bluuebunny/crossref_metadata_2025 huggingface dataset:
Rezension des Verfahrens “Diagnose gesundheitsförderlicher Arbeit (DigA)“ von Antje Ducki
Authors: Greiner Birgit A.
Published: February 2004

Zusammenfassung. Das Instrument zur Diagnose gesundheitsförderlicher Arbeit (DigA) ist ein Fragebogen, der auf der Stresstheorie, der Handlungsregulationstheorie und auf salutogenetischen Konzepten beruht. Es erfasst Belastungen und Ressourcen der Arbeit und Merkmale der arbeitsbezogenen Gesundheit im Rahmen umfassender betrieblicher Gesundheitsförderprogramme. Die internen Konsistenzen der meisten Skalen sind gut bis zufriedenstellend, fallen jedoch z. T. unterschiedlich in verschiedenen Betrieben aus. In Bezug auf das Außenkriterium der Fehlzeiten ist das Instrument validiert. Das Verfahren kann gut für wissenschaftliche Untersuchungen zur Gesundheitsförderlichkeit von Arbeit und für praktische Zwecke der Arbeitsgestaltung eingesetzt werden. Die weitere Überarbeitung einiger weniger Skalen und zusätzliche Validierungen erscheinen notwendig.
Forschung in der Arbeits- und Organisationspsychologie: Rückblick und Ausblick
Authors: Wegge Jürgen , Kleinbeck Uwe
Published: February 2004

Zusammenfassung. Der vorliegende Diskussionsbeitrag verfolgt das Ziel, die Forschungsaktivitäten der deutschsprachigen Arbeits- und Organisationspsychologie aus den letzten zwei Jahren zu analysieren. Ziel der Synopse von 52 Zeitschriftenartikeln ist es, besondere Stärken hervorzuheben, aber auch Lücken der verfügbaren Forschung aufzudecken. Als Beurteilungskriterien werden herangezogen: Größe der Stichproben, Art der Stichprobe (Studenten, Management, Produktion, Dienstleistung, Arbeitslose, Kunden), Ort der Forschung (Labor, Feld) und Ebene der statistischen Analysen (Individuum, Dyade, Gruppe, Organisation). Ein wichtiges Ergebnis ist, dass Metaanalysen in deutschen Zeitschriften nicht zu finden sind. Es wird überwiegend im Feld geforscht. Die Stichprobengrößen variieren erheblich. Besonders häufig wird im Bereich der Dienstleistung geforscht, wobei Analysen auf der Ebene von Dyaden, Gruppen oder Organisationen stark unterrepräsentiert sind. Mehr-Ebenen-Analysen fehlen völlig. Aus dem Vergleich der Arbeiten aus der Zeitschrift für Arbeits- und Organisationspsychologie (ZAO) und der Zeitschrift für Personalpsychologie (ZPP) werden nur wenige Unterschiede sichtbar. Diese Momentaufnahme sollte in mehrerer Hinsicht zu denken geben.
Die Prognose des Berufserfolgs von Hochschulabsolventinnen und -absolventen
Authors: Abele-Brehm Andrea E. , Stief Mahena
Published: February 2004

Zusammenfassung. Die Arbeit berichtet über Ergebnisse einer Längsschnittstudie mit Hochschulabsolventinnen und -absolventen eines sehr breiten Fächerspektrums. Diese füllten unmittelbar nach dem Examen und eineinhalb Jahre später umfangreiche Fragebogen aus. Thema der Studie sind die Prognose des Berufserfolgs durch psychologische Variablen und der Geschlechtsvergleich. Die Befunde zeigen, dass gemäß den theoretischen Annahmen Einstellungen, Interessen, Selbstkonzept und Studienleistungen berufsbezogene Erwartungen und Ziele beeinflussen. Der mehr oder weniger erfolgreiche Berufseintritt wird über objektive und subjektive Indikatoren erfasst. Objektive Indikatoren des Berufserfolgs werden hypothesenkonform durch berufliche Selbstwirksamkeitserwartungen, durch berufliche Ziele, die sowohl auf intellektuelles Wachstum/Lernen, als auch auf Karriere ausgerichtet sind, und durch Instrumentalität als stereotyp maskuline Komponente des Selbstkonzepts vorhergesagt. Auch Studienfach, Leistungsparameter (insbesondere die Studiendauer) und Geschlecht sind bedeutsam. Obwohl Frauen in den relevanten psychologischen Parametern keine Unterschiede zu Männern aufweisen, steigen sie weniger erfolgreich in den Beruf ein. Die subjektive Erfolgseinschätzung wird ebenfalls durch berufliche Selbstwirksamkeitserwartungen, die Studiendauer und durch Ziele, nicht jedoch durch das Geschlecht beeinflusst.
Kuroshio intrusion and the circulation in the South China Sea
Authors: Xue Huijie , Chai Fei , Pettigrew Neal , Xu Danya , Shi Maochong , Xu Jianping
Published: February 2004

The Princeton Ocean Model is used to study the circulation in the South China Sea (SCS) and its seasonal transition. Kuroshio enters (leaves) the SCS through the southern (northern) portion of the Luzon Strait. The annually averaged net volume flux through the Luzon Strait is ∼2 Sv into the SCS with seasonal reversals. The inflow season is from May to January with the maximum intrusion of Kuroshio water reaching the western SCS during fall in compensation of summertime surface offshore transport associated with coastal upwelling. From February to April the net transport reverses from the SCS to the Pacific. The intruded Kuroshio often forms an anticyclonic current loop west of the Luzon Strait. The current loop separates near the Dongsha Islands with the northward branch continuously feeding the South China Sea Warm Current (SCSWC) near the shelf break and the westward branch becoming the South China Sea Branch of Kuroshio on the slope, which is most apparent in the fall. The SCSWC appears from December to February on the seaward side of the shelf break, flowing eastward against the prevailing wind. Diagnosis shows that the onshore Ekman transport due to northeasterly monsoon generates upwelling when moving upslope, and the particular distributions of the density and sea level associated with the cross shelf motion supports the SCSWC.
IMPACT, the LLNL 3‐D global atmospheric chemical transport model for the combined troposphere and stratosphere: Model description and analysis of ozone and other trace gases
Authors: Rotman D. A. , Atherton C. S. , Bergmann D. J. , Cameron‐Smith P. J. , Chuang C. C. , Connell P. S. , Dignon J. E. , Franz A. , Grant K. E. , Kinnison D. E. , Molenkamp C. R. , Proctor D. D. , Tannahill J. R.
Published: February 2004

We present a global chemical transport model called the Integrated Massively Parallel Atmospheric Chemical Transport (IMPACT) model. This model treats chemical and physical processes in the troposphere, the stratosphere, and the climatically critical tropopause region, allowing for physically based simulations of past, present, and future ozone and its precursors. The model is driven by meteorological fields from general circulation models (GCMs) or assimilated fields representing particular time periods. It includes anthropogenic and natural emissions, advective and convective transport, vertical diffusion, dry deposition, wet scavenging, and photochemistry. Simulations presented here use meteorological fields from the National Center for Atmospheric Research (NCAR) Middle Atmospheric Community Climate Model, Version 3 (MACCM3). IMPACT simulations of radon/lead are compared to observed vertical profiles and seasonal cycles. IMPACT results for a full chemistry simulation, with approximately 100 chemical species and 300 reactions representative of a mid‐1990s atmosphere, are presented. The results are compared with surface, satellite, and ozonesonde observations. The model calculates a total annual flux from the stratosphere of 663 Tg O3/year, and a net in situ tropospheric photochemical source (that is, production minus loss) of 161 Tg O3/year, with 826 Tg O3/year dry deposited. NOx is overpredicted in the lower midlatitude stratosphere, perhaps because model aerosol surface densities are lower than actual values or the NOx to NOy conversion rate is underpredicted. Analysis of the free radical budget shows that ozone and NOy abundances are simulated satisfactorily, as are HOx catalytic cycles and total production and removal rates for ozone.
Inverse three‐dimensional variational data assimilation for an advection‐diffusion problem: Impact of diffusion and hybrid application
Authors: Park S. K. , Kalnay E.
Published: February 2004

In this study, the performance of inverse three‐dimensional variational assimilation (I3D‐Var) is investigated in terms of dissipation process for an advection‐diffusion problem. The performance of I3D‐Var becomes poorer with larger diffusion coefficients. However, even for strong dissipation, the cost function during early iterations in the I3D‐Var decreases still much faster than it does in the standard four‐dimensional variational assimilation (4D‐Var). Based on this observation a hybrid approach that combines the I3D‐Var and the 4D‐Var is suggested to accelerate the performance of 4D‐Var. Application of this hybrid method demonstrates that the I3D‐Var can serve as a preconditioner for carrying minimization in the full 4D‐Var framework. Using the initial conditions obtained through the I3D‐Var, the 4D‐Var showed much faster convergence in minimizing the cost function.
Normal fault growth and linkage in the Whakatane Graben, New Zealand, during the last 1.3 Myr
Authors: Taylor Susanna K. , Bull Jonathan M. , Lamarche Geoffroy , Barnes Philip M.
Published: February 2004

Determination of fault growth rates and fault network evolution at timescales from 104 to 106 years has been hampered by a lack of a well‐constrained stratigraphic succession that provides a high‐fidelity record of fault development over these time periods. Here we show how seismic reflection data of different spatial resolutions can be used to constrain the linkage history and displacement rate variations of a single major fault. We present data collected in the offshore Whakatane Graben, Bay of Plenty, New Zealand, where intense normal faulting occurs as a result of active back extension. The focus of our study is the Rangitaiki Fault, a linked segmented normal fault which is the dominant active structure in the graben. The total linked fault length is ∼20 km and has a displacement of up to 830 ± 130 m in the top 1.5 km of sediments. The fault has been actively growing for the last 1.34 ± 0.51 Myr and has developed from isolated fault segments to a fully linked fault system. Initially, the dominant process of fault growth was tip propagation, with an average and maximum displacement rates of 0.52 ± 0.18 and 0.72 ± 0.23 mm yr−1, respectively. Interaction and linkage became more significant as the fault segments grew toward each other, resulting in the fault network becoming fully linked between 300 and 18 ka. Following fault segment linkages, the average displacement rate of the fault network increased by almost threefold to 1.41 ± 0.31 mm yr−1, while the maximum displacement rate increased to 3.4 ± 0.2 mm yr−1. This is the first time that the growth rate of unlinked fault segments has been resolved and has been shown to be slower than in the subsequent linked fault system.
A statistical model for the timing of earthquakes and volcanic eruptions influenced by periodic processes
Authors: Jupp Tim E. , Pyle David M. , Mason Ben G. , Dade W. Brian
Published: February 2004

Evidence of nonuniformity in the rate of seismicity and volcanicity has been sought on a variety of timescales ranging from ∼12.4 hours (tidal) to 103–104 years (climatic), but the results are mixed. Here, we propose a simple conceptual model for the influence of periodic processes on the frequency of geophysical “failure events” such as earthquakes and volcanic eruptions. In our model a failure event occurs at a “failure time” tF = tI + tR which is controlled by an “initiation event” at the “initiation time” tI and by the “response time” of the system tR. We treat each of the initiation time, the response time, and the failure time as random variables. In physical terms, we define the initiation time to be the time at which a “load function” exceeds a “strength function,” and we imagine that the response time tR corresponds to a physical process such as crack propagation or the movement of magma. Assuming that the magnitude and frequency of the periodic process are known, we calculate the statistical distribution of the initiation times on the assumption that the load and strength functions are otherwise linear in time. This allows the distribution of the failure times to be calculated if the distribution of the response times is known also. The quantitative predictions of this simple theory are compared with some examples of observed periodicity in seismic and volcanic activity at tidal and annual timescales.
Three‐dimensional architecture of the Nankai accretionary prism's imbricate thrust zone off Cape Muroto, Japan: Prism reconstruction via en echelon thrust propagation
Authors: Gulick S. P. S. , Bangs N. L. B. , Shipley T. H. , Nakamura Y. , Moore G. , Kuramoto S.
Published: February 2004

A 9 km wide, 92 km long, three‐dimensional (3‐D) seismic reflection volume acquired off Shikoku Island, Japan, images the seaward portion of the subduction of the Philippine Sea plate at the Nankai Trough and Nankai accretionary prism. Detailed interpretation of the imbricate thrust and protothrust zones, the portions of the prism between the deformation front and the first out‐of‐sequence thrust, shows a high degree of variability in the thrust faults that all parallel the frontal thrust but are arranged in en echelon patterns along strike and frequently include complications such as piggyback faults and fault splays. Interestingly, the sinuous seafloor morphology of the prism does not accurately reflect the en echelon 3‐D architecture of the primary prism thrusts. Seafloor morphology appears to average across several thrusts along strike and is further modified by near‐surface thrust splays and backthrusts, suggesting that care must be taken in interpreting seafloor relief in terms of lateral continuity or thrust fault geometry. Subduction of the Kinan seamounts 20 km northeast of the center of the Muroto 3‐D volume generated a scallop‐shaped embayment in the prism; the rebuilding process appears to influence the northeastern portion of the 3‐D volume where a ∼625 m landward step in the position of the frontal thrust and numerous changes in prism architecture are observed. These observations imply that accretionary prisms may reattain equilibrium following seamount subduction by lateral en echelon fault propagation into damaged zones that facilitate an increase accretion rate until a laterally continuous deformation front is reestablished.
Interseismic strain and rotation rates in the northeast Mojave domain, eastern California
Authors: Savage J. C. , Svarc J. L. , Prescott W. H.
Published: February 2004

The northeast Mojave domain, a type locality for bookshelf faulting, is a region of east striking, left‐lateral faults in the northeast corner of the Mojave block, a block otherwise dominated by ∼N40°W striking, right‐lateral faults. Paleomagnetic evidence suggests that blocks within the domain have rotated clockwise about a vertical axis as much as 60° since 12.8 Ma [Schermer et al., 1996]. In 1994, and again in 2002, the U.S. Geological Survey surveyed an array of 14 geodetic monuments distributed across the northeast Mojave domain. The 2002 survey results were adjusted to remove the coseismic offsets imposed by the nearby Hector Mine earthquake (16 October 1999, Mw = 7.1). The adjusted deformation across the array appears to be uniform and can be approximated by the principal strain rates ε1 = 28.9 ± 9.1 N77.2°W ± 4.8° and ε2 = −48.2 ± 8.9 N12.8°E ± 4.8° nstrain yr−1; extension reckoned positive, and quoted uncertainties are standard deviations. That strain accumulation could be released by slip on faults striking N32°W but not by bookshelf faulting on the east striking faults alone. The vertical axis rotation rate of the northeast Mojave domain as a whole relative to fixed North America is 71.0 ± 6.4 nrad yr−1 (4.07° ± 0.37° Myr−1) clockwise, about twice the maximum tensor shear strain rate. The observed rotation rate acting over 12.8 Myr would produce a clockwise rotation of 52.1° ± 4.7°, exclusive of possible coseismic rotations. That rotation is in rough agreement with the paleomagnetic rotation accumulated in the individual fault blocks within the northeast Mojave domain since 12.8 Ma.
Climatology of katabatic winds in the McMurdo dry valleys, southern Victoria Land, Antarctica
Authors: Nylen Thomas H. , Fountain Andrew G. , Doran Peter T.
Published: February 2004

Katabatic winds dramatically affect the climate of the McMurdo dry valleys, Antarctica. Winter wind events can increase local air temperatures by 30°C. The frequency of katabatic winds largely controls winter (June to August) temperatures, increasing 1°C per 1% increase in katabatic frequency, and it overwhelms the effect of topographic elevation (lapse rate). Summer katabatic winds are important, but their influence on summer temperature is less. The spatial distribution of katabatic winds varies significantly. Winter events increase by 14% for every 10 km up valley toward the ice sheet, and summer events increase by 3%. The spatial distribution of katabatic frequency seems to be partly controlled by inversions. The relatively slow propagation speed of a katabatic front compared to its wind speed suggests a highly turbulent flow. The apparent wind skip (down‐valley stations can be affected before up‐valley ones) may be caused by flow deflection in the complex topography and by flow over inversions, which eventually break down. A strong return flow occurs at down‐valley stations prior to onset of the katabatic winds and after they dissipate. Although the onset and termination of the katabatic winds are typically abrupt, elevated air temperatures remain for days afterward. We estimate that current frequencies of katabatic winds increase annual average temperatures by 0.7° to 2.2°C, depending on location. Seasonally, they increase (decrease) winter average temperatures (relative humidity) by 0.8° to 4.2° (−1.8 to −8.5%) and summer temperatures by 0.1° to 0.4°C (−0.9% to −4.1%). Long‐term changes of dry valley air temperatures cannot be understood without knowledge of changes in katabatic winds.
Single particle measurements of the chemical composition of cirrus ice residue during CRYSTAL‐FACE
Authors: Cziczo D. J. , Murphy D. M. , Hudson P. K. , Thomson D. S.
Published: February 2004

The first real‐time, in situ, investigation of the chemical composition of the residue of cirrus ice crystals was performed during July 2002. This study was undertaken on a NASA WB‐57F high‐altitude research aircraft as part of CRYSTAL‐FACE, a field campaign which sought to further our understanding of the relation of clouds, water vapor, and climate by characterizing, among other parameters, anvil cirrus formed about the Florida peninsula. A counter flow virtual impactor (CVI) was used to separate cirrus ice from the unactivated interstitial aerosol particles and evaporate condensed‐phase water. Residual material, on a crystal‐by‐crystal basis, was subsequently analyzed using the NOAA Aeronomy Laboratory's Particle Analysis by Laser Mass Spectrometry (PALMS) instrument. Sampling was performed from 5 to 15 km altitude and from 12° to 28° north latitude within cirrus originating over land and ocean. Chemical composition measurements provided several important results. Sea salt was often incorporated into cirrus, consistent with homogeneous ice formation by aerosol particles from the marine boundary layer. Size measurements showed that large particles preferentially froze over smaller ones. Meteoritic material was found within ice crystals, indicative of a relation between stratospheric aerosol particles and tropospheric clouds. Mineral dust was the dominant residue observed in clouds formed during a dust transport event from the Sahara, consistent with a heterogeneous freezing mechanism. These results show that chemical composition and size are important determinants of which aerosol particles form cirrus ice crystals.
Variation on the atmospheric concentrations of biogenic carbonyl compounds and their removal processes in the northern forest at Moshiri, Hokkaido Island in Japan
Authors: Matsunaga Sou , Mochida Michihiro , Kawamura Kimitaka
Published: February 2004

Biogenic aldehydes, hydroxycarbonyls, and dicarbonyls in gas and particle phases were collected with an annular denuder sampling system (ADSS) in a Quercus crispula and Picea glehnii mast mixed forest. Eighty samples were collected from 22 to 29 August 2002. The size distributions of aerosols were also observed concurrently with a scanning mobility particle sizer (SMPS). The gaseous concentrations of these carbonyl compounds ranged from the detection limit (approximately 1 pptv) to 154 pptv (630 ng m−3, 4‐oxopentanal), and the particulate concentrations ranged from the detection limit (approximately 3 ng m−3) to 200 ng m−3 (4‐oxopentanal). Although the production processes of these compounds are different from each other, the temporal variations of the gaseous concentrations were quite similar. In addition, the variation was also similar to that of the ambient temperature. Furthermore, gas‐to‐particle conversion was suggested to be an important removal process of these compounds. We could evaluate the importance of the gas‐to‐particle conversion as a removal process of the gaseous species by an ADSS measurement. In addition, the results of our experiment indicated that the conversion includes two processes. The first is an adsorption onto the aerosols which have already existed in the atmosphere. The next is dissolution into the water phases in the aerosols. The latter process was particular to water soluble compounds. The measurement allowed us to identify the most likely removal processes of biogenic semivolatile organic compounds (SOCs). In this study, we discuss about these processes of semivolatile and biogenic carbonyls in the forest atmosphere.
eIF4E isoform 2 in Schizosaccharomyces pombe is a novel stress‐response factor
Authors: Ptushkina Marina , Malys Naglis , McCarthy John E G
Published: February 2004

Cap‐binding proteins of the eIF4E family are generally involved in mediating ribosome recruitment to capped mRNA via an interaction with the initiation factor eIF4G. However, Schizosaccharomyces pombe has two eIF4E isoforms, one of which (eIF4E2, encoded by tif452) has a relatively low affinity for eIF4G. We show that tif452 is required for specific stress responses. An S. pombe, tif452Δ mutant manifests slow growth under conditions of nutrient, temperature and salt stress. eIF4E2 shows a distinct subcellular distribution to eIF4E1, the cap‐binding factor that is required for mainstream translation. In response to salt stress, the cellular level of eIF4E2 increases, whereas the amount of intact eIF4G decreases, leaving eIF4E2 as the predominant eIF4E isoform in a cell deficient in eIF4G. The presence of eIF4E2 modifies the competence of S. pombe ribosomes to translate mRNAs with structured leaders in vivo. The tif452 promoter has putative stress‐response (T‐rich) motifs, whereas eIF4E2 seems to be a new type of stress‐response factor.
The yeast coexpression network has a small‐world, scale‐free architecture and can be explained by a simple model
Authors: van Noort Vera , Snel Berend , Huynen Martijn A
Published: February 2004

We investigated the gene coexpression network inSaccharomyces cerevisiae, in which genes are linked when they are coregulated. This network is shown to have a scale‐free, small‐world architecture. Such architecture is typical of biological networks in which the nodes are connected when they are involved in the same biological process. Current models for the evolution of intracellular networks do not adequately reproduce the features that we observe in the network. We therefore derive a new model for its evolution based on the observation that there is a positive correlation between the sequence similarity of paralogues and their probability of coexpression or sharing of transcription factor binding sites (TFBSs). The simple, neutralist's model consists of (1) coduplication of genes with their TFBSs, (2) deletion and duplication of individual TFBSs and (3) gene loss. A network is constructed by connecting genes that share multiple TFBSs. Our model reproduces the scale‐free, small‐world architecture of the coregulation network and the homology relations between coregulated genes without the need for selection either at the level of the network structure or at the level of gene regulation.
Molecular insights into the interaction of PYM with the Mago–Y14 core of the exon junction complex
Authors: Bono Fulvia , Ebert Judith , Unterholzner Leonie , Güttler Thomas , Izaurralde Elisa , Conti Elena
Published: February 2004

The exon junction complex (EJC) is deposited on mRNAs as a consequence of splicing and influences postsplicing mRNA metabolism. The Mago–Y14 heterodimer is a core component of the EJC. Recently, the protein PYM has been identified as an interacting partner of Mago–Y14. Here we show that PYM is a cytoplasmic RNA‐binding protein that is excluded from the nucleus by Crm1. PYM interacts directly with Mago–Y14 by means of its N‐terminal domain. The crystal structure of the Drosophila ternary complex at 1.9 Å resolution reveals that PYM binds Mago and Y14 simultaneously, capping their heterodimerization interface at conserved surface residues. Formation of this ternary complex is also observed with the human proteins. Mago residues involved in the interaction with PYM have been implicated in nonsense‐mediated mRNA decay (NMD). Consistently, human PYM is active in NMD tethering assays. Together, these data suggest a role for PYM in NMD.
Structure of the conserved domain of ANAC, a member of the NAC family of transcription factors
Authors: Ernst Heidi A , Nina Olsen Addie , Skriver Karen , Larsen Sine , Lo Leggio Leila
Published: February 2004

The structure of the DNA‐binding NAC domain of Arabidopsis ANAC (abscisic‐acid‐responsive NAC) has been determined by X‐ray crystallography to 1.9 Å resolution (Protein Data Bank codes 1UT4 and 1UT7). This is the first structure determined for a member of the NAC family of plant‐specific transcriptional regulators. NAC proteins are characterized by their conserved N‐terminal NAC domains that can bind both DNA and other proteins. NAC proteins are involved in developmental processes, including formation of the shoot apical meristem, floral organs and lateral shoots, as well as in plant hormonal control and defence. The NAC domain does not possess a classical helix–turn–helix motif; instead it reveals a new transcription factor fold consisting of a twisted β‐sheet surrounded by a few helical elements. The functional dimer formed by the NAC domain was identified in the structure, which will serve as a structural template for understanding NAC protein function at the molecular level.
Convergent evolution of gene networks by single‐gene duplications in higher eukaryotes
Authors: Amoutzias Gregory D , Robertson David L , Oliver Stephen G , Bornberg‐Bauer Erich
Published: February 2004

By combining phylogenetic, proteomic and structural information, we have elucidated the evolutionary driving forces for the gene‐regulatory interaction networks of basic helix–loop–helix transcription factors. We infer that recurrent events of single‐gene duplication and domain rearrangement repeatedly gave rise to distinct networks with almost identical hub‐based topologies, and multiple activators and repressors. We thus provide the first empirical evidence for scale‐free protein networks emerging through single‐gene duplications, the dominant importance of molecular modularity in the bottom‐up construction of complex biological entities, and the convergent evolution of networks.
Error in shear‐wave polarization and time splitting
Authors: Michaud Gwénola , Snieder Roel
Published: February 2004

Shear‐wave polarization and time delay are attributes commonly used for fracture detection and characterization. In time‐lapse analysis these parameters can be used as indicators of changes in the fracture orientation and density. Indeed, changes in fracture characteristics provide key information for increased reservoir characterization and exploitation. However, relative to the data uncertainty, is the comparison of these parameters over time statistically meaningful? We present the uncertainty in shear‐wave polarization and time delay as a function of acquisition uncertainties, such as receiver and source misorientation, miscoupling and band‐limited random noise. This study is applied to a time‐lapse borehole seismic survey, recorded in Vacuum Field, New Mexico. From the estimated uncertainties for each survey, the uncertainty in the difference between the two surveys is 31° for the shear‐wave polarization angle and 4 ms for the shear‐wave time delay. Any changes in these parameters greater than these error estimates can be interpreted with confidence. This analysis can be applied to any time‐lapse measurement to provide an interval of confidence in the interpretation of shear‐wave polarization angles and time splitting.
Effect of grain scale alignment on seismic anisotropy and reflectivity of shales
Authors: Arne Johansen Tor , Ole Ruud Bent , Jakobsen Morten
Published: February 2004

The elastic properties and anisotropy of shales are strongly influenced by the degree of alignment of the grain scale texture. In general, an orientation distribution function (ODF) can be used to describe this alignment, which, in practice, can be characterized by two Legendre coefficients. We discuss various statistical ODFs that define the alignment by spreading from a mean value; in particular, the Gaussian, Fisher and Bingham distributions. We compare the statistical models with an ODF resulting from pure vertical compaction (no shear strain) of a sediment. The compaction ODF may be used to estimate how the elastic properties and anisotropy evolve due to burial of clayey sediments.

Our study shows that the three statistical ODFs produce almost identical correspondence between the two Legendre coefficients as a function of the spreading parameter, so that the spreading parameter of one ODF can be converted to the spreading parameter of another ODF. In most cases it is then sufficient to apply the spreading parameter for the ODF instead of the two Legendre coefficients. The effect of compaction on the ODF gives a slightly different correspondence between the two Legendre coefficients from that for the other models. In principle, this opens up the possibility of distinguishing anisotropy effects due to compaction from those due to other processes.

We also study reflection amplitudes versus angle of incidence (AVA) for all wave modes, where shales having various ODFs overlie an isotropic medium. The AVA responses are modelled using both exact and approximation formulae, and their intercepts and gradients are compared. The modelling shows that the S‐wave velocity is sensitive to any perturbation in the spreading parameter, while the P‐wave velocity becomes increasingly sensitive to a perturbation of a less ordered system. Similar observations are found for the AVA of the P‐P and P‐SV waves. Modelling indicates that a combined use of the amplitude versus offset of P‐P and P‐SV reflected waves may reveal certain grain scale alignment properties of shale‐like rocks.
A comparison of receiver technologies in borehole MMR and EM surveys
Authors: Elders J.A. , Asten M.W.
Published: February 2004

A series of downhole magnetometric resistivity (DHMMR) and downhole electromagnetic (DHEM) surveys were conducted near Broken Hill, New South Wales, Australia, and at Zinkgruvan, Sweden, to determine how probe and receiver equipment choices affect the amount of noise visible in borehole MMR and EM data. Noise analyses performed on the data, using the standard deviation to gauge the relative noise levels between different probes and receiver systems, indicate that high noise levels in MMR data result primarily from the use of a three‐component EM probe, which has a reduced effective area and hence a higher noise floor compared with a single‐component EM probe. High noise, attributable to cultural sources such as nearby power lines, in either MMR or EM data can be reduced through the use of full‐waveform, multipurpose receiver systems. These systems allow for the use of tapered stacking, which is a more effective method of eliminating coherent noise associated with power‐line transients than the boxcar‐stacking method used by traditional receiver systems.
Comparison of the virulence of Armillaria cepistipes and Armillaria ostoyae on four Norway spruce provenances
Authors: Prospero S. , Holdenrieder O. , Rigling D.
Published: February 2004

The basidiomycetes Armillaria cepistipes and Armillaria ostoyae frequently occur in the same forest stand. In this study, we determined the virulence of 20 isolates of A. cepistipes and 16 isolates of A. ostoyae on four different provenances of 2‐year‐old Norway spruce (Picea abies). Within 30 months after inoculation, 1.1 and 19.1% of the seedlings inoculated with A. cepistipes and A. ostoyae, respectively, had died or were dying. The incidence of dead and dying seedlings varied between 3 and 49% among the A. ostoyae isolates. The virulence of an isolate was positively correlated to its ability to produce rhizomorphs. One Norway spruce provenance showed significantly lower susceptibility to A. ostoyae than the other three. Rhizomorphs of both Armillaria species were attached to the root surface. The attached rhizomorphs of A. ostoyae, however, were associated with significantly more lesions. The virulence of the isolates was not correlated with their wood‐degrading capability for either of the Armillaria species.
Sphaceloma murrayae Jenk. & Grods., a pathogen new to Europe on Salix spp.
Authors: Butin H. , Kehr R.
Published: February 2004

A Sphaceloma species causing greyish‐white leaf spots of several Salix species is described and illustrated. This is the first record for Europe of the mitosporic fungus identified as Sphaceloma murrayae, which was formerly known to occur only in New Zealand, Argentina and the US. In addition to information on symptoms and hosts, similar fungi occurring on willow, which can be confused with the new fungus are also discussed.
Rhizomorph growth habit, saprophytic ability and virulence of 15 Armillaria species
Authors: Morrison D. J.
Published: February 2004

The rhizomorph branching habit in soil, competitive saprophytic ability and virulence were determined for 15 species of Armillaria from Europe, North America and Australia and New Zealand. In soil, rhizomorphs of northern hemisphere species branched either monopodially or dichotomously, whereas all five species from Australia and New Zealand branched dichotomously. The dry weight of rhizomorphs produced in soil by isolates of a species and by species was very variable. Species with monopodially branched rhizomorphs had significantly higher saprophytic colonization scores than dichotomously branched species and scores were significantly higher in Garry oak than Douglas‐fir segments and in fresh than autoclaved segments. The damage to Douglas‐fir seedlings caused by isolates of most dichotomously branched species was significantly greater than that caused by monopodially branched species. Species producing dichotomously branched rhizomorphs were more aggressive than monopodially branched species, killing 80% (vs. 17%) of seedlings that died during the first year of the 2‐year experiment.
Effects of hot water treatment, biocontrol agents, disinfectants and a fungicide on storability of English oak acorns and control of the pathogen,Ciboria batschiana
Authors: Knudsen I. M. B. , Thomsen K. A. , Jensen B. , Poulsen K. M.
Published: February 2004

Eight biological control agents (BCAs;Clonostachys rosea,Trichoderma harzianum,Trichoderma polysporum,Phlebiopsis gigantea,Bacillus subtilis,Pseudomonas chlororaphis,Streptomyces griseoviridis), five disinfectants and a fungicide (Prochloras‐ManganTM) were evaluated for the control of harmful mycoflora onCiboria batschiana‐infected English oak (Quercus robur) acorns during storage at −1°C. All treatments were tested on both hot water‐treated (HW) and untreated acorns. HW‐treated acorns generally stored better than untreated acorns as a result of elimination ofC. batschiana. The HW treatment increased the germination percentage before storage from 60 to 85%. Germination of HW‐treated acorns decreased from 85 to 40% after 16.5 months of storage, whereas germination of untreated acorns decreased from 60 to 20% after a similar time.Ciboria batschianainfection of untreated acorns increased from 14% before storage to 55% after 16 months of storage. All disinfectants and BCAs had a positive effect on viability and particularly on control ofC. batschianain untreated acorns. Best control ofC. batschianaoccurred withC. rosea, MycostopTM(S. griseoviridis), Binab TFTM(T. polysporum + T. harzianum), andP. chlororaphis. For HW‐treated acorns, there was only a small effect of BCAs on acorn viability while the fungicide and the disinfectants had no effect. Treatments also affected the saprophytic mycoflora with the HW treatment reducing the frequency ofCladosporiumspp. andPapulasporaspp., but enhancingAlternariaspp.,MucoraceaeandPenicilliumspp. However, when combined with HW treatment, several BCAs significantly reduced the prevalence of these fungi. Also,C. roseareduced the growth ofFusariumspp. Significant negative correlations (p < 0.001) were found between acorn germination and certain storage fungi such asAcremoniella atra,Cladosporiumspp. and dematiaceous mycelia.
Intraneuronal amyloid‐β1‐42 production triggered by sustained increase of cytosolic calcium concentration induces neuronal death
Authors: Pierrot Nathalie , Ghisdal Philippe , Caumont Anne‐Sophie , Octave Jean‐Noël
Published: February 2004

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the presence in the brain of senile plaques which contain an amyloid core made of β‐amyloid peptide (Aβ). Aβ is produced by the cleavage of the amyloid precursor protein (APP). Since impairment of neuronal calcium signalling has been causally implicated in ageing and AD, we have investigated the influence of an influx of extracellular calcium on the metabolism of human APP in rat cortical neurones. We report that a high cytosolic calcium concentration, induced by neuronal depolarization, inhibits the α‐secretase cleavage of APP and triggers the accumulation of intraneuronal C‐terminal fragments produced by the β‐cleavage of the protein (CTFβ). Increase in cytosolic calcium concentration specifically induces the production of large amounts of intraneuronal Aβ1‐42, which is inhibited by nimodipine, a specific antagonist of l‐type calcium channels. Moreover, calcium release from endoplasmic reticulum is not sufficient to induce the production of intraneuronal Aβ, which requires influx of extracellular calcium mediated by the capacitative calcium entry mechanism. Therefore, a sustained high concentration of cytosolic calcium is needed to induce the production of intraneuronal Aβ1‐42 from human APP. Our results show that this accumulation of intraneuronal Aβ1‐42 induces neuronal death, which is prevented by a functional γ‐secretase inhibitor.
Long‐lasting acetylcholinesterase splice variations in anticholinesterase‐treated Alzheimer's disease patients
Authors: Darreh‐Shori T. , Hellström‐Lindahl E. , Flores‐Flores C. , Guan Z. Z. , Soreq H. , Nordberg A.
Published: February 2004

Protein levels of different acetylcholinesterase (AChE) splice variants were explored by a combination of immunoblot techniques, using two different antibodies, directed against the C‐terminus of the AChE‐R splice variant or the core domain common to all variants. Both AChE‐R and AChE‐S splice variants as well as several heavier AChE complexes were detected in brain homogenates from the parietal cortex of patients with or without Alzheimer's disease (AD) as well as the cerebrospinal fluid (CSF) of AD patients, compatible with the assumption that CSF AChEs might originate from CNS neurons. Long‐term changes in the composition of CSF AChE variants were further pursued in AD patients treated with rivastigmine (n = 11) or tacrine (n = 17) in comparison to untreated AD patients (n = 5). In untreated patients, AChE‐R was markedly reduced as compared with the baseline level (37%), whereas the medium size AChE‐S complex was increased by 32%. Intriguingly, tacrine produced a general and profound up‐regulation of all detected AChE variants (up to 117%), whereas rivastigmine treatment caused a mild and selective up‐regulation of AChE‐R (∼10%, p < 0.05). Moreover, the change in the ratio of AChE‐R to AChE‐S (R/S‐ratio) strongly and positively correlated with sustained cognition at 12 months (p < 0.0001). Thus, evaluation of changes in the composition of CSF AChE variants may yield important information referring to the therapeutic efficacy and/or development of drug tolerance in AD patients treated with anti‐cholinesterases.
A restrictive element 1 (RE‐1) in the VIP gene modulates transcription in neuronal and non‐neuronal cells in collaboration with an upstream tissue specifier element
Authors: Hamelink Carol , Hahm Sung Ho , Huang Heather , Eiden Lee E.
Published: February 2004

The vasoactive intestinal peptide (VIP) gene has been studied extensively as a prototype neuronal gene containing multiple cis‐active elements that confer responsiveness to cell lineage, neurotrophic, and activity‐dependent intrinsic and extrinsic cues. However, reporter genes containing the presumptive complete regulatory region 5′ to the start of transcription do not confer tissue‐specific gene expression in vivo. We therefore sought cis‐regulatory elements downstream of the transcriptional start that might confer additional tissue‐specific and tissue‐restrictive properties to the VIP transcriptional unit. We report here a repressor element, similar to the canonical restrictive element‐1 (RE‐1), located within the first non‐coding exon of the human VIP gene. The ability of this element to regulate VIP reporter gene expression in neuroblastoma and fibroblastic cells was examined. Endogenous VIP expression is high in SH‐EP neuroblastoma cells, low but inducible in SH‐SY5Y cells, and absent in HeLa cells. Endogenous RE‐1 silencer factor (REST) expression was highest in SH‐EP and HeLa cells, and significantly lower in SH‐SY5Y cells. Transient transfection of a VIP reporter gene containing a mutated RE‐1 sequence revealed an RE‐1‐dependent regulation of VIP gene expression in all three cell types, with regulation greatest in cells (SH‐EP, HeLa) with highest levels of REST expression. Serial truncation of the VIP reporter gene further revealed a specific interaction between the RE‐1 and a tissue‐specifier element located 5 kb upstream in the VIP gene. Thus, REST can regulate VIP gene expression in both neuroblastic and non‐neuronal cells, but requires coupling to the upstream tissue specifier element.
Region‐specific generation of functional neurons from naive embryonic stem cells in adult brain
Authors: Harkany Tibor , Andäng Michael , Kingma Hylke Jan , Görcs Tamás J. , Holmgren Carl D. , Zilberter Yuri , Ernfors Patrik
Published: February 2004

Embryonic stem (ES) cells are multipotent progenitors with unlimited developmental potential, and in vitro differentiated ES cell‐derived neuronal progenitors can develop into functional neurons when transplanted in the central nervous system. As the capacity of naive primary ES cells to integrate in the adult brain and the role of host neural tissue therein are yet largely unknown, we grafted low densities of undifferentiated mouse ES (mES) cells in adult mouse brain regions associated with neurodegenerative disorders; and we demonstrate that ES cell‐derived neurons undergo gradual integration in recipient tissue and acquire morphological and electrophysiological properties indistinguishable from those of host neurons. Only some brain areas permitted survival of mES‐derived neural progenitors and formed instructive environments for neuronal differentiation and functional integration of naive mES cells. Hence, region‐specific presence of microenvironmental cues and their pivotal involvement in controlling ES cell integration in adult brain stress the importance of recipient tissue characteristics in formulating cell replacement strategies for neurodegenerative disorders.
Gene expression profile of the nucleus accumbens of human cocaine abusers: evidence for dysregulation of myelin
Authors: Albertson Dawn N. , Pruetz Barb , Schmidt Carl J. , Kuhn Donald M. , Kapatos Gregory , Bannon Michael J.
Published: February 2004

Chronic cocaine abuse induces long‐term neural adaptations as a consequence of alterations in gene expression. This study was undertaken to identify those transcripts differentially regulated in the nucleus accumbens of human cocaine abusers. Affymetrix microarrays were used to measure transcript abundance in 10 cocaine abusers and 10 control subjects matched for age, race, sex, and brain pH. As expected, gene expression of cocaine‐ and amphetamine‐regulated transcript (CART) was increased in the nucleus accumbens of cocaine abusers. The most robust and consistent finding, however, was a decrease in the expression of a number of myelin‐related genes, including myelin basic protein (MBP), proteolipid protein (PLP), and myelin‐associated oligodendrocyte basic protein (MOBP). The differential expression seen by microarray for CART as well as MBP, MOBP, and PLP was verified by RT–PCR. In addition, immunohistochemical experiments revealed a decrease in the number of MBP‐immunoreactive oligodendrocytes present in the nucleus accumbens and surrounding white matter of cocaine abusers. These findings suggest a dysregulation of myelin in human cocaine abusers.
D1 dopamine receptor stimulation increases the rate of AMPA receptor insertion onto the surface of cultured nucleus accumbens neurons through a pathway dependent on protein kinase A
Authors: Mangiavacchi Simona , Wolf Marina E.
Published: February 2004

Trafficking of α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate (AMPA) receptors is an important determinant of synaptic strength. Our prior work suggests that D1 dopamine (DA) receptors regulate AMPA receptor trafficking. This is a possible mechanism by which amphetamine and cocaine, which indirectly stimulate D1 receptors, may alter synaptic strength in addiction‐related neuronal circuits. Post‐natal rat nucleus accumbens (NAc) cultures were used to study the role of protein kinase A (PKA) in D1 receptor regulation of the surface expression of the AMPA receptor subunit GluR1. Using an immunocytochemical assay that selectively detects newly externalized GluR1, we found that the rate of GluR1 externalization is enhanced by the D1 agonist SKF 81297 (100 nm‐1 µm). This was blocked by a D1 receptor antagonist (SCH 23390; 10 µm) and by two different cell‐permeable PKA inhibitors, KT5720 (2 and 10 µm) and RpcAMPS (10 µm). Conversely, the PKA activator SpcAMPS increased the rate of GluR1 externalization in a concentration‐dependent manner. A maximally effective concentration of SpcAMPS (10 µm) occluded the effect of SKF 81297 (1 µm) on GluR1 externalization. Using similar cultures, we showed previously that D1 receptor stimulation increases GluR1 phosphorylation at the PKA site. Together, our findings suggest that PKA phosphorylation of GluR1 is required for GluR1 externalization in response to D1 receptor stimulation.