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Now showing items 1 - 16 of 10373
Sun, M. D. Liu, Z. Huang, T. H. Zhang, W. Q. Andreyev, A. N. Ding, B. Wang, J. G. Liu, X. Y. Lu, H. Y. Hou, D. S. Gan, Z. G. Ma, L. Yang, H. B. Zhang, Z. Y. Yu, L. Jiang, J. Wang, K. L. Wang, Y. S. Liu, M. L. Li, Z. H. Li, J. Wang, X. Feng, A. H. Lin, C. J. Sun, L. J. Ma, N. R. Zuo, W. Xu, H. S. Zhou, X. H. Xiao, G. Q. Qi, C. Zhang, F. S.Fine structure in the alpha decay of U-223 was observed in the fusion-evaporation reaction Re-187(Ar-40, p3n) by using fast digital pulse processing technique. Two alpha-decay branches of U-223 feeding the ground state and 244 keV excited state of Th-219 were identified by establishing the decay chain U-223 (alpha(1)) under right arrow Th-219 (alpha(2)) under right arrow Ra-215 (alpha(3)) under right arrow Rn-211. The alpha-particle energy for the ground-state to ground-state transition of U-223 was determined to be 8993(17) keV, 213 keV higher than the previous value, the half-life was updated to be 62(-10)(+14) mu s. Evolution of nuclear structure for N =3D 131 even-Z isotones from Po to U was discussed in the frameworks of nuclear mass and reduced alpha-decay width, a weakening octupole deformation in the ground state of U-223 relative to its lighter isotones Ra-219 and Th-221 was suggested. (C) 2019 The Author(s). Published by Elsevier B.V.
Wang, L. Jiang, W. Y. Jiang, D. B. Zou, Y. F. Liu, Y. Y. Zhang, E. L. Hao, Q. Z. Zhang, D. G. Zhang, D. T. Peng, Z. Y. Xu, B. Yang, X. D. Lu, H. Y.Snowfall is an important component of Earth's climate system; however, long, continuous high-resolution records of global snowfall are lacking because of the absence of suitable proxies. In this study, diatom record from the sediments of Yunlong Lake, in the southeastern Tibetan Plateau, was used to reconstruct snowfall during the Younger Dryas (YD). Variations in the abundance of low-light-tolerant diatoms and diatom flux indicate that the duration of lake ice cover during the YD was significantly longer than that during the colder Heinrich event 1; this suggests that heavy snowfall, rather than temperatures, was responsible for the greater duration of lake ice cover during the YD. Thus, we conclude that prolonged, heavy snowfall occurred in the southeastern Tibetan Plateau during the YD. In addition, this conclusion is supported by the results of a climate model simulation that also suggest that heavy snowfall occurred at high latitude in the Northern Hemisphere during the YD. We propose that the heavy snowfall intensified cooling in Northern Hemisphere by increasing the albedo and that it increased hydrological variability at low latitudes by increasing the duration of the southward migration of the Intertropical Convergence Zone and by delaying the onset of the Asian summer monsoon. The snowfall would have been a source of continuous freshwater that acted as a positive feedback and resulted in a prolonged weakened state of the Atlantic meridional overturning circulation, which lasted for more than 1,000years. Overall, our results emphasize the amplification and positive feedback function of heavy snowfall in triggering abrupt climate change.
Wang, L. Jiang, W. Y. Jiang, D. B. Zou, Y. F. Liu, Y. Y. Zhang, E. L. Hao, Q. Z. Zhang, D. G. Zhang, D. T. Peng, Z. Y. Xu, B. Yang, X. D. Lu, H. Y.
Fu, H. S. Cao, J. B. Vaivads, A. Khotyaintsev, Y. V. Andre, M. Dunlop, M. Liu, W. L. Lu, H. Y. Huang, S. Y. Ma, Y. D. Eriksson, E.A magnetic reconnection event detected by Cluster is analyzed using three methods: Single-spacecraft Inference based on Flow-reversal Sequence (SIFS), Multispacecraft Inference based on Timing a Structure (MITS), and the First-Order Taylor Expansion (FOTE). Using the SIFS method, we find that the reconnection structure is an X line; while using the MITS and FOTE methods, we find it is a magnetic island (O line). We compare the efficiency and accuracy of these three methods and find that the most efficient and accurate approach to identify a reconnection event is FOTE. In both the guide and nonguide field reconnection regimes, the FOTE method is equally applicable. This study for the first time demonstrates the capability of FOTE in identifying magnetic reconnection events; it would be useful to the forthcoming Magnetospheric Multiscale (MMS) mission. ion
Fu, H. S. Cao, J. B. Cully, C. M. Khotyaintsev, Y. V. Vaivads, A. Angelopoulos, V. Zong, Q. -G. Santolik, O. Macusova, E. Andre, M. Liu, W. L. Lu, H. Y. Zhou, M. Huang, S. Y. Zhima, Z.During reconnection, a flux pileup region (FPR) is formed behind a dipolarization front in an outflow jet. Inside the FPR, the magnetic field magnitude and Bz component increase and the whistler-mode waves are observed frequently. As the FPR convects toward the Earth during substorms, it is obstructed by the dipolar geomagnetic field to form a near-Earth FPR. Unlike the structureless emissions inside the tail FPR, we find that the whistler-mode waves inside the near-Earth FPR can exhibit a discrete structure similar to chorus. Both upper band and lower band chorus are observed, with the upper band having a larger propagation angle (and smaller wave amplitude) than the lower band. Most chorus elements we observed are rising-tone type, but some are falling-tone type. We notice that the rising-tone chorus can evolve into falling-tone chorus within <3s. One of the factors that may explain why the waves are unstructured inside the tail FPR but become discrete inside the near-Earth FPR is the spatial inhomogeneity of magnetic field: we find that such inhomogeneity is small inside the near-Earth FPR but large inside the tail FPR.
Gong, Z. Hu, R. H. Lu, H. Y. Yu, J. Q. Wang, D. H. Fu, E. G. Chen, C. E. He, X. T. Yan, X. Q.An all-optical scheme is proposed for studying laser plasma based incoherent photon emission from inverse Compton scattering in the quantum electrodynamic regime. A theoretical model is presented to explain the coupling effects among radiation reaction trapping, the self-generated magnetic field and the spiral attractor in phase space, which guarantees the transfer of energy and angular momentum from electromagnetic fields to particles. Taking advantage of a prospective similar to 10(23) W cm(-2) laser facility, 3D particle-in-cell simulations show a gamma-ray flash with unprecedented multi-petawatt power and brightness of 1.7 x 10(23) photons s(-1) mm(-2) mrad(-2)/0.1% bandwidth (at 1 GeV). These results bode well for new research directions in particle physics and laboratory astrophysics exploring laser plasma interactions.
Liu, J. S. Wang, W. T. Lu, H. Y. Deng, A. H. Wang, C. Xia, C. Q. Li, W. T. Zhang, H. Nakajima, K. Li, R. X. Xu, Z. Z.We investigate the control of electron injection in the cascaded laser wakefield accelerators, optimization of seeding phase and the self-guided propagation of laser pulses between the two accelerators. The maximum acceleration gradient with energy spread narrowing was obtained when the seeding phase and the laser pulse propagation were optimized.
Fu, H. S. Cao, J. B. Mozer, F. S. Lu, H. Y. Yang, B.On 3 September 2009, the Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites observed a significant intensification of chorus in response to the interplanetary shock in the Earth's dayside plasma trough. We analyze the wave-particle interaction and reveal that the chorus intensification can be caused by the gyroresonance between the chorus and the energetic electrons. When the electrons are scattered from resonance points to low-density regions along the diffusion curves, a part of their energy can be lost and then transferred to amplify the chorus. During the compression of the magnetosphere, the temperature anisotropy of electrons is enhanced. This makes the electron diffusion and chorus intensification very effective. The maximum growth rate after the shock is about 50% greater than that before the shock. The lower-energy (15-25 keV) electrons contribute more to the growth of chorus due to the larger density gradient along the diffusion curve. The < 10 keV electrons are almost isotropic, so they contribute little to the amplification of chorus. We investigate the free energy for the chorus intensification and find that it can be generated through the local betatron acceleration and radial diffusion processes. The local betatron acceleration results from the shock-induced compression of the magnetosphere. The linear and nonlinear growth rates are also compared. We find that the linear diffusion process works well for the present case.
Zhao, Z. W. Lu, H. Y. Graham, L. Park, K. Gothe, R. W.The photoproduction of the Lambda*(1520) on both the proton and neutron have been studied by using the CLAS eg3 run data set. The reactions are gamma d -> K(+)Lambda*(n) and gamma d -> K(0)Lambda**(p) with Lambda* -> pK(-). Preliminary total and differential cross sections have been extracted in the photon energy region 1.75GeV < E(r) < 5.50GeV. This is the first time that the photoproduction of Lambda*(1520) on the neutron is reported, and we will extend the results on the proton to higher energies than in previous studies.
Liao, Q. Wu, M. J. Gong, Z. Geng, Y. X. Xu, X. H. Li, D. Y. Shou, Y. R. Zhu, J. G. Li, C. C. Yang, M. Li, T. S. Lu, H. Y. Ma, W. J. Zhao, Y. Y. Lin, C. Yan, X. Q.Proton acceleration during the interaction of an ultraintense (6 x 10(19) W/cm(2)) femtosecond (fs) laser pulse with a thin (2.5 mu m) foil target pre-ablated by a picosecond (ps) pulse is experimentally and numerically investigated. Enhancements in both proton cut-off energy and charge are observed with the target ablation due to a large number of energetic electrons generated from the preformed preplasma in front of the target. The enhanced proton beams are successfully collected at 4-9 MeV with +/- 4% energy spread and then transported to the irradiating platform. The results show that for the interaction between fs laser pulse and mu m-thickness target, proton energy and charge can be enhanced by target ablation using a ps laser pulse, which is valuable for application like cancer radiotherapy. Published by AIP Publishing.
Hen, O. Hakobyan, H. Shneor, R. Piasetzky, E. Weinstein, L. B. Brooks, W. K. Beck, S. May-Tal Gilad, S. Korover, I. Beck, A. Adhikari, K. P. Aghasyan, M. Amaryan, M. J. Pereira, S. Anefalos Arrington, J. R. Baghdasaryan, H. Ball, J. Battaglieri, M. Batourine, V. Bedlinskiy, I. Biselli, A. S. Bono, J. Boiarinov, S. Briscoe, W. J. Burkert, V. D. Carman, D. S. Celentano, A. Chandavar, S. Cole, P. L. Contalbrigo, M. Crede, V. D'Angelo, A. Dashyan, N. De Vita, R. De Sanctis, E. Deur, A. Djalali, C. Dodge, G. E. Doughty, D. Dupre, R. Egiyan, H. El Alaoui, A. El Fassi, L. Eugenio, P. Fedotov, G. Fegan, S. Fleming, J. A. Gabrielyan, M. Y. Gevorgyan, N. Gilfoyle, G. P. Giovanetti, K. L. Girod, F. X. Goetz, J. T. Gohn, W. Golovatch, E. Gothe, R. W. Griffioen, K. A. Guo, L. Hafidi, K. Harrison, N. Heddle, D. Hicks, K. Holtrop, M. Hyde, C. E. Ilieva, Y. Ireland, D. G. Ishkhanov, B. S. Isupov, E. L. Jo, H. S. Joo, K. Keller, D. Khandaker, M. Khetarpal, P. Kim, A. Klein, F. J. Koirala, S. Kubarovsky, A. Kubarovsky, V. Kuhn, S. E. Livingston, K. Lu, H. Y. MacGregor, I. J. D. Martinez, D. Mayer, M. McKinnon, B. Mineeva, T. Mokeev, V. Montgomery, R. A. Moutarde, H. Munevar, E. Camacho, C. Munoz Mustapha, B. Nadel-Turonski, P. Nasseripour, R. Niccolai, S. Niculescu, G. Niculescu, I. Osipenko, M. Ostrovidov, A. I. Pappalardo, L. L. Paremuzyan, R. Park, K. Park, S. Pasyuk, E. Phelps, E. Phillips, J. J. Pisano, S. Pivnyuk, N. Pogorelko, O. Pozdniakov, S. Price, J. W. Procureur, S. Protopopescu, D. Puckett, A. J. R. Raue, B. A. Rimal, D. Ripani, M. Ritchie, B. G. Rosner, G. Rossi, P. Sabatie, F. Saini, M. S. Schott, D. Schumacher, R. A. Seraydaryan, H. Sharabian, Y. G. Smith, G. D. Sober, D. I. Sokhan, D. Stepanyan, S. S. Stepanyan, S. Strauch, S. Taiuti, M. Tang, W. Taylor, C. E. Tian, Ye Tkachenko, S. Ungaro, M. Vernarsky, B. Vlassov, A. Voskanyan, H. Voutier, E. Walford, N. K. Watts, D. P. Wood, M. H. Zachariou, N. Zana, L. Zhang, J. Zheng, X. Zonta, I.Nuclear transparency, T-p(A), is a measure of the average probability for a struck proton to escape the nucleus without significant re-interaction. Previously, nuclear transparencies were extracted for quasi-elastic A(e, e' p) knockout of protons with momentum below the Fermi momentum, where the spectral functions are well known. In this Letter we extract a novel observable, the transparency ratio, T-p(A)/T-p(C-12), for knockout of high-missing-momentum protons from the breakup of short-range correlated pairs (2N-SRC) in Al, Fe and Pb nuclei relative to C. The ratios were measured at momentum transfer Q(2) >= 1.5 (GeV/c)(2) and x(B) >= 1.2 where the reaction is expected to be dominated by electron scattering from 2N-SRC. The transparency ratios of the knocked-out protons coming from 2N-SRC breakup are 20-30% lower than those of previous results for low missing momentum. They agree with Glauber calculations and agree with renormalization of the previously published transparencies as proposed by recent theoretical investigations. The new transparencies scale as A(-1/3), which is consistent with dominance of scattering from nucleons at the nuclear surface. (C) 2013 Elsevier B.V. All rights reserved.
Fu, H. S. Cao, J. B. Khotyaintsev, Yu. V. Sitnov, M. I. Runov, A. Fu, S. Y. Hamrin, M. Andre, M. Retino, A. Ma, Y. D. Lu, H. Y. Wei, X. H. Huang, S. Y.Dipolarization fronts (DFs) are frequently detected in the Earth's magnetotail from X-GSM=3D-30 R-E to X-GSM=3D-7 R-E. How these DFs are formed is still poorly understood. Three possible mechanisms have been suggested in previous simulations: (1) jet braking, (2) transient reconnection, and (3) spontaneous formation. Among these three mechanisms, the first has been verified by using spacecraft observation, while the second and third have not. In this study, we show Cluster observation of DFs inside reconnection diffusion region. This observation provides in situ evidence of the second mechanism: Transient reconnection can produce DFs. We suggest that the DFs detected in the near-Earth region (X-GSM>-10 R-E) are primarily attributed to jet braking, while the DFs detected in the mid- or far-tail region (X-GSM<-15 R-E) are primarily attributed to transient reconnection or spontaneous formation. In the jet-braking mechanism, the high-speed flow pushes the preexisting plasmas to produce the DF so that there is causality between high-speed flow and DF. In the transient-reconnection mechanism, there is no causality between high-speed flow and DF, because the frozen-in condition is violated.
Morrow, S. A. Guidal, M. Garcon, M. Laget, J. M. Smith, E. S. Adams, G. Adhikari, K. P. Aghasyan, M. Amaryan, M. J. Anghinolfi, M. Asryan, G. Audit, G. Avakian, H. Bagdasaryan, H. Baillie, N. Ball, J. P. Baltzell, N. A. Barrow, S. Battaglieri, M. Bedlinskiy, I. Bektasoglu, M. Bellis, M. Benmouna, N. Berman, B. L. Biselli, A. S. Blaszczyk, L. Bonner, B. E. Bookwalter, C. Bouchigny, S. Boiarinov, S. Bradford, R. Branford, D. Briscoe, W. J. Brooks, W. K. Bueltmann, S. Burkert, V. D. Butuceanu, C. Calarco, J. R. Careccia, S. L. Carman, D. S. Carnahan, B. Casey, L. Cazes, A. Chen, S. Cheng, L. Cole, P. L. Collins, P. Coltharp, P. Cords, D. Corvisiero, P. Crabb, D. Crannell, H. Crede, V. Cummings, J. P. Dale, D. Dashyan, N. De Masi, R. De Vita, R. De Sanctis, E. Degtyarenko, P. V. Denizli, H. Dennis, L. Deur, A. Dhamija, S. Dharmawardane, K. V. Dhuga, K. S. Dickson, R. Didelez, J. -P. Djalali, C. Dodge, G. E. Doughty, D. Dugger, M. Dytman, S. Dzyubak, O. P. Egiyan, H. Egiyan, K. S. El Fassi, L. Elouadrhiri, L. Eugenio, P. Fatemi, R. Fedotov, G. Fersch, R. Feuerbach, R. J. Forest, T. A. Fradi, A. Gavalian, G. Gevorgyan, N. Gilfoyle, G. P. Giovanetti, K. L. Girod, F. X. Goetz, J. T. Gohn, W. Gordon, C. I. O. Gothe, R. W. Graham, L. Griffioen, K. A. Guillo, M. Guler, N. Guo, L. Gyurjyan, V. Hadjidakis, C. Hafidi, K. Hakobyan, H. Hanretty, C. Hardie, J. Hassall, N. Heddle, D. Hersman, F. W. Hicks, K. Hleiqawi, I. Holtrop, M. Hourany, E. Hyde-Wright, C. E. Ilieva, Y. Ireland, D. G. Ishkhanov, B. S. Isupov, E. L. Ito, M. M. Jenkins, D. Jo, H. S. Johnstone, J. R. Joo, K. Juengst, H. G. Kalantarians, N. Keller, D. Kellie, J. D. Khandaker, M. Khetarpal, P. Kim, W. Klein, A. Klein, F. J. Klimenko, A. V. Kossov, M. Kramer, L. H. Kubarovsky, V. Kuhn, J. Kuhn, S. E. Kuleshov, S. V. Kuznetsov, V. Lachniet, J. Langheinrich, J. Lawrence, D. Li, Ji Livingston, K. Lu, H. Y. MacCormick, M. Marchand, C. Markov, N. Mattione, P. McAleer, S. McCracken, M. McKinnon, B. McNabb, J. W. C. Mecking, B. A. Mehrabyan, S. Melone, J. J. Mestayer, M. D. Meyer, C. A. Mibe, T. Mikhailov, K. Minehart, R. Mirazita, M. Miskimen, R. Mokeev, V. Morand, L. Moreno, B. Moriya, K. Moteabbed, M. Mueller, J. Munevar, E. Mutchler, G. S. Nadel-Turonski, P. Nasseripour, R. Niccolai, S. Niculescu, G. Niculescu, I. Niczyporuk, B. B. Niroula, M. R. Niyazov, R. A. Nozar, M. O'Rielly, G. V. Osipenko, M. Ostrovidov, A. I. Park, K. Park, S. Pasyuk, E. Paterson, C. Pereira, S. Anefalos Philips, S. A. Pierce, J. Pivnyuk, N. Pocanic, D. Pogorelko, O. Polli, E. Popa, I. Pozdniakov, S. Preedom, B. M. Price, J. W. Procureur, S. Prok, Y. Protopopescu, D. Qin, L. M. Raue, B. A. Riccardi, G. Ricco, G. Ripani, M. Ritchie, B. G. Rosner, G. Rossi, P. Rubin, P. D. Sabatie, F. Saini, M. S. Salamanca, J. Salgado, C. Santoro, J. P. Sapunenko, V. Schott, D. Schumacher, R. A. Serov, V. S. Sharabian, Y. G. Sharov, D. Shvedunov, N. V. Skabelin, A. V. Smith, L. C. Sober, D. I. Sokhan, D. Stavinsky, A. Stepanyan, S. S. Stepanyan, S. Stokes, B. E. Stoler, P. Strakovsky, I. I. Strauch, S. Taiuti, M. Tedeschi, D. J. Tkabladze, A. Tkachenko, S. Todor, L. Tur, C. Ungaro, M. Vineyard, M. F. Vlassov, A. V. Watts, D. P. Weinstein, L. B. Weygand, D. P. Williams, M. Wolin, E. Wood, M. H. Yegneswaran, A. Yurov, M. Zana, L. Zhang, J. Zhao, B. Zhao, Z. W.The ep -> e'pp(0) reaction has been measured using the 5.754 GeV electron beam of Jefferson Lab and the CLAS detector. This represents the largest ever set of data for this reaction in the valence region. Integrated and differential cross-sections are presented. The W, Q(2) and t dependences of the cross-section are compared to theoretical calculations based on the t-channel meson-exchange Regge theory, on the one hand, and on quark handbag diagrams related to Generalized Parton Distributions (GPDs) on the other hand. The Regge approach can describe at the approximate to 30% level most of the features of the present data while the two GPD calculations that are presented in this article which succesfully reproduce the high-energy data strongly underestimate the present data. The question is then raised whether this discrepancy originates from an incomplete or inexact way of modelling the GPDs or the associated hard scattering amplitude or whether the GPD formalism is simply inapplicable in this region due to higher-twists contributions, incalculable at present.
El Fassi, L. Zana, L. Hafidi, K. Holtrop, M. Mustapha, B. Brooks, W. K. Hakobyan, H. Zheng, X. Adhikari, K. P. Adikaram, D. Aghasyan, M. Amaryan, M. J. Anghinolfi, M. Arrington, J. Avakian, H. Baghdasaryan, H. Battaglieri, M. Batourine, V. Bedlinskiy, I. Biselli, A. S. Bookwalter, C. Branford, D. Briscoe, W. J. Bueltmann, S. Burkert, V. D. Carman, D. S. Celentano, A. Chandavar, S. Cole, P. L. Contalbrigo, M. Crede, V. D'Angelo, A. Daniel, A. Dashyan, N. De Vita, R. De Sanctis, E. Deur, A. Dey, B. Dickson, R. Djalali, C. Dodge, G. E. Doughty, D. Dupre, R. Egiyan, H. El Alaoui, A. Elouadrhiri, L. Eugenio, P. Fedotov, G. Fegan, S. Gabrielyan, M. Y. Garcon, M. Gevorgyan, N. Gilfoyle, G. P. Giovanetti, K. L. Girod, F. X. Goetz, J. T. Gohn, W. Golovatch, E. Gothe, R. W. Griffioen, K. A. Guidal, M. Guo, L. Hanretty, C. Heddle, D. Hicks, K. Holt, R. J. Hyde, C. E. Ilieva, Y. Ireland, D. G. Ishkhanov, B. S. Isupov, E. L. Jawalkar, S. S. Keller, D. Khandaker, M. Khetarpal, P. Kim, A. Kim, W. Klein, A. Klein, F. J. Kubarovsky, V. Kuhn, S. E. Kuleshov, S. V. Kuznetsov, V. Laget, J. M. Lu, H. Y. MacGregor, I. J. D. Mao, Y. Markov, N. Mayer, M. McAndrew, J. McKinnon, B. Meyer, C. A. Mineeva, T. Mirazita, M. Mokeev, V. Moreno, B. Moutarde, H. Munevar, E. Nadel-Turonski, P. Ni, A. Niccolai, S. Niculescu, G. Niculescu, I. Osipenkov, M. Ostrovidov, A. I. Pappalardo, L. L. Paremuzyan, R. Park, K. Park, S. Pasyuk, E. Pereira, S. Anefalos Phelps, E. Pozdniakov, S. Price, J. W. Procureur, S. Protopopescu, D. Raue, B. A. Reimer, P. E. Ricco, G. Rimal, D. Ripani, M. Ritchie, B. G. Rosner, G. Rossi, P. Sabatie, F. Saini, M. S. Salgado, C. Schott, D. Schumacher, R. A. Seraydaryan, H. Sharabian, Y. G. Smith, E. S. Smith, G. D. Sober, D. I. Sokhan, D. Stepanyan, S. S. Stepanyan, S. Stoler, P. Strauch, S. Taiuti, M. Tang, W. Taylor, C. E. Tedeschi, D. J. Tkachenko, S. Ungaro, M. Vernarsky, B. Vineyard, M. F. Voskanyan, H. Voutier, E. Watts, D. Weinstein, L. B. Weygand, D. P. Wood, M. H. Zachariou, N. Zhao, B. Zhao, Z. W.We have measured the nuclear transparency of the incoherent diffractive A(e,e' rho(0)) process in C-12 and Fe-56 targets relative to H-2 using a 5 GeV electron beam. The nuclear transparency, the ratio of the produced rho(0,)s on a nucleus relative to deuterium, which is sensitive to rho A interaction, was studied as function of the coherence length (l(c)), a lifetime of the hadronic fluctuation of the virtual photon, and the four-momentum transfer squared (Q(2)). While the transparency for both C-12 and Fe-56 showed no lc dependence, a significant Q(2) dependence was measured, which is consistent with calculations that included the color transparency effects. (C) 2012 Elsevier B.V. All rights reserved.
Xia, M. Jiang, J. Niu, X. H. Liu, J. Z. Wen, C. H. P. Lu, H. Y. Lou, X. Pu, Y. J. Huang, Z. C. Zhu, Xiyu Wen, H. H. Xie, B. P. Shen, D. W. Feng, D. L.LaO0.5F0.5BiSe2 is a new layered superconductor discovered recently, which shows the superconducting transition temperature of 3.5 K. With angle-resolved photoemission spectroscopy, we study the electronic structure of LaO0.5F0.5BiSe2 comprehensively. Two electron-like bands are located around the X point of the Brillouin zone, and the outer pockets connect with each other and form large Fermi surface around Gamma and M. These bands show negligible k(z) dispersion, indicating their two-dimensional nature. Based on the Luttinger theorem, the carrier concentration is about 0.53 e(-) per unit cell, close to its nominal value. Moreover, the photoemission data and the band structure calculations agree very well, and the renormalization factor is nearly 1.0, indicating the electron correlations in this material are rather weak. Our results suggest that LaO0.5F0.5BiSe2 is a conventional BCS superconductor without strong electron correlations.
Song, Y. X. Xin, R. L. Li, Z. C. Yu, H. W. Lun, W. H. Ye, J. Liu, A. Li, A. X. Li, J. W. Ye, J. Z. Hao, M. Q. Lu, H. Y. Sun, L. J.To optimise patients' outcomes and gain insight into transmitted drug resistance (TDR) among human immunodeficiency virus (HIV)-1 treatment-naive patients in Beijing, the prevalence of TDR was assessed. Demographic and clinical data of 1241 treatment-naive patients diagnosed between April 2014 and February 2015 were collected. TDR was defined using the Stanford University HIV drug resistance mutations database. The risk factors were evaluated by multi-logistic regression analysis. Among 932 successfully amplified cases, most were male (96.78%) and infected through men having sex with men (91.74%). Genotype were CRF01_AE (56.44%), B (20.60%), CRF07_BC (19.96%), C (1.61%) and other genotypes (1.39%). The overall prevalence of TDR was 6.12%. Most frequent mutations occurred in non-nucleoside reverse transcriptase inhibitors (NNRTIs) (3.11%), followed by protease inhibitors (PIs) (2.25%) and nucleoside reverse transcriptase inhibitors (NRTIs) (1.32%). Furthermore, HIV-1 genotype was associated with high risk of resistance, in which genotype C and other genotype may have higher risk for resistance. The prevalence among treatment-naive patients in Beijing was low. Resistance to NNRTIs was higher than with PIs or NRTIs. Continuous monitoring of regional levels of HIV-1 TDRs would contribute to improve treatment outcomes and prevent failures.