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61.
The effect of standing waves on the ear canal measurement of eardrum sound pressure level (SPL) was determined by both calculation and measurement. Transmission line calculations of the standing wave were made using the dimensions of the ANSI S3.25-1979 ear simulator and three different eardrum impedances. Standing wave curves have been obtained for the standard eardrum impedance at 1-kHz intervals in the range of 1-8 kHz. The changes in standing wave position due to each of the three eardrum impedances and their effects on ear canal measurements of SPL were computed for each of the eardrum impedances. Ear canal SPL measurements conducted on simulators modified to correspond to the eardrum impedances used in the calculations were compared to the computed values. Differences between eardrum SPLs and those measured at different locations in the ear canal approached a standing wave ratio (SWR) of 10-12 dB as the position of the measuring probe approached the standing wave minimum at each frequency. These maximum differences compared favorably with data developed by other investigators from real ears. Differences due to the eardrum impedance were found to be significant only in the frequency region of 2-5 kHz. Calibration of probes in a standard or modified ANSI simulator at the same distance from the eardrum as in the real ear reduces the eardrum SPL measurement errors to those resulting from differences in eardrum impedance. 相似文献
62.
Rvachev MM Benmokhtar F Penel-Nottaris E Aniol KA Bertozzi W Boeglin WU Butaru F Calarco JR Chai Z Chang CC Chen JP Chudakov E Cisbani E Cochran A Cornejo J Dieterich S Djawotho P Duran W Epstein MB Finn JM Fissum KG Frahi-Amroun A Frullani S Furget C Garibaldi F Gayou O Gilad S Gilman R Glashausser C Hansen JO Higinbotham DW Hotta A Hu B Iodice M Iomni R de Jager CW Jiang X Jones MK Kelly JJ Kox S Kuss M Laget JM De Leo R Lerose JJ Liatard E Lindgren R Liyanage N Lourie RW Malov S 《Physical review letters》2005,94(19):192302
We have studied the quasielastic 3He(e,e(')p)2H reaction in perpendicular coplanar kinematics, with the energy and the momentum transferred by the electron fixed at 840 MeV and 1502 MeV/c, respectively. The 3He(e,e(')p)2H cross section was measured for missing momenta up to 1000 MeV/c, while the A(TL) asymmetry was extracted for missing momenta up to 660 MeV/c. For missing momenta up to 150 MeV/c, the cross section is described by variational calculations using modern 3He wave functions. For missing momenta from 150 to 750 MeV/c, strong final-state interaction effects are observed. Near 1000 MeV/c, the experimental cross section is more than an order of magnitude larger than predicted by available theories. The A(TL) asymmetry displays characteristic features of broken factorization with a structure that is similar to that generated by available models. 相似文献
63.
The syntheses of the 7-phenylpyrimido[5,4-d][1]benzazepin-2-ones 3, 4 , and 5 are described. The 7-phenyl group was introduced by phenylation of the lactam nitrogen in 10, 13 and 16 respectively. One of these compounds, 5 , showed moderate activity as a CNS agent. 相似文献
64.
Nucleophilic displacement of aromatic fluorine. Part V. Use of nitrogen heterocycles as nucleophiles
Norman W. Gilman Betty C. Holland Gregory R. Walsh R. Ian Fryer 《Journal of heterocyclic chemistry》1977,14(7):1157-1162
The scope of the nucleophilic displacement of aromatic halogens on 1,4-benzodiazepine precursors by the anions of pyrroles, pyrazoles and imidazoles was studied both with and without electron-withdrawing substitutents on the heterocyclic nucleophiles. Some of the products proved to be useful intermediates for the synthesis of novel fused 1,4-benzodiazepines. 相似文献
65.
Wijesooriya K Afanasev A Amarian M Aniol K Becher S Benslama K Bimbot L Bosted P Brash E Calarco J Chai Z Chang CC Chang T Chen JP Choi S Chudakov E Churchwell S Crovelli D Dieterich S Dumalski S Dutta D Epstein M Fissum K Fox B Frullani S Gao H Gao J Garibaldi F Gayou O Gilman R Glamazdin S Glashausser C Gomez J Gorbenko V Hansen O Holt RJ Hovdebo J Huber GM de Jager CW Jiang X Jones C Jones MK Kelly J Kinney E Kooijman E Kumbartzki G Kuss M LeRose J Liang M Lindgren R Liyanage N Malov S 《Physical review letters》2001,86(14):2975-2979
We present measurements of the recoil proton polarization for the d(gamma-->,p-->)n reaction at straight theta(c.m.) = 90 degrees for photon energies up to 2.4 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. The induced polarization p(y) vanishes above 1 GeV, contrary to meson-baryon model expectations, in which resonances lead to large polarizations. However, the polarization transfer Cx does not vanish above 1 GeV, inconsistent with hadron helicity conservation. Thus, we show that the scaling behavior observed in the d(gamma,p)n cross sections is not a result of perturbative QCD. These data should provide important tests of new nonperturbative calculations in the intermediate energy regime. 相似文献
66.
Volmer J Abbott D Anklin H Armstrong C Arrington J Assamagan K Avery S Baker OK Blok HP Bochna C Brash EJ Breuer H Chant N Dunne J Eden T Ent R Gaskell D Gilman R Gustafsson K Hinton W Huber GM Jackson H Jones MK Keppel C Kim PH Kim W Klein A Koltenuk D Liang M Lolos GJ Lung A Mack DJ McKee D Meekins D Mitchell J Mkrtchyan H Mueller B Niculescu G Niculescu I Pitz D Potterveld D Qin LM Reinhold J Shin IK Stepanyan S Tadevosyan V Tang LG van der Meer RL Vansyoc K Van Westrum D Vulcan W Wood S 《Physical review letters》2001,86(9):1713-1716
Separated longitudinal and transverse structure functions for the reaction 1H(e,e(')pi(+))n were measured in the momentum transfer region Q2 = 0.6--1.6 (GeV/c)(2) at a value of the invariant mass W = 1.95 GeV. New values for the pion charge form factor were extracted from the longitudinal cross section by using a recently developed Regge model. The results indicate that the pion form factor in this region is larger than previously assumed and is consistent with a monopole parametrization fitted to very low Q2 elastic data. 相似文献
67.
Amarian M Auerbach L Averett T Berthot J Bertin P Bertozzi W Black T Brash E Brown D Burtin E Calarco J Cates G Chai Z Chen JP Choi S Chudakov E Cisbani E de Jager CW Deur A DiSalvo R Dieterich S Djawotho P Finn JM Fissum K Fonvieille H Frullani S Gao H Gao J Garibaldi F Gasparian A Gilad S Gilman R Glamazdin A Glashausser C Goldberg E Gomez J Gorbenko V Hansen JO Hersman B Holmes R Huber GM Hughes E Humensky B Incerti S Iodice M Jensen S Jiang X Jones C Jones G Jones M Jutier C Ketikyan A 《Physical review letters》2004,93(15):152301
The generalized forward spin polarizabilities gamma(0) and delta(LT) of the neutron have been extracted for the first time in a Q2 range from 0.1 to 0.9 GeV2. Since gamma(0) is sensitive to nucleon resonances and delta(LT) is insensitive to the Delta resonance, it is expected that the pair of forward spin polarizabilities should provide benchmark tests of the current understanding of the chiral dynamics of QCD. The new results on delta(LT) show significant disagreement with chiral perturbation theory calculations, while the data for gamma(0) at low Q2 are in good agreement with a next-to-leading-order relativistic baryon chiral perturbation theory calculation. The data show good agreement with the phenomenological MAID model. 相似文献
68.
Angle-resolved photoemission is used to determine the change in the electronic states of Ni induced by doping with Fe and Cr. Well-defined spin and k states are selected using high energy and k resolution combined with single crystal alloys. Iron suppresses the mean free path of minority spins only, while chromium suppresses both spins and decreases the magnetic splitting. The strong variation of these effects from one impurity to the other supports the concept of magnetic doping. 相似文献
69.
Schulte EC Ahmidouch A Armstrong CS Arrington J Asaturyan R Avery S Baker OK Beck DH Blok HP Bochna CW Boeglin W Bosted PY Bouwhuis M Breuer H Brown DS Bruell A Cadman RV Carlini R Chant NS Cochran A Cole L Danagoulian S Day DB Dunne JA Dutta D Ent R Fenker HC Fox B Gan L Gao H Garrow K Gaskell D Gasparian A Geesaman DF Gilman R Glashausser C Gueye P Harvey M Holt RJ Jackson HE Jiang X Keppel CE Kinney ER Liang Y Lorenzon W Lung AF Mack DJ Markowitz PE Martin J McIlhany K McKee D Meekins DG 《Physical review letters》2001,87(10):102302
The first measurements of the d(gamma,p)n differential cross section at forward angles and photon energies above 4 GeV were performed at the Thomas Jefferson National Accelerator Facility (JLab). The results indicate evidence of an angular dependent scaling threshold. Results at straight theta(cm) = 37 degrees are consistent with the constituent counting rules for E(gamma) greater, similar 4 GeV, while those at 70 degrees are consistent with the constituent counting rules for E(gamma) greater, similar 1.5 GeV. 相似文献
70.
Mauro Zammarano Jeffrey W. Gilman Marc Nyden Eli M. Pearce Menachem Lewin 《Macromolecular rapid communications》2006,27(9):693-696
Summary: Evidence of clay migration from the core to the surface of poly(propylene)/montmorillonite nanocomposites is provided. A three‐ to fivefold increase in the clay concentration of the surface is obtained during isothermal heating in oxidative atmosphere. The mechanism of migration is investigated by means of attenuated total reflectance Fourier transform infrared spectrometry. It is shown that oxygen plays a fundamental role in the migration mechanism.