Transient-thermal and isothermal studies of thermo-sensitive polymer solution with ultrasound resonator technology

High resolution and high sensitivity ultrasound resonator technology offers unique possibilities for the investigation of polymer precipitation. Exemplarily, the aggregation of poly(N-isopropylacrylamide) units in block copolymers with poly(styrene sulfonate) is investigated. Long term changes, over hours and days, of both the ultrasound velocity and the attenuation were detected during isothermal studies at temperatures in the vicinity (below as well as above) of the critical solution temperature. Apparent activation free energies of the precipitation and re-dissolution of the poly(N-isopropylacrylamide) block have been determined for the first time. The apparent activation energies are in the order of up to a few thousands kJ/mol, which can be explained by a high cooperativity of the precipitation process.     

Analytical characterization of palatinit (author's transl)]

The reaction product of the catalytic hydrogenation of isomaltulose (palatinose) is a mixture of alpha-D-glucopyranosido-1,6-sorbitol and alpha-D-glucopyranosido-1,6-mannitol designated palatinit. Because of its high potential as a sugar substitute methods for the identification and characterization of hydrogenation products and for the determination of palatinit as an ingredient in food preparations and biological samples are required. Several working procedures are described in full detail including thin layer and gas chromatography as well as enzymatic and chemical determinations.     

Global exponential stability for uncertain bidirectional associative memory neural networks with multiple time‐varying delays via LMI approach

The global exponential stability for uncertain delayed bidirectional associative memory neural networks (DBAMNN) with multiple time‐varying delays is considered in this paper. Delay‐dependent criteria are proposed to guarantee the robust stability of DBAMNN via linear matrix inequality approach. Two classes of system uncertainties are investigated in this paper. Some numerical examples are given to illustrate the effectiveness of our results. From the numerical simulations, significant improvement over the recent results can be observed. Copyright © 2007 John Wiley & Sons, Ltd.     

Concurrent search of mobile users in cellular networks

In this paper, we propose to concurrently search for a number of mobile users in a wireless cellular network based on the probabilistic information about the locations of mobile users. The concurrent search approach guarantees that all k mobile users will be located within k time slots. It is shown that even in the worst case when mobile users appear equally in all the cells of the network, the concurrent search approach is able to reduce the average paging cost by 25%. More importantly, this is achieved without an increase in the worst case paging delay or in the worst case paging cost. Depending on the total number of mobile users to be located, total number of cells in the network, and the probabilistic information about the locations of mobile users, the reduction of the average paging cost due to the usage of the concurrent search approach ranges from 25% to 88%. The case in which perfect probabilistic information is unavailable is also studied.     

A novel wavelength-division multiplexer using grating-assisted two-mode interference

A novel design of wavelength-division multiplexer based on two-mode interference assisted by a highly dispersive grating structure is two-dimensionally simulated and analyzed using finite-difference time-domain method. We show that the designed grating waveguide provides a mode-dependent reflection spectrum which can be used to modify the beat lengths of the two selected wavelengths 1342 and 1560 nm, so that they can be divided in a very short distance about 48 /spl mu/m. Simulation results show that contrasts /spl sim/12 dB and insertion losses about 2 dB could be achieved.     

Delayed onset of Alzheimer's disease with nonsteroidal anti-inflammatory and histamine H2 blocking drugs

Factors that modify onset of Alzheimer's disease (AD) may be revealed by comparing environmental exposures in affected and unaffected members of discordant twin pairs or sibships. Among siblings at high risk of AD, sustained use of nonsteroidal anti-inflammatory drugs (NSAIDs) was associated with delayed onset and reduced risk of AD. After adjustment for use of NSAIDs, there was minimal effect on onset with reported history of any of three common illnesses (arthritis, diabetes, or acid-peptic disease). However, independent of exposure to NSAIDs, onset was unexpectedly delayed in those reporting extended use of histamine H2 blocking drugs. Randomized clinical trials will be needed to affirm the utility of these drugs for prevention, but the present findings may have implications for pathogenesis: because NSAIDs block the calcium-dependent postsynaptic cascade that induces excitotoxic cell death in NMDA-reactive neurons, and because histamine potentiates such events, excitotoxicity may deserve additional investigation in AD.     

GSM数字移动通信系统的越区切换

切换技术是GSM数字移动通信系统保证移动中用户通信质量的一个重要手段。本文简要说明切换及其起因、启动标准和类型 ,并阐述基站决定切换启动的三个不同阶段的算法和要求 ,最后重点介绍网络系统中各种不同范围切换控制的信令关系及其实现过程。     

Noncoherent summation of multiple reduced-rank test statistics forfrequency-hopped STAP

A new noncoherent CFAR detection algorithm for STAP radar is developed, which noncoherently integrates a number of coherent, reduced-rank, CFAR tests developed by the authors in a previous paper. This new noncoherent detection criterion provides a significant improvement in detection performance with no need to increase the transmitter power