802 research outputs found
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
Oral vinorelbine and cisplatin with concomitant radiotherapy in stage III non-small cell lung cancer (NSCLC): A feasibility study
Background: Concurrent chemoradiotherapy has improved survival in inoperable stage III non-small cell lung cancer (NSCLC). This phase I trial was performed in order to establish a dose recommendation for oral vinorelbine in combination with cisplatin and simultaneous radiotherapy. Patients and Methods: Previously untreated patients with stage IIIB NSCLC received concurrent chemoradiotherapy with 66 Gy and 2 cycles of cisplatin and oral vinorelbine which was administered at 3 different levels (40, 50 and 60 mg/m(2)). This was to be followed by 2 cycles of cisplatin/vinorelbine oral consolidation chemotherapy. The study goal was to determine the maximal recommended dose of oral vinorelbine during concurrent treatment. Results: 11 stage IIIB patients were entered into the study. The median radiotherapy dose was 66 Gy. Grade 3-4 toxicity included neutropenia, esophagitis, gastritis and febrile neutropenia. The dose-limiting toxicity for concurrent chemoradiotherapy was esophagitis. 9 patients received consolidation chemotherapy, with neutropenia and anemia/thrombocytopenia grade 3 being the only toxicities. The overall response was 73%. Conclusion: Oral vinorelbine 50 mg/m(2) (days 1, 8, 15 over 4 weeks) in combination with cisplatin 20 mg/m2 (days 1-4) is the recommended dose in combination with radiotherapy (66 Gy) and will be used for concurrent chemoradiotherapy in a forthcoming phase III trial testing the efficacy of consolidation chemotherapy in patients not progressing after chemoradiotherapy
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, 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 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
Privacy issues and protection in secure data outsourcing
Utilizing database encryption to safeguard data in several conditions where access control is not sufficient is unavoidable. Database encryption offers an extra layer of security to traditional access control methods. It stops users that are unauthorized, such as hackers breaking into a system, and observing private data. Consequently, data is safe even when the database is stolen or attacked. Nevertheless, the process of data decryption and encryption causes degradation in the database performance. In conditions where the entire information is kept in an encrypted format, it is not possible to choose the database content any longer. The data must be first decrypted, and as such, the unwilling and forced tradeoff occurs between the function and the security. The suitable methods to improve the function are techniques that directly deal with the data that is encrypted without having to decrypt them first. In this study, we determined privacy protection and issues that each organization should consider when it decides to outsource own data
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
Motion-Induced Magnetic Resonance of Rb Atoms in a Periodic Magnetostatic Field
We demonstrate that transitions between Zeeman-split sublevels of Rb atoms
are resonantly induced by the motion of the atoms (velocity: about 100 m/s) in
a periodic magnetostatic field (period: 1 mm) when the Zeeman splitting
corresponds to the frequency of the magnetic field experienced by the moving
atoms. A circularly polarized laser beam polarizes Rb atoms with a velocity
selected using the Doppler effect and detects their magnetic resonance in a
thin cell, to which the periodic field is applied with the arrays of parallel
current-carrying wires.Comment: 4 pages, 4 figures; minor corrections, Ref. [9] removed, published in
PR
Radial compression of protons and H3+ ions in a multiring trap for the production of ultralow energy antiproton beams
Electron cooling of high-energy protons in a multiring trap with a tank circuit monitoring the electron-plasma oscillations
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 (Îł-GCS), the rate limiting enzyme in de novo synthesis of GSH, were generated through targeted gene disruption thus demonstrating, quite unexpectedly, that Îł-GCS is not essential for blood stage development. Despite a significant reduction in GSH levels, blood stage forms of pbggcsâ 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 pbggcsâ 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
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