bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on rhomb shoulders in packaging machines
Authors: Zhou Yi‐Jie , Wang Zhi‐Wei
Published: October 2004

The mathematical description of a rhomb shoulder is presented, and the equations of the bending curve, the shoulder curved surface and the fringe curve are developed. The round shoulder is also discussed as a special case of rhomb shoulder. To confirm the validity of the present mathematical description, and furthermore to give the modern methods of the design and manufacturing of the shoulder, a 3‐D rhomb shoulder is modelled on computer by using the present mathematical description, and an actual rhomb shoulder is manufactured by rapid manufacturing machine. Copyright © 2004 John Wiley & Sons, Ltd.
Energies of organic molecules and atoms in density functional theory
Authors: Csonka Gábor I. , Ruzsinszky Adrienn , Tao Jianmin , Perdew John P.
Published: October 2004

In the assessment of density functional approximations for the exchange‐correlation energy, great weight is usually given to the accuracy of molecular atomization energies, or the enthalpies of formation constructed from calculated atomization energies. Here we show that a recent nonempirical functional, the meta‐generalized gradient approximation of Tao, Perdew, Staroverov, and Scuseria, achieves remarkably accurate atomization energies even for the larger organic molecules of the G3‐3 test set. But we also present strong evidence that most of the error of previous nonempirical functionals resides in the energy of the free atom and so cancels out of typical reaction energies. Finally, we suggest that enthalpies of formation calculated without any reference to the free atoms would provide a fairer assessment of the performance of approximate density functionals. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
DFT study of polarizabilities and dipole moments of water clusters
Authors: Yang M. , Senet P. , Van Alsenoy C.
Published: October 2004

Density functional theory (DFT) calculations with different exchange‐correlation functionals, Becke's three‐parameter exchange functional and the gradient‐corrected functional of Lee, Yang, and Paar (B3LYP) and Becke's three‐parameter functional with Perdew–Wang correlational functional (B3PW91), are performed to study the dielectric properties of small and medium‐sized water clusters. For these H‐bonded systems, we optimize the geometries and compute the dipole moments and polarizabilities using a supermolecule approach. The corresponding properties of the individual water molecules in the clusters are extracted from the molecular properties using the Hirshfeld expansion of the electronic density. Calculations at Hartree–Fock and second‐order Møller–Plesset (MP2) levels are also presented for a comparison with the DFT results. The dependence of the dielectric properties on the cluster structure and size is given for both clusters and individual molecules and is compared with the available experimental data. The intermolecular interactions and their influences on the dielectric properties are discussed. The current results could serve to improve existing polarizable force fields for water. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Photoelectron resonance capture ionization mass spectrometry: a soft ionization source for mass spectrometry of particle‐phase organic compounds
Authors: LaFranchi Brian W. , Zahardis James , Petrucci Giuseppe A.
Published: October 2004

Photoelectron resonance capture ionization (PERCI) is a soft and sensitive ionization method, based on the attachment of low‐energy (<1 eV) photoelectrons to organic analyte molecules. PERCI has been developed in our laboratory for the real‐time analysis of organic particles by mass spectrometry, and is employed here to monitor the heterogeneous reaction of ozone with oleic acid. Simplified identification of the reaction products is possible as a result of the soft nature of PERCI, giving predominantly the [MH]− ions. The major particle‐phase products are identified as: 1‐nonanal, nonanoic acid, 9‐oxononanoic acid, and azelaic acid, consistent with proposed mechanisms. New insight into this well‐studied heterogeneous reaction is gained as additional minor particle‐phase products, consistent with the Criegee mechanism, are readily detected. Copyright © 2004 John Wiley & Sons, Ltd.
Tissue and fixative dependent shifts of δ13C and δ15N in preserved ecological material
Authors: Sweeting C. J. , Polunin N. V. C. , Jennings S.
Published: October 2004

Carbon and nitrogen stable isotope analyses are routinely used to investigate aquatic food webs, and have potential application in retrospective investigations using archived materials. However, such analyses assume that storage does not alter isotopic signatures of materials preserved, or that changes in isotopic composition during storage are predictable. Here we examine preservation shifts on cod (Gadus morhua) muscle, roe and liver tissue over 21 months following preservation in 80% ethanol, in 4% formaldehyde, and by freezing. Preservation shifts were not consistent among tissues. High protein tissues exhibited greater δ15N shifts than low protein tissues in 4% formaldehyde, while greater δ13C shifts occurred in relatively higher fat tissues when preserved in alcohol. Freezing did not change isotopic signatures. Responses of δ15N and δ13C are explained by differences in the preservative's isotopic signature and the reaction properties and biochemical composition of the tissues preserved. The results clarify some of the processes that lead to isotopic change during preservation. Copyright © 2004 John Wiley & Sons, Ltd.
TAPping into argumentation: Developments in the application of Toulmin's Argument Pattern for studying science discourse
Authors: Erduran Sibel , Simon Shirley , Osborne Jonathan
Published: October 2004

This paper reports some methodological approaches to the analysis of argumentation discourse developed as part of the two‐and‐a‐half year project titled “Enhancing the Quality of Argument in School Scienc'' supported by the Economic and Social Research Council in the United Kingdom. In this project researchers collaborated with middle‐school science teachers to develop models of instructional activities in an effort to make argumentation a component of instruction. We begin the paper with a brief theoretical justification for why we consider argumentation to be of significance to science education. We then contextualize the use of Toulmin's Argument Pattern in the study of argumentation discourse and provide a justification for the methodological outcomes our approach generates. We illustrate how our work refines and develops research methodologies in argumentation analysis. In particular, we present two methodological approaches to the analysis of argumentation resulting in whole‐class as well as small‐group student discussions. For each approach, we illustrate our coding scheme and some results as well as how our methodological approach has enabled our inquiry into the quality of argumentation in the classroom. We conclude with some implications for future research in argumentation in science education. © 2004 Wiley Periodicals, Inc. Sci Ed 88:915–933, 2004
Analysis and improvement of HITS algorithm for detecting Web communities
Authors: Nomura Saeko , Oyama Satoshi , Hayamizu Tetsuo , Ishida Toru
Published: October 2004

This paper discusses Kleinberg's HITS algorithm (hyperlink‐induced topic search) that extracts the Web community by Web inherent hyperlink analysis. The problems of the algorithm are analyzed and an improvement is proposed. For this purpose, a tool (Link Viewer) that visualizes the operation process of HITS algorithm was developed. The analysis revealed the following problem of the HITS algorithm: when there exists a page in the base set which is not related to the original topic at all and has a dense link structure, it is impossible to extract the Web community (authority and hub) matched to the original topic (topic drift problem). The authors focused only on the link analysis, and proposed the following modifications: (1) a technique in the eigenvalue calculation to consider the projection on the root subspace; (2) a technique for iterative calculation by extracting only the page from the base set which has link relations to multiple pages in the root set. A technique combining (1) and (2) is also considered. As a result, the topic drift problem is avoided for any topic with a relatively small amount of computation, and the HITS algorithm is improved by using the link information. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(13): 32–42, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10425
A test circuit for pin shorts generating oscillation in CMOS logic circuits
Authors: Ichimiya Masahiro , Hashizume Masaki , Yotsuyanagi Hiroyuki , Tamesada Takeomi
Published: October 2004

When a CMOS logic IC is soldered on a printed circuit board, a pin short may occur. When the fault is excited, logical oscillation may be generated at the location where the fault occurs. In this paper, the authors propose a test method based on supply current of a logic circuit and a test circuit to detect a fault in the logic circuit that generates logical oscillation. They show by some experiments that a fault that generates oscillation when the fault is excited will be detected with the test circuit. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(13): 10–20, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10604
Lean product development flow
Authors: Oppenheim Bohdan W.
Published: October 2004

A general holistic framework, also called a process—named “Lean Product Development Flow (LPDF)”—for organizing the engineering work of Product Development (PD), has been proposed as a contribution to the emerging field of Lean Systems Engineering. The framework is based on Lean Principles, with emphasis on PD value‐pulling workflow pulsed by takt periods. The value is defined as (1) mission assurance/product quality, (the traditional goals of Systems Engineering) and (2) reduced program cost and schedule achieved by a radical reduction of waste. LPDF is recommended for smaller design programs based on a high degree of legacy knowledge, with technologies mature enough so that the program feasibility is not in question. LPDF may involve limited‐scope research, provided that it can be identified early in the program, and carried out separate from the main workflow. The paper is focused on aerospace and defense programs, which are presently burdened with as much as 60–90% of waste, but the process is also applicable to commercial programs. LPDF can be applied to the entire PD, to one or more milestones, and to a multilevel program. LPDF requires both detailed preparations and disciplined execution. The preparations include detailed Value Stream Mapping, separation of research from the main workflow, parsing of the Value Stream map into Takt Periods, architecting the LPDF team using dynamic allocation of resources, and team training. LPDF execution is organized as a flow through a series of short and equal work Takt Periods, each followed by an Integrative Event for structured, comprehensive coordination. Strategic and flexible tactical mitigations of uncertainties must be applied during the flow. LPDF also requires excellent leadership of a Chief Engineer, modeled after Toyota and Honda, who is a dedicated program “owner,” an expert systems designer, a strong leader focused on the program and product integrity, and skilled in consensus‐building. The Chief Engineer is responsible for the entire program, with Assistant Chiefs assisting in selected technical areas, and a Project Manager assisting with program administration. An industrial pilot program is currently being undertaken to validate the method. © 2004 Wiley Periodicals, Inc. Syst Eng 7: 352–376, 2004
Audit on nuchal translucency thickness measurements in Flanders, Belgium: a plea for methodological standardization
Authors: Gyselaers W. J. A. , Vereecken A. J. , Van Herck E. J. H. , Straetmans D. P. L. , de Jonge E. T. M. , Ombelet W. U. A. M. , Nijhuis J. G.
Published: October 2004

Objectives

To audit nuchal translucency thickness (NT) measurements for fetal aneuploidy screening in Flanders, and to estimate the impact of small variations in NT measurement on the screening result of two first‐trimester screening algorithms: maternal age + NT (Algorithm A), and maternal age + NT + pregnancy associated plasma protein‐A + free β‐human chorionic gonadotropin (Algorithm B).

Methods

We used the database of first‐trimester combined screening, as collected by the General Medical Laboratory AML in Antwerp, Belgium, between 1 January 2001 and 1 April 2004. Audit was performed by establishing a delta‐NT distribution curve for one trainee of The Fetal Medicine Foundation (FMF) and for a group of 263 other sonographers, in comparison with the FMF reference values. Risks for fetal aneuploidy were calculated at a cut‐off value of 1 : 300 for Algorithm A and 1 : 150 for Algorithm B. These risks were recalculated in both algorithms after a modeled increase of all NT values by 0.1 or 0.2 mm.

Results

In a total of 592 measurements performed by the FMF trainee, the 5th, 50th and 95th percentiles of delta‐NT measurements were at −0.41, +0.03 and +0.68 mm, respectively. These values were close to the FMF reference values. The screen‐positive rate for this set of data was 4.4% (26/592) in both algorithms. For the 12 555 measurements of the 263 other sonographers, the 5th, 50th and 95th percentiles of delta‐NT were at −0.81, −0.14 and +0.73 mm, respectively, which clearly indicates underestimation of NT in the lower range. In this set of data the screen‐positive rate was 3.5% for both algorithms (439/12 555 for Algorithm A and 436/12 555 for Algorithm B). Also in this group, 5% (59/1186) of negative screening results at maternal age ≥ 35 years in Algorithm A became positive after a modeled 0.1‐mm increase in NT, whereas this was only in 1.2% (134/11 369) of tests at maternal age < 35 years (P < 0.0001). The overall increase of screen‐positive rate in Algorithm A after an NT modification of +0.1 mm was 1.2% (152/12 555), significantly more than in Algorithm B (86/12 555; 0.7%) (P < 0.0001).

Conclusion

In Flanders, there is a systematic underestimation of NT in comparison with the FMF reference range. Attempts to change these measurements according to the FMF criteria are crucial. This will mainly influence the screening results of women at advanced maternal age and of NT‐based algorithms without the use of other parameters. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Geochronology of age‐progressive volcanism of the Oregon High Lava Plains: Implications for the plume interpretation of Yellowstone
Authors: Jordan Brennan T. , Grunder Anita L. , Duncan Robert A. , Deino Alan L.
Published: October 2004

The High Lava Plains province (HLP) is a late Cenozoic bimodal volcanic field at the northern margin of the Basin and Range province in southeastern Oregon that hosts a westward younging trend of silicic volcanism that crudely mirrors northeastward migration of silicic volcanism along the Yellowstone–Snake River Plain (YSRP) trend. We present 40Ar/39Ar ages for 19 rhyolite domes, 5 rhyolite ash flow tuffs, and 34 basaltic lavas from the HLP. The previously identified trend of westward migration of HLP rhyolites is confirmed. The rate of propagation is ∼33 km/m.y. from 10 to 5 Ma, slowing to ∼13 km/m.y. after 5 Ma. The duration of silicic volcanism at any locus is ∼2 m.y. Three older HLP dacite domes yielded ages of ∼15.5 Ma. Basalts are not age progressive. We identify several episodes of increased basaltic activity at 7.5–7.8, 5.3–5.9, and 2–3 Ma, with the younger episode likely continuing into the Recent. The HLP and YSRP trends emerged from the axis of middle Miocene basaltic volcanism of the Columbia River and Steens basalts. We propose a model in which (1) Miocene flood basalts and widespread silicic rocks are the result of emplacement of a plume head near the craton margin, enhanced by flow up a topographic gradient along the base of the lithosphere at the craton margin; (2) the HLP trend is the result of westward flow originating at the craton margin; and (3) the YSRP trend is the trace of the motion of the North American plate over the tail of the plume.
Experimental study of gas‐fluidized granular flows with implications for pyroclastic flow emplacement
Authors: Roche O. , Gilbertson M. A. , Phillips J. C. , Sparks R. S. J.
Published: October 2004

Experiments have been carried out on initially gas‐aerated and gas‐fluidized granular flows propagating into a horizontal channel. After lateral acceleration following release of the originally fluidized bed, two contrasting flow behaviors were observed, which reflected the degree of initial fluidization and the grain size. Initial fluidization disrupts the interparticle contact network, which controls internal friction of the static bed. The flow regime then depends on the timescale needed to reestablish a strong contact network, and this time increases as the grain size decreases. Initially aerated and fluidized flows of coarse particles (>≈100 μm) and initially aerated flows of fine particles (<≈100 μm) behave as their nonfluidized counterparts and they propagate as a wedge, with decelerating velocities so that the front position increases as the ∼0.8 power of time. In contrast, initially fluidized flows of fine particles propagate for most of their duration at constant thickness and frontal velocity in a similar fashion to the slumping regime of buoyancy‐driven gravity currents of Newtonian fluids. We have determined a Froude number Fr for such flows of ≈2.6 consistent with published data from experimental and theoretical investigations on inviscid fluids. This implies that internal particle friction can be neglected in describing the dynamics of initially fluidized, concentrated fine granular flows. However, all flows are characterized by a short, final stopping phase whose timescale gives an estimate of the kinetics required to reestablish a strong contact network and form a static deposit. These results suggest that fines‐rich pyroclastic flows may propagate as inviscid fluids for most of their emplacement.
The Sumatra subduction zone: A case for a locked fault zone extending into the mantle
Authors: Simoes Martine , Avouac Jean Philippe , Cattin Rodolphe , Henry Pierre
Published: October 2004

A current view is that the portion of the subduction interface that remains locked in the time interval between large interplate earthquakes, hereinafter referred to as the locked fault zone (LFZ), does not extend into the mantle because serpentinization of the mantle wedge would favor stable aseismic sliding. Here, we test this view in the case of the Sumatra subduction zone where the downdip end of the LFZ can be well constrained from the pattern and rate of uplift deduced from coral growth and from GPS measurements of horizontal deformation. These geodetic data are modeled from a creeping dislocation embedded in an elastic half‐space and indicate that the LFZ extends 132 ± 10/7 km from the trench, to a depth between 35 and 57 km. By combining this information with the geometry of the plate interface as constrained from two‐dimensional gravimetric modeling and seismicity, we show that the LFZ extends below the forearc Moho, which is estimated to lie at a depth of ∼30 km, at a horizontal distance of 110 km from the trench. So, in this particular island arc setting, the LFZ most probably extends into the mantle, implying that either the mantle is not serpentinized, or that the presence of serpentine does not necessarily imply stable sliding. From thermal modeling, the temperature at the downdip end of the LFZ is estimated to be 260 ± 100°C. This temperature seems too low for thermally activated ductile flow, so that aseismic slip is most probably due to pressure and/or temperature induced steady state brittle sliding, possibly favored by fluids released from the subducting slab.
Environmental snapshots from ACE‐Asia
Authors: Kahn Ralph , Anderson Jim , Anderson Theodore L. , Bates Tim , Brechtel Fred , Carrico Christian M. , Clarke Antony , Doherty Sarah J. , Dutton Ellsworth , Flagan Richard , Frouin Robert , Fukushima Hajime , Holben Brent , Howell Steve , Huebert Barry , Jefferson Anne , Jonsson Haflidi , Kalashnikova Olga , Kim Jiyoung , Kim Sang‐Woo , Kus Pinar , Li Wen‐Hao , Livingston John M. , McNaughton Cameron , Merrill John , Mukai Sonoyo , Murayama Toshiyuki , Nakajima Teruyuki , Quinn Patricia , Redemann Jens , Rood Mark , Russell Phil , Sano Itaru , Schmid Beat , Seinfeld John , Sugimoto Nobuo , Wang Jian , Welton Ellsworth J. , Won Jae‐Gwang , Yoon Soon‐Chang
Published: October 2004

On five occasions spanning the Asian Pacific Regional Aerosol Characterization Experiment (ACE‐Asia) field campaign in spring 2001, the Multiangle Imaging Spectroradiometer spaceborne instrument took data coincident with high‐quality observations by instruments on two or more surface and airborne platforms. The cases capture a range of clean, polluted, and dusty aerosol conditions. With a three‐stage optical modeling process, we synthesize the data from over 40 field instruments into layer‐by‐layer environmental snapshots that summarize what we know about the atmospheric and surface states at key locations during each event. We compare related measurements and discuss the implications of apparent discrepancies, at a level of detail appropriate for satellite retrieval algorithm and aerosol transport model validation. Aerosols within a few kilometers of the surface were composed primarily of pollution and Asian dust mixtures, as expected. Medium‐ and coarse‐mode particle size distributions varied little among the events studied; however, column aerosol optical depth changed by more than a factor of 4, and the near‐surface proportion of dust ranged between 25% and 50%. The amount of absorbing material in the submicron fraction was highest when near‐surface winds crossed Beijing and the Korean Peninsula and was considerably lower for all other cases. Having simultaneous single‐scattering albedo measurements at more than one wavelength would significantly reduce the remaining optical model uncertainties. The consistency of component particle microphysical properties among the five events, even in this relatively complex aerosol environment, suggests that global, satellite‐derived maps of aerosol optical depth and aerosol mixture (air‐mass‐type) extent, combined with targeted in situ component microphysical property measurements, can provide a detailed global picture of aerosol behavior.
Formal solution to the electromagnetic scattering by buried dielectric and metallic spheres
Authors: Wang Gong Li , Chew Weng Cho
Published: October 2004

The canonical problem of electromagnetic scattering by a buried dielectric or metallic sphere is studied in this paper. Two expansions are presented, of which one is the expansion of the vector plane waves into the vector spherical waves. The other is its converse, the expansion of the vector spherical waves into the vector plane waves. The use of two expansions is to facilitate matching the boundary conditions at the planar ground surface and the sphere surface. A general full‐wave analytic solution is given in which not only the high‐order multipoles but also the multiple reflections between the sphere and the ground surface are considered. Oblique plane wave and vertical magnetic dipole are considered as sources, though the illumination can be of arbitrary form with the use of Weyl identity.
Bremsstrahlung effects in energetic particle detectors
Authors: Tuszewski M. , Cayton T. E. , Ingraham J. C. , Kippen R. M.
Published: October 2004

The energetic charged particles of the Earth's magnetosphere are routinely detected by solid‐state satellite instruments. Quantitative data are increasingly required for engineering dose calculations and for space weather science. However, the design of some energetic particle detectors can be severely constrained. Background effects must be accurately modeled in such cases to extract quantitative information. In particular, bremsstrahlung radiation from electrons impacting the detector and the satellite often dominates the background noise. Numerical tools are presented here to calculate total bremsstrahlung effects in energetic electron detectors. The calculations are illustrated for the low‐energy particle detector of current Global Positioning System satellites.
Neotectonics in the foothills of the southernmost central Andes (37°–38°S): Evidence of strike‐slip displacement along the Antiñir‐Copahue fault zone
Authors: Folguera Andrés , Ramos Víctor A. , Hermanns Reginald L. , Naranjo José
Published: October 2004

The Antiñir‐Copahue fault zone (ACFZ) is the eastern orogenic front of the Andes between 38° and 37°S. It is formed by an east vergent fan of high‐angle dextral transpressive and transtensive faults, which invert a Paleogene intra‐arc rift system in an out of sequence order with respect to the Cretaceous to Miocene fold and thrust belt. 3.1–1.7 Ma volcanic rocks are folded and fractured through this belt, and recent indicators of fault activity in unconsolidated deposits suggest an ongoing deformation. In spite of the absence of substantial shallow seismicity associated with the orogenic front, neotectonic studies show the existence of active faults in the present mountain front. The low shallow seismicity could be linked to the high volumes of retroarc‐derived volcanic rocks erupted through this fault system during Pliocene and Quaternary times. This thermally weakened basement accommodates the strain of the Antiñir‐Copahue fault zone, absorbing the present convergence between the South America and Nazca plates.
Predicting wetland water storage
Authors: Krasnostein A. L. , Oldham C. E.
Published: October 2004

A conceptual wetland model was developed to describe the interactions between a wetland, the surrounding catchment, and the local groundwater. Numerical evaluation of the wetland water balance was achieved by applying a bucket model. The model required little calibration and used physically based catchment properties and recorded climatic data sets. Model flexibility lends itself to application across a broad range of wetland types from seasonally to permanently inundated (or saturated) systems. The model was applied to Loch McNess, a permanent open water body of maximum depth 3.4 m located on the Swan Coastal Plain in Perth, Western Australia. Groundwater flow was found to dominate the wetland water balance. The local groundwater was shown to be interactive, responding to specific conditions within the wetland. The model enabled differentiation between groundwater components. Flow paths were separated into groundwater inflows and outflows, and an overflow mechanism connecting the wetland to the nearby cave system was identified. Results from this study show that the bucket model can be used to isolate dominant hydrological processes of a wetland system, focus field studies of wetland hydrology, or facilitate management of the system.
Radiometric sensitivity to soil moisture at 1.4 GHz through a corn crop at maximum biomass
Authors: Hornbuckle B. K. , England A. W.
Published: October 2004

Radiometric sensitivity to soil moisture at 1.4 GHz through a corn canopy at a maximum biomass of 8.0 kg m−2 (water column density of 6.3 kg m−2) was much higher than expected. The magnitude of the measured sensitivity of horizontally polarized brightness temperature to the 0–3 cm volumetric soil water content was at least 1.5 K per 0.01 m3 m−3 and could have been as high as 2.5 K per 0.01 m3 m−3. Vertically polarized brightness temperature was 0.5 K per 0.01 m3 m−3 less sensitive than horizontally polarized brightness temperature. A widely used radiative transfer model that assumes a uniform distribution of vegetation in the canopy underestimated this soil moisture sensitivity at horizontal polarization by over 1 K per 0.01 m3 m−3. Given an appropriate emission model that correctly accounts for the differences in transparency between heterogeneous canopies (as compared to the wavelength) such as corn and relatively homogeneous canopies such as grass, it appears that there will be practical sensitivity to soil moisture through corn (and most, if not all, row crops) throughout the growing season.
How soil moisture, rain pulses, and growth alter the response of ecosystem respiration to temperature
Authors: Xu Liukang , Baldocchi Dennis D. , Tang Jianwu
Published: October 2004

In this paper, we analyzed 3 years of carbon flux data from continuous eddy covariance measurements to investigate how soil moisture, rain pulses, and growth alter the response of ecosystem respiration to temperature. The data were acquired over an annual grassland and from the grass understory of an oak/grass savanna ecosystem in California. We observed that ecosystem respiration was an exponential function of soil temperature during the winter wet season and a jump in ecosystem respiration occurred, at comparable temperatures, during the spring growth period. The depletion of the moisture from the soil reservoir, during spring, limited ecosystem respiration after its volumetric water content dropped below a threshold of 0.15 m3 m−3. The senescence of grass during the summer switched the source of ecosystem respiration to heterotrophic bacteria and fungi. During the summer, respiration proceeded at a low basal rate (about 0.10 to 0.3 g C m−2 d−1), except when summer rain events stimulated large dynamic pulses in heterotrophic respiration. Peak respiratory pulses were on the order of 60–80 times baseline and could not be explained by functions that depend on mean soil moisture and temperature. We found that the magnitude of the respiratory pulses was inversely related to its prerain value and that the time constant, describing the exponential decay of the respiratory pulses after the rain event, was a function of the amount of rainfall. The amount of carbon lost, in association with a few summer rain events, was greater at the site with higher primary productivity and soil carbon content.
Measurements of isotope and elemental ratios of air from polar ice with a new on‐line extraction method
Authors: Huber Christof , Leuenberger Markus
Published: October 2004

A recently developed continuous on‐line extraction and analyzing technique for air trapped in ice cores has been improved and tested. The technique allows fast high‐resolution measurements of the isotopic and elemental ratios of the main air components nitrogen, oxygen, and argon. Continuous measurements of up to 1 m long ice sections can be performed with a resolution of ∼3 cm (running average). For nitrogen and oxygen isotope ratios the accuracy and reproducibility are comparable to conventional melt extraction techniques. It depends on the desired resolution and the composition of the ice. For either pure bubble or complete bubble free ice the reproducibility and accuracy for a resolution of 3 cm are ±<0.02‰ for δ15N, ±<0.05‰ for δ18O, and ±<0.06‰ for δ17O. Furthermore, δAr/O2 (±1‰), δO2/N2, δAr/N2 (both ±5–8‰), and δ36Ar (±0.2–0.3‰) can be determined as well. The precision of elemental ratios is good enough to resolve variations that are detected in ice at depths where air bubbles form clathrate hydrates. Surprisingly, at these depths the elemental ratios show roughly annual variations probably due to strong fractionations between air in clathrate hydrates and air in bubbles. On the basis of our measuring precision we cannot exclude similar effects for isotope ratios.
Inorganic iodine speciation in tropical Atlantic aerosol
Authors: Baker A. R.
Published: October 2004

The inorganic speciation of soluble iodine has been determined in size‐fractionated aerosol samples collected from the tropical Atlantic Ocean in October/November 2002 during Meteor cruise 55, a pilot study of the German SOLAS programme. Iodide concentrations were appreciable (>0.4 pmol m−3) in the fine and coarse modes of all samples whereas iodate was occasionally below detection limit (∼0.7 pmol m−3) in samples from northern hemisphere air and was undetectable in all samples from the southern hemisphere. Iodine was enriched, and chlorine and bromine depleted, relative to seasalt concentrations. The majority of Cl− loss was due to the seasalt displacement reaction. Halogen activation (I− + HOX + H+ = IX + H2O) may also have occurred, but did not result in net I− depletion in any aerosol fraction. The observed variations of iodine speciation cannot be reproduced by current models of aerosol iodine chemistry.
Furrow flexure and ancient heat flux on Ganymede
Authors: Nimmo F. , Pappalardo R. T.
Published: October 2004

Stereo‐derived topographic profiles across furrows in the ancient (∼4 Gyr) dark terrain of Galileo Regio, Ganymede, suggest flexural uplift. Modeling of the rift‐flank profiles implies an effective elastic thickness of ≈0.5 km, heat fluxes in the range 60–80 mW m−2 at the time of deformation, and a brittle‐ductile transition depth of 2–3 km. The elastic thicknesses are comparable to estimates for grooved terrain on Ganymede, and chaos regions on Europa, and may be characteristic of the point during cooling at which the available stresses can no longer cause significant ice shell deformation. The furrowed dark terrain heat fluxes exceed likely chondritic values, and are plausibly a result of early cooling of Ganymede following accretion. Non‐synchronous rotation may have contributed to the 2–3 MPa stresses required to cause the observed deformation.
Spectroscopic evidence for hydrous iron sulfate in the Martian soil
Authors: Lane Melissa D. , Dyar M. Darby , Bishop Janice L.
Published: October 2004

Despite in situ analyses by several landers, the composition of the Martian soil remains unclear. Recently, constituent minerals in the soil have been proposed from thermal emissivity and Mössbauer spectroscopic data from Mars. These data were interpreted to show spectral evidence for carbonate and an unspecified mineral containing bound water, as well as olivine. Here we present an alternative interpretation, suggesting that these spectral features can be satisfied by a single type of mineral, namely hydrous iron sulfates. Acidic waters necessary for production of hydrous iron sulfates would preclude carbonate formation and indicate a dramatically different chemical environment on Mars, in which olivine would be highly unstable and unlikely to survive soil formation, regardless of its presence in the rocks. Hydrous iron sulfates are efflorescent salts and may be crusting agents in the Martian soils.
Viscoelastic earthquake cycle models with deep stress‐driven creep along the San Andreas fault system
Authors: Johnson K. M. , Segall P.
Published: October 2004

We develop a two‐dimensional boundary element earthquake cycle model including deep interseismic creep on vertical strike‐slip faults in an elastic lithosphere coupled to a viscoelastic asthenosphere. Uniform slip on the upper part of the fault is prescribed periodically to represent great strike‐slip earthquakes. Below the coseismic rupture the fault creeps in response to lithospheric shear stresses within a narrow linear viscous fault zone. The model is applied to the GPS contemporary velocity field across the Carrizo Plain and northern San Francisco Bay segments of the San Andreas fault, as well as triangulation measurements of postseismic strain following the 1906 San Francisco earthquake. Previous analysis of these data, using conventional viscoelastic coupling models without stress‐driven creep [Segall, 2002], shows that it is necessary to invoke different lithosphere‐asthenosphere rheology in northern and southern California in order to explain the data. We show that with deep stress‐driven interseismic creep on the San Andreas fault, the data can be explained with the same rheology for northern and southern California. We estimate elastic thickness in the range 44–100 km (95% confidence level), fault zone viscosity per unit width of 0.5–8.2 × 1017Pa s/m, and asthenosphere relaxation time of 24–622 years (0.1–2.9 × 1020Pa s) for northern and southern California. We estimate a slip rate of 21–27 mm/yr and recurrence time of 188–315 years for the northern San Francisco Bay San Andreas fault and slip rate of 32–42 mm/yr with recurrence time of 247–536 years for the Carrizo Plain.
Seasonal accumulation timing and preservation of nitrate in firn at Summit, Greenland
Authors: Burkhart John F. , Hutterli Manuel , Bales Roger C. , McConnell Joseph R.
Published: October 2004

In a yearlong investigation of the air‐snow transfer function for nitrate (NO3−) at the Greenland Environmental Observatory, Summit (3203 m above sea level), surface snow concentrations measured every other day were compared with levels measured in 10 snow pits dug adjacent to accumulation stakes. Concentrations in the surface snow ranged from 0.4 to 34 μM with a mean of 2.9 ± 1.9 μM. Measured firn profiles in the snow pits had a maximum NO3− concentration of 12 μM and a mean of 2.7 ± 0.5 μM. Reconstructed profiles from surface snow observations and accumulation data closely matched the observed profiles. The small difference in preserved concentrations from observed surface snow concentrations gives evidence of only 7% postdepositional loss at this site (mean annual accumulation ∼23 g cm−2 yr−1). Removing the three highest outliers (which may originate from local sources) of surface snow concentration drops the mean to 2.7 μM, further demonstrating preservation. Results indicate that at this site accumulation is the most significant process affecting preservation of nitrate in the firn. Other rapid postdepositional processes may impact surface snow concentrations, but do not appear to significantly change the preserved record. The inverse analysis of converting preserved records to surface snow concentrations provides equivalent evidence of the same preservation.
Validation of nonlinear inverse algorithms with Markov chain Monte Carlo method
Authors: Tamminen J.
Published: October 2004

The data processing of remote sensing measurements usually involves solving a nonlinear inverse problem. The error characterization is typically done by assuming linearity around the estimated likelihood point, and a covariance matrix approximating a Gaussian uncertainty is given. However, often the solutions are not Gaussian. We describe here a methodology for validating the traditional error characterization by applying the Markov chain Monte Carlo (MCMC) technique. The validation methodology is applied to the inverse problems of the Global Ozone Monitoring by Occultation of Stars (GOMOS) stellar occultation instrument. The adaptive Metropolis algorithm that is used makes the implementation of the MCMC technique effortless. We demonstrate the approach by using real GOMOS data from two occultations, using a bright and a dim star. It is shown that the covariance matrices that are computed in the operational GOMOS data processing characterize well the error structure of the GOMOS measurements if we assume that noise is Gaussian and no prior information is used. However, we also observe that a significant improvement in retrieved parameters is achieved if a positivity prior is introduced. Such prior information can be correctly modeled with the MCMC technique. The sensitivity of the retrieval on the noise characterization is studied by comparing the results obtained with the operational algorithm with a more robust inversion based on ℓ1norm. At low altitudes a more robust inversion improves the results. In addition, we demonstrate how the MCMC technique can be used to study the modeling errors in the case of nonlinear problems.
Late Holocene variability in Florida Current surface density: Patterns and possible causes
Authors: Lund D. C. , Curry W. B.
Published: October 2004

Planktonic foraminiferal δ18O time series from three well‐dated, high sedimentation rate cores near the Florida Keys (24.4°N, 83.3°W) exhibit repeated centennial to millennial‐scale oscillations during the late Holocene. Isotopic shifts of 0.2–0.3‰ over the past 5200 years represent changes in sea‐surface temperature (SST) of 1.0–1.5°C or salinity variability of 1–2 psu. The largest significant isotopic events are centered at approximately 200, 2000, 3200, and prior to 4000 calendar years BP. High Florida Current δ18O during the Little Ice Age (LIA) correlates with published records of high δ18O in the Sargasso Sea and low SST off the coast of west Africa. An interval of generally low δ18O in the Florida Straits from 1800 to 500 years BP is synchronous with the Medieval Warm Period off west Africa but leads low δ18O in the Sargasso Sea by several hundred years. Synchronous cooling across the subtropical gyre during the LIA is difficult to explain using interannual North Atlantic Oscillation patterns but may be consistent with the simulated effects of reduced solar irradiance. At frequencies between 1/1000 and 1/300 years during the Late Holocene, Florida Current δ18O is coherent with a published estimate of 14C production rate. Radiocarbon production seems to lead δ18O at these frequencies, but uncertainty in the phase calculation precludes a clear lead‐lag relationship. At frequencies lower than 1/300 years, Florida Current δ18O is coherent and in phase with atmospheric Δ14C. The coherence of Δ14C and δ18O at periods >1000 years implies oceanic circulation may play a role in modulating atmospheric radiocarbon on millennial timescales.
El Niño–Southern Oscillation–related salinity variations recorded in the skeletal geochemistry of a Porites coral from Espiritu Santo, Vanuatu
Authors: Kilbourne K. Halimeda , Quinn Terrence M. , Taylor Frederick W. , Delcroix Thierry , Gouriou Yves
Published: October 2004

Coral skeletal geochemistry offers the potential to reconstruct the sea surface salinity (SSS) history of the tropical oceans on seasonal to interannual and perhaps centennial timescales because of the strong link between variation in SSS and seawater δ18O in tropical regions. We explore this potential using a monthly resolved, 65‐year record of skeletal δ18O and Sr/Ca variations in a Porites coral from Espiritu Santo, Vanuatu. We demonstrate that El Niño–Southern Oscillation–related climate variability strongly influences coral δ18O at Santo through local salinity changes associated with the position of the South Pacific Convergence Zone and the movement of its associated salinity front. Such a demonstration provides the “ground truth” data that can be used to place paleoclimate variability estimated using existing fossil coral records from this region into a modern conceptual framework. We also evaluate different methods of combining coral δ18O and Sr/Ca to reconstruct SSS and conclude that the coral δ18O anomaly time series provides the best fit to recent in situ SSS data at Santo.
Agricultural pollution control under Spanish and European environmental policies
Authors: Martínez Yolanda , Albiac José
Published: October 2004

Nonpoint pollution from agriculture is an important environmental policy issue in Spain and the European Union. Agricultural pollution in Spain is being addressed by the National Irrigation Plan and by the European Water Framework Directive. This article contributes to the ongoing policy decision process by analyzing nonpoint pollution control and presenting results on the efficiency of abatement measures. Results question the reliance of the Water Framework Directive on water pricing as a pollution instrument for reaching good status for all waters because higher water prices close to full recovery cost advocated by the directive appear to be inefficient as an emission control instrument. Another important result is that abatement measures based on input taxes and standards on nitrogen appear to be more suitable than the National Irrigation Plan subsidies designed to promote irrigation investments. The results also contribute with further evidence to the discussion on the appropriate instrument base for pollution control, proving that nonpoint pollution control instruments cannot be assessed accurately without a correct understanding of the key underlying biophysical processes. Nonpoint pollution is characterized by nonlinearities, dynamics, and spatial dependency, and neglect of the dynamic aspects may lead to serious consequences for the design of measures. Finally, a quantitative assessment has been performed to explore discriminating measures based on crop pollution potential on vulnerable soils. No significant welfare gains are found from discriminating control, although results are contingent upon the level of damage, and discrimination could be justified in areas with valuable ecosystems and severe pollution damages.
Nitric oxide‐dependent β2‐adrenergic dilatation of rat aorta is mediated through activation of both protein kinase A and Akt
Authors: Ferro Albert , Coash Marcy , Yamamoto Takahiro , Rob Jubli , Ji Yong , Queen Lindsay
Published: October 2004

Vasorelaxation to β2‐adrenoceptor stimulation occurs through both endothelium‐dependent and endothelium‐independent mechanisms, and the former is mediated through Ca2+‐independent activation of endothelial‐type nitric oxide synthase (NOS‐3). Since Ca2+‐independent NOS‐3 activation may occur through its serine phosphorylation via protein kinase A (PKA) or Akt, we determined the PKA and Akt dependency of β2‐adrenergic relaxation of rat aorta.

Rat aortic rings were pre‐incubated with the PKA inhibitor H‐89 (10−7 M), the phosphatidylinositol 3‐kinase (PI3K) inhibitor wortmannin (5 × 10−7 M), Akt inhibitor (10−5 M), or vehicle, in the absence or presence of the NOS inhibitor NG‐nitro‐L‐arginine methyl ester (L‐NAME, 10−4 M). Rings were then contracted with phenylephrine (10−7 M), and concentration–relaxation responses determined to the β2‐adrenoceptor agonist albuterol.

Rings exhibited a concentration‐dependent relaxation to albuterol: pEC50 6.9±0.2, Emax 88.2±4.0%. L‐NAME attenuated Emax to 60.2±3.5% (P<0.001).

In the presence of L‐NAME, wortmannin or Akt inhibitor did not influence albuterol responses, whereas H‐89 reduced Emax further, to 27.5±2.2% (P<0.001).

In the absence of L‐NAME, Emax to albuterol was reduced by H‐89, wortmannin or Akt inhibitor, to 56.2±2.2, 56.0±1.6 and 55.4±1.8%, respectively (P<0.001 for each); the combinations H‐89 plus wortmannin or H‐89 plus Akt inhibitor reduced Emax further still.

Western blotting of NOS‐3 immunoprecipitates from rat aortas confirmed that albuterol increased serine phosphorylation of NOS‐3, and this increase was attenuated by H‐89 or Akt inhibitor.

Our results indicate that β2‐adrenoceptor stimulation relaxes rat aorta through both NO‐dependent and independent mechanisms. The latter is predominantly PKA‐mediated, whereas the former occurs through both PKA and PI3K/Akt activation.

British Journal of Pharmacology (2004) 143, 397–403. doi:10.1038/sj.bjp.0705933