Numerical and Experimental Studies on Choked Underexpanded Jets

Axisymmetric underexpanded supersonic jets are investigated numerically and experimentally. A time-dependent technique of solution is applied to solve the Euler equations for a compressible ideal gas. The characteristics of the Mach disk obtained by the numerical calculations are compared with the experiments, and a good agreement is obtained. It is shown that the numerical results are very sensitive to the choice of the boundary conditions imposed on the artificially introduced numerical boundaries. The boundary condition giving the best results is found to be the ambient gas condition. It is shown that the global jet structure with a nearly regular shock pattern, wich is stable and steady itself, is destabilized by the vortex rings (Kelvin-Helmholtz roll-up) on the jet boundary. These vortices produce shocks inside the jet, which are convected downstream with the eddies. This strongly suggests that a time-independent or a time-converged solution cannot be expected without making a suitable time-averaging of the time-dependent solutions

Smoking Cessation after Discharge among Japanese Patients with Established Ischemic Heart Disease: A Prospective Cohort Study

In this prospective cohort study for Japanese patients with established ischemic heart disease (IHD), the authors investigated the rate of success of smoking cessation 3 months after hospital discharge and its related factors. The subjects included 90 current smokers admitted for IHD. A total of 58 subjects (64%) had quit smoking for 3 months after being discharged. In comparison with subjects with acute myocardial infarction, those with stable angina (SA) showed a significantly lower frequency of smoking cessation (relative risk of resuming smoking (95% confidence interval):2.06 (1.09, 3.92), p=0.036). This relationship remained significant even after controlling for sex, age, and scores of the Fagerstrom Test for Nicotine Dependence (adjusted odds ratio:3.39 (1.01, 11.37), p=0.048). However, it became insignificant when hospital admission followed by emergency medical service (EMS) care was additionally adjusted (adjusted odds ratio:2.48 (0.36, 16.97), p=0.356). The smoking cessation rate in this study was identical to that observed in studies conducted in Japan prior to the recent social changes with regard to tobacco use. SA still appears to be a risk factor for smoking resumption after discharge. Experiencing EMS care would be an intermediate variable in this relationship.</p

Effectiveness of an erbium-doped:yttrium, aluminum and garnet laser for treatment of peri-implant disease : clinical, microbiological, and biochemical marker analyses

The effectiveness of an erbium-doped: yttrium, aluminum and garnet (Er: YAG) laser (EYL) for the treatment of peri-implant disease (PID) remains unclear. The aim of this study was to compare non-surgical EYL therapy for PID with locally delivered minocycline hydrochloride (MC) ointment therapy by evaluating clinical, microbiological, and biochemical markers. Thirty-seven patients with PID were randomly assigned to either the EYL group (n = 18) or the MC group (n = 19). The clinical, microbiological, and biochemical markers at baseline and at 1 and 3 months after treatment were compared between the two groups. Subgingival plaque and peri-implant crevicular fluid (PICF) were collected from the diseased pockets. In the EYL group, probing pocket depth (PPD) was significantly decreased after treatment when compared with baseline. On the other hand, in the MC group, there was no significant decrease in PPD after treatment. Specific bacteria associated with PID were not determined. The counts of both Gram-positive and -negative species did not significantly decrease in the EYL group at 3 months after treatment. In the MC group, the counts of almost all bacterial species were significantly decreased after treatment. Biochemical marker analysis of PICF revealed significantly lower levels of metalloproteinase (MMP)-9 in the EYL group, as compared with the MC group at 3 months after treatment (p= 0.009). Non-surgical therapy with an EYL for PID was clinically effective, with decreased MMP-9 levels in PICF, which may lead to reduced peri-implant tissue destruction

Cardiac side population cells have a potential to migrate and differentiate into cardiomyocytes in vitro and in vivo

Side population (SP) cells, which can be identified by their ability to exclude Hoechst 33342 dye, are one of the candidates for somatic stem cells. Although bone marrow SP cells are known to be long-term repopulating hematopoietic stem cells, there is little information about the characteristics of cardiac SP cells (CSPs). When cultured CSPs from neonatal rat hearts were treated with oxytocin or trichostatin A, some CSPs expressed cardiac-specific genes and proteins and showed spontaneous beating. When green fluorescent protein–positive CSPs were intravenously infused into adult rats, many more (∼12-fold) CSPs were migrated and homed in injured heart than in normal heart. CSPs in injured heart differentiated into cardiomyocytes, endothelial cells, or smooth muscle cells (4.4%, 6.7%, and 29% of total CSP-derived cells, respectively). These results suggest that CSPs are intrinsic cardiac stem cells and involved in the regeneration of diseased hearts