Microvariability in Seyfert galaxies
M.T. Carini, J.C. Noble, H.R. Miller
2003, Astronomical Journal (125) 1811-1816
We present the results of a search for microvariability in a sample of eight Seyfert galaxies. Microvariability (i.e., variations occurring on timescales of tens of minutes to hours) has been conclusively demonstrated to exist in the class of active galactic nuclei (AGNs) known as blazars. Its existence in other classes...
Influence of flow and temperature on survival of wild subyearling fall chinook salmon in the Snake River
W.P. Connor, H.L. Burge, J.R. Yearsley, T.C. Bjornn
2003, North American Journal of Fisheries Management (23) 362-375
Summer flow augmentation to increase the survival of wild subyearling fall chinook salmon Oncorhynchus tshawytscha is implemented annually to mitigate for the development of the hydropower system in the Snake River basin, but the efficacy of this practice has been disputed. We studied some of the factors affecting survival of...
The usefulness of GPS telemetry to study wolf circadian and social activity
S.B. Merrill, Mech L. David
2003, Wildlife Society Bulletin (31) 947-960
This study describes circadian and social movement patterns of 9 wolves and illustrates capabilities and limitations of Global Positioning System (GPS) telemetry for analysis of animal activity patterns. Wolves were studied at the Camp Ripley National Guard Training Site in Little Falls, Minnesota, and were captured via helicopter net-gunning. All...
Effect of swimming activity on relative weight and body composition of juvenile rainbow trout
D.G. Simpkins, W.A. Hubert, Del Rio, D.C. Rule
2003, North American Journal of Fisheries Management (23) 283-289
Fisheries managers often assess body condition using relative weight (Wr) because it provides a comparative measure of fish plumpness among individuals and populations. However, it is not known whether the morphological information that Wr summarizes reflects physiological measures, such as relative lipid reserves, in rainbow trout Oncorhynchus mykiss. The purpose...
Sub-ice volcanoes and ancient oceans/lakes: A Martian challenge
M. G. Chapman
2003, Global and Planetary Change (35) 185-198
New instruments on board the Mars Global Surveyor (MGS) spacecraft began providing accurate, high-resolution image and topography data from the planet in 1997. Though data from the Mars Orbiter Laser Altimeter (MOLA) are consistent with hypotheses that suggest large standing bodies of water/ice in the northern lowlands in the planet's...
Using noble gases to investigate mountain-front recharge
A. H. Manning, D. K. Solomon
2003, Conference Paper, Journal of Hydrology
Mountain-front recharge is a major component of recharge to inter-mountain basin-fill aquifers. The two components of mountain-front recharge are (1) subsurface inflow from the mountain block (subsurface inflow), and (2) infiltration from perennial and ephemeral streams near the mountain front (stream seepage). The magnitude of subsurface inflow is of central...
Modeling Np and Pu transport with a surface complexation model and spatially variant sorption capacities: Implications for reactive transport modeling and performance assessments of nuclear waste disposal sites
P. D. Glynn
2003, Computers & Geosciences (29) 331-349
One-dimensional (1D) geochemical transport modeling is used to demonstrate the effects of speciation and sorption reactions on the ground-water transport of Np and Pu, two redox-sensitive elements. Earlier 1D simulations (Reardon, 1981) considered the kinetically limited dissolution of calcite and its effect on ion-exchange reactions (involving 90Sr, Ca, Na, Mg and...
Tidal-bundle sequences in the Jordan Sandstone (Upper Cambrian), southeastern Minnesota, U.S.A.: Evidence for tides along inboard shorelines of the Sauk Epicontinental Sea
C.H. Tape, Clinton A. Cowan, Anthony C. Runkel
2003, Journal of Sedimentary Research (73) 354-366
This study documents for the first time tidal bundling in a lower Paleozoic sheet sandstone from the cratonic interior of North America, providing insights into the hydrodynamics of ancient epicontinental seas. The Jordan Sandstone (Upper Cambrian) in the Upper Mississippi Valley contains large-scale planar tabular cross-sets with tidal-bundle sequences, which...
Interactive effects of redox intensity and phosphate availability on growth and nutrient relations of Cladium jamaicense (Cyperaceae)
J. Lissner, I.A. Mendelssohn, B. Lorenzen, H. Brix, K.L. McKee, S.L. Miao
2003, American Journal of Botany (90) 736-748
Expansion of Typha domingensis into areas previously dominated by Cladium jamaicensein the Florida Everglades has been linked to anthropogenic phosphorus (P) enrichment and increased hydroperiod. The principal stress factor for plants in flooded soils is biochemical reduction, the intensity of which is measured as redox potential (Eh). The objective of this study was...
Benefits and costs of increased levels of corticosterone in seabird chicks
A.S. Kitaysky, E.V. Kitaiskaia, John F. Piatt, J.C. Wingfield
2003, Hormones and Behavior (43) 140-149
Seabird chicks respond to food shortages by increasing corticosterone (cort) secretion, which is probably associated with fitness benefits and costs. To examine this, we experimentally increased levels of circulating cort in captive black-legged kittiwake chicks fed ad libitum. We found that cort-implanted chicks begged more frequently and were more aggressive...
Sex differences in the thermoregulation and evaporative water loss of a heterothermic bat, Lasiurus cinereus, during its spring migration
P.M. Cryan, B. O. Wolf
2003, Journal of Experimental Biology (206) 3381-3390
This study quantifies sex differences in thermoregulation and water loss of a small (20-35 g) insectivorous heterothermic mammal, the hoary bat Lasiurus cinereus, during its spring migration. We measured body temperature, metabolic rate and evaporative water loss, and calculated wet thermal conductance, for bats exposed to air temperatures ranging from...
Beaver (Castor canadensis) in heavily browsed environments
Bruce W. Baker
2003, Lutra (46) 173-181
Beaver (Castor canadensis) populations have declined or failed to recover in heavily browsed environments. I suggest that intense browsing by livestock or ungulates can disrupt beaver-willow (Salix spp.) mutualisms that likely evolved under relatively low herbivory in a more predator-rich environment, and that this interaction may explain beaver and willow...
[Book review] Nebraska birds in recorded history
F.L. Knopf
2003, Prairie Naturalist (35) 129-131
Review of: "Birds of the Untamed West" by James E. Ducey. 2000. Omaha, Nebraska: Making History Press. 299 pages. $25.00 (paper)....
The crisis discipline of conservation medicine
K. D. Lafferty
2003, Conservation Biology (17) 1859-1860
Review of: Conservation Medicine: Ecological Health in Practice. Aguirre, A. A., R. S. Ostfeld, G. M. Tabor, C. House, and M. C. Pearl, editors. 2002. Oxford University Press, New York. 431 pp. $45.00. ISBN 0–195–15093....
Effects of river flow regime on cottonwood leaf litter dynamics in semi-arid northwestern Colorado
D.C. Andersen, S. M. Nelson
2003, Southwestern Naturalist (48) 188-201
We compared production and breakdown of Fremont cottonwood (Populus deltoides wislizenii) leaf litter at matched floodplain sites on the regulated Green River and unregulated Yampa River in semi-arid northwestern Colorado. Litter production under trees was similar at sites in 1999 (250 g/m2, oven-dry) but lower in 2000 (215 and 130...
Physiological and morphological response patterns of Populus deltoides to alluvial groundwater
D.J. Cooper, D.R. D’Amico, M. L. Scott
2003, Environmental Management (31) 215-226
We examined the physiological and morphological response patterns of plains cottonwood [Populus deltoides subsp. monilifera (Aiton) Eck.] to acute water stress imposed by groundwater pumping. Between 3 and 27 July 1996, four large pumps were used to withdraw alluvial groundwater from a cottonwood forest along the...
Seasonal distribution of migratory tree bats (Lasiurus and Lasionycteris) in North America
Paul M. Cryan
2003, Journal of Mammalogy (84) 579-593
Despite evidence of migration in North American tree bats (genera Lasiurus and Lasionycteris), details regarding seasonal movements in these widely distributed species are few. This study attempted to clarify patterns of seasonal distribution by mapping museum occurrence records by month. Monthly changes in the distribution of records indicate seasonal movements...
Shallow-velocity models at the Kilauea Volcano, Hawaii, determined from array analyses of tremor wavefields
G. Saccorotti, B. Chouet, P. Dawson
2003, Geophysical Journal International (152) 633-648
The properties of the surface wavefield at Kilauea Volcano are analysed using data from small-aperture arrays of short-period seismometers deployed in and around the Kilauea caldera. Tremor recordings were obtained during two Japan-US cooperative experiments conducted in 1996 and 1997. The seismometers were deployed in three semi-circular arrays with apertures...
Seasonal and spatial distribution of bacterial biomass and the percentage of viable cells in a reservoir of Alabama
T.E. Tietjen, R.G. Wetzel
2003, Journal of Plankton Research (25) 1521-1534
Spatial community dynamics of bacterioplankton were evaluated along the length of the former stream channel of Elledge Lake, a small reservoir in western Alabama. The reservoir was strongly stratified from April to October with up to a 10??C temperature difference across the 1 m deep metalimnion. Bacterial biomass was highest...
Simulating ground water-lake interactions: Approaches and insights
R. J. Hunt, H.M. Haitjema, J. T. Krohelski, D. T. Feinstein
2003, Ground Water (41) 227-237
Approaches for modeling lake-ground water interactions have evolved significantly from early simulations that used fixed lake stages specified as constant head to sophisticated LAK packages for MODFLOW. Although model input can be complex, the LAK package capabilities and output are superior to methods that rely on a fixed lake stage...
Physiological characteristics of wild Atlantic salmon post-smolts during estuarine and coastal migration
S.O. Stefansson, B. Th Bjornsson, K. Sundell, G. Nyhammer, S. D. McCormick
2003, Journal of Fish Biology (63) 942-955
Changes were measured in some of the major physiological variables associated with seawater adaptability, growth and energetics in wild Atlantic salmon Salmo salar smolts and post-smolts migrating from the river and through the estuary, fjord and coastal areas in the River Orkla and the Trondheimsfjord, Norway during late May to...
Two-dimensional inverse and three-dimensional forward modeling of MT (magnetotelluric) data to evaluate the mineral potential of the Amphitheater Mountains, Alaska, USA
Louise Pellerin, Jeanine M. Schmidt, G. Michael Hoversten
2003, Conference Paper, Proceedings of the 3DEM-3 symposium: Three dimensional electromagnetics III: ASEG Special Publications 2003(1)
As part of an integrated geological and geophysical study to assess the mineral potential in the Amphitheater Mountains of south-central Alaska, USA, two magnetotelluric (MT) profiles were acquired during the summer of 2002. The two parallel MT lines, along with helicopter electromagnetic (HEM) and magnetic data acquired by the State...
Effect of analytical conditions in wavelength dispersive electron microprobe analysis on the measurement of strontium-to-calcium (Sr/Ca) ratios in otoliths of anadromous salmonids
Christian E. Zimmerman, Roger L. Nielsen
2003, Fishery Bulletin (101) 712-718
The use of strontium-to-calcium (Sr/Ca) ratios in otoliths is becoming a standard method to describe life history type and the chronology of migrations between freshwater and seawater habitats in teleosts (e.g. Kalish, 1990; Radtke et al., 1990; Secor, 1992; Rieman et al., 1994; Radtke, 1995; Limburg, 1995; Tzeng et al....
Numerical simulation of tsunami generation by pryoclastic flow at Aniakchak Volcano, Alaska
C. F. Waythomas, P. Watts
2003, Geophysical Research Letters (30)
Pyroclastic flows entering the sea are plausible mechanisms for tsunami generation at volcanic island arcs worldwide. We evaluate tsunami generation by pyroclastic flow using an example from Aniakchak volcano in Alaska where evidence for tsunami inundation coincident with a major, caldera-forming eruption of the volcano ca. 3.5 ka has been...
Guidelines for long-term monitoring protocols
Karen L. Oakley, Lisa P. Thomas, Steven G. Fancy
2003, Wildlife Society Bulletin (31) 1000-1003
Monitoring protocols are detailed study plans that explain how data are to be collected, managed, analyzed, and reported, and are a key component of quality assurance for natural resource monitoring programs. Protocols are necessary to ensure that changes detected by monitoring actually are occurring in nature and not simply a...
