bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of molecular weight and temperature on physical aging of thin glassy poly(2,6‐dimethyl‐1,4‐phenylene oxide) films
Authors: Huang Y. , Paul D. R. 
Published: April 2007

AbstractThe effects of polymer molecular weight and temperature on the physical aging of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) is examined. Gas permeability and refractive index were monitored during the aging process for PPO film samples at three aging temperatures below the glass transition temperature. Comparisons between the two samples of PPO that differ widely in molecular weight reveal an insignificant difference, which support the notion that above a critical molecular weight range there is little influence on aging rate. Increased temperature, over the limited range of 35–55 °C, results in higher aging rates for films made from both PPO materials. The rate of aging decreases strongly with increasing film thickness over the range examined, ∼0.4–25 μm. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1390–1398, 2007
Increased expression and differential phosphorylation of stathmin may promote prostate cancer progression
Authors: Ghosh Ritwik , Gu Guangyu , Tillman Erin , Yuan Jialing , Wang Yongqing , Fazli Ladan , Rennie Paul S. , Kasper Susan 
Published: April 2007

AbstractBACKGROUNDProteins which regulate normal development may promote tumorigenesis, tumor progression, or metastasis through dysregulation of these functions. We postulate that proteins, which regulate prostate growth also promote prostate cancer (PCa) progression.METHODSTwo Dimensional Gel Electrophoresis was utilized to compare patterns of protein expression in 12T‐7f prostates (LPB‐Tag mouse model for PCa) during tumor development and progression with those of normal developing and adult wild type CD‐1 prostates. Stathmin expression and phosphorylation patterns were analyzed in mouse and human PCa cell lines as well as in human PCa tissue arrays.RESULTSStathmin was identified by two‐dimensional gel electrophoresis and mass spectrometry. Stathmin levels increase early during normal mouse prostate development and again during prostate tumor development and progression. In human prostate adenocarcinoma, stathmin increases in Gleason pattern 5. Further, stathmin is differentially phosphorylated in androgen‐dependent LNCaP cells compared to androgen‐independent PC‐3 and DU145 cells. This differential phosphorylation is modulated by androgen and anti‐androgen treatment.CONCLUSIONStathmin expression is highest when the prostate is undergoing morphogenesis or tumorigenesis and these processes may be regulated through differential phosphorylation. Furthermore, modulation of stathmin phosphorylation may correlate with the development of androgen‐independent PCa. Prostate 67: 1038–1052, 2007. © 2007 Wiley‐Liss, Inc.
Feasibility study of adjustment for contamination and non‐compliance in a prostate cancer screening trial
Authors: Roemeling Stijn , Roobol Monique J. , Otto Suzie J. , Habbema Dik F. , Gosselaar Claartje , Lous Jan J. , Cuzick Jack , Schröder Fritz H. 
Published: April 2007

AbstractBACKGROUNDThe use of PSA as a screening test has become increasingly prevalent in the general population and therefore also in the control arm of the European Randomized study of Screening for Prostate Cancer (ERSPC). We present a feasibility study and impact simulation of a secondary analysis, which imitates a situation where all participants in the study are managed according to their random assignment.METHODSThe results of the Rotterdam section of the ERSPC were adjusted for contamination and non‐compliance according to Cuzick et al. [Stat Med 1997; 16:1017–1029]. Endpoints of this analysis were simulated reductions in prostate cancer mortality.RESULTSOf the men allocated to the screen arm, 27.1% were non‐compliant. In the control arm 30.7% had their PSA‐level measured by a general practitioner (GP) (i.e., contamination). For a scenario in which the intention‐to‐screen analysis was assumed to give a decrease in the mortality in the men randomized to screening of 6.7%, the secondary analysis resulted in a decrease of 16.1% for those actually screened.CONCLUSIONAlthough the definition of contamination as “PSA ever tested” gives an indication of the proportion of contamination, it will be important to differentiate the screening use of PSA from its diagnostic use. For the rest, adjustment for non‐compliance and contamination was shown to be feasible in this prostate cancer screening trial. It can therefore be used to carry out a secondary analysis on the definitive outcome of the ERSPC and will provide accurate information for those men who are in fact screened. Prostate 67: 1053–1060, 2007. © 2007 Wiley‐Liss, Inc.
Ab‐initio investigation of structural, electronic and optical properties for three phases of ZnO compound
Authors: Charifi Z. , Baaziz H. , Hussain Reshak Ali 
Published: April 2007

AbstractThe complex density‐functional theory (DFT) calculations of structural, electronic and optical properties for the three phases: wurtzite (B4), zincblende (B3) and rocksalt (B1) of ZnO compound have been reported using the full‐potential linearized‐augmented plane‐wave (FP‐LAPW) method as implemented in the WIEN2k code. We employed both the local‐density approximation (LDA) and the generalized‐gradient approximation (GGA), which is based on exchange–correlation energy optimization to calculate the total energy. Also, we have used the Engel–Vosko GGA formalism, which optimizes the corresponding potential for band‐structure calculations. The 3d orbitals of the Zn atom were treated as the valence band. The calculated structural properties (equilibrium lattice constant, bulk modulus, etc.) of the wurtzite and rocksalt phases are in good agreement with experiment. The B4 structure of ZnO is found to transform to the B1 structure with a large volume collapse of about 17%. The phase transition pressure obtained by using LDA is about 9.93 in good agreement with the experimental data. B1‐ZnO is shown to be an indirect bandgap semiconductor with a bandgap of 1.47 eV, which is significantly smaller than the experimental value (2.45 ± 0.15 eV). While B3 and B1 phases have direct bandgap semiconductors with bandgaps 1.46 and 1.57 eV, respectively. Also, we have presented the results of the effective masses. We present calculations of the frequency‐dependent complex dielectric function ε (ω) and it zero‐frequency limit ε1(0). The optical properties of B4 phase show considerable anisotropic between the two components. The reflectivity spectra has been calculated and compared with the available experimental data. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of the transport properties of a molecular junction as a function of the distance between the leads
Authors: García‐Suárez Víctor M. , Kostyrko Tomasz , Bailey Steven , Lambert Colin , Bułka Bogdan R. 
Published: April 2007

AbstractWe consider a model of a molecular junction made of BDT (benzene dithiol) molecule trapped between two Au(100) leads. Using the ab initio approach implemented in the SIESTA package we look for the optimal configurations of the molecule as a function of the distance between the leads. We find that for distances long enough the energy of the system is minimized when the molecule is bonded asymmetrically, i.e. chemisorbed to one of the leads, whereas for distances shorter than 12 Å the energy is minimized when the molecule sits in the middle between the leads. We discuss possible consequences of the above findings for the transport properties of the junction. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Proton spin system in pentacene and its interaction with photoexcited triplet electron spin
Authors: Labuz M. , Kuzma M. 
Published: April 2007

AbstractReading of single spin states is the main experimental problem in quantum computing. Pentacene is one of a few molecules on which the optical read‐out of single spin experiments were performed. The shape of optical single molecule spectroscopy (ODMR) signal depends on an interaction of triplet state of two unpaired electron spins with proton bath. These protons form a Heisenberg chain withN= 14 nodes. We investigate the symmetry of this system in selected inversed spin sectors of 214nuclear spin configurations. In particular all exact Bethe solutions for two reversed spins have been derived. The interaction of electron and proton spin systems has been addressed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin–orbital entanglement near quantum phase transitions
Authors: Oleś Andrzej M. , Horsch Peter , Khaliullin Giniyat 
Published: April 2007

AbstractSpin–orbital entanglement in the ground state of a one‐dimensional SU(2) ⊗ SU(2) spin–orbital model is analyzed using exact diagonalization of finite chains. For S = 1/2 spins and T = 1/2 pseudospins one finds that the quantum entanglement is similar at the SU(4) symmetry point and in the spin–orbital valence bond state. We also show that quantum transitions in spin–orbital models turn out to be continuous under certain circumstances, in constrast to the discontinuous transitions in spin models with SU(2) symmetry. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of the next‐nearest neighbor hopping on the stability and band structure of the incommensurate phases in the cuprates
Authors: Raczkowski Marcin , Frésard Raymond , Oleś Andrzej M. 
Published: April 2007

AbstractUsing a spin‐rotation invariant version of the slave‐boson approach we investigate the relative stability and band structure of various incommensurate phases in the cuprates. Our findings obtained in the Hubbard model with next‐nearest neighbor hopping –t′/t≃ 0.15, as appropriate for the La2–xSrxCuO4family, support the formation of diagonal (vertical) stripe phases in the doping regimex= 1/16 (x= 1/8), respectively. In contrast, based on the fact that a larger value –t′/t= 0.3 expected for YBa2Cu3O6+δtriggers a crossover to the diagonal (1,1) spiral phase at increasing doping, we argue that it might explain why the static charge order has been detected in YBa2Cu3O6+δonly in the highly underdoped regime. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reduction in defect density over whole area of (1$ \bar 1 $00) m ‐plane GaN using one‐sidewall seeded epitaxial lateral overgrowth
Authors: Kawashima T. , Nagai T. , Iida D. , Miura A. , Okadome Y. , Tsuchiya Y. , Iwaya M. , Kamiyama S. , Amano H. , Akasaki I. 
Published: April 2007

AbstractWe succeeded in growing low‐defect‐density m ‐plane GaN on grooved m ‐plane GaN with SiO2 masks on the terrace region. By changing the V/III ratio, we were able to increase the growth rate of GaN on one sidewall, thereby achieving one‐sidedwall lateral growth. Dislocations and stacking faults were decreased markedly over the whole area. The densities of dislocations and stacking faults were 1.3 × 107 (cm–2) and <2.6 × 104 (cm–1), respectively. The photoluminescence intensity was 213 times higher than that of an m ‐plane GaN template on an m ‐plane 4H‐SiC substrate. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Antisite defect‐related luminescence in (LaLu)3Lu2Ga3O12 garnet single crystals
Authors: Zorenko Yu. , Voloshynovskii A. , Vistovsky V. , Grinberg M. , Kornylo A. , Łukasiewicz T. , Świrkowicz M. 
Published: April 2007

AbstractIntrinsic luminescence of the undoped (LaLu)3Lu2Ga3O12 garnet (LLGG) single crystals with high concentration of LuLa antisite defects (AD) has been studied for the first time under excitation by 1.5 ns pulse X‐ray radiation. It has been found that the host luminescence of LLGG crystal consists of two emission bands in the UV range. The band peaked at 3.80 eV at 77 K has been related to the luminescence of localized excitons (LE) perturbed by the presence of AD whereas the band peaked at 3.37 eV has been related to the radiative annihilation of bound‐state excitons localized directly at LuLa AD. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantitative carbamylation as a stable isotopic labeling method for comparative proteomics
Authors: Angel Peggi M. , Orlando Ron 
Published: April 2007

AbstractA method was developed that uses urea to both solublize and isotopically label biological samples for comparative proteomics. This approach uses either light or heavy urea (12CHN2O or 13CHN2O, respectively) at a concentration of 8 M and a pH of 7 to dissolve the samples prior to digestion. After the sample is digested using standard proteomic protocols and dried, isotopic labeling is completed by resuspending the sample in a solution of 8 M urea at a pH of 8.5, using the same isotopic species of urea as used for digestion and incubating for 4 h at 80°C. Under these conditions, carbamylation occurs only on the primary amines of the peptides. The effects of complete carbamylation on matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) and electrospray ionization tandem mass spectrometry (ESI‐MS/MS) (collision‐induced dissociation (CID)) were examined. Peptides that had a C‐terminal carbamylated lysine residue were found to have a reduced intensity when viewed by MALDI‐TOFMS. CID of a tryptic peptide that was carbamylated on both the N‐terminus and the C‐terminus was found to have a more uniform distribution of b‐ and y‐ions, as well as prominent ions from loss of water. Reversed‐phase chromatography coupled to ESI‐MS/MS was used to identify and quantify the isotopically labeled standard proteins, bovine serum albumin (BSA), bovine transferrin, and bovine alpha‐casein. Quantitative error between theoretical and observed data ranged from 1.7–10.0%. Relative standard deviations for protein quantitation ranged from 5.2–27.8% over a dynamic range from 0.1–10 (L/H). The development of a method utilizing urea‐assisted carbamylation of lysines and N‐termini to globally labeled samples for comparative proteomics may prove useful for samples that require a strong chaotrope prior to proteolysis. Copyright © 2007 John Wiley & Sons, Ltd.
Denaturation of α‐lactalbumin and ubiquitin studied by electrospray and laser spray
Authors: Nakamura Masana , Takamizawa Atsushi , Yamada Hideki , Hiraoka Kenzo , Akashi Satoko 
Published: April 2007

AbstractElectrospray and laser spray mass spectra of human α‐lactalbumin and bovine ubiquitin were studied, with an emphasis on the denaturation induced by laser spray. There were no remarkable differences in the electrospray and laser spray mass spectra for acidic and basic aqueous solutions of α‐lactalbumin in positive and negative modes of operations. This originates from the fact that this protein is tightly folded with four disulfide bonds. For ubiquitin, however, denaturation was induced by laser spray for the positive mode of operation and the [M+nH]n+ with a maximum of n = 13 was observed, i.e., all the acidic amino acid residues are fully neutralized (protonated). In contrast, the laser‐induced denaturation was not observed for the negative mode of operation, i.e., denaturation of ubiquitin is largely suppressed in the negatively charged liquid droplets. The marked difference observed in the positive and negative modes of operations for ubiquitin is ascribed to the difference in the susceptibility of side‐chain/main‐chain interactions in the positive‐ion excess and in the negative‐ion excess liquid droplets. That is, the interactions between the basic residues and main‐chain amide carbonyl groups (NH•••OC< or NH2•••OC<) which play an important role in stabilizing the protein structures are not so affected in the negative mode of operation but are weakened in the positive mode of operation. Copyright © 2007 John Wiley & Sons, Ltd.
Actuator fault diagnosis for uncertain linear systems using a high‐order sliding‐mode robust differentiator (HOSMRD)
Authors: Chen Weitian , Saif Mehrdad 
Published: April 2007

AbstractMany observer‐based fault diagnosis strategies proposed for linear systems, subject to unknown inputs, operate based on three assumptions. The first assumption is that the system under consideration is at least detectable. The second one is that the unknown inputs satisfy certain matching conditions. The third one, which is often implicit, is that the relative degrees from the generalized input vector, including both known and unknown inputs, to the outputs are no larger than one. If none of these assumptions are met, little result exists on how to carry out fault diagnosis. The purpose of this paper is to develop a novel actuator fault diagnosis scheme for a general class of linear systems subject to unknown inputs that can work without the mentioned three assumptions. Four actuator fault diagnosis problems related to fault detection, isolation, and estimation are formulated and studied. In order to solve these problems, an input–output relation, which involves only the outputs and their higher‐order derivatives, is derived. The posed problems are solved based on this relation via utilizing both the outputs and their higher‐order derivatives. Because only the outputs are measured, higher‐order output derivatives are estimated using the recently developed high‐order sliding‐mode robust differentiators (HOSMRDs). The first two fault detection and isolation problems are answered in terms of a concept called Generalized Actuator Fault Isolation IndeX (GAFIX), and it is proved that, under the condition that the derived input–output relation is used for fault diagnosis, actuator faults are detectable if and only if GAFIX⩾1, and l actuator faults can be isolated if and only if GAFIX⩾l+1. A method which can be used to estimate the faults is proposed for the fault estimation problem. To solve the last problem, an actuator fault diagnosis scheme is designed using both the measured outputs and their estimated derivatives obtained by HOSMRDs, and is presented in steps. Finally, an example is provided to show the effectiveness of our fault diagnosis scheme in terms of fault detection, isolation, and estimation. Copyright © 2007 John Wiley & Sons, Ltd.
Imaging of Silkworm Meiotic Chromosome by Atomic Force Microscopy
Authors: Narukawa J. , Yamamoto K. , Ohtani T. , Sugiyama S. 
Published: April 2007

AbstractAlthough structural information of mitotic chromosomes has been accumulated, little information is available for meiotic chromosome structures. Here, we applied atomic force microscopy (AFM) to investigate the ultrastructures of the silkworm, Bombyx mori, meiotic pachytene chromosome in its native state with nanometer scale resolution. Two levels of DNA folding were observed on the meiotic chromosome surface, 50–70 nm granules, which were considered to be 30 nm chromatin fibers, and spherical protrusions of 400–600 nm, which were considered to be chromomeres and arranged on the surface of the chromosome parallel to the chromosome longitudinal axis. These observations suggested that AFM study is an excellent approach for obtaining information concerning the silkworm pachytene chromosome higher order structure. SCANNING 29: 000‐V000, 2007. © 2007 Wiley Periodicals, Inc.
Skirting: A Limitation for the Performance of X‐ray Microanalysis in the Variable Pressure or Environmental Scanning Electron Microscope
Authors: Le Berre J. F. , Demopoulos G. P. , Gauvin R. 
Published: April 2007

AbstractThe variable pressure or environmental scanning electron microscope (VP‐SEM; ESEM) has become the microscope of choice for many scientists and technologists. Hence, the development of robust methods for X‐ray microanalysis, limited by skirting, has become critical. In this paper, two pressure variation correction methods (Doehne and Gauvin) are compared. Both of these methods appear to be effective; the results were found to be well within 10% of the values obtained at 0 Pa. The Doehne method is dependent on an empirical factor (D), therefore the accuracy of the results will depend on the accuracy of this value. Also the Doehne method is compromised by the nonlinearity of the response with pressure. The Gauvin method is more user‐friendly and more precise when considering the total range of pressure. SCANNING 29: 000‐V000, 2007. © 2007 Wiley Periodicals, Inc.
The questioning statistician
Authors: Finney D. J. 
Published: April 2007

AbstractEffective statistical help to biological and medical research demands thorough involvement of the statistician. The breadth of his activities can be illustrated by considering the questions he needs to discuss with his scientific colleagues in the course of planning a comparative experiment. The paper presents and comments on 22 such questions, showing their relation to the objectives of the experiment, the utilization of resources, and the subsequent statistical analysis. A final paragraph urges that proper attention to all these points forms an integral part of an ethical approach to experimentation.
A simple method based on broken‐line interpolation for displaying data from long‐term clinical trials
Authors: Gans Daniel J. 
Published: April 2007

AbstractIn displaying data from long‐term clinical studies, variation across patients in the times at which readings are recorded often presents a problem. A simple method for treating such data is proposed, which avoids arbitrary conventions and methodological difficulties inherent in other approaches. It is based on within‐patient broken‐line interpolation, and is easy to implement on a computer. The method is tested and compared to others with computer‐simulated data whose time‐pattern is known. Though the comparison is of limited scope, the method appears to compare favourably with the ‘closest‐reading’ and ‘window’ approaches.
The detection of adverse reactions to therapeutic drugs
Authors: Finney D. J. 
Published: April 2007

AbstractThe risk that a drug newly introduced into medical use will occasionally cause adverse reactions is neither negligible nor totally avoidable. Only well organized systems of monitoring can bring early detection and appropriate action. These in turn require either detailed supervision or spontaneous reporting. The paper is concerned with statistical inference from reports spontaneously submitted, and its logical limitations; it discusses strengths and weaknesses of the UK system, the detection process, and automated signalling.
Interpretation and estimation of summary ratios under heterogeneity
Authors: Greenland Sander 
Published: April 2007

AbstractOf the several types of summary odds ratios in use in epidemiology, only those proposed by Mantel and Haenszel and Miettinen do not assume homogeneity (constancy) of stratum‐specific parameters. Under heterogeneity, Miettinen's estimators consistently estimate meaningful epidemiologic parameters, whereas the asymptotic expectation of the Mantel‐Haenszel odds ratio varies according to irrelevant features of the sampling design. Although one can modify the Mantel‐Haenszel summary to overcome the latter problem, one can also extend the Miettinen estimators to sparse data and thus limit the use of Mantel‐Haenszel summaries to situations in which the homogeneity hypothesis is reasonable. This paper provides formulae for the extended Miettinen estimators and large‐sample variances and confidence limits for summary ratios under heterogeneity.