bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the use of OFDM radio interface for satellite digital multimedia broadcasting systems
Authors: Cioni S. , Corazza G. E. , Neri M. , Vanelli‐Coralli A. 
Published: March 2006

AbstractThe paper considers the application of Orthogonal Frequency Division Multiplexing (OFDM) techniques in the physical layer of a satellite system devoted to the provision of digital multimedia broadcasting (DMB) services, which are presently the focus of extensive research and development endeavours. In particular, the paper demonstrates that the inherently high spectrum efficiency of OFDM can be retained even in unfavourable propagation channels affected by heavy non‐linear distortion introduced by the on‐board high power amplifier. This encouraging performance is achieved through the proper design and application of coding and pre‐distortion techniques, as described in the paper. Based on these results, the paper considers also the comparison of OFDM and High Speed Downlink Packet Access (HSDPA) techniques. HSDPA is the standardized radio interface for 3G terrestrial mobile networks. Copyright © 2006 John Wiley & Sons, Ltd.
Genotypic and phenotypic variability in cowpea grown in a humid environment in Nigeria
Authors: Nwofia GE , Ene‐Obong EE , Okocha PI 
Published: March 2006

AbstractFrom a study of 108 cowpea genotypes, plant height, dry matter yield, pod length and seeds/pod could be improved by direct selection and these are associated with seed yield. Copyright © 2006 John Wiley & Sons, Ltd
Procedure compilation in the refinement calculus
Authors: Lermer K. , Fidge C. J. 
Published: March 2006

Abstract
High-level language program compilation strategies can be proven correct by modelling the process as a series of refinement steps from source code to a machine-level description. We show how this can be done for programs containing recursively-defined procedures in the well-established predicate transformer semantics for refinement. To do so the formalism is extended with an abstraction of the way stack frames are created at run time for procedure parameters and variables.
Stem turnover strategy of multiple‐stemmed woody plants
Authors: Fujiki Daisuke , Kikuzawa Kihachiro 
Published: March 2006

AbstractWe have investigated stem turnover strategy for Lindera umbellata, an understory shrub that sprouts from its rootstock under natural conditions to replace constituent stems, on the basis of the hypothesis that the multiple‐stemmed form of woody species is an adaptation enabling efficient reproduction in high‐stress environments. We tested the hypothesis that the timing of stem replacement maximizes sexual reproduction for the shrub. We developed a model for the time of optimum replacement of a stem by a daughter stem which maximizes the sexual reproduction of a shrub and tested the model using L. umbellata growing in the field. From the model, the optimum time of replacement of a stem with a daughter stem is when cumulative sexual reproduction per unit time for the stem is maximum. In practice, this will be the last age (topt) at which annual sexual reproduction in a stem can potentially exceed cumulative sexual reproduction per unit time for the stem. Half of the stems died at almost topt and had sexually mature daughter stems at that time. Other stems, however, died at times more remote from topt when daughter stems were sexually immature. It is thought that normal replacement of the latter stems was prevented by accidents such as breakage. We conclude that clumps of L. umbellata achieve efficient sexual reproduction by stem replacement at the optimum time, although accidents can, to some extent, determine when the stem actually dies.
Residues in the first transmembrane domain of theCaenorhabditis elegansGABAAreceptor confer sensitivity to the neurosteroid pregnenolone sulfate
Authors: Wardell Bryan , Marik Purba S , Piper David , Rutar Tina , Jorgensen Erik M , Bamber Bruce A 
Published: March 2006

The GABAAreceptor is a target of endogenous and synthetic neurosteroids. Little is known about the residues required for neurosteroid action on GABAAreceptors. We have investigated pregnenolone sulfate (PS) inhibition of theCaenorhabditis elegansUNC‐49 GABA receptor, a close homolog of the mammalian GABAAreceptor.The UNC‐49 locus encodes two GABA receptor subunits, UNC‐49B and UNC‐49C. UNC‐49C is sensitive to PS but UNC‐49B is not sensitive. By analyzing chimeric receptors and receptors containing site‐directed mutations, we identified two regions required for PS inhibition.Four residues in the first transmembrane domain are required for the majority of the sensitivity to PS, but a charged extracellular residue at the end of the M2 helix also plays a role. Strikingly, mutation of one additional M1 residue reverses the effect of PS from an inhibitor to an enhancer of receptor function.Mutating the M1 domain had little effect on sensitivity to the inhibitor picrotoxin, suggesting that these residues may mediate neurosteroid action specifically, and not allosteric regulation in general.British Journal of Pharmacology(2006)148, 162–172. doi:10.1038/sj.bjp.0706719
The in vivo synaptic plasticity mechanism of EGb 761‐induced enhancement of spatial learning and memory in aged rats
Authors: Wang Yongfu , Wang Lei , Wu Jing , Cai Jingxia 
Published: March 2006

It has not been uniform to date that the Ginkgo biloba extracts enhance cognitive function in aged animals, and the mechanisms of action remain difficult to elucidate. In this study, the Morris water maze task and electrophysiological methods were used to study the effects of repeated daily administration of EGb 761, a standardized extract from G. biloba leaves, on hippocampal‐dependent spatial learning and memory and synaptic plasticity of aged rats.
The adult subjects perform the Morris water maze task better than aged rats, as a cellular mechanism, the hippocampal long‐term potentiation (LTP) elicited from adult animals is robust (139.29±2.7%).
In addition, the spatial learning and memory of aged rats that had been fed on an EGb 761‐supplemented diet (60 mg kg−1) for 30 days were significantly better than those of control aged rats. The magnitude of LTP (116.63±3.6%) recorded in vivo from the hippocampus CA1 area of aged rats was significantly enhanced by EGb 761 (60 mg kg−1).
In conclusion, the spatial learning and memory of aged rats is worse than that of young subjects, and EGb 761, acting as a ‘cognitive enhancer’, has benefit on synaptic plasticity and cognition in aged rats. The present data further confirmed that enhancement of synaptic plasticity of the hippocampus might ameliorate the deficit in spatial learning and memory in aged rats.

British Journal of Pharmacology (2006) 148, 147–153. doi:10.1038/sj.bjp.0706720
Ireland’s National Innovation System: An Exploratory Study of Supporting Institutions and Dynamic Actors
Authors: Pontikakis Dimitrios , McDonnell Thomas , Geoghegan Will 
Published: March 2006

Abstract
This paper begins with a brief look at the literature on national innovation systems (NIS). Building on the NIS approach, we present a simple conceptual framework. National innovative competence is dependent on the presence of dynamic STI actors, operating within the confines of compatible institutions. We distinguish the roles played by different STI actors and argue that heterogeneous actors engage in innovation for different reasons. Collaborative innovation is not always a natural consequence of engagement in innovation but is characterised by a distinct set of considerations. The latter part of the paper is concerned with the application of this conceptual framework to the case of Ireland. We identify the institutions pertaining to Ireland’s current innovative performance. An outline of STI actors according to their role in the system is then presented. In turn we outline the various contributions of Irish STI actors and explore their motives for engaging in innovation and collaborative innovation.
Policy Initiative Dilemmas Surrounding Media Convergence: A Cross National Perspective
1
Authors: Menon Siddhartha 
Published: March 2006

Abstract
The discourse surrounding convergence of mass media content and infrastructures has been fraught with extravagant expectations and rhetoric. This article utilizes a cross‐national perspective and focuses on regulatory aspects of the media convergence issue in order to explore the disconnect between the hype and realities of convergence. Three research questions characterize the relevant existing policy initiatives, identify obstacles to convergence and in comparativist terms ascertain which policy models have been relatively more effective. This paper adopts a case study structure integrating convergence policy models in the US, South Africa, Japan and India.
English Spelling Reform
Authors: Carter James B. 
Published: March 2006

Abstract
Knowledge is the wealth of nations, and language is the main social technology by which knowledge is communicated. An efficient orthography is therefore of great importance. English, as the principal international language of the early twenty‐first century, has much to offer the world, but its spelling is archaic and dysfunctional. Technically, the reform of English spelling would not be difficult, but there are very major political obstacles in the way. The benefits of spelling reform would greatly exceed the costs, and a ‘Big bang’ approach to reform is required. The present article outlines a technical solution and the way in which reform could be implemented.
Identification of an erythroid ATP‐dependent aminophospholipid transporter
Authors: Soupene Eric , Kuypers Frans A. 
Published: March 2006

SummaryThe asymmetric distribution of amino‐containing phospholipids in plasma membranes is essential for the function and survival of mammalian cells. Phosphatidylserine (PS) is restricted to the inner leaflet of plasma membranes by an ATP‐dependent transport process. Exposure of PS on the surface of cells serves as a binding site for haemostatic factors, triggers cell–cell interaction and recognition by macrophages and phospholipases. Exposure of PS on the red cell surface plays a significant role in sickle cell pathology. We report the identification of two different isoforms of the aminophospholipid translocase, Atp8a1, or flippase, in the murine red blood cell membrane.
Homozygous C2362F von Willebrand factor induces intracellular retention of mutant von Willebrand factor resulting in autosomal recessive severe von Willebrand disease
Authors: Tjernberg P. , Castaman G. , Vos H. L. , Bertina R. M. , Eikenboom J. C. J. 
Published: March 2006

SummaryThe missense mutation of cysteine 2362 to a phenylalanine in von Willebrand factor (VWF) has been detected in several Italian families with autosomal recessive, severe von Willebrand disease. We investigated how this amino acid change in VWF may lead to a predominantly quantitative defect. This mutation was studied in vitro by transient expression of the full‐length mutant VWF‐C2362F protein and in vivo by analysis of plasma VWF after infusion of 1‐deamino‐8‐d‐arginine vasopressin (DDAVP) in a patient homozygous for this mutation. Single transfections of pSVHVWF‐C2362F and cotransfections of mutant and wild‐type constructs resulted in 8% and 50% VWF antigen, respectively, in conditioned medium. These reduced levels are in accordance with observations in homozygous and heterozygous carriers of the mutation. In addition, VWF‐C2362F was retained intracellularly. Similar results were obtained for C2362F and C2362A. After infusion of DDAVP in a homozygous patient, a twofold decrease in half‐life of plasma VWF‐C2362F was observed. This was not explained by increased susceptibility of recombinant VWF‐C2362F to ADAMTS13. It was concluded that VWF‐C2362F causes reduced VWF plasma levels due to impaired secretion and intracellular retention. Furthermore, it is the loss of cysteine 2362 rather than the introduction of the bulky amino acid side chain that causes these effects.
Mutagenicity of non‐homologous end joining DNA repair in a resistant subset of human chronic lymphocytic leukaemia B cells
Authors: Deriano Ludovic , Merle‐Béral Hélène , Guipaud Olivier , Sabatier Laure , Delic Jozo 
Published: March 2006

SummaryNon‐homologous end joining (NHEJ) is an important determinant of genomic stability in mammalian cells. This DNA repair pathway is upregulated in a subset of B‐cell chronic lymphocytic leukaemia (B‐CLL) cells resistant to DNA damage‐induced apoptosis. Using an in vitro assay for double‐strand breaks (DSB) end ligation, we studied the fidelity of DSB repair in B‐CLL cells which were resistant or sensitive to in vitro DSB‐induced apoptosis with concomitant patients’ resistance or sensitivity to chemotherapy, respectively. The fidelity of DNA repair was determined by DNA sequencing of polymerase chain reaction products cloned in pGEM‐T vector. Sequence analysis of DNA end junctions showed that the frequency of accurate ligation was higher in sensitive B‐CLL cells and control cell lines, than in resistant cells where end joining was associated with extended deletions. Upregulated and error‐prone NHEJ in resistant cells could be a quite possible mechanism underlying both genomic instability and poor clinical outcome.
Peripartum maternal and foetal ghrelin, growth hormones, IGFs and insulin interrelations
Authors: Fuglsang Jens , Sandager Puk , Møller Niels , Fisker Sanne , Frystyk Jan , Ovesen Per 
Published: March 2006

SummaryObjective  Ghrelin may influence GH secretion and is associated with insulin sensitivity. In pregnancy, placental growth hormone (PGH) replaces GH. The aim of this study was to investigate the relationship between PGH and ghrelin and their relationship to insulin sensitivity in pregnancy.Design  Prospective, descriptive study.Patients  Thirty‐seven singleton pregnant and six twin pregnant womenMeasurements  Maternal blood samples were drawn before and 2 days after elective caesarian section (CS). Serum total ghrelin, PGH, GH, GH‐binding protein, insulin and IGF‐I and IGF‐II, and plasma glucose were determined. Insulin sensitivity indices (ISIs) were calculated. Cord blood samples were drawn at delivery for ghrelin determination.Results  Serum ghrelin only displayed a minimal, although statistically significant, decrease after CS. Prior to delivery serum PGH increased by 25% during fasting, and was undetectable the day after CS. Serum levels of GH were low until 48 h after CS. No significant correlations were detected between PGH or ghrelin and ISIs, although a trend was observed for ghrelin. Twin pregnancies had higher PGH levels than singletons; however, levels of IGFs were similar. In cord blood, ghrelin levels were higher in arterial than venous samples.Conclusions  Maternal ghrelin levels were only minimally affected by parturition, suggesting that maternal ghrelin is not involved in the transition from PGH to GH secretion. The increased arterial ghrelin levels in the foetus suggest foetal ghrelin production. Serum PGH appears to be influenced by fasting. Finally, elevated PGH levels in twin pregnancies do not appear to affect maternal IGF levels.
The effect of abdominal obesity on insulin sensitivity and serum lipid and cytokine concentrations in African women
Authors: Crowther N. J. , Ferris W. F. , Ojwang P. J. , Rheeder P. 
Published: March 2006

SummaryObjectives  Studies have shown clear associations of abdominal obesity with lipid and glucose metabolism and cytokine levels in a number of different population groups. However, no such studies have been performed in an African population in which visceral adipose tissue levels have been shown to be lower than in European subjects.Design and patients  Cross‐sectional analysis in 124 African women.Measurements  Fasting serum samples were taken from all subjects and anthropometric measurements obtained. Blood levels of glucose, insulin, total cholesterol, high‐density lipoprotein (HDL) and low‐density lipoprotein (LDL) cholesterol, triglyceride, interleukin (IL)‐6, IL‐8 and IL‐18 were measured. Subjects were separated into normal and abnormal glucose tolerant groups and into tertiles according to waist circumference (WC). Insulin resistance was assessed using the homeostasis model assessment (HOMA).Results  Abnormal glucose‐tolerant subjects had higher WC, glucose and HOMA levels than the normal glucose‐tolerant group. Increased WC was associated with higher triglyceride, insulin and HOMA levels and lower HDL levels. Multiple regression analyses showed that WC associated positively with HOMA and serum triglyceride levels and negatively with HDL levels. IL18 was a positive but weak determinant of the HOMA level and BMI correlated positively with serum IL‐6 concentrations.Conclusions  Although previous studies have shown that African subjects have a lower visceral adipose depot size than European subjects, abdominal obesity is still associated with insulin resistance and dyslipidaemia. The association between abdominal obesity and metabolic dysfunction within this population is not dependent upon IL‐6, IL‐8 or IL‐18.
Molecular characterization of immunoglobulin D in mammals: immunoglobulin heavy constant delta genes in dogs, chimpanzees and four old world monkey species
Authors: Rogers Kenneth A. , Richardson Jennifer P. , Scinicariello Franco , Attanasio Roberta 
Published: March 2006

SummaryAntibodies are adaptor molecules that neutralize pathogens and link humoral and cellular defence mechanisms. Immunoglobulin D (IgD), one of the five antibody classes present in mammals, is expressed as an antigen receptor on naïve B cells. The functional role that IgD plays in the immune response is still poorly understood, but the recent characterization of immunoglobulin heavy constant delta genes (IGHD) in a variety of species challenges the view that IgD is of minor importance and is not present in many animals. On the basis of serological studies, IgD appears to be expressed in the majority of mammalian species examined. To confirm, at the molecular level, that IgD is present in different species, we cloned and sequenced IGHD cDNA from dogs and five non‐human primate species (chimpanzee, rhesus macaque, cynomolgus macaque, baboon and sooty mangabey). Our results show that in all six species, IgD heavy chains possess three immunoglobulin domains and a long hinge region encoded by two exons. Only the hinge region of non‐human primates is similar to the human hinge region, with conservation of O‐glycosylation sites and multiple charged residues at opposing ends. The preservation of IgD in primates, dogs and previously characterized species suggests an important functional role for IgD, possibly involving binding to a receptor. The high degree of similarity existing between the structural features of human and non‐human primate IgD suggests that non‐human primates are suitable for in vivo studies designed to define the role that IgD plays in the immune response.
NKT cells play critical roles in the induction of oral tolerance by inducing regulatory T cells producing IL‐10 and transforming growth factor β, and by clonally deleting antigen‐specific T cells
Authors: Kim Hyun Jung , Hwang Su Jin , Kim Byoung Kwon , Jung Kyeong Cheon , Chung Doo Hyun 
Published: March 2006

SummaryOral tolerance is the systemic unresponsiveness induced by orally administered proteins. To explore the roles of natural killer T (NKT) cells in oral tolerance, we induced oral tolerance to ovalbumin (OVA) in NKT cell‐deficient mice. In CD1d–/– mice, the induction of tolerance to orally administered high‐ or low‐dose OVA was impaired. Dendritic cells (DCs) in the Peyer's patches (PPs) of CD1d–/– mice fed OVA showed high expression of major histocompatibility complex (MHC) class II and B7 molecules, whereas DCs of control mice fed OVA expressed low levels of these molecules. The adoptive transfer of NKT cells restored oral tolerance and induction of tolerogenic DCs in the PPs and spleens of CD1d–/– mice. Moreover, interleukin (IL)‐10 and transforming growth factor (TGF)‐β1 production in vitro were reduced in cells from the spleen and PPs of CD1d–/– mice compared with those of control mice fed OVA. The numbers of OVA‐specific CD4+ KJ1‐26+ T cells were significantly reduced in the PPs and spleens of DO11·10 mice fed OVA. In contrast, OVA‐specific CD4+ KJ1‐26+ T cells were not deleted in the PPs or spleens of DO11·10 CD1d–/– mice. In conclusion, NKT cells were found to play an indispensable role in oral tolerance by inducing regulatory T cells, and clonally deleting antigen‐specific CD4+ T cells.
Regulatory T cells in human disease and their potential for therapeutic manipulation
Authors: Taams Leonie S. , Palmer Donald B. , Akbar Arne N. , Robinson Douglas S. , Brown Zarin , Hawrylowicz Catherine M. 
Published: March 2006

SummaryRegulatory T cells are proposed to play a central role in the maintenance of immunological tolerance in the periphery, and studies in many animal models demonstrate their capacity to inhibit inflammatory pathologies in vivo. At a recent meeting [Clinical Application of Regulatory T Cells, 7–8 April 2005, Horsham, UK, organized by the authors of this review, in collaboration with the British Society for Immunology and Novartis] evidence was discussed that certain human autoimmune, infectious and allergic diseases are associated with impaired regulatory T‐cell function. In contrast, evidence from several human cancer studies and some infections indicates that regulatory T cells may impair the development of protective immunity. Importantly, certain therapies, both those that act non‐specifically to reduce inflammation and antigen‐specific immunotherapies, may induce or enhance regulatory T‐cell function. The purpose of this review was to summarize current knowledge on regulatory T‐cell function in human disease, and to assess critically how this can be tailored to suit the therapeutic manipulation of immunity.
Evolutionary conservation of neuropeptide expression in the thymus of different species
Authors: Silva Alberto B. , Aw Danielle , Palmer Donald B. 
Published: March 2006

SummaryEvidence suggests that the immune and neuroendocrine systems cross talk by sharing ligands and receptors. Hormones and neuropeptides produced by the neuroendocrine system often modulate the function of lymphoid organs and immune cells. We have previously reported the intrathymic expression of somatostatin (SOM) in the mouse and that several neuropeptides, most notably calcitonin‐gene‐related peptide (CGRP), neuropeptide Y (NPY), SOM and substance P (SP), can modulate thymocyte development. However, little is known about the intrathymic expression of these neuropeptides either in the mouse or in other species. Moreover, a comparative analysis of the expression of these molecules would highlight the evolutionary importance of intrathymic neuroendocrine interactions in T‐cell development. We have studied the expression of different neuropeptides in the thymus of zebrafish, Xenopus, avians, rodent, porcine, equine and human by immunohistochemistry and reverse transcription–polymerase chain reaction. We found that CGRP, NPY, SOM, SP and vasointestinal polypeptide (VIP) are expressed in the thymus of all species investigated. The thymic location of many of these neuropeptides was conserved and appears to be within the stromal compartments. Interestingly, in the avian thymus the expression of CGRP, SOM and SP appears to change depending on the age of the tissue. These findings suggest that neuropeptides may play an important role in T‐cell development and provide further evidence of cross talk between the immune and neuroendocrine systems.