Fluctuations of radiation from a chaotic laser below threshold

Radiation from a chaotic cavity filled with gain medium is considered. A set of coupled equations describing the photon density and the population of gain medium is proposed and solved. The spectral distribution and fluctuations of the radiation are found. The full noise is a result of a competition between positive correlations of photons with equal frequencies (due to stimulated emission and chaotic scattering) which increase fluctuations, and a suppression due to interaction with a gain medium which leads to negative correlations between photons. The latter effect is responsible for a pronounced suppression of the photonic noise as compared to the linear theory predictions.Comment: 7 pages, 5 figures; expanded version, to appear in Phys. Rev.

Revisional laparoscopic parastomal hernia repair

Background: We herein report a laparoscopically performed re-do operation on a patient who had previously undergone a laparoscopic parastomal hernia repair. Case Report: We describe the case of a 71-year-old patient who presented within 3 months of her primary laparoscopic parastomal hernia repair with recurrence. On relaparoscopy, dense adhesions to the mesh were found, and the mesh had migrated into the hernia sac. This had allowed loops of small bowel to herniate into the sac. The initial part of the procedure involved the lysis of adhesions. A piece of Gore-Tex DualMesh with a central keyhole and a radial slit was cut so that it could provide at least 3 cm to 5 cm of overlap of the fascial defect. The tails of the mesh were wrapped around the bowel, and the mesh was secured to the margins of the hernia with circumferential metal tacking and 4 transfascial sutures. The patient remains in satisfactory condition and no recurrence or any surgery-related problem has been observed during 8 months of follow-up. Conclusion: Revisional laparoscopic repair of parastomal hernias seems feasible and has been shown to be safe and effective in this case. The success of this approach depends on longer follow-up reports and standardization of the technical elements

Theory for the photon statistics of random lasers

A theory for the photon statistics of a random laser is presented. Noise is described by Langevin operators, where both fluctuations of the electromagnetic field and of the medium are included. The theory is valid for all lasers with small outcoupling when the laser cavity is large compared to the wavelength of the radiation. The theory is applied to a chaotic laser cavity with a small opening. It is known that a large number of modes can be above threshold simultaneously in such a cavity. It is shown the amount of fluctuations is increased compared to the Poissonian value by an amount that depends on that number

High-intensity-focused ultrasound in the treatment of primary prostate cancer: the first UK series

BACKGROUND: The use of minimally invasive ablative therapies in localised prostate cancer offer potential for a middle ground between active surveillance and radical therapy. METHODS: An analysis of men with organ-confined prostate cancer treated with transrectal whole-gland HIFU (Sonablate 500) between 1 February 2005 and 15 May 2007 was carried out in two centres. Outcome data (side-effects using validated patient questionnaires, biochemical, histology) were evaluated. RESULTS: A total of 172 men were treated under general anaesthetic as day-case procedures with 78% discharged a mean 5 h after treatment. Mean follow-up was 346 days (range 135-759 days). Urethral stricture was significantly lower in those with suprapubic catheter compared with urethral catheters (19.4 vs 40.4%, P = 0.005). Antibiotics were given to 23.8% of patients for presumed urinary tract infection and the rate of epididymitis was 7.6%. Potency was maintained in 70% by 12 months, whereas mild stress urinary incontinence (no pads) was reported in 7.0% (12 out of 172) with a further 0.6% (1 out of 172) requiring pads. There was no rectal toxicity and no recto-urethral fistulae. In all, 78.3% achieved a PSA nadir <= 0.5 mu g ml(-1) at 12 months, with 57.8% achieving <= 0.2 mu g ml(-1). Then, 8 out of 13 were retreated with HIFU, one had salvage external beam radiotherapy and four chose active surveillance for small-volume low-risk disease. Overall, there was no evidence of disease (PSA <0.5 mu g ml(-1) or negative biopsy if nadir not achieved) after one HIFU session in 92.4% ( 159 out of 172) of patients. CONCLUSION: HIFU is a minimally invasive, day-case ablative technique that can achieve good biochemical outcomes in the short term with minimal urinary incontinence and acceptable levels of erectile dysfunction. Long-term outcome needs further evaluation and the inception of an international registry for cases treated using HIFU will significantly aid this health technology assessment. British Journal of Cancer (2009) 101, 19-26. doi: 10.1038/sj.bjc.6605116 www.bjcancer.com Published online 9 June 2009 (C) 2009 Cancer Research U

The G1613A Mutation in the HBV Genome Affects HBeAg Expression and Viral Replication through Altered Core Promoter Activity

Infection of hepatitis B virus (HBV) causes acute and chronic hepatitis and is closely associated with the development of cirrhosis and hepatocellular carcinoma (HCC). Previously, we demonstrated that the G1613A mutation in the HBV negative regulatory element (NRE) is a hotspot mutation in HCC patients. In this study, we further investigated the functional consequences of this mutation in the context of the full length HBV genome and its replication. We showed that the G1613A mutation significantly suppresses the secretion of e antigen (HBeAg) and enhances the synthesis of viral DNA, which is in consistence to our clinical result that the G1613A mutation associates with high viral load in chronic HBV carriers. To further investigate the molecular mechanism of the mutation, we performed the electrophoretic mobility shift assay with the recombinant RFX1 protein, a trans-activator that was shown to interact with the NRE of HBV. Intriguingly, RFX1 binds to the G1613A mutant with higher affinity than the wild-type sequence, indicating that the mutation possesses the trans-activating effect to the core promoter via NRE. The trans-activating effect was further validated by the enhancement of the core promoter activity after overexpression of RFX1 in liver cell line. In summary, our results suggest the functional consequences of the hotspot G1613A mutation found in HBV. We also provide a possible molecular mechanism of this hotspot mutation to the increased viral load of HBV carriers, which increases the risk to HCC

Varieties of export-oriented entrepreneurship in Asia

This paper explores differences in the proportion of export-oriented early-stage entrepreneurial activity in 12 Asian countries. Drawing on varieties of capitalism theory, we find that Asian countries with high quality institutions are more likely to have higher proportions of young export-oriented firms. However, analysis on a 51 country data set indicates that Asian countries have significantly fewer young export-oriented firms than do non-Asian countries. Furthermore, the multi-country study reveals that countries with higher proportions of export-oriented entrepreneurial activity tend to have flexible industrial relations, high quality vocational training, and confrontational labor-employer relations, however the proportion of export-oriented new ventures is not related to the quality of corporate governance and inter-firm relations