409 research outputs found
Simulation of Lattice Polymers with Multi-Self-Overlap Ensemble
A novel family of dynamical Monte Carlo algorithms for lattice polymers is
proposed. Our central idea is to simulate an extended ensemble in which the
self-avoiding condition is systematically weakened. The degree of the
self-overlap is controlled in a similar manner as the multicanonical ensemble.
As a consequence, the ensemble --the multi-self-overlap ensemble-- contains
adequate portions of self-overlapping conformations as well as higher energy
ones. It is shown that the multi-self-overlap ensemble algorithm reproduce
correctly the canonical averages at finite temperatures of the HP model of
lattice proteins. Moreover, it outperforms massively a standard multicanonical
algorithm for a difficult example of a polymer with 8-stickers. Alternative
algorithm based on exchange Monte Carlo method is also discussed.Comment: 5 Pages, 4 Postscript figures, uses epsf.st
Chapter Sleep Spindles – As a Biomarker of Brain Function and Plasticity
Alternative & renewable energy sources & technolog
Sleep Spindles – As a Biomarker of Brain Function and Plasticity
Alternative & renewable energy sources & technolog
Superoxide dismutase analog (Tempol: 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine 1-oxyl) treatment restores erectile function in diabetes-induced impotence.
We hypothesized that the administration of the superoxide dismutase (SOD) mimetic Tempol (4-hydroxy-2, 2, 6, 6-tetramethylpiperidine 1-oxyl) may reverse diabetes-induced erectile dysfunction. To test this hypothesis, reactive oxygen species-related genes (SOD1, SOD2, GP x 1, CAT, NOS2, NOS3) were tested, erectile functional studies and immunohistochemical analysis were carried out in diabetic rats treated with or without Tempol. Thirty Sprague-Dawley (3-4 months old) rats were divided into three groups (n=10 each), 20 with diabetes (diabetic control and Tempol treatment) and 10 healthy controls. At 12 weeks after the induction of diabetes by streptozotocin and Tempol treatment, all groups underwent in vivo cavernous nerve stimulation. Rat crura were harvested and the expression of antioxidative defense enzymes were examined by semi-quantitative reverse transcriptase PCR (RT-PCR). To confirm the RT-PCR results, we carried out immunohistochemistry (IHC) for catalase (CAT) and iNOS (NOS2). Nitration of tyrosine groups in proteins was also examined by IHC. Mean intracavernous pressure in the diabetic group was significantly lower than in the healthy controls (P <0.001) and was reversed by Tempol treatment (P <0.0108). NOS2 protein expression was significantly increased in diabetic animals compared with healthy controls and Tempol restored NOS2 protein level. Nitrotyrosine was also higher in diabetic animals and although Tempol treatment decreased its formation, it remained higher than that found in healthy controls. This study suggests that Tempol treatment increased erectile function through modulating oxidative stress-related genes in diabetic rats. This is the first report about the relationship between diabetes-induced erectile dysfunction and oxidative stress, and antioxidative therapy using the superoxide dismutase mimetic, Tempol, to restore erectile function
Statistical Mechanics of Nonlinear On-line Learning for Ensemble Teachers
We analyze the generalization performance of a student in a model composed of
nonlinear perceptrons: a true teacher, ensemble teachers, and the student. We
calculate the generalization error of the student analytically or numerically
using statistical mechanics in the framework of on-line learning. We treat two
well-known learning rules: Hebbian learning and perceptron learning. As a
result, it is proven that the nonlinear model shows qualitatively different
behaviors from the linear model. Moreover, it is clarified that Hebbian
learning and perceptron learning show qualitatively different behaviors from
each other. In Hebbian learning, we can analytically obtain the solutions. In
this case, the generalization error monotonically decreases. The steady value
of the generalization error is independent of the learning rate. The larger the
number of teachers is and the more variety the ensemble teachers have, the
smaller the generalization error is. In perceptron learning, we have to
numerically obtain the solutions. In this case, the dynamical behaviors of the
generalization error are non-monotonic. The smaller the learning rate is, the
larger the number of teachers is; and the more variety the ensemble teachers
have, the smaller the minimum value of the generalization error is.Comment: 13 pages, 9 figure
Deformation of Equilibrium Shape of a Vesicle Induced by Injected Flexible Polymers
Using field theoretic approach, we study equilibrium shape deformation of a
vesicle induced by the presence of enclosed flexible polymers, which is a
simple model of drug delivery system or endocytosis. To evaluate the total free
energy of this system, it is necessary to calculate the bending elastic energy
of the membrane, the conformation entropy of the polymers and their
interactions. For this purpose, we combine phase field theory for the membrane
and self-consistent field theory for the polymers. Simulations on this coupled
model system for axiosymmetric shapes show a shape deformation of the vesicle
induced by introducing polymers into it. We examined the dependence of the
stability of the vesicle shape on the chain length of the polymers and the
packing ratio of the vesicle. We present a simple model calculation that shows
the relative stability of the prolate shape compared to the oblate shape.Comment: 5 pages, 3 figure
Genome Comparison and Phylogenetic Analysis of Orientia tsutsugamushi Strains
Orientia tsutsugamushi (OT) is an obligate intracellular bacterium belonging to the family Rickettsiaceae and is the causative agent of scrub typhus, or Tsutsugamushi disease. The complete genome sequences of two OT strains (Boryong and Ikeda) have recently been determined. In the present study, we performed a fine genome sequence comparison of these strains. Our results indicate that although the core gene set of the family Rickettsiaceae is highly conserved between the two strains, a common set of repetitive sequences have been explosively amplified in both genomes. These amplified repetitive sequences have induced extensive genome shuffling and duplications and deletions of many genes. On the basis of the results of the genome sequence comparison, we selected 11 housekeeping genes and carried out multilocus sequence analysis of OT strains using the nucleotide sequences of these genes. This analysis revealed for the first time the phylogenetic relationships of representative OT strains. Furthermore, the results suggest the presence of an OT lineage with higher potential for virulence, which may explain the clinical and epidemiological differences between ‘classic’ and ‘new’ types of Tsutsugamushi disease in Japan
Monte Carlo and molecular dynamics studies for the colour rewritable films
The structure of the developers plays an important role in the colouring/decolouring
process for the colour rewritable films. We study the chain-like
polymers structure of the developer through both the Monte Carlo and
molecular dynamics simulations. In these simulations we focus our attention
on the thermal (temperature) effects as well as the effective interaction
between developers (chain-like polymers), and with these how the lamellar
structure can be constructed when the system is quenched from high
temperature (low density) to low temperature (high density). We found the
transition of the states from a disordered state to an aggregated state at
a temperature (282 K). We obtained the lamellar structure in a preferable
condition of the potential parameter, while in either smaller or larger interactions,
it is rather difficult for the developer chains to form lamellar structures.Структура проявників відіграє важливу роль в процесі забарвлення/знебарвлення для кольорових записуючих плівок. Ми вивчаємо ланцюжковоподібну полімерну структуру проявника методом Монте Карло і молекулярної динаміки. В цих моделюваннях ми зосереджуємо увагу як на термічних (температурних) ефектах так і на ефективній взаємодії між проявниками (ланцюжково подібними полімерами)
і на тому як шарувата структура може бути сконструйована, коли система є різко охолоджена від високої температури (низької густини) до низької температури (високої густини). Ми знайшли перехід станів з невпорядкованого стану до агрегатного стану при температурі (282 К). Ми отримали шарувату структуру при певній умові потенціального параметра, тоді як при слабких і сильних взаємодіях шарувата структура проявника формується важко
Duodenal gastric metaplasia and Helicobacter pylori infection in patients with diffuse nodular duodenitis
- …