bluuebunny/crossref_metadata_2025 huggingface dataset:
A trend‐surface technique for discrimination of surf‐zone morphology: rip current channels
Authors: Brander Robert W. , Cowell Peter J.
Published: August 2003

A major problem facing coastal nearshore studies is the conversion of survey data to precise two‐ and three‐dimensional representations of complex surf zone topography. In addition to inherent problems in providing accurate survey data, most signiﬁcant topographical boundaries are often delineated in a subjective manner. A trend‐surface technique is hereby presented which provides an objective, rigorous, and replicable method of identifying morphological rip system channel boundaries in the surf zone. Using an extensive ﬁeld dataset obtained over two ﬁeld experiments, including an almost complete cycle of low‐energy intermediate beach state evolution, this technique is shown to produce accurate planimetric dimensions for a range of topographic beach state morphologies. Previously absent or highly descriptive in the literature, formal morphometric deﬁnitions of geometric dimensions for rip morphologies, including rip‐channel width, relief, depth, and cross‐sectional areas, are provided. Several new aspects of rip‐current morphology are discussed from results of the approach. The approach described here is also intended to illustrate the potential for future trend‐surface applications to surf zone and other geomorphological studies. Copyright © 2003 John Wiley & Sons, Ltd.
Rock thermal data at the grain scale: applicability to granular disintegration in cold environments
Authors: Hall Kevin , André Marie‐Françoise
Published: August 2003

Consideration of the mechanisms associated with the granular disintegration of rock has been limited by available data. In most instances, both the size of the transducer and the nature of the study have negated any applicability of the resulting data to the understanding of grain‐to‐grain separation within rock. The application of microthermocouples (≤0·15 mm diameter) and high‐frequency logging (20 s intervals) at a taffoni site on southern Alexander Island and from a rock outcrop on Adelaide Island (Antarctica) provide new data pertaining to the thermal conditions, at the grain scale, of the rock surface. The results show that thermal changes (ΔT/t) can be very high, with values of 22 °C min−1 being recorded. Although available data indicate that there can be differences in frequency and magnitude of ﬂuctuations as a function of aspect, all aspects experienced some large magnitude (≥2 °C min−1) ﬂuctuations. Further, in many instances, large thermal changes in more than one direction could occur within 1 min or in subsequent minutes. These data suggest that the surface grains experience rapidly changing stress ﬁelds that may, with time, effect fatigue at the grain boundaries; albedo differences between grains and the resulting thermal variations are thought to exacerbate this. The available data failed to show any indication of water freezing (an exotherm) and thus it is suggested that microgelivation may not play as large a role in granular breakdown as is often postulated for cold regions, and that in this dry, Antarctic region thermal stress may play a signiﬁcant role. Copyright © 2003 John Wiley & Sons, Ltd.
Interchannel hydraulic geometry and hydraulic efficiency of the anastomosing Columbia River, southeastern British Columbia, Canada
Authors: Tabata Kevin K. , Hickin Edward J.
Published: August 2003

The morphodynamics of the anastomosing channel system of upper Columbia River in southeastern British Columbia, Canada, is examined using an adaptation of conventional hydraulic geometry termed ‘interchannel hydraulic geometry’. Interchannel hydraulic geometry has some of the characteristics of downstream hydraulic geometry but differs in that it describes the general bankfull channel form and hydraulics of primary and secondary channels in the anastomosing channel system. Interchannel hydraulic geometry generalizes these relationships and as such becomes a model of the geomorphology of channel division and combination. Interchannel hydraulic geometry of upper Columbia River, based on ﬁeld measurements of ﬂow velocity and channel form at 16 test sections, is described well by simple power functions:wbf= 3·24Qbf0·64;dbf= 1·04Qbf0·19;vbf= 0·30Qbf0·17. These results, with other related measurements of ﬂow resistance, imply that channel splitting leads to hydraulic inefﬁciency (higher ﬂow resistance) on the anastomosing Columbia River. Because these ﬁndings differ from those reported in studies elsewhere, we conclude that hydraulic efﬁciency does not provide a general explanation for anabranching in river channels. Copyright © 2003 John Wiley & Sons, Ltd.
Long‐term modelling of landslides for different forest management practices
Authors: Dhakal Amod S. , Sidle Roy C.
Published: August 2003

Long‐term effects of different forest management practices on landslide initiation and volume were analysed using a physically based slope stability model. The watershed‐based model calculates the effects of multiple harvesting entries on slope stability by accounting for the cumulative impacts of a prior vegetation removal on a more recent removal related to vegetation root strength and tree surcharge. Four sequential clearcuts and partial cuts with variable rotation lengths were simulated with or without leave areas and with or without understorey vegetation in a subwatershed of Carnation Creek, Vancouver Island, British Columbia. The combined inﬁnite slope and distributed hydrologic models used to calculate safety factor revealed that most of the simulated landslides were clustered within a 5 to 17 year period after initial harvesting in cases where sufﬁcient time (c. 50 years) lapsed prior to the next harvesting cycle. Partial cutting produced fewer landslides and reduced landslide volume by 1·4‐ to 1·6‐fold compared to clearcutting. Approximately the same total landslide volume was produced when 100 per cent of the site was initially clearcut compared to harvesting 20 per cent of the area in successive 10 year intervals; a similar ﬁnding was obtained for partial cutting. Vegetation leave areas were effective in reducing landsliding by 2‐ to 3‐fold. Retaining vigorous understorey vegetation also reduced landslide volume by 3·8‐ to 4·8‐fold. The combined management strategies of partial cutting, increasing rotation length, provision of leave areas, and retention of viable understorey vegetation offer the best alternative for minimizing landslide occurrence in managed forests. Copyright © 2003 John Wiley & Sons, Ltd.
An accurate and efficient finite‐difference algorithm for non‐hydrostatic free‐surface flow with application to wave propagation
Authors: Stelling G. , Zijlema M.
Published: August 2003

A numerical technique is presented for the approximation of vertical gradient of the non‐hydrostatic pressure arising in the Reynolds‐averaged Navier–Stokes equations for simulating non‐hydrostatic free‐surface flows. It is based on the Keller‐box method that take into account the effect of non‐hydrostatic pressure with a very small number of vertical grid points. As a result, the proposed technique is capable of simulating relatively short wave propagation, where both frequency dispersion and non‐linear effects play an important role, in an accurate and efficient manner. Numerical examples are provided to illustrate this; accurate wave characteristics are already achieved with only two layers. Copyright © 2003 John Wiley & Sons, Ltd.
A multigrid pseudospectral method for steady flow computation
Authors: Chou Mo‐Hong
Published: August 2003

In this work two‐dimensional steady flow problems are cast into a fixed‐point formulation, Q = F(Q). The non‐linear operator, F, is an approximate pseudospectral solver to the Navier–Stokes equations. To search the solution we employ Picard iteration together with a one‐dimensional error minimization and a random perturbation in case of getting stuck. A monotone convergence is brought out, and is greatly improved by using a multigrid strategy. The efficacy of this approach is demonstrated by computing flow between eccentric rotating cylinders, and the regularized lid‐driven cavity flow with Reynolds number up to 1000. Copyright © 2003 John Wiley & Sons, Ltd.
Family influences on dysfunctional thinking in anxious children
Authors: Bögels Susan M. , van Dongen Lieke , Muris Peter
Published: August 2003

Anxious children are found to interpret ambiguous stories in a negative way. The current study attempted to examine the possible influence of parental fear and parental interpretation bias on the maintenance of such an interpretation bias. Children varying in level of anxiety (n=25) and their parents, filled in a questionnaire to measure their own fears, and gave their interpretations concerning nine ambiguous stories, relevant for childhood ‘interactional’ anxieties: social anxiety, separation anxiety, and generalized anxiety. Then, parents were asked to talk with their children about three of the stories. After the family discussion the children had to give their final interpretations. Results indicated that parents' self‐reported fear level and interpretation bias were associated with children's interpretation bias before the family discussion. However, no evidence was found for the idea that parents maintain or enhance the interpretation bias of their children. That is, irrespective of parental fear and parental interpretation bias, children interpreted the ambiguous stories as less negative after discussing them with their parents. Copyright © 2003 John Wiley & Sons, Ltd.
An exploratory study of the kinematics of girls with Turner Syndrome in a visuo‐motor task
Authors: Smits‐Engelsman B.C.M. , Nijhuis van der Sanden M.W.G. , Duysens J.
Published: August 2003

In this paper a study is reported in which a group of children with Turner Syndrome (TS) is compared on motor performance tests and real‐time kinematic data with a control group. The objective of this study was to identify possible kinematic variables that characterize the movement patterns utilized by this group of children in achieving their optimal performance. The underlying idea is that by comparing test results and movement kinematics one might gain more insight into the movement production of children than by just looking at the test results or by just using clinical movement observation. The children performed a pen and paper task, the flower trail (one of the sub‐tests of the Movement ABC) (Henderson and Sugden, 1992), on an XY‐tablet. We explored kinematic variables, such as trajectory length, movement time, velocity and pen pressure. It was found that, although girls with TS have a severe motor deficit, they are able to draw a line accurately between two narrow boundaries just as well as the control children (no significant difference in mean number of spatial errors). However, quantitative analysis revealed that girls with TS made a large amount of deviations from the optimal path such that their trajectory length increased with more than 10% per flower trail compared to the control group children. They also made more pen lifts and more changes in velocity. The study showed that children from the two groups may reach the same basic accuracy performance level by using very different strategies. Kinematic registration of fine motor tasks holds promise in gaining more insight into how clinical groups cope with their specific motor problems. Copyright © 2003 John Wiley & Sons, Ltd.
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

We 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

Purpose

The 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.

Methods

We 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.

Results

During 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.

Conclusions

Isolated 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

Purpose

Obese 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.

Methods

This 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.

Results

Mean (± 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).

Conclusions

Our 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

The 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

If 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

8‐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

We 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

The 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

Discrete 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

We 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

When 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

In 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

Numerical 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

Recovered 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

Since 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

The 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

Metal 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

The 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
Theoretical study of the adsorption of ethylene on alkali‐exchanged zeolites
Authors: Ketrat Sombat , Limtrakul Jumras
Published: August 2003

The structures of alkali‐exchanged faujasite (X–FAU, X = Li+ or Na+ ion) and ZSM‐5 (Li–ZSM‐5) zeolites and their interactions with ethylene have been investigated by means of quantum cluster and embedded cluster approaches at the B3LYP/6‐31G(d, p) level of theory. Inclusion of the Madelung potential from the zeolite framework has a significant effect on the structure and interaction energies of the adsorption complexes and leads to differentiation of different types of zeolites (ZSM‐5 and FAU) that cannot be drawn from a typical quantum cluster model, H3SiO(X)Al(OH)2OSiH3. The Li–ZSM‐5 zeolite is predicted to have a higher Lewis acidity and thus higher ethylene adsorption energy than the Li–FAU zeolites (16.4 vs. 14.4 kcal/mol), in good agreement with the known acidity trend of these two zeolites. On the other hand, the cluster models give virtually the same adsorption energies for both zeolite complexes (8.9 vs. 9.1 kcal/mol). For the larger cation‐exchanged Na–FAU complex, the adsorption energy (11.6 kcal/mol) is predicted to be lower than that of Li–FAU zeolites, which compares well with the experimental estimate of about 9.6 kcal/mol for ethylene adsorption on a less acidic Na–X zeolite. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 333–340, 2003
Industry, corporate, and segment effects and business performance: a non‐parametric approach
Authors: Ruefli Timothy W. , Wiggins Robert R.
Published: August 2003

The literature investigating the degree to which firm performance is associated with industry or corporate factors has recently been subject to criticism on the grounds of both methodological shortcomings and incomplete interpretation of results. Our research goes beyond these critiques to raise more basic issues concerning the assumptions underlying variance decomposition, the methodology dominating the antecedent literature. Performance data and categorizations from a sample consistent with those employed in the recent literature are analyzed via a new non‐parametric methodology. Results here indicate that corporate factors were over an order of magnitude better predictors of business unit profit position than were industry factors—which were found not to have been significant predictors. Further, underlying performance relationships were seen to have shifted over time. A key implication of these results for researchers is that they provide additional evidence that managers can have a strategic influence on business performance. Copyright © 2003 John Wiley & Sons, Ltd.
Introducing QoS awareness in distributed programming: QTcl
Authors: Canonico Roberto , D'Arienzo Maurizio , Romano Simon Pietro , Ventre Giorgio
Published: August 2003

A number of distributed applications require communication services with quality of service (QoS) guarantees. Building global‐scale distributed systems with predictable properties is one of the great challenges for computer systems engineering in the new century. Work undertaken within the Internet Engineering Task Force has led to the definition of novel architectural models for the Internet with QoS support. According to these models, the network has to be appropriately configured in order to provide applications with the required performance guarantees.

In next‐generation networks, enabling applications to interact with the underlying QoS services is of primary importance. Hence, several special‐purpose application programming interfaces (APIs) have been defined to let applications negotiate QoS parameters across QoS‐capable networks. However, so far, none of these APIs are available in different operating environments. We believe that such features should be embedded in programming environments for distributed applications. In this work we present how we included QoS control features in Tcl, a programming language that has been widely adopted for the development of distributed multimedia applications. Our work has led to the implementation of QTcl, an extended Tcl interpreter that provides programmers with a new set of primitives, in full compliance with the standard SCRAPI programming interface for the RSVP protocol. QTcl in highly portable, in that it enables standard QoS negotiation to be performed in a seamless fashion on the most common operating systems. Copyright © 2003 John Wiley & Sons, Ltd.
On aspectualizing component models
Authors: Pichler Roman , Ostermann Klaus , Mezini Mira
Published: August 2003

Server‐side component models such as Enterprise JavaBeans (EJB) add powerful abstractions to the bare ‘business objects’ layer in order to support a clean separation of server‐side application logic from other concerns such as distribution, security, transaction management and persistence. An improved separation of concerns is also the main goal of aspect‐oriented programming (AOP). This paper compares the two approaches and reasons about the possibility of substituting (parts of) component models using AOP mechanisms. We conclude that AOP is a promising approach to eliminate important shortcomings of the container‐based component approach. However, our analysis of concrete aspect‐oriented languages shows that current AOP technology is not yet mature enough to supersede component models. Copyright © 2003 John Wiley & Sons, Ltd.
Effects of endogenous agonists, glycine and D‐serine, on in vivo specific binding of [11C]L‐703,717, a PET radioligand for the glycine‐binding site of NMDA receptors
Authors: Haradahira Terushi , Okauchi Takashi , Maeda Jun , Zhang Ming‐Rong , Nishikawa Toru , Konno Ryouichi , Suzuki Kazutoshi , Suhara Tetsuya
Published: August 2003

A positron‐emitter (carbon‐11) labeled antagonist for the glycine‐binding site of NMDA receptors, [11C]L‐703,717, has a unique in vivo binding characteristic, in which it preferentially binds to cerebellar‐specific NMDA receptors consisting of a GluRϵ3 subunit and eventually accumulates in rodent cerebellum under in vivo conditions, but not under in vitro conditions. In order to understand the in vivo‐specific site and subunit localization of this radioligand, we examined the effect of the endogenous glycine site agonists, glycine and D‐serine, on in vivo [11C]L‐703,717 binding. An increase in extracellular glycine concentration by treatment with a glycine transporter 1 (GlyT1)‐selective inhibitor, NFPS ethyl ester, significantly decreased the cerebellar localization of [11C]L‐703,717 in rats. D‐serine is known to be concentrated in mammalian forebrain regions. The lack of D‐serine detection in the cerebellum may be due to the fact that it has the highest enzymatic activity of D‐amino acid oxidase (DAO). It was found that the cerebellar localization of [11C]L‐703,717 is greatly diminished in mutant mice lacking DAO, in which D‐serine content in the cerebellum is drastically increased from a nondetectable level in normal mice. These studies indicate that [11C]L‐703,717 is susceptible to inhibition by glycine site agonists in its in vivo binding, and suggest that regional differences in inhibitions by endogenous agonists may be a crucial factor in the site‐ and subunit‐specific binding of this glycine‐site antagonist. Synapse 50:130–136, 2003. © 2003 Wiley‐Liss, Inc.
Lipid rafts determine efficiency of NADPH oxidase activation in neutrophils
Authors: Shao Dongmin , Segal Anthony W. , Dekker Lodewijk V.
Published: August 2003

We have investigated the contribution of lipid rafts to activation of the NADPH oxidase enzyme system in neutrophils. Membrane‐bound NADPH oxidase subunits are present in the lipid raft compartment of neutrophils. Cytosolic NADPH oxidase components are mainly absent from but are recruited to rafts upon Fcγ receptor activation. In parallel, protein kinase C isotypes are recruited to the rafts. Kinetic analysis of NADPH oxidase activation revealed that rafts determine the onset but not the maximal rate of enzyme activity. Thus lipid rafts serve to physically juxtapose the NADPH oxidase effector, protein kinase C and Fcγ receptor, resulting in efficient coupling.
The receptor for advanced glycation end‐products (RAGE) directly binds to ERK by a D‐domain‐like docking site
Authors: Ishihara Katsuya , Tsutsumi Kae , Kawane Shiho , Nakajima Motowo , Kasaoka Tatsuhiko
Published: August 2003

The receptor for advanced glycation end‐products (RAGE)‐mediated cellular activation through the mitogen‐activated protein kinase (MAPK) cascade, activation of NF‐κB and Rho family small G‐proteins, cdc42/Rac, is implicated in the pathogenesis of inflammatory disorders and tumor growth/metastasis. However, the precise molecular mechanisms for the initiation of cell signaling by RAGE remain to be elucidated. In this study, proteins which directly bind to the cytoplasmic C‐terminus of RAGE were purified from rat lung extracts using an affinity chromatography technique and identified to be extracellular signal‐regulated protein kinase‐1 and ‐2 (ERK‐1/2). Their interactions were confirmed by immunoprecipitation of ERK‐1/2 from RAGE‐expressing HT1080 cell extracts with anti‐RAGE antibody. Furthermore, the augmentation of kinase activity of RAGE‐bound ERK upon the stimulation of cells with amphoterin was demonstrated by determining the phosphorylation level of myelin basic protein, an ERK substrate. In vitro binding studies using a series of C‐terminal deletion mutants of human RAGE revealed the importance of the membrane‐proximal cytoplasmic region of RAGE for the direct ERK–RAGE interaction. This region contained a sequence similar to the D‐domain, a ERK docking site which is conserved in some ERK substrates including MAPK‐interacting kinase‐1/2, mitogen‐ and stress‐activated protein kinase‐1, and ribosomal S6 kinase. These data suggest that ERK may play a role in RAGE signaling through direct interaction with RAGE.
Structure–function correlates of Vpu, a membrane protein of HIV‐1
Authors: Montal M
Published: August 2003

Vpu, a membrane protein from human immunodeficiency virus‐1, folds into two distinct structural domains with different biological activities: a transmembrane (TM) helical domain involved in the budding of new virions from infected cells, and a cytoplasmic domain encompassing two amphipathic helices, which is implicated in CD4 degradation. The molecular mechanism by which Vpu facilitates virion budding is not clear. This activity of Vpu requires an intact TM helical domain. And it is known that oligomerization of the VPU TM domain results in the formation of sequence‐specific, cation‐selective channels. It has been shown that the channel activity of Vpu is confined to the TM domain, and that the cytoplasmic helices regulate the lifetime of the Vpu channel in the conductive state. Structure–function correlates based on the convergence of information about the channel activity of Vpu reconstituted in lipid bilayers and on its 3‐D structure in membranes by a combination of solution and solid‐state nuclear magnetic resonance spectroscopy may provide valuable insights to understand the role of Vpu in the pathogenesis of AIDS and for drug design aimed to block channel activity.
The Cbl proteins are binding partners for the Cool/Pix family of p21‐activated kinase‐binding proteins
Authors: Flanders James A , Feng Qiyu , Bagrodia Shubha , Laux Maria T , Singavarapu Avinash , Cerione Richard A
Published: August 2003

Members of the Cool protein family contain SH3, Dbl, and pleckstrin homology domains and are binding partners for the p21‐activated kinase (PAK). Using the yeast two‐hybrid screen, we identified Cbl‐b as a Cool family binding partner. We co‐immunoprecipitated endogenous Cool and Cbl‐b from a variety of breast cancer cell lines. The Cool–Cbl‐b interaction requires the SH3 domain of Cool and competes with the binding of PAK to Cool proteins. Expression of Cbl‐b effectively blocks the ability of Cool‐2 to stimulate PAK, thus providing an additional mechanism, aside from catalyzing receptor ubiquitination, by which Cbl‐b acts as a negative regulator for signaling activities requiring PAK activation.
Membrane traffic fuses with cartilage development
Authors: Sacher Michael
Published: August 2003

The ability of cells to synthesize and secrete proteins is essential for numerous cellular functions. Therefore, when mutations in one component of the secretory pathway result in a tissue‐specific defect, a unique opportunity arises to examine the molecular mechanisms at play. The recent finding that a defect in the protein sedlin, whose yeast counterpart is involved in the first step of the secretory pathway, leads to a cartilage‐specific disorder in humans raises numerous questions and interesting possibilities for understanding both the pathobiology involved and the role of membrane traffic in normal cartilage development.