4,263 research outputs found
Evaluation criteria for commercially oriented materials processing in space proposals
An approach and criteria for evaluating NASA funded experiments and demonstrations which have commercial potential were developed. Methods for insuring quick initial screening of commercial proposals are presented. Recommendations are given for modifying the current evaluation approach. New criteria for evaluating commercially orientated materials processing in space (MPS) proposals are introduced. The process for selection of qualified individuals to evaluate the phases of this approach and criteria is considered and guidelines are set for its implementation
Odonata at a Small Woodland Pond in Southern Illinois
A survey of the adult odonate fauna of a small woodland pond in Pope County, Illinois, was conducted during 1983--·1984. Twenty-four species were collected including Aeshna mutata and Anax longipes. In addition, Libellula vibrans was collected in 1982, and Aeshna sp. (probably u. umbrosa) observed the same year but not collected
The X-ray binary population in M33: II. X-ray spectra and variability
In this paper we investigate the X-ray spectra and X-ray spectral variability
of compact X-ray sources for 3 Chandra observations of the Local Group galaxy
M33. The observations are centered on the nucleus and the star forming region
NGC 604. In the observations 261 sources have been detected. For a total of 43
sources the number of net counts is above 100, sufficient for a more detailed
spectral fitting. Of these sources, 25 have been observed in more than one
observation, allowing the study of spectral variability on ~months timescales.
A quarter of the sources are found to be variable between observations.
However, except for two foreground sources, no source is variable within any
observation above the 99% confidence level. Only six sources show significant
spectral variability between observations. A comparison of N_H values with HI
observations shows that X-ray absorption values are consistent with Galactic
X-ray binaries and most sources in M33 are intrinsically absorbed. The pattern
of variability and the spectral parameters of these sources are consistent with
the M33 X-ray source population being dominated by X-ray binaries: Two thirds
of the 43 bright sources have spectral and timing properties consistent with
X-ray binaries; we also find two candidates for super-soft sources and two
candidates for quasi-soft sources.Comment: 25 pages, ApJ accepte
Soil Aggregate Dynamics, Particulate Organic Matter and Phosphate under Dryland and Irrigated Pasture
Soil aggregate formation and turnover affects the rate of occlusion or release of soil organic matter and therefore the availability for mineralisation or stabilisation of soil carbon (C) and phosphorus (P). Furthermore, differences in soil type, management and the quantity and quality of organic inputs can affect aggregate turnover rates (Six et al., 2000). Under pastoral farming the ratio of coarse particulate organic matter (inter-POM) inside macroaggregates but outside microaggregates to fine POM (intra-POM) within microaggregates may provide an indication of physical processes influencing mineralisation and stabilisation of soil C and organic P (Po). Our aim was to determine the coarse and fine POM and associated C and P contents in water stable macro and microaggregates under long term irrigated and dryland pasture grazed by sheep
How Reasoning Aims at Truth
Many hold that theoretical reasoning aims at truth. In this paper, I ask what it is for reasoning to be thus aim-directed. Standard answers to this question explain reasoning’s aim-directedness in terms of intentions, dispositions, or rule-following. I argue that, while these views contain important insights, they are not satisfactory. As an alternative, I introduce and defend a novel account: reasoning aims at truth in virtue of being the exercise of a distinctive kind of cognitive power, one that, unlike ordinary dispositions, is capable of fully explaining its own exercises. I argue that this account is able to avoid the difficulties plaguing standard accounts of the relevant sort of mental teleology
Spread super for cereal crops
THE use of bulk superphosphate broadcast direct on to the paddocks is a new method of reducing fertiliser costs.
But it has long been known that broadcasting phosphate is less efficient than drilling it in with the seed.
The experiment reported here was designed to demonstrate this point
Stellar-Mass Black Holes in the Solar Neighborhood
We search for nearby, isolated, accreting, ``stellar-mass'' (3 to
) black holes. Models suggest a synchrotron spectrum in visible
wavelengths and some emission in X-ray wavelengths. Of 3.7 million objects in
the Sloan Digital Sky Survey Early Data Release, about 150,000 objects have
colors and properties consistent with such a spectrum, and 87 of these objects
are X-ray sources from the ROSAT All Sky Survey. Thirty-two of these have been
confirmed not to be black-holes using optical spectra. We give the positions
and colors of these 55 black-hole candidates, and quantitatively rank them on
their likelihood to be black holes. We discuss uncertainties the expected
number of sources, and the contribution of blackholes to local dark matter.Comment: Replaced with version accepted by ApJ. 40 pages, 8 figure
Cereal, pasture legume and water supply prospects at Forrestania : results of experimental work east of Hyden, Western Australia
The agricultural potential of the Forrestania area appears at least equal to that of much of the settled eastern wheatbelt. The scrubplain soils of the Forrestania area have an average yield potential of at least 1 000 kg/ha wheat and carrying capacity of 1.8 to 3.7 sheep per hectare on improved pastures. The use of clover ley rotations would maintain these levels of potential yield. Partial crop failures caused by adverse seasonal conditions could be expected 10 years in every 100
On Exchange of Orbital Angular Momentum Between Twisted Photons and Atomic Electrons
We obtain an expression for the matrix element for a twisted
(Laguerre-Gaussian profile) photon scattering from a hydrogen atom. We consider
photons incoming with an orbital angular momentum (OAM) of ,
carried by a factor of not present in a plane-wave or pure
Gaussian profile beam. The nature of the transfer of units of OAM from
the photon to the azimuthal atomic quantum number of the atom is investigated.
We obtain simple formulae for these OAM flip transitions for elastic forward
scattering of twisted photons when the photon wavelength is large
compared with the atomic target size , and small compared the Rayleigh range
, which characterizes the collimation length of the twisted photon beam.Comment: 16 page
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