bluuebunny/crossref_metadata_2025_split huggingface dataset:
Capacity analysis and optimisation of OFDM with distortionless PAPR reduction
Authors: Tsouri Gill R. , Wulich Dov 
Published: September 2008

AbstractWe analyse the impact of distortionless peak‐to‐average power ratio (PAPR) reduction methods on the ergodic capacity of orthogonal frequency division multiplexing (OFDM) systems in AWGN and frequency selective channels. We consider the following tradeoff: decreasing PAPR increases the efficiency of the linear power amplifier (PA), yielding an increase in the average power emitted and consequentially an increase in capacity. However, implementing distortionless PAPR reduction methods requires the allocation of power and/or bandwidth, which causes a decrease in capacity. We evaluate this tradeoff by deriving a lower bound on the required increase in PA efficiency to achieve capacity gain, and an expression for the achievable increase in PA efficiency. We resolve this tradeoff by optimising key method parameters to achieve maximal ergodic capacity. We apply the analysis to three representative methods: selected mapping (SLM), tone reservation (TR) and tone injection (TI). Their corresponding optimal number of candidates, number of reserved tones and constellation sizes are derived as a function of channel conditions. We demonstrate how capacity could be lost in common practical scenarios, and suggest practical means for achieving capacity gains which are very close to optimal for each representative method. The analysis may be applied to other PAPR reduction methods as well. Copyright © 2008 John Wiley & Sons, Ltd.
EGFR genetic heterogeneity of nonsmall cell lung cancers contributing to acquired gefitinib resistance
Authors: Jiang Shi‐Xu , Yamashita Kazuya , Yamamoto Michiko , Piao Chun‐Ji , Umezawa Atsuko , Saegusa Makoto , Yoshida Tsutomu , Katagiri Masato , Masuda Noriyuki , Hayakawa Kazushige , Okayasu Isao 
Published: September 2008

AbstractGefitinib is dramatically effective for nonsmall cell lung cancers (NSCLCs) with activating mutations of the epidermal growth factor receptor (EGFR) gene, but these tumors eventually develop drug resistance, attributable to a secondary T790M mutation or acquired MET amplification in some relapsed tumors. We analyzed EGFR mutations in matched pre‐ and post‐therapeutic tumors of 6 gefitinib‐responding lung cancers. With conventional PCR‐based sequencing, classic mutations were detected in pretreatment samples of each case. The same mutations were readily confirmed in treated lesions of 4 cases, but were absent in those of Cases 1 and 2. Subsequent mutant‐enriched peptide‐nucleic‐acid‐mediated PCR clamping and subcloning assays detected the mutation in minor cells of treated lesions of Case 1, but still failed to detect a mutation in Case 2. We thus performed microdissection‐based cell cluster mutation analysis of pretreatment tumors, and found that 3, including the first 2, concurrently contained tumor cells with either mutant or wild‐type EGFR, although the latter was only a minor fraction. These findings suggest that some NSCLCs are genetically heterogeneous with regard to EGFR mutations; gefitinib‐sensitive mutants decrease or vanish while wild clones selectively survive with gefitinib treatment. In addition, T790M was detected in a small fraction of treated lesions of 3 cases, and MET amplification was revealed in 3 treated tumors of Case 2. Thus, our results suggest that multiple mechanisms underlie acquired gefitinib resistance, and selection on a background of EGFR genetic heterogeneity also contributes to acquisition of resistance in a proportion of NSCLCs. © 2008 Wiley‐Liss, Inc.
The anhydrofructose pathway of glycogen catabolism
Authors: Yu Shukun 
Published: September 2008

AbstractIn many living forms, glucose is stored in the polymeric form of glycogen and starch as a source of carbon and energy. Upon need, these polymers are broken down to their building block glucose in the presence of water and hydrolases, and glucose 1‐phosphate in the presence of phosphate and phosphorylase. In the last decade, we established an alternative glycogen catabolic pathway, the so‐called Anhydrofructose (AF) pathway, the description of which was approved by IUBMB in 2006. It is a pathway on the formation of an array of secondary metabolites from glycogen via the central intermediate 1,5‐anhydro‐D‐fructose (AF). Furthermore, we demonstrated the occurrence of this pathway in both eukaryota and prokaryota. Metabolites of this pathway have been identified in mammals including humans. In this review, the physiological and molecular functions of these metabolites in the AF pathway as well as its regulation are discussed. © 2008 IUBMB IUBMB Life, 60(12): 798–809, 2008
Ramachandran‐type plots for glycosidic linkages: Examples from molecular dynamic simulations using the Glycam06 force field
Authors: Salisburg Amanda M. , Deline Ashley L. , Lexa Katrina W. , Shields George C. , Kirschner Karl N. 
Published: September 2008

AbstractThe goals of this article are to (1) provide further validation of the Glycam06 force field, specifically for its use in implicit solvent molecular dynamic (MD) simulations, and (2) to present the extension of G.N. Ramachandran's idea of plotting amino acid phi and psi angles to the glycosidic phi, psi, and omega angles formed between carbohydrates. As in traditional Ramachandran plots, these carbohydrate Ramachandran‐type (carb‐Rama) plots reveal the coupling between the glycosidic angles by displaying the allowed and disallowed conformational space. Considering two‐bond glycosidic linkages, there are 18 possible conformational regions that can be defined by (α, ϕ, ψ) and (β, ϕ, ψ), whereas for three‐bond linkages, there are 54 possible regions that can be defined by (α, ϕ, ψ, ω) and (β, ϕ, ψ, ω). Illustrating these ideas are molecular dynamic simulations on an implicitly hydrated oligosaccharide (700 ns) and its eight constituent disaccharides (50 ns/disaccharide). For each linkage, we compare and contrast the oligosaccharide and respective disaccharide carb‐Rama plots, validate the simulations and the Glycam06 force field through comparison to experimental data, and discuss the general trends observed in the plots. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009
Metal–ligand solution equilibria studied by electrospray ionization mass spectrometry: effect of instrumental parameters
Authors: Di Marco Valerio B. , Bombi G. Giorgio , Zambon Stefano , Traldi Pietro 
Published: September 2008

AbstractElectrospray ionization mass spectrometry (ESI‐MS) is being increasingly employed in the study of metal–ligand equilibria in aqueous solution. In the present work, the ESI‐MS spectral changes due to different settings of the following instrumental parameters are analyzed: the solution flow rate (FS), the nebulizer gas flow rate (FG), the sprayer potential (E), and the temperature of the entrance capillary (T). Twenty‐eight spectra were obtained for each of six samples containing aluminum(III) and 2,3‐dihydroxypyridine at various pH, in the absence or in the presence of a buffer and of sodium ions. Among the considered instrumental parameters, T produced the largest effects on the ionic intensities. FS and FG affected the ESI‐MS spectra to a lower extent than T. In the investigated conditions E had the weakest effects on the spectra.The correlations observed between the ionic intensities and these instrumental parameters were interpreted considering the presence of three kinds of perturbations occurring in the ESI‐MS ion source: formation of some dimers in the droplets, different transfer efficiencies from the droplets to the gas phase for different complexes (according to their surface activity), and subsequent partial thermal decomposition of the dimers and of one of the monomeric complexes in the gas phase. Our results show that the evaluation of the effects produced in the ESI‐MS spectra by a change of instrumental parameters can allow to identify the perturbations occurring when metal–ligand solutions are studied by ESI‐MS. Copyright © 2008 John Wiley & Sons, Ltd.
Improving the reproducibility of Pseudomonas aeruginosa swarming motility assays
Authors: Tremblay Julien , Déziel Eric 
Published: September 2008

AbstractSwarming motility is a rapid and coordinated migration of a bacterial population across a semi‐solid surface. This multicellular phenomenon is getting increasing attention as it is suspected to be related to biofilm development of Pseudomonas aeruginosa. Published swarm plate preparation protocols differ greatly from one study to another and no reproducible and standardized protocols have been proposed to accurately study this phenomenon. We report here a rapid and highly reproducible swarm plate protocol for P. aeruginosa and show how different key parameters affect this type of motility (i.e. agar %, drying time under laminar flow, incubation temperature and pH). Results reported here will help to standardize swarming motility assays and develop effective swarm plate protocols for other bacterial species. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Retracted: A catechol type siderophore, bacillibactin: biosynthesis, regulation and transport in Bacillus subtilis
Authors: Raza Waseem , Wu Hongsheng , Shah Muhammad Ali Abdullah , Shen Qirong 
Published: September 2008

AbstractRetraction: The following article from the Journal of Basic Microbiology, “A catechol type siderophore, bacillibactin: biosynthesis, regulation and transport in Bacillus subtilis” by Waseem Raza, Hongsheng Wu, Muhammad Ali Abdullah Shah and Qirong Shen, published online on 11 September 2008 in Wiley InterScience (www.interscience.wiley.com), has been retracted by agreement between the authors, the journal Editor‐in‐Chief, Erika Kothe, and the publisher Wiley‐VCH. The retraction has been agreed due to substantial overlap of the content of this article with previously published articles in other journals.The Journal of Basic Microbiology apologises to our readership
Physiological and morphological characterization of tert ‐butylhydroperoxide tolerant Candida albicans mutants
Authors: Fekete Andrea , Pócsi Imre , Emri Tamás , Gyetvai Ágnes , Gazdag Zoltán , Pesti Miklós , Karányi Zsolt , Majoros László , Gergely Lajos , Pócsi István 
Published: September 2008

Abstracttert ‐Butylhydroperoxide (t BOOH) tolerant Candida albicans mutants developed from clinical isolates were characterized with increased tolerance of the oxidative stress generating agents t BOOH and H2O2, continuous induction of the antioxidative defence system, reduced pseudohypha and hypha‐forming capabilities, decreased phospholipase secretion and delayed growth in Sabouraud dextrose agar and broth media. Changes in antimycotic (fluconazole, voriconazole, amphotericin B, 5‐fluorocytosine) tolerances as well as in total and cytochrome c‐dependent respirations showed versatile patterns, meanwhile the intensified alternative oxidase‐dependent respiration of the mutants indicated that this respiratory pathway was an important element of the antioxidative defence in general. Because the phenotypes of increased oxidative stress tolerance and reduced virulence attribute production always emerged concomitantly in t BOOH‐tolerant mutants the natural selection of C. albicans strains more tolerant of oxidative stress is unlikely. Not surprisingly, a screening study failed to detect any C. albicans strains with increased oxidative stress tolerance among 46 randomly selected clinical isolates. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermo‐hydrological modelling of the climate change effect on water availability in two hydrologic regions of Mexico
Authors: Mendoza V. M. , Villanueva E. E. , Garduño R. , Nava Y. , Santisteban G. , Mendoza A. S. , Oda B. , Adem J. 
Published: September 2008

AbstractFrom the climatologic data bases (SICLIM and CLICOM) built by the Servicio Meteorológico Nacional (SMN) of Mexico, we have defined two normals: one called Period I, from 1950 to 1975, and the other called Period II, from 1976 to 2000. The objective of the present work is to make an estimation of the annual volume of superficial available water in Periods I and II, and the changes between them, in two important hydrologic regions of Mexico, called Lerma‐Santiago‐Pacifico (HR‐LSP) and Balsas (HR‐B), whose population annually demands almost one‐third of the water extracted in all the country.For this purpose, a non‐linear thermo‐hydrological model is used. It consists of two equations applied to the soil, i.e. the thermal energy and water balance equations, which are coupled through the soil temperature and soil moisture.The results show that the change from Period I to Period II was more significant in the HR‐B than in the HR‐LSP. In the HR‐LSP, the conditions of aridity were favoured by a decrease of 3.4% in the precipitation, which affected almost the entire region.On the average, the HR‐B experienced an increase of 7.0% in precipitation, and therefore, a considerable increase in the volume of available water from Period I to Period II. However, in the northern part of this region, the increase in temperature and the decrement in precipitation reduced water availability, while the opposite occurred in the south of the region, where the decrease of the temperature and the increase in the precipitation increased the available water and favoured conditions of humidity in Period II. Copyright © 2008 Royal Meteorological Society
Radiocarbon dating of charcoal from tropical sequences: results from the Niah Great Cave, Sarawak, and their broader implications
Authors: Higham Thomas F. G. , Barton Huw , Turney Chris S. M. , Barker Graeme , Ramsey Christopher Bronk , Brock Fiona 
Published: September 2008

AbstractSubsamples of charcoal from a number of different excavation contexts at the early modern human (Homo sapiens) site of Niah Great Cave (Malaysia) were accelerator mass spectrometry (AMS) 14C dated. Samples were prepared using one of a number of different methods: untreated (control); acid–base–acid (ABA); and acid–base–wet oxidation with stepped combustion (ABOX‐SC) after Bird et al. (1999). The results show that for material younger than ∼25 ka BP there is little difference between the two chemical pretreatment methods and the control. For charcoal beyond ∼25 ka BP, however, there are differences of up to 4000 a, with ABOX‐SC ages being consistently older. This is argued to be a more effective pretreatment method for decontaminating charcoal samples prior to radiocarbon dating. For radiocarbon dating charcoals greater than ∼25 ka BP, the ABOX‐SC pretreatment and combustion approach appears to be the most rigorous method for developing a robust chronological framework for tropical sequences and should be more widely applied in contexts where the material being dated is likely to be ancient. The new chronology developed for Niah Cave based on this technique suggests that the earliest human evidence dates back to at least 45 ka BP and may extend significantly earlier than this based on the recent discovery of lithics 50 cm below the earliest dated charcoal. Copyright © 2008 John Wiley & Sons, Ltd.
S‐Allyl cysteine, S‐ethyl cysteine and S‐propyl cysteine alleviate oxidative stress‐induced damage within PC12 cells
Authors: Chen Chiu‐mei , Yin Mei‐chin 
Published: September 2008

AbstractBACKGROUND: The PC12 cell line is a suitable model for the investigation of neurodegenerative diseases. In this study, PC12 cells were used to examine in vitro antioxidative and antiapoptotic protection by S‐allyl cysteine (SAC), S‐ethyl cysteine (SEC) and S‐propyl cysteine (SPC). PC12 cells were treated with these agents at 5 and 10 µmol L−1 before exposure to hydrogen peroxide (H2O2).RESULTS: H2O2 treatment significantly decreased mitochondrial membrane potential (MMP) and cell viability and increased lactate dehydrogenase (LDH) release and DNA fragmentation (P < 0.05). The pre‐treatments with SAC, SEC and SPC significantly and concentration‐dependently elevated cell viability and MMP and lowered LDH release and DNA fragmentation (P < 0.05). H2O2 treatment also significantly increased levels of malondialdehyde (MDA), reactive oxygen species (ROS) and oxidised glutathione (GSSG) and decreased glutathione (GSH) content (P < 0.05). The pre‐treatments with SAC, SEC and SPC significantly decreased subsequent H2O2‐induced formation of MDA, ROS and GSSG (P < 0.05) and also alleviated H2O2‐induced GSH depletion (P < 0.05). Finally, H2O2 treatment significantly decreased Na+‐K+‐ATPase activity and elevated caspase‐3 activity (P < 0.05). The pre‐treatments with SAC, SEC and SPC significantly attenuated H2O2‐induced Na+‐K+‐ATPase activity reduction and caspase‐3 activity elevation (P < 0.05).CONCLUSION: The results obtained support that the three cysteine‐containing compounds studied are potent neuroprotective agents. Copyright © 2008 Society of Chemical Industry
A model of traveller acceptance of mobile technology
Authors: Kim Dae‐Young , Park Jungkun , Morrison Alastair M. 
Published: September 2008

AbstractWith the growing popularity of mobile technology, mobile communications are becoming an important channel for tourism organisations. This study builds upon a conceptual framework that explains the factors influencing tourist acceptance of mobile devices. To represent the uniqueness of mobile technology acceptance based on an extensive literature review on user technology acceptance, this study proposes two external variables (technology experience and trip experience) and two influential determinants (perceived usefulness and perceived ease of use). These factors together determine user attitudes towards using mobile devices and, consequently, influence user intention and willingness to adopt mobile devices in the tourism context. The results of a confirmatory factor analysis and structural equation modelling showed that trip experience and technology experience positively influenced perceived performance and perceived ease of use, and the factors positively related to travellers' attitudes towards using mobile devices and intention to use them within the tourism context. Copyright © 2008 John Wiley & Sons, Ltd.
Tour guiding, organisational culture and learning: lessons from an entrepreneurial company
Authors: Lugosi Peter , Bray Jeffery 
Published: September 2008

AbstractThis paper examines the impacts of organisational culture on the learning and development of tour guides. Drawing on a case study of a small entrepreneurial tour company, the paper considers the nature of the organisation's culture, the tours it provides, including their narrative contents and the processes of organisational learning and socialisation. The paper suggests that the development of a learning culture within such an organisation may benefit from the provision of appropriate learning opportunities among the guides and facilitators who coordinate guide development. Copyright © 2008 John Wiley and Sons, Ltd.
The influence of triacylglycerol structure on the oxidative stability of polyunsaturated oils
Authors: Wijesundera Chakra 
Published: September 2008

AbstractThere is a growing trend in the use of unsaturated oils in food products and applications. This stems from mounting scientific evidence and increasing consumer awareness of detrimental health effects of dietary saturated fats and trans fats. A major problem with unsaturated oils is that they oxidise very readily forming compounds that impart off‐flavours to food. Susceptibility of oils to oxidation is often discussed in terms of the degree of unsaturation in the component fatty acids. However, the way in which the unsaturated fatty acids are located within the triacylglycerol molecules (positional distribution) can also influence oxidative stability. This paper reviews the literature on the subject.
Why is LDL‐cholesterol bad cholesterol?
Authors: Stanley John C. 
Published: September 2008

AbstractThe high circulating LDL‐cholesterol levels seen in the inherited disease familial hypercholesterolaemia cause high rates of cardiovascular disease whereas the low circulating LDL‐cholesterol levels following statin treatment cause low rates of cardiovascular disease. This is why LDL‐cholesterol is referred to as bad cholesterol by the media. Atherosclerosis is caused not by native circulating LDL particles but rather by oxidized LDL particles in the arterial wall. Oxidized LDL particles unlike native particles are taken up by macrophages via scavenger receptors to form foam cells and are treated as autoantigens by the immune system provoking inflammation. Hence many of the characteristics of the atherosclerotic plaque including its tendency to rupture and cause thrombosis and heart attacks can be explained in molecular detail by the effects of oxidized LDL particles.
PASER – particle acceleration by stimulated emission of radiation: theory, experiment, and future applications
Authors: Banna S. , Mizrahi A. , Schächter L. 
Published: September 2008

AbstractWe review the theory and the experimental demonstration of one of the novel advanced particle acceleration techniques dubbed PASER ‐ for particle acceleration by stimulated emission of radiation. In such an acceleration paradigm, bundles of electrons are accelerated using the same principle as in laser. A proof‐of‐principle experiment, conducted at the Brookhaven National Laboratory, demonstrated this novel acceleration scheme. A 45 MeV electron macrobunch was modulated by a high‐power CO2laser in a wiggler, and then injected into an excited CO2gas mixture. The emerging microbunches reveal a 0.15 % relative change in the kinetic energy in less than 40 cm long interaction region. This is the first experimental demonstration of coherent collisions of the second kind. The fundamental physics underlying the PASER paradigm is discussed via the analysis of a two‐dimensional analytic model used to evaluate the energy exchange occurring as a train of electron microbunches traverses an active medium. Furthermore, advanced PASER concepts such as non‐linear interaction of electrons and waves in an active medium, the occurrence of resonant absorption instability, and PASER‐based optical Bragg accelerators, are considered as well. The possible impact of PASER‐based accelerators on future compact medical accelerators, and on high‐energy physics applications is discussed.
Ten‐year rate of longitudinal change in neurocognitive and motor function in prediagnosis Huntington disease
Authors: Solomon Andrea C. , Stout Julie C. , Weaver Marjorie , Queller Sarah , Tomusk Allison , Whitlock Kathryn Burr , Hui Siu L. , Marshall Jeanine , Jackson Jacqueline Gray , Siemers Eric R. , Beristain Xabier , Wojcieszek Joanne , Foroud Tatiana 
Published: September 2008

AbstractLongitudinal studies of neurocognitive function in prediagnosis Huntington disease (pre‐HD) have been few, and duration of follow‐up has been brief. In this study, 155 individuals at‐risk for HD completed a battery of cognitive and motor tasks at two study visits ∼10 years apart. Participants were classified as: (1) at‐risk, without the CAG expansion (healthy controls, NC; n = 112), or (2) CAG expanded (CAG+; n = 43). To examine the rate of decline at different stages of the pre‐HD period, participants in the CAG+ group were further characterized as converters (i.e., individuals who developed manifest HD over the course of the study; n = 21) or nonconverters (n = 22), and their performances were compared. The CAG+ group exhibited faster rates of neurocognitive decline over the course of the study, relative to the NC group. In addition, more rapid decline was associated with closer proximity to estimated age of disease onset in the CAG+ group. Faster rates of motor and psychomotor decline were observed in the CAG+ converter group, relative to the nonconverters. These findings suggest that neurocognitive decline in pre‐HD, particularly in motor and psychomotor domains, begins insidiously and accelerates as individuals approach disease onset. © 2008 Movement Disorder Society