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School of Natural Resources: Faculty Publications

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Articles 1201 - 1230 of 1586

Full-Text Articles in Physical Sciences and Mathematics

Selective Breeding For High Endurance Running Increases Hindlimb Symmetry, Theodore Garland Jr., Patricia W. Freeman Aug 2005

Selective Breeding For High Endurance Running Increases Hindlimb Symmetry, Theodore Garland Jr., Patricia W. Freeman

School of Natural Resources: Faculty Publications

Comparative studies provide correlational evidence of morphological adaptations for high locomotor performance, such as the classical indicators of cursoriality in mammals, long limbs and high metatarsal/femur ratios. More recently, enlarged femoral condyles have been suggested as an adaptation for high endurance running in the genus Homo. Asymmetry of locomotor appendages should adversely affect locomotor abilities, but this has not been studied in a rigorous evolutionary context. We used experimental evolution to test for morphological adaptations associated with high voluntary wheel running in selectively bred lines of mice. Surprisingly, the classical indicators of cursoriality had not evolved in concert with …


Evaluating The Simulation Of A Simple Hydrology Model Using Long-Term Soil Moisture Measurements In The Nebraska Sand Hills, V. Sridhar, Kenneth Hubbard, David A. Wedin Jul 2005

Evaluating The Simulation Of A Simple Hydrology Model Using Long-Term Soil Moisture Measurements In The Nebraska Sand Hills, V. Sridhar, Kenneth Hubbard, David A. Wedin

School of Natural Resources: Faculty Publications

In this paper, we investigate soil moisture, evapotranspiration and other major water balance components over six sites in the Sand Hills of Nebraska during a 6-year period (1998-2003) using a hydrological model. We simulate water budget components including root zone soil moisture and found that model predictions of soil moisture compare reasonably well with observations for these sites. In the precipitation-limited Sand Hills, a moderate change in precipitation pattern from year to year is found to have profound effects on the fast response components of the hydrological cycle. Despite the homogeneity in terms of soil (sandy) and vegetation (grass), both …


The July 2003 Dakota Hailswaths: Creation, Characteristics, And Possible Impacts, Matthew D. Parker, Ian Ratcliffe, Geoffrey M. Henebry Jul 2005

The July 2003 Dakota Hailswaths: Creation, Characteristics, And Possible Impacts, Matthew D. Parker, Ian Ratcliffe, Geoffrey M. Henebry

School of Natural Resources: Faculty Publications

The authors investigate the meteorology associated with two elongated swaths of crop damage produced by severe hailstorms that crossed North Dakota and South Dakota on 4 July and 20 July 2003. These hailswaths, which were observed in a Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) image time series, each persisted for more than a month and were associated with local temperature increases, presumably owing to the enhanced Bowen ratio over dry, crop-free ground. This paper documents the creation and evolution of the convective storms that produced the hailswaths, and then presents evidence that devegetated hailswaths may impact …


Seasonal And Interannual Varialbility In Evapotranspiration Of Native Tallgrass Prairie And Cultivated Wheat Ecosystems, By G.G. Burba, S.B. Verma, George G. Burba, Shashi B. Verma Jul 2005

Seasonal And Interannual Varialbility In Evapotranspiration Of Native Tallgrass Prairie And Cultivated Wheat Ecosystems, By G.G. Burba, S.B. Verma, George G. Burba, Shashi B. Verma

School of Natural Resources: Faculty Publications

No abstract provided.


Remote Monitoring Of Chlorophyll Concentrations In Productive Turbid Waters [Abstract], Anatoly A. Gitelson, Donald C. Rundquist Jun 2005

Remote Monitoring Of Chlorophyll Concentrations In Productive Turbid Waters [Abstract], Anatoly A. Gitelson, Donald C. Rundquist

School of Natural Resources: Faculty Publications

First sentence of abstract: For case 2 turbid productive waters, we describe an algorithm to retrieve chlorophyll-α (Chla) from reflectance spectra.


Remote Estimation Of Net Ecosystem Carbon Dioxide Exchange In Crops: Principles, Algorithm Calibration And Validation [Abstract], Anatoly A. Gitelson, Andrés Viña, Donald C. Rundquist, Shashi Verma Jun 2005

Remote Estimation Of Net Ecosystem Carbon Dioxide Exchange In Crops: Principles, Algorithm Calibration And Validation [Abstract], Anatoly A. Gitelson, Andrés Viña, Donald C. Rundquist, Shashi Verma

School of Natural Resources: Faculty Publications

First sentence of abstract: Accurate estimation of spatially distributed CO2 fluxes is of great importance for regional and global carbon balance studies.


Effect Of Bio-Optical Parameter Variability On The Remote Estimation Of Chlorophyll-A Concentration In Turbid Productive Waters: Experimental Results—Erratum, Giorgio Dall'olmo, Anatoly A. Gitelson Jun 2005

Effect Of Bio-Optical Parameter Variability On The Remote Estimation Of Chlorophyll-A Concentration In Turbid Productive Waters: Experimental Results—Erratum, Giorgio Dall'olmo, Anatoly A. Gitelson

School of Natural Resources: Faculty Publications

In the original publication [Dall’Olmo and Gitelson, Applied Optics (2005) 44: 412-422], certain information was presented inaccurately. These inaccuracies are corrected here.


Remote Estimation Of Crop Health [Abstract], Anatoly A. Gitelson, Andrés Viña, Donald C. Rundquist Jun 2005

Remote Estimation Of Crop Health [Abstract], Anatoly A. Gitelson, Andrés Viña, Donald C. Rundquist

School of Natural Resources: Faculty Publications

First sentence of abstract: In this paper we discuss developed techniques to remotely assess the fraction of photosynthetically active radiation absorbed by green vegetation [fAPAR-GREEN=fAPAR*(green LAI/total LAI)], fractional green vegetation cover (FGVC), green leaf area index (GLAI) green leaf biomass (GLB) and net ecosystem carbon dioxide exchange (NEE) in crops.


Apparent Soil Electrical Conductivity: Applications For Designing And Evaluating Field-Scale Experiments, C. K. Johnson, Kent M. Eskridge, D. L. Corwin Feb 2005

Apparent Soil Electrical Conductivity: Applications For Designing And Evaluating Field-Scale Experiments, C. K. Johnson, Kent M. Eskridge, D. L. Corwin

School of Natural Resources: Faculty Publications

On-farm field-scale research has become increasingly common with the advent of new technologies. While promoting a realistic systems perspective, field-scale experiments do not lend themselves to the traditional design concepts of replication and blocking. Previously, a farm-scale dryland experiment in northeastern Colorado was conducted to evaluate apparent electrical conductivity (ECa) classification (within-field blocking) as a basis for estimating plot-scale experimental error. Comparison of meansquare (MS) errors for several soil properties and surface residue mass measured at this site, with those from a nearby plot-scale experiment, revealed that ECa-classified within-field variance approximates plot-scale experimental error. In the …


Vertical Movement Of Water In A High Plains Aquifer Induced By A Pumping Well, Xunhong Chen, Yanfeng Yin, James W. Goeke, Robert F. Diffendal Jr. Feb 2005

Vertical Movement Of Water In A High Plains Aquifer Induced By A Pumping Well, Xunhong Chen, Yanfeng Yin, James W. Goeke, Robert F. Diffendal Jr.

School of Natural Resources: Faculty Publications

Field observation and numerical simulations were carried out to evaluate the hydraulic relationship between the shallow and deep aquifer of a High Plains Aquifer system, in which shallow and deep aquifers are separated by an aquitard. Pumping from the lower aquifer resulted in a small drawdown in the upper aquifer and a larger drawdown in the aquitard; pumping from the shallow aquifer caused a small drawdown in the aquitard and the deep aquifer. Analysis of pumping test data gives the values of the hydraulic conductivity of the aquitard and the deep aquifer. Long-term observation of groundwater levels in the shallow …


Effect Of Bio-Optical Parameter Variability On The Remote Estimation Of Chlorophyll-A Concentration In Turbid Productive Waters: Experimental Results, Giorgio Dall'olmo, Anatoly A. Gitelson Jan 2005

Effect Of Bio-Optical Parameter Variability On The Remote Estimation Of Chlorophyll-A Concentration In Turbid Productive Waters: Experimental Results, Giorgio Dall'olmo, Anatoly A. Gitelson

School of Natural Resources: Faculty Publications

The analytical development and underlying hypothesis of a three-band algorithm for estimating chlorophyll-a concentration ([Chla]) in turbid productive waters are presented. The sensitivity of the algorithm to the spectral location of the bands used is analyzed. A large set of experimental observations ([Chla] varied between 4 and 217 mg m-3 and turbidity between 2 and 78 nephelometric turbidity units) was used to calibrate and validate the algorithm. It was found that the variability of the chlorophyll-a fluorescence quantum yield and of the chlorophyll-a specific absorption coefficient can reduce considerably the accuracy of remote predictions of [Chla]. Instead of parameterizing …


Influence Of A Hailstreak On Boundary Layer Evolution, Zewdu T. Segele, David J. Stensrub, Ian C. Ratcliffe, Geoffrey M. Henebry Jan 2005

Influence Of A Hailstreak On Boundary Layer Evolution, Zewdu T. Segele, David J. Stensrub, Ian C. Ratcliffe, Geoffrey M. Henebry

School of Natural Resources: Faculty Publications

Severe thunderstorms developed on 20 June 1997 and produced heavy precipitation, damaging winds, and large hail over two swaths in southeastern South Dakota. Calculations of fractional vegetation coverage (scaled from 0 to 1) based upon composite satellite data indicate that, within the hailstreak region, vegetation coverage decreased from 0.50 to near 0.25 owing to the damaging effects of hail on the growing vegetation. The northern edge of the larger hailstreak was located a few kilometers south of Chamberlain, South Dakota, a National Weather Service surface observation site. Hourly observations from Chamberlain and several nearby surface sites in South Dakota are …


Quality Control Of Pre-1948 Cooperative Observer Network Data, Kenneth E. Kunkel, David R. Easterling, Kenneth Hubbard, Kelly Redmond, Karen Andsager, Michael C. Kruk, Michael L. Spinar Jan 2005

Quality Control Of Pre-1948 Cooperative Observer Network Data, Kenneth E. Kunkel, David R. Easterling, Kenneth Hubbard, Kelly Redmond, Karen Andsager, Michael C. Kruk, Michael L. Spinar

School of Natural Resources: Faculty Publications

A recent comprehensive effort to digitize U.S. daily temperature and precipitation data observed prior to 1948 has resulted in a major enhancement in the computer database of the records of the National Weather Service’s cooperative observer network. Previous digitization efforts had been selective, concentrating on state or regional areas. Special quality control procedures were applied to these data to enhance their value for climatological analysis. The procedures involved a two-step process. In the first step, each individual temperature and precipitation data value was evaluated against a set of objective screening criteria to flag outliers. These criteria included extreme limits and …


Effects Of Spring Supplementary Feeding On Population Density And Breeding Success Of Released Pheasants Phasianus Colchicus In Britain, Roger A. H. Draycott, Maureen I. A. Woodburn, John P. Carroll, Rufus B. Sage Jan 2005

Effects Of Spring Supplementary Feeding On Population Density And Breeding Success Of Released Pheasants Phasianus Colchicus In Britain, Roger A. H. Draycott, Maureen I. A. Woodburn, John P. Carroll, Rufus B. Sage

School of Natural Resources: Faculty Publications

The release of hand-reared ring-necked pheasants Phasianus colchicus in summer is a common practice in Britain to increase the number of birds available to hunters in winter. The breeding success of the birds which survive the shooting season is poor. Traditionally, birds are provided with supplementary wheat grain from release until the end of the shooting season (1 February) to maintain body condition and to help hold birds in areas for hunting. During 1997- 2000 we assessed the effect of continuing supplementary feeding into spring on pheasant density and breeding success on seven private shooting estates. On each estate we …


Social Science To Improve Fuels Management: A Synthesis Of Research Relevant To Communicating With Homeowners About Fuels Management, Martha C. Monroe, Lisa Pennisi, Sarah Mccaffrey, Dennis Mileti Jan 2005

Social Science To Improve Fuels Management: A Synthesis Of Research Relevant To Communicating With Homeowners About Fuels Management, Martha C. Monroe, Lisa Pennisi, Sarah Mccaffrey, Dennis Mileti

School of Natural Resources: Faculty Publications

No abstract provided.


Discrete State-Space Approximation Of The Continuous Kalinin-Milyukov-Nash Cascade Of Noninteger Storage Elements, Jozsef Szilagyi Jan 2005

Discrete State-Space Approximation Of The Continuous Kalinin-Milyukov-Nash Cascade Of Noninteger Storage Elements, Jozsef Szilagyi

School of Natural Resources: Faculty Publications

No abstract provided.


Flow Routing With Unknown Rating Curves Using A State-Space Reservoir-Cascade-Type Formulation, Jozsef Szilagyi, Gabor Balint, Balazs Gauzer, Peter Bartha Jan 2005

Flow Routing With Unknown Rating Curves Using A State-Space Reservoir-Cascade-Type Formulation, Jozsef Szilagyi, Gabor Balint, Balazs Gauzer, Peter Bartha

School of Natural Resources: Faculty Publications

No abstract provided.


Effects Of Climate And Landcover Change On Stream Discharge In The Ozark Highlands, Usa, Q. Steven Hu, Gary D. Willson, Xi Chen, Adnan Adnan Jan 2005

Effects Of Climate And Landcover Change On Stream Discharge In The Ozark Highlands, Usa, Q. Steven Hu, Gary D. Willson, Xi Chen, Adnan Adnan

School of Natural Resources: Faculty Publications

Stream discharge of a watershed is affected and altered by climate and landcover changes. These effects vary depending on the magnitude and interaction of the changes, and need to be understood so that local water resource availability can be evaluated and socioeconomic development within a watershed be pursued and managed in a way sustainable with the local water resources. In this study, the landcover and climate change effects on stream discharge from the Jacks Fork River basin in the Ozark Highlands of the south-central United States were examined in three phases: site observation and data collection, model calibration and simulation, …


Multi-Platform Comparisons Of Modis And Avhrr Normalized Difference Vegetation Index Data, Kevin P. Gallo, Lei Ji, Brad Reed, Jeffrey Eidenshink, John Dwyer Jan 2005

Multi-Platform Comparisons Of Modis And Avhrr Normalized Difference Vegetation Index Data, Kevin P. Gallo, Lei Ji, Brad Reed, Jeffrey Eidenshink, John Dwyer

School of Natural Resources: Faculty Publications

The relationship between AVHRR-derived normalized difference vegetation index (NDVI) values and those of future sensors is critical to continued long-term monitoring of land surface properties. The follow-on operational sensor to the AVHRR, the Visible/Infrared Imager/ Radiometer Suite (VIIRS), will be very similar to the NASA Earth Observing System’s Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. NDVI data derived from visible and near-infrared data acquired by the MODIS (Terra and Aqua platforms) and AVHRR (NOAA-16 and NOAA-17) sensors were compared over the same time periods and a variety of land cover classes within the conterminous United States. The results indicate that the …


An Artificial-Neural-Network-Based, Constrained Ca Model For Simulating Urban Growth, Qingfeng Guan, Liming Wang, Keith C. Clarke Jan 2005

An Artificial-Neural-Network-Based, Constrained Ca Model For Simulating Urban Growth, Qingfeng Guan, Liming Wang, Keith C. Clarke

School of Natural Resources: Faculty Publications

Insufficient research has been done on integrating artificial-neural-network-based cellular automata (CA) models and constrained CA models, even though both types have been studied for several years. In this paper, a constrained CA model based on an artificial neural network (ANN) was developed to simulate and forecast urban growth. Neural networks can learn from available urban land-use geospatial data and thus deal with redundancy, inaccuracy, and noise during the CA parameter calibration. In the ANN -Urban-CA model we used, a two-layer Back-Propagation (BP) neural network has been integrated into a CA model to seek suitable parameter values that match the historical …


Development Of A Quality-Assessed Agrichemical Database For Monitoring Anthropogenic Impacts On Ground-Water Quality, Mary Exner Spalding, Roy F. Spalding, Dorothy M. Harrell Jan 2005

Development Of A Quality-Assessed Agrichemical Database For Monitoring Anthropogenic Impacts On Ground-Water Quality, Mary Exner Spalding, Roy F. Spalding, Dorothy M. Harrell

School of Natural Resources: Faculty Publications

The Quality-Assessed Agrichemical Contaminant Database for Nebraska Ground Water is a unique repository of nitrate and pesticide data collected by federal, state, and local agencies. Each contaminant concentration in the database has been evaluated based upon well-defined criteria that address completeness of the well-attribute data, analytical method and field and laboratory quality control practices and assigned to one of five quality levels. The quality assessment level always accompanies the contaminant concentration so that the end-user knows the quality assurance effort expended in the acquisition of the data, can select comparable data, and choose data whose quality assurance effort is commensurate …


Some Concerns When Using Data From The Cooperative Weather Station Networks: A Nebraska Case Study, Hong Wu, Kenneth G. Hubbard, Jinsheng You Jan 2005

Some Concerns When Using Data From The Cooperative Weather Station Networks: A Nebraska Case Study, Hong Wu, Kenneth G. Hubbard, Jinsheng You

School of Natural Resources: Faculty Publications

In this study, daily temperature and precipitation amounts that are observed by the Cooperative Observer Program (COOP) were compared among geographically close stations. Hourly observations from nearby Automatic Weather Data Network (AWDN) stations were utilized to resolve the discrepancies between the observations during the same period. The statistics of maximum differences in temperature and precipitation between COOP stations were summarized. In addition, the quantitative measures of the deviations between COOP and AWDN stations were expressed by root-mean-square error, mean absolute error, and an index of agreement. The results indicated that significant discrepancies exist among the daily observations between some paired …


Optimizing Allocation Of Monitoring Effort Under Economic And Observational Constraints, Scott A. Field, Andrew J. Tyre, Hugh P. Possingham Jan 2005

Optimizing Allocation Of Monitoring Effort Under Economic And Observational Constraints, Scott A. Field, Andrew J. Tyre, Hugh P. Possingham

School of Natural Resources: Faculty Publications

Efforts to design monitoring regimes capable of detecting population trends can be thwarted by observational and economic constraints inherent to most biological surveys. Ensuring that limited resources are allocated efficiently requires evaluation of statistical power for alternative survey designs. We simulated the process of data collection on a landscape, where we initiated declines over 3 sample periods in species of varying prevalence and detectability. Changing occupancy levels were estimated using a technique that accounted for effects of false-negative errors on survey data. Declines were identified within a frequentist statistical framework, but the significance level was set at an optimal level …


Steroid Hormone Levels Are Related To Choice Of Colony Size In Cliff Swallows, Charles R. Brown, Mary Bomberger Brown, Samrrah A. Raouf, Linda C. Smith, John C. Wingfield Jan 2005

Steroid Hormone Levels Are Related To Choice Of Colony Size In Cliff Swallows, Charles R. Brown, Mary Bomberger Brown, Samrrah A. Raouf, Linda C. Smith, John C. Wingfield

School of Natural Resources: Faculty Publications

One hypothesis to explain the extensive variation in colony size seen in most
taxa is that individuals sort themselves among groups based on phenotypic characteristics
that correlate with their performance in groups of different sizes. We investigated how
baseline levels of the steroid hormones, corticosterone and testosterone, were associated
with choice of colony size and the likelihood of moving to a different site in later years
in colonially nesting Cliff Swallows (Petrochelidon pyrrhonota) in southwestern Nebraska,
USA, in 2000–2004. We sampled hormone levels of birds caught at colonies and, using
mark–recapture, monitored their movement and choice of colony size …


Objective Threshold Determination For Nighttime Eddy Flux Filtering, Lianhong Gu, Eva M. Falge, Tom Boden, Dennis D. Baldocchi, T.A. Black, Scott R. Saleska, Tanja Suni, Shashi Verma, Timo Vesala, Steve C. Wofsy, Liukang Xu Jan 2005

Objective Threshold Determination For Nighttime Eddy Flux Filtering, Lianhong Gu, Eva M. Falge, Tom Boden, Dennis D. Baldocchi, T.A. Black, Scott R. Saleska, Tanja Suni, Shashi Verma, Timo Vesala, Steve C. Wofsy, Liukang Xu

School of Natural Resources: Faculty Publications

We recommend an automated statistical method (Moving Point Test, or MPT) to determine the friction velocity (u*) thresholds in nighttime eddy flux filtering. Our intention is to make the determination of the u* thresholds objective and reproducible and to keep flux treatment consistent over time and across sites. In developing the MPT method, we recognize that both ecosystem respiration and u* exhibit diurnal and seasonal cycles and there are potential correlative changes between them, which must be removed before u* can be used as a filter criterion. MPTuses an iterative approach to simultaneously determine a valid temperature response function, which …


The Evolution Of A Warm Season Severe Eastern Kentucky Flash Flood, C. Henry, R. Mahmood, C. Smallcomb, M. Mclane, D. Champlin Jan 2005

The Evolution Of A Warm Season Severe Eastern Kentucky Flash Flood, C. Henry, R. Mahmood, C. Smallcomb, M. Mclane, D. Champlin

School of Natural Resources: Faculty Publications

No abstract provided.


An Assessment Of Key Aspects Of Warm And Cool Season Severe Flash Flooding In The Southern Appalachians, W. M. Baldwin, R. Mahmood Jan 2005

An Assessment Of Key Aspects Of Warm And Cool Season Severe Flash Flooding In The Southern Appalachians, W. M. Baldwin, R. Mahmood

School of Natural Resources: Faculty Publications

No abstract provided.


Pervasiveness Of Phytoliths In Prehistoric Southwestern Diet And Implications For Regional And Temporal Trends For Dental Microwear, Karl J. Reinhard, Dennis R. Danielson Jan 2005

Pervasiveness Of Phytoliths In Prehistoric Southwestern Diet And Implications For Regional And Temporal Trends For Dental Microwear, Karl J. Reinhard, Dennis R. Danielson

School of Natural Resources: Faculty Publications

Our previous analysis of phytolith content of coprolites showed that calcium oxalate phytoliths from desert food plants caused dental microwear among prehistoric Texas hunter-gatherers. We demonstrated that phytoliths from desert succulents were ubiquitous and abundant in hunter-gatherer coprolites. We found that calcium oxalate phytoliths were harder than human dental enamel. We concluded that phytoliths from desert succulent plants caused dental microwear and hypothesized that such dental microwear would be common in other desert hunter-gatherer and horticultural peoples. Presented here are further analyses of phytoliths from coprolites. Two additional hunter-gatherer sites and three Ancestral Pueblo (Anasazi) horticultural sites are included in …


Atmospheric Circulation And Cyclone Frequency Variations Linked To The Primary Modes Of Greenland Snow Accumulation, Jeffrey C. Rogers, Deborah J. Bathke, Ellen Mosley-Thompson, Sheng-Hung Wang Dec 2004

Atmospheric Circulation And Cyclone Frequency Variations Linked To The Primary Modes Of Greenland Snow Accumulation, Jeffrey C. Rogers, Deborah J. Bathke, Ellen Mosley-Thompson, Sheng-Hung Wang

School of Natural Resources: Faculty Publications

Data from 34 Greenland firn cores, extending from 1982 to 1996, are used to identify spatial accumulation variability patterns and their associated atmospheric circulation and cyclone frequencies. The first principal component, representing west-central Greenland accumulation, is correlated to NAO variability, having increased southwesterly (northeasterly) flow over that area during high (low) accumulation winters. The flow is linked to a relative increase in cyclone activity on the west central region of the ice sheet during high accumulation periods. The second principal component represents accumulation over southeastern Greenland where strong westerly flow leads to high accumulation and an increase in lee cyclones …


On The Uscrn Temperature System, Kenneth Hubbard, X. Lin, C.B. Baker Sep 2004

On The Uscrn Temperature System, Kenneth Hubbard, X. Lin, C.B. Baker

School of Natural Resources: Faculty Publications

In 2004 a new aspirated surface air temperature system was officially deployed nationally in the U.S. Climate Reference Network (USCRN) commissioned by the National Oceanic and Atmospheric Admin- istration. The primary goal of the USCRN is to provide future long-term and high-quality homogeneous observations of surface air temperature and precipitation that can be coupled to past long-term observations for the detection and attribution of present and future climate change. In this paper two precision air temperature systems are included for evaluating the new USCRN air temperature system based on a 1-yr side-by-side field comparison. The measurement errors of the USCRN …