bluuebunny/crossref_metadata_2025 huggingface dataset:
In vitro activity of Triclisia patens and some bisbenzylisoquinoline alkaloids against eishmania donovani and Trypanosoma brucei brucei
Authors: Camacho Maria del Rayo , Phillipson J. David , Croft Simon L. , Rock Peter , Marshall Sarah J. , Schiff Paul L.
Published: August 2002

In the search for antiprotozoal compounds from natural sources, Triclisia patens displayed activity against L. donovani promastigotes (IC50 = 1.5 μg/mL) and T. b. brucei blood stream trypomastigote forms (IC50 = 31.25 μg/mL). In addition, a total of 20 bisbenzylisoquinoline alkaloids were screened for antileishmanial and antitrypanosomal activity in vitro. Fangchinoline (IC50 = 0.39 μM) was found to be as active as the standard pentamidine against Leishmania donovani promastigotes. Phaeanthine was three‐fold more active (IC50 = 2.41 μM; 1.5 μg/mL) than the standard drug Pentostam against L. donovani amastigotes, but at this concentration was toxic to murine macrophages. In contrast, cocsoline (IC50 = 12.3 μM; 6.76 μg/mL) was as active as Pentostam, and was not toxic to macrophages at this concentration. Thalisopidine showed the strongest activity (IC50 = 1.14 μM) against Trypanosoma brucei brucei blood stream form trypomastigotes, but was less active than pentamidine. Copyright © 2002 John Wiley & Sons, Ltd.
Scavenger activity of Allium psekemense B. Fedtsch
Authors: Štajner D. , Milić‐DeMarino M. , Čanadanović‐Bruner J. , Popović M.
Published: August 2002

In the present study the antioxidative properties of the bulbs, leaves and stalks of Allium psekemense B. Fedtsch were investigated. The activities of antioxidant enzymes (superoxide dismutase, catalase, peroxidase, glutathione peroxidase), quantities of malonyldialdehyde, superoxide and hydroxyl radicals and reduced glutathione and also the content of total flavonoids, chlorophylls a and b, carotenoids, vitamin C and soluble proteins were determined. The results indicate that extracts from all plant organs exhibited antioxidant activity. The highest antioxidant activity was observed in the leaves. Furthermore, the ESR signal of DMPO‐OH radical adducts in the presence of the leaf phosphate buffer (pH 7) extract was reduced by 54.3%. Copyright © 2002 John Wiley & Sons, Ltd.
Effect of  Ginkgo biloba extract on β‐adrenergic receptors in different rat brain regions
Authors: Hadjiivanova Ch. I. , Petkov V. V.
Published: August 2002

The effect of oral administration of Ginkgo biloba extract at a dose of 90 mg/kg for 7 consecutive days on rat brain β‐adrenergic receptors in the frontal cortex, hippocampus, striatum and hypothalamus was studied. Ginkgo biloba treatment induced a significant decrease in the density (Bmax) of β‐adrenoreceptors in the frontal cortex and hippocampus. It has been suggested that modulation of the β‐adrenergic system is implicated in the favourable effects of Ginkgo biloba extracts on learning and memory. Copyright © 2002 John Wiley & Sons, Ltd.
Jasmine absolute (Jasminum grandiflora L.) and its mode of action on guinea‐pig ileum in vitro
Authors: Lis‐Balchin M. , Hart S. , Wan Hang Lo B.
Published: August 2002

Jasmine (Jasminum grandiflorum L.) is used in aromatherapy as a holistic treatment for apathy, hysteria, uterine disorders and childbirth, muscle relaxation and coughs. Its stimulant nature, on inhalation, has been shown both in animals and man. Jasmine has a spasmolytic activity on guinea‐pig ileum and rat uterus in vitro. The mechanism of action of the spasmolytic activity, studied in vitro using a guinea‐pig ileum smooth muscle preparation, was postsynaptic and not atropine‐like. The spasmolytic effect of jasmine absolute was most likely to be mediated through cAMP, and not through cGMP. The mode of action in vitro resembled that of geranium, lavender and peppermint oils. The contradictory effect in vitro and in vivo is probably due to the solely physiological effects of jasmine absolute in vitro (producing a relaxation) compared with that in vivo, where it has a strong psychological input, producing a stimulant effect in man and enhanced movement in animals. Copyright © 2002 John Wiley & Sons, Ltd.
In vitro anti‐hepatoma activity of fifteen natural medicines from Canada
Authors: Lin Liang‐Tzung , Liu Li‐Teh , Chiang Lien‐Chai , Lin Chun‐Ching
Published: August 2002

Fifteen crude drugs, Stellaria media Cyrill. (Caryophyllaceae), Calendula officinalis L. (Compositae), Achillea millefolium L. (Compositae), Verbascum thapsus L. (Scrophulariaceae), Plantago major L. (Plantaginaceae), Borago officinalis L. (Boraginaceae), Satureja hortensis L. (Labiatae), Coptis groenlandica Salisb. (Ranunculaceae), Cassia angustifolia Vahl. (Leguminosae), Origanum majorana L. (Labiatae), Centella asiatica L. (Umbelliferae), Caulophyllum thalictroides Mich. (Berberidaceae), Picea rubens Sargent. (Pinaceae), Rhamnus purshiana D.C. (Rhamnaceae) and Hibiscus sabdariffa L. (Malvaceae), which have been used as folk medicine in Canada, were evaluated for their anti‐hepatoma activity on five human liver‐cancer cell lines, i.e. HepG2/C3A, SK‐HEP‐1, HA22T/VGH, Hep3B and PLC/PRF/5. The samples were examined by in vitro evaluation for their cytotoxicity. The results showed that the effects of crude drugs on hepatitis B virus genome‐containing cell lines were different from those against non hepatitis B virus genome‐containing cell lines. C. groenlandica was observed to be the most effective against the growth of all five cell lines and its chemotherapeutic values will be of interest for further studies. Copyright © 2002 John Wiley & Sons, Ltd.
Aloe arborescens extract inhibits TPA‐induced ear oedema, putrescine increase and tumour promotion in mouse skin
Authors: Shimpo Kan , Ida Chikako , Chihara Takeshi , Beppu Hidehiko , Kaneko Takaaki , Kuzuya Hiroshi
Published: August 2002

The ethyl acetate extract of the acetone‐soluble Aloe arborescens fraction was found to inhibit 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA)‐induced ear oedema, putrescine increase and tumour promotion in mouse skin. Chromatographic analyses of this extract revealed that phenolic compounds such as aloenin, barbaloin and isobarbaloin could be useful as cancer chemopreventive agents against tumour promotion. Copyright © 2002 John Wiley & Sons, Ltd.
Antimycobacterial physalins from Physalis angulata L. (Solanaceae)
Authors: Januário A. H. , Filho E. Rodrigues , Pietro R. C. L. R. , Kashima S. , Sato D. N. , França S. C.
Published: August 2002

Crude extracts and fractions from aerial parts of Physalis angulata have been bioassayed for antimycobacterial activity. Fraction A1‐29‐12 containing physalins B, F and D exhibited a minimum inhibitory concentration value (MIC) against Mycobacterium tuberculosis H37Rv strain of 32 μg/mL. Purified physalin B and physalin D were also tested showing MIC values against Mycobacterium tuberculosis H37Rv strain of >128 μg/mL and 32 μg/mL respectively, suggesting that physalin D plays a relevant role in the antimycobacterial activity displayed. Structural elucidation of both physalins D and B was based on detailed 13C and 1H NMR spectral analysis with the aid of 2D‐correlation spectroscopy (1H‐1H, COSY, HSQC and HMBC). The assignment of the 13C chemical shift for physalin D is reported here for the first time. Copyright © 2002 John Wiley & Sons, Ltd.
Extract of Yi Zhi Fang improves learning and memory behaviours of mice and its possible mechanisms
Authors: Shan Shao‐jie , Xu Qiu‐ping , Shoyama Yukihiro
Published: August 2002

The effects of Yi Zhi Fang extract (YZF) on learning and memory performances were investigated in mice using passive avoidance tasks. Oral administration of YZF improved learning and memory disorders induced by chemicals in both normal and senile mice.

The acetylcholine (Ach) concentration, the muscarinic Ach receptors (M‐R) and the monoamine oxidase B (MAO‐B) activities were analysed by a radioimmunoassay, a radioligand receptor binding assay and UV spectrophotometry, respectively, using senile decapitated mice. The oral administration of YZF to the senile mice increased the M‐R concentration, while the concentration of Ach and the activity of MAO‐B decreased in senile mice brains. From these results it is evident that YZF promotes the function of the central cholinergic system and inhibits the activity of MAO‐B in mice brains resulting in an enhancement of learning and memory. Copyright © 2002 John Wiley & Sons, Ltd.
Evaluation of the antimicrobial potential of medicinal plants from the Ivory Coast
Authors: Atindehou K. Kamanzi , Koné M. , Terreaux C. , Traore D. , Hostettmann K. , Dosso M.
Published: August 2002

A total of 148 crude ethanol extracts from 115 plant species were tested in vitro against Gram‐negative strains (Escherichia coli, Pseudomonas aeruginosa) and the Gram‐positive Staphylococcus aureus and Enterococcus faecalis. Moreover, they were submitted to antifungal assays against Candida albicans and Cladosporium cucumerinum, a human and a plant pathogenic microorganism, respectively, known to be good indicators of antifungal activity. No activity was detected against the Gram‐negative bacteria, while 14.8% and 10.8% of the extracts showed Gram‐positive bactericidal or bacteriostatic effects on S. aureus and E. faecalis, respectively. An antifungal activity was observed with 15 extracts (10.1%). Two species were particularly active against the fungi: Dioscorea minutiflora and Erythrina vogelii. The young tubers of D. minutiflora contain metabolites with a specific effect on fungi and were not active against the bacteria. On the other hand, E. vogelii was highly effective against the Gram‐positive bacteria and the fungi. Copyright © 2002 John Wiley & Sons, Ltd.
Anxiolytic and anticonvulsive activity of Sesbania grandiflora leaves in experimental animals
Authors: Kasture Veena S. , Deshmukh V. K. , Chopde C. T.
Published: August 2002

Various parts of Sesbania grandiflora have been used in the Indian system of medicine, in particular, the leaves of S. grandiflora are used in Ayurveda for the treatment of epileptic fits. In the present study we have evaluated the anticonvulsive activity of S. grandiflora leaves using a variety of animal models of convulsions. Bioassay guided separation was also carried out to identify the fraction possessing anticonvulsant activity. The benzene:ethyl acetate fraction (BE) of the acetone soluble part of a petroleum ether extract significantly delayed the onset of convulsions in pentylenetetrazol (PTZ) and strychnine (STR)‐ induced seizures in mice and reduced the duration of tonic hindleg extension in the maximum electroconvulsive shock (MES) induced seizures in mice. The BE contained a triterpene as a major component. In addition, the BE also inhibited electrically induced kindled seizures in mice and lithium‐pilocarpine‐induced status epilepticus in rats. It prolonged the duration of sleep induced by pentobarbital and antagonized the effect of D‐amphetamine. Mice treated with BE preferred to remain in the open arm of the elevated plus maze indicating anxiolytic activity. The BE raised the brain contents of gamma‐aminobutyric acid and serotonin. Thus the triterpene containing fraction of S. grandiflora exhibits a wide spectrum of anticonvulsant profile and anxiolytic activity. Copyright © 2002 John Wiley & Sons, Ltd.
DFT study of electronic structure of saccharin, thiosaccharin, and their respective ions: Effects of metal coordination on thiosaccharinate electronic structure
Authors: Branda M. M. , Castellani N. J. , Tarulli S. H. , Quinzani O. V. , Baran E. J. , Contreras R. H.
Published: August 2002

A rationalization of the conspicuous different abilities of saccharin and thiosaccharin to form coordination compounds with the first series of transition metal elements and to interact with heavy metal cations is sought. Their electronic molecular structures as well as those of their respective ions are compared performing natural bond orbitals (NBO) analyses of the four species. Upon deprotonation, the negative charge at the N atom in saccharin is almost constant while it decreases in thiosaccharin and the negative charge at the monocoordinated chalcogen atom is notably more increased in the latter than in the former. Apparently, the negative charge reorganization makes difficult the coordination of thiosaccharin with the first series of transition metal elements and favors its experimentally observed interaction with heavy metal cations such as cadmium, lead, mercury, silver, and thallium. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Density functional complete study of hydrogen bonding between the water molecule and the hydroxyl radical (H2O · HO)
Authors: Zhou Zhengyu , Qu Yuhui , Fu Aiping , Du Benni , He Faxin , Gao Hongwei
Published: August 2002

The hydrogen bonding complexes formed between the H2O and OH radical have been completely investigated for the first time in this study using density functional theory (DFT). A larger basis set 6‐311++G(2d,2p) has been employed in conjunction with a hybrid density functional method, namely, UB3LYP/6‐311++G(2d,2p). The two degenerate components of the OH radical 2Π ground electronic state give rise to independent states upon interaction with the water molecule, with hydrogen bonding occurring between the oxygen atom of H2O and the hydrogen atom of the OH radical. Another hydrogen bond occurs between one of the H atoms of H2O and the O atom of the OH radical. The extensive calculation reveals that there is still more hydrogen bonding form found first in this investigation, in which two or three hydrogen bonds occur at the same time. The optimized geometry parameter and interaction energy for various isomers at the present level of theory was estimated. The infrared (IR) spectrum frequencies, IR intensities, and vibrational frequency shifts are reported. The estimates of the H2O · OH complex's vibrational modes and predicted IR spectra for these structures are also made. It should be noted that a total of 10 stationary points have been confirmed to be genuine minima and transition states on the potential energy hypersurface of the H2O · HO system. Among them, four genuine minima were located. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Computing upper and lower bounds using Monte Carlo methods
Authors: Alexander S. A. , Coldwell R. L.
Published: August 2002

We computed lower bounds for some ground and excited states of the helium atom using variational Monte Carlo and the Weinstein, Temple, and Stevenson formulas. For these systems, the Temple and Stevenson bounds are approximately the same and have similar standard deviations. The Weinstein bounds are much further from the actual energies and have much larger standard deviations. We also investigated the reliability of these lower bound formulas when nonorthogonal wave functions are used. The Temple formula has been shown to produce an accurate lower bound even under such circumstances, while the Weinstein and Stevenson formulas are shown to yield incorrect results. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Role of electronic structure of ruthenium polypyridyl dyes in the photoconversion efficiency of dye‐sensitized solar cells: Semiempirical investigation
Authors: Srikanth K. , Marathe V. R. , Mishra Manoj K.
Published: August 2002

ZINDO/S calculations on cis‐Ru(4,4′‐dicarboxy‐2,2′‐bipyridine)2(X)2 and cis‐Ru(5,5′‐dicarboxy‐2,2′‐bipyridine)2(X)2 complexes where X = Cl−, CN−, and NCS− reveal that the highest occupied molecular orbital (HOMO) of these complexes has a large amplitude on both the nonchromophoric ligand X and the central ruthenium atom. The lowest‐energy metal to ligand charge transfer (MLCT) transition in these complexes involves electron transfer from ruthenium as well as the halide/pseudohalide ligand to the polypyridyl ligand. The contribution of the halide/pseudohalide ligand(X) to the HOMO affects the total amount of charge transferred to the polypyridyl ligand and hence the photoconversion efficiency. The virtual orbitals involved in the second MLCT transition in 4,4′‐dicarboxy‐2,2′‐bipyridine complexes have higher electron density on the COOH group compared to the lowest unoccupied molecular orbital and hence a stronger electronic coupling with the TiO2 surface and higher injection efficiency at shorter wavelengths. In comparison, the virtual orbitals involved in the second MLCT transition in 5,5′‐dicarboxy‐2,2′‐bipyridine complexes have lesser electron density on the COOH group, leading to a weaker electronic coupling with the TiO2 surface and therefore lower efficiency for electron injection at shorter wavelengths for these complexes. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Space hybrids
Authors: Rees D. , Hall G. G.
Published: August 2002

The theory of defining localized functions as simultaneous eigenfunctions of commuting matrices representing the variables x, y, and z is developed further to include r, the radial variable. The appropriate complete basis set for use when the weight function in the scalar product is an exponential is described. Hybrid functions that are each strongly localized around a center are defined as eigenfunctions and can be used to describe the electron density of an atom. The hybrid centers lie at the vertices of regular polyhedra centered on the nucleus. The hybrids have the important property of vanishing at the centers of all the other hybrids. Two simple examples are given to illustrate the theory and the methods of calculation. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
FTIR study of the electronic metal–support interactions on platinum dispersed on silica modified with titania
Authors: Hoffmann Helena S. , Staudt Paula B. , Costa Tania M. H. , Moro Celso C. , Benvenutti Edilson V.
Published: August 2002

Infrared spectroscopy, using carbon monoxide as probe molecule, was utilized to detect the electronic metal–support interactions on platinum dispersed on silica modified with different titania amounts. The spectral features produced by the electronic metal–support effects were observed only for the materials that present a high titania content and they are related to the crystal titania lattice. Copyright © 2002 John Wiley & Sons, Ltd.
Ultrathin SiO2 on Si II. Issues in quantification of the oxide thickness
Authors: Seah M. P. , Spencer S. J.
Published: August 2002

An analysis is made of various quantification issues concerning the analysis of ultrathin layers of SiO2 on (100) and (111) polished Si surfaces. For analysis of the oxide thickness, a simple equation is generally used involving two parameters; the attenuation length of photoelectrons in the oxide and the ratio, Ro, of the intensities of the Si 2p peak from bulk thermal SiO2 and from pure Si. An analysis of previously reported measurements of the attenuation length gives an average value of only 6% less than the theoretical value. However, careful measurements of Ro, via two routes, indicate consistently that a value of 0.88 ± 0.03 should be used rather than the calculated value of 0.53 ± 0.05. This difference may arise through systematic uncertainties in the values for the relevant inelastic mean free paths, the silicon dioxide density and the shake‐up contributions. Previously reported experimental values of Ro range from 0.67 to 0.87. Uncertainties also arise from intensity variations caused by the crystal structure of the substrate. These are mapped and a position ‘A’ is found where further work is best conducted. For the (100) surface, A is 34° from the surface normal in an azimuth midway at 22.5° between the [010] and [011] azimuths. For the (111) surface at A is 25.5° from the surface normal in the [101] azimuth. Data for much of the present work are for the (100) surface at an angle of emission of 27° at position ‘B’ at 28.5° from the surface normal in the [110] azimuth, which is equivalently good but may degrade for spectrometers with high angular resolution. If the same equation is used for calculating the thickness, position B leads to a calculated thickness that is 4% less than that measured for an average orientation, whereas data acquired for normal emission lead to a value 18% lower, and those measured at A are 2% higher. Measurements of the carbonaceous contamination confirm earlier conclusions that the contamination is better described using data for an average polymer than for glassy carbon. © Crown copyright 2002. Published by John Wiley & Sons, Ltd.
Characterization of molecularly imprinted composite membranes using an atomic force microscope
Authors: Hilal Nidal , Kochkodan Victor , Al‐Khatib Laila , Busca Gerald
Published: August 2002

Atomic force microscopy (AFM) has been used to investigate the surface structure of molecularly imprinted polyethersulphone (PES) membranes and to quantify pore size and surface roughness. Molecularly imprinted polymeric (MIP) membranes were developed using photoinitiated copolymerization of 2‐hydroxyethyl methacrylate as functional monomer and trimethylopropane trimethacrylate as crosslinker in the presence of adenosine 3′ : 5″‐cyclic monophosphate as template, followed by deposition of a MIP layer on the surface of (PES) microfiltration membranes. Atomic force microscopy images clearly indicate that a consistent increase in the degree of modification leads to a systematic decrease in pore size and an increase in surface roughness. These results show a good correlation with the filtration data of cAMP solutions. Thus, it was shown that direct AFM quantification of key parameters of imprinted membrane structure provide useful guidelines for the development of novel MIP composite membranes. Copyright © 2002 John Wiley & Sons, Ltd.
Thin films of Sr2FeMoO6 grown by pulsed laser deposition: preparation and characterization
Authors: Santiso J. , Figueras A. , Fraxedas J.
Published: August 2002

We report the first in situ XPS analysis of thin epitaxial films of the ferromagnetic double perovskite Sr2FeMoO6, which have been prepared by pulsed laser deposition on (100) SrTiO3 substrates under different oxygen pressures. The films consist mainly of the c‐axis‐oriented SFMO phase over a wide range of oxygen pressure (10−8–10−4 mbar) as determined by ex situ x‐ray diffraction measurements. However, different secondary phases are observed, depending on the preparation conditions. When obtained in ultrahigh vacuum conditions (10−8 mbar) the films show the presence of metallic Fe, whereas when prepared under pure oxygen gas flow (pressures above 10−6 mbar ) the Fe3O4 phase is observed. The in situ XPS analysis suggests the formation of the SrFeO3 phase in addition to SFMO, whereas the SrMoO4 phase is formed at oxygen pressures above 10−4 mbar. Copyright © 2002 John Wiley & Sons, Ltd.
The state of metal surfaces after blasting treatment Part I: Technical aluminium
Authors: Possart Wulff , Bockenheimer Clemens , Valeske Bernd
Published: August 2002

The aluminium–magnesium alloy EN‐AW 5754 is studied with SEM, energy‐dispersive x‐ray imaging (EDX), AES and XPS after treatment by chemical etching and blasting with glass beads or alumina grit. Blasting proves to change more than the surface profile. The freshly treated surfaces are fully covered with a carbon contamination of characteristic oxygen content ‘etch ≪ glass ≪ grit’ and average thickness ‘grit ≪ glass ≪ etch < 10 nm’. Beneath the carbon, an oxide mix is found as a continuous layer on the Al matrix. The oxide Na2O is transferred from both blast materials whereas CaO is observed after glass bead treatment only. Etching almost removes Mg but blasting retains traces of MgO. On the etched surface, the oxide layer (average thickness: glass ≪ etch ≪ grit < 10 nm) is Al2O3. Just after blasting with glass or alumina Al2O2.9 and Al2O1.3, respectively, are detected. After glass blasting, these Al atoms continue to oxidize whereas the incomplete Al oxide is almost stable after alumina blasting. These findings show that blasting produces particular chemical states that rule the interaction between the aluminium alloy and another material such as a coating or adhesive. Copyright © 2002 John Wiley & Sons, Ltd.
Room‐temperature oxidation of Fe(100), Fe(100)–3.5 wt.% MoN and segregated MoN: a mathematical analysis
Authors: Conradie R. , Roos W. D. , Swart H. C.
Published: August 2002

The room‐temperature oxidation of Fe(100), Fe(100)–3.5 wt.% MoN and a segregated MoN layer were compared with each other by using Auger electron spectroscopy. The linear least‐squares method was applied successfully to the low‐energy Fe AES peaks to obtain the fraction of metal and oxide as a function of oxygen exposure time. The backscattering term is, however, a function of the oxide coverage and an illogical decrease in the oxide thickness at higher exposures were measured. The high‐energy Auger peak‐to‐peak heights of Fe were also used to calculated the oxide thickness at different exposure times and these oxide thickness values were used to calculate the backscattering term for the different oxides as a function of exposure time. The backscattering term for the segregated MoN layer on the Fe(100)–3.5 wt.%MoN specimen is a combination of the backscattering from MoN, the iron oxide and the substrate. The profile indicates how important the change in the backscattering term may be for accurate surface concentration calculations. The backscattering terms for the Fe(100) and Fe(100)−3.5 wt.% MoN decrease exponentially with an increase in the oxygen exposure, which is in direct correlation with the logarithmic growth law of the oxides on the samples. Copyright © 2002 John Wiley & Sons, Ltd.
Comparison of source functions obtained by using QUASES and partial intensity analysis for inelastic background correction: KLL Auger spectra of 3d transition elements Cu and Ni
Authors: Kövér L. , Tougaard S. , Werner W. S. M. , Cserny I.
Published: August 2002

Correction of photoelectron and Auger spectra excited from solids for the effect of electron scattering is a key problem in quantitative surface analytical applications of XPS and AES. Based on analysis of the spectral shape of the background caused by scattering of the signal electrons, powerful methods have been developed recently and applied successfully for obtaining the ‘source functions’ (i.e. the background‐corrected spectra) as well as the in‐depth concentration profile from the measured spectra.

The QUASES analysis has been proposed as a general tool for quantification in XPS, probing depths up to ∼10 inelastic electron mean free paths (λ) using Tougaard's ‘universal’ cross‐section for inelastic scattering and the λ(E) values recommended by Powell and Jablonski. Effects of elastic scattering and surface excitations are neglected with this approach and intrinsic excitations are considered a part of the source function.

In the partial intensity approach, the observed spectrum can be decomposed into its constituent parts, i.e. the source function as well as contributions due to intrinsic bulk losses and surface extrinsic losses. This is achieved for an arbitrary emission mechanism. In particular, elastic scattering and different scattering mechanisms at different depths can be accounted for simply and consistently.

Both methods have been applied for background correction of KLL Auger spectra of the 3d transition metals Cu and Ni excited by photons from metallic thin films vacuum‐evaporated onto Si substrates. The respective source functions obtained are very similar, especially in the case of thinner films, indicating that elastic scattering and surface effects play only a minor role in influencing the spectral shape at these high energies. A detailed analysis of the differences is given, focusing on the contributions from intrinsic excitations. Copyright © 2002 John Wiley & Sons, Ltd.
Surface and electrochemical study of DBSA‐doped polypyrrole films grown on stainless steel
Authors: Prissanaroon W. , Brack N. , Pigram P. J. , Liesegang J. , Cardwell T. J.
Published: August 2002

Electrically conducting polypyrrole films doped with dodecylbenzenesulphonic acid (PPy–DBSA) have been electrochemically polymerized on stainless steel. The surface and electrochemical properties of the films were investigated by a combination of cyclic voltammetry (CV), scanning electron microscopy (SEM) and x‐ray photoelectron spectroscopy (XPS). The CV results showed an irreversible reaction of electropolymerization. All PPy–DBSA films had a nodular or cauliflower‐like surface morphology. The grain size was dependent on the growth current density and the growth time. The ratio of incorporated DBSA anions to pyrrole repeat units in the films was ∼1 : 2. The doping level, calculated from the positive charge accumulated in the polymer chain (at.% ratio (N+ + N2+)/Ntotal), varied as a function of the growth current density and the growth time. The maximum doping level occurred at a growth current density of 0.5 mA cm−2, consistent with an oxidation peak of the pyrrole monomer observed by CV. The interfacial layer between the polymer and substrate was also studied. A sulphur‐rich layer was observed, indicating the presence of a thin layer of DBSA at the interface. In addition, iron was detected on the metal side of the film as a result of its dissolution from the stainless‐steel electrode during the electropolymerization process. These results have implications for the use of polypyrrole films as environmentally friendly corrosion mitigants. Copyright © 2002 John Wiley & Sons, Ltd.
Multivariate survival analysis with doubly‐censored data: application to the assessment of Accutane treatment for fibrodysplasia ossificans progressiva
Authors: Jones Geoffrey , Rocke David M.
Published: August 2002

Fibrodysplasia ossificans progressiva is a rare genetic disorder in which the joints of patients become disabled by the formation of heterotopic bone. Data are available on the status of 11 joints of each of 21 patients before, during and after treatment with Accutane. These are compared with data obtained by questionnaire from 40 untreated patients to determine the efficacy of the treatment. Both left‐ and right‐censoring are present in each group, which, together with the multivariate nature of the data and the time‐dependent treatment covariate, makes analysis difficult. We consider two alternative parametric models for incorporating within‐subject dependence: a marginal model and a frailty model. Both analyses suggest that Accutane treatment is effective. We discuss and illustrate the differences between the two approaches. We also discuss the extent to which the conclusions are compromised by the observational nature of the study. Copyright © 2002 John Wiley & Sons, Ltd.
Bias in risk estimation: application to Down's syndrome screening
Authors: Williams K. L. , Nix A. B. J.
Published: August 2002

In this paper we consider the bias associated with parametric estimation of a univariate or bivariate Gaussian density, and also the induced bias when these Gaussian densities are used to determine a likelihood ratio. Algebraic approximations are derived that accurately predict the relative biases obtained, verification being achieved by a simulation exercise. The expressions confirm that when estimating a univariate Gaussian density there are four Z‐scores for which there is zero bias and that relative bias increases rapidly beyond two standard deviations from the mean. The results are then extended to determine approximate confidence intervals for both the true density and the likelihood ratio. A simulation exercise confirms that the derived 95 per cent confidence intervals have coverage that ranges from 94 to 97 per cent. The results are applied to a Down's syndrome screening programme where 95 per cent confidence intervals are established for a woman's posterior odds of carrying a Down's foetus. It is shown that patients with similar posterior odds can give rise to confidence intervals for their true posterior odds that have very different widths, thus emphasizing that not all risks are of equal quality. Copyright © 2002 John Wiley & Sons, Ltd.
Minimax two‐stage‐designs with applications to tissue banking case‐control studies
Authors: Shuster Jonathan , Link Michael , Camitta Bruce , Pullen Jeanette , Behm Fredrick
Published: August 2002

‘Tissue banks’ are created, at least in part, to help medical scientists learn about disease biology on the basis of samples provided by patients on treatment protocols that were competed years earlier.The bank inventory consists of precious non‐renewable patient material (such as frozen diagnostic blood or bone marrow), which can be linked to both clinical data and long term follow‐up information. Case‐control studies, where cases represent clinical failures and controls clinical successes, are ideal for rapidly learning if a laboratory marker might have prognostic significance. While group sequential (multi‐stage) methods are widely used in clinical trials, they have rarely been applied in case‐control studies. Further, unlike clinical trials where safety and efficiency may actually be in conflict, case‐control studies can focus on efficiency. Hence, minimizing the expected sample size is a desirable goal in such a setting. Since the true effect size is never known, and since no prior distribution can be postulated for the effect size, we have opted for the minimax solution. A strategy is developed to determine amongst all two‐stage designs with given type I and type II errors, the one for which the maximum expected sample size is minimized. The user is provided with simple tables, whereby one can determine everything necessary to conduct the study from the corresponding calculation for a single‐stage design. A matched pair example is given where the suggested design can be modified, to obtain a superior ‘two‐plus’ stage design. The basic idea is to conduct the first stage as planned, but use the estimate of variance to redesign the study, without using the estimate of effect size in the redesign. Copyright © 2002 John Wiley & Sons, Ltd.
Likelihood methods for measuring statistical evidence
Authors: Blume Jeffrey D.
Published: August 2002

Focused on interpreting data as statistical evidence, the evidential paradigm uses likelihood ratios to measure the strength of statistical evidence. Under this paradigm, re‐examination of accumulating evidence is encouraged because (i) the likelihood ratio, unlike ap‐value, is unaffected by the number of examinations and (ii) the probability of observing strong misleading evidence is naturally low, even for study designs that re‐examine the data with each new observation. Further, the controllable probabilities of observing misleading and weak evidence provide assurance that the study design is reliable without affecting the strength of statistical evidence in the data. This paper illustrates the ideas and methods associated with using likelihood ratios to measure statistical evidence. It contains a comprehensive introduction to the evidential paradigm, including an overview of how to quantify the probability of observing misleading evidence for various study designs. The University Group Diabetes Program (UGDP), a classic and still controversial multi‐centred clinical trial, is used as an illustrative example. Some of the original UGDP results, and subsequent re‐analyses, are presented for comparison purposes. Copyright © 2002 John Wiley & Sons, Ltd.
Inflation of type I error rate in two statistical tests for the detection of publication bias in meta‐analyses with binary outcomes
Authors: Schwarzer Guido , Antes Gerd , Schumacher Martin
Published: August 2002

The use of meta‐analysis to combine results of several trials is still increasing in the medical field. The validity of a meta‐analysis may be affected by various sources of bias (for example, publication bias, language bias). Therefore, an analysis of bias should be an integral part of any systematic review. Statistical tests and graphical methods have been developed for this purpose. In this paper, two statistical tests for the detection of bias in meta‐analysis were investigated in a simulation study. Binary outcome data, which are very common in medical applications, were considered and relative effect measures (odds ratios, relative risk) were used for pooling. Sample sizes were generated according to findings in a survey of eight German medical journals. Simulation results indicate an inflation of type I error rates for both tests when the data are sparse. Results get worse with increasing treatment effect and number of trials combined. Valid statistical tests for the detection of bias in meta‐analysis with sparse data need to be developed. Copyright © 2002 John Wiley & Sons, Ltd.
Rethinking Rouse and Daellenbach's rethinking: isolating vs. testing for sources of sustainable competitive advantage
Authors: Levitas Edward , Chi Tailan
Published: August 2002

In a recent paper, Rouse and Daellenbach (1999) provide a five‐step methodological approach which they feel will cure alleged inadequacies in empirical resource‐based research. We suggest, however, that their methodology can provide only a useful aid for expanding our understanding of potential sustainable competitive advantages but will not allow researchers to effectively verify those hypothesized advantages. Specifically, we argue that Rouse and Daellenbach's methodology is plagued by three major shortcomings: (1) it confuses the important distinction between knowing‐how and knowing‐what; (2) it fails to recognize the importance of observable variables in verifying the sources of sustainable competitive advantage; and (3) it calls for sampling on the dependent variable. Copyright © 2002 John Wiley & Sons, Ltd.
More thinking on research methods for the resource‐based perspective
Authors: Rouse Michael J. , Daellenbach Urs S.
Published: August 2002

We re‐examine the benefits of using a broader set of research methods to address key questions associated with the resource‐based view (RBV) of the firm. In responding to Levitas and Chi, we consider how research inside organizations can complement and augment research relying on secondary data. Copyright © 2002 John Wiley & Sons, Ltd.
Competitive forces and strategic choice decisions: an experimental investigation in the United States and Japan
Authors: Song Michael , Calantone Roger J. , Di Benedetto C. Anthony
Published: August 2002

Managers operate in a complex, uncertain environment and tend to form simplified models in order to cope with this environment and make competitive strategic decisions (i.e., cost‐leadership, differentiation, or focus). In this study, we use an experimental design to examine the strategic choice decision‐making process in firms located in the United States and Japan. We develop several main‐effect propositions regarding managerial selection of competitive strategies, depending on the competitive forces (buyer power, threat of substitutes, threat of new firm entry, and high intensity of rivalry) they are facing. We propose a main effect due to country of origin: Japanese managers prefer a cost‐leadership strategy more than American managers do. We also propose several interaction effects regarding cross‐national differences in strategy selection between Japanese and U.S. managers. To test our propositions, we collected experimental data from 316 U.S. executives and 459 Japanese executives. We assessed relative impacts of the competitive forces on strategic decision‐making using a multilevel regression analysis. The research findings indicated that high buyer power and high substitution threat were associated with a preference for cost‐leadership strategies, and Japanese managers were significantly more likely to prefer a cost‐leadership strategy than U.S. managers. We also found that, under conditions of high buyer power, U.S. managers were less likely than Japanese managers to enter a market with a differentiation or focus strategy. We found little support for other interaction hypotheses, suggesting points of similarity between U.S. and Japanese managers. We conclude with a discussion of theoretical and managerial implications of our results. Copyright © 2002 John Wiley & Sons, Ltd.
Autonomy and dependence of international cooperative ventures: an exploration of the strategic performance of U.S. ventures in Mexico
Authors: Robins James A. , Tallman Stephen , Fladmoe‐Lindquist Karin
Published: August 2002

Researchers have begun to view international cooperative ventures as complex, multiparty organizations in which foreign and local firms and the venture itself all have distinctive roles. This approach has important implications for the venture strategies of foreign firms in emerging economies. This study explores relationships between the resource contributions of parent firms and U.S. managers' assessment of venture performance in a sample of established U.S.–Mexican ventures. The research suggests that mature cooperative ventures are expected to achieve autonomy from parent firms in key areas at the same time that certain forms of strategic dependency also are important to success. Copyright © 2002 John Wiley & Sons, Ltd.
Contract, cooperation, and performance in international joint ventures
Authors: Luo Yadong
Published: August 2002

This study examines how contract, cooperation, and performance are associated with one another within international joint ventures (IJVs). We argue that contract and cooperation are not substitutes but complements in relation to IJV performance. An IJV contract provides an institutional framework guiding the course of cooperation, while cooperation overcomes the adaptive limits of contracts. Our analysis of 293 IJVs in a dynamic market demonstrates that previous cooperation bolsters contractual adaptability, which in turn nurtures current cooperation between the same partners. We find that contract completeness and cooperation drive IJV performance both independently and interactively. When contracts are more complete, cooperation contributes more to performance. Contract and cooperation differ in their quadratic effects such that the contribution of contract completeness to performance declines as completeness increases but the contribution of cooperation remains linear. Copyright © 2002 John Wiley & Sons, Ltd.
Value creation and destruction in cross‐border acquisitions: an empirical analysis of foreign acquisitions of U.S. firms
Authors: Seth Anju , Song Kean P. , Pettit R. Richardson
Published: August 2002

We conduct an investigation of the sources of gains and losses in cross‐border acquisitions in light of different motives for undertaking these transactions: synergy‐seeking, managerialism and hubris. We find that the data are consistent with the expectation that multiple sources of value creation exist in synergistic cross‐border acquisitions: asset sharing, reverse internalization of valuable intangible assets, and financial diversification. Gains accrue to bidder firm shareholders only for the least fungible of these sources of gains, i.e., reverse internalization. For value‐destroying acquisitions that are expected to be driven by managerialism, we find that the data are consistent with only one of the sources of value destruction that we examine, i.e., risk reduction. In these acquisitions, the evidence also suggests that the relative size of the target to the bidder mitigates the negative effects of risk reduction. Our results underscore the importance of considering the implications of alternative behavioral assumptions in empirical strategy content research. Copyright © 2002 John Wiley & Sons, Ltd.
PLEIADES: An Internet‐based parallel/distributed system
Authors: Koulopoulos D. , Papoutsis K. , Goulas G. , Housos E.
Published: August 2002

The use of LAN‐based clusters of computers for computational purposes has been in use for several years with significant success and acceptability. The introduction of the Internet infrastructure as the interconnection medium of the cluster allows for additional flexibility and transparency of such systems. PLEIADES is an Internet‐based parallel/distributed system whose purpose is to allow users to use distant computational resources in order to form virtual clusters. In addition, PLEIADES can be used as a computational infrastructure service provider for applications in need of computational resources. PLEIADES uses a tiered architecture with particular emphasis on the existence of a middle tier, whose task is to assist in the communication between the interface and the resource management tiers. The existence of the middle tier allows for the creation of an open system that is able to easily integrate with new resource management platforms and tools. Since the use of a mature resource management system for parallel/distributed computing was a prerequisite of the PLEIADES architecture, the Condor resource management environment was used. The design and implementation characteristics of PLEIADES together with some experimental uses of the system are also presented. Copyright © 2002 John Wiley & Sons, Ltd.
Automatic form generation
Authors: Mamrak Sandra A. , Pole Sheetal
Published: August 2002

The Acuity project, in support of a collaborative brain‐tumor research effort, provides WWW‐based input forms implemented as Java applets for updating a WWW‐accessible database. The continuing need to develop new, but closely related, input forms motivated the design and implementation of the Acuity Form Generator (AFG), an automatic form‐generation tool. This paper documents the AFG technology. Copyright © 2002 John Wiley & Sons, Ltd.
Drawing database schemas
Authors: Di Battista Giuseppe , Didimo Walter , Patrignani Maurizio , Pizzonia Maurizio
Published: August 2002

A wide number of practical applications would benefit from automatically generated graphical representations of database schemas, in which tables are represented by boxes, and table attributes correspond to distinct stripes inside each table. Links, connecting attributes of two different tables, represent referential constraints or join relationships, and may attach arbitrarily to the left‐ or to the right‐hand side of the stripes representing the attributes. To our knowledge no drawing technique is available to automatically produce diagrams in such a strongly constrained drawing convention. In this paper we provide a polynomial time algorithm for solving this problem, and test its efficiency and effectiveness against a large test suite. Also, we describe an implementation of a system that uses such an algorithm and we study the main methodological problems we faced in developing such a technology. Copyright © 2002 John Wiley & Sons, Ltd.
CASiNO: component architecture for simulating network objects
Authors: Battou Abdella , Khan Bilal , Lee Daniel C. , Marsh Spencer , Mountcastle Sean , Talmage David
Published: August 2002

We describe the Component Architecture for Simulating Network Objects (CASiNO) useful for the implementation of communication protocol stacks and network simulators. This framework implements a rich, modular coarse‐grained dataflow architecture, with an interface to a reactor kernel that manages the application's handlers for asynchronous I/O, real timers and custom interrupts. These features enable developers to write applications that are driven by both data flow and asynchronous event delivery, while allowing them to keep these two functionalities distinct. We provide an example program and expository comments on the program to illustrate the use of the CASiNO framework. Published in 2002 by John Wiley & Sons, Ltd.