bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrating quality management practices with knowledge creation processes
Authors: Linderman Kevin , Schroeder Roger G. , Zaheer Srilata , Liedtke Charles , Choo Adrian S.
Published: September 2004

Several quality thought leaders have considered the role of knowledge in quality management practices. For example, Deming proposed The Deming System of Profound Knowledge™ that dealt explicitly with knowledge. However, various authors in the quality field diverge considerably when contemplating knowledge. We propose an integrated view of quality and knowledge using Nonaka's theory of knowledge creation. This integrated view helps illuminate how quality practices can lead to knowledge creation and retention. The knowledge perspective also provides insight into what it means toeffectivelydeploy quality management practices. Previous empirical research noted the importance of effective deployment, but provided little insight into what effective deployment means. This research argues that quality management practices create knowledge, which leads to organizational performance. Taking a knowledge‐based view (KBV) of the firm provides a deeper understanding of why some organizations are more successful at deploying quality management practices than others.
Recruitment of osteoclast precursors by stromal cell derived factor‐1 (SDF‐1) in giant cell tumor of bone
Authors: Liao Ted S. , Yurgelun Matthew B. , Chang Seong‐Sil , Zhang Hui‐Zhu , Murakami Koko , Blaine Theodore A. , Parisian May V. , Kim William , Winchester Robert J. , Lee Francis Young‐In
Published: September 2004

Giant cell tumor (GCT) of bone is a unique bone lesion that is characterized by an excessive number of multinucleated osteoclasts. GCT consists of neoplastic stromal cells, multinucleated osteoclasts and their precursors, thus serving as a naturally occurring human disease model for the study of osteoclastogenesis. It still remains unclear how stromal cells of GCT recruit osteoclast precursors. In the present study, we characterized the cellular components of GCT and confirmed the presence of CD14+ ‐monocytes/CD68+ ‐macrophages and CD34+ ‐hematopoetic stem cells that express CXCR4, a specific receptor for SDF‐1; SDF‐1 gene expression and presence of SDF‐1 protein were confirmed by real time RT‐PCR, in situ hybridization, and immunohistochemistry in the GCT tissue and cultured cells. SDF‐1 was present at 25–50 ng/ml in the conditioned media from the GCT cultures, which is in the range of physiological chemotactic concentration. Migration of osteoclast precursors was 2.5‐fold higher in response to GCT conditioned media compared to the control media; and migration was inhibited by an average of 36% with anti‐SDF‐1 neutralizing antibody or competing recombinant SDF‐1. These results suggest that SDF‐1 is one of the significant chemoattractant factors involved in the recruitment of hematopoietic osteoclast precursor cells during tumor‐induced osteoclastogenesis. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Mutation hotspots in the human porphobilinogen deaminase gene: Recurrent mutations G111R and R173Q occurring at CpG motifs
Authors: Schneider‐Yin X. , Hergersberg M. , Schuurmans M. M. , Gregor A. , Minder E. I.
Published: September 2004

Summary: Acute intermittent porphyria (AIP) is an inherited disorder in the haem biosynthetic pathway caused by a partial deficiency of porphobilinogen (PBG) deaminase. To date, more than 200 different mutations have been identified in the PBG deaminase gene (PBGD) in AIP patients from various countries and ethnic groups. While the majority of the PBGD gene mutations, including most of the mutations occurring at CpG dinucleotides, are family‐specific, a few CpG mutations have been observed in a number of AIP patients of European origin. To study the origin of these common CpG mutations, eight intragenic single‐nucleotide polymorphisms (SNPs) in the PBGD gene, as well as eight microsatellites flanking the gene in chromosome 11 were used to construct haplotypes in six AIP families of German, Polish and Swiss origins who carried either G111R (4707G>;A) or R173Q (6391G>;A) mutations. Among the three R173Q families, three distinct haplotypes were found to be cosegregated with the mutation. One Swiss and one German G111R family shared partially an intragenic and its extended microsatellite haplotype, whereas the Polish G111R family showed a unique haplotype. These results indicated that the recurrent CpG mutations that exist in the European AIP population can be either of ancestral origins or derived from de novo events.
Correlation between enzyme activity and substrate storage in a cell culture model system for Gaucher disease
Authors: Schueler U. H. , Kolter T. , Kaneski C. R. , Zirzow G. C. , Sandhoff K. , Brady R. O.
Published: September 2004

Summary: Gaucher disease, the most common sphingolipidosis, is caused by a decreased activity of glucosylceramide β‐glucosidase, resulting in the accumulation of glucosylceramide in macrophage‐derived cells known as Gaucher cells. Much of the storage material is thought to originate from the turnover of cell membranes, such as phagocytosed red and white blood cells. In this study, an in vitro model of Gaucher disease was developed by treating the murine macrophage cell line J774 with a specific inhibitor of glucosylceramide β‐glucosidase, conduritol B‐epoxide, and feeding red blood cell ghosts, in order to mimic the disease state. It was found in this model system that glucosylceramide β‐glucosidase activity could be reduced to about 11–15! of the normal control level before increased storage of glucosylceramide occurred. This in vitro system allows insight into the correlation between enzyme activity and lipid storage as predicted by the theory of residual enzyme activity that was proposed by Conzelmann and Sandhoff.
Gaucher disease: Variability in phenotype among siblings
Authors: Amato D. , Stachiw T. , Clarke J. T. R. , Rivard G. E.
Published: September 2004

Summary: Although many mutations of the GBA gene have been described as causing Gaucher disease, there is generally poor correlation between genotype and phenotype, with a few exceptions. However, most previous reports of genotype–phenotype correlation have involved unrelated individuals, who, even if they share the same mutations, are not as genetically close as siblings. We havestudied 24 groups (mostly pairs) of Canadian siblings with type I (non‐neuronopathic) Gaucher disease. Since most Canadian provinces have adopted similar criteria for instituting enzyme replacement therapy (ERT), the age at which ERT is begun can serve as a rough surrogate for disease severity, and concordance (or lack of concordance) can be examined between siblings. In 14 of the 24 sibling families, there was sibling concordance: either both siblings were not on ERT, or both were on ERT and had begun at roughly the same age. In these families, there was also much similarity in the clinical features of the disease between siblings. In the other 10 families there was lack of sibling concordance, with only one sibling receiving ERT (or, in one family with three affected siblings, two of three on ERT). In these families, there was also much discrepancy between siblings in the clinical features (as might be expected in a setting where the guidelines for starting ERT are relatively uniform). Possible reasons for thediscordances between siblings include macro‐environmental and micro‐environmental differences. The latter may include micro‐environments at the level of the cell (e.g. lysosomal pH, alternative substrates) or at the level of the chromosome (contiguous genes, modifier genes, neutral polymorphisms in GBA).
Pregnancy in a patient with mucopolysaccharidosis type IH homozygous for the W402X mutation
Authors: Hendriksz C. J. , Moss G. M. , Wraith J. E.
Published: September 2004

Summary: We present a patient with MPS IH, homozygous for the W402X mutation. The patient was treated by bone marrow transplantation at age 14 months. The patient became pregnant at age 21 years. Because of concerns about her own health, the patient opted for a termination.
Severe lactic acidosis and acute thiamin deficiency: A report of 11 neonates with unsupplemented total parenteral nutrition
Authors: Thauvin‐Robinet C. , Faivre L. , Barbier M. L. , Chevret L. , Bourgeois J. , Netter J. C. , Grimaldi M. , Geneviève D. , Ogier de Baulny H. , Huet F. , Saudubray J. M. , Gouyon J. B.
Published: September 2004

Summary:
Succinyl‐CoA:3‐ketoacid transferase (SCOT) deficiency in a new patient homozygous for an R217X mutation
Authors: Longo N. , Fukao T. , Singh R. , Pasquali M. , Barrios R. G. , Kondo N. , Gibson K. M.
Published: September 2004

Summary: SCOT deficiency presents with persistent excess of ketones leading to ketoacidosis. Here we report patient GS15, homozygous for a novel R217X mutation, who had the first apparent ketoacidotic crisis at 8 months of age. Before confirmation of diagnosis, daily dialysis was the only mechanism by which to normalize her persistent metabolic acidosis of unknown aetiology.
Filter paper cards contaminated with EMLA cream produce artefacts on acylcarnitine analysis
Authors: Kuster T. , Torresani T. , Kleinert P. , Durka S. , Neuheiser F. , Heizmann C. W. , Troxler H.
Published: September 2004

Summary: Electrospray ionization tandem mass spectrometry is a widely applied method for the analysis of acylcarnitines in blood samples spotted on filter paper cards (Guthrie cards). When the filter paper cards are contaminated by EMLA cream, highly intense signals at m/z 221 and 235 are detected under ESI‐MS/MS conditions, monitoring for precursors of m/z 85. These signals correspond to the active ingredients prilocaine and lidocaine in EMLA and overlap with the signals from the isotopically labelled internal standards (2H3)propionyl carnitine and (2H3)butyrylcarnitine. This interference prevents the proper quantification of the two short‐chain acylcarnitines when samples are analysed without derivatization.
The expanding spectrum of disorders with elevated plasma chitotriosidase activity:An update
Authors: Michelakakis H. , Dimitriou E. , Labadaridis I.
Published: September 2004

Summary: A striking elevation of plasma chitotriosidase activity, greater than 150 times the normal median value, was found in two galactosialidosis patients. Furthermore, increased plasma chitotriosidase activity, 10–53 times the normal median value, was also observed in fucosidosis, glycogen storage disease type IV, Alagille syndrome and hydrops fetalis due to congenital herpes virus infection.
Anthropogenic black carbon and fine aerosol distribution over Europe
Authors: Schaap M. , Van Der Gon H. A. C. Denier , Dentener F. J. , Visschedijk A. J. H. , Van Loon M. , ten Brink H. M. , Putaud J.‐P. , Guillaume B. , Liousse C. , Builtjes P. J. H.
Published: September 2004

We present a model simulation for the year 1995 accounting for primary particles, which are an important component of fine aerosols over Europe. A new emission inventory for black carbon (BC) was developed on the basis of the recent European emission inventory of anthropogenic primary particulate matter (Coordinated European Programme on Particulate Matter Emission Inventories, Projections and Guidance (CEPMEIP)). The annual BC emissions of Europe and the former Soviet Union for 1995 are estimated at 0.47 and 0.26 Tg C, respectively, with highest contributions from transport (off‐road and on‐road) and households. Modeled BC concentrations range from ≤0.05 μg/m3 in remote regions to more than 1 μg/m3 over densely populated areas. The modeled BC concentration is about 25% of the total primary aerosol concentration. The primary aerosol fields were combined with previously calculated secondary aerosol concentrations to obtain an estimate of the total anthropogenic fine aerosol distribution. Modeled BC levels contribute only 4–10% to fine aerosol mass, whereas sulphate and nitrate contribute 25–50 and 5–35%, respectively. Comparison with experimental data revealed that the model underestimates PM2.5 levels, mostly caused by the underprediction of total carbonaceous material (BC and OC) by a factor of ∼2. The underestimation can partly be explained by the influence of local emissions, measurement uncertainties, natural sources, and representation of wet deposition. However, the uncertainties associated with the emission inventory for BC (and total PM) may be the most important cause for the discrepancy. In comparison with previous studies, our BC emission estimate is a factor of 2 lower, caused by the choice of more recent emission factors. Therefore a better knowledge of emission factors is urgently needed to estimate the BC (and PM) emissions reliably.
Measurements of the hemispherical‐directional reflectance of snow at fine spectral and angular resolution
Authors: Painter Thomas H. , Dozier Jeff
Published: September 2004

We present 2 days' measurements of the hemispherical‐directional reflectance factor (HDRF) of snow made at fine spectral and angular resolution with the Automated Spectro‐Goniometer (ASG) for the range of solar zenith angles (θ0 = 40°–50°) and snow textures (surface grain size = 80–280 μm). Measurements of the stratigraphy of snow texture and density accompanied each day's suite of measurements. These measurements represent the most detailed available in terms of angular and spectral resolution. The HDRF for fine grain, faceted snow exhibited a local backscattering peak at the view zenith near the solar zenith angle, whereas those for medium grain, clustered snow did not have a local backscattering peak. The HDRF decreased at all wavelengths for an increase in grain radius from 80 μm to 280 μm. However, the decrease in HDRF in the visible wavelengths was largest at θr = 80° in the forward direction and largest for λ > 1.8 μm near θr = 30° in the backward direction. As solar zenith angle decreased from 47° to 41°, the HDRF increased near nadir for λ ≤ 1.03 μm but decreased with coherent angular structure for λ > 1.03 μm. We compared forward radiative transfer modeling results with the HDRF measurements. The forward model used single‐scattering parameters for ice spheres with radii that matched the surface‐area‐to‐volume ratio derived from stereological analysis of snow samples and a stratigraphic distribution of optical depths from measured density and modeled extinction efficiency. All HDRF models underestimated reflectance for λ > 1.30 μm and had large absolute errors in the perpendicular plane. Mean absolute RMS errors in reflectance for the fine grain, faceted snow case were 0.09 at λ = 1.3 μm and 0.14 at λ = 1.85 μm. Mean absolute RMS errors for the medium grain, clustered snow were 0.04–0.06 at λ = 1.3 μm and 0.04–0.06 at λ = 1.85 μm. The models for the more spherical medium grain snow had better overall spectral and angular fits than those for the nonspherical fine grain snow. The spherical radii inferred from the surface‐area‐to‐volume ratio from stereological analysis of snow with nonspherical particles have a greater effective path length than the actual snow particles, resulting in underestimates of hemispherical‐directional reflectance.
Recharge mechanism of near‐equatorial hydrogen on Mars: Atmospheric redistribution or sub‐surface aquifer
Authors: Feldman W. C. , Head J. W. , Maurice S. , Prettyman T. H. , Elphic R. C. , Funsten H. O. , Lawrence D. J. , Tokar R. L. , Vaniman D. T.
Published: September 2004

The geographical distribution of water‐equivalent‐hydrogen (WEH) near the equator of Mars was compared with the topography and distribution of atmospheric water vapor to constrain possible recharge mechanisms of near‐surface water (<1 m of the surface). Recharge through a subsurface conduit provided by an aquifer, although possible, seems less likely than recharge through the atmosphere. Although the spatial distribution of WEH does not correspond to the current distribution of water vapor in the atmosphere, several terrestrial analogs indicate that dynamics of atmospheric circulation during periods of higher obliquity prior to the present epoch can qualitatively account for the observed WEH distribution.
Detecting the effect of climate change on Canadian forest fires
Authors: Gillett N. P. , Weaver A. J. , Zwiers F. W. , Flannigan M. D.
Published: September 2004

The area burned by forest fires in Canada has increased over the past four decades, at the same time as summer season temperatures have warmed. Here we use output from a coupled climate model to demonstrate that human emissions of greenhouse gases and sulfate aerosol have made a detectable contribution to this warming. We further show that human‐induced climate change has had a detectable influence on the area burned by forest fire in Canada over recent decades. This increase in area burned is likely to have important implications for terrestrial emissions of carbon dioxide and for forest ecosystems.
Global CO2 transport simulations using meteorological data from the NASA data assimilation system
Authors: Kawa S. R. , Erickson D. J. , Pawson S. , Zhu Z.
Published: September 2004

We present a first analysis of atmospheric CO2 transport using meteorological data from the NASA finite volume data assimilation system (FVDAS). The analyzed meteorological fields are used along with climatological surface sources and sinks in an off‐line, forward transport simulation for 1998–2000. Analysis of model diagnostics and comparisons to previous results indicates that the model performance is consistent with that of most previous global transport models. The model interhemispheric gradients along with the timing and magnitude of the CO2 seasonal cycle are discussed, providing inferences regarding the northern biosphere, tropical land, and southern ocean fluxes. Global distributions of column‐integrated CO2 are presented to provide a basis for measurement requirements for the design of satellite‐based instruments for atmospheric CO2 column. On the synoptic scale we find a significant benefit in using the FVDAS analyzed winds for comparisons to data. At near‐equatorial observation sites, the model correctly simulates the observed atmospheric composition transition associated with the latitudinal movement of the ITCZ. Comparison to daily data from continuous analyzer sites shows the model captures a substantial amount of the observed synoptic variability due to transport changes. These results show the potential to use high temporal and spatial resolution remote sensing data to constrain CO2 surface fluxes, and they form the starting point for developing an operational CO2 assimilation system to produce high‐resolution distributions of atmospheric CO2 and quantitative estimates of the global carbon budget.
Direct measurement of the hydration state of ambient aerosol populations
Authors: Santarpia Joshua L. , Li Runjun , Collins Don R.
Published: September 2004

During the summer of 2002 a modified tandem differential mobility analyzer (TDMA) was used to examine the size‐resolved hydration state of the ambient aerosol in southeast Texas. Throughout the study period the sampled aerosol had been exposed to a relative humidity (RH) greater than 80% before or soon after sunrise, while the ambient RH during sampling ranged from about 50 to 70%. To examine any possible size dependence, while also maximizing time resolution, 160 and 320 nm particles were analyzed. To assist in the interpretation of these data, a second, RH‐scanning, TDMA was concurrently operated to directly characterize the deliquescence and crystallization properties of the aerosol. The hygroscopic growth of the more hygroscopic population of 160 and 320 nm particles was below that predicted for pure inorganics such as ammonium sulfate, suggesting the sampled particles were composed of mixtures of soluble and insoluble compounds. Although there were slight variations in the measured properties over the course of the study, those particles that were observed to exhibit hygroscopic growth hysteresis were almost always present as metastable aqueous solutions.
Numerical simulation of snow saltation and suspension in a turbulent boundary layer
Authors: Nemoto M. , Nishimura K.
Published: September 2004

A new numerical model was developed to describe the development of drifting snow on a flat surface. The model uses Lagrangian stochastic theory to account for turbulence effects on the suspension of snow grains, and also includes aerodynamic entrainment, the grain‐bed collision process, wind modification by the grains, and a distribution of grain sizes. The calculated wind profile, shear stress, and mass flux near the surface agreed quantitatively with previous wind tunnel experiments. Because of turbulence, snow grains can reach 10 m high, a results that agrees with recent measurements but had not previously been simulated using saltation models. We also found that the steady state fluid shear stress exceeded the threshold stress, meaning that the grains were continually entrained by the fluid. A distinct change in the mass flux profile occurred at 0.1 m high for the following reason. Below 0.1 m, the particle inertia dominated the grain motion and turbulence had only a small effect on the motion; in contrast, above 0.1 m, most particles were less than 100 μm in diameter and their motion was mainly affected by the turbulence and not inertia. That is, the particles above 0.1 m were in suspension mode.
Comparison of Stratospheric Aerosol and Gas Experiment (SAGE) II version 6.2 water vapor with balloon‐borne and space‐based instruments
Authors: Taha Ghassan , Thomason Larry W. , Burton Sharon P.
Published: September 2004

A new version of the SAGE II data products was released in October 2003. The primary change to the algorithm dealt with improvements in the water vapor product such as eliminating the dry bias in the lower stratosphere and reducing the sensitivity to aerosol contamination. Results of an extensive comparison of SAGE II version 6.2 water vapor and various correlative measurement from balloon‐borne and space‐based instruments illustrate significant improvement over the previous version (version 6.1). In general, the agreement was within 10% or less over an altitude range of 15–40 km when compared with frost point hygrometer, HALOE, POAM III, and ILAS and 15–20% when compared to MkIV. Above 40 km, SAGE II water vapor profiles are often noisy and show an increasingly positive bias. On the basis of comparison with HALOE a basic screening criteria would consist of electing measurements where the aerosol extinction coefficient at 1020 nm exceeds 2 × 10−4 km−1 and water vapor uncertainty exceeds 50%.
Antiviral and Antiproliferative Activity in vitro of some New Benzimidazole Derivatives
Authors: Castelli Mario , Malagoli Monica , Lupo Lucia , Riccomi Tiziana Rossi , Casolari Chiara , Cermelli Claudio , Zanca Andrea , Baggio Giosuè
Published: September 2004

Abstract: The antiviral and antiproliferative activity of new compounds having n‐benzenesulphony 1–2 (2 or 3‐pyridylethyl) benzimidazole as a base structure were studied in vitro. Their antitumour activity against human chronic myeloid leukaemia cells was evaluated and compared with that of equimolar doses of daunorubicin. Only compound 7a, with the presence of both the pyridyl moiety bound at the ethylenic bridge in C‐2 of benzimidazole and the nitro‐group in the benzene ring, displays a selective antiproliferative effect against certain leukaemia cells and a good antiviral activity especially towards the Coxsackie B5 virus. However, it should be noted that, in the case of hydroxybenzyl‐benzimidazole, resistance also builds up to compound 7a, the Coxsackie B5 virus developing resistance to it after about ten runs. Cytotoxicity tests show that many of these substances are well tolerated by the VERO cells. The mechanism of action is still unclear.
Differentiation of Disulfiram Effects on Central Catecholamines and Hepatic Ethanol Metabolism
Authors: Karamanakos Petros N. , Pappas Periklis , Stephanou Panayiotis , Marselos Marios
Published: September 2004

Abstract: Disulfiram is used in the treatment of chronic alcoholism, because of the unpleasant symptoms it provokes after ethanol intake. The underlying mechanism is believed to be the accumulation of acetaldehyde in the blood, due to inhibition of the liver aldehyde dehydrogenases. In addition, it is known that disulfiram also has some neurotoxic properties. The aim of our study was to investigate the relationship between the pharmacological and neurotoxicological properties of disulfiram with respect to the doses applied. Increasing doses of disulfiram (25, 50, 75, 100 and 150 mg/kg) were administered intraperitoneally to Wistar rats and the hepatic enzyme activities of alcohol and aldehyde dehydrogenases were measured. Also, in two brain subregions (midbrain and hypothalamus) the levels of noradrenaline, dopamine, 3,4‐dihydroxyphenylacetic acid and homovanillic acid were determined. The higher dose of disulfiram (150 mg/kg) produced lethal effects in all treated animals. Aldehyde dehydrogenase activities were inhibited by disulfiram in a dose‐dependent way, while alcohol dehydrogenase was not affected at all. Concerning the levels of brain biogenic amines, disulfiram produced a significant reduction in noradrenaline and an increase in dopamine levels in both structures of the brain, in a dose‐dependent way. However, the lowest dose applied (25 mg/kg) had no effects on brain catecholamines. It is known that high doses of disulfiram may cause severe encephalopathy and peripheral neuropathy in humans, which could be attributed to the impairment of the metabolism of brain biogenic amines, due to inhibition of dopamine‐β‐hydroxylase. Our experimental data show that disulfiram affects the level of brain biogenic amines at dose levels higher than those inhibiting the activity of aldehyde dehydrogenase. Therefore, in clinical practice ‘disulfiram reaction’ could still be achieved with a low dosage regimen not producing neurotoxicity.
Enhancement of local electric field in an electrorheological system
Authors: Jie H. , Shen M. , Xu J. , Chen W. X. , Jin Y. , Peng W. N. , Fu X. B. , Zhou L. W.
Published: September 2004

A local electric field distribution in the midplane between two spherical metal particles under an applied electric field is measured for comparison with the real electrorheological system. It was found that the ratio of the maximum value of local electric field to applied electric field is not a constant as most theoretical models predicted.
Surface relief gratings on polymer dispersed liquid crystalsby polarization holography
Authors: Mazzulla A. , Pagliusi P. , Provenzano C. , Russo G. , Carbone G. , Cipparrone G.
Published: September 2004

We report the observation of surface relief gratings (SRGs) on polymer dispersed liquid crystal films after polarization holographic recording, demonstrating the formation of SRGs in systems without azo compounds, where photoisomerization and chromophore reorientation processes do not occur. Permanent SRGs, several hundred nanometers deep, are recorded on the surface of a polymeric material containing oriented liquid crystal droplets. The results suggest that SRG growth under uniform intensity irradiation is not exclusively related to the photoisomerization, but is a more general phenomenon which can involve different photoinduced chemical and physical mechanisms sensitive to the light polarization state. These effects contribute to the formation of anisotropic structures during the recording process.
Fabrication of high-quality strain-relaxed thin SiGe layers on ion-implanted Si substrates
Authors: Sawano K. , Koh S. , Shiraki Y. , Ozawa Y. , Hattori T. , Yamanaka J. , Suzuki K. , Arimoto K. , Nakagawa K. , Usami N.
Published: September 2004

We fabricated high-quality strain-relaxed thin SiGe layers by Ar ion implantation into Si substrates before epitaxial growth. The surface of 100-nm-thick Si0.8Ge0.2 layers, the relaxation ratio of which was more than 80%, was found to be very smooth, with a rms roughness of 0.34 nm. Cross-sectional transmission electron microscopy analysis confirmed that strain-relieving dislocations were effectively generated due to the ion-implantation-induced defects and confined in the vicinity of the heterointerface, resulting in a dislocation-free SiGe surface. Moreover, in-plane strain-field fluctuation was found to be largely reduced by this ion implantation method.
Carrier removal in lattice-mismatched InGaP solar cells under 1-MeV-electron irradiation
Authors: Ekins-Daukes N. J. , Lee H. S. , Sasaki T. , Yamaguchi M. , Khan A. , Takamoto T. , Agui T. , Kamimura K. , Kaneiwa M. , Imaizumi M. , Ohshima T. , Kamiya T.
Published: September 2004

Radiation-induced majority carrier removal is investigated from n+∕p− lattice-mismatched In0.56Ga0.44P solar cells under 1-MeV-electron irradiation. The change in carrier concentration in the 1×1017cm−3p− base layer is determined using standard capacitance–voltage techniques and found to proceed at a rate Rc=1.3cm−1, in agreement with that observed in lattice-matched InGaP. However, the observation of an increased short-circuit current and short-wavelength quantum efficiency over the unirradiated values at electron fluence levels in excess of 3×1015cm−2, allows the carrier concentration from the n+ emitter layer to be measured. By modeling the quantum efficiency of these solar cells, it is shown that the main photoresponse from these lattice-mismatched solar cells is due to drift transport, making the spectral response highly sensitive to changes in the width of the depletion region. Using this technique, the carrier concentration in the 2×1018cm−3 n+ emitter layer is found to be reduced to 1×1018cm−3 after exposure to an electron fluence of 3×1015cm−2.
Scanning laser imaging of dissipation in YBa2Cu3O7−δ-coated conductors
Authors: Abraimov D. , Feldmann D. M. , Polyanskii A. A. , Gurevich A. , Daniels G. , Larbalestier D. C. , Zhuravel A. P. , Ustinov A. V.
Published: September 2004

We investigate dc-current flow in high-jc YBa2Cu3O7−δ-coated conductors by low-temperature laser scanning microscopy (LTLSM) and correlate the LTLSM response to magneto-optical imaging (MOI) and grain boundary (GB) misorientation. Because the voltage response measured by LTLSM is associated with the local electric field, while MOI shows the local magnetic field, the combination of these two techniques unambiguously shows that the dominant sources of dissipation and easy flux flow occur at and near GBs. By correlating LTLSM images to grain misorientation maps determined by electron backscatter diffraction (EBSD), we can directly observe the overloading of current paths through low-angle GBs neighboring higher-angle GBs.
Attenuation contrast between biomolecular and inorganic materials at terahertz frequencies
Authors: Chan T. L. J. , Bjarnason J. E. , Lee A. W. M. , Celis M. A. , Brown E. R.
Published: September 2004

Wideband photomixing spectroscopy is used in the present work to contrast the transmission spectra of macromolecules commonly found in biomaterials such as potato starch, wheat flour and cornstarch, and proteins (Cytoplex™), and micromolecules such as sucrose, and inorganic materials such as sodium bicarbonate, and calcium sulfate. Powdered samples were measured at 0.1–0.5THz frequencies. A significant difference in attenuation is found between these samples. At 300GHz starch shows an absorption coefficient of ∼6cm−1 whereas Cytoplex shows 1–3cm−1, while inorganic micromolecules have ∼1cm−1. The absorption in starch increases rapidly with frequency tending to follow a power law α=fn with n typically between 1.5 and 2.0. In contrast, protein materials display a slower dependence on frequency with n between 1.0 and 1.5, and simple molecules show the least n among all three categories. The difference between these ubiquitous macromolecular and micromolecular materials is explained in terms of water content and molecular structure.
Enhanced back reflectance and quantum efficiency in Cu(In,Ga)Se2 thin film solar cells with a ZrN back reflector
Authors: Malmström Jonas , Schleussner Sebastian , Stolt Lars
Published: September 2004

A reactively sputtered ZrN reflector layer on top of the conventional Mo back contact yields enhanced absorber/back contact reflectance in Cu(In,Ga)Se2 thin film solar cells. Improved long wavelength quantum efficiency is demonstrated with a ZrN reflector at a Cu(In,Ga)Se2 thickness of 0.5 μm. The optical gain with respect to a standard Mo back contact is initially offset by increased back contact recombination and contact resistance, but these electronic losses can be suppressed by Ga grading of the absorber or by inclusion of a contact layer of MoSe2. This allows for a significantly improved power conversion efficiency of devices with sub-micron Cu(In,Ga)Se2 thickness.
Solventless ordering of colloidal particles through application of patterned elastomeric stamps under pressure
Authors: Suh Kahp Y. , Yoon Hyunsik , Lee Hong H. , Khademhosseini Ali , Langer Robert
Published: September 2004

We report on an ordering phenomenon of polystyrene beads that occurs when pressure is applied to the colloidal particles between a solid substrate and a patterned elastomeric stamp while maintaining the temperature above the particle’s glass transition temperature. The filling time is calculated using a simple two-dimensional squeeze flow theory, which successfully explains the effects of pressure, temperature, size of beads, and stamp geometries on the ordering time.
Silicon optical nanocrystal memory
Authors: Walters R. J. , Kik P. G. , Casperson J. D. , Atwater H. A. , Lindstedt R. , Giorgi M. , Bourianoff G.
Published: September 2004

We describe the operation of a silicon optical nanocrystal memory device. The programmed logic state of the device is read optically by the detection of high or low photoluminescence intensity. The suppression of excitonic photoluminescence is attributed to the onset of fast nonradiative Auger recombination in the presence of an excess charge carrier. The device can be programmed and erased electrically via charge injection and optically via internal photoemission. Photoluminescence suppression of up to 80% is demonstrated with data retention times of up to several minutes at room temperature.
Hydrogen-induced defects and degradation in oxide ferroelectrics
Authors: Xiong K. , Robertson J.
Published: September 2004

We investigate hydrogen-induced defects in BaTiO3, PbTiO3, PbZrO3, and strontium bismuth tantalate (SBT). We find that interstitial hydrogen produces a shallow level and OH− ions leading to loss of switchable polarization if the oxide’s band gap is under about 4.2eV, but hydrogen is deep in wide gap compounds like BaZrO3. In SBT, hydrogen is more stable in the Bi–O layer.
Single-electron tunneling to insulator surfaces measured by frequency detection electrostatic force microscopy
Authors: Bussmann E. , Kim Dong Jun , Williams C. C.
Published: September 2004

Single-electron tunneling events between a metal probe and an insulator surface are measured by frequency detection electrostatic force microscopy. Single-electron tunneling events typically cause 1–10Hz shifts in the 300kHz resonance frequency of the oscillating force probe. The frequency shifts appear only within a sub-2nm tip–sample gap and their magnitude is roughly uniform under fixed experimental conditions. An electrostatic model of the probe–sample system yields results consistent with the measurements.
High-resolution Raman microscopy of curled carbon nanotubes
Authors: Ko Hyunhyub , Pikus Yuri , Jiang Chaoyang , Jauss Andrea , Hollricher Olaf , Tsukruk Vladimir V.
Published: September 2004

Patterned carbon nanotube assemblies with bent nanotube bundles were investigated with combined atomic force microscopy and confocal Raman imaging spectroscopy to identify conditions of carbon nanotubes in the bent state. We showed that the tangential G mode on Raman spectra systematically shifts downward upon nanotube bending as was predicted earlier. This lower frequency shift is attributed to the tensile stress, which results in the loosening of C–C bonds in the outer nanotube walls.
Properties of photoluminescence in type-II ZnMnSe∕ZnSeTe multiple quantum wells
Authors: Lin C. M. , Chen Y. F.
Published: September 2004

The optical properties of type-II ZnMnSe∕ZnSeTe multiple quantum wells were investigated by photoluminescence (PL) measurement. It was found that the peak position of PL spectra shows a giant blueshift under a moderate optical excitation level. The giant blueshift can be interpreted in terms of the band-bending effect due to the spatially photoexcited carriers in a type-II alignment. We also found that the PL spectra exhibit a large in-plane polarization with respect to ⟨110⟩ axis with the polarization degree up to 12.4%. We showed that the polarization does not depend on the excitation intensity as well as temperature, which excludes the possibility of extrinsic mechanisms related to the in-plane anisotropy. The observed anisotropic effects of ZnMnSe∕ZnSeTe multiple quantum wells were attributed to the intrinsic property of the orientation of chemical bonds at the heterointerface of the type-II band alignment.
Gas phase chlorination of hydrogen-passivated silicon surfaces
Authors: Rivillon Sandrine , Amy Fabrice , Chabal Yves J. , Frank Martin M.
Published: September 2004

A simple method is described to functionalize hydrogen-passivated Si(111) and Si(100) surfaces with chlorine (Cl2) gas. Infrared-absorption spectroscopy provides a positive identification of chlorination and mechanistic information on the chlorination of H-terminated Si surfaces, and on the structure and stability of chlorine-terminated Si surfaces (Cl∕Si). We find that the chlorination process does not change the surface morphology: H∕Si(111)-(1×1) surfaces and HF-etched Si(100) surfaces remain atomically flat and atomically rough, respectively, upon chlorination. Chlorinated S: surfaces are stable in a nitrogen atmosphere for over 12 hours.
On the potential distribution in Hall thrusters
Authors: Keidar Michael , Gallimore Alec D. , Raitses Yevgeny , Boyd Iain D.
Published: September 2004

A model of the plasma flow in a Hall thruster channel is developed that takes into account the two-dimensional current conservation effect and relies on some experimental input parameters, such as magnetic field and electron temperature distribution. The model is an attempt to explain the experimentally found nonuniform potential distribution across the thruster channel. This effect is explained by the change of the electron mobility across a magnetic field due to the magnetic field gradient and due to the electron current along the magnetic field driven by the electron temperature gradient.
Postprocessing annealing effects on direct current and microwave performance of AlGaN∕GaN high electron mobility transistors
Authors: Lee Jaesun , Liu Dongmin , Kim Hyeongnam , Lu Wu
Published: September 2004

The effects of postprocessing annealing on direct current, radio frequency small signal, and power performances of AlGaN∕GaN high electron mobility transistors with a gate-length of 0.2μm were investigated. The postannealing technique can improve the device performance, especially, after 10min postannealing at 400°C, the gate-to-drain breakdown voltage of devices exhibits remarkable improvement from 25 to 187V. The maximum extrinsic transconductance increases from 223 to 233mS∕mm at a drain bias of 10V after 10min annealing at 400°C. The maximum drain current at a gate bias of 1V increases from 823 to 956mA∕mm. After annealing, the values of the unity current gain cut-off frequency and the maximum oscillation frequency increases from 24 and 80GHz to 55 and 150GHz, respectively. The output power and gain at 10GHz were improved from 16.4dBm and 11.4dB to 25.9dBm and 19dB, respectively.
Receiving and transmitting light-like radio waves: Antenna effect in arrays of aligned carbon nanotubes
Authors: Wang Y. , Kempa K. , Kimball B. , Carlson J. B. , Benham G. , Li W. Z. , Kempa T. , Rybczynski J. , Herczynski A. , Ren Z. F.
Published: September 2004

We present optical measurements of random arrays of aligned carbon nanotubes, and show that the response is consistent with conventional radio antenna theory. We first demonstrate the polarization effect, the suppression of the reflected signal when the electric field of the incoming radiation is polarized perpendicular to the nanotube axis. Next, we observe the interference colors of the reflected light from an array, and show that they result from the length matching antenna effect. This antenna effect could be used in a variety of optoelectronic devices, including THz and IR detectors.
Energy-angle correlation of electrons accelerated by laser beam in vacuum
Authors: Chen Z. , Ho Y. K. , Xie Y. J. , Zhang S. Y. , Yan Z. , Xu J. J. , Lin Y. Z. , Hua J. F.
Published: September 2004

The correlation between the outgoing energy and the scattering angle of electrons accelerated by a laser beam in vacuum has been investigated. Essentially, the single-valued function of the correlation, derived from classical electrodynamics Compton scattering for a plane wave, is broadened to a band. It means electrons with the same outgoing energy will have an angular spread. An equation to describe this correlation has been derived. Dependence of the spread width of scattering angle on laser beam parameters is examined, and physical explanations of these features are given. The results are found to be consistent with the simulation results for a proposed vacuum laser acceleration scheme: the capture and acceleration scenario.
Morphological variation of multiwall carbon nanotubesin supercritical water oxidation
Authors: Chang Jia-Yaw , Lo Bertrand , Jeng Meili , Tzing Shin-Hwa , Ling Yong-Chien
Published: September 2004

Multiwall carbon nanotubes (MWNTs) with different morphology were prepared using supercritical water (SCW) oxidation and investigated by transmission electron microscope (TEM) and electron energy-loss spectroscopy (EELS). TEM results indicate that the peeling and sharpening of MWNTs are influenced by the etching process in SCW oxidation, of which oxidation time and amount of oxygen used is crucial. A simplified etching model is proposed, which indicates that the difference of mean etching rate between two adjoining blocks causes the morphological variation of MWNTs. The EELS results show change in characteristic energy-loss peaks as a function of total shell numbers along longitudinal axis of individual peeled tube.
Correlation between tumor regression and T cell responses in melanoma patients vaccinated with a MAGE antigen
Authors: Lonchay Christophe , van der Bruggen Pierre , Connerotte Thierry , Hanagiri Takeshi , Coulie Pierre , Colau Didier , Lucas Sophie , Van Pel Aline , Thielemans Kris , van Baren Nicolas , Boon Thierry
Published: September 2004

The cancer-germline gene
MAGE-3
codes for tumor-specific antigens recognized on many tumors by T lymphocytes. A MAGE-3 antigen presented by HLA-A1 has been used in several vaccination trials on metastatic melanoma patients. Only a small minority of patients have shown evidence of tumor regression. Attempts to correlate the tumor rejections with the cytotoxic T lymphocyte (CTL) response against the vaccine have been hampered by the low level of these responses. In noncancerous individuals, the frequency of the T cell precursors against antigen MAGE-3.A1 is ≈4 × 10
-7
CD8 T cells. The diversity of the T cell receptor repertoire of these anti-MAGE-3.A1 precursors was analyzed in one individual. The results indicate that it is very likely that the repertoire comprises >100 clonotypes. On this basis, it is possible to use not only the frequency of CTL precursors in the blood but also the presence of dominant clonotypes to ascertain in patients the existence of anti-MAGE-3.A1 responses as low as 10
-6
of CD8. With this approach, we observed a correlation between tumor regression and anti-MAGE-3.A1 CTL responses in patients vaccinated with a recombinant virus encoding the antigen and also in patients vaccinated with peptide-pulsed dendritic cells. In contrast, for patients showing tumor regression after vaccination with peptide alone, CTL responses were almost never observed. It is possible that even those CTL responses that are below our present detection level can trigger a sequence of events that leads to tumor regression.
A nuclear receptor corepressor transcriptional checkpoint controlling activator protein 1-dependent gene networks required for macrophage activation
Authors: Ogawa Sumito , Lozach Jean , Jepsen Kristen , Sawka-Verhelle Dominique , Perissi Valentina , Sasik Roman , Rose David W. , Johnson Randall S. , Rosenfeld Michael G. , Glass Christopher K.
Published: September 2004

The nuclear receptor corepressor (NCoR) and the related factor known as silencing mediator of retinoic acid and thyroid hormone receptor (SMRT) are essential components of multiprotein complexes that mediate active repression by unliganded nuclear receptors. Recent studies suggest that NCoR and SMRT can interact with and exert repressive effects on several other classes of DNA-binding transcription factors, but the physiological importance of these interactions has not been established. Here, investigation of endogenous transcriptional programs regulated by NCoR in macrophages reveals that NCoR acts as a transcriptional checkpoint for activator protein (AP)-1-dependent gene networks that regulate diverse biological processes including inflammation, cell migration, and collagen catabolism, with loss of NCoR, resulting in derepression of AP-1 target genes. The NCoR corepressor complex imposes an active block of exchange of c-Jun for c-Jun/c-Fos heterodimers, with targeted deletion of the
c-Jun
locus, resulting in loss of NCoR complexes from AP-1 target genes under basal conditions. The checkpoint function of NCoR is relieved by signal-dependent phosphorylation of c-Jun, which directs removal of NCoR/HDAC3/TBL1/TBLR1 complexes through recruitment of a specific ubiquitylation complex, as a prerequisite to the default binding of c-Jun/c-Fos heterodimers and transcriptional activation. The requirement for a checkpoint function to achieve the appropriate dynamic range of transcriptional responses to inflammatory signals is likely to be used by other signal-dependent transcription factors that regulate diverse homeostatic and developmental processes.
Possible Noncausal Bases for Correlations between Low Concentrations of Ambient Particulate Matter and Daily Mortality
Authors: Valberg Peter A.
Published: September 2004

Numerous studies of populations living in areas with good air quality have reported correlations between daily average levels of ambient particulate matter (PM) and daily mortality rates. These associations persist at PM levels below current air quality standards and are difficult to reconcile with the toxicology of PM chemical constituents. The unusual level of lethality per unit PM mass predicted by these associations may result from confounding by unmeasured societal, behavioral, or stress factors. Daily average ambient PM levels may be expected to correlate with societal activity level, because a working population increases PM emissions through increased manufacture, power utilization, construction, demolition, farming, and travel. Also, people's perceived and actual health depend on societal and psychological factors. A stress such as anger strongly increases the risk of death due to heart attack. Societal factors modify mortality as shown by calendar-related changes in mortality that are unrelated to air quality. Cardiovascular and respiratory mortality are correlated to day of the week, end of the month, and to the first week of the year. There is likely a role of such nontoxicologic variables in the PM associations, and without vigorously testing if other variables correlate as well as PM, we may erroneously conclude that reducing already low levels of PM will yield real public health benefits.