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91.
Holland CW Nielsen PL Dettmer J Dosso S 《The Journal of the Acoustical Society of America》2012,131(2):1066-1078
Seabed geoacoustic variability is driven by geological processes that occur over a wide spectrum of space-time scales. While the acoustics community has some understanding of horizontal fine-scale geoacoustic variability, less than O(10(0)) m, and large-scale variability, greater than O(10(3)) m, there is a paucity of data resolving the geoacoustic meso-scale O(10(0)-10(3)) m. Measurements of the meso-scale along an ostensibly "benign" portion of the outer shelf reveal three classes of variability. The first class was expected and is due to horizontal variability of layer thicknesses: this was the only class that could be directly tied to seismic reflection data. The second class is due to rapid changes in layer properties and/or boundaries, occurring over scales of meters to hundreds of meters. The third class was observed as rapid variations of the angle/frequency dependent reflection coefficient within a single observation and is suggestive of variability at scales of meter or less. Though generally assumed to be negligible in acoustic modeling, the second and third classes are indicative of strong horizontal geoacoustic variability within a given layer. The observations give early insight into possible effects of horizontal geoacoustic variability on long-range acoustic propagation and reverberation. 相似文献
92.
John Garnett Stan Yoshinobu 《Proceedings of the American Mathematical Society》2001,129(12):3543-3548
We prove that certain Cantor sets with non-sigma-finite one- dimensional Hausdorff measure have zero analytic capacity.
93.
I. N. Stan’kov A. A. Sergeeva I. D. Derevyagina 《Journal of Analytical Chemistry》2000,55(10):988-990
A method is proposed for the determination ofO-isobutylS-2-(N,N-diethylamino)ethyl methylphosphonate (mixed ester, ME) in spent decontaminating solutions by gas chromatography at a level
of 1 x 10-5%. The interfering effect of mono- and diisobutyl methylphosphonates (matrix components formed on the destruction of ME) is
eliminated by extraction and back extraction. The effect of bis(N,N-diethylaminoethyl) disulfide in the determination of ME is eliminated by changing the order of elution from a Chromatographic
column. Decontaminating solutions that are used in the laboratory practice for the detoxication of hydrophilic process ME
solutions are aqueous solutions of alkali hydroxide with additions of hydrogen peroxide and an emulsifier. 相似文献
94.
Chung‐Der Chen Andrew P. J. Brunskill Stan S. Hall Roger A. Lalancette Hugh W. Thompson 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(9):1148-1151
α‐Oxobenzeneacetic (phenylglyoxylic) acid, C8H6O3, adopts a transoid dicarbonyl conformation in the solid state, with the carboxyl group rotated 44.4 (1)° from the nearly planar benzoyl moiety. The heterochiral acid‐to‐ketone catemers [O?O = 2.686 (3) and H?O = 1.78 (4) Å] have a second, longer, intermolecular O—H?O contact to a carboxyl sp3 O atom [O?O = 3.274 (2) and H?O = 2.72 (4) Å], with each flat ribbon‐like chain lying in the bc plane and extending in the c direction. In α‐oxo‐2,4,6‐trimethylbenzeneacetic (mesitylglyoxylic) acid, C11H12O3, the ketone is rotated 49.1 (7)° from planarity with the aryl ring and the carboxyl group is rotated a further 31.2 (7)° from the ketone plane. The solid consists of chiral conformers of a single handedness, aggregating in hydrogen‐bonding chains whose units are related by a 31 screw axis, producing hydrogen‐bonding helices that extend in the c direction. The hydrogen bonding is of the acid‐to‐acid type [O?O = 2.709 (6) and H?O = 1.87 (5) Å] and does not formally involve the ketone; however, the ketone O atom in the acceptor molecule has a close polar contact with the same donor carboxyl group [O?O = 3.005 (6) and H?O = 2.50 (5) Å]. This secondary hydrogen bond is probably a major factor in stabilizing the observed cisoid dicarbonyl conformation. Several intermolecular C—H?O close contacts were found for the latter compound. 相似文献
95.
Stan Alama Lia Bronsard J. Alberto Montero 《Archive for Rational Mechanics and Analysis》2008,187(3):481-522
We construct local minimizers of the Gross–Pitaevskii energy, introduced to model Bose–Einstein condensates (BEC) in the Thomas–Fermi
regime which are subject to a uniform rotation. Our sample domain is taken to be a solid torus of revolution in with starshaped cross-section. We show that for angular speeds ωε = O(|ln ε|) there exist local minimizers of the energy which exhibit vortices, for small enough values of the parameter ε. These vortices concentrate at one or several planar arcs (represented by integer multiplicity rectifiable currents) which
minimize a line energy, obtained as a Γ-limit of the Gross–Pitaevskii functional. The location of these limiting vortex lines
can be described under certain geometrical hypotheses on the cross-sections of the torus. 相似文献
96.
Daniela-Mdlina Ciuc Anghel Anne-Marie Ciobanu Claudia Maria Guu Miriana Stan Gheorghe Tudor Daniela Luiza Baconi 《Molecules (Basel, Switzerland)》2022,27(23)
(1) Background: Methadone, along with buprenorphine, is the most commonly used drug for the treatment of opioid dependence. This study aimed to analyze methadone and its major metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenyl pyrrolidine (EDDP), in the urine and plasma of opiate addicts. The study group consisted of drug users voluntarily admitted to the detoxification center C.E.T.T.T. “St. Stelian” of Bucharest. Secondly, the study aimed to identify whether urine or plasma provides better results for the proposed method. (2) Methods: A GC-MS method, using an internal standard (diphenylamine) in the FULL-SCAN and SIM modes of operation and using the m/z = 72 ion for methadone and the m/z = 277 ion for EDDP, combined with a liquid–liquid extraction procedure was performed. (3) Results: The applied procedure allows the detection and quantification of methadone in both urine and plasma samples. EDDP was identified in patients with higher levels of methadone. Higher levels of methadone were detected in urine than in plasma samples. (4) Conclusions: This procedure can be used in clinical laboratories for the rapid determination of methadone levels in urine rather than in plasma. The procedure can be applied for the monitoring of methadone substitution treatment. 相似文献
97.
E. Rothenbach R. Laster P. Kolbach R. Buse O. Heinisch D. Satava W. Piratzky H. Krwawnik A. Heiduschka Elisabeth Bischoff W. Windisch M. Hamburg G. Bode H. Fink E. Berwald V. I. Staněk P. Pavlas Â. Boas A. Herzfeld F. M. Wieninger E. Helm 《Analytical and bioanalytical chemistry》1935,101(11-12):443-448
98.
99.
100.
Irena Rach?nková Svatoslav Staněk 《Journal of Mathematical Analysis and Applications》2004,291(2):741-756
The odd-order differential equation (−1)nx(2n+1)=f(t,x,…,x(2n)) together with the Lidstone boundary conditions x(2j)(0)=x(2j)(T)=0, 0?j?n−1, and the next condition x(2n)(0)=0 is discussed. Here f satisfying the local Carathéodory conditions can have singularities at the value zero of all its phase variables. Existence result for the above problem is proved by the general existence principle for singular boundary value problems. 相似文献