bluuebunny/crossref_metadata_2025 huggingface dataset:
Observations of the turbulence in the scrape-off-layer of Alcator C-Mod and comparisons with simulation
Authors: Terry J. L. , Zweben S. J. , Hallatschek K. , LaBombard B. , Maqueda R. J. , Bai B. , Boswell C. J. , Greenwald M. , Kopon D. , Nevins W. M. , Pitcher C. S. , Rogers B. N. , Stotler D. P. , Xu X. Q.
Published: April 2003

The intermittent turbulent transport in the scrape-off-layer (SOL) of Alcator C-Mod [I.H. Hutchinson, R. Boivin, P.T. Bonoli et al., Nucl. Fusion 41, 1391 (2001)] is studied experimentally by imaging with a very high density of spatial measurements. The two-dimensional structure and dynamics of emission from a localized gas puff are observed, and intermittent features (also sometimes called “filaments” or “blobs”) are typically seen. The characteristics of the spatial structure of the turbulence and their relationship to the time-averaged SOL profiles are discussed and compared with those measured on the National Spherical Torus Experiment [M. Ono, S. M. Kaye, Y.-K. M. Pong et al., Nucl. Fusion 40, 557 (2000)]. The experimental observations are compared also with three-dimensional nonlinear numerical simulations of edge turbulence. Radial profiles of the poloidal wave number spectra and the poloidal scale length from the simulations are in reasonable agreement with those obtained from the experimental images, once the response of the optical system is accounted for. The resistive ballooning mode is the dominant linear instability in the simulations. The ballooning character of the turbulence is also consistent with fluctuation measurements made at the inboard and outboard midplane, where normalized fluctuation levels are found to be about 10 times smaller on the inboard side. For discharges near the density limit, turbulent structures are seen on closed flux surfaces.
Direct-drive cryogenic target implosion performance on OMEGA
Authors: Sangster T. C. , Delettrez J. A. , Epstein R. , Glebov V. Yu. , Goncharov V. N. , Harding D. R. , Knauer J. P. , Keck R. L. , Kilkenny J. D. , Loucks S. J. , Lund L. D. , McCrory R. L. , McKenty P. W. , Marshall F. J. , Meyerhofer D. D. , Morse S. F. B. , Regan S. P. , Radha P. B. , Roberts S. , Seka W. , Skupsky S. , Smalyuk V. A. , Sorce C. , Soures J. M. , Stoeckl C. , Thorp K. , Frenje J. A. , Li C. K. , Petrasso R. D. , Séguin F. H. , Fletcher K. A. , Padalino S. , Freeman C. , Izumi N. , Koch J. A. , Lerche R. A. , Moran M. J. , Phillips T. W. , Schmid G. J.
Published: April 2003

Layered and characterized cryogenic D2 capsules have been imploded using both low- and high-adiabat (α, the ratio of the electron pressure to the Fermi-degenerate pressure) pulse shapes on the 60-beam OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] at the Laboratory for Laser Energetics (LLE). These experiments measure the sensitivity of the direct-drive implosion performance to parameters such as the inner-ice-surface roughness, the adiabat of the cryogenic fuel during the implosion, the laser power balance, and the single-beam nonuniformity. The goal of the direct-drive program at LLE is to demonstrate a high neutron-averaged fuel ρR at a significant fraction of the predicted one-dimensional (1-D) neutron yield using an energy-scaled, low-adiabat (α∼3) ignition pulse shape driving a hydrodynamically scaled deuterium–tritium ignition capsule. New results are reported from implosions of ∼920-μm-diam, thin (∼5 μm) polymer shells containing 100 μm D2-ice layers with characterized inner-surface ice roughness of 3–12 μm rms. These capsules have been imploded using ∼17–23 kJ of 351 nm laser light with a beam-to-beam rms energy imbalance of less than 5% and full beam smoothing [1 THz bandwidth, two-dimensional (2-D) smoothing by spectral dispersion and polarization smoothing]. Near-1-D performance has been measured for a high-adiabat (α∼25) drive pulse, and the implosion performance with a low-adiabat (α∼4) pulse is in agreement with 2-D hydrocode predictions.
Determination of liquid–solid transition using histogram reweighting method and expanded ensemble simulations
Authors: Chang Jaeeon , Sandler Stanley I.
Published: April 2003

Using the combination of the histogram reweighting and expanded ensemble simulation methods a new generic algorithm for predicting liquid–solid equilibria is proposed. This method avoids the fitting procedures and numerical integration previously required to obtain the equation of state and free energy. Using the expanded ensemble simulation we calculate the free energy difference between hard-sphere crystal and the corresponding Einstein crystal without the need to constrain the center of mass of the system. The liquid–solid equilibria for hard-sphere systems of varying size up to 1372 particles are studied with NpT Monte Carlo simulation and histogram reweighting. We find only a slight size dependence of coexistence properties with this method, and the limit for the infinitely large system is easily and accurately determined.
Distributional Borel summability for vacuum polarization by an external electric field
Authors: Caliceti Emanuela
Published: April 2003

It is proved that the divergent perturbation expansion for the vacuum polarization by an external constant electric field in the pair production sector is Borel summable in the distributional sense.
Global extended magnetohydrodynamic studies of fast magnetic reconnection
Authors: Breslau J. A. , Jardin S. C.
Published: April 2003

Recent experimental and theoretical results have led to two lines of thought regarding the physical processes underlying fast magnetic reconnection. One is based on the traditional Sweet–Parker model but replaces the Spitzer resistivity with an enhanced resistivity caused by electron scattering by ion acoustic turbulence. The other includes the finite gyroradius effects that enter Ohm’s law through the Hall and electron pressure gradient terms. A two-dimensional numerical study, conducted with a new implicit parallel two-fluid code, has helped to clarify the similarities and differences in predictions between these two models. The former yields resistivity-dependent reconnection with a thick, moderate-aspect-ratio current sheet. If the sheet thickness is less than or comparable to the ion skin depth, it is verified that the Hall effect will predominate [Shay et al., Geophys. Res. Lett. 26, 2163 (1999)], producing true fast reconnection with a microscopic current sheet of unit aspect ratio and a distorted out-of-plane magnetic field [Mandt et al., Geophys. Res. Lett. 21, 73 (1994)].
Bi-Hamiltonian partially integrable systems
Authors: Giachetta G. , Mangiarotti L. , Sardanashvily G.
Published: April 2003

Given a first order dynamical system possessing a commutative algebra of dynamical symmetries, we show that, under certain conditions, there exists a Poisson structure on an open neighborhood of its regular (not necessarily compact) invariant manifold which makes this dynamical system into a partially integrable Hamiltonian system. This Poisson structure is by no means unique. Bi-Hamiltonian partially integrable systems are described in some detail. As an outcome, we state the conditions of quasiperiodic stability (the KAM theorem) for partially integrable Hamiltonian systems.
Electron acceleration by a plasma wave in a sheared magnetic field
Authors: Singh K. P. , Gupta V. L. , Bhasin Lalita , Tripathi V. K.
Published: April 2003

Using a relativistic two-dimensional single particle code, the acceleration of electrons by a plasma wave, in the presence of a sheared magnetic field (a slab model for the azimuthal magnetic field) is studied. The plasma wave propagates along z-axis while its amplitude profile in the transverse x-direction is Gaussian, E=−∇φ, φ=A/ke−x2/r0′2 sin(ωt−kz+θ). The magnetic field is taken as Bs=−(Bs0x/r0)ŷe−x2/r02. The electrons that originate off the axis with finite velocity execute oscillatory trajectories in the x-z plane, due to the magnetic field. As they pass through the axial region, the plasma wave accelerates them. The electrons that originate at x0=2, z=0, with vx0=0.1, vz0=0.9, attain maximum energy Emax≈35 MeV for dimensionless plasma wave amplitude ap=eA/m0ωc≈0.6, b0=eBs0/m0ωc≈0.6 , where −e and m0 are the electronic charge and rest mass, respectively.
Stability of Beltrami flows
Authors: Yoshida Z. , Ohsaki S. , Ito A. , Mahajan S. M.
Published: April 2003

Stability of a special class of flows (which we call Beltrami flows) can be analyzed by invoking a constant of motion that bounds the energy of perturbations. This stability condition (a sufficient condition) suppresses any instability including nonexponential (secular) growth due to non-Hermiticity; it also prohibits nonlinear evolution to a large amplitude. The key to prove is the “coerciveness” of the constant of motion in the topology of the energy norm. The theory has been applied for an ideal (nondissipative) magnetized plasma.
Spectral dependence of the squared average optical transition matrix element associated with hydrogenated amorphous silicon
Authors: O’Leary Stephen Karrer
Published: April 2003

Using an empirical model for the density of states functions, in conjunction with an elementary model for the optical transition matrix elements, the spectral dependence of the squared average optical transition matrix element associated with hydrogenated amorphous silicon was evaluated. It was predicted that this squared average matrix element saturates at and beyond the mobility gap, decreases sharply just below the mobility gap as the photon energy is diminished, and then saturates at sufficiently low photon energies. The value of the squared average optical transition matrix element at low photon energies depends on the density of localized electronic states. The results suggest that a careful experimental measurement of the spectral dependence of this matrix element will provide one with a direct means of determining the position of the mobility gap of this semiconductor.
Current-induced magnetization switching in magnetic tunnel junctions
Authors: Liu Yaowen , Zhang Zongzhi , Freitas P. P. , Martins J. L.
Published: April 2003

Current-induced magnetization switching (CIMS) in low-resistance magnetic tunnel junctions was shown at average critical current densities (Jc=1.33×106 A/cm2). When large vertical currents pass through the junctions, spin-transfer torque, and vortex fields can rotate the magnetization of the free layer from the initial parallel state to a vortex state, resulting in 10.8% CIMS resistance change at zero-bias current, which is about half of the resistance change (22%) induced when switching is created by an external field. A micromagnetic simulation including the spin-transfer torque and the vortex field correctly predicts the critical negative-current-inducing switching from the parallel state into the vortex state, but fails to explain the reverse switching from the vortex state into the parallel state at an approximately symmetric positive critical current. Lead fields were analyzed and found to be not the cause of the observed switching. The very small dependence of the switching currents on an external magnetic field suggests the existence of hot-spots where local current densities may be much larger.
Effect of ac susceptibility in superconductors on magnetic shielding
Authors: Maruyama M. , Hidaka M. , Satoh T.
Published: April 2003

We have theoretically studied the effect of ac susceptibility in superconductors on magnetic shielding. Our recent study of measured wave form distortion observed in a high-Tc superconductor sampler system suggests that the magnetic field leaks into the sampler circuit through the YBa2Cu3O7−x ground plane when an ac magnetic field is applied. The occurrence of such magnetic leakage can be explained by complex susceptibility in the ground plane because a shielding magnetic field with a phase shifted due to an imaginary part of the susceptibility cannot cancel an applied ac magnetic field completely. A simple calculation shows that the residual magnetic field should have an advanced phase of 45°–90°, which coincides with the results obtained in the sampler system.
Nanotomography based on double asymmetrical Bragg diffraction
Authors: Stampanoni Marco , Borchert Gunther , Abela Rafael , Rüegsegger Peter
Published: April 2003

Nondestructive investigations at ultrahigh spatial resolution can be carried out with synchrotron-based x-ray computer tomography. The performance of presently used detectors is restricted by scintillation properties, optical light transfer and charge coupled device granularity to a limit of 1 μm spatial resolution and efficiency of a few percent. A recently developed detector, called Bragg magnifier, exploits double asymmetrical Bragg diffraction to efficiently produce hard x-ray images with magnification factors up to 100×100 and pixel size of less than 200×200 nm2. Combining it with tomography, we obtained full volumetric information of a sample with spatial resolution well below 1 μm in less than 40 min.
Varistor action in zinc oxide suspension
Authors: Negita K. , Yamaguchi T. , Tsuchie T. , Shigematsu N.
Published: April 2003

In a suspension composed of zinc oxide (ZnO) particles and silicone oil, it is found that the current density dramatically increases above a specific electric field (break down field Eb). In ac measurement, the nonlinear coefficient (α), which characterizes the relationship between current density J and the electric field E as J∝Eα, changes from ∼1 to ∼30 when increasing the electric field through Eb. On the basis of the α value, temperature dependence of Eb, etc., the mechanism of the fluid varistor is briefly discussed.
Microscopic superelastic behavior of a nickel-titanium alloy under complex loading conditions
Authors: Ni Wangyang , Cheng Yang-Tse , Grummon David S.
Published: April 2003

The microscopic superelastic behavior of a nickel-titanium (NiTi) alloy has been studied by instrumented indentation experiments using both spherical and pyramidal (e.g., Berkovich) diamond indenters. The indentation load–displacement curves for a superelastic NiTi and an annealed copper were obtained under a range of indentation conditions. We show that indentation-induced superelasticity exists under both spherical and pyramidal indenters, which may be exploited for many applications, ranging from microelectromechanical systems to surface engineering.
Carrier scattering induced by thickness fluctuation of silicon-on-insulator film in ultrathin-body metal–oxide–semiconductor field-effect transistors
Authors: Uchida Ken , Takagi Shin-ichi
Published: April 2003

We demonstrate that carrier scattering induced by the thickness fluctuation of a silicon-on-insulator (SOI) film reduces electron mobility in ultrathin-body metal–oxide–semiconductor field-effect transistors with SOI thickness, TSOI, of less than 4 nm at room temperature and is the dominant scattering mechanism at low temperatures. The thickness fluctuation of a nanoscaled SOI film induces large potential variations due to the difference of quantum-confinement effects from one part to another, and thus carrier scattering potentials are formed in the channel. It is shown that experimental electron mobility follows the theoretical TSOI dependence and the expected temperature dependence of the scattering induced by SOI thickness fluctuation.
Increasing shear force microscopy scanning rate using active quality-factor control
Authors: Antognozzi M. , Szczelkun M. D. , Humphris A. D. L. , Miles M. J.
Published: April 2003

The use of an active quality-factor control device has been demonstrated to increase the scanning rate of a shear force microscope by lowering the quality factor of the oscillating probe. Shear force microscopy (often used in combination with scanning near-field optical microscopy) requires slow scanning rates due to the long (>1 ms) time constant of the oscillating element (optical fiber or tuning fork). By electronically reducing the quality factor of the probe, it was possible to tune the time constant and correspondingly reduce the overall scanning time by a factor of 4. It was also seen that probes with high quality factors could manifest an unstable behavior; by reducing the quality factor of the probe, it was possible to increase the signal-to-noise ratio and so improve the imaging resolution. Deoxyribonucleic acid molecules deposited onto mica and imaged in air were used to demonstrate the technique.
Quantifying the financial impact of IT security breaches
Authors: Garg Ashish , Curtis Jeffrey , Halper Hilary
Published: April 2003

Internet security is a pervasive concern for all companies. However, developing the business case to support investments in IT security has been particularly challenging because of difficulties in precisely quantifying the economic impact of a breach. Previous studies have attempted to quantify the magnitude of losses resulting from a breach in IT security, but reliance on self‐reported company data has resulted in widely varying estimates of limited credibility. Employing an event study methodology, this study offers an alternative approach and more rigorous evaluation of breaches in IT security. This attempt has revealed several new perspectives concerning the market reaction to IT security breaches. A final component of the study is the extension of the analysis to incorporate eSecurity vendors and a fuller exploration of market reactions before and after the denial of service attacks of February 2000. The key takeaway for corporate IT decision makers is that IT security breaches are extremely costly, and that the stock market has already factored in some level of optimal IT security investment by companies.
Arresting and releasing Staphylococcal α‐hemolysin at intermediate stages of pore formation by engineered disulfide bonds
Authors: Kawate Toshimitsu , Gouaux Eric
Published: April 2003

α‐Hemolysin (αHL) is secreted by Staphylococcus aureus as a water‐soluble monomer that assembles into a heptamer to form a transmembrane pore on a target membrane. The crystal structures of the LukF water‐soluble monomer and the membrane‐bound α‐hemolysin heptamer show that large conformational changes occur during assembly. However, the mechanism of assembly and pore formation is still unclear, primarily because of the difficulty in obtaining structural information on assembly intermediates. Our goal is to use disulfide bonds to selectively arrest and release αHL from intermediate stages of the assembly process and to use these mutants to test mechanistic hypotheses. To accomplish this, we created four double cysteine mutants, D108C/K154C (αHL‐A), M113C/K147C (αHL‐B), H48C/ N121C (αHL‐C), I5C/G130C (αHL‐D), in which disulfide bonds may form between the pre‐stem domain and the β‐sandwich domain to prevent pre‐stem rearrangement and membrane insertion. Among the four mutants, αHL‐A is remarkably stable, is produced at a level at least 10‐fold greater than that of the wild‐type protein, is monomeric in aqueous solution, and has hemolytic activity that can be regulated by the presence or absence of reducing agents. Cross‐linking analysis showed that αHL‐A assembles on a membrane into an oligomer, which is likely to be a heptamer, in the absence of a reducing agent, suggesting that oxidized αHL‐A is halted at a heptameric prepore state. Therefore, conformational rearrangements at positions 108 and 154 are critical for the completion of αHL assembly but are not essential for membrane binding or for formation of an oligomeric prepore intermediate.
Improving the Aero-Thermal Characteristics of Turbomachinery Cascades
Authors: Manna Marcello , Tuccillo Raffaele
Published: April 2003

The paper presents the application of an optimization procedure to the aero-thermal design of high performance turbomachinery cascades. The blade profiles are parameterized with third-order Bezier polynomials for the pressure and suction sides, and quadratic functions for the leading and trailing edges, according to the composite curve approach. Evidence is given that fairly complicated blade shapes are well approximated by the present parameterization. The method is applied to an existing nozzle guide vane for which extensive and detailed experimental data are available, with the objective of decreasing in an integral sense the thermal load, maintaining or increasing the blade efficiency and the aerodynamic load. The results demonstrate that, despite the excellence of the initial design, there is room for improvements.
QUANTUM GRAVITY AT THE PLANCK LENGTH
Authors: POLCHINSKI JOSEPH
Published: April 2003

I describe our understanding of physics near the Planck length, in particular the great progress of the last four years in string theory. The lectures were presented at the 1998 SLAC Summer Institute.
QUANTUM EVOLUTION IN SPACE–TIME FOAM
Authors: GARAY LUIS J.
Published: April 2003

In this work, I review some aspects concerning the evolution of quantum low-energy fields in a foamlike space–time, with involved topology at the Planck scale but with a smooth metric structure at large length scales, as follows. Quantum gravitational fluctuations may induce a minimum length thus introducing an additional source of uncertainty in physics. The existence of this resolution limit casts doubts on the metric structure of space–time at the Planck scale and opens a doorway to nontrivial topologies, which may dominate Planck scale physics. This foamlike structure of space–time may show up in low-energy physics through loss of quantum coherence and mode-dependent energy shifts, for instance, which might be observable. Space–time foam introduces non-local interactions that can be modeled by a quantum bath, and low-energy fields evolve according to a master equation that displays such effects. Similar laws are also obtained for quantum mechanical systems evolving according to good real clocks, although the underlying Hamiltonian structure in this case establishes serious differences among both scenarios.
GLUON CONDENSATE AND BEYOND
Authors: ZAKHAROV V. I.
Published: April 2003

We review briefly and in retrospect the development which brought about the QCD sum rules based on introduction of the gluon condensate (M. A. Shifman, A. I. Vainshtein, and V. I. Zakharov (1978)).
INTERVAL METHODS IN KNOWLEDGE REPRESENTATION
Authors: KREINOVICH VLADIK
Published: April 2003

This section is maintained by Vladik Kreinovich. Please send your abstracts (or copies of papers that you want to see reviewed here) to vladik@cs.utep.edu, or by regular mail to: Vladik Kreinovich, Department of Computer Science, University of Texas at El Paso, El Paso, TX 79968, USA.
STUDY OF LOW-FREQUENCY EXCESS NOISE IN Ga-POLARITY GaN EPITAXIAL LAYERS
Authors: XIE J. Q. , FONG W. K. , LEUNG B. H. , ZHU C. F. , SURYA C. , WONG K. H.
Published: April 2003

We report detailed investigations of low-frequency excess noise in Ga -polarity GaN thin films deposited by RF-plasma assisted molecular beam epitaxy. The noise properties of the GaN thin films deposited with and without the intermediate-temperature buffer layers (ITBL) are studied in detailed to examine the effects of the ITBL on the noise. Substantial reduction in the flicker noise levels are observed for samples grown on ITBLs with a Hooge parameter of 3×10-4, which is believed to be the lowest, to date, reported for GaN material. At low-temperatures, Lorentzian bumps originating from the generation-recombination processes are observed. Detailed studies of the temperature dependencies of the voltage noise power spectra have led to the formulation of a model for the observed low-frequency fluctuations. The model stipulates that the phenomenon arises from the thermally activated trapping and detrapping of carriers. The process results in the correlated fluctuations in the carrier number and the Coulombic scattering rate. Quantitative computation shows that number fluctuation dominates in our samples. Numerical evaluation of the deep-levels indicates substantial reduction in the trap density for the Ga -polarity GaN films.
STOCHASTIC RESONANCE IN A BROWNIAN RATCHET
Authors: ALLISON ANDREW , ABBOTT DEREK
Published: April 2003

We present evidence to support the idea that Stochastic Resonance (SR) and Brownian Ratchets (BR) share underlying physical principles. We examine the special case of a discrete-time ratchet, called Parrondo's games, and show that the addition of noise increases the rate of flow in the ratchet up to a certain point, after which the addition of further noise causes the rate of flow of decrease. We argue that the rate of flow of particles in a BR is analogous to the rate of flow of information in the case of SR.
Magnetic and Gas-Occlusion Properties and Catalytic Activity of Microporous Materials: Dinuclear Ruthenium(II,II) Dicarboxylates
Authors: Ohmura Tetsushi , Mori Wasuke , Hiraga Hiroki , Ono Masato , Nishimoto Yuko
Published: April 2003

A new series of dinuclear ruthenium(II,II) dicarboxylates, but not dinuclear ruthenium(II,III) dicarboxylates, have been prepared. Dinuclear ruthenium(II,II) dicarboxylates, which have a regular two- or three-dimensional network structure, occlude large amounts of gas. The maximum amount of N2 gas that can be occluded by these complexes is 1.0–1.7 moles per mole of ruthenium atoms, indicating the presence of a large number of micropores. These complexes exhibited pore volume-dependent catalytic activity for the hydrogenation of ethylene.
A description of cloud production by non‐uniformly distributed processes
Authors: Bushell Andrew C. , Wilson Damian R. , Gregory David
Published: April 2003

Prognostic cloud‐fraction and condensate equations, for the case in which a source injects condensate‐laden, saturated air into a volume, are derived by considering the response of a general distribution of thermodynamic variables within the volume. These prognostic equations are compared with those derived by assuming that condensate is added uniformly to both clear and cloudy parts of the region. For non‐uniform forcing, the local condensate mixing ratio associated with the condensate source is important in controlling the rate of change of cloud fraction and in‐cloud condensate. For the case of a convective condensate source, the cloud‐fraction equation is contrasted with previously derived alternatives. Lastly, the validity of a prognostic equation for cloud fraction is discussed in the light of a different approach in which the moments of a distribution of thermodynamic variables are specified from prognostic equations and used to calculate cloud fraction and condensate diagnostically. © Crown copyright, 2003. Royal Meteorological Society
Photorefractive Performance Enhancement in Polymer Dispersions of Nanosized Crystalline Domains
Authors: Termine R. , Aiello I. , Dattilo D. , Ghedini M. , Golemme A.
Published: April 2003

Photorefractive polymeric nanosized dispersions of crystalline materialswith high dynamic range have been developed using controlled phase‐separation techniques. Orientational birefringence is induced by internal electric fields via the dielectric anisotropy of crystalline domains, rather than through the usual reorientation of molecular dipoles. This more efficient mechanism can increase photorefractive performance by two orders of magnitude and can in principle be applied to optimize other materials for a variety of applications, including medical imaging and image processing.
A Strong Correlation Between the Hole Mobility and Silicon Chain Length in Oligosilane Self‐Organized Thin Films
Authors: Okumoto H. , Yatabe T. , Richter A. , Peng J. , Shimomura M. , Kaito A. , Minami N.
Published: April 2003

A unique and systematic correlationhas been found between the hole mobility of oligosilane polycrystalline thin films and the length of the constituent molecules: the mobility increases with the silicon chain length in a zigzag fashion (odd–even effect—see Figure). Such strong correlation is shown to be brought about by the self‐organized structure of the films, wherein molecules form highly ordered multilayers extending to a macroscopic scale.
Process variables and their effects on grafting reactions of styrene and methyl methacrylate onto natural rubber
Authors: Arayapranee W. , Prasassarakich P. , Rempel G. L.
Published: April 2003

The graft copolymerization of styrene and methyl methacrylate onto natural rubber latex was studied under various reaction conditions using a cumene hydroperoxide redox initiator. The monomer conversion, graft copolymer compositions, and grafting efficiency were determined. The synthesized graft copolymers were purified and then characterized by proton nuclear magnetic resonance (1H‐NMR) analysis and differential scanning calorimetry (DSC). A 2 fractional factorial experimental design was applied to study the main effects on the grafting. The variables investigated in this work were the amount of the initiator and emulsifier, the presence or absence of a chain‐transfer agent, the styrene‐to‐methyl methacrylate ratio, the monomer‐to‐rubber ratio, and the reaction temperature. The measured response for the experimental design was the grafting efficiency. The analysis of the results from the design showed the sequence of the main effects on the observed response of the grafting of styrene and methyl methacrylate onto natural rubber, in ascending order. The amount of the chain‐transfer agent and the reaction temperature in the range of the test had significant effects and one marginally significant effect was the monomer‐to‐rubber ratio. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 63–74, 2003
Cytologic diagnosis of fibrous hamartoma of infancy: A case report
Authors: Mohanty Sambit K. , Dey Pranab
Published: April 2003

Fibrous hamartoma of infancy (FHI) is a rare benign lesion in the first 2 years of life with a distinctive histomorphologic appearance. There were only two descriptions of this entity in the cytology literature. In this article, the detailed clinical profile and cytologic features of a case of FHI is described in a 6‐month‐old male infant who presented with a nodular mass in the anterior axillary fold. Fine‐needle aspiration (FNA) cytology smears showed an admixture of adipose tissue fragments, discretely lying, and clusters of fibroblastic cells in association with myxoid and collagenous matrix. FNA cytology features along with proper clinical history, radiological findings, family history, and location of the lesion may be helpful to suggest the probable preoperative diagnosis of this lesion. Diagn. Cytopathol. 2003;28:272–273. © 2003 Wiley‐Liss, Inc.
One‐pot PTC synthesis of polyfused pyrazoles
Authors: El‐Saraf Gamal A. , El‐Sayed Ahmed M. , El‐Saghier Ahmed M. M.
Published: April 2003

Thienopyrazole 2, 3, 5, or 6 and thienopyrazolothiazepine 7, 9, and 11 derivatives were prepared via the reaction of the 3‐aminopyrazoline‐5‐one 1 with CS2 and different molar ratio of a variety of halo compounds having an active methylene under PTC conditions. Also, treatment of 1 with CS2 and alcoholic KOH in 2:1:1 molar ratio afforded dipyrazolopyridine derivatives 12 and 14. On other hand, the pyrazolothiadiazineone derivative 13 was obtained by treating compound 1 with CS2 and alcoholic KOH in 1:2:2 molar ratio. Under PTC conditions, compound 1, CS2, and ethyl cyanoacetate or malononitrile to gave the pyrazolopyridine derivatives 16 and 17. Coupling of compound 1 with diazonium acetates afforded the hydrazone derivatives 18a,b, which were oxidized with bromine to give pyrazolotriazoles 19a,b or cyclized with aldehydes to give pyrazolotriazine derivatives 20a–e. Bromination of compound 1 afforded monobromopyrazole derivative 21, which could be condensed to a dipyrazolopyrazindione 23. Finally, the dibromopyrazole derivative 22 was cyclized with 2‐mercaptoethanol or o‐phenylenediamine to give the spiropyrazoles 24a,b. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:211–217, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10129
Clinical spectrum of primary mediastinal tumors: A comparison of adult and pediatric populations at a single Japanese institution
Authors: Takeda Shin‐Ichi , Miyoshi Shinichiro , Akashi Akinori , Ohta Mitsunori , Minami Masato , Okumura Meinoshin , Masaoka Akira , Matsuda Hikaru
Published: April 2003

Background and Objectives

The purpose of this study was to review our Japanese institutional experience of mediastinal tumors and to compare differences in the clinical spectrum between adults and children.

Methods

We retrospectively reviewed the records of 806 patients (676 adults and 130 children) between 1951 and 2000 at our institution.

Results

There were 244 thymomas (36%), 106 germ cell tumors (16%), 95 congenital cysts (14%), 82 lymphomas (12%), 76 neurogenic tumors (11%), and 24 thyroid tumors (4%) in adult patients. There were 60 neurogenic tumors (46%), 24 germ cell tumor (19%), 17 lymphoma (13%), 10 congenital cysts (8%), and 5 thymomas (4%) in the pediatric patients. There was a significant higher incidence of neurogenic tumors and a lower incidence of thymomas and thyroid tumors in children than adults. The most common location was the anterior compartment (68%) in adults and the posterior compartment in children (52%). The prevalence of malignancy in pediatric patients was lower than adults (37% vs. 47%; P < 0.05). Symptoms due to compression or direct invasion into adjacent structures may have caused the higher incidence of dyspnea or respiratory distress in the pediatric group compared to the adults (15.4% vs. 4.0%; P < 0.001). There were fewer incidences of facial edema in children compared to adults (2.6% vs. 10.7%; P < 0.02). Emergent operations were required more often in the pediatric group than the adult group.

Conclusions

We demonstrated definite differences in histologic distribution, location, and symptomatology in mediastinal tumors between adult and pediatric populations, which should be considered in the evaluation and planning of a therapeutic modality for mediastinal tumors. J. Surg. Oncol. 2003;83:24–30. © 2003 Wiley‐Liss, Inc.
Korean medicinal plants inhibiting to Human Immunodeﬁciency Virus type 1 (HIV‐1) fusion
Authors: Chang Young‐Su , Woo Eun‐Rhan
Published: April 2003

In order to ﬁnd novel anti‐HIV agents from natural products, 80 MeOH extracts of Korean plants were applied to a syncytia formation inhibition assay, which is based on the interaction between the HIV‐1 envelope glycoprotein gp120/41 and the cellular membrane protein CD4 of T lymphocytes. The most potent HIV‐1 fusion inhibition was shown by the stem bark of Ailanthus altissima with 74.9 ± 4.4% at a concentration of 100 µg/mL. Copyright © 2003 John Wiley & Sons, Ltd.
Pharmacological and toxicological properties of Nigella sativa
Authors: Ali B. H. , Blunden Gerald
Published: April 2003

The seeds of Nigella sativa Linn. (Ranunculaceae), commonly known as black seed or black cumin, are used in folk (herbal) medicine all over the world for the treatment and prevention of a number of diseases and conditions that include asthma, diarrhoea and dyslipidaemia. This article reviews the main reports of the pharmacological and toxicological properties of N. sativa and its constituents.

The seeds contain both ﬁxed and essential oils, proteins, alkaloids and saponin. Much of the biological activity of the seeds has been shown to be due to thymoquinone, the major component of the essential oil, but which is also present in the ﬁxed oil.

The pharmacological actions of the crude extracts of the seeds (and some of its active constituents, e.g. volatile oil and thymoquinone) that have been reported include protection against nephrotoxicity and hepatotoxicity induced by either disease or chemicals. The seeds/oil have antiinflammatory, analgesic, antipyretic, antimicrobial and antineoplastic activity. The oil decreases blood pressure and increases respiration. Treatment of rats with the seed extract for up to 12 weeks has been reported to induce changes in the haemogram that include an increase in both the packed cell volume (PCV) and haemoglobin (Hb), and a decrease in plasma concentrations of cholesterol, triglycerides and glucose.

The seeds are characterized by a very low degree of toxicity. Two cases of contact dermatitis in two individuals have been reported following topical use. Administration of either the seed extract or its oil has been shown not to induce signiﬁcant adverse effects on liver or kidney functions.

It would appear that the beneﬁcial effects of the use of the seeds and thymoquinone might be related to their cytoprotective and antioxidant actions, and to their effect on some mediators of inﬂammation.Copyright © 2003 John Wiley & Sons, Ltd.
Prohibitin, an antiproliferative protein, is localized to mitochondria
Authors: Ikonen Elina , Fiedler Klaus , Parton Robert G. , Simons Kai
Published: April 2003

Prohibitin is a ubiquitously expressed protein with antiproliferative properties. When rat prohibitin tagged with a carboxy‐terminal c‐Myc epitope was expressed in baby hamster kidney cells the protein was targeted to mitochondria. In immunofluorescence microscopy prohibitin colocalized with a mitochondrial marker E3. Immunoelectron microscopy revealed that prohibitin was associated with the periphery of mitochondria. The amino‐terminus of prohibitin shares characteristics of the known mitochondrial import signals, and positioning of the tag at the N‐terminus causes accumulation of the protein in the cytoplasm. These findings help to direct functional studies on prohibitin and suggest that a mitochondrial protein may act as a tumor suppressor.
Substrate specificity of rat liver mitochondrial carnitine palmitoyl transferase I: evidence against α‐oxidation of phytanic acid in rat liver mitochondria
Authors: Singh Harmeet , Poulos Alfred
Published: April 2003

The two branched chain fatty acids pristanic acid (2,6,10,14‐tetramethylpentadecanoic acid) and phytanic acid (3,7,11,15‐tetramethylhexadecanoic acid) were converted to co‐enzyme A thioesters by rat liver mitochondrial outer membranes. However, these branched chain fatty acids could not be converted to pristanoyl and phytanoyl carnitines, respectively, by mitochondrial outer membranes. As expected, the unbranched long chain fatty acids, stearic acid and palmitic acid, were rapidly converted to stearoyl and palmitoyl carnitines, respectively, by mitochondrial outer membranes. These observations indicate that the branched chain fatty acids could not be transported into mitochondria. The data presented strongly suggest that in rat liver, α‐oxidation of phytanic acid occurs in organelles other than mitochondria.
Shape oscillations: a fundamental response of human neutrophils stimulated by chemotactic peptides?
Authors: Ehrengruber Markus U. , Coates Thomas D. , Deranleau David A.
Published: April 2003

Neutrophils undergo periodic cytoskeletal rearrangements that lead to cycles of shape change, ultimately resulting in cell translocation. Repeated stimulation of resting neutrophils with subsaturating chemoattractant doses induced transient sinusoidal oscillations in neutrophil filamentous actin content at the second and subsequent stimulations. Oscillation frequencies increased with increasing concentration of the first stimulus. In contrast, neutrophils pretreated with the phosphatidylinositol 3‐kinase inhibitor (17‐hydroxy)wortmannin displayed shape oscillations with the first stimulation, and the frequencies were independent of agonist type and dose. We demonstrate that oscillations in filamentous actin, which may be critical for neutrophil motility, can be induced in untreated cells by natural peptide chemoattractants.
Peroxynitrite‐mediated oxidative protein modifications
Authors: Ischiropoulos Harry , Al-Mehdi Abu B.
Published: April 2003

Proteins are targets of reactive species and detection of oxidatively modified proteins is often used as an index of oxidative stress. Peroxynitrite is a strong oxidant formed by reaction of nitric oxide with superoxide. Using fatty acid‐free bovine serum albumin as a model we examined peroxynitrite‐mediated protein modifications. The reaction of protein with peroxynitrite resulted in the oxidation of tryptophan and cysteine, in the nitration of tyrosine, in the formation of dityrosine, in the production of 2,4 dinitrophenylhydrazine‐reactive carbonyls and in protein fragmentation. The formation of 3‐nitrotyrosine represents a specific peroxynitrite‐mediated protein modification that is different from modifications mediated by reactive oxygen species.
Crystallisation and preliminary X‐ray analysis of the ‘common‐type’ acylphosphatase
Authors: Thunnissen Marjolein M.G.M. , Agango Elisha G. , Taddei Niccolò , Liguri Gianfranco , Cecchi Cristina , Pieri Alessandro , Ramponi Giampietro , Nordlund Pär
Published: April 2003

Single crystals of a ‘common‐type’ acylphosphatase from bovine testis have been grown. Crystals belong to space group C2 and have cell dimensions,,andβ= 104.8 and contain one monomer per asymmetric unit. The crystals diffract better than 2.0 Å resolution and are well suited for an X‐ray structure determination.
Interleukin 6 mediated differentiation and rescue of cell redox in PC 12 cells exposed to ionizing radiation
Authors: Abeyama Kazuhiro , Kawano Kazunori , Nakajima Toshihiro , Takasaki Ikuko , Kitajima Isao , Maruyama Ikuro
Published: April 2003

The differentiation of PC12 cells to a neuron‐like morphology was induced by ionizing radiation in the presence of serum. This effect was detectable at 5 grays (Gy) and reached a maximum at 10–20 Gy. Increases in the DNA binding activity of nuclear factor κB (NF‐κB) and increased Interleukin 6 (IL‐6) mRNA levels were observed at a dose of 15 Gy. Neutralization of supernatant IL‐6 by the addition of anti‐IL‐6 antibody inhibited the neuronal differentiation and decreased cellular redox. Ionizing radiation and serum may act synergistically as neurotropic factors.
Activin A‐induced apoptosis is suppressed by BCL‐2
Authors: Koseki Takeyoshi , Yamato Kenji , Krajewski Stanislaw , Reed John C. , Tsujimoto Yoshihide , Nishihara Tatsuji
Published: April 2003

Activin A, a member of TGFβ superfamily has various activities including induction of apoptosis in mammalian cells. However, it remains unknown how activin A induces cell death. To clarify this, we investigated the expression of BCL‐2 and BAX, and the effect of BCL‐2 overexpression on activin A‐induced apoptosis in B cell hybridoma cell lines. The activin A‐sensitive cell lines expressed BAX but not BCL‐2 and that activin A did not increase BAX levels. Overexpression of human BCL‐2 suppressed activin A‐induced apoptosis in these cells. Thus, activin A has been shown to induce apoptosis by a BCL‐2‐inhibitable mechanism without activating BAX.
New conformational properties induced by the replacement of Tyr‐64 in Desulfovibrio vulgaris Hildenborough ferricytochrome c553 using isotopic exchanges monitored by mass spectrometry
Authors: Guy Philippe , Jaquinod Michel , Rémigy Hervé , Andrieu Jean-Pierre , Gagnon Jean , Bersch Beate , Dolla Alain , Blanchard Laurence , Guerlesquin Françoise , Forest Eric
Published: April 2003

In order to study the conformational stability induced by the replacement of Tyr‐64 in Desulfovibrio vulgaris Hildenborough (DvH) cytochrome c
553, fast peptic digestion of deuterated protein followed by separation and measurement of related peptides using liquid chromatography coupled to electrospray ionization mass spectrometry was performed. We show that the H‐bonding and/or solvent accessibility properties were modified by the single‐site mutation. The mutant proteins can be classified into two groups: the Y64F and Y64L mutants with nearly unchanged deuterium incorporation compared to the wild‐type protein and the Y64S, Y64V and Y64A mutants with increased deuterium incorporation. The 70–74 peptide was the most affected by mutation of Tyr‐64, the phenylalanine mutant inducing slight stabilization whereas the serine mutant was significantly destabilized. In addition, from the analysis of the overlapping 37–57 and 38–57 peptides we can conclude that the amide proton of Tyr‐38 has been replaced by deuterium in all proteins.
The operations management role in hospital strategic planning
Authors: Butler Timothy W. , Leong G.Keong , Everett Linda N.
Published: April 2003

Although there is a wealth of research on operations management and strategic planning in hospitals, there has been little if any research on the integration of these two issues. Hospital administrators are being pressured to improve the quality of services and to curb costs ‐ two primary themes within the field of operations management. This leads us to wonder to what extent operations are considered within the strategic planning process and what impact it may have. By surveying the literature, we identify a pattern in hospital management research, and identify articles which address the operations capabilities of quality, flexibility, delivery and cost control. These articles can serve as a springboard for research in hospital operations strategy, an area that is largely neglected in the literature. We also provide examples of how hospitals are addressing operations capabilities, and conclude with implications for hospital administrators and a research agenda for researchers.
Workplace safety: A call for research
Authors: Brown Karen A.
Published: April 2003

The purpose of this paper is to call attention to the increased importance of workplace safety in the field of operations management, and to suggest ways in which this topic can be woven into research agendas. A key tenet is the proposition that the competitive priority construct (quality, cost, delivery and flexibility) may need to be expanded to include social responsibility ‐ with workplace safety as one dimension of this new priority. The cost of workplace injuries in the U.S. is increasing at an alarming rate, and accident occurrences have grown steadily over the last several years. The manufacturing sector is especially vulnerable to safety problems and, thus, is the central focus of this paper. A number of new factors are increasing the importance of related issues for operations managers. Three of these factors ‐ the quality movement, changes in technology and changes in operations practices ‐ are embedded within the operations function. Two others ‐ workforce diversity and organized labor interests ‐ are associated with the human resource function but have links with operations. Political, legal and public forces stem from outside the boundaries of the organization, but still have important influences on operations management. Regardless of the origins of these phenomena, all have direct effects on the management of operations and all have significant implications for research in this field.
Characterization of monoamine oxidase activity during early stages of quail embryogenesis
Authors: Pintar John E. , Maxwell Gerald D. , Breakefield Xandra O.
Published: April 2003

Catecholamines and other biogenic amines may play a role in early embryogenesis in addition to functioning as neurotransmitters after neuronal differentiation. Regulation of amine levels is mediated by several different parameters including activity levels of degradative enzymes. Since monoamine oxidase (EC 1.4.3.4) is the primary degradative enzyme for these biogenic amines, we have begun to characterize MAO activity during quail embryogenesis. Our results demonstrate that MAO activity is present at all stages of development examined (stages 2–22) and that the MAO specific activity levels are highest during the earliest stages (stages 2–6). Two types of MAO activity similar to adult avian and mammalian MAO‐A and MAO‐B have been demonstrated by differential clorgyline sensitivity of tryptamine deamination. In addition, SDS‐PAGE of embryonic quail [3H]pargyiine‐labeled MAO demonstrates that the quail MAO‐A and MAO‐B flavin‐containing subunits have apparent molecular weights of 63,000 and 62,000 respectively.

We have begun to assess the functional significance of embryonic quail MAO activity by daily injection of MAO inhibitors (clorgyline or clorgyline plus deprenyl) into fertilized eggs. Clorgyline injection selectively and completely inhibited MAO‐A activity, while injection of clorgyline and deprenyl inhibited both MAO‐A and MAO‐B activities when embryos were assayed after either 2 or 7 days of embryonic development. This paradigm will allow a detailed examination of the effects of MAO inhibition on the developing embryo.