Photon correlation in GaAs self-assembled quantum dots

We report on photon coincidence measurement in a single GaAs self-assembled quantum dot (QD) using a pulsed excitation light source. At low excitation, when a neutral exciton line was present in the photoluminescence (PL) spectrum, we observed nearly perfect single photon emission from an isolated QD at 670 nm wavelength. For higher excitation, multiple PL lines appeared on the spectra, reflecting the formation of exciton complexes. Cross-correlation functions between these lines showed either bunching or antibunching behavior, depending on whether the relevant emission was from a biexciton cascade or a charged exciton recombination.Comment: 5 pages, 3 figure

Mutation Analysis of 2009 Pandemic Influenza A(H1N1) Viruses Collected in Japan during the Peak Phase of the Pandemic

BACKGROUND: Pandemic influenza A(H1N1) virus infection quickly circulated worldwide in 2009. In Japan, the first case was reported in May 2009, one month after its outbreak in Mexico. Thereafter, A(H1N1) infection spread widely throughout the country. It is of great importance to profile and understand the situation regarding viral mutations and their circulation in Japan to accumulate a knowledge base and to prepare clinical response platforms before a second pandemic (pdm) wave emerges. METHODOLOGY: A total of 253 swab samples were collected from patients with influenza-like illness in the Osaka, Tokyo, and Chiba areas both in May 2009 and between October 2009 and January 2010. We analyzed partial sequences of the hemagglutinin (HA) and neuraminidase (NA) genes of the 2009 pdm influenza virus in the collected clinical samples. By phylogenetic analysis, we identified major variants of the 2009 pdm influenza virus and critical mutations associated with severe cases, including drug-resistance mutations. RESULTS AND CONCLUSIONS: Our sequence analysis has revealed that both HA-S220T and NA-N248D are major non-synonymous mutations that clearly discriminate the 2009 pdm influenza viruses identified in the very early phase (May 2009) from those found in the peak phase (October 2009 to January 2010) in Japan. By phylogenetic analysis, we found 14 micro-clades within the viruses collected during the peak phase. Among them, 12 were new micro-clades, while two were previously reported. Oseltamivir resistance-related mutations, i.e., NA-H275Y and NA-N295S, were also detected in sporadic cases in Osaka and Tokyo

Ex Vivo Expansion of Human CD8+ T Cells Using Autologous CD4+ T Cell Help

Background: Using in vivo mouse models, the mechanisms of CD4+ T cell help have been intensively investigated. However, a mechanistic analysis of human CD4+ T cell help is largely lacking. Our goal was to elucidate the mechanisms of human CD4+ T cell help of CD8+ T cell proliferation using a novel in vitro model. Methods/Principal Findings: We developed a genetically engineered novel human cell-based artificial APC, aAPC/mOKT3, which expresses a membranous form of the anti-CD3 monoclonal antibody OKT3 as well as other immune accessory molecules. Without requiring the addition of allogeneic feeder cells, aAPC/mOKT3 enabled the expansion of both peripheral and tumor-infiltrating T cells, regardless of HLA-restriction. Stimulation with aAPC/mOKT3 did not expand Foxp3+ regulatory T cells, and expanded tumor infiltrating lymphocytes predominantly secreted Th1-type cytokines, interferon-γ and IL-2. In this aAPC-based system, the presence of autologous CD4+ T cells was associated with significantly improved CD8+ T cell expansion in vitro. The CD4+ T cell derived cytokines IL-2 and IL-21 were necessary but not sufficient for this effect. However, CD4+ T cell help of CD8+ T cell proliferation was partially recapitulated by both adding IL-2/IL-21 and by upregulation of IL-21 receptor on CD8+ T cells. Conclusions: We have developed an in vitro model that advances our understanding of the immunobiology of human CD4+ T cell help of CD8+ T cells. Our data suggests that human CD4+ T cell help can be leveraged to expand CD8+ T cells in vitro

HYDROSTATIC PRESSURE EFFECTS ON MUSCLE IN THE TADPOLE TAIL

It is very important to know the critical pressure which causes a living body to bring about histological damage or destructive metabolism when the hyperbaric effect is studied. Therefore, a histological examination was made on hydrostatic pressure effect on the muscle in the tadpole tail of the bullfrog (Rana catesbiana) by using an animal chamber which is able to compress a liquid from 1 to 500 atmospheric absolute (ATA). More than 200 tadpoles were compressed at the different depth of pressure between 7 and 500 ATA. The results of the experiment may be summarized as follows: (1) The　interstices between the muscular fibers are found at above 50 ATA for 10 minutes, and at 500 A TA for 30 seconds. (2) Stiffness is seen at 500 A TA for 60 seconds or over. (3) The "rounding fibers" are often found by exposure to 100 AT A for 10 minutes, and more often found at over 300 ATA. (4) The macroscopic stiffness is due to the histological "rounding fibers". (5) The damage to the muscle is caused more by decompression than by the compression effect

EVALUATION OF DIFFERENT DECOMPRESSION TABLES BY AGAROSE GEL METHOD

Nine different decompression tables were evaluated by the method of bubble formation in the agarose gel, the result of which is summarized as follows: 1) The number of bubbles formed in the agarose gel corresponded well with the exposed pressure. 2) The technique of this method was simple and the number of bubbles was accurately counted. 3) This method was considered useful for examining the decompression tables. 4) Using an equation obtained from the experiment with the same agarose gel, the critical number of bubbles at the encl of decompression was found to be 6.6. 5) From this point of view, the R.N.P.L. Table of England and Mano’s Model I Table were considered to be excellent. 6) The first stop at the deeper level during the ascent resulted in a smaller number of bubbles at the end of decompression, indicating the effectiveness of this procedure for the prevention of decompression sickness

ACUTE DECOMPRESSION SICKNESS -REPORT OF AN AUTOPSY CASE-

An autopsy case of acute decompression sickness is reported. A 45-year-old fisherman was affected after diving 10 times 35 meters below the sea and died 30 hours after the disease developed. By autopsy, wide infarcts were found in the spinal cord, lung, heart and colon

EVALUATION OF STANDARD DECOMPRESSION SCHEDULE BY AGAROSE GEL METHOD

The Standard Decompression Schedule was evaluated by the method of bubble formation in agarose gel, the result of which can be summarized as folows: 1) The number of bubbles formed in agarose gel corresponded well with the exposed pressure. 2) The technique of this method was simple and the number of bubbles was accurately counted. 3) Eventually, this method was useful for examining the decompression schedules. 4) It is not always safe to follow the Standard Decmopression Schedule in some pressure conditions. 5) As to the period of time that a person is able to tolerate a high pressure condition, the prescription of the Standard Decompression Schedule is not necessarily correct. 6) The number of bubbles was small by the proper decompression schedule, for example, in the cases of exposure above the 60-meter depth of water. 7) This method can be applied for the prevention of decompression sickness when the agarose gel samples are attached to the workers during the compressed air work. 8) The number of bubbles was inconsistent with the coefficient of body pressure (1. N2 in the body), therefore it is not necessarily safe to rely only on the coefficient of body pressure. 9) To prevent osteonecrosis, the Standard Decompression Schedule is not proper, a deeper first stop and slower ascent being recommended