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Sample records for extremity tld system

  1. Microprocessor controlled portable TLD system

    NASA Technical Reports Server (NTRS)

    Apathy, I.; Deme, S.; Feher, I.

    1996-01-01

    An up-to-date microprocessor controlled thermoluminescence dosemeter (TLD) system for environmental and space dose measurements has been developed. The earlier version of the portable TLD system, Pille, was successfully used on Soviet orbital stations as well as on the US Space Shuttle, and for environmental monitoring. The new portable TLD system, Pille'95, consists of a reader and TL bulb dosemeters, and each dosemeter is provided with an EEPROM chip for automatic identification. The glow curve data are digitised and analysed by the program of the reader. The measured data and the identification number appear on the LED display of the reader. Up to several thousand measured data together with the glow curves can be stored on a removable flash memory card. The whole system is supplied either from built-in rechargeable batteries or from the mains of the space station.

  2. Microprocessor controlled portable TLD system.

    PubMed

    Apathy, I; Deme, S; Feher, I

    1996-01-01

    An up-to-date microprocessor controlled thermoluminescence dosemeter (TLD) system for environmental and space dose measurements has been developed. The earlier version of the portable TLD system, Pille, was successfully used on Soviet orbital stations as well as on the US Space Shuttle, and for environmental monitoring. The new portable TLD system, Pille'95, consists of a reader and TL bulb dosemeters, and each dosemeter is provided with an EEPROM chip for automatic identification. The glow curve data are digitised and analysed by the program of the reader. The measured data and the identification number appear on the LED display of the reader. Up to several thousand measured data together with the glow curves can be stored on a removable flash memory card. The whole system is supplied either from built-in rechargeable batteries or from the mains of the space station. PMID:11540052

  3. Implementing a new TLD system

    SciTech Connect

    Rhea, T.A.

    1988-01-01

    Martin Marietta Energy Systems will soon be issuing new personnel dosimeters at four of their five Department of Energy (DOE) facilities, The Piketon, Ohio uranium enrichment facility is not included in this dosimetry upgrade program. This talk will focus on the ORNL perspective of this program, especially the new beta-gamma dosimeter. Neutron dosimetry will be discussed briefly. The objective of this upgrade is to put in place a state-of-the-art personnel dosimetry system and to meet the recent DOE Laboratory Accreditation Program performance criteria. Processing such a large number of dosimeters will require stringent quality controls. Approximately 18,000 beta-gamma dosimeters are scheduled for issue in January 1989. 15 figs.

  4. Positional glow curve simulation for thermoluminescent detector (TLD) system design

    NASA Astrophysics Data System (ADS)

    Branch, C. J.; Kearfott, K. J.

    1999-02-01

    Multi- and thin element dosimeters, variable heating rate schemes, and glow-curve analysis have been employed to improve environmental and personnel dosimetry using thermoluminescent detectors (TLDs). Detailed analysis of the effects of errors and optimization of techniques would be highly desirable. However, an understanding of the relationship between TL light production, light attenuation, and precise heating schemes is made difficult because of experimental challenges involved in measuring positional TL light production and temperature variations as a function of time. This work reports the development of a general-purpose computer code, thermoluminescent detector simulator, TLD-SIM, to simulate the heating of any TLD type using a variety of conventional and experimental heating methods including pulsed focused or unfocused lasers with Gaussian or uniform cross sections, planchet, hot gas, hot finger, optical, infrared, or electrical heating. TLD-SIM has been used to study the impact on the TL light production of varying the input parameters which include: detector composition, heat capacity, heat conductivity, physical size, and density; trapped electron density, the frequency factor of oscillation of electrons in the traps, and trap-conduction band potential energy difference; heating scheme source terms and heat transfer boundary conditions; and TL light scatter and attenuation coefficients. Temperature profiles and glow curves as a function of position time, as well as the corresponding temporally and/or spatially integrated glow values, may be plotted while varying any of the input parameters. Examples illustrating TLD system functions, including glow curve variability, will be presented. The flexible capabilities of TLD-SIM promises to enable improved TLD system design.

  5. Dose measurements in space by the Hungarian Pille TLD system.

    PubMed

    Apathy, I; Deme, S; Feher, I; Akatov, Y A; Reitz, G; Arkhanguelski, V V

    2002-10-01

    Exposure of crew, equipment, and experiments to the ambient space radiation environment in low Earth orbit poses one of the most significant problems to long-term space habitation. Accurate dose measurement has become increasingly important during the assembly (extravehicular activity (EVA)) and operation of space stations such as on Space Station Mir. Passive integrating detector systems such as thermoluminescent dosemeters (TLDs) are commonly used for dosimetry mapping and personal dosimetry on space vehicles. The well-known advantages of passive detector systems are their independence of power supply, small dimensions, high sensitivity, good stability, wide measuring range, resistance to environmental effects, and relatively low cost. Nevertheless, they have the general disadvantage that for evaluation purposes they need a laboratory or large--in mass and power consumption--terrestrial equipment, and consequently they cannot provide time-resolved dose data during long-term space flights. KFKI Atomic Energy Research Institute (KFKI AEKI) has developed and manufactured a series of thermoluminescent dosemeter systems for measuring cosmic radiation doses in the 10 microGy to 10 Gy range, consisting of a set of bulb dosemeters and a compact, self-contained, TLD reader suitable for on-board evaluation of the dosemeters. By means of such a system, highly accurate measurements were carried out on board the Salyut-6, -7 and Mir Space Stations as well as on the Space Shuttle. A detailed description of the system is given and the comprehensive results of these measurements are summarised. PMID:12440428

  6. The automated/computerized TLD-personnel monitoring system in Austria

    NASA Astrophysics Data System (ADS)

    Duftschmid, K. E.

    1980-09-01

    The paper discusses the layout and operation details of the automated TLD system used in Austria for several years to monitor some 13000 radiation workers per month. Dosimetric properties, handling and computer software are described.

  7. Evaluation of Effective Sources in Uncertainty Measurements of Personal Dosimetry by a Harshaw TLD System

    PubMed Central

    Hosseini Pooya, SM; Orouji, T

    2014-01-01

    Background: The accurate results of the individual doses in personal dosimety which are reported by the service providers in personal dosimetry are very important. There are national / international criteria for acceptable dosimetry system performance. Objective: In this research, the sources of uncertainties are identified, measured and calculated in a personal dosimetry system by TLD. Method: These sources are included; inhomogeneity of TLDs sensitivity, variability of TLD readings due to limited sensitivity and background, energy dependence, directional dependence, non-linearity of the response, fading, dependent on ambient temperature / humidity and calibration errors, which may affect on the dose responses. Some parameters which influence on the above sources of uncertainty are studied for Harshaw TLD-100 cards dosimeters as well as the hot gas Harshaw 6600 TLD reader system. Results: The individual uncertainties of each sources was measured less than 6.7% in 68% confidence level. The total uncertainty was calculated 17.5% with 95% confidence level. Conclusion: The TLD-100 personal dosimeters as well as the Harshaw TLD-100 reader 6600 system show the total uncertainty value which is less than that of admissible value of 42% for personal dosimetry services. PMID:25505769

  8. The study of new calibration features in the Harshaw TLD system.

    PubMed

    Luo, L Z

    2007-01-01

    The Harshaw TLD system has three key calibration procedures: the Reader, the Dosemeter and the Algorithm. These functions must be properly calibrated for the system to achieve the optimum results. For the conventional reader and dosemeter calibration, Harshaw TLD recommends a pre-fade and a post-fade of 24-48 h when calibrating the system for LiF:Mg,Ti type dosemeter. It is also recommended that keeping the fade time consistent is important to maintain the quality of the system performance. In recent years, new calibration features have been introduced into the Harshaw TLD models 6600 and 8800 operating systems. These new features are Auto Calibration, Auto QC and Auto Blank, and they give the user the ability to set up the clear-expose-read process to be performed automatically in a sequence for each dosemeter. This saves processing time and keeps the fade time the same. However, since the fade time is near zero, will it affect the TLD system calibration factors? What should the user expect? This paper presents a study of the effect of Auto Calibration/Auto QC to the TLD operation. PMID:17223631

  9. Implementation of the Panasonic TLD (Thermoluminescent Dosimeter) system for personnel monitoring at the Nevada Test Site

    SciTech Connect

    DeMarre, M.; Teasdale, C.L.; Sygitowicz, L.S.

    1988-01-01

    In January 1987, the dosimetry system at the Nevada Test Site changed from a film badge dosimetry program to the Panasonic Thermoluminescent Dosimeter (TLD) system to monitor external radiation exposure to personnel working at the Nevada Test Site. In order to implement the Panasonic TLD system, a combination dosimeter and security credential badge holder had to be developed, a computer processing system developed, a dose processing algorithm developed and enough Panasonic UD802AS2 TLDs purchased to support a large quarterly exchange. Problems that had to be resolved during the first year of operation were: processing approximately 15,000 dosimeters per quarter; multiple exchange of the same dosimeter in the same quarter due to incoming visitors and vendors; late returns due to the unique user community at the Nevada Test Site; TLD damage experience and unusual TLD anomalies. The experience from the original planning stages for conversion to the TLD system to the reality of the implementation of this system will be discussed.

  10. An on-board TLD system for dose monitoring on the International Space Station.

    PubMed

    Apathy, I; Deme, S; Bodnar, L; Csoke, A; Hejja, I

    1999-01-01

    This institute has developed and manufactured a series of thermoluminescence dosemeter (TLD) systems for spacecraft, consisting of a set of bulb dosemeters and a small, compact, TLD reader suitable for on-board evaluation of the dosemeters. By means of such a system highly accurate measurements were carried out on board the Salyut-6, -7 and Mir Space Stations as well as on the Space Shuttle. A new implementation of the system will be placed on several segments of the ISS as the contribution of Hungary to this intemational enterprise. The well proven CaSO4:Dy dosemeters will be used for routine dosimetry of the astronauts and in biological experiments. The mean LET value will be measured by LiF dosemeters while doses caused by neutrons are planned to be determined by 6LiF/7LiF dosemeter pairs and moderators. A detailed description of the system is given. PMID:11542233

  11. Study of minimum detection limit of TLD personnel monitoring system in India.

    PubMed

    Sneha, C; Pradhan, S M; Adtani, M M

    2010-09-01

    Personnel monitoring of radiation workers in India is carried out using a thermoluminescence dosemeter (TLD) system based on CaSO(4):Dy Teflon TLD disc. The dose due to occupational exposure for a majority of radiation workers is very small and hence is reported as zero. In view of this the detection of low levels of occupational dose over and above a variable background assumes great importance. The present values of reporting levels are based on the standard deviations of annealed dosemeters and therefore are fixed irrespective of period of use and background radiation levels. The validity of these levels is investigated under laboratory conditions. The laboratory values of standard deviations cannot be used as an indication of the imprecision that occurs during service. Therefore, the validity of the reporting levels is also investigated for control dosemeters used in routine service. PMID:20511403

  12. Unfolding neutron spectra obtained from BS-TLD system using genetic algorithm.

    PubMed

    Santos, J A L; Silva, E R; Ferreira, T A E; Vilela, E C

    2012-12-01

    Due to the variability of neutron spectrum within the same environment, it is essential that the spectral distribution as a function of energy should be characterized. The precise information allows radiological quantities establishment related to that spectrum, but it is necessary that a spectrometric system covers a large interval of energy and an unfolding process is appropriate. This paper proposes use of a technique of Artificial Intelligence (AI) called genetic algorithm (GA), which uses bio-inspired mathematical models with the implementation of a specific matrix to unfolding data obtained from a combination of TLDs embedded in a BS system to characterize the neutron spectrum as a function of energy. The results obtained with this method were in accordance with reference spectra, thus enabling this technique to unfold neutron spectra with the BS-TLD system. PMID:22963980

  13. A whole-body dosimetry system for personal monitoring based on hot-pressed thin layer TLD.

    PubMed

    Busch, F; Engelhardt, J; Martini, E; Lesz, J

    2011-03-01

    We are introducing a new high-capacity thermoluminescent dosemeter (TLD) system to measure the whole body values of H(p)(10) and H(p)(0.07) from photons for use in individual monitoring services. Small and light-weight badges allow a convenient application in a wide variety of workplaces with photon radiation from 20 keV to at least 7 MeV. The main advantage of this system will be the large capacity of ∼ 100,000 dosemeters per month at costs equivalent to the current film monitoring. The hot-pressed thin-layer TL detector (LiF:Mg,Ti) is welded onto an aluminium substrate and provided with a data matrix code for automatic processing. The detector holder has been optimised, that no additional filter is necessary. The new designed TLD reader with readout times <10 s will allow a large throughput and a considerable degree of automation. PMID:21227958

  14. Performance testing of the environmental TLD system for the Three Mile Island Nuclear Station.

    PubMed

    Toke, L F; Carson, B H; Baker, G G; McBride, M H; Plato, P A; Miklos, J A

    1984-05-01

    Panasonic UD-801 thermoluminescent dosimeters ( TLDs ) containing two calcium sulfate phosphors were tested under Performance Specification 3.1 established by the American National Standard Institute ( ANSI75 ) and in the U.S. Nuclear Regulatory Commission's Regulatory Guide 4.13 ( NRC77 ). The specific qualifying tests included TLD uniformity, reproducibility, energy dependence and directional dependence. The overall measurement uncertainties and associated confidence levels are within the prescribed guidelines defined in the qualifying requirements for environmental TLDs . PMID:6724910

  15. SU-E-T-594: Out-Of-Field Neutron and Gamma Dose Estimated Using TLD-600/700 Pairs in the Wobbling Proton Therapy System

    SciTech Connect

    Chen, Y; Lin, Y; Tsai, H

    2015-06-15

    Purpose: Secondary fast neutrons and gamma rays are mainly produced due to the interaction of the primary proton beam with the beam delivery nozzle. These secondary radiation dose to patients and radiation workers are unwanted. The purpose of this study is to estimate the neutron and gamma dose equivalent out of the treatment volume during the wobbling proton therapy system. Methods: Two types of thermoluminescent (TL) dosimeters, TLD-600 ({sup 6}LiF: Mg, Ti) and TLD-700 ({sup 7}LiF: Mg, Ti) were used in this study. They were calibrated in the standard neutron and gamma sources at National Standards Laboratory. Annealing procedure is 400°C for 1 hour, 100°C for 2 hours and spontaneously cooling down to the room temperature in a programmable oven. Two-peak method (a kind of glow curve analysis technique) was used to evaluate the TL response corresponding to the neutron and gamma dose. The TLD pairs were placed outside the treatment field at the neutron-gamma mixed field with 190-MeV proton beam produced by the wobbling system through the polyethylene plate phantom. The results of TLD measurement were compared to the Monte Carlo simulation. Results: The initial experiment results of calculated dose equivalents are 0.63, 0.38, 0.21 and 0.13 mSv per Gy outside the field at the distance of 50, 100, 150 and 200 cm. Conclusion: The TLD-600 and TLD-700 pairs are convenient to estimate neutron and gamma dosimetry during proton therapy. However, an accurate and suitable glow curve analysis technique is necessary. During the wobbling system proton therapy, our results showed that the neutron and gamma doses outside the treatment field are noticeable. This study was supported by the grants from the Chang Gung Memorial Hospital (CMRPD1C0682)

  16. Doses due to the South Atlantic Anomaly during the Euromir'95 mission measured by an on-board TLD system.

    PubMed

    Deme, S; Reitz, G; Apathy, I; Hejja, I; Lang, E; Feher, I

    1999-01-01

    During the Euromir'95 mission, a specially designed microprocessor-controlled thermoluminescent detector (TLD) system, called the 'Pille'95', was used by ESA astronaut Thomas Reiter to measure the cosmic radiation dose inside the Mir space station. One of the experiment's objectives was to determine the dose fraction on Mir due to the South Atlantic Anomaly (SAA) on an orbit inclined at 51.6 degrees and at an altitude of about 400 km. Using an hourly measuring period for 170 h in automatic mode, dose components both of galactic (independent of SAA) and SAA origin were determined. It was found that the maximum dose due to crossing the SAA was equal to 55 microGy. Averaging all the measurements it was calculated that the mean dose rate inside the Mir was 12-14 microGy h-1 and that half of this value was caused by the SAA. PMID:11542232

  17. A robotic manipulator for handling TLD badges.

    PubMed

    Levinson, S; Weinstein, M; Abraham, A; German, U; Gorelik, V; Rozenfeld, R; Hillel, S; Rodnay, G

    2008-11-01

    A prototype system for automatic handling of Harshaw/Bicron (now ThermoFisher Scientific) thermoluminescent dosimetry (TLD) badges, which is based on a robotic arm, was designed and built. The robot performs the loading and unloading of the TLD cards in the badges and transports them between the loading/unloading station and magazine stations. For quality assurance, a sticker containing the worker's details printed in barcode format was added to the badge. Automatic on-line identification is performed for checking the correlation between the badge and the TLD card number. PMID:18849713

  18. Extra dose due to extravehicular activity during the NASA4 mission measured by an on-board TLD system

    NASA Technical Reports Server (NTRS)

    Deme, S.; Apathy, I.; Hejja, I.; Lang, E.; Feher, I.

    1999-01-01

    A microprocessor-controlled on-board TLD system, 'Pille'96', was used during the NASA4 (1997) mission to monitor the cosmic radiation dose inside the Mir Space Station and to measure the extra dose to two astronauts in the course of their extravehicular activity (EVA). For the EVA dose measurements, CaSO4:Dy bulb dosemeters were located in specially designed pockets of the ORLAN spacesuits. During an EVA lasting 6 h, the dose ratio inside and outside Mir was measured. During the EVA, Mir crossed the South Atlantic Anomaly (SAA) three times. Taking into account the influence of these three crossings the mean EVA/internal dose rate ratio was 3.2. Internal dose mapping using CaSO4:Dy dosemeters gave mean dose rates ranging from 9.3 to 18.3 microGy h-1 at locations where the shielding effect was not the same. Evaluation results of the high temperature region of LiF dosemeters are given to estimate the mean LET.

  19. Extra dose due to extravehicular activity during the NASA4 mission measured by an on-board TLD system.

    PubMed

    Deme, S; Apathy, I; Hejja, I; Lang, E; Feher, I

    1999-01-01

    A microprocessor-controlled on-board TLD system, 'Pille'96', was used during the NASA4 (1997) mission to monitor the cosmic radiation dose inside the Mir Space Station and to measure the extra dose to two astronauts in the course of their extravehicular activity (EVA). For the EVA dose measurements, CaSO4:Dy bulb dosemeters were located in specially designed pockets of the ORLAN spacesuits. During an EVA lasting 6 h, the dose ratio inside and outside Mir was measured. During the EVA, Mir crossed the South Atlantic Anomaly (SAA) three times. Taking into account the influence of these three crossings the mean EVA/internal dose rate ratio was 3.2. Internal dose mapping using CaSO4:Dy dosemeters gave mean dose rates ranging from 9.3 to 18.3 microGy h-1 at locations where the shielding effect was not the same. Evaluation results of the high temperature region of LiF dosemeters are given to estimate the mean LET. PMID:11542227

  20. Comparative performance testing of Harshaw 8800 and KDT-02M TLD systems.

    PubMed

    Chumak, V; Volosky, V; Chernyshov, G; Dmitrienko, A; Sukhoruchkin, A; Rozumny, V

    2002-01-01

    The Soviet-produced KDT-02M system, which is still widely used for dosimetric monitoring in countries of the former Soviet Union, was compared with the Harshaw 8800 system. The comparison consisted of two stages. In the first stage workplace radiation fields were simulated in the framework of the IAEA intercomparison. In the second stage the two systems were compared when used in parallel by the personnel of Chernobyl Object 'Shelter'. Although in the first stage the Harshaw 8800 demonstrated better performance for various irradiation conditions, an obsolete KDT-02M also proved compliance with the basic requirements to the accuracy of individual dosimetric monitoring. In the second stage, more than 1200 paired measurements were performed, revealing good (r = 0.95) correlation between readouts of both systems. Deviation of the slope of the regression line may be adjusted by proper calibration. Although the KDT-02M system demonstrated adequate results for measurement of deep dose equivalent, its inability to determine shallow dose equivalent calls for its replacement with modem thermoluminesence dosemeters possessing this feature. PMID:12382819

  1. Intensity variation study of the radiation field in a mammographic system using thermoluminescent dosimeters TLD-900 (CaSO4:Dy)

    NASA Astrophysics Data System (ADS)

    Corrêa, E. L.; Silva, J. O.; Vivolo, V.; Potiens, M. P. A.; Daros, K. A. C.; Medeiros, R. B.

    2014-02-01

    This study presents the results of the intensity variation of the radiation field in a mammographic system using the thermoluminescent dosimeter TLD-900 (CaSO4:Dy). These TLDs were calibrated and characterized in an industrial X-ray system used for instruments calibration, in the energy range used in mammography. They were distributed in a matrix of 19 lines and five columns, covering an area of 18 cm×8 cm in the center of the radiation field on the clinical equipment. The results showed a variation of the intensity probably explained by the non-uniformity of the field due to the heel effect.

  2. Route to extreme events in excitable systems

    NASA Astrophysics Data System (ADS)

    Karnatak, Rajat; Ansmann, Gerrit; Feudel, Ulrike; Lehnertz, Klaus

    2014-08-01

    Systems of FitzHugh-Nagumo units with different coupling topologies are capable of self-generating and -terminating strong deviations from their regular dynamics that can be regarded as extreme events due to their rareness and recurrent occurrence. Here we demonstrate the crucial role of an interior crisis in the emergence of extreme events. In parameter space we identify this interior crisis as the organizing center of the dynamics by employing concepts of mixed-mode oscillations and of leaking chaotic systems. We find that extreme events occur in certain regions in parameter space, and we show the robustness of this phenomenon with respect to the system size.

  3. Thermal quenching of thermoluminescence in TLD-200, TLD-300 and TLD-400 after β-irradiation

    NASA Astrophysics Data System (ADS)

    Kafadar, Vural E.

    2011-02-01

    The dosimetric characteristics of many TL materials are influenced by changes in location, size and shape of the glow curves due to changes in the heating rate. In this study, the effect of heating rate on the integrated peak areas of CaF 2:Dy (TLD-200), CaF 2:Tm (TLD-300) and CaF 2:Mn (TLD-400) crystals have been investigated after β-irradiation. It was observed that the peak temperatures of all peaks shifted to the high temperature sides and the integrated peak areas decrease as the heating rate increases due to thermal quenching, whose efficiency increases as temperature increases.

  4. Extreme-UV lithography system

    DOEpatents

    Replogle, William C.; Sweatt, William C.

    2001-01-01

    A photolithography system that employs a condenser that includes a series of aspheric mirrors on one side of a small, incoherent source of radiation producing a series of beams is provided. Each aspheric mirror images the quasi point source into a curved line segment. A relatively small arc of the ring image is needed by the camera; all of the beams are so manipulated that they all fall onto this same arc needed by the camera. Also, all of the beams are aimed through the camera's virtual entrance pupil. The condenser includes a correcting mirror for reshaping a beam segment which improves the overall system efficiency. The condenser efficiently fills the larger radius ringfield created by today's advanced camera designs. The system further includes (i) means for adjusting the intensity profile at the camera's entrance pupil or (ii) means for partially shielding the illumination imaging onto the mask or wafer. The adjusting means can, for example, change at least one of: (i) partial coherence of the photolithography system, (ii) mask image illumination uniformity on the wafer or (iii) centroid position of the illumination flux in the entrance pupil. A particularly preferred adjusting means includes at least one vignetting mask that covers at least a portion of the at least two substantially equal radial segments of the parent aspheric mirror.

  5. Passive TLD based system for characterisation of spectral and angular properties of high dose rate workplace fields.

    PubMed

    Chumak, V; Bakhanova, E; Shylo, S; Volosky, V; Chernyshov, G

    2002-01-01

    In order to address the problem of characterisation of high dose rate workplace fields, unique techniques and devices have been developed and tested. The kit of devices comprises a passive spectrometric system and six-vector collimator with thermoluminiscent detectors (TLDs) inside, allowing determination of the anisotropy of the radiation field, both horizontal and vertical. The passive spectrometric system makes use of simultaneous exposure of several TLDs placed inside spherical attenuators. Deconvolution of gamma spectra is performed by solving a system of simultaneous linear equations. The problem of solving ill-defined systems of simultaneous equations was addressed by a system regularisation method. The energy resolution of the system is not high (seven to ten energy bins can be distinguished), yet is sufficient for practical needs. After several benchmark tests, the discussed experimental set-up was extensively tested in various locations within Object 'Shelter'. Results of both energy spectrum and exposure geometry characterisation demonstrated the feasibility of the proposed approach. PMID:12382818

  6. Extreme low frequency acoustic measurement system

    NASA Technical Reports Server (NTRS)

    Shams, Qamar A. (Inventor); Zuckerwar, Allan J. (Inventor)

    2013-01-01

    The present invention is an extremely low frequency (ELF) microphone and acoustic measurement system capable of infrasound detection in a portable and easily deployable form factor. In one embodiment of the invention, an extremely low frequency electret microphone comprises a membrane, a backplate, and a backchamber. The backchamber is sealed to allow substantially no air exchange between the backchamber and outside the microphone. Compliance of the membrane may be less than ambient air compliance. The backplate may define a plurality of holes and a slot may be defined between an outer diameter of the backplate and an inner wall of the microphone. The locations and sizes of the holes, the size of the slot, and the volume of the backchamber may be selected such that membrane motion is substantially critically damped.

  7. Observations of an extreme planetary system

    NASA Astrophysics Data System (ADS)

    Raetz, Stefanie; Schmidt, Tobias O. B.; Briceno, Cesar; Neuhäuser, Ralph

    2015-12-01

    Almost 500 planet host stars are already known to be surrounded by more than one planet. Most of them (except HR8799) are old and all planets were found with the same or similar detection method.We present an unique planetary system. For the first time, a close in transiting and a wide directly imaged planet are found to orbit a common host star which is a low mass member of a young open cluster. The inner candidate is the first possible young transiting planet orbiting a previously known weak-lined T-Tauri star and was detected in our international monitoring campaign of young stellar clusters. The transit shape is changing between different observations and the transit even disappears and reappears. This unusual transit behaviour can be explained by a precessing planet transiting a gravity-darkened star.The outer candidate was discovered in the course of our direct imaging survey with NACO at ESO/VLT. Both objects are consistent with a <5 Jupiter mass planet. With ~2.4 Myrs it is among the youngest exoplanet systems. Both planets orbit its star in very extreme conditions. The inner planet is very close to its Roche limiting orbital radius while the outer planet is far away from its host star at a distance of ~660 au. The detailed analysis will provide important constraints on planet formation and migration time-scales and their relation to protoplanetary disc lifetimes. Furthermore, this system with two planets on such extreme orbits gives us the opportunity to study the possible outcome of planet-planet scattering theories for the first time by observations.I will report on our monitoring and photometric follow-up observations as well as on the direct detection and the integral field spectroscopy of this extreme planetary system.

  8. Development of an algorithm for evaluating personal doses due to photon fields in terms of operational quantities for TLD badge system in India.

    PubMed

    Pradhan, S M; Sneha, C; Chourasiya, G; Adtani, M M; Tripathi, S M; Singh, S K

    2009-09-01

    In order to evaluate and report the personal doses in terms of personal dose equivalent, the performance of the CaSO(4):Dy based thermoluminescence dosemeter (TLD) badge used for countrywide personnel monitoring in India is investigated using monoenergetic and narrow spectrum radiation qualities equivalent to those given in ISO standards. Algorithms suitable for evaluating H(p)(10) and H(p)(0.07) within +/- 30 % are developed from the responses of dosemeter elements/discs under different filters for normal as well as angular irradiation conditions using these beams. The algorithm is tested for TLD badges irradiated to mixtures of low- and high-energy ((137)Cs) beams in various proportions. The paper concludes with the results of test of algorithm by evaluation of badges used in the IAEA/RCA intercomparison studies and discussion on inherent limitations. PMID:19755432

  9. SU-E-T-87: Comparison Study of Dose Reconstruction From Cylindrical Diode Array Measurements, with TLD Measurements and Treatment Planning System Calculations in Anthropomorphic Head and Neck and Lung Phantoms

    SciTech Connect

    Benhabib, S; Cardan, R; Huang, M; Brezovich, I; Popple, R; Faught, A; Followill, D

    2014-06-01

    Purpose: To assess dose calculated by the 3DVH software (Sun Nuclear Systems, Melbourne, FL) against TLD measurements and treatment planning system calculations in anthropomorphic phantoms. Methods: The IROC Houston (RPC) head and neck (HN) and lung phantoms were scanned and plans were generated using Eclipse (Varian Medical Systems, Milpitas, CA) following IROC Houston procedures. For the H and N phantom, 6 MV VMAT and 9-field dynamic MLC (DMLC) plans were created. For the lung phantom 6 MV VMAT and 15 MV 9-field dynamic MLC (DMLC) plans were created. The plans were delivered to the phantoms and to an ArcCHECK (Sun Nuclear Systems, Melbourne, FL). The head and neck phantom contained 8 TLDs located at PTV1 (4), PTV2 (2), and OAR Cord (2). The lung phantom contained 4 TLDs, 2 in the PTV, 1 in the cord, and 1 in the heart. Daily outputs were recorded before each measurement for correction. 3DVH dose reconstruction software was used to project the calculated dose to patient anatomy. Results: For the HN phantom, the maximum difference between 3DVH and TLDs was -3.4% and between 3DVH and Eclipse was 1.2%. For the lung plan the maximum difference between 3DVH and TLDs was 4.3%, except for the spinal cord for which 3DVH overestimated the TLD dose by 12%. The maximum difference between 3DVH and Eclipse was 0.3%. 3DVH agreed well with Eclipse because the dose reconstruction algorithm uses the diode measurements to perturb the dose calculated by the treatment planning system; therefore, if there is a problem in the modeling or heterogeneity correction, it will be carried through to 3DVH. Conclusion: 3DVH agreed well with Eclipse and TLD measurements. Comparison of 3DVH with film measurements is ongoing. Work supported by PHS grant CA10953 and CA81647 (NCI, DHHS)

  10. A TLD-based ten channel system for the spectrometry of bremsstrahlung generated by laser-matter interaction

    NASA Astrophysics Data System (ADS)

    Horst, Felix; Fehrenbacher, Georg; Radon, Torsten; Kozlova, Ekaterina; Rosmej, Olga; Czarnecki, Damian; Schrenk, Oliver; Breckow, Joachim; Zink, Klemens

    2015-05-01

    This work presents a thermoluminescence dosimetry based method for the measurement of bremsstrahlung spectra in the energy range from 30 keV to 100 MeV, resolved in ten different energy intervals and for the photon ambient dosimetry in ultrashort pulsed radiation fields as e.g. generated during operation of the PHELIX laser at the GSI Helmholtzzentrum für Schwerionenforschung. The method is a routine-oriented development by application of a multi-filter technique. The data analysis takes around 1 h. The spectral information is obtained by the unfolding of the response of ten thermoluminescence dosimeters with absorbers of different materials and thicknesses arranged as a stack each with a different response function to photon radiation. These response functions were simulated by the use of the Monte Carlo code FLUKA. An algorithm was developed to unfold bremsstrahlung spectra from the readings of the ten dosimeters. The method has been validated by measurements at a clinical electron linear accelerator (6 MV and 18 MV bremsstrahlung). First measurements at the PHELIX laser system were carried out in December 2013 and January 2014. Spectra with photon energies up to 10 MeV and mean energies up to 420 keV were observed at laser-intensities around 1019 W /cm2 on a titanium foil target. The measurement results imply that the steel walls of the target chamber might be an additional bright x-ray source.

  11. Instrumentation for automated acquisition and analysis of TLD glow curves

    NASA Astrophysics Data System (ADS)

    Bostock, I. J.; Kennett, T. J.; Harvey, J. W.

    1991-04-01

    Instrumentation for the automated and complete acquisition of thermoluminescent dosimeter (TLD) data from a Panasonic UD-702E TLD reader is reported. The system that has been developed consists of both hardware and software components and is designed to operate with an IBM-type personal computer. Acquisition of glow curve, timing, and heating data has been integrated with elementary numerical analysis to permit real-time validity and diagnostic assessments to be made. This allows the optimization of critical parameters such as duration of the heating cycles and the time window for the integration of the dosimetry peak. The form of the Li 2B 4O 7:Cu TLD glow curve has been studied and a mathematical representation devised to assist in the implementation of automated analysis. Differences in the shape of the curve can be used to identify dosimetry peaks due to artifacts or to identify failing components. Examples of the use of this system for quality assurance in the TLD monitoring program at McMaster University are presented.

  12. TLD linearity vs. beam energy and modality

    SciTech Connect

    Troncalli, Andrew J.; Chapman, Jane

    2002-12-31

    Thermoluminescent dosimetry (TLD) is considered to be a valuable dosimetric tool in determining patient dose. Lithium fluoride doped with magnesium and titanium (TLD-100) is widely used, as it does not display widely divergent energy dependence. For many years, we have known that TLD-100 shows supralinearity to dose. In a radiotherapy clinic, there are multiple energies and modality beams. This work investigates whether individual linearity corrections must be used for each beam or whether a single correction can be applied to all beams. The response of TLD as a function of dose was measured from 25 cGy to 1000 cGy on both electrons and photons from 6 to 18 MeV. This work shows that, within our measurement uncertainty, TLD-100 exhibits supralinearity at all megavoltage energies and modalities.

  13. Measurement of dose given by Co-60 in radiotherapy with TLD-500

    NASA Astrophysics Data System (ADS)

    Tanır, Güneş; Cengiz, Ferhat; Hicabi Bölükdemir, M.

    2012-04-01

    The uses of dosimeters based on optically stimulated luminescence technique have become widespread in clinical applications. In the present study, the dose values given by Cobalt-60 radiotherapy machine were measured with optically stimulated luminescence (OSL) technique using TLD-500 and compared with those of commonly used ionization chamber dosimeter system. The percentage depth dose (DD%) values and graphs were formed. OSL system with TLD-500 can be reliably used as medical and personal dosimeter.

  14. Nonlinear multimodal model for TLD of irregular tank geometry and small fluid depth

    NASA Astrophysics Data System (ADS)

    Love, J. S.; Tait, M. J.

    2013-11-01

    Tuned liquid dampers (TLDs) utilize sloshing fluid to absorb and dissipate structural vibrational energy. TLDs of irregular or complex tank geometry may be required in practice to avoid tank interference with fixed structural or mechanical components. The literature offers few analytical models to predict the response of this type of TLD, particularly when the fluid depth is small. In this paper, a multimodal model is developed utilizing a Boussinesq-type modal theory which is valid for small TLD fluid depths. The Bateman-Luke variational principle is employed to develop a system of coupled nonlinear ordinary differential equations which describe the fluid response when the tank is subjected to base excitation. Energy dissipation is incorporated into the model from the inclusion of damping screens. The fluid model is used to describe the response of a 2D structure-TLD system when the structure is subjected to external loading and the TLD tank geometry is irregular.

  15. TLD response to non-radiation sources

    SciTech Connect

    Ong, A. )

    1985-10-01

    A study was performed at the San Onofre Nuclear Generating Station (SONGS) to evaluate the response of personnel TLD badges to non-radiation sources commonly encountered at the station. The TLD normally used at SONGS is the four-element Panasonic Model UD802-AS2 shown on the next page. This paper reports that the non-radiation sources employed in the study consisted of two different cleaning agents, sunlight, and electric arc welding.

  16. Design of an advanced TLD-based fixed nuclear accident dosimeter

    SciTech Connect

    Casson, W.H.; Mei, G.T.

    1993-08-01

    A new system has been designed for use as a fixed nuclear accident dosimeter based upon the thermoluminescent dosimeter (TLD) system used for personnel dosimetry at US Department of Energy facilities managed by Martin Marietta Energy Systems, Inc. The system is made up of a small phantom consisting of two main parts measuring 20 x 20 x 5 cm and made from polymethylmethacrylate. A neutron-sensitive TLD card is placed in the center between the two pieces. Also, TLD cards in standard holders are mounted on the front and back of the phantom. A derivation is made of a linear combination of the responses from the TLD elements which results in calculation of the neutron fluence, absorbed dose, and dose equivalent. By using the right linear combinations, a crude spectrum can be estimated, which allows further calculation of the average fluence-to-dose-equivalent conversion factor. The response of the system was tested and found to be applicable for the evaluation of typical nuclear accident spectra, although considerable improvement can be made by the addition of a sulfur pellet. The system was also tested for angular dependence. In order to move the development of this system from the proof-of-principle to full application, the calculation of the TLD resonse curves must be improved, additional measurements must be made, and the system must be tested in a simulated accident neutron field. The advantages of the new fixed dosimeter system are its simplicity, easy maintenance, and lower operational cost. The system uses standard TLD cards that are already in place throughout Energy Systems facilities. The TLD process personnel are famliiar with evaluating doses from TLDs and can provide information necessary to ensure timely and accurate assessment of exposures that may result from riticality accidents. Most of the quality control requirements are part of the existing personnel dosimetry system.

  17. Design and Manufacturing of Extremely Low Mass Flight Systems

    NASA Technical Reports Server (NTRS)

    Johnson, Michael R.

    2002-01-01

    Extremely small flight systems pose some unusual design and manufacturing challenges. The small size of the components that make up the system generally must be built with extremely tight tolerances to maintain the functionality of the assembled item. Additionally, the total mass of the system is extremely sensitive to what would be considered small perturbations in a larger flight system. The MUSES C mission, designed, built, and operated by Japan, has a small rover provided by NASA that falls into this small flight system category. This NASA-provided rover is used as a case study of an extremely small flight system design. The issues that were encountered with the rover portion of the MUSES C program are discussed and conclusions about the recommended mass margins at different stages of a small flight system project are presented.

  18. On-board TLD measurements on MIR and ISS.

    PubMed

    Deme, S; Apáthy, I; Pázmándi, T; Benton, E R; Reitz, G; Akatov, Y

    2006-01-01

    This paper presents results from dosimetric measurements made aboard the Mir space station and the International Space Station (ISS) using the Pille portable thermoluminescent dosemeter (TLD) system. This paper includes the dosimetry mapping and automatic readout (trapped and untrapped components) results from Mir and ISS. The mean dose rate in 2001-2003 was 7 microGy h(-1). Using the hourly measuring period in automatic mode, doses from both galactic (independent of South Atlantic Anomaly--SAA) and SAA components were determined during Euromir'95 experiment. The mean total dose rate was 12.5 microGy h(-1), while the SAA contribution was 6.2 microGy h(-1). A similar measurement was performed on ISS in 2001 and in 2003. Both the manual and automatic measurements show a significant decrease in dose rate in 2001 in comparison to 1995-1997 due to the change in solar activity. For determination of the high linear energy transfer contribution from the radiation field during the ISS mapping experiment, three CR-39 plastic nuclear track detectors (PNTDs) were co-located with each TL detector. Analysis of the combined TLD and PNTD measurements showed a typical mean TLD efficiency of 84%, a dose contribution <10 keV microm(-1) of 17%, and an average quality factor of 1.95. PMID:16709717

  19. Calibration of an automatic TLD irradiator

    SciTech Connect

    Jang, J.C.; Pasciak, W.J. )

    1987-07-01

    The Panasonic UD-801 TLDs used in the U.S. Nuclear Regulatory Commission's environmental monitoring program are calibrated using the Williston Elin Model 2001 Irradiator. This article describes the procedure used to calibrate this irradiator for the delivery of exposures in the range of 40 to 1200 mR. A select group of TLDs, another source, and an NBS-calibrated ion chamber were used to perform a secondary calibration of the WE-2001. Extraneous exposure contributions (background radiation from the irradiator's source and exposure occurring during TLD travel into and out of the irradiation chamber) were measured and evaluated. The WE-2001 TLD Irradiator was calibrated to a total uncertainty of {plus minus}3.2%; however, TLD travel time exposures were found to be quite significant for the short irradiation times typically used in environmental applications.

  20. Spectrometer system for diffuse extreme ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Labov, Simon E.

    1989-01-01

    A unique grazing incidence spectrometer system has been designed to study diffuse line emission between 80 and 650 A with 10-30 A resolution. The minimum detectable emission line strength during a 5-min observation ranges from 100-2000 ph/sq cm sec str. The instrument uses mechanically ruled reflection gratings placed in front of a linear array of mirrors. These mirrors focus the spectral image on microchannel plate detectors located behind thin filters. The field of view is 40 min of arc by 15 deg, and there is no spatial imaging. This instrument has been fabricated, calibrated, and successfully flown on a sounding rocket to observe the astronomical background radiation.

  1. Weather in an extremely nearby substellar system

    NASA Astrophysics Data System (ADS)

    Buenzli, Esther; Marley, Mark; Apai, Daniel; Biller, Beth; Crossfield, Ian; Radigan, Jacqueline

    2015-12-01

    At a distance of only 2 pc, the brown dwarf binary WISE J104915.57-531906.1, also known as Luhman 16AB, is the third closest system from the Sun. As the closest substellar objects outside of the solar system, their unusual brightness makes these brown dwarfs of late-L and early-T spectral type a unique laboratory for the study of ultracool atmospheres. Their effective temperatures are very similar to those of directly imaged planets such as the HR8799 planets, and they share many atmospheric properties. Without a bright host star, the brown dwarf atmospheres can be studied in much greater detail. In particular, time-resolved spectroscopic observations have recently started to be used to provide new insights into heterogeneities in the cloud structure of brown dwarfs. Luhman 16B was the first brown dwarf to be mapped with Doppler Imaging, which resulted in a surface map with darker and brighter spots that may relate to different cloud features. We have now obtained spectroscopic time series with HST/WFC3 that allow us to measure the absolute flux changes over a broad wavelength range (0.8 - 1.7 microns) and cover several molecular and atomic absorption features, including for the first time the FeH feature that has been thought to be a good tracer of cloud holes. Because we detect significant variability in both Luhman 16A and B, effectively observing weather on these nearby worlds, we can for the first time directly characterize and compare the heterogeneous cloud structure in a co-eval L/T transition binary. The observations provide important insight into how clouds evolve and disappear across the L/T transition at ~1200 K, and the results are also very relevant for the interpretation of spectra of young directly imaged giant planets.

  2. Cutaneous Markers of Systemic Disease in the Lower Extremity.

    PubMed

    Vella, Joseph

    2016-07-01

    The skin of the lower extremity can be a helpful diagnostic tool for systemic disease. Diabetes, renal disease, genetic disorders, and even cancer can have cutaneous manifestations in the legs and feet; moreover, proper diagnosis can facilitate earlier treatment of these diseases and not only clear up the skin symptoms but also bring about resolution of the systemic disease causing them. Although not comprehensive, this article discusses many of these disorders presenting with integumentary manifestations in the lower extremities. Where appropriate, it also enumerates the treatments involved, both systemic and localized. PMID:27215161

  3. Surface dose measurement using TLD powder extrapolation

    SciTech Connect

    Rapley, P. . E-mail: rapleyp@tbh.net

    2006-10-01

    Surface/near-surface dose measurements in therapeutic x-ray beams are important in determining the dose to the dermal and epidermal skin layers during radiation treatment. Accurate determination of the surface dose is a difficult but important task for proper treatment of patients. A new method of measuring surface dose in phantom through extrapolation of readings from various thicknesses of thermoluminescent dosimeter (TLD) powder has been developed and investigated. A device was designed, built, and tested that provides TLD powder thickness variation to a minimum thickness of 0.125 mm. Variations of the technique have been evaluated to optimize precision with consideration of procedural ease. Results of this study indicate that dose measurements (relative to D{sub max}) in regions of steep dose gradient in the beam axis direction are possible with a precision (2 standard deviations [SDs]) as good as {+-} 1.2% using the technique. The dosimeter was developed and evaluated using variation to the experimental method. A clinically practical procedure was determined, resulting in measured surface dose of 20.4 {+-} 2% of the D{sub max} dose for a 10 x 10 cm{sup 2}, 80-cm source-to-surface distance (SSD), Theratron 780 Cobalt-60 ({sup 60}C) beam. Results obtained with TLD powder extrapolation compare favorably to other methods presented in the literature. The TLD powder extrapolation tool has been used clinically at the Northwestern Ontario Regional Cancer Centre (NWORCC) to measure surface dose effects under a number of conditions. Results from these measurements are reported. The method appears to be a simple and economical tool for surface dose measurement, particularly for facilities with TLD powder measurement capabilities.

  4. Comparison of environmental TLD (thermoluminescent dosimeter) results obtained using glow curve deconvolution and region of interest analysis

    SciTech Connect

    Not Available

    1987-01-01

    We tested a Harshaw Model 4000 TLD Reader in the Sandia Environmental TLD Program. An extra set of LiF TLD-700 chips were prepared for each field location and calibration level. At the end of quarter one, half of the TLDs were read on the Model 4000 and the other half were read on our standard Harshaw Model 2000. This presentation compares the results of the two systems. The Model 4000 results are reported for two regions of interest and for background subtraction using Harshaw Glow Curve Deconvolution Software.

  5. AN EXTREMELY CARBON-RICH, EXTREMELY METAL-POOR STAR IN THE SEGUE 1 SYSTEM

    SciTech Connect

    Norris, John E.; Yong, David; Gilmore, Gerard; Wyse, Rosemary F. G.; Frebel, Anna

    2010-10-10

    We report the analysis of high-resolution, high signal-to-noise ratio, spectra of an extremely metal-poor, extremely C-rich red giant, Seg 1-7, in Segue 1-described in the literature alternatively as an unusually extended globular cluster or an ultra-faint dwarf galaxy. The radial velocity of Seg 1-7 coincides precisely with the systemic velocity of Segue 1, and its chemical abundance signature of [Fe/H] = -3.52, [C/Fe] = +2.3, [N/Fe] = +0.8, [Na/Fe] = +0.53, [Mg/Fe] = +0.94, [Al/Fe] = +0.23, and [Ba/Fe] < -1.0 is similar to that of the rare and enigmatic class of Galactic halo objects designated CEMP-no (carbon-rich, extremely metal-poor with no enhancement (over solar ratios) of heavy neutron-capture elements). This is the first star in a Milky Way 'satellite' that unambiguously lies on the metal-poor, C-rich branch of the Aoki et al. bimodal distribution of field halo stars in the ([C/Fe], [Fe/H])-plane. Available data permit us only to identify Seg 1-7 as a member of an ultra-faint dwarf galaxy or as debris from the Sgr dwarf spheroidal galaxy. In either case, this demonstrates that at extremely low abundance, [Fe/H ] <-3.0, star formation and associated chemical evolution proceeded similarly in the progenitors of both the field halo and satellite systems. By extension, this is consistent with other recent suggestions that the most metal-poor dwarf spheroidal and ultra-faint dwarf satellites were the building blocks of the Galaxy's outer halo.

  6. Neutron/gamma dose characterization for use with TLD

    SciTech Connect

    Kee, J.C.; Magee, L.; Hefley, T.

    1991-01-01

    The work described in this paper was performed in preparation for establishing a thermoluminescent dosimetry (TLD) system for workers exposed to spontaneous fission neutrons from mixed plutonium isotopes, {sup 232}Th, and depleted uranium at the US Department of Energy (DOE) Pantex facility. The method proposed uses a neutron-insensitive thermoluminescent dosimeter to measure the gamma dose and apply a neutron dose/gamma dose ratio to calculate the neutron dose equivalent. This approach, while requiring multibadge dosimetry for each individual, provides a more accurate neutron dose calculation than was previously in use and reduces the maximum missed dose and falsely reported dose.

  7. Robust neighboring extremal guidance for the advanced launch system

    NASA Technical Reports Server (NTRS)

    Bain, John; Speyer, Jason L.

    1993-01-01

    With the availability of modern flight computers, realtime neighboring extremal guidance seems feasible. To overcome sensitivity to unknown system parameters and environmental uncertainties, a robust neighboring extremal guidance scheme is proposed. About the optimal trajectory, the accessory problem in the calculus of variations is formed, generating a quadratic cost criterion in the perturbed states and controls. By formulating a disturbance attenuation problem based upon the second variation cost criterion, a differential game is formulated. The game theoretic cost criterion is minimized with respect to the perturbed control but maximized with respect to the unknown parameters in the linearized dynamics. The resulting differential game problem gives rise to a two-point boundary-value problem solved using the sweep method. The sweep method solution provides a linear robust neighboring extremal guidance scheme that is applied to the Advanced Launch System.

  8. Response of Simple, Model Systems to Extreme Conditions

    SciTech Connect

    Ewing, Rodney C.; Lang, Maik

    2015-07-30

    The focus of the research was on the application of high-pressure/high-temperature techniques, together with intense energetic ion beams, to the study of the behavior of simple oxide systems (e.g., SiO2, GeO2, CeO2, TiO2, HfO2, SnO2, ZnO and ZrO2) under extreme conditions. These simple stoichiometries provide unique model systems for the analysis of structural responses to pressure up to and above 1 Mbar, temperatures of up to several thousands of kelvin, and the extreme energy density generated by energetic heavy ions (tens of keV/atom). The investigations included systematic studies of radiation- and pressure-induced amorphization of high P-T polymorphs. By studying the response of simple stoichiometries that have multiple structural “outcomes”, we have established the basic knowledge required for the prediction of the response of more complex structures to extreme conditions. We especially focused on the amorphous state and characterized the different non-crystalline structure-types that result from the interplay of radiation and pressure. For such experiments, we made use of recent technological developments, such as the perforated diamond-anvil cell and in situ investigation using synchrotron x-ray sources. We have been particularly interested in using extreme pressures to alter the electronic structure of a solid prior to irradiation. We expected that the effects of modified band structure would be evident in the track structure and morphology, information which is much needed to describe theoretically the fundamental physics of track-formation. Finally, we investigated the behavior of different simple-oxide, composite nanomaterials (e.g., uncoated nanoparticles vs. core/shell systems) under coupled, extreme conditions. This provided insight into surface and boundary effects on phase stability under extreme conditions.

  9. Terrestrial Applications of Extreme Environment Stirling Space Power Systems

    NASA Technical Reports Server (NTRS)

    Dyson, Rodger. W.

    2012-01-01

    NASA has been developing power systems capable of long-term operation in extreme environments such as the surface of Venus. This technology can use any external heat source to efficiently provide electrical power and cooling; and it is designed to be extremely efficient and reliable for extended space missions. Terrestrial applications include: use in electric hybrid vehicles; distributed home co-generation/cooling; and quiet recreational vehicle power generation. This technology can reduce environmental emissions, petroleum consumption, and noise while eliminating maintenance and environmental damage from automotive fluids such as oil lubricants and air conditioning coolant. This report will provide an overview of this new technology and its applications.

  10. Multivariate analysis of TLD orientation effects

    SciTech Connect

    Archer, B.R.; Bushong, S.C.; Thornby, J.I.

    1980-07-01

    The effect of orientation on extruded thermoluminescent dosimeters has been investigated. TLD's placed on the surface and within a phantom were exposed separately to five diagnostic beam qualities and to /sup 60/Co ..gamma.. rays. The resulting data were subjected to analysis of variance and examined for significant correlations. The response of dosimeters on the phantom surface varied with orientation and was energy dependent. In the phantom and with /sup 60/Co, no orientation effects were observed.

  11. Improvement of Accuracy in Environmental Dosimetry by TLD Cards Using Three-dimensional Calibration Method

    PubMed Central

    HosseiniAliabadi, S. J.; Hosseini Pooya, S. M.; Afarideh, H.; Mianji, F.

    2015-01-01

    Introduction The angular dependency of response for TLD cards may cause deviation from its true value on the results of environmental dosimetry, since TLDs may be exposed to radiation at different angles of incidence from the surrounding area. Objective A 3D setting of TLD cards has been calibrated isotropically in a standard radiation field to evaluate the improvement of the accuracy of measurement for environmental dosimetry. Method Three personal TLD cards were rectangularly placed in a cylindrical holder, and calibrated using 1D and 3D calibration methods. Then, the dosimeter has been used simultaneously with a reference instrument in a real radiation field measuring the accumulated dose within a time interval. Result The results show that the accuracy of measurement has been improved by 6.5% using 3D calibration factor in comparison with that of normal 1D calibration method. Conclusion This system can be utilized in large scale environmental monitoring with a higher accuracy. PMID:26157729

  12. SU-E-T-308: Systematic Characterization of the Energy Response of Different LiF TLD Crystals for Dosimetry Applications

    SciTech Connect

    Pena, E; Caprile, P; Sanchez-Nieto, B

    2014-06-01

    Purpose: The thermoluminiscense dosimeters (TLDs) are widely used in personal and clinical dosimetry due to its small size, good sensitivity and tissue equivalence, among other advantages. This study presents the characterization of Lithium Fluoride based TLDs, in terms of their absorbed dose response to successive irradiation cycles in a broad range of beam energies, measured under reference conditions. Methods: Four types of Harshaw TLD chips were used: TLD-100, TLD-600 TLD-700 and 100-H. They were irradiated with 10 photon beams of different energy spectrums, from 28 kVp to 18MV (in 30 consecutive cycles for 6 and 18 MV). Results: It was found that the response of the dosimetric system was stabilized (less than ±3%) after 10 cycles for TLD-600 and TLD-700. In the case of TLD-100 and TLD-100H this dependence was not observed. A decreased response to increasing beam energy in terms of absorbed dose to water was observed, as expected, except for TLD-100H which showed the opposite behavior. The less energy dependent detector was the TLD-100H exhibiting a maximum deviation of 12%. The highest variation observed was 33% for TLD-100. The study allowed the determination of calibration factors in absorbed dose for a wide range of energies and materials for different dosimetric applications, such as in-vivo dosimetry during imaging and radiotherapy. Conclusion: The study allowed the determination of calibration factors in absorbed dose for a wide range of energies and materials for different dosimetric applications, such as in-vivo dosimetry during imaging and radiotherapy.

  13. In vivo TLD dose measurements in catheter-based high-dose-rate brachytherapy.

    PubMed

    Adlienė, Diana; Jakštas, Karolis; Urbonavičius, Benas Gabrielis

    2015-07-01

    Routine in vivo dosimetry is well established in external beam radiotherapy; however, it is restricted mainly to detection of gross errors in high-dose-rate (HDR) brachytherapy due to complicated measurements in the field of steep dose gradients in the vicinity of radioactive source and high uncertainties. The results of in vivo dose measurements using TLD 100 mini rods and TLD 'pin worms' in catheter-based HDR brachytherapy are provided in this paper alongside with their comparison with corresponding dose values obtained using calculation algorithm of the treatment planning system. Possibility to perform independent verification of treatment delivery in HDR brachytherapy using TLDs is discussed. PMID:25809111

  14. Organ radiation exposure with EOS: GATE simulations versus TLD measurements

    NASA Astrophysics Data System (ADS)

    Clavel, A. H.; Thevenard-Berger, P.; Verdun, F. R.; Létang, J. M.; Darbon, A.

    2016-03-01

    EOS® is an innovative X-ray imaging system allowing the acquisition of two simultaneous images of a patient in the standing position, during the vertical scan of two orthogonal fan beams. This study aimed to compute organs radiation exposure to a patient, in the particular geometry of this system. Two different positions of the patient in the machine were studied, corresponding to postero-anterior plus left lateral projections (PA-LLAT) and antero-posterior plus right lateral projections (AP-RLAT). To achieve this goal, a Monte-Carlo simulation was developed based on a GATE environment. To model the physical properties of the patient, a computational phantom was produced based on computed tomography scan data of an anthropomorphic phantom. The simulations provided several organs doses, which were compared to previously published dose results measured with Thermo Luminescent Detectors (TLD) in the same conditions and with the same phantom. The simulation results showed a good agreement with measured doses at the TLD locations, for both AP-RLAT and PA-LLAT projections. This study also showed that the organ dose assessed only from a sample of locations, rather than considering the whole organ, introduced significant bias, depending on organs and projections.

  15. A TLD dose algorithm using artificial neural networks

    SciTech Connect

    Moscovitch, M.; Rotunda, J.E.; Tawil, R.A.; Rathbone, B.A.

    1995-12-31

    An artificial neural network was designed and used to develop a dose algorithm for a multi-element thermoluminescence dosimeter (TLD). The neural network architecture is based on the concept of functional links network (FLN). Neural network is an information processing method inspired by the biological nervous system. A dose algorithm based on neural networks is fundamentally different as compared to conventional algorithms, as it has the capability to learn from its own experience. The neural network algorithm is shown the expected dose values (output) associated with given responses of a multi-element dosimeter (input) many times. The algorithm, being trained that way, eventually is capable to produce its own unique solution to similar (but not exactly the same) dose calculation problems. For personal dosimetry, the output consists of the desired dose components: deep dose, shallow dose and eye dose. The input consists of the TL data obtained from the readout of a multi-element dosimeter. The neural network approach was applied to the Harshaw Type 8825 TLD, and was shown to significantly improve the performance of this dosimeter, well within the U.S. accreditation requirements for personnel dosimeters.

  16. Extreme event statistics of daily rainfall: dynamical systems approach

    NASA Astrophysics Data System (ADS)

    Cigdem Yalcin, G.; Rabassa, Pau; Beck, Christian

    2016-04-01

    We analyse the probability densities of daily rainfall amounts at a variety of locations on Earth. The observed distributions of the amount of rainfall fit well to a q-exponential distribution with exponent q close to q≈ 1.3. We discuss possible reasons for the emergence of this power law. In contrast, the waiting time distribution between rainy days is observed to follow a near-exponential distribution. A careful investigation shows that a q-exponential with q≈ 1.05 yields the best fit of the data. A Poisson process where the rate fluctuates slightly in a superstatistical way is discussed as a possible model for this. We discuss the extreme value statistics for extreme daily rainfall, which can potentially lead to flooding. This is described by Fréchet distributions as the corresponding distributions of the amount of daily rainfall decay with a power law. Looking at extreme event statistics of waiting times between rainy days (leading to droughts for very long dry periods) we obtain from the observed near-exponential decay of waiting times extreme event statistics close to Gumbel distributions. We discuss superstatistical dynamical systems as simple models in this context.

  17. High numerical aperture projection system for extreme ultraviolet projection lithography

    DOEpatents

    Hudyma, Russell M.

    2000-01-01

    An optical system is described that is compatible with extreme ultraviolet radiation and comprises five reflective elements for projecting a mask image onto a substrate. The five optical elements are characterized in order from object to image as concave, convex, concave, convex, and concave mirrors. The optical system is particularly suited for ring field, step and scan lithography methods. The invention uses aspheric mirrors to minimize static distortion and balance the static distortion across the ring field width which effectively minimizes dynamic distortion. The present invention allows for higher device density because the optical system has improved resolution that results from the high numerical aperture, which is at least 0.14.

  18. A combined TLD/emulsion method of sampling dosimetry applied to Apollo missions

    NASA Technical Reports Server (NTRS)

    Schaefer, H. J.

    1979-01-01

    A system which simplifies the complex monitoring methods used to measure the astronaut's radiation exposure in space is proposed. The excess dose equivalents of trapped protons and secondary neutrons, protons, and alpha particles from local nuclear interactions are determined and a combined thermoluminescent dosimeter (TLD)/nuclear emulsion method which measures the absorbed dose with thermoluminescent dosimeter chips is presented.

  19. High latitude equivalent current systems during extremely quiet times

    NASA Technical Reports Server (NTRS)

    Rostoker, G.; Chen, A. J.; Yasuhara, F.; Akasofu, S.-I.; Kawasaki, K.

    1974-01-01

    The magnetic perturbation patterns in the polar cap and auroral zone regions are obtained for extremely quiet days using two different techniques. It is shown that the form of the equivalent current flow pattern is extremely sensitive to the level of quietness, and that even so-called quiet days are at times disturbed by substorm activity. Certain characteristic equivalent flow not typically observed during substorms is noted in the polar cap, and this flow appears to be associated with effects of polar cap perturbations discussed by Svalgaard (1973). A region of equatorward flow at high latitudes near the dawn meridian, appears to be Hall current driven by an eastward electric field. The dayside sub-auroral zone is dominated by the Sq-current system, while the nightside shows no significant current flow in the absence of substorm activity.

  20. Skin dose measurements using MOSFET and TLD for head and neck patients treated with tomotherapy.

    PubMed

    Kinhikar, Rajesh A; Murthy, Vedang; Goel, Vineeta; Tambe, Chandrashekar M; Dhote, Dipak S; Deshpande, Deepak D

    2009-09-01

    The purpose of this work was to estimate skin dose for the patients treated with tomotherapy using metal oxide semiconductor field-effect transistors (MOSFETs) and thermoluminescent dosimeters (TLDs). In vivo measurements were performed for two head and neck patients treated with tomotherapy and compared to TLD measurements. The measurements were subsequently carried out for five days to estimate the inter-fraction deviations in MOSFET measurements. The variation between skin dose measured with MOSFET and TLD for first patient was 2.2%. Similarly, the variation of 2.3% was observed between skin dose measured with MOSFET and TLD for second patient. The tomotherapy treatment planning system overestimated the skin dose as much as by 10-12% when compared to both MOSFET and TLD. However, the MOSFET measured patient skin doses also had good reproducibility, with inter-fraction deviations ranging from 1% to 1.4%. MOSFETs may be used as a viable dosimeter for measuring skin dose in areas where the treatment planning system may not be accurate. PMID:19369084

  1. Development of an algorithm for TLD badge system for dosimetry in the field of X and gamma radiation in terms of Hp(10).

    PubMed

    Bakshi, A K; Srivastava, K; Varadharajan, G; Pradhan, A S; Kher, R K

    2007-01-01

    In view of the introduction of International Commission on Radiation Units and Measurements operational quantities Hp(10) and Hp(0.07), defined for individual monitoring, it became necessary to develop an algorithm that gives direct response of the dosemeter in terms of the operational quantities. Hence, for this purpose and also to improve the accuracy in dose estimation especially in the mixed fields of X ray and gamma, an algorithm was developed based on higher-order polynomial fit of the data points generated from the dose-response of discs under different filter regions of the present TL dosemeter system for known delivered doses. Study on the response of the BARC TL dosemeter system based on CaSO(4):Dy Teflon thermoluminescence dosemeter discs in the mixed fields of X and gamma radiation was carried out to ensure that the accuracies are within the prescribed limits recommended by the international organisations. The prevalent algorithm, based on the ratios of the disc response under various filters regions of the dosemeter to pure photons, was tested for different proportion of two radiations in case of mixed field dosimetry. It was found that the accuracy for few fields is beyond the acceptable limit in case of prevalent algorithm. The new proposed algorithm was also tested in mixed fields of photon fields and to pure photon fields of varied angles. It was found that the response of the dosemeter in mixed fields of photons and its angular response are satisfactory. The new algorithm can be used to record and report the personal dose in terms of Hp(10) as per the international recommendation for the present TL dosemeter. PMID:16984896

  2. Assessment of the dose distribution inside a cardiac cath lab using TLD measurements and Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Baptista, M.; Teles, P.; Cardoso, G.; Vaz, P.

    2014-11-01

    Over the last decade, there was a substantial increase in the number of interventional cardiology procedures worldwide, and the corresponding ionizing radiation doses for both the medical staff and patients became a subject of concern. Interventional procedures in cardiology are normally very complex, resulting in long exposure times. Also, these interventions require the operator to work near the patient and, consequently, close to the primary X-ray beam. Moreover, due to the scattered radiation from the patient and the equipment, the medical staff is also exposed to a non-uniform radiation field that can lead to a significant exposure of sensitive body organs and tissues, such as the eye lens, the thyroid and the extremities. In order to better understand the spatial variation of the dose and dose rate distributions during an interventional cardiology procedure, the dose distribution around a C-arm fluoroscopic system, in operation in a cardiac cath lab at Portuguese Hospital, was estimated using both Monte Carlo (MC) simulations and dosimetric measurements. To model and simulate the cardiac cath lab, including the fluoroscopic equipment used to execute interventional procedures, the state-of-the-art MC radiation transport code MCNPX 2.7.0 was used. Subsequently, Thermo-Luminescent Detector (TLD) measurements were performed, in order to validate and support the simulation results obtained for the cath lab model. The preliminary results presented in this study reveal that the cardiac cath lab model was successfully validated, taking into account the good agreement between MC calculations and TLD measurements. The simulated results for the isodose curves related to the C-arm fluoroscopic system are also consistent with the dosimetric information provided by the equipment manufacturer (Siemens). The adequacy of the implemented computational model used to simulate complex procedures and map dose distributions around the operator and the medical staff is discussed, in

  3. Development of a technique for improving coefficient of variation of CaSO4:Dy teflon-based TLD personnel monitoring system in low-dose region.

    PubMed

    Pradhan, S M; Sneha, C; Sahai, M K; Chougaonkar, M P; Babu, D A R

    2015-12-01

    In view of the importance of zero-dose background (null signal) in influencing the coefficient of variation in low-dose region, a technique for the estimation of the same from composite (gross) signal is developed for CaSO4:Dy-based personnel monitoring system being used in India. The technique is based on simple analysis of glow curves (GCs) of unexposed and exposed dosemeters, evolution of trend/model for the zero-dose curves, generation of simulation protocol for individual zero-dose curves, establishment of characteristics of GCs of exposed dosemeters and finally preparation of an algorithm to segregate the components from composite signal. The technique offers the separation of real-time background and gives superior results over other method of approximation of the background. The results also prove efficiency of the empirical trending and simulation protocol of background GCs. The proposed technique can be implemented in routine monitoring without any extra man hours and reader time. PMID:25527179

  4. Hydroclimatic Extremes: Inferences and Prediction from a Dynamical Systems Perspective

    NASA Astrophysics Data System (ADS)

    Lall, U.

    2015-12-01

    Hydroclimatic extremes , such as major floods and droughts, or periods with a high frequency of clustered tornadoes, fires or cyclones, have often been thought of as random, rare events, and much of the literature on these topics has been obsessed with the estimation of the tail probabilities (e.g., the 100 year event) of these processes. It has taken the "acceptance" of the notion of climate change to question whether the machinery developed for such estimation or even the associated questions are reasonable. However, much of the literature that has evolved since has focused on how to detect and model changes in these probabilities using a variety of methods. In this talk, I will argue that while such efforts may be useful in a certain, outdated context, they are not necessarily leading to an improvement in eihter the science of the application of the science to disaster risk mitigation. I develop an argument that hydroclimatic extremes result from an organization of the associated global and local dynamical systems that leads to the systems trajectories locking into a particular region of state space. Such excursions could be considered as rare events, in their ultimate expression, or in their frequency of visitation and persistence in those states. An open question is whether the dynamics of the system under such conditions are marked by high or low predictabilty in the Lyapunov sense. A characterization of the dimension and predictability of hydroclimatic extremes would allow us to better understand the potential implications of climate change, and also of whether or not a regional drought or similar persistent regime is likely to dissipate or grow.

  5. Wireless pilot monitoring system for extreme race conditions.

    PubMed

    Pino, Esteban J; Arias, Diego E; Aqueveque, Pablo; Melin, Pedro; Curtis, Dorothy W

    2012-01-01

    This paper presents the design and implementation of an assistive device to monitor car drivers under extreme conditions. In particular, this system is designed in preparation for the 2012 Atacama Solar Challenge to be held in the Chilean desert. Actual preliminary results show the feasibility of such a project including physiological and ambient sensors, real-time processing algorithms, wireless data transmission and a remote monitoring station. Implementation details and field results are shown along with a discussion of the main problems found in real-life telemetry monitoring. PMID:23367054

  6. Reducing Waste in Extreme Scale Systems through Introspective Analysis

    SciTech Connect

    Bautista-Gomez, Leonardo; Gainaru, Ana; Perarnau, Swann; Engelmann, Christian; Cappello, Franck; Snir, Marc

    2016-01-01

    Resilience is an important challenge for extreme- scale supercomputers. Today, failures in supercomputers are assumed to be uniformly distributed in time. However, recent studies show that failures in high-performance computing systems are partially correlated in time, generating periods of higher failure density. Our study of the failure logs of multiple supercomputers show that periods of higher failure density occur with up to three times more than the average. We design a monitoring system that listens to hardware events and forwards important events to the runtime to detect those regime changes. We implement a runtime capable of receiving notifications and adapt dynamically. In addition, we build an analytical model to predict the gains that such dynamic approach could achieve. We demonstrate that in some systems, our approach can reduce the wasted time by over 30%.

  7. The Potential of Extreme Adaptive Optics Systems for Asteroid Studies

    NASA Astrophysics Data System (ADS)

    Marchis, F.; Vega, D.

    2014-12-01

    New Adaptive optics (AO) systems, called Extreme AO systemsare becoming available this year on two 8m-class telescopes. Both the Gemini Planet Imager (GPI) on the Gemini South Telescope and SPHERE on the Very Large Telescope provide an almost perfect correction of the atmospheric turbulences and are equipped with low-resolution integral field spectrograph and a polarimeter. We will present the analysis of observations of (2) Pallas which was observed with GPI in direct imaging (without coronagraph) on March 22 2014 in Y, J, H, and K1 filters (from 0.95 to 2.19 μm) spectroscopically with a resolution varying from 34 to 70. The 540-km asteroid is well resolved and irregular. An ellipse of 540±9 mas and 470±9 mas fits its silhouette. The surface of the asteroid is mostly featureless but small differences of colors is currently being analyzed. No moons with a diameter larger than 0.5 km and at less than 1.2" were detected on these observations. We will discuss the future contributions of these Extreme AO systems, including SPHERE most recent observations, for the study of large main-belt asteroids addressing the number of targets that can be observed and comparing their on-sky efficiency with previous AO systems. Key scientific questions such as the possible differentiation of the primary of multiple asteroids (e.g. 45 Eugenia by Beauvalet and Marchis, Icarus, 2014 or 87 Sylvia in Berthier et al., Icarus, 2014), and the origin of these systems by comparison of the color of the moons and the primary (e.g. Marchis et al., AGU 2013) could be answered through intensive surveys conducted with these new AO systems.

  8. Predictability of extremes in non-linear hierarchically organized systems

    NASA Astrophysics Data System (ADS)

    Kossobokov, V. G.; Soloviev, A.

    2011-12-01

    Understanding the complexity of non-linear dynamics of hierarchically organized systems progresses to new approaches in assessing hazard and risk of the extreme catastrophic events. In particular, a series of interrelated step-by-step studies of seismic process along with its non-stationary though self-organized behaviors, has led already to reproducible intermediate-term middle-range earthquake forecast/prediction technique that has passed control in forward real-time applications during the last two decades. The observed seismic dynamics prior to and after many mega, great, major, and strong earthquakes demonstrate common features of predictability and diverse behavior in course durable phase transitions in complex hierarchical non-linear system of blocks-and-faults of the Earth lithosphere. The confirmed fractal nature of earthquakes and their distribution in space and time implies that many traditional estimations of seismic hazard (from term-less to short-term ones) are usually based on erroneous assumptions of easy tractable analytical models, which leads to widespread practice of their deceptive application. The consequences of underestimation of seismic hazard propagate non-linearly into inflicted underestimation of risk and, eventually, into unexpected societal losses due to earthquakes and associated phenomena (i.e., collapse of buildings, landslides, tsunamis, liquefaction, etc.). The studies aimed at forecast/prediction of extreme events (interpreted as critical transitions) in geophysical and socio-economical systems include: (i) large earthquakes in geophysical systems of the lithosphere blocks-and-faults, (ii) starts and ends of economic recessions, (iii) episodes of a sharp increase in the unemployment rate, (iv) surge of the homicides in socio-economic systems. These studies are based on a heuristic search of phenomena preceding critical transitions and application of methodologies of pattern recognition of infrequent events. Any study of rare

  9. Four-mirror extreme ultraviolet (EUV) lithography projection system

    DOEpatents

    Cohen, Simon J; Jeong, Hwan J; Shafer, David R

    2000-01-01

    The invention is directed to a four-mirror catoptric projection system for extreme ultraviolet (EUV) lithography to transfer a pattern from a reflective reticle to a wafer substrate. In order along the light path followed by light from the reticle to the wafer substrate, the system includes a dominantly hyperbolic convex mirror, a dominantly elliptical concave mirror, spherical convex mirror, and spherical concave mirror. The reticle and wafer substrate are positioned along the system's optical axis on opposite sides of the mirrors. The hyperbolic and elliptical mirrors are positioned on the same side of the system's optical axis as the reticle, and are relatively large in diameter as they are positioned on the high magnification side of the system. The hyperbolic and elliptical mirrors are relatively far off the optical axis and hence they have significant aspherical components in their curvatures. The convex spherical mirror is positioned on the optical axis, and has a substantially or perfectly spherical shape. The spherical concave mirror is positioned substantially on the opposite side of the optical axis from the hyperbolic and elliptical mirrors. Because it is positioned off-axis to a degree, the spherical concave mirror has some asphericity to counter aberrations. The spherical concave mirror forms a relatively large, uniform field on the wafer substrate. The mirrors can be tilted or decentered slightly to achieve further increase in the field size.

  10. A millisecond pulsar in an extremely wide binary system

    NASA Astrophysics Data System (ADS)

    Bassa, C. G.; Janssen, G. H.; Stappers, B. W.; Tauris, T. M.; Wevers, T.; Jonker, P. G.; Lentati, L.; Verbiest, J. P. W.; Desvignes, G.; Graikou, E.; Guillemot, L.; Freire, P. C. C.; Lazarus, P.; Caballero, R. N.; Champion, D. J.; Cognard, I.; Jessner, A.; Jordan, C.; Karuppusamy, R.; Kramer, M.; Lazaridis, K.; Lee, K. J.; Liu, K.; Lyne, A. G.; McKee, J.; Osłowski, S.; Perrodin, D.; Sanidas, S.; Shaifullah, G.; Smits, R.; Theureau, G.; Tiburzi, C.; Zhu, W. W.

    2016-08-01

    We report on 22 yrs of radio timing observations of the millisecond pulsar J1024$-$0719 by the telescopes participating in the European Pulsar Timing Array (EPTA). These observations reveal a significant second derivative of the pulsar spin frequency and confirm the discrepancy between the parallax and Shklovskii distances that has been reported earlier. We also present optical astrometry, photometry and spectroscopy of 2MASS J10243869$-$0719190. We find that it is a low-metallicity main-sequence star (K7V spectral type, $\\mathrm{[M/H]}=-1.0$, $T_\\mathrm{eff}=4050\\pm50$ K) and that its position, proper motion and distance are consistent with those of PSR J1024$-$0719. We conclude that PSR J1024$-$0719 and 2MASS J10243869$-$0719190 form a common proper motion pair and are gravitationally bound. The gravitational interaction between the main-sequence star and the pulsar accounts for the spin frequency derivatives, which in turn resolves the distance discrepancy. Our observations suggest that the pulsar and main-sequence star are in an extremely wide ($P_\\mathrm{b}>200$ yr) orbit. Combining the radial velocity of the companion and proper motion of the pulsar, we find that the binary system has a high spatial velocity of $384\\pm45$ km s$^{-1}$ with respect to the local standard of rest and has a Galactic orbit consistent with halo objects. Since the observed main-sequence companion star cannot have recycled the pulsar to millisecond spin periods, an exotic formation scenario is required. We demonstrate that this extremely wide-orbit binary could have evolved from a triple system that underwent an asymmetric supernova explosion, though find that significant fine-tuning during the explosion is required. Finally, we discuss the implications of the long period orbit on the timing stability of PSR J1024$-$0719 in light of its inclusion in pulsar timing arrays.

  11. A millisecond pulsar in an extremely wide binary system

    NASA Astrophysics Data System (ADS)

    Bassa, C. G.; Janssen, G. H.; Stappers, B. W.; Tauris, T. M.; Wevers, T.; Jonker, P. G.; Lentati, L.; Verbiest, J. P. W.; Desvignes, G.; Graikou, E.; Guillemot, L.; Freire, P. C. C.; Lazarus, P.; Caballero, R. N.; Champion, D. J.; Cognard, I.; Jessner, A.; Jordan, C.; Karuppusamy, R.; Kramer, M.; Lazaridis, K.; Lee, K. J.; Liu, K.; Lyne, A. G.; McKee, J.; Osłowski, S.; Perrodin, D.; Sanidas, S.; Shaifullah, G.; Smits, R.; Theureau, G.; Tiburzi, C.; Zhu, W. W.

    2016-08-01

    We report on 22 yr of radio timing observations of the millisecond pulsar J1024-0719 by the telescopes participating in the European Pulsar Timing Array (EPTA). These observations reveal a significant second derivative of the pulsar spin frequency and confirm the discrepancy between the parallax and Shklovskii distances that has been reported earlier. We also present optical astrometry, photometry and spectroscopy of 2MASS J10243869-0719190. We find that it is a low-metallicity main-sequence star (K7V spectral type, [M/H] = -1.0, Teff = 4050 ± 50 K) and that its position, proper motion and distance are consistent with those of PSR J1024-0719. We conclude that PSR J1024-0719 and 2MASS J10243869-0719190 form a common proper motion pair and are gravitationally bound. The gravitational interaction between the main-sequence star and the pulsar accounts for the spin frequency derivatives, which in turn resolves the distance discrepancy. Our observations suggest that the pulsar and main-sequence star are in an extremely wide (Pb > 200 yr) orbit. Combining the radial velocity of the companion and proper motion of the pulsar, we find that the binary system has a high spatial velocity of 384 ± 45 km s-1 with respect to the local standard of rest and has a Galactic orbit consistent with halo objects. Since the observed main-sequence companion star cannot have recycled the pulsar to millisecond spin periods, an exotic formation scenario is required. We demonstrate that this extremely wide-orbit binary could have evolved from a triple system that underwent an asymmetric supernova explosion, though find that significant fine-tuning during the explosion is required. Finally, we discuss the implications of the long period orbit on the timing stability of PSR J1024-0719 in light of its inclusion in pulsar timing arrays.

  12. Advanced Life Systems for Extreme Environments: An Arctic Application

    NASA Technical Reports Server (NTRS)

    Lewis, Carol E.; Stanford, Kerry L.; Bubenheim, David L.; Covington, Alan (Technical Monitor)

    1995-01-01

    The problems of obtaining adequate pure drinking water and disposing of liquid and solid waste in the U.S. Arctic, a region where virtually all water is frozen solid for much of the year, has led to unsanitary solutions (U.S. Arctic Research Commission). These solutions are also damaging to the environment. Sanitation and a safe water supply are particularly problems in rural villages. About one-fourth of Alaska's 86.000 Native residents live in these communities. They are without running water and use plastic buckets for toilets. The outbreak of diseases is believed to be partially attributable to exposure to human waste. Villages with the most frequent outbreaks of disease are those in which running water is difficult to obtain (Office of Technology Assessment, 1994). Waste is emptied into open lagoons, rivers, or onto the sea coast. It does not degrade rapidly and in addition to affecting human health, can be harmful to the fragile ecology of the Arctic and the indigenous wildlife and fish populations. Advanced Life Systems for Extreme Environments (ALSEE) provides a solution to sanitation and safe water problems. The system uses an advanced integrated technology developed for Antarctic and space applications. ALSEE uses the systems approach to address more than waste and water problems. By incorporating hydroponic horticulture and aquaculture into the waste treatment system, ALSEE addresses the quality and quantity of fresh foods available to Arctic residents. A temperate climate is required for year-round plant growth. ALSEE facilities can be designed to include a climate controlled area within the structure. This type of environment is a change from the long periods of darkness and cold found in the Arctic and can help alleviate stress so often associated with these extremes. While the overall concept of ALSEE projects is advanced, system facilities can be operated by village residents with appropriate training. ALSEE provides continuing training and

  13. Mechanism for stickiness suppression during extreme events in Hamiltonian systems.

    PubMed

    Krüger, Taline Suellen; Galuzio, Paulo Paneque; Prado, Thiago de Lima; Viana, Ricardo Luiz; Szezech, José Danilo; Lopes, Sergio Roberto

    2015-06-01

    In this paper we study how hyperbolic and nonhyperbolic regions in the neighborhood of a resonant island perform an important role allowing or forbidding stickiness phenomenon around islands in conservative systems. The vicinity of the island is composed of nonhyperbolic areas that almost prevent the trajectory to visit the island edge. For some specific parameters tiny channels are embedded in the nonhyperbolic area that are associated to hyperbolic fixed points localized in the neighborhood of the islands. Such channels allow the trajectory to be injected in the inner portion of the vicinity. When the trajectory crosses the barrier imposed by the nonhyperbolic regions, it spends a long time abandoning the vicinity of the island, since the barrier also prevents the trajectory from escaping from the neighborhood of the island. In this scenario the nonhyperbolic structures are responsible for the stickiness phenomena and, more than that, the strength of the sticky effect. We show that those properties of the phase space allow us to manipulate the existence of extreme events (and the transport associated to it) responsible for the nonequilibrium fluctuation of the system. In fact we demonstrate that by monitoring very small portions of the phase space (namely, ≈1×10(-5)% of it) it is possible to generate a completely diffusive system eliminating long-time recurrences that result from the stickiness phenomenon. PMID:26172768

  14. Mechanism for stickiness suppression during extreme events in Hamiltonian systems

    NASA Astrophysics Data System (ADS)

    Krüger, Taline Suellen; Galuzio, Paulo Paneque; Prado, Thiago de Lima; Viana, Ricardo Luiz; Szezech, José Danilo; Lopes, Sergio Roberto

    2015-06-01

    In this paper we study how hyperbolic and nonhyperbolic regions in the neighborhood of a resonant island perform an important role allowing or forbidding stickiness phenomenon around islands in conservative systems. The vicinity of the island is composed of nonhyperbolic areas that almost prevent the trajectory to visit the island edge. For some specific parameters tiny channels are embedded in the nonhyperbolic area that are associated to hyperbolic fixed points localized in the neighborhood of the islands. Such channels allow the trajectory to be injected in the inner portion of the vicinity. When the trajectory crosses the barrier imposed by the nonhyperbolic regions, it spends a long time abandoning the vicinity of the island, since the barrier also prevents the trajectory from escaping from the neighborhood of the island. In this scenario the nonhyperbolic structures are responsible for the stickiness phenomena and, more than that, the strength of the sticky effect. We show that those properties of the phase space allow us to manipulate the existence of extreme events (and the transport associated to it) responsible for the nonequilibrium fluctuation of the system. In fact we demonstrate that by monitoring very small portions of the phase space (namely, ≈1 ×10-5% of it) it is possible to generate a completely diffusive system eliminating long-time recurrences that result from the stickiness phenomenon.

  15. Water Detected in the Terrestrial Zone of Extreme Solar Systems

    NASA Astrophysics Data System (ADS)

    Farihi, Jay

    2015-12-01

    Life as we know it requires water in contact with a rocky planetary surface. In the Solar System, water and other volatiles must have been delivered to a dry Earth from planetesimals, where asteroids in the outer main belt and Jupiter-Saturn region are excellent candidates. The first extrasolar analog of these rocky and water-rich planetesimals was reported between ESS II and III (Farihi et al. 2013, Science, 342, 218), and there is now evidence for additional examples. These results imply an underlying population of large, extrasolar planetesimals formed near a snow line, and suggesting a common mechanism for water delivery to habitable exoplanets.I will present Hubble, Spitzer, and ground-based data that demonstrate the confirmed and likely water-rich nature of exo-asteroids identified in a growing number of white dwarf planetary systems. These extreme solar systems formed and evolved around A-type (and similar) stars -- now firmly retired -- and the asteroid debris now orbits and pollutes the white dwarf with heavy elements, including oxygen in excess of that expected for oxide minerals. The abundance patterns are also carbon-poor, indicating the parent bodies were not icy planetesimals analogous to comets, but instead similar in overall composition to asteroids in the outer main belt.Importantly, these remnant exoplanetary systems imply architectures similar to the Solar System, where a giant planet exterior to a snow line perturbs rocky asteroids on the interior. Thus, they appear to share basic characteristics with HR 8799, Vega, Fomalhaut, and epsilon Eridani where two disks of debris are separated by giant planet(s), with one belt near the snow line. If such archictectures are as common as implied by polluted white dwarfs, then at least 30% of 1.2-3.0 Msun stars have both the tools and ingredentients for water delivery in their terrestrial planet zones.

  16. An operations and command systems for the extreme ultraviolet explorer

    NASA Technical Reports Server (NTRS)

    Muscettola, Nicola; Korsmeyer, David J.; Olson, Eric C.; Wong, Gary

    1994-01-01

    About 40% of the budget of a scientific spacecraft mission is usually consumed by Mission Operations & Data Analysis (MO&DA) with MO driving these costs. In the current practice, MO is separated from spacecraft design and comes in focus relatively late in the mission life cycle. As a result, spacecraft may be designed that are very difficult to operate. NASA centers have extensive MO expertise but often lessons learned in one mission are not exploited for other parallel or future missions. A significant reduction of MO costs is essential to ensure a continuing and growing access to space for the scientific community. We are addressing some of these issues with a highly automated payload operations and command system for an existing mission, the Extreme Ultraviolet Explorer (EUVE). EUVE is currently operated jointly by the Goddard Space Flight Center (GSFC), responsible for spacecraft operations, and the Center for Extreme Ultraviolet Astrophysics (CEA) of the University of California, Berkeley, which controls the telescopes and scientific instruments aboard the satellite. The new automated system is being developed by a team including personnel from the NASA Ames Research Center (ARC), the Jet Propulsion Laboratory (JPL) and the Center for EUV Astrophysics (CEA). An important goal of the project is to provide AI-based technology that can be easily operated by nonspecialists in AI. Another important goal is the reusability of the techniques for other missions. Models of the EUVE spacecraft need to be built both for planning/scheduling and for monitoring. In both cases, our modeling tools allow the assembly of a spacecraft model from separate sub-models of the various spacecraft subsystems. These sub-models are reusable; therefore, building mission operations systems for another small satellite mission will require choosing pre-existing modules, reparametrizing them with respect to the actual satellite telemetry information, and reassembling them in a new model. We

  17. Electro-Mechanical Systems for Extreme Space Environments

    NASA Technical Reports Server (NTRS)

    Mojarradi, Mohammad M.; Tyler, Tony R.; Abel, Phillip B.; Levanas, Greg

    2011-01-01

    Exploration beyond low earth orbit presents challenges for hardware that must operate in extreme environments. The current state of the art is to isolate and provide heating for sensitive hardware in order to survive. However, this protection results in penalties of weight and power for the spacecraft. This is particularly true for electro-mechanical based technology such as electronics, actuators and sensors. Especially when considering distributed electronics, many electro-mechanical systems need to be located in appendage type locations, making it much harder to protect from the extreme environments. The purpose of this paper to describe the advances made in the area of developing electro-mechanical technology to survive these environments with minimal protection. The Jet Propulsion Lab (JPL), the Glenn Research Center (GRC), the Langley Research Center (LaRC), and Aeroflex, Inc. over the last few years have worked to develop and test electro-mechanical hardware that will meet the stringent environmental demands of the moon, and which can also be leveraged for other challenging space exploration missions. Prototype actuators and electronics have been built and tested. Brushless DC actuators designed by Aeroflex, Inc have been tested with interface temperatures as low as 14 degrees Kelvin. Testing of the Aeroflex design has shown that a brushless DC motor with a single stage planetary gearbox can operate in low temperature environments for at least 120 million cycles (measured at motor) if long life is considered as part of the design. A motor control distributed electronics concept developed by JPL was built and operated at temperatures as low as -160 C, with many components still operational down to -245 C. Testing identified the components not capable of meeting the low temperature goal of -230 C. This distributed controller is universal in design with the ability to control different types of motors and read many different types of sensors. The controller

  18. Spectral theory of extreme statistics in birth-death systems

    NASA Astrophysics Data System (ADS)

    Meerson, Baruch

    2008-03-01

    Statistics of rare events, or large deviations, in chemical reactions and systems of birth-death type have attracted a great deal of interest in many areas of science including cell biochemistry, astrochemistry, epidemiology, population biology, etc. Large deviations become of vital importance when discrete (non-continuum) nature of a population of ``particles'' (molecules, bacteria, cells, animals or even humans) and stochastic character of interactions can drive the population to extinction. I will briefly review the novel spectral method [1-3] for calculating the extreme statistics of a broad class of birth-death processes and reactions involving a single species. The spectral method combines the probability generating function formalism with the Sturm-Liouville theory of linear differential operators. It involves a controlled perturbative treatment based on a natural large parameter of the problem: the average number of particles/individuals in a stationary or metastable state. For extinction (the first passage) problems the method yields accurate results for the extinction statistics and for the quasi-stationary probability distribution, including the tails, of metastable states. I will demonstrate the power of the method on the example of a branching and annihilation reaction, A ->-2.8mm2mm2A,,A ->-2.8mm2mm , representative of a rather general class of processes. *M. Assaf and B. Meerson, Phys. Rev. Lett. 97, 200602 (2006). *M. Assaf and B. Meerson, Phys. Rev. E 74, 041115 (2006). *M. Assaf and B. Meerson, Phys. Rev. E 75, 031122 (2007).

  19. Extreme accumulation of nucleotides in simulated hydrothermal pore systems

    PubMed Central

    Baaske, Philipp; Weinert, Franz M.; Duhr, Stefan; Lemke, Kono H.; Russell, Michael J.; Braun, Dieter

    2007-01-01

    We simulate molecular transport in elongated hydrothermal pore systems influenced by a thermal gradient. We find extreme accumulation of molecules in a wide variety of plugged pores. The mechanism is able to provide highly concentrated single nucleotides, suitable for operations of an RNA world at the origin of life. It is driven solely by the thermal gradient across a pore. On the one hand, the fluid is shuttled by thermal convection along the pore, whereas on the other hand, the molecules drift across the pore, driven by thermodiffusion. As a result, millimeter-sized pores accumulate even single nucleotides more than 108-fold into micrometer-sized regions. The enhanced concentration of molecules is found in the bulk water near the closed bottom end of the pore. Because the accumulation depends exponentially on the pore length and temperature difference, it is considerably robust with respect to changes in the cleft geometry and the molecular dimensions. Whereas thin pores can concentrate only long polynucleotides, thicker pores accumulate short and long polynucleotides equally well and allow various molecular compositions. This setting also provides a temperature oscillation, shown previously to exponentially replicate DNA in the protein-assisted PCR. Our results indicate that, for life to evolve, complicated active membrane transport is not required for the initial steps. We find that interlinked mineral pores in a thermal gradient provide a compelling high-concentration starting point for the molecular evolution of life. PMID:17494767

  20. Optical Design for Extremely Large Telescope Adaptive Optics Systems

    SciTech Connect

    Bauman, B J

    2003-11-26

    Designing an adaptive optics (AO) system for extremely large telescopes (ELT's) will present new optical engineering challenges. Several of these challenges are addressed in this work, including first-order design of multi-conjugate adaptive optics (MCAO) systems, pyramid wavefront sensors (PWFS's), and laser guide star (LGS) spot elongation. MCAO systems need to be designed in consideration of various constraints, including deformable mirror size and correction height. The y,{bar y} method of first-order optical design is a graphical technique that uses a plot with marginal and chief ray heights as coordinates; the optical system is represented as a segmented line. This method is shown to be a powerful tool in designing MCAO systems. From these analyses, important conclusions about configurations are derived. PWFS's, which offer an alternative to Shack-Hartmann (SH) wavefront sensors (WFS's), are envisioned as the workhorse of layer-oriented adaptive optics. Current approaches use a 4-faceted glass pyramid to create a WFS analogous to a quad-cell SH WFS. PWFS's and SH WFS's are compared and some newly-considered similarities and PWFS advantages are presented. Techniques to extend PWFS's are offered: First, PWFS's can be extended to more pixels in the image by tiling pyramids contiguously. Second, pyramids, which are difficult to manufacture, can be replaced by less expensive lenslet arrays. An approach is outlined to convert existing SH WFS's to PWFS's for easy evaluation of PWFS's. Also, a demonstration of PWFS's in sensing varying amounts of an aberration is presented. For ELT's, the finite altitude and finite thickness of LGS's means that the LGS will appear elongated from the viewpoint of subapertures not directly under the telescope. Two techniques for dealing with LGS spot elongation in SH WFS's are presented. One method assumes that the laser will be pulsed and uses a segmented micro-electromechanical system (MEMS) to track the LGS light subaperture by

  1. Direct dose confirmation of quantitative autoradiography with micro-TLD measurements for radioimmunotherapy

    SciTech Connect

    Griffith, M.H.; Yorke, E.D.; Wessels, B.W.; DeNardo, G.L.; Neacy, W.P.

    1988-11-01

    Autoradiography has shown marked heterogeneous distribution of radioactivity in all ten radiolabeled monoclonal antibody/tumor combinations evaluated by our laboratories for radioimmunotherapy (RIT) in mice. Quantitative autoradiography was performed on two of these combinations (131I-B72.3/colorectal carcinoma and 131I-LYM-1/Raji B-cell lymphoma) to obtain a correlation of film density with radiolabeled antibody distribution. Through the use of sectioned mini-thermoluminescent dosimeter(s) (TLD) or micro-TLD, isodose curves were generated from the film gradient density lines. A computer program was written to compare theoretical absorbed dose calculations to measured micro-TLD values. First-order agreement was reached for both antibody/tumor systems: (a) B72.3/colorectal system--810 cGy measured/824 cGy calculated per 200 microCi injected and (b) LYM-1/lymphoma system--1,740 cGy measured/1,580 cGy calculated per 656 microCi injected (1 cGy = 1 rad). Additionally, the measured absorbed dose heterogeneity over a 500-micron length of up to 400% which suggests that the use of quantitative autoradiography is necessary in order to correctly determine the underlying radiobiological effects of RIT. Theoretical computer modeling based on similar autoradiographic activity distributions has also provided a convenient means of assessing absorbed dose variation patterns from other radiolabels such as 90Y.

  2. Static binary systems of extreme charged black holes

    NASA Astrophysics Data System (ADS)

    Cabrera-Munguia, I.; Manko, V. S.; Ruiz, E.

    2010-12-01

    The extreme limit of the double-Reissner-Nordström spacetime results in two particular solutions. The first one is the Majumdar-Papapetrou solution which describes two charged non-rotating extreme black holes in neutral equilibrium, the individual charges being equal to the respective masses. The second one is identified as the Bonnor solution whose constituents cannot be in equilibrium and are separated by a strut, their charges having opposite signs and exceeding the respective masses in absolute value.

  3. THE COLORS OF EXTREME OUTER SOLAR SYSTEM OBJECTS

    SciTech Connect

    Sheppard, Scott S.

    2010-04-15

    Extreme outer solar system objects have possible origins beyond the Kuiper Belt edge, high inclinations, very large semimajor axes, or large perihelion distances. Thirty-three such objects were observed in this work to determine their optical colors. All three objects that have been dynamically linked to the inner Oort Cloud by various authors ((90377) Sedna, 2006 SQ{sub 372}, and (87269) 2000 OO{sub 67}) were found to have ultra-red surface material (spectral gradient, S {approx} 25). Ultra-red material is generally associated with rich organics and the low inclination 'cold' classical Kuiper Belt objects (KBOs). The observations detailed here show that very red material may be a more general feature for objects kept far from the Sun. The recently discovered retrograde outer solar system objects (2008 KV{sub 42} and 2008 YB{sub 3}) and the high inclination object (127546) 2002 XU{sub 93} show only moderately red surfaces (S {approx} 9) very similar to known comets, suspected dead comets, Jupiter and Neptune Trojans, irregular satellites, D-type asteroids, and damocloids. The extended or detached disk objects, which have large perihelion distances and are thus considered to be detached from the influence of the giant planets but yet have large eccentricities, are found to have mostly moderately red colors (10 {approx}< S {approx}< 18). The colors of the detached disk objects, including the dynamically unusual 2004 XR{sub 190} and (148209) 2000 CR{sub 105}, are similar to the scattered disk and Plutino populations. Thus the detached disk, scattered disk, Plutino, and high inclination 'hot' classical objects likely have a similar mix of objects from the same source regions. Outer classical KBOs, including (48639) 1995 TL{sub 8}, were found to have very red surfaces (18 {approx}< S {approx}< 30). The low inclination 'cold' classical KBOs, outer classical KBOs and possibly the inner Oort Cloud appear to be dominated by ultra-red objects (S {approx}> 25) and thus do not

  4. Radical loss of an extreme extra-pair mating system

    PubMed Central

    Kingma, Sjouke A; Hall, Michelle L; Segelbacher, Gernot; Peters, Anne

    2009-01-01

    Background Mating outside the pair-bond is surprisingly common in socially monogamous birds, but rates of extra-pair paternity (EPP) vary widely between species. Although differences in life-history and contemporary ecological factors may explain some interspecific variation, evolutionary forces driving extra-pair (EP) mating remain largely obscure. Also, since there is a large phylogenetic component to the frequency of EPP, evolutionary inertia may contribute substantially to observed EP mating patterns. However, the relative importance of plasticity and phylogenetic constraints on the incidence of EP mating remains largely unknown. Results We here demonstrate very low levels of EPP (4.4% of offspring) in the purple-crowned fairy-wren Malurus coronatus, a member of the genus with the highest known levels of EPP in birds. In addition, we show absence of the suite of distinctive behavioral and morphological adaptations associated with EP mating that characterize other fairy-wrens. Phylogenetic parsimony implies that these characteristics were lost in one speciation event. Nonetheless, many life-history and breeding parameters that are hypothesized to drive interspecific variation in EPP are not different in the purple-crowned fairy-wren compared to its promiscuous congeners. Conclusion Such radical loss of an extreme EP mating system with all associated adaptations from a lineage of biologically very similar species indicates that evolutionary inertia does not necessarily constrain interspecific variation in EPP. Moreover, if apparently minor interspecific differences regularly cause large differences in EPP, this may be one reason why the evolution of EP mating is still poorly understood. PMID:19454026

  5. On extremal quantum states of composite systems with fixed marginals

    NASA Astrophysics Data System (ADS)

    Rudolph, Oliver

    2004-11-01

    We study the convex set C(ρ1,ρ2) of all bipartite quantum states with fixed marginal states ρ1 and ρ2. The extremal states in this set have recently been characterized by Parthasarathy [Ann. Henri Poincaré (to appear), quant-ph/0307182]. Here we present an alternative necessary and sufficient condition for a state in C(ρ1,ρ2) to be extremal. Our approach is based on a canonical duality between bipartite states and a certain class of completely positive maps and has the advantage that it is easier to check and to construct explicit examples of extremal states. In dimension 2×2 we give a simple new proof for the fact that all extremal states in C(1/21,1/21) are precisely the projectors onto maximally entangled wave functions. We also prove that in higher dimension this does not hold and construct an explicit example of an extremal state in C(1/31,1/31) that is not maximally entangled. Generalizations of this result to higher dimensions are also discussed.

  6. Sungrazing comets: Probing the inner extremes of the Solar System

    NASA Astrophysics Data System (ADS)

    Knight, M.

    2014-07-01

    /Machholz 1. The third group, Meyer, has not been linked to any known solar system object and has an unknown orbital period. The remaining known sungrazing comets have a variety of orbits and, with the notable exception of ISON, are generally not observed extensively. Due to their extreme orbits, sungrazing comets offer unique opportunities for understanding evolutionary processes in our solar system. During their perihelion passages they experience equilibrium temperatures exceeding 1500 K, resulting in sublimation of their dust and potentially allowing the least volatile components of our solar system to be cataloged. In fact, while all of the near-Sun objects discovered by SOHO and STEREO are designated ''comets'', many of those not associated with other known cometary objects may be asteroids or defunct comets whose apparent activity at these distances is due to sublimation of their bare surfaces. Sungrazing comets also experience strong tidal forces, resulting in frequent fragmentation. Such breakups expose the unprocessed interiors, potentially allowing intercomparison of the compositions of discrete fragments and revealing the size distribution of the planetessimals out of which the parent comet formed. Finally, it has recently become possible to use comets as ''solar probes'', treating them as test particles that can reveal properties of the solar environment such as the coronal temperature and density, magnetic field strength, and solar wind speed and direction.

  7. Dedicated Cone-Beam CT System for Extremity Imaging

    PubMed Central

    Al Muhit, Abdullah; Zbijewski, Wojciech; Thawait, Gaurav K.; Stayman, J. Webster; Packard, Nathan; Senn, Robert; Yang, Dong; Foos, David H.; Yorkston, John; Siewerdsen, Jeffrey H.

    2014-01-01

    Purpose To provide initial assessment of image quality and dose for a cone-beam computed tomographic (CT) scanner dedicated to extremity imaging. Materials and Methods A prototype cone-beam CT scanner has been developed for imaging the extremities, including the weight-bearing lower extremities. Initial technical assessment included evaluation of radiation dose measured as a function of kilovolt peak and tube output (in milliampere seconds), contrast resolution assessed in terms of the signal difference–to-noise ratio (SDNR), spatial resolution semiquantitatively assessed by using a line-pair module from a phantom, and qualitative evaluation of cadaver images for potential diagnostic value and image artifacts by an expert CT observer (musculoskeletal radiologist). Results The dose for a nominal scan protocol (80 kVp, 108 mAs) was 9 mGy (absolute dose measured at the center of a CT dose index phantom). SDNR was maximized with the 80-kVp scan technique, and contrast resolution was sufficient for visualization of muscle, fat, ligaments and/or tendons, cartilage joint space, and bone. Spatial resolution in the axial plane exceeded 15 line pairs per centimeter. Streaks associated with x-ray scatter (in thicker regions of the patient—eg, the knee), beam hardening (about cortical bone—eg, the femoral shaft), and cone-beam artifacts (at joint space surfaces oriented along the scanning plane—eg, the interphalangeal joints) presented a slight impediment to visualization. Cadaver images (elbow, hand, knee, and foot) demonstrated excellent visibility of bone detail and good soft-tissue visibility suitable to a broad spectrum of musculoskeletal indications. Conclusion A dedicated extremity cone-beam CT scanner capable of imaging upper and lower extremities (including weight-bearing examinations) provides sufficient image quality and favorable dose characteristics to warrant further evaluation for clinical use. © RSNA, 2013 Online supplemental material is available for

  8. A data logger for personnel monitoring TLD readers

    NASA Astrophysics Data System (ADS)

    Kulkarni, M. S.; Ratna, P.; Kannan, S.; Venkateswaran, T. V.

    1993-10-01

    A data logger for the manual type BARC TLD reader has been developed for connecting the TLD reader to an IBM PC/XT for a direct transfer of data, evaluation and preparation of radiation dose reports. The microprocessor controlled data logger has features like low or high resolution glow curve storage, storage of dosimetric data along with the identification numbers of about 300 dosimeters, RS-232 serial interface for connection to a PC and a built-in hand shake software to facilitate connection of two or more data loggers to a PC. The data loggers are in use with TLD readers for personnel monitoring in a number of centres in India. The hardware and software details of the data logger are discussed.

  9. Performance of Harshaw TLD-100H two-element Dosemeter.

    PubMed

    Luo, L Z; Rotunda, J E

    2006-01-01

    One of the advantages of LiF based thermoluminescent (TL) materials is its tissue-equivalent property. The Harshaw TLD-100H (LiF:Mg,Cu,P) material has demonstrated that it has a near-flat photon energy response and high sensitivity. With the optimized dosemeter filters built into the holder, the Harshaw TLD-100H two-element dosemeter can be used as a whole body personnel dosemeter for gamma, X ray and beta monitoring without the use of an algorithm or correction factor. This paper presents the dose performance of the Harshaw TLD-100H two-element dosemeter against the ANSI N13.11-2001 standard and the results of tests that are required in IEC 1066 International Standard. PMID:16644944

  10. TLD-100 and Radiochromic Dye Film in Medical Dosimetry

    SciTech Connect

    Mercado-Uribe, H.

    2006-01-06

    TLD-100 and radiochromic dye films are two types of the dosimeters most used in the medical physics area. Both are secondary detectors and operate in a different way and in different dose measurement ranges. The use of TLD-100 is based on the thermoluminescent process, and the RDF in the optical density change when has been exposed to an irradiation field previously. In this work it is analyzed in a general way, the advantages and characteristics of these detectors and the reasons of the great increase in their use in the last decades.

  11. Pilot system on extreme climate monitoring and early warning for long range forecast in Korea

    NASA Astrophysics Data System (ADS)

    Cho, K.; Park, B. K.; E-hyung, P.; Gong, Y.; Kim, H. K.; Park, S.; Min, S. K.; Yoo, H. D.

    2015-12-01

    Recently, extreme weather/climate events such as heat waves, flooding/droughts etc. have been increasing in frequency and intensity under climate change over the world. Also, they can have substantial impacts on ecosystem and human society (agriculture, health, and economy) of the affected regions. According to future projections of climate, extreme weather and climate events in Korea are expected to occure more frequently with stronger intensity over the 21st century. For the better long range forecast, it is also fundamentally ruquired to develop a supporting system in terms of extreme weather and climate events including forequency and trend. In this context, the KMA (Korea Meteorological Administration) has recently initiated a development of the extreme climate monintoring and early warning system for long range forecast, which consists of three sub-system components; (1) Real-time climate monitoring system, (2) Ensemble prediction system, and (3) Mechanism analysis and display system for climate extremes. As a first step, a pilot system has been designed focusing on temperature extremes such heat waves and cold snaps using daily, monthly and seasonal observations and model prediction output on the global, regional and national levels. In parallel, the skills of the KMA long range prediction system are being evaluated comprehensively for weather and climate extremes, for which varous case studies are conducted to better understand the observed variations of extrem climates and responsible mechanisms and also to assess predictability of the ensemble prediction system for extremes. Details in the KMA extreme climate monitoring and early warning system will be intorduced and some preliminary results will be discussed for heat/cold waves in Korea.

  12. Calculation of the TLD700:LiF energy response from Ir-192 using novel Monte Carlo and empirical methods.

    PubMed

    Rijken, J D; Harris-Phillips, W; Lawson, J M

    2015-03-01

    Lithium fluoride thermoluminescent dosimeters (TLDs) exhibit a dependence on the energy of the radiation beam of interest so need to be carefully calibrated for different energy spectra if used for clinical radiation oncology beam dosimetry and quality assurance. TLD energy response was investigated for a specific set of TLD700:LiF(Mg,Ti) chips for a high dose rate (192)Ir brachytherapy source. A novel method of energy response calculation for (192)Ir was developed where dose was determined through Monte Carlo modelling in Geant4. The TLD response was then measured experimentally. Results showed that TLD700 has a depth dependent response in water ranging from 1.170 ± 0.125 at 20 mm to 0.976 ± 0.043 at 50 mm (normalised to a nominal 6 MV beam response). The method of calibration and Monte Carlo data developed through this study could be easily applied by other Medical Physics departments seeking to use TLDs for (192)Ir patient dosimetry or treatment planning system experimental verification. PMID:25663432

  13. Data-driven prediction and prevention of extreme events in a spatially extended excitable system

    NASA Astrophysics Data System (ADS)

    Bialonski, Stephan; Ansmann, Gerrit; Kantz, Holger

    2015-10-01

    Extreme events occur in many spatially extended dynamical systems, often devastatingly affecting human life, which makes their reliable prediction and efficient prevention highly desirable. We study the prediction and prevention of extreme events in a spatially extended system, a system of coupled FitzHugh-Nagumo units, in which extreme events occur in a spatially and temporally irregular way. Mimicking typical constraints faced in field studies, we assume not to know the governing equations of motion and to be able to observe only a subset of all phase-space variables for a limited period of time. Based on reconstructing the local dynamics from data and despite being challenged by the rareness of events, we are able to predict extreme events remarkably well. With small, rare, and spatiotemporally localized perturbations which are guided by our predictions, we are able to completely suppress extreme events in this system.

  14. Problems associated with large scale personnel monitoring of photons using lithium-fluoride TLD-100

    SciTech Connect

    Not Available

    1985-01-01

    The dosimetric properties of a large batch of lithium fluoride TLD-100 dosimeters when exposed to photons for total absorbed doses in the region from 0.1-10 mGy (10-100 mr) have been examined in this work. This region is of particular importance because in many operational health physics situations the majority (>90%) of all recorded absorbed doses to personnel lie in this region. With the possibility that occupational radiation dose limits may be reduced in the future accurate monitoring of individuals in this region will be of prime importance. The purpose of this thesis was to point out several effects which could compromise accurate dosimetric measurements in this region and to suggest some methods to minimize them. These effects include the effect of TLD batch composition, overresponse of the dosimeter to low energy photons, dose rate effects, the effects of storing the dosimeter before readout, and possible interference from ultraviolet and radiofrequency radiation. Each of these items can cause errors which can range up to 70%, depending on the total absorbed dose and the particulars of the radiation exposure. One effect which is of extreme interest is the induction of a thermoluminescent signal by radiofrequency radiation. Although this effect can cause gross errors in estimating the ionizing dose, it opens the possibility that LiF or another phosphor may have an application as a non-ionizing radiation dosimeter.

  15. Systemic inflammation and cerebral palsy risk in extremely preterm infants

    PubMed Central

    Kuban, KCK; O’Shea, TM; Allred, EN; Paneth, N; Hirtz, D; Fichorova, RN; Leviton, A

    2013-01-01

    We hypothesized that among extremely preterm infants, elevated concentrations of inflammation-related proteins in neonatal blood are associated with cerebral palsy (CP) at 24 months. Methods In 939 infants born before 28 weeks gestation, we measured blood concentrations of 25 proteins on postnatal days 1, 7, and 14 and evaluated associations between elevated protein concentrations and CP diagnosis. Results Protein elevations within three days of birth were not associated with CP. Elevations of TNF-α, TNF-R1, IL-8, ICAM-1, on at least two days were associated with diparesis. Recurrent-persistent elevations of IL-6, E-SEL, or IGFBP-1 were associated with hemiparesis. Diparesis and hemiparesis were more likely among infants who had at least four of nine proteins elevations that previously have been associated with cognitive impairment and microcephaly. Interpretation Repeated elevations of inflammation-related proteins during the first two postnatal weeks are associated with increased risk of CP. PMID:24646503

  16. OSLD energy response performance and dose accuracy at 24 - 1250 keV: Comparison with TLD-100H and TLD-100

    SciTech Connect

    Kadir, A. B. A.; Priharti, W.; Samat, S. B.; Dolah, M. T.

    2013-11-27

    OSLD was evaluated in terms of energy response and accuracy of the measured dose in comparison with TLD-100H and TLD-100. The OSLD showed a better energy response performance for H{sub p}(10) whereas for H{sub p}(0.07), TLD-100H is superior than the others. The OSLD dose accuracy is comparable with the other two dosimeters since it fulfilled the requirement of the ICRP trumpet graph analysis.

  17. At-wavelength, system-level flare characterization of extreme-ultraviolet optical systems.

    PubMed

    Naulleau, P; Goldberg, K A; Gullikson, E M; Bokor, J

    2000-06-10

    The extreme-ultraviolet (EUV) phase-shifting point-diffraction interferometer (PS/PDI) has recently been developed to provide high-accuracy wave-front characterization critical to the development of EUV lithography systems. Here we describe an enhanced implementation of the PS/PDI that significantly extends its measurement bandwidth. The enhanced PS/PDI is capable of simultaneously characterizing both wave front and flare. PS/PDI-based flare characterization of two recently fabricated EUV 10x-reduction lithographic optical systems is presented. PMID:18345220

  18. Extreme Cost Reductions with Multi-Megawatt Centralized Inverter Systems

    SciTech Connect

    Schwabe, Ulrich; Fishman, Oleg

    2015-03-20

    The objective of this project was to fully develop, demonstrate, and commercialize a new type of utility scale PV system. Based on patented technology, this includes the development of a truly centralized inverter system with capacities up to 100MW, and a high voltage, distributed harvesting approach. This system promises to greatly impact both the energy yield from large scale PV systems by reducing losses and increasing yield from mismatched arrays, as well as reduce overall system costs through very cost effective conversion and BOS cost reductions enabled by higher voltage operation.

  19. Error Analysis of non-TLD HDR Brachytherapy Dosimetric Techniques

    NASA Astrophysics Data System (ADS)

    Amoush, Ahmad

    The American Association of Physicists in Medicine Task Group Report43 (AAPM-TG43) and its updated version TG-43U1 rely on the LiF TLD detector to determine the experimental absolute dose rate for brachytherapy. The recommended uncertainty estimates associated with TLD experimental dosimetry include 5% for statistical errors (Type A) and 7% for systematic errors (Type B). TG-43U1 protocol does not include recommendation for other experimental dosimetric techniques to calculate the absolute dose for brachytherapy. This research used two independent experimental methods and Monte Carlo simulations to investigate and analyze uncertainties and errors associated with absolute dosimetry of HDR brachytherapy for a Tandem applicator. An A16 MicroChamber* and one dose MOSFET detectors† were selected to meet the TG-43U1 recommendations for experimental dosimetry. Statistical and systematic uncertainty analyses associated with each experimental technique were analyzed quantitatively using MCNPX 2.6‡ to evaluate source positional error, Tandem positional error, the source spectrum, phantom size effect, reproducibility, temperature and pressure effects, volume averaging, stem and wall effects, and Tandem effect. Absolute dose calculations for clinical use are based on Treatment Planning System (TPS) with no corrections for the above uncertainties. Absolute dose and uncertainties along the transverse plane were predicted for the A16 microchamber. The generated overall uncertainties are 22%, 17%, 15%, 15%, 16%, 17%, and 19% at 1cm, 2cm, 3cm, 4cm, and 5cm, respectively. Predicting the dose beyond 5cm is complicated due to low signal-to-noise ratio, cable effect, and stem effect for the A16 microchamber. Since dose beyond 5cm adds no clinical information, it has been ignored in this study. The absolute dose was predicted for the MOSFET detector from 1cm to 7cm along the transverse plane. The generated overall uncertainties are 23%, 11%, 8%, 7%, 7%, 9%, and 8% at 1cm, 2cm, 3cm

  20. Sensitivity calibration of an imaging extreme ultraviolet spectrometer-detector system for determining the efficiency of broadband extreme ultraviolet sources

    SciTech Connect

    Fuchs, S.; Roedel, C.; Bierbach, J.; Paz, A. E.; Foerster, E.; Paulus, G. G.; Krebs, M.; Haedrich, S.; Limpert, J.; Kuschel, S.; Wuensche, M.; Hilbert, V.; Zastrau, U.

    2013-02-15

    We report on the absolute sensitivity calibration of an extreme ultraviolet (XUV) spectrometer system that is frequently employed to study emission from short-pulse laser experiments. The XUV spectrometer, consisting of a toroidal mirror and a transmission grating, was characterized at a synchrotron source in respect of the ratio of the detected to the incident photon flux at photon energies ranging from 15.5 eV to 99 eV. The absolute calibration allows the determination of the XUV photon number emitted by laser-based XUV sources, e.g., high-harmonic generation from plasma surfaces or in gaseous media. We have demonstrated high-harmonic generation in gases and plasma surfaces providing 2.3 {mu}W and {mu}J per harmonic using the respective generation mechanisms.

  1. Construction of a composite thin-element TLD using an optical-heating method.

    PubMed

    Yamamoto, O; Yasuno, Y; Minamide, S; Hasegawa, S; Tsutsui, H; Takenaga, M; Yamashita, T

    1982-09-01

    A composite thermoluminescent dosimeter (TLD), composed of four, thin TL elements with a high-speed reader, has been developed by employing an optical-heating method. Each TL element, which is 15 mg/cm2 thick with a 3 mm dia., is prepared by applying Li2B4O7:Cu or CaSO4:Tm to a plastic substrate 14 mg/cm2 thick. Each element can be heated to 350 degree C within 0.8 sec. by IR radiation from a tungsten lamp. The characteristics of this TLD system include the following: (1) the detection limit of the Li2B4O7:Cu is 3 mR and the limit for CaSO4:Tm is 0.1 mR; (2) the energy-dependence curves are similar to the dose-equivalent curve, showing slight under-responses by 15% near 70 KeV for Li2B4O7:Cu and over-responses by 50% at high energies for CaSO4:Tm; (3) despite quick heating, the residual dose is as low as 0.1% of the last exposure signal; (4) responses are very stable for more than 1,000 cycles of repeated exposure readings; (5) no false signal could be detected, even in the cases of sweat or soil contamination; (6) the thin Li2B4O7;Cu element can be used for skin dose monitoring; and (7) the processing time of the automatic reader for the composite dosimeter is 3 hr/500 dosimeters. This TLD system can be applied to personnel dosimetry, gate monitoring and environmental monitoring. PMID:7174331

  2. Extreme AO Observations of Two Triple Asteroid Systems with SPHERE

    NASA Astrophysics Data System (ADS)

    Yang, B.; Wahhaj, Z.; Beauvalet, L.; Marchis, F.; Dumas, C.; Marsset, M.; Nielsen, E. L.; Vachier, F.

    2016-04-01

    We present the discovery of a new satellite of asteroid (130) Elektra—S/2014 (130) 1—in differential imaging and in integral field spectroscopy data over multiple epochs obtained with Spectro-Polarimetric High-contrast Exoplanet Research/Very Large Telescope. This new (second) moonlet of Elektra is about 2 km across, on an eccentric orbit, and about 500 km away from the primary. For a comparative study, we also observed another triple asteroid system, (93) Minerva. For both systems, component-resolved reflectance spectra of the satellites and primary were obtained simultaneously. No significant spectral difference was observed between the satellites and the primary for either triple system. We find that the moonlets in both systems are more likely to have been created by sub-disruptive impacts as opposed to having been captured.

  3. Woven Thermal Protection System (Woven TPS) for Extreme Entry Environments

    NASA Video Gallery

    The Woven Thermal Protection System (WTPS) project explores an innovative way to design, develop and manufacture a family of ablative TPS materials using weaving technology and testing them in the ...

  4. Physics Characterization of TLD-600 and TLD-700 and Acceptance Testing of New XRAD 160 Biological X-Ray Irradiator

    NASA Astrophysics Data System (ADS)

    Cao, Yanan

    Project 1: Physics characterization of TLD-600 and TLD-700. Purpose: It is suggested that a pair of TLD-600 and TLD-700 can measure the exposure in neutron-photon mix fields. But the basic information of physics characterization of TLD-600 and 700 are not available. The purpose of this study was study the individual TLD variation and the energy dependence of TLD-600 and TLD-700. Methods: The individual calibration factors for 52 TLD-600 chips and 51 TLD-700 chips were determined under x-ray beams of 60 kVp, 80 kVp, 120 kVp, a mono-energetic 662 keV gamma beam of a Cs-137 source, and an Am-Be neutron beam (4.4 MeV). The individual calibration factor was calculated as the ratio of the group average response in uC/mR and the individual response in uC/mR. In addition, energy corrections factors for the individual calibration factors were determined, from each of the x-ray beams (60 kVp, 80 kVp, 120 kVp) to the 662 keV Cs-137 gamma beams. Results: For TLD-600, the range and relative standard deviation of the individual calibration factors are: 60 kVp (0.94003-1.0927, 3.5369%), 80 kVp (0.9395-1.0867, 3.0952%), 120 kVp (0.83403-1.0796, 4.5732%), 662 keV (0.80465-1.1926, 9.2515% ), AmBe (0.91740-0.94905, 3.0882% ); and the energy corrections factors relative to the 662 keV Cs-137 beams are: 60 kVp (1.2223), 80 kVp (1.1013), 120 kVp (1.0299). For TLD-700 the range and relative standard deviation of the individual calibration factors are: 60 kVp (0.94351-1.0630, 2.6044%), 80 kVp (0.91690-1.0614, 2.6996%), 120 kVp (0.95697-1.0474, 2.3606%), 662 keV (0.91348-1.2270, 4.2243%), AmBe (0.79330-1.2268, 9.1577%); and the energy corrections factors relative to the 662 keV Cs-137 beams are: 60 kVp (1.0373), 80 kVp (0.97661), 120 kVp (0.88532). Conclusion: We have measured individual calibration factors and the average energy correction factors for photon beams and Am-Be neutron beams. Our results will be used in the future experiments and measurements with TLD-600 and TLD-700. Project

  5. Scalable PGAS Metadata Management on Extreme Scale Systems

    SciTech Connect

    Chavarría-Miranda, Daniel; Agarwal, Khushbu; Straatsma, TP

    2013-05-16

    Programming models intended to run on exascale systems have a number of challenges to overcome, specially the sheer size of the system as measured by the number of concurrent software entities created and managed by the underlying runtime. It is clear from the size of these systems that any state maintained by the programming model has to be strictly sub-linear in size, in order not to overwhelm memory usage with pure overhead. A principal feature of Partitioned Global Address Space (PGAS) models is providing easy access to global-view distributed data structures. In order to provide efficient access to these distributed data structures, PGAS models must keep track of metadata such as where array sections are located with respect to processes/threads running on the HPC system. As PGAS models and applications become ubiquitous on very large transpetascale systems, a key component to their performance and scalability will be efficient and judicious use of memory for model overhead (metadata) compared to application data. We present an evaluation of several strategies to manage PGAS metadata that exhibit different space/time tradeoffs. We use two real-world PGAS applications to capture metadata usage patterns and gain insight into their communication behavior.

  6. EHF (Extremely High Frequency) telecommunications system engineering model

    NASA Astrophysics Data System (ADS)

    Allen, K. C.

    1986-04-01

    An EHF Telecommunication System Engineering Model (ETSEM) has been developed as an aid in the design of line-of-sight (LOS) communication systems from 10 to 100 GHz. ETSEM provides tabulation of path geometry parameters and analyzes ray-path and Fresnel zone clearances to help the engineer design the path. ETSEM also predicts the performance (availability) of both digital and analog systems based on state-of-the-art EHF propagation models and equipment specifications. Attenuation by rain, clear-air absorption, and multipath are modeled. These are expected to essentially determine the statistics of link availability as limited by propagation impairments. Performance may be predicted for any interval of months of the year. A climatological data base for North America and Europe provides parameters for the propagation models. ETSEM has been implemented on a desk-top computer. Weaknesses and limitations of the model are discussed and improvements are suggested.

  7. Novel Hydrogen Production Systems Operative at Thermodynamic Extremes

    SciTech Connect

    Gunsalus, Robert

    2012-11-30

    We have employed a suite of molecular, bioinformatics, and biochemical tools to interrogate the thermodynamically limiting steps of H{sub 2} production from fatty acids in syntrophic communities. We also developed a new microbial model system that generates high H{sub 2} concentrations (over 17% of the gas phase) with high H{sub 2} yields of over 3 moles H{sub 2} per mole glucose. Lastly, a systems-based study of biohydrogen production in model anaerobic consortia was performed to begin identifying key regulated steps as a precursor to modeling co-metabolism. The results of these studies significantly expand our ability to predict and model systems for H{sub 2} production in novel anaerobes that are currently very poorly documented or understood.

  8. An MHD generator energy flow time rate extremal controlling system

    SciTech Connect

    Vasiliev, V.V.

    1993-12-31

    The progress in the development and studying of new methods of producing electric energy, based on direct conversion of heat energy, raises the problem of more effective use of their power characteristics. Disclosure is made of a self-optimizing control system for an object with a unimodal quality function. The system comprises an object, a divider, a band-pass filter, an averaging filter, a multiplier, a final control element, an adder and further includes a search signal generator. The fashion and the system are presented in the USSR No. 684510, in the USA No. 4179730, in France No. 2386854, In Germany No. 2814963, in Japan No. 1369882. The progress in the development and studying of new method of producing electric energy, based on direct conversion of heat in MHD generator into electric energy, raises the problem of more effective use of their power characteristics.

  9. Microwave tomography of extremities: 1. Dedicated 2D system and physiological signatures.

    PubMed

    Semenov, Serguei; Kellam, James; Sizov, Yuri; Nazarov, Alexei; Williams, Thomas; Nair, Bindu; Pavlovsky, Andrey; Posukh, Vitaly; Quinn, Michael

    2011-04-01

    Microwave tomography (MWT) is a novel imaging modality which might be applicable for non-invasive assessment of functional and pathological conditions of biological tissues. Imaging of the soft tissue of extremities is one of its potential applications. The feasibility of this technology for such applications was demonstrated earlier. This is the first of two companion papers focused on an application of MWT for imaging of the extremity's soft tissues. The goal of this study is to assess the technical performance of the developed 2D MWT system dedicated for imaging of functional and pathological conditions of the extremity's soft tissues. Specifically, the system's performance was tested by its ability to detect signals associated with physiological activity and soft tissue interventions (circulatory related changes, blood flow reduction and a simulated compartmental syndrome)--the so-called physiological signatures. The developed 2D MWT system dedicated to the imaging of animal extremities demonstrates good technical performance allowing for stable and predictable data acquisition with reasonable agreement between the experimentally measured electromagnetic (EM) field and the simulated EM field within a measurement domain. Using the system, we were able to obtain physiological signatures associated with systolic versus diastolic phases of circulation in an animal extremity, reperfusion versus occlusion phases of the blood supply to the animal's extremity and a compartment syndrome. The imaging results are presented and discussed in the second companion paper. PMID:21364265

  10. Microwave tomography of extremities: 1. Dedicated 2D system and physiological signatures

    NASA Astrophysics Data System (ADS)

    Semenov, Serguei; Kellam, James; Sizov, Yuri; Nazarov, Alexei; Williams, Thomas; Nair, Bindu; Pavlovsky, Andrey; Posukh, Vitaly; Quinn, Michael

    2011-04-01

    Microwave tomography (MWT) is a novel imaging modality which might be applicable for non-invasive assessment of functional and pathological conditions of biological tissues. Imaging of the soft tissue of extremities is one of its potential applications. The feasibility of this technology for such applications was demonstrated earlier. This is the first of two companion papers focused on an application of MWT for imaging of the extremity's soft tissues. The goal of this study is to assess the technical performance of the developed 2D MWT system dedicated for imaging of functional and pathological conditions of the extremity's soft tissues. Specifically, the system's performance was tested by its ability to detect signals associated with physiological activity and soft tissue interventions (circulatory related changes, blood flow reduction and a simulated compartmental syndrome)—the so-called physiological signatures. The developed 2D MWT system dedicated to the imaging of animal extremities demonstrates good technical performance allowing for stable and predictable data acquisition with reasonable agreement between the experimentally measured electromagnetic (EM) field and the simulated EM field within a measurement domain. Using the system, we were able to obtain physiological signatures associated with systolic versus diastolic phases of circulation in an animal extremity, reperfusion versus occlusion phases of the blood supply to the animal's extremity and a compartment syndrome. The imaging results are presented and discussed in the second companion paper.

  11. Extreme Environments and Extreme Science: Reliability and Risk Assessment for Autonomous Systems with Application to Polar Campaigns

    NASA Astrophysics Data System (ADS)

    Trembanis, A.; Griffiths, G.

    2006-12-01

    Assessment of reliability and consequent risk to autonomous systems is an increasingly common and critical concern given the number of challenging new extreme environment research programs calling for the utilization of autonomous systems (e.g. AUVs, gliders, floats, etc.). The interest in using autonomous systems amongst the scientific community is particularly strong amongst polar research programs where so much vital area lies beyond the reach of traditional approaches. Therefore, the potential for scientific discovery is significantly increased, because of the very ability of autonomous systems to get to and gather information in the critical zones. The scientific merits and rewards of polar research are great but so too are the risks. There are risks both to mission success (i.e. science delivery) and risks to asset survival and recovery (i.e. retrieval). In polar settings the greatest increased risks are the complexities of operation (e.g. launch/recovery and retrieval) associated with sea ice and shelf ice. Even in open water settings the temporal and spatial dynamics of environmental conditions complicate the operation of autonomous systems. Very little systematic study and quantitative analysis has been conducted to evaluate the reliability and risk to autonomous systems in any operational setting let alone the demanding and increasingly sought after polar environments. Here we present some assessments of AUV reliability for polar and also non-polar settings drawing largely on datasets from both a large autonomous vehicle program (Autosub) and a small autonomous vehicle program (DOERRI) in order to illustrate key and common elements of reliability and risk that may provide insights to scientific end-users (PIs), program managers, and the developers and operators of other similar autonomous systems working in polar settings. An approach to risk management is laid out. Key risk mitigation elements are presented in categories of system stability and

  12. Systemic inflammation associated with mechanical ventilation among extremely preterm infants

    PubMed Central

    Bose, Carl L.; Laughon, Matthew M.; Allred, Elizabeth N.; O’Shea, T. Michael; Van Marter, Linda J.; Ehrenkranz, Richard A.; Fichorova, Raina N.; Leviton, Alan

    2012-01-01

    Little evidence is available to document that mechanical ventilation is an antecedent of systemic inflammation in preterm humans. We obtained blood on postnatal day 14 from 726 infants born before the 28th week of gestation and measured the concentrations of 25 inflammation-related proteins. We created multivariable models to assess the relationship between duration of ventilation and protein concentrations in the top quartile. Compared to newborns ventilated for fewer than 7 days (N=247), those ventilated for 14 days (N=330) were more likely to have elevated blood concentrations of pro-inflammatory cytokines (IL-1β, TNF-α), chemokines (IL-8, MCP-1), an adhesion molecule (ICAM-1), and a matrix metalloprotease (MMP-9), and less likely to have elevated blood concentrations of two chemokines (RANTES, MIP-1β), a matrix metalloproteinase (MMP-1), and a growth factor (VEGF). Newborns ventilated for 7-13 days (N=149) had systemic inflammation that approximated the pattern of newborns ventilated for 14 days. These relationships were not confounded by chorioamnionitis or antenatal corticosteroid exposure, and were not altered appreciably among infants with and without bacteremia. These findings suggest that two weeks of ventilation are more likely than shorter durations of ventilation to be accompanied by high blood concentrations of pro-inflammatory proteins indicative of systemic inflammation, and by low concentrations of proteins that might protect from inflammation-mediated organ injury. PMID:23148992

  13. Comparison of TLD calibration methods for 192Ir dosimetry.

    PubMed

    Haworth, Annette; Butler, Duncan J; Wilfert, Lisa; Ebert, Martin A; Todd, Stephen P; Hayton, Anna J M; Kron, Tomas

    2013-01-01

    For the purpose of dose measurement using a high-dose rate (192)Ir source, four methods of thermoluminescent dosimeter (TLD) calibration were investigated. Three of the four calibration methods used the (192)Ir source. Dwell times were calculated to deliver 1 Gy to the TLDs irradiated either in air or water. Dwell time calculations were confirmed by direct measurement using an ionization chamber. The fourth method of calibration used 6 MV photons from a medical linear accelerator, and an energy correction factor was applied to account for the difference in sensitivity of the TLDs in (192)Ir and 6 MV. The results of the four TLD calibration methods are presented in terms of the results of a brachytherapy audit where seven Australian centers irradiated three sets of TLDs in a water phantom. The results were in agreement within estimated uncertainties when the TLDs were calibrated with the (192)Ir source. Calibrating TLDs in a phantom similar to that used for the audit proved to be the most practical method and provided the greatest confidence in measured dose. When calibrated using 6 MV photons, the TLD results were consistently higher than the (192)Ir-calibrated TLDs, suggesting this method does not fully correct for the response of the TLDs when irradiated in the audit phantom. PMID:23318392

  14. Monte Carlo simulation of correction factors for IAEA TLD holders.

    PubMed

    Hultqvist, Martha; Fernández-Varea, José M; Izewska, Joanna

    2010-03-21

    The IAEA standard thermoluminescent dosimeter (TLD) holder has been developed for the IAEA/WHO TLD postal dose program for audits of high-energy photon beams, and it is also employed by the ESTRO-QUALity assurance network (EQUAL) and several national TLD audit networks. Factors correcting for the influence of the holder on the TL signal under reference conditions have been calculated in the present work from Monte Carlo simulations with the PENELOPE code for (60)Co gamma-rays and 4, 6, 10, 15, 18 and 25 MV photon beams. The simulation results are around 0.2% smaller than measured factors reported in the literature, but well within the combined standard uncertainties. The present study supports the use of the experimentally obtained holder correction factors in the determination of the absorbed dose to water from the TL readings; the factors calculated by means of Monte Carlo simulations may be adopted for the cases where there are no measured data. PMID:20197601

  15. Reflective optical imaging system for extreme ultraviolet wavelengths

    DOEpatents

    Viswanathan, Vriddhachalam K.; Newnam, Brian E.

    1993-01-01

    A projection reflection optical system has two mirrors in a coaxial, four reflection configuration to reproduce the image of an object. The mirrors have spherical reflection surfaces to provide a very high resolution of object feature wavelengths less than 200 .mu.m, and preferably less than 100 .mu.m. An image resolution of features less than 0.05-0.1 .mu.m, is obtained over a large area field; i.e., 25.4 mm .times.25.4 mm, with a distortion less than 0.1 of the resolution over the image field.

  16. Reflective optical imaging system for extreme ultraviolet wavelengths

    DOEpatents

    Viswanathan, V.K.; Newnam, B.E.

    1993-05-18

    A projection reflection optical system has two mirrors in a coaxial, four reflection configuration to reproduce the image of an object. The mirrors have spherical reflection surfaces to provide a very high resolution of object feature wavelengths less than 200 [mu]m, and preferably less than 100 [mu]m. An image resolution of features less than 0.05-0.1 [mu]m, is obtained over a large area field; i.e., 25.4 mm [times] 25.4 mm, with a distortion less than 0.1 of the resolution over the image field.

  17. Extremal entanglement and mixedness in continuous variable systems

    SciTech Connect

    Adesso, Gerardo; Serafini, Alessio; Illuminati, Fabrizio

    2004-08-01

    We investigate the relationship between mixedness and entanglement for Gaussian states of continuous variable systems. We introduce generalized entropies based on Schatten p norms to quantify the mixedness of a state and derive their explicit expressions in terms of symplectic spectra. We compare the hierarchies of mixedness provided by such measures with the one provided by the purity (defined as tr {rho}{sup 2} for the state {rho}) for generic n-mode states. We then review the analysis proving the existence of both maximally and minimally entangled states at given global and marginal purities, with the entanglement quantified by the logarithmic negativity. Based on these results, we extend such an analysis to generalized entropies, introducing and fully characterizing maximally and minimally entangled states for given global and local generalized entropies. We compare the different roles played by the purity and by the generalized p entropies in quantifying the entanglement and the mixedness of continuous variable systems. We introduce the concept of average logarithmic negativity, showing that it allows a reliable quantitative estimate of continuous variable entanglement by direct measurements of global and marginal generalized p entropies.

  18. Universal persistence exponents in an extremally driven system

    NASA Astrophysics Data System (ADS)

    Head, D. A.

    2002-02-01

    The local persistence R(t), defined as the proportion of the system still in its initial state at time t, is measured for the Bak-Sneppen model. For one and two dimensions, it is found that the decay of R(t) depends on one of two classes of initial configuration. For a subcritical initial state, R(t)~t-θ, where the persistence exponent θ can be expressed in terms of a known universal exponent. Hence θ is universal. Conversely, starting from a supercritical state, R(t) decays by the anomalous form 1-R(t)~tτall until a finite time t0, where τall is also a known exponent. Finally, for the high dimensional model R(t) decays exponentially with a nonuniversal decay constant.

  19. New Phases of Hydrogen-Bonded Systems at Extreme Conditions

    SciTech Connect

    Manaa, M R; Goldman, N; Fried, L E

    2006-10-23

    We study the behavior of hydrogen-bonded systems under high-pressure and temperature. First principle calculations of formic acid under isotropic pressure up to 70 GPa reveal the existence of a polymerization phase at around 20 GPa, in support of recent IR, Raman, and XRD experiments. In this phase, covalent bonding develops between molecules of the same chain through symmetrization of hydrogen bonds. We also performed molecular dynamics simulations of water at pressures up to 115 GPa and 2000 K. Along this isotherm, we are able to define three different phases. We observe a molecular fluid phase with superionic diffusion of the hydrogens for pressure 34 GPa to 58 GPa. We report a transformation to a phase dominated by transient networks of symmetric O-H hydrogen bonds at 95-115 GPa. As in formic acid, the network can be attributed to the symmetrization of the hydrogen bond, similar to the ice VII to ice X transition.

  20. Extreme warm season thunderstorm systems and the urban environment

    NASA Astrophysics Data System (ADS)

    Ntelekos, Alexandros Anastasios

    The consequences of a flood are amplified when it occurs in urban environments by virtue of the large concentration of people and wealth affected. This dissertation is devoted to advancing the understanding of the ways that warm season thunderstorm systems interact with the urban environment to produce flooding. The area of study is the northeastern United States with particular focus over the urban environments of Baltimore, Washington, DC, and New York City. The complex topography of the northeastern United States, with the Appalachian Mountains to the west, and the land-ocean boundary to the east of the heavily urbanized northeastern corridor, presents the analyses with great challenges. At the same time, it increases their relevance since most of the world's urban cores are built close to complex terrain. Warm season thunderstorm systems that produce short-duration, high-intensity rain-fall events are shown to be the major flash flooding agents over the urban corridor of the northeastern US. Established theories of inadvertent weather modification by urban environments are put to the test with the use of advanced models and multiple observational techniques. The results reveal unexplored links of inadvertent weather modification arising from synergies between the urban canopy layer and the land-ocean boundary. Aerosols are also shown to play an important role in rain-fall enhancement, under certain environmental conditions that are examined through combined observational analyses and numerical model experiments. The last part of this dissertation is devoted to synthesizing the links between flooding and the urban environment to perform a critical review of the US flood policy framework. Projections of end-of-the 21st Century annual flood costs are made, and recommendations are provided for a modernization of the policy framework to more efficiently mitigate the effects of floods in the future.

  1. Extremely sensitive dual imaging system in solid phantoms

    PubMed Central

    Barnoy, Eran A.; Fixler, Dror; Popovtzer, Rachela; Nayhoz, Tsviya; Ray, Krishanu

    2016-01-01

    Herein we describe promising results from the combination of fluorescent lifetime imaging microscopy (FLIM) and diffusion reflection (DR) medical imaging techniques. Three different geometries of gold nanoparticles (GNPs) were prepared: spheres of 20nm diameter, rods (GNRs) of aspect ratio (AR) 2.5, and GNRs of AR 3.3. Each GNP geometry was then conjugated using PEG linkers estimated to be 10nm in length to each of 3 different fluorescent dyes: Fluorescein, Rhodamine B, and Sulforhodamine B. DR provided deep-volume measurements (up to 1cm) from within solid, tissue-imitating phantoms, indicating GNR presence corresponding to the light used by recording light scattered from the GNPs with increasing distance to a photodetector. FLIM imaged solutions as well as phantom surfaces, recording both the fluorescence lifetimes as well as the fluorescence intensities. Fluorescence quenching was observed for Fluorescein, while metal-enhanced fluorescence (MEF) was observed in Rhodamine B and Sulforhodamine B – the dyes with an absorption peak at a slightly longer wavelength than the GNP plasmon resonance peak. Our system is highly sensitive due to the increased intensity provided by MEF, and also because of the inherent sensitivity of both FLIM and DR. Together, these two modalities and MEF can provide a lot of meaningful information for molecular and functional imaging of biological samples. PMID:27239085

  2. X- and gamma-ray response of the TLD badge based on CaSO4:Dy Teflon TLD discs.

    PubMed

    Vohra, K G; Pradhan, A S; Bhatt, R C

    1982-09-01

    A TLD badge based on CaSO4: Dy Teflon TLD discs has been designed for personnel monitoring of radiation workers encountering X-rays of effective energies above 20 keV. The badge had two Teflon TLD discs, one of which is used bare (without any filter) and other which is used with a metal filter. By taking into account the TL readout of both of these discs, the problems of photon energy dependence as well as directional dependence of the badge have been reduced to a minimum. The uncertainty due to photon energy dependence above 29 KeV (eff.) was found to be within a value of +/- 15% (at an angle of incidence of 45 degrees). The directional dependence of the badge is within +/- 30% in the energy range from 35 KeV to 1.25 MeV. The badge is designed so as to provide approximate information on the effective photon energy of the X-ray exposures. PMID:7174332

  3. Urbanization, Extreme Events, and Health: The Case for Systems Approaches in Mitigation, Management, and Response.

    PubMed

    Siri, José Gabriel; Newell, Barry; Proust, Katrina; Capon, Anthony

    2016-03-01

    Extreme events, both natural and anthropogenic, increasingly affect cities in terms of economic losses and impacts on health and well-being. Most people now live in cities, and Asian cities, in particular, are experiencing growth on unprecedented scales. Meanwhile, the economic and health consequences of climate-related events are worsening, a trend projected to continue. Urbanization, climate change and other geophysical and social forces interact with urban systems in ways that give rise to complex and in many cases synergistic relationships. Such effects may be mediated by location, scale, density, or connectivity, and also involve feedbacks and cascading outcomes. In this context, traditional, siloed, reductionist approaches to understanding and dealing with extreme events are unlikely to be adequate. Systems approaches to mitigation, management and response for extreme events offer a more effective way forward. Well-managed urban systems can decrease risk and increase resilience in the face of such events. PMID:26219559

  4. Facilitating Co-Design for Extreme-Scale Systems Through Lightweight Simulation

    SciTech Connect

    Engelmann, Christian; Lauer, Frank

    2010-01-01

    This work focuses on tools for investigating algorithm performance at extreme scale with millions of concurrent threads and for evaluating the impact of future architecture choices to facilitate the co-design of high-performance computing (HPC) architectures and applications. The approach focuses on lightweight simulation of extreme-scale HPC systems with the needed amount of accuracy. The prototype presented in this paper is able to provide this capability using a parallel discrete event simulation (PDES), such that a Message Passing Interface (MPI) application can be executed at extreme scale, and its performance properties can be evaluated. The results of an initial prototype are encouraging as a simple 'hello world' MPI program could be scaled up to 1,048,576 virtual MPI processes on a four-node cluster, and the performance properties of two MPI programs could be evaluated at up to 16,384 virtual MPI processes on the same system.

  5. Investigating Operating System Noise in Extreme-Scale High-Performance Computing Systems using Simulation

    SciTech Connect

    Engelmann, Christian

    2013-01-01

    Hardware/software co-design for future-generation high-performance computing (HPC) systems aims at closing the gap between the peak capabilities of the hardware and the performance realized by applications (application-architecture performance gap). Performance profiling of architectures and applications is a crucial part of this iterative process. The work in this paper focuses on operating system (OS) noise as an additional factor to be considered for co-design. It represents the first step in including OS noise in HPC hardware/software co-design by adding a noise injection feature to an existing simulation-based co-design toolkit. It reuses an existing abstraction for OS noise with frequency (periodic recurrence) and period (duration of each occurrence) to enhance the processor model of the Extreme-scale Simulator (xSim) with synchronized and random OS noise simulation. The results demonstrate this capability by evaluating the impact of OS noise on MPI_Bcast() and MPI_Reduce() in a simulated future-generation HPC system with 2,097,152 compute nodes.

  6. TLD assessment of mouse dosimetry during microCT imaging

    SciTech Connect

    Figueroa, Said Daibes; Winkelmann, Christopher T.; Miller, William H.; Volkert, Wynn A.; Hoffman, Timothy J.

    2008-09-15

    Advances in laboratory animal imaging have provided new resources for noninvasive biomedical research. Among these technologies is microcomputed tomography (microCT) which is widely used to obtain high resolution anatomic images of small animals. Because microCT utilizes ionizing radiation for image formation, radiation exposure during imaging is a concern. The objective of this study was to quantify the radiation dose delivered during a standard microCT scan. Radiation dose was measured using thermoluminescent dosimeters (TLDs), which were irradiated employing an 80 kVp x-ray source, with 0.5 mm Al filtration and a total of 54 mA s for a full 360 deg rotation of the unit. The TLD data were validated using a 3.2 cm{sup 3} CT ion chamber probe. TLD results showed a single microCT scan air kerma of 78.0{+-}5.0 mGy when using a poly(methylmethacrylate) (PMMA) anesthesia support module and an air kerma of 92.0{+-}6.0 mGy without the use of the anesthesia module. The validation CT ion chamber study provided a measured radiation air kerma of 81.0{+-}4.0 mGy and 97.0{+-}5.0 mGy with and without the PMMA anesthesia module, respectively. Internal TLD analysis demonstrated an average mouse organ radiation absorbed dose of 76.0{+-}5.0 mGy. The author's results have defined x-ray exposure for a routine microCT study which must be taken into consideration when performing serial molecular imaging studies involving the microCT imaging modality.

  7. TLD assessment of mouse dosimetry during microCT imaging

    PubMed Central

    Figueroa, Said Daibes; Winkelmann, Christopher T.; Miller, William H.; Volkert, Wynn A.; Hoffman, Timothy J.

    2008-01-01

    Advances in laboratory animal imaging have provided new resources for noninvasive biomedical research. Among these technologies is microcomputed tomography (microCT) which is widely used to obtain high resolution anatomic images of small animals. Because microCT utilizes ionizing radiation for image formation, radiation exposure during imaging is a concern. The objective of this study was to quantify the radiation dose delivered during a standard microCT scan. Radiation dose was measured using thermoluminescent dosimeters (TLDs), which were irradiated employing an 80 kVp x-ray source, with 0.5 mm Al filtration and a total of 54 mA s for a full 360 deg rotation of the unit. The TLD data were validated using a 3.2 cm3 CT ion chamber probe. TLD results showed a single microCT scan air kerma of 78.0±5.0 mGy when using a poly(methylmethacrylate) (PMMA) anesthesia support module and an air kerma of 92.0±6.0 mGy without the use of the anesthesia module. The validation CT ion chamber study provided a measured radiation air kerma of 81.0±4.0 mGy and 97.0±5.0 mGy with and without the PMMA anesthesia module, respectively. Internal TLD analysis demonstrated an average mouse organ radiation absorbed dose of 76.0±5.0 mGy. The author’s results have defined x-ray exposure for a routine microCT study which must be taken into consideration when performing serial molecular imaging studies involving the microCT imaging modality. PMID:18841837

  8. Relative Efficiency Of TLD-100 Exposed to X-Rays

    SciTech Connect

    Ixquiac-Cabrera, J. M.; Gamboa-de Buen, I.; Avila, O.; Brandan, M. E.

    2008-08-11

    The relative efficiency of TLD-100 (LiF:Mg,Ti) exposed to X-rays in the range from 30 to 250 kV, with respect to {sup 60}CO gamma rays has been measured. Glow curves were deconvoluted into peaks 3 to 9. All efficiencies were greater than 1 having a maximum of 1.38 for the dosimetric region (peaks 3+4+5) and peaks 4, 5 and 9, and 2.2 for peaks 6a, 6b, 7 and 8 at the effective energy of 24 keV.

  9. Combination TLD/TED dose assessment

    SciTech Connect

    Parkhurst, M.A.

    1992-11-01

    During the early 1980s, an appraisal of dosimetry programs at US Department of Energy (DOE) facilities identified a significant weakness in dose assessment in fast neutron environments. Basing neutron dose equivalent on thermoluminescence dosimeters (TLDS) was not entirely satisfactory for environments that had not been well characterized. In most operational situations, the dosimeters overrespond to neutrons, and this overresponse could be further exaggerated with changes in the neutron quality factor (Q). Because TLDs are energy dependent with an excellent response to thermal and low-energy neutrons but a weak response to fast neutrons, calibrating the dosimetry system to account for mixed and moderated neutron energy fields is a difficult and seldom satisfactory exercise. To increase the detection of fast neutrons and help improve the accuracy of dose equivalent determinations, a combination dosimeter was developed using TLDs to detect thermal and low-energy neutrons and a track-etch detector (TED) to detect fast neutrons. By combining the albedo energy response function of the TLDs with the track detector elements, the dosimeter can nearly match the fluence-to-dose equivalent conversion curve. The polymer CR-39 has neutron detection characteristics superior to other materials tested. The CR-39 track detector is beta and gamma insensitive and does not require backscatter (albedo) from the body to detect the exposure. As part of DOE's Personnel Neutron and Upgrade Program, we have been developing a R-39 track detector over the past decade to address detection and measurement of fast neutrons. Using CR-39 TEDs in combination with TLDs will now allow us to detect the wide spectrum of occupational neutron energies and assign dose equivalents much more confidently.

  10. Combination TLD/TED dose assessment

    SciTech Connect

    Parkhurst, M.A.

    1992-11-01

    During the early 1980s, an appraisal of dosimetry programs at US Department of Energy (DOE) facilities identified a significant weakness in dose assessment in fast neutron environments. Basing neutron dose equivalent on thermoluminescence dosimeters (TLDS) was not entirely satisfactory for environments that had not been well characterized. In most operational situations, the dosimeters overrespond to neutrons, and this overresponse could be further exaggerated with changes in the neutron quality factor (Q). Because TLDs are energy dependent with an excellent response to thermal and low-energy neutrons but a weak response to fast neutrons, calibrating the dosimetry system to account for mixed and moderated neutron energy fields is a difficult and seldom satisfactory exercise. To increase the detection of fast neutrons and help improve the accuracy of dose equivalent determinations, a combination dosimeter was developed using TLDs to detect thermal and low-energy neutrons and a track-etch detector (TED) to detect fast neutrons. By combining the albedo energy response function of the TLDs with the track detector elements, the dosimeter can nearly match the fluence-to-dose equivalent conversion curve. The polymer CR-39 has neutron detection characteristics superior to other materials tested. The CR-39 track detector is beta and gamma insensitive and does not require backscatter (albedo) from the body to detect the exposure. As part of DOE`s Personnel Neutron and Upgrade Program, we have been developing a R-39 track detector over the past decade to address detection and measurement of fast neutrons. Using CR-39 TEDs in combination with TLDs will now allow us to detect the wide spectrum of occupational neutron energies and assign dose equivalents much more confidently.

  11. Development of an Interactive Upper Extremity Gestural Robotic Feedback System: From Bench to Reality

    PubMed Central

    Wood, Krista A. Coleman; Lathan, Corinna E.; Kaufman, Kenton R.

    2010-01-01

    Development of an interactive system to treat patients with movement impairments of the upper extremity is described. Gestures and movement of patients as instructed by therapists are detected by accelerometers and feedback is provided directly to the patient via a robot. PMID:19964144

  12. Hypersaline microbial systems of sabkhas: examples of life's survival in "extreme" conditions.

    PubMed

    Krumbein, Wolfgang Elisabeth; Gorbushina, Anna A; Holtkamp-Tacken, Elisabeth

    2004-01-01

    Life and living systems need several important factors to establish themselves and to have a continued tradition. In this article the nature of the borderline situation for microbial life under heavy salt stress is analyzed and discussed using the example of biofilms and microbial mats of sabkha systems of the Red Sea. Important factors ruling such environments are described, and include the following: (1) Microbial life is better suited for survival in extremely changing and only sporadically water-supplied environments than are larger organisms (including humans). (2) Microbial life shows extremely poikilophilic adaptation patterns to conditions that deviate significantly from conditions normal for life processes on Earth today. (3) Microbial life adapts itself to such extremely changing and only ephemerally supportive conditions by the capacity of extreme changes (a) in morphology (pleomorphy), (b) in metabolic patterns (poikilotrophy), (c) in survival strategies (poikilophily), and (d) by trapping and enclosing all necessary sources of energy matter in an inwardly oriented diffusive cycle. All this is achieved without any serious attempt at escaping from the extreme and extremely changing conditions. Furthermore, these salt swamp systems are geophysiological generators of energy and material reservoirs recycled over a geological time scale. Neither energy nor material is wasted for propagation by spore formation. This capacity is summarized as poikilophilic and poikilotroph behavior of biofilm or microbial mat communities in salt and irradiationstressed environmental conditions of the sabkha or salt desert type. We use mainly cyanobacteria as an example, although other bacteria and even eukaryotic fungi may exhibit the same potential of living and surviving under conditions usually not suitable for life on Earth. It may, however, be postulated that such poikilophilic organisms are the true candidates for life support and survival under conditions never recorded

  13. Design and optimization of a dedicated cone-beam CT system for musculoskeletal extremities imaging

    NASA Astrophysics Data System (ADS)

    Zbijewski, W.; De Jean, P.; Prakash, P.; Ding, Y.; Stayman, J. W.; Packard, N.; Senn, R.; Yang, D.; Yorkston, J.; Machado, A.; Carrino, J. A.; Siewerdsen, J. H.

    2011-03-01

    The design, initial imaging performance, and model-based optimization of a dedicated cone-beam CT (CBCT) scanner for musculoskeletal extremities is presented. The system offers a compact scanner that complements conventional CT and MR by providing sub-mm isotropic spatial resolution, the ability to image weight-bearing extremities, and the capability for integrated real-time fluoroscopy and digital radiography. The scanner employs a flat-panel detector and a fixed anode x-ray source and has a field of view of ~ (20x20x20) cm3. The gantry allows a "standing" configuration for imaging of weight-bearing lower extremities and a "sitting" configuration for imaging of upper extremities and unloaded lower extremities. Cascaded systems analysis guided the selection of x-ray technique (e.g., kVp, filtration, and dose) and system design (e.g., magnification factor), yielding input-quantum-limited performance at detector signal of 100 times the electronic noise, while maintaining patient dose below 5 mGy (a factor of ~2-3 less than conventional CT). A magnification of 1.3 optimized tradeoffs between source and detector blur for a 0.5 mm focal spot. A custom antiscatter grid demonstrated significant reduction of artifacts without loss of contrast-to-noise ratio or increase in dose. Image quality in cadaveric specimens was assessed on a CBCT bench, demonstrating exquisite bone detail, visualization of intra-articular morphology, and soft-tissue visibility approaching that of diagnostic CT. The capability to image loaded extremities and conduct multi-modality CBCT/fluoroscopy with improved workflow compared to whole-body CT could be of value in a broad spectrum of applications, including orthopaedics, rheumatology, surgical planning, and treatment assessment. A clinical prototype has been constructed for deployment in pilot study trials.

  14. Hypersaline Microbial Systems of Sabkhas: Examples of Life's Survival in "Extreme" Conditions

    NASA Astrophysics Data System (ADS)

    Krumbein, Wolfgang Elisabeth; Gorbushina, Anna A.; Holtkamp-Tacken, Elisabeth

    2004-12-01

    Life and living systems need several important factors to establish themselves and to have a continued tradition. In this article the nature of the borderline situation for microbial life under heavy salt stress is analyzed and discussed using the example of biofilms and microbial mats of sabkha systems of the Red Sea. Important factors ruling such environments are described, and include the following: (1) Microbial life is better suited for survival in extremely changing and only sporadically water-supplied environments than are larger organisms (including humans). (2) Microbial life shows extremely poikilophilic adaptation patterns to conditions that deviate significantly from conditions normal for life processes on Earth today. (3) Microbial life adapts itself to such extremely changing and only ephemerally supportive conditions by the capacity of extreme changes (a) in morphology (pleomorphy), (b) in metabolic patterns (poikilotrophy), (c) in survival strategies (poikilophily), and (d) by trapping and enclosing all necessary sources of energy matter in an inwardly oriented diffusive cycle. All this is achieved without any serious attempt at escaping from the extreme and extremely changing conditions. Furthermore, these salt swamp systems are geophysiological generators of energy and material reservoirs recycled over a geological time scale. Neither energy nor material is wasted for propagation by spore formation. This capacity is summarized as poikilophilic and poikilotroph behavior of biofilm or microbial mat communities in salt and irradiationstressed environmental conditions of the sabkha or salt desert type. We use mainly cyanobacteria as an example, although other bacteria and even eukaryotic fungi may exhibit the same potential of living and surviving under conditions usually not suitable for life on Earth. It may, however, be postulated that such poikilophilic organisms are the true candidates for life support and survival under conditions never recorded

  15. Linearized stability of extreme shock profiles for systems of conservation laws with viscosity

    NASA Astrophysics Data System (ADS)

    Pego, R. L.

    1982-12-01

    For a genuinely nonlinear hyperbolic system of conservation laws with added artificial viscosity, we prove that traveling wave profiles for small amplitude extreme shocks (the slowest and fastest) are linearly stable to perturbations initial data chosen from certain spaces with weighted norm; i.e., we show that the spectrum of the linearized equation lies strictly in the left half plane, except for a simple eigenvalue at the origin (due to phase translations of the profile). The weight is used in components transverse to the profile, where, for an extreme shock, the linearized equation is dominated by unidirectional convection.

  16. Patterns and singular features of extreme fluctuational paths of a periodically driven system

    NASA Astrophysics Data System (ADS)

    Chen, Zhen; Liu, Xianbin

    2016-05-01

    Large fluctuations of an overdamped periodically driven oscillating system are investigated theoretically and numerically in the limit of weak noise. Optimal paths fluctuating to certain point are given by statistical analysis using the concept of prehistory probability distribution. The validity of statistical results is verified by solutions of boundary value problem. Optimal paths are found to change topologically when terminating points lie at opposite side of a switching line. Patterns of extreme paths are plotted through a proper parameterization of Lagrangian manifold having complicated structures. Several extreme paths to the same point are obtained by multiple solutions of boundary value solutions. Actions along various extreme paths are calculated and associated analysis is performed in relation to the singular features of the patterns.

  17. Extreme weather events: Should drinking water quality management systems adapt to changing risk profiles?

    PubMed

    Khan, Stuart J; Deere, Daniel; Leusch, Frederic D L; Humpage, Andrew; Jenkins, Madeleine; Cunliffe, David

    2015-11-15

    Among the most widely predicted and accepted consequences of global climate change are increases in both the frequency and severity of a variety of extreme weather events. Such weather events include heavy rainfall and floods, cyclones, droughts, heatwaves, extreme cold, and wildfires, each of which can potentially impact drinking water quality by affecting water catchments, storage reservoirs, the performance of water treatment processes or the integrity of distribution systems. Drinking water guidelines, such as the Australian Drinking Water Guidelines and the World Health Organization Guidelines for Drinking-water Quality, provide guidance for the safe management of drinking water. These documents present principles and strategies for managing risks that may be posed to drinking water quality. While these principles and strategies are applicable to all types of water quality risks, very little specific attention has been paid to the management of extreme weather events. We present a review of recent literature on water quality impacts of extreme weather events and consider practical opportunities for improved guidance for water managers. We conclude that there is a case for an enhanced focus on the management of water quality impacts from extreme weather events in future revisions of water quality guidance documents. PMID:26311274

  18. Microwave tomography of extremities: 1) Dedicated 2D system and physiological signatures

    PubMed Central

    Semenov, Serguei; Kellam, James; Sizov, Yuri; Nazarov, Alexei; Williams, Thomas; Nair, Bindu; Pavlovsky, Andrey; Posukh, Vitaly; Quinn, Michael

    2011-01-01

    Microwave Tomography (MWT) is a novel imaging modality which might be applicable for non-invasive assessment of functional and pathological conditions of biological tissues. The imaging of the soft tissue of extremities is one of its potential applications. The feasibility of this technology for such applications was demonstrated earlier. This is the first of two companion papers focused on an application of MWT for imaging of the extremity’s soft tissues. The goal of this study is to assess the technical performance of the developed 2D MWT system dedicated for imaging of functional and pathological conditions of the extremity’s soft tissues. Specifically, the system’s performance was tested by its ability to detect signals associated with physiological activity and soft tissue interventions (circulatory related changes, blood flow reduction and a simulated compartmental syndrome) – so called “physiological signatures”. The developed 2D MWT system dedicated for an imaging of animal extremities demonstrates good technical performance allowing for stable and predictable data acquisition with reasonable agreement between experimentally measured electromagnetic (EM) field and simulated EM field within a measurement domain. Using the system we were able to obtain physiological signatures associated with systolic vs diastolic phases of circulation in an animal extremity, reperfusion vs occlusion phases of the blood supply to the animal’s extremity and the a compartment syndrome. The imaging results are presented and discussed in the second companion paper. PMID:21364265

  19. Investigation of radiation doses in open space using TLD detectors.

    PubMed

    Reitz, G; Facius, R; Bilski, P; Olko, P

    2002-01-01

    The low energy component of the cosmic radiation field is strongly modified by the shielding of the spacecraft and it is time and location dependent. Thermoluminescent lithium fluoride detectors have been applied to determine the radiation doses inside the ESA-Facility BIOPAN. The BIOPAN facility was mounted outside and launched on a Foton spacecraft and opened to space to allow exposure of several experiments to open space. Standard TLD-600. TLD-700 chips, two layers MTS-Ns sintered pellets with different effective thickness of the sensitive layer and MTS-N of different thickness have been exposed with different shielding thicknesses in front of them. The measured TL signal in the 0.1 mm thick detector just shielded by an aluminised Kapton foil of 25 microm thickness in front yielded a dose of 29.8 Gy (calibrated with 137Cs gamma rays) for an exposure time of 12.7 days: after 2.5 g.cm(-2) shielding the doses dropped to 3 mGy. The monitoring of radiation doses and its depth dose distribution outside the spacecraft are of great interest for radiation protection of astronauts working in open space. The knowledge of depth-dose distribution is a prerequisite to determine the organ doses an astronaut will receive during an extravehicular activity (EVA). The BIOPAN experiments are to be continued in the future. PMID:12382937

  20. Development of a wafer positioning system for the Sandia extreme ultraviolet lithography tool

    SciTech Connect

    Wronosky, J.B.; Smith, T.G.; Darnold, J.R.

    1995-12-01

    A wafer positioning system was recently developed by Sandia National Laboratories for an Extreme Ultraviolet Lithography (EUVL) tool. The system, which utilizes a magnetically levitated fine stage to provide ultra-precise positioning in all six degrees of freedom, incorporates technological improvements resulting from four years of prototype development. This paper describes the design, implementation, and functional capability of the system. Specifics regarding control system electronics, including software and control algorithm structure, as well as performance design goals and test results are presented. Potential system enhancements, some of which are in process, are also discussed.

  1. Development of a Wafer Positioning System for the Sandia Extreme Ultraviolet Lithography Tool

    NASA Technical Reports Server (NTRS)

    Wronosky, John B.; Smith, Tony G.; Darnold, Joel R.

    1996-01-01

    A wafer positioning system was recently developed by Sandia National Laboratories for an Extreme Ultraviolet Lithography (EUVL) tool. The system, which utilizes a magnetically levitated fine stage to provide ultra-precise positioning in all six degrees of freedom, incorporates technological improvements resulting from four years of prototype development. This paper describes the design, implementation, and functional capability of the system. Specifics regarding control system electronics, including software and control algorithm structure, as well as performance design goals and test results are presented. Potential system enhancements, some of which are in process, are also discussed.

  2. Co-Alignment System (CAS) study. Report on task 1-3. [Solar Extreme Ultraviolet Telescope and Spectrometer pointing system

    NASA Technical Reports Server (NTRS)

    Anderson, N. T.

    1980-01-01

    The design of a suitable coalignment system (CAS) for the Solar Extreme Ultraviolet Telescope and Spectrometer (SEUTS) is presented. The CAS provides offset adjustment capabilities to SEUTS which will be mounted on a single large pointing system with other devices. The suitability of existing designs is determined and modifications are suggested.

  3. Extreme temperature trends in major cropping systems and their relation to agricultural land use change

    NASA Astrophysics Data System (ADS)

    Mueller, N. D.; Butler, E. E.; McKinnon, K. A.; Rhines, A. N.; Tingley, M.; Siebert, S.; Holbrook, N. M.; Huybers, P. J.

    2015-12-01

    High temperature extremes during the growing season can reduce agricultural production. At the same time, agricultural practices can modify temperatures by altering the surface energy budget. Here we investigate growing season climate trends in major cropping systems and their relationship with agricultural land use change. In the US Midwest, 100-year trends exhibit a transition towards more favorable conditions, with cooler summer temperature extremes and increased precipitation. Statistically significant correspondence is found between the cooling pattern and trends in cropland intensification, as well as with trends towards greater irrigated land over a small subset of the domain. Land conversion to cropland, often considered an important influence on historical temperatures, is not significantly associated with cooling. We suggest that cooling is primarily associated with agricultural intensification increasing the potential for evapotranspiration, consistent with our finding that cooling trends are greatest for the highest temperature percentiles, and that increased evapotranspiration generally leads to greater precipitation. Temperatures over rainfed croplands show no cooling trend during drought conditions, consistent with evapotranspiration requiring adequate soil moisture, and implying that modern drought events feature greater warming as baseline cooler temperatures revert to historically high extremes. Preliminary results indicate these relationships between temperature extremes, irrigation, and intensification are also observed in other major summer cropping systems, including northeast China, Argentina, and the Canadian Prairies.

  4. SAXO: the extreme adaptive optics system of SPHERE (I) system overview and global laboratory performance

    NASA Astrophysics Data System (ADS)

    Sauvage, Jean-Francois; Fusco, Thierry; Petit, Cyril; Costille, Anne; Mouillet, David; Beuzit, Jean-Luc; Dohlen, Kjetil; Kasper, Markus; Suarez, Marcos; Soenke, Christian; Baruffolo, Andrea; Salasnich, Bernardo; Rochat, Sylvain; Fedrigo, Enrico; Baudoz, Pierre; Hugot, Emmanuel; Sevin, Arnaud; Perret, Denis; Wildi, Francois; Downing, Mark; Feautrier, Philippe; Puget, Pascal; Vigan, Arthur; O'Neal, Jared; Girard, Julien; Mawet, Dimitri; Schmid, Hans Martin; Roelfsema, Ronald

    2016-04-01

    The direct imaging of exoplanet is a leading field of today's astronomy. The photons coming from the planet carry precious information on the chemical composition of its atmosphere. The second-generation instrument, Spectro-Polarimetric High contrast Exoplanet Research (SPHERE), dedicated to detection, photometry and spectral characterization of Jovian-like planets, is now in operation on the European very large telescope. This instrument relies on an extreme adaptive optics (XAO) system to compensate for atmospheric turbulence as well as for internal errors with an unprecedented accuracy. We demonstrate the high level of performance reached by the SPHERE XAO system (SAXO) during the assembly integration and test (AIT) period. In order to fully characterize the instrument quality, two AIT periods have been mandatory. In the first phase at Observatoire de Paris, the performance of SAXO itself was assessed. In the second phase at IPAG Grenoble Observatory, the operation of SAXO in interaction with the overall instrument has been optimized. In addition to the first two phases, a final check has been performed after the reintegration of the instrument at Paranal Observatory, in the New Integration Hall before integration at the telescope focus. The final performance aimed by the SPHERE instrument with the help of SAXO is among the highest Strehl ratio pretended for an operational instrument (90% in H band, 43% in V band in a realistic turbulence r0, and wind speed condition), a limit R magnitude for loop closure at 15, and a robustness to high wind speeds. The full-width at half-maximum reached by the instrument is 40 mas for infrared in H band and unprecedented 18.5 mas in V band.

  5. The LANL model 8823 whole-body TLD and associated dose algorithm

    SciTech Connect

    Hoffman, J.M.; Mallett, M.W.

    1999-11-01

    The Los Alamos National Laboratory Model 8823 whole-body TLD has been designed to perform accurate dose estimates for beta, photon, and neutron radiations that are encountered in pure calibration, mixed calibration, and typical field radiation conditions. The radiation energies and field types for which the Model 8823 dosimeter is capable of measuring are described. The Model 8823 dosimeter has been accredited for all performance testing categories in the Department of Energy Laboratory Accrediation Program for external dosimetry systems. The philosophy used in the design of the Model 8823 dosimeter and the associated dose algorithm is to isolate the responses due to beta, photon, and neutron radiations; obtain radiation quality information; and make functional adjustments to the elemental readings to estimate the dose equivalent at 7, 300, and 1,000 mg cm{sup {minus}2}, representing the required reporting quantities for shallow, lens-of-the-eye, and deep dose, respectively.

  6. Application of laser TLD 2-dimensional dose mapping in medical physics

    SciTech Connect

    Braunlich, P.F.; Jones, S.C.

    1995-12-31

    IST, Inc. has developed a laser-based system for rapid evaluation of two-dimensional monolithic thermoluminescence dosimetry (TLD) films. For most applications, the authors use arrays of 1.5- mm diameter, 38-{mu}m-thick TLDs, deposited on 0.125-mm-thick polymer in a 3x3-mm grid of up to 30x30-cm size. Continuous films are available for applications requiring higher spatial resolution (300 {mu}m.) The films are re-usable and water-immersible. Results from radiation therapy (photon and charged particle beam) dose measurements, quality assurance in mammography (dose distribution and kVp), interventional radiotherapy and personnel dosimetry (detection of intentional fraudulent exposures) are given.

  7. Multiplex APLP System for High-Resolution Haplogrouping of Extremely Degraded East-Asian Mitochondrial DNAs.

    PubMed

    Kakuda, Tsuneo; Shojo, Hideki; Tanaka, Mayumi; Nambiar, Phrabhakaran; Minaguchi, Kiyoshi; Umetsu, Kazuo; Adachi, Noboru

    2016-01-01

    Mitochondrial DNA (mtDNA) serves as a powerful tool for exploring matrilineal phylogeographic ancestry, as well as for analyzing highly degraded samples, because of its polymorphic nature and high copy numbers per cell. The recent advent of complete mitochondrial genome sequencing has led to improved techniques for phylogenetic analyses based on mtDNA, and many multiplex genotyping methods have been developed for the hierarchical analysis of phylogenetically important mutations. However, few high-resolution multiplex genotyping systems for analyzing East-Asian mtDNA can be applied to extremely degraded samples. Here, we present a multiplex system for analyzing mitochondrial single nucleotide polymorphisms (mtSNPs), which relies on a novel amplified product-length polymorphisms (APLP) method that uses inosine-flapped primers and is specifically designed for the detailed haplogrouping of extremely degraded East-Asian mtDNAs. We used fourteen 6-plex polymerase chain reactions (PCRs) and subsequent electrophoresis to examine 81 haplogroup-defining SNPs and 3 insertion/deletion sites, and we were able to securely assign the studied mtDNAs to relevant haplogroups. Our system requires only 1×10-13 g (100 fg) of crude DNA to obtain a full profile. Owing to its small amplicon size (<110 bp), this new APLP system was successfully applied to extremely degraded samples for which direct sequencing of hypervariable segments using mini-primer sets was unsuccessful, and proved to be more robust than conventional APLP analysis. Thus, our new APLP system is effective for retrieving reliable data from extremely degraded East-Asian mtDNAs. PMID:27355212

  8. Multiplex APLP System for High-Resolution Haplogrouping of Extremely Degraded East-Asian Mitochondrial DNAs

    PubMed Central

    Kakuda, Tsuneo; Shojo, Hideki; Tanaka, Mayumi; Nambiar, Phrabhakaran; Minaguchi, Kiyoshi; Umetsu, Kazuo; Adachi, Noboru

    2016-01-01

    Mitochondrial DNA (mtDNA) serves as a powerful tool for exploring matrilineal phylogeographic ancestry, as well as for analyzing highly degraded samples, because of its polymorphic nature and high copy numbers per cell. The recent advent of complete mitochondrial genome sequencing has led to improved techniques for phylogenetic analyses based on mtDNA, and many multiplex genotyping methods have been developed for the hierarchical analysis of phylogenetically important mutations. However, few high-resolution multiplex genotyping systems for analyzing East-Asian mtDNA can be applied to extremely degraded samples. Here, we present a multiplex system for analyzing mitochondrial single nucleotide polymorphisms (mtSNPs), which relies on a novel amplified product-length polymorphisms (APLP) method that uses inosine-flapped primers and is specifically designed for the detailed haplogrouping of extremely degraded East-Asian mtDNAs. We used fourteen 6-plex polymerase chain reactions (PCRs) and subsequent electrophoresis to examine 81 haplogroup-defining SNPs and 3 insertion/deletion sites, and we were able to securely assign the studied mtDNAs to relevant haplogroups. Our system requires only 1×10−13 g (100 fg) of crude DNA to obtain a full profile. Owing to its small amplicon size (<110 bp), this new APLP system was successfully applied to extremely degraded samples for which direct sequencing of hypervariable segments using mini-primer sets was unsuccessful, and proved to be more robust than conventional APLP analysis. Thus, our new APLP system is effective for retrieving reliable data from extremely degraded East-Asian mtDNAs. PMID:27355212

  9. Extreme multistability in a memristor-based multi-scroll hyper-chaotic system

    NASA Astrophysics Data System (ADS)

    Yuan, Fang; Wang, Guangyi; Wang, Xiaowei

    2016-07-01

    In this paper, a new memristor-based multi-scroll hyper-chaotic system is designed. The proposed memristor-based system possesses multiple complex dynamic behaviors compared with other chaotic systems. Various coexisting attractors and hidden coexisting attractors are observed in this system, which means extreme multistability arises. Besides, by adjusting parameters of the system, this chaotic system can perform single-scroll attractors, double-scroll attractors, and four-scroll attractors. Basic dynamic characteristics of the system are investigated, including equilibrium points and stability, bifurcation diagrams, Lyapunov exponents, and so on. In addition, the presented system is also realized by an analog circuit to confirm the correction of the numerical simulations.

  10. Extreme multistability in a memristor-based multi-scroll hyper-chaotic system.

    PubMed

    Yuan, Fang; Wang, Guangyi; Wang, Xiaowei

    2016-07-01

    In this paper, a new memristor-based multi-scroll hyper-chaotic system is designed. The proposed memristor-based system possesses multiple complex dynamic behaviors compared with other chaotic systems. Various coexisting attractors and hidden coexisting attractors are observed in this system, which means extreme multistability arises. Besides, by adjusting parameters of the system, this chaotic system can perform single-scroll attractors, double-scroll attractors, and four-scroll attractors. Basic dynamic characteristics of the system are investigated, including equilibrium points and stability, bifurcation diagrams, Lyapunov exponents, and so on. In addition, the presented system is also realized by an analog circuit to confirm the correction of the numerical simulations. PMID:27475067

  11. Cutoff low systems and their relevance to large-scale extreme precipitation in the European Alps

    NASA Astrophysics Data System (ADS)

    Awan, N. K.; Formayer, H.

    2016-03-01

    In this paper, we attempt to highlight the relevance of cutoff low systems (CoLs) to large-scale heavy precipitation events within the Alpine region which often lead to catastrophic flooding. The main results of this study are (1) a detailed climatology (1971-1999) of CoLs for the European region, (2) contribution of CoLs to extreme precipitation events in the European Alpine region, (3) identification of regions within the European Alps most affected by extreme precipitation caused by CoLs, and (4) identification of regions where presence of CoLs is related to extreme precipitation in the Alpine region. The findings of this paper suggest that CoLs have a significant correlation with extreme precipitation events and strongly influence the climate of the Alpine region. The total contribution of CoLs to large-scale heavy precipitation events ranges between 20 and 95 % and is most pronounced in the northern and eastern parts of the Alps. More than 80 % of the events occur in the summer season. The area around the Alps and West of Spain (over the Atlantic Ocean) is the most affected region. The location of the center of CoLs that affect the Alpine region most occur on the northern and southern sides of the Alpine ridge.

  12. Complex networks identify spatial patterns of extreme rainfall events of the South American Monsoon System

    NASA Astrophysics Data System (ADS)

    Boers, Niklas; Bookhagen, Bodo; Marwan, Norbert; Kurths, Jürgen; Marengo, José

    2013-08-01

    We investigate the spatial characteristics of extreme rainfall synchronicity of the South American Monsoon System (SAMS) by means of Complex Networks (CN). By introducing a new combination of CN measures and interpreting it in a climatic context, we investigate climatic linkages and classify the spatial characteristics of extreme rainfall synchronicity. Although our approach is based on only one variable (rainfall), it reveals the most important features of the SAMS, such as the main moisture pathways, areas with frequent development of Mesoscale Convective Systems (MCS), and the major convergence zones. In addition, our results reveal substantial differences between the spatial structures of rainfall synchronicity above the 90th and above the 95th percentiles. Most notably, events above the 95th percentile contribute stronger to MCS in the La Plata Basin.

  13. Rule based artificial intelligence expert system for determination of upper extremity impairment rating.

    PubMed

    Lim, I; Walkup, R K; Vannier, M W

    1993-04-01

    Quantitative evaluation of upper extremity impairment, a percentage rating most often determined using a rule based procedure, has been implemented on a personal computer using an artificial intelligence, rule-based expert system (AI system). In this study, the rules given in Chapter 3 of the AMA Guides to the Evaluation of Permanent Impairment (Third Edition) were used to develop such an AI system for the Apple Macintosh. The program applies the rules from the Guides in a consistent and systematic fashion. It is faster and less error-prone than the manual method, and the results have a higher degree of precision, since intermediate values are not truncated. PMID:8334872

  14. Design implementation and migration of security systems as an extreme project.

    SciTech Connect

    Scharmer, Carol

    2010-10-01

    Decision Trees, algorithms, software code, risk management, reports, plans, drawings, change control, presentations, and analysis - all useful tools and efforts but time consuming, resource intensive, and potentially costly for projects that have absolute schedule and budget constraints. What are necessary and prudent efforts when a customer calls with a major security problem that needs to be fixed with a proven, off-the-approval-list, multi-layered integrated system with high visibility and limited funding and expires at the end of the Fiscal Year? Whether driven by budget cycles, safety, or by management decree, many such projects begin with generic scopes and funding allocated based on a rapid management 'guestimate.' Then a Project Manager (PM) is assigned a project with a predefined and potentially limited scope, compressed schedule, and potentially insufficient funding. The PM is tasked to rapidly and cost effectively coordinate a requirements-based design, implementation, test, and turnover of a fully operational system to the customer, all while the customer is operating and maintaining an existing security system. Many project management manuals call this an impossible project that should not be attempted. However, security is serious business and the reality is that rapid deployment of proven systems via an 'Extreme Project' is sometimes necessary. Extreme Projects can be wildly successful but require a dedicated team of security professionals lead by an experienced project manager using a highly-tailored and agile project management process with management support at all levels, all combined with significant interface with the customer. This paper does not advocate such projects or condone eliminating the valuable analysis and project management techniques. Indeed, having worked on a well-planned project provides the basis for experienced team members to complete Extreme Projects. This paper does, however, provide insight into what it takes for projects

  15. Design, implementation and migration of security systems as an extreme project.

    SciTech Connect

    Scharmer, Carol; Trujillo, David

    2010-08-01

    Decision Trees, algorithms, software code, risk management, reports, plans, drawings, change control, presentations, and analysis - all useful tools and efforts but time consuming, resource intensive, and potentially costly for projects that have absolute schedule and budget constraints. What are necessary and prudent efforts when a customer calls with a major security problem that needs to be fixed with a proven, off-the-approval-list, multi-layered integrated system with high visibility and limited funding and expires at the end of the Fiscal Year? Whether driven by budget cycles, safety, or by management decree, many such projects begin with generic scopes and funding allocated based on a rapid management 'guestimate.' Then a Project Manager (PM) is assigned a project with a predefined and potentially limited scope, compressed schedule, and potentially insufficient funding. The PM is tasked to rapidly and cost effectively coordinate a requirements-based design, implementation, test, and turnover of a fully operational system to the customer, all while the customer is operating and maintaining an existing security system. Many project management manuals call this an impossible project that should not be attempted. However, security is serious business and the reality is that rapid deployment of proven systems via an 'Extreme Project' is sometimes necessary. Extreme Projects can be wildly successful but require a dedicated team of security professionals lead by an experienced project manager using a highly-tailored and agile project management process with management support at all levels, all combined with significant interface with the customer. This paper does not advocate such projects or condone eliminating the valuable analysis and project management techniques. Indeed, having worked on a well-planned project provides the basis for experienced team members to complete Extreme Projects. This paper does, however, provide insight into what it takes for projects

  16. Characteristics of mesoscale-convective-system-produced extreme rainfall over southeastern South Korea: 7 July 2009

    NASA Astrophysics Data System (ADS)

    Jeong, Jong-Hoon; Lee, Dong-In; Wang, Chung-Chieh; Han, In-Seong

    2016-04-01

    An extreme-rainfall-producing mesoscale convective system (MCS) associated with the Changma front in southeastern South Korea was investigated using observational data. This event recorded historic rainfall and led to devastating flash floods and landslides in the Busan metropolitan area on 7 July 2009. The aim of the present study is to analyse the influences for the synoptic and mesoscale environment, and the reasons that the quasi-stationary MCS causes extreme rainfall. Synoptic and mesoscale analyses indicate that the MCS and heavy rainfall occurred in association with a stationary front which resembled a warm front in structure. A strong southwesterly low-level jet (LLJ) transported warm and humid air and supplied the moisture toward the front, and the air rose upwards above the frontal surface. As the moist air was conditionally unstable, repeated upstream initiation of deep convection by back-building occurred at the coastline, while old cells moved downstream parallel to the convective line with training effect. Because the motion of convective cells nearly opposed the backward propagation, the system as a whole moved slowly. The back-building behaviour was linked to the convectively generated cold pool and its outflow boundary, which played a role in the propagation and maintenance of the rainfall system. As a result, the quasi-stationary MCS caused a prolonged duration of heavy rainfall, leading to extreme rainfall over the Busan metropolitan area.

  17. NRC TLD direct radiation monitoring network: Volume 15, No. 3. Progress report, July--September 1995

    SciTech Connect

    Struckmeyer, R.

    1995-12-01

    The US Nuclear Regulatory Commission (NRC) Direct Radiation Monitoring Network is operated by the NRC in cooperation with participating states to provide continuous measurement of the ambient radiation levels around licensed NRC facilities, primarily power reactors. Ambient radiation levels result from naturally occurring radionuclides present in the soil, cosmic radiation constantly bombarding the earth from outer space, and the contribution, if any, from the monitored facilities and other man-made sources. The Network is intended to measure radiation levels during routine facility operations and to establish background radiation levels used to assess the radiological impact of an unusual condition, such as an accident. This report presents the radiation levels measured around all facilities in the Network for the third quarter of 1995. A complete listing of the site facilities monitored is included. In some instances, two power reactor facilities are monitored by the same set of dosimeters (e.g., Kewaunee and Point Beach). All radiation measurements are made using small, passive detectors called therinoluminescent dosimeters (TLDs), which provide a quantitative measurement of the radiation levels in the area in which they are placed. Each site is monitored by arranging approximately 40 to 50 TLD stations in two concentric rings extending to about five miles from the facility. All TLD stations are outside the site boundary of the facility. A complete description of the program can be found in NUREG-0837, Volume 2, Number 4. A similar description can also be found in the fourth quarter report of each subsequent year. The National Institute of Standards and Technology (formerly the National Bureau of Standards) has performed an independent study of the following characteristics of the NRC dosimetry system; energy response, angular dependence, temperature and humidity sensitivity, fading, light dependence, self-irradiation, and reproducibility.

  18. Development and recent results from the Subaru coronagraphic extreme adaptive optics system

    NASA Astrophysics Data System (ADS)

    Jovanovic, N.; Guyon, O.; Martinache, F.; Clergeon, C.; Singh, G.; Kudo, T.; Newman, K.; Kuhn, J.; Serabyn, E.; Norris, B.; Tuthill, P.; Stewart, P.; Huby, E.; Perrin, G.; Lacour, S.; Vievard, S.; Murakami, N.; Fumika, O.; Minowa, Y.; Hayano, Y.; White, J.; Lai, O.; Marchis, F.; Duchene, G.; Kotani, T.; Woillez, J.

    2014-07-01

    The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument is one of a handful of extreme adaptive optics systems set to come online in 2014. The extreme adaptive optics correction is realized by a combination of precise wavefront sensing via a non-modulated pyramid wavefront sensor and a 2000 element deformable mirror. This system has recently begun on-sky commissioning and was operated in closed loop for several minutes at a time with a loop speed of 800 Hz, on ~150 modes. Further suppression of quasi-static speckles is possible via a process called "speckle nulling" which can create a dark hole in a portion of the frame allowing for an enhancement in contrast, and has been successfully tested on-sky. In addition to the wavefront correction there are a suite of coronagraphs on board to null out the host star which include the phase induced amplitude apodization (PIAA), the vector vortex, 8 octant phase mask, 4 quadrant phase mask and shaped pupil versions which operate in the NIR (y-K bands). The PIAA and vector vortex will allow for high contrast imaging down to an angular separation of 1 λ/D to be reached; a factor of 3 closer in than other extreme AO systems. Making use of the left over visible light not used by the wavefront sensor is VAMPIRES and FIRST. These modules are based on aperture masking interferometry and allow for sub-diffraction limited imaging with moderate contrasts of ~100-1000:1. Both modules have undergone initial testing on-sky and are set to be fully commissioned by the end of 2014.

  19. Effects of Extreme Monsoon Precipitation on River Systems Form And Function, an Early Eocene Perspective

    NASA Astrophysics Data System (ADS)

    Plink-Bjorklund, P.; Birgenheier, L.

    2013-12-01

    Here we document effects of extreme monsoon precipitation on river systems with mountainous drainage basin. We discuss the effects of individual extreme monsoon seasons, as well as long-term changes in Earth surface system's form and function. The dataset spans across 1000 m of stratigraphy across ca 200 km of Paleocene and Early Eocene river deposits. The excessive 3-dimensional outcrops, combined with our new Carbon isotope, ichnological and paleosols record allow reconstruction of long-term river system's evolution during the Paleocene-Eocene Thermal Maximum (PETM) ca 56 million years ago, the transient global warming events during Early Eocene Climate Optimum (EECO) ca 53 to 51.5 million years ago, as well as the effects of highly peaked precipitation events during single monsoon seasons. On the single season scale, the increase in precipitation peakedness causes high discharge flooding events that remove large quantities of sediment from the drainage basin, due to stream erosion and landslide initiation. The initiation of landslides is especially significant, as the drainage basin is of high gradient, the monsoon intensification is accompanied by significant vegetation decline, as the monsoon cycle changes to multi-year droughts interrupted by extreme monsoon precipitation. These large discharge floods laden with sediment cause rapid deposition from high-velocity currents that resemble megaflood deposits in that they are dominated by high-velocity and high deposition rate sedimentary structures and thick simple depositional packages (unit bars). Such high deposition rates cause locally rapid channel bed aggradation and thus increase frequency of channel avulsions and cause catastrophic high-discharge terrestrial flooding events across the river basin. On long time scales, fluvial megafan systems, similar to those, e.g. in the Himalayan foreland, developed across the ca 200 km wide river basin, causing significant sediment aggradation and a landscape with high

  20. Mesosiderite clasts with the most extreme positive europium anomalies among solar system rocks

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.; Rubin, Alan E.; Davis, Andrew M.

    1992-01-01

    Pigeonite-plagioclase gabbros that occur as clasts in mesosiderites (brecciated stony-iron meteorites) show extreme fractionations of the rare-earth elements (REEs) with larger positive europium anomalies than any previously known for igneous rocks from the earth, moon, or meteorite parent bodies and greater depletions of light REEs relative to heavy REEs than known for comparable cumulate gabbros. The REE pattern for merrillite in one of these clasts is depleted in light REEs and has a large positive europium anomaly as a result of metamorphic equilibration with the silicates. The extreme REE ratios exhibited by the mesosiderite clasts demonstrate that multistage igneous processes must have occurred on some asteroids in the early solar system. Melting of the crust by large-scale impacts or electrical induction from an early T-Tauri-phase sun may be responsible for these processes.

  1. Minimizing System Noise Effects For Extreme-Scale Scientific Simulation Through Function Delegation

    SciTech Connect

    Dongarra, Jack J.; Bosilca, George

    2013-06-11

    The primary goal of the Minimizing System Noise Effects For Extreme-Scale Scientific Simulation through Function Delegation project is to eliminate or at best strongly minimize the impact of the noise introduced by the operating system, during large scale parallel applications runs. Collective communication operations are a basic building block for parallel programing models and scientific applications. These operations often dominate execution time of applications and tend to limit their scalability. In order to address this challenge, we evaluated different strategies to adapt the collective communications underlying topologies to the hardware architecture in order to provide increased levels of performance to the parallel applications.

  2. Compact multi-bounce projection system for extreme ultraviolet projection lithography

    DOEpatents

    Hudyma, Russell M.

    2002-01-01

    An optical system compatible with short wavelength (extreme ultraviolet) radiation comprising four optical elements providing five reflective surfaces for projecting a mask image onto a substrate. The five optical surfaces are characterized in order from object to image as concave, convex, concave, convex and concave mirrors. The second and fourth reflective surfaces are part of the same optical element. The optical system is particularly suited for ring field step and scan lithography methods. The invention uses aspheric mirrors to minimize static distortion and balance the static distortion across the ring field width, which effectively minimizes dynamic distortion.

  3. Recovery of Upper Extremity Sensorimotor System Acuity in Baseball Athletes After a Throwing-Fatigue Protocol

    PubMed Central

    Tripp, Brady L; Yochem, Eric M; Uhl, Timothy L

    2007-01-01

    Context: Research indicates that upper extremity fatigue hampers sensorimotor system acuity. However, no investigators have observed recovery of upper extremity acuity after fatigue. Objective: To observe recovery of active position reproduction acuity in overhead throwers after a throwing-fatigue protocol. Design: Single-session, repeated-measures design. Setting: University musculoskeletal laboratory. Patients or Other Participants: Sixteen healthy collegiate baseball players (age = 21.0 ± 1.6 years, height = 175.8 ± 10.2 cm, mass = 82.8 ± 4.3 kg). Intervention(s): Subjects threw a baseball with maximum velocity (every 5 seconds) from a single knee. Every 20 throws, subjects rated their upper extremity exertion on a Borg scale until reporting a level of more than 14. Main Outcome Measure(s): We used an electromagnetic tracking system to measure active multijoint position reproduction acuity at 5 intervals: prefatigue; immediately postfatigue; and after 4, 7, and 10 minutes of recovery. Blindfolded subjects reproduced their arm-cocked and ball-release positions. Dependent variables were 3-dimensional variable errors of scapulothoracic, glenohumeral, elbow, and wrist joints; endpoint (ie, hand) position error represented overall upper extremity acuity. The independent variable was time (measured prefatigue and at 4 postfatigue intervals). Results: Fatigue significantly affected acuity of scapulothoracic, glenohumeral, and elbow joints and endpoint error for both positions (P < .001). Fatigue significantly affected wrist acuity only for ball release (P < .001). For arm-cocked reproduction, each measure of acuity, except that of the glenohumeral joint, recovered by 7 minutes; for ball release, each measure of acuity recovered within 4 minutes (P > .05). Conclusions: The sensorimotor system deficits that we observed after fatigue recovered within 7 minutes in most upper extremity joints. Glenohumeral arm-cocked position reproduction acuity failed to recover within

  4. Modelling Tradeoffs Evolution in Multipurpose Water Systems Operation in Response to Extreme Events

    NASA Astrophysics Data System (ADS)

    Mason, E.; Gazzotti, P.; Amigoni, F.; Giuliani, M.; Castelletti, A.

    2015-12-01

    Multipurpose water resource systems are usually operated on a tradeoff of the operating objectives, which - under steady state climatic and socio-economic boundary conditions - is supposed to ensure a fair and/or efficient balance among the conflicting interests. Extreme variability in the system's drivers might affect operators' risk aversion and force a change in the tradeoff. Properly accounting for these shifts is key to any rigorous retrospective assessment of operators' behavior and the associated system's performance. In this study, we explore how the selection of different optimal tradeoffs among the operating objectives is linked to the variations of the boundary conditions, such as, for example, drifting rainfall season or remarkable changes in crop and energy prices. We argue that tradeoff selection is driven by recent, extreme variations in system performance: underperforming on one of the operating objective target value should push the tradeoff toward the disadvantaged objective. To test this assumption, we developed a rational procedure to simulate the operators' tradeoff selection process. We map the selection onto a multi lateral negotiation process, where different multiple, virtual agents optimize different operating objectives. The agents periodically negotiate a compromise on the operating policy. The agent's rigidity in each negotiation round is determined by the recent system performances according to the specific objective it represents. The negotiation follows a set-based egocentric monotonic concession protocol: at each negotiation step an agent incrementally adds some options to the set of its acceptable compromises and (possibly) accepts lower and lower satisfying policies until an agreement is achieved. We apply this reiterated negotiation framework on the regulated Lake Como, Italy, simulating the lake dam operation and its recurrent updates over the last 50 years. The operation aims to balance shoreline flood prevention and irrigation

  5. Summertime Extremes in the Arctic Climate System: Understanding the 2012 Extreme Greenland Melt in the Context of the 1889 Episode

    NASA Astrophysics Data System (ADS)

    Neff, W. D.; Compo, G. P.; Webb, R. S.

    2013-12-01

    The last melting of the high Greenland ice sheet prior to 2012 occurred in 1889 and prior to that a number of times during the Medieval Warm Anomaly. In the case of the 2012 episode, key factors in the summer melt episode were a combination of 1) Central North American drought andheat wave, 2) Amplification of a polar trough-ridge pattern, 3) A positive excursion of the Atlantic Multi-Decadal Oscillation (AMO), and 4) Advection of warm moist air northward along the west coast of Greenland and thence over the ice sheet as an elevated thin liquid cloud layer. In both episodes, transport over the western Atlantic to Greenland in the form of 'Atmospheric Rivers,' thin filaments of high water vapor air, are observed in both the 20CR (which uses only historic global surface pressure measurements and sea-surface temperatures back to 1871) and satellite imagery. In the 2012 case, air mass changes associated with these transport events over Greenland were marked by rapid changes in observed isotope time series (Personal communications, Masson-Delmotte and Steen-Hansen). In this presentation, we use the 2012 episode to 'calibrate' the 20CR as a tool to examine past extreme events involving mid-latitude and northern ice sheet interaction. Of particular importance is determining the limits on 20CR-derived back-trajectory analyses: While the 2012 back-trajectories from modern reanalyses are fairly convincing in documenting the various transport paths, in 1889 the interpretation is complicated by the interplay of the propagation of ridge-trough patterns versus material transport coupled with the relatively coarse resolution of the 20CR. What we found in 1889 were two potential melt-inducing episodes in July. These episodes have many of the key factors seen in 2012: a positive AMO, moisture transport along the U.S. east coast, and warm-air transport from the west with some trajectories originating in the drought-stricken Dakota Territory.

  6. Perfusion Assessment with the SPY System after Arterial Venous Reversal for Upper Extremity Ischemia

    PubMed Central

    2014-01-01

    Background: The timing and pattern of reperfusion following arterial- venous reversal (AVR) in patients with terminal ischemia of an upper extremity is not well understood. Methods: The current case series describes the timing and pattern of reperfusion observed in patients with terminal upper extremity ischemia who underwent AVR and repeated postoperative indocyanine green (ICG) angiography between 2004 and 2009. For all included patients, the SPY Near-Infrared Perfusion Assessment System permitted visualization of ICG-labeled blood flow for 60-second sampling periods at scheduled postoperative time points; outflow and rate and amplitude of inflow were objectively quantified with SPY-Q Analysis Toolkit image analysis software. Results: The series comprised 6 male patients (mean age, 46 years) who presented with upper extremity ischemia related to hypothenar hammer syndrome (n = 2), embolism with patent foramen ovale (n = 2), atherosclerosis (n = 1), and avulsion amputation of the thumb (n = 1); the patient with the avulsion amputation was diagnosed with thromboangiitis obliterans at the time of replantation. AVR was successful in all 6 patients. In 5 of 6 patients, ICG angiography and SPY-based visualization/quantification showed that venous outflow and arterial inflow gradually normalized (versus unaffected digits) between postoperative days (PODs) 0 and 3 and was maintained at long-term follow-up (≥3 months); for the patient who underwent thumb replantation, perfusion normalized between POD 3 and month 5 follow-up. Conclusions: AVR effectively reestablished blood flow in patients with terminal upper extremity ischemia. ICG angiography with SPY technology revealed that, in most cases, kinetic curves, timing, and patterns of perfusion gradually normalized over several PODs. PMID:25426368

  7. Dynamic damage evolution in aluminum as a model system for understanding FCC materials in extreme conditions

    NASA Astrophysics Data System (ADS)

    Sanchez, Nathaniel Jonathon

    Materials play a key role in many emerging technologies. Future technologies in the energy and defense sectors will place huge demands on material performance with respect to stress, strain, temperature, and pressure. These applications require that the response of materials on dynamic (microsecond) time scales be predictable and controllable. Hence, the goal of this research project was to study the extreme environment of shock loaded damage evolution in aluminum as a model system for understanding dynamic response of FCC metals in these environments. Phase one utilized plate impact experiments to study the influence of spatial effects (in the form of microstructural defect distributions) on the dynamic damage evolution process. Samples were soft recovered for shot analysis and comparison to real time laser velocimetry. Results revealed that the length scale of defects controls the failure mechanisms of the microstructure; suggesting defect density and the spatial distribution of defects are critical factors in the deformation process in extreme environments. Phase two studied the influence of kinetic effects (in the form of dynamic tensile loading rate) to reveal time dependence on the dynamic deformation process. Results concluded damage nucleation and growth rates are highly time dependent and can be overdriven as higher tensile loading rates result in extremely short time durations. It was shown that laser velocimetry provides an adequate means for understanding the dynamic damage evolution process when soft recovery of the sample is unavailable. This was shown by comparing laser velocimetry results with data obtained from optical analysis on recovered specimens. The methodology here provides a means to systematically study materials of interest in extreme conditions and provides a pathway for obtaining the relevant physics needed for model development leading to a predictive capability.

  8. Overview and Update of the North America Drought Monitor and North America Climate Extremes Monitoring System

    NASA Astrophysics Data System (ADS)

    Heim, R. R.

    2006-12-01

    The North America Drought Monitor (NADM) is a joint operational drought monitoring activity between scientists and other specialists in the United States, Mexico, and Canada. Like all weather phenomena, drought occurs irrespective of political and international boundaries. The monthly map and narrative product created by this first-of-its-kind effort provides an integrated continental-scale drought assessment tool for decision-makers in all three countries involved in drought monitoring, drought mitigation, and related climate services. The product is prepared by a rotating primary author who utilizes drought indicators which are computed using standard methodologies for stations across the continent, plus national drought monitoring products and feedback from local experts in each of the three countries. The participants include, within the United States: the NOAA National Climatic Data Center, NOAA Climate Prediction Center, USDA Joint Agricultural Weather Facility, and National Drought Mitigation Center; within Mexico: Servicio Meteorologico Nacional/Comision Nacional del Agua; and within Canada: Agriculture and Agrifood Canada and the Meteorological Service of Canada. The NADM is part of a North America Climate Extremes Monitoring (NACEM) system which will monitor and assess climate extremes across the continent. Several climate indicators are currently computed from station daily data to measure (in addition to drought) heavy precipitation, heat waves, and cold waves. Future efforts will add indicators to monitor storm severity and severe weather, including the creation of a North America Climate Extremes Index (NACEI) patterned after the U.S. Climate Extremes Index (USCEI). This presentation will review the history of the NADM/NACEM effort, the data utilized, the indicators computed, and the product preparation and peer review process.

  9. Self-Adaptive System based on Field Programmable Gate Array for Extreme Temperature Electronics

    NASA Technical Reports Server (NTRS)

    Keymeulen, Didier; Zebulum, Ricardo; Rajeshuni, Ramesham; Stoica, Adrian; Katkoori, Srinivas; Graves, Sharon; Novak, Frank; Antill, Charles

    2006-01-01

    In this work, we report the implementation of a self-adaptive system using a field programmable gate array (FPGA) and data converters. The self-adaptive system can autonomously recover the lost functionality of a reconfigurable analog array (RAA) integrated circuit (IC) [3]. Both the RAA IC and the self-adaptive system are operating in extreme temperatures (from 120 C down to -180 C). The RAA IC consists of reconfigurable analog blocks interconnected by several switches and programmable by bias voltages. It implements filters/amplifiers with bandwidth up to 20 MHz. The self-adaptive system controls the RAA IC and is realized on Commercial-Off-The-Shelf (COTS) parts. It implements a basic compensation algorithm that corrects a RAA IC in less than a few milliseconds. Experimental results for the cold temperature environment (down to -180 C) demonstrate the feasibility of this approach.

  10. NRC TLD Direct Radiation Monitoring Network: Volume 15, No. 1. Progress report, January--March 1995

    SciTech Connect

    Struckmeyer, R.

    1995-05-01

    This report provides the status and results of the NRC Thermoluminescent Dosimeter (TLD) Direct Radiation Monitoring Network. It presents the radiation levels measured in the vicinity of NRC licensed facilities throughout the country for the first quarter of 1995.

  11. NRC TLD direct radiation monitoring network: Progress report, April--June 1997. Volume 17, Number 2

    SciTech Connect

    Struckmeyer, R.

    1997-09-01

    This report provides the status and results of the NRC Thermoluminescent Dosimeter (TLD) Direct Radiation Monitoring Network. It presents the radiation levels measured in the vicinity of NRC licensed facilities throughout the country for the second quarter of 1997.

  12. Luminescence emission of natural fluorite and synthetic CaF2:Mn (TLD-400)

    NASA Astrophysics Data System (ADS)

    Topaksu, Mustafa; Correcher, Virgilio; Garcia-Guinea, Javier

    2016-02-01

    The luminescence properties of natural white fluorite indicate that it could be employed as radiation dosimeter similarly to synthetic CaF2:Mn (TLD-400). The cathodoluminescence emission of the natural sample (two maxima) meanwhile TLD-400 (one peak) exhibits a different behaviour associated with the chemical composition. The mineral sample displays (i) a significant UV-blue emission associated with different structural defects (negligible in the synthetic sample) and (ii) a shift of the green emission to higher wavelengths respect to the TLD-400. The green induced TL emission also shows significant differences in intensity (higher in TLD-400) and sensitivity. Both samples display a complex induced green TL glow curve that could not be analysed assuming the model based on the discrete trap distribution. The Tm-Tstop method indicates the presence of close overlapping groups of components linked probably to a continuum in the trap distribution rather than a single trapping level.

  13. NRC TLD Direct Radiation Monitoring Network. Progress report, July--September 1993: Volume 13, No. 3

    SciTech Connect

    Struckmeyer, R.

    1993-11-01

    This report provides the status and results of the NRC Thermoluminescent Dosimeter (TLD) Direct Radiation Monitoring Network. It presents the radiation levels measured in the vicinity of NRC licensed facilities throughout the country for the third quarter of 1993.

  14. Dosimetry quality assurance in Martin Marietta Energy Systems` centralized external dosimetry system

    SciTech Connect

    Souleyrette, M.L.

    1992-10-23

    External dosimetry needs at the four Martin Marietta Energy Systems facilities are served by Energy Systems Centralized External Dosimetry System (CEDS). The CEDS is a four plant program with four dosimeter distribution centers and two dosimeter processing centers. Each plant has its own distribution center, while processing centers are located at ORNL and the Y-12 Plant. The program has been granted accreditation by the Department of Energy Laboratory Accreditation Program (DOELAP). The CEDS is a TLD based system which is responsible for whole-body beta-gamma, neutron, and extremity monitoring. Beta-gamma monitoring is performed using the Harshaw/Solon Technologies model 8805 dosimeter. Effective October 1, 1992 the standard silver mylar has been replaced with an Avery mylar foil blackened on the underside with ink. This was done in an effort to reduce the number of light induced suspect readings. At this time we have little operational experience with the new blackened mylars-The CEDS neutron dosimeter is the Harshaw model 8806B. This card/holder configuration contains two TLD-600/TLD-700 chip pairs; one pair is located beneath a cadmium filter and one pair is located beneath a plastic filter. In routine personnel monitoring the CEDS neutron dosimeter is always paired with a CEDS beta-gamma dosimeter.The CEDS extremity dosimeter is composed of a Harshaw thin TLD-700 dosiclip placed inside a Teledyne RB-4 finger sachet. The finger sachet provides approximately 7 mg/cm{sup 2} filtration over the chip. A teflon ring surrounds the dosiclip to help prevent tearing of the vinyl sachet.

  15. Dosimetry quality assurance in Martin Marietta Energy Systems' centralized external dosimetry system

    SciTech Connect

    Souleyrette, M.L.

    1992-10-23

    External dosimetry needs at the four Martin Marietta Energy Systems facilities are served by Energy Systems Centralized External Dosimetry System (CEDS). The CEDS is a four plant program with four dosimeter distribution centers and two dosimeter processing centers. Each plant has its own distribution center, while processing centers are located at ORNL and the Y-12 Plant. The program has been granted accreditation by the Department of Energy Laboratory Accreditation Program (DOELAP). The CEDS is a TLD based system which is responsible for whole-body beta-gamma, neutron, and extremity monitoring. Beta-gamma monitoring is performed using the Harshaw/Solon Technologies model 8805 dosimeter. Effective October 1, 1992 the standard silver mylar has been replaced with an Avery mylar foil blackened on the underside with ink. This was done in an effort to reduce the number of light induced suspect readings. At this time we have little operational experience with the new blackened mylars-The CEDS neutron dosimeter is the Harshaw model 8806B. This card/holder configuration contains two TLD-600/TLD-700 chip pairs; one pair is located beneath a cadmium filter and one pair is located beneath a plastic filter. In routine personnel monitoring the CEDS neutron dosimeter is always paired with a CEDS beta-gamma dosimeter.The CEDS extremity dosimeter is composed of a Harshaw thin TLD-700 dosiclip placed inside a Teledyne RB-4 finger sachet. The finger sachet provides approximately 7 mg/cm[sup 2] filtration over the chip. A teflon ring surrounds the dosiclip to help prevent tearing of the vinyl sachet.

  16. Modeling of the Human - Operator in a Complex System Functioning Under Extreme Conditions

    NASA Astrophysics Data System (ADS)

    Getzov, Peter; Hubenova, Zoia; Yordanov, Dimitar; Popov, Wiliam

    2013-12-01

    Problems, related to the explication of sophisticated control systems of objects, operating under extreme conditions, have been examined and the impact of the effectiveness of the operator's activity on the systems as a whole. The necessity of creation of complex simulation models, reflecting operator's activity, is discussed. Organizational and technical system of an unmanned aviation complex is described as a sophisticated ergatic system. Computer realization of main subsystems of algorithmic system of the man as a controlling system is implemented and specialized software for data processing and analysis is developed. An original computer model of a Man as a tracking system has been implemented. Model of unmanned complex for operators training and formation of a mental model in emergency situation, implemented in "matlab-simulink" environment, has been synthesized. As a unit of the control loop, the pilot (operator) is simplified viewed as an autocontrol system consisting of three main interconnected subsystems: sensitive organs (perception sensors); central nervous system; executive organs (muscles of the arms, legs, back). Theoretical-data model of prediction the level of operator's information load in ergatic systems is proposed. It allows the assessment and prediction of the effectiveness of a real working operator. Simulation model of operator's activity in takeoff based on the Petri nets has been synthesized.

  17. Resonance Raman Spectroscopy of Extreme Nanowires and Other 1D Systems

    PubMed Central

    Smith, David C.; Spencer, Joseph H.; Sloan, Jeremy; McDonnell, Liam P.; Trewhitt, Harrison; Kashtiban, Reza J.; Faulques, Eric

    2016-01-01

    This paper briefly describes how nanowires with diameters corresponding to 1 to 5 atoms can be produced by melting a range of inorganic solids in the presence of carbon nanotubes. These nanowires are extreme in the sense that they are the limit of miniaturization of nanowires and their behavior is not always a simple extrapolation of the behavior of larger nanowires as their diameter decreases. The paper then describes the methods required to obtain Raman spectra from extreme nanowires and the fact that due to the van Hove singularities that 1D systems exhibit in their optical density of states, that determining the correct choice of photon excitation energy is critical. It describes the techniques required to determine the photon energy dependence of the resonances observed in Raman spectroscopy of 1D systems and in particular how to obtain measurements of Raman cross-sections with better than 8% noise and measure the variation in the resonance as a function of sample temperature. The paper describes the importance of ensuring that the Raman scattering is linearly proportional to the intensity of the laser excitation intensity. It also describes how to use the polarization dependence of the Raman scattering to separate Raman scattering of the encapsulated 1D systems from those of other extraneous components in any sample. PMID:27168195

  18. [Design of optical system for solar extreme-ultraviolet imaging spectrometer].

    PubMed

    Liu, Zhuang; Gong, Yan

    2012-03-01

    Hyper-spectral imaging observation of the sun in the EUV region is an important method of research for solar's upper transition region, corona and plasma's physical property. Based on the application objective of solar extreme ultraviolet imaging spectrometer (SEUIS), combined with the current states of domestic and foreign extreme ultraviolet imaging spectrometer, a few of parameters for SEUIS design were drew up in the present paper. The advantages and disadvantages of all kinds of optical configurations were discussed,and the configuration of combination of telescope and spectrometer was chosen. The available main components were also described, off-axis parabolic mirror was chosen for telescope, and a high density uniform-line-space toroidal grating for dispersion device. The optical system which satisfies the performance parameters was designed. The design process, detailed parameters and results were presented in the end. The working wavelength of the optics system is 17.0-21.0 nm, the field of view is 1 228" x 1 024", the spatial resolution is 0.8 arc sec x pixel(-1), the spectral resolution is about 0.00198 nm x pixel(-1), and the total length of system is about 2.8 m. PMID:22582664

  19. Resonance Raman Spectroscopy of Extreme Nanowires and Other 1D Systems.

    PubMed

    Smith, David C; Spencer, Joseph H; Sloan, Jeremy; McDonnell, Liam P; Trewhitt, Harrison; Kashtiban, Reza J; Faulques, Eric

    2016-01-01

    This paper briefly describes how nanowires with diameters corresponding to 1 to 5 atoms can be produced by melting a range of inorganic solids in the presence of carbon nanotubes. These nanowires are extreme in the sense that they are the limit of miniaturization of nanowires and their behavior is not always a simple extrapolation of the behavior of larger nanowires as their diameter decreases. The paper then describes the methods required to obtain Raman spectra from extreme nanowires and the fact that due to the van Hove singularities that 1D systems exhibit in their optical density of states, that determining the correct choice of photon excitation energy is critical. It describes the techniques required to determine the photon energy dependence of the resonances observed in Raman spectroscopy of 1D systems and in particular how to obtain measurements of Raman cross-sections with better than 8% noise and measure the variation in the resonance as a function of sample temperature. The paper describes the importance of ensuring that the Raman scattering is linearly proportional to the intensity of the laser excitation intensity. It also describes how to use the polarization dependence of the Raman scattering to separate Raman scattering of the encapsulated 1D systems from those of other extraneous components in any sample. PMID:27168195

  20. Treatment of Diabetic Foot Ulcers through Systemic Effects of Extremely Low Frequency Electromagnetic Fields

    NASA Astrophysics Data System (ADS)

    Trejo-Núñez, A. D.; Pérez-Chávez, F.; García-Sánchez, C.; Serrano-Luna, G.; Cañendo-Dorantes, L.

    2008-08-01

    This study was designed to, investigate the healing effects of extremely low frequency electromagnetic fields (ELF-EMF) on diabetic foot ulcers and test two different exposure systems aimed at reducing the ELF-EMF exposure time of patients. In the first system the ELF-EMF were applied to the arm where only 3% of the total blood volume/min circulates at any given time. In the second system the ELF-EMF were applied to the thorax where more than 100% of the total blood volume/minute circulates at any given time. Twenty-six diabetic patients, with superficial neuropathic ulcers unresponsive to medical treatment were included in this preliminary report. In the first group (17 patients), the arm was exposed two hours twice a week to a extremely low frequency electromagnetic field of 0.45-0.9 mTrms, 120 Hz generated inside a solenoid coil of 10.1 cm by 20.5 cm long. In the second group the thorax of 7 patients was exposed 25 minutes twice a week to an electromagnetic field of 0.4-0.85 mTrms, 120 Hz generated in the center of a squared quasi-Helmholtz coil 52 cm by side. One patient was assigned to a placebo configuration of each exposure system with identical appearance as the active equipment but without magnetic field. Patients with deep ulcers, infected ulcers, cancer, or auto-immune disease were excluded. These preliminary results showed that the two exposure systems accelerate the healing process of neuropathic ulcers. Complete healing of the ulcer had a median duration of 90 days in both exposure systems. Therefore thorax exposure where more blood is exposed to ELF-EMF per unit of time was able to reduce 4.8 times the patient treatment time. In those patients assigned to the placebo equipment no healing effects were observed. This study will continue with a parallel, double blind placebo controlled protocol.

  1. How extreme are extremes?

    NASA Astrophysics Data System (ADS)

    Cucchi, Marco; Petitta, Marcello; Calmanti, Sandro

    2016-04-01

    High temperatures have an impact on the energy balance of any living organism and on the operational capabilities of critical infrastructures. Heat-wave indicators have been mainly developed with the aim of capturing the potential impacts on specific sectors (agriculture, health, wildfires, transport, power generation and distribution). However, the ability to capture the occurrence of extreme temperature events is an essential property of a multi-hazard extreme climate indicator. Aim of this study is to develop a standardized heat-wave indicator, that can be combined with other indices in order to describe multiple hazards in a single indicator. The proposed approach can be used in order to have a quantified indicator of the strenght of a certain extreme. As a matter of fact, extremes are usually distributed in exponential or exponential-exponential functions and it is difficult to quickly asses how strong was an extreme events considering only its magnitude. The proposed approach simplify the quantitative and qualitative communication of extreme magnitude

  2. DISCOVERY OF A BRIGHT, EXTREMELY LOW MASS WHITE DWARF IN A CLOSE DOUBLE DEGENERATE SYSTEM

    SciTech Connect

    Vennes, S.; Kawka, A.; Nemeth, P.; Thorstensen, J. R.; Skinner, J. N.; Pigulski, A.; Steslicki, M.; Kolaczkowski, Z.; Srodka, P.

    2011-08-10

    We report the discovery of a bright (V {approx} 13.7), extremely low mass white dwarf in a close double degenerate system. We originally selected GALEX J171708.5+675712 for spectroscopic follow-up among a group of white dwarf candidates in an ultraviolet-optical reduced proper-motion diagram. The new white dwarf has a mass of 0.18 M{sub sun} and is the primary component of a close double degenerate system (P = 0.246137 days, K{sub 1} = 288 km s{sup -1}) comprising a fainter white dwarf secondary with M{sub 2} {approx} 0.9 M{sub sun}. Light curves phased with the orbital ephemeris show evidence of relativistic beaming and weaker ellipsoidal variations. The light curves also reveal secondary eclipses (depth {approx}8 mmag) while the primary eclipses appear partially compensated by the secondary gravitational deflection and are below detection limits. Photospheric abundance measurements show a nearly solar composition of Si, Ca, and Fe (0.1-1 sun), while the normal kinematics suggest a relatively recent formation history. Close binary evolutionary scenarios suggest that extremely low mass white dwarfs form via a common-envelope phase and possible Roche lobe overflow.

  3. Can we colonize the solar system? Human biology and survival in the extreme space environment.

    PubMed

    Launius, Roger D

    2010-09-01

    Throughout the history of the space age the dominant vision for the future has been great spaceships plying the solar system, and perhaps beyond, moving living beings from one planet to another. Spacesuited astronauts would carry out exploration, colonization, and settlement as part of a relentlessly forward looking movement of humanity beyond Earth. As time has progressed this image has not changed appreciably even as the full magnitude of the challenges it represents have become more and more apparent. This essay explores the issues associated with the human movement beyond Earth and raises questions about whether humanity will ever be able to survive in the extreme environment of space and the other bodies of the solar system. This paper deals with important historical episodes as well as wider conceptual issues about life in space. Two models of expansion beyond Earth are discussed: (1) the movement of microbes and other types of life on Earth that can survive the space environment and (2) the modification of humans into cyborgs for greater capability to survive in the extreme environments encountered beyond this planet. PMID:20692704

  4. Complex networks identify spatial patterns of extreme rainfall of the South American monsoon system

    NASA Astrophysics Data System (ADS)

    Boers, Niklas; Bokkhagen, Bodo; Marwan, Norbert; Kurths, Jürgen; Marengo, Jose

    2014-05-01

    In this study, we investigate the spatial characteristics of extreme rainfall synchronicity of the South American Monsoon System (SAMS) by means of Complex Networks. We first show how this approach leads to the identification of linkages between large-scale atmospheric conditions and natural hazards occurring at the earth's surface. Thereafter, we exemplify how our methodology can be used to compare different datasets and to test the performance of climate models. In recent years, complex networks have attracted great attention for analyzing the spatial characteristics of interrelations of various time series. Outstanding examples in this context are functional brain networks as well as so-called climate networks. In most approaches, the basic idea is to represent time series at different locations by network nodes, which will be connected by network links if the corresponding time series behave similar. Information on the spatial characteristics of these similarities can be inferred by network measures quantifying different aspects of the networks' topology. By combining several network measures and interpreting them in a climatic context, we investigate climatic linkages and classify the spatial characteristics of extreme rainfall synchronicity. Although our approach is based on only one variable (high spatiotemporal resolution rainfall), it reveals the most important features of the SAMS, such as the main moisture pathways, areas with frequent development of Mesoscale Convective Systems, and the major convergence zones. We will show that these features are only partially reproduced by reanalysis and (regional and global) climate model data.

  5. SAXO, the eXtreme Adaptive Optics System of SPHERE: overview and calibration procedure

    NASA Astrophysics Data System (ADS)

    Sauvage, J.-F.; Fusco, T.; Petit, C.; Meimon, S.; Fedrigo, E.; Suarez Valles, M.; Kasper, M.; Hubin, N.; Beuzit, J.-L.; Charton, J.; Costille, A.; Rabou, P., .; Mouillet, D.; Baudoz, P.; Buey, T.; Sevin, A.; Wildi, F.; Dohlen, K.

    2010-07-01

    The direct imaging of exoplanet is a challenging goal of todays astronomy. The light transmitted by exoplanet atmosphere is of a great interest as it may witness for life sign. SPHERE is a second generation instrument for the VLT, dedicated to exoplanet imaging, detection, and characterisation. SPHERE is a global project of an European consortium of 11 institutes from 5 countries. We present here the state of the art of the AIT of the Adaptive Optics part of the instrument. In addition we present fine calibration procedures dedicated to eXtreme Adaptive Optics systems. First we emphasized on vibration and turbulence identification for optimization of the control law. Then, we describe a procedure able to measure and compensate for NCPA with a coronagraphic system.

  6. Lazy Checkpointing : Exploiting Temporal Locality in Failures to Mitigate Checkpointing Overheads on Extreme-Scale Systems

    SciTech Connect

    Tiwari, Devesh; Gupta, Saurabh; Vazhkudai, Sudharshan S

    2014-01-01

    Continuing increase in the computational power of supercomputers has enabled large-scale scientific applications in the areas of astrophysics, fusion, climate and combustion to run larger and longer-running simulations, facilitating deeper scientific insights. However, these long-running simulations are often interrupted by multiple system failures. Therefore, these applications rely on ``checkpointing'' as a resilience mechanism to store application state to permanent storage and recover from failures. \\\\ \\indent Unfortunately, checkpointing incurs excessive I/O overhead on supercomputers due to large size of checkpoints, resulting in a sub-optimal performance and resource utilization. In this paper, we devise novel mechanisms to show how checkpointing overhead can be mitigated significantly by exploiting the temporal characteristics of system failures. We provide new insights and detailed quantitative understanding of the checkpointing overheads and trade-offs on large-scale machines. Our prototype implementation shows the viability of our approach on extreme-scale machines.

  7. Climate engineering of vegetated land for hot extremes mitigation: An Earth system model sensitivity study

    NASA Astrophysics Data System (ADS)

    Wilhelm, Micah; Davin, Edouard L.; Seneviratne, Sonia I.

    2015-04-01

    Various climate engineering schemes have been proposed as a way to curb anthropogenic climate change. Land climate engineering schemes aiming to reduce the amount of solar radiation absorbed at the surface by changes in land surface albedo have been considered in a limited number of investigations. However, global studies on this topic have generally focused on the impacts on mean climate rather than extremes. Here we present the results of a series of transient global climate engineering sensitivity experiments performed with the Community Earth System Model over the time period 1950-2100 under historical and Representative Concentration Pathway 8.5 scenarios. Four sets of experiments are performed in which the surface albedo over snow-free vegetated grid points is increased respectively by 0.05, 0.10, 0.15, and 0.20. The simulations show a preferential cooling of hot extremes relative to mean temperatures throughout the Northern midlatitudes during boreal summer under the late twentieth century conditions. Two main mechanisms drive this response: On the one hand, a stronger efficacy of the albedo-induced radiative forcing on days with high incoming shortwave radiation and, on the other hand, enhanced soil moisture-induced evaporative cooling during the warmest days relative to the control simulation due to accumulated soil moisture storage and reduced drying. The latter effect is dominant in summer in midlatitude regions and also implies a reduction of summer drought conditions. It thus constitutes another important benefit of surface albedo modifications in reducing climate change impacts. The simulated response for the end of the 21st century conditions is of the same sign as that for the end of the twentieth century conditions but indicates an increasing absolute impact of land surface albedo increases in reducing mean and extreme temperatures under enhanced greenhouse gas forcing.

  8. Comparison of dosimeter response: ionization chamber, TLD, and Gafchromic EBT2 film in 3D-CRT, IMRT, and SBRT techniques for lung cancer

    NASA Astrophysics Data System (ADS)

    Fitriandini, A.; Wibowo, W. E.; Pawiro, S. A.

    2016-03-01

    This research was conducted by measuring point dose in the target area (lungs), heart, and spine using four dosimeters (PTW N30013, Exradin A16, TLD, and the Gafchromic EBT2 film). The measurement was performed in CIRS 002LFC thorax phantom. The main objective of this study was to compare the dosimetry of those different systems. Dose measurements performed only in a single fraction of irradiation. The measurements result shown that TLD has the least accuracy and precision. As the effect of volume averaging, ionization chamber reaches the discrepancy value up to -13.30% in the target area. EBT2 film has discrepancy value of <1% in the 3D-CRT and IMRT techniques. This dosimeter is proposed to be an appropriate alternative dosimeter to be used at point dose verification.

  9. Understanding and Exploiting Spatial Properties of System Failures on Extreme-Scale HPC Systems

    SciTech Connect

    Tiwari, Devesh; Rogers, James H; Maxwell, Don E

    2015-01-01

    As we approach exascale, the scientific simulations are expected to experience more interruptions due to increased system failures. Designing better HPC resilience techniques requires understanding the key characteristics of system failures on these systems. While temporal properties of system failures on HPC systems have been well-investigated, there is limited understanding about the spatial characteristics of system failures and its impact on the resilience mechanisms. Therefore, we examine the spatial characteristics and behavior of system failures. We investigate the interaction between spatial and temporal characteristics of failures and its implications for system operations and resilience mechanisms on large-scale HPC systems. We show that system failures have spatial locality at different granularity in the system; study impact of different failure-types; and investigate the correlation among different failure-types. Finally, we propose a novel scheme that exploits the spatial locality in failures to improve application and system performance. Our evaluation shows that the proposed scheme significantly improves the system performance in a dynamic and production-level HPC system.

  10. Adaption to extreme rainfall with open urban drainage system: an integrated hydrological cost-benefit analysis.

    PubMed

    Zhou, Qianqian; Panduro, Toke Emil; Thorsen, Bo Jellesmark; Arnbjerg-Nielsen, Karsten

    2013-03-01

    This paper presents a cross-disciplinary framework for assessment of climate change adaptation to increased precipitation extremes considering pluvial flood risk as well as additional environmental services provided by some of the adaptation options. The ability of adaptation alternatives to cope with extreme rainfalls is evaluated using a quantitative flood risk approach based on urban inundation modeling and socio-economic analysis of corresponding costs and benefits. A hedonic valuation model is applied to capture the local economic gains or losses from more water bodies in green areas. The framework was applied to the northern part of the city of Aarhus, Denmark. We investigated four adaptation strategies that encompassed laissez-faire, larger sewer pipes, local infiltration units, and open drainage system in the urban green structure. We found that when taking into account environmental amenity effects, an integration of open drainage basins in urban recreational areas is likely the best adaptation strategy, followed by pipe enlargement and local infiltration strategies. All three were improvements compared to the fourth strategy of no measures taken. PMID:23334752

  11. Adaption to Extreme Rainfall with Open Urban Drainage System: An Integrated Hydrological Cost-Benefit Analysis

    NASA Astrophysics Data System (ADS)

    Zhou, Qianqian; Panduro, Toke Emil; Thorsen, Bo Jellesmark; Arnbjerg-Nielsen, Karsten

    2013-03-01

    This paper presents a cross-disciplinary framework for assessment of climate change adaptation to increased precipitation extremes considering pluvial flood risk as well as additional environmental services provided by some of the adaptation options. The ability of adaptation alternatives to cope with extreme rainfalls is evaluated using a quantitative flood risk approach based on urban inundation modeling and socio-economic analysis of corresponding costs and benefits. A hedonic valuation model is applied to capture the local economic gains or losses from more water bodies in green areas. The framework was applied to the northern part of the city of Aarhus, Denmark. We investigated four adaptation strategies that encompassed laissez-faire, larger sewer pipes, local infiltration units, and open drainage system in the urban green structure. We found that when taking into account environmental amenity effects, an integration of open drainage basins in urban recreational areas is likely the best adaptation strategy, followed by pipe enlargement and local infiltration strategies. All three were improvements compared to the fourth strategy of no measures taken.

  12. Low-pressure systems and extreme precipitation in central India: sensitivity to temperature changes

    NASA Astrophysics Data System (ADS)

    Sørland, Silje Lund; Sorteberg, Asgeir

    2015-10-01

    Extreme rainfall events in the central Indian region are often related to the passage of synoptic scale monsoon low-pressure systems (LPS). This study uses the surrogate climate change method on ten monsoon LPS cases connected to observed extreme rainfall events, to investigate how sensitive the precipitation and runoff are to an idealized warmer and moister atmosphere. The ten cases are simulated with three different initial and lateral boundary conditions: the unperturbed control run, and two sets of perturbed runs where the atmospheric temperature is increased uniformly throughout the atmosphere, the specific humidity increased according to Clausius Clapeyron's relation, but the large-scale flow is unchanged. The difference between the control and perturbed simulations are mainly due to the imposed warming and feedback influencing the synoptic flow. The mean precipitation change with warming in the central Indian region is 18-20 %/K, with largest changes at the end of the LPS tracks. The LPS in the warmer runs are bringing more moisture further inland that is released as precipitation. In the perturbed runs the precipitation rate is increasing at all percentiles, and there is more frequent rainfall with very heavy intensities. This leads to a shift in which category that contributes most to the total precipitation: more of the precipitation is coming from the category with very heavy intensities. The runoff changes are similar to the precipitation changes, except the response in intensity of very heavy runoff, which is around twice the change in intensity of very heavy precipitation.

  13. Absolute intensity calibration of the Wendelstein 7-X high efficiency extreme ultraviolet overview spectrometer system

    NASA Astrophysics Data System (ADS)

    Greiche, Albert; Biel, Wolfgang; Marchuk, Oleksandr; Burhenn, Rainer

    2008-09-01

    The new high effiency extreme ultraviolet overview spectrometer (HEXOS) system for the stellarator Wendelstein 7-X is now mounted for testing and adjustment at the tokamak experiment for technology oriented research (TEXTOR). One part of the testing phase was the intensity calibration of the two double spectrometers which in total cover a spectral range from 2.5 to 160.0 nm with overlap. This work presents the current intensity calibration curves for HEXOS and describes the method of calibration. The calibration was implemented with calibrated lines of a hollow cathode light source and the branching ratio technique. The hollow cathode light source provides calibrated lines from 16 up to 147 nm. We could extend the calibrated region in the spectrometers down to 2.8 nm by using the branching line pairs emitted by an uncalibrated pinch extreme ultraviolet light source as well as emission lines from boron and carbon in TEXTOR plasmas. In total HEXOS is calibrated from 2.8 up to 147 nm, which covers most of the observable wavelength region. The approximate density of carbon in the range of the minor radius from 18 to 35 cm in a TEXTOR plasma determined by simulating calibrated vacuum ultraviolet emission lines with a transport code was 5.5×1017 m-3 which corresponds to a local carbon concentration of 2%.

  14. Low-pressure systems and extreme precipitation in central India: sensitivity to temperature changes

    NASA Astrophysics Data System (ADS)

    Sørland, Silje Lund; Sorteberg, Asgeir

    2016-07-01

    Extreme rainfall events in the central Indian region are often related to the passage of synoptic scale monsoon low-pressure systems (LPS). This study uses the surrogate climate change method on ten monsoon LPS cases connected to observed extreme rainfall events, to investigate how sensitive the precipitation and runoff are to an idealized warmer and moister atmosphere. The ten cases are simulated with three different initial and lateral boundary conditions: the unperturbed control run, and two sets of perturbed runs where the atmospheric temperature is increased uniformly throughout the atmosphere, the specific humidity increased according to Clausius Clapeyron's relation, but the large-scale flow is unchanged. The difference between the control and perturbed simulations are mainly due to the imposed warming and feedback influencing the synoptic flow. The mean precipitation change with warming in the central Indian region is 18-20 %/K, with largest changes at the end of the LPS tracks. The LPS in the warmer runs are bringing more moisture further inland that is released as precipitation. In the perturbed runs the precipitation rate is increasing at all percentiles, and there is more frequent rainfall with very heavy intensities. This leads to a shift in which category that contributes most to the total precipitation: more of the precipitation is coming from the category with very heavy intensities. The runoff changes are similar to the precipitation changes, except the response in intensity of very heavy runoff, which is around twice the change in intensity of very heavy precipitation.

  15. SU-E-I-09: Application of LiF:Mg,Cu (TLD-100H) Dosimeters for in Diagnostic Radiology

    SciTech Connect

    Sina, S; Zeinali, B; Karimipourfard, M; Lotfalizadeh, F; Sadeghi, M; Faghihi, R

    2014-06-01

    Purpose: Accurate dosimetery is very essential in diagnostic radiology. The goal of this study is to verify the application of LiF:Mg,Cu,P (TLD100H) in obtaining the Entrance skin dose (ESD) of patients undergoing diagnostic radiology. The results of dosimetry performed by TLD-100H, were compared with those obtained by TLD100, which is a common dosimeter in diagnostic radiology. Methods: In this study the ESD values were measured using two types of Thermoluminescence dosimeters (TLD-100, and TLD-100H) for 16 patients undergoing diagnostic radiology (lumbar spine imaging). The ESD values were also obtained by putting the two types of TLDs at the surface of Rando phantom for different imaging techniques and different views (AP, and lateral). The TLD chips were annealed with a standard procedure, and the ECC values for each TLD was obtained by exposing the chips to equal amount of radiation. Each time three TLD chips were covered by thin dark plastic covers, and were put at the surface of the phantom or the patient. The average reading of the three chips was used for obtaining the dose. Results: The results show a close agreement between the dose measuered by the two dosimeters.According to the results of this study, the TLD-100H dosimeters have higher sensitivities (i.e.signal(nc)/dose) than TLD-100.The ESD values varied between 2.71 mGy and 26.29 mGy with the average of 11.89 mGy for TLD-100, and between 2.55 mGy and 27.41 mGy with the average of 12.32 mGy for measurements. Conclusion: The TLD-100H dosimeters are suggested as effective dosimeters for dosimetry in low dose fields because of their higher sensitivities.

  16. Response of TLD-100 in mixed fields of photons and electrons

    SciTech Connect

    Lawless, Michael J.; Junell, Stephanie; Hammer, Cliff; DeWerd, Larry A.

    2013-01-15

    Purpose: Thermoluminescent dosimeters (TLDs) are routinely used for dosimetric measurements of high energy photon and electron fields. However, TLD response in combined fields of photon and electron beam qualities has not been characterized. This work investigates the response of TLD-100 (LiF:Mg,Ti) to sequential irradiation by high-energy photon and electron beam qualities. Methods: TLDs were irradiated to a known dose by a linear accelerator with a 6 MV photon beam, a 6 MeV electron beam, and a NIST-traceable {sup 60}Co beam. TLDs were also irradiated in a mixed field of the 6 MeV electron beam and the 6 MV photon beam. The average TLD response per unit dose of the TLDs for each linac beam quality was normalized to the average response per unit dose of the TLDs irradiated by the {sup 60}Co beam. Irradiations were performed in water and in a Virtual Water Trade-Mark-Sign phantom. The 6 MV photon beam and 6 MeV electron beam were used to create dose calibration curves relating TLD response to absorbed dose to water, which were applied to the TLDs irradiated in the mixed field. Results: TLD relative response per unit dose in the mixed field was less sensitive than the relative response in the photon field and more sensitive than the relative response in the electron field. Application of the photon dose calibration curve to the TLDs irradiated in a mixed field resulted in an underestimation of the delivered dose, while application of the electron dose calibration curve resulted in an overestimation of the dose. Conclusions: The relative response of TLD-100 in mixed fields fell between the relative response in the photon-only and electron-only fields. TLD-100 dosimetry of mixed fields must account for this intermediate response to minimize the estimation errors associated with calibration factors obtained from a single beam quality.

  17. A musculoskeletal model of the upper extremity for use in the development of neuroprosthetic systems

    PubMed Central

    Blana, Dimitra; Hincapie, Juan G.; Chadwick, Edward K.; Kirsch, Robert F.

    2008-01-01

    Upper extremity neuroprostheses use functional electrical stimulation (FES) to restore arm motor function to individuals with cervical level spinal cord injury. For the design and testing of these systems, a biomechanical model of the shoulder and elbow has been developed, to be used as a substitute for the human arm. It can be used to design and evaluate specific implementations of FES systems, as well as FES controllers. The model can be customized to simulate a variety of pathological conditions. For example, by adjusting the maximum force the muscles can produce, the model can be used to simulate an individual with tetraplegia and to explore the effects of FES of different muscle sets. The model comprises six bones, five joints, nine degrees of freedom, and 29 shoulder and arm muscles. It was developed using commercial, graphics-based modeling and simulation packages that are easily accessible to other researchers and can be readily interfaced to other analysis packages. It can be used for both forward-dynamic (inputs: muscle activation and external load; outputs:motions) and inverse-dynamic (inputs: motions and external load; outputs: muscle activation) simulations. Our model was verified by comparing the model-calculated muscle activations to electromyographic signals recorded from shoulder and arm muscles of five subjects. As an example of its application to neuroprosthesis design, the model was used to demonstrate the importance of rotator cuff muscle stimulation when aiming to restore humeral elevation. It is concluded that this model is a useful tool in the development and implementation of upper extremity neuroprosthetic systems. PMID:18420213

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    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.

  19. A method to minimise the fading effects of LiF:Mg,Ti (TLD-600 and TLD-700) using a pre-heat technique.

    PubMed

    Lee, YoungJu; Won, Yuho; Kang, Kidoo

    2015-04-01

    Passive integrating dosemeters [thermoluminescent dosimeter (TLD) and optically stimulated luminescence (OSL)] are the only legally permitted individual dosemeters for occupational external radiation exposure monitoring in Korea. Also its maximum issuing cycle does not exceed 3 months, and the Korean regulations require personal dosemeters for official assessment of external radiation exposure to be issued by an approved or rather an accredited dosimetry service according to ISO/IEC 17025. KHNP (Korea Hydro & Nuclear Power, LTD), a unique operating company of nuclear power plants (NPPs) in Korea, currently has a plan to extend a TLD issuing cycle from 1 to 3 months under the authors' fading error criteria, ±10%. The authors have performed a feasibility study that minimises post-irradiation fading effects within their maximum reading cycle employing pre-heating technique. They repeatedly performed irradiation/reading a bare TLD chip to determine optimum pre-heating conditions by analysing each glow curve. The optimum reading conditions within the maximum reading cycle of 3 months were decided: a pre-heating temperature of 165°C, a pre-heating time of 9 s, a heating rate of 25°C s(-1), a reading temperature of 300°C and an acquisition time of 10 s. The fading result of TLD-600 and TLD-700 carried by newly developed time temperature profile (TTP) showed a much smaller fading effect than that of current TTP. The result showed that the fading error due to a developed TTP resulted in a ∼5% signal loss, whereas a current TTP caused a ∼15% loss. The authors also carried out a legal performance test on newly developed TTP to confirm its possibility as an official dosemeter. The legal performance tests that applied the developed TTP satisfied the criteria for all the test categories. PMID:25301971

  20. Optimization of an on-board imaging system for extremely rapid radiation therapy

    SciTech Connect

    Cherry Kemmerling, Erica M.; Wu, Meng Yang, He; Fahrig, Rebecca; Maxim, Peter G.; Loo, Billy W.

    2015-11-15

    Purpose: Next-generation extremely rapid radiation therapy systems could mitigate the need for motion management, improve patient comfort during the treatment, and increase patient throughput for cost effectiveness. Such systems require an on-board imaging system that is competitively priced, fast, and of sufficiently high quality to allow good registration between the image taken on the day of treatment and the image taken the day of treatment planning. In this study, three different detectors for a custom on-board CT system were investigated to select the best design for integration with an extremely rapid radiation therapy system. Methods: Three different CT detectors are proposed: low-resolution (all 4 × 4 mm pixels), medium-resolution (a combination of 4 × 4 mm pixels and 2 × 2 mm pixels), and high-resolution (all 1 × 1 mm pixels). An in-house program was used to generate projection images of a numerical anthropomorphic phantom and to reconstruct the projections into CT datasets, henceforth called “realistic” images. Scatter was calculated using a separate Monte Carlo simulation, and the model included an antiscatter grid and bowtie filter. Diagnostic-quality images of the phantom were generated to represent the patient scan at the time of treatment planning. Commercial deformable registration software was used to register the diagnostic-quality scan to images produced by the various on-board detector configurations. The deformation fields were compared against a “gold standard” deformation field generated by registering initial and deformed images of the numerical phantoms that were used to make the diagnostic and treatment-day images. Registrations of on-board imaging system data were judged by the amount their deformation fields differed from the corresponding gold standard deformation fields—the smaller the difference, the better the system. To evaluate the registrations, the pointwise distance between gold standard and realistic registration

  1. Invisible marking system by extreme ultraviolet radiation: the new frontier for anti-counterfeiting tags

    NASA Astrophysics Data System (ADS)

    Di Lazzaro, P.; Bollanti, S.; Flora, F.; Mezi, L.; Murra, D.; Torre, A.; Bonfigli, F.; Montereali, R. M.; Vincenti, M. A.

    2016-07-01

    We present a marking technology which uses extreme ultraviolet radiation to write invisible patterns on tags based on alkali fluoride thin films. The shape of the pattern is pre-determined by a mask (in the case of contact lithography) or by a suitable mirror (projection lithography). Tags marked using this method offer a much better protection against fakes than currently available anti-counterfeiting techniques. The complexity and cost of this technology can be tailored to the value of the good to be protected, leaving, on the other hand, the specific reading technique straightforward. So far, we have exploited our invisible marking to tag artworks, identity cards, electrical components, and containers of radioactive wastes. Advantages and limits of this technology are discussed in comparison with the anti-counterfeiting systems available in the market.

  2. Impact of an absorbent silver-eluting dressing system on lower extremity revascularization wound complications.

    PubMed

    Childress, Beverly B; Berceli, Scott A; Nelson, Peter R; Lee, W Anthony; Ozaki, C Keith

    2007-09-01

    Surgical wounds for lower extremity revascularization are prone to infection and dehiscence. Acticoat Absorbent, an antimicrobial dressing, offers sustained release of ionic silver. We hypothesized that immediate application of Acticoat as a postoperative dressing would reduce wound complications in patients undergoing leg revascularization. All infrainguinal revascularization cases involving leg incisions at a single Veterans Administration Medical Center were identified from July 1, 2002, to September 30, 2005. The control group received conventional dressings, while the treatment group received an Acticoat dressing. Wound complication rates were captured via National Surgical Quality Improvement Program data. Patient characteristics and procedure distributions were similar between groups. The wound complication rate fell 64% with utilization of the Acticoat-based dressing (control 14% [17/118], treatment 5% [7/130]; P = 0.016). An Acticoat-based dressing system offers a potentially useful, cost-effective adjunct to reduce open surgical leg revascularization wound complications. PMID:17521872

  3. The evolution of energy-transducing systems. Studies with an extremely halophilic archaebacterium

    NASA Technical Reports Server (NTRS)

    Stan-Lotter, Helga

    1991-01-01

    The halobacterial ATPase was labeled with C-14-dicyclohexylcarbodiimide and subunit 2 of the enzyme was prepared by electroelution. Subunit 2 was cleaved by several chemical and enzymatic procedures for further preparation of peptides. Immunoreactions (Western blotting) of halobacterial membranes were performed with an antiserum against subunit A of the vacuolar ATPase from Neurospora crassa. A 85 K band (subunit 1) from the membranes of H saccharovorum and from two halobacterial isolates, which were isolated from Permian salt sediments, reacted strongly with the antiserum. The ATPase from the latter isolates resembled the ATPase from H saccharovorum, but had a higher content of acidic amino acids. If it can be verified that the age of the bacterial isolates is in the same range as when deposition of salt occurred, an extremely interesting system for the study of evolutionary questions would be available, since the salt-embedded bacteria presumably did not undergo mutational and selectional events.

  4. Extreme Ultraviolet Explorer observations of the RS Canum Venaticorum systems AR Lacertae and II Pegasi

    NASA Technical Reports Server (NTRS)

    Petterer, R. J.; Vedder, P. W.; Jelinsky, P.; Brown, A.; Bowyer, S.

    1993-01-01

    We report observations of two RS CVn systems, II Peg and AR Lac, which were calibration targets during the in-orbit checkout phase of the Extreme Ultraviolet Explorer (EUVE). We have determined count rates, and, based on these count rates, preliminary emission measure analyses have been done. The Lexan/boron band count rates were 0.0849 +/- 0.0023 counts/s for AR Lac and 0.218 +/- 0.031 counts/s for II Peg during its quiescent state. Temperatures and emission measures derived from the EUVE data are consistent with previously published values. We also report a flare seen during the II Peg observations which has characteristics similar to previously observed flares on II Peg. During the flare the Lexan/boron count rate increased by at least a factor of 2.5, and the minimum total duration was about 34,000 s (about 9.4 hr).

  5. Cellular and molecular pathways of extremely-low-frequency electromagnetic field interactions with living systems

    NASA Astrophysics Data System (ADS)

    Tenforde, T. S.

    1992-06-01

    There is growing evidence that environmental electric and magnetic fields in the extremely-low-frequency (ELF) band below 300 Hz can influence biological functions by mechanisms that are only poorly understood at the present time. The primary objectives of this paper are to review the physical properties of ELF fields, their interactions with living systems at the tissue, cellular, and subcellular levels, and the key role of cell membranes in the transduction of signals from imposed ELF fields. Topics of discussion include signal-to-noise ratios for single cells and cell aggregates, resonance phenomena involving a combination of static and ELF magnetic fields, and the possible influence of ELF fields on molecular signaling pathways that involve membrane receptors and cytoplasmic second messengers.

  6. Cellular and molecular pathways of extremely-low-frequency electromagnetic field interactions with living systems

    SciTech Connect

    Tenforde, T.S.

    1992-06-01

    There is growing evidence that environmental electric and magnetic fields in the extremely-low-frequency (ELF) band below 300 Hz can influence biological functions by mechanisms that are only poorly understood at the present time. The primary objectives of this paper are to review the physical properties of ELF fields, their interactions with living systems at the tissue, cellular, and subcellular levels, and the key role of cell membranes ;in the transduction of signals from imposed ELF fields. Topics of discussion include signal-to-noise ratios for single cells and cell aggregates, resonance phenomena involving a combination of static and ELF magnetic fields, and the possible influence of ELF fields on molecular signaling pathways that involve membrane receptors and cytoplasmic second messengers.

  7. ELF (Extremely Low Frequency) communications systems ecological monitoring program: Wetland studies

    NASA Astrophysics Data System (ADS)

    Guntenspergen, Glenn; Keough, Janet; Stearns, Forest; Wikum, Douglas

    1989-11-01

    The results and conclusions are presented of in situ studies designed to monitor for possible effects on wetland flora from exposure to electromagnetic (EM) fields produced by the U.S. Navy's Extremely Low Frequency (ELF) Communications System. The studies examined for possible effects to herbs, shrubs, and trees growing on peat bogs near the Navy's Wisconsin Transmitting Facility (WTF). Plant characteristics studied included foliar cation content, stomatal resistance, and rate of foliar decomposition. Eleven bogs similar in plant community structure and interstitial water chemistry were used as study sites. Treatment sites were located immediately adjacent to the WTF antenna or its grounds, and experienced EM field intensities at least two orders of magnitude greater than control sites.

  8. Creation of a neo-aortoiliac system from lower extremity deep and superficial veins.

    PubMed Central

    Clagett, G P; Bowers, B L; Lopez-Viego, M A; Rossi, M B; Valentine, R J; Myers, S I; Chervu, A

    1993-01-01

    OBJECTIVE: This study evaluated the morbidity, mortality, and intermediate term follow-up of patients undergoing replacement of their aortoiliac-femoral systems with lower extremity deep and superficial veins. SUMMARY BACKGROUND DATA: The most commonly used treatment for aortic prosthetic infection is ectopic bypass and removal of the prosthesis. The overall mortality rate with this approach is approximately 20%, with an amputation rate of 10% to 14%. Other limitations include thrombosis of the ectopic bypass leading to limb loss, reinfection of the ectopic bypass, and aortic stump blowout. Dissatisfaction with this approach has led the authors to develop the following. METHODS: A neo-aortoiliac system (NAIS) was fashioned from lower extremity deep veins (DV), greater saphenous veins (GSV), or both in patients with infected aortobifemoral prosthesis (n = 17) and other complex aortic problems (n = 3). Removal of infected prosthetic material, harvest of vein, and creation of NAIS was performed as a single-staged procedure. RESULTS: The in-hospital mortality and amputation rates were 10% each. The mean (+/- standard deviation [SD]) operative time was 6.5 +/- 1.8 hours and the blood transfusion requirement was 4 +/- 3 units. Four patients experienced postoperative gastrointestinal complications with peritonitis and sepsis; NAIS vein graft resisted infection and remained intact. The mean follow-up time was 22.5 +/- 16 months. NAISs constructed from GSVs were prone to the development of focal stenoses requiring intervention or diffuse neointimal hyperplasia leading to occlusion. In contrast, all NAISs from larger caliber DVs have remained widely patent. The failure rate of GSV NAISs was 64%, compared to 0% for DV NAISs (p = 0.006). Despite the high failure rate in patients with GSV NAISs, none has required amputation. In patients who had DVs harvested for NAIS reconstruction, limb edema and other signs of venous hypertension have been minimal. CONCLUSION: NAIS

  9. Woven Thermal Protection System Based Heat-shield for Extreme Entry Environments Technology (HEEET)

    NASA Technical Reports Server (NTRS)

    Ellerby, Donald; Venkatapathy, Ethiraj; Stackpoole, Margaret; Chinnapongse, Ronald; Munk, Michelle; Dillman, Robert; Feldman, Jay; Prabhu, Dinesh; Beerman, Adam

    2013-01-01

    NASA's future robotic missions utilizing an entry system into Venus and the outer planets, namely, Saturn, Uranus, Neptune, result in extremely high entry conditions that exceed the capabilities of state of the art low to mid density ablators such as PICA or Avcoat. Therefore mission planners typically assume the use of a fully dense carbon phenolic heat shield similar to what was flown on Pioneer Venus and Galileo. Carbon phenolic is a robust TPS material however its high density and relatively high thermal conductivity constrain mission planners to steep entries, with high heat fluxes and pressures and short entry durations, in order for CP to be feasible from a mass perspective. The high entry conditions pose challenges for certification in existing ground based test facilities and the longer-term sustainability of CP will continue to pose challenges. In 2012 the Game Changing Development Program (GCDP) in NASA's Space Technology Mission Directorate funded NASA ARC to investigate the feasibility of a Woven Thermal Protection System (WTPS) to meet the needs of NASA's most challenging entry missions. This project was highly successful demonstrating that a Woven TPS solution compares favorably to CP in performance in simulated reentry environments and provides the opportunity to manufacture graded materials that should result in overall reduced mass solutions and enable a much broader set of missions than does CP. Building off the success of the WTPS project GCDP has funded a follow on project to further mature and scale up the WTPS concept for insertion into future NASA robotic missions. The matured WTPS will address the CP concerns associated with ground based test limitations and sustainability. This presentation will briefly discuss results from the WTPS Project and the plans for WTPS maturation into a heat-shield for extreme entry environment.

  10. Woven Thermal Protection System Based Heat-shield for Extreme Entry Environments Technology (HEEET)

    NASA Technical Reports Server (NTRS)

    Chinnapongse, Ronald; Ellerbe, Donald; Stackpoole, Maragaret; Venkatapathy, Ethiraj; Beerman, Adam; Feldman, Jay; Peterson Keith; Prabhu, Dinesh; Dillman, Robert; Munk, Michelle

    2013-01-01

    NASA's future robotic missions utilizing an entry system into Venus and the outer planets, namely, Saturn, Uranus, Neptune, result in extremely severe entry conditions that exceed the capabilities of state of the art low to mid density ablators such as PICA or Avcoat. Therefore mission planners typically assume the use of a fully dense carbon phenolic heat shield similar to what was flown on Pioneer Venus and Galileo. Carbon phenolic (CP) is a robust TPS material however its high density and relatively high thermal conductivity constrain mission planners to steep entries, with high heat fluxes and pressures and short entry durations, in order for CP to be feasible from a mass perspective. The high entry conditions pose challenges for certification in existing ground based test facilities and the longer-­-term sustainability of CP will continue to pose challenges. In 2012 the Game Changing Development Program (GCDP) in NASA's Space Technology Mission Directorate funded NASA ARC to investigate the feasibility of a Woven Thermal Protection System (WTPS) to meet the needs of NASA's most challenging entry missions. This project was highly successful demonstrating that a Woven TPS solution compares favorably to CP in performance in simulated reentry environments and provides the opportunity to manufacture graded materials that should result in overall reduced mass solutions and enable a much broader set of missions than does CP. Building off the success of the WTPS project GCDP has funded a follow on project to further mature and scale up the WTPS concept for insertion into future NASA robotic missions. The matured WTPS will address the CP concerns associated with ground based test limitations and sustainability. This presentation will briefly discuss results from the WTPS Project and the plans for WTPS maturation into a heat-­-shield for extreme entry environment.

  11. Manaus city Flow Warning system and extreme events monitoring in the Amazon Basin

    NASA Astrophysics Data System (ADS)

    Santos, A. L. M. R.; Oliveira, D.; Oliveira, M. A.; Moreira, D.; Maciel, J. S. C.

    2012-04-01

    The Amazon basin is the biggest watershed in the world, in the center of this basin, there is a city called Manaus, with population next to 2 million habitants. Manaus city is bounded by Negro River; one of the main rivers in Amazon, this river has its level checked by Fluvial Station in the Manaus harbor, which has a range of 100 years of hydrological data records. The hydrological cycle in the region next to Manaus has certain regularity, its common variety is considered of 7 months of rising river, in other words, the fluvial quotes rising and 5 months of falling (ebb). Although, the water level variation in Manaus Harbor, from its draft to flow can achieve the variation up to 16 meters of water level height, this difference can affect all the Amazon region, happening impacts such as the interference of regional agriculture and fluvial transportation, besides the economic activities in the harbor and local population welfare, arising from extreme events. Considering the relevance of prediction and accompanying of flows and drafts, the Geologic Survey of Brazil implemented, since 1989, a warning system to these extreme events. This paper focused to demonstrate the a warning system implemented from equations based on the Manaus Harbor quotes, since Negro River has a regular hydrological cycle, thus, it is possible to predict the highest quotes in the hydrological year, in advance till 75 days with accurate prediction, in a gap of 45 to 15 days before the flow. This paper presents, also, the biggest events occurred in a hundred years of records collected by Manaus Harbor, as example, the draft happened in December 2010 and the flow in June 2009, as well demonstrating the values and impacts in the Amazon region.

  12. ASAS J083241+2332.4: A New Extreme Low Mass Ratio Overcontact Binary System

    NASA Astrophysics Data System (ADS)

    Sriram, K.; Malu, S.; Choi, C. S.; Vivekananda Rao, P.

    2016-03-01

    We present the R- and V-band CCD photometry and Hα line studies of an overcontact binary ASAS J083241+2332.4. The light curves exhibit totality along with a trace of the O’Connell effect. The photometric solution indicates that this system falls into the category of extreme low-mass ratio overcontact binaries with a mass ratio, q ˜ 0.06. Although a trace of the O’ Connell effect is observed, constancy of the Hα line along various phases suggest that a relatively higher magnetic activity is needed for it to show a prominent fill-in effect. The study of O-C variations reveals that the period of the binary shows a secular increase at the rate of dP/dt ˜ 0.0765 s years-1, which is superimposed by a low, but significant, sinusoidal modulation with a period of ˜8.25 years. Assuming that the sinusoidal variation is due to the presence of a third body, orbital elements have been derived. There exist three other similar systems, SX Crv, V857 Her, and E53, which have extremely low mass ratios and we conclude that ASAS J083241+2332.4 resembles SX Crv in many respects. Theoretical studies indicate that at a critical mass ratio range, qcritical = 0.07-0.09, overcontact binaries should merge and form a fast rotating star, but it has been suggested that qcritical can continue to fall up to 0.05 depending on the primary's mass and structure. Moreover, the obtained fill-out factors (50%-70%) indicate that mass loss is considerable and hydrodynamical simulations advocate that mass loss from L2 is mandatory for a successful merging process. Comprehensively, the results indicate that ASAS J083241+2332.4 is at a stage of merger. The pivotal role played by the subtle nature of the derived mass ratio in forming a rapidly rotating star has been discussed.

  13. Wafer and reticle positioning system for the Extreme Ultraviolet Lithography Engineering Test Stand

    SciTech Connect

    WRONOSKY,JOHN B.; SMITH,TONY G.; CRAIG,MARCUS J.; STURGIS,BEVERLY R.; DARNOLD,JOEL R.; WERLING,DAVID K.; KINCY,MARK A.; TICHENOR,DANIEL A.; WILLIAMS,MARK E.; BISCHOFF,PAUL

    2000-01-27

    This paper is an overview of the wafer and reticle positioning system of the Extreme Ultraviolet Lithography (EUVL) Engineering Test Stand (ETS). EUVL represents one of the most promising technologies for supporting the integrated circuit (IC) industry's lithography needs for critical features below 100nm. EUVL research and development includes development of capabilities for demonstrating key EUV technologies. The ETS is under development at the EUV Virtual National Laboratory, to demonstrate EUV full-field imaging and provide data that supports production-tool development. The stages and their associated metrology operated in a vacuum environment and must meet stringent outgassing specifications. A tight tolerance is placed on the stage tracking performance to minimize image distortion and provide high position repeatability. The wafer must track the reticle with less than {+-}3nm of position error and jitter must not exceed 10nm rms. To meet these performance requirements, magnetically levitated positioning stages utilizing a system of sophisticated control electronics will be used. System modeling and experimentation have contributed to the development of the positioning system and results indicate that desired ETS performance is achievable.

  14. SU-E-J-101: Retroactive Calculation of TLD and Film Dose in Anthropomorphic Phantom as Assessment of Updated TPS Performance

    SciTech Connect

    Alkhatib, H; Oves, S

    2014-06-01

    Purpose: To demonstrate a quick and comprehensive method verifying the accuracy of the updated dose model by recalculating dose distribution in an anthropomorphic phantom with a new version of the TPS and comparing the results to measured values. Methods: CT images and IMRT plan of an RPC anthropomorphic head phantom, previously calculated by Pinnacle 9.0, was re-computed using Pinnacle 9.2 and 9.6. The dosimeters within the phantom include four TLD capsules representing a primary PTV, two TLD capsules representing a secondary PTV, and two TLD capsules representing an organ at risk. Also included were three sheets of Gafchromic film. Performance of the updated TPS version was assessed by recalculating point doses and dose profiles corresponding to TLD and film position respectively and then comparing the results to reported values by the RPC. Results: Comparing calculated doses to reported measured doses from the RPC yielded an average disagreement of 1.48%, 2.04% and 2.10% for versions 9.0, 9.2, 9.6 respectively. Computed doses points all meet the RPC's passing criteria with the exception of the point representing the superior organ at risk in version 9.6. However, qualitative analysis of the recalculated dose profiles showed improved agreement with those of the RPC, especially in the penumbra region. Conclusion: This work has demonstrated the calculation results of Pinnacle 9.2 and 9.6 vs 9.0 version. Additionally, this study illustrates a method for the user to gain confidence upgrade to a newer version of the treatment planning system.

  15. Study of the improvement of TLD cards for personal neutron dosimetry

    NASA Astrophysics Data System (ADS)

    Rabie, N.; Hassan, G. M.; El-Sersy, A. R.; Ezzat, M.

    2010-04-01

    In this work, personal thermoluminescence dosimeter (TLD) cards type of GN-6770 (holder type 8806) from Harshaw were used for personal neutron dosimetry. The response of the dosimeters has been determined in terms of the personal absorbed dose and personal dose equivalent for different neutron energy components, based on the recommendations of ICRP-60 and ICRU-49. Neutron irradiation was performed using a 5 mCi Am-Be neutron source. The TLD reader, type Harshaw 6600, was installed and calibrated for accurate neutron doses equivalent to gamma-ray doses. It was found that fast neutron doses measured by TLD (badges or cards) are in agreement with those measured by neutron TE (tissue equivalent gas) ionization chambers and neutron monitors. Thermal neutron doses measured by TLD cards were overestimated when compared with those measured by neutron monitors. Additional Cd was used to reduce thermal neutron doses to be in agreement with actual thermal doses. Other configurations for TLD crystals are also suggested for accurate thermal neutron dose measurements.

  16. Personnel dose equivalent monitoring at SLAC using lithium-fluoride TLD's (thermoluminescent dosimeters)

    SciTech Connect

    Jenkins, T.M.; Busick, D.D.

    1987-03-01

    TLD's replaced film badges in the early 1970's for all dose equivalent monitoring, both neutron and photon, and for all locations at SLAC. The photon TLD's, composed of Li-7 loaded teflon discs, are calibrated using conventional gamma-ray sources; i.e., Co-60, Cs-137, etc. For these TLD's a nominal value of 1 nC/mrem is used, and is independent of source energy for 100 keV to 3 MeV. Since measured dose equivalents at SLAC are only a small fraction of the allowable levels, it was not deemed necessary to develop neutron dosimeters which would measure dose equivalent accurately for all possible neutron spectra. Today, wallet TLD's, composed of pairs of Li-7 and Li-6 discs, are used, with the Li-6 measuring only thermal neutrons; i.e., they aren't moderated in any way to make them sensitive to neutrons with energies greater than thermal. The assumption is made that there is a correlation between thermal neutron fluences and fast neutron fluences around the research area where almost all neutron doses (exclusive of sealed sources) are received. The calibration factor for these Li-6 TLD's is 1 nC/mrem of fast neutrons. The method of determining the validity of this calibration is the subject of this note. 4 refs., 9 figs., 1 tab.

  17. Susceptibility of South Korea to hydrologic extremes affecting the global food system

    NASA Astrophysics Data System (ADS)

    Puma, M. J.; Chon, S. Y.

    2015-12-01

    Food security in South Korea is closely linked to trade in the global food system. The country's production of major grains declined from 5.8 million metric tons (mmt) in 1998 to 4.8 mmt in 2014, which coincided with a shift in grain self sufficiency from 43% down to 24% over this same period. Many factors led to these changes, including reductions in domestic agricultural land, governmental policies supporting industry over agriculture, and a push towards trade liberalization. South Korea's self sufficiency is now one of the lowest among Organisation for Economic Co-operation and Development (OECD) countries, leaving it vulnerable to disruptions in the global food system. Here we explore this vulnerability by assessing how global trade disruptions would affect Korea's food security. We impose historical extreme drought and flood events that would possibly affect today's major food producing regions concurrently. Next we compute food supply deficits in South Korea that might result from these events. Our analyses provide a framework for formulating domestic food policies to enhance South Korea's food security in the increasingly fragile global food system.

  18. Precision and accuracy of 3D lower extremity residua measurement systems

    NASA Astrophysics Data System (ADS)

    Commean, Paul K.; Smith, Kirk E.; Vannier, Michael W.; Hildebolt, Charles F.; Pilgram, Thomas K.

    1996-04-01

    Accurate and reproducible geometric measurement of lower extremity residua is required for custom prosthetic socket design. We compared spiral x-ray computed tomography (SXCT) and 3D optical surface scanning (OSS) with caliper measurements and evaluated the precision and accuracy of each system. Spiral volumetric CT scanned surface and subsurface information was used to make external and internal measurements, and finite element models (FEMs). SXCT and OSS were used to measure lower limb residuum geometry of 13 below knee (BK) adult amputees. Six markers were placed on each subject's BK residuum and corresponding plaster casts and distance measurements were taken to determine precision and accuracy for each system. Solid models were created from spiral CT scan data sets with the prosthesis in situ under different loads using p-version finite element analysis (FEA). Tissue properties of the residuum were estimated iteratively and compared with values taken from the biomechanics literature. The OSS and SXCT measurements were precise within 1% in vivo and 0.5% on plaster casts, and accuracy was within 3.5% in vivo and 1% on plaster casts compared with caliper measures. Three-dimensional optical surface and SXCT imaging systems are feasible for capturing the comprehensive 3D surface geometry of BK residua, and provide distance measurements statistically equivalent to calipers. In addition, SXCT can readily distinguish internal soft tissue and bony structure of the residuum. FEM can be applied to determine tissue material properties interactively using inverse methods.

  19. Hydrogeomorphic response to extreme rainfall in headwater systems: Flash floods and debris flows

    NASA Astrophysics Data System (ADS)

    Borga, Marco; Stoffel, Markus; Marchi, Lorenzo; Marra, Francesco; Jakob, Matthias

    2014-10-01

    Flash floods and debris flows develop at space and time scales that conventional observation systems for rainfall, streamflow and sediment discharge are not able to monitor. Consequently, the atmospheric, hydrological and geomorphic controls on these hydrogeomorphic processes are poorly understood, leading to highly uncertain warning and risk management. On the other hand, remote sensing of precipitation and numerical weather predictions have become the basis of several flood forecasting systems, enabling increasingly accurate detection of hazardous events. The objective of this paper is to provide a review on current European and international research on early warning systems for flash floods and debris flows. We expand upon these themes by identifying: (a) the state of the art; (b) knowledge gaps; and (c) suggested research directions to advance warning capabilities for extreme hydrogeomorphic processes. We also suggest three areas in which advancements in science will have immediate and important practical consequence, namely development of rainfall estimation and nowcasting schemes suited to the specific space-time scales, consolidating physical, engineering and social datasets of flash floods and debris-flows, integration of methods for multiple hydrogeomorphic hazard warning.

  20. [Transport systems for carbonate in the extremely natronophilic cyanobacterium Euhalothece sp].

    PubMed

    Mikhodiuk, O S; Zavarzin, G A; Ivanovskiĭ, R N

    2008-01-01

    The effect of carbonate concentration, pH of the medium, and illumination intensity on the major physiological characteristics (growth rate and the intensities of CO2 assimilation and oxygen photoproduction) of the natronophilic cyanobacterium Euhalothece sp. Z-M001 have been studied. It was established that the investigated microorganism has at least two transport systems (TS) for CO2, which differ in both the pH optimum and substrate affinity: TS I has a pH, 9.4-9.5 and a K(S) 0.5 of 13-17 mM, whereas TS II has a pH(opt) 9.9-10.2 and a K(S) 0.5 of 600-800 mM. The substrate affinity of these transport systems is several orders of magnitude lower than the substrate affinity of the transport systems of freshwater cyanobacteria. It is suggested that they are unique for extremely alkaliphilic cyanobacteria and reflect their adaptation to the seasonal cycles of the lake hydrochemistry. PMID:18825972

  1. The oceanic response of the Turkish Straits System to an extreme drop in atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Book, Jeffrey W.; Jarosz, Ewa; Chiggiato, Jacopo; Beşiktepe, Åükrü

    2014-06-01

    Moorings across all four entry/exit sections of the Dardanelles Strait and the Bosphorus Strait simultaneously measured the response of the Turkish Straits System to the passage of a severe cyclonic storm that included an atmospheric pressure drop of more than 30 mbar in less than 48 h. The bottom pressure response at the Aegean Sea side of the Dardanelles Strait was consistent with an inverted barometer response, but the response at the other sections did not follow an inverted barometer, leading to a large bottom pressure gradient through the Turkish Straits System. Upper-layer flow toward the Aegean Sea was reversed by the storm and flow toward the Black Sea was greatly enhanced. Bottom pressure across the Sea of Marmara peaked 6 h after the passage of the storm's minimum pressure. The response on the Dardanelles side was a combination of sea elevation and pycnocline depth rise, and the response on the Bosphorus side was an even greater sea elevation rise and a drop in pycnocline depth. The peak in bottom pressure in the Sea of Marmara was followed by another reverse in the flow through the Dardanelles Strait as flow was then directed away from the Sea of Marmara in both straits. A simple conceptual model without wind is able to explain fluctuations in bottom pressure in the Sea of Marmara to a 0.89-0.96 level of correlation. This stresses the importance of atmospheric pressure dynamics in driving the mass flux of the Turkish Strait System for extreme storms.

  2. Suppression of extreme orbital evolution in triple systems with short-range forces

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Muñoz, Diego J.; Lai, Dong

    2015-02-01

    The Lidov-Kozai (LK) mechanism plays an important role in the secular evolution of many hierarchical triple systems. The standard LK mechanism consists of large-amplitude oscillations in eccentricity and inclination of a binary subject to the quadrupole potential from an outer perturber. Recent work has shown that when the octupole terms are included in the potential, the inner binary can reach more extreme eccentricities as well as undergo orientation flips. It is known that pericentre precessions due to short-range effects, such as General Relativity and tidal and rotational distortions, can limit the growth of eccentricity and even suppress standard (quadrupolar) LK oscillations, but their effect on the octupole-level LK mechanism has not been fully explored. In this paper, we systematically study how these short-range forces affect the extreme orbital behaviour found in octupole LK cycles. In general, the influence of the octupole potential is confined to a range of initial mutual inclinations itot centred around 90° (when the inner binary mass ratio is ≪1), with this range expanding with increasing octupole strength. We find that, while the short-range forces do not change the width and location of this `window of influence', they impose a strict upper limit on the maximum achievable eccentricity. This limiting eccentricity can be calculated analytically, and its value holds even for strong octupole potential and for the general case of three comparable masses. Short-range forces also affect orbital flips, progressively reducing the range of itot within which flips are possible as the intensity of these forces increases.

  3. A computer aided diagnosis system for thyroid disease using extreme learning machine.

    PubMed

    Li, Li-Na; Ouyang, Ji-Hong; Chen, Hui-Ling; Liu, Da-You

    2012-10-01

    In this paper, we present an effective and efficient computer aided diagnosis (CAD) system based on principle component analysis (PCA) and extreme learning machine (ELM) to assist the task of thyroid disease diagnosis. The CAD system is comprised of three stages. Focusing on dimension reduction, the first stage applies PCA to construct the most discriminative new feature set. After then, the system switches to the second stage whose target is model construction. ELM classifier is explored to train an optimal predictive model whose parameters are optimized. As we known, the number of hidden neurons has an important role in the performance of ELM, so we propose an experimental method to hunt for the optimal value. Finally, the obtained optimal ELM model proceeds to perform the thyroid disease diagnosis tasks using the most discriminative new feature set and the optimal parameters. The effectiveness of the resultant CAD system (PCA-ELM) has been rigorously estimated on a thyroid disease dataset which is taken from UCI machine learning repository. We compare it with other related methods in terms of their classification accuracy. Experimental results demonstrate that PCA-ELM outperforms other ones reported so far by 10-fold cross-validation method, with the mean accuracy of 97.73% and with the maximum accuracy of 98.1%. Besides, PCA-ELM performs much faster than support vector machines (SVM) based CAD system. Consequently, the proposed method PCA-ELM can be considered as a new powerful tools for diagnosing thyroid disease with excellent performance and less time. PMID:22327384

  4. VALIDATION OF HANFORD PERSONNEL AND EXTREMITY DOSIMETERS IN PLUTONIUM ENVIRONMENTS

    SciTech Connect

    Scherpelz, Robert I.; Fix, John J.; Rathbone, Bruce A.

    2000-02-10

    A study was performed in the Plutonium Finishing Plant to assess the performance of Hanford personnel neutron dosimetry. The study was assessed whole body dosimetry and extremity dosimetry performance. For both parts of the study, the TEPC was used as the principle instrument for characterizing workplace neutron fields. In the whole body study, 12.7-cm-diameter TEPCs were used in ten different locations in the facility. TLD and TED personnel dosimeters were exposed on a water-filled phantom to enable a comparison of TEPC and dosimeter response. In the extremity study, 1.27-cm-diameter TEPCs were exposed inside the fingers of a gloveboxe glove. Extremity dosimeters were wrapped around the TEPCs. The glove was then exposed to six different cans of plutonium, simulating the exposure that a worker's fingers would receive in a glovebox. The comparison of TEPC-measured neutron dose equivalent to TLD-measured gamma dose equivalent provided neutron-to-gamma ratios that can be used to estimate the neutron dose equivalent received by a worker's finger based on the gamma readings of an extremity dosimeter. The study also utilized a Snoopy and detectors based on bubble technology for assessing neutron exposures, providing a comparison of the effectiveness of these instruments for workplace monitoring. The study concludes that the TLD component of the HCND performs adequately overall, with a positive bias of 30%, but exhibits excessive variability in individual results due to instabilities in the algorithm. The TED response was less variable but only 20% of the TEPC reference dose on average because of the low neutron energies involved. The neutron response of the HSD was more variable than the TLD component of the HCND and biased high by a factor of 8 overall due to its calibration to unmoderated 252Cf. The study recommends further work to correct instabilities in the HCND algorithm and to explore the potential shown by the bubble-based dosimeters.

  5. NOTE: Monte Carlo simulation of correction factors for IAEA TLD holders

    NASA Astrophysics Data System (ADS)

    Hultqvist, Martha; Fernández-Varea, José M.; Izewska, Joanna

    2010-03-01

    The IAEA standard thermoluminescent dosimeter (TLD) holder has been developed for the IAEA/WHO TLD postal dose program for audits of high-energy photon beams, and it is also employed by the ESTRO-QUALity assurance network (EQUAL) and several national TLD audit networks. Factors correcting for the influence of the holder on the TL signal under reference conditions have been calculated in the present work from Monte Carlo simulations with the PENELOPE code for 60Co γ-rays and 4, 6, 10, 15, 18 and 25 MV photon beams. The simulation results are around 0.2% smaller than measured factors reported in the literature, but well within the combined standard uncertainties. The present study supports the use of the experimentally obtained holder correction factors in the determination of the absorbed dose to water from the TL readings; the factors calculated by means of Monte Carlo simulations may be adopted for the cases where there are no measured data.

  6. Investigation of LiF, Mg and Ti (TLD-100) Reproducibility

    PubMed Central

    Sadeghi, M.; Sina, S.; Faghihi, R.

    2015-01-01

    LiF, Mg and Ti cubical TLD chips (known as TLD-100) are widely used for dosimetry purposes. The repeatability of TL dosimetry is investigated by exposing them to doses of (81, 162 and 40.5 mGy) with 662keV photons of Cs-137. A group of 40 cubical TLD chips was randomly selected from a batch and the values of Element Correction Coefficient (ECC) were obtained 4 times by irradiating them to doses of 81 mGy (two times), 162mGy and 40.5mGy. Results of this study indicate that the average reproducibility of ECC calculation for 40 TLDs is 1.5%, while these values for all chips do not exceed 5%. PMID:26688801

  7. Investigation of LiF, Mg and Ti (TLD-100) Reproducibility.

    PubMed

    Sadeghi, M; Sina, S; Faghihi, R

    2015-12-01

    LiF, Mg and Ti cubical TLD chips (known as TLD-100) are widely used for dosimetry purposes. The repeatability of TL dosimetry is investigated by exposing them to doses of (81, 162 and 40.5 mGy) with 662keV photons of Cs-137. A group of 40 cubical TLD chips was randomly selected from a batch and the values of Element Correction Coefficient (ECC) were obtained 4 times by irradiating them to doses of 81 mGy (two times), 162mGy and 40.5mGy. Results of this study indicate that the average reproducibility of ECC calculation for 40 TLDs is 1.5%, while these values for all chips do not exceed 5%. PMID:26688801

  8. Design of a personnel TLD badge for a power reactor beta/gamma spectrum

    SciTech Connect

    Quinn, D.M.; Labenski, T. )

    1983-10-01

    This paper reports that three basic challenges are inherent in the design of a thermoluminescent dosimeter for a power reactor beta/gamma spectrum: the dosimeter must meet the current standard for performance in laboratory testing, the dosimeter must properly respond to a power reactor spectrum that is different from that specified in the standard, and the dosimeter must function under field conditions. These challenges were met at the Indian Point 3 Nuclear Power Station by modifying the case of a commercial multi-element TLD to include varying thicknesses of tissue equivalent plastic absorbers over the elements. An algorithm was developed to correct the TLD responses for laboratory testing: however, in field use, shallow and deep dose are read directly from the TLD without the use of an algorithm.

  9. Operational comparison of TLD albedo dosemeters and solid state nuclear tracks detectors in fuel fabrication facilities.

    PubMed

    Tsujimura, N; Takada, C; Yoshida, T; Momose, T

    2007-01-01

    The authors carried out an operational study that compared the use of TLD albedo dosemeters and solid state nuclear tracks detector in plutonium environments of Japan Nuclear Cycle Development Institute, Tokai Works. A selected group of workers engaged in the fabrication process of MOX (Plutonium-Uranium mixed oxide) fuel wore both TLD albedo dosemeters and solid state nuclear tracks detectors. The TL readings were generally proportional to the counted etch-pits, and thus the dose equivalent results obtained from TLD albedo dosemeter agreed with those from solid state nuclear tracks detector within a factor of 1.5. This result indicates that, in the workplaces of the MOX fuel plants, the neutron spectrum remained almost constant in terms of time and space, and the appropriate range of field-specific correction with spectrum variations was small in albedo dosimetry. PMID:17337735

  10. HPC Colony II: FAST_OS II: Operating Systems and Runtime Systems at Extreme Scale

    SciTech Connect

    Moreira, Jose

    2013-11-13

    HPC Colony II has been a 36-month project focused on providing portable performance for leadership class machines—a task made difficult by the emerging variety of more complex computer architectures. The project attempts to move the burden of portable performance to adaptive system software, thereby allowing domain scientists to concentrate on their field rather than the fine details of a new leadership class machine. To accomplish our goals, we focused on adding intelligence into the system software stack. Our revised components include: new techniques to address OS jitter; new techniques to dynamically address load imbalances; new techniques to map resources according to architectural subtleties and application dynamic behavior; new techniques to dramatically improve the performance of checkpoint-restart; and new techniques to address membership service issues at scale.

  11. ExM:System Support for Extreme-Scale, Many-Task Applications

    SciTech Connect

    Katz, Daniel S

    2011-05-31

    The ever-increasing power of supercomputer systems is both driving and enabling the emergence of new problem-solving methods that require the effi cient execution of many concurrent and interacting tasks. Methodologies such as rational design (e.g., in materials science), uncertainty quanti fication (e.g., in engineering), parameter estimation (e.g., for chemical and nuclear potential functions, and in economic energy systems modeling), massive dynamic graph pruning (e.g., in phylogenetic searches), Monte-Carlo- based iterative fi xing (e.g., in protein structure prediction), and inverse modeling (e.g., in reservoir simulation) all have these requirements. These many-task applications frequently have aggregate computing needs that demand the fastest computers. For example, proposed next-generation climate model ensemble studies will involve 1,000 or more runs, each requiring 10,000 cores for a week, to characterize model sensitivity to initial condition and parameter uncertainty. The goal of the ExM project is to achieve the technical advances required to execute such many-task applications efficiently, reliably, and easily on petascale and exascale computers. In this way, we will open up extreme-scale computing to new problem solving methods and application classes. In this document, we report on combined technical progress of the collaborative ExM project, and the institutional financial status of the portion of the project at University of Chicago, over the rst 8 months (through April 30, 2011)

  12. Control system architecture of AMICA: a robotic instrument in an extreme environment

    NASA Astrophysics Data System (ADS)

    Di Rico, Gianluca; Ragni, Maurizio; Corcione, Leonardo; Giro, Enrico; Fantinel, Daniela

    2006-06-01

    AMICA is a camera conceived to automatically acquire infrared astronomical images in the extreme environment of Dome C (T ~ -70 °C, p ~ 640 mbar). For this reason, hardware and software are specially designed. They must guarantee the correct execution of observing procedures, while performing a continuous monitoring of the environmental conditions, the instrument status and the observing parameters, and a real-time adjustment of them when required. All temperature-sensitive components will be placed in a thermally controlled rack. The environmental control inside it is assigned to a Programmable Logic Controller (PLC). It is responsible, in particular, for the overall system start-up. Instrument status, mainly concerning vacuum level and temperatures inside the cryostat, is directly monitored by the local cPC, which sends instructions to the PLC in case of failure, in order to start appropriate restoring procedures. All hardware components are conceived to be easily and fast replaceable. Main tasks of the AMICA Control Software (ACS) are: telescope interaction, observation management, environment control, events handling, data storing. Because of the high frame rate, typical of infrared imaging, the acquisition system has been interfaced with an independent application (STS), to perform read-out electronics control, fast data processing (co-adding from chopping raw frames), parameters checking (such as exposure time, chopping frequency, etc.), and data output. The software design has a multithreading architecture, based on the Object Oriented approach and developed for Windows OS platforms.

  13. Groundwater artificial recharge solutions for integrated management of watersheds and aquifer systems under extreme drought scenarios

    NASA Astrophysics Data System (ADS)

    Lobo-Ferreira, Joao-Paulo; Oliveira, Luís.; Diamantino, Catarina

    2010-05-01

    The paper addresses groundwater artificial recharge solutions for integrated management of watersheds and aquifer systems under extreme drought scenarios. The conceptual idea of Aquifer Storage and Recovery (ASR) is considered as one of the scientific based solutions towards scientific based mitigation measures to climate variability and change in many parts of the world. In Portugal two European Union sponsored 6th Framework Programme for Research Projects have been addressing this topic, namely GABARDINE Project on "Groundwater artificial recharge based on alternative sources of water: Advanced integrated technologies and management" and the Coordinated Action ASEMWATERNet, a "Multi-Stakeholder Platform for ASEM S&T Cooperation on Sustainable Water Use". An application of Aquifer Storage and Recovery methodologies aiming drought mitigation and Integrated Water Resource Management of the Algarve (Portugal). The technique of artificial recharge of groundwater is used in many parts of the world with several aims, e.g. water storing in appropriate aquifers for the mitigation of future water needs during droughts or as protection against pollution or even for the recovery of groundwater quality. Artificial recharge of the aquifer systems of Campina de Faro and Silves-Querença is addressed in this paper, proposed to be an alternative to decrease the vulnerability of the Algarve to a future drought. Integrated management of water resources in the Algarve is not a clear issue since the last decade, when groundwater resources that supplied almost all water needs, have been drastically replaced by surface water stored in new reservoirs.

  14. A newly designed experimental system for exposure of mammalian cells to extremely low frequency magnetic fields.

    PubMed

    Miyakoshi, J; Ohtsu, S; Tatsumi-Miyajima, J; Takebe, H

    1994-03-01

    To examine the biological effects of extremely low frequency magnetic field (ELFMF), we have designed and manufactured a new equipment for long-term and high-density exposure of cells to ELFMF. The ELFMF exposure system consists of a generator of magnets with a built-in CO2 incubator, an alternating current (AC) power supply, a gas compressor and a thermocontroller for the incubator, and a cooling unit for the magnets. The CO2 incubator made of acrylic resin is inserted into the inner-space of the silicon steel strip-cores. In this system, the temperature of the incubator is maintained at 37 +/- 0.5 degrees C. The maximum magnetic flux density on the exposure area of the incubator is 500 mT (T; tesla) at a current of 556 Arms (rms; root mean square) at 50 Hz. The long-term (up to 120 hr) exposure of 400 mT ELFMF did not affect the growth of both HL60RG and CCRF-CEM cells originated from human leukemia. The post-X-irradiation exposure of 400 mT ELFMF for 2 hr also did not affect the radiation sensitivity of GM0637 and TAT2SF cells originated from a normal human and an ataxia telangiectasia patient. PMID:8057268

  15. Impact of the extreme 2009 wildfires in Victoria on the soil system and implications for fire behaviour

    NASA Astrophysics Data System (ADS)

    Doerr, Stefan; Shakesby, R. A.; Sheridan, G. J.; Lane, P. N. J.; Smith, H. G.; Bell, T.; Brooks, J.; Blake, W. H.

    2010-05-01

    The recent catastrophic wildfires near Melbourne in 2009 occurred during unprecedented extreme fire weather when dry northerly winds gusting up to 100 km/h coincided with the highest temperatures ever recorded in this region. These conditions, combined with the very high biomass of mature eucalypt forests (estimated to exceed 40 t/ha in places), very low fuel moisture conditions and steep slopes, generated extreme burning conditions. A rapid response project, funded by the NERC Urgency scheme, was launched to reconstruct heat input into the soils, and to determine associated effects on soil properties and seed bank survival. Three replicate sites were sampled for extremely high burn severity and high burn severity, and four for long unburnt control terrain, within mature mixed-species eucalypt forests near Marysville in April 2009. Additional exploratory sampling was carried out in 'rainforest'. Ash (where applicable) and surface soil (0-2.5 cm and 2.5-5 cm) were collected at 20 sample grid points at each site. Here we report on preliminary outcomes from soil water repellency determination, and seedbank germination experiments, which allow reconstructing of soil temperature and burn severity, and provide insights into fire behaviour, of this extreme event. Field and laboratory assessment of the soil suggest that the heat input to the soil was less than might be supposed given the extreme estimated fire intensity (>70,000 kW/m). Our data indicate that soil temperatures in the top 0-2.5 cm did not exceed ca 200°C. The limited heat input into the soil stands in stark contrast to the extreme fire intensity. We speculate that it resulted from an unusually fast-moving fire front associated with the extreme wind speeds, causing a short fire residence time. Whilst this fire event has been extreme in many respects, its impact on the soil system has clearly been less than what might have been expected. Thus it could be argued that the more extreme burning conditions that

  16. An evaluation of a coupled atmosphere-ocean modelling system for regional climate studies: extreme events in the North Atlantic

    NASA Astrophysics Data System (ADS)

    Mooney, Priscilla A.; Mulligan, Frank J.

    2013-04-01

    We investigate the ability of a coupled regional atmosphere-ocean modelling system to simulate two extreme events in the North Atlantic. In this study we use the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST; Warner et al.) modelling system with only the atmosphere and ocean models activated. COAWST couples the atmosphere model (Weather Research and Forecasting model; WRF) to the ocean model (Regional Ocean Modelling System; ROMS) with the Model Coupling Toolkit. Results from the coupled system are compared with atmosphere only simulations of North Atlantic storms to evaluate the performance of the coupled modelling system. Two extreme events (Hurricane Katia and Hurricane Irene) were chosen to assess the level of improvement (or otherwise) arising from coupling WRF with ROMS. These two hurricanes involve different dynamics and present different challenges to the modeling system. This provides a robust assessment of the advantages or disadvantages of coupling WRF with ROMS for regional climate modelling studies of extreme events in the North Atlantic. We examine the ability of the coupled modelling system to simulate these two extreme events by comparing modelled storm tracks, storm intensities, wind speeds and sea surface temperatures with observations in all cases. The effect of domain size, and two different planetary boundary layers used in WRF are also reported.

  17. On the reassessment of thermal neutron doses in TLD-100 by measuring the residual dose.

    PubMed

    Abraham, A; Weinstein, M; German, U; Alfassi, Z B

    2007-01-01

    By employing second readouts and the Phototransferred thermoluminescence (PTTL) method, high doses may be reassessed on the basis of residual dose information. It was shown in the past that for TLD-100, gamma doses can be reassessed by using a simple and efficient method, which consists of expanding the heating time to 30 s. In the present study, the 'extended time' method and the PTTL residual dose evaluations are used for reassessing thermal neutron doses when using TLD-100 crystals. Reassessment characteristics are presented for relatively low thermal neutron doses, in the range between approximately 1 and 18 mSv gamma dose equivalent. PMID:17507383

  18. Application of the TLD albedo technique for monitoring and interpretation of neutron stray radiation fields

    NASA Astrophysics Data System (ADS)

    Piesch, E.; Burgkhardt, B.

    1980-09-01

    A single sphere albedo technique with TLD 600/TLD 700 detectors has been applied in neutron monitoring to calibrate albedo dosimeters and to interpret neutron stray radiation fields in terms of neutron dose equivalent separated for the energy groups below 0.4 eV, 0.4-10 keV and 10 keV-10 MeV, and Eeff for fast neutrons. The paper describes the technique for field and personnel monitoring under the aspect of an on-line computer program for data recording and processing.

  19. Discrepancies between film and thermoluminescent dosimetry (TLD) readings at an operating power reactor

    SciTech Connect

    Quinn, D.M.

    1980-01-01

    The results of exposure measurements using film badges and thermoluminescent dosimetry (TLD) were compared at an operating nuclear power reactor. The film badge overresponded to the high-energy Nitrogen-16 gamma rays produced under power, while the TLD did not. Discussions of charged-particle equilibrium and energy dependence are included. The cause of the overresponse was determined to be the excess pair production electrons created because of the high atomic number in the lead energy-compensating shield surrounding the film and in the film itself.

  20. Practical considerations for TLD-400/700-based gamma ray dosimetry for BNCT applications in a high thermal neutron fluence.

    PubMed

    Martsolf, S W; Johnson, J E; Vostmyer, C E; Albertson, B D; Binney, S E

    1995-12-01

    Operating experience with thermoluminescent dosimeters used in a boron neutron capture therapy research project is reported. In particular, certain facets of the use of thermoluminescent dosimeters for gamma ray dose measurements in the presence of a high thermal neutron fluence are discussed, including a comparison of TLD-400 and TLD-700 for gamma ray dosimetry, annealing procedures, and the effects of neutrons (56Mn activation) on TLD-400. The TLD-400 were observed to have a thermal neutron sensitivity (due to 56Mn beta decay) of 1.5 x 10(-13) Gy per n cm-2. An algorithm was developed to correct for the 56Mn beta decay thermal neutron-induced effects on TLD-400 by using a two-stage thermoluminescent readout for the thermoluminescent dosimeter chips. PMID:7493815

  1. A thermoluminescence dosimetry system for personal monitoring in Ireland.

    PubMed

    Currivan, L; Spain, D; Donnelly, H; Colgan, P A

    2001-01-01

    In 1993 the decision was taken to replace film badges with thermoluminescence dosemeters (TLDs) as the main form of dosemeter for both whole-body and extremity monitoring at the Dosimetry Service of the Radiological Protection Institute of Ireland (RPII) in Dublin. A review of commercially available automatic TLD systems was carried out to identify the system which best met the RPII's requirements. This paper describes the dosimetry system used, and, in addition, discusses the problems encountered and how these were addressed. PMID:11586731

  2. Impacts of Irrigation on Daily Extremes in the Coupled Climate System

    NASA Technical Reports Server (NTRS)

    Puma, Michael J.; Cook, Benjamin I.; Krakauer, Nir; Gentine, Pierre; Nazarenka, Larissa; Kelly, Maxwell; Wada, Yoshihide

    2014-01-01

    Widespread irrigation alters regional climate through changes to the energy and water budgets of the land surface. Within general circulation models, simulation studies have revealed significant changes in temperature, precipitation, and other climate variables. Here we investigate the feedbacks of irrigation with a focus on daily extremes at the global scale. We simulate global climate for the year 2000 with and without irrigation to understand irrigation-induced changes. Our simulations reveal shifts in key climate-extreme metrics. These findings indicate that land cover and land use change may be an important contributor to climate extremes both locally and in remote regions including the low-latitudes.

  3. [Extreme types - a comparison of public health systems in Thuringia and the Warthegau].

    PubMed

    Vossen, J

    2013-11-01

    Special policing measures in Nazi Germany required centralisation in the public health service which was mainly achieved through the Law for the Unification of Municipal and State Health Administration in 1934. The long-term aim for public health officers was now hereditary and racial welfare. Several following legal regulations contributed to the implementation of a specific national-socialist health and social policy on the basis of racial hygiene and gave immense power to the health officers. Especially with the Law for the Prevention of Hereditarily Sick Offspring, compulsory sterilisation was legalised and resulted in about 400,000 victims up to 1945. The central force in this new system was the public health office. The most extreme variation of public health administration was launched in Thuringia, where professional powers and state authority implemented an extensive institutional machinery which managed to reinforce Nazi population policy almost to perfection. After the invasion of western Poland the Germans built up an inhumane regime in the annexed and occupied regions, persecuted and murdered the Polish population and tried to exterminate the Jewish people. Here the health officers of the Warthegau could promote a rigorously racial dominated population policy of segregation. PMID:24142373

  4. High-precision work distributions for extreme non-equilibrium processes in large systems

    NASA Astrophysics Data System (ADS)

    Hartmann, Alexander

    2014-03-01

    The distributions of work for strongly non-equilibrium processes are studied using a very general form of a large-deviation approach, which allows one to study distributions down to extremely small probabilities of almost arbitrary quantities of interest for equilibrium, non-equilibrium stationary and even non-stationary processes. The method is applied to varying quickly the external field in a wide range B = 3 <--> 0 for critical (T = 2 . 269) two-dimensional Ising system of size L × L = 128 × 128 . To obtain free energy differences from the work distributions, they must be studied in ranges where the probabilities are as small as 10-240, which is not possible using direct simulation approaches. By comparison with the exact free energies, one sees that the present approach allows one to obtain the free energy with a very high relative precision of 10-4. This works well also for non-zero field, i.e., for a case where standard umbrella-sampling methods seem to be not so efficient to calculate free energies. Furthermore, for the present case it is verified that the resulting distributions of work fulfill Crooks theorem with high precision. Finally, the free energy for the Ising magnet as a function of the field strength is obtained.

  5. Sources and transport systems for low energy extreme of ion implantation

    SciTech Connect

    Hershcovitch, A.; Batalin, V.A.; Bugaev, A.S.; Gushenets, V.I.; Alexeyenko, O.; Gurkova, E.; Johnson, B.M.; Kolomiets, A.A.; Kropachev, G.N.; Kuibeda, R.P.; Kulevoy, T.V.; Masunov, E.S.; Oks, E.M.; Pershin, V.I.; Polozov, S.M.; Poole, H.J.; Seleznev, D.N.; Storozhenko, P.A.; Vizir, A.; Svarovski, A.Ya.; Yakushin, P.; Yushkov, G.Yu.

    2010-06-06

    For the past seven years a joint research and development effort focusing on the design of steady state, intense ion sources has been in progress with the ultimate goal being to meet the two, energy extreme range needs of mega-electron-volt and 100's of electron-volt ion implanters. However, since the last Fortier is low energy ion implantation, focus of the endeavor has shifted to low energy ion implantation. For boron cluster source development, we started with molecular ions of decaborane (B{sub 10}H{sub 14}), octadecaborane (B{sub 18}H{sub 22}), and presently our focus is on carborane (C{sub 2}B{sub 10}H{sub 12}) ions developing methods for mitigating graphite deposition. Simultaneously, we are developing a pure boron ion source (without a working gas) that can form the basis for a novel, more efficient, plasma immersion source. Our Calutron-Berna ion source was converted into a universal source capable of switching between generating molecular phosphorous P{sub 4}{sup +}, high charge state ions, as well as other types of ions. Additionally, we have developed transport systems capable of transporting a very large variety of ion species, and simulations of a novel gasless/plasmaless ion beam deceleration method were also performed.

  6. An Automated System for Skeletal Maturity Assessment by Extreme Learning Machines

    PubMed Central

    Mansourvar, Marjan; Shamshirband, Shahaboddin; Raj, Ram Gopal; Gunalan, Roshan; Mazinani, Iman

    2015-01-01

    Assessing skeletal age is a subjective and tedious examination process. Hence, automated assessment methods have been developed to replace manual evaluation in medical applications. In this study, a new fully automated method based on content-based image retrieval and using extreme learning machines (ELM) is designed and adapted to assess skeletal maturity. The main novelty of this approach is it overcomes the segmentation problem as suffered by existing systems. The estimation results of ELM models are compared with those of genetic programming (GP) and artificial neural networks (ANNs) models. The experimental results signify improvement in assessment accuracy over GP and ANN, while generalization capability is possible with the ELM approach. Moreover, the results are indicated that the ELM model developed can be used confidently in further work on formulating novel models of skeletal age assessment strategies. According to the experimental results, the new presented method has the capacity to learn many hundreds of times faster than traditional learning methods and it has sufficient overall performance in many aspects. It has conclusively been found that applying ELM is particularly promising as an alternative method for evaluating skeletal age. PMID:26402795

  7. ELF (Extremely Low Frequency) communications system ecological monitoring program: Slime mold studies

    NASA Astrophysics Data System (ADS)

    Goodman, Eugene; Greenebaum, Ben

    1990-01-01

    It was previously shown that continuous exposure of the slime mold Physarum polycephalum to extremely low frequency (ELF) electromagnetic fields (EMF) simulating those generated by the Navy's ELF communication system (then Project Sanguine) could depress the rate of respiration, and lengthen the mitotic cell cycle. In a series of experiments beginning in 1981 and ending in 1987, it was determined that whether exposing Physarum to the field environment around the Wisconsin Transmitting Facility (WTF) could induce an altered physiological state. A laboratory component was also included to help verify methodology and to supplement studies performed at the WTF. Initially, the experimental effort was directed to devising methods to maintain axenic Physarum cultures under ambient environmental conditions. This involved using growth chambers that admit the electric field or current density from the surrounding environment; the cultures were returned to the laboratory for analysis. The successful methods placed the organism on an agar bed inside double containment and introduced the samples to be assayed into shaken liquid culture medium upon arrival at the laboratory. Both WTF-generated electromagnetic fields and background strengths were measured with the help of IITRI at study locations near the antenna, at the west ground of the WTF antenna, as well as at control sites.

  8. An Automated System for Skeletal Maturity Assessment by Extreme Learning Machines.

    PubMed

    Mansourvar, Marjan; Shamshirband, Shahaboddin; Raj, Ram Gopal; Gunalan, Roshan; Mazinani, Iman

    2015-01-01

    Assessing skeletal age is a subjective and tedious examination process. Hence, automated assessment methods have been developed to replace manual evaluation in medical applications. In this study, a new fully automated method based on content-based image retrieval and using extreme learning machines (ELM) is designed and adapted to assess skeletal maturity. The main novelty of this approach is it overcomes the segmentation problem as suffered by existing systems. The estimation results of ELM models are compared with those of genetic programming (GP) and artificial neural networks (ANNs) models. The experimental results signify improvement in assessment accuracy over GP and ANN, while generalization capability is possible with the ELM approach. Moreover, the results are indicated that the ELM model developed can be used confidently in further work on formulating novel models of skeletal age assessment strategies. According to the experimental results, the new presented method has the capacity to learn many hundreds of times faster than traditional learning methods and it has sufficient overall performance in many aspects. It has conclusively been found that applying ELM is particularly promising as an alternative method for evaluating skeletal age. PMID:26402795

  9. Thermodynamic sensitivities in observed and simulated extreme-rain-producing mesoscale convective systems

    NASA Astrophysics Data System (ADS)

    Schumacher, R. S.; Peters, J. M.

    2015-12-01

    Mesoscale convective systems (MCSs) are responsible for a large fraction of warm-season extreme rainfall events over the continental United States, as well as other midlatitude regions globally. The rainfall production in these MCSs is determined by numerous factors, including the large-scale forcing for ascent, the organization of the convection, cloud microphysical processes, and the surrounding thermodynamic and kinematic environment. Furthermore, heavy-rain-producing MCSs are most common at night, which means that well-studied mechanisms for MCS maintenance and organization such as cold pools (gravity currents) are not always at work. In this study, we use numerical model simulations and recent field observations to investigate the sensitivity of low-level MCS structures, and their influences on rainfall, to the details of the thermodynamic environment. In particular, small alterations to the initial conditions in idealized and semi-idealized simulations result in comparatively large precipitation changes, both in terms of the intensity and the spatial distribution. The uncertainties in the thermodynamic enviroments in the model simulations will be compared with high-resolution observations from the Plains Elevated Convection At Night (PECAN) field experiment in 2015. The results have implications for the paradigms of "surface-based" versus "elevated" convection, as well as for the predictability of warm-season convective rainfall.

  10. Numerical implementation of time-dependent density functional theory for extended systems in extreme environments

    SciTech Connect

    Baczewski, Andrew David; Shulenburger, Luke; Desjarlais, Michael Paul; Magyar, Rudolph J.

    2014-02-01

    In recent years, DFT-MD has been shown to be a useful computational tool for exploring the properties of WDM. These calculations achieve excellent agreement with shock compression experiments, which probe the thermodynamic parameters of the Hugoniot state. New X-ray Thomson Scattering diagnostics promise to deliver independent measurements of electronic density and temperature, as well as structural information in shocked systems. However, they require the development of new levels of theory for computing the associated observables within a DFT framework. The experimentally observable x-ray scattering cross section is related to the electronic density-density response function, which is obtainable using TDDFT - a formally exact extension of conventional DFT that describes electron dynamics and excited states. In order to develop a capability for modeling XRTS data and, more generally, to establish a predictive capability for rst principles simulations of matter in extreme conditions, real-time TDDFT with Ehrenfest dynamics has been implemented in an existing PAW code for DFT-MD calculations. The purpose of this report is to record implementation details and benchmarks as the project advances from software development to delivering novel scienti c results. Results range from tests that establish the accuracy, e ciency, and scalability of our implementation, to calculations that are veri ed against accepted results in the literature. Aside from the primary XRTS goal, we identify other more general areas where this new capability will be useful, including stopping power calculations and electron-ion equilibration.