5,503 research outputs found
Constraints on Gravitino Decay and the Scale of Inflation using CMB spectral distortions
If local supersymmetry is the correct extension of the standard model of
particle physics, then following Inflation the early universe would have been
populated by gravitinos produced from scatterings in the hot plasma during
reheating. Their abundance is directly related to the magnitude of the
reheating temperature. The gravitino lifetime is fixed as a function of its
mass, and for gravitinos with lifetimes longer than the age of the universe at
redshift (or roughly ), decay
products can produce spectral distortion of the cosmic microwave background.
Currently available COBE/FIRAS limits on spectral distortion can, in certain
cases, already be competitive with respect to cosmological constraints from
primordial nucleosynthesis for some gravitino decay scenarios. We show how the
sensitivity limits on and distortions that can be reached with
current technology would improve constraints and possibly rule out a
significant portion of the parameter space for gravitino masses and Inflation
reheating temperatures.Comment: submitted to Phys. Rev D., 8 pages, 4 figs (1 new figure added,
references updated
Elective affinities
We propose a marriage model where assortative matching results in equilibrium for reasons other than those driving similar results in the search and matching literature. A marriage is a joint venture where husband and wife contribute to the couple’s welfare by allocating their time to portfolios of risky activities. Men and women are characterised by different preferences over risk and the optimal match is between partners with the same level of risk aversion. In our model no two men (women) rank the same woman (men) as most desirable. Given that there is no unanimous ranking of candidates, everyone marries in equilibrium their most preferred partne
Theoretical and numerical study of the phase diagram of patchy colloids: ordered and disordered patch arrangements
We report theoretical and numerical evaluations of the phase diagram for a
model of patchy particles. Specifically we study hard-spheres whose surface is
decorated by a small number f of identical sites ("sticky spots'') interacting
via a short-range square-well attraction. We theoretically evaluate, solving
the Wertheim theory, the location of the critical point and the gas-liquid
coexistence line for several values of f and compare them to results of Gibbs
and Grand Canonical Monte Carlo simulations. We study both ordered and
disordered arrangements of the sites on the hard-sphere surface and confirm
that patchiness has a strong effect on the phase diagram: the gas-liquid
coexistence region in the temperature-density plane is significantly reduced as
f decreases. We also theoretically evaluate the locus of specific heat maxima
and the percolation line.Comment: preprint, 32 pages, 6 figures, 3 tables, J. Chem. Phys. in pres
Legal medical consideration of alzheimer’s disease patients’ dysgraphia and cognitive dysfunction: a 6 month follow up
Background: The purpose of this study was to investigate the ability of Alzheimer’s disease
(AD) patients to express intentions and desires, and their decision-making capacity. This study
examines the findings from a 6-month follow-up of our previous results in which 30 patients
participated.
Materials and methods: The patient’s cognition was examined by conducting the tests of 14
questions and letter-writing ability over a period of 19 days, and it was repeated after 6 months.
The difference between these two cognitive measures (PQ1 before–PQ2 before), tested previously
and later the writing test, was designated DΔ before. The test was repeated after 6 months,
and PQ1 after–PQ2 after was designated DΔ after.
Results: Several markedly strong relationships between dysgraphia and other measures of
cognitive performance in AD patients were observed. The most aged patients (over 86 years),
despite less frequency, maintain the cognitive capacity manifested in the graphic expressions.
A document, written by an AD patient presents an honest expression of the patient’s intention
if that document is legible, clear, and comprehensive.
Conclusion: The identification of impairment/deficits in writing and cognition during different
phases of AD may facilitate the understanding of disease progression and identify the occasions
during which the patient may be considered sufficiently lucid to make decisions.
Keywords: cognition, intentions, unfit to plead, consen
Reheating predictions in single field inflation
Reheating is a transition era after the end of inflation, during which the
inflaton is converted into the particles that populate the Universe at later
times. No direct cosmological observables are normally traceable to this period
of reheating. Indirect bounds can however be derived. One possibility is to
consider cosmological evolution for observable CMB scales from the time of
Hubble crossing to the present time. Depending upon the model, the duration and
final temperature after reheating, as well as its equation of state, may be
directly linked to inflationary observables. For single-field inflationary
models, if we approximate reheating by a constant equation of state, one can
derive relations between the reheating duration (or final temperature), its
equation of state parameter, and the scalar power spectrum amplitude and
spectral index. While this is a simple approximation, by restricting the
equation of state to lie within a broad physically allowed range, one can in
turn bracket an allowed range of and for these models. The added
constraints can help break degeneracies between inflation models that otherwise
overlap in their predictions for and .Comment: 32 pages, 15 figures. Revised in response to comments on the original
version, and in preparation for submission for publication. More references
and a new figure were adde
Tuning effective interactions close to the critical point in colloidal suspensions
We report a numerical investigation of two colloids immersed in a critical
solvent, with the aim of quantifying the effective colloid-colloid interaction
potential. By turning on an attraction between the colloid and the solvent
particles we follow the evolution from the case in which the solvent density
close to the colloids changes from values smaller than the bulk to values
larger than the bulk. We thus effectively implement the so-called and
boundary conditions defined in field theoretical approaches focused on
the description of critical Casimir forces. We find that the effective
potential at large distances decays exponentially, with a characteristic decay
length compatible with the bulk critical correlation length, in full agreement
with theoretical predictions. We also investigate the case of boundary
condition, where the effective potential becomes repulsive. Our study provides
a guidance for a design of the interaction potential which can be exploited to
control the stability of colloidal systems
Central Sensitization in the Bladder Pain Syndrome
Introduction: Nociceptive hyper-excitability and Central Sensitization (CS), have been identified as responsible for maintaining pain in several chronic neuropathic pain conditions, among which Bladder pain syndrome (BPS). Aim of the present study was to evaluate in patients with BPS the correlation between CS and the following items pain duration, the number of other CS related diseases, the number of tried treatments for pain and of diagnostic investigations before the proper diagnosis and to identify the cut-off value of the pain delays for predicting the worsening of sensitization. Method: Fifty-eight consecutively BPS outpatients were recruited from 2014 to 2016. They were submitted to Central Sensitization Inventory (CSI), Overactive Bladder Questionnaire (OAB-8v) and visual analogic scale (VAS) for pain. We used a descriptive analysis (mean, standard deviation, range) and Spearman and Kendall test coefficient as correlation index. One-way ANOVA test was used for the comparison between groups. P-value less than 0.05 were required for statistical significance. We used receiver operating characteristic (ROC) curve analysis to retrospectively analyze the association between the years of the disease and pathological values o of CSI. Results: The patients were observed after 13.1 + 11.0 years by the onset of The CSI score was 69.7+15.8. Resulting significantly lower in patients with BPS onset in the last year the correlation between CSI and the disease duration was significant. The number of previous investigations was 3.7 + 2.8while the number of previous treatments for chronic pain was 5.9 + 3.1, resulting significantly related to CSI score. The OAB-8v was 21 + 7.5 (range 2-34). The worsening of the symptoms related to the overactive bladder at OAB-8v was related to a greater CS. After 1,5 years of the onset of the pain the CS show a progressive worsening. The mean number of other diseases (fibromyalgia, irritable bowel syndrome, anxiety or depression, migraine, neck injury, Panic Disorder Attack, chronic fatigue syndrome, temporomandibular joint syndrome, restless leg syndrome, multiple chemical sensitivities) associated to CS was 2.8+1.9. The correlation between the number of diseases associated to CS and the years of disease resulted significant. Conclusion: Patients with long lasting pelvic pain show high levels of CS, and other central sensitivity syndromes (CSS) together to worsening of overactive bladder symptoms, and increasing number of used drugs. The delay of diagnosis is related to a greater sensitization process
Viscoelasticity and Stokes-Einstein relation in repulsive and attractive colloidal glasses
We report a numerical investigation of the visco-elastic behavior in models
for steric repulsive and short-range attractive colloidal suspensions, along
different paths in the attraction-strength vs packing fraction plane. More
specifically, we study the behavior of the viscosity (and its frequency
dependence) on approaching the repulsive glass, the attractive glass and in the
re-entrant region where viscosity shows a non monotonic behavior on increasing
attraction strength. On approaching the glass lines, the increase of the
viscosity is consistent with a power-law divergence with the same exponent and
critical packing fraction previously obtained for the divergence of the density
fluctuations. Based on mode-coupling calculations, we associate the increase of
the viscosity with specific contributions from different length scales. We also
show that the results are independent on the microscopic dynamics by comparing
newtonian and brownian simulations for the same model. Finally we evaluate the
Stokes-Einstein relation approaching both glass transitions, finding a clear
breakdown which is particularly strong for the case of the attractive glass.Comment: 12 pages; sent to J. Chem. Phy
Probing a critical length scale at the glass transition
We give evidence of a clear structural signature of the glass transition, in
terms of a static correlation length with the same dependence on the system
size which is typical of critical phenomena. Our approach is to introduce an
external, static perturbation to extract the structural information from the
system's response. In particular, we consider the transformation behavior of
the local minima of the underlying potential energy landscape (inherent
structures), under a static deformation. The finite-size scaling analysis of
our numerical results indicate that the correlation length diverges at a
temperature , below the temperatures here the system can be equilibrated.
Our numerical results are consistent with random first order theory, which
predicts such a divergence with a critical exponent at the Kauzmann
temperature, where the extrapolated configurational entropy vanishes.Comment: 5 pages, 5 figures, to appear in Phys. Rev. Lett. 2010
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