bluuebunny/crossref_metadata_2025 huggingface dataset:
Electronic structures and some physical properties of Ni3Al alloys
Authors: Rhee J. Y. , Kudryavtsev Y. V. , Kim K. W. , Lee Y. P.
Published: March 2003

Various physical properties of Ni1–xAlx alloys (x = 0.248 and 0.229) have been investigated. We observed an intense absorption feature at ∼0.8 eV in the optical conductivity spectra, which was theoretically predicted. For x = 0.229 the 0.8 eV feature exhibits a double‐peak structure and it persists up to room temperature. A theoretical calculation shows that the fine structure originates from the magnetic inhomogeneity due to the appearance of the antistructure Ni atoms and their clusters. The temperature dependencies of the magneto‐optical properties can also be ascribed to the magnetic inhomogeneity. The existence of a magnetic inhomogeneity is further confirmed by DC χ(T) measurements.
Theoretical search for magnetic half‐Heusler semiconductors
Authors: Toboła J. , Kaprzyk S. , Pecheur P.
Published: March 2003

Electronic structure and magnetic properties of half‐Heusler FeV1–xMnxSb, CoTi1–xMnxSb and RhZr1–xMnxSb for x ≤ 0.1 are studied from KKR‐CPA computations. Ordered compounds exhibit an energy gap at the Fermi level as large 0.45 eV (FeVSb), 0.95 eV (CoTiSb), and 1.14 eV (RhZrSb). Mn atoms diluted on lighter transition metal site show magnetic moments of 2.6μB, 3.2μB, and 3.8μB, respectively. KKR‐CPA calculations show that crystal defects in the half‐Heusler semiconductors may markedly change electronic states in the vicinity of the gap and also enhance local magnetic moment on Mn. In view of KKR‐CPA results coexistence of magnetism and semiconducting state in some VEC = 18 half‐Heusler alloys seems to be plausible, when some crystal defects exist.
Local magnetic moments and hyperfine fields in Fe3–xCrxAl
Authors: Go A. , Pugaczowa‐Michalska M. , Dobrzyński L. , Lipiński S.
Published: March 2003

We present the results of self‐consistent spin‐polarised TB‐LMTO band structure calculations of Fe3Al substituted by chromium. An influence of the local environment on the distribution of hyperfine magnetic fields is discussed. All the nearest neighbours atomic configurations corresponding to the observed sextets contributing to the Mössbauer spectra are analysed. Substitution of chromium atom in the nearest neighbourhood cause the strong fall of hyperfine field.
Electronic structure of the uranium monostannide USn
Authors: Szajek A.
Published: March 2003

The uranium monostannide USn crystallizes in the orthorhombic ThIn‐type structure (Pbcm space group) in which the uranium and tin atoms each occupy three crystallographic positions. The electronic structure of USn compound has been studied using spin‐polarized tight binding version of the linear muffin‐tin orbital method in the atomic sphere approximation (TB LMTO ASA). The calculations showed that all three types of uranium atoms are magnetically ordered and their moments depend on local environments.
Theoretical study of the low‐lying electronic states of the molecular ion KRb+
Authors: Korek M. , Younes G. , Allouche A. R.
Published: March 2003

The potential energy curves of the molecular ion KRb+ have been investigated for the 60 lowest molecular states of symmetry 2Σ+, 2Π, 2Δ, and Ω = 1/2, 3/2, and 5/2. Using an ab initio method, the calculation has been done in a one active electron approach based on nonempirical pseudopotentials with core valence effects taken into account through parameterized l‐dependent polarization potentials. Using the canonicals functions approach a rovibrational study is done by calculating the eigenvalues Ev, the rotational constants Bv, the centrifugal distortion constants Dv (up to 135 vibrational levels), and the spectroscopic constants ωe and Be for the five electronic states (1)2Σ+, (3)2Σ+, (1)2Π, (1)Ω = 1/2, and (1)Ω = 3/2. No comparison of these values with other results is yet possible because they are given here for the first time. Extensive tables of energy values of Ev, Bv, and Dv are displayed at http://hplasim2.univ‐lyon1.fr/allouche. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Density functional study of indole–pyrrole heterodimer potential energy hypersurface
Authors: Pejov Ljupčo
Published: March 2003

A density‐functional study of indole–pyrrole heterodimer potential energy hypersurface (PES) was performed. Eight stationary points were located on the B3LYP/6‐31++G(d,p) PES, three of which correspond to real minima, all of them being characterized with an NH … π type hydrogen bonding. In two of these minima (the local ones), pyrrole subunit acts as a hydrogen bond proton donor, while the global minimum corresponds to indole–H … π(‐pyrrole) arrangement. Besides the interaction and dissociation energies corrected for BSSE and the monomer relaxation energies and the relevant structural parameters,anharmonicNH and NH … π vibrational frequencies were calculated for various NH oscillators involved in this interaction from the 1‐D DFT vibrational potentials. On the basis of anharmonic vibrational frequency analysis, it was concluded that the two types of NH … π hydrogen bonded dimers (indole vs. pyrrole being a proton donor) should be distinguishable with spectroscopic methods. Various contributions to the overall anharmonic frequency shifts upon hydrogen bonding were calculated and discussed as well. The charge field perturbation (CFP) technique was employed to study the electrostatic + polarization influence of the proton accepting unit on the NH(… π) vibrational potential. The second‐order perturbation theory analysis (SOPT) of the Fock matrix (i.e., its Kohn–Sham analog) within the natural bond orbital (NBO) basis, as well as various NBO deletion analyses revealed an essentially one‐directional charge transfer (CT) of a π(CC) → σ*(NH) type in the case of all three minima. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Calculation of molecular electric and magnetic multipole moment integrals of integer and noninteger n Slater orbitals using overlap integrals
Authors: Guseinov I. I. , Mamedov B. A.
Published: March 2003

Closed formulas are established for the magnetic multipole moment integrals of integer and noninteger n Slater‐type orbitals (ISTOs and NISTOs) in terms of electric multipole moment integrals for which the analytic expressions through the overlap integrals with ISTOs and NISTOs are derived. The overlap integrals are evaluated by the use of auxiliary functions. Using the derived expressions the multipole moment integrals, and therefore the electric and magnetic properties of molecules, can be evaluated most efficiently and accurately. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Pure through‐bond state in organic molecules for analysis of the relationship between intramolecular interactions and total energy
Authors: Orimoto Yuuichi , Aoki Yuriko
Published: March 2003

Ab initio configuration interaction through‐space/bond interaction analysis was proposed for the examination of specific intramolecular interactions including the effect of electron correlations. To test the effectiveness of our method, we applied it to rotational barrier in ethane. The results of our test suggest that the insensitivity of the ethane barrier to geometric relaxations is intimately connected with the cancellation of interactions through orbital overlaps and other factors. The orbital overlaps include exchange repulsion and hyperconjugation; other factors include classic Coulomb interaction and changes in bond orbital energy. The rotational state without the barrier (pure through‐bond state) can be achieved by deleting not only the “vicinal” interactions between the CH bonds that belong to different methyl groups but also the “geminal” interactions within the methyl groups. Our mixing analysis of molecular orbitals supports the superiority of the staggered conformer by hyperconjugation. Moreover, it was demonstrated that our treatment could be applied to excited states as well as to the ground state, including electron correlation effects. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Theory of time‐dependent transport in quantum dot systems
Authors: Fransson J.
Published: March 2003

The formulation of the time‐dependent tunnel current in quantum dot (QD) systems in the (generalized) transfer Hamiltonian formalism is reconsidered, taking into account the nonorthogonality between the subsystems. Exploiting the fact that only the total charge in the system is conserved, in general, gives rise to a new formulation of the transport theory. As a result, it is shown necessary to depart from the orthodox picture, in which the current is treated as a local property of the system. A general formula for the current is derived. By expressing properties of the quantum dot in the Hubbard I approximation with the loop correction, thereby including strong correlations of the QD states, numerical results are given for various time‐dependent source‐drain voltages. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Simple and sensitive liquid chromatography/tandem mass spectrometry method for the determination of diazepam and its major metabolites in rat cerebrospinal fluid
Authors: Wang Junying , Shen Xiaolan , Fenyk‐Melody Judy , Pivnichny James V. , Tong Xinchun
Published: March 2003

Diazepam (DZP) is one of the most commonly prescribed drugs for treating status epilepticus (SE). A simple, sensitive and selective LC/MS/MS method with a wide linear calibration range was developed to quantify DZP and its major metabolites, N‐desmethyldiazepam (DMDZP), temazepam (TZP), and oxazepam (OZP), in rat cerebrospinal fluid (CSF). The method was used to simultaneously determine the concentrations of all analytes in a small sample volume (as little as 25 μL) of rat CSF. The lower limits of quantification (LLOQ) of the method are 0.04 ng/mL for DZP and 0.1 ng/mL for its metabolites. The calibration range is 0.04–200 ng/mL for DZP and 0.1–200 ng/ml for the metabolites. All intra‐ and inter‐assay coefficients of variation (%CV) and mean percent errors of the method are less than 12%. This method successfully addresses the need to determine low therapeutic drug concentrations in small physiological samples, namely rat CSF. Moreover, it can be used to investigate the distribution of the drug and its metabolites among blood plasma, brain tissue, and CSF in pharmacokinetic and pharmacodynamic studies in a variety of laboratory animals. With respect to animal experiments involving assays in CSF, this method addresses two of the three criteria of Russell and Bruch (Principles of Humane Experimental Techniques, 1959, Methuen and Co., London) for minimizing animal use, namely refinement and reduction. Copyright © 2003 John Wiley & Sons, Ltd.
Investigation by solid‐phase microextraction and gas chromatography/mass spectrometry of secondary metabolites in lichens deposited on stone monuments
Authors: De Angelis Francesco , Ceci Roberta , Quaresima Raimondo , Reale Samantha , Di Tullio Alessandra
Published: March 2003

Lichens are ubiquitous organisms formed by symbiotic associations of fungal hyphas and algae that also grow under often extreme environmental conditions. They produce secondary metabolites, the so‐called lichen substances, whose structural characterization can give an important contribution to lichen taxonomy. Lichens are also widely employed as biomonitors of atmospheric pollution; being epiphyte organisms they tend, in fact, to accumulate exogenous compounds. Moreover, it could be questioned if the environmental stress alters their secondary metabolites production. Therefore, a new strategy for the analysis of the organic substances absorbed or metabolized by lichens has been developed. This method exploits the dry solid‐phase microextraction (SPME) headspace technique coupled with gas chromatography/mass spectrometry (GC/MS). Lichens coating the stone surfaces of monuments, located in small towns between high mountains and far away from urban environments, have been investigated. In the field of cultural heritage, this study can contribute to the knowledge of the state of conservation of outdoor exposed historical monuments. Copyright © 2003 John Wiley & Sons, Ltd.
Identification of hyaluronic acid oligosaccharides by direct coupling of capillary electrophoresis with electrospray ion trap mass spectrometry
Authors: Kühn Andrea V. , Rüttinger Hans H. , Neubert Reinhard H. H. , Raith Klaus
Published: March 2003

A new method for the identification of oligosaccharides obtained by enzymatic digestion of hyaluronic acid (HA) with bacterial hyaluronidase (HA lyase, E.C. 4.2.2.1, from Streptococcus agalactiae) using online capillary electrophoresis/electrospray mass spectrometry (CE/ESI‐MS) is presented. A fused‐silica capillary coated with polyacrylamide was used with a 40 mM ammonium acetate buffer at pH 9.0 and a separation voltage of +30 kV applied to the inlet. Separation was achieved for oligosaccharides containing 4–16 monomers. The migration behavior follows the chain length of the oligomers, regardless of charge state. However, no linear relationship was found for the relation between mobility and chain length. Using an ion trap mass analyzer, complementary structural information was obtained by MS/MS and MSn experiments. Copyright © 2003 John Wiley & Sons, Ltd.
Improved detection of higher molecular weight proteins by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry on polytetrafluoroethylene surfaces
Authors: Botting Catherine H.
Published: March 2003

Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) of proteins was performed on a range of polytetrafluoroethylene (PTFE) surfaces. Sinapinic acid and α‐cyano‐4‐hydroxycinnamic acid matrices were compared and the order of application varied to identify the best combination for each surface. It is demonstrated that the use of a PTFE surface improves the intensity of signals obtained for higher molecular weight proteins. Copyright © 2003 John Wiley & Sons, Ltd.
Derivatisation for liquid chromatography/electrospray mass spectrometry: synthesis of pyridinium compounds and their amine and carboxylic acid derivatives
Authors: Barry Samantha J. , Carr Richard M. , Lane Stephen J. , Leavens William J. , Monté Soraya , Waterhouse Ian
Published: March 2003

A simple method has been developed for the pre‐column derivatisation of low molecular weight primary and secondary amines and carboxylic acids using quaternary nitrogen compounds to enhance their detection by liquid chromatography/electrospray ionisation mass spectrometry (LC/ESI‐MS). The synthesis of seven novel quaternary nitrogen reagents is described. The derivatives are designed to be relatively small molecules to avoid some of the steric hindrance problems that may be associated with larger derivatisation reagents. The compounds have amine and carboxylic acid functional groups with which to derivatise carboxylic acids and amines, respectively. Two of the compounds contain a bromine atom in order to assess the advantages of a bromine isotope pattern in the mass spectra. This acts as a simple marker for derivatisation and enables data processing by cluster analysis.

Activation of the carboxylic acid group was achieved by the use of either 1‐chloro‐4‐methylpyridinium iodide (CMPI) or the more reactive 1‐fluoro‐4‐methylpyridinium p‐toluenesulphonate (FMP).1 Using both of these active reagents, the degree of nucleophilic substitution was investigated for the derivatisation of a variety of small molecules. Whilst giving some increase in the ESI‐MS response for the derivatised compounds, the FMP itself acted as a derivatising reagent in a competing reaction. In the light of this finding, FMP was reacted with the test compounds separately and gave positive results as a derivatising reagent. Detection of the ‘pre‐charged’ derivatives of amines and carboxylic acids by LC/ESI‐MS was investigated with respect to their ESI response and chromatography. Copyright © 2003 John Wiley & Sons, Ltd.
A numerical tool to integrate biophysical diversity of a large regulated river: hydrobiogeochemical bases. The case of the Garonne River (France)
Authors: Sauvage S. , Teissier S. , Vervier P. , Améziane T. , Garabétian F. , Delmas F. , Caussade B.
Published: March 2003

This article presents the bases of a hydrobiogeochemical model of the Garonne River (southwest France) which has been developed to integrate physical and biological processes during summer low‐water periods. The physical part of this model is composed of a one‐dimensional unsteady hydrodynamic model, allowing the resolution of the Saint‐Venant equations, and a transport model which simulates downstream changes in solute concentrations. Biogeochemical processes are considered through the definition of functional compartments which make up the channel bed. These different compartments are defined both by the organisms involved in the solute transformation processes and by the physical and hydraulic characteristics of their habitat. Integration of these functional compartments within the model required investigations at different scales. The scale at which biological processes take place ranges from millimetres to metres. The scale of a reach, at which organization of the functional compartments along the river can be linked to hydrodynamic and morphological characteristics, ranges from 500 m to several kilometres. The regional scale is that at which homogeneous reaches can be integrated. A feedback between numerical results and field experiments has allowed improvements to in situ measurement to increase modelling accuracy. For example, the model allows estimation of variables, such as fluxes, that are difficult to measure in situ. The developed model can integrate various functional compartments and their biogeochemical functioning. Two application examples, focused on dissolved inorganic nitrogen, are presented in order to illustrate the numerical tool functioning: integration of equations on nitrification processes in the water body, and integration of consumption/production terms on epilithic biofilm resulting from in situ experimental mean values. The model we have developed constitutes a promising analytical tool that will be able to integrate previous and future studies. Copyright © 2002 John Wiley & Sons, Ltd.
Analysis and evaluation of dictionary learning on a handy type pen‐input interface for personal use
Authors: Kimura Yoshimasa , Odaka Kazumi , Suzuki Akira , Sano Mutsuo
Published: March 2003

We present the learning characteristics of personal dictionaries used for handy type pen‐input interfaces. The personal dictionary grows by acquiring misrecognized input patterns whenever they are generated. Personal character pattern data is collected using a handy type tablet. The correct recognition rate of the data, which consists of 756 characters with 391 different characters, is improved from 79.9% to 96.2% for data used in learning, and from 78.0% to 95.4% for unlearnt data. On the contrary, the decrease of recognition rate by this learning is 0.1% –0.2%, which is negligible. The results show that the learning yields a handy type pen‐input interface that is sufficient for practical use, moreover, this paper clarifies the learning characteristics against changesin writing condition, the number of objective categories, the number of registered patterns in the personal dictionary, and the formation process of the personal dictionary. Analysis and evaluation of the results gives useful instruction on the design of recognition systems. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(4): 34–45, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1199
A neural network model for detecting a planar surface spatially from the optical flow in area MST of the visual cortex
Authors: Kawakami Susumu , Matsuoka Masahiro , Okamoto Hiroaki , Hosogi Sinya
Published: March 2003

The psychologist Gibson found some 50 years ago that motion stereo, which is indispensable in walking or driving, is realized via the optical flow on retina caused by motion. The stereo contains detection of the direction of self movement and spatial perception of the plane (its three‐dimensional orientation and depth) composing the environment. With the development of neurophysiology, it has been found that there exist cells that detect the direction of self movement from an optical flow in area MST (medial superior temporal area) of the visual cortex, acting as the central system for motion perception. The cell that spatially perceives a plane on the basis of the optical flow has not been found, despite the psychological findings of Gibson. Neither has there been a report on such a model. This paper reports an algorithm that detects three types of plane parameter (i.e., three‐dimensional orientation of the plane, time‐to‐contact to the plane, and shortest distance to the plane) by integrating the optical flow. The time‐to‐contact and orientation are detected by using the cross‐ratio transformation and polar transformation. The shortest distance and orientation are detected by using the small‐circle transformation. On the basis of these proposed algorithms and a previously reported neural network model that detects local image motion in area MT of the visual cortex (Vision Research 1996, 1999), a neural network from retina to area MST through area MT is modeled, which detects the three parameters of a plane. The neural network model (composed of 0.16 × 108 cells and 4.6 × 108 connections among these) is constructed on a computer, and it is shown that the time‐to‐contact and orientation are correctly detected. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(4): 46–59, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1200
Earthquake Sensor
Authors: Yanada T. , Furukawa H. , Ichida S. , Takubo K. , Shimizu Y. , Koganemaru K. , Suzuki T.
Published: March 2003

A new concept earthquake sensor was developed utilizing spectral intensity (SI) as a measurement value. The acceleration sensing part and signal conditioning part are all integrated in one body as a transducer. A real‐timeSIcalculation algorithm was newly developed and proved by actual simulated earthquake waveforms with a three‐axis exciter bench. A liquefaction judgment algorithm was also developed based on acceleration signals and integrated into theSIsensor. Thus, the first all‐in‐oneSIsensor with liquefaction judgment was realized. With this sensor, a new earthquake disaster prevention system for gas supply, Supreme, was developed and introduced into operation around the area of Tokyo Bay, Japan.

First online publication: April 8, 2002.
Summary of ISO/TC 201 Standard XII. ISO 17973:2002—Surface chemical analysis—Medium‐resolution Auger electron spectrometers—Calibration of energy scales for elemental analysis
Authors: Seah M. P.
Published: March 2003

This International Standard specifies a method for calibrating the kinetic energy scale of Auger electron spectrometers with an uncertainty of 3 eV for general analytical use for identifying elements at surfaces. It is suitable for instruments used in either the direct mode or the differential mode where the resolution is equal to or less than 0.5% and the modulation amplitude for the differential mode, if used, is 2 eV peak to peak. The spectrometer shall be equipped with an inert gas ion gun or other method for sample cleaning and with an electron gun capable of operating at 4 keV or higher beam energy. This International Standard further specifies a calibration schedule. Crown Copyright © 2003. Published by John Wiley & Sons, Ltd.
Static SIMS analysis of carbonate on basic alkali‐bearing surfaces
Authors: Shaw A. D. , Cortez M. M. , Gianotto A. K. , Appelhans A. D. , Olson J. E. , Karahan C. , Avci R. , Groenewold G. S.
Published: March 2003

Carbonate is a somewhat enigmatic anion in static secondary ion mass spectrometry (SIMS) because abundant ions containing intact CO32− are not detected when analyzing alkaline‐earth carbonate minerals common to the geochemical environment. In contrast, carbonate can be observed as an adduct ion when it is bound with alkali cations. In this study, carbonate was detected as the adduct Na2CO3·Na+ in the spectra of sodium carbonate, bicarbonate, hydroxide, oxalate, formate and nitrite and to a lesser extent nitrate. The appearance of the adduct Na2CO3·Na+ on hydroxide, oxalate, formate and nitrite surfaces was interpreted in terms of these basic surfaces fixing CO2 from the ambient atmosphere. The low abundance of Na2CO3·Na+ in the static SIMS spectrum of sodium nitrate, compared with a significantly higher abundance in salts having stronger conjugate bases, suggested that the basicity of the conjugate anions correlated with aggressive CO2 fixation; however, the appearance of Na2CO3·Na+ could not be explained simply in terms of solution basicity constants. The oxide molecular ion Na2O+ and adducts NaOH·Na+ and Na2O·Na+ also constituted part of the carbonate spectral signature, and were observed in spectra from all the salts studied. In addition to the carbonate and oxide ions, a low‐abundance oxalate ion series was observed that had the general formula Na2−xHxC2O4·Na+, where 0 < x < 2. Oxalate adsorption from the laboratory atmosphere was demonstrated but the oxalate ion series also was likely to be formed from reductive coupling occurring during the static SIMS bombardment event. The remarkable spectral similarity observed when comparing the sodium salts indicated that their surfaces shared common chemical speciation and that the chemistry of the surfaces was very different from the bulk of the particle. Copyright © 2003 John Wiley & Sons, Ltd.
The use of regression models for medians when observed outcomes may be modified by interventions
Authors: White Ian R. , Koupilova Ilona , Carpenter James
Published: March 2003

Some outcomes used in epidemiological studies and clinical trials are prone to modification by interventions, for example, individuals with high blood pressure are likely to receive antihypertensive medication. Often the scientific interest is in the relationship of covariates (exposures or randomized treatment) to the outcomes that would have been observed in the absence of intervention. We compare three approaches to the analysis of such data: ignoring the intervention; excluding individuals who receive the intervention, and assuming that individuals who receive the intervention have underlying outcomes above the median. The latter approach requires comparison of median outcomes between groups. In many situations it is plausible that neither the probability of intervention nor the effect of intervention depend on the covariates. In this case we show that analysis of medians is unbiased in general, that the other approaches are biased towards the null but that ignoring the intervention typically has the greatest power for detecting an effect. In other situations, ignoring the intervention and excluding individuals who receive the intervention may be biased towards or away from the null, and we recommend analysis of medians. We illustrate practical analysis of medians in a study of the association between adult blood pressure and birth weight. Adjustment for confounders is performed by median regression. We show that the significance levels are comparable to those derived from logistic regression. We also discuss the effect of grouping of blood pressure and the need for bootstrap standard errors. Copyright © 2003 John Wiley & Sons, Ltd.
Identifying effective and/or safe doses by stepwise confidence intervals for ratios
Authors: Bretz Frank , Hothorn Ludwig A. , Hsu Jason C.
Published: March 2003

Typical randomized clinical dose‐finding studies consist of the comparison of several doses of a drug versus a placebo. Interest lies in estimating relevant doses among those under investigation for efficacy and safety variables, such as the minimum effective dose or the maximum safe dose (or estimating both doses simultaneously). Step‐down procedures have been proposed for comparing the standardized differences of the dose groups against placebo. In this paper we consider the ratio of population means and propose stepwise confidence intervals for these ratios. These confidence intervals do not require multiplicity adjustments and yield the same decisions as the associated test procedures. In addition, several power concepts are investigated within the present framework. The results allow sample size determination in the design phase of a study for the probability of estimating correctly the dose of interest. Auxiliary results of a numerical study show the range of application of these methods. Copyright © 2003 John Wiley & Sons, Ltd.
A score test for establishing non‐inferiority with respect to short‐term survival in two‐sample comparisons with identical proportions of long‐term survivors
Authors: Broët P. , Tubert‐Bitter P. , De Rycke Y. , Moreau T.
Published: March 2003

In recent years randomized trials designed to establish non‐inferiority of a new treatment as compared to a standard one have been more widely used. Two‐sample statistics have been proposed for this equivalence testing problem. However, they are not suited to situations where a long‐term survivor fraction is expected. In this paper we propose a score test designed for establishing non‐inferiority for the new treatment as compared to the standard one while assuming identical long‐term survivor rates. Simulations results show that the proposed statistic has satisfactory size and power as long as certain restricting conditions are verified. A breast cancer trial is analysed as an example. Copyright © 2003 John Wiley & Sons, Ltd.
Issues in designing flexible trials
Authors: Posch Martin , Bauer Peter , Brannath Werner
Published: March 2003

We outline the general framework of adaptive combination tests and discuss their relationship to flexible group sequential designs. An important field of applications is sample size reassessment. We discuss reassessment rules based on conditional power arguments using either the observed or the prefixed effect size. These rules tend to lead to large expected sample sizes for small actual effects. However, the application of a maximal bound for the second stage sample size leads to more favourable properties. Additionally, we consider an optimized reassessment rule in terms of expected sample sizes. Since the adaptive design does not use the classical test statistics for some types of sample size reassessments, the adaptive test may reject the null hypothesis while the classical one‐sample test does not. We characterize sample size reassessment rules, where such inconsistencies are avoided. Finally, the extension of flexibility to the number of stages is explored. In the first interim analysis a second interim analysis is only planned if the chance to achieve a decision there is high. This leads to savings in the average number of interim analysis performed, without paying a noticeable price in terms of expected sample size. Copyright © 2003 John Wiley & Sons, Ltd.
Blinded sample size reassessment in non‐inferiority and equivalence trials
Authors: Friede Tim , Kieser Meinhard
Published: March 2003

Even in situations where the design and conduct of clinical trials is highly standardized, there may be a considerable between‐study variation in the observed variability of the primary outcome variable. As a consequence, performing a study in a fixed sample size design implies a considerable risk of resulting in a too high or too low sample size. This difficulty can be alleviated by applying a design with internal pilot study. After a provisional sample size calculation in the planning stage, a portion of the planned sample is recruited and the sample size is recalculated on the basis of the observed variability. To comply with the requirement of some regulatory guidelines only blinded data should be used for the reassessment procedure. Furthermore, the effect on the type I error rate should be quantified. The current literature presents analytical results on the actual level in the t‐test situation only for superiority trials. In these situations, blinded sample size recalculation does not lead to an inflation of the type I error rate. We extended the methodology to non‐inferiority and equivalence trials with normally distributed outcome variable and hypotheses formulated in terms of the ratio and difference of means. Surprisingly, in contrast to the case of testing superiority, we observed actual type I error rates above the nominal level. The extent of inflation depends on the required sample size, the sample size of the internal pilot study, and the standardized equivalence or non‐inferiority margin. It turned out that the elevation of the significance level is negligible for most practical situations. Nevertheless, the consequences of sample size reassessment have to be discussed case by case and regulatory concerns with respect to the actual size of the procedure cannot generally be refuted by referring to the fact that only blinded data were used. Copyright © 2003 John Wiley & Sons, Ltd.
A critical systems intervention to improve the implementation of a district health system in KwaZulu–Natal
Authors: Luckett Sidney , Grossenbacher Kaspar
Published: March 2003

This paper reports on a critical systems inquiry into the complexities of the implementation of a District Health System in the KwaZulu–Natal province of post‐Apartheid South Africa. The inquiry process, which was ‘governed’ by Checkland's Soft Systems Methodology (SSM) and followed the four‐phase learning cycle developed by Kolb, produced ‘conceptual models’ which enabled participant stakeholders to gain fresh perspectives on the context and, in so doing, to get the implementation process ‘unstuck’. At the theoretical/methodological level the paper contributes to the growing literature on the combination of systems methods by illustrating how conceptual models of purposeful human activity, a method intrinsic to SSM, were constructed from the participatory use of Concept Maps and Sign‐graph Diagrams. We also reflect on the interrelationship between methodology/method combination and two other aspects of the intervention that we considered to be important for maintaining the ‘systemicity’ of the intervention, viz., the inquiry context and boundary critique. Copyright © 2003 John Wiley & Sons, Ltd.
Attitude stabilization of a rotating spacecraft with flexible elements and a magnetohydrodynamic control system
Authors: Rabinovich Boris , Grishin Alexey
Published: March 2003

Rotating spacecraft with flexible spike antennas located along their rotation axis can be seriously affected by instability problems. The Auroral Probe of the INTERBALL Project is a typical example of such an object. It is shown that magnetohydrodynamic (MHD) elements may be effectively applied for control of the spacecraft. In particular, by using MHD elements it is possible to stabilize the rotation of a spacecraft without reducing its angular velocity. It is important that the MHD control system does not have hinges and does not need any special fuel storage. Copyright © 2003 John Wiley & Sons, Ltd.
Robust active control for uncertain structural systems with acceleration sensors
Authors: Wang Sheng‐Guo
Published: March 2003

Natural hazards such as earthquakes and strong wind events place large forces on tall, slender structures and on long‐span bridges that inherit numerous uncertainties due to model errors, stress calculations, material properties, and load environments. Thus, a robust feedback control for structural systems is needed. This paper develops a robust active control approach for uncertain structural systems with acceleration sensors and white noise. The approach is based on a robust state feedback control, with the robust α‐degree relative stability, robust H∞ δ‐degree disturbance rejection and robust H2 optimality, and a modified Kalman filter, with α0‐degree relative' stability. The uncertainties considered include structural ones in the system and control input matrices and multiplicative nonstructural ones in the disturbance input matrices. Special singular value decomposition (SVD) is applied to structured uncertain structures. Numerical simulations excited by the 1940 El Centro, California, earthquake data have been carried out for the proposed different robust controllers and LQG for comparison. The resulting approach to robust control may be applied to analysis and design of practical structural systems. Copyright © 2003 John Wiley & Sons, Ltd.
Rundown of a transient potassium current is attributable to changes in channel voltage dependence
Authors: Hattori Satoko , Murakami Fujio , Song Wen‐Jie
Published: March 2003

Many ionic currents undergo significant rundown during whole‐cell recording. Although rundown is an artifact associated with the recording method, studying the mechanism of rundown may lead to understanding mechanisms regulating channel functions in physiological conditions. The mechanisms for rundown, however, remain obscure for many channels. Here we have studied the mechanism for rundown of an A‐type K+ current in mouse striatal cholinergic interneurons. The interneuron expressed a prominent component of A‐type current which exhibited significant rundown during whole‐cell recording. When the current was assessed with a highly hyperpolarized prepotential (–140 mV), however, the rundown was virtually fully suppressed, suggesting its being dependent on voltage. Estimation of channel voltage dependence revealed that both activation and inactivation curves shifted towards hyperpolarized potentials during rundown. The shift was suppressed by intracellular ATP, but was affected neither by phosphatase inhibitors nor by antioxidative reagents. The gradual shift of inactivation curve towards negative potentials would make the holding potential progressively inactivate the channel, resulting in apparent loss of activity of the channels. Our results thus provide a biophysical explanation for rundown of A‐type current. Synapse 48:57–65, 2003. © 2003 Wiley‐Liss, Inc.
Strategic elements of Eastman Kodak's successful market entry in Russia
Authors: Anders Gary C. , Usachev Danila A.
Published: March 2003

Eastman Kodak is a global imaging company with extensive reach and capabilities. This article examines
Kodak's entry strategy in Russia. It explains that Kodak was able to succeed through strong personal
relations with stakeholders and decisions to invest in local production. Kodak established consumer acceptance
through open and frequent communications with their customers. This, combined with a multifaceted marketing
strategy, helped them survive the Russian financial crisis. We argue that Kodak's success has been greatly
facilitated by a set of policies that include appropriate adaptations of Western marketing and human resources
practices. © 2003 Wiley Periodicals, Inc.
The Palm Island mystery disease 20 years on: A review of research on the cyanotoxin cylindrospermopsin
Authors: Griffiths Dilwyn J. , Saker Martin L.
Published: March 2003

Poisoning of humans resulting from consumption of water affected by the toxic cyanobacterium Cylindrospermopsis raciborskii was first reported almost 20 years ago from Palm Island, northern Queensland, Australia. Since that time a great deal has been learned about this organism and cylindrospermopsin (CYN), the toxin it produces. This article reviews the information now available to us. It summarizes aspects of the chemistry of the toxin—now known to be produced by some cyanobacterial species other than C. raciborskii—and its biosynthesis and chemical synthesis in vitro, as well as its detection and measurement by chemical and biological assay. Some of the factors affecting toxin production by cultured isolates of C. raciborskii are reviewed and the conditions that cause its release from the cells described. The occurrence of CYN in water bodies and the management strategies used to minimize the harmful effects of the toxin are outlined. These include a range of water‐treatment practices now in place to remove CYN‐producing organisms and/or to neutralize the toxin together with some management procedures that have been tried, with varying degrees of success, to prevent buildup of blooms of the offending organisms. Some of the public‐health considerations arising from exposure to water supplies affected by CYN are summarized along with the risk factors and guidance values as they are currently applied. Among the more recent developments described are those that come from the application of molecular techniques for characterizing toxic and nontoxic strains and for exploring the genetic aspects of CYN production. © 2003 Wiley Periodicals, Inc. Environ Toxicol 18: 78–93, 2003
Multiplex PCR assay for Cylindrospermopsis raciborskii and cylindrospermopsin‐producing cyanobacteria
Authors: Fergusson Kim M. , Saint Christopher P.
Published: March 2003

Water bodies are routinely monitored for the presence of potentially toxic cyanobacteria; however, the methodology for confirming toxicity is currently complex and expensive. Here we describe the application of gene‐based technology to rapidly identify cylindrospermopsin‐producing cyanobacteria, specifically, Cylindrospermopsis raciborskii. A multiplex polymerase chain reaction (PCR) test was developed that simultaneously identified polyketide synthase (pks) and peptide synthetase (ps) determinants associated with cylindrospermopsin production and distinguished C. raciborskii from other cylindrospermopsin‐producing cyanobacteria of the species Anabaena bergii and Aphanizomenon ovalisporum, by targeting the rpoC1 gene. Twenty‐one C. raciborskii, 5 A. bergii, 10 Aph. ovalisporum isolates and 3 environmental samples all yielded PCR results consistent with their toxicological status, as assessed by high‐performance liquid chromatography coupled to mass spectrometry or matrix‐assisted laser desorption ionization–time‐of‐flight mass spectrometry, and C. raciborskii was always correctly identified. The PCR test is a rapid, reliable, and economical way of assessing the toxic potential of cyanobacterial blooms formed by these organisms. © 2003 Wiley Periodicals, Inc. Environ Toxicol 18: 120–125, 2003.
Successful outcome of advanced abdominal pregnancy with exclusive omental insertion
Authors: Varma R. , Mascarenhas L. , James D.
Published: March 2003

We report the case of an advanced abdominal pregnancy with exclusive omental insertion whose extrauterine location was not established until delivery by Cesarean section at 35 weeks' gestation. It is hard to believe that omental placentation alone would be sufficient to sustain a pregnancy beyond a gestation where the fetus is viable. However, this report challenges such myths and opens the debate as to what represents the minimal placental maternal viscus contact necessary to achieve fetal viability. The case also demonstrates the continuing difficulty in diagnosing this rare but serious condition despite advances in obstetric imaging, and advocates methods to avoid missing the diagnosis, which could be easily incorporated at booking and mid‐trimester scans. Apart from this case, few reports describe normal umbilical artery Doppler velocimetry in advanced abdominal pregnancy. There is a paucity of research on suitable clinical investigations prognostic for abdominal pregnancy, although this case provides further evidence for the use of Doppler as a useful surveillance tool in such cases. Finally, this case propagates the ethical and clinical controversy that exists in managing abdominal pregnancy, particularly when diagnosed late after attaining fetal viability. Expectant management may represent a feasible alternative to surgical termination provided the woman is fully informed of the attendant risks and close surveillance of the pregnancy is undertaken. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
In‐utero development of the fetal colon and rectum: sonographic evaluation
Authors: Zalel Y. , Perlitz Y. , Gamzu R. , Peleg D. , Ben‐Ami M.
Published: March 2003

Objective

To construct a normal range for the internal diameter of the fetal descending colon and rectum during gestation.

Subjects and Methods

This was a prospective, cross‐sectional study including 379 healthy pregnant women with normal singleton pregnancies at 19–40 weeks of gestation. Measurements of the fetal descending colon (maximum internal diameter) and the fetal rectum (at the level of the bladder, measuring the anteroposterior diameter), were performed by high‐resolution transabdominal sonography.

Results

Adequate bowel measurements were obtained in all 379 fetuses. The diameter of the descending colon and rectum plotted as a function of gestational age had a sigmoid curve; the curve estimation was expressed by a cubic regression equation with R2 of 0.848 and 0.831, respectively (P < 0.0001). The normal mean and the 95% prediction limits were defined.

Conclusion

The present data provide a normal range of fetal bowel (descending colon and rectum) diameters from the early second trimester of pregnancy onwards. They may allow intrauterine assessment of the development of the fetal colon and may serve as reference values in the detection of anomalies of the fetal bowel. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Comparison of uterine and spiral artery blood flow in women with unexplained and tubal infertility
Authors: Isaksson R. , Tiitinen A. , Reinikainen L. M. , Cacciatore B.
Published: March 2003

Objective

To evaluate the possible difference in uterine and spiral artery impedance to blood flow among women with unexplained and tubal infertility during spontaneous and gonadotropin‐stimulated cycles.

Methods

We prospectively compared uterine and spiral artery pulsatility index and peak systolic velocity in a longitudinal study in women with either unexplained infertility (n = 20) or tubal infertility (n = 18). Measurements of uterine and spiral artery impedance were taken on days 11–12, 16–17 and 21–23 of the spontaneous cycle and on days 1, 5 and 10 during gonadotropin stimulation. In addition, measurements were taken on the days of oocyte pick‐up and embryo transfer.

Results

A clinical pregnancy was achieved in 8/20 (40%) women with unexplained and 6/18 (33.3%) women with tubal infertility with in‐vitro fertilization treatment. There were no differences in the uterine artery pulsatility index or peak systolic velocity during the spontaneous or the in‐vitro fertilization cycle between the two groups. The impedance to blood flow in the uterine or spiral artery did not differ between women conceiving with in‐vitro fertilization‐embryo transfer and those who did not. However, the spiral artery pulsatility index on the 5th day of gonadotropin stimulation was significantly lower among women with unexplained infertility (0.96 ± 0.25) compared to women with tubal infertility (1.24 ± 0.30; P < 0.05), but on the other days of gonadotropin stimulation the spiral artery pulsatility index and peak systolic velocity were similar.

Conclusions

Impaired uterine or spiral artery blood flow is not an important factor in unexplained infertility. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.