bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of phenyl radical reactions with propane, n‐butane, n‐hexane, and n‐octane: Reactivity of C6H5 toward the secondary CH bond of alkanes
Authors: Park J. , Wang Liming , Lin M. C.
Published: November 2003

The kinetics of C6H5 reactions with n‐CnH2n+2 (n = 3, 4, 6, 8) have been studied by the pulsed laser photolysis/mass spectrometric method using C6H5COCH3 as the phenyl precursor at temperatures between 494 and 1051 K. The rate constants were determined by kinetic modeling of the absolute yields of C6H6 at each temperature. Another major product C6H5CH3 formed by the recombination of C6H5 and CH3 could also be quantitatively modeled using the known rate constant for the reaction. A weighted least‐squares analysis of the four sets of data gave k (C3H8) = (1.96 ± 0.15) × 1011 exp[−(1938 ± 56)/T], and k (n‐C4H10) = (2.65 ± 0.23) × 1011 exp[−(1950 ± 55)/T] k (n‐C6H14) = (4.56 ± 0.21) × 1011 exp[−(1735 ± 55)/T], and k (n−C8H18) = (4.31 ± 0.39) × 1011 exp[−(1415 ± 65)T] cm3 mol−1 s−1 for the temperature range studied. For the butane and hexane reactions, we have also applied the CRDS technique to extend our temperature range down to 297 K; the results obtained by the decay of C6H5 with CRDS agree fully with those determined by absolute product yield measurements with PLP/MS. Weighted least‐squares analyses of these two sets of data gave rise to k (n−C4H10) = (2.70 ± 0.15) × 1011 exp[−(1880 ± 127)/T] and k (n−C6H14) = (4.81 ± 0.30) × 1011 exp[−(1780 ± 133)/T] cm3 mol−1 s−1 for the temperature range 297‐‐1046 K. From the absolute rate constants for the two larger molecular reactions (C6H5 + n‐C6H14 and n‐C8H18), we derived the rate constant for H‐abstraction from a secondary CH bond, ks−CH = (4.19 ± 0.24) × 1010 exp[−(1770 ± 48)/T] cm3 mol−1 s−1. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 36: 49–56, 2004
NANOVIBR: Parallel codes for semiempirical quantum chemical and harmonic vibration large‐scale calculations
Authors: Berzigiyarov Parvaz K. , Zayets Valentine A. , Ginzburg Ilya Y. , Razumov Vladimir F. , Sheka Elena F.
Published: November 2003

Package NANOVIBR is a further development of the NANOPACK software (Int J Quantum Chem 2002, 88, 449) and is dedicated to both semiempirical quantum chemical (QCh) calculations of nano‐sized systems and harmonic vibrational problem solution for several hundred atom systems, with a particular stress on the latter. Sequential codes CLUSTER‐Z1 and CLUSTER‐Z2 form the ground of the package and provide extended QCh calculations of structural and electronic characteristics in the sp‐ and spd‐basis, as well as of force fields, harmonic vibrational frequencies, infrared, and Raman spectra intensities. The combination of fine‐grained (self‐consistent field calculation) and coarse‐grained (Hessian and spectra intensities) regimes of the parallel codes implementation results in a considerable enhancement of the calculation speed‐up. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Fluorination of carbon nanotubes: Quantum chemical investigation within MNDO approximation
Authors: Lebedev N. G. , Zaporotskova I. V. , Chernozatonskii L. A.
Published: November 2003

Computations of (6, 0), (8, 0), (6, 6), (7, 7), and (8, 8) single‐wall carbon nanotubes fluorination processes have been carried out within the framework of molecular cluster model and semiempirical quantum chemical MNDO scheme. The adsorption energy of fluorine atom as a function of distance from the surface carbon has been constructed. Chemical stable and van der Waals metastable stations of an F atom on nanotube surfaces have been found. The adsorption process of two fluorine atoms on adjacent surface carbons has been studied. It has been found that the second fluorine atom is adsorbing without van der Waals metastable station. The probability of the processes has been estimated in quasiclassic approaching. The greatest possible concentration ratio F/C of almost all investigated nanotubes have been obtained equal to 1 besides (8, 8) nanotube, for which the ratio is 0.75. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Does business planning facilitate the development of new ventures?
Authors: Delmar Frédéric , Shane Scott
Published: November 2003

Many prior researchers have criticized business planning, arguing that it interferes with the efforts of firm founders to undertake more valuable actions to develop their fledgling enterprises. In this paper, we challenge this negative view of business planning, arguing that business planning is an important precursor to action in new ventures. By helping firm founders to make decisions, to balance resource supply and demand, and to turn abstract goals into concrete operational steps, business planning reduces the likelihood of venture disbanding and accelerates product development and venture organizing activity. Empirically, we examine 223 new ventures initiated in the first 9 months of 1998 by a random sample of Swedish firm founders and provide support for our hypotheses. Copyright © 2003 John Wiley & Sons, Ltd.
Organizational slack and firm performance during economic transitions: two studies from an emerging economy
Authors: Tan Justin , Peng Mike W.
Published: November 2003

An Erratum has been published for this article in Strategic Management Journal 25(3) 2004, 307.

How does organizational slack affect firm performance? Organization theory posits that slack, despite its costs, has a positive impact on firm performance. In contrast, agency theory suggests that slack breeds inefficiency and inhibits performance. The empirical evidence, largely from developed economies, has been inconclusive. Moreover, little effort has been made to empirically test whether such an impact (positive or negative) is linear or curvilinear. This article joins the debate by extending empirical work to the largely unexplored context of economic transitions. Specifically, two studies, based on survey and archival data (N = 57 and 1532 firms, respectively), are undertaken in China's emerging economy. Our results suggest (1) that organization theory generates stronger predictions when dealing with unabsorbed slack, and (2) that agency theory yields stronger validity when focusing on absorbed slack. Furthermore, we also find that the impact of slack on performance is curvilinear, which resembles inverse U‐shaped curves. Overall, our findings call for a contingency perspective to specify the nature of slack when discussing its impact on firm performance. Copyright © 2003 John Wiley & Sons, Ltd.
Alliance form: a test of the contractual and competence perspectives
Authors: Colombo Massimo G.
Published: November 2003

This paper analyzes factors that influence firms' choice of the organizational form of strategic alliances. I consider arguments suggested by both the contractual and the competence perspectives. In order to distinguish empirically between them, I devote special attention to the role played by the similarity of partner firms' technological specialization. In the empirical section I consider a sample composed of 271 equity joint ventures, non‐equity bilateral and unilateral agreements established between each other in the period 1983–86 by 67 North American, European, and Japanese enterprises from the world's largest firms in information technology industries. I examine the effects on the choice of alliance form of a measure of firms' technological proximity based on patents count, while controlling for other variables that are usually considered in the empirical literature. The estimates of binomial and multinomial logit models support the competence‐based argument that in technological alliances divergence in partners' technological specialization results in a higher propensity to use equity forms. Overall, the findings suggest that both the contractual and competence perspectives provide valuable complementary insights into the determinants of alliance form. Copyright © 2003 John Wiley & Sons, Ltd.
Geographic scope and multinational enterprise performance
Authors: Goerzen Anthony , Beamish Paul W.
Published: November 2003

Through an internalization theory lens, an argument is developed to suggest that the traditional concept of geographic scope should be split into two related, but more precise, elements of international asset dispersion and country environment diversity. Subsequently, these new concepts are tested using a structural equation modeling approach on a sample of 580 large multinational enterprises (MNEs). We find that the relationship between economic performance and international asset dispersion is positive, but that country environment diversity is negatively associated with performance, with a positive interaction between them. This study adds to our theoretical understanding of MNEs, and also provides a bridge between the mixed findings of prior research on multinationality by disentangling the unique effects of the latent subcomponents of geographic scope on firm performance. Copyright © 2003 John Wiley & Sons, Ltd.
Defining and redirecting a school‐to‐prison pipeline
Authors: Wald Johanna , Losen Daniel J.
Published: November 2003

The school‐to‐prison pipeline needs to be better defined and redirected toward greater opportunities for all youth.
Predictors of suspension and negative school outcomes: A longitudinal investigation
Authors: Raffaele Mendez Linda M.
Published: November 2003

Research suggests that suspension is not an effective deterrent and that more should be done to meet the needs of those who are continually suspended.
Identification of amino acid residues of Ras protein that are essential for signal‐transducing activity but not for enhancement of GTPase activity by GAP
Authors: Fujita-Yoshigaki Junko , Shirouzu Mikako , Koide Hiroshi , Nishimura Susumu , Yokoyama Shigeyuki
Published: November 2003

To determine the amino acid residues required for the signal‐transducing activity of the human c‐Ha‐Ras protein, we introduced point mutations at residues 45–54 near the ‘effector region’ (residues 32–40). We transfected PC12 cells with these mutant genes and also micro‐injected the mutant proteins bound with an unhydrolyzable GTP analog, into PC12 cells. Both procedures showed that Val45 → Glu and Gly48 → Cys mutations impaired the ability of the Ras protein to induce morphological change of PC12 cells. These mutations did not affect the guanine nucleotide‐binding activity or GTPase activity in the absence or presence of bovine GTPase‐activating protein (GAP). Therefore, the Val45 and Gly48 residues should be included by definition in the effector region responsible for the signal transduction, while only a subset of the effector‐region residues is required for enhancement of the GTPase activity by GAP.
A Lys27‐to‐Glu27 mutation in the human insulin‐like growth factor‐1 prevents disulfide linked dimerization and allows secretion of BiP when expressed in yeast
Authors: Chaudhuri Bhabatosh , Helliwell Stephen B. , Priestle John P.
Published: November 2003

Recombinant human insulin‐like growth factor‐1 (IGF1) secreted from yeast contains only 10–15% of the active monomer. A majority of the IGF1‐like molecules are disulfide bonded dimers. These dimers are not formed in an IGF1 mutant where Lys27 has been replaced by glutamic acid. However, increased levels of secreted BiP (the yeast KAR2 gene product) are seen in cells expressing the mutant. These results imply that by preventing ionic interactions between two IGF1 molecules, intermolecularm disulfide bonds do not form in yeast, and that in the mutant there is a structural change which induces BiP, allowing its secretion.
Binding of truncated peptides to the MHC molecule IAd
Authors: Dornmair Klaus , Clark Brian R. , McConnell Harden M.
Published: November 2003

A peptide comprising amino acids 323–339 of chicken ovalbumin is known to bind to two heterodimeric conformations of the MHC molecule IAd, and to each of its separate α‐ and β‐chains. We report that minor C‐ and N‐terminal truncations of the parent peptide do not alter the binding pattern. A decrease in binding activity was observed upon deletion of the histidine residues of the already truncated peptides. Peptides as short as 4 amino acids associate weakly with all four proteins.
Ganglioside‐dependent cell attachment and endocytosis of murine polyomavirus‐like particles
Authors: Smith Alicia E , Lilie Hauke , Helenius Ari
Published: November 2003

For murine polyomavirus (Py), previous studies suggest the cellular target is a terminal α2,3‐linked sialic acid. Here, we investigate the binding and uptake of mouse polyomavirus‐like particles (PyVLP) derived from bacterially expressed VP1. We find that in fibroblast 3T6 cells, binding of PyVLP was substantially reduced by sialidase treatment, but only moderately affected by protease treatment, suggesting glycolipids such as the sialic acid‐containing gangliosides mediate cell attachment. We further tested the entry requirement of PyVLP using the ganglioside‐deficient GM95 murine cell line, and find PyVLP binding and entry were reduced in these cells. Finally, we find that addition of gangliosides GM1, GD1a, and GT1b to GM95 cells restored cellular PyVLP binding and uptake. Taken together, results indicate that gangliosides function in PyVLP cell attachment and endocytosis.
Regulation of flotillin‐1 in the establishment of NIH‐3T3 cell–cell interactions1
Authors: López-Casas Pedro P. , del Mazo Jesús
Published: November 2003

Flotillin‐1 is a lipid raft‐associated protein involved in neuronal regeneration, insulin signaling in adipocytes, and phagosome maturation in macrophages. We detected abundant flotillin‐1 mRNA expression in confluent cultures of mouse NIH‐3T3 fibroblasts. These cells were used as a model to assess the regulation of flotillin‐1 mRNA and protein expression by cell–cell interactions. The disruption of cell–cell interactions triggered the downregulation of the flotillin‐1 gene. However, the establishment of new cell interactions, and finally confluence, increased both the flotillin‐1 transcript and its protein. Despite flotillin‐1 having been described as an integral protein of the cell membrane, it is also very conspicuous in the hydrophilic fraction (the non‐membrane fraction) of confluent cell extracts. The promoter region of the flotillin‐1 gene was isolated and analyzed by transfection experiments, and the regulatory domains containing motifs for binding transcription factors involved in cell differentiation were identified.
Chemical and Biological Parameters as Tools to Evaluate and Improve Heavy Metal Phytoremediation
Authors: Kamnev Alexander A. , van der Lelie Daniël
Published: November 2003

In this review, chemical and biological parameters are discussed thatstrongly influence the speciation of heavy metals, their availability tobiological systems and, consequently, the possibilities to usebioremediation as a cleanup tool for heavy metal polluted sites. In orderto assess heavy metal availability, a need exists for rapid, cost-effectivesystems that reliably predict this parameter and, based on this, thefeasibility of using biological remediation techniques for site managementand restoration. Special attention is paid to phytoremediation as anemerging technology for stabilization and remediation of heavy metalpollution. In order to improve phytoremediation of heavy metal pollutedsites, several important points relevant to the process have to beelucidated. These include the speciation and bioavailability of the heavymetals in the soil determined by many chemical and biological parameters, the role of plant-associated soil microorganisms and fungi inphytoremediation, and the plants. Several options are described how plant-associated soil microorganisms canbe used to improve heavy metal phytoremediation.
Bioenergetics of Human Peripheral Blood Mononuclear Cell Metabolism in Quiescent, Activated, and Glucocorticoid-Treated States
Authors: Schmid Dirk , Burmester Gerd-Rüdiger , Tripmacher Robert , Kuhnke Antje , Buttgereit Frank
Published: November 2003

The first quantitative findings on the energy metabolism of human immunecells are presented. In quiescent peripheral blood mononuclear cells(PBMC) protein biosynthesis and Na+,K+-ATPase activity eachaccounted for 8% of cellular oxygen consumption. Stimulation with 25, 50, and 75 μg Con A/ml (1.25, 2.5 or 3.75 μg/106 cells) increased totaloxygen consumption within seconds by 8, 36, and 53%, respectively. Afteraddition of 75 μg Con A/ml, the proportion of cellular oxygenconsumption due to protein biosynthesis, Na+,K+-ATPase activity, and Ca2+-ATPase activity was 15% each and that due to DNA/RNAsynthesis was 8%. On the basis of these findings the immediate effectsof five different glucocorticoids on cellular energy metabolism wereinvestigated. The various glucocorticoids exerted basically the sameinhibitory effects on Con A-stimulated cellular respiration and individualATP-consuming processes, but differed significantly in potency. Similar toprevious studies on rat thymocytes, the relative potencies of theglucocorticoids were found to be: prednylidene (1.7)<dexamethasone(1.5)<methylprednisolone (1.0)<prednisolone (0.3)0.2). Given their rapidity of onset, these effects must benongenomically mediated. The differences between the relative potencies ofthe various glucocorticoids for these effects and those for the classicalgenomic effects have important clinical implications, in particular forhigh-dose systemic and local glucocorticoid therapy.
Endogenous Lectins as Cell Surface Transducers
Authors: Hébert Eric
Published: November 2003

Interactions between cells or between cell and substratum involve specificreceptors and their ligands. Among the various cell surface receptorsidentified during the last decades, the carbohydrate-binding proteins, e.g., lectins are of peculiar interest because glycolipids, glycoproteinsand proteoglycans have been shown to interact with lectins on the surfaceof animal cells. Animal lectins are recognized as molecules playingimportant roles in a variety of biological processes through binding toglycoconjugates and lectin-like receptors such as selectins, sialoadhesins(CD22, CD33), natural killer receptors (NKR-P1, CD69 and CD94/NKG2), hyaluronate receptors (CD44, RHAMM, ICAM-1), B-cell associated antigen(CD23, CD72), γ2 leukocyte integrin (CD11b/CD18) or the well-knownreceptors for mannose, mannose-6-phosphate or asialoglycoprotein havebeen suggested to be able to mediate the transfer of information fromthe outside to the inside of the cell. This review focuses on the mostrecent advances in our understanding of the molecular basis of “outside-in” signaling mediated by lectins. Lectin-likereceptors are involved in signal transduction in a great variety of ways;at the molecular level, they mimic in most of the cases the function ofgrowth factor receptor either coupled to tyrosine kinase activity or toheterotrimeric G protein. They lead to a multiplicity of cellular eventsfollowing their activation depending on factors such as cellular type, species and/or tissue. Nevertheless the potential of surface lectins astransducers is emphasized by the observation that in a few cases lectin-likereceptors induce either novel signal transduction mechanism or newintracellular events with regards to what it has been observed as aconsequence of growth factor receptor activation. This observation bringsthe idea that lectins may offer, as cell surface transducers, an alternativeor additional signaling potential to cell.
Possible Protective Effect of Kolaviron on CCl4-Induced Erythrocyte Damage in Rats
Authors: Adaramoye Oluwatosin A. , Akinloye Oluyemi
Published: November 2003

The possible protective effect of kolaviron on rat erythrocytes followingsimultaneous administration of kolaviron (100 mg/kg of body weight/day) withcarbon tetrachloride CCl4 (1.195 g/kg of body weight/day) by separateintraperitoneal injections was investigated.

Kolaviron, a biflavonoid fraction of the defatted alcoholic extract of Garcinia kola seed, inhibits the accumulation of lipid peroxidationproducts in erythrocytes. A significant reduction (p>0.05) by about34% of lipid peroxidation products was observed in erythrocytes of ratstreated simultaneously with CCl4 and kolaviron when compared to CCl4-treatedrats. Similarly, the significant increase (p >0.05) in membranecholesterol observed in CCl4-treated rats was significantly decreased(p>0.05) in rats treated simultaneously with CCl4 andkolaviron. Therefore, there was no significant difference (p >0.05) incholesterol–phospholipid ratio (C/P) of rats treated simultaneouslywith CCl4 and kolaviron, and the controls. Thus, kolaviron normalizes the CCl4-induced change in erythrocyte membrane composition.

In addition, kolaviron antagonizes the effect of CCl4 on the activity ofthe membrane bound enzyme, Ca2+-ATPase. These results suggest thatkolaviron protects erythrocyte membranes from free radical attack, on bothlipids and proteins.
Tyrosine hydroxylase deficiency unresponsive to L‐dopa treatment with unusual clinical and biochemical presentation
Authors: De Lonlay P. , Nassogne M. C. , van Gennip A. H. , van Cruchten A. C. , Billette de Villemeur T. , Cretz M. , Stoll C. , Launay J. M. , Steenberger‐Spante G. C. V. , van den Heuvel L. P. W. , Wevers R. A. , Saudubray J. M. , Abeling N. G. G. M.
Published: November 2003

Tyrosine hydroxylase (TH) deficiency is generally considered as a cause of the autosomal recessive form of dopa‐responsive dystonia, also known as Segawa disease. Clinical hallmarks comprise parkinsonian and other extrapyramidal symptoms. Biochemically the defect leads to the defective synthesis of catecholamines, in particular dopamine. The diagnosis relies on a characteristic pattern of biogenic amine metabolites exclusively in the CSF and can be confirmed by establishing a mutation in the TH gene. Here we present a patient meeting all diagnostic criteria, including a new homozygous mutation (926T>C) with confirmed parental heterozygosity, extrapyramidal symptoms, but atypical other symptoms with periodic neurological episodes observed every 4 days and unresponsive to dopa treatment. The CSF biochemical abnormalities were severe. Uncharacteristically, a strongly abnormal urinary catecholamine metabolite pattern was also consistently observed. The atypical presentation of this patient shows that the clinical and metabolic phenotype of TH deficiency is more variable than formerly thought, and that the condition should no longer be considered as a treatable disorder per se.
Theoretisch-methodische Desiderata der medienpsychologischen Forschung über die aggressionsfördernde Wirkung gewalthaltiger Computer- und Videospiele
Authors: Klimmt Christoph , Trepte Sabine
Published: November 2003

Zusammenfassung. Obwohl die Gewalt in Computer- und Videospielen seit geraumer Zeit öffentlich debattiert wird, liegen bislang nur ungenügende theoretische Ansätze und empirische Studien zur medienpsychologischen Klärung möglicher aggressionsförderlicher Auswirkungen vor. Der Beitrag skizziert die zentralen Probleme der bisherigen Forschung in diesem Bereich und entwirft zugleich Strategien, diese Suboptimalitäten in Zukunft zu überwinden. Auf theoretisch-konzeptueller Ebene wird die Frage der (Effekt-)Modellierung des subjektiven Erlebens von Spielgewalt durch die Nutzer/innen sowie der Rolle von ‘Medienkompetenz‘ als Moderatorvariable diskutiert. Auf methodischer Ebene werden die Besonderheiten des Forschungsgegenstands bei Experimentalstudien hinterfragt und die Erklärungskraft von Längsschnittstudien geprüft.
Balanced sections and the propagation of décollement: A Jura perspective
Authors: Laubscher Hans
Published: November 2003

The propagation of thrusting is an important problem in tectonics that is usually approached by forward (kinematical) modeling of balanced sections. Although modeling techniques are similar in most foreland fold‐thrust belts, it turns out that in the Jura, there are modeling problems that require modifications of widely used techniques. In particular, attention is called to the role of model constraints that complement the set of observational constraints in order to fully define the model. In the eastern Jura, such model constraints may be inferred from the regional geology, which shows a peculiar noncoaxial relation between thrusts and subsequent folds. This relation implies changes in the direction of translation and the mode of deformation in the course of the propagation of décollement. These changes are conjectured to be the result of a change in partial decoupling between the thin‐skinned fold‐thrust system (nappe) and the obliquely subducted foreland. As a particularly instructive case in point, a cross section through the Weissenstein range is discussed. A two‐step forward (kinematical) model is proposed that uses both local observational constraints as well as model constraints inferred from regional data. As a first step, a fault bend fold is generated in the hanging wall of a thrust of 1500 m shortening. As a second step, this structure is transferred by flexural slip into the actual fold observed at the surface. This requires an additional 1600 m of shortening and leads to folding of the original thrust. Thereafter, the footwall is deformed so as to respect the constraint that this deformation must fit into the space defined by the folded thrust as the upper boundary and the décollement surface as the lower boundary, and that, in addition, should be confined to the area immediately below the fold. In modeling the footwall deformation a mix of balancing methods is used: fault propagation folds for the competent intervals of the stratigraphic column and area balancing for the incompetent ones. Further propagation of décollement into the foreland is made possible by the folding process, which is dominated by a sort of kinking and which is the main contribution to structural elevation and hence to producing a sort of critical taper of the moving thin‐skinned wedge.
Seismicity rate before eruptions on Piton de la Fournaise volcano: Implications for eruption dynamics
Authors: Collombet Marielle , Grasso Jean‐Robert , Ferrazzini Valérie
Published: November 2003

Individual eruptions are difficult to foresee using daily seismicity at Piton de la Fournaise (PdlF) volcano, except within a few hours from the eruption time. However, when using a superposed epoch analysis for all of the 15 eruptions in the 1988–2001 period, we find that the seismicity rate increases 2 weeks before the eruption time as (t) ∼ (te − t)−a, te being the eruption time. Such an increase mimics the pattern of stacked foreshock sequences, i.e., a power law increase in seismicity rate before earthquakes that is proposed to emerge from aftershocks properties [Helmstetter et al. 2003]. It argues for the bursts of seismicity rate before eruptions to both result from the volcano dynamics (volume or pressure increase induced by magma) and from the cascades of earthquake interactions. This latter process produces stochastic fluctuations in the seismicity rate that perturb any single pre‐eruption time series. The PdlF seismicity highlights a brittle pre‐eruption damage process which starts at least 2 weeks prior to eruption time. Because this increase is only measured upon averaging, it suggests that during the brittle damage phase the direct effect of volcano dynamics on the seismicity rate remains on the same order of magnitude as the seismicity rate triggered by volcano earthquake interactions.
The natural thermostat of nitric oxide emission at 5.3 μm in the thermosphere observed during the solar storms of April 2002
Authors: Mlynczak Marty , Martin‐Torres F. Javier , Russell James , Beaumont Ken , Jacobson Steven , Kozyra Janet , Lopez‐Puertas Manuel , Funke Bernd , Mertens Christopher , Gordley Larry , Picard Richard , Winick Jeremy , Wintersteiner Peter , Paxton Larry
Published: November 2003

The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) experiment on the Thermosphere‐Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite observed the infrared radiative response of the thermosphere to the solar storm events of April 2002. Large radiance enhancements were observed at 5.3 μm, which are due to emission from the vibration‐rotation bands of nitric oxide (NO). The emission by NO is indicative of the conversion of solar energy to infrared radiation within the atmosphere and represents a “natural thermostat” by which heat and energy are efficiently lost from the thermosphere to space and to the lower atmosphere. We describe the SABER observations at 5.3 μm and their interpretation in terms of energy loss. The infrared enhancements remain only for a few days, indicating that such perturbations to the thermospheric state, while dramatic, are short‐lived.
Jovian dust streams: A monitor of Io's volcanic plume activity
Authors: Krüger H. , Geissler P. , Horányi M. , Graps A. L. , Kempf S. , Srama R. , Moragas‐Klostermeyer G. , Moissl R. , Johnson T. V. , Grün E.
Published: November 2003

Streams of high speed dust particles originate from Jupiter's moon Io. After release from Io, the particles collect electric charges in the Io plasma torus, gain energy from the co‐rotating electric field of Jupiter's magnetosphere, and leave the Jovian system into interplanetary space with escape speeds over 200 km s−1. The Galileo spacecraft has continuously monitored the dust streams during 34 revolutions about Jupiter between 1996 and 2002. The observed dust fluxes exhibit large orbit‐to‐orbit variability due to systematic and stochastic changes. After removal of the systematic variations, the total dust emission rate of Io has been calculated. It varies between 10−3 and 10 kg s−1, and is typically in the range of 0.1 to 1 kg s−1. We compare the dust emission rate with other markers of volcanic activity on Io like large‐area surface changes caused by volcanic deposits and sightings of volcanic plumes.
Measuring terrestrial fluxes of methyl chloride and methyl bromide using a stable isotope tracer technique
Authors: Rhew Robert C. , Aydin Murat , Saltzman Eric S.
Published: November 2003

Atmospheric methyl chloride (CH3Cl) and methyl bromide (CH3Br), compounds involved in the destruction of stratospheric ozone, are simultaneously produced and consumed by the terrestrial biosphere. Here we present a stable isotope incubation technique using 13CH3Cl and 13CH3Br as tracers to simultaneously determine production and consumption fluxes in boreal forest soils from Alaska, USA. Measured uptake rates are consistent with previously reported boreal soil results for CH3Br and show a CH3Cl:CH3Br molar consumption ratio of 40:1. Boreal forest soils appear to produce small amounts of these methyl halides as well, but at rates that are negligible in their global budgets. This isotope tracer technique can be applied to laboratory studies of plants and other soils and to field measurements where disturbances to the system can be minimized.
Quantum yield for N(4S) production in the ultraviolet photolysis of N2O
Authors: Nakayama Tomoki , Takahashi Kenshi , Matsumi Yutaka , Taniguchi Nori , Hayashida Sachiko
Published: November 2003

Direct detection of N(4S) atom formation in the 193 nm photolysis of N2O by a technique of vacuum ultraviolet (vuv) laser‐induced fluorescence spectroscopy has been reported. Tunable vuv laser radiation around 120.071 nm that is resonant to the one‐photon N(2p23s 4P1/2 − 2p3 4S3/2) transition has been generated by two‐photon resonant four‐wave sum frequency mixing in Hg vapor. The quantum yield value for N(4S) formation in the N2O photolysis at 193 nm has been determined to be 2.1 (±0.9) × 10−3. The N(4S) detection technique, which is developed in this study, is very sensitive, and the minimum detection limit is estimated to be 2 × 109 atoms cm−3. Impact of the photolytic N(4S) and NO(X2Π) production from N2O photolysis on stratospheric chemistry has been explored using a one‐dimensional photochemical model, while the fragmentation was not considered in former model calculations. When the N(4S) + NO dissociation channel is considered in the photochemical model, an enhancement of the NOx production rate (up to 3%) is observed, which is followed by a decrease of the steady state O3 concentration throughout the stratosphere.
Evidence from sulfate mass independent oxygen isotopic compositions of dramatic changes in atmospheric oxidation following massive volcanic eruptions
Authors: Savarino Joël , Bekki Slimane , Cole‐Dai Jihong , Thiemens Mark H.
Published: November 2003

Oxygen isotopic ratio measurements (δ17O and δ18O) of background and volcanic sulfate preserved in South Pole snow and ice were used to investigate the impact on the oxidation state of the atmosphere by explosive volcanic eruptions. By comparing different paleovolcanic events, we observe a difference in the SO2 oxidation pathway between moderate (tens of teragrams (Tg) of SO2) and massive (hundreds of Tg) eruptions. Both isotopic data and numerical simulations suggest the shutdown of stratospheric OH chemistry and the opening of unaccounted oxidation channels for SO2, such as the reaction with O(3P) atoms when hundreds of Tg of SO2 are injected into the stratosphere. It is very likely that oxidation rates and pathways and concentrations of most traces gases are also dramatically affected, with potentially important implications for climate forcing.
Rift‐phase extensional fabrics of the back‐arc Drummond Basin, eastern Australia
Authors: Davis Brett K. , Henderson Robert A.
Published: November 2003

The base of the Late Devonian–Early Carboniferous Drummond Basin, a major backarc extensional feature in eastern Australia which formed in response to detachment faulting, is extensively exposed in central Queensland. Here a crystalline basin floor is overlain by the Silver Hills Volcanics, a synrift sequence of predominantly silicic ash flow tuffs and lavas ranging to over 2 km in thickness. Detailed mapping of faults and stratigraphic logging of thickness changes within the Silver Hills Volcanics have allowed the rift‐phase structural architecture that accompanied initial subsidence near the basin margin to be resolved. A complex mosaic of block faults with throws of up to 1 km is indicated. Locally developed mosaics may conform to, or depart from, the configuration predicted by the detachment faulting model. Structural fabric of the basement was a critical determinant of the extensional geometry. Distributed shear along pre‐existing penetrative planar fabrics is considered to have accommodated hangingwall extension at lower strain rates whereas the propagation of tension fractures and the development of block faults by failure on pre‐existing, brittle, basement dislocations facilitated extension at higher strain rates. The detachment fault inferred to lie beneath the extended hangingwall carapace has not been mapped at the surface and is thought to dissipate into a broad zone of distributed shear within basement to the east of the basin. Volcanism coincided with the initiation of extensional movements at which time deep crustal repositories for evolved magma were tapped by extensional fractures. The main extensional faults cutting the basinal succession were not used as conduits for magmatic products which were sourced from the basin margin and from extended hinterland to the east.
Late Quaternary sedimentation on the Leidy Creek fan, Nevada–California: geomorphic responses to climate change
Authors: Reheis Marith C. , Slate Janet L. , Throckmorton Constance K. , McGeehin John P. , Sarna‐Wojcicki Andrei M. , Dengler Lori
Published: November 2003

Well‐dated surface and subsurface deposits in semiarid Fish Lake Valley, Nevada and California, demonstrate that alluvial‐fan deposition is strongly associated with the warm dry climate of the last two interglacial intervals, and that fans were stable and (or) incised during the last glaciation. Fan deposition was probably triggered by a change from relatively moist to arid conditions causing a decrease in vegetation cover and increases in flash floods and sediment yield. We think that this scenario applies to most of the other valleys in the southern Basin and Range.

Radiocarbon, tephra, and a few thermoluminescence and cosmogenic ages from outcrops throughout Fish Lake Valley and from cores on the Leidy Creek fan yield ages of >100–50 ka and 11–0 ka for the last two periods of alluvial‐fan deposition. Mapping, coring and shallow seismic profiling indicate that these periods were synchronous throughout the valley and on the proximal and distal parts of the fans. From 50 to 11 ka, fan deposition ceased, a soil formed on the older alluvium and the axial drainage became active as runoff and stream competence increased. Slow deposition due to sheet flow or aeolian processes locally continued during this interval, producing cumulic soil profiles. The soil was buried by debris‐flow sediment beginning at about 11 ka, coincident with the onset of relatively dry and warm conditions in the region. However, ground‐water discharge maintained a large freshwater marsh on the valley floor throughout the Holocene. Pulses of deposition during the Holocene are recorded in the marsh and fan deposits; some pulses coincided with periods of or transitions to warm, dry climate indicated by proxy climate records, whereas others may reflect local disturbances associated with volcanism and fires. Within the marsh deposits, much of the clastic material is probably desert loess. In addition, the deposition of coppice dunes within the fan deposits coincides with two dry periods during the late Holocene.
Late‐ to post‐orogenic basins of the Pan‐African – Brasiliano collision orogen in southern Africa and southern Brazil
Authors: Gresse P. G. , Chemale F. , Da Silva L. C. , Walraven F. , Hartmann L. A.
Published: November 2003

Late‐ to post‐orogenic basins formed on both sides of the Pan‐African – Brasiliano orogen when the Congo and Kalahari Cratons collided with the Rio de la Plata Craton during the formation of western Gondwana. Trace fossil evidence and radiometric age dating indicate that deposits on both sides are coeval and span the Cambrian–Precambrian boundary.

A peripheral foreland basin, the Nama Basin, developed on the subducting southern African plate. Lower, craton‐derived fluviomarine clastics are overlain by marine platform carbonates and deltaic flysch derived in part from the rising subduction complex along the northern (Damara Belt) and western (Gariep Belt) orogenic margins. Rare, thin volcanic ash layers (tuffs and cherts) are present. Upper sediments consist of unconformable red molasse related to collisional orogenesis. Orogenic loading from the north and west led to crustal flexure and the formation of a remnant ocean that drained to the south and closed progressively from north to south. During final collision SE‐, E‐ and NE‐verging nappes overrode the active basin margins. Although younger than most of the post‐orogenic magmatism, its setting on the cratonic edge of the subducting plate precluded marked volcanism or granitic intrusion, the only exception being the youngest intrusions of the Kuboos‐Bremen Suite dated at 521±6 Ma to 491±8 Ma.

Two foreland‐type basins, perhaps faulted remnants of a much larger NE–SW elongated retroarc foreland basin, are found west of the Dom Feliciano Belt on the edge of the Rio de la Plata Craton in southern Brazil. In the southern Camaqua Basin, basal fluvial deposits are followed by cyclical marine and coarsening‐up deltaic deposits with a notable volcanic and volcaniclastic component. This lower deformed succession, comprising mainly red beds, contain stratabound Cu and Pb–Zn deposits and is overlain unconformably by a fluviodeltaic to aeolian succession of sandstones and conglomerates (with minor andesitic volcanics), derived primarily from an eastern orogenic source and showing southerly longitudinal transport. In the northern Itajaí Basin, sediments range from basal fluvial and platform sediments to fining‐up submarine fan and turbidite deposits with intercalated acid tuffs. The Brazilian basins had faulted margins off which alluvial fans were shed. They also overlie parts of the Ribeira Belt. Thrust deformation along the orogenic margin bordering the Dom Feliciano Belt was directed westward in the Camaqua and Itajaí basins, but reactivated strike‐slip and normal faults are also present. Late‐ to post‐orogenic granitoids and volcanics of the Dom Feliciano Belt, ranging in age from 568±6 Ma to 529±4 Ma, occur in the foreland basins and are geochemically related to some of the synsedimentary volcanics.
Volumetric contraction during the compaction of mudrocks: a mechanism for the development of regional‐scale polygonal fault systems
Authors: Cartwright J. A. , Lonergan L.
Published: November 2003

This paper describes the geometry and strain characteristics of a complex system of small extensional faults affecting Lower Tertiary mudrock‐dominated successions throughout the central North Sea Basin. Structural mapping using three‐dimensional seismic data shows that the fault trace geometry is polygonal. The shallow origin of the faults is confirmed by the recognition of growth sequences developed in their hangingwalls. Line balancing techniques were used to measure the extensional strain in two survey areas. This was found to be radially isotropic in the map plane. Extension in any line of section was found to vary from 6 to 19%. Since the deformation is clearly layer‐bound and there is no evidence for displacement transfer to basement structures, it is argued that the only explanation for this apparent extension is by layer‐parallel volumetric contraction. This is believed to occur in response to fluid expulsion from the mudrocks during early compaction. The conditions for failure may be achieved through increased pore fluid pressure or through tensile stresses generated as a result of pore fluid loss, or a combination of these two processes. Far‐field tectonic stresses are not considered to be responsible for the formation of this fault system.
Sedimentary sequences, seismofacies and evolution of depositional systems of the Oligo/Miocene Lower Freshwater Molasse Group, Switzerland
Authors: Schlunegger F. , Matter A. , Burbank D. W. , Leu W. , Mange M. , Màtyàs J.
Published: November 2003

ABSTRACT

Magnetostratigraphic chronologies, together with sedimentological, petrological, seismic and borehole data derived from the Oligo/Miocene Lower Freshwater Molasse Group of the North Alpine foreland basin enable a detailed reconstruction of alluvial architecture in relation to Alpine orogenic events. Six depositional systems are recorded in the Lower Freshwater Molasse Group. The bajada depositional system comprises 200–400‐m‐thick successions of ribbon channel conglomerates and overbank fines including mud‐ and debris‐flows which were derived from the Alpine border chain. The alluvial megafan depositional system is made up of massive pebble‐to‐cobble conglomerates up to 3 km thick which reveal a fan‐shaped geometry. This depositional environment grades downcurrent into the conglomerate channel belt depositional system, which comprises an ≈2‐km‐thick alternation of channel conglomerates and overbank fines. The sandstone channel belt depositional system is bordered by the 100–400‐m‐thick overbank fines assigned to the floodplain depositional system. At the feather edge of the basin, 50–400‐m‐thick lacustrine sediments in both clastic and carbonate facies represent the lacustrine depositional system.

The spatial and temporal arrangement of these depositional systems was controlled by the geometrical evolution of the Molasse Basin. During periods of enhanced sediment supply and during phases of stable sliding of the entire wedge, >2000‐m‐thick coarsening‐and thickening‐upward megasequences comprising the conglomerate channel belt, alluvial megafan and bajada depositional systems were deposited in a narrow wedge‐shaped basin. In the distal reaches of the basin, however, no sedimentary trend developed, and the basin fill comprises a <500‐m‐thick series of sandstone meander belt, floodplain and lacustrine depositional systems. During phases of accretion at the toe of the wedge, the basin widened, and prograding systems of multistorey channel sandstones extended from the thrust front to the distal reaches of the basin.

The rearrangement of the depositional systems as a function of changing orogenic conditions created discordances, which are expressed seismically by onlap and erosion of beds delimiting sedimentary sequences. Whereas stable sliding of the wedge succeeded by accretion at the toe of the wedge is recorded in the proximal Lower Freshwater Molasse by a coarsening‐and thickening‐upward megasequence followed by erosion, the opposite trend developed in the distal reaches of the Molasse. Here, fine‐grained sandstones and mudstones were deposited during periods of stable sliding, whereas phases of accretion caused a coarsening‐ and thickening‐up megasequence to form.
Impact of sediment transport efficiency on large‐scale sequence architecture: results from stratigraphic computer simulation
Authors: Rivenæs Jan C.
Published: November 2003

Our understanding of the formation of the wide range of sequence architectures we observe in the rock record is still somewhat limited. The sedimentary response to the complex interaction of various time‐variable basin‐scale processes such as subsidence, eustasy and sediment supply is difficult to understand without numerical models. The computer simulation model presented here, DEMOSTRAT, is a powerful tool to investigate the sequence development scenarios in a 2‐D dip section. The model includes tectonic subsidence, eustasy, two‐component (sand and mud) nonlinear diffusional sediment transport, compaction and isostasy. The transport coefficients in the diffusion equations express the system’s ability to transport sand and mud, and are mainly dependent on climate and subaquatic processes. Keeping other model input parameters constant, the magnitude of transport coefficients seems to have an important impact on sequence development. With high transport coefficients, extensive erosion during sea‐level fall and lack of sediment buildup above sea‐level during rise may reduce the preservation potential for nonmarine sediments. In addition, the former slope break will be eroded during transgression, forming sand‐rich slope or basin floor sediments that may be misinterpreted as lowstand fans. Moreover, the magnitude of transport coefficients has an impact on unconformity timing and development (shown in Wheeler plots).
The natural history of chronic hepatitis C in haemophiliacs
Authors: Makris M. , Preston F. E. , Rosendaal F. R. , Underwood J. C. E. , Rice K. M. , Triger D. R.
Published: November 2003

Most haemophiliacs treated with non‐virally‐inactivated clotting factor concentrates have been infected with hepatitis C virus (HCV). We have studied the natural history of chronic HCV infection by following all 138 HCV‐positive patients from our centre for periods of up to 28 years. As well as the clinical and biochemical characteristics, we studied 116 liver samples from 63 patients obtained at elective biopsy (n=103) or autopsy (n=13). 36 (26%) of the patients were HIV positive, and three were chronic carriers of hepatitis B. Evidence of previous exposure to hepatitis A and B was found in 37.2% and 48.1% respectively. Raised transaminase levels were found in 82.6% of patients. 11 of 15 patients with normal transaminases tested by PCR for HCV RNA were positive, indicating that most patients, even in this group, have chronic hepatitis C infection. Cirrhosis was diagnosed by liver histology in 19 patients, and nine patients developed liver failure. The incidence of cirrhosis rose rapidly 15 years after HCV infection to 15.6 per 1000 person‐years. Multivariate analysis showed that HIV status, length of time since HCV infection and age at HCV infection were independently associated with both the development of cirrhosis and liver failure. Two patients developed hepatocellular carcinoma; one of these was exposed only to a single batch of FVIII concentrate 11 years earlier. Chronic hepatitis C is increasingly recognized as a major cause for morbidity and mortality in haemophiliacs, especially those who are HIV positive and who were infected at an older age.