14,008 research outputs found
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
Entropic Effects in the Very Low Temperature Regime of Diluted Ising Spin Glasses with Discrete Couplings
We study link-diluted Ising spin glass models on the hierarchical
lattice and on a three-dimensional lattice close to the percolation threshold.
We show that previously computed zero temperature fixed points are unstable
with respect to temperature perturbations and do not belong to any critical
line in the dilution-temperature plane. We discuss implications of the presence
of such spurious unstable fixed points on the use of optimization algorithms,
and we show how entropic effects should be taken into account to obtain the
right physical behavior and critical points.Comment: 4 pages, 4 figures. A major typo error in formula (8) has been
correcte
Single Superconducting Split-Ring Resonator Electrodynamics
We investigate the microwave electrodynamic properties of a single
superconducting thin film split-ring resonator (SRR). The experiments were
performed in an all-Nb waveguide, with Nb wires and Nb SRRs. Transmission data
showed a high-Q stopband for a single Nb SRR ( at 4.2 K)
below , and no such feature for a Cu SRR, or closed Nb loops, of similar
dimensions. Adding SRRs increased the bandwidth, but decreased the insertion
loss of the features. Placing the Nb SRR into an array of wires produced a
single, elementary negative-index passband ( at 4.2 K).
Changes in the features due to the superconducting kinetic inductance were
observed. Models for the SRR permeability, and the wire dielectric response,
were used to fit the data.Comment: 4 pages, 3 figures, RevTex, submitted to Applied Physics Letters.
Updated version includes mention of bianisotropy, better looking figures, and
different temperature dat
BeppoSAX LECS background subtraction techniques
We present 3 methods for the subtraction of non-cosmic and unresolved cosmic
backgrounds observed by the Low-Energy Concentrator Spectrometer (LECS)
on-board BeppoSAX. Removal of these backgrounds allows a more accurate modeling
of the spectral data from point and small-scale extended sources. At high
(>|25| degree) galactic latitudes, subtraction using a standard background
spectrum works well. At low galactic latitudes, or in complex regions of the
X-ray sky, two alternative methods are presented. The first uses counts
obtained from two semi-annuli near the outside of the LECS field of view to
estimate the background at the source location. The second method uses ROSAT
Position Sensitive Proportional Counter (PSPC) all-sky survey data to estimate
the LECS background spectrum for a given pointing position. A comparison of the
results from these methods provides an estimate of the systematic
uncertainties. For high galactic latitude fields, all 3 methods give 3 sigma
confidence uncertainties of <0.9 10^-3 count/s (0.1-10 keV), or <1.5 10^-3
count/s (0.1-2 keV). These correspond to 0.1-2.0 keV fluxes of 0.7-1.8 and
0.5-1.1 10^-13 erg/cm2/s for a power-law spectrum with a photon index of 2 and
photoelectric absorption of 3 10^20 and 3 10^21 atom/cm2, respectively. At low
galactic latitudes, or in complex regions of the X-ray sky, the uncertainties
are a factor ~2.5 higher.Comment: 13 pages. Accepted for publication in A&A
Finite size corrections to disordered systems on Erd\"{o}s-R\'enyi random graphs
We study the finite size corrections to the free energy density in disorder
spin systems on sparse random graphs, using both replica theory and cavity
method. We derive an analytical expressions for the corrections in the
replica symmetric phase as a linear combination of the free energies of open
and closed chains. We perform a numerical check of the formulae on the Random
Field Ising Model at zero temperature, by computing finite size corrections to
the ground state energy density.Comment: Submitted to PR
A year in the life of GW170817: the rise and fall of a structured jet from a binary neutron star merger
We present the results of our year-long afterglow monitoring of GW170817, the
first binary neutron star (NS) merger detected by advanced LIGO and advanced
Virgo. New observations with the Australian Telescope Compact Array (ATCA) and
the Chandra X-ray Telescope were used to constrain its late-time behavior. The
broadband emission, from radio to X-rays, is well-described by a simple
power-law spectrum with index ~0.585 at all epochs. After an initial shallow
rise ~t^0.9, the afterglow displayed a smooth turn-over, reaching a peak X-ray
luminosity of ~5e39 erg/s at 160 d, and has now entered a phase of rapid
decline ~t^(-2). The latest temporal trend challenges most models of choked
jet/cocoon systems, and is instead consistent with the emergence of a
relativistic structured jet seen at an angle of ~22 deg from its axis. Within
such model, the properties of the explosion (such as its blastwave energy
E_K~2E50 erg, jet width theta_c~4 deg, and ambient density n~3E-3 cm^(-3)) fit
well within the range of properties of cosmological short GRBs.Comment: 11 pages, 8 figures, 2 tables, MNRAS, in press. Final version, minor
changes only relative to original submission dated 21 August 201
Temperature Chaos, Rejuvenation and Memory in Migdal-Kadanoff Spin Glasses
We use simulations within the Migdal-Kadanoff real space renormalization
approach to probe the scales relevant for rejuvenation and memory in spin
glasses. One of the central questions concerns the role of temperature chaos.
First we investigate scaling laws of equilibrium temperature chaos, finding
super-exponential decay of correlations but no chaos for the total free energy.
Then we perform out of equilibrium simulations that follow experimental
protocols. We find that: (1) rejuvenation arises at a length scale smaller than
the ``overlap length'' l(T,T'); (2) memory survives even if equilibration goes
out to length scales much larger than l(T,T').Comment: 4 pages, 4 figures, added references, slightly changed content,
modified Fig.
Characterizing and Improving Generalized Belief Propagation Algorithms on the 2D Edwards-Anderson Model
We study the performance of different message passing algorithms in the two
dimensional Edwards Anderson model. We show that the standard Belief
Propagation (BP) algorithm converges only at high temperature to a paramagnetic
solution. Then, we test a Generalized Belief Propagation (GBP) algorithm,
derived from a Cluster Variational Method (CVM) at the plaquette level. We
compare its performance with BP and with other algorithms derived under the
same approximation: Double Loop (DL) and a two-ways message passing algorithm
(HAK). The plaquette-CVM approximation improves BP in at least three ways: the
quality of the paramagnetic solution at high temperatures, a better estimate
(lower) for the critical temperature, and the fact that the GBP message passing
algorithm converges also to non paramagnetic solutions. The lack of convergence
of the standard GBP message passing algorithm at low temperatures seems to be
related to the implementation details and not to the appearance of long range
order. In fact, we prove that a gauge invariance of the constrained CVM free
energy can be exploited to derive a new message passing algorithm which
converges at even lower temperatures. In all its region of convergence this new
algorithm is faster than HAK and DL by some orders of magnitude.Comment: 19 pages, 13 figure
Millimetre spectral indices of transition disks and their relation to the cavity radius
Transition disks are protoplanetary disks with inner depleted dust cavities
and excellent candidates to investigate the dust evolution under the existence
of a pressure bump. A pressure bump at the outer edge of the cavity allows dust
grains from the outer regions to stop their rapid inward migration towards the
star and efficiently grow to millimetre sizes. Dynamical interactions with
planet(s) have been one of the most exciting theories to explain the clearing
of the inner disk. We look for evidence of the presence of millimetre dust
particles in transition disks by measuring their spectral index with new and
available photometric data. We investigate the influence of the size of the
dust depleted cavity on the disk integrated millimetre spectral index. We
present the 3mm photometric observations carried out with PdBI of four
transition disks: LkHa330, UXTauA, LRLL31, and LRLL67. We use available values
of their fluxes at 345GHz to calculate their spectral index, as well as the
spectral index for a sample of twenty transition disks. We compare the
observations with two kind of models. In the first set of models, we consider
coagulation and fragmentation of dust in a disk in which a cavity is formed by
a massive planet located at different positions. The second set of models
assumes disks with truncated inner parts at different radius and with power-law
dust size distributions, where the maximum size of grains is calculated
considering turbulence as the source of destructive collisions. We show that
the integrated spectral index is higher for transition disks than for regular
protoplanetary disks. For transition disks, the probability that the measured
spectral index is positively correlated with the cavity radius is 95%. High
angular resolution imaging of transition disks is needed to distinguish between
the dust trapping scenario and the truncated disk case.Comment: Accepted for publication in A&A, including language editio
Instability of one-step replica-symmetry-broken phase in satisfiability problems
We reconsider the one-step replica-symmetry-breaking (1RSB) solutions of two
random combinatorial problems: k-XORSAT and k-SAT. We present a general method
for establishing the stability of these solutions with respect to further steps
of replica-symmetry breaking. Our approach extends the ideas of [A.Montanari
and F. Ricci-Tersenghi, Eur.Phys.J. B 33, 339 (2003)] to more general
combinatorial problems.
It turns out that 1RSB is always unstable at sufficiently small clauses
density alpha or high energy. In particular, the recent 1RSB solution to 3-SAT
is unstable at zero energy for alpha< alpha_m, with alpha_m\approx 4.153. On
the other hand, the SAT-UNSAT phase transition seems to be correctly described
within 1RSB.Comment: 26 pages, 7 eps figure
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