bluuebunny/crossref_metadata_2025 huggingface dataset:
The correlation energy in the random phase approximation: Intermolecular forces between closed-shell systems
Authors: Szabo Attila , Ostlund Neil S.
Published: February 2003

A new expression for the correlation energy within the random phase approximation (RPA) is presented. It has the following properties: it is (1) size consistent, (2) invariant to unitary transformations of degenerate orbitals, (3) correct to second order in perturbation theory, and (4) when applied to a supermolecule comprised of two interacting closed-shells, it describes the dispersive part of the interaction at the coupled Hartree–Fock (HF) level, i.e., the van der Waals’ coefficient extracted from its long-range behavior is identical to that obtained from the Casimir–Polder expression using the dynamic coupled Hartree–Fock polarizabilities of the isolated systems. This expression, which requires only particle–hole two-electron integrals for its evaluation, is expected to yield considerably more accurate potential energy curves between closed-shell systems than second-order Moller–Plesset perturbation theory which, as is shown, describes dispersion forces at the less accurate uncoupled HF level. In addition, since it is shown how this RPA correlation energy can be obtained from the zeroth iteration of a self-consistent RPA procedure such as that of McKoy and co-workers, our result can be systematically improved. Finally, illustrative calculations of He and (He)2 are presented.
Information theory, distance matrix, and molecular branching
Authors: Bonchev D. , Trinajstić N.
Published: February 2003

Information theory was used in defining several measures of the topological properties of molecules, namely, information for adjacency, incidence, polynomial coefficients of the adjacency matrix, and for distances of molecular graphs. The latter was found to have a greater ability for discrimination between structural isomers than all known topological indices and to be a very appropriate measure of branching. All the quantities related to the distance matrix (two information measures, the Weiner number and the largest eigenvalue of the characteristic polynomial) were found to reflect in the same way the main features of molecular branching. On this basis, as well as on the basis of general expressions for information content and Wiener number derived for tree graphs, the essence of molecular branching was expressed in a number of rules. It was shown that these theoretical rules on branching are in agreement with the intuitive understanding of branching and are reflected in a large number of molecular properties.
Antimony (III) orbital population analysis using antimony-121 Mössbauer data
Authors: Hedges Sheila W. , Bowen L. H.
Published: February 2003

A method of orbital population analysis which utilizes both Mössbauer isomers shifts and quadrupole coupling constants has been developed for Sb(III) compounds. A linear relationship between the isomer shift δ and number of s electrons ns is inadequate for Sb(III) and an empirical quadratic equation has been developed. The electron population along the Sb–L bond σL is calculated for a number of unsymmetric stibines of the type R2R′Sb and RR′2Sb, where R=phenyl and R′=methyl, vinyl, allyl, and propyl, as well as for some Sb(III) oxides.
Photochemical separation of europium from lanthanide mixtures in aqueous solution
Authors: Donohue Terence
Published: February 2003

Equimolar mixtures of binary or ternary combinations of tanthanides were studied with several photolytic sources. The solutions were photolyzed until more than 90% of Eu3+ was reduced. This is the first such study reported.(AIP)
Stability and relative stability in reactive systems far from equilibrium. II. Kinetic analysis of relative stability of multiple stationary states
Authors: Procaccia Itamar , Ross John
Published: February 2003

We analyze the relative stability of multiple stationary states in chemically reactive systems far from equilibrium from a stochastic point of view. We take fluctuations into account and invoke the concept of mean first passage time, which gives a measure for the tendency of transition from one stationary state to the other. For one variable (and effectively one-variable) systems we find analytic results that are in agreement with those of relative stability found in the previous article (Paper I) with a thermodynamic analysis. The extension of the analysis to multivariable systems is indicated. We show that in the thermodynamic limit relative stability is determined solely by the properties of the stationary states.
Rates of OH radical reactions. III. The reaction OH+C2H4+M at 296 °K
Authors: Overend Ralph , Paraskevopoulos George
Published: February 2003

Absolute rate constants for the reaction OH+C2H4+M were determined at 296 °K over a pressure range of various third bodies, M, using the flash-photolysis resonance absorption technique. The rate constant was found to depend on the pressure and the nature of the third body; H2O, SF6, and CF4 were found to be efficient third bodies, while He was found to be relatively inefficient. The limiting value of kII at high pressure, kII∞, was found to be kII∞=6±1×1012 cm3 mol−1 s−1. This value is recommended for use in modeling of tropospheric processes.
Interference effects in rotational state distributions: Propensity and inverse propensity
Authors: McCurdy Clyde W. , Miller William H.
Published: February 2003

Semiclassical scattering theory has been used to investigate interference effects in rotational state distributions for inelastic atom–diatom collisions. The Δj=even selection rule for homonuclear molecules is seen semiclassically to be an interference effect, and when this symmetry is weakly broken—i.e., an ’’almost homonuclear’’ molecule, one for which the odd anisotropy is much smaller than the even anisotropy—the interference persists in the form of a propensity rule, σ (odd Δj) ≪σ (even Δj). If the odd anisotropy is sufficiently large, however, one can see an inversion of the normal propensity, i.e., it can happen that σ (odd Δj) ≳σ (even Δj). It is suggested that rotationally state-selected experiments which resolve this interference structure would be an extremely sensitive measure of the anisotropy in the interaction potential.
The binding energy of Li3
Authors: Inglesfield J. E.
Published: February 2003

The Wigner–Seitz method provides a good effective potential, including correlation effects, for alkali molecules as well as metals. Here it is used with the matching Green function method to calculate the binding energy of linear Li3. This turns out to be −0.068 a.u. per molecule, relative to free atoms, at an equilibrium internuclear separation of 5.1 a.u., compared with −0.051 a.u. for the binding energy of Li2 obtained in a similar calculation.
Nematic ordering in the lattice model with attractive isotropic interaction
Authors: Stecki J.
Published: February 2003

The athermal lattice model in which elongated rigid molecules are simulated by rows of consecutive sites is generalized so as to include an attractive segment–segment interaction energy—ε. Thus a distinction is made between a liquidlike phase and a supercritical gas phase. The model is solved in the Bethe–di Marzio and in the quasichemical approximation. The presence of such an attractive interaction leads to a reasonable p,T diagram of state provided r=4 or 5 in three or six dimensions. For longer rods, only the phase transition from the supercritical gas with very large volume changes is obtained already for r?6.
Microwave optical double resonance spectrum of NH2. III. 1H and 14N hyperfine coupling constants and spin rotation constants in X̃ 2B1
Authors: Cook J. M. , Hills G. W. , Curl R. F.
Published: February 2003

Over 200 microwave transitions involving 31 rotational levels in the X̃ 2B1 state%of NH2 have been observed using microwave optical double resonance. The majorityh of the observed lines are magnet magnetic dipole allowed transitions between the two spin components of a given rotational state, J=N−1/2←N+1/2, Nkakc The observed lines have been analyzed to yield accurate values for the spin rotation (including those describing the effects of centrifugal distortion), 14N hyperfine and 1H hyperfine constants. The three spin rotation constants are determnied to be As=−9267.8 (1.4), Bs=−1353.9 (0.5), and Cs=12.0(0.3), where all constants are in MHz and the quoted error in parentheses is three standard deviations. The five centrifugal distortion constants for the spin rotation interaction derived are (in a notation analogous to Watson’s rotational centrifugal distortion constants) ΔsN=−0.312(0.007), ΔSk=−33.9 (0.6), ΔSNK=3.51(0.11), δsN=−0.155 (0.004), and δsK=−0.480 (0.077). The 14N hyperfine constants determined in this analysis are (O)I=28.2 (0.4), (aa)I=−42.8 (1.3), (bb)I=−44.7(1.0), and (cc)I=87.5 (0.5). The 1H hyperfine constants are (O)I=−67.2(0.4), (aa)I=18.6(1.3), (bb)I =−13.4(0.9), and (cc)I=−5.2(0.6). Quadrupole constants for 14N are also determinable from the data as (aa)Q=0.1 (1.3), (bb)Q =−1.6(1.1), and (cc)Q=1.5(0.6).
Short-range correlations and the effective orientational energy in liquid crystals
Authors: Wulf A.
Published: February 2003

Experiment and theory have shown that the orientational free energy of nematic liquid crystals contains both a translational entropy term and an orientational energy term, which are of the same order of magnitude. It has been proposed recently that the energy term is due to the total attractive interaction energy, which is modulated by order-dependent radial correlations between the rodlike molecular cores. In this paper we confirm this proposal by a calculation of the pair correlations in a fluid of short rods. It turns out that the only point of some difficulty is to explain the relatively small ’’experimental’’ value of the orientational energy −W2 η2/2, where η=orientational order parameter, for the length (l) to diameter (d) ratios common in liquid crystal molecules (l/d≳3). Our results indicate that to get reasonable values of W2/W0 (−W0/2=internal energy for η=0), for l/d≳3/2, it is important to take account of short-range orientational order. Also, there is the suggestion that the dispersion energy between the rodlike molecules varies more slowly than 1/R6 at short distances R. The calculation of the pair correlation function in this paper is based on the Ornstein–Zernike (OZ) equation. The orientational order and the direct correlation function (DCF) are assumed known, and the resulting OZ equation for the correlation function is put into a simple variational form. (A simplified version of the DCF suggested by Pynn is used.) The variational problem is solved approximately by using a trial correlation function which emphasizes the small-distance correlations.
X-ray diffraction pattern and models of liquid benzene
Authors: Narten A. H.
Published: February 2003

X-ray diffraction data for liquid benzene at 25°C are analyzed using scattering factors for C–H groups rather than for C and H atoms. This new approach permits the unique extraction of structure and correlation functions for carbon–carbon interactions from a single experiment. The data are used to find parameters for a model (RISM) of liquid benzene which permits calculation of all intermolecular atom pair correlation functions. The predominant arrangement in the liquid is one in which pairs of molecules fit together like six-toothed bevel gear wheels whose axes are almost at right angles.
Isotopic effects on the electronic properties of H2O and D2O in the vacuum uv
Authors: Heller J. M. , Birkhoff R. D. , Painter L. R.
Published: February 2003

Optical and dielectric functions of liquid H2O and D2O at 25 °C were obtained in the 2–9.2 eV region of photon energy. The reflectance was measured for several angles of incidence at a liquid–semicylindrical-window interface. The refractive index n and absorption coefficient k were obtained by a least-squares fit of calculated to experimental reflectance. The principle difference observed was the contraction of the D2O spectra due to the mass effect of the heavier isotope.
Oscillations and runaway states in a closed illuminated system
Authors: DelleDonne M. , Ortoleva P.
Published: February 2003

Using a model reaction mechanism we show that in a closed illuminated system one may find limit cycle oscillations and runaway states involving unbounded increase in temperature (until new physical processes become important). The model is a simplification of that used by Prigogine and Lefever to demonstrate oscillations in an open system. For our model we show that there exists an upper and lower bifurcation point for oscillation and that in the vicinity of parameter values (light intensities) for which the runaway states may occur the typical Hopf bifurcation is masked. Under conditions of multiple time scales the oscillation consists of a sequence of short time scale ’’explosions’’. The model presents itself as an ideal system for statistical mechanical studies because when the optical pathlength is short the system may be treated as a homogeneous ensemble, unlike earlier open model systems.
The photoelectron and far-ultraviolet absorption spectra of simple oximes
Authors: Dargelos A. , Sandorfy C.
Published: February 2003

The HeI photoelectron and far ultraviolet absorption spectra of formaldoxime (CH2=N–OH) and three other simple nonconjugated oximes are reported and compared to those of simple imines. Contrary to imines the lowest ionization potential seems to be related to the π orbital although this assignment must be considered tentative. In the uv spectrum the π*←n, π*←π and 3s←π bands are readily identified.
Laser excited infrared fluorescence in COF2: Equilibration and relaxation of the C=O and C–F stretching modes
Authors: Casleton Kent H. , Flynn George W.
Published: February 2003

Over 30 different CO2 laser lines have been found to produce strong laser induced fluorescence at λ=5 μ from the ν1 (C=O stretch) and 2ν2 (C–F stretch) states in COF2. The observed fluorescence is of two distinct types consistent with two different primary pumping mechanisms: (1) laser pumping 0→ν2 followed by collisional filling of 2ν2 via excited state–excited state collisions, and (2) direct laser pumping of ambient molecules in ν2 via the ν2→2ν2 transition. The ν1 and ν2 manifolds reach vibrational steady state within 30 gas kinetic collisions, while approximately 500 collisions are required to relax this localized energy to the remaining vibrational modes.
Photodissociation of negative ions formed in CO2 and CO2/O2 mixtures
Authors: Vestal M. L. , Mauclaire G. H.
Published: February 2003

A new tandem quadrupole mass spectrometer, developed explicitly for photodissociation experiments, has been used to study the photodissociation reactions of CO3− and CO4− ions formed in CO2 and CO2/O2 mixtures at pressures between 0.05 and 1.4 torr. These measurements have been accomplished at six discrete photon energies between 2.1–4.1 eV using the intense lines from a 200 W Hg lamp with a small monochromater, and more detailed measurements were carried out between 1.8–2.1 eV using a flash-lamp pumped tunable dye laser. The apparent photodissociation cross section for the reaction CO3−→O−+CO2 was measured as a function of ion source pressure at several wavelengths. The results are interpreted as indicating that CO3− ions produced by the three-body association reaction, O−+2CO2→CO3−+CO2 are initially formed in an electronically excited state and are rather slowly relaxed to the ground state by further collisions with CO2. The measured relaxation rate constant is approximately 5×10−14 cm3/sec.
Comment on ’’Probability of escaping neutralization when the mobility is field dependent’’
Authors: Baird James K. , Anderson Verner E. , Rice Stephen A.
Published: February 2003

The field dependence of the electron mobility in dielectric liquids is discussed.(AIP)
Electron escape depths of organic solids
Authors: Hino Shojun , Sato Naoki , Inokuchi Hiroo
Published: February 2003

Low energy electron-attenuation lengths (escape depths) of organic solids̄naphthacene, coronene, violanthrene A, and Cu-phthalocyanine have been determined by the successive change of film thickness. Transmitted electron current decreases exponentially in accordance with increase of the film thickness in thin film region. From this exponential decrease, we have estimated the electron-attenuation lengths. The electron-attenuation lengths vary in a wide range from 1.3 nm (violanthrene A) to 61 nm (coronene).
Vibronic structure in the ’’metallic’’ reflection band of the TCNQ crystal
Authors: Philpott M. R. , Grant P. M. , Syassen K. , Turlet J-M.
Published: February 2003

Polarized reflection spectra off the (010) face of the first singlet transition of crystalline tetracyanoquinodimethane (TCNQ) have been measured at room and liquid helium temperatures. The spectrum consists of a massive block of high reflectivity, corresponding to a stop band 1.4 eV wide, with well defined edges at 2.8 and 4.2 eV. The reflectivity of the long wavelength edge undergoes a large increase upon cooling, and vibrational structure appears between 2.8 and 3.1 eV due to freezing out of powerful polariton scatterers, the intramolecular vibrations. All structure is assoicated with volume polaritons since it is not shifted when the crystal is coated with a layer of frozen gas. The complex dielectric function, calculated by a Kramers–Kronig transformation, shows two regions where the real part ε1 is negative. The spectra provide a test of the basic notions of strong vibronic coupling in molecular crystals. Polariton scattering by lattice phonons is weak, whereas scattering by intramolecular modes is much stronger.
NMR study of angular momentum relaxation in fluids. I. Compressed CF4
Authors: Finney R. J. , Wolfe M. , Jonas J.
Published: February 2003

Angular momentum relaxation has been studied in the spherical top molecule of CF4 from the dense to dilute fluid region. For this purpose the NMR 19F spin-lattice relaxation times, T1, have been measured in CF4 as a function of pressure and temperature over the wide density range 0.28⩽ρ/ρc⩽2.48 and the temperature range 1.2⩽T/Tc⩽1.64. Since spin-rotation interactions provide the dominant relaxation mechanism for the fluorine nuclei, the analysis of the T1 data yields the angular momentum correlation time, τJ. Interpretation of the experimental τJ data in terms of the rough hard sphere model of liquids gives the hard core diameters for CF4 and its temperature dependence. In the dense fluid region for ρ⩾2ρc the rough hard sphere model proposed by Chandler is valid and the calculated parameter a (T) =τE/τJ, where τE is the Enskog relaxation time is weakly temperature dependent and independent of density. This parameter a (T) is a measure of the roughness of the hard spheres indicating how efficiently angular momentum is transferred during a collision. At intermediate and low densities the parameter a (T) increases with decreasing density as a result of less effective screening of the attractive forces due to harsh short-ranged repulsive forces. To account for the attractive forces we propose a modified hard sphere model based on optimized cluster theory with the parameter b (T,ρ) =a (T) exp[CL(σ)], where a (T) is the limiting value of τE/τJ for ρ≳2ρc, and CL(r) is the renormalized intermolecular potential based on the Lennard-Jones potential for CF4. By including the effect of the attractive forces the modified rough hard sphere model accounts well for the experimental a (T) behavior over the entire density range.
Actin Dynamics Is Controlled by a Casein Kinase II and Phosphatase 2C Interplay onToxoplasma gondiiToxofilin
Authors: Delorme Violaine , Cayla Xavier , Faure Grazyna , Garcia Alphonse , Tardieux Isabelle
Published: February 2003

Actin polymerization in Apicomplexa protozoa is central to parasite motility and host cell invasion. Toxofilin has been characterized as a protein that sequesters actin monomers and caps actin filaments in Toxoplasma gondii. Herein, we show that Toxofilin properties in vivo as in vitro depend on its phosphorylation. We identify a novel parasitic type 2C phosphatase that binds the Toxofilin/G-actin complex and a casein kinase II-like activity in the cytosol, both of which modulate the phosphorylation status of Toxofilin serine53. The interplay of these two molecules controls Toxofilin binding of G-actin as well as actin dynamics in vivo. Such functional interactions should play a major role in actin sequestration, a central feature of actin dynamics in Apicomplexa that underlies the spectacular speed and nature of parasite gliding motility.
The Protein Tyrosine Phosphatase Pez Is a Major Phosphatase of Adherens Junctions and Dephosphorylates β-Catenin
Authors: Wadham Carol , Gamble Jennifer R , Vadas Mathew A , Khew-Goodall Yeesim
Published: February 2003

Cell-cell adhesion regulates processes important in embryonal development, normal physiology, and cancer progression. It is regulated by various mechanisms including tyrosine phosphorylation. We have previously shown that the protein tyrosine phosphatase Pez is concentrated at intercellular junctions in confluent, quiescent monolayers but is nuclear in cells lacking cell-cell contacts. We show here with an epithelial cell model that Pez localizes to the adherens junctions in confluent monolayers. A truncation mutant lacking the catalytic domain acts as a dominant negative mutant to upregulate tyrosine phosphorylation at adherens junctions. We identified β-catenin, a component of adherens junctions, as a substrate of Pez by a “substrate trapping” approach and by in vitro dephosphorylation with recombinant Pez. Consistent with this, ectopic expression of the dominant negative mutant caused an increase in tyrosine phosphorylation of β-catenin, demonstrating that Pez regulates the level of tyrosine phosphorylation of adherens junction proteins, including β-catenin. Increased tyrosine phosphorylation of adherens junction proteins has been shown to decrease cell-cell adhesion, promoting cell migration as a result. Accordingly, the dominant negative Pez mutant enhanced cell motility in an in vitro “wound” assay. This suggests that Pez is also a regulator of cell motility, most likely through its action on cell-cell adhesion.
Wrapping up BLAST and other applications for use on Unix clusters
Authors: Hokamp Karsten , Shields Denis C. , Wolfe Kenneth H. , Caffrey Daniel R.
Published: February 2003

Summary: We have developed two programs that speed up common bioinformatic applications by spreading them across a UNIX cluster.(1) BLAST.pm, a new module for the ‘MOLLUSC’ package. (2) WRAPID, a simple tool for parallelizing large numbers of small instances of programs such as BLAST, FASTA and CLUSTALW.

Availability: The packages were developed in Perl on a 20-node Linux cluster and are provided together with a configuration script and documentation. They can be freely downloaded from http://wolfe.gen.tcd.ie/wrapper

Contact: daniel_r_caffrey@cambridge.pfizer.comkarsten@oscar.gen.tcd.ie

* These authors contributed equally to this work.

† Current Address: Pfizer Discovery Technology Center, 620 Memorial Drive, Cambridge, MA 02139, USA.
Influencing and negotiating skills: some research and reflections – Part I: influencing strategies and styles
Authors: Manning Tony , Robertson Bob
Published: February 2003

Examines the connection between influencing and negotiation. Using data collected from self‐assessment instruments developed by them, the authors argue that it is useful to see negotiation as one type of influencing. The article is in two parts. This first part concentrates on influencing. It looks at the six strategies that people at work actually use in their attempts to influence others. These strategies are used in combination and this makes it possible to identify four types of influencer or styles of influence. It is stressed that styles of influence are context specific. The findings raise questions about training in these areas and have implications for how this is undertaken. They also raise questions about what constitutes managerial effectiveness in these areas.
The socio‐economics of niche market creation
Authors: Dimara Efthalia , Petrou Anastasia , Skuras Dimitris
Published: February 2003

Farmers’ decision to adopt organic cultivation and create niche markets is their response to the changing notions of quality and the gradual abandonment of the productivist logic in agriculture. This decision is analyzed within a multi‐level social ecological context designed to account simultaneously for all facets/parts of the farmer's decision‐making process. Social ecology provides a contextual platform conceptualizing global‐regional‐local relationships within which niche markets for food products are created. Emphasis is placed on farmers’ perception of the “environment” within which they have to decide on their participation in a policy scheme. Elements of the macro (global), meso (national/regional) and micro (farm household) “environmental” levels, affect the farmer's decision to adopt organic cultivation. Accordingly, a decision‐making tree reflecting how farmers perceive that environment and form their decisions is constructed, and statistical models test the impact of factors in the global‐regional‐local levels on this decision‐making process.
Purchasing and supply chain management practices in Botswana
Authors: Msimangira Kabossa A.B.
Published: February 2003

Discusses supply chain management practices, with emphasis on purchasing, in Botswana (a developing country). Focuses on problems facing business operations and how to improve the situation. Presents the views of purchasing personnel from public and private organizations and of students taking purchasing and supply chain management courses. Discovers that purchasing has not been recognized as a profession, which has led to lack of motivation in purchasing sections’ personnel. Further, purchasing policies on external relationships and image are non‐existent in most organizations. Claims that managers need to change their thinking about the purchasing and supply function – to see it as strategic and not clerical; and purchasing and supplies personnel require training in supply chain management.
Complementors: fellow travellers in contract manufacture
Authors: Noonan John , Wallace Michael
Published: February 2003

Two major markets exist in manufacturing and both are rapidly changing. On the one hand, there are the traditional original equipment manufacturers (OEMs) who build their own end‐user products. Fewer and fewer of the vital components within the products sold are original. Instead, a structured network of supplier companies builds the components. These contract manufacturers may have a number of OEMs as clients and keep their manufacturing processes running full‐time by shifting jobs back and forth among client’s orders as demand requires. In recent years, more and more is required of the contract manufacturer. As well as working with traditional external forces the contract manufacturer now has to contend with the concept of complementors. This paper describes research into the concept of the complementor and proposes the complementor impact model for contract manufacturers. This new model demonstrates how contract manufacturers may capitalise relationships with fellow complementors. In doing so they themselves become superior complementors.
Furin Processing and Proteolytic Activation of Semliki Forest Virus
Authors: Zhang Xinyong , Fugère Martin , Day Robert , Kielian Margaret
Published: February 2003

The alphavirus Semliki Forest virus (SFV) infects cells via a low-pH-dependent membrane fusion reaction mediated by the E1 envelope protein. Fusion is regulated by the interaction of E1 with the receptor-binding protein E2. E2 is synthesized as a precursor termed “p62,” which forms a stable heterodimer with E1 and is processed late in the secretory pathway by a cellular furin-like protease. Once processing to E2 occurs, the E1/E2 heterodimer is destabilized so that it is more readily dissociated by exposure to low pH, allowing fusion and infection. We have used FD11 cells, a furin-deficient CHO cell line, to characterize the processing of p62 and its role in the control of virus fusion and infection. p62 was not cleaved in FD11 cells and cleavage was restored in FD11 cell transfectants expressing human furin. Studies of unprocessed virus produced in FD11 cells (wt/p62) demonstrated that the p62 protein was efficiently cleaved by purified furin in vitro, without requiring prior exposure to low pH. wt/p62 virus particles were also processed during their endocytic uptake in furin-containing cells, resulting in more efficient virus infection. wt/p62 virus was compared with mutant L, in which p62 cleavage was blocked by mutation of the furin-recognition motif. wt/p62 and mutant L had similar fusion properties, requiring a much lower pH than control virus to trigger fusion and fusogenic E1 conformational changes. However, the in vivo infectivity of mutant L was more strongly inhibited than that of wt/p62, due to additional effects of the mutation on virus-cell binding.
Restriction of Human Immunodeficiency Virus Type 1 Rev Function in Murine A9 Cells Involves the Rev C-Terminal Domain
Authors: Marques Sandra M. P. , Veyrune Jean-Luc , Shukla Ram R. , Kumar Ajit
Published: February 2003

The human immunodeficiency virus type 1 (HIV-1) Rev and human T-cell leukemia virus type 1 (HTLV-1) Rex proteins are essential for the expression of viral structural proteins and productive infection. Both contain a nuclear export signal (NES) in their C-terminal domain and a nuclear localization signal (NLS) in their N-terminal domain. The NES and NLS are necessary for shuttling between nucleus and cytoplasm and are therefore indispensable for the transport of unspliced and singly spliced viral transcripts. HIV-1 Rev function is restricted in A9 cells, a murine fibroblast cell line, whereas HTLV-1 Rex is functional in these cells. Immunofluorescence studies with RevGFP fusion protein demonstrate normal import and export of Rev in A9 cells. To ascertain which domains of Rev are necessary for the restriction of Rev function in A9 cells, we studied a chimeric construct in which the NES domain of Rev was exchanged with Rex C-terminal amino acids 79 to 95, the Rev1-79/Rex79-95 chimera, which restored Rev function in A9 cells. In addition, overexpression of a truncated Rev containing the Rev C-terminal domain in the presence of wild-type Rev, led to restoration of Rev function in A9 cells. These results suggest that the C-terminal domain of HIV-1 Rev plays an important role in restricting Rev function in murine cells.
Emergence of clonal cytogenetic abnormalities in Ph−cells in some CML patients in cytogenetic remission to imatinib but restoration of polyclonal hematopoiesis in the majority
Authors: Bumm Thomas , Müller Christel , Al-Ali Haifa-Kathrin , Krohn Knut , Shepherd Patricia , Schmidt Erika , Leiblein Sabine , Franke Christina , Hennig Evelin , Friedrich Thomas , Krahl Reiner , Niederwieser Dietger , Deininger Michael W. N.
Published: February 2003

Chronic myelogenous leukemia (CML) is characterized by the presence of a Bcr-Abl fusion protein with deregulated tyrosine kinase activity that is required for maintaining the malignant phenotype. Imatinib, a selective inhibitor ofBcr-Abl, induces major cytogenetic remission (MCR) or complete cytogenetic remission (CCR) in the majority of patients with CML in first chronic phase. However, thorough re-evaluation of cytogenetics in a cohort of patients in MCR or CCR demonstrated clonal karyotypic abnormalities in more than 10% of cases, some of which were clinically associated with a myelodysplastic syndrome (MDS). Further analysis identified previous exposure to cytarabine and idarubicin as significant risk factors for the subsequent occurrence of abnormalities in Philadelphia chromosome–negative (Ph−) cells. To investigate if cytogenetically normal but clonal hematopoiesis might be present in other patients in cytogenetic remission, we studied X-chromosome inactivation as a marker of clonality by polymerase chain reaction analysis of the human androgen receptor (HUMARA). We find that imatinib restores a polyclonal pattern in most patients in CCR and MCR. Nonetheless, our results are consistent with the notion that targeted therapy of CML with imatinib favors the manifestation of Ph− clonal disorders in some patients. They indicate that patients on imatinib should be followed with conventional cytogenetics, even after induction of CCR.
The 4G5G polymorphism in the gene for PAI-1 and the circadian oscillation of plasma PAI-1
Authors: van der Bom Johanna G. , Bots Michiel L. , Haverkate Frits , Kluft Cornelis , Grobbee Diederick E.
Published: February 2003

Plasminogen activator inhibitor type I (PAI-1) antigen concentrations follow a circadian oscillation peaking in the morning. Some individuals show no apparent circadian rhythm, while others show up to a 10-fold variation in PAI-1 over 24 hours. Results from experimental studies suggest that a polymorphism in the promoter of the gene for PAI-1 (4G5G) directly influences the circadian expression of the PAI-1 gene. We studied whether the diurnal variation of PAI-1 antigen differs for the genotypes of the4G5G polymorphism. A population-based, cross-sectional study was performed among 263 subjects selected from the Rotterdam Study, a population-based cohort of 7983 men and women aged 55 years and older. The 4G allele was associated with a more pronounced circadian expression of PAI-1 antigen. Morning PAI-1 antigen concentrations were 79 ng/mL (95% confidence interval [CI], 68-92) in subjects homozygous for 4G, 62 ng/mL (95% CI, 54-72) in heterozygous subjects, and 59 ng/mL (95% CI, 49-71) in subjects homozygous for 5G. While respective PAI-1 antigen concentrations in the afternoon were 40 ng/mL (95% CI, 33-49), 41 ng/mL (95% CI, 37-47), and 40 ng/mL (95% CI, 49-71). These findings suggest that the morning increase in PAI-1 antigen concentration is more pronounced among subjects homozygous for the4G allele compared with the morning increase among the other genotypes. Additionally, these findings show that homozygosity for the 4G allele is associated with increased PAI-1 levels during the morning only.
Phase Separation in Metal Oxides
Authors: Rao C. N. R. , Vanitha P. V. , Cheetham Anthony K.
Published: February 2003

A fascinating phenomenon, recently found to occur in certain transition‐metal oxides, is phase separation wherein pure, nominally monophasic oxides of transition metals with well‐defined compositions separate into two or more phases over a specific temperature range. Such phase separation is entirely reversible, and is generally the result of a competition between charge‐localization and ‐delocalization, the two situations being associated with contrasting electronic and magnetic properties. Coexistence of more than one phase, therefore, gives rise to electronic inhomogeneity and a diverse variety of magnetic, transport, and other properties, not normally expected of the nominal monophasic composition. An interesting feature of phase separation is that it covers a wide range of length scales anywhere between 1–200 nm. While cuprates and manganates, especially the latter, provide excellent examples of phase separation, it is possible that many other transition‐metal compounds with extended structures will be found to exhibit phase separation.
The Characterisation of Supported Platinum Nanoparticles on Carbon Used for Enantioselective Hydrogenation: A Combined Electrochemical–STM Approach
Authors: Attard Gary A. , Ahmadi Ahmad , Jenkins David J. , Hazzazi Omar A. , Wells Peter B. , Griffin Ken G. , Johnston Peter , Gillies Jennifer E.
Published: February 2003

The action of chiral modifiers like cinchonine and cinchonidine in facilitating enationselectivity in heterogeneous catalysis is investigated using a combination of electrochemical and scanning probe methods. The surface chirality of corner kink sites is suggested as being crucial for chirality recognition at supported catalyst nanoparticles. Other aspects of chirality in relation to one, two, three and four dimensions are also discussed.
Preparation, structure and thermal properties of CuGa5Se8
Authors: Orlova N. S. , Bodnar I. V. , Kushner T. L.
Published: February 2003

The structural parameters, the axial thermal expansion coefficients and the characteristic Debye temperatures for the order vacancy compound CuGa5Se8 with the chalcopyrite‐related structure, prepared by the Bridgman technique, were determined at different temperatures between 90 and 650 K by the X‐ray diffraction method. The melting point of this compound was defined from the differential thermal analysis data. The anisotropy of thermal expansion in CuGa5Se8 is shown to exist with the coefficients along a‐axis being larger than those along the c‐axis throughout the temperature range studied.
Diradical versus Concerted Mechanisms for the Dihydroxylation of Protoanemonin by OsO4 and OsO4−NH3 − The Effect of the Base in the Reaction
Authors: Ujaque Gregori , Maseras Feliu , Lledós Agustí
Published: February 2003

The dihydroxylation of a set of monosubstituted olefins [ethene (1), propene (2), styrene (3)] and 5‐methylene‐2(5H)‐furanone [protoanemonin (4)] by osmium tetroxide have been studied by means of DFT (B3LYP) calculations. The effect on the reaction mechanism of the coordination of a base (NH3) to OsO4 (5) to form OsO4−NH3 (6) has been investigated. These calculations show that the activation barriers for the [3+2] concerted mechanisms are lowered by the presence of an amine coordinating the osmium tetroxide, in agreement with experiment. For the dihydroxylation of protoanemonin (an olefin having a stepwise diradical mechanism in the Diels−Alder reaction) both the concerted and the diradical mechanisms have been evaluated. These studies indicate that the dihydroxylation of olefins proceeds through a concerted mechanism, although in the dihydroxylation of protoanemonin the diradical mechanism may play a significant role. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Knowledge sharing in cooperative research and development
Authors: Sakakibara Mariko
Published: February 2003

This article examines the effects of knowledge sharing or endogenous spillovers among R&D consortia participants on R&D competition when R&D enhances a firm's absorptive capacity. A three‐stage model illustrates how different compositions of R&D consortia affect endogenous spillover rates and R&D spending of participants. When consortium participants possess complementary knowledge, the model suggests that participation increases the degree of knowledge sharing and intensifies firms' R&D efforts to learn from other members compared with the case when no cooperation takes place. This type of R&D consortia is welfare enhancing, justifying government support for these projects. Copyright © 2003 John Wiley & Sons, Ltd.
Isotopic alteration of mammalian tooth enamel
Authors: Schoeninger M. J. , Hallin K. , Reeser H. , Valley John W. , Fournelle John
Published: February 2003

Mammalian tooth enamel carbonates from a Pliocene site at Allia Bay in northern Kenya show variable carbon and oxygen isotopic alteration. Sample screening by cathodoluminescence, prior to isotopic analysis, identified areas of extensive chemical alteration and others that were minimally altered. The luminescent patterns were used to guide sampling for the isotope study. Carbon stable isotope ratios of the apatite carbonate from luminescent enamel exteriors differ from the ratios in the enamel interiors and the magnitude of difference varies widely. The interior of the enamel usually retains the carbon isotope ratios expected based on faunal identification, but in a minority of cases, all of the enamel appears to be altered isotopically. Among fauna with an apparent mixed feeding signal, it is particularly difficult to determine whether the δ13C value is due to an actual mixed feeding strategy during life or to alteration toward sediment values. Palaeoecological reconstructions based on the δ13C values of enamel carbonate in browsing fauna would be affected, in many cases, since differences of 1‰ are significant for such reconstructions. Even so, careful selection of unaltered enamel sections should avoid this problem. Palaeodiet reconstruction would be less affected except in those cases where the alteration approaches 5‰. In such cases, a mixed feeding strategy would be the erroneous interpretation of the data. Oxygen isotope ratios in the enamel carbonates show no pattern and the retention of biogenic values is unlikely. For this reason, palaeotemperature reconstructions, based on the δ18O values of the enamel carbonate, would not be possible at this site. Copyright © 2003 John Wiley & Sons, Ltd.
What do stable isotopes tell us about hominid dietary and ecological niches in the pliocene?
Authors: Lee‐Thorp J. A. , Sponheimer M. , van der Merwe N. J.
Published: February 2003

By now a reasonable set of carbon and oxygen isotope data from tooth enamel has been accumulated for South African Plio‐Pleistocene hominids and associated fauna. Almost all individuals measured, independent of species and importantly, environment, show significant C4 dietary inputs with some individuals showing very substantial C4 inputs. This implies interactions with grassy environments for a period of well over a million years, a period that saw environments in southern Africa shift from closed woodlands to more open, grassy landscapes. Carbon isotope analysis alone is unable to permit the important distinction between direct consumption of grasses, or indirect consumption via grass‐eating animals, such as small vertebrates and invertebrates. Other chemical tools provide ambiguous results. For instance, hominid strontium/calcium distributions at Swartkrans have been interpreted as supporting omnivory, but other explanations are equally plausible. Relatively low oxygen isotope values for all hominids in comparison to associated fauna show similarities with suids, monkeys and carnivores, but the causes of these similarities are as yet poorly understood. On present evidence hominid interaction with grassland foods is secure although their exact nature remains elusive. Copyright © 2003 John Wiley & Sons, Ltd.
On bone collagen—apatite‐carbonate isotopic relationships
Authors: Hedges R. E. M.
Published: February 2003

This paper addresses possible underlying causes of the observed systematic spacings in the carbon isotopic composition of bone collagen and bone apatite‐carbonate when herbivores, omnivores and carnivores are compared. In particular it examines whether the observed systematic spacings are due to dietary differences, or to metabolic differences. It concludes that a simple model for diet‐to‐collagen isotopic fractionation (based on dietary difference) can account for half of the observed spacing, but probably not more than that. It also examines the role of methanogenesis and argues that this is a feasible explanation for ruminant and, to a lesser extent, hindgut fermenter, spacing values, although again it is difficult to account for the full amount observed. It also considers the implications of observations indicating that much of the change due to different diets in a given species is probably due to isotopic shifts in bone carbonate, rather than collagen. Copyright © 2003 John Wiley & Sons, Ltd.
Surface modification of a liquid‐crystalline polymer for copper metallization
Authors: Ge J. , Turunen M. P. K. , Kivilahti J. K.
Published: February 2003

The effects of different surface modifications on the adhesion of copper to a liquid‐crystalline polymer (LCP) were investigated with X‐ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, contact‐angle measurements, and pull tests. High pull‐strength values were achieved when copper was sputter‐deposited onto plasma and reactive‐ion‐etching (RIE)‐pretreated LCP surfaces. The values were comparable to the reference pull strengths obtained with laminated copper on the LCP. The adhesion was relatively insensitive to the employed feed gas in the pretreatments. The surface characterizations revealed that for RIE and plasma treatments, the enhanced adhesion was attributable to the synergistic effects of the increased surface roughness and polar component of the surface free energy of the polymer. However, if the electroless copper deposition was performed on RIE‐ or plasma‐treated surfaces, very poor adhesion was measured. Good adhesion between the LCP substrate and electrolessly deposited copper was achieved only in the case of wet‐chemical surface roughening as a result of the creation of a sufficient number of mechanical interlocking sites, together with a significant loss of oxygen functionalities, on the surface. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 623–636, 2003
An examination of the relationships between JIT and financial performance
Authors: Fullerton Rosemary R. , McWatters Cheryl S. , Fawson Chris
Published: February 2003

Despite abundant information explaining the expected benefits from successful just‐in‐time (JIT) implementation, only tenuous validation of the linkage between financial performance and JIT exists. Managers act rationally in implementing JIT if they are convinced that JIT enhances firm performance. From both a cross‐sectional and longitudinal perspective, this survey study of 253 US manufacturing firms finds significant statistical relationships between measures of profitability and the degree of specific JIT practices used. The evidence provides empirical support to the premise that firms that implement and maintain JIT manufacturing systems will reap sustainable rewards as measured by improved financial performance.
Bone formation following transplantation of genetically modified primary bone marrow stromal cells
Authors: Sugiyama Osamu , Orimo Hideo , Suzuki Satoru , Yamashita Kazuo , Ito Hiromoto , Shimada Takashi
Published: February 2003

Bone marrow stromal cells contain mesenchymal stem cells that can differentiate into a variety of mesenchymal tissues; in the presence of BMP‐2, for example, they differentiate into osteoblasts. We constructed replication‐deficient adenoviral vectors encoding human BMP‐2 (BMP‐2/Ad) or BMP‐4 (BMP‐4/Ad) and used them to transduce primary bone marrow stromal cells from the femurs of four‐week‐old female C3H mice, which then expressed and processed functional BMP‐2 or BMP‐4 protein. Enzyme assays and histochemical staining showed both groups of cells to possess alkaline phosphatase activity, a marker of differentiation into osteoblasts, though the activity was higher in cells transduced with BMP‐2/Ad. When BMP‐2/Ad‐transduced cells were injected into the thigh muscles of immunocompetent C3H mice, ossicle development was detected on radiographs within four weeks after injection. Moreover, histological analysis indicated that newly developed ossicles contain mature osseous components, including cortical bone and bone marrow, within eight weeks. Thus, syngeneic transplantation of genetically modified primary bone marrow stromal cells induced bone formation in immunocompetent mice, perhaps indicating its potential for use in the development of therapeutic protocols aimed at enhancing bone formation. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.