5,562 research outputs found
On Vague Computers
Vagueness is something everyone is familiar with. In fact, most people think
that vagueness is closely related to language and exists only there. However,
vagueness is a property of the physical world. Quantum computers harness
superposition and entanglement to perform their computational tasks. Both
superposition and entanglement are vague processes. Thus quantum computers,
which process exact data without "exploiting" vagueness, are actually vague
computers
The Community Reinvestment Act: Its Impact on Lending in Low-Income Communities in the United States
This paper reviews data and research studies that demonstrate that CRA has helped to increase lending to low-income borrowers and in low-income neighborhoods, and that expanded CRA lending has been accomplished while maintaining sound lending practices and bank profitability. The paper also discusses literature that draws alternative conclusions, as well as studies that find, despite increases in lending and banking services to low- and moderate-income areas and to minority borrowers, that disparities still exist between the services afforded to these communities and those offered to the market as a whole
Long term X-ray spectral variability of the nucleus of M81
We have analysed the soft X-ray emission from the nuclear source of the
nearby spiral galaxy M81, using the available data collected with ROSAT, ASCA,
BeppoSAX and Chandra. The source flux is highly variable, showing (sometimes
dramatic: a factor of 4 in 20 days) variability at different timescales, from 2
days to 4 years, and in particular a steady increase of the flux by a factor of
>~ 2 over 4 years, broken by rapid flares. After accounting for the extended
component resolved by Chandra, the nuclear soft X-ray spectrum (from
ROSAT/PSPC, BeppoSAX/LECS and Chandra data) cannot be fitted well with a single
absorbed power-law model. Acceptable fits are obtained adding an extra
component, either a multi-color black body (MCBB) or an absorption feature. In
the MCBB case the inner accretion disk would be far smaller than the
Schwartzchild radius for the 3-60X 10^6 solar masses nucleus requiring a
strictly edge-on inclination of the disk, even if the nucleus is a rotating
Kerr black hole. The temperature is 0.27 keV, larger than expected from the
accretion disk of a Schwartzchild black hole, but consistent with that expected
from a Kerr black hole. In the power-law + absorption feature model we have
either high velocity (0.3 c) infalling C_v clouds or neutral C_i absorption at
rest. In both cases the C:O overabundance is a factor of 10.Comment: 30 pages with 15 figures. Accepted for publication in the
Astrophysical Journa
The Faber-Jackson relation for early-type galaxies: Dependence on the magnitude range
We take a sample of early-type galaxies from the Sloan Digital Sky Survey
(SDSS-DR7, 90 000 galaxies) spanning a range of approximately 7 in
both and filters and analyse the behaviour of the Faber-Jackson
relation parameters as functions of the magnitude range. We calculate the
parameters in two ways: i) We consider the faintest (brightest) galaxies in
each sample and we progressively increase the width of the magnitude interval
by inclusion of the brighter (fainter) galaxies
(increasing-magnitude-intervals), and ii) we consider narrow-magnitude
intervals of the same width ( ) over the whole magnitude
range available (narrow-magnitude-intervals). Our main results are that: i) in
both increasing and narrow-magnitude-intervals the Faber-Jackson relation
parameters change systematically, ii) non-parametric tests show that the
fluctuations in the values of the slope of the Faber-Jackson relation are not
products of chance variations. We conclude that the values of the Faber-Jackson
relation parameters depend on the width of the magnitude range and the
luminosity of galaxies within the magnitude range. This dependence is caused,
to a great extent by the selection effects and because the geometrical shape of
the distribution of galaxies on the plane depends on
luminosity. We therefore emphasize that if the luminosity of galaxies or the
width of the magnitude range or both are not taken into consideration when
comparing the structural relations of galaxy samples for different wavelengths,
environments, redshifts and luminosities, any differences found may be
misinterpreted.Comment: 15 pages, 5 figures. A&A. Accepte
Natural Quintessence?
We formulate conditions for the naturalness of cosmological quintessence
scenarios. The quintessence lagrangian is taken to be the sum of a simple
exponential potential and a non-canonical kinetic term. This parameterization
covers most variants of quintessence and makes the naturalness conditions
particularly transparent. Several ``natural'' scalar models lead, for the
present cosmological era, to a large fraction of homogeneous dark energy
density and an acceleration of the scale factor as suggested by observation.Comment: 11 pages LaTeX, 3 figures included, numerical correctio
Spectral optical monitoring of 3C390.3 in 1995-2007: I. Light curves and flux variation of the continuum and broad lines
Here we present the results of the long-term (1995-2007) spectral monitoring
of the broad line radio galaxy \object{3C~390.3}, a well known AGN with the
double peaked broad emission lines, usually assumed to be emitted from an
accretion disk. To explore dimensions and structure of the BLR, we analyze the
light curves of the broad H and H line fluxes and the continuum
flux. In order to find changes in the BLR, we analyze the H and
H line profiles, as well as the change in the line profiles during the
monitoring period. First we try to find a periodicity in the continuum and
H light curves, finding that there is a good chance for quasi-periodical
oscillations. Using the line shapes and their characteristics (as e.g. peaks
separation and their intensity ratio, or FWHM) of broad H and H
lines, we discuss the structure of the BLR. Also, we cross-correlate the
continuum flux with H and H lines to find dimensions of the BLR.
We found that during the monitoring period the broad emission component of the
H and H lines, and the continuum flux varied by a factor of
4-5. Also, we detected different structure in the line profiles of
H and H. It seems that an additional central component is
present and superposed to the disk emission. In the period of high activity
(after 2002), H became broader than H and red wing of H
was higher than the one of H. We found time lags of 95 days
between the continuum and H flux, and about 120 days between the
continuum and H flux. Variation in the line profiles, as well as
correlation between the line and continuum flux during the monitoring period is
in the favor of the disk origin of the broad lines with the possible
contribution of some additional region and/or some kind of perturbation in the
disk.Comment: 32 pages, accepted to A&A, typos correcte
The influence of kinematic conditions and design on the wear of patella-femoral replacements
The success rate of patella-femoral arthroplasty varies between 44% and 90% in 17 years of follow-up. Several studies have been performed previously for assessing the surface wear in the patella-femoral joint. However, they have not included all six degrees of freedom. The aim of this study was to develop a six-axis patella-femoral joint simulator to assess the wear rate for two patellae designs (round and oval dome) at different kinematic conditions. An increase in patellar rotation from 1° to 4° led to a significantly (p0.08). The increase in wear rate was likely due to the higher cross shear. A decrease in patellar medial lateral displacement from passive to constrained resulted in a nonsignificant reduction in wear (p>0.06). There was no significant difference in wear rate between the two patellae designs (p>0.28). The volumetric wear under all conditions was positively correlated with the level of passive patellar tilt (rho>0.8). This is the first report of preclinical wear simulation of patella-femoral joint in a six-axis simulator under different kinematic conditions
Inflation at the Electroweak Scale
We present a simple model for slow-rollover inflation where the vacuum energy
that drives inflation is of the order of ; unlike most models, the
conversion of vacuum energy to radiation (``reheating'') is moderately
efficient. The scalar field responsible for inflation is a standard-model
singlet, develops a vacuum expectation value of the order of 4\times
10^6\GeV, has a mass of order 1\GeV, and can play a role in electroweak
phenomena.Comment: 14 page
XMM-Newton X-ray spectroscopy of the high-mass X-ray binary 4U1700-37 at low flux
We present results of a monitoring campaign of the high-mass X-ray binary
system 4U 1700-37/HD 153919, carried out with XMM-Newton in February 2001. The
system was observed at four orbital phase intervals, covering 37% of one
3.41-day orbit. The lightcurve includes strong flares, commonly observed in
this source. We focus on three epochs in which the data are not affected by
photon pile up: the eclipse, the eclipse egress and a low-flux interval in the
lightcurve around orbital phase phi ~0.25. The high-energy part of the
continuum is modelled as a direct plus a scattered component, each represented
by a power law with identical photon index (alpha ~1.4), but with different
absorption columns. We show that during the low-flux interval the continuum is
strongly reduced, probably due to a reduction of the accretion rate onto the
compact object. A soft excess is detected in all spectra, consistent with
either another continuum component originating in the outskirts of the system
or a blend of emission lines. Many fluorescence emission lines from
near-neutral species and discrete recombination lines from He- and H-like
species are detected during eclipse and egress. The detection of recombination
lines during eclipse indicates the presence of an extended ionised region
surrounding the compact object. The observed increase in strength of some
emission lines corresponding to higher values of the ionisation parameter xi
further substantiates this conclusion.Comment: 15 pages, 7 figures, accepted for publication in Astronomy and
Astrophysic
When the sad past is left: the mental metaphors between time, valence, and space
The Supplementary Material for this article can be found
online at: https://www.frontiersin.org/articles/10.3389/fpsyg.
2018.01019/full#supplementary-materialA mental metaphor is a strategy that consists of completing the representation of
a concept with structural components of a correlating concept. Three issues were
addressed here to deepen our understanding of this mechanism: the use of mental
metaphors between abstract concepts, the simultaneous activation of multiple mental
metaphors and the importance of the focus of attention on the relevant dimensions of a
mental metaphor. In two experiments, participants made temporal or valence judgments
(with their left or right hand) on verbs with a negative or positive meaning and conjugated
in the past or future form, allowing for the simultaneous activation of the “time is space”,
“valence is space,” and “time is valence” mental metaphors. Left-past/right-future and
left-negative/right-positive congruency effects were found, and these effects were greater
in the temporal and valence judgment tasks, respectively, demonstrating the importance
of attentional cuing. Simultaneously, a congruency effect between the abstract concepts
of time and valence (past-negative/future-positive) was observed, revealing that a mental
metaphor can occur between abstract concepts and that multiple metaphors can be
processed simultaneously. These results are discussed in terms of different theories
within the field of mental metaphors.MO was supported by a
Juan de la Cierva fellowship (JCI-2012-13046) from the Spanish
Ministry of Education and Science. Research was funded by
research projects PSI2012-32464 (Spanish Ministry of Economy
and Competitiveness) and PSI2015-67531-P (Spanish Ministry of
Economy and Competitiveness) to JS
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