6,092 research outputs found
Density reorganization in hot nuclei
The density profile of a hot nuclear system produced in intermediate energy
heavy ion collisions is studied in a microcanonical formulation with a momentum
and density dependent finite range interaction. The caloric curve and the
density evolution with excitation are calculated for a number of systems for
the equilibrium mononuclear configuration; they compare favorably with the
recent experimental data. The studied density fluctuations are seen to build up
rapidly beyond an excitation energy of 8 MeV/u indicating the instability of
the system towards nuclear disassembly. Explicit introduction of deformation in
the expansion path of the heated nucleus, however, shows that the system might
fragment even earlier. We also explore the effects of the nuclear equation of
state and of the mass and isospin asymmetry on the nuclear equilibrium
configuration and the relevant experimental observables.Comment: 20 pages, 12 figures, revtex
Accountability in patenting of federally funded research
Bayh-Dole allows academic grantees to patent federally-funded research for purposes of promoting the commercialization of this research. To ensure commercialization goals are achieved, the Act requires grantees to report to funding agencies not only the existence of federally-funded patents but also utilization efforts they and their licensees/assignees are making.
Although reporting is a cornerstone of accountability under Bayh-Dole, information about grantee compliance with reporting requirements is incomplete and dated. In fact, the last significant study of the question dates back to the late 1990s and analyzes only 633 patents. Since that time, concerns have emerged that federally-funded university patents are being asserted improperly against independent commercializers or even assigned to so-called “patent trolls.”
This article provides fresh evidence indicating substantial under-reporting of the existence of federal funding in over 30,000 academic biomedical patents issued between 1980 to 2007. The article finds substantial under-reporting of federal funding even in the case of patents on FDA-approved drugs, which should presumably receive significant attention from universities.
Grantees’ failure to report federal funding suggests similar, or even more significant, noncompliance with requirements to report utilization information. However, compliance with reporting requirements on utilization cannot be assessed because of secrecy associated with relevant government databases. Accordingly, the article makes a fresh argument that the Commerce Department, which has the requisite regulatory authority, work with funding agencies, to improve transparency. Greater transparency would not only motivate grantees to improve reporting but would also allow assessment of whether grantee patent management is actually achieving Bayh-Dole\u27s utilization goals
Stability of vortex solitons in a photorefractive optical lattice
Stability of off-site vortex solitons in a photorefractive optical lattice is
analyzed. It is shown that such solitons are linearly unstable in both the high
and low intensity limits. In the high-intensity limit, the vortex looks like a
familiar ring vortex, and it suffers oscillatory instabilities. In the
low-intensity limit, the vortex suffers both oscillatory and Vakhitov-Kolokolov
instabilities. However, in the moderate-intensity regime, the vortex becomes
stable if the lattice intensity or the applied voltage is above a certain
threshold value. Stability regions of vortices are also determined at typical
experimental parameters.Comment: 3 pages, 5 figure
Latent variable modeling to develop a robust proxy for sensitive behaviors: application to latrine use behavior and its association with sanitation access in a middle-income country
Abstract
Background
Globally, diarrhea is a leading cause of child morbidity and mortality. Although latrines are integral for reducing enteric pathogen transmission, several studies have shown no evidence that latrine ownership improved child health. There are a number of explanations for these results. One explanation is that latrine access does not equate to latrine use. Latrine use, however, is difficult to accurately ascertain, as defecation behavior is often stigmatized. To address this measurement issue, we measure latrine use as a latent variable, indicated by a suite of psychosocial variables.
Methods
We administered a survey of 16 defecation-related psychosocial questions to 251 individuals living in rural Ecuador. We applied latent class analysis (LCA) to these data to model the probability of latrine use as a latent variable. To account for uncertainty in predicted latent class membership, we used a pseudo-class approach to impute five different probabilities of latrine use for each respondent. Via regression modeling, we tested the association between household sanitation and each imputed latrine use variable.
Results
The optimal model presented strong evidence of two latent classes (entropy = 0.86): consistent users (78%) and inconsistent users (22%), predicted by 5 of our 16 psychosocial variables. There was no evidence of an association between the probability of latrine use, predicted from the LCA, and household access to basic sanitation (OR = 1.1, 95% CI = 0.6–2.1). This suggests that home access to a sanitation facility may not ensure the use of the facility for every family member at all times.
Conclusion
Effective implementation and evaluation of sanitation programs requires accurate measurement of latrine use. Psychosocial variables, such as norms, perceptions, and attitudes may provide robust proxy-measures. Future longitudinal studies will help to strengthen the use of these surrogate measures, as many of these factors may be subject to secular trends. Additionally, subgroup analyses will elucidate how our proxy indicators of latrine defecation vary by individual-level characteristics.https://deepblue.lib.umich.edu/bitstream/2027.42/147344/1/12889_2018_Article_6373.pd
Network Cournot Competition
Cournot competition is a fundamental economic model that represents firms
competing in a single market of a homogeneous good. Each firm tries to maximize
its utility---a function of the production cost as well as market price of the
product---by deciding on the amount of production. In today's dynamic and
diverse economy, many firms often compete in more than one market
simultaneously, i.e., each market might be shared among a subset of these
firms. In this situation, a bipartite graph models the access restriction where
firms are on one side, markets are on the other side, and edges demonstrate
whether a firm has access to a market or not. We call this game \emph{Network
Cournot Competition} (NCC). In this paper, we propose algorithms for finding
pure Nash equilibria of NCC games in different situations. First, we carefully
design a potential function for NCC, when the price functions for markets are
linear functions of the production in that market. However, for nonlinear price
functions, this approach is not feasible. We model the problem as a nonlinear
complementarity problem in this case, and design a polynomial-time algorithm
that finds an equilibrium of the game for strongly convex cost functions and
strongly monotone revenue functions. We also explore the class of price
functions that ensures strong monotonicity of the revenue function, and show it
consists of a broad class of functions. Moreover, we discuss the uniqueness of
equilibria in both of these cases which means our algorithms find the unique
equilibria of the games. Last but not least, when the cost of production in one
market is independent from the cost of production in other markets for all
firms, the problem can be separated into several independent classical
\emph{Cournot Oligopoly} problems. We give the first combinatorial algorithm
for this widely studied problem
The role of cognitive emotion regulation on the vicarious emotional response
Perceiving another in need may provoke two possible emotional responses: empathic concern and personal distress. This research aims to test whether different emotion regulation strategies (i.e., reappraisal and rumination) may lead to different vicarious emotional responses (i.e., empathic concern and personal distress). In this sense, we hypothesized that reappraisal may lead to a greater feeling of empathic concern, whereas rumination may lead to a higher feeling of personal distress. To test the hypotheses we used experimental instructions (Study 1) and a priming procedure (Study 2) to manipulate the emotion regulation strategies. The results supported our hypotheses. Furthermore in the rumination condition the emotional experience was described as being more negative and more highly arousing than in the reappraisal condition. We discuss the effect of these two forms of cognitive emotion regulation on empathic concern and personal distress
Nucleonic resonance excitations with linearly polarized photon in
In this work, an improved quark model approach to the meson
photo-production with an effective Lagrangian is presented. The {\it t}-channel
{\it natural}-parity exchange is taken into account through the Pomeron
exchange, while the {\it unnatural}-parity exchange is described by the
exchange. With a very limited number of parameters, the available experimental
data in the low energy regime can be consistently accounted for. We find that
the beam polarization observables show sensitivities to some {\it s}-channel
individual resonances in the quark model symmetry limit.
Especially, the two resonances and , which belong
to the representation , have dominant contributions
over other excited states. Concerning the essential motivation of searching for
"missing resonances" in meson photo-production, this approach provides a
feasible framework, on which systematic investigations can be done.Comment: 16 pages, Revtex, 9 eps figures, to appear in PR
Vector Meson Photoproduction with an Effective Lagrangian in the Quark Model
A quark model approach to the photoproduction of vector mesons off nucleons
is proposed. Its starting point is an effective Lagrangian of the interaction
between the vector meson and the quarks inside the baryon, which generates the
non-diffractive s- and u- channel resonance contributions. Additional t-channel
and exchanges are included for the and
production respectively to account for the large diffractive behavior in the
small region as suggested by Friman and Soyeur. The numerical results are
presented for the and productions in four isospin channels with
the same set of parameters, and they are in good agreement with the available
data not only in and productions but also in the charged
productions where the additional t-channel exchange does not
contribute so that it provides an important test to this approach. The
investigation is also extended to the photoproduction, and the initial
results show that the non-diffractive behavior of the productions in the
large region can be described by the s- and u- channel contributions with
significantly smaller coupling constants, which is consistent with the findings
in the similar studies in the QHD framework. The numerical investigation has
also shown that polarization observables are essential for identifying
so-called "missing resonances".Comment: 36 pages, 10 PS figures, extended version of nucl-th/9711061 and
nucl-th/9803021, submitted to PR
Inclusive Particle Spectra at RHIC
A simulation is performed of the recently reported data from PHOBOS at
energies of 56 and 130 A GeV using the relativistic heavy ion cascade LUCIFER
which had previously given a good description of the NA49 inclusive spectra at
E=17.2 A GeV. The results compare well with these early measurements at RHIC.Comment: 4 pages, 2 figure
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