bluuebunny/crossref_metadata_2025 huggingface dataset:
A method to assess the variation of urban canyon geometry from sky view factor transects
Authors: Bradley A. V. , Thornes J. E. , Chapman L.
Published: October 2002

It is now possible to generate large quantities of sky view factor (SVF) values due to advances in digital techniques for calculating SVF from hemispherical images. Coupling image acquisition with Global Positioning System (GPS) data now enables transects to be accurately placed, enabling site‐specific SVF analysis in relation to street geometry. This paper examines SVF transects through four land cover classes. The findings indicate that although SVF averages are distinctly different in each of the land cover types, an average SVF value for a particular land use type is not a sufficient estimate at street resolution. Copyright © 2003 Royal Meteorological Society.
Accelerator-Mass-Spectrometer Ages for the Younger Dryas Event in Atlantic Canada
Authors: Mayle Francis E. , Levesque André J. , Cwynar Les C.
Published: October 2002

In Atlantic Canada, bulk-sediment dates for the onset of a late-glacial cooling, widely regarded as the Younger Dryas event, are highly variable, ranging from 14,300 ± 270 to 10,800 ± 100 yr B.P. We present the first accelerator-mass-spectrometer (AMS) 14C dates from Atlantic Canada, at or close to the boundaries of this event, from six sites in New Brunswick and Nova Scotia. The mean of five dates places the onset of this cooling at ca. 10,770 yr B.P.; the inclusion of a sixth, perhaps anomalously old date, changes the mean to 10,880 yr B.P. The termination averages (three dates) ca. 10,000 yr B.P. These dates place the timing of the Younger Dryas event in Atlantic Canada closer in line with the traditional chronozone boundaries of 11,000 and 10,000 yr B.P. in Northwest Europe.
Late Holocene Environmental Changes in Arid Southwestern Madagascar
Authors: Burney David A.
Published: October 2002

A 5000-yr stratigraphic record containing fossil pollen, charcoal, and bones of the extinct Quaternary megafauna from Andolonomby, a hypersaline pond in arid southwestern Madagascar, shows evidence for climatic desiccation beginning about 3000 yr B.P. Pollen spectra shift at this time from primarily arboreal taxa characteristic of forests and woodlands of more mesic western Madagascar, to wooded savanna typical of somewhat drier localities. Between 3000 and 2000 yr B.P., the site became increasingly arid. Charcoal and pollen evidence indicates that increased fire and disturbance occurred at the site beginning ca. 1900 yr B.P., probably signaling the beginning of human settlement in the area. The fossil record suggests that various human and natural factors on the island may have interacted in the subsequent millennium to culminate in the extinction of the entire endemic megafauna.
Soils of an Eolian Analog of the Leasburg Surface, Southern New Mexico
Authors: Gile Leland H.
Published: October 2002

In a dissected, mostly sandy terrain along the Rio Grande valley border of southern New Mexico, a reddish-brown coarse-loamy Haplargid in an eolian deposit has a stage II carbonate horizon that is typical of soils of the Leasburg surface (8000-15,000 yr B.P.). The eolian deposit buries sediments and soils of late Pleistocene age or older. Thus, it does not fit in the chronological framework of the stepped sequence of geomorphic surfaces along the valley border, in which age of the surfaces and their soils increases with increasing elevation of the steps. Because the eolian deposit occurs in isolated areas where its age relative to the stepped sequence cannot be demonstrated geomorphically, soil characteristics are major tools for placing the deposit and its soil in the chronological scheme for the area. On the basis of the stage II carbonate horizon, the eolian deposit is considered to be an eolian analog of Leasburg alluvium. One of the Leasburg Haplargids in eolian sediments on a ridge crest has a total of 23 kg/m2of pedogenic carbonate. Downslope in an area that receives runoff from higher areas, a fine-loamy Haplargid in Leasburg alluvium has 186 kg/m2of carbonate; a nearby coarse-loamy Haplargid that does not receive runoff has only 46 kg/m2of carbonate. Thus, landscape position and texture have a major influence on the total amount of pedogenic carbonate, which can range to more than eightfold in soils of Leasburg age.
A High-Resolution 11,400-Yr Diatom Record from Lake Victoria, East Africa
Authors: Stager J.Curt , Cumming Brian , Meeker Loren
Published: October 2002

Fine-interval (∼30–45 yr) sampling of a core from Lake Victoria's Damba Channel shows that numerous abrupt changes in the lake's diatom assemblages have occurred in response to climatic fluctuations over the past 11,40014C yr. Four distinct climatic phases bounded by sudden transitions are inferred: (1) variably dry ∼11,400–10,000 yr B.P., (2) humid ∼10,000–7200 yr B.P., (3) more seasonal ∼7200–2200 yr B.P., and (4) more arid ∼2200–0 yr B.P., with a dry “Little Ice Age” event ∼600–200 yr B.P. The diatom-inferred paleoclimatic history for northern Lake Victoria closely resembles that inferred from a well-dated pollen record from Pilkington Bay. Spectral analysis of the diatom record reveals strong periodicities including globally distributed ∼2360–2550, ∼1400, ∼1030–1130, and ∼500 cal-yr cycles. Repeated, rapid shifts betweenAulacoseira- andNitzschia-dominated diatom assemblages suggest that post-1960 changes in the lake's phytoplankton communities have had earlier, climate-driven analogs.
The impact of equity option expirations on the prices of non‐expiring options
Authors: Broughton John B. , Chance Don M. , Smith David M.
Published: October 2002

We present evidence that for non‐expiring options in the current expiration cycle, observed prices conform to the prices predicted by the dividend‐corrected Black‐Scholes model in the period prior to, and including, the expiration date. This is generally not true for options that are not in the current expiration cycle or for options during non‐expiration time periods. This evidence is interesting in that it suggests that the dividend‐corrected Black‐Scholes model is more useful as a pricing tool when there is a nearby expiration event affecting options on the same underlying stock. We also find that, during the expiration period, mean absolute pricing errors, a measure of pricing efficiency, are smaller for non‐expiring options in the current expiration cycle than for non‐current expiration cycle options.
An empirical examination of the dispersion and accuracy of analyst forecasts surrounding option listing
Authors: Ho Li‐Chin Jennifer , Hassell John M. , Swidler Steve
Published: October 2002

Prior theoretical and empirical research indicates that option trading enhances the availability and timeliness of market information, and that the market's earnings expectation (belief) is influenced by characteristics of the information environment. Motivated by these research findings, we investigate whether option listing is associated with changes in the market's expectations about future earnings. Assuming that the distribution of analysts' earnings forecasts serves as a proxy for the market's earnings expectations and using I/B/E/S consensus analyst forecasts, we examine two properties of analyst forecasts: accuracy and dispersion. The results indicate that consensus analyst forecast accuracy improves after option listing and that the variability of analyst forecasts increases after option listing. The accuracy and dispersion results are somewhat weaker but still present after controlling for firm size and analyst following.
Financial variables contributing to savings and loan failures from 1980–1989
Authors: Harrison Patricia , Ragas Wade R.
Published: October 2002

This study investigates performance in the savings and loan (S&L) industry during the 1980s. Logistic regression is used to replicate the Benston (1985) study for the decade of the eighties. This study expands upon Benston's work by identifying the effects of new charters (1980 or later), and differing capital definitions (GAAP) versus RAP). The stability of the variables contributing to success or failure is also reviewed for the periods 1982–1985 and 1986–1989. The results of this study confirm the earlier findings of Benston. Net worth to total assets and return on total assets were negatively related to failure and were the only variables found to be significant in all analyses. Direct investments to total assets was not found to be significant. Further, newly chartered firms were found to be no more likely to fail than the other existing firms. There were no major differences in the statistical results when testing using the GAAP and RAP definitions of capital which suggests that regulatory changes in accounting rules did not have a major effect on firm survival.
Stimulation and inhibition of fibril formation by a peptide in the presence of different concentrations of SDS
Authors: Pertinhez Thelma A , Bouchard Mario , Smith Richard A.G , Dobson Christopher M , Smith Lorna J
Published: October 2002

Sodium dodecyl sulphate (SDS), a detergent that mimics some characteristics of biological membranes, has been found to affect significantly fibril formation by a peptide from human complement receptor 1. In aqueous solution the peptide is unfolded but slowly aggregates to form fibrils. In sub‐micellar concentrations of SDS the peptide is initially α‐helical but converts rapidly to a β‐sheet structure and large quantities of fibrils form. In SDS above the critical micellar concentration the peptide adopts a stable α‐helical structure and no fibrils are observed. These findings demonstrate the sensitivity of fibril formation to solution conditions and suggest a possible role for membrane components in amyloid fibril formation in living systems.
Regulatory expression of MDP77 protein in the skeletal and cardiac muscles
Authors: Fujimori Kazuhiro E , Uyeda Atsuko , Taguchi Takahisa
Published: October 2002

The mdp77 gene was first cloned from the cDNA library of denervated chick muscles, while its role(s) in vivo was unknown. In the present study, using specific polyclonal antibodies against MDP77, we show that MDP77 was expressed specifically in the skeletal and cardiac muscle, and confirm its presence in the cytoplasm of the extrafusal muscle fibers. In mature muscles, MDP77 immunoreactivity was observed in a repetitive manner along the sarcomere. The onset of MDP77 expression occurred just after myotube formation both in vivo and in vitro. Furthermore, MDP77 was enriched in the intrafusal muscle fibers. Our findings suggest that MDP77 plays an important role(s) in the differentiation, maturation and function of both the skeletal and cardiac muscles.
Plant dihydroorotate dehydrogenase differs significantly in substrate specificity and inhibition from the animal enzymes
Authors: Ullrich Alexandra , Knecht Wolfgang , Piskur Jure , Löffler Monika
Published: October 2002

The mitochondrial membrane bound dihydroorotate dehydrogenase (DHODH; EC 1.3.99.11) catalyzes the fourth step of pyrimidine biosynthesis. By the present correction of a known cDNA sequence for Arabidopsis thaliana DHODH we revealed the importance of the very C‐terminal part for its catalytic activity and the reason why – in contrast to mammalian and insect species – the recombinant plant flavoenzyme was unaccessible to date for in vitro characterization. Structure–activity relationship studies explained that potent inhibitors of animal DHODH do not significantly affect the plant enzyme. These difference could be exploited for a novel approach to herb or pest growth control by limitation of pyrimidine nucleotide pools.
The one‐share‐one‐vote‐rule and managerial compensation
Authors: Teall John L.
Published: October 2002

Firms listed in the United Kingdom, Sweden, Canada, Israel, and elsewhere frequently issue multiple classes of shares, while countries such as France and Italy have traditionally prohibited dual‐class capitalizations. Finland, Sweden and Denmark place restrictions on vote ratios between share classes. Several theoretical papers, notably Grossman and Hart (1988) and Harris and Raviv (1988) offer theoretical evidence for the optimality of the One‐Share‐One‐Vote rule, though the empirical evidence is mixed. The purpose of this paper is to integrate the important impact of managerial compensation into the capitalization decision. Theoretical evidence offered in this paper suggests that the opportunity to vary managerial compensation can lead to the optimality of dual‐class capitalization. Hence, there may be little merit to the regulation of multiple class capitalizations.
Landowning Bourgeoisie or Business Bourgeoisie? On the Peculiarities of the Argentine Economic Elite, 1880–1945
Authors: HORA ROY
Published: October 2002

This article examines some characteristics of the Argentine business elite between the end of the nineteenth century and the rise of peronismo in the mid-1940s. To do so, it discusses the ideas relating to this theme proposed by Jorge Sábato in his influential study, La clase dominante en la Argentina moderna. Sábato argued that diversification of assets in a wide range of operations constituted the defining aspect of the economic strategy of the late nineteenth-century and early twentieth-century entrepreneurial elite. This hypothesis requires revision. Simultaneous investment in various economic activities also characterises other entrepreneurial classes in the Americas and in Europe, and for this reason does not offer a convincing account of the peculiarities of the Argentine bourgeoisie. Sábato paid little attention to what in more traditional accounts distinguishes the Argentine proprietor class (and, in addition, the economy as a whole) from its counterparts in other parts of the world: its privileged ties to land and to rural production. However, analysis of probate records confirm this picture, especially for the turn-of-the-century elite.
Colonization, globalization and the plight of ‘weak’ languages
Authors: MUFWENE SALIKOKO S.
Published: October 2002

Daniel Nettle & Suzanne Romaine, Vanishing voices: the extinction of the world's languages. Oxford: Oxford University Press, 2000. Pp. x+241.
Population structure of the necrophagous amphipod Eurythenes gryllus (Amphipoda: Gammaridea) from the Atacama Trench (south-east Pacific Ocean)
Authors: Thurston Michael H. , Petrillo Mario , Della Croce Norberto
Published: October 2002

Baited traps deployed at 7800 m in the Atacama Trench off northern Chile, captured over 400 specimens of Eurythenes gryllus. This is the greatest depth of occurrence reported for the species. Of the 398 specimens available for study, all but three were female, giving a sex ratio very different from any reported previously. Female specimens measured 29–76 mm in length, and all were immature. Length/frequency distributions based on total length, peraeonite 1 length, and coxa 4 oostegite length were unimodal. Relationships between total length, and peraeonite 1 length, oostegite length, and wet weight were established. Oostegite development appeared to be precocious compared with published data. Subtle differences in peraeon, urosome, gnathopods, coxa 4, peraeopod 7, and epimeron 3 morphology, and the growth of oostegites separate Atacama Trench specimens from previously described material. The morphology exhibited by these specimens lies outside the known variability of E. gryllus, and suggests that this pan-oceanic entity may be undergoing incipient speciation.
Morphometry of the northern Patagonian sympatric populations of Loligo sanpaulensis and Loligo gahi
Authors: Barón Pedro J. , Ré María E.
Published: October 2002

Loligo gahi and Loligo sanpaulensis (Mollusca: Cephalopoda), two squid species presently under exploitation in the south-west Atlantic, are sympatric in coastal waters of northern Patagonia. In the present study, the morphometry of both species' northern Patagonian populations was analysed and compared. Relationships between the morphometric variables and mantle length, the standard measure of size for squids, are allometric in most cases. Weight and fin length show different rates of growth relative to mantle length in males and females of both species. Fin length, fin width and mantle length are the best morphometric variables to discriminate the mantle/fin complexes. Free rachis length, gladius length and gladius width are the most useful to separate both species' pens. The best discrimination of the tentacles is provided by the diameter of the central and marginal suckers and the number of teeth on the three largest sucker rings. Discriminant functions are provided to allow the classification of individuals from both species and the identification of pens and tentacle clubs found in predators digestive contents.
Feeding of anchovy Engraulis encrasicolus larvae in the north-west Mediterranean
Authors: Tudela S. , Palomera I. , Quílez G.
Published: October 2002

Anchovy larvae, collected at 107 stations in the north-west Mediterranean were analysed, in relation to three possible variables, the diurnal or nocturnal time of sampling, the location of sampling stations in relation to the neritic and oceanic domain, and the assignation of anchovy samples to each of the two main anchovy spawning grounds in the region. Feeding activity appeared to be mainly diurnal, stomach contents consisting mostly of copepod eggs, nauplii and copepodites. The stomachs of larger larvae showed an increase in the size range of prey, together with a parallel increase in the incidence of copepodites in the diet.
Impact of the ‘Erika’ oil spill on the Tigriopus brevicornis ecosystem at the Le Croisic headland (France): preliminary observations
Authors: Pavillon J.-F. , Oudot J. , Dlugon A. , Roger E. , Juhel G.
Published: October 2002

An investigation of the oil spill after the wreck of the tanker ‘Erika’ on 16 December 1999 showed that the maritime area around the town of Le Croisic (between the Vilaine and Loire river estuaries) was severely contaminated by the resulting black tide. Samples of sediment, oil and water were collected during several missions to the Le Croisic headland and analysed. The toxicity of the oil was tested on two organisms, the harpacticoid copepod Tigriopus brevicornis and the alga Enteromorpha intestinalis. The tests showed only slight degradation of the oil after three months. In laboratory conditions, the toxicity of the sediment contaminated by the oil was apparent on the copepod after four days of exposure. Seawater in contact with the oil also had an effect on the alga.
The sighting of pygmy killer whales (Feresa attenuata) in the southern Bay of Biscay and their association with cetacean calves
Authors: Williams A.D. , Williams R. , Brereton T.
Published: October 2002

The pygmy killer whale Feresa attenuata is a poorly understood species that occurs in tropical and warm sub-tropical waters worldwide. The true range of these animals is not well established and there have been reports of them in temperate waters of the South Atlantic and Pacific Oceans. At 1746 h on 24 April 1997 at 45°15′76″N 30°56′54″W the first of two groups of small robust cetaceans were observed by experienced cetacean observers during a survey carried out aboard the P&O Portsmouth cruise ferry ‘Pride of Bilbao’. At 1820 at position 45°25′96″N 40°00′94″W on the same day a second group of animals of this species was encountered. In both cases the cetaceans were in close proximity to cetaceans with new born or first year calves. Identification information was recorded by the observers and the animals were identified as pygmy killer whales. These records represent the first in the Bay of Biscay and the most northerly records for this species.
Band description of knots and Vassiliev invariants
Authors: TANIYAMA KOUKI , YASUHARA AKIRA
Published: October 2002

In the 1990s, Habiro defined Ck-move of oriented links for each natural number k
[5]. A Ck-move is a kind of local move of oriented links, and two oriented knots have
the same Vassiliev invariants of order [les ] k−1 if and only if they are transformed into
each other by Ck-moves. Thus he has succeeded in deducing a geometric conclusion
from an algebraic condition. However, this theorem appears only in his recent paper
[6], in which he develops his original clasper theory and obtains the theorem as a
consequence of clasper theory. We note that the ‘if’ part of the theorem is also shown
in [4], [9], [10] and [16], and in [13] Stanford gives another characterization of knots
with the same Vassiliev invariants of order [les ] k−1.
Treatment of Chronic Ischaemia of a Replanted Thumb with Iloprost
Authors: ŠABOVIC̆ M.
Published: October 2002

A 40-year-old man had chronic ischaemia of his replanted thumb. Angiography revealed occlusion of both digital arteries and weak collaterals. He was treated for 4 weeks with Iloprost which produced a definite and sustained improvement. As the digital arteries remained occluded, the beneficial effect of Iloprost was attributed to increased flow in the microcirculation and collaterals.
Failed Ulnar Head Resection: Prevention and Treatment
Authors: GARCIA-ELIAS M.
Published: October 2002

Distal ulnar head resections may cause a painful impingement of the distal ulnar stump against the radius during loaded forearm rotation. Different soft-tissue procedures have been suggested to solve this difficult problem, but none has demonstrated clear superiority over the others. The introduction of a variety of ulnar head and total radio-ulnar joint prostheses has provided a new method of addressing this problem, but there is presently no evidence that these implants produce long-lasting results. This paper critically reviews these different options, and emphasizes techniques which may help to minimize the risk of complications when excision of the ulnar head is unavoidable.
Cigar-shaped ferrite nanocrystals: Orientation of the easy magnetic axes
Authors: Ngo A. T. , Pileni M. P.
Published: October 2002

Mesoscopic structures made of cigar-shaped γ-Fe2O3 nanocrystals with an average length of 325 nm and aspect ratio of 7 are described. The structures were prepared starting from an aqueous solution to which a magnetic field parallel to the substrate could be applied during the evaporation process. If a magnetic field was applied, the nanocrystals rotated their long axis along the magnetic field direction to form ribbons, whereas without a field the nanocrystals remained deposited on the substrate with a random orientation. The orientation of the nanocrystals is responsible for the anisotropy of the ribbons as evidenced by the hysteresis loops.
Growth and transport of clusters in thermal plasma vapor deposition of silicon
Authors: Han P. , Yoshida T.
Published: October 2002

Numerical simulation is conducted for Si cluster growth and transport processes during ultrafast deposition of microcrystalline Si for solar cell fabrication by thermal plasma chemical vapor deposition. Within the boundary layer just above the substrate, Si vapor is supersaturated during the quenching process, leading to the generation of Si clusters of various sizes under the effects of coagulation and evaporation. The transport process of these Si clusters within the plasma gas flow is investigated numerically by the continuum approach, taking into account convection and diffusion phenomena of clusters. The thermophoretic effects on cluster transport in terms of the deposition efficiency and the film growth rate are also investigated. It is found that the clusters in the nanosize range (<1 nm) are the dominant component among the deposition species and that the thermophoretic force FT is a highly crucial factor for achieving the high film growth rate of above 100 nm/s and high deposition efficiency of around 85%.
Electronic structures of promising photocatalysts InMO4 (M=V, Nb, Ta) and BiVO4 for water decomposition in the visible wavelength region
Authors: Oshikiri Mitsutake , Boero Mauro , Ye Jinhua , Zou Zhigang , Kido Giyuu
Published: October 2002

The compounds InMO4 (M=V, Nb, Ta) and BiVO4 are promising photocatalysts which are able to induce hydrolysis of water molecules under visible light irradiation. By first principles calculations, supported by experiments, we inspect their peculiar electronic structure in an attempt to rationalize the link between the bulk crystal architecture of the materials and the related electronic properties. We find that the bottom of the conduction band of InMO4 systems consists of a large contribution (about 20%) due to 5s orbitals of In atoms. Another dominant component comes from d orbitals of V, Nb, and Ta. On the other hand, the top of the valence band of the BiVO4 shows a contribution from 6s orbitals of Bi of about 18% as well as a dominant component due to 2p states of O. We can infer that the photocatalytic activity could be improved by the large mobility coming from the s orbital component as well as by tuning the electron affinity (position of the bottom of the conduction band) and ionization potential (top of the valence band). The absorption process of a H2O molecule in the InVO4 system was studied by fully relaxing the structure via first principles calculations. Our simulations have shown that the lone pairs of the O atom belonging to the H2O molecule have a strong tendency to bind to In, while, at the same time, at least one of the H atoms of the water molecule forms a hydrogen bond with the O of the InVO4 catalyst surface. When a water molecule absorption occurs, it induces a shortening of the In–In and In–V bond lengths around at the surface layer. This might suggest that the electron mobility is locally enhanced due to the resulting larger orbital overlap of In_5s–In_5s and In_5s–V_3d with respect to the case of absence of water.
Photoinduced Faraday effect in a cobalt-iron polycyanide film
Authors: Sato Yusuke , Ohkoshi Shin-ichi , Hashimoto Kazuhito
Published: October 2002

We report on a photoinduced Faraday effect in an electrochemically synthesized cobalt-iron polycyanide film. When the Na0.36Co1.36[Fe(CN)6] ⋅4.7H2O film was irradiated with light from a Xe lamp, the Faraday rotation (FR) and Faraday ellipticity (FE) effects emerge suddenly over the 400–800 nm spectral change. The FR angle changed from 0° to −800° cm−1 at 530 nm although only 30% of the absorption coefficient changed (11×103→7.7×103 cm−1). After illumination, magnetic hysteresis loops were also observed in FR and FE spectra; The coercive field was 3 kOe. The present Faraday effect was caused by the photoinduced spin transition from the paramagnetic CoIII (S=0)−NC−FeII (S=0) phase to the ferromagnetic CoII (S=3/2)−NC−FeIII (S=1/2) phase. In addition, the observed transition in the Faraday spectra was assigned to the intervalence transfer band between CoII and FeIII through a cyano bridge.
Electronic and geometric structures of Co2Cn− and V2Cn−: Initial growth mechanisms of late and early 3d transition-metal carbide clusters
Authors: Tono Kensuke , Terasaki Akira , Ohta Toshiaki , Kondow Tamotsu
Published: October 2002

Photoelectron spectra of Co2Cn− (n=2, 3) and V2Cn− (n=2–4) were measured in the energy range below 3 eV. Analyses of these spectra by the density-functional theory deduced their electronic states and geometric structures. The growth mechanisms of the 3d transition-metal carbide clusters were discussed on the basis of the structural models obtained. The geometric structures of Co2Cn− exhibit a tendency that carbon atoms aggregate to form a Cn substructure. In contrast, V2Cn− consists of VC2 building blocks, which prelude the formation of a vanadium-carbide network. These features illustrate the differences in the carbide-formation processes of the late and the early 3d transition metals, that is, only the latter forms large metal-carbide networks such as metallocarbohedrens and metal carbide compounds.
Thickness determination of very thin SiO2 films on Si by electron-induced x-ray emission spectroscopy
Authors: Hombourger C. , Jonnard P. , Filatova E. O. , Lukyanov V.
Published: October 2002

Electron-induced x-ray emission spectroscopy (EXES) associate with a semi-empirical electron scattering model is used to determine thicknesses between 2 and 21 nm of SiO2 films on Si. The small charging effect occurring upon electron irradiation is taken into account by introducing a retarding potential in the model. The results are in very close agreement with those obtained by spectroscopic ellipsometry and x-ray reflectometry. It is demonstrated that the EXES with its model is a well-suited method for the quantitative analysis of thin insulating films with an uncertainty lower than 5%.
Ion transport and crystallization in inorganic building materials as studied by nuclear magnetic resonance
Authors: Pel Leo , Huinink Henk , Kopinga Klaas
Published: October 2002

Salt weathering is a major cause of deterioration of buildings and monuments of cultural heritage. We have determined the underlaying moisture and ion transport within a representative building material by measuring the time evolution of NaCl-saturated samples during one-sided drying using nuclear magnetic resonance. The measured NaCl concentration profiles reflect the competition between advection to the surface and redistribution by diffusion. By representing the measured moisture and NaCl profiles in an efflorescence pathway diagram (EPD) the crystallization is also taken into account. The pathways followed in the EPD indicate that for historical objects in general, crystallization at the surface cannot be avoided.
Thermal and doping dependence of 4H-SiC polytype transformation
Authors: Brillson L. J. , Tumakha S. , Jessen G. H. , Okojie R. S. , Zhang M. , Pirouz P.
Published: October 2002

We have observed characteristic temperatures, anneal times, and doping densities that lead to stacking faults and 3C-SiC-like bands in 4H-SiC epilayers. Low energy cathodoluminescence spectroscopy measurements reveal a temperature threshold of 800 °C for emergence of these features in thermally oxidized or argon annealed 4H-SiC with an activation energy ≈2.5 eV. Stacking fault generation and polytype transformation exhibits a strong doping dependence, appearing only in a range of highly doped n-type 4H-SiC. Systematics of these strain and/or electronic effects induced by high N concentrations can be used to control structural instabilities during SiC device fabrication.
Impurity incorporation in InGaN grown by rf plasma-assisted molecular beam epitaxy
Authors: Poblenz C. , Mates T. , Craven M. , DenBaars S. P. , Speck J. S.
Published: October 2002

Impurity incorporation into InGaN films grown by rf-plasma assisted molecular beam epitaxy was investigated using secondary ion mass spectroscopy. A factor of 3 increase in both oxygen and boron incorporation into InGaN films relative to GaN films at 600 °C was demonstrated, and a factor of 10 increase in oxygen relative to the detectable base line in GaN grown under optimal conditions. Oxygen incorporation is related specifically to the different structures of the gallium and indium wetting layers on the growth surface. It is also shown using secondary ion mass spectroscopy that the formation of the gallium wetting layer during GaN growth is disrupted by the presence of excess indium; increased oxygen incorporation was observed during growth with an incomplete gallium wetting layer and indium on the growth surface. This study demonstrates the profound impact of surface atomic structure on impurity incorporation and reveals the protective nature of the gallium wetting layer as compared to the indium wetting layer during growth by rf-plasma assisted molecular beam epitaxy.
Enhanced third-order nonlinear optical properties of C60–silane compounds
Authors: Yu B. L. , Xia H. P. , Zhu C. S. , Gan F. X.
Published: October 2002

The nonlinear optical properties of C60[NH2–(CH2)3–Si(OC2H5)3]3 sol and gel were investigated by femtosecond optical Kerr gate technique at 820 nm. The nonresonant third-order optical susceptibilities were measured to be 1.4×10−13 and 1.6×10−13 esu for the C60[NH2–(CH2)3–Si(OC2H5)3]3 sol and gel, respectively, which are two orders larger than that of C60 molecule.
Role of cytokines and nitric oxide in the induction of tuberculostatic macrophage functions
Authors: Petricevich Vera L. , Alves Rosely C. B.
Published: October 2002

The aim of this study was to determine phenotypic differences when BCG invades macrophages. Bacilli prepared from the same BCG primary seed, but produced in different culture media, were analysed with respect to the ability to stimulate macrophages and the susceptibility to treatment with cytokines and nitric oxide (NO). Tumour necrosis factor (TNF) activity was assayed by measuring its cytotoxic activity on L‐929 cells, interleukin‐6 (IL‐6) and interferon γ (IFN‐γ) were assayed by enzyme‐linked immunosorbent assay (ELISA), whereas NO levels were detected by Griess colorimetric reactions in the culture supernatant of macrophages incubated with IFN‐γ , TNF or NO and subsequently exposed to either BCG‐I or BCG‐S. We found that BCG‐I and BCGS bacilli showed different ability to simulate peritoneal macrophages. Similar levels of IL‐6 were detected in stimulated macrophages with lysate from two BCG samples. The highest levels of TNF and IFN‐γ were observed in macrophages treated with BCG‐S and BCG‐I, respectively. The highest levels of NO were observed in cultures stimulated for 48h with BCG‐S. We also found a different susceptibility of the bacilli to ex ogenous treatm ent w ith IFN‐γ and TNF which were capable of killing 60 and 70% of both bacilli, whereas NO was capable of killing about 98 and 47% of BCG‐I and BCG‐S, respectively. The amount of bacilli proportionally decreased with IFN‐γ and TNF, suggesting a cytokine‐related cytotox ic effect. Moreover, NO also decreased the viable number of bacilli. Interestingly, NO levels of peritoneal macrophages were significantly increased after cytokine treatment. This indicates that the treatment of macrophages with cytokines markedly reduced bacilli number and presented effects on NO production. The results obtained here emphasize the importance of adequate stimulation for guaranteeing efficient killing of bacilli. In this particular case, the IFN‐γ and TNF were involved in the activation of macrophage bactericidal activity.
IL‐12, IL‐6 and IFN‐γ production by lymphocytes of pregnant women with rheumatoid arthritis remission during pregnancy
Authors: Tchórzewski Henryk , Krasomski Grzegorz , Biesiada Lidia , Głowacka Ewa , Banasik Małgorzata , Lewkowicz Przemysław
Published: October 2002

Background: Rheumatoid arthritis (RA) is an autoimmune disease with progressive activity. The RA remission was observed in women during pregnancy, but the mechanism responsible for remission is hypothetical only and concerns mechanisms of immune regulation such as lymphocyte subpopulations and interleukin production.

Aims: The lymphocyte subpopulations and interleukin production in vitro in a group of healthy nonpregnant women, healthy pregnant women and pregnant women suffering from RA may help towards a better understanding of regulation of the immune processes.

Methods: The investigations were performed in trimester III – 2 days after delivery and 6 weeks after delivery. Peripheral blood lymphocytes were isolated on Gradisol gradient and analysed immediately or after having been cultured for 72 hours in RPMI medium supplemented with 10% FCS. The cultures were terminated after 72 h, supernatants stored at –72°C for interleukin evaluation. The concentrations of IFN‐γ, IL‐2, IL‐6, IL‐12,
TNF‐α and its soluble receptors R‐I, R‐II were estimated in non‐stimulated and PHA (Sigma, 5 μg/ml) stimulated culture supernatants using ELISA Endogen kits according to the manufacturer’s instructions.

Results: The general pattern of T cell subpopulation distribution was similar in all analysed groups. Decreased IFN‐γ, IL‐12 and increased IL‐6 production by lymphocytes after PHA stimulation was found in trimester III in pregnant women with RA as compared to healthy pregnant woman.

Conclusion: The obtained results suggest that in pregnant women with RA the TH1 cell response predominates, contrary to healthy pregnant women with TH2 type functional response. These phenomena were not observed after delivery.
Nicotine reversal effects of the benzoflavone moiety from Passiflora incarnata Linneaus in mice
Authors: Dhawan Kamaldeep , Kumar Suresh , Sharma Anupam
Published: October 2002

A benzoflavone moiety (BZF) has recently been reported to be liable for many of the biological effects of the plant Passiflora incarnata Linneaus. In light of various reports mentioning the usefulness of P. incarnata in tobacco addiction, studies have been performed using four doses (1, 5, 10 and 20 mg/kg) of the bioactive BZF moiety isolated from the aerial parts of P. incarnata . In a 7‐day experimental regimen, mice (n = 5) were given nicotine hydrogen tartrate (2 mg/kg), and combinations of nicotine with four doses of BZF (NnP‐1, NnP‐5, NnP‐10 and NnP‐20) q.i.d. by the s.c. route. At the end of the 7 days of treatment, naloxone was given to the mice from all groups to induce a nicotine withdrawal syndrome.The mice that had been treated with 10 and 20 mg/kg dose of BZF concurrently with nicotine showed a significantly fewer number of withdrawal jumps relative to the group treated with nicotine alone (Nn group). Separately, in a 14‐day treatment regimen, mice (n = 10; for the N group, n = 12) were administered nicotine (2 mg/kg) and combinations of nicotine with four doses of BZF (NP‐1, NP‐5, NP‐10, NP‐20 groups) q.i.d. by the s.c. route. Spontaneous physical and behavioural signs of nicotine dependence were observed 3 hours after cessation of treatments on the 14th day. Mice administered with combinations of nicotine and 5, 10 and 20 mg/kg doses of BZF (i.e. NP‐5, NP10 and NP‐20 groups), exhibited less intensity and severity of withdrawal effects compared to the mice treated with nicotine alone. Those mice treated with the two highest doses of BZF,in combination with nicotine (NP‐10 and NP‐20), showed significantly fewer nicotine‐abstinence withdrawal jumps and normal ambulatory behaviour. BZF treatment prevented weight loss and resulted in normal performance in the swimming endurance test, which may be a measure of stress and/or depression. Similarly, acute administration of a single 20 mg/kg dose of BZF prevented some of the nicotine‐withdrawal effects; lower doses were almost inert. These studies, although preliminary, suggest that the BZF may have value in treating nicotine addiction.
Judging the Quality of Gene Expression-Based Clustering Methods Using Gene Annotation
Authors: Gibbons Francis D. , Roth Frederick P.
Published: October 2002

We compare several commonly used expression-based gene clustering algorithms using a figure of merit based on the mutual information between cluster membership and known gene attributes. By studying various publicly available expression data sets we conclude that enrichment of clusters for biological function is, in general, highest at rather low cluster numbers. As a measure of dissimilarity between the expression patterns of two genes, no method outperforms Euclidean distance for ratio-based measurements, or Pearson distance for non-ratio-based measurements at the optimal choice of cluster number. We show the self-organized-map approach to be best for both measurement types at higher numbers of clusters. Clusters of genes derived from single- and average-linkage hierarchical clustering tend to produce worse-than-random results.

[The algorithm described is available at http://llama.med.harvard.edu, under Software.]
Maize Opaque Endosperm Mutations Create Extensive Changes in Patterns of Gene Expression[W]
Authors: Hunter Brenda G. , Beatty Mary K. , Singletary George W. , Hamaker Bruce R. , Dilkes Brian P. , Larkins Brian A. , Jung Rudolf
Published: October 2002

Maize starchy endosperm mutants have kernel phenotypes that include a brittle texture, susceptibility to insect pests, and inferior functional characteristics of products made from their flour. At least 18 such mutants have been identified, but only in the cases of opaque2 (o2) and floury2 (fl2), which affect different aspects of storage protein synthesis, is the molecular basis of the mutation known. To better understand the relationship between the phenotypes of these mutants and their biochemical bases, we characterized the protein and amino acid composition, as well as the mRNA transcript profiles, of nearly isogenic inbred lines of W64A o1, o2, o5, o9, o11, Mucuronate (Mc), Defective endosperm B30 (DeB30), and fl2. The largest reductions in zein protein synthesis occur in the W64A o2, DeB30, and fl2 mutants, which have ∼35 to 55% of the wild-type level of storage proteins. Zeins in W64A o5, o9, o11, and Mc are within 80 to 90% of the amount found in the wild type. Only in the cases of o5 and Mc were significant qualitative changes in zein synthesis observed. The pattern of gene expression in normal and mutant genotypes was assayed by profiling endosperm mRNA transcripts at 18 days after pollination with an Affymetrix GeneChip containing >1400 selected maize gene sequences. Compared with W64A sugary1, a mutant defective in starch synthesis, alterations in the gene expression patterns of the opaque mutants are very pleiotropic. Increased expression of genes associated with physiological stress, and the unfolded protein response, are common features of the opaque mutants. Based on global patterns of gene expression, these mutants were categorized in four phenotypic groups as follows: W64A+ and o1; o2; o5/o9/o11; and Mc and fl2.
Theoretical and experimental investigations on coherence of traffic noise transmission through an open window into a rectangular room in high-rise buildings
Authors: Zhang Jiping , Jiang Weikang , Li Ningrong
Published: October 2002

A method for theoretically calculating the coherence between sound pressure inside a rectangular room in a high-rise building and that outside the open window of the room is proposed. The traffic noise transmitted into a room is generally dominated by low-frequency components, to which active noise control (ANC) technology may find an application. However, good coherence between reference and error signals is essential for an effective noise reduction and should be checked first. Based on traffic noise prediction methods, wave theory, and mode coupling theory, the results of this paper enabled one to determine the potentials and limitations of ANC used to reduce such a transmission. Experimental coherence results are shown for two similar, empty rectangular rooms located on the 17th and 30th floors of a 34 floor high-rise building. The calculated results with the proposed method are generally in good agreement with the experimental results and demonstrate the usefulness of the method for predicting the coherence.
Iterative reconstruction algorithm for optoacoustic imaging
Authors: Paltauf G. , Viator J. A. , Prahl S. A. , Jacques S. L.
Published: October 2002

Optoacoustic imaging is based on the generation of thermoelastic stress waves by heating an object in an optically heterogeneous medium with a short laser pulse. The stress waves contain information about the distribution of structures with preferential optical absorption. Detection of the waves with an array of broadband ultrasound detectors at the surface of the medium and applying a backprojection algorithm is used to create a map of absorbed energy inside the medium. With conventional reconstruction methods a large number of detector elements and filtering of the signals are necessary to reduce backprojection artifacts. As an alternative this study proposes an iterative procedure. The algorithm is designed to minimize the error between measured signals and signals calculated from the reconstructed image. In experiments using broadband optical ultrasound detectors and in simulations the algorithm was used to obtain three-dimensional images of multiple optoacoustic sources. With signals from a planar array of 3×3 detector elements a significant improvement was observed after about 10 iterations compared to the simple radial backprojection. Compared to conventional methods using filtered backprojection, the iterative method is computationally more intensive but requires less time and instrumentation for signal acquisition.
Effects of incoherent and coherent source spectral information in geoacoustic inversion
Authors: Dosso Stan E. , Wilmut Michael J.
Published: October 2002

This paper examines the effect on matched-field geoacoustic inversion of including source spectral information, as can be available in controlled-source acoustic surveys. Source information can consist of relative or absolute knowledge of the source amplitude and/or phase spectra, and can allow frequency-coherent processing of spatial acoustic-field data. A number of multi-frequency acoustic processors, appropriate for specific types of source information, are defined based on the likelihood function for complex acoustic-field data with Gaussian noise. The information content of the various processors is quantified in terms of marginal probability distributions and highest-probability density intervals for the unknown geoacoustic and geometric parameters, which define the accuracy expected in inversion. Marginal distributions are estimated using a fast Gibbs sampler approach to Bayesian inversion, which provides an efficient, unbiased sampling of the multi-dimensional posterior probability density. The analysis is illustrated for incoherent and coherent processors corresponding to several types of source knowledge ranging from complete information to no information, and the results are considered as a function of the spatial and frequency sampling of the acoustic fields.
A new 1-D integral representation for dynamic response of anisotropic elastic solids due to a point force
Authors: Wu Kuang-Chong
Published: October 2002

A new 1-D integral is presented for calculating the transient response due to a suddenly applied point force in a general anisotropic solid. The integral is based on a 2-D solution for a line force. It is shown that the integral reduces to a simple expression for the static Green’s function immediately after the passage of the last bulk wave. The computational efficiency and accuracy of the proposed formulation are demonstrated by numerical examples for zinc and copper.
Novel active noise-reducing headset using earshell vibration control
Authors: Rafaely Boaz , Carrilho Joao , Gardonio Paolo
Published: October 2002

Active noise-reducing (ANR) headsets are available commercially in applications varying from aviation communication to consumer audio. Current ANR systems use passive attenuation at high frequencies and loudspeaker-based active noise control at low frequencies to achieve broadband noise reduction. This paper presents a novel ANR headset in which the external noise transmitted to the user’s ear via earshell vibration is reduced by controlling the vibration of the earshell using force actuators acting against an inertial mass or the earshell headband. Model-based theoretical analysis using velocity feedback control showed that current piezoelectric actuators provide sufficient force but require lower stiffness for improved low-frequency performance. Control simulations based on experimental data from a laboratory headset showed that good performance can potentially be achieved in practice by a robust feedback controller, while a single-frequency real-time control experiment verified that noise reduction can be achieved using earshell vibration control.