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971.
Yamamoto H. Sugita K. Kanzaki N. Johja I. Hiraki Y. Kuwahara M. 《Aerospace and Electronic Systems Magazine, IEEE》1990,5(6):31-35
A method for enhancing the boundaries of magnetic resonance images (MRIs) using a V-filter (a spatial nonlinear filter) is presented. By iterated V-filtering the signal-to-noise ratio of the MRI can be increased while preserving edge sharpness. A simulation experiment was carried out to evaluate the filter, using clinical brain images. The boundaries of the brain tumor and edematous region were precisely extracted by the region segmentation techniques 相似文献
972.
J W Wilson J L Shinn R K Tripathi R C Singleterry M S Clowdsley S A Thibeault F M Cheatwood W Schimmerling F A Cucinotta G D Badhwar A K Noor M Y Kim F F Badavi J H Heinbockel J Miller C Zeitlin L Heilbronn 《Acta Astronautica》2001,49(3-10):289-312
The exposures in deep space are largely from the Galactic Cosmic Rays (GCR) for which there is as yet little biological experience. Mounting evidence indicates that conventional linear energy transfer (LET) defined protection quantities (quality factors) may not be appropriate for GCR ions. The available biological data indicates that aluminum alloy structures may generate inherently unhealthy internal spacecraft environments in the thickness range for space applications. Methods for optimization of spacecraft shielding and the associated role of materials selection are discussed. One material which may prove to be an important radiation protection material is hydrogenated carbon nanofibers. 相似文献
973.
R H Anken K Werner H Rahmann 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2002,30(4):849-853
Larval cichlid fish (Oreochromis mossambicus) siblings were subjected to 3 g hypergravity (hg) and total darkness for 21 days during development and subsequently processed for conventional histology. Further siblings reared at 1 g and alternating light/dark (12h:12h) conditions served as controls. Cell number counts of the visual Nucleus isthmi (Ni) versus the vestibular Nucleus magnocellularis (Nm) revealed that in experimental animals total cell number was decreased in the Ni, possibly due to retarded growth as a result of the lack of visual input whereas no effect was observed in the Nm. Calculating the percentual asymmetry in cell number (i.e., right vs. the left side of the brain), no effects of hg/darkness were seen in the Ni, whereas asymmetry was slightly increased in the Nm. Since the asymmetry of inner ear otoliths is decreased under hg, this finding may indicate efferent vestibular action of the CNS on the level of the Nm by means of a feedback mechanism. 相似文献
974.
Ts Dachev B Tomov Yu Matviichuk Pl Dimitrov J Lemaire Gh Gregoire M Cyamukungu H Schmitz K Fujitaka Y Uchihori H Kitamura G Reitz R Beaujean V Petrov V Shurshakov V Benghin F Spurny 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2002,30(4):917-925
The Mobile Radiation Exposure Control System's (Liulin-4 type) main purpose is to monitor simultaneously the doses and fluxes at 4 independent places. It can also be used for personnel dosimetry. The system consists of 4 battery-operated 256-channel dosimeters-spectrometers. We describe results obtained during the calibrations of the spectrometers at the Cyclotron facilities of the University of Louvain, Belgium and of the National Institute of Radiological Sciences-STA, Chiba, Japan with protons of energies up to 70 MeV. The angular sensitivities of the devices are studied and compared with Monte-Carlo predictions. We also present the results obtained at the HIMAC accelerator with 500 MeV/u Fe ions and at the CERN high energy radiation reference fields. Records made during airplane flights are shown and compared with the predictions of the CARI-6 model. 相似文献
975.
976.
977.
L W Townsend F A Cucinotta R Bagga R K Tripathi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,17(2):109-112
The fragmenting of high energy, heavy ions (HZE particles) by hydrogen targets is an important, physical process in several areas of space radiation research. In this work quantum mechanical optical model methods for estimating cross sections for HZE particle fragmentation by hydrogen targets are presented. The cross sections are calculated using a modified abrasion-ablation collision formalism adapted from a nucleus-nucleus collision model. Elemental and isotopic production cross sections are estimated and compared with report measurements for the breakup of neon, sulphur, and iron, nuclei at incident energies between 400 and 910 MeV/nucleon. Good agreement between theory and experiment is obtained. 相似文献
978.
H. Tanabe S. Isobe H. Akiyama Y. Koma T. Okabe J. Nishimura T. Maihara K. Mizutani J. Soegijo T.E. Hariadi S. Indrawan S. Slamet P. Anondo T. Tatang S. Agus W. Mulyana V.R. Suroto 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(1):69-72
A balloon observation of the total solar eclipse on 11 June 1983 was carried out as a cooperative work between Japanese and Indonesian teams. The observation was a photo-polarimetry of the F corona in both visual and near-infrared regions.The balloon of 15,000-m3 with a payload of 150-kg was launched at 7h13m on 11 June from Watukosek Balloon Base in East Java. Observation at an altitude of 30.5-km was successfully made during the totality (11h28~32m) at a position of ~40-km east-south-east from Jogjakarta.As a preliminary result, an excess in infrared brightness has been found near the position of 3.8R⊙ west from the sun, which may be due to thermal emission from a high-temperature dust cloud located around the sun. 相似文献
979.
R Facius K Scherer W Strauch L.V Nevzgodina E.N Maximova Yu.A Akatov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,18(12):195-204
Radiobiological effects of single cosmic heavy ions on individual, actively metabolizing test organisms, plants of Wolffia arrhiza, have been explored in an experiment flown aboard the Russian Biosatellite 10. Mortality induced during space flight, population dynamics during subsequent cultivation, and morphological anomalies occurring in the plants of these cultures were investigated. Correlation of these effects with the passage of a heavy ion was achieved by inserting monolayers of plants in a stack of surrounding plastic nuclear track detectors (BIO-STACK). Enhanced initial mortality and delayed decline of induced anomalies have been significantly associated with the passage of single heavy ions, in particular if ions penetrated the budding region of the plants. The prolonged persistence of anomalies in filial generations as an indication of delayed genetic damage has been detected for the first time as the consequence of the hit by a single heavy ion. Regarding radiation protection of space crew during prolonged missions, especially outside the magnetosphere, this appears to be a significant finding. 相似文献
980.
R.K. Gupta N.N. Murthy 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(6):385-394
The paper discusses the digital image processing system for NOAA/AVHRR data including Land applications — configured around VAX 11/750 host computer supported with FPS 100 Array Processor, Comtal graphic display and HP Plotting devices; wherein the system software for relational Data Base together with query and editing facilities, Man-Machine Interface using form, menu and prompt inputs including validation of user entries for data type and range; preprocessing software for data calibration, Sun-angle correction, Geometric Corrections for Earth curvature effect and Earth rotation offsets and Earth location of AVHRR image have been accomplished. The implemented image enhancement techniques such as grey level stretching, histogram equalization and convolution are discussed. The software implementation details for the computation of vegetative index and normalized vegetative index using NOAA/AVHRR channels 1 and 2 data together with output are presented; scientific background for such computations and obtainability of similar indices from Landsat/MSS data are also included. The paper concludes by specifying the further software developments planned and the progress envisaged in the field of vegetation index studies. 相似文献