bluuebunny/crossref_metadata_2025 huggingface dataset:
Zonal approach to centrifugal, elliptic and hyperbolic instabilities in Stuart vortices with external rotation
Authors: GODEFERD FABIEN S. , CAMBON CLAUDE , LEBLANC S.
Published: November 2006

The stability analysis of a street of Stuart vortices in a rotating frame is performed
by integrating the Kelvin–Townsend equations along the mean flow trajectories,
using the geometrical optics technique (Lifschitz & Hameiri 1991) for short-wave
perturbations. A parallel is drawn between the formulations of this zonal approach
and that of rapid distortion theory, better known to the turbulence community. The
results presented confirm those obtained by the standard stability analysis based on
normal-mode decomposition: depending on the rotation parameter and the oblique
mode considered, three unstable zones are identified, related to the centrifugal, elliptic
and hyperbolic instabilities, as observed for Taylor–Green cells (Sipp et al. 1999).
Anticyclonic rotation is shown to destabilize Stuart vortices through a combination
of the elliptical and centrifugal instability mechanisms, depending on the ratio of
its rate to the structure core vorticity. Available stability criteria are discussed in the
general case of two-dimensional rotating flows, in relation to their streamline topology
and the values of the local Rossby number or vorticity.
Investigating the abstractness of children's early knowledge of argument structure
Authors: MCCLURE KATHLEEN , PINE JULIAN M. , LIEVEN ELENA V. M.
Published: November 2006

In the current debate about the abstractness of children's early grammatical knowledge, Tomasello & Abbott-Smith (2002) have suggested that children might first develop ‘weak’ or ‘partial’ representations of abstract syntactic structures. This paper attempts to characterize these structures by comparing the development of constructions around verbs in Tomasello's (1992) case study of Travis, with those of 10 children (Stage I–II) in a year-length, longitudinal study. The results show some evidence that children's early knowledge of argument structure is verb-specific, but also some evidence that children can generalize knowledge about argument structure across verbs. One way to explain these findings is to argue that children are learning limited scope formulae around high frequency subjects and objects, which serve as building blocks for more abstract structures such as S+V and V+O. The implication is that children may have some verb-general knowledge of the transitive construction as early as Stage I, but that this knowledge is still far from being fully abstract knowledge.
Testing the Agreement/Tense Omission Model using an elicited imitation paradigm
Authors: AMBRIDGE BEN , PINE JULIAN M.
Published: November 2006

The present study used an elicited imitation paradigm to test the prediction of Schutze & Wexler's (1996) AGREEMENT/TENSE OMISSION MODEL (ATOM) that the rate of non-nominative subjects with agreement-marked verb forms will be sufficiently low that such errors can reasonably be disregarded as noise in the data. A screening procedure identified five children who produced non-nominative subject errors (all her for she) who were then asked to repeat 24 sentences with 3sg feminine pronoun subjects (she) and agreeing main verbs or auxiliaries. All five children produced at least one non-nominative subject (her) with an agreement-marked verb form, and for none of these five children was the non-NOM+AGR rate significantly different to the rate that would be expected by chance, given the independent frequencies of non-nominative subjects and agreement-marked verb forms in their data. The three children for whom this expected (by chance) error rate was significantly greater than 10% (representing an acceptable level of noise in the data) produced non-NOM+AGR errors at a rate significantly greater than 10%, counter to the prediction of the ATOM. These results replicate and extend the naturalistic-data findings of Pine et al. using a different method. They also provide support for the use of elicited imitation as a methodology for assessing children's early grammatical knowledge.
The development of referential choice in English and Japanese: a discourse-pragmatic perspective
Authors: GUERRIERO A. M. SONIA , OSHIMA-TAKANE YURIKO , KURIYAMA YOKO
Published: November 2006

The present research investigated whether children's referential choices for verb arguments are motivated by pragmatic features of discourse referents across different developmental stages, not only for children learning null argument languages but also for those learning overt argument languages. In Study 1, the form (null, pronominal, or lexical) and referential status (given or new) of verb arguments were systematically analysed in six English-speaking and six Japanese-speaking children and their mothers when the children were at 1;9 and 3;0. In Study 2, non-linguistic pragmatic correlates (pointing, reaching, moving, making a head motion, or purposeful gaze direction toward a referent) were analysed in addition to the form and referential status of arguments at each of four linguistic periods between MLU 1·00 and 4·00 in two English-speaking and two Japanese-speaking children and their mothers. The results revealed that, when both linguistic and non-linguistic referential behaviours were considered, the English-speaking children showed patterns consistent with language-universal as well as language-specific discourse-pragmatic principles by 2;0 (between MLU 2·00 and 2·99), whereas the Japanese-speaking children did not show these patterns even as late as 3;0 (MLU 4·00 and above). Results also indicated that the children who were exposed to more consistent discourse-pragmatic referential patterns from their input tended to show these patterns earlier than those exposed to inconsistent patterns. Together these findings suggest that both the referential status of discourse referents as well as parental input predict children's referential choices across typologically different languages.
Editorial
Authors: THOMPSON JUNE
Published: November 2006

This issue of ReCALL represents something of a watershed in the journalÕs history, for a number of reasons. First of all I have to report that Professor Graham Chesters has decided that he wishes to step down as co-editor, and I would like to thank him here for all his work for the journal over the years. Back in 1990 when Graham and I were involved with the Computers in Teaching Initiative Centre for Modern Languages (CTICML) at the University of Hull, funded by the UK Higher Education Funding Council, one of the required ‘deliverables’ was a regular Newsletter, designed to inform university language lecturers about developments in the use of new technologies in language learning. It soon became apparent that some of the material that was being submitted for publication was far too substantial for a Newsletter, yet merited dissemination among our readers. It was Graham who saw the potential need for a new academic journal in this field, and thus ReCALL was born. I still blush to see my attempts at desk-top publishing in those early issues!
Exploring German preservice teachers’ electronic and professional literacy skills
Authors: FUCHS CAROLIN
Published: November 2006

This article presents findings from an exploratory pilot project which aimed at fostering electronic and professional literacy skills of preservice language teachers through computer-mediated peer collaboration. The research context is a qualitative case study involving cooperation via the email and chat functions of FirstClass among preservice teachers at the Justus-Liebig Universität in Giessen and the Pädagogische Hochschule Heidelberg in Germany. The author investigates participants’ prior experiences with regard to computer skills, Internet proficiency, and technology-based language learning and teaching. Next, she discusses benefits and challenges for preservice teachers with respect to collaborating via computers (computer-mediated communication or CMC) with their transatlantic partners. In collecting and analyzing preservice teachers’ reflections, a Grounded Theory approach (Strauss & Corbin, 1998) was used. Instances of electronic and professional literacies were identified and triangulated with data from pre-course questionnaires, post-course self-assessments, logs, email and chat transcripts, and field notes. The author discusses benefits and challenges which preservice teachers encountered through the collaboration. Findings include preservice teachers’ differing levels of electronic literacy skills, tolerance for ambiguity, institutional constraints, peer feedback, and perception of the final product. Based on her findings, the author stresses the need to encourage preservice teachers’ meta-level reflections on the challenges of the collaboration and suggests conducting longitudinal follow-up studies in order to investigate if and how in-service teachers apply the knowledge they gained from their teacher education program to their own teaching.
Evaluating computer-based and paper-based versions of an English-language listening test
Authors: CONIAM DAVID
Published: November 2006

This paper describes an English language listening test intended as computer-based testing material for secondary school students in Hong Kong, where considerable attention is being invested in online and computer-based testing. As well as providing a school-based testing facility, the study aims to contribute to the knowledge base regarding the efficacy and reliability of computer-based testing. The paper describes the construction of an item bank of over 400 short listening items calibrated on item response theory principles. Items from this bank were used to form a traditional paper-based listening test, and an adaptive computer-based test. Both forms of the test were administered to two Hong Kong Grade 11 and Grade 12 classes. Descriptive test statistics indicated that both test types discriminated effectively between school grades. In terms of comparability between test types, there was significant difference between the Grade 11 classes’ performance although not with that of Grade 12. Test takers generally performed better on the computer-based test than on the paper-based test, confirming earlier research. Interviews with test takers after taking both tests indicated an even split in terms of preference, with boys opting for the computer-based test and girls the paper-based test. Correlations between test takers’ performance on the two test types were high enough to indicate the computer-based test’s potential as a low-stakes test (its intended purpose as a school-based testing facility), although not as a high-stakes test (for example, as a territory-wide test replacing a traditional paper-based test).
Sociocultural theory and its application to CALL: A study of the computer and its relevance as a mediational tool in the process of collaborative activity
Authors: GÁNEM GUTIÉRREZ GABRIELA ADELA
Published: November 2006

This study in the field of Second Language Acquisition (SLA) was conducted in a Spanish as a foreign language classroom. The study investigates dyadic face-to-face collaborative dialogue at the computer from a sociocultural perspective. Protocols for analysis were obtained by the transcription of audio recordings of twelve dyads/triads completing three tasks in two mediums of implementation, computer and non-computer-based. By comparing learners’ activity in the two mediums through microgenetic analysis (i.e., developmental analysis), we were able to study some specific ways in which the computer influenced the course of interaction. Specifically, the aim of the study was to investigate the value of the tasks as pedagogical instruments to support collaborative activity in the foreign language classroom; the value of collaborative activity as a source for possible restructuring of interlanguage (i.e., microgenesis); and the impact of the computer as a mediational tool in the processes of collaborative activity. Results confirm: (1) the three tasks support high degrees of collaborative activity – albeit qualitatively different; (2) language can – sometimes simultaneously – be deployed by learners both as a means of communication and as a cognitive tool to achieve linguistic development; (3) the presence of the computer seems to change the nature of collaborative activity.
Agranulozytose bei einem mit Metamizol und Clopidogrel behandelten Patienten
Authors: Kummer  , Haschke  , Tuchscherer  , Lampert  , Martius  , Krähenbühl
Published: November 2006

Wir berichten über einen 75-jährigen Patienten, der drei Wochen nach einem ischämischen zerebrovaskulären Insult eine Agranulozytose entwickelte und anschliessend an einer Pneumonie erkrankte. Als mögliche Ursachen für die Agranulozytose konnten am ehesten Metamizol oder Clopidogrel identifiziert werden. Die Agranulozytose ist eine seltene, aber ernst zu nehmende unerwünschte Arzneimittelwirkung. Seit 1997 wurden den Schweizer Arzneimittelbehörden sechs Fälle von Agranulozytose unter Metamizol und zwei unter Clopidogrel gemeldet. Die Therapie besteht in der Injektion von hämatopoietischem Wachstumsfaktor (G-CSF, granulocyte colony stimulating factor) sowie der Gabe von breit wirksamen Antibiotika im Falle einer bakteriellen Infektion. Bei adäquater Therapie ist die Prognose gut. Wir diskutieren den Einsatz des Analgetikums und Antipyretikums Metamizol in der Akut- und Langzeittherapie.
Die Behandlung des akuten Myokardinfarkts: eine Zeit-Angelegenheit
Authors: Kaiser
Published: November 2006

Der akute Myokardinfarkt ist in der Schweiz mit über 12000 Fällen pro Jahr ein häufiges Krankheitsbild mit einer weiterhin hohen Gesamtmortalität von über 40%. Pathophysiologisch entsteht ein Infarkt durch eine Ruptur einer koronaren Plaque mit in der Folge thrombotischem Verschluss des Herzkranzgefässes. Die einzig wirksame und mögliche Therapie ist die Reperfusion des verschlossenen Gefässes, wobei diese möglich rasch erfolgen sollte. Je schneller das Gefäss wiedereröffnet wird, desto besser ist die Prognose: Zeitersparnis rettet Myokard und reduziert Mortalität und Morbidität! Im Rahmen einer Metaanalyse konnte gezeigt werden, dass die mechanische Wiedereröffnung des Herzkranzgefässes mittels Ballondilatation und Stentversorgung der medikamentösen Thrombolyse überlegen ist. Sie gilt heutzutage als Reperfusionsstrategie der ersten Wahl. Patienten mit akutem ST-Streckenhebungsinfarkt sollten deshalb ohne Verzögerung einem Spital mit der Möglichkeit einer interventionellen Reperfusion zugeführt werden.
Adjektivliste zur Erfassung der Wahrgenommenen Körperlichen Verfassung (WKV)
Authors: Kleinert Jens
Published: November 2006

Zusammenfassung. Zielsetzung der vorliegenden Arbeit ist die Konstruktion und Validierung einer Skala zur Erfassung der aktuell wahrgenommenen körperlichen Verfassung. Auf der Basis eines durch Experten bewerteten Adjektivpools wurde eine 48 Items umfassende Vorversion konstruiert (WKV-48) und an einer Gruppe von 119 Sportstudierenden erprobt. Eine exploratorische Faktorenanalyse führte zu einer 4-Faktoren-Struktur der Daten, auf deren Basis eine 20-Item-Endversion (WKV) erstellt wurde, die an 645 gesunden und kranken Menschen unterschiedlichen Alters und unterschiedlicher sportlicher Erfahrung validiert wurde. Während sich in konfirmatorischen Faktorenanalysen keine zufrieden stellende Anpassungsgüte zum 4-Faktoren-Modell ergab, fielen die Reliabilität der Subskalen und insbesondere die Sensibilität der Skala für Veränderungen der körperlichen Zustandslage zufrieden stellend bis sehr gut aus. Korrelationen zur psychischen Befindlichkeit waren zumeist signifikant, aber gering ausgeprägt. Insgesamt empfiehlt sich die Skala insbesondere für die Verlaufskontrolle der aktuellen körperlichen Befindlichkeit im Bereich der Prävention und Rehabilitation.
Translating Tests
Authors: Van de Vijver Fons , Hambleton Ronald K.
Published: November 2006

With the increasing interest in cross-cultural research, there is a growing need for standard and validated practices for translating psychological instruments. Developing a psychologically acceptable instrument for another cultural group almost always requires more effort than a literal translation, which all too often is the common practice. The adequacy of translations can be threatened by various sources of bias. Three types of bias are distinguished in this paper: (1) construct bias (related to nonequivalence of constructs across cultural groups), (2) method bias (resulting from instrument administration problems), and (3) item bias (often a result of inadequate translations such as incorrect word choice). Ways in which bias can affect the adequacy of instruments are illustrated and possible remedies are discussed.
Continuing Professional Development in the British Psychological Society
Authors: Lindley Patricia A.
Published: November 2006

The paper examines various interpretations of continuing professional development (CPD). The differing perspectives on CPD of the individual practitioner, their employing organization, and their professional body are discussed. In addition, three distinct uses of CPD are outlined. These are characterized by differential emphasis on the continuing,.professional, and developmental aspects of CPD. Professional bodies, because of their need to protect the standards of the profession, tend to focus their attention on the second of these three meanings. Professional bodies also differ in the ways they can address CPD. They can employ either voluntary, obligatory, or mandatory approaches. The implications of each of these for the profession and the professional body are discussed. Finally, the current status of CPD within the British Psychological Society (BPS) is outlined and implications for the future are highlighted.
Temperament and the Discounting of Delayed and Probabilistic Rewards
Authors: Ostaszewski Pawel
Published: November 2006

The present study attempts to combine the more European tradition of studying temperament and individual differences with the more North American tradition of functionalism and behavior analysis by examining the relationship between several temperamental traits (sensation seeking, extraversion, and impulsivity) and discounting of delayed and probabilistic rewards. To evaluate discounting of delayed rewards, participants chose between hypothetical immediate monetary rewards and larger amounts that could be obtained after a specified delay. To evaluate discounting of probabilistic rewards, participants chose between monetary rewards that were certain and larger amounts that could be obtained with a specified probability.

Hyperbolic functions described well the discounting of both delayed and probabilistic rewards for all groups of participants. The rate at which delayed rewards were discounted was related to extraversion and impulsivity, but not to the sensation-seeking dimension. Both extraverts and high impulsive individuals showed higher temporal discounting rates than introverts and low impulsive individuals.

Differences in their subjective perception of time might account for the different rates of discounting between these groups. On the other hand, the rate at which probabilistic rewards were discounted did not differ between high and law impulsive participants, nor between introverts and extraverts. That temperament was related to differences in discounting of delayed but not probabilistic rewards in extraverts versus introverts and high versus low impulsive participants suggests that, although the same mathematical function describes both forms of discounting in all groups, delay and probability might not be functionally equivalent.
Changes in the Stereotypical Portrayal of Men and Women in British Television Advertisements
Authors: Furnham Adrian , Skae Emma
Published: November 2006

This study examines the way in which men and women are portrayed in British television advertisements, and these findings are compared with those of studies carried out in Britain over the past 25 years. A total of 162 television advertisements were analyzed by two white adults, one female, one male, in order to obtain reliable results. The attributes of the central figures in each of the advertisements were classified into 11 categories: gender, mode of presentation, credibility basis, role, location, age, argument, reward type, product type, background, and end comment. Advertisements aimed directly at men or women were then analyzed, according to the sex of the central figure and the sex of the consumer the advertisement is aimed at. Thereafter, advertisements that did not follow the sex-role stereotype were also analyzed. The study found that while differences between the portrayal of men and women have been reduced in some categories, in others the stereotypical portrayal has changed in both sexes. The findings are related to data from another cross-cultural European study using identical methodology.
Mineralogical characterization of protolith and fault rocks from the SAFOD Main Hole
Authors: Solum John G. , Hickman Stephen H. , Lockner David A. , Moore Diane E. , van der Pluijm Ben A. , Schleicher Anja M. , Evans James P.
Published: November 2006

Washed cuttings provide a continuous record of the rocks encountered during drilling of the main hole of the San Andreas Fault Observatory at Depth (SAFOD). Both protolith and fault rocks exhibit a wide variety of mineral assemblages that reflect variations in some combination of lithology, P‐T conditions, deformation mechanisms, and fluid composition and abundance. Regions of distinct neomineralization bounded by faults may record alteration associated with fluid reservoirs confined by faults. In addition, both smectites occurring as mixed‐layer phases and serpentine minerals are found in association with active strands of the San Andreas Fault that were intersected during drilling, although their rheological influence is not yet fully known. Faults containing these mineralogical phases are prime candidates for continuous coring during Phase 3 of SAFOD drilling in the summer of 2007.
Adjoint‐based forecast sensitivities of Typhoon Rusa
Authors: Kim Hyun Mee , Jung Byoung‐Joo
Published: November 2006

Sensitivities of the forecast to changes in the initial state are evaluated for Typhoon Rusa, which passed through the Korean Peninsula in 2002, to understand the impact of initial condition uncertainties on the forecast and thence to diagnose the sensitive regions for adaptive observations. To assess the forecast sensitivities, adjoint‐based sensitivities were used. Sensitive regions are located horizontally in the right half circle of the typhoon, and vertically in the lower and upper troposphere which coincide with the inflow and outflow regions near the typhoon. Forecast error is reduced around 18% by extracting properly weighted adjoint‐based forecast sensitivity perturbations from the initial state, and the correction occurs primarily in the lower to mid‐troposphere where the forecast error is the largest. In contrast to the improvement in the overall forecast, the track and intensity forecast are not improved much through the modification of the initial condition by adjoint‐based forecast sensitivities.
Hydrothermal buffering of the SO2/H2S ratio in volcanic gases: Evidence from La Fossa Crater fumarolic field, Vulcano Island
Authors: Aiuppa A. , Federico C. , Giudice G. , Gurrieri S. , Valenza M.
Published: November 2006

Sulfur speciation in volcanic gases is a potentially valuable tracer of degassing processes at volcanoes. Hitherto, observations of sulfur speciation in volcanic gas plumes have however been limited both in number and quality. Here, we report on periodic measurements of SO2 to H2S proportions in the volcanic gases from La Fossa volcano (Vulcano Island) performed during 2004–2006, a period which encompasses two heating events of the fumarolic field in January–April 2005 and December 2005. Results indicate a systematic relative increase (by a factor of 2–6) of SO2 to H2S proportions in the fumaroles during the heating events, which we ascribe to a temperature increase in the mixing zone between magmatic and hydrothermal fluids. We also demonstrate that sulphur speciation in La Fossa fumaroles reflects re‐equilibration within a poly‐baric hydrothermal system, and that this hydrothermal re‐equilibration erases the pristine SO2/H2S ratios of any magma‐derived sulphur present.
Fault slip rates from three‐dimensional models of the Los Angeles metropolitan area, California
Authors: Cooke Michele L. , Marshall Scott T.
Published: November 2006

We present results from the first mechanical model of active tectonics in the Los Angeles region to use non‐planar, geologically representative fault surfaces compiled by the Southern California Earthquake Center Community Fault Model. The fault slip rates from our three‐dimensional model match well the available geologic slip rates. Discrepancies in reverse slip along the Upper Elysian Park fault and strike‐slip along the Raymond fault may reflect imprecise knowledge of local fault geometry. Discrepancy in the average dip slip rate along the Palos Verdes fault reveals variations in dip slip along that surface; model predictions at the location of the geological investigation have good match to geologic data. The validated model is used to estimate dip and strike slip rates for 26 active faults in the Los Angeles metropolitan region, many of which are otherwise unconstrained by geologic evidence.
Formation of Saturn's ring spokes by lightning‐induced electron beams
Authors: Jones G. H. , Krupp N. , Krüger H. , Roussos E. , Ip W.‐H. , Mitchell D. G. , Krimigis S. M. , Woch J. , Lagg A. , Fränz M. , Dougherty M. K. , Arridge C. S. , McAndrews H. J.
Published: November 2006

Spokes are near‐linear markings sometimes visible on Saturn's rings. They are widely accepted as being electrostatically‐levitated sheets of ∼0.6 micron‐radius charged grains. Previously‐suggested causes of the grains' charging do not agree with all spoke characteristics, which include their rapid generation, localized formation primarily in Saturn's midnight‐dawn sector, the seasonality of their apparitions, and, crucially, their morphologies. We contend that spokes are caused by lightning‐induced electron beams striking the rings, at locations magnetically‐connected to thunderstorms. This view is supported by a semi‐quantitative spoke morphology simulation. Spokes' formation locations are further controlled by Saturn's ionospheric density, which reaches a near‐dawn minimum where electron beams can most easily propagate to the rings. The beams may generate observed X‐ray emission, supply particles to Saturn's radiation belts, and over time will modify the rings' constituents. Finally, we report Cassini MIMI instrument observations of an electron burst which displays some characteristics expected of a lightning‐induced event.
Analyzing electric field morphology through data‐model comparisons of the Geospace Environment Modeling Inner Magnetosphere/Storm Assessment Challenge events
Authors: Liemohn Michael W. , Ridley Aaron J. , Kozyra Janet U. , Gallagher Dennis L. , Thomsen Michelle F. , Henderson Michael G. , Denton Michael H. , Brandt Pontus C. , Goldstein Jerry
Published: November 2006

The storm time inner magnetospheric electric field morphology and dynamics are assessed by comparing numerical modeling results of the plasmasphere and ring current with many in situ and remote sensing data sets. Two magnetic storms are analyzed, 22 April 2001 and 21–23 October 2001, which are the events selected for the Geospace Environment Modeling (GEM) Inner Magnetosphere/Storms (IM/S) Assessment Challenge (IMSAC). The IMSAC seeks to quantify the accuracy of inner magnetospheric models as well as synthesize our understanding of this region. For each storm, the ring current‐atmosphere interaction model (RAM) and the dynamic global core plasma model (DGCPM) were run together with various settings for the large‐scale convection electric field and the nightside ionospheric conductance, while keeping all other simulation settings the same. DGCPM plasmaspheric parameters were compared with IMAGE‐EUV plasmapause extractions and LANL‐MPA plume locations and velocities. RAM parameters were compared with Dst*, LANL‐MPA fluxes and moments, IMAGE‐MENA images, and IMAGE‐HENA images. Both qualitative and quantitative comparisons were made to determine the electric field morphology that allows the model results to best fit the plasma data at various times during these events. The simulations with self‐consistent electric fields were, in general, better than those with prescribed field choices. This indicates that the time‐dependent modulation of the inner magnetospheric electric fields by the nightside ionosphere is quite significant for accurate determination of these fields (and their effects). It was determined that a shielded Volland‐Stern field description driven by the 3‐hour Kp index yields accurate results much of the time but can be quite inconsistent. The modified McIlwain field description clearly lagged in overall accuracy compared to the other fields, but matched some data sets (like Dst*) quite well. The rankings between the simulations varied depending on the storm and the individual data sets, indicating that each field description did well for some place, time, and energy range during the events, as well as doing less well in other places, times, and energies. Several unresolved issues regarding the storm time inner magnetospheric electric field are discussed.
Ion‐acoustic waves triggered by left‐hand polarized finite‐amplitude waves propagating in the beam direction
Authors: Gomberoff L.
Published: November 2006

Nonlinear ion‐acoustic like waves triggered by large‐amplitude circularly polarized waves propagating in the direction of a proton beam are studied. The properties are strongly dependent on the nature of the large‐amplitude wave. Waves belonging to the Alfvén branch of the dispersion relation require much larger amplitude values to excite the ion‐acoustic waves than those belonging to the beam branch of the dispersion relation. The former can trigger only forward propagating waves and always above a wave number threshold, while the latter can destabilize forward as well as backward propagating waves with a zero wave number threshold. It is shown that in some cases the unstable frequency spectrum is very narrow, and damping rates are very small even under conditions where the linear theory predicts strong Landau damping. It is conjectured that these type of waves might be of common occurrence in the fast solar wind, preferably closer to the Sun. These results are consistent with observation of electrostatic ion‐acoustic like emissions in the solar wind.
Local time distribution of reconnected field lines under northward interplanetary magnetic field conditions
Authors: Petrinec S. M. , Fuselier S. A. , Claflin E. S. , Trattner K. J.
Published: November 2006

Plasma observations in the northern cusp region are used to study the reconnection process and the inflow of plasma into the magnetosphere during intervals of northward interplanetary magnetic field. Several intervals are examined for which He++ of solar wind origin appears simultaneously with downgoing or counterstreaming O+ ions of ionospheric origin. The presence of both He++ and O+ suggests that magnetic reconnection on the magnetopause has occurred. The cases of downgoing or counterstreaming O+ observed in conjunction with He++ suggests that reconnection has occurred tailward of both cusps. The local time distribution of the occurrence of these events is investigated as a function of the state of the solar wind.
Evidence for short spatial correlation lengths of the noontime equatorial electrojet inferred from a comparison of satellite and ground magnetic data
Authors: Manoj C. , Lühr H. , Maus S. , Nagarajan N.
Published: November 2006

The current density of the noontime equatorial electrojet (EEJ) as determined from CHAMP data is highly variable between successive passes of the satellite, which are separated by 23° in distance and 93 min in time. An open question is to which extent this variability is caused by temporal or spatial variations in the ionosphere. Another important question is the connection between EEJ and global solar‐quiet (Sq) current systems. We try to answer these questions by comparing the EEJ current density estimated from high‐quality scalar magnetic field measurements of the CHAMP satellite with the magnetic horizontal intensity variations at six equatorial observatory pairs distributed across the globe. Data taken during the period 2000–2002 were used for the present study. We apply corrections for the effect of local time (LT) and Sq fields. By estimating the correlation coefficients between the ground and satellite data as a function of distances between measurements, new insights into the spatial structure of the EEJ have been obtained. The high correlation, when CHAMP passes directly over an observatory, decays quickly in eastern and western directions. Typically, within ±15° of longitudinal separation between satellite and observatory, the correlation falls well below the statistical significance level. This observation holds for all longitude sectors. Interestingly, the correlation between CHAMP‐inferred EEJ strength and observatory differences breaks down for the observatory pairs, outside of a ±4° latitudinal band. This implies that the EEJ and Sq variations are uncorrelated for periods up to 1 hour. Additionally, it was found that monitoring of the EEJ can be performed best if the reference observatory is 4° to 5° apart from the dip equator.
Recent improvements of the broadband FMCW reflectometry system for density profile measurements on ASDEX Upgrade
Authors: Silva A. , Manso M. , Varela P. , Cupido L. , Meneses L. ,   ASDEX Upgrade Team
Published: November 2006

The broadband FMCW reflectometry system on ASDEX Upgrade has had significant improvements extending its measuring capabilities both on high and low density plasmas: (i) the upgrade of the W band to probe electron densities up to 12.4×1019 m−3 with O mode, (ii) Q and V frequency bands operating in X mode to probe the edge plasma and to provide information for O-mode profile initialization, and (iii) a new dynamic frequency calibration method to take into account all existing delays in the hyperabrupt varactor-tuned oscillator (HTO) tuning port and driver electronics. These improvements are particularly important to measure accurately the edge pedestal region of high density ITER relevant discharges. Density profiles obtained in high density discharges are presented and compared with results from both Li-beam and Thomson scattering diagnostics.
Response model for Kodak Biomax-MS film to x rays
Authors: Knauer J. P. , Marshall F. J. , Yaakobi B. , Anderson D. , Schmitt B. A. , Chandler K. M. , Pikuz S. A. , Shelkovenko T. A. , Mitchell M. D. , Hammer D. A.
Published: November 2006

X-ray-sensitive film is used for a variety of imaging and spectroscopic diagnostics for high-temperature plasmas. Replacement film must be found as older films are phased out of production. Biomax-MS is a “T-grain” class of film that is proposed as a replacement for Kodak DEF and a model of its response to x rays is presented. Data from dimensional measurements of the film, x-ray transmission measurements, scanning electron microscopy micrograph images, and x-ray calibration are used to develop this sensitivity model of Biomax-MS film as a function of x-ray energy and angle of incidence. Relative response data provide a check of the applicability of this model to determine the x-ray flux from spectrum data. This detailed film characterization starts with simple mathematical models and extends them to T-grain–type film.
Millimeter-wave backscatter diagnostic for the study of short scale length plasma fluctuations (invited)
Authors: Rhodes T. L. , Peebles W. A. , Nguyen X. , VanZeeland M. A. , deGrassie J. S. , Doyle E. J. , Wang G. , Zeng L.
Published: November 2006

The development, laboratory tests, and experimental results relating to a new high-k diagnostic technique for the study of short scale length turbulence are reported. The system is based on backscattering of a millimeter-wave (94GHz) probe beam by density fluctuations within the plasma. This diagnostic has been fully integrated with an upgraded far-infrared forward scattering system on the DIII-D tokamak. The combined system monitors a broad turbulent spectral range from 0to40cm−1. Short-scale (e.g., electron temperature gradient scale) modes as well as longer wavelength (e.g., ion temperature gradient and trapped electron mode scale) instabilities are simultaneously monitored to accurately characterize plasma turbulence. The backscattering geometry and innovative use of the second harmonic electron cyclotron resonance as an internal “beam dump” allow detection of small level fluctuations at high k, while maximizing discrimination against the ubiquitous, larger level, low-k fluctuations.
Electron density measurements in the National Spherical Torus Experiment detached divertor region using Stark broadening of deuterium infrared Paschen emission lines
Authors: Soukhanovskii V. A. , Johnson D. W. , Kaita R. , Roquemore A. L.
Published: November 2006

Spatially resolved measurements of deuterium Balmer and Paschen line emission have been performed in the divertor region of the National Spherical Torus Experiment using a commercial 0.5m Czerny-Turner spectrometer. While the Balmer emission lines, as well as the Balmer and Paschen continua in the ultraviolet and visible regions have been extensively used for tokamak divertor plasma temperature and density measurements, the diagnostic potential of infrared Paschen lines has been largely overlooked. We analyze Stark broadening of the lines corresponding to 2−n and 3−m transitions with principal quantum numbers n=7–12 and m=10–12 using recent model microfield method calculations [C. Stehle and R. Hutcheon, Astron. Astrophys., Suppl. Ser. 140, 93 (1999)]. Densities in the range (5–50)×1019m−3 are obtained in the recombining inner divertor plasma in 2–6MW neutral beam heated H-mode discharges. The measured Paschen line profiles show good sensitivity to Stark effects and low sensitivity to instrumental and Doppler broadenings. The lines are situated in the near-infrared wavelength domain, where optical signal extraction schemes for harsh nuclear environments are practically realizable and where a recombining divertor plasma is optically thin. These properties make them an attractive recombining divertor density diagnostic for a burning plasma experiment.
Searching for O-X-B mode-conversion window with monitoring of stray microwave radiation in LHD
Authors: Igami H. , Kubo S. , Laqua H. P. , Nagasaki K. , Inagaki S. , Notake T. , Shimozuma T. , Yoshimura Y. , Mutoh T. , Group LHD Experimental
Published: November 2006

In the Large Helical Device, the stray microwave radiation is monitored by using so-called sniffer probes during electron cyclotron heating. In monitoring the stray radiation, we changed the microwave beam injection angle and search the O-X-B mode-conversion window to excite electron Bernstein waves (EBWs). When the microwave beam is injected toward the vicinity of the predicted O-X-B mode-conversion window, the electron temperature rises in the central part of overdense plasmas. In that case, the stray radiation level near the injection antenna becomes low. These results indicate that monitoring the stray radiation near the injection antenna is helpful in confirming the effectiveness of excitation of EBWs simply without precise analysis.
First tests of molybdenum mirrors for ITER diagnostics in DIII-D divertor
Authors: Rudakov D. L. , Boedo J. A. , Moyer R. A. , Litnovsky A. , Philipps V. , Wienhold P. , Allen S. L. , Fenstermacher M. E. , Groth M. , Lasnier C. J. , Boivin R. L. , Brooks N. H. , Leonard A. W. , West W. P. , Wong C. P. C. , McLean A. G. , Stangeby P. C. , De Temmerman G. , Wampler W. R. , Watkins J. G.
Published: November 2006

Metallic mirrors will be used in ITER for optical diagnostics working in different spectral ranges. Their optical properties will change with time due to erosion, deposition, and particle implantation. First tests of molybdenum mirrors were performed in the DIII-D divertor under deposition-dominated conditions. Two sets of mirrors recessed 2cm below the divertor floor in the private flux region were exposed to a series of identical, lower-single-null, ELMing (featuring edge localized modes) H-mode discharges with detached plasma conditions in both divertor legs. The first set of mirrors was exposed at ambient temperature, while the second set was preheated to temperatures between 140 and 80°C. During the exposures mirrors in both sets were additionally heated by radiation from the plasma. The nonheated mirrors exhibited net carbon deposition at a rate of up to 3.7nm∕s and suffered a significant drop in reflectivity. Net carbon deposition rate on the preheated mirrors was a factor of 30–100 lower and their optical reflectivity in the wave range above 500nm was essentially preserved.
Development of multichannel wave-coincidence neutron spectrometer for fast ignition experiments
Authors: Nakamura H. , Kodama R. , Nakatsutsumi M. , Tampo M. , Toyama Y.
Published: November 2006

We have developed an advanced design for a time-of-flight (TOF) neutron spectrometer applied to the study of ultraintense laser-plasma interactions in the area of fast ignition research. The interaction of an ultraintense laser pulse with plasma creates intense gamma rays, which generate a high level of background noise in the thermal neutron detection process. High energy-density ions, which are generated by strong electric fields associated with the laser interactions, produce beamlike fusion neutrons with an angular distribution that is dependent on the momentum distribution of the ions. These beamlike fusion neutrons also act as a source of significant background noise in the thermal neutron detection process. In order to improve the signal-to-noise ratio (S/N), we have proposed and applied a wave-coincidence method to the neutron detection process. We have demonstrated the advantages of this advanced method in ultraintense laser-plasma interaction experiments, where an improvement in S/N by a factor of 7–8 compared to the conventional TOF method was achieved. We have calculated that the value of S/N increases with the number of detectors used as well as with the initial value of S/N for a single detector.
Nonlinear effects in new magnetic pickup coils for JET
Authors: Quercia A. , Pomaro N. , Visone C. ,   JET-EFDA Contributors
Published: November 2006

In the framework of the JET magnetic diagnostic enhancement, a set of pickup coils (UC subsystem) wound on metallic Inconel® 600 former was manufactured. For cross-validation purposes, two different calibration methods were used. A discrepancy in the range of 3% was observed, which can be explained when considering the dependence of the calibration coefficients on the field strength, which in turn is mostly due to the nonlinear behavior of the Inconel former. For this reason a specimen of Inconel was analyzed by means of a magnetometer, which showed a nonlinear and hysteretic behavior occurring at low field level (below 5 mT). The calibration coefficients are also measured at low field (0.1–2 mT) and so are affected by such peculiar ferromagnetic behavior. Moreover, the ferromagnetic behavior might be sensitive to mechanical and thermal treatments performed during probe manufacturing and testing. Therefore the achievable accuracy for the calibration of coils wound on Inconel formers is limited by the following effects: (i) the field level in operation can be completely different from the field used in the calibration procedure; (ii) measurements of the magnetic properties on Inconel specimens cannot be extrapolated to the former, because of unpredictable effects of mechanical and thermal treatments made on the coil; (iii) residual magnetization; and (iv) temperature variations during operation.
Conditional statistics for a passive scalar with a mean gradient and intermittency
Authors: Bourlioux A. , Majda A. J. , Volkov O.
Published: November 2006

The conditional dissipation and diffusion for a passive scalar with an imposed mean gradient are studied here. The results are obtained for an elementary model consisting of a random shear flow with a simple time-periodic transverse sweep. As the Peclet number is increased, scalar intermittency is observed; the scalar probability density function departs strongly from a Gaussian law. As a result, the conditional dissipation undergoes a transition from a quadratic behavior for the near-Gaussian probability distribution case at low Peclet number to a more complex shape at large Peclet. The conditional diffusion also undergoes a transition, this time from a linear to a nonlinear dependence, for cases with sufficient intermittency as well as a significant contribution from multiple spatial modes. The present analysis sheds some light on similar behaviors observed recently in numerical simulations of more complex models. The statistics in the present study are obtained by exact processing of one-dimensional quadrature results so that all sampling errors are eliminated, including in the tails of the distribution. This allows for a quantification of typical sampling errors when the conditional statistics are processed from numerical databases. The robustness of models based on polynomial fits for the conditional statistics is also assessed.
Effects of tip-gap size on the tip-leakage flow in a turbomachinery cascade
Authors: You Donghyun , Wang Meng , Moin Parviz , Mittal Rajat
Published: November 2006

The effects of tip-gap size on the tip-leakage vortical structures and velocity and pressure fields are investigated using large-eddy simulation, with the objective of providing guidelines for controlling tip-leakage cavitation and viscous losses associated with the tip-leakage flow. The effects of tip-gap size on the generation and evolution of the end-wall vortical structures are discussed by investigating their evolutionary trajectories and the mean velocity field. The tip-leakage jet and tip-leakage vortex are found to produce significant mean velocity gradients, leading to the production of vorticity and turbulent kinetic energy. Inside the cascade passage, the peak streamwise velocity deficit and magnitudes of vorticity and turbulent kinetic energy in the tip-leakage vortex are reduced as the tip-gap size decreases. The present analysis indicates that the mechanisms for the generation of vorticity and turbulent kinetic energy are mostly unchanged by the tip-gap size variation. However, larger tip-gap sizes are found to be more inductive to tip-leakage cavitation judged by the levels of negative mean pressure and pressure fluctuations.