bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics of nonlinearly coupled upper-hybrid waves and modified Alfvén modes in a magnetized dusty plasma
Authors: Shukla P. K. , Stenflo L.
Published: October 2003

The nonlinear interaction between a large amplitude electrostatic upper-hybrid (uh) wave and Rao’s modified Alfvén mode in a uniform dusty magnetoplasma is considered. The wave equation for the uh wave envelope in a background of electron density and compressional magnetic field perturbations due to the Alfvén mode is presented, and an equation for the latter in the presence of the uh wave ponderomotive force is derived. A nonlinearly coupled uh wave and driven Rao’s modified Alfvén mode equations are then used to investigate the parametric instabilities of a constant amplitude uh pump wave, and the formation of spiky uh wave solitons. The relevance of our investigation to space plasmas is discussed.
Evolution of Davidson–Cole relaxation behavior in random conductor–insulator composites
Authors: Calame J. P.
Published: October 2003

The evolution of the frequency-dependent, complex dielectric permittivity of three-dimensional, random conductor–insulator composites as a function of conductive inclusion concentration is explored by numerical simulation. A smooth transition from Debye behavior at low inclusion concentrations to a non-Debye, Davidson–Cole relaxation structure at higher concentrations is typically observed below the percolation threshold. The prevalence of the Davidson–Cole behavior and variations in relaxation parameters with respect to clustering statistics are explored through a survey of random networks. The dielectric response in denser composites is also explored, in both a standard randomly filled, percolating configuration and in a different type of random filling in which percolation has been deliberately prevented. In both cases, the relaxation component continues to exhibit a Davidson–Cole functional form. The passage through percolation does not strongly affect the Davidson–Cole exponent in the standard filling case, but in the percolation-prevention case a strong increase in exponent with inclusion concentration is observed.
Radiation-induced junction formation behavior of boron-doped Czochralski and float zone silicon crystals under 3 MeV proton irradiation
Authors: Chun M. D. , Kim D. , Huh J. Y.
Published: October 2003

A comparative study was performed on the junction formation behavior of boron-doped p-type Czochralski (Cz) and float zone (Fz) Si wafers, which differed mainly in interstitial oxygen concentration, upon 3 MeV proton irradiation with fluences of up to 2×1015 cm−2. The region around the projected range in both the Cz and Fz Si wafers converted its conduction type to n type at fluences between 1×1013 and 3×1013 cm−2, which is most probably due to the formation of hydrogen-related donors. The main difference between the Cz and Fz Si wafers was in the susceptibility of the proton track region to type conversion. The proton track region of the Cz Si wafer converted to n type at fluence between 1×1013 and 3×1013 cm−2, whereas that of the Fz Si wafer showed only an increase in resistivity without any type conversion as the fluence increased up to 2×1015 cm−2, which was attributed to oxygen-related donor formation in the case of the Cz Si wafer. The present results are discussed with respect to the radiation-induced failure mechanisms of n+/p/p+-structured Si space solar cells based on boron-doped Cz and Fz Si.
Substrate effects on the ferroelectric properties of fine-grained BaTiO3 films
Authors: Ring Ken M. , Kavanagh Karen L.
Published: October 2003

The development of ferroelectric properties in barium titanate (BaTiO3) polycrystalline films has been investigated as a function of substrate type. The films were deposited by physical vapor deposition (PVD) onto different, Pt-coated substrates (magnesium oxide, thermally oxidized silicon, and sapphire) and annealed at temperatures from 725 to 1050 °C. Grain sizes from 50 to 200 nm were produced, with structural and dielectric properties that showed a marked transition from nonferroelectric to ferroelectric behavior across this range. Anneal temperatures below 950 °C result in films with grain sizes less than 150 nm, and ferroelectric properties that are strongly suppressed, regardless of the substrate. Observations for this temperature range include low dielectric constant (ε), no polarization hysteresis, and no peaks in the temperature dependence of the dielectric constant. The onset of ferroelectric behavior occurs for anneal temperatures above 950 °C, coinciding with the appearance of strong substrate effects on the dielectric properties. Such BaTiO3 films on Pt/MgO show the largest dielectric constant, remnant polarization, and temperature dependence of ε, while films on Pt/sapphire exhibit the weakest of each of these properties. Films on Pt/barrier/Si exhibit dielectric properties with values in between that of films on Pt/MgO and Pt/sapphire. The dependence of BaTiO3 ferroelectric properties on the substrate is related to a combination of the BaTiO3 grain and size orientation, determined partly by the underlying Pt surface, and to the thermal expansion properties of the substrate. However, these factors only influence the BaTiO3 dielectric properties for those films that exhibit ferroelectric properties. In this way, the anneal temperature and substrate dependence of the films are linked.
Competition between photodetachment and photodissociation in O2−
Authors: Dinu Laura , Groenenboom Gerrit C. , van der Zande Wim J.
Published: October 2003

Using fast beam photofragment spectroscopy, we have studied the competition between photodissociation and photodetachment in O2−. The photodissociation fraction is ∼10% and increases somewhat between 285 and 266 nm. High resolution photofragment spectroscopy shows that the O2− beam is composed of v=0 ions only. The photofragment angular distribution has an anisotropy parameter β=1.9, indicating that the process of dissociation has a parallel character, attributed to the A 2Πu←X 2Πg transition. A detailed analysis of the kinetic energy release of the photofragments shows the structure related to the distribution over the six fine-structure dissociation limits O− (2P3/2,1/2)+O (3P2,1,0). The results are compared with an analytical diabatic dissociation model, taking into account the long range charge–quadrupole interactions; the A 2Πu is described in a Born–Oppenheimer electrostatic aproximation and projected onto the different fine-structure states at large internuclear separation using analytical expressions derived from the long range charge–quadrupole interactions between O− and O fragments.
Study on Er3+ emission from the erbium-doped hydrogenated amorphous silicon suboxide film
Authors: Chen C. Y. , Chen W. D. , Song S. F. , Xu Z. J. , Liao X. B. , Li G. H. , Ding K.
Published: October 2003

The erbium-doped hydrogenated amorphous silicon suboxide films containing amorphous silicon clusters were prepared. The samples exhibited photoluminescence peaks at around 750 nm and 1.54 μm, which could be assigned to the electron-hole recombination in amorphous silicon clusters and the intra-4f transition in Er3+, respectively. Correlations between the intensities of these two photoluminescence peaks and oxidation and dehydrogenation of the films during annealing were studied. It was found that the oxidation is triggered by dehydrogenation of the films even at low annealing temperatures, which decisively changes the intensities of the two photoluminescence peaks. On the other hand, the increase of Er content in the erbium-doped hydrogenated amorphous silicon suboxide film will enhance Er3+ emission at 1.54 μm, while quench amorphous silicon cluster emission at 750 nm, such a competitive relationship, was also observed in the erbium-doped silicon nanocrystals embedded in SiO2 matrix. Moreover, we found that Er3+ emission is not sensitive to whether silicon clusters are crystalline or amorphous. The amorphous silicon clusters can be as sensitizer on Er3+ emission as that of silicon nanocrystals.
Point defects in thermal SiO2 layers: Thermally stimulated luminescence and corona oxide electrical characterization
Authors: Vedda A. , Bonelli A. , Martini M. , Rosetta E. , Spinolo G. , Vitali M. E. , Alessandri M.
Published: October 2003

Point defects in thin (≈100 Å) SiO2 layers thermally grown on silicon were investigated by thermally stimulated luminescence (TSL) and corona oxide characterization of semiconductor measurements. A comparison is proposed between layers grown by steam and N2 diluted steam processes. The effects of post-growth annealing treatments in N2O, NO, and N2 atmospheres and of ion irradiation (As or P) have been investigated. A good correlation between the results obtained by the two different techniques has been found, suggesting a common structural origin of defects responsible for TSL active traps and total oxide charge.
Enhanced optical and electrical properties of layer-by-layer luminescent films
Authors: Marletta A. , Piovesan E. , Dantas N. O. , de Souza N. C. , Olivati C. A. , Balogh D. T. , Faria R. M. , Oliveira O. N.
Published: October 2003

The electrical and optical properties of luminescent films from poly(p-phenylene vinylene) (PPV) and poly(o-methoxyaniline) (POMA) produced via the layer-by-layer technique are reported. POMA layers were obtained in a nonself-limiting process from its emeraldine salt. PPV was thermally converted from the precursor poly(xylylidene tetrahydrothiophenium chloride) with sodium dodecylbenzenesulfonate (DBS) at low temperatures of ∼110 °C and short times (∼30 min). The line shape of absorbance and photoluminescence (PL) is not affected with the PPV conversion reaction. High thermal stability of PPV was observed, with the integrated PL decreasing only 10% when the temperature was increased from 10 to 300 K. This decrease was accompanied by a small blue shift of 5 nm in the zero-phonon peak and a low electron–phonon coupling with a Huang–Rhys factor S<1 in the vibration spectral region. The combination of POMA and indium–tin–oxide (ITO) as transparent electrode and PPV+DBS as active layer (ITO/POMA/PPV+DBS/Al) leads to a decrease of 70% in the operating voltage compared with the conventional polymer light emitting-diode ITO/PPV/Al, which means that the POMA layer plays a protective role for the ITO electrode. Furthermore, the POMA layer has its electrical characteristics preserved at high temperatures, with the assistance of a codoping process from acid diffusion from the PPV/DBS layers.
Reflectance difference spectroscopy of gallium phosphide(001) surfaces
Authors: Law D. C. , Sun Y. , Hicks R. F.
Published: October 2003

Gallium phosphide(001) surfaces have been prepared by metalorganic vapor-phase epitaxy, and characterized in situ by low-energy electron diffraction, x-ray photoemission spectroscopy, and reflectance difference spectroscopy. Three stable phases were observed: (2×1), (1×1), and (2×4) with phosphorus coverages of 1.00, 0.67, and 0.13 ML, respectively. Reflectance difference spectra obtained at coverages intermediate between these three values were found to be linear combinations of the spectra of the pure phases. In particular, ΔR/R(mixed)=mΔR/R(1×1)+(1−m)ΔR/R(2×1) or (2×4), where m is a weighting factor. The weighting factors were used to estimate the phosphorus coverage, and these results agreed to within 5.0% of the values measured by x-ray photoelectron spectroscopy.
Experimental study and modeling of the influence of screw dislocations on the performance of Au/n-GaN Schottky diodes
Authors: Huang Y. , Chen X. D. , Fung S. , Beling C. D. , Ling C. C.
Published: October 2003

Current–voltage (I–V) characteristics of macroscopic Schottky diodes fabricated on different GaN templates grown by metalogranic chemical vapor deposition on sapphire substrates were investigated. The number of dislocations under the Au Schottky contact was determined by atomic force microscopy combined with hot H3PO4 etching and the screw dislocations in the GaN films were found to have a strong influence on the reverse leakage current of the Au/n-GaN Schottky diodes. The leakage current is increased when high-density screw dislocations exist under the Au Schottky contact. A model based upon the presence of dislocations at the Au/GaN interface has been used to explain this behavior. It has been proposed that these dislocations result in the lowering of the barrier height in the localized regions, and thus significantly affect the reverse I–V characteristics of the Schottky diodes.
Ion-channeling analysis of As relocation in heavily doped Si:As irradiated with high-energy ions
Authors: Lulli G. , Albertazzi E. , Bianconi M. , Ferri M.
Published: October 2003

Silicon on insulator layers doped with 8×1020 As cm−3 and thermally equilibrated at 1100 °C, have been irradiated with 2 MeV Si+ ions. Rutherford backscattering–channeling analysis shows an increase in As disorder upon irradiation significantly larger than the increase in Si disorder, while electrical measurements show a large decrease in electrical activation. Monte Carlo simulation of channeling angular scans suggests that the enhanced As disorder effect is due to the preferential relocation of dopant atoms slightly displaced from lattice sites, which appear the main reason responsible for the electrical deactivation in the unirradiated sample and are believed to be in the form of As–vacancy clusters. Upon 600 °C 15 s annealing, the As atoms randomly relocated by ion irradiation almost completely recover their original configuration, probably capturing vacancies and forming, again, the complexes dissociated by ion irradiation.
Growth of high-k silicon oxynitride thin films by means of a pulsed laser deposition-atomic nitrogen plasma source hybrid system for gate dielectric applications
Authors: Desbiens E. , El Khakani M. A.
Published: October 2003

High-k silicon oxynitride (SiOxNy) thin films have been successfully grown by means of a hybrid deposition process based on the combination of the pulsed laser deposition (PLD) plume of silicon species in an oxygen background together with a remote plasma-based atomic nitrogen source (ANS). This pulsed laser deposition-atomic nitrogen source (PLD-ANS) hybrid method is found to be highly effective for further nitrogen incorporation into SiOxNy films. At a laser intensity of 2.5×108 W/cm2 and a deposition temperature (Td) of 300 °C, it was shown that the N content of the SiOxNy films could be controlled over a concentration range as wide as 0–35 at. %, by controlling the partial pressure ratio of N to O2 in the deposition chamber. The structural and dielectric properties of the PLD-ANS SiOxNy films were systematically investigated as a function of their N content. Microstructural analyses revealed that the increasing incorporation of N into the SiOxNy films occurs through the formation of Si–N bonds to the detriment of Si–O ones. Both the dielectric constant (k) and the breakdown field of the SiOxNy thin films are found to increase significantly with N content. At the highest N content (35 at. %), the PLD-ANS films exhibit a high k-value of about 9.5 and a breakdown field as high as 19 MV/cm. It appears that Poole–Frenkel emission with compensation is the most predominant conduction mechanism in the SiOxNy films. By enabling control of the N content during deposition, the PLD-ANS approach provides the means to achieve desirable N profile engineering in the SiOxNy dielectric thin films.
Strong electro-optic effect in electrically poled photoaddressable polymers
Authors: Bertram Ralph P. , Soergel Elisabeth , Blank Holger , Benter Nils , Buse Karsten , Hagen Rainer , Kostromine Serguei G.
Published: October 2003

Electrically poled photoaddressable polymers, originally designed for optical data storage, are investigated in an interferometric setup. After optimization of the corona poling conditions, we obtain Pockels coefficients r33 of 44 pm/V at 1555 nm. Even at nonoptimum temperatures, the material can be electrically poled quite efficiently using light to trigger trans–cis isomerization cycles. At room temperature, the degree of poling is stable over months. At elevated temperatures, after a fast initial decay, again stable or very slowly decaying electro-optic coefficients are observed.
Monte Carlo method for modeling of small signal response including the Pauli exclusion principle
Authors: Smirnov S. , Kosina H. , Nedjalkov M. , Selberherr S.
Published: October 2003

A Monte Carlo method for small signal analysis of degenerate semiconductors is presented. The response to an electric field impulse parallel to the stationary electric field is obtained using the nonlinear Boltzmann kinetic equation with the Pauli exclusion principle in the scattering operator. After linearization of the Boltzmann equation a new Monte Carlo algorithm for small signal analysis of the nonlinear Boltzmann kinetic equation is constructed using an integral representation of the first order equation. The generation of initial distributions for two carrier ensembles which arise in the method is performed by simulating a main trajectory to solve the zero order equation. The normalization of the static distribution function is discussed. To clarify the physical interpretation of our algorithm we consider the limiting case of vanishing electric field and show that in this case kinetic processes are determined by a linear combination of forward and backward scattering rates. It is shown that at high degeneracy backward scattering processes are dominant, while forward transitions are quantum mechanically forbidden under such conditions due to the Pauli exclusion principle. Finally, the small signal Monte Carlo algorithm is formulated and the results obtained for degenerate semiconductors are discussed.
Influence of self-affine surface roughness on the friction coefficient for rubbers
Authors: Palasantzas George
Published: October 2003

For a viscous rubber sliding onto a self-affine rough surface, the friction coefficient increases monotonically with decreasing roughness exponent H and at a rapid rate for H<0.5. This is because the surface becomes rougher (with decreasing H) at short roughness wavelengths (<ξ) leading therefore to increased friction. Similar is also the behavior with decreasing the in-plane roughness correlation length ξ (for fixed roughness amplitude w). Nevertheless, the roughness exponent H appears to influence more the friction coefficient than the in-plane correlation length ξ. For relatively low sliding speeds, analytic calculations of the coefficient friction were also feasible for the limiting roughness exponents H=0 and H=1. Finally, under conditions of incomplete contact the friction coefficient was shown to decrease below its value of complete contact for contact lengths λcon<ξ and relatively high sliding velocities.
Mean-time-to-failure study of flip chip solder joints on Cu/Ni(V)/Al thin-film under-bump-metallization
Authors: Choi W. J. , Yeh E. C. C. , Tu K. N.
Published: October 2003

Electromigration of eutectic SnPb flip chip solder joints and their mean-time-to-failure (MTTF) have been studied in the temperature range of 100 to 140 °C with current densities of 1.9 to 2.75×104 A/cm2. In these joints, the under-bump-metallization (UBM) on the chip side is a multilayer thin film of Al/Ni(V)/Cu, and the metallic bond-pad on the substrate side is a very thick, electroless Ni layer covered with 30 nm of Au. When stressed at the higher current densities, the MTTF was found to decrease much faster than what is expected from the published Black’s equation. The failure occurred by interfacial void propagation at the cathode side, and it is due to current crowding near the contact interface between the solder bump and the thin-film UBM. The current crowding is confirmed by a simulation of current distribution in the solder joint. Besides the interfacial void formation, the intermetallic compounds formed on the UBM as well as the Ni(V) film in the UBM have been found to dissolve completely into the solder bump during electromigration. Therefore, the electromigation failure is a combination of the interfacial void formation and the loss of UBM. Similar findings in eutectic SnAgCu flip chip solder joints have also been obtained and compared.
Negative Barkhausen jumps in amorphous ribbons of Fe63B14Si8Ni15
Authors: Zani Maurizio , Puppin Ezio
Published: October 2003

Negative Barkhausen jumps in amorphous ribbons of Fe63B14Si8Ni15 have been investigated both with the traditional inductive coil, which probes a large sample region, and also with a space resolved magneto-optical Kerr ellipsometer. After these negative jumps the magnetization vector is antiparallel with respect to the external field in the sample region where the reversal took place. Magneto-optical data indicate that negative jumps take place only in selected regions of the sample. The amplitude ΔM of both positive and negative jumps follows a power-law probability distribution: P(ΔM)=ΔM−α. The observed values of the critical exponent α are very similar, within the experimental error, both for positive and negative jumps (α=1.6).
Admittance spectroscopy revisited: Single defect admittance and displacement current
Authors: Karpov V. G. , Shvydka Diana , Jayamaha U. , Compaan A. D.
Published: October 2003

A general approach to semiconductor device admittance spectroscopy analysis is developed, which describes arbitrary defect distributions, and gives the geometrical capacitance limit and the relationship between the measured conductance and capacitance. A single defect capacitance concept is introduced that facilitates the analysis. Special attention is paid to accounting for the role of displacement current, which was overlooked in the preceding work. An experimental verification of the approach is given.
Sensitized thulium blue upconversion emission in Nd3+/Tm3+/Yb3+ triply doped lead and cadmium germanate glass excited around 800 nm
Authors: Gouveia-Neto A. S. , da Costa E. B. , dos Santos P. V. , Bueno L. A. , Ribeiro S. J. L.
Published: October 2003

Bright blue upconversion emission by thulium ions in PbGeO3–PbF2–CdF2 glass triply doped with Nd3+–Tm3+–Yb3+ under diode laser excitation around 800 nm is reported. The results revealed that the Nd3+/Tm3+/Yb3+-codoped sample generated ten times more 475 nm blue upconversion fluorescence than the Yb3+-sensitized Tm3+-doped one, under the same excitation power. The upconversion process also showed a strong dependence upon the Yb3+ concentration. The results also indicated that the neodymium ions played a major role in the upconversion process by transfering the 800 nm excitation to thulium ions. The population of the Tm3+ ions G41 emitting level was accomplished through a multiion interaction involving ground-state absorption of pump photons around 800 nm by the Nd3+(4I9/2→2H9/2, 4F5/2) and Tm3+(3H6→3F4) ions followed by energy-transfer processes involving the Nd3+–Yb3+(4F3/2, 2F7/2→4I11/2, 2F5/2) and Yb3+–Tm3+(2F5/2, 3F4→2F7/2, 1G4) pairs.
Films of silicon nanoparticles grown by gas aggregation
Authors: Scheier P. , Marsen B. , Sattler K.
Published: October 2003

The growth of nanometer-sized spherical particles was observed after condensation of pure silicon vapor on a clean graphite surface. Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy were performed on these silicon nanoparticles. The particles are arranged densely packed in perfectly flat layers and exhibit a very narrow size distribution. The tunneling current plotted versus the voltage between the STM tip and the sample (I–V curves) suggests an energy gap of these films of silicon particles of several eV. However, no ultraviolet photoluminescence could be observed in the visible. The particles can be swept from the surface by the scanning tip without reduction of the resolution of the STM. Thus, the coupling of the particles to the graphite can be expected to be weak.
Quantum-dot optical temperature probes
Authors: Walker Glen W. , Sundar Vikram C. , Rudzinski Christina M. , Wun Aetna W. , Bawendi Moungi G. , Nocera Daniel G.
Published: October 2003

The steady-state photoluminescence (PL) properties of cadmium selenide quantum dots (QDs) with a zinc sulfide overlayer [(CdSe)ZnS] can be strongly dependent on temperature in the range from 100 to 315 K. The PL intensity from 50 to 55 Å (CdSe)ZnS QDs in poly(lauryl methacrylate) matrices increases by a factor of ∼5 when the temperature is decreased from 315 to 100 K, and the peak of the emission band is blueshifted by 20 nm over the same range. The change in PL intensity is appreciable, linear, and reversible (−1.3% per °C) for temperatures close to ambient conditions. These properties of (CdSe)ZnS dots are retained in a variety of matrices including polymer and sol–gel films, and they are independent of excitation wavelength above the band gap. The significant temperature dependence of the luminescence combined with its insensitivity to oxygen quenching establishes (CdSe)ZnS dots as optical temperature indicators for temperature-sensitive coatings.
Influence of vibrational excitation on the reaction Li(2 2PJ)+H2(v=1)→LiH(X 1Σ+)+H
Authors: Chen Jye-Jong , Lin King-Chuen
Published: October 2003

The reaction Li(2 2PJ)+H2(v=1)→LiH(X 1Σ+)+H is studied to understand the effect of vibrational excitation on the reaction pathways. The hydrogen molecules in the v=1, j=0–3 levels are populated by using stimulated Raman pumping (SRP). A pump–probe technique is employed simultaneously to initiate the reaction and monitor the products. The pump–SRP and SRP–probe delay time are short enough to allow for the products to be in a nascent state. The population fraction in the v=1 level can be estimated to be 7.5% by using coherent anti-Stokes Raman spectroscopy. As characterized by Boltzmann rotational temperature of 730 K, the rotational state distributions of LiH(v=0) obtained with H2(v=1) appear to be unimodal, similar to those obtained with H2(v=0), but the product yield is enhanced by a factor of 7–8 times. According to the potential energy surfaces calculations, the insertion mechanism in (near) C2v collision configuration is favored. The Li(2 2PJ)–H2 collision is initially along the 2A′ surface in the entrance channel and then transits to the ground 1A′ surface, from which the products are formed. When H2 stretches to its outer turning point (∼0.9 Å), the 2A′ surface may diabatically couple to the 1A′ surface in the attractive region. An energy barrier of 4300 cm−1 will otherwise obscure the reaction if the H2 bond distance is fixed at 0.75 Å. The energy deposited in the v=1 level simply enlarges the H2 bond distance to help facilitate the reaction and increase the subsequent product yield. The lack of detection of the product LiH(v⩾1) implies that the exoergic energy by 2530 cm−1 should not be distributed statistically among different freedom of motions. The vibrational excitation does not seem to open up an additional pathway for the reaction.
Simulation of small-scale coronal explosives due to magnetic reconnections
Authors: Fan Quan-Lin , Feng Xue-Shang , Xiang Chang-Qing , Zhong Ding-Kun
Published: October 2003

The dynamics of small-scale explosive phenomena in the lower corona have been simulated by solving the compressible magnetohydrodynamic equations. Numerical results show that the magnetic reconnections in a long coronal current sheet consist of a series of discrete small reconnection events, coalescence of magnetic islands, and plasmoid ejections, corresponding to the explosive events occurring intermittently and as bursts in a mentioned observational case. The generation of magnetic islands via multiple-X-point reconnection and their coalescence processes, to some extent, are qualitatively similar to the sequence of brightenings in the active region NOAA 8668. The strong ejections are possibly related to the recorded extreme ultraviolet (EUV) emitting structures. Morphological comparison and quantitative check of the plasma parameters support this candidate mechanism, and the idea that explosive events that appear to last long may not be single events, but a succession of explosive events either resolved or unresolved. The temporal energy conversion process is also examined.
Tuning the properties of magnetic CdMnTe quantum dots
Authors: Mackowski S. , Jackson H. E. , Smith L. M. , Kossut J. , Karczewski G. , Heiss W.
Published: October 2003

We show that CdMnTe self-assembled quantum dots (QDs) can be formed by depositing a submonolayer of Mn ions over a ZnTe surface prior to deposition of the CdTe dot layer. Single-dot emission lines and strongly polarized QD photoluminescence (PL) in an applied magnetic field confirm the presence of Mn in individual QDs. The width of PL lines of the single CdMnTe dots is 3 meV due to magnetic moment fluctuations (MMFs) of the Mn ions. After rapid thermal annealing, the emission lines of individual magnetic QDs narrow significantly to 0.25 meV, showing that effect of MMFs is strongly reduced, most probably due to an increase in the average QD size. These results suggest a way to tune the spin properties of magnetic QDs.
Perceived Threat and Authoritarianism
Authors: Feldman Stanley , Stenner Karen
Published: October 2003

There has been a long history of work on authoritarianism that has looked at the role of societal threat. Much of the empirical research in this tradition has relied on aggregate data to examine the relationship between societal threat and authoritarian attitudes and behaviors. Our analysis uses individual‐level data and a range of perceived threat measures to better understand the dynamics of authoritarianism and threat. We also move beyond the hypothesis of a direct relationship between threat and authoritarianism, and hypothesize instead that the relationship involves interaction effects: societal threat activates authoritarian predispositions. As predicted, our analysis finds no evidence of a direct effect of societal threat but significant evidence of an interaction between authoritarian predispositions and perceived threat. We consider the implications of these results for our understanding of authoritarianism.
Young Muslim Women in France: Cultural and Psychological Adjustments
Authors: De Wenden Catherine Wihtol
Published: October 2003

Even though France has experienced increasing and inevitable feminization in its immigrant population since 1974, research has tended to ignore the role of immigrant women, especially Muslim women, in the migration process. Public attention has been diverted by concern over such relatively marginal issues as the headscarf affair, and insufficient attention has been paid to the important role Muslim women play in France, especially those coming from Algeria. These women function as cultural mediators between the traditional culture of the sending country and the modern one of the host country. They see themselves as both tradition‐bearers and integration proponents. The demands of immigration have given rise to the growth and development of different leaders, among them cultural mediators seeking a bridge between Islam and modernity, economic mediators seeking to establish women in the media and as entrepreneurs, and political mediators who seek access to power at the local level for the immigrants. These new mediators will eventually shape a new generation of female actors very far from the traditional countries of origin, although for the time being they still suffer from the inequality of rights for women and chances in their overall social life.
“Moralism” and the Gender Gap: Judgments of Political Ethics in Japan
Authors: Pharr Susan J.
Published: October 2003

This article investigates whether women are, as many claim, “moralists”—that is, moral and ethical standard‐setters who seek clean politics and have strict standards for public officials. An analysis of data from the 1996 Japanese Elections and Democracy Study survey and from 18 focus groups conducted in 1996 indicates that women in Japan are not moralists. As elsewhere, there is a gender gap in Japan on “issue preference sets,” with women favoring a “care” agenda, but women assign political ethics less importance than do men, even though women are more likely to see adverse effects from political corruption. Studying people's judgments of four ethics scenarios reveals minimal gender gaps; controlling for education and age, women's judgments overall are less, not more, strict than men's. Among women, age is a better predictor of moralism than education; older women are stricter than younger women on political ethics. This is attributed to gender‐based differences in moral reasoning: Japanese women and men both rely heavily on a “relation‐based” frame (which is situation‐specific and requires extensive social information), but gender stratification patterns create information inequalities. Younger women lack social information necessary for judging political misconduct, whereas older women overcome the information deficit through life experience.
Bioethics, Theology, and Social Change
Authors: Cahill Lisa Sowle
Published: October 2003

Recent years have witnessed a concern among theological bioethicists that secular debate has grown increasingly “thin,” and that “thick” religious traditions and their spokespersons have been correspondingly excluded. This essay disputes that analysis. First, religious and theological voices compete for public attention and effectiveness with the equally “thick” cultural traditions of modern science and market capitalism. The distinctive contribution of religion should be to emphasize social justice in access to the benefits of health care, challenging the for‐profit global marketing of research and biotechnology to wealthy consumers. Second, religion and theology have been and are still socially effective in sponsoring activism for practical change, both locally and globally. This claim will be supported with specific examples; with familiar concepts like subsidiarity and “middle axioms”; and with recent analyses of “participatory democracy” and of emerging, decentralized forms of global governance.
Self‐Deception and Responsibility for Addiction
Authors: Levy Neil
Published: October 2003

ABSTRACT We frequently accuse heavy drinkers and drug users of self‐deception if they refuse to admit that they are addicted. However, given the ways in which we usually conceptualize it, acknowledging addiction merely involves swapping one form of self‐deception for another. We ask addicts to see themselves as in the grip of an irresistible desire, and to accept that addiction is an essentially physiological process. To the extent this is so, we, as much as the addicts, suffer from self‐deception, and the responsibility for their state is in part ours. Conversely, since addicts are compelled to accept a self‐deceptive image of themselves, they are at least partially excused from blame for their self‐deception.
Can it Ever Be Better Never to Have Existed At All? Person‐Based Consequentialism and a New Repugnant Conclusion
Authors: Roberts Melinda A.
Published: October 2003

ABSTRACT Broome and others have argued that it makes no sense, or at least that it cannot be true, to say that it is better for a given person that he or she exist than not. That argument can be understood to suggest that, likewise, it makes no sense, or at least that it cannot be true, to say that it is worse for a given person that he or she exist than that he or she never have existed at all.

This argument is of critical importance to the question of whether consequentialist theory should take a traditional, aggregative form or a less conventional, person‐affecting, or person‐based, form. I believe that, potentially, the argument represents a far more serious threat to the person‐based approach than does, for example, Parfit's two medical programmes example. Parfit's example nicely illustrates the distinction between aggregative and person‐based approaches and raises important questions. But the example — though not, I think, by Parfit — is sometimes pressed into service as a full‐fledged counterexample against the person‐based approach. As such, I argue, the example is not persuasive. In contrast, the Broomeian argument, if correct, is definitive. For that argument relies on certain metaphysical assumptions and various uncontroversial normative claims — and hence nicely avoids putting into play the controversial normative claims that lie at the very heart of the debate.

The purpose of the present paper, then, is to evaluate the Broomeian argument. I argue that this potentially definitive challenge to a person‐based approach does not in fact succeed.
Scheduling the production of rolling ingots: industrial context, model, and solution method
Authors: Schwindt C. , Trautmann N.
Published: October 2003

We study a real‐world scheduling problem arising in the context of a rolling ingots production. First we review the production process and discuss peculiarities that have to be observed when scheduling a given set of production orders on the production facilities. We then show how to model this scheduling problem using prescribed time lags between operations, different kinds of resources, and sequence‐dependent changeovers. A branch‐and‐bound solution procedure is presented in the second part. The basic principle is to relax the resource constraints by assuming infinite resource availability. Resulting resource conflicts are then stepwise resolved by introducing precedence relationships among operations competing for the same resources. The algorithm has been implemented as a beam search heuristic enumerating alternative sets of precedence relationships.
A genetic algorithm and the Monte Carlo method for stochastic job‐shop scheduling
Authors: Yoshitomi Y. , Yamaguchi R.
Published: October 2003

This paper proposes a method for solving stochastic job‐shop scheduling problems using a hybrid of a genetic algorithm in uncertain environments and the Monte Carlo method. First, the genetic algorithm in uncertain environments is applied to stochastic job‐shop scheduling problems where the processing times are treated as stochastic variables. The Roulette strategy is adopted for selecting the optimum solution having the minimum expected value for makespan. Applying crossover based on Giffler and Thompson's algorithm results in two offspring inheriting the ancestor's characteristics as the operation completion times averaged up to the parent's generation. Individuals having very high frequency through all generations are selected as the good solutions. Second, the Monte Carlo method is effectively used for finding out the approximately optimum solution among these good solutions.
Word Searches in NNS–NS Interaction: Opportunities for Language Learning?
Authors: Brouwer Catherine E.
Published: October 2003

A substantial portion of second language acquisition research focuses on interactional practices in which nonnative speakers (NNSs) engage. From various theoretical viewpoints, it is assumed that certain types of interactional practices, specifically those in which participants focus on linguistic form, may promote language learning. The question of whether, and under which conditions, such sequences can be seen as providing the NNS with language learning opportunities, is considered in a purely data‐driven way, applying conversation analysis (CA) as a method. The article considers one specific type of interactional practice, “word search” sequences, and opportunities for language learning that they may provide for NNSs on the basis of naturally occurring interactions between native speakers of Danish and Dutch speakers of Danish. It is argued that in order to distinguish between “language learning opportunities” and other types of interactional practices, the researcher needs to analyze the data in detail.
Air Pollution and Climate-Forcing Impacts of a Global Hydrogen Economy
Authors: Schultz Martin G. , Diehl Thomas , Brasseur Guy P. , Zittel Werner
Published: October 2003

If today's surface traffic fleet were powered entirely by hydrogen fuel cell technology, anthropogenic emissions of the ozone precursors nitrogen oxide (NO
x
) and carbon monoxide could be reduced by up to 50%, leading to significant improvements in air quality throughout the Northern Hemisphere. Model simulations of such a scenario predict a decrease in global OH and an increased lifetime of methane, caused primarily by the reduction of the NO
x
emissions. The sign of the change in climate forcing caused by carbon dioxide and methane depends on the technology used to generate the molecular hydrogen. A possible rise in atmospheric hydrogen concentrations is unlikely to cause significant perturbations of the climate system.
Molecular Imaging: Looking at Problems, Seeing Solutions
Authors: Herschman Harvey R.
Published: October 2003

Noninvasive molecular-imaging technologies are providing researchers with exciting new opportunities to study small-animal models of human disease. With continued improvements in instrumentation, identification of better imaging targets by genome-based approaches, and design of better imaging probes by innovative chemistry, these technologies promise to play increasingly important roles in disease diagnosis and therapy.
Physics Forged in the Tripos
Authors: Porter Theodore M.
Published: October 2003

Masters of Theory
Cambridge and the Rise of Mathematical Physics. by Andrew Warwick. University of Chicago Press, Chicago, 2003. 586 pp. $85. ISBN 0-226-87374-9. Paper, $29. ISBN 0-226-87375-7.

Warwick explores the influences that the training of Cambridge mathematicians had on the development of theoretical physics in the late 19th and early 20th centuries.
In Vitro-In Vivo Model for Evaluating the Antiviral Activity of Amprenavir in Combination with Ritonavir Administered at 600 and 100 Milligrams, Respectively, Every 12 Hours
Authors: Preston Sandra L. , Piliero Peter J. , Bilello John A. , Stein Daniel S. , Symonds William T. , Drusano George L.
Published: October 2003

The study objective was to evaluate the pharmacodynamics of amprenavir in an in vitro system, develop an exposure target for maximal viral suppression, and determine the likelihood of target attainment based on the pharmacokinetics of amprenavir and ritonavir in human immunodeficiency virus (HIV)-infected patients. Population pharmacokinetic data were obtained from 13 HIV-infected patients receiving amprenavir and ritonavir in doses of 600 and 100 mg, respectively, every 12 h. A 2,500-subject Monte Carlo simulation was performed. Target attainment was also estimated for a target derived from clinical data. Maximal viral suppression (in vitro) was achieved when amprenavir free-drug concentrations remained greater than four times the 50% effective concentration (EC50) for 80% of the dosing interval. At an amprenavir EC50of 0.03 μM, the likelihood of target attainment is 97.4%. For reduced-susceptibility isolates for which the EC50s are 0.05 and 0.08 μM, target attainment is 91.0 and 75.8%, respectively. For the clinical target of a trough concentration/EC50ratio of 5, the target attainment rates were similar. Treatment with amprenavir and ritonavir at doses of 600 and 100 mg, respectively, twice a day provides excellent suppression of wild-type isolates and reduced-susceptibility isolates up to an EC50of 0.05 μM. Even at 0.12 μM, target attainment likelihood exceeds 50%, making this an option for patients with extensive exposure to protease inhibitors when this treatment is used with additional active antiretroviral agents.
Pharmacology of Novel Heteroaromatic Polycycle Antibacterials
Authors: Gross M. , Bürli R. , Jones P. , Garcia M. , Batiste B. , Kaizerman J. , Moser H. , Jiang V. , Hoch U. , Duan J.-X. , Tanaka R. , Johnson K. W.
Published: October 2003

Heteroaromatic polycycle (HARP) compounds are a novel class of small (
M
w
, 600 to 650) DNA-binding antibacterials. HARP compounds exhibit a novel mechanism of action by preferentially binding to AT-rich sites commonly found in bacterial promoters and replication origins. Noncovalent binding in the minor groove of DNA results in inhibition of DNA replication and DNA-dependent RNA transcription and subsequent bacterial growth. HARP compounds have previously been shown to have potent in vitro activities against a broad spectrum of gram-positive organisms. The present report describes the extensive profiling of the in vitro and in vivo pharmacology of HARP antibacterials. The efficacies of representative compounds (GSQ-2287, GSQ-10547, and GSQ-11203), which exhibited good MIC activity, were tested in murine lethal peritonitis and neutropenic thigh infection models following intravenous (i.v.) administration. All compounds were efficacious in vivo, with potencies generally correlating with MICs. GSQ-10547 was the most potent compound in vitro and in vivo, with a 50% effective dose in the murine lethal peritonitis model of 7 mg/kg of body weight against methicillin-sensitive
Staphylococcus aureus
(MSSA) and 13 mg/kg against methicillin-resistant
S. aureus
(MRSA). In the neutropenic mouse thigh infection model, GSQ-11203 reduced the bacterial load (MRSA and MSSA) 2 log units following administration of a 25-mg/kg i.v. dose. In a murine lung infection model, treatment with GSQ-10547 at a dose of 50 mg/kg resulted in 100% survival. In addition to determination of efficacy in animals, the pharmacokinetic and tissue disposition profiles in animals following administration of an i.v. dose were determined. The compounds were advanced into broad safety screening studies, including screening for safety pharmacology, genotoxicity, and rodent toxicity. The results support further development of this novel class of antibiotics.
Quinine Pharmacokinetic-Pharmacodynamic Relationships in Uncomplicated Falciparum Malaria
Authors: Pukrittayakamee S. , Wanwimolruk S. , Stepniewska K. , Jantra A. , Huyakorn S. , Looareesuwan S. , White N. J.
Published: October 2003

The relationships between the pharmacokinetic properties of quinine during a 7-day treatment course and the therapeutic response were studied in 30 adult patients with uncomplicated falciparum malaria monitored for ≥28 days. All patients received a 7-day oral quinine regimen either alone (n= 22) or in combination with rifampin (n= 8). The median fever clearance time was 58.5 h, and the mean ± standard deviation parasite clearance time was 73 ± 24 h. After recovery, six patients had recrudescences ofPlasmodium falciparummalaria and seven had delayed appearances ofP. vivaxinfection between days 16 and 23. Between the patients with and without recrudescences, there were no significant differences either in fever clearance time or parasite clearance time or in the overall pharmacokinetics of quinine and 3-hydroxyquinine. Patients for whom the area under the concentration-time curve from 3 to 7 days for quinine in plasma was <20 μg · day/ml had a relative risk of 5.3 (95% confidence interval = 1.6 to 17.7) of having a subsequent recrudescence of infection (P= 0.016). Modeling of these data suggested an average minimum parasiticidal concentration of quinine in plasma of 3.4 μg/ml and an MIC of 0.7 μg/ml for uncomplicated falciparum malaria in Thailand. To ensure a cure, the minimum parasiticidal concentration must be exceeded during four asexual cycles (>6 days).