12,648 research outputs found
Evaluating the Dynamic Nature of Market Risk
This study examines the systematic risk present in major crops for the United States and three corn-belt states. An index of commodities is used in conjunction with cash receipts to generate dynamic estimates of the systematic risk for each crop and state. In our study, we find that beta estimates from a time varying parameter model (FLS) and OLS formulation are substantially different. From our graphs of betas over time, one gains insight into the changing nature of risk and the impact of institutional and macroeconomic events. Systematic risk is shown to increase for most crops over the analyzed period with significant changes in volatility after the collapse of the Bretton Woods Accord.Systematic risk, flexible least squares, single index model, farm policy, macroeconomics, Agribusiness, Agricultural Finance, Consumer/Household Economics, Demand and Price Analysis, Farm Management, Financial Economics, Institutional and Behavioral Economics, Marketing, Risk and Uncertainty,
Extracting text from PostScript
We show how to extract plain text from PostScript files. A textual scan is inadequate because PostScript interpreters can generate characters on the page that do not appear in the source file. Furthermore, word and line breaks are implicit in the graphical rendition, and must be inferred from the positioning of word fragments. We present a robust technique for extracting text and recognizing words and paragraphs. The method uses a standard PostScript interpreter but redefines several PostScript operators, and simple heuristics are employed to locate word and line breaks. The scheme has been used to create a full-text index, and plain-text versions, of 40,000 technical reports (34 Gbyte of PostScript). Other text-extraction systems are reviewed: none offer the same combination of robustness and simplicity
Development of composite ionizer materials final report
Composite ionizer materials - effect of secondary additions to tungsten powder on sintering mechanisms and heat stability of porous structure
Development and testing of porous ionizer materials, part I Summary report, Feb. 1965 - May 1966
Development and testing of porous tungsten ionizer materials for cesium contact engine
Astrometric Discovery of GJ 164B
We discovered a low-mass companion to the M-dwarf GJ 164 with the CCD-based
imaging system of the Stellar Planet Survey (STEPS) astrometric program. The
existence of GJ 164B was confirmed with Hubble Space Telescope NICMOS imaging
observations. A high-dispersion spectral observation in V sets a lower limit of
delta m> 2.2 mag between the two components of the system. Based upon our
parallax value of 0.082 +/- 0.008, we derive the following orbital parameters:
P = 2.04 +/- 0.03 y, a = 1.03 +/- 0.03 AU, and Mtotal = 0.265 +/- 0.020 MSun.
The component masses are MA = 0.170 +/- 0.015 MSun and MB = 0.095 +/- 0.015
MSun. Based on its mass, colors, and spectral properties, GJ 164B has spectral
type M6-8 V.Comment: pdf file 14 pages with 6 fig
Weak measurements are universal
It is well known that any projective measurement can be decomposed into a
sequence of weak measurements, which cause only small changes to the state.
Similar constructions for generalized measurements, however, have relied on the
use of an ancilla system. We show that any generalized measurement can be
decomposed into a sequence of weak measurements without the use of an ancilla,
and give an explicit construction for these weak measurements. The measurement
procedure has the structure of a random walk along a curve in state space, with
the measurement ending when one of the end points is reached. This shows that
any measurement can be generated by weak measurements, and hence that weak
measurements are universal. This may have important applications to the theory
of entanglement.Comment: 4 pages, RevTeX format, essentially the published version, reference
update
Gaussian approximation and single-spin measurement in OSCAR MRFM with spin noise
A promising technique for measuring single electron spins is magnetic
resonance force microscopy (MRFM), in which a microcantilever with a permanent
magnetic tip is resonantly driven by a single oscillating spin. If the quality
factor of the cantilever is high enough, this signal will be amplified over
time to the point that it can be detected by optical or other techniques. An
important requirement, however, is that this measurement process occur on a
time scale short compared to any noise which disturbs the orientation of the
measured spin. We describe a model of spin noise for the MRFM system, and show
how this noise is transformed to become time-dependent in going to the usual
rotating frame. We simplify the description of the cantilever-spin system by
approximating the cantilever wavefunction as a Gaussian wavepacket, and show
that the resulting approximation closely matches the full quantum behavior. We
then examine the problem of detecting the signal for a cantilever with thermal
noise and spin with spin noise, deriving a condition for this to be a useful
measurement.Comment: 12 pages, 8 figures in EPS format, RevTeX 4.
ORIENTATION BY BULK MESSENGER SENSORS IN AQUATIC VERTEBRATES
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72353/1/j.1749-6632.1969.tb13050.x.pd
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