bluuebunny/crossref_metadata_2025 huggingface dataset:
The Legal System, the Courts and Law Reporting in Hong Kong
Authors: Pache Charlotte
Published: June 2007

This article by Charlotte Pache sets out the background of, and framework for, the legal system in Hong Kong. It outlines the structure of the courts and the legal profession, and details the practice for obtaining transcripts and judgments. It also provides a survey of law reporting and online resources for further information on case law and statute.
Die Validität von Schulnoten zur Vorhersage des Studienerfolgs - eine Metaanalyse 1Dieser Beitrag entstand im Kontext des Projekts “Eignungsdiagnostische Auswahl von Studierenden”, das im Rahmen des Aktionsprogramms “StudierendenAuswahl” des Stifterverbands für die Deutsche Wissenschaft und der Landesstiftung Baden-Württemberg durchgeführt wird.
Authors: Trapmann Sabrina , Hell Benedikt , Weigand Sonja , Schuler Heinz
Published: June 2007

Zusammenfassung. Schulabschlussnoten sind trotz erweiterter Möglichkeiten der Universitäten und Kritik an der Hinlänglichkeit zur Vorhersage des Studienerfolgs nach wie vor das häufigste Einzelkriterium, das zur Auswahl von Studierenden in Deutschland herangezogen wird. Die vorliegende Metaanalyse integriert die seit 1980 publizierten europäischen Studien zum Zusammenhang von einzelnen und durchschnittlichen Schulnoten einerseits und dem Studienerfolg andererseits (insgesamt 83 Koeffizienten). Es ergeben sich mittlere korrigierte Validitätskoeffizienten in Höhe von .26 bis .53 für das Studienerfolgskriterium Studiennoten. Die höchste Validität weisen deutsche Schuldurchschnittsnoten auf (ρ = .53, korrigiert für die Reliabilität der Studiennoten und die Varianzeinschränkung durch Selektion). Moderatoranalysen zeigen signifikante Einflüsse des Landes, des Studienfachs, der Zeitspanne zwischen Schul- und Studienleistung und des Studienabschnitts der Studienleistung. Die für Schulnoten berechneten Validitätskoeffizienten sind generalisierbar positiv und von Null verschieden.
Leseverständnis, Familiensprache und Freizeitsprache
Authors: Tiedemann Joachim , Billmann-Mahecha Elfriede
Published: June 2007

Zusammenfassung. Ziel der Studie ist es, sprachliche Bedingungen der Lesekompetenz (Leseverständnis) im Grundschulalter auf der Basis individueller Voraussetzungen und des schulischen Lernkontextes zu eruieren. Im Rahmen der Hannoverschen Grundschulstudie wurden an 620 Schülerinnen und Schülern vierter Klassen mehrere Leistungstest- und Fragebogendaten erhoben. Mit den Lehrkräften wurden ausführliche themenzentrierte Interviews geführt. Die Auswertung erfolgte mehrebenenanalytisch. Kinder mit Migrationshintergrund weisen eine deutlich verminderte Leseverständnisleistung auf. Neben der Umgangssprache in der Familie klärt die in der Freizeit gesprochene Sprache auch bei Kontrolle der nicht-verbalen Intelligenz und weiterer individueller Voraussetzungen substanzielle Anteile an Leseverständnisvarianz auf. Ein zusätzlicher Effekt dieser Faktoren auf Klassenebene konnte nicht ermittelt werden. Die Ergebnisse verweisen auf die Bedeutung der Frequenz des Gebrauchs der Verkehrssprache für die Lesekompetenz.
Förderung von Fertigkeiten zur Überarbeitung narrativer Texte bei Schülern der 6. Klasse
Authors: Glaser Cornelia , Brunstein Joachim C.
Published: June 2007

Zusammenfassung. In einer Stichprobe von 42 Schülern der 6. Klasse (N = 42) untersuchten wir die Effektivität eines Schreibtrainings, bei dem Strategien zur Revision narrativer Texte mit selbstregulatorischen Prozeduren kombiniert wurden. Schüler, die das Selbstregulatorische Revisionstraining (SRT) durchliefen, wurden mit (a) Schülern, denen die gleichen Strategien ohne Selbstregulation vermittelt wurden, und (b) Schülern, die herkömmlichen Aufsatzunterricht erhielten, verglichen. Im Zeitraum von 5 Wochen (1 Doppelstunde pro Woche) wurde in beiden Trainingsgruppen der Einsatz von Revisionsstrategien in Kleingruppen eingeübt. Das selbstregulatorische Training umfasste zusätzlich Übungen zur Zielsetzung, Strategieüberwachung und Selbstbewertung. Nach dem Training übertrafen SRT-Schüler beide Vergleichsgruppen bei Revisionsaufgaben. Bei Posttest- und Follow-up-Messungen erbrachten SRT-Schüler zudem überlegene Schreibleistungen sowohl in den Endfassungen (nach der Revision) als auch in den Rohfassungen (vor der Revision) ihrer Aufsätze.
Entwicklung der Rechtschreibleistung vom frühen Schul- bis zum frühen Erwachsenenalter
Authors: Schneider Wolfgang , Stefanek Jan
Published: June 2007

Zusammenfassung. Es werden Befunde der Münchner Längsschnittstudie zur Genese individueller Kompetenzen (LOGIK) vorgestellt, die die Rechtschreibentwicklung vom späten Kindesalter bis zum frühen Erwachsenenalter thematisieren. Die bereits für die Grundschulphase der Studie festgestellte hohe Zeitstabilität individueller Unterschiede im Rechtschreiben wird auch für die spätere Phase bestätigt. Frühe Vorteile der weiblichen Teilnehmer und der Probanden mit höherem Bildungsniveau setzten sich ebenfalls fort. Vom Jugendalter bis zum frühen Erwachsenenalter waren keine nennenswerten Leistungszuwächse erkennbar. Insgesamt deuten die Befunde für die Jugend- und Erwachsenenphase darauf hin, dass sich das durchschnittliche Rechtschreibniveau im Verlauf der letzten vier Jahrzehnte erheblich verschlechtert hat.
SIDAM: Alters- und bildungsspezifische Normen des kognitiven Leistungsteiles nach der neuen CASMIN-Bildungsklassifikation
Authors: Luck Tobias , Zaudig Michael , Wiese Birgitt , Riedel-Heller Steffi G.
Published: June 2007

Zusammenfassung: Mit dem SIDAM (Strukturiertes Interview für die Diagnose einer Demenz vom Alzheimer Typ, der Multiinfarkt- Demenz und Demenzen anderer Ätiologie nach DSM-III-R, DSM-IV und ICD-10) liegt ein standardisiertes Interview vor, welches Screening und Diagnose von Demenzen und leichten kognitiven Beeinträchtigungen ermöglicht. Alters- und bildungsspezifische Normen für den kognitiven Leistungsteil sind dabei unerlässlich, ihrerseits jedoch stark von der zugrunde liegenden Bildungsklassifikation abhängig. In der vorliegenden Arbeit werden bevölkerungsrepräsentative alters- und bildungsspezifische Normen des kognitiven SIDAM-Leistungsteiles auf der Grundlage einer aktuellen, nachvollziehbaren und international anerkannten Bildungsklassifikation (newCASMIN; Brauns & Steinmann, 1999 ) vorgelegt. Für die Trennung dementer von nichtdementen Personen werden Cut-off-Werte des SIDAM-Gesamtscores vorgeschlagen. Ermittelte statistische Kennwerte der einzelnen SIDAM-Subskalen ermöglichen zudem die Diagnose leichter kognitiver Beeinträchtigungen nach neuen Konsensuskriterien ( Winblad et al., 2004 ). Diese Veröffentlichung wurde im Rahmen des Kompetenznetzes Demenzen erstellt und vom Bundesministerium für Bildung und Forschung (BMBF) gefördert (Förderkennzeichen: O1 GI 0420).
Therapie von Verhaltensstörungen bei Menschen mit Demenz
Authors: Stoppe Gabriela , Maeck Lienhard
Published: June 2007

Zusammenfassung: Verhaltensstörungen sind vielgestaltig und häufig bei Demenzen. Ihr Auftreten und Ausmaß sind ein Hauptrisikofaktor für die Heimeinweisung. Mit zunehmender Demenzschwere wird ein Zusammenhang zu Umgebungsfaktoren immer deutlicher. Angehörigeninterventionen beeinflussen auch das Verhalten der Demenzkranken. Die Behandlung erfordert zunächst eine sorgfältige Analyse auslösender und verstärkender Faktoren. Bestehen Sie fort, so sollte ein Zielsymptom definiert werden und im Behandlungsverlauf dokumentiert werden. Unwirksame Therapien sollten nicht fortgesetzt werden. Pharmakologisch sind Antidementiva als Basistherapie zu prüfen. Im Übrigen haben nicht-anticholinerge Substanzen und atypische Neuroleptika (v. a. Risperidon, Aripiprazol, Olanzapin) eine begrenzte Wirksamkeit. Präparate mit wenig Interaktionen und kurzer Halbwertszeit sind zu bevorzugen. Seitens der nichtpharmakologischen Maßnahmen unterscheidet man Übungs- von sinnesorientierten Verfahren, sowie Validation, Musiktherapie und die Umgebungsgestaltung, die jedoch bis heute schlecht untersucht sind.
Classification Accuracy of Neural Networks vs. Discriminant Analysis, Logistic Regression, and Classification and Regression Trees
Authors: Finch Holmes , Schneider Mercedes K.
Published: June 2007

Abstract. This paper compares the predictive accuracy of three commonly used parametric methods for group classification, linear discriminant analysis, quadratic discriminant analysis, and logistic regression, with two less common approaches, neural networks and classification and regression trees. The simulation study examined the impact of such factors as inequality of covariance matrices, distribution of predictors, and group size ratio (among others) on the performance of each method. Results indicate that quadratic discriminant analysis always performs as well as the other methods while neural networks behave very similarly to linear discriminant analysis and logistic regression.
Consistency and Efficiency of Ordinary Least Squares, Maximum Likelihood, and Three Type II Linear Regression Models
Authors: Maroco João
Published: June 2007

Abstract. Type I linear regression models, which allow for measurement errors only in the criterion variable, are frequently used in modeling research in psychology and the social sciences. Although there are frequently measurement errors and large natural variation both in the criterion and predictor variables, type II regression methods that account for these errors are seldom used in these fields of study. The consistency and efficiency of three type II regression methods (reduced major axis, Kendall's robust line-fit and Bartlett's three-group) were evaluated in comparison to ordinary least squares (OLS) and the maximum likelihood with known variance ratio used frequently in biometrics and econometrics. When predictors are measured with error, OLS slope estimates are biased toward zero, and the same bias was observed with both Kendall's and Bartlett's methods. Reduced major axis produced consistent estimates even for small sample sizes, whenever the measurement errors in X are similar in magnitude to measurement errors in Y, but there was a consistent bias when the measurement error in X was smaller/greater than in Y. Maximum likelihood estimates behaved erroneously for small sample sizes, but for larger sample sizes they converged to the expected values.
Quantitative bedrock geology of the continents and large‐scale drainage regions
Authors: Peucker‐Ehrenbrink Bernhard , Miller Mark W.
Published: June 2007

We quantitatively analyze the area‐age distribution of sedimentary, extrusive volcanic, and endogenous (plutonic and/or metamorphic) bedrock on the basis of data from the most recent digital Geological Map of the World at a scale of 1:25,000,000. The spatial resolution of the digital bedrock data averages 13,905 km2 per polygon. Comparison of certain regions of the world, previously analyzed at higher spatial resolution, with the low‐resolution world data reveals general consistency in the areal exposure of major rock types as well as a minor systematic bias toward older average bedrock ages in the global data set. Application of the global bedrock data to 19 large‐scale drainage regions and three large, internally drained regions reveals considerable regional variability of Earth's bedrock geology that is consistent with the dominant geotectonic setting of the respective drainage region.
Comparison of polar motion excitation series derived from GRACE and from analyses of geophysical fluids
Authors: Nastula J. , Ponte R. M. , Salstein D. A.
Published: June 2007

Three sets of degree‐2, order‐1 harmonics of the gravity field, derived from the Gravity Recovery and Climate Experiment (GRACE) data processed at the Center for Space Research (CSR), Jet Propulsion Laboratory (JPL) and GeoforschungsZentrum (GFZ), are used to compute polar motion excitation functionsχ1andχ2. The GFZ and JPL excitations and the CSRχ2excitation compare generally well with geodetically observed excitation after removal of effects of oceanic currents and atmospheric winds. The agreement considerably exceeds that from previous GRACE data releases. For the JPL series, levels of correlation with the geodetic observations and the variance explained are comparable to, but still lower than, those obtained independently from available models and analyses of the atmosphere, ocean, and land hydrology. Improvements in data quality of gravity missions are still needed to deliver even tighter constraints on mass‐related excitation of polar motion.
Urban background aerosols: Negative correlations of particle modes and fragmentation mechanism
Authors: Gramotnev G. , Madl P. , Gramotnev D. K. , Burchill M. J.
Published: June 2007

We demonstrate new powerful methods of statistical analysis of atmospheric aerosols on the example of urban background aerosol in the Brisbane area, Australia. It is shown that even in the absence of notable features on the size distribution, it is still possible to identify distinct particles modes and analyze their mutual interactions and transformations. The obtained unique anti‐symmetric correlation patterns between particle modes may serve as fingerprints of particular evolutionary processes in the background aerosols. The obtained results suggest that thermal fragmentation of nano‐particles may be one of the major physical mechanisms shaping urban background aerosols. In particular, based on the fragmentation theorem, we demonstrate possible existence of substantially different time scales for fragmentation of atmospheric aerosols. The proposed approaches and obtained results may also be important for the analysis of different types of atmospheric aerosols on local, regional and global scales.
Electron microdiffusion in the Saturnian radiation belts: Cassini MIMI/LEMMS observations of energetic electron absorption by the icy moons
Authors: Roussos E. , Jones G. H. , Krupp N. , Paranicas C. , Mitchell D. G. , Lagg A. , Woch J. , Motschmann U. , Krimigis S. M. , Dougherty M. K.
Published: June 2007

Since Saturn orbit insertion (SOI), Cassini has performed numerous crossings of Saturn's inner moons' L shells. The Low‐Energy Magnetospheric Measurement System (LEMMS) has detected a large number of microsignatures in its lowest‐energy electron channels (20–100 keV) as well as in the MeV energy range. We have catalogued and analyzed more than 70 microsignatures in the LEMMS data from the first 22 Cassini orbits and have correlated their evolution with electron diffusive processes. Our results on the L‐dependence of the radial diffusion coefficients, DLL, show that radial microdiffusion driven by magnetic field impulses is the dominant mechanism to account for their refilling. The dependency of DLL from equatorial pitch angles also points toward this mechanism. The large scattering of the DLL values at Tethys and Dione suggest that these field impulses might be related to injections. Our analysis also supports the, inferred from pre‐Cassini studies, filtering effect by the icy moons on radially diffusing electrons, which starts at the orbit of Dione, at 6.28 Saturn radii, Rs. This is suggested primarily by the very low radial diffusion speeds and by the characteristics of four microsignatures attributed to the moons Mimas and Epimetheus that all seem to have been formed in energies between 1.6 and 3.5 MeV. Despite the low DLL, diffusing electrons can escape absorption and be transported in the inner magnetosphere due to nonaxisymmetric drift shells, which can be detected even along the orbit of Enceladus. We estimate that a significant contribution to the filtering comes from the core of the E ring. Our results also show that L displacements due to the nonaxisymmetric drift shells are orders of magnitude higher than the icy moon L shell variability due to the nonzero eccentricities and inclinations, and total plasma losses on the moon surfaces should be reevaluated. We also examine the energy dependence of DLL and we present a series of possible explanations for the faster depletion of microsignatures at MeV energies. Using the high‐energy resolution PHA channels we assess that this faster depletion could result partly from an increase of DLL with energy. The larger passbands of the high‐energy electron detectors could amplify the erosion of the microsignature signal.
Short‐term relationship between solar irradiances and equatorial peak electron densities
Authors: Wang X. , Eastes R. , Reinisch B. W. , Bailey S. , Valladares C. E. , Woods T.
Published: June 2007

The short‐term relationship of the equatorial peak electron density and the solar short‐wavelength irradiance is examined using foF2 observations from Jicamarca, Peru and recent solar irradiance measurements from satellites. Solar soft X‐ray measurements from both the Student Nitric Oxide Explorer (SNOE) (1998–2000) and Thermosphere Ionosphere Mesosphere Energetics Dynamics (TIMED) (2002–2004) satellites as well as extreme ultraviolet (EUV) measurements from the TIMED satellite are used. Soft X‐rays show similar or higher correlation with foF2 at short timescales (27 days or less) than EUV does, although the EUV correlation is higher for longer periods. For the short‐term variations, both SNOE and TIMED observations have a higher correlation in the morning (∼0.46) than in the afternoon (∼0.1). In the afternoon, SNOE observations have a higher correlation (∼0.2) with foF2 than the TIMED observations (∼0.1 correlation), which may be due to differences in the solar cycle. At morning times, foF2 has a ∼27‐day variation, consistent with the solar rotation rate. After noon, but not in the morning, a ∼13.5‐day variation consistently appears in foF2. This ∼13.5‐day variation is attributed to geomagnetic influences.
The plasmapause response to the southward turning of the IMF derived from sequential EUV images
Authors: Murakami Go , Hirai Mariko , Yoshikawa Ichiro
Published: June 2007

We statistically examined the plasmapause response to the southward turning of the interplanetary magnetic field (IMF) using sequential global images of the plasmasphere, in order to understand how the convection electric field propagates to the inner magnetosphere. The extreme ultraviolet (EUV) imager on the Imager for Magnetopause‐to‐Aurora Global Exploration satellite clearly observed inward motion of the plasmapause driven by the southward turning of the IMF. We surveyed the EUV data in the 2000–2001 period and found 16 events. Using the sequential EUV images, we calculated the plasmapause radial velocity, and then estimated the time development of the convection electric field at the plasmapause (Epp). Epp and the solar wind electric field derived from the measurement by the ACE satellite had very similar variations each other, but there surely was a time lag. Consequently, our research indicates that the plasmapause response to the southward turning of the IMF takes 10–30 min. This timescale suggests that the convection electric field penetrates from the magnetopause to the inner magnetosphere through the ionosphere.
Energetic particles in the paleomagnetosphere: Reduced dipole configurations and quadrupolar contributions
Authors: Vogt J. , Zieger B. , Glassmeier K.‐H. , Stadelmann A. , Kallenrode M.‐B. , Sinnhuber M. , Winkler H.
Published: June 2007

The Earth’s magnetosphere acts as a shield against highly energetic particles of cosmic and solar origin. On geological timescales, variations of the internal geomagnetic field can drastically alter the magnetospheric structure and dynamics. This paper deals with energetic particles in the paleomagnetosphere. Scaling relations for cutoff energies and differential particle fluxes during periods of reduced dipole moment are derived. Particular attention is paid to high rigidity galactic cosmic ray particles in the GV range and to lower rigidity solar energetic particles. We find that in the paleomagnetosphere of a strongly reduced dipole moment, solar protons of several tens of MeV may access the Earth’s atmosphere even at midlatitudes. Higher‐order core‐field components can widen the polar caps and open new particle‐entry regions around the equator. Potential field modeling of the paleomagnetosphere and magnetohydrodynamic (MHD) simulations are utilized to study the impact of solar particles on the Earth’s atmosphere for more complex field configurations that are likely to occur during geomagnetic polarity transitions.
Postseismic relaxation and aftershocks
Authors: Savage J. C. , Svarc J. L. , Yu Shui‐Beih
Published: June 2007

Perfettini et al. (2005) suggested that the temporal dependence of surface displacements u(t) measured in the epicentral area following an earthquake is related to N(t), the cumulative number of aftershocks, by the equation u(t) = a + bt + cN(t) + d(1 − e−αt), where a, b, c, d, and α are constants chosen to fit the data and t is the postearthquake time. N(t) appears in the expression for u(t) because both the aftershocks and a portion of u(t) are thought to be driven by the same source, postseismic fault creep at subseismogenic depths on the downdip extension of the coseismic rupture. We show that this equation with the actually observed N(t) fits the postseismic displacements recorded on several baselines following each of five earthquakes: 1999 M7.6 Chi‐Chi (Taiwan), 1999 M7.1 Hector Mine (southern California), 2002 M7.9 Denali (central Alaska), 2003 M6.5 San Simeon (central California), and 2004 M6.0 Parkfield (central California) earthquakes. Although there are plausible physical interpretations for each of the terms in the expression for u(t), the large number of adjustable constants (a, b, c, d, and α) involved in fitting the rather simple postseismic displacements diminishes the significance of the fit. Because the observed N(t) is well fit by the modified Omori's law, fault creep at depth presumably exhibits the same temporal dependence. That dependence could be explained if the rheology of the fault downdip from the coseismic rupture is consistent with ordinary transient creep. Montesi (2004) demonstrated that power law creep across a shear zone at depth would also produce that temporal signal.
Western Quebec seismic zone (Canada): Clustered, midcrustal seismicity along a Mesozoic hot spot track
Authors: Ma Shutian , Eaton David W.
Published: June 2007

The western Quebec seismic zone (WQSZ) is a 160‐km‐wide band of intraplate seismicity extending 500 km from the Adirondack Highlands (United States) to the Laurentian uplands (Canada). Previous authors have proposed that the WQSZ is localized over the Mesozoic track of the Great Meteor hot spot. Here we explore this hypothesis further by investigating regional seismicity characteristics. Focal mechanisms for WQSZ earthquakes, including a new mechanism for a moderate (mN 4.5) earthquake, reveal a pattern of reverse‐sense faulting with SW trending P axes changing to E‐W in the southern part of the zone. We introduce a simple box‐counting method to delineate spatial clusters, based on exceedance of random seismicity density. Combining this approach with focal depths from regional depth phase analysis, we find that seismicity with shallow focus (0–7 km) is characterized by a random spatial distribution, whereas earthquakes with an intermediate focal depth (8–18 km) are strongly clustered along a diffuse linear band trending N50°W. Earthquakes deeper than 18 km are confined to a few distinct clusters. These clusters are characterized by differing b values and, for at least one cluster, repeating events. Projection of hypocenters onto a deep seismic profile and comparison with preexisting crustal structures suggest that local reactivation of Precambrian structural features may have occurred; however, the Great Meteor hot spot track remains the only compelling explanation for the overall distribution of earthquakes. Proximity of seismicity clusters to historic and prehistoric earthquakes lends support to the hypothesis that modern seismicity may represent exceptionally long‐lived aftershocks of large past events.
A numerical study on nonresonant interactions of gravity waves in a compressible atmosphere
Authors: Huang Kai Ming , Zhang Shao Dong , Yi Fan
Published: June 2007

Applying a second‐order numerical scheme, nonresonant interactions of gravity waves in a compressible atmosphere are investigated. The numerical results show that the nonresonant interaction of the gravity waves does occur, and an apparent energy exchange among the interacting waves can be observed, which indicates that the gravity waves with different spatial and temporal scales can extensively interact. In the nonresonant interaction, the wave energy generally tends to transfer from the primary wave with the highest frequency to the secondary and excited waves, which is different from that in the resonant interaction. Under the same initial energy of the secondary wave, the final energy of the excited wave is almost proportional to the initial energy of the primary wave. When the initial energies of the primary waves are identical, the final energy of the excited wave increases slowly with the increasing initial energy of the secondary wave. Similar to that in the resonant interaction, in the nonresonant interaction, wave vector and frequency of the excited wave show temporal variability. The wave vectors of the interacting triad do not satisfy the matching conditions which should be obeyed in the weak interaction theory. We also investigate the effects of the background wind field and viscous dissipation on the nonresonant interaction. The positive and negative background winds show tendencies to strengthen and weaken the wave energy transfer, respectively. This also differs from the weak interaction theory, in which only a Doppler shift can be caused. The primary effect of the viscosity is to dissipate the energy of the interacting waves. The viscosity can hardly prevent the nonresonant excitation, suggesting that the restriction of amplitude threshold on the interaction in the presence of viscosity predicted by the weak interaction approximation seems to be rather loose. As in the resonant interaction, the principal energy exchange is finished before the waves depart from each other, which indicates that the interacting characteristic time does exist in the nonresonant interaction. The characteristic time and evolutions of wavelength and intrinsic frequency for the excited wave are insensitive to the small initial wave amplitudes and Gaussian packet widths of the interacting waves, horizontal background wind field, and viscosity. However, the characteristic time is relevant to the wavelengths of the interacting waves.
Chemistry of OH and HO2 radicals observed at Rishiri Island, Japan, in September 2003: Missing daytime sink of HO2 and positive nighttime correlations with monoterpenes
Authors: Kanaya Yugo , Cao Renqiu , Kato Shungo , Miyakawa Yuko , Kajii Yoshizumi , Tanimoto Hiroshi , Yokouchi Yoko , Mochida Michihiro , Kawamura Kimitaka , Akimoto Hajime
Published: June 2007

We used laser‐induced fluorescence to measure concentrations of OH and HO2 at Rishiri Island, Japan, during September 2003. The average maximum daytime concentrations were 2.7 × 106 cm−3 for OH and 5.9 pptv for HO2. The observed concentrations were compared to those predicted by a photochemical box model constrained by ancillary observations. During the daytime, the model overestimated HO2 levels by an average of 89% and OH levels by an average of 35%. This overestimate of OH was rectified when the model was constrained by observed HO2 levels, suggesting that loss processes of HO2 were missing in the model. We calculated the loss rates of HO2 required to bring the modeled HO2 levels into agreement with observed levels. We then studied processes that are capable of explaining the loss rates, including halogen chemistry, heterogeneous loss of HO2 on aerosol surfaces, and the possibility of more rapid HO2 + RO2 reactions than expected. In the nighttime, most of the observed hourly averaged OH and 10‐min‐averaged HO2 concentrations were statistically significant and fell in the ranges (0.7–5.5) × 105 cm−3 and 0.5–4.9 pptv, respectively. Both HO2 and OH concentrations showed strong positive correlations with total monoterpene concentrations, strongly suggesting that the radicals were produced via reactions of monoterpenes. The median nighttime modeled‐to‐observed ratios were 1.29 and 0.56 for HO2 and OH, respectively. These ratios dropped to 0.49 and 0.29 during the evening of 25 September, possibly related to the presence of unmeasured olefinic species or chemical reactions involving RO2 that are poorly represented in the model.
Water tank studies of atmospheric boundary layer structure and air pollution transport in upslope flow systems
Authors: Reuten C. , Steyn D. G. , Allen S. E.
Published: June 2007

Heated mountain slopes sometimes vent air pollutants out of the boundary layer over the slope top and at other times trap pollutants in closed circulations. Field, numerical, and water tank studies of fair weather atmospheric conditions over complex terrain have shown more complicated vertical distributions of temperature, moisture, and aerosols than over horizontal terrain. To study these phenomena, we analyze flow fields, densities, and dye distributions in a bottom‐heated salt‐stratified water tank over a 19° slope with adjacent plain and plateau and compare with field and numerical model data. Vertical layering of dye results from upslope and plain‐plateau circulations. The thermal boundary layer (TBL, the bottom layer up to neutral buoyancy height), coincides with the lower branches of these circulations. The return flow branches form elevated layers (EL) with properties intermediate between the TBL and environmental background. As heating continues, the TBL rapidly entrains the ELs, leading to deeper circulations with new ELs at greater heights. Field data suggest that successive formation and entrainment of ELs occurs at multiple scales in the atmosphere. If the aerosol loading of an EL is too high to distinguish it from the underlying TBL on lidar backscatter scans, then both layers and the associated closed circulation appear embedded in one deep backscatter boundary layer. The findings suggest defining the atmospheric boundary layer in complex terrain on the diurnal heating timescale rather than the commonly used 1‐hour timescale, which is more appropriate for flat terrain. We discuss conditions leading to venting versus trapping of air pollutants.
Detection, attribution, and sensitivity of trends toward earlier streamflow in the Sierra Nevada
Authors: Maurer E. P. , Stewart I. T. , Bonfils C. , Duffy P. B. , Cayan D.
Published: June 2007

Observed changes in the timing of snowmelt dominated streamflow in the western United States are often linked to anthropogenic or other external causes. We assess whether observed streamflow timing changes can be statistically attributed to external forcing, or whether they still lie within the bounds of natural (internal) variability for four large Sierra Nevada (CA) basins, at inflow points to major reservoirs. Streamflow timing is measured by “center timing” (CT), the day when half the annual flow has passed a given point. We use a physically based hydrology model driven by meteorological input from a global climate model to quantify the natural variability in CT trends. Estimated 50‐year trends in CT due to natural climate variability often exceed estimated actual CT trends from 1950 to 1999. Thus, although observed trends in CT to date may be statistically significant, they cannot yet be statistically attributed to external influences on climate. We estimate that projected CT changes at the four major reservoir inflows will, with 90% confidence, exceed those from natural variability within 1–4 decades or 4–8 decades, depending on rates of future greenhouse gas emissions. To identify areas most likely to exhibit CT changes in response to rising temperatures, we calculate changes in CT under temperature increases from 1 to 5°. We find that areas with average winter temperatures between −2°C and −4°C are most likely to respond with significant CT shifts. Correspondingly, elevations from 2000 to 2800 m are most sensitive to temperature increases, with CT changes exceeding 45 days (earlier) relative to 1961–1990.
Uncertainties in global aerosol simulations: Assessment using three meteorological data sets
Authors: Liu Xiaohong , Penner Joyce E. , Das Bigyani , Bergmann Dan , Rodriguez Jose M. , Strahan Susan , Wang Minghuai , Feng Yan
Published: June 2007

Current global aerosol models use different physical and chemical schemes and parameters, different meteorological fields, and often different emission sources. Since the physical and chemical parameterization schemes are often tuned to obtain results that are consistent with observations, it is difficult to assess the true uncertainty due to meteorology alone. Under the framework of the NASA global modeling initiative (GMI), the differences and uncertainties in aerosol simulations (for sulfate, organic carbon, black carbon, dust, and sea salt) solely due to different meteorological fields are analyzed and quantified. Three meteorological data sets available from the NASA Goddard Data Assimilation Office (DAO) general circulation model (GCM), the Goddard Institute for Space Studies (GISS) GCM, version II' and the NASA Goddard Global Modeling and Assimilation Office (GMAO), finite‐volume GCM (FVGCM) are used to drive the same aerosol model. The global sulfate and mineral dust burdens with FVGCM fields are 40% and 20% less than those with DAO and GISS fields, respectively, due to its larger precipitation. Meanwhile, the sea salt burden predicted with FVGCM fields is 56% and 43% higher than those with DAO and GISS, respectively, due to its stronger convection especially over the Southern Hemispheric Ocean. Sulfate concentrations at the surface in the Northern Hemisphere extratropics and in the middle to upper troposphere differ by a factor of 3 between the three meteorological data sets. The agreement between model calculated and observed aerosol concentrations in the surface source regions is similar for all three meteorological data sets. Away from the source regions, however, the comparisons with observations differ greatly for DAO, FVGCM, and GISS, and the performance of the model using different meteorological data sets varies depending on the site and the compared species. Sensitivity simulations with the NASA GEOS‐4 assimilated fields show that the interannual variability of aerosol concentrations can be higher than a factor of 2 depending on the location and season, which is generally, however, smaller than the differences due to using different meteorological data sets. Global annual average aerosol optical depth at 550 nm is 0.120–0.131 for the three meteorological data sets. However, the contributions from different aerosol components to this total optical depth differ significantly, which reflects differences in the aerosol spatial distributions. The global annual average anthropogenic and all‐sky aerosol direct forcing at the top‐of‐the atmosphere is estimated to be −0.75, −0.35, and −0.40 W m−2 for DAO, FVGCM, and GISS fields, respectively. Regional differences can be much larger (by a factor of 4–5) in the tropics over the ocean and in the polar regions.
Optical and chemical properties of marine aerosols over the central equatorial Pacific Ocean during the 2003 R/V Mirai cruise
Authors: Fujitani Yuji , Murao Naoto , Ohta Sachio , Endoh Tatsuo , Yamagata Sadamu
Published: June 2007

The optical and chemical properties of atmospheric aerosols were measured over the central equatorial Pacific Ocean (from 150°E to 160°W longitude, near the equator) during the R/V Mirai cruise of January 2003. In the area from 165°E to 160°W along the equator, concentrations of anthropogenic chemical components were low; the average concentration of nonsea salt sulfate was 0.28 μg m−3, that of vanadium was less than the detection limit, and those of elemental carbon and organic carbon were 0.009 and 0.09 μg‐C m−3. The scattering coefficients were low (3.2 × 10−6 m−1 on average), and the absorption coefficients were also extremely low (0.06 × 10−6 m−1 on average). The mean value of single scattering albedo was 0.98, with a standard deviation of 0.01, indicating that the measured aerosols were transparent and had low variability. The measurement results suggest that nonsea salt sulfate and organic carbon were from natural sources. Sea salt particles and nonsea salt sulfate composed a large fraction (94%) of the water‐soluble components of fine particles. Thus the water‐soluble components and organic materials from natural sources were primarily responsible for the scattering of solar radiation. The measurement results give typical values of the optical and chemical properties of aerosols in the unpolluted central equatorial Pacific Ocean.
A parameterization of the specific surface area of seasonal snow for field use and for models of snowpack evolution
Authors: Domine F. , Taillandier A.‐S. , Simpson W. R.
Published: June 2007

The specific surface area (SSA) of snow is needed to model air‐snow exchange of chemical species. SSA is related to many snow physical properties, such as albedo and permeability. However, it is not described in models of snowpack evolution, in part because it is difficult to measure. Snowpack models often predict snow grain shape and snow density, and the goal of this paper is to propose parameterizations of snow SSA, based on snow density and grain shape. SSA values of 345 snow samples from snowpacks of the Alpine, maritime, tundra and taiga types are presented. Samples are regrouped into three main types: fresh (F), recent (R), and aged (A) snows, with several subtypes referring to grain shapes. Overall, there is a clear inverse correlation between SSA and density, d. Empirical equations of the form SSA = A ln(d) + B are proposed for the F and R types. For aged snows, separate correlations are proposed for subtypes A1 (rounded grains), A2 (faceted crystals), A3 (depth hoar), and A4 (lightly melted snow). Within subtypes A1, A2, and A3, more elaborate classifications are made by considering the snowpack type (Alpine, taiga, or tundra). For A1, A2, and A3 types, different trends are related to different intensities of wind action, which increases in the order taiga, Alpine, and tundra. We finally propose three parameterizations of snow SSA with increasing sophistication, by correlating SSA to snow type, then to snow type and density, and finally to snow type, density, and snowpack type.
Decrease of light rain events in summer associated with a warming environment in China during 1961–2005
Authors: Qian Weihong , Fu Jiaolan , Yan Zhongwei
Published: June 2007

Based on daily rainfall and temperature data for the summer monsoon season in mainland China during 1961–2005, this paper demonstrated an overall decreasing trend in the frequency of light rain events in association with regional warming, and different local trends in the frequency of moderate rain events in association with atmospheric circulation anomalies. The frequencies of moderate and extreme rain events increase in eastern China centered over the middle‐lower reaches of the Yangtze River, but decrease in North China and Southwest China. This pattern of rainfall trends in China is different from that in the Indian monsoon area, where an increase of extreme rain events in the monsoon season during 1951–2000 was found, indicating different responses of regional monsoons to a warming environment.
A three‐dimensional kinetic‐fluid numerical code to study the equilibrium structure of the magnetotail: The role of electrons in the formation of the bifurcated current sheet
Authors: Greco A. , De Bartolo R. , Zimbardo G. , Veltri P.
Published: June 2007

In this work we present a new stationary three‐dimensional kinetic‐fluid code with ions represented by particles and electrons by a massless fluid. The magnetotail current sheet is modeled as a magnetic field reversal with a normal magnetic field component Bn. A cross tail electric field Ey is included. An ion test particle simulation is performed in these fields assuming an anisotropic plasma source at the magnetospheric lobes, and ion distribution functions with their moments, such as density, current, and temperature are obtained. The plasma is assumed to be quasineutral and we use the electron momentum equation (with me → 0 and without collisions) and the continuity equation to derive the electron current density. We set up an iterative technique to obtain a self‐consistent solution of our set of equilibrium model equations. We use this code to study how electrons influence the structure of the magnetotail current sheet and how they contribute to the formation of a double peak in the cross‐tail current density, which is observed very often by CLUSTER when crossing the neutral sheet. We find that the electron finite Larmor radius term and the electron drift term, are responsible for the formation of a double peak in the total current density even in those case where the ion current density does not display any bifurcated structure. We also obtained an electric field component normal to the current sheet, which is often observed. Another interesting and physically relevant result which we obtained, is the formation of counterstreaming beamlets in the plasma sheet at some distance from the current sheet, which were observed by Galileo spacecraft in 1990. Finally, we compare the simulation results with the most recent CLUSTER observations.
Bacterial peptidoglycan breaks down intestinal tolerance via mast cell activation: The role of TLR2 and NOD2
Authors: Wu Linda , Feng Bai‐Sui , He Shao‐Heng , Zheng Peng‐Yuan , Croitoru Kenneth , Yang Ping‐Chang
Published: June 2007

Intestinal microbes are believed to be involved in the pathogenesis of inflammatory bowel disease. Microbes and their products are generally well tolerated by intestinal epithelial cells in the intestinal tract of healthy individuals. It is of significance to understand what breaks down the established tolerance leading to intestinal barrier dysfunction and intestinal inflammation. T84 monolayer transported peptidoglycan (PGN) was determined by enzyme‐linked immune assay. Mast cell line HMC‐1 cell activation in response to PGN stimulation was observed with electron microscopy and measurement of histamine release. T84 monolayer barrier function was determined by recording the transepithelial electric resistance (TER) and measuring the permeability in response to PGN‐induced HMC‐1 cell activation. Expression of Toll‐like receptor (TLR) 2 and nucleotide‐binding oligomerization domain (NOD) 2 were determined by immunocytochemistry, real‐time reverse transcription (RT)‐PCR and Western blot. Exposure to PGN alone did not alter TER and permeability of T84 monolayers. T84 monolayers transported PGN from the apical chamber to the basal chamber of transwell system. TLR2 expressed on the surface of HMC‐1 cells. HMC‐1 cells absorbed PGN. HMC‐1 cells released histamine in response to the PGN stimulation, which was blocked by pretreatment with antibodies or small interfering RNA against TLR2 or NOD2. In a co‐culture system, T84 monolayer transported PGN activated HMC‐1 cells and increased the horseradish peroxidase flux. TLR2 mediated the PGN‐absorption in HMC‐1 cells. Blockade of TLR2 or NOD2 abolished PGN‐induced HMC‐1 cell activation and T84 monolayer barrier dysfunction. T84 monolayer transported PGN activates HMC‐1 cells to release chemical mediators to induce T84 monolayer dysfunction that are mediated by TLR2 and NOD2.
Discrete Kato-type theorem on inviscid limit of Navier-Stokes flows
Authors: Cheng Wenfang (Wendy) , Wang Xiaoming
Published: June 2007

The inviscid limit of wall bounded viscous flows is one of the unanswered central questions in theoretical fluid dynamics. Here we present a somewhat surprising result related to numerical approximation of the problem. More precisely, we show that numerical solutions of the incompressible Navier-Stokes equations converge to the exact solution of the Euler equations at vanishing viscosity and vanishing mesh size provided that small scales of the order of ν∕U in the directions tangential to the boundary are not resolved in the scheme. Here ν is the kinematic viscosity of the fluid and U is the typical velocity taken to be the maximum of the shear velocity at the boundary for the inviscid flow. Such a result is somewhat counterintuitive since the convergence is ensured even in the case that small scales predicted by the conventional theory of turbulence and boundary layer are not resolved since under-resolution (which is allowed in our theorem) in advection dominated problem usually leads to oscillation which inhibits convergence in general. The result also indicates possible difficulty in terms of numerical investigation of the vanishing viscosity problem if rigorous fidelity of the numerics is desired since we have to resolve at least small scales of the order of ν∕U which is much smaller than any small scales predicted by the conventional theory of turbulence. On the other hand, such a result can be viewed as a discrete version of our result [X. Wang, Indiana Univ. Math. J. 50, 223 (2001)] which generalized earlier the result of Kato [in Seminar on PDE, edited by S. S. Chern (Springer, NY, 1984)] where the relevance of a scale proportional to the kinematic viscosity to the problem of vanishing viscosity is first discovered.
Multiparameter estimation using only a chaotic time series and its applications
Authors: Huang Debin , Xing Guojing , Wheeler Diek W.
Published: June 2007

An important extension to the techniques of synchronization-based parameter estimation is presented. Based on adaptive chaos synchronization, several methods are proposed to dynamically estimate multiple parameters using only a scalar chaotic time series. In comparison with previous schemes, the presented methods decrease the cost of parameter estimation and are more applicable in practice. Numerical examples are used to demonstrate the effectiveness and robustness of the presented methods. As an example application, an implementation of multichannel digital communication is proposed, where multiparameter modulation is used to simultaneously transmit more than one digital message. From a theoretical perspective, such an encoding increases the difficulty to directly read out the message from the transmitted signal and decreases the implementation cost.