bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of poly[N‐isopropylacrylamide‐g‐poly(ethylene glycol)] with a reactive group at the poly(ethylene glycol) end and its thermosensitive self‐assembling character
Authors: Iijima Michihiro , Nagasaki Yukio 
Published: January 2006

AbstractPoly[N‐isopropylacrylamide‐g‐poly(ethylene glycol)]s with a reactive group at the poly(ethylene glycol) (PEG) end were synthesized by the radical copolymerization of N‐isopropylacrylamide with a PEG macromonomer having an acetal group at one end and a methacryloyl group at the other chain end. The temperature dependence of the aqueous solutions of the obtained graft copolymers was estimated by light scattering measurements. The intensity of the light scattering from aqueous polymer solutions increased with increasing temperature. In particular, at temperatures above 40°C, the intensity abruptly increased, indicating a phase separation of the graft copolymer due to the lower critical solution temperature (LCST) of the poly(N‐isopropylacrylamide) segment. No turbidity was observed even above the LCST, and this suggested a nanoscale self‐assembling structure of the graft copolymer. The dynamic light scattering measurements confirmed that the size of the aggregate was in the range of several tens of nanometers. The acetal group at the end of the PEG graft chain was easily converted to the aldehyde group by an acid treatment, which was analyzed by 1H NMR. Such a temperature‐induced nanosphere possessing reactive PEG tethered chains on the surface is promising for new nanobased biomedical materials. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1457–1469, 2006
Transition from crazing to shear deformation in ABS/PVC blends
Authors: Zhou C. , Bao X. Y. , Tan Z. Y. , Sun S. L. , Ao Y. H. , Yang H. D. , Zhang H. X. 
Published: January 2006

AbstractABS/PVC blends were prepared over a range of compositions by mixing PVC, SAN, and PB‐g‐SAN. All samples were designed to have a constant rubber level of 12 wt % and the ratio of total‐SAN to PVC in the matrix of the blends varied from 70.5/17.5 to 18/80. Transmission electron microscope and scanning electron microscope have been used to study deformation mechanisms in the ABS/PVC blends. Several different types of microscopic deformation mechanisms, depending on the composition of blends, were observed for the ABS/PVC blends. When the blend is a SAN‐rich system, the main deformation mechanisms were crazing of the matrix. When the blend is a PVC‐rich system, crazing could no longer be detected, while shear yielding of the matrix and cavitation of the rubber particles were the main mechanisms of deformation. When the composition of blend is in the intermediate state, both crazing and shear yielding of matrix were observed. This suggests that there is a transition of deformation mechanism in ABS/PVC blends with the change in composition, which is from crazing to shear deformation. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 687–695, 2006
Use of hydrogen/deuterium exchange mass spectrometry and mutagenesis as a tool to identify the binding region of inhibitors targeting the human mitotic kinesin Eg5
Authors: Brier Sébastien , Lemaire David , DeBonis Salvatore , Kozielski Frank , Forest Eric 
Published: January 2006

AbstractAn experimental procedure associating both hydrogen/deuterium exchange mass spectrometry (H/D‐MS) and mutagenesis was developed to identify the protein‐binding region of small inhibitors targeting the motor domain of the human mitotic kinesin Eg5. All the tested inhibitors decrease the deuterium incorporation rate of the same peptides corresponding to the following secondary structure elements: loop L5/helix α2 (region Tyr125‐Glu145) and strand β5/helix α3 (region Ile202‐Leu227). Replacement of these two regions by the equivalent ones from N. crassa conventional kinesin heavy chain completely abolishes the modification of the deuterium incorporation rate by the inhibitors as well as their effects on the basal ATPase activity. The six tested inhibitors thus share a common binding site on Eg5. The strategy reported here allows the regions of a protein involved in ligand binding to be rapidly pinpointed and can be applied to other proteins and used as a general in vitro screening procedure to identify compounds targeting specific binding regions. Copyright © 2006 John Wiley & Sons, Ltd.
2D‐DIGE analysis revealed reduced cytokeratin signaling in placenta with preeclampsia
Authors: Hass Ralf , Kirchner Markus , Hollwitz Bettina , Scharf Alexander 
Published: January 2006

AbstractPreeclampsia represents a severe pregnancy disorder associated with premature delivery and fetal growth retardation which also involves certain imbalances of the placental maturation and the placental integration into the surrounding tissues. To characterize possible differences in the development of normal and preeclamptic placentae, two‐dimensional SDS‐PAGE of 10 normal placental protein homogenates was performed and compared to the protein pattern of homogenates from 10 preeclamptic placentae. Thus, acidic proteins particularly of about 56 kDa were identified in normal placentae which were nearly undetectable in protein homogenates of preeclamptic placentae. Peptide mass finger printing by MALDI identified cytokeratins, especially cytokeratin‐10 as one of the differentially expressed protein. Quantitative data were obtained by two‐dimensional difference‐gel electrophoresis (2D DIGE). Labeling of normal and preeclamptic placental proteins with the fluorophors Cy5 and Cy3, respectively, and subsequent separation of these mixed samples by 2D DIGE revealed a differentially expressed protein spot at a 12.8‐fold higher fluorescence intensity in normal placentae as compared to preeclamptic placentae. MALDI analysis of this differentially expressed protein spot identified cytokeratin. In order to verify these results in individual placenta probes, cytokeratin‐10 Western blots were performed in 3 normal and preeclamptic placental homogenates of different gestational ages, respectively. Whereas a marked 56 kDa cytokeratin‐10 expression appeared in all normal placentae, there was only little if any detectable cytokeratin‐10 present in the preeclamptic placentae, respectively. These findings suggest that preeclampsia is accompanied by a significantly reduced cytokeratin signaling provided by 2D‐DIGE‐coupled MALDI analysis which represents a suitable technique to identify e. g. disease‐related alterations in protein patterns.
Interference management using basestation coordination in broadband wireless access networks
Authors: Ahmed Mohamed H. , Yanikomeroglu Halim , Mahmoud Samy 
Published: January 2006

AbstractThis paper proposes a transmission‐scheduling algorithm for interference management in broadband wireless access networks. The algorithm aims to minimize the cochannel interference using basestation coordination while still maintaining the other quality of service (QoS) requirements such as packet delay, throughput and packet loss. The interference reduction is achieved by avoiding (or minimizing) concurrent transmission of potential dominant interferers. Dynamic slot allocation based on traffic information in other cells/sectors is employed. In order to implement the algorithm in a distributed manner, basestations (BSs) have to exchange traffic information. Both real‐time and non‐real‐time services are considered in this work. Results show that significant reduction in the packet error rate can be achieved without increasing the packet delay at low to medium loading values and with a higher but acceptable packet delay at high loading values. Since ARQ schemes can also be used for packet error rate reduction, we compare the performance of the proposed scheme with that of ARQ. Results indicate that although ARQ is more effective in reducing packet error rate, the proposed algorithm incurs much less packet delay particularly at medium to high loading. Copyright © 2006 John Wiley & Sons, Ltd.
Some experimental and modeling results of widely varying urban environments on train mobile radio communication
Authors: Prasad M. V. S. N. , Singh Rajendra , Sarkar S. K. , Sarma A. D. 
Published: January 2006

AbstractA comparative study of urban mobile radio wave propagation characteristics in the UHF band has been carried out based on the field strength measurements conducted inside a moving train in two widely varying urban environments. Various prediction techniques are employed to compare the observed path losses with those of predicted ones in both the environments. The major fall out of the present study is the modification of Xia's model, which gave better agreement with the observed results. The deviations of the prediction techniques and their suitability have been discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Spectral properties of signal fading and Doppler spectra distribution in urban mobile communication links
Authors: Blaunstein N. , Ben‐Shimol Y. 
Published: January 2006

AbstractIn this work, we continue the analysis of a probabilistic approach and the corresponding stochastic multi‐parametric model of wave propagation, in built‐up areas with randomly distributed buildings. We have concentrated on the spectral properties of signal strength spatial variations and on Doppler spread spectrum distribution of signal power. The analysis is based on a unified stochastic approach of radio wave propagation above the built‐up terrain with applications to mobile communications. We analyze the signal power spectrum of spatial frequencies and the signal power distribution in the Doppler domain for moving vehicles, taking into account a Doppler shift proportional to the vehicle antenna speed relative to the base station. The comparison between the theoretical prediction and experimental data was motivated by the proposed stochastic model and other existing statistical models to verify the signal power distribution in the Doppler domain for various urban environments and terminal heights with respect to building rooftops. New effects of terrain features on signal spectrum are obtained, examined and compared with existing models. Copyright © 2006 John Wiley & Sons, Ltd.
On‐demand flow regulated routing for ad hoc wireless networks
Authors: Jian Ming‐Shen , Wu Peng‐Long , Lee Chung‐Nan 
Published: January 2006

AbstractIn this paper, we present an on‐demand flow regulated routing algorithm (OFRA) for ad hoc wireless networks. The OFRA consists of two parts: an intermediate node load evaluation process and a routing path selection process. The intermediate node load evaluation process evaluates the load efficiency of the intermediate nodes according to bandwidth, data packets and computing capability. The routing path selection process selects the routing path with lower flow and fewer intermediate nodes. The OFRA can prevent intermediate nodes to be overcrowded and distribute traffic load over routing paths more evenly. The simulation result shows that the percentage of blocked routing paths is reduced and the total flow is more balanced and distributed. Copyright © 2006 John Wiley & Sons, Ltd.
Bluegon: a polygon‐shaped scatternet formation algorithm for Bluetooth
Authors: Hsieh Tsung‐Wen , Chang Ruay‐Shiung 
Published: January 2006

AbstractBluetooth is one of the cable‐replacement technologies. It uses short‐range radio links to replace connecting cables. Bluetooth enables portable devices to form short‐range wireless ad hoc networks. A set of Bluetooth devices sharing a common channel can form a personal area network called a piconet. Several piconets can also be interconnected to establish a scatternet. Zaruba, Basaghi and Chlamtac proposed a mechanism for forming a distributed scatternet called the Bluetree. The algorithm is based on selecting an arbitrary node serving as the Blueroot. The Blueroot initiates the construction of the Bluetree. Though the algorithm is very simple, there are some weak points. For example, being a tree limits its routing choices. There are also the problems of overloading on the Blueroot and the many master/slave bridges on any routing path. In this paper, we will improve the weaknesses of Bluetree by eliminating the bottleneck in the Blueroot and by reducing the number of bridges to half for almost any path. We call the new algorithm Bluegon since polygons (cycles) will be formed in the scatternet. Simulation results indicate the efficiencies of our algorithm. Copyright © 2006 John Wiley & Sons, Ltd.
Efficient MAC strategies for the IEEE 802.11n wireless LANs
Authors: Xiao Yang 
Published: January 2006

AbstractCurrent IEEE 802.11 wireless local area network (WLAN) standard products can provide up to 54 Mbps raw transmission rate, while non‐standard WLAN products with 108 Mbps have already appeared in the market, and the next generation WLAN will provide much higher transmission rates. However, the medium access control (MAC) was designed for lower data rates, such as 1–2 Mbps, and it is not an efficient MAC. Furthermore, a theoretical throughput limit exists due to overhead and limitations of physical implementations, and therefore increasing transmission rate cannot help a lot. Designing efficient MAC strategies becomes critical and important. In this paper, we introduce and propose a series of efficient MAC strategies to overcome the fundamental overhead, and to improve performance. The protocols and mechanisms include Direct Link Protocol, Without Acknowledgement, Without Retransmissions, Block Acknowledgement Protocol, Concatenation, Packing, Multiple Frame Transmission (versions 1 and 2) and Piggyback. The aim of this paper is to introduce and propose these efficient new MACs not only for current IEEE 802.11 standards (.11a/.11b/.11g), but also for the next generation WLAN with higher speed and higher throughput, especially for IEEE 802.11n. Copyright © 2006 John Wiley & Sons, Ltd.
Performance of group ordered successive interference cancellation for multiuser detection in GSTBC SFH/MC DS‐CDMA system
Authors: Cai Lingyun , Xu Youyun , Zhang Haibin , Song Wentao 
Published: January 2006

AbstractIn this paper, we present a novel group space‐time block coding slow frequency‐hopping multicarrier direct‐sequence code division multiple access (GSTBC SFH/MC DS‐CDMA) system over frequency selective fading channels. The proposed scheme greatly improves the bandwidth‐efficient through assigning the users employing the same frequency‐hopping (FH) pattern. Moreover, the users employing the same FH pattern are assigned into different virtual groups, in which the users are assigned to the different spreading codes, while the users are assigned to the same spreading code in the same virtual group. Then, a novel group detection scheme that we denote by group ordered successive interference cancellation (GOSIC) is presented to suppress the interference between the different virtual groups. Our proposed scheme consists of ordering group at the receiver side in order to maximize the overall system performance, and carrying BLAST‐STBC (LSTBC) detection for the users in the same virtual group. We define and derive the optimal group order based on the post group signal to interference plus noise ratio (PGSINR). We also propose another suboptimal group order in order to overcome the complexity issues. Finally, we compare the performance of our proposed GOSIC with conventional group successive interference cancellation (GSIC), conventional STBC multiuser detection (MUD), and LSTBC‐MUD, and show that significant improvement is introduced. Finally, it is shown that the proposed scheme is robust to the imperfect channel estimation. Copyright © 2006 John Wiley & Sons, Ltd.
Defending against wormhole attacks in mobile ad hoc networks
Authors: Wang Weichao , Bhargava Bharat , Lu Yi , Wu Xiaoxin 
Published: January 2006

AbstractIn ad hoc networks, malicious nodes can deploy wormhole attacks to fabricate a false scenario on the proximity relationship among mobile nodes. A classification of the attacks according to the format of the wormholes is proposed. This forms a basis to identify the detection capability of various approaches. An analysis shows that earlier approaches focus on the prevention of wormholes among neighbors that trust each other. As a more generic approach, we present an end‐to‐end scheme that can detect wormholes on a multi‐hop route. Only the trust between the source and the destination is assumed. The mechanism uses geographic information to detect anomalies in neighbor relations and node movements. To reduce the computation and storage overhead, we present a scheme called cell‐based open tunnel avoidance (COTA) to manage the information. COTA requires a constant space for every node on the path and the computation overhead increases linearly to the number of detection packets. We prove that the savings do not deteriorate the detection capability. Various schemes to control communication overhead are studied. The simulation and experiments on real devices show that the proposed mechanism can be combined with existent routing protocols to defend against wormhole attacks. Copyright © 2006 John Wiley & Sons, Ltd.
Low rate convolutional and turbo codes based on non‐linear cyclic codes
Authors: Souto Nuno , Silva João Carlos , Cercas Francisco , Correia Américo , Rodrigues António 
Published: January 2006

AbstractLow rate convolutional and turbo codes that output non‐linear cyclic (NLC) codewords of lengthn = 2m,mbeing a positive integer, are described. These codes have a very low coding rate, which makes them especially suitable for spread spectrum systems where they can be used for simultaneously achieving error correction and bandwidth expansion. Due to the cyclic properties and codeword length of the component codes, branch metrics can be efficiently computed using the fast Fourier transform (FFT), enabling simple implementation of the encoder and decoder. Among the possible NLC base codes, special attention is given to the Tomlinson, Cercas, Hughes (TCH) codes family due to their good autocorrelation properties. It is shown by simulation that the turbo codes schemes studied usually perform better than traditional turbo codes (in this paper the universal mobile telecommunications system (UMTS), rate 1/3 turbo code was used as a reference). This improvement is accomplished at the cost of bandwidth expansion. One of the advantages of the presented solutions over other low rate codes is their ability to improve the synchronization process at the receiver due to the good autocorrelation properties of the available NLC codes (especially TCH codes). A comparison of performance between the UMTS uplink connection and an equivalent system using the proposed codes for a multiuser scenario in a multipath fading channel is presented showing the possibility of capacity increase when using these codes. Copyright © 2006 John Wiley & Sons, Ltd.
Enabling seamless multimedia wireless access through QoS‐based bandwidth adaptation
Authors: Nasser Nidal , Hassanein Hossam 
Published: January 2006

AbstractEffective support of real‐time multimedia applications in wireless access networks,viz. cellular networks and wireless LANs, requires a dynamic bandwidth adaptation framework where the bandwidth of an ongoing call is continuously monitored and adjusted. Since bandwidth is a scarce resource in wireless networking, it needs to be carefully allocated amidst competing connections with different Quality of Service (QoS) requirements. In this paper, we propose a new framework called QoS‐adaptive multimedia wireless access (QoS‐AMWA) for supporting heterogeneous traffic with different QoS requirements in wireless cellular networks. The QoS‐AMWA framework combines the following components: (i) a threshold‐based bandwidth allocation policy that gives priority to handoff calls over new calls and prioritizes between different classes of handoff calls by assigning a threshold to each class, (ii) an efficient threshold‐type connection admission control algorithm, and (iii) a bandwidth adaptation algorithm that dynamically adjusts the bandwidth of an ongoing multimedia call to minimize the number of calls receiving lower bandwidth than the requested. The framework can be modeled as a multi‐dimensional Markov chain, and therefore, a product‐form solution is provided. The QoS metrics—new call blocking probability (NCBP), handoff call dropping probability (HCDB), and degradation probability (DP)—are derived. The analytical results are supported by simulation and show that this work improves the service quality by minimizing the handoff call dropping probability and maintaining the bandwidth utilization efficiently. Copyright © 2006 John Wiley & Sons, Ltd.
A semi‐definite programming approach to spatial decorrelation of independently polarized signals
Authors: Nordebo Sven , Mohammed Abbas 
Published: January 2006

AbstractA MIMO channel spatial decorrelation scheme based on semi‐definite programming is introduced. As a particular application example, the paper addresses the potential gain of using multiple antennas and MIMO–OFDM techniques in order to increase the bandwidth efficiency in satellite communication systems. In particular, we consider the increase in channel capacity that is possible by exploiting satellite and polarization diversity. A fundamental case is studied with three satellite branches, and where each transmit/receive antenna unit consists of six elemental electric and magnetic dipoles yielding six distinguishable parallel polarization channels per frequency. The numerical examples show that capacity increases linearly on a logarithmic signal‐to‐noise ratio scale where the constant of proportionality is the number of active parallel channels. In this respect, the simultaneous use of triple electric and triple magnetic dipoles has the potential to triple the capacity of an antenna system based on antenna units of single dipoles. Copyright © 2006 John Wiley & Sons, Ltd.
Pharmacological characterization of inhibitory effects of postsynaptic opioid and cannabinoid receptors on calcium currents in neonatal rat nucleus tractus solitarius
Authors: Endoh Takayuki 
Published: January 2006

The profile of opioid and cannabinoid receptors in neurons of the nucleus tractus solitarius (NTS) has been studied using the whole‐cell configuration of the patch clamp technique.
Experiments with selective agonists and antagonists of opioid, ORL and cannabinoid receptors indicated that μ‐opioid, κ‐opioid, ORL‐1 and CB1, but not δ‐opioid, receptors inhibit VDCCs in NTS.
Application of [D‐Ala2, N‐Me‐Phe4, Gly5‐ol]‐enkephalin (DAMGO; μ‐opioid receptor agonist), Orphanin FQ (ORL‐1 receptor agonist) and WIN55,122 (CB1 receptor agonist) caused inhibition of IBa in a concentration‐dependent manner, with IC50's of 390 nM, 220 nM and 2.2 μM, respectively.
Intracellular dialysis of the Gi‐protein antibody attenuated DAMGO‐, Orphanin FQ‐ and WIN55,122‐induced inhibition of IBa.
Both pretreatment with adenylate cyclase inhibitor and intracellular dialysis of the protein kinase A (PKA) inhibitor attenuated WIN55,122‐induced inhibition of IBa but not DAMGO‐ and Orphanin FQ‐induced inhibition.
Mainly N‐ and P/Q‐type VDCCs were inhibited by both DAMGO and Orphanin FQ, while L‐type VDCCs were inhibited by WIN55,122.
These results suggest that μ‐ and κ‐opioid receptors and ORL‐1 receptor inhibit N‐ and P/Q‐type VDCCs via Gαi‐protein βγ subunits, whereas CB1 receptors inhibit L‐type VDCCs via Gαi‐proteins involving PKA in NTS.

British Journal of Pharmacology (2006) 147, 391–401. doi:10.1038/sj.bjp.0706623