bluuebunny/crossref_metadata_2025 huggingface dataset:
Methylenetetrahydrofolate reductase polymorphisms and risk of squamous cell carcinoma of the head and neck: A case‐control analysis
Authors: Neumann Ana S. , Lyons Heather J. , Shen Hongbing , Liu Zhensheng , Shi Qiuling , Sturgis Erich M. , Shete Sanjay , Spitz Margaret R. , El‐Naggar Adel , Hong Waun Ki , Wei Qingyi
Published: February 2005

Folate deficiency is implicated in cancer risk that may be modulated by a genetic variation in the methylenetetrahydrofolate reductase (MTHFR) gene in folate metabolism. We hypothesized that genetic variants in MTHFR are associated with risk of squamous cell carcinoma of the head and neck (SCCHN). We genotyped 3 MTHFR polymorphisms (C677T, A1298C and G1793A) and estimated their haplotypes in a hospital‐based case‐control study of 537 SCCHN cases and 545 cancer‐free controls. The controls were frequency‐matched to the cases by age (± 5 years), sex, ethnicity and smoking status. We found that the MTHFR 1298AC/CC genotypes were associated with an approximately 35% reduction in risk of SCCHN (adjusted odds ratio = 0.65; 95% CI = 0.51–0.82) compared to the AA genotype. The MTHFR 677CT and 1793GA/AA genotypes were associated with nonsignificant increased risk of SCCHN compared to the 677CC and 1793GG genotypes, respectively. We estimated that there were 8 haplotypes and 16 haplotype genotypes based on these 3 variants. When we used the haplotypes and assumed that the 677T, 1298A and 1793A alleles were risk alleles, the adjusted odds ratios increased as the number of risk alleles increased: 1.00 for 0–1 variant, 1.85 (1.3–2.5) for any 2 risk alleles and 1.93 (1.4–2.7) for any 3 risk alleles. These results suggest that all 3 MTHFR polymorphisms may play a role in the susceptibility to SCCHN among non‐Hispanic whites. Future studies should incorporate detailed data on alcohol consumption, dietary folate intake and related serologic measurements. © 2005 Wiley‐Liss, Inc.
Chemical structures from the analysis of domain‐averaged fermi holes. Nature of the MnMn bond in bis(pentacarbonylmanganese)
Authors: Ponec Robert , Yuzhakov Gleb , Sundberg Markku R.
Published: February 2005

Because of conflicting and contradictory classification based on traditional AIM characteristics, the nature of the MnMn bond has been and still is the subject of continuing discussions. To overcome the existing inconsistencies in the interpretation of the nature of this bond, the bonding in Mn2(CO)10 has been analyzed and discussed in terms of new recently proposed methodology known as the analysis of domain‐averaged Fermi holes. It has been shown that this analysis is able to reconcile the conflicting conclusions of earlier AIM‐based studies with traditional anticipations based on simple electron counting rules. According to Fermi hole analysis, the MnMn bond has the character of the more or less ordinary covalent single σ bond, but the analysis also brings clear evidence in favor of Mn · · · (CO) intramolecular interactions between the metal atom and the ligands bonded to the other metal atom. These interactions could be responsible for the observed decrease of electron density at the bond critical point detected in AIM studies. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 447–454, 2005
Short‐time Fourier transform analysis of ab initio molecular dynamics simulation: Collision reaction between CN and C4H6
Authors: Tamaoki Mari , Yamauchi Yusuke , Nakai Hiromi
Published: February 2005

Collision reactions between cyano radical (CN) and dimethylacetylene (C4H6) are thought to occur in the atmosphere of Saturn's moon Titan. However, it is difficult to reproduce reactions occurring in unique environments to study their dynamical processes. In this study, collision reactions between CN and C4H6 were investigated using ab initio molecular dynamics (AIMD) simulations. The simulation results were categorized into three kinds: nonreactive collision, incorporation, and substitution. Short‐time Fourier transform analysis of velocity autocorrelation functions obtained by the AIMD simulations, which has been recently developed by our research group, was performed to examine the nonequilibrium condition of the vibrational states. Spectrograms, which correspond to the time evolution of power spectra, clarify the relationship between the three reaction channels and the dynamical changes of the vibrational states. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 436–442, 2005
Heteroassociation of meso-sulfonatophenylporphyrins with β- and γ-cyclodextrin
Authors: EL-HACHEMI ZOUBIR , FARRERA JOAN-ANTON , GARCÍA-ORTEGA HECTOR , RAMÍREZ-GUTÍERREZ OSCAR , RIBÓ JOSEP M.
Published: January 2005

The effect of the addition of β- and γ-cyclodextrin (β-CD, γ-CD) to water solutions ( D 2 O ) of the 4'-sulfonato derivatives of meso-tetraphenylporphyrin (TPPS4, TPPS3, TPPS2o and TPPS2a) was studied by 1 H NMR at several temperatures. In all cases the disaggregation of the porphyrin homoassociates was detected, although in most cases it was only partial. Nuclear Overhauser signals (ROESY) show that cyclodextrin inclusion complexes were formed with TPPS4, TPPS3, and TPPS2o, but not with TPPS2a. These complexes include the sulfonatophenyl groups as guest, but not the hydrophobic phenyl substituents. The geometry of the complexes corresponds to that in which the sulfonatophenyl substituent is introduced through the secondary face of β-CD and through the primary face of γ-CD. In the inclusion complexes the polar sulfonato group is inside the cyclodextrin cavity but near to the hydrophilic interface with the bulk water. This explains the absence of complexation in the case of cationic porphyrins such as 5,10,15,20-tetrakis(N-methylpyridin-4-yl)porphyrin (TMPyP), and the decrease in the solubility when the β-CD complex of 5,15-bis(4-sulfonatophenyl)porphyrin (DPPS2o) forms. Complexes of the cyclodextrins with porphyrin homoassociates were also detected. This indicates that the heteroassociation avoids the formation of staggered stacks of porphyrin homoassociates, but has less effect on the association through the hydrophobic region of the phenyl substituents. This last type of aggregation, which is not significantly affected by the addition of α-CD, explains why the hydrophobic phenyl substituents are not complexed by the cyclodextrins.
Electrochemical and in situ spectroelectrochemical behavior of 2,3,7,8,12,13,17,18-octakis(hexyl-thio) tetraazaporphyrin (H2OHTTAP) and [Zn(II)OHTTAP]
Authors: ZHOU YANXIU , WANG ZHENXING , WANG DAIKE , SUGIURA KENICHI , SAKATA YOSHITERU
Published: January 2005

The characterization of free base porphyrin 2,3,7,8,12,13,17,18-octakis(hexyl-thio) tetraazaporphyrin (H2OHTTAP) and its zinc(II) complexes [ Zn (II)OHTTAP] containing eight thioether groups at the β-pyrrole positions of the macrocycle was reported. Results obtained by cyclic voltammetry and differential pulse voltammetry indicated a five-electron reduction in five steps for each complex. They were oxidized in two single-electron-transfer steps to yield π-cation radicals and dications and reduced in three single-electron-transfer steps to yield π-anion radicals, dianions and trianions, respectively. The redox property of H2OHTTAP was unusual as compared to porphyrins (PPs) and phthalocyanines (Pcs). Each process was monitored by in situ thin-layer spectroelectrochemistry, which indicated that only the ligand was electroactive. The existence of the eight hexylthio groups was responsible for the intrastack interactions and enhanced intracolumnar and intercolumnar electron motions, resulting in improved conductivity.
Polyethyleneoxide-capped phthalocyanines: limiting phthalocyanine aggregation to dimer formation
Authors: DOMINGUEZ D. D. , SNOW A. W. , SHIRK J. S. , PONG R. G. S.
Published: January 2005

The synthesis and characterization of a soluble metal-free polyethyleneoxide-capped phthalocyanine and the corresponding lead compound are described. This phthalocyanine was designed to allow the formation of dimers but to inhibit formation of higher aggregates. The monomer/dimer equilibrium constant in chloroform solutions is 750 ± 20 l mol -1. No evidence for higher aggregates was found. The molecular extinction coefficient of the metal-free polyethyleneoxide-capped phthalocyanine in chloroform is one of the lowest known (2.5 × 104 l mol -1 cm -1). The lead-substituted material was demonstrated to be a reverse saturable absorber from 532 nm to about 610 nm. It possesses a large nonlinear absorption coefficient in the visible and is a promising optical limiter material.
Influence of age after pruning on the levels of flavanols and other bioconstituents in tea (Camellia sinensis)
Authors: Thomas Jibu , Saravanan Marimuthu , Raj Kumar Rajagopal , Pius Parekatil Kurian
Published: January 2005

The influence of age after pruning on the biochemical constituents such as catechin fractions, the key enzyme phenylalanine ammonia lyase (PAL) and other compounds which contribute to black tea quality as well as root carbohydrates was investigated. Analyses were done consecutively for 4 years after pruning. The concentration of total catechins was found to be highest in the ‘Cambod’ cultivar UPASI‐17, followed by UPASI‐3 and UPASI‐9 representing ‘Assam’ and ‘China’ jats respectively, under prevailing conditions. A concomitant increase in total catechin content was found up to 3 years followed by a decrease in the fourth year of the pruning cycle, irrespective of the cultivar. PAL, the precursor of catechin biosynthesis, also increased up to 3 years and showed a sharp decrease thereafter. On the other hand, the root carbohydrate reserve and the caffeine content of tea leaves increased steadily up to the fourth year. All the genotypes studied showed the same trend. However, variability in catechin contents was prominent in different clones. Copyright © 2005 Society of Chemical Industry
Cell wall phenolics of white and green asparagus
Authors: Rodríguez Rocío , Jaramillo Sara , Guillén Rafael , Jiménez Ana , Fernández‐Bolaños Juan , Heredia Antonia
Published: January 2005

Cinnamic acids influence physical and textural attributes of plant foods as they play an important role in lignification and cross‐linking of cell‐wall polymers. Several trans‐cinnamic acids have been detected in asparagus cell wall (CW), and, of these, amounts of ferulic acid (FA) and its dehydrodimers have been found to increase significantly during post‐harvest storage. The distribution of these compounds along the different sections of white and green spears, as well as their modifications during postharvest storage, has been investigated. It has been observed that the cell walls from the apical, middle and lower sections of the green spears contain equivalent amounts of FA derivatives (about 400 µg g−1 CW), while these compounds are mainly located in the middle (681 µg g−1 CW) and lower section (975 µg g−1 CW) of the white ones. During asparagus post‐harvest storage a general increase of FA monomers and dimers took place that affected every section of both green and white spears. Major changes occurred in the middle and lower sections of the white asparagus, where the amounts of ferulic derivatives increased to 1700 and 1678 µg g−1 CW after storage. A similar but less pronounced trend was observed for the green spears. Copyright © 2005 Society of Chemical Industry
Fruit load or fruit position alters response to temperature and subsequently cherry tomato quality
Authors: Gautier Hélène , Rocci Aline , Buret Michel , Grasselly Dominique , Causse Mathilde
Published: January 2005

Changes in fruit–source ratio during the growth and maturation of cherry tomato fruits were studied in combination with increased fruit temperature. Six treatments were compared: the presence or absence of local heating combined with different fruit origins (7P, fruit from trusses pruned to seven flowers; 14P, proximal fruits; 14D, distal fruits from trusses pruned to 14 flowers). 7P were less sensitive to heating whereas 14P and 14D showed greater reduction in water and dry matter (DM) content. Distal fruits had the lowest structural DM (sDM), which could be due to a lower fruit cell number. Heating further decreased the sDM, so that fruit sink size was the lowest for distal fruits subjected to heating. Under low competition (7P), heating had a beneficial effect on sugar and lycopene content, whereas acids, β‐carotene and vitamin C content were reduced. Under high competition (14P, 14D), heating increased the ratio sDM–DM. This was mainly due to the reduced content of sugars and acids, but also to the reduced accumulation of secondary metabolites such as vitamin C, β‐carotene and lycopene. This study underlines the interactions between fruit temperature and the fruit–source ratio and the consequences for fruit composition and nutritional quality. Copyright © 2005 Society of Chemical Industry
Effect of hot air treatments on senescence and quality parameters of harvested broccoli (Brassica oleracea L var Italica) heads
Authors: Costa María L , Civello Pedro M , Chaves Alicia R , Martínez Gustavo A
Published: February 2005

Treatments with hot air were applied to broccoli (Brassica oleracea L) florets to investigate the effect on several quality and senescence parameters. To select the optimum treatment, florets were treated with different combinations of time/temperature ranging from 1 to 3 h and 37 to 50 °C and then placed in darkness at 20 °C. Most treatments delayed yellowing and loss of chlorophylls, except those performed at 37 °C, which accelerated senescence. Treatment at 48 °C for 3 h caused the highest delay in chlorophyll loss and was chosen to analyse its effect on quality and senescence. Non‐treated florets showed yellowing and reduced their chlorophyll content during storage. Heat treatment delayed the onset of chlorophyll catabolism by 1 day and slowed down the rate of degradation. Treated florets also showed lower losses of total sugars and proteins and an inhibition of protein solubilisation. Control heads showed an increment in CO2 production, which was not detected in heat‐treated florets. Total antioxidants decreased and thiobarbituric acid‐reactive substances (TBARS) increased during storage. The treatment delayed the decrease in antioxidant content and inhibited the increment in TBARS. In conclusion, treatment at 48 °C for 3 h delayed broccoli senescence at 20 °C and contributed to maintaining an overall better quality of the product. Copyright © 2005 Society of Chemical Industry
Improvement in intestinal function and health by the peel fibre derived from Citrus sinensis L cv Liucheng
Authors: Chau Chi‐Fai , Sheu Fuu , Huang Ya‐Ling , Su Li‐Hung
Published: February 2005

The water‐insoluble fibre‐rich fraction (WIFF) was isolated from the peel of Citrus sinensis L cv Liucheng in an economical way. The influences of a WIFF‐containing diet on the intestinal function and health in hamsters were investigated and compared with those of cellulose‐added and fibre‐free diets. Our results showed that the inclusion of WIFF in a fibre‐free diet might result in some significant improvements in serum, intestinal, caecal and faecal parameters, such as elevated serum alkaline phosphatase activity (127%), increased intestinal maltase and sucrase activities (180 and 164% respectively), decreased caecal pH (6.30), reduced caecal and faecal ammonia contents (by 25.4 and 34.1% respectively) and decreased activities of faecal β‐D‐glucosidase (by 48.1%), β‐D‐glucuronidase (by 52.9%) and urease (by 81.5%). These results suggested that the incorporation of WIFF in the diet at a level of 50 g kg−1 might exert a favourable effect on intestinal function and health. Accordingly, WIFF could be exploited as a potential functional ingredient in human diets and also offer industries an opportunity to develop new formulations of fibre‐rich functional foods. Copyright © 2005 Society of Chemical Industry
Selected properties of native or modified maize starch/soy protein mixtures extruded at varying screw speed
Authors: Seker Mahmut
Published: February 2005

Mixtures of soy protein isolate and native or modified (crosslinked) maize starch were extruded in a twin‐screw extruder at screw speeds of 80, 120 and 160 rpm and a moisture content of 250 g kg−1 (dry basis). Increasing screw speed did not affect the specific mechanical energy and water solubility and absorption indices but did affect the sectional expansion index and bulk density, as the flow rate of the feed was not held constant during extrusion. The sectional expansion indices of modified starch/soy protein mixtures were higher than those of native starch/soy protein mixtures, suggesting an effect of feed material in addition to phase transition on the expansion of extrudates containing soybean. Since the bulk densities of modified starch/soy protein mixtures were lower than those of native starch/soy protein mixtures, it appears that bulk densities of extrudates containing high percentages of soy protein can be reduced by the presence of crosslinked starch in the feed. Copyright © 2005 Society of Chemical Industry
An explanation for the combined effect of xylanase–glucose oxidase in dough systems
Authors: Primo‐Martín Cristina , Wang Mingwei , Lichtendonk Wim J , Plijter Johan J , Hamer Robert J
Published: February 2005

In the bakery industry, glucose oxidase is usually used in combination with xylanase. Although many theories exist on the mechanism of action of each enzyme, the positive effect of combining the two is as yet unexplained. In this paper we studied a possible basis for this synergy by focusing on the involvement of arabinoxylans. Water‐extractable arabinoxylans and water‐unextractable solids were studied in dough with or without glucose oxidase. Addition of glucose oxidase led to a stiffer and less extensible dough. Addition of arabinoxylans caused a further decrease in dough extensibility. Addition of xylanase could correct for this decrease. The role of arabinoxylans was further investigated by studying modified water‐extractable arabinoxylans and the effect of agents affecting arabinoxylan crosslinking (ferulic acid). Water‐extractable arabinoxylan was modified with xylanase to generate a low‐molecular‐weight fraction (WEAXXYL). Alternatively, it was modified with NaOH to prepare a fraction with a decreased ferulic acid content (WEAXOH). Addition of modified arabinoxylans diminished the effect of glucose oxidase. Glutenin macropolymer and water‐extractable arabinoxylan viscosity experiments were performed to obtain further detail on the role of arabinoxylans (AX). These results give rise to a new theory explaining the contribution of xylanase in its synergy with glucose oxidase. In this theory glucose oxidase not only catalyses the formation of protein disulfide bonds, but also of AX‐AX crosslinks. The latter negatively affect bread quality. Xylanase corrects for this latter effect by cleaving arabinoxylan complexes and generating small ferulic acid‐containing arabinoxylan fragments interfering with the crosslinking of high‐molecular weight arabinoxylans. Copyright © 2005 Society of Chemical Industry
Water shortage, deforestation and development: South Africa's working for water programme
Authors: Binns J. A. , Illgner P. M. , Nel E. L.
Published: January 2005

In the post‐apartheid era, South Africa is experiencing a serious water supply crisis as demand increases from both rural areas and rapidly growing towns and cities. New dams and water transfer schemes are being constructed, but they are both controversial and unlikely to fully satisfy demand. Alien species of trees and plants have invaded many parts of the country, taking over land from indigenous species. These alien species consume much more water than the indigenous vegetation, as well as threatening biodiversity and constituting a significant fire hazard. The Working for Water Programme, established in 1995, and working in partnership with local communities, aims to clear invasive alien species and thus increase water supply. The programme is examined in terms of its impact on environment and the livelihoods of predominantly poor rural communities. Questions are raised about the future sustainability of the programme. Copyright © 2001 John Wiley & Sons, Ltd.
The impact of privatization and regulation on the water and sewerage industry in England and Wales: a translog cost function model
Authors: Saal David S , Parker David
Published: January 2005

After the ten Regional Water Authorities (RWAs) of England and Wales were privatized in November 1989, the successor Water and Sewerage Companies (WASCs) faced a new regulatory regime that was designed to promote economic efficiency while simultaneously improving drinking water and environmental quality. As legally mandated quality improvements necessitated a costly capital investment programme, the industry's economic regulator, the Office of Water Services (Ofwat), implemented a retail price index (RPI)+Kpricing system, which was designed to compensate the WASCs for their capital investment programme while also encouraging gains in economic efficiency. In order to analyse jointly the impact of privatization, as well as the impact of increasingly stringent economic and environmental regulation on the WASCs' economic performance, this paper estimates a translog multiple output cost function model for the period 1985–1999. Given the significant costs associated with water quality improvements, the model is augmented to include the impact of drinking water quality and environmental quality on total costs. The model is then employed to determine the extent of scale and scope economies in the water and sewerage industry, as well as the impact of privatization and economic regulation on economic efficiency. Copyright © 2000 John Wiley & Sons, Ltd.
Government intervention in the economy: a comparative analysis of Singapore and Hong Kong
Authors: Lam Newman M. K.
Published: January 2005

Singapore and Hong Kong are very different and yet very similar in many respects. A study of their current profiles and historical development indicates that the two have achieved comparable economic successes through different development strategies. After World War II, Singapore gained political independence while Hong Kong achieved economic restructuring. The Singapore government adopted an interventionist approach to develop its economy, while the Hong Kong government followed the laissez‐faire principle. However, as the two were maturing socially and economically in the last few decades, both governments found the necessity to adopt a hybrid strategy of mixing economic interventions with the free‐market approach. An examination of public finance and economic policies since the onset of the Asian economic turmoil shows that the two have become increasingly similar in their economic approaches, with heavy emphasis on stabilizing the economy and stimulating business activities through government initiatives. Based on their projected economic, social and political development, the Hong Kong government is expected to become more interventionist while its Singapore counterpart is expected to go in the opposite direction. The economic development strategies of the two governments, coming from two extremes, will become more alike in the foreseeable future, for reasons of political feasibility in the former. Copyright © 2000 John Wiley & Sons, Ltd.
A comment on the limitations of the logical framework method, in reply to Gasper, and to Bell
Authors: Smith Peter
Published: January 2005

The note examines three inherent weaknesses of the logical framework (LF) approach. (i) It is based on binary logic, which biasses its output towards designs which are too complex and wide in scope, because that logic excludes the sort of approximate reasoning which would support practical compromises in design. (ii) Fuzzy logic is identified as a partial solution to this problem, but this introduces the issue of the naïve realism implicit in LF, which normally assumes that there is only one way of interpreting individual development problems. (iii) The paradigm underpinning LF is examined, and its implications for managing unexpected effects during implementation are drawn out. Copyright © 2000 John Wiley & Sons, Ltd.
The genetics of diabetes: a progress report
Authors: Gloyn Anna L.
Published: January 2005

Inheritance plays an important role in the cause of diabetes. A considerable amount of research is devoted to defining the genes involved in the aetiology of this widespread disease. This information is crucial if we are to improve our methods of preventing and treating diabetes. Over the last 25 years there have been considerable advances in our understanding of the genetics of both type 1 (insulin‐dependent) and type 2 (non‐insulin dependent) diabetes. Important discoveries have been made in dissecting the genes involved in a rare monogenic form of type 2 diabetes, which has become a paradigm for genetic studies of type 2 diabetes. Copyright © 2001 John Wiley & Sons, Ltd.
Chiral recognition in phosphinic acid dimers
Authors: Picazo Óscar , Alkorta Ibon , Elguero Jose , Mó Otilia , Yáñez Manuel
Published: February 2005

A theoretical study of chiral recognition in the minimum and proton transfer transition state structures of 15 pairs of chiral phosphinic acid dimers was carried out using DFT and MP2 methods, up to the MP2/6–311++G(3df,2p) level. The proton transfer proceeds via a concerted pathway in all cases studied. Even though these complexes show high interaction energies, of the order of 120 kJ mol−1, and short interatomic HB distances, our results show small energy differences between the homochiral (RR or SS) and the heterochiral dimers (RS or SR) both in the equilibrium configuration and in the proton transfer transition state owing to the disposition of the nonoxygen substituents of the phosphorus atom as proved with additional model complexes. Copyright © 2005 John Wiley & Sons, Ltd.
A novel strategy for the identification of toxinlike structures in spider venom
Authors: Kozlov Sergey , Malyavka Anton , McCutchen Bill , Lu Albert , Schepers Eric , Herrmann Rafi , Grishin Eugene
Published: February 2005

We compared two different approaches to sequence information analysis from the expressed sequence tag (EST) library constructed for the venom glands of the spider Agelena orientalis. Some results were more illustrative and reliable by the contig analysis technique, whereas our novel method, with specific structural markers introduced for protein structure detection, allowed us to overcome some limitations of the contig analysis. A novel technique was suggested for the identification in data banks of the spider's ion channel inhibitor toxins using primary structure features common to all spiders. Analysis of about 150 polypeptides made it possible to introduce 3 primary structure motifs for spider toxins: the Principal Structural Motif (PSM), which postulates the existence of 6 amino acid residues between the first and second cysteine residue and the Cys‐Cys sequence at a distance of 5–10 amino acid residues from the second cysteine; the Extra Structural Motif (ESM), which postulates the existence of a pair of CXC fragments in the C‐region; and the Processing Quadruplet Motif (PQM), which specifies the Arg residue at position −1 and Glu residues at positions −2, −3, and/or −4 in the precursor sequences just before the postprocessing site. In the processed data bank we found 48 toxinlike structures with ion channel inhibitor motifs. These include agelenin earlier isolated from Agelena opulenta and 25 more homologous sequences, 15 homologs of μ‐agatoxin 2 from the spider Agelenopsis aperta, 3 structures with low homology to ω‐agatoxin‐IIIA, and 4 new structures. Also we showed that toxinlike structures exceed two thirds of the overall database sequences. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Developmental changes in glutathione S‐transferase activity in herbicide‐resistant populations of Alopecurus myosuroides Huds (black‐grass) in the field
Authors: Milner Lucy J , Reade John P H , Cobb Andrew H
Published: January 2005

Herbicide‐resistant populations of Alopecurus myosuroides Huds (black‐grass) have become widespread throughout the UK since the early 1980s. Clear evidence suggests that more than one resistance mechanism exists, and glutathione S‐transferases (GSTs) have been implicated in resistance due to enhanced metabolism. This study reports the determination of GST activity in four UK black‐grass populations from field sites situated in the East Midlands. Data demonstrate that, as untreated plants in the field mature, there is an accompanying natural elevation of GST activity with natural environmental changes from winter to spring. We speculate that this endogenous change in enzyme activity with plant development in the field contributes to reduced efficacy of some graminicides applied in the spring. These observations are discussed in relation to predicting herbicide efficacy to achieve maximum control of this important grass weed.

© 2001 Society of Chemical Industry
Insights into peptide and protein function: a convergent approach12
Authors: Roques Bernard P.
Published: January 2005

From viruses to multicellular organisms, life is inseparable from the genetic instructions aimed at regulating its maintenance, division, multiplication, differentiation and death (apoptosis). Over the past 15 years, structural studies have begun to resolve the complex reactions involved in these fundamental processes in biology. The three‐dimensional representations of the complexes formed with peptides and/or proteins have allowed interpretation of the biochemical data and formulation of novel hypotheses about the control and execution of these processes. Moreover, they have opened the way to rational approaches for designing compounds able to interfere with these crucial events in normal or pathological conditions. Various results obtained in our laboratory in these fields are briefly summarized in this review. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd.
Luminescence properties of isolated InGaN/GaN quantum dots
Authors: Martin R. W. , Edwards P. R. , Taylor R. A. , Rice J. H. , Na J. H. , Robinson J. W. , Smith J. D. , Liu C. , Watson I. M.
Published: February 2005

InxGa1–xN quantum dots have been fabricated by the selective growth of GaN micro‐pyramid arrays topped with InGaN/GaN quantum wells. The spatially‐ and spectrally‐resolved luminescence properties of these structures were measured using low‐temperature micro‐photoluminescence spectroscopy. The presence of InGaN quantum dots was confirmed directly by the observation of sharp peaks in the emission spectrum at the pyramid apices. These luminescence peaks exhibit linewidths down to 650 µeV (limited by the spectrometer resolution). We describe the broadening of the luminescence peak from a single dot as a function of temperature and excitation power. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical spin polarization in double charged InAs self‐assembled quantum dots
Authors: Kalevich V. K. , Merkulov I. A. , Shiryaev A. Yu. , Kavokin K. V. , Ikezawa M. , Okuno T. , Brunkov P. N. , Zhukov A. E. , Ustinov V. M. , Masumoto Y.
Published: February 2005

The work is an experimental study of optical spin polarization in InAs/GaAs quantum dots (QDs) with 2 resident electrons or holes. A capture of a photo‐generated electron‐hole pair into such a QD creates a negative or positive tetron (double‐charged exciton). Spin polarization was registered by the circular polarization of the QD photoluminescence (PL). The spin state was found to differ radically in the dots with opposite in sign charge. Particularly, under excitation in a GaAs barrier, the ground state PL polarization is negative (relative to the polarization of an exciting light) in the negatively charged QDs and positive in the positively charged QDs. With increasing excitation intensity, the negative polarization rises from zero up to a saturation level, while the positive polarization decreases. The negative polarization increases in weak magnetic fields applied in Faraday geometry, but strong fields suppress it. The positive polarization always increases as a function of magnetic field. We propose a theoretical model that qualitatively explains the experimental results. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaN/AlGaN nanocavities with AlN/GaN Bragg reflectors grown in AlGaN nanocolumns by plasma assisted MBE
Authors: Ristić J. , Calleja E. , Fernández‐Garrido S. , Trampert A. , Jahn U. , Ploog K. H. , Povoloskyi M. , Carlo A. Di
Published: February 2005

The successful growth of AlGaN nanocolumns by plasma assisted MBE, with different Al compositions, opened the way for achieving nano‐heterostructures including GaN Quantum Discs (QDss). The luminescence emission from the QDss embedded in the AlGaN nanocolumns was tuned by changing their thickness and/or the Al composition of the barriers. Such a nano‐heterostructure was then enclosed between two AlN/GaN Distributed Bragg Reflectors (DBR), with nominal reflectivities of 90 and 50%. The choice of the AlN/GaN bilayers for the DBRs allowed to reach these reflectivity values with a significantly lower number of periods, as compared to the AlGaN/GaN stacks. The resulting nanocavity has been characterized by cathodoluminescence (CL), and Scanning and Transmission Electron Microscopy (SEM, TEM). CL measurements show that the emission from the nanocavity is quite close to the targeted value. TEM data points to the need of optimized conditions to grow AlN columnar layers in order to avoid the lateral overgrowth in the columnar nanostructure. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of B3LYP and MP2 conformational population distributions in trans‐nicotine, acetylcholine, and ABT‐594
Authors: Mora M. , Castro M. E. , Niño A. , Melendez F. J. , Muñoz‐Caro C.
Published: February 2005

This work presents an analysis of the equivalence of MP2 and DFT (B3LYP functional) conformational populations. As a test case, we select three cholinergic agents (trans‐nicotine, acetylcholine, and the nicotinic analgesic ABT‐594), where the minima on the conformational energy hypersurfaces expand a large range of energies (∼0–30 kJ mol−1). From energetic and structural data obtained in vacuo at the MP2 and B3LYP/cc‐pVDZ levels, we build conformational partition functions, including the effect of the conformational kinetic energy and the rotovibrational coupling. Our results at a physiological temperature (37°C) show qualitative agreement in all cases. Quantitative agreement, however, is only found for trans‐nicotine and ABT‐594. In the first case, energy minima differ by <0.2 kJ mol−1. Therefore, the equivalence of structural results translates in the equivalence of the conformational distribution. For ABT‐594, the minima are separated by as much as 8.0 kJ mol−1, and the conformational energy determines the conformational distribution. In this case, the slight relative variation of conformational energy, between B3LYP and MP2, does not affect the population, since the secondary minima are high in energy and very low in population. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Direct Observation of the Growth Process of MgO Nanoflowers by a Simple Chemical Route
Authors: Fang Xiao‐Sheng , Ye Chang‐Hui , Zhang Li‐De , Zhang Jun‐Xi , Zhao Jian‐Wei , Yan Peng
Published: February 2005

Novel flowerlike nanostructures consisting of MgO nanofibers were successfully synthesized by a simple chemical route with H2O at 950 °C in an Ar atmosphere. Various durations of heating gave different growth stages that led to varied product morphologies. The synthesized products were systematically studied by X‐ray powder diffraction, scanning electron microscopy, high‐resolution transmission electron microscopy, and energy‐dispersive X‐ray analysis. The results show that the nucleation and growth process of the nanoflowers seems to be a vapor–solid mechanism, and that the total heating time during the reaction process is a critical factor for the development of MgO nanoflowers. Initially, Mg particles formed on the Si substrate, followed by the formation of MgO clusters as nucleation centers on the magnesium melt surface and the nucleation of short MgO nanofibers, then growth of the MgO nanofibers occurred, and finally MgO nanoflowers were formed. Besides nanoflowers, novel hierarchical MgO nanostructures were also observed. These nanostructures may be used as three‐dimensional composite materials and as supports for other materials.
Modelling fault‐proneness statistically over a sequence of releases: a case study
Authors: Ohlsson Magnus C. , Andrews Anneliese Amschler , Wohlin Claes
Published: January 2005

Many of today's software systems evolve through a series of releases that add new functionality and features, in addition to the results of corrective maintenance. As the systems evolve over time it is necessary to keep track of and manage their problematic components. Our focus is to track system evolution and to react before the systems become difficult to maintain. To do the tracking, we use a method based on a selection of statistical techniques. In the case study we report here that had historical data available primarily on corrective maintenance, we apply the method to four releases of a system consisting of 130 components. In each release, components are classified as fault‐prone if the number of defect reports written against them are above a certain threshold. The outcome from the case study shows stabilizing principal components over the releases, and classification trees with lower thresholds in their decision nodes. Also, the variables used in the classification trees' decision nodes are related to changes in the same files. The discriminant functions use more variables than the classification trees and are more difficult to interpret. Box plots highlight the findings from the other analyses. The results show that for a context of corrective maintenance, principal components analysis together with classification trees are good descriptors for tracking software evolution. Copyright © 2001 John Wiley & Sons, Ltd.
Performance evaluation of distributed‐antenna communications systems using beam‐hopping
Authors: Hu Honglin , Zhu Jinkang , Yang Lie‐Liang
Published: February 2005

Digital beamforming (DBF) techniques are capable of improving the performance of communications systems significantly. However, if the transmitted signals are conflicted with strong interference especially in the direction of the transmitted beams, these directional jamming signals will severely degrade the system performance. In order to efficiently mitigate the interference of the directional jammers, in this contribution a beam‐hopping (BH) communications scheme is studied. In the BH communications scheme, only one pair of the beams is used for transmission and it hops from one to the next according to an assigned BH pattern. In this contribution, a range of expressions in terms of the average signal to interference plus noise ratio (SINR) performance have been derived, when both the uplink and downlink are considered. The average SINR performance of the BH scheme and that of the conventional single‐beam (SB) as well as multiple‐beam (MB) assisted beam‐processing schemes have been investigated. Our analysis and results show that the BH scheme is capable of efficiently combating the directional jamming, with the aid of utilizing the directional gain of the beams generated by both the transmitter and the receiver. Furthermore, the BH scheme is capable of reducing the intercept probability of the communications. Therefore, the BH scheme is suitable for communications when several distributed antenna arrays are available around a mobile. Copyright © 2005 John Wiley & Sons, Ltd.
Analysis and optimization of pilot‐symbol‐assisted M‐QAM for OFDM systems
Authors: Chen Jiming , Tang Youxi , Li Shaoqian
Published: February 2005

Orthogonal frequency division multiplexing (OFDM) is very attractive for next generation high‐speed wireless communication because of its various advantages in lessening the severe effects of frequency‐selective fading. When using pilot symbol assisted (PSA) M‐ary quadrature amplitude modulation (M‐QAM) in OFDM systems, if the power of pilot is too low, the channel parameters cannot be accurately estimated, whereas, high pilot power will lead to less power left for data symbols under the condition that the total transmitted power is constrained to be a constant. In this paper, we present how pilot power affects the demodulation performance in Rayleigh fading propagation environments. Consequently, the pilot‐to‐data power ratio (PDR) is optimized analytically, and degradation of system performance due to inaccurate channel estimation is also evaluated. The theoretical and simulation results show that the optimum PDR is affected by the signal‐to‐noise ratio (SNR), Doppler frequency and interpolation size etc. When the optimum PDR is adopted for an OFDM system, the total transmission power will be minimal for certain bit error rate (BER) target. Copyright © 2005 John Wiley & Sons, Ltd.
Family dynamics, gender differences and educational attainment in Filipino adolescents
Authors: Hindin Michelle J.
Published: February 2005

The relationship between parenting style, marital relationships and subsequent educational attainment is explored among 1428 Filipino adolescents attending school in 1994 and 1096 attending school in 1999. Girls in households where their fathers physically abused their mothers were significantly less likely to complete primary school, and girls who reported parental arguments completed fewer grades. In contrast, girls in households where parents made decisions jointly were more likely to finish secondary school and attain more grades. Boys attained more education if they reported being close to their mothers. Boys with authoritative mothers attained more grades and were more likely to complete secondary school as compared to boys with neglectful mothers. In this context, marital relationships and parent–child relationships are important for understanding adolescent educational attainment.
Characterisation of a novel amylosucrase from Deinococcus radiodurans
Authors: Pizzut-Serin Sandra , Potocki-Véronèse Gabrielle , van der Veen Bart A. , Albenne Cécile , Monsan Pierre , Remaud-Simeon Magali
Published: February 2005

The BLAST search for amylosucrases has yielded several gene sequences of putative amylosucrases, however, with various questionable annotations. The putative encoded proteins share 32–48% identity with Neisseria polysaccharea amylosucrase (AS) and contain several amino acid residues proposed to be involved in AS specificity. First, the B‐domains of the putative proteins and AS are highly similar. In addition, they also reveal additional residues between putative β‐strand 7 and α‐helix 7 which could correspond to the AS B′‐domain, which turns the active site into a deep pocket. Finally, conserved Asp and Arg residues could form a salt bridge similar to that found in AS, which is responsible for the glucosyl unit transfer specificity. Among these found genes, locus NP_294657.1 (dras) identified in the Deinococcus radiodurans genome was initially annotated as an α‐amylase encoding gene. The putative encoded protein (DRAS) shares 42% identity with N. polysaccharea AS. To investigate the activity of this protein, gene NP_294657.1 was cloned and expressed in Escherichia coli. When acting on sucrose, the pure recombinant enzyme was shown to catalyse insoluble amylose polymer synthesis accompanied by side‐reactions (sucrose hydrolysis, sucrose isomer and soluble maltooligosaccharide formation). Kinetic analyses further showed that DRAS follows a non‐Michaelian behaviour toward sucrose substrate and is activated by glycogen, as is AS. This demonstrates that gene NP_294657.1 encodes an amylosucrase.
Serum/glucocorticoid‐inducible kinase can phosphorylate the cyclic AMP response element binding protein, CREB
Authors: David Samuel , Kalb Robert G.
Published: February 2005

To maintain homeostasis, cells often respond to stressful extra‐cellular stimuli by new gene expression. Serum/glucocorticoid‐induced kinase (SGK) is an immediate early gene whose expression is induced by a variety of extra‐cellular stimuli. Here, we examine the possibility that SGK can directly phosphorylate the transcription factor cyclic AMP response element binding protein (CREB). In a cell‐free context, SGK physically associates with CREB and SGK phosphorylates it on serine 133. Phospho‐serine 133 is essential for stimulating the transcriptional activity of CREB. Further, we show that in a variety of cellular contexts, SGK phosphorylates CREB. Activation of receptor tyrosine kinase pathways or the phosphoinositide‐dependent kinase 1 (PDK1) lead to SGK‐dependent CREB phosphorylation. Hormonal stimulation of epithelial cells leads to the induction of endogenous SGK and CREB phosphorylation. A dominant‐negative form of SGK blocks dexamethasone‐induced CREB phosphorylation. Our studies indicate that stimulation of SGK can lead to CREB phosphorylation, suggesting that CREB‐dependent gene transcription is an important link between stressful extra‐cellular signals and cellular responses.
Celecoxib and ketoprofen for pain management during tonsillectomy: A placebo‐controlled clinical trial
Authors: Nikanne Elina , Kokki Hannu , Salo Juha , Linna Timo‐Jussi
Published: February 2005

OBJECTIVE

To evaluate the efficacy and safety of celecoxib and ketoprofen in pain management during tonsillectomy in 120 patients.

STUDY DESIGN AND SETTING

The study was randomized, double‐blind, and placebo‐controlled with parallel groups. Sixty minutes before anesthesia induction and 12 hours after, the patients received a 200‐mg celecoxib, a 100‐mg ketoprofen, or a placebo capsule. After discharge, patients were prescribed either celecoxib or ketoprofen capsules to be taken every 12 hours.

RESULTS

During the first 24 hours, the need for rescue analgesic was less in the ketoprofen‐group (5 (1‐9)) doses (median (range)) than in the placebogroup (6 (1‐13)) (P = 0.021), but similar to the cele‐coxib‐group (5 (2‐14)). After discharge, the cessation of pain during eating occurred earlier in the celecoxib‐treated patients, after 10 (1‐17) days, than in the ketoprofen‐treated patients, after 12 (1‐21) days, (P = 0.008). One celecoxib‐treated patient and 6 ketoprofen‐treated patients (P = 0.013) needed electrocautery to stop postoperative bleeding.

CONCLUSION

Ketoprofen provided a better initial analgesic efficacy but after discharge the recovery with celecoxib was faster and the incidence of secondary hemorrhages was lower.

SIGNIFICANCE

Celecoxib seems to be more effective and safe than ketoprofen for pain management after discharge in patients with tonsillectomy.
Indications for the Caldwell‐Luc approach in the endoscopic era
Authors: Barzilai Geva , Greenberg Elhanan , Uri Nechama
Published: February 2005

OBJECTIVE

Caldwell and Luc described the Caldwell‐Luc operation more than 100 years ago as the surgical treatment for maxillary sinus disease. During the last decades less radical interventions using endoscopic approach have mainly replaced the classical procedures done for chronic and recurrent maxillary sinusitis.

STUDY DESIGN AND SETTING

Between 1991 and 2002, 62 patients had the Caldwell‐Luc approach for different indications.

RESULTS

Twenty (32%) patients had chronic sinusitis, 16 (26%) patients had inverted papilloma, 9 (15%) patients had suffered from nasal polyposis, 4 patients (6%) had dentigerous cyst, 4 (6%) patients had fungal ball, and 9 (15%) patients were operated for other indications.

CONCLUSIONS

The use of this surgical approach is rational in cases of fungal disease and in endoscopic medial maxillectomy for treating inverted papilloma. In all other cases, the preferred approach should now be endoscopic.
Simultaneous bilateral posterior cordectomy in bilateral vocal fold paralysis
Authors: Khalifa Mohamed Chafik
Published: February 2005

The operation of simultaneous bilateral posterior cordectomy by CO2 laser was performed in 22 cases of bilateral vocal fold paralysis. The success rate was up to 92% with good airway and voice quality. The procedure is simple, cost‐effective with virtually no complications. Problems related to deglutition, aspiration, or granuloma formation were not reported.