bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison results and steady states for the Fujita equation with fractional Laplacian
Authors: López-Mimbela José Alfredo , Birkner Matthias , Wakolbinger Anton
Published: August 2004

We study a semilinear PDE generalizing the Fujita equation whose evolution operator is the sum of a fractional power of the Laplacian and a convex non-linearity. Using the Feynman–Kac representation we prove criteria for asymptotic extinction versus finite time blow up of positive solutions based on comparison with global solutions. For a critical power non-linearity we obtain a two-parameter family of radially symmetric stationary solutions. By extending the method of moving planes to fractional powers of the Laplacian we prove that all positive steady states of the corresponding equation in a finite ball are radially symmetric.

Nous étudions une équation de réaction-diffusion semilinéaire (généralisant l'équation de Fujita), dont l'opérateur d'évolution est la somme d'une puissance fractionnelle du Laplacien et d'une non-linéarité convexe. A l'aide de la représentation de Feynman–Kac nous exhibons des critères entrainant l'extinction asymptotique, respectivement l'explosion en temps fini, de solutions positives. Ces critères s'obtiennent en comparant avec des solutions globales. Pour une certaine puissance critique de la non-linéarité nous obtenons une famille paramétrisée de solutions stationnaires à symétrie radiale. Par extension de la méthode de déplacement d'hyperplans à des puissances fractionnelles du Laplacien, nous prouvons que toute solution positive stationnaire de l'équation correspondante dans une boule finie comporte une symétrie radiale.
Identification and characterization of a novel Δ12‐fatty acid desaturase gene from Rhizopus arrhizus
Authors: Wei Dongsheng , Li Mingchun , Zhang Xinxin , Ren Yong , Xing Laijun
Published: August 2004

Based on the sequence information of Δ12‐fatty acid desaturase genes (from Mucor circinelloides, Mortierella alpina, Mucor rouxii and Aspergillus nidulans), which were involved in the conversion from C18:1 to C18:2, a cDNA sequence putatively encoding a Δ12‐fatty acid desaturase was isolated from Rhizopus arrhizus using the combination of reverse transcription‐polymerase chain reaction (RT‐PCR) and rapid amplification of cDNA ends (RACE) methods. Sequence analysis indicated that it had an open reading frame (ORF) of 1170 bp, coding for 389 amino acid residues of 45 kDa, pI of the deduced protein was 7.01. The deduced amino acid sequence of this cloned cDNA showed high identity to those filamentous fungal Δ12‐desaturases mentioned above, including three conserved histidine‐rich motifs and two hydrophobic domains. Functional identification was done heterologously in Saccharomyces cerevisiae strain INVScl. The result demonstrated that the deduced amino acid sequence exhibited Δ12‐fatty acid desaturase activity, sugguesting that this gene encoded for a membrane‐bound desaturase, Δ12‐fatty acid desaturase.
Purification and expression of a processing protease on β‐alanine‐oxoglutarate aminotransferase from rat liver mitochondria
Authors: Ohyama Tomoko , Matsuda Koichi , Tachibana Hideyuki , Fujimoto Sakata Shigeko , Mori Masataka , Horiuchi Masahisa , Tamaki Nanaya
Published: August 2004

GABA[arrow beta]AlaAT convertase is an endopeptidase that processes brain‐type 4‐aminobutyrate aminotransferase (GABA AT; EC 2.6.1.19) to liver‐type β‐alanine‐oxoglutarate aminotransferase (β‐AlaAT I) in rats. Its molecular mass was 180 kDa as determined by gel filtration. A subunit molecular mass of 97 652 Da was measured using MALDI‐TOF MS. The N‐terminal sequence of the purified GABA[arrow beta]AlaAT convertase was SRVEVSKVLILGSGGLSIGQAGEFDYSGSQAV‐ and was identical to residues 418–449 of carbamoyl‐phosphate synthetase I (CPS I; EC 1.2.1.27) purified from rat liver. The subunit molecular mass and the N‐terminal amino acid sequence suggested that GABA[arrow beta]AlaAT convertase was the 418–1305 peptide of CPS I. An expression vector containing the coding region of the 418–1305 peptide of rat CPS I was transfected into NIH3T3 cells and the extract of the cells showed GABA[arrow beta]AlaAT convertase activity.
Developmental Effects in 2D Versus 3D Versions in Verticality and Horizontality Tasks
Authors: Baldy René , Devichi Claude , Chatillon Jean-Francisque
Published: August 2004

This study examined how the testing procedure might affect performances on the water-level task and the verticality task in the course of development, comparing performances on a two-dimensional graphic version (drawings of jars and of a hillside) and on a three-dimensional graphic version (real jars and a physical model of a hill). Results showed that performance improved with age and that scores on the 3D version were better as a whole than on the 2D version. The verticality task was quite difficult for all children, whatever the version. When the verticality task is presented in a blindfolded condition, children performed better than in the normal condition. Major factors (both relevant and irrelevant) that affect performance during development are discussed.
Strategies of Source Attribution: Semantic Features and Trace Strength as Cues to the Origin of Memories
Authors: Echterhoff Gerald , Hussy Walter
Published: August 2004

Research has suggested that people may use different qualitative cues or one quantitative cue (trace strength, activation) to attribute memories to their source. In an experiment, the diagnosticity of a qualitative cue (semantic features) was manipulated between participants: Distinctness was high when items from source 1 and items from source 2 belonged to different semantic categories, while it was low when both sources contained items from both categories. Depending on the study-test interval (48 hr or 10 min), trace strength of test items was either low or high for all participants. Thus, the quantitative cue was always diagnostic. Participants primarily used semantic cues in source attributions of new items. Also, source identification performance profited from semantic dissimilarity, not from high trace strength. The findings indicate that qualitative cues may play a more prominent role than quantitative cues in source monitoring.
Was ist klinisch bedeutsam an klinisch bedeutsamer Veränderung?
Authors: Percevic Robert , Bauer Stephanie , Kordy Hans
Published: August 2004

Zusammenfassung. Theoretischer Hintergrund: Unter klinisch bedeutsamer Veränderung (KBV) wird eine reliable Verbesserung bei Erreichen eines Zielbereich verstanden. Da KBV zwar ein operationales aber kein statistisches Konzept darstellt, ist die Wahl des Zielbereiches aus statistischer Sicht arbiträr und verlangt eine inhaltliche Begründung. Fragestellung: Welche Bedeutung hat die Wahl des Zielbereiches für die Validität der KBV? Methode: Grundlage der Analysen bilden SCL-90-R (GSI) Daten einer repräsentativen Bevölkerungsstichprobe (N = 2.145) und einer Patientenstichprobe (N = 1.665). Untersucht werden die Zusammenhänge zwischen Zielbereich, KBV-Rate, Sensitivität und Spezifität sowie zwischen KBV und Suizidgedanken, Arbeitsunfähigkeit und Weiterbehandlung. Ergebnisse: Die vorgeschlagene Metdode führt zu einem Zielbereich mit einer Obergrenze zwischen 0,6 und 0,8 beim GSI der SCL-90-R, der am ehesten den Erwartungen bezüglich Fehlklassifikationsraten und Kriteriumsvalidität entspricht. Schlussfolgerungen: Der Zielbereich beeinflusst maßgeblich Fehlklassifikationsraten und Kriteriumsvalidität.
Mütterliche Einstellungen zur sprachtherapeutischen Behandlung ihrer Kinder
Authors: Ritterfeld Ute , Rindermann Heiner
Published: August 2004

Zusammenfassung. Theoretischer Hintergrund: Die Behandlung von Sprachentwicklungsstörungen erfordert neben psycholinguistischer Kindertherapie die Mitarbeit der Eltern. Hierfür sind elterliche Einstellungen zur Sprachtherapie relevant. Fragestellung: Untersuchung der Einstellungen von Müttern zur Sprachtherapie, Überprüfung des Zusammenhangs dieser Einstellungen zu externen Belastungsfaktoren sowie subjektiven Schuld- oder Überforderungsgefühlen und zur Partizipationsbereitschaft. Methode: Befragung von Müttern (N=116, standardisierte Fragebögen) sprachtherapeutisch behandelter Kinder, Auswertung mittels Korrelations- und Regressionsanalysen und Überprüfung eines theoretischen Modells mittels Strukturgleichungsverfahren. Ergebnisse: Mütter sind bereit, sich am sprachtherapeutischen Prozess ihrer Kinder zu beteiligen. Wenn aber objektive Lebensumstände die Ressourcen der Mütter einschränken oder wenn die Therapie als Belastung wahrgenommen wird, ist die Bereitschaft zur Verantwortungsabgabe erhöht und zur Therapieunterstützung eingeschränkt. Mütter schätzen Sprachdefizite ihrer Kinder nicht immer adäquat ein. Schlussfolgerung: Aufklärung der Eltern über Verfahren und Ziele der Sprachtherapie sind für deren Therapiewertschätzung und Partizipation wichtig. Es ist zu empfehlen, Müttern Sinn und Zweck einer spielerischen Intervention zu verdeutlichen.
Selbstöffnung beim Schreiben über belastende Lebensereignisse
Authors: Kröner-Herwig Birgit , Linkemann Annedore , Morris Lisette
Published: August 2004

Zusammenfassung. Theoretischer Hintergrund: Ausgangspunkt der beiden vorgestellten Studien ist die Forschung zu der Bedeutung von Selbstöffnung beim gefühlsbetonten Schreiben über belastende Ereignisse, die von Pennebaker und Mitarbeitern initiiert wurde. Nach Pennebaker belegen die Studien den langfristigen gesundheitsfördernden Effekt dieser kurzen und unaufwendigen Intervention. Methode: Die erste Studie versuchte im wesentlichen eine Replikation der Studie von Pennebaker und Beall (1986) mit der Erwartung, die von den Autoren beschriebenen Effekte bestätigen zu können. Neben den in der Originalstudie verwandten Erhebungsinstrumenten wurden verschiedene Essayvariablen extrahiert und eine Reihe von Persönlichkeitsmerkmalen erhoben, für die eine Moderatorfunktion bezüglich der Ergebnisvariablen angenommen wurde. Die zweite Studie variierte die Bedingung der Selbstöffnung, indem zusätzlich zur Ursprungsbedingung eine sogenannte “Coping“- bzw. “Helping“-Instruktion gegeben wurde, die über Aktivierung von Ressourcen deutlichere Wirkung im Sinne der Hypothesen zeigen sollte. Ergebnisse: In der ersten und zweiten Studie wurden keine langfristigen positiven Effekte auf die erhobenen Gesundheitsvariablen (z.B. Arztbesuche) gefunden. Die Essaymerkmale sowie die Persönlichkeitsmerkmale erklären fast keine Varianz in den Ergebnisvariablen. Es wurden Veränderungen in Parametern der Belastungsreaktion (z.B. Intrusion) gefunden. Diese waren besonders ausgeprägt bei der Aktivierung prosozialer Motivation (“Helping“-Bedingung). Schlussfolgerung: Das mehrmalige (aber kurzzeitige) gefühlsaktivierende Schreiben über belastende Ereignisse der Vergangenheit erzielt keine gesundheitlich positiven Konsequenzen. Es fördert aber eine bessere Belastungsverarbeitung.
Patientenzufriedenheit mit Psychopharmakotherapie
Authors: Scope Ambros , Baumann Urs
Published: August 2004

Zusammenfassung. Theoretischer Hintergrund: In den letzten Jahren gewann die Zufriedenheit von Patienten auf Grund gesundheitspolitischer und ökonomischer Gründe, aber auch aus klinischen und wissenschaftlichen Fragestellungen heraus an Bedeutung. Dabei werden multivariate Modelle propagiert. Fragestellung: In der vorliegenden Untersuchung wird der Zusammenhang der globalen Zufriedenheit mit der medikamentösen Behandlung mit unterschiedlichen Komponenten (Information, Mitgestaltung, Behandler/Patient-Beziehung, Wirkung der medikamentösen Behandlung) untersucht. In einem weiteren Schritt wird das Konzept auf die Zufriedenheit mit der stationären Behandlung erweitert. Schließlich werden zusätzlich Merkmale der Patienten zu einem Modell der Zufriedenheitsbildung verknüpft. Methode: 135 erwachsene stationäre psychiatrische Patienten wurden kurz vor Austritt ihres mindestens 14-tägigen Klinikaufenthalts zu Merkmalen der Patienten, der medikamentösen Behandlung, sowie zu unterschiedlichen Komponenten der Zufriedenheit befragt. Die Auswertung erfolgt mittels linearer Strukturgleichungsmodelle in Pfadanalysen. Ergebnisse: Die globale Zufriedenheit mit der medikamentösen Behandlung wird insbesondere durch die Aspekte Information und Wirkung der medikamentösen Behandlung beeinflusst. Bezogen auf die Zufriedenheit mit der stationären Behandlung erweist sich die Zufriedenheit mit der medikamentösen Behandlung bedeutsamer als die Zufriedenheit mit anderen Aspekten der stationären Behandlung. Weiters zeigt sich, daß Merkmale der Behandlung und Merkmale der Patienten ähnlich starke Zusammenhänge mit der Zufriedenheit der Patienten bezüglich medikamentöser Behandlung aufweisen. Schlussfolgerung: Anhand der Ergebnisse werden Vorschläge zur Steigerung der Zufriedenheit diskutiert.
Energetic particle observations in the vicinity of Jupiter: Cassini MIMI/LEMMS results
Authors: Krupp N. , Woch J. , Lagg A. , Livi S. , Mitchell D. G. , Krimigis S. M. , Dougherty M. K. , Hanlon P. G. , Armstrong T. P. , Espinosa S. A.
Published: August 2004

We report on energetic particle measurements from the Low Energy Magnetospheric Measurement System (LEMMS) on board the Cassini spacecraft during the Jupiter flyby (October 2000 to April 2001). Cassini passed Jupiter on its way to Saturn on the dusk flank of the magnetosphere and explored for the first time the dusk‐to‐midnight magnetosheath of the planet. The flyby period can be divided into three distinct regimes where energetic particle parameter changes are observed. The first period (October 2000 to 10 January 2001) covers the approach phase toward the planet, including bow shock crossings in and out of the magnetosheath as well as the closest approach. In this period, LEMMS responded on solar wind pressure pulses and recorded the passing of two interplanetary shocks. Hours before the first bow shock crossing, low‐energy particle intensity increases were observed, possibly with Jovian origin. Before the closest approach approach to the planet two inbound and one outbound bow shock crossings have been observed. The second period (9–10 January) is the period where Cassini briefly entered the magnetosphere twice at about 200 RJ. LEMMS data are only available during a large portion of the second encounter. Inside the magnetosphere the energetic electrons showed a bidirectional pitch angle distribution along the magnetic field, indicative of a closed magnetic field configuration predominantly in the north‐south direction. In addition, quasi‐periodic electron intensity variations with periods of ≈40 min were observed. The third period (January to April 2001) covers the distances between 205 and 800 RJ. The spacecraft was skimming along the bow shock boundary in the dusk‐to‐midnight sector. More than 44 inbound and outbound bow shock crossings have been observed. The most interesting magnetosheath encounter occurred between day 19 and day 28 at distances between 300 and 400 RJ. In that period, LEMMS observed strong intensification of MeV‐electron fluxes to values similar to those measured inside the magnetosphere as reported by Krupp et al. [2002]. Most of these increases in electrons were associated with sign changes in the north‐south component of the magnetic field. We interpret these observations in terms of magnetic dayside reconnection and particle leakage through the duskside magnetosheath.
Estimating the predictability of an oceanic time series using linear and nonlinear methods
Authors: Yuan G.‐C. , Lozier M. S. , Pratt L. J. , Jones C. K. R. T. , Helfrich K. R.
Published: August 2004

This study establishes a series of tests to examine the relative utility of nonlinear time series analysis for oceanic data. The performance of linear autoregressive models and nonlinear delay coordinate embedding methods are compared for three numerical and two observational data sets. The two observational data sets are (1) an hourly near‐bottom pressure time series from the South Atlantic Bight and (2) an hourly current‐meter time series from the Middle Atlantic Bight (MAB). The nonlinear methods give significantly better predictions than the linear methods when the underlying dynamics have low dimensionality. When the dimensionality is high, the utility of nonlinear methods is limited by the length and quality of the time series. On the application side we mainly focus on the MAB data set. We find that the slope velocities are much less predictable than shelf velocities. Predictability on the slope after several hours is no better than the statistical mean. On the other hand, significant predictability of shelf velocities can be obtained for up to at least 12 hours.
Sensitivity of Global Modeling Initiative model predictions of Antarctic ozone recovery to input meteorological fields
Authors: Considine David B. , Connell Peter S. , Bergmann Daniel J. , Rotman Douglas A. , Strahan Susan E.
Published: August 2004

We use the Global Modeling Initiative chemistry and transport model to simulate the evolution of stratospheric ozone between 1995 and 2030, using boundary conditions consistent with the recent World Meteorological Organization ozone assessment. We compare the Antarctic ozone recovery predictions of two simulations, one driven by an annually repeated year of meteorological data from a general circulation model (GCM), the other using a year of output from a data assimilation system (DAS), to examine the sensitivity of Antarctic ozone recovery predictions to the characteristic dynamical differences between GCM‐ and DAS‐generated meteorological data. Although the age of air in the Antarctic lower stratosphere differs by a factor of 2 between the simulations, we find little sensitivity of the 1995–2030 Antarctic ozone recovery between 350 and 650 K to the differing meteorological fields, particularly when the recovery is specified in mixing ratio units. Percent changes are smaller in the DAS‐driven simulation compared to the GCM‐driven simulation because of a surplus of Antarctic ozone in the DAS‐driven simulation which is not consistent with observations. The peak ozone change between 1995 and 2030 in both simulations is ∼20% lower than photochemical expectations, indicating that changes in ozone transport due to changing ozone gradients at 450 K between 1995 and 2030 constitute a small negative feedback. Total winter/spring ozone loss during the base year (1995) of both simulations and the rate of ozone loss during August and September is somewhat weaker than observed. This appears to be due to underestimates of Antarctic Cly at the 450‐K potential temperature level.
Nonlinearity in atmospheric response: A direct sensitivity analysis approach
Authors: Hakami Amir , Odman Mehmet T. , Russell Armistead G.
Published: August 2004

The decoupled direct method (DDM) is used for efficient and accurate calculation of the higher‐order sensitivity coefficients in a regional photochemical air quality model with detailed chemical mechanism (Statewide Air Pollution Research Center (SAPRC‐99)). High‐order DDM (HDDM) is an extension to a previous implementation of DDM in three‐dimensional air quality models (DDM‐3D) that directly calculates the higher‐order derivatives (with respect to one parameter, as well as cross derivatives) with similar computational efficiency as the first‐order implementation and is also modified for better accuracy. (H)DDM results show very good agreement with brute force (finite difference) sensitivity coefficients for the first‐ and second‐order derivatives, but the agreement deteriorates for higher‐order coefficients. The nature of the truncation errors and other inaccuracies in the brute force approximations are explored. The difference between the first‐order brute force and DDM derivatives is dominated (and largely explained) by the truncation errors as calculated from HDDM results. Taylor expansion is used for parametric scaling of the response with the use of sensitivity coefficients. Use of higher‐order coefficients can significantly improve the accuracy of such projections. Finally, higher‐order sensitivity coefficients of ozone with respect to NOx and volatile organic compound emissions (including cross derivatives) are used to create time‐ and location‐dependent ozone isopleths.
Modeling the effects of vegetation‐erosion coupling on landscape evolution
Authors: Collins D. B. G. , Bras R. L. , Tucker G. E.
Published: August 2004

From rainfall interception at the canopy to added soil cohesion within the root zone, plants play a significant role in directing local geomorphic dynamics, and vice versa. The consequences at the regional scale, however, are known in less quantitative terms. In light of this, the numerical Channel‐Hillslope Integrated Landscape Development model is equipped with coupled vegetation‐erosion dynamics, allowing for sensitivity analysis on the various aspects of vegetation behavior. The processes considered are plant growth, plant death, and the additional resistance imparted by plants against erosion. With each process is associated a single parameter, whose effects on the spatiotemporal nature of a 1 km2 basin is studied. Through their inhibition of erosion, plants steepened the topography and reduced drainage density, yet, in doing so, made erosive events more extreme. Plants more susceptible to erosion act to decouple neighboring cells and cause extensive and perennial network and channel adjustments.
Environmental magnetic record of paleoclimate change from the Eocene‐Oligocene stratotype section, Massignano, Italy
Authors: Jovane Luigi , Florindo Fabio , Dinarès‐Turell Jaume
Published: August 2004

A high‐resolution environmental magnetic study of the Massignano section, Italy (Global Stratotype Section and Point for the Eocene‐Oligocene boundary), has been performed to test whether a clear magnetic signature associated with climatic change is recognizable in this record. Our results reveal the existence of alternating intervals with high and low magnetic mineral concentrations similar to the pattern of rock magnetic property variations observed from an environmental magnetic study of the CIROS‐1 sediment core from Antarctica. These results suggest that an external forcing mechanism drove the sedimentary response to global climate change prior to the major Oi‐1 cooling event at the Eocene‐Oligocene boundary.
High‐resolution gravity survey: Investigation of subsurface structures at Poás volcano, Costa Rica
Authors: Fournier Nicolas , Rymer Hazel , Williams‐Jones Glyn , Brenes Jorge
Published: August 2004

Bouguer gravity surveys have long been used to investigate sub‐surface density contrasts. The main sources of error in previous surveys have been the determination of relative elevations of stations and the effect of topography (removed via the terrain correction). The availability of high precision Kinematic GPS data now facilitates generation of high‐resolution Digital Elevation Models that can help to improve the accuracy of relative elevation determination and the terrain correction. Here we describe a high‐resolution gravity survey at Poás volcano, Costa Rica. Our gravity modelling (i) identifies small pockets of magma at shallow depths which relate to successive magma intrusion through time and (ii) shows that the persistent degassing in the eastern part of the crater is related to local deformation at the top of the volcano and changes in the fracture network, rather than to the presence of a shallow magma intrusion.
Stability of direct GPS estimates of ocean tide loading
Authors: Allinson C. R. , Clarke P. J. , Edwards S. J. , King M. A. , Baker T. F. , Cruddace P. R.
Published: August 2004

We observe ocean tide loading (OTL) at diurnal and semi‐diurnal periods by directly estimating fixed‐period harmonic motions within individual daily GPS analyses. Stacking of multiple solutions allows us to isolate the principal near‐diurnal and near‐semi‐diurnal OTL components. Using data from UK sites where predicted OTL for the M2component varies from 3–46 mm in amplitude, we show that our estimates are stable for the principal OTL components when data from at least 90 days are stacked. Our final observations are compared to model predictions (using the FES95.2, FES99, GOT00.2, TPXO.2, TPXO.6, NAO.99b and CSR3 models) and are in agreement with OTL predicted by FES99, but differ significantly at some locations from those predicted by the CSR3 and TPXO.2 tidal models.
Accurate cross sections for excitation of resonance transitions in atomic oxygen
Authors: Tayal S. S.
Published: August 2004

Electron collision excitation cross sections for the resonance 2p43P–2p33s3So, 2p43P–2p33d3Do, 2p43P–2p33s3Do, 2p43P–2p33s3Po, and 2p43P–2s2p53Po transitions have been calculated by using the R matrix with a pseudostates approach for incident electron energies from near threshold to 100 eV. The excitation of these transitions gives rise to strong atomic oxygen emission features at 1304, 1027, 989, 878, and 792 Å in the spectra of several planetary atmospheres. We included 22 spectroscopic bound and autoionizing states and 30 pseudostates in the close‐coupling expansion. The target wave functions are chosen to properly account for the important correlation and relaxation effects. The effect of coupling to the continuum is included through the use of pseudostates. The contribution of the ionization continuum is significant for resonance transitions. Measured absolute direct excitation cross sections of O I are reported by experimental groups from the Jet Propulsion Laboratory and Johns Hopkins University. Good agreement is noted for the 2p43P–2p33s3So transition (λ1304 Å) with measured cross sections from both groups that agree well with each other. There is disagreement between experiments for other transitions. Our results support the measured cross sections from the Johns Hopkins University for the 2p43P–2p33d3Do and 2p43P–2p33s3Do transitions, while for the 2p43P–2p33s3Po transition the agreement is switched to the measured cross sections from the Jet Propulsion Laboratory.
Evidence of fluid‐filled upper crust from observations of postseismic deformation due to the 1992 Mw7.3 Landers earthquake
Authors: Fialko Yuri
Published: August 2004

Postseismic deformation due to the 1992 Mw7.3 Landers, southern California, earthquake is investigated using the entire catalog of the ERS synthetic aperture radar (SAR) data, and GPS measurements made between 1992 and 1999. The stacked interferometric SAR (InSAR) data spanning the time period of 7 years between the Landers and the Hector Mine earthquakes reveal a transient postseismic deformation with a characteristic decay time of several years. The horizontal displacements measured with GPS exhibit somewhat smaller decay times of 1–2 years. I use a slip model of the Landers earthquake that fits all available geodetic data [Fialko, 2004] to calculate and compare permanent postseismic displacements due to viscoelastic and poroelastic relaxation. Viscoelastic models assuming weak mantle or lower crust do not agree with the InSAR data in the limit of complete relaxation, implying large (>10 years) relaxation times, essentially nonlinear rheology, or an appreciable yield strength of the lower lithosphere. A combination of poroelastic relaxation above the brittle‐ductile transition and localized shear deformation on and below the Landers rupture is able to explain most of the available geodetic data. The InSAR data suggest that pore fluids and interconnected pore space are ubiquitously present throughout the seismogenic layer up to depth of 15 km or greater. The effective hydraulic diffusivity of the upper crust inferred from the kinetics of surface deformation is of the order of 0.1–1 m2/s, consistent with the laboratory, field, and deep borehole measurements. The post‐Landers geodetic data suggest that discrete narrow fault zones extend into the lower crust and perhaps the uppermost mantle, thus lending support to a “block tectonics” model of the Eastern California Shear Zone.
Sediment trapping, turbidity maxima, and bathymetric stability in macrotidal estuaries
Authors: Prandle D.
Published: August 2004

This paper examines how fine marine sediments are trapped in macrotidal estuaries and what processes coexist to maintain bathymetric stability. An analytical emulator is constructed integrating explicit formulations for tidal and residual current structures together with sediment erosion, suspension, and deposition. The emulator estimates suspended concentrations and net sediment fluxes and indicates the nature of their functional dependencies and corresponding sensitivities to tidal elevation amplitude (or tidal current ), channel depth D, bed friction coefficient f, sediment size (specifically, settling velocity Ws), and river flow velocity UR. Associated scaling analyses reveal the relative impacts of terms representing tidal nonlinearities, gravitational circulation, and “delayed” settling. Using the emulator to determine conditions consistent with zero net flux of sediments or bathymetric stability, we deduce Ws ≈ f. Overall, finer sediments are imported and coarser ones are exported, with more imports (extending to a coarser fraction) on spring tides than on neaps. The emulator indicates that the spring‐neap shifting of this coarse‐fine boundary corresponds to particle diameters between 30 and 50 μm. This constitutes selective sorting, maintaining a widely distributed source of continuously resuspended material in a size range commonly observed. By illustrating the acute sensitivity of sediment fluxes to the bed friction coefficient, we anticipate feedback adjustments between suspended and surficial sediments. Factors governing the generation, location, and characteristics of turbidity maxima are indicated, including dependence on /D. A direct link is shown between parameters that control sediment flux at a specific cross section and net upstream tidal energy dissipation.
Ozone column retrieval from solar UV irradiance measurements at ground level: Sensitivity tests and uncertainty estimation
Authors: Houët Mickaël , Brogniez Colette
Published: August 2004

Since the discovery of the stratospheric ozone depletion in the 1980s [World Meteorological Organization/United Nations Environment Programme (WMO/UNEP), 1994; Solomon, 1999; Staehelin et al., 2001], the interest of its measurement has substantially increased. Indeed, this gas highly absorbs the dangerous UV radiation and preserves the biosphere. Long series of measurements of total ozone column and of solar UV radiation are needed to define climatologies of both UV and ozone and to study the impact of the ozone depletion at the Earth surface. Total ozone column is determined at Villeneuve d'Ascq, France, by a differential absorption method, using global spectral UV measurements performed with a Jobin Yvon spectroradiometer by the Laboratoire d'Optique Atmospherique. This method is based on the comparison between two irradiance ratios, one simulated beforehand and stored in a lookup table (LUT) and one calculated from the measured spectrum [Stamnes et al., 1991]. This paper presents the method used to improve the choice of the different irradiances used to calculate the ratios and presents the five irradiance ratios that are finally kept. Some sensitivity tests are performed in order to find the validity range of a LUT and the number of LUTs needed. These tests reveal that the aerosol Ångström coefficient, the aerosol optical depth, and the atmospheric vertical profiles may induce errors in the ozone retrieval. That makes it necessary to calculate 21 LUTs and to select one of them depending on the season and on the aerosol properties. Then an estimation of the uncertainty of the method is performed, enabling us to conclude that the method leads to approximately 3% relative uncertainty. The results for the clear days of the last 3 years at Villeneuve d'Ascq are presented, as well as a comparison with Total Ozone Mapping Spectrometer data. In most of the cases, both values agree to within 5%, but some cases present larger relative differences.
Spatial relationships between patterned ground and ground ice detected by the Neutron Spectrometer on Mars
Authors: Mangold N. , Maurice S. , Feldman W. C. , Costard F. , Forget F.
Published: August 2004

Patterned grounds, like polygonal features, are the signature of climatic effects in periglacial regions on Earth. Identifying similar features on Mars is important for an understanding of the past Martian climate. In this study we mapped fresh patterned landforms from the systematic analysis of Mars Orbiter Camera high‐resolution images. We show that most of them are distributed at latitudes poleward of ±55°, making a climatic control likely. This distribution correlates to the distribution of ground ice detected by the Neutron Spectrometer aboard Mars Odyssey. This correlation is likely the consequence of the Neutron Spectrometer detecting ice no deeper than about 1 m. Patterned ground formation requires ice in this range of depth because these features are triggered by the propagation of a thermal wave that is driven by seasonal or diurnal changes in insolation, which affect the temperature in the uppermost ground layers. Sublimation seems to play a role in the shaping of many of the small patterns observed at latitudes between 55° and 70°. No widespread polygonal features are correlated to the equatorial regions where hydrogen is detected by the Neutron Spectrometer.
Involvement of the nucleolus in plant virus systemic infection
Authors: Kim S.H. , Ryabov E.V. , Brown J.W.S. , Taliansky M.
Published: August 2004

The nucleolus is a prominent subnuclear domain and is classically regarded as the site of transcription of rRNA, processing of the precursor rRNAs and biogenesis of pre-ribosomal particles. In addition to these traditionally recognized activities, the nucleolus also participates in many other aspects of cell function. The umbravirus-encoded ORF3 protein is a multifunctional RNA-binding protein involved in long-distance RNA movement, and protection of viral RNA from RNase attack, including possibly small interfering RNA-guided RNA silencing. In addition to its presence in cytoplasmic ribonucleoprotein particles containing viral RNA, the umbraviral ORF3 protein accumulates in nuclei, preferentially targeting nucleoli. The ORF3 protein domains involved in the localization of the protein to the nucleolus were identified. Functional analysis of the mutants revealed the correlation between the ORF3 protein nucleolar localization and its ability to form the cytoplasmic ribonucleoprotein particles and transport viral RNA long distances via the phloem. Possible mechanisms of the nucleolar involvement in systemic virus infection are discussed.
A plethora of plant serine/arginine-rich proteins: redundancy or evolution of novel gene functions?
Authors: Kalyna M. , Barta A.
Published: August 2004

Precursor-mRNA (pre-mRNA) processing is an important step in gene expression and its regulation leads to the expansion of the gene product repertoire. SR (serine-arginine)-rich proteins are key players in intron recognition and spliceosome assembly and significantly contribute to the alternative splicing process. Due to several duplication events, at least 19 SR proteins are present in the Arabidopsis genome, which is almost twice as many as in humans. They fall into seven different subfamilies, three of them homologous with metazoan splicing factors, whereas the other four seem to be specific for plants. The current results show that most of the duplicated genes have different spatiotemporal expression patterns indicating functional diversification. Interestingly, most of the SR protein genes are alternatively spliced and in some cases this process was shown to be under developmental and/or environmental control. This might greatly influence gene expression of target genes as also exemplified by ectopic expression studies of particular SR proteins.
Post-transcriptional steps involved in the assembly of photosystem I in Chlamydomonas
Authors: Rochaix J.-D. , Perron K. , Dauvillée D. , Laroche F. , Takahashi Y. , Goldschmidt-Clermont M.
Published: August 2004

Assembly of the PSI (photosystem I) complex in eukaryotic photosynthetic organisms depends on the concerted interactions of the nuclear and chloroplast genetic systems. We have identified several nucleus-encoded factors of Chlamydomonas reinhardtii that are specifically required for the synthesis of the two large chloroplast-encoded reaction-centre polypeptides, PsaA and PsaB, of photosystem I and that function at plastid post-transcriptional steps. Raa1, Raa2 and Raa3 are required for the splicing of the three discontinuous psaA precursor transcripts; they are part of large RNA–protein complexes that are reminiscent of spliceosomal particles. Tab1 and Tab2 are involved in the initiation of translation of the psaB mRNA and are localized in the membrane and stromal phases of the chloroplast, where they are associated with high-molecular-mass complexes. Moreover, two chloroplast-encoded proteins, Ycf3 and Ycf4, are required for the primary steps of assembling the photosystem I subunits into a functional complex.
Genetics of the DST-mediated mRNA decay pathway using a transgene-based selection
Authors: Lidder P. , Johnson M.A. , Sullivan M.L. , Thompson D.M. , Pérez-Amador M.A. , Howard C.J , Green P.J.
Published: August 2004

mRNA sequences that control abundance, localization and translation initiation have been identified, yet the factors that recognize these sequences are largely unknown. In this report, a transgene-based strategy designed to isolate mutants of Arabidopsis thaliana that fail to recognize these sequences is described. In this strategy, a selectable gene and a screenable marker gene are put under the control of the sequence element being analysed and mutants are selected with altered abundance of the corresponding marker RNAs. The selection of mutants deficient in recognition of the DST (downstream) mRNA degradation signal is used as a test-case to illustrate some of the technical aspects that have facilitated success. Using this strategy, we report the isolation of a new mutant, dst3, deficient in the DST-mediated mRNA decay pathway. The targeted genetic strategy described circumvents certain technical limitations of biochemical approaches. Hence, it provides a means to investigate a variety of other mechanisms responsible for post-transcriptional regulation.
Plant growth: the translational connection
Authors: Robaglia C. , Menand B. , Lei Y. , Sormani R. , Nicolaï M. , Gery C. , Teoulé E. , Deprost D. , Meyer C.
Published: August 2004

The TOR (target of rapamycin) pathway is a phylogenetically conserved transduction system in eukaryotes linking the energy status of the cell to the protein synthesis apparatus and to cell growth. The TOR protein is specifically inhibited by a rapamycin–FKBP12 complex (where FKBP stands for FK506-binding protein) in yeast and animal cells. Whereas plants appear insensitive to rapamycin, Arabidopsis thaliana harbours a single TOR gene, which is essential for embryonic development. It was found that the product of this gene was capable of binding to rapamycin and yeast FKBP12. In-frame fusion with a GUS reporter gene shows that the TOR protein is produced essentially in proliferating zones, whereas the TOR mRNA can be detected in all organs suggesting a translational regulation of TOR. Phenotypic analysis of Arabidopsis TOR mutants indicates that the plant TOR pathway fulfils the same role in controlling cell growth as its other eukaryotic counterparts.
A key factor of translation reinitiation, ribosomal protein L24, is involved in gynoecium development in Arabidopsis
Authors: Nishimura T. , Wada T. , Okada K.
Published: August 2004

In polycistronic genes, uORFs (upstream open reading frames) within the 5′-transcript leader sequence of major ORFs may regulate the translation of these major ORFs. In this case, ribosome reinitiates translation at a start codon of downstream ORF after translation termination of uORF. The plant RPL24 (ribosomal protein L24) is a key factor for translation reinitiation of downstream ORFs on the polycistronic cauliflower mosaic virus 35S RNA transcription unit. In the RPL24-deficient mutant of Arabidopsis, short valve (stv), the basal region of the ovary is shortened, whereas the gynophore appears elongated. This phenotype is never seen in known mutants of other ribosomal protein genes, suggesting that RPL24 has a specific role in gynoecium development. Similar phenotypes were observed in the ett (ettin) and mp (monopteros) mutants. Both ETT and MP genes possess uORFs. We examined the hypothesis that these uORFs regulate their downstream major ORFs by a transient expression assay in Arabidopsis mesophyll protoplasts. Our results supported the idea, suggesting that the structural defects of the gynoecium in stv mutants were caused by decreased efficiency of translation reinitiation of ETT and/or MP.
Choice of a start codon in a single transcript determines DNA ligase 1 isoform production and intracellular targeting in Arabidopsis thaliana
Authors: Sunderland P.A. , West C.E. , Waterworth W.M. , Bray C.M.
Published: August 2004

DNA ligase 1 (AtLIG1) is the only essential DNA ligase activity in Arabidopsis and is implicated in the important processes of DNA replication, repair and recombination and in transgene insertion during Agrobacterium-mediated plant transformations. The mitochondrial and nuclear forms of DNA ligase 1 in Arabidopsis are translated from a single mRNA species through the control of translation initiation from either the first (M1) or second (M2) in-frame AUG codons respectively. Translation from a third in-frame AUG codon (M3) occurs on transcripts in which M1 and M2 are mutagenized to stop codons. Wild-type AtLIG1–GFP constructs (where GFP stands for green fluorescent protein) can be targeted in planta to both the nucleus and mitochondria. AtLIG1–GFP translation from M1 specifically targets the fusion protein only to mitochondria in planta, whereas translation from M2 or M3 targets the fusion protein only to the nucleus. Interestingly, the AtLIG1–GFP fusion protein in which translation is initiated from M1 contains both an N-terminal mtPS (mitochondrial targeting presequence) and a nuclear localization signal; nonetheless, this protein is only targeted to the mitochondria. This result raises intriguing questions on the translational control mechanisms that regulate how the protein products of a single transcript are targeted to more than one cellular compartment.
Peptides complexed with the protein HSP70 generate efficient human cytolytic T-lymphocyte responses
Authors: Javid B. , MacAry P.A. , Oehlmann W. , Singh M. , Lehner P.J.
Published: August 2004

Microbial HSPs (heat-shock proteins) are implicated in the induction of the innate and adaptive arms of the immune response. We set out to determine whether peptides complexed with HSP70 generate efficient CTL (cytolytic T-lymphocyte) responses. Human dendritic cells pulsed with peptide-loaded microbial HSP70 complexes generate potent antigen-specific CTL responses. Using fluorescence anisotropy, we have calculated the peptide-binding affinity of mycobacterial HSP70 (KD=14 μM) and show that 120 pM HSP70-bound peptide is sufficient to generate a peptide-specific CTL response that is four orders of magnitude more efficient than the peptide alone. Through the generation of mycobacterial HSP70 truncations, we find that the minimal 136 amino acid, mycobacterial HSP70 peptide-binding domain is sufficient to generate CTL responses. The design of an HSP70 mutant, in which the peptide-binding site of HSP70 is filled with a bulky hydrophobic residue, leads to a large decrease in the peptide-binding affinity. This mutant HSP70 retains stimulatory capacity but is unable to generate CTL and has separated antigen delivery from immunostimulation of dendritic cells.
BCG (Bacille Calmette–Guérin) HspCs (heat-shock protein–peptide complexes) induce T-helper 1 responses and protect against live challenge in a murine aerosol challenge model of pulmonary tuberculosis
Authors: Colaco C.A.L.S. , Bailey C.R. , Keeble J. , Walker K.B.
Published: August 2004

The need for an effective TB (tuberculosis) vaccine remains acute, with tuberculosis still one of the major killers worldwide and 3 million new infections annually. We report here on the immune responses elicited by HspCs (heat-shock protein–peptide complexes) isolated from BCG (Bacille Calmette–Guérin) vaccine. These HspCs elicit both the appropriate cellular and protective immune responses required to merit their further development as TB vaccine candidates.
Functional domains of HSP70 stimulate generation of cytokines and chemokines, maturation of dendritic cells and adjuvanticity
Authors: Lehner T. , Wang Y. , Whittall T. , McGowan E. , Kelly C.G. , Singh M.
Published: August 2004

Microbial HSP70 (heat-shock protein 70) consists of three functionally distinct domains: an N-terminal 44 kDa ATPase portion (amino acids 1–358), followed by an 18 kDa peptide-binding domain (amino acids 359–494) and a C-terminal 10 kDa fragment (amino acids 495–609). Immunological functions of these three different domains in stimulating monocytes and dendritic cells have not been fully defined. However, the C-terminal portion (amino acids 359–610) stimulates the production of CC chemokines, IL-12 (interleukin-12), TNFα(tumour necrosis factor α), NO and maturation of dendritic cells and also functions as an adjuvant in the induction of immune responses. In contrast, the ATPase domain of microbial HSP70 mostly lacks these functions. Since the receptor for HSP70 is CD40, which with its CD40 ligand constitutes a major co-stimulatory pathway in the interaction between antigen-presenting cells and T-cells, HSP70 may function as an alternative ligand to CD40L. HSP70–CD40 interaction has been demonstrated in non-human primates to play a role in HIV infection, in protection against Mycobacterium tuberculosis and in conversion of tolerance to immunity.
Scavenger receptors and heat-shock protein-mediated antigen cross-presentation
Authors: Delneste Y.
Published: August 2004

Heat-shock proteins (HSPs) induce protective cytotoxic immune responses against tumour antigens. This property is related to their ability to bind to and to be internalized by DC (dendritic cells) before gaining access to the MHC class I processing pathway, a process called antigen cross-presentation. This process requires internalization of the antigen by DC via endocytic receptors. Owing to their particular immune properties, several studies were focused on the identification of HSP-binding elements on DC. We and others have reported that scavenger receptors are the main HSP-binding structures on human DC and have identified LOX-1 as one of these molecules. The binding of human Hsp70 to DC and the in vitro Hsp70-mediated antigen cross-presentation are inhibited by an anti-LOX-1 monoclonal antibody. In vivo, targeting LOX-1 with a tumour antigen using an anti-LOX-1 monoclonal antibody induces antitumour immunity. Thus scavenger receptors are certainly new promising targets for cancer immunotherapy.
Neuronal DnaJ proteins HSJ1a and HSJ1b: a role in linking the Hsp70 chaperone machine to the ubiquitin–proteasome system?
Authors: Chapple J.P. , Spuy J. van der , Poopalasundaram S. , Cheetham M.E.
Published: August 2004

The heat-shock protein 70 chaperone machine is functionally connected to the ubiquitin–proteasome system by the co-chaperone CHIP. In this article, we discuss evidence that the neuronal DnaJ proteins HSJ1a and HSJ1b may represent a further link between the cellular protein folding and degradation machineries. We have demonstrated that HSJ1 proteins contain putative ubiquitin interaction motifs and can modulate the cellular processing of rhodopsin, a protein that is targeted for degradation by the proteasome when it is misfolded.