bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous measurement of recombination lifetime and surface recombination velocity
Authors: Eränen S. , Blomberg M.
Published: February 2003

We describe a method to determine the carrier recombination lifetime and surface recombination velocity of semiconductor samples in a single photoconductivity decay measurement. The method is based on the observation of the slope of the photoconductivity signal in the long time scale decay tail in the usual fashion, and, in addition, just after the short laser pulse, which generates the excess carriers. In this article the theory of the measurement and some experimental results on silicon wafers with different surface conditions are presented.
Electrical and optical properties of Au in cadmium telluride
Authors: Molva E. , Francou J. M. , Pautrat J. L. , Saminadayar K. , Dang Le Si
Published: February 2003

Gold diffused CdTe crystals have been studied by electrical and optical measurements, involving admittance spectroscopy, low temperature photoluminescence excited with a tunable dye laser, absorption, and magneto-optical measurements. It has been shown that Au introduces an acceptor level at 263 meV above the valence band. Its properties can be understood in terms of classical deep acceptor-like states with a d10 impurity core. Substitutional acceptor Au concentrations up to ∼5×1016 cm−3 could be obtained with a two-step diffusion process. Otherwise, simple diffusions at temperatures higher than 600 °C lead to the formation of complex centers. Some complex-bound exciton lines have been identified. They have been tentatively attributed to neutral substitutional-interstitial associates. Magneto-optical studies have shown that the acceptor Au bound exciton ground state was a J=1/2 state, and have confirmed that Au acceptor was indeed on Cd site in a Td symmetry. The diamagnetic shift of the neutral acceptor bound exciton complex is well explained in terms of the pseudo-donor model. Also the cubic crystal field effects have been found to be very important.
Measurement of electron mobility in epitaxial heavily-phosphorus-doped silicon
Authors: del Alamo Jesús A. , Swanson Richard M.
Published: February 2003

Electron mobility and electron concentration have been measured in epitaxial heavily-P-doped Si grown from a SiH4/PH3 system. The electron concentration range covered is from 1.8×1019 to 1.7×1020 cm−3. Mobility measurements agree within 4% with previous experimental data from W. R. Thurber, R. L. Mattis, Y. M. Liu, and J. J. Filliben [J. Electrochem. Soc. 127, 1807 (1980)] in as-grown material, and G. Masetti, M. Severi, and S. Solmi [IEEE Trans. Electron. Devices ED-30, 764 (1983)] in diffused, and in implanted and annealed Si. The electrical resistivity versus electron concentration also agrees within 5% with these other data. Full activation of P is found up to the highest doping level of 1.7×1020 cm−3.
Hall effect and resistivity in liquid-phase-epitaxial layers of HgCdTe
Authors: Lou L. F. , Frye W. H.
Published: February 2003

The Hall effect and resistivity have been measured in liquid-phase-epitaxial (LPE) HgCdTe layers in the temperature range between 16 and 300 K. The composition of the material covers the wavelength range from 3 to 12 μm. The results obtained from a broad sample base have been systematically analyzed and categorized. Although much of the data follows classical behavior and is readily understood, it has now become possible to analyze quantitatively the variety of other observed Hall-effect data in some of the LPE HgCdTe layers by making use of a theoretical model for multilayer structure. This allows such fundamental properties as surface charge density, bulk carrier concentration, surface and bulk mobility, and dopant concentration in double-layer heterojunctions to be extracted from the experimental data otherwise classified as ‘‘anomalous’’ and not analyzable previously. Controlled experiments have been carried out to show the dependence of Hall-effect measurements on layer thicknesses and various surface conditions. Evidences are described that identify three types of structure that produce the observed anomalous data: n skin on p layer, n layer on p layer, and n skin on n layer. The layer model is outlined, emphasizing its development for application to LPE HgCdTe. The temperature-dependent mobilities of both electrons and holes required in the model are derived from the large data base. Allowance is also made for the magnetic-field dependence of the measured Hall coefficient.
Characterization of metallophthalocyanine-metal contacts: Electrical properties in a large frequency range
Authors: Boudjema Bouzid , Guillaud Gérard , Gamoudi Maxime , Maitrot Monique , André Jean-Jacques , Martin Michel , Simon Jacques
Published: February 2003

The dark electrical properties of metallophthalocyanine-metal contacts are studied in an extended frequency range (10−3–105 Hz). The measurements show that the standard Schottky model cannot be applied to metallo-organic semiconductors. Three different contributions to the admittance may be distinguished. Over the very first few angstroms of the semiconductor extends a surface-charge layer associated with a high capacitive term. The surface-charge capacitance is only slightly dependent upon superimposed dc voltages. The so-called space-charge region extends below the surface-charge layer over approximately 2000–4000 Å. The properties of this space-charge region are, however, dramatically different from those found in monocrystalline inorganic semiconductors. The corresponding capacity is almost independent of any dc superimposed voltage. At the same time, the resistance of the space-charge region is highly dependent on externally applied dc voltages. The I-V relationship seems to indicate a Frenkel–Poole mechanism of charge detrapping. Finally, the rest of the metallo-organic layer shows the properties of the bulk material. Due care must be taken when interpreting usual capacitance-voltage relationships (1/C2-vs-V plots). Apparent variations of the overall capacitance do not correspond to properties of the space-charge region. A close examination of the measurements over an extended range of frequencies is necessary to correctly derive the electrical properties of the metallo-organic semiconductor.
Epitaxial growth of superconducting BaPb1−xBixO3 thin films
Authors: Suzuki Minoru , Murakami Toshiaki
Published: February 2003

Superconducting BaPb1−xBixO3 (BPB) thin films have been epitaxially grown on sapphire (011̄2) and SrTiO3 (100) single-crystal substrates at around 700 °C by the planar rf magnetron sputtering method, under relatively high pressure Ar-O2 mixed gas atmosphere. As-sputtered BPB films on SrTiO3 (100) exhibit superconductivity with a sharp transition at Tc=10 K. The resistivity, 8×10−4 Ω cm, is more than one order of magnitude smaller, and the critical current, 2.5×105 A/cm2, is more than two orders of magnitude larger than those reported earlier. The Hall mobility is 3.0 cm2/V s. The films are confirmed to be single crystals directly by the absence of grain boundary Josephson junctions, which polycrystalline BPB inherently possesses, as well as by the x-ray diffraction and the reflection electron diffraction analysis.
Positive charging of fluorinated ethylene propylene copolymer (Teflon) by irradiation with low-energy electrons
Authors: Gross B. , von Seggern H. , West J. E.
Published: February 2003

Starting with electron energies above a few keV, all materials show an increase in the number of secondary and backscattered primary electrons with decreasing primary energy. The number of secondary plus backscattered electrons becomes equal to the number of primaries at two energies called the first and second crossover points. Between these energies the number of backscattered primaries and of secondaries exceeds the number of incoming primaries. For Teflon FEP the higher-energy crossover (second crossover) point occurs at about 1.6 keV. Between this energy and the first crossover (at a few hundred eV), holes are generated in the surface region of the material. This effect can be used to charge the surface of an insulating dielectric positively by negatively biasing the metallized rear during charging and subsequent discharging of the rear electrode after irradiation.
Silicides formation for refractory metal alloys (Ta-V and Ti-V) on Si
Authors: Appelbaum A. , Eizenberg M.
Published: February 2003

Contact reactions between a Si substrate and thin films of Ta-V and Ti-V bilayers and codeposited alloys have been studied. The interdiffusion and silicide formation have been analyzed by Auger electron spectroscopy and x-ray diffraction. For both alloys the as-deposited films are in a single phase structure (solid solution), and metal rich compounds (M5Si3), which are not observed for M/Si, are found at the early stages of reaction prior to the appearance of the expected stable silicides. For the Ta-V system the uniform in-depth distribution of the alloy constituents is maintained even after their silicides formation and both compounds TaSi2 and VSi2 are mutually dissolved. The second system Ti-V, however, reveals nonuniform redistribution following the interaction with Si; enrichment with titanium silicide at the substrate interface is observed. The great affinity of Ti to form a silicide on Si is manifested in the case of the bilayer structure of Ti/V/Si when Ti atoms from the outer region penetrate through the inner V layer and form titanium silicide at the Si interface.
Mechanical strength of silicon crystals as a function of the oxygen concentration
Authors: Yonenaga Ichiro , Sumino Koji , Hoshi Kinji
Published: February 2003

Mechanical strengths of silicon crystals involving oxygen at various concentrations up to 1018 atoms/cm3 are investigated with the use of crystals grown by the Czochralski technique in magnetic field. Oxygen atoms dispersed on interstitial sites at any concentration have almost no influence on the dislocation processes that control the mechanical behavior of a dislocation-free crystal. Oxygen atoms in a dislocated crystal lock dislocations effectively and result in the strengthening of the crystal. Locking of dislocations becomes more effective as the concentration of oxygen in the crystal increases. Softening of crystals due to precipitation of oxygen at elevated temperature occurs rapidly in highly concentrated crystals with oxygen, but is almost absent or takes place slowly in crystals of oxygen concentrations lower than about 5×1017 atoms/cm3.
Evaluation of a charge-coupled device for high-energy particle detection
Authors: Bhuiya Akram H.
Published: February 2003

A study has been made to evaluate the application of a charge-coupled device as a detector of minimum-ionizing, charged particles. The experiment was performed with a Fairchild CCD111, a linear array 256-element charge-coupled device. It is concluded that the CCD111 should be able to detect high-energy particles at low operating temperatures (∼−75 °C) with exposure times of less than 10-ms duration. Finally, a speedy readout system is described for practical application in high-energy experiments.
An x-ray diffraction study of lattice imperfections in cold-worked face-centered-cubic alloys. V. Silver-aluminum (α phase)
Authors: Ghosh S. K. , De M. , Sen Gupta S. P.
Published: February 2003

X-ray peak-shift, peak-asymmetry, and peak-broadening analyses have been performed on cold-worked α-phase Ag-Al alloys containing 5.8, 9.2, 15.8, and 18.2 at. % Al based on the diffraction profiles recorded with copper radiation and a counter diffractometer equipped with (100) LiF crystal monochromator. Following the procedures adopted earlier in this series of work, a detailed analyses of the recorded profiles revealed quantitative estimates of the microstructural parameters, namely, propensity of stacking faults (intrinsic, extrinsic, and twin faults), rms microstrains, coherent domain sizes, long-range residual stresses, lattice parameter changes, dislocation density, and stacking fault energy. As in earlier alloy systems of this series, the results indicate an increase in the stacking fault density, primarily of intrinsic character with increasing solute concentration, and these are mainly responsible for the observed peak shifts and domain size broadening. Small asymmetry in the profiles has been found to be due to the presence of extrinsic stacking faults, relatively less in magnitude compared to intrinsic ones while the deformation twin faults are almost absent. The dislocation density ρ has been evaluated from the anisotropic values of the coherent domain sizes and rms microstrains. The stacking fault energy γ0 for pure silver has been estimated to be 6–9 mJ/m2, which is lower than the previously reported values. Finally, annealing experiments with Ag-5.8 at. % Al alloy do not show any detectable evidence of solute segregation at stacking faults.
Effect of substrate temperature on molecular beam epitaxial GaAs growth using As2
Authors: Erickson L. Peter , Mattord Terry J. , Carpenter Gregory L. , Palmberg Paul W. , Pearah P. J. , Klein M. V. , Morkoç Hadis
Published: February 2003

The effect of substrate temperature on Si incorporation, electron mobility, growth rate, and surface morphology in GaAs films grown by molecular beam epitaxy using a dimeric arsenic (As2) source has been investigated. As the substrate temperature was raised from 570 to 700 °C, the measured carrier concentration and electron mobility were observed to decrease while the Si and C acceptor peaks detected in low-temperature photoluminescence measurements were seen to increase, indicating increased carrier compensation with increasing substrate temperature. The epitaxial GaAs growth rate was nearly independent of substrate temperature with the use of As2, in contrast with the observed reduction in growth rate for substrate temperatures >640 °C when the tetrameric arsenic (As4) is employed. Surface defects on films grown with As2 were found generally to increase with substrate temperature; however, at 680 °C defect densities could be reduced tenfold or more by increasing the arsenic overpressure. No such decrease was observed in films grown with As4.
Wetting of aluminum electrodes with mercury
Authors: Sudarshan T. S. , Lim M. H. , Hefley P. L. , Thompson J. E.
Published: February 2003

The liquid metal coating (wetting) of metal surfaces has considerable interest from both theoretical and practical standpoints. This paper describes a practical method for wetting materials such as aluminum and elkonite (70% tungsten and 30% copper) by mercury (Hg), to result in a strongly adhering coating. The readiness of Al to form an oxide layer generally inhibits wetting by Hg. The technique presented in this paper involves protecting a cleaned substrate surface by coating it with a Hg soluble, stable material such as Cu, until the substrate surface is brought into contact with Hg, to produce surface complexing. Some practical applications of liquid metal wetting are reviewed. The theory of wetting is also briefly reviewed. A plasma technique which has been successfully employed to Hg wet some materials which are known to be difficult to be wetted by Hg, is also briefly reviewed.
Magnetic-flux trapping characteristics of thin-film Pb alloys as electrodes of Josephson junctions
Authors: Uchida N. , Enpuku K. , Yoshida K. , Irie F.
Published: February 2003

Magnetic-flux trapping characteristics of thin-film Pb alloys including Au and Bi are studied experimentally, which are used for Josephson junction integrated circuits. The amount of the magnetic flux trapped in thin-film Pb alloys is estimated from the measurement of the quasiparticle-current increment of Josephson junctions, which are fabricated with Pb alloys as junction electrodes. An array of Josephson junctions is used in order to observe the spatial distribution of the magnetic-flux density in thin films. The observed magnetic-flux behavior in thin films was apparently similar to that in nonideal bulk type-II superconductors; magnetic-flux distribution was similar to that expected from the so-called pinning model, and surface barrier became large in weak magnetic fields. From the analysis of the observed data, the parameter characterizing the degree of flux trapping has been obtained, with which effects of Au and Bi on flux trapping are evaluated quantitatively. It was shown that the addition of Au increases flux trapping presumably due to strong pinning centers originated from normal precipitates of Au, and that the addition of Bi decreases flux trapping, which may be attributed to the enhancement of the London penetration depth of PbBi films.
Corrosion resistance of nitrogen implanted iron foils: A conversion electron Mössbauer effect study
Authors: Dorik Y. S. , Bhide V. G. , Kanetkar S. M. , Ghaisas S. V. , Chaudhari S. M. , Ogale S. B.
Published: February 2003

Conversion electron Mössbauer spectroscopy (CEMS) has been employed to study the effect of ion implantation and subsequent annealing on the oxidation kinetics of iron foils. 80-keV N+2 ions were implanted in iron foils at a dose of 2×1016 ions/cm2 and a number of such samples were subjected to thermal oxidation treatment. Both CEMS and the conventional gravimetric techniques bring out the fact that the as-implanted samples exhibit enhanced oxidation while the implanted and annealed samples show considerably reduced oxidation as compared to that of the virgin iron foils. Ion implantation produces point defects and compressive stresses in the implanted layers. Whereas the former enhances the oxidation rate, the latter tends to inhibit it in the case of iron foils. The vacuum heat treatment anneals out the point defects, stabilizes the compressive stresses, and favors migration of nitrogen atoms towards grain boundaries and dislocation pipes leading to their passivation thereby inhibiting the oxidation of the iron foils. Confirmatory support for this analysis is derived by extending these studies to the study of the oxidation of iron foils implanted with Ar+ ions and of iron films in which stresses were induced by cooling the films deposited at high temperature on substrates of molybdenum whose thermal coefficient of expansion differs considerably from that of iron.
Reply to ‘‘Comments on ‘Material nonlinear piezoelectric coefficients for quartz’ ’’
Authors: Brendel R.
Published: February 2003

An Attempt to obtain an expression of the nonlinear polarization induced by static stress as a function of the electroelastic coefficients implies the knowledge of the relations between piezoelectric strain and stress coefficients. Such relations themselves depend on all linear and nonlinear coefficients of quartz which are not all known today.
InGaAsP double-heterostructure optical waveguides with p+-n junction and their electroabsorption
Authors: Okamoto K. , Matsuoka S. , Nishiwaki Y. , Yoshida K.
Published: February 2003

InGaAsP three-dimensional optical waveguides with p+-n junctions are described. A p+-InGaAsP/n-InGaAsP/n+-InGaAsP double-heterostructure rib-type waveguide, which is suitable for monolithic integrations, was fabricated on an n+-InP substrate by liquid-phase epitaxial growth and chemical etching. Transmission loss as low as α=1.2 cm−1 was observed for deep-etched rib-structure passive waveguides at λ=1.318 μm TE fundamental mode. Additionally, electroabsorption of the waveguide layer material, In0.78Ga0.22As0.48P0.52, was determined at Eg −ℏω=0.09 eV. This measured electroabsorption will be a good guide for designing InGaAsP electro-optic and/or electroabsorption-type modulators.
The effect of plasticizer on the polarization of poly(vinylidene fluoride) films
Authors: Sen A. , Scheinbeim J. I. , Newman B. A.
Published: February 2003

Plasticized and unplasticized, unoriented phase II poly(vinylidene fluoride) (PVF2) films were poled at fields ranging from 0.5 to 1.25 MV/cm at room temperature for 10 min. X-ray diffraction data revealed that at fields near 1.0 MV/cm, a change in conformation to produce phase I occurred. The amount of phase I produced was found to be significantly higher in the case of plasticized film. The plasticized films also showed higher piezoelectric strain coefficient d31, stress coefficient e31, and pyroelectric coefficient P y, as compared to unplasticized films subjected to identical poling conditions. In a similar study of oriented phase I films (obtained by stretching plasticized and unplasticized phase II films), poling fields ranging from 0.5 to 2.0 MV/cm were used. The Bragg angle for the (110), (200) reflection was found to be higher for the poled plasticized films (compared to the poled unplasticized films) with 2θ increasing with increasing plasticizer content. Py, e31, and d31 were also higher as compared to the unplasticized films.
Phase behavior in copolymer blends of polystyrene and poly(o-chlorostyrene-co-p-chlorostyrene)
Authors: ten Brinke Gerrit , Rubinstein Ellen , Karasz Frank E. , MacKnight W. J. , Vukovic R.
Published: February 2003

The miscibility of random copolymers of o-chlorostyrene and p-chlorostyrene [P(oClS-pClS)] with polystyrene (PS) has been studied by differential scanning calorimetry (DSC). A miscibility ‘‘window’’ was found, extending in copolymer composition from about 68 to 98 mole % o-chlorostyrene at a temperature of 150 °C. The maximum in the miscibility window occurred at approximately 170 °C and a composition of 83 mole % o-chlorostyrene. This result differs only slightly from theoretical predictions based on interaction parameters previously calculated from miscibility behavior in blends of poly(2,6-dimethyl-1,4-phenylene oxide) with P(oClS-pClS), poly(styrene-co-o-chlorostyrene) and poly(styrene-co-p-chlorostyrene). The implication of this result for the numerical values of the six interaction parameters required to describe these blends is discussed.
A continued investigation of the damped Debye lattice model in the primary transition region
Authors: Chao Yah Lih , Aklonis J. J.
Published: February 2003

The damped Debye lattice model predicts rather unusual behavior for relaxation of certain polymer systems in the primary transition region. In particular, certain compatible blends are predicted to sharpen their stress relaxation master curves in this region upon dilution. We recently showed that this predicted behavior was observed for the blend of polystyrene and poly (2,6-dimethylphenylene oxide). Here we have investigated the generality of such behavior by extending our study to the blend of polystyrene and poly (α-methylstyrene). Once again, the predicted behavior was observed. However, specific differences between the behavior of these two blend systems were noted.
Predictions of nucleation theory applied to Ehrenfest thermodynamic transitions
Authors: Barker R. E. , Campbell K. W.
Published: February 2003

This paper deals with the applicability of classical nucleation theory to second-order thermodynamic transitions in the Ehrenfest sense. A mathematical formulation is presented in which physically meaningful expressions for a critical nucleus size as well as a critical activation energy barrier for second-order transitions are derived as functions of the degree of undercooling θ, interfacial energy γ, heat capacity difference ΔCp, specific volume of the transformed phase υβ, and the equilibrium transition temperature Tt. These expressions are rc=4υβTt/(ΔCp)2θ2 and Δ𝒢c=(64π/3)γ 3υ2β(Tt)2/ (ΔCp)2θ4. These results arise from the expansion of the effective free energy in a Maclaurin series and evaluating the expansion coefficients in terms of thermodynamic relations. As a consequence of this manipulation a break is made from the customary approximations which are normally employed in elementary homogeneous nucleation theory. Secondly, this approach yields nonlinear correction terms which can be applied when calculating the critical nucleus size and critical activation energy barrier for a first-order transition. Finally, graphical descriptions of systems undergoing first- and second-order Ehrenfest transitions are presented in order to give a semiquantitative meaning to the expressions derived with this approach.
Latent hardening in high-density polyethylene
Authors: Chaki T. K. , Li J. C. M.
Published: February 2003

When a parallelopiped specimen is compressed in the x direction (primary deformation) while holding the y dimension unchanged by a vise, the specimen is anisotropically hardened as follows: When the y direction is subsequently compressed while holding the x dimension unchanged the flow stress is higher than the case without the primary deformation. This is similar to the latent hardening in single crystals. On the other hand, if the second compression is in the z direction instead of the y direction, a softening results. Since this second compression reverses the primary deformation, it is similar to the Bauschinger effect. Both effects are reported here together with the results of two successive compressions in two mutually perpendicular directions without any constraints in either compression.
Extended x-ray absorption fine structure: Studies of zinc-neutralized sulfonated polystyrene ionomers
Authors: Ding Y. Samuel , Yarusso David J. , Pan H. K. David , Cooper Stuart L.
Published: February 2003

Extended x-ray absorption fine structure (EXAFS) measurements were performed on a series of zinc-neutralized sulfonated polystyrene ionomers and the local structure around the zinc atom was determined. An interference effect in the EXAFS signal between sulfur and oxygen atoms was found to be significant in these materials. A model for the local structure in the zinc-neutralized sulfonated polystyrene ionomers is proposed which suggests a highly ordered tetrahedral coordination of oxygen around the zinc atoms at a distance of 1.97±0.02 Å. In addition there are four sulfur atoms and four oxygen atoms at a distance of 3.15±0.05 Å. No zinc-zinc coordination within 5 Å was detected in this study.
Structural, dielectric, and thermal investigation of the Curie transition in a tetrafluoroethylene copolymer of vinylidene fluoride
Authors: Lovinger Andrew J. , Johnson G. E. , Bair H. E. , Anderson E. W.
Published: February 2003

To confirm and extend further our previous prediction of a Curie transition in PVF2, we examined a copolymer of it with tetrafluoroethylene (81 mol % VF2). The tetrafluoroethylene units serve to render this copolymer equivalent to PVF2 of a slightly increased head-to-head content. Contrary to other reports, we have detected a Curie transition in this material using x-ray diffraction, dielectric, and calorimetric techniques. The ferroelectric-to-paraelectric transformation is barely perceptible because it begins at ∼122 °C (which is only slightly below the main melting point) and is rapidly overtaken by melting. However, the reverse (paraelectric-to-ferroelectric) transition is detected unequivocally in the vicinity of 110–115 °C because of the metastability of the paraelectric phase that crystallizes from the melt. The dielectric peaks associated with this Curie transition are clearly separated from any contribution of bulk conduction. The characteristics of this transition are analogous to those found in copolymers of VF2 with trifluoroethylene and thus indicate that such ferroelectric behavior is inherent to PVF2 and does not reflect influences of any particular comonomer.
Self-diffusion of C6F6 in filled rubbery polymers
Authors: von Meerwall E. , Shook D. , Min K. J. , Kelley F. N.
Published: February 2003

We have used the pulsed-gradient spin-echo nuclear magnetic resonance method to measure self-diffusion of C6F6 dissolved in crosslinked polybutadiene containing embedded styrene-divinyl benzene beads. Both binder matrix and filler particles are swellable, but long-range diluent self-diffusion proceeds mainly in the matrix, interstitially between the filler particles. Time dependence of diffusion is clearly observed, and is interpreted in terms of the dimensions of the interstitial regions and an effective permeability of their boundaries. The dependence of diffusion on filler and diluent content are discussed.
Polarization behavior during high field poling of poly(vinylidene fluoride)
Authors: von Seggern H. , Wang T.T.
Published: February 2003

The polarization process which takes place during electric poling of poly(vinylidene fluoride) is investigated by measuring the time dependence of currents in poling circuits with varying RC time constants. For applied voltages between 3 and 8 kV (average field strengths 1.2–3.2 MV/cm) and RC values between 10 and 10−3 s, the current-time behavior, normalized by the corresponding RC time constants and initial current values, can be described by a single curve (quasi-steady state). Such a representation indicates that the switching of polarization is simply a voltage- or field-induced effect. A phenomenological description of the poling process is presented which allows one to determine the dependence of polarization with respect to the voltage across the sample. The corresponding density function shows a steep rise in polarization at about 2400 V (average electric field strength 1 MV/cm) followed by an exponentially decaying tail toward higher voltages. Implication of such a distribution is discussed briefly.
Spectral range of operation of coupled-mode optical filters
Authors: Laurenti J. P.
Published: February 2003

The spectral range of operation of optical coupled-mode filters (CMF) is investigated. The CMF principle is based upon the stress-induced energy transfer between orthogonal polarized optical modes, which occurs in birefringent materials at the isotropic wavelength where phase-matching is ensured. A nonexhaustive list of birefringent materials which exhibit an isotropic wavelength is drawn up. The whole visible spectral range is covered continuously by using mixed graded-band-gap hexagonal crystals such as CdS-CdSe and ZnS-CdS. This range is extended up to 2.1 μm by using piezobirefringent cubic compounds. Materials with other crystalline structures enable the extension of this spectral range down to 1200 Å. The optical activity of chalcopyrite-structure semiconductors can advantageously replace stress-induced mode coupling.
Comprehensive study of a CO2 laser using electrochemical transformation of organic compounds
Authors: Midorikawa K. , Tashiro H. , Namba S.
Published: February 2003

The relationship between the reaction products and the output power in the CO2 laser using electrochemical transformation of organic compounds (ECTO) was experimentally investigated. Necessary properties of organic compounds for the efficient operation of the ECTO CO2 laser are discussed. The influence of absorption loss due to fed organic vapor was also revealed by studying line-tuning characteristics of the ECTO CO2 laser.
Criteria for physical domains in laboratory and solid-state plasmas
Authors: Liboff Richard L.
Published: February 2003

Physical domains relevant to laboratory and solid-state plasmas are described in terms of relevant characteristic parameters. Strongly- and weakly-coupled classical plasmas are divided according to the plasma parameter Γ, whereas quantum and classical domains are separated according to the thermal DeBroglie wavelength Λ, nondimensionalized through mean interparticle spacing. These parameters are found to obey the relation Λ2=(π/16)1/3(kBT/R*)Γ4/3, where T is temperature and the Rydberg constant R* includes the dielectric constant of the medium and effective mass of charge carriers. The weakly-coupled degenerate plasma is described in terms of the quantum compression parameter rs, which represents interparticle spacing measured in Bohr radii. An alternative description of this domain is given in terms of a new quantum parameter (labeled ΓQ) whose definition includes the Thomas–Fermi screening length in place of the Debye length in the classical plasma parameter. A graphical display in terms of appropriately nondimensionalized particle number density and temperature, respectively, reveals that all nonrelativistic, nonmagnetic plasma domains are included over the unit area of this graph. Application of these findings is made to GaAs and InP at 300 and 1000 °K in the intrinsic domain. Incorporating recent empirical expressions for effective mass, energy gap, and Fermi energy, it is found that at the lower temperature, the conducting solid-state plasmas of these semiconductors are weakly coupled and classical. At the higher temperature, due primarily to increased carrier concentration, the plasmas grow degenerate.
Hodograph: A useful geometrical tool for solving some difficult problems in dynamics
Authors: Apostolatos Theocharis A.
Published: February 2003

The hodograph is very useful for solving complicated problems in dynamics. By simple geometrical arguments students can directly obtain the answer to problems that would otherwise be complicated exercises in algebra. Although beyond the level of undergraduates, we also use the hodograph to calculate by variational geometrical techniques, the well-known brachistochrone curve, thus illustrating this approach.
Eyesight and the solar Wien peak
Authors: Overduin James M.
Published: February 2003

It is sometimes said that humans see best at yellow–green wavelengths because they have evolved under a Sun whose blackbody spectrum has a Wien peak in the green part of the spectrum. However, as a function of frequency, the solar blackbody spectrum peaks in the infrared. Why did human vision not evolve toward a peak sensitivity in this range, if the eye is an efficient quantum detector of photons? The puzzle is resolved if we assume that natural selection acted in such a way as to maximize the amount of energy that can be detected by the retina across a range of wavelengths (whose upper and lower limits are fixed by biological constraints). It is then found that our eyes are indeed perfectly adapted to life under a class G2 star. Extending this reasoning allows educated guesses to be made about the kind of eyesight that might have evolved in extrasolar planetary systems such as that of the red dwarf Gliese 876.
Resource Letter: LBOT-1: Laser-based optical tweezers
Authors: Lang Matthew J. , Block Steven M.
Published: February 2003

This Resource Letter provides a guide to the literature on optical tweezers, also known as laser-based, gradient-force optical traps. Journal articles and books are cited for the following main topics: general papers on optical tweezers, trapping instrument design, optical detection methods, optical trapping theory, mechanical measurements, single molecule studies, and sections on biological motors, cellular measurements and additional applications of optical tweezers.
MULTIPLE TENDONS OF THE ABDUCTOR POLLICIS LONGUS MUSCLE: A CASE REPORT
Authors: Akan Mithat , Gideroğlu Kaan , Çakir Baris
Published: February 2003

In the case presented below, we observed abductor pollicis longus (APL) dividing into five sections shortly after exiting the first compartment. Many variations of APL may be seen and it is essential to know these variations in the practice of hand surgery.
ISOLATED RADIAL NERVE PALSY IN A NEWBORN: REPORT OF TWO CASES
Authors: Deshmukh N. V. , Phillips G. E.
Published: February 2003

Two newborns with history of difficult birth were diagnosed within 24 hours after birth with isolated radial nerve palsy. Both newborns recovered completely. Awareness and multidisciplinary approach is essential.
INTERPOSITION ARTHROPLASTY FOR OSTEOARTHRITIS OF TRAPEZIO METACARPAL JOINT: RESULTS OF A MODIFIED INCISION AND TECHNIQUE OF INTERPOSING WITH EARLY MOBILISATION
Authors: Maqsood M. , Chenthil Kumar N. R. , Noorpuri B. S. W.
Published: February 2003

Sixty flexor carpi radialis (FCR) tendon interposition arthroplasties were done using a modified incision from Froimson's approach for osteoarthritis (OA) of thumb carpo metacarpal joint (CMCJ) The tendon was made to resemble an anchovy fillet to preserve pillar length (average 7.5 mm). There was no incidence of injury to the superficial branch of the radial nerve. Graded mobilisation was commenced at two weeks. Our average follow-up for five and a half years shows good results, viz. pain relief (100%), power grip (21 kg), pinch grip (4.2 kg), tripod grip (5.5 kg), key grip (6.5 kg), ability to touch base and tip of little finger (91.6%) and (96.6%), respectively. Activities of daily living (ADL) without pain in turning a key (96.7%), opening jar top (100%), bottle top (93.4%), wringing cloth (86.7%), and using scissors (88.4%). None of them suffered reflex sympathetic dystrophy (RSD) and mobility was almost equal to the non-operated hand. Our experience with this modified incision and technique of interposing with early mobilisation has shown good functional outcome with no significant operative or postoperative complications.
STATIC SCAPHOLUNATE DISSOCIATION DIAGNOSED BY SCAPHOLUNATE GAP VIEW IN WRISTS WITH OR WITHOUT DISTAL RADIUS FRACTURES
Authors: Akahane M. , Ono H. , Nakamura T. , Kawamura K. , Takakura Y.
Published: February 2003

This prospective study investigated static scapholunate dissociation (SLD) in wrists associated with distal radius fractures. SLD was detected as a widening of the scapholunate (SL) joint interval by SL gap view. Ninety-six distal radius fractures and 154 normal wrists were investigated by SL gap view, which is better for detecting SLD than the standard posteroanterior (PA) view. Incidences of non-symptomatic SLD detected by SL gap view in normal wrists increased by age. In the young age bracket, incidences of SLD in distal radius fractures were significantly higher than in normal wrists. Our results indicated that in patients younger than 30 years old, SLD in distal radius fractures was a fracture-caused abnormality. In those over 30, ascribing SLD to the fracture was difficult. Close examinations, like arthroscopy and dynamic cineradiography, need to be made in patients with SLD associated with distal radius fractures, especially in those younger than 30.
PREVENTION OF DAMAGE CAUSED BY SURAL NERVE WITHDRAWAL FOR NERVE GRAFTING
Authors: Brunelli Giorgio A.
Published: February 2003

Sural nerve withdrawal in peripheral nerve surgery is commonly performed for grafting nerve lesions with gap. Notwithstanding its popular use, this procedure is not entirely without fault as painful neuromas can occur after the withdrawal.

We have treated 24 cases of painful neuromas of sural nerve after withdrawal; 11 of which were treated surgically.

A safe procedure to cure and to prevent such neuromas is described — the electrical coagulation of the stump of the nerve by slowly increasing the intensity of the current. This procedure has been devised based on the fact that electrically burnt patients do not produce painful neuromas.

An experimental histological study performed on rats demonstrated that slow electrical burning of the stump of a severed nerve prevents the formation of intraneural fibrosis which, on the contrary, forms abundantly when the cut nerve is not coagulated.
KIENBÖCK'S DISEASE IN SYSTEMIC LUPUS ERYTHEMATOSUS
Authors: Taniguchi Y. , Tamaki T. , Yoshida M.
Published: February 2003

We report two cases of Kienböck's disease associated with systemic lupus erythematosus SLE. The characteristics of these cases associated with SLE differed from those previously reported for Kienböck's disease. Corticosteroid may be a cause of Kienböck's disease in SLE.
PERCUTANEOUS CANNULATED SCREW FIXATION OF ACUTE SCAPHOID FRACTURES
Authors: Wu W.-C.
Published: February 2003

Percutaneous cannulated screw fixation (PCSF) of acute scaphoid fractures has been shown to consistently produce good results. It is less invasive and avoids damage to the radiocarpal ligaments. The scar is good. The procedure could be performed under Bier's block anaesthesia. No cast is required after the operation and the range of wrist motion is regained early. Most recently reported series achieved more than 95% primary radiological fracture union. The functional results were good. The surgical technique of PCSF is described in detail and special tricks for difficult problems are highlighted.
THE RADIOLOGICAL APPEARANCE OF RECURRENT PHALANGEAL SARCOIDOSIS
Authors: Kelly John L. , O'Shaughnessy Michael , O'Connor Thomas P. F.
Published: February 2003

Sarcoidosis of the phalanx is rare and is usually associated with severe systemic disease. We present a patient with recurrent phalangeal sarcoidosis and new evidence of a changing radiological pattern. The clinical presentation and outcome is discussed. High dose steroid treatment and careful long-term follow-up is recommended.
SPLINTING FOR PERIPHERAL NERVE INJURY IN UPPER LIMB
Authors: Chan Rebecca K. Y.
Published: February 2003

The prognosis and speed of peripheral nerve recovery depend very much on the level of injury, severity of injury, the surgical intervention and the subsequent rehabilitative process. Many high level injuries may take years or months for the affected peripheral nerve to recover. Prolonged muscle imbalance causes joint contractures and over-stretching of denervated muscles. Without proper care, hand function recovery may be limited even the nerve regenerated afterwards.

During the nerve regeneration period, splinting is one of the most useful modality to minimise deformities, prevent joint contractures and substitute loss motor control. Proper splinting encourages early use of the injured hand in daily activities. There are different types of splinting design for median nerve palsy, ulnar nerve palsy and radial nerve palsy. Dynamic splinting techniques are frequently employed to allow early prehension activities. Other therapeutic techniques, including pressure garment and sensory re-education are useful to enhance better functional return after nerve repair.
EVIDENCE-BASED PRACTICE IN SPLINTING THE INJURED HAND
Authors: Li-Tsang Cecilia W. P. , Chu Mary M. L.
Published: February 2003

Evidence-based medicine has been practised in the early 1990s in the Western countries and its model has aroused interests in the Asian countries including Hong Kong in the late 1990s. The need for evidence-based practice was called upon by Sackett and his colleagues14–16mainly because of the exponential growth of new evidence of treatment effectiveness. There is a great demand for clinicians to search for the best evidence and to incorporate into the daily practice so as to ensure the best quality and standard of treatment. This paper is to review the development and process of evidence-based practice in the area of hand splinting for our local clinicians. Some major problems were identified in the delivery of clinical evidence-based practice, and suggestions have been made to overcome these problems with a view in supporting its model in the local clinical field.
APPLICATION OF SPLINTING IN HAND REHABILITATION: A REFLECTION OF LOCAL PRACTICE
Authors: Li-Tsang Cecilia W. P.
Published: February 2003

Occupational therapists in Hong Kong have been very active in the management of patients with traumatic hand injuries due to industrial accidents. Splints have been prescribed as an adjunct to the exercise programme in rehabilitation. Other than the conventional thermoplastic splinting materials, metal hinges, coils and plastic strapping were used in splinting. The ultimate goal is to maximise the hand functions such that these workers could resume their work roles.
Early Carotid Atherosclerosis and Family History of Vascular Disease
Authors: Jerrard-Dunne Paula , Markus Hugh S. , Steckel Donata A. , Buehler Alexandra , von Kegler Stefan , Sitzer Matthias
Published: February 2003

Objective—

Carotid artery intima-media thickness (IMT) is an intermediate phenotype for atherosclerosis. In a community population (n=5400), we determined whether a parental history of myocardial infarction (MI) or stroke is associated with increased IMT and whether associations differ at specific sites in the carotid arterial tree.

Methods and Results—

Using regression modeling, the proportion of IMT that remains unexplained after controlling for vascular risk factors was determined. A parental history of stroke was associated with both increased common carotid artery (CCA) and increased internal carotid artery (ICA)-IMT, but in young individuals (≤60 years of age), the association was stronger with ICA-IMT, with an odds ratio (95% CI) for ICA-IMT in the highest quartile of 2.31 (1.67 to 3.21),
P
<0.001, compared with 1.53 (1.07 to 2.20),
P
=0.019, for CCA-IMT. In contrast, a parental history of MI was associated with increased CCA-IMT both overall and in young individuals but not with ICA-IMT, with an odds ratio (95% CI) for increased CCA-IMT of 2.51 (1.94 to 3.25),
P
<0.001, compared with 1.03 (0.78 to 1.35),
P
=0.861, for ICA-IMT.

Conclusions—

IMT has a significant familial component that is independent of conventional risk factors. Associations for stroke and MI differ at specific sites in the carotid arterial tree. Although commonly used aggregate CCA/ICA-IMT measures may be appropriate for candidate gene studies investigating stroke risk, these results suggest that CCA-IMT alone may be a better marker for MI risk.
Automatic Summarization of Open-Domain Multiparty Dialogues in Diverse Genres
Authors: Zechner Klaus
Published: February 2003

Automatic summarization of open-domain spoken dialogues is a relatively new research area. This article introduces the task and the challenges involved and motivates and presents an approach for obtaining automatic-extract summaries for human transcripts of multiparty dialogues of four different genres, without any restriction on domain.

We address the following issues, which are intrinsic to spoken-dialogue summarization and typically can be ignored when summarizing written text such as news wire data: (1) detection and removal of speech disfluencies; (2) detection and insertion of sentence boundaries; and (3) detection and linking of cross-speaker information units (question-answer pairs).

A system evaluation is performed using a corpus of 23 dialogue excerpts with an average duration of about 10 minutes, comprising 80 topical segments and about 47,000 words total. The corpus was manually annotated for relevant text spans by six human annotators. The global evaluation shows that for the two more informal genres, our summarization system using dialogue-specific components significantly outperforms two baselines: (1) a maximum-marginal-relevance ranking algorithm using TF*IDF term weighting, and (2) a LEAD baseline that extracts the first n words from a text.
Efficiently Computed Lexical Chains as an Intermediate Representation for Automatic Text Summarization
Authors: Silber H. Gregory , McCoy Kathleen F.
Published: February 2003

While automatic text summarization is an area that has received a great deal of attention in recent research, the problem of efficiency in this task has not been frequently addressed. When the size and quantity of documents available on the Internet and from other sources are considered, the need for a highly efficient tool that produces usable summaries is clear. We present a linear-time algorithm for lexical chain computation. The algorithm makes lexical chains a computationally feasible candidate as an intermediate representation for automatic text summarization. A method for evaluating lexical chains as an intermediate step in summarization is also presented and carried out. Such an evaluation was heretofore not possible because of the computational complexity of previous lexical chains algorithms.
Using Hidden Markov Modeling to Decompose Human-Written Summaries
Authors: Jing Hongyan
Published: February 2003

Professional summarizers often reuse original documents to generate summaries. The task of summary sentence decomposition is to deduce whether a summary sentence is constructed by reusing the original text and to identify reused phrases. Specifically, the decomposition program needs to answer three questions for a given summary sentence: (1) Is this summary sentence constructed by reusing the text in the original document? (2) If so, what phrases in the sentence come from the original document? and (3) From where in the document do the phrases come? Solving the decomposition problem can lead to better text generation techniques for summarization. Decomposition can also provide large training and testing corpora for extraction-based summarizers. We propose a hidden Markov model solution to the decomposition problem. Evaluations show that the proposed algorithm performs well.