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51.
Kimberly K. J. Kinateder Patrick McDonald 《Proceedings of the American Mathematical Society》1999,127(9):2767-2772
Let be a smoothly bounded domain in Euclidean space and let be a diffusion in Euclidean space. For a class of diffusions, we develop variational principles which characterize the average of the moments of the exit time from of a particle driven by where the average is taken over all starting points in
52.
Matrix reactions of Mg, Zn and Cd atoms and NO2 have been performed. Infrared absorptions in the 1220 cm?1 range show isotopic shifts appropriate for M+NO2? species. Bands near 950 cm?1 in the zinc experiments are attributed to a different ion-pair structural isomer. 相似文献
53.
Dewald EL Suter LJ Landen OL Holder JP Schein J Lee FD Campbell KM Weber FA Pellinen DG Schneider MB Celeste JR McDonald JW Foster JM Niemann C Mackinnon AJ Glenzer SH Young BK Haynam CA Shaw MJ Turner RE Froula D Kauffman RL Thomas BR Atherton LJ Bonanno RE Dixit SN Eder DC Holtmeier G Kalantar DH Koniges AE Macgowan BJ Manes KR Munro DH Murray JR Parham TG Piston K Van Wonterghem BM Wallace RJ Wegner PJ Whitman PK Hammel BA Moses EI 《Physical review letters》2005,95(21):215004
The first hohlraum experiments on the National Ignition Facility (NIF) using the initial four laser beams tested radiation temperature limits imposed by plasma filling. For a variety of hohlraum sizes and pulse lengths, the measured x-ray flux shows signatures of filling that coincide with hard x-ray emission from plasma streaming out of the hohlraum. These observations agree with hydrodynamic simulations and with an analytical model that includes hydrodynamic and coronal radiative losses. The modeling predicts radiation temperature limits with full NIF (1.8 MJ), greater, and of longer duration than required for ignition hohlraums. 相似文献
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The presence of an alkenyl substituent on the terminal epoxide of a polyepoxide substrate enhances the yield of all-endo-regioselective tandem oxacyclization to trans-syn-trans-fused polycyclic ethers. For a substrate in which the epoxide and alkene functional groups are separated by two methylene substituents, a novel bromonium ion-induced endo-regioselective cyclization to bromooxepane is also described. [reaction: see text] 相似文献
56.
Stereoselective synthesis of d-desosamine diacetate ester (iii, R = Ac) was achieved from the glycal (ii). generated by tungsten carbonyl-catalyzed cycloisomerization of the corresponding amino-alkynol (i). A wide variety of N-substituents (R, R') are compatible with the cycloisomerization, provided that at least one R or R' is an acyl derivative. 相似文献
57.
A general dark-soliton solution of the Helmholtz equation (with defocusing Kerr nonlinearity) that has on- and off-axis, gray and black, paraxial and Helmholtz solitons as particular solutions, is reported. Modifications to soliton transverse velocity, width, phase period, and existence conditions are derived and explained in geometrical terms. Simulations verify analytical predictions and also demonstrate spontaneous formation of Helmholtz solitons and transparency of their interactions. 相似文献
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Prakhov S Tippens WB Allgower C Bekrenev V Berger E Briscoe WJ Clajus M Comfort JR Craig K Grosnick D Huber GM Isenhower D Knecht N Koetke D Koulbardis A Kozlenko N Kruglov S Kycia T Lolos GJ Lopatin I Manley DM Marusic A Manweiler R McDonald S Nefkens BM Olmsted J 《Physical review letters》2000,84(21):4802-4805
We report the first determination of the upper limit for the branching ratio of the CP forbidden decay eta-->4pi(0). No events were observed in a sample of 3.0x10(7) eta decays. The experiment was performed with the Crystal Ball multiphoton spectrometer installed in a separated pi(-) beam at the AGS (Alternating Gradient Synchrotron). At the 90% confidence limit, B(eta-->4pi(0))=6. 9x10(-7). 相似文献