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Sample records for helicity selection rule

  1. Evasion of helicity selection rule in χc1→VV and χc2→VP via intermediate charmed meson loops

    International Nuclear Information System (INIS)

    Liu Xiaohai; Zhao Qiang

    2010-01-01

    The hadronic decays of χ c1 →VV and χ c2 →VP are supposed to be suppressed by the helicity selection rule in the perturbative QCD framework. With an effective Lagrangian method, we show that the intermediate charmed meson loops can provide a mechanism for the evasion of the helicity selection rule, and result in sizeable decay branching ratios in some of those channels. The theoretical predictions can be examined by the forthcoming BES-III data in the near future.

  2. Observation of the helicity-selection-rule suppressed decay of the χc 2 charmonium state

    Science.gov (United States)

    Ablikim, M.; Achasov, M. N.; Ahmed, S.; Ai, X. C.; Albayrak, O.; Albrecht, M.; Ambrose, D. J.; Amoroso, A.; An, F. F.; An, Q.; Bai, J. Z.; Bakina, O.; Baldini Ferroli, R.; Ban, Y.; Bennett, D. W.; Bennett, J. V.; Berger, N.; Bertani, M.; Bettoni, D.; Bian, J. M.; Bianchi, F.; Boger, E.; Boyko, I.; Briere, R. A.; Cai, H.; Cai, X.; Cakir, O.; Calcaterra, A.; Cao, G. F.; Cetin, S. A.; Chai, J.; Chang, J. F.; Chelkov, G.; Chen, G.; Chen, H. S.; Chen, J. C.; Chen, M. L.; Chen, S.; Chen, S. J.; Chen, X.; Chen, X. R.; Chen, Y. B.; Chu, X. K.; Cibinetto, G.; Dai, H. L.; Dai, J. P.; Dbeyssi, A.; Dedovich, D.; Deng, Z. Y.; Denig, A.; Denysenko, I.; Destefanis, M.; de Mori, F.; Ding, Y.; Dong, C.; Dong, J.; Dong, L. Y.; Dong, M. Y.; Dou, Z. L.; Du, S. X.; Duan, P. F.; Fan, J. Z.; Fang, J.; Fang, S. S.; Fang, X.; Fang, Y.; Farinelli, R.; Fava, L.; Feldbauer, F.; Felici, G.; Feng, C. Q.; Fioravanti, E.; Fritsch, M.; Fu, C. D.; Gao, Q.; Gao, X. L.; Gao, Y.; Gao, Z.; Garzia, I.; Goetzen, K.; Gong, L.; Gong, W. X.; Gradl, W.; Greco, M.; Gu, M. H.; Gu, Y. T.; Guan, Y. H.; Guo, A. Q.; Guo, L. B.; Guo, R. P.; Guo, Y.; Guo, Y. P.; Haddadi, Z.; Hafner, A.; Han, S.; Hao, X. Q.; Harris, F. A.; He, K. L.; Heinsius, F. H.; Held, T.; Heng, Y. K.; Holtmann, T.; Hou, Z. L.; Hu, C.; Hu, H. M.; Hu, T.; Hu, Y.; Huang, G. S.; Huang, J. S.; Huang, X. T.; Huang, X. Z.; Huang, Z. L.; Hussain, T.; Ikegami Andersson, W.; Ji, Q.; Ji, Q. P.; Ji, X. B.; Ji, X. L.; Jiang, L. W.; Jiang, X. S.; Jiang, X. Y.; Jiao, J. B.; Jiao, Z.; Jin, D. P.; Jin, S.; Johansson, T.; Julin, A.; Kalantar-Nayestanaki, N.; Kang, X. L.; Kang, X. S.; Kavatsyuk, M.; Ke, B. C.; Kiese, P.; Kliemt, R.; Kloss, B.; Kolcu, O. B.; Kopf, B.; Kornicer, M.; Kupsc, A.; Kühn, W.; Lange, J. S.; Lara, M.; Larin, P.; Leithoff, H.; Leng, C.; Li, C.; Li, Cheng; Li, D. M.; Li, F.; Li, F. Y.; Li, G.; Li, H. B.; Li, H. J.; Li, J. C.; Li, Jin; Li, K.; Li, K.; Li, Lei; Li, P. R.; Li, Q. Y.; Li, T.; Li, W. D.; Li, W. G.; Li, X. L.; Li, X. N.; Li, X. Q.; Li, Y. B.; Li, Z. B.; Liang, H.; Liang, Y. F.; Liang, Y. T.; Liao, G. R.; Lin, D. X.; Liu, B.; Liu, B. J.; Liu, C. X.; Liu, D.; Liu, F. H.; Liu, Fang; Liu, Feng; Liu, H. B.; Liu, H. H.; Liu, H. H.; Liu, H. M.; Liu, J.; Liu, J. B.; Liu, J. P.; Liu, J. Y.; Liu, K.; Liu, K. Y.; Liu, L. D.; Liu, P. L.; Liu, Q.; Liu, S. B.; Liu, X.; Liu, Y. B.; Liu, Y. Y.; Liu, Z. A.; Liu, Zhiqing; Loehner, H.; Long, Y. F.; Lou, X. C.; Lu, H. J.; Lu, J. G.; Lu, Y.; Lu, Y. P.; Luo, C. L.; Luo, M. X.; Luo, T.; Luo, X. L.; Lyu, X. R.; Ma, F. C.; Ma, H. L.; Ma, L. L.; Ma, M. M.; Ma, Q. M.; Ma, T.; Ma, X. N.; Ma, X. Y.; Ma, Y. M.; Maas, F. E.; Maggiora, M.; Malik, Q. A.; Mao, Y. J.; Mao, Z. P.; Marcello, S.; Messchendorp, J. G.; Mezzadri, G.; Min, J.; Min, T. J.; Mitchell, R. E.; Mo, X. H.; Mo, Y. J.; Morales Morales, C.; Muchnoi, N. Yu.; Muramatsu, H.; Musiol, P.; Nefedov, Y.; Nerling, F.; Nikolaev, I. B.; Ning, Z.; Nisar, S.; Niu, S. L.; Niu, X. Y.; Olsen, S. L.; Ouyang, Q.; Pacetti, S.; Pan, Y.; Patteri, P.; Pelizaeus, M.; Peng, H. P.; Peters, K.; Pettersson, J.; Ping, J. L.; Ping, R. G.; Poling, R.; Prasad, V.; Qi, H. R.; Qi, M.; Qian, S.; Qiao, C. F.; Qin, L. Q.; Qin, N.; Qin, X. S.; Qin, Z. H.; Qiu, J. F.; Rashid, K. H.; Redmer, C. F.; Ripka, M.; Rong, G.; Rosner, Ch.; Ruan, X. D.; Sarantsev, A.; Savrié, M.; Schnier, C.; Schoenning, K.; Shan, W.; Shao, M.; Shen, C. P.; Shen, P. X.; Shen, X. Y.; Sheng, H. Y.; Song, W. M.; Song, X. Y.; Sosio, S.; Spataro, S.; Sun, G. X.; Sun, J. F.; Sun, S. S.; Sun, X. H.; Sun, Y. J.; Sun, Y. Z.; Sun, Z. J.; Sun, Z. T.; Tang, C. J.; Tang, X.; Tapan, I.; Thorndike, E. H.; Tiemens, M.; Uman, I.; Varner, G. S.; Wang, B.; Wang, B. L.; Wang, D.; Wang, D. Y.; Wang, K.; Wang, L. L.; Wang, L. S.; Wang, M.; Wang, P.; Wang, P. L.; Wang, W.; Wang, W. P.; Wang, X. F.; Wang, Y.; Wang, Y. D.; Wang, Y. F.; Wang, Y. Q.; Wang, Z.; Wang, Z. G.; Wang, Z. H.; Wang, Z. Y.; Wang, Z. Y.; Weber, T.; Wei, D. H.; Weidenkaff, P.; Wen, S. P.; Wiedner, U.; Wolke, M.; Wu, L. H.; Wu, L. J.; Wu, Z.; Xia, L.; Xia, L. G.; Xia, Y.; Xiao, D.; Xiao, H.; Xiao, Z. J.; Xie, Y. G.; Xie, Y. H.; Xiu, Q. L.; Xu, G. F.; Xu, J. J.; Xu, L.; Xu, Q. J.; Xu, Q. N.; Xu, X. P.; Yan, L.; Yan, W. B.; Yan, W. C.; Yan, Y. H.; Yang, H. J.; Yang, H. X.; Yang, L.; Yang, Y. X.; Ye, M.; Ye, M. H.; Yin, J. H.; You, Z. Y.; Yu, B. X.; Yu, C. X.; Yu, J. S.; Yuan, C. Z.; Yuan, Y.; Yuncu, A.; Zafar, A. A.; Zeng, Y.; Zeng, Z.; Zhang, B. X.; Zhang, B. Y.; Zhang, C. C.; Zhang, D. H.; Zhang, H. H.; Zhang, H. Y.; Zhang, J.; Zhang, J. J.; Zhang, J. L.; Zhang, J. Q.; Zhang, J. W.; Zhang, J. Y.; Zhang, J. Z.; Zhang, K.; Zhang, L.; Zhang, S. Q.; Zhang, X. Y.; Zhang, Y.; Zhang, Y.; Zhang, Y. H.; Zhang, Y. N.; Zhang, Y. T.; Zhang, Yu; Zhang, Z. H.; Zhang, Z. P.; Zhang, Z. Y.; Zhao, G.; Zhao, J. W.; Zhao, J. Y.; Zhao, J. Z.; Zhao, Lei; Zhao, Ling; Zhao, M. G.; Zhao, Q.; Zhao, Q. W.; Zhao, S. J.; Zhao, T. C.; Zhao, Y. B.; Zhao, Z. G.; Zhemchugov, A.; Zheng, B.; Zheng, J. P.; Zheng, W. J.; Zheng, Y. H.; Zhong, B.; Zhou, L.; Zhou, X.; Zhou, X. K.; Zhou, X. R.; Zhou, X. Y.; Zhu, K.; Zhu, K. J.; Zhu, S.; Zhu, S. H.; Zhu, X. L.; Zhu, Y. C.; Zhu, Y. S.; Zhu, Z. A.; Zhuang, J.; Zotti, L.; Zou, B. S.; Zou, J. H.; Besiii Collaboration

    2017-12-01

    The decays of χc 2→K+K-π0, KSK±π∓, and π+π-π0 are studied with the ψ (3686 ) data samples collected with the Beijing Spectrometer (BESIII). For the first time, the branching fractions of χc 2→K*K ¯, χc 2→a2±(1320 )π∓/a20(1320 )π0 , and χc 2→ρ (770 )±π∓ are measured. Here, K*K ¯ denotes both K*±K∓ and its isospin-conjugated process K*0K¯ 0+c .c . , and K* denotes the resonances K*(892 ), K2*(1430 ), and K3*(1780 ). The observations indicate a strong violation of the helicity selection rule in χc 2 decays into vector and pseudoscalar meson pairs. The measured branching fractions of χc 2→K*(892 )K ¯ are more than ten times larger than the upper limit of χc 2→ρ (770 )±π∓, which is so far the first direct observation of a significant U -spin symmetry breaking effect in charmonium decays.

  3. THE EFFECTS OF SPATIAL SMOOTHING ON SOLAR MAGNETIC HELICITY PARAMETERS AND THE HEMISPHERIC HELICITY SIGN RULE

    Energy Technology Data Exchange (ETDEWEB)

    Ocker, Stella Koch [Department of Physics, Oberlin College, Oberlin, OH 44074 (United States); Petrie, Gordon, E-mail: socker@oberlin.edu, E-mail: gpetrie@nso.edu [National Solar Observatory, Boulder, CO 80303 (United States)

    2016-12-01

    The hemispheric preference for negative/positive helicity to occur in the northern/southern solar hemisphere provides clues to the causes of twisted, flaring magnetic fields. Previous studies on the hemisphere rule may have been affected by seeing from atmospheric turbulence. Using Hinode /SOT-SP data spanning 2006–2013, we studied the effects of two spatial smoothing tests that imitate atmospheric seeing: noise reduction by ignoring pixel values weaker than the estimated noise threshold, and Gaussian spatial smoothing. We studied in detail the effects of atmospheric seeing on the helicity distributions across various field strengths for active regions (ARs) NOAA 11158 and NOAA 11243, in addition to studying the average helicities of 179 ARs with and without smoothing. We found that, rather than changing trends in the helicity distributions, spatial smoothing modified existing trends by reducing random noise and by regressing outliers toward the mean, or removing them altogether. Furthermore, the average helicity parameter values of the 179 ARs did not conform to the hemisphere rule: independent of smoothing, the weak-vertical-field values tended to be negative in both hemispheres, and the strong-vertical-field values tended to be positive, especially in the south. We conclude that spatial smoothing does not significantly affect the overall statistics for space-based data, and thus seeing from atmospheric turbulence seems not to have significantly affected previous studies’ ground-based results on the hemisphere rule.

  4. Selection rules for splitting strings

    NARCIS (Netherlands)

    Achucarro, A; Gregory, R

    1997-01-01

    It has been pointed out that Nielsen-Olesen vortices may be able to decay by pair production of black holes. We show that when the Abelian-Higgs model is embedded in a larger theory, the additional fields mau lead to selection rules for this process-even in the absence of fermions-due to the failure

  5. Selective decay in a helicity-injected spheromak

    International Nuclear Information System (INIS)

    MartInez, P L Garcia; Farengo, R

    2009-01-01

    The non-linear evolution of several unstable equilibria, representative of helicity-injected spheromak configurations inside a cylindrical flux conserver, is studied by means of three dimensional resistive MHD simulations. These equilibria are force-free (∇ x B = λ(ψ)B) but do not correspond to minimum energy states, having linear λ(ψ) profiles with negative slope. Several aspects of this process are studied (magnetic energy relaxation, selective helicity decay, relaxed profiles) for different initial A slopes. The stability threshold predicted by linear theory is recovered. The results show that complete plasma relaxation leading to a uniform A, is achieved only if the initial profile is hollow enough. The evolution for cases just above the stability threshold is more gentle and does not end in a Taylor state. The final state in these cases has a linear λ(ψ) profile, as the initial condition, but with a smaller slope.

  6. ON THE STRENGTH OF THE HEMISPHERIC RULE AND THE ORIGIN OF ACTIVE-REGION HELICITY

    International Nuclear Information System (INIS)

    Wang, Y.-M.

    2013-01-01

    Vector magnetograph and morphological observations have shown that the solar magnetic field tends to have negative (positive) helicity in the northern (southern) hemisphere, although only ∼60%-70% of active regions appear to obey this 'hemispheric rule'. In contrast, at least ∼80% of quiescent filaments and filament channels that form during the decay of active regions follow the rule. We attribute this discrepancy to the difficulty in determining the helicity sign of newly emerged active regions, which are dominated by their current-free component; as the transverse field is canceled at the polarity inversion lines, however, the axial component becomes dominant there, allowing a more reliable determination of the original active-region chirality. We thus deduce that the hemispheric rule is far stronger than generally assumed, and cannot be explained by stochastic processes. Earlier studies have shown that the twist associated with the axial tilt of active regions is too small to account for the observed helicity; here, both tilt and twist are induced by the Coriolis force acting on the diverging flow in the emerging flux tube. However, in addition to this east-west expansion about the apex of the loop, each of its legs must expand continually in cross section during its rise through the convection zone, thereby acquiring a further twist through the Coriolis force. Since this transverse pressure effect is not limited by drag or tension forces, the final twist depends mainly on the rise time, and may be large enough to explain the observed active-region helicity

  7. Continuum model for chiral induced spin selectivity in helical molecules

    Energy Technology Data Exchange (ETDEWEB)

    Medina, Ernesto [Centro de Física, Instituto Venezolano de Investigaciones Científicas, 21827, Caracas 1020 A (Venezuela, Bolivarian Republic of); Groupe de Physique Statistique, Institut Jean Lamour, Université de Lorraine, 54506 Vandoeuvre-les-Nancy Cedex (France); Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287 (United States); González-Arraga, Luis A. [IMDEA Nanoscience, Cantoblanco, 28049 Madrid (Spain); Finkelstein-Shapiro, Daniel; Mujica, Vladimiro [Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287 (United States); Berche, Bertrand [Centro de Física, Instituto Venezolano de Investigaciones Científicas, 21827, Caracas 1020 A (Venezuela, Bolivarian Republic of); Groupe de Physique Statistique, Institut Jean Lamour, Université de Lorraine, 54506 Vandoeuvre-les-Nancy Cedex (France)

    2015-05-21

    A minimal model is exactly solved for electron spin transport on a helix. Electron transport is assumed to be supported by well oriented p{sub z} type orbitals on base molecules forming a staircase of definite chirality. In a tight binding interpretation, the spin-orbit coupling (SOC) opens up an effective π{sub z} − π{sub z} coupling via interbase p{sub x,y} − p{sub z} hopping, introducing spin coupled transport. The resulting continuum model spectrum shows two Kramers doublet transport channels with a gap proportional to the SOC. Each doubly degenerate channel satisfies time reversal symmetry; nevertheless, a bias chooses a transport direction and thus selects for spin orientation. The model predicts (i) which spin orientation is selected depending on chirality and bias, (ii) changes in spin preference as a function of input Fermi level and (iii) back-scattering suppression protected by the SO gap. We compute the spin current with a definite helicity and find it to be proportional to the torsion of the chiral structure and the non-adiabatic Aharonov-Anandan phase. To describe room temperature transport, we assume that the total transmission is the result of a product of coherent steps.

  8. Catalysis by nonmetals rules for catalyst selection

    CERN Document Server

    Krylov, Oleg V

    1970-01-01

    Catalysis by Non-metals: Rules of Catalyst Selection presents the development of scientific principles for the collection of catalysts. It discusses the investigation of the mechanism of chemosorption and catalysis. It addresses a series of properties of solid with catalytic activity. Some of the topics covered in the book are the properties of a solid and catalytic activity in oxidation-reduction reactions; the difference of electronegativities and the effective charges of atoms; the role of d-electrons in the catalytic properties of a solid; the color of solids; and proton-acid and proton-ba

  9. Amplification of chirality in helical supramolecular polymers: the majority-rules principle.

    NARCIS (Netherlands)

    Gestel, van J.A.M.

    2004-01-01

    Amplification of chirality, being a strongly nonlinear response of the optical activity of helical polymers to a small (net) amount of optically active material, has recently been discovered in supramolecular copolymers. Apart from the sergeants-and-soldiers type we discussed in earlier work,

  10. Selection and application of C18200 chrome copper for the OHTE confinement test helical coil

    International Nuclear Information System (INIS)

    Puhn, F.A.; Graumann, D.W.

    1981-01-01

    The selection and qualification of copper for the OHTE confinement test helical coil (H-coil) was a crucial step in the success of this new experiment. Previous problems encountered at General Atomic Company with close tolerance machined parts made from high strength copper were identified. The design criteria included selecting a material with minimal warpage during machining, an electrical conductivity >80% IACS, and a yield strength of at least 241 Mpa (35 ksi). The investigation of candidate materials and testing samples led to selection of a material that fully met all requirements. The C18200 chrome copper forged plates were supplied by the Ampco Metal Division of Ampco-Pittsburgh Corporation

  11. Helix-sense-selective co-precipitation for preparing optically active helical polymer nanoparticles/graphene oxide hybrid nanocomposites.

    Science.gov (United States)

    Huang, Huajun; Li, Weifei; Shi, Yan; Deng, Jianping

    2017-05-25

    Constructing optically active helical polymer based nanomaterials without using expensive and limited chirally helical polymers has become an extremely attractive research topic in both chemical and materials science. In this study, we prepared a series of optically active helical polymer nanoparticles/graphene oxide (OAHPNs/GO) hybrid nanocomposites through an unprecedented strategy-the co-precipitation of optically inactive helical polymers and chirally modified GO. This approach is named helix-sense-selective co-precipitation (HSSCP), in which the chirally modified GO acted as a chiral source for inducing and further stabilizing the predominantly one-handed helicity in the optically inactive helical polymers. SEM and TEM images show quite similar morphologies of all the obtained OAHPNs/GO nanocomposites; specifically, the chirally modified GO sheets were uniformly decorated with spherical polymer nanoparticles. Circular dichroism (CD) and UV-vis absorption spectra confirmed the preferentially induced helicity in the helical polymers and the optical activity of the nanocomposites. The established HSSCP strategy is thus proven to be widely applicable and is expected to produce numerous functional OAHPNs/GO nanocomposites and even the analogues.

  12. Circular-Polarization-Selective Transmission Induced by Spin-Orbit Coupling in a Helical Tape Waveguide

    Science.gov (United States)

    Liu, Yahong; Guo, Qinghua; Liu, Hongchao; Liu, Congcong; Song, Kun; Yang, Biao; Hou, Quanwen; Zhao, Xiaopeng; Zhang, Shuang; Navarro-Cía, Miguel

    2018-05-01

    Spin-orbit coupling of light, describing the interaction between the polarization (spin) and spatial degrees of freedom (orbit) of light, plays an important role in subwavelength scale systems and leads to many interesting phenomena, such as the spin Hall effect of light. Here, based on the spin-orbit coupling, we design and fabricate a helical tape waveguide (HTW), which can realize a circular-polarization-selective process. When the incident circularly polarized wave is of the same handedness as the helix of the HTW, a nearly complete transmission is observed; in contrast, a counterrotating circular polarization of incident wave results in a much lower transmission or is even totally blocked by the HTW. Indeed, both simulations and experiments reveal that the blocked component of power leaks through the helical aperture of the HTW and forms a conical beam analogous to helical Cherenkov radiation due to the conversion from the spin angular momentum to the orbital angular momentum. Our HTW structure demonstrates its potential as a polarization selector in a broadband frequency range.

  13. Polarization Selectivity of Artificial Anisotropic Structures Based on DNA-Like Helices

    International Nuclear Information System (INIS)

    Semchenko, I. V.; Khakhomov, S. A.; Balmakov, A. P.

    2010-01-01

    Currently, 2D and 3D structures of different symmetries can be formed from DNA molecules. The electromagnetic properties of this new natural chiral material can be changed by metalizing DNA. Spatial structures of this type can be used in nanotechnology to prepare metamaterials for the far-UV region. It is shown by the example of an octahedron and a cube composed of DNA-like helices that these structures may exhibit polarization selectivity to electromagnetic radiation. In addition, it is suggested that the effect of the polarization selectivity of DNA-like artificial structures may also occur in the soft X-ray region for all living organisms in nature due to the universal DNA form.

  14. The Selective Autophagy Receptor p62 Forms a Flexible Filamentous Helical Scaffold

    Directory of Open Access Journals (Sweden)

    Rodolfo Ciuffa

    2015-05-01

    Full Text Available The scaffold protein p62/SQSTM1 is involved in protein turnover and signaling and is commonly found in dense protein bodies in eukaryotic cells. In autophagy, p62 acts as a selective autophagy receptor that recognizes and shuttles ubiquitinated proteins to the autophagosome for degradation. The structural organization of p62 in cellular bodies and the interplay of these assemblies with ubiquitin and the autophagic marker LC3 remain to be elucidated. Here, we present a cryo-EM structural analysis of p62. Together with structures of assemblies from the PB1 domain, we show that p62 is organized in flexible polymers with the PB1 domain constituting a helical scaffold. Filamentous p62 is capable of binding LC3 and addition of long ubiquitin chains induces disassembly and shortening of filaments. These studies explain how p62 assemblies provide a large molecular scaffold for the nascent autophagosome and reveal how they can bind ubiquitinated cargo.

  15. Learning a New Selection Rule in Visual and Frontal Cortex.

    Science.gov (United States)

    van der Togt, Chris; Stănişor, Liviu; Pooresmaeili, Arezoo; Albantakis, Larissa; Deco, Gustavo; Roelfsema, Pieter R

    2016-08-01

    How do you make a decision if you do not know the rules of the game? Models of sensory decision-making suggest that choices are slow if evidence is weak, but they may only apply if the subject knows the task rules. Here, we asked how the learning of a new rule influences neuronal activity in the visual (area V1) and frontal cortex (area FEF) of monkeys. We devised a new icon-selection task. On each day, the monkeys saw 2 new icons (small pictures) and learned which one was relevant. We rewarded eye movements to a saccade target connected to the relevant icon with a curve. Neurons in visual and frontal cortex coded the monkey's choice, because the representation of the selected curve was enhanced. Learning delayed the neuronal selection signals and we uncovered the cause of this delay in V1, where learning to select the relevant icon caused an early suppression of surrounding image elements. These results demonstrate that the learning of a new rule causes a transition from fast and random decisions to a more considerate strategy that takes additional time and they reveal the contribution of visual and frontal cortex to the learning process. © The Author 2016. Published by Oxford University Press.

  16. Introduction of helical computed tomography affects patient selection for V/Q lung scan

    International Nuclear Information System (INIS)

    Zettinig, G.; Baudrexel, S.; Leitha, Th.

    2002-01-01

    Aim: Retrospective analysis for determination of the effect of helical computed tomography (HCT) on utilization of V/Q lung scanning to diagnose pulmonary embolism (PE) in a large general hospital. Methods: A total number of 2676 V/Q scans of in- and out-patients referred to our department between March 1992 and December 1998 and between April 1997 and December 1998 were analyzed by an identical group of nuclear physicians. Results: Neither the total number of annually performed V/Q scans (446 ± 135) nor the mean age of patients (56 years ± 17) changed significantly since the introduction of HCT. However, the referral pattern was different. The percentage of patients with high and intermediate probability for PE decreased significantly from 15.2% to 9.4% (p <0.01) and from 10.2% to 7.3% (p <0.05), respectively. Low probability scans significantly increased from 37.8% to 42.7% (p <0.05). The percentage of normal scans did not change significantly, however, there was a highly significant increase summarizing patients with normal and low probability scans (74.6% to 83.3%; p <0.01). Conclusion: The introduction of HCT affected the selection of patients referred for V/Q lung scanning since V/Q scanning was primarily used to exclude rather to confirm PE. (orig.)

  17. A dosimetric selectivity intercomparison of HDR brachytherapy, IMRT and helical tomotherapy in prostate cancer radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Hermesse, Johanne; Biver, Sylvie; Jansen, Nicolas; Coucke, Philippe [Dept. of Radiation Oncology, Liege Univ. Hospital (Belgium); Lenaerts, Eric [Dept. of Medical Physics, Liege Univ. Hospital (Belgium); De Patoul, Nathalie; Vynckier, Stefaan [Dept. of Medical Physics, St Luc Univ. Hospital, Brussels (Belgium); Scalliet, Pierre [Dept. of Radiation Oncology, St Luc Univ. Hospital, Brussels (Belgium); Nickers, Philippe [Dept. of Radiation Oncology, Oscar Lambret Center, Lille (France)

    2009-11-15

    Background and purpose: dose escalation in order to improve the biochemical control in prostate cancer requires the application of irradiation techniques with high conformality. The dosimetric selectivity of three radiation modalities is compared: high-dose-rate brachytherapy (HDR-BT), intensity-modulated radiation radiotherapy (IMRT), and helical tomotherapy (HT). Patients and methods: ten patients with prostate adenocarcinoma treated by a 10-Gy HDR-BT boost after external-beam radiotherapy were investigated. For each patient, HDR-BT, IMRT and HT theoretical treatment plans were realized using common contour sets. A 10-Gy dose was prescribed to the planning target volume (PTV). The PTVs and critical organs' dose-volume histograms obtained were compared using Student's t-test. Results: HDR-BT delivers spontaneously higher mean doses to the PTV with smaller cold spots compared to IMRT and HT. 33% of the rectal volume received a mean HDR-BT dose of 3.86 {+-} 0.3 Gy in comparison with a mean IMRT dose of 6.57 {+-} 0.68 Gy and a mean HT dose of 5.58 {+-} 0.71 Gy (p < 0.0001). HDR-BT also enables to better spare the bladder. The hot spots inside the urethra are greater with HDR-BT. The volume of healthy tissue receiving 10% of the prescribed dose is reduced at least by a factor of 8 with HDR-BT (p < 0.0001). Conclusion: HDR-BT offers better conformality in comparison with HT and IMRT and reduces the volume of healthy tissue receiving a low dose. (orig.)

  18. On selection rules in vibrational and rotational molecular spectroscopy

    International Nuclear Information System (INIS)

    Guichardet, A.

    1986-01-01

    The aim of this work is a rigorous proof of the Selection Rules in Molecular Spectroscopy (Vibration and Rotation). To get this we give mathematically rigorous definitions of the (tensor) transition operators, in this case the electric dipole moment; this is done, firstly by considering the molecule as a set of point atomic kernels performing arbitrary motions, secondly by limiting ourselves either to infinitesimal vibration motions, or to arbitrary rotation motions. Then the selection rules follow from an abstract formulation of the Wigner-Eckart theorem. In a last paragraph we discuss the problem of separating vibration and rotation motions; very simple ideas from Differential Geometry, linked with the ''slice theorem'', allow us to define the relative speeds, the solid motions speeds, the Coriolis energies and the moving Eckart frames [fr

  19. Optimistic Selection Rule Better Than Majority Voting System

    Science.gov (United States)

    Sugiyama, Takuya; Obata, Takuya; Hoki, Kunihito; Ito, Takeshi

    A recently proposed ensemble approach to game-tree search has attracted a great deal of attention. The ensemble system consists of M computer players, where each player uses a different series of pseudo-random numbers. A combination of multiple players under the majority voting system would improve the performance of a Shogi-playing computer. We present a new strategy of move selection based on the search values of a number of players. The move decision is made by selecting one player from all M players. Each move is selected by referring to the evaluation value of the tree search of each player. The performance and mechanism of the strategy are examined. We show that the optimistic selection rule, which selects the player that yields the highest evaluation value, outperforms the majority voting system. By grouping 16 or more computer players straightforwardly, the winning rates of the strongest Shogi programs increase from 50 to 60% or even higher.

  20. Geometrical approach to central molecular chirality: a chirality selection rule

    OpenAIRE

    Capozziello, S.; Lattanzi, A.

    2004-01-01

    Chirality is of primary importance in many areas of chemistry and has been extensively investigated since its discovery. We introduce here the description of central chirality for tetrahedral molecules using a geometrical approach based on complex numbers. According to this representation, for a molecule having n chiral centres, it is possible to define an index of chirality. Consequently a chirality selection rule has been derived which allows the characterization of a molecule as achiral, e...

  1. Prospective comparison of helical CT with angiography in pulmonary embolism: global and selective vascular territory analysis. Interobserver agreement

    International Nuclear Information System (INIS)

    Ruiz, Yolanda; Caballero, Paloma; Caniego, Jose Luis; Friera, Alfonsa; Olivera, Maria Jose; Tagarro, David; Alvarez-Sala, Rodolfo

    2003-01-01

    The objective of this prospective study was to evaluate the sensitivity, specificity, positive and negative predictive values, and interobserver agreement in the diagnosis of pulmonary embolism with helical CT, compared with pulmonary angiography, for both global results and for selective vascular territories. Helical CT and pulmonary angiography were performed on 66 consecutive patients with clinical suspicion of pulmonary embolism. The exams were blindly interpreted by a vascular radiologist and by two independent thoracic radiologists. Results were analyzed for the final diagnosis as well as separately for 20 different arterial territories in each patient. Pulmonary angiography revealed embolism in 25 patients (38%); 48% were main, 28% lobar, 16% segmental, and 8% subsegmental. The sensitivity, specificity, and positive and negative predictive values of helical CT for observer 1 were, respectively, 91, 81.5, 75, and 94%; in 7.5% of the patients the exam was considered indeterminate. For observer 2 the values were, respectively, 88, 86, 81.5, and 91%; in 9% of the patients the exam was considered indeterminate. Main arteries were considered as non-valuable in 0-0.8%, the lobar in 1.5%, the segmental in 7.5-8.5%, and the subsegmental in 55-60%. Interobserver agreement for the final diagnosis was 80% (kappa 0.65). For each vascular territory, this was 98% (kappa 0.91) for main arteries, 92% (kappa 0.78) for lobar arteries, 79% (kappa 0.56) for segmental arteries, and 59% (kappa 0.21) for subsegmental arteries. Helical CT is a reliable method for pulmonary embolism diagnosis, with good interobserver agreement for main, lobar, and segmental territories. Worse results are found for subsegmental arteries, with high incidence of non-valuable branches and poor interobserver agreement. (orig.)

  2. Towards 'selection rules' in the radiation chemistry of molecular materials

    International Nuclear Information System (INIS)

    Feldman, V.I.; Inst. of Synthetic Polymetric Materials, Moscow; Moscow State Univ.

    2002-01-01

    Complete text of publication follows. There are a lot of experimental evidences suggesting that the primary radiation-induced events in organic solids and polymers are highly selective and sensitive to conformation, molecular packing, matrix environment, etc. Nevertheless, specific 'selection rules' in the radiation chemistry of molecules in solids are still not established. This contribution presents a review of our recent studies of the radiation damage in organic molecules in low-temperature matrices and polymers aimed at elucidation of basic physical factors controlling selectivity of the primary chemical events. The following aspects will be analyzed: 1. 'Fine tuning' effects in positive hole trapping in rigid systems containing molecular 'traps' with close ionization energy. 2. Selective chemical bond weakening in ionized molecules: experimental and theoretical results. 3. Matrix-assisted and matrix-controlled chemical reactions of ionized molecules in solid media (including the effect of 'matrix-catalysis'). 4. Effect of excess energy on the fate of ionized molecules in solid matrices: the role of intramolecular and intermolecular relaxation. Finally, the problem of experimental and theoretical simulation of the distribution of the radiation-induced events in complex molecular systems and polymers will be addressed

  3. Optical Selection Rule of Excitons in Gapped Chiral Fermion Systems

    Science.gov (United States)

    Zhang, Xiaoou; Shan, Wen-Yu; Xiao, Di

    2018-02-01

    We show that the exciton optical selection rule in gapped chiral fermion systems is governed by their winding number w , a topological quantity of the Bloch bands. Specifically, in a CN-invariant chiral fermion system, the angular momentum of bright exciton states is given by w ±1 +n N with n being an integer. We demonstrate our theory by proposing two chiral fermion systems capable of hosting dark s -like excitons: gapped surface states of a topological crystalline insulator with C4 rotational symmetry and biased 3 R -stacked MoS2 bilayers. In the latter case, we show that gating can be used to tune the s -like excitons from bright to dark by changing the winding number. Our theory thus provides a pathway to electrical control of optical transitions in two-dimensional material.

  4. Learning a New Selection Rule in Visual and Frontal Cortex

    NARCIS (Netherlands)

    van der Togt, Chris; Stănişor, Liviu; Pooresmaeili, Arezoo; Albantakis, Larissa; Deco, Gustavo; Roelfsema, Pieter R

    2016-01-01

    How do you make a decision if you do not know the rules of the game? Models of sensory decision-making suggest that choices are slow if evidence is weak, but they may only apply if the subject knows the task rules. Here, we asked how the learning of a new rule influences neuronal activity in the

  5. Alpha-helical hydrophobic polypeptides form proton-selective channels in lipid bilayers

    Science.gov (United States)

    Oliver, A. E.; Deamer, D. W.

    1994-01-01

    Proton translocation is important in membrane-mediated processes such as ATP-dependent proton pumps, ATP synthesis, bacteriorhodopsin, and cytochrome oxidase function. The fundamental mechanism, however, is poorly understood. To test the theoretical possibility that bundles of hydrophobic alpha-helices could provide a low energy pathway for ion translocation through the lipid bilayer, polyamino acids were incorporated into extruded liposomes and planar lipid membranes, and proton translocation was measured. Liposomes with incorporated long-chain poly-L-alanine or poly-L-leucine were found to have proton permeability coefficients 5 to 7 times greater than control liposomes, whereas short-chain polyamino acids had relatively little effect. Potassium permeability was not increased markedly by any of the polyamino acids tested. Analytical thin layer chromatography measurements of lipid content and a fluorescamine assay for amino acids showed that there were approximately 135 polyleucine or 65 polyalanine molecules associated with each liposome. Fourier transform infrared spectroscopy indicated that a major fraction of the long-chain hydrophobic peptides existed in an alpha-helical conformation. Single-channel recording in both 0.1 N HCl and 0.1 M KCl was also used to determine whether proton-conducting channels formed in planar lipid membranes (phosphatidylcholine/phosphatidylethanolamine, 1:1). Poly-L-leucine and poly-L-alanine in HCl caused a 10- to 30-fold increase in frequency of conductive events compared to that seen in KCl or by the other polyamino acids in either solution. This finding correlates well with the liposome observations in which these two polyamino acids caused the largest increase in membrane proton permeability but had little effect on potassium permeability. Poly-L-leucine was considerably more conductive than poly-L-alanine due primarily to larger event amplitudes and, to a lesser extent, a higher event frequency. Poly-L-leucine caused two

  6. Symmetry and optical selection rules in graphene quantum dots

    Science.gov (United States)

    Pohle, Rico; Kavousanaki, Eleftheria G.; Dani, Keshav M.; Shannon, Nic

    2018-03-01

    Graphene quantum dots (GQD's) have optical properties which are very different from those of an extended graphene sheet. In this paper, we explore how the size, shape, and edge structure of a GQD affect its optical conductivity. Using representation theory, we derive optical selection rules for regular-shaped dots, starting from the symmetry properties of the current operator. We find that, where the x and y components of the current operator transform with the same irreducible representation (irrep) of the point group (for example in triangular or hexagonal GQD's), the optical conductivity is independent of the polarization of the light. On the other hand, where these components transform with different irreps (for example in rectangular GQD's), the optical conductivity depends on the polarization of light. We carry out explicit calculations of the optical conductivity of GQD's described by a simple tight-binding model and, for dots of intermediate size, find an absorption peak in the low-frequency range of the spectrum which allows us to distinguish between dots with zigzag and armchair edges. We also clarify the one-dimensional nature of states at the Van Hove singularity in graphene, providing a possible explanation for very high exciton-binding energies. Finally, we discuss the role of atomic vacancies and shape asymmetry.

  7. Mode Selection Rule for Three-Delay Systems

    Science.gov (United States)

    Takahashi, Kin'ya; Kobayashi, Taizo

    2017-12-01

    We study the mode selection rule for a three-delay system to determine which oscillation mode is first excited by the Hopf bifurcation with increasing control parameter. We use linear stability analysis to detect an oscillating mode excited by the first bifurcation. There are two conditions, relevant and irrelevant conditions, determined by the ratios of three delay times, t1, t2, and tf, where tf is fixed and t1 and t2 are set as 0 < t1 < tf and 0 < t2 < tf. In a neighborhood of the relevant condition defined such that both t1/tf = n1/m1 and t2/tf = n2/m2 are ratios of odd to odd, oscillations nearly equal to the \\tilde{m}th-harmonic mode are excited, where \\tilde{m} is the least common multiple of m1 and m2. In the parameter space (t1,t2), there are irrelevant lines each of which is determined by a rational dependence of t1, t2, and tf, and does not allow any relevant condition. Extremely high order modes are observed along both sides of the irrelevant line. In particular, the line t2 = tf - t1, i.e., a diagonal with a slope of -1, shows the strongest irrelevancy.

  8. Cosmic selection rule for the glueball dark matter relic density

    Science.gov (United States)

    Soni, Amarjit; Xiao, Huangyu; Zhang, Yue

    2017-10-01

    We point out a unique mechanism to produce the relic abundance for the glueball dark matter from a gauged SU (N )d hidden sector which is bridged to the standard model sector through heavy vectorlike quarks colored under gauge interactions from both sides. A necessary ingredient of our assumption is that the vectorlike quarks, produced either thermally or nonthermally, are abundant enough to dominate the universe for some time in the early universe. They later undergo dark color confinement and form unstable vectorlike-quarkonium states which annihilate decay and reheat the visible and dark sectors. The ratio of entropy dumped into two sectors and the final energy budget in the dark glueballs is only determined by low energy parameters, including the intrinsic scale of the dark SU (N )d , Λd, and number of dark colors, Nd, but depend weakly on parameters in the ultraviolet such as the vectorlike quark mass or the initial condition. We call this a cosmic selection rule for the glueball dark matter relic density.

  9. Non-perturbative selection rules in F-theory

    Energy Technology Data Exchange (ETDEWEB)

    Martucci, Luca [Dipartimento di Fisica e Astronomia ‘Galileo Galilei’, Università di Padova, and I.N.F.N. Sezione di Padova, via Marzolo 8, Padova, I-35131 (Italy); Weigand, Timo [Institut für Theoretische Physik, Ruprecht-Karls-Universität, Philosophenweg 19, Heidelberg, 69120 (Germany)

    2015-09-29

    We discuss the structure of charged matter couplings in 4-dimensional F-theory compactifications. Charged matter is known to arise from M2-branes wrapping fibral curves on an elliptic or genus-one fibration Y. If a set of fibral curves satisfies a homological relation in the fibre homology, a coupling involving the states can arise without exponential volume suppression due to a splitting and joining of the M2-branes. If the fibral curves only sum to zero in the integral homology of the full fibration, no such coupling is possible. In this case an M2-instanton wrapping a 3-chain bounded by the fibral matter curves can induce a D-term which is volume suppressed. We elucidate the consequences of this pattern for the appearance of massive U(1) symmetries in F-theory and analyse the structure of discrete selection rules in the coupling sector. The weakly coupled analogue of said M2-instantons is worked out to be given by D1-F1 instantons. The generation of an exponentially suppressed F-term requires the formation of half-BPS bound states of M2 and M5-instantons. This effect and its description in terms of fluxed M5-instantons is discussed in a companion paper.

  10. Geometry Dynamics of α-Helices in Different Class I Major Histocompatibility Complexes

    Directory of Open Access Journals (Sweden)

    Reiner Ribarics

    2015-01-01

    Full Text Available MHC α-helices form the antigen-binding cleft and are of particular interest for immunological reactions. To monitor these helices in molecular dynamics simulations, we applied a parsimonious fragment-fitting method to trace the axes of the α-helices. Each resulting axis was fitted by polynomials in a least-squares sense and the curvature integral was computed. To find the appropriate polynomial degree, the method was tested on two artificially modelled helices, one performing a bending movement and another a hinge movement. We found that second-order polynomials retrieve predefined parameters of helical motion with minimal relative error. From MD simulations we selected those parts of α-helices that were stable and also close to the TCR/MHC interface. We monitored the curvature integral, generated a ruled surface between the two MHC α-helices, and computed interhelical area and surface torsion, as they changed over time. We found that MHC α-helices undergo rapid but small changes in conformation. The curvature integral of helices proved to be a sensitive measure, which was closely related to changes in shape over time as confirmed by RMSD analysis. We speculate that small changes in the conformation of individual MHC α-helices are part of the intrinsic dynamics induced by engagement with the TCR.

  11. New selection criteria for channel refueling of a Candu-6 reactor: introduction to floppy rules

    International Nuclear Information System (INIS)

    Brissette, D.

    2001-01-01

    A revised set of rules is in use at Gentilly-2 NGS for the selection of channels for refuelling. Traditional hard channel rejection rules (of go/no-go type) have been replaced by a more efficient set of soft evaluation rules based on concepts borrowed to the Fuzzy Logic. New evaluation rules, labelled as 'Floppy Rules', enable to assess and rate the channel suitability for refuelling by using a smooth and natural continuum of values qualifying excellent, good, fair and poor choices. Global channel suitability for refuelling is measured by combining separate ratings obtained from individual evaluation rules. Each evaluation rule is based on a specific control parameter related to local or lumped core properties. Two new software codes (NEWRULES and REFUEL) designed around the concept of Floppy Rules enable to perform a very efficient selection of optimized channel refuelling sequences either in manual and automatic mode. (author)

  12. Conformational Flexibility Determines Selectivity and Antibacterial, Antiplasmodial, and Anticancer Potency of Cationic α-Helical Peptides*

    OpenAIRE

    Vermeer, Louic S.; Lan, Yun; Abbate, Vincenzo; Ruh, Emrah; Bui, Tam T.; Wilkinson, Louise J.; Kanno, Tokuwa; Jumagulova, Elmira; Kozlowska, Justyna; Patel, Jayneil; McIntyre, Caitlin A.; Yam, W. C.; Siu, Gilman; Atkinson, R. Andrew; Lam, Jenny K. W.

    2012-01-01

    Background: Antimicrobial peptides (AMPs) have the potential to act against multiple pathogenic targets. Results: AMPs that maintain conformational flexibility are more potent against multiple pathogens and less hemolytic. Conclusion: Antimicrobial action and hemolysis proceed via differing mechanisms. Significance: The potency, selectivity, and ability of AMPs to reach intracellular pathogens can be modulated using general principles.

  13. A comparison of due-date selection rules

    NARCIS (Netherlands)

    Baker, K.R.; Bertrand, J.W.M.

    1981-01-01

    In sequencing and scheduling models it is usually assumed that due dates represent exogeneous information. In many practical settings, however, due dates can be discretionary, or at least negotiable. Relatively few studies have incorporated discretionary due dates, and even then the rules proposed

  14. Incorporating Employee Heterogeneity into Default Rules for Retirement Plan Selection

    Science.gov (United States)

    Goda, Gopi Shah; Manchester, Colleen Flaherty

    2013-01-01

    We study the effect of incorporating heterogeneity into default rules by examining the choice between retirement plans at a firm that transitioned from a defined benefit (DB) to a defined contribution (DC) plan. The default plan for existing employees varied discontinuously depending on their age. Employing regression discontinuity techniques,…

  15. Selection of the optimum magnet design for the International Linear Collider positron source helical undulator

    Directory of Open Access Journals (Sweden)

    D. J. Scott

    2007-03-01

    Full Text Available A comparison of possible undulator designs for the International Linear Collider positron source has resulted in a superconducting bifilar wire design being selected. After a comprehensive paper study and fabrication of the two preeminent designs, the superconducting undulator was chosen instead of the permanent magnet alternative. This was because of its superior performance in terms of magnetic field strength and quality, operational flexibility, risk of radiation damage, ease in achieving the required vacuum, and cost. The superconducting undulator design will now be developed into a complete system design for the full 200 m long magnet that is required.

  16. Advance Pricing Agreements and the Selectivity Criterion in EU State Aid Rules

    OpenAIRE

    Härö, O

    2017-01-01

    The Commission of the EU has recently decided that Advance Pricing Agreement rulings (the APA rulings) that Ireland, Luxembourg and the Netherlands have granted for Apple, Fiat and Starbucks (respectively) constitute illegal State aid according to Article 107 of the Treaty on the Functioning of the European Union (TFEU). The Commission claims that the APA rulings deviate from the arm´s length principle and that they grant economic benefit for the beneficiary undertakings in a selective manner...

  17. Optimisation or satiation, testing diet selection rules in goats

    NARCIS (Netherlands)

    Jansen, D.A.W.A.M.; Langevelde, van F.; Boer, de W.F.; Kirkman, K.P.

    2007-01-01

    Several hypotheses have been formulated to explain diet selection by herbivores, focusing on the maximization of nutrient intake, the minimization of plant secondary compounds, or the satiety hypothesis. This research aimed at studying diet selection revealing which chemical characteristics of

  18. Selective synthesis of double helices of carbon nanotube bundles grown on treated metallic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes-Sodi, Felipe; Iniguez-Rabago, Agustin; Rosas-Melendez, Samuel; Ballesteros-Villarreal, Monica [Departamento de Fisica y Matematicas, Universidad Iberoamericana, Prolongacion Paseo de la Reforma 880, Lomas de Santa Fe (Mexico); Vilatela, Juan J. [IMDEA Materials Institute, E.T.S. de Ingenieros de Caminos, Madrid (Spain); Reyes-Gutierrez, Lucio G.; Jimenez-Rodriguez, Jose A. [Ingenieria Industrial, Grupo JUMEX, Ecatepec de Morelos, Estado de Mexico (Mexico); Palacios, Eduardo [Lab. de Microscopia Electronica de Ultra Alta Resolucion, Instituto Mexicano del Petroleo, San Bartolo Atepehuacan (Mexico); Terrones, Mauricio [Department of Physics, Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University, University Park, PA (United States); Research Center for Exotic Nanocarbons (JST), Shinshu University, Nagano (Japan)

    2012-12-15

    Double-helix microstructures consisting of two parallel strands of hundreds of multi-walled carbon nanotubes (MWCNTs) have been synthesized by chemical vapour deposition of ferrocene/toluene vapours on metal substrates. Growth of coiled carbon nanostructures with site selectivity is achieved by varying the duration of thermochemical pretreatment to deposit a layer of SiO{sub x} on the metallic substrate. Production of multibranched structures of MWCNTs converging in SiO{sub x} microstructure is also reported. In the abstract figure, panel (a) shows a coloured micrograph of a typical double-helix coiled microstructure of MWCNTs grown on SiO{sub x} covered steel substrate. Green and blue show each of the two individual strands of MWCNTs. Panel (b) is an amplification of a SiO{sub x} microparticle (white) on the tip of the double-stranded coil (green and blue). The microparticle guides the collective growth of hundreds of MWCNTs to form the coiled structure. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Conformational Flexibility Determines Selectivity and Antibacterial, Antiplasmodial, and Anticancer Potency of Cationic α-Helical Peptides*

    Science.gov (United States)

    Vermeer, Louic S.; Lan, Yun; Abbate, Vincenzo; Ruh, Emrah; Bui, Tam T.; Wilkinson, Louise J.; Kanno, Tokuwa; Jumagulova, Elmira; Kozlowska, Justyna; Patel, Jayneil; McIntyre, Caitlin A.; Yam, W. C.; Siu, Gilman; Atkinson, R. Andrew; Lam, Jenny K. W.; Bansal, Sukhvinder S.; Drake, Alex F.; Mitchell, Graham H.; Mason, A. James

    2012-01-01

    We used a combination of fluorescence, circular dichroism (CD), and NMR spectroscopies in conjunction with size exclusion chromatography to help rationalize the relative antibacterial, antiplasmodial, and cytotoxic activities of a series of proline-free and proline-containing model antimicrobial peptides (AMPs) in terms of their structural properties. When compared with proline-free analogs, proline-containing peptides had greater activity against Gram-negative bacteria, two mammalian cancer cell lines, and intraerythrocytic Plasmodium falciparum, which they were capable of killing without causing hemolysis. In contrast, incorporation of proline did not have a consistent effect on peptide activity against Mycobacterium tuberculosis. In membrane-mimicking environments, structures with high α-helix content were adopted by both proline-free and proline-containing peptides. In solution, AMPs generally adopted disordered structures unless their sequences comprised more hydrophobic amino acids or until coordinating phosphate ions were added. Proline-containing peptides resisted ordering induced by either method. The roles of the angle subtended by positively charged amino acids and the positioning of the proline residues were also investigated. Careful positioning of proline residues in AMP sequences is required to enable the peptide to resist ordering and maintain optimal antibacterial activity, whereas varying the angle subtended by positively charged amino acids can attenuate hemolytic potential albeit with a modest reduction in potency. Maintaining conformational flexibility improves AMP potency and selectivity toward bacterial, plasmodial, and cancerous cells while enabling the targeting of intracellular pathogens. PMID:22869378

  20. Evaluation and Selection of Best Priority Sequencing Rule in Job Shop Scheduling using Hybrid MCDM Technique

    Science.gov (United States)

    Kiran Kumar, Kalla; Nagaraju, Dega; Gayathri, S.; Narayanan, S.

    2017-05-01

    Priority Sequencing Rules provide the guidance for the order in which the jobs are to be processed at a workstation. The application of different priority rules in job shop scheduling gives different order of scheduling. More experimentation needs to be conducted before a final choice is made to know the best priority sequencing rule. Hence, a comprehensive method of selecting the right choice is essential in managerial decision making perspective. This paper considers seven different priority sequencing rules in job shop scheduling. For evaluation and selection of the best priority sequencing rule, a set of eight criteria are considered. The aim of this work is to demonstrate the methodology of evaluating and selecting the best priority sequencing rule by using hybrid multi criteria decision making technique (MCDM), i.e., analytical hierarchy process (AHP) with technique for order preference by similarity to ideal solution (TOPSIS). The criteria weights are calculated by using AHP whereas the relative closeness values of all priority sequencing rules are computed based on TOPSIS with the help of data acquired from the shop floor of a manufacturing firm. Finally, from the findings of this work, the priority sequencing rules are ranked from most important to least important. The comprehensive methodology presented in this paper is very much essential for the management of a workstation to choose the best priority sequencing rule among the available alternatives for processing the jobs with maximum benefit.

  1. A Method for the Comparison of Item Selection Rules in Computerized Adaptive Testing

    Science.gov (United States)

    Barrada, Juan Ramon; Olea, Julio; Ponsoda, Vicente; Abad, Francisco Jose

    2010-01-01

    In a typical study comparing the relative efficiency of two item selection rules in computerized adaptive testing, the common result is that they simultaneously differ in accuracy and security, making it difficult to reach a conclusion on which is the more appropriate rule. This study proposes a strategy to conduct a global comparison of two or…

  2. Contracting Selection for the Development of the Range Rule Risk Methodology

    National Research Council Canada - National Science Library

    1997-01-01

    ...-Effectiveness Risk Tool and contractor selection for the development of the Range Rule Risk Methodology. The audit objective was to determine whether the Government appropriately used the Ordnance and Explosives Cost-Effectiveness Risk Tool...

  3. Selection rules for the dematerialization of a particle into two photons

    International Nuclear Information System (INIS)

    Yang, C.N.

    1983-01-01

    Selection rules governing the disintegration of a particle into two photons are derived from the general principle of invariance under rotation and inversion. The polarization state of the photons is completely fixed by the selection rules for initial particles with spin less than 2. These results which are independent of any specific assumption about the interactions may possibly offer a method of deciding the symmetry nature of mesons which decay into two photons. 4 tables

  4. Mode Selection Rules for a Two-Delay System with Positive and Negative Feedback Loops

    Science.gov (United States)

    Takahashi, Kin'ya; Kobayashi, Taizo

    2018-04-01

    The mode selection rules for a two-delay system, which has negative feedback with a short delay time t1 and positive feedback with a long delay time t2, are studied numerically and theoretically. We find two types of mode selection rules depending on the strength of the negative feedback. When the strength of the negative feedback |α1| (α1 0), 2m + 1-th harmonic oscillation is well sustained in a neighborhood of t1/t2 = even/odd, i.e., relevant condition. In a neighborhood of the irrelevant condition given by t1/t2 = odd/even or t1/t2 = odd/odd, higher harmonic oscillations are observed. However, if |α1| is slightly less than α2, a different mode selection rule works, where the condition t1/t2 = odd/even is relevant and the conditions t1/t2 = odd/odd and t1/t2 = even/odd are irrelevant. These mode selection rules are different from the mode selection rule of the normal two-delay system with two positive feedback loops, where t1/t2 = odd/odd is relevant and the others are irrelevant. The two types of mode selection rules are induced by individually different mechanisms controlling the Hopf bifurcation, i.e., the Hopf bifurcation controlled by the "boosted bifurcation process" and by the "anomalous bifurcation process", which occur for |α1| below and above the threshold value αth, respectively.

  5. Selection rule for Dirac-like points in two-dimensional dielectric photonic crystals

    KAUST Repository

    Li, Yan

    2013-01-01

    We developed a selection rule for Dirac-like points in two-dimensional dielectric photonic crystals. The rule is derived from a perturbation theory and states that a non-zero, mode-coupling integral between the degenerate Bloch states guarantees a Dirac-like point, regardless of the type of the degeneracy. In fact, the selection rule can also be determined from the symmetry of the Bloch states even without computing the integral. Thus, the existence of Dirac-like points can be quickly and conclusively predicted for various photonic crystals independent of wave polarization, lattice structure, and composition. © 2013 Optical Society of America.

  6. Supporting domain experts to select and configure precise compliance rules

    NARCIS (Netherlands)

    Ramezani, E.; Fahland, D.; Aalst, van der W.M.P.; Lohmann, N.; Song, M.; Wohed, P.

    2014-01-01

    Compliance specifications concisely describe selected aspects of what a business operation should adhere to. To enable automated techniques for compliance checking, it is important that these requirements are specified correctly and precisely, describing exactly the behavior intended. Although there

  7. Requirements for facilities transferring or receiving select agents. Final rule.

    Science.gov (United States)

    2001-08-31

    CDC administers regulations that govern the transfer of certain biological agents and toxins ("select agents"). These regulations require entities that transfer or receive select agents to register with CDC and comply with biosafety standards contained in the Third Edition of the CDC/NIH publication "Biosafety in Microbiological and Biomedical Laboratories ("BMBL")." On October 28,1999, CDC published a Notice of Proposed Rulemaking ("NPRM") seeking both to revise the biosafety standards facilities must follow when handling select agents and to provide new biosecurity standards for such facilities. These new standards are contained in the Fourth Edition of BMBL, which the NPRM proposed to incorporate by reference, thereby replacing the Third Edition. No comments were received in response to this proposal. CDC is therefore amending its regulations to incorporate the Fourth Edition.

  8. An assessment of heat transfer models of water flow in helically coiled tubes based on selected experimental datasets

    International Nuclear Information System (INIS)

    Gou, Junli; Ma, Haifu; Yang, Zijiang; Shan, Jianqiang

    2017-01-01

    Highlights: •A review of heat transfer characteristics for water flow in helically coiled tubes are conducted. •An assessment of heat transfer models under different heat transfer modes in helically coiled tubes are performed. •This work could provide references for the use of the correlations and for further studies. -- Abstract: This paper presents an assessment of the heat transfer models under different heat transfer modes for water flow in helically coiled tubes based on the compiled datasets from the reviewed literatures. For single phase flow, most of the correlations of the heat transfer coefficient can fit well to the experiments. The correlations of Xin-Ebadian, Dravid and Kalb-Seader for laminar flow and those of Seban-McLaughlim, Mori-Nakayama, Xin-Ebadian, Hardik, Rogers-Mayhew, Mikaila-Poskas and El-Genk-Schriener for turbulent flow are recommended. For flow boiling heat transfer, Steiner-Taborek correlation could be utilized to predict the boiling heat transfer coefficients in helically coiled tubes for a relatively wide range of parameters. For dryout quality, the correlations of Hwang et al. and Santini et al. give relatively better predictions than others. However, more accurate correlations for flow boiling heat transfer coefficient and dryout quality need to be developed based on further investigations with wider parameter ranges in the future. The present work could provide references for the investigators for future uses of those correlations and for performing further investigations on the heat transfer characteristics of water flow in helically coiled tubes.

  9. Rule-based versus probabilistic selection for active surveillance using three definitions of insignificant prostate cancer

    NARCIS (Netherlands)

    L.D.F. Venderbos (Lionne); M.J. Roobol-Bouts (Monique); C.H. Bangma (Chris); R.C.N. van den Bergh (Roderick); L.P. Bokhorst (Leonard); D. Nieboer (Daan); Godtman, R; J. Hugosson (Jonas); van der Kwast, T; E.W. Steyerberg (Ewout)

    2016-01-01

    textabstractTo study whether probabilistic selection by the use of a nomogram could improve patient selection for active surveillance (AS) compared to the various sets of rule-based AS inclusion criteria currently used. We studied Dutch and Swedish patients participating in the European Randomized

  10. Selection rules for electron transfer to the continuum in ion-atom collision

    Energy Technology Data Exchange (ETDEWEB)

    Barrachina, R.O.; Bernardi, G.C.; Garibotti, C.R.

    1985-10-01

    We consider the process of electron transfer to the in first order Born approximation. We analyse the expansion of the double-differential cross section in series of electron velocity and ejection angle. We found that the coefficients obey precise selection rules. We discuss the relation of these rules, which predict an asymmetric shape for the electron loss to the continuum cusp, with the interpretation of recent experimental results.

  11. Helical filaments

    Energy Technology Data Exchange (ETDEWEB)

    Barbieri, Nicholas; Lim, Khan; Durand, Magali; Baudelet, Matthieu; Richardson, Martin [Townes Laser Institute, CREOL—The College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816 (United States); Hosseinimakarem, Zahra; Johnson, Eric [Micro-Photonics Laboratory – Center for Optical Material Science, Clemson, Anderson, South Carolina 29634 (United States)

    2014-06-30

    The shaping of laser-induced filamenting plasma channels into helical structures by guiding the process with a non-diffracting beam is demonstrated. This was achieved using a Bessel beam superposition to control the phase of an ultrafast laser beam possessing intensities sufficient to induce Kerr effect driven non-linear self-focusing. Several experimental methods were used to characterize the resulting beams and confirm the observed structures are laser air filaments.

  12. Communication: The H2@C60 inelastic neutron scattering selection rule: Expanded and explained

    Science.gov (United States)

    Poirier, Bill

    2015-09-01

    Recently [M. Xu et al., J. Chem. Phys. 139, 064309 (2013)], an unexpected selection rule was discovered for the title system, contradicting the previously held belief that inelastic neutron scattering (INS) is not subject to any selection rules. Moreover, the newly predicted forbidden transitions, which emerge only in the context of coupled H2 translation-rotation (TR) dynamics, have been confirmed experimentally. However, a simple physical understanding, e.g., based on group theory, has been heretofore lacking. This is provided in the present paper, in which we (1) derive the correct symmetry group for the H2@C60 TR Hamiltonian and eigenstates; (2) complete the INS selection rule, and show that the set of forbidden transitions is actually much larger than previously believed; and (3) evaluate previous theoretical and experimental results, in light of the new findings.

  13. Plasma turbulence. Structure formation, selection rule, dynamic response and dynamics transport

    International Nuclear Information System (INIS)

    Ito, Sanae I.

    2010-01-01

    The five-year project of Grant-in-Aid for Specially Promoted Research entitled general research on the structure formation and selection rule in plasma turbulence had brought many outcomes. Based on these outcomes, the Grant-in-Aid for Scientific Research (S) program entitled general research on dynamic response and dynamic transport in plasma turbulence has started. In the present paper, the state-of-the-art of the research activities on the structure formation, selection rule and dynamics in plasma turbulence are reviewed with reference to outcomes of these projects. (author)

  14. Electrically-induced polarization selection rules of a graphene quantum dot

    Science.gov (United States)

    Dong, Qing-Rui; Li, Yan; Jia, Chen; Wang, Fu-Li; Zhang, Ya-Ting; Liu, Chun-Xiang

    2018-05-01

    We study theoretically the single-electron triangular zigzag graphene quantum dot in uniform in-plane electric fields. The absorption spectra of the dot are calculated by the tight-binding method. The energy spectra and the distribution of wave functions are also presented to analyse the absorption spectra. The orthogonal zero-energy eigenstates are arranged along to the direction of the external field. The remarkable result is that all intraband transitions and some interband transitions are forbidden when the absorbed light is polarized along the direction of the electric field. With x-direction electric field, all intraband absorption is y polarized due to the electric-field-direction-polarization selection rule. Moreover, with y-direction electric field, all absorption is either x or y polarized due to the parity selection rule as well as to the electric-field-direction-polarization selection rule. Our calculation shows that the formation of the absorption spectra is co-decided by the polarization selection rules and the overlap between the eigenstates of the transition.

  15. Optical absorption spectra of linear and cyclic thiophenes--selection rules manifestation

    International Nuclear Information System (INIS)

    Bednarz, Mariusz; Reineker, Peter; Mena-Osteritz, Elena; Baeuerle, Peter

    2004-01-01

    We theoretically study the size-dependent relation between absorption spectra of thiophene-based oligomers and the corresponding cyclothiophenes. In our approach based on a Frenkel exciton Hamiltonian, we demonstrate that the geometry and selection rules determine the observed relations between the spectra

  16. Selecting Pesticides and Nonchemical Alternatives: Green Thumbs' Rules of Thumb Decision Tools.

    Science.gov (United States)

    Grieshop, James I.; And Others

    1992-01-01

    A sample of 78 (of 320) home gardeners use rules of thumb (heuristics) to choose between chemical pesticides and nonchemical alternatives. Pesticides rank low in 24 choice attributes where alternatives rank high, and vice versa. Gender, age, and years of pesticide use correlate with pesticide selection. (SK)

  17. Bourdieu's Distinction between Rules and Strategies and Secondary Principal Practice: A Review of Selected Literature

    Science.gov (United States)

    Anderson, Karen

    2016-01-01

    This paper reviews a selection of literature on secondary principal practice from which to propose an approach for further research. The review demonstrates that applications of Bourdieu's theory of practice have contributed to understandings about secondary principal practice, and that the distinction he made between rules and strategies has the…

  18. HEMISPHERIC HELICITY TREND FOR SOLAR CYCLE 24

    International Nuclear Information System (INIS)

    Hao Juan; Zhang Mei

    2011-01-01

    Using vector magnetograms obtained with the Spectro-polarimeter (SP) on board Hinode satellite, we studied two helicity parameters (local twist and current helicity) of 64 active regions that occurred in the descending phase of solar cycle 23 and the ascending phase of solar cycle 24. Our analysis gives the following results. (1) The 34 active regions of the solar cycle 24 follow the so-called hemispheric helicity rule, whereas the 30 active regions of the solar cycle 23 do not. (2) When combining all 64 active regions as one sample, they follow the hemispheric helicity sign rule as in most other observations. (3) Despite the so-far most accurate measurement of vector magnetic field given by SP/Hinode, the rule is still weak with large scatters. (4) The data show evidence of different helicity signs between strong and weak fields, confirming previous result from a large sample of ground-based observations. (5) With two example sunspots we show that the helicity parameters change sign from the inner umbra to the outer penumbra, where the sign of penumbra agrees with the sign of the active region as a whole. From these results, we speculate that both the Σ-effect (turbulent convection) and the dynamo have contributed in the generation of helicity, whereas in both cases turbulence in the convection zone has played a significant role.

  19. New narrow boson resonances and SU(4) symmetry: Selection rules, SU(4) mixing, and mass formulas

    International Nuclear Information System (INIS)

    Takasugi, E.; Oneda, S.

    1975-01-01

    General SU(4) sum rules are obtained for bosons in the theoretical framework of asymptotic SU(4), chiral SU(4) direct-product SU(4) charge algebra, and a simple mechanism of SU(4) and chiral SU(4) direct-product SU(4) breaking. The sum rules exhibit a remarkable interplay of the masses, SU(4) mixing angles, and axial-vector matrix elements of 16-plet boson multiplets. Under a particular circumstance (i.e., in the ''ideal'' limit) this interplay produces selection rules which may explain the remarkable stability of the newly found narrow boson resonances. General SU(4) mass formulas and inter-SU(4) -multiplet mass relations are derived and SU(4) mixing parameters are completely determined. Ground state 1 -- and 0 -+ 16-plets are especially discussed and the masses of charmed and uncharmed new members of these multiplets are predicted

  20. Bilingualism trains specific brain circuits involved in flexible rule selection and application.

    Science.gov (United States)

    Stocco, Andrea; Prat, Chantel S

    2014-10-01

    Bilingual individuals have been shown to outperform monolinguals on a variety of tasks that measure non-linguistic executive functioning, suggesting that some facets of the bilingual experience give rise to generalized improvements in cognitive performance. The current study investigated the hypothesis that such advantage in executive functioning arises from the need to flexibly select and apply rules when speaking multiple languages. Such flexible behavior may strengthen the functioning of the fronto-striatal loops that direct signals to the prefrontal cortex. To test this hypothesis, we compared behavioral and brain data from proficient bilinguals and monolinguals who performed a Rapid Instructed Task Learning paradigm, which requires behaving according to ever-changing rules. Consistent with our hypothesis, bilinguals were faster than monolinguals when executing novel rules, and this improvement was associated with greater modulation of activity in the basal ganglia. The implications of these findings for language and executive function research are discussed herein. Published by Elsevier Inc.

  1. Forecasting Urban Air Quality via a Back-Propagation Neural Network and a Selection Sample Rule

    Directory of Open Access Journals (Sweden)

    Yonghong Liu

    2015-07-01

    Full Text Available In this paper, based on a sample selection rule and a Back Propagation (BP neural network, a new model of forecasting daily SO2, NO2, and PM10 concentration in seven sites of Guangzhou was developed using data from January 2006 to April 2012. A meteorological similarity principle was applied in the development of the sample selection rule. The key meteorological factors influencing SO2, NO2, and PM10 daily concentrations as well as weight matrices and threshold matrices were determined. A basic model was then developed based on the improved BP neural network. Improving the basic model, identification of the factor variation consistency was added in the rule, and seven sets of sensitivity experiments in one of the seven sites were conducted to obtain the selected model. A comparison of the basic model from May 2011 to April 2012 in one site showed that the selected model for PM10 displayed better forecasting performance, with Mean Absolute Percentage Error (MAPE values decreasing by 4% and R2 values increasing from 0.53 to 0.68. Evaluations conducted at the six other sites revealed a similar performance. On the whole, the analysis showed that the models presented here could provide local authorities with reliable and precise predictions and alarms about air quality if used at an operational scale.

  2. Code-specific learning rules improve action selection by populations of spiking neurons.

    Science.gov (United States)

    Friedrich, Johannes; Urbanczik, Robert; Senn, Walter

    2014-08-01

    Population coding is widely regarded as a key mechanism for achieving reliable behavioral decisions. We previously introduced reinforcement learning for population-based decision making by spiking neurons. Here we generalize population reinforcement learning to spike-based plasticity rules that take account of the postsynaptic neural code. We consider spike/no-spike, spike count and spike latency codes. The multi-valued and continuous-valued features in the postsynaptic code allow for a generalization of binary decision making to multi-valued decision making and continuous-valued action selection. We show that code-specific learning rules speed up learning both for the discrete classification and the continuous regression tasks. The suggested learning rules also speed up with increasing population size as opposed to standard reinforcement learning rules. Continuous action selection is further shown to explain realistic learning speeds in the Morris water maze. Finally, we introduce the concept of action perturbation as opposed to the classical weight- or node-perturbation as an exploration mechanism underlying reinforcement learning. Exploration in the action space greatly increases the speed of learning as compared to exploration in the neuron or weight space.

  3. Partner bands of 126Cs - first observation of chiral electromagnetic selection rules

    International Nuclear Information System (INIS)

    Grodner, E.; Sankowska, I.; Morek, T.; Rohozinski, S.G.; Droste, Ch.; Srebrny, J.; Pasternak, A.A.; Kisielinski, M.; Kowalczyk, M.; Kownacki, J.; Mierzejewski, J.; Krol, A.

    2011-01-01

    The lifetimes of the excited states belonging to the chiral partner bands built on the πh 11/2 xνh 11/2 -1 configuration in 126 Cs have been measured using the DSA technique. For the first time the large set of the experimental transition probabilities is in qualitative agreement with all selection rules predicted for the strong chiral symmetry breaking limit. The selection rules originate from two general features of a chiral nucleus, namely, from the existence of well separated left- and right-handed systems built of three angular momentum vectors and extra symmetries appearing in addition to the chiral symmetry breaking. The B(M1) staggering resulting from these additional symmetries is sensitive to triaxiality of odd-odd nuclei as well as configuration of valence particles.

  4. Modification of selection rules as a P-noninvariant effect in the charge-monopole system

    International Nuclear Information System (INIS)

    Tolkachev, E.A.; Tomil'chik, L.M.; Shnir, Y.M.

    1983-01-01

    It is shown that P-noninvariance in the theory of magnetic charge, connected with the non-removability of the discontinuity of the phase of the wave function of charged particles in the field of a Dirac monopole, leads to a change in the selection rules for dipole radiation, which can in principle be used as a critical test for a model with magnetically charged quarks

  5. Manifestation of Spin Selection Rules on the Quantum Tunneling of Magnetization in a Single Molecule Magnet

    OpenAIRE

    Henderson, J. J.; Koo, C.; Feng, P. L.; del Barco, E.; Hill, S.; Tupitsyn, I. S.; Stamp, P. C. E.; Hendrickson, D. N.

    2009-01-01

    We present low temperature magnetometry measurements on a new Mn3 single-molecule magnet (SMM) in which the quantum tunneling of magnetization (QTM) displays clear evidence for quantum mechanical selection rules. A QTM resonance appearing only at elevated temperatures demonstrates tunneling between excited states with spin projections differing by a multiple of three: this is dictated by the C3 symmetry of the molecule, which forbids pure tunneling from the lowest metastable state. Resonances...

  6. Symmetry-adaptation and selection rules for effective crystal field Hamiltonians

    International Nuclear Information System (INIS)

    Tuszynski, J.A.

    1986-01-01

    The intention of this paper is to systematically derive an effective Hamiltonian in the presence of crystal fields in such a way as to incorporate relativistic effects and higher order perturbation corrections including configuration mixing. This Hamiltonian will then be conveniently represented as a symmetry-adapted series of one- and two-body double tensor operators whose matrix elements will be analyzed for selection rules. 16 references, 4 tables

  7. Appropriateness guidelines and predictive rules to select patients for upper endoscopy: a nationwide multicenter study.

    Science.gov (United States)

    Buri, Luigi; Hassan, Cesare; Bersani, Gianluca; Anti, Marcello; Bianco, Maria Antonietta; Cipolletta, Livio; Di Giulio, Emilio; Di Matteo, Giovanni; Familiari, Luigi; Ficano, Leonardo; Loriga, Pietro; Morini, Sergio; Pietropaolo, Vincenzo; Zambelli, Alessandro; Grossi, Enzo; Intraligi, Marco; Buscema, Massimo

    2010-06-01

    Selecting patients appropriately for upper endoscopy (EGD) is crucial for efficient use of endoscopy. The objective of this study was to compare different clinical strategies and statistical methods to select patients for EGD, namely appropriateness guidelines, age and/or alarm features, and multivariate and artificial neural network (ANN) models. A nationwide, multicenter, prospective study was undertaken in which consecutive patients referred for EGD during a 1-month period were enrolled. Before EGD, the endoscopist assessed referral appropriateness according to the American Society for Gastrointestinal Endoscopy (ASGE) guidelines, also collecting clinical and demographic variables. Outcomes of the study were detection of relevant findings and new diagnosis of malignancy at EGD. The accuracy of the following clinical strategies and predictive rules was compared: (i) ASGE appropriateness guidelines (indicated vs. not indicated), (ii) simplified rule (>or=45 years or alarm features vs. <45 years without alarm features), (iii) logistic regression model, and (iv) ANN models. A total of 8,252 patients were enrolled in 57 centers. Overall, 3,803 (46%) relevant findings and 132 (1.6%) new malignancies were detected. Sensitivity, specificity, and area under the receiver-operating characteristic curve (AUC) of the simplified rule were similar to that of the ASGE guidelines for both relevant findings (82%/26%/0.55 vs. 88%/27%/0.52) and cancer (97%/22%/0.58 vs. 98%/20%/0.58). Both logistic regression and ANN models seemed to be substantially more accurate in predicting new cases of malignancy, with an AUC of 0.82 and 0.87, respectively. A simple predictive rule based on age and alarm features is similarly effective to the more complex ASGE guidelines in selecting patients for EGD. Regression and ANN models may be useful in identifying a relatively small subgroup of patients at higher risk of cancer.

  8. Raman selection rules and tensor elements for PMN-0.3PT single crystal

    International Nuclear Information System (INIS)

    Ge, Wanyin; Zhu, Wenliang; Pezzotti, Giuseppe

    2009-01-01

    Selection rules were put forward theoretically and Raman tensor elements experimentally determined for PMN-0.3PT single-crystal. Such a body of information was then employed to evaluate local domain orientation in a relaxor-based PMN-0.3PT material by means of polarized microprobe Raman spectroscopy. The dependence of Raman spectra upon crystal rotation under different polarized probe configurations was experimentally confirmed by collecting the intensity variation of selected Raman modes on Euler's angle rotation in a poled single-crystal. The periodicity of relative Raman intensity of selected Raman bands revealed symmetry properties. Upon exploiting such properties and with the knowledge of the Raman tensor elements from the A g and E g vibrational modes, a viable path becomes available to determine domain texture in relaxor-based PMN-PT materials with high spatial resolution. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Experimental study of selection rules following from the existence of two types of neutrinos

    International Nuclear Information System (INIS)

    Gaillard, J.M.

    1963-05-01

    Interactions of high energy neutrinos with matter have been observed In the course of an experiment done in collaboration with G. Danby, K. Goulianos, L. M. Lederman, N. Mistry, M. Schwartz and J. Steinberger at the Brookhaven AGS. The neutrinos were produced mainly in the decay π ± → μ ± + υ(υ-bar); the experiment leads to the conclusion that thee neutrinos are very likely different from the ones produced in beta decay reactions. We use the result of this experiment to study the selection rules applicable in the framework of a two neutrino theory. (author) [fr

  10. Helicity content and tokamak applications of helicity

    International Nuclear Information System (INIS)

    Boozer, A.H.

    1986-05-01

    Magnetic helicity is approximately conserved by the turbulence associated with resistive instabilities of plasmas. To generalize the application of the concept of helicity, the helicity content of an arbitrary bounded region of space will be defined. The definition has the virtues that both the helicity content and its time derivative have simple expressions in terms of the poloidal and toroidal magnetic fluxes, the average toroidal loop voltage and the electric potential on the bounding surface, and the volume integral of E-B. The application of the helicity concept to tokamak plasmas is illustrated by a discussion of so-called MHD current drive, an example of a stable tokamak q profile with q less than one in the center, and a discussion of the possibility of a natural steady-state tokamak due to the bootstrap current coupling to tearing instabilities

  11. A solution to the vertical barΔI/sup →/vertical bar = 1/2 rule and other dynamical selection rules in particle physics

    International Nuclear Information System (INIS)

    Oneda, S.; Terasaki, K.

    1984-01-01

    Algebraic approach is developed in the framework of QCD and Electroweak theories. It is stressed that many seemingly different dynamical selection rules can share the same origin. In particular, derivation of vertical bar Δ I → vertical bar = 1/2 rule and explicit identification of its small violation are made for the Κ → 2 π decays, using new much milder soft-pion extrapolation. As a byproduct, the Β → ωπ decays are predicted to be predominantly λ = +-1 transitions in consistency with experiment

  12. Complex Dynamics of Droplet Traffic in a Bifurcating Microfluidic Channel: Periodicity, Multistability, and Selection Rules

    Science.gov (United States)

    Sessoms, D. A.; Amon, A.; Courbin, L.; Panizza, P.

    2010-10-01

    The binary path selection of droplets reaching a T junction is regulated by time-delayed feedback and nonlinear couplings. Such mechanisms result in complex dynamics of droplet partitioning: numerous discrete bifurcations between periodic regimes are observed. We introduce a model based on an approximation that makes this problem tractable. This allows us to derive analytical formulae that predict the occurrence of the bifurcations between consecutive regimes, establish selection rules for the period of a regime, and describe the evolutions of the period and complexity of droplet pattern in a cycle with the key parameters of the system. We discuss the validity and limitations of our model which describes semiquantitatively both numerical simulations and microfluidic experiments.

  13. RULES FOR SELECTING AND USING KEY PERFORMANCE INDICATORS FOR THE SERVICE INDUSTRY

    Directory of Open Access Journals (Sweden)

    Alexandra - Elena RUSĂNEANU

    2014-06-01

    Full Text Available There is no question that performance is the desired result of every activity or action. In order to correctly measure an organization’s performance it is necessary to select key performance indicators (KPIs that will deliver long-term value to the company. KPIs are presenting performance information for all levels of the organization and they are reflecting the progress made so far to achieve strategic objectives. The selection of the key performance indicators must be made according to the organization’s industry and activity. The company must truly understand its business and its mission. Also, KPIs must be closely linked to the strategic objectives. The focus of this research is to present effective rules for defining key performance indicators for the Service industry. This sector of economy consists in generating intangible goods like experience, expertise and information. Therefore, monitoring this type of services requires a different approach when defining performance indicators compared to the manufacturing industry.

  14. Selection rule engineering of forbidden transitions of a hydrogen atom near a nanogap

    Science.gov (United States)

    Kim, Hyunyoung Y.; Kim, Daisik S.

    2018-01-01

    We perform an analytical study on the allowance of forbidden transitions for a hydrogen atom placed near line dipole sources, mimicking light emanating from a one-dimensional metallic nanogap. It is shown that the rapid variation of the electric field vector, inevitable in the near zone, completely breaks the selection rule of Δl=±1. While the forbidden transitions between spherically symmetric S states, such as 2S to 1S or 3S to 1S (Δl=0), are rather robust against selection rule breakage, Δl=±2 transitions such as between 3D and 1S or 3D and 2S states are very vulnerable to the spatial variation of the perturbing electric field. Transitions between 2S and 3D states are enhanced by many orders of magnitude, aided by the quadratic nature of both the perturbing Hamiltonian and D wavefunctions. The forbidden dipole moment, which approaches one Bohr radius times the electric charge in the vicinity of the gap, can be written in a simple closed form owing to the one-dimensional nature of our gap. With large enough effective volume together with the symmetric nature of the excited state wavefunctions, our work paves way towards atomic physics application of infinitely long nanogaps.

  15. Hidden selection rules, M5-instantons and fluxes in F-theory

    Energy Technology Data Exchange (ETDEWEB)

    Martucci, Luca [Dipartimento di Fisica e Astronomia ‘Galileo Galilei’, Università di Padova, & I.N.F.N. Sezione di Padova, via Marzolo 8, I-35131 Padova (Italy); Weigand, Timo [Institut für Theoretische Physik, Ruprecht-Karls-Universität, Philosophenweg 19, 69120 Heidelberg (Germany)

    2015-10-21

    We introduce a new approach to investigate the selection rules governing the contributions of fluxed M5-instantons to the F-theory four-dimensional effective action, with emphasis on the generation of charged matter F-terms. The structure of such couplings is unraveled by exploiting the perturbative and non-perturbative homological relations, introduced in our companion paper http://dx.doi.org/10.1007/JHEP09(2015)198, which encode the interplay between the self-dual 3-form flux on the M5-brane, the background 4-form flux and certain fibral curves. The latter are wrapped by time-like M2-branes representing matter insertions in the instanton path integral. In particular, we clarify how fluxed M5-instantons detect the presence of geometrically massive U(1)s which are responsible for ‘hidden’ selection rules. We discuss how for non-generic embeddings the M5-instanton can probe ‘locally massless’ U(1) symmetries if the rank of its Mordell-Weil group is enhanced compared to that of the bulk. As a phenomenological off-spring we propose a new type of non-perturbative corrections to Yukawa couplings which may change the rank of the Yukawa matrix. Along the way, we also gain new insights into the structure of massive U(1) gauge fluxes in the stable degeneration limit.

  16. Helical CT of ureteral disease

    International Nuclear Information System (INIS)

    Cikman, Pablo; Bengio, Ruben; Bulacio, Javier; Zirulnik, Esteban; Garimaldi, Jorge

    2000-01-01

    Among the new applications of helical CT is the study of the ureteral pathology. The objective of this paper was to evaluate patients with suspected pathology of this organ and the repercussion in the therapeutic plans. We studied 23 patients with a helical CT protocol, without IV contrast injection and performed multiplanar reconstruction (MPR). We called this procedure Pielo CT. Thirteen ureteral stones were detected, 6 calculi, 2 urinary tract tumors, dilatation of the system in a patient with neo-bladder. In 2 patients, in whom ureteral pathology was ruled out, we found other alterations that explained the symptoms, (gallbladder stones, disk protrusion). The Pielo CT let decide a therapeutical approach in 20 or 21 patients with ureteral pathology. (author)

  17. Helical type vacuum container

    International Nuclear Information System (INIS)

    Owada, Kimio.

    1989-01-01

    Helical type vacuum containers in the prior art lack in considerations for thermal expansion stresses to helical coils, and there is a possibility of coil ruptures. The object of the present invention is to avoid the rupture of helical coils wound around the outer surface of a vacuum container against heat expansion if any. That is, bellows or heat expansion absorbing means are disposed to a cross section of a helical type vacuum container. With such a constitution, thermal expansion of helical coils per se due to temperature elevation of the coils during electric supply can be absorbed by expansion of the bellows or absorption of the heat expansion absorbing means. Further, this can be attained by arranging shear pins in the direction perpendicular to the bellows axis so that the bellows are not distorted when the helical coils are wound around the helical type vacuum container. (I.S.)

  18. Raman selection rule of surface optical phonon in ZnS nanobelts

    KAUST Repository

    Ho, Chih-Hsiang; Varadhan, Purushothaman; Wang, Hsin-Hua; Chen, Cheng-Ying; Fang, Xiaosheng; He, Jr-Hau

    2016-01-01

    We report Raman scattering results of high-quality wurtzite ZnS nanobelts (NBs) grown by chemical vapor deposition. In Raman spectrum, the ensembles of ZnS NBs exhibit first order phonon modes at 274 cm-1 and 350 cm-1, corresponding to A1/E1 transverse optical and A1/E1 longitudinal optical phonons, in addition with strong surface optical (SO) phonon mode at 329 cm-1. The existence of SO band is confirmed by its shift with different surrounding dielectric media. Polarization dependent Raman spectrum was performed on a single ZnS NB and for the first time SO phonon band has been detected on a single nanobelt. Different selection rules of SO phonon modeshown from their corresponding E1/A1 phonon modeswere attributed to the anisotropic translational symmetry breaking on the NB surface.

  19. Raman selection rule of surface optical phonon in ZnS nanobelts

    KAUST Repository

    Ho, Chih-Hsiang

    2016-02-18

    We report Raman scattering results of high-quality wurtzite ZnS nanobelts (NBs) grown by chemical vapor deposition. In Raman spectrum, the ensembles of ZnS NBs exhibit first order phonon modes at 274 cm-1 and 350 cm-1, corresponding to A1/E1 transverse optical and A1/E1 longitudinal optical phonons, in addition with strong surface optical (SO) phonon mode at 329 cm-1. The existence of SO band is confirmed by its shift with different surrounding dielectric media. Polarization dependent Raman spectrum was performed on a single ZnS NB and for the first time SO phonon band has been detected on a single nanobelt. Different selection rules of SO phonon modeshown from their corresponding E1/A1 phonon modeswere attributed to the anisotropic translational symmetry breaking on the NB surface.

  20. Selection rules for Cooper pairing in two-dimensional interfaces and sheets

    Science.gov (United States)

    Scheurer, Mathias S.; Agterberg, Daniel F.; Schmalian, Jörg

    2017-12-01

    Thin sheets deposited on a substrate and interfaces of correlated materials offer a plethora of routes towards the realization of exotic phases of matter. In these systems, inversion symmetry is broken which strongly affects the properties of possible instabilities—in particular in the superconducting channel. By combining symmetry and energetic arguments, we derive general and experimentally accessible selection rules for Cooper instabilities in noncentrosymmetric systems, which yield necessary and sufficient conditions for spontaneous time-reversal-symmetry breaking at the superconducting transition and constrain the orientation of the triplet vector. We discuss in detail the implications for various different materials. For instance, we conclude that the pairing state in thin layers of Sr2RuO4 must, as opposed to its bulk superconducting state, preserve time-reversal symmetry with its triplet vector being parallel to the plane of the system. All triplet states of this system allowed by the selection rules are predicted to display topological Majorana modes at dislocations or at the edge of the system. Applying our results to the LaAlO3/SrTiO3 heterostructures, we find that while the condensates of the (001) and (110) oriented interfaces must be time-reversal symmetric, spontaneous time-reversal-symmetry breaking can only occur for the less studied (111) interface. We also discuss the consequences for thin layers of URu2Si2 and UPt3 as well as for single-layer FeSe. On a more general level, our considerations might serve as a design principle in the search for time-reversal-symmetry-breaking superconductivity in the absence of external magnetic fields.

  1. Communication: The H{sub 2}@C{sub 60} inelastic neutron scattering selection rule: Expanded and explained

    Energy Technology Data Exchange (ETDEWEB)

    Poirier, Bill, E-mail: Bill.Poirier@ttu.edu [Department of Chemistry and Biochemistry, and Department of Physics, Texas Tech University, Box 41061, Lubbock, Texas 79409-1061 (United States)

    2015-09-14

    Recently [M. Xu et al., J. Chem. Phys. 139, 064309 (2013)], an unexpected selection rule was discovered for the title system, contradicting the previously held belief that inelastic neutron scattering (INS) is not subject to any selection rules. Moreover, the newly predicted forbidden transitions, which emerge only in the context of coupled H{sub 2} translation-rotation (TR) dynamics, have been confirmed experimentally. However, a simple physical understanding, e.g., based on group theory, has been heretofore lacking. This is provided in the present paper, in which we (1) derive the correct symmetry group for the H{sub 2}@C{sub 60} TR Hamiltonian and eigenstates; (2) complete the INS selection rule, and show that the set of forbidden transitions is actually much larger than previously believed; and (3) evaluate previous theoretical and experimental results, in light of the new findings.

  2. Path selection rules for droplet trains in single-lane microfluidic networks

    Science.gov (United States)

    Amon, A.; Schmit, A.; Salkin, L.; Courbin, L.; Panizza, P.

    2013-07-01

    We investigate the transport of periodic trains of droplets through microfluidic networks having one inlet, one outlet, and nodes consisting of T junctions. Variations of the dilution of the trains, i.e., the distance between drops, reveal the existence of various hydrodynamic regimes characterized by the number of preferential paths taken by the drops. As the dilution increases, this number continuously decreases until only one path remains explored. Building on a continuous approach used to treat droplet traffic through a single asymmetric loop, we determine selection rules for the paths taken by the drops and we predict the variations of the fraction of droplets taking these paths with the parameters at play including the dilution. Our results show that as dilution decreases, the paths are selected according to the ascending order of their hydrodynamic resistance in the absence of droplets. The dynamics of these systems controlled by time-delayed feedback is complex: We observe a succession of periodic regimes separated by a wealth of bifurcations as the dilution is varied. In contrast to droplet traffic in single asymmetric loops, the dynamical behavior in networks of loops is sensitive to initial conditions because of extra degrees of freedom.

  3. Dosimetric selection for helical tomotherapy based stereotactic ablative radiotherapy for early-stage non-small cell lung cancer or lung metastases.

    Directory of Open Access Journals (Sweden)

    Alexander Chi

    Full Text Available BACKGROUND: No selection criteria for helical tomotherapy (HT based stereotactic ablative radiotherapy (SABR to treat early stage non-small cell lung cancer (NSCLC or solitary lung metastases has been established. In this study, we investigate the dosimetric selection criteria for HT based SABR delivering 70 Gy in 10 fractions to avoid severe toxicity in the treatment of centrally located lesions when adequate target dose coverage is desired. MATERIALS AND METHODS: 78 HT-SABR plans for solitary lung lesions were created to prescribe 70 Gy in 10 fractions to the planning target volume (PTV. The PTV was set to have ≥95% PTV receiving 70 Gy in each case. The cases for which dose constraints for ≥1 OAR could not be met without compromising the target dose coverage were compared with cases for which all target and OAR dose constraints were met. RESULTS: There were 23 central lesions for which OAR dose constraints could not be met without compromising PTV dose coverage. Comparing to cases for which optimal HT-based SABR plans were generated, they were associated with larger tumor size (5.72±1.96 cm vs. 3.74±1.49 cm, p<0.0001, higher lung dose, increased number of immediately adjacent OARs ( 3.45±1.34 vs. 1.66±0.81, p<0.0001, and shorter distance to the closest OARs (GTV: 0.26±0.22 cm vs. 0.88±0.54 cm, p<0.0001; PTV 0.19±0.18 cm vs. 0.48±0.36 cm, p = 0.0001. CONCLUSION: Delivery of 70 Gy in 10 fractions with HT to meet all the given OAR and PTV dose constraints are most likely when the following parameters are met: lung lesions ≤3.78 cm (11.98 cc, ≤2 immediately adjacent OARs which are ≥0.45 cm from the gross lesion and ≥0.21 cm from the PTV.

  4. Selection rules for single-chain-magnet behaviour in non-collinear Ising systems

    Energy Technology Data Exchange (ETDEWEB)

    Vindigni, Alessandro [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zuerich (Switzerland); Pini, Maria Gloria [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, I-50019 Sesto Fiorentino (Italy)], E-mail: vindigni@phys.ethz.ch

    2009-06-10

    The magnetic behaviour of molecular single-chain magnets is investigated in the framework of a one-dimensional Ising model with single spin-flip Glauber dynamics. Opportune modifications to the original theory are required in order to account for non-collinearity of local anisotropy axes between themselves and with respect to the crystallographic (laboratory) frame. The extension of Glauber's theory to the case of a collinear Ising ferrimagnetic chain is also discussed. Within this formalism, both the dynamics of magnetization reversal in zero field and the response of the system to a weak magnetic field, oscillating in time, are studied. Depending on the experimental geometry, selection rules are found for the occurrence of slow relaxation of the magnetization at low temperatures, as well as for resonant behaviour of the a.c. susceptibility as a function of temperature at low frequencies. The present theory applies successfully to some real systems, namely Mn-, Dy- and Co-based molecular magnetic chains, showing that single-chain-magnet behaviour is not only a feature of collinear ferro- and ferrimagnetic, but also of canted antiferromagnetic chains.

  5. A PROBABILITY BASED APPROACH FOR THE ALLOCATION OF PLAYER DRAFT SELECTIONS IN AUSTRALIAN RULES FOOTBALL

    Directory of Open Access Journals (Sweden)

    Anthony Bedford

    2006-12-01

    Full Text Available Australian Rules Football, governed by the Australian Football League (AFL is the most popular winter sport played in Australia. Like North American team based leagues such as the NFL, NBA and NHL, the AFL uses a draft system for rookie players to join a team's list. The existing method of allocating draft selections in the AFL is simply based on the reverse order of each team's finishing position for that season, with teams winning less than or equal to 5 regular season matches obtaining an additional early round priority draft pick. Much criticism has been levelled at the existing system since it rewards losing teams and does not encourage poorly performing teams to win matches once their season is effectively over. We propose a probability-based system that allocates a score based on teams that win 'unimportant' matches (akin to Carl Morris' definition of importance. We base the calculation of 'unimportance' on the likelihood of a team making the final eight following each round of the season. We then investigate a variety of approaches based on the 'unimportance' measure to derive a score for 'unimportant' and unlikely wins. We explore derivatives of this system, compare past draft picks with those obtained under our system, and discuss the attractiveness of teams knowing the draft reward for winning each match in a season

  6. Selection rules for single-chain-magnet behaviour in non-collinear Ising systems

    International Nuclear Information System (INIS)

    Vindigni, Alessandro; Pini, Maria Gloria

    2009-01-01

    The magnetic behaviour of molecular single-chain magnets is investigated in the framework of a one-dimensional Ising model with single spin-flip Glauber dynamics. Opportune modifications to the original theory are required in order to account for non-collinearity of local anisotropy axes between themselves and with respect to the crystallographic (laboratory) frame. The extension of Glauber's theory to the case of a collinear Ising ferrimagnetic chain is also discussed. Within this formalism, both the dynamics of magnetization reversal in zero field and the response of the system to a weak magnetic field, oscillating in time, are studied. Depending on the experimental geometry, selection rules are found for the occurrence of slow relaxation of the magnetization at low temperatures, as well as for resonant behaviour of the a.c. susceptibility as a function of temperature at low frequencies. The present theory applies successfully to some real systems, namely Mn-, Dy- and Co-based molecular magnetic chains, showing that single-chain-magnet behaviour is not only a feature of collinear ferro- and ferrimagnetic, but also of canted antiferromagnetic chains.

  7. Organisational justice rules as determinants of black and white employees' fairness perceptions of personnel selection techniques

    Directory of Open Access Journals (Sweden)

    Angela de Jong

    2000-06-01

    Full Text Available The diversity of the South African population may lead to opinions that test fairness is not a pure empirical problem, but requires certain subjective value judgements. The aim of this study was to identify applicants' underlying reasons for evaluating a selection technique as being fair/unfair. These fairness perceptions were analysed by means of the organisational justice theory. The total sample consisted of 328 mature university students (M = 30,6 all of whom had work experience. The analyses comprised two sets of comparisons. The first set involved Black (uninformed and White (uninformed groups. The second comparison involved informed versus uninformed black students. Exposure to the subjects Strategic Personnel Management and/or undergraduate Industrial Psycohology, in which the nature and value of various selection techniques are studied, constituted the variable'being informed'. It was hypothesised that the Black (uninformed and the White (uninformed groups would perceive the value of the 11 justice rules for the total fairness perception across the ten selection techniques differently. Substantial support was found for this hypothesis. The same hypothesis was investigated for the Black (informed and the Black (uninformed groups, but no significant differences were found to support the latter hypothesis. The implications of these findings are discussed in terms of South African selection practices. Opsomming Die diversiteit van die Suid-Afrikaanse bevolking mag daartoe lei dat persepsies van die billikheid van verskillende personeelkeuringtegnieke op n verskeidenheid van subjektiewe waarde-oordele gegrond word. Dit is die doel van hierdie ondersoek om die onderliggende redes waarvolgens kandidate keuringtegnieke as billik/onbillik evalueer, te identifiseer. Die kandidate se billikheidpersepsies van tien keuringtegnieke is aan die hand van die organisatoriese billikheidteorie ontleed. Die steekproef het bestaan uit 328 volwasse

  8. Confirming a predicted selection rule in inelastic neutron scattering spectroscopy: the quantum translator-rotator H2 entrapped inside C60.

    Science.gov (United States)

    Xu, Minzhong; Jiménez-Ruiz, Mónica; Johnson, Mark R; Rols, Stéphane; Ye, Shufeng; Carravetta, Marina; Denning, Mark S; Lei, Xuegong; Bačić, Zlatko; Horsewill, Anthony J

    2014-09-19

    We report an inelastic neutron scattering (INS) study of a H2 molecule encapsulated inside the fullerene C60 which confirms the recently predicted selection rule, the first to be established for the INS spectroscopy of aperiodic, discrete molecular compounds. Several transitions from the ground state of para-H2 to certain excited translation-rotation states, forbidden according to the selection rule, are systematically absent from the INS spectra, thus validating the selection rule with a high degree of confidence. Its confirmation sets a precedent, as it runs counter to the widely held view that the INS spectroscopy of molecular compounds is not subject to any selection rules.

  9. Site selection under the underground geologic store plan. Procedures of selecting underground geologic stores as disputed by society, science, and politics. Site selection rules

    International Nuclear Information System (INIS)

    Aebersold, M.

    2008-01-01

    The new Nuclear Power Act and the Nuclear Power Ordinance of 2005 are used in Switzerland to select a site of an underground geologic store for radioactive waste in a substantive planning procedure. The ''Underground Geologic Store Substantive Plan'' is to ensure the possibility to build underground geologic stores in an independent, transparent and fair procedure. The Federal Office for Energy (BFE) is the agency responsible for this procedure. The ''Underground Geologic Store'' Substantive Plan comprises these principles: - The long term protection of people and the environment enjoys priority. Aspects of regional planning, economics and society are of secondary importance. - Site selection is based on the waste volumes arising from the five nuclear power plants currently existing in Switzerland. The Substantive Plan is no precedent for or against future nuclear power plants. - A transparent and fair procedure is an indispensable prerequisite for achieving the objectives of a Substantive Plan, i.e., finding accepted sites for underground geologic stores. The Underground Geologic Stores Substantive Plan is arranged in two parts, a conceptual part defining the rules of the selection process, and an implementation part documenting the selection process step by step and, in the end, naming specific sites of underground geologic stores in Switzerland. The objective is to be able to commission underground geologic stores in 25 or 35 years' time. In principle, 2 sites are envisaged, one for low and intermediate level waste, and one for high level waste. The Swiss Federal Council approved the conceptual part on April 2, 2008. This marks the beginning of the implementation phase and the site selection process proper. (orig.)

  10. The Bethe Sum Rule and Basis Set Selection in the Calculation of Generalized Oscillator Strengths

    DEFF Research Database (Denmark)

    Cabrera-Trujillo, Remigio; Sabin, John R.; Oddershede, Jens

    1999-01-01

    Fulfillment of the Bethe sum rule may be construed as a measure of basis set quality for atomic and molecular properties involving the generalized oscillator strength distribution. It is first shown that, in the case of a complete basis, the Bethe sum rule is fulfilled exactly in the random phase...

  11. Group IV all-semiconductor spintronics. Materials aspects and optical spin selection rules

    Energy Technology Data Exchange (ETDEWEB)

    Sircar, Narayan

    2012-04-03

    particular, by including recent theory on spin-dependent selection rules for radiative transitions in bulk Si, we adapt an expression for the magnetic-field-induced photoluminescence polarization of direct band gap semiconductor materials of GaAs-type to Si. Measurements within an applied magnetic field of the degree of circular polarization of phononassisted photoluminescence of bulk Si for different doping are presented. Similar experiments on the photoluminescence of Ge quantum dot ensembles evidence a peculiarity for the spin-dependent selection rules for phononless radiative recombinations. We propose a connection between this finding and the confined character of electrons that are involved in the transitions. Furthermore, we try to optically inject and detect confined carrier spins in Ge quantum dot ensembles. For nonresonant excitation these efforts are unsuccessful, which we attribute to a hole spin relaxation that happens faster than the combined capture of the hole by the quantum dot and the radiative decay of the hole. Finally, we employ the p-type GeMn thin film layers presented in the first part of this work as spin-polarizing contacts for Si/SiGe-based light-emitting diodes with the aim to inject spin-polarized holes. Preliminary results of a circularly polarized electroluminescence of these devices propose the possibility of a successful hole spin injection near liquid helium temperatures.

  12. Helical Antimicrobial Sulfono- {gamma} -AApeptides

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yaqiong; Wu, Haifan; Teng, Peng; Bai, Ge; Lin, Xiaoyang; Zuo, Xiaobing; Cao, Chuanhai; Cai, Jianfeng

    2015-06-11

    Host-defense peptides (HDPs) such as magainin 2 have emerged as potential therapeutic agents combating antibiotic resistance. Inspired by their structures and mechanism of action, herein we report the fi rst example of antimicrobial helical sulfono- γ - AApeptide foldamers. The lead molecule displays broad-spectrum and potent antimicrobial activity against multi-drug-resistant Gram- positive and Gram-negative bacterial pathogens. Time-kill studies and fl uorescence microscopy suggest that sulfono- γ -AApeptides eradicate bacteria by taking a mode of action analogous to that of HDPs. Clear structure - function relationships exist in the studied sequences. Longer sequences, presumably adopting more-de fi ned helical structures, are more potent than shorter ones. Interestingly, the sequence with less helical propensity in solution could be more selective than the stronger helix-forming sequences. Moreover, this class of antimicrobial agents are resistant to proteolytic degradation. These results may lead to the development of a new class of antimicrobial foldamers combating emerging antibiotic-resistant pathogens.

  13. A note on helicity

    International Nuclear Information System (INIS)

    Bialynicki-Birula, I.; Newmann, E.T.; Porter, J.; Winicour, J.; Lukacs, B.; Perjes, Z.; Sebestyen, A.

    1981-03-01

    The authors give a formal definition of the helicity operator for integral spin fields, which does not involve their momentum-space decomposition. The discussion is based upon a representation of the Pauli-Lubanski operator in terms of the action on tensor fields by the Killing vectors associated with the generators of the Poincare group. This leads to an identification of the helicity operator with the duality operator defined by the space-time alternating tensor. Helicity eigenstates then correspond to self-dual or anti-self-dual fields, in agreement with usage implicit in the literature. In addiition, the relationship between helicity eigenstates which are intrinsically non-classical, and states of right or left circular polarization in classical electrodynamics are discussed. (author)

  14. Predicting higher selection in elite junior Australian Rules football: The influence of physical performance and anthropometric attributes.

    Science.gov (United States)

    Robertson, Sam; Woods, Carl; Gastin, Paul

    2015-09-01

    To develop a physiological performance and anthropometric attribute model to predict Australian Football League draft selection. Cross-sectional observational. Data was obtained (n=4902) from three Under-18 Australian football competitions between 2010 and 2013. Players were allocated into one of the three groups, based on their highest level of selection in their final year of junior football (Australian Football League Drafted, n=292; National Championship, n=293; State-level club, n=4317). Physiological performance (vertical jumps, agility, speed and running endurance) and anthropometric (body mass and height) data were obtained. Hedge's effect sizes were calculated to assess the influence of selection-level and competition on these physical attributes, with logistic regression models constructed to discriminate Australian Football League Drafted and National Championship players. Rule induction analysis was undertaken to determine a set of rules for discriminating selection-level. Effect size comparisons revealed a range of small to moderate differences between State-level club players and both other groups for all attributes, with trivial to small differences between Australian Football League Drafted and National Championship players noted. Logistic regression models showed multistage fitness test, height and 20 m sprint time as the most important attributes in predicting Draft success. Rule induction analysis showed that players displaying multistage fitness test scores of >14.01 and/or 20 m sprint times of football players being recruited to the highest level of the sport. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  15. Helical CT defecography

    International Nuclear Information System (INIS)

    Ferrando, R.; Fiorini, G.; Beghello, A.; Cicio, G.R.; Derchi, L.E.; Consigliere, M.; Resasco, M.; Tornago, S.

    1999-01-01

    The purpose of this work is to investigate the possible role of Helical CT defecography in pelvic floor disorders by comparing the results of the investigations with those of conventional defecography. The series analyzed consisted of 90 patients, namely 62 women and 28 men, ranging in age 24-82 years. They were all submitted to conventional defecography, and 18 questionable cases were also studied with Helical CT defecography. The conventional examination was performed during the 4 standard phases of resting, squeezing, Valsalva and straining; it is used a remote-control unit. The parameters for Helical CT defecography were: 5 mm beam collimation, pitch 2, 120 KV, 250 m As and 18-20 degrees gantry inclination to acquire coronal images of the pelvic floor. The rectal ampulla was distended with a bolus of 300 mL nonionic iodinated contrast agent (dilution: 3g/cc). The patient wore a napkin and was seated on the table, except for those who could not hold the position and were thus examined supine. Twenty-second helical scans were performed at rest and during evacuation; multiplanar reconstructions were obtained especially on the sagittal plane for comparison with conventional defecographic images. Coronal Helical CT defecography images permitted to map the perineal floor muscles, while sagittal reconstructions provided information on the ampulla and the levator ani. To conclude, Helical CT defecography performed well in study of pelvic floor disorders and can follow conventional defecography especially in questionable cases [it

  16. CURRENT AND KINETIC HELICITY OF LONG-LIVED ACTIVITY COMPLEXES

    International Nuclear Information System (INIS)

    Komm, Rudolf; Gosain, Sanjay

    2015-01-01

    We study long-lived activity complexes and their current helicity at the solar surface and their kinetic helicity below the surface. The current helicity has been determined from synoptic vector magnetograms from the NSO/SOLIS facility, and the kinetic helicity of subsurface flows has been determined with ring-diagram analysis applied to full-disk Dopplergrams from NSO/GONG and SDO/HMI. Current and kinetic helicity of activity complexes follow the hemispheric helicity rule with mainly positive values (78%; 78%, respectively, with a 95% confidence level of 31%) in the southern hemisphere and negative ones (80%; 93%, respectively, with a 95% confidence level of 22% and 14%, respectively) in the northern hemisphere. The locations with the dominant sign of kinetic helicity derived from Global Oscillation Network Group (GONG) and SDO/HMI data are more organized than those of the secondary sign even if they are not part of an activity complex, while locations with the secondary sign are more fragmented. This is the case for both hemispheres even for the northern one where it is not as obvious visually due to the large amount of magnetic activity present as compared to the southern hemisphere. The current helicity shows a similar behavior. The dominant sign of current helicity is the same as that of kinetic helicity for the majority of the activity complexes (83% with a 95% confidence level of 15%). During the 24 Carrington rotations analyzed here, there is at least one longitude in each hemisphere where activity complexes occur repeatedly throughout the epoch. These ''active'' longitudes are identifiable as locations of strong current and kinetic helicity of the same sign

  17. Political expediency and the rule of law in Africa: A focus on selected ...

    African Journals Online (AJOL)

    Beginning in the late 1980s and due to a confl uence of domestic and international forces, Africa's political realities began changing, resulting in good governance, including the rule of law taking centre stage in both the discourse and practice of post-Cold War African politics. However, in some cases the continent's ...

  18. Helicity, Reconnection, and Dynamo Effects

    International Nuclear Information System (INIS)

    Ji, Hantao

    1998-01-01

    The inter-relationships between magnetic helicity, magnetic reconnection, and dynamo effects are discussed. In laboratory experiments, where two plasmas are driven to merge, the helicity content of each plasma strongly affects the reconnection rate, as well as the shape of the diffusion region. Conversely, magnetic reconnection events also strongly affect the global helicity, resulting in efficient helicity cancellation (but not dissipation) during counter-helicity reconnection and a finite helicity increase or decrease (but less efficiently than dissipation of magnetic energy) during co-helicity reconnection. Close relationships also exist between magnetic helicity and dynamo effects. The turbulent electromotive force along the mean magnetic field (alpha-effect), due to either electrostatic turbulence or the electron diamagnetic effect, transports mean-field helicity across space without dissipation. This has been supported by direct measurements of helicity flux in a laboratory plasma. When the dynamo effect is driven by electromagnetic turbulence, helicity in the turbulent field is converted to mean-field helicity. In all cases, however, dynamo processes conserve total helicity except for a small battery effect, consistent with the observation that the helicity is approximately conserved during magnetic relaxation

  19. Helicity-dependent reaction γd → π0d near the η-threshold and its contribution to the E-asymmetry and the GDH sum rule for the deuteron

    International Nuclear Information System (INIS)

    Darwish, Eed M.; Hemmdan, A.; El-Shamy, N.T.

    2015-01-01

    The helicity-dependent coherent π 0 -photoproduction in the reaction γd → π 0 d near the η-threshold is investigated. The calculations are performed within an approach which includes the reaction amplitudes of the impulse approximation (IA), two-step process with intermediate πN- and ηN-rescattering, and the higher order terms in the multiple scattering series for the intermediate ηNN interaction. The contribution of γd → π 0 d to the deuteron spin asymmetry is calculated and its contribution to the Gerasimov–Drell–Hearn (GDH) integral is explicitly evaluated by integration up to a photon energy of 900 MeV. In addition, the helicity E-asymmetry is calculated. The results revealed that the doubly polarized differential cross-sections and the helicity E-asymmetry are sensitive to the interference of rescattering effects, specially at photon energies 600–800 MeV and extreme backward pion angles. The sensitivity of the obtained results for the GDH integral to the choice of NN potential model governing the deuteron wave function is discussed. We find that the deviation among results obtained for the deuteron GDH integral using different deuteron wave functions is quite large. (author)

  20. A PMBGA to Optimize the Selection of Rules for Job Shop Scheduling Based on the Giffler-Thompson Algorithm

    Directory of Open Access Journals (Sweden)

    Rui Zhang

    2012-01-01

    Full Text Available Most existing research on the job shop scheduling problem has been focused on the minimization of makespan (i.e., the completion time of the last job. However, in the fiercely competitive market nowadays, delivery punctuality is more important for maintaining a high service reputation. So in this paper, we aim at solving job shop scheduling problems with the total weighted tardiness objective. Several dispatching rules are adopted in the Giffler-Thompson algorithm for constructing active schedules. It is noticeable that the rule selections for scheduling consecutive operations are not mutually independent but actually interrelated. Under such circumstances, a probabilistic model-building genetic algorithm (PMBGA is proposed to optimize the sequence of selected rules. First, we use Bayesian networks to model the distribution characteristics of high-quality solutions in the population. Then, the new generation of individuals is produced by sampling the established Bayesian network. Finally, some elitist individuals are further improved by a special local search module based on parameter perturbation. The superiority of the proposed approach is verified by extensive computational experiments and comparisons.

  1. Combining Fuzzy AHP with GIS and Decision Rules for Industrial Site Selection

    Directory of Open Access Journals (Sweden)

    Aissa Taibi

    2017-12-01

    Full Text Available This study combines Fuzzy Analytic Hierarchy Process (FAHP, Geographic Information System (GIS and Decision rules to provide decision makers with a ranking model for industrial sites in Algeria. A ranking of the suitable industrial areas is a crucial multi-criteria decision problem based on socio-economical and technical criteria as on environmental considerations. Fuzzy AHP is used for assessment of the candidate industrial sites by combining fuzzy set theory and analytic hierarchy process (AHP. The decision rule base serves as a filter that performs criteria pre-treatment involving a reduction of their numbers. GIS is used to overlay, generate criteria maps and for visualizing ranked zones on the map. The rank of a zone so obtained is an index that guides decision-makers to the best utilization of the zone in future.

  2. Measuring Nominal and Real Convergence of Selected CEE Countries by the Taylor Rule

    Directory of Open Access Journals (Sweden)

    Böing Tobias

    2016-12-01

    Full Text Available We propose using a simple Taylor rule to evaluate business cycle convergence of the Czech Republic, Hungary, and Poland with the Eurozone. Our findings indicate an ongoing convergence of those CEE countries to the Eurozone, but with instabilities and heterogeneity between the countries. Especially Poland has shown a high degree of convergence in recent years. But there are still relevant differences in Taylor rates of each country to the Eurozone of about two percentage points.

  3. Multi-scale inference of interaction rules in animal groups using Bayesian model selection.

    Directory of Open Access Journals (Sweden)

    Richard P Mann

    2012-01-01

    Full Text Available Inference of interaction rules of animals moving in groups usually relies on an analysis of large scale system behaviour. Models are tuned through repeated simulation until they match the observed behaviour. More recent work has used the fine scale motions of animals to validate and fit the rules of interaction of animals in groups. Here, we use a Bayesian methodology to compare a variety of models to the collective motion of glass prawns (Paratya australiensis. We show that these exhibit a stereotypical 'phase transition', whereby an increase in density leads to the onset of collective motion in one direction. We fit models to this data, which range from: a mean-field model where all prawns interact globally; to a spatial Markovian model where prawns are self-propelled particles influenced only by the current positions and directions of their neighbours; up to non-Markovian models where prawns have 'memory' of previous interactions, integrating their experiences over time when deciding to change behaviour. We show that the mean-field model fits the large scale behaviour of the system, but does not capture fine scale rules of interaction, which are primarily mediated by physical contact. Conversely, the Markovian self-propelled particle model captures the fine scale rules of interaction but fails to reproduce global dynamics. The most sophisticated model, the non-Markovian model, provides a good match to the data at both the fine scale and in terms of reproducing global dynamics. We conclude that prawns' movements are influenced by not just the current direction of nearby conspecifics, but also those encountered in the recent past. Given the simplicity of prawns as a study system our research suggests that self-propelled particle models of collective motion should, if they are to be realistic at multiple biological scales, include memory of previous interactions and other non-Markovian effects.

  4. Helical-D pinch

    International Nuclear Information System (INIS)

    Schaffer, M.J.

    1997-08-01

    A stabilized pinch configuration is described, consisting of a D-shaped plasma cross section wrapped tightly around a guiding axis. The open-quotes helical-Dclose quotes geometry produces a very large axial (toroidal) transform of magnetic line direction that reverses the pitch of the magnetic lines without the need of azimuthal (poloidal) plasma current. Thus, there is no need of a open-quotes dynamoclose quotes process and its associated fluctuations. The resulting configuration has the high magnetic shear and pitch reversal of the reversed field pinch (RFP). (Pitch = P = qR, where R = major radius). A helical-D pinch might demonstrate good confinement at q << 1

  5. Dynamic helical CT mammography of breast cancer

    International Nuclear Information System (INIS)

    Yamamoto, Akira; Fukushima, Hitoshi; Okamura, Ryuji; Nakamura, Yoshiaki; Morimoto, Taisuke; Urata, Yoji; Mukaihara, Sumio; Hayakawa, Katsumi

    2006-01-01

    The purpose of this study was to determine whether dynamic helical computed tomography (CT)-mammography could assist in selecting the most appropriate surgical method in women with breast cancer. Preoperative contrast-enhanced helical CT scanning of the breast was performed on 133 female patients with suspicion of breast cancer at the same time as clinical, mammographic, and/or ultrasonographic examinations. The patients were scanned in the prone position with a specially designed CT-compatible device. A helical scan was made with rapid intravenous bolus injection (3 ml/s) of 100 ml of iodine contrast material. Three-dimensional maximum intensity projection (MIP) images were reconstructed, and CT findings were correlated with surgical and histopathological findings. Histopathological analysis revealed 84 malignant lesions and seven benign lesions. The sensitivity, specificity, and accuracy levels of the CT scanning were 94.6%, 58.6%, and 78.9%. Helical scanning alone revealed additional contralateral carcinomas in three of four patients and additional ipsilateral carcinomas in three of five patients. However, the technique gave false-positive readings in 24 patients. The preoperative CT-mammogram altered the surgical method in six patients. Dynamic helical CT-mammography in the prone position may be one of the choices of adjunct imaging in patients with suspected breast cancer scheduled for surgery. (author)

  6. Review of the helicity formalism

    International Nuclear Information System (INIS)

    Barreiro, F.; Cerrada, M.; Fernandez, E.

    1972-01-01

    Our purpose in these notes has been to present a brief and general review of the helicity formalism. We begin by discussing Lorentz invariance, spin and helicity ideas, in section 1 . In section 2 we deal with the construction of relativistic states and scattering amplitudes in the helicity basis and we study their transformation properties under discrete symmetries. Finally we present some more sophisticated topics like kinematical singularities of helicity amplitudes, kinematical constraints and crossing relations 3, 4, 5 respectively. (Author) 8 refs

  7. Helical Confinement Concepts

    Energy Technology Data Exchange (ETDEWEB)

    Beidler, C; Brakel, R; Burhenn, R; Dinklage, A; Erckmann, V; Feng, Y; Geiger, J; Hartmann, D; Hirsch, M; Jaenicke, R; Koenig, R; Laqua, H P; Maassberg, H; Wagner, F; Weller, A; Wobig, H [Max-Planck Institut fuer Plasmaphysik, EURATOM Association, Greifswald (Germany)

    2012-09-15

    Stellarators, conceived 1951 by Lyman Spitzer in Princeton, are toroidal devices that confine a plasma in a magnetic field which originates from currents in coils outside the plasma. A plasma current driven by external means, for example by an ohmic transformer, is not required for confinement. Supplying the desired poloidal field component by external coils leads to a helically structured plasma topology. Thus stellarators - or helical confinement devices - are fully three-dimensional in contrast to the toroidal (rotational) symmetry of tokamaks. As stellarators can be free of an inductive current, whose radial distribution depends on the plasma parameters, their equilibrium must not be established via the evolving plasma itself, but to a first order already given by the vacuum magnetic field. They do not need an active control (like positional feedback) and therefore cannot suffer from its failure. The outstanding conceptual advantage of stellarators is the potential of steady state plasma operation without current drive. As there is no need for current drive, the recirculating power is expected to be smaller than in equivalent tokamaks. The lack of a net current avoids current driven instabilities; specifically, no disruptions, no resistive wall modes and no conventional or neoclassical tearing modes appear. Second order pressure-driven currents (Pfirsch-Schlueter, bootstrap) exist but they can be modified and even minimized by the magnetic design. The magnetic configuration of helical devices naturally possesses a separatrix, which allows the implementation of a helically structured divertor for exhaust and impurity control. (author)

  8. Rules for selection of computer system to support customer relationships management

    Directory of Open Access Journals (Sweden)

    Dorota Buchnowska

    2012-12-01

    Full Text Available The number of support systems for business management on the Polish market is increasing. Because of that, enterprises are facing a more and more difficult dilemma: which solution to choose? This paper will present stages of the selection process of applications for customer relationships management support, discuss selection criteria and present a decision making tool for the selection of management support system, allowing for multi-faceted and impartial comparison of business applications.

  9. Manifestation of spin selection rules on the quantum tunneling of magnetization in a single-molecule magnet.

    Science.gov (United States)

    Henderson, J J; Koo, C; Feng, P L; del Barco, E; Hill, S; Tupitsyn, I S; Stamp, P C E; Hendrickson, D N

    2009-07-03

    We present low temperature magnetometry measurements on a new Mn3 single-molecule magnet in which the quantum tunneling of magnetization (QTM) displays clear evidence for quantum mechanical selection rules. A QTM resonance appearing only at high temperatures demonstrates tunneling between excited states with spin projections differing by a multiple of three. This is dictated by the C3 molecular symmetry, which forbids pure tunneling from the lowest metastable state. Transverse field resonances are understood by correctly orienting the Jahn-Teller axes of the individual manganese ions and including transverse dipolar fields. These factors are likely to be important for QTM in all single-molecule magnets.

  10. Selecting Tanker Steaming Speeds under Uncertainty: A Rule-Based Bayesian Reasoning Approach

    Directory of Open Access Journals (Sweden)

    N.S.F. Abdul Rahman

    2015-06-01

    Full Text Available In the tanker industry, there are a lot of uncertain conditions that tanker companies have to deal with. For example, the global financial crisis and economic recession, the increase of bunker fuel prices and global climate change. Such conditions have forced tanker companies to change tankers speed from full speed to slow speed, extra slow speed and super slow speed. Due to such conditions, the objective of this paper is to present a methodology for determining vessel speeds of tankers that minimize the cost of the vessels under such conditions. The four levels of vessel speed in the tanker industry will be investigated and will incorporate a number of uncertain conditions. This will be done by developing a scientific model using a rule-based Bayesian reasoning method. The proposed model has produced 96 rules that can be used as guidance in the decision making process. Such results help tanker companies to determine the appropriate vessel speed to be used in a dynamic operational environmental.

  11. Multi-scale inference of interaction rules in animal groups using Bayesian model selection.

    Directory of Open Access Journals (Sweden)

    Richard P Mann

    Full Text Available Inference of interaction rules of animals moving in groups usually relies on an analysis of large scale system behaviour. Models are tuned through repeated simulation until they match the observed behaviour. More recent work has used the fine scale motions of animals to validate and fit the rules of interaction of animals in groups. Here, we use a Bayesian methodology to compare a variety of models to the collective motion of glass prawns (Paratya australiensis. We show that these exhibit a stereotypical 'phase transition', whereby an increase in density leads to the onset of collective motion in one direction. We fit models to this data, which range from: a mean-field model where all prawns interact globally; to a spatial Markovian model where prawns are self-propelled particles influenced only by the current positions and directions of their neighbours; up to non-Markovian models where prawns have 'memory' of previous interactions, integrating their experiences over time when deciding to change behaviour. We show that the mean-field model fits the large scale behaviour of the system, but does not capture the observed locality of interactions. Traditional self-propelled particle models fail to capture the fine scale dynamics of the system. The most sophisticated model, the non-Markovian model, provides a good match to the data at both the fine scale and in terms of reproducing global dynamics, while maintaining a biologically plausible perceptual range. We conclude that prawns' movements are influenced by not just the current direction of nearby conspecifics, but also those encountered in the recent past. Given the simplicity of prawns as a study system our research suggests that self-propelled particle models of collective motion should, if they are to be realistic at multiple biological scales, include memory of previous interactions and other non-Markovian effects.

  12. Band-to-band transitions, selection rules, effective mass, and excitonic contributions in monoclinic β -Ga2O3

    Science.gov (United States)

    Mock, Alyssa; Korlacki, Rafał; Briley, Chad; Darakchieva, Vanya; Monemar, Bo; Kumagai, Yoshinao; Goto, Ken; Higashiwaki, Masataka; Schubert, Mathias

    2017-12-01

    We employ an eigenpolarization model including the description of direction dependent excitonic effects for rendering critical point structures within the dielectric function tensor of monoclinic β -Ga2O3 yielding a comprehensive analysis of generalized ellipsometry data obtained from 0.75-9 eV. The eigenpolarization model permits complete description of the dielectric response. We obtain, for single-electron and excitonic band-to-band transitions, anisotropic critical point model parameters including their polarization vectors within the monoclinic lattice. We compare our experimental analysis with results from density functional theory calculations performed using the Gaussian-attenuation-Perdew-Burke-Ernzerhof hybrid density functional. We present and discuss the order of the fundamental direct band-to-band transitions and their polarization selection rules, the electron and hole effective mass parameters for the three lowest band-to-band transitions, and their excitonic contributions. We find that the effective masses for holes are highly anisotropic and correlate with the selection rules for the fundamental band-to-band transitions. The observed transitions are polarized close to the direction of the lowest hole effective mass for the valence band participating in the transition.

  13. Coulomb double helical structure

    Science.gov (United States)

    Kamimura, Tetsuo; Ishihara, Osamu

    2012-01-01

    Structures of Coulomb clusters formed by dust particles in a plasma are studied by numerical simulation. Our study reveals the presence of various types of self-organized structures of a cluster confined in a prolate spheroidal electrostatic potential. The stable configurations depend on a prolateness parameter for the confining potential as well as on the number of dust particles in a cluster. One-dimensional string, two-dimensional zigzag structure and three-dimensional double helical structure are found as a result of the transition controlled by the prolateness parameter. The formation of stable double helical structures resulted from the transition associated with the instability of angular perturbations on double strings. Analytical perturbation study supports the findings of numerical simulations.

  14. Computational design and elaboration of a de novo heterotetrameric alpha-helical protein that selectively binds an emissive abiological (porphinato)zinc chromophore.

    Science.gov (United States)

    Fry, H Christopher; Lehmann, Andreas; Saven, Jeffery G; DeGrado, William F; Therien, Michael J

    2010-03-24

    The first example of a computationally de novo designed protein that binds an emissive abiological chromophore is presented, in which a sophisticated level of cofactor discrimination is pre-engineered. This heterotetrameric, C(2)-symmetric bundle, A(His):B(Thr), uniquely binds (5,15-di[(4-carboxymethyleneoxy)phenyl]porphinato)zinc [(DPP)Zn] via histidine coordination and complementary noncovalent interactions. The A(2)B(2) heterotetrameric protein reflects ligand-directed elements of both positive and negative design, including hydrogen bonds to second-shell ligands. Experimental support for the appropriate formulation of [(DPP)Zn:A(His):B(Thr)](2) is provided by UV/visible and circular dichroism spectroscopies, size exclusion chromatography, and analytical ultracentrifugation. Time-resolved transient absorption and fluorescence spectroscopic data reveal classic excited-state singlet and triplet PZn photophysics for the A(His):B(Thr):(DPP)Zn protein (k(fluorescence) = 4 x 10(8) s(-1); tau(triplet) = 5 ms). The A(2)B(2) apoprotein has immeasurably low binding affinities for related [porphinato]metal chromophores that include a (DPP)Fe(III) cofactor and the zinc metal ion hemin derivative [(PPIX)Zn], underscoring the exquisite active-site binding discrimination realized in this computationally designed protein. Importantly, elements of design in the A(His):B(Thr) protein ensure that interactions within the tetra-alpha-helical bundle are such that only the heterotetramer is stable in solution; corresponding homomeric bundles present unfavorable ligand-binding environments and thus preclude protein structural rearrangements that could lead to binding of (porphinato)iron cofactors.

  15. Helically linked mirror arrangement

    International Nuclear Information System (INIS)

    Ranjan, P.

    1986-08-01

    A scheme is described for helical linking of mirror sections, which endeavors to combine the better features of toroidal and mirror devices by eliminating the longitudinal loss of mirror machines, having moderately high average β and steady state operation. This scheme is aimed at a device, with closed magnetic surfaces having rotational transform for equilibrium, one or more axisymmetric straight sections for reduced radial loss, a simple geometrical axis for the links and an overall positive magnetic well depth for stability. We start by describing several other attempts at linking of mirror sections, made both in the past and the present. Then a description of our helically linked mirror scheme is given. This example has three identical straight sections connected by three sections having helical geometric axes. A theoretical analysis of the magnetic field and single-particle orbits in them leads to the conclusion that most of the passing particles would be confined in the device and they would have orbits independent of pitch angle under certain conditions. Numerical results are presented, which agree well with the theoretical results as far as passing particle orbits are concerned

  16. Bright ideas. Some rules of thumb for interior lighting design and selection.

    Science.gov (United States)

    Hunter, Claudia M

    2002-07-01

    Interior lighting design and selection can be a demanding assignment for a health facilities manager or department head. It requires a balance between conflicting needs, such as providing good task lighting for a nursing station while also shielding luminaires that are visible from patients' rooms to avoid glare.

  17. Helically coiled tube heat exchanger

    International Nuclear Information System (INIS)

    Harris, A.M.

    1981-01-01

    In a heat exchanger such as a steam generator for a nuclear reactor, two or more bundles of helically coiled tubes are arranged in series with the tubes in each bundle integrally continuing through the tube bundles arranged in series therewith. Pitch values for the tubing in any pair of tube bundles, taken transverse to the path of the reactor coolant flow about the tubes, are selected as a ratio of two unequal integers to permit efficient operation of each tube bundle while maintaining the various tube bundles of the heat exchanger within a compact envelope. Preferably, the helix angle and tube pitch parallel to the path of coolant flow are constant for all tubes in a single bundle so that the tubes are of approximately the same length within each bundle

  18. Low-tube-voltage selection for triple-rule-out CTA: relation to patient size

    Energy Technology Data Exchange (ETDEWEB)

    Takx, Richard A.P. [University Medical Center Utrecht, Department of Radiology, Utrecht (Netherlands); Krissak, Radko [Medical Faculty Mannheim - Heidelberg University, Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim (Germany); Hufeland Klinikum GmbH, Department of Diagnostic and Interventional Radiology, Bad Langensalza (Germany); Fink, Christian [Medical Faculty Mannheim - Heidelberg University, Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim (Germany); General Hospital Celle, Department of Radiology, Celle (Germany); Bachmann, Valentin; Henzler, Thomas; Meyer, Mathias; Schoenberg, Stefan O. [Medical Faculty Mannheim - Heidelberg University, Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim (Germany); Nance, John W. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Apfaltrer, Paul [Medical Faculty Mannheim - Heidelberg University, Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim (Germany); Medical University of Vienna, Department of Biomedical Imaging and Image-guided Therapy, Vienna (Austria)

    2017-06-15

    To investigate the relationship between image quality and patient size at 100 kilovoltage (kV) compared to 120 kV ECG-gated Triple-Rule-Out CT angiography (TRO-CTA). We retrospectively included 73 patients (age 64 ± 14 years) who underwent retrospective ECG-gated chest CTA. 40 patients were scanned with 100 kV while 33 patients with 120 kV. Body mass index (BMI), patients' chest circumference (PC) and thoracic surface area (TSA) were recorded. Quantitative image quality was assessed as vascular attenuation in the ascending aorta (AA), pulmonary trunk (PA) and left coronary artery (LCA) and the signal-to-noise ratio (SNR) in the AA. There was no significant difference in BMI (26.0 ± 4.6 vs. 28.0 ± 6.7 kg/m{sup 2}), PC (103 ± 7 vs. 104 ± 10 cm{sup 2}) and TSA (92 ± 15 vs. 91 ± 19 cm{sup 2}) between 100 kV and 120 kV group. Mean vascular attenuation was significantly higher in the 100 kV compared to the 120 kV group (AA 438 vs. 354 HU, PA 460 vs. 349 HU, LCA 370 vs. 299 HU all p < 0.001). SNR was not significantly different, even after adjusting for patient size. Radiation dose was significantly lower in the 100 kV group (10.7 ± 4.1 vs. 20.7 ± 10.7 mSv; p < 0.001). 100 kV TRO-CTA is feasible in normal-to-overweight patients while maintaining image quality and achieving substantial dose reduction. (orig.)

  19. FCNN-MR: A Parallel Instance Selection Method Based on Fast Condensed Nearest Neighbor Rule

    OpenAIRE

    Lu Si; Jie Yu; Shasha Li; Jun Ma; Lei Luo; Qingbo Wu; Yongqi Ma; Zhengji Liu

    2017-01-01

    Instance selection (IS) technique is used to reduce the data size to improve the performance of data mining methods. Recently, to process very large data set, several proposed methods divide the training set into some disjoint subsets and apply IS algorithms independently to each subset. In this paper, we analyze the limitation of these methods and give our viewpoint about how to divide and conquer in IS procedure. Then, based on fast condensed nearest neighbor (FCNN) rul...

  20. Spaceborne construction and operations planning - Decision rules for selecting EVA, telerobot, and combined work-systems

    Science.gov (United States)

    Smith, Jeffrey H.

    1992-01-01

    An approach is presented for selecting an appropriate work-system for performing construction and operations tasks by humans and telerobots. The decision to use extravehicular activity (EVA) performed by astronauts, extravehicular robotics (EVR), or a combination of EVA and EVR is determined by the ratio of the marginal costs of EVA, EVR, and IVA. The approach proposed here is useful for examining cost trade-offs between tasks and performing trade studies of task improvement techniques (human or telerobotic).

  1. New approach to nonleptonic weak interactions. I. Derivation of asymptotic selection rules for the two-particle weak ground-state-hadron matrix elements

    International Nuclear Information System (INIS)

    Tanuma, T.; Oneda, S.; Terasaki, K.

    1984-01-01

    A new approach to nonleptonic weak interactions is presented. It is argued that the presence and violation of the Vertical BarΔIVertical Bar = 1/2 rule as well as those of the quark-line selection rules can be explained in a unified way, along with other fundamental physical quantities [such as the value of g/sub A/(0) and the smallness of the isoscalar nucleon magnetic moments], in terms of a single dynamical asymptotic ansatz imposed at the level of observable hadrons. The ansatz prescribes a way in which asymptotic flavor SU(N) symmetry is secured levelwise for a certain class of chiral algebras in the standard QCD model. It yields severe asymptotic constraints upon the two-particle hadronic matrix elements of nonleptonic weak Hamiltonians as well as QCD currents and their charges. It produces for weak matrix elements the asymptotic Vertical BarΔIVertical Bar = 1/2 rule and its charm counterpart for the ground-state hadrons, while for strong matrix elements quark-line-like approximate selection rules. However, for the less important weak two-particle vertices involving higher excited states, the Vertical BarΔIVertical Bar = 1/2 rule and its charm counterpart are in general violated, providing us with an explicit source of the violation of these selection rules in physical processes

  2. Individualized radiation dose control in 256-slice CT coronary angiography (CTCA) in retrospective ECG-triggered helical scans: Using a measure of body size to adjust tube current selection

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jing-Lei, E-mail: lijinglei80@126.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Huang, Mei-Ping, E-mail: huang_meiping@yahoo.com.cn [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Liang, Chang-Hong, E-mail: cjr.lchh@vip.163.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Zhao, Zhen-Jun, E-mail: junabc2006@hotmail.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Liu, Hui, E-mail: liuhuijiujiu@gmail.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Cui, Yan-Hai, E-mail: yanhai_cui@126.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Liu, Qi-Shun, E-mail: liuqishun@yeah.net [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Zhang, Jin-E., E-mail: zhjine@yahoo.com.cn [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Yang, Lin, E-mail: yanglin001517@163.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Ivanc, Thomas B., E-mail: Thomas.ivanc@philips.com [CT Clinical Science, Philips Healthcare, Highland Heights, OH (United States); Yanof, Jeffrey H., E-mail: Jeffrey.yanof@philips.com [CT Clinical Science, Philips Healthcare, Highland Heights, OH (United States)

    2012-11-15

    Purpose: To reduce radiation dose for retrospective ECG-triggered helical 256-slice CTCA by determining an optimal body size index to prospectively adjust tube current. Methods: 102 consecutive patients with suspected CAD underwent retrospective ECG-triggered CTCA using 256-slice CT scanner. Six body size indexes including BMI, nipple level (NL) bust, thoracic anteroposterior diameter at NL, chest circumference (CC) at NL, left main and right coronary artery (RCA) origin level were measured and their correlation with noise was evaluated using linear regression. An equation was developed to use this index to adjust tube current. Additional 102 consecutive patients were scanned with the index-based mA s adjustment. A t-test for independent samples was used to compare radiation dose levels with and without the index-based mA s selection method. Results: Linear regression indicated that CC RCA had the best correlation with noise (R{sup 2} = 0.603). Effective radiation dose was reduced from 16.6 {+-} 0.9 to 9.8 {+-} 2.7 mSv (p < 0.01), i.e. 40.9% lower dose with the CC RCA-adapted tube current method. The image quality scores indicated no significant difference with and without the size-based mA s selection method. Conclusion: An accessible measure of body size, such as CC RCA, can be used to adapt tube current for individualized radiation dose control.

  3. Individualized radiation dose control in 256-slice CT coronary angiography (CTCA) in retrospective ECG-triggered helical scans: Using a measure of body size to adjust tube current selection

    International Nuclear Information System (INIS)

    Li, Jing-Lei; Huang, Mei-Ping; Liang, Chang-Hong; Zhao, Zhen-Jun; Liu, Hui; Cui, Yan-Hai; Liu, Qi-Shun; Zhang, Jin-E.; Yang, Lin; Ivanc, Thomas B.; Yanof, Jeffrey H.

    2012-01-01

    Purpose: To reduce radiation dose for retrospective ECG-triggered helical 256-slice CTCA by determining an optimal body size index to prospectively adjust tube current. Methods: 102 consecutive patients with suspected CAD underwent retrospective ECG-triggered CTCA using 256-slice CT scanner. Six body size indexes including BMI, nipple level (NL) bust, thoracic anteroposterior diameter at NL, chest circumference (CC) at NL, left main and right coronary artery (RCA) origin level were measured and their correlation with noise was evaluated using linear regression. An equation was developed to use this index to adjust tube current. Additional 102 consecutive patients were scanned with the index-based mA s adjustment. A t-test for independent samples was used to compare radiation dose levels with and without the index-based mA s selection method. Results: Linear regression indicated that CC RCA had the best correlation with noise (R 2 = 0.603). Effective radiation dose was reduced from 16.6 ± 0.9 to 9.8 ± 2.7 mSv (p < 0.01), i.e. 40.9% lower dose with the CC RCA-adapted tube current method. The image quality scores indicated no significant difference with and without the size-based mA s selection method. Conclusion: An accessible measure of body size, such as CC RCA, can be used to adapt tube current for individualized radiation dose control.

  4. Helical Tomotherapy Quality Assurance

    International Nuclear Information System (INIS)

    Balog, John; Soisson, Emilie

    2008-01-01

    Helical tomotherapy uses a dynamic delivery in which the gantry, treatment couch, and multileaf collimator leaves are all in motion during treatment. This results in highly conformal radiotherapy, but the complexity of the delivery is partially hidden from the end-user because of the extensive integration and automation of the tomotherapy control systems. This presents a challenge to the medical physicist who is expected to be both a system user and an expert, capable of verifying relevant aspects of treatment delivery. A related issue is that a clinical tomotherapy planning system arrives at a customer's site already commissioned by the manufacturer, not by the clinical physicist. The clinical physicist and the manufacturer's representative verify the commissioning at the customer site before acceptance. Theoretically, treatment could begin immediately after acceptance. However, the clinical physicist is responsible for the safe and proper use of the machine. In addition, the therapists and radiation oncologists need to understand the important machine characteristics before treatment can proceed. Typically, treatment begins about 2 weeks after acceptance. This report presents an overview of the tomotherapy system. Helical tomotherapy has unique dosimetry characteristics, and some of those features are emphasized. The integrated treatment planning, delivery, and patient-plan quality assurance process is described. A quality assurance protocol is proposed, with an emphasis on what a clinical medical physicist could and should check. Additionally, aspects of a tomotherapy quality assurance program that could be checked automatically and remotely because of its inherent imaging system and integrated database are discussed

  5. A NEW FRAMEWORK FOR GEOSPATIAL SITE SELECTION USING ARTIFICIAL NEURAL NETWORKS AS DECISION RULES: A CASE STUDY ON LANDFILL SITES

    Directory of Open Access Journals (Sweden)

    S. K. M. Abujayyab

    2015-10-01

    Full Text Available This paper briefly introduced the theory and framework of geospatial site selection (GSS and discussed the application and framework of artificial neural networks (ANNs. The related literature on the use of ANNs as decision rules in GSS is scarce from 2000 till 2015. As this study found, ANNs are not only adaptable to dynamic changes but also capable of improving the objectivity of acquisition in GSS, reducing time consumption, and providing high validation. ANNs make for a powerful tool for solving geospatial decision-making problems by enabling geospatial decision makers to implement their constraints and imprecise concepts. This tool offers a way to represent and handle uncertainty. Specifically, ANNs are decision rules implemented to enhance conventional GSS frameworks. The main assumption in implementing ANNs in GSS is that the current characteristics of existing sites are indicative of the degree of suitability of new locations with similar characteristics. GSS requires several input criteria that embody specific requirements and the desired site characteristics, which could contribute to geospatial sites. In this study, the proposed framework consists of four stages for implementing ANNs in GSS. A multilayer feed-forward network with a backpropagation algorithm was used to train the networks from prior sites to assess, generalize, and evaluate the outputs on the basis of the inputs for the new sites. Two metrics, namely, confusion matrix and receiver operating characteristic tests, were utilized to achieve high accuracy and validation. Results proved that ANNs provide reasonable and efficient results as an accurate and inexpensive quantitative technique for GSS.

  6. Magnetic field-induced modification of selection rules for Rb D 2 line monitored by selective reflection from a vapor nanocell

    Science.gov (United States)

    Klinger, Emmanuel; Sargsyan, Armen; Tonoyan, Ara; Hakhumyan, Grant; Papoyan, Aram; Leroy, Claude; Sarkisyan, David

    2017-08-01

    Magnetic field-induced giant modification of the probabilities of five transitions of 5S1 / 2,Fg = 2 → 5P3 / 2,Fe = 4 of 85Rb and three transitions of 5S1 / 2,Fg = 1 → 5P3 / 2,Fe = 3 of 87Rb forbidden by selection rules for zero magnetic field has been observed experimentally and described theoretically for the first time. For the case of excitation with circularly-polarized (σ+) laser radiation, the probability of Fg = 2,mF = - 2 → Fe = 4,mF = - 1 transition becomes the largest among the seventeen transitions of 85Rb Fg = 2 → Fe = 1,2,3,4 group, and the probability of Fg = 1, mF = - 1 → Fe = 3,mF = 0 transition becomes the largest among the nine transitions of 87Rb Fg = 1 → Fe = 0,1,2,3 group, in a wide range of magnetic field 200-1000 G. Complete frequency separation of individual Zeeman components was obtained by implementation of derivative selective reflection technique with a 300 nm-thick nanocell filled with Rb, allowing formation of narrow optical resonances. Possible applications are addressed. The theoretical model is well consistent with the experimental results.

  7. Employing Helicity Amplitudes for Resummation

    NARCIS (Netherlands)

    Moult, I.; Stewart, I.W.; Tackmann, F.J.; Waalewijn, W.J.

    2015-01-01

    Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are

  8. LARGE-SCALE MAGNETIC HELICITY FLUXES ESTIMATED FROM MDI MAGNETIC SYNOPTIC CHARTS OVER THE SOLAR CYCLE 23

    International Nuclear Information System (INIS)

    Yang Shangbin; Zhang Hongqi

    2012-01-01

    To investigate the characteristics of large-scale and long-term evolution of magnetic helicity with solar cycles, we use the method of Local Correlation Tracking to estimate the magnetic helicity evolution over solar cycle 23 from 1996 to 2009 using 795 MDI magnetic synoptic charts. The main results are as follows: the hemispheric helicity rule still holds in general, i.e., the large-scale negative (positive) magnetic helicity dominates the northern (southern) hemisphere. However, the large-scale magnetic helicity fluxes show the same sign in both hemispheres around 2001 and 2005. The global, large-scale magnetic helicity flux over the solar disk changes from a negative value at the beginning of solar cycle 23 to a positive value at the end of the cycle, while the net accumulated magnetic helicity is negative in the period between 1996 and 2009.

  9. LARGE-SCALE MAGNETIC HELICITY FLUXES ESTIMATED FROM MDI MAGNETIC SYNOPTIC CHARTS OVER THE SOLAR CYCLE 23

    Energy Technology Data Exchange (ETDEWEB)

    Yang Shangbin; Zhang Hongqi, E-mail: yangshb@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, 100012 Beijing (China)

    2012-10-10

    To investigate the characteristics of large-scale and long-term evolution of magnetic helicity with solar cycles, we use the method of Local Correlation Tracking to estimate the magnetic helicity evolution over solar cycle 23 from 1996 to 2009 using 795 MDI magnetic synoptic charts. The main results are as follows: the hemispheric helicity rule still holds in general, i.e., the large-scale negative (positive) magnetic helicity dominates the northern (southern) hemisphere. However, the large-scale magnetic helicity fluxes show the same sign in both hemispheres around 2001 and 2005. The global, large-scale magnetic helicity flux over the solar disk changes from a negative value at the beginning of solar cycle 23 to a positive value at the end of the cycle, while the net accumulated magnetic helicity is negative in the period between 1996 and 2009.

  10. Flexible helical yarn swimmers.

    Science.gov (United States)

    Zakharov, A P; Leshansky, A M; Pismen, L M

    2016-09-01

    We investigate the motion of a flexible Stokesian flagellar swimmer realised as a yarn made of two intertwined elastomer fibres, one active, that can reversibly change its length in response to a local excitation causing transition to the nematic state or swelling, and the other one, a passive isotropic elastomer with identical mechanical properties. A propagating chemical wave may provide an excitation mechanism ensuring a constant length of the excited region. Generally, the swimmer moves along a helical trajectory, and the propagation and rotation velocity are very sensitive to the ratio of the excited region to the pitch of the yarn, as well as to the size of a carried load. External excitation by a moving actuating beam is less effective, unless the direction of the beam is adjusted to rotation of the swimmer.

  11. LHD helical divertor

    International Nuclear Information System (INIS)

    Ohyabu, N.; Watanabe, T.; Ji Hantao

    1993-07-01

    The Large Helical Device (LHD) now under construction is a heliotron/torsatron device with a closed divertor system. The edge LHD magnetic structure has been studied in detail. A peculiar feature of the configuration is existence of edge surface layers, a complicated three dimensional magnetic structure which does not, however, seem to hamper the expected divertor functions. Two divertor operational modes are being considered for the LHD experiment, high density, cold radiative divertor operation as a safe heat removal scheme and high temperature divertor plasma operation. In the latter operation, a divertor plasma with temperature of a few kev, generated by efficient pumping, expects to lead to significant improvement in core plasma confinement. Conceptual designs of the LHD divertor components are under way. (author)

  12. A theory for bioinorganic chemical reactivity of oxometal complexes and analogous oxidants: the exchange and orbital-selection rules.

    Science.gov (United States)

    Usharani, Dandamudi; Janardanan, Deepa; Li, Chunsen; Shaik, Sason

    2013-02-19

    unpaired electrons on the metal center. Thus, we introduce the exchange-enhanced reactivity (EER) principle, which predicts the preferred spin state during oxidation reactions, the dependence of the barrier on the number of unpaired electrons in the TS, and the dependence of the deformation energy of the reactants on the spin state. We complement EER with orbital-selection rules, which predict the structure of the preferred TS and provide a handy theory of bioinorganic oxidative reactions. These rules show how EER provides a Hund's Rule for chemical reactivity: EER controls the reactivity landscape for a great variety of transition-metal complexes and substrates. Among many reactivity patterns explained, EER rationalizes the abundance of high-spin oxoiron(IV) complexes in enzymes that carry out bond activation of the strongest bonds. The concepts used in this Account might also be applicable in other areas such as in f-block chemistry and excited-state reactivity of 4d and 5d OMCs.

  13. Evolution of sexual dimorphism and Rensch’s rule in the beetle genus Limnebius (Hydraenidae: is sexual selection opportunistic?

    Directory of Open Access Journals (Sweden)

    Andrey Rudoy

    2017-03-01

    Full Text Available Sexual size dimorphism (SSD is widespread among animals, with larger females usually attributed to an optimization of resources in reproduction and larger males to sexual selection. A general pattern in the evolution of SSD is Rensch’s rule, which states that SSD increases with body size in species with larger males but decreases when females are larger. We studied the evolution of SSD in the genus Limnebius (Coleoptera, Hydraenidae, measuring SSD and male genital size and complexity of ca. 80% of its 150 species and reconstructing its evolution in a molecular phylogeny with 71 species. We found strong support for a higher evolutionary lability of male body size, which had an overall positive allometry with respect to females and higher evolutionary rates measured over the individual branches of the phylogeny. Increases in SSD were associated to increases in body size, but there were some exceptions with an increase associated to changes in only one sex. Secondary sexual characters (SSC in the external morphology of males appeared several times independently, generally on species that had already increased their size. There was an overall significant correlation between SSD, male body size and male genital size and complexity, although some lineages with complex genitalia had low SSD, and some small species with complex genitalia had no SSD. Our results suggest that the origin of the higher evolutionary variance of male body size may be due to lack of constraints rather than to sexual selection, that may start to act in species with already larger males due to random variation.

  14. Theoretical aspects of magnetic helicity

    International Nuclear Information System (INIS)

    Hammer, J.H.

    1985-01-01

    The magnetic helicity, usually defined as K=integralA.Bdv, where A is the vector potential and B the magnetic field, measures the topological linkage of magnetic fluxes. Helicity manifests itself in the twistedness and knottedness of flux tubes. Its significance is that it is an ideal MHD invariant. While the helicity formalism has proven very useful in understanding reversed field pinch and spheromak behavior, some problems exist in applying the method consistently for complex (e.g., toroidal) conductor geometries or in situations where magnetic flux penetrates conducting walls. Recent work has attempted to generalize K to allow for all possible geometries

  15. Dose reduction in coronary artery imaging with 64-row multi-slice helical CT with body mass index-dependent mA selection

    International Nuclear Information System (INIS)

    Gao Jianhua; Wang Guisheng; Zheng Jingchen; Li Jianying; Sun Xianchang; Gao Caihong; Dai Ruping

    2008-01-01

    Objective: To evaluate the robustness of body mass index (BMI) adapted tube current selection method for obtaining consistent image quality in MSCT coronary artery imaging. Methods: Initially one hundred patients in the control group (C group) underwent cardiac scans using GE 64-row VCT with standard scan protocol (640 mA, 120 kV, 0.35 sec, body bowtie, C 2 filter). Noise measurement was obtained for each patient using the average of three consecutive slices in the ascending aorta with ROI of 10 mm x 10 mm to establish the relationship between BMI, desired image noise (IN) and required mA. An excel table was established to predict the required mA to achieve a desired IN for each patient with different BMI. A second group of one hundred cardiac patients (L group) was scanned with BMI-adapted mA from the table to evaluate the practicability of this method. BMI, IN, CT dose index (CTDI), effective dose (ED) were all recorded. Results: For the control group of 100 patients, the mean values and standard deviations of image quality score (IQS), BMI, IN and ED were 3.71±0.54, 25.08±2.63, 24.56±5.03 and (17.63±1.68) mSv (with range of 15-22 mSv). Regression analysis indicated linear relationship between BMI and image noise with fixed mA. Using the relationship between tube current and image noise and noise ratio between large bowtie and cardiac bowtie, the following equation for the required tube current Xma to achieve present image noise of INa for patient with certain BMI value when using cardiac bowtie could be then obtained: Xma=Fma x [(k 1 x BMI + c 1 )/Ina] 2 , where Fma=640 mA, k 1 =1.033, c 1 = -3.2, INa=27 in the study. (2) For the patients in L group, the mean values and standard deviations of IQS, BMI, and IN were 3.69±0.53, 25.07±2.91, and 26.61±3.44, respectively. The average tube current used was (469.95±113.45) mA, depending on patient's BMI values. The average effectively dose was (9.08±2.25) mSv. There was no statistically difference between the

  16. Nasonia Parasitic Wasps Escape from Haller's Rule by Diphasic, Partially Isometric Brain-Body Size Scaling and Selective Neuropil Adaptations

    NARCIS (Netherlands)

    Groothuis, Jitte; Smid, Hans M.

    2017-01-01

    Haller's rule states that brains scale allometrically with body size in all animals, meaning that relative brain size increases with decreasing body size. This rule applies both on inter- and intraspecific comparisons. Only 1 species, the extremely small parasitic wasp Trichogramma evanescens, is

  17. Godbillon Vey Helicity and Magnetic Helicity in Magnetohydrodynamics

    Science.gov (United States)

    Webb, G. M.; Hu, Q.; Anco, S.; Zank, G. P.

    2017-12-01

    The Godbillon-Vey invariant arises in homology theory, and algebraic topology, where conditions for a layered family of 2D surfaces forms a 3D manifold were elucidated. The magnetic Godbillon-Vey helicity invariant in magnetohydrodynamics (MHD) is a helicity invariant that occurs for flows, in which the magnetic helicity density hm= A\\cdotB=0 where A is the magnetic vector potential and B is the magnetic induction. Our purpose is to elucidate the evolution of the magnetic Godbillon-Vey field η =A×B/|A|2 and the Godbillon-Vey helicity hgv}= η \\cdot∇ × η in general MHD flows in which the magnetic helicity hm≠q 0. It is shown that hm acts as a source term in the Godbillon-Vey helicity transport equation, in which hm is coupled to hgv via the shear tensor of the background flow. The transport equation for hgv depends on the electric field potential ψ , which is related to the gauge for A, which takes its simplest form for the advected A gauge in which ψ =A\\cdot u where u is the fluid velocity.

  18. Helicity multiplexed broadband metasurface holograms.

    Science.gov (United States)

    Wen, Dandan; Yue, Fuyong; Li, Guixin; Zheng, Guoxing; Chan, Kinlong; Chen, Shumei; Chen, Ming; Li, King Fai; Wong, Polis Wing Han; Cheah, Kok Wai; Pun, Edwin Yue Bun; Zhang, Shuang; Chen, Xianzhong

    2015-09-10

    Metasurfaces are engineered interfaces that contain a thin layer of plasmonic or dielectric nanostructures capable of manipulating light in a desirable manner. Advances in metasurfaces have led to various practical applications ranging from lensing to holography. Metasurface holograms that can be switched by the polarization state of incident light have been demonstrated for achieving polarization multiplexed functionalities. However, practical application of these devices has been limited by their capability for achieving high efficiency and high image quality. Here we experimentally demonstrate a helicity multiplexed metasurface hologram with high efficiency and good image fidelity over a broad range of frequencies. The metasurface hologram features the combination of two sets of hologram patterns operating with opposite incident helicities. Two symmetrically distributed off-axis images are interchangeable by controlling the helicity of the input light. The demonstrated helicity multiplexed metasurface hologram with its high performance opens avenues for future applications with functionality switchable optical devices.

  19. Study of quark line selection rule (OZI rule) in the hadron processes. 3. Study of the OZI rule in production of φ and ω mesons in diffractive p N interactions at the energy of 70 GeV

    International Nuclear Information System (INIS)

    Balats, M.Ya.; Vavilov, D.V.; Viktorov, V.A.

    1996-01-01

    Ratio of cross sections for pφ- and pω-production in diffractive p N-interactions was measured with the Sphinx facility at the energy of E p = 70 GeV. Results of this work demonstrate significant OZI rule violation in proton-induced reactions. 12 refs., 8 figs

  20. Employing helicity amplitudes for resummation

    International Nuclear Information System (INIS)

    Moult, Ian; Stewart, Iain W.; Tackmann, Frank J.; Waalewijn, Wouter J.; Amsterdam Univ.

    2015-08-01

    Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are directly given in terms of color-ordered helicity amplitudes. Using this basis allows one to seamlessly combine fixed-order helicity amplitudes at any order they are known with a resummation of higher-order logarithmic corrections. In particular, the virtual loop amplitudes can be employed in factorization theorems to make predictions for exclusive jet cross sections without the use of numerical subtraction schemes to handle real-virtual infrared cancellations. We also discuss matching onto SCET in renormalization schemes with helicities in 4- and d-dimensions. To demonstrate that our helicity operator basis is easy to use, we provide an explicit construction of the operator basis, as well as results for the hard matching coefficients, for pp → H+0,1,2 jets, pp → W/Z/γ+0,1,2 jets, and pp → 2,3 jets. These operator bases are completely crossing symmetric, so the results can easily be applied to processes with e + e - and e - p collisions.

  1. Neutrino helicity flips via electroweak interactions

    International Nuclear Information System (INIS)

    Gaemers, K.J.F.; Gandhi, R.; Lattimer, J.M.; Department of Earth and Space Sciences, State University of New York, Stony Brook, New York 11794)

    1989-01-01

    Electroweak mechanisms via which neutrinos may flip helicity are examined in detail. Exact and approximate expressions for a variety of flip processes relevant in astrophysics and cosmology, mediated by W, Z, and γ exchange, including their interference, are derived for both Dirac and Majorana neutrinos (with emphasis on the former). It is shown that in general flip and nonflip cross sections differ by more than just a multiplicative factor of m/sub ν/ 2 /4E/sub ν/ 2 contrary to what might be expected and that this additional dependence on helicities can be significant. It is also shown that within the context of the standard model with massive neutrinos, for νe yields νe scattering, σ/sub Z//sup flip//σ/sub γ//sup flip/ ∼ 10 4 , independent of particle masses and energies to a good approximation. As an application, using some general considerations and the fact that the observed bar nu/sub e/ burst from SN 1987A lasted several seconds, these weak-interaction flip cross sections are used to rule out μ and tau neutrino masses above 30 keV. Finally, some other consequences for astrophysics in general and supernovae in particular are briefly discussed

  2. Pulling Helices inside Bacteria: Imperfect Helices and Rings

    Science.gov (United States)

    Allard, Jun F.; Rutenberg, Andrew D.

    2009-04-01

    We study steady-state configurations of intrinsically-straight elastic filaments constrained within rod-shaped bacteria that have applied forces distributed along their length. Perfect steady-state helices result from axial or azimuthal forces applied at filament ends, however azimuthal forces are required for the small pitches observed for MreB filaments within bacteria. Helix-like configurations can result from distributed forces, including coexistence between rings and imperfect helices. Levels of expression and/or bundling of the polymeric protein could mediate this coexistence.

  3. Transport barrier in Helical system

    International Nuclear Information System (INIS)

    Ida, Katsumi

    1998-01-01

    Experiments on the transport barrier in Helical plasmas are reviewed. There are two mechanisms of transport improvement, that results in the formation of the transport barrier. One is the improvement of neoclassical transport by reducing the ripple loss with radial electric field, which exist only in helical plasma. The other is the improvement of anomalous transport due to the suppression of fluctuations associated with a radial electric field shear both in tokamak and helical plasma. The formation of the transport barrier can be triggered by the radial electric field shear associated with the transition of the radial electric field (L/H transition or ion-electron root transition) or the peaked density or the optimization of magnetic field shear. The mechanisms of transport barrier formation are also discussed. (author). 60 refs

  4. Generalized helicity and Beltrami fields

    Energy Technology Data Exchange (ETDEWEB)

    Buniy, Roman V., E-mail: roman.buniy@gmail.com [Schmid College of Science, Chapman University, Orange, CA 92866 (United States); Isaac Newton Institute, University of Cambridge, Cambridge, CB3 0EH (United Kingdom); Kephart, Thomas W., E-mail: tom.kephart@gmail.com [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Isaac Newton Institute, University of Cambridge, Cambridge, CB3 0EH (United Kingdom)

    2014-05-15

    We propose covariant and non-abelian generalizations of the magnetic helicity and Beltrami equation. The gauge invariance, variational principle, conserved current, energy–momentum tensor and choice of boundary conditions elucidate the subject. In particular, we prove that any extremal of the Yang–Mills action functional 1/4 ∫{sub Ω}trF{sub μν}F{sup μν}d{sup 4}x subject to the local constraint ε{sup μναβ}trF{sub μν}F{sub αβ}=0 satisfies the covariant non-abelian Beltrami equation. -- Highlights: •We introduce the covariant non-abelian helicity and Beltrami equation. •The Yang–Mills action and instanton term constraint lead to the Beltrami equation. •Solutions of the Beltrami equation conserve helicity.

  5. Generalized helicity and Beltrami fields

    International Nuclear Information System (INIS)

    Buniy, Roman V.; Kephart, Thomas W.

    2014-01-01

    We propose covariant and non-abelian generalizations of the magnetic helicity and Beltrami equation. The gauge invariance, variational principle, conserved current, energy–momentum tensor and choice of boundary conditions elucidate the subject. In particular, we prove that any extremal of the Yang–Mills action functional 1/4 ∫ Ω trF μν F μν d 4 x subject to the local constraint ε μναβ trF μν F αβ =0 satisfies the covariant non-abelian Beltrami equation. -- Highlights: •We introduce the covariant non-abelian helicity and Beltrami equation. •The Yang–Mills action and instanton term constraint lead to the Beltrami equation. •Solutions of the Beltrami equation conserve helicity

  6. Toroidal helical quartz forming machine

    International Nuclear Information System (INIS)

    Hanks, K.W.; Cole, T.R.

    1977-01-01

    The Scyllac fusion experimental machine used 10 cm diameter smooth bore discharge tubes formed into a simple toroidal shape prior to 1974. At about that time, it was discovered that a discharge tube was required to follow the convoluted shape of the load coil. A machine was designed and built to form a fused quartz tube with a toroidal shape. The machine will accommodate quartz tubes from 5 cm to 20 cm diameter forming it into a 4 m toroidal radius with a 1 to 5 cm helical displacement. The machine will also generate a helical shape on a linear tube. Two sets of tubes with different helical radii and wavelengths have been successfully fabricated. The problems encountered with the design and fabrication of this machine are discussed

  7. Helical axis stellarator equilibrium model

    International Nuclear Information System (INIS)

    Koniges, A.E.; Johnson, J.L.

    1985-02-01

    An asymptotic model is developed to study MHD equilibria in toroidal systems with a helical magnetic axis. Using a characteristic coordinate system based on the vacuum field lines, the equilibrium problem is reduced to a two-dimensional generalized partial differential equation of the Grad-Shafranov type. A stellarator-expansion free-boundary equilibrium code is modified to solve the helical-axis equations. The expansion model is used to predict the equilibrium properties of Asperators NP-3 and NP-4. Numerically determined flux surfaces, magnetic well, transform, and shear are presented. The equilibria show a toroidal Shafranov shift

  8. Resonant helical fields in tokamaks

    International Nuclear Information System (INIS)

    Okano, V.

    1990-01-01

    Poincare maps of magnetic field lines of a toroidal helical system were made. The magnetic field is a linear superposition of the magnetic fields produced by a toroidal plasma in equilibrium and by external helical currents. Analytical expression for the Poincare maps was no obtained since the magnetic field do not have symmetry. In order to obtain the maps, the equation minus derivative of l vector times B vector = 0 was numerically integrated. In the Poincare maps, the principal and the secondary magnetic island were observed. (author)

  9. Helical system. History and current state of helical research

    International Nuclear Information System (INIS)

    Yokoyama, Masayuki

    2017-01-01

    This paper described the following: (1) history of nuclear fusion research of Japan's original heliotron method, (2) worldwide development of nuclear fusion research based on helical system such as stellarator, and (3) worldwide meaning of large helical device (LHD) aiming to demonstrate the steady-state performance of heliotron type in the parameter area extrapolable to the core plasma, and research results of LHD. LHD demonstrated that the helical system is excellent in steady operation performance at the world's most advanced level. In an experiment using deuterium gas in 2017, LHD achieved to reach 120 million degrees of ion temperature, which is one index of nuclear fusion condition, demonstrated the realization of high-performance plasma capable of extrapolating to future nuclear fusion reactors, and established the foundation for full-scale research toward the realization of nuclear fusion reactor. Besides experimental research, this paper also described the helical-type stationary nuclear fusion prototype reactor, FFHR-d1, which was based on progress of large-scale simulation at the world's most advanced level. A large-scale superconducting stellarator experimental device, W7-X, with the same scale as LHD, started experiment in December 2015, whose current state is also touched on here. (A.O.)

  10. Helicity and evanescent waves. [Energy transport velocity, helicity, Lorentz transformation

    Energy Technology Data Exchange (ETDEWEB)

    Agudin, J L; Platzeck, A M [La Plata Univ. Nacional (Argentina); Albano, J R [Instituto de Astronomia y Fisica del Espacio, Buenos Aires, Argentina

    1978-02-20

    It is shown that the projection of the angular momentum of a circularly polarized electromagnetic evanescent wave along the mean velocity of energy transport (=helicity) can be reverted by a Lorentz transformation, in spite of the fact that this velocity is c.

  11. Self-assembly of a double-helical complex of sodium.

    Science.gov (United States)

    Bell, T W; Jousselin, H

    1994-02-03

    Spontaneous self-organization of helical and multiple-helical molecular structures occurs on several levels in living organisms. Key examples are alpha-helical polypeptides, double-helical nucleic acids and helical protein structures, including F-actin, microtubules and the protein sheath of the tobacco mosaic virus. Although the self-assembly of double-helical transition-metal complexes bears some resemblance to the molecular organization of double-stranded DNA, selection between monohelical, double-helical and triple-helical structures is determined largely by the size and geometrical preference of the tightly bound metal. Here we present an example of double-helical assembly induced by the weaker and non-directional interactions of an alkali-metal ion with an organic ligand that is pre-organized into a coil. We have characterized the resulting complex by two-dimensional NMR and fast-atom-bombardment mass spectrometry. These results provide a step toward the creation of molecular tubes or ion channels consisting of intertwined coils.

  12. Helical coil alignment in the advanced toroidal facility

    International Nuclear Information System (INIS)

    Taylor, D.J.; Cole, M.J.; Johnson, R.L.; Nelson, B.E.; Warwick, J.E.; Whitson, J.C.

    1985-01-01

    This paper presents a brief overview of the helical coil design concept, detailed descriptions of the method for installation and alignment, and discussions of segment installation and alignment equipment. Alignment is accomplished by optical methods using electronic theodolites connected to a microcomputer to form a coordinate measurement system. The coordinate measurement system is described in detail, along with target selection and fixturing for manipulation of the helical coil segments during installation. In addition, software is described including vendor-supplied software used in the coordinate measurement system and in-house-developed software used to calibrate segment and positioning fixture motion. 2 refs., 8 figs

  13. Parameterization and measurements of helical magnetic fields

    International Nuclear Information System (INIS)

    Fischer, W.; Okamura, M.

    1997-01-01

    Magnetic fields with helical symmetry can be parameterized using multipole coefficients (a n , b n ). We present a parameterization that gives the familiar multipole coefficients (a n , b n ) for straight magnets when the helical wavelength tends to infinity. To measure helical fields all methods used for straight magnets can be employed. We show how to convert the results of those measurements to obtain the desired helical multipole coefficients (a n , b n )

  14. Applications of 2D helical vortex dynamics

    DEFF Research Database (Denmark)

    Okulov, Valery; Sørensen, Jens Nørkær

    2010-01-01

    In the paper, we show how the assumption of helical symmetry in the context of 2D helical vortices can be exploited to analyse and to model various cases of rotating flows. From theory, examples of three basic applications of 2D dynamics of helical vortices embedded in flows with helical symmetry...... of the vorticity field are addressed. These included some of the problems related to vortex breakdown, instability of far wakes behind rotors and vortex theory of ideal rotors....

  15. ICRF heating on helical devices

    International Nuclear Information System (INIS)

    Rasmussen, D.A.; Lyon, J.F.; Hoffman, D.J.; Murakami, M.; England, A.C.; Wilgen, J.B.; Jaeger, E.F.; Wang, C.; Batchelor, D.B.

    1995-01-01

    Ion cyclotron range of frequency (ICRF) heating is currently in use on CHS and W7-AS and is a major element of the heating planned for steady state helical devices. In helical devices, the lack of a toroidal current eliminates both disruptions and the need for ICRF current drive, simplifying the design of antenna structures as compared to tokamak applications. However the survivability of plasma facing components and steady state cooling issues are directly applicable to tokamak devices. Results from LHD steady state experiments should be available on a time scale to strongly influence the next generation of steady state tokamak experiments. The helical plasma geometry provides challenges not faced with tokamak ICRF heating, including the potential for enhanced fast ion losses, impurity accumulation, limited access for antenna structures, and open magnetic field lines in the plasma edge. The present results and near term plans provide the basis for steady state ICRF heating of larger helical devices. An approach which includes direct electron, mode conversion, ion minority and ion Bernstein wave heating addresses these issues

  16. ICRF heating on helical devices

    International Nuclear Information System (INIS)

    Rasmussen, D.A.; Lyon, J.F.; Hoffman, D.J.

    1995-01-01

    Ion cyclotron range of frequency (ICRF) heating is currently in use on CHS and W7AS and is a major element of the heating planned for steady state helical devices. In helical devices, the lack of a toroidal current eliminates both disruptions and the need for ICRF current drive, simplifying the design of antenna structures as compared to tokamak applications. However the survivability of plasma facing components and steady state cooling issues are directly applicable to tokamak devices. Results from LHD steady state experiments should be available on a time scale to strongly influence the next generation of steady state tokamak experiments. The helical plasma geometry provides challenges not faced with tokamak ICRF heating, including the potential for enhanced fast ion losses, impurity accumulation, limited access for antenna structures, and open magnetic field lines in the plasma edge. The present results and near term plans provide the basis for steady state ICRF heating of larger helical devices. An approach which includes direct electron, mode conversion, ion minority and ion Bernstein wave heating addresses these issues

  17. The helical tomotherapy thread effect

    International Nuclear Information System (INIS)

    Kissick, M.W.; Fenwick, J.; James, J.A.; Jeraj, R.; Kapatoes, J.M.; Keller, H.; Mackie, T.R.; Olivera, G.; Soisson, E.T.

    2005-01-01

    Inherent to helical tomotherapy is a dose variation pattern that manifests as a 'ripple' (peak-to-trough relative to the average). This ripple is the result of helical beam junctioning, completely unique to helical tomotherapy. Pitch is defined as in helical CT, the couch travel distance for a complete gantry rotation relative to the axial beam width at the axis of rotation. Without scattering or beam divergence, an analytical posing of the problem as a simple integral predicts minima near a pitch of 1/n where n is an integer. A convolution-superposition dose calculator (TomoTherapy, Inc.) included all the physics needed to explore the ripple magnitude versus pitch and beam width. The results of the dose calculator and some benchmark measurements demonstrate that the ripple has sharp minima near p=0.86(1/n). The 0.86 factor is empirical and caused by a beam junctioning of the off-axis dose profiles which differ from the axial profiles as well as a long scatter tail of the profiles at depth. For very strong intensity modulation, the 0.86 factor may vary. The authors propose choosing particular minima pitches or using a second delivery that starts 180 deg off-phase from the first to reduce these ripples: 'Double threading'. For current typical pitches and beam widths, however, this effect is small and not clinically important for most situations. Certain extremely large field or high pitch cases, however, may benefit from mitigation of this effect

  18. Selecting short-statured children needing growth hormone testing: Derivation and validation of a clinical decision rule

    Directory of Open Access Journals (Sweden)

    Bréart Gérard

    2008-07-01

    Full Text Available Abstract Background Numerous short-statured children are evaluated for growth hormone (GH deficiency (GHD. In most patients, GH provocative tests are normal and are thus in retrospect unnecessary. Methods A retrospective cohort study was conducted to identify predictors of growth hormone (GH deficiency (GHD in children seen for short stature, and to construct a very sensitive and fairly specific predictive tool to avoid unnecessary GH provocative tests. GHD was defined by the presence of 2 GH concentration peaks Results The initial study included 167 patients, 36 (22% of whom had GHD, including 5 (3% with certain GHD. Independent predictors of GHD were: growth rate Conclusion We have derived and performed an internal validation of a highly sensitive decision rule that could safely help to avoid more than 2/3 of the unnecessary GH tests. External validation of this rule is needed before any application.

  19. Dosimetric aspects of breast radiotherapy with three-dimensional and intensity-modulated radiotherapy helical tomotherapy planning modules

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Poonam [Department of Human Oncology, University of Wisconsin-Madison, Madison, WI (United States); Service of Radiation Therapy, University of Wisconsin Aspirus Cancer Center, Wisconsin Rapids, WI (United States); Yan, Yue, E-mail: yyan5@mdanderson.org [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX (United States); Ignatowski, Tasha [Service of Radiation Therapy, University of Wisconsin Aspirus Cancer Center, Wisconsin Rapids, WI (United States); Olson, Anna [Department of Human Oncology, University of Wisconsin-Madison, Madison, WI (United States); Service of Radiation Therapy, University of Wisconsin Aspirus Cancer Center, Wisconsin Rapids, WI (United States)

    2017-04-01

    In this work, we investigated the dosimetric differences between the intensity-modulated radiotherapy (IMRT) plans and the three-dimensional (3D) helical plans based on the TomoTherapy system. A total of 15 patients with supine setup were randomly selected from the data base. For patients with lumpectomy planning target volume (PTV), regional lymph nodes were also included as part of the target. For dose sparing, the significant differences between the helical IMRT and helical 3D were only found in the heart and contralateral breast. For the dose to the heart, helical IMRT reduced the maximum point dose by 6.98 Gy compared to the helical 3D plan (p = 0.01). For contralateral breast, the helical IMRT plans significantly reduced the maximum point dose by 5.6 Gy compared to the helical 3D plan. However, compared to the helical 3D plan, the helical IMRT plan increased the volume for lower dose (13.08% increase in V{sub 5} {sub Gy}, p = 0.01). In general, there are no significant differences in dose sparing between helical IMRT and helical 3D plans.

  20. Dosimetric aspects of breast radiotherapy with three-dimensional and intensity-modulated radiotherapy helical tomotherapy planning modules

    International Nuclear Information System (INIS)

    Yadav, Poonam; Yan, Yue; Ignatowski, Tasha; Olson, Anna

    2017-01-01

    In this work, we investigated the dosimetric differences between the intensity-modulated radiotherapy (IMRT) plans and the three-dimensional (3D) helical plans based on the TomoTherapy system. A total of 15 patients with supine setup were randomly selected from the data base. For patients with lumpectomy planning target volume (PTV), regional lymph nodes were also included as part of the target. For dose sparing, the significant differences between the helical IMRT and helical 3D were only found in the heart and contralateral breast. For the dose to the heart, helical IMRT reduced the maximum point dose by 6.98 Gy compared to the helical 3D plan (p = 0.01). For contralateral breast, the helical IMRT plans significantly reduced the maximum point dose by 5.6 Gy compared to the helical 3D plan. However, compared to the helical 3D plan, the helical IMRT plan increased the volume for lower dose (13.08% increase in V 5 Gy , p = 0.01). In general, there are no significant differences in dose sparing between helical IMRT and helical 3D plans.

  1. 6,6″-Dimethyl-2,2':6',2″-terpyridine revisited: new fluorescent silver(I) helicates with in vitro antiproliferative activity via selective nucleoli targeting.

    Science.gov (United States)

    Fik, Marta A; Gorczyński, Adam; Kubicki, Maciej; Hnatejko, Zbigniew; Fedoruk-Wyszomirska, Agnieszka; Wyszko, Eliza; Giel-Pietraszuk, Małgorzata; Patroniak, Violetta

    2014-10-30

    6,6″-Dimethyl-2,2':6',2″-terpyridine ligand (L) reacts in equimolar ratio with Ag(I) ions what results in formation of dinuclear double helicates, which differ in terms of framework and complexity in accordance to counterions and solvent applied. Obtained complexes were thoroughly studied in terms of their biological activity, with the positive antiproliferative outcome on three human cancer cell lines: human breast cancer (T47D), human cervical carcinoma (HeLa) and human lung cancer (A-549). Performed DNA binding experiments showed that given Ag(I) species specifically interact with DNA double helix via intercalation and were visualized by confocal microscopy to specifically bind to the nuclei. All newly synthesized helical systems exhibit promising antimicrobial activity against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacterial strains. Spectrophotometric properties were described as fulfilment of structural studies of newly presented complexes confirming their helical structure in solution. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  2. EVOLUTION OF MAGNETIC HELICITY AND ENERGY SPECTRA OF SOLAR ACTIVE REGIONS

    International Nuclear Information System (INIS)

    Zhang, Hongqi; Brandenburg, Axel; Sokoloff, D. D.

    2016-01-01

    We adopt an isotropic representation of the Fourier-transformed two-point correlation tensor of the magnetic field to estimate the magnetic energy and helicity spectra as well as current helicity spectra of two individual active regions (NOAA 11158 and NOAA 11515) and the change of the spectral indices during their development as well as during the solar cycle. The departure of the spectral indices of magnetic energy and current helicity from 5/3 are analyzed, and it is found that it is lower than the spectral index of the magnetic energy spectrum. Furthermore, the fractional magnetic helicity tends to increase when the scale of the energy-carrying magnetic structures increases. The magnetic helicity of NOAA 11515 violates the expected hemispheric sign rule, which is interpreted as an effect of enhanced field strengths at scales larger than 30–60 Mm with opposite signs of helicity. This is consistent with the general cycle dependence, which shows that around the solar maximum the magnetic energy and helicity spectra are steeper, emphasizing the large-scale field

  3. EVOLUTION OF MAGNETIC HELICITY AND ENERGY SPECTRA OF SOLAR ACTIVE REGIONS

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongqi [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Brandenburg, Axel [Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-10691 Stockholm (Sweden); Sokoloff, D. D., E-mail: hzhang@bao.ac.cn [Department of Physics, Moscow University, 119992 Moscow (Russian Federation)

    2016-03-10

    We adopt an isotropic representation of the Fourier-transformed two-point correlation tensor of the magnetic field to estimate the magnetic energy and helicity spectra as well as current helicity spectra of two individual active regions (NOAA 11158 and NOAA 11515) and the change of the spectral indices during their development as well as during the solar cycle. The departure of the spectral indices of magnetic energy and current helicity from 5/3 are analyzed, and it is found that it is lower than the spectral index of the magnetic energy spectrum. Furthermore, the fractional magnetic helicity tends to increase when the scale of the energy-carrying magnetic structures increases. The magnetic helicity of NOAA 11515 violates the expected hemispheric sign rule, which is interpreted as an effect of enhanced field strengths at scales larger than 30–60 Mm with opposite signs of helicity. This is consistent with the general cycle dependence, which shows that around the solar maximum the magnetic energy and helicity spectra are steeper, emphasizing the large-scale field.

  4. Influence of drill helical direction on exit damage development in drilling carbon fiber reinforced plastic

    Science.gov (United States)

    Bai, Y.; Jia, Z. Y.; Wang, F. J.; Fu, R.; Guo, H. B.; Cheng, D.; Zhang, B. Y.

    2017-06-01

    Drilling is inevitable for CFRP components’ assembling process in the aviation industry. The exit damage frequently occurs and affects the load carrying capacity of components. Consequently, it is of great urgency to enhance drilling exit quality on CFRP components. The article aims to guide the reasonable choice of drill helical direction and effectively reduce exit damage. Exit observation experiments are carried out with left-hand helical, right-hand helical and straight one-shot drill drilling T800S CFRP laminates separately. The development rules of exit damage and delamination factor curves are obtained. Combined with loading conditions and fracture modes of push-out burrs, and thrust force curves, the influence of drill helical direction on exit damage development is derived. It is found that the main fracture modes for left-hand helical, right-hand helical, and straight one-shot drill are mode I, extrusive fracture, mode III respectively. Among them, mode III has the least effect on exit damage development. Meanwhile, the changing rate of thrust force is relative slow for right-hand helical and straight one-shot drill in the thrust force increasing phase of stage II, which is disadvantaged for exit damage development. Therefore, straight one-shot drill’s exit quality is the best.

  5. PRODUCTIVITY OF SOLAR FLARES AND MAGNETIC HELICITY INJECTION IN ACTIVE REGIONS

    International Nuclear Information System (INIS)

    Park, Sung-hong; Wang Haimin; Chae, Jongchul

    2010-01-01

    The main objective of this study is to better understand how magnetic helicity injection in an active region (AR) is related to the occurrence and intensity of solar flares. We therefore investigate the magnetic helicity injection rate and unsigned magnetic flux, as a reference. In total, 378 ARs are analyzed using SOHO/MDI magnetograms. The 24 hr averaged helicity injection rate and unsigned magnetic flux are compared with the flare index and the flare-productive probability in the next 24 hr following a measurement. In addition, we study the variation of helicity over a span of several days around the times of the 19 flares above M5.0 which occurred in selected strong flare-productive ARs. The major findings of this study are as follows: (1) for a sub-sample of 91 large ARs with unsigned magnetic fluxes in the range from (3-5) x 10 22 Mx, there is a difference in the magnetic helicity injection rate between flaring ARs and non-flaring ARs by a factor of 2; (2) the GOES C-flare-productive probability as a function of helicity injection displays a sharp boundary between flare-productive ARs and flare-quiet ones; (3) the history of helicity injection before all the 19 major flares displayed a common characteristic: a significant helicity accumulation of (3-45) x 10 42 Mx 2 during a phase of monotonically increasing helicity over 0.5-2 days. Our results support the notion that helicity injection is important in flares, but it is not effective to use it alone for the purpose of flare forecast. It is necessary to find a way to better characterize the time history of helicity injection as well as its spatial distribution inside ARs.

  6. Generalized helicity and its time derivative

    International Nuclear Information System (INIS)

    Jarboe, T.R.; Marklin, G.J.

    1985-01-01

    Spheromaks can be sustained against resistive decay by helicity injection because they tend to obey the minimum energy principle. This principle states that a plasma-laden magnetic configuration will relax to a state of minimum energy subject to the constraint that the magnetic helicity is conserved. Use of helicity as a constraint on the minimization of energy was first proposed by Woltjer in connection with astrophysical phenomena. Helicity does decay on the resistive diffusion time. However, if helicity is created and made to flow continuoiusly into a confinement geometry, these additional linked fluxes can relax and sustain the configuration indefinitely against the resistive decay. In this paper we will present an extension of the definition of helicity to include systems where B vector can penetrate the boundary and the penetration can be varying in time. We then discuss the sustainment of RFPs and spheromaks in terms of helicity injection

  7. A helical scintillating fiber hodoscope

    CERN Document Server

    Altmeier, M; Bisplinghoff, J; Bissel, T; Bollmann, R; Busch, M; Büsser, K; Colberg, T; Demiroers, L; Diehl, O; Dohrmann, F; Engelhardt, H P; Eversheim, P D; Felden, O; Gebel, R; Glende, M; Greiff, J; Gross, A; Gross-Hardt, R; Hinterberger, F; Jahn, R; Jeske, M; Jonas, E; Krause, H; Lahr, U; Langkau, R; Lindemann, T; Lindlein, J; Maier, R; Maschuw, R; Mayer-Kuckuck, T; Meinerzhagen, A; Naehle, O; Pfuff, M; Prasuhn, D; Rohdjess, H; Rosendaal, D; Von Rossen, P; Sanz, B; Schirm, N; Schulz-Rojahn, M; Schwarz, V; Scobel, W; Thomas, S; Trelle, H J; Weise, E; Wellinghausen, A; Wiedmann, W; Woller, K; Ziegler, R

    1999-01-01

    A novel scintillating fiber hodoscope in helically cylindric geometry has been developed for detection of low multiplicity events of fast protons and other light charged particles in the internal target experiment EDDA at the Cooler Synchrotron COSY. The hodoscope consists of 640 scintillating fibers (2.5 mm diameter), arranged in four layers surrounding the COSY beam pipe. The fibers are helically wound in opposing directions and read out individually using 16-channel photomultipliers connected to a modified commercial encoding system. The detector covers an angular range of 9 deg. <= THETA<=72 deg. and 0 deg. <=phi (cursive,open) Greek<=360 deg. in the lab frame. The detector length is 590 mm, the inner diameter 161 mm. Geometry and granularity of the hodoscope afford a position resolution of about 1.3 mm. The detector design took into consideration a maximum of reliability and a minimum of maintenance. An LED array may be used for monitoring purposes. (author)

  8. Helicity formalism and spin effects

    International Nuclear Information System (INIS)

    Anselmino, M.; Caruso, F.; Piovano, U.

    1990-01-01

    The helicity formalism and the technique to compute amplitudes for interaction processes involving leptons, quarks, photons and gluons are reviewed. Explicit calculations and examples of exploitation of symmetry properties are shown. The formalism is then applied to the discussion of several hadronic processes and spin effects: the experimental data, when related to the properties of the elementary constituent interactions, show many not understood features. Also the nucleon spin problem is briefly reviewed. (author)

  9. Radiation characteristics of helical tomotherapy

    International Nuclear Information System (INIS)

    Jeraj, Robert; Mackie, Thomas R.; Balog, John; Olivera, Gustavo; Pearson, Dave; Kapatoes, Jeff; Ruchala, Ken; Reckwerdt, Paul

    2004-01-01

    Helical tomotherapy is a dedicated intensity modulated radiation therapy (IMRT) system with on-board imaging capability (MVCT) and therefore differs from conventional treatment units. Different design goals resulted in some distinctive radiation field characteristics. The most significant differences in the design are the lack of flattening filter, increased shielding of the collimators, treatment and imaging operation modes and narrow fan beam delivery. Radiation characteristics of the helical tomotherapy system, sensitivity studies of various incident electron beam parameters and radiation safety analyses are presented here. It was determined that the photon beam energy spectrum of helical tomotherapy is similar to that of more conventional radiation treatment units. The two operational modes of the system result in different nominal energies of the incident electron beam with approximately 6 MeV and 3.5 MeV in the treatment and imaging modes, respectively. The off-axis mean energy dependence is much lower than in conventional radiotherapy units with less than 5% variation across the field, which is the consequence of the absent flattening filter. For the same reason the transverse profile exhibits the characteristic conical shape resulting in a 2-fold increase of the beam intensity in the center. The radiation leakage outside the field was found to be negligible at less than 0.05% because of the increased shielding of the collimators. At this level the in-field scattering is a dominant source of the radiation outside the field and thus a narrow field treatment does not result in the increased leakage. The sensitivity studies showed increased sensitivity on the incident electron position because of the narrow fan beam delivery and high sensitivity on the incident electron energy, as common to other treatment systems. All in all, it was determined that helical tomotherapy is a system with some unique radiation characteristics, which have been to a large extent

  10. Chaotic coordinates for the Large Helical Device

    Energy Technology Data Exchange (ETDEWEB)

    Hudson, S. R., E-mail: shudson@pppl.gov [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States); Suzuki, Y. [National Institute for Natural Sciences, National Institute for Fusion Sciences, 322-6 Oroshi, Toki, 509-5292 (Japan)

    2014-10-15

    The theory of quadratic-flux-minimizing (QFM) surfaces is reviewed, and numerical techniques that allow high-order QFM surfaces to be efficiently constructed for experimentally relevant, non-integrable magnetic fields are described. As a practical example, the chaotic edge of the magnetic field in the Large Helical Device (LHD) is examined. A precise technique for finding the boundary surface is implemented, the hierarchy of partial barriers associated with the near-critical cantori is constructed, and a coordinate system, which we call chaotic coordinates, that is based on a selection of QFM surfaces is constructed that simplifies the description of the magnetic field, so that flux surfaces become “straight” and islands become “square.”.

  11. Magnetic helicity and active filament configuration

    Science.gov (United States)

    Romano, P.; Zuccarello, F.; Poedts, S.; Soenen, A.; Zuccarello, F. P.

    2009-11-01

    Context: The role of magnetic helicity in active filament formation and destabilization is still under debate. Aims: Although active filaments usually show a sigmoid shape and a twisted configuration before and during their eruption, it is unclear which mechanism leads to these topologies. In order to provide an observational contribution to clarify these issues, we describe a filament evolution whose characteristics seem to be directly linked to the magnetic helicity transport in corona. Methods: We applied different methods to determine the helicity sign and the chirality of the filament magnetic field. We also computed the magnetic helicity transport rate at the filament footpoints. Results: All the observational signatures provided information on the positive helicity and sinistral chirality of the flux rope containing the filament material: its forward S shape, the orientation of its barbs, the bright and dark threads at 195 Å. Moreover, the magnetic helicity transport rate at the filament footpoints showed a clear accumulation of positive helicity. Conclusions: The study of this event showed a correspondence between several signatures of the sinistral chirality of the filament and several evidences of the positive magnetic helicity of the filament magnetic field. We also found that the magnetic helicity transported along the filament footpoints showed an increase just before the change of the filament shape observed in Hα images. We argued that the photospheric regions where the filament was rooted might be the preferential ways where the magnetic helicity was injected along the filament itself and where the conditions to trigger the eruption were yielded.

  12. New formulae for magnetic relative helicity and field line helicity

    Science.gov (United States)

    Aly, Jean-Jacques

    2018-01-01

    We consider a magnetic field {B} occupying the simply connected domain D and having all its field lines tied to the boundary S of D. We assume here that {B} has a simple topology, i.e., the mapping {M} from positive to negative polarity areas of S associating to each other the two footpoints of any magnetic line, is continuous. We first present new formulae for the helicity H of {B} relative to a reference field {{B}}r having the same normal component {B}n on S, and for its field line helicity h relative to a reference vector potential {{C}}r of {{B}}r. These formulae make immediately apparent the well known invariance of these quantities under all the ideal MHD deformations that preserve the positions of the footpoints on S. They express indeed h and H either in terms of {M} and {B}n, or in terms of the values on S of a pair of Euler potentials of {B}. We next show that, for a specific choice of {{C}}r, the field line helicity h of {B} fully characterizes the magnetic mapping {M} and then the topology of the lines. Finally, we give a formula that describes the rate of change of h in a situation where the plasma moves on the perfectly conducting boundary S without changing {B}n and/or non-ideal processes, described by an unspecified term {N} in Ohm’s law, are at work in some parts of D.

  13. Institute for Fusion Research and Large Helical Device program

    International Nuclear Information System (INIS)

    Iiyoshi, Atsuo

    1989-01-01

    In the research on nuclear fusion, the final objective is to materialize nuclear fusion reactors, and for the purpose, it is necessary to cause nuclear combustion by making the plasma of higher than 100 million deg and confine it for a certain time. So far in various universities, the researches on diversified fusion processes have been advanced, but in February, 1986, the Science Council issued the report 'Nuclear fusion research in universities hereafter'. As the next large scale device, an external conductor system helical device was decided, and it is desirable to found the organization for joint utilization by national universities to promote the project. The researches on the other processes are continued by utilizing the existing facilitie. The reason of selecting a helical device is the data base of the researches carried out so far can be utilized sufficiently, it is sufficiently novel even after 10 years from now, and many researchers can be collected. The place of the research is Toki City, Gifu Prefecture, where the Institute of Plasma Physics, Nagoya University, is to be moved. The basic concept of the superconducting helical device project, the trend of nuclear fusion development in the world, the physical research using a helical system and so on are reported. (Kako, I.)

  14. MHD stability analysis of helical system plasmas

    International Nuclear Information System (INIS)

    Nakamura, Yuji

    2000-01-01

    Several topics of the MHD stability studies in helical system plasmas are reviewed with respect to the linear and ideal modes mainly. Difference of the method of the MHD stability analysis in helical system plasmas from that in tokamak plasmas is emphasized. Lack of the cyclic (symmetric) coordinate makes an analysis more difficult. Recent topic about TAE modes in a helical system is also described briefly. (author)

  15. Employing helicity amplitudes for resummation in SCET

    International Nuclear Information System (INIS)

    Moult, Ian; Stewart, Iain W.; Tackmann, Frank J.; Waalewijn, Wouter J.; Nikhef, Amsterdam

    2016-05-01

    Helicity amplitudes are the fundamental ingredients of many QCD calculations for multi-leg processes. We describe how these can seamlessly be combined with resummation in Soft-Collinear Effective Theory (SCET), by constructing a helicity operator basis for which the Wilson coefficients are directly given in terms of color-ordered helicity amplitudes. This basis is crossing symmetric and has simple transformation properties under discrete symmetries.

  16. Single-Sex Schools, Student Achievement, and Course Selection: Evidence from Rule-Based Student Assignments in Trinidad and Tobago

    OpenAIRE

    C. Kirabo Jackson

    2011-01-01

    Existing studies on single-sex schooling suffer from biases because students who attend single-sex schools differ in unmeasured ways from those who do not. In Trinidad and Tobago students are assigned to secondary schools based on an algorithm allowing one to address self-selection bias and estimate the causal effect of attending a single-sex school versus a similar coeducational school. While students (particularly females) with strong expressed preferences for single-sex schools benefit, mo...

  17. Amino acid pair- and triplet-wise groupings in the interior of α-helical segments in proteins.

    Science.gov (United States)

    de Sousa, Miguel M; Munteanu, Cristian R; Pazos, Alejandro; Fonseca, Nuno A; Camacho, Rui; Magalhães, A L

    2011-02-21

    A statistical approach has been applied to analyse primary structure patterns at inner positions of α-helices in proteins. A systematic survey was carried out in a recent sample of non-redundant proteins selected from the Protein Data Bank, which were used to analyse α-helix structures for amino acid pairing patterns. Only residues more than three positions apart from both termini of the α-helix were considered as inner. Amino acid pairings i, i+k (k=1, 2, 3, 4, 5), were analysed and the corresponding 20×20 matrices of relative global propensities were constructed. An analysis of (i, i+4, i+8) and (i, i+3, i+4) triplet patterns was also performed. These analysis yielded information on a series of amino acid patterns (pairings and triplets) showing either high or low preference for α-helical motifs and suggested a novel approach to protein alphabet reduction. In addition, it has been shown that the individual amino acid propensities are not enough to define the statistical distribution of these patterns. Global pair propensities also depend on the type of pattern, its composition and orientation in the protein sequence. The data presented should prove useful to obtain and refine useful predictive rules which can further the development and fine-tuning of protein structure prediction algorithms and tools. Copyright © 2010 Elsevier Ltd. All rights reserved.

  18. Folding control in cyclic peptides through N-methylation pattern selection: formation of antiparallel beta-sheet dimers, double reverse turns and supramolecular helices by 3alpha,gamma cyclic peptides.

    Science.gov (United States)

    Amorín, Manuel; Castedo, Luis; Granja, Juan R

    2008-01-01

    Peptide foldamers constitute a growing class of nanomaterials with potential applications in a wide variety of chemical, medical and technological fields. Here we describe the preparation and structural characteristics of a new class of cyclic peptide foldamers (3alpha,gamma-CPs) that, depending on their backbone N-methylation patterns and the medium, can either remain as flat rings that dimerize through arrays of hydrogen bonds of antiparallel beta-sheet type, or can fold into twisted double reverse turns that, in the case of double gamma-turns, associate in nonpolar solvents to form helical supramolecular structures. A 3alpha,gamma-CP consists of a number of multiples of a repeat unit made up of four amino acid residues of alternating chirality: three corresponding to alpha-amino acids and one to a gamma-amino acid (a cis-3-aminocycloalkanecarboxylic acid).

  19. New Classes of Quasi-helically Symmetric Stellarators

    International Nuclear Information System (INIS)

    Ku, L.P.; Boozer, A.H.

    2010-01-01

    New classes of quasi-helically symmetric stellarators with aspect ratios (le) 10 have been found which are stable to the perturbation of magnetohydrodynamic modes at plasma pressures of practical interest. These configurations have large rotational transform and good quality of flux surfaces. Characteristics of some selected examples are discussed in detail. The feasibility of using modular coils for these stellarators has been investigated. It is shown that practical designs for modular coils can be achieved.

  20. Impact of helical boundary conditions on nonlinear 3D magnetohydrodynamic simulations of reversed-field pinch

    International Nuclear Information System (INIS)

    Veranda, M; Bonfiglio, D; Cappello, S; Chacón, L; Escande, D F

    2013-01-01

    Helical self-organized reversed-field pinch (RFP) regimes emerge both numerically—in 3D visco-resistive magnetohydrodynamic (MHD) simulations—and experimentally, as in the RFX-mod device at high current (I P above 1 MA). These states, called quasi-single helicity (QSH) states, are characterized by the action of a MHD mode that impresses a quasi-helical symmetry to the system, thus allowing a high degree of magnetic chaos healing. This is in contrast with the multiple helicity (MH) states, where magnetic fluctuations create a chaotic magnetic field degrading the confinement properties of the RFP. This paper reports an extensive numerical study performed in the frame of 3D visco-resistive MHD which considers the effect of helical magnetic boundary conditions, i.e. of a finite value of the radial magnetic field at the edge (magnetic perturbation, MP). We show that the system can be driven to a selected QSH state starting from both spontaneous QSH and MH regimes. In particular, a high enough MP can force a QSH helical self-organization with a helicity different from the spontaneous one. Moreover, MH states can be turned into QSH states with a selected helicity. A threshold in the amplitude of MP is observed above which is able to influence the system. Analysis of the magnetic topology of these simulations indicates that the dominant helical mode is able to temporarily sustain conserved magnetic structures in the core of the plasma. The region occupied by conserved magnetic surfaces increases reducing secondary modes' amplitude to experimental-like values. (paper)

  1. Helicity in proton–proton elastic scattering and the spin structure of the pomeron

    Directory of Open Access Journals (Sweden)

    Carlo Ewerz

    2016-12-01

    Full Text Available We discuss different models for the spin structure of the nonperturbative pomeron: scalar, vector, and rank-2 symmetric tensor. The ratio of single-helicity-flip to helicity-conserving amplitudes in polarised high-energy proton–proton elastic scattering, known as the complex r5 parameter, is calculated for these models. We compare our results to experimental data from the STAR experiment. We show that the spin-0 (scalar pomeron model is clearly excluded by the data, while the vector pomeron is inconsistent with the rules of quantum field theory. The tensor pomeron is found to be perfectly consistent with the STAR data.

  2. Specific features of slow neutron coherent scattering by crystals with substitution impurities and selection rules for the mass operator of phonons

    International Nuclear Information System (INIS)

    Dzyub, I.P.; Kochmarskij, V.Z.

    1978-01-01

    The specific features of coherent slow-neutron scattering in the neighbourhood of the quasilocal oscillation (QLO) frequency are investigated. By means of the calculation for a simple cubic crystal containing substitutional impurities it is demonstrated that the dispersion curves are discontinuous in the QLO frequency range. This dispersion curve discontinuity is associated with one-phonon peak in the neighbourhood of the QLO frequency. The results of neutron scattering experiments on Crsub(1-x)Wsub(x) and Cusub(1-x)Ausub(x) solutions are then considered from this standpoint. Selection rules for the phonon mass operator are established which allow to determine the symmetry of QLO which contribute to the broadening and shift of one-phonon peaks in the directions of high symmetry, depending on the transfer neutron-momentum orientation with respect to the principal axes of a crystal

  3. Measurement of Electronic States of PbS Nanocrystal Quantum Dots Using Scanning Tunneling Spectroscopy: The Role of Parity Selection Rules in Optical Absorption

    Science.gov (United States)

    Diaconescu, Bogdan; Padilha, Lazaro A.; Nagpal, Prashant; Swartzentruber, Brian S.; Klimov, Victor I.

    2013-03-01

    We study the structure of electronic states in individual PbS nanocrystal quantum dots by scanning tunneling spectroscopy (STS) using one-to-two monolayer nanocrystal films treated with 1, 2-ethanedithiols (EDT). Up to six individual valence and conduction band states are resolved for a range of quantum dot sizes. The measured states’ energies are in good agreement with calculations using the k·p four-band envelope function formalism. A comparison of STS and optical absorption spectra indicates that some of the absorption features can only be explained by asymmetric transitions involving the states of different symmetries (e.g., S and P or P and D), which points towards the relaxation of the parity selection rules in these nanostructures. STS measurements also reveal a midgap feature, which is likely similar to one observed in previous charge transport studies of EDT-treated quantum dot films.

  4. Collagenolytic Matrix Metalloproteinase Activities toward Peptomeric Triple-Helical Substrates.

    Science.gov (United States)

    Stawikowski, Maciej J; Stawikowska, Roma; Fields, Gregg B

    2015-05-19

    Although collagenolytic matrix metalloproteinases (MMPs) possess common domain organizations, there are subtle differences in their processing of collagenous triple-helical substrates. In this study, we have incorporated peptoid residues into collagen model triple-helical peptides and examined MMP activities toward these peptomeric chimeras. Several different peptoid residues were incorporated into triple-helical substrates at subsites P3, P1, P1', and P10' individually or in combination, and the effects of the peptoid residues were evaluated on the activities of full-length MMP-1, MMP-8, MMP-13, and MMP-14/MT1-MMP. Most peptomers showed little discrimination between MMPs. However, a peptomer containing N-methyl Gly (sarcosine) in the P1' subsite and N-isobutyl Gly (NLeu) in the P10' subsite was hydrolyzed efficiently only by MMP-13 [nomenclature relative to the α1(I)772-786 sequence]. Cleavage site analysis showed hydrolysis at the Gly-Gln bond, indicating a shifted binding of the triple helix compared to the parent sequence. Favorable hydrolysis by MMP-13 was not due to sequence specificity or instability of the substrate triple helix but rather was based on the specific interactions of the P7' peptoid residue with the MMP-13 hemopexin-like domain. A fluorescence resonance energy transfer triple-helical peptomer was constructed and found to be readily processed by MMP-13, not cleaved by MMP-1 and MMP-8, and weakly hydrolyzed by MT1-MMP. The influence of the triple-helical structure containing peptoid residues on the interaction between MMP subsites and individual substrate residues may provide additional information about the mechanism of collagenolysis, the understanding of collagen specificity, and the design of selective MMP probes.

  5. Beta-helical polymers from isocyanopeptides

    NARCIS (Netherlands)

    Cornelissen, J.J.L.M.; Donners, J.J.J.M.; Gelder, de R.; Graswinckel, W.S.; Metselaar, G.A.; Rowan, A.E.; Sommerdijk, N.A.J.M.; Nolte, R.J.M.

    2001-01-01

    Polymerization of isocyanopeptides results in the formation of high molecular mass polymers that fold in a proteinlike fashion to give helical strands in which the peptide chains are arranged in ß-sheets. The ß-helical polymers retain their structure in water and unfold in a cooperative process at

  6. Magnetic islands created by resonant helical windings

    International Nuclear Information System (INIS)

    Fernandes, A.S.; Heller, M.V.; Caldas, I.L.

    1986-01-01

    The triggering of disruptive instabilities by resonant helical windings in large aspect-ratio tokamaks is associated to destruction of magnetic surfaces. The Chirikov condition is applied to estimate analytically the helical winding current thresholds for ergodization of the magnetic field lines. (Autor) [pt

  7. Helicity amplitudes for matter-coupled gravity

    International Nuclear Information System (INIS)

    Aldrovandi, R.; Novaes, S.F.; Spehler, D.

    1992-07-01

    The Weyl-van der Waerden spinor formalism is applied to the evaluation of helicity invariant amplitudes in the framework of linearized gravitation. The graviton couplings to spin-0, 1 - 2 , 1, and 3 - 2 particles are given, and, to exhibit the reach of this method, the helicity amplitudes for the process electron + positron → photon + graviton are obtained. (author)

  8. Stiffness versus architecture of single helical polyisocyanopeptides

    NARCIS (Netherlands)

    Buul, van A.M.; Schwartz, E.; Brocorens, P.; Koepf, M.; Beljonne, D.; Maan, J.C.; Christianen, P.C.M.; Kouwer, P.H.J.; Nolte, R.J.M.; Engelkamp, H.; Blank, K.; Rowan, A.E.

    2013-01-01

    Helical structures play a vital role in nature, offering mechanical rigidity, chirality and structural definition to biological systems. Little is known about the influence of the helical architecture on the intrinsic properties of polymers. Here, we offer an insight into the nano architecture of

  9. Dynamics of zonal flows in helical systems.

    Science.gov (United States)

    Sugama, H; Watanabe, T-H

    2005-03-25

    A theory for describing collisionless long-time behavior of zonal flows in helical systems is presented and its validity is verified by gyrokinetic-Vlasov simulation. It is shown that, under the influence of particles trapped in helical ripples, the response of zonal flows to a given source becomes weaker for lower radial wave numbers and deeper helical ripples while a high-level zonal-flow response, which is not affected by helical-ripple-trapped particles, can be maintained for a longer time by reducing their bounce-averaged radial drift velocity. This implies a possibility that helical configurations optimized for reducing neoclassical ripple transport can simultaneously enhance zonal flows which lower anomalous transport.

  10. Quantitative investigation of Raman selection rules and validation of the secular equation for trigonal LiNbO3

    International Nuclear Information System (INIS)

    Pezzotti, Giuseppe; Hagihara, Hirofumi; Zhu Wenliang

    2013-01-01

    Some theoretical aspects of the vibrational behaviour of trigonal lithium niobate (LiNbO 3 ) are studied and discussed in detail based on spectroscopic experimental assessments. Polarized Raman spectroscopy is systematically applied to retrieve the fundamental parameters governing the dependence of Raman intensity on crystallographic orientation, through quantitating the complete set of individual elements for the second-rank Raman tensors of the LiNbO 3 cell (C 3v (3m) point group, R3c space group). Moreover, computational algorithms are also explicitly constructed to describe the spectral shifts of the selected Raman bands when subjected to unknown stress fields. Accordingly, we have experimentally confirmed the validity of the secular equation for the trigonal cell and quantitatively substantiated its application through the determination of the full set of phonon deformation potentials for seven independent bands among those available in the LiNbO 3 vibrational spectrum. Finally, a brief discussion is offered about the significance of the presented characterizations in the technological field of LiNbO 3 devices, including the newly shown possibility of quantitatively and concurrently unfolding from polarized Raman spectra both crystallographic and mechanical information in their vectorial and tensorial nature, respectively. (paper)

  11. Topology of helical fluid flow

    DEFF Research Database (Denmark)

    Andersen, Morten; Brøns, Morten

    2014-01-01

    function for the topology of the streamline pattern in incompressible flows. On this basis, we perform a comprehensive study of the topology of the flow field generated by a helical vortex filament in an ideal fluid. The classical expression for the stream function obtained by Hardin (Hardin, J. C. 1982...... the zeroes of a single real function of one variable, and we show that three different flow topologies can occur, depending on a single dimensionless parameter. By including the self-induced velocity on the vortex filament by a localised induction approximation, the stream function is slightly modified...... and an extra parameter is introduced. In this setting two new flow topologies arise, but not more than two critical points occur for any combination of parameters....

  12. The quantum Hall effect helicity

    Energy Technology Data Exchange (ETDEWEB)

    Shrivastava, Keshav N., E-mail: keshav1001@yahoo.com [Department of Physics, University of Malaya, Kuala Lumpur 50603 (Malaysia); School of Physics, University of Hyderabad, Hyderabad 500046 (India)

    2015-04-16

    The quantum Hall effect in semiconductor heterostructures is explained by two signs in the angular momentum j=l±s and g=(2j+1)/(2l+1) along with the Landau factor (n+1/2). These modifications in the existing theories explain all of the fractional charges. The helicity which is the sign of the product of the linear momentum with the spin p.s plays an important role for the understanding of the data at high magnetic fields. In particular it is found that particles with positive sign in the spin move in one direction and those with negative sign move in another direction which explains the up and down stream motion of the particles.

  13. ALOHA: Automatic libraries of helicity amplitudes for Feynman diagram computations

    Science.gov (United States)

    de Aquino, Priscila; Link, William; Maltoni, Fabio; Mattelaer, Olivier; Stelzer, Tim

    2012-10-01

    We present an application that automatically writes the HELAS (HELicity Amplitude Subroutines) library corresponding to the Feynman rules of any quantum field theory Lagrangian. The code is written in Python and takes the Universal FeynRules Output (UFO) as an input. From this input it produces the complete set of routines, wave-functions and amplitudes, that are needed for the computation of Feynman diagrams at leading as well as at higher orders. The representation is language independent and currently it can output routines in Fortran, C++, and Python. A few sample applications implemented in the MADGRAPH 5 framework are presented. Program summary Program title: ALOHA Catalogue identifier: AEMS_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEMS_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: http://www.opensource.org/licenses/UoI-NCSA.php No. of lines in distributed program, including test data, etc.: 6094320 No. of bytes in distributed program, including test data, etc.: 7479819 Distribution format: tar.gz Programming language: Python2.6 Computer: 32/64 bit Operating system: Linux/Mac/Windows RAM: 512 Mbytes Classification: 4.4, 11.6 Nature of problem: An effcient numerical evaluation of a squared matrix element can be done with the help of the helicity routines implemented in the HELAS library [1]. This static library contains a limited number of helicity functions and is therefore not always able to provide the needed routine in the presence of an arbitrary interaction. This program provides a way to automatically create the corresponding routines for any given model. Solution method: ALOHA takes the Feynman rules associated to the vertex obtained from the model information (in the UFO format [2]), and multiplies it by the different wavefunctions or propagators. As a result the analytical expression of the helicity routines is obtained. Subsequently, this expression is

  14. Evidence for Mixed Helicity in Erupting Filaments

    Science.gov (United States)

    Muglach, K.; Wang, Y.-M.; Kliem, B.

    2009-09-01

    Erupting filaments are sometimes observed to undergo a rotation about the vertical direction as they rise. This rotation of the filament axis is generally interpreted as a conversion of twist into writhe in a kink-unstable magnetic flux rope. Consistent with this interpretation, the rotation is usually found to be clockwise (as viewed from above) if the post-eruption arcade has right-handed helicity, but counterclockwise if it has left-handed helicity. Here, we describe two non-active-region filament events recorded with the Extreme-Ultraviolet Imaging Telescope on the Solar and Heliospheric Observatory in which the sense of rotation appears to be opposite to that expected from the helicity of the post-event arcade. Based on these observations, we suggest that the rotation of the filament axis is, in general, determined by the net helicity of the erupting system, and that the axially aligned core of the filament can have the opposite helicity sign to the surrounding field. In most cases, the surrounding field provides the main contribution to the net helicity. In the events reported here, however, the helicity associated with the filament "barbs" is opposite in sign to and dominates that of the overlying arcade.

  15. Using Magnetic Helicity Diagnostics to Determine the Nature of Solar Active-Region Formation

    Science.gov (United States)

    Georgoulis, Manolis K.

    Employing a novel nonlinear force-free (NLFF) method that self-consistently infers instantaneous free magnetic-energy and relative magnetic-helicity budgets from single photospheric vector magnetograms, we recently constructed the magnetic energy-helicity (EH) diagram of solar active regions. The EH diagram implies dominant relative helicities of left-handed or right-handed chiralities for the great majority of active regions. The amplitude (budget) of these helicities scales monotonically with the free magnetic energy. This constructive, strongly preferential accumulation of a certain sense of magnetic helicity seems to disqualify recently proposed mechanisms relying on a largely random near-surface convection for the formation of the great majority of active regions. The existing qualitative formation mechanism for these regions remains the conventional Omega-loop emergence following a buoyant ascension from the bottom of the convection zone. However, exceptions to this rule include even eruptive active regions: NOAA AR 11283 is an obvious outlier to the EH diagram, involving significant free magnetic energy with a small relative magnetic helicity. Relying on a timeseries of vector magnetograms of this region, our methodology shows nearly canceling amounts of both senses of helicity and an overall course from a weakly left-handed to a weakly right-handed structure, in the course of which a major eruption occurs. For this and similarly behaving active regions the latest near-surface formation scenario might conceivably be employed successfully. Research partially supported by the EU Seventh Framework Programme under grant agreement No. PIRG07-GA-2010-268245 and by the European Union Social Fund (ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: Thales. Investing in knowledge society through the European Social Fund.

  16. Polymorphic transformation of helical flagella of bacteria

    Science.gov (United States)

    Lim, Sookkyung; Howard Berg Collaboration; William Ko Collaboration; Yongsam Kim Collaboration; Wanho Lee Collaboration; Charles Peskin Collaboration

    2016-11-01

    Bacteria such as E. coli swim in an aqueous environment by utilizing the rotation of flagellar motors and alternate two modes of motility, runs and tumbles. Runs are steady forward swimming driven by bundles of flagellar filaments whose motors are turning CCW; tumbles involve a reorientation of the direction of swimming triggered by motor reversals. During tumbling, the helical flagellum undergoes polymorphic transformations, which is a local change in helical pitch, helical radius, and handedness. In this work, we investigate the underlying mechanism of structural conformation and how this polymorphic transition plays a role in bacterial swimming. National Science Foundation.

  17. Modelling simple helically delivered dose distributions

    International Nuclear Information System (INIS)

    Fenwick, John D; Tome, Wolfgang A; Kissick, Michael W; Mackie, T Rock

    2005-01-01

    In a previous paper, we described quality assurance procedures for Hi-Art helical tomotherapy machines. Here, we develop further some ideas discussed briefly in that paper. Simple helically generated dose distributions are modelled, and relationships between these dose distributions and underlying characteristics of Hi-Art treatment systems are elucidated. In particular, we describe the dependence of dose levels along the central axis of a cylinder aligned coaxially with a Hi-Art machine on fan beam width, couch velocity and helical delivery lengths. The impact on these dose levels of angular variations in gantry speed or output per linear accelerator pulse is also explored

  18. Plasmoid behavior in helical plasmas

    International Nuclear Information System (INIS)

    Ishizaki, R.; Nakajima, N.

    2009-01-01

    Full text: It is well known that an ablation cloud; a high density and low temperature plasmoid, drifts to the lower field side in tokamak plasmas, which leads to a good performance on fueling in tokamak. Such a good performance, however, has not been obtained yet in the planar axis heliotron; Large Helical Device (LHD) experiments, even if a pellet has been injected from the high field side. The purpose of the study is to clarify the difference on the plasmoid motion between tokamak and LHD plasmas by using the MHD simulation including ablation processes. It is found in tokamaks that the drift motion is induced by a tire tube force and 1/R force in the major radius direction, and that the pressure and density of the plasmoid have oscillation due to fast compressional Alfven wave. On the other hand, the upper and lower portions surrounding the plasmoid center drift to the higher field side, because 1/R force by magnetic field becomes negative in the major radius direction since the magnetic field surrounding the plasmoid is accumulated by the extremely large ablation pressure and the magnetic pressure perturbation becomes positive. It is also found that the plasmoid does not drift when the perturbation of the plasmoid is small. In addition, the motion of the plasmoid is investigated in LHD plasmas in four cases that the plasmoids are initially located at the inner and outer sides of the torus on the vertically and horizontally elongated poloidal cross sections. The plasmoids drift to the lower field sides in all cases. However, in the case that it is located at the inner side of the torus on the horizontally elongated poloidal cross section, it is found that the plasmoid drifts in the negative direction of the major radius and subsequently drifts in the positive direction of it. In other words, the plasmoid finally drifts in the positive direction of the major radius the same as the plasmoid located at the outer side of the torus. This fact might be one of the

  19. Controllable synthesis of helical, straight, hollow and nitrogen-doped carbon nanofibers and their magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xun [State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructure, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Xu, Zheng, E-mail: zhengxu@nju.edu.cn [State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructure, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)

    2012-12-15

    Graphical abstract: The helical, straight and hollow carbon nanofibers can be selectively synthesized by adjusting either the reaction temperature or feed gas composition. Display Omitted Highlights: ► CNFs were synthesized via pyrolysis of acetylene on copper NPs. ► The helical, straight, hollow and N-doped CNFs can be selectively synthesized. ► The growth mechanism of different types of CNFs was proposed. -- Abstract: Carbon nanofibers (CNFs) with various morphologies were synthesized by catalytic pyrolysis of acetylene on copper nanoparticles which were generated from the in situ decomposition of copper acetylacetonate. The morphology of the pristine and acid-washed CNFs was investigated by field emission scanning electron microscope and high-resolution transmission electron microscope. Helical, straight and hollow CNFs can be selectively synthesized by adjusting either the reaction temperature or feed gas composition. The growth mechanism for these three types of CNFs was proposed.

  20. Dual phase helical CT: diagnosis value for early pancreatic carcinoma

    International Nuclear Information System (INIS)

    Shen Bingqi; Zhang Ling; Zheng Keguo; Xu Dasheng

    2006-01-01

    Objective: To study dual-phase helical CT for the evaluation of early pancreatic cacinoma. Methods: Dual-phase helical CT was performed on 21 patients with early pancreatic carcinoma. In the enhanced imaging the contrast material was intravenously injected in a dose of 1.5 ml/kg at a rate of 3 ml/s. The image acquisition of the lesion in pancreatic phase (PP) and portal venous phase (PVP) were started at 35 seconds and 65 seconds after the start of the injection respectively. The enhancement of normal pancreas and tumor during the two phases was observed and compared. All data were statistically analyzed. Results: Tumor-pancreas contrast was significantly greater in PP (45.16±113.23) HU than in PVP (23.15±12.44) HU (t=2.13, P<0.01). Conclusion: Dual-phase helical CT scan for pancreas, including the imaging of the pancreatic and portal , venous phase, can be applied as an optimal selection. It can delineate early pancreatic carcinoma clearly and provide more information for the diagnosis of the lesion. The tumor-pancreas contrast was much higher' in PP than in PVP. (authors)

  1. Diagnosis of the σ-, π- and (σ+π-Aromaticity by the Shape of the NICSzz-Scan Curves and Symmetry-Based Selection Rules

    Directory of Open Access Journals (Sweden)

    Constantinos A. Tsipis

    2010-03-01

    Full Text Available The NICSzz-scan curves of aromatic organic, inorganic and “all-metal” molecules in conjunction with symmetry-based selection rules provide efficient diagnostic tools of the σ-, π- and/or double (σ + π-aromaticity. The NICSzz-scan curves of σ-aromatic molecules are symmetric around the z-axis, having half-band widths approximately less than 3 Å with the induced diatropic ring current arising from Tx,y-allowed transitions involving exclusively σ-type molecular orbitals. Broad NICSzz-scan curves (half-band width approximately higher than 3 Å characterize double (σ + π-aromaticity, the chief contribution to the induced diatropic ring current arising from Tx,y-allowed transitions involving both σ- and π-type molecular orbitals. NICSzz-scan curves exhibiting two maxima at a certain distance above and below the molecular plane are typical for (σ + π-aromatics where the π-diatropic ring current overwhelms the σ-type one. In the absence of any contribution from the σ-diatropic ring current, the NICSzz(0 value is close to zero and the molecule exhibits pure π-aromaticity.

  2. Helicity and Filament Channels? The Straight Twist!

    Science.gov (United States)

    Antiochos, Spiro K.

    2010-01-01

    One of the most important and most puzzling features of the coronal magnetic field is that it appears to have smooth magnetic structure with little evidence for non-potentiality except at special locations, photospheric polarity inversions lines where the non-potentiality is observed as a filament channel. This characteristic feature of the closed-field corona is highly unexpected given that photospheric motions continuously tangle its magnetic field. Although reconnection can eliminate some of the injected structure, it cannot destroy the helicity, which should build up to produce observable complexity. We propose that an inverse cascade process transports the injected helicity from the interior of closed flux regions to their boundaries, polarity inversion lines, creating filament channels. We describe how the helicity is injected and transported and calculate the relevant rates. We argue that one process, helicity transport, can explain both the observed lack and presence of structure in the coronal magnetic field.

  3. Spin versus helicity in processes involving transversity

    CERN Document Server

    Mekhfi, Mustapha

    2011-01-01

    We construct the spin formalism in order to deal in a direct and natural way with processes involving transversity which are now of increasing popularity. The helicity formalism which is more appropriate for collision processes of definite helicity has been so far used also to manage processes with transversity, but at the price of computing numerous helicity amplitudes generally involving unnecessary kinematical variables.In a second step we work out the correspondence between both formalisms and retrieve in another way all results of the helicity formalism but in simpler forms.We then compute certain processes for comparison.A special process:the quark dipole magnetic moment is shown to be exclusively treated within the spin formalism as it is directly related to the transverse spin of the quark inside the baryon.

  4. Helical magnetized wiggler for synchrotron radiation laser

    International Nuclear Information System (INIS)

    Wang Mei; Park, S.Y.; Hirshfield, J.L.

    1999-01-01

    A helical magnetized iron wiggler has been built for a novel infrared synchrotron radiation laser (SRL) experiment. The wiggler consists of four periods of helical iron structure immersed in a solenoid field. This wiggler is to impart transverse velocity to a prebunched 6 MeV electron beam, and thus to obtain a desired high orbit pitch ratio for the SRL. Field tapering at beam entrance is considered and tested on a similar wiggler. Analytic and simulated characteristics of wigglers of this type are discussed and the performance of the fabricated wigglers is demonstrated experimentally. A 4.7 kG peak field was measured for a 6.4 mm air gap and a 5.4 cm wiggler period at a 20 kG solenoid field. The measured helical fields compare favorably with the analytical solution. This type of helical iron wigglers has the potential to be scaled to small periods with strong field amplitude

  5. Helical magnetized wiggler for synchrotron radiation laser

    CERN Document Server

    Wang Mei; Hirshfield, J L

    1999-01-01

    A helical magnetized iron wiggler has been built for a novel infrared synchrotron radiation laser (SRL) experiment. The wiggler consists of four periods of helical iron structure immersed in a solenoid field. This wiggler is to impart transverse velocity to a prebunched 6 MeV electron beam, and thus to obtain a desired high orbit pitch ratio for the SRL. Field tapering at beam entrance is considered and tested on a similar wiggler. Analytic and simulated characteristics of wigglers of this type are discussed and the performance of the fabricated wigglers is demonstrated experimentally. A 4.7 kG peak field was measured for a 6.4 mm air gap and a 5.4 cm wiggler period at a 20 kG solenoid field. The measured helical fields compare favorably with the analytical solution. This type of helical iron wigglers has the potential to be scaled to small periods with strong field amplitude.

  6. Using helical compressors for coke gas condensation

    Energy Technology Data Exchange (ETDEWEB)

    Privalov, V E; Rezunenko, Yu I; Lelyanov, N V; Zarnitzkii, G Eh; Gordienko, A A; Derebenko, I F; Venzhega, A G; Leonov, N P; Gorokhov, N N

    1982-08-01

    Coke oven gas compression is discussed. Presently used multilevel piston compressors are criticized. The paper recommends using helical machines which combine advantages of using volume condensing compressors and compact high-efficiency centrifugal machines. Two kinds of helical compressors are evaluated: dry and oil-filled; their productivities and coke oven gas chemical composition are analyzed. Experiments using helical compressors were undertaken at the Yasinovskii plant. Flowsheet of the installation is shown. Performance results are given in a table. For all operating conditions content of insolubles in oil compounds is found to be lower than the acceptable value (0.08%). Compressor productivity measurements with variable manifold pressure are evaluated. Figures obtained show that efficient condensation of raw coke oven gas is possible. Increasing oil-filled compressor productivity is recommended by decreasing amount of oil injected and simultaneously increasing rotation speed. The dry helical compressor with water seal is found to be most promising for raw coke oven gas condensation. (10 refs.)

  7. Helicity evolution at small x

    International Nuclear Information System (INIS)

    Kovchegov, Yuri V.; Pitonyak, Daniel; Sievert, Matthew D.

    2016-01-01

    We construct small-x evolution equations which can be used to calculate quark and anti-quark helicity TMDs and PDFs, along with the g 1 structure function. These evolution equations resum powers of α s ln 2  (1/x) in the polarization-dependent evolution along with the powers of α s ln (1/x) in the unpolarized evolution which includes saturation effects. The equations are written in an operator form in terms of polarization-dependent Wilson line-like operators. While the equations do not close in general, they become closed and self-contained systems of non-linear equations in the large-N c and large-N c   N f limits. As a cross-check, in the ladder approximation, our equations map onto the same ladder limit of the infrared evolution equations for the g 1 structure function derived previously by Bartels, Ermolaev and Ryskin http://dx.doi.org/10.1007/s002880050285.

  8. Dynamics of helicity transport and Taylor relaxation

    International Nuclear Information System (INIS)

    Diamond, P.H.; Malkov, M.

    2003-01-01

    A simple model of the dynamics of Taylor relaxation is derived using symmetry principles alone. No statistical closure approximations are invoked or detailed plasma model properties assumed. Notably, the model predicts several classes of nondiffusive helicity transport phenomena, including traveling nonlinear waves and superdiffusive turbulent pulses. A universal expression for the scaling of the effective magnetic Reynolds number of a system undergoing Taylor relaxation is derived. Some basic properties of intermittency in helicity transport are examined

  9. Multiple helical modes of vortex breakdown

    DEFF Research Database (Denmark)

    Sørensen, Jens Nørkær; Naumov, I. V.; Okulov, Valery

    2011-01-01

    Experimental observations of vortex breakdown in a rotating lid-driven cavity are presented. The results show that vortex breakdown for cavities with high aspect ratios is associated with the appearance of stable helical vortex multiplets. By using results from stability theory generalizing Kelvi......’s problem on vortex polygon stability, and systematically exploring the cavity flow, we succeeded in identifying two new stable vortex breakdown states consisting of triple and quadruple helical multiplets....

  10. On the helicity of open magnetic fields

    International Nuclear Information System (INIS)

    Prior, C.; Yeates, A. R.

    2014-01-01

    We reconsider the topological interpretation of magnetic helicity for magnetic fields in open domains, and relate this to the relative helicity. Specifically, our domains stretch between two parallel planes, and each of these ends may be magnetically open. It is demonstrated that, while the magnetic helicity is gauge-dependent, its value in any gauge may be physically interpreted as the average winding number among all pairs of field lines with respect to some orthonormal frame field. In fact, the choice of gauge is equivalent to the choice of reference field in the relative helicity, meaning that the magnetic helicity is no less physically meaningful. We prove that a particular gauge always measures the winding with respect to a fixed frame, and propose that this is normally the best choice. For periodic fields, this choice is equivalent to measuring relative helicity with respect to a potential reference field. However, for aperiodic fields, we show that the potential field can be twisted. We prove by construction that there always exists a possible untwisted reference field.

  11. Diffusion in a tokamak with helical magnetic cells

    International Nuclear Information System (INIS)

    Wakatani, Masahiro

    1975-05-01

    In a tokamak with helical magnetic cells produced by a resonant helical magnetic field, diffusion in the collisional regime is studied. The diffusion coefficient is greatly enhanced near the resonant surface even for a weak helical magnetic field. A theoretical model for disruptive instabilities based on the enhanced transport due to helical magnetic cells is discussed. This may explain experiments of the tokamak with resonant helical fields qualitatively. (author)

  12. Experimental study of selection rules following from the existence of two types of neutrinos; Etude experimentale des regles de selection decoulant de l'existence de deux types de neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Gaillard, J M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-05-15

    Interactions of high energy neutrinos with matter have been observed In the course of an experiment done in collaboration with G. Danby, K. Goulianos, L. M. Lederman, N. Mistry, M. Schwartz and J. Steinberger at the Brookhaven AGS. The neutrinos were produced mainly in the decay {pi}{sup {+-}} {yields} {mu}{sup {+-}} + {upsilon}({upsilon}-bar); the experiment leads to the conclusion that thee neutrinos are very likely different from the ones produced in beta decay reactions. We use the result of this experiment to study the selection rules applicable in the framework of a two neutrino theory. (author) [French] Nous avons observe l'interaction des neutrinos de haute energie avec la matiere au court dune experience effectuee en collaboration avec G. Danby, K. Goulianos, L. M. Lederman, N. Mistry, M. Schwartz et J. Steinberger sur l'accelerateur AGS du Brookhaven National Laboratory. Les neutrinos utilites provenaient principalement de la desintegration {pi}{sup {+-}} {yields} {mu}{sup {+-}} + {upsilon}({upsilon}-bar) l'experience conduit a la conclusion que ces neutrinos sont tres probablement differents de ceux produits par la desintegration beta. Nous utilisons les resultats de cette experience pour etudier quelles sont les regles de selection a utiliser dans le cadre d'une theorie a deux types de neutrinos. (auteur)

  13. The design and protocol of heat-sensitive moxibustion for knee osteoarthritis: a multicenter randomized controlled trial on the rules of selecting moxibustion location

    Directory of Open Access Journals (Sweden)

    Chi Zhenhai

    2010-06-01

    Full Text Available Abstract Background Knee osteoarthritis is a major cause of pain and functional limitation. Complementary and alternative medical approaches have been employed to relieve symptoms and to avoid the side effects of conventional medication. Moxibustion has been widely used to treat patients with knee osteoarthritis. Our past researches suggested heat-sensitive moxibustion might be superior to the conventional moxibustion. Our objective is to investigate the effectiveness of heat-sensitive moxibustion compared with conventional moxibustion or conventional drug treatment. Methods This study consists of a multi-centre (four centers in China, randomised, controlled trial with three parallel arms (A: heat-sensitive moxibustion; B: conventional moxibustion; C: conventional drug group. The moxibustion locations are different from A and B. Group A selects heat-sensitization acupoint from the region consisting of Yin Lingquan(SP9, Yang Lingquan(GB34, Liang Qiu(ST34, and Xue Hai (SP10. Meanwhile, fixed acupoints are used in group B, that is Xi Yan (EX-LE5 and He Ding (EX-LE2. The conventional drug group treats with intra-articular Sodium Hyaluronate injection. The outcome measures above will be assessed before the treatment, the 30 days of the last moxibustion session and 6 months after the last moxibustion session. Discussion This trial will utilize high quality trial methodologies in accordance with CONSORT guidelines. It will provide evidence for the effectiveness of moxibustion as a treatment for moderate and severe knee osteoarthritis. Moreover, the result will clarify the rules of heat-sensitive moxibustion location to improve the therapeutic effect with suspended moxibustion, and propose a new concept and a new theory of moxibustion to guide clinical practices. Trial Registration The trial is registered at Controlled Clinical Trials: ChiCTR-TRC-00000600.

  14. Integral dose delivered to normal brain with conventional intensity-modulated radiotherapy (IMRT) and helical tomotherapy IMRT during partial brain radiotherapy for high-grade gliomas with and without selective sparing of the hippocampus, limbic circuit and neural stem cell compartment

    International Nuclear Information System (INIS)

    Marsh, James C.; Ziel, Ellis G; Diaz, Aidnag Z; Turian, Julius V; Wendt, Julie A.; Gobole, Rohit

    2013-01-01

    We compared integral dose with uninvolved brain (ID brain ) during partial brain radiotherapy (PBRT) for high-grade glioma patients using helical tomotherapy (HT) and seven field traditional inverse-planned intensity-modulated radiotherapy (IMRT) with and without selective sparing (SPA) of contralateral hippocampus, neural stem cell compartment (NSC) and limbic circuit. We prepared four PBRT treatment plans for four patients with high-grade gliomas (60Gy in 30 fractions delivered to planning treatment volume (PTV60Gy)). For all plans, a structure denoted 'uninvolved brain' was created, which included all brain tissue not part of PTV or standard (STD) organs at risk (OAR). No dosimetric constraints were included for uninvolved brain. Selective SPA plans were prepared with IMRT and HT; contralateral hippocampus, NSC and limbic circuit were contoured; and dosimetric constraints were entered for these structures without compromising dose to PTV or STD OAR. We compared V100 and D95 for PTV46Gy and PTV60Gy, and ID brain for all plans. There were no significant differences in V100 and D95 for PTV46Gy and PTV60Gy. ID brain was lower in traditional IMRT versus HT plans for STD and SPA plans (mean ID brain 23.64Gy vs. 28Gy and 18.7Gy vs. 24.5Gy, respectively) and in SPA versus STD plans both with IMRT and HT (18.7Gy vs. 23.64Gy and 24.5Gy vs. 28Gy, respectively). n the setting of PBRT for high-grade gliomas, IMRT reduces ID brain compared with HT with or without selective SPA of contralateral hippocampus, limbic circuit and NSC, and the use of selective SPA reduces ID brain compared with STD PBRT delivered with either traditional IMRT or HT.

  15. Introduction to the m = 1 helicity source

    International Nuclear Information System (INIS)

    Platts, D.A.; Jarboe, T.R.; Wright, B.L.

    1985-01-01

    The m = 1 Helicity Source, formerly called the Kinked Z-pinch, was developed as part of the Electrode Studies program at Los Alamos. The Electrode Studies program was initiated to study the control of electrode erosion in long discharge duration spheromak sources. Erosion control is necessary to reduce plasma impurities and to obtain adequate electrode lifetimes. The first task of the Electrode Studies program is to determine, from among a variety of configurations including the coaxial one, a helicity source geometry with good prospects for erosion control. The more efficient the helicity source the easier it will be to control erosion, but the source most also be easy to diagnose and modify if it is to be a useful test bed. The various erosion control techniques which have been proposed will require extensive experimentation to evaluate and optimize. Proposed techniques include, using refractory metals, profiling of the electrodes and magnetic fields, and various gas injection schemes including porous electrodes. It is considered necessary to do these experiments on an optimized helicity source so that the electrode geometries and plasma properties will be relevant. Therefore the present Electrode Studies program is aimed at developing an improved helicity source design

  16. Clinical application of helical CT colonography

    International Nuclear Information System (INIS)

    Zeng Huiliang; Zhu Xinjin; Liang Rujian; Liang Jianhao; Ou Weiqian; Wen Haomao

    2009-01-01

    Objective: To investigate the clinical value of 16-slice helical CT colonography in the diagnosis of colon tumor and polypus. Methods: 16-slice helical CT volumetric scanning was performed in 18 patients with colonic disease, including colonic tumor (n=16) and colonic polypus (n=2). 3D images, virtual endoscopy and multiplanar reformation were obtained in the AW4.1 workstation. CT appearances were compared with operation and fiberoptic colonoscopy. Results: Satisfied results were achieved from 18 patients, no difference found in results between CT colonography and operation in 16 patients with colonic tumor. Conclusion: 16-slice helical CT colonography is of great value in preoperative staging of colonic tumor and have a high value in clinical application. (authors)

  17. Helicity antenna showers for hadron colliders

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Nadine; Skands, Peter [Monash University, School of Physics and Astronomy, Clayton, VIC (Australia); Lifson, Andrew [Monash University, School of Physics and Astronomy, Clayton, VIC (Australia); ETH Zuerich, Zurich (Switzerland)

    2017-10-15

    We present a complete set of helicity-dependent 2 → 3 antenna functions for QCD initial- and final-state radiation. The functions are implemented in the Vincia shower Monte Carlo framework and are used to generate showers for hadron-collider processes in which helicities are explicitly sampled (and conserved) at each step of the evolution. Although not capturing the full effects of spin correlations, the explicit helicity sampling does permit a significantly faster evaluation of fixed-order matrix-element corrections. A further speed increase is achieved via the implementation of a new fast library of analytical MHV amplitudes, while matrix elements from Madgraph are used for non-MHV configurations. A few examples of applications to QCD 2 → 2 processes are given, comparing the newly released Vincia 2.200 to Pythia 8.226. (orig.)

  18. Manipulation of wavefront using helical metamaterials.

    Science.gov (United States)

    Yang, Zhenyu; Wang, Zhaokun; Tao, Huan; Zhao, Ming

    2016-08-08

    Helical metamaterials, a kind of 3-dimensional structure, has relatively strong coupling effect among the helical nano-wires. Therefore, it is expected to be a good candidate for generating phase shift and controlling wavefront with high efficiency. In this paper, using the finite-difference time-domain (FDTD) method, we studied the phase shift properties in the helical metamaterials. It is found that the phase shift occurs for both transmitted and reflected light waves. And the maximum of reflection coefficients can reach over 60%. In addition, the phase shift (φ) is dispersionless in the range of 600 nm to 860 nm, that is, it is only dominated by the initial angle (θ) of the helix. The relationship between them is φ = ± 2θ. Using Jones calculus we give a further explanation for these properties. Finally, by arranging the helixes in an array with a constant phase gradient, the phenomenon of anomalous refraction was also observed in a broad wavelength range.

  19. Helicity antenna showers for hadron colliders

    Science.gov (United States)

    Fischer, Nadine; Lifson, Andrew; Skands, Peter

    2017-10-01

    We present a complete set of helicity-dependent 2→ 3 antenna functions for QCD initial- and final-state radiation. The functions are implemented in the Vincia shower Monte Carlo framework and are used to generate showers for hadron-collider processes in which helicities are explicitly sampled (and conserved) at each step of the evolution. Although not capturing the full effects of spin correlations, the explicit helicity sampling does permit a significantly faster evaluation of fixed-order matrix-element corrections. A further speed increase is achieved via the implementation of a new fast library of analytical MHV amplitudes, while matrix elements from Madgraph are used for non-MHV configurations. A few examples of applications to QCD 2→ 2 processes are given, comparing the newly released Vincia 2.200 to Pythia 8.226.

  20. Neutrino's helicity in a gravitational field

    International Nuclear Information System (INIS)

    Pansart, J.P.

    1996-01-01

    By using approximated solutions of Dirac's equation, we show that there is no helicity reversal for light neutrinos in the Schwarzschild metric nor in an expanding universe. The actual coupling between a particle spin and the angular momentum of a heavy rotating body induces a possible helicity reversal but with an unobservable probability proportional to m 2 p / E 2 , where m p is the particle mass and E its energy. In these calculations, the helicity is defined through the spin orientation with respect to the current and not with respect to the linear momentum. This definition gives simple expressions and is equal to the usual definition in the case of a flat space. (N.T.)

  1. Single-superfield helical-phase inflation

    Energy Technology Data Exchange (ETDEWEB)

    Ketov, Sergei V., E-mail: ketov@tmu.ac.jp [Department of Physics, Tokyo Metropolitan University, Minami-ohsawa 1-1, Hachioji-shi, Tokyo 192-0397 (Japan); Kavli Institute for the Physics and Mathematics of the Universe (IPMU), The University of Tokyo, Chiba 277-8568 (Japan); Institute of Physics and Technology, Tomsk Polytechnic University, 30 Lenin Ave., Tomsk 634050 (Russian Federation); Terada, Takahiro, E-mail: takahiro@hep-th.phys.s.u-tokyo.ac.jp [Department of Physics, The University of Tokyo, Tokyo 113-0033 (Japan); Deutsches Elektronen-Synchrotron (DESY), 22607 Hamburg (Germany)

    2016-01-10

    Large-field inflation in supergravity requires the approximate global symmetry needed to protect flatness of the scalar potential. In helical-phase inflation, the U(1) symmetry of the Kähler potential is assumed, the phase part of the complex scalar of a chiral superfield plays the role of inflaton, and the radial part is strongly stabilized. The original model of helical phase inflation, proposed by Li, Li and Nanopoulos (LLN), employs an extra (stabilizer) superfield. We propose a more economical new class of the helical phase inflationary models without a stabilizer superfield. As the specific examples, the quadratic, the natural, and the Starobinsky-type inflationary models are studied in our approach.

  2. Resonant helical fields in the TBR tokamak

    International Nuclear Information System (INIS)

    Bender, O.W.

    1986-01-01

    The influence of external resonant helical fields (RHF) in the tokamak TBR plasma discharges was investigated. These fields were created by helical windings wounded on the TBR vessel with the same helicity of rational magnetic surfaces, producing resonant efects on these surfaces. The characteristics of the MHZ activity (amplitude, frequency and poloidal and toroidal wave numbers, m=2,3,4 and n=1, respectively) during the plasma discharges were modified by eletrical winding currents of the order of 2% of the plasma current. These characterisitics were measured for diferent discharges safety factors at the limiter (q) between 3 and 4, with and without the RHF, with the atenuation of the oscillation amplitudes and the increasing of their frequencies. The existente of expontaneous and induced magnetic islands were investigated. The data were compared with results obtained in other tokamaks. (author) [pt

  3. The helical structure of DNA facilitates binding

    International Nuclear Information System (INIS)

    Berg, Otto G; Mahmutovic, Anel; Marklund, Emil; Elf, Johan

    2016-01-01

    The helical structure of DNA imposes constraints on the rate of diffusion-limited protein binding. Here we solve the reaction–diffusion equations for DNA-like geometries and extend with simulations when necessary. We find that the helical structure can make binding to the DNA more than twice as fast compared to a case where DNA would be reactive only along one side. We also find that this rate advantage remains when the contributions from steric constraints and rotational diffusion of the DNA-binding protein are included. Furthermore, we find that the association rate is insensitive to changes in the steric constraints on the DNA in the helix geometry, while it is much more dependent on the steric constraints on the DNA-binding protein. We conclude that the helical structure of DNA facilitates the nonspecific binding of transcription factors and structural DNA-binding proteins in general. (paper)

  4. Turbulent Helicity in the Atmospheric Boundary Layer

    Science.gov (United States)

    Chkhetiani, Otto G.; Kurgansky, Michael V.; Vazaeva, Natalia V.

    2018-05-01

    We consider the assumption postulated by Deusebio and Lindborg (J Fluid Mech 755:654-671, 2014) that the helicity injected into the Ekman boundary layer undergoes a cascade, with preservation of its sign (right- or alternatively left-handedness), which is a signature of the system rotation, from large to small scales, down to the Kolmogorov microscale of turbulence. At the same time, recent direct field measurements of turbulent helicity in the steppe region of southern Russia near Tsimlyansk Reservoir show the opposite sign of helicity from that expected. A possible explanation for this phenomenon may be the joint action of different scales of atmospheric flows within the boundary layer, including the sea-breeze circulation over the test site. In this regard, we consider a superposition of the classic Ekman spiral solution and Prandtl's jet-like slope-wind profile to describe the planetary boundary-layer wind structure. The latter solution mimics a hydrostatic shallow breeze circulation over a non-uniformly heated surface. A 180°-wide sector on the hodograph plane exists, within which the relative orientation of the Ekman and Prandtl velocity profiles favours the left rotation with height of the resulting wind velocity vector in the lowermost part of the boundary layer. This explains the negative (left-handed) helicity cascade toward small-scale turbulent motions, which agrees with the direct field measurements of turbulent helicity in Tsimlyansk. A simple turbulent relaxation model is proposed that explains the measured positive values of the relatively minor contribution to turbulent helicity from the vertical components of velocity and vorticity.

  5. Computational Prediction of Atomic Structures of Helical Membrane Proteins Aided by EM Maps

    Science.gov (United States)

    Kovacs, Julio A.; Yeager, Mark; Abagyan, Ruben

    2007-01-01

    Integral membrane proteins pose a major challenge for protein-structure prediction because only ≈100 high-resolution structures are available currently, thereby impeding the development of rules or empirical potentials to predict the packing of transmembrane α-helices. However, when an intermediate-resolution electron microscopy (EM) map is available, it can be used to provide restraints which, in combination with a suitable computational protocol, make structure prediction feasible. In this work we present such a protocol, which proceeds in three stages: 1), generation of an ensemble of α-helices by flexible fitting into each of the density rods in the low-resolution EM map, spanning a range of rotational angles around the main helical axes and translational shifts along the density rods; 2), fast optimization of side chains and scoring of the resulting conformations; and 3), refinement of the lowest-scoring conformations with internal coordinate mechanics, by optimizing the van der Waals, electrostatics, hydrogen bonding, torsional, and solvation energy contributions. In addition, our method implements a penalty term through a so-called tethering map, derived from the EM map, which restrains the positions of the α-helices. The protocol was validated on three test cases: GpA, KcsA, and MscL. PMID:17496035

  6. Nonideal, helical, vortical magnetohydrodynamic steady states

    International Nuclear Information System (INIS)

    Agim, Y.Z.; Montgomery, D.

    1991-01-01

    The helically-deformed profiles of driven, dissipative magnetohydrodynamic equilibria are constructed through second order in helical amplitude. The resultant plasma configurations are presented in terms of contour plots of magnetic flux function, pressure, current flux function and the mass flux function, along with the stability boundary at which they are expected to appear. For the Wisconsin Phaedrus-T Tokamak, plasma profiles with significant m = 3, n = 1 perturbation seem feasible; for these, the plasma pressure peaks off-axis. For the smaller aspect ratio case, the configuration with m 1,n =1 is thought to be relevant to the density perturbation observed in JET after a pellet injection. (author)

  7. Equilibrium calculations for helical axis stellarators

    International Nuclear Information System (INIS)

    Hender, T.C.; Carreras, B.A.

    1984-04-01

    An average method based on a vacuum flux coordinate system is presented. This average method permits the study of helical axis stellarators with toroidally dominated shifts. An ordering is introduced, and to lowest order the toroidally averaged equilibrium equations are reduced to a Grad-Shafranov equation. Also, to lowest order, a Poisson-type equation is obtained for the toroidally varying corrections to the equilibium. By including these corrections, systems that are toroidally dominated, but with significant helical distortion to the equilibrium, may be studied. Numerical solutions of the average method equations are shown to agree well with three-dimensional calculations

  8. Helical post stellarator. Part 1: Vacuum configuration

    International Nuclear Information System (INIS)

    Moroz, P.E.

    1997-08-01

    Results on a novel type of stellarator configuration, the Helical Post Stellarator (HPS), are presented. This configuration is different significantly from all previously known stellarators due to its unique geometrical characteristics and unique physical properties. Among those are: the magnetic field has only one toroidal period (M = 1), the plasma has an extremely low aspect ratio, A ∼ 1, and the variation of the magnetic field, B, along field lines features a helical ripple on the inside of the torus. Among the main advantages of a HPS for a fusion program are extremely compact, modular, and simple design compatible with significant rotational transform, large plasma volume, and improved particle transport characteristics

  9. Equilibrium studies of helical axis stellarators

    International Nuclear Information System (INIS)

    Hender, T.C.; Carreras, B.A.; Garcia, L.; Harris, J.H.; Rome, J.A.; Cantrell, J.L.; Lynch, V.E.

    1984-01-01

    The equilibrium properties of helical axis stellarators are studied with a 3-D equilibrium code and with an average method (2-D). The helical axis ATF is shown to have a toroidally dominated equilibrium shift and good equilibria up to at least 10% peak beta. Low aspect ratio heliacs, with relatively large toroidal shifts, are shown to have low equilibrium beta limits (approx. 5%). Increasing the aspect ratio and number of field periods proportionally is found to improve the equilibrium beta limit. Alternatively, increasing the number of field periods at fixed aspect ratio which raises and lowers the toroidal shift improves the equilibrium beta limit

  10. Conversion from mutual helicity to self-helicity observed with IRIS

    Science.gov (United States)

    Li, L. P.; Peter, H.; Chen, F.; Zhang, J.

    2014-10-01

    Context. In the upper atmosphere of the Sun observations show convincing evidence for crossing and twisted structures, which are interpreted as mutual helicity and self-helicity. Aims: We use observations with the new Interface Region Imaging Spectrograph (IRIS) to show the conversion of mutual helicity into self-helicity in coronal structures on the Sun. Methods: Using far UV spectra and slit-jaw images from IRIS and coronal images and magnetograms from SDO, we investigated the evolution of two crossing loops in an active region, in particular, the properties of the Si IV line profile in cool loops. Results: In the early stage two cool loops cross each other and accordingly have mutual helicity. The Doppler shifts in the loops indicate that they wind around each other. As a consequence, near the crossing point of the loops (interchange) reconnection sets in, which heats the plasma. This is consistent with the observed increase of the line width and of the appearance of the loops at higher temperatures. After this interaction, the two new loops run in parallel, and in one of them shows a clear spectral tilt of the Si IV line profile. This is indicative of a helical (twisting) motion, which is the same as to say that the loop has self-helicity. Conclusions: The high spatial and spectral resolution of IRIS allowed us to see the conversion of mutual helicity to self-helicity in the (interchange) reconnection of two loops. This is observational evidence for earlier theoretical speculations. Movie associated with Fig. 1 and Appendix A are available in electronic form at http://www.aanda.org

  11. Is rule of halves still an occurrence in South India: Findings from community-based survey in a selected urban area of Puducherry

    Directory of Open Access Journals (Sweden)

    S S Kar

    2017-01-01

    Full Text Available Background: The objective of the present study was to assess the applicability of the rule of halves in an urban population of Puducherry, South India. We also aimed to find the correlates associated with undiagnosed hypertension to facilitate targeted screening. Methodology: We derive our observation from a community-based cross-sectional study conducted using the World Health Organization STEPwise approach to surveillance in urban slum of Puducherry during 2014–15. Blood pressure (BP was measured for all the study subjects (n = 2399, and the subjects were classified as hypertensive using Joint National Committee 8 criteria, systolic BP (SBP ≥140 mm Hg and/or diastolic BP (DBP ≥90 mmHg and/or known hypertensives and/or treatment with antihypertensive drugs. Controlled hypertension was defined as SBP <140 mmHg and DBP <90 mmHg. Results: Of 2399, 799 (33.3%; 95% confidence interval [CI]: 31.4%–35.2% adults were found to have raised BP by any means (known and unknown hypertensives. Of the 799, 367 (15.3%; 95%CI: 13.9%–16.8% of study participants were known hypertensives. Of the known hypertensives, 74.7% (274/367 were put on treatment (drugs and or lifestyle modification, and 80% (218/274 were on regular treatment. Higher proportions of men were found to have undiagnosed hypertension compared to women (26.1 vs. 19.8%, P < 0.001. Similarly, adult from below poverty line (23.8 vs. 20%, P < 0.001, unskilled laborer (26.6 vs. 20%, P < 0.001, and literacy less than middle school (12.3 vs. 23%, P < 0.001 had more undiagnosed hypertension. Conclusion: In the selected urban area of Puducherry around one-third of the adult populations are having hypertension, including the 54% of undiagnosed hypertension. Adults from the vulnerable subgroups such as lower level of literacy, below poverty line, and unskilled work are found to have higher proportions of undiagnosed hypertension.

  12. Early clinical phase of patient's management after polytrauma using 1- and 4-slice helical CT

    International Nuclear Information System (INIS)

    Kloeppel, R.; Kahn, T.; Schreiter, D.; Dietrich, J.; Josten, C.

    2002-01-01

    In the early clinical phase the comprehensive imaging of patients with multiple trauma using helical CT is already established. Aim of this study was to assess whether MSCT may improve the patient management and the diagnostic results.The procedure is designed as follows: after life-thretening treatment x-ray of chest and ultrasound are carried out in the emergency room. Then the patient is moved to CT. From 1998 to december 2000 241 patients were examined using a single slice helical CT (Somatom plus 4), in 2001 79 patients using a 4-slice helical CT (Somatom VZ, Siemens Med.Sol.). After CT selected radiograms of the extremities were taken.359 of 360 procedures were carried out successfully. Excluding 1 case (death during 1-sl. h CT) all relevant lesions of head, neck, and body were diagnosed. Although the patients had an injury severity score of ∼30. The change from 1slice-helical CT to 4 slice-helical CT allowed us to reduce the stay in the CT room from 28 to 16 min. The total lethality decreased by ∼4%.Advantages for the patient arose from the standardized examination protocol using multislice CT. If integrated in an interdisciplinary management concept, it is a good compromise between examination time, comprehensive diagnostic imaging, life-saving therapeutic procedures, and therapy planning. (orig.) [de

  13. Dynamics and deformability of α-, 310- and π-helices

    Directory of Open Access Journals (Sweden)

    Narwani Tarun Jairaj

    2018-01-01

    Full Text Available Protein structures are often represented as seen in crystals as (i rigid macromolecules (ii with helices, sheets and coils. However, both definitions are partial because (i proteins are highly dynamic macromolecules and (ii the description of protein structures could be more precise. With regard to these two points, we analyzed and quantified the stability of helices by considering α-helices as well as 310- and π-helices. Molecular dynamic (MD simulations were performed on a large set of 169 representative protein domains. The local protein conformations were followed during each simulation and analyzed. The classical flexibility index (B-factor was confronted with the MD root mean square flexibility (RMSF index. Helical regions were classified according to their level of helicity from high to none. For the first time, a precise quantification showed the percentage of rigid and flexible helices that underlie unexpected behaviors. Only 76.4% of the residues associated with α-helices retain the conformation, while this tendency drops to 40.5% for 310-helices and is never observed for π-helices. α-helix residues that do not remain as an α-helix have a higher tendency to assume β-turn conformations than 310- or π-helices. The 310-helices that switch to the α-helix conformation have a higher B-factor and RMSF values than the average 310-helix but are associated with a lower accessibility. Rare π-helices assume a β-turn, bend and coil conformations, but not α- or 310-helices. The view on π-helices drastically changes with the new DSSP (Dictionary of Secondary Structure of Proteins assignment approach, leading to behavior similar to 310-helices, thus underlining the importance of secondary structure assignment methods.

  14. Review of the helicity formalism; Revision del formalismo de helicidad

    Energy Technology Data Exchange (ETDEWEB)

    Barreiro, F; Cerrada, M; Fernandez, E

    1972-07-01

    Our purpose in these notes has been to present a brief and general review of the helicity formalism. We begin by discussing Lorentz invariance, spin and helicity ideas, in section 1 . In section 2 we deal with the construction of relativistic states and scattering amplitudes in the helicity basis and we study their transformation properties under discrete symmetries. Finally we present some more sophisticated topics like kinematical singularities of helicity amplitudes, kinematical constraints and crossing relations 3, 4, 5 respectively. (Author) 8 refs.

  15. Exabyte helical scan devices at Fermilab

    International Nuclear Information System (INIS)

    Constanta-Fanourakis, P.; Kaczar, K.; Oleynik, G.; Petravick, D.; Votava, M.; White, V.; Hockney, G.; Bracker, S.; de Miranda, J.M.

    1989-05-01

    Exabyte 8mm helical scan storage devices are in use at Fermilab in a number of applications. These devices have the functionality of magnetic tape, but use media which is much more economical and much more dense than conventional 9 track tape. 6 refs., 3 figs

  16. Helical axial injection concept for cyclotrons

    Energy Technology Data Exchange (ETDEWEB)

    Hudson, E.D.

    1981-01-01

    A concept for an external beam injection system using a helical beam path centered on the cyclotron axis is described. This system could be used to couple two accelerator stages, with or without intermediate stripping, in cases where conventional axial injection or radial injection are not practical.

  17. Helical axial injection concept for cyclotrons

    International Nuclear Information System (INIS)

    Hudson, E.D.

    1981-01-01

    A concept for an external beam injection system using a helical beam path centered on the cyclotron axis is described. This system could be used to couple two accelerator stages, with or without intermediate stripping, in cases where conventional axial injection or radial injection are not practical

  18. Electron image reconstruction of helical protein assemblies

    International Nuclear Information System (INIS)

    Cremers, A.F.M.

    1980-01-01

    The analysis of projections of large ordered biological systems obtained by electron microscopy of negatively stained specimens is described. The biological structures amenable to this approach are constructed from a large number of identical protein molecules, which are arranged according to helical symmetry. Electron images of these structures generally contain sufficient information in order to calculate a three-dimensional density map. (Auth.)

  19. Adaptive radiotherapy using helical tomotherapy system

    International Nuclear Information System (INIS)

    Jeswani, Sam; Ruchala, Kenneth; Olivera, Gustavo; Mackie, T.R.

    2008-01-01

    As commonly known in the field, adaptive radiation therapy (ART) is the use of feedback to modify a radiotherapy treatment. There are numerous ways in which this feedback can be received and used, and this presentation will discuss some of the implementations of ART being investigated with a helical TomoTherapy system

  20. Topological characteristics of helical repeat proteins

    NARCIS (Netherlands)

    Groves, M R; Barford, D

    The recent elucidation of protein structures based upon repeating amino acid motifs, including the armadillo motif, the HEAT motif and tetratricopeptide repeats, reveals that they belong to the class of helical repeat proteins. These proteins share the common property of being assembled from tandem

  1. A Prospective Evaluation of Helical Tomotherapy

    International Nuclear Information System (INIS)

    Bauman, Glenn; Yartsev, Slav; Rodrigues, George; Lewis, Craig; Venkatesan, Varagur M.; Yu, Edward; Hammond, Alex; Perera, Francisco; Ash, Robert; Dar, A. Rashid; Lock, Michael; Baily, Laura; Coad, Terry C; Trenka, Kris C.; Warr, Barbara; Kron, Tomas; Battista, Jerry; Van Dyk, Jake

    2007-01-01

    Purpose: To report results from two clinical trials evaluating helical tomotherapy (HT). Methods and Materials: Patients were enrolled in one of two prospective trials of HT (one for palliative and one for radical treatment). Both an HT plan and a companion three-dimensional conformal radiotherapy (3D-CRT) plan were generated. Pretreatment megavoltage computed tomography was used for daily image guidance. Results: From September 2004 to January 2006, a total of 61 sites in 60 patients were treated. In all but one case, a clinically acceptable tomotherapy plan for treatment was generated. Helical tomotherapy plans were subjectively equivalent or superior to 3D-CRT in 95% of plans. Helical tomotherapy was deemed equivalent or superior in two thirds of dose-volume point comparisons. In cases of inferiority, differences were either clinically insignificant and/or reflected deliberate tradeoffs to optimize the HT plan. Overall imaging and treatment time (median) was 27 min (range, 16-91 min). According to a patient questionnaire, 78% of patients were satisfied to very satisfied with the treatment process. Conclusions: Helical tomotherapy demonstrated clear advantages over conventional 3D-CRT in this diverse patient group. The prospective trials were helpful in deploying this technology in a busy clinical setting

  2. Helicity-flip in particle production on nuclei

    International Nuclear Information System (INIS)

    Faeldt, G.

    1977-01-01

    Coherent nuclear production processes are generally analyzed assuming helicity conserving production amplitudes. In view of the uncertainties of the actual helicity structure this could be a dangerous assumption. It is shown that helicity-flip contributions might be part of the explanation of the small effective (pππ)-nucleon cross sections observed in coherent production. (Auth.)

  3. Age Discrimination and the FAA Age 60 Rule. Hearing before the Select Committee on Aging. House of Representatives, Ninety-Ninth Congress, First Session.

    Science.gov (United States)

    Congress of the U.S., Washington, DC. House Select Committee on Aging.

    This document presents witness testimonies and related materials from a Congressional hearing called to examine the mandatory retirement age of 60 for airline pilots. In opening remarks, Congressmen Roybal and Pepper question this ruling, citing productivity of older workers and the lack of data to support any specific age for mandatory…

  4. Comparative analysis of conceptions of human rights, democracy and the rule of law in selected third countries, FRAME Deliverable 3.3

    NARCIS (Netherlands)

    Sosa, L.P.A.; Timmer, A.S.H.

    2015-01-01

    This report presents a comparative analysis of the different understandings and perspectives on human rights, democracy and rule of law in third countries with which EU has established strategic partnerships: China, India, Peru and South Africa. This explorative report focuses on theoretical

  5. Modeling and Cognitive Behavior: The Effects of Modeling, Modes of Modeling and Selected Model Attributes on Rule-Governed Language Behavior.

    Science.gov (United States)

    Grieshop, James Ivo

    The effect of modeling on the performance of rule-governed language behaviors of 208 male and female, Anglo and Chicano, sixth grade students in Albuquerque, N.M. was experimentally investigated. Eight boys and 8 girls (4 each Chicano and Anglo) were randomly assigned to each of the 12 experimental conditions and to the control group. Three modes…

  6. A real-scale helical coil winding trial of the Large Helical Device

    International Nuclear Information System (INIS)

    Senba, T.; Yamamoto, T.; Tamaki, T.; Asano, K.; Suzuki, S.; Yamauchi, T.; Uchida, K.; Nakanishi, K.; Yamagiwa, T.; Suzuki, S.; Miyoshi, R.; Sasa, H.; Watanabe, S.; Tatemura, M.; Hatada, N.; Yamaguchi, S.; Imagawa, S.; Yanagi, N.; Satow, T.; Yamamoto, J.; Motojima, O.

    1995-01-01

    A real-scale helical coil winding trial of the Large Helical Device (LHD) has been conducted for a study of coil winding configuration and winding methods and for exhibiting the state of the art. It includes construction and test run of a specifically designed winding machine and development of various manufacturing methods for accurate coil winding. It has been carried out in Hitachi Works before in situ winding, and has provided much needed engineering data for construction of the LHD. (orig.)

  7. Bearing capacity of helical pile foundation in peat soil from different, diameter and spacing of helical plates

    Science.gov (United States)

    Fatnanta, F.; Satibi, S.; Muhardi

    2018-03-01

    In an area dominated by thick peat soil layers, driven piles foundation is often used. These piles are generally skin friction piles where the pile tips do not reach hard stratum. Since the bearing capacity of the piles rely on the resistance of their smooth skin, the bearing capacity of the piles are generally low. One way to increase the bearing capacity of the piles is by installing helical plates around the pile tips. Many research has been performed on helical pile foundation. However, literature on the use of helical pile foundation on peat soil is still hardly found. This research focus on the study of axial bearing capacity of helical pile foundation in peat soil, especially in Riau Province. These full-scale tests on helical pile foundation were performed in a rectangular box partially embedded into the ground. The box is filled with peat soil, which was taken from Rimbo Panjang area in the district of Kampar, Riau Province. Several helical piles with different number, diameter and spacing of the helical plates have been tested and analysed. The tests result show that helical pile with three helical plates of uniform diameter has better bearing capacity compared to other helical piles with varying diameter and different number of helical plates. The bearing capacity of helical pile foundation is affected by the spacing between helical plates. It is found that the effective helical plates spacing for helical pile foundation with diameter of 15cm to 35cm is between 20cm to 30cm. This behaviour may be considered to apply to other type of helical pile foundations in peat soil.

  8. Pyrolysis of Helical Coordination Polymers for Metal-Sulfide-Based Helices with Broadband Chiroptical Activity.

    Science.gov (United States)

    Hirai, Kenji; Yeom, Bongjun; Sada, Kazuki

    2017-06-27

    Fabrication of chiroptical materials with broadband response in the visible light region is vital to fully realize their potential applications. One way to achieve broadband chiroptical activity is to fabricate chiral nanostructures from materials that exhibit broadband absorption in the visible light region. However, the compounds used for chiroptical materials have predominantly been limited to materials with narrowband spectral response. Here, we synthesize Ag 2 S-based nanohelices derived from helical coordination polymers. The right- and left-handed coordination helices used as precursors are prepared from l- and d-glutathione with Ag + and a small amount of Cu 2+ . The pyrolysis of the coordination helices yields right- and left-handed helices of Cu 0.12 Ag 1.94 S/C, which exhibit chiroptical activity spanning the entire visible light region. Finite element method simulations substantiate that the broadband chiroptical activity is attributed to synergistic broadband light absorption and light scattering. Furthermore, another series of Cu 0.10 Ag 1.90 S/C nanohelices are synthesized by choosing the l- or d-Glu-Cys as starting materials. The pitch length of nanohelicies is controlled by changing the peptides, which alters their chiroptical properties. The pyrolysis of coordination helices enables one to fabricate helical Ag 2 S-based materials that enable broadband chiroptical activity but have not been explored owing to the lack of synthetic routes.

  9. Helical tomotherapy. Experiences of the first 150 patients in Heidelberg

    Energy Technology Data Exchange (ETDEWEB)

    Sterzing, F.; Schubert, K.; Sroka-Perez, G.; Kalz, J.; Debus, J.; Herfarth, K. [Dept. of Radiation Oncology, Univ. of Heidelberg (Germany)

    2008-01-15

    Background and purpose: helical tomotherapy was introduced into clinical routine at the Department of Radiation Oncology, University Hospital of Heidelberg, Germany, in July 2006. This report is intended to describe the experience with the first 150 patients treated with helical tomotherapy. Patient selection, time effort, handling of daily image guidance with megavoltage (MV) CT, and quality of radiation plans shall be assessed. Patients and methods: between July 2006 and May 2007, 150 patients were treated with helical tomotherapy in the University Hospital of Heidelberg. Mean age was 60 years with a minimum of 30 years and a maximum of 85 years. 79 of these patients received radiotherapy as a part of multimodal treatment pre- or postoperatively, 17 patients received treatment as a combined radiochemotherapy. 76% were treated with curative intent. Radiotherapy sites were central nervous system (n = 7), head and neck (n = 28), thoracic (n = 37), abdominal (n = 58) and skeletal system (n = 20). Most common tumor entities were prostate cancer (n = 28), breast cancer (n = 17), gastrointestinal tumors (n = 19), pharyngeal carcinoma (n = 14), lymphoma (n = 13), metastatic disease (bone n = 14, liver n = 6, lung n = 4, lymph node n = 2), sarcoma (n = 8), malignant pleural mesothelioma (n = 5), ovarian cancer treated with whole abdominal irradiation (n = 4), lung cancer (n = 3), skin malignancies (n = 3), chordoma (n = 2), meningioma (n = 2), one ependymoma and one medulloblastoma treated with craniospinal axis irradiation (n = 2), and others (n = 4). Nine patients were treated with single-fraction radiosurgery, nine with image-guided spinal reirradiation, and twelve patients were treated at multiple targets simultaneously. A pretreatment MV-CT scan was performed in 98.2% of the 3,026 fractions applied. After matching with the kilovoltage planning CT, corrections for translations and rotation around longitudinal axis (roll) were done. Results: mean time on table was 24

  10. Dosimetric verification of helical tomotherapy for total scalp irradiation

    International Nuclear Information System (INIS)

    Hardcastle, Nicholas; Soisson, Emilie; Metcalfe, Peter; Rosenfeld, Anatoly B.; Tome, Wolfgang A.

    2008-01-01

    Total scalp irradiation is a treatment technique used for a variety of superficial malignancies. Helical tomotherapy is an effective technique used for total scalp irradiation. Recent published work has shown the TomoTherapy planning system to overestimate the superficial dose. In this study, the superficial doses for a helical tomotherapy total scalp irradiation have been measured on an anthropomorphic phantom using radiochromic and radiographic film as well as a new skin dosimeter, the MOSkin. The superficial dose was found to be accurately calculated by the TomoTherapy planning system. This is in contrast to recent reports, probably due to a combination of the smaller dose grid resolution used in planning and this particular treatment primarily consisting of beamlets tangential to the scalp. The superficial dose was found to increase from 33.6 to 41.2 Gy and 36.0 to 42.0 Gy over the first 2 mm depth in the phantom in selected regions of the PTV, measured with radiochromic film. The prescription dose was 40 Gy. The superficial dose was at the prescription dose or higher in some regions due to the bolus effect of the thermoplastic head mask and the head rest used to aid treatment setup. It is suggested that to achieve the prescription dose at the surface (≤2 mm depth) bolus or a custom thermoplastic helmet is used.

  11. Ion temperature gradient modes in toroidal helical systems

    Energy Technology Data Exchange (ETDEWEB)

    Kuroda, T. [Graduate University for Advanced Studies, Toki, Gifu (Japan); Sugama, H.; Kanno, R.; Okamoto, M.

    2000-04-01

    Linear properties of ion temperature gradient (ITG) modes in helical systems are studied. The real frequency, growth rate, and eigenfunction are obtained for both stable and unstable cases by solving a kinetic integral equation with proper analytic continuation performed in the complex frequency plane. Based on the model magnetic configuration for toroidal helical systems like the Large Helical Device (LHD), dependences of the ITG mode properties on various plasma equilibrium parameters are investigated. Particularly, relative effects of {nabla}B-curvature drifts driven by the toroidicity and by the helical ripples are examined in order to compare the ITG modes in helical systems with those in tokamaks. (author)

  12. Ion temperature gradient modes in toroidal helical systems

    International Nuclear Information System (INIS)

    Kuroda, T.; Sugama, H.; Kanno, R.; Okamoto, M.

    2000-04-01

    Linear properties of ion temperature gradient (ITG) modes in helical systems are studied. The real frequency, growth rate, and eigenfunction are obtained for both stable and unstable cases by solving a kinetic integral equation with proper analytic continuation performed in the complex frequency plane. Based on the model magnetic configuration for toroidal helical systems like the Large Helical Device (LHD), dependences of the ITG mode properties on various plasma equilibrium parameters are investigated. Particularly, relative effects of ∇B-curvature drifts driven by the toroidicity and by the helical ripples are examined in order to compare the ITG modes in helical systems with those in tokamaks. (author)

  13. Biot-Savart helicity versus physical helicity: A topological description of ideal flows

    Science.gov (United States)

    Sahihi, Taliya; Eshraghi, Homayoon

    2014-08-01

    For an isentropic (thus compressible) flow, fluid trajectories are considered as orbits of a family of one parameter, smooth, orientation-preserving, and nonsingular diffeomorphisms on a compact and smooth-boundary domain in the Euclidian 3-space which necessarily preserve a finite measure, later interpreted as the fluid mass. Under such diffeomorphisms the Biot-Savart helicity of the pushforward of a divergence-free and tangent to the boundary vector field is proved to be conserved and since these circumstances present an isentropic flow, the conservation of the "Biot-Savart helicity" is established for such flows. On the other hand, the well known helicity conservation in ideal flows which here we call it "physical helicity" is found to be an independent constant with respect to the Biot-Savart helicity. The difference between these two helicities reflects some topological features of the domain as well as the velocity and vorticity fields which is discussed and is shown for simply connected domains the two helicities coincide. The energy variation of the vorticity field is shown to be formally the same as for the incompressible flow obtained before. For fluid domains consisting of several disjoint solid tori, at each time, the harmonic knot subspace of smooth vector fields on the fluid domain is found to have two independent base sets with a special type of orthogonality between these two bases by which a topological description of the vortex and velocity fields depending on the helicity difference is achieved since this difference is shown to depend only on the harmonic knot parts of velocity, vorticity, and its Biot-Savart vector field. For an ideal magnetohydrodynamics (MHD) flow three independent constant helicities are reviewed while the helicity of magnetic potential is generalized for non-simply connected domains by inserting a special harmonic knot field in the dynamics of the magnetic potential. It is proved that the harmonic knot part of the vorticity

  14. Collaboration rules.

    Science.gov (United States)

    Evans, Philip; Wolf, Bob

    2005-01-01

    Corporate leaders seeking to boost growth, learning, and innovation may find the answer in a surprising place: the Linux open-source software community. Linux is developed by an essentially volunteer, self-organizing community of thousands of programmers. Most leaders would sell their grandmothers for workforces that collaborate as efficiently, frictionlessly, and creatively as the self-styled Linux hackers. But Linux is software, and software is hardly a model for mainstream business. The authors have, nonetheless, found surprising parallels between the anarchistic, caffeinated, hirsute world of Linux hackers and the disciplined, tea-sipping, clean-cut world of Toyota engineering. Specifically, Toyota and Linux operate by rules that blend the self-organizing advantages of markets with the low transaction costs of hierarchies. In place of markets' cash and contracts and hierarchies' authority are rules about how individuals and groups work together (with rigorous discipline); how they communicate (widely and with granularity); and how leaders guide them toward a common goal (through example). Those rules, augmented by simple communication technologies and a lack of legal barriers to sharing information, create rich common knowledge, the ability to organize teams modularly, extraordinary motivation, and high levels of trust, which radically lowers transaction costs. Low transaction costs, in turn, make it profitable for organizations to perform more and smaller transactions--and so increase the pace and flexibility typical of high-performance organizations. Once the system achieves critical mass, it feeds on itself. The larger the system, the more broadly shared the knowledge, language, and work style. The greater individuals' reputational capital, the louder the applause and the stronger the motivation. The success of Linux is evidence of the power of that virtuous circle. Toyota's success is evidence that it is also powerful in conventional companies.

  15. Magnetic helicity balance in the Sustained Spheromak Plasma Experiment

    International Nuclear Information System (INIS)

    Stallard, B.W.; Hooper, E.B.; Woodruff, S.; Bulmer, R.H.; Hill, D.N.; McLean, H.S.; Wood, R.D.

    2003-01-01

    The magnetic helicity balance between the helicity input injected by a magnetized coaxial gun, the rate-of-change in plasma helicity content, and helicity dissipation in electrode sheaths and Ohmic losses have been examined in the Sustained Spheromak Plasma Experiment (SSPX) [E. B. Hooper, L. D. Pearlstein, and R. H. Bulmer, Nucl. Fusion 39, 863 (1999)]. Helicity is treated as a flux function in the mean-field approximation, allowing separation of helicity drive and losses between closed and open field volumes. For nearly sustained spheromak plasmas with low fluctuations, helicity balance analysis implies a decreasing transport of helicity from the gun input into the spheromak core at higher spheromak electron temperature. Long pulse discharges with continuously increasing helicity and larger fluctuations show higher helicity coupling from the edge to the spheromak core. The magnitude of the sheath voltage drop, inferred from cathode heating and a current threshold dependence of the gun voltage, shows that sheath losses are important and reduce the helicity injection efficiency in SSPX

  16. Helical CT of congenital ossicular anomalies

    International Nuclear Information System (INIS)

    Osada, Hisato; Machida, Kikuo; Honda, Norinari

    2001-01-01

    Since January 1996 to December 2000, 26 cases of congenital ossicular anomaly could be diagnosed with helical CT. All cases were unilateral. In 8 patients with malformation of the external ear, CT showed malleoincudal fixation (n=5), malleoincudal fixation and deformed incuts long process (n=1), deformed incus long process (n=1), and partial fusion of malleus neck and incus long process (n=1). In 18 patients with normal external ear, CT showed defect of the incus long process (n=5), defect of both the incus long process and stapes superstructure (n=8, 2 patients with congenital cholesteatoma, 1 with hypoplastic oval window), defect of the stapes superstructure (n=2, 1 patient with oval window absence), defect of the malleus manubrium (n=1), ossification of the stampede's tendon (n=1), and monopod stapes (n=1). Helical CT can evaluate the auditory ossicular chain in detail and is useful for diagnosing congenital ossicular anomaly. (author)

  17. Weaving Knotted Vector Fields with Tunable Helicity.

    Science.gov (United States)

    Kedia, Hridesh; Foster, David; Dennis, Mark R; Irvine, William T M

    2016-12-30

    We present a general construction of divergence-free knotted vector fields from complex scalar fields, whose closed field lines encode many kinds of knots and links, including torus knots, their cables, the figure-8 knot, and its generalizations. As finite-energy physical fields, they represent initial states for fields such as the magnetic field in a plasma, or the vorticity field in a fluid. We give a systematic procedure for calculating the vector potential, starting from complex scalar functions with knotted zero filaments, thus enabling an explicit computation of the helicity of these knotted fields. The construction can be used to generate isolated knotted flux tubes, filled by knots encoded in the lines of the vector field. Lastly, we give examples of manifestly knotted vector fields with vanishing helicity. Our results provide building blocks for analytical models and simulations alike.

  18. Vacuum systems for the ILC helical undulator

    CERN Document Server

    Malyshev, O B; Clarke, J A; Bailey, I R; Dainton, J B; Malysheva, L I; Barber, D P; Cooke, P; Baynham, E; Bradshaw, T; Brummitt, A; Carr, S; Ivanyushenkov, Y; Rochford, J; Moortgat-Pick, G A

    2007-01-01

    The International Linear Collider (ILC) positron source uses a helical undulator to generate polarized photons of ∼10MeV∼10MeV at the first harmonic. Unlike many undulators used in synchrotron radiation sources, the ILC helical undulator vacuum chamber will be bombarded by photons, generated by the undulator, with energies mostly below that of the first harmonic. Achieving the vacuum specification of ∼100nTorr∼100nTorr in a narrow chamber of 4–6mm4–6mm inner diameter, with a long length of 100–200m100–200m, makes the design of the vacuum system challenging. This article describes the vacuum specifications and calculations of the flux and energy of photons irradiating the undulator vacuum chamber and considers possible vacuum system design solutions for two cases: cryogenic and room temperature.

  19. SUPERCONDUCTING HELICAL SNAKE MAGNETS: CONSTRUCTION AND MEASUREMENTS

    International Nuclear Information System (INIS)

    Mackay, W.W.; Anerella, M.; Courant, E.

    1999-01-01

    In order to collide polarized protons, the RHIC project will have two snakes in each ring and four rotators around each of two interaction regions. Two snakes on opposite sides of each ring can minimize depolarization during acceleration by keeping the spin tune at a half. Since the spin direction is normally along the vertical direction in a flat ring, spin rotators must be used around an interaction point to have longitudinal polarization in a collider experiment. Each snake or rotator will be composed of four helical dipoles to provide the required rotation of spin with minimal transverse orbit excursions in a compact length of 10m. The basic helical dipole is a superconducting magnet producing a transverse dipole field which is twisted about the magnet axis through 360 o in a length of 2.4 m. The design and construction of the magnets is described in this paper

  20. Australian road rules

    Science.gov (United States)

    2009-02-01

    *These are national-level rules. Australian Road Rules - 2009 Version, Part 18, Division 1, Rule 300 "Use of Mobile Phones" describes restrictions of mobile phone use while driving. The rule basically states that drivers cannot make or receive calls ...

  1. Buoyant Helical Twin-Axial Wire Antenna

    Science.gov (United States)

    2016-11-15

    February 2017 The below identified patent application is available for licensing. Requests for information should be addressed to...300169 1 of 9 BUOYANT HELICAL TWIN-AXIAL WIRE ANTENNA CROSS REFERENCE TO OTHER PATENT APPLICATIONS [0001] This application is a divisional...application and claims the benefit of the filing date of United States Patent Application No. 14/280,889; filed on May 19, 2014; and entitled “Twin-Axial

  2. Molecular Dynamics with Helical Periodic Boundary Conditions

    Czech Academy of Sciences Publication Activity Database

    Kessler, Jiří; Bouř, Petr

    2014-01-01

    Roč. 35, č. 21 (2014), s. 1552-1559 ISSN 0192-8651 R&D Projects: GA ČR GAP208/11/0105; GA MŠk(CZ) LH11033 Grant - others:GA AV ČR(CZ) M200551205; GA MŠk(CZ) LM2010005 Institutional support: RVO:61388963 Keywords : periodic boundary conditions * helical symmetry * molecular dynamics * protein structure * amyloid fibrils Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.589, year: 2014

  3. Simplification of the helical TEN2 laser

    Science.gov (United States)

    Krahn, K.-H.

    1980-04-01

    The observation that the helical TEN2 laser can effectively be simplified by giving up the use of decoupling elements as well as by abolishing the segmentation of the electrode structure is examined. Although, as a consequence of this simplification, the operating pressure range was slightly decreased, the output power could be improved by roughly 30%, a result which is attributed to the new electrode geometry exhibiting lower inductance and lower damping losses.

  4. Field of a helical Siberian Snake

    Energy Technology Data Exchange (ETDEWEB)

    Luccio, A. [Brookhaven National Lab., Upton, NY (United States)

    1995-02-01

    To preserve the spin polarization of a beam of high energy protons in a circular accelerator, magnets with periodic magnetic field, called Siberian Snakes are being used. Recently, it was proposed to build Siberian Snakes with superconducting helical dipoles. In a helical, or twisted dipole, the magnetic field is perpendicular to the axis of the helix and rotates around it as one proceeds along the magnet. In an engineering study of a 4 Tesla helical snake, the coil geometry is derived, by twisting, from the geometry of a cosine superconducting dipole. While waiting for magnetic measurement data on such a prototype, an analytical expression for the field of the helice is important, to calculate the particle trajectories and the spin precession in the helix. This model will also allow to determine the optical characteristics of the snake, as an insertion in the lattice of the accelerator. In particular, one can calculate the integrated multipoles through the magnet and the equivalent transfer matrix. An expression for the field in the helix body, i.e., excluding the fringe field was given in a classical paper. An alternate expression can be found by elaborating on the treatment of the field of a transverse wiggler obtained under the rather general conditions that the variables are separable. This expression exactly satisfies Maxwell`s div and curl equations for a stationary field, {del} {center_dot} B = 0, {del} x B = 0. This approach is useful in that it will allow one to use much of the work already done on the problem of inserting wigglers and undulators in the lattice of a circular accelerator.

  5. Helical waves in easy-plane antiferromagnets

    Science.gov (United States)

    Semenov, Yuriy G.; Li, Xi-Lai; Xu, Xinyi; Kim, Ki Wook

    2017-12-01

    Effective spin torques can generate the Néel vector oscillations in antiferromagnets (AFMs). Here, it is theoretically shown that these torques applied at one end of a normal AFM strip can excite a helical type of spin wave in the strip whose properties are drastically different from characteristic spin waves. An analysis based on both a Néel vector dynamical equation and the micromagnetic simulation identifies the direction of magnetic anisotropy and the damping factor as the two key parameters determining the dynamics. Helical wave propagation requires the hard axis of the easy-plane AFM to be aligned with the traveling direction, while the damping limits its spatial extent. If the damping is neglected, the calculation leads to a uniform periodic domain wall structure. On the other hand, finite damping decelerates the helical wave rotation around the hard axis, ultimately causing stoppage of its propagation along the strip. With the group velocity staying close to spin-wave velocity at the wave front, the wavelength becomes correspondingly longer away from the excitation point. In a sufficiently short strip, a steady-state oscillation can be established whose frequency is controlled by the waveguide length as well as the excitation energy or torque.

  6. Helical CT in acute lower gastrointestinal bleeding

    International Nuclear Information System (INIS)

    Ernst, Olivier; Leroy, Christophe; Sergent, Geraldine; Bulois, Philippe; Saint-Drenant, Sophie; Paris, Jean-Claude

    2003-01-01

    The purpose of this study was to assess the usefulness of helical CT in depicting the location of acute lower gastrointestinal bleeding. A three-phase helical CT of the abdomen was performed in 24 patients referred for acute lower gastrointestinal bleeding. The diagnosis of the bleeding site was established by CT when there was at least one of the following criteria: spontaneous hyperdensity of the peribowel fat; contrast enhancement of the bowel wall; vascular extravasation of the contrast medium; thickening of the bowel wall; polyp or tumor; or vascular dilation. Diverticula alone were not enough to locate the bleeding site. The results of CT were compared with the diagnosis obtained by colonoscopy, enteroscopy, or surgery. A definite diagnosis was made in 19 patients. The bleeding site was located in the small bowel in 5 patients and the colon in 14 patients. The CT correctly located 4 small bowel hemorrhages and 11 colonic hemorrhages. Diagnosis of the primary lesion responsible for the bleeding was made in 10 patients. Our results suggest that helical CT could be a good diagnostic tool in acute lower gastrointestinal bleeding to help the physician to diagnose the bleeding site. (orig.)

  7. Superconducting Helical Snake Magnet for the AGS

    CERN Document Server

    Willen, Erich; Escallier, John; Ganetis, George; Ghosh, Arup; Gupta, Ramesh C; Harrison, Michael; Jain, Animesh K; Luccio, Alfredo U; MacKay, William W; Marone, Andrew; Muratore, Joseph F; Okamura, Masahiro; Plate, Stephen R; Roser, Thomas; Tsoupas, Nicholaos; Wanderer, Peter

    2005-01-01

    A superconducting helical magnet has been built for polarized proton acceleration in the Brookhaven AGS. This "partial Snake" magnet will help to reduce the loss of polarization of the beam due to machine resonances. It is a 3 T magnet some 1940 mm in magnetic length in which the dipole field rotates with a pitch of 0.2053 degrees/mm for 1154 mm in the center and a pitch of 0.3920 degrees/mm for 393 mm in each end. The coil cross-section is made of two slotted cylinders containing superconductor. In order to minimize residual offsets and deflections of the beam on its orbit through the Snake, a careful balancing of the coil parameters was necessary. In addition to the main helical coils, a solenoid winding was built on the cold bore tube inside the main coils to compensate for the axial component of the field that is experienced by the beam when it is off-axis in this helical magnet. Also, two dipole corrector magnets were placed on the same tube with the solenoid. A low heat leak cryostat was built so that t...

  8. Total scalp irradiation using helical tomotherapy

    International Nuclear Information System (INIS)

    Orton, Nigel; Jaradat, Hazim; Welsh, James; Tome, Wolfgang

    2005-01-01

    Homogeneous irradiation of the scalp poses technical and dosimetric challenges due to the extensive, superficial, curved treatment volume. Conventional treatments on a linear accelerator use multiple matched electron fields or a combination of electron and photon fields. Problems with these techniques include dose heterogeneity in the target due to varying source-to-skin distance (SSD) and angle of beam incidence, significant dose to the brain, and the potential for overdose or underdose at match lines between the fields. Linac-based intensity-modulated radiation therapy (IMRT) plans have similar problems. This work presents treatment plans for total scalp irradiation on a helical tomotherapy machine. Helical tomotherapy is well-suited for scalp irradiation because it has the ability to deliver beamlets that are tangential to the scalp at all points. Helical tomotherapy also avoids problems associated with field matching and use of more than one modality. Tomotherapy treatment plans were generated and are compared to plans for treatment of the same patient on a linac. The resulting tomotherapy plans show more homogeneous target dose and improved critical structure dose when compared to state-of-the-art linac techniques. Target equivalent uniform dose (EUD) for the best tomotherapy plan was slightly higher than for the linac plan, while the volume of brain tissue receiving over 30 Gy was reduced by two thirds. Furthermore, the tomotherapy plan can be more reliably delivered than linac treatments, because the patient is aligned prior to each treatment based on megavoltage computed tomography (MVCT)

  9. Allocating application to group of consecutive processors in fault-tolerant deadlock-free routing path defined by routers obeying same rules for path selection

    Science.gov (United States)

    Leung, Vitus J [Albuquerque, NM; Phillips, Cynthia A [Albuquerque, NM; Bender, Michael A [East Northport, NY; Bunde, David P [Urbana, IL

    2009-07-21

    In a multiple processor computing apparatus, directional routing restrictions and a logical channel construct permit fault tolerant, deadlock-free routing. Processor allocation can be performed by creating a linear ordering of the processors based on routing rules used for routing communications between the processors. The linear ordering can assume a loop configuration, and bin-packing is applied to this loop configuration. The interconnection of the processors can be conceptualized as a generally rectangular 3-dimensional grid, and the MC allocation algorithm is applied with respect to the 3-dimensional grid.

  10. Cryo-EM Structure Determination Using Segmented Helical Image Reconstruction.

    Science.gov (United States)

    Fromm, S A; Sachse, C

    2016-01-01

    Treating helices as single-particle-like segments followed by helical image reconstruction has become the method of choice for high-resolution structure determination of well-ordered helical viruses as well as flexible filaments. In this review, we will illustrate how the combination of latest hardware developments with optimized image processing routines have led to a series of near-atomic resolution structures of helical assemblies. Originally, the treatment of helices as a sequence of segments followed by Fourier-Bessel reconstruction revealed the potential to determine near-atomic resolution structures from helical specimens. In the meantime, real-space image processing of helices in a stack of single particles was developed and enabled the structure determination of specimens that resisted classical Fourier helical reconstruction and also facilitated high-resolution structure determination. Despite the progress in real-space analysis, the combination of Fourier and real-space processing is still commonly used to better estimate the symmetry parameters as the imposition of the correct helical symmetry is essential for high-resolution structure determination. Recent hardware advancement by the introduction of direct electron detectors has significantly enhanced the image quality and together with improved image processing procedures has made segmented helical reconstruction a very productive cryo-EM structure determination method. © 2016 Elsevier Inc. All rights reserved.

  11. Hydrodynamic studies of CNT nanofluids in helical coil heat exchanger

    Science.gov (United States)

    Babita; Sharma, S. K.; Mital Gupta, Shipra; Kumar, Arinjay

    2017-12-01

    Helical coils are extensively used in several industrial processes such as refrigeration systems, chemical reactors, recovery processes etc to accommodate a large heat transfer area within a smaller space. Nanofluids are getting great attention due to their enhanced heat transfer capability. In heat transfer equipments, pressure drop is one of the major factors of consideration for pumping power calculations. So, the present work is aimed to study hydrodynamics of CNT nanofluids in helical coils. In this study, pressure drop characteristics of CNT nanofluid flowing inside horizontal helical coils are investigated experimentally. The helical coil to tube diameter was varied from 11.71 to 27.34 keeping pitch of the helical coil constant. Double distilled water was used as basefluid. SDBS and GA surfactants were added to stablilize CNT nanofluids. The volumetric fraction of CNT nanofluid was varied from 0.003 vol% to 0.051 vol%. From the experimental data, it was analyzed that the friction factor in helical coils is greater than that of straight tubes. Concentration of CNT in nanofluids also has a significant influence on the pressure drop/friction factor of helical coils. At a constant concentration of CNT, decreasing helical coil to tube diameter from 27.24 to 11.71, fanning friction factor of helical coil; f c increases for a constant value of p/d t. This increase in the value of fanning friction factor can be attributed to the secondary flow of CNT nanofluid in helical coils.

  12. Cellular automata with voting rule

    International Nuclear Information System (INIS)

    Makowiec, D.

    1996-01-01

    The chosen local interaction - the voting (majority) rule applied to the square lattice is known to cause the non ergodic cellular automata behaviour. Presented computer simulation results verify two cases of non ergodicity. The first one is implicated by the noise introduced to the local interactions and the second one follows properties of the initial lattice configuration selected at random. For the simplified voting rule - non symmetric voting, the critical behaviour has been explained rigorously. (author)

  13. Helical muon beam cooling channel engineering design

    International Nuclear Information System (INIS)

    Johnson, Rolland

    2015-01-01

    The Helical Cooling Channel (HCC) achieves effective ionization cooling of the six-dimensional (6d) phase space of a muon beam by means of a series of 21st century inventions. In the HCC, hydrogen-pressurized RF cavities enable high RF gradients in strong external magnetic fields. The theory of the HCC, which requires a magnetic field with solenoid, helical dipole, and helical quadrupole components, demonstrates that dispersion in the gaseous hydrogen energy absorber provides effective emittance exchange to enable longitudinal ionization cooling. The 10-year development of a practical implementation of a muon-beam cooling device has involved a series of technical innovations and experiments that imply that an HCC of less than 300 m length can cool the 6d emittance of a muon beam by six orders of magnitude. We describe the design and construction plans for a prototype HCC module based on oxygen-doped hydrogen-pressurized RF cavities that are loaded with dielectric, fed by magnetrons, and operate in a superconducting helical solenoid magnet. The first phase of this project saw the development of a conceptual design for the integration of 805 MHz RF cavities into a 10 T Nb 3 Sn-based HS test section. Two very novel ideas are required to realize the design. The first idea is the use of dielectric inserts in the RF cavities to make them smaller for a given frequency so that the cavities and associated plumbing easily fit inside the magnet cryostat. Calculations indicate that heat loads will be tolerable, while RF breakdown of the dielectric inserts will be suppressed by the pressurized hydrogen gas. The second new idea is the use of a multi-layer Nb 3 Sn helical solenoid. The technology demonstrations for the two aforementioned key components of a 10T, 805 MHz HCC were begun in this project. The work load in the Fermilab Technical Division made it difficult to test a multi-layer Nb 3 Sn solenoid as originally planned. Instead, a complementary project was approved by the

  14. Helical muon beam cooling channel engineering design

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Rolland [Muons, Inc., Batavia, IL (United States)

    2015-08-07

    The Helical Cooling Channel (HCC) achieves effective ionization cooling of the six-dimensional (6d) phase space of a muon beam by means of a series of 21st century inventions. In the HCC, hydrogen-pressurized RF cavities enable high RF gradients in strong external magnetic fields. The theory of the HCC, which requires a magnetic field with solenoid, helical dipole, and helical quadrupole components, demonstrates that dispersion in the gaseous hydrogen energy absorber provides effective emittance exchange to enable longitudinal ionization cooling. The 10-year development of a practical implementation of a muon-beam cooling device has involved a series of technical innovations and experiments that imply that an HCC of less than 300 m length can cool the 6d emittance of a muon beam by six orders of magnitude. We describe the design and construction plans for a prototype HCC module based on oxygen-doped hydrogen-pressurized RF cavities that are loaded with dielectric, fed by magnetrons, and operate in a superconducting helical solenoid magnet. The first phase of this project saw the development of a conceptual design for the integration of 805 MHz RF cavities into a 10 T Nb3Sn-based HS test section. Two very novel ideas are required to realize the design. The first idea is the use of dielectric inserts in the RF cavities to make them smaller for a given frequency so that the cavities and associated plumbing easily fit inside the magnet cryostat. Calculations indicate that heat loads will be tolerable, while RF breakdown of the dielectric inserts will be suppressed by the pressurized hydrogen gas. The second new idea is the use of a multi-layer Nb3Sn helical solenoid. The technology demonstrations for the two aforementioned key components of a 10T, 805 MHz HCC were begun in this project. The work load in the Fermilab Technical Division made it difficult to test a multi-layer Nb3Sn solenoid as originally planned. Instead, a complementary

  15. Single-Sex Schools, Student Achievement, and Course Selection: Evidence from Rule-Based Student Assignments in Trinidad and Tobago. NBER Working Paper No. 16817

    Science.gov (United States)

    Jackson, C. Kirabo

    2011-01-01

    Existing studies on single-sex schooling suffer from biases due to student selection to schools and single-sex schools being better in unmeasured ways. In Trinidad and Tobago students are assigned to secondary schools based on an algorithm allowing one to address self-selection bias and cleanly estimate an upper-bound single-sex school effect. The…

  16. Plasmodium vivax antigen discovery based on alpha-helical coiled coil protein motif.

    Directory of Open Access Journals (Sweden)

    Nora Céspedes

    Full Text Available Protein α-helical coiled coil structures that elicit antibody responses, which block critical functions of medically important microorganisms, represent a means for vaccine development. By using bioinformatics algorithms, a total of 50 antigens with α-helical coiled coil motifs orthologous to Plasmodium falciparum were identified in the P. vivax genome. The peptides identified in silico were chemically synthesized; circular dichroism studies indicated partial or high α-helical content. Antigenicity was evaluated using human sera samples from malaria-endemic areas of Colombia and Papua New Guinea. Eight of these fragments were selected and used to assess immunogenicity in BALB/c mice. ELISA assays indicated strong reactivity of serum samples from individuals residing in malaria-endemic regions and sera of immunized mice, with the α-helical coiled coil structures. In addition, ex vivo production of IFN-γ by murine mononuclear cells confirmed the immunogenicity of these structures and the presence of T-cell epitopes in the peptide sequences. Moreover, sera of mice immunized with four of the eight antigens recognized native proteins on blood-stage P. vivax parasites, and antigenic cross-reactivity with three of the peptides was observed when reacted with both the P. falciparum orthologous fragments and whole parasites. Results here point to the α-helical coiled coil peptides as possible P. vivax malaria vaccine candidates as were observed for P. falciparum. Fragments selected here warrant further study in humans and non-human primate models to assess their protective efficacy as single components or assembled as hybrid linear epitopes.

  17. Systematic periodicity in waviness of vertically aligned carbon nanotubes explained by helical buckling

    Science.gov (United States)

    Jahangiri, Mehdi

    2017-09-01

    A hypothesis is proposed in this work to account for the geometry of individual vertically aligned carbon nanotubes (VACNTs) that not only justifies the directionality of their growth, but also explains the origin of the waviness frequently reported for these nanotube forests. Such waviness has fundamental effects on the transport/conduction properties of VACNTs, either through or along them, regarding phenomena such as mass, stress, heat and electricity. Despite the general opinion about randomness of carbon nanotubes (CNTs) tortuosity, we demonstrate here that rules of helical buckling of tubular strings is applicable to VACNTs, based on which a regular 3D helical geometry is proposed for VACNTs, with a 2D sine wave shape side-profile. In this framework, gradual increase of the total free surface energy by growth of CNTs ensues their partial cohesion, driven by van der Waals interactions, to reduce the excess surface energy. On the other hand, their cohesion is accompanied by their deformation and loss of straightness, which in turn, translates to buildup of an elastic strain energy in the system. The balance of the two energies along with the spatial constraints on each CNT at its contact points with neighboring CNTs, is manifested in its helical buckling, that is systematically influenced by nanostructural characteristics of VACNTs, such as their diameter, wall thickness and inter-CNT spacing.

  18. System assessment of helical reactors in comparison with tokamaks

    International Nuclear Information System (INIS)

    Yamazaki, K.; Imagawa, S.; Muroga, T.; Sagara, A.; Okamura, S.

    2002-10-01

    A comparative assessment of tokamak and helical reactors has been performed using equivalent physics/engineering model and common costing model. Higher-temperature plasma operation is required in tokamak reactors to increase bootstrap current fraction and to reduce current-drive (CD) power. In helical systems, lower-temperature operation is feasible and desirable to reduce helical ripple transport. The capital cost of helical reactor is rather high, however, the cost of electricity (COE) is almost same as that of tokamak reactor because of smaller re-circulation power (no CD power) and less-frequent blanket replacement (lower neutron wall loading). The standard LHD-type helical reactor with 5% beta value is economically equivalent to the standard tokamak with 3% beta. The COE of lower-aspect ratio helical reactor is on the same level of high-β N tokamak reactors. (author)

  19. Ornament Complexity Is Correlated with Sexual Selection: (A Comment on Raia et al., "Cope's Rule and the Universal Scaling Law of Ornament Complexity").

    Science.gov (United States)

    Holman, Luke; Bro-Jørgensen, Jakob

    2016-08-01

    Raia et al. propose that the evolution of the shape and complexity of animal ornaments (e.g., deer antlers) can be explained by interspecific variation in body size and is not influenced by sexual selection. They claim to show that ornament complexity is related to body size by an 0.25-power law and argue that this finding precludes a role for sexual selection in the evolution of ornament complexity. However, their study does not test alternative hypotheses and mismeasures antler shape allometry by omitting much of the published data. We show that an index of sexual selection (sexual size dimorphism) is positively correlated with size-corrected antler complexity and that the allometric slope of complexity is substantially greater than 0.25, contra Raia et al. We conclude that sexual selection and physical constraints both affect the evolution of antler shape.

  20. Kinetic assembly of block copolymers in solution helical cylindrical micelles and patchy nanoparticles

    Science.gov (United States)

    Zhong, Sheng

    There is always an interest to understand how molecules behave under different conditions. One application of this knowledge is to self-assemble molecules into increasingly complex structures in a simple fashion. Self-assembly of amphiphilic block copolymer in solution has produced a large variety of nanostructures through the manipulation in polymer chemistry, assembly environment, and additives. Moreover, some reports suggest the formation of many polymeric assemblies is driven by kinetic process. The goal of this dissertation is to study the influence of kinetics on the assembly of block copolymer. The study shows kinetic control can be a very effective way to make novel polymeric nanostructures. Two examples discussed here are helical cylindrical micelles and patchy nanoparticles. Helical cylindrical micelles are made from the co-assembly of amphiphilic triblock copolymer poly(acrylic acid)-block-poly(methyl acrylate)- block-polystyrene and organoamine molecules in a mixture of tetrahydrofuran (THF) and water (H2O). This system has already shown promise of achieving many assembled structures. The unique aspects about this system are the use of amine molecules to complex with acid groups and the existence of cosolvent system. Application of amine molecules offers a convenient control over assembled morphology and the introduction of PMA-PS selective solvent, THF, promotes the mobility of the polymer chains. In this study, multivalent organoamine molecules, such as diethylenetriamine and triethylenetetramine, are used to interact with block copolymer in THF/water mixture. As expected, the assembled morphologies are dependent on the polymer architecture, selection and quantity of the organoamine molecules, and solution composition. Under the right conditions, unprecedented, multimicrometer-long, supramolecular helical cylindrical micelles are formed. Both single-stranded and double-stranded helices are found in the same system. These helical structures share

  1. Alteration of helical vortex core without change in flow topology

    DEFF Research Database (Denmark)

    Velte, Clara Marika; Okulov, Valery; Hansen, Martin Otto Laver

    2011-01-01

    topology. The helical symmetry as such is preserved, although the characteristic parameters of helical symmetry of the vortex core transfer from a smooth linear variation to a different trend under the influence of a non-uniform pressure gradient, causing an increase in helical pitch without changing its......The abrupt expansion of the slender vortex core with changes in flow topology is commonly known as vortex breakdown. We present new experimental observations of an alteration of the helical vortex core in wall bounded turbulent flow with abrupt growth in core size, but without change in flow...

  2. Helicity conservation under quantum reconnection of vortex rings.

    Science.gov (United States)

    Zuccher, Simone; Ricca, Renzo L

    2015-12-01

    Here we show that under quantum reconnection, simulated by using the three-dimensional Gross-Pitaevskii equation, self-helicity of a system of two interacting vortex rings remains conserved. By resolving the fine structure of the vortex cores, we demonstrate that the total length of the vortex system reaches a maximum at the reconnection time, while both writhe helicity and twist helicity remain separately unchanged throughout the process. Self-helicity is computed by two independent methods, and topological information is based on the extraction and analysis of geometric quantities such as writhe, total torsion, and intrinsic twist of the reconnecting vortex rings.

  3. Superposition of helical beams by using a Michelson interferometer.

    Science.gov (United States)

    Gao, Chunqing; Qi, Xiaoqing; Liu, Yidong; Weber, Horst

    2010-01-04

    Orbital angular momentum (OAM) of a helical beam is of great interests in the high density optical communication due to its infinite number of eigen-states. In this paper, an experimental setup is realized to the information encoding and decoding on the OAM eigen-states. A hologram designed by the iterative method is used to generate the helical beams, and a Michelson interferometer with two Porro prisms is used for the superposition of two helical beams. The experimental results of the collinear superposition of helical beams and their OAM eigen-states detection are presented.

  4. Progress with helicity injection current drive

    International Nuclear Information System (INIS)

    Jarboe, T.R.; Raman, R.; Nelson, B.A.

    2003-01-01

    Coaxial Helicity Injection (CHI) experiments in the NSTX and HIT-II devices are reported. NSTX has produced toroidal currents of 0.4 MA and pulse lengths of up to 0.33 s. These discharges nearly fill the NSTX main chamber, and show the n=1 rotating distortion characteristic of high-performance CHI plasmas. CHI has been used in HIT-II to provide a closed flux startup plasma for inductive drive. The CHI startup method saves transformer volt-seconds and greatly improves reproducibility and reliability of inductively driven discharges, even in the presence of diminishing wall conditions. (author)

  5. Heat loss by helicity injection in spheromaks

    International Nuclear Information System (INIS)

    Fowler, T.K.

    1994-01-01

    A model is presented for spheromak buildup and decay including thermal diffusivity associated with magnetic turbulence during helicity injection. It is shown that heat loss by magnetic turbulence scales more favorably than gyroBohm transport. Thus gyroBohm scaling for the proposed ignition experiment would be the conservative choice, though present experiments may be dominated by magnetic turbulence. Because of a change in boundary conditions when the gun is turned off, the model may account for the observed increase in electron temperature in CTX after turnoff

  6. Rotation influence on the plasma helical instability

    International Nuclear Information System (INIS)

    Gutkin, T.I.; Tsypin, V.S.; Boleslavskaya, G.I.

    1980-01-01

    The influence of the rotation on helical instability of a plasma with the fixed boundaries (HIFB) is investigated taking into account the compressibility. A case of infinitely long cylinder with distributed current is considered. Cases when a rotating plasma is confined by current magnetic field are analytically considered. It is shown that in the case of the fixed boundary taking into account the compressibility in the HIFB increment increases and the picture of the rotation influence on HIFB considerably changes. Besides, it is shown that in the case of high plasma pressures HIFB can stabilize as a result of the rotation

  7. Site selection under the underground geologic store plan. Procedures of selecting underground geologic stores as disputed by society, science, and politics. Site selection rules; Mit dem Sachplan Geologische Tiefenlager auf Standortsuche. Auswahlverfahren fuer geologische Tiefenlager im Spannungsfeld von Gesellschaft, Wissenschaft und Politik, Regeln fuer die Standortsuche

    Energy Technology Data Exchange (ETDEWEB)

    Aebersold, M. [Bundesamt fuer Energie BFE, Sektion Entsorgung Radioaktive Abfaelle, Bern (Switzerland)

    2008-10-15

    The new Nuclear Power Act and the Nuclear Power Ordinance of 2005 are used in Switzerland to select a site of an underground geologic store for radioactive waste in a substantive planning procedure. The ''Underground Geologic Store Substantive Plan'' is to ensure the possibility to build underground geologic stores in an independent, transparent and fair procedure. The Federal Office for Energy (BFE) is the agency responsible for this procedure. The ''Underground Geologic Store'' Substantive Plan comprises these principles: - The long term protection of people and the environment enjoys priority. Aspects of regional planning, economics and society are of secondary importance. - Site selection is based on the waste volumes arising from the five nuclear power plants currently existing in Switzerland. The Substantive Plan is no precedent for or against future nuclear power plants. - A transparent and fair procedure is an indispensable prerequisite for achieving the objectives of a Substantive Plan, i.e., finding accepted sites for underground geologic stores. The Underground Geologic Stores Substantive Plan is arranged in two parts, a conceptual part defining the rules of the selection process, and an implementation part documenting the selection process step by step and, in the end, naming specific sites of underground geologic stores in Switzerland. The objective is to be able to commission underground geologic stores in 25 or 35 years' time. In principle, 2 sites are envisaged, one for low and intermediate level waste, and one for high level waste. The Swiss Federal Council approved the conceptual part on April 2, 2008. This marks the beginning of the implementation phase and the site selection process proper. (orig.)

  8. Electronic transport in single-helical protein molecules: Effects of multiple charge conduction pathways and helical symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Sourav, E-mail: sourav.kunduphy@gmail.com; Karmakar, S.N.

    2016-07-15

    We propose a tight-binding model to investigate electronic transport properties of single helical protein molecules incorporating both the helical symmetry and the possibility of multiple charge transfer pathways. Our study reveals that due to existence of both the multiple charge transfer pathways and helical symmetry, the transport properties are quite rigid under influence of environmental fluctuations which indicates that these biomolecules can serve as better alternatives in nanoelectronic devices than its other biological counterparts e.g., single-stranded DNA.

  9. Catechol-Acylhydrazone-Liganden für die Bildung heterodinuklearer Helicate

    OpenAIRE

    Latorre Martínez, Irene Cristina

    2011-01-01

    The interest for artificial helical structures has steadily grown since the first definition by Lehn and the investigations done later on. Not only the spectacular properties and potential applications of these compounds are important features of these substances but also their special characteristics are interesting for the supramolecular chemists. The synthesis of ligands with special donor atoms at the coordination sites is the crucial point and makes the selective binding of f- and d- met...

  10. Helical type thermonuclear device and control method

    International Nuclear Information System (INIS)

    Ishigaki, Yukio.

    1990-01-01

    In a conventional helical type thermonuclear device, electric current flows in the toroidal direction under magnetic fields of helical coils and vertical magnetic coils, by which a circulating electric field is caused. Therefore, there is a problem that electrons as a seed are generated by cosmic rays, etc., the electrons are confined in a magnetic field boundary, are accelerated by the circulating electric field, to reach a high energy level, collide against structures in a vacuum vessel and emit a great amount of X-rays. Then, compensation coils for offsetting the magnetic fields generated upon energization and deenergization of the vertical magnetic coils and the power source therefor are disposed at the positions opposing to each other on both sides of the vertical magnetic coils for controlling the variation coefficient rate of electric current upon energization and deenergization of the vertical magnetic coils. Since the compensation coils also offset the magnetic field generated upon energization and deenergization of the vertical magnetic field coils by this control, the circulating magnetic field is not caused in the vacuum vessel to reduce the X-ray radiation by electrons at high energy level. (N.H.)

  11. Determining How Magnetic Helicity Injection Really Works

    International Nuclear Information System (INIS)

    Paul M Bellan

    2001-01-01

    OAK-B135 The goal of the Caltech program is to determine how helicity injection works by investigating the actual dynamics and topological evolution associated with magnetic relaxation. A new coaxial helicity injection source has been constructed and brought into operation. The key feature of this source is that it has maximum geometric simplicity. Besides being important for fusion research, this work also has astrophysical implications. Photos obtained using high-speed cameras show a clear sequence of events in the formation process. In particular, they show initial merging/reconnection processes, jet-like expansion, kinking, and separation of the plasma from the source. Various diagnostics have been developed, including laser induced fluorescence and soft x-ray detection using high speed diodes. Gas valves have been improved and a patent disclosure relating to puffed gas valves has been filed. Presentations on this work have been given in the form of invited talks at several university physics departments that were previously unfamiliar with laboratory plasma experiments

  12. On the motion of multiple helical vortices

    Science.gov (United States)

    Wood, D. H.; Boersma, J.

    2001-11-01

    The analysis of the self-induced velocity of a single helical vortex (Boersma & Wood 1999) is extended to include equally spaced multiple vortices. This arrangement approximates the tip vortices in the far wake of multi-bladed wind turbines, propellers, or rotors in ascending, descending, or hovering flight. The problem is reduced to finding, from the Biot Savart law, the additional velocity of a helix due to an identical helix displaced azimuthally. The resulting Biot Savart integral is further reduced to a Mellin Barnes integral representation which allows the asymptotic expansions to be determined for small and for large pitch. The Biot Savart integral is also evaluated numerically for a total of two, three and four vortices over a range of pitch values. The previous finding that the self-induced velocity at small pitch is dominated by a term inversely proportional to the pitch carries over to multiple vortices. It is shown that a far wake dominated by helical tip vortices is consistent with the one-dimensional representation that leads to the Betz limit on the power output of wind turbines. The small-pitch approximation then allows the determination of the blade&s bound vorticity for optimum power extraction. The present analysis is shown to give reasonable estimates for the vortex circulation in experiments using a single hovering rotor and a four-bladed propeller.

  13. Perspectives on confinement in helical systems

    International Nuclear Information System (INIS)

    Itoh, Kimitaka; Itoh, Sanae

    1989-01-01

    A review on recent experimental results and theoretical models on anomalous transport and density limit in toroidal helical devices is presented. Importance of transport problems is discussed. Experiments on Heliotron-E, Wendelstein-VIIA and new devices, i.e., ATF, Wendelstein-VIIAS and CHS, are reviewed and an overview on confinement property is given. From recent experimental results one sees that there are anomalous transport, which increases with temperature, and density limit, and that they limit the energy confinement time as well as the attainable beta value. The confinement characteristics of the scrape off layer plasma and loss cone loss are discussed, and perspectives on the high temperature plasma are given. These anomalous transport and density limit will be difficult obstacles in realizing a reactor grade plasma in helical systems. It is an urgent task to draw a realistic picture of the confinement based on the present data base. The relevant knowledge now would be critically essential for the successful development of the research in 1990's. (author) 102 refs

  14. Neutrino helicity reversal and fundamental symmetries

    International Nuclear Information System (INIS)

    Jentschura, U D; Wundt, B J

    2014-01-01

    A rather elusive helicity reversal occurs in a gedanken experiment in which a massive left-handed Dirac neutrino, traveling at a velocity u < c, is overtaken on a highway by a speeding vehicle (traveling at velocity v with u < v < c). Namely, after passing the neutrino, looking back, one would see a right-handed neutrino (which has never been observed in nature). The Lorentz-invariant mass of the right-handed neutrino is still the same as before the passing. The gedanken experiment thus implies the existence of right-handed, light neutrinos, which are not completely sterile. Furthermore, overtaking a bunch of massive right-handed Dirac neutrinos leads to gradual de-sterilization. We discuss the helicity reversal and the concomitant sterilization and de-sterilization mechanisms by way of an illustrative example calculation, with a special emphasis on massive Dirac and Majorana neutrinos. We contrast the formalism with a modified Dirac neutrino described by a Dirac equation with a pseudoscalar mass term proportional to the fifth current. (paper)

  15. Quality assurance of a helical tomotherapy machine

    International Nuclear Information System (INIS)

    Fenwick, J D; Tome, W A; Jaradat, H A; Hui, S K; James, J A; Balog, J P; DeSouza, C N; Lucas, D B; Olivera, G H; Mackie, T R; Paliwal, B R

    2004-01-01

    Helical tomotherapy has been developed at the University of Wisconsin, and 'Hi-Art II' clinical machines are now commercially manufactured. At the core of each machine lies a ring-gantry-mounted short linear accelerator which generates x-rays that are collimated into a fan beam of intensity-modulated radiation by a binary multileaf, the modulation being variable with gantry angle. Patients are treated lying on a couch which is translated continuously through the bore of the machine as the gantry rotates. Highly conformal dose-distributions can be delivered using this technique, which is the therapy equivalent of spiral computed tomography. The approach requires synchrony of gantry rotation, couch translation, accelerator pulsing and the opening and closing of the leaves of the binary multileaf collimator used to modulate the radiation beam. In the course of clinically implementing helical tomotherapy, we have developed a quality assurance (QA) system for our machine. The system is analogous to that recommended for conventional clinical linear accelerator QA by AAPM Task Group 40 but contains some novel components, reflecting differences between the Hi-Art devices and conventional clinical accelerators. Here the design and dosimetric characteristics of Hi-Art machines are summarized and the QA system is set out along with experimental details of its implementation. Connections between this machine-based QA work, pre-treatment patient-specific delivery QA and fraction-by-fraction dose verification are discussed

  16. Effects of Tax Depreciation Rules on Firms' Investment Decisions in an Inflationary Phase: Comparison of Net Present Values in Selected OECD Countries

    OpenAIRE

    Chang Woon Nam

    2001-01-01

    This study compares incentive effects of various tax depreciation methods which are currently employed in selected OECD countries. Their generosity is determined on the basis of Samuelson’s true economic depreciation. For this purpose, the present value model is applied. The central issue is that the so-called historical cost accounting method, which is adopted in practice when calculating the corporate tax base, causes fictitious profits in inflationary phases that should also be taxed. Th...

  17. Energy fluxes in helical magnetohydrodynamics and dynamo action

    Indian Academy of Sciences (India)

    ... large-scale magnetic field arising due to non-helical interactions and (2) inverse energy flux of magnetic energy caused by helical interactions. Based on our flux results, a primitive model for galactic dynamo has been constructed. Our calculations yield dynamo time-scale for a typical galaxy to be of the order of 108 years.

  18. Alpha-Effect, Current and Kinetic Helicities for Magnetically Driven ...

    Indian Academy of Sciences (India)

    tribpo

    Key words. Sun—dynamo, helicity, turbulent convection. Extended abstract. Recent numerical simulations lead to the result that turbulence is much more mag- netically driven than believed. ... positive (and negative in the northern hemisphere), this being just opposite to what occurs for the current helicity which is negative ...

  19. Space vehicle electromechanical system and helical antenna winding fixture

    Science.gov (United States)

    Judd, Stephen; Dallmann, Nicholas; Guenther, David; Enemark, Donald; Seitz, Daniel; Martinez, John; Storms, Steven

    2017-12-26

    A space vehicle electromechanical system may employ an architecture that enables convenient and practical testing, reset, and retesting of solar panel and antenna deployment on the ground. A helical antenna winding fixture may facilitate winding and binding of the helical antenna.

  20. Low-energy properties of fractional helical Luttinger liquids

    NARCIS (Netherlands)

    Meng, T.; Fritz, L.|info:eu-repo/dai/nl/371569559; Schuricht, D.|info:eu-repo/dai/nl/369284690; Loss, D.

    2014-01-01

    We investigate the low-energy properties of (quasi) helical and fractional helical Luttinger liquids. In particular, we calculate the Drude peak of the optical conductivity, the density of states, as well as charge transport properties of the interacting system with and without attached Fermi liquid

  1. A helical naphthopyran dopant for photoresponsive cholesteric liquid crystals

    OpenAIRE

    Kim, Yuna; Frigoli, Michel; Vanthuyne, Nicolas; Tamaoki, Nobuyuki

    2017-01-01

    The first photoresponsive cholesteric liquid crystal comprising a photoisomerizable helical naphthopyran derivative dopant and a nematic liquid crystal is reported. An unprecedented helical twisting power switching ratio of over 90% allowed us to demonstrate multi-cycle rotational motion of micro-objects by UV light irradiation.

  2. Helical modes generate antimagnetic rotational spectra in nuclei

    Science.gov (United States)

    Malik, Sham S.

    2018-03-01

    A systematic analysis of the antimagnetic rotation band using r -helicity formalism is carried out for the first time. The observed octupole correlation in a nucleus is likely to play a role in establishing the antimagnetic spectrum. Such octupole correlations are explained within the helical orbits. In a rotating field, two identical fermions (generally protons) with paired spins generate these helical orbits in such a way that its positive (i.e., up) spin along the axis of quantization refers to one helicity (right-handedness) while negative (down) spin along the same quantization-axis decides another helicity (left-handedness). Since the helicity remains invariant under rotation, therefore, the quantum state of a fermion is represented by definite angular momentum and helicity. These helicity represented states support a pear-shaped structure of a rotating system having z axis as the symmetry axis. A combined operation of parity, time-reversal, and signature symmetries ensures an absence of one of the signature partner band from the observed antimagnetic spectrum. This formalism has also been tested for the recently observed negative parity Δ I =2 antimagnetic spectrum in odd-A 101Pd nucleus and explains nicely its energy spectrum as well as the B (E 2 ) values. Further, this formalism is found to be fully consistent with twin-shears mechanism popularly known for such type of rotational bands. It also provides significant clue for extending these experiments in various mass regions spread over the nuclear chart.

  3. Experimental investigation of solar powered diaphragm and helical pumps

    Science.gov (United States)

    For several years, many types of solar powered water pumping systems were evaluated, and in this paper, diaphragm and helical solar photovoltaic (PV) powered water pumping systems are discussed. Data were collected on diaphragm and helical pumps which were powered by different solar PV arrays at mul...

  4. Strong coupling between a permalloy ferromagnetic contact and helical edge channel in a narrow HgTe quantum well

    Energy Technology Data Exchange (ETDEWEB)

    Kononov, A.; Egorov, S. V. [Russian Academy Sciences, Institute of Solid State Physics (Russian Federation); Kvon, Z. D.; Mikhailov, N. N.; Dvoretsky, S. A. [Institute of Semiconductor Physics (Russian Federation); Deviatov, E. V., E-mail: dev@issp.ac.ru [Russian Academy Sciences, Institute of Solid State Physics (Russian Federation)

    2016-11-15

    We experimentally investigate spin-polarized electron transport between a permalloy ferromagnet and the edge of a two-dimensional electron system with band inversion, realized in a narrow, 8 nm wide, HgTe quantum well. In zero magnetic field, we observe strong asymmetry of the edge potential distribution with respect to the ferromagnetic ground lead. This result indicates that the helical edge channel, specific for the structures with band inversion even at the conductive bulk, is strongly coupled to the ferromagnetic side contact, possibly due to the effects of proximity magnetization. This allows selective and spin-sensitive contacting of helical edge states.

  5. Stimuli-Directed Helical Chirality Inversion and Bio-Applications

    Directory of Open Access Journals (Sweden)

    Ziyu Lv

    2016-08-01

    Full Text Available Helical structure is a sophisticated ubiquitous motif found in nature, in artificial polymers, and in supramolecular assemblies from microscopic to macroscopic points of view. Significant progress has been made in the synthesis and structural elucidation of helical polymers, nevertheless, a new direction for helical polymeric materials, is how to design smart systems with controllable helical chirality, and further use them to develop chiral functional materials and promote their applications in biology, biochemistry, medicine, and nanotechnology fields. This review summarizes the recent progress in the development of high-performance systems with tunable helical chirality on receiving external stimuli and discusses advances in their applications as drug delivery vesicles, sensors, molecular switches, and liquid crystals. Challenges and opportunities in this emerging area are also presented in the conclusion.

  6. Helicity conservation and twisted Seifert surfaces for superfluid vortices.

    Science.gov (United States)

    Salman, Hayder

    2017-04-01

    Starting from the continuum definition of helicity, we derive from first principles its different contributions for superfluid vortices. Our analysis shows that an internal twist contribution emerges naturally from the mathematical derivation. This reveals that the spanwise vector that is used to characterize the twist contribution must point in the direction of a surface of constant velocity potential. An immediate consequence of the Seifert framing is that the continuum definition of helicity for a superfluid is trivially zero at all times. It follows that the Gauss-linking number is a more appropriate definition of helicity for superfluids. Despite this, we explain how a quasi-classical limit can arise in a superfluid in which the continuum definition for helicity can be used. This provides a clear connection between a microscopic and a macroscopic description of a superfluid as provided by the Hall-Vinen-Bekarevich-Khalatnikov equations. This leads to consistency with the definition of helicity used for classical vortices.

  7. High performance operational limits of tokamak and helical systems

    International Nuclear Information System (INIS)

    Yamazaki, Kozo; Kikuchi, Mitsuru

    2003-01-01

    The plasma operational boundaries of tokamak and helical systems are surveyed and compared with each other. Global confinement scaling laws are similar and gyro-Bohm like, however, local transport process is different due to sawtooth oscillations in tokamaks and ripple transport loss in helical systems. As for stability limits, achievable tokamak beta is explained by ideal or resistive MHD theories. On the other hand, beta values obtained so far in helical system are beyond ideal Mercier mode limits. Density limits in tokamak are often related to the coupling between radiation collapse and disruptive MHD instabilities, but the slow radiation collapse is dominant in the helical system. The pulse length of both tokamak and helical systems is on the order of hours in small machines, and the longer-pulsed good-confinement plasma operations compatible with radiative divertors are anticipated in both systems in the future. (author)

  8. On Helical Projection and Its Application in Screw Modeling

    Directory of Open Access Journals (Sweden)

    Riliang Liu

    2014-04-01

    Full Text Available As helical surfaces, in their many and varied forms, are finding more and more applications in engineering, new approaches to their efficient design and manufacture are desired. To that end, the helical projection method that uses curvilinear projection lines to map a space object to a plane is examined in this paper, focusing on its mathematical model and characteristics in terms of graphical representation of helical objects. A number of interesting projective properties are identified in regard to straight lines, curves, and planes, and then the method is further investigated with respect to screws. The result shows that the helical projection of a cylindrical screw turns out to be a Jordan curve, which is determined by the screw's axial profile and number of flights. Based on the projection theory, a practical approach to the modeling of screws and helical surfaces is proposed and illustrated with examples, and its possible application in screw manufacturing is discussed.

  9. Internal transport barrier physics in helical systems

    International Nuclear Information System (INIS)

    Yokoyama, M.; Minami, T.; Fujisawa, A.; Herranz, J.; Ida, K.; Yamagishi, O.; Yamada, H.; Maaberg, H.; Beidler, C.D.; Dinklage, A.; Estrada, T.; Castejon, F.; Murakami, S.

    2005-01-01

    The electron internal transport barrier (eITB) has been observed in wide range of helical systems, such as CHS [eg.,1], LHD [eg., 2], TJ-II [eg., 3] and W7-AS [eg., 4]. The eITB isA defined as highly peaked electron temperature (Te) profile with strongly positive radial electric field (Er) in the central region. These observations are reviewed in this paper to understand the device-independent common findings and also to draw the main differences. This is the first report from the International Stellarator Profile Database Activity. The formation of the strong central positive Er has been understood mainly as a result of the ambipolarity of neoclassical electron and ion fluxes, although some additional convective electron flux such as driven by ECRH is required in some situations. This 'neoclassical' physics peculiar to low collisional regime of helical plasmas provides the commonly observed existence of the ECRH power threshold (which is also depending on the density). This is contrastive characteristics to the ITB observed in tokamaks. The dependence of the ECRH power threshold on the magnetic configuration and on the heating scenario among these devices are currently being examined by taking the effective ripple and the trapped particle fraction as parameters to achieve the comprehensive understanding. The roles of low order rational surfaces on the onset of eITB formation and also on its radial size (location of the footpoint of the eITB) have been indicated in inward shifted configurations in LHD (depending on the relative locations of heating position and 2/1 island) and TJ-II (eITB becomes possible at higher density when 3/2 rational is introduced in the plasma core region). It is speculated that, for the latter case, the resonance causes an extra electron flux to trigger the positive Er. The interplay between low order rational surfaces and the formation of eITB still waits for the systematic experiment and theoretical analysis. The external controllability

  10. Patterns of uterine enhancement with helical CT

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, H.; Loyer, E.M.; Charnsangavej, C. [Department of Diagnostic Radiology, Box 57, The University of Texas, M.D. Anderson Cancer Center, 1515 Holcombe Blvd. Houston, TX 77030 (United States); Minami, M. [Department of Radiology, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo 113 (Japan)

    1998-10-01

    Objective: The purpose of this study was to evaluate the enhancement characteristics of the normal uterine body and cervix using dynamic contrast-enhanced helical CT. Methods: Thirty-eight women scheduled for pelvic CT for non-gynecologic malignancies underwent dynamic contrast-enhanced helical CT of the pelvis. Data acquisition was during the arterial phase (30-45 s after the start of injection), the parenchymal phase (90-120 s after the start of injection), and delayed phase (3-9 min after the start of injection). The images were evaluated by four radiologists for the pattern of myometrial and cervical enhancement. Correlation was made with the age and menstrual status of the patients. Results: In the uterine body, three types of enhancement were observed. Type 1 enhancement, seen in 16 patients (42%), was characterized by the visualization of a subendometrial zone of enhancement, 30-120 s after the start of injection. Eight of these patients also showed an enhancing zone in the outer myometrium. Both zones were transitory, and in all cases, the uterus became homogeneous in the delayed phase. This pattern was seen predominantly in premenopausal women with a mean age of 34 years. Type 2 enhancement, seen in 17 cases (45%), was defined by the absence of subendometrial enhancement in the early phase. Enhancement was either diffuse from the outset or originated in the outer myometrium. This pattern was seen nearly equally in premenopausal and postmenopausal women with a mean age of 40 years. Type 3 enhancement was seen in five postmenopausal patients (13%) with a mean age of 53 years and was characterized by faint diffuse enhancement. In the cervix, a zonal pattern of enhancement defining inner and outer stroma was seen in 23 patients (61%). Fifteen patients were premenopausal and eight were postmenopausal. Conclusion: In this study, we have shown a transitory zonal distribution of the contrast in the myometrium and cervix using dynamic contrast-enhanced helical CT

  11. Patterns of uterine enhancement with helical CT

    International Nuclear Information System (INIS)

    Kaur, H.; Loyer, E.M.; Charnsangavej, C.; Minami, M.

    1998-01-01

    Objective: The purpose of this study was to evaluate the enhancement characteristics of the normal uterine body and cervix using dynamic contrast-enhanced helical CT. Methods: Thirty-eight women scheduled for pelvic CT for non-gynecologic malignancies underwent dynamic contrast-enhanced helical CT of the pelvis. Data acquisition was during the arterial phase (30-45 s after the start of injection), the parenchymal phase (90-120 s after the start of injection), and delayed phase (3-9 min after the start of injection). The images were evaluated by four radiologists for the pattern of myometrial and cervical enhancement. Correlation was made with the age and menstrual status of the patients. Results: In the uterine body, three types of enhancement were observed. Type 1 enhancement, seen in 16 patients (42%), was characterized by the visualization of a subendometrial zone of enhancement, 30-120 s after the start of injection. Eight of these patients also showed an enhancing zone in the outer myometrium. Both zones were transitory, and in all cases, the uterus became homogeneous in the delayed phase. This pattern was seen predominantly in premenopausal women with a mean age of 34 years. Type 2 enhancement, seen in 17 cases (45%), was defined by the absence of subendometrial enhancement in the early phase. Enhancement was either diffuse from the outset or originated in the outer myometrium. This pattern was seen nearly equally in premenopausal and postmenopausal women with a mean age of 40 years. Type 3 enhancement was seen in five postmenopausal patients (13%) with a mean age of 53 years and was characterized by faint diffuse enhancement. In the cervix, a zonal pattern of enhancement defining inner and outer stroma was seen in 23 patients (61%). Fifteen patients were premenopausal and eight were postmenopausal. Conclusion: In this study, we have shown a transitory zonal distribution of the contrast in the myometrium and cervix using dynamic contrast-enhanced helical CT

  12. [The Aut-idem Rule and the Importance of Patient-Individual Selection of Inhalers for the Therapy of Airway Diseases in Practices of Pneumologists and General Practitioners - Assessment and Implementation by Pneumologists and General Practitioners].

    Science.gov (United States)

    Hering, T; Andres, J; Mohrlang, C; Redeker, M; Schwarz, E

    2018-03-01

    Drug therapy of obstructive airway diseases mainly relies on inhaled medication. The success of this therapy depends primarily on the selection of the appropriate inhaler considering patient's choice and the correct application. The aut-idem-rule, an active exclusion of the optional substitution by the pharmacist, allows prescribing physicians to ensure the delivery of a particular inhaler, which was selected for that patient, who was trained to use specifically that inhaler. This survey shows that pneumologists and, to a greater extent general practitioners, do not consistently make use of this option, although they unanimously agree on the importance of targeted inhaler selection. As a result, patients may receive different inhalers in the pharmacy, where the inhaler is chosen under consideration of market-driven aspects such as rebate contracts or stock. This causes that patients get confused by the exchange of their inhaler. Thus the exchange of the inhaler by the pharmacist leads to uncertainty and application problems in patients. Hence, the success of the comparatively complex inhaled therapy is endangered. This could be prevented, if prescribing physicians were informed and supported consistently regarding the use of aut-idem exclusion to ensure an optimal therapy for each individual patient. © Georg Thieme Verlag KG Stuttgart · New York.

  13. Helical spin rotators and snakes for RHIC

    International Nuclear Information System (INIS)

    Ptitsin, V.I.; Shatunov, Yu.M.; Peggs, S.

    1995-01-01

    The RHIC collider, now under construction at BNL, will have the possibility of polarized proton-proton collisions up to a beam energy of 250 Gev. Polarized proton beams of such high energy can be only obtained with the use of siberian snakes, a special kind of spin rotator that rotates the particle spin by 180 degree around an axis lying in the horizontal plane. Siberian snakes help to preserve the beam polarization while numerous spin depolarizing resonances are crossed, during acceleration. In order to collide longitudinally polarized beams, it is also planned to install spin rotators around two interaction regions. This paper discusses snake and spin rotator designs based on sequences of four helical magnets. The schemes that were chosen to be applied at RHIC are presented

  14. ATLAS helicity analyses in beauty hadron decays

    CERN Document Server

    Smizanska, M

    2000-01-01

    The ATLAS detector will allow a precise spatial reconstruction of the kinematics of B hadron decays. In combination with the efficient lepton identification applied already at trigger level, ATLAS is expected to provide large samples of exclusive decay channels cleanly separable from background. These data sets will allow spin-dependent analyses leading to the determination of production and decay parameters, which are not accessible if the helicity amplitudes are not separated. Measurement feasibility studies for decays B/sub s //sup 0/ to J/ psi phi and Lambda /sub b//sup 0/ to Lambda J/ psi , presented in this document, show the experimental precisions that can be achieved in determination of B/sub s//sup 0/ and Lambda /sub b //sup 0/ characteristics. (19 refs).

  15. Conditioner for a helically transported electron beam

    International Nuclear Information System (INIS)

    Wang, Changbiao.

    1992-05-01

    The kinetic theory is developed to investigate a conditioner for a helically transported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the conditioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron's relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one-third of its initial value

  16. Conditioner for a helically transported electron beam

    International Nuclear Information System (INIS)

    Wang, C.

    1992-05-01

    The kinetic theory is developed to investigate a conditioner for a helically imported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the conditioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron's relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one-third of its initial value

  17. Microinstability Studies for the Large Helical Device

    International Nuclear Information System (INIS)

    Rewoldt, G.; Ku, L.-P.; Tang, W.M.; Sugama, H.; Nakajima, N.; Watanabe, K.Y.; Murakami, S.; Yamada, H.; Cooper, W.A.

    2002-01-01

    Fully kinetic assessments of the stability properties of toroidal drift modes have been obtained for cases for the Large Helical Device (LHD). This calculation employs the comprehensive linear microinstability code FULL, as recently extended for nonaxisymmetric systems. The code retains the important effects in the linearized gyrokinetic equation, using the lowest-order ''ballooning representation'' for high toroidal mode number instabilities in the electrostatic limit. These effects include trapped particles, FLR, transit and bounce and magnetic drift frequency resonances, etc., for any number of plasma species. Results for toroidal drift waves destabilized by trapped electrons and ion temperature gradients are presented, using numerically-calculated three-dimensional MHD equilibria. These are reconstructed from experimental measurements. Quasilinear fluxes of particles and energy for each species are also calculated. Pairs of LHD discharges with different magnetic axis positions and with and without pellet injection are compared

  18. Characteristic features of edge transport barrier formed in helical divertor configuration of the Large Helical Device

    International Nuclear Information System (INIS)

    Toi, K.; Ohdachi, S.; Watanabe, F.

    2006-10-01

    In a helical divertor configuration of the Large Helical Device (LHD), transport barrier was formed through low to high confinement (L-H) transition in the plasma edge region including ergodic field layer of which region is in the magnetic hill. The plasma stored energy or the averaged bulk plasma beta dia > (derived from diamagnetic measurement) starts to increase just after the transition. In the case that both dia > and line-averaged electron density e > at the transition are relatively high as dia >≥1.5% and e >≥2x10 19 m -3 , the increase is hampered by rapid growth of edge MHD modes and/or small ELM like activities just after the transition. On the other hand, the transition at lower e > (≤1.5x10 19 m -3 ) and dia > (<2%) leads to a continuous increase in the stored energy with a time scale longer than the global energy confinement time, without suffering from these MHD activities near the edge. The ETB typically formed in electron density profile extends into ergodic field layer defined in the vacuum field. The width of ETB is almost independent of the toroidal field strength from 0.5T to 1.5T and is much larger than the poloidal ion gyro-radius. When resonant helical field perturbations are applied to expand a magnetic island size at the rational surface of the rotational transform ι/2π=1 near the edge, the L-H transition is triggered at lower electron density compared with the case without the field perturbations. The application of large helical field perturbations also suppresses edge MHD modes and ELM like activities. (author)

  19. Helical twisting in nemato-cholesteric systems based on cholesterol derivatives and photosensitive azoxy compounds

    Energy Technology Data Exchange (ETDEWEB)

    Serbina, M. I.; Kasian, N. A.; Lisetski, L. N., E-mail: lisetski@isma.kharkov.ua [NAS of Ukraine, Institute for Scintillation Materials, STC ' Institute for Single Crystals' (Ukraine)

    2013-01-15

    For cholesteric liquid crystal systems containing photosensitive nematic ZhK-440 and a mixture of cholesterol derivatives, changes in helical twisting induced by UV radiation were studied. The UV-induced shift of selective reflection maximum {lambda}{sub max} was shown to depend upon concentration of the nematic component. For low concentrations of ZhK-440, {lambda}{sub max} increases, which correlates with corresponding changes with increasing temperature. For higher concentrations, {lambda}{sub max} decreases, regardless of the temperature behavior of the system. A theoretical description of the available experimental data is proposed on the basis of development of molecular models of helical twisting, including an assumed possibility of ordered orientation of short molecular axes of cis-isomers formed as a result of UV irradiation, which is determined by the sense of the cholesteric helix already present in the system.

  20. Modeling of Heat Transfer in the Helical-Coil Heat Exchanger for the Reactor Facility "UNITERM"

    Directory of Open Access Journals (Sweden)

    V. I. Solonin

    2014-01-01

    Full Text Available Circuit heat sink plays an important role in the reactor system. Therefore it imposes high requirements for quality of determining thermal-hydraulic parameters. This article is aimed at modeling of heat exchange process of the helical-coil heat exchanger, which is part of the heat sink circuit of the reactor facility "UNITERM."The simulation was performed using hydro-gas-dynamic software package ANSYS CFX. Computational fluid dynamics of this package allows us to perform calculations in a threedimensional setting, giving an idea of the fluid flow nature. The purpose of the simulation was to determine the parameters of the helical-coil heat exchanger (temperature, velocity at the outlet of the pipe and inter-tubular space, pressure drop, and the nature of the fluid flow of primary and intermediate coolants. Geometric parameters of the model were determined using the preliminary calculations performed by the criterion equations. In calculations Turbulence models k-ε RNG, Shear Stress Transport (SST are used. The article describes selected turbulence models, and considers relationship with wall function.The calculation results allow us to give the values obtained for thermal-hydraulic parameters, to compare selected turbulence models, as well as to show distribution patterns of the coolant temperature, pressure, and velocity at the outlet of the intermediate cooler.Calculations have shown that:- maximum values of primary coolant temperature at the outlet of the heat exchanger surface are encountered in the space between the helical-coil tubes;- higher temperatures of intermediate coolant at the outlet of the coils (in space of helicalcoil tubes are observed for the peripheral row;- primary coolant movement in the inter-tubular space of helical-coil surface is formed as a spiral flow, rather than as a in-line tube bank cross flow.

  1. General architecture of the alpha-helical globule.

    Science.gov (United States)

    Murzin, A G; Finkelstein, A V

    1988-12-05

    A model is presented for the arrangement of alpha-helices in globular proteins. In the model, helices are placed on certain ribs of "quasi-spherical" polyhedra. The polyhedra are chosen so as to allow the close packing of helices around a hydrophobic core and to stress the collective interactions of the individual helices. The model predicts a small set of stable architectures for alpha-helices in globular proteins and describes the geometries of the helix packings. Some of the predicted helix arrangements have already been observed in known protein structures; others are new. An analysis of the three-dimensional structures of all proteins for which co-ordinates are available shows that the model closely approximates the arrangements and packing of helices actually observed. The average deviations of the real helix axes from those in the model polyhedra is +/- 20 degrees in orientation and +/- 2 A in position (1 A = 0.1 nm). We also show that for proteins that are not homologous, but whose helix arrangements are described by the same polyhedron, the root-mean-square difference in the position of the C alpha atoms in the helices is 1.6 to 3.0 A.

  2. MAGNETIC HELICITY FLUX IN THE PRESENCE OF SHEAR

    International Nuclear Information System (INIS)

    Hubbard, Alexander; Brandenburg, Axel

    2011-01-01

    Magnetic helicity has risen to be a major player in dynamo theory, with the helicity of the small-scale field being linked to the dynamo saturation process for the large-scale field. It is a nearly conserved quantity, which allows its evolution equation to be written in terms of production and flux terms. The flux term can be decomposed in a variety of fashions. One particular contribution that has been expected to play a significant role in dynamos in the presence of mean shear was isolated by Vishniac and Cho. Magnetic helicity fluxes are explicitly gauge dependent however, and the correlations that have come to be called the Vishniac-Cho flux were determined in the Coulomb gauge, which turns out to be fraught with complications in shearing systems. While the fluxes of small-scale helicity are explicitly gauge dependent, their divergences can be gauge independent. We use this property to investigate magnetic helicity fluxes of the small-scale field through direct numerical simulations in a shearing-box system and find that in a numerically usable gauge the divergence of the small-scale helicity flux vanishes, while the divergence of the Vishniac-Cho flux remains finite. We attribute this seeming contradiction to the existence of horizontal fluxes of small-scale magnetic helicity with finite divergences.

  3. Magnetic Helicity Flux in the Presence of Shear

    Science.gov (United States)

    Hubbard, Alexander; Brandenburg, Axel

    2011-01-01

    Magnetic helicity has risen to be a major player in dynamo theory, with the helicity of the small-scale field being linked to the dynamo saturation process for the large-scale field. It is a nearly conserved quantity, which allows its evolution equation to be written in terms of production and flux terms. The flux term can be decomposed in a variety of fashions. One particular contribution that has been expected to play a significant role in dynamos in the presence of mean shear was isolated by Vishniac & Cho. Magnetic helicity fluxes are explicitly gauge dependent however, and the correlations that have come to be called the Vishniac-Cho flux were determined in the Coulomb gauge, which turns out to be fraught with complications in shearing systems. While the fluxes of small-scale helicity are explicitly gauge dependent, their divergences can be gauge independent. We use this property to investigate magnetic helicity fluxes of the small-scale field through direct numerical simulations in a shearing-box system and find that in a numerically usable gauge the divergence of the small-scale helicity flux vanishes, while the divergence of the Vishniac-Cho flux remains finite. We attribute this seeming contradiction to the existence of horizontal fluxes of small-scale magnetic helicity with finite divergences.

  4. Magnetic Helicities and Dynamo Action in Magneto-rotational Turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Bodo, G.; Rossi, P. [INAF/Osservatorio Astrofisico di Torino, Strada Osservatorio 20, I-10025 Pino Torinese (Italy); Cattaneo, F. [Department of Astronomy and Astrophysics, The University of Chicago, 5640 S. Ellis Avenue, Chicago IL 60637 (United States); Mignone, A., E-mail: bodo@oato.inaf.it [Dipartimento di Fisica, Università degli Studi di Torino, Via Pietro Giuria 1, 10125 Torino (Italy)

    2017-07-10

    We examine the relationship between magnetic flux generation, taken as an indicator of large-scale dynamo action, and magnetic helicity, computed as an integral over the dynamo volume, in a simple dynamo. We consider dynamo action driven by magneto-rotational turbulence (MRT) within the shearing-box approximation. We consider magnetically open boundary conditions that allow a flux of helicity in or out of the computational domain. We circumvent the problem of the lack of gauge invariance in open domains by choosing a particular gauge—the winding gauge—that provides a natural interpretation in terms of the average winding number of pairwise field lines. We use this gauge precisely to define and measure the helicity and the helicity flux for several realizations of dynamo action. We find in these cases that the system as a whole does not break reflectional symmetry and that the total helicity remains small even in cases when substantial magnetic flux is generated. We find no particular connection between the generation of magnetic flux and the helicity or the helicity flux through the boundaries. We suggest that this result may be due to the essentially nonlinear nature of the dynamo processes in MRT.

  5. FeynRules - Feynman rules made easy

    OpenAIRE

    Christensen, Neil D.; Duhr, Claude

    2008-01-01

    In this paper we present FeynRules, a new Mathematica package that facilitates the implementation of new particle physics models. After the user implements the basic model information (e.g. particle content, parameters and Lagrangian), FeynRules derives the Feynman rules and stores them in a generic form suitable for translation to any Feynman diagram calculation program. The model can then be translated to the format specific to a particular Feynman diagram calculator via F...

  6. Delayed rule following

    OpenAIRE

    Schmitt, David R.

    2001-01-01

    Although the elements of a fully stated rule (discriminative stimulus [SD], some behavior, and a consequence) can occur nearly contemporaneously with the statement of the rule, there is often a delay between the rule statement and the SD. The effects of this delay on rule following have not been studied in behavior analysis, but they have been investigated in rule-like settings in the areas of prospective memory (remembering to do something in the future) and goal pursuit. Discriminative even...

  7. High-n helicity-induced shear Alfven eigenmodes

    International Nuclear Information System (INIS)

    Nakajima, N.; Cheng, C.Z.; Okamoto, M.

    1992-05-01

    The high-n Helicity-induced shear Alfven Eigenmodes (HAE) are considered both analytically and numerically for the straight helical magnetic system, where n is the toroidal mode number. The eigenmode equation for the high-n HAE modes is derived along the field line and with the aid of the averaging method is shown to reduce to the Mathieu equation asymptotically. The discrete HAE modes are shown to exist inside the continuum spectrum gaps. The continuous spectrum gaps appear around ω 2 = ω A 2 [N(lι-m)/2] 2 for N = 1,2,.., where ω A is the toroidal Alfven transit frequency, and l, m, and ι are the polarity of helical coils, the toroidal pitch number of helical coils, and the rotational transform, respectively. For the same ω A and ι, the frequency of the helical continuum gap is larger than that of the continuum gap in tokamak plasmas by |l-ι -1 m|. The polarity of helical coils l plays a crucial role in determining the spectrum gaps and the properties of the high-n HAE modes. The spectrum gaps near the magnetic axis are created by the helical ripple with circular flux surfaces for l = 1, and ≥ 3 helicals. For l = 2 helical systems, the spectrum gaps are created by the ellipticity of the flux surfaces. These analytical results for the continuum gaps and the existence of the high-n HAE modes in the continuum gaps are confirmed numerically for the l = 2 case, and we find that the HAE modes exist for mode structures with the even and the odd parities. (author)

  8. Radiation Field of a Square, Helical Beam Antenna

    DEFF Research Database (Denmark)

    Knudsen, Hans Lottrup

    1952-01-01

    square helices are used. Further, in connection with corresponding rigorous formulas for the field from a circular, helical antenna with a uniformly progressing current wave of constant amplitude the present formulas may be used for an investigation of the magnitude of the error introduced in Kraus......' approximate calculation of the field from a circular, helical antenna by replacing this antenna with an ``equivalent'' square helix. This investigation is carried out by means of a numerical example. The investigation shows that Kraus' approximate method of calculation yields results in fair agreement...

  9. Theoretical modeling of transport barriers in helical plasmas

    International Nuclear Information System (INIS)

    Toda, S.; Itoh, K.; Ohyabu, N.

    2008-10-01

    A unified transport modelling to explain electron Internal Transport Barriers (e-ITB) in helical plasmas and Internal Diffusion Barriers (IDB) observed in Large Helical Device (LHD) is proposed. The e-ITB can be predicted with the effect of zonal flows to obtain the e-ITB in the low collisional regime when the radial variation of the particle anomalous diffusivity is included. Transport analysis in this article can newly show that the particle fuelling induces the IDB formation when this unified transport modelling is used in the high collisional regime. The density limit for the IDB in helical plasmas is also examined including the effect of the radiation loss. (author)

  10. Drift mode calculations for the Large Helical Device

    International Nuclear Information System (INIS)

    Rewoldt, G.; Ku, L.-P.; Tang, W.M.; Sugama, H.; Nakajima, N.; Watanabe, K.Y.; Murakami, S.; Yamada, H.; Cooper, W.A.

    2000-01-01

    A fully kinetic assessment of the stability properties of toroidal drift modes has been obtained for a case for the Large Helical Device (LHD) [A.Iiyoshi, et al., Plasma Physics and Controlled Nuclear Fusion Research, 1998, Nucl.Fusion 39, 1245 (1999)]. This calculation retains the important effects in the linearized gyrokinetic equation, using the lowest-order ''ballooning representation'' for high toroidal mode number instabilities in the electrostatic limit. Results for toroidal drift waves destabilized by trapped particle dynamics and ion temperature gradients are presented, using three-dimensional magnetohydrodynamics equilibria reconstructed from experimental measurements. The effects of helically-trapped particles and helical curvature are investigated

  11. Experimental Evidence of Helical Flow in Porous Media

    DEFF Research Database (Denmark)

    Ye, Yu; Chiogna, Gabriele; Cirpka, Olaf A.

    2015-01-01

    Helical flow leads to deformation of solute plumes and enhances transverse mixing in porous media. We present experiments in which macroscopic helical flow is created by arranging different materials to obtain an anisotropic macroscopic permeability tensor with spatially variable orientation....... The resulting helical flow entails twisting streamlines which cause a significant increase in lateral mass exchange and thus a large enhancement of plume dilution (up to 235%) compared to transport in homogenous media. The setup may be used to effectively mix solutes in parallel streams similarly to static...... mixers, but in porous media....

  12. Linear local stability of electrostatic drift modes in helical systems

    International Nuclear Information System (INIS)

    Yamagishi, O.; Nakajima, N.; Sugama, H.; Nakamura, Y.

    2003-01-01

    We investigate the stability of the drift wave in helical systems. For this purpose, we solve the linear local gyrokinetic-Poisson equation, in the electrostatic regime. As a model of helical plasmas, Large helical Device (LHD) is considered. The equation we apply is rather exact in the framework of linear gyrokinetic theory, where only the approximation is the ballooning representation. In this paper, we consider only collisionless cases. All the frequency regime can be naturally reated without any assumptions, and in such cases, ion temperature gradient modes (ITG), trapped electron modes (TEM), and electron temperature gradient modes (ETG) are expected to become unstable linearly independently. (orig.)

  13. Magnetic Helical Micro- and Nanorobots: Toward Their Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Famin Qiu

    2015-03-01

    Full Text Available Magnetic helical micro- and nanorobots can perform 3D navigation in various liquids with a sub-micrometer precision under low-strength rotating magnetic fields (<10 mT. Since magnetic fields with low strengths are harmless to cells and tissues, magnetic helical micro/nanorobots are promising tools for biomedical applications, such as minimally invasive surgery, cell manipulation and analysis, and targeted therapy. This review provides general information on magnetic helical micro/nanorobots, including their fabrication, motion control, and further functionalization for biomedical applications.

  14. Surface-Chemistry-Mediated Control of Individual Magnetic Helical Microswimmers in a Swarm.

    Science.gov (United States)

    Wang, Xiaopu; Hu, Chengzhi; Schurz, Lukas; De Marco, Carmela; Chen, Xiangzhong; Pané, Salvador; Nelson, Bradley J

    2018-05-31

    Magnetic helical microswimmers, also known as artificial bacterial flagella (ABFs), perform 3D navigation in various liquids under low-strength rotating magnetic fields by converting rotational motion to translational motion. ABFs have been widely studied as carriers for targeted delivery and release of drugs and cells. For in vivo/ in vitro therapeutic applications, control over individual groups of swimmers within a swarm is necessary for several biomedical applications such as drug delivery or small-scale surgery. In this work, we present the selective control of individual swimmers in a swarm of geometrically and magnetically identical ABFs by modifying their surface chemistry. We confirm experimentally and analytically that the forward/rotational velocity ratio of ABFs is independent of their surface coatings when the swimmers are operated below their step-out frequency (the frequency requiring the entire available magnetic torque to maintain synchronous rotation). We also show that ABFs with hydrophobic surfaces exhibit larger step-out frequencies and higher maximum forward velocities compared to their hydrophilic counterparts. Thus, selective control of a group of swimmers within a swarm of ABFs can be achieved by operating the selected ABFs at a frequency that is below their step-out frequencies but higher than the step-out frequencies of unselected ABFs. The feasibility of this method is investigated in water and in biologically relevant solutions. Selective control is also demonstrated inside a Y-shaped microfluidic channel. Our results present a systematic approach for realizing selective control within a swarm of magnetic helical microswimmers.

  15. Trapped particle confinement studies in L = 2 torsatrons for additional helical coils, radial electric field and finite beta effect

    International Nuclear Information System (INIS)

    Kato, A.; Nakamura, Y.; Wakatani, M.

    1990-07-01

    L = 2 torsatrons are studied to improve the high energy trapped particle confinement with additional l = 1 and/or l = 3 helical coils. The winding laws are selected in two ways. One is to realize 'σ - optimization' by the additional helical coils, but this approach loses magnetic well region. The other selection is to produce or deepen the magnetic well by the additional helical coils. L=3 helical coils are usable to this end. In this case the improvement of the trapped particle confinement depends on magnetic axis position. Radial electric field producing sheared rotational motion is also considered to improve the trapped particle confinement in a standard l = 2 torsatron. By excluding cancellation between E x B and ΔB drift motion occurred for the parabolic potential profiles, all deeply trapped particles can be confined in the central region. Degradation of the trapped particle confinement by the Shafranov shift is mitigated by shifting the magnetic axis inside in the vacuum configuration. (author)

  16. An electromagnetic helical undulator for polarized X-rays

    International Nuclear Information System (INIS)

    Gluskin, E.; Vinokurov, N.; Tcheskidov, V.; Medvedko, A.; Evtushenko, Y.; Kolomogorov, V.; Vobly, P.; Antokhin, E.; Ivanov, P.; Vasserman, I. B.; Trakhtenberg, E. M.; Den Hartog, P. K.; Deriy, B.; Erdmann, M.; Makarov, O.; Moog, E. R.

    1999-01-01

    Linearly and circularly polarized x-rays have been very successfully applied to the study of the properties of materials. Many applications can benefit from the availability of energy-turnable, high-brilliance x-ray beams with adjustable polarization properties. A helical undulator that can generate beams of variable (linear to circular) polarization has been designed and built by the Budker Institute of Nuclear Physics and the Advanced Photon Source. The first harmonic of this 12.8-cm-period device will cover the energy range from 0.4 keV to 3.5 keV. An important feature of this fully electromagnetic device is that it will allow one to generate 100% horizontally (K x =O)or vertically (K y =O) plane-polarized radiation, which will enable many experiments otherwise not technically feasible. With symmetric deflection parameters (K x =K y ), the on-axis radiation will be circularly polarized, with a user-selectable handedness. The polarization can be changed at rates up to 10 Hz

  17. Virtual endoscopy post-processing of helical CT data sets

    International Nuclear Information System (INIS)

    Dessl, A.; Giacomuzzi, S.M.; Springer, P.; Stoeger, A.; Pototschnig, C.; Voelklein, C.; Schreder, S.G.; Jaschke, W.

    1997-01-01

    Purpose: The purpose of this work was to test a newly developed, post-processing software for virtual CT endoscopic methods. Virtual endoscopic images were generated from helical CT data sets in the region of the shoulder joint (n=2), the tracheobronchial system (n=3), the nasal sinuses (n=2), the colon (n=2), and the common carotid artery (n=1). Software developed specifically for virtual endoscopy ('Navigator') was used which, after a previous threshold value selection, makes the reconstruction of internal body surfaces possible by an automatic segmentation process. We have evaluated the usage of the software, the reconstruction time for individual images and sequences of images as well as the quality of the reconstruction. All pathological findings of the virtual endoscopy were confirmed by surgery. Results: The post-processing program is easy to use and provides virtual endoscopic images within 50 seconds. Depending of the extent of the data set, virtual tracheobronchoscopy as a cine loop sequence required about 15 minutes. Thorugh use of the threshold value-dependent surface reconstruction the demands on the computer configuration are limited; however, this also created quality problems in image calculation as a consequence of the accompanying loss of data. Conclusions: The Navigator software enables the calculation of virtual endoscopic models with only moderate demands on the hardware. (orig.) [de

  18. An experimental study for qualitatively diagnosing stapes lesions by helical 3-dimensional CT

    International Nuclear Information System (INIS)

    Kawaue, Akifumi; Kuki, Kiyonori; Yamanaka, Noboru; Nishimura, Michihiko

    2001-01-01

    To evaluate qualitative diagnosis of stapes lesions by 3-dimensional computed tomography (3D-CT) combined with superselective image processing (3D-SS) of stapes, we studied helical 3D-CT on a phantom model of the temporal bone. Two stapes models were used-1 made from the bone filler, Celatite, consistent in bone density but changing in cross sectional area, and the other made from an apacerum rod used in quantitative computed tomography (QCT), consistent in cross sectional area but changing in bone density. These stapes models were put into a skull phantom and analyzed by helical 3D-CT. The influence of the tympanic cavity conditions on CT images of stapes was evaluated by filling the phantom model with Vaseline following 3D selective reconstruction. In all stapes models, lowering the lower CT window width threshold resulted in an enlarged cross-sectional area of the model. The higher the bone density, the lower the increase in cross-sectional area in the image. The stapes model with lower density had greater influence on the imaging by tympanic cavity conditions and was likely to be misdiagnosed as showing higher bone density. Based on the experimental study, 3D-SS by helical 3D-CT appears to be a useful measure for qualitatively diagnosing stapes lesions. (author)

  19. Stabilized helical peptides: overview of the technologies and its impact on drug discovery.

    Science.gov (United States)

    Klein, Mark

    2017-11-01

    Protein-protein interactions are predominant in the workings of all cells. Until now, there have been a few successes in targeting protein-protein interactions with small molecules. Peptides may overcome some of the challenges of small molecules in disrupting protein-protein interactions. However, peptides present a new set of challenges in drug discovery. Thus, the study of the stabilization of helical peptides has been extensive. Areas covered: Several technological approaches to helical peptide stabilization have been studied. In this review, stapled peptides, foldamers, and hydrogen bond surrogates are discussed. Issues regarding design principles are also discussed. Furthermore, this review introduces select computational techniques used to aid peptide design and discusses clinical trials of peptides in a more advanced stage of development. Expert opinion: Stabilized helical peptides hold great promise in a wide array of diseases. However, the field is still relatively new and new design principles are emerging. The possibilities of peptide modification are quite extensive and expanding, so the design of stabilized peptides requires great attention to detail in order to avoid a large number of failed lead peptides. The start of clinical trials with stapled peptides is a promising sign for the future.

  20. Evaluation of coronary artery disease by helical CT using retrospective ECG-gating

    International Nuclear Information System (INIS)

    Kawawa, Yoko

    2001-01-01

    The purpose of this study is to evaluate the usefulness of helical CT using retrospective ECG-gating for visualization of the coronary artery and detection of coronary artery disease. We performed a coronary artery phantom study and established this new application, with 1-mm collimation, 1-mm table increment, and 0.1-mm reconstruction (0.8 sec/rotation). Helical CT of 31 patients with 39 coronary artery diseases (34 coronary artery stenoses, 1 vasospastic angina, 1 coronary artery dissection, 1 coronary artery ectasia and 2 coronary artery aneurysms) was performed in a single breath hold and ECG-gating without and with intravenous injection of nonionic iodine contrast material. We selected the images which were not affected by cardiac motion from the reconstruction images, in order to visualize the coronary artery for detection of coronary artery disease. The coronary artery was well visualized in 32 out of 39 vessels (82%). A good visualization of the coronary artery was correlated with the heart rate. Further, in this well visualized group, coronary artery diseases were detected in 24 out of 31 cases (77%). One case of vasospastic angina was not included. It was difficult to detect coronary artery disease in cases of heavily calcified vessels or in the left circumflex artery. Helical CT using this retrospective ECG-gating is a useful noninvasive examination for evaluation of coronary artery disease. (author)

  1. Non-inductive current drive via helicity injection by Alfven waves in low aspects ratio Tokamak

    International Nuclear Information System (INIS)

    Cuperman, S.; Bruma, C.; Komoshvili, K.

    1996-01-01

    A theoretical investigation of radio frequency (RF) current drive via helicity injection in low aspect ratio tokamaks was carried out. A current-carrying cylindrical plasma surrounded by a helical sheet-current antenna and situated inside a perfectly conducting shell was considered. Toroidal features of low aspect ratio tokamaks were simulated by incorporation of the following effects: (i) arbitrarily small aspect ratio, R o /a ≡ 1/ε (ii) strongly sheared equilibrium magnetic field; and (iii) relatively large poloidal component of the equilibrium magnetic field. The study concentrates on the Alfven continuum, i.e. the case in which the wave frequency satisfies the condition {ω Alf (r)} min ≤ω≥{ω Alf (r)} max , where ω Alf (r)≡ω[n(r),B o (o)] is an eigenfrequency of the shear Alfven wave (SAW). Thus, using low-p, ideal magneto-hydrodynamics, the wave equation with correct boundary (matching) conditions was solved, the RF field components were found and subsequently, current drive , power deposition and efficiency were computed. The results of our investigation clearly demonstrate the possibility of generation of RF-driven currents via helicity injection by Alfven waves in low aspect ratio tokamaks, in the SAW mode. A special algorithm was developed which enables the selection of the antenna parameters providing optimal current drive efficiency. (authors)

  2. Buckwheat trypsin inhibitor with helical hairpin structure belongs to a new family of plant defence peptides.

    Science.gov (United States)

    Oparin, Peter B; Mineev, Konstantin S; Dunaevsky, Yakov E; Arseniev, Alexander S; Belozersky, Mikhail A; Grishin, Eugene V; Egorov, Tsezi A; Vassilevski, Alexander A

    2012-08-15

    A new peptide trypsin inhibitor named BWI-2c was obtained from buckwheat (Fagopyrum esculentum) seeds by sequential affinity, ion exchange and reversed-phase chromatography. The peptide was sequenced and found to contain 41 amino acid residues, with four cysteine residues involved in two intramolecular disulfide bonds. Recombinant BWI-2c identical to the natural peptide was produced in Escherichia coli in a form of a cleavable fusion with thioredoxin. The 3D (three-dimensional) structure of the peptide in solution was determined by NMR spectroscopy, revealing two antiparallel α-helices stapled by disulfide bonds. Together with VhTI, a trypsin inhibitor from veronica (Veronica hederifolia), BWI-2c represents a new family of protease inhibitors with an unusual α-helical hairpin fold. The linker sequence between the helices represents the so-called trypsin inhibitory loop responsible for direct binding to the active site of the enzyme that cleaves BWI-2c at the functionally important residue Arg(19). The inhibition constant was determined for BWI-2c against trypsin (1.7×10(-1)0 M), and the peptide was tested on other enzymes, including those from various insect digestive systems, revealing high selectivity to trypsin-like proteases. Structural similarity shared by BWI-2c, VhTI and several other plant defence peptides leads to the acknowledgement of a new widespread family of plant peptides termed α-hairpinins.

  3. Design study of a normal conducting helical snake for AGS

    CERN Document Server

    Takano, Junpei; Okamura, Masahiro; Roser, Thomas; MacKay, William W; Luccio, Alfredo U; Takano, Koji

    2004-01-01

    A new normal conducting snake magnet is being fabricated for the Alternate Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL). In the Relativistic Heavy Ion Collider (RHIC) project, a superconducting type helical dipole magnets had been developed and it performed successfully in high-energy polarized proton acceleration. The new AGS helical snake has the same basic magnetic structure but is more complicated. To achieve no beam shift and no beam deflection in one magnetic device, helical pitches and rotating angles were carefully calculated. Compared to a superconducting magnet, a normal warm magnet must have a large cross- sectional area of conductors which make it difficult to design a magnet with large helical pitch. We developed a modified window frame structure to accommodate the large number of conductors. Its three dimensional magnetic field was simulated by using OPERA3D/TOSCA. 3 Refs.

  4. A 3D printed helical antenna with integrated lens

    KAUST Repository

    Farooqui, Muhammad Fahad; Shamim, Atif

    2015-01-01

    A novel antenna configuration comprising a helical antenna with an integrated lens is demonstrated in this work. The antenna is manufactured by a unique combination of 3D printing of plastic material (ABS) and inkjet printing of silver nano

  5. Particle orbit analysis for LHD helical axis configurations

    International Nuclear Information System (INIS)

    Guasp, J.; Yamazaki, K.; Motojima, O.

    1993-04-01

    Fast ion orbits for helical magnetic axis configurations in LHD (Large Helical Device) are analyzed and compared with the standard circular axis case. Boundaries between passing and helically trapped particle regions show clear differences: in the non-planar axis case the helically trapped region spreads, near the magnetic axis, over a much wider band across the 90deg pitch angle value and shows a very marked asymmetry. The locally trapped particle region is also wider than in the standard case. The differences in the loss cone boundaries of the two cases are rather small, however, the effects of re-entering criteria are very important in both cases. On the contrary, effects of finite coil size are not significant. (author)

  6. Metallic and 3D-printed dielectric helical terahertz waveguides.

    Science.gov (United States)

    Vogt, Dominik Walter; Anthony, Jessienta; Leonhardt, Rainer

    2015-12-28

    We investigate guidance of Terahertz (THz) radiation in metallic and 3D-printed dielectric helical waveguides in the frequency range from 0.2 to 1 THz. Our experimental results obtained from THz time-domain spectroscopy (THz-TDS) measurements are in very good agreement with finite-difference time-domain (FDTD) simulations. We observe single-mode, low loss and low dispersive propagation of THz radiation in metallic helical waveguides over a broad bandwidth. The 3D-printed dielectric helical waveguides have substantially extended the bandwidth of a low loss dielectric tube waveguide as observed from the experimental and simulation results. The high flexibility of the helical design allows an easy incorporation into bench top THz devices.

  7. Helical-axis stellarators with noninterlocking planar coils

    International Nuclear Information System (INIS)

    Reiman, A.; Boozer, A.

    1983-08-01

    The properties of helical axis stellarator fields generated by unlinked, planar coils are described. It is shown that such fields can have a magnetic well and large rotational transform, implying large equilibrium and stability beta limits

  8. Helical-axis stellarators with noninterlocking planar coils

    Energy Technology Data Exchange (ETDEWEB)

    Reiman, A.; Boozer, A.

    1983-08-01

    The properties of helical axis stellarator fields generated by unlinked, planar coils are described. It is shown that such fields can have a magnetic well and large rotational transform, implying large equilibrium and stability beta limits.

  9. Energy and helicity of magnetic torus knots and braids

    Science.gov (United States)

    Oberti, Chiara; Ricca, Renzo L.

    2018-02-01

    By considering steady magnetic fields in the shape of torus knots and unknots in ideal magnetohydrodynamics, we compute some fundamental geometric and physical properties to provide estimates for magnetic energy and helicity. By making use of an appropriate parametrization, we show that knots with dominant toroidal coils that are a good model for solar coronal loops have negligible total torsion contribution to magnetic helicity while writhing number provides a good proxy. Hence, by the algebraic definition of writhe based on crossing numbers, we show that the estimated values of writhe based on image analysis provide reliable information for the exact values of helicity. We also show that magnetic energy is linearly related to helicity, and the effect of the confinement of magnetic field can be expressed in terms of geometric information. These results can find useful application in solar and plasma physics, where braided structures are often present.

  10. Investigation into the heat transfer performance of helically ribbed surfaces

    International Nuclear Information System (INIS)

    Firth, R.J.

    1981-12-01

    The first part of an investigation into flow and heat transfer in annular channels and seven pin clusters is described. One of the main aims of the project is to improve cluster heat transfer prediction codes for helically ribbed surfaces. A study is made of the heat transfer and flow characteristics of a helically ribbed pin in an annular channel. It is shown that the swirling flow, which is induced by the helical ribs, gives rise to substantially enhanced diffusivity levels. This phenomenon had not been taken into account by previous analysis techniques. The methods for analysing heat transfer and pressure drop data from annular channels which were originally developed for non-swirling flow are generalised to accommodate swirling flow. The new methods are shown to be consistent with empirical data. Roughness parameter data is presented for helically ribbed surfaces with an axial rib pitch into height ratio of about 7. (author)

  11. Interaction of 18-residue peptides derived from amphipathic helical ...

    Indian Academy of Sciences (India)

    Madhsudhan

    interaction of proteins and peptides with membranes (Segrest ... favour surface activity have been described by Eisenberg et ... amphipathicity and propensity for α-helical conformation ..... Membrane destabilisation occurs due to electrostatic.

  12. Energy fluxes in helical magnetohydrodynamics and dynamo action

    Indian Academy of Sciences (India)

    Kinetic and magnetic helicities do not affect the renormalized parameters, ... Generation of magnetic field in plasma, usually referred to as 'dynamo', is one of the ..... energy fluxes for the inertial-range wave numbers where the same power.

  13. Electrical resistivity and dielectric properties of helical microorganism cells coated with silver by electroless plating

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Jun, E-mail: jun_cai@buaa.edu.cn [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Lan, Mingming; Zhang, Deyuan; Zhang, Wenqiang [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer We use the microorganism cells as forming templates to fabricate the bio-based conductive particles. Black-Right-Pointing-Pointer The microorganism cells selected as forming templates are Spirulina platens, which are of natural helical shape and high aspect ratio. Black-Right-Pointing-Pointer The sliver-coated Spirulina cells are a kind of lightweight conductive particles. Black-Right-Pointing-Pointer The composites containing sliver-coated Spirulina cells exhibit a lower percolation value. - Abstract: In this paper, microorganism cells (Spirulina platens) were used as forming templates for the fabrication of the helical functional particles by electroless silver plating process. The morphologies and ingredients of the coated Spirulina cells were analyzed with scanning electron microscopy and energy dispersive spectrometer. The crystal structures were characterized by employing the X-ray diffraction. The electrical resistivity and dielectric properties of samples containing different volume faction of sliver-coated Spirulina cells were measured and investigated by four-probe meter and vector network analyzer. The results showed that the Spirulina cells were successfully coated with a uniform silver coating and their initial helical shapes were perfectly kept. The electrical resistivity and dielectric properties of the samples had a strong dependence on the volume content of sliver-coated Spirulina cells and the samples could achieve a low percolation value owing to high aspect ratio and preferable helical shape of Spirulina cells. Furthermore, the conductive mechanism was analyzed with the classic percolation theory, and the values of {phi}{sub c} and t were obtained.

  14. Acute pulmonary embolism in helical computed tomography

    International Nuclear Information System (INIS)

    Paslawski, M.

    2005-01-01

    Pulmonary embolism is a common condition in which diagnostic and therapeutic delays contribute to substantial morbidity and mortality. Clinical diagnosis is difficult because the signs and symptoms re unspecific, and a differential diagnosis is extensive, including pneumonia or bronchitis, asthma, myocardial infraction, pulmonary edema, anxiety, dissection of the aorta, pericardial tamponade, lung cancer, primary pulmonary hypertension, rib fracture, and pneumothorax. The purpose of the study was to present the use of CT in diagnosing acute pulmonary embolism. A group of 23 patients with clinically suspected pulmonary embolism underwent CT examination with a helical CT scanner (Somatom Emotion, Siemens) before and after administration of 150 ml of Ultravist. Pulmonary embolism was found in the CT examinations of 13 patients. In two of these it was a central filling defect. Amputation of the artery was found in one. Parietal filling defect in three patients formed an acute angle with the vessel walls. Saddle emboli appearing as filling defects in the contrast column that hung over vessel bifurcations was found in two patients. In five patients,emboli were found in small segmental arteries. CT provides information not only on the pulmonary arteries, but also on the lung parenchyma, hila, mediastinum, and the heart. Alternative findings may be identified by CT chest examination, stablishing alternative diagnoses, including pulmonary disorders (such as pneumonia or fibrosis), pleural abnormalities, and cardiovascular disease (such as aortic dissection or pericardial tamponade). Another advantage of the CT is its widespread availability.(author)

  15. Polymer dynamics driven by a helical filament

    Science.gov (United States)

    Balin, Andrew; Shendruk, Tyler; Zoettl, Andreas; Yeomans, Julia

    Microbial flagellates typically inhabit complex suspensions of extracellular polymeric material which can impact the swimming speed of motile microbes, filter-feeding of sessile cells, and the generation of biofilms. There is currently a need to better understand how the fundamental dynamics of polymers near active cells or flagella impacts these various phenomena. We study the hydrodynamic and steric influence of a rotating helical filament on suspended polymers using Stokesian Dynamics simulations. Our results show that as a stationary rotating helix pumps fluid along its long axis, nearby polymers migrate radially inwards and are elongated in the process. We observe that the actuation of the helix tends to increase the probability of finding polymeric material within its pervaded volume. At larger Weissenberg numbers, this accumulation of polymers within the vicinity of the helix is greater. Further, we have analysed the stochastic work performed by the helix on the polymers and we show that this quantity is positive on average and increases with polymer contour length. Our results provide a basis for understanding the microscopic interactions that govern cell dynamics in complex media. This work was supported through funding from the ERC Advanced Grant 291234 MiCE and we acknowledge EMBO funding to TNS (ALTF181-2013).

  16. Electronic Band Structure of Helical Polyisocyanides.

    Science.gov (United States)

    Champagne, Benoît; Liégeois, Vincent; Fripiat, Joseph G; Harris, Frank E

    2017-10-19

    Restricted Hartree-Fock computations are reported for a methyl isocyanide polymer (repeating unit -C═N-CH 3 ), whose most stable conformation is expected to be a helical chain. The computations used a standard contracted Gaussian orbital set at the computational levels STO-3G, 3-21G, 6-31G, and 6-31G**, and studies were made for two line-group configurations motivated by earlier work and by studies of space-filling molecular models: (1) A structure of line-group symmetry L9 5 , containing a 9-fold screw axis with atoms displaced in the axial direction by 5/9 times the lattice constant, and (2) a structure of symmetry L4 1 that had been proposed, containing a 4-fold screw axis with translation by 1/4 of the lattice constant. Full use of the line-group symmetry was employed to cause most of the computational complexity to depend only on the size of the asymmetric repeating unit. Data reported include computed bond properties, atomic charge distribution, longitudinal polarizability, band structure, and the convoluted density of states. Most features of the description were found to be insensitive to the level of computational approximation. The work also illustrates the importance of exploiting line-group symmetry to extend the range of polymer structural problems that can be treated computationally.

  17. Pulmonary artery aneurysm in Bechcet's disease: helical computed tomography study

    International Nuclear Information System (INIS)

    Munoz, J.; Caballero, P.; Olivera, M. J.; Cajal, M. L.; Caniego, J. L.

    2000-01-01

    Behcet's disease is a vasculitis of unknown etiology that affects arteries and veins of different sizes and can be associated with pulmonary artery aneurysms. We report the case of a patient with Behcet's disease and a pulmonary artery aneurysm who was studied by means of plain chest X ray, helical computed tomography and pulmonary arteriography. Helical computed tomography is a reliable technique for the diagnosis and follow-up of these patients. (Author) 9 refs

  18. ADDITIVE SELF-HELICITY AS A KINK MODE THRESHOLD

    International Nuclear Information System (INIS)

    Malanushenko, A.; Longcope, D. W.; Fan, Y.; Gibson, S. E.

    2009-01-01

    In this paper, we propose that additive self-helicity, introduced by Longcope and Malanushenko, plays a role in the kink instability for complex equilibria, similar to twist helicity for thin flux tubes. We support this hypothesis by a calculation of additive self-helicity of a twisted flux tube from the simulation of Fan and Gibson. As more twist gets introduced, the additive self-helicity increases, and the kink instability of the tube coincides with the drop of additive self-helicity, after the latter reaches the value of H A /Φ 2 ∼ 1.5 (where Φ is the flux of the tube and H A is the additive self-helicity). We compare the additive self-helicity to twist for a thin subportion of the tube to illustrate that H A /Φ 2 is equal to the twist number, studied by Berger and Field, when the thin flux tube approximation is applicable. We suggest that the quantity H A /Φ 2 could be treated as a generalization of a twist number, when the thin flux tube approximation is not applicable. A threshold on a generalized twist number might prove extremely useful studying complex equilibria, just as the twist number itself has proven useful studying idealized thin flux tubes. We explicitly describe a numerical method for calculating additive self-helicity, which includes an algorithm for identifying a domain occupied by a flux bundle and a method of calculating potential magnetic field confined to this domain. We also describe a numerical method to calculate twist of a thin flux tube, using a frame parallelly transported along the axis of the tube.

  19. Design windows and cost analysis on helical reactors

    International Nuclear Information System (INIS)

    Kozaki, Y.; Imagawa, S.; Sagara, A.

    2007-01-01

    The LHD type helical reactors are characterized by a large major radius but slender helical coil, which give us different approaches for power plants from tokamak reactors. For searching design windows of helical reactors and discussing their potential as power plants, we have developed a mass-cost estimating model linked with system design code (HeliCos), thorough studying the relationships between major plasma parameters and reactor parameters, and weight of major components. In regard to cost data we have much experience through preparing ITER construction. To compare the weight and cost of magnet systems between tokamak and helical reactors, we broke down magnet systems and cost factors, such as weights of super conducting strands, conduits, support structures, and winding unit costs, through estimating ITER cost data basis. Based on FFHR2m1 deign we considered a typical 3 GWth helical plant (LHD type) with the same magnet size, coil major radius Rc 14 m, magnetic energy 120 GJ, but increasing plasma densities. We evaluated the weight and cost of magnet systems of 3 GWth helical plant, the total magnet weights of 16,000ton and costs of 210 BYen, which are similar values of tokamak reactors (10,200 ton, 110 BYen in ITER 2002 report, and 21,900 ton, 275 BYen in ITER FDR1999). The costs of strands and winding occupy 70% of total magnet costs, and influence entire power plants economics. The design windows analysis and comparative economics studies to optimize the main reactor parameters have been carried out. Economics studies show that it is misunderstanding to consider helical coils are too large and too expensive to achieve power plants. But we should notice that the helical reactor design windows and economics are very sensitive to allowable blanket space (depend on ergodic layer conditions) and diverter configuration for decreasing heat loads. (orig.)

  20. Tokamak startup using point-source dc helicity injection.

    Science.gov (United States)

    Battaglia, D J; Bongard, M W; Fonck, R J; Redd, A J; Sontag, A C

    2009-06-05

    Startup of a 0.1 MA tokamak plasma is demonstrated on the ultralow aspect ratio Pegasus Toroidal Experiment using three localized, high-current density sources mounted near the outboard midplane. The injected open field current relaxes via helicity-conserving magnetic turbulence into a tokamaklike magnetic topology where the maximum sustained plasma current is determined by helicity balance and the requirements for magnetic relaxation.

  1. Comparison between helical computed tomography angiography and intraoperative findings

    Directory of Open Access Journals (Sweden)

    Abijit Shetty

    2014-01-01

    Conclusions: Helical CT is important in delineating the arterial, venous, and ureteral anatomy and can show the important incidental findings. Left renal donors and males have more variations in their renal anatomy. Technically challenging laparoscopic nephrectomy on the multiple-vessel-side donor is possible with the aid of helical CT. The importance of the CT in evaluating donor renal anatomy for a technically challenging laparoscopic donor nephrectomy is commendable.

  2. Scale Dependence of Magnetic Helicity in the Solar Wind

    Science.gov (United States)

    Brandenburg, Axel; Subramanian, Kandaswamy; Balogh, Andre; Goldstein, Melvyn L.

    2011-01-01

    We determine the magnetic helicity, along with the magnetic energy, at high latitudes using data from the Ulysses mission. The data set spans the time period from 1993 to 1996. The basic assumption of the analysis is that the solar wind is homogeneous. Because the solar wind speed is high, we follow the approach first pioneered by Matthaeus et al. by which, under the assumption of spatial homogeneity, one can use Fourier transforms of the magnetic field time series to construct one-dimensional spectra of the magnetic energy and magnetic helicity under the assumption that the Taylor frozen-in-flow hypothesis is valid. That is a well-satisfied assumption for the data used in this study. The magnetic helicity derives from the skew-symmetric terms of the three-dimensional magnetic correlation tensor, while the symmetric terms of the tensor are used to determine the magnetic energy spectrum. Our results show a sign change of magnetic helicity at wavenumber k approximately equal to 2AU(sup -1) (or frequency nu approximately equal to 2 microHz) at distances below 2.8AU and at k approximately equal to 30AU(sup -1) (or nu approximately equal to 25 microHz) at larger distances. At small scales the magnetic helicity is positive at northern heliographic latitudes and negative at southern latitudes. The positive magnetic helicity at small scales is argued to be the result of turbulent diffusion reversing the sign relative to what is seen at small scales at the solar surface. Furthermore, the magnetic helicity declines toward solar minimum in 1996. The magnetic helicity flux integrated separately over one hemisphere amounts to about 10(sup 45) Mx(sup 2) cycle(sup -1) at large scales and to a three times lower value at smaller scales.

  3. Concept and development of measurement method of time sensitivity profile (TSP) in X-ray CT. Comparison of non-helical, single-slice helical, and multi-slice helical scans

    International Nuclear Information System (INIS)

    Tsujioka, Katsumi; Ida, Yoshihiro; Ohtsubo, Hironori; Takahashi, Yasukata; Niwa, Masayoshi

    2000-01-01

    We focused on the time element contained in a single CT image, and devised the concept of a time-sensitivity profile (TSP) describing how the time element is translated into an image. We calculated the data collection time range when the helical pitch is changed in non helical scans, single slice helical scans, and multi slice helical scans. We then calculated the time sensitivity profile (TSP) from the weighting applied when the data collection time range is translated into an image. TSP was also measured for each scanning method using our self-made moving phantom. TSPs obtained from the calculation and the experiments were very close. TSP showed interesting characteristics with each scanning method, especially in the case of multi slice helical scanning, in which TSP became shorter as helical pitch increased. We referred to the TSP's FWHM as the effective scanning time. When we conducted multi slice helical scanning at helical pitch 3, the effective scanning time increased to about 24% longer than that of a non helical scan. When we conducted multi slice helical scanning at helical pitch 5 or 6, the effective scanning time was about half that of a non helical scan. The time sensitivity profile (TSP) is a totally new concept that we consider an important element in discussing the time resolution of a CT scanner. The results of this review will provide significant data in determining the scanning parameters when scanning a moving object. (author)

  4. Feasibility study of helical tomotherapy for total body or total marrow irradiation

    International Nuclear Information System (INIS)

    Hui, Susanta K.; Kapatoes, Jeff; Fowler, Jack; Henderson, Douglas; Olivera, Gustavo; Manon, Rafael R.; Gerbi, Bruce; Mackie, T. R.; Welsh, James S.

    2005-01-01

    Total body radiation (TBI) has been used for many years as a preconditioning agent before bone marrow transplantation. Many side effects still plague its use. We investigated the planning and delivery of total body irradiation (TBI) and selective total marrow irradiation (TMI) and a reduced radiation dose to sensitive structures using image-guided helical tomotherapy. To assess the feasibility of using helical tomotherapy (A) we studied variations in pitch, field width, and modulation factor on total body and total marrow helical tomotherapy treatments. We varied these parameters to provide a uniform dose along with a treatment times similar to conventional TBI (15-30 min). (B) We also investigated limited (head, chest, and pelvis) megavoltage CT (MVCT) scanning for the dimensional pretreatment setup verification rather than total body MVCT scanning to shorten the overall treatment time per treatment fraction. (C) We placed thermoluminescent detectors (TLDs) inside a Rando phantom to measure the dose at seven anatomical sites, including the lungs. A simulated TBI treatment showed homogeneous dose coverage (±10%) to the whole body. Doses to the sensitive organs were reduced by 35%-70% of the target dose. TLD measurements on Rando showed an accurate dose delivery (±7%) to the target and critical organs. In the TMI study, the dose was delivered conformally to the bone marrow only. The TBI and TMI treatment delivery time was reduced (by 50%) by increasing the field width from 2.5 to 5.0 cm in the inferior-superior direction. A limited MVCT reduced the target localization time 60% compared to whole body MVCT. MVCT image-guided helical tomotherapy offers a novel method to deliver a precise, homogeneous radiation dose to the whole body target while reducing the dose significantly to all critical organs. A judicious selection of pitch, modulation factor, and field size is required to produce a homogeneous dose distribution along with an acceptable treatment time. In

  5. Phonological reduplication in sign language: rules rule

    Directory of Open Access Journals (Sweden)

    Iris eBerent

    2014-06-01

    Full Text Available Productivity—the hallmark of linguistic competence—is typically attributed to algebraic rules that support broad generalizations. Past research on spoken language has documented such generalizations in both adults and infants. But whether algebraic rules form part of the linguistic competence of signers remains unknown. To address this question, here we gauge the generalization afforded by American Sign Language (ASL. As a case study, we examine reduplication (X→XX—a rule that, inter alia, generates ASL nouns from verbs. If signers encode this rule, then they should freely extend it to novel syllables, including ones with features that are unattested in ASL. And since reduplicated disyllables are preferred in ASL, such rule should favor novel reduplicated signs. Novel reduplicated signs should thus be preferred to nonreduplicative controls (in rating, and consequently, such stimuli should also be harder to classify as nonsigns (in the lexical decision task. The results of four experiments support this prediction. These findings suggest that the phonological knowledge of signers includes powerful algebraic rules. The convergence between these conclusions and previous evidence for phonological rules in spoken language suggests that the architecture of the phonological mind is partly amodal.

  6. A Better Budget Rule

    Science.gov (United States)

    Dothan, Michael; Thompson, Fred

    2009-01-01

    Debt limits, interest coverage ratios, one-off balanced budget requirements, pay-as-you-go rules, and tax and expenditure limits are among the most important fiscal rules for constraining intertemporal transfers. There is considerable evidence that the least costly and most effective of such rules are those that focus directly on the rate of…

  7. Helical Birods: An Elastic Model of Helically Wound Double-Stranded Rods

    KAUST Repository

    Prior, Christopher

    2014-03-11

    © 2014, Springer Science+Business Media Dordrecht. We consider a geometrically accurate model for a helically wound rope constructed from two intertwined elastic rods. The line of contact has an arbitrary smooth shape which is obtained under the action of an arbitrary set of applied forces and moments. We discuss the general form the theory should take along with an insight into the necessary geometric or constitutive laws which must be detailed in order for the system to be complete. This includes a number of contact laws for the interaction of the two rods, in order to fit various relevant physical scenarios. This discussion also extends to the boundary and how this composite system can be acted upon by a single moment and force pair. A second strand of inquiry concerns the linear response of an initially helical rope to an arbitrary set of forces and moments. In particular we show that if the rope has the dimensions assumed of a rod in the Kirchhoff rod theory then it can be accurately treated as an isotropic inextensible elastic rod. An important consideration in this demonstration is the possible effect of varying the geometric boundary constraints; it is shown the effect of this choice becomes negligible in this limit in which the rope has dimensions similar to those of a Kirchhoff rod. Finally we derive the bending and twisting coefficients of this effective rod.

  8. Recent Results of Helical Nonneutral Plasmas on Compact Helical System (CHS)

    International Nuclear Information System (INIS)

    Himura, H.; Yamamoto, Y.; Sanpei, A.; Masamune, S.; Wakabayashi, H.; Isobe, M.

    2006-01-01

    First of all, non-constant space potential φs and electron density ne on magnetic surfaces of helical nonneutral plasmas are verified experimentally. The difference in φs enlarges significantly at the outer region inside the closed magnetic surfaces, and the corresponding equipotential surfaces are inferred to shift upward vertically with respect to magnetic surfaces. Meanwhile, larger value of ne is clearly observed in the downward region (z < 0) of magnetic surfaces, which seems to be consistent with the φs measurement. These results are the first evidence which strongly suggests the equilibrium proposed for nonneutral plasmas confined in closed magnetic surfaces. Secondly, in order to investigate the mechanism of the multiple disruption of helical nonneutral plasmas observed in experiments, space and time evolutions of electron flux are measured carefully inside the magnetic surfaces, when the plasma disruption occurs. Surprisingly, a set of data show that the observed disruption is at first happened at ρ ∼ 0.8, where ρ is the normalized minor radius, and then, it seems to propagate inside magnetic surfaces

  9. Markov analysis of alpha-helical, beta-sheet and random coil regions of proteins

    International Nuclear Information System (INIS)

    Macchiato, M.; Tramontano, A.

    1983-01-01

    The rules up to now used to predict the spatial configuration of proteins from their primary structure are mostly based on the recurrence analysis of some doublets, triplets and so on of contiguous amino acids, but they do not take into account the correlation characteristics of the whole amino acid sequence. A statistical analysis of amino acid sequences for the alpha-helical, beta-sheet and random coil regions of about twenty proteins with known secondary structure by considering correlations effects has been carried out. The obtained results demonstrate that these sequences are at least a second-order Markov chain, i.e. they appear as if they were generated by a source that remembers at least the two aminoacids before the one being generated and that these two previous symbols influence the present choice

  10. Electrohydrodynamic (EHD) vortices in helical turbulence

    International Nuclear Information System (INIS)

    Kikuchi, H.

    1996-01-01

    The study of large-scale coherent hydrodynamic (HD) vortex generation has been extended to electrified charged dusty vortices to be termed as electrohydrodynamic (EHD) vortices, incorporating helical turbulence in electric and magnetic fields into that in fluid velocity, which are all created by an external DC electric field on the background. A new equation of EHD vortices is introduced on the basis of a set of EHD or electromagnetohydrodynamic (EMHD) equations, including equations of state and a full set of Maxwell's equations by using functional techniques for estimating equations for an ensemble average, turbulent background, and additional random field. In fact, EHD vortices for a charged dusty fluid can be more explosive with larger instabilities than HD vortices. In addition, it is inferred that an external DC electric field could provide the origin of additional self-organization to a coalescence of fluid vortex and electric field lines as a manifestation of a new frozen-in field concept for electric fields when the electric Reynolds number is sufficiently high. This is discussed on the basis of a set of general transport equations for fluid vorticity, magnetic and electric fields that are rederived concisely. In particular, a novel concept of electric field line merging-reconnection is developed in close relation to fluid vortex line merging, indicating a coalescence of fluid vortex breakdown or merging point and electric field line reconnection point, X-type or O-type with possible application to tornadic thunderstorms. In fact, a thundercloud charge distribution so as to provide a coalescence of fluid vortex and electric field lines is quite possible without theoretical inconsistency, and is thought most likely to occur from observations available so far. (orig.)

  11. New Safety rules

    CERN Multimedia

    Safety Commission

    2008-01-01

    The revision of CERN Safety rules is in progress and the following new Safety rules have been issued on 15-04-2008: Safety Procedure SP-R1 Establishing, Updating and Publishing CERN Safety rules: http://cern.ch/safety-rules/SP-R1.htm; Safety Regulation SR-S Smoking at CERN: http://cern.ch/safety-rules/SR-S.htm; Safety Regulation SR-M Mechanical Equipment: http://cern.ch/safety-rules/SR-M.htm; General Safety Instruction GSI-M1 Standard Lifting Equipment: http://cern.ch/safety-rules/GSI-M1.htm; General Safety Instruction GSI-M2 Standard Pressure Equipment: http://cern.ch/safety-rules/GSI-M2.htm; General Safety Instruction GSI-M3 Special Mechanical Equipment: http://cern.ch/safety-rules/GSI-M3.htm. These documents apply to all persons under the Director General’s authority. All Safety rules are available at the web page: http://www.cern.ch/safety-rules The Safety Commission

  12. The mechanical design and validation of the helical tube boilers for Hartlepool and Heysham AGR stations

    International Nuclear Information System (INIS)

    Skinner, V.R.

    1983-01-01

    The 32 helically coiled once-through boiler units at Hartlepool and Heysham represent a major advance in the technologies of boiler design, manufacture and site construction. They are particularly complex in that they incorporate integral reheaters; they employ three different tubing materials and five different structural materials, each with operating temperature limitations; and they must fit compactly into pods in the reactor pressure vessel walls. A general description of the boilers is followed by a review of external factors which influenced the mechanical design and validation programme over 15 years. Against this background selected components are discussed in detail in terms of particular loading conditions and stress analysis. (author)

  13. Action Rules Mining

    CERN Document Server

    Dardzinska, Agnieszka

    2013-01-01

    We are surrounded by data, numerical, categorical and otherwise, which must to be analyzed and processed to convert it into information that instructs, answers or aids understanding and decision making. Data analysts in many disciplines such as business, education or medicine, are frequently asked to analyze new data sets which are often composed of numerous tables possessing different properties. They try to find completely new correlations between attributes and show new possibilities for users.   Action rules mining discusses some of data mining and knowledge discovery principles and then describe representative concepts, methods and algorithms connected with action. The author introduces the formal definition of action rule, notion of a simple association action rule and a representative action rule, the cost of association action rule, and gives a strategy how to construct simple association action rules of a lowest cost. A new approach for generating action rules from datasets with numerical attributes...

  14. In human pseudouridine synthase 1 (hPus1), a C-terminal helical insert blocks tRNA from binding in the same orientation as in the Pus1 bacterial homologue TruA, consistent with their different target selectivities.

    Science.gov (United States)

    Czudnochowski, Nadine; Wang, Amy Liya; Finer-Moore, Janet; Stroud, Robert M

    2013-10-23

    Human pseudouridine (Ψ) synthase Pus1 (hPus1) modifies specific uridine residues in several non-coding RNAs: tRNA, U2 spliceosomal RNA, and steroid receptor activator RNA. We report three structures of the catalytic core domain of hPus1 from two crystal forms, at 1.8Å resolution. The structures are the first of a mammalian Ψ synthase from the set of five Ψ synthase families common to all kingdoms of life. hPus1 adopts a fold similar to bacterial Ψ synthases, with a central antiparallel β-sheet flanked by helices and loops. A flexible hinge at the base of the sheet allows the enzyme to open and close around an electropositive active-site cleft. In one crystal form, a molecule of Mes [2-(N-morpholino)ethane sulfonic acid] mimics the target uridine of an RNA substrate. A positively charged electrostatic surface extends from the active site towards the N-terminus of the catalytic domain, suggesting an extensive binding site specific for target RNAs. Two α-helices C-terminal to the core domain, but unique to hPus1, extend along the back and top of the central β-sheet and form the walls of the RNA binding surface. Docking of tRNA to hPus1 in a productive orientation requires only minor conformational changes to enzyme and tRNA. The docked tRNA is bound by the electropositive surface of the protein employing a completely different binding mode than that seen for the tRNA complex of the Escherichia coli homologue TruA. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. 18 CFR 385.104 - Rule of construction (Rule 104).

    Science.gov (United States)

    2010-04-01

    ... Definitions § 385.104 Rule of construction (Rule 104). To the extent that the text of a rule is inconsistent with its caption, the text of the rule controls. [Order 376, 49 FR 21705, May 23, 1984] ...

  16. Helical Polyacetylenes Induced via Noncovalent Chiral Interactions and Their Applications as Chiral Materials.

    Science.gov (United States)

    Maeda, Katsuhiro; Yashima, Eiji

    2017-08-01

    Construction of predominantly one-handed helical polyacetylenes with a desired helix sense utilizing noncovalent chiral interactions with nonracemic chiral guest compounds based on a supramolecular approach is described. As with the conventional dynamic helical polymers possessing optically active pendant groups covalently bonded to the polymer chains, this noncovalent helicity induction system can show significant chiral amplification phenomena, in which the chiral information of the nonracemic guests can transfer with high cooperativity through noncovalent bonding interactions to induce an almost single-handed helical conformation in the polymer backbone. An intriguing "memory effect" of the induced macromolecular helicity is observed for some polyacetylenes, which means that the helical conformations induced in dynamic helical polyacetylene can be transformed into metastable static ones by tuning their helix-inversion barriers. Potential applications of helical polyacetylenes with controlled helix sense constructed by the "noncovalent helicity induction and/or memory effect" as chiral materials are also described.

  17. Single helically folded aromatic oligoamides that mimic the charge surface of double-stranded B-DNA

    Science.gov (United States)

    Ziach, Krzysztof; Chollet, Céline; Parissi, Vincent; Prabhakaran, Panchami; Marchivie, Mathieu; Corvaglia, Valentina; Bose, Partha Pratim; Laxmi-Reddy, Katta; Godde, Frédéric; Schmitter, Jean-Marie; Chaignepain, Stéphane; Pourquier, Philippe; Huc, Ivan

    2018-05-01

    Numerous essential biomolecular processes require the recognition of DNA surface features by proteins. Molecules mimicking these features could potentially act as decoys and interfere with pharmacologically or therapeutically relevant protein-DNA interactions. Although naturally occurring DNA-mimicking proteins have been described, synthetic tunable molecules that mimic the charge surface of double-stranded DNA are not known. Here, we report the design, synthesis and structural characterization of aromatic oligoamides that fold into single helical conformations and display a double helical array of negatively charged residues in positions that match the phosphate moieties in B-DNA. These molecules were able to inhibit several enzymes possessing non-sequence-selective DNA-binding properties, including topoisomerase 1 and HIV-1 integrase, presumably through specific foldamer-protein interactions, whereas sequence-selective enzymes were not inhibited. Such modular and synthetically accessible DNA mimics provide a versatile platform to design novel inhibitors of protein-DNA interactions.

  18. Helical CT in evaluation of the bronchial tree

    International Nuclear Information System (INIS)

    Perhomaa, M.; Laehde, S.; Rossi, O.; Suramo, I.

    1997-01-01

    Purpose: To establish a protocol for and to assess the value of helical CT in the imaging of the bronchial tree. Material and Methods: Noncontrast helical CT was performed in 30 patients undergoing fiberoptic bronchoscopy for different reasons. Different protocols were compared; they included overlapping 10 mm, 5 mm, or 3 mm slices and non-tilted, cephalad or caudal tilted images. Ordinary cross-sectional and multiplanar 2D reformats were applied for visualization of the bronchial branches. The effect of increasing the helical pitch was tested in one patient. Results: A total of 92.1-100% of the segmental bronchi present in the helical acquisitions were identified by the different protocols. The collimation had no significant impact on the identification of the bronchial branches, but utilization of 3-mm overlapping slices made it easier to distinguish the nearby branches and provided better longitudinal visualization of the bronchi in 2D reformats. The tilted scans illustrated the disadvantage of not covering all segmental bronchi in one breath-hold. An increase of the pitch from 1 to 1.5 did not cause noticeable blurring of the images. CT and bronchoscopic findings correlated well in the area accessible to bronchoscopy, but CT detected 5 additional pathological lesions (including 2 cancers) in the peripheral lung. Conclusion: Helical CT supplemented with bronchography-like 2D reformats provides an effective method complementary to bronchoscopy in the examination of the bronchial tree. (orig.)

  19. Relativistic helicity and link in Minkowski space-time

    International Nuclear Information System (INIS)

    Yoshida, Z.; Kawazura, Y.; Yokoyama, T.

    2014-01-01

    A relativistic helicity has been formulated in the four-dimensional Minkowski space-time. Whereas the relativistic distortion of space-time violates the conservation of the conventional helicity, the newly defined relativistic helicity conserves in a barotropic fluid or plasma, dictating a fundamental topological constraint. The relation between the helicity and the vortex-line topology has been delineated by analyzing the linking number of vortex filaments which are singular differential forms representing the pure states of Banach algebra. While the dimension of space-time is four, vortex filaments link, because vorticities are primarily 2-forms and the corresponding 2-chains link in four dimension; the relativistic helicity measures the linking number of vortex filaments that are proper-time cross-sections of the vorticity 2-chains. A thermodynamic force yields an additional term in the vorticity, by which the vortex filaments on a reference-time plane are no longer pure states. However, the vortex filaments on a proper-time plane remain to be pure states, if the thermodynamic force is exact (barotropic), thus, the linking number of vortex filaments conserves

  20. Chirality of Intermediate Filaments and Magnetic Helicity of Active Regions

    Science.gov (United States)

    Lim, Eun-Kyung; Chae, J.

    2009-05-01

    Filaments that form either between or around active regions (ARs) are called intermediate filaments. Even though there have been many theoretical studies, the origin of the chirality of filaments is still unknown. We investigated how intermediate filaments are related to their associated ARs, especially from the point of view of magnetic helicity and the orientation of polarity inversion lines (PILs). The chirality of filaments has been determined based on the orientations of barbs observed in the full-disk Hα images taken at Big Bear Solar Observatory during the rising phase of solar cycle 23. The sign of magnetic helicity of ARs has been determined using S/inverse-S shaped sigmoids from Yohkoh SXT images. As a result, we have found a good correlation between the chirality of filaments and the magnetic helicity sign of ARs. Among 45 filaments, 42 filaments have shown the same sign as helicity sign of nearby ARs. It has been also confirmed that the role of both the orientation and the relative direction of PILs to ARs in determining the chirality of filaments is not significant, against a theoretical prediction. These results suggest that the chirality of intermediate filaments may originate from magnetic helicity of their associated ARs.

  1. Gynecological applications of helical CT using SmartPrep

    Energy Technology Data Exchange (ETDEWEB)

    Sakurada, Akira; Kakizaki, Dai; Abe, Kimihiko [Tokyo Medical Coll. (Japan)

    1999-11-01

    SmartPrep is software program for scanning a given region of interest (ROI) at optimal contrast density. An operator can arbitrarily define ROI and preset the CT value at which scanning should be started. After the injection of a contrast medium, system conducts continuous monitoring of the ROI and the operator starts helical scanning of the planned region when the present CT value has been reached. In comparison with conventional helical CT that requires a period of time from the beginning of contrast medium injection to the beginning of scanning, SmartPrep minimizes personal error and better depicts the artery-predominant phase under optimal conditions. In this study we examine the usefulness of contrast-enhanced helical CT using SmartPrep in the evaluation of gynecological disease. When the contrast medium was injected into the dorsal vein of the hand at a rate of 3 ml/sec, strong staining of pelvic arteries was observed in the CT images started at 17 to 23 sec after injection. The early-phase helical CT obtained under these conditions provided good depiction of lesions in cases of placenta accreta and invasive mole, as well as clear demonstration of tumor angiogenesis and evaluation of laterality in cases of cervical cancer. Comparison of the early and delayed phase also facilitated easier evaluation of lymph nodes than conventional comparison of simple and contrast-enhanced CT. The results thus suggest the usefulness of contrast-enhanced helical CT using SmartPrep in gynecology. (author)

  2. Helicity and potential vorticity in the surface boundary layer turbulence

    Science.gov (United States)

    Chkhetiani, Otto; Kurgansky, Michael; Koprov, Boris; Koprov, Victor

    2016-04-01

    An experimental measurement of all three components of the velocity and vorticity vectors, as well as the temperature and its gradient, and potential vorticity, has been developed using four acoustic anemometers. Anemometers were placed at vertices of a tetrahedron, the horizontal base of which was a rectangular triangle with equal legs, and the upper point was exactly above the top of the right angle. The distance from the surface to the tetrahedron its base was 5.5 m, and the lengths of legs and a vertical edge were 5 m. The measurements were carried out of total duration near 100 hours both in stable and unstable stratification conditions (at the Tsimlyansk Scientific Station in a uniform area of virgin steppe 700 x 650 m, August 2012). A covariance-correlation matrix for turbulent variations in all measured values has been calculated. In the daytime horizontal and vertical components of the helicity are of the order of -0.03 and +0.01 m s-2, respectively. The nighttime signs remain unchanged, but the absolute values are several times smaller. It is confirmed also by statistics of a relative helicity. The cospectra and spectral correlation coefficients have been calculated for all helicity components. The time variations in the components of "instantaneous" relative helicity and potential vorticity are considered. Connections of helicity with Monin-Obukhov length and the wind vertical profile structure are discussed. This work was supported by the Russian Science Foundation (Project No 14-27-00134).

  3. Structural analysis of compression helical spring used in suspension system

    Science.gov (United States)

    Jain, Akshat; Misra, Sheelam; Jindal, Arun; Lakhian, Prateek

    2017-07-01

    The main aim of this work has to develop a helical spring for shock absorber used in suspension system which is designed to reduce shock impulse and liberate kinetic energy. In a vehicle, it increases comfort by decreasing amplitude of disturbances and it improves ride quality by absorbing and dissipating energy. When a vehicle is in motion on a road and strikes a bump, spring comes into action quickly. After compression, spring will attempt to come to its equilibrium state which is on level road. Helical springs can be made lighter with more strength by reducing number of coils and increasing the area. In this research work, a helical spring is modeled and analyzed to substitute the existing steel spring which is used in suspension. By using different materials, stress and deflection of helical spring can be varied. Comparability between existing spring and newly replaced spring is used to verify the results. For finding detailed stress distribution, finite element analysis is used to find stresses and deflection in both the helical springs. Finite element analysis is a method which is used to find proximate solutions of a physical problem defined in a finite domain. In this research work, modeling of spring is accomplished using Solid Works and analysis on Ansys.

  4. Kinetic theory of rf current drive and helicity injection

    International Nuclear Information System (INIS)

    Mett, R.R.

    1992-01-01

    Current drive and helicity injection by plasma waves are examined with the use of kinetic theory. The Vlasov equation yields a general current drive formula that contains resonant and nonresonant (ponderomotivelike) contributions. Standard quasilinear current drive is described by the former, while helicity current drive may be contained in the latter. Since direct analytical comparison of the sizes of the two terms is, in general, difficult, a new approach is taken. Solution of the drift-kinetic equation shows that the standard Landau damping/transit time magnetic pumping quasilinear diffusion coefficient is the only contribution to steady-state current drive to leading order in ε=ρ L /l, where ρ L is the Larmor radius and l is the inhomogeneity scale length. All nonresonant contributions, including the helicity, appear at higher order, after averages are taken over a flux surface, over azimuth, and over time. Consequently, at wave frequencies well below the electron cyclotron frequency, a wave helicity flux perpendicular to the magnetic field does not influence the parallel motion of electrons to leading order and therefore will not drive a significant current. Any current associated with a wave helicity flux is then either ion current (and thus inefficient) or electron current stemming from effects not included in the drift-kinetic treatment, such as cyclotron, collisional, or nonlinear (i.e., not quasilinear)

  5. Reduced bispectrum seeded by helical primordial magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Hortúa, Héctor Javier [Universidad Nacional de Colombia-Bogotá, Facultad de Ciencias, Departamento de Física, Carrera 30 Calle 45-03, C.P. 111321 Bogotá (Colombia); Castañeda, Leonardo, E-mail: hjhortuao@unal.edu.co, E-mail: lcastanedac@unal.edu.co [Grupo de Gravitación y Cosmología, Observatorio Astronómico Nacional, Universidad Nacional de Colombia, cra 45 No 26-85, Edificio Uriel Gutierréz, Bogotá, D.C. (Colombia)

    2017-06-01

    In this paper, we investigate the effects of helical primordial magnetic fields (PMFs) on the cosmic microwave background (CMB) reduced bispectrum. We derive the full three-point statistics of helical magnetic fields and numerically calculate the even contribution in the collinear configuration. We then numerically compute the CMB reduced bispectrum induced by passive and compensated PMF modes on large angular scales. There is a negative signal on the bispectrum due to the helical terms of the fields and we also observe that the biggest contribution to the bispectrum comes from the non-zero IR cut-off for causal fields, unlike the two-point correlation case. For negative spectral indices, the reduced bispectrum is enhanced by the passive modes. This gives a lower value of the upper limit for the mean amplitude of the magnetic field on a given characteristic scale. However, high values of IR cut-off in the bispectrum, and the helical terms of the magnetic field relaxes this bound. This demonstrates the importance of the IR cut-off and helicity in the study of the nature of PMFs from CMB observations.

  6. l=1 helical axis heliotron device in Kyoto university

    International Nuclear Information System (INIS)

    Nagasaki, K.; Sano, F.; Mizuuchi, T.; Hanatani, K.; Okada, H.; Obiki, T.

    1999-01-01

    Helical systems are an attractive candidate for magnetic fusion reactor. Recently, there has been great progress in theoretical research of three dimensional magnetic field structures, resulting in several kinds of confinement optimization being proposed for toroidal magnetic confinement system. For example, some sophisticated ideas have appeared on stage such as quasi-helical symmetry and quasi-isodynamic system. To find experimentally which way is the best Optimisation, a new helical axis heliotron device, so called 'Heliotron J', is under construction in the Institute of Advanced Energy, Kyoto University, Japan. In this conference, the basic concept and the present status will be presented. In the conventional plane axis helical system, it was difficult to have both good particle confinement and good MHD stability simultaneously. The goal of Heliotron J project is to clarify their compatibility in the spatial axis toroidal device. The best way for Optimising the helical magnetic field configuration will be explored by investigating the plasma response to the change in the field components. The main subjects for plasma experiment are: demonstration of the existence of good magnetic flux surfaces, reduction of neoclassical transport in collisionless regime, MHD Stabilisation in high β plasma, controllability of bootstrap current, good confinement of high energy particles

  7. Controllable helical deformations on printed anisotropic composite soft actuators

    Science.gov (United States)

    Wang, Dong; Li, Ling; Serjouei, Ahmad; Dong, Longteng; Weeger, Oliver; Gu, Guoying; Ge, Qi

    2018-04-01

    Helical shapes are ubiquitous in both nature and engineering. However, the development of soft actuators and robots that mimic helical motions has been hindered primarily due to the lack of efficient modeling approaches that take into account the material anisotropy and the directional change of the external loading point. In this work, we present a theoretical framework for modeling controllable helical deformations of cable-driven, anisotropic, soft composite actuators. The framework is based on the minimum potential energy method, and its model predictions are validated by experiments, where the microarchitectures of the soft composite actuators can be precisely defined by 3D printing. We use the developed framework to investigate the effects of material and geometric parameters on helical deformations. The results show that material stiffness, volume fraction, layer thickness, and fiber orientation can be used to control the helical deformation of a soft actuator. In particular, we found that a critical fiber orientation angle exists at which the twist of the actuator changes the direction. Thus, this work can be of great importance for the design and fabrication of soft actuators with tailored deformation behavior.

  8. Double Helical Gear Performance Results in High Speed Gear Trains

    Science.gov (United States)

    Handschuh, Robert F.; Ehinger, Ryan; Sinusas, Eric; Kilmain, Charles

    2010-01-01

    The operation of high speed gearing systems in the transmissions of tiltrotor aircraft has an effect on overall propulsion system efficiency. Recent work has focused on many aspects of high-speed helical gear trains as would be used in tiltrotor aircraft such as operational characteristics, comparison of analytical predictions to experimental data and the affect of superfinishing on transmission performance. Baseline tests of an aerospace quality system have been conducted in the NASA Glenn High-Speed Helical Gear Train Test Facility and have been described in earlier studies. These earlier tests had utilized single helical gears. The results that will be described in this study are those attained using double helical gears. This type of gear mesh can be configured in this facility to either pump the air-oil environment from the center gap between the meshing gears to the outside of tooth ends or in the reverse direction. Tests were conducted with both inward and outward air-oil pumping directions. Results are compared to the earlier baseline results of single helical gears.

  9. Heat transfer characteristics of a helical heat exchanger

    International Nuclear Information System (INIS)

    San, Jung-Yang; Hsu, Chih-Hsiang; Chen, Shih-Hao

    2012-01-01

    Heat transfer performance of a helical heat exchanger was investigated. The heat exchanger is composed of a helical tube with rectangular cross section and two cover plates. The ε–Ntu relation of the heat exchanger was obtained using a numerical method. In the analysis, the flow in the tube (helical flow) was considered to be mixed and the flow outside the tube (radial flow) was unmixed. In the experiment, the Darcy friction factor (f) and convective heat transfer coefficient (h) of the radial flow were measured. The radial flow was air and the helical flow was water. Four different channel spacing (0.5, 0.8, 1.2 and 1.6 mm) were individually considered. The Reynolds numbers were in the range 307–2547. Two correlations, one for the Darcy friction factor and the other for the Nusselt number, were proposed. - Highlights: ► We analyze the heat transfer characteristics of a helical heat exchanger and examine the effectiveness–Ntu relation. ► Increasing number of turns of the heat exchanger would slightly increase the effectiveness. ► There is an optimum Ntu value corresponding to a maximum effectiveness. ► We measure the Darcy friction factor and Nusselt number of the radial flow and examine the correlations.

  10. Max-out-in pivot rule with Dantzig's safeguarding rule for the simplex method

    International Nuclear Information System (INIS)

    Tipawanna, Monsicha; Sinapiromsaran, Krung

    2014-01-01

    The simplex method is used to solve linear programming problem by improving the current basic feasible solution. It uses a pivot rule to guide the search in the feasible region. The pivot rule is used to select an entering index in simplex method. Nowadays, many pivot rule have been presented, but no pivot rule shows superior performance than other. Therefore, this is still an active research in linear programming. In this research, we present the max-out-in pivot rule with Dantzig's safeguarding for simplex method. This rule is based on maximum improvement of objective value of the current basic feasible point similar to the Dantzig's rule. We can illustrate by Klee and Minty problems that our rule outperforms that of Dantzig's rule by the number of iterations for solving linear programming problems

  11. Stable single helical C- and I-chains inside single-walled carbon nanotubes

    International Nuclear Information System (INIS)

    Yao Z; Li Y; Jing X D; Meng F S; Zhao X; Li J H; Qiu Z Y; Yuan Q; Wang W X; Bi L; Liu H; Zhang Y P; Liu C J; Zheng S P; Liu B B

    2016-01-01

    The helicity of stable single helical carbon chains and iodine chains inside single-walled carbon nanotubes (SWCNTs) is studied by calculating the systematic van der Waals interaction energy. The results show that the optimal helical radius increases linearly with increasing tube radius, which produces a constant separation between the chain structure and the tube wall. The helical angle exhibits a ladder-like decrease with increasing tube radius, indicating that a large tube can produce a small helicity in the helical structures. (paper)

  12. New reconstruction algorithm in helical-volume CT

    International Nuclear Information System (INIS)

    Toki, Y.; Rifu, T.; Aradate, H.; Hirao, Y.; Ohyama, N.

    1990-01-01

    This paper reports on helical scanning that is an application of continuous scanning CT to acquire volume data in a short time for three-dimensional study. In a helical scan, the patient couch sustains movement during continuous-rotation scanning and then the acquired data is processed to synthesize a projection data set of vertical section by interpolation. But the synthesized section is not thin enough; also, the image may have artifacts caused by couch movement. A new reconstruction algorithm that helps resolve such problems has been developed and compared with the ordinary algorithm. The authors constructed a helical scan system based on TCT-900S, which can perform 1-second rotation continuously for 30 seconds. The authors measured section thickness using both algorithms on an AAPM phantom, and we also compared degree of artifacts on clinical data

  13. Geometric scalings for the electrostatically driven helical plasma state

    Science.gov (United States)

    Akçay, Cihan; Finn, John M.; Nebel, Richard A.; Barnes, Daniel C.

    2017-12-01

    A new plasma state has been investigated [Akcay et al., Phys. Plasmas 24, 052503 (2017)], with a uniform applied axial magnetic field in a periodic cylinder of length L = 2 π R , driven by helical electrodes. The drive is single helicity, depending on m θ + k z = m θ - n ζ , where ζ = z / R and k = - n / R . For strong ( m , n ) = ( 1 , 1 ) drive, the state was found to have a strong axial mean current density, with a mean-field safety factor q 0 ( r ) just above the pitch of the electrodes m / n = 1 in the interior. This state has possible applications to DC electrical transformers and tailoring of the current profile in tokamaks. We study two geometric issues of interest for these applications: (i) scaling of properties with the plasma length or aspect ratio and (ii) behavior for different helicities, specifically ( m , n ) = ( 1 , n ) for n > 1 and ( m , n ) = ( 2 , 1 ) .

  14. Effect of loss cone on confinement in toroidal helical device

    International Nuclear Information System (INIS)

    Itoh, K.; Itoh, S.-I.; Fukuyama, A.; Hanatani, K.

    1988-12-01

    Analytical estimation is given on the loss cone in the toroidal helical devices in the presence of the radial electric field and the modulation of the helical ripple. The minimum energy of particles entering the loss cone is calculated. The modulation is not always effective in reducing the loss in the presence of the radial electric field. The plasma loss due to the loss cone is estimated in the collisionless limit. The radial electric field is estimated in the presence of the loss cone. It is found that the transition to the solution with positive radial electric field, which is necessary to achieve the high-ion-temperature mode, becomes difficult. This difficulty is large for the systems with the small helical ripple. (author)

  15. Geometric analysis of alloreactive HLA α-helices.

    Science.gov (United States)

    Ribarics, Reiner; Karch, Rudolf; Ilieva, Nevena; Schreiner, Wolfgang

    2014-01-01

    Molecular dynamics (MD) is a valuable tool for the investigation of functional elements in biomolecules, providing information on dynamic properties and processes. Previous work by our group has characterized static geometric properties of the two MHC α-helices comprising the peptide binding region recognized by T cells. We build upon this work and used several spline models to approximate the overall shape of MHC α-helices. We applied this technique to a series of MD simulations of alloreactive MHC molecules that allowed us to capture the dynamics of MHC α-helices' steric configurations. Here, we discuss the variability of spline models underlying the geometric analysis with varying polynomial degrees of the splines.

  16. Imploding to equilibrium of helically symmetric theta pinches

    International Nuclear Information System (INIS)

    Sharky, N.N.

    1978-01-01

    The time-dependent, single-fluid, dissipative magnetohydrodynamic equations are solved in helical coordinates (r,phi), where phi = THETA-kz, k = 2π/L and L is the periodicity length in the z-direction. The two-dimensional numerical calculations simulate theta pinches which have an l = 1 helical field added to them. Given the applied magnetic fields and the initial state of the plasma, we study the time evolution of the system. The plasma is found to experience two kinds of oscillations, occurring on different time scales. These are the radial compression oscillations, and the slower helical oscillations of the plasma column. The plasma motion is followed until these oscillations disappear and an equilibrium is nearly reached. Hence given the amplitude and the rise time of the applied magnetic fields, the calculations allow one to relate the initial state of a cold, homogeneous plasma to its final equilibrium state where it is heated and compressed

  17. Theory of dynamics in long pulse helical plasmas

    International Nuclear Information System (INIS)

    Itoh, K.; Sanuki, H.; Toda, S.; Yokoyama, M.; Itoh, S.-I.; Yagi, M.; Fukuyama, A.

    2001-01-01

    Self-organized dynamics of toroidal helical plasma, which is induced by the nonlinear transport property, is discussed. Neoclassical ripple diffusion is a dominant mechanism that drives the radial electric field. The bifurcation nature of the electric field generation gives rise to the electric field domain interface, across which the electric field changes strongly. This domain interface is an origin of internal transport barrier in helical systems. This nonlinearity gives rise to the self-organized oscillations; the electric field pulsation is one of the examples. Based on the model of density limit, in which the competition between the transport loss and radiation loss is analyzed, dynamics near the density limit of helical systems is also discussed. (author)

  18. Helicity amplitudes and electromagnetic decays of hyperon resonances

    International Nuclear Information System (INIS)

    Cauteren, T. van; Ryckebusch, J.; Metsch, B.; Petry, H.R.

    2005-01-01

    We present results for the helicity amplitudes of the lowest-lying hyperon resonances Y * , computed within the framework of the Bonn Constituent-Quark model, which is based on the Bethe-Salpeter approach. The seven parameters entering the model were fitted to the best-known baryon masses. Accordingly, the results for the helicity amplitudes are genuine predictions. Some hyperon resonances are seen to couple more strongly to a virtual photon with finite Q 2 than to a real photon. Other Y * 's, such as the S 01 (1670) Λ-resonance or the S 11 (1620) Σ-resonance, couple very strongly to real photons. We present a qualitative argument for predicting the behaviour of the helicity asymmetries of baryon resonances at high Q 2 . (orig.)

  19. A small-animal imaging system capable of multipinhole circular/helical SPECT and parallel-hole SPECT

    International Nuclear Information System (INIS)

    Qian Jianguo; Bradley, Eric L.; Majewski, Stan; Popov, Vladimir; Saha, Margaret S.; Smith, Mark F.; Weisenberger, Andrew G.; Welsh, Robert E.

    2008-01-01

    We have designed and built a small-animal single-photon emission computed tomography (SPECT) imaging system equipped with parallel-hole and multipinhole collimators and capable of circular or helical SPECT. Copper-beryllium parallel-hole collimators suitable for imaging the ∼35 keV photons from the decay of 125 I have been built and installed to achieve useful spatial resolution over a range of object-detector distances and to reduce imaging time on our dual-detector array. To address the resolution limitations in the parallel-hole SPECT and the sensitivity and limited field of view of single-pinhole SPECT, we have incorporated multipinhole circular and helical SPECT in addition to expanding the parallel-hole SPECT capabilities. The pinhole SPECT system is based on a 110 mm diameter circular detector equipped with a pixellated NaI(Tl) scintillator array (1x1x5 mm 3 /pixel). The helical trajectory is accomplished by two stepping motors controlling the rotation of the detector-support gantry and displacement of the animal bed along the axis of rotation of the gantry. Results obtained in SPECT studies of various phantoms show an enlarged field of view, very good resolution and improved sensitivity using multipinhole circular or helical SPECT. Collimators with one, three and five, 1-mm-diameter pinholes have been implemented and compared in these tests. Our objective is to develop a system on which one may readily select a suitable mode of either parallel-hole SPECT or pinhole circular or helical SPECT for a variety of small animal imaging applications

  20. Handling data redundancy in helical cone beam reconstruction with a cone-angle-based window function and its asymptotic approximation

    International Nuclear Information System (INIS)

    Tang Xiangyang; Hsieh Jiang

    2007-01-01

    A cone-angle-based window function is defined in this manuscript for image reconstruction using helical cone beam filtered backprojection (CB-FBP) algorithms. Rather than defining the window boundaries in a two-dimensional detector acquiring projection data for computed tomographic imaging, the cone-angle-based window function deals with data redundancy by selecting rays with the smallest cone angle relative to the reconstruction plane. To be computationally efficient, an asymptotic approximation of the cone-angle-based window function is also given and analyzed in this paper. The benefit of using such an asymptotic approximation also includes the avoidance of functional discontinuities that cause artifacts in reconstructed tomographic images. The cone-angle-based window function and its asymptotic approximation provide a way, equivalent to the Tam-Danielsson-window, for helical CB-FBP reconstruction algorithms to deal with data redundancy, regardless of where the helical pitch is constant or dynamically variable during a scan. By taking the cone-parallel geometry as an example, a computer simulation study is conducted to evaluate the proposed window function and its asymptotic approximation for helical CB-FBP reconstruction algorithm to handle data redundancy. The computer simulated Forbild head and thorax phantoms are utilized in the performance evaluation, showing that the proposed cone-angle-based window function and its asymptotic approximation can deal with data redundancy very well in cone beam image reconstruction from projection data acquired along helical source trajectories. Moreover, a numerical study carried out in this paper reveals that the proposed cone-angle-based window function is actually equivalent to the Tam-Danielsson-window, and rigorous mathematical proofs are being investigated

  1. Technical rules in law

    Energy Technology Data Exchange (ETDEWEB)

    Debelius, J

    1978-08-01

    An important source of knowledge for technical experts is the state of the art reflected by catalogues of technical rules. Technical rules may also achieve importance in law due to a legal transformation standard. Here, rigid and flexible reference are controversial with regard to their admissibility from the point of view of constitutional law. In case of a divergence from the generally accepted technical rules, it is assumed - refutably - that the necessary care had not been taken. Technical rules are one out of several sources of information; they have no normative effect. This may result in a duty of anyone applying them to review the state of technology himself.

  2. Technical rules in law

    International Nuclear Information System (INIS)

    Debelius, J.

    1978-01-01

    An important source of knowledge for technical experts is the state of the art reflected by catalogues of technical rules. Technical rules may also achieve importance in law due to a legal transformation standard. Here, rigid and flexible reference are controversial with regard to their admissibility from the point of view of constitutional law. In case of a divergence from the generally accepted technical rules, it is assumed - refutably - that the necessary care had not been taken. Technical rules are one out of several sources of information; they have no normative effect. This may result in a duty of anyone applying them to review the state of technology himself. (orig.) [de

  3. Conformal avoidance helical tomotherapy for dogs with nasopharyngeal tumors

    International Nuclear Information System (INIS)

    Welsh, J.S.; Turek, M.; Mackie, T.R.; Miller, P.; Mehta, M.P.; Forrest, L.J.

    2003-01-01

    Helical tomotherapy provides a unique means of delivering intensity-modulated radiation therapy (IMRT) using a novel treatment unit, which merges features of a linear accelerator with a helical CT scanner. Thanks to the CT imaging capacity, targeted regions can be visualized prior to, during, or immediately after each treatment. Such image-guidance through megavoltage CT will allow the realization and refinement of the concept of adaptive radiotherapy - the reconstruction of the actually delivered daily dose (as opposed to planned dose) accompanied by prescription adjustments when appropriate. In addition to this unique feature, helical tomotherapy promises further improvements in the specific avoidance of critical normal structures, i.e. conformal avoidance, the counterpart of conformal therapy. The first definitive treatment protocol using helical tomotherapy is presently underway for dogs with nasopharyngeal tumors. In general, such tumors can be treated with conventional external beam radiation therapy but at the cost of severe ocular toxicity due to the anatomy of the canine head. These are readily measurable toxicities and are almost universal in incidence; therefore, the canine nasopharyngeal tumor presents an ideal model to assess the ability to conformally avoid critical structures. It is hoped that conformal avoidance helical tomotherapy will improve tumor control via dose-escalation while reducing ocular toxicity in these veterinary patients. A total of 10 fractions are scheduled for these patients; the first 3 dogs have all received at least 7 fractions delivered via helical tomotherapy. Although preliminary, the first 3 dogs treated have not shown any evidence of ocular toxicity in this ongoing study

  4. Divertors for Helical Devices: Concepts, Plans, Results, and Problems

    International Nuclear Information System (INIS)

    Koenig, R.; Grigull, P.; McCormick, K.

    2004-01-01

    With Large Helical Device (LHD) and Wendelstein 7-X (W7-X), the development of helical devices is now taking a large step forward on the path to a steady-state fusion reactor. Important issues that need to be settled in these machines are particle flux and heat control and the impact of divertors on plasma performance in future continuously burning fusion plasmas. The divertor concepts that will initially be explored in these large machines were prepared in smaller-scale devices like Heliotron E, Compact Helical System (CHS), and Wendelstein 7-AS (W7-AS). While advanced divertor scenarios relevant for W7-X were already studied in W7-AS, other smaller-scale experiments like Heliotron-J, CHS, and National Compact Stellarator Experiment will be used for the further development of divertor concepts. The two divertor configurations that are being investigated are the helical and the island divertor, as well as the local island divertor, which was successfully demonstrated on CHS and just went into operation on LHD. At present, on its route to a fully closed helical divertor, LHD operates in an open helical divertor configuration. W7-X will be equipped right from the start with an actively cooled discrete island divertor that will allow quasi-continuous operation. The divertor design is very similar to the one explored on W7-AS. For sufficiently large island sizes and not too long field line connection lengths, this divertor gives access to a partially detached quasi-steady-state operating scenario in a newly found high-density H-mode operating regime, which benefits from high energy and low impurity confinement times, with edge radiation levels of up to 90% and sufficient neutral compression in the subdivertor region (>10) for active pumping. The basic physics of the different divertor concepts and associated implementation problems, like asymmetries due to drifts, accessibility of essential operating scenarios, toroidal asymmetries due to symmetry breaking error fields

  5. Variation in the helical structure of native collagen.

    Directory of Open Access Journals (Sweden)

    Joseph P R O Orgel

    Full Text Available The structure of collagen has been a matter of curiosity, investigation, and debate for the better part of a century. There has been a particularly productive period recently, during which much progress has been made in better describing all aspects of collagen structure. However, there remain some questions regarding its helical symmetry and its persistence within the triple-helix. Previous considerations of this symmetry have sometimes confused the picture by not fully recognizing that collagen structure is a highly complex and large hierarchical entity, and this affects and is effected by the super-coiled molecules that make it. Nevertheless, the symmetry question is not trite, but of some significance as it relates to extracellular matrix organization and cellular integration. The correlation between helical structure in the context of the molecular packing arrangement determines which parts of the amino acid sequence of the collagen fibril are buried or accessible to the extracellular matrix or the cell. In this study, we concentrate primarily on the triple-helical structure of fibrillar collagens I and II, the two most predominant types. By comparing X-ray diffraction data collected from type I and type II containing tissues, we point to evidence for a range of triple-helical symmetries being extant in the molecules native environment. The possible significance of helical instability, local helix dissociation and molecular packing of the triple-helices is discussed in the context of collagen's supramolecular organization, all of which must affect the symmetry of the collagen triple-helix.

  6. Point contacts and localization in generic helical liquids

    Science.gov (United States)

    Orth, Christoph P.; Strübi, Grégory; Schmidt, Thomas L.

    2013-10-01

    We consider two helical liquids on opposite edges of a two-dimensional topological insulator, which are connected by one or several local tunnel junctions. In the presence of spatially inhomogeneous Rashba spin-orbit coupling, the spin of the helical edge states is momentum dependent, and this spin texture can be different on opposite edges. We demonstrate that this has a strong impact on the electron transport between the edges. In particular, in the case of many random tunnel contacts, the localization length depends strongly on the spin textures of the edge states.

  7. Effects of different rod spacers (helical types) on coolant crossmixing

    International Nuclear Information System (INIS)

    Zhukov, A.V.; Sviridenko, E.Ya.; Matyukhin, N.M.; Rymkevich, K.S.; Ushakov, P.A.

    1981-11-01

    The results of investigations (electromagnetic measuring method) on coolant cross mixing in rod clusters with spiral wire spacers with different winding directions, with alternating unfinned and finned rods (case 'fin to rod'), as well as in rod clusters with much space between the rods, (case 'fin to fin') are reported. The local fluid dynamics parameters (distribution of the transversal and longitudinal velocity component) that define the physical processes of the coolant exchange in the rod clusters with helical spacers are explained. The investigation results for different helical spacer types are compared with each other. (orig.) [de

  8. Demonstration of a helical armature for a superconducting generator

    International Nuclear Information System (INIS)

    Conley, P.L.; Kirtley, J.L. Jr.; Hagman, W.H.; Ula, A.H.M.S.

    1979-01-01

    This is a report on the design, construction and testing of an experimental helical armature for a superconducting geneator. Rated at 60 kVA, this armature was built to be operated in conjunction with the rotor of the first experimental superconducting machine built at MIT. It incorporates, in addition to the helical winding form, a high density edge-brazed end turn geometry, molded bar groups, and silicone fluid coolant and insulation impregnant. Tests showed that the thermal performance of the armature was within reasonable limits, magnetic analyses leading to the computation of reactance and voltage geneation were approximately correct. No abnormal cheating was observed. 9 refs

  9. Helically symmetric equilibria with pressure anisotropy and incompressible plasma flow

    Science.gov (United States)

    Evangelias, A.; Kuiroukidis, A.; Throumoulopoulos, G. N.

    2018-02-01

    We derive a generalized Grad-Shafranov equation governing helically symmetric equilibria with pressure anisotropy and incompressible flow of arbitrary direction. Through the most general linearizing ansatz for the various free surface functions involved therein, we construct equilibrium solutions and study their properties. It turns out that pressure anisotropy can act either paramegnetically or diamagnetically, the parallel flow has a paramagnetic effect, while the non-parallel component of the flow associated with the electric field has a diamagnetic one. Also, pressure anisotropy and flow affect noticeably the helical current density.

  10. Synthesis, model and stability of helically coiled carbon nanotubes

    DEFF Research Database (Denmark)

    Fejes, Dora; Raffai, Manuella; Hernadi, Klara

    2013-01-01

    . Our experiments focused on the production and development of catalysts for the synthesis of helically coiled CNTs (carbon nanotubes). The catalysts were tested in the decomposition of acetylene by CCVD (Catalytic Chemical Vapor Deposition) method. The carbon deposit was imaged by TEM (Transmission......Structural model of helically coiled carbon nanotubes is proposed. It is constructed by means of topological coordinate method. Relaxation and cohesive energy calculation are performed by molecular mechanics, using second-generation bond order potential for hydrocarbons introduced by D. W. Brenner...

  11. Strategy as simple rules.

    Science.gov (United States)

    Eisenhardt, K M; Sull, D N

    2001-01-01

    The success of Yahoo!, eBay, Enron, and other companies that have become adept at morphing to meet the demands of changing markets can't be explained using traditional thinking about competitive strategy. These companies have succeeded by pursuing constantly evolving strategies in market spaces that were considered unattractive according to traditional measures. In this article--the third in an HBR series by Kathleen Eisenhardt and Donald Sull on strategy in the new economy--the authors ask, what are the sources of competitive advantage in high-velocity markets? The secret, they say, is strategy as simple rules. The companies know that the greatest opportunities for competitive advantage lie in market confusion, but they recognize the need for a few crucial strategic processes and a few simple rules. In traditional strategy, advantage comes from exploiting resources or stable market positions. In strategy as simple rules, advantage comes from successfully seizing fleeting opportunities. Key strategic processes, such as product innovation, partnering, or spinout creation, place the company where the flow of opportunities is greatest. Simple rules then provide the guidelines within which managers can pursue such opportunities. Simple rules, which grow out of experience, fall into five broad categories: how- to rules, boundary conditions, priority rules, timing rules, and exit rules. Companies with simple-rules strategies must follow the rules religiously and avoid the temptation to change them too frequently. A consistent strategy helps managers sort through opportunities and gain short-term advantage by exploiting the attractive ones. In stable markets, managers rely on complicated strategies built on detailed predictions of the future. But when business is complicated, strategy should be simple.

  12. Rules, culture, and fitness.

    Science.gov (United States)

    Baum, W M

    1995-01-01

    Behavior analysis risks intellectual isolation unless it integrates its explanations with evolutionary theory. Rule-governed behavior is an example of a topic that requires an evolutionary perspective for a full understanding. A rule may be defined as a verbal discriminative stimulus produced by the behavior of a speaker under the stimulus control of a long-term contingency between the behavior and fitness. As a discriminative stimulus, the rule strengthens listener behavior that is reinforced in the short run by socially mediated contingencies, but which also enters into the long-term contingency that enhances the listener's fitness. The long-term contingency constitutes the global context for the speaker's giving the rule. When a rule is said to be "internalized," the listener's behavior has switched from short- to long-term control. The fitness-enhancing consequences of long-term contingencies are health, resources, relationships, or reproduction. This view ties rules both to evolutionary theory and to culture. Stating a rule is a cultural practice. The practice strengthens, with short-term reinforcement, behavior that usually enhances fitness in the long run. The practice evolves because of its effect on fitness. The standard definition of a rule as a verbal statement that points to a contingency fails to distinguish between a rule and a bargain ("If you'll do X, then I'll do Y"), which signifies only a single short-term contingency that provides mutual reinforcement for speaker and listener. In contrast, the giving and following of a rule ("Dress warmly; it's cold outside") can be understood only by reference also to a contingency providing long-term enhancement of the listener's fitness or the fitness of the listener's genes. Such a perspective may change the way both behavior analysts and evolutionary biologists think about rule-governed behavior.

  13. Helical CT of traumatic injuries of the thoracic aorta

    International Nuclear Information System (INIS)

    Mengozzi, E.; Burzi, M.; Miceli, M.; Lipparini, M.; Sartoni Galloni, S.

    2000-01-01

    Acute thoracic aortic injuries account for up to 10-20% of fatalities in high-speed deceleration road accidents and have an estimated immediate fatality rate of 80-90%. Untreated survivors to acute trauma (10-20%) have a dismal prognosis: 30% of them die within 6 hours, 40-50% die within 24 hours, and 90% within 4 months. It was investigated the diagnostic accuracy of Helical Computed Tomography (Helical CT) in acute traumatic injuries of the thoracic aorta, and the role of this technique in the diagnostic management of trauma patients with a strong suspicion of aortic rupture. It was compared retrospectively the chest Helical CT findings of 256 trauma patients examined June 1995 through August 1999. Chest Helical CT examinations were performed according to trauma score, to associated traumatic lesions and to plain chest radiographic findings. All the examinations were performed with no intravenous contrast agent administration and the pitch 2 technique. After a previous baseline study, contrast-enhanced scans were acquired with pitch 1 in 87 patients. Helical CT showed aortic lesions in 9 of 256 patients examined. In all the 9 cases it was found a mediastinal hematoma and all of them had positive plain chest radiographic findings of mediastinal enlargement. Moreover, in 6 cases aortic knob blurring was also evident on plain chest film and in 5 cases depressed left mainstem bronchus and trachea deviation rightwards were observed. All aortic lesions were identified on axial scans and located at the isthmus of level. Aortic rupture was always depicted as pseudo diverticulum of the proximal descending tract and intimal flap. It was also found that periaortic hematoma in 6 cases and intramural hematoma in 1 case. There were non false positive results in the series: 7 patients with Helical CT diagnosis of aortic rupture were submitted to conventional aortography that confirmed both type and extension of the lesions as detected by Helical CT, and all findings were

  14. Roles of effective helical ripple rates in nonlinear stability of externally induced magnetic islands

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Seiya, E-mail: n-seiya@kobe-kosen.ac.jp [Kobe City College of Technology, Kobe, Hyogo 651-2194 (Japan)

    2015-02-15

    Magnetic islands are externally produced by resonant magnetic perturbations (RMPs) in toroidal plasmas. Spontaneous annihilation of RMP-induced magnetic islands called self-healing has been observed in helical systems. A possible mechanism of the self-healing is shielding of RMP penetration by helical ripple-induced neoclassical flows, which give rise to neoclassical viscous torques. In this study, effective helical ripple rates in multi-helicity helical systems are revisited, and a multi-helicity effect on the self-healing is investigated, based on a theoretical model of rotating magnetic islands. It is confirmed that effective helical ripple rates are sensitive to magnetic axis positions. It is newly found that self-healing thresholds also strongly depend on magnetic axis positions, which is due to dependence of neoclassical viscous torques on effective helical ripple rates.

  15. Rules and routines in organizations and the management of safety rules

    Energy Technology Data Exchange (ETDEWEB)

    Weichbrodt, J. Ch.

    2013-07-01

    This thesis is concerned with the relationship between rules and routines in organizations and how the former can be used to steer the latter. Rules are understood as formal organizational artifacts, whereas organizational routines are collective patterns of action. While research on routines has been thriving, a clear understanding of how rules can be used to influence or control organizational routines (and vice-versa) is still lacking. This question is of particular relevance to safety rules in high-risk organizations, where the way in which organizational routines unfold can ultimately be a matter of life and death. In these organizations, an important and related issue is the balancing of standardization and flexibility – which, in the case of rules, takes the form of finding the right degree of formalization. In high-risk organizations, the question is how to adequately regulate actors’ routines in order to facilitate safe behavior, while at the same time leaving enough leeway for actors to make good decisions in abnormal situations. The railroads are regarded as high-risk industries and also rely heavily on formal rules. In this thesis, the Swiss Federal Railways (SBB) were therefore selected for a field study on rules and routines. The issues outlined so far are being tackled theoretically (paper 1), empirically (paper 2), and from a practitioner’s (i.e., rule maker’s) point of view (paper 3). In paper 1, the relationship between rules and routines is theoretically conceptualized, based on a literature review. Literature on organizational control and coordination, on rules in human factors and safety, and on organizational routines is combined. Three distinct roles (rule maker, rule supervisor, and rule follower) are outlined. Six propositions are developed regarding the necessary characteristics of both routines and rules, the respective influence of the three roles on the rule-routine relationship, and regarding organizational aspects such as

  16. Rules and routines in organizations and the management of safety rules

    International Nuclear Information System (INIS)

    Weichbrodt, J. Ch.

    2013-01-01

    This thesis is concerned with the relationship between rules and routines in organizations and how the former can be used to steer the latter. Rules are understood as formal organizational artifacts, whereas organizational routines are collective patterns of action. While research on routines has been thriving, a clear understanding of how rules can be used to influence or control organizational routines (and vice-versa) is still lacking. This question is of particular relevance to safety rules in high-risk organizations, where the way in which organizational routines unfold can ultimately be a matter of life and death. In these organizations, an important and related issue is the balancing of standardization and flexibility – which, in the case of rules, takes the form of finding the right degree of formalization. In high-risk organizations, the question is how to adequately regulate actors’ routines in order to facilitate safe behavior, while at the same time leaving enough leeway for actors to make good decisions in abnormal situations. The railroads are regarded as high-risk industries and also rely heavily on formal rules. In this thesis, the Swiss Federal Railways (SBB) were therefore selected for a field study on rules and routines. The issues outlined so far are being tackled theoretically (paper 1), empirically (paper 2), and from a practitioner’s (i.e., rule maker’s) point of view (paper 3). In paper 1, the relationship between rules and routines is theoretically conceptualized, based on a literature review. Literature on organizational control and coordination, on rules in human factors and safety, and on organizational routines is combined. Three distinct roles (rule maker, rule supervisor, and rule follower) are outlined. Six propositions are developed regarding the necessary characteristics of both routines and rules, the respective influence of the three roles on the rule-routine relationship, and regarding organizational aspects such as

  17. Binary effectivity rules

    DEFF Research Database (Denmark)

    Keiding, Hans; Peleg, Bezalel

    2006-01-01

    is binary if it is rationalized by an acyclic binary relation. The foregoing result motivates our definition of a binary effectivity rule as the effectivity rule of some binary SCR. A binary SCR is regular if it satisfies unanimity, monotonicity, and independence of infeasible alternatives. A binary...

  18. Delayed rule following.

    Science.gov (United States)

    Schmitt, D R

    2001-01-01

    Although the elements of a fully stated rule (discriminative stimulus [S(D)], some behavior, and a consequence) can occur nearly contemporaneously with the statement of the rule, there is often a delay between the rule statement and the S(D). The effects of this delay on rule following have not been studied in behavior analysis, but they have been investigated in rule-like settings in the areas of prospective memory (remembering to do something in the future) and goal pursuit. Discriminative events for some behavior can be event based (a specific setting stimulus) or time based. The latter are more demanding with respect to intention following and show age-related deficits. Studies suggest that the specificity with which the components of a rule (termed intention) are stated has a substantial effect on intention following, with more detailed specifications increasing following. Reminders of an intention, too, are most effective when they refer specifically to both the behavior and its occasion. Covert review and written notes are two effective strategies for remembering everyday intentions, but people who use notes appear not to be able to switch quickly to covert review. By focusing on aspects of the setting and rule structure, research on prospective memory and goal pursuit expands the agenda for a more complete explanation of rule effects.

  19. "Chaos Rules" Revisited

    Science.gov (United States)

    Murphy, David

    2011-01-01

    About 20 years ago, while lost in the midst of his PhD research, the author mused over proposed titles for his thesis. He was pretty pleased with himself when he came up with "Chaos Rules" (the implied double meaning was deliberate), or more completely, "Chaos Rules: An Exploration of the Work of Instructional Designers in Distance Education." He…

  20. Evaluation of mixing rules for VLE calculations

    International Nuclear Information System (INIS)

    Adachi, Y.; Chung, W.K.; Lu, B.C.Y.; Yu, J.M.

    1983-01-01

    This chapter calculates vapor-liquid equilibrium (VLE) values for a number of binary systems of cryogenic interest, including hydrogen- and helium-containing mixtures, by means of several selected cubic equations of state using different sets of mixing rules. The aim is to test the capabilities of these equations for representing VLE values for the selected mixtures, and to identify and recommend the most suitable equation of state together with its compatible mixing rules for the desired data representation. It is determined that the conventional mixing rules together with the modified van der Waals equation, or the four-parameter equation, are suitable for calculating VLE values for the selected systems at cryogenic conditions. The Peng-Robinson and four-parameter equations may yield slightly better results for helium-containing systems

  1. Electronuclear sum rules

    International Nuclear Information System (INIS)

    Arenhoevel, H.; Drechsel, D.; Weber, H.J.

    1978-01-01

    Generalized sum rules are derived by integrating the electromagnetic structure functions along lines of constant ratio of momentum and energy transfer. For non-relativistic systems these sum rules are related to the conventional photonuclear sum rules by a scaling transformation. The generalized sum rules are connected with the absorptive part of the forward scattering amplitude of virtual photons. The analytic structure of the scattering amplitudes and the possible existence of dispersion relations have been investigated in schematic relativistic and non-relativistic models. While for the non-relativistic case analyticity does not hold, the relativistic scattering amplitude is analytical for time-like (but not for space-like) photons and relations similar to the Gell-Mann-Goldberger-Thirring sum rule exist. (Auth.)

  2. Finite element analysis of helical flows in human aortic arch: A novel index

    OpenAIRE

    Lee, Cheng-Hung; Liu, Kuo-Sheng; Jhong, Guan-Heng; Liu, Shih-Jung; Hsu, Ming-Yi; Wang, Chao-Jan; Hung, Kuo-Chun

    2014-01-01

    This study investigates the helical secondary flows in the aortic arch using finite element analysis. The relationship between helical flow and the configuration of the aorta in patients of whose three-dimensional images constructed from computed tomography scans was examined. A finite element model of the pressurized root, arch, and supra-aortic vessels was developed to simulate the pattern of helical secondary flows. Calculations indicate that most of the helical secondary flow was formed i...

  3. RIGHTS, RULES, AND DEMOCRACY

    Directory of Open Access Journals (Sweden)

    Richard S. Kay, University of Connecticut-School of Law, Estados Unidos

    2012-11-01

    Full Text Available Abstract: Democracy require protection of certain fundamental rights, but can we expect courts to follow rules? There seems little escape from the proposition that substantive constitutional review by an unelected judiciary is a presumptive abridgement of democratic decision-making. Once we have accepted the proposition that there exist human rights that ought to be protected, this should hardly surprise us. No one thinks courts are perfect translators of the rules invoked before them on every occasion. But it is equally clear that rules sometimes do decide cases. In modern legal systems the relative roles of courts and legislators with respect to the rules of the system is a commonplace. Legislatures make rules. Courts apply them in particular disputes. When we are talking about human rights, however, that assumption must be clarified in at least one way. The defense of the practice of constitutional review in this article assumes courts can and do enforce rules. This article also makes clear what is the meaning of “following rules”. Preference for judicial over legislative interpretation of rights, therefore, seems to hang on the question of whether or not judges are capable of subordinating their own judgment to that incorporated in the rules by their makers. This article maintains that, in general, entrenched constitutional rules (and not just constitutional courts can and do constrain public conduct and protect human rights. The article concludes that the value judgments will depend on our estimate of the benefits we derive from the process of representative self-government. Against those benefits we will have to measure the importance we place on being able to live our lives with the security created by a regime of human rights protected by the rule of law. Keywords: Democracy. Human Rights. Rules. Judicial Review.

  4. Investigation of Accelerated Partial Breast Patient Alignment and Treatment With Helical Tomotherapy Unit

    International Nuclear Information System (INIS)

    Langen, Katja M.; Buchholz, Daniel J.; Burch, Doug R. C.; Burkavage, Rob C.; Limaye, Arti U.; Meeks, Sanford L.; Kupelian, Patrick A.; Ruchala, Kenneth J.; Haimerl, Jason; Henderson, Doug; Olivera, Gustavo H.

    2008-01-01

    Purpose: To determine the precision of megavoltage computed tomography (MVCT)-based alignment of the seroma cavity for patients undergoing partial breast irradiation; and to determine whether accelerated partial breast irradiation (APBI) plans can be generated for TomoTherapy deliveries that meet the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-39/Radiation Therapy Oncology Group (RTOG) 0413 protocol guidelines for target coverage and normal tissue dose limitations. Methods and Materials: We obtained 50 MVCT images from 10 patients. An interuser study was designed to assess the alignment precision. Using a standard helical and a fixed beam prototype ('topotherapy') optimizer, two APBI plans for each patient were developed. Results: The precision of the MVCT-based seroma cavity alignment was better than 2 mm if averaged over the patient population. Both treatment techniques could be used to generate acceptable APBI plans for patients that fulfilled the recommended NSABP B-39/RTOG-0413 selection criteria. For plans of comparable treatment time, the conformation of the prescription dose to the target was greater for helical deliveries, while the ipsilateral lung dose was significantly reduced for the topotherapy plans. Conclusions: The inherent volumetric imaging capabilities of a TomoTherapy Hi-Art unit allow for alignment of patients undergoing partial breast irradiation that is determined from the visibility of the seroma cavity on the MVCT image. The precision of the MVCT-based alignment was better than 2 mm (± standard deviation) when averaged over the patient population. Using the NSABP B-39/RTOG-0413 guidelines, acceptable APBI treatment plans can be generated using helical- or topotherapy-based delivery techniques

  5. Determination of optimal parameters for three-dimensional reconstruction images of central airways using helical CT

    International Nuclear Information System (INIS)

    Hirose, Takahumi; Akata, Soichi; Matsuno, Naoto; Nagao, Takeshi; Abe, Kimihiko

    2002-01-01

    Three-dimensional (3D) image reconstruction of central airways using helical CT requires several user-defined parameters that exceed the requirements of conventional CT. The purpose of this study was to evaluate the optimal parameters for 3D images of central airways using helical CT. In our experimental study using a piglet immediately after sacrifice, 3D images of the central airway were evaluated with changes of 3D imaging parameters, such as detector collimation (1, 2, 3 and 6 mm), table speed (1, 2, 3 and 5 mm/sec), tube electric current (50, 100, 150, 200 and 250 mA), reconstruction interval (0.3, 0.5, 1, 2 and 3 mm), algorithm (mediastinum and lung) and interpolation method (180 deg and 360 deg). To minimize detector collimation, table speed, and reconstruction interval could provide the best 3D images of the central airway. Stair-step artifacts could also be reduced with a slow table speed. However, decreasing the collimation and table speed decreases not only the effective section thickness but also the scan coverage that can be achieved with a helical CT. For routine diagnosis, we conclude that optimal parameters for 3D images of the central airway are to minimize the table speed necessary to cover the volume of interest and to set detector collimation to 1/2 of the table speed. The reconstruction intervals should also be selected at up to 1/2 of the detector collimation, but with trade-offs of increased image processing time, data storage requirements, and physician time for image review. Regarding to tube electric current, 200 mA or more was necessary. Pixel noise increased with the algorithm for the lung. The 180 deg interpolation is better than 360 deg interpolation due to thin effective section thickness. (author)

  6. Ignition access in a D-3He helical reactor

    International Nuclear Information System (INIS)

    Mitarai, Osamu

    2003-01-01

    Ignition access in a D- 3 He helical reactor is studied based on 0-dimensional particle and power balance equations for deuterium, tritium, helium-3, alpha ash, proton ash, electron density and temperature. The calculations are based on the following experimental facts observed in LHD. (author)

  7. Field-theoretic calculation of kinetic helicity flux

    Indian Academy of Sciences (India)

    Given all these practical aspects, kinetic helicity is an important quantity to study in fluid turbulence. Turbulence involves millions of interacting modes. It is very difficult to analyze these modes theoretically as well as numerically. In recent times, a new numeri- cal procedure called 'large eddy simulations' (LES) has become ...

  8. Signs of helicity in solar prominences and related features

    Science.gov (United States)

    Martin, S.

    This review illustrates several ways to identify the chirality (handedness) of solar prominences (filaments) from their structure and the structure of their surrounding magnetic fields in the chromosphere and corona. For prominences, these structural elements include the axial magnetic field direction, orientation of barbs, and direction of the prominence fine structure. The surrounding structures include the pattern of fibrils beneath the prominences and the pattern of coronal loops above the prominences. These ways of identifying chirality are then interpreted in terms of the formal definitions of helicity to yield a consistent set of one-to-one helicity relationships for all features. The helicity of some prominences can also be independently determined during their eruption by their fine structure, apparent crossings in the line-of-sight of different parts of the same prominence, and by large- scale twist of the prominence structure. Unlike observations of prominences (filaments) observed prior to eruption, in some cases evidence of both signs of helicity are found within the same erupting prominence. This indicates the continued application of forces on the prominences during the eruption process or the possible introduction of force(s) not present during earlier stages of their evolution.

  9. Is gadolinium a helical antiferromagnet or a collinear ferromagnet?

    Indian Academy of Sciences (India)

    that a helical spin structure similar to that prevalent in other heavy rare-earth .... magnetocrystalline anisotropy factor, HK is the uniaxial anisotropy field and MS is .... lends firm support to the observation that the asymptotic critical behaviour of ...

  10. Helical Phase Inflation and Monodromy in Supergravity Theory

    Directory of Open Access Journals (Sweden)

    Tianjun Li

    2015-01-01

    Full Text Available We study helical phase inflation which realizes “monodromy inflation” in supergravity theory. In the model, inflation is driven by the phase component of a complex field whose potential possesses helicoid structure. We construct phase monodromy based on explicitly breaking global U(1 symmetry in the superpotential. By integrating out heavy fields, the phase monodromy from single complex scalar field is realized and the model fulfills natural inflation. The phase-axion alignment is achieved from explicitly symmetry breaking and gives super-Planckian phase decay constant. The F-term scalar potential provides strong field stabilization for all the scalars except inflaton, which is protected by the approximate global U(1 symmetry. Besides, we show that helical phase inflation can be naturally realized in no-scale supergravity with SU(2,1/SU(2×U(1 symmetry since the supergravity setup needed for phase monodromy is automatically provided in the no-scale Kähler potential. We also demonstrate that helical phase inflation can be reduced to another well-known supergravity inflation model with shift symmetry. Helical phase inflation is free from the UV-sensitivity problem although there is super-Planckian field excursion, and it suggests that inflation can be effectively studied based on supersymmetric field theory while a UV-completed framework is not prerequisite.

  11. Study of electric field pulsation in helical plasmas

    International Nuclear Information System (INIS)

    Toda, S; Itoh, K

    2011-01-01

    A model for the experimental results of the periodic oscillation of the electric field, so-called the electric field pulsation, observed in the Compact Helical Device (Fujisawa et al 1998 Phys. Rev. Lett. 81 2256) and the Large Helical Device (Shimizu et al 2010 Plasma Fusion Res. 5 S1015) is presented. A self-generated oscillation of the radial electric field is shown as the simulation result in helical plasmas. The reduction of the anomalous transport diffusivity in the core region is observed due to the strong shear of the radial electric field when the positive electric field is shown in the core region in the periodic oscillation of E r . Two different time scales are found in the self-generated oscillation, which are the transport time scale and the fast time scale at the transition of the radial electric field. This oscillation because of the hysteresis characteristic is attributed to the electric field pulsation observed in helical plasmas. The parameter region of the condition for the self-generated oscillation is derived. It is shown that the multiple solutions of the radial electric field for the ambipolar condition are necessary but not sufficient for obtaining the self-generated oscillation.

  12. Initial Results from Coaxial Helicity Injection Experiments in NSTX

    International Nuclear Information System (INIS)

    Raman, R.; Jarboe, T.R.; Mueller, D.; Schaffer, M.J.; Maqueda, R.; Nelson, B.A.; Sabbagh, S.; Bell, M.; Ewig, R.; Fredrickson, E.; Gates, D.; Hosea, J.; Ji, H.; Kaita, R.; Kaye, S.M.; Kugel, H.; Maingi, R.; Menard, J.; Ono, M.; Orvis, D.; Paolette, F.; Paul, S.; Peng, M.; Skinner, C.H.; Wilgen, W.; Zweben, S.

    2001-01-01

    Coaxial Helicity Injection (CHI) has been investigated on the National Spherical Torus Experiment (NSTX). Initial experiments produced 130 kA of toroidal current without the use of the central solenoid. The corresponding injector current was 20 kA. Discharges with pulse lengths up to 130 ms have been produced

  13. Overview of quasi single helicity experiments in reversed field pinches

    International Nuclear Information System (INIS)

    Martin, P.; Marrelli, L.; Spizzo, G.

    2003-01-01

    We report the results of an experimental and theoretical project dedicated to the study of Quasi Single Helicity Reversed Field Pinch plasmas. The project has involved several RFP devices and numerical codes. It appears that QSH spectra are a feature common to all the experiments. (author)

  14. Deceleration of arginine kinase refolding by induced helical structures.

    Science.gov (United States)

    Li, Hai-Long; Zhou, Sheng-Mei; Park, Daeui; Jeong, Hyoung Oh; Chung, Hae Young; Yang, Jun-Mo; Meng, Fan-Guo; Hu, Wei-Jiang

    2012-04-01

    Arginine kinase (AK) is a key metabolic enzyme for keeping energy balance in invertebrates. Therefore, regulation of the enzymatic activity and the folding studies of AK from the various invertebrates have been the focus of investigation. We studied the effects of helical structures by using hexafluoroisopropanol (HFIP) on AK folding. Folding kinetic studies showed that the folding rates of the urea-denatured AKs were significantly decelerated after being induced in various concentrations of HFIP. AK lost its activity completely at concentrations greater than 60%. The results indicated that the HFIP-induced helical structures in the denatured state play a negative role in protein folding, and the helical structures induced in 5% (v/v) HFIP act as the most effective barrier against AK taking its native structure. The computational docking simulations (binding energies for -2.19 kcal/mol for AutoDock4.2 and -20.47 kcal/mol for Dock6.3) suggested that HFIP interacts with the several important residues that are predicted by both programs. The excessively pre-organized helical structures not only hampered the folding process, but also ultimately brought about changes in the three-dimensional conformation and biological function of AK.

  15. Helicity and other conservation laws in perfect fluid motion

    Science.gov (United States)

    Serre, Denis

    2018-03-01

    In this review paper, we discuss helicity from a geometrical point of view and see how it applies to the motion of a perfect fluid. We discuss its relation with the Hamiltonian structure, and then its extension to arbitrary space dimensions. We also comment about the existence of additional conservation laws for the Euler equation, and its unlikely integrability in Liouville's sense.

  16. Experiments to measure the gluon helicity distribution in protons

    International Nuclear Information System (INIS)

    Spinka, H.; Beddo, M.E.; Underwood, D.G.

    1993-01-01

    Several experiments are described that could obtain information about the gluon helicity distribution in protons. These experiments include inclusive direct-γ, direct-γ + jet, jet, and jet + jet production with colliding beams of longitudinally-polarized protons. Some rates and kinematics are also discussed

  17. Recent helicity source and power supply improvements in CTX

    International Nuclear Information System (INIS)

    Henins, I.; Knox, S.O.; Jarboe, T.R.; Barnes, C.W.

    1985-01-01

    Since the last CT Symposium, two major changes in CTX have been the introduction of pulse forming networks (PFNs) to drive the coaxial electrode helicity source, and the very recent installation of a larger source with electrode diameters about twice of the previous ones. The power supplies used for CTX have ranged from the simple connection of the capacitor bank across the electrode collector plates (slow mode) to the more sophisticated PFNs, described here, which optimize the energy transfer from the capacitor bank to the magnetic fields of the spheromak. Using the PFNs, the formation and sustainment phase to peak toroidal plasma current lasts longer (approx. =0.7 ms) than in the slow mode (approx. =0.05 ms), thus lowering the peak current that must flow through the electrode surfaces. Also, by supplying the source electrodes with both a square pulse current waveform and a quasi-steady source flux, phi/sub g/, one can generate helicity at a constant source lambda/sub g/ parameter. The use of a larger diameter helicity source will improve the energy efficiency of helicity injection and allow higher source current for the same surface current density because of the larger electrode surface area

  18. Standard and Nonstandard Craniospinal Radiotherapy Using Helical TomoTherapy

    International Nuclear Information System (INIS)

    Parker, William; Brodeur, Marylene; Roberge, David; Freeman, Carolyn

    2010-01-01

    Purpose: To show the advantages of planning and delivering craniospinal radiotherapy with helical TomoTherapy (TomoTherapy Inc., Madison, WI) by presenting 4 cases treated at our institution. Methods and Materials: We first present a standard case of craniospinal irradiation in a patient with recurrent myxopapillary ependymoma (MPE) and follow this with 2 cases requiring differential dosing to multiple target volumes. One of these, a patient with recurrent medulloblastoma, required a lower dose to be delivered to the posterior fossa because the patient had been previously irradiated to the full dose, and the other required concurrent boosts to leptomeningeal metastases as part of his treatment for newly diagnosed MPE. The final case presented is a patient with pronounced scoliosis who required spinal irradiation for recurrent MPE. Results: The four cases presented were planned and treated successfully with Helical Tomotherapy. Conclusions: Helical TomoTherapy delivers continuous arc-based intensity-modulated radiotherapy that gives high conformality and excellent dose homogeneity for the target volumes. Increased healthy tissue sparing is achieved at higher doses albeit at the expense of larger volumes of tissue receiving lower doses. Helical TomoTherapy allows for differential dosing of multiple targets, resulting in very elegant dose distributions. Daily megavoltage computed tomography imaging allows for precision of patient positioning, permitting a reduction in planning margins and increased healthy tissue sparing in comparison with standard techniques.

  19. Helical undulator based on partial redistribution of uniform magnetic field

    Science.gov (United States)

    Balal, N.; Bandurkin, I. V.; Bratman, V. L.; Fedotov, A. E.

    2017-12-01

    A new type of helical undulator based on redistribution of magnetic field of a solenoid by ferromagnetic helix has been proposed and studied both in theory and experiment. Such undulators are very simple and efficient for promising sources of coherent spontaneous THz undulator radiation from dense electron bunches formed in laser-driven photo-injectors.

  20. Helical undulator based on partial redistribution of uniform magnetic field

    Directory of Open Access Journals (Sweden)

    N. Balal

    2017-12-01

    Full Text Available A new type of helical undulator based on redistribution of magnetic field of a solenoid by ferromagnetic helix has been proposed and studied both in theory and experiment. Such undulators are very simple and efficient for promising sources of coherent spontaneous THz undulator radiation from dense electron bunches formed in laser-driven photo-injectors.

  1. Hamiltonian theory of vacuum helical torus lines of magnetic force

    International Nuclear Information System (INIS)

    Gnudi, Giovanni; Hatori, Tadatsugu

    1994-01-01

    For making plasma into equilibrium state, the lines of magnetic force must have magnetic surfaces. However in a helical system, space is divided into the region having magnetic surface structure and the region that does not have it. Accordingly, it is an important basic research for the plasma confinement in a helical system to examine where is the boundary of both regions and how is the large area structure of the lines of magnetic force in the boundary region. The lines of magnetic force can be treated as a Hamilton mechanics system, and it has been proved that the Hamiltonian for the lines of magnetic force can be expressed by a set of canonical variables and the function of time. In this research, the Hamiltonian that describes the lines of magnetic force of helical system torus coordination in vacuum was successfully determined concretely. Next, the development of new linear symplectic integration method was carried out. The important supports for the theory of determining Hamiltonian are Lie transformation and paraxial expansion. The procedure is explained. In Appendix, Lie transformation, Hamiltonian for the lines of magnetic force, magnetic potential, Taylor expansion of the potential, cylindrical limit approximation, helical toroidal potential and integrable model are described. (K.I.)

  2. Transmembrane helices can induce domain formation in crowded model membranes

    NARCIS (Netherlands)

    Domanski, Jan; Marrink, Siewert J.; Schäfer, Lars V.

    We studied compositionally heterogeneous multi-component model membranes comprised of saturated lipids, unsaturated lipids, cholesterol, and a-helical TM protein models using coarse-grained molecular dynamics simulations. Reducing the mismatch between the length of the saturated and unsaturated

  3. Helicity of Solar Active Regions from a Dynamo Model Piyali ...

    Indian Academy of Sciences (India)

    - tions with positive and negative helicities are denoted by '+' and 'o' respectively. A flux eruption takes place in our model whenever the toroidal field at the bottom of the SCZ exceeds a critical value. Whenever an eruption takes place in our ...

  4. Experimental and theoretical studies on a novel helical architecture ...

    Indian Academy of Sciences (India)

    A novel two-dimensional (2D), layered, helical supramolecular architecture constructed via cooperative hydrogen bond and halogen bonds was synthesized and characterized: [(BMBA)₂(TPB)]n (1) [BMBA= 3-bromo-2-methylbenzoic acid, TPB = 1,2,3,4-tetra-(4-pyridyl)-butane]. Density functional theory (DFT) calculations ...

  5. A Lennard-Jones-like perspective on first order transitions in biological helices

    DEFF Research Database (Denmark)

    Oskolkov, Nikolay N.; Bohr, Jakob

    2013-01-01

    Helical structures with Lennard-Jones self-interactions are studied for optimal conformations. For this purpose, their self-energy is analyzed for extrema with respect to the geometric parameters of the helices. It is found that Lennard-Jones helices exhibit a first order phase transition from...

  6. Numerical analysis of fluid flow and heat transfer in a helical ...

    African Journals Online (AJOL)

    Helical channels are widely applied in different application areas. In a converging diverging nozzle, helical channels are mainly used for cooling of its wall. The characteristics of fluid flow and heat transfer inside helical duct for a converging diverging nozzle is not commonly dealt in present literatures. In this paper CFD ...

  7. The generic geometry of helices and their close-packed structures

    DEFF Research Database (Denmark)

    Olsen, Kasper; Bohr, Jakob

    2010-01-01

    The formation of helices is an ubiquitous phenomenon for molecular structures whether they are biological, organic, or inorganic, in nature. Helical structures have geometrical constraints analogous to close packing of three-dimensional crystal structures. For helical packing the geometrical cons...

  8. Whole pelvic helical tomotherapy for locally advanced cervical cancer: technical implementation of IMRT with helical tomothearapy

    International Nuclear Information System (INIS)

    Hsieh, Chen-Hsi; Shueng, Pei-Wei; Wei, Ming-Chow; Lee, Hsing-Yi; Hsiao, Sheng-Mou; Chen, Chien-An; Wang, Li-Ying; Hsieh, Yen-Ping; Tsai, Tung-Hu; Chen, Yu-Jen

    2009-01-01

    To review the experience and to evaluate the treatment plan of using helical tomotherapy (HT) for the treatment of cervical cancer. Between November 1st, 2006 and May 31, 2009, 10 cervical cancer patients histologically confirmed were enrolled. All of the patients received definitive concurrent chemoradiation (CCRT) with whole pelvic HT (WPHT) followed by brachytherapy. During WPHT, all patients were treated with cisplatin, 40 mg/m 2 intravenously weekly. Toxicity of treatment was scored according to the Common Terminology Criteria for Adverse Events v3.0 (CTCAE v3.0). The mean survival was 25 months (range, 3 to 27 months). The actuarial overall survival, disease-free survival, locoregional control and distant metastasis-free rates at 2 years were 67%, 77%, 90% and 88%, respectively. The average of uniformity index and conformal index was 1.06 and 1.19, respectively. One grade 3 of acute toxicity for diarrhea, thrombocytopenia and three grade 3 leucopenia were noted during CCRT. Only one grade 3 of subacute toxicity for thrombocytopenia was noted. There were no grade 3 or 4 subacute toxicities of anemia, leucopenia, genitourinary or gastrointestinal effects. Compared with conventional whole pelvic radiation therapy (WPRT), WPHT decreases the mean dose to rectum, bladder and intestines successfully. HT provides feasible clinical outcomes in locally advanced cervical cancer patients. Long-term follow-up and enroll more locally advanced cervical carcinoma patients by limiting bone marrow radiation dose with WPHT technique is warranted

  9. Pion-nucleon charge-exchange polarization by Gribov Reggeon calculus and the derivative rule

    International Nuclear Information System (INIS)

    Ardill, R.W.B.; Koehler, P.; Moriarty, K.J.M.

    1977-01-01

    The phenomenological consequences of the Gribov Reggeon calculus for the reaction πsup(-)+p→πdeg+n at 6 GeV/c are investigated and the polarization is obtained. The derivative rules is used to calculate the helicity flip amplitude. The results are very encouraging and would seem to indicate that the Gribov Reggeon calculus can be considered a more satisfactory approach to two-body phenomenology than the absorption model

  10. Plasma transport simulation modeling for helical confinement systems

    International Nuclear Information System (INIS)

    Yamazaki, K.; Amano, T.

    1991-08-01

    New empirical and theoretical transport models for helical confinement systems are developed based on the neoclassical transport theory including the effect of radial electric field and multi-helicity magnetic components, and the drift wave turbulence transport for electrostatic and electromagnetic modes, or the anomalous semi-empirical transport. These electron thermal diffusivities are compared with CHS (Compact Helical System) experimental data, which indicates that the central transport coefficient of the ECH plasma agrees with the neoclassical axi-symmetric value and the transport outside the half radius is anomalous. On the other hand, the transport of NBI-heated plasmas is anomalous in the whole plasma region. This anomaly is not explained by the electrostatic drift wave turbulence models in these flat-density-profile discharges. For the detailed prediction of plasma parameters in LHD (Large Helical Device), 3-D(dimensional) equilibrium/1-D transport simulations including empirical or drift wave turbulence models are carried out, which suggests that the global confinement time of LHD is determined mainly by the electron anomalous transport near the plasma edge region rather than the helical ripple transport in the core region. Even if the ripple loss can be eliminated, the increase of the global confinement is 10%. However, the rise in the central ion temperature is more than 20%. If the anomalous loss can be reduced to the half level of the present scaling, like so-called 'H-mode' of the tokamak discharge, the neoclassical ripple loss through the ion channel becomes important even in the plasma core. The 5% radial inward shift of the plasma column with respect to the major radius is effective for improving plasma confinement and raising more than 50% of the fusion product by reducing this neoclassical asymmetric ion transport loss and increasing 10% in the plasma radius. (author)

  11. Plasma transport simulation modelling for helical confinement systems

    International Nuclear Information System (INIS)

    Yamazaki, K.; Amano, T.

    1992-01-01

    New empirical and theoretical transport models for helical confinement systems are developed on the basis of the neoclassical transport theory, including the effect of the radial electric field and of multi-helicity magnetic components as well as the drift wave turbulence transport for electrostatic and electromagnetic modes or the anomalous semi-empirical transport. These electron thermal diffusivities are compared with experimental data from the Compact Helical System which indicate that the central transport coefficient of a plasma with electron cyclotron heating agrees with neoclassical axisymmetric value and the transport outside the half-radius is anomalous. On the other hand, the transport of plasmas with neutral beam injection heating is anomalous in the whole plasma region. This anomaly is not explained by the electrostatic drift wave turbulence models in these discharges with flat density profiles. For a detailed prediction of the plasma parameters in the Large Helical Device (LHD), 3-D equilibrium/1-D transport simulations including empirical or drift wave turbulence models are performed which suggest that the global confinement time of the LHD is determined mainly by the electron anomalous transport in the plasma edge region rather than by the helical ripple transport in the core region. Even if the ripple loss can be eliminated, the increase in global confinement is 10%. However, the rise in the central ion temperature is more than 20%. If the anomalous loss can be reduced to half of the value used in the present scaling, as is the case in the H-mode of tokamak discharges, the neoclassical ripple loss through the ion channel becomes important even in the plasma core. The 5% radial inward shift of the plasma column with respect to the major radius improves the plasma confinement and increases the fusion product by more than 50% by reducing the neoclassical asymmetric ion transport loss and increasing the plasma radius (10%). (author). 32 refs, 7 figs

  12. Overview of results from the Large Helical Device

    International Nuclear Information System (INIS)

    Yamada, H.

    2010-11-01

    The physical understanding of net-current free helical plasmas has progressed in the Large Helical Device (LHD) since the last Fusion Energy Conference in Geneva, 2008. The experimental results from LHD have promoted detailed physical documentation of features specific to net-current-free 3-D helical plasmas as well as complementary to the tokamak approach. The primary heating source is NBI with a heating power of 23 MW, and ECH with 3.7 MW plays an important role in local heating and power modulation in transport studies. The maximum central density has reached 1.2 x 10 21 m -3 due to the formation of an Internal Diffusion Barrier (IDB) at the magnetic field of 2.5 T. The IDB has been maintained for 3 s by refueling with repetitive pellet injection. The plasma with a central ion temperature reaching 5.6 keV exhibits the formation of an Internal Transport Barrier (ITB). The ion thermal diffusivity decreases to the level predicted by neoclassical transport. This ITB is accompanied by spontaneous toroidal rotation and an Impurity Hole which generates an impurity-free core. Impurity Hole is due to a large outward convection of impurities in spite of the negative radial electric field. The magnitude of the Impurity Hole is enhanced in the magnetic configuration with larger helical ripple and for higher Z impurities. Another mechanism to suppress impurity contamination has been identified at the plasma edge with a stochastic magnetic field. A helical system shares common physics issues with tokamaks such as 3-D equilibria, transport in a stochastic magnetic field, plasma response to a Resonant Magnetic Perturbation (RMP), divertor physics, and the role of radial electric field and meso-scale structure. (author)

  13. Examining the Conservation of Kinks in Alpha Helices.

    Directory of Open Access Journals (Sweden)

    Eleanor C Law

    Full Text Available Kinks are a structural feature of alpha-helices and many are known to have functional roles. Kinks have previously tended to be defined in a binary fashion. In this paper we have deliberately moved towards defining them on a continuum, which given the unimodal distribution of kink angles is a better description. From this perspective, we examine the conservation of kinks in proteins. We find that kink angles are not generally a conserved property of homologs, pointing either to their not being functionally critical or to their function being related to conformational flexibility. In the latter case, the different structures of homologs are providing snapshots of different conformations. Sequence identity between homologous helices is informative in terms of kink conservation, but almost equally so is the sequence identity of residues in spatial proximity to the kink. In the specific case of proline, which is known to be prevalent in kinked helices, loss of a proline from a kinked helix often also results in the loss of a kink or reduction in its kink angle. We carried out a study of the seven transmembrane helices in the GPCR family and found that changes in kinks could be related both to subfamilies of GPCRs and also, in a particular subfamily, to the binding of agonists or antagonists. These results suggest conformational change upon receptor activation within the GPCR family. We also found correlation between kink angles in different helices, and the possibility of concerted motion could be investigated further by applying our method to molecular dynamics simulations. These observations reinforce the belief that helix kinks are key, functional, flexible points in structures.

  14. Totally optimal decision rules

    KAUST Repository

    Amin, Talha

    2017-11-22

    Optimality of decision rules (patterns) can be measured in many ways. One of these is referred to as length. Length signifies the number of terms in a decision rule and is optimally minimized. Another, coverage represents the width of a rule’s applicability and generality. As such, it is desirable to maximize coverage. A totally optimal decision rule is a decision rule that has the minimum possible length and the maximum possible coverage. This paper presents a method for determining the presence of totally optimal decision rules for “complete” decision tables (representations of total functions in which different variables can have domains of differing values). Depending on the cardinalities of the domains, we can either guarantee for each tuple of values of the function that totally optimal rules exist for each row of the table (as in the case of total Boolean functions where the cardinalities are equal to 2) or, for each row, we can find a tuple of values of the function for which totally optimal rules do not exist for this row.

  15. Totally optimal decision rules

    KAUST Repository

    Amin, Talha M.; Moshkov, Mikhail

    2017-01-01

    Optimality of decision rules (patterns) can be measured in many ways. One of these is referred to as length. Length signifies the number of terms in a decision rule and is optimally minimized. Another, coverage represents the width of a rule’s applicability and generality. As such, it is desirable to maximize coverage. A totally optimal decision rule is a decision rule that has the minimum possible length and the maximum possible coverage. This paper presents a method for determining the presence of totally optimal decision rules for “complete” decision tables (representations of total functions in which different variables can have domains of differing values). Depending on the cardinalities of the domains, we can either guarantee for each tuple of values of the function that totally optimal rules exist for each row of the table (as in the case of total Boolean functions where the cardinalities are equal to 2) or, for each row, we can find a tuple of values of the function for which totally optimal rules do not exist for this row.

  16. The INCOTERMS rules and their importance

    Directory of Open Access Journals (Sweden)

    Anca LAZĂR

    2011-06-01

    Full Text Available The content INCOTERMS are a set of rules that determine the rights and obligations of the international sales contract, selecting a rule of interpretation of commercial terms INCOTERMS, progress is the result of negotiation between the parties and expresses the ratio of these economic forces. In relation to the obligations of the parties to an international sales contract are several different types of contracts covered by the clause. To define the main rules INCOTERMS was considered as a starting point delivery of goods, establishment of the seller and the buyer2, the rules concerning the obligations of each party that are grouped into ten items with identical titles for all the rules. Due to significant developments in international trade, for making available to retailers in the interpretation of the rules commonly used trade terms in international trade, the International Chamber of Commerce in Paris draw a set of delivery conditions for their interpretation in international sales, rules that were in international trade practice some habits, but who were not of equal significance to traders in different countries.

  17. The OZI rule and nucleons

    International Nuclear Information System (INIS)

    Lipkin, H.J.

    1991-11-01

    The title of this lecture series raises two questions: (1) what is the OZI rule? (2) what is a nucleon. In the lectures both questions were addressed in parallel and the material moved back and forth between them. In a written version it seems more appropriate to treat the two question separately, begining with trying to understand the structure of the nucleon. Experimental evidence for the symmetry and quark structure of hadrons is reviewed with a historical introduction and updated by presenting constituent quark model relation for hadron masses and magnetic moments.Three definitions of the OZI rule are presented, all which forbid decay like φ->ρπ but making different selection rules for more complicate reactions. All suffer from the higer order paradox that a forbidden process can take place via two-step transition in which each step is allowed; e.g. φ-> KK-bar -> ρπ. No prescription is given for estimating the strength of forbidden processes. The role of cancellations between different higer order diagrams is discussed. (author)

  18. Comparative analysis of business rules and business process modeling languages

    Directory of Open Access Journals (Sweden)

    Audrius Rima

    2013-03-01

    Full Text Available During developing an information system is important to create clear models and choose suitable modeling languages. The article analyzes the SRML, SBVR, PRR, SWRL, OCL rules specifying language and UML, DFD, CPN, EPC and IDEF3 BPMN business process modeling language. The article presents business rules and business process modeling languages theoretical comparison. The article according to selected modeling aspects of the comparison between different business process modeling languages ​​and business rules representation languages sets. Also, it is selected the best fit of language set for three layer framework for business rule based software modeling.

  19. Following the Rules.

    Science.gov (United States)

    Katz, Anne

    2016-05-01

    I am getting better at following the rules as I grow older, although I still bristle at many of them. I was a typical rebellious teenager; no one understood me, David Bowie was my idol, and, one day, my generation was going to change the world. Now I really want people to understand me: David Bowie remains one of my favorite singers and, yes, my generation has changed the world, and not necessarily for the better. Growing up means that you have to make the rules, not just follow those set by others, and, at times, having rules makes a lot of sense.
.

  20. Do Fiscal Rules Matter?

    DEFF Research Database (Denmark)

    Grembi, Veronica; Nannicini, Tommaso; Troiano, Ugo

    2016-01-01

    , the central government imposed fiscal rules on municipal governments, and in 2001 relaxed them below 5,000 inhabitants. We exploit the before/after and discontinuous policy variation, and show that relaxing fiscal rules increases deficits and lowers taxes. The effect is larger if the mayor can be reelected......Fiscal rules are laws aimed at reducing the incentive to accumulate debt, and many countries adopt them to discipline local governments. Yet, their effectiveness is disputed because of commitment and enforcement problems. We study their impact applying a quasi-experimental design in Italy. In 1999...

  1. Formation and sustainment of a very low aspect ratio tokamak using coaxial helicity injection (the Helicity Injected Torus [HIT] experiment)

    International Nuclear Information System (INIS)

    Jarboe, T.R.; Nelson, B.A.

    1992-01-01

    In the paper we will detail the progress of the HIT experiment construction, including the following components: preliminary data and interpretation; diagnostic systems; vacuum vessel and pumping system; helicity source and power supplies; toroidal field coil and power supply; data acquisition system; collaboration with general atomics, with a brief summary given on each

  2. Automatic inference of indexing rules for MEDLINE

    Directory of Open Access Journals (Sweden)

    Shooshan Sonya E

    2008-11-01

    Full Text Available Abstract Background: Indexing is a crucial step in any information retrieval system. In MEDLINE, a widely used database of the biomedical literature, the indexing process involves the selection of Medical Subject Headings in order to describe the subject matter of articles. The need for automatic tools to assist MEDLINE indexers in this task is growing with the increasing number of publications being added to MEDLINE. Methods: In this paper, we describe the use and the customization of Inductive Logic Programming (ILP to infer indexing rules that may be used to produce automatic indexing recommendations for MEDLINE indexers. Results: Our results show that this original ILP-based approach outperforms manual rules when they exist. In addition, the use of ILP rules also improves the overall performance of the Medical Text Indexer (MTI, a system producing automatic indexing recommendations for MEDLINE. Conclusion: We expect the sets of ILP rules obtained in this experiment to be integrated into MTI.

  3. Self/anti-self charge conjugate states in the helicity basis

    International Nuclear Information System (INIS)

    Dvoeglazov, Valeriy V.

    2013-01-01

    We construct self/anti-self charge conjugate (Majorana-like) states for the (1/2,0)⊕(0,1/2) representation of the Lorentz group, and their analogs for higher spins within the quantum field theory. The problem of the basis rotations and that of the selection of phases in the Dirac-like and Majorana-like field operators are considered. The discrete symmetries properties (P, C, T) are studied. Particular attention has been paid to the question of (anti)commutation of the Charge conjugation operator and the Parity in the helicity basis. Dynamical equations have also been presented. In the (1/2,0)⊕(0,1/2) representation they obey the Dirac-like equation with eight components, which has been first introduced by Markov. Thus, the Fock space for corresponding quantum fields is doubled (as shown by Ziino). The chirality and the helicity (two concepts which are frequently confused in the literature) for Dirac and Majorana states have been discussed

  4. An experimental investigation of pneumatic swirl flow induced by a three lobed helical pipe

    International Nuclear Information System (INIS)

    Fokeer, S.; Lowndes, I.; Kingman, S.

    2009-01-01

    This paper presents a discussion of the results and conclusions drawn from a series of experiments conducted to investigate the swirl flow that are generated by a three lobed helical pipe mounted within a laboratory scale pneumatic conveying rig. The experiments employed Laser Doppler Anemometry (LDA) to quantify the strength of the induced vortex formations and the decay rates of the observed downstream swirl flows over a range of Reynolds number in the turbulent regime. Instantaneous point velocity measurements were resolved in three directions across regular measurement grids transcribed across parallel planes located at four distances downstream of the swirl inducing pipe section. The equivalent axial, radial and tangential velocities were subsequently computed at these grids points. The degree of swirl measured across each measurement plane was expressed in terms of a defined swirl number. It was concluded that the three lobed helical pipe gave rise to a wall jet type of swirl whose rate of observed downstream decay is related to the Reynolds number of the upstream flow and the distance downstream of the swirl pipe. The decay rates for the swirl flows were found to be inversely proportional to the Reynolds number of the upstream flow. The swirl pipe was observed to create a redistribution of the downstream velocity field from axial to tangential, accompanied by a transfer of axial to angular momentum. The findings of this paper are believed to improve understanding to assist the selective use of swirl flow within lean phase particles pneumatic transport systems.

  5. An experimental investigation of pneumatic swirl flow induced by a three lobed helical pipe

    Energy Technology Data Exchange (ETDEWEB)

    Fokeer, S. [Department of Aeronautical and Automotive Engineering, University of Loughborough LE11 3TU (United Kingdom)], E-mail: S.Fokeer@lboro.ac.uk; Lowndes, I.; Kingman, S. [Division of Process and Environmental Engineering, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2009-04-15

    This paper presents a discussion of the results and conclusions drawn from a series of experiments conducted to investigate the swirl flow that are generated by a three lobed helical pipe mounted within a laboratory scale pneumatic conveying rig. The experiments employed Laser Doppler Anemometry (LDA) to quantify the strength of the induced vortex formations and the decay rates of the observed downstream swirl flows over a range of Reynolds number in the turbulent regime. Instantaneous point velocity measurements were resolved in three directions across regular measurement grids transcribed across parallel planes located at four distances downstream of the swirl inducing pipe section. The equivalent axial, radial and tangential velocities were subsequently computed at these grids points. The degree of swirl measured across each measurement plane was expressed in terms of a defined swirl number. It was concluded that the three lobed helical pipe gave rise to a wall jet type of swirl whose rate of observed downstream decay is related to the Reynolds number of the upstream flow and the distance downstream of the swirl pipe. The decay rates for the swirl flows were found to be inversely proportional to the Reynolds number of the upstream flow. The swirl pipe was observed to create a redistribution of the downstream velocity field from axial to tangential, accompanied by a transfer of axial to angular momentum. The findings of this paper are believed to improve understanding to assist the selective use of swirl flow within lean phase particles pneumatic transport systems.

  6. Comparison of helical computed tomography and ultrasonography in diagnosis of acute appendicitis

    International Nuclear Information System (INIS)

    Nafees, M.; Abbas, G.; Sarwar, S.

    2010-01-01

    The objective of study is to compare the diagnostic accuracy of helical computed tomography and ultrasonography in acute appendicitis using histopathology as gold standard. Thirty cases of clinically suspected acute appendicitis were included in the study selected on non probability convenience sampling technique. Computed tomography and graded compression ultrasonography of right lower quadrant of abdomen were conducted and results compared with histopathological findings. Amongst 30 patients who underwent computed tomography and graded compression ultrasonography examinations of right lower quadrant for diagnosis of acute appendicitis, on computed tomography 19 were diagnosed with acute appendicitis, 10 were diagnosed as not having the disease and 01 patient diagnosed as not having appendicitis on computed tomography did not improve clinically, was operated upon and histopathology proved it as acute appendicitis. While on graded compression ultrasonography 15 were diagnosed with acute appendicitis, 11 were diagnosed as not having the disease and 04 patients diagnosed as not having appendicitis on ultrasonography, did not improve clinically, were operated upon and histopathology proved it as acute appendicitis. This showed that CT scan has sensitivity of 95%, specificity 100%, positive predictive value 100%, negative predictive value 90.91% and overall accuracy of 96.67% while ultrasonography has sensitivity of 78.9%, specificity 100%, positive predictive value 100%, negative predictive value 73.33% and overall accuracy of 86.67%. We concluded that Helical computed tomography is highly accurate in diagnosing acute appendicitis as compared to ultrasonography and it helps to reduce negative appendectomy rate. (author)

  7. Staff rules and regulations

    CERN Multimedia

    HR Department

    2007-01-01

    The 11th edition of the Staff Rules and Regulations, dated 1 January 2007, adopted by the Council and the Finance Committee in December 2006, is currently being distributed to departmental secretariats. The Staff Rules and Regulations, together with a summary of the main modifications made, will be available, as from next week, on the Human Resources Department's intranet site: http://cern.ch/hr-web/internal/admin_services/rules/default.asp The main changes made to the Staff Rules and Regulations stem from the five-yearly review of employment conditions of members of the personnel. The changes notably relate to: the categories of members of the personnel (e.g. removal of the local staff category); the careers structure and the merit recognition system; the non-residence, installation and re-installation allowances; the definition of family, family allowances and family-related leave; recognition of partnerships; education fees. The administrative circulars, some of which are being revised following the ...

  8. Data breaches. Final rule.

    Science.gov (United States)

    2008-04-11

    This document adopts, without change, the interim final rule that was published in the Federal Register on June 22, 2007, addressing data breaches of sensitive personal information that is processed or maintained by the Department of Veterans Affairs (VA). This final rule implements certain provisions of the Veterans Benefits, Health Care, and Information Technology Act of 2006. The regulations prescribe the mechanisms for taking action in response to a data breach of sensitive personal information.

  9. Mechanisms of rule acquisition and rule following in inductive reasoning.

    Science.gov (United States)

    Crescentini, Cristiano; Seyed-Allaei, Shima; De Pisapia, Nicola; Jovicich, Jorge; Amati, Daniele; Shallice, Tim

    2011-05-25

    Despite the recent interest in the neuroanatomy of inductive reasoning processes, the regional specificity within prefrontal cortex (PFC) for the different mechanisms involved in induction tasks remains to be determined. In this study, we used fMRI to investigate the contribution of PFC regions to rule acquisition (rule search and rule discovery) and rule following. Twenty-six healthy young adult participants were presented with a series of images of cards, each consisting of a set of circles numbered in sequence with one colored blue. Participants had to predict the position of the blue circle on the next card. The rules that had to be acquired pertained to the relationship among succeeding stimuli. Responses given by subjects were categorized in a series of phases either tapping rule acquisition (responses given up to and including rule discovery) or rule following (correct responses after rule acquisition). Mid-dorsolateral PFC (mid-DLPFC) was active during rule search and remained active until successful rule acquisition. By contrast, rule following was associated with activation in temporal, motor, and medial/anterior prefrontal cortex. Moreover, frontopolar cortex (FPC) was active throughout the rule acquisition and rule following phases before a rule became familiar. We attributed activation in mid-DLPFC to hypothesis generation and in FPC to integration of multiple separate inferences. The present study provides evidence that brain activation during inductive reasoning involves a complex network of frontal processes and that different subregions respond during rule acquisition and rule following phases.

  10. The management of helical rim keloids with excision, split thickness skin graft and intralesional triamcinolone acetonide

    Directory of Open Access Journals (Sweden)

    Ibrahim Abdul Rasheed

    2014-01-01

    Full Text Available Keloids of the helical rim are disfiguring. A cosmetically acceptable reconstruction is difficult especially in moderate to large sized lesions because the helical rim is a 3-dimensional structure with curved and thin cartilage. We report our experience in the management of moderate (4-10 cm and large (>10 cm helical rim keloids in five patients. Six helical rim keloids were reconstructed. There were four moderate (4-10 cm and two large (>10 cm helical rim keloids. Four were on the right helix and two on the left helix. One patient had bilateral helical rim keloids. The follow-up period ranged from 6 months to 4 years. No secondary surgical revision was required to improve the contour of the reconstructed helical rim. The aesthetic results were satisfactory in all the patients.

  11. Investigation of the OZI selection rule for connected quark diagrams in hadronic processes: 3. Diffractive φ and ω production in pN collisions at 70 GeV

    International Nuclear Information System (INIS)

    1996-01-01

    The ratio between the cross sections for the diffractive production of pφ and pω systems in pN collisions at Ep=70 GeV is determined by using data from the SPHINX detector. A significant violation of the OZI rule in proton-induced transitions is observed

  12. Form coefficient of helical toroidal solenoids

    International Nuclear Information System (INIS)

    Amelin, V.Z.; Kunchenko, V.B.

    1982-01-01

    For toroidal solenoids with continuous spiral coil, winded according to the laws of equiinclined and simple cylindrical spirals with homogeneous, linearly increasing to the coil periphery and ''Bitter'' distribution of current density, the analytical expressions for the dependence between capacity consumed and generated magnetic field, expressions for coefficients of form similar to Fabry coefficient for cylindrical solenoids are obtained and dependence of the form coefficient and relative volume of solenoid conductor on the number of revolutions of screw line per one circumvention over the large torus radius is also investigated. Analytical expressions of form coefficients and graphical material permit to select the optimum geometry as to capacity consumed both for spiral (including ''force-free'') and conventional toroidal solenoids of magnetic systems in thermonulear installations

  13. A generalization of Hamilton's rule--love others how much?

    Science.gov (United States)

    Alger, Ingela; Weibull, Jörgen W

    2012-04-21

    According to Hamilton's (1964a, b) rule, a costly action will be undertaken if its fitness cost to the actor falls short of the discounted benefit to the recipient, where the discount factor is Wright's index of relatedness between the two. We propose a generalization of this rule, and show that if evolution operates at the level of behavior rules, rather than directly at the level of actions, evolution will select behavior rules that induce a degree of cooperation that may differ from that predicted by Hamilton's rule as applied to actions. In social dilemmas there will be less (more) cooperation than under Hamilton's rule if the actions are strategic substitutes (complements). Our approach is based on natural selection, defined in terms of personal (direct) fitness, and applies to a wide range of pairwise interactions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Anti-plasmodial action of de novo-designed, cationic, lysine-branched, amphipathic, helical peptides

    Directory of Open Access Journals (Sweden)

    Kaushik Naveen K

    2012-08-01

    Full Text Available Abstract Background A lack of vaccine and rampant drug resistance demands new anti-malarials. Methods In vitro blood stage anti-plasmodial properties of several de novo-designed, chemically synthesized, cationic, amphipathic, helical, antibiotic peptides were examined against Plasmodium falciparum using SYBR Green assay. Mechanistic details of anti-plasmodial action were examined by optical/fluorescence microscopy and FACS analysis. Results Unlike the monomeric decapeptides {(Ac-GXRKXHKXWA-NH2 (X = F,ΔF (Fm, ΔFm IC50 >100 μM}, the lysine-branched,dimeric versions showed far greater potency {IC50 (μM Fd 1.5 , ΔFd 1.39}. The more helical and proteolytically stable ΔFd was studied for mechanistic details. ΔFq, a K-K2 dendrimer of ΔFm and (ΔFm2 a linear dimer of ΔFm showed IC50 (μM of 0.25 and 2.4 respectively. The healthy/infected red cell selectivity indices were >35 (ΔFd, >20 (ΔFm2 and 10 (ΔFq. FITC-ΔFd showed rapid and selective accumulation in parasitized red cells. Overlaying DAPI and FITC florescence suggested that ΔFd binds DNA. Trophozoites and schizonts incubated with ΔFd (2.5 μM egressed anomalously and Band-3 immunostaining revealed them not to be associated with RBC membrane. Prematurely egressed merozoites from peptide-treated cultures were found to be invasion incompetent. Conclusion Good selectivity (>35, good resistance index (1.1 and low cytotoxicity indicate the promise of ΔFd against malaria.

  15. Effects of Magnetic and Kinetic Helicities on the Growth of Magnetic Fields in Laminar and Turbulent Flows by Helical Fourier Decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Linkmann, Moritz; Sahoo, Ganapati; Biferale, Luca [Department of Physics and INFN, University of Rome Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Rome (Italy); McKay, Mairi; Berera, Arjun [School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, EH9 3FD, Edinburgh (United Kingdom)

    2017-02-10

    We present a numerical and analytical study of incompressible homogeneous conducting fluids using a helical Fourier representation. We analytically study both small- and large-scale dynamo properties, as well as the inverse cascade of magnetic helicity, in the most general minimal subset of interacting velocity and magnetic fields on a closed Fourier triad. We mainly focus on the dependency of magnetic field growth as a function of the distribution of kinetic and magnetic helicities among the three interacting wavenumbers. By combining direct numerical simulations of the full magnetohydrodynamics equations with the helical Fourier decomposition, we numerically confirm that in the kinematic dynamo regime the system develops a large-scale magnetic helicity with opposite sign compared to the small-scale kinetic helicity, a sort of triad-by-triad α -effect in Fourier space. Concerning the small-scale perturbations, we predict theoretically and confirm numerically that the largest instability is achived for the magnetic component with the same helicity of the flow, in agreement with the Stretch–Twist–Fold mechanism. Vice versa, in the presence of Lorentz feedback on the velocity, we find that the inverse cascade of magnetic helicity is mostly local if magnetic and kinetic helicities have opposite signs, while it is more nonlocal and more intense if they have the same sign, as predicted by the analytical approach. Our analytical and numerical results further demonstrate the potential of the helical Fourier decomposition to elucidate the entangled dynamics of magnetic and kinetic helicities both in fully developed turbulence and in laminar flows.

  16. Non-inductive current drive via helicity injection by Alfven waves in low-aspect-ratio tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Cuperman, S.; Bruma, C.; Komoshvili, K. [Tel Aviv Univ. (Israel). Sackler Faculty of Exact Sciences

    1996-08-01

    A theoretical investigation of radio-frequency (RF) current drive via helicity injection in low aspect ratio tokamaks is carried out. A current-carrying cylindrical plasma surrounded by a helical sheet-current antenna and situated inside a perfectly conducting shell is considered. Toroidal features of low-aspect-ratio tokamaks are simulated by incorporating the following effects: (i) arbitrarily small aspect ratio, R{sub O}/a ``identical to`` 1/{epsilon}; (ii) strongly sheared equilibrium magnetic field; and (iii) relatively large poloidal component of the equilibrium magnetic field. This study concentrates on the Alfven continuum, i.e. the case in which the wave frequency satisfies the condition {l_brace}{omega}{sub Alf}({tau}){r_brace}{sub min}{r_brace} {<=} {omega} {<=} {l_brace}{omega}{sub Alf}({tau}){r_brace}{sub max}, where {omega}{sub Alf}({tau}) ``identical to`` {omega}{sub Alf}[n({tau}), B{sub O}({tau})] is an eigenfrequency of the shear Alfven wave (SAW). Thus, using low-{beta} magnetohydrodynamics, the wave equation with correct boundary (matching) conditions is solved, the RF field components are found, and subsequently current drive, power deposition and efficiency are computed. The results of our investigation clearly demonstrate the possibility of generation of RF-driven currents via helicity injection by Alfven waves in low-aspect-ratio tokamaks, in the SAW mode. A special algorithm is developed that enables one to select the antenna parameters providing optimal current drive efficiency. (Author).

  17. On the diffusion of alpha-helical proteins in solvents

    Science.gov (United States)

    Barredo, Wilson I.; Bornales, Jinky B.; Bernido, Christopher C.; Aringa, Henry P.

    2015-01-01

    The winding probability function for a biopolymer diffusing in a crowded cell is obtained with the drift coefficient f(s) involving Bessel functions of general form f(s) = kJ2p+1 (νs). The variable s is the length along the chain and ν is a constant which can be used to simulate the frequency of appearance of a certain type of amino acid. Application of a particular case p = 3 to protein chains is carried out for different alpha helical proteins found in the Protein Data Bank (PDB). Analysis of our results leads us to an empirical formula that can be used to conveniently predict k/D and ν, where D is the diffusion coefficient of various α-helical proteins in solvents.

  18. Study on reinforced concrete beams with helical transverse reinforcement

    Science.gov (United States)

    Kaarthik Krishna, N.; Sandeep, S.; Mini, K. M.

    2018-02-01

    In a Reinforced Concrete (R.C) structure, major reinforcement is used for taking up tensile stresses acting on the structure due to applied loading. The present paper reports the behavior of reinforced concrete beams with helical reinforcement (transverse reinforcement) subjected to monotonous loading by 3-point flexure test. The results were compared with identically similar reinforced concrete beams with rectangular stirrups. During the test crack evolution, load carrying capacity and deflection of the beams were monitored, analyzed and compared. Test results indicate that the use of helical reinforcement provides enhanced load carrying capacity and a lower deflection proving to be more ductile, clearly indicating the advantage in carrying horizontal loads. An analysis was also carried out using ANSYS software in order to compare the test results of both the beams.

  19. Production of linear polarization by segmentation of helical undulator

    International Nuclear Information System (INIS)

    Tanaka, T.; Kitamura, H.

    2002-01-01

    A simple scheme to obtain linearly polarized radiation (LPR) with a segmented undulator is proposed. The undulator is composed of several segments each of which forms a helical undulator and has helicity opposite to those of adjacent segments. Due to coherent sum of radiation, the circularly polarized component is canceled out resulting in production of LPR without any higher harmonics. The radiation from the proposed device is investigated analytically, which shows that a high degree of linear polarization is obtained in spite of a finite beam emittance and angular acceptance of optics, if a sufficiently large number of segments and an adequate photon energy are chosen. Results of calculation to investigate practical performances of the proposed device are presented

  20. Helical Root Buckling: A Transient Mechanism for Stiff Interface Penetration

    Science.gov (United States)

    Silverberg, Jesse; Noar, Roslyn; Packer, Michael; Harrison, Maria; Cohen, Itai; Henley, Chris; Gerbode, Sharon

    2011-03-01

    Tilling in agriculture is commonly used to loosen the topmost layer of soil and promote healthy plant growth. As roots navigate this mechanically heterogeneous environment, they encounter interfaces between the compliant soil and the underlying compacted soil. Inspired by this problem, we used 3D time-lapse imaging of Medicago Truncatula plants to study root growth in two-layered transparent hydrogels. The layers are mechanically distinct; the top layer is more compliant than the bottom. We observe that the roots form a transient helical structure as they attempt to penetrate the bi-layer interface. Interpreting this phenotype as a form of buckling due to root elongation, we measured the helix size as a function of the surrounding gel modulus. Our measurements show that by twisting the root tip during growth, the helical structure recruits the surrounding medium for an enhanced penetration force allowing the plants access to the lower layer of gel.

  1. A rotating helical sealing joint capable of partially melting

    International Nuclear Information System (INIS)

    Martin, Jean; Ollier, J.-L.; Petit, Paul.

    1973-01-01

    A coagulated rotating helical joint providing gas and liquid tightness along a rotating shaft, comprising: a metal sleeve connected to the wall through which passes the rotating sleeve, an intermediate sleeve made of a fusible material, inert with respect to the fluid to be sealingly retained, and finally the rotating shaft provided with an engraved helical thread in register with the intermediate sleeve. Means are provided for regulating the intermediate sleeve temperature so that a thin melted film is formed on said intermediate sleeve when in contact with the rotating threaded shaft. This can be applied in the nuclear industry, including cases when the intermediate sleeve is constituted by the fluid itself, then in the solid state [fr

  2. Finite-temperature effects in helical quantum turbulence

    Science.gov (United States)

    Clark Di Leoni, Patricio; Mininni, Pablo D.; Brachet, Marc E.

    2018-04-01

    We perform a study of the evolution of helical quantum turbulence at different temperatures by solving numerically the Gross-Pitaevskii and the stochastic Ginzburg-Landau equations, using up to 40963 grid points with a pseudospectral method. We show that for temperatures close to the critical one, the fluid described by these equations can act as a classical viscous flow, with the decay of the incompressible kinetic energy and the helicity becoming exponential. The transition from this behavior to the one observed at zero temperature is smooth as a function of temperature. Moreover, the presence of strong thermal effects can inhibit the development of a proper turbulent cascade. We provide Ansätze for the effective viscosity and friction as a function of the temperature.

  3. Helicity coherence in binary neutron star mergers and nonlinear feedback

    Science.gov (United States)

    Chatelain, Amélie; Volpe, Cristina

    2017-02-01

    Neutrino flavor conversion studies based on astrophysical environments usually implement neutrino mixings, neutrino interactions with matter, and neutrino self-interactions. In anisotropic media, the most general mean-field treatment includes neutrino mass contributions as well, which introduce a coupling between neutrinos and antineutrinos termed helicity or spin coherence. We discuss resonance conditions for helicity coherence for Dirac and Majorana neutrinos. We explore the role of these mean-field contributions on flavor evolution in the context of a binary neutron star merger remnant. We find that resonance conditions can be satisfied in neutron star merger scenarios while adiabaticity is not sufficient for efficient flavor conversion. We analyze our numerical findings by discussing general conditions to have multiple Mikheyev-Smirnov-Wolfenstein-like resonances, in the presence of nonlinear feedback, in astrophysical environments.

  4. A delivery transfer function (DTF) analysis for helical tomotherapy

    International Nuclear Information System (INIS)

    Kissick, Michael W; Mackie, Thomas Rockwell; Jeraj, Robert

    2007-01-01

    The previous theoretical work of a delivery transfer function (DTF) in radiotherapy is expanded to include the unique intensity modulation method of helical tomotherapy. In addition to the collimation of each beamlet, and the Gaussian scatter convolution spreading of the dose that other radiotherapy units have, helical tomotherapy uses 51 small arcs of varying lengths to adjust the intensity. The blurring from these arcs is not taken into account during treatment planning. A theoretical DTF is constructed, and a calculation is performed which includes this unique source motion in relation to the other DTF components. Various typical delivery parameters are used to generate resolution maps for a constant intensity projection. Near the isocenter, the transverse (to a given beam direction) blurring is small but at larger radii (>6 cm), the source blurring dominates over leaf size. For most clinical situations, this inherent source motion blurring is expected to be negligible

  5. Small-x Asymptotics of the Quark Helicity Distribution.

    Science.gov (United States)

    Kovchegov, Yuri V; Pitonyak, Daniel; Sievert, Matthew D

    2017-02-03

    We construct a numerical solution of the small-x evolution equations derived in our recent work [J. High Energy Phys. 01 (2016) 072.JHEPFG1029-847910.1007/JHEP01(2016)072] for the (anti)quark transverse momentum dependent helicity TMDs and parton distribution functions (PDFs) as well as the g_{1} structure function. We focus on the case of large N_{c}, where one finds a closed set of equations. Employing the extracted intercept, we are able to predict directly from theory the behavior of the quark helicity PDFs at small x, which should have important phenomenological consequences. We also give an estimate of how much of the proton's spin carried by the quarks may be at small x and what impact this has on the spin puzzle.

  6. Compensating Faraday Depolarization by Magnetic Helicity in the Solar Corona

    Energy Technology Data Exchange (ETDEWEB)

    Brandenburg, Axel; Ashurova, Mohira B. [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303 (United States); Jabbari, Sarah, E-mail: brandenb@nordita.org [School of Mathematical Sciences and Monash Centre for Astrophysics, Monash University, Clayton, VIC 3800 (Australia)

    2017-08-20

    A turbulent dynamo in spherical geometry with an outer corona is simulated to study the sign of magnetic helicity in the outer parts. In agreement with earlier studies, the sign in the outer corona is found to be opposite to that inside the dynamo. Line-of-sight observations of polarized emission are synthesized to explore the feasibility of using the local reduction of Faraday depolarization to infer the sign of helicity of magnetic fields in the solar corona. This approach was previously identified as an observational diagnostic in the context of galactic magnetic fields. Based on our simulations, we show that this method can be successful in the solar context if sufficient statistics are gathered by using averages over ring segments in the corona separately for the regions north and south of the solar equator.

  7. Analysis of Eyring-Powell Fluid in Helical Screw Rheometer

    Directory of Open Access Journals (Sweden)

    A. M. Siddiqui

    2014-01-01

    Full Text Available This paper aims to study the flow of an incompressible, isothermal Eyring-Powell fluid in a helical screw rheometer. The complicated geometry of the helical screw rheometer is simplified by “unwrapping or flattening” the channel, lands, and the outside rotating barrel, assuming the width of the channel is larger as compared to the depth. The developed second order nonlinear differential equations are solved by using Adomian decomposition method. Analytical expressions are obtained for the velocity profiles, shear stresses, shear at wall, force exerted on fluid, volume flow rates, and average velocity. The effect of non-Newtonian parameters, pressure gradients, and flight angle on the velocity profiles is noticed with the help of graphical representation. The observation confirmed the vital role of involved parameters during the extrusion process.

  8. A 3D printed helical antenna with integrated lens

    KAUST Repository

    Farooqui, Muhammad Fahad

    2015-10-26

    A novel antenna configuration comprising a helical antenna with an integrated lens is demonstrated in this work. The antenna is manufactured by a unique combination of 3D printing of plastic material (ABS) and inkjet printing of silver nano-particle based metallic ink. The integration of lens enhances the gain by around 7 dB giving a peak gain of about 16.4 dBi at 9.4 GHz. The helical antenna operates in the end-fire mode and radiates a left-hand circularly polarized (LHCP) pattern. The 3-dB axial ratio (AR) bandwidth of the antenna with lens is 3.2 %. Due to integration of lens and fully printed processing, this antenna configuration offers high gain performance and requires low cost for manufacturing.

  9. Five Rules for the Evolution of Cooperation

    Science.gov (United States)

    Nowak, Martin A.

    2006-12-01

    Cooperation is needed for evolution to construct new levels of organization. Genomes, cells, multicellular organisms, social insects, and human society are all based on cooperation. Cooperation means that selfish replicators forgo some of their reproductive potential to help one another. But natural selection implies competition and therefore opposes cooperation unless a specific mechanism is at work. Here I discuss five mechanisms for the evolution of cooperation: kin selection, direct reciprocity, indirect reciprocity, network reciprocity, and group selection. For each mechanism, a simple rule is derived that specifies whether natural selection can lead to cooperation.

  10. Pair production of helicity-flipped neutrinos in supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Perez, A. (NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Box 500, Batavia, Illinois 60510-0500 (USA) Departamento de Fisica Teorica, Universidad de Valencia, 46100 Burjassot (Valencia) (Spain)); Gandhi, R. (Department of Physics and Astronomy, University of Arizona, Tucson, AZ (USA))

    1990-04-15

    We calculate the emissivity for the pair production of helicity-flipped neutrinos, in a way that can be used in supernova calculations. We also present some simple estimates which show that such a process can act as an efficient energy-loss mechanism in the shocked supernova core, and we use this fact to estimate neutrino mass limits from SN 1987A neutrino observations.

  11. Pair production of helicity-flipped neutrinos in supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Perez, A.; Gandhi, R.

    1989-07-03

    We calculate the emissivity for the pair production of helicity-flipped neutrinos, in a way that can be used in supernova calculations. We also present some simple estimates which show that such processes can act as an efficient energy-loss mechanism in the shocked supernova core, and we use this fact to extract neutrino mass limits from SN1987A neutrino observations. 24 refs., 2 figs.

  12. Formation of helical electron beams by electrostatic pumping

    International Nuclear Information System (INIS)

    Barroso, J.J.; Spassovsky, L.P.; Stellati, C.

    1993-01-01

    A non-adiabatic gun for a 35 GHz, 100 kw gyrotron is presented. A 50 kV, 10 A laminar helical electron beam has been achieved with a perpendicular to parallel velocity ratio of 1.9. A non-adiabatic change of the pumping electric field is used to impart rotational velocity to the beam particles which are extracted at the cathode surface in a direction parallel to the guiding magnetic field. (author)

  13. Colonic metastasis from renal cell carcinoma: helical-CT demonstration

    International Nuclear Information System (INIS)

    Diaz-Candamio, M.J.; Pombo, S.; Pombo, F.

    2000-01-01

    Clinically evident colonic metastasis from renal cell carcinoma (RCC) is rare. In the present study a hypervascular sigmoid mass was demonstrated on arterial-phase helical CT using a water enema in a patient who had suffered left nephrectomy 8 years previously for RCC. The intense and early enhancement of the lesion suggested the possibility of a solitary colonic metastasis from RCC, a diagnosis which was pathologically confirmed. (orig.)

  14. FITTING HELICAL SNAKE AND ROTATOR FIELD STRENGTH MEASUREMENTS IN RHIC

    International Nuclear Information System (INIS)

    RANJBAR, V.; LUCCIO, A.U.; MACKAY, W.W.; TSOUPAS, N.

    2001-01-01

    We examined recent multi-pole measurements for the helical snakes and rotators in RHIC to generate a full field map. Since multi-pole measurements yield real field values for B, field components we developed a unique technique to evaluate the full fields using a traditional finite element analysis software [1]. From these measurements we employed SNIG [2] to generate orbit and Spin plots. From orbit values we generated a transfer matrix for the first snake

  15. Alternating-current ohmic heating in a helical stellarator

    International Nuclear Information System (INIS)

    Funato, Yasuyuki; Kitajima, Sumio; Watanabe, Hiroshige

    1984-01-01

    A toroidal plasma is generated successively by an alternating-current discharge in a helical or non-planar torus, and is confined quasi-stationarily by a longitudinal magnetic field with a high rotational transform angle. The particle confinement time obtained experimentally is estimated to be 3-10 ms, which is compared with theoretical values for this system, and is much larger than the time of pulse interval of the plasma production. (author)

  16. Chiral charge erasure via thermal fluctuations of magnetic helicity

    International Nuclear Information System (INIS)

    Long, Andrew J.; Sabancilar, Eray

    2016-01-01

    We consider a relativistic plasma of fermions coupled to an Abelian gauge field and carrying a chiral charge asymmetry, which might arise in the early Universe through baryogenesis. It is known that on large length scales, λ≳1/(αμ_5), the chiral anomaly opens an instability toward the erasure of chiral charge and growth of magnetic helicity. Here the chemical potential μ_5 parametrizes the chiral asymmetry and α is the fine-structure constant. We study the process of chiral charge erasure through the thermal fluctuations of magnetic helicity and contrast with the well-studied phenomenon of Chern-Simons number diffusion. Through the fluctuation-dissipation theorem we estimate the amplitude and time scale of helicity fluctuations on the length scale λ, finding δ H∼λT and τ∼αλ"3T"2 for a relativistic plasma at temperature T. We argue that the presence of a chiral asymmetry allows the helicity to grow diffusively for a time t∼T"3/(α"5μ_5"4) until it reaches an equilibrium value H∼μ_5T"2/α, and the chiral asymmetry is partially erased. If the chiral asymmetry is small, μ_5< T/α, this avenue for chiral charge erasure is found to be slower than the chiral magnetic effect for which t∼T/(α"3μ_5"2). This mechanism for chiral charge erasure can be important for the hypercharge sector of the Standard Model as well as extensions including U(1) gauge interactions, such as asymmetric dark matter models.

  17. Vibration of helical springs in cross water flow

    International Nuclear Information System (INIS)

    Axisa, F.; Brunet, G.

    1987-05-01

    The purpose of this paper is to present new experimental data on vortex-shedding induced vibration on helical springs subjected to cross-flows. Intense locked-in vibration were observed on the natural modes of axial displacement. A simplified model is tentatively proposed to interpret the experimental data which is based on an analogy with vortex-shedding as observed on straight tube rows

  18. Light scattering measurements supporting helical structures for chromatin in solution.

    Science.gov (United States)

    Campbell, A M; Cotter, R I; Pardon, J F

    1978-05-01

    Laser light scattering measurements have been made on a series of polynucleosomes containing from 50 to 150 nucleosomes. Radii of gyration have been determined as a function of polynucleosome length for different ionic strength solutions. The results suggest that at low ionic strength the chromatin adopts a loosely helical structure rather than a random coil. The helix becomes more regular on increasing the ionic strength, the dimension resembling those proposed by Finch and Klug for their solenoid model.

  19. Cylindrical Taylor states conserving total absolute magnetic helicity

    Science.gov (United States)

    Low, B. C.; Fang, F.

    2014-09-01

    The Taylor state of a three-dimensional (3D) magnetic field in an upright cylindrical domain V is derived from first principles as an extremum of the total magnetic energy subject to a conserved, total absolute helicity Habs. This new helicity [Low, Phys. Plasmas 18, 052901 (2011)] is distinct from the well known classical total helicity and relative total helicity in common use to describe wholly-contained and anchored fields, respectively. A given field B, tangential along the cylindrical side of V, may be represented as a unique linear superposition of two flux systems, an axially extended system along V and a strictly transverse system carrying information on field-circulation. This specialized Chandrasekhar-Kendall representation defines Habs and permits a neat formulation of the boundary-value problem (BVP) for the Taylor state as a constant-α force-free field, treating 3D wholly-contained and anchored fields on the same conceptual basis. In this formulation, the governing equation is a scalar integro-partial differential equation (PDE). A family of series solutions for an anchored field is presented as an illustration of this class of BVPs. Past treatments of the constant-α field in 3D cylindrical geometry are based on a scalar Helmholtz PDE as the governing equation, with issues of inconsistency in the published field solutions discussed over time in the journal literature. The constant-α force-free equation reduces to a scalar Helmholtz PDE only as special cases of the 3D integro-PDE derived here. In contrast, the constant-α force-free equation and the scalar Helmholtz PDE are absolutely equivalent in the spherical domain as discussed in Appendix. This theoretical study is motivated by the investigation of the Sun's corona but the results are also relevant to laboratory plasmas.

  20. Determining the helicity structure of third generation resonances

    International Nuclear Information System (INIS)

    Papaefstathiou, Andreas

    2011-11-01

    We examine methods that have been proposed for determining the helicity structure of decays of new resonances to third generation quarks and/or leptons. We present analytical and semi-analytical predictions and assess the applicability of the relevant variables in realistic reconstruction scenarios using Monte Carlo-generated events, including the effects of QCD radiation and multiple parton interactions, combinatoric ambiguities and fast detector simulation. (orig.)