bluuebunny/crossref_metadata_2025 huggingface dataset:
Mode of Action and Partial Purification of the Active Centre of exo-Poly-α-D-galacturonosidase from Selenomonas ruminantium
Authors: Heinrichová Kveta , Heinrich Július , Dzúrová Mária , Ziolecki Alexander
Published: April 2003

In the presented paper are summarized results of the study of the mode of action, dimensions and arrangement of the active centre of the exo-poly-α-D-galacturonosidase, (poly(1,4-α-D-galactosiduronate) digalacturonohydrolase, E.C. 3.2.1.82) produced by the bacteria Selenomonas ruminantium. With this aim we determined experimentally values of Michaelis constants and limiting rates for the catalytic hydrolysis of linear oligo(D-galactosiduronates) of the degree of polymeration in the range of 3 to 8, at pH 7.0 and the temperature 30 °C. We calculated molecular activities k0 and parameters k0/Km from these values. From the dependence of logk0 and logk0/Km on the degree of polymerization five subsites of the active centre were determined, with the catalytic site being situated between the second and third one. Kinetic data were used for the calculation of the affinities of the fourth and fifth subsites A4 and A5 in accordance with the theory of Hiromi. Product analysis of non-labelled oligo(D-galactosiduronates) and compounds labelled with [1-3H] at the reducing end anabled to ascertain approximately the value for the first subsite A1 of the active centre and to study the mode of action of the exo-poly-α-D-galacturonosidase from Selenomonas ruminantium.
Support Effect in Carbon Oxide(s) Hydrogenation on Cu-Cr Supported Catalysts
Authors: Rassoul Zahia , Barrault Joël , Bettahar Mohamed M.
Published: April 2003

Reducibility, adsorptive properties and catalytic properties of Cu-Cr supported on TiO2, ZnO and Al2O3 were studied in carbon oxide(s) hydrogenation. ZnO is the best retardant for the reduction of copper, stabilizing more strongly Cu+ species and retaining great amounts of H2 during the reduction of the calcined precursors. A strong support effect is observed for the CO2/H2 reaction and good correlations are established between catalytic activities, Cu+ species present in the reduced state and H2 adsorption and storage. ZnO is the most active support but not the most selective one for this reaction. The support effect is not so important for the CO/H2 reaction, but ZnO supported catalyst is again the most active and also the most selective.
A Fractal Oriented Upgrading of Reliability and Safety Knowledge of Realistic Chemical Engineering Problems
Authors: Dohnal Mirko
Published: April 2003

Reliability and safety knowledge is very sparse, Its realistic and objective application is nearly impossible. Additional knowledge is needed to increase the reasoning power of reliability and safety knowledge bases. The conventional fractal analysis has been used for the study of chaos in physical systems. Its possible role in the evaluation of reliability/safety knowledge bases is studied in this paper. The only precondition for the application of fractal analysis is an ability to distinguish between specific and general knowledge items. This enables us to detect a level of inconsistency between mostly subjective additional knowledge items and the existing knowledge bases. The fractal analysis can characterise the knowledge base as one integrated complex. However, knowledge acquisition requires "local" evaluations as well. Therefore a discriminative analysis is used. A realistic man-machine dialogue (an evaluation of the mean time between failures of control valves) supported by the fractal and/or discriminative analysis is presented
Liquid-Liquid Equilibrium in the Water-Methyl tert-Butyl Ether-Nitromethane-Ethylene Glycol System
Authors: Kubíček Vladimír , Novák Josef P. , Matouš Jaroslav
Published: April 2003

The liquid-liquid equilibrium was measured at 20 °C in the title quaternary system and in the three nitromethane-containing ternary subsystems. The data were compared with those predicted by a superposition of the Wilson and Redlich-Kister equations including the ternary parameters. The agreement between the observed and calculated data is very good both for the quaternary system and for the three ternary systems.
Synthesis and Properties of (±)- and (+)-4-MeS-3-C2H5-1,2,3-C2CoB9H10
Authors: Plešek Jaromír , Grüner Bohumír , Maloň Petr
Published: April 2003

Selective demethylation of the zwitterion 9-Me2S-7,8-C2B9H11 by sodium naphthalenide in tetrahydrofuran led to the racemic [ 9-MeS-7,8-C2B9H11]- ion, which could be partially resolved to its (-)-enantiomer via the [(-)-1-Ph-1-Me3N-CHCH3]+ salt. Complexation of the ions with Co2+ and C5H5- afforded the (±)- and (+)-4-MeS-3-C2H5-1,2,3-C2CoB9H10 cobaltacarboranes, respectively. A partially resolved (-)-9-Me2S-7,8-C2B9H11 was obtained by re-methylation of the (-)-[ 9-MeS-7,8-C2B9H11]- ion.
On the Incipient Fluidized State of Solid Particles
Authors: Hartman Miloslav , Coughlin Robert W.
Published: April 2003

A comprehensive study has been reported on all aspects of the transition of packed bed to the state of incipient fluidization (point of minimum fluidization, onset of fluidization): particle size and shape, size distribution in a batch of particles, fixed bed voidage, pressure drop through a packed bed and oneset of fluidization. A number of predictive equations have been compared that were proposed to estimate the minimum fluidization velocity. All the equations tested do not have any flow limitations and are applicable to laminar, transitional as well as to turbulent flow regime. While some equations have some foundation in theory, the other are more or less generalized correlations of experimental data amassed by different authors under various conditions. The influence of temperature and pressure on the minimum fluidization velocity has been explored with respect to the important applications such as combustion and gasification. Problems have also been discussed with transition from fixed to fluidized bed of binary and polydisperse systems.
Structure Analysis of Catechol-Like Molecular Fragments
Authors: Huml Karel , Soldán Pavel , Zimmermann Karel
Published: April 2003

A system of rigid benzene ring and two variable torsion angles ϕ(C-C-OH) in catechol-like molecular fragments was studied. A scattergam of the two torsion angles taken from the Cambridge Structural Databank is in a good agreement with the potential energy map calculated with the AMBER compatible energy minimizer ORAL. Symmetry operations and point symmetry domains used during the analysis are described in detail. Results are interpreted in accord with the catchment region theory and the structure-correlation principle.
Potential Energy Curve and Dissociation Energy for the SnCl Molecule
Authors: Rajamanickam Narayanan , Ponraj Natarajan , Ezhilarasan Ponpandian Durai , Arumugachamy Veluchamy , Fernandez Gomez Manuel , Lopez Gonzalez Juan Jesus
Published: April 2003

The potential energy curve for the electronic ground state of the SnCl molecule has been constructed by the Rydberg-Klein-Rees method in the modification by Vanderslice and collaborators. Empirical potential functions, of five parameters by Hulburt and Hirschfelder, of three parameters by Lippincott and collaborators, and that by Szoke and Baitz using the electronegativity are examined for their adequacy to represent the true curve. The five parameters by Hulburt-Hirschfelder function, U(r) = De[(1 - e-x)2 + c x3 e-2x (1 + bx)], was found to be the best fitting function and it was used for the determination of the dissociation energy. The estimated value attained for dissociation energy is 346 ± 8 kJ mol-1. For this value of dissociation energy, the estimated values for parameters and expansion coefficients are c = 0.06864, b = -0.363738, a0 = 2.759 . 103 m-1, a1 = 2.876 and a2 = 4.013, a0, a1 and a2, being the Dunham's coefficients.
The Spectrophotometric Determination of Elements with Chromazurol S in the Presence of Cetyltrimethylammonium Bromide and Triton X-100. II. Multicomponent Spectrophotometric Determination of the Sum of the Rare Earth Elements, Al, Fe and Th Using Multivariate Calibration with PLS Data Evaluation
Authors: Jančář Luděk , Preisler Jan , Sommer Lumír
Published: April 2003

A procedure was developed for the simultaneous spectrophotometric determination of the sum of the rare earth elements, Al, Fe and Th using chromazurol S in the presence of cetyltrimethylammonium bromide and Triton-100 for optimized conditions at pH 5.5 and 10.2. Multivariate calibration and the PLS procedure were employed to evaluate data for a variable number of calibration solutions and wavelengths. A new procedure was described for combination of the data of independently measured systems at both pH values. The errors in the determination of the concentration values for Al, Fe, Th and the sum of the rare earth elements in model solutions and in the concentrates of the rare earth elements were not greater than 10 rel.%.
Approximate Calculation of Fall Velocity of Spherical Particle in Generalized Newtonian Fluid in Creeping Region
Authors: Dolejš Václav
Published: April 2003

The paper gives a relation of the Rabinowitsch-Mooney type between the consistency variables τs and Ds which has been suggested, together with the force balance, for approximate calculation of the fall velocity of spherical particle in generalized Newtonian fluid. Its applicability to solutions characterized by the Ellis flow model has been experimentally proved.
Structure of 2,3,4,5-Tetra-O-acetyl-6-amino-6-deoxy-D-galactonolactam
Authors: Havlíček Jaroslav , Kefurt Karel , Hušák Michal , Novotný Jiří , Kratochvíl Bohumil
Published: April 2003

The title crystal structure was solved by direct methods and refined anisotropically to R = 0.082 for 1 612 unique observed reflections. The compound crystallizes in P 212121 space group with the lattice parameters a = 8.317(1), b = 8.412(1), c = 24.091(3) Å, V = 1 685.3(3) Å3, Z = 4.
Synthesis of Oligodeoxynucleotides Eliminating the Use of Acetonitrile
Authors: Smrt Jiří , Arnold Luboš , Svoboda Jan , Hák Roman , Rosenberg Ivan
Published: April 2003

H-Phosphonate synthesis of oligodeoxynucleotids is described in which acetonitrile is replaced by dichloromethane. This solvent is thereafter easily regenerated and reused. Practically "one solvent" procedure of oligonucleotide synthesis has been established. The preparation of 5'-O-(4,4'-dimethoxytriphenylmethyl)-N2-(N,N-dimethylaminomethylene)-2'-deoxyguanosine (Ic) and 5'-O-(4,4'-dimethoxytriphenylmethyl)-N6-(N,N-dimethylaminomethylene)-2'-deoxyadenosine (Id) is described.
Medium-Size Polarized Basis Sets Applicability for Interaction Energy Calculations: He2 and Be2 van der Waals Systems
Authors: Nowek Andrzej
Published: April 2003

Polarized bases set approach has been applied for preparation of medium-size contracted GTO basis sets starting from various standard energy-optimized and even-tempered isotropic atomic basis sets. Their usefulness for calculation of the SCF interaction energy and its components as well as dispersion energy consistently determined within the dimer basis set were studied for He2 and Be2 systems for intermediate internuclear separations. The results obtained with polarized basis sets indicate their good performance in comparison with property oriented ones.
Improved Measurement of the Kinetics of Crystallization in a Batch Experiment
Authors: Nývlt Jaroslav , Karel Miloslav
Published: April 2003

An improved method is described whereby knowledge of the supersaturation course during a run and measurement of the final product crystal size distribution yield the growth rate of crystals and the nucleation rate in a wide range of supersaturations from only a single batch experiment. The evaluation method is refined by the interpolation of experimental data for short intervals of time. The method is illustrated using potassium sulfate crystallization as an example.
An Integration of Quantitative and Qualitative Knowledge in Process Engineering
Authors: Kvapilík Martin , Dohnal Mirko
Published: April 2003

A value of a qualitative variable (derivative) can be positive, negative, or zero. Qualitative models are such models which contain qualitative variables only. Some parameters of an industrial process are measurable. Their time records are available. The main goal of this paper is to predict qualitative behaviour of all those variables which are not measured (cannot be measured) using time records of all such variables which are measured. Two case studies (damped oscillation, three reactor system) are given in details.
Glycine Sulfates and Selenates
Authors: Eysseltová Jitka , Mohyla Martin , Tomášková Marie
Published: April 2003

Solubility isotherms in the glycine-H2SO4-H2O system at 25 °C are presented. Based on these isotherms, the literature data on preparation of glycine sulfates and selenates are evaluated critically.
Polarographic Behaviour of Some Arylazotheophyllines
Authors: Ismail Mohamed I. , Iskander Madlene L.
Published: April 2003

The polarographic behaviour of a series of arylazotheophyllines was studied in aqueous alcoholic buffer media and in DMF-0.1 M LiClO4 solution. The redox study gave evidence that the azo group is electroactive in aqueous as well as non-aqueous media. A mechanism interpreting the electrode process is proposed and confirmed through the identification of the controlled potential electrolysis products, the use of a model compound and the application of Hamett's σ-E relationship. The physico-chemical characteristics of these compounds, viz. the diffusion coefficient, dissociation constant, ionization potential and electron affinity, are also included.
Synthesis of 17α-Hydroxy Steroids: B-Norepitestosterone
Authors: Kasal Alexander
Published: April 2003

The key intermediate VI was prepared by two ways: by B ring contraction of an androst-5-ene-3β,17α-diol derivative I and by configurational inversion of the 17β-hydroxy group in a B-norandrost-5-ene-3β,17β-diol derivative XII. B-Norepitestosterone (IX) and its potentional metabolite X were then prepared by standard methodology. Both these compounds appear to be inhibitors of 5α-reductase.
Novel Synthesis of 3-Spiroheterocycles-2-methylquinolin-4-one
Authors: Ahmed Abd El-Hamid N.
Published: April 2003

2-Methyl[3,1]benzoxazin-4-one (I) is easily accessible , but its chemistry has not been investigated enough. Structure similarity between I and phthalic anhydride encouraged us to investigate the reaction of I with compounds bearing active methylenes namely diethyl malonate, ethyl acetoacetate and acetylacetone in presence of zinc chloride, Thus new compounds II, III and IV were synthesized. Those compounds were used as precursors for the synthesis of various spiroheterocycles.
Small-Angle Neutron Scattering Study of Poly(oxyethylene)-block-poly(oxypropylene)-block-poly(oxyethylene) in Aqueous Solutions
Authors: Pospíšil Herman , Pleštil Josef , Tuzar Zdeněk
Published: April 2003

Solutions of a triblock copolymer, poly(oxyethylene)-block-poly(oxypropylene)-block-poly(oxyethylene) (POE-POP-POE), in deuterated water were studied by small-angle neutron scattering (SANS) in the temperature range from 20 to 45 °C. Radius of gyration, molecular weight, second virial coefficient for both unimers and micelles, critical micelle concentration and unimer concentration were determined from the scattering data. Under assumption of the spherical core/shell micellar model structural parameters were estimated. Degree of swelling of the micellar core was evaluated from the mean-square fluctuation of scattering density.
Isomorphous Substitution of Si for Al, Ga, Fe, In and B in Molecular Sieves of MFI Structure. A Quantum Chemical, Ammonia Desorption and Catalytic Activity Study of Framework Si-OH-M Acid Site Strength
Authors: Zahradník Rudolf , Hobza Pavel , Wichterlová Blanka , Čejka Jiří
Published: April 2003

A theoretical and experimental study of metallosilicates with MFI structure revealed the order Al > Ga > Fe > In > B in the acid Si-OH-M framework site strength. Ab initio calculations of the energy and geometry characteristics in a simple structural unit modelling the isomorphous substitution were carried out for Al, Ga, In and B as heteroatoms in silicates. Experimental data on toluene alkylation with ethylene and temperature-programmed desorption of ammonia allowed to distinguish the acid site strength of Al-, Fe- and In-silicates, thus, completing the acidity sequence of metallosilicates synthesized so far. Moreover, the study confirmed rather short-range effects resulting from isomorphous substitution of a heteroatom into the molecular sieve framework.
The Synthesis of Branched Poly(methyl methacrylate)
Authors: Dos Santos Claudio G. , Jenkins Aubrey D. , Walton David R. M. , Stejskal Jaroslav , Kratochvíl Pavel
Published: April 2003

The synthesis of branched poly(methyl methacrylate) is described. The method used is based on an anionic technique with initiation by enolate ions. details of product characterization are included.
Interaction between Amines and Poly(N-phenylmaleimides)
Authors: Přádný Martin , Lokaj Jan , Ševčík Stanislav
Published: April 2003

The interaction of substituted poly(N-phenylmaleimides) with low- and high-molecular-weight amines were studied. Colourless chloroform solutions of polymers, which carry electron-attracting substituents in benzene rings, turn intensively red on addition of amines in neutral or basic media depending on the nucleophilicity and accesibility of amino groups. Absorption spectra of the solutions in the visible range suggest that the formation of colour complexes consists in an interaction of free electron pairs of amines with adjacent carbonyl groups of the polyimides.
The Peroxidase Reaction of Human Methaemoglobin: Character of the Amino Acid Electrondonor and the Influence of Oxygen
Authors: Stopka Pavel , Pavlíček Zdeněk , Lhotová Jana
Published: April 2003

The chemical modification of tyrosyl residues in methaemoglobin led to the decreased peroxidase activity and thus confirmed the role of tyrosyl residues in the catalytic process. The ESR spectra of methaemoglobin modified by tetranitromethane showed on the participation of tyrosine in the generation of superoxide anion radical. After repeated catalytic cycles the rapid decreasing of superoxide anion radical content was observed. This fact indicated, that the generation generation of superoxide anion radical is connected with tyrosyl residue. The residues with high probability are the source of the second electron in the peroxidase reaction the dissolved oxygen in the reaction mixture is necessary. This oxygen is also responsible for tyrosine destruction and thus for the decreasing of peroxidase activity of methaemoglobin.
A Model of CoO Oxidation
Authors: Tkadlecová Marcela
Published: April 2003

A model of CoO oxidation was proposed which assumes the diffusion of cobalt atoms from the bulk of crystalline to its surface and the surface reaction of these atoms with surrounding oxygen. It depends on the comparison of expressions D/a20 and kxox/a0 to what extent these two processes will manifest themselves for the given temperature and oxygen mole fraction xox. The value of diffusivity D and its temperature dependence were estimated from the data in literature and the size of crystallites a0 from roentgenographic measurements. The value of rate constant of surface reaction k and its energy of activation were evaluated from experimental data for CoO oxidation.
Catalytic Oxidation of Isobutene on a Polycomponent Catalyst
Authors: Machek Jaroslav , Tichý Josef , Švachula Jiří
Published: April 2003

The catalytic gas-phase oxidation of isobutene has been studied on polycomponent Mo-Co-Ni-Bi-Fe-K oxide catalyst suitable for industrial preparation of propenal from propene. It has been found that within the temperature interval 290 - 350 °C the main oxidation products are 2-methylpropenal, acetone, 2-methylpropenoic acid, acetic acid and carbon dioxide. A modification of the mentioned catalyst by addition of a further component (W, P, Te, and Zn) showed that zinc increases the conversion of isobutene and at the same time markedly increases its selectivity for 2-methylpropenal, whereas the additions of tungsten and phosphorus decrease the conversion of isobutene with simultaneous increase of selectivity for CO2. If tert-butyl alcohol is used as the starting material instead of isobutene, then the extent of reaction is slightly decreased with simultaneous increase of selectivity for 2-methylpropenal, whereas the selectivities for the acids remain almost unchanged.
The Study of Drift in Inductively Coupled Plasma Optical Emission Spectrometry. Analysis of Silicate and Carbonate Raw Materials
Authors: Kanický Viktor
Published: April 2003

The work shows the importance of maintaining a constant temperature in a spray chamber to obtain a stable signal in the ICP spectrometry of water solutions. Simple shielding against ICP thermal radiation and forced air circulation in a plasma torch/spry chamber. The internal standard method has been used to improve signal stability. The number and composition of calibration solutions have been optimized for the detremination of the main constituents of some silicate and carbonate raw materials. An ultrasonic cleaning bath has been successfully used instead of stirring to dissolve the samples after fusion with LiBO2. Certified Czech and Slovak geological reference materials and some international standards have been used to test the accuracy. Statistical tests have proved that the method of determination complies with the requirements of technological standards.
Determination of Mercury and Copper Traces in Ultrapure Spectral Carbon by DPASV on a Gold-Fibre Microelectrode
Authors: Rievaj Miroslav , Mesároš Štefan , Bustin Dušan
Published: April 2003

A simple and sensitive method is proposed applying a gold fibre microelectrode for the DPASV determination of Hg and Cu traces in an ultrapure spectral carbon. The procedure allows simultaneous determination of both elements at the purity level lower than 1 . 10-6 wt.%. Two different sample preparation techniques -ashing in stream of oxygen, and elution with a mixture of concentrated HCl and HNO3 - were applied for releasing the metals spread in carbon matrix. Testing of the digestion techniques with synthetic Hg and Cu spiked samples proved both to be satisfactory. The proposed determination has a sensitivity high enough to verify the required highest purity level of the spectral carbon as concerns Hg and Cu traces.
Extension of Wald's first lemma to Markov processes
Authors: Moustakides George V.
Published: April 2003

Let ξ0,ξ1,ξ2,… be a homogeneous Markov process and let Sn denote the partial sum Sn = θ(ξ1) + … + θ(ξn), where θ(ξ) is a scalar nonlinearity. If N is a stopping time with 𝔼N < ∞ and the Markov process satisfies certain ergodicity properties, we then show that 𝔼SN = [limn→∞𝔼θ(ξn)]𝔼N + 𝔼ω(ξ0) − 𝔼ω(ξN). The function ω(ξ) is a well defined scalar nonlinearity directly related to θ(ξ) through a Poisson integral equation, with the characteristic that ω(ξ) becomes zero in the i.i.d. case. Consequently our result constitutes an extension to Wald's first lemma for the case of Markov processes. We also show that, when 𝔼N → ∞, the correction term is negligible as compared to 𝔼N in the sense that 𝔼ω(ξ0) − 𝔼ω(ξN) = o(𝔼N).
Asymptotic behavior of a multiplexer fed by a long-range dependent process
Authors: Liu Zhen , Nain Philippe , Towsley Don , Zhang Zhi-Li
Published: April 2003

In this paper we study the asymptotic behavior of the tail of the stationary backlog distribution in a single server queue with constant service capacity c, fed by the so-called M/G/∞ input process or Cox input process. Asymptotic lower bounds are obtained for any distribution G and asymptotic upper bounds are derived when G is a subexponential distribution. We find the bounds to be tight in some instances, e.g. when G corresponds to either the Pareto or lognormal distribution and c − ρ < 1, where ρ is the arrival rate at the buffer.
Quasistationary distributions for continuous time Markov chains when absorption is not certain
Authors: Pollett P. K.
Published: April 2003

Recently, Elmes et al. (see [2]) proposed a definition of a quasistationary distribution to accommodate absorbing Markov chains for which absorption occurs with probability less than 1. We will show that the probabilistic interpretation pertaining to cases where absorption is certain (see [13]) does not hold in the present context. We prove that the state probabilities at time t conditional on absorption taking place after t, generally depend on t. Conditions are derived under which there is no initial distribution such that the conditional state probabilities are stationary.
The fundamental matrix for a certain random walk
Authors: Taylor Howard M.
Published: April 2003

Consider the random walk {Sn} whose summands have the distribution P(X=0) = 1-(2/π), and P(X = ± n) = 2/[π(4n2−1)], for n ≥ 1. This random walk arises when a simple random walk in the integer plane is observed only at those instants at which the two coordinates are equal. We derive the fundamental matrix, or Green function, for the process on the integral [0,N] = {0,1,…,N}, and from this, an explicit formula for the mean time xk for the random walk starting from S0 = k to exit the interval. The explicit formula yields the limiting behavior of xk as N → ∞ with k fixed. For the random walk starting from zero, the probability of exiting the interval on the right is obtained. By letting N → ∞ in the fundamental matrix, the Green function on the interval [0,∞) is found, and a simple and explicit formula for the probability distribution of the point of entry into the interval (−∞,0) for the random walk starting from k = 0 results. The distributions for some related random variables are also discovered.

Applications to stress concentration calculations in discrete lattices are briefly reviewed.
On the convergence to stationarity of the many-server Poisson queue
Authors: Stadje Wolfgang , Parthasarathy P. R.
Published: April 2003

We consider the many-server Poisson queue M/M/c with arrival intensity λ, mean service time 1 and λ/c < 1. Let X(t) be the number of customers in the system at time t and assume that the system is initially empty. Then pn(t) = P(X(t) = n) converges to the stationary probability πn = P(X = n). The integrals ∫0∞[E(X)-E(X(t))]dt and ∫0∞[P(X≤n) − P(X(t)≤n)]dt are a measure of the speed of convergence towards stationarity. We express these integrals in terms of λ and c.
On an entropy conservation principle
Authors: Manuceau Jérôme , Troupé Marylène , Vaillant Jean
Published: April 2003

We present an entropy conservation principle applicable to either discrete or continuous variables which provides a useful tool for aggregating observations. The associated method of modality grouping transforms a variable Z1 into a new variable Z2 such that the mutual information I(Z2,Y) between Y, a variable of interest, and Z2 is equal to I(Z1,Y).
The distribution of time to extinction in subcritical branching processes: applications to outbreaks of infectious disease
Authors: Farrington C. P. , Grant A. D.
Published: April 2003

We consider the distribution of the number of generations to extinction in subcritical branching processes, with particular emphasis on applications to the spread of infectious diseases. We derive the generation distributions for processes with Bernoulli, geometric and Poisson offspring, and discuss some of their distributional and inferential properties. We present applications to the spread of infection in highly vaccinated populations, outbreaks of enteric fever, and person-to-person transmission of human monkeypox.
Large buffer asymptotics for the queue with fractional Brownian input
Authors: Massoulie Laurent , Simonian Alain
Published: April 2003

In this paper, a strong asymptotic estimate for the queue content distribution of a fluid queue fed by a fractional Brownian input with Hurst parameterH∊ [1/2,1[is studied. By applying general results on suprema of centred Gaussian processes, in particular, we show thatfor largex. Explicit formulae for constants κ, γ andLare given in terms ofHand system parameters.
Poisson process via martingale and related characteristics
Authors: Wesołowski Jacek
Published: April 2003

The classical martingale characterizations of the Poisson process were obtained for point process or purely discontinuous martingale i.e. under additional assumptions on properties of trajectories. Here our aim is to search for related characterizations without relying on properties of trajectories. Except for a new martingale characterization, results based on conditional moments jointly involving the past and the nearest future are presented.
Reliability of a system with Poisson inspection times
Authors: Dieulle Laurence
Published: April 2003

For systems subject to inspections at Poisson random times, we present an analytic method which gives upper and lower bounds for the reliability. We also study its asymptotic behaviour and derive the asymptotic failure rate.
Intermediate and long-term memories of associative learning are differentially affected by transcriptionversustranslation blockers inLymnaea
Authors: Sangha Susan , Scheibenstock Andi , McComb Chloe , Lukowiak Ken
Published: April 2003

Aerial respiratory behaviour in the pond snail, Lymnaea stagnalis,can be operantly conditioned. This associative learning then undergoes consolidation into a long-lasting memory which, depending on the training procedure used, causes intermediate-term memory (ITM; lasting 3 h) or long-term memory (LTM; lasting >6 h) to be formed. We determined the differential susceptibility of these two forms of memory to translation and transcription blockers. The injection of a translation blocker, Anisomycin,2.5 h before training prevents the establishment of both ITM and LTM. On the other hand, injection of the transcription blocker Actinomycin D, 2.5 h before training, did not prevent the establishment of ITM, but did, however, prevent LTM formation. Thus in Lymnaea, following associative learning, both ITM and LTM are dependent on new protein synthesis. ITM appears to be dependent on protein synthesis from preexisting transcription factors, whilst LTM is dependent on protein synthesis from new transcription messages.
A new intracellular pathway of haem detoxification in the midgut of the cattle tick Boophilus microplus: aggregation inside a specialized organelle, the hemosome
Authors: Lara Flavio Alves , Lins Ulysses , Paiva-Silva Gabriela , Almeida Igor C. , Braga Cláudia M. , Miguens Flávio C. , Oliveira Pedro L. , Dansa-Petretski Marílvia
Published: April 2003

The hard tick Boophilus microplus ingests large volumes of cattle blood, as much as 100 times its own mass before feeding. Huge amounts of haem are produced during haemoglobin digestion, which takes place inside acidic lysosomal-type vacuoles of the digest cells of the midgut. Haem is a promoter of free radical formation, so haemoglobin digestion poses an intense oxidative challenge to this animal.

In the present study we followed the fate of the haem derived from haemoglobin hydrolysis in the digest cells of the midgut of fully engorged tick females. The tick does not synthesize haem, so during the initial phase of blood digestion, absorption is the major route taken by the haem, which is transferred from the digest cells to the tick haemocoel. After this absorptive period of a few days, most of the haem produced upon haemoglobin degradation is accumulated in the interior of a specialized, membrane-delimited, organelle of the digest cell, herein called hemosome. Haem accounts for 90% of the hemosome mass and is concentrated in the core of this structure, appearing as a compact, non-crystalline aggregate of iron protoporphyrin IX without covalent modifications. The unusual FTIR spectrum of this aggregate suggests that lateral propionate chains are involved in the association of haem molecules with other components of the hemosome, which it is proposed is a major haem detoxification mechanism in this blood-sucking arthropod.
Entrepreneurship, Innovation, and Sustainability Strategies at Walden Paddlers, Inc.
Authors: Farrow Paul H. , Johnson Richard R. , Larson Andrea L.
Published: April 2003

Walden Paddlers, a market leader in popularly priced recreational kayaks, used a simple, inexpensive guide to evaluate decisions against a parameter of environmental responsibility. This guide was applied across Walden's virtual corporation structure to yield quick innovations and economic, strategic, and environmental advantages. The guide enabled Walden and its network of partners to produce light, strong, inexpensive kayaks with superior performance characteristics made from 100-percent-recycled plastic, the only such kayaks on the market. Walden also employed the guide to create a nearly waste-free product-packaging-and-shipping system. Walden's decision guide succeeded within a network of collaborative alliances because it was applied comprehensively, it helped to clarify common goals, it created benefits for all participants, and it was implemented by a skilled entrepreneur-leader who coordinated decision making in the network.
The Business of Sustainable Forestry: Meshing Operations with Strategic Purpose
Authors: Hart Stuart , Arnold Matthew , Day Rob
Published: April 2003

We developed a new framework for defining sustainable forest management (SFM) based on the literature on environmental strategy and a field study of forest-product companies. We applied the framework to 21 forest-industry business cases and found that a comprehensive and effective SFM approach meshes operations with strategic purpose. When SFM practices were embedded in core strategy, rather than appended as a matter of ethics or social responsibility, companies realized competitive and business advantages as well as environmental and social gains. Some firms have even begun to reinvent themselves as fiber-service companies as opposed to purely extractive forestry operations.
Chain or Shackles: Understanding What Drives Supply-Chain Performance
Authors: Ramdas Kamalini , Spekman Robert E.
Published: April 2003

We relate an array of factors that embody current practice and thinking in supply-chain management with supply-chain performance. We measured supply-chain performance using a set of variables that capture the impact of supply-chain management on systemwide revenues and costs. We classified supply chains based on the products they support as inherently functional or inherently innovative. They differ in practices used and thinking. High performers among innovative-product supply chains use practices that enhance revenues more than high performers among functional product supply chains. They are more likely to engage in supply-chain management to enhance revenues. Finally, we found that the practices and reasons for engaging in supply-chain management that distinguish high performers from low performers are different for functional-and innovative-product supply chains.
Growth and sexual dimorphism in orangutan crania: A three‐dimensional approach
Authors: Hens Samantha M.
Published: April 2003

New insights may be gleaned by taking an ontogenetic approach to investigations of adult dimorphism. Previous work in this area relied on traditional, caliper‐based, morphometric methods, and produced conflicting results. This study uses a three‐dimensional (3‐D) approach for both local and global form comparisons of sex‐specific growth and growth patterns. 3‐D coordinate data were collected for 20 landmarks on 94 orangutan crania divided into five developmental stages. Data were analyzed using Euclidean distance matrix analysis (EDMA). Results indicate that differences in growth patterns between male and female orangutans exist in the youngest age intervals. Dimorphic patterns are strongest in the face and basicranium at the youngest age intervals, and in the face and neurocranium during adult stages. Females grow substantially more in the cranial base and face during the youngest age groups, while males grow more than females in all anatomical regions later in development. Growth in the palate was similar between sexes. Sexual dimorphism may be produced through the continued growth of one sex relative to the other, representing differences in timing, or growth duration. Dimophism may also result from different growth rates between sexes, where one sex develops faster than the other sex in the same time interval. Orangutan males and females differ in both the rate and duration of their craniofacial development. The data analysis technique used here, EDMA, was integral in identifying dynamic growth processes rather than just the static end results of each developmental stage. Am J Phys Anthropol 121:000–000, 2003. © 2003 Wiley‐Liss, Inc.
Determination of the enantiomeric composition of chiral delta‐2‐oxazolines‐1,3 by 1H and 19F NMR spectroscopy using chiral solvating agents
Authors: Beaufour M. , Merelli B. , Menguy L. , Cherton J.‐C.
Published: April 2003

Studies of the perturbing effect of chiral solvating agents (CSAs) 5a and mostly of 5c upon the NMR spectra of chiral Δ2‐oxazoline 1 demonstrated the ability of these fluoroalcohols to afford diastereomeric solvates from these solutes. Thus, for all tested Δ2‐oxazolines 1Aa–d, 1Ba, and 1e there is at least one possibility to proceed to their enantiomeric discrimination either by 1H or 19F NMR using these CSAs (see Fig. 1). NMR results are discussed from substrate and CSA structure standpoints and a solvation model is proposed on the basis of the inequivalence senses generally observed. Then the method was applied to extracts of incubated locust tissues obtained by solid phase extraction (SPE) after a partial unmasking of the substrate 1. Chirality 15:382–390, 2003. © 2003 Wiley‐Liss, Inc.
Identification of rat cytochrome P450 forms involved in the metabolism of clausenamide enantiomers
Authors: Zhu Chuan Jiang , Zhang Jun Tian
Published: April 2003

To identify which cytochrome P450 (CYP) isoform(s) are responsible for the metabolism of clausenamide (CLA) enantiomers in rats, effects of various CYP isoform inducers and inhibitors on the formation of CLA metabolites were investigated in liver microsomes. In incubations with rat liver microsomes, CLA enantiomers were mainly converted to 4‐hydroxy, 5‐hydroxy, and 7‐hydroxy‐metabolites. 4‐OH‐CLA was the major metabolite of (+)‐3R, 4S, 5S, 6R‐CLA [(+)‐CLA], while 7‐OH‐CLA was the major one of (−)‐3S, 4R, 5R, 6S‐CLA [(−)‐CLA]. In induction studies, enzymatic parameters were used to assess the role of different CYP forms in CLA hydroxylation reactions. A marked increase in the rate of metabolism of CLA enantiomers was observed in microsomes of dexamethasone treated rats, Vmax/Km values for 4‐OH‐(+)‐CLA, 7‐OH‐, 5‐OH‐, and 4‐OH‐(−)‐CLA were 5.3, 6.5, 3.0, and 5.9 times higher than those in control microsomes, respectively. Rifampicin treatment caused corresponding 1.7‐, 2.6‐, 3.1‐, and 2.8‐fold increases. Dex and Rif also increased in the amount of (+)‐5‐ and (+)‐7‐OH‐CLA that were not detectable in the control group. These results suggested that inducible CYP3A1 was involved in the hydroxylation of CLA enantiomers. In inhibition studies, ketoconazone (6.25 μM) completely inhibited the production of main metabolites of (−)‐CLA (100%) and (+)‐CLA (97%). Triacetyloleandomycin (12.5 μM) strongly inhibited the corresponding metabolites by 34–85%. These findings also indicated that institutive CYP3A2 shared a major role in the hydroxylation of CLA enantiomers with CYP3A1 in untreated rats. Together, the data suggested that CYP3A was the predominant isoform responsible for the metabolism of CLA enantiomers. Chirality 15:448–455, 2003. © 2003 Wiley‐Liss, Inc.
Cadherin expression coincides with birth dating patterns in patchy compartments of the developing chicken telencephalon
Authors: Heyers Dominik , Kovjanic Dragica , Redies Christoph
Published: April 2003

Some gray matter regions of the vertebrate brain, e.g., the mammalian striatum, are organized into clusters of functionally similar neurons (“patches”) that are surrounded by a gray matter matrix. A similar type of compartmentation recently has been found also in the avian telencephalon, based on two sorts of evidence. First, a birth dating study showed that, in some telencephalic areas, cells born at the same time form “isochronic” cell clusters, which differ in their birth dating pattern from their surrounding tissue. Second, patchy expression was found for different members of the cadherin family of adhesion molecules (R‐cadherin, N‐cadherin, and/or cadherin‐7). The relation between these two findings has remained unclear. Here, we demonstrate a general spatial coincidence between the birth dating patterns and the heterogeneities in cadherin expression. This coincidence is found in areas of the avian ventral and lateral pallium (ventral hyperstriatum, neostriatum, and ectostriatum) and in a part of the archistriatum, which is of pallial origin. For example, in the neostriatum, a part of the ventral pallium, both the cadherin‐7–positive patches and their R‐cadherin–positive surroundings are born between embryonic day 5 and 7, but the cadherin‐7–positive cells are born during a shorter time period than the R‐cadherin–positive cells. We propose that the patchy gray matter architecture observed in the mammalian striatum and avian pallium are regulated by a common type of morphogenetic mechanism. This mechanism possibly involves the differential expression of adhesive factors, such as cadherins. J. Comp. Neurol. 460:155–166, 2003. © 2003 Wiley‐Liss, Inc.
Quantitative study of the coexpression of Fos and N‐methyl‐D aspartate (NMDA) receptor subunits in otolith‐related vestibular nuclear neurons of rats
Authors: Chen Liang‐Wei , Lai Chun‐Hong , Law Hoi‐Yan , Yung Ken K.L. , Chan Ying‐Shing
Published: April 2003

The expression of NMDA receptor subunits (NR1 and NR2A/B) was demonstrated immunocytochemically in otolith‐related neurons within the vestibular nuclear complex and its subnuclei of conscious Sprague‐Dawley adult rats. All experimental animals were subjected to constant velocity off‐vertical axis rotation (OVAR). The rotating gravity vector during OVAR sequentially activates hair cells on all sectors of the utricular maculae; neurons so activated within the vestibular nuclei were denoted by the expression of Fos protein. Control animals, i.e., labyrinthectomized rats subjected to OVAR and normal rats that remained stationary, showed only a few sporadically scattered labeled neurons. In the brainstem of normal rats subjected to OVAR, a high density of Fos‐immunoreactive (Fos‐ir) neurons was found in the vestibular nuclear complex (namely, spinal vestibular nucleus, SpVe; medial vestibular nucleus, Mve; superior vestibular nucleus, SuVe) and subnuclei (namely, group x and group y), whereas a lower density was found in the lateral vestibular nucleus (LVe). A double‐immunofluorescence study indicated that both NR1 and NR2A/B subunits were highly expressed in Fos‐ir neurons within the vestibular nuclei. Fos/NR1 or Fos/NR2A/B double‐labeled neurons constitute over three‐quarters of the total number of Fos‐ir neurons in SpVe, MVe, LVe, SuVe, and groups x and y. Our findings suggest that NMDA‐type ionotropic glutamate receptors play a key role in the OVAR‐induced neuronal activation of the vestibular nuclei, thus providing a morphological basis for further study of glutamatergic central otolith neurons and their involvement in sensorimotor regulation and autonomic functions of rats. J. Comp. Neurol. 460:292–301, 2003. © 2003 Wiley‐Liss, Inc.
Remote adaptation effect on perceived subjective color: A model approach
Authors: Tsofe Avital , Rotgold Gil , Spitzer Hedva
Published: April 2003

An elaborated subjective color model is presented that includes the predictions of emulated Benham disk results and additional predictions that refer to local and remote achromatic illuminations on perceived subjective color shifts. A computer emulated Benham disk pattern was used as a stimulus to test the effects of remote illumination on its color sensation. An analytical model and its predictions are proposed in order to account for the results of the perceived hue shift, when changing either the remote illumination area or the stimulus illumination. This model is based on previous retinal color‐coded cells responses which yield the subjective color, and on local and remote adaptation mechanisms. The similarity between the role and mechanism of remote illumination (achromatic or chromatic) in subjective and perceived color is also discussed. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 197–208, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10145
Metaphor as a method in the domain of marketing
Authors: Cornelissen Joep P.
Published: April 2003

Prior research has laid the groundwork for a discussion of the role of metaphor in marketing, but has fallen short of offering a clear‐cut method for guiding and evaluating its use. This article outlines such a method, and illustrates its use through extended discussions of the heuristic status of corporate identity and relationship marketing as metaphors for the generation of knowledge about the subjects that both supposedly illuminate. Implications of this methodology of metaphor for marketing research are outlined. © 2003 Wiley Periodicals, Inc.
Using cavity model analysis to design a dual‐band dual‐slant‐polarized microstrip antenna
Authors: Chakravarty Tapas , De Asok
Published: April 2003

A novel method of computation of input impedance detected by a feed probe leads to a simple technique of designing a dual‐band dual‐polarized microstrip antenna using a shorting‐pin‐loaded circular patch. The computation of the radiation pattern displays a slant‐polarized antenna, in which the tilt angle follows the angular location of the shorting pin. Comparisons with simulated results show good agreement. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 331–337, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10910
Slant 45° beam steering using a capacitive loaded patch antenna
Authors: Li R. L. , Fusco V. F.
Published: April 2003

In this paper we suggest a method for loading a microstrip patch antenna with two capacitive reactances in such a way that beam steering over a restricted range can be obtained. We show that by varying these capacitances we can maintain a reasonable VSWR < 3 while steering the beam over about 45° in a cut positioned at ϕ = 135° (slant −45° linear polarisation). Such an antenna offers the prospect for refinement as an element in a thinned array for use in a base station array. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 352–355, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10915
Broadband dual‐polarization stacked microstrip antennas for Bluetooth applications
Authors: Chen Zhi Ning , See T. S. P. , Chia M. Y. W.
Published: April 2003

In this paper, a novel linear dual‐polarized stacked microstrip antenna that operates well within the ISM band (2.40–2.4835 GHz) for Bluetooth applications is experimentally presented. The square patch of the microstrip antenna is fed diagonally by a microstrip line. Another square patch with a superstrate is stacked above the corner‐fed patch in order to increase the operating bandwidth. The impedance and radiation characteristics of the optimized antenna configuration are presented, with variations of the sizes of the top and bottom patches and the spacing between the patches. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 364–366, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10919