bluuebunny/crossref_metadata_2025 huggingface dataset:
Gender differences in hip adduction motion and torque during a single‐leg agility maneuver
Authors: Hewett Timothy E. , Ford Kevin R. , Myer Gregory D. , Wanstrath Kim , Scheper Melia
Published: January 2006

The purpose of this study was to identify gender differences in hip motion and kinetics during a single leg bidirectional deceleration maneuver. The rationale for the development of this maneuver was to test dynamic hip control during the deceleration of three different types of single‐leg landings. The hypothesis was that female athletes would display increased hip adduction angles and moments during the maneuver compared to male athletes. Thirty‐six collegiate soccer players (19 female, 17 male) volunteered to participate. Subjects were instructed to start the maneuver balancing on one foot, to hop through an agility‐speed ladder on the same leg “up two boxes, back one, and then up one and hold it.” Hip kinematics and kinetics during all three landings were examined. Females demonstrated significantly greater hip adduction angles at initial contact during all three landings and greater maximal hip adduction during landings 1 and 2 compared to male athletes. Females also exhibited significantly increased external hip adduction moments during landing 1, however, no differences were found between genders during landings 2 and 3. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:416–421, 2006
Antibiotic‐containing hyaluronic acid gel as an antibacterial carrier: Usefulness of sponge and film‐formed HA gel in deep infection
Authors: Matsuno Hiroaki , Yudoh Kazuo , Hashimoto Masamichi , Himeda Yasukazu , Miyoshi Teruzo , Yoshida Kaoru , Kano Syogo
Published: January 2006

We have developed a novel bioabsorbable antibacterial carrier using hyaluronic acid (HA) gel for prevention and treatment of orthopedic infections. In this study, we investigated the in vivo antibacterial effects of two forms of this new material, an HA gel sponge and an HA gel film. A titanium cylinder was inserted into the intramedullary cavity of each rabbit femur, along with an HA gel sponge or HA gel film containing antibiotics. The HA gel sponge contained gentamycin, vancomycin, tobramycin, or minomycin. The HA gel film contained gentamycin or vancomycin. After 0, 7, and 14 days, the rabbit bone marrow was collected, and the antibacterial activity of the HA gel was determined by agar diffusion test. As a control, we used Septocoll, a commercially available antibacterial carrier. Both the HA gel sponge and HA gel film exhibited antibacterial activity. The present results indicate that HA gel containing antibiotics is a clinically useful bioabsorbable antibacterial carrier. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:321–326, 2006
Genomic instabilities in squamous cell carcinoma of head and neck from the Indian population
Authors: Chakrabarti Susmita , Sengupta Shiladitya , Sengupta Arunava , Basak Saminendra Nath , Roy Anup , Panda Chinmay , Roychoudhury Susanta
Published: January 2006

Intrinsic genomic instability of an incipient tumor cell drives the development of cancer. In colorectal cancer, an inverse relationship between microsatellite instability (MIN) and chromosomal instability (CIN) has been reported. The relationship between MIN and CIN in head and neck squamous cell carcinoma (HNSCC) is uncertain. In the present study, we examined these two types of instabilities in HNSCC using microsatellite markers and arbitrary primed PCR (APPCR) technique. HNSCC tumors showed high frequency of MIN and loss of heterozygosity (LOH). We observed that, in contrast to colorectal tumors, the frequency of LOH increased with the increase in MIN. There was no significant difference between MIN− and MIN+ groups of HNSCC tumors in the extent of overall genomic alterations; rather higher MIN+ tumors exhibited higher incidence of deletion. Thus, in sporadic HNSCC, both MIN and CIN pathways operate simultaneously to drive tumor formation. © 2006 Wiley‐Liss, Inc.
Lysophosphatidic acid stimulates PC‐3 prostate cancer cell matrigel invasion through activation of RhoA and NF‐κB activity
Authors: Hwang Young Sun , Hodge Jennelle C. , Sivapurapu Neela , Lindholm Paul F.
Published: January 2006

This study was performed to determine the relationship of lysophosphatidic acid (LPA) stimulation and increased Ras homolog A (RhoA) activity to nuclear factor kappa B (NF‐κB) activity, and the role of these factors in regulating prostate cancer cell invasion. PC‐3 high invasive cells demonstrated constitutively increased RhoA, NF‐κB, and in vitro Matrigel invasion which were further induced by LPA stimulation or transfection with constitutively active RhoA Q63E mutant. LPA treatment rapidly and transiently induced RhoA activity followed by maximally increased DNA binding of NF‐κB at 1 h and AP‐1 at 4 h. The LPA‐induced NF‐κB DNA binding was preceded by transient IκBα phosphorylation, and decreased total IκBα levels. Further demonstrating the relationship between RhoA and NF‐κB activation, PC‐3 cells stably transfected with constitutively active RhoA Q63E demonstrated constitutively increased phospho‐IκBα, while PC‐3 cells transfected with dominant negative RhoA N19 exhibited decreased phospho‐IκBα levels. The LPA‐induced Matrigel invasion and NF‐κB DNA binding activity were both inhibited by expression of the RhoA inhibitor C3 exoenzyme or dominant negative mutant NF‐κB inhibitor IκBα S32/36A. Similarly, transfection with dominant negative IκBα S32/36A inhibited PC‐3 RhoA Q63E cell in vitro invasion. Treatment of PC‐3 high invasive and RhoA Q63E cells with sodium salicylate or lactacystin inhibited NF‐κB and invasion, while pyrrolidine dithiocarbamate (PDTC) treatment of PC‐3 high invasive cells inhibited NF‐κB only. Each inhibitor blocked LPA‐induced invasion while PDTC inhibited LPA‐induced NF‐κB and invasion to the greatest extent. These results point to a model where LPA stimulates RhoA and increased PC‐3 prostate cancer cell invasion activity through an NF‐κB‐dependent pathway. © 2006 Wiley‐Liss, Inc.
Comparative expressed sequence hybridization reveals differential gene expression in morphological breast cancer subtypes
Authors: Vanden Bempt Isabelle , Vanhentenrijk Vera , Drijkoningen Maria , Wolf‐Peeters Christiane De
Published: January 2006

In this study, comparative expressed sequence hybridization (CESH) has been used to compare gene expression patterns in three morphologically different breast cancer subtypes: classic‐type invasive lobular carcinoma (ILC), poorly differentiated ERBB2‐negative invasive ductal carcinoma‐not otherwise specified (IDC‐NOS), and poorly differentiated ERBB2‐positive IDC‐NOS. CESH allows global detection of chromosomal regions with differential gene expression in a way similar to that of comparative genomic hybridization (CGH). Eight cases of each breast cancer subtype were included in the study. For each subtype, two pools of four cases each were constructed. CESH was used to compare both pools within the same morphological subtype, followed by a comparison of pools belonging to different subtypes. This revealed three chromosomal regions that were differentially expressed in ductal and lobular carcinomas, including relative overexpression at 8q13–q23 and 16q22, and relative underexpression at 8p21–p22. In addition, an expression signature characterized by relative overexpression at 3q24–q26.3, 14q23–31, 17q12, and 20q12–13 was identified for ERBB2‐positive IDC‐NOS. In summary, CESH analysis highlights chromosomal regions of differential gene expression that are associated with morphologically defined breast cancer subtypes and suggests that regions on chromosome 8 are of interest in the discrimination between ductal and lobular carcinomas. In addition, using CESH, it was possible to identify an ERBB2 expression signature, comprising four chromosomal regions with potential significance in the aggressive behaviour of ERBB2‐positive IDC‐NOS. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Comprehensive genomic analysis of desmoplastic medulloblastomas: identification of novel amplified genes and separate evaluation of the different histological components
Authors: Ehrbrecht A , Müller U , Wolter M , Hoischen A , Koch A , Radlwimmer B , Actor B , Mincheva A , Pietsch T , Lichter P , Reifenberger G , Weber RG
Published: January 2006

Desmoplastic medulloblastoma (DMB) is a malignant cerebellar tumour composed of two distinct tissue components, pale islands and desmoplastic areas. Previous studies revealed mutations in genes encoding members of the sonic hedgehog pathway, including PTCH, SMOH and SUFUH in DMBs. However, little is known about other genomic aberrations. We performed comparative genomic hybridization (CGH) analysis of 22 sporadic DMBs and identified chromosomal imbalances in 20 tumours (91%; mean, 4.9 imbalances/tumour). Recurrent chromosomal gains were found on chromosomes 3, 9 (six tumours each), 20, 22 (five tumours each), 2, 6, 7, 17 (four tumours each) and 1 (three tumours). Recurrent losses involved chromosomes X (eight tumours), Y (six of eleven tumours from male patients), 9, 12 (four tumours each), as well as 10, 13 and 17 (three tumours each). Four tumours demonstrated high‐level amplifications involving sequences from 1p22, 5p15, 9p, 12p13, 13q33‐q34 and 17q22‐q24, respectively. Further analysis of the 9p and 17q22‐q24 amplicons by array‐based CGH (matrix‐CGH) and candidate gene analyses revealed amplification of JMJD2C at 9p24 in one DMB and amplification of RPS6KB1, APPBP2, PPM1D and BCAS3 from 17q23 in three DMBs. Among the 17q23 genes, RPS6KB1 showed markedly elevated transcript levels as compared to normal cerebellum in five of six DMBs and four of five classic medulloblastomas investigated. Finally, CGH analysis of microdissected pale islands and desmoplastic areas showed common chromosomal imbalances in five of six informative tumours. In summary, we have identified several novel genetic alterations in DMBs and provide genetic evidence for a monoclonal origin of their different tissue components. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Practice development and action learning
Authors: Edmonstone John , MacKenzie Hazel
Published: January 2006

This article seeks to explore the potentially fruitful connections between practice development and the approach to personal and organizational development known as action learning. Action learning is defined as: a method for individual and organization development based upon small groups of colleagues meeting over time to tackle real problems or issues in order to get things done; reflecting and learning from their experience and from each other as they attempt to change things (Edmonstone, 2003). The article begins by examining the nature of professional practice and the relationship between theory and practice. It then considers the nature of learning, including an examination of competence and capacity. It reviews action learning and its underlying roots in adult learning, focusing particularly on the concentration of action learning on ‘problems’ rather than ‘puzzles’. It examines the nature of practice development and then explores the relationship between practice development and action learning through material derived from an evaluation study conducted on the Royal College of Nursing Clinical Leadership Programme in Scotland where action learning forms a major element of the programme. Copyright © 2005 Whurr Publishers Ltd.
Practice development: ‘plausibility’, ‘doability’ and ‘outcome’ issues
Authors: Carr Susan M
Published: January 2006

There is a dearth of literature exposing the systems, processes and roles involved in practice development activity. This paper addresses this deficit by proposing a framework derived from research to facilitate setting the aim and enabling the process of practice development. Based on the theories of change approach, the context of the development is a key component of the process. The method of articulating the rationale guiding the activity ensures that it is both ‘plausible’ and ‘doable’ thereby enhancing the likelihood of a successful outcome. Copyright © 2005 Whurr Publishers Ltd.
Proteomic analysis of cellular change involved in mitochondria‐to‐nucleus communication in L6 GLUT4myc myocytes
Authors: Park Seung Yoon , Lee Sanghyun , Park Kyong Soo , Lee Hong Kyu , Lee Wan
Published: January 2006

Genetic or biochemical abnormalities in mitochondria are closely associated with apoptosis, aging, cancer, and other chronic degenerative diseases. Mitochondrial dysfunction resulting from mitochondrial DNA (mtDNA) depletion dispatches retrograde signals to the nucleus to compensate by altering the expression of various genes. In this study, a proteomic approach was used to gain insight into the nuclear gene targets of mitochondrial stress signaling and the pathophysiological mechanisms associated with mitochondrial dysfunction. We have used 2‐DE to characterize the nuclear gene responses resulting from mtDNA depletion in L6 GLUT4myc myocytes. Our results showed that 77 polypeptides were differentially expressed in mtDNA‐depleted cells; 33 polypeptides were down‐regulated and 44 polypeptides were up‐regulated. Of these differentially expressed polypeptides, 40 were identified as 36 different proteins by MALDI‐TOF MS. These proteins are related to various cellular responses, such as apoptosis, cellular metabolism, signaling and cytoskeleton functions. It is suggested that the insulin resistance developed in mtDNA‐depleted myocytes may be associated with disorganization of cytoskeleton assembly, and that cellular mtDNA depletion might promote the ability to evade apoptosis or other death effectors.
High‐throughput analysis of GST‐fusion protein expression and activity‐dependent protein interactions on GST‐fusion protein arrays with a spectral surface plasmon resonance biosensor
Authors: Jung Jae‐Wan , Jung Se‐Hui , Kim Hyun‐Soo , Yuk Jong Seol , Park Jae‐Bong , Kim Young‐Myeong , Han Jeong‐A , Kim Pyung‐Hyun , Ha Kwon‐Soo
Published: January 2006

We modified gold arrays with a glutathione (GSH) surface, and investigated high‐throughput protein interactions with a spectral surface plasmon resonance (SPR) biosensor. We fabricated the GSH exterior on gold surfaces by successive modification with aminoethanethiol, 4‐maleimidobutyric acid N‐hydroxysuccinimide ester and GSH. We immobilized GST‐Rac1, GST‐RhoA, the GST‐Rho‐binding domain of rhotekin and the GST‐p21‐binding domain of PAK1 onto the GSH surface, and observed specific antigen‐antibody interactions on the GST‐fusion protein arrays. We determined the expression of GST‐fusion proteins in Escherichia coli on the GSH surface with the SPR biosensor. We then analyzed the interactions of tissue transglutaminase (tTGase), a Ca2+‐dependent enzyme, with RhoA and Rac1 on the GST‐fusion protein arrays with the SPR biosensor. We found that tTGase interacted with RhoA and Rac1 in a Ca2+‐dependent manner, indicating that the interactions were dependent on tTGase activity. In addition, transamidation of Rac1 by tTGase was dependent on Ca2+ concentration. We obtained similar results with GST pull‐down assays. Thus, protein arrays prepared on the GSH surface provide a useful system for the high‐throughput analysis of GST‐fusion protein expression and activity‐dependent protein interactions with the spectral SPR biosensors.
Loss of transgelin in repeated bouts of ulcerative colitis‐induced colon carcinogenesis
Authors: Yeo Marie , Kim Dong‐Kyu , Park Hee Jin , Oh Tae Young , Kim Jang Hee , Cho Sung Won , Paik Young‐Ki , Hahm Ki‐Baik
Published: January 2006

Though ulcerative colitis (UC)‐associated colon cancer develops from dysplastic lesions caused by chronic inflammation, the specific mechanistic link between chronic inflammation and carcinogenesis in colon has not been integrated into molecular understanding. We therefore established an experimental animal model for colitic cancer, and used proteomic analysis, based on 2‐DE and MALDI‐TOF MS, to identify proteins involved in colitic cancer. In our model, 6‐week‐old C57BL/6J mice were exposed to 15 cycles of dextran sodium sulfate (DSS), with each cycle consisting of 0.7% DSS for 1 week followed by distilled water for 10 days. Colorectal tumors developed in 22 of 24 mice (91.6%), with a tumor multiplicity of 1.727 per tumor‐bearing mouse. Comparative 2‐DE analysis showed that 38 protein spots were differentially expressed in colon tumors and normal colon. We identified 27 of these proteins, including GRP94, HSC70, enolase, prohibitin, and transgelin. The reduction of transgelin expression in mouse colon tumors was confirmed by Western blotting and immunohistochemistry. We also found that transgelin expression was significantly reduced in human colon tumors compared with adjacent nontumorous tissues. In conclusion, these results suggest that loss of transgelin could be a candidate for biomarker of repeated colitis‐associated colon cancer.
Human Disease Glycomics/Proteome Initiative Workshop and the 4th HUPO Annual Congress
Authors: Taniguchi Naoyuki , Nakamura Kazuyuki , Narimatsu Hisashi , von der Lieth Claus‐Willi , Paulson James
Published: January 2006

At the Human Disease Glycomics/Proteome Initiative workshop held on August 27 on the occasion of the fourth HUPO Congress in Munich, Germany, the working groups reported on pilot studies, performed by 21 laboratories world‐wide, to analyze glycan using MS. During the steering committee on July 31 in Osaka, Japan, it was reported that these groups have developed a system using MS to assess the world‐wide network on the screening of congenital disorders of glycosylation. The concept of glycobioinformatics was also explained at this meeting. The session on PTMs laid particular emphasis on the importance of functional glycomics using glycosyltransferase genes as well as on the importance of identifying the target protein(s) carrying the sugar chains.
Guidelines for the next 10 years of proteomics
Authors: Wilkins Marc R. , Appel Ron D. , Van Eyk Jennifer E. , Chung Maxey C. M. , Görg Angelika , Hecker Michael , Huber Lukas A. , Langen Hanno , Link Andrew J. , Paik Young‐Ki , Patterson Scott D. , Pennington Stephen R. , Rabilloud Thierry , Simpson Richard J. , Weiss Walter , Dunn Michael J.
Published: January 2006

In the last ten years, the field of proteomics has expanded at a rapid rate. A range of exciting new technology has been developed and enthusiastically applied to an enormous variety of biological questions. However, the degree of stringency required in proteomic data generation and analysis appears to have been underestimated. As a result, there are likely to be numerous published findings that are of questionable quality, requiring further confirmation and/or validation. This manuscript outlines a number of key issues in proteomic research, including those associated with experimental design, differential display and biomarker discovery, protein identification and analytical incompleteness. In an effort to set a standard that reflects current thinking on the necessary and desirable characteristics of publishable manuscripts in the field, a minimal set of guidelines for proteomics research is then described. These guidelines will serve as a set of criteria which editors of PROTEOMICS will use for assessment of future submissions to the Journal.
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

Poly[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

ABS/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

An 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

Preeclampsia 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

This 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

A 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

In 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

In 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

Bluetooth 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

Current 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

In 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

In 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

Low 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

Effective 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

A 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.
Relative importance of protozoan functional groups in three marine sublittoral areas
Authors: Fernandez-Leborans Gregorio
Published: January 2006

The composition in terms of protozoan functional groups of three sublittoral areas (Castro Urdiales, Santoña and Isla) in the Cantabrian Sea was analysed. The different protozoan species were identified, and their density and biomass was measured. The pigmented protozoa were the most important group in the three areas throughout the year, followed by the bacterivores in Castro Urdiales and Santoña, and the non-selectives in Isla. Bacterivores constituted the most significant group in terms of biomass, after which came that of non-selectives. The parameters with the strongest influence on distribution in functional groups (respect to biomass) were pH, phosphate, organic matter and bacterial biomass, other significant factors being salinity, nitrate and mean grain size. Functional groups expressed as number of species were affected principally by phosphate, pH and, to a lesser extent, temperature and salinity. Statistical analysis using the present data, data regarding functional groups from previous studies in the same areas, and data from other areas, indicate that marine areas show similar characteristics. In the areas covered by the present study, there was a decrease in the number of algivore species and a rise in non-selective species, while bacterivores and pigmented protozoa maintained similar values. In comparison, freshwater areas showed noticeably lower percentages of algivore species and a significantly higher number of bacterivore species.
Ecology of a parasitic barnacle, Koleolepas avis: relationship to the hosts, distribution, left–right asymmetry and reproduction
Authors: Yusa Yoichi , Yamato Shigeyuki , Marumura Masahiro
Published: January 2006

The pedunculate barnacle Koleolepas avis is a symbiont of the sea anemone Calliactis japonica, which lives on gastropod shells carried by large hermit crabs, usually Dardanus arrosor. Relationships with the host sea anemone, distribution on the gastropod shell, left–right asymmetry and reproduction of the barnacle were investigated. A larger number of barnacles occurred on shells with greater ‘cylindroid dimensions’ of sea anemones. Distribution of barnacles on shells was not random: assuming the in situ position of the shell carried by the hermit crab (∼45° inclination), there were more barnacles along the lower part of the anemone disk than the upper part. Large barnacles lie on either the left or right sides of their capitula, and those lying on the left side (Type L individuals) tended to occur along the left side of the host, and those on the right side (Type R) along the right side. Barnacles [ges ]0·016 g in wet weight had egg masses, and there was a positive relationship between body weight and number of eggs. Koleolepas avis has both hermaphrodites and dwarf (complementary) males attached to them. Large hermaphrodites tended to have larger dwarf males than smaller hermaphrodites.
Corralling of larvae in the deep sea
Authors: Van Dover Cindy Lee , Jenkins Cheryl D. , Turnipseed Mary
Published: January 2006

Large numbers of small individuals (pediveligers and juveniles <5 mm) are routinely recorded in size–frequency distributions of mussel samples collected from deep-sea chemosynthetic environments. If recruitment of invertebrates to deep-sea hydrothermal vent sites were via long-distance dispersal, as is typically assumed, one would expect recruitment ‘events’ recorded in size–frequency distributions to be difficult to detect, due to loss of larvae in an open system over large distances. If one imposes mesoscale oceanographic phenomena that minimize dilution of larvae (such as eddies shed from hydrothermal vent plumes) and episodic spawning, expression of this mesoscale corralling at the level of population structure would likely be limited to discrete records of recruitment events encountered serendipitously during haphazard sampling in space and time. The ubiquity of large numbers of post-larvae in mussel samples from a number of disparate sites is likely not serendipitous, but instead may reflect the importance of local sources and sinks of propagules in maintenance of mussel populations.
Food preferences of the sea urchin Diadema antillarum in Gran Canaria (Canary Islands, central-east Atlantic Ocean)
Authors: Tuya F. , Martín J.A. , Reuss G.M. , Luque A.
Published: January 2006

Preferences of the sea urchin Diadema antillarum (Echinodermata: Echinoidea) feeding on five species of brown macroalgae (Padina pavonica, Dyctiota dychotoma, Cystoseira abies-marina, Lobophora variegata and Halopteris filicina) have been studied using caging field experiments on Gran Canaria Island during August to October 2000. Results of three assays of both single and multiple diet experiments rejected the null hypothesis that Diadema does not feed selectively on the five selected algal species. In the multiple diet assays, Diadema consumed an average of 68–98 mg algae urchin−1 h−1 and 4–120 mg algae urchin−1 h−1 in the single diet experiments. On the basis of consumption, the five species of algae eaten can be divided into three groups. Thus Halopteris, Lobophora and Dyctiota were considered preferred algae, while Padina was considered an intermediate alga. Finally Cystoseira was significantly the less preferred and consumed seaweed in all sets of assays.
Length–weight relationships for 18 Lessepsian (Red Sea) immigrant fish species from the eastern Mediterranean coast of Turkey
Authors: Taskavak Ertan , Bilecenoglu Murat
Published: January 2006

Length–weight relationships were estimated for 18 Red Sea immigrant fish species from the eastern Mediterranean coasts of Turkey. The values of the exponent b in the length–weight regression (W= aLb) ranged between 2·482 and 3·355. The median value was 3·018 and 50% of the values ranged between 2·835 and 3·121.
International Toleration: Rawlsian versus Cosmopolitan
Authors: TAN KOK-CHOR
Published: January 2006

How should liberal societies respond to nonliberal ones? In this paper I examine John Rawls's conception of international toleration against what is sometimes called a cosmopolitan one. Rawls holds that a just international order should recognize certain nonliberal societies, to which he refers as decent peoples, as equal members in good standing in a just society of peoples. It would be a violation of liberalism's own principle of toleration to deny the international legitimacy of decent peoples who, among other things, affirm human rights and accept peaceful coexistence with other societies. According to the cosmopolitan idea of international toleration, on the contrary, only societies that are liberal in character meet the criteria for toleration. I suggest that, against the Rawlsian conception of international toleration, the cosmopolitan idea is more consistent with the fundamentals of liberal political morality. I then clarify the ways in which cosmopolitan toleration is not worryingly interventionist even as it is not altogether toothless; and I end with some reflections on why cosmopolitism is not morally imperialistic.