graphene. We demonstrate that in the presence of an appropriately
oriented potential step, low-energy electrons radiating from a point source can
be re-focused coherently within the same band. The phenomenon is due to the
trigonal warping of the band structure that leads to a negative refraction
index. We show that the interference pattern can be controlled by an external
mechanical strain.Comment: 14 pages, 8 figure
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