bluuebunny/crossref_metadata_2025 huggingface dataset:
Tradeoffs associated with sediment‐maintenance flushing flows: a simulation approach to exploring non‐inferior options
Authors: Wu Fu‐Chun , Chou Yi‐Ju
Published: July 2004

Sediment‐maintenance flushing flows designed to mimic the action of natural floods in removing the accumulated fine sediments from the channel and loosening the gravel bed have been increasingly proposed as an effective alternative in dam management and a required component of riverine restoration programmes. However, reservoir releases are generally associated with financial and environmental costs, thus it is highly desirable to specify flushing flows as accurately as possible. In this paper we present a simulation approach to evaluating flushing flows and exploring the tradeoffs associated with non‐inferior flushing options. A two‐fraction sediment routing model is used to simulate the gravel‐sand bed response to flushing flows. The results reveal that the sand cleansing effect propagates from upstream to downstream and from surface to subsurface. Under a steady gravel supply from upstream, an equilibrium state of gravel transport and bed degradation is eventually reached in the simulation reach. The flushing flow and sediment transport system investigated in this study involves a transient state variable (bed sand content), a decision variable (flushing flow discharge), a flushing goal (ultimate bed sand content), and three outcomes to be minimized (flushing duration, released water volume, and total gravel loss). A series of numerical simulations are carried out with a range of flows and pre‐flushing bed sediment conditions. The results reveal that the flushing efficiency is higher for the larger flow. However, for flows greater than ∼100 m3/s the flushing duration is less sensitive to the flow discharge, thus the system may be simplified as a bi‐objective one. The gravel loss and water volume are two conflicting outcomes within the non‐inferior flow region. Under a worse bed sediment condition, the feasible flushing options are constrained in a narrower range and also associated with higher costs. The tradeoffs between the conflicting outcomes are quantitatively displayed with the transformed feasible solutions in the objective space. We provide here a general and practical approach permitting a quantitative evaluation of the different flushing options that is appropriate to the level of data typically available. Copyright © 2004 John Wiley & Sons, Ltd.
Refinement of the wetted perimeter breakpoint method for setting cease‐to‐pump limits or minimum environmental flows
Authors: Reinfelds Ivars , Haeusler Tim , Brooks Andrew J. , Williams Simon
Published: July 2004

Analysis of inflections or breakpoints apparent in relationships between measures of wetted perimeter and discharge can be used to assist in the determination of minimum environmental flows for perennial rivers. This paper suggests refinements and provides an example application of the wetted perimeter method for the determination of cease‐to‐pump limits in a perennial, unregulated gravel‐bed river subject to increasing levels of surface water extraction. HEC‐GeoRAS modelling outputs of riffle wetted area are used to illustrate that the magnitude of the discharge selected to represent 100% habitat availability is of crucial importance to the breakpoint method. Because of the dependence of the technique on this assumption, we suggest that it is prudent to use an upper and lower limiting discharge based on an assessment of the degree of flow variability to develop a flow range around the zone of diminishing return in the wetted perimeter to discharge relationship. For rivers exhibiting a low degree of flow variability, the mean and median daily flows are likely to provide appropriate discharges for representation of 100% habitat availability. For perennial rivers with a higher degree of flow variability and considerable differences between the mean and median daily flows we suggest use of the 50th and 80th flow duration percentiles. Wetted perimeter breakpoint results are also influenced by the degree to which areas of non‐riffle habitat are included in the analysis. Inclusion of excessive pool areas can lead to significant reductions in resultant recommendations for cease‐to‐pump limits or minimum environmental flows. Integration of hydraulic model outputs with GIS for wetted perimeter analysis of riffles provides a useful, rapid, field‐based approach that can assist with determination of cease‐to‐pump limits or minimum environmental flows in gravel‐bed rivers. However, care is needed in its application and interpretation as the technique is prone to numerous subjective choices that have a substantial influence on results. Copyright © 2004 John Wiley & Sons, Ltd.
A general momentum theory applied to an energy‐extracting actuator disc
Authors: Sharpe D. J.
Published: July 2004

A general momentum theory for an energy‐extracting actuator disc modelling a rotor with a multiplicity of blades having radially uniform circulation is presented that includes the effects of wake rotation and expansion. A parallel theory directed at the propeller has been published elsewhere, but not one intended for the wind turbine. The rotation of the wake is shown to be accompanied by a fall in static pressure that is additional to that which occurs across the actuator disc and accounts for the energy extraction from the wind. Energy extraction is recognized in the fully developed wake by the flow regaining the static pressure of the undisturbed wind at the expense of the kinetic energy in the wake. Because the wake is still rotating in the fully developed wake, the additional fall in static pressure appears there also and so does not augment the energy extraction. However, the additional fall in pressure would cause a discontinuity in pressure across the fully developed wake but is prevented by a further slowing down of the wake. The additional slowing down extracts a little more energy from the flow than that predicted by the simple momentum theory, which does not include wake rotation. The overall effect of wake rotation on energy extraction is very small for wind turbines operating at high tip speed ratios but can significantly increase the predicted power output for turbines operating at low tip speed ratios. Copyright © 2004 John Wiley & Sons, Ltd.
Aeroelastic stability predictions for a MW‐sized blade
Authors: Lobitz Don W.
Published: July 2004

Classical aeroelastic flutter instability historically has not been a driving issue in wind turbine design. In fact, rarely has this issue even been addressed in the past. Commensurately, among the wind turbines that have been built, rarely has classical flutter ever been observed. However, with the advent of larger turbines fitted with relatively softer blades, classical flutter may become a more important design consideration. In addition, innovative blade designs involving the use of aeroelastic tailoring, wherein the blade twists as it bends under the action of aerodynamic loads to shed load resulting from wind turbulence, may increase the blade's proclivity for flutter. With these considerations in mind it is prudent to revisit aeroelastic stability issues for a MW‐sized blade with and without aeroelastic tailoring. Focusing on aeroelastic stability associated with the shed wake from an individual blade turning in still air, the frequency domain technique developed by Theodorsen for predicting classical flutter in fixed wing aircraft has been adapted for use with a rotor blade. Results indicate that the predicted flutter speed of a MW‐sized blade is slightly greater than twice the operational speed of the rotor. When a moderate amount of aeroelastic tailoring is added to the blade, a modest decrease (12%) in the flutter speed is predicted. By comparison, for a smaller rotor with relatively stiff blades the predicted flutter speed is approximately six times the operating speed. When frequently used approximations to Theodorsen's method are implemented, drastic underpredictions result, which, while conservative, may adversely impact blade design. These underpredictions are also evident when this MW‐sized blade is analysed using time domain methods. Published in 2004 by John Wiley & Sons, Ltd.
Novel high‐resolution silicon drift detectors
Authors: Lechner P. , Pahlke A. , Soltau H.
Published: July 2004

Silicon drift detectors (SDDs) are used as energy‐dispersive detectors for x‐ray fluorescence analysis in commercial systems. Because of the low capacitance of the readout anode, achieved by the device topology and by the integration of the first FET on the chip, noise contributions are very small, allowing good energy resolution at low shaping times and high count rates. Typical energy resolution is better than 147 eV FWHM at 5.9 keV (Mn Kα), at −10°C. This allows the chips to be cooled with a thermoelectric element, avoiding the use of liquid nitrogen. SDD chips are produced at MPI‐Halbleiterlabor in Munich with different geometries and areas. Recently, a new SDD has been developed which places the anode and the integrated JFET at the margin of the chip where it can easily be shielded from direct irradiation with the use of a collimator. The new layout allows the design of a readout anode with smaller area and therefore reduces the capacitance to values of about 120 fF compared with 200–250 fF with standard SDDs. The result is an improvement in energy resolution down to 128 eV at −15°C. A second effect is the enhancement of the peak‐to‐background values to 6000 homogeneously across the active area of the detector. Copyright © 2004 John Wiley & Sons, Ltd.
Extending the quantitative analytical capabilities of the EDXRF technique for plant‐based samples
Authors: Bamford S. A. , Jaksic M. , Medunic Z. , Wegrzynek D. , Chinea‐Cano E. , Markowicz A.
Published: July 2004

The energy‐dispersive x‐ray fluorescence (EDXRF) technique has limitations in the quantitative analysis of light elements (low‐Z analytes with Z < 10), for many reasons. This work, however, circumvents the problem through an a priori determination of low‐Z analytes, representative of plant‐based samples. The main purpose of this work was to characterize the major elements in the dark matrix of some plant‐based samples (including biomonitors) using Rutherford backscattering spectrometry (RBS), and the results provided as a generalized input for EDXRF analysis. The derived stoichiometry and mass ratio for the moss, lichen, and cotton cellulose samples analyzed were found to be similar and close to C7H10O5, with an average matrix of C = 49.8%, H = 4.0% and O = 45.8%. Quantitative analysis of plant‐based reference material IAEA‐336 (lichen) was subsequently carried out. Use of the a priori determined dark matrix elements (from one‐time RBS spectrometry) extended the scope of applicability of the EDXRF quantitative methods used, and improved accuracy in the elemental analysis of plant‐based samples. The results obtained were in good agreement with the reference values. Copyright © 2004 John Wiley & Sons, Ltd.
Characterization of x‐rays emerging from between reflector and sample carrier in reflector‐assisted TXRF analysis
Authors: Tsuji Kouichi , Delalieux Filip
Published: July 2004

The possible application of an Si reflector, which is placed just above the sample carrier in total reflection x‐ray fluorescence (TXRF) analysis, was investigated. The x‐rays that were emitted from an Mo tube and passed between the Si reflector and the Si sample carrier were analyzed with an Si drift detector. In our experimental setup, the angle between the reflector and the sample carrier can be changed by adjusting the inclination of the reflector. The intensity of the x‐rays that emerged from between the two Si surfaces drastically changed depending on the reflector angle. At a proper reflector angle, this intensity showed a maximum and, in addition, the Compton peak in the x‐ray spectrum was suppressed. When this x‐ray beam was used for excitation of TXRF signals, the highest intensity of x‐ray fluorescence emitted from the sample was detected, indicating that these experimental conditions are useful for the enhancement of TXRF intensities. Copyright © 2004 John Wiley & Sons, Ltd.
XRF analysis of arsenic‐doped skin phantoms
Authors: Studinski R. C. N. , McNeill F. E. , Chettle D. R. , O'Meara J. M.
Published: July 2004

Chronic arsenic poisoning can lead to serious health problems including vascular disorders and cancer. Therefore, the development of a system to measure arsenicin vivowould be useful in monitoring exposure. In particular, as skin is one of the tissues in which arsenic has health consequences and is stored for a prolonged period of time, anin vivomeasure of skin arsenic content would be a clinically useful measure of chronic exposure. The preliminary development of an x‐ray fluorescence system to measure arsenicin vivois reported. Standard addition arsenic‐ doped polyester resin phantoms were prepared, and the fluorescence induced by silver K x‐rays from a109Cd source was measured. Preliminary estimates of detection limits for an 8 mm thick phantom and an effective dose of ∼0.3 µSv are 3.5 ± 0.2 and 10.3 ± 0.5 ppm in 90 and 180° measurement geometries, respectively, for a measurement time of 30 min. Copyright © 2004 John Wiley & Sons, Ltd.
The gun4 gene is essential for cyanobacterial porphyrin metabolism
Authors: Wilde Annegret , Mikolajczyk Sandra , Alawady Ali , Lokstein Heiko , Grimm Bernhard
Published: July 2004

Ycf53 is a hypothetical chloroplast open reading frame with similarity to the Arabidopsis nuclear gene GUN4. In plants, GUN4 is involved in tetrapyrrole biosynthesis. We demonstrate that one of the two Synechocystis sp. PCC 6803 ycf53 genes with similarity to GUN4 functions in chlorophyll (Chl) biosynthesis as well: cyanobacterial gun4 mutant cells exhibit lower Chl contents, accumulate protoporphyrin IX and show less activity not only of Mg chelatase but also of Fe chelatase. The possible role of Gun4 for the Mg as well as Fe porphyrin biosynthesis branches in Synechocystis sp. PCC 6803 is discussed.
Hexose‐6‐phosphate dehydrogenase determines the reaction direction of 11β‐hydroxysteroid dehydrogenase type 1 as an oxoreductase
Authors: Atanasov Atanas G , Nashev Lyubomir G , Schweizer Roberto A.S , Frick Christoph , Odermatt Alex
Published: July 2004

The impact of hexose‐6‐phosphate dehydrogenase (H6PDH) on 11β‐hydroxysteroid dehydrogenase (11β‐HSD) type 1 activity was investigated upon coexpression in HEK‐293 cells. Confocal microscopy analysis indicated colocalisation of both enzymes at the lumenal side of the endoplasmic reticulum (ER) membrane. Functional analysis in intact cells revealed fivefold stimulation of 11β‐HSD1 oxoreductase activity and sixfold decrease of dehydrogenase activity upon coexpression with H6PDH, without changing kinetic parameters in cell lysates. Thus, H6PDH directly determines the reaction direction of 11β‐HSD1 in intact cells as an oxoreductase without changing intrinsic catalytic properties of 11β‐HSD1 by regenerating NADPH in the ER‐lumen.
Biochemical engineering of the N‐acyl side chain of sialic acid leads to increased calcium influx from intracellular compartments and promotes differentiation of HL60 cells
Authors: Horstkorte Rüdiger , Rau Kirstin , Laabs Stephan , Danker Kerstin , Reutter Werner
Published: July 2004

Sialylation of glycoconjugates is essential for mammalian cells. Sialic acid is synthesized in the cytosol from N‐acetylmannosamine by several consecutive steps. Using N‐propanoylmannosamine, a novel precursor of sialic acid, we are able to incorporate unnatural sialic acids with a prolonged N‐acyl side chain (e.g., N‐propanoylneuraminic acid) into glycoconjugates taking advance of the cellular sialylation machinery. Here, we report that unnatural sialylation of HL60‐cells leads to an increased release of intracellular calcium after application of thapsigargin, an inhibitor of SERCA Ca2+‐ATPases. Furthermore, this increased intracellular calcium concentration leads to an increased adhesion to fibronectin. Finally, we observed an increase of the lectin galectin‐3, a marker of monocytic differentiation of HL60‐cells.
Characterisation of the Rab binding properties of Rab coupling protein (RCP) by site‐directed mutagenesis
Authors: Lindsay Andrew J , McCaffrey Mary W
Published: July 2004

Rab coupling protein (RCP) is a member of the Rab11‐family of interacting proteins (Rab11‐FIPs). Family members are characterised by their ability to interact with Rab11. This property is mediated by a conserved Rab binding domain (RBD) located at their carboxy‐termini. Several Rab11‐FIPs can also interact with other small GTPases. RCP interacts with Rab4 in addition to Rab11. To dissect out the individual properties of the Rab4 and Rab11 interactions with RCP, conserved amino acids within the RBD of RCP were mutated by site‐directed mutagenesis. The effect of these mutations on Rab4 and Rab11 binding, and the intracellular localisation of RCP, was examined. Our results indicate that Rab11, rather than Rab4, mediates the intracellular localisation of RCP, and that the class I Rab11‐FIPs compete for binding to Rab11.
Deglacial and postglacial climate history in east-central Isla Grande De Chiloé, Southern Chile (43°S)
Authors: Abarzúa Ana M. , Villagrán Carolina , Moreno Patricio I.
Published: July 2004

Palynologic and stratigraphic data from Laguna Tahui (42°50′S, 73°30′W) indicate cool–temperate and humid conditions there between 14,000 and 10,000 14C yr B.P., followed by warmer and drier-than-present conditions between 10,000 and 7000 14C yr B.P., and subsequent cooling and rise in precipitation over the last 5800 14C yr. The thermophilous Valdivian trees Eucryphia cordifolia and Caldcluvia paniculata reached their maximum abundance during the early Holocene warm–dry phase (10,000–7000 14C yr B.P.), followed by a rise in lake levels and reexpansion of North Patagonian conifers starting at 7000 and 5800 14C yr B.P., respectively. Variations in the stratigraphic and geographic distribution of temperate rainforests in southern Chile suggest multimillennial trends in temperature and westerly activity, which are spatially and temporally coherent with paleoclimate records from neighboring regions. Climate variability at millennial and submillennial time scales may account for the establishment and persistence of fine-scale mosaics of Valdivian and North Patagonian rainforest species in low- to mid-elevation communities since ∼5800 14C yr B.P.
Cancer in older patients
Authors: Beechey-Newman N , Kulkarni D
Published: July 2004

As the number of people living to reach old age increases, so the proportion of cancers presenting in this age group increases to an even greater degree. Although 70% of all cancers in men and women occur over the age of 65 and in the over-75s, who are perhaps more appropriately classified as ‘elderly’, the figures are still very high (46% of all cancers occur in women over 75 and 35% in men over 75). As a consequence, cancer is rapidly becoming a problem of late life, and the management of patients in old age is an important part of general oncology. The magnitude of the overlap between old age and cancer is increasing because of improved life expectancy, more sensitive methods of diagnosing cancer and the biological fact that most cancers occur more commonly with increasing age. It is interesting, however, to put these figures into a more general context by examining the different causes of death in older patients by decade.
What is person-centred care in dementia?
Authors: Brooker Dawn
Published: July 2004

The term person-centred care has become all-pervasive on the UK dementia care scene. It has been suggested that it has become synonymous with good quality care. It seems that any new approach in dementia care has to claim to be pc (person-centred) in order to be P.C. (politically correct). The term is used frequently in the aims and objectives for dementia care services and provision in the UK and the US, although what lies behind the rhetoric in terms of practice may be questionable.
Psychophysiologische Aspekte des Placeboeffekts bei Schmerz
Authors: Weiß Thomas
Published: July 2004

Zusammenfassung: Placeboeffekte entstehen aus einer komplexen Wechselwirkung innerhalb des neuronalen Netzwerks der Schmerzverarbeitung. Ein Hauptmechanismus für die Entstehung von Placeboeffekten ist Konditionierung, der zweite Hauptmechanismus ist die Erwartung einer erfolgreichen Therapie. Placeboeffekte werden zu einem erheblichen Teil über das endogene Opiatsystem vermittelt. Dies trifft für erwartungsbasierte Placeboeffekte vollständig zu, während opioidvermittelte konditionierte Effekte eine Teilkomponente darstellen. Des weiteren ist mindestens das dopaminerge System von Bedeutung. Für die neurobiologische Vermittlung der erwartungsbasierten Placeboeffekte scheint der rostrale anteriore cinguläre Kortex eine besondere Rolle zu spielen, was auf die enge Verknüpfung mit kognitiv-emotionalen Prozessen hinweist. Aus diesem Wissen heraus lassen sich Schlussfolgerungen für die gezielte Nutzung von Placeboeffekten in der Schmerztherapie, aber auch darüber hinaus ableiten.
A mixed layer carbon budget for the GasEx‐2001 experiment
Authors: Sabine Christopher L. , Feely Richard A. , Johnson Gregory C. , Strutton Peter G. , Lamb Marilyn F. , McTaggart Kristene E.
Published: July 2004

The GasEx‐2001 study took place aboard the NOAA Ship Ronald H. Brown in the eastern equatorial Pacific in February and March 2001. As part of this experiment, water column measurements were collected at noon each day near a drifting array of near‐surface instruments to examine the temporal evolution of the water column chemistry. These measurements were used to construct carbon mass balance estimates during this Lagrangian type study. Over a 13‐day period, the net drop in mixed layer dissolved inorganic carbon (DIC) was 6.5 μmol kg−1. The net precipitation during this period resulted in a DIC decrease of 1.2 μmol kg−1. Entrainment added 0.3 μmol kg−1 of DIC to the mixed layer from below giving a combined net physical effect that accounted for ∼14% of the total change. Biological new production removed 1.1 μmol kg−1 (17%) of DIC from the mixed layer. Air‐sea gas exchange had the largest impact on the DIC budget, accounting for 69% (4.5 μmol kg−1) of the total DIC removal from the mixed layer during this period. The estimated mean gas transfer velocity based on the DIC mass balance was 13.8 ± 3.6 cm hr−1 (K660 = 11.8 cm hr−1). The mean wind speed during this period was 6.0 ± 1.3 m s−1. This gas transfer velocity is in excellent agreement with estimates generated from atmospheric micro‐meteorological CO2 flux measurements collected on the same cruise. The agreement between the oceanic and atmospheric approaches supports the validity of the gas transfer velocities determined for the GasEx‐2001 experiment.
Three‐fluid model of the heating and acceleration of the fast solar wind
Authors: Ofman L.
Published: July 2004

A new three‐fluid, two‐dimensional, wave‐driven model that includes, for the first time, heat conduction, viscous, and resistive dissipation for protons and electrons in two‐dimensional coronal hole is presented. The fast solar wind model includes electron, proton, and He++ or O5+ ion fluids. The heating of the solar wind plasma due to MHD waves is modeled as follows: A broadband spectrum of low‐frequency Alfvén waves is launched from the base of the corona. The waves deposit momentum and heat into the plasma to produce the fast solar wind. The values of the resistivity and shear viscosity coefficients required to produce the hot and fast solar wind consistent with observations are orders of magnitude larger than classical values. An empirical heating term that represents the contribution of additional heating processes, such as resonant heating by ion cyclotron waves, is included for the heavy ions and for protons in three out of four cases in the present study.
Interplanetary magnetic field control of the location of substorm onset and auroral features in the conjugate hemispheres
Authors: Østgaard N. , Mende S. B. , Frey H. U. , Immel T. J. , Frank L. A. , Sigwarth J. B. , Stubbs T. J.
Published: July 2004

During 2001 and 2002, when the Imager for Magnetopause‐to‐Aurora Global Exploration (IMAGE) satellite had its apogee in the Northern Hemisphere and the Polar spacecraft, owing to the apsidal precession of its orbit, reached higher altitudes in the Southern Hemisphere, the two spacecraft offered a unique opportunity to study the aurora in the conjugate hemispheres simultaneously. Owing to the large fields of view of the Polar Visible Imaging System (VIS) Earth camera and the IMAGE‐FUV instruments, substorms and auroral features were imaged on a global scale in both hemispheres. We have identified five substorm onsets and several auroral features that can be unambiguously identified and compared in the two hemispheres. When mapped onto apex coordinates in the two hemispheres, we find that substorm onset locations and auroral features are usually not symmetric. The longitudinal displacement in one hemisphere compared with the other can be as much as 1.5 hours of local time (∼1500 km). For southward interplanetary magnetic field (IMF) the hemispherical asymmetry (ΔMLT) is strongly correlated with the IMF clock angle (θC) and a linear fit, ΔMLT = −0.017θC + 3.44, gives a correlation coefficient of 0.83 with a mean deviation of 0.4ΔMLT. These findings are interpreted as the magnetic tensions force acting on open magnetic field lines before reconnecting in the magnetotail. This can also be thought of as the IMF penetrating the magnetosphere.
On the use of the active infrared technique to infer heat and gas transfer velocities at the air‐water free surface
Authors: Atmane M. A. , Asher W. E. , Jessup A. T.
Published: July 2004

A comparison study of the experimental and theoretical transfer velocities of heat ands gas transfer at a wavy air‐water interface is undertaken using an active infrared technique and two gas tracers. Applying the surface renewal model formalism [Danckwerts, 1951], we find that the experimentally evaluated heat transfer velocity is roughly a factor of 2 higher than the transfer velocity of a gas with a low solubility in water when both are referenced to Sc = 600. Potential origins of such a discrepancy are investigated and we propose the use of the random eddy model [Harriott, 1962] to explain our results. The model is an extension of surface renewal to include the eddy approach distance as a new parameter. Numerical simulations of the random eddy model have been performed using a timescale evaluated from the Active Controlled Flux Technique (ACFT) and the characteristics of heat as well as the two gases used in the experiments (He and SF6). The simulation results show that the transfer velocities of two species, referenced to the same Schmidt number, are different and that their ratio depends on the average value of the approach distance and its distribution. The model as implemented in the present work also predicts changes in the Schmidt number exponent when the hydrodynamics conditions are varied.
Interannual to decadal variability in the southern Okhotsk Sea based on a new gridded upper water temperature data set
Authors: Minobe Shoshiro , Nakamura Makoto
Published: July 2004

A new gridded water‐temperature data set of upper 200 m depths (0, 50, 100, 200 m depths) for the Okhotsk Sea was produced using an optimal interpolation technique from 1950 to 1996 using oceanographic observations in the World Ocean Database 1998. Temperature variability at 50, 100 and 200 m depths in the southern Okhotsk Sea (south of 52°N) in the warm‐season (May–October) was investigated by an Empirical Orthogonal Function (EOF) analysis from 1958 to 1994, for which sufficient data exist for an EOF analysis. The first EOF mode has a monopole structure with the maximal amplitude in the Kuril Basin, and the corresponding Principal Component (PC) exhibits prominent quasi‐decadal variability. The first EOF mode is closely related with the wintertime (December–February) sea surface temperature anomalies over the subarctic front or Oyashio front in the North Pacific, and with wintertime Sea level Pressure (SLP) differences between northern Eurasia and the northern North Pacific. This suggests that the temperature changes in the Okhotsk Sea are caused by changes in the strength of the Asian winter monsoon, which are associated with the SLP difference. A quasi‐decadal oscillation, similar to that of the PC‐1, is observed in the SLP difference since the 1960s, and shared by the Polar/Eurasian (POL) pattern, Arctic Oscillation (AO) and North Atlantic Oscillation (NAO). Some hints of the relating variability are observed in coastal sea level difference between Wakkanai and Abashiri, which was used as a proxy for transport in the Soya Warm Current. Also, some features of sea ice extents co‐vary with the PC‐1.
Dense water formation on the northwestern shelf of the Okhotsk Sea: 2. Quantifying the transports
Authors: Shcherbina Andrey Y. , Talley Lynne D. , Rudnick Daniel L.
Published: July 2004

A combination of direct bottom mooring measurements, hydrographic and satellite observations, and meteorological reanalysis was used to estimate the rate of formation of Dense Shelf Water (DSW) due to brine rejection on the Okhotsk Sea northwestern shelf and the rate of export of DSW from this region. On the basis of remote sensing data, an estimated 8.6 × 1012 m3 of DSW was formed during the winter of 1999–2000, resulting in a mean annual production rate of 0.3 Sv. According to direct observations, the export rate of DSW during this period varied from negligibly small in autumn to 0.75 ± 0.27 Sv in winter (January–February), to 0.34 ± 0.12 Sv in spring (March–April). From these observations the mean annual export rate can be estimated to be 0.27 Sv. The same relationships used to obtain the integral estimates were also applied differentially using an advective approach incorporating realistic flow and heat flux fields, which allowed direct comparison with the moored observations. The comparison highlights the importance of along‐shelf advection and cross‐shelf eddy transport to the accurate parameterization of DSW formation.
Laboratory measurements of the W band (3.2 mm) properties of phosphine (PH3) and ammonia (NH3) under simulated conditions for the outer planets
Authors: Mohammed Priscilla N. , Steffes Paul G.
Published: July 2004

A model, based on the Van Vleck‐Weisskopf line shape, was developed for the centimeter‐wavelength opacity of PH3, which provides an order of magnitude improvement over previous models [Hoffman et al., 2001]. New laboratory measurements indicate that the model is also accurate at 94 GHz (3.2 mm) under conditions for the outer planets. Measurements of the opacity and refractivity of PH3 in a hydrogen/helium (H2/He) atmosphere were conducted at 94 GHz (3.2 mm) at pressures of 0.5 and 2 bars and at temperatures of 293 K and 213 K. Additionally, new high‐precision laboratory measurements of the opacity and refractivity of NH3 in an H2/He atmosphere were conducted at the same frequency at pressures from 0.5 to 2 bars and at temperatures of 204 K, 211 K, and 290 K. Results show that existing models, which predict NH3 opacity in an H2/He environment, understate the absorption due to the pressure broadened rotational lines. A new model is proposed for use at 94 GHz (3.2 mm) which uses a Ben‐Reuven line shape [Ben‐Reuven, 1966] for the inversion lines and a Kinetic line shape [Gross, 1955] for the rotational lines. Results of measurements of both PH3 and NH3 can be used to better interpret maps of Saturn's emission at this wavelength and can potentially be used to deduce spatial variations in the abundances of both gases in the atmosphere of Saturn.
Footwall topographic development during continental extension
Authors: Densmore Alexander L. , Dawers Nancye H. , Gupta Sanjeev , Guidon Roman , Goldin Tamara
Published: July 2004

We examine the progressive development of footwall topography associated with a set of active normal faults in the northeastern Basin and Range Province of the western United States. Fault length and displacement increase monotonically from northeast to southwest in the study area, allowing us to track both variations in footwall morphology with increasing displacement and along‐strike changes in morphology on a single fault. We show that patterns of catchment area, footwall relief, and catchment outlet spacing vary predictably and are related to the growth of the range‐bounding normal fault array. In this semiarid region, full parsing of footwall drainage area and removal of antecedent topography do not occur until fault arrays grow beyond two crustal‐scale segments. Multiple‐segment faults with lengths of up to 150 km have footwall relief that is limited to ∼1000 m in the center of the footwall and that decays to zero at the fault tips over a length scale of ∼15 km. We hypothesize that this relatively uniform footwall relief is erosionally limited and reflects the efficacy of surface processes in removing footwall material in the center of the footwall. If the fault array grows by relatively steady propagation of the tips, we suggest that the 15 km length scale required to reach uniform relief is related to a timescale of relief generation by the fault tip propagation rate. While such propagation rates are poorly known, an average rate of 10 mm yr−1 would imply footwall relief generation over a timescale of ∼1 Myr.
SO2 emissions from basaltic eruptions, and the excess sulfur issue
Authors: Sharma K. , Blake S. , Self S. , Krueger A. J.
Published: July 2004

Volcanic SO2 can affect the Earth's environment. Where no direct measurements of SO2 in the atmosphere are available, a petrologic method of assessing sulfur release from the magma must be used. However, in studies of arc‐derived eruptions, satellite‐based measurements of SO2 emissions using Total Ozone Mapping Spectrometer (TOMS) data are orders of magnitude greater than those calculated petrologically, implying that a separate S‐rich gas phase in the magma chamber may be responsible for the excess sulfur. We test whether this applies in other settings. For Icelandic and Hawaiian basalts we find that petrologic SO2 values are comparable to measurements of SO2 by TOMS. Thus, for non‐arc basalts, the petrologic method gives reliable estimates of SO2 released. The implied absence of excess sulfur in non‐arc basaltic magmas is a reflection of source magma conditions, notably lower fO2 and volatile contents than arc magmas, inhibiting the exsolution of a S‐rich gas prior to eruption.
Merging information from different resources for new insights into climate change in the past and future
Authors: Huang Shaopeng
Published: July 2004

An understanding of climate history prior to industrialization is crucial to understanding the nature of the 20th century warming and to predicting the climate change in the near future. This study integrates the complementary information preserved in the global database of borehole temperatures [Huang et al., 2000], the 20th century meteorological record [Jones et al., 1999], and an annually resolved multi proxy model [Mann et al., 1999] for a more complete picture of the Northern Hemisphere temperature change over the past five centuries. The integrated reconstruction shows that the 20th century warming is a continuation to a long‐term warming started before the onset of industrialization. However, the warming appears to have been accelerated towards the present day. Analysis of the reconstructed temperature and radiative forcing series [Crowley, 2000] offers an independent estimate of the transient climate‐forcing response rate of 0.4–0.7 K per Wm−2 and predicts a temperature increase of 1.0–1.7 K in 50 years.
Summer cooling of the Arabian Sea during contrasting monsoons
Authors: Vinayachandran P. N.
Published: July 2004

Temperature and salinity profiles from the upper ocean in the Arabian Sea, measured by Argo floats, together with satellite derived sea surface temperature and winds are used to examine the response of the Arabian Sea to the contrasting monsoons of 2002 and 2003. The Indian summer monsoon rainfall of 2002 was unusually low compared to a near normal monsoon during 2003. Contrary to the general belief that a stronger Indian summer monsoon causes larger summer cooling and leaves behind a cooler Arabian Sea, we find that the Arabian Sea was warmer during 2003 summer than during 2002. The delayed onset of the summer monsoon during 2003 led to this difference. Although the winds during 2003 July were stronger it was not able to compensate for the weak and delayed onset of southwesterlies during 2003. This implies that a strong summer monsoon over India does not necessary imply a larger thermodynamic impact on the Arabian Sea. The strength and duration of the southwesterlies are the decisive parameters for the summer cooling of the Arabian Sea.
Tectonic forcing of shelf‐ramp depositional architecture, Laguna Madre‐Tuxpan Shelf, western Gulf of Mexico
Authors: Wawrzyniec Tim F. , Ambrose W. , Aranda‐Garcia M. , Romano U. H.
Published: July 2004

Analysis of seismic reflection data reveals the existence of a major listric fault that accommodates most of the Neogene extension of the Laguna Madre‐Tuxpan shelf of the western Gulf of Mexico. The variation of related growth strata, the profile of the modern shelf‐slope transition, the linear gradient of shelf extension (as well as basin accommodation) along the trace of the fault support a hypothesis that sediment loading along the northern part of the fault drives fault motion and influences sediment distribution along the southern end of the fault. In particular, where kinematic accommodation appears to outpace sediment supply, sedimentation is maximized along a shelf‐ramp system and not the shelf‐slope transition.
Inertial currents estimated from surface trajectories of ARGO floats
Authors: Park Jong Jin , Kim Kuh , Crawford William R.
Published: July 2004

We have developed an analysis method to determine the amplitude of inertial motion from surface trajectory data of ARGO profiling floats. This method gives an estimate of inertial current speed and phase from satellite fixes transmitted while a float drifts at the surface, over a time which is typically about one local inertial period. The error of this method is about 3.4 cm/sec for data records with at least 6 positions with accuracy of 500 m, spanning longer than 68% of the inertial period, whereas inertial amplitudes are as large as 40 cm/sec with a median of about 12.0 cm/sec in the Japan/East Sea. Globally distributed ARGO floats could provide useful information on the co‐variability of wind‐forced inertial currents and mixed layer depths in the ocean.
Dynamics of unusual debris flows on Martian sand dunes
Authors: Miyamoto Hideaki , Dohm James M. , Baker Victor R. , Beyer Ross A. , Bourke Mary
Published: July 2004

Gullies that dissect sand dunes in Russell impact crater often display debris flow‐like deposits in their distal reaches. The possible range of both the rheological properties and the flow rates are estimated using a numerical simulation code of a Bingham plastic flow to help explain the formation of these features. Our simulated results are best explained by a rapid debris flow. For example, a debris flow with the viscosity of 102 Pa s and the yield strength of 102 Pa can form the observed deposits with a flow rate of 0.5 m3/s sustained over several minutes and total discharged water volume on the order of hundreds of cubic meters, which may be produced by melting a surface layer of interstitial ice within the dune deposits to several centimeters depth.
The sine-Gordon equation in reversed-field pinch experiments
Authors: Shohet J. L. , Barmish B. R. , Ebraheem H. K. , Scott A. C.
Published: July 2004

The focal point of this paper is a nonlinear model which describes localized magnetohydrodynamic modes in reversed-field pinch experiments. To date, nearly all experimental and theoretical work in this area have relied on the use of Fourier decomposition of spatial variations as a function of time. Moreover, due to the complexity of this nonlinear problem, previous work is restricted to the analysis of a relatively small number of modes. In contrast, the model studied in this paper, based on the sine-Gordon equation, addresses the full nonlinearity, does not rely on Fourier decomposition and does not require the range of the nonlinearity to be small. A specific consequence of working with the full nonlinearity is the existence of solitary waves in dispersive media. These solitary waves, a key part of the model, are used to describe the so-called slinky-mode propagating in the plasma. To this end, a remarkable resemblance is seen between the wave forms obtained from experiments and the mathematical predictions of the model.
Wave phenomena, hot electrons, and enhanced plasma production in a helicon discharge in a converging magnetic field
Authors: Virko V. F. , Shamrai K. P. , Virko Yu. V. , Kirichenko G. S.
Published: July 2004

Plasma characteristics and wave structures are examined for an m=0 helicon discharge operated in a nonuniform magnetic field. With the increase of the magnetic field gradient in the antenna region, plasma production rapidly grows and the density maximum moves downstream, towards the stronger field. Probe and optical measurements reveal a narrow layer of hot electrons (with temperature up to 7 eV) that extends far from the antenna along converging magnetic lines. A radially small-scale wave structure with peaks of the order of a few skin lengths is detected within the hot layer by magnetic and capacitive probes. Computations based on a simple plane model show that the inclination of the magnetic field lines to the plasma surface underneath the antenna is a critical factor for the distribution of the rf power absorption and for the formation of the small-scale structure. If the inclination angle exceeds the resonance group velocity angle, the near antenna absorption falls and the power flux penetrates deep into plasma along the magnetic lines. The fine wave pattern is explained considering the propagation characteristics of the helicon waves. Directional and extended power deposition together with high electron conductivity along the magnetic lines are argued to cause generation of hot electrons and enhanced plasma production.
On the trapping of Alfvén waves in the polar region of a compact gravitating object
Authors: Mofiz U. A.
Published: July 2004

Alfvén wave propagation in the polar region of compact gravitating objects is studied using linear magnetohydrodynamic equations. The temperature is considered as isothermal in several Schwarzschild radii. The study demonstrates reflection and trapping of the wave from the steep gradient region of Alfvén speed. The trapping efficiency depends sensitively on a dimensionless parameter βg which is proportional to the mass and inversely proportional to the temperature of the plasma. The Alfvén wave in the polar region of a compact gravitating object is found to be trapped by reflection due to plasma density and magnetic field variation with the height. The reflection occurs at the frequency less than some critical frequency determining the steepness of the Alfvén speed gradient depending on the temperature. Particle acceleration by Alfvén waves is also examined.
Shouldn’t there be an antithesis to quantization?
Authors: Galapon Eric A.
Published: July 2004

We raise the possibility of developing a theory of constructing quantum dynamical observables independent from quantization and deriving classical dynamical observables from pure quantum mechanical consideration. We do so by giving a detailed quantum mechanical derivation of the classical time of arrival at arbitrary arrival points for a particle in one dimension.
The influence of an external magnetic field on a radio frequency excited CO2 laser
Authors: Sohbatzadeh F. , Tavassoli H. , Latifi H.
Published: July 2004

The influence of a dc external magnetic field B0 on the output power of a rf excited CO2 laser is considered. The voltage-current density characteristic curve, electron temperature, deposited power, and gas mixture temperature of the plasma are numerically investigated in the presence of the external magnetic field. The electric discharge of the magnetized rf excited CO2 laser is seen to be stable. It is shown that the deposited power into the plasma increases with increasing magnetic field intensity. Mean temperature of the gas mixture of the magnetized rf excited CO2 laser is computed as a function of B0, which is substantially increased at a relatively strong B0. An experimental setup is conducted to measure the output power of a rf excited CO2 laser in the presence of B0. It is found by applying B0 upon the laser the output power increases.
Analyticity of the SRB measure of a lattice of coupled Anosov diffeomorphisms of the torus
Authors: Bonetto F. , Falco P. , Giuliani A.
Published: July 2004

We consider the “thermodynamic limit” of a d-dimensional lattice of hyperbolic dynamical systems on the 2-torus, interacting via weak and nearest neighbor coupling. We prove that the SRB measure is analytic in the strength of the coupling. The proof is based on symbolic dynamics techniques that allow us to map the SRB measure into a Gibbs measure for a spin system on a (d+1)-dimensional lattice. This Gibbs measure can be studied by an extension (decimation) of the usual “cluster expansion” techniques.
Net charge of a conducting microsphere embedded in a thermal plasma
Authors: Kanapathipillai M. , Mulser P. , Hoffmann D. H. H. , Schlegel T. , Maron Y. , Sauerbrey R.
Published: July 2004

The knowledge of the net charge of conducting spheres has gained much interest in the context of high power laser interaction with clusters, dust, impurities, aerosols, and small liquid droplets. Contrary to a general supposition based on linearized plasma quasineutrality it is shown that in electronic thermal equilibrium spheres of one Debye length radius lose almost all free electrons, hence are highly charged. Quasineutrality is approximately reached for pellet sizes R exceeding 30 times the Debye length. In order to gain an estimate of the net charge of nonspherical particles the equilibrium charge is determined in slab geometry for the same parameters.