bluuebunny/crossref_metadata_2025 huggingface dataset:
IgA directed against early antigen of Epstein‐Barr virus is no specific marker for the diagnosis of nasopharyngeal carcinoma
Authors: Sigel Gottfried , Schillinger Monika , Henninger Klaus , Bauer Georg
Published: March 2007

The aim of this study was to evaluate the significance and specificity of IgA directed against Epstein‐Barr virus (EBV)‐specific early antigens (EA) for the unequivocal diagnosis of nasopharyngeal carcinoma (NPC). Therefore, sera from patients with diseases other than NPC, selected on the basis of elevated antibody titres against EBV antigens, were compared to sera from NPC patients with regard to the presence of IgA directed against EBV viral capsid antigen (VCA‐IgA) and IgA directed against EA (EA‐IgA). Four hundred forty‐seven out of 7,508 non‐NPC sera tested showed high titres (>512) of IgG directed against Epstein Barr viral capsid antigen (VCA‐IgG) and positive VCA‐lgA (⩾32). Two hundred twenty‐seven of these sera were compared to 51 VCA‐IgA‐positive sera from NPC patients regarding the titre of EA‐lgA. 60.7% of VCA‐lgA‐positive NPC sera showed positive EA‐lgA, however 33% of VCA‐IgA‐positive non‐NPC patients also exhibited EA‐lgA. This result demonstrates that EA‐lgA is not specific for NPC and does not allow an unequivocal serological diagnosis of NPC in individual cases. It seems therefore to be of questionable use for screening programs in NPC low‐risk areas. The data do not contradict the usefulness of this marker for monitoring of patients treated for NPC and for screening programmes in high‐risk areas. © 1994 Wiley‐Liss, Inc.
Detection of human papillomavirus using the polymerase chain reaction and typing for HPV16 and 18 in the cervical smears of Greek women
Authors: Lambropoulos A. F. , Agorastos T. , Frangoulides E. , Karahaliou R. , Bontis J. , Dozi‐Vassiliades I.
Published: March 2007

The polymerase chain reaction (PCR) was applied for the detection of human papilloma virus (HPV) infection, in samples obtained from the uterine cervices of 202 asymptomatic women with normal cytology in Northern Greece. About 41.8% of the women with microscopically and cytologically normal cervices were found to be infected with HPV. Typing of HPV revealed that 6.9% and 1.5% of the women were infected with HPV16 and HPV18, respectively. © 1994 Wiiey‐Liss, Inc.
Effect of postexposure vaccination in a chimpanzee model of hepatitis A virus infection
Authors: Robertson Betty H. , D'Hondt Eric H. , Spelbring John , Tian Houwen , Krawczynski K. , Margolis Harold S.
Published: March 2007

Passive transfer of antibodies to hepatitis A virus (HAV) in immune globulin (IG) effectively prevents hepatitis A when given after exposure, but does not provide lasting protection from infection. Hepatitis A vaccines have been shown to generate quickly levels of antibody equivalent to those found after IG administration. The effect of hepatitis A vaccine in preventing infection following fecal‐oral exposure was evaluated in a chimpanzee model of HAV infection. Two animals were vaccinated 1 and 3 days, respectively following inoculation and two inoculated animals served as unprotected controls. Of the two immunized animals, one had no evidence of HAV infection, while the other had an attenuated infection with no evidence of virus shedding. These results suggest that while postexposure hepatitis A vaccination may be infection permissive, it attenuates disease expression and prevents virus shedding. © 1994 Wiley‐Liss, Inc.
A nested case‐control study on association between hepatitis C virus antibodies and primary liver cancer in a cohort of 9,775 men in Taiwan
Authors: Chang Chao‐Chin , Yu Ming‐Whei , Lu Chih‐Feng , Yang Czau‐Siung , Chen Chien‐Jen
Published: March 2007

Most studies on the association between antibodies against hepatitis C virus (anti‐HCV) and primary liver cancer (PLC) were limited to case‐series, or cross‐sectional case‐control studies leaving a controversy on causal temporality. A nested case‐control study on 38 newly‐developed PLC patients and 152 matched controls selected from a cohort of 9,775 men in Taiwan recruited from September, 1984, to February, 1986, was carried out to examine the relation between HCV infection and PLC. Case‐control pairs were matched on age (±1 year), residence, and the date at recruitment. Serum samples collected from study subjects at the initial recruitment were examined for anti‐HCV by enzyme immunoassay and hepatitis B surface antigen (HBsAg) by reverse passive hemagglutination assay combined with radioimmunoassay. History of cigarette smoking, alcohol consumption, vegetable consumption, vegetarian habit, and chronic liver diseases were also obtained through standardized interviews according to a structured questionnaire at the recruitment. After adjusting for HBsAg status and other risk factors, the anti‐HCV was significantly associated with the development of PLC showing a multivariate‐adjusted relative risk of 88.24. The results suggest that HCV infection may play an important role in the etiology of human PLC in Taiwan. © 1994 Wiley‐Liss, Inc.
Quantitative analysis of wild‐type and HBeAg minus hepatitis B viruses by a sequence‐dependent primer extension assay
Authors: Brunetto M. R. , Randone A. , Ranki M. , Jalanko A. , Piantino P. , Giarin M. , Capra G. , Calvo P. L. , Oliveri F. , Bonino F.
Published: March 2007

The ratio between wild‐type hepatitis B virus (HBV) and HBV mutant, unable to secrete “e” antigen (HBeAg minus HBV) appears to be an important determinant of the outcome of chronic hepatitis B. Quantitative analysis of wild‐type and HBeAg minus HBVs in the blood could be useful to monitor chronic hepatitis B patients. We developed a solid‐phase minisequencing assay for both viruses using a primer‐guided incorporation of a single labeled nucleotide on an affinity captured biotinylated amplified HBV‐DNA template. A standard curve was constructed by mixing increasing quantities of wild type and mutant virus DNAs. The detection of wild‐type and HBeAg minus sequences, ranging from 10% to 90% of overall viremia, was linear and reproducible till 0.1 pg/μl of serum HBV‐DNA. The assay yields numerical values and the ratio of incorporated nucleotides defines the relative proportions (%) of the two viral sequences with accuracy. We tested the sensitivity and accuracy of the minisequencing on mixed end point dilutions of wild‐type and HBeAg minus reference sera and amplified products. The feasibility and reproducibility of the assay were tested in 35 sera from 21 HBsAg positive patients with chronic hepatitis B using both minisequencing and oligo‐hybridization assays. A high correlation was found between the two assays (r = 0.957 P < 0.0001). In conclusion, the minisequencing assay provides a precise and reproducible quantitative analysis of wild‐type and HBeAg minus HBVs in clinical specimens. It is proposed to study the relations between HBV heterogeneity and the course of hepatitis B and its response to therapy. © 1994 Wiley‐Liss, Inc.
Numerical simulations of confocal Raman spectroscopic depth profiles of materials: a photon scattering approach
Authors: Macdonald A. M. , Vaughan A. S.
Published: March 2007

We present a simple model that uses a novel photon scattering approach to predict the depth profile response obtained when confocal Raman spectroscopy is applied both to silicon and to a number of related polymeric materials of varying optical clarity. This paper first provides an overview of the models proposed to date to demonstrate the evolution in understanding of the confocal Raman response of semi‐transparent materials, based upon geometrical optics. A new model is then described that is based upon the twin notions of a permanent extended Raman illuminated volume and the degree of extinction of the incident and Raman scattered photons from the whole of the illuminated volume as it is gradually moved further into, or defocused above, the sample. The model's predictions are compared with empirical data from previous studies of a range of semi‐crystalline polymers with different scattering properties and, by means of contrast, with that of a silicon sample. We show that, despite its inherent simplicity, the physics this model utilizes is able successfully to predict the form of the depth profile for each material, something that has not been achieved by any model previously proposed, and that the parameters used in the model scale with independent physical measurements. Finally the model is used to account for the fact that useful Raman spectra can be obtained when the laser is focused as much as 40 µm above the sample surface. Copyright © 2007 John Wiley & Sons, Ltd.
The effect of the pore structure and zeta potential of porous polymer monoliths on separation performance in ion‐exchange mode
Authors: Liapis Athanasios I. , Grimes Brian A.
Published: March 2007

Most often, in bioseparations involving charged macromolecules, the chromatographic systems have low Reynolds and high Peclet numbers. For such systems, an expression is developed and presented in this work for evaluating the throughput in polymeric monoliths where ion‐exchange adsorption occurs, as a function of (i) the pressure drop along the length of the monolith, (ii) the functional form and width of the throughpore‐size distribution of the monolith, and (iii) the magnitude of the zeta potential on the surface of the throughpores of the monolith. Gaussian and log‐normal throughpore‐size distributions whose mean throughpore‐size and standard deviation values are based on experimentally measured throughpore‐size distribution data by mercury porosimetry employed on polymeric monoliths are used in this work, and their effect on the throughput relative to that obtained from a polymeric monolith having a uniform throughpore‐size distribution is studied for different values of the ratio of the standard deviation to the mean throughpore‐size. The results indicate that relatively modest increases in the throughput, when compared with the throughput that could be achieved in a polymeric monolith having a uniform throughpore‐size distribution, could be obtained in polymeric monoliths having disperse throughpore‐size distributions, and the magnitude of the increase becomes larger when the disperse distribution is skewed to larger throughpore sizes. Furthermore, the results of this work indicate that, under certain conditions, relatively modest increases in the throughput of a charged analyte could also be achieved by altering the value of the zeta potential on the surface of the throughpores of the monolith. Due to the difficulties inherent in controlling the functional form and width of the throughpore‐size distribution during the synthesis of polymeric monoliths, it would appear to be more practical to increase the value of the throughput of a charged analyte by altering the value of the zeta potential through prudent selection of the ion‐exchange surface functional groups and fine‐tuned with the pH of the mobile phase. Thus, for ion‐exchange chromatography systems, the zeta potential could be considered an important parameter for column designers and operators to manipulate, since its alteration could increase the throughput of a charged analyte in polymeric monoliths or in columns packed with charged particles.
Evaluation of the separation characteristics of application‐specific (fatty acid methyl esters) open‐tubular columns for gas chromatography
Authors: Kiridena Waruna , Qian Jing , Koziol Wladyslaw W. , Poole Colin F.
Published: March 2007

The solvation parameter model is used to characterize the separation properties of the polar stationary phases EC‐Wax and PAG with a poly(ethylene oxide) backbone (substituted with propylene oxide in the case of PAG) and the cyanopropyl‐substituted polysilphenylene–siloxane stationary phase BPX90 at five equally spaced temperatures between 60 and 140°C. The separation characteristics of these stationary phases are compared to four PEG and two poly(cyanopropylsiloxane) stationary phases (HP‐20M, HP‐Innowax, SolGel‐Wax, DB‐WAXetr, HP‐88, and SP‐2340) characterized in the same way. The database of system constants for these polar stationary phases is used to provide insight into the separation mechanism for fatty acid methyl esters and to determine selectivity differences that can be expected for generically similar stationary phase types. The discussion is not structured to indicate which stationary phase should be used for a particular separation but to provide a general framework to demonstrate the relationship between the retention mechanism and stationary phase chemistry.
Bio‐diesel lubricity: correlation study with residual acidity
Authors: Sarin Rakesh , Arora Ajay K. , Ranjan Rajeev , Gupta Anurag A. , Malhotra Ravinder K.
Published: March 2007

Bio‐diesel has been accepted as a renewable liquid biofuel worldwide. In order to ensure customers' acceptance, standardisation and quality assurance are the key factors to the market introduction of bio‐diesel as a transport fuel. Lubricity of bio‐diesel is an important issue and it is well reported that 1–2% bio‐diesel is sufficient to maintain the lubricity of diesel even of very poor lubricity.

However, a wide variation in lubricity performance of bio‐diesel from different vegetable oils and sources has been noticed. In addition, on critical examination, it was noticed that the variation in the lubricating performance of bio‐diesel could be better linked to its residual acidity than to variation in fatty acid composition. Copyright © 2007 John Wiley & Sons, Ltd.
Existence and some properties of weak solutions for a singular nonlinear parabolic equation
Authors: Qiang Liu , Zheng'an Yao , Wenshu Zhou
Published: March 2007

This paper deals with the initial and boundary value problem for a singular nonlinear parabolic equation. The existence of solutions is established by parabolic regularization. Some properties of solutions, for instance localization and large time behaviour are also discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Reporting practices of dropouts in psychological research using a wait‐list control: current state and suggestions for improvement
Authors: Cisler Josh M. , Barnes Aaron C. , Farnsworth Donald , Sifers Sarah K.
Published: March 2007

Reporting practices regarding dropouts in wait‐list control studies hold great importance for the ability to replicate, generalize, and draw conclusions from research. This concern is applicable to all psychological research utilizing wait‐list controls, regardless of purpose of research (e.g., treatment outcome). The current study assessed the present state of reporting practices in this type of experimental design and discussed the limitations and implications of the insufficient reporting found. 171 articles from psychology journals utilizing wait‐list control design were surveyed regarding the reporting of the number of dropouts from the wait‐list control and experimental conditions, characteristics and assessment scores of the dropouts, and total dropouts. Variables that are crucial to interpreting research findings are not consistently reported. Additionally, journal impact factor and year of publication were positively correlated with the adequacy of reporting. Consistencies with previous findings were noted, and suggestions for remedying the reporting inadequacies were discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Relaxation by clustered ferritin: a model for ferritin‐induced relaxation in vivo
Authors: Gossuin Yves , Gillis Pierre , Muller Robert N. , Hocq Aline
Published: March 2007

Ferritin, the iron‐storing protein of mammals, is known to darken T2‐weighted MR images. This darkening could be used for the non‐invasive measurement of an organ's iron content. Unexplained discrepancies exist between T2 data obtained in ferritin‐containing tissues and aqueous solutions of ferritin. The clustering of the protein induced by trypsin is used to evaluate the effect of ferritin agglomeration on the relaxation rates. Although the longitudinal relaxation is not significantly influenced by clustering, T2 depends greatly on the stage of agglomeration: the transverse relaxation rate is higher for a clustered sample than for an unclustered sample. Moreover, the field and inter‐echo time dependences of the relaxation rate indicate that the relaxation mechanism may be different between small clusters – where a linear dependence of 1/T2 on B0 is observed – and large clusters – where a quadratic dependence is observed. These results help to explain the relaxation induced by ferritin in tissues. Copyright © 2007 John Wiley & Sons, Ltd.
Feasibility of complementary spatial modulation of magnetization tagging in the rat heart after manganese injection
Authors: Hyacinthe J.‐N. , Ivancevic M. K. , Daire J.‐L. , Vallée J.‐P.
Published: March 2007

It has been shown that manganese‐enhanced MRI (MEMRI) can safely depict the myocardial area at risk in models of coronary occlusion–reperfusion for at least 2 h after reperfusion. To achieve this, a solution of MnCl2 is injected during coronary occlusion. In this model, the regional function quantification deficit of the stunning phase cannot be assessed before contrast injection using MR tagging. The relaxation effects of manganese (which remains in normal cardiac myocytes for several hours) may alter the tags by increasing tag fading and hence the quality of strain measurement. Therefore, we evaluated the feasibility of cardiac MR tagging after manganese injection in normal rats. Six normal Sprague–Dawley rats were imaged in vivo using complementary spatial modulation of magnetization (C‐SPAMM) at 1.5 T, before and 15 min after intraperitoneal injection of MnCl2 solution (∼17.5 µmol kg−1). The contrast‐to‐noise ratio of the tag pattern increased significantly (P < 0.001) after injection and remained comparable to the control scan in spite of the higher myocardial relaxation rate caused by the presence of manganese. The measurements of circumferential strain obtained from harmonic phase imaging analysis of the tagged images after MnCl2 injection did not differ significantly from the measurements before injection in the endocardial, mid‐wall, and epicardial regions. In particular, the transmural strain gradient was preserved. Thus, our study suggests that MR tagging could be used in combination with MEMRI to study the acute phase of coronary artery disease. Copyright © 2007 John Wiley & Sons, Ltd.
Relaxation WENO schemes for multidimensional hyperbolic systems of conservation laws
Authors: Banda Mapundi , Seaïd Mohammed
Published: March 2007

We present a class of high‐order weighted essentially nonoscillatory (WENO) reconstructions based on relaxation approximation of hyperbolic systems of conservation laws. The main advantage of combining the WENO schemes with relaxation approximation is the fact that the presented schemes avoid solution of the Riemann problems due to the relaxation approach and high‐resolution is obtained by applying the WENO approach. The emphasis is on a fifth‐order scheme and its performance for solving a wide class of systems of conservation laws. To show the effectiveness of these methods, we present numerical results for different test problems on multidimensional hyperbolic systems of conservation laws. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
Implicit–explicit multistep characteristic finite element methods for nonlinear convection–diffusion equations
Authors: Long Xiaohan , Chen Chuanjun
Published: March 2007

Implicit–explicit multistep characteristic methods are given for convection‐dominated diffusion equations. Multistep difference along characteristics of the one‐order hyperbolic part of the equation is used for discretization in time, and finite element method is used to discrete the space variables. The resulting schemes are consistent, stable and very efficient. Optimal‐rate of convergence is proved. Also, a note is given for a paper published earlier© 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2007
An Eulerian‐Lagrangian discontinuous Galerkin method for transient advection‐diffusion equations
Authors: Wang Kaixin , Wang Hong , Al‐Lawatia Mohamed
Published: March 2007

We develop an Eulerian‐Lagrangian discontinuous Galerkin method for time‐dependent advection‐diffusion equations. The derived scheme has combined advantages of Eulerian‐Lagrangian methods and discontinuous Galerkin methods. The scheme does not contain any undetermined problem‐dependent parameter. An optimal‐order error estimate and superconvergence estimate is derived. Numerical experiments are presented, which verify the theoretical estimates.© 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2007
Effect of numerical integration in the DGFEM for nonlinear convection‐diffusion problems
Authors: Sobotíková Veronika , Feistauer Miloslav
Published: March 2007

This paper is concerned with the effect of numerical integration applied to the discontinuous Galerkin finite element discretization of nonlinear convection‐diffusion problems in 2D. In the space semidiscretization the volume and line integrals are evaluated by numerical quadratures. Our goal is to estimate the error caused by the numerical integration and to show what numerical quadratures guarantee that the accuracy of the method with exact integration is preserved. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
Finite‐difference time‐domain simulation of acoustic propagation in heterogeneous dispersive medium
Authors: Norton Guy V.
Published: March 2007

Accurate modeling of pulse propagation and scattering is a problem in many disciplines (i.e., electromagnetics and acoustics). It is even more tenuous when the medium is dispersive. Blackstock [D. T. Blackstock, J Acoust Soc Am 77 (1985) 2050] first proposed a theory that resulted in adding an additional term (the derivative of the convolution between the causal time‐domain propagation factor and the acoustic pressure) that takes into account the dispersive nature of the medium. Thus deriving a modified wave equation applicable to either linear or nonlinear propagation. For the case of an acoustic wave propagating in a two‐dimensional heterogeneous dispersive medium, a finite‐difference time‐domain representation of the modified linear wave equation can been used to solve for the acoustic pressure. The method is applied to the case of scattering from and propagating through a 2‐D infinitely long cylinder with the properties of fat tissue encapsulating a cyst. It is found that ignoring the heterogeneity in the medium can lead to significant error in the propagated/scattered field. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
Spondylolysis in the lower thoracic–upper lumbar spine in a British medieval population
Authors: Mays S.
Published: March 2007

Spondylolysis is generally a condition of the lower lumbar spine, but occasionally it is observed at cranial to L4. It is generally agreed that spondylolysis in the lower lumbar spine represents fatigue failure of the neural arch. However, whether a biomechanical explanation is adequate to explain lesions cranial to L4 is disputed. Morphological aspects of spondylolysis at T12–L3 (five cases) are compared with those of lesions at L4–L6 (24 cases) in a mediaeval English skeletal series with the aim of shedding light upon any differences in aetiology of lesions at the two sites. It was found that spondylolysis at T12–L3 was more often unilateral than in L4–L6. In T12–L3, clefts more often took an angulated, dog‐leg course across the pars interarticularis, whereas most in L4–L6 were fairly straight and had an oblique orientation. In T12–L3, clefts often had facetted opposing surfaces suggestive of a diarthrodial joint, but this was only seen once in L4–L6. It is suggested on morphological grounds that facetted defects are more likely congenital than acquired. The need for consideration of factors in addition to activity regimes when interpreting spondylolysis in earlier populations is emphasised. Copyright © 2007 John Wiley & Sons, Ltd.
A two‐station embossing process for rapid fabrication of surface microstructures on thermoplastic polymers
Authors: Yao Donggang , Nagarajan Pratapkumar , Li Lei , Yi Allen Y.
Published: March 2007

An embossing strategy involving a hot station and a cold station for sequentially heating and cooling the embossing tool was investigated to reduce cycle times in hot embossing polymer microstructures. Experimental studies showed that aluminum stamps with a thickness of 1.4 mm can be rapidly heated from room temperature to 200°C in 3 s using contact heating against a hot station at 250°C. Microchannels and microlenses were successfully embossed onto high‐density polyethylene and acrylonitrile–butadiene–styrene substrates using a heating time less than 3 s and a total cycle time around 10 s. The two‐station embossing process for the microlens was also numerically studied. The simulated filling behavior agreed with the experimental observation and the predicted thermal and deformation history of the polymer offered a good explanation on the experimentally observed process characteristics. POLYM. ENG. SCI., 47:530–539, 2007. © 2007 Society of Plastics Engineers.
Crystallization of poly(vinyl alcohol) during solvent removal: Infrared characterization and mathematical modeling
Authors: Wong Sim‐Siong , Altinkaya Sacide Alsoy , Mallapragada Surya K.
Published: March 2007

Crystallization of semicrystalline polymer films during drying has a significant effect on the rate of solvent removal. Understanding and controlling the crystallization kinetics is important in controlling residual solvent levels and drying kinetics. The degree of crystallinity of the poly(vinyl alcohol) films during multicomponent drying was investigated using Fourier transform infrared spectroscopy (FTIR). The 1141 cm−1 band is sensitive to the degree of crystallinity of the polymer and the growth of intensity of this band was monitored as drying progressed. The results from the FTIR studies were comparable to the results obtained from differential scanning calorimetry. Studies were conducted to test the effect of initial solvent composition (water–methanol mixture), drying temperature, and polymer molecular weight on the rate of crystallization and the final crystallinity of the films. An increase in initial methanol composition increased the crystallization rate but did not affect the final degree of crystallinity. An increase in drying temperature and decrease in polymer molecular weight increased the rate of crystallization as well as the final degree of crystallinity. Based on the experimental data, rate constants for crystallization kinetics were extracted from our previously developed model based on free volume theory. The experimental data and the simulation results showed good agreement. The ability of the free volume theory to illustrate the crystallization behavior validated the model and improved its capability. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 930–935, 2007
Molecular dynamics simulation of water diffusion inside an amorphous polyacrylate latex film
Authors: Chen Zhengxia , Gu Qiang , Zou Haifeng , Zhao Tianqi , Wang Hongyan
Published: March 2007

Molecular dynamics simulations were applied to investigate the diffusion behaviors of water molecules at temperatures ranging from 323 to 443 K inside amorphous polyacrylate. The results showed that the simulated diffusion coefficients and activation energies were similar to those of experiments. Moreover, the activation energy of water molecules at high temperatures was higher than that at low temperatures by 3.16 kcal mol−1, which was close to the hydrogen‐bonding energy between water and polyacrylate. An analysis of the experimental desorption curves of water molecules and their activation energies has confirmed that there are two forms of water molecules inside rubbery polyacrylate, namely, free water and bound water. In addition, it has been concluded that bound water molecules move from one polar group of polyacrylate to another, and this is followed by occasional jumps. Simulated information is very helpful in designing new polyacrylate latex systems and optimizing existent polyacrylate systems. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 884–891, 2007
Structure and mechanical properties of poly(L‐lactic acid) crystals and fibers
Authors: de Oca H. Montes , Ward I. M.
Published: March 2007

The elastic constants of poly(L‐lactic acid) (PLLA) crystals are reported on the basis of a commercial software package and the published crystal structure of the α form. A chain modulus of 36 GPa and a shear modulus of 3 GPa have been obtained for cylindrically symmetric aggregates of perfectly oriented crystals. The helical conformation of the PLLA molecule reduces the stiffness in the chain axis direction because bond rotation plays a significant role in the deformation. X‐ray crystal strain measurements suggest that shear of the α crystal parallel to the helix axis is the easiest mode of deformation, in agreement with the expectations obtained from the low shear modulus of 3 GPa obtained from the theoretical calculations. A combination of small‐ and wide‐angle X‐ray scattering, differential scanning calorimetry, dynamic mechanical thermal analysis, and shrinkage measurements has been used to characterize the structure that develops and the crystal transformation that occurs during fiber processing. The structure that develops during processing very much depends on the crystal transformation, and a structural model is proposed for fibers at different degrees of plastic deformation. The transformation of the α crystal into the β form and vice versa is governed primarily by shear along the helix axis because the chains must shear past each other during the crystal transformation, disrupting the lamellar packing. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 892–902, 2007
Optical transitions in pairs of trivalent ion–interstitial fluorine in alkaline‐earth fluorides
Authors: Radzhabov E. , Nepomnyashchikh A. , Kirm M.
Published: March 2007

Absorption, excitation in vacuum ultraviolet region, emission and decay of emission of alkaline‐earth crystals (CaF2, SrF2, BaF2) doped by different concentrations of YF3 or LaF3 were studied. New emission bands in the region 3–6 eV and excitation bands just below exciton edges were observed. Unempirical Hartree–Fock and density functional calculations of alkaline‐earth crystal clusters containing Y or La impurity were performed. We concluded that observed optical bands belong to transitions between interstitial fluorine and trivalent metal parts of pairs Me3+–F–i. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electronic structure and spectroscopic properties of interstitial anions in the nanoporous complex oxide 12CaO·7Al2O3
Authors: Sushko P. V. , Muñoz Ramo D. , Shluger A. L.
Published: March 2007

A novel nano‐porous oxide 12CaO·7Al2O3 (C12A7) can host a large concentration of interstitial ions, which are present in high concentrations of the order of 1021 cm–3. We use ab initio calculations and an embedded cluster approach to investigate the effect of the interstitial ions on the optical absorption of C12A7. It is demonstrated that the position of the absorption edge can shift in the range of at least 1.5 eV depending on the chemical composition of different interstitial ions. This property of C12A7 can be used for fabrication of materials with tuneable band gaps on the basis of the same lattice host. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Localization and movement of native interstitials in chlorinated SrCl2:Fe crystals
Authors: Ghica D. , Nistor S. V. , Goovaerts E.
Published: March 2007

The formation of the electron trapped Fe+(IV) centre, produced by X‐ray irradiation at 80 K and further annealing at temperatures of up to 700 K in chlorinated SrCl2:Fe crystals, has been investigated by Electron Paramagnetic Resonance. Our studies report the transformation of the monoclinic Fe+(III) centre into the axial Fe+(IV) centre above 450 K. The formation of the Fe+(IV) centre is attributed to the presence and thermally activated movement of neighbouring interstitial chlorine and alkali impurity Na+ ions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum fluctuation and the magnetically structural symmetry in ferrimagnetic superlattices
Authors: Qiu Rong‐ke , Zhang Zhi‐dong
Published: March 2007

The magnetization and the quantum fluctuations in several ferrimagnetic superlattices consisting of 2–6 different magnetic sublayers are studied by employing Holstein–Primakoff transformations and Green's functions technique only for zero temperature. Investigating ferrimagnetic superlattices with different magnetic sublayers and different spin configurations, we find that when some of spin quantum numbers are adjusted, some sublayer magnetizations at zero‐temperature exhibit a minimum, correspondingly, the quantum fluctuation of the system exhibits a maximum point. Different spin configurations have different quantum fluctuations of the system. The maximum point of the quantum fluctuation of the system is related with higher symmetry of the system. It differs from the symmetry of crystallographic point‐groups or space‐groups, but belongs to the type III Shubnikou group of magnetic group, which describes antiferromagnetic or ferrimagnetic state. We define it as the magnetically structural symmetry. The higher the magnetically structural symmetry of the system is, the stronger the quantum fluctuation of the system is, for varying spin quantum numbers and different spin configurations. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Elastic and piezoelectric fields in quantum wire semiconductor structures – A boundary integral equation analysis
Authors: Pan E. , Albrecht J. D. , Zhang Y.
Published: March 2007

This paper presents a rigorous analysis on the elastic and piezoelectric fields in quantum wire (QWR) semiconductor structures using the accurate boundary integral equation method. The materials modelled include both zincblende and wurtzite III–V semiconductors, and both the well‐accepted inclusion and structural inhomogeneity models are discussed. While the difference in the strain field between the inclusion and inhomogeneity models is consistent with previously published results, within about 10%, the difference in the induced piezoelectric fields between these two models can be very large, sometimes even with different signs (for zincblende semiconductors). The electric field distribution in polygonal QWRs with different sides is also studied and it is found that the electric field in triangular and square QWRs can be very different from the fields in polygonal QWRs with more than four sides. These findings should provide important considerations and trend analyses for both growth and modelling associated with QWR semiconductor structures. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Specification and patterning of the animal‐vegetal axis in sea urchins by the canonical Wnt signaling pathway
Authors: Kumburegama Shalika , Wikramanayake Athula H.
Published: March 2007

Pattern formation along the sea urchin A‐V axis is initiated by the selective activation of the canonical Wnt signaling pathway in vegetal blastomeres. Activation of this pathway is essential for deployment of the endomesoderm gene regulatory network (EGRN), and for pattern formation along the entire A‐V axis. During early embryogenesis the canonical Wnt signaling pathway is selectively activated by Dishevelled (Dsh), a critical activator of the Wnt pathway. Dsh is highly enriched in vesicular structures at the vegetal pole in eggs and early embryos, and selective activation of this protein leads to the nuclearization of β‐catenin in the endomesoderm. Following activation of canonical Wnt signaling by Dsh, signaling by β‐catenin and the Lef/Tcf transcription factors regulates endomesoderm specification by activating the EGRN. One critical early target of nuclear β‐catenin is Wnt8, which is selectively expressed in the micromeres at the 16‐cell stage and in the macromeres one cleavage division later. Wnt8 signaling is not required for the endomesoderm‐inducing activity of the micromeres, but this protein regulates primary mesenchyme cell differentiation. Within the endomesodermal domain Wnt8 regulates the later specification of endoderm and mesoderm. These results have highlighted the important role of the canonical Wnt signaling pathway in patterning the A‐V axis in the sea urchin embryo, and have strongly suggested that this axis is initially specified by a cytoplasmic/cytoarchitectural mechanism to activate Dsh in vegetal blastomeres. Additionally, this work along with work in vertebrates and cnidarians has shown that the canonical Wnt pathway plays a conserved role in early pattern formation in metazoan embryos.
Reference ranges for tissue Doppler measures of maternal systolic and diastolic left ventricular function
Authors: Bamfo J. E. A. K. , Kametas N. A. , Nicolaides K. H. , Chambers J. B.
Published: March 2007

Objectives

Tissue Doppler imaging (TDI) is an echocardiographic technique that evaluates longitudinal myocardial tissue velocities during left ventricular systolic and diastolic function, relatively independently of loading conditions. Limited data are available regarding maternal cardiac function using TDI. The aim of this study was to construct reference charts for TDI indices in normal pregnancy.

Methods

This was a cross‐sectional study on 104 pregnant women at 11–38 weeks of gestation and 19 non‐pregnant controls. Doppler echocardiography was used to assess transmitral inflow velocities during diastole (peak velocity of early (E) and late (A) atrial filling), whilst TDI at the septal and lateral margins of the mitral annulus measured diastolic velocities (peak velocity of early (E′) and late (A′) diastolic filling) and peak systolic velocity (S′). The left ventricular filling index (E : E′ ratio) was derived. The Tei index (ratio of isovolumetric time to ejection time) was measured.

Results

Systolic function assessed by TDI S′ velocity was unaltered at the septal and lateral margins, although S′ velocity at the lateral margin was higher (12%, P = 0.028) in the first two trimesters, compared to non‐pregnant controls. Diastolic function was modified as demonstrated by an increase in A velocity (P P = 0.024). Similarly, A′ increased at the septal and lateral margins ( P < 0.001 and P = 0.02, respectively), resulting in a decrease in E′ : A′ ratios at the septal and lateral mitral margins ( P = 0.001 and P = 0.001, respectively). E : E′ at both mitral margins and Tei index were unaltered.

Conclusion

This study gives normal ranges for TDI indices in pregnancy. TDI demonstrated modified longitudinal systolic and diastolic function. Future studies will evaluate the potential of this technique in pregnancies complicated by hypertension and cardiac disease. Copyright © 2007 ISUOG. Published by John Wiley & Sons, Ltd.
Beta‐diversity of lepidopteran larval communities in a Japanese temperate forest: effects of phenology and tree species
Authors: Murakami Masashi , Ichie Tomoaki , Hirao Toshihide
Published: March 2007

The specialization of herbivores among tree species is poorly understood despite its fundamental importance as a factor regulating diversity. To examine the effect of tree species on larval community structure, the larval communities in 10 temperate deciduous tree species that differed in leaf emergence pattern (flush‐ vs. intermediate‐type) were seasonally surveyed. The newly developed soft, nitrogen‐rich leaves of all species became tough and nitrogen‐poor as the season progressed. Following the changes in leaf quality, two distinct seasonal lepidopteran larval communities emerged, with a marked turnover in early July. The beta diversity, or dissimilarity, of species composition in the larval communities among tree species was higher in summer than in spring. These results imply that the lepidopteran larval communities as a whole were supported by alpha diversity in spring and by beta diversity in summer, demonstrating that the plant diversity of this forest could support a caterpillar community. We examined the importance of spatio‐temporal variations in leaf quality within and among tree species in promoting herbivore diversity, although other factors, such as tree species phylogeny and predators, may also have a large effect on lepidopteran larval communities.
Paediatric airway emergencies in Northern Ireland, 1990–2003
Authors: Devlin B , Golchin K , Adair R
Published: March 2007

The management of paediatric airway emergencies is part of ENT practice. The most common conditions are acute viral laryngotracheobronchitis (croup), acute epiglottitis and bacterial tracheitis. Management of these conditions is significantly different and accurate diagnosis is crucial. We performed a retrospective analysis of all acute airway admissions to the paediatric intensive care unit (PICU) at the Royal Belfast Hospital for Sick Children from 1990 to 2003. The results showed a gradual decrease in the number of admissions due to croup. Acute epiglottitis admissions decreased markedly after 1992 but rose again in 2000, with a peak in 2002. Bacterial tracheitis is now the most common paediatric airway emergency requiring PICU admission and its incidence has been steadily increasing since 1990, peaking in 2003. The total number of admissions showed little change over the 14-year period audited. The significant shift in the nature of these conditions and these findings confirm the ongoing requirement for caution in dealing with a suspected airway emergency.
Why are most buildings rectangular?
Authors: Steadman Philip
Published: March 2007

The constraints of packing rooms together, and the flexibility of dimensioning allowed by rectangular arrangements, explain the predominance of the right angle in architectural plans.
The dangers of decorum
Authors: Anstey Tim
Published: March 2007

Decorum, ‘appropriateness’, seems deeply embedded in the psyche of architects as a means to justify their actions. This essay considers the shifting significance of this term for architectural discourse.
Iron supplement use among Danish pregnant women
Authors: Knudsen Vibeke K , Hansen Harald S , Ovesen Lars , Mikkelsen Tina B , Olsen Sjurður F
Published: March 2007

Objectives

To evaluate compliance with the national recommendation on supplemental iron to all pregnant women in Denmark and to explore differences between compliers and non-compliers with respect to dietary habits and other lifestyle factors.

Design

Intake of supplemental iron from pure iron supplements and from multivitamin and mineral preparations was estimated in mid-pregnancy.

Setting

Nationwide cohort study, the Danish National Birth Cohort (DNBC), comprising more than 100 000 women recruited in early pregnancy.

Subjects

Information on diet and dietary supplements was available for 54 371 women. Of these, information on lifestyle factors was available for 50 902 women.

Results

A high compliance with the recommendation was found, as approximately 77% of the women reported use of iron supplements during pregnancy. However, many of the compliers did not obtain the recommended doses of iron, which can partly be explained by the lack of iron preparations of appropriate doses available on the Danish market. Compliance with the recommendation was associated with age above 20 years, primiparity, body mass index < 30 kg m− 2, non-smoking and long education. No major differences were seen in dietary intake between compliers and non-compliers.

Conclusion

Overall, a high compliance rate was found among participants of the DNBC but a clarification on daily dose is needed, and more concern should be paid to vulnerable groups such as young, smoking women and women with no or short education.
Optimization of Bioreactor Using Metabolic Control Analysis Approach
Authors: Konde Kakasaheb S. , Modak Jayant M.
Published: March 2007

A new methodology based on a metabolic control analysis (MCA) approach is developed for the optimization of continuous cascade bioreactor system. A general framework for representation of a cascade bioreactor system consisting of a large number of reactors as a single network is proposed. The kinetic and transport processes occurring in the system are represented as a reaction network with appropriate stoichiometry. Such representation of the bioreactor systems makes it amenable to the direct application of the MCA approach. The process sensitivity information is extracted using MCA methodology in the form of flux and concentration control coefficients. The process sensitivity information is shown to be a useful guide for determining the choice of decision variables for the purpose of optimization. A generalized problem of optimization of the bioreactor is formulated in which the decision variables are the operating conditions and kinetic parameters. The gradient of the objective function to be maximized with respect to all decision variables is obtained in the form of response coefficients. This gradient information can be used in any gradient‐based optimization algorithm. The efficiency of the proposed technique is demonstrated with two examples taken from literature: biotransformation of crotonobetaine and alcohol fermentation in cascade bioreactor system.
Nearest‐neighbor analysis of small features on Mars: Applications to tumuli and rootless cones
Authors: Baloga S. M. , Glaze L. S. , Bruno B. C.
Published: March 2007

Fields of low relief cones, domes, and mounds on Mars have been interpreted as tumuli, rootless cones, and pingos. The spatial distribution of such features can be characterized by their nearest‐neighbor (NN) distances. The NN distributions can provide insight into the physical processes that affected field formation and can possibly provide a future diagnostic of the feature type present on Mars. The conventional approach for analyzing the observed NN distribution is based on the Poisson probability distribution and uses one statistic, c. Our simulations of spatial randomness show that there is an unrecognized bias in c that often leads to erroneous conclusions. Three alternative extensions of the Poisson distribution are proposed here. The first accounts for a minimum threshold on the size of features discerned, the second considers the scavenging of the resources necessary to form neighboring features (e.g., inflation pressurization and subsurface volatiles), and the third models self‐limiting growth of the feature population. Three statistical tests are proposed to improve the conventional NN analysis. We provide the critical regions needed to perform these tests for common sample sizes of these geologic features. Our methodology is applied to tumuli at Mauna Ulu, Hawaii, and conjectured tumuli and rootless cones on Mars. Each example exhibits a different aspect of spatial randomness. These applications suggest avenues for further field and theoretical studies to develop this approach as a remote‐sensing diagnostic.
Flux of dissolved organic carbon from U.K. rivers
Authors: Worrall F. , Burt T. P.
Published: March 2007

The rise in dissolved organic carbon (DOC) concentrations in the Northern Hemisphere in recent decades has been taken as indicative of increased turnover of terrestrial carbon and in particular in the vital reserve of peat. Hypotheses for this rise have been hotly debated in the literature. This study proposes that, although trends in concentration have been the main focus of attention, it is trends in DOC flux that need to be examined to understand changes in terrestrial carbon storage. This study uses data from 208 rivers over the period 1975–2003 to calculate the trend of DOC flux from Great Britain. The DOC flux peaks at 1.68 Mt C/yr, or an export of 6.6 tonnes C/km2/yr. The trend in flux is inconsistent with the pattern of atmospheric deposition, but regression analysis shows that the major control is hydrological throughput followed by an underlying upward, linear temporal trend. There is a small but significant effect ascribable to drought and storage effects. This suggests that there is additional biogeochemical production as a result of drought but that the overwhelming control in DOC flux is controlled by hydrological throughput overprinting an underlying increase in trend in DOC production. The underlying trend is consistent with increases in air temperature and or atmospheric CO2.