bluuebunny/crossref_metadata_2025 huggingface dataset:
Functional [6]Pericyclynes: Aromatization to Substituted carbo‐Benzenes
Authors: Saccavini Catherine , Sui‐Seng Christine , Maurette Luc , Lepetit Christine , Soula Sabine , Zou Chunhai , Donnadieu Bruno , Chauvin Remi
Published: March 2007

Reductive treatment of stereoisomeric mixtures of variously substituted hexaoxy[6]pericyclynes with SnCl2/HCl led to the corresponding substituted carbo‐benzenes. Tetramethoxyhexaphenyl[6]pericylynediol and dimethoxyhexaphenyl[6]pericyclynetetrol thus proved to be alternative precursors of hexaphenyl‐carbo‐benzene, previously described. Another hexaaryl‐carbo‐benzenic chromophore with 4‐pyridyl and 4‐anisyl substituents was targeted for its second‐order nonlinear optical properties and was obtained by aromatization of a dimethoxy[6]pericyclynetetrol. Two alkynyl substituents in para positions were also found to be compatible with the C18 carbo‐benzene ring, provided that the four remaining vertices are substituted by phenyl groups. In the protected series, bis(trimethylsilylethynyl)hexaphenyl‐carbo‐benzene (C18Ph4(CCTMS)2) could be isolated and fully characterized, even by X‐ray crystallography. In the bis‐terminal series, the diethynylhexaphenyl‐carbo‐benzene C18Ph4(CCH)2 could not be isolated in the pure form. It could, however, be generated by two different methods and identified by the corresponding 1H NMR spectra. Unsubstituted carbo‐benzene C18H6 remains unknown, but tetraphenyl‐carbo‐benzenes C18Ph4H2 with two unsubstituted vertices proved to be viable molecules. Whereas the “para” isomer could be characterized by MS and 1H and 13C NMR spectroscopy only in a mixture with polymeric materials, the “ortho” isomer (with adjacent CH vertices) could be isolated, and its structure was determined by using X‐ray crystallography. The structure calculated at the B3PW91/6‐31G** level of theory turned out to be in excellent agreement with the experimental structure. The 1H and 13C NMR chemical shifts of hexa‐ and tetraphenyl‐carbo‐benzenes were also calculated at the B3LYP/6‐31+G** level of theory and were found to correlate with experimental spectra. The remote NMR deshielding of peripheral protons (through up to five bonds) revealed a very strong diatropic circulation around the C18 ring, regardless of the substitution pattern. In full agreement with theoretical investigations, it has been demonstrated experimentally that the carbo‐benzene ring is “independently” aromatic, in accord with structural–energetic and –magnetic criteria.
Silver versus Gold Catalysis in Tandem Reactions of Carbonyl Functions onto Alkynes: A Versatile Access to Furoquinoline and Pyranoquinoline Cores
Authors: Godet Thomas , Vaxelaire Carine , Michel Carine , Milet Anne , Belmont Philippe
Published: March 2007

An efficient and versatile tandem process of acetalization and cycloisomerization reactions has been developed for the reactions of 1‐alkynyl‐2‐carbonylquinoline substrates. The reaction occurs thanks to AuI and AgI catalysis. Silver(I) catalysis has been extensively studied (11 different silver species) on a broad range of quinoline derivatives (variation of alkyne substituent, of carbonyl function and of nucleophiles), leading to a variety of furoquinoline and pyranoquinoline moieties. An insight is given for the presumed mechanism along with DFT‐B3 LYP/6–31G** calculations to address the 6‐endo and 5‐exo regioselectivities observed.
Highly Potent Fluorescence‐Tagged Nonimidazole Histamine H3 Receptor Ligands
Authors: Amon Michael , Ligneau Xavier , Camelin Jean‐Claude , Berrebi‐Bertrand Isabelle , Schwartz Jean‐Charles , Stark Holger
Published: March 2007

Different (3‐phenoxypropyl)piperidine derivatives have been coupled to fluorescent moieties (5‐dimethylaminonaphthalene‐1‐sulfonyl, carbazol‐9‐ylcarbonyl, 2‐cyanoisoindol‐1‐yl, 2‐cyanobenzo[f]isoindol‐1‐yl, 2,4‐dinitrobenzen‐1‐yl, 2,4‐diaminophenyl, 7‐nitrobenzofurazan‐4‐yl, 7‐aminosulfonylbenzofurazan‐4‐yl, 4‐methylcoumarin‐6‐yl) as novel histamine H3 receptor ligands. They have been synthesised starting from piperidine in a few steps. The compounds display good to excellent histamine hH3 receptor affinities with Ki values ranging from 13.4 to 0.048 nM. Some of the new compounds belong to the most potent ligands known so far and may act as tools for identification and understanding of the binding site on the histamine H3 receptor. In vivo screening on selected derivatives of Sanger’s reagent showed antagonist potencies with ED50 values from 7.9 to 0.39 mg kg−1, p.o.
Velocity averaging, kinetic formulations, and regularizing effects in quasi‐linear PDEs
Authors: Tadmor Eitan , Tao Terence
Published: March 2007

We prove in this paper new velocity‐averaging results for second‐order multidimensional equations of the general form ℒ︁(∇x,v)f(x, v) =g(x, v) where ℒ︁(∇x,v) :=a(v) · ∇x− ∇·b(v)∇x. These results quantify the Sobolev regularity of the averages, ∫vf(x, v)ϕ(v)dv, in terms of the nondegeneracy of the set {v: |ℒ︁(iξ,v)| ≤ δ} and the mere integrability of the data, (f, g) ∈ (L,L). Velocity averaging is then used to study theregularizing effectin quasi‐linear second‐order equations, ℒ︁(∇x, ρ)ρ =S(ρ), which use their underlying kinetic formulations, ℒ︁(∇x, v)χρ=gS. In particular, we improve previous regularity statements for nonlinear conservation laws, and we derive completely new regularity results for convection‐diffusion and elliptic equations driven by degenerate, nonisotropic diffusion. © 2007 Wiley Periodicals, Inc.
Computing the 1H NMR Spectrum of a Bulk Ionic Liquid from Snapshots of Car–Parrinello Molecular Dynamics Simulations
Authors: Bagno Alessandro , D'Amico Fabio , Saielli Giacomo
Published: March 2007

We have investigated the performance of several computational protocols in predicting the NMR spectrum of a molecular ion in a complex liquid phase such as an ionic liquid. To do this, we computed the proton NMR chemical shifts of the 1‐ethyl‐3‐methylimidazolium cation [emim]+ in [emim][Cl]. Environmental effects on the imidazolium ring proton chemical shifts are quite significant and must be taken into account explicitly. Calculations performed on the isolated imidazolium cation as well as on the [emim][Cl] ion pair grossly fail to reproduce the correct spacing between proton signals. In contrast, calculations performed on clusters extracted from the trajectory of a Car–Parrinello molecular dynamics simulation yield very good results.
Ethanol Adsorption, Decomposition and Oxidation on Ir(111): A High Resolution XPS Study
Authors: Weststrate Cornelis J. , Ludwig Wiebke , Bakker Johan W. , Gluhoi Andreea C. , Nieuwenhuys Bernard E.
Published: March 2007

Ethanol (C2H5OH) adsorption, decomposition and oxidation is studied on Ir(111) using high‐energy resolution, fast XPS and temperature‐programmed desorption. During heating of an adsorbed ethanol layer a part of the C2H5OHad desorbs molecularly, and another part remains on the surface and decomposes around 200 K; these two decomposition pathways are identified, as via acetyl (H3CCO) and via COad+CH3ad, respectively. Acetyl and CH3ad decompose around 300 K into CHad (and COad). CHad decomposes forming Cx and H2 around 520 K. In the presence of Oad an acetate intermediate is formed around 180 K, as well as a small amount of CH3ad and COad. Acetate decomposes between 400–480 K into CO2, H2(/H2O) and CHad.
Data quality assessment of ungated flow cytometry data in high throughput experiments
Authors: Le Meur Nolwenn , Rossini Anthony , Gasparetto Maura , Smith Clay , Brinkman Ryan R. , Gentleman Robert
Published: March 2007

Background:

The recent development of semiautomated techniques for staining and analyzing flow cytometry samples has presented new challenges. Quality control and quality assessment are critical when developing new high throughput technologies and their associated information services. Our experience suggests that significant bottlenecks remain in the development of high throughput flow cytometry methods for data analysis and display. Especially, data quality control and quality assessment are crucial steps in processing and analyzing high throughput flow cytometry data.

Methods:

We propose a variety of graphical exploratory data analytic tools for exploring ungated flow cytometry data. We have implemented a number of specialized functions and methods in the Bioconductor package rflowcyt. We demonstrate the use of these approaches by investigating two independent sets of high throughput flow cytometry data.

Results:

We found that graphical representations can reveal substantial nonbiological differences in samples. Empirical Cumulative Distribution Function and summary scatterplots were especially useful in the rapid identification of problems not identified by manual review.

Conclusions:

Graphical exploratory data analytic tools are quick and useful means of assessing data quality. We propose that the described visualizations should be used as quality assessment tools and where possible, be used for quality control. © 2007 International Society for Analytical Cytology
Analysis of nitrosamines by capillary electrospray‐high‐field asymmetric waveform ion mobility spectrometry‐MS with programmed compensation voltage
Authors: Liu Xin , Zhao Yuan‐Yuan , Chan Kenneth , Hrudey Steve E. , Li Xing‐Fang , Li Jianjun
Published: March 2007

Emerging disinfection by‐products (DBPs) in drinking water are an important public health concern. Certain DBPs, such as nitrosamines, are probable carcinogens, and exposure to halogenated DBPs may lead to birth defects. It is difficult to obtain complete separation of nitrosamines by chromatographic techniques. Thus we explored high‐field asymmetric waveform ion mobility spectrometry (FAIMS) as an alternative separation technique for the characterization of individual DBPs in a complex matrix. We first used ESI‐FAIMS‐MS to separate four nitrosamines: N‐nitrosodi‐n‐butylamine (NDBA), N‐nitrosodi‐n‐propylamine (NDPA), N‐nitrosopiperidine (NPip), and N‐nitrosodiethylamine (NDEA) in the compensation voltage (CV) spectra. The optimal CVs with a fixed dispersion voltage of –4000 V were found to be –1.2 V (NDBA), 2.7 V (NDPA), 7.5 V (NPip) and 10.1 V (NDEA). In addition, FAIMS‐MS effectively reduced the chemical noise and dramatically improved the LODs by as much as tenfold compared to the conventional ESI‐MS technique. To further improve sensitivity, an on‐line CE system was used in combination with FAIMS‐MS to take advantage of the higher ionization efficiency. The calibration curves for the four nitrosamines were linear over a range of 5 ng/mL to 1000 ng/mL with an r2 value of 0.9929 to 0.9992. To increase sample throughput, a multiple‐injection strategy was developed, in which the CV values were preprogrammed so that the FAIMS device allowed different nitrosamines to pass through at selected time windows. The potential application of the proposed method was demonstrated for the analysis of drinking water samples spiked with nitrosamines.
Environmental pollution analysis by dynamic structural equation models
Authors: Fontanella Lara , Ippoliti Luigi , Valentini Pasquale
Published: March 2007

As requested by the framework EU Directive on air quality assessment and management (96/62/EC) and related ‘daughter’ directives, air quality standards for specific pollutants are designed to protect public health and environment. Modeling is one of the main activities to evaluate air quality and to prepare future control programs. Of course, this is not an easy task since a variety of pollutants may undergo chemical reactions between themselves and with other species. Nevertheless, in this paper we attempt to discuss a framework to construct a multivariate model which is able to capture the dynamical interactions among pollutants and meteorological variables. Specifically, assuming that latent or background effects underlying the fluctuation of observations can be estimated, a dynamic structural equation model is developed in a state‐space form. A research study on the Milan district for data provided by the Lombardia Environmental Protection Agency (ARPA) is presented. Copyright © 2007 John Wiley & Sons, Ltd.
Clustering composition vectors using uncertainty information
Authors: Christensen William F. , Dillner Ann M. , Schauer James J. , Reese C. Shane
Published: March 2007

In the biological and environmental sciences, interest often lies in using multivariate observations to discover natural clusters of objects. In this manuscript, the incorporation of measurement uncertainty information into a cluster analysis is discussed. This study is motivated by a problem involving the clustering of composition vectors associated with each of several chemical species. The observed abundance of each component is available along with its estimated uncertainty (measurement error standard deviation). An approach is proposed for converting the abundance vectors into composition (relative abundance) vectors, obtaining the covariance matrix associated with each composition vector, and defining a Mahalanobis distance between composition vectors that are suitable for cluster analysis. The approach is illustrated using particle size distributions obtained near Houston, Texas in 2000. Computer simulation is used to compare the performance of Mahalanobis‐distance‐based and Euclidean‐distance‐based clustering approaches. The use of a modified Mahalanobis distance along with Ward's method is recommended for use. Copyright © 2007 John Wiley & Sons, Ltd.
Nonlinear dynamic analysis of complex structures
Authors: Wilson E. L. , Farhoomand I. , Bathe K. J.
Published: March 2007

A general step‐by‐step solution technique is presented for the evaluation of the dynamic response of structural systems with physical and geometrical nonlinearities. The algorithm is stable for all time increments and in the analysis of linear systems introduces a predictable amount of error for a specified time step. Guidelines are given for the selection of the time step size for different types of dynamic loadings. The method can be applied to the static and dynamic analysis of both discrete structural systems and continuous solids idealized as an assemblage of finite elements. Results of several nonlinear analyses are presented and compared with results obtained by other methods and from experiments.
A stochastic model for predicting seismic failure in a soil deposit
Authors: Faccioli Ezio
Published: March 2007

Liquefaction of saturated sand deposits under seismic excitation is studied on the basis of a fatigue failure approach. The model includes a stochastic treatment of the input, of the soil response and of the cumulative pore pressure effects produced by cycling stresses in the soil. A method of establishing safety factors against liquefaction is also considered. Results obtained from analysis of a case history confirm the applicability of the model for engineering purposes.
Stochastic excitation of a simple system with impact damper
Authors: Masri S. F. , Ibrahim A. M.
Published: March 2007

An approximate analytical solution is obtained for the stationary response of a highly nonlinear auxiliary mass damper (impact damper) attached to a single‐degree‐of‐freedom oscillator that is subjected to an excitation with white power spectral density and Gaussian probability distribution. Experimental measurements with an electronic analogue computer verify the analytical findings both qualitatively and quantitatively. Results are given for the mean‐squared level and the power spectral density of the response. The effects of various damper parameters on the response of the primary system are determined. The impact damper under consideration is shown to be substantially more effective than the conventional dynamic vibration neutralizer in controlling the response of stochastically excited primary systems.
Effects of stiffness degradation on ductility requirements for multistorey buildings
Authors: Chopra Anil K. , Kan Christopher
Published: March 2007

The effect of stiffness degradation in reinforced concrete structural members on the inelastic response of multistorey buildings to earthquakes is investigated. In particular, the following question is examined. How do the ductility requirements for multistorey systems with degrading stiffness behaviour compare with those for structures with ordinary bilinear hysteretic property? Inelastic dynamic responses of two idealized multistorey buildings, one having a long and the other a relatively short fundamental period, to an ensemble of twenty simulated earthquakes representative of moderately intense ground motions in California at moderate epicentral distances on firm ground, are analysed for ordinary bilinear hysteretic behaviour and for bilinear hysteretic behaviour with stiffness degradation property. The conclusions deduced from the results of this investigation include the following

(1) It is, in general, not possible to predict the maximum response of a degrading stiffness system from results for the corresponding ordinary bilinear system

(2) The differences in ductility requirements due to stiffness degradation are generally smaller than those associated with probabilistic variability from one ground motion to another

(3) Stiffness degradation has little influence on the ductility requirements for flexible buildings, but it leads to increased ductility requirements for stiff buildings.
Vibration of viscoelastic foundations
Authors: Veletsos A. S. , Verbič B.
Published: March 2007

Simple approximate solutions are presented for the steady‐state response of a massless, rigid disk, which is supported at the surface of a linear viscoelastic halfspace and is excited by a harmonically varying horizontal or vertical force, or by a harmonically varying moment about an axis in the plane of the disk. The halfspace is idealized either as a standard Voigt solid or as a constant hysteretic solid. The solution for the massless disk is then applied to the analysis of foundations with mass, and for each mode of excitation, comprehensive numerical data are presented to illustrate the effects of viscoelastic action on the response of both the massless disk and of foundations with mass

It is shown that the principal effects of material damping are to increase the damping capacity of the foundation and to reduce its ‘natural’ frequency. In the mathematically equivalent representation of the elastically supported massless disk as a spring‐dashpot combination without mass, it is shown that the effective stiffness of the spring may become negative over significant ranges of the exciting frequency, and that it is preferable to model the disk‐halfspace system as an oscillator with mass, taking its spring constant equal to the static stiffness of the original system.
Prediction of buckling strengths of cylindrical shells from their natural frequencies
Authors: Radhakrishnan R.
Published: March 2007

The instability of thin elastic shells still remains the most challenging of all the classical problems of the theory of elasticity. It is the aim of this investigation to verify a rational experimental technique for predicting the buckling loads of cylindrical tubes under axial load as well as under external radial pressure, by measuring their natural frequencies under different loadings. Cylindrical tubes made of Hostaphan (thickness 0·254 mm and radius 100 mm) were tested under axial load and under external radial pressure in the German Air and Space Research Laboratory (Deutsche Forschungsanstalt für Luft und Raumfahrt) at Braunschweig, West Germany, and the results compared with an actual buckling test. The tests revealed that the buckling load can be predicted satisfactorily by the proposed non‐destructive vibration method of testing.
Earthquake interaction forces between two structures of different rigidities
Authors: Ban Shizuo
Published: March 2007

A combined structure is assumed to be composed of a rigid part and a flexible part. Each component structure would have a different period of natural vibration if it were built independently. When they are combined in one structure and subjected to an earthquake, there must be generated some interaction forces so that the component structures will have a common vibration. In this paper is an analytical method described to evaluate such interaction forces

The general principle is as follows. For each of the component structures, equations of motion taking account of the unknown interaction forces are derived first. Then by eliminating the interaction forces, equations of motion of the combined structure are obtained. After solving these equations and substituting the solution into the equations of motion of the component structures, the unknown interaction forces are obtained directly

In the present paper, two structures corresponding to two‐degree elastic systems are considered; numerical examples also are included.
Earthquake analysis of gravity dams including hydrodynamic interaction
Authors: Chakrabarti P. , Chopra Anil K.
Published: March 2007

A general procedure for analysis of the response of gravity dams, including hydrodynamic interaction and compressibility of water, to the transverse horizontal and vertical components of earthquake ground motion is presented. The problem is reduced to one in two dimensions considering the transverse vibration of a monolith of a dam, and the material behaviour is assumed to be linearly elastic

The complete system is considered as composed of two substructures—the dam, represented as a finite element system, and the reservoir, as a continuum of infinite length in the upstream direction governed by the wave equation. The structural displacements of the dam (including effects of water) are expressed as a linear combination of the modes of vibration of the dam with the reservoir empty. The effectiveness of this analytical formulation lies in its being able to produce excellent results by considering only the first few modes. The complex frequency response for the modal displacements are obtained first. The responses to arbitrary ground motion are subsequently obtained with the aid of the Fast Fourier Transform algorithm

An example analysis is presented to illustrate results obtained from this method. It is concluded that the method is very effective and efficient and is capable of producing results to any desired degree of accuracy by including the necessary number of modes of vibration of the dam.
Response of rectangular orthotropic plates to random excitations
Authors: Sundararajan C. , Reddy D. V.
Published: March 2007

The paper describes the application of the finite strip method, a modification of the finite element method, to determine the random response of rectangular plates. An example problem of a rectangular orthotropic plate, simply supported on two opposite edges and clamped on the other two, under acoustic white noise excitation is solved.
Earth Dam‐foundation interaction during earthquakes
Authors: Idriss I. M. , Mathur J. M. , Bolton Seed H.
Published: March 2007

Several significant parameters that could affect interaction in a dam‐foundation system are discussed. These parameters are: (1) Fundamental periods of the dam and the foundation layer. (2) Lateral extent of the dam. (3) The material properties of the dam and the foundation layer. Five cases are analysed to illustrate the influence of these parameters on interaction. An interaction ratio, R1, relating the response of the dam‐foundation system at the base of the dam to the free field response is introduced and interaction effects are expressed in terms of this ratio; the smaller this ratio, the less are the interaction effects. For very small values of R1, it is shown that the dam‐foundation system could be decoupled

The results of the studies presented in the paper suggest that the interaction effects cannot be uniquely related to either the ratio of the period of the dam to the period of the foundation layer, or to the material properties of the dam and foundation layer. However, for the limited number of cases investigated, the interaction effects were found to be uniquely related to the ratio D/B, where D is the depth of the foundation layer and B is the width of the dam section. For values of D/B less than unity, strong interaction effects were obtained and the dam‐foundation system could only be analysed as a coupled system. For values of D/B greater than unity, the interaction appeared negligible and the dam and its foundation layer could be decoupled. It should be noted, however, that for very small values of D/B the interaction effects would decrease becaase as D approaches zero, there would be no interaction

The use of the interaction ratio, R1, and the parameter D/B should aid in assessing the need for analysing the response of the dam‐foundation as a coupled or as a decoupled system.
Stochastic considerations in seismic analysis of structures
Authors: Singh M. P. , Chu S. L.
Published: March 2007

A method is presented for stochastic modelling of a design earthquake by a power spectral density function for seismic analysis of structures. The method can be adopted with information currently available in the form of design response spectra for earthquake motion. Accurate seismic responses of structures can be easily obtained using such stochastic models. The methods for accurate response analysis of structures with closely spaced modes and for generation of floor response spectra of a building using a prescribed ground response spectrum directly are also presented. The hypothesis that a design earthquake can be modelled by a power spectral density function is used only implicitly in developing these methods.
Modal analysis of coupled motion of horizontally excited embedded footings
Authors: Beredugo Y. O.
Published: March 2007

A modal analysis formulation of the equations of motion of horizontally excited embedded footings is presented. Numerical solutions obtained with these equations are compared with the results obtained from direct solutions. It is shown that the two methods of solution are in good agreement for frequencies near to the first resonance.
Correlations of peak acceleration, velocity and displacement with earthquake magnitude, distance and site conditions
Authors: Trifunac M. D. , Brady A. G.
Published: March 2007

A brief review of proposed correlations between peak accelerations and earthquake magnitude and distance has been presented. It has been found that most investigators agree favourably on what should be the amplitude of peak accelerations for the distance range between about 20 and 200 km. For distances less than 20 km, there is significant disagreement in the predicted peak amplitudes, reflecting the lack of data there and the uncertainties associated with the extrapolation.

Correlations of peak accelerations, peak velocities and peak displacements with earthquake magnitude, epicentral distance and the geologic conditions of the recording sites have been presented for 187 accelerograms recorded during 57 earthquakes. This data set describes strong earthquake ground motion in the Western United States during the period from 1933 to 1971.

For large earthquakes, dependence of peak acceleration, velocity and displacement amplitudes on earthquake magnitude seems to be lost. This suggests that the amplitudes of strong ground motion close to a fault are scaled primarily by the maximum dislocation amplitudes and the stress drop, rather than the overall ‘size’ of an earthquake as measured by magnitude.

The influence of geologic conditions at the recording station seems to be of minor importance for scaling peak accelerations, but it becomes noticeable for the peaks of velocity and even more apparent for the peaks of displacement.
Dynamic transient behaviour of two‐ and three‐dimensional structures including plasticity, large deformation effects and fluid interaction
Authors: Shantaram D. , Owen D. R. J. , Zienkiewicz O. C.
Published: March 2007

The finite element method is employed in the prediction of the dynamic transient response of two‐ and three‐dimensional solids exhibiting geometric (large deformations) and material (elasto‐plastic) non‐linearities. Explicit time marching schemes are adopted for integration of the dynamic equilibrium equation and a diagonal ‘lumped’ mass matrix is employed with a special procedure applicable to parabolic isoparametric elements. A variety of problems are presented including a solid/fluid interaction situation, and the method is shown to be able to solve economically many problems of dynamic or catastrophic nature which can occur in such structures as nuclear reactors, containment vessels, etc.
Comparative analysis of the seismic risk in sites of different seismicity
Authors: Grandori G. , Petrini V.
Published: March 2007

Four sites (a, b, c, d) are considered of differing seismicity. The calculations, for two different buildings on each site, consisted of:

The total monetary cost as a function of the design seismic coefficient c.

The marginal cost of a saved life, ΔD/ΔL, also depending on c.

The ratios between the design seismic coefficients in the various sites, cd/ca, cd/cb, cd/cc, that lead to the same marginal cost ΔD/ΔL in all sites.

The marginal cost ΔD/ΔL turns out to be highly sensitive to uncertainties, but the other ratios are scarcely influenced by the uncertainties met in analysing the problem. This would suggest the adoption of a rationalized principle for comparing the levels of severity in the Codes for sites with differing degrees of seismicity.

If a criterion for evaluating indirect cost due to damage or collapse is fixed for each building and each site the values of c corresponding to minimum monetary cost are not strongly influenced by the said uncertainties. This would make it possible to look into the problem of the minimum levels of severity in the Codes. Of course, this assumes that the levels of severity should always be higher than those corresponding to the minimum monetary cost.
Contact stresses and ground motion generated by soil‐structure interaction
Authors: Wong H. L. , Luco J. E. , Trifunac M. D.
Published: March 2007

A study has been made of the dynamic contact stresses that the foundation of a nine‐storey reinforced concrete building exerts on the soil during forced vibration tests. The effects of the flexibility of the foundation on the contact stress distribution and on the force‐displacement relationship for the foundation have been examined in an attempt at testing several simplifying assumptions commonly used in soil‐structure interaction studies. Comparisons of calculated and observed ground displacements induced by soil‐structure interaction in the immediate neighbourhood of the building have also been presented.
Free vibrations of open‐section shear walls
Authors: Mukherjee Priya R. , Coull Alexander
Published: March 2007

The coupled torsional‐flexural vibration of open‐section shear walls, braced by connecting beams at each floor level, is analysed on the basis of Vlasov's theory of thin‐walled beams. The basic dynamic equations and boundary conditions are derived from Hamilton's principle, and a numerical solution obtained by the Ritz‐Galerkin method. In addition to the primary torsional and flexural inertias, secondary effects due to rotatory and warping inertia forces have also been taken into account. The method is suitable for both rigid and flexible base conditions.

A series of numerical examples is presented in which analytical results are compared with available experimental data, and the effects of secondary inertia forces, base flexibility and connecting beams upon the vibration characteristics of such shear walls are examined for two different structural forms.
Frequency analysis of coupled shear wall assemblies
Authors: Cheung Y. K. , Hutton S. G. , Kasemset C.
Published: March 2007

The finite strip procedure is used to predict the free vibration response of both planar and non‐planar coupled shear wall assemblies. The solid walls are considered as vertical cantilever strips and a comparison is made between modelling the spandrel beams as discrete beams and as an equivalent continuum with orthotropic plate properties. It is shown that both approaches lead to essentially the same frequencies. The effects of vertical inertial forces and shear deflection are included, and structures considered may have properties that vary with height. The method presented appears to be more versatile than previously published techniques and numerical comparisons with existing methods indicate the predicted results to be accurate.
Seismic risk analysis of discrete system of sites
Authors: Taleb‐Agha Ghiath , Whitman Robert V.
Published: March 2007

Two efficient schemes have been developed for the analysis of discrete systems of sites. Both schemes have the same objective of finding the probability of simultaneous failure of any number of sites belonging to a given system of sites subject to threats from a given set of earthquake sources with known seismic history. In the first scheme, systems with deterministic site resistances can effectively be analysed using a non‐linear transformation of variables. In the second scheme, systems with random site resistances can be analysed. To overcome the computational difficulties involved in the analysis, a new set of simple recursive formulas has been developed and used effectively. Based on these two schemes, two efficient computer programs were prepared and used to perform a parametric study on a system of nine actual or contemplated nuclear power plants in New England. The results have shown that the problem is very sensitive to the coefficient of variation of the resistances and not so sensitive to the mean resistances.
Selenium‐Containing Heterocycles from Isoselenocyanates: Synthesis of 1,3‐Selenazinane and 1,3‐Selenazinanone Derivatives
Authors: Sommen Geoffroy L. , Linden Anthony , Heimgartner Heinz
Published: March 2007

The reaction of the intermediate ketene N,Se‐hemiacetal 3, prepared from cyanomethylene derivatives 1 by treatment with Et3N and aryl isoselenocyanates 2, with bis‐electrophiles 6, 7, 9, and 11 in DMF affords tetrahydro‐1H‐1,3‐selenazine (=1,3‐selenazinane) derivatives 8, 10, and 12 in good yield (Scheme 2 and Tables 1–3). Chemical and spectroscopic evidence for the structures of the new compounds are described. The structures of 8d and 12e are established by X‐ray crystallography (Figs. 1 and 2).
New Syntheses of Retinal and Its Acyclic Analog γ‐Retinal by an Extended Aldol Reaction with a C6 Building Block That Incorporates a C5 Unit after Decarboxylation. A Formal Route to Lycopene and β‐Carotene
Authors: Valla Alain , Valla Benoist , Le Guillou Régis , Cartier Dominique , Dufossé Laurent , Labia Roger
Published: March 2007

Since the C15 β‐end‐group aldehyde 10 ((β‐ionylidene)acetaldehyde), an excellent intermediate in the syntheses of retinoids, can be synthesized in many ways from β‐ionone, and since the corresponding acyclic C15 ψ‐end‐group aldehyde 5 can easily be synthesized from citral (1) (Scheme 3), we applied the C15+C5 route to the syntheses of γ‐retinal ((all‐E)‐8) (Scheme 3) and retinal ((all‐E)‐13) (Scheme 4), and therefore, by coupling (2×C20→C40), to the preparation of lycopene (14) and β‐carotene (15) (Scheme 5). Our new syntheses of retinal ((all‐E)‐13) and γ‐retinal ((all‐E)‐8 use an extended aldol reaction with a C6 building block that incorporates a C5 unit after decarboxylation.
Nucleosides and Oligonucleotides with Diynyl Side Chains: Base Pairing and Functionalization of 2′‐Deoxyuridine Derivatives by the Copper(I)‐Catalyzed AlkyneAzide ‘Click’ Cycloaddition
Authors: Seela Frank , Sirivolu Venkata Ramana
Published: March 2007

Oligonucleotides containing the 5‐substituted 2′‐deoxyuridines 1b or 1d bearing side chains with terminal CC bonds are described, and their duplex stability is compared with oligonucleotides containing the 5‐alkynyl compounds 1a or 1c with only one nonterminal CC bond in the side chain. For this, 5‐iodo‐2′‐deoxyuridine (3) and diynes or alkynes were employed as starting materials in the Sonogashira cross‐coupling reaction (Scheme 1). Phosphoramidites 2b–d were prepared (Scheme 3) and used as building blocks in solid‐phase synthesis. Tm Measurements demonstrated that DNA duplexes containing the octa‐1,7‐diynyl side chain or a diprop‐2‐ynyl ether residue, i.e., containing 1b or 1d, are more stable than those containing only one triple bond, i.e., 1a or 1c (Table 3). The diyne‐modified nucleosides were employed in further functionalization reactions by using the protocol of the CuI‐catalyzed Huisgen–Meldal–Sharpless [2+3] cycloaddition (‘click chemistry’) (Scheme 2). An aliphatic azide, i. e., 3′‐azido‐3′‐deoxythymidine (AZT; 4), as well as the aromatic azido compound 5 were linked to the terminal alkyne group resulting in 1H‐1,2,3‐triazole‐modified derivatives 6 and 7, respectively (Scheme 2), of which 6 forms a stable duplex DNA (Table 3). The Husigen–Meldal–Sharpless cycloaddition was also performed with oligonucleotides (Schemes 4 and 5).
Shared near neighbours neural network model: a debris flow warning system
Authors: Chang Fi‐John , Tseng Kuo‐Yuan , Chaves Paulo
Published: March 2007

The main purpose of this study is to develop a new type of artificial neural network based model for constructing a debris flow warning system. The Chen‐Eu‐Lan river basin, which is located in Central Taiwan, is assigned as the study area. The creek is one of the most well‐known debris flow areas where several damaging debris flows have been reported in the last two decades. The hydrological and geological data, which might have great influence on the occurrence of debris flows, are first collected and analysed, then, the shared near neighbours neural network (SNN + NN) is presented to construct the debris flow warning system for the watershed. SNN is an unsupervised learning method that has the advantage of dealing with non‐globular clusters, besides presenting computational efficiency. By using SNN, the compiled hydro‐geological data set can easily and meaningfully be clustered into several categories. These categories can then be identified as ‘occurrence’ or ‘no‐occurrence’ of debris flows. To improve the effectiveness of the debris flow warning system, a neural network framework is designed to connect all the clusters produced by the SNN method, whereas the connected weights of the network are adjusted through a supervised learning method. This framework is used and its applicability and practicability for debris flow warning are investigated. The results demonstrate that the proposed SNN + NN model is an efficient and accurate tool for the development of a debris flow warning system. Copyright © 2007 John Wiley & Sons, Ltd.
Hillslope hydrology and wetland response of two small zero‐order boreal catchments on the Precambrian Shield
Authors: Frisbee M. D. , Allan C. J. , Thomasson M. J. , Mackereth R.
Published: March 2007

Two Precambrian Shield zero‐order catchments were monitored from January 2003 to July 2004 to characterize their hydrological and biogeochemical characteristics prior to a forest management experiment. Hydrometric observations were used to examine temporal trends in hillslope‐wetland connectivity and the hillslope runoff processes that control wetland event response. The hillslope groundwater flux from the longer transect (E1) was continuous throughout the study period. Groundwater fluxes from a shorter and steeper hillslope (E0) were intermittent during the study period. Large depression storage elements (termed micro‐basins) located on the upper hillslope of the E1 catchment appeared to be at least partly responsible for the observed rapid wetland runoff responses. These micro‐basins were hydrologically connected to a downslope wetland by a subsurface channel of glacial cobbles that functioned as a macropore channel during episodic runoff events. The runoff response from the hilltop micro‐basins is controlled by antecedent water table position and water is quickly piped to the wetland fringe through the cobble channel during high water table conditions. During periods of low water table position, seepage along the bedrock–soil interface from the hilltop micro‐basin and other hillslopes maintained hillslope–wetland connectivity. The micro‐basins create a dynamic variable source‐area runoff system where the contributing area expands downslope during episodic runoff events. The micro‐basins occupied 30% of the E1 catchment and are a common feature on the Precambrian Shield. Copyright © 2007 John Wiley & Sons, Ltd.
Grb2‐SH3 ligand inhibits the growth of HER2+ cancer cells and has antitumor effects in human cancer xenografts alone and in combination with docetaxel
Authors: Gril Brunilde , Vidal Michel , Assayag Franck , Poupon Marie‐France , Liu Wang‐Qing , Garbay Christiane
Published: March 2007

HER2 represents an important signaling pathway in breast and other cancers. Herceptin has demonstrated clinical activity, but resistance is common. Thus, new therapeutic approaches to the HER2 pathway are needed. Grb2 is an adaptor protein involved in Ras‐dependent signaling induced by HER2 receptors. A specific Grb2‐SH3 ligand, designed and synthesized in our laboratory, called peptidimer‐c, inhibited colony formation in HER2 overexpressing SKBr3 cancer cells. Combined treatment of peptidimer‐c with docetaxel further inhibited both colony formation and tumor cell survival compared to docetaxel treatment alone. Efficacy of this combined treatment was correlated with a reduction in the phosphorylation of MAPK and AKT. Finally, peptidimer‐c reduced the growth of a HER2+ human breast cancer (BK111) xenograft in nude mice and potentiated the antitumor effect of docetaxel in a HER2+ hormone‐independent human prostate adenocarcinoma (PAC120 HID28) xenograft. These results validate Grb2 as a new target for the HER2 pathway. © 2007 Wiley‐Liss, Inc.
Cytoplasmic accumulation of connexin32 protein enhances motility and metastatic ability of human hepatoma cells in vitro and in vivo
Authors: Li Qingchang , Omori Yasufumi , Nishikawa Yuji , Yoshioka Toshiaki , Yamamoto Youhei , Enomoto Katsuhiko
Published: March 2007

Connexins have long been believed to suppress tumour development during carcinogenesis by exerting gap junctional intercellular communication (GJIC). Although GJIC is abrogated in hepatocellular carcinoma (HCC), connexin32 (Cx32) protein tends to remain expressed in cytoplasm, but not in cell–cell contact areas; thus, it is incapable of forming gap junctions. Hypothesising that cytoplasmic Cx32 protein that has accumulated in HCC should have its proper functions, which are independent of GJIC, we established an inducible expression system of Cx32 in human HuH7 HCC cells, which were unable to support the formation of Cx32‐mediated gap junctions, so that Cx32 protein could be overexpressed by doxycycline (Dox) withdrawal. Although the established clone HuH7 Tet‐off Cx32 cells exhibited a 4‐fold increase in Cx32 expression after Dox withdrawal, none of them were dye‐coupled, and Cx32 protein was retained in the Golgi apparatus. However, the proliferation rate of the HuH7 Tet‐off Cx32 cells was significantly higher in the Dox‐free medium than in the Dox‐supplemented one. Transwell assays also revealed that Dox withdrawal enhanced serum‐stimulated motility and invasiveness into Matrigel of the HuH7 Tet‐off Cx32 cells. Furthermore, when HuH7 Tet‐off Cx32 cells were xenografted into the liver of SCID mice, only the mice to which no Dox was administered developed metastatic lesions, indicating that overexpression of cytoplasmic Cx32 protein induced metastasis of HuH7 cells. Our results suggest that, while Cx32‐mediated GJIC suppresses the development of HCCs, cytoplasmic Cx32 protein exerts effects favourable for HCC progression, such as invasion and metastasis, once the cells have acquired a malignant phenotype. © 2007 Wiley‐Liss, Inc.
Stock option backdating bedlam
Authors: Ciesielski Jack T. , Weirich Thomas R.
Published: March 2007

Now that the dust has settled a bit, we take a closer‐look at the recent stock option backdating scandal. Stock option plans have usually been justified by saying they aligned management's interests with those of shareholders. But the authors point out that by backdating stock options, the board of directors weakens the bond between top management and shareholders.

What caused this latest financial scandal? Was it one more example of unbridled executive greed? Or was it mostly sloppy recordkeeping? This article examines the issues, and the future implications for companies. © 2007 Wiley Periodicals, Inc.
Rebalancing the accounting profession
Authors: Sharman Paul A.
Published: March 2007

An alarming shift of balance has occurred in the accounting profession—a shift from a focus on work that facilitates business and economic development toward an emphasis on satisfying regulatory requirements. One result is that accountants are increasingly being trained to satisfy these regulatory requirements instead of being provided with the skills they need to become financial professionals who contribute as performance advisors and strategic business partners. This article presents steps needed to rebalance the accounting profession. © 2007 Wiley Periodicals, Inc.
Effects of prolyl hydroxylase inhibitors on adipogenesis and hypoxia inducible factor 1 alpha levels under normoxic conditions
Authors: Floyd Z. Elizabeth , Kilroy Gail , Wu Xiying , Gimble Jeffrey M.
Published: March 2007

Adipocyte function is highly regulated in response to changing oxygen levels and physiological regulation of adipocyte formation involves factors originally identified as hypoxia‐responsive proteins. Inhibition of adipogenesis at low oxygen tension is associated with activation of hypoxia inducible factor‐1 alpha (HIF‐1α), a transcription factor essential for cellular responses to decreased oxygen levels whose activity is regulated by prolyl hydroxylase (PHD) enzymes. However, HIF‐1α RNA expression has been detected during the initial stages of adipocyte formation under aerobic conditions, suggesting a physiological role for HIF‐1α during adipogenesis under a range of oxygen levels. Here we investigated the expression of HIF‐1α during adipogenesis using the murine 3T3‐L1 adipocyte model. Our results indicate the tissue‐specific form of HIF‐1α is upregulated during adipogenesis with maximal levels obtained within the first 24 h after induction. The increase in HIF‐1α l.1 gene expression corresponds to increased nuclear HIF‐1α protein, which gradually declines throughout adipogenesis under aerobic conditions. Each of the three HIF prolyl hydroxylases involved in regulating HIF‐1α stability is expressed during adipogenesis. The prolyl hydroxylase domain 1 (PHD1) isoform of the HIF prolyl hydroxylases is expressed in early adipogenesis and the PHD2 and PHD3 isoforms are expressed during late adipogenesis. Pharmacological inhibition of PHD activity during the initial stages of adipogenesis abrogates the formation of adipocytes and inhibits gene expression of each of the PHD. However, inhibition of PHD activity does not consistently regulate HIF‐1α l.1 expression or HIF‐1α protein levels, suggesting that hydroxylation‐independent mechanisms are involved in regulating HIF‐1α expression in adipocytes under aerobic conditions. J. Cell. Biochem. 101: 1545–1557, 2007. © 2007 Wiley‐Liss, Inc.