bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface morphology, elemental distribution,
and spectroscopic changes subsequent the
application of nanosecond pulsed Nd:YAG
laser on dental enamel surface
Authors: Antunes A , Vianna S S , Gomes A S L , de Rossi W , Zezell D M
Published: November 2004

Application and development of new methods in caries
prevention is of paramount importance to reduce the incidence of
chronic cases of the caries disease and to preserve dental
structure. In this work, we tested nanosecond pulsed Nd:YAG laser
on enamel surface examining the changes laser-induced by means
SEM, EDS, and FTIR. SEM revealed, the existence of melted zone and
bubble inclusions when 40 J/cm2 (τ=6 ns, 5 Hz) was
applied on human sound enamel surface. The morphological
alteration to 10 J/cm2 (τ=6 ns, 5 Hz) and to
20 J/cm2 (τ=200 ns, 7 Hz) no presented melting aspect,
but a greater number of bubble inclusions. We have indicated that
the Ca/P ratio increased to irradiation conditions employed here.
In our previous study, the combination of the laser parameters not
produce an excessive increase in temperature. The temperature
variation was less than 2.5°C in the dental pulpal,
following application of the energy density of 40 J/cm2. Our
results suggest that nanosecond pulsed Nd:YAG laser can be used to
obtain minimal morphological alteration associated with a
chemical reorganization enhancing the microhardness values and
consequently inhibiting the acid dissolution by bacterial agents.
In this work, the Vickers microhardness was quantified. Our
results of FTIR analysis indicated that the laser effects
occurring substantially in the organic compounds (such as water
and proteins groups) and are reduced for mineral contend (such as
phosphate and carbonate groups).
Post‐Crosslinkable Blends: Reactions Between a Linear Poly(hydroxyl‐amino ether) and a Diepoxy
Authors: Constantin François , Fenouillot Françoise , Pascault Jean‐Pierre , Williams Roberto Juan Jose
Published: November 2004

Summary: A thermoplastic poly(hydroxyl‐amino ether) polymer (BLOX) was blended with a diglycidyl ether of bisphenol A monomer (DGEBA). This system may be used as a crosslinkable thermoplastic. It means that it may be processed in an extruder like a classic thermoplastic, and cured by etherification reactions initiated by tertiary amine groups of the BLOX in a second step, to produce a material with good mechanical properties. In order to understand and quantify the etherification reactions occurring at high temperature (135 °C), between epoxy groups of the diepoxy and hydroxyl groups of the thermoplastic, a model system was studied based on DGEBA in excess and ethanolamine. In the model system the rate of the etherification reaction was well described by a second‐order kinetic equation. The specific rate constants and the epoxy conversion at the gel were related to the polarity of the reactive medium. The polyetherification occurring in the DGEBA‐BLOX system could also be fitted with a second‐order kinetics. A significant increase in the reaction rate was observed when using high BLOX concentrations.

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Gliding motion of bacteria on power‐law slime
Authors: Wang Yongqi , Hayat Tasawar , Siddiqui Abdul Majeed
Published: November 2004

The present investigation deals with an undulating surface model for the motility of bacteria gliding on a layer of non‐Newtonian slime. The slime being the viscoelastic material is considered as a power‐law fluid. A hydrodynamical model of motility involving an undulating cell surface which transmits stresses through a layer of exuded slime to the substratum is examined. The non‐linear differential equation resulting from the balance of momentum and mass is solved numerically by a finite difference method with an iteration technique. The manner in which the various exponent values of the power‐law flow affect the structure of the boundary layer is delineated. A comparison is made of the power‐law fluid with the Newtonian fluid. For the power‐law fluid with respect to different power‐law exponent values, shear‐thinning and shear‐thickening effects can be observed, respectively. Copyright © 2004 John Wiley & Sons, Ltd.
Molecular monitoring of environmental conditions influencing the induction of ochratoxin A biosynthesis genes in Penicillium nordicum
Authors: Geisen Rolf
Published: November 2004

A real‐time polymerase chain reaction (PCR) system specific for the ochratoxin A polyketide synthase gene (otapksPN) of Penicillium nordicum has been used to analyze environmental conditions, influencing the induction of that key gene of the ochratoxin A biosynthetic pathway. Generally, the induction of that gene coincides very well with the biosynthesis of ochratoxin A, demonstrating that its induction can be used as a molecular signal to monitor ochratoxin A production. It could be shown, that the expression of the otapksPN gene is greatly dependent on the media used. In YES medium expression is highest, followed by minimal medium which support ochratoxin A production and minimal medium which suppresses ochratoxin A production. The amount of ochratoxin A produced shows the same tendency. The amount produced is highest on YES medium and decreases successively to the two minimal media. The system was also used to determine the influence of environmental parameters like temperature, pH and NaCl concentration on the expression of the otapksPN gene and on ochratoxin A production in parallel. It could be shown that under acidic conditions, below pH 5.0, the expression of the otapksPN gene as well as the ochratoxin A concentration were reduced. In case of salt concentration again both measures coincide, having both highest values at increasing NaCl concentrations. In case of the temperature, however, expression of the otapksPN gene was uncoupled to ochratoxin A production. The expression was high at all temperatures tested, however, clear differences in the biosynthesis of ochratoxin A by P. nordicum could be observed at the different temperatures, showing highest production at 25°C. The importance of these data are discussed with reference to the natural habitat of P. nordicum.
Nature times nurture: How organizations can optimize their people's contributions
Authors: Erickson Bill
Published: November 2004

Leaders and managers have turned to science to devise better ways of developing high‐performance organizations. The author, however, cautions against being misled by oversimplified perspectives in the long‐running “nature versus nurture” debate over what determines human behavior. He contends the truth is really more complex, and it can point the way to more effective people management solutions once we know—with the help of good science—the real “changeables” and “unchangeables” in employee behavior. He provides two examples of solutions—better hiring/selection practices and improving employee engagement— that, when aided by science, yield a high return on investment for the companies that adopt them. © 2004 Bill Erickson
Roche group's sales organization models long‐term sales force effectiveness
Authors: Grossman Steven H. , Cotton Rodney D.
Published: November 2004

Recent studies of high‐performing sales organizations reveal that five characteristics help these organizations stay ahead of the pack. And the secrets of their long‐term success aren't what you might expect. The Diabetes Care Hospital Group of Roche Diagnostics, not in a growth industry, redesigned its sales effort by applying those characteristics—and grew their business. © 2004 Wiley Periodicals, Inc.
Granulocyte‐derived elastase and gelatinase B are required for dermal–epidermal separation induced by autoantibodies from patients with epidermolysis bullosa acquisita and bullous pemphigoid
Authors: Shimanovich Iakov , Mihai Sidonia , Oostingh Gertie J , Ilenchuk T Toney , Bröcker Eva‐B , Opdenakker Ghislain , Zillikens Detlef , Sitaru Cassian
Published: November 2004

Epidermolysis bullosa acquisita (EBA) and bullous pemphigoid (BP) are two clinically and immunologically distinct autoimmune subepidermal blistering skin diseases associated with IgG autoantibodies against the dermal–epidermal junction. BP antibodies are directed against the hemidesmosomal antigens BP180 and BP230, and those in patients with EBA target type VII collagen, a major component of anchoring fibrils. While the pathogenetic mechanisms of subepidermal blistering in BP have been previously studied using a passive transfer mouse model, the effector pathways of blister formation in EBA are largely unknown. Autoantibodies to type VII collagen and BP180 have recently been shown to induce leucocyte‐mediated subepidermal cleavage in cryosections of human skin. The aim of the present study was to identify human leucocyte protease(s) instrumental in dermal–epidermal separation induced by autoantibodies to type VII collagen and BP180. When incubated with cryosections of human skin pretreated with IgG from patients with EBA or BP but not from patients with anti‐laminin 5 mucous membrane pemphigoid or healthy controls, granulocytes were recruited to the dermal–epidermal junction and induced subepidermal splits. A combination of broad‐range protease inhibitors as well as inhibitors of serine and matrix metalloproteases completely abolished dermal–epidermal separation induced by EBA or BP autoantibodies. When characterizing the proteases involved more specifically, selective inhibition of human leucocyte elastase or gelatinase B/MMP‐9 was also found to result in suppression of blistering. These findings strongly suggest that elastase and gelatinase B are essential for granulocyte‐mediated proteolysis resulting in dermal–epidermal separation in EBA and BP patients' skin. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Solution proprieties of dendritic triazine/poly(ethylene glycol)/dendritic triazine block copolymers
Authors: Namazi Hassan , Adeli Mohsen
Published: November 2004

Dendritic–linear–dendritic triblock copolymers based on poly(ethylene glycol) (PEG) as the core and dendritic triazine blocks were synthesized. The micellar and aggregation characteristics of the compounds were investigated with NMR and fluorescence spectroscopy. The NMR investigations were carried out in a variety of solvents. In those solvents in which both moieties of the linear–dendritic compounds were completely soluble, the NMR spectra of the linear–dendritic compounds were in the normal form, and all of the signals were as expected. However, in other solvents in which one of the moieties of the compounds was not very soluble, the NMR spectra of the compounds were not in the normal form, and some of the signals were broad or disappeared. The results could be related to the aggregation behavior of the block copolymers with extended or packed conformations of PEG in the solvents, as previously observed in similar systems. Also, fluorescence investigations of some of the isolated compounds in aqueous solutions displayed micellar behavior. The critical micelle concentrations of the copolymers were determined with a fluorescence technique. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 28–41, 2005
Synthesis of nanocylinders consisting of graft block copolymers by the photo‐induced ATRP technique
Authors: Ishizu Koji , Kakinuma Hirokazu
Published: November 2004

Photoinduced atom transfer radical polymerizations (ATRP) of t‐butyl methacrylate (BMA) were carried out, initiated by model initiator benzyl N,N‐diethyldithiocarbamate (BDC) in the presence of CuCl/bipyridine (bpy) under UV irradiation. We performed the first‐order time‐conversion plots in this polymerization system, and the straight line in the semilogarithmic coordinates indicated a first‐order in the monomer. The molecular weight of poly(t‐butyl methacrylate) (PBMA) increased in direct proportion to monomer conversion. The molecular weight distribution (Mw/Mn) of PBMA was about 1.3. The initiator efficiency, f, was close to 1.0, which indicated that no side reactions occurred. A copper complex, CuCl/bpy, reversibly activated the dormant polymer chains via a N,N‐diethyldithiocarbamate (DC) transfer reaction such as Cu(DC)Cl/bpy, and it was dynamic equilibrium that was responsible for the controlled behavior of the polymerization of BMA. On the basis of this information, we established a preparation method of nanocylinders consisting of graft block copolymers by grafting from photoinduced ATRP of multifunctional polystyrene having DC pendant groups with vinyl monomers [first monomer, BMA; second monomer, styrene or methyl methcrylate (MMA)]. We have carried out the characterization of such nanocylinders in detail. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 63–70, 2005
Structure and properties of polyethylene prepared via low‐frequency vibration‐assisted injection molding
Authors: Youbing Li , Yongheng Liao , Xueqin Gao , Yi Yuan , Wenti Ke , Kaizhi Shen
Published: November 2004

A self‐made low‐frequency vibration‐assisted injection‐molding (VAIM) device was adopted to explore the relationship between mechanical property and morphology for high‐density polyethylene injected moldings. The main processing variables for the VAIM are vibration frequency and vibration pressure amplitude, and tensile properties and morphology were investigated under different VAIM processing conditions with conventional injection molding for comparison. The moldings prepared by VAIM exhibit a very well defined laminated morphology composed of a layered structure with enhanced crystallinity. Increased with vibration frequency at constant vibration pressure amplitude, the shish‐kebab structure is exhibited in the shear layer of the specimen prepared by VAIM, whereas row nucleation lamella exists in the same layer produced by enhanced vibration pressure amplitude at a constant vibration frequency. These oriented structures and enhanced crystallinity, confirmed by scanning electron microscopy, wide‐angle X‐ray diffraction, and differential scanning calorimetry, serve to obtain stronger injection moldings. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 13–21, 2005
Effect of chlorpyrifos and monocrotophos on locomotor behaviour and acetylcholinesterase activity of subterranean termites, Odontotermes obesus
Authors: Venkateswara Rao J , Parvathi K , Kavitha P , Jakka NM , Pallela R
Published: November 2004

The acute toxicity of chlorpyrifos and monocrotophos to subterranean termites, Odontotermes obesus (Rambur), has been studied by a paper contact method. The LC50 values for chlorpyrifos and monocrotophos were 0.046 and 0.148 µg cm−2, respectively. Chlorpyrifos was 3.22‐fold more toxic than monocrotophos. The effect of the pesticides on locomotor behaviour (velocity) and head acetylcholinesterase (AChE: EC 3.1.1.7) activity was estimated in LC50‐exposed termites at intervals of 4, 8, 12, 16, 20 and 24 h. Chlorpyrifos‐ and monocrotophos‐treated termites showed, respectively, 97 and 88% reduction in locomotor behaviour (velocity) after 24 h. At all time intervals the chlorpyrifos‐treated termites exhibited more AChE inhibition and showed greater distorted behaviour than those exposed to monocrotophos. In vitro studies indicated that the I50 value (50% inhibition) for chlorpyrifos against AChE was 8.75 times that of monocrotophos. Copyright © 2004 Society of Chemical Industry
Site‐specific carbohydrate profiling of human transferrin by nano‐flow liquid chromatography/electrospray ionization mass spectrometry
Authors: Satomi Yoshinori , Shimonishi Yasutsugu , Hase Toshiharu , Takao Toshifumi
Published: November 2004

Glycopeptides derived from a lysylendopeptidase digest of commercially available human transferrin were analyzed by nano‐flow liquid chromatography/electrospray ionization mass spectrometry (LC/ESI‐MS), which permitted the carbohydrate profiles at Asn432 and Asn630 to be determined. Both are located in a well‐known motif for N‐glycosylation, Asn‐Xaa‐Ser/Thr. The contents of the carbohydrates at each site were significantly different from each other, and consisted of a variety of minor types of oligosaccharides in addition to the major one, a biantennary complex‐type oligosaccharide. Nano‐flow ESI tandem mass spectrometry (MS/MS) of the glycopeptides (Cys421‐Lys433 and Ile619‐Lys646) containing these two sites yielded predominantly ions originating from the non‐reducing termini (oxonium ions) and reducing terminus, resulting from cleavage of the glycosidic bonds of the carbohydrate moieties; this permitted the structural read‐out of a small minority of the carbohydrate moieties. In particular, the observation of oxonium ions at m/z 512.2 and 803.2 is useful for probing outer non‐reducing terminal fucosylation, which represented carbohydrate structures consisting of Hex, dHex, and HexNAc, and NeuNAc, Hex, dHex, and HexNAc, respectively, from which the Lewis X structure (Galβ1‐4(Fucα1‐3)GlcNAc) was readily deduced. Moreover, fucosylation at the reducing‐terminal GlcNAc (Fucα1‐6GlcNAc) specifically occurred at Asn630, as demonstrated by treatment of the glycopeptides with α1‐3/4‐L‐fucosidase. Copyright © 2004 John Wiley & Sons, Ltd.
Nutritional recovery does not reverse the activation of brain serotonin synthesis in the ontogenetically malnourished rat
Authors: Manjarrez G.G. , Magdaleno V.M. , Chagoya G. , Hernández‐r J.
Published: November 2004

In the present work we confirm that gestational malnutrition affects body and brain composition and results in an activation of the synthesis of the brain neurotransmitter 5‐hydroxytryptamine. These results also demonstrate more activity of the rate‐limiting enzyme tryptophan hydroxylase in the malnourished fetal and postnatal brain. However, the activity of this enzyme remains increased in the brain of nutritionally recovered animals accompanied by an increase in the synthesis of 5‐hydroxytryptamine. We therefore suggest that, in the nutritionally recovered animal, the mechanism of activation of this biosynthetic path in the brain may be not dependent on the increased availability of free l‐tryptophan observed in malnourished animals, but might be due to a specific change in the enzyme complex itself. This hypothesis is supported by the fact that plasma free and brain l‐tryptophan return to normal in the recovered animal.
Effects of prenatal exposure to amphetamine in the medial prefrontal cortex of the rat
Authors: Tavares M.A. , Silva M.C. , Silva‐Araújo A. , Xavier M.R. , Ali S.F.
Published: November 2004

This study was designed to investigate the effects of prenatal exposure to amphetamine in the organization of the medial prefrontal cortex of the rat, by an evaluation of growth, morphometric and neurochemical parameters. Pregnant Wistar rats were given 10 mg/kg body weight/day of D‐amphetamine sulfate, subcutaneously, from gestational days 8 to 22. Control groups of pregnant rats were injected with saline, pair‐fed or non‐manipulated; litters were culled to eight pups (four males and four females), weighed every other day until postnatal day 30 and every week until day 90. The Gompertz model was used to study body weight evolution and the estimated growth parameters were not significantly different in the experimental groups. At postnatal days 14 and 30, the volumes of the prefrontal cortex, the fraction of neuropile occupied by neurons and the number of neurons per unit surface area were determined. The number of neurons per unit volume of reference area was calculated using the stereological technique of the dissector. For neurochemical analysis, the medial prefrontal cortex was dissected to measure the concentration of dopamine, serotonin and their metabolites. The allometric relationship of forebrain/body growth pointed to a mechanism of sparing and compensatory growth in the amphetamine exposed group. The changes found in the number of neurons per unit volume at postnatal day 14 show a catch‐up at postnatal day 30. A decrease in serotonin levels was found in the amphetamine group compared with the pair‐fed control, which was reflected in the ratio of serotonin to its metabolite, 5‐hydroxyindolacetic acid. These changes, whether permanent or transitory, raise the possibility that some of the effects of prenatal exposure to amphetamine may be due to modifications in the neurotransmitter levels of serotonin.
Tryptophan restriction causes long‐term plastic changes in corticofrontal pyramidal neurons
Authors: González‐Burgos I. , Del Angel‐Meza A.R. , Barajas‐López G. , Feria‐Velasco A.
Published: November 2004

A Golgi study of third‐layer pyramidal neurons from the corticofrontal cortex of tryptophanrestricted rats was carried out. At 40 days of age, dendritic arborization from treated rats was less profuse than that seen in control rats, and enlargement of dendritic processes, as well as an increase of the number of dendritic spines, were observed in 60‐day‐old rats. These plastic responses could be mediated either by a decrease in serotonin, which acts on the serotoninergic receptors of pyramidal neurons, or through an indirect mechanism mediated by cortical interneurons, or by serotoninergic modulation of the activity of other cortical neurotransmitters such as acetylcholine. Also, it could represent compensatory mechanisms underlying behavioral performance in some paradigms related to several cognitive processes.
Seasonal growth pattern in the lichen Pseudocyphellaria berberina in north-western Patagonia
Authors: CALDIZ Mayra S.
Published: November 2004

Seasonal growth increments (%) were measured in the foliose epiphytic lichen Pseudocyphellaria berberina in north-western Patagonia. Growth was determined by measuring increase in weight (expressed as percentage of the original biomass) in transplanted thalli. Transplants were either hung freely from wooden frames or attached to tree trunks in a Nothofagus dombeyi forest and then weighed every three months between January 2001 and April 2003. The influence on growth increment of treatment, donor thallus, temperature, and absolute and relative humidity was analysed. Mean annual growth increment after two years, in both treatments was 12±1·07% (±SE). Growth increment was greatest in winter and lowest in summer; the mean winter growth increment was 6±0·50%, representing half of the annual growth, whereas most of the remaining growth occurred during both spring and autumn. Growth increments were similar for freely-hanging lichens and for the transplants attached to tree trunks. Individual trees had no consistent effect on growth while the donor thallus had a significant effect in the first season which then diminished, indicating acclimation in the transplants. Initial transplant weight had no influence on final cumulative growth, nor was there any consistent correlation between one season and another in the growth of transplants. Both transplantation methods proved to be useful for experiments on the growth of P. berberina.
A remarkable new freshwater Verrucaria from Europe
Authors: ORANGE Alan
Published: November 2004

Verrucaria madida is described as a new species with a green, subgelatinous thallus, and small ascospores; it is unique in the genus in having 4-spored asci. Three other small-spored freshwater species, V. aquatilis, V. rheitrophila and V. scabra, are compared. The type of pigment in the thallus cortex is a useful taxonomic character in the genus.
Verrucaria papillosa is a synonym of V. viridula
Authors: Orange Alan
Published: November 2004

Verrucaria papillosa Ach. (1803) is one of the earlier published names in the lichen family Verrucariaceae, and is still in use today; it is listed as an accepted species in recent checklists and floras including Clauzade & Roux (1985), Coppins (2002), Nimis (1993), Santesson (1993) and Santesson et al. (2004). However, examination of the holotype in April 2004 showed that it falls within the current concept of Verrucaria viridula (Schrad.) Ach.
New species in Tetramelas
Authors: NORDIN Anders
Published: November 2004

Three species are added to the recently reintroduced genus Tetramelas, T. chloroleucus comb. nov., T. confusus sp. nov. and T. granulosus comb. nov. Tetramelas confusus was first reported under the name of Buellia papillata but is more similar to T. insignis. Distinguishing characters are given in a Table. Tetramelas poeltii is reduced to synonymy with T. chloroleucus.
Genetic diversity in Xanthoria parietina (L.) Th. Fr. (lichen-forming ascomycete) from worldwide locations
Authors: HONEGGER Rosmarie , ZIPPLER Undine , SCHERRER Sandra , DYER Paul S.
Published: November 2004

Specimens of Xanthoria parietina were collected from worldwide locations and ascospore discharge used to establish axenic cultures of the mycobiont. DNA was extracted and RAPD-PCR fingerprinting of 59 isolates was successfully achieved, resulting in 58 unique fingerprints. 110 multilocus RAPD markers were generated and used to construct a dendrogram. Two main groups were distinguished (75% bootstrap support): the first comprising samples from the Iberian Peninsula, the Balearic and Canary Islands; the second comprising all other worldwide samples including isolates from throughout Europe and North America. Samples from Australia and New Zealand clustered with the second group except one additional, phenotypically distinct specimen, not belonging to X. parietina, which formed an outgroup. However, comparative DNA sequence analyses are required to verify this interpretation.
Thermoregulatory behaviour of gravid and non‐gravid female grass snakes (Natrix natrix) in a thermally limiting high‐latitude environment
Authors: Isaac Leigh Anne , Gregory Patrick T.
Published: November 2004

All else being equal, ectotherms should maintain body temperatures (Tbs) favourable for temperature‐sensitive biological functions, such as digestion and locomotion. Physical environments in the temperate zone are often thermally variable, however, thus making it difficult to maintain optimum Tbs. Radiotelemetry and a semi‐natural enclosure were used to monitor Tbs of grass snakes Natrix natrix at Canterbury, Kent, U.K. Operative temperatures (Tes) were measured using snake models (copper‐pipe models) placed in a variety of microhabitats to determine availability of thermoregulatory opportunities. A modification of Huey & Slatkin's (1976) regression model, piecewise regression, was used to evaluate thermoregulatory behaviour. Grass snakes could achieve high mean Tbs (> 30°C) most often during midday (08:00–20:00), but only for 55–61% of the study period. Overall, non‐gravid snakes maintained higher and less variable mean daytime Tbs than gravid snakes. From piecewise regression, it was determined that grass snakes initiated thermoregulation at a Te of 38.44 °C, corresponding to a Tb of 27.7 °C. Three main conclusions can be drawn from this study: (1) thermoregulatory opportunities for grass snakes were limited; (2) nonetheless, when conditions were sufficiently warm, there was clear evidence that grass snakes could thermoregulate; (3) contrary to expectation, gravid females actually maintained lower and more variable Tbs than non‐gravid females. The consequences of these thermoregulatory patterns for the fitness of snakes have yet to be determined.
Rapid disintegration of Alpine glaciers observed with satellite data
Authors: Paul Frank , Kääb Andreas , Maisch Max , Kellenberger Tobias , Haeberli Wilfried
Published: November 2004

Analyses of multispectral satellite data indicate accelerated glacier decline around the globe since the 1980s. By using digitized glacier outlines inferred from the 1973 inventory and Landsat Thematic Mapper (TM) satellite data from 1985 to 1999, we obtained area changes of about 930 Alpine glaciers. The 18% area reduction as observed for the period 1985 to 1999 (−1.3% a−1) corresponds to a seven times higher loss rate compared to the 1850–1973 decadal mean. Extrapolation of area change rates and cumulative mass balances to all Alpine glaciers yields a corresponding volume loss of about 25 km3 since 1973. Highly individual and non‐uniform changes in glacier geometry (disintegration) indicate a massive down‐wasting rather than a dynamic response to a changed climate. Our results imply stronger ongoing glacier retreat than assumed so far and a probable further enhancement of glacier disintegration by positive feedbacks.
A global lightning location algorithm based on the electromagnetic signature in the Schumann resonance band
Authors: Greenberg Eran , Price Colin
Published: November 2004

A new improved algorithm has been developed to geolocate intense lightning flashes around the globe. The method uses ELF (extremely low frequency) radiation propagated in the Earth‐ionosphere cavity to locate unusually intense lightning strokes. Two parameters are needed to locate the lightning discharge from a single station: bearing and source‐observer distance (SOD). The bearing was obtained using the Poynting vector (E × H), while the SOD was obtained on the basis of the modeling of the electric and magnetic ELF spectra and the comparison with experimental data. To check the accuracy of our algorithm, we used primarily infrared cloud top temperature images of deep convective storms from geostationary satellites (METEOSAT, GOES, and GMS). Analysis of ELF data from our field station of 147 events gave an average source‐observer distance error of 660 km (7.05%) and azimuth error of 1.9°. Of the 147 events, 72% had positive polarity, while the majority (59%) occurred over the oceans.
Version 2 data of the National Science Foundation's Ultraviolet Radiation Monitoring Network: South Pole
Authors: Bernhard G. , Booth C. R. , Ehramjian J. C.
Published: November 2004

Spectral ultraviolet (UV) and visible irradiance has been measured at the South Pole between 1991 and 2003 by a SUV‐100 spectroradiometer, which is part of the U.S. National Science Foundation's UV Monitoring Network. Here we present a new data edition, labeled “Version 2.” The new version was corrected for wavelength shift errors and deviations of the spectroradiometer from the ideal cosine response. A comprehensive uncertainty budget of the new data set was established. Below 400 nm the expanded standard uncertainty (coverage factor 2) varies between 4.6 and 7.2%, depending on wavelength and sky condition. The uncertainty of biologically relevant UV irradiances is approximately 6%. Compared to the previously published data set, Version 2 UV data are higher by 5–14%, depending on wavelength, solar zenith angle (SZA), and year of observation. By comparing Version 2 data with results of a radiative transfer model, the good consistency and homogeneity of the new data set were confirmed. The data set is used to establish a UV climatology for the South Pole, focusing on the effects of aerosols, clouds, and total column ozone. Clouds are predominantly optically thin; 71% of all clouds have an optical depth between 0 and 1. The average attenuation of UV irradiance at 345 nm by clouds is less than 5% and no attenuations greater than 23% were observed. Attenuation by homogeneous clouds is generally larger in the visible than in the UV. The wavelength dependence of cloud attenuation is quantitatively explained with the wavelength‐dependent radiance distribution on top of clouds and the incidence‐angle dependence of cloud transmittance. Largest radiation levels occur in late November and early December when low stratospheric ozone amounts coincide with relatively small SZAs. Owing to the large effect of the “ozone hole,” short‐ and long‐term variability of UV during the austral spring is very high. When the ozone hole disappears, DNA‐damaging irradiance can decrease by more than a factor of two within 2 days. Typical summer UV index values range between 2 and 3.5 and vary by ±30% (±1σ) between different years. Linear regression analyses did not indicate statistically significant UV trends owing to the large year‐to‐year variability and the fact that the network was established only after the first occurrence of the ozone hole. Current measurements therefore document variability on an elevated level.
Evidence that the spectral dependence of light absorption by aerosols is affected by organic carbon
Authors: Kirchstetter Thomas W. , Novakov T. , Hobbs Peter V.
Published: November 2004

The wavelength dependence of light absorption by aerosols collected on filters is investigated throughout the near‐ultraviolet to near‐infrared spectral region. Measurements were made using an optical transmission method. Aerosols produced by biomass combustion, including wood and savanna burning, and by motor vehicles, including diesel trucks, are included in the analysis. These aerosol types were distinguished by different wavelength (λ) dependences in light absorption. Light absorption by the motor vehicle aerosols exhibited relatively weak wavelength dependence; absorption varied approximately as λ−1, indicating that black carbon (BC) was the dominant absorbing aerosol component. By contrast, the biomass smoke aerosols had much stronger wavelength dependence, approximately λ−2. The stronger spectral dependence was the result of enhanced light absorption at wavelengths shorter than 600 nm and was largely reduced when much of the sample organic carbon (OC) was extracted by dissolution in acetone. This indicates that OC in addition to BC in the biomass smoke aerosols contributed significantly to measured light absorption in the ultraviolet and visible spectral regions and that OC in biomass burning aerosols may appreciably absorb solar radiation. Estimated absorption efficiencies and imaginary refractive indices are presented for the OC extracted from biomass burning samples and the BC in motor vehicle‐dominated aerosol samples. The uncertainty of these constants is discussed. Overall, results of this investigation show that low‐temperature, incomplete combustion processes, including biomass burning, can produce light‐absorbing aerosols that exhibit much stronger spectral dependence than high‐temperature combustion processes, such as diesel combustion.
Cardiovascular effects of sphingosine‐1‐phosphate and other sphingomyelin metabolites
Authors: Alewijnse Astrid E , Peters Stephan L M , Michel Martin C
Published: November 2004

Upon various stimuli, cells metabolize sphingomyelin from the cellular plasma membrane to form sphingosylphosphorylcholine (SPC) or ceramide. The latter can be further metabolized to sphingosine and then sphingosine‐1‐phosphate (S1P). Apart from local formation, S1P and SPC are major constituents of blood plasma.

All four sphingomyelin metabolites (SMM) can act upon intracellular targets, and at least S1P and probably also SPC can additionally act upon G‐protein‐coupled receptors. While the molecular identity of the SPC receptors remains unclear, several subtypes of S1P receptors have been cloned and their distribution in cardiovascular tissues is described.

In the heart SMM can alter intracellular Ca2+ release, particularly via the ryanodine receptor, and conductance of various ion channels in the plasma membrane, particularly IK(Ach). While the various SMM differ somewhat in their effects, the above alterations of ion homeostasis result in reduced cardiac function in most cases, and ceramide and/or sphingosine may be the mediators of the negative inotropic effects of tumour necrosis factor.

In the vasculature, SMM mainly act as acute vasoconstrictors in most vessels, but ceramide can be a vasodilator. SMM‐induced vasoconstriction involves mobilization of Ca2+ from intracellular stores, influx of extracellular Ca2+ via L‐type channels and activation of a rho‐kinase.

Extended exposure to SMM, particularly S1P, promotes several stages of the angiogenic process like endothelial cell activation, migration, proliferation, tube formation and vascular maturation.

We propose that SMM are an important class of endogenous modulators of cardiovascular function.

British Journal of Pharmacology (2004) 143, 666–684. doi:10.1038/sj.bjp.0705934
Contribution of the endothelin and renin–angiotensin systems to the vascular changes in rats chronically treated with ouabain
Authors: Xavier Fabiano E , Yogi Álvaro , Callera Gláucia E , Tostes Rita C , Alvarez Yolanda , Salaices Mercedes , Alonso María J , Rossoni Luciana V
Published: November 2004

Renin–angiotensin and endothelin systems are involved in the cardiovascular effects produced by treatment with ouabain. We recently demonstrated that the contractile response to phenylephrine is decreased in ouabain‐treated rats. The present study investigated whether endothelin‐1 (ET‐1) and angiotensin II (Ang II) contributes to the vascular changes observed in rats chronically treated with ouabain.

Wistar rats were treated with ouabain (8.0 μg day−1, s.c. pellets for 5 weeks) alone or in combination with an endothelin type A receptor (ETA) antagonist, BMS182874 (40 mg kg−1 day−1, per gavage) or an angiotensin type 1 (AT1) receptor antagonist, losartan (15 mg kg−1 day−1, p.o.).

Treatment with ouabain increased systolic blood pressure and treatment with either losartan or BMS182874 prevented the development of ouabain‐induced hypertension.

The sensitivity and maximal response for phenylephrine were reduced in aortic rings from ouabain‐treated rats. Removal of the endothelium or in vitro exposure to an inhibitor of nitric oxide synthase (NOS), N‐nitro‐L‐arginine methyl ester (L‐NAME, 100 μM) increased the responses to phenylephrine, an effect that was more pronounced in aortas from ouabain‐treated rats. Endothelial NOS protein (eNOS) expression was increased after ouabain treatment. Treatment with BMS182874, but not with losartan, prevented the effects of ouabain on the reactivity of phenylephrine and in eNOS protein expression.

Gene expression of pre–pro‐ET‐1 and ETA receptors was increased in aortic rings from ouabain‐treated rats. ETB receptor gene expression was not altered by ouabain treatment.

In conclusion, our results suggest that endothelin and angiotensin systems play an important role in the development of ouabain‐induced hypertension. However, ET‐1, by activation of ETA receptors, but not Ang II, contributes to changes in vascular reactivity to phenylephrine induced by chronic treatment with ouabain.

British Journal of Pharmacology (2004) 143, 794–802. doi:10.1038/sj.bjp.0705994
Fractional Brownian dynamics in proteins
Authors: Kneller G. R. , Hinsen K.
Published: November 2004

Correlation functions describing relaxation processes in proteins and other complex molecular systems are known to exhibit a nonexponential decay. The simulation study presented here shows that fractional Brownian dynamics is a good model for the internal dynamics of a lysozyme molecule in solution. We show that both the dynamic structure factor and the associated memory function fit well the corresponding analytical functions calculated from the model. The numerical analysis is based on autoregressive modeling of time series.
Reaction kinetics of the addition of atomic sulfur to nitric oxide
Authors: Goumri A. , Shao Diane D. , Marshall Paul
Published: November 2004

The reaction of S(3PJ) with NO (2Π) in an Ar bath gas has been studied by the laser photolysis-resonance fluorescence technique over 300–810 K at pressures from 60 to 800 mbar. The observed second-order rate constants are close to the low-pressure limit. Fitting of Troe’s formalism to experiment, with an estimated Fcent=0.78 exp(−T/7445) and k∞ given subsequently, yields k0=(6.2±0.6)×10−33 exp(+(940±40)/T) cm6 molecule−2 s−1. Error limits are ±25%. A theoretical analysis of this value suggests that the average energy transferred during collisions between Ar and the excited intermediate is 〈ΔE〉=−360−160+90 cm−1. Over 300–800 K, the high-pressure limit is predicted to be k∞=2.2×10−10 (T/300)0.24 cm3 molecule−1 s−1. Doublet and quartet adducts between S and NO were characterized via CBS-QB3 theory. The kinetic data can be rationalized with SNO (2A′) as the major product, and an ab initio estimate of ΔfH298 for SNO is 176±8 kJ mol−1.
Line shapes and satellites in high-resolution x-ray photoelectron spectra of large π-conjugated organic molecules
Authors: Schöll A. , Zou Y. , Jung M. , Schmidt Th. , Fink R. , Umbach E.
Published: November 2004

We present a high-resolution C1s and O1s x-ray photoemission (XPS) study for condensed films of π-conjugated organic molecules, namely, of the anhydrides 3,4,9,10-perylene-tetracarboxylic acid dianhydride, 1,4,5,8-naphthalene-tetracarboxylic acid dianhydride, 1,8-naphthalene dicarboxylic acid anhydride, and benzoperylene-(1,8)-dicarboxylic acid anhydride as well as the quinoic acenaphthenequinone. Although the functional groups are identical for the anhydrides, the molecules show very different photoemission fine structure thus providing a detailed fingerprint. A simultaneous peak fit analysis of the XPS spectra of all molecules allows to consistently determine the ionization potentials of all chemically different carbon and oxygen atoms. Additional structures in the C1s and O1s spectra are interpreted as shakeup satellites and assigned with the help of singles and doubles configuration interaction calculations. These satellites provide further information on multielectron excitations and must be taken into account for quantitative investigations.
A modified TIP3P water potential for simulation with Ewald summation
Authors: Price Daniel J. , Brooks Charles L.
Published: November 2004

The charges and Lennard-Jones parameters of the TIP3P water potential have been modified to improve its performance under the common condition for molecular dynamics simulations of using Ewald summation in lieu of relatively short nonbonded truncation schemes. These parameters were optimized under the condition that the hydrogen atoms do not have Lennard-Jones parameters, thus making the model independent of the combining rules used for the calculation of nonbonded, heteroatomic interaction energies, and limiting the number of Lennard-Jones calculations required. Under these conditions, this model provides accurate density (ρ=0.997 g/ml) and heat of vaporization (ΔHvap=10.53 kcal/mol) at 25 °C and 1 atm, but also provides improved structure in the second peak of the O–O radial distribution function and improved values for the dielectric constant (ε0=89) and the diffusion coefficient (D=4.0×10−5 cm2/s) relative to the original parametrization. Like the original parameterization, however, this model does not show a temperature density maximum. Several similar models are considered with the additional constraint of trying to match the performance of the optimized potentials for liquid simulation atom force field to that obtained when using the simulation conditions under which it was originally designed, but no model was entirely satisfactory in reproducing the relative difference in free energies of hydration between the model compounds, phenol and benzene. Finally, a model that incorporates a long-range correction for truncated Lennard-Jones interactions is presented, which provides a very accurate dielectric constant (ε0=76), however, the improvement in this estimate is on the same order as the uncertainty in the calculation.
Selection rules for probing biexcitons and electron spin transitions in isotropic quantum dot ensembles
Authors: Scholes Gregory D.
Published: November 2004

Three-dimensional rotational averages are evaluated for third-order nonlinear spectroscopic measurements of quantum dots. Photon echo, transient grating, and transient absorption are explicitly considered. It is shown that (a) biexciton formation can be suppressed relative to other contributions to nonlinear spectroscopies for isotropic nanocrystal ensembles by choice of polarizations for the excitation pulses; (b) circularly polarized excitation light can differentiate between exciton spin states in nonlinear optical experiments; and (c) electron spin state flip kinetics can be probed directly in an isotropic quantum dot system by using certain sequences of linear cross-polarized pulses.
Combinatorial entropy and phase diagram of partially ordered ice phases
Authors: MacDowell Luis G. , Sanz Eduardo , Vega Carlos , Abascal José Luis F.
Published: November 2004

A close analytical estimate for the combinatorial entropy of partially ordered ice phases is presented. The expression obtained is very general, as it can be used for any ice phase obeying the Bernal-Fowler rules. The only input required is a number of crystallographic parameters, and the experimentally observed proton site occupancies. For fully disordered phases such as hexagonal ice, it recovers the result deduced by Pauling, while for fully ordered ice it is found to vanish. Although the space groups determined for ice I, VI, and VII require random proton site occupancies, it is found that such random allocation of protons does not necessarily imply random orientational disorder. The theoretical estimate for the combinatorial entropy is employed together with free energy calculations in order to obtain the phase diagram of ice from 0 to 10 GPa. Overall qualitative agreement with experiment is found for the TIP4P model of water. An accurate estimate of the combinatorial entropy is found to play an important role in determining the stability of partially ordered ice phases, such as ice III and ice V.
Spatial distributions of angular momenta in quantum and quasiclassical stereodynamics
Authors: de Miranda Marcelo P. , Aoiz F. Javier , Sáez-Rábanos V. , Brouard Mark
Published: November 2004

We have recently reported a derivation of the relationship between the quantum and classical descriptions of angular momentum polarization [M. P. de Miranda and F. Javier Aoiz, Phys. Rev. Lett. 93, 083201 (2004)]. This paper presents a detailed account of the derivation outlined in that paper, and discusses the implications of the new results. These include (i) a new expression of the role of the uncertainty principle in the broadening of angular momentum distributions, (ii) the attribution of azimuthal fluctuations of angular momentum distributions to spatial quantum beats, (iii) the definition of a new Fourier transform of the density matrix, distinct from those suggested in the past, that provides an alternative view of how the quantum description of angular momentum polarization approaches the classical one in the correspondence principle limit, (iv) a prescription for the determination of a quasiclassical angular momentum distribution function that does not suffer from problems encountered with its purely classical counterpart, and (v) a description of how angular momentum distributions commonly visualized with recourse to the classical vector model can be depicted with exact and well-defined quantum mechanics.
The Major Target of the Endogenously Generated Reactive Oxygen Species in Response to Insulin Stimulation Is Phosphatase and Tensin Homolog and Not Phosphoinositide-3 Kinase (PI-3 Kinase) in the PI-3 Kinase/Akt Pathway
Authors: Seo Ji Hae , Ahn Younghee , Lee Seung-Rock , Yeo Chang Yeol , Hur Kyu Chung
Published: November 2004

Phosphoinositide-3 kinase (PI-3 kinase) and its downstream signaling molecules PDK-1 and Akt were analyzed in SK-N-SH and SK-N-BE(2) human neuroblastoma cell lines. When cells were stimulated with insulin, PI-3 kinase was activated in both cell lines, whereas the translocation of PDK-1 to the membrane fraction and phosphorylated Akt were observed only in SK-N-SH cells. Analyses of the insulin-mediated reactive oxygen species (ROS) generation and Phosphatase and Tensin homolog (PTEN) oxidation indicate that PTEN oxidation occurred in SK-N-SH cells, which can produce ROS, but not in SK-N-BE(2) cells, which cannot increase ROS in response to insulin stimulation. When SK-N-SH cells were pretreated with the NADPH oxidase inhibitor diphenyleneiodonium chloride before insulin stimulation, insulin-mediated translocation of PDK-1 to the membrane fraction and phosphorylation of Akt were remarkably reduced, whereas PI-3 kinase activity was not changed significantly. These results indicate that not only PI-3 kinase activation but also inhibition of PTEN by ROS is needed to increase cellular level of phosphatidylinositol 3,4,5-trisphosphate for recruiting downstream signaling molecules such as PDK-1 and Akt in insulin-mediated signaling. Moreover, the ROS generated by insulin stimulation mainly contributes to the inactivation of PTEN and not to the activation of PI-3 kinase in the PI-3 kinase/Akt pathway.