Stable cationic capillary coating with successive multiple ionic polymer layers for capillary electrophoresis

A coated capillary modified with a cationic polymer was developed by using a novel coating procedure, successive multiple ionic-polymer (SMIL) coating. The SMIL coating was achieved by first attaching the cationic polymer to the capillary inner wall, and then the anionic polymer to the cationic polymer layer, and finally the cationic polymer to the anionic polymer layer. The stability of Polybrene (PB)-modified capillary made by SMIL coating was remarkably improved in comparison with a conventional PB-modified capillary. It endured during 600 replicate analyses and also showed strong stability against 1 M NaOH and 0.1 M HCl. The relative standard deviation of the run-to-run, day-to-day, and capillary-to-capillary coating was all below 1%, and good reproducibilities were obtained. The PB-modified capillary made by SMIL coating was applied to the basic protein analyses. It gave good performances for the protein analyses even when the pH of the electrolyte was near the isoelectric point (pI) of the protein. In addition, 0.1 M NaOH rinse prior to the sample injection allowed the reproducible analysis of a highly adsorptive sample such as plasma because the adsorbed sample could be flushed out of the capillary. Besides protein analyses, an efficient analysis of the cationic drugs by capillary electrophoresis/mass spectrometry (CE/MS) was also possible.     

Sequential Operations of Quantum Dot/Photonic Crystal All-Optical Switch With High Repetitive Frequency Pumping

A photonic crystal (PC)-based symmetric Mach-Zehnder type all-optical switch (PC-SMZ), previously operated by single pump pulse alone, has been operated newly by a multiple-pump pulse train corresponding to a repetition frequency of 40 GHz at pulse energy as low as 10 fJ. The device involves quantum dots (QDs) in two parallel PC arms as optical nonlinear media and functions as a time-differential phase modulator caused by the pump pulse inducing carriers in the QD. Prior to the switch operation, sequential time response of the phase shift for a probe pulse was investigated in detail by changing the power and repetition rate of the pump pulse in the straight PC waveguide configuration. Besides, PC and QD parameters were explored for possibility of 100% on-off switching ratio. As a result, five QD layers, 40-ps QD relaxation-time, 500-mum PC-length and use of as low as 0.05 c PC group-velocity (c; light velocity in vacuum) were found to implement the 100% switching ratio. Since each of these parameters has ever been achieved experimentally, the result will pave a promising way to an ultra-small and ultra-fast integrated all-optical switch.     

High‐resolution compressive channel estimation for broadband wireless communication systems

Broadband channel is often characterized by a sparse multipath channel where dominant multipath taps are widely separated in time, thereby resulting in a large delay spread. Accurate channel estimation can be done by sampling received signal with analog‐to‐digital converter (ADC) at Nyquist rate and then estimating all channel taps with high resolution. However, these Nyquist sampling‐based methods have two main disadvantages: (i) demand of the high‐speed ADC, which already exceeds the capability of current ADC, and (ii) low spectral efficiency. To solve these challenges, compressive channel estimation methods have been proposed. Unfortunately, those channel estimators are vulnerable to low resolution in low‐speed ADC sampling systems. In this paper, we propose a high‐resolution compressive channel estimation method, which is based on sampling by using multiple low‐speed ADCs. Unlike the traditional methods on compressive channel estimation, our proposed method can approximately achieve the performance of lower bound. At the same time, the proposed method can reduce communication cost and improve spectral efficiency. Numerical simulations confirm our proposed method by using low‐speed ADC sampling. Copyright © 2012 John Wiley & Sons, Ltd.     

Efficient multihop transmission scheme for error‐free relay forwarding in cooperative networks

Multihop cooperative communication is emerging as a key concept to extend the coverage area of the network and potentially increase the capacity. The spectral efficiency of such networks can be improved by adapting the transmission to time‐varying channel conditions, referred to as incremental relaying. Although such incremental relaying concepts are progressively being studied, many challenges, such as erroneous transmissions by intermediate nodes and end‐to‐end delay of the network, limit its practical use due to lack of an efficient implementation. This paper proposes an efficient multihop incremental relaying technique. In this method, erroneous relay forwarding is mitigated, and the overhead for coordination among nodes is reduced by exploiting the implicit feedback channel available due to the broadcast nature of wireless transmissions. The proposed scheme fully leverages the benefit of overhearing and eliminates the additional feedback slots required for validation. Further, it ensures reliable forwarding of information, which optimizes the throughput of multihop networks. Thorough analysis of the proposed scheme is performed under different deployment environments, and the theoretical analyses presented in this paper are supported with results from extensive simulation studies. Copyright © 2013 John Wiley & Sons, Ltd.     

Application of Rate Compatible Punctured Turbo Coded Hybrid ARQ to MC‐CDMA Mobile Radio

MC‐CDMA, a multicarrier (MC) modulation scheme based on code division multiple access (CDMA), is the most likely candidate for the next generation of mobile radio communications. The rate compatible punctured turbo (RCPT) coded hybrid automatic repeat request (HARQ) has been found to give improved throughput performance in a direct sequence (DS) CDMA system. However, the extent to which the RCPT HARQ improves the throughput performance of an MC‐CDMA system has not been fully understood. In this paper, we apply the RCPT HARQ to MC‐CDMA and evaluate by computer simulations its performance in a frequency selective Rayleigh fading channel. We found that the performance of RCPT HARQ MC‐CDMA is almost insensitive to channel characteristics. The performance can be drastically improved with receive diversity combined with space‐time transmit diversity. In addition, the comparison of RCPT HARQ MC‐CDMA, orthogonal frequency division multiplexing, and DS‐CDMA shows that under similar conditions the throughput of MC‐CDMA is the best in a frequency selective fading channel.     

Two types of lightning discharges to a high stack on the coast ofthe sea of Japan in winter

To clarify the characteristics of lightning on the coast of the Sea of Japan in the winter season, the current waveform and the progression of lightning discharge to a high stack were observed. Observation results from 1989 to 1994 show that: (1) there are two types of lightning discharges-one with large currents and strong luminosity in the lightning path, and the other with small currents of long duration and weak luminosity of lightning path; (2) the parameters of lightning currents of the two types of discharges are quite different; and (3) there is a quantitative correlation between the change of luminosity in a lightning path and the lightning current waveform     

Isolation of cDNA for a novel human protein KNP-I that is homologous to the E. coli SCRP-27A protein from the autoimmune polyglandular disease type I (APECED) region of chromosome 21q22.3

We have isolated cDNA clones for a novel human protein KNP-I from fetal brain and bone marrow cDNA libraries. Northern blot analysis indicated that the KNP-I gene is ubiquitously expressed in various human tissues. Significant homology of the KNP-I protein with Escherichia coli anti-sigma cross-reacting protein (SCRP-27A) (44% identity) and zebrafish (Brachydanio rerio) esl protein (49% identity) suggested that the KNP-I protein may be involved in a basic cellular function. Genomic sequencing revealed that the KNP-I gene consists of seven exons spanning 12 kb. Exon 5 was involved in alternative splicing. The KNP-I gene was mapped between D21S1460 and D21S25 on human chromosome 21q22.3, 26 kb distal to a Not 1 site of D21S1460. Thus, this novel KNP-I gene could be a candidate gene for autoimmune polyglandular disease type I (APECED) and other disorders mapped to this region.     

Suppression of lightning-induced overvoltages by distribution line surge arresters

The primary aim of surge arresters in power distribution lines is to protect lines and equipment from the voltage induced by nearby lightning strokes. To further improve power systems, methods to protect distribution lines against direct lightning strokes are still needed. An effective measure against direct lightning strokes is to increase the number of arresters. However, if the surge current is too large, some surge arresters absorb energy in excess of their capability and may break; this leads to a line fault. To evaluate the protective effect of the surge arresters against direct lightning strokes to overhead ground wire, the authors measured both the voltage across the surge arresters and the energy absorbed by them using a full-scale model line and a 12 MV impulse generator. The results were compared with simulation results by EMTP. There have been no previous studies making a comparison of this kind.     

External-internal linkages and overseas autonomy-control tension:the management dilemma of the Japanese R&D in Europe

By examining how external/internal linkages held by overseas R&D labs affect autonomy-control tension within multinational corporations (MNCs), managerial dilemmas pertinent to international R&D management are discussed, especially in the context of internationalization of Japanese R&D in Europe. R&D is liable to be affected by high autonomy-control tension due to countervailing institutional forces at the functional level (research/corporate) and the geographical level (host country/home country). The external linkages an overseas R&D lab develops tend to increase the expected degree of local autonomy vis-a-vis the parent. The external linkages tend to increase the need for internal control on the part of the parent, especially when such sensitive issues as intellectual property rights and research initiatives are involved. Managers use internal linkages as a condition based on which local autonomy can be granted. Similarly, a high degree of internal linkages tends to decrease the difficulty of internal control and would even allow for some potential increase in local autonomy. An alternative multinational linkage strategy becomes necessary for the Japanese MNCs in the era of global R&D management in which the conventional social/cultural control mechanism may break down. This paper attempts to provide a basic framework which enables the association of such differences in linkage patterns with autonomy-control tension in a systematic way so that some new insight would be obtained regarding this classic yet unresolved tension