Residual bias in a multiphase flow model calibration and prediction
E. P. Poeter, R.H. Johnson
2002, Acta Universitatis Carolinae, Geologica (46) 208-212
When calibrated models produce biased residuals, we assume it is due to an inaccurate conceptual model and revise the model, choosing the most representative model as the one with the best-fit and least biased residuals. However, if the calibration data are biased, we may fail to identify an acceptable model...
Imaging the mantle beneath Iceland using integrated seismological techniques
R. M. Allen, G. Nolet, W. J. Morgan, K. Vogfjord, B. H. Bergsson, P. Erlendsson, G.R. Foulger, S. Jakobsdottir, B.R. Julian, M. Pritchard, S. Ragnarsson, R. Stefansson
2002, Journal of Geophysical Research B: Solid Earth (107) ESE 3-1-ESE 3-16
Using a combination of body wave and surface wave data sets to reveal the mantle plume and plume head, this study presents a tomographic image of the mantle structure beneath Iceland to 400 km depth. Data comes primarily from the PASSCAL-HOTSPOT deployment of 30 broadband instruments over a period of...
Nitrate stable isotopes: Tools for determining nitrate sources among different land uses in the Mississippi River Basin
Cecily C.Y. Chang, C. Kendall, S. R. Silva, W.A. Battaglin, K. Campbell
2002, Canadian Journal of Fisheries and Aquatic Sciences (59) 1874-1885
A study was conducted to determine whether NO3 stable isotopes (δ15N and δ18O), at natural abundance levels, could discriminate among NO3 sources from sites with different land uses at the basin scale. Water samples were collected from 24 sites in the Mississippi River Basin...
Elevations of water-worn features on Mars: Implications for circulation of groundwater
M. H. Carr
2002, Journal of Geophysical Research E: Planets (107) 14-1-14-11
Central to the model of the evolution of the martian hydrosphere by Clifford and Parker [2001] is a permanent freezing of the planet at the end of the Noachian and recharge of the global groundwater system by basal melting of ice-rich polar deposits. Acquisition of MOLA data by Mars Global Surveyor provides a...
The 1999 eruption of Shishaldin Volcano, Alaska: Monitoring a distant eruption
C.J. Nye, T. E. C. Keith, J.C. Eichelberger, T. P. Miller, S.R. McNutt, S. Moran, D.J. Schneider, J. Dehn, J.R. Schaefer
2002, Bulletin of Volcanology (64) 507-519
Shishaldin Volcano, in the central Aleutian volcanic arc, became seismically restless during the summer of 1998. Increasing unrest was monitored using a newly installed seismic network, weather satellites, and rare local visual observations. The unrest culminated in large eruptions on 19 April and 22-23 April 1999. The opening phase of...
The potential of combining ion trap/MS/MS and TOF/MS for identification of emerging contaminants
I. Ferrer, E. T. Furlong, C.E. Heine, E.M. Thurman
2002, Conference Paper, Proceedings 50th ASMS Conference on Mass Spectrmetry and Allied Topics
The use of a method combining ion trap tandem mass spectrometry (MS/MS) and time of flight mass spectrometry (TOF/MS) for identification of emerging contaminates was discussed. The two tools together complemented each other in sensitivity, fragmentation and accurate mass determination. Liquid chromatography/electrospray ionization/ion-trap tandem mass spectrometry (LC/ESI/MS/MS), in positive ion...
Detrital zircon provenance analysis of the Great Valley Group, California: Evolution of an arc-forearc system
K. DeGraaff-Surpless, S.A. Graham, J. L. Wooden, M.O. McWilliams
2002, Geological Society of America Bulletin (114) 1564-1580
The improved resolution of sediment provenance from detrital zircon analysis of Great Valley stratigraphy enables recognition of previously undocumented arc magmatism and the evolution of regional drainage systems within the Cretaceous arc-forearc system related to uplift, magmatism, and structure in the arc. Great Valley detrital zircon age data confirm previous...
Topographic stress perturbations in southern Davis Mountains, west Texas 1. Polarity reversal of principal stresses
W. Z. Savage, R. H. Morin
2002, Journal of Geophysical Research B: Solid Earth (107) ETG 5-1-ETC 5-15
We have applied a previously developed analytical stress model to interpret subsurface stress conditions inferred from acoustic televiewer logs obtained in two municipal water wells located in a valley in the southern Davis Mountains near Alpine, Texas. The appearance of stress-induced breakouts with orientations that shift by 90° at two...
Supporting user-defined granularities in a spatiotemporal conceptual model
V. Khatri, S. Ram, R.T. Snodgrass, G. M. O’Brien
2002, Conference Paper, Annals of Mathematics and Artificial Intelligence
Granularities are integral to spatial and temporal data. A large number of applications require storage of facts along with their temporal and spatial context, which needs to be expressed in terms of appropriate granularities. For many real-world applications, a single granularity in the database is insufficient. In order to support...
Statistical characteristics of xenoliths in the Antioch kimberlite pipe, Marshall County, northeastern Kansas
S. Kotov, Pieter Berendsen
2002, Natural Resources Research (11) 289-297
Geometrical characteristics of xenoliths in the Antioch kimberlite pipe have been considered in statistical terms. A method of conversion of 2D intersections to 3D dimensions was used. It has been shown that the Rosin-Rammler distribution of mass leads to the Weibull distribution of sizes, whereas a fractal distribution of sizes...
A multiisotope C and N modeling analysis of soil organic matter turnover and transport as a function of soil depth in a California annual grassland soil chronosequence
W.T. Baisden, Ronald Amundson, D.L. Brenner, A.C. Cook, C. Kendall, J.W. Harden
2002, Global Biogeochemical Cycles (16) 82-1-82-26
We examine soil organic matter (SOM) turnover and transport using C and N isotopes in soil profiles sampled circa 1949, 1978, and 1998 (a period spanning pulse thermonuclear 14C enrichment of the atmosphere) along a 3‐million‐year annual grassland soil chronosequence. Temporal differences in soil Δ14C profiles indicate that inputs of recently...
Modified Biot-Gassmann theory for calculating elastic velocities for unconsolidated and consolidated sediments
Myung W. Lee
2002, Marine Geophysical Research (23) 403-412
The classical Biot-Gassmann theory (BGT) generally overestimates shear-wave velocities of water-saturated sediments. To overcome this problem, a new theory is developed based on BGT and on the velocity ratio as a function of G(1−φ)n, where φ is porosity and n and G are constants. Based on laboratory data measured at ultrasonic frequencies, parameters for the...
Great Holocene floods along Jokulsa a Fjollum, north Iceland
R. B. Waitt
2002, Book chapter, Flood and megaflood processes and deposits: Recent and ancient examples
Jökulsá á Fjöllum, Iceland's largest glacial river, drains from Vatnajökull icecap northward to the sea along a broad low that includes an active volcanic belt. Geomorphic features along this path reveal an ancient discharge of water large enough to fill the river valley and spill among a plexus of lows...
Locally refined block-centered finite-difference groundwater models: Evaluation of parameter sensitivity and the consequences for inverse modelling and predictions
S. Mehl, M. C. Hill
2002, Acta Universitatis Carolinae, Geologica (46) 199-203
Models with local grid refinement, as often required in groundwater models, pose special problems for model calibration. This work investigates the calculation of sensitivities and performance of regression methods using two existing and one new method of grid refinement. The existing local grid refinement methods considered are (1) a variably...
Improving the analysis of slug tests
C.D. McElwee
2002, Journal of Hydrology (269) 122-133
This paper examines several techniques that have the potential to improve the quality of slug test analysis. These techniques are applicable in the range from low hydraulic conductivities with overdamped responses to high hydraulic conductivities with nonlinear oscillatory responses. Four techniques for improving slug test analysis will be discussed: use...
Ontogenetic behavior and migration of Volga River Russian sturgeon, Acipenser gueldenstaedtii, with a note on adaptive significance of body color
B. Kynard, P. Zhuang, L. Zhang, T. Zhang, Z. Zhang
2002, Environmental Biology of Fishes (65) 411-421
We conducted laboratory experiments with Volga River Russian sturgeon, Acipenser gueldenstaedtii, to develop a conceptual model of early behavior. We daily observed fish from day-0 (embryos, first life interval after hatching) to day-29 feeding larvae for preference of bright habitat and cover, swimming distance above the bottom, up- and downstream...
Zoned chondrules in Semarkona: Evidence for high-and low-temperature processing
Jeffrey N. Grossman, C. M. O’D. Alexander, Jianhua Wang, Adrian J. Brearley
2002, Meteoritics and Planetary Science (37) 49-73
At least 15% of the low-FeO chondrules in Semarkona (LL3.0) have mesostases that are concentrically zoned in Na, with enrichments near the outer margins. We have studied zoned chondrules using electron microprobe methods (x-ray mapping plus quantitative analysis), ion microprobe analysis for trace elements and hydrogen isotopes, cathodoluminescence imaging, and...
Migration and habitats of diadromous Danube River sturgeons in Romania: 1998-2000
B. Kynard, R. Suciu, Martin Horgan
2002, Journal of Applied Ichthyology (18) 529-535
Upstream migrant adults of stellate sturgeon, Acipenser stellatus (10 in 1998, 43 in 1999) and Russian sturgeon, A. gueldenstaedtii (three in 1999) were captured at river km (rkm) 58-137, mostly in the spring, and tagged with acoustic tags offering a reward for return. The overharvest was revealed by tag returns...
Distinguishing sediment waves from slope failure deposits: Field examples, including the 'humboldt slide', and modelling results
H.J. Lee, J.P.M. Syvitski, G. Parker, Daniel L. Orange, J. Locat, E. W. H. Hutton, J. Imran
2002, Marine Geology (192) 79-104
Migrating sediment waves have been reported in a variety of marine settings, including submarine levee-fan systems, floors of fjords, and other basin or continental slope environments. Examination of such wave fields reveals nine diagnostic characteristics. When these characteristics are applied to several features previously attributed to submarine landslide deformation, they...
Model-based estimation of individual fitness
William A. Link, Evan G. Cooch, Emmanuelle Cam
2002, Journal of Applied Statistics (29) 207-224
Fitness is the currency of natural selection, a measure of the propagation rate of genotypes into future generations. Its various definitions have the common feature that they are functions of survival and fertility rates. At the individual level, the operative level for natural selection, these rates must be understood as...
Late quaternary evolution of the Orinoco Delta, Venezuela
A.G. Warne, E.H. Guevara, A. Aslan
2002, Journal of Coastal Research (18) 225-253
The modern Orinoco Delta is the latest of a series of stacked deltas that have infilled the Eastern Venezuelan Basin (EVB) since the Oligocene. During the late Pleistocene sea-level lowstand (20,000 to 16,000 yrs BP), bedrock control points at the position of the present delta apex prevented the river channel...
Development of sulfide calibration standards for the laser ablation inductively-coupled plasma mass spectrometry technique
S. A. Wilson, W.I. Ridley, A.E. Koenig
2002, Journal of Analytical Atomic Spectrometry (17) 406-409
The requirements of standard materials for LA-ICP-MS analysis have been difficult to meet for the determination of trace elements in sulfides. We describe a method for the production of synthetic sulfides by precipitation from solution. The method is detailed by the production of approximately 200 g of a material, PS-1,...
Increasing risk of great floods in a changing climate
P. C. D. Milly, R.T. Wetherald, K.A. Dunne, T.L. Delworth
2002, Nature (415) 514-517
Radiative effects of anthropogenic changes in atmospheric composition are expected to cause climate changes, in particular an intensification of the global water cycle with a consequent increase in flood risk. But the detection of anthropogenically forced changes in flooding is difficult because of the substantial natural variability; the dependence of...
Interspecific differences in susceptibility to competition and predation in a species-pair of larval amphibians
Susan C. Walls, David G. Taylor, Charlena M. Wilson
2002, Herpetologica (58) 104-118
Fundamental issues in the study of predator-prey interactions include addressing how prey coexist with their predators and, moreover, whether predators promote coexistence among competing prey. We conducted a series of laboratory experiments with a freshwater assemblage consisting of two predators that differed in their foraging modes (a crayfish, Procambarus sp., and...
Stable carbon and nitrogen isotope composition of aquatic and terrestrial plants of the San Francisco Bay estuarine system
J. E. Cloern, E. A. Canuel, D. Harris
2002, Limnology and Oceanography (47) 713-729
We report measurements of seasonal variability in the C‐N stable isotope ratios of plants collected across the habitat mosaic of San Francisco Bay, its marshes, and its tributary river system. Analyses of 868 plant samples were binned into 10 groups (e.g., terrestrial riparian, freshwater phytoplankton, salt marsh)...
