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181.

The aim of this paper is twofold. First, we initiate a detailed study of the so-called Xs θ spaces attached to a partial differential operator. This include localization, duality, microlocal representation, subelliptic estimates, solvability and Lp (Lq ) estimates. Secondly, we obtain some theorems on the unique continuation of solutions to semilinear second order hyperbolic equations across strongly pseudo-convex surfaces. These results are proved using some new Lp Lq Carleman estimates, derived using the Xs θ spaces. Our theorems cover the subcritical case; in the critical case, the problem remains open. Similar results hold for higher order partial differential operators, provided that characteristic set satisfies a curvature conditions.  相似文献   
182.
A novel synthetic stratetegy for compounds labeled with the positron-emitting isotope carbon-11 is described. The use of precursors attached to a solid support via safety-catch linkers allows selective release of radiolabeled material, leaving unreacted precursor attached to the support. Two different linkers demonstrate the application to the preparation of radiolabeled N-alkyl tertiary amines and N-alkylsulfonamides. This technique is expected to lead to more widespread use of positron emission tomography for the in vivo analysis of compound behavior.  相似文献   
183.
We describe the first direct observations of turbulence in superfluid 3He-B. The turbulence is generated by a vibrating-wire resonator driven at velocities exceeding the pair-breaking critical velocity. It is detected by the resulting decrease in the thermal damping on a neighboring "detector" vibrating-wire resonator. The superfluid flow field associated with the turbulence Andreev reflects thermal quasiparticle excitations, effectively screening the detector wire, resulting in a decrease in the thermal damping.  相似文献   
184.
J.M. Hale 《Ultrasonics》1988,26(6):356-357
A method has been devised for determining the density of a fluid by measuring the velocity and amplitude of an ultrasonic pulse passed through it. The theory of the method is presented, together with the results of an experimental verification.  相似文献   
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Finite geometries in which each plane is projective or dual affine over the field of two elements, or affine over the field of three elements, are studied. It is shown that no connected geometry can mix all three species of planes, and the geometries in which projective and dual affine planes occur are classified.  相似文献   
188.
Methods to minimize the transfer of silicone from PDMS stamps during micro-contact printing have been investigated. This study focused on amino-silanes stamped onto PTFE substrates. Analysis of the stamped surfaces was through surface sensitive techniques such as XPS and time-of-flight secondary ion mass spectroscopy (TOF-SIMS). It was found that curing the PDMS at elevated temperatures minimized the amount of silicone transferred. The amount of silicone transferred also depended on the pretreatment of the stamp and the type of ink used.  相似文献   
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Using experiments involving cyclic voltammetry and stationary potential measurements, it was shown that siloxane polymers with covalently attached ferrocene and 1,1'-dimethylferrocene relays efficiently mediate electron transfer from reduced glycolate oxidase to a conventional carbon-paste electrode. Sensors containing these polymeric relay systems and glycolate oxidase respond rapidly to low (< 0.1 mM) glycolate concentrations, with steady-state current responses achieved in less than 1 min. The dependence of the sensor response on the nature of the siloxane polymer backbone, the type of polymer-bound redox mediator used and the amount of redox mediator present is discussed. From these considerations, sensors have been designed which can operate efficiently at low applied potential and can avoid decreased current response due to dissolved oxygen.  相似文献   
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