2,252 research outputs found
Application of ERTS-1 Imagery to Flood Inundation Mapping
Application of ERTS-1 imagery to flood inundation mapping in East and West Nishnabotna basins of southwestern Iow
Are we providing patient-centered care? Preferences about paracentesis and thoracentesis procedures
Procedures performed at the bedside are as safe and less expensive than Interventional Radiology (IR) procedures. Patient preferences regarding location are rarely taken into account. Therefore, in this study we compared patient satisfaction with bedside and IR paracentesis and thoracentesis procedures, and identified reasons for patient location preferences. We performed a cross-sectional survey of medical inpatients undergoing paracentesis or thoracentesis procedures at a tertiary care academic medical center. The survey had eight domains: overall experience, pain control, expertise, courtesy, bedside manner of the physician, time required, explanation of risks/benefits, comfort and privacy. Patients were also asked about their preference for procedure location.
Two hundred and twenty surveys (162 paracentesis and 58 thoracentesis) were completed on 152 patients. Patient satisfaction was similar for bedside and IR procedures across all domains. A location preference was expressed in 151 surveys (68.6%). Thirty-five of 108 responses (32.4%) from patients with a paracentesis expressed a preference for bedside procedures while 73/108 (67.6%) responses expressed a preference for IR. Twenty-eight of 43 responses (65.1%) from patients with a thoracentesis expressed a preference for bedside procedures while 15/43 (34.9%) responses expressed a preference for IR. Comfort was listed as the most common reason for preferring the bedside while specialized equipment and safety were the most common reasons for preferring IR. Patients are equally and highly satisfied with bedside and IR paracentesis and thoracentesis procedures. Because both approaches are safe and effective, clinicians should pursue informed discussions with patients when a choice is available
Non-Negative Local Sparse Coding for Subspace Clustering
Subspace sparse coding (SSC) algorithms have proven to be beneficial to
clustering problems. They provide an alternative data representation in which
the underlying structure of the clusters can be better captured. However, most
of the research in this area is mainly focused on enhancing the sparse coding
part of the problem. In contrast, we introduce a novel objective term in our
proposed SSC framework which focuses on the separability of data points in the
coding space. We also provide mathematical insights into how this
local-separability term improves the clustering result of the SSC framework.
Our proposed non-linear local SSC algorithm (NLSSC) also benefits from the
efficient choice of its sparsity terms and constraints. The NLSSC algorithm is
also formulated in the kernel-based framework (NLKSSC) which can represent the
nonlinear structure of data. In addition, we address the possibility of having
redundancies in sparse coding results and its negative effect on graph-based
clustering problems. We introduce the link-restore post-processing step to
improve the representation graph of non-negative SSC algorithms such as ours.
Empirical evaluations on well-known clustering benchmarks show that our
proposed NLSSC framework results in better clusterings compared to the
state-of-the-art baselines and demonstrate the effectiveness of the
link-restore post-processing in improving the clustering accuracy via
correcting the broken links of the representation graph.Comment: 15 pages, IDA 2018 conferenc
Agricultural productivity in past societies: toward an empirically informed model for testing cultural evolutionary hypotheses
Agricultural productivity, and its variation in space and time, plays a fundamental role in many theories of human social evolution. However, we often lack systematic information about the productivity of past agricultural systems on a scale large enough to test these theories properly. The effect of climate on crop yields has received a great deal of attention resulting in a range of empirical and process-based models, yet the focus has primarily been on current or future conditions. In this paper, we argue for a “bottom-up” approach that estimates potential productivity based on information about the agricultural practices and technologies used in past societies. Of key theoretical interest is using this information to estimate the carrying high quality historical and archaeological information about past societies in order to infer the temporal and geographic patterns of change in agricultural productivity and potential. We discuss information we need to collect about past agricultural techniques and practices, and introduce a new databank initiative that we have developed for collating the best available historical and archaeological evidence. A key benefit of our approach lies in making explicit the steps in the estimation of past productivities and carrying capacities, and in being able to assess the effects of different modelling assumptions. This is undoubtedly an ambitious task, yet promises to provide important insights into fundamental aspects of past societies, enabling us to test more rigorously key hypotheses about human socio-cultural evolution
Explicit Model Realizing Parton-Hadron Duality
We present a model that realizes both resonance-Regge (Veneziano) and
parton-hadron (Bloom-Gilman) duality. We first review the features of the
Veneziano model and we discuss how parton-hadron duality appears in the
Bloom-Gilman model. Then we review limitations of the Veneziano model, namely
that the zero-width resonances in the Veneziano model violate unitarity and
Mandelstam analyticity. We discuss how such problems are alleviated in models
that construct dual amplitudes with Mandelstam analyticity (so-called DAMA
models). We then introduce a modified DAMA model, and we discuss its
properties. We present a pedagogical model for dual amplitudes and we construct
the nucleon structure function F2(x,Q2). We explicitly show that the resulting
structure function realizes both Veneziano and Bloom-Gilman duality.Comment: 11 pages, 8 figure
The stable climate of KELT-9b
Even among the most irradiated gas giants, so-called ultra-hot Jupiters, KELT-9b stands out as the hottest planet thus far discovered with a dayside temperature of over 4500 K. At these extreme irradiation levels, we expect an increase in heat redistribution efficiency and a low Bond albedo owed to an extended atmosphere with molecular hydrogen dissociation occurring on the planetary dayside. We present new photometric observations of the KELT-9 system throughout 4 full orbits and 9 separate occultations obtained by the 30 cm space telescope CHEOPS. The CHEOPS bandpass, located at optical wavelengths, captures the peak of the thermal emission spectrum of KELT-9b. In this work we simultaneously analyse CHEOPS phase curves along with public phase curves from TESS and Spitzer to infer joint constraints on the phase curve variation, gravity-darkened transits, and occultation depth in three bandpasses, as well as derive 2D temperature maps of the atmosphere at three different depths. We find a day-night heat redistribution efficiency of ~0.3 which confirms expectations of enhanced energy transfer to the planetary nightside due to dissociation and recombination of molecular hydrogen. We also calculate a Bond albedo consistent with zero. We find no evidence of variability of the brightness temperature of the planet, excluding variability greater than 1
On Forward J/\psi Production at Fermilab Tevatron
The D0 Collaboration has recently reported the measurement of J/\psi
production at low angle. We show here that the inclusion of color octet
contributions in any framework is able to reproduce this data.Comment: 1 page, Revtex, uses epsfig.sty, 2 postscript figure
Correlated errors in Hipparcos parallaxes towards the Pleiades and the Hyades
We show that the errors in the Hipparcos parallaxes towards the Pleiades and
the Hyades open clusters are spatially correlated over angular scales of 2 to 3
deg, with an amplitude of up to 2 mas. This correlation is stronger than
expected based on the analysis of the Hipparcos catalog. We predict the
parallaxes of individual cluster members, pi_pm, from their Hipparcos proper
motions, assuming that all cluster members have the same space velocity. We
compare pi_pm with their Hipparcos parallaxes, pi_Hip, and find that there are
significant spatial correlations in pi_Hip. We derive a distance modulus to the
Pleiades of 5.58 +- 0.18 mag using the radial-velocity gradient method. This
value, agrees very well with the distance modulus of 5.60 +- 0.04 mag
determined using the main-sequence fitting technique, compared with the value
of 5.33 +- 0.06 inferred from the average of the Hipparcos parallaxes of the
Pleiades members. We show that the difference between the main-sequence fitting
distance and the Hipparcos parallax distance can arise from spatially
correlated errors in the Hipparcos parallaxes of individual Pleiades members.
Although the Hipparcos parallax errors towards the Hyades are spatially
correlated in a manner similar to those of the Pleiades, the center of the
Hyades is located on a node of this spatial structure. Therefore, the parallax
errors cancel out when the average distance is estimated, leading to a mean
Hyades distance modulus that agrees with the pre-Hipparcos value. We speculate
that these spatial correlations are also responsible for the discrepant
distances that are inferred using the mean Hipparcos parallaxes to some open
clusters. Finally, we note that our conclusions are based on a purely geometric
method and do not rely on any models of stellar isochrones.Comment: 33 pages including 10 Figures, revised version accepted for
publication in Ap
Hadroproduction and Polarization of Charmonium
In the limit of heavy quark mass, the production cross section and
polarization of quarkonia can be calculated in perturbative QCD. We study the
-averaged production of charmonium states in collisions at
fixed target energies. The data on the relative production rates of \jp and
is found to disagree with leading twist QCD. The polarization of the
\jp indicates that the discrepancy is not due to poorly known parton
distributions nor to the size of higher order effects (-factors). Rather,
the disagreement suggests important higher twist corrections, as has been
surmised earlier from the nuclear target -dependence of the production cross
section.Comment: 19 page
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