26,916 research outputs found
BeppoSAX observations of the quasar Markarian 205
We present the first BeppoSAX observation (0.1 to 220 keV) of the quasar Mrk
205. We have searched for the unusual Fe line profile claimed in the XMM-Newton
spectrum which has been widely discussed in recent literature. We find no
evidence for a broad, ionized Fe line component in our data. We detect for the
first time a Compton hump in this object. Besides, when this component is
included in the fit, the line strength diminishes, in agreement with a recent
re-analysis of the XMM-Newton data, but with better constraints on the
reflection component thanks to the PDS instrument (15-220 keV). We interpret
this fact as another indication for illumination of a distant and cold material
rather than reprocessing in the highly ionized inner parts of an accretion
disk. We cannot constrain the presence of a high energy cutoff but we confirm
the existence of a variable soft excess (one year timescale).Comment: 13 pages, 12 figures, accepted for publication in A&
Characteristics of Postural Muscle Activity in Response to A Motor-Motor Task in Elderly
The purpose of the current study was to evaluate postural muscle performance of older adults in response to a combination of two motor tasks perturbations. Fifteen older participants were instructed to perform a pushing task as an upper limb perturbation while standing on a fixed or sliding board as a lower limb perturbation. Postural responses were characterized by onsets and magnitudes of muscle activities as well as onsets of segment movements. (Please see full abstract article
Integrating with Their Feet: Cross-Border Lending at the German-Austrian Border
The current economic policy discussion on financial integration in the European Union concentrates on cross-border mergers. We study the impact of cross-border lending in a theoretical model where banks acquire either hard or soft information on borrowing firms and predict that the closer firms are to the border the more likely banks are to offer them cross-border loans. This hypothesis is confirmed in the ifo Business Climate Survey that reports the perceptions of German firms on banks lending behavior between 2003 and 2006. In contrast to the policy of harmonization, differences in bank regulations may provide incentives for cross-border lending. Thus, we show that financial integration may take place from the bottom up
A Survey of the Northern Sky for TeV Point Sources
A search for steady TeV point sources anywhere in the northern sky has been
made with data from the Milagrito air-shower-particle detector. Over 3 x 10**9
events collected from 1997 February to 1998 May have been used in this study.
No statistically significant excess above the background from the isotropic
flux of cosmic rays was found for any direction of the sky with declination
between -5 degrees and 71.7 degrees. Upper limits are derived for the photon
flux above 1 TeV from any steady point source in the northern sky.Comment: 2 Figure
Toward a Clean Sample of Ultra-Luminous X-ray Sources
CONTEXT. Observational follow-up programmes for the characterization of
ultra-luminous X-ray sources (ULXs) require the construction of clean samples
of such sources in which the contamination by foreground/background sources is
minimum.
AIMS. In this article we calculate the degree of foreground/background
contaminants among the ULX sample candidates in the Colbert & Ptak (2002)
catalogue and compare these computations with available spectroscopical
identifications.
METHODS. We use statistics based on known densities of X-ray sources and
AGN/QSOs selected in the optical. The analysis is done individually for each
parent galaxy. The existing identifications of the optical counterparts are
compiled from the literature.
RESULTS. More than a half of the ULXs, within twice the distance of the major
axis of the 25 mag/arcsec isophote from RC3 nearby galaxies and with X-ray
luminosities [2-10 keV] erg/s, are expected to be high
redshift background QSOs. A list of 25 objects (clean sample) confirmed to be
real ULXs or to have a low probability of being contaminant
foreground/background objects is provided.Comment: 9 pages, accepted in A&
Arkansas Corn and Grain Sorghum Peformance Tests 2017
Corn and grain sorghum performance tests are conducted each year in Arkansas by the University of Arkansas System Division of Agriculture. The tests provide information to companies marketing seed within the state, and aid the Arkansas Cooperative Extension Service in formulating recommendations for producers
Simultaneous Arithmetic Progressions on Algebraic Curves
A simultaneous arithmetic progression (s.a.p.) of length k consists of k
points (x_i, y_\sigma(i)), where x_i and y_i are arithmetic progressions and
\sigma is a permutation. Garcia-Selfa and Tornero asked whether there is a
bound on the length of an s.a.p. on an elliptic curve in Weierstrass form over
Q. We show that 4319 is such a bound for curves over R. This is done by
considering translates of the curve in a grid as a graph. A simple upper bound
is found for the number of crossings and the 'crossing inequality' gives a
lower bound. Together these bound the length of an s.a.p. on the curve. We then
use a similar method to extend the result to arbitrary real algebraic curves.
Instead of considering s.a.p.'s we consider k^2/3 points in a grid. The number
of crossings is bounded by Bezout's Theorem. We then give another proof using a
result of Jarnik bounding the number of grid points on a convex curve. This
result applies as any real algebraic curve can be broken up into convex and
concave parts, the number of which depend on the degree. Lastly, these results
are extended to complex algebraic curves.Comment: 11 pages, 6 figures, order of email addresses corrected 12 pages,
closing remarks, a reference and an acknowledgment adde
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