181 research outputs found
A Topological Glass
We propose and study a model with glassy behavior. The state space of the
model is given by all triangulations of a sphere with nodes, half of which
are red and half are blue. Red nodes want to have 5 neighbors while blue ones
want 7. Energies of nodes with different numbers of neighbors are supposed to
be positive. The dynamics is that of flipping the diagonal of two adjacent
triangles, with a temperature dependent probability. We show that this system
has an approach to a steady state which is exponentially slow, and show that
the stationary state is unordered. We also study the local energy landscape and
show that it has the hierarchical structure known from spin glasses. Finally,
we show that the evolution can be described as that of a rarefied gas with
spontaneous generation of particles and annihilating collisions
First-order transition of tethered membranes in 3d space
We study a model of phantom tethered membranes, embedded in three-dimensional
space, by extensive Monte Carlo simulations. The membranes have hexagonal
lattice structure where each monomer is interacting with six nearest-neighbors
(NN). Tethering interaction between NN, as well as curvature penalty between NN
triangles are taken into account. This model is new in the sense that NN
interactions are taken into account by a truncated Lennard-Jones potential
including both repulsive and attractive parts. The main result of our study is
that the system undergoes a first-order crumpling transition from low
temperature flat phase to high temperature crumpled phase, in contrast with
early numerical results on models of tethered membranes.Comment: 5 pages, 6 figure
Phase transition of meshwork models for spherical membranes
We have studied two types of meshwork models by using the canonical Monte
Carlo simulation technique. The first meshwork model has elastic junctions,
which are composed of vertices, bonds, and triangles, while the second model
has rigid junctions, which are hexagonal (or pentagonal) rigid plates.
Two-dimensional elasticity is assumed only at the elastic junctions in the
first model, and no two-dimensional bending elasticity is assumed in the second
model. Both of the meshworks are of spherical topology. We find that both
models undergo a first-order collapsing transition between the smooth spherical
phase and the collapsed phase. The Hausdorff dimension of the smooth phase is
H\simeq 2 in both models as expected. It is also found that H\simeq 2 in the
collapsed phase of the second model, and that H is relatively larger than 2 in
the collapsed phase of the first model, but it remains in the physical bound,
i.e., H<3. Moreover, the first model undergoes a discontinuous surface
fluctuation transition at the same transition point as that of the collapsing
transition, while the second model undergoes a continuous transition of surface
fluctuation. This indicates that the phase structure of the meshwork model is
weakly dependent on the elasticity at the junctions.Comment: 21 pages, 12 figure
Folate catabolites in spot urine as non-invasive biomarkers of folate status during habitual intake and folic acid supplementation.
Folate status, as reflected by red blood cell (RCF) and plasma folates (PF), is related to health and disease risk. Folate degradation products para-aminobenzoylglutamate (pABG) and para-acetamidobenzoylglutamate (apABG) in 24 hour urine have recently been shown to correlate with blood folate.
Since blood sampling and collection of 24 hour urine are cumbersome, we investigated whether the determination of urinary folate catabolites in fasted spot urine is a suitable non-invasive biomarker for folate status in subjects before and during folic acid supplementation.
Immediate effects of oral folic acid bolus intake on urinary folate catabolites were assessed in a short-term pre-study. In the main study we included 53 healthy men. Of these, 29 were selected for a 12 week folic acid supplementation (400 ”g). Blood, 24 hour and spot urine were collected at baseline and after 6 and 12 weeks and PF, RCF, urinary apABG and pABG were determined.
Intake of a 400 ”g folic acid bolus resulted in immediate increase of urinary catabolites. In the main study pABG and apABG concentrations in spot urine correlated well with their excretion in 24 hour urine. In healthy men consuming habitual diet, pABG showed closer correlation with PF (rsâ=â0.676) and RCF (rsâ=â0.649) than apABG (rsâ=â0.264, ns and 0.543). Supplementation led to significantly increased folate in plasma and red cells as well as elevated urinary folate catabolites, while only pABG correlated significantly with PF (rsâ=â0.574) after 12 weeks.
Quantification of folate catabolites in fasted spot urine seems suitable as a non-invasive alternative to blood or 24 hour urine analysis for evaluation of folate status in populations consuming habitual diet. In non-steady-state conditions (folic acid supplementation) correlations between folate marker (RCF, PF, urinary catabolites) decrease due to differing kinetics
Collective and broken pair states of 65,67Ga
Excited states of 65Ga and 67Ga nuclei were populated through the 12C(58Ni,αp) and 12C(58Ni,3p) reactions, respectively, and investigated by in-beam Îł-ray spectroscopic methods. The NORDBALL array equipped with a charged particle ball and 11 neutron detectors was used to detect the evaporated particles and Îł rays. The level schemes of 65,67Ga were constructed on the basis of γγ-coincidence relations up to 8.6 and 10 MeV excitation energy, and IÏ=27/2 and 33/2+ spin and parity, respectively. The structure of 65,67Ga nuclei was described in the interacting boson-fermion plus broken pair model, including quasiproton, quasiproton-two-quasineutron, and three-quasiproton fermion configurations in the boson-fermion basis states. Most of the states were assigned to quasiparticle + phonon and three quasiparticle configurations on the basis of their electromagnetic decay properties
Evidence for a spin-aligned neutron-proton paired phase from the level structure of Pd
The general phenomenon of shell structure in atomic nuclei has been
understood since the pioneering work of Goeppert-Mayer, Haxel, Jensen and
Suess.They realized that the experimental evidence for nuclear magic numbers
could be explained by introducing a strong spin-orbit interaction in the
nuclear shell model potential. However, our detailed knowledge of nuclear
forces and the mechanisms governing the structure of nuclei, in particular far
from stability, is still incomplete. In nuclei with equal neutron and proton
numbers (), the unique nature of the atomic nucleus as an object
composed of two distinct types of fermions can be expressed as enhanced
correlations arising between neutrons and protons occupying orbitals with the
same quantum numbers. Such correlations have been predicted to favor a new type
of nuclear superfluidity; isoscalar neutron-proton pairing, in addition to
normal isovector pairing (see Fig. 1). Despite many experimental efforts these
predictions have not been confirmed. Here, we report on the first observation
of excited states in nucleus Pd. Gamma rays emitted
following the Ni(Ar,2)Pd fusion-evaporation reaction
were identified using a combination of state-of-the-art high-resolution
{\gamma}-ray, charged-particle and neutron detector systems. Our results reveal
evidence for a spin-aligned, isoscalar neutron-proton coupling scheme,
different from the previous prediction. We suggest that this coupling scheme
replaces normal superfluidity (characterized by seniority coupling) in the
ground and low-lying excited states of the heaviest N = Z nuclei. The strong
isoscalar neutron- proton correlations in these nuclei are predicted to
have a considerable impact on their level structures, and to influence the
dynamics of the stellar rapid proton capture nucleosynthesis process.Comment: 13 pages, 3 figure
Effects of cognitive-behavioral programs for criminal offenders
Cognitive-behavioral therapy (CBT) is among the more promising rehabilitative treatments for
criminal offenders. Reviews of the comparative effectiveness of different treatment approaches
have generally ranked it in the top tier with regard to effects on recidivism (e.g., Andrews et al.,
1990; Lipsey & Wilson, 1998). It has a well-developed theoretical basis that explicitly targets
âcriminal thinkingâ as a contributing factor to deviant behavior (Beck, 1999; Walters, 1990;
Yochelson & Samenow, 1976). And, it can be adapted to a range of juvenile and adult
offenders, delivered in institutional or community settings by mental health specialists or
paraprofessionals, and administered as part of a multifaceted program or as a stand-alone
intervention. Meta-analysis has consistently indicated that CBT, on average, has significant
positive effects on recidivism. However, there is also significant variation across studies in the
size of those treatment effects. Identification of the moderator variables that describe the study
characteristics associated with larger and smaller effects can further develop our understanding
of the effectiveness of CBT with offenders. Of particular importance is the role such moderator
analysis can play in ascertaining which variants of CBT are most effective. The objective of this
systematic review is to examine the relationships of selected moderator variables to the effects
of CBT on the recidivism of general offender populations
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