bluuebunny/crossref_metadata_2025 huggingface dataset:
Lebenszufriedenheit bei chronischen Erkrankungen
Authors: Fittig Eike , Schweizer Johannes , Rudolph Udo
Published: March 2007

Zusammenfassung. Die Prävalenz von Depression bei chronisch Erkrankten ist im Vergleich zur Allgemeinbevölkerung stark erhöht. Anhand einer Stichprobe von N = 405 chronisch erkrankten Patienten untersuchen wir die Auswirkungen dieses Zusammenhangs. Hierbei nehmen wir an, dass depressive Personen auf ungünstigere Formen der Krankheitsbewältigung zurückgreifen und subjektiv ein geringeres Ausmaß an sozialer Unterstützung erleben. Mittels multipler Regressionsanalysen (sensu Baron & Kenny, 1986 ) wurde in der vorliegenden Studie geprüft, ob Krankheitsbewältigung und die Wahrnehmung sozialer Unterstützung als Mediatoren zwischen Depressivität und subjektiver Lebenszufriedenheit fungieren. Die Ergebnisse bestätigen, dass eine geringere Lebenszufriedenheit bei depressiven, chronisch erkrankten Patienten tatsächlich auf ungünstigere Formen der Krankheitsbewältigung und subjektiv geringere Soziale Unterstützung zurückzuführen ist. Die Ergebnisse werden diskutiert im Hinblick auf zukünftige Maßnahmen zur Sekundärprävention.
Korrelate von Alkoholwirkungserwartungen im Jugendalter
Authors: Barnow Sven , Stopsack Malte , Spitzer Carsten , Freyberger Harald-J.
Published: March 2007

Zusammenfassung. Theoretischer Hintergrund: Positive Alkoholwirkungserwartungen stellen ein bedeutsames Risiko für problematischen Alkoholkonsum dar. Ziel dieser Studie war die Identifikation der Korrelate positiver Alkoholwirkungserwartungen (AE) im Jugendalter. Methode: 311 Jugendliche (Alter 12-18 Jahre) einer Allgemeinbevölkerungsstichprobe wurden bezüglich der Familiengeschichte einer Alkoholstörung (FHalk), Verhaltensproblemen, Zugehörigkeit zu einer substanzkonsumierenden Peergoup und Ausmaß an positiven AE untersucht. Ergebnisse: Kinder aus Familien mit Alkoholstörungen wiesen dann ausgeprägte positive AE (oberstes Terzil) auf, wenn sie zusätzlich ein hohes Ausmaß an Verhaltensproblemen hatten (Odds Ratio (OR): 6.5; 95% Konfidenzintervall (KI): 1.3-32.6). Jugendliche mit aggressiven und delinquenten Verhaltensproblemen zeigten positivere AE im Vergleich zu Jugendlichen ohne Verhaltensprobleme vor allem bezüglich Spannungsreduktion (OR: 2.0; KI: 1.1-3.6) und sozialer Kompetenz (OR: 2.3; KI: 1.3-4.3), während die Zugehörigkeit in einer substanzkonsumierenden Peergroup mit hohen Erwartungen an soziales Wohlbefinden (OR: 2.3; KI: 1.4-3.7) und Kompetenz (OR: 2.0; KI: 1.1-3.6) assoziiert war. Schlussfolgerungen: Präventions- und Interventionsprogramme zur Veränderung von Einstellungen zu Alkohol sollten speziell auf Jugendliche aus Hochrisikogruppen zugeschnitten werden, wobei sowohl individuelle Merkmale als auch Aspekte der familiären und nicht familiären Umwelt berücksichtigt werden müssen.
Der Ordnungseffekt im Psychotherapieprozess
Authors: Tschacher Wolfgang , Ramseyer Fabian , Grawe† Klaus
Published: March 2007

Zusammenfassung. Theoretischer Hintergrund: Selbstorganisation und Musterbildung sind zentrale Konzepte der Systemtheorie. Für Therapiesysteme wurde Musterbildung im Sinne eines Ordnungseffektes theoriegeleitet vorhergesagt. Fragestellung: Die vorliegende Studie prüft das Phänomen und die Validität der Ordnungszunahme an 30 Therapien und untersucht Zusammenhänge mit dem Therapieerfolg. Methode: Die Ordnungsmessung basiert auf Patienten- und Therapeutenstundenbögen. Als Ordnungsmaße wurden faktorenanalytische Verfahren und das Ordnungsmaß Ω nach Landsberg eingesetzt. Ergebnisse: Eine signifikante Ordnungszunahme in den Therapiesystemen ergibt sich mit allen verwendeten Verfahren. Dieser Ordnungseffekt geht nicht auf stereotype Antwortmuster zurück und hängt besonders mit interaktionellen Variablen zusammen. Schlussfolgerungen: Der Ordnungseffekt in Therapiesystemen erweist sich als replizierbarer und valider Befund, der mit der Qualität der Therapiebeziehung und dem Therapieoutcome verknüpft ist. Dies unterstreicht die Bedeutung von Selbstorganisationsprozessen bei Psychotherapien.
Making Sense of Family Violence
Authors: Fosco Gregory M. , DeBoard Renee L. , Grych John H.
Published: March 2007

Children who are exposed to interparental violence are at risk for a host of adjustment problems, but little is known about the processes that explain why children from violent families develop different patterns of adjustment. In this paper, we examine the role that children's perceptions and interpretations of aggression may play in shaping the impact of interparental violence on their short- and long-term functioning. Appraisals of interparental conflict have been linked to children's emotional and behavioral responses to conflict as well as their adjustment more broadly and offer a mechanism for understanding diverse outcomes in children who witness violence in the home. We explore how the appraisal process may differ in violent versus conflictual but nonviolent interactions, consider contextual factors that may influence this process, and outline directions for research investigating how children perceive and make sense of violence in intimate relationships.
Gender Differences in Coping Strategies in Children and Adolescents
Authors: Eschenbeck Heike , Kohlmann Carl-Walter , Lohaus Arnold
Published: March 2007

Abstract. The present study focuses on gender effects and interactions between gender, type of stressful situation, and age-group in coping strategies in childhood and adolescence. The sample consisted of N = 1990 children and adolescents (957 boys, 1033 girls; grade levels 3-8). Participants responded to a coping questionnaire (Fragebogen zur Erhebung von Stress und Stressbewältigung im Kindes- und Jugendalter, SSKJ 3-8; Lohaus, Eschenbeck, Kohlmann, & Klein-Heßling, 2006 ) with the five subscales: seeking social support, problem solving, avoidant coping, palliative emotion regulation, and anger-related emotion regulation. Repeated measures ANOVAs with Gender and Grade Level as the between-subject factors and Situation (social, academic) as the within-subject factor were performed separately for each of the subscales. In general, girls scored higher in seeking social support and problem solving, whereas boys scored higher in avoidant coping. These three main effects were further modified by significant Gender × Situation interactions and for both seeking social support and avoidant coping by significant Gender × Situation × Grade Level interactions. Compared to the academic situation (homework), gender differences were more pronounced for the social situation (argument with a friend), especially in adolescence. The results are discussed with respect to a gender-specific development of coping strategies.
Exploring Adult Personality and Psychopathy Tendencies in Former Childhood Hyperactive Delinquent Males
Authors: Freidenfelt Jenny , af Klinteberg Britt
Published: March 2007

The focus of this article is on (1) the possible influence of childhood hyperactive behavior on adult psychopathy, and (2) how adult, clinically rated, psychopathy tendencies are related to self-reported personality. The sample comprised 152 male subjects, including young lawbreakers (n = 98) and controls (n = 54), prospectively studied over their lifetime. Ratings of childhood behavior were obtained from a psychiatrist and data on adult personality (using the Karolinska Scales of Personality and a shortened form of the Eysenck Personality Questionnaire) and psychopathy were obtained using the Psychopathy Check List (PCL). Subjects with high PCL as adults (n = 36) scored higher than low PCL subjects (n = 116) on the majority of the personality dimensions studied, even when controlling for criminality. Former childhood hyperactive subjects (n = 26) displayed higher impulsivity and hostility than nonhyperactive subjects (n = 126) when criminality was controlled for. Among the high PCL group subjects there was an overrepresentation of childhood hyperactive males. They displayed significantly higher impulsivity and verbal aggression than their respective nonhyperactive counterparts and were characterized by extreme scores on several psychopathy-related personality scales. Further, there was a significant interaction effect between hyperactivity and PCL on the narrow/noninclusive form of impulsivity. The findings of the present personality-based approach were in favor of childhood hyperactivity being crucial as a risk indicator in the development of psychopathic tendencies.
The Relationship Between Self-Estimated and Test-Derived Scores of Personality and Intelligence
Authors: Furnham Adrian , Dissou Georgia
Published: March 2007

A total of 101 university students completed the full NEO-PI-R ( Costa & McCrae, 1992 ), assessing the five super-traits (domains) and 30 primary traits (facets), followed by four different cognitive ability tests. Two months later (before receiving feedback on their psychometric scores), they had estimated their own scores on all these variables (personality traits and ability tests), as well as that of a known friend. Results at the Big Five super-factor (domain) level indicated that participants could significantly predict/estimate all their own big five scores, particularly Neuroticism (r = .60). Correlations between estimates of their own intelligence scores and test-derived scores ranged from r = .51 to r = .59. They were, as predicted, much less successful in predicting their friend's scores. At the primary factor (facet) level, participants seemed best at predicting their six Neuroticism scores and less good predicting their six Agreeableness scores. A series of regressions looked at the extent to which self-estimated versus actual (test-derived) Big Five trait scores predicted self-estimated and actual intelligence on each of the four test scores. Self-estimated Conscientiousness significantly predicted various intelligence scores. Stable Open Introverts tended to give themselves higher self-estimates. The possible origins of academic hubris and humility are discussed.
Measuring Auditory Inspection Time in Primary School Children
Authors: Zajac Ian T. , Burns Nicholas R.
Published: March 2007

This study investigated the relationship between visual inspection time (VIT) and a new measure of auditory inspection time (AIT: see Parker, Crawford, & Stephen, 1999 ). The purpose was twofold: first, to understand the generality of the mechanism underpinning performance on visual IT tasks (VIT); second, to evaluate the efficacy of this new auditory task. Participants were 80 primary school children aged 10–12 years. They each completed AIT, VIT, and a marker test for each of general speediness (Gs), fluid ability (Gf), and crystallized ability (Gc). AIT and VIT were positively correlated with each other, and they both correlated with the marker of Gs. However, the data suggest that the nature of IT tasks changes as task difficulty increases. Thus, IT appears to be a purer measure of processing speed at longer exposure durations. These findings are discussed in relation to the methodology employed in IT estimation and in light of recent comments concerning the psychological complexity of IT.
Power Differences Between the Modified Brown-Forsythe and Mixed-Model Approaches in Repeated Measures Designs
Authors: Vallejo Guillermo , Fernández María P. , Livacic-Rojas Pablo E.
Published: March 2007

Abstract. This article compares the sensibility of the modified Brown-Forsythe (MBF) approach developed by Vallejo and Ato (2006) and a modified empirical generalized least squares (EGLS) method adjusted by the Kenward-Roger solution available in the SAS Institute's (2002) Proc Mixed program to detect the presence of an interaction effect under departures from covariance homogeneity and multivariate normality. Although none of the approaches demonstrated superior performance in all situations, our results indicate that the so-called EGLS method, based on the Akaike's Information Criterion or based on always assuming a unstructured between-subjects heterogeneous covariance pattern, was the most powerful alternative. Results also indicate that little power can be achieved with the EGLS method if the covariance matrix is specified correctly.
Methods for Restricting Maximum Exposure Rate in Computerized Adaptative Testing
Authors: Barrada Juan Ramon , Olea Julio , Ponsoda Vicente
Published: March 2007

Abstract. The Sympson-Hetter (1985) method provides a means of controlling maximum exposure rate of items in Computerized Adaptive Testing. Through a series of simulations, control parameters are set that mark the probability of administration of an item on being selected. This method presents two main problems: it requires a long computation time for calculating the parameters and the maximum exposure rate is slightly above the fixed limit. Van der Linden (2003) presented two alternatives which appear to solve both of the problems. The impact of these methods in the measurement accuracy has not been tested yet. We show how these methods over-restrict the exposure of some highly discriminating items and, thus, the accuracy is decreased. It also shown that, when the desired maximum exposure rate is near the minimum possible value, these methods offer an empirical maximum exposure rate clearly above the goal. A new method, based on the initial estimation of the probability of administration and the probability of selection of the items with the restricted method ( Revuelta & Ponsoda, 1998 ), is presented in this paper. It can be used with the Sympson-Hetter method and with the two van der Linden's methods. This option, when used with Sympson-Hetter, speeds the convergence of the control parameters without decreasing the accuracy.
Effect Sizes and F Ratios < 1.0
Authors: Voelkle Manuel C. , Ackerman Phillip L. , Wittmann Werner W.
Published: March 2007

Abstract. Standard statistics texts indicate that the expected value of the F ratio is 1.0 (more precisely: N/(N-2)) in a completely balanced fixed-effects ANOVA, when the null hypothesis is true. Even though some authors suggest that the null hypothesis is rarely true in practice (e.g., Meehl, 1990 ), F ratios < 1.0 are reported quite frequently in the literature. However, standard effect size statistics (e.g., Cohen's f) often yield positive values when F < 1.0, which appears to create confusion about the meaningfulness of effect size statistics when the null hypothesis may be true. Given the repeated emphasis on reporting effect sizes, it is shown that in the face of F < 1.0 it is misleading to only report sample effect size estimates as often recommended. Causes of F ratios < 1.0 are reviewed, illustrated by a short simulation study. The calculation and interpretation of corrected and uncorrected effect size statistics under these conditions are discussed. Computing adjusted measures of association strength and incorporating effect size confidence intervals are helpful in an effort to reduce confusion surrounding results when sample sizes are small. Detailed recommendations are directed to authors, journal editors, and reviewers.
Analysis of slope failures in submarine canyon heads: An example from the Gulf of Lions
Authors: Sultan Nabil , Gaudin Matthieu , Berne Serge , Canals Miquel , Urgeles Roger , Lafuerza Sara
Published: March 2007

To improve understanding of evolution of submarine canyons, a three‐dimensional slope stability model is applied to Bourcart Canyon in the western Gulf of Lions in the Mediterranean Sea. The model builds on previous work by Z. Chen and others, and it uses the upper bound theorem of plasticity to calculate the factor of safety of a kinematically admissible failing mass. Examples of three‐dimensional failure surfaces documented in the literature were used to test the model formulation. Model application to Bourcart Canyon employed the results of detailed stratigraphic analyses on the basis of data acquired by swath bathymetry, subbottom profiling, high‐resolution seismic reflection surveys, and piston coring. The sediment layers were also characterized using in situ geotechnical measurements and laboratory tests. The effects of three loading scenarios were analyzed: (1) earthquake shaking, (2) hemipelagic sedimentation, and (3) axial incision. These three mechanisms influenced the predicted volumes and shapes of slope failures along the flanks of Bourcart Canyon, and comparison of these predictions with failure geometries inferred from seafloor morphology showed that mass failures could account for the observed morphology along the canyon walls as well as a mechanism of canyon widening.
An abrupt change in the African monsoon at the end of the Younger Dryas
Authors: Talbot Michael R. , Filippi Maria Letizia , Jensen Niels Bo , Tiercelin Jean‐Jacques
Published: March 2007

High‐resolution studies of variations in the elemental and stable carbon‐ and nitrogen‐isotope composition of organic matter in cores from Lakes Malawi, Tanganyika, and Bosumtwi (tropical Africa) indicate an abrupt change in the wind‐driven circulation of these lakes that, within the limits of available chronologies, was contemporaneous with the end of the Younger Dryas in the northern hemisphere. The change was also coincident with shifts in surface winds recorded in cores from off the west and northeast coasts of Africa. A range of other proxies indicate that these changes in wind regime were accompanied by a marked increase in precipitation in the northern tropics. Africa south of ∼5°–10°S, on the other hand, initially suffered drought conditions. Together, the evidence suggests an abrupt northward translation of the African monsoon system at circa 11.5 ± 0.25 ka B.P. The data assembled here contribute to a growing body of work showing that the Younger Dryas was a major climatic excursion in tropical Africa. Furthermore, they add substance to recent suggestions that climatic events in the southern hemisphere may have played a significant role in the abrupt demise of the Younger Dryas.
Indonesian throughflow control of the eastern equatorial Pacific biogeochemistry
Authors: Gorgues T. , Menkes C. , Aumont O. , Dandonneau Y. , Madec G. , Rodgers K.
Published: March 2007

Two model simulations were performed to address the influence of the Indonesian throughflow (ITF) on the biogeochemical state of the equatorial Pacific. A simulation where the ITF is open is compared with an experiment where it is closed, and it is first shown that the impacts on the physical circulation are consistent with what has been found in previous modelling studies. In terms of biochemistry, closing the ITF results in increased iron concentration at the origin of the Equatorial Undercurrent (EUC). But the 11Sv of water otherwise transferred to the Indian Ocean remain in the equatorial Pacific, which result in a 30 m deepening of the thermocline/ferricline in the eastern Pacific. This deepening decreases the iron concentration of the equatorial wind driven upwelled water and cancels the iron increase advected by the EUC. The iron decrease of the equatorial upwelled water leads to decrease primary production by 15% along the equator.
Linking future aerosol radiative forcing to shifts in source activities
Authors: Koch Dorothy , Bond Tami C. , Streets David , Unger Nadine
Published: March 2007

We model future direct radiative forcings of the major anthropogenic aerosol species, sulfate, black and organic carbon, within industrial, power, transport, and residential sectors and biomass burning. A sectoral perspective helps to inform mitigation directions. More accurate projections are facilitated by recent carbonaceous aerosol emission estimates that incorporate projected technology changes, now available for the Intergovernmental Panel on Climate Change scenarios A1B and B1, for 2030 and 2050. Net present‐day model anthropogenic forcing is −0.11 W m−2. By 2050 this doubles (A1B) or drops by 30% (B1), depending mostly on sulfate changes in the industry and power sectors. Present‐day (non‐biomass burning) BC forcing comes mostly from residential sources (+0.09 W m−2), however this is projected to decrease by more than a factor of 10 by 2050. Future BC forcing is projected to come mostly from transport, changing from +0.06 W m−2 in 2000 to +0.04 (B1) or +0.07 W m−2 (A1B) by 2050.
Impact of the 2002, Southern Hemisphere, stratospheric warming on the tropical cirrus clouds and convective activity
Authors: Eguchi Nawo , Kodera Kunihiko
Published: March 2007

Tropical cirrus cloud variation associated with the southern hemisphere stratospheric sudden warming (SSW) in September 2002 was investigated using data from MODIS/Terra. During the SSW, enhanced wave forcings induced upwelling in the tropical stratosphere, which further extended into the equatorial troposphere. This initial perturbation of the tropospheric upwelling developed in the southern tropical troposphere through increased mass‐ and water vapor convergence in the lower level leading to deep convection. Cirrus cloud was first formed by the low temperature due to upwelling associated with the SSW, and it persisted for a few weeks after the end of SSW due to the low temperature associated with the Kelvin‐wave response to a deep convection triggered by the SSW.
Geophysically consistent values of the perovskite to post‐perovskite transition Clapeyron slope
Authors: Hernlund J. W. , Labrosse S.
Published: March 2007

The double‐crossing hypothesis posits that post‐perovskite bearing rock in Earth's D″ layer exists as a layer above the core‐mantle boundary bounded above and below by intersections between a curved thermal boundary layer geotherm and a relatively steep phase boundary. Increasing seismic evidence for the existence of pairs of discontinuities predicted to occur at the top and bottom of this layer motivates an examination of the consistency of this model with mineral physics constraints for the Clapeyron slope of this phase transition. Using independent constraints for a lower bound on temperature in Earth's deep mantle and the temperature of Earth's inner core boundary, we show that a post‐perovskite double‐crossing is inconsistent with plausible core temperatures for a Clapeyron slope less than about 7 MPa/K, with the higher range of experimental values yielding better agreement with recent estimates of the melting temperature of Earth's core.
Anomalous 20th century tree growth, Mackenzie Delta, Northwest Territories, Canada
Authors: Pisaric Michael F. J. , Carey Sean K. , Kokelj Steven V. , Youngblut Donald
Published: March 2007

A number of contemporary dendroecological studies from northwestern North America have highlighted a divergence in growth trends during recent decades. These studies suggest that warmer temperatures are now exceeding the physiological threshold of some northern tree species, or perhaps are contributing to increased drought stress as current precipitation is insufficient to offset increasing water demands under warmer conditions. Here we document additional evidence of these diverging growth trends from the Mackenzie Delta region of Canada and show they are anomalous to the twentieth century. Using wavelet coherency analyses we demonstrate that our white spruce tree ring chronologies exhibit little divergence from one another during the past four centuries, but coherency of the data‐sets rapidly break down after the 1930s.
Potential for attenuation‐based estimations of rainfall rate from CloudSat
Authors: Matrosov Sergey Y.
Published: March 2007

Attenuation of radar signals in rain increases with frequency while the variability of non‐attenuated reflectivity of rainfall diminishes as resonance scattering effects become more pronounced at higher radar frequencies. At mm‐wavelength frequencies, attenuation often becomes the dominant factor responsible for apparent reflectivity changes in vertical. This study presents an attenuation‐based method to retrieve vertical profiles of rain rate from nadir‐pointing W‐band (94 GHz) radars. The quantitative assessments of retrieval errors are discussed, and an illustration of the retrievals using measurements from the spaceborne 94 GHz CloudSat radar is shown. As a consistency check, the spaceborne W‐band radar retrievals are compared with concurrent estimates from a ground‐based weather surveillance radar.
Effects of ice melting on GRACE observations of ocean mass trends
Authors: Chambers Don P. , Tamisiea Mark E. , Nerem R. Steven , Ries John C.
Published: March 2007

The Gravity Recovery and Climate Experiment (GRACE) was designed to measure variations in the Earth's gravity field from space at monthly intervals. Researchers have used these data to measure changes in water mass over various regions, including the global oceans and continental ice sheets covering Greenland and Antarctica. However, GRACE data must be smoothed in these analyses and the effects of geocenter motions are not included. In this study, we examine what effect each of these has in the computation of ocean mass trends using a simulation of ice melting on Greenland, Antarctica, and mountain glaciers. We find that the recovered sea level change is systematically lower when coefficients are smoothed and geocenter terms are not included. Assuming current estimates of ice melting, the combined error can be as large as 30–50% of the simulated sea level rise. This is a significant portion of the long‐term sea level change signal, and needs to be considered in any application of GRACE data to estimating long‐term trends in sea level due to gain of water mass from melting ice.
Focusing of electromagnetic beams in ionosphere with finite thermal conduction
Authors: Sodha Mahendra Singh , Sharma Ashutosh , Agarwal Sujeet Kumar
Published: March 2007

In this communication the focusing/defocusing of (1) a single Gaussian electromagnetic beam, (2) a number of coaxial Gaussian electromagnetic beams, and (3) a Gaussian ripple on an electromagnetic beam of uniform irradiance in the ionosphere has been investigated in the paraxial approximation. The nonlinearity in the dielectric function, responsible for the focusing/defocusing arises from the redistribution of the electron density, caused by the nonuniform distribution of electron temperature, determined by the Ohmic heating of the electrons and the energy loss of electrons on account of collisions and thermal conduction. The wave frequencies have been assumed to be much larger than the electron collision frequency and the gyrofrequency. A self‐consistent solution of the electromagnetic wave equation, energy balance equation (considering the solar radiation), and Fourier's equation of heat conduction has been obtained in the paraxial approximation; the available database for the midlatitude daytime ionosphere has been used for numerical computation. It is seen that as the thermal conductivity increases, the axial electron temperature and its radial gradient decrease, with the net effect that the nonlinearity in the dielectric function increases. This causes the critical curves to rise up and the two humps to get more pronounced as the thermal conduction becomes more important.
Coseismic fold scarps and their kinematic behavior in the 1999 Chi‐Chi earthquake Taiwan
Authors: Chen Yue‐Gau , Lai Kuang‐Yin , Lee Yuan‐Hsi , Suppe John , Chen Wen‐Shan , Lin Yu‐Nong N. , Wang Yu , Hung Jih‐Hao , Kuo Yu‐Ting
Published: March 2007

Discrete scarps that are created or reactivated during large earthquakes are a locus of concentrated hazard. A number of the coseismic scarps activated in the 1999 Chi‐Chi earthquake are actually fold scarps, which display several types of ground deformation characterized by localized folding and are distinct from classic fault scarps, which form by a fault cutting the surface. This paper documents and analyzes fold scarps that formed or reactivated in the 1999 Chi‐Chi Taiwan earthquake. Our results show the Chi‐Chi fold scarps can be generally divided into two types: (1) those associated with folding ahead of the tip of a blind thrust fault at shallow depths and (2) those associated with folding by kink band migration above fault bends at substantial depths ranging from ∼0.8 to 5 km). The previously published trishear model can be applied to model the former type, while a new curved hinge kink band migration model is provided to describe the behavior of the latter type. A key feature of fold scarps of the second type is that hinge zones are typically wide (25–100 m) relative to the displacement in a single earthquake (1–10 m), which exerts a significant control on fold scarp morphology and evolution. Because the coseismic strains of both types of fold scarps display relatively wide deformation zones (10–100 m) relative to fault scarps, wider set‐back zones might be appropriate from a public policy point of view to alleviate the risk to structural damage and collapse resulting from permanent ground deformation.
Poroelastic finite difference modeling of seismic attenuation and dispersion due to mesoscopic‐scale heterogeneity
Authors: Masson Y. J. , Pride S. R.
Published: March 2007

Seismic attenuation and dispersion are numerically determined for computer‐generated porous materials that contain arbitrary amounts of mesoscopic‐scale heterogeneity in the porous continuum properties. The local equations used to determine the poroelastic response within such materials are those of Biot (1962). Upon applying a step change in stress to samples containing mesoscopic‐scale heterogeneity, the poroelastic response is determined using finite difference modeling, and the average strain throughout the sample computed, along with the effective complex and frequency‐dependent elastic moduli of the sample. The ratio of the imaginary and real parts of these moduli determines the attenuation as a function of frequency associated with the modes of applied stress (pure compression and pure shear). By having a wide range of heterogeneity present, there exists a wide range of relaxation frequencies in the response with the result that the curves of attenuation as a function of frequency are broader than in existing analytical theories based on a single relaxation frequency. Analytical explanations are given for the various high‐frequency and low‐frequency asymptotic behavior observed in the numerical simulations. It is also shown that the overall level of attenuation of a given sample is proportional to the square of the incompressibility contrasts locally present.
Hygroscopic growth of atmospheric and model humic‐like substances
Authors: Dinar E. , Taraniuk I. , Graber E. R. , Anttila T. , Mentel T. F. , Rudich Y.
Published: March 2007

The hygroscopic growth (HG) of humic‐like substances (HULIS) extracted from smoke and pollution aerosol particles and of Suwannee River fulvic acid (SRFA, bulk and fractions of different molecular weight) was measured by humidity tandem differential mobility analyzer (H‐TDMA). By characterizing physical and chemical parameters such as molecular weight, elemental composition, and surface tension, we test the effect of these parameters on particle interactions with water vapor. For molecular weight‐fractionated SRFA fractions, the growth factor at 90% relative humidity was generally inversely proportional to the molecular weight. HULIS extracts from ambient particles are more hygroscopic than all the SRFA fractions and exhibit different hygroscopic properties depending on their origin and residence time in the atmosphere. The results point out some dissimilarities between SRFA and aerosol‐derived HULIS. The cloud condensation nuclei (CCN) behavior of the studied materials was predicted on the basis of hygroscopic growth using a recently introduced approach of Kreidenweis et al. (2005) and compared to CCN activity measurements on the same samples (Dinar et al., 2006). It is found that the computational approach (Kreidenweis et al., 2005) works reasonably well for SRFA fractions but is limited in use for the HULIS extracts from aerosol particles. The difficulties arise from uncertainties associated with HG measurements at high relative humidity, which leads to large errors in the predicted CCN activity.
Latitudinal and seasonal variations of inertial gravity wave activity in the lower atmosphere over central China
Authors: Zhang Shao Dong , Yi Fan
Published: March 2007

Gravity wave activities and background dynamical structure in the troposphere and lower stratosphere (TLS) over five stations at latitudes from 10°N to 40°N were statistically studied by using the data from Radiosonde observation on a twice daily basis at 0800 and 2000 LT. The background dynamical structure exhibits evident latitudinal and seasonal variations and has a profound influence on inertial gravity waves in the TLS. In the analyses of inertial gravity waves, according to the background structures, the observation height coverage is divided into two segments, which are the tropospheric (0–10 km) and lower‐stratospheric segments (18–25 km). The observational results indicate that the tropospheric jet is the most important excitation source for gravity waves both in the troposphere and lower stratosphere, and it plays different roles in determining the morphology of gravity waves in these two segments. The jet‐excited gravity waves in the troposphere can propagate both upward and downward, and only part of the upward‐propagating waves can penetrate into the stratosphere because of the Doppler shifting by the jet, while in the lower stratosphere, gravity waves excited by the tropospheric jet propagate upward. Most differences between the tropospheric and lower‐stratospheric results can be explained from the linear dispersion relations of gravity waves and the Doppler shifting by the strong tropospheric jet. However, such an explanation is qualitative rather than quantitative. Generally, the observations reveal that the tropospheric gravity waves are mainly controlled by their excitation sources, implying the wave characteristics may be regarded as (at least an indicator of) the wave excitation source characteristics. These results suggest that in order to attain a more realistic source parameterization for gravity waves propagating in the middle and upper atmosphere, more attention should be paid to the gravity waves in the troposphere. Moreover, the causes of the pronounced peak of lower‐stratospheric gravity wave intensity at tropical latitudes revealed by previous observations are also discussed.
Infiltration from a strip source
Authors: Warrick A. W. , Lazarovitch N.
Published: March 2007

This study addresses infiltration from strip sources of water on the soil surface. The problem arises as the limiting case of furrow irrigation as well as for closely spaced surface drip emitters. Previously, the most common approach used for describing flow from strip sources was numerical modeling based on Richards' equation. This work investigates a third approach borrowed from previous applications for infiltration from disc sources. The assumption is that when the cumulative infiltration is expressed per unit area of the wetted strip, the difference of that value and one‐dimensional infiltration is linear with time. We test the assumption directly by doing numerical experiments with six representative soils and using various strip widths, boundary, and initial water contents. The general conclusions are that the differences between the cumulative infiltration per unit source area for a strip and a planar source are linearly related to time but that a single value of the proportionality factor γ is generally inadequate. Values of γ are found between 0.64 and 1.16. An effort was made to relate γ to soil hydraulic parameters and strip width as well as to the boundary and initial conditions. Once γ is defined, the strip infiltration follows immediately if the corresponding one‐dimensional solution is known without the necessity of performing a two‐dimensional simulation.
No Effect of Low-Dose Statins Treatment on Cerebral Blood Flow in Humans with Atherosclerotic Cerebrovascular Disease
Authors: Derdeyn Colin P , Carpenter David A , Videen Tom O , Grubb Robert L , Powers William J
Published: March 2007

Animal studies have suggested that the reduction in stroke risk observed with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) therapy is owing to an increase in basal cerebral blood flow (CBF). The purpose of the study was to determine if statin therapy was associated with increased CBF in humans with cerebrovascular atherosclerotic disease. Quantitative measurements of CBF were obtained on study entry in 97 patients with carotid artery occlusion enrolled in a prospective study of cerebral hemodynamics and stroke risk. This study represents a post hoc analysis of CBF measurements based on whether patients were receiving statin therapy at the time of CBF measurement. Global and regional CBF (including hemispheric, basal ganglia, and arterial borderzones), and baseline clinical, epidemiologic, and laboratory stroke risk factors were compared between the two groups. Nineteen of the 97 patients were on a statin agent on study entry. The statin group was younger, had significantly lower LDL levels and included more women. Statin therapy was not associated with higher baseline values of CBF in global or regional analyses. Mean middle cerebral artery territory CBF (± s.d.) ipsilateral to the occluded carotid artery was 37.6 ± 12.7 mL/100 g min for the statin group ( n = 19) compared with 38.6 ± 12.7 mL/100 g min for the nonstatin group ( n = 78). Contralateral values were 42.9 ± 13.5 and 44.2 ± 13.3 mL/100 g min for the statin and nonstatin groups, respectively. We conclude that the stroke risk reduction observed with statin therapy in humans likely involves mechanisms other than an increased basal CBF.
Angiopoietin1/TIE2 and VEGF/FLK1 Induced by MSC Treatment Amplifies Angiogenesis and Vascular Stabilization after Stroke
Authors: Zacharek Alex , Chen Jieli , Li Ang , Cui Xu , Li Yi , Roberts Cynthia , Feng Yifan , Gao Qi , Chopp Michael
Published: March 2007

Bone marrow stromal cells (MSCs) increase vascular endothelial growth factor (VEGF) expression and promote angiogenesis after stroke. Angiopoietin-1 (Ang1) and its receptor Tie2 mediate vascular integrity and angiogenesis as does VEGF and its receptors. In this study, we tested whether MSC treatment of stroke increases Ang1/Tie2 expression, and whether Ang1/Tie2 with VEGF / vascular endothelial growth factor receptor 2 (VEGFR2) (Flk1), in combination, induced by MSCs enhances angiogenesis and vascular integrity. Male Wistar rats were subjected to middle cerebral artery occlusion (MCAo) and treated with or without MSCs. Marrow stromal cell treatment significantly decreased blood—brain barrier (BBB) leakage and increased Ang1, Tie2, and occludin (a tight junction protein) expression in the ischemic border compared with MCAo control. To further test the mechanisms of MSC-induced angiogenesis and vascular stabilization, cocultures of MSCs with mouse brain endothelial cells (MBECs) or astrocytes were performed. Supernatant derived from MSCs cocultured with MBECs significantly increased MBEC expression of Ang1/Tie2 and Flk1 compared with MBEC alone. Marrow stromal cells cocultured with astrocytes also significantly increased astrocyte VEGF and Ang1/Tie2 expression compared with astrocyte culture alone. Conditioned media from MSCs alone, and media from cocultures of MSCs with astrocytes or MBECs, all significantly increased capillary tube-like formation of MBEC compared with control Dulbecco's modified Eagle's medium media. Inhibition of Flk1 and/or Ang1 significantly decreased MSC-induced MBEC tube formation. Knockdown of Tie2 expression in MBECs significantly inhibited MSC-induced tube formation. Our data indicate MSC treatment of stroke promotes angiogenesis and vascular stabilization, which is at least partially mediated by VEGF/Flk1 and Ang1/Tie2.
Leg crossing with muscle tensing, a physical counter-manoeuvre to prevent syncope, enhances leg blood flow
Authors: Groothuis Jan T. , van Dijk Nynke , ter Woerds Walter , Wieling Wouter , Hopman Maria T. E.
Published: March 2007

In patients with orthostatic intolerance, the mechanisms to maintain BP (blood pressure) fail. A physical counter-manoeuvre to postpone or even prevent orthostatic intolerance in these patients is leg crossing combined with muscle tensing. Although the central haemodynamic effects of physical counter-manoeuvres are well documented, not much is known about the peripheral haemodynamic events. Therefore the purpose of the present study was to examine the peripheral haemodynamic effects of leg crossing combined with muscle tensing during 70° head-up tilt. Healthy subjects (n=13) were monitored for 10 min in the supine position followed by 10 min in 70° head-up tilt and, finally, for 2 min of leg crossing with muscle tensing in 70° head-up tilt. MAP (mean arterial BP), heart rate, stroke volume, cardiac output and total peripheral resistance were measured continuously by Portapres. Leg blood flow was measured using Doppler ultrasound. Leg vascular conductance was calculated as leg blood flow/MAP. A significant increase in MAP (13 mmHg), stroke volume (27%) and cardiac output (18%), a significant decrease in heart rate (−5 beats/min) and no change in total peripheral resistance during the physical counter-manoeuvre were observed when compared with baseline 70° head-up tilt. A significant increase in leg blood flow (325 ml/min) and leg vascular conductance (2.9 arbitrary units) were seen during the physical counter-manoeuvre when compared with baseline 70° head-up tilt. In conclusion, the present study indicates that the physical counter-manoeuvre of leg crossing combined with muscle tensing clearly enhances leg blood flow and, at the same time, elevates MAP.
Theoretical investigation of the alkaline-earth dihydrides from relativistic all-electron, pseudopotential, and density-functional study
Authors: Lim Ivan S. , Lee Yoon Sup
Published: March 2007

Highly precise ground state geometries, harmonic vibrational frequencies and force constants of alkaline-earth dihydrides from CaH2 to RaH2 are obtained using relativistic small-core energy-consistent effective core potentials at the coupled-cluster level. The results are compared with all-electron as well as density functional calculations. All-electron results, in particular, clearly show the importance of relativistic effects in the properties considered in this paper. The monotonic trends in the geometries are explained in terms of second-order perturbation theory. Trends in the force constants are monotonic except for the bending mode where an anomaly occurs from BaH2 to RaH2. It is rationalized in terms of reduced s-d hybridization due to relativity, which is shown to be an energy effect attributed to the stabilization of the s orbital. The pseudopotentials show an excellent performance in comparison with all-electron methods and are therefore successfully transferred to molecular cases. The density functional methods, however, suffer from functional dependencies with B3LYP performing the best in this case.
Folding simulations with novel conformational search method
Authors: Son Won-Joon , Jang Soonmin , Pak Youngshang , Shin Seokmin
Published: March 2007

A novel scheme for fast conformational search has been developed by combining the replica exchange method (REM) with the generalized effective potential concept. The new method, referred to Q-REM [S. Jang et al. Phys. Rev. Lett. 91, 058305 (2003)], is expected to provide a useful alternative to the conventional REM for effective conformational sampling of complex systems. The authors have performed folding simulations of the Trp-cage miniprotein using Q-REM. All atom level simulations with generalized Born solvent access-area solvation model show that successful folding can be observed with much smaller number of replicas in Q-REM compared to the conventional REM. It can be concluded that the new method has potential to significantly improve sampling efficiency, allowing simulations of more challenging systems.
Nuclear magnetic resonance restricted diffusion between parallel planes in a cosine magnetic field: An exactly solvable model
Authors: Grebenkov Denis S.
Published: March 2007

We propose a theoretical and numerical analysis of restricted diffusion between parallel planes in a cosine magnetic field. The specific choice of this spatial profile as proportional to an eigenfunction of the Laplace operator in this confining geometry considerably simplifies the underlying mathematics. In particular, exact and explicit relations for several moments of the total phase accumulated by diffusing spins are derived. These relations are shown to provide good approximations for the typical case of a linear magnetic field gradient, for which the theoretical analysis was in general limited to the second moment. We study the structure and the properties of the higher order moments which are responsible for the breakdown of the “Gaussian phase approximation” (GPA) at intense magnetic fields. The limits of applicability of the GPA for nonlinear magnetic fields and the transition to the localization regime are discussed. In particular, a diagram of different restricted diffusion regimes is presented.
Effects of a-Si:H layer thicknesses on the performance of a-Si:H∕c-Si heterojunction solar cells
Authors: Fujiwara Hiroyuki , Kondo Michio
Published: March 2007

We have fabricated hydrogenated amorphous silicon (a-Si:H)∕crystalline silicon (c-Si) heterojunction solar cells with different a-Si:H layer thicknesses, in order to determine effects of a-Si:H layer thicknesses on the performance of a-Si:H∕c-Si solar cells. The thicknesses of a-Si:H p-i layers formed on a n-type c-Si substrate were controlled accurately on the atomic scale by applying real-time spectroscopic ellipsometry during the a-Si:H growth. With increasing a-Si:H p-i layer thicknesses, the open-circuit voltage (Voc) and fill factor increase drastically up to 40Å (i layer) and 30Å (p layer), whereas the short-circuit current density (Jsc) reduces gradually. By using optimum a-Si:H layer thicknesses (i∕p=40∕30Å), we obtained a solar cell efficiency of 16.1% without incorporating surface texture and a back-surface field structure. Quite interestingly, the optimum a-Si:H i-layer thickness (40Å) shows good correlation with a SiH2-rich interface structure formed at the a-Si:H∕c-Si heterointerface, suggesting that the optimum i-layer thickness is governed by the interface properties of the a-Si:H∕c-Si. Quantum efficiency measurements further revealed that the influence of a-Si:H layer thickness on the solar cell is quite different between a-Si:H p and i layers. Based on results obtained from this study, we discuss the roles of a-Si:H p-i layers incorporated in a-Si:H∕c-Si heterojunction solar cells.
Structure and dynamics of the hydration shells of the Al3+ ion
Authors: Bylaska Eric J. , Valiev Marat , Rustad James R. , Weare John H.
Published: March 2007

First principles simulations of the hydration shells surrounding Al3+ ions are reported for temperatures near 300°C. The predicted six water molecules in the octahedral first hydration shell were found to be trigonally coordinated via hydrogen bonds to 12s shell water molecules in agreement with the putative structure used to analyze the x-ray data, but in disagreement with the results reported from conventional molecular dynamics using two-and three-body potentials. Bond lengths and angles of the water molecules in the first and second hydration shells and the average radii of these shells also agreed very well with the results of the x-ray analysis. Water transfers into and out of the second solvation shell were observed to occur on a picosecond time scale via a dissociative mechanism. Beyond the second shell the bonding pattern substantially returned to the tetrahedral structure of bulk water. Most of the simulations were done with 64 solvating water molecules (20ps). Limited simulations with 128 water molecules (7ps) were also carried out. Results agreed as to the general structure of the solvation region and were essentially the same for the first and second shell. However, there were differences in hydrogen bonding and Al–O radial distribution function in the region just beyond the second shell. At the end of the second shell a nearly zero minimum in the Al–O radial distribution was found for the 128 water system. This minimum is less pronounced minimum found for the 64 water system, which may indicate that sizes larger than 64 may be required to reliably predict behavior in this region.