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Articles 31 - 60 of 1544

Full-Text Articles in Physical Sciences and Mathematics

Modeling Spatial And Temporal Variation In Natural Background Specific Conductivity, John Olson, Susan M. Cormier Mar 2019

Modeling Spatial And Temporal Variation In Natural Background Specific Conductivity, John Olson, Susan M. Cormier

John Olson

ABSTRACT: Understanding how background levels of dissolved minerals vary in streams temporally and spatially is needed to assess salinization of fresh water, establish reasonable thresholds and restoration goals, and determine vulnerability to extreme climate events like drought. We developed a random forest model that predicts natural background specific conductivity (SC), a measure of total dissolved ions, for all stream segments in the contiguous United States at monthly time steps between the years 2001 to 2015. Models were trained using 11 796 observations made at 1785 minimally impaired stream segments and validated with observations from an additional 92 segments. Static predictors …


Effectiveness Of Four Water-Bearing Zones Of The Glacierized Basin In Meltwater Runoff Modeling, Umesh K. Haritashya Mar 2019

Effectiveness Of Four Water-Bearing Zones Of The Glacierized Basin In Meltwater Runoff Modeling, Umesh K. Haritashya

Umesh K. Haritashya

Meltwater runoff modeling from glacierized basins needs several input data, including total meltwater contributing area. This study utilizes optical remote sensing data to assess glacierized basins in the central Himalayas where snow and glaciers contribute substantially to the water resources. Result shows that there are four main water-bearing zones in the basin: (a) dry snow, (b) wet snow, (c) exposed glacial ice, and (d) debris-covered glacial ice, and it is possible to differentiate and map these zones and their spatio-temporal variations from satellite sensor data. These zones can then be incorporated in meltwater runoff modeling as separate entities because they …


Climate Change And The Global Pattern Of Moraine-Dammed Glacial Lake Outburst Floods, Stephan Harrison, Jeffrey S. Kargel, Christian Huggel, John Reynolds, Dan H. Shugar, Richard A. Betts, Neil Glasser, Umesh K. Haritashya, Jan Klimeš, Liam Reinhardt, Yvonne Schaub, Andy Wiltshire, Dhananjay Regmi, Vít Vilímek Mar 2019

Climate Change And The Global Pattern Of Moraine-Dammed Glacial Lake Outburst Floods, Stephan Harrison, Jeffrey S. Kargel, Christian Huggel, John Reynolds, Dan H. Shugar, Richard A. Betts, Neil Glasser, Umesh K. Haritashya, Jan Klimeš, Liam Reinhardt, Yvonne Schaub, Andy Wiltshire, Dhananjay Regmi, Vít Vilímek

Umesh K. Haritashya

Despite recent research identifying a clear anthropogenic impact on glacier recession, the effect of recent climate change on glacier-related hazards is at present unclear. Here we present the first global spatio-temporal assessment of glacial lake outburst floods (GLOFs) focusing explicitly on lake drainage following moraine dam failure. These floods occur as mountain glaciers recede and downwaste. GLOFs can have an enormous impact on downstream communities and infrastructure. Our assessment of GLOFs associated with the rapid drainage of moraine-dammed lakes provides insights into the historical trends of GLOFs and their distributions under current and future global climate change. We observe a …


Evolution And Controls Of Large Glacial Lakes In The Nepal Himalaya, Umesh K. Haritashya, Jeffrey S. Kargel, Dan H. Shugar, Gregory J. Leonard, Katherine Strattman, C. Scott Watson, David Shean, Stephan Harrison, Kyle T. Mandli, Dhananjay Regmi Mar 2019

Evolution And Controls Of Large Glacial Lakes In The Nepal Himalaya, Umesh K. Haritashya, Jeffrey S. Kargel, Dan H. Shugar, Gregory J. Leonard, Katherine Strattman, C. Scott Watson, David Shean, Stephan Harrison, Kyle T. Mandli, Dhananjay Regmi

Umesh K. Haritashya

Glacier recession driven by climate change produces glacial lakes, some of which are hazardous. Our study assesses the evolution of three of the most hazardous moraine-dammed proglacial lakes in the Nepal Himalaya—Imja, Lower Barun, and Thulagi. Imja Lake (up to 150 m deep; 78.4 x 106 m3 volume; surveyed in October 2014) and Lower Barun Lake (205 m maximum observed depth; 112.3 x 106 m3 volume; surveyed in October 2015) are much deeper than previously measured, and their readily drainable volumes are slowly growing. Their surface areas have been increasing at an accelerating pace from a …


Supplemental Data For 'Evolution And Controls Of Large Glacial Lakes In The Nepal Himalaya', Umesh K. Haritashya, Jeffrey S. Kargel, Dan H. Shugar, Gregory J. Leonard, Katherine Strattman, C. Scott Watson, David Shean, Stephan Harrison, Kyle T. Mandli, Dhananjay Regmi Mar 2019

Supplemental Data For 'Evolution And Controls Of Large Glacial Lakes In The Nepal Himalaya', Umesh K. Haritashya, Jeffrey S. Kargel, Dan H. Shugar, Gregory J. Leonard, Katherine Strattman, C. Scott Watson, David Shean, Stephan Harrison, Kyle T. Mandli, Dhananjay Regmi

Umesh K. Haritashya

Supplementary data for the article "Evolution and Controls of Large Glacial Lakes in the Nepal Himalaya"


Scott Marshall With Student.Jpg, Scott Marshall Dec 2018

Scott Marshall With Student.Jpg, Scott Marshall

Dr. Scott Marshall

Dr. Scott Marshall works with an Appalachian State University student on an undergraduate research project.


Predicting Combined Effects Of Land Use And Climate Change On River And Stream Salinity, John Olson Dec 2018

Predicting Combined Effects Of Land Use And Climate Change On River And Stream Salinity, John Olson

John Olson

Agricultural, industrial and urban development have all contributed to increased salinity in streams and rivers, but the likely effects of future development and climate change are unknown. I developed two empirical models
to estimate how these combined effects might affect salinity by the end of this century (measured as electrical conductivity, EC). The first model predicts natural background from static (e.g. geology and soils) and dynamic
(i.e. climate and vegetation) environmental factors and explained 78% of the variation in EC. I then compared the estimated background EC with current measurements at 2001 sites chosen probabilistically from all conterminous USA streams. …


Belowground Rhizomes In Paleosols: The Hidden Half Of An Early Devonian Vascular Plant, Jinzhuang Xue, Zhenzhen Deng, Pu Huang, Kangjun Huang, Michael J. Benton, Ying Cui Oct 2018

Belowground Rhizomes In Paleosols: The Hidden Half Of An Early Devonian Vascular Plant, Jinzhuang Xue, Zhenzhen Deng, Pu Huang, Kangjun Huang, Michael J. Benton, Ying Cui

Ying Cui

The colonization of terrestrial environments by rooted vascular plants had far-reaching impacts on the Earth system. However, the belowground structures of early vascular plants are rarely documented, and thus the plant−soil interactions in early terrestrial ecosystems are poorly understood. Here we report the earliest rooted paleosols (fossil soils) in Asia from Early Devonian deposits of Yunnan, China. Plant traces are extensive within the soil and occur as complex network-like structures, which are interpreted as representing long-lived, belowground rhizomes of the basal lycopsid Drepanophycus. The rhizomes produced large clones and helped the plant survive frequent sediment burial in well-drained soils …


Input Uncertainty On Watershed Modeling: Evaluation Of Precipitation And Air Temperature Data By Latent Variables Using Swat, Ruoyu Wang Oct 2018

Input Uncertainty On Watershed Modeling: Evaluation Of Precipitation And Air Temperature Data By Latent Variables Using Swat, Ruoyu Wang

Ruoyu Wang

Latent variables (i.e., normally distributed random noise) provide valuable information regarding model input uncertainty. Watershed processes have been explored with sophisticated simulation models in the past few decades and researchers have found that incorporating the uncertainty attributed to forcing inputs, model parameters, and measured data, can help improve simulation results, however, not in all cases. Latent variable use requires careful consideration to determine if results are better or worse. In this study, latent variables were implemented to both precipitation and air temperature data to investigate the influence on model predictions and associated predictive uncertainty by using the Soil and Water …


Edible Forest Gardens- Perennial Ag Fo Eco Regeneration .Pdf, Lisa Depiano Sep 2018

Edible Forest Gardens- Perennial Ag Fo Eco Regeneration .Pdf, Lisa Depiano

Lisa DePiano

A semester long course in Edible Forest Gardening and Perennial Agriculture


Magnetic Properties Of A Sediment Core From Andvord Drift, Emily Youcha, Stefanie A. Brachfeld Aug 2018

Magnetic Properties Of A Sediment Core From Andvord Drift, Emily Youcha, Stefanie A. Brachfeld

Stefanie Brachfeld

No abstract provided.


Magnetic Granulometry Of Igneous And Metasedimentary Rocks From Northern Graham Land, Antarctic Peninsula, Stefanie A. Brachfeld, Anne Grunow, Emily Youcha Aug 2018

Magnetic Granulometry Of Igneous And Metasedimentary Rocks From Northern Graham Land, Antarctic Peninsula, Stefanie A. Brachfeld, Anne Grunow, Emily Youcha

Stefanie Brachfeld

No abstract provided.


Rock-Magnetic Analysis Of Sediments From Andvord Bay, Stefanie A. Brachfeld Aug 2018

Rock-Magnetic Analysis Of Sediments From Andvord Bay, Stefanie A. Brachfeld

Stefanie Brachfeld

No abstract provided.


Multicomponent Cubic Oxide Exsolution In Synthetic Basalts: Temperature Dependence And Implications For Magnetic Properties, Julie A. Bowles, Lisa Tatsumi-Petrochilos, Julie E. Hammer, Stefanie A. Brachfeld Aug 2018

Multicomponent Cubic Oxide Exsolution In Synthetic Basalts: Temperature Dependence And Implications For Magnetic Properties, Julie A. Bowles, Lisa Tatsumi-Petrochilos, Julie E. Hammer, Stefanie A. Brachfeld

Stefanie Brachfeld

Although the compositional unmixing of cubic-structured iron oxides has profound effects on the magnetic properties of rocks that contain them, a basic understanding of the kinetics and thermodynamics of this process has not been achieved in experimental studies due to sluggish reaction rates in binary oxide phases. Exploiting the fact that many natural Fe-oxides contain multiple additional cations, including Ti, Mg and Al, we perform novel “forward” laboratory experiments in which cubic-cubic phase exsolution proceeds from initially homogeneous multicomponent oxides. A variety of Fe-Ti-Mg-Al cubic iron oxides were nucleated and grown in synthetic, multicomponent basalt under different ƒO2 environments, and …


Magnetic And Petrologic Characterization Of Synthetic Martian Basalts And Implications For The Surface Magnetization Of Mars, Julie A. Bowles, Julie E. Hammer, Stefanie A. Brachfeld Aug 2018

Magnetic And Petrologic Characterization Of Synthetic Martian Basalts And Implications For The Surface Magnetization Of Mars, Julie A. Bowles, Julie E. Hammer, Stefanie A. Brachfeld

Stefanie Brachfeld

A suite of synthetic Martian basalts is generated with the objective of providing fundamental material properties data for use in modeling and interpretation of mission data. We systematically evaluate the effects of major element composition, oxygen fugacity (ƒO2), and cooling rate on phase chemistry and magnetic mineralogy, grain size, and intensity of remanent magnetization. The range of experimental compositions and ƒO2 are chosen to bracket the range expected in the Martian crust; our results should therefore span the range of possible mineralogies, textures, and magnetic properties in rapidly cooled Mars crustal materials. Two starting compositions are used for …


Contribution Of Multidomain Titanomagnetite To The Intensity And Stability Of Mars Crustal Magnetic Anomalies, Stefanie A. Brachfeld, David Cuomo, Lisa Tatsumi-Petrochilos, Julie A. Bowles, Deepa Shah, Julie E. Hammer Aug 2018

Contribution Of Multidomain Titanomagnetite To The Intensity And Stability Of Mars Crustal Magnetic Anomalies, Stefanie A. Brachfeld, David Cuomo, Lisa Tatsumi-Petrochilos, Julie A. Bowles, Deepa Shah, Julie E. Hammer

Stefanie Brachfeld

Two basalts with compositions relevant to the crusts of Mars and Earth were synthesized at igneous temperatures and held at 650°C for 21 to 257 days under quartz-fayalite-magnetite ƒO2 buffer conditions. The run products are germane to slowly cooled igneous intrusions, which might be a significant volumetric fraction of the Martian crust and carriers of magnetic anomalies in the Southern Highlands. Both basalts acquired intense thermoremanent magnetizations and intense but easily demagnetized anhysteretic remanent magnetizations carried by homogeneous multidomain titanomagnetite. Hypothetical intrusions on Mars composed of these materials would be capable of acquiring intense remanences sufficient to generate the …


Tiered Approaches In Analyzing Rice Field Pesticide Fate And Transport For Ecological Risk Assessment, Ruoyu Wang Jul 2018

Tiered Approaches In Analyzing Rice Field Pesticide Fate And Transport For Ecological Risk Assessment, Ruoyu Wang

Ruoyu Wang

No abstract provided.


Early Miocene Antarctic Glacial History: New Insights From Heavy Mineral Analysis From Andrill And–2a Drill Core Sediments, Francesco Iacoviello, Giovanna Giorgetti, Isabella Turbanti Memmi, Sandra Passchier Jul 2018

Early Miocene Antarctic Glacial History: New Insights From Heavy Mineral Analysis From Andrill And–2a Drill Core Sediments, Francesco Iacoviello, Giovanna Giorgetti, Isabella Turbanti Memmi, Sandra Passchier

Sandra Passchier

The present study deals with heavy mineral analysis of late Early Miocene marine sediments recovered in the McMurdo Sound region (Ross Sea, Antarctica) during the ANDRILL— SMS Project in 2007. The main objective is to investigate how heavy mineral assemblages reflect different source rocks and hence different provenance areas. These data contribute to a better understanding of East Antarctica ice dynamics in the Ross Sea sector during the Early Miocene (17.6–20.2 Ma), a time of long-term global warming and sea level rise. The AND-2A drill core recovered several stratigraphic intervals that span from Early Miocene to Pleistocene and it collected …


Orbitally Induced Oscillations In The East Antarctic Ice Sheet At The Oligocene/Miocene Boundary, Tim R. Naish, Ken J. Woolfe, Peter J. Barrett, Gary S. Wilson, Cliff Atkins, Steven M. Bohaty, Christian J. Bücker, Michele Claps, Fred J. Davey, Gavin B. Dunbar, Alistair G. Dunn, Christopher R. Fielding, Fabio Florindo, Michael J. Hannah, David M. Harwood, Stuart A. Henrys, Lawrence A. Krissek, Mark Lavelle, Jaap Van Der Meer, William C. Mcintosh, Frank Niessen, Sandra Passchier, Ross D. Powell, Andrew P. Roberts, Leonardo Sagnotti, Reed P. Scherer, C. Percy Strong, Franco Talarico, Kenneth L. Verosub, Giuliana Villa, David K. Watkins, Peter-N. Webb, Thomas Wonik Jul 2018

Orbitally Induced Oscillations In The East Antarctic Ice Sheet At The Oligocene/Miocene Boundary, Tim R. Naish, Ken J. Woolfe, Peter J. Barrett, Gary S. Wilson, Cliff Atkins, Steven M. Bohaty, Christian J. Bücker, Michele Claps, Fred J. Davey, Gavin B. Dunbar, Alistair G. Dunn, Christopher R. Fielding, Fabio Florindo, Michael J. Hannah, David M. Harwood, Stuart A. Henrys, Lawrence A. Krissek, Mark Lavelle, Jaap Van Der Meer, William C. Mcintosh, Frank Niessen, Sandra Passchier, Ross D. Powell, Andrew P. Roberts, Leonardo Sagnotti, Reed P. Scherer, C. Percy Strong, Franco Talarico, Kenneth L. Verosub, Giuliana Villa, David K. Watkins, Peter-N. Webb, Thomas Wonik

Sandra Passchier

Between 34 and 15 million years (Myr) ago, when planetary temperatures were 3-4°C warmer than at present and atmospheric CO2 concentrations were twice as high as today, the Antarctic ice sheets may have been unstable. Oxygen isotope records from deep-sea sediment cores suggest that during this time fluctuations in global temperatures and high-latitude continental ice volumes were influenced by orbital cycles. But it has hitherto not been possible to calibrate the inferred changes in ice volume with direct evidence for oscillations of the Antarctic ice sheets. Here we present sediment data from shallow marine cores in the western Ross …


The Meaning Of Yom In Genesis 1:5, David C. Taylor Jr Jul 2018

The Meaning Of Yom In Genesis 1:5, David C. Taylor Jr

David C Taylor Jr

No abstract provided.


Multivariate Spectral Analysis Of Crism Data To Characterize The Composition Of Mawrth Vallis, Melissa Luna Mar 2018

Multivariate Spectral Analysis Of Crism Data To Characterize The Composition Of Mawrth Vallis, Melissa Luna

Melissa Luna

No abstract provided.


Discovery And Geology Of The Guinness World Record Lake Copper, Lake Superior, Michigan, Theodore J. Bornhorst, Robert Barron Jan 2018

Discovery And Geology Of The Guinness World Record Lake Copper, Lake Superior, Michigan, Theodore J. Bornhorst, Robert Barron

Theodore J. Bornhorst

No abstract provided.


Examining The Use Of Amazon’S Mechanical Turk For Edge Extraction Of The Occlusal Surface Of Fossilized Bovid Teeth, George K. Thiruvathukal, Gregory J. Matthews, Maxwell P. Luetkemeier, Juliet K. Brophy Jan 2018

Examining The Use Of Amazon’S Mechanical Turk For Edge Extraction Of The Occlusal Surface Of Fossilized Bovid Teeth, George K. Thiruvathukal, Gregory J. Matthews, Maxwell P. Luetkemeier, Juliet K. Brophy

George K. Thiruvathukal

In order to reconstruct environments associated with Plio-Pleistocene hominins in southern Africa, researchers frequently rely upon the animals associated with the hominins, in particular, animals in the Family Bovidae. Bovids in southern Africa are typically identified by their teeth. However, identifying the taxon of a bovid tooth is challenging due to various biasing factors. Furthermore, inaccurate identification of fossil bovids can have significant consequences on the reconstructed paleoenvironment. Recent research on the classification of bovid fossil teeth has relied on using elliptical Fourier analysis to summarize the shape of the outline of the occlusal surface of the tooth and the …


Deformation Of Fine-Grained Quartz Aggregates By Mixed Diffusion And Dislocation Creep, Junichi Fukuda, Caleb Holyoke, Andreas Kronenberg Dec 2017

Deformation Of Fine-Grained Quartz Aggregates By Mixed Diffusion And Dislocation Creep, Junichi Fukuda, Caleb Holyoke, Andreas Kronenberg

Caleb Holyoke

No abstract provided.


William Anderson.Jpg Dec 2017

William Anderson.Jpg

Dr. William P. Anderson Jr.

No abstract provided.


Reference Data Set Of Volcanic Ash Physicochemical And Optical Properties, A. Vogel, S. Diplas, A. J. Durant, A. S. Azar, M. F. Sunding, William I. Rose, A. Sytchkova, C. Bonadonna, K. Krüger, A. Stohl Oct 2017

Reference Data Set Of Volcanic Ash Physicochemical And Optical Properties, A. Vogel, S. Diplas, A. J. Durant, A. S. Azar, M. F. Sunding, William I. Rose, A. Sytchkova, C. Bonadonna, K. Krüger, A. Stohl

William I. Rose

Uncertainty in the physicochemical and optical properties of volcanic ash particles creates errors in the detection and modeling of volcanic ash clouds and in quantification of their potential impacts. In this study, we provide a data set that describes the physicochemical and optical properties of a representative selection of volcanic ash samples from nine different volcanic eruptions covering a wide range of silica contents (50–80 wt % SiO2). We measured and calculated parameters describing the physical (size distribution, complex shape, and dense-rock equivalent mass density), chemical (bulk and surface composition), and optical (complex refractive index from ultraviolet to near-infrared wavelengths) …


Notes On Eryx, Omega, And Ata, Victor Fet Sep 2017

Notes On Eryx, Omega, And Ata, Victor Fet

Victor Fet

Observations on several Nabokov’s works (Pale Fire, Lolita) where geographic or zoological names provide sources for puns and hidden parallels.


Nitrogen Fertilizer Rate Effects On Soil Organic Carbon In Iowa Continuous Corn And Corn-Soybean Systems, Hanna J. Poffenbarger, Daniel W. Barker, Matthew J. Helmers, Fernando E. Miguez, John E. Sawyer, Johan Six, Michael J. Castellano Aug 2017

Nitrogen Fertilizer Rate Effects On Soil Organic Carbon In Iowa Continuous Corn And Corn-Soybean Systems, Hanna J. Poffenbarger, Daniel W. Barker, Matthew J. Helmers, Fernando E. Miguez, John E. Sawyer, Johan Six, Michael J. Castellano

John E. Sawyer

Nitrogen fertilizer rate is a key factor affecting soil organic C (SOC) in corn-based cropping systems. The objective of this study was to determine the change in SOC in response to long-term N rates for continuous corn and corn-soybean cropping systems at two sites in Iowa. Soil samples were collected to a depth of 15 cm in 1999 and again in 2014 after 15 years of corn N rate treatments ranging from 0 to 269 kg ha-1. The soil samples were analyzed for total C and N concentrations. For continuous corn at both sites, the average annual change …


New Genera And Species Of Fossil Marine Amioid Fishes (Actinopterygii, Holostei) From The Late Cretaceous Agoult Locality In Southeastern Morocco, Mark V. H. Wilson, Alison M. Murray, Terry C. Grande Jul 2017

New Genera And Species Of Fossil Marine Amioid Fishes (Actinopterygii, Holostei) From The Late Cretaceous Agoult Locality In Southeastern Morocco, Mark V. H. Wilson, Alison M. Murray, Terry C. Grande

Terry Grande

No abstract provided.


The Soil Moisture Velocity Equation, Fred L. Ogden, Craig C. Douglas Jun 2017

The Soil Moisture Velocity Equation, Fred L. Ogden, Craig C. Douglas

Fred L. Ogden

Numerical solution of the one-dimensional Richards’ equation is the recommended method for coupling groundwater to the atmosphere through the vadose zone in hyper-resolution Earth system models, but requires fine spatial discretization, is computationally expensive, and may not converge due to mathematical degeneracy or when sharp wetting fronts occur. We transformed the one-dimensional Richards’ equation into a new equation that describes the velocity of moisture content values in an unsaturated soil under the actions of capillarity and gravity. We call this new equation the Soil Moisture Velocity Equation (SMVE). The SMVE consists of two terms: an advection-like term that accounts for …