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A carbon nanotube-based radiation sensor

INTERNATIONAL JOURNAL OF ROBOTICS & AUTOMATION 2007年第1期22卷 49-58页

作者： Ma, J. Yeow, J. T. W. Chow, J. C. L. Barnett, R. B. Univ Waterloo Dept Syst Design Engn Waterloo ON N2L 3G1 Canada Univ Toronto Dept Radiat Oncol Toronto ON M5G 2M9 Canada Univ Toronto Hlth Network Radiat Med Program Toronto ON M5G 2M9 Canada Univ Waterloo Dept Phys Waterloo ON N2L 3G1 Canada Grand River Hosp Grand River Reg Canc Ctr Dept Med Phys Kitchener ON N2G 1G3 Canada

Dosimetric measurements and monitoring play an essential role in radiotherapy. Because of their sensitivity and relatively flat energy response ionization chambers remain the most important dosimeters. However, ionization chambers usually have large physical dimensions and require high bias voltages to achieve acceptable ionization collection efficiency. Such disadvantages limit their applications for in vivo dose measurements. The availability of novel materials such as carbon nanotubes (CNTs) has created the potential to miniaturize traditional ionization chambers and lower the bias voltages. This paper describes a new CNT-based radiation sensor. In the first stage, characteristics of the sensor were examined with two stainless steel electrodes. The sensor displayed excellent linear responses to exposure and showed accurate responses to oblique incident beam measurements. These experimental results showed that the prototype sensor is suitable for studying the ionization collection efficiency of CNTs. In the second stage, square- and irregular-shaped CNTs electrodes were designed. Saturation characteristics of the sensor with the CNTs electrodes were measured. Experimental results and ongoing work are presented and discussed in this paper.

关键词： dosimetry radiation detection radiation sensor carbon nanotubes

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A customized radiation sensor for ionization collection

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IEEE SENSORS JOURNAL 2006年第6期6卷 1523-1530页

作者： Ma, Jiazhi Yeow, John T. W. Chow, James C. L. Barnett, Rob B. Univ Waterloo Dept Syst Design Engn Waterloo ON N2L 3G1 Canada Grand River Hosp Dept Med Phys Grand River Reg Canc Ctr Kitchener ON N2G 1G3 Canada Univ Hlth Network Radiat Med Program Princess Margaret Hosp Toronto ON M5G 2M9 Canada Univ Waterloo Dept Phys Waterloo ON N2L 3G1 Canada

The measurement of absorbed doses is fundamental to radiation biology and oncology. A customized parallel plate radiation sensor was designed and fabricated as a precursor to investigating novel materials,such as carbon nanotubes, as a substitute for conventional metallic conducting plates or active volume medium. This sensor contains two thick and large-area electrodes that provide the sensor with a good signal-to-noise ratio. The 6 MV and 15 MV photon beams produced by a Varian Clinac 21 EX medical linear accelerator were used in the experiments. The linear accelerator was calibrated such that 1 monitor unit (NW) produces 1 cGy of dose in water with depth of 5 cm for a calibration geometry of source-to-axis distance equal to 100 cm and 10 x 10 cm(2) field size at the point of measurement. Ionization measurements were performed by varying the bias voltages, electrode separations, exposures, and angles of the incident beam to characterize the sensor. Signal saturation characteristics of the sensor with different electrode separations and exposures were investigated. This sensor displayed excellent linear response to exposure up to 600 MU. An analytical modeling using the pencil beam model and simulations based on device configuration were given to explain the results. In oblique incident beam experiments, the prototype sensor showed an accurate response compared to simulation results for a small field size of 1 X 1 cm(2). The sensor was tested to be suitable in the study of ionization collection efficiencies for different materials.

关键词： carbon nanotubes (CNTs) dosimetry ionization collection efficiency parallel plate radiation sensor radiation detection

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The jpl roadmap for deep space navigation

The jpl roadmap for deep space navigation

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Spaceflight Mechanics 2006 - AAS/AIAA Space Flight Mechnaics Meeting

作者： Martin-Mur, Tomas J. Abraham, Douglas S. Berry, David Bhaskaran, Shyam Cesarone, Robert J. Wood, Lincoln J. Services Program Office Jet Propulsion Laboratory California Institute of Technology 4800 Oak Grove Drive Pasadena CA 91109 United States Jet Propulsion Laboratory California Institute of Technology Interplanetary Network Directorate Jet Propulsion Laboratory Navigation and Mission Design System Engineering Group California Institute of Technology Guidance Navigation and Control Section Jet Propulsion Laboratory California Institute of Technology

ISBN: (纸本)0877035288

This paper reviews the projected set of deep space missions that will be supported by NASA's Deep Space Mission System in the next twenty-five years, and extracts the driving set of navigation capabilities that these missions will require. There will be many challenges including the support of new mission navigation approaches such as formation flying and rendezvous in deep space, low-energy and low-thrust orbit transfers, precise landing and ascent vehicles, and autonomous navigation. Innovative strategies and approaches will be needed to develop and field advanced navigation capabilities.

关键词： Space research

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Randomized phase III trial of low-dose isotretinoin for prevention of second primary tumors in stage I and II head and neck cancer patients

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JNCI-JOURNAL OF THE NATIONAL CANCER INSTITUTE 2006年第7期98卷 441-450页

作者： Khuri, FR Lee, JJ Lippman, SM Kim, ES Benner, SE Winn, R Pajak, TF Williams, B Shenouda, G Hodson, I Fu, K Shin, DM Vokes, EE Feng, L Goepfert, H Hong, RK Emory Univ Sch Med Winship Canc Inst Atlanta GA 30322 USA Univ Texas MD Anderson Canc Ctr Houston TX 77030 USA Maimonides Hosp New York NY USA Univ Calif San Francisco San Francisco CA 94143 USA Hamilton Reg Canc Ctr Hamilton ON L8V 1C3 Canada SW Oncol Grp San Antonio TX USA Radiat Therapy Oncol Grp Philadelphia PA USA Prot Design Labs Fremont CA USA Univ Chicago Chicago IL 60637 USA Natl Qual Forum Washington DC USA McGill Univ Montreal PQ Canada Canc & Leukemia Grp B Chicago IL USA Community Clin Oncol Program Washington DC USA Texas Community Oncol Network Houston TX USA

Background: Isotretinoin (13-cis-retinoic acid) is a synthetic vitamin A derivative, or retinoid, widely used in the treatment of cystic acne. Preclinical and clinical studies of high-dose isotretinoin in patients with head and neck squamous cell cancer (HNSCC) have produced encouraging results. We conducted a phase III randomized trial of low-dose isotretinoin versus placebo in early-stage HNSCC patients to assess its effect on second primary tumor incidence and survival. Methods: We randomly assigned 1190 patients who had been treated for stage I or II HNSCC to receive either low-dose isotretinoin (30 mg/day) or placebo for 3 years. The patients were monitored for up to 4 more years. Survival was analyzed by the Kaplan-Meier method, and Cox proportional hazards models were used for multivariable survival analysis. All statistical tests were two-sided. Results: Isotretinoin did not statistically significantly reduce the rate of second primary tumors (hazard ratio [HR] = 1.06, 95% confidence interval [CI] = 0.83 to 1.35) or increase survival (HR = 1.039 95% CI = 0.81 to 1.32) compared with placebo in patients with early-stage HNSCC. Current smokers had a higher rate of second primary tumors than that of never (HR = 1.64,95% CI = 1.08 to 2.50) or former (HR = 1.329 95% CI = 1.01 to 1.71) smokers. The hazard ratio of death from any cause for current smokers versus never smokers was 2.51 (95% CI = 1.54 to 4.10) and for current smokers versus former smokers was 1.60 (95% CI = 1.23 to 2.07). Major sites of second primary tumors (n = 261) included lung (31%). oral cavity (17%), larynx (8%), and pharynx (5%). Conclusions: Low-dose isotretinoin was not effective in reducing the rate of second primary tumors or death or smoking-related disease. Smoking statistically significantly increased the rate of second primary tumors and death. Ongoing trials are testing higher doses of isotretinoin as part of combination bioadjuvant therapeutic methods for patients with locally advanc

关键词： Anticarcinogenic Agents Carcinoma Squamous Cell Head and Neck Neoplasms 抗致癌药癌鳞状细胞头颈部肿瘤异维A酸肿瘤继发原发性吸烟 Head and Neck Neoplasms Clinical Trials, Phase III as Topic Squamous Epithelial Cells Current smoker Squamous cell carcinoma of the head and neck Anticarcinogenic Agents hazard ratio Placebos Neoplasm Staging Primary Neoplasm Carcinoma

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The Social Affordances of the Internet for networked Individualism

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Journal of Computer-Mediated Communication 2006年第3期8卷

作者： Barry Wellman Anabel Quan-Haase Jeffrey Boase Wenhong Chen Keith Hampton Isabel Díaz Kakuko Miyata In 1965 moved from his Bronx High School of Science slide rule to IBM cards and an 029 keypunch in the bowels of Harvard University. Since then he's been primarily interested in the interplay between large-scale social processes and how people use technology to be connected at work and in the community. His NetLab research network is trying to get a handle on how the Internet fits into everyday life. Wellman founded the International Network for Social Network Analysis in 1976. He is a recent Chair of the Community section of the American Sociological Association has been nominated for the Chair of the Communication and Information Technology section of the ASA the Virtual Community focus area leader for SIGGROUP/ACM and a Executive Cmmittee member of the Association for Internet Researchers. Wellman's (co)edited books are: Social Structures: A Network Approach (2d ed CSPI 2003) Networks in the Global Village (Westview Press 1999) and The Internet in Everyday Life (Blackwell Publishers 2002). Address:Centre for Urban & Community Studies University of Toronto 455 Spadina Avenue Toronto Canada M5S 2G8. Fax: +1-416-978-7162 Address:Centre for Urban & Community Studies University of Toronto 455 Spadina Avenue Toronto M5S 2G8 Canada. Address:Massachusetts Institute of Technology 77 Mass. Ave. Room 9-522 Cambridge MA 02139. Address:IN3 Av. Tibidabo 47 08035 Barcelona Spain. Phone: +*** Fax: +***. Address:Department of Sociology Meiji Gakuin University 1-2-37 Shirokanedai Minato-ku Tokyo 108-8636 JAPAN. Phone: +81-3-5421-5565 Fax: +81-3-5421-5697. Doctoral student at the Faculty of Information Studies University of Toronto. She has been a Fellow of the Knowledge Media Design Institute and the McLuhan Program in Culture and Technology. Her articles address the nature of Internet-related social change for social integration and information flow. Her articles have examined the implications of these changes for communities and her thesis focuses on organizations. University of Toronto doctoral

We review the evidence from a number of surveys in which our NetLab has been involved about the extent to which the Internet is transforming or enhancing community. The studies show that the Internet is used for connectivity locally as well as globally, although the nature of its use varies in different countries. Internet use is adding on to other forms of communication, rather than replacing them. Internet use is reinforcing the pre-existing turn to societies in the developed world that are organized around networked individualism rather than group or local solidarities. The result has important implications for civic involvement.

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Long-term pulmonary function abnormalities and survival after allogeneic marrow transplantation

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BONE MARROW TRANSPLANTATION 2004年第5期33卷 509-517页

作者： Marras, TK Chan, CK Lipton, JH Messner, HA Szalai, JP Laupacis, A Univ Hlth Network Dept Med Joint Div Respirol Toronto ON Canada Univ Toronto Mt Sinai Hosp Toronto ON M5G 1X5 Canada Univ Toronto Princess Margaret Hosp Dept Med Allogen Bone Marrow Transplant Program Toronto ON Canada Univ Toronto Sunnybrook Hlth Sci Ctr Dept Res Design & Biostat Toronto ON Canada Univ Toronto Womens Coll Hlth Sci Ctr Dept Res Design & Biostat Toronto ON Canada Inst Clin Evaluat Sci Toronto ON Canada Univ Toronto Dept Med Toronto ON Canada

We studied long-term pulmonary function testing (PFT) in a retrospective cohort of 6-month survivors of allogeneic marrow transplant (BMT) between 1980 and 1997. Of 593 patients, 73, 71 and 65% had adequate data to assess for obstruction, restriction and diffusion impairments respectively. Over 5 years, mean declines in 1-s forced expiratory volume/forced vital capacity (FEV1/FVC), total lung capacity (TLC) and diffusion were 4, 7 and 17%, respectively. TLC and diffusion tended to subsequently increase. In all, 6, 12 and 35% of patients met criteria for obstruction, restriction and impaired diffusion, respectively. Obstruction was less common in recent transplants (5 vs 15%, P = 0.004), while restriction and diffusion impairment rates remained stable. There was significantly greater mortality with obstruction (HR 2.0 (1.04-3.95)), and a nonstatistically significant higher mortality rate with restriction (HR 1.6(0.95-2.75)), but not with impaired diffusion (HR = 0.99 (0.65-1.50)). cGVHD (OR 16.7 (2.2-129.8)) and busulfan (OR 2.9 (1.01-8.24)) were associated with obstruction. Marrow from nonsibling or mismatched donors (OR 4.9 (2.2-10.7)) was associated with restriction. In summary, after BMT, decreased diffusion capacity is common and benign;obstruction has decreased in frequency, is rare without cGVHD, and is associated with mortality;nonsibling and mismatched donor are risk factors for restriction.

关键词： bronchiolitis obliterans GVHD lung Respiratory function tests

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Pulmonary function abnormalities after allogeneic marrow transplantation: a systematic review and assessment of an existing predictive instrument

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BONE MARROW TRANSPLANTATION 2002年第9期30卷 599-607页

作者： Marras, TK Szalai, JP Chan, CK Lipton, JH Messner, HA Laupacis, A Univ Toronto Hlth Network Joint Div Resp Toronto ON Canada Univ Toronto Mt Sinai Hosp Dept Med Toronto ON M5G 1X5 Canada Univ Toronto Sunnybrook & Womens Coll Hlth Sci Ctr Dept Res Design & Biostat Toronto ON Canada Univ Toronto Princess Margaret Hosp Dept Med Bone Marrow Transplant Program Toronto ON Canada Univ Toronto Dept Med Toronto ON Canada Inst Clin Evaluat Sci Toronto ON Canada

Pulmonary function testing (PFT) is used to characterize non-infectious pulmonary complications after allogeneic BMT. Identifying high-risk patients could facilitate preventive or early therapeutic measures. The objectives of the study were first, to review available data on PFT changes after BMT and second, to validate a previously published predictive index for PFT obstruction in patients transplanted at one center. For the systematic review, frequency, severity and time course of PFT changes after BMT and for the validation study, retrospective cohort comparing predicted with observed PFT, and calculation of indices of predictive accuracy were summarized. The validation study involved 434 patients from Princess Margaret Hospital, Toronto, Canada, who received their first BMT between 1980 and 1997, survived for at least 6 months and had adequate PFT follow-up. The systematic review included 20 studies. After BMT, decreased diffusion and total lung capacity were common and partially reversible. Obstruction was less common. The validation study of a previously published index, performed in 434 patients, found a sensitivity and specificity of 48% and 68% for identifying patients who develop obstruction. We concluded that PFT changes after BMT are common. A published predictive index is not sufficiently accurate to identify high-risk patients for potential preventive or early therapeutic strategies.

关键词： bone marrow transplantation bronchiolitis obliterans predictive value of tests reproducibility of results respiratory function tests validation study

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Applying fuzzy functions and sequential coordination to optimization of machinery arrangement and pipe routing

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NAVAL ENGINEERS JOURNAL 1998年第6期110卷 43-54页

作者： Wu, BC Young, GS Schmidt, W Choppella, K Dr. Bi-Chu Wu:received a PhD in Mechanical Engineering from the University of Maryland College Park in 1991. She has worked on projects involving naval architecture design optimization solid mechanics and database development. Presently a senwr engineer with Angle Incorporated Dr Wu's research interests are in design optimization and fuzzy logic applications. Dr. Gin-Shu Young: a senior engineer with Angle Incorporated holds a PhD in Mechanical Engineering from the University of Maryland College Park. As a guest researcher with National Institute of Standards and Technologies from 1990 to 1993 he worked on vision-based navigation for autonomous vehicles. His experience also includes applications of optimization fuzzy logic neural network and genetic algorithm methods to engineering system design Mr. William Schmidt:co-founded Angle Incorporated in 1990 and has served as Vice PresidentlChiefScientist during this tame. He holds a B.Sc. in Applied Science from the Naval Acadt?my and an M.Sc. in Physics from the Naval Post Graduate School. He has cner 20 years experience in technical leadership material and personnel management. He has led the application of computer aided design (CAD) and Product Model Information Exchange to the shipbuilding industry. His experience also includes leading the amlication of model based operational analysis to support the Live Fire Test Program for DDG 51 Class Destroyers. Mr. Krishna M. Choppella:is a Sofware Engineer at Eidea Laboratories Incotporated where he works on componentbased distributed enterpvise frameworks. He has been involved in creating data analysis tools for the US Nay by integrating CAD modeis databases and graphical front ends. His work in the Masters degree program in Mechanical Engineering at the University of Texas at Austin was in di0ddase.r spectroscopy of combustion products in porous-matri burners. He received his Bachelors degree in Electrical Engineering in India. He was a Research Associate at the Centre for Laser Technology and Project Engi

Ship design is often multidisciplinary involving several design elements with various types of objectives and constraints (O/C) some easily described as mathematical formulas, others better modeled as descriptive assertions. This paper describes a method based on fuzzy functions and an integrated performance index to model O/C using descriptive assertions to be used with mathematical formulas in optimization. Another issue addressed in this paper concerns the coordination of design elements when sequentially coupled, that is, when one leads the other and the performance of the follower depends greatly on the design of the leader. Based on neuro-fuzzy techniques, the method described here coordinates and optimizes sequentially coupled elements. The two methods are applied to machinery arrangement (MA) and pipe routing (PR). Preliminary models for optimization of MA and PR are described considering convenience, producibility: engine room size, interference and location as factors in the O/C set. Some test results from MA/PR applications are presented and discussed. The methods are generic and can be extended to other elements in ship design. They are mutually independent and may be used separately Two advantages of their use are an improvement in overall performance and a reduction in the need for redesign of elements.

关键词： Optimization

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A VLSI Architecture for Separable 2-D Discrete Wavelet Transform

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Journal of VLSI Signal Processing Systems for Signal, Image, and Video Technology 1998年第2期18卷 125-140页

作者： Limqueco, Jimmy C. Bayoumi, Magdy A. Center for Advanced Computer Studies University of Southwestern Louisiana Lafayette LA 70504 United States University of Southwestern Louisiana United States De La Salle University Philippines Department of Computer Engineering Center for Advanced Computer Studies University of Southwestern Louisiana United States Cairo University Egypt Washington University St. Louis MO United States University of Windsor Canada VLSI Syst. and Applic. Tech. Comm. Neural Network TC Multimedia Technical Committee Technical Program Committee ISCAS MWSCAS Steering Committee ASSP Tech. Comm. on VLSI Processing CS Tech. Committee on VLSI Design Tech. Comm. IEEE VLSI Sign. Proc. W. IEEE Computer Society

In this paper, an efficient semi-systolic array architecture for separable 2-D Discrete Wavelet Transform (DWT) is introduced. The semi-systolic array is applicable to any convolution that requires an arbitrary subsampling function. The semi-systolic array presents a better implementation of the convolution function of DWT. This kind of implementation offers a higher efficiency compared to regular systolic implementation when applied for 2-D DWT. The architecture has an efficiency of at least 91% which increases proportional to the number of octaves with no change in the architecture design except for minor modifications to the control logic and memory size. The propose architecture is scalable for different size of filter and different number of octave. The communication routing is minimum since data transfers are limited to immediate neighboring processors. The components of the architecture are fairly regular and consist of minimum number of computational units which makes it a good candidate for VLSI implementation.

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A DISTRIBUTED MEDIA ACCESS PROTOCOL FOR PACKET RADIO networkS AND PERFORMANCE ANALYSIS .2. network SET-UP TIME AND DATA RATE

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INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS 1995年第1期8卷 49-63页

作者： POND, LC LI, VOK Communication Sciences Electrical Engineering Systems University of Southern California Los Angeles CA 90089-2565 U.S.A. Lawrence C. Pond received the M.Sc. and Ph.D. degrees in electrical engineering from the University of Southern California in 1983 and 1990 respectively. Dr. Pond is currently a scientist at Hughes Space and Communications Company having joined in 1980. He has worked in the fields of communication system design mobile communication network and spacecraft payload design. He is currently working on the development of satellite-based ATM transport and switching architectures for BISDN and Defense Information System Network amlications. Dr. Pond is a member of IEEE. Victor O. K. Li was born in Hong Kong in 1954. He received his SB SM and Sc.D. degrees in Electrical Engineering and Computer Science from the Massachusetts Institute of Technology Cambridge Massachusetts in 1977 1979 and 1981 respectively. Since February 1981 he has been with the University of Southern California (USC) LOS Angeles California where he is Professor of Electrical Engineering and Director of the USC Communication Sciences Institute. He has published 150 technical papers and has lectured and consulted extensively around the world. His research interests include high-speed communication networks personal communication networks intelligent networks distributed databases queueing theory graph theory and applied probability. Dr. Li is very active in the Institute of Electrical and Electronic Engineers (IEEE) having been a member of the Computer Communications Technical Committee since 1983 and having served as Chairman from 1987–1989. He served as Chairman of the Los Angeles Chapter of the IEEE Information Theory Group from 1983–1985. He is the Steering Committee Chair of the International Conference on Computer Communications and Networks (IC3 N) General Chair of the 1st Annual IC3N held in San Diego California in June 1992 General Chair and Technical Program Chair of the 4th IEEE Workshop on Comp

In this, the second part of a two-part paper, the required time for establishing a mobile packet radio network using the virtual circuit and time division multiple access protocol developed in Part 1 is analysed. Tools are developed to determine the virtual circuit and network set-up times in terms of the channel bandwidth allocated to establish and maintain the network. The tools are then extended to include the effects of user mobility. Then these results are combined with the network capacity results of Part 1 to analyse the trade-off between the data rate and set-up time of the network. Next a hierarchical architecture is proposed and the network data rate versus set-up time trade-off of this architecture is analysed using these tools. This architecture is shown to both provide a higher data rate and establish faster than flat networks of the same number of nodes.

关键词： PACKET RADIO network EPLRS DISTRIBUTED network TDMA VIRTUAL CIRCUITS MULTIHOP network BOUNDED DELAY MOBILITY network SET-UP TIME HIERARCHICAL network network DATA RATE

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