bluuebunny/crossref_metadata_2025 huggingface dataset:
Epstein–Barr virus‐associated carcinomas: facts and fiction
Authors: Herrmann Kathrin , Niedobitek Gerald
Published: January 2005

The Epstein–Barr virus (EBV) is associated with several human tumours including lymphoid and epithelial malignancies. Most EBV‐associated tumours are rare or occur at higher incidence only in certain geographical regions. The recently reported detection of EBV in gastric, breast, and hepatocellular carcinomas raises the possibility of involvement of the virus in the pathogenesis of common cancers. This article reviews the evidence linking EBV infection to epithelial tumours. It is concluded that at present, there is no convincing evidence to suggest that breast carcinoma and hepatocellular carcinoma are EBV‐associated tumours. Copyright © 2003 John Wiley & Sons, Ltd.
Experimental analysis of proximity as a social stimulus: Increasing on‐task behavior of an adolescent with autism
Authors: Wilczynski Susan M. , Fusilier Iantha , Dubard Melanie , Elliott Amy
Published: January 2005

Experimental analysis of social stimuli has typically been restricted to the presence or absence of verbal attention. In the present study, an ABAB design was used to assess the influence of proximity as a social stimulus. Close and distant proximity of a familiar adult was systematically manipulated to evaluate the effect of proximity on the on‐task behavior of a 15‐year‐old male with autism. Baseline, experimental analysis, and intervention phases were conducted within a self‐contained classroom. Pronounced effects of distant educator proximity to the participant were evident during both the experimental analysis and intervention, with increased on‐task behavior occurring in the distant condition. Future recommendations for the investigation of proximity as a relevant social stimulus are forwarded. © 2005 Wiley Periodicals, Inc. Psychol Schs 42: 189–196, 2005.
Complexation of flutamide by native and modified cyclodextrins
Authors: Taraszewska Joanna , Migut Katarzyna , Koźbiał Małgorzata
Published: January 2005

Complexation of flutamide (FM), the drug used in treatment of prostate cancer, with α‐, β‐ and γ‐ cyclodextrins (CDs), heptakis(2,6‐di‐O‐methyl)‐β‐CD (DM‐β‐CD), heptakis(2,3,6‐tri‐O‐methyl)‐β‐CD (TM‐β‐CD), 2‐hydroxypropyl‐β‐CD (2HP‐β‐CD) and carboxymethyl‐β‐CD (CM‐β‐CD) was studied. For all CDs the stability constants were determined by the solubility method. UV spectrophotometry and polarography were used in particular cases. The values of the stability constants increased in the order: α‐CD ≈ γ‐CD <β‐CD ≈ CM‐β‐CD <TM‐β‐CD ≈ 2HP‐β‐CD <DM‐β‐CD. For complexes of FM with β‐CD and TM‐β‐CD, the thermodynamic parameters of complexation were determined from the temperature dependence of the corresponding stability constants. For α‐, β‐, γ‐ and TM‐β‐CD, calculations using HyperChem6 software by the MM+ force field were carried out to gain some insight into the host–guest geometry. Copyright © 2003 John Wiley & Sons, Ltd.
Covalent stabilization of nanostructures: Robust block copolymer templates from novel thermoreactive systems
Authors: Drockenmuller Eric , Li Lucy Y. T. , Ryu Du Yeol , Harth Eva , Russell Thomas P. , Kim Ho‐Cheol , Hawker Craig J.
Published: January 2005

Structurally robust block copolymer templates with feature sizes of approximately 10 nm were prepared from functionalized poly(methyl methacrylate)‐b‐polystyrene block copolymers. By the inclusion of benzocyclobutene crosslinking groups in the polystyrene block, the covalent stabilization of thin films to both thermal treatment and solvent exposure became possible. In addition, the crosslinking of the poly(styrene‐benzocyclobutene) domains at 220 °C, followed by the removal of poly(methyl methacrylate), provided a robust, crosslinked nanostructure with greater processing and fabrication potential. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1028–1037, 2005
Sizing of throttling device for gas/liquid two‐phase flow part 2: Control valves, orifices, and nozzles
Authors: Diener Ralf , Schmidt Jürgen
Published: January 2005

The calculation of the mass flow rate through throttling devices is difficult when handling two‐phase flow, especially when boiling liquids flow into these fittings. Control valves and orifices are typically oversized in industry and the control range of those valves often does not fit the control requirements. In this paper the HNE‐DS method is proposed for the sizing of control valves, orifices, and nozzles in two‐phase flow. It extends the ω‐method, originally developed by Leung, by adding a boiling delay coefficient to include the degree of thermodynamic nonequilibrium at the start of the nucleation of small vapor mass fractions upstream of the fitting. The additional introduction of a slip correction factor, to take account of hydrodynamic nonequilibrium (slip), also makes it possible to calculate reliably the flow rate through control valves and orifices in both flashing and nonflashing flow.

In Part 2 the HNE‐DS method for short nozzles, orifices, and control valves is considered. Part 1 describes the sizing of safety valves using the same method. Additionally, the derivation of the HNE‐DS model is given there in detail. The predictive accuracy of the HNE‐DS model has been checked with reference to more than 1300 sets of experimental data. © 2005 American Institute of Chemical Engineers Process Saf Prog, 2005
Dissipation of acetochlor and its distribution in surface and sub‐surface soil fractions during laboratory incubations
Authors: Taylor Jason P , Mills Margaret S , Burns Richard G
Published: January 2005

Pesticides in soil are subject to a number of processes that result in transformation and biodegradation, sorption to and desorption from soil components, and diffusion and leaching. Pesticides leaching through a soil profile will be exposed to changing environmental conditions as different horizons with distinct physical, chemical and biological properties are encountered. The many ways in which soil properties influence pesticide retention and degradation need to be addressed to allow accurate predictions of environmental fate and the potential for groundwater pollution. Degradation and sorption processes were investigated in a long‐term (100 days) study of the chloroacetanilide herbicide, acetochlor. Soil cores were collected from a clay soil profile and samples taken from 0–30 cm (surface), 1.0–1.3 m (mid) and 2.7–3.0 m (deep) and treated with acetochlor (2.5, 1.25, 0.67 µg acetochlor g−1 dry wt soil, respectively). In sterile and non‐sterile conditions, acetochlor concentration in the aqueous phase declined rapidly from the surface and subsoil layers, predominantly through nonextractable residue (NER) formation on soil surfaces, but also through biodegradation and biotic transformation. Abiotic transformation was also evident in the sterile soils. Several metabolites were produced, including acetochlor‐ethane sulphonic acid and acetochlor‐oxanilic acid. Transformation was principally microbial in origin, as shown by the differences between non‐sterile and sterile soils. NER formation increased rapidly over the first 21 days in all soils and was mainly associated with the macroaggregate (>2000 µm diameter) size fractions. It is likely that acetochlor is incorporated into the macroaggregates through oxidative coupling, as humification of particulate organic matter progresses. The dissipation (ie total loss of acetochlor) half‐life values were 9.3 (surface), 12.3 (mid) and 12.6 days (deep) in the non‐sterile soils, compared with 20.9 [surface], 23.5 [mid], and 24 days [deep] in the sterile soils, demonstrating the importance of microbially driven processes in the rapid dissipation of acetochlor in soil. Copyright © 2005 Society of Chemical Industry
High‐energy vibrational modes in nitrogen‐doped ZnO
Authors: Haboeck U. , Hoffmann A. , Thomsen C. , Zeuner A. , Meyer B. K.
Published: January 2005

We present results of Raman‐scattering experiments on a series of nitrogen‐doped ZnO epilayers grown by chemical vapor deposition. Nitrogen, a potential acceptor in ZnO, was introduced by the thermal decomposition of ammonia (NH3). We found a structure consisting of at least four lines with frequencies of 2253, 2277, 2291, and 2304 cm–1. They increase in intensity simultaneously with additional modes in the energy range of the host phonons: both scale with the nitrogen concentration in the samples. The origin of the high‐energy structure is tentatively assigned to vibrations of lattice‐bound nitrogen or complexes, composed of the constituents of the dopant NH3. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Patterns of inter‐elemental effects in EDXRF and a new correction method
Authors: Ivanenko V. V. , Kustov V. N. , Metelev A. Yu.
Published: January 2005

A new method is suggested for improving the accuracy of energy‐dispersive x‐ray fluorescence analysis (EDXRF) and its implementation is described. This method is a result of studying changes in coefficients of the inter‐elemental effect, A = f(Z). We created a data bank for elements from K to Br, which accounts for the effect of three lighter and five heavier neighboring elements upon the sought element. This study offers a physical explanation of sharp bends in coefficient curves. We suggest principles for optimizing the analytical region parameters so as to reduce the effect of neighboring elements. Finally, we describe the principles of building a data bank A = f(Z, R) to account for the effect of energy resolution (R) change. Application of the suggested method to the exploration of oceanic nodules reduced the cobalt detection threshold by 50–75% (Clim−0.95 = 0.032%) and decreased the standard deviation of spectrum analysis, thus enhancing confidence in EDXRF as an effective tool for research on complex objects. The approach suggested in this study can be used with newer energy‐dispersive analyzers, including TXRF models. Copyright © 2003 John Wiley & Sons, Ltd.
Kβ/Kα x‐ray intensity ratios for bromine and iodine compounds
Authors: Küçükönder A. , Söğüt Ö. , Büyükkasap E. , Küçükönder E. , Çam H
Published: January 2005

Kβ/Kα x‐ray intensity ratios of some Br and I compounds were studied. The samples were excited by 59.5 keV γ‐rays emitted from an Am‐241 radioisotope source and characteristic K x‐rays emitted from the samples were counted by means of an Si(Li) detector which has a resolution 155 eV at 5.9 keV. The experimental values were compared with the calculated theoretical values for elemental Br and I. Copyright © 2003 John Wiley & Sons, Ltd.
Effects of baroclinicity on the cloud pattern and structure of polar lows: A high‐resolution numerical experiment
Authors: Yanase W. , Niino H.
Published: January 2005

High‐resolution numerical experiments using a three‐dimensional non‐hydrostatic model with horizontal grid size of 5 or 2 km are performed to clarify what determines the structure and cloud pattern of polar lows. An axisymmetric initial vortex is imposed in a baroclinic basic state for which thermal wind balance holds. It is found that when the baroclinicity is absent, a hurricane‐like vortex with spiral cloud bands, a cloud‐free eye, and a warm core develops. When the baroclinicity is strong, on the other hand, a vortex with a comma‐shaped cloud and slightly larger horizontal scale develops. The former appears to develop due to CISK/WISHE mechanism, while the latter due to baroclinic instability modified by latent heating.
Nitrogen loss from watersheds of interior Alaska underlain with discontinuous permafrost
Authors: Jones Jeremy B. , Petrone Kevin C. , Finlay Jacques C. , Hinzman Larry D. , Bolton W. Robert
Published: January 2005

We constructed annual nitrogen budgets for four years for three watersheds underlain with discontinuous permafrost in interior Alaska. During all years, nitrogen export in stream flow exceeded input from deposition, with loss rate greatest from the two watersheds with the lowest spatial extents of permafrost. Elevated nitrogen export appears to be common in regions with discontinuous permafrost, based on nitrogen concentration in streams spanning a latitudinal gradient in permafrost coverage. This pattern of nitrogen loss is counter to temperate regions, where watersheds retain nitrogen even with elevated atmospheric deposition, and unexpected, given that terrestrial primary production appears to be nitrogen limited.
Electron‐acoustic solitary waves and double layers with an electron beam and phase space electron vortices in space plasmas
Authors: El‐Taibany W. F.
Published: January 2005

The nonlinear propagation of electron acoustic waves (EAWs) in a plasma composed of a cold electron fluid, hot electrons obeying trapped/vortex‐like distribution, warm electron beam, and stationary ions is considered. The streaming velocity of the beam, uo, plays the dominant role in changing the topology of the linear dispersion relation. For small but finite amplitude EAWs, a modified Korteweg de Vries (MKdV) equation is derived. It is found that the MKdV supports EAWs having a positive potential, which corresponds to a hole (hump) in the cold (hot) electron number density. The energy soliton amplitude decreases, though its width increases for any increase in the beam parameters. In the vicinity of the isothermal population, a nonlinear evolution equation with mixed nonlinearity is obtained. Its solution gives a (compressive/rarefactive) soliton or a compressive double layer (DL) depending on the system parameters. For arbitrary amplitude EAWs, the exact Sagdeev potential has been derived. The admitted Mach number regime widens due to an increase of the beam parameters. With a better approximation in the Sagdeev potential, more features of solitary waves, e.g., spiky and explosive, are also highlighted. The introduced effects modify significantly the wave velocity, the amplitude, and the width of the EAWs investigated numerically. This theoretical model is in good agreement with the broadband noise emission observed by Geotail spacecraft in the plasma sheet boundary layer of the Earth's magnetosphere.
C and C+ in the Venusian thermosphere/ionosphere
Authors: Fox J. L. , Paxton L. J.
Published: January 2005

We have constructed standard low and high solar activity models of the Venus thermosphere, which take into account revised rate coefficients for production and loss processes for C and C+, high‐resolution cross sections for photodissociation of CO, and recent solar fluxes from the Solar 2000 v1.24 and v2.22 models of Tobiska [2004]. Among the most important changes is the inclusion of the branching ratio for the channel of dissociative recombination of CO2+ that produces C + O2, which has been measured recently by Seiersen et al. [2003]. We find that unlike Mars, where the production of C is dominated by dissociative recombination of CO2+, photodissociation of CO is the most important source of C in the Venus thermosphere, as previous models have shown. The loss of C is dominated by reaction with O2 for molecular oxygen mixing ratios greater than 1 × 10−4. We also construct here a model that is appropriate to the first year of the Pioneer Venus mission, when the solar activity was moderately high. We vary the O2 mixing ratio at 90 km from 1 × 10−4 to 1 × 10−2, and we predict the resulting C density profiles. By comparing these profiles to that derived from the Pioneer Venus Orbiter Ultraviolet Spectrometer limb profiles of the 1561 and 1657 Å resonance lines, we derive a “best fit” value of the O2 abundance, which is determined to be slightly larger than 3 × 10−4. We construct model density profiles of C+ for four values of the the rate coefficient for the charge transfer reaction O+ + C → C+ + O from 1 × 10−11 to 3 × 10−10 cm3 s−1. We then compare the moderately high solar activity model C+ profiles for a solar zenith angle of 25° to that obtained by the Pioneer Venus Orbiter Ion Mass Spectrometer for orbit 200, for which the value of F10.7 ∼ 200. We find that the “best fit” rate coefficient for the charge transfer reaction is in the range (0.9–1.3) × 10−10 cm3 s−1.
Characteristic magnetic field and speed properties of interplanetary coronal mass ejections and their sheath regions
Authors: Owens M. J. , Cargill P. J. , Pagel C. , Siscoe G. L. , Crooker N. U.
Published: January 2005

Prediction of the solar wind conditions in near‐Earth space, arising from both quasi‐steady and transient structures, is essential for space weather forecasting. To achieve forecast lead times of a day or more, such predictions must be made on the basis of remote solar observations. A number of empirical prediction schemes have been proposed to forecast the transit time and speed of coronal mass ejections (CMEs) at 1 AU. However, the current lack of magnetic field measurements in the corona severely limits our ability to forecast the 1 AU magnetic field strengths resulting from interplanetary CMEs (ICMEs). In this study we investigate the relation between the characteristic magnetic field strengths and speeds of both magnetic cloud and noncloud ICMEs at 1 AU. Correlation between field and speed is found to be significant only in the sheath region ahead of magnetic clouds, not within the clouds themselves. The lack of such a relation in the sheaths ahead of noncloud ICMEs is consistent with such ICMEs being skimming encounters of magnetic clouds, though other explanations are also put forward. Linear fits to the radial speed profiles of ejecta reveal that faster‐traveling ICMEs are also expanding more at 1 AU. We combine these empirical relations to form a prediction scheme for the magnetic field strength in the sheaths ahead of magnetic clouds and also suggest a method for predicting the radial speed profile through an ICME on the basis of upstream measurements.
One‐dimensional physical reference models for the upper mantle and transition zone: Combining seismic and mineral physics constraints
Authors: Cammarano F. , Deuss A. , Goes S. , Giardini D.
Published: January 2005

One‐dimensional seismic reference models are known to be a nonunique solution to global seismic data, hampering an interpretation in terms of physical structure. Here we test the compatibility of the simplest hypothesis of a mantle convecting as a whole, with a constant pyrolitic composition with phase transitions, directly against the kind of seismic data that went into global seismic reference models, focusing on upper mantle structure down to 800 km depth. By randomly varying the elastic and anelastic parameters of the main mantle minerals within their uncertainty bounds, we generate a set of 100,000 adiabatic, pyrolitic models. A small number of these models (<0.1%) give a fit to far‐regional P and S travel times (reprocessed ISC catalog, Δ = 18.5°–26°) and fundamental spheroidal and toroidal modes (reference Earth model Web page, l > 60) that is as satisfactory as the fit of preliminary reference Earth model (PREM) or AK135(‐F). Although the accepted models have widely different combinations of the mineral parameters, there is a preference for a relatively high olivine shear modulus and its pressure and temperature derivatives, relatively low wadsleyite bulk and shear parameters, and relatively high ringwoodite bulk modulus derivatives. The resulting seismic profiles are very similar and, compared to PREM or AK135, have lower velocities above 400 km, larger jumps near “410,” lower transition zone gradients, lower jumps around “660,” and stronger gradients directly below. Such physical models that fit seismic data well enough to be useful as a seismic reference model can significantly facilitate physical interpretation of seismic structures.
Vapor‐phase transport in the near‐drift environment at Yucca Mountain
Authors: Salve Rohit , Kneafsey Timothy J.
Published: January 2005

A key issue regarding the performance of the potential high‐level radioactive waste repository at Yucca Mountain, Nevada, is the likelihood of precipitation percolating a vertical distance of ∼300 m through fractured unsaturated rock into drifts containing waste packages. Water enhances waste package corrosion and is required for transport of released radionuclides. To evaluate the propensity for seepage into tunnels at Yucca Mountain, a 5‐m‐diameter, 2.7‐km‐long tunnel, commonly referred to as the Cross Drift (CD), was excavated in 1998, branching off from the main Exploratory Studies Facility tunnel. Sections of this tunnel have been isolated from ventilation for extended periods over the last 4 years. We present continuous measurements of relative humidity and temperature and periodic observations of liquid water in the CD over two periods. During this observation duration the terminal section of the drift was partitioned into four sections by bulkheads, and ventilation to these sections was minimized to a few days. We compare these observations to results from analytical and numerical models to investigate processes associated with the movement of water vapor between the tunnel bore and the surrounding fractured rock formation. Observations from this effort indicate that fractures can be primary paths for unsaturated zone vapor flow in the immediate vicinity of emplacement drifts. Observations, measurements, and analysis indicate the need for a model that includes fracture‐dominated vapor transport as a significant contributor to total water flow into the drifts.
Constraining a physically based Soil‐Vegetation‐Atmosphere Transfer model with surface water content and thermal infrared brightness temperature measurements using a multiobjective approach
Authors: Demarty Jérôme , Ottlé Catherine , Braud Isabelle , Olioso Albert , Frangi Jean Pierre , Gupta Hoshin V. , Bastidas Luis A.
Published: January 2005

This article reports on a multiobjective approach which is carried out on the physically based Soil‐Vegetation‐Atmosphere Transfer (SVAT) model. This approach is designed for (1) analyzing the model sensitivity to its input parameters under various environmental conditions and (2) assessing input parameters through the combined assimilation of the surface water content and the thermal infrared brightness temperature. To reach these goals, a multiobjective calibration iterative procedure (MCIP) is applied on the Simple Soil Plant Atmosphere Transfer–Remote Sensing (SiSPAT‐RS) model. This new multiobjective approach consists of performing successive contractions of the feasible parameter space with the multiobjective generalized sensitivity analysis algorithm. Results show that the MCIP is an original and pertinent approach both for improving model calibration (i.e., reducing the a posteriori preferential ranges) and for driving a detailed SVAT model using various calibration data. The usefulness of the water content of the upper 5 cm and the thermal infrared brightness temperature for retrieving quantitative information about the main input surface parameters is also underlined. This study opens perspectives in the combined assimilation of various multispectral remotely sensed observations, such as passive microwaves and thermal infrared signals.
Association of 14-3-3γ and Phosphorylated Bad Attenuates Injury in Ischemic Astrocytes
Authors: Chen Xiao Qian , Fung Yin-Wan Wendy , Yu Albert Cheung Hoi
Published: January 2005

Our recent findings indicate an induced upregulation of 14-3-3γ mRNA and protein in ischemic cortical astrocytes. Despite being brain-specific, the functional role of 14-3-3γ in the brain still remains largely unknown. In this study, we show that among all the 14-3-3 isoforms, only the γ isoform is inducible under ischemia in astrocytes. Furthermore, this upregulation of 14-3-3γ may play a specific protective role in astrocytes under ischemia. Overexpression experiments and antisense treatment show that an elevation of 14-3-3γ protein in astrocytes promotes survival, while a decrease in 14-3-3γ enhances apoptosis in astrocytes under ischemia. Under ischemia, endogenous 14-3-3γ binds p-Bad, thus preventing Bad from entering mitochondria to initiate apoptosis. Therefore, 14-3-3γ is selectively induced during ischemia to protect astrocytes from apoptosis through p-Bad-related signaling.
G-CSF Reduces Infarct Volume and Improves Functional Outcome after Transient Focal Cerebral Ischemia in Mice
Authors: Gibson Claire L , Bath Philip MW , Murphy Sean P
Published: January 2005

Growth factors possess neuroprotective and neurotrophic properties in vitro, but few have been extensively studied in vivo after stroke. In the present study, we investigated the potential functional benefits of granulocyte colony-stimulating factor (G-CSF) administration after focal cerebral ischemia. Male mice underwent 60-minute middle cerebral artery occlusion (MCAO) and received G-CSF (50 μg/kg, subcutaneously) or vehicle (saline) at the onset of reperfusion. Granulocyte colony-stimulating factor-treated mice killed at 48 hours after MCAO revealed a >45% reduction ( P<0.05) in lesion volume. In terms of body weight recovery, and in tests of motor (grid test and rotarod) and cognitive ability (water maze), MCAO significantly worsened the outcome in vehicle-treated mice as compared with shams ( P<0.05). However, G-CSF treatment was beneficial as, compared with vehicle, this significantly improved weight recovery and motor ability. This effect was most apparent on the water maze where G-CSF-treated mice were indistinguishable from shams in terms of acquiring the task. These results indicate long-term beneficial effects of a single dose of G-CSF administered on reperfusion, and illustrate the need to further investigate the mechanisms of G-CSF action.
Optical properties of Er3+ and Tm3+ ions in a tellurite glass
Authors: Yamauchi Hiroki , Senthil Murugan Ganapathy , Ohishi Yasutake
Published: January 2005

Optical spectroscopic properties of Er3+ and Tm3+ ions in a tellurite glass, TeO2-BaO-SrO-Nb2O5 (TBSN), were investigated for C- and S-band optical amplifications. On the basis of consideration for cross relaxation among Tm3+ ions and multiphonon relaxation, it was shown that the presence of Nb2O5, which was a source of the highest energy phonon, contributed to the relaxation processes in TBSN glasses.
Electronic properties of a pure and sodium-doped C70 single layer adsorbed on Al polycrystalline surface
Authors: Pardini T. , Cepek C. , Larciprete R. , Sangaletti L. , Pagliara S. , Gotter R. , Floreano L. , Verdini A. , Morgante A. , Parmigiani F. , Goldoni A.
Published: January 2005

Core level and valence band photoemission measurements combined with near edge x-ray absorption fine structure measurements were performed on a single C70 layer adsorbed on polycrystalline Al (1 ML-C70/Al) (ML—monolayer), pure and doped with sodium atoms. The data obtained from the pure ML chemisorbed on Al surface show a semiconducting behavior of the system, which is characterized by a covalent bond between the adsorbate and the substrate. The same data show also that the C70 molecules tend to orient themselves with the C5v axis perpendicular to the surface in analogy to what observed for 1 ML-C70/Cu(111). By doping the sample with sodium atoms a charge transfer from the alkali atoms to the lowest unoccupied molecular orbital (LUMO) of the C70 molecules takes place, as underlined by the gradual increasing intensity of the C70 LUMO peak as a function of doping. Nevertheless, no metallic phases are observed for any doping step.
Finite-element modeling method for the prediction of the complex effective permittivity of two-phase random statistically isotropic heterostructures
Authors: Myroshnychenko Viktor , Brosseau Christian
Published: January 2005

This article is devoted to the study of the complex permittivity of two-dimensional two-phase statistically isotropic heterostructures on a small scale such that the quasistatic limit is applicable. Even though several analytical approximation techniques have been developed in the past, today it is desirable to be able to simulate these media via computer, which necessitates the development of efficient numerical techniques for the solution of the resulting equations. The simulation data concern the effective permittivity of continuum composites consisting of distributions of hard disks of a dielectric phase randomly dispersed in a continuous matrix of another dielectric phase. The three-dimensional equivalent of this model would be a composite with cylindrical symmetry, i.e., all interfaces are parallel to a fixed direction. The two constituents are assumed to be isotropic and homogeneous materials with scalar permittivities. Ab initio calculations are accomplished self-consistently with a computer code. The distribution of monodisperse inclusions is equilibrated by the Monte Carlo method and the dielectric study was carried out using the finite element method. Results are first presented documenting the effects of the surface fraction of the disks and the permittivity contrast between the two phases on the complex effective permittivity of the composite material. The numerical results are then compared with available effective medium approaches and bounds methods. The effective complex permittivity is found to lie within the four-point bounds in the complex plane and between the curves corresponding to Maxwell Garnett and asymmetric Bruggeman formulas. The scaling analysis reported here highlights a number of complexities not previously noted for this system. The exponents governing the critical behavior of the real and imaginary parts of the complex permittivity can be quite different from those characterizing the continuum percolation phenomena in a statistically inhomogeneous system of partially penetrable disks.
Coupled cluster methods including triple excitations for excited states of radicals
Authors: Smith Christopher E. , King Rollin A. , Crawford T. Daniel
Published: January 2005

We report an extension of the coupled cluster iterative-triples model, CC3, to excited states of open-shell molecules, including radicals. We define the method for both spin-unrestricted Hartree–Fock (UHF) and spin-restricted open-shell Hartree–Fock (ROHF) reference determinants and discuss its efficient implementation in the PSI3 program package. The program is streamlined to use at most O(N7) computational steps and avoids storage of the triple-excitation amplitudes for both the ground- and excited-state calculations. The excitation-energy program makes use of a Löwdin projection formalism (comparable to that of earlier implementations) that allows computational reduction of the Davidson algorithm to only the single- and double-excitation space, but limits the calculation to only one excited state at a time. However, a root-following algorithm may be used to compute energies for multiple states of the same symmetry. Benchmark applications of the new methods to the lowest valence B12 state of the allyl radical, low-lying states of the CH and CO+ diatomics, and the nitromethyl radical show substantial improvement over ROHF- and UHF-based CCSD excitation energies for states with strong double-excitation character or cases suffering from significant spin contamination. For the allyl radical, CC3 adiabatic excitation energies differ from experiment by less than 0.02 eV, while for the Σ+2 state of CH, significant errors of more than 0.4 eV remain.
On line-ratio analysis for helium–argon microwave discharges
Authors: Koleva I. , Shivarova A. , Makasheva K. , Schlüter H.
Published: January 2005

Regarding spectroscopy diagnostics via line-intensity ratio of high-density diffusion-controlled discharges in helium–argon gas mixtures, the study presents a collisional-radiative model of the discharge. In order to show variations of excited-state population densities and line-intensity ratios related to changes of plasma density and electron temperature, the model is applied to surface-wave-sustained discharges, since the axial structure of these discharges displays self-consistent variations of the discharge characteristics. The comparison with the corona model shows the necessity of developing a collisional-radiative model. Possibilities for simultaneous determination—based on the collisional-radiative model—of electron temperature and plasma density from measurements of line-intensity ratios are outlined.
Performance of the vertical optical filter for the NG-3 30m SANS instrument at the National Institute of Standards and Technology's Center for Neutron Research
Authors: Cook Jeremy C. , Glinka Charles J. , Schröder Ivan G.
Published: January 2005

The straight neutron guide and crystal filter formerly used to supply a cold neutron beam to the NG-3 30m small angle scattering instrument at the National Institute of Standards and Technology Center for Neutron Research has been replaced by a vertically-kinked “optical filter” neutron guide that eliminates direct lines-of-sight between the instrument and the neutron source. Due to pre-existing lateral spatial constraints, the optical filter bend is in a vertical plane requiring a vertical displacement of the sample-detector axis by about 14cm. The optical filter is successful in excluding unwanted fast neutrons and gamma rays from the beam at the sample position without the use of crystal filters. We show that the optical filter provides neutron current density gains at the sample by a factor of about 1.8 at 15Å neutron wavelength with negligible increase in the beam divergence, whilst allowing some measurement capability at wavelengths shorter than 4Å (previously excluded by the beryllium–bismuth crystal filter).
Interaction of wide-band-gap single crystals with 248-nm excimer laser irradiation. X. Laser-induced near-surface absorption in single-crystal NaCl
Authors: Nwe K. H. , Langford S. C. , Dickinson J. T. , Hess W. P.
Published: January 2005

Ultraviolet laser-induced desorption of neutral atoms and molecules from nominally transparent, ionic materials can yield particle velocities consistent with surface temperatures of a few thousand kelvin even in the absence of visible surface damage. The origin of the laser absorption required for this surface heating has been often overlooked. In this work, we report simultaneous neutral emission and laser transmission measurements on single-crystal NaCl exposed to 248-nm excimer laser radiation. As much as 20% of the incident radiation at 248 nm must be absorbed in the near-surface region to account for the observed particle velocities. We show that the laser absorption grows from low values over several pulses and saturates at values sufficient to account for the surface temperatures required to explain the observed particle velocity distributions. The growth of absorption in these early pulses is accompanied by a corresponding increase in the emission intensities. The diffuse reflectance spectra acquired after exposure suggest that near-surface V-type centers are responsible for most of the absorption at 248 nm in single-crystal NaCl.
Investigation of periodically poled lithium niobate crystals by light diffraction
Authors: Müller M. , Soergel E. , Buse K. , Langrock C. , Fejer M. M.
Published: January 2005

Periodically poled lithium niobate crystals are investigated by illumination along the crystallographic c axis while applying an external electric field. The resulting diffraction patterns are in good agreement with the results of numerical simulations and directly yield first information such as periodicity, duty cycle, and homogeneity of the domain patterns.
Automated high-resolution frequency-stabilized cavity ring-down absorption spectrometer
Authors: Hodges Joseph T. , Ciuryło Roman
Published: January 2005

We describe a frequency-stabilized cavity ring-down absorption spectrometer with automated scanning capabilities. The system utilizes the comb of ring-down cavity resonances as frequency markers for spectral scans. The comb is actively stabilized with respect to a frequency-stabilized reference laser, and the continuous wave, single-mode probe laser frequency is in turn actively stabilized with respect to resonances of the ring-down cavity frequency comb. Ring-down spectra are obtained by locking the external-cavity diode laser probe to sequential cavity resonances (separated by the ring-down cavity free spectral range), and the ring-down cavity frequency comb is translated by controlled amounts using acousto-optic frequency shifting methods for fine frequency steps less than the free-spectral range. A computer-controlled method for automating frequency tuning and probe laser locking to the cavity resonances is described, and high-resolution near-infrared (vicinity of 10712cm−1) absorption spectra of water vapor are presented. A frequency resolution of ≈1MHz and minimum measurable line intensity of 10−27cm2cm−1molecule−1 are demonstrated.
A Scalable Stereoselective Synthesis of Scymnol
Authors: Adhikari Raju , Cundy Darren J. , Francis Craig L. , Gebara-Coghlan Mariana , Krywult Beata , Lubin Carolyn , Simpson Gregory W. , Yang Qi
Published: January 2005

A high-yielding, stereoselective synthesis of scymnol 1 has been carried out in five steps starting from commercially available cholic acid 2. The synthesis was designed with the aim of eventual large-scale processing. Triformyloxycholic acid chloride 4 was treated with the magnesium enolate of diethyl malonate to afford the β-keto diester, diethyl 3α,7α,12α-triformyloxy-24-oxo-5β-cholestane-26,27-dioate 5. The key step in the synthesis was the stereoselective hydrogenation of β-keto diester 5 to give the corresponding β-hydroxy diester 6 using a BINAP ruthenium(ii) catalyst. Subsequent reduction of the diester moiety and deprotection of the hydroxyl groups afforded scymnol 1.
L-Ribose: an Easily Prepared Rare Sugar
Authors: Angyal Stephen J.
Published: January 2005

An old method has been updated to provide an easy one-step process for the synthesis of l-ribose.
Cyclic α-Amino Acids via Enantioselective Metal-Catalyzed Cascade Reactions of Dienamides in Supercritical Carbon Dioxide
Authors: Teoh Euneace , Jackson W. Roy , Robinson Andrea J.
Published: January 2005

Highly enantioselective conversion of dienamides into cyclic α-amino acids can be achieved by a single-pot, tandem hydrogenation–hydroformylation–cyclization–elimination sequence using a single catalyst and supercritical carbon dioxide (scCO2) as the reaction solvent at total pressures significantly lower than those previously reported for related hydrogenation and hydroformylation reactions.
Spongosoritin A: A New Polyketide from a Fijian Marine Sponge, Spongosorites sp.
Authors: Capon Robert J. , Singh Sachin , Ali Sadaquat , Sotheeswaran Subramaniam
Published: January 2005

A new polyketide, spongosoritin A, with a rare vinylagous α,β-unsaturated γ-lactone moiety was isolated from a Fijian marine sponge, Spongosorites sp., and the structure assigned by detailed spectroscopic analysis.
A partial atomic structure for the flagellar hook of
Salmonella typhimurium
Authors: Shaikh Tanvir R. , Thomas Dennis R. , Chen James Z. , Samatey Fadel A. , Matsunami Hideyuki , Imada Katsumi , Namba Keiichi , DeRosier David J.
Published: January 2005

The axial proteins of the bacterial flagellum function as a drive shaft, universal joint, and propeller driven by the flagellar rotary motor; they also form the putative protein export channel. The N- and C-terminal sequences of the eight axial proteins were predicted to form interlocking α-domains generating an axial tube. We report on an ≈1-nm resolution map of the hook from
Salmonella typhimurium
, which reveals such a tube made from interdigitated, 1-nm rod-like densities similar to those seen in maps of the filament. Atomic models for the two outer domains of the hook subunit were docked into the corresponding outermost features of the map. The N and C termini of the hook subunit fragment are positioned next to each other and face toward the axis of the hook. The placement of these termini would permit the residues missing in the fragment to form the rod-like features that form the core domain of the hook. We also fit the hook atomic model to an ≈2-nm resolution map of the hook from
Caulobacter crescentus
. The hook protein sequence from
C. crescentus
is largely homologous to that of
S. typhimurium
except for a large insertion (20 kDa). According to difference maps and our fitting, this insertion is found on the outer surface of the hook, consistent with our modeling of the hook.
Breaking sieve for steric exclusion of a noncognate amino acid from active site of a tRNA synthetase
Authors: Swairjo Manal A. , Schimmel Paul R.
Published: January 2005

The genetic code is fixed in aminoacylation reactions catalyzed by aminoacyl-tRNA synthetases. Amino acid discrimination occurs at two sites: one for amino acid activation and aminoacylation and one for editing misactivated amino acids. Although the active site sieves out bulkier amino acids, misactivation occurs with substrates whose side chains are smaller than the cognate one. Paradoxically, although alanyl-tRNA synthetase activates glycine as well as alanine, the sterically larger (than alanine) serine is also misactivated. Here, we report crystal structures of an active fragment of
Aquifex aeolicus
alanyl-tRNA synthetase complexed, separately, with Mg
2+
–ATP, alanine, glycine, and serine. Ala and Gly are bound in similar orientations in a side-chain-accommodating pocket, where α-amino and carboxyl groups are stabilized by salt bridges, and the carboxyl by an H-bond from the side chain NH
2
of Asn-194. In contrast, whereas the same two salt bridges stabilize bound Ser, H-bonding of the highly conserved (among class II tRNA synthetases) Asn-194 side chain NH
2
to the Ser OH, instead of to the carboxyl, forces pocket expansion. Significantly, in the Mg
2+
–ATP complex, Asn-194 coordinates a Mg
2+
-α-phosphate bridge. Thus, the sieve for Ser exclusion is broken because of selective pressure to retain Asn-194 for Mg
2+
–ATP and Ala binding.
The content of a Gaussian polynomial is invertible
Authors: Loper K. , Roitman Moshe
Published: January 2005

Let

R
R

be an integral domain and let

f
(
X
)

f(X)

be a nonzero polynomial in

R
[
X
]

R[X]

. The content of

f
f

is the ideal

c

(
f
)

\mathfrak c(f)

generated by the coefficients of

f
f

. The polynomial

f
(
X
)

f(X)

is called Gaussian if

c

(
f
g
)
=

c

(
f
)

c

(
g
)

\mathfrak c(fg) = \mathfrak c(f)\mathfrak c(g)

for all

g
(
X
)
∈
R
[
X
]

g(X) \in R[X]

. It is well known that if

c

(
f
)

\mathfrak c(f)

is an invertible ideal, then

f
f

is Gaussian. In this note we prove the converse.
Vaccine-induced protection against Borna disease in wild-type and perforin-deficient mice
Authors: Hausmann Jürgen , Baur Karen , Engelhardt Karin R. , Fischer Timo , Rziha Hanns-Joachim , Staeheli Peter
Published: January 2005

Borna disease virus (BDV) can persistently infect the central nervous system and induce CD8+T-cell-mediated neurological disease in MRL mice. To determine whether specific immune priming would prevent disease, a prime–boost immunization protocol was established in which intramuscular injection of a recombinant parapoxvirus expressing BDV nucleoprotein (BDV-N) was followed by intraperitoneal infection with vaccinia virus expressing BDV-N. Immunized wild-type and perforin-deficient mice remained healthy after intracerebral infection with BDV and contained almost no virus in the brain at 5 weeks post-challenge. Immunization failed to induce resistance against BDV in mice lacking mature CD8+T cells. Immunization of perforin-deficient mice with a poxvirus vector expressing mutant BDV-N lacking the known CD8+T-cell epitope did not efficiently block multiplication of BDV in the brain and did not prevent neurological disease, indicating that vaccine-induced immunity to BDV in wild-type and perforin-deficient mice resulted from the action of CD8+T cells.
On phylogenetic relationships among major lineages of the Gammaherpesvirinae
Authors: McGeoch Duncan J. , Gatherer Derek , Dolan Aidan
Published: January 2005

Phylogenetic relationships within the subfamily Gammaherpesvirinae of the family Herpesviridae were investigated for three species in the genus Lymphocryptovirus (or γ1 group) and nine in the genus Rhadinovirus (or γ2 group). Alignments of amino acid sequences from up to 28 genes were used to derive trees by maximum-likelihood and Bayesian Monte Carlo Markov chain methods. Two problem areas were identified involving an unresolvable multifurcation for a clade within the γ2 group, and a high divergence for Murid herpesvirus 4 (MHV4). A robust final tree was obtained, which was valid for genes from across the virus genomes and was rooted by reference to previous analyses of the whole family Herpesviridae. This tree comprised four major lineages: the γ1 group of primate viruses; a clade of artiodactyl γ2 viruses; a clade of perissodactyl γ2 viruses; and a clade of γ2 viruses with a multifurcation at its base and containing Old World and New World primate viruses, Bovine herpesvirus 4 and MHV4. Developing previous work it was proposed, on the basis of similarities between the gammaherpesvirus tree and the tree of corresponding mammalian hosts, that the first three of these major viral lineages arose in a coevolutionary manner with host lineages, while the fourth had its origin in an ancient interspecies transfer. Transfer of dates from mammalian palaeontology then allowed estimation of dates for nodes in the gammaherpesvirus tree.
A note on the relationship between real wages and employment
Authors: Christopoulos Dimitris K.
Published: January 2005

Purpose

Tests for the existence of a long‐run relationship between real wages and employment, utilising annual data from 1961‐1996 for a panel of 12 European Union countries.

Design/methodology/approach

Applies modern time series techniques organised around panel unit root and panel cointegration tests to draw sharper conclusions from the short time series that are typically available.

Findings

Indicates that a long‐run relationship between real wages and employment cannot be established. This being so, little success is expected in bringing down unemployment, the most pressing problem in the European Union, by reducing real wages.

Originality/value

Investigates the long‐run relationship between real wages and employment by conducting more reliable tests in the context of 12 European countries, namely Belgium, Denmark, Germany, Spain, France, Ireland, Italy, The Netherlands, Portugal, the UK, Norway and Finland over the period 1961‐1996.
Thomas Edison's “except one”
Authors: Hammes David , Wills Douglas
Published: January 2005

Purpose

This paper examines the monetary thought of Arthur Kitson (1861‐1937) as expressed in his published works and in recently discovered answers he submitted in 1922 to a questionnaire from Thomas Edison, the US inventor.

Design/methodology/approach

Both original source material from the Edison Archive and published sources are used to examine the subject.

Findings

It is found that Kitson's monetary thought is more orthodox than has previously been claimed by, among others, John Maynard Keynes, and more recently in the economics literature. It is also found that Kitson was the only person to support, without qualification, Edison's plan to reform the US monetary system.

Originality/value

This paper casts a new light on Kitson's monetary thought, showing the influence of Irving Fisher on Kitson. The paper also presents Edison's questionnaire and Kitson's contributory thoughts on a fiat monetary standard that the questionnaire stimulated.