bluuebunny/crossref_metadata_2025 huggingface dataset:
Management of Zenker's diverticulum and Postlaryngectomy pseudodiverticulum with the CO2 laser
Authors: Lippert Burkard M. , Folz Benedikt J. , Rudert Heinrich H. , Werner Jochen A.
Published: April 2004

Dysphagia is a common symptom and can be caused by anterior pharyngeal (pseudodiverticulum after laryngectomy) and Posterior pharyngeal (Zenker's) diverticula. The only treatment is surgical. The experience with an endoscopic treatment, especially with the CO2 laser, is limited. Between 1984 and 1996, 81 patients with dysphagia were treated endoscopically with the CO2 laser at the Department of Otorhinolaryngology‐Head and Neck Surgery, University of Kiel. In 70 patients the swallowing disorder was caused by a hypopharyngeal diverticulum, and in 11 patients it was caused by a pseudodiverticulum after laryngectomy. In the Zenker's group, more than 90% of the patients were treated successfully. Eight of 11 patients with pseudodiverticula were without symptoms, and in the remaining 3 patients dysphagia was improved after laser therapy. The excision technique was superior to the incision procedures. The rate of Postoperative complications was generally low. The microendoscopic approach with the CO2 laser is a recommendable method for the treatment of Zenker's diverticulum and pseudodiverticulum in the Postlaryngectomy patient. The surgical technique with the CO2 laser at low Power settings is a less invasive, quick, relatively safe, and effective procedure requiring only short hospitalization.
Septic arthritis of the temporomandibular joint
Authors: Hincapie Jaime W. , Tobon Diana , Diaz‐Reyes Gustavo A.
Published: April 2004

Septic arthritis of the temporomandibular joint (TMJ) is an uncommon disease associated with local factors such as joint involvement by rheumatoid arthritis or systemic factors such as diabetes, immunosuppression, or prolonged use of systemic steroids.1,2
Osteoplastic Flap for Obliteration of the Frontal Sinus: Five years’ Experience
Authors: Correa Alex J. , Duncavage James A. , Fortune D. Scott , Reinisch Lou
Published: April 2004

The objective of this retrospective study was to evaluate the osteoplastic flap (OPF) for the obliteration of the frontal sinus in this current era of endoscopic management of frontal sinus disease. A review of consecutive OPF procedures (n = 43) performed by the senior author (J.A.D.) from 1992 to 1997 was carried out. Data were gathered regarding chief symptom, medical history, previous sinus surgery, endoscopic findings in the office and at surgery, CT scan findings, and follow‐up results (mean 19.4 months). Previous endoscopic management of frontal sinus disease had failed in 24% of patients; 97% had eventual resolution of frontal sinusitis with OPF. After OPF, 63% also had improvement or resolution of disease in other paranasal sinuses. Statistically significant, Positive correlations (P< 0.05) were noted between the resolution of frontal sinusitis and improved or resolved pain, as well as the resolution of frontal sinusitis and improved or resolved infections in other paranasal sinuses. In 1998 OPF remains the standard for treating frontal sinus disease refractory to other methods. OPF can decrease the pain associated with frontal sinus infections and has a Positive impact on inflammatory disease in other paranasal sinuses.
Multimode short-wavelength perturbation growth studies for the National Ignition Facility double-shell ignition target designs
Authors: Milovich J. L. , Amendt P. , Marinak M. , Robey H.
Published: April 2004

Detailed multimode two-dimensional simulations of short-wavelength perturbations imposed on the material interfaces of a recently proposed indirect-drive double-shell ignition target [Amendt et al., Phys. Plasmas 9, 2221 (2002)] are presented. In this work, the effect of roughness imposed only on the surfaces of the inner shell is studied. Realistic perturbations are adopted from a measured spectrum of a glass capsule (as a surrogate for the high-Z inner shell). It is found that perturbing the inner surface of the inner shell shows minimal degradation in capsule performance. On the other hand, when roughness is imposed on the outer surface of the inner shell, the growth of large Legendre mode number perturbations (l>200) leads to shell breakup. Further analysis reveals a new pathway for the Rayleigh–Taylor (RT) instability. L-shell radiation (>8 keV) from the high-Z hohlraum wall ablates the outer surface of the high-Z inner shell, promoting large outward expansion which is reversed by the converging outer shell. The classic conditions for RT instability are met: low density material pushing onto the higher density inner shell. It is shown that this effect can be controlled by tamping the outward expansion of the inner shell with a variety of materials. Simulations with separate CH and Ti tampers demonstrate that the redesigned capsule can withstand perturbations with high mode number content without exhibiting shell breakup. Furthermore, the outstanding question of determining the cutoff mode number (lc) is addressed by performing simulations with successively larger maximum l, reaching values beyond 1000, and calculating the mix width of the pusher/tamper interface for the CH-tamped case. These numerical studies suggest that the mix width approaches a constant value close to 40% of the shell width at peak compression. While not a proof that lc has been found, this result suggests that a mix-relevant mode number may be within reach of current simulation capabilities.
Reduction of the ablative Rayleigh–Taylor growth rate with Gaussian picket pulses
Authors: Collins T. J. B. , Knauer J. P. , Betti R. , Boehly T. R. , Delettrez J. A. , Goncharov V. N. , Meyerhofer D. D. , McKenty P. W. , Skupsky S. , Town R. P. J.
Published: April 2004

The effect of a Gaussian prepulse (picket pulse) before a “drive” pulse on the Rayleigh–Taylor (RT) instability growth rate was measured for single-mode, 20-, 30-, and 60-μm-wavelength mass perturbations. These data, from the OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] laser system, show that the measured RT growth of mass perturbations was reduced when a picket pulse was used. The picket pulse and subsequent relaxation period, before the drive pulse, cause the foil to expand and rarefy, resulting in higher ablation velocities during the drive pulse and greater ablative stabilization. This effect was examined both computationally and experimentally for different picket-pulse intensities.
Relaxed states for Ohmically driven tokamaks with an arbitrary aspect ratio
Authors: Zhang Cheng , Zhou Deng , Menard Jonathan E.
Published: April 2004

The relaxed state of plasma in Ohmically driven tokamaks with an arbitrary aspect ratio is explored using the principle of minimum dissipation rate subject to the helicity and the energy balance. The resulting Euler–Lagrange equations are solved analytically and numerically. The self-consistent solutions of whole Euler–Lagrange equations as well as both helicity and energy balance equations are obtained numerically for the given parameters and boundary conditions. It is found that for low and general aspect ratio tokamaks, there exist different typical minimum dissipation states, corresponding respectively to different typical current profiles observed in experiments. It is also found that there exist different types of relaxed states in the different regions of the parameter space for a selected device. Each current profile mode is achieved by adjusting controllable parameters such as plasma resistivity, boundary toroidal magnetic field or boundary electric field. The results show that there exists a key parameter E0/ηB0 in determining the final relaxed states. The typical minimum dissipation state may evolve to other forms of states abruptly by increasing E0/ηB0 to be above a critical value. Three forms of current profile are presented for the low aspect ratio National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 (2000)]. The first form peaks in the edge of the high field side similar to the typical experimental form. The second peaks in the central region on the equatorial plane. The third may have a hole or reverse in the central region. Both the second and third states could be obtained by increasing E0/ηB0 to be above the critical value.
Electron acceleration by surface plasma waves in the interaction between femtosecond laser pulses and sharp-edged overdense plasmas
Authors: Kupersztych J. , Raynaud M. , Riconda C.
Published: April 2004

The relativistic acceleration of electrons by the field of surface plasma waves created in the interaction between ultrashort high-intensity laser pulses with sharp-edged overdense plasmas has been investigated. It is shown that the initial phase of the wave experienced by the electrons play a leading part by yielding a well-defined peaked structure in the energy distribution function. This study suggests that resonant excitation of surface plasma waves could result in quasi-monokinetic energetic electron bunches. When the space charge field becomes too strong, this mechanism can evolve toward a true absorption process of the surface wave energy via an enhanced “vacuum heating” mechanism generalized to the case of surface plasma waves.
Stimulated Raman scattering of a laser in a plasma with clusters
Authors: Tiwari Pawan K. , Tripathi V. K.
Published: April 2004

The presence of sub-micron size clusters in a gas jet plasma considerably modifies the dispersion relations for electromagnetic and Langmuir waves. A high intensity laser propagating through such a plasma undergoes stimulated Raman scattering (SRS). The free electrons inside the clusters play a significant role in the nonlinear coupling. The growth rate of SRS increases with the increase in cluster density in a low-density gas jet. Damping of the laser in cluster plasma introduces an intensity threshold that increases rather rapidly with decrease in pulse duration.
Response to “Comment on ‘The superposition of rotating and stationary magnetic sources: Implications for the auroral region’ ” [Phys. Plasmas 11, 1738 (2004)]
Authors: Rothwell Paul L.
Published: April 2004

Vasyliunas [Phys. Plasmas 11, 1738 (2004)] claims that the co-rotation electric field must be derived from the generalized Ohm’s law to be physically correct. However, laboratory results show that the rotation of a magnetic source produces electric fields without a plasma being present. With a plasma present these electric fields, which can be explained by Faraday’s law and the transformation of the electromagnetic field between reference frames [Phys. Plasmas 10, 2971 (2003)], form the co-rotation electric field. Therefore, a magnetohydrodynamic approach, as argued by Vasyliunas, is not required to derive the co-rotation electric field. In this Response the relevant laboratory experiments will be described in more detail, as well as their application to the Earth’s co-rotation electric field. Also, it is suggested that plasma neutrality and the inertia of the co-rotating plasma maintain E∥≠0. In response to a second round of communications, the applicability of a paper by Schiff [Proc. Natl. Acad. Sci. 25, 391 (1939)] is discussed.
Studies on a third-harmonic large-orbit gyro-traveling-wave-tube amplifier
Authors: Yang Wenyuan , Ding Wu
Published: April 2004

A third-harmonic gyro-traveling-wave-tube amplifier with a smooth cylindrical waveguide using an axis-encircling electron beam is studied. By the use of a novel way of magnetic field tapering, the output efficiency increases from 25% to 39% and the bandwidth increases from 3% to 7.5% compared with the use of a constant magnetic field. Numerical calculations also find that the electron beam reaches a strong bunching state two times before saturation of the radiation field due to the magnetic field tapering.
The stability of ideal magnetohydrodynamic ballooning modes in plasmas with internal transport barriers
Authors: Connor J. W. , Hastie R. J.
Published: April 2004

The stability and spatial structures of short wavelength ideal magnetohydrodynamic ballooning modes (i.e., those modes with moderate to large values of the toroidal mode number, n) that can exist in regions of zero or small magnetic shear are investigated. This is a situation relevant to discharges with internal transport barriers (ITBs). The generic properties of such instabilities are discussed by considering the s–α equilibrium. In regions of low s the ballooning formalism fails for large but finite, values of n. In this limit a complementary approach is developed, based on solving the recurrence relation describing the toroidal coupling of radially localized “modelets” on adjacent mode rational surfaces. This technique extends the stability analysis to lower s and finite n, capturing effects arising from the discreteness of mode rational surfaces. Consideration of equilibrium trajectories in the s–α stability diagram corresponding to profiles of ITB discharges allows one to determine the global stability of such discharges to these modes. It is shown that the stability of ITBs can be parameterized in terms of αmax, the value of the peak α, and the steepness of the barrier pressure profile relative to the shape of the q profile. Inclusion of the stabilizing effects of favorable average curvature at finite aspect ratio, ε, leads to stable high-pressure ITB configurations. The stabilizing influence of low-order rational values of qmin also emerges from the theory. The influences of the bootstrap current and plasma flow shear at ITBs are briefly discussed.
Quantum capping potentials with point charges: A simple QM/MM approach for the calculation of large-molecule NMR shielding tensors
Authors: Moon Seongho , Christiansen Phillip A. , DiLabio Gino A.
Published: April 2004

A simple quantum-mechanics/molecular-mechanics (QM/MM) approach for calculating NMR shielding tensors (σ) is presented. The method involves capping the QM region with quantum capping potentials (QCPs) and representing the MM region with point charges. Test calculations on simple systems without MM charges show that calculated σ values improve relative to the full QM results with increasing distance between the capped bond and chromophore. Calculations on the histidine amino acid and cytosine monophosphate (CMP) nucleic acid show that the use of QCPs with point charges result in mean errors in the isotropic component of σ that are less than 1.6 ppm. The results also reveal that, contrary to previous work, the explicit effect of point charges on σ through coupling with gauge factors, as in the gauge including atomic orbital approach, is minimal for the CMP molecule. The present QM/MM approach for calculating σ is easy to apply and requires no code modification.
Influence of confinement on the vibrational density of states and the Boson peak in a polymer glass
Authors: Jain Tushar S. , de Pablo Juan J.
Published: April 2004

We have performed a normal-mode analysis on a glass forming polymer system for bulk and free-standing film geometries prepared under identical conditions. It is found that for free-standing film glasses, the normal-mode spectrum exhibits significant differences from the bulk glass with the appearance of an additional low-frequency peak and a higher intensity at the Boson peak frequency. A detailed eigenvector analysis shows that the low-frequency peak corresponds to a shear-horizontal mode which is predicted by continuum theory. The peak at higher frequency (Boson peak) corresponds to motions that are correlated over a length scale of approximately twice the interaction site diameter. These observations shed some light on the microscopic dynamics of glass formers, and help explain decreasing fragility that arises with decreasing thickness in thin films.
On the role of block copolymer additives for calcium carbonate crystallization: Small angle neutron scattering investigation by applying contrast variation
Authors: Endo Hitoshi , Schwahn Dietmar , Cölfen Helmut
Published: April 2004

The role of the double-hydrophilic block copolymer poly(ethylen glycol)-block-poly(methacrylic acid) (PEG-b-PMAA) on the morphogenesis of calcium carbonate (CaCO3) was studied by applying the contrast variation small angle neutron scattering technique. The morphology and size of CaCO3 crystals is strongly affected by the addition of PEG-b-PMAA. In order to determine the partial scattering functions of the polymer and CaCO3 mineral, we developed both an experimental and theoretical approach with a sophisticated method of their determination from the scattering intensity. Partial scattering functions give detailed information for each component. In particular, the partial scattering function of the polymer, Spp, shows a monotonic slope with Q−2 to −3 where the scattering vector Q is low (Q<0.01 Å−1), which is a clear evidence that the polymer within the CaCO3 mineral has a mass fractal dimension. The other partial scattering functions reflected the geometry of the CaCO3 particles or the “interaction” of polymer and CaCO3 on a microscopic scale, which leads to a coherent view with Spp.
“Swiss-cheese” polyelectrolyte gels as media with extremely inhomogeneous distribution of charged species
Authors: Vasilevskaya Valentina V. , Aerov Artem A. , Khokhlov Alexei R.
Published: April 2004

“Swiss-cheese” polyelectrolyte gels (i.e., gels containing a regular set of closed spherical pores) are considered as a suitable system for modeling of a medium with extremely inhomogeneous distribution of charged species. It is shown that the inhomogeneous distribution of ions in Swiss-cheese polyelectrolyte gels can be reached simply by immersion of the gels in an aqueous solution of charged species (e.g., low-molecular 1–1 salt or multivalent ions and macroions charged likely to the gel chains). If a polymer gel is kept in such a solution for a long time, the concentration of ions within relatively big voids becomes equal to that in external solution. On the other hand, due to the Donnan effect the ion’s concentration in polymer matrix is always lower than that in external solution. As a result the multivalent ions distribute between water voids and polymer matrix. The extent of this distribution is characterized by partition coefficient kD (determined as ratio kD=nsvoid/nsmat of the concentrations nsvoid and nsmat of ions in water voids and in polymer matrix, correspondingly). It is shown that the partition coefficient kD can be larger than 10 for low-molecular salt, reaches 103 for bivalent ions, and is higher than 106 for tetravalent ions. In the case of polymer macroions the partition coefficient kD tends to infinity. Our calculations show that the lower limit of characteristic scales of heterogeneity (determined by water voids size starting from which the condition of total electroneutrality is fulfilled and effect of partition is the most pronounced) can be equal to tens of nanometers.
Competition between linear and cyclic structures in monochromium carbide clusters CrCn− and CrCn (n=2–8): A photoelectron spectroscopy and density functional study
Authors: Zhai Hua-Jin , Wang Lai-Sheng , Jena P. , Gutsev G. L. , Bauschlicher C. W.
Published: April 2004

Photoelectron spectroscopy (PES) is combined with density functional theory (DFT) to study the monochromium carbide clusters CrCn− and CrCn (n=2–8). Well-resolved PES spectra were obtained, yielding structural, electronic, and vibrational information about both the anionic and neutral clusters. Experimental evidence was observed for the coexistence of two isomers for CrC2−, CrC3−, CrC4−, and CrC6−. Sharp and well-resolved PES spectra were observed for CrCn− (n=4,6,8), whereas broad spectra were observed for CrC5− and CrC7−. Extensive DFT calculations using the generalized gradient approximation were carried out for the ground and low-lying excited states of all the CrCn− and CrCn species, as well as coupled-cluster calculations for CrC2− and CrC2. Theoretical electron affinities and vertical detachment energies were calculated and compared with the experimental data to help the assignment of the ground states and obtain structural information. We found that CrC2− and CrC3− each possess a close-lying cyclic and linear structure, which were both populated experimentally. For the larger CrCn− clusters with n=4, 6, 8, linear structures are the overwhelming favorite, giving rise to the sharp PES spectral features. CrC7− was found to have a cyclic structure. The broad PES spectra of CrC5− suggested a cyclic structure, whereas the DFT results predicted a linear one.
Ab initio quantum dynamics with very weak van der Waals interactions: Structure and stability of small Li2(1Σg+)–(He)n clusters
Authors: Bodo E. , Sebastianelli F. , Gianturco F. A. , Yurtsever E. , Yurtsever M.
Published: April 2004

The potential energy surface (PES) for the interaction between Li2(1Σg+) and He4 has been computed using an accurate, post-Hartree–Fock quantum calculation for its ground electronic state. The orientational anisotropy of the forces and the interplay between repulsive and attractive effects within the PES are analyzed to extract information on the possible existence of bound states in the triatomic system. The structures of a few of the Li2(He)n small clusters are examined by comparing a classical approach with a full quantum one to generate bound configurations and to extract information on the possible spatial arrangements of the smaller clusters via à vis the location of the Li2 dopant. Some significant consequences on the Li2 behavior in larger clusters and droplets are drawn from the above findings.
Equation of state of a seven-dimensional hard-sphere fluid. Percus–Yevick theory and molecular-dynamics simulations
Authors: Robles Miguel , López de Haro Mariano , Santos Andrés
Published: April 2004

Following the work of Leutheusser [Physica A 127, 667 (1984)], the solution to the Percus–Yevick equation for a seven-dimensional hard-sphere fluid is explicitly found. This allows the derivation of the equation of state for the fluid taking both the virial and the compressibility routes. An analysis of the virial coefficients and the determination of the radius of convergence of the virial series are carried out. Molecular-dynamics simulations of the same system are also performed and a comparison between the simulation results for the compressibility factor and theoretical expressions for the same quantity is presented.
A Langevin dynamics study of mobile filler particles in phase-separating binary systems
Authors: Laradji Mohamed
Published: April 2004

The dynamics of phase separation in a simple binary mixture containing mobile filler particles that are preferentially wet by one of the two components is investigated systematically via Langevin simulations in two dimensions. We found that while the filler particles reduce the growth rate of spinodal decomposition, the domain growth remains essentially identical to that of the pure binary mixture. The growth rate diminishes as either the filler particles concentration is increased or their diffusivity is decreased.
Features of the low-temperature creep of a Nb–Ti alloy after large plastic deformations at 77 K
Authors: Aksenov V. K. , Volchok O. I. , Karaseva E. V. , Starodubov Ya. D.
Published: April 2004

The low-temperature (77 K) creep and the corresponding changes in the resistivity of a niobium–titanium alloy subjected to plastic deformation by drawing at 77 K are investigated. It is shown that after large plastic deformations (ε>99%) one observes anomalies of the low-temperature creep which do not appear in tests of samples subjected to low and medium deformations. The creep rate in the transient stage is significantly higher than would follow from the classical ideas about the mechanisms of low-temperature creep (logarithmic law), and the time dependence of the creep deformations is described by a power law, which corresponds to recovery creep. In the creep process oscillations appear on the resistivity curves; these are especially pronounced after drawing in liquid nitrogen. Possible causes of the observed effects are discussed.
Molecular dynamics studies of melting and solid-state transitions of ammonium nitrate
Authors: Velardez Gustavo F. , Alavi Saman , Thompson Donald L.
Published: April 2004

Molecular dynamics simulations are used to calculate the melting point and some aspects of high-temperature solid-state phase transitions of ammonium nitrate (AN). The force field used in the simulations is that developed by Sorescu and Thompson [J. Phys. Chem. A 105, 720 (2001)] to describe the solid-state properties of the low-temperature phase-V AN. Simulations at various temperatures were performed with this force field for a 4×4×5 supercell of phase-II AN. The melting point of AN was determined from calculations on this supercell with voids introduced in the solid structure to eliminate superheating effects. The melting temperature was determined by calculating the density and the nitrogen–nitrogen radial distribution functions as functions of temperature. The melting point was predicted to be in the range 445±10 K, in excellent agreement with the experimental value of 442 K. The computed temperature dependences of the density, diffusion, and viscosity coefficient for the liquid are in good agreement with experiment. Structural changes in the perfect crystal at various temperatures were also investigated. The ammonium ions in the phase-II structure are rotationally disordered at 400 K. At higher temperatures, beginning at 530 K, the nitrate ions are essentially rotationally unhindered. The density and radial distribution functions in this temperature range show that the AN solid is superheated. The rotational disorder is qualitatively similar to that observed in the experimental phase-II to phase-I solid-state transition.
Energetics, transition states, and intrinsic reaction coordinates for reactions associated with O(3P) processing of hydrocarbon materials
Authors: Yan Tianying , Hase William L. , Doubleday Charles
Published: April 2004

Electronic structure calculations based on multiconfiguration wave functions are used to investigate a set of archetypal reactions relevant to O(3P) processing of hydrocarbon molecules and surfaces. These include O(3P) reactions with methane and ethane to give OH plus methyl or ethyl radicals, O(3P)+ethane to give CH3O+CH3, and secondary reactions of the OH product radical with ethane and the ethyl radical. Geometry optimization is carried out with CASSCF/cc-pVTZ for all reactions, and with CASPT2/cc-pVTZ for O(3P)+methane/ethane. Single-point energy corrections are applied with CASPT2, CASPT3, and MRCI+Q with the cc-pVTZ and cc-pVQZ basis sets, and the energies extrapolated to the complete basis set limit (CBL). Where comparison of computed barriers and energies of reaction with experiment is possible, the agreement is good to excellent. The best agreement (within experimental error) is found for MRCI+Q/CBL applied to O(3P)+methane. For the other reactions, CASPT2/CBL and MRCI+Q/CBL predictions differ from experiment by 1–5 kcal/mol for 0 K enthalpies of reaction, and are within 1 kcal/mol of the best-estimate experimental range of 0 K barriers for O(3P)+ethane and OH+ethane. The accuracy of MRCI+Q/CBL is limited mainly by the quality of the active space. CASPT2/CBL barriers are consistently lower than MRCI+Q/CBL barriers with identical reference spaces.
First-principle molecular dynamics of the Berry pseudorotation: Insights on F19 NMR in SF4
Authors: Pavone Michele , Barone Vincenzo , Ciofini Ilaria , Adamo Carlo
Published: April 2004

First-principles [density-functional theory (DFT)] molecular-dynamic simulations of the Berry pseudorotation mechanism in SF4 were performed using the atom-centered density-matrix propagation method. The reaction was monitored by following the chemical shieldings of the fluorine atoms, computed on snapshots along the trajectories. In particular we compared the results obtained using a standard functional based on the generalized gradient approximation with those issuing from its hybrid Hartree–Fock–DFT counterpart using a number of basis sets. Our results show that both the basis set and the functional choice rule the quality of the molecular properties monitored as well as the trajectory over the potential-energy surface.
Two-dimensional Monte Carlo simulations of ionic and nonionic silane self-assembly on hydrophilic surfaces
Authors: Kapila Vivek , Almanza-Workman A. Marcia , Deymier Pierre A. , Raghavan Srini
Published: April 2004

Aqueous chemistries have recently been shown to be useful for the deposition of hydrophobic films of nonionic and cationic silanes on hydrophilic substrates for the prevention of stiction in MEMS. The Monte Carlo method is used to simulate in two dimensions the self-assembly of silane films on a hydrophilic surface. We investigate the impact of charged group in cationic silane on the overall structure of the films. We characterize the film structure with spatial pair correlations at each molecular layer of the deposited films. The simulations reveal long-range correlations for the film of cationic silanes. Based on our two-dimensional simulations, we report an average “most probable” structure for the films of nonionic and cationic silanes.
Solution of quantum Langevin equation: Approximations, theoretical and numerical aspects
Authors: Banerjee Dhruba , Bag Bidhan Chandra , Banik Suman Kumar , Ray Deb Shankar
Published: April 2004

Based on a coherent state representation of noise operator and an ensemble averaging procedure using Wigner canonical thermal distribution for harmonic oscillators, a generalized quantum Langevin equation has been recently developed [Phys. Rev. E 65, 021109 (2002); 66, 051106 (2002)] to derive the equations of motion for probability distribution functions in c-number phase-space. We extend the treatment to explore several systematic approximation schemes for the solutions of the Langevin equation for nonlinear potentials for a wide range of noise correlation, strength and temperature down to the vacuum limit. The method is exemplified by an analytic application to harmonic oscillator for arbitrary memory kernel and with the help of a numerical calculation of barrier crossing, in a cubic potential to demonstrate the quantum Kramers’ turnover and the quantum Arrhenius plot.
Functional evidence for active site location of tetrameric thymidylate synthase X at the interphase of three monomers
Authors: Leduc Damien , Graziani Sébastien , Lipowski Gerard , Marchand Christophe , Le Maréchal Pierre , Liebl Ursula , Myllykallio Hannu
Published: April 2004

Little is known about the catalytic mechanism of the recently discovered ThyX family of flavin-dependent thymidylate synthases that are required for thymidylate (deoxythymidine 5′-monophosphate) synthesis in a large number of microbial species. Using a combination of site-directed mutagenesis and biochemical measurements, we have identified several residues of the
Helicobacter pylori
ThyX protein with crucial roles in ThyX catalysis. By providing functional evidence that the active site(s) of homotetrameric ThyX proteins is formed by three different subunits, our findings suggest that ThyX proteins have evolved through multimerization of inactive monomers. Moreover, because the active-site configurations of ThyX proteins, present in many human pathogenic bacteria, and of human thymidylate synthase ThyA are different, our results will aid in the identification of compounds specifically inhibiting microbial growth.
Food and residential care in old age
Authors: Lyon Phil , Kettunen Tuula , Colquhoun Anne
Published: April 2004

In Scotland and Finland, a relatively small proportion of older people are in some form of residential care, but their numbers are not insubstantial given generally increased longevity. Moreover, those currently in residential care tend to be among the most vulnerable survivors of their generation. Residential care for older people has always been something of a paradox. The state has extensively recognised the vulnerability of those who can no longer care for themselves, or be cared for by their partner and family. However, provision is seldom adequate for the scale of demand and even commercial provision is characterised by low staffing ratios and unmet training needs. This paper outlines the development of Leonardo funded training materials for use across the European Union.
The effect of organisational culture and leadership style on job satisfaction and organisational commitment
Authors: Lok Peter , Crawford John
Published: April 2004

This study examined the effects of organisational culture and leadership styles on job satisfaction and organisational commitment in samples of Hong Kong and Australian managers. Statistically significant differences between the two samples were found for measures of innovative and supportive organizational cultures, job satisfaction and organizational commitment, with the Australian sample having higher mean scores on all these variables. However, differences between the two samples for job satisfaction and commitment were removed after statistically controlling for organizational culture, leadership and respondents' demographic characteristics. For the combined samples, innovative and supportive cultures, and a consideration leadership style, had positive effects on both job satisfaction and commitment, with the effects of an innovative culture on satisfaction and commitment, and the effect of a consideration leadership style on commitment, being stronger in the Australian sample. Also, an “initiating Structure” leadership style had a negative effect on job satisfaction for the combined sample. Participants' level of education was found to have a slight negative effect on satisfaction, and a slight positive effect on commitment. National culture was found to moderate the effect of respondents' age on satisfaction, with the effect being more positive amongst Hong Kong managers.
Efficacy of role‐playing pedagogy in training leaders: some reflections
Authors: Agboola Sogunro Olusegun
Published: April 2004

As the need is rife for today's leaders to make swift and perfect decisions, they need to learn critical thinking and interpersonal skills as quickly as they can. The traditional pedagogical techniques of training lack the potentiality to make these happen. Not only are they rigorous, and less dynamic, but also they are less learner‐centered, less experiential, and often predispose learners to evaluation anxiety situations. The method of role‐playing differs in many unique ways. Its ability to induce participants to quick understanding notwithstanding, it also has the potential to transform theoretical concepts into an experiential format. In all the scenarios presented in this paper, role‐playing has presented itself as one of the most promising training techniques today. This paper attempts to reflect on the efficacy of role‐playing as an effective pedagogical technique. Implications for practice and research are also discussed.
Place attachment and sense of belonging
Authors: Inalhan Göksenin , Finch Edward
Published: April 2004

Examines the concept of “place attachment” as defined in various disciplines and develops an effective conceptual approach that can be applied to facilities management. Describes the development of a model‐matchmaking process adapted from Passini's model of cognitive mapping. Findings that the emergence of the new economy is undermining our ability to form attachments with people, places and companies. However, one of the unintended effects of this is that it has strengthened the value of place and aroused a longing for community. Moreover, loyalty to an organisation is increasingly determined by social and place attachment. Proposes that further research needs to be undertaken to “engineer out” the negative impacts of flexibility associated with loss of place. States that place attachment presents a challenging view of the world that is contrary to all the received wisdom in facilities management, where flexibility has always assumed an unchallenged position in relation to buildings and people. Concludes that this research area presents many pragmatic design and operational questions for facilities managers.
Quality service in the international hotel sector
Authors: Maxwell Gill , Watson Sandra , Quail Samantha
Published: April 2004

This paper analyses the nature of, and relationship between, a quality service initiative and the concept of strategic human resource development. Hilton International is the case study used for this analysis. The principal finding is that the quality initiative is acting as a catalyst for a strategic approach to human resource development to emerge in the case organisation. However although many of the factors identified with the concept of strategic human resource development are evidenced, it is proposed that the standards set by academics in the field of human resource development may be too aspirational for the hotel sector.
People management practices in the public health sector
Authors: Stanton Pauline , Bartram Timothy , Harbridge Raymond
Published: April 2004

This study investigates the impact on human resource management (HRM) practices in the public health sector in Victoria, Australia of two different government policy environments. First, it explores the Liberal Coalition Government's decentralisation of public health sector management, from 1992‐1999 and second, the Labor Government's recentralisation of employment relations in the sector. This paper focuses on three dimensions. First, it outlines the main policy directions impacting on people management in the health care sector under the different governments. Second, it explores the impact of these policy directions on HRM. Third, it discusses the implications for future directions of the practice of HRM in the public hospital sector.
Buyer‐seller relationships and information sources in an e‐commerce world
Authors: Deeter‐Schmelz Dawn R. , Norman Kennedy Karen
Published: April 2004

In the environment of business‐to‐business e‐commerce, both buyers and sellers are uncertain about their roles. Questions abound. What is the role of the Internet in buyer‐seller relationships, and what will be the interface between the Internet and the salesforce as information sources? Data collected from purchasing professionals suggest that traditional information sources, including suppliers’ salespeople, are more useful than the Internet at the present time. Moreover, findings indicate that the Internet plays almost no role in supplier selection decisions and only a moderate role in ongoing buyer‐seller relationships. Additionally, in relationships characterized by high levels of information exchange, trust, cooperation, and/or adaptations, the Internet appears to play a less important role. Based on these findings, implications for practitioners and researchers are discussed.
Effects of price premium and product type on the choice of cause‐related brands: a Singapore perspective
Authors: Subrahmanyan Saroja
Published: April 2004

This exploratory study investigates whether product type, utilitarian versus hedonic, affects consumers' likelihood of choosing a brand linked to a cause. The sample consists of 128 young Chinese Singaporeans. Unlike prior research done in Western countries, the respondents in this study were more likely to buy cause‐linked brands for practical than for hedonic products. They were also more likely to pay a price premium for cause‐linked practical products. This difference is attributed to the Confucian values that are espoused by the Chinese. Additionally, finds that specifying the amount donated to the cause increases the likelihood of purchasing cause‐linked brands that are priced at 10 to 25 percent premiums over comparable alternatives. Discusses implications for marketers and future research directions.
Provider Contact with Families of Adults with Severe Mental Illness: Taking a Closer Look
Authors: Marshall Tina , Solomon Phyllis
Published: April 2004

This exploratory study examined the frequency and nature of providers' contact with families of persons with severe mental illness. Fifty‐nine providers in six community mental health programs completed a self‐administered survey. A subsample of 8 providers also completed two in‐depth interviews. Although most providers had some family contact, the contact was restricted to a small percent of their caseloads. The nature of contact that providers have with families is generally limited by their professional role. Best practice guidelines for the treatment of mental illness and agency administrators responsible for instituting these guidelines will need to clarify the types of providers who are expected to implement various aspects of family involvement.
Changes of the Secondary Structure of the 5′ End of the Sindbis Virus Genome Inhibit Virus Growth in Mosquito Cells and Lead to Accumulation of Adaptive Mutations
Authors: Fayzulin Rafik , Frolov Ilya
Published: April 2004

Both the 5′ end of the Sindbis virus (SIN) genome and its complement in the 3′ end of the minus-strand RNA synthesized during virus replication serve as parts of the promoters recognized by the enzymes that comprise the replication complex (RdRp). In addition to the 5′ untranslated region (UTR), which was shown to be critical for the initiation of replication, another 5′ sequence element, the 51-nucleotide (nt) conserved sequence element (CSE), was postulated to be important for virus replication. It is located in the nsP1-encoding sequence and is highly conserved among all members of the
Alphavirus
genus. Studies with viruses containing clustered mutations in this sequence demonstrated that this RNA element is dispensable for SIN replication in cells of vertebrate origin, but its integrity can enhance the replication of SIN-specific RNAs. However, we showed that the same mutations had a deleterious effect on virus replication in mosquito cells. SIN with a mutated 51-nt CSE rapidly accumulated adaptive mutations in the nonstructural proteins nsP2 and nsP3 and the 5′ UTR. These mutations functioned synergistically in a cell-specific manner and had a stimulatory effect only on the replication of viruses with a mutated 51-nt CSE. Taken together, the results suggest the complex nature of interactions between nsP2, nsP3, the 5′ UTR, and host-specific protein factors binding to the 51-nt CSE and involved in RdRp formation. The data also demonstrate an outstanding potential of alphaviruses for adaptation. Within one passage, SIN can adapt to replication in cells of a vertebrate or invertebrate origin.
Treatment of Transmissible Spongiform Encephalopathy by Intraventricular Drug Infusion in Animal Models
Authors: Doh-ura Katsumi , Ishikawa Kensuke , Murakami-Kubo Ikuko , Sasaki Kensuke , Mohri Shirou , Race Richard , Iwaki Toru
Published: April 2004

The therapeutic efficacy of direct drug infusion into the brain, the target organ of transmissible spongiform encephalopathies, was assessed in transgenic mice intracerebrally infected with 263K scrapie agent. Pentosan polysulfate (PPS) gave the most dramatic prolongation of the incubation period, and amphotericin B had intermediate effects, but antimalarial drugs such as quinacrine gave no significant prolongation. Treatment with the highest dose of PPS at an early or late stage of the infection prolonged the incubation time by 2.4 or 1.7 times that of the control mice, respectively. PPS infusion decreased not only abnormal prion protein deposition but also neurodegenerative changes and infectivity. These alterations were observed within the brain hemisphere fitted with an intraventricular infusion cannula but not within the contralateral hemisphere, even at the terminal disease stage long after the infusion had ended. Therapeutic effects of PPS were also demonstrated in mice infected with either RML agent or Fukuoka-1 agent. However, at doses higher than that providing the maximal effects, intraventricular PPS infusion caused adverse effects such as hematoma formation in the experimental animals. These findings indicate that intraventricular PPS infusion might be useful for the treatment of transmissible spongiform encephalopathies in humans, providing that the therapeutic dosage is carefully evaluated.
Prediction and Identification of a Permissive Epitope Insertion Site in the Vesicular Stomatitis Virus Glycoprotein
Authors: Schlehuber Lisa D. , Rose John K.
Published: April 2004

We developed a rational approach to identify a site in the vesicular stomatitis virus (VSV) glycoprotein (G) that is exposed on the protein surface and tolerant of foreign epitope insertion. The foreign epitope inserted was the six-amino-acid sequence ELDKWA, a sequence in a neutralizing epitope from human immunodeficiency virus type 1. This sequence was inserted into six sites within the VSV G protein (Indiana serotype). Four sites were selected based on hydrophilicity and high sequence variability identified by sequence comparison with other vesiculovirus G proteins. The site showing the highest variability was fully tolerant of the foreign peptide insertion. G protein containing the insertion at this site folded correctly, was transported normally to the cell surface, had normal membrane fusion activity, and could reconstitute fully infectious VSV. The virus was neutralized by the human 2F5 monoclonal antibody that binds the ELDKWA epitope. Additional studies showed that this site in G protein tolerated insertion of at least 16 amino acids while retaining full infectivity. The three other insertions in somewhat less variable sequences interfered with VSV G folding and transport to the cell surface. Two additional insertions were made in a conserved sequence adjacent to a glycosylation site and near the transmembrane domain. The former blocked G-protein transport, while the latter allowed transport to the cell surface but blocked membrane fusion activity of G protein. Identification of an insertion-tolerant site in VSV G could be important in future vaccine and targeting studies, and the general principle might also be useful in other systems.
Murine Gammaherpesvirus 68 Lacking gp150 Shows Defective Virion Release but Establishes Normal Latency In Vivo
Authors: de Lima Brigitte D. , May Janet S. , Stevenson Philip G.
Published: April 2004

All gammaherpesviruses encode a virion glycoprotein positionally homologous to Epstein-Barr virus gp350. These glycoproteins are thought to be involved in cell binding, but little is known of the roles they might play in the whole viral replication cycle. We have analyzed the contribution of murine gammaherpesvirus 68 (MHV-68) gp150 to viral propagation in vitro and host colonization in vivo. MHV-68 lacking gp150 was viable and showed normal binding to fibroblasts and normal single-cycle lytic replication. Its capacity to infect glycosaminoglycan (GAG)-deficient CHO-K1 cells and NS0 and RAW264.7 cells, which express only low levels of GAGs, was paradoxically increased. However, gp150-deficient MHV-68 spread poorly through fibroblast monolayers, with reduced cell-free infectivity, consistent with a deficit in virus release. Electron microscopy showed gp150-deficient virions clustered on infected-cell plasma membranes. MHV-68-infected cells showed reduced surface GAG expression, suggesting that gp150 prevented virions from rebinding to infected cells after release by making MHV-68 infection GAG dependent. Surprisingly, gp150-deficient viruses showed only a transient lag in lytic replication in vivo and established normal levels of latency. Cell-to-cell virus spread and the proliferation of latently infected cells, for which gp150 was dispensable, therefore appeared to be the major route of virus propagation in an infected host.