522 research outputs found
Generation of Electron Beam Plasma inside the Dielectric Tube
The results of experimental study of electron beam plasma inside the dielectric tube are presented. Beam plasma was generated by the fore-vacuum plasma electron source at (2-10) Pa in dc mode. It is shown, that the dependence of the plasma potential on gas pressure inside the tube is completely different in comparison with similar dependence without a tube. Monotonic dependence of the insulated beam col-lector potential in the tube on beam energy has two stages: slow and fast growth
A METHOD FOR THE ESTIMATION OF TSUNAMI RISK ALONG RUSSIA’s FAR EAST
A simplified method was developed for estimating the tsunami risk for a coast for possible events having recurrence periods of 50 and 100 years. The method is based on readily available seismic data and the calculation of magnitudes of events with specified return periods. A classical Gumbel statistical method was used to estimate magnitudes of small probability events. The tsunami numerical modeling study used the average earthquake coordinates in the Kuril-Kamchatka high- seismic area. The verification and testing of the method were carried out using events from the North, Middle and South Kuril Islands – the most tsunami-risk areas of Russia’s Far East. Also, the study used the regional Kuril-Kamchatka catalogue of earthquakes from 1900 to 2008 - which included earthquakes with magnitudes of at least M=6. The results of the study indicate that the proposed methodology provides reasonable estimates of tsunami risk
A description of a system of programs for mathematically processing on unified series (YeS) computers photographic images of the Earth taken from spacecraft
A description of a batch of programs for the YeS-1040 computer combined into an automated system for processing photo (and video) images of the Earth's surface, taken from spacecraft, is presented. Individual programs with the detailed discussion of the algorithmic and programmatic facilities needed by the user are presented. The basic principles for assembling the system, and the control programs are included. The exchange format within whose framework the cataloging of any programs recommended for the system of processing will be activated in the future is displayed
Optical and structural properties of the GaAs heterostructures grown using AlGaAs superlattice buffer layer on compliant Si(100) substrates with the preformed porous-Si (por-Si) layer
360 nm and 700 nm thick GaAs layers were grown by MO MOCVD growth technique directly on compliant Si (100) substrate and on supper-lattice (SL) AlGaAs buffer layer. The XRD study revealed better structural quality for the sample grown on SL / por-Si buffer. AFM study revealed a smoother sample surface with blocks of more regular rectangular shape and larger size as well. Photoluminescence spectra of the samples revealed an energy shift of PL maximum intensity for both samples. Sample grown on SL buffer also showed higher PL intensity corresponding to better crystalline perfection
An Analysis of the Chemical Composition of the Atmosphere of Venus on an AMS of the Venera-12 Using a Gas Chromatograph
Eight analyses of the atmosphere of Venus were made beginning at an altitude of 42 km right down to the surface of the planet. The following were detected in the atmosphere of Venus: nitrogen in concentrations of 2.5 plus or minus 0.5 volumetric %, argon ir concentrations (4 plus or minus 2) x 10 to the minus 3 power volumetric %, CO--(2.8 plus or minus 1.4) x 10 to the minus 3 power volumetric % and SO2 in concentrations (1.3 plus or minus 0.6) x 10 to the minus 2 power volumetric %. The upper limits were estimated for the content of oxygen and water equal to 2 x 10 to the minus 3 power and 10 to the minus 2 power volumetric %, respectively
Automated search for star clusters in large multiband surveys: II. Discovery and investigation of open clusters in the Galactic plane
Automated search for star clusters in J,H,K_s data from 2MASS catalog has
been performed using the method developed by Koposov et. al (2008). We have
found and verified 153 new clusters in the interval of the galactic latitude
-24 < b < 24 degrees. Color excesses E(B-V), distance moduli and ages were
determined for 130 new and 14 yet-unstudied known clusters. In this paper, we
publish a catalog of coordinates, diameters, and main parameters of all the
clusters under study. A special web-site available at http://ocl.sai.msu.ru has
been developed to facilitate dissemination and scientific usage of the results.Comment: 9 pages, 3 tables, 5 figures, accepted to Astronomy Letter
Size does matter: overcoming the adeno-associated virus packaging limit
Recombinant adeno-associated virus (rAAV) vectors mediate long-term gene transfer without any known toxicity. The primary limitation of rAAV has been the small size of the virion (20 nm), which only permits the packaging of 4.7 kilobases (kb) of exogenous DNA, including the promoter, the polyadenylation signal and any other enhancer elements that might be desired. Two recent reports (D Duan et al: Nat Med 2000, 6:595-598; Z Yan et al: Proc Natl Acad Sci USA 2000, 97:6716-6721) have exploited a unique feature of rAAV genomes, their ability to link together in doublets or strings, to bypass this size limitation. This technology could improve the chances for successful gene therapy of diseases like cystic fibrosis or Duchenne muscular dystrophy that lead to significant pulmonary morbidity
FAVOR (FAst Variability Optical Registration) -- A Two-telescope Complex for Detection and Investigation of Short Optical Transients
An astronomical complex intended to detect optical transients (OTs) in a wide
field and follow them up with high time resolution investigation is described.Comment: 4 pages, 3 figures. To be published in "Il Nuovo Cimento",
Proceedings of the 4th Rome Workshop on Gamma-Ray Bursts in the Afterglow
Era, eds. L. Piro, L. Amati, S. Covino, B. Gendr
ELM triggering conditions for the integrated modeling of H-mode plasmas
Recent advances in the integrated modeling of ELMy H-mode plasmas are
presented. A model for the H-mode pedestal and for the triggering of ELMs
predicts the height, width, and shape of the H-mode pedestal and the frequency
and width of ELMs. Formation of the pedestal and the L-H transition is the
direct result of ExB flow shear suppression of anomalous transport. The
periodic ELM crashes are triggered by either the ballooning or peeling MHD
instabilities. The BALOO, DCON, and ELITE ideal MHD stability codes are used to
derive a new parametric expression for the peeling-ballooning threshold. The
new dependence for the peeling-ballooning threshold is implemented in the ASTRA
transport code. Results of integrated modeling of DIII-D like discharges are
presented and compared with experimental observations. The results from the
ideal MHD stability codes are compared with results from the resistive MHD
stability code NIMROD.Comment: 12th International Congress on Plasma Physics, 25-29 October 2004,
Nice (France
The XMM-Newton serendipitous survey. VII. The third XMM-Newton serendipitous source catalogue
Thanks to the large collecting area (3 x ~1500 cm at 1.5 keV) and wide
field of view (30' across in full field mode) of the X-ray cameras on board the
European Space Agency X-ray observatory XMM-Newton, each individual pointing
can result in the detection of hundreds of X-ray sources, most of which are
newly discovered. Recently, many improvements in the XMM-Newton data reduction
algorithms have been made. These include enhanced source characterisation and
reduced spurious source detections, refined astrometric precision, greater net
sensitivity and the extraction of spectra and time series for fainter sources,
with better signal-to-noise. Further, almost 50\% more observations are in the
public domain compared to 2XMMi-DR3, allowing the XMM-Newton Survey Science
Centre (XMM-SSC) to produce a much larger and better quality X-ray source
catalogue. The XMM-SSC has developed a pipeline to reduce the XMM-Newton data
automatically and using improved calibration a new catalogue version has been
produced from XMM-Newton data made public by 2013 Dec. 31 (13 years of data).
Manual screening ensures the highest data quality. This catalogue is known as
3XMM. In the latest release, 3XMM-DR5, there are 565962 X-ray detections
comprising 396910 unique X-ray sources. For the 133000 brightest sources,
spectra and lightcurves are provided. For all detections, the positions on the
sky, a measure of the quality of the detection, and an evaluation of the X-ray
variability is provided, along with the fluxes and count rates in 7 X-ray
energy bands, the total 0.2-12 keV band counts, and four hardness ratios. To
identify the detections, a cross correlation with 228 catalogues is also
provided for each X-ray detection. 3XMM-DR5 is the largest X-ray source
catalogue ever produced. Thanks to the large array of data products, it is an
excellent resource in which to find new and extreme objects.Comment: 23 pages, version accepted for publication in A&
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