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1

Cyclotron Production of Medical Radioisotopes  

NASA Astrophysics Data System (ADS)

The cyclotron production of radioisotopes for medical applications is gaining increased significance in diagnostic molecular imaging techniques such as PET and SPECT. In this regard, radioisotope production has never been easier or more convenient until de introduction of compact medical cyclotrons in the last few decades, which allowed the use of short-lived radioisotopes in in vivo nuclear medicine studies on a routine basis. This review outlines some general considerations about the production of radioisotopes using charged particle accelerators.

Ávila-Rodríguez, M. A.; Zárate-Morales, A.; Flores-Moreno, A.

2010-08-01

2

Cyclotron Production of Medical Radioisotopes  

SciTech Connect

The cyclotron production of radioisotopes for medical applications is gaining increased significance in diagnostic molecular imaging techniques such as PET and SPECT. In this regard, radioisotope production has never been easier or more convenient until de introduction of compact medical cyclotrons in the last few decades, which allowed the use of short-lived radioisotopes in in vivo nuclear medicine studies on a routine basis. This review outlines some general considerations about the production of radioisotopes using charged particle accelerators.

Avila-Rodriguez, M. A.; Zarate-Morales, A.; Flores-Moreno, A. [Unidad PET/CT-Ciclotron, Facultad de Medicina, Universidad Nacional Autonoma de Mexico, Edificio de Investigacion P.B, Cd. Universitaria, Circ. Interior, C.P. 04510 Mexico D.F. (Mexico)

2010-08-04

3

BEST medical radioisotope production cyclotrons  

NASA Astrophysics Data System (ADS)

Best Cyclotron Systems Inc (BCSI) is currently developing 14 MeV, 25 MeV, 35MeV and 70MeV cyclotrons for radioisotope production and research applications as well as the entire spectrum of targets and nuclear synthesis modules for the production of Positron Emission Tomography (PET), Single Photon Emission Computed Tomography (SPECT) and radiation therapy isotopes. The company is a subsidiary of Best Medical International, renowned in the field of medical instrumentation and radiation therapy. All cyclotrons have external negative hydrogen ion sources, four radial sectors with two dees in opposite valleys, cryogenic vacuum system and simultaneous beam extraction on opposite lines. The beam intensity ranges from 400 ?A to 1000 ?A, depending on the cyclotron energy and application [1].

Sabaiduc, Vasile; Milton, Bruce; Suthanthiran, Krishnan; Gelbart, W. Z.; Johnson, Richard R.

2013-04-01

4

BEST medical radioisotope production cyclotrons  

SciTech Connect

Best Cyclotron Systems Inc (BCSI) is currently developing 14 MeV, 25 MeV, 35MeV and 70MeV cyclotrons for radioisotope production and research applications as well as the entire spectrum of targets and nuclear synthesis modules for the production of Positron Emission Tomography (PET), Single Photon Emission Computed Tomography (SPECT) and radiation therapy isotopes. The company is a subsidiary of Best Medical International, renowned in the field of medical instrumentation and radiation therapy. All cyclotrons have external negative hydrogen ion sources, four radial sectors with two dees in opposite valleys, cryogenic vacuum system and simultaneous beam extraction on opposite lines. The beam intensity ranges from 400 {mu}A to 1000 {mu}A, depending on the cyclotron energy and application.

Sabaiduc, Vasile; Milton, Bruce; Suthanthiran, Krishnan; Johnson, Richard R. [Best Cyclotron Systems Inc., 7-8765 Ash Street, Vancouver, British Columbia, V6P 6T3 (Canada); Gelbart, W. Z. [Advanced System Designs Inc., 5295 Bear Bay Road, Garden Bay, BC, V0N 1S1 (Canada)

2013-04-19

5

[Evaluation of Radio-activated Compounds Produced in the Walls and Adjacent Areas of a Small Medical Cyclotron].  

PubMed

According to the (18)O(p, n) (18)F reaction, fast neutrons produced in the target will cause residual radioactivity in a cyclotron itself and in the concrete walls mainly after thermalization of neutrons.As exploratory work prior to decommissioning of a medical cyclotron facility, surface and core samples of the facility's concrete walls were collected after confirming the external radiation was at a low level based on hollow ionization chamber-type survey meter and glass dosimeter measurements. The residual radioactivity in these samples was measured by gamma-spectrometry. Residual radioactivity was detected in all of the components of the cyclotron. In the concrete, eight residual radioactive nuclides were identified. However, radioactivity concentrations of these radionuclides were less than that of (40)K which may exist generally in a natural environment. A clearance level for radioactive solid waste has not been defined nor implemented at present in Japan, and reliable evaluation will be required to minimize radioactive waste at the time of decommissioning. The present results provide basic data for establishment of regulatory guidelines for decommissioning of medical cyclotrons. PMID:21979783

Saito, Kyoko; Takahashi, Yasuyuki; Yamaguchi, Ichiro; Kimura, Ken-Ichi; Kanzaki, Takao; Shimada, Hirotaka; Otake, Hidenori; Oriuchi, Noboru; Endo, Keigo

2009-01-01

6

Development of a Medical Cyclotron Production Facility  

NASA Astrophysics Data System (ADS)

Development of a Cyclotron manufacturing facility begins with a business plan. Geographics, the size and activity of the medical community, the growth potential of the modality being served, and other business connections are all considered. This business used the customer base established by NuTech, Inc., an independent centralized nuclear pharmacy founded by Danny Allen. With two pharmacies in operation in Tyler and College Station and a customer base of 47 hospitals and clinics the existing delivery system and pharmacist staff is used for the cyclotron facility. We then added cyclotron products to contracts with these customers to guarantee a supply. We partnered with a company in the process of developing PET imaging centers. We then built an independent imaging center attached to the cyclotron facility to allow for the use of short-lived isotopes.

Allen, Danny R.

2003-08-01

7

Rotatable superconducting cyclotron adapted for medical use  

DOEpatents

A superconducting cyclotron (10) rotatable on a support structure (11) in an arc of about 180.degree. around a pivot axis (A--A) and particularly adapted for medical use is described. The rotatable support structure (13, 15) is balanced by being counterweighted (14) so as to allow rotation of the cyclotron and a beam (12), such as a subparticle (neutron) or atomic particle beam, from the cyclotron in the arc around a patient. Flexible hose (25) is moveably attached to the support structure for providing a liquified gas which is supercooled to near 0.degree. K. to an inlet means (122) to a chamber (105) around superconducting coils (101, 102). The liquid (34) level in the cyclotron is maintained approximately half full so that rotation of the support structure and cyclotron through the 180.degree. can be accomplished without spilling the liquid from the cyclotron. With the coils vertically oriented, each turn of the winding is approximately half immersed in liquid (34) and half exposed to cold gas and adequate cooling to maintain superconducting temperatures in the section of coil above the liquid level is provided by the combination of cold gas/vapor and by the conductive flow of heat along each turn of the winding from the half above the liquid to the half below.

Blosser, Henry G. (East Lansing, MI); Johnson, David A. (Williamston, MI); Riedel, Jack (East Lansing, MI); Burleigh, Richard J. (Berkeley, CA)

1985-01-01

8

Status of the Berkeley small cyclotron AMS project  

Microsoft Academic Search

A small, low-energy cyclotron (``cyclotrino'') has been designed and built at Berkeley for direct detection dating of 14C. The system combines the use of a negative ion source to reject 14N with the high resolution of a cyclotron to reject other background ions. In order to allow the dating of old and small samples, the present system incorporates a high-current

Kirk J. Bertsche; Peter G. Friedman; Donald E. Morris; Richard A. Muller; James J. Welch

1987-01-01

9

Status of the Berkeley small cyclotron AMS project  

NASA Astrophysics Data System (ADS)

A small, low-energy cyclotron ("cyclotrino") has been designed and built at Berkeley for direct detection dating of 14C. The system combines the use of a negative ion source to reject 14N with the high resolution of a cyclotron to reject other background ions. In order to allow the dating of old and small samples, the present system incorporates a high-current external ion source and injection beamline. The system is expected to be operational by mid-1988.

Bertsche, Kirk J.; Friedman, Peter G.; Morris, Donald E.; Muller, Richard A.; Welch, James J.

1987-11-01

10

Ion source and injection line for high intensity medical cyclotron.  

PubMed

A 14 MeV high intensity compact cyclotron, CYCIAE-14, was built at China Institute of Atomic Energy (CIAE). An injection system based on the external H- ion source was used on CYCIAE-14 so as to provide high intensity beam, while most positron emission tomography cyclotrons adopt internal ion source. A beam intensity of 100 ?A/14 MeV was extracted from the cyclotron with a small multi-cusp H- ion source (CIAE-CH-I type) and a short injection line, which the H- ion source of 3 mA/25 keV H- beam with emittance of 0.3??mm?mrad and the injection line of with only 1.2 m from the extraction of ion source to the medial plane of the cyclotron. To increase the extracted beam intensity of the cyclotron, a new ion source (CIAE-CH-II type) of 9.1 mA was used, with maximum of 500 ?A was achieved from the cyclotron. The design and test results of the ion source and injection line optimized for high intensity acceleration will be given in this paper. PMID:24593632

Jia, XianLu; Guan, Fengping; Yao, Hongjuan; Zhang, TianJue; Yang, Jianjun; Song, Guofang; Ge, Tao; Qin, Jiuchang

2014-02-01

11

Solid targets for 99mTc production on medical cyclotrons  

NASA Astrophysics Data System (ADS)

A method to produce solid 100Mo metal targets capable of withstanding proton irradiation with a power density of up to 1.1 kW/cm2 has been developed. The method of choice involves the electrodeposition of enriched 100Mo powder onto a tantalum backing, followed by high-temperature sintering in order to afford a coating that is sufficient to withstand bombardment for extended periods of time, yet reactive enough to allow for oxidative dissolution in seconds. This method is amenable to high-throughput techniques to allow for the production of 99mTc via the 100Mo(p,2n)99mTc reaction on small medical cyclotrons.

Hanemaayer, V.; Zeisler, S. K.; Buckley, K. R.; Klug, J.; Kovacs, M.; Bérnard, F.; Ruth, T. J.; Schaffer, P.

2012-12-01

12

Beam diagnostics for an 18 MeV medical cyclotron  

NASA Astrophysics Data System (ADS)

In this paper we investigate the profile of the 18 MeV proton beam from the IBA 18/9 cyclotron at the Hôpitaux Universitaires de Genève. The profile of the beam has a large impact on the isotope yields obtained from liquid or solid targets. The beam shape may be controlled by a beam-line, comprising beam focusing elements and diagnostic tools. To design the beam-line it is vital to have a good knowledge of the beam's transverse emittance as it exits the cyclotron. We have installed havar foils at various positions in the beam path, and analysed the irradiated foils by autoradiography. These measurements show that the beam shape varies considerably from one exit port to another, and have allowed us to estimate the beam's emittance, divergence, and the position of its focii.

Tamburella, C.; Giles, T. J.

2008-10-01

13

Cost benefit analysis of the radiological shielding of medical cyclotrons using a genetic algorithm  

NASA Astrophysics Data System (ADS)

Adequate radiation shielding is vital to the safe operation of modern commercial medical cyclotrons producing large yields of short-lived radioisotopes. The radiological shielding constitutes a significant capital investment for any new cyclotron-based radioisotope production facility; hence, the shielding design requires an accurate cost-benefit analysis often based on a complex multi-variant optimization technique. This paper demonstrates the application of a Genetic Algorithm (GA) for the optimum design of the high yield target cave of a Medical Cyclotron radioisotope production facility based in Sydney, Australia. The GA is a novel optimization technique that mimics the Darwinian Evolution paradigm and is ideally suited to search for global optima in a large multi-dimensional solution space.

Mukherjee, Bhaskar

2001-12-01

14

Medical Waste Management Implications for Small Medical Facilities.  

ERIC Educational Resources Information Center

Discusses the implications of the Medical Waste Management Act of 1988 for small medical facilities, public health, and the environment. Reviews health and environmental risks associated with medical waste, current regulatory approaches, and classifications. Concludes that the health risk of medical wastes has been overestimated; makes…

Byrns, George; Burke, Thomas

1992-01-01

15

A real-time intercepting beam-profile monitor for a medical cyclotron  

NASA Astrophysics Data System (ADS)

There is a lack of real-time continuous beam-diagnostic tools for medical cyclotrons due to high power deposition during proton irradiation. To overcome this limitation, we have developed a profile monitor that is capable of providing continuous feedback about beam shape and current in real time while it is inserted in the beam path. This enables users to optimize the beam profile and observe fluctuations in the beam over time with periodic insertion of the monitor.

Hendriks, C.; Uittenbosch, T.; Cameron, D.; Kellogg, S.; Gray, D.; Buckley, K.; Schaffer, P.; Verzilov, V.; Hoehr, C.

2013-11-01

16

High-Current Superconducting Cyclotron for Accelerator-Driven Subcritical Fission and for Medical Isotope Production  

NASA Astrophysics Data System (ADS)

A 50 MeV, 5mA proton cyclotron is being developed as the injector for a high-current driver for an accelerator-driven subcritical fission power system (ADSMS), and also for production of isotopes for medical physics. Two innovations have made it possible to design a cyclotron capable of >5 mA beam current: strong-focusing of the bunches by quadrupole focusing channels integrated on the pole faces of the sector magnets, and superconducting rf accelerating cavities to provide sufficient energy gain per turn to cleanly separate the orbits. Simulation results will be presented for the beam dynamics of the intense proton bunches during injection, acceleration, and extraction. Key features for both applications will be discussed.

Badgley, Karie; Assadi, Saeed; McIntyre, Peter; Sattarov, Akhdiyor

2011-10-01

17

Measurement of thermal neutron fluence distribution with use of 23Na radioactivation around a medical compact cyclotron.  

PubMed

A medical compact cyclotron produces about 10(15) neutrons per day along with 100 GBq of (18)F. Therefore, it is important to establish radiation safety guidelines on residual radioactivity for routine operation, maintenance work, and decommissioning. Thus, we developed a simple method for measuring the thermal neutrons in a cyclotron room. In order to verify the feasibility of our proposed method, we measured the thermal neutron distribution around a cyclotron by using the activation of (23)Na in salt. We installed 78 salt dosimeters in the cyclotron room with a 50 cm mesh. The photopeak of (24)Na was measured, and the neutron flux distribution was estimated. Monitoring the neutron flux distribution in a cyclotron room appears to be useful for not only obtaining an accurate estimate of the distribution of induced radioactivity, but also optimizing the shield design for radiation safety in preparation for the decommissioning process. PMID:20821115

Fujibuchi, Toshioh; Yamaguchi, Ichiro; Kasahara, Tetsuharu; Iimori, Takashi; Masuda, Yoshitada; Kimura, Ken-ichi; Watanabe, Hiroshi; Isobe, Tomonori; Sakae, Takeji

2009-07-01

18

Evaluation Study for the Production of the Medical Isotope ^90Y, using a Cyclotron  

NASA Astrophysics Data System (ADS)

The use of radioisotopes in therapy, medical imaging and laboratory tests is well-established worldwide. ^90Y is a very good therapeutic candidate for radioimmunotherapy applications. Traditionally, medical radioisotopes are produced using either nuclear reactors or proton accelerators. In this study, the medical isotope ^90Y has been produced using ^90Zr(n,p)^90Y nuclear reaction. Neutrons for the activation process were produced using ^natRh(p,xn) reaction with a 27 MeV proton beam from a cyclotron. Since ^90Y is a pure beta emitter, the gamma rays from the ^90Zr(n,2n)^89Zr reaction were used to quantify the incident neutron flux on the ^90Zr sample. Experimental results of the neutron production and ^90Y activity are presented.

Necsoiu, D.; Morgan, I. L.; Hupf, Homer; Armbruster, J.; Boyce, D.; El Bouanani, M.; McDaniel, F. D.

2000-10-01

19

Intake risk and dose evaluation methods for workers in radiochemistry labs of a medical cyclotron facility.  

PubMed

The aim of this paper is to evaluate the risks and doses for the internal contamination of the radiochemistry staff in a high workload medical cyclotron facility. The doses from internal contamination derive from the inhalation of radioactive gas leakage from the cells by personnel involved in the synthesis processes and are calculated from urine sample measurements. Various models are considered for the calculation of the effective committed dose from the analysis of these urine samples, and the results are compared with data obtained from local environmental measurement of the radioactivity released inside the lab. PMID:19741360

Calandrino, Riccardo; del Vecchio, Antonella; Savi, Annarita; Todde, Sergio; Belloli, Sara

2009-10-01

20

A CYCLOTRON CONCEPT TO SUPPORT ISOTOPE PRODUCTION FOR SCIENCE AND MEDICAL APPLICATIONS  

SciTech Connect

In August of 2009, the Nuclear Science Advisory Committee (NSAC) recommended a variable-energy, high-current multi-particle accelerator for the production of medical radioisotopes. The Oak Ridge National Laboratory is developing a technical concept for a 70 MeV dual-extraction multi-particle cyclotron that will meet the needs identified in the NSAC report. The cyclotron, which will be located at the Holifield Radioactive Ion Beam Facility (HRIBF), will operate on a 24/7 basis and will provide approximately 6000 hours per year of quality beam time for both the production R&D and production of medical and industrial radioisotopes. The proposed cyclotron will be capable of accelerating dual beams of 30 to 70 MeV H at up to 750 A, and up to 50 A of 15-35 MeV D , 35 MeV H2, and 70 MeV -particles. In dual-extraction H mode, a total of 750 A of 70 MeV protons will be provided simultaneously to both HRIBF and Isotope Production Facility. The isotope facility will consist of two target stations: a 2 water-cooled station and a 4 water-cooled high-energy-beam research station. The multi-particle capability and high beam power will enable research into new regimes of accelerator-produced radioisotopes, such as 225Ac, 211At, 68Ge, and 7B. The capabilities of the accelerator will enable the measurement of excitation functions, thick target yield measurements, research in high-power-target design, and will support fundamental research in nuclear and radiochemistry.

Egle, Brian [ORNL] [ORNL; Mirzadeh, Saed [ORNL] [ORNL; Tatum, B Alan [ORNL] [ORNL; Varma, Venugopal Koikal [Oak Ridge National Laboratory (ORNL)] [Oak Ridge National Laboratory (ORNL); Bradley, Eric Craig [ORNL] [ORNL; Burgess, Thomas W [ORNL] [ORNL; Aaron, W Scott [ORNL] [ORNL; Binder, Jeffrey L [ORNL] [ORNL; Beene, James R [ORNL] [ORNL; Saltmarsh, Michael John [ORNL] [ORNL

2013-01-01

21

Evaluating secondary neutron doses of a refined shielded design for a medical cyclotron using the TLD approach  

NASA Astrophysics Data System (ADS)

An increasing number of cyclotrons at medical centers in Taiwan have been installed to generate radiopharmaceutical products. An operating cyclotron generates immense amounts of secondary neutrons from reactions such the 18O(p, n)18F, used in the production of FDG. This intense radiation can be hazardous to public health, particularly to medical personnel. To increase the yield of 18F-FDG from 4200 GBq in 2005 to 48,600 GBq in 2011, Chung Shan Medical University Hospital (CSMUH) has prolonged irradiation time without changing the target or target current to meet requirements regarding the production 18F. The CSMUH has redesigned the CTI Radioisotope Delivery System shield. The lack of data for a possible secondary neutron doses has increased due to newly designed cyclotron rooms. This work aims to evaluate secondary neutron doses at a CTI cyclotron center using a thermoluminescent dosimeter (TLD-600). Two-dimensional neutron doses were mapped and indicated that neutron doses were high as neutrons leaked through self-shielded blocks and through the L-shaped concrete shield in vault rooms. These neutron doses varied markedly among locations close to the H218O target. The Monte Carlo simulation and minimum detectable dose are also discussed and demonstrated the reliability of using the TLD-600 approach. Findings can be adopted by medical centers to identify radioactive hot spots and develop radiation protection.

Lin, Jye-Bin; Tseng, Hsien-Chun; Liu, Wen-Shan; Lin, Ding-Bang; Hsieh, Teng-San; Chen, Chien-Yi

2013-11-01

22

Decommissioning procedures for an 11 MeV self-shielded medical cyclotron after 16 years of working time.  

PubMed

The present article describes the decommissioning of a compact, self-shielded, 11 MeV medical cyclotron. A Monte Carlo simulation of the possible nuclear reactions was performed in order to plan the decommissioning activities. In the course of the cyclotron dismantling, cyclotron components, shields, and floor concrete samples were measured. Residual activities were analyzed with a Ge(Li) detector and compared with simulation data. Doses to staff involved in the decommissioning procedure were monitored by individual TL dosimeters. The simulations identified five radioactive nuclides in shields and floor concrete: 55Fe and 45Ca (beta emitters, total specific activity: 2.29 x 10(4) Bq kg) and 152Eu, 154Eu, 60Co (gamma emitters, total specific activity: 1.62 x 10(3) Bq kg-1). Gamma-ray spectrometry confirmed the presence of gamma emitters, corresponding to a total specific activity of 3.40 x 10(2) Bq kg-1. The presence of the radioisotope 124Sb in the lead contained in the shield structure, corresponding to a simulated specific activity of 9.38 x 10(3) Bq kg-1, was experimentally confirmed. The measured dose from external exposure of the involved staff was <20 muSv, in accordance with the expected range of values between 10 and 20 muSv. The measured dose from intake was negligible. Finally, the decommissioning of the 11 MeV cyclotron does not represent a risk for the involved staff, but due to the presence of long-lived radioisotopes, the cyclotron components are to be treated as low level radioactive waste and stored in an authorized storage area. PMID:16691108

Calandrino, R; del Vecchio, A; Savi, A; Todde, S; Griffoni, V; Brambilla, S; Parisi, R; Simone, G; Fazio, F

2006-06-01

23

Cyclotrons: From Science to Human Health  

NASA Astrophysics Data System (ADS)

Lawrence's invention of the cyclotron, whose 80th anniversary we have just celebrated, not only revolutionized nuclear physics, but proved the starting point for a whole variety of recirculating accelerators, from the smallest microtron to the largest synchrotron, that have had an enormous impact in almost every branch of science and in several areas of medicine and industry. Cyclotrons themselves have proved remarkably adaptable, incorporating a variety of new ideas and technologies over the years: frequency modulation, edge focusing, AG focusing, separate magnet sectors, axial and azimuthal injection, ring geometries, stripping extraction, superconducting magnets and rf...... Even FFAGs, those most complex members of the cyclotron (fixed-magnetic-field) family, are making a comeback. Currently there are more than 50 medium or large cyclotrons around the world devoted to research. These provide intense primary beams of protons or stable ions, and correspondingly intense secondary beams of neutrons, pions, muons and radioactive ions, for experiments in nuclear, particle and condensed-matter physics, and in the materials and life sciences. Far outnumbering these, however, are the 800 or so small and medium cyclotrons used to produce radioisotopes for medical and other purposes. In addition, a rapidly growing number of 230-MeV proton cyclotrons are being built for cancer therapy - 12 brought into operation since 1998 and as many more in the works. Altogether, cyclotrons are flourishing!

Craddock, Michael

2011-04-01

24

Ion cyclotron range of frequencies heating of plasma with small impurity production  

DOEpatents

Plasma including plasma ions is magnetically confined by a magnetic field. The plasma has a defined outer surface and is intersected by resonance surfaces of respective common ion cyclotron frequency of a predetermined species of plasma ions moving in the magnetic field. A radio frequency source provides radio frequency power at a radio frequency corresponding to the ion cyclotron frequency of the predetermined species of plasma ions moving in the field at a respective said resonance surface. RF launchers coupled to the radio frequency source radiate radio frequency energy at the resonance frequency onto the respective resonance surface within the plasma from a plurality of locations located outside the plasma at such respective distances from the intersections of the respective resonance surface and the defined outer surface and at such relative phases that the resulting interference pattern provides substantially null net radio frequency energy over regions near and including substantial portions of the intersections relative to the radio frequency energy provided thereby at other portions of the respective resonance surface within the plasma.

Ohkawa, Tihiro (La Jolla, CA)

1987-01-01

25

Compact CC-18/9, CC-12, and MCC-30/15 cyclotrons for the production of medical radioisotopes  

NASA Astrophysics Data System (ADS)

A compact cyclotron concept is presented, the design features of advanced compact cyclotrons are highlighted, the performance specifications of the accelerators are described, and the results of numerical simulation and experimental investigation of the main (magnetic and acceleration) systems are given.

Bogdanov, P. V.; Vorogushin, M. F.; Lamzin, E. A.; Kukhtin, V. P.; Silaev, S. E.; Stogov, Yu. I.; Strokach, A. P.; Sytchevsky, S. E.; Shilkin, N. F.

2011-10-01

26

Measurements and evaluation of the risks due to external radiation exposures and to intake of activated elements for operational staff engaged in the maintenance of medical cyclotrons.  

PubMed

The aim of this paper is to assess the activation phenomena and to evaluate the risk of external exposure and intake doses for the maintenance staff of two medical cyclotrons. Two self-shielded cyclotrons are currently operating in the facility for the routine production of (11)C and (18)F. Four radiochemistry laboratories are linked to the cyclotrons by means of shielded radioisotope delivery lines. Radiopharmaceuticals are prepared both for the PET Diagnostic Department, where four CT-PET scanners are operating with a mean patient workload of 40 d(-1) and for [(18)F]FDG external distribution, to provide radiopharmaceuticals for other institutions. In spite of the fact that air contamination inside the radiochemistry laboratories during the synthesis represents the largest 'slice of the pie' in the evaluation of annual intake dose, potential contamination due to the activated particulate, generated during cyclotron irradiation by micro-corrosion of targets and other components potentially struck by the proton beam and generated neutrons, should be considered. In this regard, the most plausible long-lived (T(1/2) > 30 d) radioisotopes formed are: (97)Tc, (56)Co, (57)Co, (58)Co, (60)Co, (49)V, (55)Fe, (109)Cd, (65)Zn and (22)Na. The results for the operating personnel survey has revealed only low-level contamination for (65)Zn in one test, together with minor (18)F intake, probably due to the environmental dispersion of the radioisotope during the [(18)F]FDG synthesis. PMID:20028699

Calandrino, R; del Vecchio, A; Parisi, R; Todde, S; De Felice, P; Savi, A; Pepe, A; Mrskova, A

2010-06-01

27

An interactional approach to conceptualising small talk in medical interactions  

PubMed Central

In medical interactions, it may seem straightforward to identify ‘small talk’ as casual or social talk superfluous to the institutional work of dealing with patients’ medical concerns. Such a broad characterisation is, however, extremely difficult to apply to actual talk, and more specificity is necessary to pursue analyses of how small talk is produced and what it achieves for participants in medical interactions. We offer an approach to delineating a subgenre of small talk called topicalised small talk (TST), derived on the basis of conversation analytically-informed analyses of routine consultations involving orthopaedic surgeons and older patients. TST is a line of talk that is referentially independent from their institutional identities as patients or surgeons, oriented instead to an aspect of the personal biography of one (or both), or to some neutral topic available to interactants in any setting (e.g. weather). Importantly, TST is an achievement of both patient and surgeon in that generation and pursuit of topic is mutually accomplished. In an exploratory but systematic analysis, when this approach was applied to a purposive sample of surgeon-patient interactions, TST was much more prevalent in visits with White than African American patients. Accounts for possible ethnic differences in TST are suggested. PMID:21545445

Hudak, Pamela L.; Maynard, Douglas W.

2013-01-01

28

Analysis of induced radionuclides in replacement parts and liquid wastes in a medical cyclotron solely used for production of 18F for [18F]FDG.  

PubMed

Radioactivities produced in replacement parts and liquid wastes in a medical cyclotron used to produce (18)F for [(18)F]FDG with 10MeV protons were analyzed. Nineteen radionuclides were found in the replacement parts and liquid wastes. Among them, long-lived (56)Co in the Havar foils is critical in terms of radioactive waste management. The estimated dose level of exposure for the operating staff during the replacement of parts was around 310?Sv/y, which is smaller than the recommended dose limit for workers. PMID:23419430

Mochizuki, S; Ishigure, N; Ogata, Y; Kobayashi, T

2013-04-01

29

Simulating the impact of medical savings accounts on small business.  

PubMed Central

OBJECTIVE: To simulate whether allowing small businesses to offer employer-funded medical savings accounts (MSAs) would change the amount or type of insurance coverage. STUDY SETTING: Economic policy evaluation using a national probability sample of nonelderly non-institutionalized Americans from the 1993 Current Population Survey (CPS). STUDY DESIGN: We used a behavioral simulation model to predict the effect of MSAs on the insurance choices of employees of small businesses (and their families). The model predicts spending by each family in a FFS plan, an HMO plan, an MSA, and no insurance. These predictions allow us to compute community-rated premiums for each plan, but with firm-specific load fees. Within each firm, employees then evaluate each option, and the firm decides whether to offer insurance-and what type-based on these evaluations. If firms offer insurance, we consider two scenarios: (1) all workers elect coverage; and (2) workers can decline the coverage in return for a wage increase. PRINCIPAL FINDINGS: In the long run, under simulated conditions, tax-advantaged MSAs could attract 56 percent of all employees offered a plan by small businesses. However, the fraction of small-business employees offered insurance increases only from 41 percent to 43 percent when MSAs become an option. Many employees now signing up for a FFS plan would switch to MSAs if they were universally available. CONCLUSIONS: Our simulations suggest that MSAs will provide a limited impetus to businesses that do not currently cover insurance. However, MSAs could be desirable to workers in firms that already offer HMOs or standard FFS plans. As a result, expanding MSA availability could make it a major form of insurance for covered workers in small businesses. Overall welfare would increase slightly. PMID:10778824

Goldman, D P; Buchanan, J L; Keeler, E B

2000-01-01

30

New considerations for compact cyclotrons  

E-print Network

A compact cyclotron built with superconducting magnets could be a transformative solution to many scientific problems facing the defense, medical, and energy industries today. This thesis discusses three potential applications ...

Marshall, Eric S. (Eric Scott)

2012-01-01

31

Inexpensive rf modeling and analysis techniques as applied to cyclotrons  

NASA Astrophysics Data System (ADS)

A review and expansion of the circuit analogy method of modeling and analysing multiconductor TEM mode rf resonators is described. This method was used to predict the performance of the NSCL K500 and K1200 cyclotron resonators and the results compared well to the measured performance. The method is currently being applied as the initial stage of the design process to optimize the performance of the rf resonators for a proposed K250 cyclotron for medical applications. Although this technique requires an experienced rf modeller, the input files tend to be simple and small, the software is very inexpensive or free, and the computer runtimes are nearly instantaneous.

Vincent, John

2001-12-01

32

Small-size pulsed lasers in medical applications  

Microsoft Academic Search

The application of physics concepts to solve biological and medical problems are of growing interest. There are strong efforts to study the use of pulsed laser system in medical applications like dermatology, surgery, dental medicine and ophthalmology. Laser wavelengths cover a wide range from the ultraviolet to the far infrared. The most common radiation sources include all kind of lasers

M. Iberler; K. Frank

2002-01-01

33

A low background-rate detector for ions in the 5 to 50 keV energy range to be used for radioisotope dating with a small cyclotron  

SciTech Connect

Accelerator mass spectrometry in tandem Van de Graaff accelerators has proven successful for radioisotope dating small samples. We are developing a 20 cm diameter 30 to 40 keV cyclotron dedicated to high-sensitivity radioisotope dating, initially for /sup 14/C. At this energy, range and dE/dx methods of particle identification are impossible. Thus arises the difficult problem of reliably detecting 30 to 40 keV /sup 14/C at 10/sup -2/ counts/sec in the high background environment of the cyclotron, where lower energy ions, electrons, and photons bombard the detector at much higher rates. We have developed and tested an inexpensive, generally useful ion detector that allows dark-count rates below 10/sup -4/ counts/sec and excellent background suppression. With the cyclotron tuned near the /sup 13/CH background peak, to the frequency for /sup 14/C, the detector suppresses the background to 6 x 10/sup -4/ counts/sec. For each /sup 14/C ion the detectors grazing-incidence Al/sub 2/O/sub 3/ conversion dynode emits about 20 secondary electrons, which are independently multiplied in separate pores of a microchannel plate. The output signal is proportional to the number of secondary electrons, allowing pulse-height discrimination of background. We have successfully tested the detector with positive /sup 12/C, /sup 23/Na, /sup 39/K, /sup 41/K, /sup 85/Rb, /sup 87/Rb, and /sup 133/Cs at 5 to 40 keV, and with 36 keV negative /sup 12/C and /sup 13/CH. It should detect ions and neutrals of all species, at energies above 5 keV, with good efficiency and excellent background discrimination. Counting efficiency and background discrimination improve with higher ion energy. The detector can be operated at least up to 2 x 10/sup -7/ Torr and be repeatedly exposed to air. The maximum rate is 10/sup 6.4/ ions/sec in pulse counting mode and 10/sup 9.7/ ions/sec in current integrating mode.

Friedman, P.G.

1986-11-25

34

Factors Influencing Electronic Clinical Information Exchange in Small Medical Group Practices  

ERIC Educational Resources Information Center

Purpose: The purpose of this study was to identify the organizational factors that influence electronic health information exchange (HIE) by medical group practices in rural areas. Methods: A purposive sample of 8 small medical group practices in 3 experimental HIE regions were interviewed to determine the extent of clinical information exchange…

Kralewski, John E.; Zink, Therese; Boyle, Raymond

2012-01-01

35

Radiation surveillance in and around cyclotron facility.  

PubMed

The cyclotron is the most widely used particle accelerator for producing medically important radio nuclides. Many medical centers in India have installed compact medical cyclotrons for on-site production of short-lived positron-emitting radio nuclides such as (18)F, (13)N, and (11)C. A mandatory requirement for cyclotron installation is radiation control permit from Atomic Energy Regulatory Board. Cyclotron radiation survey is an integral part of the overall radiation safety in the cyclotron facility. Radiation surveillance in and around a newly installed cyclotron was performed using ionization chamber counter and Geiger Muller counter before, during and after operating the cyclotron. The readings were recorded at various locations where a high radiation field was expected. The results were recorded, tabulated and analyzed. The highest exposure level (0.93 ?Sv) was found at the back wall of the radiochemistry lab facing the cyclotron vault. Reason for the high exposure of 0.93 ?Sv/h: Synthesis of (18)F-Fluoro-Deoxy-Glucose ((18)F-FDG) was going in the synthesis module and activity ((18)F) was present in the synthesis module when reading was taken. All other values were found to be below the recommended levels of exposure. PMID:24019654

Kaur, Amandeep; Sharma, Sarika; Mittal, Br

2012-10-01

36

Theory of the Synchro-Cyclotron  

Microsoft Academic Search

In the synchro-cyclotron (or frequency-modulated cyclotron) the higher energies available are obtained at the expense of a decrease in the ion current compared with that available from the conventional cyclotron. This decrease results from the fact that during only a small fraction of the frequency-modulation cycle is it possible for ions to be captured into phase stable orbits that do

D. Bohm; L. L. Foldy

1947-01-01

37

Evaluation of Small-Group Teaching in Human Gross Anatomy in a Caribbean Medical School  

ERIC Educational Resources Information Center

Although there are a number of medical schools in the Caribbean islands, very few reports have come out so far in the literature regarding the efficacy of small-group teaching in them. The introduction of small-group teaching in the gross anatomy laboratory one and a half years ago at St. Matthew's University (SMU) on Grand Cayman appears to have…

Chan, Lap Ki; Ganguly, Pallab K.

2008-01-01

38

Cyclotron produced radiopharmaceuticals  

NASA Astrophysics Data System (ADS)

Some of the cyclotron-produced radionuclides may serve as important materials for the production of radiopharmaceuticals. This lecture deals with basic information relating to various aspects of these compounds. In comparison with radionuclides/compounds used for non-medical purposes, radiopharmaceuticals are subject to a broader scale of regulations, both from the safety and efficacy point of view; besides that, there are both radioactive and medical aspects that must be taken into account for any radiopharmaceutical. According to the regulations and in compliance with general rules of work with radioactivity, radiopharmaceuticals should only be prepared/manufactured under special conditions, using special areas and special equipment and applying special procedures (e.g. sterilisation, disinfection, aseptic work). Also, there are special procedures for cleaning and maintenance. Sometimes the requirements for the product safety clash with those for the safety of the personnel; several examples of solutions pertaining to these cases are given in the lecture. Also, the specific role of cyclotron radiopharmaceuticals is discussed.

Kopi?ka, K.; Fišer, M.; Hradilek, P.; Han?, P.; Lebeda, O.

2003-01-01

39

Medical Students Perceive Better Group Learning Processes when Large Classes Are Made to Seem Small  

PubMed Central

Objective Medical schools struggle with large classes, which might interfere with the effectiveness of learning within small groups due to students being unfamiliar to fellow students. The aim of this study was to assess the effects of making a large class seem small on the students' collaborative learning processes. Design A randomised controlled intervention study was undertaken to make a large class seem small, without the need to reduce the number of students enrolling in the medical programme. The class was divided into subsets: two small subsets (n?=?50) as the intervention groups; a control group (n?=?102) was mixed with the remaining students (the non-randomised group n?100) to create one large subset. Setting The undergraduate curriculum of the Maastricht Medical School, applying the Problem-Based Learning principles. In this learning context, students learn mainly in tutorial groups, composed randomly from a large class every 6–10 weeks. Intervention The formal group learning activities were organised within the subsets. Students from the intervention groups met frequently within the formal groups, in contrast to the students from the large subset who hardly enrolled with the same students in formal activities. Main Outcome Measures Three outcome measures assessed students' group learning processes over time: learning within formally organised small groups, learning with other students in the informal context and perceptions of the intervention. Results Formal group learning processes were perceived more positive in the intervention groups from the second study year on, with a mean increase of ??=?0.48. Informal group learning activities occurred almost exclusively within the subsets as defined by the intervention from the first week involved in the medical curriculum (E-I indexes>?0.69). Interviews tapped mainly positive effects and negligible negative side effects of the intervention. Conclusion Better group learning processes can be achieved in large medical schools by making large classes seem small. PMID:24736272

Hommes, Juliette; Arah, Onyebuchi A.; de Grave, Willem; Schuwirth, Lambert W. T.; Scherpbier, Albert J. J. A.; Bos, Gerard M. J.

2014-01-01

40

Selected List of Books and Journals for the Small Medical Library *  

PubMed Central

This updated list of 388 books and 140 journals is intended as a selection aid for the small library of a hospital, medical society, clinic, or similar organization. Books and journals are arranged by subject, with the books followed by an author index, and the journals by an alphabetical title listing. PMID:6041826

Brandon, Alfred N.

1967-01-01

41

Teaching ultrasound in developing countries: issues to consider when working in small medical facilities.  

PubMed

The author provides some suggestions for those considering travel to developing countries to provide training in ultrasound at small medical facilities. Issues discussed will include planning before the trip, personal safety and health while there, as well as equipment and travel issues. PMID:24901780

Brown, Douglas L

2014-03-01

42

Department of Engineering Spring 2011 B. Braun Medical: Non-Interchangeable Small-Bore Connectors for Liquids and  

E-print Network

PENNSTATE Department of Engineering Spring 2011 B. Braun Medical: Non-Interchangeable Small-Bore's objective was to develop four concepts of non-interchangeable small-bore connector pairs. Concept generation

Demirel, Melik C.

43

Development of a high current H(-) ion source for cyclotrons.  

PubMed

A multi-cusp DC H(-) ion source has been designed and fabricated for medical applications of cyclotrons. Optimization of the ion source is in progress, such as the improvement of the filament configuration, magnetic filter strength, extraction electrode's shape, configuration of electron suppression magnets, and plasma electrode material. A small quantity of Cs has been introduced into the ion source to enhance the negative ion beam current. The ion source produced 16 mA of DC H(-) ion beam with the Cs-seeded operation at a low arc discharge power of 2.8 kW. PMID:24593547

Etoh, H; Aoki, Y; Mitsubori, H; Arakawa, Y; Mitsumoto, T; Yajima, S; Sakuraba, J; Kato, T; Okumura, Y

2014-02-01

44

Factors associated with turnover interntion among nurses in small and medium-sized medical institutions  

Microsoft Academic Search

Objectives  The objective of this study was to evaluate factors associated with turnover intention among nurses in small and medium-sized\\u000a medical institutions.\\u000a \\u000a \\u000a \\u000a Methods  A self-administered questionaire survey was performed in 293 registered nurses, licensed practical nurses, and assistant nurses\\u000a working full-time in various medical institutions. Multiple linear regression analysis was conducted, with turnover intention\\u000a as the dependent variable, and nurses’ basic attributes

Yasushi Kudo; Toshihiko Satoh; Hisako Sinji; Takeo Miki; Mituyasu Watanabe; Koji Wada; Kaori Hosoi; Kasumi Hagita; Yukiko Saito; Yoshiharu Aizawa

2006-01-01

45

PET - radiopharmaceutical facilities at Washington University Medical School - an overview  

SciTech Connect

The PET program at Washington University has evolved over more than three decades of research and development in the use of positron-emitting isotopes in medicine and biology. In 1962 the installation of the first hospital cyclotron in the USA was accomplished. This first machine was an Allis Chalmers (AC) cyclotron and it was operated until July, 1990. Simultaneously with this cyclotron the authors also ran a Cyclotron Corporation (TCC) CS-15 cyclotron that was purchased in 1977. Both of these cyclotrons were maintained in-house and operated with a relatively small downtime (approximately 3.5%). After the dismantling of the AC machine in 1990, a Japanese Steel Works 16/8 (JSW-16/8) cyclotron was installed in the vault. Whereas the AC cyclotron could only accelerate deuterons (6.2 MeV), the JSW - 16/8 machine can accelerate both protons and deuterons, so all of the radiopharmaceuticals can be produced on either of the two presently owned accelerators. At the end of May 1993, the medical school installed the first clinical Tandem Cascade Accelerator (TCA) a collaboration with Science Research Laboratories (SRL) of Somerville, MA. Preliminary target testing, design and development are presently under way. In 1973, the University installed the first operational PETT device in the country, and at present there is a large basic science and clinical research program involving more than a hundred staff in nuclear medicine, radiation sciences, neurology, neurosurgery, psychiatry, cardiology, pulmonary medicine, oncology, and surgery.

Dence, C.S.; Welch, M.J. [Washington Univ., St. Louis, MO (United States)

1994-12-31

46

Cyclotrons as mass spectrometers  

SciTech Connect

The principles and design choices for cyclotrons as mass spectrometers are described. They are illustrated by examples of cyclotrons developed by various groups for this purpose. The use of present high energy cyclotrons for mass spectrometry is also described. 28 references, 12 figures.

Clark, D.J.

1984-04-01

47

Selected List of Books and Journals for the Small Medical Library *  

PubMed Central

This updated list of 389 books and 135 journals is intended as a selection aid for the small library of a hospital, medical society, clinic, or similar organization. Books and journals are arranged by subject, with the books followed by an author index, and the journals by an alphabetical title listing. Items suggested for first purchase by smaller libraries are noted by an asterisk. PMID:5582092

Brandon, Alfred N.

1971-01-01

48

Small group effectiveness in a Caribbean medical school's problem-based learning sessions  

PubMed Central

Purpose: The Tutorial Group Effectiveness Instrument was developed to provide objective information on the effectiveness of small groups. Student perception of small group effectiveness during the problem base learning (PBL) process has not been previously studied in Xavier University School of Medicine (Aruba, Kingdom of the Netherlands); hence, the present study was carried out. Methods: The study was conducted among second and third semester undergraduate medical students during the last week of September 2013, at Xavier University School of Medicine of the Netherlands. Students were informed about the objectives of the study and invited to participate after obtaining written, informed consent. Demographic information like gender, age, nationality, and whether the respondent had been exposed to PBL before joining the institution was noted. Student perception about small group effectiveness was studied by noting their degree of agreement with a set of 19 statements using a Likert-type scale. Results: Thirty-four of the 37 (91.9%) second and third semester medical students participated in the study. The mean cognitive score was 3.76 while the mean motivational and de-motivational scores were 3.65 and 2.51, respectively. The median cognitive category score was 27 (maximum score 35) while the motivation score was 26 (maximum score 35) and the de-motivational score was 12 (maximum score25). There was no significant difference in scores according to respondents’ demographic characteristics. Conclusion: Student perception about small group effectiveness was positive. Since most medical schools worldwide already have or are introducing PBL as a learning modality, the Tutorial Group Effectiveness Instrument can provide valuable information about small group functioning during PBL sessions. PMID:24699510

2014-01-01

49

Synchrotrons in cyclotron territory  

SciTech Connect

Synchrotrons and cyclotrons have an overlap in their particle and energy ranges. In proton radiotherapy, synchrotrons are proposed at 250 MeV, an energy usually served by cyclotrons. Heavy ion therapy has been synchrotron territory, but cyclotrons may be competitive. In nuclear science, heavy ion synchrotrons can be used in the cyclotron energy range of 10-200 MeV/u. Storage rings are planned to increase the flexibility of several cyclotrons. For atomic physics research, several storage rings are under construction for the energy range of 10 MeV/u and below.

Clark, D.J.; Gough, R.A.

1986-10-01

50

Selected list of books and journals for the small medical library.  

PubMed Central

This revised list of 492 books and 138 journals is intended as a selection guide for small or medium-sized hospital libraries or for the small medical library serving a specified clientele. It can also be used as a core list by small hospital library consortia. Books and journals are categorized by subject, with the books being followed by an author index and the journals by an alphabetical title listing. Items suggested for initial purchase by smaller libraries are indicated by an asterisk. To purchase the entire collection of books and to pay for annual subscriptions to all the journals would require an expenditure of about $22,500. The cost of only the asterisked items, recommended for first purchase, totals approximately $6,100. PMID:380695

Brandon, A N; Hill, D R

1979-01-01

51

Selected list of books and journals for the small medical library.  

PubMed Central

This revised list of 539 books and 136 journals is intended as a selection guide for small or medium-sized hospital libraries or for small medical libraries in comparable health care facilities. It can also be used as a core list by consortia of small hospital libraries. Books and journals are categorized by subject; the book list is followed by an author index and the list of journals by an alphabetical title listing. Items suggested for initial purchase by smaller libraries, 137 books and 54 journals, are indicated by asterisks. To purchase the entire collection of books and to pay for annual subscriptions to all the journals would require an expenditure of about $30,000. The cost of only the asterisked items, which are recommended for first purchase, totals approximately $8,900. PMID:7225656

Brandon, A N; Hill, D R

1981-01-01

52

Evaluation of small-group teaching in human gross anatomy in a Caribbean medical school  

NSDL National Science Digital Library

Although there are a number of medical schools in the Caribbean islands, very few reports have come out so far in the literature regarding the efficacy of small-group teaching. The introduction of small-group teaching in the gross anatomy laboratory one and a half years ago at St. Matthew's University (SMU) on Grand Cayman appears to have had a significant positive impact on the academic achievement of students in anatomy. This study surveyed the responses of the students to the small-group learning method in gross anatomy at SMU using a structured questionnaire. The results show that our students prefer this small-group learning method over a completely self-directed method in the gross anatomy lab because the study materials were carefully chosen and the study objectives were demonstrated by the resource person. However, teacher-centered teaching was deliberately avoided by fostering problem-solving skills in the anatomy lab sessions. Another aim of the small-group teaching at SMU was to develop the interpersonal and communication skills of the students, which are important in their later education and career.

Dr. Lap Ki Chan (The University of Hong Kong)

2008-01-01

53

Selected List of Books and Journals for the Small Medical Library *  

PubMed Central

This updated list of 410 books and 136 journals is intended as a selection aid for the small library of a hospital, medical society, clinic, or similar organization. Books and journals are arranged by subject, with the books followed by an author index, and the journals by an alphabetical title listing. Items suggested for first purchase by smaller libraries are noted by an asterisk. To purchase the entire collection of books and to pay for the annual subscription costs of all the journals would require an expenditure of about $12,000. To acquire only those items suggested for first purchase, approximately $3,250 would be needed. PMID:4702804

Brandon, Alfred N.

1973-01-01

54

Selected list of books and journals for the small medical library.  

PubMed Central

The impact that the hospital librarian's use of management techniques and comprehension of the highly competitive health care environment can have on collection development and resulting information services in his or her library is reviewed in the introduction to this revised list of 600 books and 139 journals. The list is intended as a selection guide for the small or medium-size library in a hospital or comparable medical facility, or a core collection for a consortium of small hospital libraries. Books and journals are categorized by subject; the book list is followed by an author/editor index and the subject list of journals by an alphabetical title listing. Items suggested for initial purchase by smaller libraries are indicated by asterisks. To purchase the entire collection of books and to pay for 1987 subscriptions to all journals would require about $52,600. The cost of only the asterisked items totals approximately $21,000. PMID:3594025

Brandon, A N; Hill, D R

1987-01-01

55

Selected list of Books and Journals for the small medical library.  

PubMed Central

The relationship of the "Selected List" to collection development is explored in the introduction to this revised list of 559 books and 135 journals. The list is intended as a selection guide for the small or medium-sized library in a hospital or comparable medical facility or as a core collection for a consortium of small hospital libraries. Books and journals are categorized by subject; the book list is followed by an author/editor index and the subject list of journals by an alphabetical title listing. Items suggested for initial purchase by smaller libraries (155 books and 54 journals) are indicated by asterisks. To purchase the entire collection of books and to pay for annual subscriptions would require an expenditure of about $38,900. The cost of only the asterisked items totals approximately $13,200. PMID:6190523

Brandon, A N; Hill, D R

1983-01-01

56

Basic steps in establishing effective small group teaching sessions in medical schools.  

PubMed

Small-group teaching and learning has achieved an admirable position in medical education and has become more popular as a means of encouraging the students in their studies and enhance the process of deep learning. The main characteristics of small group teaching are active involvement of the learners in entire learning cycle and well defined task orientation with achievable specific aims and objectives in a given time period. The essential components in the development of an ideal small group teaching and learning sessions are preliminary considerations at departmental and institutional level including educational strategies, group composition, physical environment, existing resources, diagnosis of the needs, formulation of the objectives and suitable teaching outline. Small group teaching increases the student interest, teamwork ability, retention of knowledge and skills, enhance transfer of concepts to innovative issues, and improve the self-directed learning. It develops self-motivation, investigating the issues, allows the student to test their thinking and higher-order activities. It also facilitates an adult style of learning, acceptance of personal responsibility for own progress. Moreover, it enhances student-faculty and peer-peer interaction, improves communication skills and provides opportunity to share the responsibility and clarify the points of bafflement. PMID:24353692

Meo, Sultan Ayoub

2013-07-01

57

Design and development of low-loss transformer for powering small implantable medical devices.  

PubMed

Small implantable medical devices, such as wireless capsule endoscopes, that can be swallowed have previously been developed. However, these devices cannot continuously operate for more than 8 h because of battery limitations; moreover, additional functionalities cannot be introduced. This paper proposes a design method for a high-efficiency energy transmission transformer (ETT) that can transmit energy transcutaneously to small implantable medical devices using electromagnetic induction. First, the authors propose an unconventional design method to develop such a high-efficiency ETT. This method can be readily used to calculate the exact transmission efficiency for changes in the material and design parameters (i.e., the magnetic material, transmission frequency, load resistance, etc.). Next, the ac-to-ac energy transmission efficiency is calculated and compared with experimental measurements. Then, suitable conditions for practical transmission are identified. A maximum efficiency of 33.1% can be obtained at a transmission frequency of 500 kHz and a receiving power of 100 mW for a receiving coil size of ¿5 mm × 20 mm. Future design optimization is possible by using this method. PMID:23853315

Shiba, K; Morimasa, A; Hirano, H

2010-04-01

58

Energy management techniques for ultra-small bio-medical implants  

E-print Network

Trends in the medical industry have created a growing demand for implantable medical devices. In particular, the need to provide medical professionals a means to continuously monitor bio-markers over long time scales with ...

Sanchez, William R

2012-01-01

59

Patterns of Relating Between Physicians and Medical Assistants in Small Family Medicine Offices  

PubMed Central

PURPOSE The clinician-colleague relationship is a cornerstone of relationship-centered care (RCC); in small family medicine offices, the clinician–medical assistant (MA) relationship is especially important. We sought to better understand the relationship between MA roles and the clinician-MA relationship within the RCC framework. METHODS We conducted an ethnographic study of 5 small family medicine offices (having <5 clinicians) in the Cincinnati Area Research and Improvement Group (CARInG) Network using interviews, surveys, and observations. We interviewed 19 MAs and supervisors and 11 clinicians (9 family physicians and 2 nurse practitioners) and observed 15 MAs in practice. Qualitative analysis used the editing style. RESULTS MAs’ roles in small family medicine offices were determined by MA career motivations and clinician-MA relationships. MA career motivations comprised interest in health care, easy training/workload, and customer service orientation. Clinician-MA relationships were influenced by how MAs and clinicians respond to their perceptions of MA clinical competence (illustrated predominantly by comparing MAs with nurses) and organizational structure. We propose a model, trust and verify, to describe the structure of the clinician-MA relationship. This model is informed by clinicians’ roles in hiring and managing MAs and the social familiarity of MAs and clinicians. Within the RCC framework, these findings can be seen as previously undefined constraints and freedoms in what is known as the Complex Responsive Process of Relating between clinicians and MAs. CONCLUSIONS Improved understanding of clinician-MA relationships will allow a better appreciation of how clinicians and MAs function in family medicine teams. Our findings may assist small offices undergoing practice transformation and guide future research to improve the education, training, and use of MAs in the family medicine setting. PMID:24615311

Elder, Nancy C.; Jacobson, C. Jeffrey; Bolon, Shannon K.; Fixler, Joseph; Pallerla, Harini; Busick, Christina; Gerrety, Erica; Kinney, Dee; Regan, Saundra; Pugnale, Michael

2014-01-01

60

Ernest Orlando Lawrence (1901-1958), Cyclotron and Medicine  

SciTech Connect

On August 8, 2001, Lawrence Berkeley National Laboratory celebrated the centennial of the birth of its founder (and namesake), Ernest Orlando Lawrence. For the occasion, many speeches were given and old speeches were remembered. We recall the words of the late Luis Alvarez, a Nobel Laureate and one of the Lawrence's closest colleagues: ''Lawrence will always be remembered as the inventor of the cyclotron, but more importantly, he should be remembered as the inventor of the modern way of doing science''. J. L. Heilbron and R. W. Seidel, in the introduction of their book, ''Lawrence and His Laboratory'' stated, ''The motives and mechanisms that shaped the growth of the Laboratory helped to force deep changes in the scientific estate and in the wider society. In the entrepreneurship of its founder, Ernest Orlando Lawrence, these motives, mechanisms, and changes came together in a tight focus. He mobilized great and small philanthropists, state and local governments, corporations, and plutocrats, volunteers and virtuosos. The work they supported, from astrophysics and atomic bombs, from radiochemistry to nuclear medicine, shaped the way we observe, control, and manipulate our environment.'' Indeed, all over the civilized world, the ways we do science changed forever after Lawrence built his famed Radiation Laboratory. In this editorial, we epitomize his legacy of changing the way we do medicine, thereby affecting the health and well being of all humanity. This year marks the 75th anniversary of the invention of the cyclotron by Ernest Orlando Lawrence at the University of California at Berkeley. Lawrence conceived the idea of the cyclotron early in 1929 after reading an article by Rolf Wideroe on high-energy accelerators. In the spring of 1930 one of his students, Nels Edlefsen, constructed two crude models of a cyclotron. Later in the fall of the same year, another student, M. Stanley Livingston, constructed a 13-cm diameter model that had all the features of early cyclotrons, accelerating protons to 80,000 volts using less than 1,000 volts on a semi-circular accelerating electrode, now called the ''dee''. Following the discovery by J. D. Cockcroft and E. T. S. Walton of how to produce larger currents at higher voltages, Lawrence constructed the first two-dee 27-Inch (69-cm) Cyclotron, which produced protons and deuterons of 4.8 MeV. The 27-Inch Cyclotron was used extensively in early investigations of nuclear reactions involving neutrons and artificial radioactivity. In 1939, working with William Brobeck, Lawrence constructed the 60-Inch (150-cm) Cyclotron, which accelerated deuterons to 19 MeV. It was housed in the Crocker Laboratory, where scientists first made transmutations of some elements, discovered several transuranic elements, and created hundreds of radioisotopes of known elements. At the Crocker Laboratory the new medical modality called nuclear medicine was born, which used radioisotopes for diagnosis and treatment of human diseases. In 1939 Lawrence was awarded the Nobel Prize in Physics, and later element 103 was named ''Lawrencium'' in his honor.

Chu, William T.

2005-09-01

61

Production of cyclotron radionuclides.  

National Technical Information Service (NTIS)

In the project, 4,450mCi of (sub 67)Ga, 2,097mCi of (sub 201)Ti, 2,626mCi of (sub 123)I and 1mCi of (sub 111)/In were supplied. For the efficient use of the cyclotron, the MC-50 cyclotron was opened to outside user and basic research project was carried o...

J. D. Lee, S. D. Yang, Y. S. Seo, K. S. Jeon, S. H. Ahn

1996-01-01

62

Production of cyclotron radionuclides.  

National Technical Information Service (NTIS)

In the project 3.732mCI of (sup 67)Ga, 2.216mCi of (sup 201)T1, 1.777mCi of (sup 123)I and 4mCi of (sup 111)In were supplied. For the efficient use of the cyclotron, the MC-50 Cyclotron was opened to outside user and basic research project was carried out...

J. D. Lee, S. M. Lim, S. D. Yang, Y. S. Suh, S. C. Kwon

1995-01-01

63

Small-scale medical waste incinerators - experiences and trials in South Africa  

SciTech Connect

Formal waste management services are not accessible for the majority of primary healthcare clinics on the African continent, and affordable and practicable technology solutions are required in the developing country context. In response, a protocol was established for the first quantitative and qualitative evaluation of relatively low cost small-scale incinerators for use at rural primary healthcare clinics. The protocol comprised the first phase of four, which defined the comprehensive trials of three incineration units. The trials showed that all of the units could be used to render medical waste non-infectious, and to destroy syringes or render needles unsuitable for reuse. Emission loads from the incinerators are higher than large-scale commercial incinerators, but a panel of experts considered the incinerators to be more acceptable compared to the other waste treatment and disposal options available in under-serviced rural areas. However, the incinerators must be used within a safe waste management programme that provides the necessary resources in the form of collection containers, maintenance support, acceptable energy sources, and understandable operational instructions for the incinerators, whilst minimising the exposure risks to emissions through the correct placement of the units in relation to the clinic and the surrounding communities. On-going training and awareness building are essential in order to ensure that the incinerators are correctly used as a sustainable waste treatment option.

Rogers, David E.C. [Environmental Process Solutions, Process Technology Centre, Council for Scientific and Industrial Research (CSIR), P.O. Box 395, Pretoria 0001 (South Africa)]. E-mail: drogers@csir.co.za; Brent, Alan C. [Life Cycle Engineering, Department of Engineering and Technology Management, University of Pretoria, Room 4-12, Engineering 2, Pretoria 0002 (South Africa)

2006-07-01

64

Selected list of books and journals for the small medical library.  

PubMed Central

The potential for the hospital library as an accepted patient-focused module is viewed in terms of both the present and the future--or no future--in the introduction to this revised recommended list of 606 books and 143 journals. Predecessors of this list have been intended as selection guides for a small or medium-size library in a hospital or comparable medical facility. Due to rapidly rising prices, the secondary purpose--a basic collection for a consortium of hospital libraries or a network sharing library resources--may eventually become its primary use. Books and journals are categorized by subject; the book list is followed by an author/editor index, and the subject list of journals by an alphabetical title listing. For the first time, a "minimal core collection" consisting of 85 books has been broken out from the 200 asterisked initial purchase books. To purchase the entire collection of books and to pay for the 1993 subscriptions would require about $87,000; the cost of only the asterisked books and journals totals $34,800. The "minimal core list" of books costs $11,600. PMID:8472001

Brandon, A N; Hill, D R

1993-01-01

65

Spatial cyclotron damping  

NASA Technical Reports Server (NTRS)

To examine spatial electron cyclotron damping in a uniform Vlasov plasma, it is noted that the plasma response to a steady-state transverse excitation consists of several terms (dielectric-pole, free-streaming, and branch-cut), but that the cyclotron-damped pole term is the dominant term for z l = c/w sub ce provided (w sub pe/w sub ce) squared (c/a) is much greater than 1. If the latter inequality does not hold, then the free-streaming and branch-cut terms persist well past z = c/w sub ce as w sub 1 approaches w sub ce, making experimental measurement of cyclotron damping essentially impossible. Considering only (w sub pe/w sub ce) squared (c/a) is much greater than 1, it is shown how collisional effects should be estimated and how a finite-width excitation usually has little effect on the cyclotron-damped part of the response. Criteria is established concerning collisional damping, measurable damping length sizes, and allowed uncertainty in the magnetic field Beta. Results of numerical calculations, showing the regions in the appropriate parameter spaces that meet these criteria, are presented. From these results, one can determine the feasibility of, or propose parameter values for, an experiment designed to measure spatial cyclotron damping. It is concluded that the electron temperature T sub e should be at least 1 ev., and preferably 10 ev. or higher, for a successful experiment.

Olson, C. L.

1970-01-01

66

A small portable proton exchange membrane fuel cell and hydrogen generator for medical applications.  

PubMed

Small, lightweight power sources for total artificial hearts (TAH), left ventricular assist devices (LVAD), and other medical products are under development. The new power source will provide 2 to 3 times the capacity of conventional batteries. The implications of this new power source are profound. For example, for the Heartmate LVAD, 5 to 8 hours of operation are obtained with 3 lb of lead acid batteries (Personal Communication Mr. Craig Sherman, Thermo Cardiosystems, Inc TCI 11/29/96). With the same weight, as much as 14 hours of operation appear achievable with the proton exchange membrane (PEM) fuel cell power source. Energy densities near 135 watt-hour/L are achievable. These values significantly exceed those of most conventional and advanced primary and secondary batteries. The improvement is mission dependent and even applies for the short deployment cited above. The comparison to batteries becomes even more favorable if the mission length is increased. The higher capacity requires only replacement of lightweight hydride cartridges and logistically available water. Therefore, when one spare 50 L hydride cartridge weighing 115 g is added to the reactant supply the energy density of the total system increases to 230 watt-hour/kg. This new power source is comprised of a hydrogen fueled, air-breathing PEM fuel cell and a miniature hydrogen generator (US Patent No 5,514,353). The fuel cell is of novel construction and differs from conventional bipolar PEM fuel cells by the arrangement of cells on a single sheet of ion-exchange membrane. The construction avoids the weight and volume penalty of conventional bipolar stacks. The hydrogen consumed by the fuel cell is generated load-responsively in the miniature hydrogen generator, by reacting calcium hydride with water, forming in the process hydrogen and lime. The generator is cartridge rechargeable and available in capacities providing up to several hundred watt-hours of electric power. PMID:9152494

Adlhart, O J; Rohonyi, P; Modroukas, D; Driller, J

1997-01-01

67

Cyclotron in 3D Model  

NSDL National Science Digital Library

This simulation illustrates the operation of a cyclotron, showing a charged particle moving through combined magnetic and electric fields. The particle, started near the center of the cyclotron, accelerates when passing through the gap between the electric electrodes and is turned by a perpendicular magnetic field. The geometry of the cyclotron, the magnitude of the electric and magnetic fields, and the properties of the charge are all adjustable. This page includes links to information on the operation of cyclotrons.

Hwang, Fu-Kwun; Wee, Loo K.

2010-12-10

68

Cyclotron Research and Applications  

NASA Astrophysics Data System (ADS)

The twenty years old cyclotron U-120M was upgraded for R&D and Production of Radiopharmaceuticals. R&D on short-lived Radiopharmaceuticals production is done at this accelerator. These Radiopharmaceuticals are eventually delivered to nearby hospitals. Development of new diagnostic radiopharmaceuticals is also pursued at the facility. your paper.

Mach, Rostislav

2010-01-01

69

Decay of References to Web sites in Articles Published in General Medical Journals: Mainstream vs Small Journals  

PubMed Central

Summary Background Over the last decade, Web sites (URLs) have been increasingly cited in scientific articles. However, the contents of the page of interest may change over the time. Objective To investigate the trend of citation to URLs in five general medical journals since January 2006 to June 2013 and to compare the trends in mainstream journals with small journals. Methods References of all original articles and review articles published between January 2006 and June 2013 in three regional journals – Archives of Iranian Medicine (AIM), Eastern Mediterranean Health Journal (EMHJ), and Journal of Postgraduate Medical Institute (JPMI) – and two mainstream journals – The Lancet and British Medical Journal (BMJ) – were reviewed. The references were checked to determine the frequency of citation to URLs as well as the rate of accessibility of the URLs cited. Results A total of 2822 articles was studied. Since January 2006 onward, the number of citations to URLs increased in the journals (doubling time ranged from 4.2 years in EMHJ to 13.9 years in AIM). Overall, the percentage of articles citing at least one URL has increased from 24% in 2006 to 48.5% in 2013. Accessibility to URLs decayed as the references got old (half life ranged from 2.2 years in EMHJ to 5.3 years in BMJ). The ratio of citation to URLs in the studied mainstream journals, as well as the ratio of URLs accessible were significantly (p<0.001) higher than the small medical journals. Conclusion URLs are increasingly cited, but their contents decay with time. The trend of citing and decaying URLs are different in mainstream journals compared to small medical journals. Decay of URL contents would jeopardize the accuracy of the references and thus, the body of evidence. One way to tackle this important obstacle is to archive URLs permanently. PMID:24454575

Habibzadeh, P.

2013-01-01

70

In Comparative Analysis for Fuel Burnup of Fuel Assembly Designs for the 300 kW Small Medical Reactor  

NASA Astrophysics Data System (ADS)

A 300 kW small medical reactor was designed to be used for boron neutron capture therapy (BNCT) at KAIST in 1996 [1]. In this paper, analysis for the core life cycle of the original design of the BNCT facility and modifications of the fuel assembly configuration and enrichment to get a proper life cycle were performed and a criticality, neutron flux distribution and fuel burnup calculations were carried out.

Sambuu, Odmaa; Nanzad, Norov

2009-03-01

71

A 40 keV cyclotron for radioisotope dating  

Microsoft Academic Search

We have built and begun testing a small low energy negative ion cyclotron for direct detection of 14C. At present, the cyclotron is operated in a high resolution mode at the 31st harmonic, with 1-2 kV on the dees. The high harmonic and a minimum number of turns of approximately 100, should give a fwhm mass resolution of about 1\\/30000

James J. Welch; Kirk J. Bertsche; Peter G. Friedman; Donald E. Morris; Richard A. Muller; Pieter P. Tans

1984-01-01

72

Low-cost and small-sized medical microwave radiometer design  

Microsoft Academic Search

In the past decades research in microwave radiometry has been conducted for use in medical applications. Detection of breast cancer, hyperthermia, and measurment the temperature brain temperature of newborn babies are areas here this technique have been used. Russian scientists have developed a radiometer which is sold under the name of RTM-01 for the detection of breast cancer. The technical

O. Klemetsen; Y. Birkelund; S. Jacobsen

2010-01-01

73

The Role of International Medical Graduates in America?s Small Rural Critical Access Hospitals  

ERIC Educational Resources Information Center

Critical access hospitals (CAHs) are a federal Medicare category for isolated rural facilities with 15 or fewer acute care beds that receive cost-based reimbursement from Medicare. Purpose: This study examines the role of foreign-born international medical graduates (IMGs) in the staffing of CAHs. Methods: Chief executive officers (CEOs) of CAH…

Hagopian, Amy; Thompson, Matthew J.; Kaltenbach, Emily; Hart, L. Gary

2004-01-01

74

Radioactive nuclei for medical applications  

NASA Astrophysics Data System (ADS)

The radioisotopes used for labeling the diagnostic and therapeutic radiopharmaceuticals are contemporaneously produced using neutrons in reactors and light charged particles from accelerators (cyclotrons). After the presentation of both methods the commercially available cyclotrons are reviewed. Some examples of the most popular medical radioisotopes are given. The new Radiopharmaceuticals Production and Research Centre at the University of Warsaw is presented.

Jastrz?bski, Jerzy

2011-01-01

75

Central region of SKKUCY-9 compact cyclotron  

NASA Astrophysics Data System (ADS)

The development of a 9 MeV compact cyclotron for the production of radioisotopes for medical applications has been recently completed. The machine accelerates negative hydrogen ions generated from an internal PIG (Penning Ion Gauge) ion source following spiral orbits. Some of the structures designed for early beam acceleration, including a pair of center poles providing ions a circular direction, the head of the ion source, and the electrodes, are located in the center of the cyclotron. In this paper we discuss and evaluate the design of the central region that pulls the ions from the chimney of the ion source and directs them into the equilibrium orbit. The magnetic field produced by the center poles was analyzed using the magnetic solver in OPERA-3D TOSCA, and the phase error and ion equilibrium orbit, which is dependent on the kinetic energy within the designed field, were calculated using CYCLONE v8.4. The electric field produced in the acceleration gap was designed using an electrostatic solver. Then, the single beam trajectory was calculated by our own Cyclotron Beam Dynamics (CBD) code. The early orbits, vertical oscillation, acceptable RF phase and the energy gain during the early turns was evaluated. Final goal was to design the central region by the iterative optimization process and verify it with 1 MeV beam experiment.

Jung, S. Y.; Kim, H. W.; Ghergherehchi, M.; Park, J. K.; Chai, J. S.; Kim, S. H.

2014-04-01

76

Aiming for Prevention: Medical and Public Health Approaches to Small Arms, Gun Violence, and Injury  

Microsoft Academic Search

The level of global small arms violence is enormous and the scale of human suffering it causes is immense, although poorly counted. It causes at least hundreds of thousands of deaths and more than a million injuries each year, as well as permanent physical and psychological damage, destruction of families, lost productivity, and diversion of resources from basic health services.

Brian Rawson

77

The effect of acute medication with cilostazol, an anti-platelet drug, on the outcome of small vessel brain infarction.  

PubMed

Our objective was to investigate the effect of cilostazol in acute therapy for small vessel stroke patients. The neurologic deficits in some patients of small vessel brain infarction will progress even if a patient takes immediate medical treatments including aspirin or other antiplatelet drugs. In Japan, cilostazol, presenting not only the antiplatelet effect but also the arteriole dilation, is used for treatment of ischemic stroke. In this study, acute stroke patients with small vessel occlusion were treated with cilostazol instead of aspirin in the conventional medication after 2010. Therefore, patients between April 2007 and March 2009 were classified into the conventional group (group-con, n=220), and patients between April 2010 and March 2012 were classified into the cilostazol group (group-cilo, n=230). Enrolled patients were classified into lacunar infarction (LI) and branch atheromatous disease. Progressing stroke was defined as the increase of National Institutes of Health Stroke Scale score of 2 or more within 48 hours. The clinical outcome was assessed by the modified Rankin Scale (mRS) score at 1 month. As the result, the significant reduction in progressing stroke was dominant in the LI of brainstem (P=.01). The length of hospital stay was significantly shorter in the group-cilo compared with the group-con (18.6 and 21.2 days, P=.03). Moreover, mRS score at 1 month was significantly lower in the group-cilo than the group-con (1.9 and 2.3, P=.03). In conclusion, cilostazol reduced the risk of early neurologic deterioration of patients with small vessel brain infarction. It is eagerly desired to conduct a large randomized control trial. PMID:24513481

Nakase, Taizen; Sasaki, Masahiro; Suzuki, Akifumi

2014-07-01

78

MC-50 AVF cyclotron operation.  

National Technical Information Service (NTIS)

The first cyclotron in Korea, MC-50 cyclotron is used for neutron irradiations, radionuclides developments and productions, and material and biomedical researches. 50.5 MeV and 35 MeV proton beams have been extracted with 20 - 70 (mu)A. Total beam extract...

J. S. Chae, D. H. Lee, Y. S. Kim, C. W. Park, Y. M. Lee

1995-01-01

79

Structural capabilities in small and medium-sized patient-centered medical homes.  

PubMed

Objectives 1) Evaluate structural capabilities associated with the patient-centered medical home (PCMH) model in PCMH pilots in Colorado, Ohio, and Rhode Island; 2) evaluate changes in capabilities over 2 years in the Rhode Island pilot; and 3) evaluate facilitators and barriers to the adoption of capabilities. Study Design We assessed structural capabilities in the 30 pilot practices using a cross-sectional study design and examined changes over 2 years in 5 Rhode Island practices using a pre/post design. Methods We used National Committee for Quality Assurance's Physician Practice Connections-Patient-Centered Medical Home (PPC/PCMH) accreditation survey data to measure capabilities. We stratified by high and low performance based on total score and by practice size. We analyzed change from baseline to 24 months for the Rhode Island practices. We analyzed qualitative data from interviews with practice leaders to identify facilitators and barriers to building capabilities. Results On average, practices scored 73 points (out of 100 points) for structural capabilities. High and low performers differed most on electronic prescribing, patient self-management, and care-management standards. Rhode Island practices averaged 42 points at baseline, and reached 90 points by the end of year 2. Some of the key facilitators that emerged were payment incentives, "transformation coaches," learning collaboratives, and data availability supporting performance management and quality improvement. Barriers to improvement included the extent of transformation required, technology shortcomings, slow cultural change, change fatigue, and lack of broader payment reform. Conclusions For these early adopters, prevalence of structural capabilities was high, and performance was substantially improved for practices with initially lower capabilities. We conclude that building capabilities requires payment reform, attention to implementation, and cultural change. PMID:25295546

Alidina, Shehnaz; Schneider, Eric C; Singer, Sara J; Rosenthal, Meredith B

2014-01-01

80

A novel superconducting cyclotron for therapy and radioisotope production  

NASA Astrophysics Data System (ADS)

The design of a four sector compact superconducting cyclotron, able to accelerate up to 250 A MeV light ions with charge/mass ratio 0.5, is in progress. Light ions like 12C 6+, 10B 5+, 6Li 3+ will be extracted by electrostatic deflectors while H 2+ ions can be extracted also by stripping, therefore a beam power of 10 kW or more is available. This cyclotron can be used for radiotherapy with protons or carbon ions and also to drive a facility for production of unusual medical radioisotopes. The main parameters and some features of the machine are here presented.

Calabretta, Luciano; Cuttone, Giacomo; Maggiore, Mario; Re, Maurizio; Rifuggiato, Danilo

2006-06-01

81

Small group learning in medical education: a second look at the Springer, Stanne, and Donovan meta-analysis.  

PubMed

All in all, the evidence is not convincing. Only four of the nine randomized studies used the conventional small-group learning paradigm and qualify as studies of small-group learning, which are relevant to medical education. The results of one of the four are impossible to interpret because of the involvement of the investigator in teaching and test construction. The three remaining studies showed no effect, a negative effect, and a positive effect, respectively. The nonrandomized studies failed to establish the comparability of the groups. The evidence does not support the authors' call for "more widespread implementation of small-group learning in undergraduate SMET". Small-group learning has not been shown to support the acquisition of content any better [or worse] than large-group learning. In medical education, small-groups are employed in large part to develop team work skills, communication skills, and peer- and self-assessment skills. But these outcomes are not addressed in this meta-analysis. More seriously, our rereading of these studies raises general concerns about meta-analysis in education, which have important implications for evidence-based medical education. The meta-analysis under discussion at first appeared to be just the kind needed to guide an evidence-based educational enterprise. However, a closer look revealed both what is lacking in the meta-analysis and some of the ways educational research and reporting need to be changed if anything like evidence-based education is ever to become a reality. At the least, study design must be clearly described. In addition, if the design is nonrandomized, the groups should be described in sufficient detail to allow a meaningful interpretation of the role of preexisting differences on the outcome measures. (This is why we limited our discussion here to the randomized studies.) Also, effect-size measures should be reported for all comparisons that bear on the impact of the intervention, including preexisting differences. Reporting significance is not enough. This shows only whether sampling error can be ruled out (with a low probability of error, p < .05) as a possible explanation of the connection between the intervention and the outcome. The effect can still be trivial and the comparisons confounded. In addition, descriptions of the actual educational interventions employed need to be more comprehensive and precise. For the most part, the papers would have been strengthened by providing more information for replicating the studies and for deciding which should be included in a given meta-analysis. Perhaps most seriously, our rereading of these studies makes us wonder about the possibility of meaningfully synthesizing the results of educational studies, given their idiosyncrasies and their many extraneous, uncontrolled factors. The conclusions from most educational studies, then--whether randomized or not--must be highly qualified, with explicit warnings about preexisting differences and other confounding factors that plausibly account for the study results. However, these narrative qualifications do nothing to adjust the effect-size measures, which are typically pooled or synthesized across studies--confounds and all. The idiosyncrasies of the studies seem to preclude a blanket qualification that can be applied conceptually across the collection of studies to arrive at a sound conclusion from the synthesis. In brief, the meta-analysis considered here does not support the application of small-group learning in medical education and it raises questions about meta-analysis in education with implications for evidence-based education. PMID:12632701

Colliver, Jerry A; Feltovich, Paul J; Verhulst, Steven J

2003-01-01

82

Ion cyclotron resonance cell  

DOEpatents

An ion cyclotron resonance cell is disclosed having two adjacent sections separated by a center trapping plate. The first section is defined by the center trapping plate, a first end trapping plate, and excitation and detector electrodes. The second section includes a second end trapping plate spaced apart from the center plate, a mirror, and an analyzer. The analyzer includes a wavelength-selective light detector, such as a detector incorporating an acousto-optical device (AOD) and a photodetector. One or more ion guides, grounded plates with holes for the ion beam, are positioned within the vacuum chamber of the mass spectrometer between the ion source and the cell. After ions are trapped and analyzed by ion cyclotron resonance techniques in the first section, the ions of interest are selected according to their mass and passed into the second section for optical spectroscopic studies. The trapped ions are excited by light from a laser and caused thereby to fluoresce. The fluorescent light emitted by the excited ions is reflected by the mirror and directed onto the detector. The AOD is scanned, and the photodetector output is recorded and analyzed. The ions remain in the second section for an extended period, enabling multiple studies to be carried out on the same ensemble of ions. 5 figs.

Weller, R.R.

1995-02-14

83

Ion cyclotron resonance cell  

DOEpatents

An ion cyclotron resonance cell having two adjacent sections separated by a center trapping plate. The first section is defined by the center trapping plate, a first end trapping plate, and excitation and detector electrodes. The second section includes a second end trapping plate spaced apart from the center plate, a mirror, and an analyzer. The analyzer includes a wavelength-selective light detector, such as a detector incorporating an acousto-optical device (AOD) and a photodetector. One or more ion guides, grounded plates with holes for the ion beam, are positioned within the vacuum chamber of the mass spectrometer between the ion source and the cell. After ions are trapped and analyzed by ion cyclotron resonance techniques in the first section, the ions of interest are selected according to their mass and passed into the second section for optical spectroscopic studies. The trapped ions are excited by light from a laser and caused thereby to fluoresce. The fluorescent light emitted by the excited ions is reflected by the mirror and directed onto the detector. The AOD is scanned, and the photodetector output is recorded and analyzed. The ions remain in the second section for an extended period, enabling multiple studies to be carried out on the same ensemble of ions.

Weller, Robert R. (Aiken, SC)

1995-01-01

84

A 40 keV cyclotron for radioisotope dating  

NASA Astrophysics Data System (ADS)

We have built and begun testing a small low energy negative ion cyclotron for direct detection of 14C. At present, the cyclotron is operated in a high resolution mode at the 31st harmonic, with 1-2 kV on the dees. The high harmonic and a minimum number of turns of approximately 100, should give a fwhm mass resolution of about {1}/{30000} — sufficient to suppress the background from molecular ions such as 13CH -. Background such as scattered ions of 12C - and 13C - should be totally suppressed by the cyclotron acceleration process. (At the 88? cyclotron at LBL we found that ions only 1% off-resonance are suppressed by more than a factor of 10 17.) A miniature Cs sputter source located at the center of the cyclotron is expected to provide more than 1 ?A of negative carbon ions. Negative ions are used in order to eliminate the interference from 14N. Unlike high energy cyclotrons, focussing is obtained solely from the axial components of the accelerating electric field. The magnetic field is kept flat to within 1 part in 10 4 in order to maintain exact isochronism throughout the several thousand accelerating rf cycles. The low final energy of 40 keV eliminates any danger from radiation or need for shielding, and the final orbit radius of only 10.5 cm, reduce the size and cost of the machine to that of conventional mass spectrometers.

Welch, James J.; Bertsche, Kirk J.; Friedman, Peter G.; Morris, Donald E.; Muller, Richard A.; Tans, Pieter P.

1984-11-01

85

3D Observations of Electromagnetic Ion Cyclotron Wave Propagation in a Laboratory Plasma Column  

E-print Network

3D Observations of Electromagnetic Ion Cyclotron Wave Propagation in a Laboratory Plasma Column in the IEEE Transactions on Plasma Science Special Issue: Images in Plasma Science, 27 (1), 1999 Abstract The propagation of Electromagnetic Ion Cyclotron Waves (EMICW's) as launched by an antenna of small transverse

California at Los Angles, University of

86

Design of Small-sized and Low-cost Front End to Medical Microwave Radiometer  

PubMed Central

We have investigated the possibility of building a Dicke radiometer that is inexpensive, small-sized, stable, high sensitivity and consists of readily available microwave components. The selected frequency band is at 3–4 GHz and can be used for breast cancer detection, with sufficient spatial resolution. We have found microwave components that are small (< 5mm × 5 mm) and provide sufficient sensitivity. We have built two different Dicke radiometers: One is of conventional design with Dicke switch at front end to select antenna or noise rererence and the other with a low noise amplifier before the Dicke Switch. We have tested this concept with simulations and built prototypes. The two designs provide a gain of approximately 50 dB, and bandwidth of about 500 MHz. One of the designs has a stability ? > 1 and the other design provide instability ? < 1 for a part of the pass band. The prototypes are tested for sensitivity after calibration in two different known temperature waterbaths. The results show that the design with the low noise amplifier before the Dicke switch has 36% higher sensitivity than the other design with Dicke switch in front.

Klemetsen, O.; Birkelund, Y.; Maccarini, P. F.; Stauffer, P.; Jacobsen, S. K.

2013-01-01

87

Achieving Small Structures in Thin NiTi Sheets for Medical Applications with Water Jet and Micro Machining: A Comparison  

NASA Astrophysics Data System (ADS)

NiTi shape memory alloys (SMA) are used for a variety of applications including medical implants and tools as well as actuators, making use of their unique properties. However, due to the hardness and strength, in combination with the high elasticity of the material, the machining of components can be challenging. The most common machining techniques used today are laser cutting and electrical discharge machining (EDM). In this study, we report on the machining of small structures into binary NiTi sheets, applying alternative processing methods being well-established for other metallic materials. Our results indicate that water jet machining and micro milling can be used to machine delicate structures, even in very thin NiTi sheets. Further work is required to optimize the cut quality and the machining speed in order to increase the cost-effectiveness and to make both methods more competitive.

Frotscher, M.; Kahleyss, F.; Simon, T.; Biermann, D.; Eggeler, G.

2011-07-01

88

Cyclotron targets and production technologies used for radiopharmaceuticals in NPI  

NASA Astrophysics Data System (ADS)

This paper deals with some technical aspects of the development and production of cyclotronmade radiopharmaceuticals (excluding PET). In this field, nuclear chemistry and pharmacy are in a close contact; therefore, requirements of the both should be taken into account. The principles of cyclotron targetry, separation/recovery of materials and synthesis of active substances are given, as well as issues connected with formulation of pharmaceutical forms. As the radiopharmaceuticals should fulfil the requirements on in vivo preparations, there exist a variety of demands pertaining to Good Manufacturing Practice (GMP) concept, which is also briefly discussed. A typical production chain is presented and practical examples of real technologies based on cyclotron-made radionuclides are given as they have been used in Nuclear Physics Institute of CAS (NPI). Special attention is devoted to the technology of enriched cyclotron targets. Frequently used medicinal products employing cyclotron-produced active substances are characterised (Rb/Kr generators, 123I-labelled MIBG, OIH and MAB's). The cyclotron produced radioactive implants for transluminal coronary angioplasty (radioactive stents) are introduced as an example of a medical device developed for therapeutic application.

Fišer, M.; Kopi?ka, K.; Hradilek, P.; Han?, P.; Lebeda, O.; Pánek, J.; Vognar, M.

2003-01-01

89

Helium cyclotron resonance within the earth's magnetosphere  

SciTech Connect

A histogram of electromagnetic Alfven/ion cyclotron wave frequencies, sampled within the geostationary enviroment and normalized by the equatorial proton cyclotron frequency, shows a dramatic gap centered near the helium (He/sup +/) cyclotron frequency. Also, strongly cyclotron phase bunched helium ions (20--200 eV) have been observed directly within the vicinity of wave environments. These observations are interpreted as resulting from the absorption of the waves through cyclotron resonance by cool ambient populations of helium ions.

Mauk, B.H.; McIlwain, C.E.; McPherron, R.L.

1981-01-01

90

EC-5 fifth international workshop on electron cyclotron emission and electron cyclotron heating  

SciTech Connect

This report contains papers on the following topics: electron cyclotron emission measurements; electron cyclotron emission theory; electron cyclotron heating; gyrotron development; and ECH systems and waveguide development. These paper have been indexed separately elsewhere. (LSP).

Prater, R.; Lohr, J. [eds.

1985-12-31

91

Use of cyclotrons in medicine  

Microsoft Academic Search

Cyclotrons are versatile ion-accelerating machines which find many applications in medicine. In this short review their use in hadron therapy is briefly discussed. Proton therapy is gaining significance because of its capability to treat deep-lying tumours. A strong area of application of cyclotrons involves the production of short-lived neutron deficient radiotracers for use in emission tomography, especially positron emission tomography.

S. M. Qaim

2004-01-01

92

Proton Beam Therapy for Patients With Medically Inoperable Stage I Non–Small-Cell Lung Cancer at the University of Tsukuba  

Microsoft Academic Search

Purpose: To evaluate in a retrospective review the role of proton beam therapy for patients with medically inoperable Stage I non-small-cell lung cancer (NSCLC). Patients and Methods: From November 2001 to July 2008, 55 medically inoperable patients with Stage I NSCLC were treated with proton beam therapy. A total of 58 (T1\\/T2, 30\\/28) tumors were treated. The median age of

Hidetsugu Nakayama; Shinji Sugahara; Mari Tokita; Hiroaki Satoh; Koji Tsuboi; Shigemi Ishikawa; Koichi Tokuuye

2010-01-01

93

H Exp - Cyclotrons for Radioisotope Production.  

National Technical Information Service (NTIS)

Over the past few years H exp - cyclotrons have been introduced as powerful radioisotope producers. Four of these machines, supplied by The Cyclotron Corporation of Berkeley, California, are now in regular operation in the US, Britain, Germany and Canada....

J. J. Burgerjon

1984-01-01

94

Engaging with economic evaluation methods: insights from small and medium enterprises in the UK medical devices industry after training workshops  

PubMed Central

Background With increased governmental interest in value assessment of technologies and where medical device manufacturers are finding it increasingly necessary to become more familiar with economic evaluation methods, the study sought to explore the levels of health economics knowledge within small and medium-sized enterprises (SMEs) and to scope strategies they employ to demonstrate the value of their products to purchasers. Methods A short questionnaire was completed by participants attending one of five workshops on product development in the medical device sector that took place in England between 2007 and 2011. From all responses obtained, a large proportion of participants were based in SMEs (N?=?43), and these responses were used for the analysis. Statistical analysis using non-parametric tests was performed on questions with approximately interval scales. Qualitative data from participant responses were analysed to reveal emerging themes. Results The questionnaire results revealed that 60% of SME participants (mostly company directors or managers, including product or project managers) rated themselves as having low or no knowledge of health economics prior to the workshops but the rest professed at least medium knowledge. Clinical trials and cost analyses or cost-effectiveness studies were the most highly cited means by which SMEs aim to demonstrate value of products to purchasers. Purchasers were perceived to place most importance on factors of safety, expert opinion, cost-effectiveness and price. However many companies did not utilise formal decision-making tools to prioritise these factors. There was no significant dependence of the use of decision-making tools in general with respect to professed knowledge of health economics methods. SMEs did not state a preference for any particular aspect of potential value when deciding whether to develop a product. A majority of SMEs stated they would use a health economics tool. Research and development teams or marketing and sales departments would most likely use one. Conclusion This study points to the need for further research into the education requirements of SMEs in the area of Health Technology Assessment (HTA) and also for investigation into how SMEs engage with existing HTA processes as required by assessors such as NICE. PMID:22943625

2012-01-01

95

Improved precision and accuracy for high-performance liquid chromatography/Fourier transform ion cyclotron resonance mass spectrometric exact mass measurement of small molecules from the simultaneous and controlled introduction of internal calibrants via a second electrospray nebuliser.  

PubMed

The use of a second electrospray nebuliser has proved to be highly successful for exact mass measurement during high-performance liquid chromatography/Fourier transform ion cyclotron resonance mass spectrometry (HPLC/FTICRMS). Much improved accuracy and precision of mass measurement were afforded by the introduction of the internal calibration solution, thus overcoming space charge issues due to the lack of control over relative ion abundances of the species eluting from the HPLC column. Further, issues of suppression of ionisation, observed when using a T-piece method, are addressed and this simple system has significant benefits over other more elaborate approaches providing data that compares very favourably with these other approaches. The technique is robust, flexible and transferable and can be used in conjunction with HPLC, infusion or flow injection analysis (FIA) to provide constant internal calibration signals to allow routine, accurate and precise mass measurements to be recorded. PMID:15543531

Herniman, Julie M; Bristow, Tony W T; O'Connor, Gavin; Jarvis, Jackie; Langley, G John

2004-01-01

96

Web-based technology: its effects on small group "problem-based learning" interactions in a professional veterinary medical program.  

PubMed

The objective of this investigation was to ascertain whether and how the introduction of a new technology (WebCT) influenced faculty teaching styles while facilitating small group problem-based learning (PBL) sessions in a professional veterinary medical (PVM) program. The following questions guided the study: (1) How does the use of technology affect faculty teaching behaviors? (2) Do the facilitators' interactions with WebCT technology change over the course of one semester? (3) What is the perceived impact of WebCT on facilitators' role in PBL? The study employed a combination of qualitative (case study) and semi-quantitative (survey) methods to explore these issues. Nine clinical sciences faculty members, leading a total of six PBL groups, were observed over the course of an academic semester for a total of 20 instructional sessions. The qualitative data gathered by observing faculty as they facilitated PBL sessions yielded three major themes: (1) How do PBL facilitators adapt to the addition of WebCT technology? (2) Does this technology affect teaching? and (3) How do PBL facilitators interact with their students and each other over the course of a semester? No direct evidence was found to suggest that use of WebCT affected teaching behaviors (e.g., student-centered vs. teacher-centered instruction). However, all facilitators showed a moderate increase in comfort with the technology during the semester, and one participant showed remarkable gains in technology skills. The teaching theme provided insight into how facilitators foster learning in a PBL setting as compared to a traditional lecture. A high degree of variability in teaching styles was observed, but individuals' styles tended to remain stable over the course of the semester. Nevertheless, all facilitators interacted similarly with students, in a more caring and approachable manner, when compared to the classroom or clinic atmospheres. PMID:15834826

Schoenfeld-Tacher, Regina; Bright, Janice M; McConnell, Sherry L; Marley, Wanda S; Kogan, Lori R

2005-01-01

97

Cyclotron subharmonics resonant (CSR) heating  

NASA Astrophysics Data System (ADS)

Corresponding to the experiment done with the JIPPT-II-U device [Phys. Rev. Lett. 54, 2339 (1985)], the cyclotron subharmonics resonant (CSR) heating mechanism is studied using particle simulation codes with an emphasis on the relationship between CSR and the nonlinear Landau damping.

Abe, Hirotada

1994-08-01

98

High brightness 50 MeV Cyclotron for Accelerator-Driven Subcritical Fission  

NASA Astrophysics Data System (ADS)

The Accelerator Research Lab at Texas A&M University is developing new accelerator technology for a high-brightness, high-current cyclotron with capabilities that will be beneficial for applications to accelerator-driven subcritical fission, medical isotope production, and proton therapy. As a first embodiment of the technology, we are developing a detailed design for TAMU-50, a 50 MeV, 5 mA proton cyclotron with high beam brightness. In this presentation we present devices and beamline components for injection, extraction, controls and diagnostics. We emphasize the system integration and implementation of TAMU-50 for production of medical radioisotopes.

Assadi, Saeed; Badgley, Karie; Mann, Thomas; McIntyre, Peter; Pogue, Nathaniel; Sattarov, Akhdiyor

2011-10-01

99

The cyclotron laboratory and the RFQ accelerator in Bern  

NASA Astrophysics Data System (ADS)

Two proton accelerators have been recently put in operation in Bern: an 18 MeV cyclotron and a 2 MeV RFQ linac. The commercial IBA 18/18 cyclotron, equipped with a specifically conceived 6 m long external beam line ending in a separate bunker, will provide beams for routine 18-F and other PET radioisotope production as well as for novel detector, radiation biophysics, radioprotection, radiochemistry and radiopharmacy developments. The accelerator is embedded into a complex building hosting two physics laboratories and four Good Manufacturing Practice (GMP) laboratories. This project is the result of a successful collaboration between the Inselspital, the University of Bern and private investors, aiming at the constitution of a combined medical and research centre able to provide the most cutting-edge technologies in medical imaging and cancer radiation therapy. The cyclotron is complemented by the RFQ with the primary goals of elemental analysis via Particle Induced Gamma Emission (PIGE), and the detection of potentially dangerous materials with high nitrogen content using the Gamma-Resonant Nuclear Absorption (GRNA) technique. In this context, beam instrumentation devices have been developed, in particular an innovative beam profile monitor based on doped silica fibres and a setup for emittance measurements using the pepper-pot technique. On this basis, the establishment of a proton therapy centre on the campus of the Inselspital is in the phase of advanced study.

Braccini, S.; Ereditato, A.; Kreslo, I.; Nirkko, M.; Scampoli, P.; von Bremen, K.; Weber, M.

2013-07-01

100

The cyclotron laboratory and the RFQ accelerator in Bern  

SciTech Connect

Two proton accelerators have been recently put in operation in Bern: an 18 MeV cyclotron and a 2 MeV RFQ linac. The commercial IBA 18/18 cyclotron, equipped with a specifically conceived 6 m long external beam line ending in a separate bunker, will provide beams for routine 18-F and other PET radioisotope production as well as for novel detector, radiation biophysics, radioprotection, radiochemistry and radiopharmacy developments. The accelerator is embedded into a complex building hosting two physics laboratories and four Good Manufacturing Practice (GMP) laboratories. This project is the result of a successful collaboration between the Inselspital, the University of Bern and private investors, aiming at the constitution of a combined medical and research centre able to provide the most cutting-edge technologies in medical imaging and cancer radiation therapy. The cyclotron is complemented by the RFQ with the primary goals of elemental analysis via Particle Induced Gamma Emission (PIGE), and the detection of potentially dangerous materials with high nitrogen content using the Gamma-Resonant Nuclear Absorption (GRNA) technique. In this context, beam instrumentation devices have been developed, in particular an innovative beam profile monitor based on doped silica fibres and a setup for emittance measurements using the pepper-pot technique. On this basis, the establishment of a proton therapy centre on the campus of the Inselspital is in the phase of advanced study.

Braccini, S.; Ereditato, A.; Kreslo, I.; Nirkko, M.; Weber, M. [Albert Einstein Center for Fundamental Physics, Laboratory for High Energy Physics (LHEP), University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Scampoli, P. [Albert Einstein Center for Fundamental Physics, Laboratory for High Energy Physics (LHEP), University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland and Department of Physical Sciences, University Federico II, Via Cintia, I-60126 Napoli (Italy); Bremen, K. von [SWAN Isotopen AG, Inselspital, CH-3010 Bern (Switzerland)

2013-07-18

101

Pharmacist Staffing and the Use of Technology in Small Rural Hospitals: Implications for Medication Safety. Working Paper No. 1.  

National Technical Information Service (NTIS)

This paper reports the results of a national study that assesses the capacity of rural hospitals to implement medication safety practices, with particular focus on pharmacist staffing and the availability of technology. The primary data for the project wa...

G. Davidson, I. Moscovice, M. M. Casey

2005-01-01

102

Production of the PET bone agent (18)F-fluoride ion, simultaneously with (18)F-FDG by a single run of the medical cyclotron with minimal radiation exposure- a novel technique.  

PubMed

Our aim was to establish an easy and convenient procedure for the preparation of fluorine-18-sodium fluoride ((18)F-NaF) for bone positron emission tomography (PET) during routine (18)F-FDG production using the Explora FDG4 radiochemistry module (EFRM) by single run of Cyclotron with negligible radiation exposure. We compared three techniques for (18)F-NaF production during routine PET radiochemistry at our setup. In one method we used synthesis module and in other two methods we did not. In the first and third method, F-18 was directly extracted from the V-vial and in the second method, (18)F-NaF was extracted by post processing from the EFRM. In the first method, F-18 was extracted directly from V-vial manually by opening the V-vial cap. In the second method, Explora FDG-4 Module was used. First, F-18 was transferred from the V-vial. Then, after post processing in EFRM, pure F-18 was obtained in the product vial. In the third method, pure F-18 was obtained in the product vial with the help of a mechanical robotic arm. The above were followed by routine quality control of (18)F-NaF produced by each method. Results of quality control of the (18)F-NaF obtained by all three methods satisfied all parameters prescribed by the United States Pharmacopeia (USP) and the British Pharmacopeia (BP) including biological, physical and chemical specifications. The radiochemical purity was 98.5±1.5% with Rf 0.006. The level of Kryptofix-222 (K222) in (18)F-NaF was within the prescribed limit. Mean pH of (18)F-NaF was 6.0±1.5. The exposure rate around the hot cell was negligible. In conclusion, from the results it was obvious that by our method number three (18)F-NaF was directly obtained from the V-vial using mechanical robotic arms. This method was the most appropriate with minimized radiation exposure to the handling Radiochemist and was also saving time as compared to the other two methods. PMID:25097896

Kumar, Rajeev; Sonkawade, Rajendra G; Tripathi, Madhavi; Sharma, Punit; Gupta, Priyanka; Kumar, Praveen; Pandey, Anil K; Bal, Chandrasekhar; Damle, Nishikant Avinash; Bandopadhayaya, Gurupad

2014-01-01

103

TRIUMF cyclotron vacuum system refurbishing  

NASA Astrophysics Data System (ADS)

The cyclotron at TRIUMF was commissioned to full energy in 1974. The volume of the cyclotron vacuum tank is about 100 m3 and it operates at 5×10-8 Torr pressure during beam production. The pumping is mainly based on a Phillips B-20 cryogenerator (Stirling cycle 4-cylinder engine). The cryogenerator supplies helium gas at 16 K and 70 K to cryopanels in the tank. The decreasing reliability of the B-20 and demanding maintenance requirements triggered the decision to completely overhaul or replace the cryogenerator. Replacement with the LINDE-1630 helium refrigerator was found to be the most attractive (technically and economically) option. The details of the proposal with installation of the helium refrigerator and with a continuous flow liquid nitrogen shield cooling system are presented.

Sekachev, I.

2008-03-01

104

Small Group Learning in Medical Education: A Second Look at the Springer, Stanne, and Donovan Meta-Analysis.  

ERIC Educational Resources Information Center

Reviews the studies on which a meta-analysis by Springer, Stanne, and Donovan (1999) were based; the meta-analysis had concluded that small group learning in science, mathematics, engineering, and technology education is effective. Concludes that the meta-analysis' call for more widespread implementation of small group learning is not supported.…

Colliver, Jerry A.; Feltovich, Paul J.; Verhulst, Steven J.

2003-01-01

105

Fluid theory of beam spiraling in high intensity cyclotrons  

NASA Astrophysics Data System (ADS)

Novel uses of cyclotrons for basic science, national security and medical therapy applications require the production of beams with ever higher intensities. At these high intensities, uncontrolled beam loss must be minimized. To satisfy the stringent beam loss criteria, it is crucial to have a detailed understanding of the beam dynamics in high intensity cyclotrons, and more specifically, an understanding of the effects of space charge on the dynamics. Using a two-dimensional fluid description, we investigate the nonlinear radial-longitudinal dynamics of intense beams in cyclotrons. With a multiscale analysis separating the time scale associated with the betatron motion and the slower time scale associated with space-charge effects, we show that the longitudinal-radial vortex motion can be understood in the frame moving with the charged beam as the nonlinear advection of the beam by the ExB velocity field, where E is the electric field due to the space charge and B is the external magnetic field. This interpretation provides simple explanations for the stability of round beams and for the development of spiral halos in elongated beams. By numerically solving the advection equation, we show that it is also in quantitative agreement with results obtained in PIC simulations.

Cerfon, Antoine; Parra, Felix; Freidberg, Jeffrey

2012-10-01

106

Cyclotron Line Measurements with INTEGRAL  

NASA Technical Reports Server (NTRS)

Due to its broadband energy coverage, INTEGRAL has made important contributions to observing and interpreting cyclotron lines, which are present in the 10-100 keV range of a sample of accreting pulsars. In these systems photons with energies fulfilling the resonance condition inelastically Compton scatter off electrons quantized in the accretion column above the neutron star's magnetic pole(s). This process gives rise to the broad, absorption-like lines or 'cyclotron resonant scattering features' (CRSF). The observed lines allow to directly measure the B-fields of these sources, resulting in values of a few times 1E12G. In this overview I will present recent highlights regarding CRSF observations as well as discuss current ideas and models for the physical conditions in the accretion column. Among the former are the stability of the spectrum of Vela X-1 during giant flares in 2003, the observation of three cyclotron lines during the 2004 outburst of V0332+53, the confirmation of the fundamental line at approximately 45 keV during a 2005 normal outburst of A0535-26, and the simultaneous detection of the two lines in the dipping source 4U 1907+09 (for which also a torque reversal was detected for the first time). Through these and other observations it has become increasingly apparent that two types of observations can potentially be used to constrain the accretion column geometry: the determination of energy ratios for multiple harmonic lines (only two sources with greater than 2 lines are known), was well as the evolution of the fundamental line centroid, which, for different sources, may or may not be correlated with flux. Furthermore, first steps have been taken away from the usual phenomenological description of the lines, towards a physical approach based on self-consistent CRSF modeling. Initial applications are presented.

Pottschmidt, K.; Kreykenbohm, I.; Caballero, I.; Fritz, S.; Schoenherr, G.; Kretschmar, P.; Wilms, J.; McBride, V. A.; Suchy, S.; Rothschild, R. E.

2008-01-01

107

Lawrence's Legacy : Seaborg's Cyclotron - The 88-Inch Cyclotron turns 40  

NASA Astrophysics Data System (ADS)

In 1958, Sputnik had recently been launched by the Russians, leading to worry in Congress and increased funding for science and technology. Ernest Lawrence was director of the "Rad Lab" at Berkeley. Another Nobel Prize winner, Glenn Seaborg, was Associate Laboratory Director and Director of the Nuclear Chemistry Division. In this atmosphere, Lawrence was phoned by commissioners of the Atomic Energy Commission and asked what they could do for Seaborg, "because he did such a fine job of setting up the chemistry for extracting plutonium from spent reactor fuel" [1]. In this informal way, the 90-Inch (eventually 88-Inch) Cyclotron became a line item in the federal budget at a cost of 3M (later increased to 5M). The 88-Inch Cyclotron achieved first internal beam on Dec. 12, 1961 and first external beam in May 1962. Forty years later it is still going strong. Pieced together from interviews with the retirees who built it, Rad Lab reports and archives from the Seaborg and Lawrence collections, the story of its design and construction - on-time and under-budget - provides a glimpse into the early days of big science. [1] remarks made by Elmer Kelly, "Physicist-in-charge' of the project on the occasion of the 40th anniversary celebration.

McMahan, Margaret; Clark, David

2003-04-01

108

Orbit dynamics in isochronous cyclotrons  

SciTech Connect

Acceleration of heavy ions in an isochronous cyclotron can lead to a ..nu../sub r/-value near unity for many turns. In ORIC, several departures from 3-fold symmetry unfortunately exist, so that a complex resonant behavior may lead to beam loss. To study these questions, a program has been initiated with the aim of devising and using very efficient algorithms for calculating the motion of ions during acceleration. The eikonal function was chosen as the basis for these studies, with methods and some results here described.

Welton, T.A.; Nichols, T.

1981-01-01

109

Cyclotron radiation losses in subcompact tori  

Microsoft Academic Search

Subcompact tori such as the field reversed mirror (FRM) have a relatively large surface to volume ratio. This has raised concern that in advanced fuel devices cyclotron losses could prevent their viability as reactors. Indeed the cyclotron radiation produced is several times the fusion power. However, due to reabsorption in the FRM plasma, it turns out that less than 7%

W. Tetley; G. Miley

1980-01-01

110

Assistant Professor, Small Animal Critical Care/ Emergency Medicine Department of Clinical Sciences, James L. Voss Veterinary Medical Center  

E-print Network

Assistant Professor, Small Animal Critical Care/ Emergency Medicine Department of Clinical Sciences) at the Assistant Professor level in the Department of Clinical Sciences. Qualifications · DVM or equivalent/or continuous renal replacement therapy program is desirable. Specific Responsibilities Teaching · Clinical

Birner, Thomas

111

Results from an exploratory study to identify the factors that contribute to success for UK medical device small- and medium-sized enterprises.  

PubMed

This paper reports the results from an exploratory study that sets out to identify and compare the strategic approaches and patterns of business practice employed by 14 UK small- and medium-sized enterprises to achieve success in the medical device sector of the health-care industry. An interview-based survey was used to construct individual case studies of the medical device technology (MDT) companies. A cross-case analysis was performed to search for patterns and themes that cut across these individual cases. Exploratory results revealed the heterogeneity of MDT companies and the distinctive features of the MDT innovation process that emphasize the importance of a strategic approach for achieving milestones in the product development and exploitation process and for creating value for the company and its stakeholders. Recognizing the heterogeneity of MDT companies, these exploratory findings call for further investigation to understand better the influence of components of the MDT innovation process on the commercialization life cycle and value trajectory. This is required to assist start-up or spin-out MDT companies in the UK and worldwide to navigate the critical transitions that determine access to financial and consumer markets and enhance the potential to build a successful business. This will be important not only for bioscience-based companies but also for engineering-based companies aiming to convert their activities into medical devices and the health- and social-care market. PMID:18756690

Hourd, P C; Williams, D J

2008-07-01

112

Hypofractionated radical radiotherapy in elderly patients with medically inoperable stage I–II non-small-cell lung cancer  

Microsoft Academic Search

We described the results of a hypofractionated regimen (HFRT) in a cohort of elderly patients (36 subjects) with stage I–II non-small-cell-lung cancer (NSCLC), tumor size?3cm and ineligible for surgery. HFRT was delivered in 20 daily fractions of 3Gy per fraction with a total dose of 60Gy. The median PTV was 145cm3. The primary purpose of study was to estimate the

Pierluigi Bonfili; Mario Di Staso; Giovanni Luca Gravina; Pietro Franzese; Sergio Buonopane; Francesca Soldà; Claudio Festuccia; Vincenzo Tombolini

2010-01-01

113

Cost-Effectiveness Analysis of Stereotactic Body Radiotherapy and Radiofrequency Ablation for Medically Inoperable, Early-Stage Non-Small Cell Lung Cancer  

SciTech Connect

Purpose: The standard management of medically inoperable Stage I non-small-cell lung cancer (NSCLC) conventionally has been fractionated three-dimensional conformal radiation therapy (3D-CRT). The relatively poor local control rate and inconvenience associated with this therapy have prompted the development of stereotactic body radiotherapy (SBRT), a technique that delivers very high doses of irradiation typically over 3 to 5 sessions. Radiofrequency ablation (RFA) has also been investigated as a less costly, single-day therapy that thermally ablates small, peripheral tumors. The cost-effectiveness of these three techniques has never been compared. Methods and Materials: We developed a Markov model to describe health states of 65-year-old men with medically inoperable NSCLC after treatment with 3D-CRT, SBRT, and RFA. Given their frail state, patients were assumed to receive supportive care after recurrence. Utility values, recurrence risks, and costs were adapted from the literature. Sensitivity analyses were performed to model uncertainty in these parameters. Results: The incremental cost-effectiveness ratio for SBRT over 3D-CRT was $6,000/quality-adjusted life-year, and the incremental cost-effectiveness ratio for SBRT over RFA was $14,100/quality-adjusted life-year. One-way sensitivity analysis showed that the results were robust across a range of tumor sizes, patient utility values, and costs. This result was confirmed with probabilistic sensitivity analyses that varied local control rates and utilities. Conclusion: In comparison to 3D-CRT and RFA, SBRT was the most cost-effective treatment for medically inoperable NSCLC over a wide range of treatment and disease assumptions. On the basis of efficacy and cost, SBRT should be the primary treatment approach for this disease.

Sher, David J., E-mail: dsher@lroc.harvard.edu [Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Boston, MA (United States); Center for Outcomes and Policy Research, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Boston, MA (United States); Wee, Jon O. [Department of Thoracic Surgery, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Boston, MA (United States); Punglia, Rinaa S. [Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Boston, MA (United States); Center for Outcomes and Policy Research, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Boston, MA (United States)

2011-12-01

114

Design study of an ultra-compact superconducting cyclotron for isotope production  

NASA Astrophysics Data System (ADS)

A 12.5 MeV, 25 ?A, proton compact superconducting cyclotron for medical isotope production has been designed and is currently in fabrication. The machine is initially aimed at producing 13N ammonia for Positron Emission Tomography (PET) cardiology applications. With an ultra-compact size and cost-effective price point, this system will offer clinicians unprecedented access to the preferred radiopharmaceutical isotope for cardiac PET imaging. A systems approach that carefully balanced the subsystem requirements coupled to precise beam dynamics calculations was followed. The system is designed to irradiate a liquid target internal to the cyclotron and to minimize the need for radiation shielding. The main parameters of the cyclotron, its design, and principal steps of the development work are presented here.

Smirnov, V.; Vorozhtsov, S.; Vincent, J.

2014-11-01

115

Radio-frequency system of the KIRAMS-30 cyclotron for RI mass production  

NASA Astrophysics Data System (ADS)

The KHIMA (Korea Heavy Ion Medical Accelerator) had developed the KIRAMS-30 cyclotron in collaboration with the ARTI (Advanced Radiation Technology Institute). This cyclotron is able to accelerate proton for the mass production of radioisotopes. It is designed to use two normal conduct RF cavities. The resonant frequency of the ion is 15.99 MHz because of the magnet design and the beam dynamics. The RF frequency is 63.96 MHz because of the 4 th harmonic number. By using computer simulation codes, we estimated the principle design parameters of the RF system, we simulated the electric field distribution. In this paper, we present the design features, the results of quality assessment tests for the RF system, and important issues taken into consideration when designing such a cyclotron.

Jung, In Su; Park, Yeunsoo; Kang, Joonsun; Kang, Gun Uk; An, Dong Hyun; Hahn, Garam; Hong, Bong Hwan; Hur, Min Goo; Cho, Jun Dong; Kim, Moon-Hyun; Kwon, Key Ho

2012-07-01

116

A 160 cm Synchro and Variable Energy Ordinary Cyclotron  

Microsoft Academic Search

A 160-cm cyclotron which can be used as a variable energy ordinary ; cyclotron as well as a synchro-cyclotron by changing the dee-system and the ; oscillator system is described. As an ordinary cyclotron it can produce protons ; of any desired energy between 7.5 and 15 Mev, deuterons between 15 and 21 Mev, ; and alpha particles between 30

Seishi Kikuchi; Itaru Nonaka; Hiroshi Ikeda; Hiroo Kumagai; Yoshio Saji; Junpei Sanada; Shigeki Suwa; Akira Isoya; Izuo Hayashi; Kazuhisa Matsuda; Hisashi Yamaguchi; Takashi Mikumo; K. Nishimura; Takashi Karasawa; Shinsaku Kobayashi; Ken Kikuchi; Satoru Ito; Arata Suzuki; Seiichiro Takeuchi; Hirotsugu Ogawa

1960-01-01

117

Nonlinear evolution of electromagnetic ion cyclotron waves  

SciTech Connect

Hybrid Vlasov-Fourier modeling is used to investigate the nonlinear evolution of electromagnetic ion cyclotron (EMIC) waves driven by proton temperature anisotropy in plasmas with a population of He{sup +} ions and a cold proton background. In the pure proton-electron plasma, most of the free energy is converted into high-amplitude waves and currents. In the nonlinear stage, within a few hundred proton gyroperiods after the saturation, the wave spectrum shifts toward lower wave numbers and frequencies, from {omega}{approx}0.6{Omega}{sub p} to below {omega}{approx}0.25{Omega}{sub p}. In the presence of even a small population of He{sup +} ions almost all of the free energy is used in He{sup +} heating. The wave activity in the saturated state moves from the linearly unstable upper branch to the linearly stable lower one. In the presence of a background of cold protons, the waves can propagate in the frequency stop-band. Our results demonstrate that linear stability theory cannot be used to estimate the characteristics of the expected saturated wave spectra in the terrestrial magnetosphere. Significantly, our nonlinear simulations produce wave spectra which are in close agreement with the EMIC waves observed in situ by satellites as well as by ground-based magnetometers positioned at the ends of the magnetic field lines.

Silin, I.; Sydora, R. D.; Mann, I. R.; Sauer, K. [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2G7 (Canada); Mace, R. L. [School of Physics, University of KwaZulu-Natal, Durban 4000 (South Africa)

2011-04-15

118

RCNP cyclotron facility and application program  

NASA Astrophysics Data System (ADS)

The RCNP cyclotron cascade system consists of K140 AVF cyclotron and K400 ring cyclotron and is providing high quality beams for various experiments. Three kinds of neutron sources are developed for applications as well as fundamental physics. They provide monoenergetic neutrons at 10-400 MeV, white neutrons with the same energy spectra as terrestrial neutrons on the earth, and ultra cold neutrons with energies below 210 neV. There are increasing demands for high intensity beams and even to improve the quality. In order to increase the physics research opportunities, a new injector cyclotron is proposed, which has four separated sector magnets and two accelerating cavities. Sector magnets are designed to use High Temperature Superconducting (HTS) wire. At RCNP, we have been developing magnets with HTS wires for a decade.

Hatanaka, Kichiji

2013-05-01

119

Method and apparatuses for ion cyclotron spectrometry  

DOEpatents

An ion cyclotron spectrometer may include a vacuum chamber that extends at least along a z-axis and means for producing a magnetic field within the vacuum chamber so that a magnetic field vector is generally parallel to the z-axis. The ion cyclotron spectrometer may also include means for producing a trapping electric field within the vacuum chamber. The trapping electric field may comprise a field potential that, when taken in cross-section along the z-axis, includes at least one section that is concave down and at least one section that is concave up so that ions traversing the field potential experience a net magnetron effect on a cyclotron frequency of the ions that is substantially equal to zero. Other apparatuses and a method for performing ion cyclotron spectrometry are also disclosed herein.

Dahl, David A. (Idaho Falls, ID); Scott, Jill R. (Idaho Falls, ID); McJunkin, Timothy R. (Idaho Falls, ID)

2012-03-06

120

Toxicity and Patterns of Failure of Adaptive/Ablative Proton Therapy for Early-Stage, Medically Inoperable Non-Small Cell Lung Cancer  

SciTech Connect

Purpose: To analyze the toxicity and patterns of failure of proton therapy given in ablative doses for medically inoperable early-stage non-small cell lung cancer (NSCLC). Methods and Materials: Eighteen patients with medically inoperable T1N0M0 (central location) or T2-3N0M0 (any location) NSCLC were treated with proton therapy at 87.5 Gy (relative biological effectiveness) at 2.5 Gy /fraction in this Phase I/II study. All patients underwent treatment simulation with four-dimensional CT; internal gross tumor volumes were delineated on maximal intensity projection images and modified by visual verification of the target volume in 10 breathing phases. The internal gross tumor volumes with maximal intensity projection density was used to design compensators and apertures to account for tumor motion. Therapy consisted of passively scattered protons. All patients underwent repeat four-dimensional CT simulations during treatment to assess the need for adaptive replanning. Results: At a median follow-up time of 16.3 months (range, 4.8-36.3 months), no patient had experienced Grade 4 or 5 toxicity. The most common adverse effect was dermatitis (Grade 2, 67%; Grade 3, 17%), followed by Grade 2 fatigue (44%), Grade 2 pneumonitis (11%), Grade 2 esophagitis (6%), and Grade 2 chest wall pain (6%). Rates of local control were 88.9%, regional lymph node failure 11.1%, and distant metastasis 27.8%. Twelve patients (67%) were still alive at the last follow-up; five had died of metastatic disease and one of preexisting cardiac disease. Conclusions: Proton therapy to ablative doses is well tolerated and produces promising local control rates for medically inoperable early-stage NSCLC.

Chang, Joe Y., E-mail: jychang@mdanderson.org [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Komaki, Ritsuko; Wen, Hong Y.; De Gracia, Beth; Bluett, Jaques B.; McAleer, Mary F. [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Swisher, Stephen G. [Department of Thoracic/Cardiovascular Surgery, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Gillin, Michael; Mohan, Radhe [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Cox, James D. [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)

2011-08-01

121

Building 211 cyclotron characterization survey report  

SciTech Connect

The Building 211 Cyclotron Characterization Survey includes an assessment of the radioactive and chemical inventory of materials stored within the facility; an evaluation of the relative distribution of accelerator-produced activation products within various cyclotron components and adjacent structures; measurement of the radiation fields throughout the facility; measurement and assessment of internal and external radioactive surface contamination on various equipment, facility structures, and air-handling systems; and an assessment of lead (Pb) paint and asbestos hazards within the facility.

NONE

1998-03-30

122

Intermittent Heating of the Solar Corona by Heat Flux-generated Ion Cyclotron Waves  

Microsoft Academic Search

Recently, we suggested that the source of ion heating in solar coronal holes is small-scale reconnection events (microflares) at the coronal base. The microflares launch intermittent heat flux up into the corona exciting ion cyclotron waves through a plasma microinstability. The ions are heated by these waves during the microflare bursts and then evolve with no energy input between the

S. A. Markovskii; Joseph V. Hollweg

2004-01-01

123

An all permanent magnet electron cyclotron resonance ion source for heavy ion therapy.  

PubMed

A high charge state all permanent Electron Cyclotron Resonance ion source, Lanzhou All Permanent ECR ion source no. 3-LAPECR3, has been successfully built at IMP in 2012, which will serve as the ion injector of the Heavy Ion Medical Machine (HIMM) project. As a commercial device, LAPECR3 features a compact structure, small size, and low cost. According to HIMM scenario more than 100 e?A of C(5+) ion beam should be extracted from the ion source, and the beam emittance better than 75 ?*mm*mrad. In recent commissioning, about 120 e?A of C(5+) ion beam was got when work gas was CH4 while about 262 e?A of C(5+) ion beam was obtained when work gas was C2H2 gas. The design and construction of the ion source and its low-energy transportation beam line, and the preliminary commissioning results will be presented in detail in this paper. PMID:24593539

Cao, Yun; Li, Jia Qing; Sun, Liang Ting; Zhang, Xue Zhen; Feng, Yu Cheng; Wang, Hui; Ma, Bao Hua; Li, Xi Xia

2014-02-01

124

Mid-term results of 17-mm St. Jude Medical Regent prosthetic valves in elder patients with small aortic annuli: comparison with 19-mm bioprosthetic valves.  

PubMed

This study was designed to compare the mid-term outcomes after aortic valve replacement (AVR) between 17-mm mechanical heart valves (MV) and 19-mm bioprosthetic valves (BV) in elderly patients with small aortic annuli. Between 2000 and 2011, 127 consecutive patients (mean age 79 years; 87 % female) underwent AVR for aortic valve stenosis with a small aortic annulus. 19-mm BV (n = 67) was implanted. When the 19-mm BV did not fit the annulus, 17-mm St. Jude Medical Regent prosthetic mechanical valve (n = 60) was used instead of an aortic root-enlargement procedure. The follow-up rate was 94.0 % in the BV group, and 98.5 % in the MV group. No significant differences in survival rate and valve-related complications were found between the 2 groups. In-hospital mortality rates were 1.5 % (n = 1) in the BV group and 5.0 % (n = 3) in the MV group. Late mortality rates were 3.9 % per patient-years (p-y; n = 8) in the BV group, and 6.0 % per p-y (n = 10) in the MV group. Five-year Kaplan-Meier survival rates were 62 % in the BV group, and 72 % in the MV group (log-rank P = 0.280). Freedom from major adverse valve-related stroke and cerebral bleeding events was 92.5 and 98.5 % in the BV group, and 94.7 and 100 % in the MV group. AVR using 17-mm MV in elder patients with small aortic annuli provided equivalent mid-term clinical results to that with 19-mm BV. PMID:24878870

Teshima, Hideki; Ikebuchi, Masahiko; Sano, Toshikazu; Tai, Ryuta; Horio, Naohiro; Irie, Hiroyuki

2014-09-01

125

A Pilot Trial of Serial 18F-Fluorodeoxyglucose Positron Emission Tomography in Patients With Medically Inoperable Stage I Non–Small-Cell Lung Cancer Treated With Hypofractionated Stereotactic Body Radiotherapy  

Microsoft Academic Search

Purpose: Routine assessment was made of tumor metabolic activity as measured by 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in Stage I non-small-cell lung cancer (NSCLC). This report describes PET correlates prospectively collected after stereotactic body radiotherapy (SBRT) for patients with medically inoperable NSCLC. Methods and Materials: 14 consecutive patients with medically inoperable Stage I NSCLC were enrolled. All patients received

Mark A. Henderson; David J. Hoopes; James W. Fletcher; Pei-Fen Lin; Mark Tann; Constantin T. Yiannoutsos; Mark D. Williams; Achilles J. Fakiris; Ronald C. McGarry; Robert D. Timmerman

2010-01-01

126

a Low Energy Cyclotron for Radiocarbon Dating  

NASA Astrophysics Data System (ADS)

The measurement of naturally occurring radioisotopes whose half lives are less than a few hundred million years but more than a few years provides information about the temporal behavior of geologic and climatic processes, the temporal history of meteoritic bodies as well as the production mechanisms of these radioisotopes. A new extremely sensitive technique for measuring these radioisotopes at tandem Van de Graaff and cyclotron facilities has been very successful though the high cost and limited availability have been discouraging. We have built and tested a low energy cyclotron for radiocarbon dating similar in size to a conventional mass spectrometer. These tests clearly show that with the addition of a conventional ion source, the low energy cyclotron can perform the extremely high sensitivity ('14)C measurements that are now done at accelerator facilities. We found that no significant background is present when the cyclotron is tuned to accelerate ('14)C negative ions and the transmission efficiency is adequate to perform radiocarbon dating on milligram samples of carbon. The internal ion source used did not produce sufficient current to detect ('14)C directly at modern concentrations. We show how a conventional carbon negative ion source located outside the cyclotron magnet, would produce sufficient beam and provide for quick sample changing to make radiocarbon dating milligram samples with a modest laboratory instrument feasible.

Welch, James Joseph

127

A low energy cyclotron for radiocarbon dating  

NASA Astrophysics Data System (ADS)

The measurement of abundances of naturally occurring radioisotopes whose half lives are between a few years and a few hundred million years, provides information about the temporal behavior of human activity and geologic and climatic processes, the history of meteoritic bodies, and the production mechanisms of such radioisotopes. An extremely sensitive technique for measuring these radioisotopes at tandem Van de Graaff and cyclotron facilities has been very successful, though not without high cost and limited availability. We have built and tested a 35 keV cyclotron for radiocarbon dating similar in size to a conventional mass spectrometer. We found no significant background present when the cyclotron was tuned to accelerate 14C negative ions, and adequate transmission efficiency to perform radiocarbon dating on milligram samples of carbon. These tests clearly show that a low energy cyclotron can perform the extremely high sensitivity 14C measurements that are now done at accelerator facilities. The internal ion source used did not produre sufficient current to detect 14C directly at the present atmospheric 14C/ 12C concentration of 1.3×10 -12. A conventional carbon negative ion source located outside the cyclotron magnet could produce sufficient beam and provide for quick sample changing to make feasible radiocarbon dating milligram samples with a modest laboratory instrument.

Welch, J. J.; Bertsche, K. J.; Friedman, P. G.; Morris, D. E.; Muller, R. A.; Tans, P. P.

128

General Electric PETtrace cyclotron as a neutron source for boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

This research investigates the use of a PETtrace cyclotron produced by General Electric (GE) as a neutron source for boron neutron capture therapy (BNCT). The GE PETtrace was chosen for this investigation because this type of cyclotron is popular among nuclear pharmacies and clinics in many countries; it is compact and reliable; it produces protons with energies high enough to produce neutrons with appropriate energy and fluence rate for BNCT and it does not require significant changes in design to provide neutrons. In particular, the standard PETtrace 18O target is considered. The cyclotron efficiency may be significantly increased if unused neutrons produced during radioisotopes production could be utilized for other medical modalities such as BNCT at the same time. The resulting dose from the radiation emitted from the target is evaluated using the Monte Carlo radiation transport code MCNP at several depths in a brain phantom for different scattering geometries. Four different moderating materials of various thicknesses were considered: light water, carbon, heavy water, arid Fluental(TM). The fluence rate tally was used to calculate photon and neutron dose, by applying fluence rate-to-dose conversion factors. Fifteen different geometries were considered and a 30-cm thick heavy water moderator was chosen as the most suitable for BNCT with the GE PETtrace cyclotron. According to the Brookhaven Medical Research Reactor (BMRR) protocol, the maximum dose to the normal brain is set to 12.5 RBEGy, which for the conditions of using a heavy water moderator, assuming a 60 muA beam current, would be reached with a treatment time of 258 min. Results showed that using a PETtrace cyclotron in this configuration provides a therapeutic ratio of about 2.4 for depths up to 4 cm inside a brain phantom. Further increase of beam current proposed by GE should significantly improve the beam quality or the treatment time and allow treating tumors at greater depths.

Bosko, Andrey

129

The Impact of Tumor Size on Outcomes After Stereotactic Body Radiation Therapy for Medically Inoperable Early-Stage Non-Small Cell Lung Cancer  

SciTech Connect

Purpose: Stereotactic body radiation therapy for medically inoperable early-stage non-small cell lung cancer (NSCLC) offers excellent control rates. Most published series deal mainly with small (usually <4 cm), peripheral, solitary tumors. Larger tumors are associated with poorer outcomes (ie, lower control rates, higher toxicity) when treated with conventional RT. It is unclear whether SBRT is sufficiently potent to control these larger tumors. We therefore evaluated and examined the influence of tumor size on treatment outcomes after SBRT. Methods and Materials: Between October 2004 and October 2010, 185 medically inoperable patients with early (T1-T2N0M0) NSCLC were treated on a prospective research ethics board-approved single-institution protocol. Prescription doses were risk-adapted based on tumor size and location. Follow-up included prospective assessment of toxicity (as per Common Terminology Criteria for Adverse Events, version 3.0) and serial computed tomography scans. Patterns of failure, toxicity, and survival outcomes were calculated using Kaplan-Meier method, and the significance of tumor size (diameter, volume) with respect to patient, treatment, and tumor factors was tested. Results: Median follow-up was 15.2 months. Tumor size was not associated with local failure but was associated with regional failure (P=.011) and distant failure (P=.021). Poorer overall survival (P=.001), disease-free survival (P=.001), and cause-specific survival (P=.005) were also significantly associated with tumor size (with tumor volume more significant than diameter). Gross tumor volume and planning target volume were significantly associated with grade 2 or worse radiation pneumonitis. However, overall rates of grade ?3 pneumonitis were low and not significantly affected by tumor or target size. Conclusions: Currently employed stereotactic body radiation therapy dose regimens can provide safe effective local therapy even for larger solitary NSCLC tumors (up to 5.7 cm in tumor diameter or 100 cm{sup 3} in tumor volume) but are associated with more nonlocal failures as well as poorer survival. These observations suggest these patients may benefit from more extensive staging or consideration of adjuvant therapy.

Allibhai, Zishan [Department of Radiation Oncology, Princess Margaret Cancer Centre, Toronto (Canada); Taremi, Mojgan [Department of Radiation Oncology, Stronach Regional Cancer Centre, Newmarket (Canada); Bezjak, Andrea; Brade, Anthony; Hope, Andrew J.; Sun, Alexander [Department of Radiation Oncology, Princess Margaret Cancer Centre, Toronto (Canada); Cho, B.C. John, E-mail: john.cho@rmp.uhn.on.ca [Department of Radiation Oncology, Princess Margaret Cancer Centre, Toronto (Canada)

2013-12-01

130

Seventeen-millimeter St. Jude Medical Regent valve in patients with small aortic annulus: dose moderate prosthesis-patient mismatch matter?  

PubMed Central

Background The study was designed to evaluate the effects of moderate prosthesis-patient mismatch (defined as 0.65 cm2/m2?Medical Regent valve in a large series of patients, and to determine if these effects are influenced by patient confounding variables. Methods One-hundred and six patients with and without moderate prosthesis-patient mismatch early after implantation of a 17-mm Regent valve at aortic position were included. Both clinical and echocardiographic assessments were performed preoperatively, at discharge and during follow-up period (mean follow-up time 52.6?±?11.9 months). Results The prevalence of moderate prosthesis-patient mismatch was documented in 46 patients (43.4%) at discharge. During the follow-up period, no difference in the regression of left ventricular mass, decrease of transvalvular pressure gradients, mortality and prosthesis-related complications was observed between patients with and without moderate prosthesis-patient mismatch. After adjustment for several risk factors, moderate prosthesis-patient mismatch was associated with increased midterm mortality in patients with baseline left ventricular ejection fraction?small mechanical prosthesis is associated with increased mortality and adverse events in patients with pre-existing left ventricular dysfunction. Selected patients with small aortic annulus can experience satisfactory clinical improvements and midterm survival after aortic valve replacement with a 17-mm Regent valve. PMID:24438101

2014-01-01

131

Multilayer carbon foils for cyclotron beam extraction  

NASA Astrophysics Data System (ADS)

The TRIUMF Applied Technology Group operates high-power industrial cyclotrons for commercial radioisotope production. Two of these cyclotrons, TR30-1 and TR30-2, are capable of accelerating H - ions to an energy of 30 MeV and beam currents in excess of 1000 ?A. For many years, amorphous carbon foils of approximately 2.0 ?m thickness have been utilized to extract proton beams from these accelerators. Novel multilayer foils consisting of layers of amorphous and diamond-like carbon (DLC) of 2.0±0.2 ?m thickness were manufactured in-house by carbon arc and pulsed laser deposition, respectively. In the TR30 cyclotrons, the new composite foils with 25% DLC content show a three times longer lifetime than the purely amorphous foils, while maintaining their excellent physical and mechanical characteristics during irradiation.

Zeisler, Stefan K.; Jaggi, Vinder

2008-06-01

132

A room temperature electron cyclotron resonance ion source for the DC-110 cyclotron.  

PubMed

The project of the DC-110 cyclotron facility to provide applied research in the nanotechnologies (track pore membranes, surface modification of materials, etc.) has been designed by the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research (Dubna). The facility includes the isochronous cyclotron DC-110 for accelerating the intensive Ar, Kr, Xe ion beams with 2.5 MeV/nucleon fixed energy. The cyclotron is equipped with system of axial injection and ECR ion source DECRIS-5, operating at the frequency of 18 GHz. This article reviews the design and construction of DECRIS-5 ion source along with some initial commissioning results. PMID:24593512

Efremov, A; Bogomolov, S; Lebedev, A; Loginov, V; Yazvitsky, N

2014-02-01

133

Laser separation of medical isotopes  

Microsoft Academic Search

There is an increasing demand for different separated isotopes as feed material for reactor and cyclotron-produced radioisotopes used by a fast-growing radiopharmaceutical industry. One new technology that may meet future demands for medical isotopes is molecular laser isotope separation (MLIS). This method was investigated for the enrichment of uranium in the 1970`s and 1980s by Los Alamos National Laboratory, Isotope

J. W. Eerkens; D. A. Puglishi; W. H. Miller

1996-01-01

134

Radioisotope production at the Kazakhstan cyclotron  

Microsoft Academic Search

Cyclotrons play an important role for production of carrier-free radioisotopes for various applications in the nuclear medicine, industry, ecology and science. Kazakhstan variable energy isochronous cyclotron, K = 50 MeV, is a 150 cm compact-pole 3 sector positive ion machine. It generates different beams of light ions: protons 6-30 MeV, deuterons 12.5-25 MeV, 3He-ions 18.5-62 MeV, alpha-particles 25-50 MeV. In

A. Arzumanov; V. Batischev; N. Berdinova; A. Borissenko; G. Chumikov; N. Gorodisskaya; A. Knyazev; V. Koptev; S. Lyssukhin; Yu. Popov; G. Sychikov; D. Zheltov

2003-01-01

135

Design and testing of an electron cyclotron resonance heating ion source for use in high field compact superconducting cyclotrons  

E-print Network

The main goal of this project is to evaluate the feasibility of axial injection of a high brightness beam from an Electron Cyclotron Resonance ion source into a high magnetic field cyclotron. Axial injection from an ion ...

Artz, Mark E

2012-01-01

136

Transmission characteristics of cyclotron harmonic waves in plasma  

Microsoft Academic Search

In recent years the importance of cyclotron harmonic waves has become apparent in many branches of plasma physics. For example, it has been demonstrated that they are involved in the anomalously high noise radiation near the electron cyclotron harmonic frequencies that has been observed from thermonuclear fusion study devices, and that they can explain the cyclotron harmonic resonances observed in

F. W. Crawford; H. H. Weiss

1966-01-01

137

Cyclotron-based neutron source for BNCT  

SciTech Connect

Kyoto University Research Reactor Institute (KURRI) and Sumitomo Heavy Industries, Ltd. (SHI) have developed a cyclotron-based neutron source for Boron Neutron Capture Therapy (BNCT). It was installed at KURRI in Osaka prefecture. The neutron source consists of a proton cyclotron named HM-30, a beam transport system and an irradiation and treatment system. In the cyclotron, H- ions are accelerated and extracted as 30 MeV proton beams of 1 mA. The proton beams is transported to the neutron production target made by a beryllium plate. Emitted neutrons are moderated by lead, iron, aluminum and calcium fluoride. The aperture diameter of neutron collimator is in the range from 100 mm to 250 mm. The peak neutron flux in the water phantom is 1.8 Multiplication-Sign 109 neutrons/cm{sup 2}/sec at 20 mm from the surface at 1 mA proton beam. The neutron source have been stably operated for 3 years with 30 kW proton beam. Various pre-clinical tests including animal tests have been done by using the cyclotron-based neutron source with {sup 10}B-p-Borono-phenylalanine. Clinical trials of malignant brain tumors will be started in this year.

Mitsumoto, T.; Yajima, S.; Tsutsui, H.; Ogasawara, T.; Fujita, K. [Sumitomo Heavy Industries, Ltd (Japan); Tanaka, H.; Sakurai, Y.; Maruhashi, A. [Kyoto University Research Reactor Institute (Japan)

2013-04-19

138

Ion cyclotron resonance heating on TEXTOR  

Microsoft Academic Search

Ion cyclotron heating on TEXTOR has now reached the Megajoule level. The heating scenario is normally mode conversion but occasionally minority heating in a D-(H) plasma. With appropriate wall conditioning by carbonization more than 1 MW of RF power has been injected for long pulse durations ( approximately 1 s). The ICRF heated plasma is characterized by a quasi-stationarity of

A. M. Messiaen; V. P. Bhatnagar; T. Delvigne; P. Descamps; F. Durodie; M. Jadoul; R. Koch; D. Lebeau; D. I. C. Pearson; P. E. Vandenplas; A. Vanderstraeten; R. Van Nieuwenhove; G. Van Oost; G. Van Wassenhove; R. R. Weynants; H. L. Bay; G. Bertschinger; W. Bieger; P. Bogen; G. A. Campbell; R. W. Conn; K. H. Dippel; H. G. Esser; K. H. Finken; G. Fuchs; B. Giesen; D. M. Goebel; R. Graffmann; S. E. Guthrie; H. Hartwig; E. Hintz; G. Hrehuss; F. Hoenen; K. Hoethker; A. Kaleck; L. Konen; M. Korten; Y. T. Lie; K. Liung; M. Lochter; A. E. Pontau; A. Pospieszczyk; D. Rusbuldt; U. Samm; B. Schweer; J. Schluter; H. Soltwisch; G. Thomas; F. Waelbroeck; G. Waidmann; P. Wienhold; J. Winter; G. H. Wolf

1986-01-01

139

Cyclotron-based neutron source for BNCT  

NASA Astrophysics Data System (ADS)

Kyoto University Research Reactor Institute (KURRI) and Sumitomo Heavy Industries, Ltd. (SHI) have developed a cyclotron-based neutron source for Boron Neutron Capture Therapy (BNCT). It was installed at KURRI in Osaka prefecture. The neutron source consists of a proton cyclotron named HM-30, a beam transport system and an irradiation & treatment system. In the cyclotron, H- ions are accelerated and extracted as 30 MeV proton beams of 1 mA. The proton beams is transported to the neutron production target made by a beryllium plate. Emitted neutrons are moderated by lead, iron, aluminum and calcium fluoride. The aperture diameter of neutron collimator is in the range from 100 mm to 250 mm. The peak neutron flux in the water phantom is 1.8×109 neutrons/cm2/sec at 20 mm from the surface at 1 mA proton beam. The neutron source have been stably operated for 3 years with 30 kW proton beam. Various pre-clinical tests including animal tests have been done by using the cyclotron-based neutron source with 10B-p-Borono-phenylalanine. Clinical trials of malignant brain tumors will be started in this year.

Mitsumoto, T.; Yajima, S.; Tsutsui, H.; Ogasawara, T.; Fujita, K.; Tanaka, H.; Sakurai, Y.; Maruhashi, A.

2013-04-01

140

On Resonant Heating Below the Cyclotron Frequency  

SciTech Connect

Resonant heating of particles by an electrostatic wave propagating perpendicular to a confining uniform magnetic field is examined. It is shown that, with a sufficiently large wave amplitude, significant perpendicular stochastic heating can be obtained with wave frequency at a fraction of the cyclotron frequency.

Liu Chen; Zhihong Lin; White, R.

2001-02-02

141

Beamline developments in commercial cyclotron facilities  

NASA Astrophysics Data System (ADS)

In recent years SPECT radioisotope producers have generally built their businesses around 30 MeV cyclotrons. An important aspect of these production facilities is the beamline system which must have a high transmission rate, low residual radiation, and low maintenance requirements. This paper describes developments in these areas.

Dehnel, M. P.; Trudel, A.; Duh, T. S.; Stewart, T.

2005-12-01

142

Stereotactic Body Radiotherapy Versus Surgery for Medically Operable Stage I Non-Small-Cell Lung Cancer: A Markov Model-Based Decision Analysis  

SciTech Connect

Purpose: To compare the quality-adjusted life expectancy and overall survival in patients with Stage I non-small-cell lung cancer (NSCLC) treated with either stereotactic body radiation therapy (SBRT) or surgery. Methods and Materials: We constructed a Markov model to describe health states after either SBRT or lobectomy for Stage I NSCLC for a 5-year time frame. We report various treatment strategy survival outcomes stratified by age, sex, and pack-year history of smoking, and compared these with an external outcome prediction tool (Adjuvant{exclamation_point} Online). Results: Overall survival, cancer-specific survival, and other causes of death as predicted by our model correlated closely with those predicted by the external prediction tool. Overall survival at 5 years as predicted by baseline analysis of our model is in favor of surgery, with a benefit ranging from 2.2% to 3.0% for all cohorts. Mean quality-adjusted life expectancy ranged from 3.28 to 3.78 years after surgery and from 3.35 to 3.87 years for SBRT. The utility threshold for preferring SBRT over surgery was 0.90. Outcomes were sensitive to quality of life, the proportion of local and regional recurrences treated with standard vs. palliative treatments, and the surgery- and SBRT-related mortalities. Conclusions: The role of SBRT in the medically operable patient is yet to be defined. Our model indicates that SBRT may offer comparable overall survival and quality-adjusted life expectancy as compared with surgical resection. Well-powered prospective studies comparing surgery vs. SBRT in early-stage lung cancer are warranted to further investigate the relative survival, quality of life, and cost characteristics of both treatment paradigms.

Louie, Alexander V. [Department of Oncology, University of Western Ontario, London, ON (Canada); Rodrigues, George, E-mail: george.rodrigues@lhsc.on.ca [Department of Oncology, University of Western Ontario, London, ON (Canada); Department of Epidemiology/Biostatistics, University of Western Ontario, London, ON (Canada); Hannouf, Malek [Department of Epidemiology/Biostatistics, University of Western Ontario, London, ON (Canada); Zaric, Gregory S. [Department of Epidemiology/Biostatistics, University of Western Ontario, London, ON (Canada); Richard Ivey School of Business, University of Western Ontario, London, ON (Canada); Palma, David A. [Department of Oncology, University of Western Ontario, London, ON (Canada); Cao, Jeffrey Q. [Department of Oncology, University of Western Ontario, London, ON (Canada); Richard Ivey School of Business, University of Western Ontario, London, ON (Canada); Yaremko, Brian P. [Department of Oncology, University of Western Ontario, London, ON (Canada); Malthaner, Richard [Department of Epidemiology/Biostatistics, University of Western Ontario, London, ON (Canada); Division of Surgery, University of Western Ontario, London, ON (Canada); Mocanu, Joseph D. [Richard Ivey School of Business, University of Western Ontario, London, ON (Canada)

2011-11-15

143

High Radiation Dose May Reduce the Negative Effect of Large Gross Tumor Volume in Patients With Medically Inoperable Early-Stage Non-Small Cell Lung Cancer  

SciTech Connect

Purpose: To determine whether the effect of radiation dose varies with gross tumor volume (GTV) in patients with stage I/II non-small cell lung cancer (NSCLC). Methods and Materials: Included in the study were 114 consecutive patients with medically inoperable stage I/II NSCLC treated with three-dimensional conformal radiotherapy between 1992 and 2004. The median biologic equivalent dose (BED) was 79.2 Gy (range, 58.2-124.5 Gy). The median GTV was 51.8 cm{sup 3} (range, 2.1-727.8 cm{sup 3}). The primary endpoint was overall survival (OS). Kaplan-Meier estimation and Cox regression models were used for survival analyses. Results: Multivariate analysis showed that there was a significant interaction between radiation dose and GTV (p < 0.001). In patients with BED {<=}79.2 Gy (n = 68), the OS medians for patients with GTV >51.8 cm{sup 3} and {<=}51.8 cm{sup 3} were 18.2 and 23.9 months, respectively (p 0.015). If BED was >79.2 Gy (n = 46), no significant difference was found between GTV groups (p = 0.681). For patients with GTV >51.8 cm{sup 3} (n = 45), the OS medians in those with BED >79.2 Gy and {<=}79.2 Gy were 30.4 and 18.2 months, respectively (p < 0.001). If GTV was {<=}51.8 cm{sup 3} (n = 45), the difference was no longer significant (p = 0.577). Conclusion: High-dose radiation is more important for patients with larger tumors and may be effective in reducing the adverse outcome associated with large GTV. Further prospective studies are needed to confirm this finding.

Zhao Lujun [Department of Radiation Oncology, University of Michigan Medical Center, Ann Arbor, MI (United States); West, Brady T. [Center for Statistical Consultation and Research, University of Michigan Medical Center, Ann Arbor, MI (United States); Hayman, James A. [Department of Radiation Oncology, University of Michigan Medical Center, Ann Arbor, MI (United States); Lyons, Susan [Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, MI (United States); Department of Radiation Oncology, Veterans Administration Health Center, Ann Arbor, MI (United States); Cease, Kemp [Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, MI (United States); Department of Radiation Oncology, Veterans Administration Health Center, Ann Arbor, MI (United States); Kong, F.-M. [Department of Radiation Oncology, University of Michigan Medical Center, Ann Arbor, MI (United States) and Department of Radiation Oncology, Veterans Administration Health Center, Ann Arbor, MI (United States)]. E-mail: Fengkong@med.umich.edu

2007-05-01

144

Ion cyclotron heating experiments in EBT-S  

SciTech Connect

Fast-wave heating and propagation experiments in the ion cyclotron range of frequencies (ICRF) have been carried out on EBT-S under steady-state conditions at power levels up to 20 kW and under pulsed conditions at power levels up to 100 kW. The waves were launched using a single Faraday-shielded loop antenna installed on the midplane of one of the 24 cavity sectors. Substantial ion heating was observed at frequencies above the second harmonic for hydrogen plasmas and at frequencies above the third harmonic for deuterium plasmas, corresponding with the onset of wave propagation around the torus. The heating under these conditions is anomalous. In the case of deuterium plasmas, a small residual concentration (2 to 5%) of hydrogen was heated, but this component did not appear to affect the deuterium heating.

Baity, F.W.; Davis, W.A.; Eldridge, O.C.; Glowienka, J.C.; Hillis, D.L.; Rasmussen, D.A.; Richards, R.K.; Mullen, J.H.; Owens, T.L.

1982-01-01

145

Production of flickering aurora and field-aligned electron flux by electromagnetic ion cyclotron waves  

NASA Technical Reports Server (NTRS)

Recent observations have suggested that flickering aurora is produced by a modulation of the field-aligned component of the electron flux within an auroral arc. It is proposed that a portion of the field-aligned electrons are of ionospheric origin and that these electrons are accelerated and their flux modulated by electromagnetic ion cyclotron waves that occur below the main acceleration region on auroral arc field lines. A model of the electromagnetic ion cyclotron wave shows that the parallel phase velocity of the wave increase as the wave propagates toward the ionosphere. A test particle calculation shows that ionospheric electrons trapped or reflected by the wave are accelerated to energies of several keV and that their flux is modulated at the wave frequency. The relative amplitudes of the model wave electric fields are consistent with the observations of small-scale low-frequency ionospheric and magnetospheric electric fields near auroral arcs of approximately 10 mV/m and 100 mV/m, respectively. The large-amplitude ion cyclotron waves also produce a ponderomotive force and a self-consistent ambipolar electric field. Energy considerations show that the downward energy flux in the electromagnetic ion cyclotron wave can be several percent of the total downward auroral electron energy flux.

Temerin, M.; Mcfadden, J.; Boehm, M.; Carlson, C. W.; Lotko, W.

1986-01-01

146

Phase-resolved cyclotron spectroscopy of polars  

NASA Astrophysics Data System (ADS)

In this thesis we use phase-resolved cyclotron spectroscopy to study polars. Polars are a subset of cataclysmic variables where the primary WD is highly magnetic. In this case, the accretion flow is constrained along the magnetic field lines and eventually deposited on the WD, where the accreting material interacts with the atmosphere, forming a standing hydrodynamic shock at a location termed the accretion region, and emitting cyclotron radiation. Due to its field strength, cyclotron radiation from polars falls at either UV, optical or NIR wavelengths. While a substantial amount of optical cyclotron spectra have been published on polars, the NIR remains relatively unstudied. In this thesis, we present NIR spectroscopy for fifteen polars. Additionally, while a single cyclotron spectrum is needed to constrain the shock parameters, phase- resolved spectroscopy allows for a more in-depth analysis of the shock structure and the geometry of the accretion region. Of the fifteen polars observed, eight yielded spectra of adequate quality to be modeled in this manner: EF Eri, EQ Cet, AN UMa, VV Pup, AM Her, ST LMi, MR Ser, and MQ Dra. Initially, we used the industry standard "Constant Lambda (CL)" code to model each object. The code is fast, but produces only globally averaged values of the salient shock parameters: B - the magnetic field strength, kT - the plasma temperature, logL - the "size parameter" of the accretion column, and TH- the viewing angle between the observer and the magnetic field. For each object we present CL models for our NIR phase-resolved cyclotron spectra. Subsequently, we use a more advanced "Structured-Shock" code built by Fischer & Beuermann (2001)("F&B") to remodel three objects: EQ Cet, MQ Dra, and EF Eri. The F&B code allows for input of more physical parameters and most importantly does ray tracing through a simulated one-dimensional accretion column. To determine the outgoing spectrum, temperature and velocity profiles are needed to reconstruct the characteristics of the plasma at each location. A substantial effort was made to accurately construct these profiles. Finally, we compare the results of the CL and F&B codes to determine when the extra complexity and significantly longer computational times of F&B modeling are necessary to understand these systems.

Campbell, Ryan

147

Plasma processing of spent nuclear fuel by two-frequency ion cyclotron resonance heating  

Microsoft Academic Search

A previously developed method for analyzing the plasma processing of spent nuclear fuel is generalized to a plasma containing\\u000a multicharged fuel ions. In such a plasma, ion cyclotron resonance heating of nuclear ash ions should be carried out in two\\u000a monochromatic RF fields of different frequencies, provided that the fraction of ? multicharged ions is small, ? ? 0.1, a

A. V. Timofeev

2009-01-01

148

Experimental study of an ion cyclotron resonance accelerator  

NASA Astrophysics Data System (ADS)

The Ion Cyclotron Resonance Accelerator (ICRA) uses the operating principles of cyclotrons and gyrotrons. The novel geometry of the ICRA allows an ion beam to drift axially while being accelerated in the azimuthal direction. Previous work on electron cyclotron resonance acceleration used waveguide modes to accelerate an electron beam [5]. This research extends cyclotron resonance acceleration to ions by using a high field superconducting magnet and an rf driven magnetron operating at a harmonic of the cyclotron frequency. The superconducting solenoid provides an axial magnetic field for radial confinement and an rf driven magnetron provides azimuthal electric fields for acceleration. The intent of the ICRA concept is to create an ion accelerator which is simple, compact, lightweight, and inexpensive. Furthermore, injection and extraction are inherently simple since the beam drifts through the acceleration region. However, use of this convenient geometry leads to an accelerated beam with a large energy spread. Therefore, the ICRA will be most useful for applications which do not require a monoenergetic beam. An ICRA designed to accelerate protons to 10 MeV would be useful for the production of radioisotopes, or neutron beams, as well as for materials science applications. As a first step toward producing an ICRA at useful energies, a low energy ICRA has been designed, built, and tested as a demonstration of the concept. Analytical theory and a full computer model have been developed for the ICRA. Beam measurements taken on the ICRA experiment have been compared with theory. The ICRA computer model uses realistic fields of the solenoid, magnetron, and electrostatic bend. This code tracks single particle trajectories from the ion source through the entire system to a target face. A full emittance injected beam can be modeled by tracking many single particle trajectories. The ICRA experiment is designed to accelerate a proton beam from 5 keV to 50 keV in 5 turns. A superconducting solenoid provides a 2.5 Tesla axial magnetic field. The accelerating structure built for the experiment operates at 152 MHz (4th harmonic) and provides 3 kV across 8 gaps. Measurements of the accelerated beam current vs. beam orbit radius indicate an energy distribution ranging from near zero to near the full design energy, with 7% of the beam current above 24 keV and 1% above 42 keV. Energy distributions generated using the ICRA computer model show reasonable agreement with the experimental data. After a small correction of the bend voltage, the computer model shows good agreement with the magnitude and shape of the experimental data for a wide range of turn number. Finally, a scheme for optimization of the basic ICRA design is given. Design parameters are identified which minimize cost and which maximize the accelerated beam current. Three 10 MeV proton designs are given which offer a compromise between low cost and a high quality beam.

Ramsell, Christopher T.

2000-11-01

149

Phase-resolved Cyclotron Spectroscopy of Polars  

NASA Astrophysics Data System (ADS)

We present phase-resloved( 0.1 phase intervals) cyclotron spectrocopy of five polars(AN UMa, EF Eri, VV Pup, and EQ Cet, and MQ Dra) obtained with SPEX on the IRTF as well as Apache Point Observatory. SPEX covers the I, J, H, and K bands simultaneously allowing for great wavelength coverage of all the observed systems. For each object, a Constant Lambda (CL) code was run to compute model cyclotron spectra which were fit to the data observed by altering four parameters: B, the magnetic field strength, T, the global temperature of the plasma in the accretion region, Lambda, the "size parameter" of the accretion column, and Theta, the viewing angle. To allow for more physical setup in the accretion regions in question, we will soon transition to a structured-shock code based on Fischer and Beuermann (2001), which allows the effects of variable mass accretion and magnetic fields to be included.

Campbell, Ryan; Harrison, T. E.

2007-12-01

150

Microhardness evaluation of cyclotron foil windows  

NASA Astrophysics Data System (ADS)

The production of radiopharmaceuticals for application to positron emission tomography necessitates radionuclides of finite specific activity and chemical purity. Reliable, routine production of the short-lived, biologically useful radionuclides has required careful selection of target system materials. The degenerative effects of high beam currents and use of refrigerated cooling units on metallic cyclotron target windows are of particular interest. Repeated subjection of the metallic windows and target bodies to energetic charged particles induces crystalline lattice imperfections and strain hardening. The reduction in ductility of the foil window appears to correlate with an increase in hardness as evaluated using the Knoop microhardness technique and optical microscopic examination on both aluminum and Havar irradiated cyclotron windows. A summary of our results on the above effects will be presented.

Finn, R.; Shives, T.; Brady, C.; Plascjak, P.; Meyer, W.; Sheh, Y.

1989-04-01

151

CURRENTS DRIVE BY ELECTRON CYCLOTRON WAVES  

E-print Network

LABORATORY P R I N C E T O N U N I V E R S I T Y P R I N C E T O N , N E W 'JERSEY This work was supported bv. Link: http://charles.karney.info/biblio/karney81d.html #12;Currents Driven by Electron Cyclotron Waves Charles F. F. Karney and Nathaniel J. Fisch Plasma Physics Iaboratory, Princeton University Princeton, New

Karney, Charles

152

Ion cyclotron resonance heating system on Aditya  

Microsoft Academic Search

An ion cyclotron resonance heating (ICRH) system has been designed, fabricated indigenously and commissioned on Tokamak Aditya.\\u000a The system has been commissioned to operate between 20.0 and 47.0 MHz at a maximum power of 200 kW continuous wave (CW). Duration\\u000a of 500 ms is sufficient for operation on Aditya, however, the same system feeds the final stage of the 1.5

D. Bora; Sunil Kumar; Raj Singh; S. V. Kulkarni; A. Mukherjee; J. P. Singh; Raguraj Singh; S. Dani; A. Patel; Sai Kumar; V. George; Y. S. S. Srinivas; P. Khilar; M. Kushwah; P. Shah; H. M. Jadav; Rajnish Kumar; S. Gangopadhyay; H. Machhar; B. Kadia; K. Parmar; A. Bhardwaj; Suresh Adav; D. Rathi; D. S. Bhattacharya

2005-01-01

153

Coronal ion-cyclotron beam instabilities within the multi-fluid description  

E-print Network

Spectroscopic observations and theoretical models suggest resonant wave-particle interactions, involving high-frequency ion-cyclotron waves, as the principal mechanism for heating and accelerating ions in the open coronal holes. However, the mechanism responsible for the generation of the ion-cyclotron waves remains unclear. One possible scenario is that ion beams originating from small-scale reconnection events can drive micro-instabilities that constitute a possible source for the excitation of ion-cyclotron waves. In order to study ion beam-driven electromagnetic instabilities, the multi-fluid model in the low-beta coronal plasma is used. While neglecting the electron inertia this model allows one to take into account ion-cyclotron wave effects that are absent from the one-fluid MHD model. Realistic models of density and temperature as well as a 2-D analytical magnetic field model are used to define the background plasma in the open-field funnel region of a polar coronal hole. Considering the WKB approximation, a Fourier plane-wave linear mode analysis is employed in order to derive the dispersion relation. Ray-tracing theory is used to compute the ray path of the unstable wave as well as the evolution of the growth rate of the wave while propagating in the coronal funnel. We demonstrate that, in typical coronal holes conditions and assuming realistic values of the beam velocity, the free energy provided by the ion beam propagating parallel the ambient field can drive micro-instabilities through resonant ion-cyclotron excitation.

R. Mecheri; E. Marsch

2007-06-06

154

Whistler and Alfvén Mode Cyclotron Masers in Space  

NASA Astrophysics Data System (ADS)

Preface; 1. Introduction; 2. Basic theory of cyclotron masers (CMs); 3. Linear theory of the cyclotron instability (CI); 4. Backward wave oscillator (BWO) regime in CMs; 5. Nonlinear cyclotron wave-particle interactions for a quasi-monochromatic wave; 6. Nonlinear interaction of quasi-monochromatic whistler mode waves with gyroresonant electrons in an in homogeneous plasma; 7. Wavelet amplification in an inhomogeneous plasma; 8. Quasi-linear theory of cyclotron masers; 9. Nonstationary generation regimes, and modulation effects; 10. ELF/VLF noise-like emissions and electrons in the Earth's radiation belts; 11. Generation of discrete ELF/VLF whistler mode emissions; 12. Cyclotron instability of the proton radiation belts; 13. Cyclotron masers elsewhere in the solar system and in laboratory plasma devices; Epilogue; Glossary of terms; List of acronyms; References; Index.

Trakhtengerts, V. Y.; Rycroft, M. J.

2008-11-01

155

Whistler and Alfvén Mode Cyclotron Masers in Space  

NASA Astrophysics Data System (ADS)

Preface; 1. Introduction; 2. Basic theory of cyclotron masers (CMs); 3. Linear theory of the cyclotron instability (CI); 4. Backward wave oscillator (BWO) regime in CMs; 5. Nonlinear cyclotron wave-particle interactions for a quasi-monochromatic wave; 6. Nonlinear interaction of quasi-monochromatic whistler mode waves with gyroresonant electrons in an in homogeneous plasma; 7. Wavelet amplification in an inhomogeneous plasma; 8. Quasi-linear theory of cyclotron masers; 9. Nonstationary generation regimes, and modulation effects; 10. ELF/VLF noise-like emissions and electrons in the Earth's radiation belts; 11. Generation of discrete ELF/VLF whistler mode emissions; 12. Cyclotron instability of the proton radiation belts; 13. Cyclotron masers elsewhere in the solar system and in laboratory plasma devices; Epilogue; Glossary of terms; List of acronyms; References; Index.

Trakhtengerts, V. Y.; Rycroft, M. J.

2012-10-01

156

Ionospheric Modification at Twice the Electron Cyclotron Frequency  

NASA Astrophysics Data System (ADS)

In 2004, a new transmission band was added to the HAARP high-frequency ionospheric modification facility that encompasses the second electron cyclotron harmonic at altitudes between ˜220 and 330 km. Initial observations indicate that greatly enhanced airglow occurs whenever the transmission frequency approximately matches the second electron cyclotron harmonic at the height of the upper hybrid resonance. This is the reverse of what happens at higher electron cyclotron harmonics. The measured optical emissions confirm the presence of accelerated electrons in the plasma.

Djuth, F. T.; Pedersen, T. R.; Gerken, E. A.; Bernhardt, P. A.; Selcher, C. A.; Bristow, W. A.; Kosch, M. J.

2005-03-01

157

Current driven electrostatic and electromagnetic ion cyclotron instabilities  

NASA Technical Reports Server (NTRS)

Growth rates and parameter dependences are calculated for the current driven instabilities of electrostatic (with finite-beta corrections) and electromagnetic ion cyclotron waves. For 0.25 (T sub e)/(T sub i) 2.5, ion cyclotron waves have large growth rates, while ion acoustic waves are still stable. In fusion devices, where electrostatic waves may be stable, electromagnetic ion cyclotron waves are unstable for beta sub i 0.001.

Forslund, D. W.; Kennel, C. F.; Kindel, J. M.

1971-01-01

158

C235-V3 cyclotron for a proton therapy center to be installed in the hospital complex of radiation medicine (Dimitrovgrad)  

NASA Astrophysics Data System (ADS)

Proton therapy is an effective method of treating oncologic diseases. In Russia, construction of several centers for proton and ion therapy is slated for the years to come. A proton therapy center in Dimitrovgrad will be the first. The Joint Institute for Nuclear Research (Russia) in collaboration with Ion Beam Application (IBA) (Belgium) has designed an C235-V3 medical proton cyclotron for this center. It outperforms previous versions of commercial IBA cyclotrons, which have already been installed in 11 oncologic hospital centers in different countries. Experimental and calculation data for the beam dynamics in the C235-V3 medical cyclotron are presented. Reasons for beam losses during acceleration are considered, the influence of the magnetic field radial component in the midplane of the accelerator and main resonances is studied, and a beam extraction system is designed. In 2011-2012 in Dubna, the cyclotron was mounted, its magnetic field was properly configured, acceleration conditions were optimized, and beam extraction tests were carried out after which it was supplied to Dimitrovgrad. In the C235-V3 cyclotron, an acceleration efficiency of 72% and an extraction efficiency of 62% have been achieved without diaphragming to form a vertical profile of the beam.

Galkin, R. V.; Gurskii, S. V.; Jongen, Y.; Karamysheva, G. A.; Kazarinov, M. Yu.; Korovkin, S. A.; Kostromin, S. A.; Calderan, J.-M.; Cahay, P.; Mokrenko, S. P.; Morozov, N. A.; Nkongolo, H.; Ol'shevskii, A. G.; Paradis, Y.; Petrov, D. S.; Romanov, V. M.; Samsonov, E. V.; Syresin, E. M.; Shakun, A. N.; Shakun, N. G.; Shirkov, G. D.; Shirkov, S. G.

2014-06-01

159

The surface-state of the topological insulator Bi2Se3 revealed by cyclotron resonance  

SciTech Connect

Transport measurements of topological insulators are dominated by the conductivity of the bulk, leading to substantial difficulties in resolving the properties of the surface. To this end, we use high magnetic field, rf- and microwave-spectroscopy to selectively couple to the surface conductivity of Bi2Se3 at high frequency. In the frequency range of a few GHz we observe a crossover from quantum oscillations indicative of a small 3D Fermi surface, to cyclotron resonance indicative of a 2D surface state. By probing the conductivity at reduced skin depths, we have observed a 2D cyclotron resonance from a material whose bulk Fermi-surface is 3D. The frequency-magnetic field scaling of this resonance is inconsistent with the bulk effective mass, but more consistent with the dispersion and band filling of a Dirac-like surface state as observed by ARPES, with substantial manybody renormalization.

Mcdonald, Ross D [Los Alamos National Laboratory; Ayala - Valenzuela, Oscar E [Los Alamos National Laboratory; Altarawneh, Moaz M [Los Alamos National Laboratory; Analytis, James G [STANFORD UNIV/SLAC; Chu, J. H. [STANFORD UNIV/SLAC; Fisher, R. [STANFORD UNIV/SLAC

2011-01-14

160

The Effect of Vacuum Polarization and Proton Cyclotron Resonances on Photon Propagation in Strongly Magnetized Plasmas  

NASA Astrophysics Data System (ADS)

We consider the effects of vacuum polarization and proton cyclotron resonances on the propagation of radiation through a strongly magnetized plasma. We analyze the conditions under which the photons evolve adiabatically through the resonant density and find that the adibaticity condition is satisfied for most photon energies of interest, allowing for a normal-mode treatment of the photon propagation. We then construct radiative equilibrium atmosphere models of strongly magnetized neutron stars that includes these effects, employing a new numerical method that resolves accurately the sharp changes of the absorption and mode-coupling cross sections at the resonant densities. We show that the resulting spectra are modified by both resonances and are harder at all field strengths than a blackbody at the effective temperature. We also show that the narrow absorption features introduced by the proton cyclotron resonance have small equivalent widths. We discuss the implications of our results for properties of thermal emission from the surfaces of young neutron stars.

Özel, Feryal

2003-01-01

161

HISTORY of the UMH Medical Library The medical library of Cedars Medical Center was initially housed in a remove and relatively  

E-print Network

and Journals for the Small Medical Library. Requests from medical staff members were incorporated and journals were/are based on Brandon's List of Books and Journals for the Small Medical LibraryHISTORY of the UMH Medical Library 1 The medical library of Cedars Medical Center was initially

Miami, University of

162

Medication Errors  

MedlinePLUS

... Coordinating Council for Medication Error Reporting and Prevention Medication Errors Within the Center for Drug Evaluation and ... broader product safety issues. Drug Products Associated with Medication Errors FDA Drug Safety Communication: Serious medication errors ...

163

A real-time beam-profile monitor for a PET cyclotron  

SciTech Connect

Beam profiles in medical cyclotrons are traditionally measured using techniques that do not provide any information about short-term fluctuations of the beam shape or beam intensity. To overcome this, we have developed a real-time harp beam profile monitor which can withstand beam power in excess of 300 W. The monitor and electronics were constructed and applied toward a 13 MeV proton beam with current of up to 25 {mu}A. Herein are reported preliminary beam-profile measurement results.

Hoehr, C.; Uittenbosch, T.; Verzilov, V.; English, W.; Buckley, K.; Gray, D.; Kellog, S.; Cameron, D.; Schaffer, P. [TRIUMF, 4004 Wesbrook Mall, V6T 2A3 Vancouver (Canada)

2012-12-19

164

A real-time beam-profile monitor for a PET cyclotron  

NASA Astrophysics Data System (ADS)

Beam profiles in medical cyclotrons are traditionally measured using techniques that do not provide any information about short-term fluctuations of the beam shape or beam intensity. To overcome this, we have developed a real-time harp beam profile monitor which can withstand beam power in excess of 300 W. The monitor and electronics were constructed and applied toward a 13 MeV proton beam with current of up to 25 ?A. Herein are reported preliminary beam-profile measurement results.

Hoehr, C.; Uittenbosch, T.; Verzilov, V.; English, W.; Buckley, K.; Gray, D.; Kellog, S.; Cameron, D.; Schaffer, P.

2012-12-01

165

Electron cyclotron emission imaging in tokamak plasmas  

SciTech Connect

We discuss the recent history and latest developments of the electron cyclotron emission imaging diagnostic technique, wherein electron temperature is measured in magnetically confined plasmas with two-dimensional spatial resolution. The key enabling technologies for this technique are the large-aperture optical systems and the linear detector arrays sensitive to millimeter-wavelength radiation. We present the status and recent progress on existing instruments as well as new systems under development for future experiments. We also discuss data analysis techniques relevant to plasma imaging diagnostics and present recent temperature fluctuation results from the tokamak experiment for technology oriented research (TEXTOR).

Munsat, Tobin; Domier, Calvin W.; Kong, Xiangyu; Liang, Tianran; Luhmann, Jr.; Neville C.; Tobias, Benjamin J.; Lee, Woochang; Park, Hyeon K.; Yun, Gunsu; Classen, Ivo. G. J.; Donne, Anthony J. H.

2010-07-01

166

Impurity cyclotron resonance of anomalous Dirac electrons in graphene  

NASA Astrophysics Data System (ADS)

We have investigated a new feature of impurity cyclotron resonances common to various localized potentials of graphene. A localized potential can interact with a magnetic field in an unexpected way in graphene. It can lead to formation of anomalous boundstates that have a sharp peak with a width R in the probability density inside the potential and a broad peak of size magnetic length ? outside the potential. We investigate optical matrix elements of anomalous states and find that they are unusually small and depend sensitively on the magnetic field. The effect of many-body interactions on their optical conductivity is investigated using a self-consistent time-dependent Hartree-Fock approach. For a completely filled Landau level we find that an excited electron-hole pair, originating from the optical transition between two anomalous impurity states, is nearly uncorrelated with other electron-hole pairs, although it displays substantial exchange self-energy effects. This absence of correlation is a consequence of a small vertex correction in comparison to the difference between renormalized transition energies computed within the one electron-hole pair approximation. However, an excited electron-hole pair originating from the optical transition between a normal and an anomalous impurity state can be substantially correlated with other electron-hole states with a significant optical strength.

Kim, S. C.; Yang, S.-R. Eric; MacDonald, A. H.

2014-08-01

167

US Particle Accelerator School Cyclotrons: Old but Still New  

E-print Network

US Particle Accelerator School Cyclotrons: Old but Still New The history of accelerators is a history of inventions William A. Barletta Director, US Particle Accelerator School Dept. of Physics, MIT Economics Faculty, University of Ljubljana #12;US Particle Accelerator School ~ 650 cyclotrons operating

Dai, Pengcheng

168

The TRIUMF 500 MeV cyclotron: the driver accelerator  

NASA Astrophysics Data System (ADS)

ISAC's radioactive ion beams are currently produced in nuclear spallation reactions driven by an intense 480-MeV proton beam from the TRIUMF sector-focused cyclotron. In this article we describe the design and operation of the cyclotron, and also the extensive program of upgrading the equipment and beams that has enhanced its performance and reliability over recent years.

Bylinskii, I.; Craddock, M. K.

2014-01-01

169

Beam diagnostic systems in the IUCF Cooler and Cyclotron  

Microsoft Academic Search

Beam diagnostics for the Indiana University Cyclotron Facility (IUCF) Cooler synchrotron which have been recently developed include a beam phase feedback system to damp synchrotron oscillations induced by the RF system and a transverse phase space tracking system to measure the betatron fractional tunes and to investigate nonlinear beam dynamics. New cyclotron diagnostic systems include a new beam timing system

M. S. Ball; T. J. P. Ellison; B. J. Hamilton

1991-01-01

170

A Eight-Tesla Superconducting Magnet for Cyclotron Studies  

Microsoft Academic Search

Superconducting magnets have become broadly used for cyclotrons due to advantages of compactness and lower operation costs compared to conventional magnets. To gain benefits of higher magnetic fields beyond the 5 tesla cyclotron magnets which are under operation in several laboratories including the MSU\\/NSCL, a test magnet which can produce fields higher than 8 tesla was constructed. Our goal was

Jong-Won Kim

1994-01-01

171

Medical Practice Makes Perfect  

NASA Technical Reports Server (NTRS)

Cedaron Medical Inc., was founded in 1990 as a result of a NASA SBIR (Small Business Innovative Research) grant from Johnson Space Center to develop a Hand Testing and Exercise Unit for use in space. From that research came Dexter, a comprehensive workstation that creates a paperless environment for medical data management.

1998-01-01

172

Concept and utilization of a regional cyclotron center  

NASA Astrophysics Data System (ADS)

Cyclotrons have been proven to be valuable tools associated with development and applications of radioisotopes, radiochemicals and radiopharmaceuticals. Utilization of cyclotrons in biomedical research has increased to cover applications with SPECT and PET as major imaging modalities. The extensive cost of establishing a cyclotron facility has prompted development of more economically feasible sources of radioisotopes such as radioisotope generators. This idea presents the disadvantages of less versatility and production shortage. Therefore, the concept of a regional cyclotron center is being introduced for production of radiotracers to be utilized by users in the area. The Cyclotron Facility at the University of Texas Health Sciences Center at Houston (UTHSC-H) is being developed as a regional center where numerous radioisotopes and radiotracers have been developed and applied to various fields.

Emran, Ali M.

1993-06-01

173

Cyclotron Resonances in Electron Cloud Dynamics  

SciTech Connect

A new set of resonances for electron cloud dynamics in the presence of a magnetic field has been found. For short beam bunch lengths and low magnetic fields where lb<< 2pi c/omega c (with lb = bunch length, omega c = non-relativistic cyclotron frequency) resonances between the bunch frequency and harmonics of the electron cyclotron frequency cause an increase in the electron cloud density in narrow ranges of magnetic field near the resonances. For ILC parameters the increase in the density is up to a factor ~;;3, and the spatial distribution of the electrons is broader near resonances, lacking the well-defined vertical density"stripes" found for non-resonant cases. Simulations with the 2D computer code POSINST, as well as a single-particle tracking code, were used to elucidate the physics of the dynamics. The existence of the resonances has been confirmed in experiments at PEP-II. The resonances are expected to affect the electron cloud dynamics in the fringe fields of conventional lattice magnets and in wigglers, where the magnetic fields are low. Results of the simulations and experimental observations, the reason for the bunch-length dependence, and details of the dynamics are discussed here.

Celata, C. M.; Furman, Miguel A.; Vay, J.-L.; Ng, J. S.T.; Grote, D. P.; Pivi, M. T. F.; Wang, L. F.

2009-04-29

174

Cyclotron Resonances in Electron Cloud Dynamics  

SciTech Connect

A new set of resonances for electron cloud dynamics in the presence of a magnetic field has been found. For short beam bunch lengths and low magnetic fields where l{sub b} << 2{pi}{omega}{sub c}, (l{sub b} = bunch duration, {omega}{sub c} = non-relativistic cyclotron frequency) resonances between the bunch frequency and harmonics of the cyclotron frequency cause an increase in the electron cloud density in narrow ranges of magnetic field near the resonances. For ILC parameters the increase in the density is up to a factor {approx} 3, and the spatial distribution of the electrons is broader near resonances, lacking the well-defined density 'stripes' of multipactoring found for non-resonant cases. Simulations with the 2D computer code POSINST, as well as a single-particle tracking code, were used to elucidate the physics of the dynamics. The resonances are expected to affect the electron cloud dynamics in the fringe fields of conventional lattice magnets and in wigglers, where the magnetic fields are low. Results of the simulations, the reason for the bunch-length dependence, and details of the dynamics will be discussed.

Celata, C M; Furman, M A; Vay, J L; Grote, D P; Ng, J T; Pivi, M F; Wang, L F

2009-05-05

175

Ion Cyclotron Waves in the VASIMR  

NASA Astrophysics Data System (ADS)

The Variable Specific Impulse Magnetoplasma Rocket is an electric propulsion system under development at Ad Astra Rocket Company that utilizes several processes of ion acceleration and heating that occur in the Birkeland currents of an auroral arc system. Among these processes are parallel electric field acceleration, lower hybrid resonance heating, and ion cyclotron resonance heating. The VASIMR is capable of laboratory simulation of electromagnetic ion cyclotron wave heating during a single pass of the plasma through the resonance region. The plasma is generated by a helicon discharge of about 25 kW then passes through an RF booster stage that shoots left hand polarized slow mode waves from the high field side of the resonance. This paper will focus on the upgrades to the VX-200 test model over the last year. After summarizing the VX- 50 and VX-100 results, the new data from the VX-200 model will be presented. Lastly, the changes to the VASIMR experiment due to Ad Astra Rocket Company's new facility in Webster, Texas will also be discussed, including the possibility of collaborative experiments at the new facility.

Brukardt, M. S.; Bering, E. A.; Chang-Diaz, F. R.; Squire, J. P.; Longmier, B.

2008-12-01

176

Ion cyclotron bands in VLF saucers  

NASA Technical Reports Server (NTRS)

In the wideband VLF data obtained by the polar orbiting DE-1 satellite over the polar night ion trough region of the upper ionosphere, conspicuous frequency-band structures are found to occur both in absorption and emission, particularly associating with VLF saucers. The attenuation bands indicate that the ions of atomic hydrogen from the polar ionosphere are accelerated by the ac electric fields of VLF waves oscillating normal to the static magnetic field, analogous to a cyclotron accelerator. The observed frequencies of the cyclotron harmonics suggest that the acceleration is taking place in the layer below the satellite at a geocentric distance of less than about 1.5 earth radii. This example indicates the existence of upward propagating hiss at those altitudes inside the auroral zone. On the other hand, the frequency shifts of the emission bands are attributed to a combination of two different types of Doppler shift, one due to the orbital motion of the satellite and the other due to the upward motion of the medium at the emission source. This indicates the existence of an upward plasma flow at the source, with a velocity of the order of 20 km/s inside the saucer. The amount of this frequency shift decreases with increasing harmonic order, indicating a higher phase velocity for the electrostatic waves of higher harmonic order.

Maeda, Kaichi; Fung, Shing F.; Calvert, Wynne

1990-01-01

177

ICRH of JET and LHD Majority Ions at Their Fundamental Cyclotron Frequency  

NASA Astrophysics Data System (ADS)

Results of the experimental studies of ICRH at the fundamental cyclotron frequency of the majority deuterons in JET plasmas with near-tangential deuteron neutral beam injection (NBI) are presented. 1D, 2D and 3D ICRH modeling indicated that several ITER relevant mechanisms of heating may occur simultaneously in this heating scheme: fundamental ion cyclotron resonance heating of majority and beam D ions, impurity ion heating and electron heating due to Landau damping and TTMP. These mechanisms were studied in JET experiments with a ˜90% D, 5% H plasma including traces of Be and Ar. Up to 2MW of ICRH power was applied at 25 MHz to NBI heated plasmas. In most of the discharges the toroidal magnetic field strength was 3.3T, but in one it was equal to 3.6T. The E+ component of the electric field governs the ion cyclotron heating of not too fast particles. The Doppler shifted RF absorption of the beam deuterons away from the cold resonance at which E+ is small was exploited to enhance the RF power absorption efficiency. Fundamental ICRH experiments were also carried out in LHD hydrogen plasma with high energy hydrogen NBI. ICRH was performed at 38MHz with injected power <1 MW. The effect of fundamental ICRH was clearly demonstrated in both machines.

Krasilnikov, A. V.; Van Eester, D.; Lerche, E.; Ongena, J.; Mailloux, J.; Stamp, M.; Jachmich, S.; Leggate, H.; Vdovin, V.; Walden, A.; Mayoral, M.-L.; Bonheure, G.; Santala, M.; Kiptily, V.; Popovichev, S.; Biewer, T.; Crombe, K.; Esposito, B.; Marocco, D.; Riva, M.; Kaschuck, Yu. A.; Amosov, V. N.; Ericsson, G.; Giacomelli, L.; Hellesen, C.; Hjalmarsson, A.; Kallne, J.; Isobe, M.; Nishiura, M.; Sasao, M.; Nishimura, H.; Saito, K.; Seki, T.; Mutoh, T.; Kumazawa, R.; Takeiri, Y.; Osakabe, M.; Goto, M.; Murakami, S.; Goncharov, P.

2007-09-01

178

Power requirements for electron cyclotron current drive and ion cyclotron resonance heating for sawtooth control in ITER  

NASA Astrophysics Data System (ADS)

13 MW of electron cyclotron current drive (ECCD) power deposited inside the q = 1 surface is likely to reduce the sawtooth period in ITER baseline scenario below the level empirically predicted to trigger neoclassical tearing modes (NTMs). However, since the ECCD control scheme is solely predicated upon changing the local magnetic shear, it is prudent to plan to use a complementary scheme which directly decreases the potential energy of the kink mode in order to reduce the sawtooth period. In the event that the natural sawtooth period is longer than expected, due to enhanced ? particle stabilization for instance, this ancillary sawtooth control can be provided from >10MW of ion cyclotron resonance heating (ICRH) power with a resonance just inside the q = 1 surface. Both ECCD and ICRH control schemes would benefit greatly from active feedback of the deposition with respect to the rational surface. If the q = 1 surface can be maintained closer to the magnetic axis, the efficacy of ECCD and ICRH schemes significantly increases, the negative effect on the fusion gain is reduced, and off-axis negative-ion neutral beam injection (NNBI) can also be considered for sawtooth control. Consequently, schemes to reduce the q = 1 radius are highly desirable, such as early heating to delay the current penetration and, of course, active sawtooth destabilization to mediate small frequent sawteeth and retain a small q = 1 radius. Finally, there remains a residual risk that the ECCD + ICRH control actuators cannot keep the sawtooth period below the threshold for triggering NTMs (since this is derived only from empirical scaling and the control modelling has numerous caveats). If this is the case, a secondary control scheme of sawtooth stabilization via ECCD + ICRH + NNBI, interspersed with deliberate triggering of a crash through auxiliary power reduction and simultaneous pre-emptive NTM control by off-axis ECCD has been considered, permitting long transient periods with high fusion gain. The power requirements for the necessary degree of sawtooth control using either destabilization or stabilization schemes are expected to be within the specification of anticipated ICRH and ECRH heating in ITER, provided the requisite power can be dedicated to sawtooth control.

Chapman, I. T.; Graves, J. P.; Sauter, O.; Zucca, C.; Asunta, O.; Buttery, R. J.; Coda, S.; Goodman, T.; Igochine, V.; Johnson, T.; Jucker, M.; La Haye, R. J.; Lennholm, M.; Contributors, JET-EFDA

2013-06-01

179

Quality inspection of small diameter polymeric medical tubing and attached wire stent using TAP-NDE and the Gabor Wavelet Transform  

E-print Network

A non-contact, laser-optic based technique referred to as the Thermo-Acousto-Photonic Nondestructive Evaluation (TAP-NDE) was utilized to investigate bond integrity and localized stiffening due to an attached wire stent on small diameter polymeric...

Harms, Kent David

2012-06-07

180

Medical Scientists  

MedlinePLUS

... Those who go to medical school spend most of the first 2 years in labs and classrooms, taking courses such as anatomy, biochemistry, physiology, pharmacology, psychology, microbiology, pathology, medical ethics, and medical law. They ...

181

Botox (Medical)  

MedlinePLUS

... the Eye Glossary Current News How to Help Botox (Medical) Share with a friend Botox (Medical) A link to this article will be ... any list. Close without sharing. Give Us Feedback Botox (Medical) Your name First Name MI Laast Name ...

182

Oral Medication  

MedlinePLUS

... Size: A A A Listen En Español Oral Medication The first treatment for type 2 diabetes blood ... new — even over-the-counter items. Explore: Oral Medication How Much Do Oral Medications Cost? Save money ...

183

Status of electron cyclotron wave technology  

NASA Astrophysics Data System (ADS)

A review of the two key technologies for the electron cyclotron wave (ECW) system, the gyrotron source and the window, is presented. In both fields, significant progress has been made to meet the requirements of the heating and current drive systems planned for devices such as W7-X or ITER, namely 1 MW-CW (continuous wave) in the frequency range 140-170 GHz. Gyrotrons in this performance range have been tested in long pulse operation (many seconds). With the use of a diamond window, extremely long pulse $\\gg$ 10 s)

Tran, M. Q.

1998-08-01

184

Electron Cyclotron Resonances in Electron Cloud Dynamics  

SciTech Connect

We report a previously unknown resonance for electron cloud dynamics. The 2D simulation code"POSINST" was used to study the electron cloud buildup at different z positions in the International Linear Collider positron damping ring wiggler. An electron equilibrium density enhancement of up to a factor of 3 was found at magnetic field values for which the bunch frequency is an integral multiple of the electron cyclotron frequency. At low magnetic fields the effects of the resonance are prominent, but when B exceeds ~;;(2 pi mec/(elb)), with lb = bunch length, effects of the resonance disappear. Thus short bunches and low B fields are required for observing the effect. The reason for the B field dependence, an explanation of the dynamics, and the results of the 2D simulations and of a single-particle tracking code used to elucidate details of the dynamics are discussed.

Celata, Christine; Celata, C.M.; Furman, Miguel A.; Vay, J.-L.; Yu, Jennifer W.

2008-06-25

185

Beam cyclotron instability in a dusty plasma  

NASA Astrophysics Data System (ADS)

A beam cyclotron instability in a plasma composed of magnetized ions and electrons and unmagnetized, negatively charged dust is investigated using linear kinetic theory. We consider the case where an ion E × E drift leads to the excitation of a discrete wavenumber spectrum of waves with frequency on the order of the dust plasma frequency for propagation perpendicular to the magnetic field. The unstable wavelengths are short, on the order of the ion gyroradius. Collisions of charged particles with neutrals are taken into account, as well as ion-dust and dust-dust collisions, which can be significant at the lower pressures considered. The behavior of the instability for oblique propagation is also considered. Application to possible laboratory dusty magnetoplasma parameters is discussed.

Rosenberg, M.

2014-08-01

186

Folded waveguide coupler for ion cyclotron heating  

SciTech Connect

A new type of waveguide coupler for plasma heating in the ion cyclotron range of frequencies is described. The coupler consists of a series of interleaved metallic vanes within a rectangular enclosure analogous to a wide rectangular waveguide that has been ''folded'' several times. At the mouth of the coupler, a plate is attached which contains coupling apertures in each fold or every other fold of the waveguide, depending upon the wavenumber spectrum desired. This plate serves primarily as a wave field polarizer that converts coupler fields to the polarization of the fast magnetosonic wave within the plasma. Theoretical estimates indicate that the folded waveguide is capable of high-efficiency, multimegawatt operation into a plasma. Bench tests have verified the predicted field structure within the waveguide in preparation for high-power tests on the Radio Frequency Test Facility at the Oak Ridge National Laboratory.

Owens, T.L.; Chen, G.L.

1986-01-01

187

Encapsulated Target for Isotope Production Cyclotrons  

NASA Astrophysics Data System (ADS)

The current solid isotope production targets at TRIUMF can only be used to irradiate metallic materials with high melting point. In order to irradiate liquids, powders, and materials with low melting point, a new encapsulated target is being developed specifically for use on isotope production cyclotrons. This concentrically water-cooled target must withstand a 240 microA @ 30 MeV proton beam. The target is a round container with a pocket to hold the target material; the target material is encapsulated using a thin foil which is electron-beam welded on the target. The cooling and the heat-induced stresses of the target are being analyzed using finite element methods. The results will then be compared with actual measurements obtained using surface embedded thermocouples. The paper discusses the results and the current status of the project.

Bakhtiari, Shervin; Gelbart, William Z.; Ho, Wendy; Stevenson, Nigel R.

1997-05-01

188

Electron Cyclotron Heating in RFP plasmas  

SciTech Connect

Reversed field pinches (RFP) plasmas are typically overdense ({omega}{sub pe}>{omega}{sub ce}) and thus not suitable for conventional electron cyclotron (EC) heating and current drive. In recent high plasma current discharges (I{sub p}>1.5 MA), however, the RFX-mod device was operated in underdense conditions ({omega}{sub pe}<{omega}{sub ce}) for the first time in an RFP. Thus, it is now possible to envisage heating the RFP plasma core by conventional EC at the 2nd harmonic, in the ordinary or extraordinary mode. We present a preliminary study of EC-heating feasibility in RFX-mod with the use of beam-tracing and full-wave codes. Although not competitive - as a heating system - with multi-MW Ohmic heating in an RFP, EC might be useful for perturbative transport studies, even at moderate power (hundreds of kW), and, more generally, for applications requiring localized power deposition.

Bilato, R.; Poli, E. [MPI fuer Plasmaphysik-Euratom Association Boltzmannstr. 2, D-85748 Garching (Germany); Volpe, F. [Department of Engineering Physics, University of Wisconsin, Madison, WI (United States); Koehn, A. [Institut fuer Plasmaforschung, Universitaet Stuttgart-Stuttgart (Germany); Cavazzana, R.; Paccagnella, R. [Consorzio RFX-Associazione EURATOM-ENEA sulla fusione-Padova (Italy); Farina, D. [IFP-CNR, EURATOM-ENEA-CNR Association-Milano (Italy)

2009-11-26

189

Positron emission isotope production cyclotron in DLNP JINR (Status Report)  

NASA Astrophysics Data System (ADS)

A C10-cyclotron for radioisotope production is under construction at the Dzhelepov Laboratory of Nuclear Problem, Joint Institute for Nuclear Research (DLNP JINR). It is a compact isochronous cyclotron for accelerating H- ions to the energy of about 10 MeV. The magnetic system, vacuum chamber and accelerating system is being built now. Results of the calculation and forming of the cyclotron magnetic field and the study of the beam dynamics from an ion source to an extraction system in calculated magnetic field are presented.

Alenitsky, Yu. G.; Denisov, Yu. N.; Chesnov, A. F.; Glazov, A. A.; Gurskiy, S. V.; Karamysheva, G. A.; Kostromin, S. A.; Morozov, N. A.; Romanov, V. M.; Samsonov, E. V.; Tolstoi, N. S.; Zaplatin, N. L.

2008-12-01

190

The NSCL cyclotron gas stopper - Under construction  

NASA Astrophysics Data System (ADS)

Rare isotopes are produced at the NSCL by projectile fragmentation at energies on the order of 100 MeV/u for a wide range of research. In order to provide these exotic ions to low-energy high precision experiments such as the Penning-trap mass spectrometer LEBIT and the collinear laser spectroscopy setup, or to the NSCL's re-accelerator (ReA), the beam must be slowed down into the eV range by solid degraders and interaction with buffer gas. A novel gas-filled reverse cyclotron is currently under construction by the NSCL and will complement a recently installed linear gas-filled cell. The new device is based on a 2.6 T maximum-field cyclotron-type three-sectored magnet to confine the injected beam while it is slowed down in ?100 mbar of high-purity helium gas, cooled to liquid-nitrogen temperature. Once thermalized, the beam is transported to the center of the device by a novel RF-carpet system, extracted along the symmetry axis and accelerated to a few tens of keV of energy for delivery to the users. The device has been characterized in numerous simulations with full 3D models of its magnetic field. The beam transport has been modeled from the fragment separator to the point where they reach thermal energies. The simulations indicate that very efficient stopping and fast extraction will be possible even for light and medium-mass ions, which are difficult to efficiently thermalize in linear gas cells. Construction of the device is well underway and initial tests are planned for later this year. The design and the predicted performance of the machine is discussed and its construction status is given.

Schwarz, S.; Bollen, G.; Brodeur, M.; Chouhan, S. S.; DeKamp, J.; Gehring, A. E.; Joshi, N. S.; Magsig, C.; Morrissey, D. J.; Ringle, R.; Ottarson, J.; Zeller, A. F.

2013-12-01

191

Medical telesensors  

NASA Astrophysics Data System (ADS)

Medical telesensors are self-contained integrated circuits for measuring and transmitting vital signs over a distance of approximately 1-2 meters. The circuits are unhoused and contain a sensor, signal processing and modulation electronics, a spread-spectrum transmitter, an antenna and a thin-film battery. We report on a body-temperature telesensor, which is sufficiently small to be placed on a tympanic membrane in a child's ear. We also report on a pulse-oximeter telesensor and a micropack receiver/long- range transmitter unit, which receives form a telesensor array and analyzes and re-transmits the vital signs over a longer range. Signal analytics are presented for the pulse oximeter, which is currently in the form of a finger ring. A multichip module is presented as the basic signal-analysis component. The module contains a microprocessor, a field=programmable gate array, memory elements and other components necessary for determining trauma and reporting signals.

Ferrell, Trinidad L.; Crilly, P. B.; Smith, S. F.; Wintenberg, Alan L.; Britton, Charles L., Jr.; Morrison, Gilbert W.; Ericson, M. N.; Hedden, D.; Bouldin, Donald W.; Passian, A.; Downey, Todd R.; Wig, A. G.; Meriaudeau, Fabrice

1998-05-01

192

Detection of small trace molecules in human and animal exhalation by tunable diode lasers for applications in biochemistry and medical diagnostics  

NASA Astrophysics Data System (ADS)

Tunable diode laser spectroscopy (TDLS) is proposed for content measurements of trace gases like CO, CO2, NH3, CH4, NO, NO2 in human and animal exhalation. High sensitivity and wide dynamic range of the method ensure fast detection of these gases at ppb level and within the accuracy better than 10%. One-expiration sample is enough to reach these parameters. There is no need for any preliminary preparations of tested samples. Some pairs of the gases, for instance, CO and CO2, NH3 and CO2 and CO and N2O, can be measured simultaneously by one laser providing complex studies. The high sensitive gas analysis could provide necessary background to the noninvasive diagnostics in a wide variety of medical problems. Perspectives of the TDLS methods in application to medicine diagnostics are demonstrated by the first results of exhalation tests.

Stepanov, Eugene V.; Kouznetsov, Andrian I.; Zyrianov, Pavel V.; Skrupskii, Vladimir A.; Shulagin, Yurii A.; Galagan, Marina E.

1995-02-01

193

Currents induced in tokamaks by electron cyclotron heating  

SciTech Connect

Generation of a plasma current is predicted in association with strong electron cyclotron heating in tokamaks or in any plasma with transverse magnetic field gradients. The current predicted in present-day tokamaks is of the order of one-quarter ampere per watt, which is large enough to be detected in heating experiments in progress. The current scales linearly with electron temperature and heating power and inversely with density and major radius. The mechanism depends on the Doppler shift for electrons streaming along magnetic field lines. Electrons streaming toward the source of radiation are resonant at a larger magnetic field. When the interaction is strong, radiation incident from the high field side is absorbed before reaching the cold electron resonant surface, and, so, a unidirectional population of electrons is heated. The anisotropic electron distribution gains momentum by collisions with ions. For small tokamaks the extraordinary wave should be launched for current drive, but for reactors the ordinary wave produces a sufficiently strong interaction.

Eldridge, O. C.

1980-10-01

194

Ion cyclotron transmission spectroscopy in the Tokamak Fusion Test Reactor  

SciTech Connect

The propagation of waves in the ion cyclotron range of frequencies has been investigated experimentally in the Tokamak Fusion Test Reactor. A small, broadband, radiofrequency (rf) magnetic probe located outside the plasma limiter, at a major radius near that of the plasma center, was excited with a low power, frequency swept source (1--200 MHz). Waves propagating to a distant location were detected with a second, identical probe. The rf transmission spectrum revealed a region of attenuation over a band of frequencies for which the minority fundamental resonance was located between the outer plasma edge and the major radius of the probe location. Distinct, non-overlapping attenuation bands were observed from hydrogen and helium-3 minority species; a distinct tritium band should be observed in future DT experiments. Rapid spectrum acquisition during a helium-3 gas puff experiment showed that the wave attenuation involved the plasma core and was not a surface effect. A model in which the received power varied exponentially with the minority density, averaged over the resonance region, fit the time evolution of the probe signal relatively well. Estimation of a 1-d tunneling parameter from the experimental observations is discussed. Minority concentrations of less than 0.5 % can be resolved with this measurement.

Greene, G.J.

1993-09-01

195

A line-of-sight electron cyclotron emission receiver for electron cyclotron resonance heating feedback control of tearing modes  

NASA Astrophysics Data System (ADS)

An electron cyclotron emission (ECE) receiver inside the electron cyclotron resonance heating (ECRH) transmission line has been brought into operation. The ECE is extracted by placing a quartz plate acting as a Fabry-Perot interferometer under an angle inside the electron cyclotron wave (ECW) beam. ECE measurements are obtained during high power ECRH operation. This demonstrates the successful operation of the diagnostic and, in particular, a sufficient suppression of the gyrotron component preventing it from interfering with ECE measurements. When integrated into a feedback system for the control of plasma instabilities this line-of-sight ECE diagnostic removes the need to localize the instabilities in absolute coordinates.

Oosterbeek, J. W.; Bürger, A.; Westerhof, E.; de Baar, M. R.; van den Berg, M. A.; Bongers, W. A.; Graswinckel, M. F.; Hennen, B. A.; Kruijt, O. G.; Thoen, J.; Heidinger, R.; Korsholm, S. B.; Leipold, F.; Nielsen, S. K.

2008-09-01

196

A Doppler Shift model to explain the Cyclotron Line Variability in X-Ray Pulsars  

E-print Network

A simple model to explain the phase-dependence of the cyclotron absorption line observed in many X-Ray pulsars is presented. It includes several relativistic effects, namely gravitational redshift, gravitational light deflection, and - most important - doppler shift of the photon energy in the infalling plasma. It is shown that previous estimates of neutron star magnetic fields neglecting the last effect give results which are too small by about a factor of two. Finally the developed equations are used to determine the neutron star radius and magnetic field of Her X-1, but the large uncertainties in the geometry prevent the results from seriously constraining the parameters.

C. Weth

2001-01-03

197

Single electron detection and spectroscopy via relativistic cyclotron radiation  

E-print Network

It has been understood since 1897 that accelerating charges must emit electromagnetic radiation. Cyclotron radiation, the particular form of radiation emitted by an electron orbiting in a magnetic field, was first derived in 1904. Despite the simplicity of this concept, and the enormous utility of electron spectroscopy in nuclear and particle physics, single-electron cyclotron radiation has never been observed directly. Here we demonstrate single-electron detection in a novel radiofrequency spec- trometer. We observe the cyclotron radiation emitted by individual magnetically-trapped electrons that are produced with mildly-relativistic energies by a gaseous radioactive source. The relativistic shift in the cyclotron frequency permits a precise electron energy measurement. Precise beta elec- tron spectroscopy from gaseous radiation sources is a key technique in modern efforts to measure the neutrino mass via the tritium decay endpoint, and this work demonstrates a fundamentally new approach to precision beta sp...

Asner, D M; de Viveiros, L; Doe, P J; Fernandes, J L; Fertl, M; Finn, E C; Formaggio, J A; Furse, D; Jones, A M; Kofron, J N; LaRoque, B H; Leber, M; McBride, E L; Miller, M L; Mohanmurthy, P; Monreal, B; Oblath, N S; Robertson, R G H; Rosenberg, L J; Rybka, G; Rysewyk, D; Sternberg, M G; Tedeschi, J R; Thummler, T; VanDevender, B A; Woods, N L

2014-01-01

198

Single electron detection and spectroscopy via relativistic cyclotron radiation  

E-print Network

It has been understood since 1897 that accelerating charges must emit electromagnetic radiation. Cyclotron radiation, the particular form of radiation emitted by an electron orbiting in a magnetic field, was first derived in 1904. Despite the simplicity of this concept, and the enormous utility of electron spectroscopy in nuclear and particle physics, single-electron cyclotron radiation has never been observed directly. Here we demonstrate single-electron detection in a novel radiofrequency spec- trometer. We observe the cyclotron radiation emitted by individual magnetically-trapped electrons that are produced with mildly-relativistic energies by a gaseous radioactive source. The relativistic shift in the cyclotron frequency permits a precise electron energy measurement. Precise beta elec- tron spectroscopy from gaseous radiation sources is a key technique in modern efforts to measure the neutrino mass via the tritium decay endpoint, and this work demonstrates a fundamentally new approach to precision beta spectroscopy for future neutrino mass experiments.

D. M. Asner; R. F. Bradley; L. de Viveiros; P. J. Doe; J. L. Fernandes; M. Fertl; E. C. Finn; J. A. Formaggio; D. Furse; A. M. Jones; J. N. Kofron; B. H. LaRoque; M. Leber; E. L. McBride; M. L. Miller; P. Mohanmurthy; B. Monreal; N. S. Oblath; R. G. H. Robertson; L. J Rosenberg; G. Rybka; D. Rysewyk; M. G. Sternberg; J. R. Tedeschi; T. Thummler; B. A. VanDevender; N. L. Woods

2014-08-22

199

NORTICA—a new code for cyclotron analysis  

NASA Astrophysics Data System (ADS)

The new package NORTICA (Numerical ORbit Tracking In Cyclotrons with Analysis) of computer codes for beam dynamics simulations is under development at NSCL. The package was started as a replacement for the code MONSTER [1] developed in the laboratory in the past. The new codes are capable of beam dynamics simulations in both CCF (Coupled Cyclotron Facility) accelerators, the K500 and K1200 superconducting cyclotrons. The general purpose of this package is assisting in setting and tuning the cyclotrons taking into account the main field and extraction channel imperfections. The computer platform for the package is Alpha Station with UNIX operating system and X-Windows graphic interface. A multiple programming language approach was used in order to combine the reliability of the numerical algorithms developed over the long period of time in the laboratory and the friendliness of modern style user interface. This paper describes the capability and features of the codes in the present state.

Gorelov, D.; Johnson, D.; Marti, F.

2001-12-01

200

Multiple frequency electron cyclotron heating for the Levitated Dipole Experiment  

E-print Network

The use of multiple frequencies of electron cyclotron resonance heating (ECRH) in the Levitated Dipole Experiment (LDX) is an important tool that will tailor the plasma profiles. Initial LDX plasmas have been created using ...

Mahar, Scott B

2005-01-01

201

Flat-top system of the DC-280 cyclotron  

NASA Astrophysics Data System (ADS)

The flat-top cavity of the radio-frequency accelerating system designed at the Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, for the DC-280 cyclotron is described. The cyclotron is intended for increasing the capabilities and efficiency of experiments on the synthesis of super-heavy elements and an investigation of their nuclear physical and chemical properties. The DC-280 isochronous heavy-ion cyclotron will produce accelerated beam of ions in the range from neon to uranium. The parameters, design, and results of the experimental and 3D computer modeling of the flat-top cavity of the RF accelerating system of the DC-280 cyclotron are reported.

Gulbekyan, G. G.; Buzmakov, V. A.; Zarubin, V. B.; Ivanenko, I. A.; Kazarinov, N. Yu.; Karamysheva, G. A.; Franko, I.

2013-07-01

202

Cyclotron radiation by a multi-group method  

SciTech Connect

A multi-energy group technique is developed to study conditions under which cyclotron radiation emission can shift a Maxwellian electron distribution into a non-Maxwellian; and if the electron distribution is non-Maxwellian, to study the rate of cyclotron radiation emission as compared to that emitted by a Maxwellian having the same mean electron density and energy. The assumptions in this study are: the electrons should be in an isotropic medium and the magnetic field should be uniform. The multi-group technique is coupled into a multi-group Fokker-Planck computer code to study electron behavior under the influence of cyclotron radiation emission in a self-consistent fashion. Several non-Maxwellian distributions were simulated to compare their cyclotron emissions with the corresponding energy and number density equivalent Maxwellian distribtions.

Chu, T.C.

1980-01-01

203

Cyclotrons for clinical and biomedical research with PET  

SciTech Connect

The purpose of this commentary is to present some background material on cyclotrons and other particle accelerators particularly with a view toward the considerations behind acquiring and installing such a machine for purely clinical and/or biomedical research use.

Wolf, A.P.

1987-01-01

204

Dispersion relation of electromagnetic ion cyclotron waves using Cluster observations  

E-print Network

Multi-point wave observations on Cluster spacecraft are used to infer the dispersion relation of electromagnetic ion cyclotron (EMIC) waves. In this study we use a phase differencing method and observations from STAFF and ...

Pakhotin, I. P.

205

Medical Matrix  

NSDL National Science Digital Library

Medical Matrix is a Web resource that offers a database of Internet clinical medicine resources. Medical Matrix categorizes resources by disease, specialty, and other interest areas. It is designed as a "home page" for a physician's or healthworker's computer. Medical Matrix is a project of the Internet Working Group of the American Medical Informatics Association.

206

Cyclotron Resonance Vanishing effect in Correlated 2D Electron Systems  

Microsoft Academic Search

``Cyclotron Resonance - Vanishing effect'' (CRV) arise on magnetospectra of cyclotron resonance line (CR) as a well-defined gap that reduce to zero CR effect. CRV have been discovered due to experimental study of terahertz radiation transmission and photoresistivity magnetospectra at CR conditions in two-dimensional electron system (2DES) of GaAs\\/AlGaAs nanostructures with higher electron mobility at low (non-quantized Hall effect) magnetic

Andre Chebotarev; Galina Chebotareva

2009-01-01

207

PET computer programs for use with the 88-inch cyclotron  

SciTech Connect

This report describes in detail several offline programs written for the PET computer which provide an efficient data management system to assist with the operation of the 88-Inch Cyclotron. This function includes the capability to predict settings for all cyclotron and beam line parameters for all beams within the present operating domain of the facility. The establishment of a data base for operational records is also described from which various aspects of the operating history can be projected.

Gough, R.A.; Chlosta, L.

1981-06-01

208

Status and development of the Kazakhstan isochronous cyclotron  

NASA Astrophysics Data System (ADS)

A report is presented on the status of the cyclotron in Almaty at present time. In spite of sharp curtailment of government-funded basic research program the cyclotron still remains as multipurpose accelerator facility and is being used for fundamental research and application in different fields of applied science. During last years some cyclotron systems were upgraded and some were designed anew. The system for on-line precise ion beam energy measurement using time-of-flight method was designed and constructed. Inductive pick-up electrodes are integrated into beam transport channel and are located at the distance of 10 m from each other. Average beam energy determination is performed with the accuracy about 0.1%. This system allows to analyze ion beam parameters in pulse-mode of cyclotron operation with macro duty factor in the range of 2-50. In connection with development of cyclotron based radioisotope production and necessity of irradiation of toxic materials and loose and smelted powders with low heat conductivity circular beam scanning system was designed and installed. Transversal rotating magnetic field is generated by stator of usual electro-motor. The scanner allows to form predictable beam power density distribution on the target surface and obtain rather uniform irradiation fields. Cyclotron based neutron source with Be target for research on radioecology and neutron dosimetry was constructed and is located at one of the external beam transportation channel. Parameters of the system and examples of its application are presented.

Arzumanov, A.; Batischev, V.; Borissenko, A.; Gorkovets, M.; Koptev, V.; Lyssukhin, S.; Mulgin, S.; Popov, Yu.; Zhdanov, S.

2001-12-01

209

Electromagnetic ion cyclotron waves at proton cyclotron C. C. Chaston, J. W. Bonnell, J. P. McFadden, R. E. Ergun, and C. W. Carlson  

E-print Network

Electromagnetic ion cyclotron waves at proton cyclotron harmonics C. C. Chaston, J. W. Bonnell, J of auroral particle acceleration. In areas of upward current, large- amplitude electromagnetic waves. Bonnel, J. P. McFadden, R. E. Ergun, and C. W. Carlson, Electromagnetic ion cyclotron waves at proton

California at Berkeley, University of

210

Heating of O sup + ions in the cusp/cleft: Double-cyclotron absorption versus cyclotron resonance  

SciTech Connect

The process of double-cyclotron absorption, where an ion simultaneously absorbs two waves whose frequencies sum to the ion gyrofrequency, can heat ions perpendicular to the ambient magnetic field. It has been suggested that this process may play a role in the production of ion conics. The low-energy oxygen (O{sup +}) distributions and the electric spectral densities observed by DE 1 in the cusp/cleft during an O{sup +} conic event are used as inputs to a Monte Carlo simulation of the heating of the O{sup +} ions due to double-cyclotron absorption of waves near half the ion gyrofrequency. The results are compared with the observed O{sup +} conics and with the results of simulations of ion heating via the process of cyclotron resonance involving left-hand polarized waves near the ion gyrofrequency. The simulations show that for any particular event cyclotron resonance can probably heat ions over a much greater altitude range than double-cyclotron absorption is capable of doing. They also demonstrate the much stronger dependence of the heating due to double-cyclotron absorption on local intensifications of the spectral density, and they indicate that a relatively narrow region of intense wave activity may be sufficient for this heating process to produce O{sup +} conics with energies comparable to those observed. Heating via double-cyclotron absorption may therefore be important for relatively local heating of O{sup +} ions. However, cyclotron resonance heating by waves around the gyrofrequency is probably more important in the majority of O{sup +} conic events in the cusp/cleft.

Ball, L.; Andre, M. (University of Umea (Sweden))

1991-02-01

211

Effective dose to immuno-PET patients due to metastable impurities in cyclotron produced zirconium-89  

NASA Astrophysics Data System (ADS)

Immuno-PET is a nuclear medicine technique that combines positron emission tommography (PET) with radio-labeled monoclonal antibodies (mAbs) for tumor characterization and therapy. Zirconium-89 (89Zr) is an emerging radionuclide for immuno-PET imaging. Its long half-life (78.4 h) gives ample time for the production, the administering and the patient uptake of the tagged radiopharmaceutical. Furthermore, the nuclides will remain in the tumor cells after the mAbs are catabolized so that time series studies are possible without incurring further administration of radiopharmarceuticals. 89Zr can be produced in medical cyclotrons by bombarding an yttrium-89 (89Y) target with a proton beam through the 89Y(p,n)89Zr reaction. In this study, we estimated the effective dose to the head and neck cancer patients undergoing 89Zr-based immune-PET procedures. The production of 89Zr and the impurities from proton irradiation of the 89Y target in a cyclotron was calculated with the Monte Carlo code MCNPX and the nuclear reaction code TALYS. The cumulated activities of the Zr isotopes were derived from real patient data in literature and the effective doses were estimated using the MIRD specific absorbed fraction formalism. The estimated effective dose from 89Zr is 0.5±0.2 mSv/MBq. The highest organ dose is 1.8±0.2 mSv/MBq in the liver. These values are in agreement with those reported in literature. The effective dose from 89mZr is about 0.2-0.3% of the 89Zr dose in the worst case. Since the ratio of 89mZr to 89Zr depends on the cooling time as well as the irradiation details, contaminant dose estimation is an important aspect in optimizing the cyclotron irradiation geometry, energy and time.

Alfuraih, Abdulrahman; Alzimami, Khalid; Ma, Andy K.; Alghamdi, Ali; Al Jammaz, Ibrahim

2014-11-01

212

Modelling of Ion Cyclotron Wall Conditioning plasmas  

SciTech Connect

Ion Cyclotron Wall Conditioning (ICWC) is envisioned in ITER to clean the wall from impurities, to control the wall isotopic ratio and the hydrogen recycling in the presence of the toroidal magnetic field. Various experiments and modelling are advancing to consolidate this technique. In this contribution the modeling of ICWC is presented, which can be divided in two parts: plasma description and plasma wall interaction. Firstly a 0D plasma model, based on a set of energy and particle balance equations for Maxwellian Hydrogen and Helium species, is presented. The model takes into account elementary collision processes, coupled RF power, particle confinement, wall recycling, and active gas injection and pumping. The RF plasma production process is based mainly on electron collisional ionization. The dependency of the plasma parameters, the Hydrogen and Helium partial pressures and neutral or ionic fluxes on pressure and RF power are quantitatively in good agreement with those obtained experimentally on TORE SUPRA. Secondly an extension of the 0D model including the description of the wall interaction is presented and compared to TORE SUPRA multi-pulse ICWC discharges.

Douai, D.; Wauters, T.; Wuenderlich, D.; Bremond, S.; Lombard, G.; Mollard, P.; Pegourie, B. [CEA, IRFM, 13108 St Paul lez Durance (France); Lyssoivan, A. [LPP-ERM/KMS, 1000 Brussels (Belgium); Marchuk, O. [IEK-4, FZ Juelich, 52425 Juelich (Germany); Van Oost, G. [Ghent University, 9000 Ghent (Belgium)

2011-12-23

213

Proton cyclotron waves at Mars revisited  

NASA Astrophysics Data System (ADS)

The presence of waves measured by the Mars Global Surveyor magnetometer and electron reflectometer (MAG/ER) at the local proton cyclotron frequency in the solar wind revealed the presence of an extended exosphere at Mars. However, the large amplitude of these waves even at large distances and their non linear nature make the pickup ion rates from local exospheric hydrogen deduced from classical quasi-linear theory sometimes unrealistically high. Some previous studied cases have shown intermittent observations which have been interpreted as consistent with the crossing of a disc distribution of energetic neutral atoms formed by recombination or charge exchange with pickup ions produced closer to the planet. This disc distribution is supposed to depend on the local IMF direction where the ENAs have been created. However there are numerous cases showing continuous waves along many orbits with the same orientation in space while the IMF obviously can be very different. This makes the possibility for the spacecraft to remain inside the hypothetic ENA disc very unlikely. In this work, we present new analyses of high resolution measurements of Mars Global Surveyor magnetometer and electron spectrometer during the aerobraking hiatus (science phasing orbits). The statistic of wave amplitude in 3D space will be shown. Comparison with observations by Mars Express SPICAM instrument will help to obtain new insights in the connection between the spatial distribution of these waves and the geometry of the Martian hydrogen exosphere. Implications for the future Maven mission will be discussed.

Mazelle, C. X.; Bertucci, C.; Trotignon, J.; Sauer, K.; Bertaux, J.; Chaufray, J.

2009-12-01

214

Cyclotron-based effects on plant gravitropism  

NASA Astrophysics Data System (ADS)

Primary roots exhibit positive gravitropism and grow in the direction of the gravitational vector, while shoots respond negatively and grow opposite to the gravitational vector. We first demonstrated that the use of a weak combined magnetic field (CMF), which is comprised of a permanent magnetic field and an alternating magnetic field with the frequency resonance of the cyclotron frequency of calcium ions, can change root gravitropism from a positive direction to negative direction. Two-day-old cress seedlings were gravistimulated in a chamber that was placed into a ?-metal shield where this CMF was created. Using this "new model" of a root gravitropic response, we have studied some of its components including the movement of amyloplasts-statoliths in root cap statocytes and the distribution of Ca 2+ ions in the distal elongation zone during gravistimulation. Unlike results from the control, amyloplasts did not sediment in the distal part of a statocyte, and more Ca 2+ accumulation was observed in the upper side of a gravistimulated root for seedlings treated with the CMF. For plants treated with the CMF, it appears that a root gravitropic reaction occurs by a normal physiological process resulting in root bending although in the opposite direction. These results support the hypothesis that both the amyloplasts in the root cap statocytes and calcium are important signaling components in plant gravitropism.

Kordyum, E.; Sobol, M.; Kalinina, Ia.; Bogatina, N.; Kondrachuk, A.

215

Ferrite-guided cyclotron-resonance maser.  

PubMed

The concept of a cyclotron-resonance maser (CRM) with a ferrite loading incorporated in its waveguide is proposed. The CRM interaction occurs between the rotating electron beam and the em wave propagating along a longitudinally magnetized ferrite medium. The ferrite anisotropic permeability resembles the CRM susceptibility in many aspects, and particularly in their similar response to the axial magnetic field (the ferrite susceptibility can be regarded as a passive analog of the active CRM interaction). The ferrite loading slows down the phase velocity of the em wave and thus the axial (Weibel) mechanism of the CRM interaction dominates. The ferrite loading enables also a mechanism of spectral tunability for CRM's. The ferrite loading is proposed, therefore, as a useful ingredient for high-power CRM devices. A linear model of the combined ferrite-guided CRM interaction reveals its useful features. Future schemes may also incorporate ferrite sections functioning as isolators, gyrators, or phase shifters within the CRM device itself for selective suppression of backward waves and spurious oscillations, and for gain and efficiency enhancement. PMID:12188841

Jerby, Eli; Kesar, A; Aharony, A; Breitmeier, G

2002-06-01

216

The Oak Ridge Isochronous Cyclotron Refurbishment Project  

SciTech Connect

The Oak Ridge Isochronous Cyclotron (ORIC) has been in operation for nearly fifty years at the Oak Ridge National Laboratory (ORNL). Presently, it serves as the driver accelerator for the ORNL Holifield Radioactive Ion Beam Facility (HRIBF), where radioactive ion beams are produced using the Isotope Separation Online (ISOL) technique for post-acceleration by the 25URC tandem electrostatic accelerator. Operability and reliability of ORIC are critical issues for the success of HRIBF and have presented increasingly difficult operational challenges for the facility in recent years. In February 2010, a trim coil failure rendered ORIC inoperable for several months. This presented HRIBF with the opportunity to undertake various repairs and maintenance upgrades aimed at restoring the full functionality of ORIC and improving the reliability to a level better than what had been typical over the previous decade. In this paper, we present details of these efforts, including the replacement of the entire trim coil set and measurements of their radial field profile. Comparison of measurements and operating tune parameters with setup code predictions will also be presented.

Mendez, II, Anthony J [ORNL; Ball, James B [ORNL; Dowling, Darryl T [ORNL; Mosko, Sigmund W [ORNL; Tatum, B Alan [ORNL

2011-01-01

217

Medical neglect.  

PubMed

Medical neglect occurs when children are harmed or placed at significant risk of harm by gaps in their medical care. This is most likely to occur and to be recognized when families lack resources, commonly due to poverty, and when medical demands are high, such as with complex, severe, and chronic illness. A systematic evaluation of the probabilities for harm from gaps in care versus benefits from improved care will define medical neglect. A broad consideration of child, family, community, and medical system contributions to identified gaps will guide management. Special circumstances, such as lapsed immunizations, unremitting obesity, and medically motivated alterations in care, are often challenging for medical providers. Guidance for these specific situations is available from the American Academy of Pediatrics, and from the medical literature. [Pediatr Ann. 2014;43(11):e253-e259.]. PMID:25369577

Boos, Stephen C; Fortin, Kristine

2014-11-01

218

Taking Medication  

MedlinePLUS

... Educator Questions, Comments, Concerns? 800 . 338 . 3633 Taking Medication Diabetes is a progressive condition. Depending on what ... healthcare team will be able to determine which medications they should be taking and help them understand ...

219

COPD Medications  

MedlinePLUS

... Lung Disease > COPD > Treating COPD Managing Your COPD Medications There are a variety of medicines available to ... if it is time for your pneumonia vaccine. Medication Management Tips COPD medicines do not cure COPD ...

220

Medication Guide  

MedlinePLUS

... of medications are currently in use to treat glaucoma. Your doctor may prescribe a combination of medications ... the optic nerve. Eye drops used in managing glaucoma decrease eye pressure by helping the eye’s fluid ...

221

Quasi-steady, marginally unstable electron cyclotron harmonic wave amplitudes  

NASA Astrophysics Data System (ADS)

Electron cyclotron harmonic (ECH) waves have long been considered a potential driver of diffuse aurora in Earth's magnetotail. However, the scarcity of intense ECH emissions in the outer magnetotail suggests that our understanding of the amplification and the relative importance of these waves for electron scattering is lacking. We conduct a comprehensive study of wave growth and quasi-linear diffusion to estimate the amplitude of loss-cone-driven ECH waves once diffusion and growth balance but before convection or losses alter the background hot plasma sheet population. We expect this to be the most common state of the plasma sheet between episodes of fast convection. For any given wave amplitude, we model electron diffusion caused by interaction with ECH waves using a 2-D bounce-averaged Fokker-Planck equation. After fitting the resultant electron distributions as a superposition of multicomponent subtracted bi-Maxwellians, we estimate the maximum path-integrated gain using the HOTRAY ray-tracing code. We argue that the wave amplitude during quasi-steady state is the inflection point on a gain-amplitude curve. During quasi-steady state, ECH wave amplitudes can be significant (~1 mV/m) at L ~ 8 but drop to very low values (<~0.1 mV/m) in the outer magnetotail (L ~ 16) and likely fall below the sensitivity of typical instrumentation relatively close to Earth mainly because of the smallness of the loss cone. Our result reinforces the potentially important role of ECH waves in driving diffuse aurora and suggests that careful comparison of theoretical wave amplitude estimates and observations is required for resolving the equatorial scattering mechanism of diffuse auroral precipitation.

Zhang, Xiaojia; Angelopoulos, Vassilis; Ni, Binbin; Thorne, Richard M.; Horne, Richard B.

2013-06-01

222

Medical Marijuana  

MedlinePLUS

... the lower right-hand corner of the player. Medical Marijuana HealthDay August 26, 2014 Related MedlinePlus Pages Chronic ... the American Medical Association found that states with medical marijuana laws had an average 25% lower opiate overdose ...

223

Psychiatric Medication  

Microsoft Academic Search

This exploratory, descriptive study assessed psychiatric medication use in two samples. Students in three social work courses and practicing social workers in a midwestern city were surveyed by mail. Respondents were asked to identify symptoms, psychiatric medication use, effectiveness of drug therapy, side effects, stigma, and to rate the impact of psychiatric medication use on their current or future social

Jennifer Davis-Berman; H. Frances Pestello

2002-01-01

224

Heavy ion cocktail beams at the 88 inch Cyclotron  

SciTech Connect

Cyclotrons in combination with ECR ion sources provide the ability to accelerate ''cocktails'' of ions. A cocktail is a mixture of ions of near-identical mass-to-charge (m/q) ratio. The different ions cannot be separated by the injector mass-analyzing magnet and are tuned out of the ion source together. The cyclotron then is utilized as a mass analyzer by shifting the accelerating frequency. This concept was developed soon after the first ECR ion source became operational at the 88-Inch Cyclotron and has since become a powerful tool in the field of heavy ion radiation effects testing. Several different ''cocktails'' at various energies are available at the 88-Inch cyclotron for radiation effect testing, covering a broad range of linear energy transfer and penetration depth. Two standard heavy ion cocktails at 4.5 MeV/nucleon and 10 MeV/nucleon have been developed over the years containing ions from boron to bismuth. Recently, following requests for higher penetration depths, a 15MeV/nucleon heavy ion cocktail has been developed. Up to nine different metal and gaseous ion beams at low to very high charge states are tuned out of the ion source simultaneously and injected together into the cyclotron. It is therefore crucial to balance the ion source very carefully to provide sufficient intensities throughout the cocktail. The paper describes the set-up and tuning of the ion source for the various heavy ion cocktails.

Leitner, Daniela; McMahan, Margaret A.; Argento, David; Gimpel, Thomas; Guy, Aran; Morel, James; Siero, Christine; Thatcher, Ray; Lyneis, Claude M.

2002-09-03

225

Generation of Electromagnetic Bursts in the Plasma Cyclotron Maser  

NASA Astrophysics Data System (ADS)

We study experimentally the frequency and energy characteristics of electromagnetic waves in the plasma cyclotron maser, where the active medium is the two-component nonequilibrium plasma of an electron cyclotron resonance (ECR) discharge, which is produced by a high-power gyrotron radiation in a mirror trap. At the plasma decay stage, high-power (up to 200 W) pulses of electromagnetic radiation are detected synchronously with the precipitation of energetic electrons from the trap. This radiation propagates across the magnetic trap, and the radiation frequency fits in the interval between the electron gyrofrequency at the center of the mirror and the frequency of the electron cyclotron resonance heating. Synchronicity of the generated radiation with the electron precipitation out of the trap, as well as the dependence of the radiation frequency on the magnetic field of the trap, confirm the cyclotron mechanism of the arising instability. It is shown that electron precipitation, which is due to the cyclotron instability of the low-density plasma, ensures fast relaxation (as compared with the loss due to the Coulomb collisions) of the energy stored in the hot component of the plasma.

Viktorov, M. E.; Vodopyanov, A. V.; Golubev, S. V.; Izotov, I. V.; Mansfeld, D. A.

2013-06-01

226

Numerical analysis on the synergy between electron cyclotron current drive and lower hybrid current drive in tokamak plasmas  

NASA Astrophysics Data System (ADS)

The synergy between electron cyclotron current drive (ECCD) and lower hybrid current drive (LHCD) is investigated numerically with the parameters of the HL-2A tokamak. Based on the understanding of the synergy mechanisms, a high current driven efficiency or a desired radial current profile can be achieved through properly matching the parameters of ECCD and LHCD due to the flexibility of ECCD. Meanwhile, it is found that the total current driven by the electron cyclotron wave (ECW) and the lower hybrid wave (LHW) simultaneously can be smaller than the sum of the currents driven by the ECW and LHW separately, when the power of the ECW is much larger than the LHW power. One of the reasons leading to this phenomenon (referred to as negative synergy in this context) is that fast current-carrying electrons tend to be trapped, when the perpendicular velocity driven by the ECW is large and the parallel velocity decided by the LHW is correspondingly small.

Chen, S. Y.; Hong, B. B.; Liu, Y.; Lu, W.; Huang, J.; Tang, C. J.; Ding, X. T.; Zhang, X. J.; Hu, Y. J.

2012-11-01

227

Evolution of electron distributions in electrostatic ion cyclotron waves with associated parallel electric field and analysis of resulting instabilities  

NASA Astrophysics Data System (ADS)

The evolution of electron distribution in an electrostatic ion cyclotron wave, and the resulting induction of anomalous resistivity and a parallel electric field, are analyzed. The results show that the distribution can be divided into two groups, a trapped part and a runaway part. Two-stream instability can flatten the distribution of the runaway electrons, resulting in a distribution with a long and flat tail. This distribution is unstable to anomalous cyclotron resonance in a certain velocity space, resulting in thermalization and pitch-angle scattering of the electrons and consequent losses of the electron parallel velocity. A bump-on-tail distribution results, and a new instability develops which results in a flattening of the bump-on-tail. This instability can ramp the parallel velocity around a critical value. Only a small part of the electrons can be accelerated further, albeit very slowly, and they are simultaneously thermalized.

Wang, Y.-D.; Cai, H.-J.

1985-10-01

228

Cyclotron-based of plant gravisensing  

NASA Astrophysics Data System (ADS)

Roots exhibit positive gravitropism they grow in the direction of a gravitational vector while shoots respond negatively and grow opposite to a gravitational vector We first demonstrated the inversion of roots gravitropism from positive to negative one under gravistimulation in the weak combined magnetic field WCMF consisted of permanent magnetic field PMF with the magnitude of order of 50 mu T and altering magnetic field AMF with the 6 mu T magnitude and a frequency of 32 Hz It was found that the effect of inversion has a resonance nature It means that in the interval of frequencies 1-45 Hz inversion of root gravitropism occurs only at frequency 32 Hz 2-3-day old cress seedlings were gravistimulated in moist chambers which are placed in mu -metal shields Inside mu -metal shields combined magnetic fields have been created The magnitude of magnetic fields was measured by a flux-gate magnetometer Experiments were performed in darkness at temperature 20 pm 1 0 C We measured the divergence angle of a growing root from its horizontal position After 1 h of gravistimulation in the WCMF we observed negative gravitropism of cress roots i e they grow in the opposite direction to a gravitational vector Frequency of 32 Hz for the magnitude of the PMF applied formally corresponds to cyclotron frequency of Ca 2 ions This indicates possible participation of calcium ions in root gravitropism There are many evidences of resonance effects of the WCMF on the biological processes that involve Ca 2 but the nature of

Kordyum, E.; Kalinina, Ia.; Bogatina, N.; Kondrachuk, A.

229

Electron cyclotron resonance charge breeder ion source simulation by MCBC and GEM  

SciTech Connect

Numerical simulation results by the GEM and MCBC codes are presented, along with a comparison with experiments for beam capture dynamics and parameter studies of charge state distribution (CSD) of electron cyclotron resonance charge breeder ion sources. First, steady state plasma profiles are presented by GEM with respect to key experimental parameters such as rf power and gas pressure. As rf power increases, electron density increases by a small amount and electron energy by a large amount. The central electrostatic potential dip also increased. Next, MCBC is used to trace injected beam ions to obtain beam capture profiles. Using the captured ion profiles, GEM obtains a CSD of beam ions. As backscattering can be significant, capturing the ions near the center of the device enhances the CSD. The effect of rf power on the beam CSD is mainly due to different steady states plasmas. Example cases are presented assuming that the beam ions are small enough not to affect the plasma.

Kim, J. S.; Zhao, L.; Cluggish, B. P.; Bogatu, I. N.; Pardo, R. [FAR-TECH, Inc., 3550 General Atomics Court 15-155, San Diego, California 92121 (United States); Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2008-02-15

230

Development of Electron Cyclotron Resonance Ion Source for Synthesis of Endohedral Metallofullerenes  

NASA Astrophysics Data System (ADS)

A new electron cyclotron resonance ion source (ECRIS) has been constructed for synthesis of endohedral metallofullerenes. The main purpose of the ion source is to produce new biological and medical materials. The design is based on ECRIS for production of multicharged ion beams with a traditional minimum-B magnetic field. An 8-10 GHz traveling wave tube (TWT) amplifier and a 2.45 GHz magnetron have been applied as microwave sources. Fullerene and metal vapor are introduced with a filament heating micro-oven and an induction heating oven, respectively. In preliminary ion-extraction test, Ar+ is 54 ?A. Many broken fullerenes such as C58 and C56 are observed in fullerene ion beams.

Tanaka, K.; Muramatsu, M.; Uchida, T.; Biri, S.; Asaji, T.; Shima, K.; Hanajiri, T.; Kitagawa, A.; Kato, Y.; Yoshida, Y.

2008-11-01

231

SPIE Medical Imaging Medical Imaging  

E-print Network

) Center Department of Radiology Georgetown University SPIE Medical Imaging 2006 2 Main Themes · Describe the major modalities in radiology (medical imaging) · Essential Physics and Engineering · Strengths Medical Imaging 2006 14 Skeletal MRI Scan of Head and Neck Region cpmcnet.columbia.edu/dept/radiology

Miga, Michael I.

232

Development of a fast scintillator based beam phase measurement system for compact superconducting cyclotrons  

SciTech Connect

In an isochronous cyclotron, measurements of central phase of the ion beam with respect to rf and the phase width provide a way to tune the cyclotron for maximum energy gain per turn and efficient extraction. We report here the development of a phase measurement system and the measurements carried out at the Variable Energy Cyclotron Centre's (VECC's) K= 500 superconducting cyclotron. The technique comprises detecting prompt {gamma}-rays resulting from the interaction of cyclotron ion beam with an aluminium target mounted on a radial probe in coincidence with cyclotron rf. An assembly comprising a fast scintillator and a liquid light-guide inserted inside the cyclotron was used to detect the {gamma}-rays and to transfer the light signal outside the cyclotron where a matching photo-multiplier tube was used for light to electrical signal conversion. The typical beam intensity for this measurement was a few times 10{sup 11} pps.

Bhattacharjee, Tanushyam; Kanti Dey, Malay; Dhara, Partha; Roy, Suvodeep; Debnath, Jayanta; Balakrishna Bhole, Rajendra; Dutta, Atanu; Pradhan, Jedidiah; Pal, Sarbajit; Pal, Gautam; Roy, Amitava; Chakrabarti, Alok [Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata 700064 (India)

2013-05-15

233

ICRF (Ion Cyclotron Range of Frequency) Enhancement of Fusion Reactivity in the Presence of alpha Particles.  

National Technical Information Service (NTIS)

Absorption of ICRF (ion cyclotron range of frequency) waves by alpha particles and fusion reactivity enhancement due to the ICRF induced ion tail are investigated. The rate of linear absorption by alpha particles increases with the cyclotron harmonic numb...

M. Yamagiwa, T. Takizuka

1988-01-01

234

Design and construction of a cyclotron capable of accelerating protons to 2 MeV  

E-print Network

This thesis describes the design and construction of a cyclotron capable of accelerating protons to 2 MeV. A cyclotron is a charged particle accelerator that uses a magnetic field to confine particles to a spiral flight ...

Dewan, Leslie

2007-01-01

235

Radially Localized Measurements of Superthermal Electrons Using Oblique Electron Cyclotron Emission  

E-print Network

Radially Localized Measurements of Superthermal Electrons Using Oblique Electron Cyclotron Emission Electron Cyclotron Emission from superthermal electrons can be imposed by observation of emission upshifted diagnostic has been proposed and operated to make radially localized measurements of superthermal electrons

236

Simultaneous observations of electrostatic oxygen cyclotron waves and ion conics  

NASA Technical Reports Server (NTRS)

A sounding rocket launched to 927 km apogee during an auroral substorm encountered regions of large quasi-static electric fields (not greater than 400 mV/m), ion conics (up to 700 eV maximum observed energy), and fluctuating electric fields near the oxygen cyclotron frequency. Since the fluctuating electric fields frequently exhibited spectral peaks just above the local oxygen cyclotron frequency, and since the fluctuating electric fields were linearly polarized, they are positively identified as electrostatic oxygen cyclotron waves (EOCW). The maximum amplitude of the EOCW was about 5 mV/m rms. The EOCW closely correlated with the presence of ion conics. Because of the relatively low amplitude of the EOCW and their relatively low coherence, it cannot be concluded that they are solely responsible for the production of the ion conics.

Kintner, P. M.; Scales, W.; Vago, J.; Arnoldy, R.; Garbe, G.; Moore, T.

1989-01-01

237

The electron-cyclotron maser for astrophysical application  

NASA Astrophysics Data System (ADS)

The electron-cyclotron maser is a process that generates coherent radiation from plasma. In the last two decades, it has gained increasing attention as a dominant mechanism of producing high-power radiation in natural high-temperature magnetized plasmas. Originally proposed as a somewhat exotic idea and subsequently applied to include non-relativistic plasmas, the electron-cyclotron maser was considered as an alternative to turbulent though coherent wave-wave interaction which results in radio emission. However, when it was recognized that weak relativistic corrections had to be taken into account in the radiation process, the importance of the electron-cyclotron maser rose to the recognition it deserves. Here we review the theory and application of the electron-cyclotron maser to the directly accessible plasmas in our immediate terrestrial and planetary environments. In situ access to the radiating plasmas has turned out to be crucial in identifying the conditions under which the electron-cyclotron maser mechanism is working. Under extreme astrophysical conditions, radiation from plasmas may provide a major energy loss; however, for generating the powerful radiation in which the electron-cyclotron maser mechanism is capable, the plasma must be in a state where release of susceptible amounts of energy in the form of radiation is favorable. Such conditions are realized when the plasma is unable to digest the available free energy that is imposed from outside and stored in its particle distribution. The lack of dissipative processes is a common property of collisionless plasmas. When, in addition, the plasma density becomes so low that the amount of free energy per particle is large, direct emission becomes favorable. This can be expressed as negative absorption of the plasma which, like in conventional masers, leads to coherent emission even though no quantum correlations are involved. The physical basis of this formal analogy between a quantum maser and the electron-cyclotron maser is that in the electron-cyclotron maser the free-space radiation modes can be amplified directly. Several models have been proposed for such a process. The most famous one is the so-called loss-cone maser. However, as argued in this review, the loss-cone maser is rather inefficient. Available in situ measurements indicate that the loss-cone maser plays only a minor role. Instead, the main source for any strong electron-cyclotron maser is found in the presence of a magnetic-field-aligned electric potential drop which has several effects: (1) it dilutes the local plasma to such an extent that the plasma enters the regime in which the electron-cyclotron maser becomes effective; (2) it generates energetic relativistic electron beams and field-aligned currents; (3) it deforms, together with the magnetic mirror force, the electron distribution function, thereby mimicking a high energy level sufficiently far above the Maxwellian ground state of an equilibrium plasma; (4) it favors emission in the free-space RX mode in a direction roughly perpendicular to the ambient magnetic field; (5) this emission is the most intense, since it implies the coherent resonant contribution of a maximum number of electrons in the distribution function to the radiation (i.e., to the generation of negative absorption); (6) it generates a large number of electron holes via the two-stream instability, and ion holes via the current-driven ion-acoustic instability which manifest themselves as subtle fine structures moving across the radiation spectrum and being typical for the electron-cyclotron maser emission process. These fine structures can thus be taken as the ultimate identifier of the electron-cyclotron maser. The auroral kilometric radiation of Earth is taken here as the paradigm for other manifestations of intense radio emissions such as the radiation from other planets in the solar system, from exoplanets, the Sun and other astrophysical objects.

Treumann, Rudolf A.

2006-08-01

238

Spectra and Neutron Dosimetry Inside a PET Cyclotron Vault Room  

NASA Astrophysics Data System (ADS)

The neutron field around a PET cyclotron was investigated during 18F radioisotope production with an 18 MeV proton beam. Pairs of thermoluminescent dosemeters, TLD600 and TLD700, were used as thermal neutron detector inside a Bonner Spheres Spectrometer to measure the neutron spectra at three different positions inside the cyclotron's vault room. Neutron spectra were also determined by Monte Carlo calculations. The hardest spectrum was observed in front of cyclotron target and the softest was noticed at the antipode of target. Neutron doses derived from the measured spectra vary between 11 and 377 mSv/?A-h of proton integrated current, Doses were also measured with a single-moderator remmeter, with an active thermal neutron detector, whose response in affected by the radiation field in the vault room.

Vega-Carrillo, Héctor René; Méndez, Roberto; Iñiguez, María Pilar; Martí-Climent, Joseph; Peñuelas, Iván; Barquero, Raquel

2006-09-01

239

Spectra and Neutron Dosimetry Inside a PET Cyclotron Vault Room  

SciTech Connect

The neutron field around a PET cyclotron was investigated during 18F radioisotope production with an 18 MeV proton beam. Pairs of thermoluminescent dosemeters, TLD600 and TLD700, were used as thermal neutron detector inside a Bonner Spheres Spectrometer to measure the neutron spectra at three different positions inside the cyclotron's vault room. Neutron spectra were also determined by Monte Carlo calculations. The hardest spectrum was observed in front of cyclotron target and the softest was noticed at the antipode of target. Neutron doses derived from the measured spectra vary between 11 and 377 mSv/{mu}A-h of proton integrated current, Doses were also measured with a single-moderator remmeter, with an active thermal neutron detector, whose response in affected by the radiation field in the vault room.

Vega-Carrillo, Hector Rene [Unidades Academicas: Estudios Nucleares e Ing. Electrica. Universidad Autonoma de Zacatecas, A.P. 336, 98000 Zacatecas, Zac. Mexico (Mexico); Mendez, Roberto [Universidad Europea Miguel de Cervantes, Valladolid (Spain); Iniguez, Maria Pilar [Facultad de Ciencias de la Universidad de Valladolid, Valladolid (Spain); Marti-Climent, Joseph; Penuelas, Ivan [Servicio de Medicina Nuclear, Clinica Universitaria de la Universidad de Navarra (Spain); Barquero, Raquel [Hospital Universitario Rio Hortega, Valladolid (Spain)

2006-09-08

240

A Pilot Trial of Serial 18F-Fluorodeoxyglucose Positron Emission Tomography in Patients With Medically Inoperable Stage I Non-Small-Cell Lung Cancer Treated With Hypofractionated Stereotactic Body Radiotherapy  

SciTech Connect

Purpose: Routine assessment was made of tumor metabolic activity as measured by 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in Stage I non-small-cell lung cancer (NSCLC). This report describes PET correlates prospectively collected after stereotactic body radiotherapy (SBRT) for patients with medically inoperable NSCLC. Methods and Materials: 14 consecutive patients with medically inoperable Stage I NSCLC were enrolled. All patients received SBRT to 60-66 Gy in three fractions. Patients underwent serial planned FDG-PET/computed tomography fusion imaging before SBRT and at 2, 26, and 52 weeks after SBRT. Results: With median follow-up of 30.2 months, no patients experienced local failure. One patient developed regional failure, 1 developed distant failure, and 1 developed a second primary. The median tumor maximum standardized uptake value (SUV{sub max}) before SBRT was 8.70. The median SUV{sub max} values at 2, 26, and 52 weeks after SBRT were 6.04, 2.80, and 3.58, respectively. Patients with low pre-SBRT SUV were more likely to experience initial 2-week rises in SUV, whereas patients with high pre-SBRT SUV commonly had SUV declines 2 weeks after treatment (p = 0.036). Six of 13 patients had primary tumor SUV{sub max} >3.5 at 12 months after SBRT but remained without evidence of local disease failure on further follow-up. Conclusions: A substantial proportion of patients may have moderately elevated FDG-PET SUV{sub max} at 12 months without evidence of local failure on further follow-up. Thus, slightly elevated PET SUV{sub max} should not be considered a surrogate for local treatment failure. Our data do not support routine serial FDG-PET/computed tomography for follow-up of patients receiving SBRT for Stage I NSCLC.

Henderson, Mark A., E-mail: mahender@iupui.ed [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN (United States); Hoopes, David J. [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN (United States); Department of Radiation Oncology, Wright-Patterson Medical Center, Wright-Patterson Air Force Base, OH (United States); Fletcher, James W.; Lin, P.-F.; Tann, Mark [Department of Nuclear Medicine, Indiana University School of Medicine, Indianapolis, IN (United States); Yiannoutsos, Constantin T. [Division of Biostatistics, Indiana University School of Medicine, Indianapolis, IN (United States); Williams, Mark D. [Pulmonary Division, Richard L. Roudebush Veterans Administration Medical Center, Indianapolis, IN (United States); Fakiris, Achilles J. [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN (United States); McGarry, Ronald C. [Department of Radiation Medicine, University of Kentucky, Lexington, KY (United States); Timmerman, Robert D. [Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX (United States)

2010-03-01

241

Numerical simulation of electron cyclotron current drive characteristics on EAST  

NASA Astrophysics Data System (ADS)

Electron cyclotron current drive (ECCD) will be applied in the EAST tokamak during its the new campaign. In order to provide theoretical predictions for relevant physical experiments, some numerical simulations of ECCD with the parameters of EAST have been carried out by using TORAY-GA code based on the understanding of ECCD mechanisms. ECCD efficiencies achieved in different plasma and electron cyclotron (EC) wave parameters are given. The dependences of ECCD characteristics on EC wave injection angle, toroidal magnetic field, plasma density, and temperature are presented and discussed.

Wei, Wei; Ding, Bo-Jiang; Zhang, Xin-Jun; Wang, Xiao-Jie; Li, Miao-Hui; Kong, Er-Hua; Zhang, Lei

2014-05-01

242

Residual radioactivity in a cyclotron and its surroundings.  

PubMed

Neutron-induced gamma-ray-emitting radionuclides in components and surroundings of the University of Colorado 1.3-m sector-focusing cyclotron have been measured with Ge(Li) and HPGe detectors. These measurements were made before decommissioning of the cyclotron and before approving release of the accelerator components and building space for other uses. In addition to the activities expected from previous published work, 13.3-y 152Eu and 8.6-y 154Eu were found in the concrete shielding with specific activities of tens of becquerels per kilogram (a few nanocuries per kilogram). PMID:3744833

Phillips, A B; Prull, D E; Ristinen, R A; Kraushaar, J J

1986-09-01

243

Backward Wave Cyclotron-Maser Emission in the Auroral Magnetosphere  

NASA Astrophysics Data System (ADS)

In this Letter, we present theory and particle-in-cell simulations describing cyclotron radio emission from Earth's auroral region and similar phenomena in other astrophysical environments. In particular, we find that the radiation, generated by a down-going electron horseshoe distribution is due to a backward-wave cyclotron-maser emission process. The backward wave nature of the radiation contributes to upward refraction of the radiation that is also enhanced by a density inhomogeneity. We also show that the radiation is preferentially amplified along the auroral oval rather than transversely. The results are in agreement with recent Cluster observations.

Speirs, D. C.; Bingham, R.; Cairns, R. A.; Vorgul, I.; Kellett, B. J.; Phelps, A. D. R.; Ronald, K.

2014-10-01

244

ELECTRON CYCLOTRON CURRENT DRIVE EFFICIENCY IN GENERAL TOKAMAK GEOMETRY  

SciTech Connect

Green's-function techniques are used to calculate electron cyclotron current drive (ECCD) efficiency in general tokamak geometry in the low-collisionality regime. Fully relativistic electron dynamics is employed in the theoretical formulation. The high-velocity collision model is used to model Coulomb collisions and a simplified quasi-linear rf diffusion operator describes wave-particle interactions. The approximate analytic solutions which are benchmarked with a widely used ECCD model, facilitate time-dependent simulations of tokamak operational scenarios using the non-inductive current drive of electron cyclotron waves.

LIN-LUI,Y.R; CHAN,V.S; PRATER,R

2003-03-01

245

A 600 MeV cyclotron for radioactive beam production  

SciTech Connect

The magnetic field design for a 600 MeV proton cyclotron is described. The cyclotron has a single stage, a normal conducting magnet coil and a 9.8 m outside yoke diameter. It has 8 sectors, with a transition to 4 sectors in the center region. The magnetic field design was done using 1958 Harwell rectangular ridge system measurements and was compared with recent 3-dimensional field calculations with the program TOSCA at NSCL. The center region 4--8 sector transition focussing was also checked with TOSCA.

Clark, D.J.

1993-05-17

246

Cyclotron harmonics in opacities of isolated neutron star atmospheres  

E-print Network

Some of X-ray dim isolated neutron stars (XDINS) and central compact objects in supernova remnants (CCO) show absorption features in their thermal soft X-ray spectra. There have been suggestions in the literature that these features could be due to the periodic peaks in free-free absorption opacities, caused either by Landau quantization of electron motion in magnetic fields B10^{13} G. I review the physics behind cyclotron quantum harmonics in free-free photoabsorption, discuss different approximations for their calculation, and explain why the ion cyclotron harmonics (beyond the fundamental) cannot be observed.

Potekhin, A Y

2010-01-01

247

Two aspects of the K500 cyclotron project  

E-print Network

beamline. Page 9 ll 16 18 19 22 24 28 30 31 33 35 38 50 Page Fig. 19. Elevation viev of the vertical portion of the ECRIS to K500 cyclotron beamline. Fig. 20. The fringe-field of the K500 cyclotron measured approximately 1. 2 m above... foz detection of the light) viewing a reflective glass scale (18). The photosensors vere NAN0-S[(AN [19) fiber optic scanners model S2005-3 with a rated resolution of + 0. 001 in. and a -6 reproducibility of + 5 x 10 . The glass scale was 16. 1 in...

Van Baalen, Aaron Chase

2012-06-07

248

A compact cost-effective beamline for a PET Cyclotron  

NASA Astrophysics Data System (ADS)

Most commercial PET Cyclotrons have targets mounted on or near the main cyclotron vacuum chamber. There is often little or no system capability for centering or focusing the extracted beam on target to achieve maximum production. This paper describes the ion-optics, design and development of a compact cost-effective beamline comprised of low activation and radiation resistant materials. The beamline, complete with suitable diagnostic devices, permits the extracted proton beam to be centered ( X- Y steering magnet), and focused (quadrupole doublet) on target eliminating unnecessary beamspill and ensuring high production.

Dehnel, M. P.; Jackle, P.; Roeder, M.; Stewart, T.; Theroux, J.; Brasile, J. P.; Sirot, P.; Buckley, K. R.; Bedue, M.

2007-08-01

249

The relation between cyclotron heating and energetic particles on open coronal field lines  

Microsoft Academic Search

Cyclotron resonance with high-frequency Alfvén waves has been proposed as an ion heating mechanism for producing high-speed winds and large ion temperatures in coronal holes. In the simplest version of the model (cyclotron sweep model), the waves propagate without interacting until they hit a resonance with the plasma ions at distance, where the ion cyclotron frequency becomes comparable to the

T. Laitinen

2001-01-01

250

Emergency Medical Service (EMS): Rotorcraft Technology Workshop  

NASA Technical Reports Server (NTRS)

A lead organization on the national level should be designated to establish concepts, locations, and the number of shock trauma air medical services. Medical specialists desire a vehicle which incorporates advances in medical technology trends in health care. Key technology needs for the emergency medical services helicopter of the future include the riding quality of fixed wing aircraft (reduced noise and vibration), no tail rotor, small rotor, small rotor diameter, improved visibility, crashworthy vehicle, IFR capability, more affordability high reliability, fuel efficient, and specialized cabins to hold medical/diagnostic and communications equipment. Approaches to a national emergency medical service are discussed.

Bauchspies, J. S.; Adams, R. J.

1981-01-01

251

Medical Assistants  

NSDL National Science Digital Library

For a concise summary of the medical assistant profession the Medical Assistants entry in the Bureau of Labor Statistics' Occupational Outlook Handbook is must read. The site covers topics ranging from the nature of the profession, working conditions, earnings, and more. The section on training, qualifications and advancement will be of special interest to medical assistant faculty and students. The section on sources of addition information will also be a good launching point for anyone seeking additional online resources.

2006-11-01

252

Accelerator science in medical physics  

PubMed Central

The use of cyclotrons and synchrotrons to accelerate charged particles in hospital settings for the purpose of cancer therapy is increasing. Consequently, there is a growing demand from medical physicists, radiographers, physicians and oncologists for articles that explain the basic physical concepts of these technologies. There are unique advantages and disadvantages to all methods of acceleration. Several promising alternative methods of accelerating particles also have to be considered since they will become increasingly available with time; however, there are still many technical problems with these that require solving. This article serves as an introduction to this complex area of physics, and will be of benefit to those engaged in cancer therapy, or who intend to acquire such technologies in the future. PMID:22374548

Peach, K; Wilson, P; Jones, B

2011-01-01

253

Medical confidence.  

PubMed Central

If medical confidentiality is not observed patients may well be reluctant to disclose information to their doctors or even to seek medical advice. Therefore, argues the author, it is of the utmost importance that doctors strive to protect medical confidentiality, particularly now when it is under threat not only in this country but also overseas. The profession must cease to regard ethical issues to do with confidentiality, and indeed to do with all areas of medical practice, as abstract phenomena requiring no justification. If it does not then it will come under increasing and justified criticism from the community it serves. PMID:3981576

Havard, J

1985-01-01

254

Electrostatic ion cyclotron and ion plasma waves in a symmetric pair-ion plasma cylinder.  

PubMed

Complicated wave behavior observed in the cylindrical pair-ion (fullerene) experiments by Oohara and co-workers are now identified to be low harmonic ion cyclotron waves combined with ion plasma oscillations inherent to kinetic theory. The electrostatic dispersion equation derived is based on an approximation for the current from the exact solutions of the characteristic cylindrical geometry form of the Vlasov plasma equation in a uniform magnetized plasma cylinder surrounded by a larger metal boundary outside a vacuum gap, which thus differs from that in unbounded plasmas. Positive and negative ions, differing only in the sign of their charge, respond to a potential in the same time scale and cooperate to reflect the enhanced kinetic orbital behaviors to the macroscopic propagation characteristics. In addition, the experimental value of the Larmor radius (comparable to the discharge radius but small enough to make the analytic approximation useful) makes higher harmonic ion cyclotron effects both observable and calculable with the appropriate approximation for the kinetic theory. PMID:24679299

Kono, M; Vranjes, J; Batool, N

2014-03-14

255

Performance of the beam chamber vacuum system of K = 500 cyclotron at Variable Energy Cyclotron Centre Kolkata  

NASA Astrophysics Data System (ADS)

The beam chamber of Variable Energy Cyclotron Centre, Kolkata's K = 500 superconducting cyclotron is pumped by liquid helium cooled cryopanel with liquid nitrogen cooled radiation shield. Performance of the vacuum system was evaluated by cooling the cryopanel assembly with liquid nitrogen and liquid helium. Direct measurement of beam chamber pressure is quite difficult because of space restrictions and the presence of high magnetic field. Pressure gauges were placed away from the beam chamber. The beam chamber pressure was evaluated using a Monte Carlo simulation software for vacuum system and compared with measurements. The details of the vacuum system, measurements, and estimation of pressure of the beam chamber are described in this paper.

Pal, Gautam; DuttaGupta, Anjan; Chakrabarti, Alok

2014-07-01

256

Non-linear effects in electron cyclotron current drive applied for the stabilization of neoclassical tearing modes  

NASA Astrophysics Data System (ADS)

Due to the smallness of the volumes associated with the flux surfaces around the O-point of a magnetic island, the electron cyclotron power density applied inside the island for the stabilization of neoclassical tearing modes (NTMs) can exceed the threshold for non-linear effects as derived previously by Harvey et al (1989 Phys. Rev. Lett. 62 426). We study the non-linear electron cyclotron current drive (ECCD) efficiency through bounce-averaged, quasi-linear Fokker-Planck calculations in the magnetic geometry as created by the islands. The calculations are performed for the parameters of a typical NTM stabilization experiment on ASDEX Upgrade. A particular feature of these experiments is that the rays of the EC wave beam propagate tangential to the flux surfaces in the power deposition region. The calculations show significant non-linear effects on the ECCD efficiency, when the ECCD power is increased from its experimental value of 1 MW to a larger value of 4 MW. The nonlinear effects are largest in the case of locked islands or when the magnetic island rotation period is longer than the collisional time scale. The non-linear effects result in an overall reduction of the current drive efficiency for this case with absorption of the EC power on the low-field side of the electron cyclotron resonance layer. As a consequence of the non-linear effects, also the stabilizing effect of the ECCD on the island is reduced from linear expectations.

Ayten, B.; Westerhof, E.; the ASDEX Upgrade Team

2014-07-01

257

Cyclotron Resonance of Electrons Trapped in a Microwave Cavity  

ERIC Educational Resources Information Center

Describes an experiment in which the free-electron cyclotron resonance of electrons trapped in a microwave cavity by a Penning trap is observed. The experiment constitutes an attractive alternative to one of the Gardner-Purcell variety. (Author/GS)

Elmore, W. C.

1975-01-01

258

Particle behaviour in an electron cyclotron resonance plasma etch tool  

Microsoft Academic Search

Sources of particles in a closed-coupled electron cyclotron resonance plasma source used for polysilicon etch included flaking of a residual film deposited on chamber surfaces and shedding of material from the electrostatic wafer chuck. A large, episodic increase in the number of particles added to a wafer in a clean system is observed more frequently for a plasma-on than for

M. G. Blain; G. D. Tipton; W. M. Holber; G. S. Selwyn; P. L. Westerfield; K. L. Maxwell

1994-01-01

259

Electron-cyclotron-heating experiments in tokamaks and stellarators  

SciTech Connect

This paper reviews the application of high-frequency microwave radiation to plasma heating near the electron-cyclotron frequency in tokamaks and stellarators. Successful plasma heating by microwave power has been demonstrated in numerous experiments. Predicted future technological developments and current theoretical understanding suggest that a vigorous program in plasma heating will continue to yield promising results.

England, A.C.

1983-01-01

260

Numerical simulation of unconstrained cyclotron resonant maser emission  

NASA Astrophysics Data System (ADS)

When a mainly rectilinear electron beam is subject to significant magnetic compression, conservation of magnetic moment results in the formation of a horseshoe shaped velocity distribution. It has been shown that such a distribution is unstable to cyclotron emission and may be responsible for the generation of Auroral Kilometric Radiation (AKR) -an intense rf emission sourced at high altitudes in the terrestrial auroral magnetosphere. PiC code simulations have been undertaken to investigate the dynamics of the cyclotron emission process in the absence of cavity boundaries with particular consideration of the spatial growth rate, spectral output and rf conversion efficiency. Computations reveal that a well-defined cyclotron emission process occurs albeit with a low spatial growth rate compared to waveguide bounded simulations. The rf output is near perpendicular to the electron beam with a slight backward-wave character reflected in the spectral output with a well defined peak at 2.68GHz, just below the relativistic electron cyclotron frequency. The corresponding rf conversion efficiency of 1.1% is comparable to waveguide bounded simulations and consistent with the predictions of kinetic theory that suggest efficient, spectrally well defined radiation emission can be obtained from an electron horseshoe distribution in the absence of radiation boundaries.

Speirs, D. C.; Gillespie, K. M.; Ronald, K.; McConville, S. L.; Phelps, A. D. R.; Cross, A. W.; Bingham, R.; Kellett, B. J.; Cairns, R. A.; Vorgul, I.

2014-05-01

261

Ion-cyclotron-resonance-heated conics: Theory and observations  

Microsoft Academic Search

A general theoretical treatment of energetic oxygen ion conic formation through cyclotron resonance with magnetospheric electromagnetic plasma turbulence is presented. With suitable assumptions, there exists a similarity regime in which the process may be profitably characterized by two parameters corresponding roughly to the velocity scale and pitch angle of the ion distribution. These may be independently determined from the wave

G. B. Crew; Tom Chang; J. M. Retterer; W.K. Peterson; D. A. Gurnett; R. L. Huff

1990-01-01

262

CONSIDERATIONS OF CYCLOTRON RESONANCE BREAKDOWN IN THE TOROIDAL OCTUPOLE  

E-print Network

into the octupole from an ex- terna1 gun, plasma can be produced within the field by filling the toroidal cavity Sept., 1967 University of Wisconsin Thermonuclear Plasma Studies PLP 142 #12;CONSIDERATIONS OF CYCLOTRON RESONANCE BREAKDOWN IN THE TOROIDAL OCTUPOLE INTRODUCTION 2 As an alternative to injecting plasma

Sprott, Julien Clinton

263

Improvements in the Michigan State University Cyclotron RF System  

Microsoft Academic Search

A new all solid state dee voltage amplitude regulator has been built for the MSU Cyclotron. It should lead to a factor of two improvement in the energy resolution of the external beam with a consequent increase in the ratio of beam-on-target to internal beam for most experiments. The RF drive to the final amplifier is regulated at a 10

W. P. Johnson; P. K. Sigg

1969-01-01

264

Resonant plasma heating below the cyclotron frequencya... Roscoe Whiteb)  

E-print Network

of Alfve�n waves, particles to speeds comparable to the Alfve�n velocity in a few hundred cyclotron periods consisting of a number of modes. This phenomenon may have relevance for the heating of ions in the solar of Physics. DOI: 10.1063/1.1445180 I. INTRODUCTION Resonant heating of particles in a magnetic field

Lin, Zhihong

265

Electron-cyclotron resonance heating and current drive.  

National Technical Information Service (NTIS)

A brief summary of the theory and experiments on electron-cyclotron heating and current drive is presented. The general relativistic formulation of wave propagation and linear absorption is considered in some detail. The O-mode and the X-mode for normal a...

1992-01-01

266

Dynamic effects on cyclotron scattering in pulsar accretion columns  

NASA Technical Reports Server (NTRS)

A resonant scattering model for photon reprocessing in a pulsar accretion column is presented. The accretion column is optically thin to Thomson scattering and optically thick to resonant scattering at the cyclotron frequency. Radiation from the neutron star surface propagates freely through the column until the photon energy equals the local cyclotron frequency, at which point the radiation is scattered, much of it back toward the star. The radiation pressure in this regime is insufficient to stop the infall. Some of the scattered radiation heats the stellar surface around the base of the column, which adds a softer component to the spectrum. The partial blocking by the accretion column of X-rays from the surface produces a fan beam emission pattern. X-rays above the surface cyclotron frequency freely escape and are characterized by a pencil beam. Gravitational light bending produces a pencil beam pattern of column-scattered radiation in the antipodal direction, resulting in a strongly angle-dependent cyclotron feature.

Brainerd, J. J.; Meszaros, P.

1991-01-01

267

Anticipated Radiological Hazard in the AIC-144 Cyclotron.  

National Technical Information Service (NTIS)

A new AIC-144 cyclotron is being built within the radiation shields of the old U-120 accelerator. In order to evaluate the radiological hazard, the radiation protection problems were discussed and dose equivalent rates outside shields computed for the hig...

T. Niewiadomski

1981-01-01

268

Radiation effects test facility at the Indiana University Cyclotron Facility  

Microsoft Academic Search

The beam line end station, associated instrumentation and dosimetry used at the Indiana University Cyclotron Facility for radiation effects research and testing with up to 200 MeV protons are described. Access to beam for radiation effects studies is greatly enhanced by the capability to share beam with other users on a millisecond time scale. Use of shared beam mandates that

C. C. Foster; S. L. Casey; A. L. Johnson; P. Miesle; N. Sifri; A. H. Skees; K. M. Murray

1997-01-01

269

Cyclotron waves in a non-neutral plasma column  

SciTech Connect

A kinetic theory of linear electrostatic plasma waves with frequencies near the cyclotron frequency {Omega}{sub c{sub s}} of a given plasma species s is developed for a multispecies non-neutral plasma column with general radial density and electric field profiles. Terms in the perturbed distribution function up to O(1/{Omega}{sub c{sub s}{sup 2}}) are kept, as are the effects of finite cyclotron radius r{sub c} up to O(r{sub c}{sup 2}). At this order, the equilibrium distribution is not Maxwellian if the plasma temperature or rotation frequency is not uniform. For r{sub c}{yields}0, the theory reproduces cold-fluid theory and predicts surface cyclotron waves propagating azimuthally. For finite r{sub c}, the wave equation predicts that the surface wave couples to radially and azimuthally propagating Bernstein waves, at locations where the wave frequency equals the local upper hybrid frequency. The equation also predicts a second set of Bernstein waves that do not couple to the surface wave, and therefore have no effect on the external potential. The wave equation is solved both numerically and analytically in the WKB approximation, and analytic dispersion relations for the waves are obtained. The theory predicts that both types of Bernstein wave are damped at resonances, which are locations where the Doppler-shifted wave frequency matches the local cyclotron frequency as seen in the rotating frame.

Dubin, Daniel H. E. [Department of Physics, University of California at San Diego, La Jolla, California 92093 (United States)

2013-04-15

270

Ion cyclotron range of frequencies antenna design for R tokamak  

Microsoft Academic Search

The ion cyclotron range of frequencies antenna design for the R tokamak (a proposal by the Institute of Plasma Physics, Nagoya University) is described. The design involves three types of antennas: a standard loop antenna, a panel heater antenna, and a waveguide antenna for ion Bernstein wave heating (IBWH). The standard loop antenna is made of aluminum alloy and has

E. Kako; R. Ando; M. Ichimura; Y. Ogawa; T. Amano; T. Watari

1987-01-01

271

Design Characteristics of a Cyclotron for Producing Radioisotopes.  

National Technical Information Service (NTIS)

A description is given of the construction and parts design of a cyclotron for producing radioisotopes in automated target devices and for accelerating protons to an energy of 25 MeV. 8 references, 8 figures, 2 tables. (ERA citation 08:012827)

N. V. Akulova, P. V. Bogdanov, I. F. Malyshev, V. Y. Moiseev, V. N. Moshkin

1981-01-01

272

Cyclotron masses, electronic specific heat, and Fermi velocities in copper  

Microsoft Academic Search

The electronic density of states on the Fermi surface of copper has been calculated starting from the cyclotron masses of Coleridge and Watts, and those of Koch, Stradling, and Kip. The comparison of the results with the experimental value of the electronic specific heat indicates that the first set of masses is more consistent with the current ideas of the

B. Bosacchi; P. Franzosi

1975-01-01

273

Proposal for a Sector-Focusing Synchro-Cyclotron  

Microsoft Academic Search

A modification is proposed for the Uppsala 185 MeV Synchro-cyclotron to obtain a high intensity beam of different particles. By introducing sectors, a radially increasing magnetic field can be used. The reduced bandwidth makes it possible to replace the present rotating condenser by an electronically tuned broadband system. Protons will be accelerated with decreasing and heavier particles with increasing frequencies.

S. Kullander; S. Holm; B. Johanason; A. Tidriks

1966-01-01

274

Medication reviews  

PubMed Central

Recent years have seen a formalization of medication review by pharmacists in all settings of care. This article describes the different types of medication review provided in primary care in the UK National Health Service (NHS), summarizes the evidence of effectiveness and considers how such reviews might develop in the future. Medication review is, at heart, a diagnostic intervention which aims to identify problems for action by the prescriber, the clinican conducting the review, the patient or all three but can also be regarded as an educational intervention to support patient knowledge and adherence. There is good evidence that medication review improves process outcomes of prescribing including reduced polypharmacy, use of more appropriate medicines formulation and more appropriate choice of medicine. When ‘harder’ outcome measures have been included, such as hospitalizations or mortality in elderly patients, available evidence indicates that whilst interventions could improve knowledge and adherence they did not reduce mortality or hospital admissions with one study showing an increase in hospital admissions. Robust health economic studies of medication reviews remain rare. However a review of cost-effectiveness analyses of medication reviews found no studies in which the cost of the intervention was greater than the benefit. The value of medication reviews is now generally accepted despite lack of robust research evidence consistently demonstrating cost or clinical effectiveness compared with traditional care. Medication reviews can be more effectively deployed in the future by targeting, multi-professional involvement and paying greater attention to medicines which could be safely stopped. PMID:22607195

Blenkinsopp, Alison; Bond, Christine; Raynor, David K

2012-01-01

275

VASIMR Simulation Studies of Auroral Ion Cyclotron Heating  

NASA Astrophysics Data System (ADS)

Plasma physics has found an increasing range of practical industrial applications, including the development of electric spacecraft propulsion systems. One of these systems, the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) engine, both applies and can be used to simulate several important physical processes occurring in the magnetosphere. These processes include the mechanisms involved in the ion acceleration and heating that occur in the Birkeland currents of an auroral arc system. Auroral current region processes that are simulated in VASIMR include lower hybrid heating, parallel electric field acceleration and ion cyclotron acceleration. This paper will focus on using a physics demonstration model VASIMR to study ion cyclotron heating (ICRH) similar to auroral zone processes. The production of upward moving `ion conics' and ion heating are significant features in auroral processes. It is believed that ion cyclotron heating plays a role in these processes, but laboratory simulation of these auroral effects is difficult owing to the fact that the ions involved only pass through the acceleration region once. In the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) we have successfully simulated these effects. The current configuration of the VASIMR uses a helicon antenna with up to 20 kW of power to generate plasma then uses an RF booster stage that uses left hand polarized slow mode waves launched from the high field side of the resonance. The current setup for the booster uses 2 to 4 MHz waves with up to 20 kW of power. This is similar to the ion cyclotron heating in tokamaks, but in the VASIMR the ions only pass through the resonance region once. The rapid absorption of ion cyclotron waves has been predicted in recent theoretical studies. These theoretical predictions have been confirmed with several independent measurements. The ion cyclotron resonance heating (ICRH) shows a substantial increase in ion velocity. Pitch angle distribution studies show that this increase takes place in the resonance region where the ion cyclotron frequency is equal to the frequency on the injected RF waves. Downstream of the resonance region the perpendicular velocity boost should be converted to axial flow velocity through the conservation of the first adiabatic invariant as the magnetic field decreases in the exhaust region of the VASIMR.

Brukardt, M.; Bering, E. A.; Chang-Diaz, F. R.; Squire, J. P.; Glover, T. W.; Jacobs0n, V. T.; McCaskill, G. E.; Cassady, L. D.; Bengtson, R. D.

2006-12-01

276

Cyclotron resonance study of quasiparticle mass and scattering rate in the hidden-order and superconducting phases of URu2Si2  

NASA Astrophysics Data System (ADS)

The observation of cyclotron resonance in ultraclean crystals of URu2Si2 [S. Tonegawa et al., Phys. Rev. Lett. 109, 036401 (2012), 10.1103/PhysRevLett.109.036401] provides another route besides quantum oscillations to the determination of the bulk electronic structure in the hidden-order phase. We report detailed analyses of the resonance lines, which fully resolve the cyclotron mass structure of the main Fermi surface sheets. A particular focus is given to the anomalous splitting of the sharpest resonance line near the [110] direction under in-plane magnetic-field rotation, which implies peculiar electronic structure in the hidden-order phase. The results under the field rotation from [110] toward [001] direction reveal that the splitting is a robust feature against field tilting from the basal plane. This is in sharp contrast to the reported frequency branch ? in the quantum oscillation experiments showing a three-fold splitting that disappears by a small field tilt, which can be explained by the magnetic breakdown between the large hole sphere and small electron pockets. Our analysis of the cyclotron resonance profiles reveals that the heavier branch of the split line has a larger scattering rate, providing evidence for the existence of hot-spot regions along the [110] direction. These results are consistent with the broken fourfold rotational symmetry in the hidden-order phase, which can modify the interband scattering in an asymmetric manner. We also extend our measurements down to 0.7 K, which results in the observation of cyclotron resonance in the superconducting state, where novel effects of vortex dynamics may enter. We find that the cyclotron mass undergoes no change in the superconducting state. In contrast, the quasiparticle scattering rate shows a rapid decrease below the vortex-lattice melting transition temperature, which supports the formation of quasiparticle Bloch state in the vortex lattice phase.

Tonegawa, S.; Hashimoto, K.; Ikada, K.; Tsuruhara, Y.; Lin, Y.-H.; Shishido, H.; Haga, Y.; Matsuda, T. D.; Yamamoto, E.; Onuki, Y.; Ikeda, H.; Matsuda, Y.; Shibauchi, T.

2013-12-01

277

Cyclotron resonance of single-valley Dirac fermions in nearly gapless HgTe quantum wells  

NASA Astrophysics Data System (ADS)

We report on Landau level spectroscopy studies of two HgTe quantum wells (QWs) near or at the critical well thickness, where the band gap vanishes. In magnetic fields up to B =16 T, oriented perpendicular to the QW plane, we observe a ?B dependence for the energy of the dominant cyclotron resonance (CR) transition characteristic of two-dimensional Dirac fermions. The dominant CR line exhibits either a single or double absorption line shape for the gapless or gapped QW. Using an effective Dirac model, we deduce the band velocity of single-valley Dirac fermions in gapless HgTe quantum wells, vF=6.4×105 m/s, and interpret the double absorption of the gapped QW as resulting from the addition of a small relativistic mass.

Ludwig, J.; Vasilyev, Yu. B.; Mikhailov, N. N.; Poumirol, J. M.; Jiang, Z.; Vafek, O.; Smirnov, D.

2014-06-01

278

Effect of turbulence on electron cyclotron current drive and heating in ITER  

E-print Network

Non-linear local electromagnetic gyrokinetic turbulence simulations of the ITER standard scenario H-mode are presented for the q=3/2 and q=2 surfaces. The turbulent transport is examined in regions of velocity space characteristic of electrons heated by electron cyclotron waves. Electromagnetic fluctuations and sub-dominant micro-tearing modes are found to contribute significantly to the transport of the accelerated electrons, even though they have only a small impact on the transport of the bulk species. The particle diffusivity for resonant passing electrons is found to be less than 0.15 m^2/s, and their heat conductivity is found to be less than 2 m^2/s. Implications for the broadening of the current drive and energy deposition in ITER are discussed.

Casson, F J; Angioni, C; Buchholz, R; Peeters, A G

2014-01-01

279

Magnetic field calculation for a 10 MeV positron emission tomography cyclotron  

SciTech Connect

The magnetic field calculation and correction for a 10 MeV positron emission tomography cyclotron is presented. 3D TOSCA analysis results are compared with the measured data, and the calculation error is used to calibrate the B-H curve to obtain a very precise finite element method estimator, which is used to predict the correction of the magnet pole for achieving the isochronous field. The isochronous field error is approximated with the effects of a set of standard patches. On the assumption that the effect of each small patch is proportional to its surface, the correction of the magnet pole is found by solving a system of equations using the least square scheme. The magnet shimming is performed and the measured magnetic field is found in good agreement with the prediction, with an error less than 2 G.

Chen Dezhi; Liu Kaifeng; Yang Jun; Li Dong; Qin Bin; Xiong Yongqian [State Key Lab of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Chen Zihao [Central Southern Electrical Power Design Institute, Wuhan 430071 (China)

2013-05-15

280

[Cyclotron resonance as a cause of biological effects of weak electric and magnetic fields?].  

PubMed

Even weak electric and magnetic fields have been found to cause interaction effects in vitro only within small frequency ranges. The existence of such "frequency windows" may be explained by a cyclotron resonance model which also takes the influence of the earth's magnetic field into consideration. In this paper analytical relations are developed which permit the determination of energy uptake and motion curve diameter. On the basis of this calculations it can be concluded that, giving consideration to interparticle interactions and the limitations of motion curve dimensions due to the limited dimensions of cells and cellular interspaces, energy uptake in vivo is many orders of magnitude below thermal energy, and can therefore be neglected. PMID:2164850

Leitgeb, N

1990-06-01

281

Cyclotron production of I-123: An evaluation of the nuclear reactions which produce this isotope  

NASA Technical Reports Server (NTRS)

The use of the various nuclear reactions is described by which I-123,a low radiation dose radiopharmaceutical, can be cyclotron-produced. Methods of directly producing I-123 and those which indirectly produce the radionuclide through the beta (+) decay of its nautral precursor, Xe-123. It is impossible to separate from the radioiodine contaminants, notably I-124, which occur in the direct method. Thus, it is preferable to produce pure I-123 from Xe-123 which is easily separated from the radioiodines. Among the characteristics of I-123 is the capability of reducing the patient dose in a thyroid uptake measurement to a very small percentage of that delivered by the more commonly used I-131.

Sodd, V. J.; Scholz, K. L.; Blue, J. W.; Wellman, H. N.

1970-01-01

282

Decontamination and decommissioning of the 60-inch Cyclotron facility at Argonne National Laboratory-East project final report  

Microsoft Academic Search

This final report of the decontamination and decommissioning (D&D) of the Argonne National Laboratory-East (ANL-E) 60'' Cyclotron Accelerator Facility contains descriptions and evaluations of activities performed, and results obtained in connection with the Cyclotron D&D Project. It provides the following information: Objective of the Cyclotron D&D Project; A brief history of the Cyclotron facility; Overall descriptions of the Cyclotron facility

E. Collins; J. Boyance; D. Tinnin; A. Williams

2001-01-01

283

Abortion - medical  

MedlinePLUS

... pregnancy resulted after a traumatic event such as rape or incest The woman may not wish to ... American College of Obstetricians and Gynecologists. Clinical management guidelines of obstetrician-gynecologists. Medical management of abortion. Obstet Gynecol . 2005 ...

284

Cardiac Medications  

MedlinePLUS

... fluid in the body. Vasodilators (Also known as Nitrates. Nitroglycerin tablets are a form of vasodilator.) Commonly ... include: Isosorbide dinitrate (Isordil) Nesiritide (Natrecor) Hydralazine (Apresoline) Nitrates Minoxidil What the Medication Does Relaxes blood vessels ...

285

Medication Math  

NSDL National Science Digital Library

Medication calculation needs to be completed accurately for proper patient treatment. In this section you will need to review and improve your medication math. Understanding math: Math and Culture Refresher: Take the amount of fluid in the bottle and times that by the dose ordered. Then divide this number by the amount of drug in the bottle. This will give you the volume of the drug that you need to administer. Diagram of formulas Math Formulas Math ...

Joey

2008-10-16

286

Medical Acoustics  

NASA Astrophysics Data System (ADS)

Medical acoustics can be subdivided into diagnostics and therapy. Diagnostics are further separated into auditory and ultrasonic methods, and both employ low amplitudes. Therapy (excluding medical advice) uses ultrasound for heating, cooking, permeablizing, activating and fracturing tissues and structures within the body, usually at much higher amplitudes than in diagnostics. Because ultrasound is a wave, linear wave physics are generally applicable, but recently nonlinear effects have become more important, even in low-intensity diagnostic applications.

Beach, Kirk; Dunmire, Barbrina

287

High-Dose Hypofractionated Proton Beam Radiation Therapy Is Safe and Effective for Central and Peripheral Early-Stage Non-Small Cell Lung Cancer: Results of a 12-Year Experience at Loma Linda University Medical Center  

SciTech Connect

Purpose: We update our previous reports on the use of hypofractionated proton beam radiation therapy for early-stage lung cancer patients. Methods and Materials: Eligible subjects had biopsy-proven non-small cell carcinoma of the lung and were medically inoperable or refused surgery. Clinical workup required staging of T1 or T2, N0, M0. Subjects received hypofractionated proton beam therapy to the primary tumor only. The dose delivered was sequentially escalated from 51 to 60 Gy, then to 70 Gy in 10 fractions over 2 weeks. Endpoints included toxicity, pulmonary function, overall survival (OS), disease-specific survival (DSS), and local control (LC). Results: One hundred eleven subjects were analyzed for treatment outcomes. The patient population had the following average characteristics; age 73.2 years, tumor size 3.6 cm, and 1.33 L forced expiratory volume in 1 second. The entire group showed improved OS with increasing dose level (51, 60, and 70 Gy) with a 4-year OS of 18%, 32%, and 51%, respectively (P=.006). Peripheral T1 tumors exhibited LC of 96%, DSS of 88%, and OS of 60% at 4 years. Patients with T2 tumors showed a trend toward improved LC and survival with the 70-Gy dose level. On multivariate analysis, larger tumor size was strongly associated with increased local recurrence and decreased survival. Central versus peripheral location did not correlate with any outcome measures. Clinical radiation pneumonitis was not found to be a significant complication, and no patient required steroid therapy after treatment for radiation pneumonitis. Pulmonary function was well maintained 1 year after treatment. Conclusions: High-dose hypofractionated proton therapy achieves excellent outcomes for lung carcinomas that are peripherally or centrally located. The 70-Gy regimen has been adopted as standard therapy for T1 tumors at our institution. Larger T2 tumors show a trend toward improved outcomes with higher doses, suggesting that better results could be seen with intensified treatment.

Bush, David A., E-mail: dbush@llu.edu [Department of Radiation Oncology, Loma Linda University Medical Center, Loma Linda, California (United States); Cheek, Gregory [Department of Pulmonary Medicine, Loma Linda University Medical Center, Loma Linda, California (United States); Zaheer, Salman; Wallen, Jason [Department of Thoracic Surgery, Loma Linda University Medical Center, Loma Linda, California (United States); Mirshahidi, Hamid [Department of Medical Oncology, Loma Linda University Medical Center, Loma Linda, California (United States); Katerelos, Ari; Grove, Roger; Slater, Jerry D. [Department of Radiation Oncology, Loma Linda University Medical Center, Loma Linda, California (United States)

2013-08-01

288

Women and small cell lung cancer: social characteristics, medical history, management and survival: a retrospective study of all the male and female cases diagnosed in Bas-Rhin (Eastern France) between 1981 and 1994.  

PubMed

The literature make it clear that lung cancer in women differs from that in men in several specific aspects. We conducted a retrospective study of the 967 consecutive recorded patients (696 men and 91 women after exclusions) diagnosed with small cell lung cancers (SCLC) between 1981 and 1994 in the Bas-Rhin population-based cancer registry to determine if such particularities could be observed in SCLC. Data included demographic and social characteristics, medical and smoking history, management (diagnosis and treatment), hospitalisation and survival. The end point for survival was 31 December 1998. Women were more frequently single, divorced, or widowed (P=0.007) and lived more often in urban areas (places with more than 10,000 inhabitants) (P=0.017). They differed significantly from men in their tobacco exposure (P=0.0001) and non-smoking rates (P=0.0003) but not in clinical presentation, except for more frequently elevated LDH levels (P=0.02). Bone marrow biopsies were more often performed in men (P=0.004), but management was otherwise comparable. The mean number of hospitalisations (for any reason) was comparable in both sexes but women tended to remain hospitalised longer (P=0.057). Overall survival did not differ, but women older than 70 years died sooner than their male counterparts (P=0.026). Our study confirms that some of gender differences reported in the lung cancer literature exist in SCLC. Sex-related differences in LDH levels have not previously been reported, to our knowledge. North American and European data concerning survival among women and men are discordant. Whether these gender differences are related to a real difference between the sexes or simply to differential exposure to carcinogens remains to be determined. PMID:14568681

Mennecier, Bertrand; Lebitasy, Marie-Paule; Moreau, Lionel; Hedelin, Guy; Purohit, Ashok; Galichet, Cedric; Quoix, Elisabeth

2003-11-01

289

Long-term results of high-dose conformal radiotherapy for patients with medically inoperable T1-3N0 non-small-cell lung cancer: Is low incidence of regional failure due to incidental nodal irradiation?  

SciTech Connect

Purpose: To report the results of high-dose conformal irradiation and examine incidental nodal irradiation and nodal failure in patients with inoperable early-stage non-small-cell lung cancer (NSCLC). Methods and Materials: This analysis included patients with inoperable CT-staged T1-3N0M0 NSCLC treated on our prospective dose-escalation trial. Patients were treated with radiation alone (total dose, 63-102.9 Gy in 2.1-Gy daily fractions) with a three-dimensional conformal technique without intentional nodal irradiation. Bilateral highest mediastinal and upper/lower paratracheal, prevascular and retrotracheal, sub- and para-aortic, subcarinal, paraesophageal, and ipsilateral hilar regions were delineated individually. Nodal failure and doses of incidental irradiation were studied. Results: The potential median follow-up was 104 months. For patients who completed protocol treatment, median survival was 31 months. The actuarial overall survival rate was 86%, 61%, 43%, and 21% and the cause-specific survival rate was 89%, 70%, 53%, and 35% at 1, 2, 3, and 5 years, respectively. Weight loss (p = 0.008) and radiation dose in Gy (p = 0.013) were significantly associated with overall survival. In only 22% and 13% of patients examined did ipsilateral hilar and paratracheal (and subaortic for left-sided tumor) nodal regions receive a dose of {>=}40 Gy, respectively. Less than 10% of all other nodal regions received a dose of {>=}40 Gy. No patients failed initially at nodal sites. Conclusions: Radiation dose is positively associated with overall survival in patients with medically inoperable T1-3N0 NSCLC, though long-term results remain poor. The nodal failure rate is low and does not seem to be due to high-dose incidental irradiation.

Chen Ming [Department of Radiation Oncology, University of Michigan Health System, Ann Arbor, MI (United States); Hayman, James A. [Department of Radiation Oncology, University of Michigan Health System, Ann Arbor, MI (United States); Haken, Randall K. ten [Department of Radiation Oncology, University of Michigan Health System, Ann Arbor, MI (United States); Tatro, Daniel [Department of Radiation Oncology, University of Michigan Health System, Ann Arbor, MI (United States); Fernando, Shaneli [Department of Radiation Oncology, Veterans Administration Medical Center, Ann Arbor, MI (United States); Kong, F.-M. [Department of Radiation Oncology, University of Michigan Health System, Ann Arbor, MI (United States) and Department of Radiation Oncology, Veterans Administration Medical Center, Ann Arbor, MI (United States)]. E-mail: fengkong@med.umich.edu

2006-01-01

290

Electromagnetic ion cyclotron resonance heating in the VASIMR  

NASA Astrophysics Data System (ADS)

Plasma physics has found an increasing range of practical industrial applications, including the development of electric spacecraft propulsion systems. One of these systems, the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) engine, both applies several important physical processes occurring in the magnetosphere. These processes include the mechanisms involved in the ion acceleration and heating that occur in the Birkeland currents of an auroral arc system. Auroral current region processes that are simulated in VASIMR include lower hybrid heating, parallel electric field acceleration and ion cyclotron acceleration. This paper will focus on using a physics demonstration model VASIMR to study ion cyclotron resonance heating (ICRH). The major purpose is to provide a VASIMR status report to the COSPAR community. The VASIMR uses a helicon antenna with up to 20 kW of power to generate plasma. This plasma is energized by an RF booster stage that uses left hand polarized slow mode waves launched from the high field side of the ion cyclotron resonance. The present setup for the booster uses 2 4 MHz waves with up to 20 kW of power. This process is similar to the ion cyclotron heating in tokamaks, but in the VASIMR the ions only pass through the resonance region once. The rapid absorption of ion cyclotron waves has been predicted in recent theoretical studies. These theoretical predictions have been supported with several independent measurements in this paper. The ICRH produced a substantial increase in ion velocity. Pitch angle distribution studies show that this increase takes place in the resonance region where the ion cyclotron frequency is equal to the frequency on the injected RF waves. Downstream of the resonance region the perpendicular velocity boost should be converted to axial flow velocity through the conservation of the first adiabatic invariant as the magnetic field decreases in the exhaust region of the VASIMR. In deuterium plasma, 80% efficient absorption of 20 kW of ICRH input power has been achieved. No evidence for power limiting instabilities in the exhaust beam has been observed.

Bering, E. A.; Chang-Díaz, F. R.; Squire, J. P.; Brukardt, M.; Glover, T. W.; Bengtson, R. D.; Jacobson, V. T.; McCaskill, G. E.; Cassady, L.

2008-07-01

291

Trends of Medication Errors in Hospitalized Children  

Microsoft Academic Search

Medication errors are a major cause of morbidity and mortality among hospitalized children. Due to the small volumes of stock solution involved, even a large error may look as an unsuspiciously small dose. Strategies were implemented to reduce medication errors in a large tertiary pediatric hospital in Toronto. Starting in 1993, several initiatives were taken, including a newhospital computer system

Gideon Koren

2002-01-01

292

Medical Transcriptionists: Making Medical Histories.  

ERIC Educational Resources Information Center

Medical transcriptionists are experts in the language of medicine. Describes what they do and what their working conditions, earnings, employment prospects, and training requirements are. Includes sources of additional information. (Author)

Shniper, Lynn

2001-01-01

293

Sawtooth control in ITER using ion cyclotron resonance heating  

NASA Astrophysics Data System (ADS)

Numerical modelling of the effects of ion cyclotron resonance heating (ICRH) on the stability of the internal kink mode suggests that ICRH should be considered as an essential sawtooth control tool in ITER. Sawtooth control using ICRH is achieved by directly affecting the energy of the internal kink mode rather than through modification of the magnetic shear by driving localized currents. Consequently, ICRH can be seen as complementary to the planned electron cyclotron current drive actuator, and indeed will improve the efficacy of current drive schemes. Simulations of the ICRH distribution using independent RF codes give confidence in numerical predictions that the stabilizing influence of the fusion-born alphas can be negated by appropriately tailored minority 3He ICRH heating in ITER. Finally, the effectiveness of all sawtooth actuators is shown to increase as the q = 1 surface moves towards the manetic axis, whilst the passive stabilization arising from the alpha and NBI particles decreases.

Chapman, I. T.; Graves, J. P.; Johnson, T.; Asunta, O.; Bonoli, P.; Choi, M.; Jaeger, E. F.; Jucker, M.; Sauter, O.

2011-12-01

294

PHYSICS OF ELCTRON CYCLOTRON CURRENT DRIVE ON DIII-D  

SciTech Connect

OAK A271 PHYSICS OF ELCTRON CYCLOTRON CURRENT DRIVE ON DIII-D. Recent experiments on the DIII-D tokamak have focused on determining the effect of trapped particles on the electron cyclotron current drive (ECCD) efficiency. The measured ECCD efficiency increases as the deposition location is moved towards the inboard midplane or towards smaller minor radius for both co and counter injection. The measured ECCD efficiency also increases with increasing electron density and/or temperature. The experimental ECCD is compared to both the linear theory (Toray-GA) as well as a quasilinear Fokker-Planck model (CQL3D). The experimental ECCD is found to be in better agreement with the more complete Fokker-Planck calculation, especially for cases of high rf power density and/or loop voltage. The narrow width of the measured ECCD profile is consistent with only low levels of radial transport for the current carrying electrons.

PETTY,CC; PRATER,R; LUCE,TC; ELLIS,RA; HARVEY,RW; KINSEY,JE; LAO,LL; LOHR,J; MAKOWSKI,MA

2002-09-01

295

Proton-cyclotron and firehose instabilities in inhomogeneous plasmas  

NASA Astrophysics Data System (ADS)

By combining the kinetic-fluid model for macroscopic quantities and quasilinear kinetic theory for microscopic plasma instabilities, the present paper investigates quasi-stationary spatial distribution and characteristics of the electromagnetic proton-cyclotron and parallel firehose instabilities in inhomogeneous plasma, as well as their influence on macroscopic variables. The present paper considers diverging magnetic field along a flux tube, as well as the associated density model, with various source region boundary conditions, in order to investigate the spatial locations at which the excitation, saturation, and damping of the proton-cyclotron and firehose instabilities occur in a medium with field-aligned inhomogeneity. Potential application may be on the solar wind model in which the temperature anisotropy threshold rigorously follows as a result of quasilinear relaxation process.

Yoon, Peter H.; Seough, Jungjoon

2014-09-01

296

Ion Behavior in an Electrically Compensated Ion Cyclotron Resonance Trap  

PubMed Central

We recently described a new electrically compensated trap in FT ion cyclotron resonance mass spectrometry and developed a means of tuning traps of this general design. Here, we describe a continuation of that research by comparing the ion transient lifetimes and the resulting mass resolving powers and signal-to-noise (S/N) ratios that are achievable in the compensated vs. uncompensated modes of this trap. Transient lifetimes are ten times longer under the same conditions of pressure, providing improved mass resolving power and S/N ratios. The mass resolving power as a function of m/z is linear (log-log plot) and nearly equal to the theoretical maximum. Importantly, the ion cyclotron frequency as a function of ion number decreases linearly in accord with theory, unlike its behavior in the uncompensated mode. This linearity should lead to better control in mass calibration and increased mass accuracy than achievable in the uncompensated mode. PMID:21499521

Brustkern, Adam M.; Rempel, Don L.; Gross, Michael L.

2010-01-01

297

Phase-Resolved Cyclotron Spectroscopy of MQ Draconis  

NASA Astrophysics Data System (ADS)

We model phase-resolved spectra of the polar MQ Dra with both a constant-lambda prescription as well as with a structured shock code built by \\cite{Fischer2001}. In each case, the observed spectra are well fit with a shock of B ? 59 MG and kTmax ? 1.5 keV. However, the orbital morphology of the cyclotron spectra cannot be explained with a simple geometry (constant inclination, i, and magnetic co-latitude, ?), as the implied cyclotron maximum of such models occur at apparent photometric minimum. We explain this anomaly as an effect of foreshortening of the accretion region. However, the foreshortening curves can only work for geometries in which the local field line angle (``b'') to the emission region is continuously variable throughout the orbit.

Campbell, R. K.; Harrison, T. E.

2009-08-01

298

On the cyclotron line in Cep X-4  

E-print Network

Accreting X-ray pulsars provide us with laboratories for the study of extreme gravitational and magnetic fields, hence accurate descriptions of their observational properties contribute to our understanding of this group of objects. We aim to detect a cyclotron resonance scattering feature in the Be/X-ray binary Cep X-4 and to investigate pulse profile and spectral changes through the outburst. Spectral fitting and timing analysis are employed to probe the properties of Cep X-4 during an outburst in 2002 June. A previously announced cyclotron feature at 30.7 keV is confirmed, while the source shows spectral behaviour and luminosity related changes similar to those observed in previous outbursts. The long-term X-ray lightcurve shows a periodicity at 20.85 d, which could be attributed to the orbit in this Be system.

V. A. McBride; J. Wilms; I. Kreykenbohm; M. J. Coe; R. E. Rothschild; P. Kretschmar; K. Pottschmidt; J. Fisher; T. Hamson

2007-05-21

299

Radiation protection aspects of the operation in a cyclotron facility  

NASA Astrophysics Data System (ADS)

The activated accelerator cyclotron components and the radioisotope production may impact on the personnel radiation exposure of the workers during the routine maintenance and emergency repair procedures and any modification of the equipment. Since the adherence of the principle of ALARA (as low as reasonable achievable) constitutes a major objective of the cyclotron management, it has become imperative to investigate the radiation levels at the workplace and the probable health effects to the worker caused by radiation exposure. The data analysis in this study was based on the individual monitoring records during the period from 2007 to 2011. Monitoring of the workplace was also performed using gamma and neutron detectors to determine the dose rate in various predetermined spots. The results of occupational radiation exposures were analysed and compared with the values established in national standards and international recommendations. Important guidelines have been developed to reduce the individual dose.

Silva, P. P. N.; Carneiro, J. C. G. G.

2014-02-01

300

Fourier transform ion cyclotron resonance mass resolution and dynamic range limits calculated by computer modeling of ion cloud motion.  

PubMed

Particle-in-Cell (PIC) ion trajectory calculations provide the most realistic simulation of Fourier transform ion cyclotron resonance (FT-ICR) experiments by efficient and accurate calculation of the forces acting on each ion in an ensemble (cloud), including Coulomb interactions (space charge), the electric field of the ICR trap electrodes, image charges on the trap electrodes, the magnetic field, and collisions with neutral gas molecules. It has been shown recently that ion cloud collective behavior is required to generate an FT-ICR signal and that two main phenomena influence mass resolution and dynamic range. The first is formation of an ellipsoidal ion cloud (termed "condensation") at a critical ion number (density), which facilitates signal generation in an FT-ICR cell of arbitrary geometry because the condensed cloud behaves as a quasi-ion. The second phenomenon is peak coalescence. Ion resonances that are closely spaced in m/z coalesce into one resonance if the ion number (density) exceeds a threshold that depends on magnetic field strength, ion cyclotron radius, ion masses and mass difference, and ion initial spatial distribution. These two phenomena decrease dynamic range by rapid cloud dephasing at small ion density and by cloud coalescence at high ion density. Here, we use PIC simulations to quantitate the dependence of coalescence on each critical parameter. Transitions between independent and coalesced motion were observed in a series of the experiments that systematically varied ion number, magnetic field strength, ion radius, ion m/z, ion m/z difference, and ion initial spatial distribution (the present simulations begin from elliptically-shaped ion clouds with constant ion density distribution). Our simulations show that mass resolution is constant at a given magnetic field strength with increasing ion number until a critical value (N) is reached. N dependence on magnetic field strength, cyclotron radius, ion mass, and difference between ion masses was determined for two ion ensembles of different m/z, equal abundance, and equal cyclotron radius. We find that N and dynamic range depend quadratically on magnetic field strength in the range 1-21 Tesla. Dependences on cyclotron radius and ?m/z are linear. N depends on m/z as (m/z)(-2). Empirical expressions for mass resolution as a function of each of the experimental parameters are presented. Here, we provide the first exposition of the origin and extent of trade-off between FT-ICR MS dynamic range and mass resolution (defined not as line width, but as the separation between the most closely resolved masses). PMID:22033889

Vladimirov, Gleb; Hendrickson, Christopher L; Blakney, Greg T; Marshall, Alan G; Heeren, Ron M A; Nikolaev, Eugene N

2012-02-01

301

Multimegawatt DAE$\\delta$ALUS Cyclotrons for Neutrino Physics  

E-print Network

DAE$\\delta$ALUS (Decay-At-rest Experiment for $\\delta_{CP}$ studies At the Laboratory for Underground Science) provides a new approach to the search for CP violation in the neutrino sector. High-power continuous-wave proton cyclotrons efficiently provide the necessary proton beams with an energy of up to 800 MeV to create neutrinos from pion and muon decay-at-rest. The experiment searches for $\\bar{\

Abs, M; Alonso, J R; Barletta, W A; Barlow, R; Calabretta, L; Calanna, A; Campo, D; Celona, L; Conrad, J M; Gammino, S; Kleeven, W; Koeth, T; Maggiore, M; Okuno, H; Piazza, L A C; Seidel, M; Shaevitz, M H; Stingelin, L; Yang, J J; Yeck, J

2012-01-01

302

Neutron Field Characterization in the Vicinity of a PET Cyclotron  

Microsoft Academic Search

Neutron energy spectra and angular distributions were measured inside the vault room of a positron emission tomography (PET) cyclotron. The undesirable neutron fields produced during the interaction of 17.2-MeV protons and 8.2-MeV deuterons with the Faraday cup, and 8.2-MeV deuterons on nitrogen-14 were measured at three different locations inside the vault room: in front of the target position, at the

Hector Rene Vega-Carrillo

1995-01-01

303

Vanishing of Cyclotron Resonance in Correlated 2D Electron Systems  

Microsoft Academic Search

Experimental measurements of photoresistivity under terahertz (THz) radiation in low magnetic fields at conditions of cyclotron resonance (CR) in two-dimensional electron system (2DES) of GaAs\\/AlGaAs nanostructures are presented and discussed. We report the experimental discovery of CR-vanishing effect (CRV) in GaAs\\/AlGaAs heterostructures with high mobility as a well-defined gap on CR-line that is independent on incident THz power. Our analysis

Andre Chebotarev; Galina Chebotareva

2009-01-01

304

Electron cyclotron heating correlation with tokamak toroidal plasma rotation  

Microsoft Academic Search

Toroidal rotation of the central plasma core has been observed prior to and during electron cyclotron heating (ECH) in the Doublet III tokamak (in Plasma Physics and Controlled Nuclear Fusion Research 1984, Proceedings of the Tenth International Conference, London (IAEA, Vienna, 1985), Vol. 1, p. 131). Measurements were made using a curved-crystal Bragg x-ray spectrometer with spectral resolution of lambda\\/..delta..lambda

A. J. Lieber; R. T. Snider; Ping Lee; S. S. Wojtowicz

1988-01-01

305

Electron cyclotron heating correlation with tokamak toroidal plasma rotation  

Microsoft Academic Search

Toroidal rotation of the central plasma core has been observed prior to and during electron cyclotron heating (ECH) in the Doublet III tokamak [in PlasmaPhysicsandControlledNuclearFusionResearch 1984, Proceedings of the Tenth International Conference, London (IAEA, Vienna, 1985), Vol. 1, p. 131]. Measurements were made using a curved-crystal Bragg x-ray spectrometer with spectral resolution of ?\\/?? of greater than 19 000 and

A. J. Lieber; R. T. Snider; Ping Lee; S. S. Wojtowicz

1988-01-01

306

Electron Cyclotron Resonance heating system on Tokamak Aditya  

Microsoft Academic Search

An Electron Cyclotron Resonance Frequency (ECRF) system has been installed and commissioned for operation on tokamak Aditya. The system would serve dual purpose of electron heating during a normal discharge and initial breakdown to help increase the operational window. The 200 KW gyrotron, VGA-8000A19, operating at a frequency of 28+\\/-0.1 GHz is first commissioned into a dummy load for pulsed

K. Sathyanarayana; B. K. Shukla; D. Bora; S. Rajashree; K. Bhattacharya; Barnali Pal; Sanjay Kulkarni; Sampa Gangopadhyay; Y. S. S. Srinivas; P. L. Khilar; Mahesh Kushwah; R. G. Trivedi; D. Rathi; B. R. Kadia; Ashish Patel; Chetan Virani; Harshida Patel; H. M. Jadav; K. G. Parmar; P. Shah; A. R. Makwana; Sunil Dani; P. Kirit; M. Harsha

2001-01-01

307

Radiochemical studies at the cyclotron laboratory, Tohoku university  

NASA Astrophysics Data System (ADS)

In order to achieve a progressive experimental program, a new system for radioisotope production has been developed at one of the beam-courses of a multipurpose Cyclotron of K=110 MeV. The upgraded beam-course is useful for the study of the nuclear physics and chemistry of heavy elements, radiopharmaceutical studies, the production of radioactive tracers, activation analysis using charged particles, etc. Several topics are demonstrated in the field of radioanalytical and nuclear studies.

Ohtsuki, T.; Shikano, K.; Yuki, H.; Hirose, K.; Takamiya, K.

2006-01-01

308

Converting an AEG Cyclotron to H? Acceleration and Extraction  

NASA Astrophysics Data System (ADS)

Clinical Trials are under way to evaluate agents labeled with the nuclide 225Ac and its decay product 213Bi, in targeted alpha-immuno-therapy [1]. 225Ac can be produced on a medium-energy cyclotron via the nuclear reaction 226Ra(p,n)225Ac. To demonstrate proof-of-principle, a vintage AEG cyclotron, Model E33 [2], with an internal target, had been employed in a pilot production program at the Technical University of Munich (TUM). To enhance production capability and further support the clinical studies, the TUM facility has recently been refurbished and upgraded, adding a new external beam-line, automated target irradiation and transport systems, new laboratories, hot cells, etc. [3]. An improved high-power rotating target has been built and installed [4]. The AEG cyclotron itself has also been modified and upgraded to accelerate and extract H? ions. We have designed, built, and tested a new axial Penning-type ion source which is optimized for the production of H? ions. The ion source has continued to evolve through experiment and experience. Steady improvements in materials and mechanics have led to enhanced source stability, life-time, and H? production. We have also designed and built a precision H? charge-exchange beam-extraction system which is equipped with a vacuum lock. To fit within the tight mechanical constraint imposed by the narrow magnet gap, the system incorporates a novel chain-drive foil holder and foil-changer mechanism. The reconfigured cyclotron system has now been in operation for more than 1 year. Three long-duration target irradiations have been conducted. The most recent bombardment ran 160 continuous hours at a beam on target of ˜80 microamperes for a total yield of ˜70 milli-curies of 225Ac.

Ramsey, Fred; Carroll, Lewis; Rathmann, Tom; Huenges, Ernst; Bechtold, Matthias Mentler Volker

2009-03-01

309

Electron cyclotron current drive in DIII-D  

SciTech Connect

Clear measurements of the localized current density driven by electron cyclotron waves have been made on the DIII-D tokamak. Direct evidence of the current drive is seen on the internal magnetic field measurements by motional Stark effect spectroscopy. Comparison with theoretical calculations in the collisionless limit shows the experimental current drive exceeds the predictions by a substantial amount for currents driven near the half radius. In all cases the experimental current density profile is broader than the predicted one.

Luce, T.C.; Lin-Liu, Y.R.; Lohr, J.M.; Petty, C.C.; Politzer, P.A.; Prater, R. [General Atomics, San Diego, CA (United States); Harvey, R.W. [CompX, Del Mar, CA (United States); Giruzzi, G. [CEA, Saint Paul les Durance (France). Centre d`Etudes de Cadarache; Rice, B.W. [Lawrence Livermore National Lab., CA (United States)

1999-05-01

310

Electron cyclotron heating on the ISX-B tokamak  

SciTech Connect

One experiment on electron cyclotron heating on the Impurity Study Experiment (ISX-b) tokamak has been completed and a second experiment is in progress. In the first experiment, with a gyrotron producing 100 kW at 35 GHz, a heating efficiency greater than 60% was achieved. Unpolarized radiation was launched from the high field side of the tokamak, heating electrons at cyclotron resonance in the center of the plasma. From laser scattering and thermal emission at the second gyroharmonic, the electron temperature, initially 850 eV, increased to 1250 eV at the end of a 15-ms pulse. The second experiment is now in progress, with 180 kW at 28 GHz and a capability of 100-ms pulses. A comparison between polarized and unpolarized radiation, modification of the plasma current profile, and a critical comparison with theory are planned. In this paper, experiments on preionization at the upper hybrid resonance are reported. A plasma with an electron temperature of 10 eV was produced, which is not high enough to reduce impurity radiation. The resistive part of the loop voltage was reduced by preionization. Plans for an experiment to measure electric current induced by electron cyclotron heating are presented, along with a review of the theoretical basis of the current drive.

Eldridge, O.C.; England, A.C.; Gilgenbach, R.M.; Hackett, K.F.; Kulchar, A.G.; Loring, C.M.; Wilgen, J.B.

1980-01-01

311

Apparent electrostatic ion cyclotron waves in the diffuse aurora  

NASA Technical Reports Server (NTRS)

Emissions that have properties consistent with electrostatic ion cyclotron (EIC) waves have been observed at low altitude in the diffuse aurora by a sounding rocket payload. Peaks were observed in the power spectrum of the electric field near the hydrogen and oxygen ion cyclotron frequencies. Doppler shift and polarization analyses have been performed using EIC wave parameters derived from linear theory. Both analyses indicated that these emissions had properties consistent with those expected for H(+) and O(+) EIC waves. The two analyses indicated that both emission bands were due to waves propagating eastward parallel to the poleward boundary of the diffuse aurora. The large local cold plasma density and resulting Landau damping require that the source be local. Magnetometer data indicated the presence of a downward parallel current density of 5 microamps/sq m. Sufficient free energy for the waves was available from this current, although the waves were observed frequently at altitudes where the ion-neutral collision frequency exceeded the oxygen cyclotron frequency.

Bering, E. A.

1983-01-01

312

High Power Ion Cyclotron Heating in the VASIMR  

NASA Astrophysics Data System (ADS)

The Variable Specific Impulse Magnetoplasma Rocket (VASIMR®) is an electric propulsion system under development at Ad Astra Rocket Company that utilizes several processes of ion acceleration and heating that occur in the Birkeland currents of an auroral arc system. Among these processes are parallel electric field acceleration, lower hybrid resonance heating, and ion cyclotron resonance heating. The VASIMR® is capable of laboratory simulation of electromagnetic ion cyclotron wave heating during a single pass of ions through the resonance region. The plasma is generated by a helicon discharge of 35 kW then passes through a 176 kW RF booster stage that couples left hand polarized slow mode waves from the high field side of the resonance. VX-200 auroral simulation results from the past year are discussed. Ambipolar acceleration has been shown to produce 35eV argon ions in the helicon exhaust. The effects on the ion exhaust with an addition of 150-200 kW of ion cyclotron heating are presented. The changes to the VASIMR® experiment at Ad Astra Rocket Company's new facility in Webster, Texas will also be discussed, including the possibility of collaborative experiments.

Longmier, B. W.; Brukardt, M. S.; Bering, E. A.; Chang Diaz, F.; Squire, J.

2009-12-01

313

Electromagnetic ion beam instabilities - Growth at cyclotron harmonic wave numbers  

NASA Technical Reports Server (NTRS)

The linear theory of electromagnetic ion beam instabilities for arbitrary angles of propagation is studied, with an emphasis on the conditions necessary to generate unstable modes at low harmonics of the ion cyclotron resonance condition. The present results extend the analysis of Smith et al. (1985). That paper considered only the plasma parameters at a time during which harmonic wave modes were observed in the earth's foreshock. The parameters of that paper are used as the basis of parametric variations here to establish the range of beam properties which may give rise to observable harmonic spectra. It is shown that the growth rates of both left-hand and right-hand cyclotron harmonic instabilities are enhanced by an increase in the beam temperature anisotropy and/or the beam speed. Decreases in the beam density and/or the core-ion beta reduce the overall growth of the cyclotron harmonic instabilities but favor the growth of these modes over the growth of the nonresonant instability and thereby enhance the observability of the harmonics.

Smith, Charles W.; Gary, S. Peter

1987-01-01

314

Improving cancer treatment with cyclotron produced radionuclides. Progress report  

SciTech Connect

Our goal is to improve the scientific basis for tumor diagnosis, treatment and treatment follow-up based on the use of cyclotron produced radiotracers in oncology. The grant includes 3 interactive components: Radiochemistry/Cyclotron; Pharmacology; and Immunology. The radiochemistry group seeks to develop innovative cyclotron targetry, radiopharmaceuticals, and radiolabeled antibodies, which are then used to assess important unanswered questions in tumor pharmacology and immunology. Examples include selected positron emitting radionuclides, such as Iodine-124, and Ga-66; I-124, I-123, I-131 labeled iododeoxyuridine, C-11 colchicine, and antimetabolites, like C-11 methotrexate; and radiolabeled antibodies, 3F8, M195, A33, and MRK16 for application in the pharmacology and immunology projects. The pharmacology program studies tumor resistance to chemotherapy, particularly the phenomenon of multidrug resistance and the relationship between tumor uptake and retention and the tumor response for anti-metabolite drugs. The immunology program studies the physiology of antibody localization at the tissue level as the basis for novel approaches to improving tumor localization such as through the use of an artificial lymphatic system which mechanically reduces intratumoral pressures in tumors in vivo. Quantitative imaging approaches based on PET and SPECT in radioimmunotherapy are studied to give greater insight into the physiology of tumor localization and dosimetry.

Larson, S.M.; Finn, R.D.

1992-08-04

315

Production of carbon stripper foils for high-power cyclotrons  

NASA Astrophysics Data System (ADS)

TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics operates three industrial negative ion cyclotrons for commercial radioisotope production. Two of these cyclotrons (TR30 and TR30-2) can deliver 30 MeV protons at beam currents in excess of 1000 ?A and are designed for optional dual beam extraction and continuous operation. High-power negative ion accelerators use stripper foils as thick as 500 ?g/cm 2. It has been found that very smooth films with nanocrystalline microstructure perform the best in high-current applications. However, high-quality thick foils with good uniformity are difficult to manufacture. To meet our specific requirements, we have developed a carbon arc deposition system capable of producing durable, homogeneous carbon stripper foils. In this paper, we report on the fabrication of carbon foils with a thickness of 100-200 ?g/cm 2. The manufacturing equipment capable of producing ˜600 cm 2 of foil in a single run and the process details are described. Properties of these foils and their performance in the cyclotron are discussed.

Jaggi, V.; Pavan, R. A.; Zeisler, S. K.

2006-05-01

316

Cryogenic system upgrade for the National Superconducting Cyclotron Laboratory  

SciTech Connect

The National Superconducting Cyclotron Laboratory (NSCL) is a National Science Foundation supported facility, with additional support from Michigan State University (MSU). The facility consists of two superconducting cyclotrons and over fifty individual cryostats, each containing several superconducting magnets that are used in the beam transport system. The facility also has a superconducting ion source and a large superconducting spectrograph. To support this facility we operated two helium refrigerators producing approximate 900W at 4.5K. In July of 1999, construction of a new beam analysis system, the A1900, was started. The laboratory was reconfigured to couple the two cyclotrons in series to enable the facility to produce higher intensity radioactive beams than previously possible in the stand-alone mode. In addition, the helium distribution system was upgraded with new transfer lines and a new distribution box. The new requirements increased the refrigeration load to more than 1 KW at 4.5K. To support this increased cryogenic load, the existing two helium cryogenic plants, were at best, marginal in capacity. This would have required both plants to run at full capacity, maximum efficiency and availability. To achieve higher reliability, availability, and process transient capacity for magnet cool down and filling, a decision was made to obtain a larger cryogenic plant to support the new system. The following paper describes the important aspects and capabilities of the new cryogenic system to accomplish this goal.

A. McCartney; V. Ganni; H. Laumer; D. Arenius; J. Creel; W. Chronis; K. Davidson

2002-05-10

317

Considerations, measurements and logistics associated with low-energy cyclotron decommissioning  

NASA Astrophysics Data System (ADS)

The University of Iowa's 20-year-old 17 MeV Scanditronix cyclotron underwent decommissioning in the summer of 2011. To satisfy local, state and federal regulations defining removal, transportation and long-term safe and environmentally secure disposal of the 22 ton activated cyclotron, a series of nuclear spectroscopic measurements were performed to characterize the nature and extent of proton and neutron activation of the 22-ton cyclotron, its associated targets, and the concrete wall that was demolished to remove the old cyclotron. Neutron activation of the concrete wall was minimal and below exempt concentrations resulting in standard landfill disposal. The cyclotron assessment revealed the expected array of short and medium-lived radionuclides. Subsequent calculations suggest that meaningful levels residual activity will have decayed virtually to background after 15 years, with the total residual activity of the entire cyclotron dropping below 37 MBq (1 mCi).

Sunderland, J. J.; Erdahl, C. E.; Bender, B. R.; Sensoy, L.; Watkins, G. L.

2012-12-01

318

Backward mode of the ion-cyclotron wave in a semi-bounded magnetized Lorentzian plasma  

SciTech Connect

The backward modes of the surface ion-cyclotron wave are investigated in a semi-bounded magnetized Lorentzian plasma. The dispersion relation of the backward mode of the surface ion-cyclotron wave is obtained using the specular reflection boundary condition with the plasma dielectric function. The result shows that the nonthermal effect suppresses the wave frequency as well as the group velocity of the surface ion-cyclotron wave. It is also found that the nonthermal effect on the surface ion-cyclotron wave increases with an increase of the wave number. In addition, it is found that the propagation domain of the surface ion-cyclotron wave increases with an increase of the ratio of the electron plasma frequency to the electron gyrofrequency. It is also found that the nonthermal effect increases the propagation domain of the surface ion-cyclotron wave in a semi-bounded magnetized Lorentzian plasma.

Ki, Dae-Han [Department of Applied Physics, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of); Jung, Young-Dae [Department of Applied Physics, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of); Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, New York 12180-3590 (United States)

2012-08-15

319

Beam current oscillations driven by cyclotron instabilities in a minimum-B electron cyclotron resonance ion source plasma  

NASA Astrophysics Data System (ADS)

Experimental observation of cyclotron instabilities in a minimum-B confined electron cyclotron resonance ion source plasma is reported. The instabilities are associated with strong microwave emission and a burst of energetic electrons escaping the plasma, and explain the periodic ms-scale oscillation of the extracted beam currents. Such non-linear effects are detrimental for the confinement of highly charged ions due to plasma perturbations at shorter periodic intervals in comparison with their production time. It is shown that the repetition rate of the periodic instabilities in oxygen plasmas increases with increasing magnetic field strength and microwave power and decreases with increasing neutral gas pressure, the magnetic field strength being the most critical parameter. The occurrence of plasma turbulence is demonstrated to restrict the parameter space available for the optimization of extracted currents of highly charged ions.

Tarvainen, O.; Izotov, I.; Mansfeld, D.; Skalyga, V.; Golubev, S.; Kalvas, T.; Koivisto, H.; Komppula, J.; Kronholm, R.; Laulainen, J.; Toivanen, V.

2014-04-01

320

Status of a compact electron cyclotron resonance ion source for National Institute of Radiological Sciences-930 cyclotron.  

PubMed

The Kei-source is a compact electron cyclotron resonance ion source using only permanent magnets and a frequency of 10 GHz. It was developed at the National Institute of Radiological Sciences (NIRS) for producing C(4+) ions oriented for high-energy carbon therapy. It has also been used as an ion source for the NIRS-930 cyclotron. Its microwave band region for the traveling-wave-tube amplifier and maximum output power are 8-10 GHz and 350 W, respectively. Since 2006, it has provided various ion beams such as proton, deuteron, carbon, oxygen, and neon with sufficient intensity (200 ?A for proton and deuteron, 50 ?A for C(4+), for example) and good stability for radioisotope production, tests of radiation damage, and basic research experiments. Its horizontal and vertical emittances were measured using a screen monitor and waist-scan. The present paper reports the current status of the Kei-source. PMID:24593538

Hojo, S; Katagiri, K; Nakao, M; Sugiura, A; Muramatsu, M; Noda, A; Okada, T; Takahashi, Y; Komiyama, A; Honma, T; Noda, K

2014-02-01

321

Medical Instrumentation  

NSDL National Science Digital Library

Students learn about the sorts of devices designed by biomedical engineers and the many other engineering specialties that are required in their design of medical diagnostics, therapeutic aids, surgical devices and procedures, and replacement parts. They discuss the special considerations that must be made when dealing with the human body, such as being minimally invasive, biocompatible, keeping sterile, lightweight, corrosion resistant, long lasting and electrically safe. They also explore how "form fits function." Students gain an appreciation for the amazing devices that improve our quality of life. This lesson serves as a starting point for students to begin to ponder how the medical devices in their everyday lives work.

Techtronics Program

322

Medical marijuana.  

PubMed

The Florida Supreme Court heard oral arguments in April regarding a glaucoma patient's request for a medical exception to the State prohibition on use of marijuana. [Name removed] was convicted on possession and cultivation charges, and a trial judge refused to allow a medical necessity defense. A State appeals court subsequently overturned [name removed]'s conviction. The case focuses on whether the legislature intended to prohibit such a defense when it declared in 1993 that the substance had no medicinal benefits. PMID:11366533

1999-04-30

323

A new design of truly selfshielding baby-cyclotrons for positron emitter production  

Microsoft Academic Search

The successful design of the Cyclone 30, a 30-MeV H- cyclotron, gave birth to an original design of truly selfshielding baby-cyclotrons dedicated to positron emitter production. This new negative ion cyclotron will deliver 10-MeV protons and 5-MeV deuterons. Up to eight targets are located inside the circular return yoke of the magnet, which serves as a primary neutron and gamma-ray

M. Abs; J. L. Bol; A. Chevalier; E. Conrad; Y. Jongen; M. Lacroix; G. Lannoye; T. Ledocte; A. Ninane; G. Rijckewaert; S. Zaremba

1989-01-01

324

Linear and nonlinear physics of the magnetoacoustic cyclotron instability of fusion-born ions in relation to ion cyclotron emission  

NASA Astrophysics Data System (ADS)

The magnetoacoustic cyclotron instability (MCI) probably underlies observations of ion cyclotron emission (ICE) from energetic ion populations in tokamak plasmas, including fusion-born alpha-particles in JET and TFTR [Dendy et al., Nucl. Fusion 35, 1733 (1995)]. ICE is a potential diagnostic for lost alpha-particles in ITER; furthermore, the MCI is representative of a class of collective instabilities, which may result in the partial channelling of the free energy of energetic ions into radiation, and away from collisional heating of the plasma. Deep understanding of the MCI is thus of substantial practical interest for fusion, and the hybrid approximation for the plasma, where ions are treated as particles and electrons as a neutralising massless fluid, offers an attractive way forward. The hybrid simulations presented here access MCI physics that arises on timescales longer than can be addressed by fully kinetic particle-in-cell simulations and by analytical linear theory, which the present simulations largely corroborate. Our results go further than previous studies by entering into the nonlinear stage of the MCI, which shows novel features. These include stronger drive at low cyclotron harmonics, the re-energisation of the alpha-particle population, self-modulation of the phase shift between the electrostatic and electromagnetic components, and coupling between low and high frequency modes of the excited electromagnetic field.

Carbajal, L.; Dendy, R. O.; Chapman, S. C.; Cook, J. W. S.

2014-01-01

325

Medical marijuana.  

PubMed

Although many clinical studies suggest the medical utility of marijuana for some conditions, the scientific evidence is weak. Many patients in California are self-medicating with marijuana, and physicians need data to assess the risks and benefits. The only reasonable solution to this problem is to encourage research on the medical effects of marijuana. The current regulatory system should be modified to remove barriers to clinical research with marijuana. The NIH panel has identified several conditions for which there may be therapeutic benefit from marijuana use and that merit further research. Marijuana should be held to the same evaluation standards of safety and efficacy as other drugs (a major flaw in Proposition 215) but should not have to be proved better than current medications for its use to be adopted. The therapeutic window for marijuana and THC between desired effect and unpleasant side effects is narrow and is a major reason for discontinuing use. Although the inhaled route of administration has the benefit of allowing patients to self-titrate the dose, the smoking of crude plant material is problematic. The NIH panel recommended that a high priority be given to the development of a controlled inhaled form of THC. The presence of a naturally occurring cannabinoid-receptor system in the brain suggests that research on selective analogues of THC may be useful to enhance its therapeutic effects and minimize adverse effects. PMID:9656007

Marmor, J B

1998-06-01

326

Microwave-Excited Microplasma Thrusters Using Surface Wave and Electron Cyclotron Resonance Discharges  

NASA Astrophysics Data System (ADS)

Downsizing spacecrafts has recently been focused on to decrease mission costs and to increase launch rates, and missions with small satellites would bring a great advantage of reducing their risks. Such a concept supports a new approach to developing precise, reliable, and low-cost micropropulsion systems. We have studied two types of microwave-excited microplasma thrusters, using surface wave-excited and electron cyclotron resonance-excited discharges. Microwaves of S-band (4 GHz) and X-band (11 GHz) were employed to excite the plasma in these experiments, with the feed or propellant gases of Ar and He. A microplasma thruster of electrothermal type consisted of a surface wave-excited microplasma source, and a converging-diverging micronozzle to obtain the thrust. For 11-GHz microwaves at a power of 6 W, a thrust of 1.1 mN and a specific impulse of 90 s were obtained at an Ar gas flow rate of 40 sccm, where the plasma electron density was 1.2x10^20 m-3, and the gas temperature was 1.5x10^3 K; under the same conditions for 4-GHz microwaves, the thrust, specific impulse, electron density, and gas temperature were 0.93 mN, 80 s, 7.0x10^19 m-3, and 8.0x10^2 K, respectively. A microplasma thruster of electromagnetic type had a microplasma source excited by electron cyclotron resonance with external magnetic fields, to obtain the thrust through accelerating ions by ambipolar electric fields. Optical emission spectrum was dominated by Ar^+ ion lines in the microplasma thruster of electromagnetic type, owing to higher electron temperatures at lower feed-gas pressures.

Mori, Daisuke; Kawanabe, Tetsuo; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

2012-10-01

327

Low energy cyclotron production of multivalent transition metals for PET imaging and therapy  

NASA Astrophysics Data System (ADS)

Recent advances in high-resolution tomographs for small animals require the production of nonconventional long-lived positron emitters to label novel radiopharmaceuticals for PET-based molecular imaging. Radioisotopes with an appropriate half life to match the kinetics of slow biological processes will allow to researchers to study the phamacokinetics of PET ligands over several hours, or even days, on the same animal, with the injection of a single dose. In addition, radionuclides with a suitable half life can potentially be distributed from a central production site making them available in PET facilities that lack an in-house cyclotron. In the last few years there has been a growing interest in the use of PET ligands labeled with radiometals, particularly isotopes of copper, yttrium and zirconium. Future clinical applications of these tracers will require them to be produced reliably and efficiently. This thesis work deals with implementing and optimizing the production of the multivalent transition metals 61,64Cu, 86Y and 89Zr for molecular PET imaging and therapy. Our findings in the production of these radionuclides at high specific activity on an 11 MeV proton-only cyclotron are presented. Local applications of these tracers, including Cu-ATSM for in vivo quantification of hypoxia, synthesis of targeted radiopharmaceuticals using activated esters of DOTA, and a novel development of positron emitting resin microspheres, are also be discussed. As a result of this thesis work, metallic radionuclides are now efficiently produced on a weekly basis in sufficient quality and quantity for collaborating scientists at UW-Madison and external users in other Universities across the country.

Avila-Rodriguez, Miguel Angel

328

Medication reconciliation in hemodialysis patients.  

PubMed

Medication reconciliation is an effective process to reduce adverse drug events (ADEs) and harm associated with the loss of medication information as patients transfer between health care settings. Patients with end stage renal disease (ESRD) are at a high risk of experiencing drug-related problems (DRPs) because they take many medications, have multiple comorbidities, and require frequent medication changes. We evaluated the potential impact of medication reconciliation and optimization in the ambulatory care setting at the time of patient transfer from an in-centre dialysis unit to a satellite dialysis unit. Overall, 15 patients (78.8%) had at least one unintended medication variance. The majority of unintended variances (56%) were caused by the physician/nurse practitioner (NP) omitting an order for medication that the patient was taking. In this small study, medication reconciliation was effective at identifying and rectifying medication errors and optimizing pharmacotherapy at the time of transfer from an in-centre hemodialysis to a satellite dialysis unit. PMID:19175192

Ledger, Séadna; Choma, Gail

2008-01-01

329

Compact injector with alternating phase focusing-interdigital H-mode linac and superconducting electron cyclotron resonance ion source for heavy ion cancer therapy  

NASA Astrophysics Data System (ADS)

We have researched a compact medical accelerator with low investment and running cost for the popularization of heavy ion cancer therapy. As the first step, the compact injector system has been investigated for a Heavy Ion Medical Accelerator in Chiba at National Institute of Radiological Sciences. The proposed new injector system consists of a 6 MeV/u interdigital H-mode (IH) linac of 3.1 m long and a 18 GHz superconducting electron cyclotron resonance (ECR) (SC-ECR) ion source. The IH linac with high power efficiency is appropriate to a medical and industrial injector system. Its beam trajectory was simulated and a prototype has been constructed. The SC-ECR ion source has been designed to realize lightweight and low power consumption and the mirror field distribution was estimated.

Hayashizaki, Noriyosu; Hattori, Toshiyuki; Matsui, Shinjiro; Tomizawa, Hiromitsu; Yoshida, Toru; Isokawa, Katsushi; Kitagawa, Atsushi; Muramatsu, Masayuki; Yamada, Satoru; Okamura, Masahiro

2000-02-01

330

Medical Efficacy and Medical Ethics  

Microsoft Academic Search

The pro-life movement has a problem, an undiagnosed illness, as it were, which may cause the movement to self-destruct. It is a problem commonly found among those ardently involved in saving the lives of the unborn, the crippled, the senile and others unable to fend for themselves. The problem is an overvaluation of medical care often taking the form of

Hilton P. Terrell

331

Medication errors.  

PubMed

Medication errors cause substantial harm to patients. We need good methods for counting errors, and we need to know how errors defined in different ways and ascertained by different methods are related to the harm that patients suffer. As errors arise within the complex and poorly designed systems of hospital and primary care, analysis of the factors that lead to error, for example by failure mode and effects analysis, may encourage better designs and reduce harms. There is almost no information on the best ways to train prescribers to be safe or to design effective computerized decision support to help them, although both are important in reducing medication errors and should be investigated. We also need to know how best to provide patients with the data they need to be part of initiatives for safer prescribing. PMID:22360355

Ferner, Robin E

2012-06-01

332

Medical Thoracoscopy  

Microsoft Academic Search

As opposed to ‘video-assisted thoracoscopic surgery’ which requires general anesthesia, double-lumen tracheal intubation and single lung ventilation, medical thoracoscopy (or ‘pleuroscopy’) is frequently performed in the respiratory endoscopy suite using local anesthesia. It can be done by well-trained physicians, either pulmonologists or thoracic surgeons, and its main indication is related to diagnosis and treatment of pleural effusions. Also, pneumothorax can

Francisco Rodríguez-Panadero

2008-01-01

333

Cyclotron resonance precipitation of energetic electrons from the inner magnetosphere  

SciTech Connect

Cyclotron resonance between trapped energetic electrons and VLF waves produces pitch angle scattering which leads to electron precipitation in the inner magnetosphere. Previous experiments have shown that in the drift loss cone at L values from 1.5 to 1.8 energy spectrum of the electrons above 50 keV is often dominated by a single narrow peak. The center energy of this peak varies with L in a manner characteristic of cyclotron resonance between the electrons and monochromatic VLF waves in the vicinity of the geomagnetic equator. The source of the waves is probably VLF communication or navigation transmitters. The authors report the results of a study of 680 occurrences of these peaks detected by the low altitude polar orbiting satellite S81-1. The present data, from altitudes between 170 and 270 km, show the resonance peaks only in two restricted longitude zones centered at 100E and 300E; this result contrasts with the previous measurements at higher altitudes, which detected peaks over a wide range of longitudes. The majority of nighttime events were near transmitter locations where the cyclotron resonance condition was met by electrons with pitch angles near the edge of the loss cone. Detailed study of the events occurring near 100E reveals a 27-day periodicity in the frequency of occurrence; peaks are most often observed during minima in solar/geomagnetic activity. The peaks observed at nighttime in both longitude zones have a possible seasonal variation, being most frequent when it is wintertime at the site of the VLF transmitters responsible for the precipitation.

Datlowe, D.W.; Imhof, W.L. (Lockheed Palo Alto Lab., CA (United States))

1990-05-01

334

Electromagnetic Waves near the Proton Cyclotron Frequency: STEREO Observations  

NASA Astrophysics Data System (ADS)

Transverse, near-circularly polarized, parallel-propagating electromagnetic waves around the proton cyclotron frequency were found sporadically in the solar wind throughout the inner heliosphere. They could play an important role in heating and accelerating the solar wind. These low-frequency waves (LFWs) are intermittent but often occur in prolonged bursts lasting over 10 minutes, named "LFW storms." Through a comprehensive survey of them from Solar Terrestrial Relations Observatory A using dynamic spectral wave analysis, we have identified 241 LFW storms in 2008, present 0.9% of the time. They are left-hand (LH) or right-hand (RH) polarized in the spacecraft frame with similar characteristics, probably due to Doppler shift of the same type of waves or waves of intrinsically different polarities. In rare cases, the opposite polarities are observed closely in time or even simultaneously. Having ruled out interplanetary coronal mass ejections, shocks, energetic particles, comets, planets, and interstellar ions as LFW sources, we discuss the remaining generation scenarios: LH ion cyclotron instability driven by greater perpendicular temperature than parallel temperature or by ring-beam distribution, and RH ion fire hose instability driven by inverse temperature anisotropy or by cool ion beams. The investigation of solar wind conditions is compromised by the bias of the one-dimensional Maxwellian fit used for plasma data calibration. However, the LFW storms are preferentially detected in rarefaction regions following fast winds and when the magnetic field is radial. This preference may be related to the ion cyclotron anisotropy instability in fast wind and the minimum in damping along the radial field.

Jian, L. K.; Wei, H. Y.; Russell, C. T.; Luhmann, J. G.; Klecker, B.; Omidi, N.; Isenberg, P. A.; Goldstein, M. L.; Figueroa-Viñas, A.; Blanco-Cano, X.

2014-05-01

335

Cyclotron masses and g -factors of hybridized electron-hole states in InAs/GaSb quantum wells  

NASA Astrophysics Data System (ADS)

Using the eight-band k•p model and the Burt-Foreman envelope function theory to perform self-consistent calculations, we have studied the effect of electron-hole hybridization on the cyclotron masses m* and the effective g -factors g* of two-dimensional quasiparticles in InAs/GaSb quantum wells under a magnetic field applied perpendicular to the interfaces. We can modify the degree of hybridization by changing the InAs and/or GaSb layer width, or by inserting a thin AlSb barrier. While electron-light-hole hybridization dominates at both low and high fields, due to a sequence of anticrossings between electronlike and heavy-holelike levels, there is also an important contribution from heavy-hole states to the strong hybridization in the intermediate field range. The field-dependence of the hybridized energy eigenstates is manifested in the variations of m* and g* . Characteristic discontinuous changes of both m* and g* appear at each anticrossing, resulting in a magnetic-field-driven oscillating behavior of these quantities for electronlike states of a given Landau level index. The electron g -factor can change sign when two eigenstates anticross. Hybridization of electron and hole states enhances the electron effective mass, and we have found a complicated dependence of this effect on the interaction strength. Without inserting an AlSb barrier, the strong interaction between the electronlike and the light-holelike states at low magnetic fields produces a large level repulsion, and hence relatively small effective masses and g -factors associated with these states. Intermediate interaction leads to weaker level repulsion and therefore very heavy electron cyclotron masses as well as large g -factors associated with the lowest Landau levels. A weak interaction only enhances the cyclotron masses of the electronlike states slightly. The hole effective masses change with both the magnetic field and the sample structure in a more complicated fashion.

Nilsson, K.; Zakharova, A.; Lapushkin, I.; Yen, S. T.; Chao, K. A.

2006-08-01

336

The new bern PET cyclotron, its research beam line, and the development of an innovative beam monitor detector  

SciTech Connect

The new Bern cyclotron laboratory aims at industrial radioisotope production for PET diagnostics and multidisciplinary research by means of a specifically conceived beam transfer line, terminated in a separate bunker. In this framework, an innovative beam monitor detector based on doped silica and optical fibres has been designed, constructed, and tested. Scintillation light produced by Ce and Sb doped silica fibres moving across the beam is measured, giving information on beam position, shape, and intensity. The doped fibres are coupled to commercial optical fibres, allowing the read-out of the signal far away from the radiation source. This general-purpose device can be easily adapted for any accelerator used in medical applications and is suitable either for low currents used in hadrontherapy or for currents up to a few {mu}A for radioisotope production, as well as for both pulsed and continuous beams.

Braccini, Saverio [Albert Einstein Center for Fundamental Physics, Laboratory for High Energy Physics (LHEP), University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland)

2013-04-19

337

First commissioning results with the Grenoble test electron cyclotron resonance ion source at iThemba LABSa)  

NASA Astrophysics Data System (ADS)

iThemba Laboratory for Accelerator Based Science (iThemba LABS) is a multi-disciplinary accelerator facility. One of its main activities is the operation of a separated-sector cyclotron with a K-value of 200, which provides beams of various ion species. These beams are used for fundamental nuclear physics research in the intermediate energy region, radioisotope production, and medical physics applications. Due to the requirements of nuclear physics for new ion species and higher energies, the decision was made to install a copy of the so-called Grenoble test source (GTS) at iThemba LABS. In this paper, we will report on the experimental setup and the first results obtained with the GTS2 at iThemba LABS.

Thomae, R.; Conradie, J.; Delsink, H.; Du Plessis, H.; Fourie, D.; Hitz, D.; Klopp, M.; Kohler, I.; Kuechler, D.; Lussi, C.; McAlister, R.; Ntshangase, S.; Sakildien, M.

2012-02-01

338

The new bern PET cyclotron, its research beam line, and the development of an innovative beam monitor detector  

NASA Astrophysics Data System (ADS)

The new Bern cyclotron laboratory aims at industrial radioisotope production for PET diagnostics and multidisciplinary research by means of a specifically conceived beam transfer line, terminated in a separate bunker. In this framework, an innovative beam monitor detector based on doped silica and optical fibres has been designed, constructed, and tested. Scintillation light produced by Ce and Sb doped silica fibres moving across the beam is measured, giving information on beam position, shape, and intensity. The doped fibres are coupled to commercial optical fibres, allowing the read-out of the signal far away from the radiation source. This general-purpose device can be easily adapted for any accelerator used in medical applications and is suitable either for low currents used in hadrontherapy or for currents up to a few ?A for radioisotope production, as well as for both pulsed and continuous beams.

Braccini, Saverio

2013-04-01

339

The compact electron cyclotron resonance ion source KeiGM for the carbon ion therapy facility at Gunma University.  

PubMed

A high-energy carbon-ion radiotherapy facility is under construction at Gunma University Heavy Ion Medical Centre (GHMC). Its design was based on a study of the heavy ion radiotherapy at the National Institute of Radiological Sciences (NIRS) in order to reduce the size and construction cost of the facility. A compact electron cyclotron resonance ion source (ECRIS) for Gunma University, called KeiGM, was installed in 2008. It is almost a copy of the prototype ECRIS Kei2 which was developed by NIRS; meanwhile this prototype produced over 1 e mA of C(4+) using C(2)H(2) gas (660 W and 40 kV). The beam intensity of C(4+) was 600 e microA with CH(4) gas (250 W and 30 kV). The beam intensity satisfies the required value of 300 e microA. PMID:20192348

Muramatsu, M; Kitagawa, A; Drentje, A G; Hojo, S; Ueda, T; Miyazaki, H; Yusa, K; Tashiro, M; Torikai, K; Sakama, M; Kanai, T; Yamada, S

2010-02-01

340

First commissioning results with the Grenoble test electron cyclotron resonance ion source at iThemba LABS.  

PubMed

iThemba Laboratory for Accelerator Based Science (iThemba LABS) is a multi-disciplinary accelerator facility. One of its main activities is the operation of a separated-sector cyclotron with a K-value of 200, which provides beams of various ion species. These beams are used for fundamental nuclear physics research in the intermediate energy region, radioisotope production, and medical physics applications. Due to the requirements of nuclear physics for new ion species and higher energies, the decision was made to install a copy of the so-called Grenoble test source (GTS) at iThemba LABS. In this paper, we will report on the experimental setup and the first results obtained with the GTS2 at iThemba LABS. PMID:22380170

Thomae, R; Conradie, J; Delsink, H; Du Plessis, H; Fourie, D; Hitz, D; Klopp, M; Kohler, I; Kuechler, D; Lussi, C; McAlister, R; Ntshangase, S; Sakildien, M

2012-02-01

341

Small Bowel Transplant  

PubMed Central

EXECUTIVE SUMMARY Objective The Medical Advisory Secretariat undertook a review of the evidence on the effectiveness and cost-effectiveness of small bowel transplant in the treatment of intestinal failure. Small Bowel Transplantation Intestinal failure is the loss of absorptive capacity of the small intestine that results in an inability to meet the nutrient and fluid requirements of the body via the enteral route. Patients with intestinal failure usually receive nutrients intravenously, a procedure known as parenteral nutrition. However, long-term parenteral nutrition is associated with complications including liver failure and loss of venous access due to recurrent infections. Small bowel transplant is the transplantation of a cadaveric intestinal allograft for the purpose of restoring intestinal function in patients with irreversible intestinal failure. The transplant may involve the small intestine alone (isolated small bowel ISB), the small intestine and the liver (SB-L) when there is irreversible liver failure, or multiple organs including the small bowel (multivisceral MV or cluster). Although living related donor transplant is being investigated at a limited number of centres, cadaveric donors have been used in most small bowel transplants. The actual transplant procedure takes approximately 12-18 hours. After intestinal transplant, the patient is generally placed on prophylactic antibiotic medication and immunosuppressive regimen that, in the majority of cases, would include tacrolimus, corticosteroids and an induction agent. Close monitoring for infection and rejection are essential for early treatment. Medical Advisory Secretariat Review The Medical Advisory Secretariat undertook a review of 35 reports from 9 case series and 1 international registry. Sample size of the individual studies ranged from 9 to 155. As of May 2001, 651 patients had received small bowel transplant procedures worldwide. According to information from the Canadian Organ Replacement Register, a total of 27 small bowel transplants were performed in Canada from 1988 to 2002. Patient Outcomes The experience in small bowel transplant is still limited. International data showed that during the last decade, patient survival and graft survival rates from SBT have improved, mainly because of improved immunosuppression therapy and earlier detection and treatment of infection and rejection. The Intestinal Transplant Registry reported 1-year actuarial patient survival rates of 69% for isolated small bowel transplant, 66% for small bowel-liver transplant, and 63% for multivisceral transplant, and a graft survival rate of 55% for ISB and 63% for SB-L and MV. The range of 1-year patient survival rates reported ranged from 33%-87%. Reported 1-year graft survival rates ranged from 46-71%. Regression analysis performed by the International Transplant Registry in 1997 indicated that centres that have performed at least 10 small bowel transplants had better patient and graft survival rates than centres that performed less than 10 transplants. However, analysis of the data up to May 2001 suggests that the critical mass of 10 transplants no longer holds true for transplants after 1995, and that good results can be achieved at any multiorgan transplant program with moderate patient volumes. The largest Centre reported an overall 1-year patient and graft survival rate of 72% and 64% respectively, and 5-year patient and graft survival of 48% and 40% respectively. The overall 1-year patient survival rate reported for Ontario pediatric small bowel transplants was 61% with the highest survival rate of 83% for ISB. The majority (70% or higher) of surviving small bowel transplant recipients was able to wean from parenteral nutrition and meet all caloric needs enterally. Some may need enteral or parenteral supplementation during periods of illness. Growth and weight gain in children after ISB were reported by two studies while two other studies reported a decrease in growth velocity with no catch-up growth. The quality of life after SBT was reported to be comparable t

2003-01-01

342

Simulation of Electromagnetic Ion Cyclotron Waves in Dipole Field  

NASA Astrophysics Data System (ADS)

The Electromagnetic Ion Cyclotron (EMIC) wave is commonly observed in the Earth's magnetosphere. It is believed to be excited when a large number of particles are injected into the dusk side of the magnetosphere during substorms. Theoretical works have suggested that EMIC waves may contribute significantly to Relativistic Electron Precipitation (REP) by pitch-angle scattering. REP events are one of the important aspect of the radiation belt dynamics. We will be using a hybrid code simulation to study EMIC waves in inhomogenuous dipole magnetic field, including instability, wave propagation, and wave-particle interaction. Up to date results will be shown in this poster.

Hu, Y.; Denton, R.

2008-05-01

343

Study of Electromagnetic Ion Cyclotron Instability in Dipole Geometry  

NASA Astrophysics Data System (ADS)

The Electromagnetic Ion Cyclotron (EMIC) wave is commonly observed in the Earth's magnetosphere. It is believed to be excited when a large number of particles are injected into the dusk side of the magnetosphere during substorms. Theoretical works have suggested that EMIC waves may contribute significantly to Relativistic Electron Precipitation (REP) by pitch-angle scattering. REP events are one of the important aspect of the radiation belt dynamics. We will be using a hybrid code simulation to study EMIC waves in dipole geometry, including instability, wave propagation, and wave-particle interaction. Up to date results will be shown in this poster.

Hu, Y.; Denton, R.

2007-12-01

344

Twisted electrostatic ion-cyclotron waves in dusty plasmas.  

PubMed

We show the existence of a twisted electrostatic ion-cyclotron (ESIC) wave carrying orbital angular momentum (OAM) in a magnetized dusty plasma. For our purposes, we derive a 3D wave equation for the coupled ESIC and dust ion-acoustic (DIA) waves from the hydrodynamic equations that are composed of the continuity and momentum equations, together with Poisson's equation. The 3D wave equation reveals the formation of a braided or twisted ESIC wave structure carrying OAM. The braided or twisted ESIC wave structure can trap and transport plasma particles in magnetoplasmas, such as those in Saturn's F-ring and in the forthcoming magnetized dusty plasma experiments. PMID:23410477

Shukla, P K

2013-01-01

345

Ion cyclotron resonance heated conics: Theory and observations  

SciTech Connect

A general theoretical treatment of energetic oxygen ion conic formation through cyclotron resonance with magnetospheric electromagnetic plasma turbulence is presented. With suitable assumptions, there exists a similarity regime in which the process may be profitably characterized by two parameters v{sub o} and {sigma}, corresponding roughly to the velocity scale and pitch angle of the ion distribution. These may be independently determined from the wave and particle observations of a conic event, as is illustrated here using typical auroral passes of the Dynamics Explorer 1 satellite. The predictions of the theory are found to be in excellent agreement with the observations.

Crew, G.B.; Chang, T.; Retterer, J.M. (Massachusetts Inst. of Tech., Cambridge, MA (United States)); Peterson, W.K. (Lockhead Palo Alto Research Lab., CA (United States)); Gurnett, D.A.; Huff, R.L. (Univ. of Iowa, Iowa City (United States))

1990-04-01

346

Ion cyclotron resonance heated conics - Theory and observations  

NASA Technical Reports Server (NTRS)

A general theoretical treatment of energetic oxygen ion conic formation through cyclotron resonance with magnetospheric electromagnetic plasma turbulence is presented. With suitable assumptions, there exists a similarity regime in which the process may be profitably characterized by two parameters corresponding roughly to the velocity scale and pitch angle of the ion distribution. These may be independently determined from the wave and particle observations of a conic event, as is illustrated here using typical auroral passes of the Dynamics Explorer 1 satellite. The predictions of the theory are found to be in excellent agreement with the observations.

Crew, G. B.; Chang, Tom; Retterer, J. M.; Peterson, W. K.; Gurnett, D. A.

1990-01-01

347

Ion-cyclotron-resonance-heated conics: Theory and observations  

SciTech Connect

A general theoretical treatment of energetic oxygen ion conic formation through cyclotron resonance with magnetospheric electromagnetic plasma turbulence is presented. With suitable assumptions, there exists a similarity regime in which the process may be profitably characterized by two parameters corresponding roughly to the velocity scale and pitch angle of the ion distribution. These may be independently determined from the wave and particle observations of a conic event, as is illustrated here using typical auroral passes of the Dynamics Explorer 1 satellite. The predictions of the theory are found to be in excellent agreement with the observations.

Crew, G.B.; Chang, T.; Retterer, J.M.; Peterson, W.K.; Gurnett, D.A.

1990-04-01

348

Asymmetric spectral broadening of modulated electrostatic ion-cyclotron waves  

SciTech Connect

Modulated, current-driven, electrostatic ion-cyclotron (CDEIC) waves are shown to exhibit amplitude and frequency modulation, spectral broadening, and time-averaged frequency pulling. The observed spectral broadening is asymmetric and sensitively dependent on the driving frequency. Qualitative features of the experimental data are reproduced by the forced van der Pol equation and are explainable using processes associated with driven self oscillations. These results may be relevant to ionospheric modification experiments involving the controlled modulation of the natural electrojet. 31 refs., 4 figs.

Koepke, M.E.; Alport, M.J.; Sheridan, T.E.; Amatucci, W.E.; Carroll, J.J. III [West Virginia Univ., Morgantown, WV (United States)] [West Virginia Univ., Morgantown, WV (United States)

1994-06-01

349

Cyclotron line resonant transfer through neutron star atmospheres  

NASA Technical Reports Server (NTRS)

Monte Carlo methods are used to study in detail the resonant radiative transfer of cyclotron line photons with recoil through a purely scattering neutron star atmosphere for both the polarized and unpolarized cases. For each case, the number of scatters, the path length traveled, the escape frequency shift, the escape direction cosine, the emergent frequency spectra, and the angular distribution of escaping photons are investigated. In the polarized case, transfer is calculated using both the cold plasma e- and o-modes and the magnetic vacuum perpendicular and parallel modes.

Wang, John C. L.; Wasserman, Ira M.; Salpeter, Edwin E.

1988-01-01

350

Initiative in Nuclear Theory at the Variable Energy Cyclotron Centre  

E-print Network

We recall the path breaking contributions of the nuclear theory group of the Variable Energy Cyclotron Centre, Kolkata. From a beginning of just one person in 1970s, the group has steadily developed into a leading group in the country today, with seminal contributions to almost the entire range of nuclear physics, viz., low energy nuclear reactions, nuclear structure, deep inelastic collisions, fission, liquid to gas phase transitions, nuclear matter, equation of state, mass formulae, neutron stars, relativistic heavy ion collisions, medium modification of hadron properties, quark gluon plasma, and cosmology of early universe.

D. K. Srivastava; J. Alam; D. N. Basu; A. K. Chaudhuri; J. N. De; K. Krishan; S. Pal

2005-06-24

351

High-frequency fourier transform ion cyclotron resonance mass spectrometry.  

PubMed

The experimental Fourier transform ion cyclotron resonance (FT/ICR) frequency range has been extended to 107 MHz. We report the observation of FT/ICR signals from electron-ionized species of mass-to-charge ratio 8, 7, 6, 5, 4, 3, 2, and 1 ? per elementary charge. We show that moderately high charge states of atomic ions (e.g., N(3+)) are easily generated and detected. Several applications for high-frequency FT/ICR mass spectrometry are proposed and discussed. PMID:24234797

Schweikhard, L; Alber, G M; Marshall, A G

1993-02-01

352

Experimental monitoring of ozone production in a PET cyclotron facility.  

PubMed

Ozone produced from radiolytic processes was investigated as a possible health hazard in the working environment at the University Hospital "S.Orsola--Malpighi" PET facility. Intense radiation fields can generate ozone, known to be the most toxic gas produced by ionizing radiation around a particle accelerator. To evaluate ozone concentration in air, two different measurement campaigns were conducted with passive diffusion detectors. Comparison of the results with the concentration limits recommended by American Conference of Governmental Industrial Hygienists (ACGIH) demonstrated that ozone poses no health hazard to workers around a biomedical cyclotron. PMID:20483623

Zanibellato, L; Cicoria, G; Pancaldi, D; Boschi, S; Mostacci, D; Marengo, M

2010-10-01

353

Potential applications of an electron cyclotron resonance multicusp plasma source  

SciTech Connect

An electron cyclotron resonance (ECR) multicusp plasmatron has been developed by feeding a multicusp bucket arc chamber with a compact ECR plasma source. This novel source produced large (about 25-cm-diam), uniform (to within {plus minus}10%), dense (>10{sup 11}-cm{sup -3}) plasmas of argon, helium, hydrogen, and oxygen. It has been operated to produce an oxygen plasma for etching 12.7-cm (5-in.) positive photoresist-coated silicon wafers with uniformity within {plus minus}8%. Results and potential applications of this new ECR plasma source for plasma processing of thin films are discussed. 21 refs., 10 figs.

Tsai, C.C.; Berry, L.A.; Gorbatkin, S.M.; Haselton, H.H.; Roberto, J.B.; Stirling, W.L.

1989-01-01

354

Use of electron cyclotron resonance x-ray source for nondestructive testing application  

SciTech Connect

Electron cyclotron resonance (ECR) technique is being used for generating x rays in the low-energy region (<150 keV). Recently, the source is used for the calibration of thermoluminescent dosimetry (TLD) badges. In order to qualify the ECR x-ray source for imaging application, the source should give uniform flux over the area under study. Lead collimation arrangement is made to get uniform flux. The flux profile is measured using a teletector at different distance from the port and uniform field region of 10x10 cm{sup 2} has been marked at 20 cm from the x-ray exit port. A digital-to-analog converter (DAC) circuit pack is used for examining the source performance. The required dose for nondestructive testing examination has been estimated using a hospital x-ray machine and it is found to be 0.05 mSv. Our source experimental parameters are tuned and the DAC circuit pack was exposed for nearly 7 min to get the required dose value. The ECR x-ray source operating parameters are argon pressure: 10{sup -5} Torr, microwave power: 350 W, and coil current: 0 A. The effective energy of the x-ray spectrum is nearly 40 keV. The x-ray images obtained from ECR x-ray source and hospital medical radiography machine are compared. It is found that the image obtained from ECR x-ray source is suitable for NDT application.

Baskaran, R.; Selvakumaran, T.S. [Radiological Safety Division, Safety Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India)

2006-03-15

355

Fast earthward flows, electron cyclotron harmonic waves, and diffuse auroras: Conjunctive observations  

E-print Network

Fast earthward flows, electron cyclotron harmonic waves, and diffuse auroras: Conjunctive of fast earthward flows, electrostatic electron cyclotron harmonic (ECH) waves, and diffuse auroras a causal conjunction between the ECH waves and diffuse auroras for the reported event. We also propose

California at Berkeley, University of

356

SPITZER IRS SPECTROSCOPY OF INTERMEDIATE POLARS: CONSTRAINTS ON MID-INFRARED CYCLOTRON EMISSION  

E-print Network

, and possibly EX Hya and V1223 Sgr, do show longer wavelength excesses. We have used a cyclotron modeling code with cyclotron emission from a 1 MG field, but the S/N of those data is very poor, and the reality of those, TV Columbae, TX Columbae, V603 Aquilae, V1223 Sagitarii) 1. INTRODUCTION Intermediate polars (IPs

Harrison, Thomas

357

Electron cyclotron maser based on the combination two-wave resonance  

SciTech Connect

A mechanism of a combination two-wave cyclotron interaction between an electron beam and the forward/backward components of a far-from-cutoff standing wave is analyzed. This regime can be promising for the realization of high-power continuous-wave electron cyclotron masers operating in the THz frequency range.

Savilov, A. V. [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod (Russian Federation) and Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod (Russian Federation)

2012-11-01

358

Production of exotic beams at the LBL 88-Inch Cyclotron by the ISOL method.  

National Technical Information Service (NTIS)

The Users of the LBL 88-Inch Cyclotron are preparing a proposal to produce exotic, i.e., radioactive beams. The facility will consist of a high-current 30 MeV cyclotron to generate the radioactive nuclei, an ECR source that can be coupled to different pro...

1990-01-01

359

Ultrahigh magnetic field cyclotron resonance of zero-gap InAs\\/GaSb superlattices  

Microsoft Academic Search

Ultra-high magnetic field (<150T) cyclotron resonance has been studied in superlattices of InAs\\/GaSb with band gaps close to zero where the effects of conduction and valence bands are enhanced. Several samples exhibit a low-field structure associated with the N=2 and 4 harmonics of the cyclotron resonance. The interband transition data is also shown.

D. J. Barnes; R. J. Nicholas; N. J. Mason; P. J. Walker; R. J. Warburton; N. Miura

1993-01-01

360

76 FR 80982 - International Cyclotron, Inc., Hato Rey, Puerto Rico; Order Suspending Licensed Activities  

Federal Register 2010, 2011, 2012, 2013

...to decommission its facilities, and is to ensure that...decommissioning of licensed facilities is in place in the event...When International Cyclotron submitted its NRC license...over the life of the facility; 4. A certification...f). International Cyclotron failed to submit...

2011-12-27

361

Medical Myth Prevention - Understanding Medical News  

MedlinePLUS

... H. Shmerling, M.D. is associate physician at Beth Israel Deaconess Medical Center and associate professor at Harvard Medical ... a practicing rheumatologist for over 20 years at Beth Israel Deaconess Medical Center. He is an active teacher in ...

362

Smoking cessation medications  

MedlinePLUS

Smoking cessation - medications; Smokeless tobacco - medications; Medications for stopping tobacco ... Creating a plan to help you deal with smoking urges. Getting support from a doctor, counselor, or ...

363

How do we Define a Medical School?  

PubMed Central

A century after the Flexner Report on medical education in North America, which revolutionised the training of medical doctors all over the world, it is time to revisit this famous document and analyse symptoms and signs of a return to pre-Flexnerian conditions. With the ongoing mushroom growth over the last decades of small, proprietary educational institutions of low quality and driven by for-profit purposes, medical education is in a threatened position. This trend is of general international interest because of the increasing migration of medical doctors. There is a need for discussion of what should be the rational criteria and basic requirements for establishing new medical schools. PMID:21509225

Karle, Hans

2010-01-01

364

Medical errors in neurosurgery  

PubMed Central

Background: Medical errors cause nearly 100,000 deaths per year and cost billions of dollars annually. In order to rationally develop and institute programs to mitigate errors, the relative frequency and costs of different errors must be documented. This analysis will permit the judicious allocation of scarce healthcare resources to address the most costly errors as they are identified. Methods: Here, we provide a systematic review of the neurosurgical literature describing medical errors at the departmental level. Eligible articles were identified from the PubMed database, and restricted to reports of recognizable errors across neurosurgical practices. We limited this analysis to cross-sectional studies of errors in order to better match systems-level concerns, rather than reviewing the literature for individually selected errors like wrong-sided or wrong-level surgery. Results: Only a small number of articles met these criteria, highlighting the paucity of data on this topic. From these studies, errors were documented in anywhere from 12% to 88.7% of cases. These errors had many sources, of which only 23.7-27.8% were technical, related to the execution of the surgery itself, highlighting the importance of systems-level approaches to protecting patients and reducing errors. Conclusions: Overall, the magnitude of medical errors in neurosurgery and the lack of focused research emphasize the need for prospective categorization of morbidity with judicious attribution. Ultimately, we must raise awareness of the impact of medical errors in neurosurgery, reduce the occurrence of medical errors, and mitigate their detrimental effects. PMID:25371849

Rolston, John D.; Zygourakis, Corinna C.; Han, Seunggu J.; Lau, Catherine Y.; Berger, Mitchel S.; Parsa, Andrew T.

2014-01-01

365

Nonlinear theory of drift-cyclotron kinetics and the possible breakdown of gyro-kinetics  

SciTech Connect

A nonlinear theory of drift-cyclotron kinetics (termed cyclo-kinetics here) is formulated to test the breakdown of the gyro-kinetic approximations. Six dimensional cyclo-kinetics can be regarded as an extension of five dimensional gyro-kinetics to include high-frequency cyclotron waves, which can interrupt the low-frequency gyro-averaging in the (sixth velocity grid) gyro-phase angle. Nonlinear cyclo-kinetics has no limit on the amplitude of the perturbations. Formally, there is no gyro-averaging when all cyclotron (gyro-phase angle) harmonics of the perturbed distribution function (delta-f) are retained. Retaining only the (low frequency) zeroth cyclotron harmonic in cyclo-kinetics recovers both linear and nonlinear gyro-kinetics. Simple recipes are given for converting continuum nonlinear delta-f gyro-kinetic transport simulation codes to cyclo-kinetics codes by retaining (at least some) higher cyclotron harmonics.

Waltz, R. E. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Deng Zhao [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China)

2013-01-15

366

Medical clip  

NASA Technical Reports Server (NTRS)

An X-ray transparent and biological inert medical clip for treating aneurisms and the like is described. A graphite reinforced composite film is molded into a unitary structure having a pair of hourglass-like cavities hinged together with a pair of jaws for grasping the aneurism extending from the wall of one cavity. A silicone rubber pellet is disposed in the other cavity to exert a spring force through the hinge area to normally bias the jaws into contact with each other.

Baucom, R. M. (inventor)

1983-01-01

367

Medical Mystery  

NSDL National Science Digital Library

This activity (on pages 15-23) combines interactive role-playing and graphing to introduce learners to the health affects of pollen. In the first part, learners role-play a detective on a medical case and the main character in the case. Learners formulate a hypothesis about a patient's illness. In the second part, learners graph evidence based on pollen counts and create a "final report" about what caused the patient's health problem. This activity smoothly combines health education, environmental science, and math.

Museum, University O.; Nebraska Cooperative Extension 4-H Youth Development

2001-01-01

368

Medical Physiology and Experimentation: Reconsidering the Undergraduate Examination Structure  

NSDL National Science Digital Library

Discussion of how evaluation of medical physiology should be to enhance a more active participation of the students in the small-group experimentation lectures taking place during the teaching of medical physiology

Dr. Stylianos Tsakiris (University of Athens Department of Experimental Physiology Medical School); Apostolos Zarros (University of Athens Department of Experimental Physiology Medical School)

2006-06-01

369

Stereotactic body radiotherapy for medically inoperable patients with stage I non-small cell lung cancer – A first report of toxicity related to COPD\\/CVD in a non-randomized prospective phase II study  

Microsoft Academic Search

Background and AimsIn a retrospective study using stereotactic body radiotherapy (SBRT) in medically inoperable patients with stage I NSCLC we previously reported a local control rate of 88% utilizing a median dose of 15Gy×3. This report records the toxicity encountered in a prospective phase II trial, and its relation to coexisting chronic obstructive pulmonary disease (COPD) and cardio vascular disease

Pia Baumann; Jan Nyman; Morten Hoyer; Giovanna Gagliardi; Ingmar Lax; Berit Wennberg; Ninni Drugge; Lars Ekberg; Signe Friesland; Karl-Axel Johansson; Jo-Åsmund Lund; Elisabeth Morhed; Kristina Nilsson; Nina Levin; Merete Paludan; Christer Sederholm; Anders Traberg; Lena Wittgren; Rolf Lewensohn

2008-01-01

370

Electronuclear ion fusion in an ion cyclotron resonance reactor  

SciTech Connect

A method and apparatus for generating nuclear fusion by ion cyclotron resonance in an ion trap reactor. The reactor includes a cylindrical housing having an axial axis, an internal surface, and first and second ends. First and second end plates that are charged are respectively located at the first and second ends of the cylindrical housing. A gas layer is adsorbed on the internal surface of the cylindrical housing. Ions are desorbed from the gas layer, forming a plasma layer adjacent to the cylindrical housing that includes first ions that have a same charge sign as the first and second end plates. A uniform magnetic field is oriented along the axial axis of the cylindrical housing. Second ions, that are unlike the first ions, but have the same charge sign, are injected into the cylindrical housing along the axial axis of the cylindrical housing. A radio frequency field resonantly accelerates the injected second ions at the cyclotron resonance frequency of the second ions. The second ions circulate in increasing helical orbits and react with the first ions, at the optimum energy for nuclear fusion. The amplitude of the radio frequency field is adjusted to accelerate the second ions at a rate equal to the rate of tangential energy loss of the second ions by nuclear scattering in the first ions, causing the ions to continually interact until fusion occurs.

Cowgill, Donald F.

1996-12-01

371

Thermal Cyclotron Absorption Coefficients. II. Opacities in the Stokes Formalism  

NASA Astrophysics Data System (ADS)

We extend the discussion of the calculation of the cyclotron opacities ?± of the ordinary and extraordinary mode (Chanmugam et al.) to the opacities ?, q, ? in the Stokes formalism. We derive formulae with which a can be calculated from ?, q, ?. We are hence able to compare our calculations of the opacities, which are based on the single-particle method, with results obtained with the dielectric tensor method of Tam or. Excellent agreement is achieved. We present extensive tables of the opacities in the Stokes formalism for frequencies up to 25?c, where ?c is the cyclotron frequency, and temperatures kT = 5, 10,20, 30,40, and 50 keV. Furthermore, we derive approximate formulae with which ?, q, ? can be calculated from ?± and hence use the Robinson & Melrose analytic formulae for ?± in order to calculate the opacities in the Stokes formalism. We compare these opacities to accurate numerical opacities and find that the analytic formulae can reproduce the qualitative behavior of the opacities in the regions where the harmonic structure is unimportant.

Vaeth, H. M.; Chanmugam, G.

1995-05-01

372

Vacuum system of the cyclotrons in VECC, Kolkata  

SciTech Connect

The vacuum system of the K=130 Room Temperature Cyclotron (RTC) (operational since 1978) has been recently modernized and the same of the K{sub bend}=520 Superconducting Cyclotron (SCC), currently under commissioning, is being deployed for remote monitoring and control. The vacuum system of RTC is designed to achieve and maintain vacuum level of 2 X 10{sup -6} mbar inside 23 m{sup 3} volume of Resonator tank and DEE tank. This has been upgraded by replacing several valves, Freon units, gauges and pumps. The relay based manual control system has been replaced by PLC based automated system. The SCC vacuum system also has an elaborate arrangement comprising of turbo molecular pumping modules with associated isolation valves and characteristic gauges. This paper describes essential elements, typically used to obtain high (1X10{sup -7} mbar) vacuum using rotary pumps, diffusion pumps and cold traps/turbo-molecular pumps and other system components such as valves, gauges and baffles. The supervisory control methodology/scheme of both the vacuum systems, developed in-house using EPICS (Experimental Physics and Industrial Control System), a standard open-source software tool for designing distributed control system, is also elaborated here. (author)

Roy, Anindya; Bhole, R.B.; Akhtar, J.; Yadav, R.C.; Pal, Sarbajit; Sarkar, D.; Bhandari, R.K., E-mail: r_ani@vecc.gov.in, E-mail: rbb@vecc.gov.in, E-mail: javed@vecc.gov.in, E-mail: yadav@vecc.gov.in, E-mail: sarbajit@vecc.gov.in, E-mail: dsarkar@vecc.gov.in, E-mail: bhandari@vecc.gov.in [Variable Energy Cyclotron Centre, Kolkata (India)

2011-07-01

373

Plasma-Sheath Instability in Hall Thrusters Due to Periodic Modulation of the Energy of Secondary Electrons in Cyclotron Motion  

SciTech Connect

Particle-in-cell simulation of Hall thruster plasmas reveals a plasma-sheath instability manifesting itself as a rearrangement of the plasma sheath near the thruster channel walls accompanied by a sudden change of many discharge parameters. The instability develops when the sheath current as a function of the sheath voltage is in the negative conductivity regime. The major part of the sheath current is produced by beams of secondary electrons counter-streaming between the walls. The negative conductivity is the result of nonlinear dependence of beam-induced secondary electron emission on the plasma potential. The intensity of such emission is defined by the beam energy. The energy of the beam in crossed axial electric and radial magnetic fields is a quasi-periodical function of the phase of cyclotron rotation, which depends on the radial profile of the potential and the thruster channel width. There is a discrete set of stability intervals determined by the final phase of the cyclotron rotation of secondary electrons. As a result, a small variation of the thruster channel width may result in abrupt changes of plasma parameters if the plasma state jumps from one stability interval to another.

D. Sydorenko and A. Smolyakov I. Kaganovich and Y. Raitses

2008-04-23

374

COMPLETE SUPPRESSION OF THE M=2/N-1 NEOCLASSICAL TEARING MODE USING ELECTRON CYCLOTRON CURRENT DRIVE ON DIII-D  

SciTech Connect

A271 COMPLETE SUPPRESSION OF THE M=2/N-1 NEOCLASSICAL TEARING MODE USING ELECTRON CYCLOTRON CURRENT DRIVE ON DIII-D. The first suppression of the important and deleterious m=2/n=1 neoclassical tearing mode (NTM) is reported using electron cyclotron current drive (ECCD) to replace the ''missing'' bootstrap current in the island O-point. Experiments on the DIII-D tokamak verify the maximum shrinkage of the m=2/n=1 island occurs when the ECCD location coincides with the q = 2 surface. The DIII-D plasma control system is put into search and suppress mode to make small changes in the toroidal field to find and lock onto the optimum position, based on real time measurements of dB{sub {theta}}/dt, for complete m=2/n=1 NTM suppression by ECCD. The requirements on the ECCD for complete island suppression are well modeled by the modified Rutherford equation for the DIII-D plasma conditions.

PETTY,CC; LAHAYE,LA; LUCE,TC; HUMPHREYS,DA; HYATT,AW; PRATER,R; STRAIT,EJ; WADE,MR

2003-03-01

375

Appearance and dynamics of helical flux tubes under electron cyclotron resonance heating in the core of KSTAR plasmas.  

PubMed

Dual (or sometimes multiple) flux tubes (DFTs) have been observed in the core of sawtoothing KSTAR tokamak plasmas with electron cyclotron resonance heating. The time evolution of the flux tubes visualized by a 2D electron cyclotron emission imaging diagnostic typically consists of four distinctive phases: (1) growth of one flux tube out of multiple small flux tubes during the initial buildup period following a sawtooth crash, resulting in a single dominant flux tube along the m/n=1/1 helical magnetic field lines, (2) sudden rapid growth of another flux tube via a fast heat transfer from the first one, resulting in approximately identical DFTs, (3) coalescence of the two flux tubes into a single m/n=1/1 flux tube resembling the internal kink mode in the normal sawteeth, which is explained by a model of two current-carrying wires confined on a flux surface, and (4) fast localized crash of the merged flux tube similar to the standard sawtooth crash. The dynamics of the DFTs implies that the internal kink mode is not a unique prerequisite to the sawtooth crash, providing a new insight on the control of the sawtooth. PMID:23083252

Yun, G S; Park, H K; Lee, W; Choi, M J; Choe, G H; Park, S; Bae, Y S; Lee, K D; Yoon, S W; Jeon, Y M; Domier, C W; Luhmann, N C; Tobias, B; Donné, A J H

2012-10-01

376

Medical Misuse of Controlled Medications Among Adolescents  

PubMed Central

Objectives To determine the past-year medical misuse prevalence for 4 controlled medication classes (pain, stimulant, sleeping, and antianxiety) among adolescents, and to assess substance use outcomes among adolescents who report medical misuse. Design A Web-based survey was self-administered by 2744 secondary school students in 2009-2010. Setting Two southeastern Michigan school districts. Participants The sample had a mean age of 14.8 years and was 51.1% female. The racial/ethnic distribution was 65.0% white, 29.5% African American, 3.7% Asian, 1.3% Hispanic, and 0.5% other. Main Outcome Measures Past-year medical use and misuse of 4 controlled medication classes. Results Eighteen percent of the sample reported past-year medical use of at least 1 prescribed controlled medication. Among past-year medical users, 22.0% reported misuse of their controlled medications, including taking too much, intentionally getting high, or using to increase alcohol or other drug effects. Medical misusers were more likely than nonmisusers to divert their controlled medications and to abuse other substances. The odds of a positive screening result for drug abuse were substantially higher among medical misusers (adjusted odds ratio, 7.8; 95% confidence interval, 4.3-14.2) compared with medical users who used their controlled medications appropriately. The odds of drug abuse did not differ between medical users who used their controlled medications appropriately and nonusers. Conclusions Most adolescents who used controlled medications took their medications appropriately. Substance use and diversion of controlled medications were more prevalent among adolescents who misused their controlled medications. Careful therapeutic monitoring could reduce medical misuse and diversion of controlled medications among adolescents. PMID:21810634

McCabe, Sean Esteban; West, Brady T.; Cranford, James A.; Ross-Durow, Paula; Young, Amy; Teter, Christian J.; Boyd, Carol J.

2011-01-01

377

Medical responsibility.  

PubMed

These comments seek to take issue with the contention that society has a responsibility to provide its members with any needed health care. In order to deal with this claim we must first make clear exactly what it meant by the proposition. I take it that those who embrace this view mean considerably more than that each of us has a moral obligation to contribute to those in need of medical attention who are unable, for one reason or another, to afford the necessary care. This is a moral proposition and is traditionally dealt with under the heading of charity. But the contention, as here used, means considerably more since its main implications are not moral but primarily political. PMID:23061581

Hamowy, Ronald

2012-01-01

378

Medical marijuana.  

PubMed

Grassroots AIDS activist groups denounce the Clinton Administration's stance on banning medicinal use of marijuana due to the lack of clinical evidence supporting its benefits. The 1997 meeting of the San Francisco Medical Society and the New England Journal of Medicine both agreed, following a review of 75 scientific studies of the medicinal benefits of marijuana, that the benefits of smoked marijuana include relief from pain and the reduction of nausea caused by anti-cancer drugs. The Federal government is attempting to punish physicians for prescribing marijuana to their patients, a situation being opposed by the Bay Area Physicians for Human Rights who have initiated a suit against the government. A hearing to stop this prosecution was scheduled for March 21. PMID:11364533

Baker, R; Bowers, M

1997-03-01

379

Acquisition of medical device start-ups  

E-print Network

Introduction: In the medical device space, a large proportion of the breakthrough inventions are developed by small firms that use private equity to bring their technologies from concept to varying stages of development. ...

Nair, Ganesh R

2006-01-01

380

MEDICAL EMERGENCIES What is a medical emergency?  

E-print Network

MEDICAL EMERGENCIES What is a medical emergency? Serious injury or illness. What do I do if there is a medical emergency occurring or one has occurred? CALL 911. Paramedics and ambulance service or visitor. What information do I need to have readily available when reporting a medical emergency

Fernandez, Eduardo

381

MEDICAL EMERGENCIES What is a medical emergency?  

E-print Network

MEDICAL EMERGENCIES What is a medical emergency? Serious injury or illness. What do I do if there is a medical emergency occurring or one has occurred? NOTIFY 911 or University Police. Paramedics and ambulance, the employee to the nearest medical facility or CALL 911 for emergency assistance CALL OptaComp at 877

Fernandez, Eduardo

382

MEDICAL EMERGENCIES What is a medical emergency?  

E-print Network

MEDICAL EMERGENCIES What is a medical emergency? Serious injury or illness. What do I do if there is a medical emergency occurring or one has occurred? CALL 911. Paramedics and ambulance service or visitor. What information do I need to have readily available when reporting a medical emergency? Building

Fernandez, Eduardo

383

77 FR 31143 - Emergency Medical Services Week, 2012  

Federal Register 2010, 2011, 2012, 2013

...Proclamation 8824--Emergency Medical Services Week, 2012 Proclamation 8825--National Safe Boating Week, 2012 Proclamation 8826--National Small Business Week, 2012 Proclamation 8827--World Trade Week, 2012...

2012-05-24

384

Reduction of Axial Kinetic Energy Induced Perturbations on Observed Cyclotron Frequency  

PubMed Central

With Fourier Transform Ion Cyclotron Resonance (FTICR) mass spectrometry one determines the mass-to-charge ratio of an ion by measuring its cyclotron frequency. However, the need to confine ions to the trapping region of the ICR cell with electric fields induces deviations from the unperturbed cyclotron frequency. Additional perturbations to the observed cyclotron frequency are often attributed to changes in space charge conditions. This study presents a detailed investigation of the observed ion cyclotron frequency as a function of ion z-axis kinetic energy. In a perfect three-dimensional quadrupolar field, cyclotron frequency is independent of position within the trap. However, in most ICR cell designs, this ideality is approximated only near the trap center and deviations arise from this ideal quadrupolar field as the ion moves both radially and axially from the center of the trap. To allow differentiation between deviations in observed cyclotron frequency caused from changes in space charge conditions or differences in oscillation amplitude, ions with identical molecular weights but different axial kinetic energy, and therefore, amplitude of z-axis motion, were simultaneously trapped within the ICR cell. This allows one to attribute deviations in observed cyclotron frequency to differences in the average force from the radial electric field experienced by ions of different axial amplitude. Experimentally derived magnetron frequency is compared with the magnetron frequency calculated using SIMION 7.0 for ions of different axial amplitude. Electron Promoted Ion Coherence, or EPIC, is used to reduce the differences in radial electric fields at different axial positions. Thus with the application of EPIC, the differences in observed cyclotron frequencies are minimized for ions of different axial oscillation amplitudes. PMID:18262433

Kaiser, Nathan K.; Weisbrod, Chad R.; Webb, Brian N.; Bruce, James E.

2008-01-01

385

Medical schools in sub-Saharan Africa.  

PubMed

Small numbers of graduates from few medical schools, and emigration of graduates to other countries, contribute to low physician presence in sub-Saharan Africa. The Sub-Saharan African Medical School Study examined the challenges, innovations, and emerging trends in medical education in the region. We identified 168 medical schools; of the 146 surveyed, 105 (72%) responded. Findings from the study showed that countries are prioritising medical education scale-up as part of health-system strengthening, and we identified many innovations in premedical preparation, team-based education, and creative use of scarce research support. The study also drew attention to ubiquitous faculty shortages in basic and clinical sciences, weak physical infrastructure, and little use of external accreditation. Patterns recorded include the growth of private medical schools, community-based education, and international partnerships, and the benefit of research for faculty development. Ten recommendations provide guidance for efforts to strengthen medical education in sub-Saharan Africa. PMID:21074256

Mullan, Fitzhugh; Frehywot, Seble; Omaswa, Francis; Buch, Eric; Chen, Candice; Greysen, S Ryan; Wassermann, Travis; Abubakr, Diaa ElDin ElGaili; Awases, Magda; Boelen, Charles; Diomande, Mohenou Jean-Marie Isidore; Dovlo, Delanyo; Ferro, Josefo; Haileamlak, Abraham; Iputo, Jehu; Jacobs, Marian; Koumaré, Abdel Karim; Mipando, Mwapatsa; Monekosso, Gottleib Lobe; Olapade-Olaopa, Emiola Oluwabunmi; Rugarabamu, Paschalis; Sewankambo, Nelson K; Ross, Heather; Ayas, Huda; Chale, Selam Bedada; Cyprien, Soeurette; Cohen, Jordan; Haile-Mariam, Tenagne; Hamburger, Ellen; Jolley, Laura; Kolars, Joseph C; Kombe, Gilbert; Neusy, Andre-Jacques

2011-03-26

386

COMPUTER SIMULATIONS OF THE BEAM DYNAMICS IN THE SMALL ISOCHRONOUS RING  

Microsoft Academic Search

A Small Isochronous Ring (SIR), whose main objective is the experimental study of the space charge effects in the isochronous regime, is under development at the National Superconducting Cyclotron Laboratory (NSCL) at Michi- gan State University (MSU). To study the beam dynam- ics in the ring we tracked particle trajectories in a realis- tic magnetic field generated by Tosca. The

E. Pozdeyev; J. Rodriguez

2002-01-01

387

Nonresonant interaction of heavy ions with electromagnetic ion cyclotron waves  

NASA Technical Reports Server (NTRS)

The motion of a heavy ion in the presence of an intense ultralow-frequency electromagnetic wave propagating along the dc magnetic field is analyzed. Starting from the basic equations of motion and from their associated two invariants, the heavy ion velocity-space trajectories are drawn. It is shown that after a certain time, particles whose initial phase angles are randomly distributed tend to bunch together, provided that the wave intensity b-sub-1 is sufficiently large. The importance of these results for the interpretation of the recently observed acceleration of singly charged He ions in conjunction with the occurrence of large-amplitude ion cyclotron waves in the equatorial magnetosphere is discussed.

Berchem, J.; Gendrin, R.

1985-01-01

388

Grating monochromator for electron cyclotron resonance ion source operation  

SciTech Connect

Recently, we started to observe optical line spectra from an ECR plasma using a grating monochromator with a photomultiplier. The light intensity of line spectrum from the ECR plasma had a strong correlation with ion beam intensity measured by a magnetic mass analyzer. This correlation is a significant information for beam tuning because it allows the extraction of the desired ion species from the ECR plasma. Separation of ion species of the same charge to mass ratio with an electromagnetic mass analyzer is known to be an exceptionally complex process, but this research gives new insights into its simplification. In this paper, the grating monochromator method for beam tuning of a Hyper-ECR ion source as an injector for RIKEN azimuthal varying field (AVF) cyclotron is described.

Muto, Hideshi [Center of General Education, Tokyo University of Science, Suwa, 5000-1 Toyohira, Chino Nagano 391-0292 (Japan)] [Center of General Education, Tokyo University of Science, Suwa, 5000-1 Toyohira, Chino Nagano 391-0292 (Japan); Ohshiro, Yukimitsu; Yamaka, Shouichi; Watanabe, Shin-ichi; Yamaguchi, Hidetoshi; Shimoura, Susumu [Center for Nuclear Study, University of Tokyo, 2-1 Hirosawa, Riken Campus, Wako Saitama 351-0198 (Japan)] [Center for Nuclear Study, University of Tokyo, 2-1 Hirosawa, Riken Campus, Wako Saitama 351-0198 (Japan); Oyaizu, Michihiro; Kase, Masayuki [RIKEN Nishina Center for Accelerator-Based Science, Wako Saitama 351-0198 (Japan)] [RIKEN Nishina Center for Accelerator-Based Science, Wako Saitama 351-0198 (Japan); Kubono, Shigeru [Center for Nuclear Study, University of Tokyo, 2-1 Hirosawa, Riken Campus, Wako Saitama 351-0198 (Japan) [Center for Nuclear Study, University of Tokyo, 2-1 Hirosawa, Riken Campus, Wako Saitama 351-0198 (Japan); RIKEN Nishina Center for Accelerator-Based Science, Wako Saitama 351-0198 (Japan); Institute of Modern Physics, Chinese Academy of Sciences, Nanchang Road 509, Lanzhou 730000 (China); Hattori, Toshiyuki [Heavy Ion Cancer Therapy Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage Chiba 263-855 (Japan)] [Heavy Ion Cancer Therapy Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage Chiba 263-855 (Japan)

2013-07-15

389

Electromagnetic ion cyclotron waves observed in the plasma depletion layer  

NASA Technical Reports Server (NTRS)

Observations from AMPTE/CCE in the earth's magnetosheath on October 5, 1984 are presented to illustrate 0.1 - 4.0 Hz magnetic field pulsations in the subsolar plasma depletion layer (PDL) for northward sheath field during a magnetospheric compression. The PDL is unambiguously identified by comparing CCE data with data from IRM in the upstream solar wind. Pulsations in the PDL are dominated by transverse waves with F/F(H+) 1.0 or less and a slot in spectral power at F/F(H+) = 0.5. The upper branch is left hand polarized while the lower branch is linearly polarized. In the sheath the proton temperature anisotropy is about 0.6 but it is about 1.7 in the PDL during wave occurrence. The properties and correlation of waves with increased anisotropy indicate that they are electromagnetic ion cyclotron waves.

Anderson, B. J.; Fuselier, S. A.; Murr, D.

1991-01-01

390

Electromagnetic ion cyclotron waves in the plasma depletion layer  

NASA Technical Reports Server (NTRS)

Results of a study of the theoretical properties of electromagnetic ion cyclotron (EMIC) waves which occur in the plasma depletion layer are presented. The analysis assumes a homogeneous plasma with the characteristics which were measured by the AMPTE/CCE satellite at 1450-1501 UT on October 5, 1984. Waves were observed in the Pc 1 frequency range below the hydrogen gyrofrequency, and these waves are identified as EMIC waves. The higher-frequency instability is driven by the temperature anisotropy of the H(+) ions, while the lower-frequency instability is driven by the temperature anisotropy of the He(2+) ions. It is argued that the higher-frequency waves will have k roughly parallel to B(0) and will be left-hand polarized, while the lower frequency wave band will have k oblique to B(0) and will be linearly polarized, in agreement with observations.

Denton, Richard E.; Hudson, Mary K.; Fuselier, Stephen A.; Anderson, Brian J.

1993-01-01

391

Searching for Proton Cyclotron Features in Two Magnetar Candidates  

NASA Astrophysics Data System (ADS)

Soft gamma-ray repeaters, SGRs, and anomalous X-ray pulsars, AXPs, might contain ``magnetars'', young neutron stars endowed with ultra-high magnetic fields, which shine as X-ray sources by releasing magnetic energy. Models involving accretion are not ruled out yet. For the magnetic fields of magnetars, proton cyclotron features, PCFs, are expected to lie in the X-ray band (E(PCFs) = 0.63 B/(10^{14} G) keV). Model atmosphere calculations predict that PCFs are conspicuous and relatively broad. We propose here to search for PCFs in the X-ray spectrum of a SGR (SGR1900+14) and an AXP (1E1048-59), by exploiting the unique characteristics of the Chandra HETGS and METGS. These observation might provide decisive evidence in favor of the existence of magnetars.

Stella, Luigi

2001-09-01

392

Electron cyclotron beam measurement system in the Large Helical Devicea)  

NASA Astrophysics Data System (ADS)

In order to evaluate the electron cyclotron (EC) heating power inside the Large Helical Device vacuum vessel and to investigate the physics of the interaction between the EC beam and the plasma, a direct measurement system for the EC beam transmitted through the plasma column was developed. The system consists of an EC beam target plate, which is made of isotropic graphite and faces against the EC beam through the plasma, and an IR camera for measuring the target plate temperature increase by the transmitted EC beam. This system is applicable to the high magnetic field (up to 2.75 T) and plasma density (up to 0.8 × 1019 m-3). This system successfully evaluated the transmitted EC beam profile and the refraction.

Kamio, S.; Takahashi, H.; Kubo, S.; Shimozuma, T.; Yoshimura, Y.; Igami, H.; Ito, S.; Kobayashi, S.; Mizuno, Y.; Okada, K.; Osakabe, M.; Mutoh, T.

2014-11-01

393

Ring Current Ion Coupling with Electromagnetic Ion Cyclotron Waves  

NASA Technical Reports Server (NTRS)

A new ring current global model has been developed for the first time that couples the system of two kinetic equations: one equation describes the ring current (RC) ion dynamic, and another equation describes wave evolution of electromagnetic ion cyclotron waves (EMIC). The coupled model is able to simulate, for the first time self-consistently calculated RC ion kinetic and evolution of EMIC waves that propagate along geomagnetic field lines and reflect from the ionosphere. Ionospheric properties affect the reflection index through the integral Pedersen and Hall coductivities. The structure and dynamics of the ring current proton precipitating flux regions, intensities of EMIC, global RC energy balance, and some other parameters will be studied in detail for the selected geomagnetic storms. The space whether aspects of RC modelling and comparison with the data will also be discussed.

Khazanov, George V.

2002-01-01

394

Alternative optical concept for electron cyclotron emission imaginga)  

NASA Astrophysics Data System (ADS)

The implementation of advanced electron cyclotron emission imaging (ECEI) systems on tokamak experiments has revolutionized the diagnosis of magnetohydrodynamic (MHD) activities and improved our understanding of instabilities, which lead to disruptions. It is therefore desirable to have an ECEI system on the ITER tokamak. However, the large size of optical components in presently used ECEI systems have, up to now, precluded the implementation of an ECEI system on ITER. This paper describes a new optical ECEI concept that employs a single spherical mirror as the only optical component and exploits the astigmatism of such a mirror to produce an image with one-dimensional spatial resolution on the detector. Since this alternative approach would only require a thin slit as the viewing port to the plasma, it would make the implementation of an ECEI system on ITER feasible. The results obtained from proof-of-principle experiments with a 125 GHz microwave system are presented.

Liu, J. X.; Milbourne, T.; Bitter, M.; Delgado-Aparicio, L.; Dominguez, A.; Efthimion, P. C.; Hill, K. W.; Kramer, G. J.; Kung, C.; Kubota, S.; Kasparek, W.; Lu, J.; Pablant, N. A.; Park, H.; Tobias, B.

2014-11-01

395

Excitation of Electron Cyclotron Harmonic Waves in Earth's Magnetotail  

NASA Astrophysics Data System (ADS)

This dissertation investigates the generation mechanism, spatial distribution and characteristics of electrostatic electron cyclotron harmonic (ECH) waves under different plasma sheet conditions, and quantifies the role of these waves in producing the diffuse aurora. THEMIS observations from five magnetotail seasons, along with ray-tracing, and electron diffusion codes have been utilized towards that goal. By modeling the wave growth and quasi-linear pitch-angle diffusion of electrons with realistic parameters for the magnetic field, loss-cone distribution and wave intensity (obtained from observations as a function of magnetotail location), we estimate the loss-cone fill ratio and the contribution of auroral energy flux from wave-induced electron precipitation. We conclude that ECH waves are the dominant driver of electron precipitation in the middle to outer magnetotail.

Zhang, Xiaojia

396

Quantum dynamics of a dissipative and confined cyclotron motion  

NASA Astrophysics Data System (ADS)

We study the dissipative dynamics of a charged oscillator in a magnetic field by coupling (a la Caldeira and Leggett) it to a heat bath consisting of non-interacting harmonic oscillators. We derive here the autocorrelation functions of the position and momentum and study its behavior at various limiting situations. The equilibrium (steady state) dispersions of position and momentum are obtained from their respective autocorrelation functions. We analyze the equilibrium position and momentum dispersions at low and high temperatures for both low and high magnetic field strengths. We obtain the classical diffusive behavior (at long times) as well as the equilibrium momentum dispersion of the free quantum charged particle in a magnetic field, in the limit of vanishing oscillator potential ?0. We establish the relations between the reduced partition function and the equilibrium dispersions of the dissipative and confined cyclotron problem.

Kumar, Jishad

2014-01-01

397

KEKCB electron cyclotron resonance charge breeder at TRIAC.  

PubMed

The KEKCB is an electron cyclotron resonance (ECR) ion source for converting singly charged ions to multicharged ones at Tokai Radioactive Ion Accelerator Complex. By using the KEKCB, singly charged gaseous and nongaseous ions were converted to multicharged ones of A/q approximately 7 with efficiencies of 7% and 2%, respectively. The conversion efficiency was found to be independent of the lifetime of the radioactive nuclei having lifetimes of the order of one second. Three collimators located at the entrance and the exit of the KEKCB defined the beam axis and facilitated beam injection. Grinding and washing the surfaces of aluminum electrode and plasma chamber dramatically reduced impurities originating from the ECR plasma of the KEKCB. PMID:18315161

Imai, N; Jeong, S C; Oyaizu, M; Arai, S; Fuchi, Y; Hirayama, Y; Ishiyama, H; Miyatake, H; Tanaka, M H; Okada, M; Watanabe, Y X; Ichikawa, S; Kabumoto, H; Osa, A; Otokawa, Y; Sato, T K

2008-02-01

398

Data processing in Fourier transform ion cyclotron resonance mass spectrometry.  

PubMed

The Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer intricately couples advanced physics, instrumentation, and electronics with chemical and particularly biochemical research. However, general understanding of the data processing methodologies used lags instrumentation, and most data processing algorithms we are familiar with in FT-ICR are not well studied; thus, professional skill and training in FT-ICR operation and data analysis is still the key to achieve high performance in FT-ICR. This review article is focused on FT-ICR data processing, and explains the procedures step-by-step for users with the goal of maximizing spectral features, such as mass accuracy, resolving power, dynamic range, and detection limits. PMID:24403247

Qi, Yulin; O'Connor, Peter B

2014-01-01

399

Modeling multiple-frequency electron cyclotron resonance heatinga)  

NASA Astrophysics Data System (ADS)

Electron cyclotron resonance (ECR) heating influences two of the main parameters (electron temperature and, indirectly, density) that determine the charge state of the ions produced in an ECR ion source (ECRIS). Therefore, various schemes to optimize ECR heating in the ECRIS have been pursued such as multiple-frequency heating, the radio-frequency tuning effect, volume heating, or wide-band heating. We investigate two-frequency ECR heating of electrons in a simple magnetic mirror field by right handed circularly polarized waves with infinite phase velocity. The study shows a heating barrier different from the well-know adiabatic barrier. Study also revealed a mechanism whereby multiple frequencies give improved heating. A preliminary interpretation of the study is presented.

Spencer, J. Andrew; Kim, Charlson; Kim, Jin-Soo; Evstatiev, Evstati G.; Svidzinski, Vladimir; Cluggish, Brian

2014-02-01

400

Modeling multiple-frequency electron cyclotron resonance heating.  

PubMed

Electron cyclotron resonance (ECR) heating influences two of the main parameters (electron temperature and, indirectly, density) that determine the charge state of the ions produced in an ECR ion source (ECRIS). Therefore, various schemes to optimize ECR heating in the ECRIS have been pursued such as multiple-frequency heating, the radio-frequency tuning effect, volume heating, or wide-band heating. We investigate two-frequency ECR heating of electrons in a simple magnetic mirror field by right handed circularly polarized waves with infinite phase velocity. The study shows a heating barrier different from the well-know adiabatic barrier. Study also revealed a mechanism whereby multiple frequencies give improved heating. A preliminary interpretation of the study is presented. PMID:24593493

Spencer, J Andrew; Kim, Charlson; Kim, Jin-Soo; Evstatiev, Evstati G; Svidzinski, Vladimir; Cluggish, Brian

2014-02-01

401

Concept for a fourth generation electron cyclotron resonance ion source  

SciTech Connect

A fourth generation electron cyclotron resonance ion source with an operating frequency between 40 and 56 GHz has the potential to quadruple the heavy-ion beam currents and provide a cost effective upgrade path for heavy ion drivers in use or in the planning stage at radioactive beam facilities. Design studies show it is feasible to produce the required magnetic fields in the plasma chamber, 7 T axially and 4 T in the radial direction with a magnetic structure using commercially available Nb{sub 3}Sn superconducting materials. In this paper we describe the design of such a magnet structure including a 3D analysis of the Lorentz forces generated by the magnetic fields and the necessary clamping structure to stabilize the conductor against these forces.

Lyneis, C.; Ferracin, P.; Caspi, S.; Hodgkinson, A.; Sabbi, G. L. [Lawrence Berkeley National Laboratory, Berkeley, California 94708 (United States)

2012-02-15

402

Ion cyclotron range of frequencies antenna design for R tokamak  

SciTech Connect

The ion cyclotron range of frequencies antenna design for the R tokamak (a proposal by the Institute of Plasma Physics, Nagoya University) is described. The design involves three types of antennas: a standard loop antenna, a panel heater antenna, and a waveguide antenna for ion Bernstein wave heating (IBWH). The standard loop antenna is made of aluminum alloy and has a simple structure because it has to be installed under radioactive conditions by deuterium-tritium neutrons. A new type of antenna called a panel heater antenna has been designed for high-power heating. It has a wide radiation area and is able to select a parallel wave number kappa/sub parallel/. The feasibility of the waveguide antenna is also discussed in association with IBWH. The radiation from the aperture of the double ridge waveguide is estimated in a model experiment, where calculated surface plasma impedance is simulated by a dielectric load.

Kako, E.; Ando, R.; Ichimura, M.; Ogawa, Y.; Amano, T.; Watari, T.

1987-09-01

403

Electron-cyclotron-current-drive efficiency in DEMO plasmas  

NASA Astrophysics Data System (ADS)

The achievable efficiency for external current drive through electron-cyclotron waves in a demonstration tokamak reactor is investigated. Two possible reactor designs, one for steady state and one for pulsed operation, are considered. Beam propagation, absorption and current drive are modelled employing the beam-tracing technique and including momentum conservation in electron-electron collisions. It is found that for midplane injection the achievable current drive efficiency is limited by second-harmonic absorption at levels consistent with previous studies. Higher efficiencies can be achieved by injecting the beams from the top of the machine, exploiting wave absorption by more energetic (less collisional) electrons. Current drive efficiencies competitive with those usually obtained by neutral beam current drive are reported. These optimum efficiencies are found for frequencies around 230 GHz and 290 GHz for the steady-state and the pulsed DEMO, supposed to operate at a magnetic field B = 5.84 T and B = 7.45 T, respectively.

Poli, E.; Tardini, G.; Zohm, H.; Fable, E.; Farina, D.; Figini, L.; Marushchenko, N. B.; Porte, L.

2013-01-01

404

Magnetic-field measurements for the Lewis Research Center cyclotron  

NASA Technical Reports Server (NTRS)

The magnetic field of the Lewis Center cyclotron was mapped by using a Hall-effect magnetic-field transducer. Main-field Fourier coefficients were determined on a polar mesh of 40 radii for each of seven levels of main-field coil current. Incremental fields for eight sets of trim coils and two sets of harmonic coils were also determined at four of these main-field levels. A stored-program, digital computer was used to perform the measurements. The process was entirely automatic; all data-taking and data-reduction activities were specified by the computer programs. A new method for temperature compensation of a Hall element was used. This method required no temperature control of the element. Measurements of the Hall voltage and Hall-element resistance were sufficient to correct for temperature effects.

Fessler, T. E.

1973-01-01

405

Electron-cyclotron-resonance (ECR) plasma thruster research  

NASA Technical Reports Server (NTRS)

An experimental apparatus to scientifically investigate the process of Electron-Cyclotron-Resonance (ECR) plasma acceleration has been tested. The apparatus consists of a vacuum facility, a 20 kW microwave power supply, and an argon ECR plasma thruster. Present instrumentation allows measurement of microwave input power, reflected power, propellant flow rate, and static pressure in the vacuum tank. In initial tests, an argon ECR plasma has been initiated repeatably at power levels ranging from 0.3 to 7.0 kW. The ECR plasma appears to diverge and separate from the applied magnetic field as predicted by theory. These tests suggest that the ECR plasma acceleration concept can be studied scientifically in the new apparatus.

Sercel, Joel C.

1988-01-01

406

Characteristics of microinstabilities in electron cyclotron and ohmic heated discharges  

SciTech Connect

Characteristics of microinstabilities in electron cyclotron (EC) and ohmic heated (OH) discharges in the T10 tokamak have been analyzed by linear electrostatic gyrokinetic simulations with gyro[J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] aiming to find insights into the effect of auxiliary heating on the transport. Trapped electron modes are found to be unstable in both OH and the EC heated scenarios. In the OH case the main drive is from the density gradient and in the EC case from the electron temperature gradient. The growth rates and particle fluxes exhibit qualitatively different scaling with the electron-to-ion temperature ratios in the two cases. This is mainly due to the fact that the dominant drives and the collisionalities are different. The inward flow velocity of impurities and the impurity diffusion coefficient decreases when applying EC heating, which leads to lower impurity peaking, consistently with experimental observations.

Pusztai, I.; Moradi, S.; Fueloep, T. [Department of Applied Physics, Nuclear Engineering, Chalmers University of Technology and Euratom-VR Association, Goeteborg (Sweden); Timchenko, N. [Institute of Tokamak Physics, NRC ''Kurchatov Institute,'' 123182, Kurchatov Sq. 1, Moscow (Russian Federation)

2011-08-15

407

Characteristics of microinstabilities in electron cyclotron and ohmic heated discharges  

NASA Astrophysics Data System (ADS)

Characteristics of microinstabilities in electron cyclotron (EC) and ohmic heated (OH) discharges in the T10 tokamak have been analyzed by linear electrostatic gyrokinetic simulations with gyro [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] aiming to find insights into the effect of auxiliary heating on the transport. Trapped electron modes are found to be unstable in both OH and the EC heated scenarios. In the OH case the main drive is from the density gradient and in the EC case from the electron temperature gradient. The growth rates and particle fluxes exhibit qualitatively different scaling with the electron-to-ion temperature ratios in the two cases. This is mainly due to the fact that the dominant drives and the collisionalities are different. The inward flow velocity of impurities and the impurity diffusion coefficient decreases when applying EC heating, which leads to lower impurity peaking, consistently with experimental observations.

Pusztai, I.; Moradi, S.; Fülöp, T.; Timchenko, N.

2011-08-01

408

The rare isotope beams production at the Texas A and M university Cyclotron Institute  

SciTech Connect

The Cyclotron Institute at Texas A and M initiated an upgrade project for the production of radioactive-ion beams that incorporates a light-ion guide (LIG) and a heavy-ion guide coupled (HIG) with an Electron Cyclotron Resonance Ion Source (ECRIS) constructed for charge-boosting (CB-ECRIS). This scheme is intended to produce radioactive beams suitable for injection into the K500 superconducting cyclotron. The current status of the project and details on the ion sources and devices used in the project is presented.

Tabacaru, G.; May, D. P.; Chubarian, G.; Clark, H.; Kim, G. J.; Tribble, R. E. [Cyclotron Institute, Texas A and M University, College Station, Texas 77843-3366 (United States); Arje, J. [Accelerator Laboratory, University of Jyvaeskylae, Jyvaeskylae (Finland)

2013-04-19

409

Design Features Of K = 100 Cyclotron Magnet For ISOL RIB Production  

SciTech Connect

K = 100 Separated Sector Cyclotron was designed in conceptual for the ISOL driver. It has 4 separated sector magnets. Two SF cyclotrons will be used as the injectors for separated sector cyclotron. RF frequency is 70 MHz, 4th harmonics. We have designed sector magnet without trim and harmonic coils. Minimum radius of the magnet is 55 cm and maximum radius is 1.8 m. Designed magnets were calculated and simulated by OPERA 3D (TOSCA) code. Ion beam dynamics calculations have been done using particle studio code to prove the focusing properties of the designed magnets.

Park, Jin Ah [Lab. of Accelerator and Medical Engineering, School of Information and Communication, Engineering, SungKyunKwan University, 300 Cheoncheon-dong, Suwon Gyeonggido 440-746 (Korea, Republic of); Gad, Kh. M. M. [Department of Energy Science, SungKyunKwan University, 300 Cheoncheon-dong, Suwon Gyeonggi-do 440-330 (Korea, Republic of); Chai, Jong-Seo [Lab. of Accelerator and Medical Engineering, School of Information and Communication, Engineering, SungKyunKwan University, 300 Cheoncheon-dong, Suwon Gyeonggido 440-746 (Korea, Republic of); Department of Energy Science, SungKyunKwan University, 300 Cheoncheon-dong, Suwon Gyeonggi-do 440-330 (Korea, Republic of)

2011-06-01

410

Spiraling ion beam driven electrostatic ion cyclotron wave instabilities in collisionless dusty plasma  

NASA Astrophysics Data System (ADS)

The numerical calculations of the growth rate in long parallel wavelength are made for a spiraling ion beam propagating through a collision less magnetized dusty plasma cylinder that drives electrostatic ion cyclotron waves to instability via cyclotron interaction. It is found that the growth rate of the instability of the electrostatic ion cyclotron waves increase in the long parallel limit with the density ratio of negatively charged dust grains to electrons. The growth rate of the unstable mode has the maximum value for the modes whose Eigen functions peak at the location of the beam and varies as the one-third power of the beam current in both the limits.

Sharma, Shatendra; Sharma, Jyotsna

2014-08-01

411

Production of rare isotope beams at the Texas A&M University Cyclotron Institute.  

PubMed

The Cyclotron Institute at Texas A&M is currently configuring a scheme for the production of radioactive-ion beams that incorporates a light-ion guide and a heavy-ion guide coupled with an electron-cyclotron-resonance ion source constructed for charge-breeding. This scheme is part of an upgrade to the facility and is intended to produce radioactive beams suitable for injection into the K500 superconducting cyclotron. The current status of the project and details on the ion sources used in the project is presented. PMID:22380246

Tabacaru, G; May, D P; Arje, J; Chubarian, G; Clark, H; Kim, G J; Tribble, R E

2012-02-01

412

A room temperature electron cyclotron resonance ion source for the DC-110 cyclotrona)  

NASA Astrophysics Data System (ADS)

The project of the DC-110 cyclotron facility to provide applied research in the nanotechnologies (track pore membranes, surface modification of materials, etc.) has been designed by the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research (Dubna). The facility includes the isochronous cyclotron DC-110 for accelerating the intensive Ar, Kr, Xe ion beams with 2.5 MeV/nucleon fixed energy. The cyclotron is equipped with system of axial injection and ECR ion source DECRIS-5, operating at the frequency of 18 GHz. This article reviews the design and construction of DECRIS-5 ion source along with some initial commissioning results.

Efremov, A.; Bogomolov, S.; Lebedev, A.; Loginov, V.; Yazvitsky, N.

2014-02-01

413

A PIXE mini-beam setup at the bonn cyclotron for archeometric metal analyses  

NASA Astrophysics Data System (ADS)

The exact analysis of the elemental composition at and around a soldering joint of an antique piece of jewelry can elucidate the joining technologies and give hints of the genuineness of the object. As analytical method we use PIXE, which is nondestructive, multielemental and with fundamental parameter calculations gives absolute concentration values. To obtain the necessary spot size of the H 2+ beam at the Bonn cyclotron we use a piezo-controlled diaphragm, whose demagnified image is focussed on the target by two magnetic quadrupole triplets. With an electrostatic deflector the beam spot of 0.1 × 0.3 mm 2 size can be moved 2 mm in each direction on the target. With a laser beam, which simulates the ion beam, an irregularly shaped archeological object can be positioned. The laser is also used to obtain the alignment of the target surface to the ion beam direction and the small beam size makes it easier to find a flat part on the surface of the object; both of these are important preconditions for using the fundamental parameter method. A scan over a joint of modern gold alloys demonstrates the ability to detect soldering joints. The analysis of four pieces of Roman gold jewelry found in the area of Cologne and Bonn shows examples of brazing with a solder as well as diffusion soldering.

Weber, J.; Beier, Th.; Diehl, U.; Lambrecht, D.; Mommsen, H.; Pantenburg, F. J.

1990-04-01

414

Finite beta effects on the drift-cyclotron instability. [pressure ratio in plasma pinch  

NASA Technical Reports Server (NTRS)

The effects of finite plasma beta and strong plasma inhomogeneities on the microinstability resulting from the unstable coupling of ion-cyclotron oscillations and an ion drift wave are examined. A local electromagnetic, kinetic dispersion equation, which takes into account finite orbit modifications of both ions and electrons as well as the effects of strong inhomogeneities on the ions and permits the continuous tracking of the instability from the weak gradient regime to the strong gradient regime, is derived and solved numerically. Finite beta is shown to increase the frequency and reduce the growth rate of the instability, but not completely stabilize it due to electromagnetic effects. When plasma inhomogeneity is sufficiently strong, finite beta reduces the growth rate of the large k sub y band of a given harmonic more than the small k sub y band; however, the most unstable bands remain the same as in the case of zero beta. Implications of these results for the Tandem Mirror Experiment are discussed.

Gladd, N. T.; Huba, J. D.

1979-01-01

415

Medical muddle.  

PubMed

Nanette Gartrell, MD, is a psychiatrist and researcher whose investigations have documented the mental health and psychological well-being of lesbian, gay, bisexual, and transgender (LGBT) people over the past four decades. Nanette is the principal investigator of an ongoing longitudinal study of lesbian families in which the children were conceived by donor insemination. Now in its 27th year, this project has been cited internationally in the debates over equality in marriage, foster care, and adoption. Previously on the faculty at Harvard Medical School and the University of California, San Francisco, Nanette is currently a Visiting Distinguished Scholar at the Williams Institute, UCLA School of Law. In 2013, Nanette received the Association of Women Psychiatrists Presidential Commendation Award for "selfless and enduring vision, leadership, wisdom, and mentorship in the fields of women's mental health, ethics, and gender research." At the age of 63, Nanette experienced a 3 ½ month period of intractable, incapacitating dizziness for which there was never a clear diagnosis. PMID:24400630

Gartrell, Nanette

2014-01-01

416

Medical education: progress and retreat.  

PubMed

In summary, there have been significant educational improvements, particularly during the first two years of medical school. Students today are more accomplished, more diverse, and there is now a focus on the highly relevant basic science of medical practice, including medical ethics and public health. The curriculum has been centralized and coordination between various departments has vastly improved as a result. The number of lectures has been reduced, replaced by more effective small-group, problem-solving seminars. Support services for students have made medical school a much more enjoyable experience. On the other hand, the dramatic shift in the nature of hospitalized patients has adversely affected traditional bedside teaching that was such an important part of clinical education in the past. Extensive diagnostic evaluations now take place in an ambulatory setting. Hospitals and medical schools have not yet found a satisfactory way to integrate trainees into these venues. Finally, there has been a marked decrease in the number of graduates seeking careers in primary care, a phenomenon influenced by huge educational debts, the attraction of being able to master a defined discipline, and the desire to combine a medical life with a reasonable life-style. On balance, although the overall education of our future doctors has definitely been improved in the past fifty years, the erosion in fundamental clinical skills has been a disappointment. PMID:21073012

Gifford, Robert H

2010-10-01

417

Cyclotron-based nuclear science. Progress report, April 1, 1979-March 31, 1980  

SciTech Connect

Research at the cyclotron institute is summarized. These major areas are covered: nuclear structure; nuclear reactions and scattering; polarization studies; interdisciplinary nuclear science; instrumentation and systems development; and publications. (GHT)

Not Available

1980-06-01

418

ELECTRON CYCLOTRON RESONANCE DISCHARGE AS A SOURCE FOR HYDROGEN AND DEUTERIUM IONS PRODUCTION  

E-print Network

beams of negative hydrogen ions is provoked predominantly by international and national programs1 ELECTRON CYCLOTRON RESONANCE DISCHARGE AS A SOURCE FOR HYDROGEN AND DEUTERIUM IONS PRODUCTION electrons and thermoelectrons in negative hydrogen and deuterium ion production. The obtained data

Boyer, Edmond

419

Ultracompact superconducting isochronous cyclotron production of ¹³N for positron emission tomography applications  

E-print Network

Testing was performed on a data acquisition (DAQ) system that was built specifically to characterize a new ultracompact superconducting isochronous cyclotron (USIC) at MIT. A production model of Nitrogen-13 was validated ...

Fitzgerald, Shawn (Shawn Michael)

2013-01-01

420

Shear-flow-driven ion cyclotron and ion sound-drift instabilities of cylindrical inhomogeneous plasma  

SciTech Connect

The effects of the shear flow along the magnetic field on the development of the ion cyclotron, ion sound, and drift instabilities in the radially inhomogeneous cylindrical plasma are studied on the ground of a kinetic approach. It is shown that flow shear not only modifies the frequencies and growth rates of known current driven electrostatic ion cyclotron, ion sound, and drift instabilities, but is the source of the development of specific shear-flow-driven ion cyclotron, ion sound, and drift instabilities. These instabilities are excited at the levels of current along the ambient magnetic field which is below the critical value for the development of the modified by flow shear current driven ion cyclotron, ion sound, and drift instabilities.

Mikhailenko, V. S.; Chibisov, D. V. [Kharkov National University, 61108, Kharkov (Ukraine)

2007-08-15

421

A Tuning Method for Electrically Compensated Ion Cyclotron Resonance Mass Spectrometer Traps  

PubMed Central

We describe a method for tuning electrically compensated ion cyclotron resonance (ICR) traps by tracking the observed cyclotron frequency of an ion cloud at different oscillation mode amplitudes. Although we have used this method to tune the compensation voltages of a custom-built electrically compensated trap, the approach is applicable to other designs that incorporate electrical compensation. To evaluate the effectiveness of tuning, we examined the frequency shift as a function of cyclotron orbit size at different z-mode oscillation amplitudes. The cyclotron frequencies varied by ~ 12 ppm for ions with low z-mode oscillation amplitudes compared to those with high z-mode amplitudes. This frequency difference decreased to ~1 ppm by one iteration of trap tuning. PMID:20060743

Brustkern, Adam M.; Rempel, Don L.; Gross, Michael L.

2010-01-01

422

Multiple Cyclotron Method to Search for CP Violation in the Neutrino Sector  

E-print Network

New low-cost, high-power proton cyclotrons open the opportunity for a novel precision search for CP violation in the light neutrino sector. The accelerators can produce decay-at-rest neutrino beams located at multiple ...

Conrad, Janet

423

A review of ion sources for medical accelerators (invited)  

SciTech Connect

There are two major medical applications of ion accelerators. One is a production of short-lived isotopes for radionuclide imaging with positron emission tomography and single photon emission computer tomography. Generally, a combination of a source for negative ions (usually H- and/or D-) and a cyclotron is used; this system is well established and distributed over the world. Other important medical application is charged-particle radiotherapy, where the accelerated ion beam itself is being used for patient treatment. Two distinctly different methods are being applied: either with protons or with heavy-ions (mostly carbon ions). Proton radiotherapy for deep-seated tumors has become widespread since the 1990s. The energy and intensity are typically over 200 MeV and several 10{sup 10} pps, respectively. Cyclotrons as well as synchrotrons are utilized. The ion source for the cyclotron is generally similar to the type for production of radioisotopes. For a synchrotron, one applies a positive ion source in combination with an injector linac. Carbon ion radiotherapy awakens a worldwide interest. About 6000 cancer patients have already been treated with carbon beams from the Heavy Ion Medical Accelerator in Chiba at the National Institute of Radiological Sciences in Japan. These clinical results have clearly verified the advantages of carbon ions. Heidelberg Ion Therapy Center and Gunma University Heavy Ion Medical Center have been successfully launched. Several new facilities are under commissioning or construction. The beam energy is adjusted to the depth of tumors. It is usually between 140 and 430 MeV/u. Although the beam intensity depends on the irradiation method, it is typically several 10{sup 8} or 10{sup 9} pps. Synchrotrons are only utilized for carbon ion radiotherapy. An ECR ion source supplies multi-charged carbon ions for this requirement. Some other medical applications with ion beams attract developer's interests. For example, the several types of accelerators are under development for the boron neutron capture therapy. This treatment is conventionally demonstrated by a nuclear reactor, but it is strongly expected to replace the reactor by the accelerator. We report status of ion source for medical application and such scope for further developments.

Muramatsu, M.; Kitagawa, A. [National Institute of Radiological Sciences (NIRS), 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan)

2012-02-15

424

A review of ion sources for medical accelerators (invited).  

PubMed

There are two major medical applications of ion accelerators. One is a production of short-lived isotopes for radionuclide imaging with positron emission tomography and single photon emission computer tomography. Generally, a combination of a source for negative ions (usually H- and/or D-) and a cyclotron is used; this system is well established and distributed over the world. Other important medical application is charged-particle radiotherapy, where the accelerated ion beam itself is being used for patient treatment. Two distinctly different methods are being applied: either with protons or with heavy-ions (mostly carbon ions). Proton radiotherapy for deep-seated tumors has become widespread since the 1990s. The energy and intensity are typically over 200 MeV and several 10(10) pps, respectively. Cyclotrons as well as synchrotrons are utilized. The ion source for the cyclotron is generally similar to the type for production of radioisotopes. For a synchrotron, one applies a positive ion source in combination with an injector linac. Carbon ion radiotherapy awakens a worldwide interest. About 6000 cancer patients have already been treated with carbon beams from the Heavy Ion Medical Accelerator in Chiba at the National Institute of Radiological Sciences in Japan. These clinical results have clearly verified the advantages of carbon ions. Heidelberg Ion Therapy Center and Gunma University Heavy Ion Medical Center have been successfully launched. Several new facilities are under commissioning or construction. The beam energy is adjusted to the depth of tumors. It is usually between 140 and 430 MeV?u. Although the beam intensity depends on the irradiation method, it is typically several 10(8) or 10(9) pps. Synchrotrons are only utilized for carbon ion radiotherapy. An ECR ion source supplies multi-charged carbon ions for this requirement. Some other medical applications with ion beams attract developer's interests. For example, the several types of accelerators are under development for the boron neutron capture therapy. This treatment is conventionally demonstrated by a nuclear reactor, but it is strongly expected to replace the reactor by the accelerator. We report status of ion source for medical application and such scope for further developments. PMID:22380341

Muramatsu, M; Kitagawa, A

2012-02-01

425

Mobile medical image retrieval  

NASA Astrophysics Data System (ADS)

Images are an integral part of medical practice for diagnosis, treatment planning and teaching. Image retrieval has gained in importance mainly as a research domain over the past 20 years. Both textual and visual retrieval of images are essential. In the process of mobile devices becoming reliable and having a functionality equaling that of formerly desktop clients, mobile computing has gained ground and many applications have been explored. This creates a new field of mobile information search & access and in this context images can play an important role as they often allow understanding complex scenarios much quicker and easier than free text. Mobile information retrieval in general has skyrocketed over the past year with many new applications and tools being developed and all sorts of interfaces being adapted to mobile clients. This article describes constraints of an information retrieval system including visual and textual information retrieval from the medical literature of BioMedCentral and of the RSNA journals Radiology and Radiographics. Solutions for mobile data access with an example on an iPhone in a web-based environment are presented as iPhones are frequently used and the operating system is bound to become the most frequent smartphone operating system in 2011. A web-based scenario was chosen to allow for a use by other smart phone platforms such as Android as well. Constraints of small screens and navigation with touch screens are taken into account in the development of the application. A hybrid choice had to be taken to allow for taking pictures with the cell phone camera and upload them for visual similarity search as most producers of smart phones block this functionality to web applications. Mobile information access and in particular access to images can be surprisingly efficient and effective on smaller screens. Images can be read on screen much faster and relevance of documents can be identified quickly through the use of images contained in the text. Problems with the many, often incompatible mobile platforms were discovered and are listed in the text. Mobile information access is a quickly growing domain and the constraints of mobile access also need to be taken into account for image retrieval. The demonstrated access to the medical literature is most relevant as the medical literature and their images are clearly the largest knowledge source in the medical field.

Duc, Samuel; Depeursinge, Adrien; Eggel, Ivan; Müller, Henning

2011-03-01

426

BEAM QUALITY STUDIES ON RIKEN RING CYCLOTRON AND RI BEAM FACTORY  

Microsoft Academic Search

The RIKEN RI Beam Factory (RIBF) plans to produce heavy-ion beams of 350 MeV\\/nucleon over the whole range of atomic masses. An accelerator complex used in the RIBF consists of an existing linear accelerator and five cyclotrons. The RIKEN Ring Cyclotron (RRC), the main accelerator in the present facility, will be an injector of the RIBF. Hence, the beam quality

N. Fukunishi; A. Goto; O. Kamigaito; M. Kase; H. Okuno; H. Ryuto; N. Sakamoto

427

Experimental demonstration of an electromagnetically pumped free-electron laser with a cyclotron-harmonic idler  

Microsoft Academic Search

A three-wave, free-electron laser was operated with a powerful 8.4-GHz electromagnetic ''pump'' wave replacing the usual magnetostatic wiggler. The presence of a uniform axial magnetic field Bâ produced cyclotron-harmonic ''idler'' waves. Peaks in the emission spectrum corresponding to cyclotron harmonics were observed covering a frequency range from 16.5 to 130 GHz. The frequency spectrum of this novel free-electron laser mechanism

R. A. Kehs; Y. Carmel; V. L. Granatstein; W. W. Destler

1988-01-01

428

Saturation of cyclotron maser instability driven by an electron loss-cone distribution  

NASA Technical Reports Server (NTRS)

The resonance diffusion of electrons in velocity space caused by the excited EM wave fields is considered to be the dominant saturation process of cyclotron maser instability that is driven by an electron loss-cone distribution. An upper bound of the saturation level is derived analytically. Since the resulting saturation level is low, the resonance diffusion is indeed responsible for the saturation of the cyclotron maser instability.

Kuo, S. P.; Lee, M. C.

1986-01-01

429

High-intensity cyclotrons for radioisotope production and accelerator driven systems  

NASA Astrophysics Data System (ADS)

IBA recently proposed a new method to extract high-intensity positive ion beams from a cyclotron based on the concept of auto-extraction. We review the design of a 14 MeV, multi-milliampere cyclotron using this new technology. IBA is also involved in the design of the accelerator system foreseen to drive the MYRRHA facility, a multipurpose neutron source developed jointly by SCK-CEN and IBA.

Jongen, Y.; Vandeplassche, D.; Kleeven, W.; Beeckman, W.; Zaremba, S.; Lannoye, G.; Stichelbaut, F.

2002-04-01

430

Medical economics of whole-body FDG PET in patients suspected of having non-small cell lung carcinoma—Reassessment based on the revised Japanese national insurance reimbursement system  

Microsoft Academic Search

Focusing on the savings expected from the revised Japanese national insurance reimbursement system in the management of patients\\u000a suspected of having non-small cell lung carcinoma (NSCLC), cost-effectiveness was assessed using decision tree sensitivity\\u000a analysis on the basis of the 2 competing strategies of whole-body FDG PET (WB-PET) and conventional imaging (CI).Methods: A WB-PET strategy that models dependence upon chest FDG

Katsumi Abe; Shigeru Kosuda; Shoichi Kusano

2003-01-01

431

Your Medical Records  

MedlinePLUS

... Own Medical Records? It's a great idea. Many health care experts recommend that patients keep their own medical summaries or Personal Medical Records (PMRs). That way, they can bring them along ...

432

Reading Your Medical Record  

MedlinePLUS

... H. Shmerling, M.D. is associate physician at Beth Israel Deaconess Medical Center and associate professor at Harvard Medical ... a practicing rheumatologist for over 20 years at Beth Israel Deaconess Medical Center. He is an active teacher in ...

433

When Medication Is Prescribed  

MedlinePLUS

... page please turn Javascript on. Feature: Depression When Medication Is Prescribed Past Issues / Fall 2009 Table of ... you have about the medicine. —NIMH Types of Medications There are several types of medications used to ...

434

Multi-Species Test of Ion Cyclotron Resonance Heating at High Altitudes  

NASA Technical Reports Server (NTRS)

Observations of ion distributions and plasma waves obtained by the Dynamics Explorer 1 satellite in the high-altitude, nightside auroral zone are used to study ion energization for three ion species. A number of theoretical models have been proposed to account for the transverse heating of these ion populations. One of these, the ion cyclotron resonance heating (ICRH) mechanism, explains ion conic formation through ion cyclotron resonance with broadband electromagnetic wave turbulence in the vicinity of the characteristic ion cyclotron frequency. The cyclotron resonant heating of the ions by low- frequency electromagnetic waves is an important energy source for the transport of ions from the ionosphere to the magnetosphere. In this paper we test the applicability of the ICRH mechanism to three simultaneously heated and accelerated ion species by modelling the ion conic formation in terms of a resonant wave-particle interaction in which the ions extract energy from the portion of the broadband electromagnetic wave spectrum which includes the ion cyclotron frequency. Using a Monte Carlo technique we evaluate the ion heating produced by the electromagnetic turbulence at low frequencies and find that the wave amplitudes near the ion cyclotron frequencies are sufficient to explain the observed ion energies.

Persoon, A. M.; Peterson, W. K.; Andre, M.; Chang, T.; Gurnett, D. A.; Retterer, J. M.; Crew, G. B.

1997-01-01

435

Multi-Species Test of Ion Cyclotron Resonance Heating at High Altitudes  

NASA Technical Reports Server (NTRS)

Observations of ion distributions and plasma waves obtained by the Dynamics Explorer 1 satellite in the high-altitude, nightside auroral zone are used to study ion energization for three ion species. A number of theoretical models have been proposed to account for the transverse heating of these ion populations. One of these, the ion cyclotron resonance heating (ICRH) mechanism, explains ion conic formation through ion cyclotron resonance with broadband electromagnetic wave turbulence in the vicinity of the characteristic ion cyclotron frequency. The cyclotron resonant heating of the ions by low-frequency electromagnetic waves is an important energy source for the transport of ions from the ionosphere to the magnetosphere. In this paper we test the applicability of the ICRH mechanism to three simultaneously heated and accelerated ion species by modelling the ion conic formation in terms of a resonant wave-particle interaction in which the ions extract energy from the portion of the broadband electromagnetic wave spectrum which includes the ion cyclotron frequency. Using a Monte Carlo technique we evaluate the ion heating produced by the electromagnetic turbulence at low frequencies and find that the wave amplitudes near the ion cyclotron frequencies are sufficient to explain the observed ion energies.

Persoon, A. M.; Peterson, W. K.; Andre, M.; Chang, T.; Gurnett, D. A.; Retterer, J. M.; Crew, G. B.

1997-01-01

436

An off-center cubic ion trap for Fourier transform ion cyclotron resonance mass spectrometry  

NASA Astrophysics Data System (ADS)

In this paper, we report the rationale and selected experimental results for an off-center cubic ion trap. By forming (or injecting) ions along a line laterally displaced from the axial symmetry axis of the trap, we are able to virtually eliminate space charge effects. Morever, we introduce a new "universal" detection mode in which the frequencies of all three natural motional modes (cyclotron, magnetron, and trapping oscillation) may be determined simultaneously from a single experiment. Due to strong coupling between magnetron and cyclotron modes in the off-center trap, it is possible to detect the "unperturbed" ion cyclotron frequency [nu]c rather than the "reduced" cyclotron frequency [nu]+ leading to trapping voltage-independent mass calibration and improved mass accuracy. Finally, from the excitation voltage amplitude-dependence of the frequency of interconversion between magnetron and cyclotron frequency produced by quadrupolar irradiation at frequency [nu]c we are able to determine the trap geometry factor [alpha] which in turn allows the determination of experimental ion cyclotron orbital radius from conventional dipolar excitation amplitude and duration.

Chen, Ruidan; Marshall, Alan G.

1994-04-01

437

Influence of injection beam emittance on beam transmission efficiency in a cyclotron.  

PubMed

The JAEA AVF cyclotron accelerates various kinds of high-energy ion beams for research in biotechnology and materials science. Beam intensities of an ion species of the order of 10(-9)-10(-6) ampere are often required for various experiments performed sequentially over a day. To provide ion beams with sufficient intensity and stability, an operator has to retune an ion source in a short time. However, the beam intensity downstream of the cyclotron rarely increases in proportion to the intensity at the ion source. To understand the cause of this beam behavior, transmission efficiencies of a (12)C(5+) beam from an electron cyclotron resonance ion source to the cyclotron were measured for various conditions of the ion source. Moreover, a feasible region for acceleration in the emittance of the injection beam was clarified using a transverse-acceptance measuring system. We confirmed that the beam emittance and profile were changed depending on the condition of the ion source and that matching between the beam emittance and the acceptance of the cyclotron was degraded. However, after fine-tuning to improve the matching, beam intensity downstream of the cyclotron increased. PMID:24593459

Kurashima, Satoshi; Kashiwagi, Hirotsugu; Miyawaki, Nobumasa; Yoshida, Ken-Ichi; Okumura, Susumu

2014-02-01

438

Variations of Cyclotron Line Energy with Luminosity in Accreting X-Ray Pulsars  

NASA Astrophysics Data System (ADS)

I develop a new model for changes of cyclotron line energy with luminosity based on changes in polar cap dimensions and the direction of photon propagation as well as a shock height. In X0115+63 and V0332+53, the fundamental cyclotron line energy has been observed to decrease with increasing luminosity. This phenomenon has been interpreted as a change of a shock height with luminosity. However, the rates of the observed changes are quite different, in which the line energy in V0332+53 varies slowly with luminosity compared with that in X0115+63. I demonstrate that a new model successfully reproduces the changes of the fundamental cyclotron line energies with luminosity in both X0115+63 and V0332+53. On the other hand, the cyclotron line energies in Her X-1, GX301-2, and GX304-1 were reported to increase with increasing luminosity. I discuss the positive correlation between the cyclotron line energy and luminosity based on changes in a beam pattern for Her X-1, GX301-2, and GX304-1. In addition, I discuss how a switch of the predominant, observed emission region from pole1 to pole2 influences cyclotron line energy for GX304-1 and A0535+26.

Nishimura, Osamu

2014-01-01

439

ity practitioners, academics, medical professionals, and patient advocacy  

E-print Network

and usage costs. The ben- ing times, faster performance, and lower interface error rates. A second step from medical errors [1]. Many medical errors are never reported or even recognized; only a small number to make more informed personal healthcare decisions. High-quality data about the sources of medical errors

Golbeck, Jennifer

440

Digital halftoning of medical images  

NASA Astrophysics Data System (ADS)

This work considers the use of digital halftones in the display of medical images. One might assume that the use of halftone rendering (as opposed to continuous tone image rendering) will degrade the information in medical images, therefore, it is interesting to study what degree of degradation is unacceptable in medical images. We analyze various halftoning techniques quantitatively by first generating low-contrast detail diagrams (CDD) made to represent computed tomography (CT), magnetic resonance (MR), and ultrasound (US) modality images. These are then halftoned and printed using error diffusion, Bayer's method, blue noise mask, and centered weighted dots. The contrast areas in the diagram are randomly placed on a 5 X 5 grid. A single observer is used to determine the minimum contrast `lesion' that could be observed. The results for minimum detectable contrast depend on resolution (dots per inch), modality, and halftoning technique. It is shown that acceptable halftone rendering, with small degradation, can be achieved under certain conditions.

Silkman, Ronald W.; Parker, Kevin J.

1995-04-01