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11.
A simple analytical model is proposed to describe the transversal spatial structure of a tridimensional rotationally symmetric pulsed beam. The spatial behaviour of the pulse amplitude is shown to be linked to its (measurable) second- and higher-order intensity moments, namely, beam width, quality parameter and kurtosis. As an illustrative experimental example, this model has been applied to high-quality TEA CO2 laser pulses. This revised version was published online in November 2006 with corrections to the Cover Date.  相似文献   
12.

Background  

The involvement of astrocyte water channel aquaporin-4 (AQP4) in autoimmune diseases of the central nervous system has been suggested following the identification of AQP4 autoantibodies in neuromyelitis optica, an inflammatory demyelinating disease.  相似文献   
13.
Let pn be the nth prime. Then this paper is concerned with provingthe following result on the distribution of consecutive primes. The exponent of x in this theorem improves on the work of Heath-Brownwho proved (1) with exponent . Under the Riemann hypothesisone can prove (1) with exponent .The proof of the theorem startswith the Heath-Brown–Linnik identity which leads to aformula giving the number of primes in an interval in termsof coefficients of certain Dirichlet series. I then estimatethe coefficients by using, among other things, the informationwhich can be gained from Montgomery's mean value theorem andHuxley's version of the Hal' asz lemma. Furthermore, by usingfamiliar sieve arguments I am able to discard some of the coefficientsallowing us to gain an improvement over the previous resultof Heath-Brown. 1991 Mathematics Subject Classification: 11N05.  相似文献   
14.
The time-dependent Schrödinger equation is solved numerically for the case of a Gaussian wave packet incident on a time-varying potential barrier. The time evolving reflection and transmission probabilities of the wave packet are computed for several different time-dependent boundary conditions obtained by reducing or increasing the height of the potential barrier. We show that in the case when the barrier height is reduced to zero, a time interval is found during which the reflection probability is larger (superarrivals) compared to the unperturbed case. We further show that the transmission probability exhibits superarrivals when the barrier is raised from zero to a finite value of its height. Superarrivals could be understood by ascribing the features of a real physical field to the Schrödinger wave function which acts as a carrier through which a disturbance, resulting from the boundary condition being perturbed, prpagates from the barrier to the detectors measuring reflected and transmitted probabilities. The speed of propagation of this effect depends upon the rate of reducing or raising the barrier height, thus suggesting an application for secure information transfer using superarrivals.  相似文献   
15.
Our studies describe the inflammatory response in rabbit skin induced by topical application of 8-methoxypsoralen (8-MOP) and UVA-visible irradiation (320-700 nm). Increase in vascular permeability (iVP) and accumulation of polymorphonuclear leucocytes (aPMN) at the test sites were quantitated using 125I-albumin and 51Cr-labelled PMNs respectively. Erythema was graded visually. 8-MOP cream was applied topically and irradiated. The erythemal response, aPMN and iVP at the test sites were quantitated at 6, 24, 48 and 72 h post-irradiation. The iVP and aPMN were maximal at 24 h; the erythemal response was the same at 24-48 h. The responses were dependent on 8-MOP concentration and irradiation dose. Topical application of 200 micrograms 8-MOP cream followed by irradiation for 2 h (9.4 J cm-2) produced 3-7 times iVP, 2-4 times aPMN and intense erythema at the test sites after 24 h. Neither aPMN nor iVP was detected before 6 h and erythemal response was not observable up to 16 h after irradiation. The aPMN and iVP gradually subsided in 72 h, although the erythemal response was still present. The repeated exposure of 8-MOP-treated sites for three consecutive days 24 h apart did not produce appreciable iVP or aPMN at 72 h or 24 h after the last exposure; however, erythema persisted. The 8-MOP-treated sites previously exposed for three consecutive days on reapplication of 8-MOP cream plus irradiation showed significantly less response compared with non-pretreated sites. Our results suggest that the erythemal response is not directly related to either iVP or aPMN.  相似文献   
16.
ZnTe with a high photosensitivity has been prepared by annealing single crystals of the material in an atmosphere of Zn and Ga metal and then quenching to room temperature. This material is p-type and exhibits a peak specific sensitivity of about 0.7.  相似文献   
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