Diagnosis of ultrafast surface dynamics of thin foil targets irradiated by intense laser pulses.

The temporal modulation of an electron bunch train accelerated from a foil target irradiated by an intense laser pulse is studied by measuring the coherent transition radiation (CTR) from the rear surface of a target. We experimentally obtained CTR spectra from a 1 µm thick foil target irradiated at a maximum intensity of 6.5 × 1019 W/cm2. Spectral redshifts of the emitted radiation corresponding to increases in laser intensity were observed. These measurements were compared with the theoretical calculation of CTR spectra considering ultrafast surface dynamics, such as plasma surface oscillation and relativistically induced transparency. Plasma surface oscillations induce a spectral redshift, while relativistic transparency causes a spectral blueshift. Both effects are required to find reasonable agreement with the experiment over the entire range of laser intensities.

Diagnosis of warm dense conditions in foil targets heated by intense femtosecond laser pulses using Kα imaging spectroscopy.

Warm dense conditions in titanium foils irradiated with intense femtosecond laser pulses are diagnosed using an x-ray imaging spectroscopy technique. The line shapes of radially resolved titanium Kα spectra are measured with a toroidally bent GaAs crystal and an x-ray charge-coupled device. Measured spectra are compared with the K-shell emissions modeled using an atomic kinetics - spectroscopy simulation code. Kα line shapes are strongly affected by warm (5-40 eV) bulk electron temperatures and imply multiple temperature distributions in the targets. The spatial distribution of temperature is dependent on the target thickness, and a thin target shows an advantage to generate uniform warm dense conditions in a large area.

Measurement of Electron-Ion Relaxation in Warm Dense Copper.

Experimental investigation of electron-ion coupling and electron heat capacity of copper in warm and dense states are presented. From time-resolved x-ray absorption spectroscopy, the temporal evolution of electron temperature is obtained for non-equilibrium warm dense copper heated by an intense femtosecond laser pulse. Electron heat capacity and electron-ion coupling are inferred from the initial electron temperature and its decrease over 10 ps. Data are compared with various theoretical models.

Acute surgical unit safely reduces unnecessary after-hours cholecystectomy.

INTRODUCTION: The acute surgical model has been trialled in several institutions with mixed results. The aim of this study was to determine whether the acute surgical model provides better outcomes for patients with acute biliary presentation, compared with the traditional emergency surgery model of care. METHODS: A retrospective review was carried out of patients who were admitted for management of acute biliary presentation, before and after the establishment of an acute surgical unit (ASU). Outcomes measured were time to operation, operating time, after-hours operation (6pm - 8am), length of stay and surgical complications. RESULTS: A total of 342 patients presented with acute biliary symptoms and were managed operatively. The median time to operation was significantly reduced in the ASU group (32.4 vs 25.4 hours, p=0.047), as were the proportion of operations performed after hours (19.5% vs 2.5%, p<0.001) and the median length of stay (4 vs 3 days, p<0.001). The median operating time, rate of conversion to open cholecystectomy and wound infection rates remained similar. CONCLUSIONS: Implementation of an ASU can lead to objective differences in outcomes for patients who present with acute cholecystitis. In our study, the ASU significantly reduced time to operation, the number of operations performed after hours and length of stay.

Risk factors for penicillin resistance and mortality in Korean adults with Streptococcus pneumoniae bacteremia.

A retrospective analysis was performed to measure the incidence of pneumococcal bacteremia and to identify risk factors for penicillin resistance and prognostic factors for outcome in adults. A total of 151 cases of pneumococcal bacteremia were identified from 149 adults during the period 1996-2000. The overall rate of penicillin resistance was 49%, ranging from 54.2% in 1996 to 48.5% in 2000 (P=0.93). Rates of resistance to ceftriaxone, clindamycin, erythromycin, and trimethoprim-sulfamethoxazole were 21.6%, 51%, 62%, and 44.7%, respectively. Multidrug resistance was documented in 47.7% of the cases. Penicillin resistance was significantly associated with solid tumor, biliary drainage catheter, and previous beta-lactam therapy in the univariate analysis. However, the associations were not as significant as independent risk factors in the multivariate analysis. Mortality was 23.8% and did not change significantly during the study period (P=0.06). Mortality rates in cases caused by penicillin-susceptible Streptococcus pneumoniae and penicillin-resistant Streptococcus pneumoniae were 23% and 24.7%, respectively (P=0.81). Mortality was not significantly influenced by penicillin resistance, even high-level resistance (24.4% vs. 20%; P=0.64). Multivariate analysis revealed that antineoplastic chemotherapy, respiratory failure, and acute renal failure were independent prognostic factors for mortality. In conclusion, the rate of penicillin resistance among pneumococcal blood isolates was high in the late 1990s, but penicillin resistance, and even high-level penicillin resistance, was not significantly associated with increased mortality in adults with pneumococcal bacteremia.

Measurement of one-bond 1H-13C, couplings in backbone-labelled proteins.

NMR dipole-dipole couplings between protein backbone nuclei (1H(alpha), 13C(alpha), 15N, 1H(N), 13C') offer enormous scope for the rapid determination of protein global folds. Here, we show that measurement of one-bond splittings in the protein backbone is facilitated by use of protein that is selectively isotopically enriched only in the backbone atoms. In particular, 1H(alpha)-13C(alpha) couplings can be measured simply and with high sensitivity by use of conventional heteronuclear single quantum correlation (HSQC) techniques.

Coping and negative appraisal as mediators between control beliefs and psychological symptoms in children of divorce.

Examined control beliefs of children of divorce as predictors of their coping, negative appraisals for stressful events, and mental health problems. We tested whether coping and negative appraisal for stressful events mediated the relations between multiple dimensions of control beliefs and mental health problems. Different dimensions of control beliefs were related to different aspects of coping and negative stress appraisal. Internal control beliefs for positive events were related to both active and avoidant coping. Unknown control beliefs for positive events were related to higher active coping and higher negative appraisal. Unknown control beliefs for negative events were related to higher avoidant coping. In addition, evidence for mediation was found such that the effect of unknown control beliefs for positive events on mental health problems was mediated by negative appraisal. Implications and directions for further research are discussed.

Estrogen increases eNOS and NOx release in human coronary artery endothelium.

Estrogen protects against the development of coronary heart disease in women. This study was designed to examine the direct effects of estrogen on nitric oxide release and endothelial nitric oxide synthase (eNOS) expression in cultured human coronary artery endothelial cells (HCAECs). NOx (nitrate, nitrite, and nitric oxide) was measured by the chemiluminescence method. Prolonged treatment (48 h) of the cells with 17beta-estradiol (E2beta), but not 17alpha-estradiol (E2alpha), resulted in a 2.3-fold increase in basal NOx release in HCAECs and an enhanced adenosine triphosphate (ATP)- and calcium ionophore A23187-induced NOx release. The effects of E2beta on endothelial NOx release were blocked by estrogen-receptor antagonist ICI 182,780. E2beta had no effect on basal and ATP-stimulated intracellular Ca2+ concentrations in HCAECs. However, E2beta significantly increased eNOS protein levels, as determined by Western analysis. We conclude that estrogen increases NOx release in HCAECs, which is independent of cytosolic Ca2+ mobilization and is mediated by the upregulation of eNOS.