bluuebunny/crossref_metadata_2025 huggingface dataset:
Cost analysis of Gamma Knife stereotactic radiosurgery
Authors: Griffiths Alison , Marinovich Luke , Barton Michael B. , Lord Sarah J.
Published: October 2007

Objectives: Stereotactic radiosurgery (SRS) is used to treat intracranial lesions and vascular malformations as an addition or replacement to whole brain radiotherapy and microsurgery. SRS can be delivered by hardware and software appended to standard linear accelerators (Linacs) or by dedicated systems such as Gamma Knife, which has been proposed as a more accurate and user friendly technology. Internationally, dedicated systems have been funded, despite limitations in evidence. However, some countries including Australia have not recommended additional reimbursement for dedicated systems. This study compares the costs of Linac radiosurgery with Gamma Knife radiosurgery.

Methods: Due to limited evidence on comparative effects, the economic analysis was restricted to a cost evaluation. The base-case analysis assumed a modified Linac was used only to treat SRS patients. However, because a modified Linac could be used to treat other radiotherapy patients, a second analysis assumed spare time was used to meet other radiotherapy needs, and Linac capital costs were apportioned according to SRS use.

Results: The incremental cost of Gamma Knife versus a modified Linac was estimated as AU$209 per patient. This result is sensitive to variations in assumptions. A second analysis proportioning capital costs according to SRS use showed that Gamma Knife may cost up to AU$1673 more per patient.

Conclusions: Gamma Knife may be cost competitive only if demand for SRS services is high enough to fully use equipment working time. However, given low patient demand and competing radiotherapy needs, Gamma Knife appears more costly and further evidence of survival or quality of life advantages may be required to justify reimbursement.
Setting the future policy agenda for health technology assessment: A specialty mapping approach
Authors: Shepherd Jonathan , Briggs Jackie , Payne Liz , Packer Claire , Kerridge Lynn , Ashton-Key Martin
Published: October 2007

Background: There is a need for innovative methodologies to identify and prioritize topics for health technology assessment (HTA). A pilot project to evaluate the methodology for specialty mapping was undertaken in the area of child and adolescent health. Two case studies are presented, in the area of sexually transmitted infections and acute pain.

Methods: The methodology comprised sequential stages, based on principles of systematic review. A “stakeholder model” encouraged wider participation. Key stages included identifying the topic area and setting the scope; developing a care pathway; searching for clinical guidelines/guidance, and evaluation literature; synthesis and mapping of literature to the “nodes” of the care pathway to highlight gaps; prioritizing the topics with stakeholders; and referring priorities to the appropriate agencies.

Results: A total of thirty guidelines/guidance documents and sixteen evaluation studies were mapped across the two case studies. In some nodes of the care pathway, more literature was mapped than others, suggesting important gaps in research and policy guidance. Sixty-two policy questions were identified and were rated by stakeholders in prioritization workshops. The highest priorities have been considered by senior committees for likely commissioning as research or guidelines/guidance.

Conclusions: This is one of the few published examples of innovative methodology to identify and prioritize topics for HTA. Specialty mapping can make a positive contribution to the policy agenda, with several research and policy gaps being fed into existing prioritization channels. Adequate time, resources, and capacity is required particularly in engaging stakeholders and developing a care pathway. Implementation of specialty mapping in other topic areas with on-going evaluation is recommended.
Non-finality and weight-sensitivity
Authors: Hyde Brett
Published: October 2007

This article presents a non-finality approach to weight-sensitivity, using constraints that prohibit stress on domain-final moras to account for phenomena where stress avoids light syllables. The issues addressed by the proposal include weight-sensitivity in unbounded stress systems, weight-sensitivity in generalised trochee systems, iambic lengthening, trochaic lengthening and minimal word restrictions. A non-finality approach improves the typological predictions for each of these phenomena and provides them with a general and uniform account, lending additional support for non-finality's central position in the theory.
Regional variation in the syntactic distribution of null finite complementizer
Authors: Kearns Kate
Published: October 2007

This article explores syntactic and regional variation in the choice between declarative (nonrelativizer)thatand zero complementizer. Using a corpus of contemporary prose from New Zealand, Australian, American, and British newspapers, the study examines complementizer choice in complements to verbs and adjectives, extraposed complements to verbs,it-subject constructions (It is obvious(that)), and copula constructions (The trouble is(that),It could be(that),What matters is(that),It was only later(that)). The form of the embedded subject (pronoun, short NP (noun phrase), long NP) is also taken into account. It is shown that significant regional differences in zero rates are to some extent syntactic. The New Zealand and Australian data show less inhibition of zero in clauses that are not adjacent to the clause-selecting lexical head than the American and British data.
Regional differences in low SES African-American children's speech in the school setting
Authors: Charity Anne H.
Published: October 2007

Comprehensive investigations of African-American Vernacular English (AAVE) have demonstrated that most features of AAVE reported in the sociolinguistic literature are consistently seen in nearly every African-American speech community in which vernacular speech has been documented. This article highlights quantitative regional differences in the speech produced by African-American children from three U.S. cities in an academic setting. In this analysis, 157 5- to 8-year-old African-American children in New Orleans, LA, Washington, DC, and Cleveland, OH imitated the sentences of a story presented in Standard American English (SAE) by teachers. The 15 sentences included many items that were possible mismatches between the child's vernacular and SAE. Afterwards, the children retold the story in their own words. Children's use of SAE and AAVE features in both tasks was analyzed. Higher rates of AAVE feature use occurred in New Orleans than in Cleveland or Washington, DC.
Appalachian English in southern Indiana? The evidence from verbal -s
Authors: José Brian
Published: October 2007

In this article, the variable use of verbal -swith (especially, third-person) plural subjects is examined in extreme south-central Indiana. The patterns observed are compared to the same in several varieties of Appalachian English, and it is argued that the local language variety reflects the morphosyntactic stability of the linguistic system brought here by pioneer settlers from various Appalachian states some 200 years before. A very small pilot-study corpus of comparable data from the extreme northwestern corner of Indiana is called on to help refute a “universalist” explanation for the similarities found in southern Indiana and Appalachia. Finally, the conditions surrounding the transplantation of Appalachian English to Kentuckiana and to other places (i.e., the Ozarks, North Carolina's Outer Banks) are considered, and questions are raised about the degree of isolation believed to be necessary in the respective communities.
‘In Italy we don’t have the means for illusion’: Grand opéra in nineteenth-century Bologna
Authors: NEWARK CORMAC
Published: October 2007

Contemporary press reports of two important stagings of grand opéra in Bologna – Rossini’s Guillaume Tell (as Rodolfo di Sterlinga) in 1840 and the Italian première of Verdi’s Don Carlos in 1867 – shed light on some intriguing details of the beginning and culmination of the genre’s reception in Italy. Through the prism of local civic pride, they illuminate not only the national standing of the composers in question and the state of regional operatic production, but also the political issues of the day as they impinged – frequently in unexpected ways – on then-current debates about musical style and genre. In particular, when read alongside the pronouncements of Angelo Mariani (conductor in Bologna from 1860) and, above all, Verdi, they reveal that the role, provenance and relative status of the works’ visual aspect (apparently so integral to the development of grand opéra) figured surprisingly importantly in the complicated and often contradictory discourse on unity in the nation at large.
Killing time: Contemporary representations of opera in British culture
Authors: WILSON ALEXANDRA
Published: October 2007

Recent debates about ‘high’ and ‘low’ culture and the perceived repositioning of such categories have had potentially profound implications for opera. British artist Sam Taylor-Wood’s video installation Killing Time (1994) provides a useful starting point from which to explore these polemics. By juxtaposing images of mundane daily life with a soundtrack drawn from Strauss’s Elektra, Taylor-Wood seems to present opera and ‘the everyday’ as irreconcilable. Yet, the perception of opera as highbrow has by no means been a historical constant in Britain. This article considers the extent to which opera may be regaining the ‘entertainment status’ it enjoyed for a period during the late nineteenth century, or whether its perception as an ‘elite’ product is more deeply ingrained in British culture than ever before. Killing Time’s critique of opera and the commentary it offers on voice, art as redemption, and the politics of participatory art are analysed and contrasted with the representation of opera in a more ‘popular’ medium, a reality television series in which members of the public were trained as opera singers. The article concludes that, while popular culture seems able to embrace opera, the more uneasy relationship today is that between opera and other forms of ‘high art’.
Feasibility of using retinol-binding protein from capillary blood specimens to estimate serum retinol concentrations and the prevalence of vitamin A deficiency in low-resource settings
Authors: Gorstein Jonathan L , Dary Omar , Pongtorn  , Shell-Duncan Bettina , Quick Tim , Wasanwisut Emorn
Published: October 2007

Vitamin A deficiency (VAD) is a significant public health problem in many countries. While cost-effective interventions are available to control VAD, reliable information is needed to the track progress of control programmes. However, assessment of VAD is uncommon because current approaches are expensive and not feasible in low-resource settings. The present study explores the utility of retinol-binding protein (RBP), analysed by enzyme-linked immunosorbent assay from capillary blood, as an alternative measure of serum retinol concentrations in populations. The study collected matched panels of venous and capillary blood from pre-school children in Chiang Mai, Thailand. Of a total sample of 195 children, there were no differences between RBP from venous blood, RBP from capillary blood or retinol from capillary blood relative to retinol from venous blood. Receiver-operating characteristic curve analysis suggested a cut-off of RBP < 0.825 μmol l−1had optimal screening proficiency relative to retinol <0.70 μmol l−1. For the purpose of population assessment, all three parameters performed well in screening for VAD relative to retinol from venous blood. There were no differences in the estimates of VAD between children stratified by inflammation status. Lower RBP concentrations were found in children in the early convalescent stage of infection than in children with no infection or in the late convalescent stage. This study provided evidence of the biological comparability between retinol and RBP estimated from venous blood and capillary blood. This is a critical observation as it provides empirical evidence that RBP from capillary blood is a surrogate measure of serum retinol concentrations.
Democratic Consolidation in East Asia
Authors: PARK CHONG-MIN
Published: October 2007

In this article, we attempt to describe how ordinary people in Japan, South Korea, and Taiwan view democracy and its authoritarian alternatives and how they experience institutional practices of their democracies to determine the extent of cultural and institutional democratization. The analysis of the 2006 AsiaBarometer Survey data shows that although the citizens of East Asian democracies unequivocally reject military authoritarian rule, they are ambivalent toward civilian authoritarian rule, and are not yet fully committed to democracy. The analysis also shows that they are not satisfied with the provision of civil rights and institutions of horizontal accountability, but remain highly satisfied with voting rights, which suggests that East Asian democracies are not adequately liberal, though unmistakably electoral, in the eyes of ordinary people. On the basis of this finding, we conclude that East Asian democracies fail to achieve a high-level equilibrium between the popular demand for democracy and the institutional supply of democracy.
Celebrating Patriotism: Carl Philipp Emanuel Bach’s Compositions for the Militia in Hamburg
Authors: RATHEY MARKUS
Published: October 2007

When Carl Philipp Emanuel Bach became cantor in Hamburg in 1768, he was faced with a long musical tradition shaped by his ancestor Georg Philipp Telemann. Part of this tradition was the provision of compositions for the annual meeting of the captains of the militia, for whom Telemann had composed several oratorios and serenades. Even though Bach composed only two such Bürgerkapitänsmusiken, they are instructive pieces, showing the relationship between music, culture and politics in late eighteenth-century Hamburg, which at the time was a centre of political discourse. Questions of democracy, the relationship between government and the individual, and the possibilities of ‘patriotic education’ were discussed earlier in Hamburg than in other regions of Germany. It is especially the question of patriotism and of patriotic behaviour that informs Bach’s Bürgerkapitänsmusiken. An analysis both of the librettos (written by Christian Wilhelm Alers) and of Bach’s music shows how the ideas of enlightened patriotic discourse lurk behind these compositions and how they aim to depict an ideal political community.
MUSIC IN THE AGE OF COFFEE
Authors: RICE JOHN A.
Published: October 2007

On 7–8 October 1791, about two months before his death, Mozart wrote to his wife: ‘Right after you left I played two games of billiards with Herr Mozart (who wrote the opera for Schikaneder’s theatre); then I sold my nag for 14 ducats; then I had Joseph summon Primus and bring me black coffee, with which I smoked a wonderful pipe of tobacco; then I orchestrated almost all of Stadler’s rondo’. In orchestrating the finale of the Clarinet Concerto under the influence of caffeine and nicotine, Mozart was very much a man of his age.
Die Kognitive Verhaltenstherapie der Zwangsstörungen
Authors: Wahl Karina , Hohagen Fritz , Kordon Andreas
Published: October 2007

Zusammenfassung: Die zentralen psychotherapeutischen Interventionen der kognitiven Verhaltenstherapie umfassen eine ausführliche Diagnostik und Bedingungsanalyse, die Entwicklung eines Entstehungs- und Aufrechterhaltungsmodells und - nach einer umfassenden kognitiven Vorbereitungsphase - schließlich eine intensive Übungsphase mit Expositionsübungen und Verhaltensexperimenten. Kognitive und verhaltenstherapeutische Elemente sind eng miteinander verwoben. Dysfunktionale, automatisch auftretende Fehlinterpretationen der Zwangsgedanken sowie langfristig bestehende hinderliche Grundannahmen werden sowohl durch Methoden der kognitiven Umstrukturierung auf der Gesprächsebene als auch durch gezielte Verhaltensexperimente und Expositionsübungen hinterfragt. Die klassische Exposition mit Habituationsrational wird somit ergänzt und eingebettet in eine systematische Hinterfragung hinderlicher Einstellungen. Ein besonderer Schwerpunkt liegt im weiteren Verlauf der Therapie auf dem Übergang ins Selbstmanagement mit dem Ziel, eigenständig Expositionen und Verhaltensexperimente zu entwerfen und anzuwenden.
Field relations between the spectral composition of ground motion and hydrological effects during the 1999 Chi‐Chi (Taiwan) earthquake
Authors: Wong Alexander , Wang Chi‐Yuen
Published: October 2007

The possibility that the frequency content of ground motion in earthquakes affects hydrological responses to earthquakes has yet to be extensively tested in the field. TheMw= 7.6 Chi‐Chi earthquake provided an opportunity to do so, as widespread liquefaction and groundwater level changes were recorded by instrumentation in the Choshui Alluvial Fan. Analysis of the resulting data shows that ground motion parameters that measure low‐frequency ground motions are more strongly correlated with coseismic groundwater level change and the occurrence of liquefaction than parameters that measure high‐frequency motions. Notably, horizontal peak ground acceleration, a metric often used to enumerate the strength of ground motion in liquefaction analysis, is weakly correlated with these hydrological effects. It is unclear from this analysis whether low‐frequency ground motion caused coseismic groundwater level change and liquefaction or whether the hydrological changes changed the spectral composition of the observed seismograms during the Chi‐Chi earthquake.
Liquid and magma viscosity in the anorthite‐forsterite‐diopside‐quartz system and implications for the viscosity‐temperature paths of cooling magmas
Authors: Getson Jacqueline M. , Whittington Alan G.
Published: October 2007

We measured the viscosity of 17 liquids in the systems anorthite‐forsterite‐quartz and anorthite‐diopside‐forsterite, representing analogs of dacitic, basaltic andesitic, and basaltic magmas. The three series lie in the anorthite liquidus fields and represent liquid lines of descent. The viscosity of evolving basaltic and basaltic andesite liquids changes little during cooling because the viscosity decrease associated with removal of polymerized anorthite component from the melt offsets the viscosity increase associated with cooling. A minimum liquidus viscosity in the basaltic system is encountered in the anorthite stability field. In contrast, dacitic liquids appear insensitive to the compositional changes during anorthite crystallization, and liquidus viscosity increases monotonically between anorthite and the anorthite‐forsterite‐quartz eutectic. Using the Einstein‐Roscoe equation to calculate the rheological effect of crystals, we show that magma viscosity always increases during crystallization for closed systems and that crystallinity is the dominant control on the viscosity of all three magma series. We introduce the concept of viscosity paths, which may approach one of four end‐members: (1) equilibrium crystallization (closed system) and (2) perfect fractional crystallization (open system) are both associated with changing residual liquid compositions; (3) supercooling without crystal growth maintains constant liquid composition, while (4) increasing crystallinity at constant liquid composition is only permissible for eutectic starting compositions. Because of the dependence of crystal‐liquid segregation rates on liquid viscosity and crystal buoyancy, feedback relations exist between evolving liquid composition, crystallinity, and magma viscosity. Crystal‐liquid segregation rates may increase or decrease during progressive cooling and crystallization of basaltic liquids.
Sensitivity of chemical tracers to meteorological parameters in the MOZART‐3 chemical transport model
Authors: Kinnison D. E. , Brasseur G. P. , Walters S. , Garcia R. R. , Marsh D. R. , Sassi F. , Harvey V. L. , Randall C. E. , Emmons L. , Lamarque J. F. , Hess P. , Orlando J. J. , Tie X. X. , Randel W. , Pan L. L. , Gettelman A. , Granier C. , Diehl T. , Niemeier U. , Simmons A. J.
Published: October 2007

The Model for Ozone and Related Chemical Tracers, version 3 (MOZART‐3), which represents the chemical and physical processes from the troposphere through the lower mesosphere, was used to evaluate the representation of long‐lived tracers and ozone using three different meteorological fields. The meteorological fields are based on (1) the Whole Atmosphere Community Climate Model, version 1b (WACCM1b), (2) the European Centre for Medium‐Range Weather Forecasts (ECMWF) operational analysis, and (3) a new reanalysis for year 2000 from ECMWF called EXP471. Model‐derived tracers (methane, water vapor, and total inorganic nitrogen) and ozone are compared to data climatologies from satellites. Model mean age of air was also derived and compared to in situ CO2 and SF6 data. A detailed analysis of the chemical fields simulated by MOZART‐3 shows that even though the general features characterizing the three dynamical sets are rather similar, slight differences in winds and temperature can produce substantial differences in the calculated distributions of chemical tracers. The MOZART‐3 simulations that use meteorological fields from WACCM1b and ECMWF EXP471 represented best the distribution of long‐lived tracers and mean age of air in the stratosphere. There was a significant improvement using the ECMWF EXP471 reanalysis data product over the ECMWF operational data product. The effect of the quasi‐biennial oscillation circulation on long‐lived tracers and ozone is examined.
Annual cycle of aerosol direct radiative effect over southeast Italy and sensitivity studies
Authors: Tafuro Anna Maria , Kinne Stefan , De Tomasi Ferdinando , Perrone Maria Rita
Published: October 2007

Aerosol direct radiative effect (DRE) calculations are presented to illustrate the annual cycle of the aerosol impact on the radiative energy balance of the Earth‐atmosphere system over southeast Italy. Meteorological parameters from radiosondes, aerosol vertical profiles by lidar, aerosol optical and microphysical properties by ground‐based Sun/sky photometry and satellite (MODIS) derived data of solar surface albedo, all referring to the 2003–2004 years, constitute the necessary input to radiative transfer simulations. The monthly evolution of both the solar and infrared aerosol direct radiative effect is examined at the top of the atmosphere (ToA), within the atmosphere and at the Earth's surface. Aside from cloud‐free conditions (clear‐sky), all‐sky conditions are also addressed by adopting ISCCP monthly products. Model results reveal a strong seasonality of the solar aerosol DRE for southeast Italy, which is mainly driven by the available sunlight, but it is also modulated by variations in aerosol properties. Under cloud‐free conditions, winter aerosol DREs are within −(6 ± 2) W/m2 at the ToA and −(7 ± 2) W/m2 at the surface, while summer aerosol DREs are within −(9 ± 1) W/m2 at the ToA and −(15 ± 3) W/m2 at the surface. The larger difference in summer indicates that the heating of the aerosol layer (atmospheric forcing) is much stronger in summer and actually largest in early fall. Under all‐sky conditions the solar aerosol direct radiative effect decreases to −(4 ± 1) W/m2 and −(3 ± 1) W/m2 in winter and to −(12 ± 3) W/m2 and −(7 ± 1) W/m2 in summer, at surface and ToA, respectively. Model results also reveal that solar aerosol DREs dominates infrared aerosol DREs. The performed sensitivity studies demonstrate the relatively weak impact of meteorological parameters and aerosol vertical profiles and the strong impact of solar surface albedo values. Finally, it is shown that the simulated all‐sky aerosol DRE at the surface is consistent with radiometer measurements.
El Niño–Southern Oscillation–based index insurance for floods: Statistical risk analyses and application to Peru
Authors: Khalil Abedalrazq F. , Kwon Hyun‐Han , Lall Upmanu , Miranda Mario J. , Skees Jerry
Published: October 2007

Index insurance has recently been advocated as a useful risk transfer tool for disaster management situations where rapid fiscal relief is desirable and where estimating insured losses may be difficult, time consuming, or subject to manipulation and falsification. For climate‐related hazards, a rainfall or temperature index may be proposed. However, rainfall may be highly spatially variable relative to the gauge network, and in many locations, data are inadequate to develop an index because of short time series and the spatial dispersion of stations. In such cases, it may be helpful to consider a climate proxy index as a regional rainfall index. This is particularly useful if a long record is available for the climate index through an independent source and it is well correlated with the regional rainfall hazard. Here El Niño–Southern Oscillation (ENSO) related climate indices are explored for use as a proxy to extreme rainfall in one of the districts of Peru, Piura. The ENSO index insurance product may be purchased by banks or microfinance institutions to aid agricultural damage relief in Peru. Crop losses in the region are highly correlated with floods but are difficult to assess directly. Beyond agriculture, many other sectors suffer as well. Basic infrastructure is destroyed during the most severe events. This disrupts trade for many microenterprises. The reliability and quality of the local rainfall data are variable. Averaging the financial risk across the region is desirable. Some issues with the implementation of the proxy ENSO index are identified and discussed. Specifically, we explore (1) the reliability of the index at different levels of probability of exceedance of maximum seasonal rainfall, (2) the effect of sampling uncertainties and the strength of the proxy's association to local outcome, (3) the potential for clustering of payoffs, (4) the potential that the index could be predicted with some lead time prior to the flood season, and (5) evidence for climate change or nonstationarity in the flood exceedance probability from the long ENSO record.
Impact of anthropogenic combustion emissions on the fractional solubility of aerosol iron: Evidence from the Sargasso Sea
Authors: Sedwick Peter N. , Sholkovitz Edward R. , Church Thomas M.
Published: October 2007

We report empirical estimates of the fractional solubility of aerosol iron over the Sargasso Sea during periods characterized by high concentrations of Saharan dust (summer 2003) and by low concentrations of aerosols in North American/maritime North Atlantic air masses (spring 2004 and early summer 2004). We observed a strong inverse relationship between the operational solubility of aerosol iron (defined using a flow‐through deionized‐water leaching protocol) and the total concentration of aerosol iron, whereby the operational solubility of aerosol iron was elevated when total aerosol iron loadings were low. This relationship is consistent with source‐dependent differences in the solubility characteristics of our aerosol samples and can be described by a simple mixing model, wherein bulk aerosols represent a conservative mixture of two air mass end‐members that carry different aerosol types: “Saharan air,” which contains a relatively high loading of aerosol iron (27.8 nmol Fe m−3) that has a low fractional solubility (0.44%), and “North American air,” which contains a relatively low concentration of aerosol iron (0.5 nmol Fe m−3) that has a high fractional solubility (19%). Historical data for aerosols collected on Bermuda indicate that the low iron loadings associated with North American air masses are typically accompanied by elevated V/Al, Fe/Al, and V/Mn mass ratios in the bulk aerosol, relative to Saharan dust, which are indicative of anthropogenic fuel‐combustion products. The identification of similar compositional trends in our Sargasso Sea aerosol samples leads us to suggest that the elevated solubility of iron in the aerosols associated with North American air masses reflects the presence of anthropogenic combustion products, which contain iron that is readily soluble relative to iron in Saharan soil dust. We thus propose that the source‐dependent composition of aerosol particles (specifically, the relative proportion of anthropogenic combustion products) is a primary determinant for the fractional solubility of aerosol iron over the Sargasso Sea. This hypothesis implies that anthropogenic combustion emissions could play a significant role in determining the atmospheric input of soluble iron to the surface ocean.
Dissolution effects on the crystallography and Mg/Ca content of planktonic foraminifera Globorotalia tumida (Rotaliina) revealed by X‐ray diffractometry
Authors: Nouet Julius , Bassinot Franck
Published: October 2007

Several authors suggested that the thinning, with increasing depth of deposition, of calcite X‐ray diffractometry (XRD) peaks obtained on planktonic foraminifera tests resulted from the preferential removal of their poorly crystallized parts as dissolution increases. By deconvolving XRD peak (104) from Globorotalia tumida (surface sediments, Sierra Leone Rise depth transect), we show that the full width at midheight does not depend only upon crystallinity, but reflects also the chemical and structural heterogeneity of foraminifera tests, which results in closely spaced, individual (104) diffraction peaks corresponding to phases with slightly different Mg contents. G. tumida contains two calcite phases: a well crystallized, Mg‐poor calcite and a poorly crystallized, Mg‐richer calcite. Increasing dissolution results in the preferential removal of the Mg‐richer calcite and the improvement of its crystallinity, whereas the Mg‐poor calcite does not seem to be affected by dissolution between 2750 m and 4950 m of water depth on Sierra Leone Rise.
Nd isotopic constraints on the origin of suspended particles in the Atlantic Sector of the Southern Ocean
Authors: Hegner E. , Dauelsberg H. J. , Rutgers van der Loeff M. M. , Jeandel C. , de Baar H. J. W.
Published: October 2007

In the nutrient‐rich Southern Ocean, Fe is a vital constituent controlling the growth of phytoplankton. Despite much effort, the origin and transport of Fe to the oceans are not well understood. In this study we address the issue with geochemical data and Nd isotopic compositions of suspended particle samples collected from 1997 to 1999 in the South Atlantic Sector of the Southern Ocean. Al, Th, and rare earth element (REE) concentrations as well as 143Nd/144Nd isotopic ratios in acetic acid‐leached particle samples representing the lithogenic fraction delineate three major sources: (1) Patagonia and the Antarctic Peninsula provide material with ɛNd > −4 that is transported toward the east with the polar and subpolar front jets, (2) the south African shelf, although its influence is limited by the circumpolar circulation and wind direction, can account for material with ɛNd of −12 to −14 adjacent to South Africa, and (3) East Antarctica provides material with ɛNd of −10 to −15 to the eastern Weddell Sea and adjacent Antarctic Circumpolar Current. For this region we interpret the Nd isotopic evidence in combination with oceanographic/atmospheric constraints as evidence for supply of significant amounts of terrigenous detritus by icebergs.
Bathymetry of the Amundsen Sea continental shelf: Implications for geology, oceanography, and glaciology
Authors: Nitsche F. O. , Jacobs S. S. , Larter R. D. , Gohl K.
Published: October 2007

The Amundsen Sea continental shelf is one of the most remote areas of coastal Antarctica and was relatively unexplored until the late 1980s. Over the last two decades, increased oceanographic and geological interest has led to several cruises that resulted in sufficient bathymetric data to compile a fairly detailed regional map of the Amundsen continental shelf. We have combined available multibeam and single‐beam bathymetry data from various sources and created a new regional bathymetry of the Amundsen Sea continental shelf and margin. Deep trough systems that dominate the inner shelf are aligned with present glaciers and separated by shallower ridges. Shaped by paleo‐ice streams, these features merge into a small number of broader troughs on the middle shelf and shoal seaward. They now serve as conduits and reservoirs for relatively warm Circumpolar Deep Water. This new compilation is a major improvement over previously available regional maps and should aid the numerical modeling of ocean circulation, the reconstructions of paleo‐ice streams, and the refinement of ice sheet models.
Crustal motion in the zone of the 1960 Chile earthquake: Detangling earthquake‐cycle deformation and forearc‐sliver translation
Authors: Wang Kelin , Hu Yan , Bevis Michael , Kendrick Eric , Smalley Robert , Vargas Rodrigo Barriga , Lauría Eduardo
Published: October 2007

Temporary deformation in great earthquake cycles and permanent shear deformation associated with oblique plate convergence both provide critical clues for understanding geodynamics and earthquake hazard at subduction zones. In the region affected by the Mw 9.5 great Chile earthquake of 1960, we have obtained GPS observations that provide information on both types of deformation. Our velocity solutions for the first time span the entire latitudinal range of the 1960 earthquake. The new observations revealed a pattern of opposing (roughly arc‐normal) motion of coastal and inland sites, consistent with what was reported earlier for the northern part of this region. This finding supports the model of prolonged postseismic deformation as a result of viscoelastic stress relaxation in the mantle. The new observations also provide the first geodetic evidence for the dextral motion of an intravolcanic arc fault system and the consequent northward translation of a forearc sliver. The sliver motion can be modeled using a rate of 6.5 mm/a, accommodating about 75% of the margin‐parallel component of Nazca–South America relative plate motion, with the rate diminishing to the north. Furthermore, the new GPS observations show a southward decrease in margin‐normal velocities of the coastal area. We prefer explaining the southward decrease in terms of changes in the width or frictional properties of the megathrust seismogenic zone. Because of the much younger age of the subducting plate and warmer thermal regime in the south, the currently locked portion of the plate interface may be narrower. Using a three‐dimensional viscoelastic finite element model of postseismic and interseismic deformation following the 1960 earthquake, we demonstrate that this explanation, although not unique, is consistent with the GPS observations to the first order.
Plasma environment in the wake of Titan from hybrid simulation: A case study
Authors: Modolo R. , Chanteur G. M. , Wahlund J.‐E. , Canu P. , Kurth W. S. , Gurnett D. , Matthews A. P. , Bertucci C.
Published: October 2007

On 26 December 2005, the Cassini spacecraft flew through Titan's plasma wake and revealed a complex and dynamic region. Observations suggest a strong asymmetry which seems to be displaced from the ideal position of the wake. Two distinct plasma regions are identified with a significant difference on the electron number density and on the plasma composition. Simulation results using a three‐dimensional and multi‐species hybrid model, performed in conditions similar to those encountered during the flyby, are presented and compared to the observations. An acceptable agreement is shown between the model predictions and the observations. We suggest that the observed asymmetries, in terms of density and plasma composition, are mainly caused by the a combination of the asymmetry in the ion/electron production rate and the magnetic field morphology, where the first plasma region is connected to the dayside hemisphere of Titan's ionosphere while the other is connected to the nightside hemisphere.
A year of microseisms in southern California
Authors: Gerstoft Peter , Tanimoto Toshiro
Published: October 2007

Microseisms are due to continuous harmonic forcing by ocean waves, whose sources vary in time, frequency, and azimuth. Using frequency‐domain array beamforming, this variation is studied using one‐year of continuous seismic data from 155 stations in southern California. Detailed analysis of data delineates spatiotemporal variations of sources for the primary and secondary microseisms. Both types of microseisms are generated near the coasts but the locations of excitation are different and change with season. Often sources are multiply located but can be spread out over wider areas, especially in the case of secondary microseisms. Distant storms can also be seen occasionally in the frequency range between the primary and secondary microseisms where spectral amplitudes from nearby sources are low.
Sampling techniques in high‐dimensional spaces for the development of satellite remote sensing database
Authors: Aires Filipe , Prigent Catherine
Published: October 2007

This study presents various strategies to sample databases from large atmospheric data sets in high‐dimensional spaces for satellite remote sensing applications. In particular, two sampling algorithms are examined: the traditional uniform sampling that lists all possible situations and the clustering sampling (K‐means) that respects the natural variability probability distribution functions. In order to assess the quality of both sampling methods, the extracted databases are used to extract first guesses for satellite remote sensing schemes. They are also employed as training databases for the calibration of statistical retrieval algorithms. The analysis of these sampling algorithms is illustrated by constructing both a first guess (FG) extraction and a retrieval databases of temperature and water vapor profiles over sea for the Atmospheric Microwave Sounding Unit (AMSU) instrument. The advantages and problems of each sampling approach are thoroughly examined and sensitivity studies are conducted to analyze the impact on the FG extraction and retrieval of various algorithmic parameters such as the distance being used, the size of the databases, or the instrumental noise sensitivity. The K‐means clustering algorithm, not yet used for this kind of problems, is very efficient compared to the more traditional uniform sampling approach. It is also shown that it is important to have quasi‐automatic and flexible tools that can be used to generate problem‐specific databases.
Analysis of the first gigantic jet recorded over continental North America
Authors: van der Velde Oscar A. , Lyons Walter A. , Nelson Thomas E. , Cummer Steven A. , Li Jingbo , Bunnell James
Published: October 2007

Two low‐light cameras near Marfa, Texas, recorded a gigantic jet over northern Mexico on 13 May 2005 at approximately 0423:50 UTC. Assuming that the farthest of two candidate storm systems was its source, the bright lower channel ended in a fork at around 50–59 km height with the very dim upper branches extended to 69–80 km altitude. During the time window containing the jet, extremely low frequency magnetic field recordings show that there was no fast charge moment change larger than 50 coulomb times kilometers (C km) but there was a larger and slower charge moment change of 520 C km over 70 ms. The likely parent thunderstorm was a high‐precipitation supercell cluster containing a persistent mesocyclone, with radar echo tops of at least 17 km. However, photogrammetric analysis suggests that the gigantic jet occurred over the forward flank downdraft region with echo tops of 14 km. This part of the supercell may have had an inverted‐polarity charge configuration as evidenced by positive cloud‐to‐ground lightning flashes (+CG) dominating over negative flashes (−CG), while −CGs occurred under the downwind anvil. Four minutes before the gigantic jet, −CG activity practically ceased in this area, while +CG rates increased, culminating during the 20 s leading up to the gigantic jet with four National Lightning Detection Network–detected +CGs. A relative lull in lightning activity of both polarities was observed for up to 1.5 min after the gigantic jet. The maturing storm subsequently produced 30 sprites between 0454 and 0820 UTC, some associated with extremely large impulse charge moment change values.
Variability in surface‐subsurface hydrologic interactions and implications for nutrient retention in an arid‐land stream
Authors: Dent C. Lisa , Grimm Nancy B. , Martí Eugènia , Edmonds Jennifer W. , Henry Julia Curro , Welter Jill R.
Published: October 2007

Hydrologic interactions among biogeochemically active stream subsystems affect material export downstream. We combined a conservative tracer addition with measurements of water table elevation and nutrient concentrations of surface and subsurface water to examine hydrologic interactions among surface and subsurface subsystems and their implications for stream biogeochemistry. We injected bromide (Br−) into a 400‐m reach of Sycamore Creek, a losing stream in central Arizona, for 15 d and monitored changes in concentration in three subsystems: surface, parafluvial, and riparian zones. Additionally, we collected water samples from these subsystems for nutrient analyses. Water flowed from surface to subsurface zones as expected in this losing stream, but a significant amount of subsurface water (17% of surface discharge in the reach) returned to the surface. Within the parafluvial subsystem, median transport time (Tmed) in two gravel bars differed substantially (from 2 to 30 h and from 6 to >300 h, respectively, for upper and lower bars), and varied significantly with depth in the lower bar (mean (±se) Tmed = 190 ± 20 h at 30 cm compared to 101 ± 18 h at 110 cm). Flow paths from the surface to parafluvial and riparian zones, and subsequently back to the surface stream, differ from patterns in mesic areas, where water moves laterally and vertically towards the surface stream. Estimates of nutrient retention for the stream reach varied four fold in response to simulated changes in lateral subsurface connections and the configuration of subsystems. Thus at this scale, accurate nutrient budgets require an understanding of surface‐subsurface connections and hydrologic parameters.
Marginal methods of intensity‐duration‐frequency estimation in scaling and nonscaling rainfall
Authors: Veneziano Daniele , Lepore Chiara , Langousis Andreas , Furcolo Pierluigi
Published: October 2007

Practical methods for the estimation of the intensity‐duration‐frequency (IDF) curves are usually based on the observed annual maxima of the rainfall intensityI(d) in intervals of different durationd. Using these historical annual maxima, one estimates the IDF curves under the condition that the rainfall intensity in an interval of durationdwith return periodTis the product of a functiona(T) ofTand a functionb(d) ofd(separability condition). Various parametric or semiparametric assumptions ona(T) andb(d) produce different specific methods. As alternatives we develop IDF estimation procedures based on the marginal distribution ofI(d). If the marginal distribution scales in a multifractal way withd, this condition can be incorporated. We also consider hybrid methods that estimate the IDF curves using both marginal and annual maximum rainfall information. We find that the separability condition does not hold and that the marginal and hybrid methods perform better than the annual maximum estimators in terms of accuracy and robustness relative to outlier rainfall events. This is especially true for long return periods and when the length of the available record is short. Marginal and hybrid methods produce accurate IDF estimates also when only a few years of continuous rainfall data are available.
Dopamine
Authors: Bannon Michael J
Published: October 2007

Dopamine acts as a neurotransmitter, or chemical messenger, between cells in the brain and elsewhere, in a variety of organisms from simple invertebrates to humans. It exerts an important influence on many aspects of brain functioning, from control of movement to higher cognitive processes.
Electronic transport through molecular junctions with nonrigid molecule-leads coupling
Authors: Caspary Toroker Maytal , Peskin Uri
Published: October 2007

The Landauer-type formulation of current through a molecular junction with electronic-nuclear coupling introduced by Troisi et al. [J. Chem. Phys. 118, 6072 (2003)] is generalized to account for the dependence of the molecule-leads coupling terms on the nuclear coordinates. Although this electronic-nuclear coupling is external to the molecule there is no need to extend the molecular subspace when projection operators are employed for calculations of the current through the junction. A test case of a conductor with vibrating contacts to the leads is studied numerically. It is demonstrated that contact vibrations lead to inelastic contributions to the current and to characteristic features in the I-V curve and its derivatives, similar to the ones observed for internal (molecular) electronic-nuclear coupling.
Argon nucleation in a cryogenic nucleation pulse chamber
Authors: Iland Kristina , Wölk Judith , Strey Reinhard , Kashchiev Dimo
Published: October 2007

Homogeneous nucleation of argon droplets has been measured with a newly designed cryogenic nucleation pulse chamber presented already in a previous paper [Fladerer and Strey, J. Chem. Phys. 124, 16 (2006)]. Here we present the first systematic nucleation onset data for argon measured in a temperature range from 42to58K and for vapor pressures from 0.3to10kPa. For these data we provide an analytical fit function. From the geometry of the optical detection system and the time of nucleation the experimental nucleation-rate range can be estimated. This allows a comparison of the data with the predictions of classical nucleation theory. We found 16–26 orders of magnitude difference between theory and experiment, and a too strong theoretical dependence of the nucleation rate on temperature. A comparison with the self-consistent theory of Girshick and Chiu [J. Chem. Phys. 93, 1273 (1990)] showed improved temperature dependence but still discrepancies of 11–17 orders of magnitude compared to experimental data. The thermodynamically consistent theory of Kashchiev [J. Chem. Phys. 118, 1837 (2003)] was found to agree rather well with experiment in respect to the temperature dependence and to predict rates about 5-7 orders of magnitude below the experimental ones. With the help of the Gibbs-Thomson equation we were able to evaluate the size of the critical nucleus to be 40–80 argon atoms.
On implicit subgrid-scale modeling in wall-bounded flows
Authors: Hickel S. , Adams N. A.
Published: October 2007

Approaches to large eddy simulation where subgrid-scale model and numerical discretization are fully merged are called implicit large eddy simulation (ILES). Recently, we have proposed a systematic framework for development, analysis, and optimization of nonlinear discretization schemes for ILES [Hickel et al., J. Comput. Phys. 213, 413(2006)]. The resulting adaptive local deconvolution method (ALDM) provides a truncation error which acts as a subgrid-scale model consistent with asymptotic turbulence theory. In the present paper ALDM is applied to incompressible, turbulent channel flow to analyze the implicit model for wall-bounded turbulence. Computational results are presented for Reynolds numbers, based on friction velocity and channel half-width, of Reτ=180, Reτ=395, Reτ=590, and Reτ=950. All simulations compare well with direct numerical simulation data and yield better results than the dynamic Smagorinsky model at the same resolution. The results demonstrate that the implicit model ALDM provides an accurate prediction for wall-bounded turbulence although model parameters have been calibrated for the infinite Reynolds number limit of isotropic turbulence. The near-wall accuracy can be further improved by a simple modification which is described in the paper.