bluuebunny/crossref_metadata_2025 huggingface dataset:
Mg
Zn
O
∕
Al
Ga
N
heterostructure light-emitting diodes
Authors: Osinsky A. , Dong J. W. , Kauser M. Z. , Hertog B. , Dabiran A. M. , Chow P. P. , Pearton S. J. , Lopatiuk O. , Chernyak L.
Published: November 2004

We report on p–n junction light-emitting diodes fabricated from MgZnO∕ZnO∕AlGaN∕GaN triple heterostructures. Energy band diagrams of the light-emitting diode structure incorporating piezoelectric and spontaneous polarization fields were simulated, revealing a strong hole confinement near the n-ZnO∕p-AlGaN interface with a hole sheet density as large as 1.82×1013cm−2 for strained structures. The measured current–voltage (IV) characteristics of the triple heterostructure p–n junctions have rectifying characteristics with a turn-on voltage of ∼3.2V. Electron-beam-induced current measurements confirmed the presence of a p–n junction located at the n-ZnO∕p-AlGaN interface. Strong optical emission was observed at ∼390nm as expected for excitonic optical transitions in these structures. Experimental spectral dependence of the photocurrent confirmed the excitonic origin of the optical transition at 390nm. Light emission was measured up to 650K, providing additional confirmation of the excitonic nature of the optical transitions in the devices.
Defect passivation in multicrystalline silicon for solar cells
Authors: Tarasov I. , Ostapenko S. , Nakayashiki K. , Rohatgi A.
Published: November 2004

We report on the effect of hydrogen passivation in ribbon multicrystalline silicon (mc-Si) wafers from SiNx:H anti-reflecting layer using simultaneous rapid thermal annealing of Al back-contact and SiNx anti-reflection coating on the front (RTP-Al∕SiNx). Scanning room-temperature photoluminescence spectroscopy revealed a strong inhomogeneity in the increase of minority carrier lifetime caused by the hydrogen defect passivation in mc-Si. We present experimental evidence that RTP-Al∕SiNx processing leads to strong lifetime enhancement caused by hydrogen defect passivation in low-lifetime regions of mc-Si wafers. Additional details on the hydrogenation mechanism are revealed in a course of the dehydrogenation study. Hydrogen out-diffusion shows a different rate or activation energy between high and low lifetime regions of the wafers.
Plasma damage-free deposition of Al cathode on organic light-emitting devices by using mirror shape target sputtering
Authors: Kim Han-Ki , Kim D.-G. , Lee K.-S. , Huh M.-S. , Jeong S. H. , Kim K. I. , Kim H. , Han D. W. , Kwon J. H.
Published: November 2004

We report on the fabrication of plasma damage-free organic light-emitting devices (OLEDs) by using a mirror shape target sputtering (MSTS) technique. It is shown that OLEDs with Al cathode deposited by the MSTS show much lower leakage current (1×10−5mA∕cm2) at reverse bias of −6V, compared to that (1×10−1–∼10−2mA∕cm2 at −6V) of OLEDs with Al cathodes grown by conventional dc magnetron sputtering. This indicates that there is no plasma damage, which is caused by the bombardment of energetic particles. This suggests that MSTS could be a useful plasma damage-free and low-temperature deposition technique for both top- and bottom-emitting OLEDs and flexible displays.
Effect of source/drain undercut on the performance of pentacene thin-film transistors on plastic
Authors: Kim Sung Hwan , Choi Hye Young , Jang Jin
Published: November 2004

We studied the electrical properties of bottom contact pentacene thin-film transistors (TFTs) on plastic with and without source/drain undercut. The undercut depends on the Cr thickness in Au∕Cr source/drain electrodes, where Au is used for the ohmic contact with pentacene, and the Cr is to enhance the adhesion of Au to the cross-linked poly-4-vinyphenol gate insulator. The undercut can be removed by reducing the Cr thickness less than 5nm. The TFTs with and without undercut exhibited the field-effect mobility in the saturation region of 0.96 and 1.3cm2∕Vs, respectively, but in the linear region the field-effect mobility of the TFT with source/drain undercut is ∼1∕9 that of the organic TFT without undercut.
Avalanche spin-valve transistor
Authors: Russell K. J. , Appelbaum Ian , Yi Wei , Monsma D. J. , Capasso F. , Marcus C. M. , Narayanamurti V. , Hanson M. P. , Gossard A. C.
Published: November 2004

A spin-valve transistor with a GaAs∕AlGaAs avalanche-multiplying collector is demonstrated with >1000% magnetocurrent variation and ≈35× amplification of the collector current. The intrinsic amplification of the magnetic-field sensitive collector current should allow fabrication of spin-valve transistors with high gain in a variety of materials.
Bend design for the low-group-velocity mode in photonic crystal-slab waveguides
Authors: Moll N. , Bona G.-L.
Published: November 2004

We investigated bends for photonic crystals with triangular arrays of holes theoretically by employing two-dimensional band-structure and transmission calculations. We find that the guided mode of the bend is frequency-shifted compared with that of a straight waveguide. Decreasing the size of the holes in the immediate vicinity of the bend shifts the frequency of the mode back. These optimized bends can guide light in the frequency region of very low group velocities around corners.
Suspension extraction through an opening before clogging
Authors: Goldsztein Guillermo H. , Santamarina Juan C.
Published: November 2004

Fluids with particles in suspension can be extracted through an orifice until particles bridge across the opening and clog it. We derive and study a mathematical model to predict the volume of fluid that can be extracted before clogging. Numerical simulations and closed-form upper and lower bound solutions show the dependency of the expected extracted volume on the volume fraction of particles in suspension and the relative particle-to-orifice size. These results are the first step toward a comprehensive understanding of the physical mechanisms leading to filter clogging with relevance to geomaterials, biomaterials, and industrial applications.
Surfactant-assisted synthesis of Tb(III)-doped cerium phosphate single-crystalline nanorods with enhanced green emission
Authors: Bu Wenbo , Chen Hangrong , Hua Zile , Liu Zhicheng , Huang Weimin , Zhang Lingxia , Shi Jianlin
Published: November 2004

Strong green emission has been obtained for Tb(III)-doped cerium phosphate single-crystalline nanorods synthesized via a facile, Pluronic P123 (EO20PO70EO20Mav=5800, Aldrich)-assisted, hydrothermal method. The surfactant Pluronic P123 was found to play a crucial role in the enhanced photoluminescence emission as compared with the same material but synthesized without the surfactant. The smooth surface, well-defined facets, single crystalline feature, uniform morphologies, and especially very narrow size distributions (10–12nm) of the Tb(III)-doped cerium phosphate single-crystalline nanorods are considered to be responsible for the strong photoluminescence emission.
Atom lithography of Fe
Authors: te Sligte E. , Smeets B. , van der Stam K. M. R. , Herfst R. W. , van der Straten P. , Beijerinck H. C. W. , van Leeuwen K. A. H.
Published: November 2004

Direct write atom lithography is a technique in which nearly resonant light is used to pattern an atom beam. Nanostructures are formed when the patterned beam falls onto a substrate. We have applied this lithography scheme to a ferromagnetic element, using a 372nm laser light standing wave to pattern a beam of iron atoms. In this proof-of-principle experiment, we have deposited a grid of 50-nm-wide lines 186nm apart. These ultraregular, large-scale, ferromagnetic wire arrays may generate exciting new developments in the fields of spintronics and nanomagnetics.
Reduction of focus size in tightly focused linearly polarized beams
Authors: Martínez-Corral M. , Martínez-Cuenca R. , Escobar I. , Saavedra G.
Published: November 2004

The electromagnetic theory predicts that when a linearly polarized collimated field is focused by a high-angle focusing system, components perpendicular to the initial polarization are generated. The use of annular masks to reduce the area of the focal spot usually increases the magnitude of this phenomenon, known as depolarization. We present a class of masks, the three-ring masks, which are important because they narrow the central lobe of the focal intensity distribution without increasing the depolarization. This can be very useful in modern optical applications, such as confocal microscopy or multiphoton scanning microscopy.
Density of states determination from steady-state photocarrier grating measurements
Authors: Schmidt J. A. , Longeaud C.
Published: November 2004

We present a method to obtain the density of states (DOS) of photoconductive insulators based on steady-state photocarrier grating (SSPG) measurements. A simple expression—relating the DOS at the electron quasi-Fermi level to measurable quantities—is deduced by performing suitable approximations from the analytical solution of the generalized equations that describe the SSPG experiment. The validity of the approximations and the applicability of the final expression are verified from numerical simulations of the process. The usefulness of the method is demonstrated by performing measurements on a standard hydrogenated amorphous silicon sample.
Femtosecond coherent anti-Stokes Raman scattering spectroscopy using supercontinuum generated from a photonic crystal fiber
Authors: Kano Hideaki , Hamaguchi Hiro-o
Published: November 2004

Femtosecond time-resolved coherent anti-Stokes Raman scattering (CARS) spectroscopy is demonstrated using a Ti:Sapphire oscillator and a photonic crystal fiber. A spectrally dispersed CARS signal of cyclohexane exhibits well-defined beats with a period of 430fs, which agrees well with a frequency difference between the symmetric and antisymmetric CH2-stretching vibrational modes.
Distributed feedback sol-gel zirconia channel waveguide lasers
Authors: Chen Fei , Wang Jun , Ye Chao , Lo Dennis , Zhu Xiao-lei
Published: November 2004

We fabricated dye-doped zirconia channel waveguides using wet or dry etching of quartz substrates followed by sol-gel deposition of the Rhodamine 6G-doped zirconia in the channel. Distributed feedback laser action was generated in the channel waveguides by crossing two nanosecond laser beams at 532nm. Maintaining the depth of the active zirconia layer at 3μm, narrow linewidth lasing was achieved for rectangular channel waveguides with widths at 5, 6.5, and 10μm. Wavelength tuning was achieved from 570to608nm. The output laser mode was identified as the fundamental E11x mode. The dispersion behavior of the laser output was checked by comparing experiments with the predictions of Marcatili’s theory.
Experimental evidence for the presence of segregation and relaxation gettering of iron in polycrystalline silicon layers on silicon
Authors: Istratov A. A. , Huber W. , Weber E. R.
Published: November 2004

Experimental evidence is provided that gettering of iron by polycrystalline silicon (polysilicon) is driven by a combination of two gettering mechanisms, segregation and relaxation. The segregation coefficient of iron in polysilicon in samples annealed at temperatures between 1020 and 1175°C varied from approximately 16 to 2. The efficiency of relaxation gettering by polysilicon was characterized using Ham’s model of diffusion-limited gettering. The product nr0 for the 11-μm-thick polysilicon layer was estimated as 106cm−2.
Structural and optical properties of GaN1−xAsx grown by metalorganic chemical vapor deposition
Authors: Tsuda Yuhzoh , Mouri Hirokazu , Yuasa Takayuki , Taneya Mototaka
Published: November 2004

GaN-based GaN1−xAsx alloys, x⩽0.043, were grown by metalorganic chemical vapor deposition. The results of high-resolution x-ray diffraction measurements indicated that no phase separation was observed over a range of up to x=0.043 and both the lattice constants c and a increased with an increase in arsenic composition. In cathodoluminescence measurements, the GaN1−xAsx showed a large band gap bowing parameter of 22.1eV. Furthermore, we have experimentally revealed that the valence band offset for the GaN1−xAsx∕GaN is very large, and we have proposed the band gap energy diagram of GaN1−xAsx utilizing an arsenic deep donor level.
The 1.54-μm photoluminescence from an (Er, Ge) co-doped SiO2 film deposited on Si by rf magnetron sputtering
Authors: Heng C. L. , Finstad T. G. , Storås P. , Li Y. J. , Gunnæs A. E. , Nilsen O.
Published: November 2004

In this work, we report on quite strong 1.54-μm photoluminescence (PL) from an (Er, Ge) co-doped SiO2 film deposited by rf magnetron sputtering. The PL intensity reaches a maximum value after the film is annealed at 700°C for 30min in N2. High-resolution transmission electron microscopy observation, together with energy dispersive x-ray spectroscopy analysis, indicates that amorphous Ge-rich nanoclusters precipitate in the film after 700°C annealing. X-ray diffraction shows the presence of Ge nanocrystals after 900°C annealing, and increasing Ge nanocrystal size with increasing annealing temperature up to 1100°C. The results suggest that the amorphous Ge-rich nanoclusters are more effective than Ge nanocrystals in exciting the Er3+ PL.
On the apparently anomalous response of porous silicon to nitrogen dioxide
Authors: Amato G. , Boarino L. , Bellotti F.
Published: November 2004

Recent publications reported a large increase of conductivity in mesoporous silicon exposed to traces of nitrogen dioxide. The phenomenon has been studied from theoretical and experimental points of view. Even if a complete comprehension has not been reached yet, it seems clear that the simple increase in the number of mobile carriers inside the material cannot fully account for the experimental evidence; an increase of their mobility must provide a more robust contribution. The fresh observation of an opposite effect occurring in sufficiently thin mesoporous samples is then surprising. The present letter shows that such an apparently contradictory result can be explained in terms of the well-known theory of current injection in insulators.
GaAs
Esaki junctions with autocompensated impurities in the n side by metalorganic chemical vapor deposition
Authors: Zhang Jizhi , Lau Kei May
Published: November 2004

GaAs Esaki junctions were grown at normal growth temperatures above 550 °C by low pressure metalorganic chemical vapor deposition. The n sides of these junctions were heavily doped with silane into the regime that impurities were autocompensated. Consequently, zero-bias tunnel resistance was significantly reduced. We obtained a low zero-bias specific tunnel resistance of 9.6×10−5Ωcm2 with an optimized silane flow rate.
Near Surface Residual Stress Determination of Laser Shock Peening by Neutron Diffraction
Authors: Evans A.D. , King A. , Pirling T. , Bruno G. , Withers P.J.
Published: November 2004

The study of the residual stress fields generated by the advanced surface treatment laser shock peening (LSP) requires a technique that can measure from the bulk to the surface of a material. The application of primary and secondary collimator optics for the monochromatic neutron beam, and minor experimental corrections allow very near surface measurements without the associated errors of the “surface effect”. The measurements reveal that LSP generates compressive in-plane residual stresses to a depth of 1 mm in Ti-6Al-4V plate. Maximum compression is located at the surface (−800 MPa) and the balancing tensile residual stresses (max. 200 MPa) are located 2 mm beneath the surface. The use of a secondary radial collimator allows the determination of diffraction peak width depth profiles, indicating plastic deformation caused by LSP of 1–2 mm.
Residual Stress Analyses Based on Neutron Diffraction in Double-V Butt Welded Steel Plates
Authors: Ohms C. , Hornak P. , Wimpory R. , Youtsos A.G.
Published: November 2004

Residual stress measurements on a double-V butt weld joining two plates of nominally identical stainless steel have been performed using two neutron diffractometers. Sections of 270, 30 and 4 mm length cut from an original welded plate of 2.5 m length and 400 mm width were investigated using the large component neutron diffraction facility (LCNDF), at beam tube HB4, and the recently recommissioned combined powder and stress diffractometer, at beam tube HB5, at the high flux reactor (HFR) of the European Commission in Petten. Strains and stresses have been mapped in specimens of all three sizes testing the weld longitudinal, welding transverse and plate normal directions. The test results show a significant stress relaxation due to specimen cutting only in the direction normal to the cuts, e.g. from 270 to 30 mm length reduced the weld longitudinal stresses by 50%. In the other two in-plane directions the stresses were found largely unaltered.
The Residual-stress Diffractometer for the Australian Replacement Research Reactor
Authors: Kirstein O.
Published: November 2004

The new Australian replacement research reactor will become operational in 2006. Amongst the first suite of eight instruments accessible to international users is a diffractometer dedicated to stress-related problems of the scientific community and industry. The basic features and criteria of the instrumental design are presented. The study shows that the instrument will belong to the best instruments world-wide especially designed for these kinds of problems.
The Use of Combs for Evaluation of Strain-free References for Residual Strain Measurements by Neutron and Synchrotron X-ray Diffraction
Authors: Hughes D.J. , James M.N. , Hattingh D.G. , Webster P.J.
Published: November 2004

The measurement of residual strain using diffraction techniques relies on the determination of a change in lattice parameter relative to a reference or “strain-free” lattice parameter. Therefore, obtaining a relevant reference lattice parameter is perhaps the most important part of any diffraction-based strain experiment. This is particularly important in samples where one may expect a changing reference, for example in a weld where microstructure may vary due to heating. One method of determining appropriate references is the use of “combs” machined from the sample. The teeth should essentially be macro-strain relieved and reveal information about microstructural and intergranular strain variations. It is shown that there is often significant variation in measured diffraction angles along the length of a comb and that the most reliable measurements for strain-free reference are at the ends of the teeth. A study is presented of the application of strain-free combs in friction-stir welded plates.
A maternity hospital-based infant car-restraint loan scheme: Public health and economic evaluation of an intervention for the reduction of road traffic injuries
Authors: Kedikoglou Simeon , Belechri Maria , Dedoukou Xanthi , Spyridopoulos Themis , Alexe Delia-Marina , Pappa Evanthia , Stamou Asimoula , Petridou Eleni
Published: November 2004

Aims: The results of an infant car-restraint loan scheme and evaluate its cost-effectiveness are presented. Methods: The intervention programme was initiated in 1996. Car-restraints, donated by manufacturers, were lent for a six-month period to eligible prospective parents for a modest fee. Specially trained health visitors performed in-person interviews with the participating parents. The data were collected and recorded on a pre-coded questionnaire. Cross-tabulations and multiple logistic regression were performed to analyse the data. Subsequent purchase of a next-stage car restraint, suitable for older children (up to four years of age) was considered as a proxy measure of the success of the programme. This information, along with the detailed operational and financial data collected during the implementation phase of the programme, was used to develop a model to assess the cost-effectiveness of a countrywide intervention. Results: During a two-year period 188 families participated in a survey. On return of the infant car restraint, 92% of the participants reported proper use of the device and 82% had already purchased the second-stage car restraint. Parental age, gender, or educational status was not predictive of positive parental road safety practices for the newly born, whereas history of parental seat-belt use — as a proxy of personal road safety behaviour — was positively correlated with the likelihood of purchasing a second-stage car-restraint device. The cost-effectiveness ratio varies between 418.00 and 3,225.00 per life-year saved, depending on whether the modest administrative fee is considered. Conclusions: On the basis of plausible assumptions, a loan programme of infant car-restraints was shown to be particularly cost effective.
Balancing Akt with S6K
Authors: Manning Brendan D.
Published: November 2004

Proper regulation of the phosphoinositide 3-kinase–Akt pathway is critical for the prevention of both insulin resistance and tumorigenesis. Many recent studies have characterized a negative feedback loop in which components of one downstream branch of this pathway, composed of the mammalian target of rapamycin and ribosomal S6 kinase, block further activation of the pathway through inhibition of insulin receptor substrate function. These findings form a novel basis for improved understanding of the pathophysiology of metabolic diseases (e.g., diabetes and obesity), tumor syndromes (e.g., tuberous sclerosis complex and Peutz-Jegher's syndrome), and human cancers.
Heritage property, tourism and the UK Disability Discrimination Act
Authors: Goodall Brian , Pottinger Gaye , Dixon Tim , Russell Henry
Published: November 2004

Heritage tourism depends on a physical resource based primarily on listed buildings and scheduled monuments. Visiting or staying in a historic building provides a rich tourism experience, but historic environments date from eras when access for disabled people was not a consideration. Current UK Government policy now promotes social inclusion via an array of equal opportunities, widening participation and anti‐discrimination policies. Historic environments enjoy considerable legislative protection from adverse change, but now need to balance conservation with public access for all. This paper discusses the basis of research being undertaken by The College of Estate Management funded by the Mercers Company of London and the Harold Samuel Trust. It assesses how the 1995 Disability Discrimination Act has changed the legal obligations of owners/operators in managing access to listed buildings in tourism use. It also examines the key stakeholders and power structures in the management of historic buildings and distinguishes other important players in the management process.
Stakeholders' perceptions of the DCF method in hotel valuations
Authors: Verginis Constantinos S. , Stephen Taylor J.
Published: November 2004

The main stakeholder of any valuation is the commissioning party and the outcome of the valuation process will determine for the commissioning party the value of the asset. The second key stakeholder is the valuer. Often, however, there is third stakeholder group, the lending institution. Lending institutions often provide financing to the buyer and the financing decision is often based on the hotel's valuation. Based on a questionnaire survey of hotel valuation stakeholders this study reports the findings as to the perceived suitability of the discounted cash flow (DCF) valuations in respect of hotel property. The findings reported here suggest that the majority of respondents supported the view that the DCF method was the most suitable method in relation to hotel valuations. However, there are indications that the recommended practice of the need for using supporting valuation approaches might not be widely observed or understood. In addition, there was a view among a significant minority of respondents that the DCF method was only applicable for those properties operating at the higher market levels.
Approximation of multiple integrals by simple integrals involving periodic functions
Authors: Benabidallah A. , Cherruault Y. , Mora G.
Published: November 2004

In this paper, we consider problems of numerical integration of fast oscillatory functions of one variable, obtained by using α‐dense curves and approximating multiple integrals. Using first, periodic and regular α‐dense curves we propose a trapezoidal formula for calculating the periodic integrand obtained. Then, we consider the simple integrals as integrals with weight. We propose a method to evaluate the moments of the weight function. This allows us to build a recurrent formula for the orthogonal polynomials family and to use a Gaussian rule to estimate the simple integral. Finally, we adapt the Filon's method, consisting in evaluating the Fourier coefficients of a function, to the oscillatory integrand obtained by using reducing transformations.
The purpose of second‐order cybernetics
Authors: Glanville Ranulph
Published: November 2004

In this paper, the origins of second‐order Cybernetics are sketched, and are particularly identified with circularity: a quality that was at the basis of the studies that lead to the creation of the field of Cybernetics. The implications of the new analysis that second‐order Cybernetics (Cybernetics treated cybernetically: that is, Cybernetics when circularity is taken seriously) gives rise to are considered in terms of the two qualities that Wiener gave to Cybernetics in his eponymous book – control and communication. Finally, the analysis is applied to that other proto‐cybernetic concept, purpose. It is shown that (and in consequence how) the notion of goal and purpose must be radically reconsidered in second‐order Cybernetic systems.
Self‐organisation as quality control in inquiry
Authors: de Zeeuw Gerard
Published: November 2004

Knowledge is defined as the result of successful attempts to transfer expected effort in the future to effort spent in the present. The less effort remains to be spent in the future, the more knowledge is exhaustive and complete. It is shown that some efforts remain necessary in the future for accidental reasons, e.g. to correct mistakes, to estimate parameters, to act. Some efforts will also be required for fundamental reasons. They are needed to compensate as and when testing for exhaustiveness proves ineffective. It is argued that the need for such additional effort may be met by starting collectives as a form of pre‐containment. Such collectives may include non‐ordered experiences. They will maintain themselves by striving to serve as equivalents to knowledge. They help in two ways: they indicate what is needed to create which knowledge. The design of collectives serving as knowledge is linked to second‐order cybernetics.
Axioms from interactions of actors theory
Authors: Green Nick
Published: November 2004

While working with clients in the last years of his life, Gordon Pask produced an axiomatic scheme for his Interactions of Actors Theory which is a development of his well known Conversation Theory. These axioms are interpretable as a general theory of self‐organisation and are discussed as characteristic of field concurrence and as part of the second‐order cybernetics canon. An application to population density is reported supported by both kinematic and kinetic simulation. Implications for cardiovascular anti‐coagulation therapy and planetary evolution are discussed.
Finite volume approach for solving multiphase flows in vertical pneumatic dryers
Authors: Skuratovsky I. , Levy A.
Published: November 2004

In the present study, a finite volume approach for solving two‐dimensional, two‐fluids flows with heat and mass transfer was developed for predicting the flow of particulate materials through pneumatic dryer. The model was solved for a two‐dimensional steady‐state condition and considering axial and radial profiles for the flow variables. A two‐stage drying process was implemented. The numerical procedure includes discretization of calculation domain into torus‐shaped final volumes, solving the gas phase conservation equations by a modified semi‐implicit method for pressure‐linked equations algorithm, and the conservation equations of particulate phase were solved by the explicit forward difference algorithm. The mass momentum and energy coupling between the phases were considered by principles of the Interphase slip algorithm. In order to validate the theoretical and the numerical models, the developed models were applied to simulate the drying process of wet PVC particles in a large‐scale pneumatic dryer and to the drying process of wet sand in a laboratory‐scale pneumatic dryer. The predictions of the numerical simulations were compared successfully with the results of independent numerical and experimental investigations. Following the models validation, the two‐dimensional distributions of the flow characteristics were examined.
Jet impingement onto a conical cavity with elevated wall temperature
Authors: Yilbas B.S. , Shuja S.Z. , Budair M.O.
Published: November 2004

Gas jet assisting process finds wide application in industry due to its ability to alter the heat transfer characteristics of the region subjected to jet assisted processing. In the present study, jet impingement onto a cavity with elevated wall temperature is considered. The flow and heat transfer equations are solved numerically using a control volume approach. Reynolds Stress Turbulence Model is employed to account for the turbulence. The simulations are repeated for four cavity depths and two gas jet velocities. It is found that the stagnation zone moves slightly further into the cavity with increasing cavity depth. The flow generated behind the stagnation zone in the cavity influences the heat transfer characteristics in this region, particularly for the cavities with relatively large depth.
Does promoting bicycle‐helmet wearing reduce childhood head injuries?
Authors: Farley Céline , Vaez Marjan , Laflamme Lucie
Published: November 2004

The objectives of the study are to assess the impact of a community‐based bicycle‐helmet program aimed at children aged 5–12 years (about 140,000). A quasi‐experimental design, including a control group, was used. Sex‐ and age‐group‐based changes in the risk of bicycle‐related head injury leading to hospitalisation were measured, using rate ratios. Compared with the pre‐program period, significant risk reductions were observed during the post‐program period among both boys (RR = 0.56, 95 per cent CI = 0.40, 0.77) and girls (RR = 0.52, 95 per cent CI = 0.33, 0.82), and among both younger (RR = 0.46, 95 per cent CI = 0.31, 0.68) and older (RR = 0.63, 95 per cent CI = 0.44, 0.89) children. A significant reduction was also observable during the program phase among the groups most at risk, i.e. boys (RR = 0.94, 95 per cent CI = 0.66, 1.35) and younger children (RR = 1.07, 95 per cent CI = 0.70, 1.63). The population‐based educational program significantly decreased the risk of head injuries among boys and girls despite observable differences in the voluntary adoption rate of bicycle‐helmet wearing. The impact was more pronounced among younger children.
Are former “third‐culture kids” the ideal business expatriates?
Authors: Lam Hon , Selmer Jan
Published: November 2004

Third‐culture kids (TCKs) are adolescents who have lived at least one of their formative years in another country. This study compares survey data collected from British TCKs who were currently living in Hong Kong with those of their adolescent peers living in the UK and Hong Kong. The results unequivocally suggest that TCKs’ perception of being international and their characteristics are different than that of their adolescent peers in the host and home country. More than the other adolescents, TCKs indicated that international experience, parental and institutional education, a second language, neutrality, open‐mindedness and flexibility, attitudes towards other systems and cultures, respect for others, tolerance of others’ behaviour and views, all contributed to the perception of being international. Similarly, TCKs had distinctive characteristics in terms of stronger family relationships, enjoying travelling to foreign places, acceptance of foreign languages, acceptance of cultural differences, and future orientation. Implications for international firms of these fundamental findings are discussed in detail.
A model for learning in working life
Authors: Illeris Knud
Published: November 2004

The aim of this article is to develop a holistic model that shows the basic elements of workplace learning and their mutual connections. This is done by adjusting and combining two models that have already been worked out formerly by members of the consortium: a model dealing with the workplace as a learning space, and a general model of the learning process. The most important features of the new model are its distinction between the social and the individual levels of learning, and its pointing to the overlap between the working practice of the organisation and the work identities of the employees as the central area for important workplace learning. Concludes by discussing the purposes to which this model can be put.
Challenges for work‐integrated e‐learning
Authors: Svensson Lars
Published: November 2004

In an action‐oriented research project, the Laboratorium for Interaction Technology at the University of Trolhättan Uddevalla, together with six of Sweden's county administrations, is aiming at developing an academy for all scholastic education and training hosted by the county administrations. The point of departure for the paper is a classification of the educational needs reported by national special interest groups covering a wide range of the fields of expertise that characterises work and organisation of the 21 county administrations of Sweden. The demanded courses can be classified with respect to two orthogonal dichotomies: inter‐ vs intra‐disciplinary scope of content and educational objectives being focused on adapting to, or changing a existing practice. The paper goes on to present and discuss three major challenges for work‐integrated e‐learning: the expert dilemma; situatedness vs decontextualisation of work practice; and the aspect of planning for the unknown. It is argued that addressing these obstacles calls for techno‐pedagogical designs that are inspired and influenced by a number of scholastic traditions ranging from traditional classroom education and case methodology to seminars and the learning circles of liberal adult education.
Managing knowledge creation and sharing – scenarios and dynamic capabilities in inter‐industrial knowledge networks
Authors: Bergman Jukka , Jantunen Ari , Saksa Juha‐Matti
Published: November 2004

Organizations are finding it more and more difficult to stay in balance with the pace of change. The continuous rise of business opportunities and the increase in global competition demands proactive knowledge management tools, new capabilities and an ability to renew and reconfigure existing capabilities. This paper presents a framework of the scenario process as a management tool for creating and sharing future‐oriented tacit knowledge in knowledge networks and describes how dynamic capabilities can be developed in view of future scenarios. The theoretical framework was tested in an inter‐industrial research project resulting in very promising findings about managing tacit, future‐oriented knowledge.
E‐relationship marketing: changes in traditional marketing as an outcome of electronic customer relationship management
Authors: Sue Scullin Shannon , Fjermestad Jerry , Romano Nicholas C.
Published: November 2004

Marketing concepts and definitions have remained relatively unchanged until recently. Electronic customer relationship management (eCRM) has forced marketing managers to reevaluate how, when and to what extent they interact with their customers. This paper is focused on the role of specific marketing concepts and how eCRM has enhanced or altered each concept. Every topic discussed is illustrated with current business examples. Several examples from the business trade press are used to illustrate the success an organization can achieve when using eCRM to enhance marketing skills.
NOISE-ENHANCED PERFORMANCE IN A CORTICAL ASSOCIATIVE MEMORY MODEL
Authors: LILJENSTRÖM H. , WU X.-B.
Published: November 2004

Spontaneous neuronal activity and synaptic noise are well-known phenomena, but their biological significance has not yet been assessed. Using a computer model of the olfactory cortex we show that such activity, expressed as temporal noise in the model, can reduce recall time in associative memory tasks. We investigate both additive and multiplicative noise, and find optimal noise levels for which the recall time reaches a minimum. In addition, we demonstrate that noise can induce state transitions, such that the system is pushed from one attractor state to another. For high enough noise levels the dynamics can change dramatically and, for example, switch from an oscillatory to a chaos-like behavior. We discuss these findings in light of their significance for neural information processing.
ENSEMBLE COMPETITIVE LEARNING NEURAL NETWORKS WITH REDUCED INPUT DIMENSION
Authors: KIM JONGWAN , AHN JESUNG , CHO SEONGWON
Published: November 2004

Conventional neural networks utilize all the dimensions of the original input patterns for training and classification. However, a particular attribute of the input patterns does not necessarily contribute to classification and may even cause misclassification in certain cases.

A new ensemble competitive learning method using the reduced input dimension is proposed. In contrast to the previous ensemble neural networks which adjust learning parameters, the proposed method takes advantage of the information in each dimension of the input patterns. Since the degree of contribution of each attribute to classification is not known beforehand, the different input data sets with one dimension reduced are presented to multiple neural networks. The classification information from each competitive learning neural network is then combined to make a final decision for classification.

In order to improve classification accuracy, the ambiguous output neurons are eliminated which cannot be assigned to any class after training. We use three consensus schemes to judge the classification using ensemble neural networks. The experimental results with remote sensing and speech data indicate the improved performance of the proposed method.
DYNAMICAL RECURRENT NEURAL NETWORKS — TOWARDS ENVIRONMENTAL TIME SERIES PREDICTION
Authors: AUSSEM ALEX , MURTAGH FIONN , SARAZIN MARC
Published: November 2004

Dynamical Recurrent Neural Networks (DRNN) (Aussem 1995a) are a class of fully recurrent networks obtained by modeling synapses as autoregressive filters. By virtue of their internal dynamic, these networks approximate the underlying law governing the time series by a system of nonlinear difference equations of internal variables. They therefore provide history-sensitive forecasts without having to be explicitly fed with external memory. The model is trained by a local and recursive error propagation algorithm called temporal-recurrent-backpropagation. The efficiency of the procedure benefits from the exponential decay of the gradient terms backpropagated through the adjoint network. We assess the predictive ability of the DRNN model with meteorological and astronomical time series recorded around the candidate observation sites for the future VLT telescope. The hope is that reliable environmental forecasts provided with the model will allow the modern telescopes to be preset, a few hours in advance, in the most suited instrumental mode. In this perspective, the model is first appraised on precipitation measurements with traditional nonlinear AR and ARMA techniques using feedforward networks. Then we tackle a complex problem, namely the prediction of astronomical seeing, known to be a very erratic time series. A fuzzy coding approach is used to reduce the complexity of the underlying laws governing the seeing. Then, a fuzzy correspondence analysis is carried out to explore the internal relationships in the data. Based on a carefully selected set of meteorological variables at the same time-point, a nonlinear multiple regression, termed nowcasting (Murtagh et al. 1993, 1995), is carried out on the fuzzily coded seeing records. The DRNN is shown to outperform the fuzzy k-nearest neighbors method.
LEARNING IN RECURRENT FINITE DIFFERENCE NETWORKS
Authors: TSUNG FU-SHENG , COTTRELL GARRISON W.
Published: November 2004

A recurrent learning algorithm based on a finite difference discretization of continuous equations for neural networks is derived. This algorithm has the simplicity of discrete algorithms while retaining some essential characteristics of the continuous equations. In discrete networks learning smooth oscillations is difficult if the period of oscillation is too large. The network either grossly distorts the waveforms or is unable to learn at all. We show how the finite difference formulation can explain and overcome this problem. Formulas for learning time constants and time delays in this framework are also presented.
CAN DETERMINISTIC PENALTY TERMS MODEL THE EFFECTS OF SYNAPTIC WEIGHT NOISE ON NETWORK FAULT-TOLERANCE?
Authors: EDWARDS PETER J. , MURRAY ALAN F.
Published: November 2004

This paper investigates fault tolerance in feedforward neural networks, for a realistic fault model based on analog hardware. In our previous work with synaptic weight noise26 we showed significant fault tolerance enhancement over standard training algorithms. We proposed that when introduced into training, weight noise distributes the network computation more evenly across the weights and thus enhances fault tolerance. Here we compare those results with an approximation to the mechanisms induced by stochastic weight noise, incorporated into training deterministically via penalty terms. The penalty terms are an approximation to weight saliency and therefore, in addition, we assess a number of other weight saliency measures and perform comparison experiments. The results show that the first term approximation is an incomplete model of weight noise in terms of fault tolerance. Also the error Hessian is shown to be the most accurate measure of weight saliency.
A CORRELATION SIGNIFICANCE LEARNING SCHEME FOR AUTO-ASSOCIATIVE MEMORIES
Authors: LEE DONQ-LIANG , WANG WEN-JUNE
Published: November 2004

A new concept called correlation significance for expanding the attraction regions around all the stored vectors (attractors) of an asynchronous auto-associative memory is introduced. Since the well known outer product rule adopts equally-weighted correlation matrix for the neuron connections, the attraction region around each attractor is not maximized. In order to maximize these attraction regions, we devise a rule that all the correlations between two different components of two different stored patterns should be unequally weighted. By this formalism, the connection matrix T of the asynchronous neural network is designed by using the gradient descent approach. Additionally, an exponential type error function is constructed such that the number of successfully stored vectors can be directly examined during the entire learning process. Finally, computer simulations demonstrate the efficiency and capability of this scheme.
ELECTRON WAVE FUNCTION IN THE FIELD OF ONE-DIMENSIONAL IRREGULAR LAYERED STRUCTURE
Authors: Zh. KHACHATRIAN A.
Published: November 2004

A method is proposed to find the wave function of an electron moving infinitely in the field of an arbitrary 1D layered structure with two different homogeneous semi-infinite boundaries. It is shown that in general the problem reduces to solution of a set of two linear recurrent equations. The proposed approach is discussed on a base of two cases: a structure of periodically placed identical rectangular potentials and a nonordered structure with certain distortion of periodicity and potential identity.
LIE SERIES TECHNIQUE, LIMIT CYCLE SYSTEMS AND DYNAMICAL INTEGRATION
Authors: STEEB WILLI-HANS
Published: November 2004

The Lie series technique is applied to solve a class of nonlinear differential equations. We show that it includes also the dynamical integration technique. In particular systems with limit cycle behavior are studied. Differential equations with chaotic behavior are also considered with this technique.
THE BRST CHARGE FOR THE $\hat D (2, 1; \alpha)$ NONLINEAR QUASI-SUPERCONFORMAL ALGEBRA
Authors: KETOV SERGEI V.
Published: November 2004

The quantum BRST charge for the most general, two-dimensional, nonlinear, N = 4 quasi-superconformal algebra [Formula: see text], whose linearization is the so-called 'large' N = 4 superconformal algebra, is constructed. The [Formula: see text] algebra has [Formula: see text] Kač–Moody component, and α = k−/k+. As a pre-requisite to our construction, we check the [Formula: see text] Jacobi identities and construct a classical BRST charge. Then, we analyze the quantum BRST charge nilpotency conditions and find the only solution, k+ = k− = −2. The [Formula: see text] algebra is actually isomorphic to the SO(4)-based Bershadsky–Knizhnik nonlinear quasi-superconformal algebra. We argue about the existence of a new string theory with (i) the nonlinearly realized N = 4 worldsheet supersymmetry, (ii) non-unitary matter in a [Formula: see text] representation of k = −2 and c = −6, and (iii) negative 'critical dimension'.
IS THE STANDARD ELECTROWEAK THEORY HAPPY WITH mt~174 GeV?
Authors: HIOKI ZENRŌ , NAJIMA RYUICHI
Published: November 2004

Stimulated by the recent CDF report on the top quark, we have carried out an analysis on the Higgs mass within the minimal standard electroweak theory using the latest data on the W-mass. Although this theory is in quite a happy situation now, we wish to point out that more precise measurements of MW and mt in the future are crucial and they could come to require some new physics beyond it.
CP VIOLATION IN NEUTRAL B DECAYS ON THE ϒ (4S) WITH SYMMETRIC ENERGIES
Authors: BERKELMAN KARL
Published: November 2004

The favored tests of CP violation in B meson decays give sin 2α and sin 2β, where α and β are angles in the unitarity triangle relating the Kobayashi–Maskawa matrix elements. In the classic B Factory experiment sin 2α or sin 2β is obtained by observing a time dependent CP violating asymmetry in the decay of tagged B0, [Formula: see text] pairs, mediated by [Formula: see text] mixing. The same measurement can be performed at a symmetric energy collider operating at the ϒ (4S) resonance, given sufficient luminosity and vertex resolution. That is, provided the vertical spread of the beam at the interaction point is small, for two-event subclasses the centroid separation in measurements of the observed midpoint between the heights of the two decay vertices is a good statistical estimator for the CP violation parameter sin 2α or sin 2β. With a typical detector the number of events needed is about three times what an asymmetric B Factory would require for the same accuracy.
TACHYON CONDENSATES AND ANISOTROPIC UNIVERSE
Authors: MAHAPATRA SWAPNA , MUKHERJI SUDIPTA
Published: November 2004

We investigate the cosmological solutions in closed bosonic string theory in the presence of nonzero tachyon condensate. We specifically obtain time-dependent solutions which describes an anisotropic universe. We also discuss the nature of such time-dependent solutions when small tachyon fluctuations around the condensate are taken into account.
DYNAMICAL GENERATION OF THE GAUGED SU(2) LINEAR SIGMA MODEL
Authors: DELBOURGO R. , SCADRON M. D.
Published: November 2004

The fermion and meson sectors of the quark-level SU(2) linear sigma model are dynamically generated from a meson–quark Lagrangian, with the quark (q) and meson (σ, π) fields all treated as elementary, having neither bare masses nor expectation values. In the chiral limit, the masses are predicted to be mq = fπg, mπ = 0, mσ = 2mq, and we also find that the quark–meson coupling is [Formula: see text], the three-meson coupling is [Formula: see text] and the four-meson coupling is λ = 2g2 = g′/fπ, where fπ ≃ 90 MeV is the pion decay constant and Nc = 3 is the color number. By gauging this model one can generate the couplings to the vector mesons ρ and A1, including the quark–vector coupling constant gρ = 2π, gρππ, gA1ρπ and the masses mρ ~ 700 MeV, [Formula: see text]; of course the vector and axial currents remain conserved throughout.