bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liver metastases from rectal carcinoma: Disease progression during chemotherapy despite loss of arterial‐phase hypervascularity on real‐time contrast‐enhanced harmonic sonography at low acoustic energy
Authors: Piscaglia Fabio , Gaiani Stefano , Tamberi Stefano , Celli Natascia , Cecilioni Laura , Gramantieri Laura , Bolondi Luigi 
Published: August 2003

AbstractWe used a new sonographic technique, real‐time contrast‐enhanced harmonic sonography at low acoustic energy, to evaluate liver perfusion and liver metastases from colorectal cancer in a 73‐year‐old woman after chemotherapy. After 6 weeks of chemotherapy, liver metastases that had been clearly visible on conventional sonography before chemotherapy were no longer detectable on conventional sonography but were still evident on contrast‐enhanced sonography. At about 6 months after initiation of chemotherapy, the lesions were all visible again on conventional sonography and had become significantly larger, although some no longer showed contrast enhancement during the arterial phase. In this case, changes in arterial perfusion over time did not parallel the response of liver metastases to chemotherapy. © 2003 Wiley Periodicals, Inc. J Clin Ultrasound 31:387–391, 2003
Reliability of intrarenal Doppler sonographic parameters of renal artery stenosis
Authors: Demirpolat Gülgün , Özbek Süha Süreyya , Parıldar Mustafa , Oran Ismail , Memiş Ahmet 
Published: August 2003

AbstractPurposeThe goal of this study was to retrospectively evaluate false‐negative results of Doppler sonography in the diagnosis of renal artery stenosis (RAS) using intrarenal criteria.MethodsWe reviewed the clinical data and Doppler sonographic data for all patients in whom a diagnosis of RAS had been confirmed angiographically between November 1992 and January 2001. Mean intrarenal acceleration and acceleration time values—data obtained directly from color Doppler sonography—and findings of angiographic examination of the kidneys and stenotic renal arteries were evaluated.ResultsDuring the study period, 55 cases of RAS had been angiographically confirmed in 46 patients (25 male and 21 female; mean age, 50 ± 19 years [± standard deviation]). Intrarenal arterial acceleration, acceleration time values, or both were abnormal in 42 kidneys (76%) (group A) and normal in 13 kidneys (24%) (group B). The mean age ± standard deviation was significantly higher for patients in group B (60 ± 12 years) than for those in group A (47 ± 20 years) (p > 0.05). In group B, most of the stenotic lesions were atherosclerotic, and in all kidneys but 1, the lesions were located at the renal ostium or the proximal half of the artery.ConclusionsIsolated use of intrarenal Doppler sonographic criteria for RAS may lead to an unacceptably high incidence of false‐negative results in the diagnosis of this condition, especially in elderly patients. © 2003 Wiley Periodicals, Inc. J Clin Ultrasound 31:346–351, 2003
Sonographic evaluation of gallbladder volume and ejection fraction in obese women without gallstones
Authors: Sari Ramazan , Balci Mustafa Kemal , Coban Erkan , Karayalcin Umit 
Published: August 2003

AbstractPurposeObese people have an increased incidence of gallstones. Although the exact pathogenic mechanisms of gallstone development are unknown, impaired gallbladder emptying has been suggested as a possible underlying mechanism. Our aim was to investigate this possibility by evaluating gallbladder motility and related factors in obese and nonobese women without gallstones.MethodsThis study included 79 obese women and 25 nonobese healthy women. Using real‐time sonography, we evaluated fasting and postprandial (15th‐, 30th‐, 45th‐, 60th‐, 75th‐, 90th‐, 120th‐, and 150th‐minute) gallbladder volumes and ejection fractions. The smallest postprandial volume was considered the residual volume.ResultsMean (± standard deviation) fasting and residual gallbladder volumes were 43.2 ± 18.3 cm3 and 21.4 ± 11.2 cm3, respectively, in the obese women and 28.1 ± 12.3 cm3 and 7.9 ± 3.4 cm3, respectively, in the nonobese women. Maximal ejection fraction was 49 ± 19% in obese women and 63 ± 29% in nonobese women (p = 0.001). The fasting and residual volumes and the postprandial volumes at all time points were higher in obese women than in nonobese women (p < 0.001). In addition, 15th‐, 30th‐, 45th‐, 60th‐, 75th‐, and 90th‐minute postprandial ejection fractions were lower in obese women than in nonobese women (p < 0.001). Positive correlations were found between fasting gallbladder volume and body mass index and body fat weight and between residual volume and body mass index, waist circumference, body fat percentage, and body fat weight (p < 0.05 for all comparisons).ConclusionsOur results show that fasting and postprandial gallbladder volumes are higher and that postprandial gallbladder motility is lower in obese than in nonobese women. There are positive correlations between fasting gallbladder volume and body weight, body mass index, and body fat weight. © 2003 Wiley Periodicals, Inc. J Clin Ultrasound 31: 352–357, 2003
Studies on the autocatalyzed oxidation of amino acids by peroxomonosulfate
Authors: Kannan R. Sayee , Ramachandran M. S. 
Published: August 2003

AbstractThe kinetics of oxidation of six α‐amino acids (AA) by peroxomonosulfate (PMS) ion at pH 4.2 and 35°C are investigated once again. The rate of disappearance of peroxomonosulfate at constant [AA] and [H+] follows the equation

equation image
The experimental results suggest that the hydroperoxide intermediate formed by the reaction between the hydrated form of aldehyde and PMS is more reactive and is responsible for the autocatalysis. The hydroperoxide reacts with the amino acid in the rate‐determining step. This observation is contrary to the earlier explanation that the autocatalysis is due to the Schiff's base from amino acid and aldehyde. The effect of H+, the structure of the aldehyde, etc. on the rate constants are discussed. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 475–483, 2003
The effect of the mixing process on reaction kinetics
Authors: Czerlinski George , Levin Richard , Ypma Tjalling 
Published: August 2003

AbstractIf the chemical rate constants of the initial reaction steps are large, any observed value of these constants may be affected by the mixing process. To investigate the effect of mixing efficiency on reaction kinetics we use two previously analyzed reaction systems, namely the glutamic aspartic aminotransferase system and the hemoglobin/O2 system. A time constant ka for the mixing process is introduced and four values for this parameter are considered, with the fastest essentially corresponding to complete mixing before any reaction can take place. The remaining three values are associated with mixing instruments, since they may be attainable in the real world. To evaluate the mixing efficiency (and conversely determine underlying ka values) from observed kinetics, mixing was combined with chemical relaxation by temperature jumps initiated at different points in time during the mixing process. Computer simulations permit the development of specific criteria to determine (in reverse) appropriate values of ka. In this respect, the aminotransferase system proved to be more revealing than the hemoglobin system. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 484–496, 2003
8‐Hydroxy‐1,3,6‐pyrene trisulfonic acid (pyranine) bleaching by 2,2′‐azobis(2‐amidinopropane) derived peroxyl radicals
Authors: Pino Eduardo , Campos Ana M. , Lissi Eduardo 
Published: August 2003

Abstract8‐Hydroxy‐1,3,6‐pyrene trisulfonic acid, trisodium salt (pyranine), readily reacts with peroxyl radicals generated in the aerobic pyrolysis of 2,2′‐azobis(2‐amidinopropane) (AAPH). The process can be followed by monitoring the decrease in pyranine absorbance (460 nm) or fluorescence (excitation: 460 nm; emission: 510 nm). The reaction follows a nearly zero‐order kinetics in pyranine (0.25–30 μM range), suggesting a very efficient trapping of peroxyl radicals. In agreement with this, the process is order one in AAPH. The bleaching process is totally prevented by Trolox (μM range), and partially prevented by Trp (mM range). The protection afforded by Trp is very little dependent upon the pyranine concentration. This result indicates that the main protective pathway is not a competitive scavenging of the peroxyl radicals. The data suggest protection due to repair of the initially produced pyranyl radicals. These radicals are also very efficient in the destruction of C‐phycocyanin bilin groups. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 525–531, 2003
Existence of solutions to an anisotropic phase‐field model
Authors: Burman Erik , Rappaz Jacques 
Published: August 2003

AbstractWe consider an anisotropic phase‐field model for the isothermal solidification of a binary alloy due to Warren–Boettinger ( Acta. Metall. Mater. 1995; 43(2):689). Existence of weak solutions is established under a certain convexity condition on the strongly non‐linear second‐order anisotropic operator and Lipschitz and boundedness assumptions for the non‐linearities. A maximum principle holds that guarantees the existence of a solution under physical assumptions on the non‐linearities. The qualitative properties of the solutions are illustrated by a numerical example. Copyright © 2003 John Wiley & Sons, Ltd.
Scaled boundary finite‐element analysis of a non‐homogeneous axisymmetric domain subjected to general loading
Authors: Doherty James P. , Deeks Andrew J. 
Published: August 2003

AbstractThe scaled boundary finite‐element method is derived for elastostatic problems involving an axisymmetric domain subjected to a general load, using a Fourier series to model the variation of displacement in the circumferential direction of the cylindrical co‐ordinate system. The method is particularly well suited to modelling unbounded problems, and the formulation allows a power‐law variation of Young's modulus with depth. The efficiency and accuracy of the method is demonstrated through a study showing the convergence of the computed solutions to analytical solutions for the vertical, horizontal, moment and torsion loading of a rigid circular footing on the surface of a homogeneous elastic half‐space. Computed solutions for the vertical and moment loading of a smooth rigid circular footing on a non‐homogeneous half‐space are compared to analytical ones, demonstrating the method's ability to accurately model a variation of Young's modulus with depth. Copyright © 2003 John Wiley & Sons, Ltd.
A new approach for calculating strain for particulate media
Authors: O'Sullivan Catherine , D. Bray Jonathan , Li Shaofan 
Published: August 2003

AbstractDiscrete element modelling is a viable alternative to conventional continuum‐based analysis for analysing problems involving localized deformations of particulate media. However, to aid in the interpretation of the results, it is useful to express the results of discrete element analyses in terms of the continuum parameters of stress and strain. A number of homogenization methods have been proposed to calculate strain in discrete systems; however, two significant limitations of these methods remain. First, none of these methods incorporate particle rotation effects satisfactorily, although significant particle rotation occurs in shear bands in both physical tests and numerical simulations of granular materials. Additionally, observations of the particle displacement fields in shear bands in granular materials indicate that the displacements within the localizations are erratic. Consequently, existing linear, local interpolation approaches produce substantial variations in the strain values calculated in adjacent elements in the region of localization, hindering clear visualization of the strain localization as it evolves. A new method of domain discretization for calculating strain is proposed. This method is capable of capturing particle rotation and employs a non‐local meshfree interpolation procedure capable of smoothing the erratic displacements in strain localizations, which better defines their evolution. The proposed method is validated for problems involving both two and three dimensions. A number of methods are compared with the proposed method and pertinent insights are made. Copyright © 2003 John Wiley & Sons, Ltd.
Age replacement policies in two time scales
Authors: Frickenstein Scott G. , Whitaker Lyn R. 
Published: August 2003

AbstractWe develop and estimate optimal age replacement policies for devices whose age is measured in two time scales. For example, the age of a jet engine can be measured in the number of flight hours and the number of landings. Under a single‐scale age replacement policy, a device is replaced at age τ or upon failure, whichever occurs first. We show that a natural generalization to two scales is to replace nonfailed devices when their usage path crosses the boundary of a two‐dimensional region M, where M is a lower set with respect to the matrix partial order. For lifetimes measured in two scales, we consider devices that age along linear usage paths. We generalize the single‐scale long‐run average cost, estimate optimal two‐scale policies, and give an example. We note that these policies are strongly consistent estimators of the true optimal policies under mild conditions, and study small‐sample behavior using simulation. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 592–613, 2003.
Exploiting self‐canceling demand point aggregation error for some planar rectilinear median location problems
Authors: Francis R.L. , Lowe T.J. , Rayco M.B. , Tamir A. 
Published: August 2003

AbstractWhen solving location problems in practice it is quite common to aggregate demand points into centroids. Solving a location problem with aggregated demand data is computationally easier, but the aggregation process introduces error. We develop theory and algorithms for certain types of centroid aggregations for rectilinear 1‐median problems. The objective is to construct an aggregation that minimizes the maximum aggregation error. We focus on row‐column aggregations, and make use of aggregation results for 1‐median problems on the line to do aggregation for 1‐median problems in the plane. The aggregations developed for the 1‐median problem are then used to construct approximate n‐median problems. We test the theory computationally on n‐median problems (n ≥ 1) using both randomly generated, as well as real, data. Every error measure we consider can be well approximated by some power function in the number of aggregate demand points. Each such function exhibits decreasing returns to scale. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 614–637, 2003.
Nonparametric estimation of some quantities of interest from renewal theory
Authors: From Steven G. , Li Linxiong 
Published: August 2003

AbstractIn this paper, confidence intervals are given for two quantities of importance related to renewal processes. For each quantity, two confidence intervals are discussed. One confidence interval is given for general, all‐purpose use. Another confidence interval is given which is easier to compute, but not of general use. The case where data are subject to right censorship is also considered. Some numerical comparisons are made. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 638–649, 2003.
Pulsed charged sprays: application to DISI engines during early injection
Authors: Shrimpton J. S. 
Published: August 2003

AbstractNumerical predictions of the temporal evolution of pulsed sprays, typical of those used in gasoline direct injection spark ignition engines are presented, with the novelty that the drops are electrically charged. The rate of spray expansion, in terms of the fraction of maximum possible spray charge for a typical engine timescale, is investigated. The engine timescale chosen is the time available between spray injection and ignition, and for a low‐speed engine operation, with injection during the intake stroke. The aim is to quantify the amount of electric charge, required to spread the spray throughout the engine cylinder, without causing excessive piston and wall impingement, prior to hypothetical ignition. It is found that experimentally realizable amounts of electric charge are sufficient to cause spray expansion throughout the engine cylinder within the timescale permitted. Also noted is a segregation of the smaller drops from their larger cousins, by virtue of the known non‐linear variation in drop charge with drop mass. Since it is known that pulsed fuel injectors producing charged sprays of insulating liquids are a reality then electric charge seems to be a viable route to control and optimize in‐cylinder mixture distribution and hence engine performance, robustness and emissions. Copyright © 2003 John Wiley & Sons, Ltd.
Determination of a kinship system using ancient DNA, mortuary practice, and historic records in an upper Canadian pioneer cemetery
Authors: Dudar J. C. , Waye J. S. , Saunders S. R. 
Published: August 2003

AbstractRecovered and amplified ancient DNA (aDNA), from a historically documented 19th century Upper Canadian pioneer cemetery produced genotypes that were used to infer a past societal kinship system. While the results from multiplex short tandem repeat (STR) amplifications showed an unreliable polymerase chain reaction (PCR) product, a single locus HUMTH01 analysis yielded reproducible data and an allelic frequency pattern not statistically different from modern populations. Mitochondrial (mt) DNA HVR II data showed that a combined cemetery database exhibited reduced haplotype diversity indicators, as well as clusters of probable maternally related burials. The chronological persistence and replacement of mtDNA clusters approximately every two generations suggests a patrilineal/patrilocal kinship structure from a virilocal burial program for the Harmony Road cemetery. Through the integration of the aDNA analysis with archaeological material culture, historic records, and other ethnohistoric sources of information, this conclusion is supported. In this study persisting patrilineally inherited surnames act as a surrogate for aDNA Y‐chromosome haplotype analysis. These results suggest that aDNA applications on aggregate skeletal collections where sparse, or no ethnological or historical documentation exists, may result in incorrect population history inferences if the presence of a kinship interment bias is not considered. Copyright © 2003 John Wiley & Sons, Ltd.
Improvement of properties of silica‐filled styrene‐butadiene rubber (SBR) compounds using acrylonitrile‐styrene‐butadiene rubber (NSBR)
Authors: Choi Sung‐Seen , Chung Kyung‐Ho , Nah Changwoon 
Published: August 2003

AbstractSince silica has strong filler–filler interactions and adsorbs polar materials, a silica‐filled rubber compound wil have poor dispersion of the filler and a poor cure characteristic. Improvement of properties of silica‐filled styrene‐butadiene rubber (SBR) compounds has been studied using emulsion SBR‐based acrylonitrile‐styrene‐butadiene rubber (NSBR). The silica dispersion is improved by adding NSBR to the compound. The bound rubber content increases with increase in the NSBR content. The scorch time and cure rate become faster as the NSBR content increases. The crosslink density also increases by increasing the NSBR content. The wear property is improved by adding the NSBR. Copyright © 2003 John Wiley & Sons, Ltd.
Preparation and characterization of epoxy‐cyanate ester interpenetrating network matrices/organoclay nanocomposites
Authors: Dinakaran K. , Alagar M. 
Published: August 2003

AbstractThe interpenetrating network matrices of epoxy and cyanate ester was made using epoxy resin and three different cyanate ester monomers namely 1,1‐bis(3‐methyl‐4‐cyanatophenyl) cyclohexane, bisphenol dicyanate and 1,3‐dicyanatobenzene and cured by using diaminodiphenylmethane. Epoxy modified with 4, 8 and 12% (by weight) of cyanate esters were made. Cyanate ester modified epoxy matrices were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and heat deflection temperature (HDT) analysis. Thermal studies indicate that the introduction of cyanate ester into epoxy resin improves the thermal degradation studies at the expense of glass transition temperature. DSC thermogram of cyanate ester modified epoxy show unimodel reaction exotherms. The matrices, in the form of castings, were characterized for their mechanical properties namely, tensile strength, flexural strength and unnotched Izod impact test as per ASTM methods. Mechanical studies indicate that the introduction of cyanate ester into epoxy resin improves the toughness and flexural strength with reduction in tensile strength. The morphology of the epoxy and cyanate ester‐epoxy systems were also studied by scanning electron microscope (SEM). The organophilic montmorillonite clay‐epoxy and cyanate ester‐epoxy nanocomposites are prepared and the formation nanocomposites are evaluated by X‐ray diffraction (XRD), dynamic mechanical analysis (DMA) and SEM. Copyright © 2003 John Wiley & Sons, Ltd.
Synthesis and characterization of metal binding pseudotripeptides
Authors: Kuenzel Sebastian , Pretzel David , Andert Janet , Beck Kirsten , Reissmann Siegmund 
Published: August 2003

AbstractMetal complexes with peptide or pseudopeptide type ligands can serve as good model compounds for a deeper understanding of enzymatic catalysis, but ligands with a high selectivity for different transition metal cations are hard to find due to the rather flexible nature of peptides. Since such ligands would be the sine qua non condition for the synthesis of heterodinuclear peptide metal complexes with catalytic activity, the search for small, affine and selective metal chelating sequences is of interest. Using four different amino acids (His, Lys, Asp, Glu) a set of 16 pseudotripeptides of the common structure Bz‐AS1‐Sar‐AS2‐NH2 has been synthesized, purified and characterized by mass spectrometry and 1H‐NMR. Their ability to form metal complexes has been investigated leading to short motifs capable of selectively binding only one or two transition metal cations with high affinity. As expected, the complexation of transition metal cations by pseudotripeptides is strongly dependent not only on the amino acid composition, but also on the sequence with regard to the stability of the resulting complexes, as well as the selectivity of the ligands towards Cu2+, Co2+, Ni2+, Zn2+ and Mn2+. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Recoupling coefficients of group SO(4) and their application to linear tetratomic molecules
Authors: Ding Shiliang , Wang Meishan , Feng Dongtai , Li Bofu , Sun Jiazhong 
Published: August 2003

AbstractThe general expressions for the recoupling coefficients of group SO(4) are obtained by employing the subgroup chains (2) and (11). When considering a special case, we give results that can be used for tetratomic molecules. Using these recoupling coefficients, the matrix elements of C and M operators that are not diagonal can be given. Within the dynamic algebra framework, an effective algebraic Hamiltonian of linear tetratomic molecules is obtained. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 293–301, 2003