Outgassing measurement of the aluminum alloy UHV chamber

A large vacuum chamber (580 mm diameter) was fabricated from an aluminum alloy surface treated by a special process normally used on small chambers. The chamber was tested unbaked and baked at various temperatures, pressures, and holding periods. The chamber was filled with N2 gas, and the outgassing rate was measured after one hour. Then the ultimate pressure was measured. Outgassing rates for baked and unbaked groups were compared. It is concluded that the same surface treatment technique can be used on both large and small chambers produced by the same special extrusion process

Simulations of Protoplanetary Disk Dispersal: Stellar Mass Dependence of the Disk Lifetime

Recent infrared and submillimeter observations suggest that the protoplanetary disk lifetime depends on the central stellar mass. The disk dispersal is thought to be driven by viscous accretion, magneto-hydrodynamics (MHD) winds, and photoevaporation by the central star. We perform a set of one-dimensional simulations of long-term disk evolution that include all the three processes. We vary the stellar mass in the range of 0.5-7M$_{\odot}$, and study the mass dependence of the disk evolution. We show that a significant fraction of the disk gas is lost by MHD winds in the early stage, but the later disk evolution is mainly governed by photoevaporation. The disk radius decreases as photoevaporation clears out the gas in the outer disk efficiently. The qualitative evolutionary trends of the disk mass are remarkably similar for the wide range of the central stellar mass we consider, and the time evolution of the disk mass can be well fitted by a simple function. The dispersal time is approximately ten million years for low mass stars with weak mass dependence, but gets as short as two million years around a 7M$_{\odot}$ star. In the latter case, a prominent inner hole is formed by the combined effect of accretion and MHD winds within about one million years. The strength of the MHD wind and viscous accretion controls the overall mass-loss rate, but does not alter the dependence of the dispersal timescale on the central stellar mass.Comment: 14 pages, 10 figures, 1 tabl

Channeling Effects in Direct Dark Matter Detectors

The channeling of the ion recoiling after a collision with a WIMP changes the ionization signal in direct detection experiments, producing a larger signal than otherwise expected. We give estimates of the fraction of channeled recoiling ions in NaI (Tl), Si and Ge crystals using analytic models produced since the 1960's and 70's to describe channeling and blocking effects. We find that the channeling fraction of recoiling lattice nuclei is smaller than that of ions that are injected into the crystal and that it is strongly temperature dependent.Comment: 8 pages, 12 figures, To appear in the Proceedings of the sixth International Workshop on the Dark Side of the Universe (DSU2010) Leon, Guanajuato, Mexico 1-6 June 201

Energy loss of channeled 290 MeV/u C 6 ions in a Si crystal

Abstract We have succeeded in observing the channeling of 290 MeV/u C 6 ions in a Si crystal. Under h1 1 0i axial, and (0 0 4), 2 2 0 and 1 1 1 planar channeling conditions, energy loss of the channeled ion in the Si crystal was observed. We also calculated the trajectory dependent stopping power for planar channeling ions, which employs mean and local electron densities evaluated adopting the Moli ere potential. Calculated energy loss spectra were found to reproduce the experimental results quite well. Ó 1998 Elsevier Science B.V

The glutathione biosynthetic pathway of Plasmodium is essential for mosquito transmission

1Infection of red blood cells (RBC) subjects the malaria parasite to oxidative stress. Therefore, efficient antioxidant and redox systems are required to prevent damage by reactive oxygen species. Plasmodium spp. have thioredoxin and glutathione (GSH) systems that are thought to play a major role as antioxidants during blood stage infection. In this report, we analyzed a critical component of the GSH biosynthesis pathway using reverse genetics. Plasmodium berghei parasites lacking expression of gamma-glutamylcysteine synthetase (γ-GCS), the rate limiting enzyme in de novo synthesis of GSH, were generated through targeted gene disruption thus demonstrating, quite unexpectedly, that γ-GCS is not essential for blood stage development. Despite a significant reduction in GSH levels, blood stage forms of pbggcs− parasites showed only a defect in growth as compared to wild type. In contrast, a dramatic effect on development of the parasites in the mosquito was observed. Infection of mosquitoes with pbggcs− parasites resulted in reduced numbers of stunted oocysts that did not produce sporozoites. These results have important implications for the design of drugs aiming at interfering with the GSH redox-system in blood stages and demonstrate that de novo synthesis of GSH is pivotal for development of Plasmodium in the mosquito

Genetic Variants in Inflammation-Related Genes Are Associated with Radiation-Induced Toxicity Following Treatment for Non-Small Cell Lung Cancer

Treatment of non-small cell lung cancer (NSCLC) with radiotherapy or chemoradiotherapy is often accompanied by the development of esophagitis and pneumonitis. Identifying patients who might be at increased risk for normal tissue toxicity would help in determination of the optimal radiation dose to avoid these events. We profiled 59 single nucleotide polymorphisms (SNPs) from 37 inflammation-related genes in 173 NSCLC patients with stage IIIA/IIIB (dry) disease who were treated with definitive radiation or chemoradiation. For esophagitis risk, nine SNPs were associated with a 1.5- to 4-fold increase in risk, including three PTGS2 (COX2) variants: rs20417 (HR:1.93, 95% CI:1.10–3.39), rs5275 (HR:1.58, 95% CI:1.09–2.27), and rs689470 (HR:3.38, 95% CI:1.09–10.49). Significantly increased risk of pneumonitis was observed for patients with genetic variation in the proinflammatory genes IL1A, IL8, TNF, TNFRSF1B, and MIF. In contrast, NOS3:rs1799983 displayed a protective effect with a 45% reduction in pneumonitis risk (HR:0.55, 95% CI:0.31–0.96). Pneumonitis risk was also modulated by polymorphisms in anti-inflammatory genes, including genetic variation in IL13. rs20541 and rs180925 each resulted in increased risk (HR:2.95, 95% CI:1.14–7.63 and HR:3.23, 95% CI:1.03–10.18, respectively). The cumulative effect of these SNPs on risk was dose-dependent, as evidenced by a significantly increased risk of either toxicity with an increasing number of risk genotypes (P<0.001). These results suggest that genetic variations among inflammation pathway genes may modulate the development of radiation-induced toxicity and, ultimately, help in identifying patients who are at an increased likelihood for such events

Treatment of squamous cell carcinoma of the uterine cervix with radiation therapy alone: long-term survival, late complications, and incidence of second cancers

The objective of this retrospective study was to determine the survival rate, incidence of late complications, and incidence of second cancers when radiation therapy alone is used for carcinoma of the uterine cervix. Between 1971 and 1995, 1495 patients with squamous cell carcinoma of the uterine cervix (stages I–IV) were treated with radiation therapy alone in our hospital. Radiation therapy consisted of a combination of high-dose-rate intracavitary brachytherapy and external beam radiotherapy. The cumulative 5-year survival rates for stages Ib, II, and III/IVa carcinoma were 93.5, 77.0, and 60.3%, respectively, and the 10-year survival rates were 90.9, 74.5, and 56.1%, respectively. Local control rates for stages Ib, II, and III/IVa carcinoma were 92.0, 79.4 and 64.2%, respectively. Eighty-two (5.5%) patients suffered grade III/IV or V (fatal) complications. A second cancer developed in 13 (0.87%) patients. Second cancers were observed most frequently in the rectum (five cases), colon (three cases), and uterine body (two cases). Long-term follow-up data revealed that our method of radiation therapy alone for locally advanced carcinoma of the uterine cervix is effective, with low incidences of late complications and second cancers