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Search Results: 1 - 10 of 537945 matches for " ?irkovi? Sa?a T. "
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Preliminary results of ion trajectory tracking in the acceleration region of the VINCY cyclotron
Ili? An?elija ?.,Risti?-?urovi? Jasna L.,irkoviSaa T.
Nuclear Technology and Radiation Protection , 2006, DOI: 10.2298/ntrp0601029i
Abstract: In an accelerating region of a cyclotron, an ion makes a large number of turns; thus, its n the Runge-Kutta method of the fourth order with the adaptive time step has been developed. The accuracy requirement is simultaneously set on position and momentum calculation. Magnetic fields used as inputs, have been evaluated in terms of the radial fluctuations of the orbital frequency, i.e. their isochronisms. Ion trajectory tracking has been performed for the following four test beams: H-, H+3, 4He+, He+, and 40Ar6+.
Preliminary results of the ion trajectory tracking in the acceleration region of the VINCY Cyclotron
Ili? An?elija ?.,Risti?-?urovi? Jasna L.,irkoviSaa T.
Journal of Automatic Control , 2006, DOI: 10.2298/jac0601005i
Abstract: In an accelerating region of a cyclotron an ion makes a large number of turns; thus its tracking requires fast as well as highly accurate computation. Computer code, based on the adaptive time step fourth order Runge Kutta method, has been developed. Accuracy requirement is set simultaneously on the position and momentum calculation. Magnetic fields used as input, have been evaluated in terms of the radial fluctuations of the orbital frequency, i.e. their isochronism. Ion trajectory tracking has been performed for the four test beams: H-, H2 +, 4He+, and 40Ar6+.
Automatic system for the mapping of the VINCY cyclotron magnetic field
Dobrosavljevi? Aleksandar,irkoviSaa T.,Ko?uti? ?or?e,Vukosavljevi? Ljubi?a
Nuclear Technology and Radiation Protection , 2006, DOI: 10.2298/ntrp0601013d
Abstract: The VINCY Cyclotron is the main part of the TESLA Accelerator Installation at the Vin a Institute of Nuclear Sciences in Belgrade. It is an isochroous cyclotron for the acceleration of both light and heavy ions. The pole of its magnet has the diameter of 2000 mm; its bending limit is 134 MeV, while its focusing limit is 73 MeV. This paper describes the magnetic field measurement system that has been used for the shimming of the VINCY Cyclotron magnet i.e., for precise shaping of its sectors and plugs. It is an automatic measurement system based on the Hall-probe that moves in the median plane between the poles of the magnet. We have used this system to obtain precise maps of the magnetic field for different operating regimes of the cyclotron needed in the process of shimming. The overall measurement uncertainty was estimated to be in the range of ±0.02%.
Focusing limit of a cyclotron: Axial betatron instability against beam dynamics approach
irkoviSaa T.,Risti?-?urovi? Jasna L.,Ili? An?elija,Ne?kovi? Neboj?a
Nuclear Technology and Radiation Protection , 2006, DOI: 10.2298/ntrp0602040c
Abstract: In an isochronous relativistic cyclotron, axial defocusing of a beam caused by the radial growth of the isochronous magnetic field is compensated by the azimuthal field gradient introduced by sectors. The focusing capabilities of sectors set the maximum ion energy obtainable from the machine. Usually, the focusing limit of a machine is determined by using the criterion for axial beam instability evolving from the equations of betatron oscillations. The obtained value of the focusing limit is approximate because the equations of betatron oscillations it originates from are approximate as well. The accurate value of the focusing limit is obtained by simulating accelerated beam dynamics in the extraction region. It is shown that the focusing limit of a cyclotron resulting from the two methods could differ for more than 9%. The suggested third method for focusing limit computation relies on the beam dynamics simulation along the critical equilibrium orbit rather than the acceleration orbit and thus it is less time consuming although equally accurate.
Beam stripping extraction from the VINCY cyclotron
Risti?-?urovi? Jasna L.,irkoviSaa T.,Ko?uti? ?or?e
Nuclear Technology and Radiation Protection , 2006, DOI: 10.2298/ntrp0601021r
Abstract: The extraction system of a cyclotron guides an ion beam from a spiral acceleration orbit, through an extraction trajectory, into a high energy transport line. The two methods commonly used to direct an ion into the extraction path are deflection, by the electric field of an electrostatic deflector, and ion stripping, by a thin carbon foil. Compared to the electrostatic deflector system, the stripping extraction provides a fast and easy change of the extracted ion energy and is easier to manufacture operate, and maintain. However, the extraction trajectory and dynamics of an ion beam after stripping are highly dependant on the ion energy and specific charge. Thus, when a multipurpose machine such as the VINCY Cyclotron is concerned, it is far from easy to deliver a variety of ion beams into the same high energy transport line and at the same time preserve a reasonable compactness of the extraction system. The front side stripping extraction system of the VINCY Cyclotron provides high (~70 MeV) and mid (~30 MeV) energy protons, as well as a number of heavy ions in broad energy ranges. The back side stripping extraction system extracts low energy protons (~18 MeV) and enables their simultaneous use with high energy protons at the front side of the machine.
Calibration of the simulation model of the VINCY cyclotron magnet
irkoviSaa,Risti?-?urovi? Jasna,Vorozhtsov Alexey S.,Vorozhtsov Serguei B.
Nuclear Technology and Radiation Protection , 2002, DOI: 10.2298/ntrp0202013c
Abstract: The MERMAID program will be used to isochronise the nominal magnetic field of the VINCY Cyclotron. This program simulates the response, i. e. calculates the magnetic field, of a previously defined model of a magnet. The accuracy of 3D field calculation depends on the density of the grid points in the simulation model grid. The size of the VINCY Cyclotron and the maximum number of grid points in the XY plane limited by MERMAID define the maximumobtainable accuracy of field calculations. Comparisons of the field simulated with maximum obtainable accuracy with the magnetic field measured in the first phase of the VINCY Cyclotron magnetic field measurements campaign has shown that the difference between these two fields is not as small as required. Further decrease of the difference between these fields is obtained by the simulation model calibration, i. e. by adjusting the current through the main coils in the simulation model.
Phenotypic diversity of Tunisian durum wheat landraces
A Sourour, K Chahine, T Youssef, SA Olfa, SA Hajer
African Crop Science Journal , 2010,
Abstract: Tunisia is considered as a diversification centre of durum wheat (Triticum durum Desf.) and barely (Hordeum vulgare). It is characterised by large genetic diversity; however, several genotypes are in the process of disappearance. The safeguard and rehabilitatation of this genetic inheritance requires genetic characterisation, evaluation and in-situ and ex-situ conservation. In this context, a local collection of thirty durum wheat accessions was evaluated using agronomical traits. Three other phenological traits: days to maturity, days to heading and filling period were evaluated. The phenotypic diversity was determined by the Shannon-Weaver diversity Index (H’) revealing that number of kernel/spike (H’=0.91), yield (H’=0.89), plant height (H’=0.87) and thousand kernel weight (H’=0.86) had the highest diversity index. Flag leaf area (H’=0.32) showed the weakest index. This germplasm presented average diversity (0.77) showing a large genetic variability. Correlations between traits showed a significant positive relation between yield and spikeless tillers/plant (0.90), thousand kernel weight (0.39), plant height (0.35) and flag leaf area (0.36), suggesting the usefulness of these parameter for selecting for improving grain yield. The components analysis explained 59.61% of total variability and led to identification of a group of accessions Jeneh kotifa 1, Jeneh kotifa 2, Jeneh kotifa 3, Sbei glabre, Hamira 1, Hamira 2, Biskri glabre, Mahmoudi, Biskri glabre AP2, Swabaa Elgia, Sbei, and Mahmoudi glabre showing the best agronomical characteristics. These genotypes can, therefore, be used as parents for the improvement of durum wheat.
Minihalo Model for the Low-Redshift Lyman alpha Absorbers Revisited
Lalovi?, A.,irkovi, M. M.
Serbian Astronomical Journal , 2008,
Abstract: We reconsider the basic properties of the classical minihalo model of Rees and Milgrom in light of the new work, both observational (on "dark galaxies" and masses of baryonic haloes) and theoretical (on the cosmological mass function and the history of star formation). In particular, we show that more detailed models of ionized gas in haloes of dark matter following isothermal and Navarro-Frenk-White density profile can effectively reproduce particular aspects of the observed column density distribution function in a heterogeneous sample of low-and intermediate-redshift Ly$alpha$ forest absorption lines.
Bilateral Supernumerary Kidneys: Incidental Finding in a Three-Month-Old Infant
A.Y Abdulkadir, A.T Sa’ad, A Ahidjo, A.A Ajape
African Journal of Urology , 2010,
Abstract: Supernumerary kidney (SNK) is a rare congenital anomaly with fewer than 100 cases reported in the English literature. The majority of these were unilateral and only five bilateral cases have been reported. We report an infant with six kidneys, incidentally diagnosed at ultrasonographic imaging after presenting with an anterior lower chest wall abscess. Confirmation of the diagnosis was confirmed by excretory urography. To our knowledge, this is the highest number of SNK reported.Key Words: Supernumerary kidneys, bilateral, anomaly, infant
Gut bacterial profile in patients newly diagnosed with treatment-na ve Crohn's disease
Ricanek P, Lothe SM, Frye SA, Rydning A, Vatn MH, T njum T
Clinical and Experimental Gastroenterology , 2012, DOI: http://dx.doi.org/10.2147/CEG.S33858
Abstract: t bacterial profile in patients newly diagnosed with treatment-na ve Crohn's disease Original Research (1479) Total Article Views Authors: Ricanek P, Lothe SM, Frye SA, Rydning A, Vatn MH, T njum T Published Date September 2012 Volume 2012:5 Pages 173 - 186 DOI: http://dx.doi.org/10.2147/CEG.S33858 Received: 14 May 2012 Accepted: 02 July 2012 Published: 24 September 2012 Petr Ricanek,1,2 Sheba M Lothe,1 Stephan A Frye,1 Andreas Rydning,2 Morten H Vatn,3,4 Tone T njum1,5 1Centre for Molecular Biology and Neuroscience and Department of Microbiology, Oslo University Hospital, Rikshospitalet, Oslo, 2Department of Gastroenterology, Akershus University Hospital, L renskog and Faculty Division Akershus University Hospital, University of Oslo, L renskog, 3EpiGen Institute, Faculty Division Akershus University Hospital, University of Oslo, L renskog, 4Department of Medicine, Oslo University Hospital, Rikshospitalet, Oslo, 5Centre for Molecular Biology and Neuroscience and Department of Microbiology, University of Oslo, Oslo, Norway Objectives: The aim of this study was to define the composition of the gut bacterial flora in Norwegian patients with early stage Crohn's disease (CD). Methods: By using a nonselective metagenomics approach, the general bacterial composition in mucosal biopsies from the ileum and the colon of five subjects, four patients with different phenotypes of CD, and one noninflammatory bowel disease control, was characterized. After partial 16S ribosomal RNA (rRNA) gene sequencing, BLAST homology searches for species identification and phylogenetic analysis were performed. Results: An overall biodiversity of 106 different bacterial operational taxonomic units (OTUs) was detected in the cloned libraries. Nearly all OTUs belonged to the phylae Bacteroidetes (42% in CD, 71% in the control) or Firmicutes (42% in CD, 28% in the control), except for some OTUs that belonged to the phylum Proteobacteria (15% in CD, 0% in the control) and a few OTUs that could not be assigned to a phylum (2% in CD, 1% in the control). Conclusion: Based on the high incidence of inflammatory bowel disease (IBD) in Norway, this pilot study represents a relevant determination of the gut microbiota in Norwegian patients compared to previous findings in other countries. The bacterial profile of Norwegian CD patients was found to be similar to that of CD patients in other countries. The findings do not support a particular bacterial composition as a predominant causative factor for the high incidence of IBD that exists in some countries.
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