bluuebunny/crossref_metadata_2025 huggingface dataset:
Adjusting for publication bias in the presence of heterogeneity
Authors: Terrin Norma , Schmid Christopher H. , Lau Joseph , Olkin Ingram
Published: June 2003

It is known that the existence of publication bias can influence the conclusions of a meta‐analysis. Some methods have been developed to deal with publication bias, but issues remain. One particular method called ‘trim and fill’ is designed to adjust for publication bias. The method, which is intuitively appealing and comprehensible by non‐statisticians, is based on a simple and popular graphical tool called the funnel plot. We present a simulation study designed to evaluate the behaviour of this method. Our results indicate that when the studies are heterogeneous (that is, when they estimate different effects), trim and fill may inappropriately adjust for publication bias where none exists. We found that trim and fill may spuriously adjust for non‐existent bias if (i) the variability among studies causes some precisely estimated studies to have effects far from the global mean or (ii) an inverse relationship between treatment efficacy and sample size is introduced by the studies' a priori power calculations. The results suggest that the funnel plot itself is inappropriate for heterogeneous meta‐analyses. Selection modelling is an alternative method warranting further study. It performed better than trim and fill in our simulations, although its frequency of convergence varied, depending on the simulation parameters. Copyright © 2003 John Wiley & Sons, Ltd.
Experimental design and sample size determination for testing synergism in drug combination studies based on uniform measures
Authors: Tan Ming , Fang Hong‐Bin , Tian Guo‐Liang , Houghton Peter J.
Published: June 2003

In anticancer drug development, the combined use of two drugs is an important strategy to achieve greater therapeutic success. Often combination studies are performed in animal (mostly mice) models before clinical trials are conducted. These experiments on mice are costly, especially with combination studies. However, experimental designs and sample size derivations for the joint action of drugs are not currently available except for a few cases where strong model assumptions are made. For example, Abdelbasit and Plackett proposed an optimal design assuming that the dose–response relationship follows some specified linear models. Tallarida et al. derived a design by fixing the mixture ratio and used a t‐test to detect the simple similar action. The issue is that in reality we usually do not have enough information on the joint action of the two compounds before experiment and to understand their joint action is exactly our study goal. In this paper, we first propose a novel non‐parametric model that does not impose such strong assumptions on the joint action. We then propose an experimental design for the joint action using uniform measure in this non‐parametric model. This design is optimal in the sense that it reduces the variability in modelling synergy while allocating the doses to minimize the number of experimental units and to extract maximum information on the joint action of the compounds. Based on this design, we propose a robust F‐test to detect departures from the simple similar action of two compounds and a method to determine sample sizes that are economically feasible. We illustrate the method with a study of the joint action of two new anticancer agents: temozolomide and irinotecan. Copyright © 2003 John Wiley & Sons, Ltd.
Displacement control of isolated structures with semi‐active control devices
Authors: Loh Chin‐Hsiung , Wu L. Y. , Lin P. Y.
Published: June 2003

This study investigates the application of a semi‐active control method utilizing a magnetorheological (MR) damper to reduce the response of an isolated structure subjected to earthquake excitations. A series of performance tests were carried out on a 2 kN MR damper and the Bouc–Wen model was utilized to establish the numerical model of the MR device. A fuzzy logic control algorithm was then applied to establish the controller. Results of numerical simulation indicated that the established control algorithm is useful to reduce displacement and acceleration responses of base‐isolated structures. Copyright © 2003 John Wiley & Sons, Ltd.
Predictive controlled stiffness devices in MDOF structures
Authors: Ribakov Y.
Published: June 2003

This paper presents a study of a predictive control system used to improve the behavior of a multistorey structure under strong earthquakes. The structure and application of supplemental controlled stiffness devices (CSD) are discussed. Instantaneous optimal control is used to obtain the control forces at each time step during an earthquake according to the predicted values of the displacements and the velocities of each storey. A linear autoregressive model with exogenous input (ARX) is used to predict the displacements and the velocities of the frame in order to overcome the time delay problem in the control system. Control of the forces developed in the CSD is possible, owing to the mechanical structure of the device. This device can be efficiently used as a controller because the forces developed in it are independent of the structure's displacements or velocities. Its efficiency is demonstrated in a numerical simulation of a seven‐storey building. The simulation shows that the behavior of a structure with the proposed predictive control system is significantly improved compared with that of an uncontrolled structure subjected to the same earthquakes. In this example, the displacements and velocities in the structure were predicted according to an ‘occurring’ earthquake by the ARX model and were used to obtain the optimal control forces (predictive control). These forces yielded a response of the structure with CSD that was similar to the response obtained with control forces, which were calculated from a ‘known’ complete history of the earthquake displacement and velocity values (instantaneous optimal control). Copyright © 2003 John Wiley & Sons, Ltd.
The state‐of‐the‐art of damage detection by vibration monitoring: the SIMCES experience
Authors: Roeck Guido De
Published: June 2003

A major contribution to the status of vibration monitoring has been delivered by the European Brite EuRam research project BE‐3157, System Identification to Monitor Civil Engineering Structures (SIMCES). This paper gives a brief description of the project, the tests performed on bridge Z24 and the results obtained from these tests. The need for further research is indicated. Copyright © 2003 John Wiley & Sons, Ltd.
Sensors and systems for structural health monitoring
Authors: Van der Auweraer Herman , Peeters Bart
Published: June 2003

This paper reviews the subject of structural damage detection from the point of view of instrumentation. The focus is on the measurement and interpretation of structural variables such as vibration, displacement and curvature. Some major approaches in the area of civil engineering and aeronautics are presented. Especially the corresponding sensor and data collection solutions are discussed as well as the key technologies for relating variations in the measured parameters to damage. Copyright © 2003 John Wiley & Sons, Ltd.
Large amplitude free vibrations of beams – an energy approach
Authors: Rao G.V. , Raju K.K.
Published: June 2003

The conservation of energy principle, which says that the total energy of a vibrating system, at any given instant of time is constant, is used to evaluate the large amplitude free vibration behaviour of beams with immovable ends. With an assumed space mode, which satisfies the geometric boundary conditions, the final governing equation is obtained. This equation is solved by a numerical integration scheme to obtain the ratio of frequencies of nonlinear to linear systems. Comparison of the present results with those of other researchers on this topic and a Galerkin approximation is also included.
Stochastic structural topology optimization: existence of solutions and sensitivity analyses
Authors: Evgrafov A. , Patriksson M. , Petersson J.
Published: June 2003

We consider structural topology optimization problems including unilateral constraints arising from, for example, non‐penetration conditions in contact mechanics or non‐compression conditions for elastic ropes. To construct more realistic models and to hedge off possible failures or an inefficient behaviour of optimal structures, we allow parameters (for example, loads) defining the problem to be stochastic. The resulting nonsmooth stochastic optimization problem is an instance of stochastic mathematical programs with equilibrium constraints (SMPEC), or stochastic bilevel programs. The existence as well as the continuity of optimal solutions with respect to the lower bounds on the design variables are established. The question of continuity of the optimal solutions with respect to small changes in the probability measure is analysed. For a subclass of the problems considered the answer is affirmative, thus establishing the robustness of optimal solutions.
Weighted Lp estimates of solutions to boundary value problems for second order elliptic systems in polyhedral domains
Authors: Maz'ya V.G. , Roßmann J.
Published: June 2003

In this paper we are concerned with boundary value problems for general second order elliptic equations and systems in a polyhedral domain. We consider solutions in weighted Lp Sobolev spaces. A special section is dedicated to weak solutions. We prove solvability theorems and regularity assertions for the solutions.
Approximation theory methods for solving elliptic eigenvalue problems
Authors: Still G.
Published: June 2003

Eigenvalue problems with elliptic operators L on a domain G ⊂ R2 are considered. By applying results from complex approximation theory we obtain results on the approximation properties of special classes of solutions of Lu = 0 on G . These solutions are used as trial functions in a method for solving the eigenvalue problem which is based on a‐posteriori error bounds. Singular trial functions are applied to smooth the problem at corner points of G . In special situations, this method can produce approximations of eigenvalues and eigenfunctions with extremely high accuracy by only using a low number of trial functions. Some illustrative numerical examples for the eigenvalue problem with the Laplacian are presented. We discuss two problems from plasma physics (‘relaxed plasma’, ‘MHD‐equation’).
Modulation of Cav3.2 T‐type Ca2+ channels by protein kinase C
Authors: Park Jin-Yong , Jeong Seong-Woo , Perez-Reyes Edward , Lee Jung-Ha
Published: June 2003

Although T‐type Ca2+ channels have been implicated in numerous physiological functions, their regulations by protein kinases have been obscured by conflicting reports. We investigated the effects of protein kinase C (PKC) on Cav3.2 T‐type channels reconstituted in Xenopus oocytes. Phorbol‐12‐myristate‐13‐acetate (PMA) strongly enhanced the amplitude of Cav3.2 channel currents (∼3‐fold). The augmentation effects were not mimicked by 4α‐PMA, an inactive stereoisomer of PMA, and abolished by preincubation with PKC inhibitors. Our findings suggest that PMA upregulates Cav3.2 channel activity via activation of oocyte PKC.
Environmental stresses inhibit and stimulate different protein import pathways in plant mitochondria
Authors: Taylor Nicolas L. , Rudhe Charlotta , Hulett Joanne M. , Lithgow Trevor , Glaser Elzbieta , Day David A. , Millar A.Harvey , Whelan James
Published: June 2003

The impact of various environmental stresses (drought, chilling or herbicide treatment) on the capacity of plant mitochondria to import precursor proteins was investigated. Drought treatment stimulated import and processing of various precursor proteins via the general import pathway. The stimulatory effect of drought on the general import pathway was due to an increased rate of import, was accompanied by an increased rate of processing, and could be attributed to the presequence of the precursor protein. Interestingly, drought decreased the import of the FAd subunit of ATP synthase suggesting a bypass of the point of stimulation during import of this precursor. Both chilling and herbicide treatment of plants, on the other hand, caused inhibition of import with all precursors tested. No decrease in processing of imported proteins was observed by these stress treatments. Western analysis of several mitochondrial proteins indicated that the steady‐state level of several mitochondrial components, including the TOM20 receptor and the core subunits of the cytochromebc1complex responsible for processing, remained largely unchanged. Thus environmental stresses differentially affect import of precursor proteins in a complicated manner dependent on the import pathway utilised.
Weighting of acoustic- and trawl-survey indices for the assessment of North Sea herring
Authors: Simmonds E.J
Published: June 2003

Acoustic surveys are used in 20 stock assessments within the ICES community, and almost all as relative indices of abundance, but little has been done to explore their performance in detail. The North Sea herring acoustic survey started in 1979 and by 1984 had become an internationally-coordinated survey conducted annually in July. Along with trawl- and larvae-survey indices, it has been used to tune a catch-at-age assessment model of North Sea herring. In this article, the precision of the survey is estimated, using data at ICES statistical-rectangle level from 1989 to 2001, and bootstrap-resampling methods modified by geostatistical estimates of the spatial autocorrelation. Similar techniques are applied to the larvae, Methot and trawl surveys that provide the other data on the distribution and abundance of North Sea herring. The comparison of survey performance is also examined using the bootstrap estimates of abundance to give 1000 simulated assessments of North Sea herring using the integrated catch-at-age (ICA) method. The results of these analyses are compared and the annual acoustic survey is shown to provide the most precise estimate of relative abundance for adult North Sea herring each year. The weighting of the various indices within the assessment is investigated. A weighting method is presented that provides a more precise method for estimating the stock. The more precise assessments are compared for retrospective pattern. An assessment is proposed which provides the most precise stock estimates with the best retrospective pattern. This assessment has been reviewed and accepted by the ICES Advisory Committee on Fisheries Management. The importance of the acoustic survey and its contribution to the assessment in relation to the other indices is discussed.
Using the Violence Prevention Community Meeting Protocol
Authors: Lanza Marilyn Lewis , Kazis Lewis , Lee Austin
Published: June 2003

Assaultive behavior is a serious problem in health care. Nurses, nursing assistants, and other patients increasingly are becoming targets for patient assault. Costs of assaults are high, both in terms of dollars spent and clinical repercussions such as staff injury and lowered morale. This article describes the development of a protocol, in the form of clinical practice guidelines, for a community meeting to decrease assaultive behavior. Implications include use of the guidelines and the need to conduct either a before-and-after study or a comparison of one unit using the intervention with one not using it. There are also questions identified for further study that would test the broad effectiveness of the Violence Prevention Community Meeting guidelines.
Promoting Quality of Life for Clients Diagnosed with Dementia
Authors: Hendry Karen C. , Douglas Dianna H.
Published: June 2003

Much of the nursing research related to clients diagnosed with dementia has focused on management of disruptive behaviors, safety, and basic sustenance with little attention to the higher level developmental needs of love, belonging, self-esteem, self-actualization, and aesthetics. As nurses seek to understand the links between cognitive, functional, and developmental decline and focus interventions on meeting the higher level needs of their clients, they can provide more comprehensive care and promote quality of life for clients diagnosed with dementia.
Depression in Women’s Magazines
Authors: Borman Jan
Published: June 2003

BACKGROUND: Mass communication research suggests that the media influence both what a population thinks about and how it thinks about an event or situation by controlling what is covered and how topics are framed. One medium, popular women’s magazines, has published depression-related articles for decades. However, little is known about the content and frame of these articles.

OBJECTIVE: The research sought to determine what women’s magazines published about depression between 1980 and 2000.

DESIGN: Articles published on depression in the top eight circulating women’s magazines, between 1980 to 1985 and 1995 to 2000 were retrieved and analyzed using qualitative media analysis methodology.

RESULTS: Between the two periods, the magazines increased the number of published articles on depression and increasingly framed it as a treatable but stigmatized illness.

CONCLUSION: Women’s magazines, which regularly publish information on depression, have high circulation rates, resulting in millions of exposures to their messages. Psychiatric nurse-authors have an opportunity to influence these messages.
Assessing and Treating Sexual Dysfunction
Authors: Mahan Vanita
Published: June 2003

This article seeks to heighten the awareness of nurses about sexual dysfunction. Although dealing with sexual dysfunction issues might be sensitive, nurses can discuss the subject and elicit important information from patients by following simple rules and careful questioning. Classifications of sexual dysfunctions and the causes and treatment for each are described.
Emergency Nurses’ Responses to a Survey about Means Restriction: An Adolescent Suicide Prevention Strategy
Authors: Grossman Janet , Dontes Arnim , Kruesi Markus J.P. , Pennington James , Fendrich Michael
Published: June 2003

BACKGROUND: Little is known about nurses’ knowledge and practice of an injury control strategy (means restriction) with parents of adolescents at risk for suicide who are cared for in the emergency department.

OBJECTIVES: This study examined the experiences of emergency nurses (N = 527) with suicidal adolescents; their training, knowledge, practice, and attitudes toward means restriction; and unit practice related to the delivery of means restriction education to parents by emergency nurses.

DESIGN: A survey was mailed to all members of the Illinois Chapter of the Emergency Nurses Association.

RESULTS: Although the majority (80%, n = 407) of respondents had recent experience with suicidal adolescents, only 24% (n = 122) had ever received means restriction training, 28% (n = 136) provided means restriction education to parents, and 18% (n = 89) worked in units where means restriction is standard practice.

CONCLUSIONS: The findings of this study are consistent with injury control literature. The authors recommend training emergency department staff in means restriction, adopting a means restriction protocol for adolescents at risk for suicide, and conducting outcome studies to determine the effectiveness of training and practice.
Influence of dust and sulfate aerosols on ocean color spectra and chlorophyll a concentrations derived from SeaWiFS off the U.S. east coast
Authors: Schollaert Stephanie E. , Yoder James A. , O'Reilly John E. , Westphal Douglas L.
Published: June 2003

The influence of two dominant aerosol species on satellite ocean color retrievals is examined off the U.S. East Coast in the western Sargasso subtropical gyre. Waters of very low chlorophyll concentration have normalized water‐leaving radiance (nLw) spectra highest in blue and decreasing monotonically with increasing wavelength. For water with chlorophyll concentrations less than 0.13 mg m−3 we compared the Sea‐viewing Wide Field‐of‐view Sensor (SeaWiFS) nLw spectra for different aerosol conditions (clear, dust‐dominated, and sulfate‐dominated) over 1 year between March 1999 and March 2000. With appropriate atmospheric correction, satellite‐derived nLw spectra should be insensitive to the presence of atmospheric aerosols, but we found the SeaWiFS spectra to be sensitive to the species and optical thickness of aerosols. The SeaWiFS bio‐optical chlorophyll algorithms use nLw(λ)/nLw(555) band ratios (where λ = 443, 490, or 510 nm): any biases in the band ratios result in incorrect chlorophyll concentration estimates. When aerosols were negligible, nLw spectra were consistent with in situ reference data between 443 and 510 nm. With increasing aerosol optical thickness during dust events, most common during summer, the nLw spectra were lowered between 412 and 510 nm, decreasing nLw(λ)/nLw(555) band ratios and resulting in artificially high chlorophyll a estimates. Sulfate‐dominated pixels were associated with elevated nLw spectra between 412 and 555 nm. Increasing sulfate optical thickness corresponded to decreases of the bio‐optical band ratios because of the increase at 555 nm, which also biased the chlorophyll a estimates high. The effect of sulfate upon ocean color retrievals is more problematic than dust off the U.S. east coast because of the nearly constant presence of sulfate along with commonly colocated pollutant aerosols that confound atmospheric correction algorithms.
Survival of Archean cratonal lithosphere
Authors: Sleep Norman H.
Published: June 2003

I use thermal convection models to search for combinations of physical parameters that are compatible with the results of xenolith studies on the history and present thermal structure of cratonal lithosphere. The cratonal lithosphere above ∼180 km depth formed in the Archean and remained stable until recently sampled. The mantle adiabat cooled ∼150 K over this time. The temperature change across the rheologically active boundary layer at the lithospheric base is <300 K over a depth range of several tens of kilometers. Modern cratonal lithospheric thicknesses are relatively uniform, ∼225 km, much thicker than old oceanic lithosphere. Cratonal lithosphere is now in quasi‐steady state with conductive heat flow to the surface in balance with heat supplied to the base of the lithosphere by convection driven by local temperature contrasts within the rheologically active boundary layer. This heat flow and the lithosphere thickness changed little after the cratonal lithosphere stabilized. One possibility is that chemically buoyant lithosphere forms a conductive lid above the convecting normal mantle. To survive, the chemical lithosphere also needs to be more viscous than normal mantle. A reasonable situation has chemical lithosphere a factor of 20 more viscous than normal mantle with weakly temperature‐dependent viscosity (a factor of e over 100 K) from 0.2 × 1020 Pa s along the modern mantle adiabat. However, a chemical lid is unnecessary for lithospheric thickness to change slowly over time. For example, the base of the lithosphere may be stable if the viscosity at its base (along an adiabat) decreases rapidly with depth.
Reduced‐rank Kalman filters applied to an idealized model of the wind‐driven ocean circulation
Authors: Buehner Mark , Malanotte‐Rizzoli Paola
Published: June 2003

The goal of this study is to evaluate a specific type of reduced‐rank Kalman filter for application to realistic ocean models. Data assimilation experiments were performed using an idealized nonlinear model of the wind‐driven ocean circulation. Separate configurations of the model were employed that exhibit either a quasi‐periodic behavior on the decadal timescale or a statistically stationary behavior accompanied by a high level of mesoscale eddy activity. The model consists of about 104 prognostic variables with observations of the model state taken at 30 locations concentrated in the region of highest variability near the western boundary. The assimilation scheme is an approximation to the extended Kalman filter in which the error covariances and corrections to the forecasts are only calculated in a reduced‐dimension subspace spanned by a small number of empirical orthogonal functions. The filter was implemented using both temporally evolving and stationary error covariances. Additionally for the quasi‐periodic model configuration, the model state space was partitioned according to three distinct flow regimes exhibited by the model and the asymptotically stationary error covariances calculated for each regime. The importance of specifying appropriate model and observation error covariances and the difficulties related to using stationary basis functions are also discussed. The performance of these reduced‐rank approaches is compared with the more traditional approach of using stationary error covariances with a simple prescribed functional form. The results show that the reduced‐rank Kalman filter is able to reduce the error in all assimilation experiments and consistently performs better than using simple prescribed error covariances for the quasi‐periodic case. Also, the performance of the filter with stationary error covariances is surprisingly similar to the much more computationally expensive filter with flow‐dependent covariances. The forecast errors from the assimilation experiments are examined with respect to their consistency with the error statistics calculated by the filter and their projections onto the resolved and unresolved subspaces.
Trans‐hemispheric contribution of C2–C10α, ω‐dicarboxylic acids, and related polar compounds to water‐soluble organic carbon in the western Pacific aerosols in relation to photochemical oxidation reactions
Authors: Sempéré Richard , Kawamura Kimitaka
Published: June 2003

Marine aerosol samples were collected during a western Pacific cruise covering the latitude range between 35°N and 40°S (140°E–180°E). They were analyzed for total carbon (TC), total nitrogen (TN), water‐soluble organic carbon (WSOC) along with the molecular distributions of C2–C10α, ω‐dicarboxylic acids, and related polar compounds, mainly, ω‐oxocarboxylic acids (C2–C9) and α‐dicarbonyls (C2–C3). Oxalic acid (C2) was the most abundant followed by malonic (C3) and succinic (C4) acids. The total diacid concentration range was 7–605 ng m−3(av. 85 ng m−3) and the diacid‐carbon accounted for 2–15% (average 8%) of WSOC which comprised 29–55% (average 40%) of TC. Dry depositions of total diacids over the northern and southern Pacific Ocean were estimated to be 256–1907 μg m−2yr−1(average 735; n = 4) and 22–396 μg m−2yr−1(average 134; n = 14), respectively, whereas the air‐to‐sea flux of oxalic acid was 18–1351 μg m−2yr−1(average 466 μg m−2yr−1) and 7.5–275 μg m−2yr−1(average 75 μg m−2yr−1) in the Northern and Southern Hemispheres. We observed that the concentration ratios of diacid‐C/WSOC, azelaic acid (C9)/ω‐oxononanoic acid, maleic acid (iC4cis)/fumaric (iC4trans) acid and succinic acid (C4)/total diacids were correlated with air temperature. These findings showed that the intensity of photochemical oxidation reactions and thus the variation in sunlight intensity characterized here by air temperature, significantly control the molecular distribution of water‐soluble organic compounds during the long‐range transport of anthropogenic and/or biogenic higher molecular weight organic compounds.
Evolution of pickup proton spectra in the inner heliosheath and their diagnostics by energetic neutral atom fluxes
Authors: Chalov Sergei V. , Fahr Hans J. , Izmodenov Vladislav V.
Published: June 2003

The spatial evolution of pickup protons moving from the termination shock outward to the heliopause, after having suffered stochastic preacceleration in the supersonic solar wind, is studied taking into account ongoing velocity diffusion of the protons in the turbulent Alfvénic fluctuation field. Here only the upwind part of the heliosheath is considered. It is shown that spectra of pickup protons in the inner heliosheath are substantially different from those in the region inside the termination shock. Differential fluxes of energetic neutral atoms originating from pickup protons by charge exchange with interstellar hydrogen atoms in the inner heliosheath and arriving at 1 AU are calculated. It is shown that observations of energetic neutral hydrogen fluxes in a sufficiently wide energy range can be used to place strong limits on the level of solar wind turbulence near the termination shock and further downstream.
Longevity and stability of cratonic lithosphere: Insights from numerical simulations of coupled mantle convection and continental tectonics
Authors: Lenardic A. , Moresi L.‐N. , Mühlhaus H.
Published: June 2003

The physical conditions required to provide for the tectonic stability of cratonic crust and for the relative longevity of deep cratonic lithosphere within a dynamic, convecting mantle are explored through a suite of numerical simulations. The simulations allow chemically distinct continents to reside within the upper thermal boundary layer of a thermally convecting mantle layer. A rheologic formulation, which models both brittle and ductile behavior, is incorporated to allow for plate‐like behavior and the associated subduction of oceanic lithosphere. Several mechanisms that may stabilize cratons are considered. The two most often invoked mechanisms, chemical buoyancy and/or high viscosity of cratonic root material, are found to be relatively ineffective if cratons come into contact with subduction zones. High root viscosity can provide for stability and longevity but only within a thick root limit in which the thickness of chemically distinct, high‐viscosity cratonic lithosphere exceeds the thickness of old oceanic lithosphere by at least a factor of 2. This end‐member implies a very thick mechanical lithosphere for cratons. A high brittle yield stress for cratonic lithosphere as a whole, relative to oceanic lithosphere, is found to be an effective and robust means for providing stability and lithospheric longevity. This mode does not require exceedingly deep strength within cratons. A high yield stress for only the crustal or mantle component of the cratonic lithosphere is found to be less effective as detachment zones can then form at the crust‐mantle interface which decreases the longevity potential of cratonic roots. The degree of yield stress variations between cratonic and oceanic lithosphere required for stability and longevity can be decreased if cratons are bordered by continental lithosphere that has a relatively low yield stress, i.e., mobile belts. Simulations that combine all the mechanisms can lead to crustal stability and deep root longevity for model cratons over several mantle overturn times, but the dominant stabilizing factor remains a relatively high brittle yield stress for cratonic lithosphere.
Near‐surface dynamical structure of the Kuroshio Extension
Authors: Niiler P. P. , Maximenko N. A. , Panteleev G. G. , Yamagata T. , Olson D. B.
Published: June 2003

Lagrangian data from 657 SVP drifters, CNES/Aviso (Archiving, Validation, and Interpretation of Satellite Oceanographic data) time variable satellite altimeter sea level anomaly and Levitus 98 hydrographic data are used to develop 0.25° spatial resolution maps of the mean and eddy circulations in the northwestern Pacific during the 1990s. Drifter velocities at 15 m depth and 200 m temperature data clearly indicate in the Kuroshio Extension (KE) jet two prominent meanders that culminate in a 300 km northward deflection east of the Shatsky Rise at 160°E. The interannual trends of Aviso mesoscale variance are absent along the path of the meandering KE jet. Three anticyclonic recirculations can be identified south or southeast of the Kuroshio, the southernmost around Daito Island being a new discovery. About 3% of the drifters with drogues attached crossed the Kuroshio front. The Aviso currents are correlated at 0.8 with drifter geostrophic velocity. The Aviso geostrophic currents are adjusted in amplitude to the contemporaneous drifter observations and are further used to compute an unbiased mean geostrophic circulation and the quasi‐geostrophic Reynolds' stresses in the KE region. The principal axes of the eddy Reynolds' stresses are oriented along the unbiased mean velocity vectors within the meandering KE jet. The time‐mean horizontal momentum balance that includes both the mean and eddy momentum convergences is used to compute absolute sea level map and its uncertainty. At 145°E the 2000 m depth absolute dynamic height referenced to the sea level reveals a heretofore unknown 70 dynamic cm drop from 25° to 42°N.
Comparison of future climate change over North America simulated by two regional models
Authors: Chen M. , Pollard D. , Barron E. J.
Published: June 2003

Climate versions of the Pennsylvania State University/National Center for Atmospheric Research (NCAR) MM5 and of the International Centre for Theoretical Physics/NCAR RegCM2 are intercompared with two 10‐year simulations over North America for present (1990–1999) and close to doubled CO2 (2090–2099), driven by the same general circulation model forcing from a 100‐year transient run of the NCAR Climate System Model. Some model options and modules are identical in MM5 and RegCM2, including radiation and the entire land surface model. MM5 and RegCM2 agree in their general patterns of surface temperatures. Details related to mesoscale effects are well represented in both models. Precipitation is more consistent in MM5 and RegCM2 in winter than in summer. Differences in temperature and precipitation between MM5 and RegCM2 are small in winter due to the strong large‐scale forcing but are large in summer because of the increasingly important contribution of local processes. Despite the general agreement between MM5 and RegCM2, significant differences exist over some areas due to the regional models' internal atmospheric physics and dynamics. The magnitude of these differences is large enough in some areas to cause serious uncertainties in any potential assessment of societal impacts of regional climate change.
Saharan dust over a central European EARLINET‐AERONET site: Combined observations with Raman lidar and Sun photometer
Authors: Müller Detlef , Mattis Ina , Wandinger Ulla , Ansmann Albert , Althausen Dietrich , Dubovik Oleg , Eckhardt Sabine , Stohl Andreas
Published: June 2003

Combined observations with an advanced aerosol water‐vapor temperature Raman lidar and a Sun photometer are used for a detailed characterization of geometrical and optical properties of a continental‐scale Saharan dust event observed over Leipzig (51.3°N, 12.4°E), Germany, from 13 to 15 October 2001. The Raman lidar is part of the European Aerosol Research Lidar Network (EARLINET). Automatic observations of aerosol optical depth and sky brightness are made with the Sun photometer in the framework of the worldwide operating Aerosol Robotic Network (AERONET). The dust plume reached a top height of 6000 m. Sun photometer and lidar observations showed a constant increase of columnar optical depth at 532 nm from 0.25 on 13 October 2001 to a maximum of ∼0.63 on 14 October 2001. According to observations with lidar, up to 90% of the optical depth at the wavelength of 532 nm was contributed by the dust layer above 1000‐m height. Ångström exponents from Sun photometer observations between 380 and 1020 nm were ∼0.45 at the beginning of the dust period, and dropped to minimum values of 0.14 during the peak of the dust outbreak. Vertically resolved Ångström exponents derived from lidar profiles of the extinction coefficients at 355 and 532 nm showed a strong variability with values as low as −0.2 in the center of the dust plume. Below 1000‐m height column‐averaged Ångström exponents strongly varied between 1.0 in the beginning of the dust period and 0.39 on 14 October 2001 when the dust penetrated into the boundary layer. Comparison of column‐averaged optical depth and Ångström exponents derived from lidar and Sun photometer observations showed excellent agreement. Particle depolarization ratios of up to 25% were derived from lidar observations at 532 nm. Scattering phase functions retrieved from Sun photometer observations indicated particles of nonspherical shape. This shape caused unusually large particle extinction‐to‐backscatter (lidar) ratios at 532 nm in the range from 50 to 80 sr. There were substantial deviations of the lidar ratio at 532 nm derived from both measurement methods. They are explained by the effect of particle shape.
Coccolith Sr/Ca records of productivity during the Paleocene‐Eocene thermal maximum from the Weddell Sea
Authors: Stoll Heather M. , Bains Santo
Published: June 2003

A major perturbation of the global carbon cycle ∼55 million years ago, believed to result from release of 1000–2000 Gt of C from methane hydrates, correlates with an intense but transient greenhouse warming event known as the Paleocene Eocene Thermal Maximum (PETM). The rapid (105 years) recovery of global temperatures reflects important negative feedbacks in the climate system and carbon cycle. Enhanced marine productivity may be one important feedback, but indicators for productivity changes have yielded conflicting results. Here we use a new independent indicator, Sr/Ca in coccolith carbonate, which covaries with the productivity of coccolithophorid algae, to investigate the biotic response in the most complete PETM deep sea record which was recovered at ODP Site 690 in the Weddell Sea. In the dominant coccolithophorid genus Toweius a large (40%) Sr/Ca increase immediately after the gas hydrate release signals a dramatic productivity increase. Productivity levels remained high for 60,000 years but decreased to pre‐event levels by 120,000 years after the gas hydrate release. Productivity levels during the PETM are higher than observed at any other time in our ∼400,000 year record. Other coccolithophorid genera Chiasmolithus and Discoaster show a brief modest (25% Sr/Ca increase) increase in productivity that lags behind the methane event by 50,000 years and is within the range of productivity variation elsewhere in the record. The timing of the Toweius productivity increase agrees well with Os isotope records of globally increased weathering intensity, which may have provided higher nutrient fluxes to stimulate algal productivity. If this type of productivity response occurred globally, it would also be consistent with the timing of C drawdown that may have returned temperatures to near pre‐event levels.
A coordinated ground‐based and IMAGE satellite study of quiet‐time plasmaspheric density profiles
Authors: Dent Zoë C. , Mann I. R. , Menk F. W. , Goldstein J. , Wilford C. R. , Clilverd M. A. , Ozeke L. G.
Published: June 2003

Cold plasma mass density profiles in the plasmasphere have been determined for the geomagnetically quiet day of 19th August 2000 using the cross‐phase technique applied to ground‐based magnetometer data from the SAMNET, IMAGE and BGS magnetometer arrays. Cross‐phase derived mass densities have been compared to electron densities derived from both ground‐based VLF receiver measurements, and the IMAGE satellite RPI. The cross‐phase results are in excellent agreement with both the VLF and IMAGE observational results, thus validating the cross‐phase technique during quiet times. This is the first such coordinated multi‐instrument study, and has enabled very few heavy ions to be inferred in the plasmasphere for L > 3.45 on this day. The observational results were compared to plasma mass densities from the SUPIM model and were found to be in excellent agreement. IMAGE EUV data also verified the existence of azimuthal structure in the outer quiet‐time plasmasphere.
Unusual stratospheric transport and mixing during the 2002 Antarctic winter
Authors: Allen Douglas R. , Bevilacqua Richard M. , Nedoluha Gerald E. , Randall Cora E. , Manney Gloria L.
Published: June 2003

Unusually large planetary wave activity in the 2002 Antarctic winter stratosphere weakened and warmed the polar vortex. Three minor warmings during August and early September preceded a late‐September major warming when the middle stratospheric zonal winds reversed to easterly and the polar temperature increased by an additional 25 K. Polar Ozone and Aerosol Measurement (POAM III) ozone data at high southern latitudes show unusually large variability in 2002 compared to previous POAM III years (1998–2001). Analyses of air parcel transport indicate this variability is caused by large‐scale isentropic transport. Diagnostics of transport and mixing show that during the major warming the lower stratospheric vortex remained intact, while the middle stratospheric vortex split into two pieces; one piece rapidly mixed with extravortex air, while the other returned to the pole as a much weaker and smaller vortex.
Origin of the polygons and the thickness of Vastitas Borealis Formation in Western Utopia Planitia on Mars
Authors: Yoshikawa Kenji
Published: June 2003

Many middle scale (about 100m cracking space) polygons are located between the area of the giant polygons and the thumbprint terrains in Western Utopia Planitia. Most of the patterns are located on Vastitas Borealis Formation. The polygonal patterns have frequently been associated with collapsed features, such as a covered trough like features(the width of the underground crack is approximately 400–500 m). The thickness of the surface materials (6–12 m), where polygonal patterns occur, was calculated based on the space of cracking relationship. Polygonal networks with strongly oriented features and parallel to the contour line are likely caused by structural (geological) origin as well as bending forces from the center of the basin.
Trends in snow water equivalent in the Pacific Northwest and their climatic causes
Authors: Mote Philip W.
Published: June 2003

Observations of snow water equivalent (SWE) in the Pacific Northwest are examined and compared with variability and trends in temperature and precipitation at nearby climate stations. At most locations, especially below about 1800 m, substantial declines in SWE coincide with significant increases in temperature, and occur in spite of increases in precipitation.
10Be record and magnetostratigraphy of a Miocene section from Lake Baikal: Re‐examination of the age model and its implication for climatic changes in continental Asia
Authors: Horiuchi Kazuho , Matsuzaki Hiroyuki , Kobayashi Koichi , Goldberg Evgeny L. , Shibata Yasuyuki
Published: June 2003

We determined the concentration of the cosmogenic radionuclide 10Be in the Miocene section of a sediment core (5–12 My BP) retrieved from Lake Baikal (BDP98‐hole2) that had been previously dated by the magneto‐stratigraphic (MS) method. Using our new 10Be geochronology we reexamined the MS age‐depth assignments and found inconsistencies. We therefore reexamined the MS record and propose a new model which is consistent with the 10Be data, with an age of 8.4 My BP at a depth of 600 meters. Accepting the revised MS ages, we found the profile of the decay‐corrected 10Be concentration, which shows ca. 50% decreases of 10Be during the periods 0–2.7 My BP and 5.3–5.8 My BP. We also detected considerable increases of the 10Be flux into sediments before 4.5 My BP.
Influence of 1‐aminocyclohexane‐1‐carboxylic acid in position 2 or 3 of AVP and its analogues on their pharmacological properties
Authors: Jastrzȩbska B. , Derdowska I. , Kowalczyk W. , Machova A. , Slaninová J. , Lammek B.
Published: June 2003

Abstract: In this study we describe the synthesis and some pharmacological properties of seven new analogues of arginine vasopressin (AVP) substituted in position 2 or 3 with 1‐aminocyclohexane‐1‐carboxylic acid (Acc). All peptides were tested for the pressor, antidiuretic and uterotonic in vitro activities. The Acc3 modifications of AVP, dAVP, [d‐Arg8]VP and [Cpa1]AVP have been found to be deleterious for interaction with all three neurohypophyseal hormone receptors, as judged from the several orders of magnitude decreased biological activities, whereas Acc2 substitution selectively altered the interaction with the receptors. Two of the new analogues, [Acc2]AVP and [Acc2, d‐Arg8]AVP, are potent antidiuretic agonists. [Acc2]AVP exhibits moderate pressor agonistic activity and weak antiuterotonic properties. [Acc2, d‐Arg8]AVP has been found to be a weak antagonist in the pressor and uterotonic tests. Another analogue – [Cpa1, Acc3]AVP – turned out to be a highly selective V2 agonist. This is an unexpected effect, as its parent peptide, [Cpa1]AVP is a very potent V1a receptor antagonist. This is the first Cpa1 modification to have resulted in V2 agonism enhancement. Besides providing useful information about structure–activity relationships, our results could open up new possibilities in the design of highly potent and selective V2 agonists.
Design of peptides with branched β‐carbon dehydro‐residues: syntheses, crystal structures and molecular conformations of two peptides, (I) N‐Carbobenzoxy‐ΔVal‐Ala‐Leu‐OCH3 and (II) N‐Carbobenzoxy‐ΔIle‐Ala‐Leu‐OCH3
Authors: Vijayaraghavan R. , Kumar P. , Dey S. , Singh T.P.
Published: June 2003

Abstract: Highly specific structures can be designed by inserting dehydro‐residues into peptide sequences. The conformational preferences of branched β‐carbon residues are known to be different from other residues. As an implication it was expected that the branched β‐carbon dehydro‐residues would also induce different conformations when substituted in peptides. So far, the design of peptides with branched β‐carbon dehydro‐residues at (i + 1) position has not been reported. It may be recalled that the nonbranched β‐carbon residues induced β‐turn II conformation when placed at (i + 2) position while branched β‐carbon residues induced β‐turn III conformation. However, the conformation of a peptide with a nonbranched β‐carbon residue when placed at (i + 1) position was not found to be unique as it depended on the stereochemical nature of its neighbouring residues. Therefore, in order to induce predictably unique structures with dehydro‐residues at (i + 1) position, we have introduced branched β‐carbon dehydro‐residues instead of nonbranched β‐carbon residues and synthesized two peptides: (I) N‐Carbobenzoxy‐ΔVal‐Ala‐Leu‐OCH3 and (II) N‐Carbobenzoxy‐ΔIle‐Ala‐Leu‐OCH3 with ΔVal and ΔIle, respectively. The crystal structures of peptides (I) and (II) have been determined and refined to R‐factors of 0.065 and 0.063, respectively. The structures of both peptides were essentially similar. Both peptides adopted type II β‐turn conformations with torsion angles; (I): φ1 = −38.7 (4)°, ψ1 = 126.0 (3)°; φ2 = 91.6 (3)°, ψ2 = −9.5 (4)° and (II): φ1 = −37.0 (6)°, ψ1 = 123.6 (4)°, φ2 = 93.4 (4), ψ2 = −11.0(4)° respectively. Both peptide structures were stabilized by intramolecular 4→1 hydrogen bonds. The molecular packing in both crystal structures were stabilized in each by two identical hydrogen bonds N1…O1′ (−x, y + 1/2, −z) and N2…O2′ (−x + 1, y + 1/2, −z) and van der Waals interactions.