bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physical and mechanical properties of photopolymerized SBS–methacrylic monomer systems
Authors: Mateo J. L. , Calvo M. , Bosch P. 
Published: June 2003

AbstractAn exploratory study on physical and mechanical properties—transmittance, pendulum hardness, dynamic‐mechanical, and tensile—of photopolymerized styrene–butadiene–styrene block copolymer (SBS)–methacrylic monomer systems at different compositions was carried out. The insoluble and crosslinked polymerized systems prepared exhibit a high transmittance along the visible light region and retain the regular structure corresponding to the matrix (SBS), that is, the dynamic‐mechanical spectra show the two peaks corresponding to the PS and PB phases in the tan δ–temperature plot. Trapped radicals remain in the photopoymerized SBS–methacrylic monomer (tetra or hexafunctional) system, so when these systems are heated above their vitreous transition temperature, a postpolymerization reaction is produced that gives rise to an increase of both the crosslinking density and the storage modulus. The modulus and ultimate tensile strength of the polymerized SBS–hexanediol dimethacrylate (HDDMA) systems increase with increasing initial proportions of the dimethacrylate monomer; on the contrary, the percent elongation at break and toughness decrease with increasing proportions of initial dimethacrylate monomer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2857–2864, 2003
Design and performance evaluation of an hybrid reservation‐polling MAC protocol for power‐line communications
Authors: Bianchi G. , Tinnirello I. , Conigliaro G. 
Published: June 2003

AbstractThis paper presents an hybrid reservation‐polling MAC protocol able to effectively deal with the channel disturbances typical of Power‐line communication systems. Channel access is controlled by a scheduler running on a centralized station. Fast retransmission of corrupted packets is employed to achieve high performance on Power‐line channels characterized by frequent error bursts due to impulsive noise. The performance of our proposed mechanism are evaluated by means of simulation, for the more challenging case of time‐sensitive traffic sources (voice calls). Results show that the system efficiency is virtually not affected by lightly to moderately disturbed PLC channel. Moreover, by slightly reducing the system utilization, a target 1% packet loss ratio can be met even in the presence of severe channel disturbances. Copyright © 2003 John Wiley & Sons, Ltd.
Distributed MAC protocols and priority oriented scheduling for a PLC access network
Authors: Sundaresan S. , Anand S. , Srikanth S. , Krishnan C. N. 
Published: June 2003

AbstractIn this paper, we propose a distributed channel allocation scheme for the uplink data traffic and implement a priority oriented scheduling for the downlink data traffic for a powerline access type network. We study the performance of the uplink and downlink protocols in terms of the buffering probability, mean delay, statistical dropping probability and the number of subscriber stations supported. The distributed channel allocation scheme uses a modified carrier sensing mechanism and a centralized collision resolution scheme. We model the channel occupancy of uplink data calls using a continuous time Markov chain (CTMC). We derive the expressions for mean delay, statistical dropping probability, and utilization by solving the CTMC. We also perform extensive simulations to complement our analytical results. Our results indicate that, the distributed channel allocation approach achieves 10% improvement in spectrum utilization compared to a centralized reservation protocol. We also implement a priority oriented scheduling policy for the downlink data traffic. In the system we consider, the downlink channels are adaptively modulated based on their signal strength. We maximize the instantaneous link utilization by using MaxFlow algorithm. Simulation results for downlink scheduling show that the mean buffering delay for the real‐time variable bit rate traffic is zero and that the system supports 170 access stations. We also show that system with adaptive modulation achieves 26% savings in transmitted power compared to the system without adaptive modulation. Copyright © 2003 John Wiley & Sons, Ltd.
Differential acquired immune responsiveness to bacterial lipoproteins in Lyme disease‐resistant and ‐susceptible mouse strains
Authors: Ganapamo Frédéric , Dennis Vida A. , Philipp Mario T. 
Published: June 2003

AbstractWe investigated the effect of Borrelia burgdorferi lipoproteins (outer surface protein A) and the synthetic lipohexapeptide tripalmitoyl‐S‐glyceryl‐Cys‐Ser‐4(Lys) (Pam3‐Cys) on isolated lymph node (LN) cells from Lyme disease‐susceptible (C3H/HeJ) and ‐resistant (C57BL/6J) mice. Mice were either infected with B. burgdorferi for 1 week or left uninfected. Lipoprotein‐stimulated LN cells from infected C3H/HeJ mice produced significantly higher levels of the inflammatory cytokines IL‐6 and IFN‐γ than did cells from C57BL/6J mice. Cells from uninfected mice did not respond. No TNF‐α or IL‐1β were produced by LN cells from infected mice of either strain in response to lipoprotein or B. burgdorferi spirochetes. Unlike with IL‐6 or IFN‐γ, LN cells from either strain failed to produce IL‐10 in response to lipoproteins. However, the LN cells were able to produce this cytokine in response to B. burgdorferi spirochetes or after incubation with phorbol‐12‐myristate‐13‐acetate/ionomycin, anti‐CD3 antibody alone or anti‐CD3 combined with anti‐CD28 antibodies. Addition of exogenous IL‐10 to lipopeptide‐stimulated cultures significantly reduced IFN‐γ and IL‐6 production in a dose‐dependent fashion. This inhibition was more effective with cells from disease‐resistant C57BL/6J mice than with cells from disease‐susceptible C3H/HeJ mice. The proclivity to disease of the C3H/HeJ mouse could be simultaneously based on the phenomena of enhanced inflammatory responsiveness to lipoproteins and diminished ability to respond to IL‐10. An investigation of the determinants of these two phenomena could be used as a blueprint to elucidate the pathogenesis of Lyme disease in humans.
Caspase‐8 and caspase‐10 activate NF‐κB through RIP, NIK and IKKα kinases
Authors: Shikama Yoshiaki , Yamada Masao , Miyashita Toshiyuki 
Published: June 2003

AbstractNF‐κB regulates the expression of various genes involved in cell growth and differentiation, immune response and inhibition of apoptosis. Recently, some death effector domain (DED)‐containing proteins, such as FADD and c‐FLIP were reported to activate NF‐κB. We previously reported that the prodomain‐only isoforms of caspase‐8 and ‐10 (PDCasp8/10), containing two DED motifs, could inhibit Fas‐mediated apoptosis. Here, we demonstrate that these isoforms also activate NF‐κB, implying this to be one of the mechanisms by which these polypeptides inhibit apoptosis. The GST pull‐down assay revealed that, among upstream kinases that activate NF‐κB, only NIK and RIP, but not RICK or IKKα/β, could directly bind to PDCasp8/10. In addition, both modules ofDED in PDCasp8/10 were required for these interactions as well as NF‐κB activation. Experiments using a kinase‐dead mutant of IKKα and an RIP mutant lacking a kinase domain, both of whichfunction as dominant‐negative mutants for their wild‐type counterparts, blocked PDCasp8/10‐mediated NF‐κB activation. Using small interfering RNA technology, we further demonstrate that the down‐regulation of IKKα but not IKKβ significantly inhibits PDCasp8‐mediated NF‐κB activation. Taken together, these results suggest that caspase‐8 and ‐10 have roles in a non‐ or anti‐apoptotic signaling pathway leading to NF‐κB activation through RIP, NIK and IKKα.
Practical considerations of recombinant adeno‐associated virus‐mediated gene transfer for treatment of retinal degenerations
Authors: Shen Wei‐Yong , Lai Chooi‐May , Lai Yvonne K. Y. , Zhang Dan , Zaknich Tammy , Sutanto Erika N. , Constable Ian J. , Elizabeth Rakoczy P. 
Published: June 2003

AbstractBackgroundPhotoreceptor (PR) and retinal pigment epithelium (RPE) are the principal cell targets in retinal gene therapy. Recombinant adeno‐associated virus (rAAV) has emerged as a very promising vector for gene therapy in hereditary retinal diseases. Gene transfer at different stages of the disease is a practical consideration for future clinical application.MethodsA rAAV carrying the enhanced green fluorescent protein gene driven by a cytomegalovirus promoter was produced by either co‐infecting the 293 cell line with E1‐defective adenovirus and purified by CsCl2 density gradient (CsCl2‐rAAV), or by transfecting with an adenoviral helper plasmid and purified by iodixanol density gradient followed by heparin column chromatography (heparin‐rAAV). The impact of different virus preparations on the patterns of transgene expression was investigated after subretinal injection. Furthermore, rAAV‐mediated gene transfer was evaluated at both early and advanced stages of retinal degeneration in four disease models including the RCS rat, rd, RPE65−/− and cathepsin D mutant mice that are associated with PR‐ or RPE‐related gene defects.ResultsCsCl2‐rAAV predominantly transduced RPE and with less efficiency in PR. In contrast, heparin‐rAAV predominantly transduced PR but with much less efficiency in RPE. Subretinal injection of either rAAV preparation induced no changes to retinal morphology and retinal‐choroidal vasculature. The product of transgene, however, could be observed in multiple tracts in the brain. In the four disease models, target cells were efficiently transduced not only at the early stage, but also at the late stage of disease as long as the target cells were present.ConclusionsDifferent preparations of rAAV have an impact on the patterns of transgene expression after subretinal injection. Patients at advanced stages of retinal degeneration may still benefit from rAAV‐mediated gene therapy. The possible side effects of transgenic products on the central nervous system should be carefully monitored once therapeutic genes are employed. Copyright © 2003 John Wiley & Sons, Ltd.
Sendai virus vectors as an emerging negative‐strand RNA viral vector system
Authors: Bitzer Michael , Armeanu Sorin , Lauer Ulrich M. , Neubert Wolfgang J. 
Published: June 2003

AbstractThe power to manipulate the genome of negative‐strand RNA viruses, including the insertion of additional non‐viral genes, has led to the development of a new class of viral vectors for gene transfer approaches. The murine parainfluenza virus type I, or Sendai virus (SeV), has emerged as a prototype virus of this vector group, being employed in numerous in vitro as well as animal studies over the last few years. Extraordinary features of SeV are the remarkably brief contact time that is necessary for cellular uptake, a strong but adjustable expression of foreign genes, efficient infection in the respiratory tract despite a mucus layer, transduction of target cells being independent of the cell cycle, and an exclusively cytoplasmic replication cycle without any risk of chromosomal integration.In this review we describe the current knowledge of Sendai virus vector (SeVV) development as well as the results of first‐generation vector applications under both in vitro and in vivo conditions. So far, Sendai virus vectors have been identified to be a highly efficient transduction tool for a broad range of different tissues and applications. Future directions in vector design and development are discussed. Copyright © 2003 John Wiley & Sons, Ltd.
A robust incomplete factorization preconditioner for positive definite matrices
Authors: Benzi Michele , Tůma Miroslav 
Published: June 2003

AbstractWe describe a novel technique for computing a sparse incomplete factorization of a general symmetric positive definite matrix A. The factorization is not based on the Cholesky algorithm (or Gaussian elimination), but on A‐orthogonalization. Thus, the incomplete factorization always exists and can be computed without any diagonal modification. When used in conjunction with the conjugate gradient algorithm, the new preconditioner results in a reliable solver for highly ill‐conditioned linear systems. Comparisons with other incomplete factorization techniques using challenging linear systems from structural analysis and solid mechanics problems are presented. Copyright © 2003 John Wiley & Sons, Ltd.
An unstructured multigrid method based on geometric smoothness
Authors: Chow Edmond 
Published: June 2003

AbstractFor non‐M‐matrices, this paper proposes an unstructured multigrid method that only attempts to interpolate in the directions of geometric smoothness. These directions are determined by analysing samples of algebraically smooth error, e. Neighbouring grid points i and j are called smoothly coupled if ei and ej are consistently nearby in value. In addition, these differences may be used to define interpolation weights. These new ideas may be incorporated into the algebraic multigrid method. Test results show that the new method can have much lower grid and operator complexities compared to AMG, leading to lower solve timings. Published in 2003 by John Wiley & Sons, Ltd.
On a possible melting curve of C60 fullerite
Authors: Zubov V. I. , Rodrigues C. G. , Zubov I. V. 
Published: June 2003

AbstractWe study the thermodynamic properties of the high‐temperature modification of fullerites on the basis of the Girifalco intermolecular potential. In the present work, using Lindemann's melting criterion, we estimate a possible melting curve Tm(P) of C60 fullerite. To take into account the lattice anharmonicity, which has a strong effect at T > 700 K, we use the correlative method of unsymmetrized self‐consistent field. To check this approach, first we have applied it to solid Ar. In the range between its triple point Tt = 83.807 K and 260 K we obtained the mean square relative deviation from experimental data of about 0.7%. The melting curve for C60 fullerite has been calculated from the melting point at normal pressure estimated at 1500 K up to 15 kbar, which corresponds to Tm = 4000 K, i.e. to the temperature estimated by Kim and Tománek [Phys. Rev. Lett. 72, 2418 (1994)] as that of the decomposition of the C60 molecule itself. The temperature dependence of the melting pressure is approximated very well by the Simon equation (Pm(T)/bar – 1)/b = (T/T0)c with T0 = 1500 K, b = 6643.8, and c = 1.209. The temperature dependence of the molar volume along the melting curve is described by Vs(T) = Vs(T0) – 29.20 ln (T/T0.
Theoretical analysis of disorder effects on electronic and optical properties of the quaternary alloy In1–xGaxAsySb1–y epilayer on GaSb and InAs
Authors: Rabah M. , Sahraoui B. , Bouhafs B. , Abbar B. , Abid H. 
Published: June 2003

AbstractThe effects of structural and chemical disorder on electronic and optical properties of In1–xGaxAsySb1–y quaternary alloy are studied on the basis of a modified virtual crystal approximation calculated within a simple tight‐binding sp3s* theory, which incorporates relaxation parameters and compositional disorder as an effective potential. Using a minimal set of fitting parameters, we show that such an approach provides analytical results for calculating energy gaps and bowing parameters. The electronic structure are studied for In1–xGaxAsySb1–y (x = 0.5, y = 0.5) and In1–xGaxAsySb1–y lattice matched to GaSb and as well as to InAs. In addition, a method for calculating the refractive indices at energies below the direct band gap edge is presented. The photon energy dependence of the refractive index is calculated with the model of dielectric constants of semiconductors based on simplified models of the interband transitions. Also the composition dependence of the refractive index is discussed; the result indicates that the refractive index increases with alloying for an In1–xGaxAsySb1–y lattice matched to InAs and GaSb. The lattice thermal resistivity has been calculated using interpolation schemes. The result indicates that the thermal resistivity of an In1–xGaxAsySb1–y lattice matched to InAs and GaSb for the composition of (0 ≤ x ≤ 1) increases markedly with alloying and exhibits a maximum value of about 41 W–1 deg cm at an alloying composition of x ≅ 0.45 and about 40 W–1 deg cm at an alloying composition of x ≅ 0.50 for InGaAsSb on a substrate of GaSb and InAs, respectively.
Preclinical removable partial dentures curriculum survey
Authors: Rashedi Behnoush , Petropoulos Vicki C. 
Published: June 2003

Purpose In 2001, a survey of U.S. dental schools was conducted to determine the curricular structure, teaching philosophies, and techniques used in preclinical removable partial denture (RPD) courses and to also establish what newer educational techniques and materials are currently being used by U.S. dental schools.Materials and Methods The questionnaire was mailed to the chairpersons of the prosthodontic/restorative departments of 54 U.S. dental schools. Of these, 43 schools returned the completed survey, resulting in a response rate of 80%. The mean, median, and range of responses were computed where applicable.Results Results from this survey show that the mean student‐to‐faculty ratio in the preclinical RPD course was 12:1, with a median of 10:1 and a range of 6:1 to 27:1. The mean number of laboratory hours was 55, with a median of 50 and a range of 13.5 to 120. The mean number of lecture hours reported was 21, with a median of 20.5 and a range 10 to 60. The mean number of practical examinations was 2, with a median of 3 and a range of 0 to 8. The mean number of written examinations given was 2, with a median of 2 and a range of 1 to 6. Ninety‐five percent of the schools have prosthodontists teaching this course. The mean number of months that this course is taught is 4.4 months, with a median of 4 and a range of 1.5 to 10. Fifty‐five percent of the schools used the Hanau semiadjustable articulator. One hundred percent of the schools teach students to use a surveyor when designing an RPD, and 84% percent of the schools teach the Krol or the Kratochvil RPI design or a combination of the 2 designs.Conclusions Preclinical RPD educational programs vary from school to school, yet a large percentage of schools agree on certain topics. Only 19% of dental schools are incorporating new technologies, such as the use of the internet, in their preclinical RPD curriculum.
Sympathetic nerve activity does not reduce proprioceptive acuity in humans
Authors: Matre D. , Knardahl S. 
Published: June 2003

AbstractAim:  Proprioception is essential in coordinating body segments and controlling muscles to perform movements. Animal studies have reported reduced muscle spindle sensitivity in jaw muscles during stimulation of sympathetic nerves. A stress‐induced distortion of proprioception has been suggested that could lead to reduced fine control of movement and inefficient muscle use. The present study investigated whether increased muscle sympathetic activation alter human proprioception.Method:  Movement detection thresholds of the right ankle were determined in eight healthy subjects, before and during two conditions known to increase muscle sympathetic activity (MSA); a cold pressor test (CPT) and oral glucose ingestion (GLUC).Results:  During a cold pressor test plasma noradrenaline (NA) and mean arterial pressure (MAP) increased significantly, compared with baseline (Ps < 0.01), whereas the movement thresholds were unchanged (Ps >> 0.05). After GLUC plasma NA and MAP increased significantly, compared with baseline (Ps < 0.05). The movement threshold into flexion decreased (P = 0.022), whereas into extension there was no change (P = 0.28). The most prominent increase of plasma NA corresponded with a reduced movement detection threshold, suggesting increased muscle spindle sensitivity.Conclusion: The present findings contradict previous reports from animal studies and the hypothesis that sympathetic nerve activity reduces proprioceptive acuity.
Remission maintenance by tioguanine in chronic active Crohn's disease
Authors: Herrlinger K. R. , Deibert P. , Schwab M. , Kreisel W. , Fischer C. , Fellermann K. , Stange E. F. 
Published: June 2003

SummaryBackground: Tioguanine may offer an alternative for immunosuppression in chronic active Crohn's disease. Recently, we have shown that tioguanine is effective in inducing rapid remission.Aim: To evaluate the role of tioguanine in the maintenance of remission in chronic active Crohn's disease.Methods: A follow‐up study was performed to investigate the long‐term efficacy and safety of and tolerance to tioguanine in chronic active Crohn's disease. Sixteen patients who had successfully received 6‐tioguanine for remission induction were enrolled. The reasons for immunosuppressive therapy were steroid dependence (n = 10), steroid refractoriness (n = 6) and intolerance (n = 6) or refractoriness (n = 1) to azathioprine. After remission induction therapy for 6 months, patients were treated for another 6 months with a daily dose of 20–40 mg tioguanine. Primary outcomes were remission (Crohn's disease activity index < 150) and complete steroid reduction in steroid‐dependent patients at 12 months. Laboratory controls of white blood count and liver enzymes, as well as erythrocyte tioguanine nucleotide levels, were performed regularly.Results: After 12 months of treatment, 14 of 16 (88%) patients were in remission, and 12 of these were completely free of systemic steroids. Adverse events during maintenance therapy included photosensitivity (one patient), minor viral infections (one), headache (four) and mild alopecia (one). One patient developed elevated liver enzymes, splenomegaly and thrombocytopenia, indicative of nodular regenerative hyperplasia of the liver.Conclusions: In responders to tioguanine, the drug appears to be very effective in maintaining remission of chronic active Crohn's disease. Unfortunately, long‐term hepatotoxicity seems to be an unpredictable and potentially severe adverse drug reaction. Therefore, to date, tioguanine cannot be recommended for general use outside clinical trials.
Conscious sedation with propofol in elderly patients: a prospective evaluation
Authors: Heuss L. T. , Schnieper P. , Drewe J. , Pflimlin E. , Beglinger C. 
Published: June 2003

SummaryAim: To characterize the safety of endoscopic procedures and propofol use as administered by nurses in a cohort of elderly patients.Methods: During 19 months all endoscopy patients > 70 years were eligible for this prospective observational study. Patients were assigned to group A (70–85 years) or group B (> 85 years). Records from all patients < 70 years treated during the same period served as controls. Specially trained nurses administered the propofol and monitored for complications (decrease in the peripheral oxygen saturation, mean arterial pressure or heart rate).Results: There were 1435 endoscopic procedures in group A and 351 in group B. There was no procedure or sedation‐related mortality, nor a significantly greater need for emergency intervention than in the control group. Two patients required short mask ventilation but recovered without sequelae. Compared with younger patients, there was a significant increase in risk for a short oxygen desaturation < 90% and a decrease in oxygen saturation > 5%. Arterial hypotension occurred significantly more often in the control group than among the aged patients.Conclusions: This present study documents that gastrointestinal endoscopic procedures are safe and well tolerated even in the very elderly. Nurse‐administered propofol is a safe and reasonable sedation method in these patients.