Science.gov

Sample records for extended field radiation

  1. Extended-field radiation therapy for carcinoma of the cervix

    SciTech Connect

    Podczaski, E.; Stryker, J.A.; Kaminski, P.; Ndubisi, B.; Larson, J.; DeGeest, K.; Sorosky, J.; Mortel, R. )

    1990-07-15

    The survival of cervical carcinoma patients with paraaortic/high common iliac nodal metastases was evaluated by retrospective chart review during a 13-year interval. Thirty-three patients with cervical carcinoma and surgically documented nodal metastases received primary, extended-field radiation therapy. Overall 2-year and 5-year actuarial survival rates after diagnosis were 37% and 31%, respectively. Survival was analyzed in terms of the variables patient age, clinical stage, tumor histologic type, the presence of enlarged paraaortic/high common iliac lymph nodes, the extent of nodal involvement (microscopic versus macroscopic), the presence of intraperitoneal disease, and whether intracavitary brachytherapy was administered. The use of intracavitary radiation therapy was associated with improved local control and survival (P = 0.017). None of the other variables were statistically related to patient survival. Twenty-two of the patients died of cervical cancer and five are surviving without evidence of cancer. Four patients died of intercurrent disease. Two patients developed bowel-related radiation complications; both patients received chemotherapy concurrent with the radiation therapy. One of the two patients died of radiation enteritis. The use of extended-field radiation therapy does benefit a small group of patients and may result in extended patient survival.

  2. Radiation field from an extended planar-anode on HERMES III

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A.; Poukey, J.W.; Beutler, D.E.; Carlson, G.A.; Baldwin, G.T.; Sheriden, T.; Mock, R.; Klinger, R.S.; Knott, D.P. )

    1989-12-01

    The bremsstrahlung field from an extended planar-anode diode with an annular cathode tip on the 16-TW HERMES III electron accelerator is measured and compared with predictions. Measurements confirm predictions and demonstrate that the diode provides a versatile large-area source of gamma radiation. Versatility is obtained by adjustment of the anode-cathode gap, which affects electron trajectories while simultaneously maintaining constant diode impedance. The adjustment permits the generation of average dose rates from about 1.2 {times} 10{sup 12} rad/s over 3100 cm{sup 2} to about 5.6 {times} 10{sup 12} rad/s over 700 cm{sup 2}, without destruction of the bremsstrahlung target.

  3. Preliminary outcome and toxicity report of extended-field, intensity-modulated radiation therapy for gynecologic malignancies

    SciTech Connect

    Salama, Joseph K. . E-mail: jsalama@radonc.uchicago.edu; Mundt, Arno J.; Roeske, John; Mehta, Neil

    2006-07-15

    Purpose: The aim of this article is to report a preliminary analysis of our initial clinical experience with extended-field intensity-modulated radiotherapy for gynecologic malignancies. Methods and Materials: Between November 2002 and May 2005, 13 women with gynecologic malignancies were treated with extended-field radiation therapy. Of the women, 7 had endometrial cancer, 4 cervical cancer, 1 recurrent endometrial cancer, and 1 suspected cervical cancer. All women underwent computed tomography planning, with the upper vagina, parametria, and uterus (if present) contoured within the CTV. In addition, the clinical target volume contained the pelvic and presacral lymph nodes as well as the para-aortic lymph nodes. All acute toxicity was scored according to the Common Terminology Criteria for Adverse Events (CTCAE v 3.0). All late toxicity was scored using the Radiation Therapy Oncology Group late toxicity score. Results: The median follow-up was 11 months. Extended-field intensity-modulated radiation therapy (IMRT) for gynecologic malignancies was well tolerated. Two patients experienced Grade 3 or higher toxicity. Both patients were treated with concurrent cisplatin based chemotherapy. Neither patient was planned with bone marrow sparing. Eleven patients had no evidence of late toxicity. One patient with multiple previous surgeries experienced a bowel obstruction. One patient with bilateral grossly involved and unresectable common iliac nodes experienced bilateral lymphedema. Extended-field-IMRT achieved good local control with only 1 patient, who was metastatic at presentation, and 1 patient not able to complete treatment, experiencing in-field failure. Conclusions: Extended-field IMRT is safe and effective with a low incidence of acute toxicity. Longer follow-up is needed to assess chronic toxicity, although early results are promising.

  4. Split-field vs extended-field intensity-modulated radiation therapy plans for oropharyngeal cancer: Which spares the larynx? Which spares the thyroid?

    SciTech Connect

    Yu, Yao; Chen, Josephine; Leary, Celeste I.; Shugard, Erin; Yom, Sue S.

    2016-07-01

    Radiation of the low neck can be accomplished using split-field intensity-modulated radiation therapy (sf-IMRT) or extended-field intensity-modulated radiation therapy (ef-IMRT). We evaluated the effect of these treatment choices on target coverage and thyroid and larynx doses. Using data from 14 patients with cancers of the oropharynx, we compared the following 3 strategies for radiating the low neck: (1) extended-field IMRT, (2) traditional split-field IMRT with an initial cord-junction block to 40 Gy, followed by a full-cord block to 50 Gy, and (3) split-field IMRT with a full-cord block to 50 Gy. Patients were planned using each of these 3 techniques. To facilitate comparison, extended-field plans were normalized to deliver 50 Gy to 95% of the neck volume. Target coverage was assessed using the dose to 95% of the neck volume (D{sub 95}). Mean thyroid and larynx doses were computed. Extended-field IMRT was used as the reference arm; the mean larynx dose was 25.7 ± 7.4 Gy, and the mean thyroid dose was 28.6 ± 2.4 Gy. Split-field IMRT with 2-step blocking reduced laryngeal dose (mean larynx dose 15.2 ± 5.1 Gy) at the cost of a moderate reduction in target coverage (D{sub 95} 41.4 ± 14 Gy) and much higher thyroid dose (mean thyroid dose 44.7 ± 3.7 Gy). Split-field IMRT with initial full-cord block resulted in greater laryngeal sparing (mean larynx dose 14.2 ± 5.1 Gy) and only a moderately higher thyroid dose (mean thyroid dose 31 ± 8 Gy) but resulted in a significant reduction in target coverage (D{sub 95} 34.4 ± 15 Gy). Extended-field IMRT comprehensively covers the low neck and achieves acceptable thyroid and laryngeal sparing. Split-field IMRT with a full-cord block reduces laryngeal doses to less than 20 Gy and spares the thyroid, at the cost of substantially reduced coverage of the low neck. Traditional 2-step split-field IMRT similarly reduces the laryngeal dose but also reduces low-neck coverage and delivers very high doses to the thyroid.

  5. Split-field vs extended-field intensity-modulated radiation therapy plans for oropharyngeal cancer: Which spares the larynx? Which spares the thyroid?

    PubMed

    Yu, Yao; Chen, Josephine; Leary, Celeste I; Shugard, Erin; Yom, Sue S

    2016-01-01

    Radiation of the low neck can be accomplished using split-field intensity-modulated radiation therapy (sf-IMRT) or extended-field intensity-modulated radiation therapy (ef-IMRT). We evaluated the effect of these treatment choices on target coverage and thyroid and larynx doses. Using data from 14 patients with cancers of the oropharynx, we compared the following 3 strategies for radiating the low neck: (1) extended-field IMRT, (2) traditional split-field IMRT with an initial cord-junction block to 40Gy, followed by a full-cord block to 50Gy, and (3) split-field IMRT with a full-cord block to 50Gy. Patients were planned using each of these 3 techniques. To facilitate comparison, extended-field plans were normalized to deliver 50Gy to 95% of the neck volume. Target coverage was assessed using the dose to 95% of the neck volume (D95). Mean thyroid and larynx doses were computed. Extended-field IMRT was used as the reference arm; the mean larynx dose was 25.7 ± 7.4Gy, and the mean thyroid dose was 28.6 ± 2.4Gy. Split-field IMRT with 2-step blocking reduced laryngeal dose (mean larynx dose 15.2 ± 5.1Gy) at the cost of a moderate reduction in target coverage (D95 41.4 ± 14Gy) and much higher thyroid dose (mean thyroid dose 44.7 ± 3.7Gy). Split-field IMRT with initial full-cord block resulted in greater laryngeal sparing (mean larynx dose 14.2 ± 5.1Gy) and only a moderately higher thyroid dose (mean thyroid dose 31 ± 8Gy) but resulted in a significant reduction in target coverage (D95 34.4 ± 15Gy). Extended-field IMRT comprehensively covers the low neck and achieves acceptable thyroid and laryngeal sparing. Split-field IMRT with a full-cord block reduces laryngeal doses to less than 20Gy and spares the thyroid, at the cost of substantially reduced coverage of the low neck. Traditional 2-step split-field IMRT similarly reduces the laryngeal dose but also reduces low-neck coverage and delivers very high doses to the thyroid.

  6. Extended Ehrenfest theorem with radiative corrections

    NASA Astrophysics Data System (ADS)

    de la Peña, L.; Cetto, A. M.; Valdés-Hernández, A.

    2015-10-01

    A set of basic evolution equations for the mean values of dynamical variables is obtained from the Fokker-Planck equation applied to the general problem of a particle subject to a random force. The specific case of stochastic electrodynamics is then considered, in which the random force is due to the zero-point radiation field. Elsewhere it has been shown that when this system reaches a state of energy balance, it becomes controlled by an equation identical to Schrödinger’s, if the radiationless approximation is made. The Fokker-Planck equation was shown to lead to the Ehrenfest theorem under such an approximation. Here we show that when the radiative terms are not neglected, an extended form of the Ehrenfest equation is obtained, from which follow, among others, the correct formulas for the atomic lifetimes and the (nonrelativistic) Lamb shift.

  7. Radiation comb generation with extended Josephson junctions

    SciTech Connect

    Solinas, P.; Bosisio, R.; Giazotto, F.

    2015-09-21

    We propose the implementation of a Josephson radiation comb generator based on an extended Josephson junction subject to a time dependent magnetic field. The junction critical current shows known diffraction patterns and determines the position of the critical nodes when it vanishes. When the magnetic flux passes through one of such critical nodes, the superconducting phase must undergo a π-jump to minimize the Josephson energy. Correspondingly, a voltage pulse is generated at the extremes of the junction. Under periodic driving, this allows us to produce a comb-like voltage pulses sequence. In the frequency domain, it is possible to generate up to hundreds of harmonics of the fundamental driving frequency, thus mimicking the frequency comb used in optics and metrology. We discuss several implementations through a rectangular, cylindrical, and annular junction geometries, allowing us to generate different radiation spectra and to produce an output power up to 10 pW at 50 GHz for a driving frequency of 100 MHz.

  8. High-Dose and Extended-Field Intensity Modulated Radiation Therapy for Early-Stage NK/T-Cell Lymphoma of Waldeyer's Ring: Dosimetric Analysis and Clinical Outcome

    SciTech Connect

    Bi, Xi-Wen; Li, Ye-Xiong Fang, Hui; Jin, Jing; Wang, Wei-Hu; Wang, Shu-Lian; Liu, Yue-Ping; Song, Yong-Wen; Ren, Hua; Dai, Jian-Rong

    2013-12-01

    Purpose: To assess the dosimetric benefit, treatment outcome, and toxicity of high-dose and extended-field intensity modulated radiation therapy (IMRT) in patients with early-stage NK/T-cell lymphoma of Waldeyer's ring (WR-NKTCL). Methods and Materials: Thirty patients with early-stage WR-NKTCL who received extended-field IMRT were retrospectively reviewed. The prescribed dose was 50 Gy to the primary involved regions and positive cervical lymph nodes (planning target volume requiring radical irradiation [PTV{sub 50}]) and 40 Gy to the negative cervical nodes (PTV{sub 40}). Dosimetric parameters for the target volume and critical normal structures were evaluated. Locoregional control (LRC), overall survival (OS), and progression-free survival (PFS) were calculated using the Kaplan-Meier method. Results: The median mean doses to the PTV{sub 50} and PTV{sub 40} were 53.2 Gy and 43.0 Gy, respectively. Only 1.4% of the PTV{sub 50} and 0.9% of the PTV{sub 40} received less than 95% of the prescribed dose, indicating excellent target coverage. The average mean doses to the left and right parotid glands were 27.7 and 28.4 Gy, respectively. The 2-year OS, PFS, and LRC rates were 71.2%, 57.4%, and 87.8%. Most acute toxicities were grade 1 to 2, except for grade ≥3 dysphagia and mucositis. The most common late toxicity was grade 1-2 xerostomia, and no patient developed any ≥grade 3 late toxicities. A correlation between the mean dose to the parotid glands and the degree of late xerostomia was observed. Conclusions: IMRT achieves excellent target coverage and dose conformity, as well as favorable survival and locoregional control rates with acceptable toxicities in patients with WR-NKTCL.

  9. Extended range radiation dose-rate monitor

    DOEpatents

    Valentine, Kenneth H.

    1988-01-01

    An extended range dose-rate monitor is provided which utilizes the pulse pileup phenomenon that occurs in conventional counting systems to alter the dynamic response of the system to extend the dose-rate counting range. The current pulses from a solid-state detector generated by radiation events are amplified and shaped prior to applying the pulses to the input of a comparator. The comparator generates one logic pulse for each input pulse which exceeds the comparator reference threshold. These pulses are integrated and applied to a meter calibrated to indicate the measured dose-rate in response to the integrator output. A portion of the output signal from the integrator is fed back to vary the comparator reference threshold in proportion to the output count rate to extend the sensitive dynamic detection range by delaying the asymptotic approach of the integrator output toward full scale as measured by the meter.

  10. Duodenal and Other Gastrointestinal Toxicity in Cervical and Endometrial Cancer Treated With Extended-Field Intensity Modulated Radiation Therapy to Paraaortic Lymph Nodes

    SciTech Connect

    Poorvu, Philip D.; Sadow, Cheryl A.; Townamchai, Kanokpis; Damato, Antonio L.; Viswanathan, Akila N.

    2013-04-01

    Purpose: To characterize the rates of acute and late duodenal and other gastrointestinal (GI) toxicities among patients treated for cervical and endometrial cancers with extended-field intensity modulated radiation therapy (EF-IMRT) to the paraaortic nodes and to analyze dose-volume relationships of GI toxicities. Methods and Materials: Fifty-three patients with endometrial or cervical cancer underwent EF-IMRT to the paraaortic nodes, of whom 46 met the inclusion criteria for GI toxicity and 45 for duodenal toxicity analysis. The median prescribed dose to the paraaortic nodes was 54 Gy (range, 41.4-65 Gy). The 4 duodenal segments, whole duodenum, small bowel loops, peritoneum, and peritoneum plus retroperitoneal segments of colon were contoured retrospectively, and dosimetric analysis was performed to identify dose-volume relationships to grade ≥3 acute (<90 day) and late (≥90 day) GI toxicity. Results: Only 3/46 patients (6.5%) experienced acute grade ≥3 GI toxicity and 3/46 patients (6.5%) experienced late grade ≥3 GI toxicity. The median dose administered to these 6 patients was 50.4 Gy. One of 12 patients who received 63 to 65 Gy at the level of the renal hilum experienced grade 3 GI toxicity. Dosimetric analysis of patients with and without toxicity revealed no differences between the mean absolute or fractional volumes at any 5-Gy interval between 5 Gy and the maximum dose. None of the patients experienced duodenal toxicity. Conclusions: Treatment of paraaortic nodes with IMRT is associated with low rates of GI toxicities and no duodenal-specific toxicity, including patients treated with concurrent chemotherapy. This technique may allow sufficient dose sparing of the bowel to enable safe dose escalation to at least 65 Gy.

  11. Gamma radiation field intensity meter

    DOEpatents

    Thacker, L.H.

    1994-08-16

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

  12. Gamma radiation field intensity meter

    DOEpatents

    Thacker, Louis H.

    1995-01-01

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

  13. Gamma radiation field intensity meter

    DOEpatents

    Thacker, Louis H.

    1994-01-01

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

  14. Gamma radiation field intensity meter

    SciTech Connect

    Thacker, L.H.

    1995-10-17

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

  15. Fast Flat Fields from Moving Extended Sources

    NASA Astrophysics Data System (ADS)

    Dalrymple, N. E.; Bianda, M.

    2002-05-01

    A person wearing dirty spectacles corrects images by observing an extended object and moving his or her head. Details that do not appear to move with the observed object must be due to optical imperfections. In the same manner, the relative pixel gains of a CCD camera observing through a movable optical system can be calculated. The result is a flat field table that may be used repeatedly to correct subsequent images. A fast flat fielding algorithm has been developed for solar observations that uses only two exposures to compute a flat field. During each exposure the source image is linearly scanned across the field of view. The two images are then mated together. The method is valid in cases where the intensity of the observed source changes slowly with respect to the camera exposure time, where the optical configuration remains constant during the scans, and where the path of motion is known or can be deduced from the images. For a camera with 2048x2048 pixels the computation requires about 30 s of processing time on a Sun 450 and yields a result that is comparable to a Kuhn-Lin flat field, which requires one hour of processing time on the same system.

  16. Extended Field Intensity Modulated Radiation Therapy With Concomitant Boost for Lymph Node–Positive Cervical Cancer: Analysis of Regional Control and Recurrence Patterns in the Positron Emission Tomography/Computed Tomography Era

    SciTech Connect

    Vargo, John A.; Kim, Hayeon; Choi, Serah; Sukumvanich, Paniti; Olawaiye, Alexander B.; Kelley, Joseph L.; Edwards, Robert P.; Comerci, John T.; Beriwal, Sushil

    2014-12-01

    Purpose: Positron emission tomography/computed tomography (PET/CT) is commonly used for nodal staging in locally advanced cervical cancer; however the false negative rate for para-aortic disease are 20% to 25% in PET-positive pelvic nodal disease. Unless surgically staged, pelvis-only treatment may undertreat para-aortic disease. We have treated patients with PET-positive nodes with extended field intensity modulated radiation therapy (IMRT) to address the para-aortic region prophylactically with concomitant boost to involved nodes. The purpose of this study was to assess regional control rates and recurrence patterns. Methods and Materials: Sixty-one patients with cervical cancer (stage IBI-IVA) diagnosed from 2003 to 2012 with PET-avid pelvic nodes treated with extended field IMRT (45 Gy in 25 fractions with concomitant boost to involved nodes to a median of 55 Gy in 25 fractions) with concurrent cisplatin and brachytherapy were retrospectively analyzed. The nodal location was pelvis-only in 41 patients (67%) and pelvis + para-aortic in 20 patients (33%). There were a total of 179 nodes, with a median number of positive nodes of 2 (range, 1-16 nodes) per patient and a median nodal size of 1.8 cm (range, 0.7-4.5 cm). Response was assessed by PET/CT at 12 to 16 weeks. Results: Complete clinical and imaging response at the first follow-up visit was seen in 77% of patients. At a mean follow-up time of 29 months (range, 3-116 months), 8 patients experienced recurrence. The sites of persistent/recurrent disease were as follows: cervix 10 (16.3%), regional nodes 3 (4.9%), and distant 14 (23%). The rate of para-aortic failure in patients with pelvic-only nodes was 2.5%. There were no significant differences in recurrence patterns by the number/location of nodes, largest node size, or maximum node standardized uptake value. The rate of late grade 3+ adverse events was 4%. Conclusions: Extended field IMRT was well tolerated and resulted in low regional recurrence

  17. Small fields: Nonequilibrium radiation dosimetry

    SciTech Connect

    Das, Indra J.; Ding, George X.; Ahnesjoe, Anders

    2008-01-15

    Advances in radiation treatment with beamlet-based intensity modulation, image-guided radiation therapy, and stereotactic radiosurgery (including specialized equipments like CyberKnife, Gamma Knife, tomotherapy, and high-resolution multileaf collimating systems) have resulted in the use of reduced treatment fields to a subcentimeter scale. Compared to the traditional radiotherapy with fields {>=}4x4 cm{sup 2}, this can result in significant uncertainty in the accuracy of clinical dosimetry. The dosimetry of small fields is challenging due to nonequilibrium conditions created as a consequence of the secondary electron track lengths and the source size projected through the collimating system that are comparable to the treatment field size. It is further complicated by the prolonged electron tracks in the presence of low-density inhomogeneities. Also, radiation detectors introduced into such fields usually perturb the level of disequilibrium. Hence, the dosimetric accuracy previously achieved for standard radiotherapy applications is at risk for both absolute and relative dose determination. This article summarizes the present knowledge and gives an insight into the future procedures to handle the nonequilibrium radiation dosimetry problems. It is anticipated that new miniature detectors with controlled perturbations and corrections will be available to meet the demand for accurate measurements. It is also expected that the Monte Carlo techniques will increasingly be used in assessing the accuracy, verification, and calculation of dose, and will aid perturbation calculations of detectors used in small and highly conformal radiation beams.

  18. Extending the Principal Axis Theorem to Fields Other than R.

    ERIC Educational Resources Information Center

    Friedberg, Stephen H.

    1990-01-01

    That the principal axis theorem does not extend to any finite field is demonstrated. Presented are four examples that illustrate the difficulty in extending the principal axis theorem to fields other than the field of real numbers. Included are a theorem and proof that uses only a simple counting argument. (KR)

  19. Effective field theory of gravity for extended objects

    SciTech Connect

    Goldberger, Walter D.; Rothstein, Ira Z.

    2006-05-15

    Using effective field theory (EFT) methods we present a Lagrangian formalism which describes the dynamics of nonrelativistic extended objects coupled to gravity. The formalism is relevant to understanding the gravitational radiation power spectra emitted by binary star systems, an important class of candidate signals for gravitational wave observatories such as LIGO or VIRGO. The EFT allows for a clean separation of the three relevant scales: r{sub s}, the size of the compact objects, r, the orbital radius, and r/v, the wavelength of the physical radiation (where the velocity v is the expansion parameter). In the EFT, radiation is systematically included in the v expansion without the need to separate integrals into near zones and radiation zones. Using the EFT, we show that the renormalization of ultraviolet divergences which arise at v{sup 6} in post-Newtonian (PN) calculations requires the presence of two nonminimal worldline gravitational couplings linear in the Ricci curvature. However, these operators can be removed by a redefinition of the metric tensor, so that the divergences arising at v{sup 6} have no physically observable effect. Because in the EFT finite size features are encoded in the coefficients of nonminimal couplings, this implies a simple proof of the decoupling of internal structure for spinless objects to at least order v{sup 6}. Neglecting absorptive effects, we find that the power counting rules of the EFT indicate that the next set of short distance operators, which are quadratic in the curvature and are associated with tidal deformations, does not play a role until order v{sup 10}. These operators, which encapsulate finite size properties of the sources, have coefficients that can be fixed by a matching calculation. By including the most general set of such operators, the EFT allows one to work within a point-particle theory to arbitrary orders in v.

  20. Mechanics of isolated extended bodies in classical field theories

    NASA Astrophysics Data System (ADS)

    Harte, Abraham Isaiah

    2007-08-01

    This thesis discusses a number of issues related to the description and motion of extended matter distributions in certain classical field theories. Particular emphasis is placed on general relativity and Maxwell theory, although many results also apply in related formalisms. They are obtained by extending and applying a series of ideas originally developed by W. G. Dixon to understand the mechanics of isolated bodies. Since this formalism is not well- known, we provide an extensive review in a unified form. This elucidates the structure of an object's stress-energy tensor and electromagnetic current vector. Multipole decompositions of these objects are also studied in considerable detail, and are designed to automatically "factor out" the relevant conservation laws. In the case of charge-current vectors, we show how to extend these results to also take into account the assumed smoothness and compactness of the physical matter. This allows essentially all reasonable current configurations with a given total charge to be parameterized without any reference to the spacetime structure. Such constructions provide natural methods for comparing the properties of current distributions in different systems. They also simplify the study of "rigid" currents. It is found that such objects cannot generally exist without allowing for the presence of singularities. An even stronger result applies to the nonexistence of rigid number density vectors in systems where the total number of particles is fixed. These formal developments are applied in various way to study the motions of various compact extended bodies. The first case considered here is that of an uncharged test mass embedded in a spatially-flat Friedmann-Robertson-Walker universe. It is shown that even with zero (global) momentum, such an object may adjust its mass and trajectory merely by changing shape. Mass shifts are in fact unavoidable in almost all cases, and could be significant for galactic superclusters. This

  1. Extending Gurwitsch's field theory of consciousness.

    PubMed

    Yoshimi, Jeff; Vinson, David W

    2015-07-01

    Aron Gurwitsch's theory of the structure and dynamics of consciousness has much to offer contemporary theorizing about consciousness and its basis in the embodied brain. On Gurwitsch's account, as we develop it, the field of consciousness has a variable sized focus or "theme" of attention surrounded by a structured periphery of inattentional contents. As the field evolves, its contents change their status, sometimes smoothly, sometimes abruptly. Inner thoughts, a sense of one's body, and the physical environment are dominant field contents. These ideas can be linked with (and help unify) contemporary theories about the neural correlates of consciousness, inattention, the small world structure of the brain, meta-stable dynamics, embodied cognition, and predictive coding in the brain.

  2. Gravitational radiation resistance, radiation damping and field fluctuations

    NASA Astrophysics Data System (ADS)

    Schaefer, G.

    1981-03-01

    Application is made of two different generalized fluctuation-dissipation theorems and their derivations to the calculation of the gravitational quadrupole radiation resistance using the radiation-reaction force given by Misner, Thorne and Wheeler and the usual tidal force on one hand and the tidal force and the free gravitational radiation field on the other hand. The quantum-mechanical version (including thermal generalizations) of the well known classical quadrupole radiation damping formula is obtained as a function of the radiation resistance.

  3. Radiative braking in the extended exosphere of GJ 436 b

    NASA Astrophysics Data System (ADS)

    Bourrier, V.; Ehrenreich, D.; Lecavelier des Etangs, A.

    2015-10-01

    The recent detection of a giant exosphere surrounding the warm Neptune GJ 436 b has shed new light on the evaporation of close-in planets, revealing that moderately irradiated, low-mass exoplanets could make exceptional targets for studying this mechanism and its impact on the exoplanet population. Three HST/STIS observations were performed in the Lyman-α line of GJ 436 at different epochs, showing repeatable transits with large depths and extended durations. Here, we study the role played by stellar radiation pressure on the structure of the exosphere and its transmission spectrum. We found that the neutral hydrogen atoms in the exosphere of GJ 436 b are not swept away by radiation pressure as shown to be the case for evaporating hot Jupiters. Instead, the low radiation pressure from the M-dwarf host star only brakes the gravitational fall of the escaping hydrogen toward the star and allows its dispersion within a large volume around the planet, yielding radial velocities up to about -120 km s -1 that match the observations. We performed numerical simulations with the EVaporating Exoplanets (EVE) code to study the influence of the escape rate, the planetary wind velocity, and the stellar photoionization. While these parameters are instrumental in shaping the exosphere and yield simulation results in general agreement with the observations, the spectra observed at the different epochs show specific, time-variable features that require additional physics.

  4. Extending the depth of field through unbalanced optical path difference.

    PubMed

    Chu, Kaiqin; George, Nicholas; Chi, Wanli

    2008-12-20

    We describe a simple method to extend the depth of field of a conventional camera by inserting a transparent annular ring in front of the pupil of the lens. The insertion of the ring creates an unbalanced optical path difference across the lens aperture, which partitions the pupil and leads to an extended depth of field. This system is analyzed by diffraction and random process theory. Experiments are reported that are in good agreement with the theory.

  5. Graphene Field Effect Transistor for Radiation Detection

    NASA Technical Reports Server (NTRS)

    Li, Mary J. (Inventor); Chen, Zhihong (Inventor)

    2016-01-01

    The present invention relates to a graphene field effect transistor-based radiation sensor for use in a variety of radiation detection applications, including manned spaceflight missions. The sensing mechanism of the radiation sensor is based on the high sensitivity of graphene in the local change of electric field that can result from the interaction of ionizing radiation with a gated undoped silicon absorber serving as the supporting substrate in the graphene field effect transistor. The radiation sensor has low power and high sensitivity, a flexible structure, and a wide temperature range, and can be used in a variety of applications, particularly in space missions for human exploration.

  6. [Radiation protectors within the radiation safety system for extended duration exploration missions].

    PubMed

    Ushakov, I B; Vasin, M V

    2011-01-01

    Radiation environment in extended duration exploration missions is scrutinized in the context of the probability of the risks of deterministic and stochastic effects of radiation. Though the probability of severe radiation damage due to solar flare is very low, nonetheless it is requisite that the crew must be provided with appropriate, including pharmacological safeguards. The current nomenclature of radiation protectors composes short-term agents against acute radiation damage. Among the others, preparation B-190 is distinguished by particularly high effectiveness and universal action, and good tolerance even when organism is exposed to the extreme factors of space flight Regimen of B-290 therapy alone and with combination with aminothiol preparations have been developed to render treatment following multiple solar events. Effectiveness of radioprotectors can be increased substantially by local shielding of the abdomen and pelvis. The most promising nonspecific stimulators of total resistance of organism are riboxin (inosin) and combined preparation aminotetravit as well as vitamins tocopherol and retinol. Therapy combining B-190 with riboxin and aminotetravit is also under discussion. Cytokine neipogen is also viewed as a candidate agent for early therapy. Concern is raised about possible development of chronic oxidative stress in long-duration exploration missions. Highlighted is the significance of adequate nutrition supplemented with fresh vegetables as a source of the most valuable bioflavonoids. Antioxidants L-selenomethionine and melatonin proved their effectiveness against heavy nuclei of galactic radiation. An open issue is how to make natural antioxidants beneficial to oxidative stress control and attenuation of low-intensity galactic radiation.

  7. Compact and extended objects from self-interacting phantom fields

    NASA Astrophysics Data System (ADS)

    Dzhunushaliev, Vladimir; Folomeev, Vladimir; Makhmudov, Arislan; Urazalina, Ainur; Singleton, Douglas; Scott, John

    2016-07-01

    In this work, we investigate localized and extended objects for gravitating, self-interacting phantom fields. The phantom fields come from two scalar fields with a "wrong-sign" (negative) kinetic energy term in the Lagrangian. This study covers several solutions supported by these phantom fields: phantom balls, traversable wormholes, phantom cosmic strings, and "phantom" domain walls. These four systems are solved numerically, and we try to draw out general, interesting features in each case.

  8. Hawking radiation of a vector field and gravitational anomalies

    SciTech Connect

    Murata, Keiju; Miyamoto, Umpei

    2007-10-15

    Recently, the relation between Hawking radiation and gravitational anomalies has been used to estimate the flux of Hawking radiation for a large class of black objects. In this paper, we extend the formalism, originally proposed by Robinson and Wilczek, to the Hawking radiation of vector particles (photons). It is explicitly shown, with the Hamiltonian formalism, that the theory of an electromagnetic field on d-dimensional spherical black holes reduces to one of an infinite number of massive complex scalar fields on 2-dimensional spacetime, for which the usual anomaly-cancellation method is available. It is found that the total energy emitted from the horizon for the electromagnetic field is just (d-2) times that for a scalar field. The results support the picture that Hawking radiation can be regarded as an anomaly eliminator on horizons. Possible extensions and applications of the analysis are discussed.

  9. Interdigitated Extended Gate Field Effect Transistor Without Reference Electrode

    NASA Astrophysics Data System (ADS)

    Ali, Ghusoon M.

    2017-02-01

    An interdigitated extended gate field effect transistor (IEGFET) has been proposed as a modified pH sensor structure of an extended gate field effect transistor (EGFET). The reference electrode and the extended gate in the conventional device have been replaced by a single interdigitated extended gate. A metal-semiconductor-metal interdigitated extended gate containing two multi-finger Ni electrodes based on zinc oxide (ZnO) thin film as a pH-sensitive membrane. ZnO thin film was grown on a p-type Si (100) substrate by the sol-gel technique. The fabricated extended gate is connected to a commercial metal-oxide-semiconductor field-effect transistor device in CD4007UB. The experimental data show that this structure has real time and linear pH voltage and current sensitivities in a concentration range between pH 4 and 11. The voltage and current sensitivities are found to be about 22.4 mV/pH and 45 μA/pH, respectively. Reference electrode elimination makes the IEGFET device simple to fabricate, easy to carry out the measurements, needing a small volume of solution to test and suitable for disposable biosensor applications. Furthermore, this uncomplicated structure could be extended to fabricate multiple ions microsensors and lab-on-chip devices.

  10. An Iterative Phase-Space Explicit Discontinuous Galerkin Method for Stellar Radiative Transfer in Extended Atmospheres

    SciTech Connect

    de Almeida, V.F.

    2004-01-28

    A phase-space discontinuous Galerkin (PSDG) method is presented for the solution of stellar radiative transfer problems. It allows for greater adaptivity than competing methods without sacrificing generality. The method is extensively tested on a spherically symmetric, static, inverse-power-law scattering atmosphere. Results for different sizes of atmospheres and intensities of scattering agreed with asymptotic values. The exponentially decaying behavior of the radiative field in the diffusive-transparent transition region and the forward peaking behavior at the surface of extended atmospheres were accurately captured. The integrodifferential equation of radiation transfer is solved iteratively by alternating between the radiative pressure equation and the original equation with the integral term treated as an energy density source term. In each iteration, the equations are solved via an explicit, flux-conserving, discontinuous Galerkin method. Finite elements are ordered in wave fronts perpendicularly to the characteristic curves so that elemental linear algebraic systems are solved quickly by sweeping the phase space element by element. Two implementations of a diffusive boundary condition at the origin are demonstrated wherein the finite discontinuity in the radiative intensity is accurately captured by the proposed method. This allows for a consistent mechanism to preserve photon luminosity. The method was proved to be robust and fast, and a case is made for the adequacy of parallel processing. In addition to classical two-dimensional plots, results of normalized radiative intensity were mapped onto a log-polar surface exhibiting all distinguishing features of the problem studied.

  11. Extended depth of field imaging for high speed object analysis

    NASA Technical Reports Server (NTRS)

    Ortyn, William (Inventor); Basiji, David (Inventor); Frost, Keith (Inventor); Liang, Luchuan (Inventor); Bauer, Richard (Inventor); Hall, Brian (Inventor); Perry, David (Inventor)

    2011-01-01

    A high speed, high-resolution flow imaging system is modified to achieve extended depth of field imaging. An optical distortion element is introduced into the flow imaging system. Light from an object, such as a cell, is distorted by the distortion element, such that a point spread function (PSF) of the imaging system is invariant across an extended depth of field. The distorted light is spectrally dispersed, and the dispersed light is used to simultaneously generate a plurality of images. The images are detected, and image processing is used to enhance the detected images by compensating for the distortion, to achieve extended depth of field images of the object. The post image processing preferably involves de-convolution, and requires knowledge of the PSF of the imaging system, as modified by the optical distortion element.

  12. Two-field radiation hydrodynamics in n spatial dimensions

    NASA Astrophysics Data System (ADS)

    Larecki, Wieslaw; Banach, Zbigniew

    2016-03-01

    The two-field radiation hydrodynamics in n spatial dimensions is derived from the kinetic theory of radiation. Both the full-moment (frequency-independent) and spectral (frequency-dependent) formulations of radiation hydrodynamics are considered. The derivation is based on the entropy principle of extended thermodynamics of gases. In the case of the full-moment hydrodynamics, the formulation of the entropy principle introduced by Boillat and Ruggeri (1997 Contin. Mech. Thermodyn. 9 205) is adapted and this suffices to determine the radiation pressure tensor. In the full-moment formulation, the equations of radiation hydrodynamics take the same form for all possible types of radiation statistics. In the spectral formulation, the different radiation pressure tensors are assigned to Bose-Einstein, Fermi-Dirac and Maxwell-Boltzmann statistics, and consequently the different hydrodynamic equations are obtained for each of those statistics types. In order to derive the equations of the spectral radiation hydrodynamics, the relations for the radiation pressure tensor implied by the entropy principle must be supplemented by the additional conditions. Considering the limit of small heat flux, we arrive at the linearized equations of radiation hydrodynamics which assume the same form in both the full-moment and spectral formulations.

  13. Harmonic undulator radiations with constant magnetic field

    NASA Astrophysics Data System (ADS)

    Jeevakhan, Hussain; Mishra, G.

    2015-01-01

    Harmonic undulators has been analysed in the presence of constant magnetic field along the direction of main undulator field. The spectrum modifications in harmonic undulator radiations and intensity degradation as a function of constant magnetic field magnitude at fundamental and third harmonics have been evaluated with a numerical integration method and generalised Bessel function. The role of harmonic field to overcome the intensity reduction due to constant magnetic field and energy spread in electron beam has also been demonstrated.

  14. Radiated fields from an electromagnetic pulse simulator

    NASA Astrophysics Data System (ADS)

    Pelletier, M.; Delisle, G. Y.; Kashyap, S.

    Simulators of electromagnetic pulses allow generation within a limited time of very high-intensity fields such as those produced in a nuclear explosion. These fields can be radiated out of the test zone at a lower but nevertheless significant level; if the intensity of these fields is sufficiently high, damage to humans and electronic equipment can result. An evaluation of the potential danger of these simulator emissions requires knowledge of the amplitude, duration, and the energy of the radiated impulses. A technique is presented for calculating the fields radiated by a parallel-plane electromagnetic pulse simulator. The same method can also be applied to a rhombic type simulator. Sample numerical results are presented along with the calculations of the energy and power density and a discussion of the formation of the field in the frequency domain.

  15. Extended depth of field imaging at 94 GHz

    NASA Astrophysics Data System (ADS)

    Mait, Joseph N.; Wikner, David A.; Mirotznik, Mark S.; van der Gracht, Joseph; Behrmann, Gregory P.; Good, Brandon L.; Mathews, Scott A.

    2008-04-01

    We describe a computational imaging technique to extend the depth-of field of a 94-GHz imaging system. The technique uses a cubic phase element in the pupil plane of the system to render system operation relatively insensitive to object distance. However, the cubic phase element also introduces aberrations but, since these are fixed and known, we remove them using post-detection signal processing. We present experimental results that validate system performance and indicate a greater than four-fold increase in depth-of-field from 17" to greater than 68".

  16. Extended time-dependent mean-field approximation

    SciTech Connect

    Portes, D.A. Jr. |; Kodama, T.; de Toledo Piza, A.F.

    1996-09-01

    The time-dependent mean-field approximation for two dynamically coupled subsystems is extended to include correlation effects between the subsystems, allowing for decorrelation processes to develop in the reduced density matrices. The extended scheme is formulated in terms of the truncation to {ital M} terms of the Schmidt decomposition of the full density matrix. This {ital M} natural orbitals truncation scheme is compared to the exact numerical solution for a system of two coupled anharmonic oscillators in a factorized initial state. It is found that the approximation {ital M}=3 gives a good approximation to the exact results over several characteristic times of the system. {copyright} {ital 1996 The American Physical Society.}

  17. The radiation field in multilayer media.

    NASA Astrophysics Data System (ADS)

    Viik, T.

    In the atmospheres of planets and stars there may exist sufficiently thick plane-parallel layers in which the optical properties of the medium, e.g. the albedo of single scattering, the phase function etc., are nearly constant. If we use finite difference, differential or integral methods to find the radiation field in such a layer, we have to integrate the radiative transfer equation in short steps due to the inner nature of these methods.

  18. The NASA High Intensity Radiated Fields Laboratory

    NASA Technical Reports Server (NTRS)

    Williams, Reuben A.

    1997-01-01

    High Intensity Radiated Fields (HIRF) are the result of a multitude of intentional and nonintentional electromagnetic sources that currently exists in the world. Many of today's digital systems are susceptible to electronic upset if subjected to certain electromagnetic environments (EME). Modern aerospace designers and manufacturers increasingly rely on sophisticated digital electronic systems to provide critical flight control in both military, commercial, and general aviation aircraft. In an effort to understand and emulate the undesired environment that high energy RF provides modern electronics, the Electromagnetics Research Branch (ERB) of the Flight Electronics and Technology Division (FETD) conducts research on RF and microwave measurement methods related to the understanding of HIRF. In the High Intensity Radiated Fields Laboratory, the effects of high energy radiating electromagnetic fields on avionics and electronic systems are tested and studied.

  19. Compressive Passive Millimeter Wave Imaging with Extended Depth of Field

    DTIC Science & Technology

    2012-01-01

    Over the past several years, imaging using millimeter wave ( mmW ) and terahertz technology has gained a lot of interest [1], [2], [3]. This interest...weapons are clearly detected in the mmW image. Recently, in [3], Mait et al. presented a computational imaging method to extend the depth-of-field of a...passive mmW imaging sys- tem. The method uses a cubic phase element in the pupil plane of the system to render system operation relatively insensitive

  20. Numerical results for extended field method applications. [thin plates

    NASA Technical Reports Server (NTRS)

    Donaldson, B. K.; Chander, S.

    1973-01-01

    This paper presents the numerical results obtained when a new method of analysis, called the extended field method, was applied to several thin plate problems including one with non-rectangular geometry, and one problem involving both beams and a plate. The numerical results show that the quality of the single plate solutions was satisfactory for all cases except those involving a freely deflecting plate corner. The results for the beam and plate structure were satisfactory even though the structure had a freely deflecting corner.

  1. Quantum phenomena and the zeropoint radiation field

    NASA Astrophysics Data System (ADS)

    de La Peña, L.; Cetto, A. M.

    1994-06-01

    The stationary solutions for a bound electron immersed in the random zeropoint radiation field of stochastic electrodynamics are studied, under the assumption that the characteristic Fourier frequencies of these solutions are not random. Under this assumption, the response of the particle to the field is linear and does not mix frequencies, irrespectively of the form of the binding force; the fluctuations of the random field fix the scale of the response. The effective radiation field that supports the stationary states of motion is no longer the free vacuum field, but a modified form of it with new statistical properties. The theory is expressed naturally in terms of matrices (or operators), and it leads to the Heisenberg equations and the Hilbert space formalism of quantum mechanics in the radiationless approximation. The connection with the poissonian formulation of stochastic electrodynamics is also established. At the end we briefly discuss a few important aspects of quantum mechanics which the present theory helps to clarify.

  2. The Average Field Approximation for Almost Bosonic Extended Anyons

    NASA Astrophysics Data System (ADS)

    Lundholm, Douglas; Rougerie, Nicolas

    2015-12-01

    Anyons are 2D or 1D quantum particles with intermediate statistics, interpolating between bosons and fermions. We study the ground state of a large number N of 2D anyons, in a scaling limit where the statistics parameter α is proportional to N ^{-1} when N→ ∞ . This means that the statistics is seen as a "perturbation from the bosonic end". We model this situation in the magnetic gauge picture by bosons interacting through long-range magnetic potentials. We assume that these effective statistical gauge potentials are generated by magnetic charges carried by each particle, smeared over discs of radius R (extended anyons). Our method allows to take R→ 0 not too fast at the same time as N→ ∞ . In this limit we rigorously justify the so-called "average field approximation": the particles behave like independent, identically distributed bosons interacting via a self-consistent magnetic field.

  3. Radiation reaction in high-intensity fields

    NASA Astrophysics Data System (ADS)

    Seto, Keita

    2015-10-01

    Since the development of a radiating electron model by Dirac in 1938 [P. A. M. Dirac, Proc. R. Soc. Lond. A 167, 148 (1938)], many authors have tried to reformulate this model of the so-called "radiation reaction". Recently, this effect has become important in ultra-intense laser-electron (plasma) interactions. In our recent research, we found a way of stabilizing the radiation reaction by quantum electrodynamics (QED) vacuum fluctuation [K Seto et al., Prog. Theor. Exp. Phys. 2014, 043A01 (2014); K. Seto, Prog. Theor. Exp. Phys. 2015, 023A01 (2015)]. On the other hand, the modification of the radiated field by highly intense incoming laser fields should be taken into account when the laser intensity is higher than 10^{22} W/cm2, which could be achieved by next-generation ultra-short-pulse 10 PW lasers, like the ones under construction for the ELI-NP facility. In this paper, I propose a running charge-mass method for the description of the QED-based synchrotron radiation by high-intensity external fields with stabilization by the QED vacuum fluctuation as an extension from the model by Dirac.

  4. Cosmological magnetic fields from inflation in extended electromagnetism

    SciTech Connect

    Beltran Jimenez, Jose; Maroto, Antonio L.

    2011-01-15

    In this work we consider an extended electromagnetic theory in which the scalar state which is usually eliminated by means of the Lorenz condition is allowed to propagate. This state has been shown to generate a small cosmological constant in the context of standard inflationary cosmology. Here we show that the usual Lorenz gauge-breaking term now plays the role of an effective electromagnetic current. Such a current is generated during inflation from quantum fluctuations and gives rise to a stochastic effective charge density distribution. Because of the high electric conductivity of the cosmic plasma after inflation, the electric charge density generates currents which give rise to both vorticity and magnetic fields on sub-Hubble scales. Present upper limits on vorticity coming from temperature anisotropies of the CMB are translated into lower limits on the present value of cosmic magnetic fields. We find that, for a nearly scale invariant vorticity spectrum, magnetic fields B{sub {lambda}>}10{sup -12} G are typically generated with coherence lengths ranging from subgalactic scales up to the present Hubble radius. Those fields could act as seeds for a galactic dynamo or even account for observations just by collapse and differential rotation of the protogalactic cloud.

  5. Extending methods: using Bourdieu's field analysis to further investigate taste

    NASA Astrophysics Data System (ADS)

    Schindel Dimick, Alexandra

    2015-06-01

    In this commentary on Per Anderhag, Per-Olof Wickman and Karim Hamza's article Signs of taste for science, I consider how their study is situated within the concern for the role of science education in the social and cultural production of inequality. Their article provides a finely detailed methodology for analyzing the constitution of taste within science education classrooms. Nevertheless, because the authors' socially situated methodology draws upon Bourdieu's theories, it seems equally important to extend these methods to consider how and why students make particular distinctions within a relational context—a key aspect of Bourdieu's theory of cultural production. By situating the constitution of taste within Bourdieu's field analysis, researchers can explore the ways in which students' tastes and social positionings are established and transformed through time, space, place, and their ability to navigate the field. I describe the process of field analysis in relation to the authors' paper and suggest that combining the authors' methods with a field analysis can provide a strong methodological and analytical framework in which theory and methods combine to create a detailed understanding of students' interest in relation to their context.

  6. Extending radiative transfer models by use of Bayes rule. [in atmospheric science

    NASA Technical Reports Server (NTRS)

    Whitney, C.

    1977-01-01

    This paper presents a procedure that extends some existing radiative transfer modeling techniques to problems in atmospheric science where curvature and layering of the medium and dynamic range and angular resolution of the signal are important. Example problems include twilight and limb scan simulations. Techniques that are extended include successive orders of scattering, matrix operator, doubling, Gauss-Seidel iteration, discrete ordinates and spherical harmonics. The procedure for extending them is based on Bayes' rule from probability theory.

  7. Potential theoretic methods for far field sound radiation calculations

    NASA Technical Reports Server (NTRS)

    Hariharan, S. I.; Stenger, Edward J.; Scott, J. R.

    1995-01-01

    In the area of computational acoustics, procedures which accurately predict the far-field sound radiation are much sought after. A systematic development of such procedures are found in a sequence of papers by Atassi. The method presented here is an alternate approach to predicting far field sound based on simple layer potential theoretic methods. The main advantages of this method are: it requires only a simple free space Green's function, it can accommodate arbitrary shapes of Kirchoff surfaces, and is readily extendable to three-dimensional problems. Moreover, the procedure presented here, though tested for unsteady lifting airfoil problems, can easily be adapted to other areas of interest, such as jet noise radiation problems. Results are presented for lifting airfoil problems and comparisons are made with the results reported by Atassi. Direct comparisons are also made for the flat plate case.

  8. Dynamics of Cometary Dust Particles in Electromagnetic Radiation Fields

    NASA Astrophysics Data System (ADS)

    Herranen, Joonas; Markkanen, Johannes; Penttilä, Antti; Muinonen, Karri

    2016-10-01

    The formation of cometary dust tails and comae is based on solar radiation pressure. The pressure effects of electromagnetic radiation were originally conceptualized in Kepler's observations of the tails of comets and formulated mathematically by Maxwell in 1873. Today, the dynamics of cometary dust are known to be governed by gravity, electromagnetic forces, drag, solar wind, and solar radiation pressure.Solar radiation pressure has its roots in absorption, emission, and scattering of electromagnetic radiation. Due to modern advances in so-called integral equation methods in electromagnetics, a new approach of studying the effect of radiation pressure on cometary dust dynamics can be constructed. We solve the forces and torques due to radiation pressure for an arbitrarily shaped dust particle using volume integral equation methods.We then present a framework for solving the equations of motion of cometary dust particles due to radiative interactions. The solution is studied in a simplified cometary environment, where the radiative effects are studied at different orbits. The rotational and translational equations of motion are solved directly using a quaternion-based integrator. The rotational and translational equations of motion affect dust particle alignment and concentration. This is seen in the polarization of the coma. Thus, our direct dynamical approach can be used in modelling the observed imaging photo-polarimetry of the coma.In future studies, the integrator can be further extended to an exemplary comet environment, taking into account the drag, and the electric and magnetic fields. This enables us to study the dynamics of a single cometary dust particle based on fundamental physics.Acknowledgments. Research supported, in part, bythe European Research Council (ERC, grant Nr. 320773).

  9. Formation of secondary radiation fields at NICA

    NASA Astrophysics Data System (ADS)

    Timoshenko, G.; Paraipan, M.

    2009-09-01

    The crucial points of a radiation shielding design for a relativistic heavy ion accelerator are the source term problem, neutron fluence and dose attenuation characteristics of the shielding. Simulations of the radiation shielding for JINR's Nuclotron-Based Ion Facility (NICA) project were carried out using the GEANT4 code. Some regularities in the secondary neutron field generation at the 4.5 GeV/n uranium beam interaction with thick targets are discussed. Neutron attenuation by the ordinary concrete shielding of NICA was considered as well.

  10. Radiation Effects on Current Field Programmable Technologies

    NASA Technical Reports Server (NTRS)

    Katz, R.; LaBel, K.; Wang, J. J.; Cronquist, B.; Koga, R.; Penzin, S.; Swift, G.

    1997-01-01

    Manufacturers of field programmable gate arrays (FPGAS) take different technological and architectural approaches that directly affect radiation performance. Similar y technological and architectural features are used in related technologies such as programmable substrates and quick-turn application specific integrated circuits (ASICs). After analyzing current technologies and architectures and their radiation-effects implications, this paper includes extensive test data quantifying various devices total dose and single event susceptibilities, including performance degradation effects and temporary or permanent re-configuration faults. Test results will concentrate on recent technologies being used in space flight electronic systems and those being developed for use in the near term. This paper will provide the first extensive study of various configuration memories used in programmable devices. Radiation performance limits and their impacts will be discussed for each design. In addition, the interplay between device scaling, process, bias voltage, design, and architecture will be explored. Lastly, areas of ongoing research will be discussed.

  11. Haemopoietic cell renewal in radiation fields

    NASA Astrophysics Data System (ADS)

    Fliedner, T. M.; Nothdurft, W.; Tibken, B.; Hofer, E.; Weiss, M.; Kindler, H.

    1994-10-01

    Space flight activities are inevitably associated with a chronic exposure of astronauts to a complex mixture of ionising radiation. Although no acute radiation consequences are to be expected as a rule, the possibility of Solar Particle Events (SPE) associated with relatively high doses of radiation (1 or more Gray) cannot be excluded. It is the responsibility of physicians in charge of the health of astronauts to evaluate before, during and after space flight activities the functional status of haemopoietic cell renewal. Chronic low level exposure of dogs indicate that daily gamma-exposure doses below about 2 cGy are tolerated for several years as far as blood cell concentrations are concerned. However, the stem cell pool may be severely affected. The maintenance of sufficient blood cell counts is possible only through increased cell production to compensate for the radiation inflicted excess cell loss. This behaviour of haemopoietic cell renewal during chronic low level exposure can be simulated by bioengineering models of granulocytopoiesis. It is possible to define a ``turbulence region'' for cell loss rates, below which an prolonged adaptation to increased radiation fields can be expected to be tolerated. On the basis of these experimental results, it is recommended to develop new biological indicators to monitor haemopoietic cell renewal at the level of the stem cell pool using blood stem cells in addition to the determination of cytokine concentrations in the serum (and other novel approaches). To prepare for unexpected haemopoietic effects during prolonged space missions, research should be increased to modify the radiation sensitivity of haemopoietic stem cells (for instance by the application of certain regulatory molecules). In addition, a ``blood stem cell bank'' might be established for the autologous storage of stem cells and for use in space activities keeping them in a radiation protected container.

  12. Plasma wake field XUV radiation source

    DOEpatents

    Prono, Daniel S.; Jones, Michael E.

    1997-01-01

    A XUV radiation source uses an interaction of electron beam pulses with a gas to create a plasma radiator. A flowing gas system (10) defines a circulation loop (12) with a device (14), such as a high pressure pump or the like, for circulating the gas. A nozzle or jet (16) produces a sonic atmospheric pressure flow and increases the density of the gas for interacting with an electron beam. An electron beam is formed by a conventional radio frequency (rf) accelerator (26) and electron pulses are conventionally formed by a beam buncher (28). The rf energy is thus converted to electron beam energy, the beam energy is used to create and then thermalize an atmospheric density flowing gas to a fully ionized plasma by interaction of beam pulses with the plasma wake field, and the energetic plasma then loses energy by line radiation at XUV wavelengths Collection and focusing optics (18) are used to collect XUV radiation emitted as line radiation when the high energy density plasma loses energy that was transferred from the electron beam pulses to the plasma.

  13. The Stellar Extreme-Ultraviolet Radiation Field

    NASA Astrophysics Data System (ADS)

    Vallerga, John

    1998-04-01

    The local extreme ultraviolet (EUV) radiation field from stellar sources has been determined by combining the EUV spectra of 54 stars, taken with the spectrometers aboard the Extreme Ultraviolet Explorer satellite. The resultant spectrum over the range 70-730 Å is estimated to be 95% complete above 400 Å and 90% complete above 200 Å. The flux contributed by two B stars and three hot white dwarfs dominate the spectrum except at the shortest wavelengths, where an assortment of EUV source types contribute. The high electron densities measured toward nearby stars can be accounted for by photoionization from this radiation field, but the spectrum is too soft to explain the overionization of helium with respect to hydrogen recently measure in the Local Cloud.

  14. Radiative instabilities in sheared magnetic field

    NASA Technical Reports Server (NTRS)

    Drake, J. F.; Sparks, L.; Van Hoven, G.

    1988-01-01

    The structure and growth rate of the radiative instability in a sheared magnetic field B have been calculated analytically using the Braginskii fluid equations. In a shear layer, temperature and density perturbations are linked by the propagation of sound waves parallel to the local magnetic field. As a consequence, density clumping or condensation plays an important role in driving the instability. Parallel thermal conduction localizes the mode to a narrow layer where K(parallel) is small and stabilizes short wavelengths k larger-than(c) where k(c) depends on the local radiation and conduction rates. Thermal coupling to ions also limits the width of the unstable spectrum. It is shown that a broad spectrum of modes is typically unstable in tokamak edge plasmas and it is argued that this instability is sufficiently robust to drive the large-amplitude density fluctuations often measured there.

  15. Cellular response to modulated radiation fields

    NASA Astrophysics Data System (ADS)

    Claridge Mackonis, E.; Suchowerska, N.; Zhang, M.; Ebert, M.; McKenzie, D. R.; Jackson, M.

    2007-09-01

    Cell survival following exposure to spatially modulated beams, as created by intensity-modulated radiotherapy (IMRT), is investigated. In vitro experiments were performed using malignant melanoma cells (MM576) exposed to a therapeutic megavoltage photon beam. We compared cell survival in modulated fields with cell survival in uniform control fields. Three different spatial modulations of the field were used: a control 'uniform' field in which all cells in a flask were uniformly exposed; a 'quarter' field in which 25% of cells at one end of the flask were exposed and a 'striped' field in which 25% of cells were exposed in three parallel stripes. The cell survival in both the shielded and unshielded regions of the modulated fields, as determined by a clonogenic assay, were compared to the cell survival in the uniform field. We have distinguished three ways in which cell survival is influenced by the fate of neighbouring cells. The first of these (type I effect) is the previously reported classical Bystander effect, where cell survival is reduced when communicating with irradiated cells. We find two new types of Bystander effect. The type II effect is an observed increase in cell survival when nearby cells receive a lethal dose. The type III effect is an increase in the survival of cells receiving a high dose of radiation, when nearby cells receive a low dose. These observations of the Bystander effects emphasize the need for improved radiobiological models, which include communicated effects and account for the effects of modulated dose distribution.

  16. Limited-field radiation for bifocal germinoma

    SciTech Connect

    Lafay-Cousin, Lucie . E-mail: lucie.lafay-cousin@sickkids.ca; Millar, Barbara-Ann; Mabbott, Donald; Spiegler, Brenda; Drake, Jim; Bartels, Ute; Huang, Annie; Bouffet, Eric

    2006-06-01

    Purpose: To report the incidence, characteristics, treatment, and outcomes of bifocal germinomas treated with chemotherapy followed by focal radiation. Methods and Materials: This was a retrospective review. Inclusion criteria included radiologic diagnosis of bifocal germinoma involving the pineal and neurohypophyseal region, no evidence of dissemination on spinal MRI, negative results from cerebrospinal fluid cytologic evaluation, and negative tumor markers. Results: Between 1995 and 2004, 6 patients (5 male, 1 female; median age, 12.8 years) fulfilled the inclusion criteria. All had symptoms of diabetes insipidus at presentation. On MRI, 4 patients had a pineal and suprasellar mass, and 2 had a pineal mass associated with abnormal neurohypophyseal enhancement. All patients received chemotherapy followed by limited-field radiation and achieved complete remission after chemotherapy. The radiation field involved the whole ventricular system (range, 2,400-4,000 cGy) with or without a boost to the primary lesions. All patients remain in complete remission at a median follow-up of 48.1 months (range, 9-73.4 months). Conclusions: This experience suggests that bifocal germinoma can be considered a locoregional rather than a metastatic disease. Chemotherapy and focal radiotherapy might be sufficient to provide excellent outcomes. Staging refinement with new diagnostic tools will likely increase the incidence of the entity.

  17. Virtual radiation fields for ALARA determination

    SciTech Connect

    Knight, T.W.

    1995-12-31

    As computing power has increased, so too has the ability to model and simulate complex systems and processes. In addition, virtual reality technology has made it possible to visualize and understand many complex scientific and engineering problems. For this reason, a virtual dosimetry program called Virtual Radiation Fields (VRF) is developed to model radiation dose rate and cumulative dose to a receptor operating in a virtual radiation environment. With the design and testing of many facilities and products taking place in the virtual world, this program facilitates the concurrent consideration of radiological concerns during the design process. Three-dimensional (3D) graphical presentation of the radiation environment is made possible through the use of IGRIP, a graphical modeling program developed by Deneb Robotics, Inc. The VRF simulation program was designed to model and display a virtual dosimeter. As a demonstration of the program`s capability, the Hanford tank, C-106, was modeled to predict radiation doses to robotic equipment used to remove radioactive waste from the tank. To validate VRF dose predictions, comparison was made with reported values for tank C-106, which showed agreement to within 0.5%. Graphical information is presented regarding the 3D dose rate variation inside the tank. Cumulative dose predictions were made for the cleanup operations of tank C-106. A four-dimensional dose rate map generated by VRF was used to model the dose rate not only in 3D space but also as a function of the amount of waste remaining in the tank. This allowed VRF to predict dose rate at any stage in the waste removal process for an accurate simulation of the radiological conditions throughout the tank cleanup procedure.

  18. Hybrid Imaging for Extended Depth of Field Microscopy

    NASA Astrophysics Data System (ADS)

    Zahreddine, Ramzi Nicholas

    An inverse relationship exists in optical systems between the depth of field (DOF) and the minimum resolvable feature size. This trade-off is especially detrimental in high numerical aperture microscopy systems where resolution is pushed to the diffraction limit resulting in a DOF on the order of 500 nm. Many biological structures and processes of interest span over micron scales resulting in significant blurring during imaging. This thesis explores a two-step computational imaging technique known as hybrid imaging to create extended DOF (EDF) microscopy systems with minimal sacrifice in resolution. In the first step a mask is inserted at the pupil plane of the microscope to create a focus invariant system over 10 times the traditional DOF, albeit with reduced contrast. In the second step the contrast is restored via deconvolution. Several EDF pupil masks from the literature are quantitatively compared in the context of biological microscopy. From this analysis a new mask is proposed, the incoherently partitioned pupil with binary phase modulation (IPP-BPM), that combines the most advantageous properties from the literature. Total variation regularized deconvolution models are derived for the various noise conditions and detectors commonly used in biological microscopy. State of the art algorithms for efficiently solving the deconvolution problem are analyzed for speed, accuracy, and ease of use. The IPP-BPM mask is compared with the literature and shown to have the highest signal-to-noise ratio and lowest mean square error post-processing. A prototype of the IPP-BPM mask is fabricated using a combination of 3D femtosecond glass etching and standard lithography techniques. The mask is compared against theory and demonstrated in biological imaging applications.

  19. Observations of the diffuse UV radiation field

    NASA Technical Reports Server (NTRS)

    Murthy, Jayant; Henry, R. C.; Feldman, P. D.; Tennyson, P. D.

    1989-01-01

    Spectra are presented for the diffuse UV radiation field between 1250 to 3100 A from eight different regions of the sky, which were obtained with the Johns Hopkins UVX experiment. UVX flew aboard the Space Shuttle Columbia (STS-61C) in January 1986 as part of the Get-Away Special project. The experiment consisted of two 1/4 m Ebert-Fastie spectrometers, covering the spectral range 1250 to 1700 A at 17 A resolution and 1600 to 3100 A at 27 A resolution, respectively, with a field of view of 4 x .25 deg, sufficiently small to pick out regions of the sky with no stars in the line of sight. Values were found for the diffuse cosmic background ranging in intensity from 300 to 900 photons/sq cm/sec/sr/A. The cosmic background is spectrally flat from 1250 to 3100 A, within the uncertainties of each spectrometer. The zodiacal light begins to play a significant role in the diffuse radiation field above 2000 A, and its brightness was determined relative to the solar emission. Observed brightnesses of the zodiacal light in the UV remain almost constant with ecliptic latitude, unlike the declining visible brightnesses, possibly indicating that those (smaller) grains responsible for the UV scattering have a much more uniform distribution with distance from the ecliptic plane than do those grains responsible for the visible scattering.

  20. Extending generalized Kubelka-Munk to three-dimensional radiative transfer.

    PubMed

    Sandoval, Christopher; Kim, Arnold D

    2015-08-10

    The generalized Kubelka-Munk (gKM) approximation is a linear transformation of the double spherical harmonics of order one (DP1) approximation of the radiative transfer equation. Here, we extend the gKM approximation to study problems in three-dimensional radiative transfer. In particular, we derive the gKM approximation for the problem of collimated beam propagation and scattering in a plane-parallel slab composed of a uniform absorbing and scattering medium. The result is an 8×8 system of partial differential equations that is much easier to solve than the radiative transfer equation. We compare the solutions of the gKM approximation with Monte Carlo simulations of the radiative transfer equation to identify the range of validity for this approximation. We find that the gKM approximation is accurate for isotropic scattering media that are sufficiently thick and much less accurate for anisotropic, forward-peaked scattering media.

  1. Excitation of magnetization using a modulated radiation damping field.

    PubMed

    Walls, Jamie D; Huang, Susie Y; Lin, Yung-Ya

    2006-10-12

    In this work, pulsed-field gradients are used to modulate the radiation damping field generated by the detection coil in an NMR experiment in order that spins with significantly different chemical shifts can affect one another via the radiation damping field. Experiments performed on solutions of acetone/water and acetone/DMSO/water demonstrate that spins with chemical shift differences much greater than the effective radiation damping field strength can still be coupled by modulating the radiation damping field. Implications for applications in high-field NMR and for developing sensitive magnetization detectors are discussed.

  2. Radiative corrections from heavy fast-roll fields during inflation

    SciTech Connect

    Jain, Rajeev Kumar; Sandora, McCullen; Sloth, Martin S.

    2015-06-09

    We investigate radiative corrections to the inflaton potential from heavy fields undergoing a fast-roll phase transition. We find that a logarithmic one-loop correction to the inflaton potential involving this field can induce a temporary running of the spectral index. The induced running can be a short burst of strong running, which may be related to the observed anomalies on large scales in the cosmic microwave spectrum, or extend over many e-folds, sustaining an effectively constant running to be searched for in the future. We implement this in a general class of models, where effects are mediated through a heavy messenger field sitting in its minimum. Interestingly, within the present framework it is a generic outcome that a large running implies a small field model with a vanishing tensor-to-scalar ratio, circumventing the normal expectation that small field models typically lead to an unobservably small running of the spectral index. An observable level of tensor modes can also be accommodated, but, surprisingly, this requires running to be induced by a curvaton. If upcoming observations are consistent with a small tensor-to-scalar ratio as predicted by small field models of inflation, then the present study serves as an explicit example contrary to the general expectation that the running will be unobservable.

  3. Radiative corrections from heavy fast-roll fields during inflation

    SciTech Connect

    Jain, Rajeev Kumar; Sandora, McCullen; Sloth, Martin S. E-mail: sandora@cp3.dias.sdu.dk

    2015-06-01

    We investigate radiative corrections to the inflaton potential from heavy fields undergoing a fast-roll phase transition. We find that a logarithmic one-loop correction to the inflaton potential involving this field can induce a temporary running of the spectral index. The induced running can be a short burst of strong running, which may be related to the observed anomalies on large scales in the cosmic microwave spectrum, or extend over many e-folds, sustaining an effectively constant running to be searched for in the future. We implement this in a general class of models, where effects are mediated through a heavy messenger field sitting in its minimum. Interestingly, within the present framework it is a generic outcome that a large running implies a small field model with a vanishing tensor-to-scalar ratio, circumventing the normal expectation that small field models typically lead to an unobservably small running of the spectral index. An observable level of tensor modes can also be accommodated, but, surprisingly, this requires running to be induced by a curvaton. If upcoming observations are consistent with a small tensor-to-scalar ratio as predicted by small field models of inflation, then the present study serves as an explicit example contrary to the general expectation that the running will be unobservable.

  4. Self-quartic interaction for a scalar field in an extended DFR noncommutative space-time

    NASA Astrophysics Data System (ADS)

    Abreu, Everton M. C.; Neves, M. J.

    2014-07-01

    The framework of Dopliche-Fredenhagen-Roberts (DFR) for a noncommutative (NC) space-time is considered as an alternative approach to study the NC space-time of the early Universe. Concerning this formalism, the NC constant parameter, θ, is promoted to coordinate of the space-time and consequently we can describe a field theory in a space-time with extra-dimensions. We will see that there is a canonical momentum associated with this new coordinate in which the effects of a new physics can emerge in the propagation of the fields along the extra-dimensions. The Fourier space of this framework is automatically extended by the addition of the new momenta components. The main concept that we would like to emphasize from the outset is that the formalism demonstrated here will not be constructed by introducing a NC parameter in the system, as usual. It will be generated naturally from an already NC space. We will review that when the components of the new momentum are zero, the (extended) DFR approach is reduced to the usual (canonical) NC case, in which θ is an antisymmetric constant matrix. In this work we will study a scalar field action with self-quartic interaction ϕ4⋆ defined in the DFR NC space-time. We will obtain the Feynman rules in the Fourier space for the scalar propagator and vertex of the model. With these rules we are able to build the radiative corrections to one loop order of the model propagator. The consequences of the NC scale, as well as the propagation of the field in extra-dimensions, will be analyzed in the ultraviolet divergences scenario. We will investigate about the actual possibility that this kμν conjugate momentum has the property of healing the combination of IR/UV divergences that emerges in this recently new NC spacetime quantum field theory.

  5. Temperature field for radiative tomato peeling

    NASA Astrophysics Data System (ADS)

    Cuccurullo, G.; Giordano, L.

    2017-01-01

    Nowadays peeling of tomatoes is performed by using steam or lye, which are expensive and polluting techniques, thus sustainable alternatives are searched for dry peeling and, among that, radiative heating seems to be a fairly promising method. This paper aims to speed up the prediction of surface temperatures useful for realizing dry-peeling, thus a 1D-analytical model for the unsteady temperature field in a rotating tomato exposed to a radiative heating source is presented. Since only short times are of interest for the problem at hand, the model involves a semi-infinite slab cooled by convective heat transfer while heated by a pulsating heat source. The model being linear, the solution is derived following the Laplace Transform method. A 3D finite element model of the rotating tomato is introduced as well in order to validate the analytical solution. A satisfactory agreement is attained. Therefore, two different ways to predict the onset of the peeling conditions are available which can be of help for proper design of peeling plants. Particular attention is paid to study surface temperature uniformity, that being a critical parameter for realizing an easy tomato peeling.

  6. Suppression of sound radiation to far field of near-field acoustic communication system using evanescent sound field

    NASA Astrophysics Data System (ADS)

    Fujii, Ayaka; Wakatsuki, Naoto; Mizutani, Koichi

    2016-01-01

    extended. Additionally, we designed a sound insulator so as to realize a similar distribution of the particle velocity to that obtained using the optimized window function. Sound radiation was suppressed using a sound insulator put above the vibrating surface in the simulation using the three-dimensional finite element method. On the basis of this finding, it was suggested that near-field acoustic communication which suppressed sound radiation can be realized by applying the optimized window function to the particle velocity field.

  7. Measurement of radiative capture resonance energies with an extended gas target

    NASA Astrophysics Data System (ADS)

    Hutcheon, D. A.; Ruiz, C.; Fallis, J.; D'Auria, J. M.; Davids, B.; Hager, U.; Martin, L.; Ottewell, D. F.; Reeve, S.; Rojas, A.

    2012-10-01

    The DRAGON facility for the study of radiative capture reactions has an extended gas target, surrounded by an array of BGO detectors. The distribution of detected gamma rays amongst the segmented array permits an estimate of the reaction position and consequently of the resonance energy. We report a study of the technique, using the 24Mg(p, γ)25Al reaction. Energy determination to better than 0.5% has been demonstrated.

  8. Vacuum radiation induced by time dependent electric field

    NASA Astrophysics Data System (ADS)

    Zhang, Bo; Zhang, Zhi-meng; Hong, Wei; He, Shu-Kai; Teng, Jian; Gu, Yu-qiu

    2017-04-01

    Many predictions of new phenomena given by strong field quantum electrodynamics (SFQED) will be tested on next generation multi-petawatt laser facilities in the near future. These new phenomena are basis to understand physics in extremely strong electromagnetic fields therefore have attracted wide research interest. Here we discuss a new SFQED phenomenon that is named as vacuum radiation. In vacuum radiation, a virtual electron loop obtain energy from time dependent external electric field and radiate an entangled photon pair. Features of vacuum radiation in a locally time dependent electric field including spectrum, characteristic temperature, production rate and power are given.

  9. Electromagnetic field radiation model for lightning strokes to tall structures

    SciTech Connect

    Motoyama, H.; Janischewskyj, W.; Hussein, A.M.; Chisholm, W.A.; Chang, J.S.; Rusan, R.

    1996-07-01

    This paper describes observation and analysis of electromagnetic field radiation from lightning strokes to tall structures. Electromagnetic field waveforms and current waveforms of lightning strokes to the CN Tower have been simultaneously measured since 1991. A new calculation model of electromagnetic field radiation is proposed. The proposed model consists of the lightning current propagation and distribution model and the electromagnetic field radiation model. Electromagnetic fields calculated by the proposed model, based on the observed lightning current at the CN Tower, agree well with the observed fields at 2km north of the tower.

  10. Extending membrane pore lifetime with AC fields: A modeling study

    NASA Astrophysics Data System (ADS)

    Garner, Allen L.; Bogdan Neculaes, V.

    2012-07-01

    AC (sinusoidal) fields with frequencies from kilohertz to gigahertz have been used for gene delivery. To understand the impact of AC fields on electroporation dynamics, we couple a nondimensionalized Smoluchowski equation to an exact representation of the cell membrane voltage obtained solving the Laplace equation. The slope of the pore energy function, dφ/dr, with respect to pore radius is critical in predicting pore dynamics in AC fields because it can vary from positive, inducing pore shrinkage, to negative, driving pore growth. Specifically, the net sign of the integral of dφ/dr over time determines whether the average pore size grows (negative), shrinks (positive), or oscillates (zero) indefinitely about a steady-state radius, rss. A simple analytic relationship predicting the amplitude of the membrane voltage necessary for this behavior agrees well with simulation for frequencies from 500 kHz to 5 MHz for rss < 10 nm. For larger pore size (rss > 10 nm), dφ/dr oscillates about a negative value, suggesting that a net creation of pores may be necessary to maintain a constant pore size. In both scenarios, the magnitude of rss depends only upon the amplitude of the membrane voltage and not directly upon the applied field frequency other than the relationship between the amplitudes of the applied field and membrane voltage.

  11. Polarization of radiation of electrons in highly turbulent magnetic fields

    NASA Astrophysics Data System (ADS)

    Prosekin, A. Yu.; Kelner, S. R.; Aharonian, F. A.

    2016-09-01

    We study the polarization properties of the jitter and synchrotron radiation produced by electrons in highly turbulent anisotropic magnetic fields. The net polarization is provided by the geometry of the magnetic field the directions of which are parallel to a certain plane. Such conditions may appear in the relativistic shocks during the amplification of the magnetic field through the so-called Weibel instability. While the polarization properties of the jitter radiation allows extraction of direct information on the turbulence spectrum as well as the geometry of magnetic field, the polarization of the synchrotron radiation reflects the distribution of the magnetic field over its strength. For the isotropic distribution of monoenergetic electrons, we found that the degree of polarization of the synchrotron radiation is larger than the polarization of the jitter radiation. For the power-law energy distribution of electrons the relation between the degree of polarization of synchrotron and jitter radiation depends on the spectral index of the distribution.

  12. Radiation burst from a single {gamma}-photon field

    SciTech Connect

    Shakhmuratov, R. N.; Vagizov, F.; Kocharovskaya, O.

    2011-10-15

    The radiation burst from a single {gamma}-photon field interacting with a dense resonant absorber is studied theoretically and experimentally. This effect was discovered for the fist time by P. Helisto et al.[Phys. Rev. Lett. 66, 2037 (1991)] and it was named the ''gamma echo''. The echo is generated by a 180 Degree-Sign phase shift of the incident radiation field, attained by an abrupt change of the position of the absorber with respect to the radiation source during the coherence time of the photon wave packet. Three distinguishing cases of the gamma echo are considered; i.e., the photon is in exact resonance with the absorber, close to resonance (on the slope of the absorption line), and far from resonance (on the far wings of the resonance line). In resonance the amplitude of the radiation burst is two times larger than the amplitude of the input radiation field just before its phase shift. This burst was explained by Helisto et al. as a result of constructive interference of the coherently scattered field with the phase-shifted input field, both having almost the same amplitude. We found that out of resonance the scattered radiation field acquires an additional component with almost the same amplitude as the amplitude of the incident radiation field. The phase of the additional field depends on the optical thickness of the absorber and resonant detuning. Far from resonance this field interferes destructively with the phase-shifted incident radiation field and radiation quenching is observed. Close to resonance the three fields interfere constructively and the amplitude of the radiation burst is three times larger than the amplitude of the input radiation field.

  13. Gravitational radiative corrections from effective field theory

    SciTech Connect

    Goldberger, Walter D.; Ross, Andreas

    2010-06-15

    In this paper we construct an effective field theory (EFT) that describes long wavelength gravitational radiation from compact systems. To leading order, this EFT consists of the multipole expansion, which we describe in terms of a diffeomorphism invariant point particle Lagrangian. The EFT also systematically captures 'post-Minkowskian' corrections to the multipole expansion due to nonlinear terms in general relativity. Specifically, we compute long distance corrections from the coupling of the (mass) monopole moment to the quadrupole moment, including up to two mass insertions. Along the way, we encounter both logarithmic short distance (UV) and long wavelength (IR) divergences. We show that the UV divergences can be (1) absorbed into a renormalization of the multipole moments and (2) resummed via the renormalization group. The IR singularities are shown to cancel from properly defined physical observables. As a concrete example of the formalism, we use this EFT to reproduce a number of post-Newtonian corrections to the gravitational wave energy flux from nonrelativistic binaries, including long distance effects up to 3 post-Newtonian (v{sup 6}) order. Our results verify that the factorization of scales proposed in the NRGR framework of Goldberger and Rothstein is consistent up to order 3PN.

  14. Extended virtual detector theory for strong-field atomic ionization.

    PubMed

    Wang, Xu; Tian, Justin; Eberly, J H

    2013-06-14

    For time-dependent strong-field atomic ionization a new theoretical approach is described that combines the numerical time-dependent Schrödinger equation (TDSE) and the numerical time-dependent Newtonian equation (TDNE). This approach keeps both the accuracy of quantum calculations and the speed of classical calculations. It does not use approximate tunneling formulas. It is applied to a recent experimental result, and we show its successful comparison to extensive TDSE calculations made under exactly the same conditions.

  15. Extended depth of field system for long distance iris acquisition

    NASA Astrophysics Data System (ADS)

    Chen, Yuan-Lin; Hsieh, Sheng-Hsun; Hung, Kuo-En; Yang, Shi-Wen; Li, Yung-Hui; Tien, Chung-Hao

    2012-10-01

    Using biometric signatures for identity recognition has been practiced for centuries. Recently, iris recognition system attracts much attention due to its high accuracy and high stability. The texture feature of iris provides a signature that is unique for each subject. Currently most commercial iris recognition systems acquire images in less than 50 cm, which is a serious constraint that needs to be broken if we want to use it for airport access or entrance that requires high turn-over rate . In order to capture the iris patterns from a distance, in this study, we developed a telephoto imaging system with image processing techniques. By using the cubic phase mask positioned front of the camera, the point spread function was kept constant over a wide range of defocus. With adequate decoding filter, the blurred image was restored, where the working distance between the subject and the camera can be achieved over 3m associated with 500mm focal length and aperture F/6.3. The simulation and experimental results validated the proposed scheme, where the depth of focus of iris camera was triply extended over the traditional optics, while keeping sufficient recognition accuracy.

  16. Adiabatic compression and radiative compression of magnetic fields

    SciTech Connect

    Woods, C.H.

    1980-02-12

    Flux is conserved during mechanical compression of magnetic fields for both nonrelativistic and relativistic compressors. However, the relativistic compressor generates radiation, which can carry up to twice the energy content of the magnetic field compressed adiabatically. The radiation may be either confined or allowed to escape.

  17. Extended magnetohydrodynamic simulations of field reversed configuration formation and sustainment with rotating magnetic field current drive

    NASA Astrophysics Data System (ADS)

    Milroy, R. D.; Kim, C. C.; Sovinec, C. R.

    2010-06-01

    Three-dimensional simulations of field reversed configuration (FRC) formation and sustainment with rotating magnetic field (RMF) current drive have been performed with the NIMROD code [C. R. Sovinec et al., J. Comput. Phys. 195, 355 (2004)]. The Hall term is a zeroth order effect with strong coupling between Fourier components, and recent enhancements to the NIMROD preconditioner allow much larger time steps than was previously possible. Boundary conditions to capture the effects of a finite length RMF antenna have been added, and simulations of FRC formation from a uniform background plasma have been performed with parameters relevant to the translation, confinement, and sustainment-upgrade experiment at the University of Washington [H. Y. Guo, A. L. Hoffman, and R. D. Milroy, Phys. Plasmas 14, 112502 (2007)]. The effects of both even-parity and odd-parity antennas have been investigated, and there is no evidence of a disruptive instability for either antenna type. It has been found that RMF effects extend considerably beyond the ends of the antenna, and that a large n =0 Bθ can develop in the open-field line region, producing a back torque opposing the RMF.

  18. Self-consistent undulator radiation via Lienard-Wiechert fields

    NASA Astrophysics Data System (ADS)

    Elias, Luis R.; Tecimer, Musit; Kimel, Isidoro

    1995-09-01

    Using Lienard-Wiechert fields and the Lorentz Force relation we present self consistent 3D radiation studies of electron beams moving through periodic electromagnetic structures such as those present in synchrotrons and free-electron laser undulators. Besides providing an economical means of calculating 3D vector radiation fields, our approach yields new insights into individual electron motion as it is driven by both, the velocity fields (Coulomb Fields) and the radiation fields generated by other electrons. We present results of electron beam compression resulting from longitudinal radiation forces competing in opposition with repulsive velocity field forces. We discuss results of noiseless 3D Self Amplified Spontaneous Emission in the X-Ray region resulting from the interaction of a filamentary electron beam with a circularly polarized magnetic undulator.

  19. Radiation field associated with Hiroshima and Nagasaki

    SciTech Connect

    Loewe, W.E.

    1984-08-01

    Accuracy of dosimetric estimates can determine the value of the atomic bomb survivor experience in establishing radiation risks. The status of a major revision of this dosimetry, initiated in 1980, is assessed. 3 references, 6 figures.

  20. Radiation reaction in quantum field theory

    NASA Astrophysics Data System (ADS)

    Higuchi, Atsushi

    2002-11-01

    We investigate radiation-reaction effects for a charged scalar particle accelerated by an external potential realized as a space-dependent mass term in quantum electrodynamics. In particular, we calculate the position shift of the final-state wave packet of the charged particle due to radiation at lowest order in the fine structure constant α and in the small ħ approximation. We show that it disagrees with the result obtained using the Lorentz-Dirac formula for the radiation-reaction force, and that it agrees with the classical theory if one assumes that the particle loses its energy to radiation at each moment of time according to the Larmor formula in the static frame of the potential. However, the discrepancy is much smaller than the Compton wavelength of the particle. We also point out that the electromagnetic correction to the potential has no classical limit.

  1. Activation of extended red emission photoluminescence in carbon solids by exposure to atomic hydrogen and UV radiation

    NASA Technical Reports Server (NTRS)

    Furton, Douglas G.; Witt, Adolf N.

    1993-01-01

    We report on new laboratory results which relate directly to the observation of strongly enhanced extended red emission (ERE) by interstellar dust in H2 photodissociation zones. The ERE has been attributed to photoluminescence by hydrogenated amorphous carbon (HAC). We are demonstrating that exposure to thermally dissociated atomic hydrogen will restore the photoluminescence efficiency of previously annealed HAC. Also, pure amorphous carbon (AC), not previously photoluminescent, can be induced to photoluminesce by exposure to atomic hydrogen. This conversion of AC into HAC is greatly enhanced by the presence of UV irradiation. The presence of dense, warm atomic hydrogen and a strong UV radiation field are characteristic environmental properties of H2 dissociation zones. Our results lend strong support to the HAC photoluminescence explanation for ERE.

  2. Detection of alpha radiation in a beta radiation field

    DOEpatents

    Mohagheghi, Amir H.; Reese, Robert P.

    2001-01-01

    An apparatus and method for detecting alpha particles in the presence of high activities of beta particles utilizing an alpha spectrometer. The apparatus of the present invention utilizes a magnetic field applied around the sample in an alpha spectrometer to deflect the beta particles from the sample prior to reaching the detector, thus permitting detection of low concentrations of alpha particles. In the method of the invention, the strength of magnetic field required to adequately deflect the beta particles and permit alpha particle detection is given by an algorithm that controls the field strength as a function of sample beta energy and the distance of the sample to the detector.

  3. Passive Millimeter-Wave Imaging with Extended Depth of Field and Sparse Data

    DTIC Science & Technology

    2012-05-01

    ing, extended depth-of-field, image reconstruction, sparsity. 1. INTRODUCTION Over the past several years, imaging using millimeter wave ( mmW ) and...two people with various weapons concealed under clothing. Note that concealed weapons are clearly detected in the mmW image. Recently, in [3], Mait et...al. presented a computational imaging method to extend the depth-of-field of a passive mmW imaging sys- tem. The method uses a cubic phase element in

  4. An extended field method solution for a pulse loaded thin plate

    NASA Technical Reports Server (NTRS)

    Donaldson, B. K.; Starkey, N. B.

    1980-01-01

    This paper deals with a new extension of a weighted residual method of analysis called the extended field method. The extended field method is applied for the first time to the problem of the transient vibration of a uniformly thin elastic plate. Numerical results have been obtained which validate the analysis procedure and show better solution convergence than is obtainable by standard methods of analysis for the same number of degrees of freedom. Further studies are necessary to obtain still better convergence.

  5. Revisiting thermal radiation in the near field

    NASA Astrophysics Data System (ADS)

    Greffet, Jean-Jacques

    2017-01-01

    Thermal radiation is generally assumed to be both spatially and temporally incoherent. In this paper, we challenge this idea. It is possible to design incandescent sources that are directional and spectrally selective by taking advantage of surface waves. We also report the discovery of the enhancement by several orders of magnitude of the energy density close to an interface at a particular frequency as well as the enhancement of the radiative flux between two interfaces when surface phonon polaritons can be excited. These results lead to the design of a novel class of infrared incandescent sources with potential applications in spectroscopy and thermophotovoltaic energy conversion. xml:lang="fr"

  6. Near-field radiative thermal transport: From theory to experiment

    SciTech Connect

    Song, Bai Fiorino, Anthony; Meyhofer, Edgar; Reddy, Pramod

    2015-05-15

    Radiative thermal transport via the fluctuating electromagnetic near-field has recently attracted increasing attention due to its fundamental importance and its impact on a range of applications from data storage to thermal management and energy conversion. After a brief historical account of radiative thermal transport, we summarize the basics of fluctuational electrodynamics, a theoretical framework for the study of radiative heat transfer in terms of thermally excited propagating and evanescent electromagnetic waves. Various approaches to modeling near-field thermal transport are briefly discussed, together with key results and proposals for manipulation and utilization of radiative heat flow. Subsequently, we review the experimental advances in the characterization of both near-field heat flow and energy density. We conclude with remarks on the opportunities and challenges for future explorations of radiative heat transfer at the nanoscale.

  7. Improving the radiation hardness of graphene field effect transistors

    NASA Astrophysics Data System (ADS)

    Alexandrou, Konstantinos; Masurkar, Amrita; Edrees, Hassan; Wishart, James F.; Hao, Yufeng; Petrone, Nicholas; Hone, James; Kymissis, Ioannis

    2016-10-01

    Ionizing radiation poses a significant challenge to the operation and reliability of conventional silicon-based devices. Here, we report the effects of gamma radiation on graphene field-effect transistors (GFETs), along with a method to mitigate those effects by developing a radiation-hardened version of our back-gated GFETs. We demonstrate that activated atmospheric oxygen from the gamma ray interaction with air damages the semiconductor device, and damage to the substrate contributes additional threshold voltage instability. Our radiation-hardened devices, which have protection against these two effects, exhibit minimal performance degradation, improved stability, and significantly reduced hysteresis after prolonged gamma radiation exposure. We believe this work provides an insight into graphene's interactions with ionizing radiation that could enable future graphene-based electronic devices to be used for space, military, and other radiation-sensitive applications.

  8. Improving the radiation hardness of graphene field effect transistors

    DOE PAGES

    Alexandrou, Konstantinos; Masurkar, Amrita; Edrees, Hassan; ...

    2016-10-11

    Ionizing radiation poses a significant challenge to the operation and reliability of conventional silicon-based devices. In this paper, we report the effects of gamma radiation on graphene field-effect transistors (GFETs), along with a method to mitigate those effects by developing a radiation-hardened version of our back-gated GFETs. We demonstrate that activated atmospheric oxygen from the gamma ray interaction with air damages the semiconductor device, and damage to the substrate contributes additional threshold voltage instability. Our radiation-hardened devices, which have protection against these two effects, exhibit minimal performance degradation, improved stability, and significantly reduced hysteresis after prolonged gamma radiation exposure. Finally,more » we believe this work provides an insight into graphene's interactions with ionizing radiation that could enable future graphene-based electronic devices to be used for space, military, and other radiation-sensitive applications.« less

  9. Improving the radiation hardness of graphene field effect transistors

    SciTech Connect

    Alexandrou, Konstantinos; Masurkar, Amrita; Edrees, Hassan; Wishart, James F.; Hao, Yufeng; Petrone, Nicholas; Hone, James; Kymissis, Ioannis

    2016-10-11

    Ionizing radiation poses a significant challenge to the operation and reliability of conventional silicon-based devices. In this paper, we report the effects of gamma radiation on graphene field-effect transistors (GFETs), along with a method to mitigate those effects by developing a radiation-hardened version of our back-gated GFETs. We demonstrate that activated atmospheric oxygen from the gamma ray interaction with air damages the semiconductor device, and damage to the substrate contributes additional threshold voltage instability. Our radiation-hardened devices, which have protection against these two effects, exhibit minimal performance degradation, improved stability, and significantly reduced hysteresis after prolonged gamma radiation exposure. Finally, we believe this work provides an insight into graphene's interactions with ionizing radiation that could enable future graphene-based electronic devices to be used for space, military, and other radiation-sensitive applications.

  10. The Electromagnetic Dipole Radiation Field through the Hamiltonian Approach

    ERIC Educational Resources Information Center

    Likar, A.; Razpet, N.

    2009-01-01

    The dipole radiation from an oscillating charge is treated using the Hamiltonian approach to electrodynamics where the concept of cavity modes plays a central role. We show that the calculation of the radiation field can be obtained in a closed form within this approach by emphasizing the role of coherence between the cavity modes, which is…

  11. Radiation tolerant silicon nitride insulated gate field effect transistors

    NASA Technical Reports Server (NTRS)

    Newman, P. A.

    1969-01-01

    Metal-Insulated-Semiconductor Field Effect Transistor /MISFET/ device uses a silicon nitride passivation layer over a thin silicon oxide layer to enhance the radiation tolerance. It is useful in electronic systems exposed to space radiation environment or the effects of nuclear weapons.

  12. About the National Center for Radiation Field Operations (NCRFO)

    EPA Pesticide Factsheets

    The National Center for Radiation Field Operations (NCRFO) is an essential component of EPA’s Radiological Emergency Response Team (RERT) and is key to EPA's response to radiological emergencies and accidents nationwide.

  13. School Facilities and Electric and Magnetic Field Radiation.

    ERIC Educational Resources Information Center

    Carr, Richard L.

    1990-01-01

    The possibility that electric and magnetic field radiation poses a health hazard should be recognized during the planning and designing of a school. A preconstruction assessment of possible exposure should be evaluated before the start of construction. (MLF)

  14. Hydrogen Absorbing Materials for Use as Radiation Shielding During Extended Space Flight Missions

    NASA Technical Reports Server (NTRS)

    Grugel, Richard N.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Minimizing radiation exposure from the galactic cosmic ray (GCR) environment during extended space missions is particularly crucial to crew health and safety. Here, an ideal candidate for shielding would be pure solid or liquid hydrogen, a material that effectively fragments heavy ions into ones of lower mass and energy that are more easily attenuated. Unfortunately, utilizing pure hydrogen is not presently feasible. It is, however, known that the hydrogen content of other materials (for example, metal hydrides, palladium alloys, and organic compounds) can exceed that of pure solid hydrogen and thus merit consideration as shielding candidates. This presentation will discuss an ongoing effort to develop novel shielding from such materials in concert with a coordinated testing/evaluation and modeling effort.

  15. Extended Kalman filter for attitude estimation of the earth radiation budget satellite

    NASA Technical Reports Server (NTRS)

    Deutschmann, Julie; Bar-Itzhack, Itzhack Y.

    1989-01-01

    The design and testing of an Extended Kalman Filter (EKF) for ground attitude determination, misalignment estimation and sensor calibration of the Earth Radiation Budget Satellite (ERBS) are described. Attitude is represented by the quaternion of rotation and the attitude estimation error is defined as an additive error. Quaternion normalization is used for increasing the convergence rate and for minimizing the need for filter tuning. The development of the filter dynamic model, the gyro error model and the measurement models of the Sun sensors, the IR horizon scanner and the magnetometers which are used to generate vector measurements are also presented. The filter is applied to real data transmitted by ERBS sensors. Results are presented and analyzed and the EKF advantages as well as sensitivities are discussed. On the whole the filter meets the expected synergism, accuracy and robustness.

  16. Thermal Diodes Based on Near-Field Radiation

    DTIC Science & Technology

    2015-10-01

    AFRL-RY-WP-TR-2015-0163 THERMAL DIODES BASED ON NEAR-FIELD RADIATION Michal Lipson Cornell University OCTOBER 2015...BASED ON NEAR-FIELD RADIATION 5a. CONTRACT NUMBER FA8650-14-1-7406 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 61101E 6. AUTHOR(S) Michal...45433-7320 Air Force Materiel Command United States Air Force Defense Advanced Research Projects Agency 675 North Randolph Street Arlington, VA

  17. A systematic study of finite field-dependent BRST-BV transformations in Sp(2) extended field-antifield formalism

    NASA Astrophysics Data System (ADS)

    Batalin, Igor A.; Bering, Klaus; Lavrov, Peter M.; Tyutin, Igor V.

    2014-11-01

    In the framework of Sp(2) extended Lagrangian field-antifield BV formalism, we study systematically the role of finite field-dependent BRST-BV transformations. We have proved that the Jacobian of a finite BRST-BV transformation is capable of generating arbitrary finite change of the gauge-fixing function in the path integral.

  18. Involved field radiation for Hodgkin's lymphoma: The actual dose to breasts in close proximity

    SciTech Connect

    Dabaja, Bouthaina; Wang Zhonglo; Stovall, Marilyn; Baker, Jamie S.; Smith, Susan A.; Khan, Meena; Ballas, Leslie; Salehpour, Mohammad R.

    2012-01-01

    To decrease the risk of late toxicities in Hodgkin's lymphoma (HL) patients treated with radiation therapy (RT) (HL), involved field radiation therapy (IFRT) has largely replaced the extended fields. To determine the out-of-field dose delivered from a typical IFRT to surrounding critical structures, we measured the dose at various points in an anthropomorphic phantom. The phantom is divided into 1-inch-thick slices with the ability to insert TLDs at 3-cm intervals grid spacing. Two treatment fields were designed, and a total of 45 TLDs were placed (equally spaced) at the margin of the each of the 2 radiation fields. After performing a computed tomography simulation, 2 treatment plans targeting the mediastinum, a typical treatment field in patients with early stage HL, were generated. A total dose of 3060 cGy was delivered to the gross tumor volume for each field consecutively. The highest measured dose detected at 1 cm from the field edge in the planning target volume was 496 cGy, equivalent to 16% of the isocentric dose. The dose dropped significantly with increasing distance from the field edge. It ranged from 1.1-3.9% of the isocentric dose at a distance of 3.2-4 cm to <1.6% at a distance of >6 cm. Although the computer treatment planning system (CTPS) frequently underestimated the dose delivered, the difference in dose between measured and generated by CTPS was <2.5% in 90 positions measured. The collateral dose of radiation to breasts from IFRT is minimal. The out-of-field dose, although mildly underestimated by CTPS, becomes insignificant at >3 cm from the field edge of the radiation field.

  19. Radiative corrections to the Zbb vertex and constraints on extended Higgs sectors

    NASA Astrophysics Data System (ADS)

    Logan, Heather Erin

    1999-10-01

    We explore the radiative corrections to the process Z-->bb in models with extended Higgs sectors. The observables R b and Ab are sensitive to these corrections. Rb is the hadronic branching fraction of Z bosons to bb,Rb =G(Z-->hadrons) . Ab is the b quark asymmetry, Ab=(g2L- g2 R)/(g2 L+g2R) where gL and gR are the left and right handed couplings of Z to b quarks. We find that in models containing only doublets, singlets, or larger multiplets constrained by a custodial SU(2) c symmetry so that MW=MZcosqW at tree level, the corrections involving charged Higgs bosons always worsen agreement with experiment. The Rb measurement can be used to set lower bounds on the charged Higgs masses in such models. Corrections involving light neutral Higgs bosons in models with enhanced H0bb coupling (large tan β) can improve agreement with experiment over the Standard Model. We present general formulas for the corrections to Rb and Ab in an arbitrary extended Higgs sector, and derive explicit results for a number of specific models.

  20. Radiation from Relativistic Shocks with Turbulent Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Nishkawa, K.; Medvedev, M.; Zhang, B.; Hardee, P.; Niemiec, J.; Mizuno, A.; Nordlund, A.; Frederiksen, J.; Sol, H.; Pohl, M.; Hartmann, D. H.; Oka, M.; Fishman, J.

    2009-01-01

    Recent PIC simulations of relativistic electron-positron (electron-ion) jets injected into a stationary medium show that particle acceleration occurs at shocked region. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the shock. The "jitter" radiation from deflected electrons in turbulent magnetic fields has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. New recent calculation of spectra with various different Lorentz factors of jets (two electrons) and initial magnetic fields. New spectra based on small simulations will be presented.

  1. The Geomagnetic Field and Radiation in Near-Earth Orbits

    NASA Technical Reports Server (NTRS)

    Heirtzler, J. R.

    1999-01-01

    This report shows, in detail, how the geomagnetic field interacts with the particle flux of the radiation belts to create a hazard to spacecraft and humans in near-Earth orbit. It illustrates the geometry of the geomagnetic field lines, especially around the area where the field strength is anomalously low in the South Atlantic Ocean. It discusses how the field will probably change in the future and the consequences that may have on hazards in near space.

  2. Normal mode sound field of a directional radiator

    NASA Astrophysics Data System (ADS)

    Zhang, R.; Zhu, B.

    1987-12-01

    In this paper, the sound field of a general type of directional radiator in a stratified medium is treated, and the concept of directivity is applied to calculation of the normal modes. The result shows that the normal mode field of a directional radiator can be obtained by supplementing the normal mode expression of an omnidirectional point source with the directional excitation function, which is dependent on the position and directivity of the radiator. In addition, the normal mode fields of radiators with vertical-symmetrical, vertical-antisymmetrical, single-sided and sharp directivities are calculated, respectively. For a vertical line array in a homogeneous water layer, if the source distribution is proportional to the eigenfunction of some normal mode, the zeros of the directional excitation function correspond precisely to the directions of the eigenrays of other normal modes.

  3. Electron trajectories in pulsed radiation fields

    SciTech Connect

    Einwohner, T.; Lippmann, B.A.

    1987-05-01

    The work reported here analyzes the dynamical behavior of an electron, initially at rest, when subjected to a radiation pulse of arbitrary, but integrable, shape. This is done by a general integration procedure that has been programmed in VAXIMA. Upon choosing a specific shape for the pulse, VAXIMA finds both the space-time trajectory and the four-momentum of the electron. These are obtained in analytic or numerical form - or both - at the choice of the user. Several examples of analytical and numerical solutions, for different pulse shapes, are given.

  4. Wayward Field Lines Challenge Solar Radiation Models

    NASA Video Gallery

    This video compares the two models for particle distribution over the course of just three hours after an SEP event. The white line represents a magnetic field line, the general path that the SEPs ...

  5. Fission Product Transmutation in Mixed Radiation Fields

    SciTech Connect

    Harmon, Frank; Burgett, Erick; Starovoitova, Valeriia; Tsveretkov, Pavel

    2015-01-15

    Work under this grant addressed a part of the challenge facing the closure of the nuclear fuel cycle; reducing the radiotoxicity of lived fission products (LLFP). It was based on the possibility that partitioning of isotopes and accelerator-based transmutation on particular LLFP combined with geological disposal may lead to an acceptable societal solution to the problem of management. The feasibility of using photonuclear processes based on the excitation of the giant dipole resonance (GDR) by bremsstrahlung radiation as a cost effective transmutation method was accessed. The nuclear reactions of interest: (γ,xn), (n,γ), (γ,p) can be induced by bremsstrahlung radiation produced by high power electron accelerators. The driver of these processes would be an accelerator that produces a high energy and high power electron beam of ~ 100 MeV. The major advantages of such accelerators for this purpose are that they are essentially available “off the shelf” and potentially would be of reasonable cost for this application. Methods were examined that used photo produced neutrons or the bremsstrahlung photons only, or use both photons and neutrons in combination for irradiations of selected LLFP. Extrapolating the results to plausible engineering scale transmuters it was found that the energy cost for 129I and 99Tc transmutation by these methods are about 2 and 4%, respectively, of the energy produced from 1000MWe.

  6. Adaptive radiations: From field to genomic studies

    PubMed Central

    Hodges, Scott A.; Derieg, Nathan J.

    2009-01-01

    Adaptive radiations were central to Darwin's formation of his theory of natural selection, and today they are still the centerpiece for many studies of adaptation and speciation. Here, we review the advantages of adaptive radiations, especially recent ones, for detecting evolutionary trends and the genetic dissection of adaptive traits. We focus on Aquilegia as a primary example of these advantages and highlight progress in understanding the genetic basis of flower color. Phylogenetic analysis of Aquilegia indicates that flower color transitions proceed by changes in the types of anthocyanin pigments produced or their complete loss. Biochemical, crossing, and gene expression studies have provided a wealth of information about the genetic basis of these transitions in Aquilegia. To obtain both enzymatic and regulatory candidate genes for the entire flavonoid pathway, which produces anthocyanins, we used a combination of sequence searches of the Aquilegia Gene Index, phylogenetic analyses, and the isolation of novel sequences by using degenerate PCR and RACE. In total we identified 34 genes that are likely involved in the flavonoid pathway. A number of these genes appear to be single copy in Aquilegia and thus variation in their expression may have been key for floral color evolution. Future studies will be able to use these sequences along with next-generation sequencing technologies to follow expression and sequence variation at the population level. The genetic dissection of other adaptive traits in Aquilegia should also be possible soon as genomic resources such as whole-genome sequencing become available. PMID:19528644

  7. Theoretical Studies Relating to the Interaction of Radiation with Matter: Atomic Collision Processes Occurring in the Presence of Radiation Fields.

    DTIC Science & Technology

    1980-10-01

    Zener problem (two-level atom subjected to a hyperbolic secant radiation pulse) has been extended to three level systems in which the field couples...well resemble true pulses. It also enables one to solve the two-level part of 2246 E J Robinson the problem analytically (Rosen and Zener 1932, Robiscoe...4Z(1 -Z)]N-2a 2(Z)12 dZ (8) with a 2 given in terms of the variable Z by (Robiscoe 1978, Rosen and Zener 1932) r(--c) 2F (c-a +1,c-b +1,2-c,Z) (9

  8. Spherical-wave expansions of piston-radiator fields.

    PubMed

    Wittmann, R C; Yaghjian, A D

    1991-09-01

    Simple spherical-wave expansions of the continuous-wave fields of a circular piston radiator in a rigid baffle are derived. These expansions are valid throughout the illuminated half-space and are useful for efficient numerical computation in the near-field region. Multipole coefficients are given by closed-form expressions which can be evaluated recursively.

  9. Supersymmetric extended string field theory in NSn sector and NSn - 1-R sector

    NASA Astrophysics Data System (ADS)

    Asano, Masako; Kato, Mitsuhiro

    2016-09-01

    We construct a class of quadratic gauge invariant actions for extended string fields defined on the tensor product of open superstring state space for multiple open string Neveu-Schwarz (NS) sectors with or without one Ramond (R) sector. The basic idea is the same as for the bosonic extended string field theory developed by the authors [1]. The theory for NSn sector and NS n - 1-R sector contains general n-th rank tensor fields and (n - 1)-th rank spinor-tensor fields in the massless spectrum respectively. In principle, consistent gauge invariant actions for any generic type of 10-dimensional massive or massless tensor or spinor-tensor fields can be extracted from the theory. We discuss some simple examples of bosonic and fermionic massless actions.

  10. Tomographic systems for the Helmholtz equation with extended Born field models using conjugate gradient inversion methods

    NASA Astrophysics Data System (ADS)

    Olsen, Scott Charles

    In this dissertation, new inverse scattering algorithms are derived for the Helmholtz equation using the Extended Born field model (eikonal rescattered field), and the angular spectrum (parabolic) layered field model. These two field models performed the 'best' of all the field models evaluated. Algorithms are solved with conjugate gradient methods. An advanced ultrasonic data acquisition system is also designed. Many different field models for use in a reconstruction algorithm are investigated. 'Layered' field models that mathematically partition the field calculation in layers in space possess the advantage that the field in layer n is calculated from the field in layer n - 1. Several of the 'layered' field models are investigated in terms of accuracy and computational complexity. Field model accuracy using field rescattering is also tested. The models investigated are the eikonal field model, the angular spectrum (AS) field model, and the parabolic field models known as the Split-Step Fast-Fourier Transform and the Crank-Nicolson algorithms. All of the 'layered' field models can be referred to as Extended Born field models since the 'layered' field models are more accurate than the Born approximated total field. The Rescattered Extended Born (eikonal rescattered field) Transmission Mode (REBTM) algorithm with the AS field model and the Nonrescattered AS Reconstruction (NASR) algorithm are tested with several types of objects: a single-layer cylinder, double-layer cylinders, two double-layer cylinders and the breast model. Both algorithms, REBTM and NASR work well; however, the NASR algorithm is faster and more accurate than the REBTM algorithm. The NASR algorithm is matched well with the requirements of breast model reconstructions. A major purpose of new scanner development is to collect both transmission and reflection data from multiple ultrasonic transducer arrays to test the next generation of reconstruction algorithms. The data acquisition system advanced

  11. Spontaneous Radiation Emission from Short, High Field Strength Insertion Devices

    SciTech Connect

    Geoffrey Krafft

    2005-09-15

    Since the earliest papers on undulaters were published, it has been known how to calculate the spontaneous emission spectrum from ''short'' undulaters when the magnetic field strength parameter is small compared to unity, or in ''single'' frequency sinusoidal undulaters where the magnetic field strength parameter is comparable to or larger than unity, but where the magnetic field amplitude is constant throughout the undulater. Fewer general results have been obtained in the case where the insertion device is both short, i.e., the magnetic field strength parameter changes appreciably throughout the insertion device, and the magnetic field strength is high enough that ponderomotive effects, radiation retardation, and harmonic generation are important physical phenomena. In this paper a general method is presented for calculating the radiation spectrum for short, high-field insertion devices. It is used to calculate the emission from some insertion device designs of recent interest.

  12. Variations of melatonin and stress hormones under extended shifts and radiofrequency electromagnetic radiation.

    PubMed

    Vangelova, Katia Koicheva; Israel, Mishel Salvador

    2005-01-01

    We studied the time-of-day variations in urinary levels of 6-sulphatoxy-melatonin and three stress hormones in operators working fast-rotating extended shifts under radiofrequency electromagnetic radiation (EMR). The excretion rate of the hormones was monitored by radioimmunoassay and spectrofluorimetry at 4-hour intervals in a group of 36 male operators comprising 12 broadcasting station operators, 12 TV station operators, and a control group of 12 satellite station operators. Measuring the time-weighted average (TWA) of EMR exposure revealed a high-level of exposure in broadcasting station operators (TWAmean= 3.10 microW/ cm2, TWAmax = 137.00 microW/cm2), a low-level in TV station operators (TWAmean = 1.89 microW/cm2, TWAmax = 5.24 microW/cm2), and a very low level in satellite station operators. The differences among the groups remained the same after confounding factors were taken into account. Radiofrequency EMR had no effect on the typical diurnal pattern of 6-sulphatoxymelatonin. High-level radiofrequency EMR exposure significantly increased the excretion rates of cortisol (p < 0.001), adrenaline (p = 0.028), and noradrenaline (p < 0.000), whereas changes under low-level exposure did not reach significance. The 24-hour excretion of cortisol and noradrenaline correlated with TWAmean and TWAmax. In conclusion, the excretion of 6-sulphatoxymelatonin retained a typical diurnal pattern under fast-rotating extended shifts and radiofrequency EMR, but showed an exposure-effect relation with stress hormones.

  13. Field Testing of a Portable Radiation Detector and Mapping System

    SciTech Connect

    Hofstetter, K.J.; Hayes, D.W.; Eakle, R.F.

    1998-03-01

    Researchers at the Savannah River Site (SRS) have developed a man- portable radiation detector and mapping system (RADMAPS) which integrates the accumulation of radiation information with precise ground locations. RADMAPS provides field personnel with the ability to detect, locate, and characterize nuclear material at a site or facility by analyzing the gamma or neutron spectra and correlating them with position. the man-portable field unit records gamma or neutron count rate information and its location, along with date and time, using an embedded Global Positioning System (GPS). RADMAPS is an advancement in data fusion, integrating several off-the-shelf technologies with new computer software resulting in a system that is simple to deploy and provides information useful to field personnel in an easily understandable form. Decisions on subsequent actions can be made in the field to efficiently use available field resources. The technologies employed in this system include: recording GPS, radiation detection (typically scintillation detectors), pulse height analysis, analog-to-digital converters, removable solid-state (Flash or SRAM) memory cards, Geographic Information System (GIS) software and personal computers with CD-ROM supporting digital base maps. RADMAPS includes several field deployable data acquisition systems designed to simultaneously record radiation and geographic positions. This paper summarizes the capabilities of RADMAPS and some of the results of field tests performed with the system.

  14. The dielectric response to the magnetic field of electromagnetic radiation

    NASA Astrophysics Data System (ADS)

    Mukherjee, Shouvik; Mukhopadhyay, Sourabh; Datta, Prasanta Kumar

    2017-04-01

    Light–matter interaction in transparent dielectrics is revisited, including the magnetic force on bound charges in the Lorentz oscillator model. The parameter ranges of incident radiation and the medium on which the magnetic field of the electromagnetic radiation will have a significant effect are traced using Floquet theory. The analysis reveals that the threshold intensity for a significant response of the magnetic field of the radiation at the second harmonic of the incident radiation can be reduced to {10}12 {{W}}{{cm}}-2 for off resonant and even lower for resonant interaction. This phenomenon has already been observed indirectly in experiments [1, 2]. Induced magnetizing current due to the magnetic force is shown to originate from a modified dielectric response, which may be useful in future magneto-optic devices, solar energy harvesting, and studying the ultrafast dynamics in doped dielectrics.

  15. Kidney-Sparing Methods for Extended-Field Intensity-Modulated Radiotherapy (EF-IMRT) in Cervical Carcinoma Treatment

    PubMed Central

    Kunogi, Hiroaki; Yamaguchi, Nanae; Terao, Yasuhisa; Sasai, Keisuke

    2016-01-01

    Coplanar extended-field intensity-modulated radiation therapy (EF-IMRT) targeting the whole-pelvic and para-aortic lymph nodes in patients with advanced cervical cancer results in impaired creatinine clearance. An improvement in renal function cannot be expected unless low-dose (approximately 10 Gy) kidney exposure is reduced. The dosimetric method should be considered during EF-IMRT planning to further reduce low-dose exposure to the kidneys. To assess the usefulness of non-coplanar EF-IMRT with kidney-avoiding beams to spare the kidneys during cervical carcinoma treatment in dosimetric analysis between non-coplanar and coplanar EF-IMRT, we compared the doses of the target organ and organs at risk, including the kidney, in 10 consecutive patients. To estimate the influence of EFRT on renal dysfunction, creatinine clearance values after treatment were also examined in 18 consecutive patients. Of these 18 patients, 10 patients who were included in the dosimetric analysis underwent extended field radiation therapy (EFRT) with concurrent chemotherapy, and eight patients underwent whole-pelvis radiation therapy with concurrent chemotherapy to treat cervical carcinoma between April 2012 and March 2015 at our institution. In the dosimetric analysis, non-coplanar EF-IMRT was effective at reducing low-dose (approximately 10 Gy) exposure to the kidneys, thus maintaining target coverage and sparing other organs at risk, such as the small bowel, rectum, and bladder, compared with coplanar EF-IMRT. Renal function in all 10 patients who underwent EFRT, including coplanar EF-IMRT (with kidney irradiation), was low after treatment, and differed significantly from that of the eight patients who underwent WPRT (no kidney irradiation) 6 months after the first day of treatment (P = 0.005). In conclusion, non-coplanar EF-IMRT should be considered in patients with advanced cervical cancer, particularly in patients with a long life expectancy or with pre-existing renal dysfunction. PMID

  16. Synchrotron radiation in strongly coupled conformal field theories

    SciTech Connect

    Athanasiou, Christiana; Chesler, Paul M.; Liu, Hong; Rajagopal, Krishna; Nickel, Dominik

    2010-06-15

    Using gauge/gravity duality, we compute the energy density and angular distribution of the power radiated by a quark undergoing circular motion in strongly coupled N=4 supersymmetric Yang-Mills theory. We compare the strong coupling results to those at weak coupling, finding them to be very similar. In both regimes, the angular distribution of the radiated power is in fact similar to that of synchrotron radiation produced by an electron in circular motion in classical electrodynamics: the quark emits radiation in a narrow beam along its velocity vector with a characteristic opening angle {alpha}{approx}1/{gamma}. To an observer far away from the quark, the emitted radiation appears as a short periodic burst, just like the light from a lighthouse does to a ship at sea. Our strong coupling results are valid for any strongly coupled conformal field theory with a dual classical gravity description.

  17. IAEA programme in the field of radiation technology

    NASA Astrophysics Data System (ADS)

    Chmielewski, Andrzej G.; Haji-Saeid, Mohammad

    2005-07-01

    Radiation technologies applying gamma sources and electron accelerators for material modification are well-established processes. There are over 160 gamma industrial irradiators and 1300 electron industrial accelerators in operation worldwide. A new advancement in the field of radiation sources engineering is the development of high power direct e-/X conversion sources based on electron accelerators. Technologies to be developed beside environmental applications could be nanomaterials, structure engineered materials (sorbents, composites, ordered polymers, etc.) and natural polymers' processing. New products based on radiation-processed polysaccharides have already been commercialised in many countries of the East Asia and Pacific Region, especially in those being rich in natural polymers. Very important and promising applications concern environmental protection-radiation technology, being a clean and environment friendly process, helps to curb pollutants' emission as well. Industrial plants for flue gas treatment have been constructed in Poland and China. The pilot plant in Bulgaria using this technology has just started its operation. The Polish plant is equipped with accelerators of over 1 MW power, a breakthrough in radiation technology application. The industrial plant for wastewater treatment is under development in Korea and a pilot plant for sewage sludge irradiation has been in operation in India for many years. Due to recent developments, the Agency has restructured its programme and organized a Technical Meeting (TM) on "Emerging Applications of Radiation Technology for the 21st Century" at its Headquarters in Vienna, Austria, in April 2003, to review the present situation and possible developments of radiation technology to contribute to a sustainable development. This meeting provided the basic input to launch others in the most important fields of radiation technology applications: "Advances in Radiation Chemistry of Polymers" (Notre Dame, USA

  18. Pion Production from Proton Synchrotron Radiation in Strong Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Maruyama, Tomoyuki; Cheoun, Myung-Ki; Kajino, Toshitaka; Mathews, Grant J.

    We study pion production by proton synchrotron radiation in the presence of a strong magnetic field. In this study we find that the decay width satisfies a robust scaling relation. This scaling implies that one can infer the decay width in more realistic magnetic fields of 1015 G, where ni,f ˜ 1012-1013, from the results for ni,f ˜ 104-105. Then, we present the resultant pion intensity and angular distributions for realistic magnetic field strengths.

  19. Cosmological fluctuations of a random field and radiation fluid

    SciTech Connect

    Bastero-Gil, Mar; Berera, Arjun; Moss, Ian G.; Ramos, Rudnei O. E-mail: ab@ph.ed.ac.uk E-mail: rudnei@uerj.br

    2014-05-01

    A generalization of the random fluid hydrodynamic fluctuation theory due to Landau and Lifshitz is applied to describe cosmological fluctuations in systems with radiation and scalar fields. The viscous pressures, parametrized in terms of the bulk and shear viscosity coefficients, and the respective random fluctuations in the radiation fluid are combined with the stochastic and dissipative scalar evolution equation. This results in a complete set of equations describing the perturbations in both scalar and radiation fluids. These derived equations are then studied, as an example, in the context of warm inflation. Similar treatments can be done for other cosmological early universe scenarios involving thermal or statistical fluctuations.

  20. Criteria for Personal Dosimetry in Mixed Radiation Fields in Space,

    DTIC Science & Technology

    1974-09-16

    of neutrons has not been reported on any manned mussion. Only limited data on thermal neutrons recorded with activation f9 ils and on a small section...the center. The bottom graph shows the distribution for neutron recoil protons from thermal fission of U-235 as reported by Kronenberg and Murphy (3...an equilibrium spectrum is established. For neutrons of galactic radiation, the equilibrium spectrum is a wide continuum extending from thermal to

  1. Conformation change of enzyme molecules in laser radiation field

    NASA Astrophysics Data System (ADS)

    Leshenyuk, N. S.; Prigun, M. V.; Apanasevitsh, E. E.; Kruglik, G. S.

    2007-06-01

    As a result of an analysis of macromolecules properties in the coherent optical radiation field and with allowance for the experimentally obtained unique data on the interaction of lazer radiation with biomolecules (dependence of the interaction efficiency on the coherence length, presence of the effect in the spectra region far from the absorption band), a mechanism of wave interaction is developed. Using this mathematical model, the calculations of a change in the macromolecules oscillatory energy in the coherent radiation field are performed. It is shown that the increase of macromolecules oscillatory energy depends strongly on the coherence length of radiation. On exposure to noncoherent radiation, the biomolecules oscillatory energy practically does not change, whereas on exposure to laser radiation (coherence length ~3 cm), energy of oscillations of atoms increases by an order of 2÷4, which results in a change in the conformation of biomolecules and activity of enzymes. Recently a lot of data are received concerning the change of lysosomal enzymes activity in blood plasma under action of laser radiation.

  2. Comparison of locoregional versus extended locoregional radiation volumes for patients with non-metastatic gastro-esophageal junction carcinomas

    PubMed Central

    Wang, Jingya; Milton, Denái R.; He, Liru; Komaki, Ritsuko; Liao, Zhongxing; Crane, Christopher H.; Minsky, Bruce D.; Thall, Peter F.; Lin, Steven H.

    2015-01-01

    Introduction To delineate an optimal clinical target volume (CTV) for gastroesophageal junction (GEJ) cancers by comparing locoregional vs. extended locoregional radiation volumes. Materials This retrospective analysis examined 222 patients (111 matched pairs treated with locoregional vs. extended locoregional radiation) with non-metastatic GEJ carcinomas treated with concurrent chemoradiation +/- surgery. The CTV for locoregional volumes was defined as gross tumor volume (GTV) + elective coverage of first-echelon nodes and sometimes the celiac axis. The CTV for extended locoregional volumes was defined as GTV + elective coverage of celiac and splenic (+/- porta) nodes. Variables used for matching included gender, stage, performance status, histology, receipt of induction chemotherapy, type of concurrent chemotherapy, radiation modality, receipt of surgery, type of surgery, and Siewert classification. Regression models stratified by matched pairs were fit to estimate effect of radiation volume on clinical endpoints. Results Adjusting p-values for multiple testing, patients treated with extended locoregional vs. locoregional radiation had increased odds of grade 2+ acute chemoradiation-associated GI toxicity (OR 2.92, adj. p=0.0447). However, differing radiation volumes were not significantly associated with postoperative complication rates, pathologic T-stage, frequency of positive perigastric/regional nodes on surgical specimen, distant-metastases progression free survival, locoregional progression free survival, or overall survival (adj. p>0.05). Of the patients who did (N=124) and did not (N=72) receive elective celiac radiation, 2 (1.6%) and 2 (2.8%) patients, respectively, relapsed in the celiac nodes. No patients failed in the splenic or porta nodes. Conclusions Most GEJ cancers can be safely treated without elective inclusion of splenic/porta nodes. PMID:25695222

  3. Comparison and testing of extended Kalman filters for attitude estimation of the Earth radiation budget satellite

    NASA Technical Reports Server (NTRS)

    Deutschmann, Julie; Bar-Itzhack, Itzhack Y.; Rokni, Mohammad

    1990-01-01

    The testing and comparison of two Extended Kalman Filters (EKFs) developed for the Earth Radiation Budget Satellite (ERBS) is described. One EKF updates the attitude quaternion using a four component additive error quaternion. This technique is compared to that of a second EKF, which uses a multiplicative error quaternion. A brief development of the multiplicative algorithm is included. The mathematical development of the additive EKF was presented in the 1989 Flight Mechanics/Estimation Theory Symposium along with some preliminary testing results using real spacecraft data. A summary of the additive EKF algorithm is included. The convergence properties, singularity problems, and normalization techniques of the two filters are addressed. Both filters are also compared to those from the ERBS operational ground support software, which uses a batch differential correction algorithm to estimate attitude and gyro biases. Sensitivity studies are performed on the estimation of sensor calibration states. The potential application of the EKF for real time and non-real time ground attitude determination and sensor calibration for future missions such as the Gamma Ray Observatory (GRO) and the Small Explorer Mission (SMEX) is also presented.

  4. Radiation of Electron in the Field of Plane Light Wave

    SciTech Connect

    Zelinsky, A.; Drebot, I.V.; Grigorev, Yu.N.; Zvonareva, O.D.; Tatchyn, R.; /SLAC

    2006-02-24

    Results of integration of a Lorentz equation for a relativistic electron moving in the field of running, plane, linear polarized electromagnetic wave are presented in the paper. It is shown that electron velocities in the field of the wave are almost periodic functions of time. For calculations of angular spectrum of electron radiation intensity expansion of the electromagnetic field in a wave zone into generalized Fourier series was used. Expressions for the radiation intensity spectrum are presented in the paper. Derived results are illustrated for electron and laser beam parameters of NSC KIPT X-ray generator NESTOR. It is shown that for low intensity of the interacting electromagnetic wave the results of energy and angular spectrum calculations in the frame of classical electrodynamics completely coincide with calculation results produced using quantum electrodynamics. Simultaneously, derived expressions give possibilities to investigate dependence of energy and angular Compton radiation spectrum on phase of interaction and the interacting wave intensity.

  5. Postoperative extended-volume external-beam radiation therapy in high-risk esophageal cancer patients: a prospective experience

    PubMed Central

    Yu, E.; Tai, P.; Younus, J.; Malthaner, R.; Truong, P.; Stitt, L.; Rodrigues, G.; Ash, R.; Dar, R.; Yaremko, B.; Tomiak, A.; Dingle, B.; Sanatani, M.; Vincent, M.; Kocha, W.; Fortin, D.; Inculet, R.

    2009-01-01

    Background and Purpose Extended-volume external-beam radiation therapy (rt) following esophagectomy is controversial. The present prospective study evaluates the feasibility of extended-volume rt treatment in high-risk esophagectomy patients with a cervical anastomosis receiving postoperative combined chemoradiation therapy. Patients and Methods From 2001 to 2006, 15 patients with resected esophageal cancer were prospectively accrued to this pilot study to evaluate the adverse effects of extended-volume rt. Postoperative management was carried out at London Regional Cancer Program. Eligibility criteria were pathology-proven esophageal malignancy (T3–4, N0–1), disease amenable to surgical resection, and esophagectomy with or without resection margin involvement. Patients with distant metastases (M1) and patients treated with previous rt were excluded. All 15 study patients received 4 cycles of 5-fluorouracil–based chemotherapy. External-beam rt was conducted using conformal computed tomography planning, with multi-field arrangement tailored to the pathology findings, with coverage of a clinical target volume encompassing the primary tumour bed and the anastomotic site in the neck. The radiation therapy dose was 50.40 Gy at 1.8 Gy per fraction. The rt was delivered concurrently with the third cycle of chemotherapy. The study outcomes—disease-free survival (dfs) and overall survival (os)—were calculated by the Kaplan–Meier method. Treatment-related toxicities were assessed using the U.S. National Cancer Institute’s Common Toxicity Criteria. Results The study accrued 10 men and 5 women of median age 64 years (range: 48–80 years) and TNM stages T3N0 (n = 1), T2N1 (n = 2), T3N1 (n = 11), and T4N1 (n = 1). Histopathology included 5 adenocarcinomas and 10 squamous-cell carcinomas. Resection margins were clear in 10 patients. The median follow-up time was 19 months (range: 3.5–53.4 months). Before radiation therapy commenced, delay in chemotherapy occurred

  6. Extended depth-of-field microscopy with a high-speed deformable mirror.

    PubMed

    Shain, William J; Vickers, Nicholas A; Goldberg, Bennett B; Bifano, Thomas; Mertz, Jerome

    2017-03-01

    We present a wide-field fluorescence microscopy add-on that provides a fast, light-efficient extended depth-of-field (EDOF) using a deformable mirror with an update rate of 20 kHz. Out-of-focus contributions in the raw EDOF images are suppressed with a deconvolution algorithm derived directly from the microscope 3D optical transfer function. Demonstrations of the benefits of EDOF microscopy are shown with GCaMP-labeled mouse brain tissue.

  7. XTEND: Extending the depth of field in cryo soft X-ray tomography.

    PubMed

    Otón, Joaquín; Pereiro, Eva; Conesa, José J; Chichón, Francisco J; Luque, Daniel; Rodríguez, Javier M; Pérez-Berná, Ana J; Sorzano, Carlos Oscar S; Klukowska, Joanna; Herman, Gabor T; Vargas, Javier; Marabini, Roberto; Carrascosa, José L; Carazo, José M

    2017-04-04

    We have developed a new data collection method and processing framework in full field cryo soft X-ray tomography to computationally extend the depth of field (DOF) of a Fresnel zone plate lens. Structural features of 3D-reconstructed eukaryotic cells that are affected by DOF artifacts in standard reconstruction are now recovered. This approach, based on focal series projections, is easily applicable with closed expressions to select specific data acquisition parameters.

  8. XTEND: Extending the depth of field in cryo soft X-ray tomography

    PubMed Central

    Otón, Joaquín; Pereiro, Eva; Conesa, José J.; Chichón, Francisco J.; Luque, Daniel; Rodríguez, Javier M.; Pérez-Berná, Ana J.; Sorzano, Carlos Oscar S.; Klukowska, Joanna; Herman, Gabor T.; Vargas, Javier; Marabini, Roberto; Carrascosa, José L.; Carazo, José M.

    2017-01-01

    We have developed a new data collection method and processing framework in full field cryo soft X-ray tomography to computationally extend the depth of field (DOF) of a Fresnel zone plate lens. Structural features of 3D-reconstructed eukaryotic cells that are affected by DOF artifacts in standard reconstruction are now recovered. This approach, based on focal series projections, is easily applicable with closed expressions to select specific data acquisition parameters. PMID:28374769

  9. The response of survey meters to pulsed radiation fields

    SciTech Connect

    McCall, R.C.; Ipe, N.E.

    1987-11-01

    The response of most survey meters to steady radiation fields is fairly well known and documented. However, hardly any data is available in the literature regarding the response of these instruments to pulsed radiation. Pulsed radiation fields are encountered, e.g., in the vicinity of linear electron accelerators or klystrons. An instrument that ordinarily responds well to the average dose rate spread out evenly in time may not be able to cope with such a high dose rate. Instruments which have long dead times such as Geiger Mueller and proportional counters tend to become saturated in such fields and only count repetition rate. Ionization chambers are less influenced, however, they must be operated with adequate voltage to overcome recombination losses. Scintillation survey meters may become non-linear at higher dose rates for pulsed radiation because the photomultiplier cannot handle the instantaneous currents that are required. Because of the need to test the response of different radiation detection instruments to pulsed fields, a pulsed x-ray facility has been built (I/sub p/87). A brief description of this facility is given along with tests of several different instruments. 5 refs., 4 figs., 1 tab.

  10. Design of Optical Systems with Extended Depth of Field: An Educational Approach to Wavefront Coding Techniques

    ERIC Educational Resources Information Center

    Ferran, C.; Bosch, S.; Carnicer, A.

    2012-01-01

    A practical activity designed to introduce wavefront coding techniques as a method to extend the depth of field in optical systems is presented. The activity is suitable for advanced undergraduate students since it combines different topics in optical engineering such as optical system design, aberration theory, Fourier optics, and digital image…

  11. Extended sigma-model in nontrivially deformed field-antifield formalism

    NASA Astrophysics Data System (ADS)

    Batalin, Igor A.; Lavrov, Peter M.

    2015-08-01

    We propose an action for the extended sigma-models in the most general setting of the kinetic term allowed in the nontrivially deformed field-antifield formalism. We show that the classical motion equations do naturally take their desired canonical form.

  12. Topological magnetoelectric effects in microwave far-field radiation

    NASA Astrophysics Data System (ADS)

    Berezin, M.; Kamenetskii, E. O.; Shavit, R.

    2016-07-01

    Similar to electromagnetism, described by the Maxwell equations, the physics of magnetoelectric (ME) phenomena deals with the fundamental problem of the relationship between electric and magnetic fields. Despite a formal resemblance between the two notions, they concern effects of different natures. In general, ME-coupling effects manifest in numerous macroscopic phenomena in solids with space and time symmetry breakings. Recently, it was shown that the near fields in the proximity of a small ferrite particle with magnetic-dipolar-mode (MDM) oscillations have the space and time symmetry breakings and the topological properties of these fields are different from the topological properties of the free-space electromagnetic fields. Such MDM-originated fields—called magnetoelectric (ME) fields—carry both spin and orbital angular momenta. They are characterized by power-flow vortices and non-zero helicity. In this paper, we report on observation of the topological ME effects in far-field microwave radiation based on a small microwave antenna with a MDM ferrite resonator. We show that the microwave far-field radiation can be manifested with a torsion structure where an angle between the electric and magnetic field vectors varies. We discuss the question on observation of the regions of localized ME energy in far-field microwave radiation.

  13. STABILITY OF THE TOROIDAL MAGNETIC FIELD IN STELLAR RADIATION ZONES

    SciTech Connect

    Bonanno, Alfio; Urpin, Vadim E-mail: vadim.urpin@uv.es

    2012-03-10

    The stability of the magnetic field in radiation zones is of crucial importance for mixing, angular momentum transport, etc. We consider the stability properties of a star containing a predominant toroidal field in spherical geometry by means of a linear stability in the Boussinesq approximation taking into account the effect of thermal conductivity. We calculate the growth rate of instability and analyze in detail the effects of stable stratification and heat transport. We argue that the stabilizing influence of gravity can never entirely suppress the instability caused by electric currents in radiation zones. However, the stable stratification can essentially decrease the growth rate of instability.

  14. Modern Radiation Therapy for Hodgkin Lymphoma: Field and Dose Guidelines From the International Lymphoma Radiation Oncology Group (ILROG)

    SciTech Connect

    Specht, Lena; Yahalom, Joachim; Illidge, Tim; Berthelsen, Anne Kiil; Constine, Louis S.; Eich, Hans Theodor; Girinsky, Theodore; Hoppe, Richard T.; Mauch, Peter; Mikhaeel, N. George; Ng, Andrea

    2014-07-15

    Radiation therapy (RT) is the most effective single modality for local control of Hodgkin lymphoma (HL) and an important component of therapy for many patients. These guidelines have been developed to address the use of RT in HL in the modern era of combined modality treatment. The role of reduced volumes and doses is addressed, integrating modern imaging with 3-dimensional (3D) planning and advanced techniques of treatment delivery. The previously applied extended field (EF) and original involved field (IF) techniques, which treated larger volumes based on nodal stations, have now been replaced by the use of limited volumes, based solely on detectable nodal (and extranodal extension) involvement at presentation, using contrast-enhanced computed tomography, positron emission tomography/computed tomography, magnetic resonance imaging, or a combination of these techniques. The International Commission on Radiation Units and Measurements concepts of gross tumor volume, clinical target volume, internal target volume, and planning target volume are used for defining the targeted volumes. Newer treatment techniques, including intensity modulated radiation therapy, breath-hold, image guided radiation therapy, and 4-dimensional imaging, should be implemented when their use is expected to decrease significantly the risk for normal tissue damage while still achieving the primary goal of local tumor control. The highly conformal involved node radiation therapy (INRT), recently introduced for patients for whom optimal imaging is available, is explained. A new concept, involved site radiation therapy (ISRT), is introduced as the standard conformal therapy for the scenario, commonly encountered, wherein optimal imaging is not available. There is increasing evidence that RT doses used in the past are higher than necessary for disease control in this era of combined modality therapy. The use of INRT and of lower doses in early-stage HL is supported by available data. Although the

  15. Biaxial Flexural Strength of Poled Lead Zirconate Titanate under High Electric Field with Extended Field Range

    SciTech Connect

    Zhang, Kewei; Zeng, Fan W; Wang, Hong; Lin, Hua-Tay

    2013-01-01

    In the present work, as-received poled lead zirconate titanate, or PZT 5A, was examined using ball-on-ring (BoR) mechanical testing coupled with an electric field. Electric fields in the range of 4Ec (Ec, coercive field) with controlled loading paths were applied, and mechanical tests at a substantial number of characteristic electric field levels were conducted. Commercial electronic liquid FC-40 was used to prevent the setup from dielectric breakdown under a high electric field. Weibull strength distribution was used to interpret the mechanical strength data. The data showed that the strength levels of the PZT-5A tested under OC (open circuit) in air and in FC-40 were almost the same. It was further revealed that , for the studied cases, the effect of loading history on the biaxial flexural strength of the PZT was significant in -Ec, but not in OC or zero field as well as 4Ec . An asymmetry V curve was observed for the characteristic strength-electric field graph, and the bottom of V curve was located near the negative coercive field. Microscopy analysis showed that surface-located volume-distributed flaws were the strength limiter and responsible for the failure of the tested PZT under electromechanical loadings.

  16. Extended gyrokinetic field theory for time-dependent magnetic confinement fields

    NASA Astrophysics Data System (ADS)

    Sugama, H.; Watanabe, T.-H.; Nunami, M.

    2014-01-01

    A gyrokinetic system of equations for turbulent toroidal plasmas in time-dependent axisymmetric background magnetic fields is derived from the variational principle. Besides governing equations for gyrocenter distribution functions and turbulent electromagnetic fields, the conditions which self-consistently determine the background magnetic fields varying on a transport time scale are obtained by using the Lagrangian, which includes the constraint on the background fields. Conservation laws for energy and toroidal angular momentum of the whole system in the time-dependent background magnetic fields are naturally derived by applying Noether's theorem. It is shown that the ensemble-averaged transport equations of particles, energy, and toroidal momentum given in the present work agree with the results from the conventional recursive formulation with the WKB representation except that collisional effects are disregarded here.

  17. Extended gyrokinetic field theory for time-dependent magnetic confinement fields

    SciTech Connect

    Sugama, H.; Watanabe, T.-H.; Nunami, M.

    2014-01-15

    A gyrokinetic system of equations for turbulent toroidal plasmas in time-dependent axisymmetric background magnetic fields is derived from the variational principle. Besides governing equations for gyrocenter distribution functions and turbulent electromagnetic fields, the conditions which self-consistently determine the background magnetic fields varying on a transport time scale are obtained by using the Lagrangian, which includes the constraint on the background fields. Conservation laws for energy and toroidal angular momentum of the whole system in the time-dependent background magnetic fields are naturally derived by applying Noether's theorem. It is shown that the ensemble-averaged transport equations of particles, energy, and toroidal momentum given in the present work agree with the results from the conventional recursive formulation with the WKB representation except that collisional effects are disregarded here.

  18. Bound and Radiation Fields in the Rindler Frame

    NASA Astrophysics Data System (ADS)

    Hirayama, T.

    2001-07-01

    The energy-momentum tensor of the Liénard-Wiechert field is split into bound and emitted parts in the Rindler frame by generalizing the reasoning of Teitelboim applied in the inertial frame [see C. Teitelboim, Phys. Rev. D1 (1970), 1572]. Our analysis proceeds by invoking the concept of ``energy'' defined with respect to the Killing vector field attached to the frame. We obtain the radiation formula in the Rindler frame (the Rindler version of the Larmor formula), and it is found that the radiation power is proportional to the square of the acceleration αμm of the charge relative to the Rindler frame. This result leads us to split the Liénard-Wiechert field into a part II, which is linear in αμ, and a part I, which is independent of αμ. By using these, we split the energy-momentum tensor into two parts. We find that these are properly interpreted as the emitted and bound parts of the tensor in the Rindler frame. In our identification of radiation, a charge radiates neither in the case that the charge is fixed in the Rindler frame, nor in the case that the charge satisfies the equation αμ=0. We then investigate this equation. We consider four gedanken experiments related to the observer dependence of the concept of radiation.

  19. Early Clinical Outcome With Concurrent Chemotherapy and Extended-Field, Intensity-Modulated Radiotherapy for Cervical Cancer

    SciTech Connect

    Beriwal, Sushil . E-mail: beriwals@upmc.edu; Gan, Gregory N.; Heron, Dwight E.; Selvaraj, Raj N.; Kim, Hayeon; Lalonde, Ron; Kelley, Joseph L.; Edwards, Robert P.

    2007-05-01

    Purpose: To assess the early clinical outcomes with concurrent cisplatin and extended-field intensity-modulated radiotherapy (EF-IMRT) for carcinoma of the cervix. Methods and Materials: Thirty-six patients with Stage IB2-IVA cervical cancer treated with EF-IMRT were evaluated. The pelvic lymph nodes were involved in 19 patients, and of these 19 patients, 10 also had para-aortic nodal disease. The treatment volume included the cervix, uterus, parametria, presacral space, upper vagina, and pelvic, common iliac, and para-aortic nodes to the superior border of L1. Patients were assessed for acute toxicities according to the National Cancer Institute Common Toxicity Criteria for Adverse Events, version 3.0. All late toxicities were scored with the Radiation Therapy Oncology Group late toxicity score. Results: All patients completed the prescribed course of EF-IMRT. All but 2 patients received brachytherapy. Median length of treatment was 53 days. The median follow-up was 18 months. Acute Grade {>=}3 gastrointestinal, genitourinary, and myelotoxicity were seen in 1, 1, and 10 patients, respectively. Thirty-four patients had complete response to treatment. Of these 34 patients, 11 developed recurrences. The first site of recurrence was in-field in 2 patients (pelvis in 1, pelvis and para-aortic in 1) and distant in 9 patients. The 2-year actuarial locoregional control, disease-free survival, overall survival, and Grade {>=}3 toxicity rates for the entire cohort were 80%, 51%, 65%, and 10%, respectively. Conclusion: Extended-field IMRT with concurrent chemotherapy was tolerated well, with acceptable acute and early late toxicities. The locoregional control rate was good, with distant metastases being the predominant mode of failure. We are continuing to accrue a larger number of patients and longer follow-up data to further extend our initial observations with this approach.

  20. Extended-gate organic field-effect transistor for the detection of histamine in water

    NASA Astrophysics Data System (ADS)

    Minamiki, Tsukuru; Minami, Tsuyoshi; Yokoyama, Daisuke; Fukuda, Kenjiro; Kumaki, Daisuke; Tokito, Shizuo

    2015-04-01

    As part of our ongoing research program to develop health care sensors based on organic field-effect transistor (OFET) devices, we have attempted to detect histamine using an extended-gate OFET. Histamine is found in spoiled or decayed fish, and causes foodborne illness known as scombroid food poisoning. The new OFET device possesses an extended gate functionalized by carboxyalkanethiol that can interact with histamine. As a result, we have succeeded in detecting histamine in water through a shift in OFET threshold voltage. This result indicates the potential utility of the designed OFET devices in food freshness sensing.

  1. Laser speckle contrast imaging with extended depth of field for in-vivo tissue imaging

    PubMed Central

    Sigal, Iliya; Gad, Raanan; Caravaca-Aguirre, Antonio M.; Atchia, Yaaseen; Conkey, Donald B.; Piestun, Rafael; Levi, Ofer

    2013-01-01

    This work presents, to our knowledge, the first demonstration of the Laser Speckle Contrast Imaging (LSCI) technique with extended depth of field (DOF). We employ wavefront coding on the detected beam to gain quantitative information on flow speeds through a DOF extended two-fold compared to the traditional system. We characterize the system in-vitro using controlled microfluidic experiments, and apply it in-vivo to imaging the somatosensory cortex of a rat, showing improved ability to image flow in a larger number of vessels simultaneously. PMID:24466481

  2. Laser speckle contrast imaging with extended depth of field for in-vivo tissue imaging.

    PubMed

    Sigal, Iliya; Gad, Raanan; Caravaca-Aguirre, Antonio M; Atchia, Yaaseen; Conkey, Donald B; Piestun, Rafael; Levi, Ofer

    2013-12-06

    This work presents, to our knowledge, the first demonstration of the Laser Speckle Contrast Imaging (LSCI) technique with extended depth of field (DOF). We employ wavefront coding on the detected beam to gain quantitative information on flow speeds through a DOF extended two-fold compared to the traditional system. We characterize the system in-vitro using controlled microfluidic experiments, and apply it in-vivo to imaging the somatosensory cortex of a rat, showing improved ability to image flow in a larger number of vessels simultaneously.

  3. Radiation-reaction trapping of electrons in extreme laser fields.

    PubMed

    Ji, L L; Pukhov, A; Kostyukov, I Yu; Shen, B F; Akli, K

    2014-04-11

    A radiation-reaction trapping (RRT) of electrons is revealed in the near-QED regime of laser-plasma interaction. Electrons quivering in laser pulse experience radiation reaction (RR) recoil force by radiating photons. When the laser field reaches the threshold, the RR force becomes significant enough to compensate for the expelling laser ponderomotive force. Then electrons are trapped inside the laser pulse instead of being scattered off transversely and form a dense plasma bunch. The mechanism is demonstrated both by full three-dimensional particle-in-cell simulations using the QED photonic approach and numerical test-particle modeling based on the classical Landau-Lifshitz formula of RR force. Furthermore, the proposed analysis shows that the threshold of laser field amplitude for RRT is approximately the cubic root of laser wavelength over classical electron radius. Because of the pinching effect of the trapped electron bunch, the required laser intensity for RRT can be further reduced.

  4. Study of high speed complex number algorithms. [for determining antenna for field radiation patterns

    NASA Technical Reports Server (NTRS)

    Heisler, R.

    1981-01-01

    A method of evaluating the radiation integral on the curved surface of a reflecting antenna is presented. A three dimensional Fourier transform approach is used to generate a two dimensional radiation cross-section along a planer cut at any angle phi through the far field pattern. Salient to the method is an algorithm for evaluating a subset of the total three dimensional discrete Fourier transform results. The subset elements are selectively evaluated to yield data along a geometric plane of constant. The algorithm is extremely efficient so that computation of the induced surface currents via the physical optics approximation dominates the computer time required to compute a radiation pattern. Application to paraboloid reflectors with off-focus feeds in presented, but the method is easily extended to offset antenna systems and reflectors of arbitrary shapes. Numerical results were computed for both gain and phase and are compared with other published work.

  5. Thermal radiation field of low-temperature sources

    NASA Astrophysics Data System (ADS)

    Łakomy, T.

    1989-05-01

    The asymmetric thermal radiation field of heat sources existing in industry and in the building of apartments has been determined in this work. A description was realised by vector radiant and mean radiant temperatures ( VRT, TMR) obtaining their statistic reciprocal relationships at summer and winter terms.

  6. [Dynamics of biomacromolecules in coherent electromagnetic radiation field].

    PubMed

    Leshcheniuk, N S; Apanasevich, E E; Tereshenkov, V I

    2014-01-01

    It is shown that induced oscillations and periodic displacements of the equilibrium positions occur in biomacromolecules in the absence of electromagnetic radiation absorption, due to modulation of interaction potential between atoms and groups of atoms forming the non-valence bonds in macromolecules by the external electromagnetic field. Such "hyperoscillation" state causes inevitably the changes in biochemical properties of macromolecules and conformational transformation times.

  7. Nanodosimetric Characterization of Mixed Radiation Fields: Status and Perspectives

    NASA Astrophysics Data System (ADS)

    Schulte, Reinhard; Bashkirov, Vladimir; Casiraghi, Margherita

    The nanodosimetric characterization of mixed radiation fields containing variable fluences of charged particles, neutrons, and photons with stochastic quantities related to the number of ionizations in biological targets of nanometric size is an active area of research and development. Applications include measurements in low-dose radiation environments, including outer space, for radiation protection as well as characterization of mixed radiation therapy fields present in particle therapy with protons, light ions, or neutrons. Approaches for the nanodosimetric characterization of mixed radiation fields should consist of balance of theoretical Monte Carlo simulations and experimental studies that can inform each other. The former should be carefully benchmarked with the latter, usually employing detectors filled with low-pressure gas in which nanodosimetric studies are possible. Research in experimental nanodosimetry has exploited the principle of low-pressure-gas scaling of mean interaction distances between energy transfer points up to a million-fold, thus allowing to collect single charges (ions or electrons) generated in cylindrical volumes equivalent to a short segment of DNA. When combined with arrival-time selection, position resolution of down to 5 nm, has been achieved for experimental track structure studies. The results of these experimental studies and Monte Carlo simulations using the Monte Carlo codes will be summarized. More recently, we have studied a new principle of 2D low-energy ion detection by impact ionization in a hole-pattern detector in combination with a low-pressure time projection chamber. First proof-of-principle and performance studies with this track-imaging detector and corresponding Monte Carlo simulations will be presented. The full potential of nanometric quantities in characterizing radiation quality for dosimetry of ionizing radiation is yet to be explored. The most significant signature of radiation quality may be the size and

  8. Unification of gravity and quantum field theory from extended noncommutative geometry

    NASA Astrophysics Data System (ADS)

    Yu, Hefu; Ma, Bo-Qiang

    2017-02-01

    We make biframe and quaternion extensions on the noncommutative geometry, and construct the biframe spacetime for the unification of gravity and quantum field theory (QFT). The extended geometry distinguishes between the ordinary spacetime based on the frame bundle and an extra non-coordinate spacetime based on the biframe bundle constructed by our extensions. The ordinary spacetime frame is globally flat and plays the role as the spacetime frame in which the fields of the Standard Model are defined. The non-coordinate frame is locally flat and is the gravity spacetime frame. The field defined in both frames of such “flat” biframe spacetime can be quantized and plays the role as the gravity field which couples with all the fields to connect the gravity effect with the Standard Model. Thus, we provide a geometric paradigm in which gravity and QFT can be unified.

  9. Effect of Strong Orbital Magnetic Field on the Exciton Condensation in an Extended Falicov Kimball Model

    NASA Astrophysics Data System (ADS)

    Pradhan, S.; Taraphder, A.

    2016-10-01

    A spinless, extended Falicov-Kimball model in the presence of a perpendicular magnetic field is investigated employing a self-consistent mean-field theory in two dimensions. In the presence of the field the excitonic average Δ =< di † fi > is modified: the exciton responds in subtle different ways for different values of the magnetic flux. We examine the effects of Coulomb interaction and hybridization between the localized and itinerant electrons on the excitonic average, for rational values of the applied magnetic field. The excitonic average is found to get enhanced exponentially with the Coulomb interaction while it saturates at large hybridization. The orbital magnetic field suppresses the excitonic average in general, though a strong commensurability effect of the magnetic flux on the behaviour of the excitonic order parameter is observed.

  10. Extended Chiral ({sigma},{pi},{omega}) Mean-Field Model with Vacuum Fluctuation Corrections

    SciTech Connect

    Uechi, Schun T.; Uechi, Hiroshi

    2011-10-21

    Density-dependent relations among saturation properties of symmetric nuclear matter and properties of hadronic stars are discussed by applying the conserving chiral nonlinear ({sigma},{pi},{omega}) mean-field theory. The chiral nonlinear ({sigma},{pi},{omega}) mean-field theory is an extension of the conserving nonlinear (nonchiral){sigma}-{omega} mean-field theory, which is thermodynamically consistent, relativistic and Lorentz-covariant. In the extended chiral ({sigma},{pi},{omega}) mean-field model, all the masses of hadrons are produced by the spontaneous chiral symmetry breaking, which is different from conventional chiral partner models. By comparing both nonchiral and chiral mean-field approximations, the effects of the chiral symmetry breaking mechanism on the mass of {sigma}-meson, coefficients of nonlinear interactions and Fermi-liquid properties are investigated in nuclear matter and neutron stars.

  11. A preliminary study of extended magnetic field structures in the ionosphere

    NASA Technical Reports Server (NTRS)

    Sullivan, James D.; Lane, Barton G.; Post, Richard S.

    1987-01-01

    Several plasma phenomena which are to be expected around a magnet in LEO were identified and analyzed qualitatively. The ASTROMAG cusp magnet will create an extended field whose strength drops to the ambient level over a scale length of approx. 15 m; the combined field has a complex topology with ring nulls and open and closed field lines. The entire configuration is moving through the partially ionized F-layer of the ionosphere at a speed slow compared to the local Alfven speed but fast compared to the ion sound speed. The ambient plasma crosses the extended field structure in a time short compared to the ion Larmor period yet long relative to the electron Larmor period. Thus, electrons behave as a magnetized fluid while ions move ballistically until reflected from higher fields near the cusp. Since the Debye length is short compared to the field scale length, an electrostatic shock-like structure forms to equilibrate the flows and achieve quasi-neutrality. The ambient plasma will be excluded from a cavity near the magnet. The size and nature of the strong interaction region in which the magnet significantly perturbs the ambient flow were determined by studying ion orbits numerically. Lecture viewgraphs summarizing these results are presented.

  12. First phantom and in vivo MPI images with an extended field of view

    NASA Astrophysics Data System (ADS)

    Schmale, I.; Rahmer, J.; Gleich, B.; Kanzenbach, J.; Schmidt, J. D.; Bontus, C.; Woywode, O.; Borgert, J.

    2011-03-01

    Magnetic Particle Imaging (MPI) is a high-potential new medical imaging modality that has been introduced in 2005. MPI uses the non-linear magnetization behavior of iron-oxide based nano-particles, named tracer, to perform quantitative measurements of their local concentration. Previous publications demonstrated the feasibility of real-time in vivo 3D imaging with clinical concentration of Resovist®. Given MPI's fast and sensitive imaging as well as its overall versatility, it has potential to support various medical applications spanning from diagnostics to therapy. As an example, ongoing research investigates the use of MPI in cardiovascular diagnostics for myocardial perfusion measurement. While previous publications reported results from experimental systems with limited bore size (3cm), this contribution presents first phantom and in vivo images acquired on the next hardware generation, an experimental system with an effective bore size of 12cm. The system is designed for pre-clinical studies and can capture image data from an extended field of view compared to the previous, experimental system. The contribution introduces concepts for the encoding of a larger field of view by means of additional magnetic fields, named focus-fields, and outlines the path to stitching of images from multiple focus field settings, called "multi-station reconstruction". To prove the feasibility of imaging of an extended field of view, volumetric images of a moving phantom as well as of a living rat were acquired.

  13. High field CdS detector for infrared radiation

    NASA Technical Reports Server (NTRS)

    Tyagi, R. C.; Robertson, J. B.; Boer, K. W.; Hadley, H. C., Jr. (Inventor)

    1974-01-01

    An infrared radiation detector including a cadmium sulfide platelet having a cathode formed on one of its ends and an anode formed on its other end is presented. The platelet is suitably doped such that stationary high-field domains are formed adjacent the cathode when based in the negative differential conductivity region. A negative potential is applied to the cathode such that a high-field domain is formed adjacent to the cathode. A potential measuring probe is located between the cathode and the anode at the edge of the high-field domain and means are provided for measuring the potential at the probe whereby this measurement is indicative of the infrared radiation striking the platelet.

  14. Extended Gate Field-Effect Transistor Biosensors for Point-Of-Care Testing of Uric Acid.

    PubMed

    Guan, Weihua; Reed, Mark A

    2017-01-01

    An enzyme-free redox potential sensor using off-chip extended-gate field effect transistor (EGFET) with a ferrocenyl-alkanethiol modified gold electrode has been used to quantify uric acid concentration in human serum and urine. Hexacyanoferrate (II) and (III) ions are used as redox reagent. The potentiometric sensor measures the interface potential on the ferrocene immobilized gold electrode, which is modulated by the redox reaction between uric acid and hexacyanoferrate ions. The device shows a near Nernstian response to uric acid and is highly specific to uric acid in human serum and urine. The interference that comes from glucose, bilirubin, ascorbic acid, and hemoglobin is negligible in the normal concentration range of these interferents. The sensor also exhibits excellent long term reliability and is regenerative. This extended gate field effect transistor based sensor is promising for point-of-care detection of uric acid due to the small size, low cost, and low sample volume consumption.

  15. Noise removal in extended depth of field microscope images through nonlinear signal processing.

    PubMed

    Zahreddine, Ramzi N; Cormack, Robert H; Cogswell, Carol J

    2013-04-01

    Extended depth of field (EDF) microscopy, achieved through computational optics, allows for real-time 3D imaging of live cell dynamics. EDF is achieved through a combination of point spread function engineering and digital image processing. A linear Wiener filter has been conventionally used to deconvolve the image, but it suffers from high frequency noise amplification and processing artifacts. A nonlinear processing scheme is proposed which extends the depth of field while minimizing background noise. The nonlinear filter is generated via a training algorithm and an iterative optimizer. Biological microscope images processed with the nonlinear filter show a significant improvement in image quality and signal-to-noise ratio over the conventional linear filter.

  16. Electrical integrity of oxides in a radiation field

    SciTech Connect

    Zinkle, S.J.; Kinoshita, C.

    1996-04-01

    In the absence of an applied electric field, irradiation generally produces a decrease in the permanent (beam-off) electrical conductivity of ceramic insulators. However, in the past 6 years several research groups have reported a phenomenon known as radiation induced electrical degradation (RIED), which produces significant permanent increases in the electrical conductivity of ceramic insulators irradiated with an applied electric field. RIED has been reported to occur at temperatures between 420 and 800 K with applied electric fields as low as 20 V/mm.

  17. Quantum driven dissipative parametric oscillator in a blackbody radiation field

    SciTech Connect

    Pachón, Leonardo A.; Brumer, Paul

    2014-01-15

    We consider the general open system problem of a charged quantum oscillator confined in a harmonic trap, whose frequency can be arbitrarily modulated in time, that interacts with both an incoherent quantized (blackbody) radiation field and with an arbitrary coherent laser field. We assume that the oscillator is initially in thermodynamic equilibrium with its environment, a non-factorized initial density matrix of the system and the environment, and that at t = 0 the modulation of the frequency, the coupling to the incoherent and the coherent radiation are switched on. The subsequent dynamics, induced by the presence of the blackbody radiation, the laser field, and the frequency modulation, is studied in the framework of the influence functional approach. This approach allows incorporating, in analytic closed formulae, the non-Markovian character of the oscillator-environment interaction at any temperature as well the non-Markovian character of the blackbody radiation and its zero-point fluctuations. Expressions for the time evolution of the covariance matrix elements of the quantum fluctuations and the reduced density-operator are obtained.

  18. A characteristic scale in radiation fields of fractal clouds

    SciTech Connect

    Wiscombe, W.; Cahalan, R.; Davis, A.; Marshak, A.

    1996-04-01

    The wavenumber spectrum of Landsat imagery for marine stratocumulus cloud shows a scale break when plotted on a double log plot. We offer an explanation of this scale break in terms of smoothing by horizontal radiative fluxes, which is parameterized and incorporated into an improved pixel approximation. We compute the radiation fields emerging from cloud models with horizontally variable optical depth fractal models. We use comparative spectral and multifractal analysis to qualify the validity of the independent pixel approximation at the largest scales and demonstrate it`s shortcomings on the smallest scales.

  19. Anomalous Radiative Trapping in Laser Fields of Extreme Intensity

    NASA Astrophysics Data System (ADS)

    Gonoskov, A.; Bashinov, A.; Gonoskov, I.; Harvey, C.; Ilderton, A.; Kim, A.; Marklund, M.; Mourou, G.; Sergeev, A.

    2014-07-01

    We demonstrate that charged particles in a sufficiently intense standing wave are compressed toward, and oscillate synchronously at, the antinodes of the electric field. We call this unusual behavior anomalous radiative trapping (ART). We show using dipole pulses, which offer a path to increased laser intensity, that ART opens up new possibilities for the generation of radiation and particle beams, both of which are high energy, directed, and collimated. ART also provides a mechanism for particle control in high-intensity quantum-electrodynamics experiments.

  20. Tunable extended depth of field using a liquid crystal annular spatial filter.

    PubMed

    Klapp, Iftach; Solodar, Asi; Abdulhalim, Ibrahim

    2014-03-15

    A tunable extended depth of field (EDOF) imaging is presented using temporal multiplexing and a low-cost eight-ring, annular liquid crystal spatial light modulator. By changing between different phase profiles in the pupil plane of a lens we perform several levels of EDOF. Using these levels as a "database" it is shown by temporal multiplexing how to decompose tunable levels of EDOF.

  1. Instantaneous three-dimensional sensing using spatial light modulator illumination with extended depth of field imaging

    PubMed Central

    Quirin, Sean; Peterka, Darcy S.; Yuste, Rafael

    2013-01-01

    Imaging three-dimensional structures represents a major challenge for conventional microscopies. Here we describe a Spatial Light Modulator (SLM) microscope that can simultaneously address and image multiple targets in three dimensions. A wavefront coding element and computational image processing enables extended depth-of-field imaging. High-resolution, multi-site three-dimensional targeting and sensing is demonstrated in both transparent and scattering media over a depth range of 300-1,000 microns. PMID:23842387

  2. Microflaring in Low-Lying Core Fields and Extended Coronal Heating in the Quiet Sun

    NASA Technical Reports Server (NTRS)

    Porter, Jason G.; Falconer, D. A.; Moore, Ronald L.

    1999-01-01

    We have previously reported analyses of Yohkoh SXT data examining the relationship between the heating of extended coronal loops (both within and stemming from active regions) and microflaring in core fields lying along neutral lines near their footpoints (J. G. Porter, D. A. Falconer, and R. L. Moore 1998, in Solar Jets and Coronal Plumes, ed. T. Guyenne, ESA SP-421, and references therein). We found a surprisingly poor correlation of intensity variations in the extended loops with individual microflares in the compact heated areas at their feet, despite considerable circumstancial evidence linking the heating processes in these regions. Now, a study of Fe XII image sequences from SOHO EIT show that similar associations of core field structures with the footpoints of very extended coronal features can be found in the quiet Sun. The morphology is consistent with the finding of Wang et al. (1997, ApJ 484, L75) that polar plumes are rooted at sites of mixed polarity in the magnetic network. We find that the upstairs/downstairs intensity variations often follow the trend, identified in the active region observations, of a weak correspondence. Apparently much of the coronal heating in the extended loops is driven by a type of core field magnetic activity that is "cooler" than the events having the coronal signature of microflares, i.e., activity that results in little heating within the core fields themselves. This work was funded by the Solar Physics Branch of NASA's Office of Space Science through the SR&T Program and the SEC Guest Investigator Program.

  3. Compliance with High-Intensity Radiated Fields Regulations - Emitter's Perspective

    NASA Technical Reports Server (NTRS)

    Statman, Joseph; Jamnejad, Vahraz; Nguyen, Lee

    2012-01-01

    NASA's Deep Space Network (DSN) uses high-power transmitters on its large antennas to communicate with spacecraft of NASA and its partner agencies. The prime reflectors of the DSN antennas are parabolic, at 34m and 70m in diameter. The DSN transmitters radiate Continuous Wave (CW) signals at 20 kW - 500 kW at X-band and S-band frequencies. The combination of antenna reflector size and high frequency results in a very narrow beam with extensive oscillating near-field pattern. Another unique feature of the DSN antennas is that they (and the radiated beam) move mostly at very slow sidereal rate, essentially identical in magnitude and at the opposite direction of Earth rotation.The DSN is in the process of revamping its documentation to provide analysis of the High Intensity Radiation Fields (HIRF) environment resulting from radio frequency radiation from DSN antennas for comparison to FAA regulations regarding certification of HIRF protection as outlined in the FAA regulations on HIRF protection for aircraft electrical and electronic systems (Title 14, Code of Federal Regulations (14 CFR) [section sign][section sign] 23.1308, 25.1317, 27.1317, and 29.1317).This paper presents work done at JPL, in consultation with the FAA. The work includes analysis of the radiated field structure created by the unique DSN emitters (combination of transmitters and antennas) and comparing it to the fields defined in the environments in the FAA regulations. The paper identifies areas that required special attention, including the implications of the very narrow beam of the DSN emitters and the sidereal rate motion. The paper derives the maximum emitter power allowed without mitigation and the mitigation zones, where required.Finally, the paper presents summary of the results of the analyses of the DSN emitters and the resulting DSN process documentation.

  4. Radiation hydrodynamics of triggered star formation: the effect of the diffuse radiation field

    NASA Astrophysics Data System (ADS)

    Haworth, Thomas J.; Harries, Tim J.

    2012-02-01

    We investigate the effect of including diffuse field radiation when modelling the radiatively driven implosion of a Bonnor-Ebert sphere (BES). Radiation-hydrodynamical calculations are performed by using operator splitting to combine Monte Carlo photoionization with grid-based Eulerian hydrodynamics that includes self-gravity. It is found that the diffuse field has a significant effect on the nature of radiatively driven collapse which is strongly coupled to the strength of the driving shock that is established before impacting the BES. This can result in either slower or more rapid star formation than expected using the on-the-spot approximation depending on the distance of the BES from the source object. As well as directly compressing the BES, stronger shocks increase the thickness and density in the shell of accumulated material, which leads to short, strong, photoevaporative ejections that reinforce the compression whenever it slows. This happens particularly effectively when the diffuse field is included as rocket motion is induced over a larger area of the shell surface. The formation and evolution of 'elephant trunks' via instability is also found to vary significantly when the diffuse field is included. Since the perturbations that seed instabilities are smeared out elephant trunks form less readily and, once formed, are exposed to enhanced thermal compression.

  5. THE RADIATIVE TRANSFER OF SYNCHROTRON RADIATION THROUGH A COMPRESSED RANDOM MAGNETIC FIELD

    SciTech Connect

    Cawthorne, T. V.; Hughes, P. A.

    2013-07-01

    This paper examines the radiative transfer of synchrotron radiation in the presence of a magnetic field configuration resulting from the compression of a highly disordered magnetic field. It is shown that, provided Faraday rotation and circular polarization can be neglected, the radiative transfer equations for synchrotron radiation separate for this configuration, and the intensities and polarization values for sources that are uniform on large scales can be found straightforwardly in the case where opacity is significant. Although the emission and absorption coefficients must, in general, be obtained numerically, the process is much simpler than a full numerical solution to the transfer equations. Some illustrative results are given and an interesting effect, whereby the polarization increases while the magnetic field distribution becomes less strongly confined to the plane of compression, is discussed. The results are of importance for the interpretation of polarization near the edges of lobes in radio galaxies and of bright features in the parsec-scale jets of active galactic nuclei, where such magnetic field configurations are believed to exist.

  6. First Investigation on the Radiation Field of the Spherical Hohlraum.

    PubMed

    Huo, Wen Yi; Li, Zhichao; Chen, Yao-Hua; Xie, Xuefei; Lan, Ke; Liu, Jie; Ren, Guoli; Li, Yongsheng; Liu, Yonggang; Jiang, Xiaohua; Yang, Dong; Li, Sanwei; Guo, Liang; Zhang, Huan; Hou, Lifei; Du, Huabing; Peng, Xiaoshi; Xu, Tao; Li, Chaoguang; Zhan, Xiayu; Yuan, Guanghui; Zhang, Haijun; Jiang, Baibin; Huang, Lizhen; Du, Kai; Zhao, Runchang; Li, Ping; Wang, Wei; Su, Jingqin; Ding, Yongkun; He, Xian-Tu; Zhang, Weiyan

    2016-07-08

    The first spherical hohlraum energetics experiment is accomplished on the SGIII-prototype laser facility. In the experiment, the radiation temperature is measured by using an array of flat-response x-ray detectors (FXRDs) through a laser entrance hole at four different angles. The radiation temperature and M-band fraction inside the hohlraum are determined by the shock wave technique. The experimental observations indicate that the radiation temperatures measured by the FXRDs depend on the observation angles and are related to the view field. According to the experimental results, the conversion efficiency of the vacuum spherical hohlraum is in the range from 60% to 80%. Although this conversion efficiency is less than the conversion efficiency of the near vacuum hohlraum on the National Ignition Facility, it is consistent with that of the cylindrical hohlraums used on the NOVA and the SGIII-prototype at the same energy scale.

  7. First Investigation on the Radiation Field of the Spherical Hohlraum

    NASA Astrophysics Data System (ADS)

    Huo, Wen Yi; Li, Zhichao; Chen, Yao-Hua; Xie, Xuefei; Lan, Ke; Liu, Jie; Ren, Guoli; Li, Yongsheng; Liu, Yonggang; Jiang, Xiaohua; Yang, Dong; Li, Sanwei; Guo, Liang; Zhang, Huan; Hou, Lifei; Du, Huabing; Peng, Xiaoshi; Xu, Tao; Li, Chaoguang; Zhan, Xiayu; Yuan, Guanghui; Zhang, Haijun; Jiang, Baibin; Huang, Lizhen; Du, Kai; Zhao, Runchang; Li, Ping; Wang, Wei; Su, Jingqin; Ding, Yongkun; He, Xian-Tu; Zhang, Weiyan

    2016-07-01

    The first spherical hohlraum energetics experiment is accomplished on the SGIII-prototype laser facility. In the experiment, the radiation temperature is measured by using an array of flat-response x-ray detectors (FXRDs) through a laser entrance hole at four different angles. The radiation temperature and M -band fraction inside the hohlraum are determined by the shock wave technique. The experimental observations indicate that the radiation temperatures measured by the FXRDs depend on the observation angles and are related to the view field. According to the experimental results, the conversion efficiency of the vacuum spherical hohlraum is in the range from 60% to 80%. Although this conversion efficiency is less than the conversion efficiency of the near vacuum hohlraum on the National Ignition Facility, it is consistent with that of the cylindrical hohlraums used on the NOVA and the SGIII-prototype at the same energy scale.

  8. Mesoscopic near-field radiative heat transfer at low temperatures

    NASA Astrophysics Data System (ADS)

    Maasilta, Ilari; Geng, Zhuoran; Chaudhuri, Saumyadip; Koppinen, Panu

    2015-03-01

    Near-field radiative heat transfer has mostly been discussed at room temperatures and/or macroscopic scale geometries. Here, we discuss our recent theoretical and experimental advances in understanding near-field transfer at ultra-low temperatures below 1K. As the thermal wavelengths increase with lowering temperature, we show that with sensitive tunnel junction bolometers it is possible to study near-field transfer up to distances ~ 10 μm currently, even though the power levels are low. In addition, these type of experiments correspond to the extreme near-field limit, as the near-field region starts at ~ mm distances at 0.1 K, and could have theoretical power enhancement factors of the order of 1010. Preliminary results on heat transfer between two parallel metallic wires are presented. We also comment on possible areas were such heat transfer might be relevant, such as densely packed arrays of low-temperature detectors.

  9. From dinosaurs to modern bird diversity: extending the time scale of adaptive radiation.

    PubMed

    Moen, Daniel; Morlon, Hélène

    2014-05-01

    What explains why some groups of organisms, like birds, are so species rich? And what explains their extraordinary ecological diversity, ranging from large, flightless birds to small migratory species that fly thousand of kilometers every year? These and similar questions have spurred great interest in adaptive radiation, the diversification of ecological traits in a rapidly speciating group of organisms. Although the initial formulation of modern concepts of adaptive radiation arose from consideration of the fossil record, rigorous attempts to identify adaptive radiation in the fossil record are still uncommon. Moreover, most studies of adaptive radiation concern groups that are less than 50 million years old. Thus, it is unclear how important adaptive radiation is over temporal scales that span much larger portions of the history of life. In this issue, Benson et al. test the idea of a "deep-time" adaptive radiation in dinosaurs, compiling and using one of the most comprehensive phylogenetic and body-size datasets for fossils. Using recent phylogenetic statistical methods, they find that in most clades of dinosaurs there is a strong signal of an "early burst" in body-size evolution, a predicted pattern of adaptive radiation in which rapid trait evolution happens early in a group's history and then slows down. They also find that body-size evolution did not slow down in the lineage leading to birds, hinting at why birds survived to the present day and diversified. This paper represents one of the most convincing attempts at understanding deep-time adaptive radiations.

  10. A Computational Model of Cellular Response to Modulated Radiation Fields

    SciTech Connect

    McMahon, Stephen J.; Butterworth, Karl T.; McGarry, Conor K.; Trainor, Colman; O'Sullivan, Joe M.; Hounsell, Alan R.; Prise, Kevin M.

    2012-09-01

    Purpose: To develop a model to describe the response of cell populations to spatially modulated radiation exposures of relevance to advanced radiotherapies. Materials and Methods: A Monte Carlo model of cellular radiation response was developed. This model incorporated damage from both direct radiation and intercellular communication including bystander signaling. The predictions of this model were compared to previously measured survival curves for a normal human fibroblast line (AGO1522) and prostate tumor cells (DU145) exposed to spatially modulated fields. Results: The model was found to be able to accurately reproduce cell survival both in populations which were directly exposed to radiation and those which were outside the primary treatment field. The model predicts that the bystander effect makes a significant contribution to cell killing even in uniformly irradiated cells. The bystander effect contribution varies strongly with dose, falling from a high of 80% at low doses to 25% and 50% at 4 Gy for AGO1522 and DU145 cells, respectively. This was verified using the inducible nitric oxide synthase inhibitor aminoguanidine to inhibit the bystander effect in cells exposed to different doses, which showed significantly larger reductions in cell killing at lower doses. Conclusions: The model presented in this work accurately reproduces cell survival following modulated radiation exposures, both in and out of the primary treatment field, by incorporating a bystander component. In addition, the model suggests that the bystander effect is responsible for a significant portion of cell killing in uniformly irradiated cells, 50% and 70% at doses of 2 Gy in AGO1522 and DU145 cells, respectively. This description is a significant departure from accepted radiobiological models and may have a significant impact on optimization of treatment planning approaches if proven to be applicable in vivo.

  11. Ionizing Radiation Effects on Graphene Based Field Effects Transistors

    NASA Astrophysics Data System (ADS)

    Alexandrou, Konstantinos

    Graphene, first isolated in 2004 by Andre Geim and Konstantin Novoselov, is an atomically thin two-dimensional layer of hexagonal carbon that has been extensively studied due to its unique electronic, mechanical, thermal and optical properties. Its vast potential has led to the development of a wide variety of novel devices such as, transistors, solar cells, batteries and sensors that offer significant advantages over the conventional microelectronic ones. Although graphene-based devices show very promising performance characteristics, limited has been done in order to evaluate how these devices operate in a radiation harsh environment. Undesirable phenomena such as total dose effects, single event upsets, displacement damage and soft errors that silicon-based devices are prone to, can have a detrimental impact on performance and reliability. Similarly, the significant effects of irradiation on carbon nanotubes indicate the potential for related radiation induced defects in carbon-based materials, such as graphene. In this work, we fabricate graphene field effect transistors (GFETs) and systematically study the various effects of ionizing radiation on the material and device level. Graphene grown by chemical vapor deposition (CVD) along with standard lithographic and shadow masking techniques, was used for the transistor fabrication. GFETs were subjected to different radiation sources, such as, beta particles (electron radiation), gamma (photons) and ions (alpha, protons and Fe particles) under various radiation doses and energies. The effects on graphene's crystal structure, transport properties and doping profile were examined by using a variety of characterization tools and techniques. We demonstrate not only the mechanisms of ionized charge build up in the substrate and displacement damage effects on GFET performance, but also that atmospheric adsorbents from the surrounding environment can have a significant impact on the radiation hardness of graphene. We

  12. Near field wireless power transfer using curved relay resonators for extended transfer distance

    NASA Astrophysics Data System (ADS)

    Zhu, D.; Clare, L.; Stark, B. H.; Beeby, S. P.

    2015-12-01

    This paper investigates the performance of a near field wireless power transfer system that uses curved relay resonator to extend transfer distance. Near field wireless power transfer operates based on the near-field electromagnetic coupling of coils. Such a system can transfer energy over a relatively short distance which is of the same order of dimensions of the coupled coils. The energy transfer distance can be increased using flat relay resonators. Recent developments in printing electronics and e-textiles have seen increasing demand of embedding electronics into fabrics. Near field wireless power transfer is one of the most promising methods to power electronics on fabrics. The concept can be applied to body-worn textiles by, for example, integrating a transmitter coil into upholstery, and a flexible receiver coil into garments. Flexible textile coils take on the shape of the supporting materials such as garments, and therefore curved resonator and receiver coils are investigated in this work. Experimental results showed that using curved relay resonator can effectively extend the wireless power transfer distance. However, as the curvature of the coil increases, the performance of the wireless power transfer, especially the maximum received power, deteriorates.

  13. Extended Depth of Field for High-Resolution Scanning Transmission Electron Microscopy

    SciTech Connect

    Hovden, Robert; Xin, Huolin L.; Muller, David A.

    2010-12-02

    Aberration-corrected scanning transmission electron microscopes (STEMs) provide sub-Angstrom lateral resolution; however, the large convergence angle greatly reduces the depth of field. For microscopes with a small depth of field, information outside of the focal plane quickly becomes blurred and less defined. It may not be possible to image some samples entirely in focus. Extended depth-of-field techniques, however, allow a single image, with all areas in focus, to be extracted from a series of images focused at a range of depths. In recent years, a variety of algorithmic approaches have been employed for bright-field optical microscopy. Here, we demonstrate that some established optical microscopy methods can also be applied to extend the ~6 nm depth of focus of a 100 kV 5th-order aberration-corrected STEM (α{sub max} = 33 mrad) to image Pt-Co nanoparticles on a thick vulcanized carbon support. These techniques allow us to automatically obtain a single image with all the particles in focus as well as a complimentary topography map.

  14. Extended depth of field for high-resolution scanning transmission electron microscopy.

    PubMed

    Hovden, Robert; Xin, Huolin L; Muller, David A

    2011-02-01

    Aberration-corrected scanning transmission electron microscopes (STEMs) provide sub-Angstrom lateral resolution; however, the large convergence angle greatly reduces the depth of field. For microscopes with a small depth of field, information outside of the focal plane quickly becomes blurred and less defined. It may not be possible to image some samples entirely in focus. Extended depth-of-field techniques, however, allow a single image, with all areas in focus, to be extracted from a series of images focused at a range of depths. In recent years, a variety of algorithmic approaches have been employed for bright-field optical microscopy. Here, we demonstrate that some established optical microscopy methods can also be applied to extend the ∼ 6 nm depth of focus of a 100 kV 5th-order aberration-corrected STEM (α max = 33 mrad) to image Pt-Co nanoparticles on a thick vulcanized carbon support. These techniques allow us to automatically obtain a single image with all the particles in focus as well as a complimentary topography map.

  15. Near-field radiative heat transfer between metamaterial thin films.

    PubMed

    Basu, Soumyadipta; Francoeur, Mathieu

    2014-03-01

    We investigate near-field radiative heat transfer between two thin films made of metamaterials. The impact of film thickness on magnetic and electric surface polaritons (ESPs) is analyzed. It is found that the strength as well as the location of magnetic resonance does not change with film thickness until the film behaves as semi-infinite for the dielectric function chosen in this study. When the film is thinner than vacuum gap, both electric and magnetic polaritons contribute evenly to near-field radiative heat transfer. At larger film thicknesses, ESPs dominate heat transfer due to excitation of a larger number of modes. Results obtained from this study will facilitate applications of metamaterials as thin-film coatings for energy systems.

  16. Analysis of the radiated information in spinning sound fields.

    PubMed

    Carley, Michael

    2010-10-01

    The information content of a spinning sound field is analyzed using a combination of exact and asymptotic results, in order to set limits on how accurately source identification can be carried out. Using a transformation of the circular source to an exactly equivalent set of line source modes, given by Chebyshev polynomials, it is found that the line source modes of order greater than the source wavenumber generate exponentially small fields. Asymptotic analysis shows that the remaining, lower order, modes radiate efficiently only into a region around the source plane, with this region shrinking as the mode order is increased. The results explain the ill-conditioning of source identification methods; the successful use of low order models in active noise control; and the low radiation efficiency of subsonic jets.

  17. CONCORD: comparison of cosmic radiation detectors in the radiation field at aviation altitudes

    NASA Astrophysics Data System (ADS)

    Meier, Matthias M.; Trompier, François; Ambrozova, Iva; Kubancak, Jan; Matthiä, Daniel; Ploc, Ondrej; Santen, Nicole; Wirtz, Michael

    2016-05-01

    Space weather can strongly affect the complex radiation field at aviation altitudes. The assessment of the corresponding radiation exposure of aircrew and passengers has been a challenging task as well as a legal obligation in the European Union for many years. The response of several radiation measuring instruments operated by different European research groups during joint measuring flights was investigated in the framework of the CONCORD (COmparisoN of COsmic Radiation Detectors) campaign in the radiation field at aviation altitudes. This cooperation offered the opportunity to measure under the same space weather conditions and contributed to an independent quality control among the participating groups. The CONCORD flight campaign was performed with the twin-jet research aircraft Dassault Falcon 20E operated by the flight facility Oberpfaffenhofen of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR). Dose rates were measured at four positions in the atmosphere in European airspace for about one hour at each position in order to obtain acceptable counting statistics. The analysis of the space weather situation during the measuring flights demonstrates that short-term solar activity did not affect the results which show a very good agreement between the readings of the instruments of the different institutes.

  18. Radiation engineering of optical antennas for maximum field enhancement.

    PubMed

    Seok, Tae Joon; Jamshidi, Arash; Kim, Myungki; Dhuey, Scott; Lakhani, Amit; Choo, Hyuck; Schuck, Peter James; Cabrini, Stefano; Schwartzberg, Adam M; Bokor, Jeffrey; Yablonovitch, Eli; Wu, Ming C

    2011-07-13

    Optical antennas have generated much interest in recent years due to their ability to focus optical energy beyond the diffraction limit, benefiting a broad range of applications such as sensitive photodetection, magnetic storage, and surface-enhanced Raman spectroscopy. To achieve the maximum field enhancement for an optical antenna, parameters such as the antenna dimensions, loading conditions, and coupling efficiency have been previously studied. Here, we present a framework, based on coupled-mode theory, to achieve maximum field enhancement in optical antennas through optimization of optical antennas' radiation characteristics. We demonstrate that the optimum condition is achieved when the radiation quality factor (Q(rad)) of optical antennas is matched to their absorption quality factor (Q(abs)). We achieve this condition experimentally by fabricating the optical antennas on a dielectric (SiO(2)) coated ground plane (metal substrate) and controlling the antenna radiation through optimizing the dielectric thickness. The dielectric thickness at which the matching condition occurs is approximately half of the quarter-wavelength thickness, typically used to achieve constructive interference, and leads to ∼20% higher field enhancement relative to a quarter-wavelength thick dielectric layer.

  19. Pedagogical systematic derivation of Noether point symmetries in special relativistic field theories and extended gravity cosmology

    NASA Astrophysics Data System (ADS)

    Haas, Fernando

    2016-11-01

    A didactic and systematic derivation of Noether point symmetries and conserved currents is put forward in special relativistic field theories, without a priori assumptions about the transformation laws. Given the Lagrangian density, the invariance condition develops as a set of partial differential equations determining the symmetry transformation. The solution is provided in the case of real scalar, complex scalar, free electromagnetic, and charged electromagnetic fields. Besides the usual conservation laws, a less popular symmetry is analyzed: the symmetry associated with the linear superposition of solutions, whenever applicable. The role of gauge invariance is emphasized. The case of the charged scalar particle under external electromagnetic fields is considered, and the accompanying Noether point symmetries determined. Noether point symmetries for a dynamical system in extended gravity cosmology are also deduced.

  20. Extended dynamical mean-field study of the Hubbard model with long-range interactions

    NASA Astrophysics Data System (ADS)

    Huang, Li; Ayral, Thomas; Biermann, Silke; Werner, Philipp

    2014-11-01

    Using extended dynamical mean-field theory and its combination with the G W approximation, we compute the phase diagrams and local spectral functions of the single-band extended Hubbard model on the square and simple cubic lattices, considering long-range interactions up to the third nearest neighbors. The longer-range interactions shift the boundaries between the metallic, charge-ordered insulating, and Mott insulating phases, and lead to characteristic changes in the screening modes and local spectral functions. Momentum-dependent self-energy contributions enhance the correlation effects and thus compete with the additional screening effect from longer-range Coulomb interactions. Our results suggest that the influence of longer-range intersite interactions is significant, and that these effects deserve attention in realistic studies of correlated materials.

  1. Conservation of ζ with radiative corrections from heavy field

    SciTech Connect

    Tanaka, Takahiro; Urakawa, Yuko

    2016-06-08

    In this paper, we address a possible impact of radiative corrections from a heavy scalar field χ on the curvature perturbation ζ. Integrating out χ, we derive the effective action for ζ, which includes the loop corrections of the heavy field χ. When the mass of χ is much larger than the Hubble scale H, the loop corrections of χ only yield a local contribution to the effective action and hence the effective action simply gives an action for ζ in a single field model, where, as is widely known, ζ is conserved in time after the Hubble crossing time. Meanwhile, when the mass of χ is comparable to H, the loop corrections of χ can give a non-local contribution to the effective action. Because of the non-local contribution from χ, in general, ζ may not be conserved, even if the classical background trajectory is determined only by the evolution of the inflaton. In this paper, we derive the condition that ζ is conserved in time in the presence of the radiative corrections from χ. Namely, we show that when the dilatation invariance, which is a part of the diffeomorphism invariance, is preserved at the quantum level, the loop corrections of the massive field χ do not disturb the constant evolution of ζ at super Hubble scales. In this discussion, we show the Ward-Takahashi identity for the dilatation invariance, which yields a consistency relation for the correlation functions of the massive field χ.

  2. Radiation from electrons in graphene in strong electric field

    SciTech Connect

    Yokomizo, N.

    2014-12-15

    We study the interaction of electrons in graphene with the quantized electromagnetic field in the presence of an applied uniform electric field using the Dirac model of graphene. Electronic states are represented by exact solutions of the Dirac equation in the electric background, and amplitudes of first-order Feynman diagrams describing the interaction with the photon field are calculated for massive Dirac particles in both valleys. Photon emission probabilities from a single electron and from a many-electron system at the charge neutrality point are derived, including the angular and frequency dependence, and several limiting cases are analyzed. The pattern of photon emission at the Dirac point in a strong field is determined by an interplay between the nonperturbative creation of electron–hole pairs and spontaneous emission, allowing for the possibility of observing the Schwinger effect in measurements of the radiation emitted by pristine graphene under DC voltage.

  3. Exciton condensation in an extended Falicov-Kimball model in the presence of orbital magnetic fields

    NASA Astrophysics Data System (ADS)

    Pradhan, Subhasree; Taraphder, A.

    2016-12-01

    We investigate the exciton condensation in the presence of an external, perpendicular magnetic field in a two-dimensional extended spinless Falicov-Kimball model involving itinerant (c) and localized (f) electrons in the half-filled limit, using self-consistent, mean-field approximations. On tuning the orbital magnetic field the excitonic averages Δi =< c_i^\\dagger f_i> are affected in several ways: the external field usually suppresses the excitonic average but we find that it is also possible to enhance excitonic response at some values of the magnetic field. We further examine the effect of Coulomb interaction and the f-electron hopping on the condensation of excitons for some rational values of the applied magnetic fields. The interband Coulomb interaction enhances Δ exponentially and the effect is more pronounced for low hybridization. The strength of excitonic average drops when f-electrons have a dispersion. This trend is independent of the relative sign of the c- and f-electron hopping; although the excitonic response is different for different parity of the c- and f-electrons.

  4. Digital approximation to extended depth of field in no telecentric imaging systems

    NASA Astrophysics Data System (ADS)

    Meneses, J. E.; Contreras, C. R.

    2011-01-01

    A method used to digitally extend the depth of field of an imaging system consists to move the object of study along the optical axis of the system and different images will contain different areas that are sharp; those images are stored and processed digitally to obtain a fused image, in that image will be sharp all regions of the object. The implementation of this method, although widely used, imposes certain experimental conditions that should be evaluated for to study the degree of validity of the image final obtained. An experimental condition is related with the conservation of the geometric magnification factor when there is a relative movement between the object and the observation system; this implies that the system must be telecentric, which leads to a reduction of the observation field and the use of expensive systems if the application includes microscopic observation. This paper presents a technique that makes possible to extend depth of filed of an imaging system non telecentric; this system is used to realize applications in Optical Metrology with systems that have great observation field.

  5. Infrared Faint Radio Sources in the Extended Chandra Deep Field South

    NASA Astrophysics Data System (ADS)

    Huynh, Minh T.

    2009-01-01

    Infrared-Faint Radio Sources (IFRSs) are a class of radio objects found in the Australia Telescope Large Area Survey (ATLAS) which have no observable counterpart in the Spitzer Wide-area Infrared Extragalactic Survey (SWIRE). The extended Chandra Deep Field South now has even deeper Spitzer imaging (3.6 to 70 micron) from a number of Legacy surveys. We report the detections of two IFRS sources in IRAC images. The non-detection of two other IFRSs allows us to constrain the source type. Detailed modeling of the SED of these objects shows that they are consistent with high redshift AGN (z > 2).

  6. Extending the standard model effective field theory with the complete set of dimension-7 operators

    NASA Astrophysics Data System (ADS)

    Lehman, Landon

    2014-12-01

    We present a complete list of the independent dimension-7 operators that are constructed using the standard model degrees of freedom and are invariant under the standard model gauge group. This list contains only 20 independent operators, far fewer than the 63 operators available at dimension 6. All of these dimension-7 operators contain fermions and violate lepton number, and 7 of the 20 violate baryon number as well. This result extends the standard model effective field theory and allows a more detailed exploration of the structure and properties of possible deformations from the standard model Lagrangian.

  7. Measurement of Radiation - Light Field Congruence using a Photodiode Array

    NASA Astrophysics Data System (ADS)

    Balderson, Michael J.

    Improved treatment techniques in radiation therapy provide incentive to reduce treatment margins, thereby increasing the necessity for more accurate geometrical setup of the linear accelerator and accompanying components. In this thesis, we describe the development of a novel device that enables precise and automated measurement of radiation-light field congruence of medical linear accelerators for the purpose of improving setup accuracy, and standardizing repeated quality control activities. The device consists of a silicon photodiode array, an evaluation board, a data acquisition card, and a laptop. Using the device, we show that the radiation-light field congruence for both 6 and 15 MV beams is within 2 mm on a Varian Clinac 21 EX medical linear accelerator. Because measurements are automated, ambiguities resulting from observer variability are removed, greatly improving the reproducibility of measurements over time and across observers. We expect the device to be useful in providing consistent measurements on linear accelerators used for stereotactic radiosurgery, during the commissioning of new linear accelerators, and as an alternative to film or other commercially available devices for performing monthly or annual quality control checks.

  8. Conference on Atmospheric Radiation, 6th, Williamsburg, VA, May 13-16, 1986, Extended Abstracts

    SciTech Connect

    Not Available

    1986-01-01

    Numerous topics of interest for measurements and modeling of radiation in the atmosphere are discussed, with emphasis on satellite remote sensing capabilities, data analysis techniques and climatological impact. Attention is devoted to aerosols at all levels of the atmosphere, the current understanding of potential nuclear winter scenarios, and to instruments which are used for sensing radiance in the atmosphere. Consideration is also given to spectroscopy and band models, radiative transfer calculations, earth radiation budget (ERB) models and their interaction with GCMs, and to climate models. In-depth analyses are performed of data from the ERB instruments on the Nimbus-7 spacecraft and to validation procedures being developed for data collected by the ERB satellite.

  9. Extended-Gate Metal Oxide Semiconductor Field Effect Transistor-Based Biosensor for Detection of Deoxynivalenol

    NASA Astrophysics Data System (ADS)

    Kwon, Insu; Lee, Hee-Ho; Choi, Jinhyeon; Shin, Jang-Kyoo; Seo, Sang-Ho; Choi, Sung-Wook; Chun, Hyang Sook

    2011-06-01

    In this work, we present an extended-gate metal oxide semiconductor field effect transistor (MOSFET)-based biosensor for the detection of deoxynivalenol using a null-balancing circuit. An extended-gate MOSFET-based biosensor was fabricated by a standard complementary metal oxide semiconductor (CMOS) process and its characteristics were measured. A null-balancing circuit was used to measure the output voltage of the sensor directly, instead of measuring the drain current of the sensor. Au was used as the gate metal, which has a chemical affinity with thiol, which leads to the immobilization of a self-assembled monolayer (SAM) of mercaptohexadecanoic acid (MHDA). The SAM was used to immobilize the anti-deoxynivalenol antibody. The carboxyl group of the SAM was bound to the anti-deoxynivalenol antibody. The anti-deoxynivalenol antibody and deoxynivalenol were bound by their antigen-antibody reaction. The measurements were performed in phosphate buffered saline (PBS; pH 7.4) solution. A standard Ag/AgCl electrode was employed as a reference electrode. The bindings of a SAM, anti-deoxynivalenol antibody, and deoxynivalenol caused a variation in the output voltage of the extended-gate MOSFET-based biosensor. Surface plasmon resonance (SPR) measurement was performed to verify the interaction among the SAM, deoxynivalenol-antibody, and deoxynivalenol.

  10. Calcium imaging of neural circuits with extended depth-of-field light-sheet microscopy.

    PubMed

    Quirin, Sean; Vladimirov, Nikita; Yang, Chao-Tsung; Peterka, Darcy S; Yuste, Rafael; Ahrens, Misha B

    2016-03-01

    Increasing the volumetric imaging speed of light-sheet microscopy will improve its ability to detect fast changes in neural activity. Here, a system is introduced for brain-wide imaging of neural activity in the larval zebrafish by coupling structured illumination with cubic phase extended depth-of-field (EDoF) pupil encoding. This microscope enables faster light-sheet imaging and facilitates arbitrary plane scanning-removing constraints on acquisition speed, alignment tolerances, and physical motion near the sample. The usefulness of this method is demonstrated by performing multi-plane calcium imaging in the fish brain with a 416×832×160  μm field of view at 33 Hz. The optomotor response behavior of the zebrafish is monitored at high speeds, and time-locked correlations of neuronal activity are resolved across its brain.

  11. A field test of a simple stochastic radiative transfer model

    SciTech Connect

    Byrne, N.

    1995-09-01

    The problem of determining the effect of clouds on the radiative energy balance of the globe is of well-recognized importance. One can in principle solve the problem for any given configuration of clouds using numerical techniques. This knowledge is not useful however, because of the amount of input data and computer resources required. Besides, we need only the average of the resulting solution over the grid scale of a general circulation model (GCM). Therefore, we are interested in estimating the average of the solutions of such fine-grained problems using only coarse grained data, a science or art called stochastic radiation transfer. Results of the described field test indicate that the stochastic description is a somewhat better fit to the data than is a fractional cloud cover model, but more data are needed. 1 ref., 3 figs.

  12. Total variation based image deconvolution for extended depth-of-field microscopy images

    NASA Astrophysics Data System (ADS)

    Hausser, F.; Beckers, I.; Gierlak, M.; Kahraman, O.

    2015-03-01

    One approach for a detailed understanding of dynamical cellular processes during drug delivery is the use of functionalized biocompatible nanoparticles and fluorescent markers. An appropriate imaging system has to detect these moving particles so as whole cell volumes in real time with high lateral resolution in a range of a few 100 nm. In a previous study Extended depth-of-field microscopy (EDF-microscopy) has been applied to fluorescent beads and tradiscantia stamen hair cells and the concept of real-time imaging has been proved in different microscopic modes. In principle a phase retardation system like a programmable space light modulator or a static waveplate is incorporated in the light path and modulates the wavefront of light. Hence the focal ellipsoid is smeared out and images seem to be blurred in a first step. An image restoration by deconvolution using the known point-spread-function (PSF) of the optical system is necessary to achieve sharp microscopic images of an extended depth-of-field. This work is focused on the investigation and optimization of deconvolution algorithms to solve this restoration problem satisfactorily. This inverse problem is challenging due to presence of Poisson distributed noise and Gaussian noise, and since the PSF used for deconvolution exactly fits in just one plane within the object. We use non-linear Total Variation based image restoration techniques, where different types of noise can be treated properly. Various algorithms are evaluated for artificially generated 3D images as well as for fluorescence measurements of BPAE cells.

  13. Field Deployable Gamma Radiation Detectors for DHS Use

    SciTech Connect

    Sanjoy Mukhopadhyay

    2007-08-01

    Recently, the Department of Homeland Security (DHS) has integrated all nuclear detection research, development, testing, evaluation, acquisition, and operational support into a single office: the Domestic Nuclear Detection Office (DNDO). The DNDO has specific requirements set for all commercial off-the-shelf and government off-the-shelf radiation detection equipment and data acquisition systems. This article would investigate several recent developments in field deployable gamma radiation detectors that are attempting to meet the DNDO specifications. Commercially available, transportable, handheld radio isotope identification devices (RIID) are inadequate for DHS requirements in terms of sensitivity, resolution, response time, and reach-back capability. The leading commercial vendor manufacturing handheld gamma spectrometer in the United States is Thermo Electron Corporation. Thermo Electron's identiFINDER{trademark}, which primarily uses sodium iodide crystals (3.18 x 2.54cm cylinders) as gamma detectors, has a Full-Width-at-Half-Maximum energy resolution of 7 percent at 662 keV. Thermo Electron has just recently come up with a reach-back capability patented as RadReachBack{trademark} that enables emergency personnel to obtain real-time technical analysis of radiation samples they find in the field. The current project has the goal to build a prototype handheld gamma spectrometer, equipped with a digital camera and an embedded cell phone to be used as an RIID with higher sensitivity, better resolution, and faster response time (able to detect the presence of gamma-emitting radio isotopes within 5 seconds of approach), which will make it useful as a field deployable tool. The handheld equipment continuously monitors the ambient gamma radiation, and, if it comes across any radiation anomalies with higher than normal gamma gross counts, it sets an alarm condition. When a substantial alarm level is reached, the system automatically triggers the saving of relevant

  14. Field Deployable Gamma Radiation Detectors for DHS Use

    SciTech Connect

    Sanjoy Mukhopadhyay

    2007-08-31

    Recently, the U.S. Department of Homeland Security (DHS) has integrated all nuclear detection research, development, testing, evaluation, acquisition, and operational support into a single office: the Domestic Nuclear Detection Office (DNDO). The DNDO has specific requirements set for all commercial and government off-the-shelf radiation detection equipment and data acquisition systems. This article would investigate several recent developments in field deployable gamma radiation detectors that are attempting to meet the DNDO specifications. Commercially available, transportable, handheld radio isotope identification devices (RIID) are inadequate for DHS’s requirements in terms of sensitivity, resolution, response time and reach back capability. The leading commercial vendor manufacturing handheld gamma spectrometer in the United States is Thermo Electron Corporation. Thermo Electron’s identiFINDER™, which primarily uses sodium iodide crystals (3.18-cm x 2.54-cm cylinders) as gamma detector, has a Full-Width-at-Half-Maximum energy resolution of 7 percent at 662 keV. Thermo Electron has just recently come up with a reach-back capability patented as RadReachBack™ that enables emergency personnel to obtain real-time technical analysis of radiation samples they find in the field. The current project has the goal to build a prototype handheld gamma spectrometer, equipped with a digital camera and an embedded cell phone to be used as an RIID with higher sensitivity (comparable to that of a 7.62-cm x 7.62-cm sodium iodide crystal at low gamma energy ranging from 30 keV to 3,000 keV), better resolution (< 3.0 percent at 662 keV), faster response time (able to detect the presence of gamma-emitting radio isotopes within 5 seconds of approach), which will make it useful as a field deployable tool. The handheld equipment continuously monitors the ambient gamma radiation and, if it comes across any radiation anomalies with higher than normal gamma gross counts, it sets

  15. Field-deployable gamma-radiation detectors for DHS use

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Sanjoy

    2007-09-01

    Recently, the Department of Homeland Security (DHS) has integrated all nuclear detection research, development, testing, evaluation, acquisition, and operational support into a single office: the Domestic Nuclear Detection Office (DNDO). The DNDO has specific requirements set for all commercial off-the-shelf and government off-the-shelf radiation detection equipment and data acquisition systems. This article would investigate several recent developments in field deployable gamma radiation detectors that are attempting to meet the DNDO specifications. Commercially available, transportable, handheld radio isotope identification devices (RIID) are inadequate for DHS' requirements in terms of sensitivity, resolution, response time, and reach-back capability. The leading commercial vendor manufacturing handheld gamma spectrometer in the United States is Thermo Electron Corporation. Thermo Electron's identiFINDER TM, which primarily uses sodium iodide crystals (3.18 x 2.54cm cylinders) as gamma detectors, has a Full-Width-at-Half-Maximum energy resolution of 7 percent at 662 keV. Thermo Electron has just recently come up with a reach-back capability patented as RadReachBack TM that enables emergency personnel to obtain real-time technical analysis of radiation samples they find in the field1. The current project has the goal to build a prototype handheld gamma spectrometer, equipped with a digital camera and an embedded cell phone to be used as an RIID with higher sensitivity, better resolution, and faster response time (able to detect the presence of gamma-emitting radio isotopes within 5 seconds of approach), which will make it useful as a field deployable tool. The handheld equipment continuously monitors the ambient gamma radiation, and, if it comes across any radiation anomalies with higher than normal gamma gross counts, it sets an alarm condition. When a substantial alarm level is reached, the system automatically triggers the saving of relevant spectral data and

  16. Radiation-like scalar field and gauge fields in cosmology for a theory with dynamical time

    NASA Astrophysics Data System (ADS)

    Benisty, David; Guendelman, E. I.

    2016-09-01

    Cosmological solutions with a scalar field behaving as radiation are obtained, in the context of gravitational theory with dynamical time. The solution requires the spacial curvature of the universe k, to be zero, unlike the standard radiation solutions, which do not impose any constraint on the spatial curvature of the universe. This is because only such k = 0 radiation solutions pose a homothetic Killing vector. This kind of theory can be used to generalize electromagnetism and other gauge theories, in curved spacetime, and there are no deviations from standard gauge field equation (like Maxwell equations) in the case there exist a conformal Killing vector. But there could be departures from Maxwell and Yang-Mills equations, for more general spacetimes.

  17. Intercomparison of radiation protection instrumentation in a pulsed neutron field

    NASA Astrophysics Data System (ADS)

    Caresana, M.; Denker, A.; Esposito, A.; Ferrarini, M.; Golnik, N.; Hohmann, E.; Leuschner, A.; Luszik-Bhadra, M.; Manessi, G.; Mayer, S.; Ott, K.; Röhrich, J.; Silari, M.; Trompier, F.; Volnhals, M.; Wielunski, M.

    2014-02-01

    In the framework of the EURADOS working group 11, an intercomparison of active neutron survey meters was performed in a pulsed neutron field (PNF). The aim of the exercise was to evaluate the performances of various neutron instruments, including commercially available rem-counters, personal dosemeters and instrument prototypes. The measurements took place at the cyclotron of the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH. The cyclotron is routinely used for proton therapy of ocular tumours, but an experimental area is also available. For the therapy the machine accelerates protons to 68 MeV. The interaction of the proton beam with a thick tungsten target produces a neutron field with energy up to about 60 MeV. One interesting feature of the cyclotron is that the beam can be delivered in bursts, with the possibility to modify in a simple and flexible way the burst length and the ion current. Through this possibility one can obtain radiation bursts of variable duration and intensity. All instruments were placed in a reference position and irradiated with neutrons delivered in bursts of different intensity. The analysis of the instrument response as a function of the burst charge (the total electric charge of the protons in the burst shot onto the tungsten target) permitted to assess for each device the dose underestimation due to the time structure of the radiation field. The personal neutron dosemeters were exposed on a standard PMMA slab phantom and the response linearity was evaluated.

  18. Thermal electron acceleration by electric field spikes in the outer radiation belt: generation of field-aligned pitch angle distributions

    NASA Astrophysics Data System (ADS)

    Vasko, I.; Agapitov, O. V.; Mozer, F.; Artemyev, A.

    2015-12-01

    Van Allen Probes observations in the outer radiation belt have demonstrated an abundance non-linear electrostatic stucture called Time Domain Structures (TDS). One of the type of TDS is electrostatic electron-acoustic double layers (DL). Observed DLs are frequently accompanied by field-aligned (bi-directional) pitch angle distributions (PAD) of electrons with energies from hundred eVs up to several keV (rarely up to tens of keV). We perform numerical simulations of the DL interaction with thermal electrons making use of the test particle approach. DL parameters assumed in the simulations are adopted from observations. We show that DLs accelerate thermal electrons parallel to the magnetic field via the electrostatic Fermi mechanism, i.e. due to reflections from DL potential humps. Due to this interaction some fraction of electrons is scattered into the loss cone. The electron energy gain is larger for larger DL scalar potential amplitudes and higher propagation velocities. In addition to the Fermi mechanism electrons can be trapped by DLs in their generation region and accelerated due to transport to higher latitudes. Both mechanisms result in formation of field-aligned PADs for electrons with energies comparable to those found in observations. The Fermi mechanism provides field-aligned PADs for <1 keV electrons, while the trapping mechanism extends field-aligned PADs to higher energy electrons.

  19. Thermal electron acceleration by electric field spikes in the outer radiation belt: Generation of field-aligned pitch angle distributions

    NASA Astrophysics Data System (ADS)

    Vasko, I. Y.; Agapitov, O. V.; Mozer, F. S.; Artemyev, A. V.

    2015-10-01

    Van Allen Probes observations in the outer radiation belt have demonstrated an abundance of electrostatic electron-acoustic double layers (DL). DLs are frequently accompanied by field-aligned (bidirectional) pitch angle distributions (PAD) of electrons with energies from hundred eVs up to several keV. We perform numerical simulations of the DL interaction with thermal electrons making use of the test particle approach. DL parameters assumed in the simulations are adopted from observations. We show that DLs accelerate thermal electrons parallel to the magnetic field via the electrostatic Fermi mechanism, i.e., due to reflections from DL potential humps. The electron energy gain is larger for larger DL scalar potential amplitudes and higher propagation velocities. In addition to the Fermi mechanism, electrons can be trapped by DLs in their generation region and accelerated due to transport to higher latitudes. Both mechanisms result in formation of field-aligned PADs for electrons with energies comparable to those found in observations. The Fermi mechanism provides field-aligned PADs for <1 keV electrons, while the trapping mechanism extends field-aligned PADs to higher-energy electrons. It is shown that the Fermi mechanism can result in scattering into the loss cone of up to several tenths of percent of electrons with flux peaking at energies up to several hundred eVs.

  20. Laser-produced lithium plasma as a narrow-band extended ultraviolet radiation source for photoelectron spectroscopy.

    PubMed

    Schriever, G; Mager, S; Naweed, A; Engel, A; Bergmann, K; Lebert, R

    1998-03-01

    Extended ultraviolet (EUV) emission characteristics of a laser-produced lithium plasma are determined with regard to the requirements of x-ray photoelectron spectroscopy. The main features of interest are spectral distribution, photon flux, bandwidth, source size, and emission duration. Laser-produced lithium plasmas are characterized as emitters of intense narrow-band EUV radiation. It can be estimated that the lithium Lyman-alpha line emission in combination with an ellipsoidal silicon/molybdenum multilayer mirror is a suitable EUV source for an x-ray photoelectron spectroscopy microscope with a 50-meV energy resolution and a 10-mum lateral resolution.

  1. Extending the radial diffusion model of Falthammar to non-dipole background field

    SciTech Connect

    Cunningham, Gregory Scott

    2015-05-26

    A model for radial diffusion caused by electromagnetic disturbances was published by Falthammar (1965) using a two-parameter model of the disturbance perturbing a background dipole magnetic field. Schulz and Lanzerotti (1974) extended this model by recognizing the two parameter perturbation as the leading (non--dipole) terms of the Mead Williams magnetic field model. They emphasized that the magnetic perturbation in such a model induces an electric ield that can be calculated from the motion of field lines on which the particles are ‘frozen’. Roederer and Zhang (2014) describe how the field lines on which the particles are frozen can be calculated by tracing the unperturbed field lines from the minimum-B location to the ionospheric footpoint, and then tracing the perturbed field (which shares the same ionospheric footpoint due to the frozen -in condition) from the ionospheric footpoint back to a perturbed minimum B location. The instantaneous change n Roederer L*, dL*/dt, can then be computed as the product (dL*/dphi)*(dphi/dt). dL*/Dphi is linearly dependent on the perturbation parameters (to first order) and is obtained by computing the drift across L*-labeled perturbed field lines, while dphi/dt is related to the bounce-averaged gradient-curvature drift velocity. The advantage of assuming a dipole background magnetic field, as in these previous studies, is that the instantaneous dL*/dt can be computed analytically (with some approximations), as can the DLL that results from integrating dL*/dt over time and computing the expected value of (dL*)^2. The approach can also be applied to complex background magnetic field models like T89 or TS04, on top of which the small perturbations are added, but an analytical solution is not possible and so a numerical solution must be implemented. In this talk, I discuss our progress in implementing a numerical solution to the calculation of DL*L* using arbitrary background field models with simple electromagnetic

  2. The influences of solar wind pressure and interplanetary magnetic field on global magnetic field and outer radiation belt electrons

    DOE PAGES

    Yu, J.; Li, L. Y.; Cao, J. B.; ...

    2016-07-28

    Using the Van Allen Probe in situ measured magnetic field and electron data, we examine the solar wind dynamic pressure and interplanetary magnetic field (IMF) effects on global magnetic field and outer radiation belt relativistic electrons (≥1.8 MeV). The dynamic pressure enhancements (>2 nPa) cause the dayside magnetic field increase and the nightside magnetic field reduction, whereas the large southward IMFs (Bz-IMF < –2nT) mainly lead to the decrease of the nightside magnetic field. In the dayside increased magnetic field region (magnetic local time (MLT) ~ 06:00–18:00, and L > 4), the pitch angles of relativistic electrons are mainly pancakemore » distributions with a flux peak around 90° (corresponding anisotropic index A > 0.1), and the higher-energy electrons have stronger pancake distributions (the larger A), suggesting that the compression-induced betatron accelerations enhance the dayside pancake distributions. However, in the nighttime decreased magnetic field region (MLT ~ 18:00–06:00, and L ≥ 5), the pitch angles of relativistic electrons become butterfly distributions with two flux peaks around 45° and 135° (A < 0). The spatial range of the nighttime butterfly distributions is almost independent of the relativistic electron energy, but it depends on the magnetic field day-night asymmetry and the interplanetary conditions. The dynamic pressure enhancements can make the nighttime butterfly distribution extend inward. The large southward IMFs can also lead to the azimuthal expansion of the nighttime butterfly distributions. As a result, these variations are consistent with the drift shell splitting and/or magnetopause shadowing effect.« less

  3. The influences of solar wind pressure and interplanetary magnetic field on global magnetic field and outer radiation belt electrons

    SciTech Connect

    Yu, J.; Li, L. Y.; Cao, J. B.; Reeves, Geoffrey D.; Baker, D. N.; Spence, H.

    2016-07-28

    Using the Van Allen Probe in situ measured magnetic field and electron data, we examine the solar wind dynamic pressure and interplanetary magnetic field (IMF) effects on global magnetic field and outer radiation belt relativistic electrons (≥1.8 MeV). The dynamic pressure enhancements (>2 nPa) cause the dayside magnetic field increase and the nightside magnetic field reduction, whereas the large southward IMFs (Bz-IMF < –2nT) mainly lead to the decrease of the nightside magnetic field. In the dayside increased magnetic field region (magnetic local time (MLT) ~ 06:00–18:00, and L > 4), the pitch angles of relativistic electrons are mainly pancake distributions with a flux peak around 90° (corresponding anisotropic index A > 0.1), and the higher-energy electrons have stronger pancake distributions (the larger A), suggesting that the compression-induced betatron accelerations enhance the dayside pancake distributions. However, in the nighttime decreased magnetic field region (MLT ~ 18:00–06:00, and L ≥ 5), the pitch angles of relativistic electrons become butterfly distributions with two flux peaks around 45° and 135° (A < 0). The spatial range of the nighttime butterfly distributions is almost independent of the relativistic electron energy, but it depends on the magnetic field day-night asymmetry and the interplanetary conditions. The dynamic pressure enhancements can make the nighttime butterfly distribution extend inward. The large southward IMFs can also lead to the azimuthal expansion of the nighttime butterfly distributions. As a result, these variations are consistent with the drift shell splitting and/or magnetopause shadowing effect.

  4. The influences of solar wind pressure and interplanetary magnetic field on global magnetic field and outer radiation belt electrons

    NASA Astrophysics Data System (ADS)

    Yu, J.; Li, L. Y.; Cao, J. B.; Reeves, G. D.; Baker, D. N.; Spence, H.

    2016-07-01

    Using the Van Allen Probe in situ measured magnetic field and electron data, we examine the solar wind dynamic pressure and interplanetary magnetic field (IMF) effects on global magnetic field and outer radiation belt relativistic electrons (≥1.8 MeV). The dynamic pressure enhancements (>2 nPa) cause the dayside magnetic field increase and the nightside magnetic field reduction, whereas the large southward IMFs (Bz-IMF < -2nT) mainly lead to the decrease of the nightside magnetic field. In the dayside increased magnetic field region (magnetic local time (MLT) ~ 06:00-18:00, and L > 4), the pitch angles of relativistic electrons are mainly pancake distributions with a flux peak around 90° (corresponding anisotropic index A > 0.1), and the higher-energy electrons have stronger pancake distributions (the larger A), suggesting that the compression-induced betatron accelerations enhance the dayside pancake distributions. However, in the nighttime decreased magnetic field region (MLT ~ 18:00-06:00, and L ≥ 5), the pitch angles of relativistic electrons become butterfly distributions with two flux peaks around 45° and 135° (A < 0). The spatial range of the nighttime butterfly distributions is almost independent of the relativistic electron energy, but it depends on the magnetic field day-night asymmetry and the interplanetary conditions. The dynamic pressure enhancements can make the nighttime butterfly distribution extend inward. The large southward IMFs can also lead to the azimuthal expansion of the nighttime butterfly distributions. These variations are consistent with the drift shell splitting and/or magnetopause shadowing effect.

  5. Cosmic radiation and mortality from cancer among male German airline pilots: extended cohort follow-up.

    PubMed

    Hammer, Gaël Paul; Blettner, Maria; Langner, Ingo; Zeeb, Hajo

    2012-06-01

    Commercial airline pilots are exposed to cosmic radiation and other specific occupational factors, potentially leading to increased cancer mortality. This was analysed in a cohort of 6,000 German cockpit crew members. A mortality follow-up for the years 1960-2004 was performed and occupational and dosimetry data were collected for this period. 405 deaths, including 127 cancer deaths, occurred in the cohort. The mortality from all causes and all cancers was significantly lower than in the German population. Total mortality decreased with increasing radiation doses (rate ratio (RR) per 10 mSv: 0.85, 95 % CI: 0.79, 0.93), contrasting with a non-significant increase of cancer mortality (RR per 10 mSv: 1.05, 95 % CI: 0.91, 1.20), which was restricted to the group of cancers not categorized as radiogenic in categorical analyses. While the total and cancer mortality of cockpit crew is low, a positive trend of all cancer with radiation dose is observed. Incomplete adjustment for age, other exposures correlated with duration of employment and a healthy worker survivor effect may contribute to this finding. More information is expected from a pooled analysis of updated international aircrew studies.

  6. Modulation and amplification of radiative far field heat transfer: Towards a simple radiative thermal transistor

    SciTech Connect

    Joulain, Karl; Ezzahri, Younès; Drevillon, Jérémie; Ben-Abdallah, Philippe

    2015-03-30

    We show in this article that phase change materials (PCM) exhibiting a phase transition between a dielectric state and a metallic state are good candidates to perform modulation as well as amplification of radiative thermal flux. We propose a simple situation in plane parallel geometry where a so-called radiative thermal transistor could be achieved. In this configuration, we put a PCM between two blackbodies at different temperatures. We show that the transistor effect can be achieved easily when this material has its critical temperature between the two blackbody temperatures. We also see that the more the material is reflective in the metallic state, the more switching effect is realized, whereas the more PCM transition is stiff in temperature, the more thermal amplification is high. We finally take the example of VO{sub 2} that exhibits an insulator-metallic transition at 68 °C. We show that a demonstrator of a radiative transistor could easily be achieved in view of the heat flux levels predicted. Far-field thermal radiation experiments are proposed to back the results presented.

  7. Field test of a post-closure radiation monitor

    SciTech Connect

    Reed, S.E.; Christy, C.E.; Heath, R.E.

    1995-10-01

    The DOE is conducting remedial actions at many sites contaminated with radioactive materials. After closure of these sites, long-term subsurface monitoring is typically required by law. This monitoring is generally labor intensive and expensive using conventional sampling and analysis techniques. The U.S. Department of Energy`s Morgantown Energy Technology Center (METC) has contracted with Babcock and Wilcox to develop a Long-Term Post-Closure Radiation Monitoring System (LPRMS) to reduce these monitoring costs. The system designed in Phase I of this development program monitors gamma radiation using a subsurface cesium iodide scintillator coupled to above-ground detection electronics using optical waveguide. The radiation probe can be installed to depths up to 50 meters using cone penetrometer techniques, and requires no downhole electrical power. Multiplexing, data logging and analysis are performed at a central location. A prototype LPRMS probe was built, and B&W and FERMCO field tested this monitoring probe at the Fernald Environmental Management Project in the fall of 1994 with funding from the DOE`s Office of Technology Development (EM-50) through METC. The system was used measure soil and water with known uranium contamination levels, both in drums and in situ depths up to 3 meters. For comparison purposes measurements were also performed using a more conventional survey probe with a sodium iodide scintillator directly butt-coupled to detection electronics.

  8. Novel properties of the q-analogue quantized radiation field

    NASA Technical Reports Server (NTRS)

    Nelson, Charles A.

    1993-01-01

    The 'classical limit' of the q-analog quantized radiation field is studied paralleling conventional quantum optics analyses. The q-generalizations of the phase operator of Susskind and Glogower and that of Pegg and Barnett are constructed. Both generalizations and their associated number-phase uncertainty relations are manifestly q-independent in the n greater than g number basis. However, in the q-coherent state z greater than q basis, the variance of the generic electric field, (delta(E))(sup 2) is found to be increased by a factor lambda(z) where lambda(z) greater than 1 if q not equal to 1. At large amplitudes, the amplitude itself would be quantized if the available resolution of unity for the q-analog coherent states is accepted in the formulation. These consequences are remarkable versus the conventional q = 1 limit.

  9. Quantum phenomena and the zeropoint radiation field. II

    NASA Astrophysics Data System (ADS)

    de La Peña, L.; Cetto, A. M.

    1995-04-01

    A previous paper was devoted to the discussion of a new version of stochastic electrodynamics (SED) and to the study of the conditions under which quantum mechanics can be derived from it, in the radiationless approximation. In this paper further effects on matter due to the zeropoint field are studied, such as atomic stability, radiative transitions, the Lamb shift, etc., and are shown to be correctly described by the proposed version of SED. Also, a detailed energy-balance condition and a fluctuation-dissipation relation are established; it is shown in particular that equilibrium is attained only with a field spectrum ˜Ω 3. The proposed approach is shown to suggest an understanding of quantum mechanics as a kind of limitcycle theory. Finally, a brief discussion is included about the nonchaotic behavior of the (bounded) SED system in the quantum regime, as measured by Lyapunov exponents.

  10. A simple method to quantify the coincidence between portal image graticules and radiation field centers or radiation isocenter

    SciTech Connect

    Du Weiliang; Yang, James; Luo Dershan; Martel, Mary

    2010-05-15

    Purpose: The aim of this study was to develop a computerized method to quantify the coincidence between portal image graticules and radiation field centers or radiation isocenter. Three types of graticules were included in this study: Megavoltage (MV) mechanical graticule, MV electronic portal imaging device digital graticule, and kilovoltage (kV) on-board imaging digital graticule. Methods: A metal ball bearing (BB) was imaged with MV and kV x-ray beams in a procedure similar to a Winston-Lutz test. The radiation fields, graticules, and BB were localized in eight portal images using Hough transform-based computer algorithms. The center of the BB served as a static reference point in the 3D space so that the distances between the graticule centers and the radiation field centers were calculated. The radiation isocenter was determined from the radiation field centers at different gantry angles. Results: Misalignments of MV and kV portal imaging graticules varied with the gantry or x-ray source angle as a result of mechanical imperfections of the linear accelerator and its imaging system. While the three graticules in this study were aligned to the radiation field centers and the radiation isocenter within 2.0 mm, misalignments of 1.5-2.0 mm were found at certain gantry angles. These misalignments were highly reproducible with the gantry rotation. Conclusions: A simple method was developed to quantify the alignments of portal image graticules directly against the radiation field centers or the radiation isocenter. The advantage of this method is that it does not require the BB to be placed exactly at the radiation isocenter through a precalibrated surrogating device such as room lasers or light field crosshairs. The present method is useful for radiation therapy modalities that require high-precision portal imaging such as image-guided stereotactic radiotherapy.

  11. Development of a Characterized Radiation Field for Evaluating Sensor Performance

    SciTech Connect

    Rogers, D.M.; Coggins, T.L.; Marsh, J.; Mann, St.D.; Waggoner, Ch.A.

    2008-07-01

    Numerous efforts are funded by US agencies (DOE, DoD, DHS) for development of novel radiation sensing and measurement systems. An effort has been undertaken to develop a flexible shielding system compatible with a variety of sources (beta, X-ray, gamma, and neutron) that can be highly characterized using conventional radiation detection and measurement systems. Sources available for use in this system include americium-beryllium (AmBe), plutonium-beryllium (PuBe), strontium-90 (Sr-90), californium-252 (Cf-252), krypton-85 (Kr-85), americium-241 (Am-241), and depleted uranium (DU). Shielding can be varied by utilization of materials that include lexan, water, oil, lead, and polyethylene. Arrangements and geometries of source(s) and shielding can produce symmetrical or asymmetrical radiation fields. The system has been developed to facilitate accurately repeatable configurations. Measurement positions are similarly capable of being accurately re-created. Stand-off measurement positions can be accurately re-established using differential global positioning system (GPS) navigation. Instruments used to characterize individual measurement locations include a variety of sodium iodide (NaI(Tl)) (3 x 3 inch, 4 x 4 x 16 inch, Fidler) and lithium iodide (LiI(Eu)) detectors (for use with multichannel analyzer software) and detectors for use with traditional hand held survey meters such as boron trifluoride (BF{sub 3}), helium-3 ({sup 3}He), and Geiger-Mueller (GM) tubes. Also available are Global Dosimetry thermoluminescent dosimeters (TLDs), CR39 neutron chips, and film badges. Data will be presented comparing measurement techniques with shielding/source configurations. The system is demonstrated to provide a highly functional process for comparison/characterization of various detector types relative to controllable radiation types and levels. Particular attention has been paid to use of neutron sources and measurements. (authors)

  12. Dynamics of cell and tissue growth acquired by means of extended field of view lensfree microscopy

    PubMed Central

    Momey, F.; Coutard, J.-G.; Bordy, T.; Navarro, F.; Menneteau, M.; Dinten, J.-M.; Allier, C.

    2016-01-01

    In this paper, we discuss a new methodology based on lensfree imaging to perform wound healing assay with unprecedented statistics. Our video lensfree microscopy setup is a simple device featuring only a CMOS sensor and a semi coherent illumination system. Yet it is a powerful mean for the real-time monitoring of cultivated cells. It presents several key advantages, e.g. integration into standard incubator, compatibility with standard cell culture protocol, simplicity and ease of use. It can perform the follow-up in a large field of view (25 mm2) of several crucial parameters during the culture of cells i.e. their motility, their proliferation rate or their death. Consequently the setup can gather large statistics both in space and time. Here we uses this facility in the context of wound healing assay to perform label-free measurements of the velocities of the fronts of proliferation of the cell layer as a function of time by means of particle image velocimetry (PIV) processing. However, for such tissue growth experiments, the field of view of 25 mm2 remains not sufficient and results can be biased depending on the position of the device with respect to the recipient of the cell culture. Hence, to conduct exhaustive wound healing assays, we propose to enlarge the field of view up to 10 cm2 through a raster scan, by moving the source/sensor with respect to the Petri dish. We have performed acquisitions of wound healing assay (keratinocytes HaCaT) both in real-time (25 mm2) and in final point (10 cm2) to assess the combination of velocimetry measurements and final point wide field imaging. In the future, we aim at combining directly our extended field of view acquisitions (>10 cm2) with real time ability inside the incubator. PMID:26977359

  13. Dynamics of cell and tissue growth acquired by means of extended field of view lensfree microscopy.

    PubMed

    Momey, F; Coutard, J-G; Bordy, T; Navarro, F; Menneteau, M; Dinten, J-M; Allier, C

    2016-02-01

    In this paper, we discuss a new methodology based on lensfree imaging to perform wound healing assay with unprecedented statistics. Our video lensfree microscopy setup is a simple device featuring only a CMOS sensor and a semi coherent illumination system. Yet it is a powerful mean for the real-time monitoring of cultivated cells. It presents several key advantages, e.g. integration into standard incubator, compatibility with standard cell culture protocol, simplicity and ease of use. It can perform the follow-up in a large field of view (25 mm(2)) of several crucial parameters during the culture of cells i.e. their motility, their proliferation rate or their death. Consequently the setup can gather large statistics both in space and time. Here we uses this facility in the context of wound healing assay to perform label-free measurements of the velocities of the fronts of proliferation of the cell layer as a function of time by means of particle image velocimetry (PIV) processing. However, for such tissue growth experiments, the field of view of 25 mm(2) remains not sufficient and results can be biased depending on the position of the device with respect to the recipient of the cell culture. Hence, to conduct exhaustive wound healing assays, we propose to enlarge the field of view up to 10 cm(2) through a raster scan, by moving the source/sensor with respect to the Petri dish. We have performed acquisitions of wound healing assay (keratinocytes HaCaT) both in real-time (25 mm(2)) and in final point (10 cm(2)) to assess the combination of velocimetry measurements and final point wide field imaging. In the future, we aim at combining directly our extended field of view acquisitions (>10 cm(2)) with real time ability inside the incubator.

  14. Effect of superconductivity on near-field radiative heat transfer

    NASA Astrophysics Data System (ADS)

    Králík, Tomáš; Musilová, Věra; Fořt, Tomáš; Srnka, Aleš

    2017-02-01

    Near-field (NF) radiative heat transfer (RHT) over vacuum space between bodies can exceed the far-field (FF) heat transfer by orders of magnitude. A large portion of the heat flux transferred between metals in NF is at very low frequencies, much lower than in FF. Thus a strong effect of superconductivity on NF RHT can be expected even at radiation temperatures above the superconducting critical temperature, where nearly no effect in FF is observed. We have examined experimentally the RHT between plane-parallel surfaces of niobium. Up to a fivefold decrease in NF heat flux was observed when the colder sample passed from the normal to the superconducting state. We found that a maximum decrease occurs at sample spacings ten times shorter than the spacing of crossover between the NF and FF heat flux, being ≈1000/T (μm). Applying Polder's and Van Hove's relations for NF RHT and BCS theory of superconductivity, we explain this effect and show the roles of transversal electric and magnetic modes in the steep decrease of heat flux below the critical temperature and the subsequent flux saturation at low temperatures.

  15. GLOBAL ELECTROMAGNETIC RADIATION POLLUTION: RISK ASSESSMENT FROM FIELD MEASUREMENTS AND ANIMAL EXPERIMENTS

    NASA Astrophysics Data System (ADS)

    Fragkopoulou, A. F.; Margaritis, L. H.

    2009-12-01

    The extended use of wireless technology throughout the globe in almost all developed and non-developed countries has forced a large number of scientists to get involved in the investigation of the effects. The major issue is that unlike other forms of radiation exposure, this “non-ionizing electromagnetic radiation” was not present throughout the evolution of life in earth and therefore there are no adaptive mechanisms evolved. All organisms are vulnerable to the possible effects of radiation depending on the actual exposure level. “Safety limits” on the power density have been proposed but ongoing research has shown that these limits are not really safe for humans, not mentioning the entire population of living creatures on earth. The so called “Electrosmog Pollution” originating from the numerous radio and TV stations, communication satellite emission, but most importantly from mobile phone mast antennas, are of major concern, because it is gradually increasing at exponential rate. Therefore the key question is, do living organisms react upon their exposure to fields of non ionizing electromagnetic radiation? To have this question answered extensive research is being performed in various laboratories. One approach of our research includes field measurements within houses and classrooms, since a considerable proportion of the population in each country is exposed to the radiation coming from the nearby mast stations, in order to make a risk assessment. The measurements showed that in many cases the actual radiation present was potentially harmful. In other words, although the measured values were below the national safety levels, nevertheless they were above the levels of other countries. Therefore it has been suggested that a new cellular network should be constructed in order to minimize radiation levels in living areas and schools. Our experimental work is focusing on the elucidation of the effects of non-ionizing EMFs on mice exposed to mobile

  16. Recovery of phase inconsistencies in continuously moving table extended field of view magnetic resonance imaging acquisitions.

    PubMed

    Kruger, David G; Riederer, Stephen J; Rossman, Phillip J; Mostardi, Petrice M; Madhuranthakam, Ananth J; Hu, Houchun H

    2005-09-01

    MR images formed using extended FOV continuously moving table data acquisition can have signal falloff and loss of lateral spatial resolution at localized, periodic positions along the direction of table motion. In this work we identify the origin of these artifacts and provide a means for correction. The artifacts are due to a mismatch of the phase of signals acquired from contiguous sampling fields of view and are most pronounced when the central k-space views are being sampled. Correction can be performed using the phase information from a periodically sampled central view to adjust the phase of all other views of that view cycle, making the net phase uniform across each axial plane. Results from experimental phantom and contrast-enhanced peripheral MRA studies show that the correction technique substantially eliminates the artifact for a variety of phase encode orders.

  17. Extended depth of field using a liquid crystal annular spatial light modulator.

    PubMed

    Klapp, Iftach; Solodar, Asi; Abdulhalim, Ibrahim

    2014-07-01

    A detailed investigation is presented on the tunable extended depth of field (EDOF) method, proposed recently by Klapp et al. [Opt. Lett.39, 1414 (2014)]. This method is based on temporal multiplexing of phase masks, using an annular liquid crystal spatial light modulator possessing a small number of rings. Examples of 3D simulations used to determine the phase profiles in the pupil plane are presented, as well as more detailed experimental results. Both the experimental and numerical results include comprehensive analysis of contrast dependence on both the spatial spectrum of the object and the amount of defocus. In addition, for the first time, we present the EDOF order inversion in the experimental and simulated data. The results show a profound performance of the proposed system and method.

  18. Extending the GMR current measurement range with a counteracting magnetic field.

    PubMed

    Poon, Tin Yan; Tse, Norman Chung Fai; Lau, Ricky Wing Hong

    2013-06-21

    Traditionally, current transformers are often used for current measurement in low voltage (LV) electrical networks. They have a large physical size and are not designed for use with power electronic circuits. Semiconductor-based current sensing devices such as the Hall sensor and Giant Magnetoresistive (GMR) sensor are advantageous in terms of small size, high sensitivity, wide frequency range, low power consumption, and relatively low cost. Nevertheless, the operational characteristics of these devices limit their current measurement range. In this paper, a design based on using counteracting magnetic field is introduced for extending the GMR current measurement range from 9 A (unipolar) to ±45 A. A prototype has been implemented to verify the design and the linear operation of the circuit is demonstrated by experimental results. A microcontroller unit (MCU) is used to provide an automatic scaling function to optimize the performance of the proposed current sensor.

  19. Extending the GMR Current Measurement Range with a Counteracting Magnetic Field

    PubMed Central

    Poon, Tin Yan; Tse, Norman Chung Fai; Lau, Ricky Wing Hong

    2013-01-01

    Traditionally, current transformers are often used for current measurement in low voltage (LV) electrical networks. They have a large physical size and are not designed for use with power electronic circuits. Semiconductor-based current sensing devices such as the Hall sensor and Giant Magnetoresistive (GMR) sensor are advantageous in terms of small size, high sensitivity, wide frequency range, low power consumption, and relatively low cost. Nevertheless, the operational characteristics of these devices limit their current measurement range. In this paper, a design based on using counteracting magnetic field is introduced for extending the GMR current measurement range from 9 A (unipolar) to ±45 A. A prototype has been implemented to verify the design and the linear operation of the circuit is demonstrated by experimental results. A microcontroller unit (MCU) is used to provide an automatic scaling function to optimize the performance of the proposed current sensor. PMID:23793022

  20. Avenue to understanding the mechanism of radiation effects. extended serial sacrifice experimental methodology

    SciTech Connect

    Neyman, J.

    1980-01-01

    The visualized avenue towards understanding the mechanism of the effects of radiation on the health of animals used in the experiments is, primarily, through willing interested cooperation between experimenting biologists, on the one hand, and equally willing and interested mathematical statisticians on the other. A review of the developments over two recent decades leads the author to the following conclusions relating to experimental designs; (1) the design of survival experiments with serial sacrifices as proposed by Arther C. Upton is basic, but (2) This design needs an extension. The building of this extension depends very much on the inventiveness of experimenting biologists.

  1. Characterization of a medical X-ray machine for testing the response of electronic dosimeters in pulsed radiation fields

    NASA Astrophysics Data System (ADS)

    Guimarães, Margarete C.; Da Silva, Teógenes A.

    2014-11-01

    Electronic personal dosimeters (EPD) based on solid state detectors have been used for personnel monitoring for radiation protection purpose; their use has been extended to practices with pulsed radiation beams although their performance is not well known. Deficiencies in the EPD response in pulsed radiation fields have been reported; they were not detected before since type tests and calibrations of EPDs were established in terms of continuous X and gamma reference radiations. An ISO working group was formed to elaborate a standard for test conditions and performance requirements of EPDs in pulsed beams; the PTB/Germany implemented a special X-ray facility for generating the reference pulsed radiation beams. In this work, an 800 Plus VMI medical X-ray machine of the Dosimeter Calibration Laboratory of CDTN/CNEN was characterized to verify its feasibility to perform EPD tests. Characterization of the x-ray beam was done in terms of practical peak voltage, half-value layer, mean energy and air kerma rate. Reference dosimeters used for air kerma measurements were verified as far their metrological coherence and a procedure for testing EDPs was established. Electronic personal dosimeters (EPD) have been used for personnel monitoring. EPD use has been extended to pulsed radiation beams. Deficiencies in the EPD response in pulsed beams have been reported. The feasibility of using a medical X-ray machine to perform EPD tests was studied. Reference dosimeters were verified and EPD testing procedure was established.

  2. Radiation Therapy Field Extent for Adjuvant Treatment of Axillary Metastases From Malignant Melanoma

    SciTech Connect

    Beadle, Beth M.; Guadagnolo, B. Ashleigh Ballo, Matthew T.; Lee, Jeffrey E.; Gershenwald, Jeffrey E.; Cormier, Janice N.; Mansfield, Paul F.; Ross, Merrick I.; Zagars, Gunar K.

    2009-04-01

    Purpose: To compare treatment-related outcomes and toxicity for patients with axillary lymph node metastases from malignant melanoma treated with postoperative radiation therapy (RT) to either the axilla only or both the axilla and supraclavicular fossa (extended field [EF]). Methods and Materials: The medical records of 200 consecutive patients treated with postoperative RT for axillary lymph node metastases from malignant melanoma were retrospectively reviewed. All patients received postoperative hypofractionated RT for high-risk features; 95 patients (48%) received RT to the axilla only and 105 patients (52%) to the EF. Results: At a median follow-up of 59 months, 111 patients (56%) had sustained relapse, and 99 patients (50%) had died. The 5-year overall survival, disease-free survival, and distant metastasis-free survival rates were 51%, 43%, and 46%, respectively. The 5-year axillary control rate was 88%. There was no difference in axillary control rates on the basis of the treated field (89% for axilla only vs. 86% for EF; p = 0.4). Forty-seven patients (24%) developed treatment-related complications. On both univariate and multivariate analyses, only treatment with EF irradiation was significantly associated with increased treatment-related complications. Conclusions: Adjuvant hypofractionated RT to the axilla only for metastatic malignant melanoma with high-risk features is an effective method to control axillary disease. Limiting the radiation field to the axilla only produced equivalent axillary control rates to EF and resulted in lower treatment-related complication rates.

  3. PROTON SYNCHROTRON RADIATION FROM EXTENDED JETS OF PKS 0637–752 AND 3C 273

    SciTech Connect

    Bhattacharyya, Wrijupan; Gupta, Nayantara

    2016-02-01

    Many powerful radio quasars are associated with large-scale jets, exhibiting bright knots as shown by high-resolution images from the Hubble Space Telescope (HST) and the Chandra X-ray Observatory. The radio-optical flux component from these jets can be attributed to synchrotron radiation by accelerated relativistic electrons while the IC/CMB model, by far, has been the most popular explanation for the observed X-ray emission from these jets. Recently, the IC/CMB X-ray mechanism has been strongly disfavored for 3C 273 and PKS 0637–752 since the anomalously hard and steady gamma-ray emission predicted by such models violates the observational results from Fermi-LAT. Here we propose the proton synchrotron origin of the X-ray–gamma-ray flux from the knots of PKS 0637–752 with a reasonable budget in luminosity, by considering synchrotron radiation from an accelerated proton population. Moreover, for the source 3C 273, the optical data points near 10{sup 15} Hz could not be fitted using electron synchrotron. We propose an updated proton synchrotron model, including the optical data from HST, to explain the common origin of optical-X-ray–gamma-ray emission from the knots of quasar 3C 273 as an extension of the work done by Kundu and Gupta. We also show that TeV emission from large-scale quasar jets, in principle, can arise from proton synchrotron, which we discuss in the context of knot wk8.9 of PKS 0637–752.

  4. Cosmic Ray Propagation through the Magnetic Fields of the Galaxy with Extended Halo

    NASA Technical Reports Server (NTRS)

    Zhang, Ming

    2005-01-01

    In this project we perform theoretical studies of 3-dimensional cosmic ray propagation in magnetic field configurations of the Galaxy with an extended halo. We employ our newly developed Markov stochastic process methods to solve the diffusive cosmic ray transport equation. We seek to understand observations of cosmic ray spectra, composition under the constraints of the observations of diffuse gamma ray and radio emission from the Galaxy. The model parameters are directly are related to properties of our Galaxy, such as the size of the Galactic halo, particle transport in Galactic magnetic fields, distribution of interstellar gas, primary cosmic ray source distribution and their confinement in the Galaxy. The core of this investigation is the development of software for cosmic ray propagation models with the Markov stochastic process approach. Values of important model parameters for the halo diffusion model are examined in comparison with observations of cosmic ray spectra, composition and the diffuse gamma-ray background. This report summarizes our achievement in the grant period at the Florida Institute of Technology. Work at the co-investigator's institution, the University of New Hampshire, under a companion grant, will be covered in detail by a separate report.

  5. An extended cost potential field cellular automata model considering behavior variation of pedestrian flow

    NASA Astrophysics Data System (ADS)

    Guo, Fang; Li, Xingli; Kuang, Hua; Bai, Yang; Zhou, Huaguo

    2016-11-01

    The original cost potential field cellular automata describing normal pedestrian evacuation is extended to study more general evacuation scenarios. Based on the cost potential field function, through considering the psychological characteristics of crowd under emergencies, the quantitative formula of behavior variation is introduced to reflect behavioral changes caused by psychology tension. The numerical simulations are performed to investigate the effects of the magnitude of behavior variation, the different pedestrian proportions with different behavior variation and other factors on the evacuation efficiency and process in a room. The spatiotemporal dynamic characteristic during the evacuation process is also discussed. The results show that compared with the normal evacuation, the behavior variation under an emergency does not necessarily lead to the decrease of the evacuation efficiency. At low density, the increase of the behavior variation can improve the evacuation efficiency, while at high density, the evacuation efficiency drops significantly with the increasing amplitude of the behavior variation. In addition, the larger proportion of pedestrian affected by the behavior variation will prolong the evacuation time.

  6. Portable low-coherence interferometry for quantitatively imaging fast dynamics with extended field of view

    NASA Astrophysics Data System (ADS)

    Shaked, Natan T.; Girshovitz, Pinhas; Frenklach, Irena

    2014-06-01

    We present our recent advances in the development of compact, highly portable and inexpensive wide-field interferometric modules. By a smart design of the interferometric system, including the usage of low-coherence illumination sources and common-path off-axis geometry of the interferometers, spatial and temporal noise levels of the resulting quantitative thickness profile can be sub-nanometric, while processing the phase profile in real time. In addition, due to novel experimentally-implemented multiplexing methods, we can capture low-coherence off-axis interferograms with significantly extended field of view and in faster acquisition rates. Using these techniques, we quantitatively imaged rapid dynamics of live biological cells including sperm cells and unicellular microorganisms. Then, we demonstrated dynamic profiling during lithography processes of microscopic elements, with thicknesses that may vary from several nanometers to hundreds of microns. Finally, we present new algorithms for fast reconstruction (including digital phase unwrapping) of off-axis interferograms, which allow real-time processing in more than video rate on regular single-core computers.

  7. Deep Medium-Band Subaru Imaging of the MUSYC Extended Chandra Deep Field South

    NASA Astrophysics Data System (ADS)

    Urry, C. Megan; Cardamone, C.; van Dokkum, P.; Gawiser, E.; Brammer, G.; Taylor, N.; Treister, E.; Taniguchi, Y.; Sasaki, S.; Virani, S.; Kriek, M.

    2009-01-01

    We report on deep medium-band imaging with the Subaru telescope, in 18 filters from 427 nm to 856 nm, of the MUSYC survey field in the Extended Chandra Deep Field South. We detect 80,000 galaxies to equivalent magnitude R 27 mag, of which approximately 1,000 are X-ray-luminous AGN observed with Chandra and XMM. Combining the Subaru data with optical and IR data (in U,U38,B,V,R,I,z,J,K) we obtain photometric redshifts using EAZY, a fast public photometric redshift code, in the range 0

  8. Field Comparisons of Direct and Component Measurements of Net Radiation under Clear Skies.

    NASA Astrophysics Data System (ADS)

    Duchon, Claude E.; Wilk, Gregory E.

    1994-02-01

    applied to simultaneous measurements from the net pyrradiometer, pyranometer, pyrgeometer, and the inner cup temperature, assumed to he at air temperature, to estimate the individual components. Although a substantial difference in shartwave sensitivity was computed using this method, the result was not definitive because of the limited number and the narrow range of longwave observations. Nevertheless, the method can be employed in the field to verify uniform sensitivity of a net pyrradiometer's sensing surfaces to shortwave and longwave radiation. The method may have particular application to Fritschen-type net pyrradiometers of recently improved design after extended field use.

  9. Trapped-Ion Quantum Logic with Global Radiation Fields

    NASA Astrophysics Data System (ADS)

    Weidt, S.; Randall, J.; Webster, S. C.; Lake, K.; Webb, A. E.; Cohen, I.; Navickas, T.; Lekitsch, B.; Retzker, A.; Hensinger, W. K.

    2016-11-01

    Trapped ions are a promising tool for building a large-scale quantum computer. However, the number of required radiation fields for the realization of quantum gates in any proposed ion-based architecture scales with the number of ions within the quantum computer, posing a major obstacle when imagining a device with millions of ions. Here, we present a fundamentally different approach for trapped-ion quantum computing where this detrimental scaling vanishes. The method is based on individually controlled voltages applied to each logic gate location to facilitate the actual gate operation analogous to a traditional transistor architecture within a classical computer processor. To demonstrate the key principle of this approach we implement a versatile quantum gate method based on long-wavelength radiation and use this method to generate a maximally entangled state of two quantum engineered clock qubits with fidelity 0.985(12). This quantum gate also constitutes a simple-to-implement tool for quantum metrology, sensing, and simulation.

  10. Trapped-Ion Quantum Logic with Global Radiation Fields.

    PubMed

    Weidt, S; Randall, J; Webster, S C; Lake, K; Webb, A E; Cohen, I; Navickas, T; Lekitsch, B; Retzker, A; Hensinger, W K

    2016-11-25

    Trapped ions are a promising tool for building a large-scale quantum computer. However, the number of required radiation fields for the realization of quantum gates in any proposed ion-based architecture scales with the number of ions within the quantum computer, posing a major obstacle when imagining a device with millions of ions. Here, we present a fundamentally different approach for trapped-ion quantum computing where this detrimental scaling vanishes. The method is based on individually controlled voltages applied to each logic gate location to facilitate the actual gate operation analogous to a traditional transistor architecture within a classical computer processor. To demonstrate the key principle of this approach we implement a versatile quantum gate method based on long-wavelength radiation and use this method to generate a maximally entangled state of two quantum engineered clock qubits with fidelity 0.985(12). This quantum gate also constitutes a simple-to-implement tool for quantum metrology, sensing, and simulation.

  11. High-resolution optical telescope for ultraviolet /UV/ radiation field

    NASA Technical Reports Server (NTRS)

    Karayan, W. W.

    1979-01-01

    Design techniques are discussed for all-reflecting optics from first-order system considerations and applications currently utilized in the field of astronomical optics. The solution of the Dall-Karkham design problem is described, showing the advantage of inexpensive construction as compared with higher order surfaces. The design process reported here is a F/5 collecting system which quickly mates directly with the spectrometer; it is capable of achieving desired high resolution and sensitivity requirements. The theoretical limit of aberration tolerances is achieved with less than 1/8 of a wavelength at final focus (OPD). The design of spectrometer for ultra-violet (UV) radiation and its mechanism is included in this study.

  12. Observations of the diffuse near-UV radiation field

    NASA Technical Reports Server (NTRS)

    Murthy, J.; Henry, R. C.; Feldman, P. D.; Tennyson, P. D.

    1990-01-01

    The diffuse radiation field from 1650-3100 A has been observed by spectrometer aboard the Space Shuttle, and the contributions of the zodiacal light an the diffuse cosmic background to the signal have been derived. Colors ranging from 0.65 to 1.2 are found for the zodiacal light with an almost linear increase in the color with ecliptic latitude. This rise in color is due to UV brightness remaining almost constant while the visible brightnesses drop by almost a factor of two. This is interpreted as evidence that the grains responsible for the UV scattering have much more uniform distribution with distance from the ecliptic plane than do those grains responsible for the visible scattering. Intensities for the cosmic diffuse background ranging from 300 units to 900 units are found which are not consistent with either a correlation with N(H I) or with spatial isotropy.

  13. Gravity Fields of the Moon Derived from GRAIL Primary and Extended Mission Data (Invited)

    NASA Astrophysics Data System (ADS)

    Lemoine, F. G.; Goossens, S. J.; Sabaka, T. J.; Nicholas, J. B.; Mazarico, E.; Rowlands, D. D.; Loomis, B.; Chinn, D. S.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.

    2013-12-01

    The Gravity Recovery and Interior Laboratory (GRAIL) spacecraft conducted the mapping of the gravity field of the Moon from March 1, 2012 to May 29, 2012, for the primary mission and from August 30, 2012 to December 14, 2012 for the extended mission and endgame. During both mission phases, the twin spacecraft acquired highly precise Ka-band range-rate (KBRR) intersatellite ranging data and Deep Space Network (DSN) data from altitudes of 2.3 to 98.2 km above the lunar surface. We have processed the GRAIL data using the NASA GSFC GEODYN orbit determination and geodetic parameter estimation program and used the supercomputers of the NASA Center for Climate Simulation (NCCS) at NASA GSFC to accumulate the SRIF arrays and derive the geopotential solutions. During the extended mission, the spacecraft orbits were maintained at a mean altitude of ~23 km, compared to ~50 km during the primary mission. In addition, from December 7 to December 14, 2012, data were acquired from a mean altitude of 11.5 km. With these data, we have derived solutions in spherical harmonics to degree 900. The new gravity solutions show improved correlations with LOLA-derived topography to very high degree and order and resolve many lunar features in the geopotential with a resolution of less than 15 km. We discuss the methods we used for the processing of the GRAIL data, and evaluate these solutions with respect to the derived power spectra, Bouguer anomalies, and fits with independent data (such as from the low-altitude phase of the Lunar Prospector mission).

  14. Comptonization in Ultra-Strong Magnetic Fields: Numerical Solution to the Radiative Transfer Problem

    NASA Technical Reports Server (NTRS)

    Ceccobello, C.; Farinelli, R.; Titarchuk, L.

    2014-01-01

    We consider the radiative transfer problem in a plane-parallel slab of thermal electrons in the presence of an ultra-strong magnetic field (B approximately greater than B(sub c) approx. = 4.4 x 10(exp 13) G). Under these conditions, the magnetic field behaves like a birefringent medium for the propagating photons, and the electromagnetic radiation is split into two polarization modes, ordinary and extraordinary, that have different cross-sections. When the optical depth of the slab is large, the ordinary-mode photons are strongly Comptonized and the photon field is dominated by an isotropic component. Aims. The radiative transfer problem in strong magnetic fields presents many mathematical issues and analytical or numerical solutions can be obtained only under some given approximations. We investigate this problem both from the analytical and numerical point of view, provide a test of the previous analytical estimates, and extend these results with numerical techniques. Methods. We consider here the case of low temperature black-body photons propagating in a sub-relativistic temperature plasma, which allows us to deal with a semi-Fokker-Planck approximation of the radiative transfer equation. The problem can then be treated with the variable separation method, and we use a numerical technique to find solutions to the eigenvalue problem in the case of a singular kernel of the space operator. The singularity of the space kernel is the result of the strong angular dependence of the electron cross-section in the presence of a strong magnetic field. Results. We provide the numerical solution obtained for eigenvalues and eigenfunctions of the space operator, and the emerging Comptonization spectrum of the ordinary-mode photons for any eigenvalue of the space equation and for energies significantly lesser than the cyclotron energy, which is on the order of MeV for the intensity of the magnetic field here considered. Conclusions. We derived the specific intensity of the

  15. 3D Extended Logging for Geothermal Resources: Field Trials with the Geo-Bilt System

    SciTech Connect

    Mallan, R; Wilt, M; Kirkendall, B; Kasameyer, P

    2002-05-29

    Geo-BILT (Geothermal Borehole Induction Logging Tool) is an extended induction logging tool designed for 3D resistivity imaging around a single borehole. The tool was developed for deployment in high temperature geothermal wells under a joint program funded by the California Energy Commission, Electromagnetic Instruments (EMI) and the U.S. Department of Energy. EM1 was responsible for tool design and manufacture, and numerical modeling efforts were being addressed at Lawrence Livermore Laboratory (LLNL) and other contractors. The field deployment was done by EM1 and LLNL. The tool operates at frequencies from 2 to 42 kHz, and its design features a series of three-component magnetic sensors offset at 2 and 5 meters from a three-component magnetic source. The combined package makes it possible to do 3D resistivity imaging, deep into the formation, from a single well. The manufacture and testing of the tool was completed in spring of 2001, and the initial deployment of Geo-BILT occurred in May 2001 at the Lost Hills oil field in southern California at leases operated by Chevron USA. This site was chosen for the initial field test because of the favorable geological conditions and the availability of a number of wells suitable for tool deployment. The second deployment occurred in April 2002 at the Dixie Valley geothermal field, operated by Caithness Power LLC, in central Nevada. This constituted the first test in a high temperature environment. The Chevron site features a fiberglass-cased observation well in the vicinity of a water injector. The injected water, which is used for pressure maintenance and for secondary sweep of the heavy oil formation, has a much lower resistivity than the oil bearing formation. This, in addition to the non-uniform flow of this water, creates a 3D resistivity structure, which is analogous to conditions produced from flowing fractures adjacent to geothermal boreholes. Therefore, it is an excellent site for testing the 3D capability of

  16. Optimized non-integer order phase mask to extend the depth of field of an imaging system

    NASA Astrophysics Data System (ADS)

    Liu, Jiang; Miao, Erlong; Sui, Yongxin; Yang, Huaijiang

    2016-09-01

    Wavefront coding is an effective optical technique used to extend the depth of field for an incoherent imaging system. Through introducing an optimized phase mask to the pupil plane, the modulated optical transfer function is defocus-invariant. In this paper, we proposed a new form phase mask using non-integer order and signum function to extend the depth of field. The performance of the phase mask is evaluated by comparing defocused modulation transfer function invariant and Fisher information with other phase masks. Defocused imaging simulation is also carried out. The results demonstrate the advantages of non-integer order phase mask and its effectiveness on the depth of field extension.

  17. Treatment of stage i and ii mediastinal Hodgkin disease: a comparison of involved fields, extended fields, and involved fields followed by MOPP in patients stage by laparotomy

    SciTech Connect

    Hagemeister, F.B.; Fuller, L.M.; Sullivan, J.A.; North, L.; Velasquez, W.; Conrad, F.G.; McLaughlin, P.; Butter, J.J.; Shullenberger, C.C.

    1981-12-01

    Three treatment programs for Stage I and II mediastinal Hodgkin disease (established by laparotomy) were compared. Involved-field radiotherapy + MOPP gave a disease-free survival rate of 97%, significantly different from 62% and 55% for involved and extended fields, respectively. Corresponding survival figures of 97%, 88%, and 84% were not signiticantly different statistically due to salvage with radiotherapy and/or chemotherapy. Among patients given radiotherapy alone, the survival figure of 94% for limited mediastinal disease was significantly better than 63% for extensive mediastinal and hilar disease; corresponding disease-free figures of 72% and 35% were also significantly different. Constitutional symptoms were an important prognostic factor in disease-free survival following the use of involved fields; hilar disease was important only with large mediastinal masses. Most relapses were intrathoracic; MOPP alone salvaged only 47%. Treatment of State I and II Hodgkin disease should be based on symptoms, extent of mediastinal disease, and hilar involvement.

  18. A modular, extendible and field-tolerant multichannel vector magnetometer based on current sensor SQUIDs

    NASA Astrophysics Data System (ADS)

    Storm, J.-H.; Drung, D.; Burghoff, M.; Körber, R.

    2016-09-01

    We present the prototype module of our extendible and robust multichannel SQUID magnetometer system. A large multi-module arrangement can be implemented by using up to 7 modules. The system is intended for high-precision measurements of biomagnetism and spin precession. Further demanding applications are magnetorelaxometry and ultra-low-field nuclear magnetic resonance (ULF NMR), where pulsed magnetic fields of up to 100 mT are typically applied. The system is operated inside the Berlin magnetically shielded room (BMSR-2) and equipped with 18 magnetometers consisting of niobium (Nb) wire-wound pick-up coils. A total of 16 small pick-up coils with 17.1 mm diameter form a regular grid with individual channels arranged to ensure system sensitivity covers all three orthogonal spatial directions. Two large hexagonal pick-up coils with an equivalent diameter of 74.5 mm sensitive in z-direction surround the grid at two different heights and are suitable for the detection of deep sources. Each pick-up coil is connected to the input of a thin-film Nb SQUID current sensor via a detachable superconducting contact. The SQUIDs are equipped with integrated input current limiters. Feedback into the pick-up coils is employed to minimise crosstalk between channels. The current sensor chip package includes a superconducting shield of Nb. The field distortion of the prototype and a multi-module arrangement was analysed by numerical simulation. The measured noise of the small magnetometers was between 0.6 and 1.5 fT {{Hz}}-1/2, and well below 1 fT {{Hz}}-1/2 for the large ones. Using a software gradiometer, we achieved a minimum noise level of 0.54 fT {{Hz}}-1/2. We performed ULF NMR experiments, verifying the system’s robustness against pulsed fields, and magnetoencephalographgy (MEG) on somatosensory evoked neuronal activity. The low noise performance of our 18-channel prototype enabled the detection of high-frequency components at around 1 kHz by MEG.

  19. A Systematic Global Mapping of the Radiation Field at Aviation Altitudes

    NASA Technical Reports Server (NTRS)

    Stassinopoulos, E. G.; Stauffer, C. A.; Brucker, G. J.

    2003-01-01

    This paper presents early results from aircraft measurements made by a Low-LET Radiation Spectrometer (LoLRS), as part of a long-range effort to study the complex dynamics of the atmospheric radiation field. For this purpose, a comprehensive data base is being generated to enable a multivariable global mapping (and eventually modeling) of doses and Linear-Energy-Transfer (LET) spectra at aviation altitudes. To accomplish this, a methodical collection of data from the LoLRS (and other instruments), is planned over extended periods of time, in a manner that complements some previous isolated and sporadic measurements by other workers, with the objective to generate a detailed long-range description of the cosmic-ray induced particle environment and to study its variability and dependence on atmospheric thickness, magnetic latitude, L-shell or rigidity, space weather, solar particle events, solar cycle effects, magnetic field variation, diurnal and seasonal effects, and atmospheric weather. Analysis of initial data indicates that the dose is rising with increasing altitude and increasing magnetic latitude. Comparison of total doses with predictions is in good agreement.

  20. Weiss mean-field approximation for multicomponent stochastic spatially extended systems.

    PubMed

    Kurushina, Svetlana E; Maximov, Valerii V; Romanovskii, Yurii M

    2014-08-01

    We develop a mean-field approach for multicomponent stochastic spatially extended systems and use it to obtain a multivariate nonlinear self-consistent Fokker-Planck equation defining the probability density of the state of the system, which describes a well-known model of autocatalytic chemical reaction (brusselator) with spatially correlated multiplicative noise, and to study the evolution of probability density and statistical characteristics of the system in the process of spatial pattern formation. We propose the finite-difference method for the numerical solving of a general class of multivariate nonlinear self-consistent time-dependent Fokker-Planck equations. We illustrate the accuracy and reliability of the method by applying it to an exactly solvable nonlinear Fokker-Planck equation (NFPE) for the Shimizu-Yamada model [Prog. Theor. Phys. 47, 350 (1972)] and nonlinear Fokker-Planck equation [Desai and Zwanzig, J. Stat. Phys. 19, 1 (1978)] obtained for a nonlinear stochastic mean-field model introduced by Kometani and Shimizu [J. Stat. Phys. 13, 473 (1975)]. Taking the problems indicated above as an example, the accuracy of the method is compared with the accuracy of Hermite distributed approximating functional method [Zhang et al., Phys. Rev. E 56, 1197 (1997)]. Numerical study of the NFPE solutions for a stochastic brusselator shows that in the region of Turing bifurcation several types of solutions exist if noise intensity increases: unimodal solution, transient bimodality, and an interesting solution which involves multiple "repumping" of probability density through bimodality. Additionally, we study the behavior of the order parameter of the system under consideration and show that the second type of solution arises in the supercritical region if noise intensity values are close to the values appropriate for the transition from bimodal stationary probability density for the order parameter to the unimodal one.

  1. Transport in stellar radiation zones with magnetic field

    NASA Astrophysics Data System (ADS)

    Mathis, S.; Zahn, J.-P.

    We examine the interaction between meridian circulation and turbulence in rotating stars with an axisymetric magnetic field. In the same way as Zahn (1992) and Spiegel and Zahn (1992), the turbulence is assumed to be anisotropic, due to the stratification, with stronger transport in the horizontal directions than in the vertical. We keep the 'shellular rotation' hypothesis, but we expand the differential rotation in latitude to higher order, which allow us to treat simultaneously the radiative interior and the tachocline(s). We derive the partial differential equations which govern the transport of magnetic field, temperature, angular momentum and chemical elements with taking into account the non-stationarity of the problem, the mu-gradients, the effect of horizontal turbulence in thermal imbalance and a general equation of state like in Maeder and Zahn (1998). Finally, we apply the beta-viscosity prescription which has been derived from Couette-Taylor experiments (Richard and Zahn (1999)) to the problem of transport in stellar interiors to obtain a new expression for the horizontal component of the turbulent viscosity, nuh, and its companion the horizontal diffusivity, Dh. The next step will be to implement these new equations in existing stellar structure codes, to model the evolution of rotating stars.

  2. Wireless Links in the Radiative Near Field via Bessel Beams

    NASA Astrophysics Data System (ADS)

    Heebl, Jason D.; Ettorre, Mauro; Grbic, Anthony

    2016-09-01

    The generation of propagating Bessel beams is typically limited to optical frequencies with bulky experimental setups. Recent works have demonstrated Bessel-beam generation at microwave and millimeter-wave frequencies utilizing low-profile, planar, leaky-wave antennas. These studies have assumed a single leaky mode in the antenna. In this work, the rigorous analysis of a planar Bessel-beam launcher supporting multiple modes is presented. By employing the mode-matching technique, a complete electromagnetic solution of the structure, its supported modes, and radiated fields is obtained. Additionally, a coupled system of two planar Bessel launchers is analyzed, and it is shown that the system can both transmit and receive Bessel beams. The energy-transfer characteristics of the coupled system are analyzed and discussed. An analysis of the coupled system's even and odd modes of operation show that efficient power transfer is possible, and that an odd mode is preferred since it yields higher field confinement and power-transfer efficiency.

  3. Extractable proteins from field radiation vulcanized natural rubber latex

    NASA Astrophysics Data System (ADS)

    Parra, Duclerc F.; Pinto Martins, Carlos Felipe; Collantes, Chirinos H. D.; Lugao, Ademar B.

    2005-07-01

    The type I allergy associated with the use of natural rubber latex (NRL) products is caused by the NRL proteins leached by the sweat or other body fluids. Makuuchi's group proposed for the first time the proteins removal by the addition of water-soluble polymers (WSP) on radiation vulcanization of natural rubber latex (RVNRL) that is a promising process under development in many countries. In this study, Brazilian field natural rubber was irradiated with a 60Co gamma source to reduce the content of WSP in the final product. WSP was used as additive to improve the extraction of protein. After irradiation the RVNRL was centrifuged to extract the WSP and proteins. The analytical methodology for protein content was based on the modified Lowry method according to ASTM D5712. Protein determination was carried out in serum of latex and in the extracts of the gloves. The concentration of extractable water-soluble proteins in serum of irradiated field NRL (NRL1), not irradiated one (NRL2); of twice centrifuged sample with polymer additive NRL (NRL3) and of the glove manufactured (NRLG) are compared with commercial glove (CG). The irradiation process increases the extractable water-soluble proteins, EP, as reported in the literature. In this study the use of polymeric additive on the bi-centrifugation process to remove protein was successful and the EP of the glove obtained in NRL3 was at around 40% of the commercial glove.

  4. The wave properties of matter and the zeropoint radiation field

    NASA Astrophysics Data System (ADS)

    de La Peña, L.; Cetto, A. M.

    1994-05-01

    The origin of the wave properties of matter is discussed from the point of view of stochastic electrodynamics. A nonrelativistic model of a charged particle with an effective structure embedded in the random zeropoint radiation field reveals that the field induces a high-frequency vibration on the particle; internal consistency of the theory fixes the frequency of this jittering at mc2/ħ. The particle is therefore assumed to interact intensely with stationary zeropoint waves of this frequency as seen from its proper frame of reference; such waves, identified here as de Broglie's phase waves, give rise to a modulated wave in the laboratory frame, with de Broglie's wavelength and phase velocity equal to the particle velocity. The time-independent equation that describes this modulated wave is shown to be the stationary Schrödinger equation (or the Klein-Gordon equation in the relativistic version). In a heuristic analysis appled to simple periodic cases, the quantization rules are recovered from the assumption that for a particle in a stationary state there must correspond a stationary modulation. Along an independent and complementary line of reasoning, an equation for the probability amplitude in configuration space for a particle under a general potential V(x) is constructed, and it is shown that under conditions derived from stochastic electrodynamics it reduces to Schrödinger's equation. This equation reflects therefore the dual nature of the quantum particles, by describing simultaneously the corresponding modulated wave and the ensemble of particles.

  5. Ultrahigh resolution optical coherence elastography using a Bessel beam for extended depth of field

    NASA Astrophysics Data System (ADS)

    Curatolo, Andrea; Villiger, Martin; Lorenser, Dirk; Wijesinghe, Philip; Fritz, Alexander; Kennedy, Brendan F.; Sampson, David D.

    2016-03-01

    Visualizing stiffness within the local tissue environment at the cellular and sub-cellular level promises to provide insight into the genesis and progression of disease. In this paper, we propose ultrahigh-resolution optical coherence elastography, and demonstrate three-dimensional imaging of local axial strain of tissues undergoing compressive loading. The technique employs a dual-arm extended focus optical coherence microscope to measure tissue displacement under compression. The system uses a broad bandwidth supercontinuum source for ultrahigh axial resolution, Bessel beam illumination and Gaussian beam detection, maintaining sub-2 μm transverse resolution over nearly 100 μm depth of field, and spectral-domain detection allowing high displacement sensitivity. The system produces strain elastograms with a record resolution (x,y,z) of 2×2×15 μm. We benchmark the advances in terms of resolution and strain sensitivity by imaging a suitable inclusion phantom. We also demonstrate this performance on freshly excised mouse aorta and reveal the mechanical heterogeneity of vascular smooth muscle cells and elastin sheets, otherwise unresolved in a typical, lower resolution optical coherence elastography system.

  6. Nonrotating and rotating neutron stars in the extended field theoretical model

    SciTech Connect

    Dhiman, Shashi K.; Kumar, Raj; Agrawal, B. K.

    2007-10-15

    We study the properties of nonrotating and rotating neutron stars for a new set of equations of state (EOSs) with different high-density behavior obtained using the extended field theoretical model. The high-density behavior for these EOSs are varied by varying the {omega}-meson self-coupling and hyperon-meson couplings in such a way that the quality of fit to the bulk nuclear observables, nuclear matter incompressibility coefficient, and hyperon-nucleon potential depths remain practically unaffected. We find that the largest value for maximum mass for the nonrotating neutron star is 2.1M{sub {center_dot}}. The radius for a neutron star with canonical mass is 12.8-14.1 km, provided only those EOSs are considered for which the maximum mass is larger than 1.6M{sub {center_dot}}, the lower bound on the maximum mass measured so far. Our results for the very recently discovered fastest rotating neutron star indicate that this star is supramassive with mass 1.7M{sub {center_dot}}-2.7M{sub {center_dot}} and circumferential equatorial radius 12-19 km.

  7. Duality principle from rarefied to dense gas and extended thermodynamics with six fields

    NASA Astrophysics Data System (ADS)

    Arima, Takashi; Ruggeri, Tommaso; Sugiyama, Masaru

    2017-01-01

    We present an extended thermodynamics (ET) theory of dissipative dense gases. In particular, we study the ET theory with six fields, where we neglect shear viscosity and heat conductivity. We postulate a simple principle of duality between rarefied and dense gases. This principle is based on the microscopic analysis of the energy exchange between different modes of the molecular motion. The basic system of equations satisfies all principles of ET, that is, Galilean invariance, entropy principle, and thermodynamic stability (entropy convexity), and, as in the ET theory of rarefied gases, the constitutive equations are completely determined by the thermal and caloric equations of state. The system is simplest after the Euler system, but, in contrast to the Euler system, we may have a global smooth solution due to the fact that the system is dissipative symmetric hyperbolic and satisfies the so-called K condition. There emerge two nonequilibrium temperatures; one is due to the translational modes, and the other is due to the internal modes such as rotation and vibration of a molecule. This viewpoint allows us to understand the origin of the dynamic pressure in a more clear way. Furthermore we evaluate the characteristic velocities associated with the hyperbolic system and address the fluctuation-dissipation relation of the bulk viscosity. As a typical example, we analyze van der Waals fluids based on the present theory.

  8. Optics optimization in high-resolution imaging module with extended depth of field

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Bakin, Dmitry; Liu, Changmeng; George, Nicholas

    2008-08-01

    The standard imaging lens for a high resolution sensor was modified to achieve the extended depth of field (EDoF) from 300 mm to infinity. In the module the raw sensor outputs are digitally processed to obtain high contrast images. The overall module is considered as an integrated computational imaging system (ICIS). The simulation results for illustrative designs with different amount of spherical aberrations are provided and compared. Based on the results of simulations we introduced the limiting value of the PSF Strehl ratio as the integral threshold criteria to be used during EDoF lens optimization. A four-element standard lens was modified within the design constraints to achieve the EDoF performance. Two EDoF designs created with different design methods are presented. The imaging modules were compared in terms of Strehl ratios, limiting resolution, modulation frequencies at 50% contrast, and SNR. The output images were simulated for EDoF modules, passed through the image processing pipeline, and compared against the images obtained with the standard lens module.

  9. Recommendations for Improving Consistency in the Radiation Fields Used During Testing of Radiation Detection Instruments for Homeland Security Applications

    PubMed Central

    Pibida, L; Mille, M; Norman, B

    2013-01-01

    Several measurements and calculations were performed to illustrate the differences that can be observed in the determination of exposure rate or ambient dose equivalent rate used for testing radiation detection systems against consensus standards. The large variations observed support our recommendation that better consistency in the test radiation fields can be achieved by specifying the source activity and testing distance instead of the field strength. PMID:26401434

  10. Out-of-Field Cell Survival Following Exposure to Intensity-Modulated Radiation Fields

    SciTech Connect

    Butterworth, Karl T.; McGarry, Conor K.; Trainor, Colman; O'Sullivan, Joe M.; Hounsell, Alan R.; Prise, Kevin M.

    2011-04-01

    Purpose: To determine the in-field and out-of-field cell survival of cells irradiated with either primary field or scattered radiation in the presence and absence of intercellular communication. Methods and Materials: Cell survival was determined by clonogenic assay in human prostate cancer (DU145) and primary fibroblast (AGO1552) cells following exposure to different field configurations delivered using a 6-MV photon beam produced with a Varian linear accelerator. Results: Nonuniform dose distributions were delivered using a multileaf collimator (MLC) in which half of the cell population was shielded. Clonogenic survival in the shielded region was significantly lower than that predicted from the linear quadratic model. In both cell lines, the out-of-field responses appeared to saturate at 40%-50% survival at a scattered dose of 0.70 Gy in DU-145 cells and 0.24 Gy in AGO1522 cells. There was an approximately eightfold difference in the initial slopes of the out-of-field response compared with the {alpha}-component of the uniform field response. In contrast, cells in the exposed part of the field showed increased survival. These observations were abrogated by direct physical inhibition of cellular communication and by the addition of the inducible nitric oxide synthase inhibitor aminoguanidine known to inhibit intercellular bystander effects. Additional studies showed the proportion of cells irradiated and dose delivered to the shielded and exposed regions of the field to impact on response. Conclusions: These data demonstrate out-of-field effects as important determinants of cell survival following exposure to modulated irradiation fields with cellular communication between differentially irradiated cell populations playing an important role. Validation of these observations in additional cell models may facilitate the refinement of existing radiobiological models and the observations considered important determinants of cell survival.

  11. Patterns of Failure and Treatment-Related Toxicity in Advanced Cervical Cancer Patients Treated Using Extended Field Radiotherapy With Curative Intent

    SciTech Connect

    Rajasooriyar, Chrishanthi; Van Dyk, Sylvia; Bernshaw, David; Kondalsamy-Chennakesavan, Srinivas; Barkati, Maroie; Narayan, Kailash

    2011-06-01

    Purpose: The purpose of this study was to evaluate the patterns of failure and overall survival (OS) and disease-free survival (DFS) rates in cervical cancer patients who had metastatic disease in common iliac or para-aortic lymph nodes and were treated with curative intent, using extended field radiotherapy (EFRT). Methods and Materials: This was a retrospective study involving 39 patients treated from January 1996 to June 2007, using EFRT with concurrent chemotherapy and intracavitary brachytherapy. EFRT consisted of 45 Gy in 1.8-Gy fractions. Radiation to involved nodes was boosted to a total dose of 50.4 to 54 Gy. Primary tumor radiation was boosted to a dose of 80 Gy using brachytherapy. Results: Overall, 30 patients (77%) have relapsed. The 5-year OS rate was 26% (95% confidence interval [CI], 11-44). The 5-year DFS rate was 19.4% (95% CI, 8-35). Only 3 patients (7.5%) experienced treatment failure exclusively within the treatment field, and 2 patients underwent salvage treatment. Grade 3 to 4 acute bone marrow and gastrointestinal toxicities were observed in 10 (26%) and 7 (18%) patients, respectively. Conclusions: Concurrent chemotherapy and EFRT treatment was well tolerated. Most patients showed failure at multiple sites and outside the treatment field. Only 3/39 patients had failures exclusively within the treatment field, and 2 underwent salvage treatment.

  12. Physiologically gated microbeam radiation using a field emission x-ray source array

    SciTech Connect

    Chtcheprov, Pavel E-mail: zhou@email.unc.edu; Burk, Laurel; Inscoe, Christina; Ger, Rachel; Hadsell, Michael; Lu, Jianping; Yuan, Hong; Zhang, Lei; Chang, Sha; Zhou, Otto E-mail: zhou@email.unc.edu

    2014-08-15

    Purpose: Microbeam radiation therapy (MRT) uses narrow planes of high dose radiation beams to treat cancerous tumors. This experimental therapy method based on synchrotron radiation has been shown to spare normal tissue at up to 1000 Gy of peak entrance dose while still being effective in tumor eradication and extending the lifetime of tumor-bearing small animal models. Motion during treatment can lead to significant movement of microbeam positions resulting in broader beam width and lower peak to valley dose ratio (PVDR), which reduces the effectiveness of MRT. Recently, the authors have demonstrated the feasibility of generating microbeam radiation for small animal treatment using a carbon nanotube (CNT) x-ray source array. The purpose of this study is to incorporate physiological gating to the CNT microbeam irradiator to minimize motion-induced microbeam blurring. Methods: The CNT field emission x-ray source array with a narrow line focal track was operated at 160 kVp. The x-ray radiation was collimated to a single 280 μm wide microbeam at entrance. The microbeam beam pattern was recorded using EBT2 Gafchromic{sup ©} films. For the feasibility study, a strip of EBT2 film was attached to an oscillating mechanical phantom mimicking mouse chest respiratory motion. The servo arm was put against a pressure sensor to monitor the motion. The film was irradiated with three microbeams under gated and nongated conditions and the full width at half maximums and PVDRs were compared. An in vivo study was also performed with adult male athymic mice. The liver was chosen as the target organ for proof of concept due to its large motion during respiration compared to other organs. The mouse was immobilized in a specialized mouse bed and anesthetized using isoflurane. A pressure sensor was attached to a mouse's chest to monitor its respiration. The output signal triggered the electron extraction voltage of the field emission source such that x-ray was generated only during a

  13. A Mean Field Approach to Self-Organization in Spatially Extended Perception-Action and Psychological Systems

    NASA Astrophysics Data System (ADS)

    Frank, Till; Beek, Peter

    It is argued that perception-action systems should be considered as spatially extended systems on account of (i) the presence of spatially distributed synchronized brain activity during the performance of perceptual-motor tasks, and (ii) the failure of conventional zero-dimensional theoretical approaches to deal with multistable perception-action systems and hysteresis in the presence of noise. It is shown that in spatially extended systems self-organization can arise due to the emergence of mean field attractors. This mean field approach is exemplified for a particular class of perception-action systems, namely, rhythmic movements. In addition, clinical implications of the mean field approach and the notion of spatially extended perception-action systems are briefly discussed in the context of psychotherapy and Parkinson's disease.

  14. Reverberation Chamber Uniformity Validation and Radiated Susceptibility Test Procedures for the NASA High Intensity Radiated Fields Laboratory

    NASA Technical Reports Server (NTRS)

    Koppen, Sandra V.; Nguyen, Truong X.; Mielnik, John J.

    2010-01-01

    The NASA Langley Research Center's High Intensity Radiated Fields Laboratory has developed a capability based on the RTCA/DO-160F Section 20 guidelines for radiated electromagnetic susceptibility testing in reverberation chambers. Phase 1 of the test procedure utilizes mode-tuned stirrer techniques and E-field probe measurements to validate chamber uniformity, determines chamber loading effects, and defines a radiated susceptibility test process. The test procedure is segmented into numbered operations that are largely software controlled. This document is intended as a laboratory test reference and includes diagrams of test setups, equipment lists, as well as test results and analysis. Phase 2 of development is discussed.

  15. Characteristic of the radiation field in low Earth orbit and in deep space.

    PubMed

    Reitz, Guenther

    2008-01-01

    The radiation exposure in space by cosmic radiation can be reduced through careful mission planning and constructive measures as example the provision of a radiation shelter, but it cannot be completely avoided. The reason for that are the extreme high energies of particles in this field and the herewith connected high penetration depth in matter. For missions outside the magnetosphere ionizing radiation is recognized as the key factor through its impact on crew health and performance. In absence of sporadic solar particle events the radiation exposure in Low Earth orbit (LEO) inside Spacecraft is determined by the galactic cosmic radiation (protons and heavier ions) and by the protons inside the South Atlantic Anomaly (SAA), an area where the radiation belt comes closer to the earth surface due to a displacement of the magnetic dipole axes from the Earth's center. In addition there is an albedo source of neutrons produced as interaction products of the primary galactic particles with the atoms of the earth atmosphere. Outside the spacecraft the dose is dominated by the electrons of the horns of the radiation belt located at about 60" latitude in Polar Regions. The radiation field has spatial and temporal variations in dependence of the Earth magnetic field and the solar cycle. The complexity of the radiation field inside a spacecraft is further increased through the interaction of the high energy components with the spacecraft shielding material and with the body of the astronauts. In interplanetary missions the radiation belt will be crossed in a couple of minutes and therefore its contribution to their radiation exposure is quite small, but subsequently the protection by the Earth magnetic field is lost, leaving only shielding measures as exposure reduction means. The report intends to describe the radiation field in space, the interaction of the particles with the magnetic field and shielding material and give some numbers on the radiation exposure in low earth

  16. SENSITIVE SEARCH FOR RADIO VARIABLES AND TRANSIENTS IN THE EXTENDED CHANDRA DEEP FIELD SOUTH

    SciTech Connect

    Mooley, K. P.; Kulkarni, S. R.; Horesh, A.; Frail, D. A.; Ofek, E. O.; Miller, N. A.

    2013-05-10

    We report on an analysis of the Extended Chandra Deep Field South (E-CDFS) region using archival data from the Very Large Array, with the goal of studying radio variability and transients at the sub-milliJansky level. The 49 epochs of E-CDFS observations at 1.4 GHz sample timescales from 1 day to 3 months. We find that only a fraction (1%) of unresolved radio sources above 40 {mu}Jy are variable at the 4{sigma} level. There is no evidence that the fractional variability changes along with the known transition of radio-source populations below 1 mJy. Optical identifications of the sources show that the variable radio emission is associated with the central regions of an active galactic nucleus or a star-forming galaxy. After a detailed comparison of the efficacy of various source-finding algorithms, we use the best to carry out a transient search. No transients were found. This implies that the areal density of transients with peak flux density greater than 0.21 mJy is less than 0.37 deg{sup -2} (at a confidence level of 95%). This result is approximately an order of magnitude below the transient rate measured at 5 GHz by Bower et al. but it is consistent with more recent upper limits from Frail et al. Our findings suggest that the radio sky at 1.4 GHz is relatively quiet. For multi-wavelength transient searches, such as the electromagnetic counterparts to gravitational waves, this frequency may be optimal for reducing the high background of false positives.

  17. The use of computed radiography plates to determine light and radiation field coincidence

    SciTech Connect

    Kerns, James R.; Anand, Aman

    2013-11-15

    Purpose: Photo-stimulable phosphor computed radiography (CR) has characteristics that allow the output to be manipulated by both radiation and optical light. The authors have developed a method that uses these characteristics to carry out radiation field and light field coincidence quality assurance on linear accelerators.Methods: CR detectors from Kodak were used outside their cassettes to measure both radiation and light field edges from a Varian linear accelerator. The CR detector was first exposed to a radiation field and then to a slightly smaller light field. The light impinged on the detector's latent image, removing to an extent the portion exposed to the light field. The detector was then digitally scanned. A MATLAB-based algorithm was developed to automatically analyze the images and determine the edges of the light and radiation fields, the vector between the field centers, and the crosshair center. Radiographic film was also used as a control to confirm the radiation field size.Results: Analysis showed a high degree of repeatability with the proposed method. Results between the proposed method and radiographic film showed excellent agreement of the radiation field. The effect of varying monitor units and light exposure time was tested and found to be very small. Radiation and light field sizes were determined with an uncertainty of less than 1 mm, and light and crosshair centers were determined within 0.1 mm.Conclusions: A new method was developed to digitally determine the radiation and light field size using CR photo-stimulable phosphor plates. The method is quick and reproducible, allowing for the streamlined and robust assessment of light and radiation field coincidence, with no observer interpretation needed.

  18. Violin f-hole contribution to far-field radiation via patch near-field acoustical holography.

    PubMed

    Bissinger, George; Williams, Earl G; Valdivia, Nicolas

    2007-06-01

    The violin radiates either from dual ports (f-holes) or via surface motion of the corpus (top+ribs+back), with no clear delineation between these sources. Combining "patch" near-field acoustical holography over just the f-hole region of a violin with far-field radiativity measurements over a sphere, it was possible to separate f-hole from surface motion contributions to the total radiation of the corpus below 2.6 kHz. A0, the Helmholtz-like lowest cavity resonance, radiated essentially entirely through the f-holes as expected while A1, the first longitudinal cavity mode with a node at the f-holes, had no significant f-hole radiation. The observed A1 radiation comes from an indirect radiation mechanism, induced corpus motion approximately mirroring the cavity pressure profile seen for violinlike bowed string instruments across a wide range of sizes. The first estimates of the fraction of radiation from the f-holes F(f) indicate that some low frequency corpus modes thought to radiate only via surface motion (notably the first corpus bending modes) had significant radiation through the f-holes, in agreement with net volume changes estimated from experimental modal analysis. F(f) generally trended lower with increasing frequency, following corpus mobility decreases. The f-hole directivity (top/back radiativity ratio) was generally higher than whole-violin directivity.

  19. Vibration analysis and sound field characteristics of a tubular ultrasonic radiator.

    PubMed

    Liang, Zhaofeng; Zhou, Guangping; Zhang, Yihui; Li, Zhengzhong; Lin, Shuyu

    2006-12-01

    A sort of tubular ultrasonic radiator used in ultrasonic liquid processing is studied. The frequency equation of the tubular radiator is derived, and its radiated sound field in cylindrical reactor is calculated using finite element method and recorded by means of aluminum foil erosion. The results indicate that sound field of tubular ultrasonic radiator in cylindrical reactor appears standing waves along both its radial direction and axial direction, and amplitudes of standing waves decrease gradually along its radial direction, and the numbers of standing waves along its axial direction are equal to the axial wave numbers of tubular radiator. The experimental results are in good agreement with calculated results.

  20. Deformation field validation and inversion applied to adaptive radiation therapy

    NASA Astrophysics Data System (ADS)

    Vercauteren, Tom; De Gersem, Werner; Olteanu, Luiza A. M.; Madani, Indira; Duprez, Fréderic; Berwouts, Dieter; Speleers, Bruno; De Neve, Wilfried

    2013-08-01

    Development and implementation of chronological and anti-chronological adaptive dose accumulation strategies in adaptive intensity-modulated radiation therapy (IMRT) for head-and-neck cancer. An algorithm based on Newton iterations was implemented to efficiently compute inverse deformation fields (DFs). Four verification steps were performed to ensure a valid dose propagation: intra-cell folding detection finds zero or negative Jacobian determinants in the input DF; inter-cell folding detection is implemented on the resolution of the output DF; a region growing algorithm detects undefined values in the output DF; DF domains can be composed and displayed on the CT data. In 2011, one patient with nonmetastatic head and neck cancer selected from a three phase adaptive DPBN study was used to illustrate the algorithms implemented for adaptive chronological and anti-chronological dose accumulation. The patient received three 18F-FDG-PET/CTs prior to each treatment phase and one CT after finalizing treatment. Contour propagation and DF generation between two consecutive CTs was performed in Atlas-based autosegmentation (ABAS). Deformable image registration based dose accumulations were performed on CT1 and CT4. Dose propagation was done using combinations of DFs or their inversions. We have implemented a chronological and anti-chronological dose accumulation algorithm based on DF inversion. Algorithms were designed and implemented to detect cell folding.

  1. Non-thermal continuous and modulated electromagnetic radiation fields effects on sleep EEG of rats.

    PubMed

    Mohammed, Haitham S; Fahmy, Heba M; Radwan, Nasr M; Elsayed, Anwar A

    2013-03-01

    In the present study, the alteration in the sleep EEG in rats due to chronic exposure to low-level non-thermal electromagnetic radiation was investigated. Two types of radiation fields were used; 900 MHz unmodulated wave and 900 MHz modulated at 8 and 16 Hz waves. Animals has exposed to radiation fields for 1 month (1 h/day). EEG power spectral analyses of exposed and control animals during slow wave sleep (SWS) and rapid eye movement sleep (REM sleep) revealed that the REM sleep is more susceptible to modulated radiofrequency radiation fields (RFR) than the SWS. The latency of REM sleep increased due to radiation exposure indicating a change in the ultradian rhythm of normal sleep cycles. The cumulative and irreversible effect of radiation exposure was proposed and the interaction of the extremely low frequency radiation with the similar EEG frequencies was suggested.

  2. Orbital magnetic field driven metal-insulator transition in spinless extended Falicov-Kimball model on a triangular lattice

    NASA Astrophysics Data System (ADS)

    Yadav, Umesh K.

    2017-01-01

    Ground state properties of spinless, extended Falicov-Kimball model (FKM) on a finite size triangular lattice with orbital magnetic field normal to the lattice are studied using numerical diagonalization and Monte-Carlo simulation methods. We show that the ground state configurations of localized electrons strongly depend on the magnetic field. Magnetic field induces a metal to insulator transition accompanied by segregated phase to an ordered regular phase except at density nf = 1 / 2 of localized electrons. It is proposed that magnetic field can be used as a new tool to produce segregated phase which was otherwise accessible only either with correlated hopping or with large on-site interactions.

  3. Feasibility of EBT Gafchromic films for comparison exercises among standard beta radiation fields.

    PubMed

    Benavente, J A; Meira-Belo, L C; Reynaldo, S R; da Silva, T A

    2012-12-01

    The feasibility of using radiochromic films to verify the metrological coherence among standard beta radiation fields was evaluated. Exercises were done between two Brazilian metrology laboratories in beta fields from (90)Sr/(90)Y, (85)Kr and (147)Pm radiation sources. Results showed that the radiochromic film was useful for field mapping aiming uniformity and alignment verification and it was not reliable for absorbed dose measurements only for (147)Pm beta field.

  4. Magnetic field instability of a plasma in a beam of electromagnetic radiation

    NASA Astrophysics Data System (ADS)

    Gradov, O. M.; Stenflo, L.

    1980-04-01

    A beam of electromagnetic radiation can generate magnetic fields in plasmas. It is shown that those fields grow significantly when the incident radiation is sufficiently strong. We obtain expressions for the characteristic time of the growth of the fields as well as for their spatial distribution and point out a possible mechanism, which can lead to the formation of a quasi-stationary state. The maximum value of the magnetic field strength is estimated.

  5. Extended Field of View Soft X-Ray Fourier Transform Holography: Toward Imaging Ultrafast Evolution in a Single Shot

    SciTech Connect

    Schlotter, W.F.; Luening, J.; Rick, R.; Chen, K.; Scherz, A.; Eisebitt, S.; Guenther, C.M.; Eberhardt, W.; Hellwig, O.; Stohr, J.; /SLAC, SSRL

    2009-04-29

    Panoramic full-field imaging is demonstrated by applying spatial multiplexing to Fourier transform holography. Multiple object and reference waves extend the effective field of view for lensless imaging without compromising the spatial resolution. In this way, local regions of interest distributed throughout a sample can be simultaneously imaged with high spatial resolution. A method is proposed for capturing multiple ultrafast images of a sample with a single x-ray pulse.

  6. 14 CFR 25.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false High-intensity Radiated Fields (HIRF) Protection. 25.1317 Section 25.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...-intensity Radiated Fields (HIRF) Protection. (a) Except as provided in paragraph (d) of this section,...

  7. 14 CFR 29.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-intensity Radiated Fields (HIRF) Protection. 29.1317 Section 29.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...-intensity Radiated Fields (HIRF) Protection. (a) Except as provided in paragraph (d) of this section,...

  8. 14 CFR 23.1308 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false High-intensity Radiated Fields (HIRF) Protection. 23.1308 Section 23.1308 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Equipment General § 23.1308 High-intensity Radiated Fields (HIRF) Protection. (a) Except as provided...

  9. 14 CFR 27.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false High-intensity Radiated Fields (HIRF) Protection. 27.1317 Section 27.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...-intensity Radiated Fields (HIRF) Protection. (a) Except as provided in paragraph (d) of this section,...

  10. 14 CFR 29.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false High-intensity Radiated Fields (HIRF) Protection. 29.1317 Section 29.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...-intensity Radiated Fields (HIRF) Protection. (a) Except as provided in paragraph (d) of this section,...

  11. 14 CFR 29.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false High-intensity Radiated Fields (HIRF) Protection. 29.1317 Section 29.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...-intensity Radiated Fields (HIRF) Protection. (a) Except as provided in paragraph (d) of this section,...

  12. 14 CFR 25.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false High-intensity Radiated Fields (HIRF) Protection. 25.1317 Section 25.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...-intensity Radiated Fields (HIRF) Protection. (a) Except as provided in paragraph (d) of this section,...

  13. 14 CFR 27.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false High-intensity Radiated Fields (HIRF) Protection. 27.1317 Section 27.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...-intensity Radiated Fields (HIRF) Protection. (a) Except as provided in paragraph (d) of this section,...

  14. 14 CFR 29.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false High-intensity Radiated Fields (HIRF) Protection. 29.1317 Section 29.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...-intensity Radiated Fields (HIRF) Protection. (a) Except as provided in paragraph (d) of this section,...

  15. 14 CFR 23.1308 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false High-intensity Radiated Fields (HIRF) Protection. 23.1308 Section 23.1308 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Equipment General § 23.1308 High-intensity Radiated Fields (HIRF) Protection. (a) Except as provided...

  16. 14 CFR 27.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false High-intensity Radiated Fields (HIRF) Protection. 27.1317 Section 27.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...-intensity Radiated Fields (HIRF) Protection. (a) Except as provided in paragraph (d) of this section,...

  17. 14 CFR 23.1308 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false High-intensity Radiated Fields (HIRF) Protection. 23.1308 Section 23.1308 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Equipment General § 23.1308 High-intensity Radiated Fields (HIRF) Protection. (a) Except as provided...

  18. 14 CFR 25.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false High-intensity Radiated Fields (HIRF) Protection. 25.1317 Section 25.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...-intensity Radiated Fields (HIRF) Protection. (a) Except as provided in paragraph (d) of this section,...

  19. 14 CFR 25.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false High-intensity Radiated Fields (HIRF) Protection. 25.1317 Section 25.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...-intensity Radiated Fields (HIRF) Protection. (a) Except as provided in paragraph (d) of this section,...

  20. 14 CFR 29.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false High-intensity Radiated Fields (HIRF) Protection. 29.1317 Section 29.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...-intensity Radiated Fields (HIRF) Protection. (a) Except as provided in paragraph (d) of this section,...

  1. 14 CFR 23.1308 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false High-intensity Radiated Fields (HIRF) Protection. 23.1308 Section 23.1308 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Equipment General § 23.1308 High-intensity Radiated Fields (HIRF) Protection. (a) Except as provided...

  2. 14 CFR 27.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false High-intensity Radiated Fields (HIRF) Protection. 27.1317 Section 27.1317 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...-intensity Radiated Fields (HIRF) Protection. (a) Except as provided in paragraph (d) of this section,...

  3. 14 CFR 23.1308 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-intensity Radiated Fields (HIRF... Equipment General § 23.1308 High-intensity Radiated Fields (HIRF) Protection. (a) Except as provided in... reduce the capability of the airplane or the ability of the flightcrew to respond to an adverse...

  4. The sub-mJy radio population in the Extended Chandra Deep Field South

    NASA Astrophysics Data System (ADS)

    Bonzini, M.

    2014-06-01

    Deep radio observations provide a dust unbiased view of both black hole (BH) and star formation (SF) activity and therefore represent a powerful tool to investigate their evolution and their possible mutual influence across cosmic time. Radio astronomy is therefore becoming increasingly important for galaxy evolution studies thanks also to the many new radio facilities under construction or being planned. To maximise the potentiality of these new instruments it is crucial to make predictions on what they will observe and to see how best to complement the radio data with multi-wavelength information. These are the motivations of my Thesis in which I studied a sample of 900 sources detected in one of the deepest radio surveys ever made. The observations have been performed at 1.4 GHz with the Very Large Array on the Extended Chandra Deep Field South. I developed a multi-wavelength method to identify the optical-infrared counterparts of the radio sources and to classify them as radio-loud active galactic nuclei (RL AGNs), radio-quiet (RQ) AGNs, and star forming galaxies (SFGs). I was able for the first time to quantify the relative contribution of these different classes of sources down to a radio flux density limit of ∼30 μJy. I characterized the host galaxy properties (stellar masses, optical colors, and morphology) of the radio sources; RQ AGN hosts and SFGs have similar properties with disk morphology and blue colors while radio-loud AGN hosts are more massive, redder and mostly ellipticals. This suggests that the RQ and RL activity occurs at two different evolutionary stages of the BH-host galaxy co-evolution. The RQ phase occurs at earlier times when the galaxy is still gas rich and actively forming stars while the radio activity of the BH appears when the galaxy has already formed the bulk of its stellar population, the gas supply is lower, and the SF is considerably reduced. I quantified the star formation rate (SFR) of the radio sources using two

  5. Effects of Source Correlations on the Spectrum of Radiated Fields

    DTIC Science & Technology

    1990-09-01

    paraxial approximation, with a known result for far-zone radiant intensity of Gaussian Schell - model sources3. Spectral changes on propagation of...33 2.2 The radiation efficiency of planar Gaussian Schell - model sources ............ 34...increase in the source correlation length. Page 40. Figure 2.5: The radiation efficiency of Gaussian Schell - model sources as a function of the rms

  6. Estimating the Reliability of Electronic Parts in High Radiation Fields

    NASA Technical Reports Server (NTRS)

    Everline, Chester; Clark, Karla; Man, Guy; Rasmussen, Robert; Johnston, Allan; Kohlhase, Charles; Paulos, Todd

    2008-01-01

    Radiation effects on materials and electronic parts constrain the lifetime of flight systems visiting Europa. Understanding mission lifetime limits is critical to the design and planning of such a mission. Therefore, the operational aspects of radiation dose are a mission success issue. To predict and manage mission lifetime in a high radiation environment, system engineers need capable tools to trade radiation design choices against system design and reliability, and science achievements. Conventional tools and approaches provided past missions with conservative designs without the ability to predict their lifetime beyond the baseline mission.This paper describes a more systematic approach to understanding spacecraft design margin, allowing better prediction of spacecraft lifetime. This is possible because of newly available electronic parts radiation effects statistics and an enhanced spacecraft system reliability methodology. This new approach can be used in conjunction with traditional approaches for mission design. This paper describes the fundamentals of the new methodology.

  7. Does the upper main sequence extend across the whole H-R diagram. [radiative opacities of stellar evolution models

    NASA Technical Reports Server (NTRS)

    Stothers, R.; Chin, C.-W.

    1977-01-01

    The effect of using Carson's (1976) radiative opacities in evolutionary sequences of stellar models has been studied over the mass range from 7 to 60 solar masses. The opacities are very large in the outer part of the envelope and induce such enormous radii for masses greater than about 30 solar masses for a heavy-element fraction of 0.02 or about 20 solar masses for a heavy-element fraction of 0.04 that the evolutionary tracks during the phase of core hydrogen burning extend across the whole H-R diagram. The choice of the Schwarschild or Ledoux criterion for convection makes very little difference for the behavior of the tracks. Evolution through the effective-temperature range (in logarithms) of 3.6 to 4.0 occurs in all cases on a rapid (secular) time scale. Core helium burning takes place exclusively in the red-supergiant configuration for stellar masses exceeding 8 solar masses (heavy-element fraction of 0.02) or 6 solar masses (heavy-element fraction of 0.04). These stellar models seem to be in significantly better agreement with the observed distribution of bright stars on the H-R diagram than are the older models based on the Cox-Stewart opacities. It can be inferred that a large envelope opacity (e.g., Carson's) exists and that substantial mass loss takes place in very massive late-type supergiants.

  8. Quantum radiation produced by the entanglement of quantum fields

    NASA Astrophysics Data System (ADS)

    Iso, Satoshi; Oshita, Naritaka; Tatsukawa, Rumi; Yamamoto, Kazuhiro; Zhang, Sen

    2017-01-01

    We investigate the quantum radiation produced by an Unruh-De Witt detector in a uniformly accelerating motion coupled to the vacuum fluctuations. Quantum radiation is nonvanishing, which is consistent with the previous calculation by Lin and Hu [Phys. Rev. D 73, 124018 (2006), 10.1103/PhysRevD.73.124018]. We infer that this quantum radiation from the Unruh-De Witt detector is generated by the nonlocal correlation of the Minkowski vacuum state, which has its origin in the entanglement of the state between the left and the right Rindler wedges.

  9. Classical connection between near-field interactions and far-field radiation and the relevance to quantum photoemission

    NASA Astrophysics Data System (ADS)

    Peatross, Justin; Corson, John P.; Tarbox, Grayson

    2013-05-01

    Interference in the far-field radiation pattern emitted from a classical current distribution implies near-field work between different spatial portions of the distribution. We examine this relationship and the essential role of system geometry for the case of two oscillating dipoles and for a Gaussian current distribution. This analysis offers a compelling argument as to why the radiation from a large single-electron quantum wave packet should not exhibit the same destructive interference as that associated with a comparable classical charge density. Our discussion draws attention to the ad hoc heuristics motivating the original derivation of a quantum electron's radiation profile.

  10. Computation of radiative fields in opposed-flow flame spread in a microgravity environment

    NASA Astrophysics Data System (ADS)

    Villaraza, Jeanie Ray P.

    The purpose of this thesis is to perform radiation computations in opposed-flow flame spread in a microgravity environment. In this work, the flame spread simulations consider a thermally thin, PMMA fuel in a quiescent, microgravity environment or facing low opposed-flow velocities at ambient conditions of 1 atm and 50-50 volumetric mixture of oxygen and nitrogen. The flame spread model, which is a Computational Fluid Dynamics (CFD) model, is used for numerical simulations in combination with a radiation model. The CFD code is written in FORTRAN language, and a Matlab code is developed for plotting results. The temperature and species fields from CFD computations are used as inputs into the radiation model. Radiative quantities are calculated by using a global balance method along with the total transmittance non-homogeneous model. Radiation effect on thermocouple temperature measurement is investigated. Although this topic is well known, performing radiation correction calculations usually considers surface radiation only and not gas radiation. The inclusion of gas radiation is utilized in predicting the gas temperature that a thermocouple would measure. A narrow bed radiation model is used to determine the average incident radiative flux at a specified location from which a thermocouple temperature measurement is predicted. This study focuses on the quiescent microgravity environment only. The effect of parameters such as thermocouple surface emissivity and bead diameter are also studied. For the main part of this thesis, the effect of gas radiation on the mechanism of flame spread over a thermally thin, solid fuel in microgravity is investigated computationally. Generated radiative fields including thermal and species fields are utilized to investigate the nature of the influence of gas radiation on flame structure as well as its role in the mechanism of opposed-flow flame spread. The opposed-flow configuration considers low flow velocities including a quiescent

  11. Normal tissue toxicity after small field hypofractionated stereotactic body radiation

    PubMed Central

    Milano, Michael T; Constine, Louis S; Okunieff, Paul

    2008-01-01

    Stereotactic body radiation (SBRT) is an emerging tool in radiation oncology in which the targeting accuracy is improved via the detection and processing of a three-dimensional coordinate system that is aligned to the target. With improved targeting accuracy, SBRT allows for the minimization of normal tissue volume exposed to high radiation dose as well as the escalation of fractional dose delivery. The goal of SBRT is to minimize toxicity while maximizing tumor control. This review will discuss the basic principles of SBRT, the radiobiology of hypofractionated radiation and the outcome from published clinical trials of SBRT, with a focus on late toxicity after SBRT. While clinical data has shown SBRT to be safe in most circumstances, more data is needed to refine the ideal dose-volume metrics. PMID:18976463

  12. Sparse Matrix Motivated Reconstruction of Far-Field Radiation Patterns

    DTIC Science & Technology

    2015-03-01

    Transform (DCT). The algorithm was evaluated by using 3 antennas modeled with the high-frequency structural simulator (HFSS): a half-wave dipole, a Vivaldi...and a pyramidal horn. The 2-D radiation pattern was reconstructed for each antenna using less than 44% of the total number of measurements with low...The 3-D radiation patterns of a pyramidal horn antenna was reconstructed by using only 13% of the total number of measurements. By using the

  13. Near-field radiative thermal control with graphene covered on different materials

    NASA Astrophysics Data System (ADS)

    Wang, Ao; Zheng, Zhiheng; Xuan, Yimin

    2016-09-01

    Based on the structure of double-layer parallel plates, this paper demonstrates that thermal radiation in near field is greatly enhanced due to near-field effects, exceeding Planck‧s blackbody radiation law. To study the effect of graphene on thermal radiation in near field, the authors add graphene layer into the structure and analyze the ability of graphene to control near-field thermal radiation with different materials. The result indicates that the graphene layer effectively suppresses the near-field thermal radiation between metal plates or polar-dielectric plates, having good ability of thermal insulation. But for doped-silicon plates, depending on the specific models, graphene has different control abilities, suppressing or enhancing, and the control abilities mainly depend on the material graphene is attached to. The authors also summarize some common rules about the different abilities of graphene to control the near-field thermal radiation. In consideration of the thickness of 0.34 nm of monolayer graphene, this paper points out that graphene plays a very important role in controlling the near-field thermal radiation.

  14. Radiation detector

    DOEpatents

    Fultz, B.T.

    1980-12-05

    Apparatus is provided for detecting radiation such as gamma rays and x-rays generated in backscatter Moessbauer effect spectroscopy and x-ray spectrometry, which has a large window for detecting radiation emanating over a wide solid angle from a specimen and which generates substantially the same output pulse height for monoenergetic radiation that passes through any portion of the detection chamber. The apparatus includes a substantially toroidal chamber with conductive walls forming a cathode, and a wire anode extending in a circle within the chamber with the anode lying closer to the inner side of the toroid which has the least diameter than to the outer side. The placement of the anode produces an electric field, in a region close to the anode, which has substantially the same gradient in all directions extending radially from the anode, so that the number of avalanche electrons generated by ionizing radiation is independent of the path of the radiation through the chamber.

  15. Radiation detector

    DOEpatents

    Fultz, Brent T.

    1983-01-01

    Apparatus is provided for detecting radiation such as gamma rays and X-rays generated in backscatter Mossbauer effect spectroscopy and X-ray spectrometry, which has a large "window" for detecting radiation emanating over a wide solid angle from a specimen and which generates substantially the same output pulse height for monoenergetic radiation that passes through any portion of the detection chamber. The apparatus includes a substantially toroidal chamber with conductive walls forming a cathode, and a wire anode extending in a circle within the chamber with the anode lying closer to the inner side of the toroid which has the least diameter than to the outer side. The placement of the anode produces an electric field, in a region close to the anode, which has substantially the same gradient in all directions extending radially from the anode, so that the number of avalanche electrons generated by ionizing radiation is independent of the path of the radiation through the chamber.

  16. An analysis of the radiation from apertures in curved surfaces by the geometrical theory of diffraction. [ray technique for electromagnetic fields

    NASA Technical Reports Server (NTRS)

    Pathak, P. H.; Kouyoumjian, R. G.

    1974-01-01

    In this paper the geometrical theory of diffraction is extended to treat the radiation from apertures of slots in convex perfectly conducting surfaces. It is assumed that the tangential electric field in the aperture is known so that an equivalent infinitesimal source can be defined at each point in the aperture. Surface rays emanate from this source which is a caustic of the ray system. A launching coefficient is introduced to describe the excitation of the surface ray modes. If the field radiated from the surface is desired, the ordinary diffraction coefficients are used to determine the field of the rays shed tangentially from the surface rays. The field of the surface ray modes is not the field on the surface; hence if the mutual coupling between slots is of interest, a second coefficient related to the launching coefficient must be employed. In the region adjacent to the shadow boundary, the component of the field directly radiated from the source is represented by Fock-type functions. In the illuminated region the incident radiation from the source (this does not include the diffracted field components) is treated by geometrical optics. This extension of the geometrical theory of diffraction is applied to calculate the radiation from slots on elliptic cylinders, spheres, and spheroids.

  17. [Formation of optimum dose fields in contact radiation therapy of malignant tumors].

    PubMed

    Klepper, L Ia

    2003-01-01

    The definition of the homogeneity of a dose field in the contact radiation therapy for malignant tumors is introduced. The mathematical interpretation of problems in the formation of optimum dose fields, to which the maximum homogeneity of a dose field at the site of lesion corresponds, is presented. It is shown that the problems in the formation of optimum dose fields may be divided into two subsets in relation to whether the sources of radiation are located at the site of lesion or adjacent to the latter (application techniques of radiation). An analytical method for solving a problem in the formation of an optimal dose field in the ring circle by means of one ring source of radiation (the first type of problems). The investigation was conducted with the support of the Russian Fund of Fundamental Investigations (RFFI 01-01-00137).

  18. High energy neutron response characteristics of a passive survey instrument for the determination of cosmic radiation fields in aircraft.

    PubMed

    Bartlett, D T; Tanner, R J; Hager, L G

    2002-01-01

    A passive survey instrument has been developed for the determination of cosmic radiation fields in aircraft. The instrument contains 30 TLDs and 36 PADC etched track detectors in order to obtain the required precision and an isotropic response. Two active electronic personal dosemeters are included to record the time profile of the field intensity. The instrument is robust and reliable, and is particularly useful to verify values of route doses based on calculations. The energy of the neutron component of the field to be determined extends to over 500 MeV, but with the majority of the dose equivalent below 200 MeV. The results are reported of measurements at Uppsala University and Physikalisch-Technische Bundesanstalt of the response characteristics of the instrument to quasi-monoenergetic neutrons in the energy range 60 to 180 MeV and for monoenergetic neutrons of energy from 70 keV to 14.7 MeV.

  19. Implicit Solution of the Four-field Extended-magnetohydroynamic Equations using High-order High-continuity Finite Elements

    SciTech Connect

    S.C. Jardin; J.A. Breslau

    2004-12-17

    Here we describe a technique for solving the four-field extended-magnetohydrodynamic (MHD) equations in two dimensions. The introduction of triangular high-order finite elements with continuous first derivatives (C{sup 1} continuity) leads to a compact representation compatible with direct inversion of the associated sparse matrices. The split semi-implicit method is introduced and used to integrate the equations in time, yielding unconditional stability for arbitrary time step. The method is applied to the cylindrical tilt mode problem with the result that a non-zero value of the collisionless ion skin depth will increase the growth rate of that mode. The effect of this parameter on the reconnection rate and geometry of a Harris equilibrium and on the Taylor reconnection problem is also demonstrated. This method forms the basis for a generalization to a full extended-MHD description of the plasma with six, eight, or more scalar fields.

  20. Russian investigations in the field of atmospheric radiation in 2011-2014

    NASA Astrophysics Data System (ADS)

    Timofeev, Yu. M.; Shul'gina, E. M.

    2016-09-01

    A short survey prepared by the Russian Commission on Atmospheric Radiation contains the most significant results of work in the field of atmospheric-radiation studies performed in 2011-2014. It is part of the Russian National Report on Meteorology and Atmospheric Sciences prepared for the International Association on Meteorology and Atmospheric Sciences (IAMAS)1. During this period, the Russian Commission on Atmospheric Radiation, jointly with the concerned departments and organizations, organized two International Symposiums on Radiation and Dynamics (ISARD-2011 and ISARD-2013). At these conferences, the central problems in modern atmospheric physics were discussed: radiative transfer (RT) and atmospheric optics; greenhouse gases, clouds, and aerosols; remote methods of measurements; and new measurement data. This survey presents six directions covering the whole spectrum of investigations performed in the field of atmospheric radiation.

  1. Russian investigations in the field of atmospheric radiation in 2007-2010

    NASA Astrophysics Data System (ADS)

    Timofeev, Yu. M.; Shul'gina, E. M.

    2013-01-01

    A short survey prepared by the Russian Commission on Atmospheric Radiation contains the most significant results of works in the field of atmospheric-radiation studies performed in 2007-2010. It is part of the Russian National Report on Meteorology and Atmospheric Sciences prepared for the International Association on Meteorology and Atmospheric Sciences (IAMAS). During this period, the Russian Commission on Atmospheric Radiation, jointly with concerned departments and organizations, ran the conference "Physics and Education," dedicated to the 75th anniversary of the Department of Physics at St. Petersburg State University (2007); the International Symposium of CIS Countries "Atmospheric Radiation and Dynamics" (2009); and the 5th International Conference "Atmospheric Physics, Climate, and Environment" (2010). At the conferences, central problems in modern atmosphere physics were discussed: radiative transfer and atmospheric optics; greenhouse gases, clouds, and aerosols; remote methods of measurements; and new measurement data. This survey presents five directions covering the whole spectrum of investigations performed in the field of atmospheric radiation.

  2. Raman distributed temperature measurement at CERN high energy accelerator mixed field radiation test facility (CHARM)

    NASA Astrophysics Data System (ADS)

    Toccafondo, Iacopo; Nannipieri, Tiziano; Signorini, Alessandro; Guillermain, Elisa; Kuhnhenn, Jochen; Brugger, Markus; Di Pasquale, Fabrizio

    2015-09-01

    In this paper we present a validation of distributed Raman temperature sensing (RDTS) at the CERN high energy accelerator mixed field radiation test facility (CHARM), newly developed in order to qualify electronics for the challenging radiation environment of accelerators and connected high energy physics experiments. By investigating the effect of wavelength dependent radiation induced absorption (RIA) on the Raman Stokes and anti-Stokes light components in radiation tolerant Ge-doped multi-mode (MM) graded-index optical fibers, we demonstrate that Raman DTS used in loop configuration is robust to harsh environments in which the fiber is exposed to a mixed radiation field. The temperature profiles measured on commercial Ge-doped optical fibers is fully reliable and therefore, can be used to correct the RIA temperature dependence in distributed radiation sensing systems based on P-doped optical fibers.

  3. Radiation fields from neutron generators shielded with different materials

    NASA Astrophysics Data System (ADS)

    Chichester, D. L.; Blackburn, B. W.

    2007-08-01

    As a general guide for assessing radiological conditions around a DT neutron generator numerical modeling has been performed to assess neutron and photon dose profiles for a variety of shield materials ranging from 1 to 100 cm thick. In agreement with accepted radiation safety practices high-Z materials such as bismuth and lead have been found to be ineffective biological shield materials, owing in part to the existence of (n,2n) reaction channels available with 14.1 MeV DT neutrons, while low-Z materials serve as effective shields for these sources. Composite materials such as a mixture of polyethylene and bismuth, or regular concrete, are ideal shield materials for neutron generator radiation because of their ability to attenuate internally generated photon radiation resulting from neutron scattering and capture within the shields themselves.

  4. ETIPS: Using Cases with Virtual Schools to Prepare for, Extend, and Deepen Preservice Teachers' Field Experiences

    ERIC Educational Resources Information Center

    Dexter, Sara L.; Riedel, Eric; Scharber, Cassandra

    2008-01-01

    Field experiences are identified as an important component in the preparation of new teachers. As such, methods to supplement field experiences with pre- and post-activities that ready preservice teachers to effectively learn from them warrant further examination. This paper presents one tool that has been used successfully to improve preservice…

  5. Extending the Ion Capacity of a Linear Ion Trap Using Nonlinear Radio Frequency Fields.

    PubMed

    Guna, Mircea

    2015-12-01

    Mass selective axial ejection (MSAE) from a low pressure linear ion trap (LIT) is investigated in the presence of added auxiliary nonlinear radio frequency (rf) fields. Nonlinear rf fields allow ions to be ejected with high sensitivity at large excitation amplitudes and reduced deleterious effects of space charge. These permit the operation of the LIT at ion populations considerably larger than the space charge limit usually observed in the absence of the nonlinear fields while maintaining good spectral resolution and mass accuracy. Experimental data show that the greater the strength of the nonlinear field, the less the effects of space charge on mass assignment and peak width. The only deleterious effect is a slight broadening of the mass spectral peaks at the highest values of added nonlinear fields used. Graphical Abstract ᅟ.

  6. Quantum radiation of Maxwell’s electromagnetic field in nonstationary Kerr-de Sitter black hole

    NASA Astrophysics Data System (ADS)

    Ibungochouba Singh, T.; Ablu Meitei, I.; Yugindro Singh, K.

    2016-03-01

    Quantum radiation properties of nonstationary Kerr-de Sitter (KdS) black hole is investigated using the method of generalized tortoise coordinate transformation. The locations of horizons and the temperature of the thermal radiation as well as the maximum energy of the nonthermal radiation are derived. It is found that the surface gravity and the Hawking temperature depend on both time and different angles. An extra coupling effect is obtained in the thermal radiation spectrum of Maxwell’s electromagnetic field equations which is absent in the thermal radiation spectrum of scalar particles. Further, the chemical potential derived from the thermal radiation spectrum of scalar particle has been found to be equal to the highest energy of the negative energy state of the scalar particle in the nonthermal radiation for KdS black hole. It is also shown that the generalized tortoise coordinate transformation produces a constant term in the expression of the surface gravity and Hawking temperature.

  7. Extending field life in offshore Gulf of Mexico using 3-D seismic survey

    SciTech Connect

    Bulling, T.P.; Olsen, R.S. )

    1990-05-01

    Discovered by ARCO in 1967, the High Island 24L field (lower Miocene) is located in the Texas state waters of the Gulf of Mexico. By 1986, the field had produced 320 billion ft{sup 3} of gas and 3.0 million bbl of oil. An engineering field study completed in 1986 showed the field was declining and would be unprofitable within 3 yr. Study of reservoir maps revealed three basin problems: volumetric reserve calculations were less than reserves produced, hydrocarbon-water contacts were inconsistent between wells thought to be in communication, and ultimate recoveries could not be accurately calculated. Attempts to remap the field with the existing two-dimensional seismic data base and well data proved unsuccessful. In 1986, a three-dimensional seismic survey was acquired in an effort to evaluate the true present worth and potential of the field. Remapping of 30 reservoir horizons began in 1987. The integration of detailed well log correlations tied to the dense grid of quality three dimensional seismic data improved the reservoir maps. These maps helped resolve engineering problems by defining the configuration of the reservoirs more accurately. Reservoir maps now closely match volumetrics, fluid contacts within reservoir units are consistent, and a better definition of extension well opportunities exists. The authors study resulted in six additional wells. These wells along with engineering modifications and operations cost containment resulted in the extension of the economic life of the High Island 24-L field by at least 8 yr.

  8. Hot accretion disks with pairs: Effects of magnetic field and thermal cyclocsynchrotron radiation

    NASA Technical Reports Server (NTRS)

    Kusunose, Masaaki; Zdziarski, Andrzej A.

    1994-01-01

    We show the effects of thermal cyclosynchrotron radiation and magnetic viscosity on the structure of hot, two-temperature accretion disks. Magnetic field, B, is assumed to be randomly oriented and the ratio of magnetic pressure to either gas pressure, alpha = P(sub mag)/P(sub gas), or the sum of the gas and radiation pressures, alpha = (P(sub mag)/P(sub gas) + P(sub rad)), is fixed. We find those effects do not change the qualitative properties of the disks, i.e., there are still two critical accretion rates related to production of e(sup +/-) pairs, (M dot)((sup U)(sub cr)) and (M dot)((sup L)(sub cr)), that affect the number of local and global disk solutions, as recently found by Bjoernsson and Svensson for the case with B = 0. However, a critical value of the alpha-viscosity parameter above which those critical accretion rates disappear becomes smaller than alpha(sub cr) = 1 found in the case of B = 0, for P(sub mag) = alpha(P(sub gas) + P(sub rad)). If P(sub mag) = alpha P(sub gas), on the other hand, alpha(sub cr) is still about unity. Moreover, when Comptonized cyclosynchrotron radiation dominates Comptonized bremsstrahlung, radiation from the disk obeys a power law with the energy spectral index of approximately 0.5, in a qualitative agreement with X-ray observations of active galactic nuclei (AGNS) and Galactic black hole candidates. We also extend the hot disk solutions for P(sub mag) = alpha(P(sub gas) + P(sub rad)) to the effectively optically thick region, where they merge with the standard cold disk solutions. We find that the mapping method by Bjoernsson and Svensson gives a good approximation to the disk structure in the hot region and show where it breaks in the transition region. Finally, we find a region in the disk parameter space with no solutions due to the inability of Coulomb heating to supply enough energy to electrons.

  9. LETTER TO THE EDITOR: Comments on 'Cellular response to modulated radiation fields'

    NASA Astrophysics Data System (ADS)

    Ross, C. K.; Klassen, N. V.

    2009-03-01

    The authors of a recent paper (Claridge Mackonis et al 2007 Phys. Med. Biol. 52 5469-82) measured cell survival in spatially modulated radiation fields. They claim to have identified two new types of radiation-induced bystander effect. We conclude that their claims are not supported by their data.

  10. RHrFPGA Radiation-Hardened Re-programmable Field-Programmable Gate Array

    NASA Technical Reports Server (NTRS)

    Sanders, A. B.; LaBel, K. A.; McCabe, J. F.; Gardner, G. A.; Lintz, J.; Ross, C.; Golke, K.; Burns, B.; Carts, M. A.; Kim, H. S.

    2004-01-01

    Viewgraphs on the development of the Radiation-Hardened Re-programmable Field-Programmable Gate Array (RHrFPGA) are presented. The topics include: 1) Radiation Test Suite; 2) Testing Interface; 3) Test Configuration; 4) Facilities; 5) Test Programs; 6) Test Procedure; and 7) Test Results. A summary of heavy ion and proton testing is also included.

  11. Analytical formulation of the radiation field of printed antennas in the presence of artificial magnetic superstrates

    NASA Astrophysics Data System (ADS)

    Attia, Hussein; Yousefi, Leila; Siddiqui, Omar; Ramahi, Omar M.

    2011-06-01

    In this paper, the cavity model of a microstrip patch antenna in conjunction with the reciprocity theorem is used to develop a fast analytical solution for the radiation field of a microstrip patch antenna loaded with a novel artificial magnetic superstrate and to investigate the effect of the engineered superstrate layer on the directivity and radiation pattern of the printed patch antenna.

  12. A nonequilibrium statistical field theory of swarms and other spatially extended complex systems

    SciTech Connect

    Millonas, M.M. Santa Fe Inst., NM )

    1993-01-01

    A class of models with applications to swarm behavior as well as many other types of spatially extended complex biological and physical systems is studied. Internal fluctuations can play an active role in the organization of the phase structure of such systems. Consequently, it is not possible to fully understand the behavior of these systems without explicitly incorporating the fluctuations. In particular, for the class of models studied here the effect of internal fluctuations due to finite size is a renormalized decrease in the temperature near the point of spontaneous symmetry breaking. We briefly outline how these models can be applied to the behavior of an ant swarm.

  13. A nonequilibrium statistical field theory of swarms and other spatially extended complex systems

    SciTech Connect

    Millonas, M.M. |

    1993-07-01

    A class of models with applications to swarm behavior as well as many other types of spatially extended complex biological and physical systems is studied. Internal fluctuations can play an active role in the organization of the phase structure of such systems. Consequently, it is not possible to fully understand the behavior of these systems without explicitly incorporating the fluctuations. In particular, for the class of models studied here the effect of internal fluctuations due to finite size is a renormalized decrease in the temperature near the point of spontaneous symmetry breaking. We briefly outline how these models can be applied to the behavior of an ant swarm.

  14. Extended parametric gain range in photonic crystal fibers with strongly frequency-dependent field distributions.

    PubMed

    Petersen, Sidsel R; Alkeskjold, Thomas T; Olausson, Christina B; Lægsgaard, Jesper

    2014-08-15

    The parametric gain range of a degenerate four-wave mixing process is determined in the undepleted pump regime. The gain range is considered with and without taking the mode field distributions of the four-wave mixing components into account. It is found that the mode field distributions have to be included to evaluate the parametric gain correctly in dispersion-tailored speciality fibers and that mode profile engineering can provide a way to increase the parametric gain range.

  15. Wave field synthesis of moving virtual sound sources with complex radiation properties.

    PubMed

    Ahrens, Jens; Spors, Sascha

    2011-11-01

    An approach to the synthesis of moving virtual sound sources with complex radiation properties in wave field synthesis is presented. The approach exploits the fact that any stationary sound source of finite spatial extent radiates spherical waves at sufficient distance. The angular dependency of the radiation properties of the source under consideration is reflected by the amplitude and phase distribution on the spherical wave fronts. The sound field emitted by a uniformly moving monopole source is derived and the far-field radiation properties of the complex virtual source under consideration are incorporated in order to derive a closed-form expression for the loudspeaker driving signal. The results are illustrated via numerical simulations of the synthesis of the sound field of a sample moving complex virtual source.

  16. INVESTIGATION OF THE EXTENDED RANGE REM-COUNTER SMARTREM-LINUS IN REFERENCE AND WORKPLACE FIELDS EXPECTED AROUND HIGH-ENERGY ACCELERATORS.

    PubMed

    Hohmann, Eike; Trovati, S; Strauch, U; Mayer, S

    2016-09-01

    Radiation survey instrumentation is adequate for the use around high-energy accelerators if capable to measure the dose arising from neutrons with energies ranging from thermal up to a few gigaelectronvolts. The SmartREM-LINUS is a commercial extended range rem-counter, consisting of a central (3)He-proportional counter surrounded by a spherical moderator made of borated polyethylene with an internal shield made of lead. The dose rate indicated by the SmartREM-LINUS was investigated for two different irradiation conditions. The linearity and the angular dependence of the indicated dose rate were investigated using reference neutron fields produced by (241)AmBe and (252)Cf. Additional measurements were performed in two different workplace fields with a component of neutrons with energies >20 MeV, namely the CERN-EU high-energy reference field and near the beam dump of the SwissFEL injector test facility. The measured dose rates were compared to a commercial rem-counter (WENDI2) and the results of Monte Carlo simulations.

  17. Topological Duality Between Real Scalar and Spinor Fields in Quantum Field Theory, Cosmology, Quantum Theories of Fundamental Extended Objects

    NASA Astrophysics Data System (ADS)

    Goncharov, Yu. P.

    This survey is devoted to possible manifestations of remarkable topological duality between real scalar and spinor fields (TDSS) existing on a great number of manifolds important in physical applications. The given manifestations are demonstrated to occur within the framework of miscellaneous branches in ordinary and supersymmetric quantum field theories, supergravity, Kaluza-Klein type theories, cosmology, strings, membranes and p-branes. All this allows one to draw the condusion that the above duality will seem to be an essential ingredient in many questions of present and future investigations.

  18. FALCON: a concept to extend adaptive optics corrections to cosmological fields

    NASA Astrophysics Data System (ADS)

    Hammer, Francois; Puech, Mathieu; Assemat, Francois F.; Gendron, Eric; Sayede, Frederic; Laporte, Philippe; Marteaud, Michel; Liotard, Arnaud; Zamkotsian, Frederic

    2004-07-01

    FALCON is an original concept for a next generation spectrograph at ESO VLT or at future ELTs. It is a spectrograph including multiple small integral field units (IFUs) which can be deployed within a large field of view such as that of VLT/GIRAFFE. In FALCON, each IFU features an adaptive optics correction using off-axis natural reference stars in order to combine, in the 0.8 - 1.8 μm wavelength range, spatial and spectral resolutions (0.1 - 0.15 arcsec and R = 1000 +/- 5000). These conditions are ideally suited for distant galaxy studies, which should be done within fields of view larger than the galaxy clustering scales (4 - 9 Mpc), i.e. foV > 100 arcmin. Instead of compensating the whole field, the adaptive correction will be performed locally on each IFU. This implies to use small miniaturized devices both for adaptive optics correction and wavefront sensing. Applications to high latitude fields imply to use atmospheric tomography because the stars required for wavefront sensing will be in most of the cases far outside the isoplanatic patch.

  19. The high energy gamma-ray background and the interstellar radiation field

    NASA Astrophysics Data System (ADS)

    Chary, Ranga-Ram

    This thesis provides an independent estimate of the high latitude (! b! > 20°) contribution to the E > 30 MeV gamma-ray background from Galactic nucleon-nucleon, electron bremsstrahlung and inverse Compton processes. In particular, the inverse Compton contribution has been estimated for different cosmic ray electron distributions and after factoring in the anisotropy in the interstellar radiation field and the anisotropic Klein-Nishina scattering cross section. A model for the interstellar radiation field from 0.1 μm to 1000 μm is also presented to fit the intensities observed by recent satellite experiments, especially the DIRBE and FIRAS instruments on COBE. I find that the emission from the inverse Compton process when the anisotropy in the radiation field is included can be higher by up to 50% when compared to estimates that adopt an isotropic radiation field. Simulated inverse Compton maps with a cosmic ray electron distribution represented by a ``pill box'' extending up to a distance of 5 kpc above the Galactic plane provide better fits to the EGRET intensity maps suggesting that the cosmic ray halo may be larger than previously thought. With this distribution, I find that the net contribution from the IC process to the gamma-ray background can be as high as 20% at high Galactic latitudes. Fitting for the Galactic components of gamma-ray emission confirms the existence of an isotropic component with an intensity that can be represented by the form 27.7 × E(MeV)-2.16 photons m-2 s-1 sr -1 MeV-1, in excellent agreement with previous estimates. The spectrum of the isotropic component further argues strongly in favor of unresolved gamma-ray blazars being the source of this emission. Introduction of an anisotropic component improves the quality of the fits. However, this component, which could potentially arise from the dark matter in the Galactic halo, is not well characterized by a single power law which might be associated with any single dark matter

  20. VOYAGER OBSERVATIONS OF THE DIFFUSE FAR-ULTRAVIOLET RADIATION FIELD

    SciTech Connect

    Murthy, Jayant; Henry, Richard Conn; Holberg, Jay B.

    2012-03-01

    The two Voyager spacecraft have completed their planetary exploration mission and are now probing the outer realms of the heliosphere. The Voyager ultraviolet spectrometers continued to operate well after the Voyager 2 Neptune encounter in 1989. We present a complete database of diffuse radiation observations made by both Voyagers: a total of 1943 spectra (500-1600 A) scattered throughout the sky. These include observations of dust-scattered starlight, emission lines from the hot interstellar medium, and a number of locations where no diffuse radiation was detected, with the very low upper limit of about 25 photons cm{sup -2} s{sup -1} sr{sup -1} A{sup -1}. Many of these observations were from late in the mission when there was significantly less contribution from interplanetary emission lines and thus less contamination of the interstellar signal.

  1. Extended depth-of-field iris recognition system for a workstation environment

    NASA Astrophysics Data System (ADS)

    Narayanswamy, Ramkumar; Silveira, Paulo E. X.; Setty, Harsha; Pauca, V. P.; van der Gracht, Joseph

    2005-03-01

    Iris recognition imaging is attracting considerable interest as a viable alternative for personal identification and verification in many defense and security applications. However current iris recognition systems suffer from limited depth of field, which makes usage of these systems more difficult by an untrained user. Traditionally, the depth of field is increased by reducing the imaging system aperture, which adversely impacts the light capturing power and thus the system signal-to-noise ratio (SNR). In this paper we discuss a computational imaging system, referred to as Wavefront Coded(R) imaging, for increasing the depth of field without sacrificing the SNR or the resolution of the imaging system. This system employs a especially designed Wavefront Coded lens customized for iris recognition. We present experimental results that show the benefits of this technology for biometric identification.

  2. Effects of external radiation fields on line emission—application to star-forming regions

    SciTech Connect

    Chatzikos, Marios; Ferland, G. J.; Williams, R. J. R.; Porter, Ryan; Van Hoof, P. A. M.

    2013-12-20

    A variety of astronomical environments contain clouds irradiated by a combination of isotropic and beamed radiation fields. For example, molecular clouds may be irradiated by the isotropic cosmic microwave background, as well as by a nearby active galactic nucleus. These radiation fields excite atoms and molecules and produce emission in different ways. We revisit the escape probability theorem and derive a novel expression that accounts for the presence of external radiation fields. We show that when the field is isotropic the escape probability is reduced relative to that in the absence of external radiation. This is in agreement with previous results obtained under ad hoc assumptions or with the two-level system, but can be applied to complex many-level models of atoms or molecules. This treatment is in the development version of the spectral synthesis code CLOUDY. We examine the spectrum of a Spitzer cloud embedded in the local interstellar radiation field and show that about 60% of its emission lines are sensitive to background subtraction. We argue that this geometric approach could provide an additional tool toward understanding the complex radiation fields of starburst galaxies.

  3. Polarization of atomic radiation in stochastic plasma fields

    SciTech Connect

    Savchenko, V.I.; Fisch, N.J.

    1997-05-12

    When a laser pulse of certain polarization or an electron beam excites atoms in a plasma, the atomic spectrum of the radiation emitted by the atoms exhibits differently polarized line core and line wings. This unusual effect, which is predicted to occur under a variety of conditions, can be accompanied by the appearance of the forbidden component in the spectrum, with polarization opposite to that of the exciting laser pulse.

  4. Potential scattering of electrons in a quantized radiation field

    NASA Astrophysics Data System (ADS)

    Bergou, J.; Ehlotzky, F.

    1986-05-01

    Potential scattering of electrons in a strong laser field is reconsidered. The laser beam is described by a quantized single-mode plane-wave field with a finite number of quanta in the mode. The scattering amplitude is expanded in powers of the potential, and the first two Born terms are considered. It is shown that in the limit of an infinite number of field quanta, the Kroll-Watson approximation is recovered. Additional insight is gained into the validity of this low-frequency theorem. The approach rests on the introduction of electron-dressed quantized-field states. Relations to earlier work are indicated.

  5. Extending the field of view of KD/asterisk/P electrooptic modulators

    NASA Technical Reports Server (NTRS)

    West, E. A.

    1978-01-01

    The use of KD(asterisk)P as a polarization rotator has been limited to small field of view instruments. To investigate this limitation, the index ellipsoid is used to describe the optical properties of KD(asterisk)P and to calculate the retardance and fast axis as a function of the angle of incidence and voltage. Computed converging light patterns are then compared with observed intensity patterns formed by KD(asterisk)P. Finally, computed intensity patterns are used to demonstrate how the field of view of KD(asterisk)P can be increased when properly aligned with a positive uniaxial crystal.

  6. Signature of open magnetic field lines in the extended solar corona and of solar wind acceleration

    NASA Technical Reports Server (NTRS)

    Antonucci, E.; Giordano, S.; Benna, C.; Kohl, J. L.; Noci, G.; Michels, J.; Fineschi, S.

    1997-01-01

    The observations carried out with the ultraviolet coronagraph spectrometer onboard the Solar and Heliospheric Observatory (SOHO) are discussed. The purpose of the observations was to determine the line of sight and radial velocity fields in coronal regions with different magnetic topology. The results showed that the regions where the high speed solar wind flows along open field lines are characterized by O VI 1032 and HI Lyman alpha 1216 lines. The global coronal maps of the line of sight velocity were reconstructed. The corona height, where the solar wind reaches 100 km/s, was determined.

  7. Axial acoustic radiation force on a sphere in Gaussian field

    SciTech Connect

    Wu, Rongrong; Liu, Xiaozhou Gong, Xiufen

    2015-10-28

    Based on the finite series method, the acoustical radiation force resulting from a Gaussian beam incident on a spherical object is investigated analytically. When the position of the particles deviating from the center of the beam, the Gaussian beam is expanded as a spherical function at the center of the particles and the expanded coefficients of the Gaussian beam is calculated. The analytical expression of the acoustic radiation force on spherical particles deviating from the Gaussian beam center is deduced. The acoustic radiation force affected by the acoustic frequency and the offset distance from the Gaussian beam center is investigated. Results have been presented for Gaussian beams with different wavelengths and it has been shown that the interaction of a Gaussian beam with a sphere can result in attractive axial force under specific operational conditions. Results indicate the capability of manipulating and separating spherical spheres based on their mechanical and acoustical properties, the results provided here may provide a theoretical basis for development of single-beam acoustical tweezers.

  8. ANOLE Portable Radiation Detection System Field Test and Evaluation Campaign

    SciTech Connect

    Chris A. Hodge

    2007-07-12

    Handheld, backpack, and mobile sensors are elements of the Global Nuclear Detection System for the interdiction and control of illicit radiological and nuclear materials. They are used by the U.S. Department of Homeland Security (DHS) and other government agencies and organizations in various roles for border protection, law enforcement, and nonproliferation monitoring. In order to systematically document the operational performance of the common commercial off-the-shelf portable radiation detection systems, the DHS Domestic Nuclear Detection Office conducted a test and evaluation campaign conducted at the Nevada Test Site from January 18 to February 27, 2006. Named “Anole,” it was the first test of its kind in terms of technical design and test complexities. The Anole test results offer users information for selecting appropriate mission-specific portable radiation detection systems. The campaign also offered manufacturers the opportunity to submit their equipment for independent operationally relevant testing to subsequently improve their detector performance. This paper will present the design, execution, and methodologies of the DHS Anole portable radiation detection system test campaign.

  9. Radiation Isotope Identification Device (RIIDs) Field Test and Evaluation Campaign

    SciTech Connect

    Christopher Hodge, Raymond Keegan

    2007-08-01

    Handheld, backpack, and mobile sensors are elements of the Global Nuclear Detection System for the interdiction and control of illicit radiological and nuclear materials. They are used by the U.S. Department of Homeland Security (DHS) and other government agencies and organizations in various roles for border protection, law enforcement, and nonproliferation monitoring. In order to systematically document the operational performance of the common commercial off-the-shelf portable radiation detection systems, the DHS Domestic Nuclear Detection Office conducted a test and evaluation campaign conducted at the Nevada Test Site from January 18 to February 27, 2006. Named 'Anole', it was the first test of its kind in terms of technical design and test complexities. The Anole test results offer users information for selecting appropriate mission-specific portable radiation detection systems. The campaign also offered manufacturers the opportunity to submit their equipment for independent operationally relevant testing to subsequently improve their detector performance. This paper will present the design, execution, and methodologies of the DHS Anole portable radiation detection system test campaign.

  10. Physiologically gated micro-beam radiation therapy using electronically controlled field emission x-ray source array

    NASA Astrophysics Data System (ADS)

    Chtcheprov, Pavel; Hadsell, Michael; Burk, Laurel; Ger, Rachel; Zhang, Lei; Yuan, Hong; Lee, Yueh Z.; Chang, Sha; Lu, Jianping; Zhou, Otto

    2013-03-01

    Micro-beam radiation therapy (MRT) uses parallel planes of high dose narrow (10-100 um in width) radiation beams separated by a fraction of a millimeter to treat cancerous tumors. This experimental therapy method based on synchrotron radiation has been shown to spare normal tissue at up to 1000Gy of entrance dose while still being effective in tumor eradication and extending the lifetime of tumor-bearing small animal models. Motion during the treatment can result in significant movement of micro beam positions resulting in broader beam width and lower peak to valley dose ratio (PVDR), and thus can reduce the effectiveness of the MRT. Recently we have developed the first bench-top image guided MRT system for small animal treatment using a high powered carbon nanotube (CNT) x-ray source array. The CNT field emission x-ray source can be electronically synchronized to an external triggering signal to enable physiologically gated firing of x-ray radiation to minimize motion blurring. Here we report the results of phantom study of respiratory gated MRT. A simulation of mouse breathing was performed using a servo motor. Preliminary results show that without gating the micro beam full width at tenth maximum (FWTM) can increase by 70% and PVDR can decrease up to 50%. But with proper gating, both the beam width and PVDR changes can be negligible. Future experiments will involve irradiation of mouse models and comparing histology stains between the controls and the gated irradiation.

  11. SU-E-T-361: Energy Dependent Radiation/light-Field Misalignment On Truebeam Linear Accelerator

    SciTech Connect

    Sperling, N; Tanny, S; Parsai, E

    2015-06-15

    Purpose: Verifying the co-incidence of the radiation and light field is recommended by TG-142 for monthly and annual checks. On a digital accelerator, it is simple to verify that beam steering settings are consistent with accepted and commissioned values. This fact should allow for physicists to verify radiation-light-field co-incidence for a single energy and accept that Result for all energies. We present a case where the radiation isocenter deviated for a single energy without any apparent modification to the beam steering parameters. Methods: The radiation isocenter was determined using multiple Methods: Gafchromic film, a BB test, and radiation profiles measured with a diode. Light-field borders were marked on Gafchromic film and then irradiated for all photon energies. Images of acceptance films were compared with films taken four months later. A phantom with a radio-opaque BB was aligned to isocenter using the light-field and imaged using the EPID for all photon energies. An unshielded diode was aligned using the crosshairs and then beam profiles of multiple field sizes were obtained. Field centers were determined using Omni-Pro v7.4 software, and compared to similar scans taken during commissioning. Beam steering parameter files were checked against backups to determine that the steering parameters were unchanged. Results: There were no differences between the configuration files from acceptance. All three tests demonstrated that a single energy had deviated from accepted values by 0.8 mm in the inline direction. The other two energies remained consistent with previous measurements. The deviated energy was re-steered to be within our clinical tolerance. Conclusions: Our study demonstrates that radiation-light-field coincidence is an energy dependent effect for modern linacs. We recommend that radiation-light-field coincidence be verified for all energies on a monthly basis, particularly for modes used to treat small fields, as these may drift without

  12. Model channel ion currents in NaCl-extended simple point charge water solution with applied-field molecular dynamics.

    PubMed Central

    Crozier, P S; Henderson, D; Rowley, R L; Busath, D D

    2001-01-01

    Using periodic boundary conditions and a constant applied field, we have simulated current flow through an 8.125-A internal diameter, rigid, atomistic channel with polar walls in a rigid membrane using explicit ions and extended simple point charge water. Channel and bath currents were computed from 10 10-ns trajectories for each of 10 different conditions of concentration and applied voltage. An electric field was applied uniformly throughout the system to all mobile atoms. On average, the resultant net electric field falls primarily across the membrane channel, as expected for two conductive baths separated by a membrane capacitance. The channel is rarely occupied by more than one ion. Current-voltage relations are concentration dependent and superlinear at high concentrations. PMID:11720976

  13. Modeling of cloud liquid water structure and the associated radiation field

    SciTech Connect

    Wiscombe, W.

    1995-09-01

    A 0.5{degrees}C global warming should result from every 1% decrease in global albedo. It is therefore necessary to accurately quantify the cloud radiation interaction. Most radiation calculations are one-dimensional and attempt to deal with horizontal variability using a horizontally-averaged optical depth. This study presents detailed scale-by-scale statistical analysis of the cloud liquid water content (LWC) field. The aim is to use this information to provide radiation calculations with more adequate information about inhomogeneity in cloud fields. The radiation community needs to carefully specify the minimum requirements which GCMs must include in order to treat cloud-radiation interaction correctly. This may involve GCMs predicting not only mean cloud quantities but also cloud variability. 3 figs.

  14. Basic theory for polarized, astrophysical maser radiation in a magnetic field

    NASA Technical Reports Server (NTRS)

    Watson, William D.

    1994-01-01

    Fundamental alterations in the theory and resulting behavior of polarized, astrophysical maser radiation in the presence of a magnetic field have been asserted based on a calculation of instabilities in the radiative transfer. I reconsider the radiative transfer and find that the relevant instabilities do not occur. Calculational errors in the previous investigation are identified. In addition, such instabilities would have appeared -- but did not -- in the numerous numerical solutions to the same radiative transfer equations that have been presented in the literature. As a result, all modifications that have been presented in a recent series of papers (Elitzur 1991, 1993) to the theory for polarized maser radiation in the presence of a magnetic field are invalid. The basic theory is thus clarified.

  15. Heat flux splitter for near-field thermal radiation

    SciTech Connect

    Ben-Abdallah, P.; Belarouci, A.; Frechette, L.; Biehs, S.-A.

    2015-08-03

    We demonstrate the possibility to efficiently split the near-field heat flux exchanged between graphene nano-disks by tuning their doping. This result paves the way for the development of an active control of propagation directions for heat fluxes exchanged in the near field throughout integrated nanostructured networks.

  16. Extended Lagrangian Born-Oppenheimer molecular dynamics in the limit of vanishing self-consistent field optimization

    SciTech Connect

    Souvatzis, Petros; Niklasson, Anders M. N.

    2013-12-07

    We present an efficient general approach to first principles molecular dynamics simulations based on extended Lagrangian Born-Oppenheimer molecular dynamics [A. M. N. Niklasson, Phys. Rev. Lett. 100, 123004 (2008)] in the limit of vanishing self-consistent field optimization. The reduction of the optimization requirement reduces the computational cost to a minimum, but without causing any significant loss of accuracy or long-term energy drift. The optimization-free first principles molecular dynamics requires only one single diagonalization per time step, but is still able to provide trajectories at the same level of accuracy as “exact,” fully converged, Born-Oppenheimer molecular dynamics simulations. The optimization-free limit of extended Lagrangian Born-Oppenheimer molecular dynamics therefore represents an ideal starting point for robust and efficient first principles quantum mechanical molecular dynamics simulations.

  17. WE-EF-BRA-08: Cell Survival in Modulated Radiation Fields and Altered DNA-Repair at Field Edges

    SciTech Connect

    Bartzsch, S; Oelfke, U; Eismann, S

    2015-06-15

    Purpose: Tissue damage prognoses in radiotherapy are based on clonogenic assays that provide dose dependent cell survival rates. However, recent work has shown that apart from dose, systemic reactions and cell-cell communication crucially influence the radiation response. These effects are probably a key in understanding treatment approaches such as microbeam radiation therapy (MRT). In this study we tried to quantify the effects on a cellular level in spatially modulated radiation fields. Methods: Pancreas carcinoma cells were cultured, plated and irradiated by spatially modulated radiation fields with an X-ray tube and at a synchrotron. During and after treatment cells were able to communicate via the intercellular medium. Afterwards we stained for DNA and DNA damage and imaged with a fluorescence microscope. Results: Intriguingly we found that DNA damage does not strictly increase with dose. Two cell entities appear that have either a high or a low amount of DNA lesions, indicating that DNA damage is also a cell stress reaction. Close to radiation boundaries damage-levels became alike; they were higher than expected at low and lower than expected at high doses. Neighbouring cells reacted similarly. 6 hours after exposure around 40% of the cells resembled in their reactions neighbouring cells more than randomly chosen cells that received the same dose. We also observed that close to radiation boundaries the radiation induced cell-cycle arrest disappeared and the size of DNA repair-centres increased. Conclusion: Cell communication plays an important role in the radiation response of tissues and may be both, protective and destructive. These effects may not only have the potential to affect conventional radiotherapy but may also be exploited to spare organs at risk by intelligently designing irradiation geometries. To that end intensive work is required to shed light on the still obscure processes in cell-signalling and radiation biology.

  18. Far-field pattern analysis of extended-hemispherical-lens/objective-lens antenna system at millimeter wavelengths

    NASA Astrophysics Data System (ADS)

    Dou, Wenbin; Sun, Zhong Liang; Zeng, G.

    1998-11-01

    integrated antennas have the advantages of low cost and can be readily mass produced using standard IC fabrication processes. However, integrated antennas suffer from the surface wave effect at millimeter waves. One of the ways to avoid this problem is to integrate the antennas on a dielectric lens. This structure does not support surface-waves and tend to radiate most of their power into the dielectric side making the pattern unidirectional on high dielectric constant lenses. The dielectric lens also provides mechanical rigidity and thermal stability. There are various dielectric lenses which can be used for receiver application. Among them the extended hemispherical lens is very practical, since it can synthesize other lenses such as hemispherical, hyperhemispherical, or ellipsoidal simply by varying the extension length behind the hemispherical position. In reference five, investigation on such antenna/lens system is presented. In reference 6, slot- ring antennas on dielectric lens is investigated. In many applications the extended hemispherical lens/objective lens antenna system is more attractive, because it can provide higher gain and may be used in imaging system. On the other hand, monopulse direction-finding techniques are currently the most accurate and rapid method for locating a target electronically. This antenna system can also be used as monopulse antenna. However, the treatments on such antenna system are not presented yet. In this paper, the radiation pattern of the antenna system fed by double-slot antenna are computed using ray-tracing and diffraction integration methods. Although the double-slot antenna is used as feed antenna, other antenna such as slot-ring, bow-tie antenna can be used too.

  19. Synchro-curvature radiation of charged particles in the strong curved magnetic fields

    SciTech Connect

    Kelner, S. R.; Prosekin, A. Yu.; Aharonian, F. A. E-mail: Anton.Prosekin@mpi-hd.mpg.de

    2015-01-01

    It is generally believed that the radiation of relativistic particles in a curved magnetic field proceeds in either the synchrotron or the curvature radiation modes. In this paper we show that in strong curved magnetic fields a significant fraction of the energy of relativistic electrons can be radiated away in the intermediate, the so-called synchro-curvature regime. Because of the persistent change of the trajectory curvature, the radiation varies with the frequency of particle gyration. While this effect can be ignored in the synchrotron and curvature regimes, the variability plays a key role in the formation of the synchro-curvature radiation. Using the Hamiltonian formalism, we find that the particle trajectory has the form of a helix wound around the drift trajectory. This allows us to calculate analytically the intensity and energy distribution of prompt radiation in the general case of magnetic bremsstrahlung in the curved magnetic field. We show that the transition to the limit of the synchrotron and curvature radiation regimes is determined by the relation between the drift velocity and the component of the particle velocity perpendicular to the drift trajectory. The detailed numerical calculations, which take into account the energy losses of particles, confirm the principal conclusions based on the simplified analytical treatment of the problem, and allow us to analyze quantitatively the transition between different radiation regimes for a broad range of initial pitch angles. These calculations demonstrate that even very small pitch angles may lead to significant deviations from the spectrum of the standard curvature radiation when it is formally assumed that a charged particle moves strictly along the magnetic line. We argue that in the case of realization of specific configurations of the electric and magnetic fields, the gamma-ray emission of the pulsar magnetospheres can be dominated by the component radiated in the synchro-curvature regime.

  20. Testing of Performance of Optical Fibers Under Irradiation in Intense Radiation Fields, When Subjected to Very High Temperatures

    SciTech Connect

    Blue, Thomas; Windl, Wolfgang; Dickerson, Bryan

    2013-01-03

    The primary objective of this project is to measure and model the performance of optical fibers in intense radiation fields when subjected to very high temperatures. This research will pave the way for fiber optic and optically based sensors under conditions expected in future high-temperature gas-cooled reactors. Sensor life and signal-to-noise ratios are susceptible to attenuation of the light signal due to scattering and absorbance in the fibers. This project will provide an experimental and theoretical study of the darkening of optical fibers in high-radiation and high-temperature environments. Although optical fibers have been studied for moderate radiation fluence and flux levels, the results of irradiation at very high temperatures have not been published for extended in-core exposures. Several previous multi-scale modeling efforts have studied irradiation effects on the mechanical properties of materials. However, model-based prediction of irradiation-induced changes in silica's optical transport properties has only recently started to receive attention due to possible applications as optical transmission components in fusion reactors. Nearly all damage-modeling studies have been performed in the molecular-dynamics domain, limited to very short times and small systems. Extended-time modeling, however, is crucial to predicting the long-term effects of irradiation at high temperatures, since the experimental testing may not encompass the displacement rate that the fibers will encounter if they are deployed in the VHTR. The project team will pursue such extended-time modeling, including the effects of the ambient and recrystallization. The process will be based on kinetic MC modeling using the concept of amorphous material consisting of building blocks of defect-pairs or clusters, which has been successfully applied to kinetic modeling in amorphized and recrystallized silicon. Using this procedure, the team will model compensation for rate effects, and the

  1. Coherent regime and far-to-near-field transition for radiative heat transfer

    NASA Astrophysics Data System (ADS)

    Tsurimaki, Yoichiro; Chapuis, Pierre-Olivier; Okajima, Junnosuke; Komiya, Atsuki; Maruyama, Shigenao; Vaillon, Rodolphe

    2017-01-01

    Radiative heat transfer between two semi-infinite parallel media is analyzed in the transition zone between the near-field and the classical macroscopic, i.e. incoherent far-field, regimes of thermal radiation, first for model gray materials and then for real metallic (Al) and dielectric (SiC) materials. The presence of a minimum in the flux-distance curve is observed for the propagative component of the radiative heat transfer coefficient, and in some cases for the total coefficient, i.e. the sum of the propagative and evanescent components. At best this reduction can reach 15% below the far-field limit in the case of aluminum. The far-to-near-field regime taking place for the distance range between the near-field and the classical macroscopic regime involves a coherent far-field regime. One of its limits can be practically defined by the distance at which the incoherent far-field regime breaks down. This separation distance below which the standard theory of incoherent thermal radiation cannot be applied anymore is found to be larger than the usual estimate based on Wien's law and varies as a function of temperature. The aforementioned effects are due to coherence, which is present despite the broadband spectral nature of thermal radiation, and has a stronger impact for reflective materials.

  2. Entanglement of particles as a result of their coupling through the common background zero-point radiation field

    NASA Astrophysics Data System (ADS)

    de la Peña, L.; Valdés-Hernández, A.; Cetto, A. M.

    2010-01-01

    This paper is intended to disclose a possible physical mechanism underlying entanglement, by allowing an (otherwise classical) system of two non-interacting particles to interact with the stochastic background zero-point radiation field. The present analysis is made in the framework of linear stochastic electrodynamics (LSED), a theory that has been shown to recover the corresponding matrix formulation of quantum mechanics when applied to a one-particle (or atomic) system. We start by briefly recalling the basic elements of LSED and then extend the theory to consider the system formed of two particles. It is found that when both particles resonate to at least one common frequency of the background field, a new class of non-factorizable states emerge that correspond just to the entangled states of quantum mechanics. In the particular case of two equal particles the ensuing states are those of maximum entanglement.

  3. Exploring graphene field effect transistor devices to improve spectral resolution of semiconductor radiation detectors

    SciTech Connect

    Harrison, Richard Karl; Howell, Stephen Wayne; Martin, Jeffrey B.; Hamilton, Allister B.

    2013-12-01

    Graphene, a planar, atomically thin form of carbon, has unique electrical and material properties that could enable new high performance semiconductor devices. Graphene could be of specific interest in the development of room-temperature, high-resolution semiconductor radiation spectrometers. Incorporating graphene into a field-effect transistor architecture could provide an extremely high sensitivity readout mechanism for sensing charge carriers in a semiconductor detector, thus enabling the fabrication of a sensitive radiation sensor. In addition, the field effect transistor architecture allows us to sense only a single charge carrier type, such as electrons. This is an advantage for room-temperature semiconductor radiation detectors, which often suffer from significant hole trapping. Here we report on initial efforts towards device fabrication and proof-of-concept testing. This work investigates the use of graphene transferred onto silicon and silicon carbide, and the response of these fabricated graphene field effect transistor devices to stimuli such as light and alpha radiation.

  4. Use of an electric field in an electrostatic liquid film radiator.

    PubMed

    Bankoff, S G; Griffing, E M; Schluter, R A

    2002-10-01

    Experimental and numerical work was performed to further the understanding of an electrostatic liquid film radiator (ELFR) that was originally proposed by Kim et al.(1) The ELFR design utilizes an electric field that exerts a normal force on the interface of a flowing film. The field lowers the pressure under the film in a space radiator and, thereby, prevents leakage through a puncture in the radiator wall. The flowing film is subject to the Taylor cone instability, whereby a cone of fluid forms underneath an electrode and sharpens until a jet of fluid is pulled toward the electrode and disintegrates into droplets. The critical potential for the instability is shown to be as much as an order of magnitude higher than that used in previous designs.(2) Furthermore, leak stoppage experiments indicate that the critical field is adequate to stop leaks in a working radiator.

  5. Radio-Optical Analysis of Extended Radio Sources in the First Look Survey Field

    NASA Astrophysics Data System (ADS)

    Paulo, C. M.; Prandoni, I.; Morganti, R.; Cress, C. M.

    2010-05-01

    We combine 610 MHz GMRT data, 1.4 GHz VLA data, and 1.4 GHz WSRT observations, encompassing a ~ 4 square degree field centered on the verification strip of the Spitzer First Look Survey field, to study radio sources down to fluxes of about 0.1 mJy. The spectral index (Figure 1) analysis shows that the majority of multi-component sources are steep-spectrum sources. Nevertheless the spread in the spectral distribution is wide, with a significant number of ultra-steep, flat or inverted sources, possibly indicating a wider range of accretion modes in fainter samples. By cross-correlating 107 multi-component radio sources with the optical catalogues of Marleau et al. (2007) and Papovich et al. (2006), 23 objects were identified.

  6. Escape of gravitational radiation from the field of massive bodies

    NASA Technical Reports Server (NTRS)

    Price, Richard H.; Pullin, Jorge; Kundu, Prasun K.

    1993-01-01

    We consider a compact source of gravitational waves of frequency omega in or near a massive spherically symmetric distribution of matter or a black hole. Recent calculations have led to apparently contradictory results for the influence of the massive body on the propagation of the waves. We show here that the results are in fact consistent and in agreement with the 'standard' viewpoint in which the high-frequency compact source produces the radiation as if in a flat background, and the background curvature affects the propagation of these waves.

  7. Stretched exponential survival statistics for microorganisms in radiation field

    NASA Astrophysics Data System (ADS)

    Plonka, Andrzej; Bogus, Wlodzimierz

    1999-11-01

    The so-called concave or tailed survival curves are reported both for multi and single species bacterial populations. Taking as an example Bacillus pumilus, frequently encountered in decontamination studies, it is shown that the tailed survival curves are adequately described by stretched (0< α<1) exponential SF=exp[-( D/ D0) α], where SF denotes the fraction of species surviving the irradiation dose D, D0 is the effective dose, and α is the dispersion parameter interpreted phenomenologically in terms of radiation sensivity distribution for single species population under the given experimental conditions.

  8. Design of mobile phone lens with extended depth of field based on point-spread function focus invariance

    NASA Astrophysics Data System (ADS)

    Sung, Hsin-Yueh; Yang, Sidney S.; Chang, Horng

    2008-08-01

    Due to the application of mobile phone lens, the clear image for the different object distance from infinity to close-up creates a new bargaining. We found that wave-front coding applied to extend the depth of field may solve this problem. By means of using cubic phase mask (CPM), the blurred point-spread function (PSF) is substantially invariant to defocus. Thus, the ideal hyperfocal distance condition can be satisfied as long as the constant blurred image can eventually be recovered by a simple digital signal processing. In this paper, we propose a different design method of computational imaging lens for mobile phone up to ideal depth of field based on PSF focus invariance. Because of the difficulty for comparing the similarity to different PSFs, we define a new metric, of correlation, to evaluate and optimize the PSF similarity. Besides, by means of adding the anti-symmetric free form phase plate at aperture stop and using the correlation and Strehl ratio as the two major optimization operands, we can get the optimum phase plate surface to achieve the required extended depth of field (EDoF). The resulted PSF on focal plane is significantly invariant to object distance varying from infinity to 10cm.

  9. Fan Noise Prediction System Development: Source/Radiation Field Coupling and Workstation Conversion for the Acoustic Radiation Code

    NASA Technical Reports Server (NTRS)

    Meyer, H. D.

    1993-01-01

    The Acoustic Radiation Code (ARC) is a finite element program used on the IBM mainframe to predict far-field acoustic radiation from a turbofan engine inlet. In this report, requirements for developers of internal aerodynamic codes regarding use of their program output an input for the ARC are discussed. More specifically, the particular input needed from the Bolt, Beranek and Newman/Pratt and Whitney (turbofan source noise generation) Code (BBN/PWC) is described. In a separate analysis, a method of coupling the source and radiation models, that recognizes waves crossing the interface in both directions, has been derived. A preliminary version of the coupled code has been developed and used for initial evaluation of coupling issues. Results thus far have shown that reflection from the inlet is sufficient to indicate that full coupling of the source and radiation fields is needed for accurate noise predictions ' Also, for this contract, the ARC has been modified for use on the Sun and Silicon Graphics Iris UNIX workstations. Changes and additions involved in this effort are described in an appendix.

  10. Modern radiation therapy for extranodal lymphomas: field and dose guidelines from the International Lymphoma Radiation Oncology Group.

    PubMed

    Yahalom, Joachim; Illidge, Tim; Specht, Lena; Hoppe, Richard T; Li, Ye-Xiong; Tsang, Richard; Wirth, Andrew

    2015-05-01

    Extranodal lymphomas (ENLs) comprise about a third of all non-Hodgkin lymphomas (NHL). Radiation therapy (RT) is frequently used as either primary therapy (particularly for indolent ENL), consolidation after systemic therapy, salvage treatment, or palliation. The wide range of presentations of ENL, involving any organ in the body and the spectrum of histological sub-types, poses a challenge both for routine clinical care and for the conduct of prospective and retrospective studies. This has led to uncertainty and lack of consistency in RT approaches between centers and clinicians. Thus far there is a lack of guidelines for the use of RT in the management of ENL. This report presents an effort by the International Lymphoma Radiation Oncology Group (ILROG) to harmonize and standardize the principles of treatment of ENL, and to address the technical challenges of simulation, volume definition and treatment planning for the most frequently involved organs. Specifically, detailed recommendations for RT volumes are provided. We have applied the same modern principles of involved site radiation therapy as previously developed and published as guidelines for Hodgkin lymphoma and nodal NHL. We have adopted RT volume definitions based on the International Commission on Radiation Units and Measurements (ICRU), as has been widely adopted by the field of radiation oncology for solid tumors. Organ-specific recommendations take into account histological subtype, anatomy, the treatment intent, and other treatment modalities that may be have been used before RT.

  11. Modern Radiation Therapy for Extranodal Lymphomas: Field and Dose Guidelines From the International Lymphoma Radiation Oncology Group

    SciTech Connect

    Yahalom, Joachim; Illidge, Tim; Specht, Lena; Hoppe, Richard T.; Li, Ye-Xiong; Tsang, Richard; Wirth, Andrew

    2015-05-01

    Extranodal lymphomas (ENLs) comprise about a third of all non-Hodgkin lymphomas (NHL). Radiation therapy (RT) is frequently used as either primary therapy (particularly for indolent ENL), consolidation after systemic therapy, salvage treatment, or palliation. The wide range of presentations of ENL, involving any organ in the body and the spectrum of histological sub-types, poses a challenge both for routine clinical care and for the conduct of prospective and retrospective studies. This has led to uncertainty and lack of consistency in RT approaches between centers and clinicians. Thus far there is a lack of guidelines for the use of RT in the management of ENL. This report presents an effort by the International Lymphoma Radiation Oncology Group (ILROG) to harmonize and standardize the principles of treatment of ENL, and to address the technical challenges of simulation, volume definition and treatment planning for the most frequently involved organs. Specifically, detailed recommendations for RT volumes are provided. We have applied the same modern principles of involved site radiation therapy as previously developed and published as guidelines for Hodgkin lymphoma and nodal NHL. We have adopted RT volume definitions based on the International Commission on Radiation Units and Measurements (ICRU), as has been widely adopted by the field of radiation oncology for solid tumors. Organ-specific recommendations take into account histological subtype, anatomy, the treatment intent, and other treatment modalities that may be have been used before RT.

  12. A comprehensive spectrometry study of a stray neutron radiation field in scanning proton therapy

    NASA Astrophysics Data System (ADS)

    Mares, Vladimir; Romero-Expósito, Maite; Farah, Jad; Trinkl, Sebastian; Domingo, Carles; Dommert, Martin; Stolarczyk, Liliana; Van Ryckeghem, Laurent; Wielunski, Marek; Olko, Pawel; Harrison, Roger M.

    2016-06-01

    The purpose of this study is to characterize the stray neutron radiation field in scanning proton therapy considering a pediatric anthropomorphic phantom and a clinically-relevant beam condition. Using two extended-range Bonner sphere spectrometry systems (ERBSS), Working Group 9 of the European Radiation Dosimetry Group measured neutron spectra at ten different positions around a pediatric anthropomorphic phantom irradiated for a brain tumor with a scanning proton beam. This study compares the different systems and unfolding codes as well as neutron spectra measured in similar conditions around a water tank phantom. The ten spectra measured with two ERBSS systems show a generally similar thermal component regardless of the position around the phantom while high energy neutrons (above 20 MeV) were only registered at positions near the beam axis (at 0°, 329° and 355°). Neutron spectra, fluence and ambient dose equivalent, H *(10), values of both systems were in good agreement (<15%) while the unfolding code proved to have a limited effect. The highest H *(10) value of 2.7 μSv Gy-1 was measured at 329° to the beam axis and 1.63 m from the isocenter where high-energy neutrons (E  ⩾  20 MeV) contribute with about 53%. The neutron mapping within the gantry room showed that H *(10) values significantly decreased with distance and angular position with respect to the beam axis dropping to 0.52 μSv Gy-1 at 90° and 3.35 m. Spectra at angles of 45° and 135° with respect to the beam axis measured here with an anthropomorphic phantom showed a similar peak structure at the thermal, fast and high energy range as in the previous water-tank experiments. Meanwhile, at 90°, small differences at the high-energy range were observed. Using ERBSS systems, neutron spectra mapping was performed to characterize the exposure of scanning proton therapy patients. The ten measured spectra provide precise information about the exposure of healthy organs to thermal

  13. Hybrid antenna sources for radiating high-power impulsive fields

    NASA Astrophysics Data System (ADS)

    Buchenauer, C. Jerald; Marek, J. Raley

    1995-09-01

    The transmission of impulsive signals through baluns and feed lines, between high-power, fast-risetime pulse generators and impulse-radiating antennas, leads to degraded system performance and increased pulse risetime due to transit-time dispersion, skin and dielectric losses, and electrical breakdown effects. These loss mechanisms are greatly reduced in system designs that eliminate feed lines and baluns by combining the antenna and generator in a single hybrid device that is compact, simple, and robust. This paper describes generators in which the antenna itself is pulse charged to hundreds of kV and subsequently shorted at the feed point by an oil spark switch. These Hertzian generators maintain conical symmetry to within a few millimeters of the feed-point switch, thus providing conditions for launching near-ideal spherical TEM step waves for driving impulse-radiating, focused-aperture antennas. Careful attention to symmetry, optical principles, and precise methods of measurement has yielded subnanosecond pulse risetimes that are more than ten times faster than predictions from spark- switch scaling laws.

  14. An Organic Field-effect Transistor with an Extended-gate Electrode Capable of Detecting Human Immunoglobulin A.

    PubMed

    Minamiki, Tsukuru; Minami, Tsuyoshi; Sasaki, Yui; Kurita, Ryoji; Niwa, Osamu; Wakida, Shin-ichi; Tokito, Shizuo

    2015-01-01

    We herein report on the development of an extended-gate type organic field-effect transistor (OFET)-based immunosensor for the detection of human immunoglobulin A (IgA). The titration results of IgA exhibited shifts in the transfer characteristics of the OFET sensor device with increasing IgA concentration. A linear detection range from 0 to 10 μg/mL was realized with a detection limit of 2.1 μg/mL, indicating that the OFET-based immunosensor can be potentially applied to the monitoring of infectious diseases and psychological stress in daily life.

  15. Effect of field-focusing and ion selectivity on the extended space charge developed at the microchannel-nanochannel interface.

    PubMed

    Liel, Uri; Leibowitz, Neta; Schiffbauer, Jarrod; Park, Sinwook; Yossifon, Gilad

    2016-08-17

    We present results demonstrating the effect of varying microchannel depth and bulk conductivity on the space charge-mediated transition between classical, diffusion-limited current and over-limiting current in microchannel-nanochannel devices. The extended space charge layer develops at the depleted microchannel-nanochannel entrance when the limiting current is exceeded and is correlated with a distinctive maximum in the dc resistance. This maximum is shown to be affected by the microchannel depth, via field-focusing, and solution conductivity. In particular, we observe that upon their increase, the maximum becomes flatter and shifts to higher voltages.

  16. Extended field-of-view in a lensless endoscope using an aperiodic multicore fiber

    NASA Astrophysics Data System (ADS)

    Sivankutty, Siddharth; Tsvirkun, Viktor; Bouwmans, Géraud; Kogan, Dani; Oron, Dan; Andresen, Esben Ravn; Rigneault, Hervé

    2016-08-01

    We investigate lensless endoscopy using coherent beam combining and aperiodic multicore fibers (MCF). We show that diffracted orders, inherent to MCF with periodically arranged cores, dramatically reduce the field of view (FoV) and that randomness in MCF core positions can increase the FoV up to the diffraction limit set by a single fiber core, while maintaining MCF experimental feasibility. We demonstrate experimentally pixelation-free lensless endoscopy imaging over a 120 micron FoV with an aperiodic MCF designed with widely spaced cores. We show that this system is suitable to perform beam scanning imaging by simply applying a tilt to the proximal wavefront.

  17. Extended depth of field in an intrinsically wavefront-encoded biometric iris camera

    NASA Astrophysics Data System (ADS)

    Bergkoetter, Matthew D.; Bentley, Julie L.

    2014-12-01

    This work describes a design process which greatly increases the depth of field of a simple three-element lens system intended for biometric iris recognition. The system is optimized to produce a point spread function which is insensitive to defocus, so that recorded images may be deconvolved without knowledge of the exact object distance. This is essentially a variation on the technique of wavefront encoding, however the desired encoding effect is achieved by aberrations intrinsic to the lens system itself, without the need for a pupil phase mask.

  18. Global and Local Gravity Field Models of the Moon Using GRAIL Primary and Extended Mission Data

    NASA Technical Reports Server (NTRS)

    Goossens, Sander; Lemoine, Frank G.; Sabaka, Terence J.; Nicholas, Joseph B.; Mazarico, Erwan; Rowlands, David D.; Loomis, Bryant D.; Chinn, Douglas S.; Neumann, Gregory A.; Smith, David E.; Zuber, Maria T.

    2015-01-01

    The Gravity Recovery and Interior Laboratory (GRAIL) mission was designed to map the structure of the lunar interior from crust to core and to advance the understanding of the Moon's thermal evolution by producing a high-quality, high-resolution map of the gravitational field of the Moon. The mission consisted of two spacecraft, which were launched in September 2011 on a Discovery-class NASA mission. Ka-band tracking between the two satellites was the single science instrument, augmented by tracking from Earth using the Deep Space Network (DSN).

  19. Terahertz Radiation from Laser Created Plasma by Applying a Transverse Static Electric Field

    NASA Astrophysics Data System (ADS)

    Fukuda, Takuya; Katahira, Koji; Yugami, Noboru; Sentoku, Yasuhiko; Sakagami, Hitoshi; Nagatomo, Hideo

    2016-10-01

    Terahertz (THz) radiation, which is emitted in narrow cone in the forward direction from laser created plasma has been observed by N.Yugami et al.. Additionally, Löffler et al. have observed that a significantly increased THz emission intensity in the forward direction when the transverse static electric field is applied to the plasma. The purpose of our study is to derive the mechanism of the THz radiation from laser created plasma by applying the transverse static electric field. To study the radiation mechanism, we conducted 2D-PIC simulation. With the static electric field of 10 kV/cm and gas density of 1020 cm-3, we obtain 1.2 THz single cycle pulse radiation, whose intensity is 1.3 ×105 W/cm2. The magnetic field called ``picket fence mode'' is generated in the laser created plasma. At the boundary surface between the plasma and vacuum, the magnetic field is canceled because eddy current flows. We conclude that the temporal behavior of the magnetic field at the boundary surface radiates the THz wave.

  20. Feasibility Study of Extended-Gate-Type Silicon Nanowire Field-Effect Transistors for Neural Recording.

    PubMed

    Kang, Hongki; Kim, Jee-Yeon; Choi, Yang-Kyu; Nam, Yoonkey

    2017-03-28

    In this research, a high performance silicon nanowire field-effect transistor (transconductance as high as 34 µS and sensitivity as 84 nS/mV) is extensively studied and directly compared with planar passive microelectrode arrays for neural recording application. Electrical and electrochemical characteristics are carefully characterized in a very well-controlled manner. We especially focused on the signal amplification capability and intrinsic noise of the transistors. A neural recording system using both silicon nanowire field-effect transistor-based active-type microelectrode array and platinum black microelectrode-based passive-type microelectrode array are implemented and compared. An artificial neural spike signal is supplied as input to both arrays through a buffer solution and recorded simultaneously. Recorded signal intensity by the silicon nanowire transistor was precisely determined by an electrical characteristic of the transistor, transconductance. Signal-to-noise ratio was found to be strongly dependent upon the intrinsic 1/f noise of the silicon nanowire transistor. We found how signal strength is determined and how intrinsic noise of the transistor determines signal-to-noise ratio of the recorded neural signals. This study provides in-depth understanding of the overall neural recording mechanism using silicon nanowire transistors and solid design guideline for further improvement and development.

  1. Three Dimensional Radiation Fields in Free Electron Lasers Using Lienard-Wiechert Fields,

    DTIC Science & Technology

    1981-10-28

    compared to 60 trad for the short pulse. It is possible to think of the resultant radiation as being generated by a long line of phased-array antenas ...cone of angular dimension given approximately by 1/No where No is the number of radiators in the antena . For the FEL, however, No represents the number

  2. [The use of a detector of the extremely weak radiation as a variometer of gravitation field].

    PubMed

    Gorshkov, E S; Bondarenko, E G; Shapovalov, S N; Sokolovskiĭ, V V; Troshichev, O A

    2001-01-01

    It was shown that the detector of extremely weak radiation with selectively increased sensitivity to the nonelectromagnetic, including the gravitational component of the spectrum of active physical fields can be used as the basis for constructing a variometer of gravitational field of a new type.

  3. Selective nitrate detection by an enzymatic sensor based on an extended-gate type organic field-effect transistor.

    PubMed

    Minami, Tsuyoshi; Sasaki, Yui; Minamiki, Tsukuru; Wakida, Shin-Ichi; Kurita, Ryoji; Niwa, Osamu; Tokito, Shizuo

    2016-07-15

    First selective nitrate biosensor device based on an extended-gate type organic field-effect transistor (OFET) is reported. The fabricated sensor device consists of the extended-gate electrode functionalized by a nitrate reductase with a mediator (=a bipyridinium derivative) and an OFET-based transducer. The mechanism of the nitrate detection can be explained by an electron-relay on the extended-gate electrode, resulting in changes of the electric properties of the OFET. The detection limit of nitrate in water is estimated to be 45 ppb, which suggests that the sensitivity of our fabricated sensor is comparable to those of some conventional detection methods. As a practical application of the OFET sensor, the nitrate detection in diluted human saliva has been successfully demonstrated; the results agreed well with those by conventional colorimetric measurement. The advantages of OFETs are printability, mechanical flexibility, stretchability and disposability, meaning that the fabricated OFET could open up a new approach for low-cost electronic devices toward on-site detection of nitrate in aqueous media.

  4. Radiation from Relativistic Jets in Turbulent Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Mizuno, Y.; Medvedev, M.; Zhang, B.; Hardee, P.; Niemiec, J.; Nordlund, A.; Frederiksen, J.; Mizuno, Y.; Sol, H.; Fishman, G. J.

    2008-01-01

    Using our new 3-D relativistic electromagnetic particle (REMP) code parallelized with MPI, we have investigated long-term particle acceleration associated with an relativistic electron-positron jet propagating in an unmagnetized ambient electron-positron plasma. The simulations have been performed using a much longer simulation system than our previous simulations in order to investigate the full nonlinear stage of the Weibel instability and its particle acceleration mechanism. Cold jet electrons are thermalized and ambient electrons are accelerated in the resulting shocks. The acceleration of ambient electrons leads to a maximum ambient electron density three times larger than the original value. Behind the bow shock in the jet shock strong electromagnetic fields are generated. These fields may lead to the afterglow emission. We have calculated the time evolution of the spectrum from two electrons propagating in a uniform parallel magnetic field to verify the technique.

  5. BOBCAT Personal Radiation Detector Field Test and Evaluation Campaign

    SciTech Connect

    Chris Hodge

    2008-03-01

    Following the success of the Anole test of portable detection system, the U.S. Department of Homeland Security (DHS) Domestic Nuclear Detection Office organized a test and evaluation campaign for personal radiation detectors (PRDs), also known as “Pagers.” This test, “Bobcat,” was conducted from July 17 to August 8, 2006, at the Nevada Test Site. The Bobcat test was designed to evaluate the performance of PRDs under various operational scenarios, such as pedestrian surveying, mobile surveying, cargo container screening, and pedestrian chokepoint monitoring. Under these testing scenarios, many operational characteristics of the PRDs, such as gamma and neutron sensitivities, positive detection and false alarm rates, response delay times, minimum detectable activities, and source localization errors, were analyzed. This paper will present the design, execution, and methodologies used to test this equipment for the DHS.

  6. Personal Radiation Detector Field Test and Evaluation Campaign

    SciTech Connect

    Chris A. Hodge, Ding Yuan, Raymond P. Keegan, Michael A. Krstich

    2007-07-09

    Following the success of the Anole test of portable detection system, the U.S. Department of Homeland Security (DHS) Domestic Nuclear Detection Office organized a test and evaluation campaign for personal radiation detectors (PRDs), also known as 'Pagers'. This test, 'Bobcat', was conducted from July 17 to August 8, 2006, at the Nevada Test Site. The Bobcat test was designed to evaluate the performance of PRDs under various operational scenarios, such as pedestrian surveying, mobile surveying, cargo container screening, and pedestrian chokepoint monitoring. Under these testing scenarios, many operational characteristics of the PRDs, such as gamma and neutron sensitivities, positive detection and false alarm rates, response delay times, minimum detectable activities, and source localization errors, were analyzed. This paper will present the design, execution, and methodologies used to test this equipment for the DHS.

  7. Near Field Radiation Characteristics of Implantable Square Spiral Chip Inductor Antennas for Bio-Sensors

    NASA Technical Reports Server (NTRS)

    Nessel, James A.; Simons, Rainee N.; Miranda, Felix A.

    2007-01-01

    The near field radiation characteristics of implantable Square Spiral Chip Inductor Antennas (SSCIA) for Bio-Sensors have been measured. Our results indicate that the measured near field relative signal strength of these antennas agrees with simulated results and confirm that in the near field region the radiation field is fairly uniform in all directions. The effects of parameters such as ground-plane, number of turns and microstrip-gap width on the performance of the SSCIA are presented. Furthermore, the SSCIA antenna with serrated ground plane produce a broad radiation pattern, with a relative signal strength detectable at distances within the range of operation of hand-held devices for self-diagnosis.

  8. Simulation of Relativistic Shocks and Associated Radiation from Turbulent Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Mizuno, Y.; Niemiec, J.; Medvedev, M.; Zhang, B.; Hardee, P.; Frederiksen, J.; Sol, H.; Pohl, M.; Hartmann, D. H.; Fishman, G. J.

    2010-01-01

    Recent PIC simulations of relativistic electron-positron (electron-ion) jets injected into a stationary medium show that particle acceleration occurs at shocked regions. Simulations show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields and particle acceleration. These magnetic fields contribute to the electron's transverse deflection behind the shock. The jitter'' radiation from deflected electrons in turbulent magnetic fields has different properties than synchrotron radiation, which is calculated in a uniform magnetic field. This jitter radiation may be important for understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets in general, and supernova remnants. We will present detailed spectra for conditions relevant of various astrophysical sites of shock formation via the Weibel instability. In particular we will discuss the application to GRBs and SNRs

  9. Effects of radiation damping on particle motion in pulsar vacuum fields

    NASA Astrophysics Data System (ADS)

    Finkbeiner, B.; Herold, H.; Ertl, T.; Ruder, H.

    1989-11-01

    The effects of radiation reaction on the motion of charged particles are studied in strong electric and magnetic fields with special attention to the vacuum near-field region of an oblique rotator. For strong radiation damping a local velocity field is derived from the Lorentz-Dirac equation, which efficiently describes the motion of electrons and positrons in the whole range of typical pulsar parameters. The velocity field makes it possible to define regions in the inner magnetosphere, where particle trapping occurs due to the radiation losses. By numerical integration of particle trajectories from the pulsar surface, regions around the magnetic poles are found which are defined by particle emission into the wave zone. The shapes of the escape regions on the pulsar surface are determined to a considerable extent by the presence of the accumulation regions.

  10. Micro Penning Trap for Continuous Magnetic Field Monitoring in High Radiation Environments

    NASA Astrophysics Data System (ADS)

    Latorre, Javiera; Bollen, Georg; Gulyuz, Kerim; Ringle, Ryan; Bado, Philippe; Dugan, Mark; Lebit Team; Translume Collaboration

    2016-09-01

    As new facilities for rare isotope beams, like FRIB at MSU, are constructed, there is a need for new instrumentation to monitor magnetic fields in beam magnets that can withstand the higher radiation level. Currently NMR probes, the instruments used extensively to monitor magnetic fields, do not have a long lifespans in radiation-high environments. Therefore, a radiation-hard replacement is needed. We propose to use Penning trap mass spectrometry techniques to make high precision magnetic field measurements. Our Penning microtrap will be radiation resistant as all of the vital electronics will be at a safe distance from the radiation. The trap itself is made from materials not subject to radiation damage. Penning trap mass spectrometers can determine the magnetic field by measuring the cyclotron frequency of an ion with a known mass and charge. This principle is used on the Low Energy Beam Ion Trap (LEBIT) minitrap at NSCL which is the foundation for the microtrap. We have partnered with Translume, who specialize in glass micro-fabrication, to develop a microtrap in fused-silica glass. A microtrap is finished and ready for testing at NSCL with all of the electronic and hardware components setup. DOE Phase II SBIR Award No. DE-SC0011313, NSF Award Number 1062410 REU in Physics, NSF under Grant No. PHY-1102511.

  11. Extended particle-in-cell schemes for physics in ultrastrong laser fields: Review and developments.

    PubMed

    Gonoskov, A; Bastrakov, S; Efimenko, E; Ilderton, A; Marklund, M; Meyerov, I; Muraviev, A; Sergeev, A; Surmin, I; Wallin, E

    2015-08-01

    We review common extensions of particle-in-cell (PIC) schemes which account for strong field phenomena in laser-plasma interactions. After describing the physical processes of interest and their numerical implementation, we provide solutions for several associated methodological and algorithmic problems. We propose a modified event generator that precisely models the entire spectrum of incoherent particle emission without any low-energy cutoff, and which imposes close to the weakest possible demands on the numerical time step. Based on this, we also develop an adaptive event generator that subdivides the time step for locally resolving QED events, allowing for efficient simulation of cascades. Further, we present a unified technical interface for including the processes of interest in different PIC implementations. Two PIC codes which support this interface, PICADOR and ELMIS, are also briefly reviewed.

  12. Extended particle-in-cell schemes for physics in ultrastrong laser fields: Review and developments

    NASA Astrophysics Data System (ADS)

    Gonoskov, A.; Bastrakov, S.; Efimenko, E.; Ilderton, A.; Marklund, M.; Meyerov, I.; Muraviev, A.; Sergeev, A.; Surmin, I.; Wallin, E.

    2015-08-01

    We review common extensions of particle-in-cell (PIC) schemes which account for strong field phenomena in laser-plasma interactions. After describing the physical processes of interest and their numerical implementation, we provide solutions for several associated methodological and algorithmic problems. We propose a modified event generator that precisely models the entire spectrum of incoherent particle emission without any low-energy cutoff, and which imposes close to the weakest possible demands on the numerical time step. Based on this, we also develop an adaptive event generator that subdivides the time step for locally resolving QED events, allowing for efficient simulation of cascades. Further, we present a unified technical interface for including the processes of interest in different PIC implementations. Two PIC codes which support this interface, picador and elmis, are also briefly reviewed.

  13. New correction procedures for the fast field program which extend its range

    NASA Technical Reports Server (NTRS)

    West, M.; Sack, R. A.

    1990-01-01

    A fast field program (FFP) algorithm was developed based on the method of Lee et al., for the prediction of sound pressure level from low frequency, high intensity sources. In order to permit accurate predictions at distances greater than 2 km, new correction procedures have had to be included in the algorithm. Certain functions, whose Hankel transforms can be determined analytically, are subtracted from the depth dependent Green's function. The distance response is then obtained as the sum of these transforms and the Fast Fourier Transformation (FFT) of the residual k dependent function. One procedure, which permits the elimination of most complex exponentials, has allowed significant changes in the structure of the FFP algorithm, which has resulted in a substantial reduction in computation time.

  14. Extended field observations of cirrus clouds using a ground-based cloud observing system

    NASA Technical Reports Server (NTRS)

    Ackerman, Thomas P.

    1994-01-01

    The evolution of synoptic-scale dynamics associated with a middle and upper tropospheric cloud event that occurred on 26 November 1991 is examined. The case under consideration occurred during the FIRE CIRRUS-II Intensive Field Observing Period held in Coffeyville, KS during Nov. and Dec., 1991. Using data from the wind profiler demonstration network and a temporally and spatially augmented radiosonde array, emphasis is given to explaining the evolution of the kinematically-derived ageostrophic vertical circulations and correlating the circulation with the forcing of an extensively sampled cloud field. This is facilitated by decomposing the horizontal divergence into its component parts through a natural coordinate representation of the flow. Ageostrophic vertical circulations are inferred and compared to the circulation forcing arising from geostrophic confluence and shearing deformation derived from the Sawyer-Eliassen Equation. It is found that a thermodynamically indirect vertical circulation existed in association with a jet streak exit region. The circulation was displaced to the cyclonic side of the jet axis due to the orientation of the jet exit between a deepening diffluent trough and building ridge. The cloud line formed in the ascending branch of the vertical circulation with the most concentrated cloud development occurring in conjunction with the maximum large-scale vertical motion. The relationship between the large scale dynamics and the parameterization of middle and upper tropospheric clouds in large-scale models is discussed and an example of ice water contents derived from a parameterization forced by the diagnosed vertical motions and observed water vapor contents is presented.

  15. SU-F-207-09: Evaluating the Dosimetric Accuracy of Extended Field-Of-View CT Reconstructions Using Clinical Data with Real Patient Geometries

    SciTech Connect

    Shugard, E; Cheung, J; Pouliot, J; Chen, J; Mistry, N

    2015-06-15

    Purpose: To determine the accuracy of dose calculations performed with CT images reconstructed using extended field of view (FOV) algorithms. Methods: In this study we selected 6 radiotherapy patients (3 head and neck & 3 chest/pelvis) whose body circumferences extended past the 50 cm scan FOV in the treatment planning CT. Images acquired on a Siemens Sensation Open scanner, were reconstructed using the standard FOV (sFOV) and two different extended FOV algorithms, eFOV and HDFOV. A physician and dosimetrist identified the radiation target, critical organs, and external patient contour. A benchmark CT was created for each patient, consisting of an average of the 3 CT reconstructions with a density override applied to regions containing truncation artifacts, and was used to create an optimal radiation treatment plan. The plan was copied onto each reconstruction without density override and dose was recalculated. Results: The native sFOV dose calculations had the largest deviation from the benchmark (0.4 – 6.0%). Both the HDFOV and eFOV calculations showed improvement over the sFOV. For patients with a smooth patient contour, the HDFOV calculation had the least deviation from the benchmark (0.1–0.5%) compared to eFOV (0.4–1.8%). In cases with large amounts of tissue and irregular skin folds, the eFOV deviated the least from the benchmark (0.2–0.6%) compared to HDFOV (1.3–1.8%). It was observed that the eFOV scan has large image artifact in air with an average HU of −600 compared to the ideal of −1000. In these cases, the artifact in air appears to attenuate the dose and compensate for the missing tissue density. The HDFOV demonstrated minimal artifact in air. Conclusion: Both eFOV and HDFOV provide improved dose calculation accuracy. The HDFOV reconstruction provides a clearer patient border than the eFOV allowing for well-defined density overrides to be applied with minimal air artifact. This research was supported by Siemens Medical Solutions.

  16. Extended field-of-view and increased-signal 3D holographic illumination with time-division multiplexing.

    PubMed

    Yang, Samuel J; Allen, William E; Kauvar, Isaac; Andalman, Aaron S; Young, Noah P; Kim, Christina K; Marshel, James H; Wetzstein, Gordon; Deisseroth, Karl

    2015-12-14

    Phase spatial light modulators (SLMs) are widely used for generating multifocal three-dimensional (3D) illumination patterns, but these are limited to a field of view constrained by the pixel count or size of the SLM. Further, with two-photon SLM-based excitation, increasing the number of focal spots penalizes the total signal linearly--requiring more laser power than is available or can be tolerated by the sample. Here we analyze and demonstrate a method of using galvanometer mirrors to time-sequentially reposition multiple 3D holograms, both extending the field of view and increasing the total time-averaged two-photon signal. We apply our approach to 3D two-photon in vivo neuronal calcium imaging.

  17. Extended field-of-view and increased-signal 3D holographic illumination with time-division multiplexing

    PubMed Central

    Yang, Samuel J.; Allen, William E.; Kauvar, Isaac; Andalman, Aaron S.; Young, Noah P.; Kim, Christina K.; Marshel, James H.; Wetzstein, Gordon; Deisseroth, Karl

    2016-01-01

    Phase spatial light modulators (SLMs) are widely used for generating multifocal three-dimensional (3D) illumination patterns, but these are limited to a field of view constrained by the pixel count or size of the SLM. Further, with two-photon SLM-based excitation, increasing the number of focal spots penalizes the total signal linearly—requiring more laser power than is available or can be tolerated by the sample. Here we analyze and demonstrate a method of using galvanometer mirrors to time-sequentially reposition multiple 3D holograms, both extending the field of view and increasing the total time-averaged two-photon signal. We apply our approach to 3D two-photon in vivo neuronal calcium imaging. PMID:26699047

  18. High Sensitivity pH Sensor Based on Porous Silicon (PSi) Extended Gate Field-Effect Transistor

    PubMed Central

    Al-Hardan, Naif H.; Abdul Hamid, Muhammad Azmi; Ahmed, Naser M.; Jalar, Azman; Shamsudin, Roslinda; Othman, Norinsan Kamil; Kar Keng, Lim; Chiu, Weesiong; Al-Rawi, Hamzah N.

    2016-01-01

    In this study, porous silicon (PSi) was prepared and tested as an extended gate field-effect transistor (EGFET) for pH sensing. The prepared PSi has pore sizes in the range of 500 to 750 nm with a depth of approximately 42 µm. The results of testing PSi for hydrogen ion sensing in different pH buffer solutions reveal that the PSi has a sensitivity value of 66 mV/pH that is considered a super Nernstian value. The sensor considers stability to be in the pH range of 2 to 12. The hysteresis values of the prepared PSi sensor were approximately 8.2 and 10.5 mV in the low and high pH loop, respectively. The result of this study reveals a promising application of PSi in the field for detecting hydrogen ions in different solutions. PMID:27338381

  19. A Numerical Treatment of Anisotropic Radiation Fields Coupled with Relativistic Resistive Magnetofluids

    NASA Astrophysics Data System (ADS)

    Takahashi, Hiroyuki R.; Ohsuga, Ken

    2013-08-01

    We develop a numerical scheme for solving fully special relativistic, resistive radiation magnetohydrodynamics. Our code guarantees conservation of total mass, momentum, and energy. The radiation energy density and the radiation flux are consistently updated using the M-1 closure method, which can resolve an anisotropic radiation field, in contrast to the Eddington approximation, as well as the flux-limited diffusion approximation. For the resistive part, we adopt a simple form of Ohm's law. The advection terms are explicitly solved with an approximate Riemann solver, mainly the Harten-Lax-van Leer scheme; the HLLC and HLLD schemes are also solved for some tests. The source terms, which describe the gas-radiation interaction and the magnetic energy dissipation, are implicitly integrated, relaxing the Courant-Friedrichs-Lewy condition even in an optically thick regime or a large magnetic Reynolds number regime. Although we need to invert 4 × 4 matrices (for the gas-radiation interaction) and 3 × 3 matrices (for the magnetic energy dissipation) at each grid point for implicit integration, they are obtained analytically without preventing massive parallel computing. We show that our code gives reasonable outcomes in numerical tests for ideal magnetohydrodynamics, propagating radiation, and radiation hydrodynamics. We also applied our resistive code to the relativistic Petschek-type magnetic reconnection, revealing the reduction of the reconnection rate via radiation drag.

  20. A NUMERICAL TREATMENT OF ANISOTROPIC RADIATION FIELDS COUPLED WITH RELATIVISTIC RESISTIVE MAGNETOFLUIDS

    SciTech Connect

    Takahashi, Hiroyuki R.; Ohsuga, Ken

    2013-08-01

    We develop a numerical scheme for solving fully special relativistic, resistive radiation magnetohydrodynamics. Our code guarantees conservation of total mass, momentum, and energy. The radiation energy density and the radiation flux are consistently updated using the M-1 closure method, which can resolve an anisotropic radiation field, in contrast to the Eddington approximation, as well as the flux-limited diffusion approximation. For the resistive part, we adopt a simple form of Ohm's law. The advection terms are explicitly solved with an approximate Riemann solver, mainly the Harten-Lax-van Leer scheme; the HLLC and HLLD schemes are also solved for some tests. The source terms, which describe the gas-radiation interaction and the magnetic energy dissipation, are implicitly integrated, relaxing the Courant-Friedrichs-Lewy condition even in an optically thick regime or a large magnetic Reynolds number regime. Although we need to invert 4 Multiplication-Sign 4 matrices (for the gas-radiation interaction) and 3 Multiplication-Sign 3 matrices (for the magnetic energy dissipation) at each grid point for implicit integration, they are obtained analytically without preventing massive parallel computing. We show that our code gives reasonable outcomes in numerical tests for ideal magnetohydrodynamics, propagating radiation, and radiation hydrodynamics. We also applied our resistive code to the relativistic Petschek-type magnetic reconnection, revealing the reduction of the reconnection rate via radiation drag.

  1. High field CdS detector for infrared radiation

    NASA Technical Reports Server (NTRS)

    Tyagi, R. C.; Boer, K. W.; Hadley, H. C.; Robertson, J. B.

    1972-01-01

    New and highly sensitive method of detecting infrared irradiation makes possible solid state infrared detector which is more sensitive near room temperature than usual photoconductive low band gap semiconductor devices. Reconfiguration of high field domains in cadmium sulphide crystals provides basis for discovery.

  2. An extended version of Boyd's force field method applicable to heteroatomic molecules. Part 1. Adenine and uracil

    NASA Astrophysics Data System (ADS)

    Espinosa-Müller, A. W.; Bravo, A. N.

    The force field method developed by Boyd is extended to include molecules containing atoms other than C and H (e.g., N, O, P, S, Cl, Br,…). A new set of force field parameters is determined in order to redefine the potential energy functions that govern the dynamics of the internal (valence coordinates) degrees of freedom of a molecule. It is shown that the minimum of the partial potential energy surface is significantly affected by electrostatic intramolecular interactions. In this regard the non-bonded interactions appears to be less important than the dipole-dipole type interactions for a given interatomic distance when heteroatoms are present in the molecular framework. The reliability of the extended method as regards minimized structure, vibrational spectra and thermodynamic properties has been checked for more than 20 polyatomic molecules. From the correlation between calculated and experimental properties it is concluded that the method has good potential for further applications on polyatomic molecules with increasing size and topological compexities such as adenine and uracil.

  3. Extending the field of play: Revealing the dynamics between sports, health and place.

    PubMed

    Andrews, Gavin J

    2016-11-01

    Although the sub-discipline of sports geography has a long fifty-year history it has been, at best, a sporadic endeavor. Whilst clearly indicating the fundamental geographical qualities of sports, it has never really taking off to the extent that arguably it should have given sport's social profile and importance. In way of a solution this paper presents triple tracks, or ways forward, that might circumvent this academic shortfall and cover some of the missed ground. First, pursuing the health component of sport far more thoroughly and in its very broadest sense, including its public health adoption and specific wellbeing, fitness and aesthetic features. Second, defining sport broadly beyond elite forms to include a wide-range of physical and lifestyle activities that possess elements of personal or interpersonal competition. Third, complementing sports geography by developing 'spatial sports studies' as a more expansive interdisciplinary field of inquiry spanning the health and social sciences. Indeed, these tracks potentially unearth substantial new research capacity by together considering the dynamics between sports, health and place.

  4. A Study of High Altitude Hypersonic Flow-Field Radiation

    NASA Technical Reports Server (NTRS)

    Moreau, Stephane; Park, Chul; Edwards, Thomas A. (Technical Monitor)

    1994-01-01

    This paper presents the results of the works carried out jointly at Stanford University and Ames Research Center under a grant from the Ballistic Missile Defense Organization (BMDO) (formerly the Strategic Defense Initiative Organization) to explain and understand the results of the two flight experiments, Bow Shock Ultra-Violet 1 and Bow Shock Ultra-Violet 2, carried out by the Organization. A portion of the material contained in this paper has been reported elsewhere in open literature. However, this paper provides (1) the details of scientific contents not available in those literature, (2) the links among those and the logical order of the efforts involved, and (3) some materials not contained in any open literature. The first author is responsible for execution of the work; the second author directed the work of the first author. In the two flight experiments mentioned above, the spectra of radiation in the ultraviolet wavelength range incident on the stagnation point of a blunt body were measured at the flight speeds of 3.8 and 5.2 km/sec over a wide range of altitudes. The results were compared first with the calculations made using the original version of the NEQAIR/STRAP codes written earlier by the second author. At low altitudes, the calculations agreed with the measurement. However, at high altitudes, the calculations underestimated the intensity of the radiation by several orders of magnitudes. A shock tube experiment was carried out at CALSPAN and a plasma-torch experiment was carried out at Stanford University to produce experimental data to help explain the discrepancy. In addition, the shock tube experiment at Ames Research Center carried out independently of the BMDO was also found to be relevant to this question. In this paper, several theoretical models are developed and calculations using the models were carried out to explain the results not only of the flight experiments but also of the CALSPAN, Stanford, and Ames experiments. The are: (1

  5. Characterization of Radiation Fields in Biological Shields of Nuclear Power Plants for Assessing Concrete Degradation

    SciTech Connect

    Remec, Igor; Rosseel, Thomas M; Field, Kevin G; Pape, Yann Le

    2016-01-01

    Life extensions of nuclear power plants to 60 and potentially 80 years of operation have renewed interest in long-term material degradation. One material being considered is concrete with a particular focus on radiation-induced effects. Based on the projected neutron fluence (E > 0.1 MeV) values in the concrete biological shields of the US PWR fleet and the available data on radiation effects on concrete, some decrease in mechanical properties of concrete cannot be ruled out during extended operation beyond 60 years. An expansion of the irradiated concrete database and a reliable determination of relevant neutron fluence energy cutoff value are necessary to assure reliable risk assessment for NPPs extended operation.

  6. Field size dependent mapping of medical linear accelerator radiation leakage

    NASA Astrophysics Data System (ADS)

    Vũ Bezin, Jérémi; Veres, Attila; Lefkopoulos, Dimitri; Chavaudra, Jean; Deutsch, Eric; de Vathaire, Florent; Diallo, Ibrahima

    2015-03-01

    The purpose of this study was to investigate the suitability of a graphics library based model for the assessment of linear accelerator radiation leakage. Transmission through the shielding elements was evaluated using the build-up factor corrected exponential attenuation law and the contribution from the electron guide was estimated using the approximation of a linear isotropic radioactive source. Model parameters were estimated by a fitting series of thermoluminescent dosimeter leakage measurements, achieved up to 100 cm from the beam central axis along three directions. The distribution of leakage data at the patient plane reflected the architecture of the shielding elements. Thus, the maximum leakage dose was found under the collimator when only one jaw shielded the primary beam and was about 0.08% of the dose at isocentre. Overall, we observe that the main contributor to leakage dose according to our model was the electron beam guide. Concerning the discrepancies between the measurements used to calibrate the model and the calculations from the model, the average difference was about 7%. Finally, graphics library modelling is a readily and suitable way to estimate leakage dose distribution on a personal computer. Such data could be useful for dosimetric evaluations in late effect studies.

  7. TOPICAL REVIEW: Asymptotic directional structure of radiative fields in spacetimes with a cosmological constant

    NASA Astrophysics Data System (ADS)

    Krtous, Pavel; Podolský, Jirí

    2004-12-01

    We analyse the directional properties of general gravitational, electromagnetic and spin-s fields near conformal infinity \\scri . The fields are evaluated in normalized tetrads which are parallelly propagated along null geodesics which approach a point P of \\scri . The standard peeling-off property is recovered and its meaning is discussed and refined. When the (local) character of the conformal infinity is null, such as in asymptotically flat spacetimes, the dominant term which is identified with radiation is unique. However, for spacetimes with a non-vanishing cosmological constant the conformal infinity is spacelike (for Λ > 0) or timelike (for Λ < 0), and the radiative component of each field depends substantially on the null direction along which P is approached. The directional dependence of asymptotic fields near such de Sitter-like or anti-de Sitter-like \\scri is explicitly found and described. We demonstrate that the corresponding directional structure of radiation has a universal character that is determined by the algebraic (Petrov) type of the field. In particular, when Λ > 0 the radiation vanishes only along directions which are opposite to principal null directions. For Λ < 0 the directional dependence is more complicated because it is necessary to distinguish outgoing and ingoing radiation. Near such anti-de Sitter-like conformal infinity the corresponding directional structures differ, depending not only on the number and degeneracy of the principal null directions at P but also on their specific orientation with respect to \\scri . The directional structure of radiation near (anti-)de Sitter-like infinities supplements the standard peeling-off property of spin-s fields. This characterization offers a better understanding of the asymptotic behaviour of the fields near conformal infinity under the presence of a cosmological constant.

  8. Radiation magnetohydrodynamic simulation of plasma formed on a surface by a megagauss field.

    PubMed

    Esaulov, A A; Bauer, B S; Makhin, V; Siemon, R E; Lindemuth, I R; Awe, T J; Reinovsky, R E; Struve, K W; Desjarlais, M P; Mehlhorn, T A

    2008-03-01

    Radiation magnetohydrodynamic modeling is used to study the plasma formed on the surface of a cylindrical metallic load, driven by megagauss magnetic field at the 1MA Zebra generator (University of Nevada, Reno). An ionized aluminum plasma is used to represent the "core-corona" behavior in which a heterogeneous Z-pinch consists of a hot low-density corona surrounding a dense low-temperature core. The radiation dynamics model included simultaneously a self-consistent treatment of both the opaque and transparent plasma regions in a corona. For the parameters of this experiment, the boundary of the opaque plasma region emits the major radiation power with Planckian black-body spectrum in the extreme ultraviolet corresponding to an equilibrium temperature of 16 eV. The radiation heat transport significantly exceeds the electron and ion kinetic heat transport in the outer layers of the opaque plasma. Electromagnetic field energy is partly radiated (13%) and partly deposited into inner corona and core regions (87%). Surface temperature estimates are sensitive to the radiation effects, but the surface motion in response to pressure and magnetic forces is not. The general results of the present investigation are applicable to the liner compression experiments at multi-MA long-pulse current accelerators such as Atlas and Shiva Star. Also the radiation magnetohydrodynamic model discussed in the paper may be useful for understanding key effects of wire array implosion dynamics.

  9. Effective Count-Rates for PET Scanners with Reduced and Extended Axial Field of View

    PubMed Central

    MacDonald, LR; Harrison, RL; Alessio, AM; Hunter, WCJ; Lewellen, TK; Kinahan, PE

    2011-01-01

    We investigated the relationship between noise equivalent counts (NEC) and axial field of view (AFOV) for PET scanners with AFOVs ranging from one-half to twice those of current clinical scanners. PET scanners with longer or shorter AFOVs could fulfill different clinical needs depending on exam volumes and site economics. Using previously validated Monte Carlo simulations, we modeled true, scattered, and random coincidence counting rates for a PET ring diameter of 88 cm with 2, 4, 6, and 8 rings of detector blocks (AFOV 7.8, 15.5, 23.3, and 31.0 cm). Fully 3D acquisition mode was compared to full collimation (2D) and partial collimation (2.5D) modes. Counting rates were estimated for a 200 cm long version of the 20 cm diameter NEMA countrate phantom and for an anthropomorphic object based on a patient scan. We estimated the live-time characteristics of the scanner from measured count-rate data and applied that estimate to the simulated results to obtain NEC as a function of object activity. We found NEC increased as a quadratic function of AFOV for 3D mode, and linearly in 2D mode. Partial collimation provided the highest overall NEC on the 2-block system and fully 3D mode provided the highest NEC on the 8-block system for clinically relevant activities. On the 4-, and 6-block systems 3D mode NEC was highest up to ~300 MBq in the anthropomorphic phantom, above which 3D NEC dropped rapidly, and 2.5D NEC was highest. Projected total scan time to achieve NEC-density that matches current clinical practice in a typical oncology exam averaged 9, 15, 24, and 61 min for the 8-, 6-, 4-, and 2-block ring systems, when using optimal collimation. Increasing the AFOV should provide a greater than proportional increase in NEC, potentially benefiting patient throughput-to-cost ratio. Conversely, by using appropriate collimation, a two-ring (7.8 cm AFOV) system could acquire whole-body scans achieving NEC-density levels comparable to current standards within long, but feasible

  10. TSUBASA (MDS-1) observations of energetic electrons and magnetic field variations in outer radiation belt

    NASA Astrophysics Data System (ADS)

    Nakamura, M.; Matsuoka, H.; Liu, H.; Koshiishi, H.; Koga, K.; Matsumoto, H.; Goka, T.

    2002-12-01

    We have investigated variations of energetic electrons (> 0.4 MeV) and magnetic field in the radiation belt obtained from the Standard DOse Monitor (SDOM) and the MAgnetoMeter (MAM) of the Space Environment Data Acquisition equipment (SEDA) onboard TSUBASA (the Mission Demonstration Test Satellite (MDS)-1) launched on February 4, 2002. Since TSUBASA is operated in the geostationary transfer orbit, it has provided rare opportunities of directly observing near-equatorial radiation belt plasma particles and magnetic field, having already included several large magnetic storms. The energetic electrons in the outer radiation belt are contributors to the total radiation dose deposited in lightly shielded spacecraft electronics for high altitude orbits and are known to have a drastic variability associated with geomagnetic storm and high speed solar wind streams. The abrupt energetic electron flux decreases in the outside of outer radiation belt show characteristic variations of in situ magnetic field. These observations have implications for the possible mechanisms of the depletion and the following recovery and/or buildup of energetic electrons in the outer radiation belt.

  11. Nuclear forward scattering of synchrotron radiation in pulsed high magnetic fields.

    PubMed

    Strohm, C; Van der Linden, P; Rüffer, R

    2010-02-26

    We report the demonstration of nuclear forward scattering of synchrotron radiation from 57Fe in ferromagnetic alpha iron in pulsed high magnetic fields up to 30 T. The observed magnetic hyperfine field follows the calculated high field bulk magnetization within 1%, establishing the technique as a precise tool for the study of magnetic solids in very high magnetic fields. To perform these experiments in pulsed fields, we have developed a detection scheme for fully time resolved nuclear forward scattering applicable to other pump probe experiments.

  12. Measurement of the neutron fields produced by a 62 MeV proton beam on a PMMA phantom using extended range Bonner sphere spectrometers

    NASA Astrophysics Data System (ADS)

    Amgarou, K.; Bedogni, R.; Domingo, C.; Esposito, A.; Gentile, A.; Carinci, G.; Russo, S.

    2011-10-01

    The experimental characterization of the neutron fields produced as parasitic effect in medical accelerators is assuming an increased importance for either the patient protection or the facility design aspects. Medical accelerators are diverse in terms of particle type (electrons or hadrons) and energy, but the radiation fields around them have in common (provided that a given threshold energy is reached) the presence of neutrons with energy span over several orders of magnitude. Due to the large variability of neutron energy, field or dosimetry measurements in these workplaces are very complex, and in general, cannot be performed with ready-to-use commercial instruments. In spite of its poor energy resolution, the Bonner Sphere Spectrometer (BSS) is the only instrument able to simultaneously determine all spectral components in such workplaces. The energy range of this instrument is limited to E<20 MeV if only polyethylene spheres are used, but can be extended to hundreds of MeV by including metal-loaded spheres (extended range BSS, indicated with ERBSS). With the aim of providing useful data to the scientific community involved in neutron measurements at hadron therapy facilities, an ERBSS experiment was carried out at the Centro di AdroTerapia e Applicazioni Nucleari Avanzate (CATANA) of INFN—LNS (Laboratori Nazionali del Sud), where a proton beam routinely used for ophthalmic cancer treatments is available. The 62 MeV beam was directed towards a PMMA phantom, simulating the patient, and two neutron measurement points were established at 0° and 90° with respect to the beam-line. Here the ERBSS of UAB (Universidad Autónoma de Barcelona— Grup de Física de les Radiacions) and INFN (Istituto Nazionale di Fisica Nucleare—Laboratori Nazionali di Frascati) were exposed to characterize the "forward" and "sideward" proton-induced neutron fields. The use of two ERBSS characterized by different set of spheres, central detectors, and independently established and

  13. Entanglement and nonclassicality for multimode radiation-field states

    SciTech Connect

    Ivan, J. Solomon; Chaturvedi, S.; Ercolessi, E.; Marmo, G.; Morandi, G.; Mukunda, N.; Simon, R.

    2011-03-15

    Nonclassicality in the sense of quantum optics is a prerequisite for entanglement in multimode radiation states. In this work we bring out the possibilities of passing from the former to the latter, via action of classicality preserving systems like beam splitters, in a transparent manner. For single-mode states, a complete description of nonclassicality is available via the classical theory of moments, as a set of necessary and sufficient conditions on the photon number distribution. We show that when the mode is coupled to an ancilla in any coherent state, and the system is then acted upon by a beam splitter, these conditions turn exactly into signatures of negativity under partial transpose (NPT) entanglement of the output state. Since the classical moment problem does not generalize to two or more modes, we turn in these cases to other familiar sufficient but not necessary conditions for nonclassicality, namely the Mandel parameter criterion and its extensions. We generalize the Mandel matrix from one-mode states to the two-mode situation, leading to a natural classification of states with varying levels of nonclassicality. For two-mode states we present a single test that can, if successful, simultaneously show nonclassicality as well as NPT entanglement. We also develop a test for NPT entanglement after beam-splitter action on a nonclassical state, tracing carefully the way in which it goes beyond the Mandel nonclassicality test. The result of three-mode beam-splitter action after coupling to an ancilla in the ground state is treated in the same spirit. The concept of genuine tripartite entanglement, and scalar measures of nonclassicality at the Mandel level for two-mode systems, are discussed. Numerous examples illustrating all these concepts are presented.

  14. Technical Note: Response measurement for select radiation detectors in magnetic fields

    SciTech Connect

    Reynolds, M.; Fallone, B. G.; Rathee, S.

    2015-06-15

    Purpose: Dose response to applied magnetic fields for ion chambers and solid state detectors has been investigated previously for the anticipated use in linear accelerator–magnetic resonance devices. In this investigation, the authors present the measured response of selected radiation detectors when the magnetic field is applied in the same direction as the radiation beam, i.e., a longitudinal magnetic field, to verify previous simulation only data. Methods: The dose response of a PR06C ion chamber, PTW60003 diamond detector, and IBA PFD diode detector is measured in a longitudinal magnetic field. The detectors are irradiated with buildup caps and their long axes either parallel or perpendicular to the incident photon beam. In each case, the magnetic field dose response is reported as the ratio of detector signals with to that without an applied longitudinal magnetic field. The magnetic field dose response for each unique orientation as a function of magnetic field strength was then compared to the previous simulation only studies. Results: The measured dose response of each detector in longitudinal magnetic fields shows no discernable response up to near 0.21 T. This result was expected and matches the previously published simulation only results, showing no appreciable dose response with magnetic field. Conclusions: Low field longitudinal magnetic fields have been shown to have little or no effect on the dose response of the detectors investigated and further lend credibility to previous simulation only studies.

  15. Simulation studies of wide and medium field of view earth radiation data analysis

    NASA Technical Reports Server (NTRS)

    Green, R. N.

    1978-01-01

    A parameter estimation technique is presented to estimate the radiative flux distribution over the earth from radiometer measurements at satellite altitude. The technique analyzes measurements from a wide field of view (WFOV), horizon to horizon, nadir pointing sensor with a mathematical technique to derive the radiative flux estimates at the top of the atmosphere for resolution elements smaller than the sensor field of view. A computer simulation of the data analysis technique is presented for both earth-emitted and reflected radiation. Zonal resolutions are considered as well as the global integration of plane flux. An estimate of the equator-to-pole gradient is obtained from the zonal estimates. Sensitivity studies of the derived flux distribution to directional model errors are also presented. In addition to the WFOV results, medium field of view results are presented.

  16. Electromagnetic fields radiated from a lightning return stroke - Application of an exact solution to Maxwell's equations

    NASA Technical Reports Server (NTRS)

    Le Vine, D. M.; Meneghini, R.

    1978-01-01

    A solution is presented for the electromagnetic fields radiated by an arbitrarily oriented current filament over a conducting ground plane in the case where the current propagates along the filament at the speed of light, and this solution is interpreted in terms of radiation from lightning return strokes. The solution is exact in the fullest sense; no mathematical approximations are made, and the governing differential equations and boundary conditions are satisfied. The solution has the additional attribute of being specified in closed form in terms of elementary functions. This solution is discussed from the point of view of deducing lightning current wave forms from measurements of the electromagnetic fields and understanding the effects of channel tortuosity on the radiated fields. In addition, it is compared with two approximate solutions, the traditional moment approximation and the Fraunhofer approximation, and a set of criteria describing their applicability are presented and interpreted.

  17. Radiation reaction and gravitational waves in the effective field theory approach

    SciTech Connect

    Galley, Chad R.; Tiglio, Manuel

    2009-06-15

    We compute the contribution to the Lagrangian from the leading order (2.5 post-Newtonian) radiation reaction and the quadrupolar gravitational waves emitted from a binary system using the effective field theory (EFT) approach of Goldberger and Rothstein. We use an initial value formulation of the underlying (quantum) framework to implement retarded boundary conditions and describe these real-time dissipative processes. We also demonstrate why the usual scattering formalism of quantum field theory inadequately accounts for these. The methods discussed here should be useful for deriving real-time quantities (including radiation reaction forces and gravitational wave emission) and hereditary terms in the post-Newtonian approximation (including memory, tail and other causal, history-dependent integrals) within the EFT approach. We also provide a consistent formulation of the radiation sector in the equivalent effective field theory approach of Kol and Smolkin.

  18. Characterization of extended range Bonner Sphere Spectrometers in the CERF high-energy broad neutron field at CERN

    NASA Astrophysics Data System (ADS)

    Agosteo, S.; Bedogni, R.; Caresana, M.; Charitonidis, N.; Chiti, M.; Esposito, A.; Ferrarini, M.; Severino, C.; Silari, M.

    2012-12-01

    The accurate determination of the ambient dose equivalent in the mixed neutron-photon fields encountered around high-energy particle accelerators still represents a challenging task. The main complexity arises from the extreme variability of the neutron energy, which spans over 10 orders of magnitude or more. Operational survey instruments, which response function attempts to mimic the fluence-to-ambient dose equivalent conversion coefficient up to GeV neutrons, are available on the market, but their response is not fully reliable over the entire energy range. Extended range rem counters (ERRC) do not require the exact knowledge of the energy distribution of the neutron field and the calibration can be done with a source spectrum. If the actual neutron field has an energy distribution different from the calibration spectrum, the measurement is affected by an added uncertainty related to the partial overlap of the fluence-to-ambient dose equivalent conversion curve and the response function. For this reason their operational use should always be preceded by an "in-field" calibration, i.e. a calibration made against a reference instrument exposed in the same field where the survey-meter will be employed. In practice the extended-range Bonner Sphere Spectrometer (ERBSS) is the only device which can serve as reference instrument in these fields, because of its wide energy range and the possibility to assess the neutron fluence and the ambient dose equivalent (H*(10)) values with the appropriate accuracy. Nevertheless, the experience gained by a number of experimental groups suggests that mandatory conditions for obtaining accurate results in workplaces are: (1) the use of a well-established response matrix, thus implying validation campaigns in reference monochromatic neutrons fields, (2) the expert and critical use of suitable unfolding codes, and (3) the performance test of the whole system (experimental set-up, elaboration and unfolding procedures) in a well

  19. Edge diffracted caustic fields. [spacecraft antenna radiation patterns

    NASA Technical Reports Server (NTRS)

    Burnside, W. D.; Peters, L., Jr.

    1974-01-01

    The fields near a caustic created by an edge diffraction process are computed using the equivalent current concept. These fields are shown to have the property commonly associated with ray optical analysis or the Geometrical Theory of Diffraction (GTD), e.g., a 90 deg phase shift as the ray passes through the caustic. The present effort is directed toward consideration of the caustic created by an edge diffraction process. Particular attention is focused on electromagnetic excitation. The acoustic excitation for the hard boundary condition is outlined in an appendix. In addition, goal is to establish the extent of the caustic region. This is of particular importance when a ray optical solution involves multiply-diffracted terms in that the minimum size of the body that can be analyzed may be restricted by the extent of the caustic, i.e., the 90 deg phase shift used in ray optical analysis may be introduced only if the caustic is contained on the surface being studied.

  20. The electric field changes and UHF radiations caused by the triggered lightning in Japan

    NASA Astrophysics Data System (ADS)

    Kawasaki, Zen-Ichiro; Kanao, Tadashi; Matsuura, Kenji; Nakano, Minoru; Horii, Kenji; Nakamura, Koh-Ichi

    1991-09-01

    The electric field changes, the magnetic field changes, and UHF radiation were observed during the rocket-triggered lightning experiment in winter storms. A remarkable discrepancy is noticed between electromagnetic field changes of flashes triggered with a rocket and an isolated wire that struck a power tower and flashes with a rocket and a grounded wire. Flashes to tower have a distinguishable first pulse of a large amplitude, which, we speculate, occurs at the moment of attachment of a downward leader to the tower. The UHF radiation measurements indicate that the triggered lightning process starts with a pulse series resembling a negative stepped leader. The electric field change records of rockettriggered lightning in winter storms do not show the presence of rapid field variations typical for return strokes in natural cloud-to-ground flashes.

  1. Extending human perception of electromagnetic radiation to the UV region through biologically inspired photochromic fuzzy logic (BIPFUL) systems.

    PubMed

    Gentili, Pier Luigi; Rightler, Amanda L; Heron, B Mark; Gabbutt, Christopher D

    2016-01-25

    Photochromic fuzzy logic systems have been designed that extend human visual perception into the UV region. The systems are founded on a detailed knowledge of the activation wavelengths and quantum yields of a series of thermally reversible photochromic compounds. By appropriate matching of the photochromic behaviour unique colour signatures are generated in response differing UV activation frequencies.

  2. The mechanism of the effect of a plasma layer with negative permittivity on the antenna radiation field

    SciTech Connect

    Wang, Chunsheng Liu, Hui; Jiang, Binhao; Li, Xueai

    2015-06-15

    A model of a plasma–antenna system is developed to study the mechanism of the effect of the plasma layer on antenna radiation. Results show a plasma layer with negative permittivity is inductive, and thus affects the phase difference between electric and magnetic fields. In the near field of antenna radiation, a plasma layer with proper parameters can compensate the capacitivity of the vacuum and enhance the radiation power. In the far field of antenna radiation, the plasma layer with negative permittivity increases the inductivity of the vacuum and reduces the radiation power.

  3. Organ dose conversion coefficients for pediatric reference computational phantoms in external photon radiation fields

    NASA Astrophysics Data System (ADS)

    Chang, Lienard A.

    In the event of a radiological accident or attack, it is important to estimate the organ doses to those exposed. In general, it is difficult to measure organ dose directly in the field and therefore dose conversion coefficients (DCC) are needed to convert measurable values such as air kerma to organ dose. Previous work on these coefficients has been conducted mainly for adults with a focus on radiation protection workers. Hence, there is a large gap in the literature for pediatric values. This study coupled a Monte Carlo N-Particle eXtended (MCNPX) code with International Council of Radiological Protection (ICRP)-adopted University of Florida and National Cancer Institute pediatric reference phantoms to calculate a comprehensive list of dose conversion coefficients (mGy/mGy) to convert air-kerma to organ dose. Parameters included ten phantoms (newborn, 1-year, 5-year, 10-year, 15-year old male and female), 28 organs over 33 energies between 0.01 and 20 MeV in six (6) irradiation geometries relevant to a child who might be exposed to a radiological release: anterior-posterior (AP), posterior-anterior (PA), right-lateral (RLAT), left-lateral (LLAT), rotational (ROT), and isotropic (ISO). Dose conversion coefficients to the red bone marrow over 36 skeletal sites were also calculated. It was hypothesized that the pediatric organ dose conversion coefficients would follow similar trends to the published adult values as dictated by human anatomy, but be of a higher magnitude. It was found that while the pediatric coefficients did yield similar patterns to that of the adult coefficients, depending on the organ and irradiation geometry, the pediatric values could be lower or higher than that of the adult coefficients.

  4. Ultraviolet radiation penetrating vehicle glass: a field based comparative study

    NASA Astrophysics Data System (ADS)

    Kimlin, M. G.; Parisi, A. V.

    1999-04-01

    The solar UV transmitted through automobile glass was measured in the field in two cars using a spectroradiometer. The two cars were identical except that one of the cars had all of the windows (except the windshield) tinted. The measured spectral erythemal UV on a horizontal plane with the windows fully closed was reduced in the tinted car by a factor of 42 when compared with the erythemal UV measured in the untinted car. The ambient UVA irradiances at various locations within four different makes of car and a tractor were also measured with a broad band UVA hand-held meter. The average normalized daily UVA exposure (measured with a broad band UVA meter) was 1.3 times higher in a large family sedan when compared with that in a small hatchback and the UVA exposure in a car with tinted windows was 3.8 times less than in a similar untinted car.

  5. EPR dosimetry in a mixed neutron and gamma radiation field.

    PubMed

    Trompier, F; Fattibene, P; Tikunov, D; Bartolotta, A; Carosi, A; Doca, M C

    2004-01-01

    Suitability of Electron Paramagnetic Resonance (EPR) spectroscopy for criticality dosimetry was evaluated for tooth enamel, mannose and alanine pellets during the 'international intercomparison of criticality dosimetry techniques' at the SILENE reactor held in Valduc in June 2002, France. These three materials were irradiated in neutron and gamma-ray fields of various relative intensities and spectral distributions in order to evaluate their neutron sensitivity. The neutron response was found to be around 10% for tooth enamel, 45% for mannose and between 40 and 90% for alanine pellets according their type. According to the IAEA recommendations on the early estimate of criticality accident absorbed dose, analyzed results show the EPR potentiality and complementarity with regular criticality techniques.

  6. ROTATION AND STABILITY OF THE TOROIDAL MAGNETIC FIELD IN STELLAR RADIATION ZONES

    SciTech Connect

    Bonanno, Alfio; Urpin, Vadim E-mail: vadim.urpin@uv.es

    2013-03-20

    The stability of the magnetic field in radiation zones is of crucial importance for mixing and angular momentum transport in the stellar interior. We consider the stability properties of stars containing a predominant toroidal field in spherical geometry by means of a linear stability in the Boussinesq approximation taking into account the effect of thermal conductivity. We calculate the growth rate of instability and analyze in detail the effects of stable stratification and heat transport. We argue that the stabilizing influence of gravity can never entirely suppress the instability caused by electric currents in radiation zones. However, the stable stratification can essentially decrease the growth rate of instability.

  7. Temperature Measurement of a Miniature Ceramic Heater in the Presence of an Extended Interfering Background Radiation Source Using a Multiwavelength Pyrometer

    NASA Technical Reports Server (NTRS)

    Ng, Daniel

    1999-01-01

    Temperature measurement of small (millimeter size) objects is generally difficult and demanding. Measurement involving ceramic materials using the traditional one- and two-color pyrometer is difficult because of their complex optical properties, such as low emissivity which may vary with both temperature and wavelength. Pyrometry applications in an environment with an interfering radiation source of extended dimension adds extra complexity to the process. We show that the multiwavelength pyrometer successfully measured the temperatures of a millimeter (mm) size ceramic heater under these demanding conditions.

  8. First-order quantum correction to the Larmor radiation from a moving charge in a spatially homogeneous time-dependent electric field

    SciTech Connect

    Yamamoto, Kazuhiro; Nakamura, Gen

    2011-02-15

    First-order quantum correction to the Larmor radiation is investigated on the basis of the scalar QED on a homogeneous background of a time-dependent electric field, which is a generalization of a recent work by Higuchi and Walker so as to be extended for an accelerated charged particle in a relativistic motion. We obtain a simple approximate formula for the quantum correction in the limit of the relativistic motion when the direction of the particle motion is parallel to that of the electric field.

  9. Online virtual isocenter based radiation field targeting for high performance small animal microirradiation

    NASA Astrophysics Data System (ADS)

    Stewart, James M. P.; Ansell, Steve; Lindsay, Patricia E.; Jaffray, David A.

    2015-12-01

    Advances in precision microirradiators for small animal radiation oncology studies have provided the framework for novel translational radiobiological studies. Such systems target radiation fields at the scale required for small animal investigations, typically through a combination of on-board computed tomography image guidance and fixed, interchangeable collimators. Robust targeting accuracy of these radiation fields remains challenging, particularly at the millimetre scale field sizes achievable by the majority of microirradiators. Consistent and reproducible targeting accuracy is further hindered as collimators are removed and inserted during a typical experimental workflow. This investigation quantified this targeting uncertainty and developed an online method based on a virtual treatment isocenter to actively ensure high performance targeting accuracy for all radiation field sizes. The results indicated that the two-dimensional field placement uncertainty was as high as 1.16 mm at isocenter, with simulations suggesting this error could be reduced to 0.20 mm using the online correction method. End-to-end targeting analysis of a ball bearing target on radiochromic film sections showed an improved targeting accuracy with the three-dimensional vector targeting error across six different collimators reduced from 0.56+/- 0.05 mm (mean  ±  SD) to 0.05+/- 0.05 mm for an isotropic imaging voxel size of 0.1 mm.

  10. Construction of Extended 3D Field of Views of the Internal Bladder Wall Surface: A Proof of Concept

    NASA Astrophysics Data System (ADS)

    Ben-Hamadou, Achraf; Daul, Christian; Soussen, Charles

    2016-09-01

    3D extended field of views (FOVs) of the internal bladder wall facilitate lesion diagnosis, patient follow-up and treatment traceability. In this paper, we propose a 3D image mosaicing algorithm guided by 2D cystoscopic video-image registration for obtaining textured FOV mosaics. In this feasibility study, the registration makes use of data from a 3D cystoscope prototype providing, in addition to each small FOV image, some 3D points located on the surface. This proof of concept shows that textured surfaces can be constructed with minimally modified cystoscopes. The potential of the method is demonstrated on numerical and real phantoms reproducing various surface shapes. Pig and human bladder textures are superimposed on phantoms with known shape and dimensions. These data allow for quantitative assessment of the 3D mosaicing algorithm based on the registration of images simulating bladder textures.

  11. Transient quantum coherent response to a partially coherent radiation field.

    PubMed

    Sadeq, Zaheen S; Brumer, Paul

    2014-02-21

    The response of an arbitrary closed quantum system to a partially coherent electric field is investigated, with a focus on the transient coherences in the system. As a model we examine, both perturbatively and numerically, the coherences induced in a three level V system. Both rapid turn-on and pulsed turn-on effects are investigated. The effect of a long and incoherent pulse is also considered, demonstrating that during the pulse the system shows a coherent response which reduces after the pulse is over. Both the pulsed scenario and the thermally broadened CW case approach a mixed state in the long time limit, with rates dictated by the adjacent level spacings and the coherence time of the light, and via a mechanism that is distinctly different from traditional decoherence. These two excitation scenarios are also explored for a minimal "toy" model of the electronic levels in pigment protein complex PC645 by both a collisionally broadened CW laser and by a noisy pulse, where unexpectedly long transient coherence times are observed and explained. The significance of environmentally induced decoherence is noted.

  12. Transient quantum coherent response to a partially coherent radiation field

    SciTech Connect

    Sadeq, Zaheen S.; Brumer, Paul

    2014-02-21

    The response of an arbitrary closed quantum system to a partially coherent electric field is investigated, with a focus on the transient coherences in the system. As a model we examine, both perturbatively and numerically, the coherences induced in a three level V system. Both rapid turn-on and pulsed turn-on effects are investigated. The effect of a long and incoherent pulse is also considered, demonstrating that during the pulse the system shows a coherent response which reduces after the pulse is over. Both the pulsed scenario and the thermally broadened CW case approach a mixed state in the long time limit, with rates dictated by the adjacent level spacings and the coherence time of the light, and via a mechanism that is distinctly different from traditional decoherence. These two excitation scenarios are also explored for a minimal “toy” model of the electronic levels in pigment protein complex PC645 by both a collisionally broadened CW laser and by a noisy pulse, where unexpectedly long transient coherence times are observed and explained. The significance of environmentally induced decoherence is noted.

  13. Extended-gate field-effect transistor (EG-FET) with molecularly imprinted polymer (MIP) film for selective inosine determination.

    PubMed

    Iskierko, Zofia; Sosnowska, Marta; Sharma, Piyush Sindhu; Benincori, Tiziana; D'Souza, Francis; Kaminska, Izabela; Fronc, Krzysztof; Noworyta, Krzysztof

    2015-12-15

    A novel recognition unit of chemical sensor for selective determination of the inosine, renal disfunction biomarker, was devised and prepared. For that purpose, inosine-templated molecularly imprinted polymer (MIP) film was deposited on an extended-gate field-effect transistor (EG-FET) signal transducing unit. The MIP film was prepared by electrochemical polymerization of bis(bithiophene) derivatives bearing cytosine and boronic acid substituents, in the presence of the inosine template and a thiophene cross-linker. After MIP film deposition, the template was removed, and was confirmed by UV-visible spectroscopy. Subsequently, the film composition was characterized by spectroscopic techniques, and its morphology and thickness were determined by AFM. The finally MIP film-coated extended-gate field-effect transistor (EG-FET) was used for signal transduction. This combination is not widely studied in the literature, despite the fact that it allows for facile integration of electrodeposited MIP film with FET transducer. The linear dynamic concentration range of the chemosensor was 0.5-50 μM with inosine detectability of 0.62 μM. The obtained detectability compares well to the levels of the inosine in body fluids which are in the range 0-2.9 µM for patients with diagnosed diabetic nephropathy, gout or hyperuricemia, and can reach 25 µM in certain cases. The imprinting factor for inosine, determined from piezomicrogravimetric experiments with use of the MIP film-coated quartz crystal resonator, was found to be 5.5. Higher selectivity for inosine with respect to common interferents was also achieved with the present molecularly engineered sensing element. The obtained analytical parameters of the devised chemosensor allow for its use for practical sample measurements.

  14. Defeating radiation damping and magnetic field inhomogeneity with spatially encoded noise.

    PubMed

    Michal, Carl A

    2010-11-15

    A simple NMR experiment capable of providing well resolved spectra under conditions where either radiation damping or static magnetic field inhomogeneity would broaden otherwise high-resolution NMR spectra is introduced. The approach involves using a strong pulsed magnetic field gradient and a selective radio-frequency pulse to encode a predetermined noise pattern into the spatial distribution of magnetization. Following readout in a much smaller field gradient, the noise sequence may be deconvolved from the acquired data and a high-resolution spectrum is obtained, eliminating the effects of either radiation damping or the static field inhomogeneity. In the presence of field inhomogeneity a field map is also obtained from the same single transient. A quasi-two-dimensional version of the experiment eliminates the need for deconvolution and produces improved results with simplified processing, but without requiring a full two-dimensional experiment. Example spectra are shown for both radiation damping and one-dimensional field inhomogeneity with improvement in linewidths of more than a factor of 40.

  15. Development of a cryogenic radiation detector for mapping radio frequency superconducting cavity field emissions

    SciTech Connect

    Danny Dotson; John Mammosser

    2005-05-01

    Field emissions in a super conducting helium cooled RF cavity and the production of radiation (mostly X-Rays) have been measured externally on cryomodules at Jefferson Lab since 1991. External measurements are limited to radiation energies above 100 keV due to shielding of the stainless steel cryogenic body. To measure the onset of and to map field emissions from a superconducting cavity requires the detecting instrument be inside the shield and within the liquid Helium. Two possible measurement systems are undergoing testing at JLab. A CsI detector array set on photodiodes and an X-Ray film camera with a fixed aperture. Several devices were tested in the cell with liquid Helium without success. The lone survivor, a CsI array, worked but saturated at high power levels due to backscatter. The array was encased in a lead shield with a slit opening set to measure the radiation emitted directly from the cell eliminating a large portion of the backscatter. This is a work in progress and te sting should be complete before the PAC 05. The second system being tested is passive. It is a shielded box with an aperture to expose radiation diagnostic film located inside to direct radiation from the cell. Developing a technique for mapping field emissions in cryogenic cells will assist scientists and engineers in pinpointing any surface imperfections for examination.

  16. Analytic theory for betatron radiation from relativistic electrons in ion plasma channels with magnetic field

    SciTech Connect

    Lee, H. C.; Jiang, T. F.

    2010-11-15

    We analytically solve the relativistic equation of motion for an electron in ion plasma channels and calculate the corresponding trajectory as well as the synchrotron radiation. The relativistic effect on a trajectory is strong, i.e., many high-order harmonic terms in the trajectory, when the ratio of the initial transverse velocity (v{sub x0}) to the longitudinal velocity (v{sub z0}) of the electron injected to ion plasma channels is high. Interestingly, these high-order harmonic terms result in a quite broad and intense radiation spectrum, especially at an oblique angle, in contrast to an earlier understanding. As the initial velocity ratio (v{sub x0}:v{sub z0}) decreases, the relativistic effect becomes weak; only the first and second harmonic terms remain in the transverse and longitudinal trajectories, respectively, which coincides with the result of Esarey et al. [Phys. Rev. E 65, 056505 (2002)]. Our formalism also allows the description of electron's trajectory in the presence of an applied magnetic field. Critical magnetic fields for cyclotron motions are figured out and compared with semiclassical results. The cyclotron motion leads to more high-order harmonic terms than the trajectory without magnetic fields and causes an immensely broad spectrum with vastly large radiation amplitude for high initial velocity ratios (v{sub x0}:v{sub z0}). The radiation from hard x-ray to gamma-ray regions can be generated with a broad radiation angle, thus available for applications.

  17. On Whether Angular Momentum in Electric and Magnetic Fields Radiates to Infinity

    NASA Technical Reports Server (NTRS)

    Canning, Francis X.; Knudsen, Steven

    2006-01-01

    The Feynman Disk experiment and a related thought experiment with a static magnetic field and capacitor are studied. The mechanical torque integrated over time (angular impulse) is related to the angular momentum in the electric/magnetic field. This is not called an electromagnetic field since quasi-static as well as electromagnetic effects are included. The angular momentum in the electric/magnetic field is examined to determine its static and radiative components. This comparison was then examined to see if it clarified the Abraham-Minkowski paradox.

  18. Repulsive gravity induced by a conformally coupled scalar field implies a bouncing radiation-dominated universe

    NASA Astrophysics Data System (ADS)

    Antunes, V.; Novello, M.

    2017-04-01

    In the present work we revisit a model consisting of a scalar field with a quartic self-interaction potential non-minimally (conformally) coupled to gravity (Novello in Phys Lett 90A:347 1980). When the scalar field vacuum is in a broken symmetry state, an effective gravitational constant emerges which, in certain regimes, can lead to gravitational repulsive effects when only ordinary radiation is coupled to gravity. In this case, a bouncing universe is shown to be the only cosmological solution admissible by the field equations when the scalar field is in such broken symmetry state.

  19. The Amplitude Nth-Power Squeezing of Radiation Fields in the Degenerate Raman Process

    NASA Technical Reports Server (NTRS)

    Zhang, Zhi-Ming; Pan, Jin-Fang; Xu, Lei

    1996-01-01

    In this paper we study the amplitude Nth-power squeezing of radiation fields in the degenerate Raman process by using the modified effective Hamiltonian approach recently suggested by us. We found that if the field is initially in a coherent state it will not get squeezing for any Nth-power; if the field is initially in a squeezed vacuum, it may get Nth-power squeezing. The time evolution of the field fluctuation was discussed. Its dependences on power-order N, mean photon number bar-n, and squeezing angle xi are analyzed.

  20. Radiation force on a spherical object in the field of a focused cylindrical transducer.

    PubMed

    Chen, X; Apfel, R E

    1997-05-01

    An exact solution of the radiation force on a spherical object, when positioned on the acoustic axis of a cylindrical transducer, is provided. The solution is valid for any type of sphere of any size. The radiation force function allows the calibration of high-frequency focused ultrasound fields from radiation force measurements and expands the utility of the elastic sphere radiometer developed by Dunn et al. [Acustica 38, 58-61 (1977)]. Numeral results reveal an oscillatory behavior of the radiation force function for small spheres near the transducer surface and this behavior may present an opportunity for particle sorting based on the mechanical properties of the particle and other types of manipulation.

  1. Study of shockwave method for diagnosing the radiation fields of laser-driven gold hohlraums

    NASA Astrophysics Data System (ADS)

    Li, Yongsheng; Lan, Ke; Huo, Wenyi; Lai, Dongxian; Gao, Yaoming; Pei, Wenbing

    2013-11-01

    Besides the routinely used broad-band x-ray spectrometer (Dante or SXS), ablative shock-wave method is often used to diagnose the radiation fields of laser-driven Hohlraums. The x-ray ablation process of Aluminum and Titanium is studied numerically with a 1-D radiation hydrodynamic code RDMG [F. Tinggui et al., Chin. J. Comput. Phys. 16, 199 (1999)], based on which a new scaling relation of the equivalent radiation temperature with the ablative shock velocity in Aluminum plates is proposed, and a novel method is developed for determining simultaneously the radiation temperature and the M-band (2-4 keV) fraction in laser-driven gold Hohlraums.

  2. On Consideration of Radiated Power in RF Field Simulations for MRI

    PubMed Central

    Liu, Wanzhan; Kao, Chien-ping; Collins, Christopher M.; Smith, Michael B.; Yang, Qing X.

    2012-01-01

    In numerical analyses of RF fields for MRI, RF power is often permitted to radiate out of the problem region. In reality, RF power will be confined by the magnet bore and RF screen enclosing the magnet room. We present numerical calculations at different frequencies for various surface and volume coils, with samples from simple spheres to the human body in environments from free space to a shielded RF room. Results for calculations within a limited problem region show radiated power increases with frequency. When the magnet room RF screen is included, nearly all the power is dissipated in the human subject. For limited problem regions, inclusion of a term for radiation loss results in an underestimation of transmit efficiency compared to results including the complete bore and RF screen. If the term for radiated power is not included, calculated coil efficiencies are slightly overestimated compared to the complete case. PMID:22473620

  3. Consideration of the radiation dose delivered away from the treatment field to patients in radiotherapy

    PubMed Central

    Taylor, Michael L.; Kron, Tomas

    2011-01-01

    Radiation delivery to cancer patients for radiotherapy is invariably accompanied by unwanted radiation to other parts of the patient’s body. Traditionally, considerable effort has been made to calculate and measure the radiation dose to the target as well as to nearby critical structures. Only recently has attention been focused also on the relatively low doses that exist far from the primary radiation beams. In several clinical scenarios, such doses have been associated with cardiac toxicity as well as an increased risk of secondary cancer induction. Out-of-field dose is a result of leakage and scatter and generally difficult to predict accurately. The present review aims to present existing data, from measurements and calculations, and discuss its implications for radiotherapy. PMID:21731221

  4. Field Dynamics of Coherent Synchrotron Radiation Using a Direct Numerical Solution of Maxwell's Equations

    SciTech Connect

    Novokhatski, A.; /SLAC

    2011-08-17

    We present and discuss the properties of the coherent electromagnetic fields of a very short, ultrarelativistic bunch in a rectangular vacuum chamber inside a bending magnet. The analysis is based on the results of a direct numerical solution of Maxwell's equations together with Newton's equations. We use a new dispersion-free time-domain algorithm which employs a more efficient use of finite element mesh techniques and, hence, produces self-consistent and stable solutions for very short bunches. We investigate the fine structure of the coherent synchrotron radiation fields. We also discuss coherent edge radiation. We present a clear picture of the field using the electric field lines constructed from the numerical solutions. This method should be useful in the study of existing and future concepts of particle accelerators and ultrafast coherent light sources, where high peak currents and very short bunches are envisioned.

  5. Radiative widths and splitting of cyclotron lines in superstrong magnetic fields

    NASA Technical Reports Server (NTRS)

    Pavlov, G. G.; Bezchastnov, V. G.; Meszaros, P.; Alexander, S. G.

    1991-01-01

    The radiative line widths of the Landau levels in a superstrong magnetic field are calculated and simple analytic expressions and fits are given for these which are valid over a wide range of the principal quantum number and the magnetic field strength. If QED corrections are not taken into account, all levels but the first are doubly degenerate, corresponding to the two possible spin projections. However, the interaction with the QED vacuum removes this degeneracy, leading to an energy splitting of each level which exceeds the radiative linewidth for low Landau levels if the magnetic field is not too large (B is less than approximately 10 exp 13 G). Estimations are presented of the splitting in various limits as a function of field strength and Landau number. The possibility of observing this splitting in accreting X-ray pulsars and in gamma-ray bursters is discussed.

  6. Assessment of the ultraviolet radiation field in ocean waters from space-based measurements and full radiative-transfer calculations.

    PubMed

    Vasilkov, Alexander P; Herman, Jay R; Ahmad, Ziauddin; Kahru, Mati; Mitchell, B Greg

    2005-05-10

    Quantitative assessment of the UV effects on aquatic ecosystems requires an estimate of the in-water radiation field. Actual ocean UV reflectances are needed for improving the total ozone retrievals from the total ozone mapping spectrometer (TOMS) and the ozone monitoring instrument (OMI) flown on NASA's Aura satellite. The estimate of underwater UV radiation can be done on the basis of measurements from the TOMS/OMI and full models of radiative transfer (RT) in the atmosphere-ocean system. The Hydrolight code, modified for extension to the UV, is used for the generation of look-up tables for in-water irradiances. A look-up table for surface radiances generated with a full RT code is input for the Hydrolight simulations. A model of seawater inherent optical properties (IOPs) is an extension of the Case 1 water model to the UV. A new element of the IOP model is parameterization of particulate matter absorption based on recent in situ data. A chlorophyll product from ocean color sensors is input for the IOP model. Verification of the in-water computational scheme shows that the calculated diffuse attenuation coefficient Kd is in good agreement with the measured Kd.

  7. On the electromagnetic fields, Poynting vector, and peak power radiated by lightning return strokes

    NASA Technical Reports Server (NTRS)

    Krider, E. P.

    1992-01-01

    The initial radiation fields, Poynting vector, and total electromagnetic power that a vertical return stroke radiates into the upper half space have been computed when the speed of the stroke, nu, is a significant fraction of the speed of light, c, assuming that at large distances and early times the source is an infinitesimal dipole. The initial current is also assumed to satisfy the transmission-line model with a constant nu and to be perpendicular to an infinite, perfectly conducting ground. The effect of a large nu is to increase the radiation fields by a factor of (1-beta-sq cos-sq theta) exp -1, where beta = nu/c and theta is measured from the vertical, and the Poynting vector by a factor of (1-beta-sq cos-sq theta) exp -2.

  8. Radiative transfer equations in broad-band, time-varying fields

    NASA Technical Reports Server (NTRS)

    Cooper, J.; Zoller, P.

    1984-01-01

    A derivation of the equation of transfer is obtained by starting with Maxwell's equations in the 'slowly varying envelope' form. Particular attention is paid to characterizing the intensity that is 'seen' by the atom (which is found to be related to a Wigner distribution of the electric field). The equation of transfer is found to be valid for 'broad-band' slowly varying radiation fields.

  9. Delineation of electric and magnetic field effects of extremely low frequency electromagnetic radiation on transcription

    SciTech Connect

    Greene, J.J.; Skowronski, W.J.; Mullins, J.M.; Nardone, R.M.; Penafiel, M.; Meister, R. )

    1991-01-31

    The relative effects of the electric and magnetic field components of extremely low frequency electromagnetic radiation (ELF) on transcription were examined in human leukemia HL-60 cells. Delineation of the individual field contributions was achieved by irradiating cells in separate concentric compartments of a culture dish within a solenoid chamber. This exposure system produced a homogeneous magnetic field with a coincident electric field whose strength varied directly with distance from the center of the culture dish. Irradiation of HL-60 cells with sine wave ELF at 60 Hz and a field strength of 10 Gauss produced a transient increase in the transcriptional rates which reached a maximum of 50-60% enhancement at 30-120 minutes of irradiation and declined to near basal levels by 18 hours. Comparison of transcription responses to ELF of cells in different concentric compartments revealed that the transcriptional effects were primarily the result of the electric field component with little or no contribution from the magnetic field.

  10. Quasinormal modes, scattering, and Hawking radiation of Kerr-Newman black holes in a magnetic field

    SciTech Connect

    Kokkotas, K. D.; Konoplya, R. A.; Zhidenko, A.

    2011-01-15

    We perform a comprehensive analysis of the spectrum of proper oscillations (quasinormal modes), transmission/reflection coefficients, and Hawking radiation for a massive charged scalar field in the background of the Kerr-Newman black hole immersed in an asymptotically homogeneous magnetic field. There are two main effects: the Zeeman shift of the particle energy in the magnetic field and the difference of values of an electromagnetic potential between the horizon and infinity, i.e. the Faraday induction. We have shown that 'turning on' the magnetic field induces a stronger energy-emission rate and leads to 'recharging' of the black hole. Thus, a black hole immersed in a magnetic field evaporates much quicker, achieving thereby an extremal state in a shorter period of time. Quasinormal modes are moderately affected by the presence of a magnetic field which is assumed to be relatively small compared to the gravitational field of the black hole.

  11. 14 CFR 25.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-intensity Radiated Fields (HIRF... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment General § 25.1317 High... that performs a function whose failure would significantly reduce the capability of the airplane or...

  12. 14 CFR 27.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-intensity Radiated Fields (HIRF... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment General § 27.1317 High... performs a function whose failure would significantly reduce the capability of the rotorcraft or...

  13. An analysis of the radiation field beneath a bank of tubular quartz lamps

    NASA Technical Reports Server (NTRS)

    Ash, Robert L.

    1972-01-01

    Equations governing the incident heat flux distribution beneath a lamp-reflector system were developed. Analysis of a particular radiant heating facility showed good agreement between theory and experiment when a lamp power loss correction was used. In addition, the theory was employed to estimate thermal disruption in the radiation field caused by a protruding probe.

  14. A scalable, fully implicit algorithm for the reduced two-field low-β extended MHD model

    SciTech Connect

    Chacon, Luis; Stanier, Adam John

    2016-12-01

    Here, we demonstrate a scalable fully implicit algorithm for the two-field low-β extended MHD model. This reduced model describes plasma behavior in the presence of strong guide fields, and is of significant practical impact both in nature and in laboratory plasmas. The model displays strong hyperbolic behavior, as manifested by the presence of fast dispersive waves, which make a fully implicit treatment very challenging. In this study, we employ a Jacobian-free Newton–Krylov nonlinear solver, for which we propose a physics-based preconditioner that renders the linearized set of equations suitable for inversion with multigrid methods. As a result, the algorithm is shown to scale both algorithmically (i.e., the iteration count is insensitive to grid refinement and timestep size) and in parallel in a weak-scaling sense, with the wall-clock time scaling weakly with the number of cores for up to 4096 cores. For a 4096 × 4096 mesh, we demonstrate a wall-clock-time speedup of ~6700 with respect to explicit algorithms. The model is validated linearly (against linear theory predictions) and nonlinearly (against fully kinetic simulations), demonstrating excellent agreement.

  15. Vlasov formalism for extended relativistic mean field models: The crust-core transition and the stellar matter equation of state

    NASA Astrophysics Data System (ADS)

    Pais, Helena; Providência, Constança

    2016-07-01

    The Vlasov formalism is extended to relativistic mean field hadron models with nonlinear terms up to fourth order and applied to the calculation of the crust-core transition density. The effect of the nonlinear ω ρ and σ ρ coupling terms on the crust-core transition density and pressure and on the macroscopic properties of some families of hadronic stars is investigated. For that purpose, six families of relativistic mean field models are considered. Within each family, the members differ in the symmetry energy behavior. For all the models, the dynamical spinodals are calculated, and the crust-core transition density and pressure and the neutron star mass-radius relations are obtained. The effect on the star radius of the inclusion of a pasta calculation in the inner crust is discussed. The set of six models that best satisfy terrestrial and observational constraints predicts a radius of 13.6 ±0.3 km and a crust thickness of 1.36 ±0.06 km for a 1.4 M⊙ star.

  16. Matter bounce cosmology with a generalized single field: non-Gaussianity and an extended no-go theorem

    NASA Astrophysics Data System (ADS)

    Li, Yu-Bin; Quintin, Jerome; Wang, Dong-Gang; Cai, Yi-Fu

    2017-03-01

    We extend the matter bounce scenario to a more general theory in which the background dynamics and cosmological perturbations are generated by a k-essence scalar field with an arbitrary sound speed. When the sound speed is small, the curvature perturbation is enhanced, and the tensor-to-scalar ratio, which is excessively large in the original model, can be sufficiently suppressed to be consistent with observational bounds. Then, we study the primordial three-point correlation function generated during the matter-dominated contraction stage and find that it only depends on the sound speed parameter. Similar to the canonical case, the shape of the bispectrum is mainly dominated by a local form, though for some specific sound speed values a new shape emerges and the scaling behaviour changes. Meanwhile, a small sound speed also results in a large amplitude of non-Gaussianities, which is disfavored by current observations. As a result, it does not seem possible to suppress the tensor-to-scalar ratio without amplifying the production of non-Gaussianities beyond current observational constraints (and vice versa). This suggests an extension of the previously conjectured no-go theorem in single field nonsingular matter bounce cosmologies, which rules out a large class of models. However, the non-Gaussianity results remain as a distinguishable signature of matter bounce cosmology and have the potential to be detected by observations in the near future.

  17. A scalable, fully implicit algorithm for the reduced two-field low-β extended MHD model

    NASA Astrophysics Data System (ADS)

    Chacón, L.; Stanier, A.

    2016-12-01

    We demonstrate a scalable fully implicit algorithm for the two-field low-β extended MHD model. This reduced model describes plasma behavior in the presence of strong guide fields, and is of significant practical impact both in nature and in laboratory plasmas. The model displays strong hyperbolic behavior, as manifested by the presence of fast dispersive waves, which make a fully implicit treatment very challenging. In this study, we employ a Jacobian-free Newton-Krylov nonlinear solver, for which we propose a physics-based preconditioner that renders the linearized set of equations suitable for inversion with multigrid methods. As a result, the algorithm is shown to scale both algorithmically (i.e., the iteration count is insensitive to grid refinement and timestep size) and in parallel in a weak-scaling sense, with the wall-clock time scaling weakly with the number of cores for up to 4096 cores. For a 4096 × 4096 mesh, we demonstrate a wall-clock-time speedup of ∼6700 with respect to explicit algorithms. The model is validated linearly (against linear theory predictions) and nonlinearly (against fully kinetic simulations), demonstrating excellent agreement.

  18. A scalable, fully implicit algorithm for the reduced two-field low-β extended MHD model

    DOE PAGES

    Chacon, Luis; Stanier, Adam John

    2016-12-01

    Here, we demonstrate a scalable fully implicit algorithm for the two-field low-β extended MHD model. This reduced model describes plasma behavior in the presence of strong guide fields, and is of significant practical impact both in nature and in laboratory plasmas. The model displays strong hyperbolic behavior, as manifested by the presence of fast dispersive waves, which make a fully implicit treatment very challenging. In this study, we employ a Jacobian-free Newton–Krylov nonlinear solver, for which we propose a physics-based preconditioner that renders the linearized set of equations suitable for inversion with multigrid methods. As a result, the algorithm ismore » shown to scale both algorithmically (i.e., the iteration count is insensitive to grid refinement and timestep size) and in parallel in a weak-scaling sense, with the wall-clock time scaling weakly with the number of cores for up to 4096 cores. For a 4096 × 4096 mesh, we demonstrate a wall-clock-time speedup of ~6700 with respect to explicit algorithms. The model is validated linearly (against linear theory predictions) and nonlinearly (against fully kinetic simulations), demonstrating excellent agreement.« less

  19. A uniform geometrical optics and an extended uniform geometrical theory of diffraction for evaluating high frequency EM fields near smooth caustics and composite shadow boundaries

    NASA Technical Reports Server (NTRS)

    Constantinides, E. D.; Marhefka, R. J.

    1994-01-01

    A uniform geometrical optics (UGO) and an extended uniform geometrical theory of diffraction (EUTD) are developed for evaluating high frequency electromagnetic (EM) fields within transition regions associated with a two and three dimensional smooth caustic of reflected rays and a composite shadow boundary formed by the caustic termination or the confluence of the caustic with the reflection shadow boundary (RSB). The UGO is a uniform version of the classic geometrical optics (GO). It retains the simple ray optical expressions of classic GO and employs a new set of uniform reflection coefficients. The UGO also includes a uniform version of the complex GO ray field that exists on the dark side of the smooth caustic. The EUTD is an extension of the classic uniform geometrical theory of diffraction (UTD) and accounts for the non-ray optical behavior of the UGO reflected field near caustics by using a two-variable transition function in the expressions for the edge diffraction coefficients. It also uniformly recovers the classic UTD behavior of the edge diffracted field outside the composite shadow boundary transition region. The approach employed for constructing the UGO/EUTD solution is based on a spatial domain physical optics (PO) radiation integral representation for the fields which is then reduced using uniform asymptotic procedures. The UGO/EUTD analysis is also employed to investigate the far-zone RCS problem of plane wave scattering from two and three dimensional polynomial defined surfaces, and uniform reflection, zero-curvature, and edge diffraction coefficients are derived. Numerical results for the scattering and diffraction from cubic and fourth order polynomial strips are also shown and the UGO/EUTD solution is validated by comparison to an independent moment method (MM) solution. The UGO/EUTD solution is also compared with the classic GO/UTD solution. The failure of the classic techniques near caustics and composite shadow boundaries is clearly

  20. Star Formation in the Galaxy and the Fluctuating UV Radiation Field

    NASA Technical Reports Server (NTRS)

    Hollenbach, David; Parravano, A.; McKee, C.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    We examine the formation of massive stars in the Galaxy, the resultant fluctuating UV radiation field, and the effect of this Field on the star-forming interstellar medium. Following previous researchers such as Habing (1968), we calculate the average interstellar radiation field at the Solar Circle of the Galaxy. However, our new calculations follow more closely the time dependence of the field at any point. We show that there is a significant difference between the mean field and the median field, and that there are substantial fluctuations of the field (on timescales of order 100 million years) at a given point. Far Ultraviolet Radiation (FUV, photon energies of 6 eV - 13.6 eV) has been recognized as the main source of heating of the neutral interstellar gas. Given the pressure of the interstellar medium (ISM) the FUV field determines whether the thermal balance of the neutral gas results in cold (T approximately 50 - 100 K) clouds (CNM), warm (T about 10,000 K) (WNM), for a combination of the two (the two phase ISM) We present results for the time history of the FUV field for points in the local ISM of the Milky Way Galaxy. The presence of this fluctuating heating rate converts CNM to WNM and vice versa. We show how to calculate the average fractions of the gas in the CNM and WNM when the interstellar gas is subject to this fluctuating FUV field. The knowledge of how these fractions depend on the gas properties (i.e. mean density and composition) and on the FUV-sources (i.e. the star formation rate, or the IMF, or the size distribution of associations) is a basic step in building any detailed model of the large scale behavior of the ISM and the mutual relation between the ISM and the SFR.

  1. Methods for Autonomous Ground-based Real-Time Monitoring and Mapping of CO2 Concentrations Over Extended Two-Dimensional Fields of Interest

    NASA Astrophysics Data System (ADS)

    Zaccheo, T. S.; Pernini, T.; Botos, C.; Dobler, J. T.; Blume, N.

    2015-12-01

    The Greenhouse gas Laser Imaging Tomography Experiment (GreenLITE) combines real-time differential Laser Absorption Spectroscopy (LAS) measurements with a lightweight web-based data acquisition and product generation system to provide autonomous 24/7 monitoring of CO2. The current GreenLITE system is comprised of two transceivers and a series of retro-reflectors that continuously measure the differential transmission over a user-defined set of intersecting line-of-site paths or "chords" that form the plane of interest. These observations are first combined with in situ surface measurements of temperature (T), pressure (P) and relative humidity (RH) to compute the integrated CO2 mixing ratios based on an iterative radiative transfer modeling approach. The retrieved CO2 mixing ratios are then grouped based on observation time and employed in a sparse sample reconstruction method to provide a tomographic- like representation of the 2-D distribution of CO2 over the field of interest. This reconstruction technique defines the field of interest as a set of idealized plumes whose integrated values best match the observations. The GreenLITE system has been deployed at two primary locations; 1) the Zero Emissions Research and Technology (ZERT) center in Bozeman, Montana, in Aug-Sept 2014, where more than 200 hours of data were collected over a wide range of environmental conditions while utilizing a controlled release of CO2 into a segmented underground pipe, and 2) continuously at a carbon sequestration test facility in Feb-Aug 2015. The system demonstrated the ability to identify persistent CO2 sources at the ZERT test facility and showed strong correlation with an independent measurement using a LI-COR based system. Here we describe the measurement approach, algorithm design and extended study results.

  2. Extending measurements in long-term permanent sites using a mobile observation system: Tradeoffs between carbon sequestration and radiation budget across a climatic gradient

    NASA Astrophysics Data System (ADS)

    Ramati, Efrat; Rohatyn, Shani; Rotenberg, Eyal; Tatarinov, Fyodor; Yakir, Dan

    2015-04-01

    Recent observations from the semi-arid region in Israel showed that conversion of the local sparse shrubland to pine forest resulted in greatly increased surface radiation load due to reduced canopy albedo combined with reduced emission of thermal radiations, which overwhelmed the beneficial effects of the relatively high rates of the forest carbon sequestration. Here we extend this study across the local climatic gradient, and test the hypothesis that increased carbon sequestration and reduced differences in surface radiation budgets along the precipitation gradient, diminish the surface effects of forestation while enhancing the benefits of carbon sequestration. We used a custom-built mobile laboratory (for eddy-flux and surface radiation measurements) on a campaign basis (about two weeks per site repeated along the seasonal cycle) to compare surface-atmosphere radiative (short- and long-wave radiation) and non-radiative (net carbon uptake, NEE, evapotranspiration, ET, and sensible heat, H) fluxes in three paired sites of pine forest (Pinus halepensis) and nearby non-forested ecosystems with mean annual precipitation/temperature of 291/19.5, 543/20.8, and 755/16.4 mm/˚C, respectively. Forests NEE and ET increased with increasing precipitation along the gradient from 0.8, to 1.5 gC m-2d-1, and 0.7 to 1.3 mmol H2O m-2s-1. Forests albedo did not changed along the gradient or along the seasonal cycle (αF ~0.12), while shrub land albedo (αS) varied along the gradient and the seasonal cycle due in part to variability in soil types (from 0.31 to 0.19, on average for dry and wet sites). Sensible heat flux did not markedly changed (HF~110 Wm-2 and HS~60 Wm-2), and the net thermal radiation emission along the climatic gradient increased in the forests (-90, to -105 Wm-2) and decreased in the shrub land (-112 to -104 Wm-2). The results showed, on average, enhanced carbon sink associated with forestation of shrub land (ΔNEEF-S) increased with precipitation (from near

  3. Evaluation of Breast Sentinel Lymph Node Coverage by Standard Radiation Therapy Fields

    SciTech Connect

    Rabinovitch, Rachel Ballonoff, Ari; Newman, Francis M.S.; Finlayson, Christina

    2008-04-01

    Background: Biopsy of the breast sentinel lymph node (SLN) is now a standard staging procedure for early-stage invasive breast cancer. The anatomic location of the breast SLN and its relationship to standard radiation fields has not been described. Methods and Materials: A retrospective review of radiotherapy treatment planning data sets was performed in patients with breast cancer who had undergone SLN biopsy, and those with a surgical clip at the SLN biopsy site were identified. The location of the clip was evaluated relative to vertebral body level on an anterior-posterior digitally reconstructed radiograph, treated whole-breast tangential radiation fields, and standard axillary fields in 106 data sets meeting these criteria. Results: The breast SLN varied in vertebral body level position, ranging from T2 to T7 but most commonly opposite T4. The SLN clip was located below the base of the clavicle in 90%, and hence would be excluded from standard axillary radiotherapy fields where the inferior border is placed at this level. The clip was within the irradiated whole-breast tangent fields in 78%, beneath the superior-posterior corner multileaf collimators in 12%, and outside the tangent field borders in 10%. Conclusions: Standard axillary fields do not encompass the lymph nodes at highest risk of containing tumor in breast cancer patients. Elimination of the superior-posterior corner MLCs from the tangent field design would result in inclusion of the breast SLN in 90% of patients treated with standard whole-breast irradiation.

  4. Rounded leaf end effect of multileaf collimator on penumbra width and radiation field offset: an analytical and numerical study

    PubMed Central

    Zhou, Dong; Zhang, Hui; Ye, Peiqing

    2015-01-01

    Background Penumbra characteristics play a significant role in dose delivery accuracy for radiation therapy. For treatment planning, penumbra width and radiation field offset strongly influence target dose conformity and organ at risk sparing. Methods In this study, we present an analytical and numerical approach for evaluation of the rounded leaf end effect on penumbra characteristics. Based on the rule of half-value layer, algorithms for leaf position calculation and radiation field offset correction were developed, which were advantageous particularly in dealing with large radius leaf end. Computer simulation was performed based on the Monte Carlo codes of EGSnrc/BEAMnrc, with groups of leaf end radii and source sizes. Data processing technique of curve fitting was employed for deriving penumbra width and radiation field offset. Results Results showed that penumbra width increased with source size. Penumbra width curves for large radius leaf end were U-shaped. This observation was probably related to the fact that radiation beams penetrated through the proximal and distal leaf sides. In contrast, source size had negligible impact on radiation field offset. Radiation field offsets were found to be constant both for analytical method and numerical simulation. However, the overall resulting values of radiation field offset obtained by analytical method were slightly smaller compared with Monte Carlo simulation. Conclusions The method we proposed could provide insight into the investigation of rounded leaf end effects on penumbra characteristics. Penumbra width and radiation field offset calibration should be carefully performed to commission multileaf collimator for intensity modulated radiotherapy. PMID:26401137

  5. Evaluating a radiation monitor for mixed-field environments based on SRAM technology

    NASA Astrophysics Data System (ADS)

    Tsiligiannis, G.; Dilillo, L.; Bosio, A.; Girard, P.; Pravossoudovitch, S.; Todri, A.; Virazel, A.; Mekki, J.; Brugger, M.; Wrobel, F.; Saigne, F.

    2014-05-01

    Instruments operating in particle accelerators and colliders are exposed to radiations that are composed of particles of different types and energies. Several of these instruments often embed devices that are not hardened against radiation effects. Thus, there is a strong need for monitoring the levels of radiation inside the mixed-field radiation areas, throughout different positions. Different metrics exist for measuring the radiation damage induced to electronic devices, such as the Total Ionizing Dose (TID), the Displacement Damage (DD) and of course the fluence of particles for estimating the error rates of the electronic devices among other applications. In this paper, we propose an SRAM based monitor, that is used to define the fluence of High Energy Hadrons (HEH) by detecting Single Event Upsets in the memory array. We evaluated the device by testing it inside the H4IRRAD area of CERN, a test area that reproduces the radiation conditions inside the Large Hadron Collider (LHC) tunnel and its shielded areas. By using stability estimation methods and presenting experimental data, we prove that this device is proper to be used for such a purpose.

  6. Polarization Radiation with Turbulent Magnetic Fields from X-Ray Binaries

    NASA Astrophysics Data System (ADS)

    Zhang, Jian-Fu; Xiang, Fu-Yuan; Lu, Ju-Fu

    2017-02-01

    We study the properties of polarized radiation in turbulent magnetic fields from X-ray binary jets. These turbulent magnetic fields are composed of large- and small-scale configurations, which result in the polarized jitter radiation when the characteristic length of turbulence is less than the non-relativistic Larmor radius. On the contrary, the polarized synchrotron emission occurs, corresponding to a large-scale turbulent environment. We calculate the spectral energy distributions and the degree of polarization for a general microquasar. Numerical results show that turbulent magnetic field configurations can indeed provide a high degree of polarization, which does not mean that a uniform, large-scale magnetic field structure exists. The model is applied to investigate the properties of polarized radiation of the black-hole X-ray binary Cygnus X-1. Under the constraint of multiband observations of this source, our studies demonstrate that the model can explain the high polarization degree at the MeV tail and predict the highly polarized properties at the high-energy γ-ray region, and that the dominant small-scale turbulent magnetic field plays an important role for explaining the highly polarized observation at hard X-ray/soft γ-ray bands. This model can be tested by polarization observations of upcoming polarimeters at high-energy γ-ray bands.

  7. Improvement of terahertz field effect transistor detectors by substrate thinning and radiation losses reduction.

    PubMed

    Coquillat, Dominique; Marczewski, Jacek; Kopyt, Pawel; Dyakonova, Nina; Giffard, Benoit; Knap, Wojciech

    2016-01-11

    Phenomena of the radiation coupling to the field effect transistors based terahertz (THz) detectors are studied. We show that in the case of planar metal antennas a significant portion of incoming radiation, instead of being coupled to the transistors, is coupled to an antenna substrate leading to responsivity losses and/or cross-talk effects in the field effect based THz detector arrays. Experimental and theoretical investigations of the responsivity versus substrate thickness are performed. They clearly show how to minimize the losses by the detector/ array substrate thinning. In conclusion simple quantitative rules of losses minimization by choosing a proper substrate thickness of field effect transistor THz detectors are presented for common materials (Si, GaAs, InP, GaN) used in semiconductor technologies.

  8. Terahertz radiation induced chaotic electron transport in semiconductor superlattices with a tilted magnetic field

    SciTech Connect

    Wang, C. Wang, F.; Cao, J. C.

    2014-09-01

    Chaotic electron transport in semiconductor superlattice induced by terahertz electric field that is superimposed on a dc electric field along the superlattice axis are studied using the semiclassical motion equations including the effect of dissipation. A magnetic field that is tilted relative to the superlattice axis is also applied to the system. Numerical simulation shows that electrons in superlattice miniband exhibit complicate nonlinear oscillating modes with the influence of terahertz radiation. Transitions between frequency-locking and chaos via pattern forming bifurcations are observed with the varying of terahertz amplitude. It is found that the chaotic regions gradually contract as the dissipation increases. We attribute the appearance of complicate nonlinear oscillation in superlattice to the interaction between terahertz radiation and internal cooperative oscillating mode relative to Bloch oscillation and cyclotron oscillation.

  9. Electrically tunable near-field radiative heat transfer via ferroelectric materials

    SciTech Connect

    Huang, Yi; Boriskina, Svetlana V.; Chen, Gang

    2014-12-15

    We explore ways to actively control near-field radiative heat transfer between two surfaces that relies on electrical tuning of phonon modes of ferroelectric materials. Ferroelectrics are widely used for tunable electrical devices, such as capacitors and memory devices; however, their tunable properties have not yet been examined for heat transfer applications. We show via simulations that radiative heat transfer between two ferroelectric materials can be enhanced by over two orders of magnitude over the blackbody limit in the near field, and can be tuned as much as 16.5% by modulating the coupling between surface phonon polariton modes at the two surfaces via varying external electric fields. We then discuss how to maximize the modulation contrast for tunable thermal devices using the studied mechanism.

  10. Gamma-Gamma Absorption in the Broad Line Region Radiation Fields of Gamma-Ray Blazars

    NASA Astrophysics Data System (ADS)

    Böttcher, Markus; Els, Paul

    2016-04-01

    The expected level of γγ absorption in the Broad Line Region (BLR) radiation field of γ-ray loud Flat Spectrum Radio Quasars (FSRQs) is evaluated as a function of the location of the γ-ray emission region. This is done self-consistently with parameters inferred from the shape of the spectral energy distribution (SED) in a single-zone leptonic EC-BLR model scenario. We take into account all geometrical effects both in the calculation of the γγ opacity and the normalization of the BLR radiation energy density. As specific examples, we study the FSRQs 3C279 and PKS 1510-089, keeping the BLR radiation energy density at the location of the emission region fixed at the values inferred from the SED. We confirm previous findings that the optical depth due to γγ absorption in the BLR radiation field exceeds unity for both 3C279 and PKS 1510-089 for locations of the γ-ray emission region inside the inner boundary of the BLR. It decreases monotonically, with distance from the central engine and drops below unity for locations within the BLR. For locations outside the BLR, the BLR radiation energy density required for the production of GeV γ-rays rapidly increases beyond observational constraints, thus making the EC-BLR mechanism implausible. Therefore, in order to avoid significant γγ absorption by the BLR radiation field, the γ-ray emission region must therefore be located near the outer boundary of the BLR.

  11. The spectrum of particles radiating in cylindrical and filament magnetic fields

    NASA Astrophysics Data System (ADS)

    Peterson, F. W.

    1988-11-01

    Particle trajectories, and the energy distribution and frequency spectrum for an initially power-law distribution of particle energies, are calculated for particles radiating in cylindrical and filament magnetic fields. If there is a continuous supply of particles to the fields, the spectrum develops two "breaks". For the filament field the spectral index changes from -α at low frequencies to -α - 0.875 at high frequencies. There is also a cutoff to the spectrum. The results are applied to Cas A and the Crab Nebula.

  12. Electric field detection of coherent synchrotron radiation in a storage ring generated using laser bunch slicing

    SciTech Connect

    Katayama, I.; Shimosato, H.; Bito, M.; Furusawa, K.; Adachi, M.; Zen, H.; Kimura, S.; Katoh, M.; Shimada, M.; Yamamoto, N.; Hosaka, M.; Ashida, M.

    2012-03-12

    The electric field of coherent synchrotron radiation (CSR) generated by laser bunch slicing in a storage ring has been detected by an electro-optic sampling method. The gate pulses for sampling are sent through a large-mode-area photonic-crystal fiber. The observed electric field profile of the CSR is in good agreement with the spectrum of the CSR observed using Fourier transform far-infrared spectrometry, indicating good phase stability in the CSR. The longitudinal density profiles of electrons modulated by laser pulses were evaluated from the electric field profile.

  13. EVOLUTION OF X-RAY AND FAR-ULTRAVIOLET DISK-DISPERSING RADIATION FIELDS

    SciTech Connect

    Ingleby, Laura; Calvet, Nuria; Miller, Jon; Bergin, Edwin; Hartmann, Lee; Hernandez, Jesus; Briceno, Cesar; Espaillat, Catherine E-mail: ncalvet@umich.edu E-mail: ebergin@umich.edu E-mail: jesush@cida.ve E-mail: cespaillat@cfa.harvard.edu

    2011-04-15

    We present new X-ray and far-ultraviolet (FUV) observations of T Tauri stars covering the age range 1-10 Myr. Our goals are to observationally constrain the intensity of radiation fields responsible for evaporating gas from the circumstellar disk and to assess the feasibility of current photoevaporation models, focusing on X-ray and UV radiation. We greatly increase the number of 7-10 Myr old T Tauri stars observed in X-rays by including observations of the well-populated 25 Ori aggregate in the Orion OB1a subassociation. With these new 7-10 Myr objects, we confirm that X-ray emission remains constant from 1 to 10 Myr. We also show, for the first time, observational evidence for the evolution of FUV radiation fields with a sample of 56 accreting and non-accreting young stars spanning 1 Myr to 1 Gyr. We find that the FUV emission decreases on timescales consistent with the decline of accretion in classical T Tauri stars until reaching the chromospheric level in weak T Tauri stars and debris disks. Overall, we find that the observed strength of high-energy radiation is consistent with that required by photoevaporation models to dissipate the disks in timescales of approximately 10 Myr. Finally, we find that the high-energy fields that affect gas evolution are not similarly affecting dust evolution; in particular, we find that disks with inner clearings, transitional disks, have similar levels of FUV emission as full disks.

  14. Polarized Radiation Diagnostics for Measuring the Magnetic Field of the Outer Solar Atmosphere

    NASA Astrophysics Data System (ADS)

    Trujillo Bueno, J.

    2012-12-01

    The basic idea of optical pumping, for which Alfred Kastler received the 1966 Nobel Prize in physics, is that the absorption and scattering of light that is near-resonant with an optical transition can produce large population imbalances among the magnetic sublevels of atomic ground states as well as in excited states. The degree of this radiatively-induced atomic level polarization, which is very sensitive to the presence of magnetic fields, can be determined by observing the polarization of the scattered or transmitted spectral line radiation. Probably, the most important point for solar physics is that the outer solar atmosphere is indeed an optically pumped vapor and that the polarization of the emergent spectral line radiation can be exploited for detecting magnetic fields that are too weak and/or too tangled so as to produce measurable Zeeman polarization signals. In this talk we review some recent radiative transfer simulations of the polarization produced by optical pumping in selected IR, FUV and EUV spectral lines, showing that their sensitivity to the Hanle effect is very suitable for magnetic field measurements in the outer solar atmosphere. We argue that solar magnetometry using the spectral lines of optically pumped atoms in the chromosphere, transition region and corona should be a high-priority goal for large aperture solar telescopes, such as ATST, EST and SOLAR-C.

  15. Upper limits to near-field radiative heat transfer: generalizing the blackbody concept

    NASA Astrophysics Data System (ADS)

    Miller, Owen D.; Rodriguez, Alejandro W.; Johnson, Steven G.

    2016-09-01

    For 75 years it has been known that radiative heat transfer can exceed far-field blackbody rates when two bodies are separated by less than a thermal wavelength. Yet an open question has remained: what is the maximum achievable radiative transfer rate? Here we describe basic energy-conservation principles that answer this question, yielding upper bounds that depend on the temperatures, material susceptibilities, and separation distance, but which encompass all geometries. The simple structures studied to date fall far short of the bounds, offering the possibility for significant future enhancement, with ramifications for experimental studies as well as thermophotovoltaic applications.

  16. Development of a proposed international standard for certification of aircraft to High Intensity Radiated Fields (HIRF)

    NASA Technical Reports Server (NTRS)

    Sargent, Noel B.

    1993-01-01

    Avionic systems performing critical functions in modern aircraft are potentially susceptible to the hazards of electromagnetic radiation from ground and airborne transmitters. The Federal Aviation Administration (FAA) requested that the Society of Automotive Engineers (SAE) coordinate the development of procedures and guidance material which can be used during the aircraft certification process to ensure adequate protection against high intensity radiated fields (HIRF). This paper addresses both the technical challenge of drafting a certification procedure and guidance standard as well as the management process used by the SAE subcommittee AE4R to converge a diverse range of opinions by its international membership in the shortest possible time.

  17. Radiation reaction from electromagnetic fields in the neighborhood of a point charge

    NASA Astrophysics Data System (ADS)

    Singal, Ashok K.

    2017-03-01

    From the expression for the electromagnetic field in the neighborhood of a point charge, we determine the rate of electromagnetic momentum flow, calculated using the Maxwell stress tensor, across a surface surrounding the charge. From that we derive for a "point" charge the radiation reaction formula, which turns out to be proportional to the first time-derivative of the acceleration of the charge, identical to the expression for the self-force, hitherto obtained in the literature from the detailed mutual interaction between constituents of a small charged sphere. We then use relativistic transformations to arrive at a generalized formula for radiation reaction for a point charge undergoing relativistic motion.

  18. Strong Field-Induced Frequency Conversion of Laser Radiation in Plasma Plumes: Recent Achievements

    PubMed Central

    Ganeev, R. A.

    2013-01-01

    New findings in plasma harmonics studies using strong laser fields are reviewed. We discuss recent achievements in the growth of the efficiency of coherent extreme ultraviolet (XUV) radiation sources based on frequency conversion of the ultrashort pulses in the laser-produced plasmas, which allowed for the spectral and structural studies of matter through the high-order harmonic generation (HHG) spectroscopy. These studies showed that plasma HHG can open new opportunities in many unexpected areas of laser-matter interaction. Besides being considered as an alternative method for generation of coherent XUV radiation, it can be used as a powerful tool for various spectroscopic and analytical applications. PMID:23864818

  19. Would Larger Radiation Fields Lead to a Faster Onset of Pain Relief in the Palliation of Bone Metastases?

    SciTech Connect

    Chow, Edward Makhani, Leila; Culleton, Shaelyn; Makhani, Nadiya; Davis, Lori; Campos, Sarah; Sinclair, Emily

    2009-08-01

    Purpose: Hemibody irradiation has been shown to relieve bony metastatic pain within 24-48 hours of treatment, whereas for local external beam radiation, onset of pain relief is 1-4 weeks after radiation. The primary objective of this study is to examine whether there is a relationship between the areas of radiation treatment and onset of pain relief. Methods and Materials: From Jan 1999 to Jan 2002, a total of 653 patients with symptomatic bone metastases were treated with external beam radiation. Pain scores and analgesic consumption were recorded at baseline and Weeks 1, 2, 4, 8, and 12. The areas of radiation treatment for all patients were calculated, then correlated with the response and analyzed in various ways. We first compared pain score alone with mean radiation field size. Second, we combined pain score and analgesic consumption. Last, we implemented the International Consensus end points for pain score and analgesic intake. Results: Assessment of 653 patients showed no significant correlation comparing pain scores alone with radiation field area, with the exception of Week 4 for partial responders. Again, no significant correlation was found when combining both analgesic intake and pain score against radiation field size. Even when implementing the International Consensus end point definitions for radiation response, the only significant correlation between radiation field size and response was observed in Week 2 for partial response. Conclusion: There was no statistical significance between mean areas of radiation treatment with the onset of pain relief.

  20. Absorption of infrared radiation by electrons in the field of a neutral hydrogen atom

    NASA Technical Reports Server (NTRS)

    Stallcop, J. R.

    1974-01-01

    An analytical expression for the absorption coefficient is developed from a relationship between the cross-section for inverse bremsstrahlung absorption and the cross-section for electron-atom momentum transfer; it is accurate for those photon frequencies v and temperatures such that hv/kT is small. The determination of the absorption of infrared radiation by free-free transitions of the negative hydrogen ion has been extended to higher temperatures. A simple analytical expression for the absorption coefficient has been derived.

  1. Characterisation of radiation field for irradiation of biological samples at nuclear reactor-comparison of twin detector and recombination methods.

    PubMed

    Golnik, N; Gryziński, M A; Kowalska, M; Meronka, K; Tulik, P

    2014-10-01

    Central Laboratory for Radiological Protection is involved in achieving scientific project on biological dosimetry. The project includes irradiation of blood samples in radiation fields of nuclear reactor. A simple facility for irradiation of biological samples has been prepared at horizontal channel of the nuclear reactor MARIA in NCBJ in Poland. The radiation field, composed mainly of gamma radiation and thermal neutrons, has been characterised in terms of tissue kerma using twin-detector technique and recombination chambers.

  2. Radiation-Hydromagnetic Models of a Z-Pinch Implosion with an Axial Magnetic Field

    NASA Astrophysics Data System (ADS)

    Clark, R. W.; Giuliani, J. L.; Terry, R.; Davis, J.; Velikovich, A. L.

    1997-11-01

    Experimental results on a 1MA pulser suggest that axial magnetic fields can stabilize z-pinch implosions and enhance the compression ratio(S. Sorokin and S. Chaikovsky, Dense Z-Pinches, AIP Conf. Proc. 299, p.83 (1993).). The present theoretical work calculates the effects of an axial magnetic field on the plasma and field profiles in an imploding z-pinch. The initial mass configuration is an annular shell of krypton. The 1-D simulation model includes: resistive diffusion (skin effect) for both the azimuthal and axial fields, ionization dynamics, and non-LTE radiation transport. Unlike the constant pulser current of self-similar models for the screw-pinch, a transmission line is used to model the circuit of a realistic ~10MA pulser. The implosion dynamics resulting from an axial field generated by a twisted return current cage will be compared with results due to an initial field from external Helmholtz coils. The dependence of the radiative performance on compression ratio, which in turn is a function of inital field strength or cage twist, will be discussed.

  3. A new multistack radiation boundary condition for FDTD based on self-teleportation of fields

    SciTech Connect

    Diaz, Rodolfo E.; Scherbatko, Igor . E-mail: igor_s@asu.edu

    2005-02-10

    In [Electromagnetics 23 (2003) 187], a technique for injecting perfect plane waves into finite regions of space in FDTD was reported. The essence of the technique, called Field Teleportation, is to invoke the principle of equivalent sources using FDTDs discrete definition of the curl to copy any field propagating in one FDTD domain to a finite region of another domain. In this paper, we apply this technique of Field Teleportation to the original domain itself to create a transparent boundary across which any outward traveling FDTD field produces an exact negative copy of itself. When this copied field is teleported one cell ahead and one cell forward in time it causes significant self-cancelation of the original field. Illustrative experiments in two-dimensions show that a two-layer (10-cell thick) multi-stack Radiation Boundary Condition (RBC) with a simplest Huygens's termination readily yields reflection coefficients of the order of -80 dB up to grazing incidence for all the fields radiated by a harmonic point source ({lambda} = 30 cells) in free space located 20 cells away from the boundary. Similarly low levels of artificial reflection are demonstrated for a case in which the RBC cuts through five different magnetodielectric materials.

  4. Complex Scattered Radiation Fields And Multiple Magnetic Fields In The Protostellar Cluster In NGC 2264

    NASA Astrophysics Data System (ADS)

    KWON, Jungmi; Tamura, M.; Kandori, R.; Kusakabe, N.; Hashimoto, J.; Nakajima, Y.; Nakamura, F.; Nagayama, T.; Nagata, T.; Hough, J. H.; Werner, M. W.; Teixeira, P. S.

    2012-05-01

    Near-infrared imaging polarimetry in the J, H, and Ks bands has been carried out for the protostellar cluster region around NGC 2264 IRS 2 in the Monoceros OB1 molecular cloud. Various infrared reflection nebula clusters (IRNCs) associated with NGC 2264 IRS 2 and the IRAS 12 S1 core, as well as local infrared reflection nebulae (IRNe), were detected. The illuminating sources of the IRNe were identified with known or new near- and mid-infrared sources. In addition, 314 point-like sources were detected in all three bands and their aperture polarimetry was studied. Using a color-color diagram, reddened field stars and diskless pre-main-sequence stars were selected to trace the magnetic field structure of the molecular cloud. The mean polarization position angle of the point-like sources is 80 degrees in the cluster core, and 60 degrees in the perimeter of the cluster core, which is interpreted as the projected direction on the sky of the magnetic field in the observed region of the cloud. The Chandrasekhar-Fermi method gives a rough estimate of the magnetic field strength to be about 100 micro-Gauss. A comparison with recent numerical simulations of the cluster formation implies that the cloud dynamics is controlled by the relatively strong magnetic field. The local magnetic field direction is well associated with that of CO outflow for IRAS 12 S1 and consistent with that inferred from submillimeter polarimetry. In contrast, the local magnetic field direction runs roughly perpendicular to the Galactic magnetic field direction.

  5. Assessment of radiation-induced second cancer risks in proton therapy and IMRT for organs inside the primary radiation field.

    PubMed

    Paganetti, Harald; Athar, Basit S; Moteabbed, Maryam; A Adams, Judith; Schneider, Uwe; Yock, Torunn I

    2012-10-07

    There is clinical evidence that second malignancies in radiation therapy occur mainly within the beam path, i.e. in the medium or high-dose region. The purpose of this study was to assess the risk for developing a radiation-induced tumor within the treated volume and to compare this risk for proton therapy and intensity-modulated photon therapy (IMRT). Instead of using data for specific patients we have created a representative scenario. Fully contoured age- and gender-specific whole body phantoms (4 year and 14 year old) were uploaded into a treatment planning system and tumor volumes were contoured based on patients treated for optic glioma and vertebral body Ewing's sarcoma. Treatment plans for IMRT and proton therapy treatments were generated. Lifetime attributable risks (LARs) for developing a second malignancy were calculated using a risk model considering cell kill, mutation, repopulation, as well as inhomogeneous organ doses. For standard fractionation schemes, the LAR for developing a second malignancy from radiation therapy alone was found to be up to 2.7% for a 4 year old optic glioma patient treated with IMRT considering a soft-tissue carcinoma risk model only. Sarcoma risks were found to be below 1% in all cases. For a 14 year old, risks were found to be about a factor of 2 lower. For Ewing's sarcoma cases the risks based on a sarcoma model were typically higher than the carcinoma risks, i.e. LAR up to 1.3% for soft-tissue sarcoma. In all cases, the risk from proton therapy turned out to be lower by at least a factor of 2 and up to a factor of 10. This is mainly due to lower total energy deposited in the patient when using proton beams. However, the comparison of a three-field and four-field proton plan also shows that the distribution of the dose, i.e. the particular treatment plan, plays a role. When using different fractionation schemes, the estimated risks roughly scale with the total dose difference in%. In conclusion, proton therapy can

  6. Formation of macroscopic surface layers on Fe(0) electrocoagulation electrodes during an extended field trial of arsenic treatment.

    PubMed

    van Genuchten, Case M; Bandaru, Siva R S; Surorova, Elena; Amrose, Susan E; Gadgil, Ashok J; Peña, Jasquelin

    2016-06-01

    Extended field trials to remove arsenic (As) via Fe(0) electrocoagulation (EC) have demonstrated consistent As removal from groundwater to concentrations below 10 μg L(-1). However, the coulombic performance of long-term EC field operation is lower than that of laboratory-based systems. Although EC electrodes used over prolonged periods show distinct passivation layers, which have been linked to decreased treatment efficiency, the spatial distribution and mineralogy of such surface layers have not been investigated. In this work, we combine wet chemical measurements with sub-micron-scale chemical maps and selected area electron diffraction (SAED) to determine the chemical composition and mineral phase of surface layers formed during long-term Fe(0) EC treatment. We analyzed Fe(0) EC electrodes used for 3.5 months of daily treatment of As-contaminated groundwater in rural West Bengal, India. We found that the several mm thick layer that formed on cathodes and anodes consisted of primarily magnetite, with minor fractions of goethite. Spatially-resolved SAED patterns also revealed small quantities of CaCO3, Mn oxides, and SiO2, the source of which was the groundwater electrolyte. We propose that the formation of the surface layer contributes to decreased treatment performance by preventing the migration of EC-generated Fe(II) to the bulk electrolyte, where As removal occurs. The trapped Fe(II) subsequently increases the surface layer size at the expense of treatment efficiency. Based on these findings, we discuss several simple and affordable methods to prevent the efficiency loss due to the surface layer, including alternating polarity cycles and cleaning the Fe(0) surface mechanically or via electrolyte scouring.

  7. Extended-gate field-effect transistor packed in micro channel for glucose, urea and protein biomarker detection.

    PubMed

    Lin, Yen-Heng; Chu, Chih-Pin; Lin, Chen-Fu; Liao, Hsin-Hao; Tsai, Hann-Huei; Juang, Ying-Zong

    2015-12-01

    This study developed a packaging method to integrate the extended-gate field-effect transistor (EGFET) into a microfluidic chip as a biological sensor. In addition, we present two immobilization approaches for the bio-recognition that are appropriate to this chip, allowing it to measure the concentrations of hydrogen ions, glucose, urea, and specific proteins in a solution. Alginate-calcium microcubes were used to embed the enzymes and magnetic powder (enzyme carrier). When the sensing chip needs the enzyme for the catalytic reaction, the alginate microcubes containing the corresponding enzymes enter through the flow channel and are immobilized on the EGFET surface with an external magnet. High sensing performance of the chip is achieved, with 37.45 mV/mM for measuring hydrogen ions at pH 6-8 with a linearity of 0.9939, 7.00 mV/mM for measuring glucose with a linearity of 0.9962, and 8.01 mV/mM for measuring urea with a linearity of 0.9809. In addition, based on the principle of the immunoassay, the magnetic beads with the specific antibody were used to capture the target protein in the sample. Then, negatively charged DNA fragments bound to a secondary antibody were used to amplify the signal for EGFET measurement. The magnetic beads with completed immune response bonding were then fixed on the surface of the sensor by an external magnetic field. Therefore, the measured object can directly contact the sensor surface, and quantitative detection of the protein concentration can be achieved. Apolipoprotein A1 (APOA1) was detected as a target protein, with a minimum detection limit of approximately 12.5 ng/mL.

  8. Zinc Oxide Nanorods Grown on Printed Circuit Board for Extended-Gate Field-Effect Transistor pH Sensor

    NASA Astrophysics Data System (ADS)

    Van Thanh, Pham; Nhu, Le Thi Quynh; Mai, Hong Hanh; Tuyen, Nguyen Viet; Doanh, Sai Cong; Viet, Nguyen Canh; Kien, Do Trung

    2017-02-01

    Zinc oxide (ZnO) nanorods (NRs) were grown directly on printed circuit boards with a 35-μm-thick copper layer using a seedless galvanic-cell hydrothermal process. The hexagonal structure of the synthesized ZnO NRs was observed by scanning electron microscopy. The microstructural characteristics of the as-grown ZnO NRs were investigated by x-ray diffraction analysis, revealing preferred (002) growth direction. Raman and photoluminescence spectra confirmed the high crystalline quality of the ZnO NRs. As-grown ZnO NRs were then grown for 7 h using the galvanic effect for use as the pH membrane of an extended-gate field-effect transistor pH sensor (pH-EGFET). The current-voltage characteristics showed sensitivity of 15.4 mV/pH and 0.26 (μA)1/2/pH in the linear and saturated region, respectively. Due to their cost effectiveness, low-temperature processing, and ease of fabrication, such devices are potential candidates for use as flexible, low-cost, disposable biosensors.

  9. An efficient and stable hybrid extended Lagrangian/self-consistent field scheme for solving classical mutual induction

    SciTech Connect

    Albaugh, Alex; Demerdash, Omar; Head-Gordon, Teresa

    2015-11-07

    We have adapted a hybrid extended Lagrangian self-consistent field (EL/SCF) approach, developed for time reversible Born Oppenheimer molecular dynamics for quantum electronic degrees of freedom, to the problem of classical polarization. In this context, the initial guess for the mutual induction calculation is treated by auxiliary induced dipole variables evolved via a time-reversible velocity Verlet scheme. However, we find numerical instability, which is manifested as an accumulation in the auxiliary velocity variables, that in turn results in an unacceptable increase in the number of SCF cycles to meet even loose convergence tolerances for the real induced dipoles over the course of a 1 ns trajectory of the AMOEBA14 water model. By diagnosing the numerical instability as a problem of resonances that corrupt the dynamics, we introduce a simple thermostating scheme, illustrated using Berendsen weak coupling and Nose-Hoover chain thermostats, applied to the auxiliary dipole velocities. We find that the inertial EL/SCF (iEL/SCF) method provides superior energy conservation with less stringent convergence thresholds and a correspondingly small number of SCF cycles, to reproduce all properties of the polarization model in the NVT and NVE ensembles accurately. Our iEL/SCF approach is a clear improvement over standard SCF approaches to classical mutual induction calculations and would be worth investigating for application to ab initio molecular dynamics as well.

  10. THE VERY LARGE ARRAY 1.4 GHz SURVEY OF THE EXTENDED CHANDRA DEEP FIELD SOUTH: SECOND DATA RELEASE

    SciTech Connect

    Miller, Neal A.; Bonzini, Margherita; Mainieri, Vincenzo; Padovani, Paolo; Rosati, Piero; Fomalont, Edward B.; Kellermann, Kenneth I.; Tozzi, Paolo; Vattakunnel, Shaji

    2013-04-01

    Deep radio observations at 1.4 GHz for the Extended Chandra Deep Field South were performed in 2007 June through September and presented in a first data release. The survey was made using six separate pointings of the Very Large Array with over 40 hr of observation per pointing. In the current paper, we improve on the data reduction to produce a second data release (DR2) mosaic image. This DR2 image covers an area of about a third of a square degree, reaches a best rms sensitivity of 6 {mu}Jy, and has a typical sensitivity of 7.4 {mu}Jy per 2.''8 by 1.''6 beam. We also present a more comprehensive catalog, including sources down to peak flux densities of five or more times the local rms noise along with information on source sizes and relevant pointing data. We discuss in some detail the consideration of whether sources are resolved under the complication of a radio image created as a mosaic of separate pointings each suffering some degree of bandwidth smearing, and the accurate evaluation of the flux densities of such sources. Finally, the radio morphologies and optical/near-IR counterpart identifications are used to identify 17 likely multiple-component sources and arrive at a catalog of 883 radio sources, which is roughly double the number of sources contained in the first data release.

  11. The electric field changes and UHF radiations caused by the triggered lightning in Japan

    NASA Technical Reports Server (NTRS)

    Kawasaki, Zen-Ichiro; Kanao, Tadashi; Matsuura, Kenji; Nakano, Minoru; Horii, Kenji; Nakamura, Koichi

    1991-01-01

    In the rocket triggered lightning experiment of fiscal 1989, researchers observed electromagnetic field changes and UHF electromagnetic radiation accompanying rocket triggered lightning. It was found that no rapid changes corresponding to the return stroke of natural lightning were observed in the electric field changes accompanying rocket triggered lightning. However, continuous currents were present. In the case of rocket triggered lightning to the tower, electromagnetic field changes corresponding to the initiation of triggered lightning showed a bipolar pulse of a relatively large amplitude. In contrast, the rocket triggered lightning to the ground did not have such a bipolar pulse. The UHF radiation accompanying the rocket triggered lightning preceded the waveform portions corresponding to the first changes in electromagnetic fields. The number of isolated pulses in the UHF radiation showed a correlation with the time duration from rocket launching up to triggered lightning. The time interval between consecutive isolated pulses tended to get shorter with the passage of time, just like the stepped leaders of natural lightning.

  12. Simulation of Relativistic Shocks and Associated Radiation from Turbulent Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Niemiec, J.; Medvedev, M.; Zhang, B.; Hardee, P.; Mizuno, Y.; Nordlund, A.; Frederiksen, J.; Sol, H.; Pohl, M.; Hartmann, D. H.; Fishman, J. F.

    2009-01-01

    Plasma instabilities excited in collisionless shocks are responsible for particle acceleration. We have investigated the particle acceleration and shock structure associated with an unmagnetized relativistic electron-positron jet propagating into an unmagnetized electron-positron plasma. Cold jet electrons are thermalized and slowed while the ambient electrons are swept up to create a partially developed hydrodynamic-like shock structure. In the leading shock, electron density increases by a factor of about 3.5 in the simulation frame. Strong electromagnetic fields are generated in the trailing shock and provide an emission site. These magnetic fields contribute to the electron's transverse deflection behind the shock. The jitter'' radiation from deflected electrons in turbulent magnetic fields has different properties than synchrotron radiation, which is calculated in a uniform magnetic field. This jitter radiation may be important for understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets in general, and supernova remnants. New spectra based on simulations will be presented.

  13. Particle Acceleration and Radiation associated with Magnetic Field Generation from Relativistic Collisionless Shocks

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.; Hardee, P. E.; Richardson, G. A.; Preece, R. D.; Sol, H.; Fishman, G. J.

    2003-01-01

    Shock acceleration is an ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet front propagating through an ambient plasma with and without initial magnetic fields. We find only small differences in the results between no ambient and weak ambient magnetic fields. Simulations show that the Weibel instability created in the collisionless shock front accelerates particles perpendicular and parallel to the jet propagation direction. While some Fermi acceleration may occur at the jet front, the majority of electron acceleration takes place behind the jet front and cannot be characterized as Fermi acceleration. The simulation results show that this instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields, which contribute to the electron s transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  14. Impact of an external radiation field on handheld XRF measurements for nuclear forensics applications

    SciTech Connect

    Steeb, Jennifer L.; Mertz, Carol J.; Finck, Martha R.; Engelstad, Gary; Carney, Kevin P.; Chamberlain, David B.

    2015-03-28

    X-ray fluorescence (XRF) is an attractive technique for nuclear forensics applications. We evaluated a handheld, portable XRF device by applying an external radiation field (10 mR/h to 17 R/h) using two types of radiography sources: a 60Co radiography camera to observe effects from high-energy gamma emissions and an 192Ir radiography camera to observe effects from several low-energy gamma (0.604, 0.468, and 0.317 MeV) and decay daughter x-ray emissions. External radiation tests proved that radiation, in general, has a significant effect on the dead time or background at dose rates over 1 R/hr for both the 192Ir and 60Co sources.

  15. Performance analysis of a filtered wide field-of-view radiometer for earth radiation budget measurements

    NASA Technical Reports Server (NTRS)

    Cooper, J. E.; Luther, M. R.

    1978-01-01

    The proposed Earth Radiation Budget Satellite System (ERBSS) of the 1980's will include a wide field-of-view (WFOV) fixed axes earth radiator discriminator consisting of a shortwave channel and a total (unfiltered) channel. The broadband spectral isolation required for the shortwave channel is achieved by use of a hemispherical fused silica (Suprasil W) dome filter placed in front of a wire wound thermopile radiation detector. A description is presented of the thermal response of the single-fused silica dome filter in the ERBSS WFOV shortwave channel conceptual design and the impact of that response on the channel measurement. Results from design definition and performance analysis studies are included. Problems associated with achieving the desired levels of confidence in a high accuracy filtered, WFOV radiometer are discussed. Design approaches, ground calibration, and data reduction techniques which minimize measurement uncertainties are explained.

  16. Radiation hardening of MOS devices by boron. [for stabilizing gate threshold potential of field effect device

    NASA Technical Reports Server (NTRS)

    Danchenko, V. (Inventor)

    1974-01-01

    A technique is described for radiation hardening of MOS devices and specifically for stabilizing the gate threshold potential at room temperature of a radiation subjected MOS field-effect device with a semiconductor substrate, an insulating layer of oxide on the substrate, and a gate electrode disposed on the insulating layer. The boron is introduced within a layer of the oxide of about 100 A-300 A thickness immediately adjacent the semiconductor-insulator interface. The concentration of boron in the oxide layer is preferably maintained on the order of 10 to the 18th power atoms/cu cm. The technique serves to reduce and substantially annihilate radiation induced positive gate charge accumulations.

  17. Effects of radiation damping on the dynamics of electrons in ELI intensity laser fields

    NASA Astrophysics Data System (ADS)

    Harvey, Christopher; Marklund, Mattias

    2012-07-01

    An electron in the presence of a high intensity laser field, such as that anticipated at ELI, will be accelerated so strongly that its own radiation emission may significantly affect its motion. This opens up the possibility of testing experimentally the classical theory of radiation reaction in such a context. We therefore explore the effects of radiation damping on the dynamics of electrons in optical laser pulses. In the case of high intensities and high initial electron energies, the trajectories and net energy changes of the electrons are found to be significantly altered. These effects are found to become increasingly significant the closer one gets to a directly head on collision between the laser and electrons.

  18. Matching Intensity-Modulated Radiation Therapy to an Anterior Low Neck Field

    SciTech Connect

    Amdur, Robert J. Liu, Chihray; Li, Jonathan; Mendenhall, William; Hinerman, Russell

    2007-10-01

    When using intensity-modulated radiation therapy (IMRT) to treat head and neck cancer with the primary site above the level of the larynx, there are two basic options for the low neck lymphatics: to treat the entire neck with IMRT, or to match the IMRT plan to a conventional anterior 'low neck' field. In view of the potential advantages of using a conventional low neck field, it is important to look for ways to minimize or manage the problems of matching IMRT to a conventional radiotherapy field. Treating the low neck with a single anterior field and the standard larynx block decreases the dose to the larynx and often results in a superior IMRT plan at the primary site. The purpose of this article is to review the most applicable studies and to discuss our experience with implementing a technique that involves moving the position of the superior border of the low neck field several times during a single treatment fraction.

  19. Intense THz radiation produced in organic salt crystals for high-field applications

    NASA Astrophysics Data System (ADS)

    Vicario, C.; Ruchert, C.; Hauri, C. P.

    2013-03-01

    Organic stilbazolium salt crystals pumped by intense, ultrashort mid-infrared laser have been investigated for efficient THz generation by optical rectification. In this paper we present our latest results in view of the generation of single-cycle and high-field THz transient in the THz gap (0.1-10 THz). The organic rectifiers like DAST, OH1 and DSTMS combine extremely large optical susceptibility with excellent velocity matching between the infrared pump and the THz radiation. Our simple collinear conversion scheme provides THz beams with excellent focusing properties and single cycle electric field larger than 1.5 MV/cm and magnetic field strength beyond 0.5 Tesla. The source can potentially cover the full THz gap at field strength which is barely provided by other THz sources. The THz pulse is carrier-envelope phase stable and the polarity of the field can be easily inverted.

  20. Radiation sensitivity of graphene field effect transistors and other thin film architectures

    NASA Astrophysics Data System (ADS)

    Cazalas, Edward

    An important contemporary motivation for advancing radiation detection science and technology is the need for interdiction of nuclear and radiological materials, which may be used to fabricate weapons of mass destruction. The detection of such materials by nuclear techniques relies on achieving high sensitivity and selectivity to X-rays, gamma-rays, and neutrons. To be attractive in field deployable instruments, it is desirable for detectors to be lightweight, inexpensive, operate at low voltage, and consume low power. To address the relatively low particle flux in most passive measurements for nuclear security applications, detectors scalable to large areas that can meet the high absolute detection efficiency requirements are needed. Graphene-based and thin-film-based radiation detectors represent attractive technologies that could meet the need for inexpensive, low-power, size-scalable detection architectures, which are sensitive to X-rays, gamma-rays, and neutrons. The utilization of graphene to detect ionizing radiation relies on the modulation of graphene charge carrier density by changes in local electric field, i.e. the field effect in graphene. Built on the principle of a conventional field effect transistor, the graphene-based field effect transistor (GFET) utilizes graphene as a channel and a semiconducting substrate as an absorber medium with which the ionizing radiation interacts. A radiation interaction event that deposits energy within the substrate creates electron-hole pairs, which modify the electric field and modulate graphene charge carrier density. A detection event in a GFET is therefore measured as a change in graphene resistance or current. Thin (micron-scale) films can also be utilized for radiation detection of thermal neutrons provided nuclides with high neutron absorption cross section are present with appreciable density. Detection in thin-film detectors could be realized through the collection of charge carriers generated within the

  1. On The Stability of A General Magnetic Field Topology In Stellar Radiative Zones

    NASA Astrophysics Data System (ADS)

    Augustson, Kyle; Mathis, Stéphane; Strugarek, Antoine

    2016-10-01

    This paper provides a brief overview of the formation of stellar fossil magnetic fields and what potential instabilities may occur given certain configurations of the magnetic field. In particular, a purely magnetic instability can occur for poloidal, toroidal, and mixed poloidal-toroidal axisymmetric magnetic field configurations as originally studied in Tayler (1973), Markey & Tayler (1973), and Tayler (1980). However, most of the magnetic field configurations observed at the surface of massive stars are non- axisymmetric. Thus, extending earlier studies of the axisymmetric Tayler instability in spherical geometry (Goossens, 1980), we introduce a formulation for the global change in the potential energy contained in a convectively-stable region given an arbitrary Lagrangian perturbation, which permits the inclusion of both axisymmetric and non-axisymmetric magnetic fields. With this tool in hand, a path is shown by which more general stability criterion can be established.

  2. Simulation of Relativistic Shocks and Associated Radiation from Turbulent Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Niemiec, J.; Medvedev, M.; Zhang, B.; Hardee, P.; Nordlund, A.; Frederiksen, J.; Mizuno, Y.; Sol, H.; Pohl, M.; Hartmann, D. H.; Fishman, G. J.

    2011-01-01

    Using our new 3-D relativistic particle-in-cell (PIC) code, we investigated long-term particle acceleration associated with a relativistic electron-positron jet propagating in an unmagnetized ambient electron-positron plasma. The simulations were performed using a much longer simulation system than our previous simulations in order to investigate the full nonlinear stage of the Weibel instability and its particle acceleration mechanism. Cold jet electrons are thermalized and ambient electrons are accelerated in the resulting shocks. Acceleration of ambient electrons leads to a maximum ambient electron density three times larger than the original value as predicted by hydrodynamic compression. Behind the bow shock, in the jet shock, strong electromagnetic fields are generated. These fields may lead to time dependent afterglow emission. In order to go beyond the standard synchrotron model used in astrophysical objects we have used PIC simulations and calculated radiation based on first principles. We calculated radiation from electrons propagating in a uniform parallel magnetic field to verify the technique. We also used the technique to calculate emission from electrons based on simulations with a small system. We obtain spectra which are consistent with those generated from electrons propagating in turbulent magnetic fields. This turbulent magnetic field is similar to the magnetic field generated at an early nonlinear stage of the Weibel instability. A fully developed shock within a larger system may generate a jitter/synchrotron spectrum.

  3. Occupational radiation exposure history of Idaho Field Office Operations at the INEL

    SciTech Connect

    Horan, J.R.; Braun, J.B.

    1993-10-01

    An extensive review has been made of the occupational radiation exposure records of workers at the Idaho National Engineering Laboratory (INEL) over the period of 1951 through 1990. The focus has been on workers employed by contractors and employees of the Idaho Field Operations Office (ID) of the United States Department of Energy (USDOE) and does not include the Naval Reactors Facility (NRF), the Argonne National Laboratory (ANL), or other operations field offices at the INEL. The radiation protection guides have decreased from 15 rem/year to 5 rem/year in 1990 for whole body penetrating radiation exposure. During these 40 years of nuclear operations (in excess of 200,000 man-years of work), a total of twelve individuals involved in four accidents exceeded the annual guidelines for exposure; nine of these exposures were received during life saving efforts on January 3, 1961 following the SL-1 reactor accident which killed three military personnel. These exposures ranged from 8 to 27 rem. Only one individual has exceeded the annual whole body penetrating radiation protection guidelines in the last 29 years.

  4. A 3D radiative transfer framework . VII. Arbitrary velocity fields in the Eulerian frame

    NASA Astrophysics Data System (ADS)

    Seelmann, A. M.; Hauschildt, P. H.; Baron, E.

    2010-11-01

    Aims: A solution of the radiative-transfer problem in 3D with arbitrary velocity fields in the Eulerian frame is presented. The method is implemented in our 3D radiative transfer framework and used in the PHOENIX/3D code. It is tested by comparison to our well-tested 1D co-moving frame radiative transfer code, where the treatment of a monotonic velocity field is implemented in the Lagrangian frame. The Eulerian formulation does not need much additional memory and is useable on state-of-the-art computers, even large-scale applications with 1000's of wavelength points are feasible. Methods: In the Eulerian formulation of the problem, the photon is seen by the atom at a Doppler-shifted wavelength depending on its propagation direction, which leads to a Doppler-shifted absorption and emission. This leads to a different source function and a different Λ^* operator in the radiative transfer equations compared to the static case. Results: The results of the Eulerian 3D spherical calculations are compared to our well-tested 1D Lagrangian spherical calculations, the agreement is, up to vmax = 1 × 103 km s-1 very good. Test calculation in other geometries are also shown.

  5. Radiation tolerant compact image sensor using CdTe photodiode and field emitter array (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Masuzawa, Tomoaki; Neo, Yoichiro; Mimura, Hidenori; Okamoto, Tamotsu; Nagao, Masayoshi; Akiyoshi, Masafumi; Sato, Nobuhiro; Takagi, Ikuji; Tsuji, Hiroshi; Gotoh, Yasuhito

    2016-10-01

    A growing demand on incident detection is recognized since the Great East Japan Earthquake and successive accidents in Fukushima nuclear power plant in 2011. Radiation tolerant image sensors are powerful tools to collect crucial information at initial stages of such incidents. However, semiconductor based image sensors such as CMOS and CCD have limited tolerance to radiation exposure. Image sensors used in nuclear facilities are conventional vacuum tubes using thermal cathodes, which have large size and high power consumption. In this study, we propose a compact image sensor composed of a CdTe-based photodiode and a matrix-driven Spindt-type electron beam source called field emitter array (FEA). A basic principle of FEA-based image sensors is similar to conventional Vidicon type camera tubes, but its electron source is replaced from a thermal cathode to FEA. The use of a field emitter as an electron source should enable significant size reduction while maintaining high radiation tolerance. Current researches on radiation tolerant FEAs and development of CdTe based photoconductive films will be presented.

  6. Modelling emission turbulence-radiation interaction by using a hybrid flamelet/stochastic Eulerian field method

    NASA Astrophysics Data System (ADS)

    Consalvi, Jean-Louis

    2017-01-01

    The time-averaged Radiative Transfer Equation (RTE) introduces two unclosed terms, known as `absorption Turbulence Radiation Interaction (TRI)' and `emission TRI'. Emission TRI is related to the non-linear coupling between fluctuations of the absorption coefficient and fluctuations of the Planck function and can be described without introduction any approximation by using a transported PDF method. In this study, a hybrid flamelet/ Stochastic Eulerian Field Model is used to solve the transport equation of the one-point one-time PDF. In this formulation, the steady laminar flamelet model (SLF) is coupled to a joint Probability Density Function (PDF) of mixture fraction, enthalpy defect, scalar dissipation rate, and soot quantities and the PDF transport equation is solved by using a Stochastic Eulerian Field (SEF) method. Soot production is modeled by a semi-empirical model and the spectral dependence of the radiatively participating species, namely combustion products and soot, are computed by using a Narrow Band Correlated-k (NBCK) model. The model is applied to simulate an ethylene/methane turbulent jet flame burning in an oxygen-enriched environment. Model results are compared with the experiments and the effects of taken into account Emission TRI on flame structure, soot production and radiative loss are discussed.

  7. EM Modeling of Far-Field Radiation Patterns for Antennas on the GMA-TT UAV

    NASA Technical Reports Server (NTRS)

    Mackenzie, Anne I.

    2015-01-01

    To optimize communication with the Generic Modular Aircraft T-Tail (GMA-TT) unmanned aerial vehicle (UAV), electromagnetic (EM) simulations have been performed to predict the performance of two antenna types on the aircraft. Simulated far-field radiation patterns tell the amount of power radiated by the antennas and the aircraft together, taking into account blockage by the aircraft as well as radiation by conducting and dielectric portions of the aircraft. With a knowledge of the polarization and distance of the two communicating antennas, e.g. one on the UAV and one on the ground, and the transmitted signal strength, a calculation may be performed to find the strength of the signal travelling from one antenna to the other and to check that the transmitted signal meets the receiver system requirements for the designated range. In order to do this, the antenna frequency and polarization must be known for each antenna, in addition to its design and location. The permittivity, permeability, and geometry of the UAV components must also be known. The full-wave method of moments solution produces the appropriate dBi radiation pattern in which the received signal strength is calculated relative to that of an isotropic radiator.

  8. EM modeling of far-field radiation patterns for antennas on the GMA-TT UAV

    NASA Astrophysics Data System (ADS)

    Mackenzie, Anne I.

    2015-05-01

    To optimize communication with the Generic Modular Aircraft T-Tail (GMA-TT) unmanned aerial vehicle (UAV), electromagnetic (EM) simulations have been performed to predict the performance of two antenna types on the aircraft. Simulated far-field radiation patterns tell the amount of power radiated by the antennas and the aircraft together, taking into account blockage by the aircraft as well as radiation by conducting and dielectric portions of the aircraft. With a knowledge of the polarization and distance of the two communicating antennas, e.g. one on the UAV and one on the ground, and the transmitted signal strength, a calculation may be performed to find the strength of the signal travelling from one antenna to the other and to check that the transmitted signal meets the receiver system requirements for the designated range. In order to do this, the antenna frequency and polarization must be known for each antenna, in addition to its design and location. The permittivity, permeability, and geometry of the UAV components must also be known. The full-wave method of moments solution produces the appropriate dBi radiation pattern in which the received signal strength is calculated relative to that of an isotropic radiator.

  9. Advances in Quantifying the Radiative Effects of Aerosol Particles on Climate from Airborne Field Studies

    NASA Astrophysics Data System (ADS)

    Pilewskie, P.; Schmidt, K. S.; Coddington, O.; Bergstrom, R.; Redemann, J.

    2007-12-01

    In the fourth assessment report of the Intergovernmental Panel on Climate Change, large uncertainties persist in estimates of climate forcing by aerosol particles. One contributor to this uncertainty is the poorly quantified vertical distribution of solar radiation absorbed by aerosol particles, from the regional to global scale. Another is the spectral and spatial variability of surface albedo, an effect that can dominate the top-of-atmosphere perturbations due to aerosol scattering and absorption, particularly over land. Over the past three years a number of intensive airborne field experiments (ICARTT, MILAGRO, GoMACCS) have contributed significantly to our understanding of the impact of pollution outflow from urban-industrial centers on radiative forcing, using spectrally resolved radiometric measurements and novel observationally-based methods to derive forcing efficiency and flux divergence. We present an overview of some of the most significant advances in direct radiative forcing realized by these studies, and recommendations on where the greatest challenges remain. In addition we present findings from these experiments on the influence of aerosol particles on cloud radiative properties, a potentially greater effect but even more uncertain than direct radiative forcing.

  10. Durability and shielding performance of borated Ceramicrete coatings in beta and gamma radiation fields

    NASA Astrophysics Data System (ADS)

    Wagh, Arun S.; Sayenko, S. Yu.; Dovbnya, A. N.; Shkuropatenko, V. A.; Tarasov, R. V.; Rybka, A. V.; Zakharchenko, A. A.

    2015-07-01

    Ceramicrete™, a chemically bonded phosphate ceramic, was developed for nuclear waste immobilization and nuclear radiation shielding. Ceramicrete products are fabricated by an acid-base reaction between magnesium oxide and mono potassium phosphate. Fillers are used to impart desired properties to the product. Ceramicrete's tailored compositions have resulted in several commercial structural products, including corrosion- and fire-protection coatings. Their borated version, called Borobond™, has been studied for its neutron shielding capabilities and is being used in structures built for storage of nuclear materials. This investigation assesses the durability and shielding performance of borated Ceramicrete coatings when exposed to gamma and beta radiations to predict the composition needed for optimal shielding performance in a realistic nuclear radiation field. Investigations were conducted using experimental data coupled with predictive Monte Carlo computer model. The results show that it is possible to produce products for simultaneous shielding of all three types of nuclear radiations, viz., neutrons, gamma-, and beta-rays. Additionally, because sprayable Ceramicrete coatings exhibit excellent corrosion- and fire-protection characteristics on steel, this research also establishes an opportunity to produce thick coatings to enhance the shielding performance of corrosion and fire protection coatings for use in high radiation environment in nuclear industry.

  11. Angular momentum loss of primordial gas in Lyα radiation field

    NASA Astrophysics Data System (ADS)

    Yajima, Hidenobu; Khochfar, Sadegh

    2014-06-01

    We present results on the radiation drag exerted by an isotropic and homogeneous background of Lyα photons on neutral gas clouds orbiting within H II regions around Population III stars of different masses. The Doppler shift causes a frequency difference between photons moving in the direction of the cloud and opposite to it resulting in a net momentum loss of the cloud in the direction of motion. We find that half of the angular momentum of gas with vθ ≲ 20 km s-1 near (r ≲ 3 kpc) a Population III star of 120 M⊙ at z = 20 is lost within ˜106 yr. The radiation drag is a strong function of cloud velocity that peaks at v ˜ 20 km s-1 reflecting the frequency dependence of the photon cross-section. Clouds moving with velocities larger than ˜100 km s-1 lose their angular momentum on time-scales of ˜108 yr. At lower redshifts radiation drag becomes inefficient as the Lyα photon density in H II regions decreases by a factor (1 + z)3 and angular momentum is lost on time-scales ≳ 108 yr even for low-velocity clouds. Our results suggest that a sweet spot exists for the loss of angular momentum by radiation drag for gas clouds at z > 10 and with v ˜ 20 km s-1. Comparison to dynamical friction forces acting on typical gas clouds suggest that radiation drag is the dominant effect impacting the orbit. We propose that this effect can suppress the formation of extended gas discs in the first galaxies and help gas accretion near galactic centres and central black holes.

  12. Characterization of Radiation Fields in Biological Shields of Nuclear Power Plants for Assessing Concrete Degradation

    NASA Astrophysics Data System (ADS)

    Remec, Igor; Rosseel, Thomas M.; Field, Kevin G.; Le Pape, Yann

    2016-02-01

    Life extensions of nuclear power plants to 60 and potentially 80 years of operation have renewed interest in long-term material degradation. One material being considered is concrete, with a particular focus on radiation-induced effects. Based on the projected neutron fluence values (E > 0.1 MeV) in the concrete biological shields of the US pressurized water reactor fleet and the available data on radiation effects on concrete, some decrease in mechanical properties of concrete cannot be ruled out during extended operation beyond 60 years. An expansion of the irradiated concrete database and a reliable determination of relevant neutron fluence energy cutoff value are necessary to ensure reliable risk assessment for extended operation of nuclear power plants. Notice: This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC0500OR22725 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.

  13. Minimum radiation force target size for power measurements in focused ultrasonic fields with circular symmetry.

    PubMed

    Beissner, K

    2010-12-01

    The time-averaged ultrasonic power emitted by medical ultrasonic equipment is mostly measured using a radiation force balance, and the question of the necessary target size is of practical importance. The question is answered here by calculations based on a Rayleigh integral algorithm for fields from circular, focusing transducers. This case occurs particularly in the field of high-intensity therapeutic ultrasound. The calculation yields the necessary size of an absorbing target so that the radiation force is 98% of that exerted on an absorber of infinite lateral size, and this as a function of the transducer-to-target distance, of the transducer radius in comparison with the wavelength and of the focus (half-)angle. Several distributions of the transducer vibration amplitude are considered. The Rayleigh integral strictly applies only to planar transducers, but among the amplitude distributions there is also one that allows the simulation of the spherically curved transducer type often found in practice.

  14. Electron-beam dynamics in a strong laser field including quantum radiation reaction

    NASA Astrophysics Data System (ADS)

    Neitz, N.; Di Piazza, A.

    2014-08-01

    The evolution of an electron beam colliding head on with a strong plane-wave field is investigated in the framework of strong-field QED including radiation-reaction effects due to photon emission. Employing a kinetic approach to describe the electron and the photon distribution it is shown that at a given total laser fluence the final electron distribution depends on the shape of the laser envelope and on the pulse duration, in contrast to the classical predictions of radiation reaction based on the Landau-Lifshitz equation. Finally, it is investigated how the pair-creation process leads to a nonlinear coupled evolution of the electrons in the beam, of the produced charged particles, and of the emitted photons.

  15. Active Thermal Extraction and Temperature Sensing of Near-field Thermal Radiation

    PubMed Central

    Ding, D.; Kim, T.; Minnich, A. J.

    2016-01-01

    Recently, we proposed an active thermal extraction (ATX) scheme that enables thermally populated surface phonon polaritons to escape into the far-field. The concept is based on a fluorescence upconversion process that also occurs in laser cooling of solids (LCS). Here, we present a generalized analysis of our scheme using the theoretical framework for LCS. We show that both LCS and ATX can be described with the same mathematical formalism by replacing the electron-phonon coupling parameter in LCS with the electron-photon coupling parameter in ATX. Using this framework, we compare the ideal efficiency and power extracted for the two schemes and examine the parasitic loss mechanisms. This work advances the application of ATX to manipulate near-field thermal radiation for applications such as temperature sensing and active radiative cooling. PMID:27595609

  16. Far-ultraviolet studies. VII - The spectrum and latitude dependence of the local interstellar radiation field

    NASA Technical Reports Server (NTRS)

    Henry, R. C.; Anderson, R. C.; Fastie, W. G.

    1980-01-01

    A direct measurement has been made of the spectrum (1180-1680 A) and Gould-latitude dependence of the local interstellar radiation field, over about one-third of the sky. The result is corrected to give expected values for the entire sky. The average local 1180-1680 A energy density is 5.8 x 10 to the -17th ergs/cu cm A. The surface brightness falls off toward high latitudes much more steeply than published models predict.

  17. On the relativistic classical motion of a radiating spinning particle in a magnetic field

    NASA Astrophysics Data System (ADS)

    Kar, Arnab; Rajeev, S. G.

    2011-04-01

    We propose classical equations of motion for a charged particle with magnetic moment, taking radiation reaction into account. This generalizes the Landau-Lifshitz equations for the spinless case. In the special case of spin-polarized motion in a constant magnetic field (synchrotron motion) we verify that the particle does lose energy. Previous proposals did not predict dissipation of energy and also suffered from runaway solutions analogous to those of the Lorentz-Dirac equations of motion.

  18. Depth-of-field effects in wiggler radiation sources: Geometrical versus wave optics

    NASA Astrophysics Data System (ADS)

    Walker, Richard P.

    2017-02-01

    A detailed analysis is carried out of the optical properties of synchrotron radiation emitted by multipole wigglers, concentrating on the effective source size and brightness and the so-called "depth of field" effects, concerning which there has been some controversy in the literature. By comparing calculations made with both geometrical optics and wave optics methods we demonstrate that the two approaches are not at variance, and that the wave optics results tend towards those of geometrical optics under well-defined conditions.

  19. Extended sources radiation and laplace type integral representation: Application to wave propagation above and within layered media

    NASA Astrophysics Data System (ADS)

    Filippi, P. J. T.

    1983-11-01

    In has been shown that the sound field reflected by the plane boundary of a layered ground can always be described by a specularly reflected wave, and layer potentials. Despite its generality, this representation is not quite suitable for numerical computation. Dealing with a very simple case, Weyl, and later on Ingard and Thomasson, proposed a representation of the solution in which the layer potential terms are replaced by the sum of surface wave and a Laplace type integral. Such an integral is very convenient for numerical purposes. In this paper, it is shown that this kind of representation can be obtained for a very wide class of sound propagation problems above or within layered media: a half-space bounded by a locally reacting surface, a finite layer of porous medium, a porous medium with depth-varying porosity, a thin elastic plate; wave propagation in shallow water with an impedance bottom. Many other applications could be developed.

  20. Pion production via proton synchrotron radiation in strong magnetic fields in relativistic field theory: Scaling relations and angular distributions

    SciTech Connect

    Maruyama, Tomoyuki; Cheoun, Myung-Ki; Kajino, Toshitaka; Mathews, Grant J.

    2016-03-26

    We study pion production by proton synchrotron radiation in the presence of a strong magnetic field when the Landau numbers of the initial and final protons are n(i, f) similar to 10(4)-10(5). We find in our relativistic field theory calculations that the pion decay width depends only on the field strength parameter which previously was only conjectured based upon semi-classical arguments. Moreover, we also find new results that the decay width satisfies a robust scaling relation, and that the polar angular distribution of emitted pion momenta is very narrow and can be easily obtained. This scaling implies that one can infer the decay width in more realistic magnetic fields of 10(15) G, where n(i, f) similar to 10(12)-10(13), from the results for n(i, f) similar to 10(4)-10(5). The resultant pion intensity and angular distributions for realistic magnetic field strengths are presented and their physical implications discussed. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).