bluuebunny/crossref_metadata_2025 huggingface dataset:
In‐process Control of Design Inspection Effectiveness
Authors: Raz Tzvi , Barad Miryam
Published: February 2004

We present a methodology for the in‐process control of design inspection focusing on escaped defects. The methodology estimates the defect escape probability at each phase in the process using the information available at the beginning of a particular phase. The development of the models is illustrated by a case involving data collected from the design inspections of software components. The data include the size of the product component, as well as the time invested in preparing for the inspection and actually carrying it out. After smoothing the original data with a clustering algorithm, to compensate for its excessive variability, a series of regression models exhibiting increasingly better fits to the data as more information becomes available was obtained. We discuss how management can use such models to reduce escape risk as the inspection process evolves. Copyright © 2003 John Wiley & Sons, Ltd.
Some Modifications of the Classical Pre‐control Technique
Authors: San Matías Susana , Jabaloyes José , Carrión Andrés
Published: February 2004

Pre‐control is a simple technique for the initial evaluations of the capability of a process. It can be seen as a tool to get the set‐up approval or fulfilment of the specifications of a production process. As the resultant information of pre‐control should be used to adjust the process, it can be understood as a form of feedback controller. It has sometimes been considered as an alternative to statistical control charts for monitoring processes, although these tools differ in a number of ways. In this work, we propose some new alternatives to the classical pre‐control, particularly in its initial phase that aim to qualify the process, that is, to certify that it is capable. We present a comparative analysis of the power of the different alternatives. Copyright © 2003 John Wiley & Sons, Ltd.
Response Modeling Methodology Validating Evidence from Engineering and the Sciences
Authors: Shore Haim
Published: February 2004

Modeling a response in terms of the factors that affect it is often required in quality applications. While the normal scenario is commonly assumed in such modeling efforts, leading to the application of linear regression analysis, there are cases when the assumptions underlying this scenario are not valid and alternative approaches need to be pursued, like the normalization of the data or generalized linear modeling. Recently, a new response modeling methodology (RMM) has been introduced, which seems to be a natural generalization of various current scientific and engineering mainstream models, where a monotone convex (concave) relationship between the response and the affecting factor (or a linear combination of factors) may be assumed. The purpose of this paper is to provide the quality practitioner with a survey of these models and demonstrate how they can be derived as special cases of the new RMM. A major implication of this survey is that RMM can be considered a valid approach for quality engineering modeling and, thus, may be conveniently applied where theory‐based models are not available or the goodness‐of‐fit of current empirically‐derived models is unsatisfactory. A numerical example demonstrates the application of the new RMM to software reliability‐growth modeling. The behavior of the new model when the systematic variation vanishes (there is only random variation) is also briefly explored. Copyright © 2003 John Wiley & Sons, Ltd.
Robust Parameter Design: A Review
Authors: Robinson Timothy J. , Borror Connie M. , Myers Raymond H.
Published: February 2004

Parameter design is an engineering methodology intended as a cost‐effective approach for improving the quality of products and processes. The assumption is that there are both controllable factors (control variables) and uncontrollable/difficult to control factors (noise variables) that operate on the quality characteristic of a process. The goal of parameter design is to choose the levels of the control variables that optimize a defined quality characteristic while minimizing the variation imposed on the process via the noise variables. Parameter design was popularized in the mid 1980s by Japanese quality consultant Genichi Taguchi. A panel discussion edited by Nair summarized important responses to Taguchi's ideas and methodology. In the last decade, there have been many applications and new developments in this important area. This review paper focuses largely on the work done since 1992, but a historical perspective of parameter design is also given. Copyright © 2003 John Wiley & Sons, Ltd.
Dialysis‐linked complaints and burdens of illness on patient and spouse as predictors of survival in end‐stage renal disease patients with home hemodialysis: a 10‐year follow‐up study
Authors: Ekelund Marie‐Louise , Westman Kerstin , Andersson Sven Ingmar
Published: February 2004

Participants were 40 persons from a group of 44 end‐stage renal disease patients in southern Sweden who in 1985 received home hemodialysis under the auspices of a hospital renal unit, together with their spouses (n = 35). At a 10‐year follow‐up, 15 of the patients had died and 25 had survived. Univariate log rank tests of the influence of physical and demographic factors, the patient's dialysis‐linked complaints and the burdens of the illness indicated the most important predictors of 10‐year survival to be the patient's age, severity of the illness, the patient's dialysis‐linked complaints (notably that of itching), and the burdens of the patient's disease on the spouse (particularly burdens of a sexual character). Copyright © 2004 John Wiley & Sons, Ltd.
Nociceptive threshold can be changed by gravity stimulation in rats
Authors: Kawauchi Yasuko , Zeredo Jorge L. , Takeuchi Yoshinari , Kimoto Mari , Kumei Yasuhiro , Makita Koshi , Toda Kazuo
Published: February 2004

It has been reported that stress exposure could suppress pain in various animal species. However, very few studies have been performed on the effect of gravity stimulation on nociceptors. The aim of the present study is to reveal the effect of gravity stimulation on nociceptive withdrawal responses in rats. A von Frey type apparatus was used to evoke withdrawal reflexes at eight different body sites. Reflex thresholds were measured before and after gravity stimulation, which was applied with a centrifugal‐type apparatus at 116 r.p.m. (2 g), for 10 min. Naloxone‐HCl (0.1 mg kg−1 i.p.) was used before centrifugal stimulation to investigate whether the analgesic effect was mediated via endogenous opioids. The mean threshold values significantly increased in all body sites after 2.0 g exposure. Moreover, the analgesic effect was greater in upper body sites. The increase in threshold remained long after gravity stimulation, suggesting that humoral factors are involved in the analgesic mechanism. Gravity‐induced analgesia was antagonized by naloxone, indicating that an opioid system is included in its mediation. Copyright © 2004 John Wiley & Sons, Ltd.
Sleep quality and psychopathological features in obese binge eaters
Authors: Vardar Erdal , Caliyurt Okan , Arikan Ender , Tuglu Cengiz
Published: February 2004

The objectives of this study were to determine the prevalence of Binge Eating Disorder (BED) and to investigate the subjective sleep qualities and the psychopathological features of BED in treatment‐seeking obese patients. Thirty‐six treatment‐seeking obese subjects and 37 control subjects were interviewed with the DSM‐IV research criteria for BED, The Pittsburgh Sleep Quality Index (PSQI), Bulimic Investigatory Test, Edinburg (BITE) and SCL‐90‐R scales. Eight out of 36 treatment‐seeking obese patients (22.2 per cent) met the criteria for BED. The PSQI global scores, sleep latencies and SCL‐PSDI, SCL‐interpersonal sensitivity subscale results were all significantly higher in treatment‐seeking BED obese subjects than non‐BED (N‐BED) subjects and controls. Our findings suggest that BED appears to be a common disorder in treatment‐seeking obese patients. The treatment‐seeking obese BED patients suffer from more psychopathological problems than N‐BED obese patients and controls, and the subjective sleep qualities are likely to be disrupted in patients with BED. Copyright © 2004 John Wiley & Sons, Ltd.
Work locus of control and its relationship to health and job satisfaction from a gender perspective
Authors: Muhonen Tuija , Torkelson Eva
Published: February 2004

With its focus on gender, the aim of this study was to investigate the role of work locus of control (WLC) for job satisfaction and health in the context of occupational stress. Data were collected from 281 women and men at both managerial and non‐managerial level in a Swedish telecom company. As hypothesized, external WLC was positively related to stressors and symptoms of ill‐health, whereas it was negatively related to job satisfaction. These results applied for both women and men. Even though ANOVAs did not show a gender difference in WLC, the results of the hierarchical multiple regression analyses indicated that WLC was a significant predictor of both symptoms of ill‐health and job satisfaction, but only for women. Besides these main effects WLC also acted as a moderator in the stress–health relationship for women. This indicates that separate analyses for women and men are needed in order to investigate potential gender differences that might otherwise go unnoticed. Copyright © 2004 John Wiley & Sons, Ltd.
Social identity, social influence and reactions to potentially stressful tasks: support for the self‐categorization model of stress
Authors: Haslam S. Alexander , Jetten Jolanda , O'Brien Anne , Jacobs Elissa
Published: February 2004

An experiment was conducted to investigate the role that social influence plays in the appraisal of a potentially stressful situation. Participants (N = 40) preparing for a mental arithmetic task were exposed to a message in which the task was described as stressful or challenging. The message was delivered by the same person in each condition but this person was said to be either an ingroup member (a University student) or an outgroup member (a stress disorder sufferer). Consistent with predictions derived from self‐categorization theory, message source and message content interacted to determine the stress experienced while performing the task. Findings imply that the impact of informational support is not constant but varies systematically as a function of the group membership of the support provider. Implications for theory and practice are discussed with emphasis on the importance of social context as a determinant not only of what information people are exposed to about stress but also of how that information is construed. Copyright © 2004 John Wiley & Sons, Ltd.
Paradigms for pharmacologic use as a treatment component in feline behavioral medicine
Authors: Overall Karen L
Published: February 2004

Veterinary behavioral medicine remains an under-supported, under-appreciated, and under-taught specialty within veterinary medicine. Neuropsychopharmacology is the aspect that has provided the field with the most scientific legitimacy, but is also one of the most hotly debated. Paradigms for use of pharmacologic intervention include firstly ruling out any underlying medical cause. If a behavioral diagnosis can be made, treatment with psychotropic medication may be considered, although their use is most effective as part of an integrated treatment program that includes behavior modification. Used without an understanding of the mechanism of action, pharmacologic intervention may only blunt or mask behavior without altering processes or environments that produced the behavior. This paper reviews specific drugs, mechanism of action of those drugs, and relevant uses are reviewed for cats.

Future advances in treatment in veterinary behavioral medicine will be pharmacological and neurophysiological. As the field of veterinary behavioral medicine expands, its paradigm will enlarge to include routine combination therapy and the implementation of neuropharmacological intervention as a diagnostic tool.
Fractious cats and feline aggression
Authors: Beaver Bonnie V.
Published: February 2004

Despite variation in terminology it is clear that the context in which feline aggression occurs is important for classification, prevention and treatment. Many of the aggressions discussed can be considered variants of normal feline behavior, so client education is particularly important. Educated clients will know when their cat can benefit from veterinary intervention, and when closing a door may be sufficient. The goals of treating all feline aggressions should be safety for all concerned, and quality of their living environment for the cats. The greater our knowledge, the more likely we are to achieve these goals.
Social organization in the cat: A modern understanding
Authors: Crowell-Davis Sharon L. , Curtis Terry M. , Knowles Rebecca J.
Published: February 2004

An increasing body of research work has made it clear that, while Felis catus can survive in the solitary state, social groups with an internal structure, are formed whenever there are sufficient food resources to support them. Most people who have cats have two or more cats. Failure to understand what will promote either friendly or aggressive behavior can lead to various behavior problems, including aggression and conflict over resources, such as food, resting sites and litterboxes. An understanding of the natural social organization, relationships and communication between cats is therefore essential, and is the subject of this paper.
Mono‐unsaturated fatty acids protect against β‐cell apoptosis induced by saturated fatty acids, serum withdrawal or cytokine exposure
Authors: Welters Hannah J , Tadayyon Moh , Scarpello John H.B , Smith Stephen A , Morgan Noel G
Published: February 2004

Long‐chain saturated fatty acids are cytotoxic to pancreatic β‐cells while shorter‐chain saturated and long‐chain unsaturated molecules are better tolerated. Mono‐unsaturated fatty acids are not, however, inert since they inhibit the pro‐apoptotic effects of saturated molecules. In the present work we show that the mono‐unsaturates palmitoleate (C16:1) or oleate (C18:1) also cause marked inhibition of apoptosis induced by exposure of clonal BRIN‐BD11 β‐cells to serum withdrawal or a combination of interleukin‐1β plus interferon‐γ. This response was dose‐dependent and not accompanied by changes in NO formation. Taken together, the results suggest that mono‐unsaturated fatty acids regulate a distal step common to several apoptotic pathways in pancreatic β‐cells.
The electron conduction of photosynthetic protein complexes embedded in a membrane
Authors: Stamouli A. , Frenken J.W.M. , Oosterkamp T.H. , Cogdell R.J. , Aartsma T.J.
Published: February 2004

The conductivity of two photosynthetic protein–pigment complexes, a light harvesting 2 complex and a reaction center, was measured with an atomic force microscope capable of performing electrical measurements. Current–voltage measurements were performed on complexes embedded in their natural environment. Embedding the complexes in lipid bilayers made it possible to discuss the different conduction behaviors of the two complexes in light of their atomic structure.
Animal deoxyribonucleoside kinases: ‘forward’ and ‘retrograde’ evolution of their substrate specificity1
Authors: Piškur Jure , Sandrini Michael P.B , Knecht Wolfgang , Munch-Petersen Birgitte
Published: February 2004

Deoxyribonucleoside kinases, which catalyse the phosphorylation of deoxyribonucleosides, are present in several copies in most multicellular organisms and therefore represent an excellent model to study gene duplication and specialisation of the duplicated copies through partitioning of substrate specificity. Recent studies suggest that in the animal lineage one of the progenitor kinases, the so‐called dCK/dGK/TK2‐like gene, was duplicated prior to separation of the insect and mammalian lineages. Thereafter, insects lost all but one kinase, dNK (EC 2.7.1.145), which subsequently, through remodelling of a limited number of amino acid residues, gained a broad substrate specificity.
The equatorial anomaly: Its quantitative relation to equatorial bubbles, bottomside spread F, and E×B drift velocity during a month at solar maximum
Authors: Whalen James A.
Published: February 2004

The scintillation that is most disruptive to trans‐ionospheric RF propagation occurs when an equatorial bubble intersects the maximum electron density of the equatorial anomaly. This paper reports the first systematic observational study of the important interrelation between bubble and the anomaly together with the maximum pre‐reversal E × B drift velocity, and strong bottomside spread F (BSSF), which is a necessary condition for bubbles. An array of ionospheric sounders located near 75° W longitude measures latitudinal profiles of NmF2 at hourly intervals through 0°–40° dip latitude (DLAT) and 1800–0300 LT during a continuous period of 30 days at equinox and solar maximum. The anomaly is highly variable from day to day, but at 2100 LT, the time of its highest latitude, crest latitude and magnitude increase and decrease together, a relation that is linear above a threshold with coordinates of 38 × 105 el/cm3 and 15.4° DLAT. This threshold is important also because it corresponds to the maximum drift velocity of 50 m/s, and because above it nearly all bubbles are observed, directly as macroscopic bubbles and indirectly as strong BSSF. The importance to C/NOFS and other satellites is that maximum E × B drift, crest NmF2 and crest DLAT are in apparent one‐to‐one correspondence above this threshold, so that measurement of any one of the three implies measurement of the other two. Furthermore, any such measurement that exceeds the threshold indicates that bubbles can occur, whereas one that falls below the threshold indicates that they cannot.
Sunward polar cap convection
Authors: Jayachandran P. T. , MacDougall J. W.
Published: February 2004

This is a study of the conditions for which there is sunward convection in the central polar cap. The study of convection direction uses digital ionosonde measurements from two central polar cap stations (Resolute Bay, corrected geomagnetic (CG) latitude 83.3°N, and Eureka, CG latitude 88.67°N) and presents statistical results about pure sunward convection events. The sunward convection events in the central cap region are observed only when the interplanetary magnetic field (IMF) Bz is >2 nT. For weak northward IMF (<3 nT), sunward convection events are confined to the region near the noon cusp. For strong northward IMF conditions (>3 nT), sunward convection occurs at all local times, indicating the expansion of reverse convection to most of the central polar cap. There are very notable IMF By effects on the pattern of sunward convection. For IMF By positive the axis of the pattern of reverse convection appears to rotate toward the postnoon, whereas for IMF By negative the axis is rotated toward the prenoon. These axis orientations are compatible with the expected locations of lobe cell merging. Another significant IMF By effect is that the duration of sunward convection intervals when IMF By is negative is about the same as the duration of the northward IMF intervals, whereas for positive IMF By the sunward convection intervals usually last only for a short duration (∼1 hour). However, if the northward IMF interval is much longer than 1 hour, there is a sequence of these ∼l‐hour sunward convection events. The convection pattern during northward IMF appears to be compatible with a four‐cell form.
Direct velocity measurements in the Subantarctic Front and over Campbell Plateau, southeast of New Zealand
Authors: Stanton Basil R. , Morris Michele Y.
Published: February 2004

Flow variability in the Subantarctic Front (SAF) and over the Campbell Plateau, southeast of New Zealand, is examined using data from a current meter mooring array along with conductivity‐temperature‐depth (CTD) and satellite altimetry data. These data are part of an ongoing study of ocean climate variability in the region. Contrasting flow regimes were found with very energetic and highly variable flows in the SAF flowing along the Subantarctic Slope and much weaker flows over the Campbell Plateau. Currents up to 75 cm s−1 were observed in the core of the SAF, while flows over the plateau were typically less than 10 cm s−1. Estimates of the total bottom referenced transport from three CTD sections across the SAF varied between 48 and 68 Sv. Transports were also estimated using TOPEX/Poseidon altimetry sea truthed with the CTD data. The resulting 8‐year time series exhibited high variability resulting from current meanders and eddy activity. One event in the record appeared to be the result of a cyclonic eddy passing through the mooring array. This event was modeled using an idealized geostrophic eddy. The simulation reproduces the main features observed in the current meter records and the surface topography from the TOPEX/Poseidon altimeter. Inspection of the TOPEX/Poseidon data suggests that large cyclonic and anticyclonic eddies occur in the frontal region with a frequency of around 9 yr−1.
Morphodynamic modeling of an embayed beach under wave group forcing
Authors: Reniers A. J. H. M. , Roelvink J. A. , Thornton E. B.
Published: February 2004

The morphodynamic response of the nearshore zone of an embayed beach induced by wave groups is examined with a numerical model. The model utilizes the nonlinear shallow water equations to phase resolve the mean and infragravity motions in combination with an advection‐diffusion equation for the sediment transport. The sediment transport associated with the short‐wave asymmetry is accounted for by means of a time‐integrated contribution of the wave nonlinearity using stream function theory. The two‐dimensional (2‐D) computations consider wave group energy made up of directionally spread, short waves with a zero mean approach angle with respect to the shore normal, incident on an initially alongshore uniform barred beach. Prior to the 2‐D computations, the model is calibrated with prototype flume measurements of waves, currents, and bed level changes during erosive and accretive conditions. The most prominent feature of the 2‐D model computations is the development of an alongshore quasi‐periodic bathymetry of shoals cut by rip channels. Without directional spreading, the smallest alongshore separation of the rip channels is obtained, and the beach response is self‐organizing in nature. Introducing a small amount of directional spreading (less than 2°) results in a strong increase in the alongshore length scales as the beach response changes from self‐organizing to being quasi‐forced. A further increase in directional spreading leads again to smaller length scales. The hypothesized correlation between the observed rip spacing and wave group forced edge waves over the initially alongshore uniform bathymetry is not found. However, there is a correlation between the alongshore length scales of the wave group‐induced quasi‐steady flow circulations and the eventual alongshore spacing of the rip channels. This suggests that the scouring associated with the quasi‐steady flow induced by the initial wave groups triggers the development of rip channels via a positive feedback mechanism in which the small scour holes start attracting more and more discharge.
Field observations of shear waves in the surf zone
Authors: Noyes T. James , Guza R. T. , Elgar Steve , Herbers T. H. C.
Published: February 2004

Alongshore propagating meanders of the mean alongshore current in the surf zone called shear waves have periods of a few minutes and wavelengths of a few hundred meters. Here shear wave properties are estimated with arrays of current meters deployed for 4 months within 300 m of the shoreline of a sandy beach. Shear wave velocity fluctuations are approximately horizontally isotropic, with root mean square values between 10 and 40% of the mean (3‐hour‐averaged) alongshore current V. Cross‐shore variations of the time‐averaged shear wave momentum flux are consistent with shear wave energy generation close to shore where the breaking wave‐driven mean alongshore current V and current shear Vx are strong and with shear wave energy dissipation and transfer back to the mean flow farther offshore where V and Vx are weak. In case studies where V is a narrow jet near the shoreline the observed strong decay of shear wave energy levels seaward of the jet, and the cross‐shore and alongshore structure of shear waves within the jet, are similar to predictions based on the linearly unstable modes of the observed V. Shear wave energy levels also are high in a marginally unstable case with a strong, but weakly sheared, V.
Geophysical constraints on the deep structure of a limited ocean‐continent subduction zone at the North Iberian Margin
Authors: Ayarza P. , Martínez Catalán J. R. , Alvarez‐Marrón J. , Zeyen H. , Juhlin C.
Published: February 2004

Late Cretaceous to Cenozoic convergence between Iberia and Europe led to the partial closure of the Bay of Biscay with limited southward subduction of oceanic crust below the North Iberian Margin. Inclined sub‐Moho reflections and diffractions observed in deep seismic reflection profiles shot across the margin are especially well represented in two reflection profiles: ESCIN‐3.2 and ESCIN‐3.3. These two profiles have been chosen to test if the sub‐Moho reflections correspond to true primary deep events and, provided that they are reflecting off the subduction zone, to investigate its deep structure. Spectral analysis together with travel time estimation and migration allow us to characterize a number of these sub‐Moho events as deep‐source, low‐frequency (∼19 Hz), reflections and diffractions. Synthetic seismograms were generated by three‐dimensional seismic modeling of a sub‐Moho southward dipping surface, interpreted to correspond to the top of subducted oceanic crust. Comparison between the real and synthetic data show that inclined, low‐frequency sub‐Moho reflections in both, ESCIN‐3.2 and ESCIN‐3.3 profiles may correspond to reflections from southward subducted Bay of Biscay oceanic crust. Geoid, free‐air gravity, and absolute topography modeling provides additional constraints on the lithospheric‐scale structure of this limited ocean‐continent subduction zone beneath the North Iberian Margin.
Lateral slab deformation and the origin of the western Mediterranean arcs
Authors: Faccenna Claudio , Piromallo Claudia , Crespo‐Blanc Ana , Jolivet Laurent , Rossetti Federico
Published: February 2004

The western Mediterranean subduction zone (WMSZ) extends from the northern Apennine to southern Spain and turns around forming the narrow and tight Calabrian and Gibraltar Arcs. The evolution of the WMSZ is characterized by a first phase of orogenic wedging followed, from 30 Ma on, by trench retreat and back‐arc extension. Combining new and previous geological data, new tomographic images of the western Mediterranean mantle, and plate kinematics, we describe the evolution of the WMSZ during the last 35 Myr. Our reconstruction shows that the two arcs form by fragmentation of the 1500 km long WMSZ in small, narrow slabs. Once formed, these two narrow slabs retreat outward, producing back‐arc extension and large scale rotation of the flanks, shaping the arcs. The Gibraltar Arc first formed during the middle Miocene, while the Calabrian Arc formed later, during the late Miocene‐Pliocene. Despite the different paleogeographic settings, the mechanism of rupture and backward migration of the narrow slabs presents similarities on both sides of the western Mediterranean, suggesting that the slab deformation is also driven by lateral mantle flow that is particularly efficient in a restricted (upper mantle) style of mantle convection.
Hydrothermal circulation within topographically rough basaltic basement on the Juan de Fuca Ridge flank
Authors: Spinelli G. A. , Fisher A. T.
Published: February 2004

We use coupled heat and mass transport models to investigate the basement permeability distribution and hydrothermal circulation patterns in an area with large basement relief below flat seafloor on the eastern flank of the Juan de Fuca Ridge. If heat transport around Ocean Drilling Program Sites 1026 and 1027 were purely conductive, the top of basement at Site 1027 (below ∼600 m of sediment) would be ∼50°C warmer than at Site 1026 (below ∼250 m of sediment), but the top of basement in this area is nearly isothermal. Vigorous fluid circulation in hydrothermal (uppermost) basement is required in order to maintain a near isothermal sediment‐basement contact. We estimate the magnitude of hydrothermal basement permeability, test the reliability of conductive‐proxy models used to estimate basement permeability for this setting, and examine the evolution of the hydrothermal circulation system as sediment accumulates. We find hydrothermal basement permeabilities ≥10−10 m2 are required for the top of basement near Sites 1026 and 1027 to be nearly isothermal, consistent with results from the conductive‐proxy models. Modelled fluid circulation in the direction that allows both the observed sign of temperature difference between Sites 1026 and 1027 (warmer in the basement high) and a close approximation of the observed relative basement pressures is only achieved with a heterogeneous permeability distribution, connected high permeability conduits hosted within low permeability rock. This suggests that ridge flank hydrothermal circulation in this setting occurs dominantly within narrow zones of elevated permeability, consistent with observed, scale‐dependent variations in permeability in this region, and conceptual models of heterogeneous hydrogeologic systems in general.
Determining tephra fall deposit thickness in sedimentary record from magnetic susceptibility curve: Example of four Ethiopian tephras
Authors: Touchard Y. , Rochette P.
Published: February 2004

The ejecta volume associated to a volcanic eruption is commonly estimated by extrapolating the exponential thinning relations beyond the tephra fall deposit thickness preserved in the sedimentary record. The thickness of a tephra is usually determined visually, eventually including the counting of the volcanic grains to take into account the vertical dilution of volcanic material within the sedimentary column. An alternative method is presented. Most of tephra fall deposits preserved within marine sedimentary records are marked by magnetic susceptibility peaks, that stand out against the low signal usually observed in marine environment. The peak area is proportional to the thickness of the tephra and to the specific magnetic susceptibility of volcanic material χvol. Therefore integrating the surface below a gaussian fit of dry mass magnetic susceptibility corrected from the sedimentary background magnetic contribution gives the apparent tephra fall deposit thickness, knowing χvol. This method is applied to four Ethiopian traps tephra observed in four sites from Ocean Drilling Program (ODP) Leg 115, drilled in the southern Indian Ocean, 2600 km away from the Ethiopian traps. The characteristics of magnetic susceptibility peaks associated to the tephras vary from one site to one other, with lithology, sedimentation rate and bioturbation. Despite these different conditions, estimations of tephra thicknesses are similar in all sites, as expected for close sites. These tephras are interpreted as markers of four ignimbrite‐forming eruptions as important as the Toba eruption at 75 k.y., during a long‐lived eruptive phase.
Solar EUV irradiance variability derived from terrestrial far ultraviolet dayglow observations
Authors: Strickland D. J. , Lean J. L. , Meier R. R. , Christensen A. B. , Paxton L. J. , Morrison D. , Craven J. D. , Walterscheid R. L. , Judge D. L. , McMullin D. R.
Published: February 2004

Remotely sensed ultraviolet emissions from the Earth's upper atmosphere are shown to mirror fluctuations in solar EUV irradiance during July 2002, including the overall increase and decrease as the Sun rotated, and episodic increases associated with multiple solar flares. The TIMED/GUVI dayglow observations are used to derive a new quantity, QEUVGUVI, which is a measure of integrated solar EUV electromagnetic energy shortward of 45 nm. Both the absolute QEUVGUVI values and their modulation by solar rotation agree well with the corresponding solar EUV energy estimated by the NRLEUV irradiance variability model. The QEUVGUVI values do not support recent suggestions that the solar EUV irradiances estimated by the model of Hinteregger et al. be increased by a factor of four, nor even a factor of two.
First tristatic studies of meso‐scale ion‐neutral dynamics and energetics in the high‐latitude upper atmosphere using collocated FPIs and EISCAT radar
Authors: Aruliah A. L. , Griffin E. M. , McWhirter I. , Aylward A. D. , Ford E. A. K. , Charalambous A. , Kosch M. J. , Davis C. J. , Howells V. S. C.
Published: February 2004

A unique experiment was undertaken during the nights of 27 and 28 February 2003. Tristatic Fabry‐Perot Interferometer (FPI) measurements of the upper thermosphere were co‐located with tristatic EISCAT radar measurements of the ionosphere. Tristatic measurements should remove assumptions of uniform wind fields and ion drifts, and zero vertical winds. The FPIs are located close to the 3 radars of the EISCAT configuration in northern Scandinavia. Initial studies indicate that the thermosphere is more dynamic and responsive to ionospheric forcing than expected. Mesoscale variations are observed on the scales of tens of kilometers and minutes. The magnitude of the upper thermosphere neutral wind dynamo field is on average 50% of the magnetospheric electric field and contributes an average magnitude of 41% of in‐situ Joule heating. The relative orientations of the 2 dynamo field vectors produce a standard deviation of ±65% in the contribution of the neutral wind dynamo.
A high‐resolution simulation of convective roll clouds during a cold‐air outbreak
Authors: Liu A. Q. , Moore G. W. K. , Tsuboki K. , Renfrew I. A.
Published: February 2004

A ubiquitous feature of the high latitude ocean is the occurrence of convective clouds that are organized into two‐dimensional structures known as roll clouds or cloud streets. In this paper, we present a simulation of these structures that was performed in a domain large enough to simulate numerous roll clouds and their downstream evolution at a resolution sufficient to resolve the individual convective clouds. The simulations were initialized and validated using observations of roll clouds over the Labrador Sea. The model results indicate that the secondary flow associated with the roll clouds results in significant differences in the temperature, humidity and momentum fields between the updrafts and downdrafts. The model was also able to reproduce the observed downstream evolution of the clouds as the organization of the convection changed from two‐dimensional rolls to three‐dimensional closed cells.
Wavelet analysis of Amazon hydrological regime variability
Authors: Labat David , Ronchail Josyane , Callede Jacques , Guyot Jean Loup , De Oliveira Eurides , Guimarães Waldemar
Published: February 2004

Wavelet analysis allows for an insightful examination of the temporal variability of Amazon basin hydrology and highlights intermittent interannual and interdecadal fluctuations. Two main conclusions arise. Interannual fluctuations appear as closely related to equatorial Pacific forcings whereas 15‐year and bi‐decadal fluctuations are strongly correlated with Pacific and tropical Atlantic long term forcings. The 1970's climate shift affects the Amazon basin, implying a correlation between both NATL and SOI and hydrological proxies after that decade.
WWLL global lightning detection system: Regional validation study in Brazil
Authors: Lay Erin H. , Holzworth Robert H. , Rodger Craig J. , Thomas Jeremy N. , Pinto Osmar , Dowden Richard L.
Published: February 2004

An experimental lightning detection network, the World Wide Lightning Location network (WWLL), is being developed to provide real time global coverage with 10 km location accuracy and at least 50% detection efficiency. This paper provides a “worst case” analysis of WWLL location accuracy in Brazil where the VLF lightning receivers that make up the network are very distant (>7000 km). Through comparison to a local lightning detection network, we analyze the detection accuracy in Brazil with respect to time, location, and peak current of lightning strokes. In this study, we find that WWLL detection is highly dependent upon the peak return stroke current, resulting in detection of about 0.3% of the total lightning strokes. However, the detected strokes have a location accuracy of 20.25 ± 13.5 km and a temporal accuracy of 0.06 ± 0.2 ms, providing a good overview of regions of overall global lightning activity in real time.
Seismic structure of the crust and uppermost mantle in the incipient stage of back arc rifting — northernmost Okinawa Trough
Authors: Nakahigashi Kazuo , Shinohara Masanao , Suzuki Sadaomi , Hino Ryota , Shiobara Hajime , Takenaka Hiroshi , Nishino Minoru , Sato Takeshi , Yoneshima Shinji , Kanazawa Toshihiko
Published: February 2004

In 1999, a marine seismic structure survey was conducted in the northernmost Okinawa Trough. Outcrops of the acoustic basement through the sedimentary layers are seen in the obtained structures. Velocities of lower layer in upper crust are varying laterally from 5.7 to 6.2 km/s and thickness of 6.0‐km/s layer ranges from 3 to 9 km. The lower crust has uniform thickness of about 15 km. The Pn velocity is 7.7–7.8 km/s and the total crustal thickness is about 25 km including sedimentary layers. The structure is in a first approximation similar to that of island arcs. However, the large heterogeneity of upper crust can be interpreted as a result of crustal thinning. The low Pn velocity and the outcrops of the acoustic basement relate to igneous activity in this area. These results suggest that the northernmost part of the Okinawa Trough is in the incipient stage of a back arc rifting.
Regional variation of spring N‐uptake and new production in the Southern Ocean
Authors: Savoye Nicolas , Dehairs Frank , Elskens Marc , Cardinal Damien , Kopczyńska Elżbieta E. , Trull Thomas W. , Wright Simon , Baeyens Willy , Griffiths F. Brian
Published: February 2004

Nitrate, ammonium and urea uptake were examined in the Southern Ocean (Australian sector) during the 2001 austral spring. On the basis of N‐uptake conditions, three regions were distinguished: (1) the Sub‐Antarctic Zone and the Sub‐Antarctic Front, (2) the Polar and Inter‐Polar Frontal Zones, and (3) the Antarctic Zone‐South and the Seasonal Ice Zone. N‐uptake was highest in region 3 and dominated by new production. Region 1 had the lowest N‐uptake, and switched from regenerated to new production between two visits approximately 1 month apart. Region 2 displayed intermediate N‐uptake and the lowest new production. This contrasts with previous study at 170°W where new production was high around the Polar Front and indicates that this area is not highly productive nor particle‐exporting at all longitudes. Overall, N‐uptake and new production were low all along the latitudinal transect compared to other areas of the Southern Ocean under spring conditions.
Breaking into the plate: A 7.6 Mw fracture‐zone earthquake adjacent to the Central Indian Ridge
Authors: Bohnenstiehl DelWayne R. , Tolstoy Maya , Chapp Emily
Published: February 2004

On 15 July 2003 an extremely large (7.6 Mw) strike‐slip earthquake initiated on or near the end of an active transform along the northern Central Indian Ridge. The event propagated away from the plate boundary along the typically inactive fracture zone, with a sense of slip that opposes the active transform slip direction. Seismically and hydroacoustically determined aftershock locations delineate a 210 ± 25 km long mainshock rupture. The seismic moment and rupture dimensions imply a stress drop of 4.5–6.5 MPa and a mean slip of 3.0 ± 0.5 m. The largest aftershock (5.6 Mw) occurred on the active portion of a neighboring transform at a distance of ∼160 km, where mainshock‐induced static stress changes are predicted to promote failure. Near‐axis fracture‐zone earthquakes may promote and inhibit ridge‐parallel diking along different spreading segments, perhaps contributing to inter‐segment variability in the rate and asymmetry of spreading.
Monsoon low‐frequency intraseasonal oscillation and ocean‐atmosphere coupling over the Indian Ocean
Authors: Rajendran K. , Kitoh A. , Arakawa O.
Published: February 2004

The impact of coupled interaction over Indian Ocean on the monsoon low‐frequency intraseasonal oscillation is investigated by analysing the simulations of MRI coupled general circulation model (CGCM) and its stand alone atmospheric version (AGCM). Composites of northward propagations constructed based on objective criteria show that the characteristics of CGCM simulated low‐frequency intraseasonal oscillation are close to observation. In CGCM, the atmosphere impacts SST through wind, evaporation, and radiation anomalies and the ocean modulates atmospheric convection through intraseasonal SST fluctuations. But, in AGCM, SST acts only as a boundary forcing without any significant contribution from atmosphere in modulating SST. As a result, the simulated low frequency oscillation lacks many of the important features associated with its amplitude, phase and life‐cycle. These results warrant the use of coupled GCMs for simulating and studying monsoon low‐frequency oscillation.
Postseismic relaxation driven by brittle creep: A possible mechanism to reconcile geodetic measurements and the decay rate of aftershocks, application to the Chi‐Chi earthquake, Taiwan
Authors: Perfettini H. , Avouac J.‐P.
Published: February 2004

We evaluate the effect of coseismic stress changes on the fault slip at midcrustal depth, assuming a velocity‐strengthening brittle creep rheology. We show that this model can help reconcile the time evolution of afterslip, as measured from geodesy, with aftershocks decay. We propose an analytical expression for slip of the brittle creeping fault zone (BCFZ) that applies to any dynamic or static stress perturbation, including shear stress and normal stress changes. The model predicts an initial logarithmic increase of slip with time. Postseismic slip rate decays over a characteristic time tr = that does not depend on the amplitude of the stress perturbation, and it asymptotically joins the long‐term creep imposed by interseismic stress buildup . Given that the seismicity rate might be considered proportional to the sliding velocity of the BCFZ, the model predicts a decay rate of aftershocks that follows Omori's law, with a mathematical formalism identical to that of Dieterich [1994] although based on a different mechanical rationale. Our model also differs from Dieterich's model in that it requires that aftershock sequences and deep afterslip, as constrained from geodetic measurements, should follow the same temporal evolution. We test this for the 1999 Chi‐Chi earthquake, Mw = 7.6 and find that both sets of data are consistent with a model of afterslip due to the response of the BCFZ. The inferred relaxation time tr = 8.5 years requires a value for a = ∂μ/∂log(V) (μ being the coefficient of friction) in the range between 1.3 10−3 and 10−2.
Harzburgite melting with and without H2O: Experimental data and predictive modeling
Authors: Parman Stephen W. , Grove Timothy L.
Published: February 2004

The effect of H2O on harzburgite‐saturated melts has been quantified with a series of hydrous and anhydrous melting experiments using a piston‐cylinder device. Experimental conditions were 1.2–2.2 GPa and 1175–1500°C. Melt H2O contents range from 0 to 10 wt %. The effects of temperature, pressure, and bulk composition (including H2O) on the SiO2 content of the experimental melts have been evaluated using SiO2 activity coefficients. The results suggest a two‐lattice‐type model for the melt phase in which H2O mixes nearly ideally with other network modifiers (MgO, FeO, etc.) but does not mix on the network‐forming lattice site and so has little effect on SiO2 activity coefficients. The effect of H2O on SiO2 activity is too small to produce the high SiO2 contents observed in mafic andesite magmas. It is proposed that the SiO2‐rich character of hydrous, subduction‐related magmas is the result of the low temperatures at which hydrous melting occurs relative to anhydrous melting. Partition coefficients for MgO and FeO increase at lower temperatures, while the partition coefficient for SiO2 is nearly constant and is buffered by olivine‐orthopyroxene equilibria. Therefore the SiO2/(MgO + FeO) ratios of harzburgite saturated melts increase as temperature falls in both hydrous and anhydrous systems. The results suggest that H2O contents of andesitic magmas may be far higher (>7 wt %) than is generally accepted. Experimentally measured mineral/melt partition coefficients (this study and literature data) have been parameterized in terms of pressure, temperature, and melt H2O content. These expressions have been used to construct a Gibbs‐Duhem‐based numerical model that predicts the compositions of hydrous and anhydrous olivine‐orthopyroxene‐saturated melts. Comparisons with experimental data not included in the model indicate that it is the most accurate model available for predicting the compositions of high‐degree mantle melts, with or without H2O.
Ridge subduction at an erosive margin: The collision zone of the Nazca Ridge in southern Peru
Authors: Hampel Andrea , Kukowski Nina , Bialas Joerg , Huebscher Christian , Heinbockel Raffaela
Published: February 2004

The 1.5‐km‐high, obliquely subducting Nazca Ridge and its collision zone with the Peruvian margin have been imaged by wide‐angle and reflection seismic profiles, swath bathymetry, and gravity surveying. These data reveal that the crust of the ridge at its northeastern tip is 17 km thick and exhibits seismic velocities and densities similar to layers 2 and 3 of typical oceanic crust. The lowermost layer contributes 10–12 km to the total crustal thickness of the ridge. The sedimentary cover is 300–400 m thick on most parts of the ridge but less than 100 m thick on seamounts and small volcanic ridges. At the collision zone of ridge and margin, the following observations indicate intense tectonic erosion related to the passage of the ridge. The thin sediment layer on the ridge is completely subducted. The lower continental slope is steep, dipping at ∼9°, and the continental wedge has a high taper of 18°. Tentative correlation of model layers with stratigraphy derived from Ocean Drilling Program Leg 112 cores suggests the presence of Eocene shelf deposits near the trench. Continental basement is located <15 km landward of the trench. Normal faults on the upper slope and shelf indicate extension. A comparison with the Peruvian and northern Chilean forearc systems, currently not affected by ridge subduction, suggests that the passage of the Nazca Ridge along the continental margin induces a temporarily limited phase of enhanced tectonic erosion superposed on a long‐term erosive regime.