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941.
研究了一种新型模拟双折射结构DWDM滤波器的中心频率和带宽的可调谐特性.研究表明:当给定满足一定平坦化要求的光谱透射率所需的各模拟波片中偏振旋转器的旋转角时,通过模拟波片中楔形介质对的相对位移来调节光在各模拟波片中的光程差,同时保持光程差仍满足特定的比例关系,可实现中心频率及带宽的调谐.当光在各模拟波片中的光程差变化较小时,可实现中心频率的调谐,此时带宽的改变很小,可忽略不计;随着光程差变化的不断增大,带宽的改变则不能忽略. 相似文献
942.
943.
Detrended fluctuation analysis (DFA) is a scaling method commonly used for detecting long-range correlations in non-stationary time series. The DFA method uses a trend based on polynomial fitting to extract and quantify fluctuations at different time scales. Basically, such procedure acts as a (non-dynamical) high-pass filter that removes time series components below a given time scale. As an alternative to the polynomial fitting approach, this paper proposes a DFA method based on well-known high-pass filters (e.g., Butterworth, elliptic, etc.). Numerical results show that the proposed DFA approach yields results similar to traditional DFA method. Maybe, the main advantage of the proposed DFA method is that efficient implementations of high-pass filters are available commercially. 相似文献
944.
Junhan Yuh Louis Perez Wolfgang M. Sigmund Juan C. Nino 《Physica E: Low-dimensional Systems and Nanostructures》2007,37(1-2):254
Electrospinning is a versatile process for drawing fibers of diverse materials including polymers, ceramics, and composites. We demonstrate here its application in the synthesis of complex ceramic oxide materials. The phase formation and morphology of BaTiO3 nanofibers synthesized via electrospinning is investigated as a function of heat treatment conditions. Fully crystallized BaTiO3 nanofibers with the perovskite structure are obtained after annealing at 750 °C and show an average grain size of about 30 nm. Tetragonal crystal structure of the fibers is indicated by XRD peak splitting (calculated c/a ratio=1.007), and confirmed by Raman spectroscopy. Furthermore, the advancement in heat treatment of the electrospun fibers yields single crystalline BaTiO3 nanofibers with 50 nm in diameter and lengths up to 1 μm. 相似文献
945.
Joshua D Shofner Juan G Vasquez Carole L Berger Richard L Edelson 《Journal of immune based therapies and vaccines》2007,5(1):2-11
Background
The malignant cells of cutaneous T cell lymphoma (CTCL) display immunogenic peptides derived from the clonal T cell receptor (TCR) providing an attractive model for refinement of anti-tumor immunization methodology. To produce a clinically meaningful anti-tumor response, induction of cytotoxic anti-CTCL cells must be maximized while suppressive T regulatory cells (Treg) should be minimized. We have demonstrated that engulfment of apoptotic CTCL cells by dendritic cells (DC) can lead to either CD8 anti-CTCL responses or immunosuppressive Treg induction. Treg generation is favored when the number of apoptotic cells available for ingestion is high. 相似文献946.
Dr. Sheng‐Liang Zhong Dr. Yang Lu Dr. Min‐Rui Gao Dr. Shu‐Juan Liu Jun Peng Le‐Cheng Zhang Prof. Dr. Shu‐Hong Yu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(17):5222-5231
A family of monodisperse YF3, YF3:Ce3+ and YF3:Ce3+/Ln3+ (Ln=Tb, Eu) mesocrystals with a morphology of a hollow spindle can be synthesized by a solvothermal process using yttrium nitrate and NH4F as precursors. The effects of reaction time, fluorine source, solvents, and reaction temperature on the synthesis of these mesocrystals have been studied in detail. The results demonstrate that the formation of a hollow spindle‐like YF3 can be ascribed to a nonclassical crystallization process by means of a particle‐based reaction route in ethanol. It has been shown that the fluorine sources selected have a remarkable effect on the morphologies and crystalline phases of the final products. Moreover, the luminescent properties of Ln3+‐doped and Ce3+/Ln3+‐co‐doped spindle‐like YF3 mesocrystals were also investigated. It turns out that Ce3+ is an efficient sensitizer for Ln3+ in the spindle‐like YF3 mesocrystals. Remarkable fluorescence enhancement was observed in Ce3+/Ln3+‐co‐doped YF3 mesocrystals. The mechanism of the energy transfer and electronic transition between Ce3+ and Ln3+ in the host material of YF3 mesocrystals was also explored. The cytotoxicity study revealed that these YF3‐based nanocrystals are biocompatible for applications, such as cellular imaging. 相似文献
947.
首先,利用Riesz变换和内插理论的结果得到了非齐次A-调和方程d^*A(x,g+du)=d^*h很弱解的一个先验估计.然后,利用这个先验估计得到了该方程很弱解的高阶可积性. 相似文献
948.
ZHANG Ya-Xing ZHANG Hai-Qiang LI Juan XU Tao ZHANG Chun-Yi TIAN Bo 《理论物理通讯》2008,49(4):833-838
In this paper, we put our focus on a variable-coe~cient fifth-order Korteweg-de Vries (fKdV) equation, which possesses a great number of excellent properties and is of current importance in physical and engineering fields. Certain constraints are worked out, which make sure the integrability of such an equation. Under those constraints, some integrable properties are derived, such as the Lax pair and Darboux transformation. Via the Darboux transformation, which is an exercisable way to generate solutions in a recursive manner, the one- and two-solitonic solutions are presented and the relevant physical applications of these solitonic structures in some fields are also pointed out. 相似文献
949.
950.
Juan Maldacena 《International Journal of Theoretical Physics》1999,38(4):1113-1133
We show that the large-N limits of certainconformal field theories in various dimensions includein their Hilbert space a sector describing supergravityon the product of anti-de Sitter spacetimes, spheres, and other compact manifolds. This is shown bytaking some branes in the full M/string theory and thentaking a low-energy limit where the field theory on thebrane decouples from the bulk. We observe that, in this limit, we can still trust thenear-horizon geometry for large N. The enhancedsupersymmetries of the near-horizon geometry correspondto the extra supersymmetry generators present in thesuperconformal group (as opposed to just the super-Poincaregroup). The 't Hooft limit of 3 + 1 N = 4 super-Yang–Mills at the conformal pointis shown to contain strings: they are IIB strings. Weconjecture that compactifications of M/string theory on various anti-de Sitterspacetimes is dual to various conformal field theories.This leads to a new proposal for a definition ofM-theory which could be extended to include fivenoncompact dimensions. 相似文献