Temporal characterization of harmonic radiation generated by intense laser-plasma interaction

Attosecond physics has become one of the most thriving field of science over the last decade. Although high-order harmonic generation from gaseous media is widely used as the source of attosecond pulses, a demand for more intense coherent extreme ultraviolet (XUV) and soft x-ray (SXR) radiation sources is growing. The process of high-order harmonic generation from plasma surfaces has attracted a strong interest as a promising candidate to meet this demand. Despite many theoretical predictions of the possibilities to generate intense attosecond pulses, experimental verifications are yet to come. The main theme of this thesis is to characterize the temporal structure of the harmonics generated from plasma surfaces. To achieve this goal, several preparatory experiments are made first. The contrast of the laser pulse is one of the most critical parameters for the harmonic generation process and its improvement is demonstrated by using a plasma mirror. The properties of the generated harmonics are studied thoroughly to find the optimal condition for temporal characterization. These experiments provide the groundwork for the autocorrelation measurements of the pulse train. To characterize the temporal structure of the generated harmonics, the technique of the volume autocorrelation using two-photon ionization of helium is applied. The measured autocorrelation traces reveal attosecond structures within the XUV radiation generated from the plasma surfaces for the first time. The observation of attosecond structures prove the potential of this harmonic generation process as a source of attosecond pulses. The process holds a promise to generate attosecond pulses with unprecedented intensities, which will open up a new regime of attosecond physics

Level spectroscopy of the square-lattice three-state Potts model with a ferromagnetic next-nearest-neighbor coupling

We study the square-lattice three-state Potts model with the ferromagnetic next-nearest-neighbor coupling at finite temperature. Using the level-spectroscopy method, we numerically analyze the excitation spectrum of the transfer matrices and precisely determine the global phase diagram. Then we find that, contrary to a previous result based on the finite-size scaling, the massless region continues up to the decoupling point with ${\bf Z}_3\times{\bf Z}_3$ criticality in the antiferromagnetic region. We also check the universal relations among excitation levels to provide the reliability of our result.Comment: 4 pages, 2 figure

Metabolism of a Glycosaminoglycan during Metamorphosis in the Japanese Conger eel, Conger myriaster

Hyaluronan (HA) is a linear polysaccharide of high molecular weight that exists as a component of the extracellular matrix. The larvae (leptocephali) of the Japanese conger eel (Anguilliformes: Conger myriaster) have high levels of hyaluronan (HA) which is thought to help control body water content. We isolated glycosaminoglycans (GAGs) from Japanese conger eel leptocephali and measured the changes in tissue HA content during metamorphosis. HA content decreased during metamorphosis. In contrast, neutral sugar content increased during metamorphosis. We hypothesize that the leptocephali utilize a metabolic pathway that converts HA to glucose during metamorphosis. Glucose may then be metabolized to glycogen and stored in the juvenile life-history stage

Ground state of an S=1/2S=1/2 distorted diamond chain - model of Cu3Cl6(H2O)2⋅2H8C4SO2\rm Cu_3 Cl_6 (H_2 O)_2 \cdot 2H_8 C_4 SO_2

We study the ground state of the model Hamiltonian of the trimerized $S=1/2$ quantum Heisenberg chain $\rm Cu_3 Cl_6 (H_2 O)_2 \cdot 2H_8 C_4 SO_2$ in which the non-magnetic ground state is observed recently. This model consists of stacked trimers and has three kinds of coupling constants between spins; the intra-trimer coupling constant $J_1$ and the inter-trimer coupling constants $J_2$ and $J_3$. All of these constants are assumed to be antiferromagnetic. By use of the analytical method and physical considerations, we show that there are three phases on the $\tilde J_2 - \tilde J_3$ plane ($\tilde J_2 \equiv J_2/J_1$, $\tilde J_3 \equiv J_3/J_1$), the dimer phase, the spin fluid phase and the ferrimagnetic phase. The dimer phase is caused by the frustration effect. In the dimer phase, there exists the excitation gap between the two-fold degenerate ground state and the first excited state, which explains the non-magnetic ground state observed in $\rm Cu_3 Cl_6 (H_2 O)_2 \cdot 2H_8 C_4 SO_2$. We also obtain the phase diagram on the $\tilde J_2 - \tilde J_3$ plane from the numerical diagonalization data for finite systems by use of the Lanczos algorithm.Comment: LaTeX2e, 15 pages, 21 eps figures, typos corrected, slightly detailed explanation adde

Chemo-Sensitive Running Droplet

Chemical control of the spontaneous motion of a reactive oil droplet moving on a glass substrate under an aqueous phase is reported. Experimental results show that the self-motion of an oil droplet is confined on an acid-treated glass surface. The transient behavior of oil-droplet motion is also observed with a high-speed video camera. A mathematical model that incorporates the effect of the glass surface charge is built based on the experimental observation of oil-droplet motion. A numerical simulation of this mathematical model reproduced the essential features concerning confinement within a certain chemical territory of oil-droplet motion, and also its transient behavior. Our results may shed light on physical aspects of reactive spreading and a chemotaxis in living things.Comment: 17 pages, 10 figure

Efficacy of glimepiride on insulin resistance, adipocytokines, and atherosclerosis

Background : Plasma adiponectin levels increase after the administration of glimepiride. This unique effects would also be expected to improve other adipocytokines and have antiatherosclerotic action in patients with metabolic syndrome. Methods : Thirty-four patients with type 2 diabetes mellitus who were administrated glibenclamide were randomly divided into two groups. In20patients glibenclamide was changed to glimepiride (GP group), and the administration of glibenclamide (GB group) was continued in 14 patients. Twelve patients receiving insulin therapy (INS group) were enrolled for comparison. The levels of plasma adiponectin, high sensitive-CRP, TNF-α, interleukin-6, homeostasis model assessment-insulin resistance (HOMA-IR), brachial-ankle pulse wave velocity (baPWV) and augmentation index (AI) were measured before and 28 weeks after the therapy. Results: HOMA-IR in the GP group was significantly decreased compared to the GB group. Plasma adiponectin levels were significantly increased in the GP group but not in the other groups. TNF-α, interleukin-6 and high sensitive-CRP levels were significantly decreased in the GP group, but not in the other groups. The baPWV and AI levels did not change in either the GB or the INS group, but were significantly decreased in the GP group. Conclusions: Glimepiride appears to improve insulin resistance and atherosclerotic disorders

Evaluation of episodes of sleep apnea in patients with liver cirrhosis

Objective : Obstructive sleep apnea syndrome (OSAS) has been reported to be a new complication of liver cirrhosis with ascites. This fact prompted a study of episodes of sleep apnea as a function of the severity of cirrhosis. Methods : Forty eight patients with type Cliver cirrhosis were divided according to the Child- Pugh score into 3 groups : Group A (16 patients with grade A cirrhosis), Group B (16 patients with grade B cirrhosis), and Group C (16 patients with grade C cirrhosis). Portable sleep polygraphs (Fuji RC, Inc. Tokyo, Japan) were attached to the subjects, and oronasal respiration, tracheal sounds, respiratory movements of the chest, and percutaneous arterial oxygen saturation continuously were recorded. A decrease in the mean airflow to 50% or less was defined as hypopnea, and the number per hour of episodes of apnea and hypopnea per hour lasting 10 seconds or longer (AHI) was counted. A Holter ECG was also recorded, and spectral heart rate variability during sleep was analyzed by measuring low frequency power (0.04-0.15 Hz, LF power), high frequency power (0.15-0.40 Hz, HF power), the ratio of LF power to HF power (LF/HF ratio), and very low frequency power (0.008-0.04 Hz, VLF power). The difference in QT interval between the lead CM5 and the lead CM1 (QTc dispersion) was also examined. Results : AHI was significantly higher in Group C than in Groups A and B (p<0.05). In Group C, 6 patients with 20 times or more AHI per hour, obstructive sleep apnea, in which respiratory chest movements occur but oronasal respiration decreases or disappears, was observed. Spectral analyses of heart rate variability showed a decrease in HF power without sleep apnea, but increases in HF power and VLF power were observed during sleep apnea. The QTc dispersion increased during episodes of sleep apnea. Conclusions : As the stage of liver cirrhosis advanced, sleep apnea appeared, and changes in autonomic nervous activities were observed. Furthermore, QTc dispersion was increased during episodes of sleep apnea, presumably increasing the risk of ventricular arrhythmia

Nateglinide with glibenclamide examination using the respiratory quotient (RQ)

Purpose: The respiratory quotient (RQ) is useful for evaluating glucose and lipid metabolism in vivo. We previously reported that the RQ value, even after fasting, was high in diabetics being treated with sulphonylurea (SU), which might explain the accumulation of fat, leading to weight gain in such individuals. In the present study, wemeasured the RQ in type II diabetic patients who were being treated with a rapid-onset/short-duration insulinotropic agent, nateglinide, and compared it with those being treated with SU. Methods: A glucose tolerance test was performed in 20 patients with type II diabetes mellitus treated with nateglinide and in 14 patients treated with SU, and the RQ was simultaneously measured. Results : The RQ values in the patients treated with nateglinide, were similar to those in healthy adults, but was lower than in those treated with SU. No weight gain was observed in patients treated with nateglinide. Conclusion : A significant weight gain was reported in subjects treated with SU, accompanied by an increase in RQ. However, weight gain was less frequent in diabetics treated with nateglinide

Finite-size Scaling of Correlation Ratio and Generalized Scheme for the Probability-Changing Cluster Algorithm

We study the finite-size scaling (FSS) property of the correlation ratio, the ratio of the correlation functions with different distances. It is shown that the correlation ratio is a good estimator to determine the critical point of the second-order transition using the FSS analysis. The correlation ratio is especially useful for the analysis of the Kosterlitz-Thouless (KT) transition. We also present a generalized scheme of the probability-changing cluster algorithm, which has been recently developed by the present authors, based on the FSS property of the correlation ratio. We investigate the two-dimensional quantum XY model of spin 1/2 with this generalized scheme, obtaining the precise estimate of the KT transition temperature with less numerical effort.Comment: 4 pages, RevTeX4, to appear in Phys. Rev. B, Rapid Communication