NUMERICAL SIMULATION OF ASTROPHYSICAL JETS: INTERACTION WITH SURROUNDING MEDIUM

WOS: 000412307300014Propagation of astrophysical jets inside an ambient medium transports a large amount of energy to surrounding materials as a consequence of interactions. These interactions have a crucial effect on the evolution and dynamics of the jets. They can cause the formation of the jet's head, which dissipates its energy. In this paper, we have numerically modeled the evolution of jet's dynamics to understand the effects of the critical parameters (Mach numbers, jet velocity, densities, pressures of the accelerated the jet and medium, sound speeds, and Lorentz factor) on the head of the jet, jet-cocoon, vortexes and shocks. When the jet propagates inside the overdense region, we observe clear evidence for deceleration of the jet and find a more complex structure. In the underdense cases, almost no back-flows and cocoons are developed. We have also modeled the pulsed type jets propagating into the overdense region and found a very rich internal structure of the jet, such as cocoon, knots, vortexes, etc. They could explain the structure of jets seen in Herbig-Haro bows and XZ Tauri proto-jet

The Joint Impact of Fading Severity, Rotation Angle, and Non-Gaussian Noise on Signal Space Diversity-Based Relaying Networks

This work focuses on the interplay between rotation angle, transmit power, fading severity, and noise impairment severity in signal space diversity-based three time-slot decode-and-forward two-way relaying networks. Specifically, we develop a joint design for rotation angle selection and transmit power allocation, while taking into account the performance impact of fading severities on the channels and noise impairment severities on the receivers. To model different severities of fading and noise impairment, Nakagami distribution and additive non-Gaussian noise are used respectively. The objective in doing so is to promote the reliable reception of end-sources, while satisfying individual and total power budgets as well as average error probability. To this end, we start by deriving average error probabilities of end-sources for non-uniform constellations, which capture all possible signal constellations produced by using various rotation angles. Next, we formulate the joint design problem in an optimization form. Unfortunately, the resulting formulation is a non-convex optimization. To find the solution, we resort to numerical optimization. The numerical results not only validate the derived error probability expressions, but also demonstrate the efficacy of the proposed framework and provide useful insights on the interaction between rotation angle, transmit power, fading severities of the channels, and noise impairment severities at the end-sources.Peer reviewe

Comparison of 1- and 2-week pantoprazole-based triple therapies in clarithromycin-sensitive and resistant cases

Background: The objectives of this prospective study were: (i) to compare the efficacy of 1-week with 2-week pantoprazole-based triple therapy and (ii) to evaluate the impact of clarithromycin resistance on Helicobacter pylori (H. pylori) eradication rates. Methods: Eighty dyspeptic patients were randomly allocated to two groups. The first group (PAC-1, n = 40) received pantoprazole 40 mg, amoxicillin 1000 mg, and clarithromycin 500 mg twice a day for one week, and the second group (PAC-2, n = 40) received the same regimen for two weeks. Endoscopy was repeated one month after the end of the treatment. Results: DNA extraction for clarithromycin resistance could not be performed in seven cases. Five cases were lost to follow-up. Clarithromycin resistance was found to be 44.1% (15/34) in the PAC-1 group and 58.8% (20/34) in the PAC-2 group (p > 0.05). Eradication was achieved in 16 (PP: 47.1%, ITT: 44.4%) and 25 (PP:73.5%, ITT: 67.6%) patients in the PAC-1 and PAC-2 groups, respectively (p > 0.05). H. pylori was eradicated in 4 of 15 (PP: 26.7%, ITT: 26.7%) clarithromycin-resistant patients in the PAC-1 group and in 12 of 20 (PP: 60%, ITT: 60%) clarithromycin-resistant patients in the PAC-2 group (p > 0.05). Among the clarithromycin-sensitive ones, eradication was achieved in 12 of 19 (PP: 63.2%, ITT: 57.1%) patients in the PAC-1 group and in 13 of 14 (PP: 92.8%, ITT: 76.5%) patients in the PAC-2 group (p > 0.05). Conclusion: Although the 2-week regimen of pantoprazole-based triple therapy was effective for H. pylori eradication in clarithromycin-sensitive cases, highly effective H. pylori eradication protocols are needed for clarithromycin-resistant ones. © 2007 European Federation of Internal Medicine

Results of endoscopic management of anastomotic biliary strictures after orthotopic liver transplantation

PubMed ID: 16941247Background/aims: Anastomotic biliary strictures are common biliary complications after orthotopic liver transplantation. We assessed the success of endoscopic retrograde cholangio-pancreaticography (ERCP) in the treatment and outcome of post-liver transplantation anastomotic biliary strictures in a university hospital, retrospectively. Methods: Thirty-three ERCPs were performed in 20 of 162 adult liver transplant recipients with duct to duct anastomosis. Results: In five patients, ERCP failed because the stricture could not be passed with guidewire. Four patients were treated with balloon dilatation only; two of them are recurrence-free with a follow-up of 24 and 8 months. Eleven patients had balloon dilatation and plastic stent placement as their primary treatment modality. In six of them, the anastomosis remained patent for the rest of the follow-up (22 ± 13 months). Five patients had stricture recurrence after first stenting which necessitated re-stenting; four of them required a third, and three had a fourth stenting. Conclusions: Endoscopic balloon dilatation and stenting are safe and effective means of treatment of anastomotic biliary strictures following liver transplantation

Living donor liver transplantation for hepatitis B cirrhosis.

11th Annual Meeting of the International-Liver-Transplant-Society -- JUL 20-23, 2005 -- Los Angeles, CAWOS: 000230158500277Int Liver Transplant So